1523 files changed, 43418 insertions, 21688 deletions

diff --git a/.gitignore b/.gitignore
index bc96284375..9268977c2f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,12 +1,11 @@
 # Don't put *.swp, *.bak, etc here; those belong in a global ~/.gitignore.
 # Check out https://help.github.com/articles/ignoring-files for how to set that up.
 
-debug.log
 .Gemfile
-/.bundle
-/.ruby-version
-/Gemfile.lock
+.ruby-version
+debug.log
 pkg
+/.bundle
 /dist
 /doc/rdoc
 /*/doc
diff --git a/.travis.yml b/.travis.yml
index e4ed59d4a6..46be91d18e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,35 +2,34 @@ language: ruby
 sudo: false
 script: 'ci/travis.rb'
 before_install:
-  - "rvm current | grep 'jruby' && export AR_JDBC=true || echo"
+  - gem install bundler
+  - "rm ${BUNDLE_GEMFILE}.lock"
+  - curl -L https://github.com/kr/beanstalkd/archive/v1.10.tar.gz | tar xz -C /tmp
+  - cd /tmp/beanstalkd-1.10/
+  - make
+  - ./beanstalkd &
+  - cd $TRAVIS_BUILD_DIR
 before_script:
   - bundle update
 cache: bundler
 env:
-  global:
-    - JRUBY_OPTS='-J-Xmx1024M'
   matrix:
     - "GEM=railties"
     - "GEM=ap"
-    - "GEM=aj"
-    - "GEM=am,amo,as,av"
+    - "GEM=am,amo,as,av,aj"
     - "GEM=ar:mysql"
     - "GEM=ar:mysql2"
     - "GEM=ar:sqlite3"
     - "GEM=ar:postgresql"
     - "GEM=aj:integration"
+    - "GEM=guides"
 rvm:
-  - 2.2
+  - 2.2.3
   - ruby-head
-  - rbx-2
-  - jruby
 matrix:
   allow_failures:
     - env: "GEM=ar:mysql"
-    - rvm: rbx-2
-    - rvm: jruby
-    - env: "GEM=aj"
-    - env: "GEM=aj:integration"
+    - rvm: ruby-head
   fast_finish: true
 notifications:
   email: false
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000000..078d5f1219
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,12 @@
+# Contributor Code of Conduct
+
+The Rails team is committed to fostering a welcoming community.
+
+**Our Code of Conduct can be found here**:
+
+http://rubyonrails.org/conduct/
+
+For a history of updates, see the page history here:
+
+https://github.com/rails/rails.github.com/commits/master/conduct/index.html
+
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 421e7088cb..699b6fd2d1 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -8,7 +8,7 @@ Ruby on Rails is a volunteer effort. We encourage you to pitch in. [Join the tea
 
 *We only accept bug reports and pull requests on GitHub*.
 
-* If you have a question about how to use Ruby on Rails, please [ask the rubyonrails-talk mailing list](https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-talk).
+* If you have a question about how to use Ruby on Rails, please [ask it on the rubyonrails-talk mailing list](https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-talk).
 
 * If you have a change or new feature in mind, please [suggest it on the rubyonrails-core mailing list](https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-core) and start writing code.
 
diff --git a/Gemfile b/Gemfile
index eb0a324ab2..260604f570 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,89 +5,93 @@ gemspec
 # We need a newish Rake since Active Job sets its test tasks' descriptions.
 gem 'rake', '>= 10.3'
 
-# This needs to be with require false as it is
-# loaded after loading the test library to
-# ensure correct loading order
+# Active Job depends on URI::GID::MissingModelIDError, which isn't released yet.
+gem 'globalid', github: 'rails/globalid', branch: 'master'
+gem 'rack', github: 'rack/rack', branch: 'master'
+
+# This needs to be with require false to ensure correct loading order, as has to
+# be loaded after loading the test library.
 gem 'mocha', '~> 0.14', require: false
 
 gem 'rack-cache', '~> 1.2'
 gem 'jquery-rails', github: 'rails/jquery-rails', branch: 'master'
 gem 'coffee-rails', '~> 4.1.0'
-gem 'turbolinks'
+gem 'turbolinks', github: 'rails/turbolinks', branch: 'master'
 gem 'arel', github: 'rails/arel', branch: 'master'
+gem 'mail', github: 'mikel/mail', branch: 'master'
+
+gem 'sprockets', '~> 4.0', github: 'rails/sprockets', branch: 'master'
+gem 'sprockets-rails', '~> 3.0.0.beta3', github: 'rails/sprockets-rails', branch: 'master'
+gem 'sass-rails', github: 'rails/sass-rails', branch: 'master'
 
 # require: false so bcrypt is loaded only when has_secure_password is used.
-# This is to avoid ActiveModel (and by extension the entire framework)
+# This is to avoid Active Model (and by extension the entire framework)
 # being dependent on a binary library.
-gem 'bcrypt', '~> 3.1.7', require: false
+gem 'bcrypt', '~> 3.1.10', require: false
 
-# This needs to be with require false to avoid
-# it being automatically loaded by sprockets
+# This needs to be with require false to avoid it being automatically loaded by
+# sprockets.
 gem 'uglifier', '>= 1.3.0', require: false
 
+# Track stable branch of sass because it doesn't have circular require warnings.
+gem 'sass', github: 'sass/sass', branch: 'stable', require: false
+
 group :doc do
   gem 'sdoc', '~> 0.4.0'
-  gem 'redcarpet', '~> 3.2.2', platforms: :ruby
+  gem 'redcarpet', '~> 3.2.3', platforms: :ruby
   gem 'w3c_validators'
-  gem 'kindlerb'
+  gem 'kindlerb', '0.1.1'
 end
 
-# AS
+# Active Support.
 gem 'dalli', '>= 2.2.1'
 
-# ActiveJob
+# Active Job.
 group :job do
   gem 'resque', require: false
   gem 'resque-scheduler', require: false
   gem 'sidekiq', require: false
   gem 'sucker_punch', require: false
   gem 'delayed_job', require: false
-  gem 'queue_classic', "< 3.0.0", require: false, platforms: :ruby
-  gem 'sneakers', '0.1.1.pre', require: false
+  gem 'queue_classic', github: "QueueClassic/queue_classic", branch: 'master', require: false, platforms: :ruby
+  gem 'sneakers', require: false
   gem 'que', require: false
   gem 'backburner', require: false
   gem 'qu-rails', github: "bkeepers/qu", branch: "master", require: false
   gem 'qu-redis', require: false
-  # gem 'delayed_job_active_record', require: false
+  gem 'delayed_job_active_record', require: false
   gem 'sequel', require: false
 end
 
-# Add your own local bundler stuff
+# Add your own local bundler stuff.
 local_gemfile = File.dirname(__FILE__) + "/.Gemfile"
 instance_eval File.read local_gemfile if File.exist? local_gemfile
 
 group :test do
-  # FIX: Our test suite isn't ready to run in random order yet
+  # FIX: Our test suite isn't ready to run in random order yet.
   gem 'minitest', '< 5.3.4'
 
-  platforms :mri_19 do
-    gem 'ruby-prof', '~> 0.11.2'
-  end
-
-  platforms :mri_21 do
+  platforms :mri do
     gem 'stackprof'
+    gem 'byebug'
   end
 
-  # platforms :mri do
-  #   gem 'byebug'
-  # end
-
   gem 'benchmark-ips'
 end
 
 platforms :ruby do
-  gem 'nokogiri', '>= 1.4.5'
+  gem 'nokogiri', '>= 1.6.7.rc3'
 
-  # Needed for compiling the ActionDispatch::Journey parser
+  # Needed for compiling the ActionDispatch::Journey parser.
   gem 'racc', '>=1.4.6', require: false
 
-  # AR
+  # Active Record.
   gem 'sqlite3', '~> 1.3.6'
 
   group :db do
-    gem 'pg', '>= 0.15.0'
+    gem 'pg', '>= 0.18.0'
     gem 'mysql', '>= 2.9.0'
-    gem 'mysql2', '>= 0.3.13'
+    gem 'mysql2', '>= 0.4.0'
   end
 end
 
@@ -109,18 +113,19 @@ platforms :jruby do
 end
 
 platforms :rbx do
-  # The rubysl-yaml gem doesn't ship with Psych by default
-  # as it needs libyaml that isn't always available.
+  # The rubysl-yaml gem doesn't ship with Psych by default as it needs
+  # libyaml that isn't always available.
   gem 'psych', '~> 2.0'
 end
 
-# gems that are necessary for ActiveRecord tests with Oracle database
+# Gems that are necessary for Active Record tests with Oracle.
 if ENV['ORACLE_ENHANCED']
   platforms :ruby do
-    gem 'ruby-oci8', '~> 2.1'
+    gem 'ruby-oci8', '~> 2.2'
   end
   gem 'activerecord-oracle_enhanced-adapter', github: 'rsim/oracle-enhanced', branch: 'master'
 end
 
-# A gem necessary for ActiveRecord tests with IBM DB
+# A gem necessary for Active Record tests with IBM DB.
 gem 'ibm_db' if ENV['IBM_DB']
+gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
diff --git a/Gemfile.lock b/Gemfile.lock
new file mode 100644
index 0000000000..58d2941170
--- /dev/null
+++ b/Gemfile.lock
@@ -0,0 +1,373 @@
+GIT
+  remote: git://github.com/QueueClassic/queue_classic.git
+  revision: d144db29f1436e9e8b3c7a1a1ecd4442316a9ecd
+  branch: master
+  specs:
+    queue_classic (3.2.0.alpha)
+      pg (>= 0.17, < 0.19)
+
+GIT
+  remote: git://github.com/bkeepers/qu.git
+  revision: d098e2657c92e89a6413bebd9c033930759c061f
+  branch: master
+  specs:
+    qu (0.2.0)
+    qu-rails (0.2.0)
+      qu (= 0.2.0)
+      railties (>= 3.2, < 5)
+    qu-redis (0.2.0)
+      qu (= 0.2.0)
+      redis-namespace
+
+GIT
+  remote: git://github.com/mikel/mail.git
+  revision: 9c313a401729b9aa9177878836829a61adf67b54
+  branch: master
+  specs:
+    mail (2.6.3.edge)
+      mime-types (>= 1.16, < 3)
+
+GIT
+  remote: git://github.com/rack/rack.git
+  revision: 35599cfc2751e0ee611c0ff799924b8e7fe0c0b4
+  branch: master
+  specs:
+    rack (2.0.0.alpha)
+      json
+
+GIT
+  remote: git://github.com/rails/arel.git
+  revision: 3c429c5d86e9e2201c2a35d934ca6a8911c18e69
+  branch: master
+  specs:
+    arel (7.0.0.alpha)
+
+GIT
+  remote: git://github.com/rails/globalid.git
+  revision: 1d8fca667740570d204fd955a0bd39ac539bac7f
+  branch: master
+  specs:
+    globalid (0.3.6)
+      activesupport (>= 4.1.0)
+
+GIT
+  remote: git://github.com/rails/jquery-rails.git
+  revision: 04fcfa29b859eef9479f89b6a799d00212902385
+  branch: master
+  specs:
+    jquery-rails (4.0.5)
+      rails-dom-testing (~> 1.0)
+      railties (>= 4.2.0)
+      thor (>= 0.14, < 2.0)
+
+GIT
+  remote: git://github.com/rails/sass-rails.git
+  revision: 6e4eee736bcbfa5b2962467673c7a51abf434c67
+  branch: master
+  specs:
+    sass-rails (6.0.0)
+      railties (>= 4.0.0, < 5.0)
+      sass (~> 3.4)
+      sprockets (>= 4.0)
+      sprockets-rails (< 4.0)
+
+GIT
+  remote: git://github.com/rails/sprockets-rails.git
+  revision: 93a45b1c463a063ec7cf4d160107b67aa3db7a1a
+  branch: master
+  specs:
+    sprockets-rails (3.0.0.beta3)
+      actionpack (>= 4.0)
+      activesupport (>= 4.0)
+      sprockets (>= 3.0.0)
+
+GIT
+  remote: git://github.com/rails/sprockets.git
+  revision: 5a77f8b007b8ec61edd783c48baf9d971f1c684d
+  branch: master
+  specs:
+    sprockets (4.0.0)
+      rack (>= 1, < 3)
+
+GIT
+  remote: git://github.com/rails/turbolinks.git
+  revision: 83d4b3d2c52a681f07900c28adb28bc8da604733
+  branch: master
+  specs:
+    turbolinks (3.0.0)
+      coffee-rails
+
+GIT
+  remote: git://github.com/sass/sass.git
+  revision: 4e3e1d5684cc29073a507578fc977434ff488c93
+  branch: stable
+  specs:
+    sass (3.4.19)
+
+PATH
+  remote: .
+  specs:
+    actionmailer (5.0.0.alpha)
+      actionpack (= 5.0.0.alpha)
+      actionview (= 5.0.0.alpha)
+      activejob (= 5.0.0.alpha)
+      mail (~> 2.5, >= 2.5.4)
+      rails-dom-testing (~> 1.0, >= 1.0.5)
+    actionpack (5.0.0.alpha)
+      actionview (= 5.0.0.alpha)
+      activesupport (= 5.0.0.alpha)
+      rack (~> 2.x)
+      rack-test (~> 0.6.3)
+      rails-dom-testing (~> 1.0, >= 1.0.5)
+      rails-html-sanitizer (~> 1.0, >= 1.0.2)
+    actionview (5.0.0.alpha)
+      activesupport (= 5.0.0.alpha)
+      builder (~> 3.1)
+      erubis (~> 2.7.0)
+      rails-dom-testing (~> 1.0, >= 1.0.5)
+      rails-html-sanitizer (~> 1.0, >= 1.0.2)
+    activejob (5.0.0.alpha)
+      activesupport (= 5.0.0.alpha)
+      globalid (>= 0.3.0)
+    activemodel (5.0.0.alpha)
+      activesupport (= 5.0.0.alpha)
+      builder (~> 3.1)
+    activerecord (5.0.0.alpha)
+      activemodel (= 5.0.0.alpha)
+      activesupport (= 5.0.0.alpha)
+      arel (= 7.0.0.alpha)
+    activesupport (5.0.0.alpha)
+      concurrent-ruby (~> 1.0.0.pre3, < 2.0.0)
+      i18n (~> 0.7)
+      json (~> 1.7, >= 1.7.7)
+      method_source
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
+    rails (5.0.0.alpha)
+      actionmailer (= 5.0.0.alpha)
+      actionpack (= 5.0.0.alpha)
+      actionview (= 5.0.0.alpha)
+      activejob (= 5.0.0.alpha)
+      activemodel (= 5.0.0.alpha)
+      activerecord (= 5.0.0.alpha)
+      activesupport (= 5.0.0.alpha)
+      bundler (>= 1.3.0, < 2.0)
+      railties (= 5.0.0.alpha)
+      sprockets-rails (>= 2.0.0)
+    railties (5.0.0.alpha)
+      actionpack (= 5.0.0.alpha)
+      activesupport (= 5.0.0.alpha)
+      method_source
+      rake (>= 0.8.7)
+      thor (>= 0.18.1, < 2.0)
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    amq-protocol (2.0.0)
+    backburner (1.1.0)
+      beaneater (~> 1.0)
+      dante (> 0.1.5)
+    bcrypt (3.1.10)
+    bcrypt (3.1.10-x64-mingw32)
+    bcrypt (3.1.10-x86-mingw32)
+    beaneater (1.0.0)
+    benchmark-ips (2.3.0)
+    builder (3.2.2)
+    bunny (2.2.0)
+      amq-protocol (>= 2.0.0)
+    byebug (6.0.2)
+    celluloid (0.17.2)
+      celluloid-essentials
+      celluloid-extras
+      celluloid-fsm
+      celluloid-pool
+      celluloid-supervision
+      timers (>= 4.1.1)
+    celluloid-essentials (0.20.5)
+      timers (>= 4.1.1)
+    celluloid-extras (0.20.5)
+      timers (>= 4.1.1)
+    celluloid-fsm (0.20.5)
+      timers (>= 4.1.1)
+    celluloid-pool (0.20.5)
+      timers (>= 4.1.1)
+    celluloid-supervision (0.20.5)
+      timers (>= 4.1.1)
+    coffee-rails (4.1.0)
+      coffee-script (>= 2.2.0)
+      railties (>= 4.0.0, < 5.0)
+    coffee-script (2.4.1)
+      coffee-script-source
+      execjs
+    coffee-script-source (1.9.1.1)
+    concurrent-ruby (1.0.0.pre4)
+    connection_pool (2.2.0)
+    dalli (2.7.4)
+    dante (0.2.0)
+    delayed_job (4.1.1)
+      activesupport (>= 3.0, < 5.0)
+    delayed_job_active_record (4.1.0)
+      activerecord (>= 3.0, < 5)
+      delayed_job (>= 3.0, < 5)
+    erubis (2.7.0)
+    execjs (2.6.0)
+    hitimes (1.2.3)
+    hitimes (1.2.3-x86-mingw32)
+    i18n (0.7.0)
+    json (1.8.3)
+    kindlerb (0.1.1)
+      mustache
+      nokogiri
+    loofah (2.0.3)
+      nokogiri (>= 1.5.9)
+    metaclass (0.0.4)
+    method_source (0.8.2)
+    mime-types (2.6.2)
+    mini_portile (0.7.0.rc4)
+    minitest (5.3.3)
+    mocha (0.14.0)
+      metaclass (~> 0.0.1)
+    mono_logger (1.1.0)
+    multi_json (1.11.2)
+    mustache (1.0.2)
+    mysql (2.9.1)
+    mysql2 (0.4.1)
+    nokogiri (1.6.7.rc3)
+      mini_portile (~> 0.7.0.rc4)
+    pg (0.18.3)
+    psych (2.0.15)
+    que (0.11.2)
+    racc (1.4.13)
+    rack-cache (1.5.0)
+      rack (>= 0.4)
+    rack-test (0.6.3)
+      rack (>= 1.0)
+    rails-deprecated_sanitizer (1.0.3)
+      activesupport (>= 4.2.0.alpha)
+    rails-dom-testing (1.0.7)
+      activesupport (>= 4.2.0.beta, < 5.0)
+      nokogiri (~> 1.6.0)
+      rails-deprecated_sanitizer (>= 1.0.1)
+    rails-html-sanitizer (1.0.2)
+      loofah (~> 2.0)
+    rake (10.4.2)
+    rdoc (4.2.0)
+    redcarpet (3.2.3)
+    redis (3.2.1)
+    redis-namespace (1.5.2)
+      redis (~> 3.0, >= 3.0.4)
+    resque (1.25.2)
+      mono_logger (~> 1.0)
+      multi_json (~> 1.0)
+      redis-namespace (~> 1.3)
+      sinatra (>= 0.9.2)
+      vegas (~> 0.1.2)
+    resque-scheduler (4.0.0)
+      mono_logger (~> 1.0)
+      redis (~> 3.0)
+      resque (~> 1.25)
+      rufus-scheduler (~> 3.0)
+    rufus-scheduler (3.1.7)
+    sdoc (0.4.1)
+      json (~> 1.7, >= 1.7.7)
+      rdoc (~> 4.0)
+    sequel (4.27.0)
+    serverengine (1.5.11)
+      sigdump (~> 0.2.2)
+    sidekiq (3.5.1)
+      celluloid (~> 0.17.2)
+      connection_pool (~> 2.2, >= 2.2.0)
+      json (~> 1.0)
+      redis (~> 3.2, >= 3.2.1)
+      redis-namespace (~> 1.5, >= 1.5.2)
+    sigdump (0.2.3)
+    sinatra (1.0)
+      rack (>= 1.0)
+    sneakers (2.3.5)
+      bunny (~> 2.2.0)
+      serverengine (~> 1.5.11)
+      thor
+      thread (~> 0.1.7)
+    sqlite3 (1.3.11)
+    stackprof (0.2.7)
+    sucker_punch (1.6.0)
+      celluloid (~> 0.17.2)
+    thor (0.19.1)
+    thread (0.1.7)
+    thread_safe (0.3.5)
+    timers (4.1.1)
+      hitimes
+    tzinfo (1.2.2)
+      thread_safe (~> 0.1)
+    tzinfo-data (1.2015.7)
+      tzinfo (>= 1.0.0)
+    uglifier (2.7.2)
+      execjs (>= 0.3.0)
+      json (>= 1.8.0)
+    vegas (0.1.11)
+      rack (>= 1.0.0)
+    w3c_validators (1.2)
+      json
+      nokogiri
+
+PLATFORMS
+  ruby
+  x64-mingw32
+  x86-mingw32
+
+DEPENDENCIES
+  activerecord-jdbcmysql-adapter (>= 1.3.0)
+  activerecord-jdbcpostgresql-adapter (>= 1.3.0)
+  activerecord-jdbcsqlite3-adapter (>= 1.3.0)
+  arel!
+  backburner
+  bcrypt (~> 3.1.10)
+  benchmark-ips
+  byebug
+  coffee-rails (~> 4.1.0)
+  dalli (>= 2.2.1)
+  delayed_job
+  delayed_job_active_record
+  globalid!
+  jquery-rails!
+  json
+  kindlerb (= 0.1.1)
+  mail!
+  minitest (< 5.3.4)
+  mocha (~> 0.14)
+  mysql (>= 2.9.0)
+  mysql2 (>= 0.4.0)
+  nokogiri (>= 1.6.7.rc3)
+  pg (>= 0.18.0)
+  psych (~> 2.0)
+  qu-rails!
+  qu-redis
+  que
+  queue_classic!
+  racc (>= 1.4.6)
+  rack!
+  rack-cache (~> 1.2)
+  rails!
+  rake (>= 10.3)
+  redcarpet (~> 3.2.3)
+  resque
+  resque-scheduler
+  sass!
+  sass-rails!
+  sdoc (~> 0.4.0)
+  sequel
+  sidekiq
+  sneakers
+  sprockets (~> 4.0)!
+  sprockets-rails (~> 3.0.0.beta3)!
+  sqlite3 (~> 1.3.6)
+  stackprof
+  sucker_punch
+  turbolinks!
+  tzinfo-data
+  uglifier (>= 1.3.0)
+  w3c_validators
+
+BUNDLED WITH
+   1.10.6
diff --git a/README.md b/README.md
index bbe3a6731d..f823a49f7d 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@ Ruby code (ERB files). Views are typically rendered to generate a controller res
 or to generate the body of an email. In Rails, View generation is handled by Action View.
 You can read more about Action View in its [README](actionview/README.rdoc).
 
-Active Record, Action Pack, and Action View can each be used independently outside Rails.
+Active Record, Active Model, Action Pack, and Action View can each be used independently outside Rails.
 In addition to them, Rails also comes with Action Mailer ([README](actionmailer/README.rdoc)), a library
 to generate and send emails; Active Job ([README](activejob/README.md)), a
 framework for declaring jobs and making them run on a variety of queueing
@@ -76,6 +76,8 @@ and may also be used independently outside Rails.
 We encourage you to contribute to Ruby on Rails! Please check out the
 [Contributing to Ruby on Rails guide](http://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html) for guidelines about how to proceed. [Join us!](http://contributors.rubyonrails.org)
 
+Everyone interacting in Rails and its sub-projects' codebases, issue trackers, chat rooms, and mailing lists is expected to follow the Rails [code of conduct](http://rubyonrails.org/conduct/).
+
 ## Code Status
 
 [![Build Status](https://travis-ci.org/rails/rails.svg?branch=master)](https://travis-ci.org/rails/rails)
diff --git a/RELEASING_RAILS.rdoc b/RELEASING_RAILS.md
index 0e09234b82..faf8fa7f0d 100644
--- a/RELEASING_RAILS.rdoc
+++ b/RELEASING_RAILS.md
@@ -1,43 +1,47 @@
-= Releasing Rails
+# Releasing Rails
 
 In this document, we'll cover the steps necessary to release Rails.  Each
 section contains steps to take during that time before the release.  The times
 suggested in each header are just that: suggestions.  However, they should
 really be considered as minimums.
 
-== 10 Days before release
+## 10 Days before release
 
 Today is mostly coordination tasks.  Here are the things you must do today:
 
-=== Is the CI green?  If not, make it green. (See "Fixing the CI")
+### Is the CI green?  If not, make it green. (See "Fixing the CI")
 
 Do not release with a Red CI.  You can find the CI status here:
 
-  http://travis-ci.org/rails/rails
+```
+http://travis-ci.org/rails/rails
+```
 
-=== Is Sam Ruby happy?  If not, make him happy.
+### Is Sam Ruby happy?  If not, make him happy.
 
 Sam Ruby keeps a test suite that makes sure the code samples in his book (Agile
 Web Development with Rails) all work.  These are valuable integration tests
 for Rails.  You can check the status of his tests here:
 
-  http://intertwingly.net/projects/dashboard.html
+```
+http://intertwingly.net/projects/dashboard.html
+```
 
 Do not release with Red AWDwR tests.
 
-=== Do we have any Git dependencies?  If so, contact those authors.
+### Do we have any Git dependencies?  If so, contact those authors.
 
 Having Git dependencies indicates that we depend on unreleased code.
 Obviously Rails cannot be released when it depends on unreleased code.
 Contact the authors of those particular gems and work out a release date that
 suits them.
 
-=== Contact the security team (either Koz or tenderlove)
+### Contact the security team (either Koz or tenderlove)
 
 Let them know of your plans to release.  There may be security issues to be
 addressed, and that can impact your release date.
 
-=== Notify implementors.
+### Notify implementors.
 
 Ruby implementors have high stakes in making sure Rails works.  Be kind and
 give them a heads up that Rails will be released soonish.
@@ -54,27 +58,29 @@ lists:
 
 Implementors will love you and help you.
 
-== 3 Days before release
+### 3 Days before release
 
 This is when you should release the release candidate.  Here are your tasks
 for today:
 
-=== Is the CI green?  If not, make it green.
+### Is the CI green?  If not, make it green.
 
-=== Is Sam Ruby happy?  If not, make him happy.
+### Is Sam Ruby happy?  If not, make him happy.
 
-=== Contact the security team.  CVE emails must be sent on this day.
+### Contact the security team.  CVE emails must be sent on this day.
 
-=== Create a release branch.
+### Create a release branch.
 
 From the stable branch, create a release branch.  For example, if you're
 releasing Rails 3.0.10, do this:
 
-    [aaron@higgins rails (3-0-stable)]$ git checkout -b 3-0-10
-    Switched to a new branch '3-0-10'
-    [aaron@higgins rails (3-0-10)]$
+```
+[aaron@higgins rails (3-0-stable)]$ git checkout -b 3-0-10
+Switched to a new branch '3-0-10'
+[aaron@higgins rails (3-0-10)]$
+```
 
-=== Update each CHANGELOG.
+### Update each CHANGELOG.
 
 Many times commits are made without the CHANGELOG being updated.  You should
 review the commits since the last release, and fill in any missing information
@@ -82,23 +88,25 @@ for each CHANGELOG.
 
 You can review the commits for the 3.0.10 release like this:
 
-    [aaron@higgins rails (3-0-10)]$ git log v3.0.9..
+```
+[aaron@higgins rails (3-0-10)]$ git log v3.0.9..
+```
 
 If you're doing a stable branch release, you should also ensure that all of
 the CHANGELOG entries in the stable branch are also synced to the master
 branch.
 
-=== Update the RAILS_VERSION file to include the RC.
+### Update the RAILS_VERSION file to include the RC.
 
-=== Build and test the gem.
+### Build and test the gem.
 
 Run `rake install` to generate the gems and install them locally. Then try
 generating a new app and ensure that nothing explodes.
 
 This will stop you from looking silly when you push an RC to rubygems.org and
-then realise it is broken.
+then realize it is broken.
 
-=== Release the gem.
+### Release the gem.
 
 IMPORTANT: Due to YAML parse problems on the rubygems.org server, it is safest
 to use Ruby 1.8 when releasing.
@@ -108,14 +116,16 @@ RAILS_VERSION, commit the changes, tag it, and push the gems to rubygems.org.
 Here are the commands that `rake release` should use, so you can understand
 what to do in case anything goes wrong:
 
-    $ rake all:build
-    $ git commit -am'updating RAILS_VERSION'
-    $ git tag -m 'v3.0.10.rc1 release' v3.0.10.rc1
-    $ git push
-    $ git push --tags
-    $ for i in $(ls pkg); do gem push $i; done
+```
+$ rake all:build
+$ git commit -am'updating RAILS_VERSION'
+$ git tag -m 'v3.0.10.rc1 release' v3.0.10.rc1
+$ git push
+$ git push --tags
+$ for i in $(ls pkg); do gem push $i; done
+```
 
-=== Send Rails release announcements
+### Send Rails release announcements
 
 Write a release announcement that includes the version, changes, and links to
 GitHub where people can find the specific commit list.  Here are the mailing
@@ -132,16 +142,16 @@ IMPORTANT: If any users experience regressions when using the release
 candidate, you *must* postpone the release.  Bugfix releases *should not*
 break existing applications.
 
-=== Post the announcement to the Rails blog.
+### Post the announcement to the Rails blog.
 
 If you used Markdown format for your email, you can just paste it in to the
 blog.
 
 * http://weblog.rubyonrails.org
 
-=== Post the announcement to the Rails Twitter account.
+### Post the announcement to the Rails Twitter account.
 
-== Time between release candidate and actual release
+## Time between release candidate and actual release
 
 Check the rails-core mailing list and the GitHub issue list for regressions in
 the RC.
@@ -155,7 +165,7 @@ When you fix the regressions, do not create a new branch.  Fix them on the
 stable branch, then cherry pick the commit to your release branch.  No other
 commits should be added to the release branch besides regression fixing commits.
 
-== Day of release
+## Day of release
 
 Many of these steps are the same as for the release candidate, so if you need
 more explanation on a particular step, see the RC steps.
@@ -173,7 +183,7 @@ Today, do this stuff in this order:
 * Email security lists
 * Email general announcement lists
 
-=== Emailing the Rails security announce list
+### Emailing the Rails security announce list
 
 Email the security announce list once for each vulnerability fixed.
 
@@ -193,13 +203,13 @@ so we need to give them the security fixes in patch form.
 * Merge the release branch to the stable branch.
 * Drink beer (or other cocktail)
 
-== Misc
+## Misc
 
-=== Fixing the CI
+### Fixing the CI
 
 There are two simple steps for fixing the CI:
 
 1. Identify the problem
 2. Fix it
 
-Repeat these steps until the CI is green.
+Repeat these steps until the CI is green.
\ No newline at end of file
diff --git a/Rakefile b/Rakefile
index db27105cc3..2ec39a1c85 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,4 +1,3 @@
-require 'sdoc'
 require 'net/http'
 
 $:.unshift File.expand_path('..', __FILE__)
diff --git a/actionmailer/CHANGELOG.md b/actionmailer/CHANGELOG.md
index 008760f2fc..0ecb0235bc 100644
--- a/actionmailer/CHANGELOG.md
+++ b/actionmailer/CHANGELOG.md
@@ -1,5 +1,43 @@
+*   `config.force_ssl = true` will set
+    `config.action_mailer.default_url_options = { protocol: 'https' }`
+
+    *Andrew Kampjes*
+
+*   Add `config.action_mailer.deliver_later_queue_name` configuration to set the
+    mailer queue name.
+
+    *Chris McGrath*
+
+*   `assert_emails` in block form use the given number as expected value.
+    This makes the error message much easier to understand.
+
+    *Yuji Yaginuma*
+
+*   Add support for inline images in mailer previews by using an interceptor
+    class to convert cid: urls in image src attributes to data urls.
+
+    *Andrew White*
+
+*   Mailer preview now uses `url_for` to fix links to emails for apps running on
+    a subdirectory.
+
+    *Remo Mueller*
+
+*   Mailer previews no longer crash when the `mail` method wasn't called
+    (`NullMail`).
+
+    Fixes #19849.
+
+    *Yves Senn*
+
+*   Make sure labels and values line up in mailer previews.
+
+    *Yves Senn*
+
 *   Add `assert_enqueued_emails` and `assert_no_enqueued_emails`.
 
+    Example:
+
         def test_emails
           assert_enqueued_emails 2 do
             ContactMailer.welcome.deliver_later
diff --git a/actionmailer/README.rdoc b/actionmailer/README.rdoc
index a4e660d621..e5c2ed8c77 100644
--- a/actionmailer/README.rdoc
+++ b/actionmailer/README.rdoc
@@ -146,7 +146,7 @@ The Base class has the full list of configuration options. Here's an example:
 
 The latest version of Action Mailer can be installed with RubyGems:
 
-  % [sudo] gem install actionmailer
+  % gem install actionmailer
 
 Source code can be downloaded as part of the Rails project on GitHub
 
diff --git a/actionmailer/Rakefile b/actionmailer/Rakefile
index 8f4de8fafa..7197ea5e27 100644
--- a/actionmailer/Rakefile
+++ b/actionmailer/Rakefile
@@ -1,5 +1,4 @@
 require 'rake/testtask'
-require 'rubygems/package_task'
 
 desc "Default Task"
 task default: [ :test ]
@@ -20,16 +19,3 @@ namespace :test do
     end or raise "Failures"
   end
 end
-
-spec = eval(File.read('actionmailer.gemspec'))
-
-Gem::PackageTask.new(spec) do |p|
-  p.gem_spec = spec
-end
-
-desc "Release to rubygems"
-task release: :package do
-  require 'rake/gemcutter'
-  Rake::Gemcutter::Tasks.new(spec).define
-  Rake::Task['gem:push'].invoke
-end
diff --git a/actionmailer/actionmailer.gemspec b/actionmailer/actionmailer.gemspec
index 513c217733..782b208ef4 100644
--- a/actionmailer/actionmailer.gemspec
+++ b/actionmailer/actionmailer.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'Email composition, delivery, and receiving framework (part of Rails).'
   s.description = 'Email on Rails. Compose, deliver, receive, and test emails using the familiar controller/view pattern. First-class support for multipart email and attachments.'
 
-  s.required_ruby_version = '>= 2.2.0'
+  s.required_ruby_version = '>= 2.2.2'
 
   s.license = 'MIT'
 
diff --git a/actionmailer/bin/test b/actionmailer/bin/test
new file mode 100755
index 0000000000..404cabba51
--- /dev/null
+++ b/actionmailer/bin/test
@@ -0,0 +1,4 @@
+#!/usr/bin/env ruby
+COMPONENT_ROOT = File.expand_path("../../", __FILE__)
+require File.expand_path("../tools/test", COMPONENT_ROOT)
+exit Minitest.run(ARGV)
diff --git a/actionmailer/lib/action_mailer.rb b/actionmailer/lib/action_mailer.rb
index 17d8dcc208..312dd1997c 100644
--- a/actionmailer/lib/action_mailer.rb
+++ b/actionmailer/lib/action_mailer.rb
@@ -40,6 +40,7 @@ module ActionMailer
 
   autoload :Base
   autoload :DeliveryMethods
+  autoload :InlinePreviewInterceptor
   autoload :MailHelper
   autoload :Preview
   autoload :Previews, 'action_mailer/preview'
@@ -48,3 +49,10 @@ module ActionMailer
   autoload :MessageDelivery
   autoload :DeliveryJob
 end
+
+autoload :Mime, 'action_dispatch/http/mime_type'
+
+ActiveSupport.on_load(:action_view) do
+  ActionView::Base.default_formats ||= Mime::SET.symbols
+  ActionView::Template::Types.delegate_to Mime
+end
diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 7eae76f93b..c9e7f7d0d3 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -21,11 +21,11 @@ module ActionMailer
   # the mailer views, options on the mail itself such as the <tt>:from</tt> address, and attachments.
   #
   #   class ApplicationMailer < ActionMailer::Base
-  #     default from: 'from@exmaple.com'
+  #     default from: 'from@example.com'
   #     layout 'mailer'
   #   end
   #
-  #   class Notifier < ApplicationMailer
+  #   class NotifierMailer < ApplicationMailer
   #     default from: 'no-reply@example.com',
   #             return_path: 'system@example.com'
   #
@@ -88,7 +88,7 @@ module ActionMailer
   #
   # To define a template to be used with a mailing, create an <tt>.erb</tt> file with the same
   # name as the method in your mailer model. For example, in the mailer defined above, the template at
-  # <tt>app/views/notifier/welcome.text.erb</tt> would be used to generate the email.
+  # <tt>app/views/notifier_mailer/welcome.text.erb</tt> would be used to generate the email.
   #
   # Variables defined in the methods of your mailer model are accessible as instance variables in their
   # corresponding view.
@@ -132,27 +132,32 @@ module ActionMailer
   #
   #   config.action_mailer.default_url_options = { host: "example.com" }
   #
+  # By default when <tt>config.force_ssl</tt> is true, URLs generated for hosts will use the HTTPS protocol.
+  #
   # = Sending mail
   #
-  # Once a mailer action and template are defined, you can deliver your message or create it and save it
-  # for delivery later:
+  # Once a mailer action and template are defined, you can deliver your message or defer its creation and
+  # delivery for later:
+  #
+  #   NotifierMailer.welcome(User.first).deliver_now # sends the email
+  #   mail = NotifierMailer.welcome(User.first)      # => an ActionMailer::MessageDelivery object
+  #   mail.deliver_now                               # generates and sends the email now
   #
-  #   Notifier.welcome(User.first).deliver_now # sends the email
-  #   mail = Notifier.welcome(User.first)      # => an ActionMailer::MessageDelivery object
-  #   mail.deliver_now                    # sends the email
+  # The <tt>ActionMailer::MessageDelivery</tt> class is a wrapper around a delegate that will call
+  # your method to generate the mail. If you want direct access to delegator, or <tt>Mail::Message</tt>,
+  # you can call the <tt>message</tt> method on the <tt>ActionMailer::MessageDelivery</tt> object.
   #
-  # The <tt>ActionMailer::MessageDelivery</tt> class is a wrapper around a <tt>Mail::Message</tt> object. If
-  # you want direct access to the <tt>Mail::Message</tt> object you can call the <tt>message</tt> method on
-  # the <tt>ActionMailer::MessageDelivery</tt> object.
+  #   NotifierMailer.welcome(User.first).message     # => a Mail::Message object
   #
-  #   Notifier.welcome(User.first).message     # => a Mail::Message object
+  # Action Mailer is nicely integrated with Active Job so you can generate and send emails in the background
+  # (example: outside of the request-response cycle, so the user doesn't have to wait on it):
   #
-  # Action Mailer is nicely integrated with Active Job so you can send emails in the background (example: outside
-  # of the request-response cycle, so the user doesn't have to wait on it):
+  #   NotifierMailer.welcome(User.first).deliver_later # enqueue the email sending to Active Job
   #
-  #   Notifier.welcome(User.first).deliver_later # enqueue the email sending to Active Job
+  # Note that <tt>deliver_later</tt> will execute your method from the background job.
   #
   # You never instantiate your mailer class. Rather, you just call the method you defined on the class itself.
+  # All instance methods are expected to return a message object to be sent.
   #
   # = Multipart Emails
   #
@@ -179,7 +184,7 @@ module ActionMailer
   #
   # Sending attachment in emails is easy:
   #
-  #   class Notifier < ApplicationMailer
+  #   class NotifierMailer < ApplicationMailer
   #     def welcome(recipient)
   #       attachments['free_book.pdf'] = File.read('path/to/file.pdf')
   #       mail(to: recipient, subject: "New account information")
@@ -195,7 +200,7 @@ module ActionMailer
   # If you need to send attachments with no content, you need to create an empty view for it,
   # or add an empty body parameter like this:
   #
-  #     class Notifier < ApplicationMailer
+  #     class NotifierMailer < ApplicationMailer
   #       def welcome(recipient)
   #         attachments['free_book.pdf'] = File.read('path/to/file.pdf')
   #         mail(to: recipient, subject: "New account information", body: "")
@@ -207,7 +212,7 @@ module ActionMailer
   # You can also specify that a file should be displayed inline with other HTML. This is useful
   # if you want to display a corporate logo or a photo.
   #
-  #   class Notifier < ApplicationMailer
+  #   class NotifierMailer < ApplicationMailer
   #     def welcome(recipient)
   #       attachments.inline['photo.png'] = File.read('path/to/photo.png')
   #       mail(to: recipient, subject: "Here is what we look like")
@@ -246,7 +251,7 @@ module ActionMailer
   # Action Mailer provides some intelligent defaults for your emails, these are usually specified in a
   # default method inside the class definition:
   #
-  #   class Notifier < ApplicationMailer
+  #   class NotifierMailer < ApplicationMailer
   #     default sender: 'system@example.com'
   #   end
   #
@@ -254,8 +259,8 @@ module ActionMailer
   # <tt>ActionMailer::Base</tt> sets the following:
   #
   # * <tt>mime_version: "1.0"</tt>
-  # * <tt>charset:      "UTF-8",</tt>
-  # * <tt>content_type: "text/plain",</tt>
+  # * <tt>charset:      "UTF-8"</tt>
+  # * <tt>content_type: "text/plain"</tt>
   # * <tt>parts_order:  [ "text/plain", "text/enriched", "text/html" ]</tt>
   #
   # <tt>parts_order</tt> and <tt>charset</tt> are not actually valid <tt>Mail::Message</tt> header fields,
@@ -264,7 +269,7 @@ module ActionMailer
   # As you can pass in any header, you need to either quote the header as a string, or pass it in as
   # an underscored symbol, so the following will work:
   #
-  #   class Notifier < ApplicationMailer
+  #   class NotifierMailer < ApplicationMailer
   #     default 'Content-Transfer-Encoding' => '7bit',
   #             content_description: 'This is a description'
   #   end
@@ -272,7 +277,7 @@ module ActionMailer
   # Finally, Action Mailer also supports passing <tt>Proc</tt> objects into the default hash, so you
   # can define methods that evaluate as the message is being generated:
   #
-  #   class Notifier < ApplicationMailer
+  #   class NotifierMailer < ApplicationMailer
   #     default 'X-Special-Header' => Proc.new { my_method }
   #
   #     private
@@ -283,7 +288,7 @@ module ActionMailer
   #   end
   #
   # Note that the proc is evaluated right at the start of the mail message generation, so if you
-  # set something in the defaults using a proc, and then set the same thing inside of your
+  # set something in the default using a proc, and then set the same thing inside of your
   # mailer method, it will get over written by the mailer method.
   #
   # It is also possible to set these default options that will be used in all mailers through
@@ -297,7 +302,7 @@ module ActionMailer
   # This may be useful, for example, when you want to add default inline attachments for all
   # messages sent out by a certain mailer class:
   #
-  #   class Notifier < ApplicationMailer
+  #   class NotifierMailer < ApplicationMailer
   #     before_action :add_inline_attachment!
   #
   #     def welcome
@@ -316,8 +321,9 @@ module ActionMailer
   # callbacks in the same manner that you would use callbacks in classes that
   # inherit from <tt>ActionController::Base</tt>.
   #
-  # Note that unless you have a specific reason to do so, you should prefer using before_action
-  # rather than after_action in your Action Mailer classes so that headers are parsed properly.
+  # Note that unless you have a specific reason to do so, you should prefer
+  # using <tt>before_action</tt> rather than <tt>after_action</tt> in your
+  # Action Mailer classes so that headers are parsed properly.
   #
   # = Previewing emails
   #
@@ -325,9 +331,9 @@ module ActionMailer
   # <tt>ActionMailer::Base.preview_path</tt>. Since most emails do something interesting
   # with database data, you'll need to write some scenarios to load messages with fake data:
   #
-  #   class NotifierPreview < ActionMailer::Preview
+  #   class NotifierMailerPreview < ActionMailer::Preview
   #     def welcome
-  #       Notifier.welcome(User.first)
+  #       NotifierMailer.welcome(User.first)
   #     end
   #   end
   #
@@ -376,8 +382,8 @@ module ActionMailer
   #   * <tt>:password</tt> - If your mail server requires authentication, set the password in this setting.
   #   * <tt>:authentication</tt> - If your mail server requires authentication, you need to specify the
   #     authentication type here.
-  #     This is a symbol and one of <tt>:plain</tt> (will send the password in the clear), <tt>:login</tt> (will
-  #     send password Base64 encoded) or <tt>:cram_md5</tt> (combines a Challenge/Response mechanism to exchange
+  #     This is a symbol and one of <tt>:plain</tt> (will send the password Base64 encoded), <tt>:login</tt> (will
+  #     send the password Base64 encoded) or <tt>:cram_md5</tt> (combines a Challenge/Response mechanism to exchange
   #     information and a cryptographic Message Digest 5 algorithm to hash important information)
   #   * <tt>:enable_starttls_auto</tt> - Detects if STARTTLS is enabled in your SMTP server and starts
   #     to use it. Defaults to <tt>true</tt>.
@@ -409,6 +415,8 @@ module ActionMailer
   #
   # * <tt>deliveries</tt> - Keeps an array of all the emails sent out through the Action Mailer with
   #   <tt>delivery_method :test</tt>. Most useful for unit and functional testing.
+  #
+  # * <tt>deliver_later_queue_name</tt> - The name of the queue used with <tt>deliver_later</tt>.
   class Base < AbstractController::Base
     include DeliveryMethods
     include Previews
@@ -593,6 +601,7 @@ module ActionMailer
 
     class NullMail #:nodoc:
       def body; '' end
+      def header; {} end
 
       def respond_to?(string, include_all=false)
         true
@@ -813,7 +822,7 @@ module ActionMailer
       # Set configure delivery behavior
       wrap_delivery_behavior!(headers.delete(:delivery_method), headers.delete(:delivery_method_options))
 
-      # Assign all headers except parts_order, content_type and body
+      # Assign all headers except parts_order, content_type, body, template_name, and template_path
       assignable = headers.except(:parts_order, :content_type, :body, :template_name, :template_path)
       assignable.each { |k, v| m[k] = v }
 
diff --git a/actionmailer/lib/action_mailer/delivery_job.rb b/actionmailer/lib/action_mailer/delivery_job.rb
index e864ab7a4d..52772af2d3 100644
--- a/actionmailer/lib/action_mailer/delivery_job.rb
+++ b/actionmailer/lib/action_mailer/delivery_job.rb
@@ -4,7 +4,7 @@ module ActionMailer
   # The <tt>ActionMailer::DeliveryJob</tt> class is used when you
   # want to send emails outside of the request-response cycle.
   class DeliveryJob < ActiveJob::Base # :nodoc:
-    queue_as :mailers
+    queue_as { ActionMailer::Base.deliver_later_queue_name }
 
     def perform(mailer, mail_method, delivery_method, *args) #:nodoc:
       mailer.constantize.public_send(mail_method, *args).send(delivery_method)
diff --git a/actionmailer/lib/action_mailer/delivery_methods.rb b/actionmailer/lib/action_mailer/delivery_methods.rb
index aedcd81e52..4758b55a2a 100644
--- a/actionmailer/lib/action_mailer/delivery_methods.rb
+++ b/actionmailer/lib/action_mailer/delivery_methods.rb
@@ -16,6 +16,9 @@ module ActionMailer
       cattr_accessor :perform_deliveries
       self.perform_deliveries = true
 
+      cattr_accessor :deliver_later_queue_name
+      self.deliver_later_queue_name = :mailers
+
       self.delivery_methods = {}.freeze
       self.delivery_method  = :smtp
 
diff --git a/actionmailer/lib/action_mailer/gem_version.rb b/actionmailer/lib/action_mailer/gem_version.rb
index ac79788cf0..b35d2ed965 100644
--- a/actionmailer/lib/action_mailer/gem_version.rb
+++ b/actionmailer/lib/action_mailer/gem_version.rb
@@ -1,5 +1,5 @@
 module ActionMailer
-  # Returns the version of the currently loaded Action Mailer as a <tt>Gem::Version</tt>
+  # Returns the version of the currently loaded Action Mailer as a <tt>Gem::Version</tt>.
   def self.gem_version
     Gem::Version.new VERSION::STRING
   end
diff --git a/actionmailer/lib/action_mailer/inline_preview_interceptor.rb b/actionmailer/lib/action_mailer/inline_preview_interceptor.rb
new file mode 100644
index 0000000000..6d02b39225
--- /dev/null
+++ b/actionmailer/lib/action_mailer/inline_preview_interceptor.rb
@@ -0,0 +1,61 @@
+require 'base64'
+
+module ActionMailer
+  # Implements a mailer preview interceptor that converts image tag src attributes
+  # that use inline cid: style urls to data: style urls so that they are visible
+  # when previewing a HTML email in a web browser.
+  #
+  # This interceptor is enabled by default. To disable it, delete it from the
+  # <tt>ActionMailer::Base.preview_interceptors</tt> array:
+  #
+  #   ActionMailer::Base.preview_interceptors.delete(ActionMailer::InlinePreviewInterceptor)
+  #
+  class InlinePreviewInterceptor
+    PATTERN  = /src=(?:"cid:[^"]+"|'cid:[^']+')/i
+
+    include Base64
+
+    def self.previewing_email(message) #:nodoc:
+      new(message).transform!
+    end
+
+    def initialize(message) #:nodoc:
+      @message = message
+    end
+
+    def transform! #:nodoc:
+      return message if html_part.blank?
+
+      html_source.gsub!(PATTERN) do |match|
+        if part = find_part(match[9..-2])
+          %[src="#{data_url(part)}"]
+        else
+          match
+        end
+      end
+
+      message
+    end
+
+    private
+      def message
+        @message
+      end
+
+      def html_part
+        @html_part ||= message.html_part
+      end
+
+      def html_source
+        html_part.body.raw_source
+      end
+
+      def data_url(part)
+        "data:#{part.mime_type};base64,#{strict_encode64(part.body.raw_source)}"
+      end
+
+      def find_part(cid)
+        message.all_parts.find{ |p| p.attachment? && p.cid == cid }
+      end
+  end
+end
diff --git a/actionmailer/lib/action_mailer/log_subscriber.rb b/actionmailer/lib/action_mailer/log_subscriber.rb
index 5b57c75ec3..7e9d916b66 100644
--- a/actionmailer/lib/action_mailer/log_subscriber.rb
+++ b/actionmailer/lib/action_mailer/log_subscriber.rb
@@ -2,7 +2,7 @@ require 'active_support/log_subscriber'
 
 module ActionMailer
   # Implements the ActiveSupport::LogSubscriber for logging notifications when
-  # email is delivered and received.
+  # email is delivered or received.
   class LogSubscriber < ActiveSupport::LogSubscriber
     # An email was delivered.
     def deliver(event)
@@ -29,7 +29,7 @@ module ActionMailer
       end
     end
 
-    # Use the logger configured for ActionMailer::Base
+    # Use the logger configured for ActionMailer::Base.
     def logger
       ActionMailer::Base.logger
     end
diff --git a/actionmailer/lib/action_mailer/mail_helper.rb b/actionmailer/lib/action_mailer/mail_helper.rb
index cc7935a7e0..239974e7b1 100644
--- a/actionmailer/lib/action_mailer/mail_helper.rb
+++ b/actionmailer/lib/action_mailer/mail_helper.rb
@@ -4,7 +4,17 @@ module ActionMailer
   # attachments list.
   module MailHelper
     # Take the text and format it, indented two spaces for each line, and
-    # wrapped at 72 columns.
+    # wrapped at 72 columns:
+    #
+    #   text = <<-TEXT
+    #     This is
+    #     the      paragraph.
+    #
+    #     * item1 * item2
+    #   TEXT
+    #
+    #   block_format text
+    #   # => "  This is the paragraph.\n\n  * item1\n  * item2\n"
     def block_format(text)
       formatted = text.split(/\n\r?\n/).collect { |paragraph|
         format_paragraph(paragraph)
@@ -33,6 +43,8 @@ module ActionMailer
     end
 
     # Returns +text+ wrapped at +len+ columns and indented +indent+ spaces.
+    # By default column length +len+ equals 72 characters and indent
+    # +indent+ equal two spaces.
     #
     #   my_text = 'Here is a sample text with more than 40 characters'
     #
diff --git a/actionmailer/lib/action_mailer/message_delivery.rb b/actionmailer/lib/action_mailer/message_delivery.rb
index ff2cb0fd01..622d481113 100644
--- a/actionmailer/lib/action_mailer/message_delivery.rb
+++ b/actionmailer/lib/action_mailer/message_delivery.rb
@@ -60,9 +60,9 @@ module ActionMailer
     #
     # Options:
     #
-    # * <tt>:wait</tt> - Enqueue the email to be delivered with a delay
-    # * <tt>:wait_until</tt> - Enqueue the email to be delivered at (after) a specific date / time
-    # * <tt>:queue</tt> - Enqueue the email on the specified queue
+    # * <tt>:wait</tt> - Enqueue the email to be delivered with a delay.
+    # * <tt>:wait_until</tt> - Enqueue the email to be delivered at (after) a specific date / time.
+    # * <tt>:queue</tt> - Enqueue the email on the specified queue.
     def deliver_later(options={})
       enqueue_delivery :deliver_now, options
     end
diff --git a/actionmailer/lib/action_mailer/preview.rb b/actionmailer/lib/action_mailer/preview.rb
index 44cf6665ba..aab92fe8db 100644
--- a/actionmailer/lib/action_mailer/preview.rb
+++ b/actionmailer/lib/action_mailer/preview.rb
@@ -21,7 +21,7 @@ module ActionMailer
 
       # :nodoc:
       mattr_accessor :preview_interceptors, instance_writer: false
-      self.preview_interceptors = []
+      self.preview_interceptors = [ActionMailer::InlinePreviewInterceptor]
     end
 
     module ClassMethods
@@ -52,7 +52,7 @@ module ActionMailer
     extend ActiveSupport::DescendantsTracker
 
     class << self
-      # Returns all mailer preview classes
+      # Returns all mailer preview classes.
       def all
         load_previews if descendants.empty?
         descendants
@@ -68,27 +68,27 @@ module ActionMailer
         message
       end
 
-      # Returns all of the available email previews
+      # Returns all of the available email previews.
       def emails
         public_instance_methods(false).map(&:to_s).sort
       end
 
-      # Returns true if the email exists
+      # Returns true if the email exists.
       def email_exists?(email)
         emails.include?(email)
       end
 
-      # Returns true if the preview exists
+      # Returns true if the preview exists.
       def exists?(preview)
         all.any?{ |p| p.preview_name == preview }
       end
 
-      # Find a mailer preview by its underscored class name
+      # Find a mailer preview by its underscored class name.
       def find(preview)
         all.find{ |p| p.preview_name == preview }
       end
 
-      # Returns the underscored name of the mailer preview without the suffix
+      # Returns the underscored name of the mailer preview without the suffix.
       def preview_name
         name.sub(/Preview$/, '').underscore
       end
diff --git a/actionmailer/lib/action_mailer/railtie.rb b/actionmailer/lib/action_mailer/railtie.rb
index bebcf4de01..fa707021c7 100644
--- a/actionmailer/lib/action_mailer/railtie.rb
+++ b/actionmailer/lib/action_mailer/railtie.rb
@@ -16,6 +16,11 @@ module ActionMailer
       paths   = app.config.paths
       options = app.config.action_mailer
 
+      if app.config.force_ssl
+        options.default_url_options ||= {}
+        options.default_url_options[:protocol] ||= 'https'
+      end
+
       options.assets_dir      ||= paths["public"].first
       options.javascripts_dir ||= paths["public/javascripts"].first
       options.stylesheets_dir ||= paths["public/stylesheets"].first
diff --git a/actionmailer/lib/action_mailer/test_case.rb b/actionmailer/lib/action_mailer/test_case.rb
index 766215ce96..0aa15e31ba 100644
--- a/actionmailer/lib/action_mailer/test_case.rb
+++ b/actionmailer/lib/action_mailer/test_case.rb
@@ -57,28 +57,28 @@ module ActionMailer
 
       protected
 
-        def initialize_test_deliveries
+        def initialize_test_deliveries # :nodoc:
           set_delivery_method :test
           @old_perform_deliveries = ActionMailer::Base.perform_deliveries
           ActionMailer::Base.perform_deliveries = true
         end
 
-        def restore_test_deliveries
+        def restore_test_deliveries # :nodoc:
           restore_delivery_method
           ActionMailer::Base.perform_deliveries = @old_perform_deliveries
           ActionMailer::Base.deliveries.clear
         end
 
-        def set_delivery_method(method)
+        def set_delivery_method(method) # :nodoc:
           @old_delivery_method = ActionMailer::Base.delivery_method
           ActionMailer::Base.delivery_method = method
         end
 
-        def restore_delivery_method
+        def restore_delivery_method # :nodoc:
           ActionMailer::Base.delivery_method = @old_delivery_method
         end
 
-        def set_expected_mail
+        def set_expected_mail # :nodoc:
           @expected = Mail.new
           @expected.content_type ["text", "plain", { "charset" => charset }]
           @expected.mime_version = '1.0'
diff --git a/actionmailer/lib/action_mailer/test_helper.rb b/actionmailer/lib/action_mailer/test_helper.rb
index 524e6e3af1..45cfe16899 100644
--- a/actionmailer/lib/action_mailer/test_helper.rb
+++ b/actionmailer/lib/action_mailer/test_helper.rb
@@ -2,7 +2,7 @@ require 'active_job'
 
 module ActionMailer
   # Provides helper methods for testing Action Mailer, including #assert_emails
-  # and #assert_no_emails
+  # and #assert_no_emails.
   module TestHelper
     include ActiveJob::TestHelper
 
@@ -34,7 +34,7 @@ module ActionMailer
         original_count = ActionMailer::Base.deliveries.size
         yield
         new_count = ActionMailer::Base.deliveries.size
-        assert_equal original_count + number, new_count, "#{number} emails expected, but #{new_count - original_count} were sent"
+        assert_equal number, new_count - original_count, "#{number} emails expected, but #{new_count - original_count} were sent"
       else
         assert_equal number, ActionMailer::Base.deliveries.size
       end
diff --git a/actionmailer/lib/rails/generators/mailer/USAGE b/actionmailer/lib/rails/generators/mailer/USAGE
index d9d9d064d8..2b0a078109 100644
--- a/actionmailer/lib/rails/generators/mailer/USAGE
+++ b/actionmailer/lib/rails/generators/mailer/USAGE
@@ -12,6 +12,6 @@ Example:
 
     creates a Notifications mailer class, views, and test:
         Mailer:     app/mailers/notifications_mailer.rb
-        Views:      app/views/notifications/signup.text.erb [...]
-        Test:       test/mailers/notifications_test.rb
+        Views:      app/views/notifications_mailer/signup.text.erb [...]
+        Test:       test/mailers/notifications_mailer_test.rb
 
diff --git a/actionmailer/test/abstract_unit.rb b/actionmailer/test/abstract_unit.rb
index 7681679dc7..85d3629514 100644
--- a/actionmailer/test/abstract_unit.rb
+++ b/actionmailer/test/abstract_unit.rb
@@ -9,13 +9,13 @@ silence_warnings do
 end
 
 require 'active_support/testing/autorun'
+require 'active_support/testing/method_call_assertions'
 require 'action_mailer'
 require 'action_mailer/test_case'
-require 'mail'
 
 # Emulate AV railtie
 require 'action_view'
-ActionMailer::Base.send(:include, ActionView::Layouts)
+ActionMailer::Base.include(ActionView::Layouts)
 
 # Show backtraces for deprecated behavior for quicker cleanup.
 ActiveSupport::Deprecation.debug = true
@@ -41,9 +41,6 @@ def jruby_skip(message = '')
   skip message if defined?(JRUBY_VERSION)
 end
 
-require 'mocha/setup' # FIXME: stop using mocha
-
-# FIXME: we have tests that depend on run order, we should fix that and
-# remove this method call.
-require 'active_support/test_case'
-ActiveSupport::TestCase.test_order = :sorted
+class ActiveSupport::TestCase
+  include ActiveSupport::Testing::MethodCallAssertions
+end
diff --git a/actionmailer/test/base_test.rb b/actionmailer/test/base_test.rb
index b218d923e5..50f2c71737 100644
--- a/actionmailer/test/base_test.rb
+++ b/actionmailer/test/base_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'set'
 
@@ -450,6 +449,13 @@ class BaseTest < ActiveSupport::TestCase
     assert_equal("Format with any!", email.parts[1].body.encoded)
   end
 
+  test 'explicit without specifying format with format.any' do
+    error = assert_raises(ArgumentError) do
+      BaseMailer.explicit_without_specifying_format_with_any.parts
+    end
+    assert_equal "You have to supply at least one format", error.message
+  end
+
   test "explicit multipart with format(Hash)" do
     email = BaseMailer.explicit_multipart_with_options(true)
     email.ready_to_send!
@@ -506,9 +512,10 @@ class BaseTest < ActiveSupport::TestCase
   end
 
   test "calling deliver on the action should deliver the mail object" do
-    BaseMailer.expects(:deliver_mail).once
-    mail = BaseMailer.welcome.deliver_now
-    assert_equal 'The first email on new API!', mail.subject
+    assert_called(BaseMailer, :deliver_mail) do
+      mail = BaseMailer.welcome.deliver_now
+      assert_equal 'The first email on new API!', mail.subject
+    end
   end
 
   test "calling deliver on the action should increment the deliveries collection if using the test mailer" do
@@ -518,9 +525,11 @@ class BaseTest < ActiveSupport::TestCase
 
   test "calling deliver, ActionMailer should yield back to mail to let it call :do_delivery on itself" do
     mail = Mail::Message.new
-    mail.expects(:do_delivery).once
-    BaseMailer.expects(:welcome).returns(mail)
-    BaseMailer.welcome.deliver
+    assert_called(mail, :do_delivery) do
+      assert_called(BaseMailer, :welcome, returns: mail) do
+        BaseMailer.welcome.deliver
+      end
+    end
   end
 
   # Rendering
@@ -608,8 +617,9 @@ class BaseTest < ActiveSupport::TestCase
     mail_side_effects do
       ActionMailer::Base.register_observer(MyObserver)
       mail = BaseMailer.welcome
-      MyObserver.expects(:delivered_email).with(mail)
-      mail.deliver_now
+      assert_called_with(MyObserver, :delivered_email, [mail]) do
+        mail.deliver_now
+      end
     end
   end
 
@@ -617,8 +627,9 @@ class BaseTest < ActiveSupport::TestCase
     mail_side_effects do
       ActionMailer::Base.register_observer("BaseTest::MyObserver")
       mail = BaseMailer.welcome
-      MyObserver.expects(:delivered_email).with(mail)
-      mail.deliver_now
+      assert_called_with(MyObserver, :delivered_email, [mail]) do
+        mail.deliver_now
+      end
     end
   end
 
@@ -626,8 +637,9 @@ class BaseTest < ActiveSupport::TestCase
     mail_side_effects do
       ActionMailer::Base.register_observer(:"base_test/my_observer")
       mail = BaseMailer.welcome
-      MyObserver.expects(:delivered_email).with(mail)
-      mail.deliver_now
+      assert_called_with(MyObserver, :delivered_email, [mail]) do
+        mail.deliver_now
+      end
     end
   end
 
@@ -635,9 +647,11 @@ class BaseTest < ActiveSupport::TestCase
     mail_side_effects do
       ActionMailer::Base.register_observers("BaseTest::MyObserver", MySecondObserver)
       mail = BaseMailer.welcome
-      MyObserver.expects(:delivered_email).with(mail)
-      MySecondObserver.expects(:delivered_email).with(mail)
-      mail.deliver_now
+      assert_called_with(MyObserver, :delivered_email, [mail]) do
+        assert_called_with(MySecondObserver, :delivered_email, [mail]) do
+          mail.deliver_now
+        end
+      end
     end
   end
 
@@ -655,8 +669,9 @@ class BaseTest < ActiveSupport::TestCase
     mail_side_effects do
       ActionMailer::Base.register_interceptor(MyInterceptor)
       mail = BaseMailer.welcome
-      MyInterceptor.expects(:delivering_email).with(mail)
-      mail.deliver_now
+      assert_called_with(MyInterceptor, :delivering_email, [mail]) do
+        mail.deliver_now
+      end
     end
   end
 
@@ -664,8 +679,9 @@ class BaseTest < ActiveSupport::TestCase
     mail_side_effects do
       ActionMailer::Base.register_interceptor("BaseTest::MyInterceptor")
       mail = BaseMailer.welcome
-      MyInterceptor.expects(:delivering_email).with(mail)
-      mail.deliver_now
+      assert_called_with(MyInterceptor, :delivering_email, [mail]) do
+        mail.deliver_now
+      end
     end
   end
 
@@ -673,8 +689,9 @@ class BaseTest < ActiveSupport::TestCase
     mail_side_effects do
       ActionMailer::Base.register_interceptor(:"base_test/my_interceptor")
       mail = BaseMailer.welcome
-      MyInterceptor.expects(:delivering_email).with(mail)
-      mail.deliver_now
+      assert_called_with(MyInterceptor, :delivering_email, [mail]) do
+        mail.deliver_now
+      end
     end
   end
 
@@ -682,18 +699,21 @@ class BaseTest < ActiveSupport::TestCase
     mail_side_effects do
       ActionMailer::Base.register_interceptors("BaseTest::MyInterceptor", MySecondInterceptor)
       mail = BaseMailer.welcome
-      MyInterceptor.expects(:delivering_email).with(mail)
-      MySecondInterceptor.expects(:delivering_email).with(mail)
-      mail.deliver_now
+      assert_called_with(MyInterceptor, :delivering_email, [mail]) do
+        assert_called_with(MySecondInterceptor, :delivering_email, [mail]) do
+          mail.deliver_now
+        end
+      end
     end
   end
 
   test "being able to put proc's into the defaults hash and they get evaluated on mail sending" do
     mail1 = ProcMailer.welcome['X-Proc-Method']
     yesterday = 1.day.ago
-    Time.stubs(:now).returns(yesterday)
-    mail2 = ProcMailer.welcome['X-Proc-Method']
-    assert(mail1.to_s.to_i > mail2.to_s.to_i)
+    Time.stub(:now, yesterday) do
+      mail2 = ProcMailer.welcome['X-Proc-Method']
+      assert(mail1.to_s.to_i > mail2.to_s.to_i)
+    end
   end
 
   test 'default values which have to_proc (e.g. symbols) should not be considered procs' do
@@ -878,33 +898,50 @@ class BasePreviewInterceptorsTest < ActiveSupport::TestCase
   test "you can register a preview interceptor to the mail object that gets passed the mail object before previewing" do
     ActionMailer::Base.register_preview_interceptor(MyInterceptor)
     mail = BaseMailer.welcome
-    BaseMailerPreview.any_instance.stubs(:welcome).returns(mail)
-    MyInterceptor.expects(:previewing_email).with(mail)
-    BaseMailerPreview.call(:welcome)
+    stub_any_instance(BaseMailerPreview) do |instance|
+      instance.stub(:welcome, mail) do
+        assert_called_with(MyInterceptor, :previewing_email, [mail]) do
+          BaseMailerPreview.call(:welcome)
+        end
+      end
+    end
   end
 
   test "you can register a preview interceptor using its stringified name to the mail object that gets passed the mail object before previewing" do
     ActionMailer::Base.register_preview_interceptor("BasePreviewInterceptorsTest::MyInterceptor")
     mail = BaseMailer.welcome
-    BaseMailerPreview.any_instance.stubs(:welcome).returns(mail)
-    MyInterceptor.expects(:previewing_email).with(mail)
-    BaseMailerPreview.call(:welcome)
+    stub_any_instance(BaseMailerPreview) do |instance|
+      instance.stub(:welcome, mail) do
+        assert_called_with(MyInterceptor, :previewing_email, [mail]) do
+          BaseMailerPreview.call(:welcome)
+        end
+      end
+    end
   end
 
   test "you can register an interceptor using its symbolized underscored name to the mail object that gets passed the mail object before previewing" do
     ActionMailer::Base.register_preview_interceptor(:"base_preview_interceptors_test/my_interceptor")
     mail = BaseMailer.welcome
-    BaseMailerPreview.any_instance.stubs(:welcome).returns(mail)
-    MyInterceptor.expects(:previewing_email).with(mail)
-    BaseMailerPreview.call(:welcome)
+    stub_any_instance(BaseMailerPreview) do |instance|
+      instance.stub(:welcome, mail) do
+        assert_called_with(MyInterceptor, :previewing_email, [mail]) do
+          BaseMailerPreview.call(:welcome)
+        end
+      end
+    end
   end
 
   test "you can register multiple preview interceptors to the mail object that both get passed the mail object before previewing" do
     ActionMailer::Base.register_preview_interceptors("BasePreviewInterceptorsTest::MyInterceptor", MySecondInterceptor)
     mail = BaseMailer.welcome
-    BaseMailerPreview.any_instance.stubs(:welcome).returns(mail)
-    MyInterceptor.expects(:previewing_email).with(mail)
-    MySecondInterceptor.expects(:previewing_email).with(mail)
-    BaseMailerPreview.call(:welcome)
+    stub_any_instance(BaseMailerPreview) do |instance|
+      instance.stub(:welcome, mail) do
+        assert_called_with(MyInterceptor, :previewing_email, [mail]) do
+          assert_called_with(MySecondInterceptor, :previewing_email, [mail]) do
+            BaseMailerPreview.call(:welcome)
+          end
+        end
+      end
+    end
   end
 end
diff --git a/actionmailer/test/delivery_methods_test.rb b/actionmailer/test/delivery_methods_test.rb
index 2e4e019bf7..d17e774092 100644
--- a/actionmailer/test/delivery_methods_test.rb
+++ b/actionmailer/test/delivery_methods_test.rb
@@ -1,5 +1,4 @@
 require 'abstract_unit'
-require 'mail'
 
 class MyCustomDelivery
 end
@@ -103,16 +102,21 @@ class MailDeliveryTest < ActiveSupport::TestCase
   end
 
   test "ActionMailer should be told when Mail gets delivered" do
-    DeliveryMailer.expects(:deliver_mail).once
-    DeliveryMailer.welcome.deliver_now
+    DeliveryMailer.delivery_method = :test
+    assert_called(DeliveryMailer, :deliver_mail) do
+      DeliveryMailer.welcome.deliver_now
+    end
   end
 
   test "delivery method can be customized per instance" do
-    Mail::SMTP.any_instance.expects(:deliver!)
-    email = DeliveryMailer.welcome.deliver_now
-    assert_instance_of Mail::SMTP, email.delivery_method
-    email = DeliveryMailer.welcome(delivery_method: :test).deliver_now
-    assert_instance_of Mail::TestMailer, email.delivery_method
+    stub_any_instance(Mail::SMTP, instance: Mail::SMTP.new({})) do |instance|
+      assert_called(instance, :deliver!) do
+        email = DeliveryMailer.welcome.deliver_now
+        assert_instance_of Mail::SMTP, email.delivery_method
+        email = DeliveryMailer.welcome(delivery_method: :test).deliver_now
+        assert_instance_of Mail::TestMailer, email.delivery_method
+      end
+    end
   end
 
   test "delivery method can be customized in subclasses not changing the parent" do
@@ -161,24 +165,29 @@ class MailDeliveryTest < ActiveSupport::TestCase
 
   test "non registered delivery methods raises errors" do
     DeliveryMailer.delivery_method = :unknown
-    assert_raise RuntimeError do
+    error = assert_raise RuntimeError do
       DeliveryMailer.welcome.deliver_now
     end
+    assert_equal "Invalid delivery method :unknown", error.message
   end
 
   test "undefined delivery methods raises errors" do
     DeliveryMailer.delivery_method = nil
-    assert_raise RuntimeError do
+    error = assert_raise RuntimeError do
       DeliveryMailer.welcome.deliver_now
     end
+    assert_equal "Delivery method cannot be nil", error.message
   end
 
   test "does not perform deliveries if requested" do
     old_perform_deliveries = DeliveryMailer.perform_deliveries
     begin
       DeliveryMailer.perform_deliveries = false
-      Mail::Message.any_instance.expects(:deliver!).never
-      DeliveryMailer.welcome.deliver_now
+      stub_any_instance(Mail::Message) do |instance|
+        assert_not_called(instance, :deliver!) do
+          DeliveryMailer.welcome.deliver_now
+        end
+      end
     ensure
       DeliveryMailer.perform_deliveries = old_perform_deliveries
     end
diff --git a/actionmailer/test/fixtures/base_mailer/email_custom_layout.text.html.erb b/actionmailer/test/fixtures/base_mailer/email_custom_layout.text.html.erb
deleted file mode 100644
index a2187308b6..0000000000
--- a/actionmailer/test/fixtures/base_mailer/email_custom_layout.text.html.erb
+++ /dev/null
@@ -1 +0,0 @@
-body_text
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/first_mailer/share.erb b/actionmailer/test/fixtures/first_mailer/share.erb
deleted file mode 100644
index da43638ceb..0000000000
--- a/actionmailer/test/fixtures/first_mailer/share.erb
+++ /dev/null
@@ -1 +0,0 @@
-first mail
diff --git a/actionmailer/test/fixtures/path.with.dots/funky_path_mailer/multipart_with_template_path_with_dots.erb b/actionmailer/test/fixtures/path.with.dots/funky_path_mailer/multipart_with_template_path_with_dots.erb
deleted file mode 100644
index 2d0cd5c124..0000000000
--- a/actionmailer/test/fixtures/path.with.dots/funky_path_mailer/multipart_with_template_path_with_dots.erb
+++ /dev/null
@@ -1 +0,0 @@
-Have some dots. Enjoy!
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/second_mailer/share.erb b/actionmailer/test/fixtures/second_mailer/share.erb
deleted file mode 100644
index 9a54010672..0000000000
--- a/actionmailer/test/fixtures/second_mailer/share.erb
+++ /dev/null
@@ -1 +0,0 @@
-second mail
diff --git a/actionmailer/test/fixtures/test_mailer/_subtemplate.text.erb b/actionmailer/test/fixtures/test_mailer/_subtemplate.text.erb
deleted file mode 100644
index 3b4ba35f20..0000000000
--- a/actionmailer/test/fixtures/test_mailer/_subtemplate.text.erb
+++ /dev/null
@@ -1 +0,0 @@
-let's go!
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/test_mailer/custom_templating_extension.html.haml b/actionmailer/test/fixtures/test_mailer/custom_templating_extension.html.haml
deleted file mode 100644
index 8dcf9746cc..0000000000
--- a/actionmailer/test/fixtures/test_mailer/custom_templating_extension.html.haml
+++ /dev/null
@@ -1,6 +0,0 @@
-%p Hello there,
-
-%p
-  Mr.
-  = @recipient
-  from haml
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/test_mailer/custom_templating_extension.text.haml b/actionmailer/test/fixtures/test_mailer/custom_templating_extension.text.haml
deleted file mode 100644
index 8dcf9746cc..0000000000
--- a/actionmailer/test/fixtures/test_mailer/custom_templating_extension.text.haml
+++ /dev/null
@@ -1,6 +0,0 @@
-%p Hello there,
-
-%p
-  Mr.
-  = @recipient
-  from haml
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.html.erb b/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.html.erb
deleted file mode 100644
index 946d99ede5..0000000000
--- a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.html.erb
+++ /dev/null
@@ -1,10 +0,0 @@
-<html>
-  <body>
-    HTML formatted message to <strong><%= @recipient %></strong>.
-  </body>
-</html>
-<html>
-  <body>
-    HTML formatted message to <strong><%= @recipient %></strong>.
-  </body>
-</html>
diff --git a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.html.erb~ b/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.html.erb~
deleted file mode 100644
index 946d99ede5..0000000000
--- a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.html.erb~
+++ /dev/null
@@ -1,10 +0,0 @@
-<html>
-  <body>
-    HTML formatted message to <strong><%= @recipient %></strong>.
-  </body>
-</html>
-<html>
-  <body>
-    HTML formatted message to <strong><%= @recipient %></strong>.
-  </body>
-</html>
diff --git a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.ignored.erb b/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.ignored.erb
deleted file mode 100644
index 6940419d47..0000000000
--- a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.ignored.erb
+++ /dev/null
@@ -1 +0,0 @@
-Ignored when searching for implicitly multipart parts.
diff --git a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.rhtml.bak b/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.rhtml.bak
deleted file mode 100644
index 6940419d47..0000000000
--- a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.rhtml.bak
+++ /dev/null
@@ -1 +0,0 @@
-Ignored when searching for implicitly multipart parts.
diff --git a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.text.erb b/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.text.erb
deleted file mode 100644
index a6c8d54cf9..0000000000
--- a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.text.erb
+++ /dev/null
@@ -1,2 +0,0 @@
-Plain text to <%= @recipient %>.
-Plain text to <%= @recipient %>.
diff --git a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.yaml.erb b/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.yaml.erb
deleted file mode 100644
index c14348c770..0000000000
--- a/actionmailer/test/fixtures/test_mailer/implicitly_multipart_example.yaml.erb
+++ /dev/null
@@ -1 +0,0 @@
-yaml to: <%= @recipient %>
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/test_mailer/included_subtemplate.text.erb b/actionmailer/test/fixtures/test_mailer/included_subtemplate.text.erb
deleted file mode 100644
index ae3cfa77e7..0000000000
--- a/actionmailer/test/fixtures/test_mailer/included_subtemplate.text.erb
+++ /dev/null
@@ -1 +0,0 @@
-Hey Ho, <%= render partial: "subtemplate" %>
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/test_mailer/multipart_alternative.html.erb b/actionmailer/test/fixtures/test_mailer/multipart_alternative.html.erb
deleted file mode 100644
index 73ea14f82f..0000000000
--- a/actionmailer/test/fixtures/test_mailer/multipart_alternative.html.erb
+++ /dev/null
@@ -1 +0,0 @@
-<strong>foo</strong> <%= @foo %>
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/test_mailer/multipart_alternative.plain.erb b/actionmailer/test/fixtures/test_mailer/multipart_alternative.plain.erb
deleted file mode 100644
index 779fe4c1ea..0000000000
--- a/actionmailer/test/fixtures/test_mailer/multipart_alternative.plain.erb
+++ /dev/null
@@ -1 +0,0 @@
-foo: <%= @foo %>
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/test_mailer/rxml_template.rxml b/actionmailer/test/fixtures/test_mailer/rxml_template.rxml
deleted file mode 100644
index d566bd8d7c..0000000000
--- a/actionmailer/test/fixtures/test_mailer/rxml_template.rxml
+++ /dev/null
@@ -1,2 +0,0 @@
-xml.instruct!
-xml.test
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/test_mailer/signed_up.html.erb b/actionmailer/test/fixtures/test_mailer/signed_up.html.erb
deleted file mode 100644
index 7afe1f651c..0000000000
--- a/actionmailer/test/fixtures/test_mailer/signed_up.html.erb
+++ /dev/null
@@ -1,3 +0,0 @@
-Hello there,
-
-Mr. <%= @recipient %>
\ No newline at end of file
diff --git a/actionmailer/test/i18n_with_controller_test.rb b/actionmailer/test/i18n_with_controller_test.rb
index 010e44d045..6124ffeb52 100644
--- a/actionmailer/test/i18n_with_controller_test.rb
+++ b/actionmailer/test/i18n_with_controller_test.rb
@@ -52,10 +52,15 @@ class ActionMailerI18nWithControllerTest < ActionDispatch::IntegrationTest
   end
 
   def test_send_mail
-    Mail::SMTP.any_instance.expects(:deliver!)
-    with_translation 'de', email_subject: '[Anmeldung] Willkommen' do
-      get '/test/send_mail'
-      assert_equal "Mail sent - Subject: [Anmeldung] Willkommen", @response.body
+    stub_any_instance(Mail::SMTP, instance: Mail::SMTP.new({})) do |instance|
+      assert_called(instance, :deliver!) do
+        with_translation 'de', email_subject: '[Anmeldung] Willkommen' do
+          ActiveSupport::Deprecation.silence do
+            get '/test/send_mail'
+          end
+          assert_equal "Mail sent - Subject: [Anmeldung] Willkommen", @response.body
+        end
+      end
     end
   end
 
diff --git a/actionmailer/test/mail_helper_test.rb b/actionmailer/test/mail_helper_test.rb
index 24ccaab8df..ff6b25b0c7 100644
--- a/actionmailer/test/mail_helper_test.rb
+++ b/actionmailer/test/mail_helper_test.rb
@@ -59,6 +59,12 @@ The second
     end
   end
 
+  def use_cache
+    mail_with_defaults do |format|
+      format.html { render(inline: "<% cache(:foo) do %>Greetings from a cache helper block<% end %>") }
+    end
+  end
+
   protected
 
   def mail_with_defaults(&block)
@@ -107,5 +113,11 @@ class MailerHelperTest < ActionMailer::TestCase
     TEXT
     assert_equal expected.gsub("\n", "\r\n"), mail.body.encoded
   end
-end
 
+  def test_use_cache
+    assert_nothing_raised do
+      mail = HelperMailer.use_cache
+      assert_equal "Greetings from a cache helper block", mail.body.encoded
+    end
+  end
+end
diff --git a/actionmailer/test/mailers/base_mailer.rb b/actionmailer/test/mailers/base_mailer.rb
index bd991e209e..8c2225ce60 100644
--- a/actionmailer/test/mailers/base_mailer.rb
+++ b/actionmailer/test/mailers/base_mailer.rb
@@ -80,6 +80,12 @@ class BaseMailer < ActionMailer::Base
     end
   end
 
+  def explicit_without_specifying_format_with_any(hash = {})
+    mail(hash) do |format|
+      format.any
+    end
+  end
+
   def explicit_multipart_with_options(include_html = false)
     mail do |format|
       format.text(content_transfer_encoding: "base64"){ render "welcome" }
diff --git a/actionmailer/test/message_delivery_test.rb b/actionmailer/test/message_delivery_test.rb
index 55ee00602a..b834cdd08c 100644
--- a/actionmailer/test/message_delivery_test.rb
+++ b/actionmailer/test/message_delivery_test.rb
@@ -1,9 +1,6 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'active_job'
-require 'minitest/mock'
 require 'mailers/delayed_mailer'
-require 'active_support/core_ext/numeric/time'
 
 class MessageDeliveryTest < ActiveSupport::TestCase
   include ActiveJob::TestHelper
@@ -11,6 +8,8 @@ class MessageDeliveryTest < ActiveSupport::TestCase
   setup do
     @previous_logger = ActiveJob::Base.logger
     @previous_delivery_method = ActionMailer::Base.delivery_method
+    @previous_deliver_later_queue_name = ActionMailer::Base.deliver_later_queue_name
+    ActionMailer::Base.deliver_later_queue_name = :test_queue
     ActionMailer::Base.delivery_method = :test
     ActiveJob::Base.logger = Logger.new(nil)
     @mail = DelayedMailer.test_message(1, 2, 3)
@@ -22,6 +21,7 @@ class MessageDeliveryTest < ActiveSupport::TestCase
   teardown do
     ActiveJob::Base.logger = @previous_logger
     ActionMailer::Base.delivery_method = @previous_delivery_method
+    ActionMailer::Base.deliver_later_queue_name = @previous_deliver_later_queue_name
   end
 
   test 'should have a message' do
@@ -82,4 +82,15 @@ class MessageDeliveryTest < ActiveSupport::TestCase
     end
   end
 
+  test 'should enqueue the job on the correct queue' do
+    assert_performed_with(job: ActionMailer::DeliveryJob, args: ['DelayedMailer', 'test_message', 'deliver_now', 1, 2, 3], queue: "test_queue") do
+      @mail.deliver_later
+    end
+  end
+
+  test 'can override the queue when enqueuing mail' do
+    assert_performed_with(job: ActionMailer::DeliveryJob, args: ['DelayedMailer', 'test_message', 'deliver_now', 1, 2, 3], queue: "another_queue") do
+      @mail.deliver_later(queue: :another_queue)
+    end
+  end
 end
diff --git a/actionmailer/test/test_helper_test.rb b/actionmailer/test/test_helper_test.rb
index 21e7154c43..0a4bc75d3e 100644
--- a/actionmailer/test/test_helper_test.rb
+++ b/actionmailer/test/test_helper_test.rb
@@ -1,5 +1,5 @@
-# encoding: utf-8
 require 'abstract_unit'
+require 'active_support/testing/stream'
 
 class TestHelperMailer < ActionMailer::Base
   def test
@@ -11,6 +11,8 @@ class TestHelperMailer < ActionMailer::Base
 end
 
 class TestHelperMailerTest < ActionMailer::TestCase
+  include ActiveSupport::Testing::Stream
+
   def test_setup_sets_right_action_mailer_options
     assert_equal :test, ActionMailer::Base.delivery_method
     assert ActionMailer::Base.perform_deliveries
@@ -110,6 +112,17 @@ class TestHelperMailerTest < ActionMailer::TestCase
     assert_match(/1 .* but 2/, error.message)
   end
 
+  def test_assert_emails_message
+    TestHelperMailer.test.deliver_now
+    error = assert_raise ActiveSupport::TestCase::Assertion do
+      assert_emails 2 do
+        TestHelperMailer.test.deliver_now
+      end
+    end
+    assert_match "Expected: 2", error.message
+    assert_match "Actual: 1", error.message
+  end
+
   def test_assert_no_emails_failure
     error = assert_raise ActiveSupport::TestCase::Assertion do
       assert_no_emails do
@@ -123,7 +136,9 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_assert_enqueued_emails
     assert_nothing_raised do
       assert_enqueued_emails 1 do
-        TestHelperMailer.test.deliver_later
+        silence_stream($stdout) do
+          TestHelperMailer.test.deliver_later
+        end
       end
     end
   end
@@ -131,7 +146,9 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_assert_enqueued_emails_too_few_sent
     error = assert_raise ActiveSupport::TestCase::Assertion do
       assert_enqueued_emails 2 do
-        TestHelperMailer.test.deliver_later
+        silence_stream($stdout) do
+          TestHelperMailer.test.deliver_later
+        end
       end
     end
 
@@ -141,8 +158,10 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_assert_enqueued_emails_too_many_sent
     error = assert_raise ActiveSupport::TestCase::Assertion do
       assert_enqueued_emails 1 do
-        TestHelperMailer.test.deliver_later
-        TestHelperMailer.test.deliver_later
+        silence_stream($stdout) do
+          TestHelperMailer.test.deliver_later
+          TestHelperMailer.test.deliver_later
+        end
       end
     end
 
@@ -160,7 +179,9 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_assert_no_enqueued_emails_failure
     error = assert_raise ActiveSupport::TestCase::Assertion do
       assert_no_enqueued_emails do
-        TestHelperMailer.test.deliver_later
+        silence_stream($stdout) do
+          TestHelperMailer.test.deliver_later
+        end
       end
     end
 
diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 6cd0b2d15d..4f95a9bab9 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,15 +1,429 @@
+*   Catch invalid UTF-8 querystring values and respond with BadRequest
+
+    Check querystring params for invalid UTF-8 characters, and raise an
+    ActionController::BadRequest error if present. Previously these strings
+    would typically trigger errors further down the stack.
+
+    *Grey Baker*
+
+*   Parse RSS/ATOM responses as XML, not HTML.
+
+    *Alexander Kaupanin*
+
+*   Show helpful message in `BadRequest` exceptions due to invalid path
+    parameter encodings.
+
+    Fixes #21923.
+
+    *Agis Anastasopoulos*
+
+*   Deprecate `config.static_cache_control` in favor of
+    `config.public_file_server.headers`
+
+    *Yuki Nishijima*
+
+*   Add the ability of returning arbitrary headers to ActionDispatch::Static
+
+    Now ActionDispatch::Static can accept HTTP headers so that developers
+    will have control of returning arbitrary headers like
+    'Access-Control-Allow-Origin' when a response is delivered. They can be
+    configured with `#config`:
+
+      config.public_file_server.headers = {
+        "Cache-Control"               => "public, max-age=60",
+        "Access-Control-Allow-Origin" => "http://rubyonrails.org"
+      }
+
+    *Yuki Nishijima*
+
+*   Allow multiple `root` routes in same scope level. Example:
+
+    ```ruby
+    root 'blog#show', constraints: ->(req) { Hostname.blog_site?(req.host) }
+    root 'landing#show'
+    ```
+    *Rafael Sales*
+
+*   Fix regression in mounted engine named routes generation for app deployed to
+    a subdirectory. `relative_url_root` was prepended to the path twice (e.g.
+    "/subdir/subdir/engine_path" instead of "/subdir/engine_path")
+
+    Fixes #20920. Fixes #21459.
+
+    *Matthew Erhard*
+
+*   ActionDispatch::Response#new no longer applies default headers.  If you want
+    default headers applied to the response object, then call
+    `ActionDispatch::Response.create`.  This change only impacts people who are
+    directly constructing an `ActionDispatch::Response` object.
+
+*   Accessing mime types via constants like `Mime::HTML` is deprecated.  Please
+    change code like this:
+
+      Mime::HTML
+
+    To this:
+
+      Mime[:html]
+
+    This change is so that Rails will not manage a list of constants, and fixes
+    an issue where if a type isn't registered you could possibly get the wrong
+    object.
+
+    `Mime[:html]` is available in older versions of Rails, too, so you can
+    safely change libraries and plugins and maintain compatibility with
+    multiple versions of Rails.
+
+*   `url_for` does not modify its arguments when generating polymorphic URLs.
+
+    *Bernerd Schaefer*
+
+*   Make it easier to opt in to `config.force_ssl` and `config.ssl_options` by
+    making them less dangerous to try and easier to disable.
+
+    SSL redirect:
+      * Move `:host` and `:port` options within `redirect: { … }`. Deprecate.
+      * Introduce `:status` and `:body` to customize the redirect response.
+        The 301 permanent default makes it difficult to test the redirect and
+        back out of it since browsers remember the 301. Test with a 302 or 307
+        instead, then switch to 301 once you're confident that all is well.
+
+    HTTP Strict Transport Security (HSTS):
+      * Shorter max-age. Shorten the default max-age from 1 year to 180 days,
+        the low end for https://www.ssllabs.com/ssltest/ grading and greater
+        than the 18-week minimum to qualify for browser preload lists.
+      * Disabling HSTS. Setting `hsts: false` now sets `hsts { expires: 0 }`
+        instead of omitting the header. Omitting does nothing to disable HSTS
+        since browsers hang on to your previous settings until they expire.
+        Sending `{ hsts: { expires: 0 }}` flushes out old browser settings and
+        actually disables HSTS:
+          http://tools.ietf.org/html/rfc6797#section-6.1.1
+      * HSTS Preload. Introduce `preload: true` to set the `preload` flag,
+        indicating that your site may be included in browser preload lists,
+        including Chrome, Firefox, Safari, IE11, and Edge. Submit your site:
+          https://hstspreload.appspot.com
+
+    *Jeremy Daer*
+
+*   Update `ActionController::TestSession#fetch` to behave more like
+    `ActionDispatch::Request::Session#fetch` when using non-string keys.
+
+    *Jeremy Friesen*
+
+*   Using strings or symbols for middleware class names is deprecated.  Convert
+    things like this:
+
+      middleware.use "Foo::Bar"
+
+    to this:
+
+      middleware.use Foo::Bar
+
+*   ActionController::TestSession now accepts a default value as well as
+    a block for generating a default value based off the key provided.
+
+    This fixes calls to session#fetch in ApplicationController instances that
+    take more two arguments or a block from raising `ArgumentError: wrong
+    number of arguments (2 for 1)` when performing controller tests.
+
+    *Matthew Gerrior*
+
+*   Fix `ActionController::Parameters#fetch` overwriting `KeyError` returned by
+    default block.
+
+    *Jonas Schuber Erlandsson*, *Roque Pinel*
+
+*   `ActionController::Parameters` no longer inherits from
+    `HashWithIndifferentAccess`
+
+    Inheriting from `HashWithIndifferentAccess` allowed users to call any
+    enumerable methods on `Parameters` object, resulting in a risk of losing the
+    `permitted?` status or even getting back a pure `Hash` object instead of
+    a `Parameters` object with proper sanitization.
+
+    By not inheriting from `HashWithIndifferentAccess`, we are able to make
+    sure that all methods that are defined in `Parameters` object will return
+    a proper `Parameters` object with a correct `permitted?` flag.
+
+    *Prem Sichanugrist*
+
+*   Replaced `ActiveSupport::Concurrency::Latch` with `Concurrent::CountDownLatch`
+    from the concurrent-ruby gem.
+
+    *Jerry D'Antonio*
+
+*   Add ability to filter parameters based on parent keys.
+
+        # matches {credit_card: {code: "xxxx"}}
+        # doesn't match {file: { code: "xxxx"}}
+        config.filter_parameters += [ "credit_card.code" ]
+
+    See #13897.
+
+    *Guillaume Malette*
+
+*   Deprecate passing first parameter as `Hash` and default status code for `head` method.
+
+    *Mehmet Emin İNAÇ*
+
+*   Adds`Rack::Utils::ParameterTypeError` and `Rack::Utils::InvalidParameterError`
+    to the rescue_responses hash in `ExceptionWrapper` (Rack recommends
+    integrators serve 400s for both of these).
+
+    *Grey Baker*
+
+*   Add support for API only apps.
+    ActionController::API is added as a replacement of
+    ActionController::Base for this kind of applications.
+
+    *Santiago Pastorino & Jorge Bejar*
+
+*   Remove `assigns` and `assert_template`. Both methods have been extracted
+    into a gem at https://github.com/rails/rails-controller-testing.
+
+    See #18950.
+
+    *Alan Guo Xiang Tan*
+
+*   `FileHandler` and `Static` middleware initializers accept `index` argument
+    to configure the directory index file name. Defaults to `index` (as in
+    `index.html`).
+
+    See #20017.
+
+    *Eliot Sykes*
+
+*   Deprecate `:nothing` option for `render` method.
+
+    *Mehmet Emin İNAÇ*
+
+*   Fix `rake routes` not showing the right format when
+    nesting multiple routes.
+
+    See #18373.
+
+    *Ravil Bayramgalin*
+
+*   Add ability to override default form builder for a controller.
+
+        class AdminController < ApplicationController
+          default_form_builder AdminFormBuilder
+        end
+
+    *Kevin McPhillips*
+
+*   For actions with no corresponding templates, render `head :no_content`
+    instead of raising an error. This allows for slimmer API controller
+    methods that simply work, without needing further instructions.
+
+    See #19036.
+
+    *Stephen Bussey*
+
+*   Provide friendlier access to request variants.
+
+        request.variant = :phone
+        request.variant.phone?  # true
+        request.variant.tablet? # false
+
+        request.variant = [:phone, :tablet]
+        request.variant.phone?                  # true
+        request.variant.desktop?                # false
+        request.variant.any?(:phone, :desktop)  # true
+        request.variant.any?(:desktop, :watch)  # false
+
+    *George Claghorn*
+
+*   Fix regression where a gzip file response would have a Content-type,
+    even when it was a 304 status code.
+
+    See #19271.
+
+    *Kohei Suzuki*
+
+*   Fix handling of empty `X_FORWARDED_HOST` header in `raw_host_with_port`.
+
+    Previously, an empty `X_FORWARDED_HOST` header would cause
+    `Actiondispatch::Http:URL.raw_host_with_port` to return `nil`, causing
+    `Actiondispatch::Http:URL.host` to raise a `NoMethodError`.
+
+    *Adam Forsyth*
+
+*   Allow `Bearer` as token-keyword in `Authorization-Header`.
+
+    Aditionally to `Token`, the keyword `Bearer` is acceptable as a keyword
+    for the auth-token. The `Bearer` keyword is described in the original
+    OAuth RFC and used in libraries like Angular-JWT.
+
+    See #19094.
+
+    *Peter Schröder*
+
+*   Drop request class from RouteSet constructor.
+
+    If you would like to use a custom request class, please subclass and implement
+    the `request_class` method.
+
+    *tenderlove@ruby-lang.org*
+
+*   Fallback to `ENV['RAILS_RELATIVE_URL_ROOT']` in `url_for`.
+
+    Fixed an issue where the `RAILS_RELATIVE_URL_ROOT` environment variable is not
+    prepended to the path when `url_for` is called. If `SCRIPT_NAME` (used by Rack)
+    is set, it takes precedence.
+
+    Fixes #5122.
+
+    *Yasyf Mohamedali*
+
+*   Partitioning of routes is now done when the routes are being drawn. This
+    helps to decrease the time spent filtering the routes during the first request.
+
+    *Guo Xiang Tan*
+
+*   Fix regression in functional tests. Responses should have default headers
+    assigned.
+
+    See #18423.
+
+    *Jeremy Kemper*, *Yves Senn*
+
+*   Deprecate AbstractController#skip_action_callback in favor of individual skip_callback methods
+    (which can be made to raise an error if no callback was removed).
+
+    *Iain Beeston*
+
+*   Alias the `ActionDispatch::Request#uuid` method to `ActionDispatch::Request#request_id`.
+    Due to implementation, `config.log_tags = [:request_id]` also works in substitute
+    for `config.log_tags = [:uuid]`.
+
+    *David Ilizarov*
+
+*   Change filter on /rails/info/routes to use an actual path regexp from rails
+    and not approximate javascript version. Oniguruma supports much more
+    extensive list of features than javascript regexp engine.
+
+    Fixes #18402.
+
+    *Ravil Bayramgalin*
+
+*   Non-string authenticity tokens do not raise NoMethodError when decoding
+    the masked token.
+
+    *Ville Lautanala*
+
+*   Add `http_cache_forever` to Action Controller, so we can cache a response
+    that never gets expired.
+
+    *arthurnn*
+
+*   `ActionController#translate` supports symbols as shortcuts.
+    When a shortcut is given it also performs the lookup without the action
+    name.
+
+    *Max Melentiev*
+
+*   Expand `ActionController::ConditionalGet#fresh_when` and `stale?` to also
+    accept a collection of records as the first argument, so that the
+    following code can be written in a shorter form.
+
+        # Before
+        def index
+          @articles = Article.all
+          fresh_when(etag: @articles, last_modified: @articles.maximum(:updated_at))
+        end
+
+        # After
+        def index
+          @articles = Article.all
+          fresh_when(@articles)
+        end
+
+    *claudiob*
+
+*   Explicitly ignored wildcard verbs when searching for HEAD routes before fallback
+
+    Fixes an issue where a mounted rack app at root would intercept the HEAD
+    request causing an incorrect behavior during the fall back to GET requests.
+
+    Example:
+
+        draw do
+            get '/home' => 'test#index'
+            mount rack_app, at: '/'
+        end
+        head '/home'
+        assert_response :success
+
+    In this case, a HEAD request runs through the routes the first time and fails
+    to match anything. Then, it runs through the list with the fallback and matches
+    `get '/home'`. The original behavior would match the rack app in the first pass.
+
+    *Terence Sun*
+
+*   Migrating xhr methods to keyword arguments syntax
+    in `ActionController::TestCase` and `ActionDispatch::Integration`
+
+    Old syntax:
+
+        xhr :get, :create, params: { id: 1 }
+
+    New syntax example:
+
+        get :create, params: { id: 1 }, xhr: true
+
+    *Kir Shatrov*
+
+*   Migrating to keyword arguments syntax in `ActionController::TestCase` and
+    `ActionDispatch::Integration` HTTP request methods.
+
+    Example:
+
+        post :create, params: { y: x }, session: { a: 'b' }
+        get :view, params: { id: 1 }
+        get :view, params: { id: 1 }, format: :json
+
+    *Kir Shatrov*
+
+*   Preserve default url options when generating URLs.
+
+    Fixes an issue that would cause `default_url_options` to be lost when
+    generating URLs with fewer positional arguments than parameters in the
+    route definition.
+
+    *Tekin Suleyman*
+
+*   Deprecate `*_via_redirect` integration test methods.
+
+    Use `follow_redirect!` manually after the request call for the same behavior.
+
+    *Aditya Kapoor*
+
+*   Add `ActionController::Renderer` to render arbitrary templates
+    outside controller actions.
+
+    Its functionality is accessible through class methods `render` and
+    `renderer` of `ActionController::Base`.
+
+    *Ravil Bayramgalin*
+
+*   Support `:assigns` option when rendering with controllers/mailers.
+
+    *Ravil Bayramgalin*
+
 *   Default headers, removed in controller actions, are no longer reapplied on
     the test response.
 
     *Jonas Baumann*
 
-*   Deprecate all *_filter callbacks in favor of *_action callbacks.
+*   Deprecate all `*_filter` callbacks in favor of `*_action` callbacks.
 
     *Rafael Mendonça França*
 
-*   Allow you to pass `prepend: false` to protect_from_forgery to have the
+*   Allow you to pass `prepend: false` to `protect_from_forgery` to have the
     verification callback appended instead of prepended to the chain.
     This allows you to let the verification step depend on prior callbacks.
+
     Example:
 
         class ApplicationController < ActionController::Base
@@ -77,7 +491,7 @@
 
 *   Ensure `append_info_to_payload` is called even if an exception is raised.
 
-    Fixes an issue where when an exception is raised in the request the additonal
+    Fixes an issue where when an exception is raised in the request the additional
     payload data is not available.
 
     See:
@@ -106,9 +520,9 @@
 
     *Travis Grathwell*
 
-*   Stop converting empty arrays in `params` to `nil`
+*   Stop converting empty arrays in `params` to `nil`.
 
-    This behaviour was introduced in response to CVE-2012-2660, CVE-2012-2694
+    This behavior was introduced in response to CVE-2012-2660, CVE-2012-2694
     and CVE-2013-0155
 
     ActiveRecord now issues a safe query when passing an empty array into
diff --git a/actionpack/README.rdoc b/actionpack/README.rdoc
index 02a24a7412..44c980b070 100644
--- a/actionpack/README.rdoc
+++ b/actionpack/README.rdoc
@@ -28,7 +28,7 @@ can be used outside of Rails.
 
 The latest version of Action Pack can be installed with RubyGems:
 
-  % [sudo] gem install actionpack
+  % gem install actionpack
 
 Source code can be downloaded as part of the Rails project on GitHub
 
diff --git a/actionpack/Rakefile b/actionpack/Rakefile
index 4b60b77759..601263bfac 100644
--- a/actionpack/Rakefile
+++ b/actionpack/Rakefile
@@ -1,5 +1,4 @@
 require 'rake/testtask'
-require 'rubygems/package_task'
 
 test_files = Dir.glob('test/**/*_test.rb')
 
@@ -9,10 +8,7 @@ task :default => :test
 # Run the unit tests
 Rake::TestTask.new do |t|
   t.libs << 'test'
-
-  # make sure we include the tests in alphabetical order as on some systems
-  # this will not happen automatically and the tests (as a whole) will error
-  t.test_files = test_files.sort
+  t.test_files = test_files
 
   t.warning = true
   t.verbose = true
@@ -27,19 +23,6 @@ namespace :test do
   end
 end
 
-spec = eval(File.read('actionpack.gemspec'))
-
-Gem::PackageTask.new(spec) do |p|
-  p.gem_spec = spec
-end
-
-desc "Release to rubygems"
-task :release => :package do
-  require 'rake/gemcutter'
-  Rake::Gemcutter::Tasks.new(spec).define
-  Rake::Task['gem:push'].invoke
-end
-
 task :lines do
   load File.expand_path('..', File.dirname(__FILE__)) + '/tools/line_statistics'
   files = FileList["lib/**/*.rb"]
diff --git a/actionpack/actionpack.gemspec b/actionpack/actionpack.gemspec
index d9b23ad4a9..28d8bc3091 100644
--- a/actionpack/actionpack.gemspec
+++ b/actionpack/actionpack.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'Web-flow and rendering framework putting the VC in MVC (part of Rails).'
   s.description = 'Web apps on Rails. Simple, battle-tested conventions for building and testing MVC web applications. Works with any Rack-compatible server.'
 
-  s.required_ruby_version = '>= 2.2.0'
+  s.required_ruby_version = '>= 2.2.2'
 
   s.license = 'MIT'
 
@@ -21,9 +21,9 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'activesupport', version
 
-  s.add_dependency 'rack',      '~> 1.6'
-  s.add_dependency 'rack-test', '~> 0.6.2'
-  s.add_dependency 'rails-html-sanitizer', '~> 1.0', '>= 1.0.1'
+  s.add_dependency 'rack',      '~> 2.x'
+  s.add_dependency 'rack-test', '~> 0.6.3'
+  s.add_dependency 'rails-html-sanitizer', '~> 1.0', '>= 1.0.2'
   s.add_dependency 'rails-dom-testing', '~> 1.0', '>= 1.0.5'
   s.add_dependency 'actionview', version
 
diff --git a/actionpack/bin/test b/actionpack/bin/test
new file mode 100755
index 0000000000..404cabba51
--- /dev/null
+++ b/actionpack/bin/test
@@ -0,0 +1,4 @@
+#!/usr/bin/env ruby
+COMPONENT_ROOT = File.expand_path("../../", __FILE__)
+require File.expand_path("../tools/test", COMPONENT_ROOT)
+exit Minitest.run(ARGV)
diff --git a/actionpack/lib/abstract_controller.rb b/actionpack/lib/abstract_controller.rb
index fe9802e395..56c4033387 100644
--- a/actionpack/lib/abstract_controller.rb
+++ b/actionpack/lib/abstract_controller.rb
@@ -1,7 +1,5 @@
 require 'action_pack'
 require 'active_support/rails'
-require 'active_support/core_ext/module/attr_internal'
-require 'active_support/core_ext/module/anonymous'
 require 'active_support/i18n'
 
 module AbstractController
diff --git a/actionpack/lib/abstract_controller/base.rb b/actionpack/lib/abstract_controller/base.rb
index c95b9a4097..4501202b8c 100644
--- a/actionpack/lib/abstract_controller/base.rb
+++ b/actionpack/lib/abstract_controller/base.rb
@@ -1,8 +1,8 @@
 require 'erubis'
-require 'set'
 require 'active_support/configurable'
 require 'active_support/descendants_tracker'
 require 'active_support/core_ext/module/anonymous'
+require 'active_support/core_ext/module/attr_internal'
 
 module AbstractController
   class Error < StandardError #:nodoc:
@@ -88,7 +88,7 @@ module AbstractController
       # Returns the full controller name, underscored, without the ending Controller.
       #
       #   class MyApp::MyPostsController < AbstractController::Base
-      #     end
+      #
       #   end
       #
       #   MyApp::MyPostsController.controller_path # => "my_app/my_posts"
@@ -96,7 +96,7 @@ module AbstractController
       # ==== Returns
       # * <tt>String</tt>
       def controller_path
-        @controller_path ||= name.sub(/Controller$/, '').underscore unless anonymous?
+        @controller_path ||= name.sub(/Controller$/, ''.freeze).underscore unless anonymous?
       end
 
       # Refresh the cached action_methods when a new action_method is added.
@@ -148,9 +148,6 @@ module AbstractController
     #
     # ==== Parameters
     # * <tt>action_name</tt> - The name of an action to be tested
-    #
-    # ==== Returns
-    # * <tt>TrueClass</tt>, <tt>FalseClass</tt>
     def available_action?(action_name)
       _find_action_name(action_name).present?
     end
@@ -171,9 +168,6 @@ module AbstractController
       # ==== Parameters
       # * <tt>name</tt> - The name of an action to be tested
       #
-      # ==== Returns
-      # * <tt>TrueClass</tt>, <tt>FalseClass</tt>
-      #
       # :api: private
       def action_method?(name)
         self.class.action_methods.include?(name)
diff --git a/actionpack/lib/abstract_controller/callbacks.rb b/actionpack/lib/abstract_controller/callbacks.rb
index db999c2765..287550db42 100644
--- a/actionpack/lib/abstract_controller/callbacks.rb
+++ b/actionpack/lib/abstract_controller/callbacks.rb
@@ -1,5 +1,3 @@
-require 'active_support/deprecation'
-
 module AbstractController
   module Callbacks
     extend ActiveSupport::Concern
@@ -63,13 +61,14 @@ module AbstractController
       #   impossible to skip a callback defined using an anonymous proc
       #   using #skip_action_callback
       def skip_action_callback(*names)
-        skip_before_action(*names)
-        skip_after_action(*names)
-        skip_around_action(*names)
+        ActiveSupport::Deprecation.warn('`skip_action_callback` is deprecated and will be removed in Rails 5.1. Please use skip_before_action, skip_after_action or skip_around_action instead.')
+        skip_before_action(*names, raise: false)
+        skip_after_action(*names, raise: false)
+        skip_around_action(*names, raise: false)
       end
 
       def skip_filter(*names)
-        ActiveSupport::Deprecation.warn("#{callback}_filter is deprecated and will removed in Rails 5.1. Use #{callback}_action instead.")
+        ActiveSupport::Deprecation.warn("`skip_filter` is deprecated and will be removed in Rails 5.1. Use skip_before_action, skip_after_action or skip_around_action instead.")
         skip_action_callback(*names)
       end
 
@@ -188,7 +187,7 @@ module AbstractController
         end
 
         define_method "#{callback}_filter" do |*names, &blk|
-          ActiveSupport::Deprecation.warn("#{callback}_filter is deprecated and will removed in Rails 5.1. Use #{callback}_action instead.")
+          ActiveSupport::Deprecation.warn("#{callback}_filter is deprecated and will be removed in Rails 5.1. Use #{callback}_action instead.")
           send("#{callback}_action", *names, &blk)
         end
 
@@ -199,7 +198,7 @@ module AbstractController
         end
 
         define_method "prepend_#{callback}_filter" do |*names, &blk|
-          ActiveSupport::Deprecation.warn("prepend_#{callback}_filter is deprecated and will removed in Rails 5.1. Use prepend_#{callback}_action instead.")
+          ActiveSupport::Deprecation.warn("prepend_#{callback}_filter is deprecated and will be removed in Rails 5.1. Use prepend_#{callback}_action instead.")
           send("prepend_#{callback}_action", *names, &blk)
         end
 
@@ -212,7 +211,7 @@ module AbstractController
         end
 
         define_method "skip_#{callback}_filter" do |*names, &blk|
-          ActiveSupport::Deprecation.warn("skip_#{callback}_filter is deprecated and will removed in Rails 5.1. Use skip_#{callback}_action instead.")
+          ActiveSupport::Deprecation.warn("skip_#{callback}_filter is deprecated and will be removed in Rails 5.1. Use skip_#{callback}_action instead.")
           send("skip_#{callback}_action", *names, &blk)
         end
 
@@ -220,7 +219,7 @@ module AbstractController
         alias_method :"append_#{callback}_action", :"#{callback}_action"
 
         define_method "append_#{callback}_filter" do |*names, &blk|
-          ActiveSupport::Deprecation.warn("append_#{callback}_filter is deprecated and will removed in Rails 5.1. Use append_#{callback}_action instead.")
+          ActiveSupport::Deprecation.warn("append_#{callback}_filter is deprecated and will be removed in Rails 5.1. Use append_#{callback}_action instead.")
           send("append_#{callback}_action", *names, &blk)
         end
       end
diff --git a/actionpack/lib/abstract_controller/collector.rb b/actionpack/lib/abstract_controller/collector.rb
index ddd56b354a..55654be224 100644
--- a/actionpack/lib/abstract_controller/collector.rb
+++ b/actionpack/lib/abstract_controller/collector.rb
@@ -4,11 +4,10 @@ module AbstractController
   module Collector
     def self.generate_method_for_mime(mime)
       sym = mime.is_a?(Symbol) ? mime : mime.to_sym
-      const = sym.upcase
       class_eval <<-RUBY, __FILE__, __LINE__ + 1
-        def #{sym}(*args, &block)                # def html(*args, &block)
-          custom(Mime::#{const}, *args, &block)  #   custom(Mime::HTML, *args, &block)
-        end                                      # end
+        def #{sym}(*args, &block)
+          custom(Mime[:#{sym}], *args, &block)
+        end
       RUBY
     end
 
@@ -23,9 +22,7 @@ module AbstractController
   protected
 
     def method_missing(symbol, &block)
-      const_name = symbol.upcase
-
-      unless Mime.const_defined?(const_name)
+      unless mime_constant = Mime[symbol]
         raise NoMethodError, "To respond to a custom format, register it as a MIME type first: " \
           "http://guides.rubyonrails.org/action_controller_overview.html#restful-downloads. " \
           "If you meant to respond to a variant like :tablet or :phone, not a custom format, " \
@@ -33,8 +30,6 @@ module AbstractController
           "format.html { |html| html.tablet { ... } }"
       end
 
-      mime_constant = Mime.const_get(const_name)
-
       if Mime::SET.include?(mime_constant)
         AbstractController::Collector.generate_method_for_mime(mime_constant)
         send(symbol, &block)
diff --git a/actionpack/lib/abstract_controller/helpers.rb b/actionpack/lib/abstract_controller/helpers.rb
index 109eff10eb..d84c238a62 100644
--- a/actionpack/lib/abstract_controller/helpers.rb
+++ b/actionpack/lib/abstract_controller/helpers.rb
@@ -181,7 +181,7 @@ module AbstractController
       end
 
       def default_helper_module!
-        module_name = name.sub(/Controller$/, '')
+        module_name = name.sub(/Controller$/, ''.freeze)
         module_path = module_name.underscore
         helper module_path
       rescue LoadError => e
diff --git a/actionpack/lib/abstract_controller/railties/routes_helpers.rb b/actionpack/lib/abstract_controller/railties/routes_helpers.rb
index 568c47e43a..14b574e322 100644
--- a/actionpack/lib/abstract_controller/railties/routes_helpers.rb
+++ b/actionpack/lib/abstract_controller/railties/routes_helpers.rb
@@ -6,9 +6,9 @@ module AbstractController
           define_method(:inherited) do |klass|
             super(klass)
             if namespace = klass.parents.detect { |m| m.respond_to?(:railtie_routes_url_helpers) }
-              klass.send(:include, namespace.railtie_routes_url_helpers(include_path_helpers))
+              klass.include(namespace.railtie_routes_url_helpers(include_path_helpers))
             else
-              klass.send(:include, routes.url_helpers(include_path_helpers))
+              klass.include(routes.url_helpers(include_path_helpers))
             end
           end
         end
diff --git a/actionpack/lib/abstract_controller/rendering.rb b/actionpack/lib/abstract_controller/rendering.rb
index 5514213ad8..a73f188623 100644
--- a/actionpack/lib/abstract_controller/rendering.rb
+++ b/actionpack/lib/abstract_controller/rendering.rb
@@ -22,9 +22,13 @@ module AbstractController
     # :api: public
     def render(*args, &block)
       options = _normalize_render(*args, &block)
-      self.response_body = render_to_body(options)
-      _process_format(rendered_format, options) if rendered_format
-      self.response_body
+      rendered_body = render_to_body(options)
+      if options[:html]
+        _set_html_content_type
+      else
+        _set_rendered_content_type rendered_format
+      end
+      self.response_body = rendered_body
     end
 
     # Raw rendering of a template to a string.
@@ -51,14 +55,14 @@ module AbstractController
     # Returns Content-Type of rendered content
     # :api: public
     def rendered_format
-      Mime::TEXT
+      Mime[:text]
     end
 
-    DEFAULT_PROTECTED_INSTANCE_VARIABLES = Set.new %w(
+    DEFAULT_PROTECTED_INSTANCE_VARIABLES = Set.new %i(
       @_action_name @_response_body @_formats @_prefixes @_config
       @_view_context_class @_view_renderer @_lookup_context
       @_routes @_db_runtime
-    ).map(&:to_sym)
+    )
 
     # This method should return a hash with assigns.
     # You can overwrite this configuration per controller.
@@ -99,7 +103,13 @@ module AbstractController
 
     # Process the rendered format.
     # :api: private
-    def _process_format(format, options = {})
+    def _process_format(format)
+    end
+
+    def _set_html_content_type # :nodoc:
+    end
+
+    def _set_rendered_content_type(format) # :nodoc:
     end
 
     # Normalize args and options.
@@ -107,7 +117,7 @@ module AbstractController
     def _normalize_render(*args, &block)
       options = _normalize_args(*args, &block)
       #TODO: remove defined? when we restore AP <=> AV dependency
-      if defined?(request) && request && request.variant.present?
+      if defined?(request) && request.variant.present?
         options[:variant] = request.variant
       end
       _normalize_options(options)
diff --git a/actionpack/lib/abstract_controller/translation.rb b/actionpack/lib/abstract_controller/translation.rb
index 02028d8e05..56b8ce895e 100644
--- a/actionpack/lib/abstract_controller/translation.rb
+++ b/actionpack/lib/abstract_controller/translation.rb
@@ -8,14 +8,15 @@ module AbstractController
     # <tt>I18n.translate("people.index.foo")</tt>. This makes it less repetitive
     # to translate many keys within the same controller / action and gives you a
     # simple framework for scoping them consistently.
-    def translate(*args)
-      key = args.first
-      if key.is_a?(String) && (key[0] == '.')
-        key = "#{ controller_path.tr('/', '.') }.#{ action_name }#{ key }"
-        args[0] = key
+    def translate(key, options = {})
+      if key.to_s.first == '.'
+        path = controller_path.tr('/', '.')
+        defaults = [:"#{path}#{key}"]
+        defaults << options[:default] if options[:default]
+        options[:default] = defaults
+        key = "#{path}.#{action_name}#{key}"
       end
-
-      I18n.translate(*args)
+      I18n.translate(key, options)
     end
     alias :t :translate
 
diff --git a/actionpack/lib/action_controller.rb b/actionpack/lib/action_controller.rb
index e977bbce99..3d3af555c9 100644
--- a/actionpack/lib/action_controller.rb
+++ b/actionpack/lib/action_controller.rb
@@ -7,13 +7,15 @@ require 'action_controller/metal/strong_parameters'
 module ActionController
   extend ActiveSupport::Autoload
 
+  autoload :API
   autoload :Base
   autoload :Caching
   autoload :Metal
   autoload :Middleware
+  autoload :Renderer
+  autoload :FormBuilder
 
   autoload_under "metal" do
-    autoload :Compatibility
     autoload :ConditionalGet
     autoload :Cookies
     autoload :DataStreaming
@@ -23,11 +25,11 @@ module ActionController
     autoload :Head
     autoload :Helpers
     autoload :HttpAuthentication
+    autoload :BasicImplicitRender
     autoload :ImplicitRender
     autoload :Instrumentation
     autoload :MimeResponds
     autoload :ParamsWrapper
-    autoload :RackDelegation
     autoload :Redirecting
     autoload :Renderers
     autoload :Rendering
diff --git a/actionpack/lib/action_controller/api.rb b/actionpack/lib/action_controller/api.rb
new file mode 100644
index 0000000000..1a46d49a49
--- /dev/null
+++ b/actionpack/lib/action_controller/api.rb
@@ -0,0 +1,146 @@
+require 'action_view'
+require 'action_controller'
+require 'action_controller/log_subscriber'
+
+module ActionController
+  # API Controller is a lightweight version of <tt>ActionController::Base</tt>,
+  # created for applications that don't require all functionalities that a complete
+  # \Rails controller provides, allowing you to create controllers with just the
+  # features that you need for API only applications.
+  #
+  # An API Controller is different from a normal controller in the sense that
+  # by default it doesn't include a number of features that are usually required
+  # by browser access only: layouts and templates rendering, cookies, sessions,
+  # flash, assets, and so on. This makes the entire controller stack thinner,
+  # suitable for API applications. It doesn't mean you won't have such
+  # features if you need them: they're all available for you to include in
+  # your application, they're just not part of the default API Controller stack.
+  #
+  # By default, only the ApplicationController in a \Rails application inherits
+  # from <tt>ActionController::API</tt>. All other controllers in turn inherit
+  # from ApplicationController.
+  #
+  # A sample controller could look like this:
+  #
+  #   class PostsController < ApplicationController
+  #     def index
+  #       @posts = Post.all
+  #       render json: @posts
+  #     end
+  #   end
+  #
+  # Request, response and parameters objects all work the exact same way as
+  # <tt>ActionController::Base</tt>.
+  #
+  # == Renders
+  #
+  # The default API Controller stack includes all renderers, which means you
+  # can use <tt>render :json</tt> and brothers freely in your controllers. Keep
+  # in mind that templates are not going to be rendered, so you need to ensure
+  # your controller is calling either <tt>render</tt> or <tt>redirect</tt> in
+  # all actions, otherwise it will return 204 No Content response.
+  #
+  #   def show
+  #     @post = Post.find(params[:id])
+  #     render json: @post
+  #   end
+  #
+  # == Redirects
+  #
+  # Redirects are used to move from one action to another. You can use the
+  # <tt>redirect</tt> method in your controllers in the same way as
+  # <tt>ActionController::Base</tt>. For example:
+  #
+  #   def create
+  #     redirect_to root_url and return if not_authorized?
+  #     # do stuff here
+  #   end
+  #
+  # == Adding new behavior
+  #
+  # In some scenarios you may want to add back some functionality provided by
+  # <tt>ActionController::Base</tt> that is not present by default in
+  # <tt>ActionController::API</tt>, for instance <tt>MimeResponds</tt>. This
+  # module gives you the <tt>respond_to</tt> method. Adding it is quite simple,
+  # you just need to include the module in a specific controller or in
+  # +ApplicationController+ in case you want it available in your entire
+  # application:
+  #
+  #   class ApplicationController < ActionController::API
+  #     include ActionController::MimeResponds
+  #   end
+  #
+  #   class PostsController < ApplicationController
+  #     def index
+  #       @posts = Post.all
+  #
+  #       respond_to do |format|
+  #         format.json { render json: @posts }
+  #         format.xml  { render xml: @posts }
+  #       end
+  #     end
+  #   end
+  #
+  # Quite straightforward. Make sure to check <tt>ActionController::Base</tt>
+  # available modules if you want to include any other functionality that is
+  # not provided by <tt>ActionController::API</tt> out of the box.
+  class API < Metal
+    abstract!
+
+    # Shortcut helper that returns all the ActionController::API modules except
+    # the ones passed as arguments:
+    #
+    #   class MyAPIBaseController < ActionController::Metal
+    #     ActionController::API.without_modules(:ForceSSL, :UrlFor).each do |left|
+    #       include left
+    #     end
+    #   end
+    #
+    # This gives better control over what you want to exclude and makes it easier
+    # to create an API controller class, instead of listing the modules required
+    # manually.
+    def self.without_modules(*modules)
+      modules = modules.map do |m|
+        m.is_a?(Symbol) ? ActionController.const_get(m) : m
+      end
+
+      MODULES - modules
+    end
+
+    MODULES = [
+      AbstractController::Rendering,
+
+      UrlFor,
+      Redirecting,
+      Rendering,
+      Renderers::All,
+      ConditionalGet,
+      BasicImplicitRender,
+      StrongParameters,
+
+      ForceSSL,
+      DataStreaming,
+
+      # Before callbacks should also be executed as early as possible, so
+      # also include them at the bottom.
+      AbstractController::Callbacks,
+
+      # Append rescue at the bottom to wrap as much as possible.
+      Rescue,
+
+      # Add instrumentations hooks at the bottom, to ensure they instrument
+      # all the methods properly.
+      Instrumentation,
+
+      # Params wrapper should come before instrumentation so they are
+      # properly showed in logs
+      ParamsWrapper
+    ]
+
+    MODULES.each do |mod|
+      include mod
+    end
+
+    ActiveSupport.run_load_hooks(:action_controller, self)
+  end
+end
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index e6038396f9..04e5922ce8 100644
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -50,9 +50,9 @@ module ActionController
   #
   # == Parameters
   #
-  # All request parameters, whether they come from a GET or POST request, or from the URL, are available through the params method
-  # which returns a hash. For example, an action that was performed through <tt>/posts?category=All&limit=5</tt> will include
-  # <tt>{ "category" => "All", "limit" => "5" }</tt> in params.
+  # All request parameters, whether they come from a query string in the URL or form data submitted through a POST request are
+  # available through the params method which returns a hash. For example, an action that was performed through
+  # <tt>/posts?category=All&limit=5</tt> will include <tt>{ "category" => "All", "limit" => "5" }</tt> in params.
   #
   # It's also possible to construct multi-dimensional parameter hashes by specifying keys using brackets, such as:
   #
@@ -183,7 +183,7 @@ module ActionController
     # Shortcut helper that returns all the modules included in
     # ActionController::Base except the ones passed as arguments:
     #
-    #   class MetalController
+    #   class MyBaseController < ActionController::Metal
     #     ActionController::Base.without_modules(:ParamsWrapper, :Streaming).each do |left|
     #       include left
     #     end
@@ -213,7 +213,6 @@ module ActionController
       Renderers::All,
       ConditionalGet,
       EtagWithTemplateDigest,
-      RackDelegation,
       Caching,
       MimeResponds,
       ImplicitRender,
@@ -221,6 +220,7 @@ module ActionController
 
       Cookies,
       Flash,
+      FormBuilder,
       RequestForgeryProtection,
       ForceSSL,
       Streaming,
@@ -248,20 +248,17 @@ module ActionController
     MODULES.each do |mod|
       include mod
     end
+    setup_renderer!
 
     # Define some internal variables that should not be propagated to the view.
     PROTECTED_IVARS = AbstractController::Rendering::DEFAULT_PROTECTED_INSTANCE_VARIABLES + [
-      :@_status, :@_headers, :@_params, :@_env, :@_response, :@_request,
+      :@_params, :@_response, :@_request,
       :@_view_runtime, :@_stream, :@_url_options, :@_action_has_layout ]
 
     def _protected_ivars # :nodoc:
       PROTECTED_IVARS
     end
 
-    def self.protected_instance_variables
-      PROTECTED_IVARS
-    end
-
     ActiveSupport.run_load_hooks(:action_controller, self)
   end
 end
diff --git a/actionpack/lib/action_controller/caching.rb b/actionpack/lib/action_controller/caching.rb
index de85e0c1a7..0b8fa2ea09 100644
--- a/actionpack/lib/action_controller/caching.rb
+++ b/actionpack/lib/action_controller/caching.rb
@@ -1,6 +1,5 @@
 require 'fileutils'
 require 'uri'
-require 'set'
 
 module ActionController
   # \Caching is a cheap way of speeding up slow applications by keeping the result of
@@ -8,7 +7,7 @@ module ActionController
   #
   # You can read more about each approach by clicking the modules below.
   #
-  # Note: To turn off all caching, set
+  # Note: To turn off all caching provided by Action Controller, set
   #   config.action_controller.perform_caching = false
   #
   # == \Caching stores
@@ -46,7 +45,6 @@ module ActionController
         end
     end
 
-    include RackDelegation
     include AbstractController::Callbacks
 
     include ConfigMethods
diff --git a/actionpack/lib/action_controller/form_builder.rb b/actionpack/lib/action_controller/form_builder.rb
new file mode 100644
index 0000000000..f2656ca894
--- /dev/null
+++ b/actionpack/lib/action_controller/form_builder.rb
@@ -0,0 +1,48 @@
+module ActionController
+  # Override the default form builder for all views rendered by this
+  # controller and any of its descendants. Accepts a subclass of
+  # +ActionView::Helpers::FormBuilder+.
+  #
+  # For example, given a form builder:
+  #
+  #   class AdminFormBuilder < ActionView::Helpers::FormBuilder
+  #     def special_field(name)
+  #     end
+  #   end
+  #
+  # The controller specifies a form builder as its default:
+  #
+  #   class AdminAreaController < ApplicationController
+  #     default_form_builder AdminFormBuilder
+  #   end
+  #
+  # Then in the view any form using +form_for+ will be an instance of the
+  # specified form builder:
+  #
+  #   <%= form_for(@instance) do |builder| %>
+  #     <%= builder.special_field(:name) %>
+  #   <% end %>
+  module FormBuilder
+    extend ActiveSupport::Concern
+
+    included do
+      class_attribute :_default_form_builder, instance_accessor: false
+    end
+
+    module ClassMethods
+      # Set the form builder to be used as the default for all forms
+      # in the views rendered by this controller and its subclasses.
+      #
+      # ==== Parameters
+      # * <tt>builder</tt> - Default form builder, an instance of +ActionView::Helpers::FormBuilder+
+      def default_form_builder(builder)
+        self._default_form_builder = builder
+      end
+    end
+
+    # Default form builder for the controller
+    def default_form_builder
+      self.class._default_form_builder
+    end
+  end
+end
diff --git a/actionpack/lib/action_controller/log_subscriber.rb b/actionpack/lib/action_controller/log_subscriber.rb
index 87609d8aa7..4c9f14e409 100644
--- a/actionpack/lib/action_controller/log_subscriber.rb
+++ b/actionpack/lib/action_controller/log_subscriber.rb
@@ -25,7 +25,7 @@ module ActionController
           status = ActionDispatch::ExceptionWrapper.status_code_for_exception(exception_class_name)
         end
         message = "Completed #{status} #{Rack::Utils::HTTP_STATUS_CODES[status]} in #{event.duration.round}ms"
-        message << " (#{additions.join(" | ")})" unless additions.blank?
+        message << " (#{additions.join(" | ".freeze)})" unless additions.blank?
         message
       end
     end
diff --git a/actionpack/lib/action_controller/metal.rb b/actionpack/lib/action_controller/metal.rb
index 993f8e150d..8e040bb465 100644
--- a/actionpack/lib/action_controller/metal.rb
+++ b/actionpack/lib/action_controller/metal.rb
@@ -1,5 +1,7 @@
 require 'active_support/core_ext/array/extract_options'
 require 'action_dispatch/middleware/stack'
+require 'action_dispatch/http/request'
+require 'action_dispatch/http/response'
 
 module ActionController
   # Extend ActionDispatch middleware stack to make it aware of options
@@ -11,22 +13,14 @@ module ActionController
   #
   class MiddlewareStack < ActionDispatch::MiddlewareStack #:nodoc:
     class Middleware < ActionDispatch::MiddlewareStack::Middleware #:nodoc:
-      def initialize(klass, *args, &block)
-        options = args.extract_options!
-        @only   = Array(options.delete(:only)).map(&:to_s)
-        @except = Array(options.delete(:except)).map(&:to_s)
-        args << options unless options.empty?
-        super
+      def initialize(klass, args, actions, strategy, block)
+        @actions = actions
+        @strategy = strategy
+        super(klass, args, block)
       end
 
       def valid?(action)
-        if @only.present?
-          @only.include?(action)
-        elsif @except.present?
-          !@except.include?(action)
-        else
-          true
-        end
+        @strategy.call @actions, action
       end
     end
 
@@ -37,6 +31,32 @@ module ActionController
         middleware.valid?(action) ? middleware.build(a) : a
       end
     end
+
+    private
+
+    INCLUDE = ->(list, action) { list.include? action }
+    EXCLUDE = ->(list, action) { !list.include? action }
+    NULL    = ->(list, action) { true }
+
+    def build_middleware(klass, args, block)
+      options = args.extract_options!
+      only   = Array(options.delete(:only)).map(&:to_s)
+      except = Array(options.delete(:except)).map(&:to_s)
+      args << options unless options.empty?
+
+      strategy = NULL
+      list     = nil
+
+      if only.any?
+        strategy = INCLUDE
+        list     = only
+      elsif except.any?
+        strategy = EXCLUDE
+        list     = except
+      end
+
+      Middleware.new(get_class(klass), args, list, strategy, block)
+    end
   end
 
   # <tt>ActionController::Metal</tt> is the simplest possible controller, providing a
@@ -98,11 +118,10 @@ module ActionController
   class Metal < AbstractController::Base
     abstract!
 
-    attr_internal_writer :env
-
     def env
-      @_env ||= {}
+      @_request.env
     end
+    deprecate :env
 
     # Returns the last part of the controller's name, underscored, without the ending
     # <tt>Controller</tt>. For instance, PostsController returns <tt>posts</tt>.
@@ -114,23 +133,23 @@ module ActionController
       @controller_name ||= name.demodulize.sub(/Controller$/, '').underscore
     end
 
+    def self.make_response!(request)
+      ActionDispatch::Response.create.tap do |res|
+        res.request = request
+      end
+    end
+
     # Delegates to the class' <tt>controller_name</tt>
     def controller_name
       self.class.controller_name
     end
 
-    # The details below can be overridden to support a specific
-    # Request and Response object. The default ActionController::Base
-    # implementation includes RackDelegation, which makes a request
-    # and response object available. You might wish to control the
-    # environment and response manually for performance reasons.
-
-    attr_internal :headers, :response, :request
+    attr_internal :response, :request
     delegate :session, :to => "@_request"
+    delegate :headers, :status=, :location=, :content_type=,
+             :status, :location, :content_type, :to => "@_response"
 
     def initialize
-      @_headers = {"Content-Type" => "text/html"}
-      @_status = 200
       @_request = nil
       @_response = nil
       @_routes = nil
@@ -145,60 +164,51 @@ module ActionController
       @_params = val
     end
 
-    # Basic implementations for content_type=, location=, and headers are
-    # provided to reduce the dependency on the RackDelegation module
-    # in Renderer and Redirector.
-
-    def content_type=(type)
-      headers["Content-Type"] = type.to_s
-    end
-
-    def content_type
-      headers["Content-Type"]
-    end
-
-    def location
-      headers["Location"]
-    end
-
-    def location=(url)
-      headers["Location"] = url
-    end
+    alias :response_code :status # :nodoc:
 
     # Basic url_for that can be overridden for more robust functionality
     def url_for(string)
       string
     end
 
-    def status
-      @_status
-    end
-    alias :response_code :status # :nodoc:
-
-    def status=(status)
-      @_status = Rack::Utils.status_code(status)
-    end
-
     def response_body=(body)
       body = [body] unless body.nil? || body.respond_to?(:each)
+      response.reset_body!
+      body.each { |part|
+        next if part.empty?
+        response.write part
+      }
       super
     end
 
     # Tests if render or redirect has already happened.
     def performed?
-      response_body || (response && response.committed?)
+      response_body || response.committed?
     end
 
-    def dispatch(name, request) #:nodoc:
-      @_request = request
-      @_env = request.env
-      @_env['action_controller.instance'] = self
+    def dispatch(name, request, response) #:nodoc:
+      set_request!(request)
+      set_response!(response)
       process(name)
+      request.commit_flash
       to_a
     end
 
+    def set_response!(response) # :nodoc:
+      @_response = response
+    end
+
+    def set_request!(request) #:nodoc:
+      @_request = request
+      @_request.controller_instance = self
+    end
+
     def to_a #:nodoc:
-      response ? response.to_a : [status, headers, response_body]
+      response.to_a
+    end
+
+    def reset_session
+      @_request.reset_session
     end
 
     class_attribute :middleware_stack
@@ -226,15 +236,32 @@ module ActionController
       req = ActionDispatch::Request.new env
       action(req.path_parameters[:action]).call(env)
     end
+    class << self; deprecate :call; end
 
     # Returns a Rack endpoint for the given action name.
-    def self.action(name, klass = ActionDispatch::Request)
+    def self.action(name)
       if middleware_stack.any?
         middleware_stack.build(name) do |env|
-          new.dispatch(name, klass.new(env))
+          req = ActionDispatch::Request.new(env)
+          res = make_response! req
+          new.dispatch(name, req, res)
         end
       else
-        lambda { |env| new.dispatch(name, klass.new(env)) }
+        lambda { |env|
+          req = ActionDispatch::Request.new(env)
+          res = make_response! req
+          new.dispatch(name, req, res)
+        }
+      end
+    end
+
+    # Direct dispatch to the controller.  Instantiates the controller, then
+    # executes the action named +name+.
+    def self.dispatch(name, req, res)
+      if middleware_stack.any?
+        middleware_stack.build(name) { |env| new.dispatch(name, req, res) }.call req.env
+      else
+        new.dispatch(name, req, res)
       end
     end
   end
diff --git a/actionpack/lib/action_controller/metal/basic_implicit_render.rb b/actionpack/lib/action_controller/metal/basic_implicit_render.rb
new file mode 100644
index 0000000000..6c6f8381ff
--- /dev/null
+++ b/actionpack/lib/action_controller/metal/basic_implicit_render.rb
@@ -0,0 +1,11 @@
+module ActionController
+  module BasicImplicitRender
+    def send_action(method, *args)
+      super.tap { default_render unless performed? }
+    end
+
+    def default_render(*args)
+      head :no_content
+    end
+  end
+end
diff --git a/actionpack/lib/action_controller/metal/conditional_get.rb b/actionpack/lib/action_controller/metal/conditional_get.rb
index febbc72861..89d589c486 100644
--- a/actionpack/lib/action_controller/metal/conditional_get.rb
+++ b/actionpack/lib/action_controller/metal/conditional_get.rb
@@ -4,7 +4,6 @@ module ActionController
   module ConditionalGet
     extend ActiveSupport::Concern
 
-    include RackDelegation
     include Head
 
     included do
@@ -15,7 +14,7 @@ module ActionController
     module ClassMethods
       # Allows you to consider additional controller-wide information when generating an ETag.
       # For example, if you serve pages tailored depending on who's logged in at the moment, you
-      # may want to add the current user id to be part of the ETag to prevent authorized displaying
+      # may want to add the current user id to be part of the ETag to prevent unauthorized displaying
       # of cached pages.
       #
       #   class InvoicesController < ApplicationController
@@ -40,7 +39,7 @@ module ActionController
     # * <tt>:etag</tt>.
     # * <tt>:last_modified</tt>.
     # * <tt>:public</tt> By default the Cache-Control header is private, set this to
-    #   +true+ if you want your application to be cachable by other devices (proxy caches).
+    #   +true+ if you want your application to be cacheable by other devices (proxy caches).
     # * <tt>:template</tt> By default, the template digest for the current
     #   controller/action is included in ETags. If the action renders a
     #   different template, you can include its digest instead. If the action
@@ -57,15 +56,25 @@ module ActionController
     # This will render the show template if the request isn't sending a matching ETag or
     # If-Modified-Since header and just a <tt>304 Not Modified</tt> response if there's a match.
     #
-    # You can also just pass a record where +last_modified+ will be set by calling
-    # +updated_at+ and the +etag+ by passing the object itself.
+    # You can also just pass a record. In this case +last_modified+ will be set
+    # by calling +updated_at+ and +etag+ by passing the object itself.
     #
     #   def show
     #     @article = Article.find(params[:id])
     #     fresh_when(@article)
     #   end
     #
-    # When passing a record, you can still set whether the public header:
+    # You can also pass an object that responds to +maximum+, such as a
+    # collection of active records. In this case +last_modified+ will be set by
+    # calling +maximum(:updated_at)+ on the collection (the timestamp of the
+    # most recently updated record) and the +etag+ by passing the object itself.
+    #
+    #   def index
+    #     @articles = Article.all
+    #     fresh_when(@articles)
+    #   end
+    #
+    # When passing a record or a collection, you can still set the public header:
     #
     #   def show
     #     @article = Article.find(params[:id])
@@ -77,18 +86,16 @@ module ActionController
     #
     #   before_action { fresh_when @article, template: 'widgets/show' }
     #
-    def fresh_when(record_or_options, additional_options = {})
-      if record_or_options.is_a? Hash
-        options = record_or_options
-        options.assert_valid_keys(:etag, :last_modified, :public, :template)
-      else
-        record  = record_or_options
-        options = { etag: record, last_modified: record.try(:updated_at) }.merge!(additional_options)
+    def fresh_when(object = nil, etag: object, last_modified: nil, public: false, template: nil)
+      last_modified ||= object.try(:updated_at) || object.try(:maximum, :updated_at)
+
+      if etag || template
+        response.etag = combine_etags(etag: etag, last_modified: last_modified,
+          public: public, template: template)
       end
 
-      response.etag          = combine_etags(options)   if options[:etag] || options[:template]
-      response.last_modified = options[:last_modified]  if options[:last_modified]
-      response.cache_control[:public] = true            if options[:public]
+      response.last_modified = last_modified if last_modified
+      response.cache_control[:public] = true if public
 
       head :not_modified if request.fresh?(response)
     end
@@ -103,7 +110,7 @@ module ActionController
     # * <tt>:etag</tt>.
     # * <tt>:last_modified</tt>.
     # * <tt>:public</tt> By default the Cache-Control header is private, set this to
-    #   +true+ if you want your application to be cachable by other devices (proxy caches).
+    #   +true+ if you want your application to be cacheable by other devices (proxy caches).
     # * <tt>:template</tt> By default, the template digest for the current
     #   controller/action is included in ETags. If the action renders a
     #   different template, you can include its digest instead. If the action
@@ -123,8 +130,8 @@ module ActionController
     #     end
     #   end
     #
-    # You can also just pass a record where +last_modified+ will be set by calling
-    # +updated_at+ and the +etag+ by passing the object itself.
+    # You can also just pass a record. In this case +last_modified+ will be set
+    # by calling +updated_at+ and +etag+ by passing the object itself.
     #
     #   def show
     #     @article = Article.find(params[:id])
@@ -137,7 +144,23 @@ module ActionController
     #     end
     #   end
     #
-    # When passing a record, you can still set whether the public header:
+    # You can also pass an object that responds to +maximum+, such as a
+    # collection of active records. In this case +last_modified+ will be set by
+    # calling +maximum(:updated_at)+ on the collection (the timestamp of the
+    # most recently updated record) and the +etag+ by passing the object itself.
+    #
+    #   def index
+    #     @articles = Article.all
+    #
+    #     if stale?(@articles)
+    #       @statistics = @articles.really_expensive_call
+    #       respond_to do |format|
+    #         # all the supported formats
+    #       end
+    #     end
+    #   end
+    #
+    # When passing a record or a collection, you can still set the public header:
     #
     #   def show
     #     @article = Article.find(params[:id])
@@ -157,8 +180,8 @@ module ActionController
     #     super if stale? @article, template: 'widgets/show'
     #   end
     #
-    def stale?(record_or_options, additional_options = {})
-      fresh_when(record_or_options, additional_options)
+    def stale?(object = nil, etag: object, last_modified: nil, public: nil, template: nil)
+      fresh_when(object, etag: etag, last_modified: last_modified, public: public, template: template)
       !request.fresh?(response)
     end
 
@@ -191,6 +214,24 @@ module ActionController
       response.cache_control.replace(:no_cache => true)
     end
 
+    # Cache or yield the block. The cache is supposed to never expire.
+    #
+    # You can use this method when you have a HTTP response that never changes,
+    # and the browser and proxies should cache it indefinitely.
+    #
+    # * +public+: By default, HTTP responses are private, cached only on the
+    #   user's web browser. To allow proxies to cache the response, set +true+ to
+    #   indicate that they can serve the cached response to all users.
+    #
+    # * +version+: the version passed as a key for the cache.
+    def http_cache_forever(public: false, version: 'v1')
+      expires_in 100.years, public: public
+
+      yield if stale?(etag: "#{version}-#{request.fullpath}",
+                      last_modified: Time.parse('2011-01-01').utc,
+                      public: public)
+    end
+
     private
       def combine_etags(options)
         etags = etaggers.map { |etagger| instance_exec(options, &etagger) }.compact
diff --git a/actionpack/lib/action_controller/metal/cookies.rb b/actionpack/lib/action_controller/metal/cookies.rb
index d787f014cd..f8efb2b076 100644
--- a/actionpack/lib/action_controller/metal/cookies.rb
+++ b/actionpack/lib/action_controller/metal/cookies.rb
@@ -2,8 +2,6 @@ module ActionController #:nodoc:
   module Cookies
     extend ActiveSupport::Concern
 
-    include RackDelegation
-
     included do
       helper_method :cookies
     end
diff --git a/actionpack/lib/action_controller/metal/data_streaming.rb b/actionpack/lib/action_controller/metal/data_streaming.rb
index 1abd8d3a33..957e7a3019 100644
--- a/actionpack/lib/action_controller/metal/data_streaming.rb
+++ b/actionpack/lib/action_controller/metal/data_streaming.rb
@@ -72,27 +72,7 @@ module ActionController #:nodoc:
 
         self.status = options[:status] || 200
         self.content_type = options[:content_type] if options.key?(:content_type)
-        self.response_body = FileBody.new(path)
-      end
-
-      # Avoid having to pass an open file handle as the response body.
-      # Rack::Sendfile will usually intercept the response and uses
-      # the path directly, so there is no reason to open the file.
-      class FileBody #:nodoc:
-        attr_reader :to_path
-
-        def initialize(path)
-          @to_path = path
-        end
-
-        # Stream the file's contents if Rack::Sendfile isn't present.
-        def each
-          File.open(to_path, 'rb') do |file|
-            while chunk = file.read(16384)
-              yield chunk
-            end
-          end
-        end
+        response.send_file path
       end
 
       # Sends the given binary data to the browser. This method is similar to
@@ -126,7 +106,7 @@ module ActionController #:nodoc:
       # See +send_file+ for more information on HTTP Content-* headers and caching.
       def send_data(data, options = {}) #:doc:
         send_file_headers! options
-        render options.slice(:status, :content_type).merge(:text => data)
+        render options.slice(:status, :content_type).merge(body: data)
       end
 
     private
diff --git a/actionpack/lib/action_controller/metal/etag_with_template_digest.rb b/actionpack/lib/action_controller/metal/etag_with_template_digest.rb
index f9303efe6c..669cf55bca 100644
--- a/actionpack/lib/action_controller/metal/etag_with_template_digest.rb
+++ b/actionpack/lib/action_controller/metal/etag_with_template_digest.rb
@@ -25,7 +25,7 @@ module ActionController
       class_attribute :etag_with_template_digest
       self.etag_with_template_digest = true
 
-      ActiveSupport.on_load :action_view, yield: true do |action_view_base|
+      ActiveSupport.on_load :action_view, yield: true do
         etag do |options|
           determine_template_etag(options) if etag_with_template_digest
         end
diff --git a/actionpack/lib/action_controller/metal/exceptions.rb b/actionpack/lib/action_controller/metal/exceptions.rb
index 18e003741d..5260dc0336 100644
--- a/actionpack/lib/action_controller/metal/exceptions.rb
+++ b/actionpack/lib/action_controller/metal/exceptions.rb
@@ -5,12 +5,10 @@ module ActionController
   class BadRequest < ActionControllerError #:nodoc:
     attr_reader :original_exception
 
-    def initialize(type = nil, e = nil)
-      return super() unless type && e
-
-      super("Invalid #{type} parameters: #{e.message}")
+    def initialize(msg = nil, e = nil)
+      super(msg)
       @original_exception = e
-      set_backtrace e.backtrace
+      set_backtrace e.backtrace if e
     end
   end
 
diff --git a/actionpack/lib/action_controller/metal/force_ssl.rb b/actionpack/lib/action_controller/metal/force_ssl.rb
index d920668184..e31d65aac2 100644
--- a/actionpack/lib/action_controller/metal/force_ssl.rb
+++ b/actionpack/lib/action_controller/metal/force_ssl.rb
@@ -55,10 +55,10 @@ module ActionController
       # You can pass any of the following options to affect the before_action callback
       # * <tt>only</tt>       - The callback should be run only for this action
       # * <tt>except</tt>     - The callback should be run for all actions except this action
-      # * <tt>if</tt>         - A symbol naming an instance method or a proc; the callback
-      #                         will be called only when it returns a true value.
-      # * <tt>unless</tt>     - A symbol naming an instance method or a proc; the callback
-      #                         will be called only when it returns a false value.
+      # * <tt>if</tt>         - A symbol naming an instance method or a proc; the
+      #   callback will be called only when it returns a true value.
+      # * <tt>unless</tt>     - A symbol naming an instance method or a proc; the
+      #   callback will be called only when it returns a false value.
       def force_ssl(options = {})
         action_options = options.slice(*ACTION_OPTIONS)
         redirect_options = options.except(*ACTION_OPTIONS)
@@ -71,8 +71,8 @@ module ActionController
     # Redirect the existing request to use the HTTPS protocol.
     #
     # ==== Parameters
-    # * <tt>host_or_options</tt> - Either a host name or any of the url & redirect options
-    #                              available to the <tt>force_ssl</tt> method.
+    # * <tt>host_or_options</tt> - Either a host name or any of the url &
+    #   redirect options available to the <tt>force_ssl</tt> method.
     def force_ssl_redirect(host_or_options = nil)
       unless request.ssl?
         options = {
diff --git a/actionpack/lib/action_controller/metal/head.rb b/actionpack/lib/action_controller/metal/head.rb
index 0d93e2f7aa..b2110bf946 100644
--- a/actionpack/lib/action_controller/metal/head.rb
+++ b/actionpack/lib/action_controller/metal/head.rb
@@ -17,8 +17,18 @@ module ActionController
     #
     # See Rack::Utils::SYMBOL_TO_STATUS_CODE for a full list of valid +status+ symbols.
     def head(status, options = {})
-      options, status = status, nil if status.is_a?(Hash)
-      status ||= options.delete(:status) || :ok
+      if status.is_a?(Hash)
+        msg = status[:status] ? 'The :status option' : 'The implicit :ok status'
+        options, status = status, status.delete(:status)
+
+        ActiveSupport::Deprecation.warn(<<-MSG.squish)
+          #{msg} on `head` has been deprecated and will be removed in Rails 5.1.
+          Please pass the status as a separate parameter before the options, instead.
+        MSG
+      end
+
+      status ||= :ok
+
       location = options.delete(:location)
       content_type = options.delete(:content_type)
 
@@ -33,11 +43,10 @@ module ActionController
 
       if include_content?(self.response_code)
         self.content_type = content_type || (Mime[formats.first] if formats)
-        self.response.charset = false if self.response
-      else
-        headers.delete('Content-Type')
-        headers.delete('Content-Length')
+        self.response.charset = false
       end
+
+      true
     end
 
     private
diff --git a/actionpack/lib/action_controller/metal/helpers.rb b/actionpack/lib/action_controller/metal/helpers.rb
index a9c3e438fb..d3853e2e83 100644
--- a/actionpack/lib/action_controller/metal/helpers.rb
+++ b/actionpack/lib/action_controller/metal/helpers.rb
@@ -7,8 +7,8 @@ module ActionController
   # extract complicated logic or reusable functionality is strongly encouraged. By default, each controller
   # will include all helpers. These helpers are only accessible on the controller through <tt>.helpers</tt>
   #
-  # In previous versions of \Rails the controller will include a helper whose
-  # name matches that of the controller, e.g., <tt>MyController</tt> will automatically
+  # In previous versions of \Rails the controller will include a helper which
+  # matches the name of the controller, e.g., <tt>MyController</tt> will automatically
   # include <tt>MyHelper</tt>. To return old behavior set +config.action_controller.include_all_helpers+ to +false+.
   #
   # Additional helpers can be specified using the +helper+ class method in ActionController::Base or any
@@ -44,7 +44,7 @@ module ActionController
   # the output might look like this:
   #
   #   23 Aug 11:30 | Carolina Railhawks Soccer Match
-  #   N/A | Carolina Railhaws Training Workshop
+  #   N/A | Carolina Railhawks Training Workshop
   #
   module Helpers
     extend ActiveSupport::Concern
@@ -73,7 +73,7 @@ module ActionController
 
       # Provides a proxy to access helpers methods from outside the view.
       def helpers
-        @helper_proxy ||= begin 
+        @helper_proxy ||= begin
           proxy = ActionView::Base.new
           proxy.config = config.inheritable_copy
           proxy.extend(_helpers)
@@ -93,10 +93,14 @@ module ActionController
         super(args)
       end
 
+      # Returns a list of helper names in a given path.
+      #
+      #   ActionController::Base.all_helpers_from_path 'app/helpers'
+      #   # => ["application", "chart", "rubygems"]
       def all_helpers_from_path(path)
         helpers = Array(path).flat_map do |_path|
           extract = /^#{Regexp.quote(_path.to_s)}\/?(.*)_helper.rb$/
-          names = Dir["#{_path}/**/*_helper.rb"].map { |file| file.sub(extract, '\1') }
+          names = Dir["#{_path}/**/*_helper.rb"].map { |file| file.sub(extract, '\1'.freeze) }
           names.sort!
         end
         helpers.uniq!
diff --git a/actionpack/lib/action_controller/metal/http_authentication.rb b/actionpack/lib/action_controller/metal/http_authentication.rb
index a219d35b25..0a36fecd27 100644
--- a/actionpack/lib/action_controller/metal/http_authentication.rb
+++ b/actionpack/lib/action_controller/metal/http_authentication.rb
@@ -34,7 +34,7 @@ module ActionController
     #
     #       def authenticate
     #         case request.format
-    #         when Mime::XML, Mime::ATOM
+    #         when Mime[:xml], Mime[:atom]
     #           if user = authenticate_with_http_basic { |u, p| @account.users.authenticate(u, p) }
     #             @current_user = user
     #           else
@@ -74,16 +74,16 @@ module ActionController
           end
         end
 
-        def authenticate_or_request_with_http_basic(realm = "Application", &login_procedure)
-          authenticate_with_http_basic(&login_procedure) || request_http_basic_authentication(realm)
+        def authenticate_or_request_with_http_basic(realm = "Application", message = nil, &login_procedure)
+          authenticate_with_http_basic(&login_procedure) || request_http_basic_authentication(realm, message)
         end
 
         def authenticate_with_http_basic(&login_procedure)
           HttpAuthentication::Basic.authenticate(request, &login_procedure)
         end
 
-        def request_http_basic_authentication(realm = "Application")
-          HttpAuthentication::Basic.authentication_request(self, realm)
+        def request_http_basic_authentication(realm = "Application", message = nil)
+          HttpAuthentication::Basic.authentication_request(self, realm, message)
         end
       end
 
@@ -94,7 +94,7 @@ module ActionController
       end
 
       def has_basic_credentials?(request)
-        request.authorization.present? && (auth_scheme(request) == 'Basic')
+        request.authorization.present? && (auth_scheme(request).downcase == 'basic')
       end
 
       def user_name_and_password(request)
@@ -106,21 +106,22 @@ module ActionController
       end
 
       def auth_scheme(request)
-        request.authorization.split(' ', 2).first
+        request.authorization.to_s.split(' ', 2).first
       end
 
       def auth_param(request)
-        request.authorization.split(' ', 2).second
+        request.authorization.to_s.split(' ', 2).second
       end
 
       def encode_credentials(user_name, password)
         "Basic #{::Base64.strict_encode64("#{user_name}:#{password}")}"
       end
 
-      def authentication_request(controller, realm)
-        controller.headers["WWW-Authenticate"] = %(Basic realm="#{realm.gsub(/"/, "")}")
+      def authentication_request(controller, realm, message)
+        message ||= "HTTP Basic: Access denied.\n"
+        controller.headers["WWW-Authenticate"] = %(Basic realm="#{realm.tr('"'.freeze, "".freeze)}")
         controller.status = 401
-        controller.response_body = "HTTP Basic: Access denied.\n"
+        controller.response_body = message
       end
     end
 
@@ -170,8 +171,8 @@ module ActionController
       extend self
 
       module ControllerMethods
-        def authenticate_or_request_with_http_digest(realm = "Application", &password_procedure)
-          authenticate_with_http_digest(realm, &password_procedure) || request_http_digest_authentication(realm)
+        def authenticate_or_request_with_http_digest(realm = "Application", message = nil, &password_procedure)
+          authenticate_with_http_digest(realm, &password_procedure) || request_http_digest_authentication(realm, message)
         end
 
         # Authenticate with HTTP Digest, returns true or false
@@ -202,7 +203,7 @@ module ActionController
           password = password_procedure.call(credentials[:username])
           return false unless password
 
-          method = request.env['rack.methodoverride.original_method'] || request.env['REQUEST_METHOD']
+          method = request.get_header('rack.methodoverride.original_method') || request.get_header('REQUEST_METHOD')
           uri    = credentials[:uri]
 
           [true, false].any? do |trailing_question_mark|
@@ -259,8 +260,8 @@ module ActionController
       end
 
       def secret_token(request)
-        key_generator  = request.env["action_dispatch.key_generator"]
-        http_auth_salt = request.env["action_dispatch.http_auth_salt"]
+        key_generator  = request.key_generator
+        http_auth_salt = request.http_auth_salt
         key_generator.generate_key(http_auth_salt)
       end
 
@@ -314,7 +315,7 @@ module ActionController
         nonce(secret_key, t) == value && (t - Time.now.to_i).abs <= seconds_to_timeout
       end
 
-      # Opaque based on random generation - but changing each request?
+      # Opaque based on digest of secret key
       def opaque(secret_key)
         ::Digest::MD5.hexdigest(secret_key)
       end
@@ -360,7 +361,7 @@ module ActionController
     #
     #       def authenticate
     #         case request.format
-    #         when Mime::XML, Mime::ATOM
+    #         when Mime[:xml], Mime[:atom]
     #           if user = authenticate_with_http_token { |t, o| @account.users.authenticate(t, o) }
     #             @current_user = user
     #           else
@@ -396,21 +397,21 @@ module ActionController
     #   RewriteRule ^(.*)$ dispatch.fcgi [E=X-HTTP_AUTHORIZATION:%{HTTP:Authorization},QSA,L]
     module Token
       TOKEN_KEY = 'token='
-      TOKEN_REGEX = /^Token /
+      TOKEN_REGEX = /^(Token|Bearer) /
       AUTHN_PAIR_DELIMITERS = /(?:,|;|\t+)/
       extend self
 
       module ControllerMethods
-        def authenticate_or_request_with_http_token(realm = "Application", &login_procedure)
-          authenticate_with_http_token(&login_procedure) || request_http_token_authentication(realm)
+        def authenticate_or_request_with_http_token(realm = "Application", message = nil, &login_procedure)
+          authenticate_with_http_token(&login_procedure) || request_http_token_authentication(realm, message)
         end
 
         def authenticate_with_http_token(&login_procedure)
           Token.authenticate(self, &login_procedure)
         end
 
-        def request_http_token_authentication(realm = "Application")
-          Token.authentication_request(self, realm)
+        def request_http_token_authentication(realm = "Application", message = nil)
+          Token.authentication_request(self, realm, message)
         end
       end
 
@@ -435,15 +436,17 @@ module ActionController
         end
       end
 
-      # Parses the token and options out of the token authorization header. If
-      # the header looks like this:
+      # Parses the token and options out of the token authorization header.
+      # The value for the Authorization header is expected to have the prefix
+      # <tt>"Token"</tt> or <tt>"Bearer"</tt>. If the header looks like this:
       #   Authorization: Token token="abc", nonce="def"
-      # Then the returned token is "abc", and the options is {nonce: "def"}
+      # Then the returned token is <tt>"abc"</tt>, and the options are
+      # <tt>{nonce: "def"}</tt>
       #
       # request - ActionDispatch::Request instance with the current headers.
       #
-      # Returns an Array of [String, Hash] if a token is present.
-      # Returns nil if no token is found.
+      # Returns an +Array+ of <tt>[String, Hash]</tt> if a token is present.
+      # Returns +nil+ if no token is found.
       def token_and_options(request)
         authorization_request = request.authorization.to_s
         if authorization_request[TOKEN_REGEX]
@@ -492,15 +495,16 @@ module ActionController
         "Token #{values * ", "}"
       end
 
-      # Sets a WWW-Authenticate to let the client know a token is desired.
+      # Sets a WWW-Authenticate header to let the client know a token is desired.
       #
       # controller - ActionController::Base instance for the outgoing response.
       # realm      - String realm to use in the header.
       #
       # Returns nothing.
-      def authentication_request(controller, realm)
-        controller.headers["WWW-Authenticate"] = %(Token realm="#{realm.gsub(/"/, "")}")
-        controller.__send__ :render, :text => "HTTP Token: Access denied.\n", :status => :unauthorized
+      def authentication_request(controller, realm, message = nil)
+        message ||= "HTTP Token: Access denied.\n"
+        controller.headers["WWW-Authenticate"] = %(Token realm="#{realm.tr('"'.freeze, "".freeze)}")
+        controller.__send__ :render, plain: message, status: :unauthorized
       end
     end
   end
diff --git a/actionpack/lib/action_controller/metal/implicit_render.rb b/actionpack/lib/action_controller/metal/implicit_render.rb
index ae04b53825..17fcc2fa02 100644
--- a/actionpack/lib/action_controller/metal/implicit_render.rb
+++ b/actionpack/lib/action_controller/metal/implicit_render.rb
@@ -1,13 +1,30 @@
 module ActionController
   module ImplicitRender
-    def send_action(method, *args)
-      ret = super
-      default_render unless performed?
-      ret
-    end
 
+    include BasicImplicitRender
+
+    # Renders the template corresponding to the controller action, if it exists.
+    # The action name, format, and variant are all taken into account.
+    # For example, the "new" action with an HTML format and variant "phone" 
+    # would try to render the <tt>new.html+phone.erb</tt> template.
+    #
+    # If no template is found <tt>ActionController::BasicImplicitRender</tt>'s implementation is called, unless
+    # a block is passed. In that case, it will override the super implementation.
+    #
+    #   default_render do
+    #     head 404 # No template was found
+    #   end
     def default_render(*args)
-      render(*args)
+      if template_exists?(action_name.to_s, _prefixes, variants: request.variant)
+        render(*args)
+      else
+        if block_given?
+          yield(*args)
+        else
+          logger.info "No template found for #{self.class.name}\##{action_name}, rendering head :no_content" if logger
+          super
+        end
+      end
     end
 
     def method_for_action(action_name)
diff --git a/actionpack/lib/action_controller/metal/instrumentation.rb b/actionpack/lib/action_controller/metal/instrumentation.rb
index a3e1a71b0a..3dbf34eb2a 100644
--- a/actionpack/lib/action_controller/metal/instrumentation.rb
+++ b/actionpack/lib/action_controller/metal/instrumentation.rb
@@ -11,7 +11,6 @@ module ActionController
     extend ActiveSupport::Concern
 
     include AbstractController::Logger
-    include ActionController::RackDelegation
 
     attr_internal :view_runtime
 
diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
index 7590fb6843..7db8d13e24 100644
--- a/actionpack/lib/action_controller/metal/live.rb
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -33,6 +33,20 @@ module ActionController
   # the main thread. Make sure your actions are thread safe, and this shouldn't
   # be a problem (don't share state across threads, etc).
   module Live
+    extend ActiveSupport::Concern
+
+    module ClassMethods
+      def make_response!(request)
+        if request.env["HTTP_VERSION"] == "HTTP/1.0"
+          super
+        else
+          Live::Response.new.tap do |res|
+            res.request = request
+          end
+        end
+      end
+    end
+
     # This class provides the ability to write an SSE (Server Sent Event)
     # to an IO stream. The class is initialized with a stream and can be used
     # to either write a JSON string or an object which can be converted to JSON.
@@ -102,7 +116,7 @@ module ActionController
             end
           end
 
-          message = json.gsub(/\n/, "\ndata: ")
+          message = json.gsub("\n".freeze, "\ndata: ".freeze)
           @stream.write "data: #{message}\n\n"
         end
     end
@@ -131,8 +145,8 @@ module ActionController
 
       def write(string)
         unless @response.committed?
-          @response.headers["Cache-Control"] = "no-cache"
-          @response.headers.delete "Content-Length"
+          @response.set_header "Cache-Control", "no-cache"
+          @response.delete_header "Content-Length"
         end
 
         super
@@ -199,29 +213,6 @@ module ActionController
     end
 
     class Response < ActionDispatch::Response #:nodoc: all
-      class Header < DelegateClass(Hash) # :nodoc:
-        def initialize(response, header)
-          @response = response
-          super(header)
-        end
-
-        def []=(k,v)
-          if @response.committed?
-            raise ActionDispatch::IllegalStateError, 'header already sent'
-          end
-
-          super
-        end
-
-        def merge(other)
-          self.class.new @response, __getobj__.merge(other)
-        end
-
-        def to_hash
-          __getobj__.dup
-        end
-      end
-
       private
 
       def before_committed
@@ -242,14 +233,6 @@ module ActionController
         body.each { |part| buf.write part }
         buf
       end
-
-      def merge_default_headers(original, default)
-        Header.new self, super
-      end
-
-      def handle_conditional_get!
-        super unless committed?
-      end
     end
 
     def process(name)
@@ -311,12 +294,7 @@ module ActionController
     end
 
     def set_response!(request)
-      if request.env["HTTP_VERSION"] == "HTTP/1.0"
-        super
-      else
-        @_response         = Live::Response.new
-        @_response.request = request
-      end
+      @_response = self.class.make_response! request
     end
   end
 end
diff --git a/actionpack/lib/action_controller/metal/mime_responds.rb b/actionpack/lib/action_controller/metal/mime_responds.rb
index 7dae171215..6e346fadfe 100644
--- a/actionpack/lib/action_controller/metal/mime_responds.rb
+++ b/actionpack/lib/action_controller/metal/mime_responds.rb
@@ -91,11 +91,11 @@ module ActionController #:nodoc:
     # and accept Rails' defaults, life will be much easier.
     #
     # If you need to use a MIME type which isn't supported by default, you can register your own handlers in
-    # config/initializers/mime_types.rb as follows.
+    # +config/initializers/mime_types.rb+ as follows.
     #
     #   Mime::Type.register "image/jpg", :jpg
     #
-    # Respond to also allows you to specify a common block for different formats by using any:
+    # Respond to also allows you to specify a common block for different formats by using +any+:
     #
     #   def index
     #     @people = Person.all
@@ -151,21 +151,21 @@ module ActionController #:nodoc:
     #     format.html.none  { render "trash" }
     #   end
     #
-    # Variants also support common `any`/`all` block that formats have.
+    # Variants also support common +any+/+all+ block that formats have.
     #
     # It works for both inline:
     #
     #   respond_to do |format|
-    #     format.html.any   { render text: "any"   }
-    #     format.html.phone { render text: "phone" }
+    #     format.html.any   { render html: "any"   }
+    #     format.html.phone { render html: "phone" }
     #   end
     #
     # and block syntax:
     #
     #   respond_to do |format|
     #     format.html do |variant|
-    #       variant.any(:tablet, :phablet){ render text: "any" }
-    #       variant.phone { render text: "phone" }
+    #       variant.any(:tablet, :phablet){ render html: "any" }
+    #       variant.phone { render html: "phone" }
     #     end
     #   end
     #
@@ -174,7 +174,7 @@ module ActionController #:nodoc:
     #   request.variant = [:tablet, :phone]
     #
     # which will work similarly to formats and MIME types negotiation. If there will be no
-    # :tablet variant declared, :phone variant will be picked:
+    # +:tablet+ variant declared, +:phone+ variant will be picked:
     #
     #   respond_to do |format|
     #     format.html.none
@@ -191,6 +191,7 @@ module ActionController #:nodoc:
 
       if format = collector.negotiate_format(request)
         _process_format(format)
+        _set_rendered_content_type format
         response = collector.response
         response ? response.call : render({})
       else
@@ -228,7 +229,7 @@ module ActionController #:nodoc:
         @responses = {}
         @variant = variant
 
-        mimes.each { |mime| @responses["Mime::#{mime.upcase}".constantize] = nil }
+        mimes.each { |mime| @responses[Mime[mime]] = nil }
       end
 
       def any(*args, &block)
@@ -288,16 +289,17 @@ module ActionController #:nodoc:
         end
 
         def variant
-          if @variant.nil?
+          if @variant.empty?
             @variants[:none] || @variants[:any]
-          elsif (@variants.keys & @variant).any?
-            @variant.each do |v|
-              return @variants[v] if @variants.key?(v)
-            end
           else
-            @variants[:any]
+            @variants[variant_key]
           end
         end
+
+        private
+          def variant_key
+            @variant.find { |variant| @variants.key?(variant) } || :any
+          end
       end
     end
   end
diff --git a/actionpack/lib/action_controller/metal/params_wrapper.rb b/actionpack/lib/action_controller/metal/params_wrapper.rb
index a7e734db42..c38fc40b81 100644
--- a/actionpack/lib/action_controller/metal/params_wrapper.rb
+++ b/actionpack/lib/action_controller/metal/params_wrapper.rb
@@ -4,18 +4,17 @@ require 'active_support/core_ext/module/anonymous'
 require 'action_dispatch/http/mime_type'
 
 module ActionController
-  # Wraps the parameters hash into a nested hash. This will allow clients to submit
-  # POST requests without having to specify any root elements.
+  # Wraps the parameters hash into a nested hash. This will allow clients to
+  # submit requests without having to specify any root elements.
   #
   # This functionality is enabled in +config/initializers/wrap_parameters.rb+
-  # and can be customized. If you are upgrading to \Rails 3.1, this file will
-  # need to be created for the functionality to be enabled.
+  # and can be customized.
   #
   # You could also turn it on per controller by setting the format array to
   # a non-empty array:
   #
   #     class UsersController < ApplicationController
-  #       wrap_parameters format: [:json, :xml]
+  #       wrap_parameters format: [:json, :xml, :url_encoded_form, :multipart_form]
   #     end
   #
   # If you enable +ParamsWrapper+ for +:json+ format, instead of having to
@@ -41,7 +40,7 @@ module ActionController
   #       wrap_parameters :person, include: [:username, :password]
   #     end
   #
-  # On ActiveRecord models with no +:include+ or +:exclude+ option set,
+  # On Active Record models with no +:include+ or +:exclude+ option set,
   # it will only wrap the parameters returned by the class method
   # <tt>attribute_names</tt>.
   #
@@ -131,7 +130,7 @@ module ActionController
       private
       # Determine the wrapper model from the controller's name. By convention,
       # this could be done by trying to find the defined model that has the
-      # same singularize name as the controller. For example, +UsersController+
+      # same singular name as the controller. For example, +UsersController+
       # will try to find if the +User+ model exists.
       #
       # This method also does namespace lookup. Foo::Bar::UsersController will
@@ -251,7 +250,7 @@ module ActionController
 
     private
 
-      # Returns the wrapper key which will be used to stored wrapped parameters.
+      # Returns the wrapper key which will be used to store wrapped parameters.
       def _wrapper_key
         _wrapper_options.name
       end
@@ -277,7 +276,9 @@ module ActionController
 
       # Checks if we should perform parameters wrapping.
       def _wrapper_enabled?
-        ref = request.content_mime_type.try(:ref)
+        return false unless request.has_content_type?
+
+        ref = request.content_mime_type.ref
         _wrapper_formats.include?(ref) && _wrapper_key && !request.request_parameters[_wrapper_key]
       end
   end
diff --git a/actionpack/lib/action_controller/metal/rack_delegation.rb b/actionpack/lib/action_controller/metal/rack_delegation.rb
deleted file mode 100644
index 545d4a7e6e..0000000000
--- a/actionpack/lib/action_controller/metal/rack_delegation.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require 'action_dispatch/http/request'
-require 'action_dispatch/http/response'
-
-module ActionController
-  module RackDelegation
-    extend ActiveSupport::Concern
-
-    delegate :headers, :status=, :location=, :content_type=,
-             :status, :location, :content_type, :response_code, :to => "@_response"
-
-    def dispatch(action, request)
-      set_response!(request)
-      super(action, request)
-    end
-
-    def response_body=(body)
-      response.body = body if response
-      super
-    end
-
-    def reset_session
-      @_request.reset_session
-    end
-
-    private
-
-    def set_response!(request)
-      @_response         = ActionDispatch::Response.new
-      @_response.request = request
-    end
-  end
-end
diff --git a/actionpack/lib/action_controller/metal/redirecting.rb b/actionpack/lib/action_controller/metal/redirecting.rb
index acaa8227c9..0febc905f1 100644
--- a/actionpack/lib/action_controller/metal/redirecting.rb
+++ b/actionpack/lib/action_controller/metal/redirecting.rb
@@ -11,7 +11,6 @@ module ActionController
     extend ActiveSupport::Concern
 
     include AbstractController::Logger
-    include ActionController::RackDelegation
     include ActionController::UrlFor
 
     # Redirects the browser to the target specified in +options+. This parameter can be any one of:
diff --git a/actionpack/lib/action_controller/metal/renderers.rb b/actionpack/lib/action_controller/metal/renderers.rb
index 45d3962494..22e0bb5955 100644
--- a/actionpack/lib/action_controller/metal/renderers.rb
+++ b/actionpack/lib/action_controller/metal/renderers.rb
@@ -68,11 +68,11 @@ module ActionController
     #   ActionController::Renderers.add :csv do |obj, options|
     #     filename = options[:filename] || 'data'
     #     str = obj.respond_to?(:to_csv) ? obj.to_csv : obj.to_s
-    #     send_data str, type: Mime::CSV,
+    #     send_data str, type: Mime[:csv],
     #       disposition: "attachment; filename=#{filename}.csv"
     #   end
     #
-    # Note that we used Mime::CSV for the csv mime type as it comes with Rails.
+    # Note that we used Mime[:csv] for the csv mime type as it comes with Rails.
     # For a custom renderer, you'll need to register a mime type with
     # <tt>Mime::Type.register</tt>.
     #
@@ -94,7 +94,7 @@ module ActionController
 
     # This method is the opposite of add method.
     #
-    # Usage:
+    # To remove a csv renderer:
     #
     #   ActionController::Renderers.remove(:csv)
     def self.remove(key)
@@ -116,24 +116,24 @@ module ActionController
       json = json.to_json(options) unless json.kind_of?(String)
 
       if options[:callback].present?
-        if content_type.nil? || content_type == Mime::JSON
-          self.content_type = Mime::JS
+        if content_type.nil? || content_type == Mime[:json]
+          self.content_type = Mime[:js]
         end
 
         "/**/#{options[:callback]}(#{json})"
       else
-        self.content_type ||= Mime::JSON
+        self.content_type ||= Mime[:json]
         json
       end
     end
 
     add :js do |js, options|
-      self.content_type ||= Mime::JS
+      self.content_type ||= Mime[:js]
       js.respond_to?(:to_js) ? js.to_js(options) : js
     end
 
     add :xml do |xml, options|
-      self.content_type ||= Mime::XML
+      self.content_type ||= Mime[:xml]
       xml.respond_to?(:to_xml) ? xml.to_xml(options) : xml
     end
   end
diff --git a/actionpack/lib/action_controller/metal/rendering.rb b/actionpack/lib/action_controller/metal/rendering.rb
index 7bbff0450a..cce6fe7787 100644
--- a/actionpack/lib/action_controller/metal/rendering.rb
+++ b/actionpack/lib/action_controller/metal/rendering.rb
@@ -1,9 +1,29 @@
+require 'active_support/core_ext/string/filters'
+
 module ActionController
   module Rendering
     extend ActiveSupport::Concern
 
     RENDER_FORMATS_IN_PRIORITY = [:body, :text, :plain, :html]
 
+    module ClassMethods
+      # Documentation at ActionController::Renderer#render
+      delegate :render, to: :renderer
+
+      # Returns a renderer instance (inherited from ActionController::Renderer)
+      # for the controller.
+      attr_reader :renderer
+
+      def setup_renderer! # :nodoc:
+        @renderer = Renderer.for(self)
+      end
+
+      def inherited(klass)
+        klass.setup_renderer!
+        super
+      end
+    end
+
     # Before processing, set the request formats in current controller formats.
     def process_action(*) #:nodoc:
       self.formats = request.formats.map(&:ref).compact
@@ -42,13 +62,13 @@ module ActionController
       nil
     end
 
-    def _process_format(format, options = {})
-      super
+    def _set_html_content_type
+      self.content_type = Mime[:html].to_s
+    end
 
-      if options[:plain]
-        self.content_type = Mime::TEXT
-      else
-        self.content_type ||= format.to_s
+    def _set_rendered_content_type(format)
+      unless response.content_type
+        self.content_type = format.to_s
       end
     end
 
@@ -63,11 +83,23 @@ module ActionController
     def _normalize_options(options) #:nodoc:
       _normalize_text(options)
 
+      if options[:text]
+        ActiveSupport::Deprecation.warn <<-WARNING.squish
+          `render :text` is deprecated because it does not actually render a
+          `text/plain` response. Switch to `render plain: 'plain text'` to
+          render as `text/plain`, `render html: '<strong>HTML</strong>'` to
+          render as `text/html`, or `render body: 'raw'` to match the deprecated
+          behavior and render with the default Content-Type, which is
+          `text/plain`.
+        WARNING
+      end
+
       if options[:html]
         options[:html] = ERB::Util.html_escape(options[:html])
       end
 
       if options.delete(:nothing)
+        ActiveSupport::Deprecation.warn("`:nothing` option is deprecated and will be removed in Rails 5.1. Use `head` method to respond with empty response body.")
         options[:body] = nil
       end
 
diff --git a/actionpack/lib/action_controller/metal/request_forgery_protection.rb b/actionpack/lib/action_controller/metal/request_forgery_protection.rb
index 7facbe79aa..64f6f7cf51 100644
--- a/actionpack/lib/action_controller/metal/request_forgery_protection.rb
+++ b/actionpack/lib/action_controller/metal/request_forgery_protection.rb
@@ -13,9 +13,14 @@ module ActionController #:nodoc:
   # by including a token in the rendered HTML for your application. This token is
   # stored as a random string in the session, to which an attacker does not have
   # access. When a request reaches your application, \Rails verifies the received
-  # token with the token in the session. Only HTML and JavaScript requests are checked,
-  # so this will not protect your XML API (presumably you'll have a different
-  # authentication scheme there anyway).
+  # token with the token in the session. All requests are checked except GET requests
+  # as these should be idempotent. Keep in mind that all session-oriented requests
+  # should be CSRF protected, including JavaScript and HTML requests.
+  #
+  # Since HTML and JavaScript requests are typically made from the browser, we
+  # need to ensure to verify request authenticity for the web browser. We can
+  # use session-oriented authentication for these types of requests, by using
+  # the `protect_from_forgery` method in our controllers.
   #
   # GET requests are not protected since they don't have side effects like writing
   # to the database and don't leak sensitive information. JavaScript requests are
@@ -26,15 +31,21 @@ module ActionController #:nodoc:
   # Ajax) requests are allowed to make GET requests for JavaScript responses.
   #
   # It's important to remember that XML or JSON requests are also affected and if
-  # you're building an API you'll need something like:
+  # you're building an API you should change forgery protection method in
+  # <tt>ApplicationController</tt> (by default: <tt>:exception</tt>):
   #
   #   class ApplicationController < ActionController::Base
   #     protect_from_forgery unless: -> { request.format.json? }
   #   end
   #
-  # CSRF protection is turned on with the <tt>protect_from_forgery</tt> method,
-  # which checks the token and resets the session if it doesn't match what was expected.
-  # A call to this method is generated for new \Rails applications by default.
+  # CSRF protection is turned on with the <tt>protect_from_forgery</tt> method.
+  # By default <tt>protect_from_forgery</tt> protects your session with
+  # <tt>:null_session</tt> method, which provides an empty session
+  # during request.
+  #
+  # We may want to disable CSRF protection for APIs since they are typically
+  # designed to be state-less. That is, the request API client will handle
+  # the session for you instead of Rails.
   #
   # The token parameter is named <tt>authenticity_token</tt> by default. The name and
   # value of this token must be added to every layout that renders forms by including
@@ -79,17 +90,19 @@ module ActionController #:nodoc:
       #
       #   class FooController < ApplicationController
       #     protect_from_forgery except: :index
+      #   end
       #
       # You can disable forgery protection on controller by skipping the verification before_action:
+      #
       #   skip_before_action :verify_authenticity_token
       #
       # Valid Options:
       #
       # * <tt>:only/:except</tt> - Only apply forgery protection to a subset of actions. Like <tt>only: [ :create, :create_all ]</tt>.
-      # * <tt>:if/:unless</tt> - Turn off the forgery protection entirely depending on the passed proc or method reference.
+      # * <tt>:if/:unless</tt> - Turn off the forgery protection entirely depending on the passed Proc or method reference.
       # * <tt>:prepend</tt> - By default, the verification of the authentication token is added to the front of the
       #   callback chain. If you need to make the verification depend on other callbacks, like authentication methods
-      #   (say cookies vs oauth), this might not work for you. Pass <tt>prepend: false</tt> to just add the
+      #   (say cookies vs OAuth), this might not work for you. Pass <tt>prepend: false</tt> to just add the
       #   verification callback in the position of the protect_from_forgery call. This means any callbacks added
       #   before are run first.
       # * <tt>:with</tt> - Set the method to handle unverified request.
@@ -125,17 +138,17 @@ module ActionController #:nodoc:
         # This is the method that defines the application behavior when a request is found to be unverified.
         def handle_unverified_request
           request = @controller.request
-          request.session = NullSessionHash.new(request.env)
-          request.env['action_dispatch.request.flash_hash'] = nil
-          request.env['rack.session.options'] = { skip: true }
-          request.env['action_dispatch.cookies'] = NullCookieJar.build(request)
+          request.session = NullSessionHash.new(request)
+          request.flash = nil
+          request.session_options = { skip: true }
+          request.cookie_jar = NullCookieJar.build(request, {})
         end
 
         protected
 
         class NullSessionHash < Rack::Session::Abstract::SessionHash #:nodoc:
-          def initialize(env)
-            super(nil, env)
+          def initialize(req)
+            super(nil, req)
             @data = {}
             @loaded = true
           end
@@ -149,14 +162,6 @@ module ActionController #:nodoc:
         end
 
         class NullCookieJar < ActionDispatch::Cookies::CookieJar #:nodoc:
-          def self.build(request)
-            key_generator = request.env[ActionDispatch::Cookies::GENERATOR_KEY]
-            host          = request.host
-            secure        = request.ssl?
-
-            new(key_generator, host, secure, options_for_env({}))
-          end
-
           def write(*)
             # nothing
           end
@@ -247,7 +252,7 @@ module ActionController #:nodoc:
 
       # Returns true or false if a request is verified. Checks:
       #
-      # * is it a GET or HEAD request?  Gets should be safe and idempotent
+      # * Is it a GET or HEAD request?  Gets should be safe and idempotent
       # * Does the form_authenticity_token match the given token value from the params?
       # * Does the X-CSRF-Token header match the form_authenticity_token
       def verified_request?
@@ -275,7 +280,9 @@ module ActionController #:nodoc:
       # session token. Essentially the inverse of
       # +masked_authenticity_token+.
       def valid_authenticity_token?(session, encoded_masked_token)
-        return false if encoded_masked_token.nil? || encoded_masked_token.empty?
+        if encoded_masked_token.nil? || encoded_masked_token.empty? || !encoded_masked_token.is_a?(String)
+          return false
+        end
 
         begin
           masked_token = Base64.strict_decode64(encoded_masked_token)
diff --git a/actionpack/lib/action_controller/metal/streaming.rb b/actionpack/lib/action_controller/metal/streaming.rb
index 04401cad7b..a6115674aa 100644
--- a/actionpack/lib/action_controller/metal/streaming.rb
+++ b/actionpack/lib/action_controller/metal/streaming.rb
@@ -110,9 +110,9 @@ module ActionController #:nodoc:
   # This means that, if you have <code>yield :title</code> in your layout
   # and you want to use streaming, you would have to render the whole template
   # (and eventually trigger all queries) before streaming the title and all
-  # assets, which kills the purpose of streaming. For this reason Rails 3.1
-  # introduces a new helper called +provide+ that does the same as +content_for+
-  # but tells the layout to stop searching for other entries and continue rendering.
+  # assets, which kills the purpose of streaming. For this purpose, you can use
+  # a helper called +provide+ that does the same as +content_for+ but tells the
+  # layout to stop searching for other entries and continue rendering.
   #
   # For instance, the template above using +provide+ would be:
   #
@@ -199,7 +199,7 @@ module ActionController #:nodoc:
       def _process_options(options) #:nodoc:
         super
         if options[:stream]
-          if env["HTTP_VERSION"] == "HTTP/1.0"
+          if request.version == "HTTP/1.0"
             options.delete(:stream)
           else
             headers["Cache-Control"] ||= "no-cache"
diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index 01bbd749c1..130ba61786 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -1,7 +1,6 @@
 require 'active_support/core_ext/hash/indifferent_access'
 require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/string/filters'
-require 'active_support/deprecation'
 require 'active_support/rescuable'
 require 'action_dispatch/http/upload'
 require 'stringio'
@@ -12,9 +11,9 @@ module ActionController
   #
   #   params = ActionController::Parameters.new(a: {})
   #   params.fetch(:b)
-  #   # => ActionController::ParameterMissing: param not found: b
+  #   # => ActionController::ParameterMissing: param is missing or the value is empty: b
   #   params.require(:a)
-  #   # => ActionController::ParameterMissing: param not found: a
+  #   # => ActionController::ParameterMissing: param is missing or the value is empty: a
   class ParameterMissing < KeyError
     attr_reader :param # :nodoc:
 
@@ -24,11 +23,13 @@ module ActionController
     end
   end
 
-  # Raised when a supplied parameter is not expected.
+  # Raised when a supplied parameter is not expected and
+  # ActionController::Parameters.action_on_unpermitted_parameters
+  # is set to <tt>:raise</tt>.
   #
   #   params = ActionController::Parameters.new(a: "123", b: "456")
   #   params.permit(:c)
-  #   # => ActionController::UnpermittedParameters: found unexpected keys: a, b
+  #   # => ActionController::UnpermittedParameters: found unpermitted parameters: a, b
   class UnpermittedParameters < IndexError
     attr_reader :params # :nodoc:
 
@@ -96,17 +97,18 @@ module ActionController
   # environment they should only be set once at boot-time and never mutated at
   # runtime.
   #
-  # <tt>ActionController::Parameters</tt> inherits from
-  # <tt>ActiveSupport::HashWithIndifferentAccess</tt>, this means
-  # that you can fetch values using either <tt>:key</tt> or <tt>"key"</tt>.
+  # You can fetch values of <tt>ActionController::Parameters</tt> using either
+  # <tt>:key</tt> or <tt>"key"</tt>.
   #
   #   params = ActionController::Parameters.new(key: 'value')
   #   params[:key]  # => "value"
   #   params["key"] # => "value"
-  class Parameters < ActiveSupport::HashWithIndifferentAccess
+  class Parameters
     cattr_accessor :permit_all_parameters, instance_accessor: false
     cattr_accessor :action_on_unpermitted_parameters, instance_accessor: false
 
+    delegate :keys, :key?, :has_key?, :empty?, :inspect, to: :@parameters
+
     # By default, never raise an UnpermittedParameters exception if these
     # params are present. The default includes both 'controller' and 'action'
     # because they are added by Rails and should be of no concern. One way
@@ -118,7 +120,7 @@ module ActionController
     self.always_permitted_parameters = %w( controller action )
 
     def self.const_missing(const_name)
-      super unless const_name == :NEVER_UNPERMITTED_PARAMS
+      return super unless const_name == :NEVER_UNPERMITTED_PARAMS
       ActiveSupport::Deprecation.warn(<<-MSG.squish)
         `ActionController::Parameters::NEVER_UNPERMITTED_PARAMS` has been deprecated.
         Use `ActionController::Parameters.always_permitted_parameters` instead.
@@ -143,11 +145,22 @@ module ActionController
     #   params = ActionController::Parameters.new(name: 'Francesco')
     #   params.permitted?  # => true
     #   Person.new(params) # => #<Person id: nil, name: "Francesco">
-    def initialize(attributes = nil)
-      super(attributes)
+    def initialize(parameters = {})
+      @parameters = parameters.with_indifferent_access
       @permitted = self.class.permit_all_parameters
     end
 
+    # Returns true if another +Parameters+ object contains the same content and
+    # permitted flag, or other Hash-like object contains the same content. This
+    # override is in place so you can perform a comparison with `Hash`.
+    def ==(other_hash)
+      if other_hash.respond_to?(:permitted?)
+        super
+      else
+        @parameters == other_hash
+      end
+    end
+
     # Returns a safe +Hash+ representation of this parameter with all
     # unpermitted keys removed.
     #
@@ -161,7 +174,7 @@ module ActionController
     #   safe_params.to_h # => {"name"=>"Senjougahara Hitagi"}
     def to_h
       if permitted?
-        to_hash
+        @parameters.to_h
       else
         slice(*self.class.always_permitted_parameters).permit!.to_h
       end
@@ -169,20 +182,17 @@ module ActionController
 
     # Returns an unsafe, unfiltered +Hash+ representation of this parameter.
     def to_unsafe_h
-      to_hash
+      @parameters.to_h
     end
     alias_method :to_unsafe_hash, :to_unsafe_h
 
     # Convert all hashes in values into parameters, then yield each pair like
     # the same way as <tt>Hash#each_pair</tt>
     def each_pair(&block)
-      super do |key, value|
-        convert_hashes_to_parameters(key, value)
+      @parameters.each_pair do |key, value|
+        yield key, convert_hashes_to_parameters(key, value)
       end
-
-      super
     end
-
     alias_method :each, :each_pair
 
     # Attribute that keeps track of converted arrays, if any, to avoid double
@@ -229,19 +239,58 @@ module ActionController
       self
     end
 
-    # Ensures that a parameter is present. If it's present, returns
-    # the parameter at the given +key+, otherwise raises an
-    # <tt>ActionController::ParameterMissing</tt> error.
+    # This method accepts both a single key and an array of keys.
+    #
+    # When passed a single key, if it exists and its associated value is
+    # either present or the singleton +false+, returns said value:
     #
     #   ActionController::Parameters.new(person: { name: 'Francesco' }).require(:person)
     #   # => {"name"=>"Francesco"}
     #
+    # Otherwise raises <tt>ActionController::ParameterMissing</tt>:
+    #
+    #   ActionController::Parameters.new.require(:person)
+    #   # ActionController::ParameterMissing: param is missing or the value is empty: person
+    #
     #   ActionController::Parameters.new(person: nil).require(:person)
-    #   # => ActionController::ParameterMissing: param not found: person
+    #   # ActionController::ParameterMissing: param is missing or the value is empty: person
+    #
+    #   ActionController::Parameters.new(person: "\t").require(:person)
+    #   # ActionController::ParameterMissing: param is missing or the value is empty: person
     #
     #   ActionController::Parameters.new(person: {}).require(:person)
-    #   # => ActionController::ParameterMissing: param not found: person
+    #   # ActionController::ParameterMissing: param is missing or the value is empty: person
+    #
+    # When given an array of keys, the method tries to require each one of them
+    # in order. If it succeeds, an array with the respective return values is
+    # returned:
+    #
+    #   params = ActionController::Parameters.new(user: { ... }, profile: { ... })
+    #   user_params, profile_params = params.require(:user, :profile)
+    #
+    # Otherwise, the method reraises the first exception found:
+    #
+    #   params = ActionController::Parameters.new(user: {}, profile: {})
+    #   user_params, profile_params = params.require(:user, :profile)
+    #   # ActionController::ParameterMissing: param is missing or the value is empty: user
+    #
+    # Technically this method can be used to fetch terminal values:
+    #
+    #   # CAREFUL
+    #   params = ActionController::Parameters.new(person: { name: 'Finn' })
+    #   name = params.require(:person).require(:name) # CAREFUL
+    #
+    # but take into account that at some point those ones have to be permitted:
+    #
+    #   def person_params
+    #     params.require(:person).permit(:name).tap do |person_params|
+    #       person_params.require(:name) # SAFER
+    #     end
+    #   end
+    #
+    # for example.
     def require(key)
+      return key.map { |k| require(k) } if key.is_a?(Array)
       value = self[key]
       if value.present? || value == false
         value
@@ -269,7 +318,7 @@ module ActionController
     #
     #   params.permit(:name)
     #
-    # +:name+ passes it is a key of +params+ whose associated value is of type
+    # +:name+ passes if it is a key of +params+ whose associated value is of type
     # +String+, +Symbol+, +NilClass+, +Numeric+, +TrueClass+, +FalseClass+,
     # +Date+, +Time+, +DateTime+, +StringIO+, +IO+,
     # +ActionDispatch::Http::UploadedFile+ or +Rack::Test::UploadedFile+.
@@ -346,7 +395,13 @@ module ActionController
     #   params[:person] # => {"name"=>"Francesco"}
     #   params[:none]   # => nil
     def [](key)
-      convert_hashes_to_parameters(key, super)
+      convert_hashes_to_parameters(key, @parameters[key])
+    end
+
+    # Assigns a value to a given +key+. The given key may still get filtered out
+    # when +permit+ is called.
+    def []=(key, value)
+      @parameters[key] = value
     end
 
     # Returns a parameter for the given +key+. If the +key+
@@ -357,13 +412,19 @@ module ActionController
     #
     #   params = ActionController::Parameters.new(person: { name: 'Francesco' })
     #   params.fetch(:person)               # => {"name"=>"Francesco"}
-    #   params.fetch(:none)                 # => ActionController::ParameterMissing: param not found: none
+    #   params.fetch(:none)                 # => ActionController::ParameterMissing: param is missing or the value is empty: none
     #   params.fetch(:none, 'Francesco')    # => "Francesco"
     #   params.fetch(:none) { 'Francesco' } # => "Francesco"
-    def fetch(key, *args)
-      convert_hashes_to_parameters(key, super, false)
-    rescue KeyError
-      raise ActionController::ParameterMissing.new(key)
+    def fetch(key, *args, &block)
+      convert_value_to_parameters(
+        @parameters.fetch(key) {
+          if block_given?
+            yield
+          else
+            args.fetch(0) { raise ActionController::ParameterMissing.new(key) }
+          end
+        }
+      )
     end
 
     # Returns a new <tt>ActionController::Parameters</tt> instance that
@@ -374,7 +435,24 @@ module ActionController
     #   params.slice(:a, :b) # => {"a"=>1, "b"=>2}
     #   params.slice(:d)     # => {}
     def slice(*keys)
-      new_instance_with_inherited_permitted_status(super)
+      new_instance_with_inherited_permitted_status(@parameters.slice(*keys))
+    end
+
+    # Returns current <tt>ActionController::Parameters</tt> instance which
+    # contains only the given +keys+.
+    def slice!(*keys)
+      @parameters.slice!(*keys)
+      self
+    end
+
+    # Returns a new <tt>ActionController::Parameters</tt> instance that
+    # filters out the given +keys+.
+    #
+    #   params = ActionController::Parameters.new(a: 1, b: 2, c: 3)
+    #   params.except(:a, :b) # => {"c"=>3}
+    #   params.except(:d)     # => {"a"=>1,"b"=>2,"c"=>3}
+    def except(*keys)
+      new_instance_with_inherited_permitted_status(@parameters.except(*keys))
     end
 
     # Removes and returns the key/value pairs matching the given keys.
@@ -383,7 +461,7 @@ module ActionController
     #   params.extract!(:a, :b) # => {"a"=>1, "b"=>2}
     #   params                  # => {"c"=>3}
     def extract!(*keys)
-      new_instance_with_inherited_permitted_status(super)
+      new_instance_with_inherited_permitted_status(@parameters.extract!(*keys))
     end
 
     # Returns a new <tt>ActionController::Parameters</tt> with the results of
@@ -392,36 +470,80 @@ module ActionController
     #   params = ActionController::Parameters.new(a: 1, b: 2, c: 3)
     #   params.transform_values { |x| x * 2 }
     #   # => {"a"=>2, "b"=>4, "c"=>6}
-    def transform_values
-      if block_given?
-        new_instance_with_inherited_permitted_status(super)
+    def transform_values(&block)
+      if block
+        new_instance_with_inherited_permitted_status(
+          @parameters.transform_values(&block)
+        )
       else
-        super
+        @parameters.transform_values
       end
     end
 
-    # This method is here only to make sure that the returned object has the
-    # correct +permitted+ status. It should not matter since the parent of
-    # this object is +HashWithIndifferentAccess+
-    def transform_keys # :nodoc:
-      if block_given?
-        new_instance_with_inherited_permitted_status(super)
+    # Performs values transformation and returns the altered
+    # <tt>ActionController::Parameters</tt> instance.
+    def transform_values!(&block)
+      @parameters.transform_values!(&block)
+      self
+    end
+
+    # Returns a new <tt>ActionController::Parameters</tt> instance with the
+    # results of running +block+ once for every key. The values are unchanged.
+    def transform_keys(&block)
+      if block
+        new_instance_with_inherited_permitted_status(
+          @parameters.transform_keys(&block)
+        )
       else
-        super
+        @parameters.transform_keys
       end
     end
 
+    # Performs keys transformation and returns the altered
+    # <tt>ActionController::Parameters</tt> instance.
+    def transform_keys!(&block)
+      @parameters.transform_keys!(&block)
+      self
+    end
+
     # Deletes and returns a key-value pair from +Parameters+ whose key is equal
     # to key. If the key is not found, returns the default value. If the
     # optional code block is given and the key is not found, pass in the key
     # and return the result of block.
     def delete(key, &block)
-      convert_hashes_to_parameters(key, super, false)
+      convert_value_to_parameters(@parameters.delete(key))
+    end
+
+    # Returns a new instance of <tt>ActionController::Parameters</tt> with only
+    # items that the block evaluates to true.
+    def select(&block)
+      new_instance_with_inherited_permitted_status(@parameters.select(&block))
     end
 
     # Equivalent to Hash#keep_if, but returns nil if no changes were made.
     def select!(&block)
-      convert_value_to_parameters(super)
+      @parameters.select!(&block)
+      self
+    end
+    alias_method :keep_if, :select!
+
+    # Returns a new instance of <tt>ActionController::Parameters</tt> with items
+    # that the block evaluates to true removed.
+    def reject(&block)
+      new_instance_with_inherited_permitted_status(@parameters.reject(&block))
+    end
+
+    # Removes items that the block evaluates to true and returns self.
+    def reject!(&block)
+      @parameters.reject!(&block)
+      self
+    end
+    alias_method :delete_if, :reject!
+
+    # Returns values that were assigned to the given +keys+. Note that all the
+    # +Hash+ objects will be converted to <tt>ActionController::Parameters</tt>.
+    def values_at(*keys)
+      convert_value_to_parameters(@parameters.values_at(*keys))
     end
 
     # Returns an exact copy of the <tt>ActionController::Parameters</tt>
@@ -438,11 +560,30 @@ module ActionController
       end
     end
 
+    # Returns a new <tt>ActionController::Parameters</tt> with all keys from
+    # +other_hash+ merges into current hash.
+    def merge(other_hash)
+      new_instance_with_inherited_permitted_status(
+        @parameters.merge(other_hash)
+      )
+    end
+
+    # This is required by ActiveModel attribute assignment, so that user can
+    # pass +Parameters+ to a mass assignment methods in a model. It should not
+    # matter as we are using +HashWithIndifferentAccess+ internally.
+    def stringify_keys # :nodoc:
+      dup
+    end
+
     protected
       def permitted=(new_permitted)
         @permitted = new_permitted
       end
 
+      def fields_for_style?
+        @parameters.all? { |k, v| k =~ /\A-?\d+\z/ && v.is_a?(Hash) }
+      end
+
     private
       def new_instance_with_inherited_permitted_status(hash)
         self.class.new(hash).tap do |new_instance|
@@ -450,40 +591,41 @@ module ActionController
         end
       end
 
-      def convert_hashes_to_parameters(key, value, assign_if_converted=true)
+      def convert_hashes_to_parameters(key, value)
         converted = convert_value_to_parameters(value)
-        self[key] = converted if assign_if_converted && !converted.equal?(value)
+        @parameters[key] = converted unless converted.equal?(value)
         converted
       end
 
       def convert_value_to_parameters(value)
-        if value.is_a?(Array) && !converted_arrays.member?(value)
+        case value
+        when Array
+          return value if converted_arrays.member?(value)
           converted = value.map { |_| convert_value_to_parameters(_) }
           converted_arrays << converted
           converted
-        elsif value.is_a?(Parameters) || !value.is_a?(Hash)
-          value
-        else
+        when Hash
           self.class.new(value)
+        else
+          value
         end
       end
 
       def each_element(object)
-        if object.is_a?(Array)
-          object.map { |el| yield el }.compact
-        elsif fields_for_style?(object)
-          hash = object.class.new
-          object.each { |k,v| hash[k] = yield v }
-          hash
-        else
-          yield object
+        case object
+        when Array
+          object.grep(Parameters).map { |el| yield el }.compact
+        when Parameters
+          if object.fields_for_style?
+            hash = object.class.new
+            object.each { |k,v| hash[k] = yield v }
+            hash
+          else
+            yield object
+          end
         end
       end
 
-      def fields_for_style?(object)
-        object.is_a?(Hash) && object.all? { |k, v| k =~ /\A-?\d+\z/ && v.is_a?(Hash) }
-      end
-
       def unpermitted_parameters!(params)
         unpermitted_keys = unpermitted_keys(params)
         if unpermitted_keys.any?
@@ -545,14 +687,8 @@ module ActionController
       end
 
       def array_of_permitted_scalars?(value)
-        if value.is_a?(Array)
-          value.all? {|element| permitted_scalar?(element)}
-        end
-      end
-
-      def array_of_permitted_scalars_filter(params, key)
-        if has_key?(key) && array_of_permitted_scalars?(self[key])
-          params[key] = self[key]
+        if value.is_a?(Array) && value.all? {|element| permitted_scalar?(element)}
+          yield value
         end
       end
 
@@ -563,17 +699,17 @@ module ActionController
         # Slicing filters out non-declared keys.
         slice(*filter.keys).each do |key, value|
           next unless value
+          next unless has_key? key
 
           if filter[key] == EMPTY_ARRAY
             # Declaration { comment_ids: [] }.
-            array_of_permitted_scalars_filter(params, key)
+            array_of_permitted_scalars?(self[key]) do |val|
+              params[key] = val
+            end
           else
             # Declaration { user: :name } or { user: [:name, :age, { address: ... }] }.
             params[key] = each_element(value) do |element|
-              if element.is_a?(Hash)
-                element = self.class.new(element) unless element.respond_to?(:permit)
-                element.permit(*Array.wrap(filter[key]))
-              end
+              element.permit(*Array.wrap(filter[key]))
             end
           end
         end
diff --git a/actionpack/lib/action_controller/metal/testing.rb b/actionpack/lib/action_controller/metal/testing.rb
index d01927b7cb..b2b3b4283f 100644
--- a/actionpack/lib/action_controller/metal/testing.rb
+++ b/actionpack/lib/action_controller/metal/testing.rb
@@ -2,14 +2,6 @@ module ActionController
   module Testing
     extend ActiveSupport::Concern
 
-    include RackDelegation
-
-    # TODO : Rewrite tests using controller.headers= to use Rack env
-    def headers=(new_headers)
-      @_response ||= ActionDispatch::Response.new
-      @_response.headers.replace(new_headers)
-    end
-
     # Behavior specific to functional tests
     module Functional # :nodoc:
       def set_response!(request)
diff --git a/actionpack/lib/action_controller/metal/url_for.rb b/actionpack/lib/action_controller/metal/url_for.rb
index 572d1770f7..dbf7241a14 100644
--- a/actionpack/lib/action_controller/metal/url_for.rb
+++ b/actionpack/lib/action_controller/metal/url_for.rb
@@ -4,7 +4,10 @@ module ActionController
   #
   # In addition to <tt>AbstractController::UrlFor</tt>, this module accesses the HTTP layer to define
   # url options like the +host+. In order to do so, this module requires the host class
-  # to implement +env+ and +request+, which need to be a Rack-compatible.
+  # to implement +env+ which needs to be Rack-compatible and +request+
+  # which is either an instance of +ActionDispatch::Request+ or an object
+  # that responds to the +host+, +optional_port+, +protocol+ and
+  # +symbolized_path_parameter+ methods.
   #
   #   class RootUrl
   #     include ActionController::UrlFor
@@ -38,7 +41,11 @@ module ActionController
         if original_script_name
           options[:original_script_name] = original_script_name
         else
-          options[:script_name] = same_origin ? request.script_name.dup : script_name
+          if same_origin
+            options[:script_name] = request.script_name.empty? ? "".freeze : request.script_name.dup
+          else
+            options[:script_name] = script_name
+          end
         end
         options.freeze
       else
diff --git a/actionpack/lib/action_controller/middleware.rb b/actionpack/lib/action_controller/middleware.rb
deleted file mode 100644
index 437fec3dc6..0000000000
--- a/actionpack/lib/action_controller/middleware.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-module ActionController
-  class Middleware < Metal
-    class ActionMiddleware
-      def initialize(controller, app)
-        @controller, @app = controller, app
-      end
-
-      def call(env)
-        request = ActionDispatch::Request.new(env)
-        @controller.build(@app).dispatch(:index, request)
-      end
-    end
-
-    class << self
-      alias build new
-
-      def new(app)
-        ActionMiddleware.new(self, app)
-      end
-    end
-
-    attr_internal :app
-
-    def process(action)
-      response = super
-      self.status, self.headers, self.response_body = response if response.is_a?(Array)
-      response
-    end
-
-    def initialize(app)
-      super()
-      @_app = app
-    end
-
-    def index
-      call(env)
-    end
-  end
-end
\ No newline at end of file
diff --git a/actionpack/lib/action_controller/renderer.rb b/actionpack/lib/action_controller/renderer.rb
new file mode 100644
index 0000000000..e4d19e9dba
--- /dev/null
+++ b/actionpack/lib/action_controller/renderer.rb
@@ -0,0 +1,111 @@
+require 'active_support/core_ext/hash/keys'
+
+module ActionController
+  # ActionController::Renderer allows to render arbitrary templates
+  # without requirement of being in controller actions.
+  #
+  # You get a concrete renderer class by invoking ActionController::Base#renderer.
+  # For example,
+  #
+  #   ApplicationController.renderer
+  #
+  # It allows you to call method #render directly.
+  #
+  #   ApplicationController.renderer.render template: '...'
+  #
+  # You can use a shortcut on controller to replace previous example with:
+  #
+  #   ApplicationController.render template: '...'
+  #
+  # #render method allows you to use any options as when rendering in controller.
+  # For example,
+  #
+  #   FooController.render :action, locals: { ... }, assigns: { ... }
+  #
+  # The template will be rendered in a Rack environment which is accessible through
+  # ActionController::Renderer#env. You can set it up in two ways:
+  #
+  # *  by changing renderer defaults, like
+  #
+  #       ApplicationController.renderer.defaults # => hash with default Rack environment
+  #
+  # *  by initializing an instance of renderer by passing it a custom environment.
+  #
+  #       ApplicationController.renderer.new(method: 'post', https: true)
+  #
+  class Renderer
+    attr_reader :defaults, :controller
+
+    DEFAULTS = {
+      http_host: 'example.org',
+      https: false,
+      method: 'get',
+      script_name: '',
+      input: ''
+    }.freeze
+
+    # Create a new renderer instance for a specific controller class.
+    def self.for(controller, env = {}, defaults = DEFAULTS)
+      new(controller, env, defaults)
+    end
+
+    # Create a new renderer for the same controller but with a new env.
+    def new(env = {})
+      self.class.new controller, env, defaults
+    end
+
+    # Create a new renderer for the same controller but with new defaults.
+    def with_defaults(defaults)
+      self.class.new controller, env, self.defaults.merge(defaults)
+    end
+
+    # Accepts a custom Rack environment to render templates in.
+    # It will be merged with ActionController::Renderer.defaults
+    def initialize(controller, env, defaults)
+      @controller = controller
+      @defaults = defaults
+      @env = normalize_keys defaults.merge(env)
+    end
+
+    # Render templates with any options from ActionController::Base#render_to_string.
+    def render(*args)
+      raise 'missing controller' unless controller
+
+      request = ActionDispatch::Request.new @env
+      request.routes = controller._routes
+
+      instance = controller.new
+      instance.set_request! request
+      instance.set_response! controller.make_response!(request)
+      instance.render_to_string(*args)
+    end
+
+    private
+      def normalize_keys(env)
+        new_env = {}
+        env.each_pair { |k,v| new_env[rack_key_for(k)] = rack_value_for(k, v) }
+        new_env
+      end
+
+      RACK_KEY_TRANSLATION = {
+        http_host:   'HTTP_HOST',
+        https:       'HTTPS',
+        method:      'REQUEST_METHOD',
+        script_name: 'SCRIPT_NAME',
+        input:       'rack.input'
+      }
+
+      IDENTITY = ->(_) { _ }
+
+      RACK_VALUE_TRANSLATION = {
+        https: ->(v) { v ? 'on' : 'off' },
+        method: ->(v) { v.upcase },
+      }
+
+      def rack_key_for(key); RACK_KEY_TRANSLATION[key]; end
+
+      def rack_value_for(key, value)
+        RACK_VALUE_TRANSLATION.fetch(key, IDENTITY).call value
+      end
+  end
+end
diff --git a/actionpack/lib/action_controller/template_assertions.rb b/actionpack/lib/action_controller/template_assertions.rb
new file mode 100644
index 0000000000..0179f4afcd
--- /dev/null
+++ b/actionpack/lib/action_controller/template_assertions.rb
@@ -0,0 +1,9 @@
+module ActionController
+  module TemplateAssertions
+    def assert_template(options = {}, message = nil)
+      raise NoMethodError,
+        "assert_template has been extracted to a gem. To continue using it,
+        add `gem 'rails-controller-testing'` to your Gemfile."
+    end
+  end
+end
diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index d30615fade..2cada1f68a 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -1,223 +1,57 @@
 require 'rack/session/abstract/id'
+require 'active_support/core_ext/hash/conversions'
 require 'active_support/core_ext/object/to_query'
 require 'active_support/core_ext/module/anonymous'
 require 'active_support/core_ext/hash/keys'
-
+require 'action_controller/template_assertions'
 require 'rails-dom-testing'
 
 module ActionController
-  module TemplateAssertions
-    extend ActiveSupport::Concern
+  class TestRequest < ActionDispatch::TestRequest #:nodoc:
+    DEFAULT_ENV = ActionDispatch::TestRequest::DEFAULT_ENV.dup
+    DEFAULT_ENV.delete 'PATH_INFO'
 
-    included do
-      setup :setup_subscriptions
-      teardown :teardown_subscriptions
+    def self.new_session
+      TestSession.new
     end
 
-    RENDER_TEMPLATE_INSTANCE_VARIABLES = %w{partials templates layouts files}.freeze
-
-    def setup_subscriptions
-      RENDER_TEMPLATE_INSTANCE_VARIABLES.each do |instance_variable|
-        instance_variable_set("@_#{instance_variable}", Hash.new(0))
-      end
-
-      @_subscribers = []
-
-      @_subscribers << ActiveSupport::Notifications.subscribe("render_template.action_view") do |_name, _start, _finish, _id, payload|
-        path = payload[:layout]
-        if path
-          @_layouts[path] += 1
-          if path =~ /^layouts\/(.*)/
-            @_layouts[$1] += 1
-          end
-        end
-      end
-
-      @_subscribers << ActiveSupport::Notifications.subscribe("!render_template.action_view") do |_name, _start, _finish, _id, payload|
-        if virtual_path = payload[:virtual_path]
-          partial = virtual_path =~ /^.*\/_[^\/]*$/
-
-          if partial
-            @_partials[virtual_path] += 1
-            @_partials[virtual_path.split("/").last] += 1
-          end
-
-          @_templates[virtual_path] += 1
-        else
-          path = payload[:identifier]
-          if path
-            @_files[path] += 1
-            @_files[path.split("/").last] += 1
-          end
-        end
-      end
+    # Create a new test request with default `env` values
+    def self.create
+      env = {}
+      env = Rails.application.env_config.merge(env) if defined?(Rails.application) && Rails.application
+      env["rack.request.cookie_hash"] = {}.with_indifferent_access
+      new(default_env.merge(env), new_session)
     end
 
-    def teardown_subscriptions
-      @_subscribers.each do |subscriber|
-        ActiveSupport::Notifications.unsubscribe(subscriber)
-      end
+    def self.default_env
+      DEFAULT_ENV
     end
+    private_class_method :default_env
 
-    def process(*args)
-      reset_template_assertion
-      super
-    end
+    def initialize(env, session)
+      super(env)
 
-    def reset_template_assertion
-      RENDER_TEMPLATE_INSTANCE_VARIABLES.each do |instance_variable|
-        ivar_name = "@_#{instance_variable}"
-        if instance_variable_defined?(ivar_name)
-          instance_variable_get(ivar_name).clear
-        end
-      end
+      self.session = session
+      self.session_options = TestSession::DEFAULT_OPTIONS
+      @custom_param_parsers = {
+        Mime[:xml] => lambda { |raw_post| Hash.from_xml(raw_post)['hash'] }
+      }
     end
 
-    # Asserts that the request was rendered with the appropriate template file or partials.
-    #
-    #   # assert that the "new" view template was rendered
-    #   assert_template "new"
-    #
-    #   # assert that the exact template "admin/posts/new" was rendered
-    #   assert_template %r{\Aadmin/posts/new\Z}
-    #
-    #   # assert that the layout 'admin' was rendered
-    #   assert_template layout: 'admin'
-    #   assert_template layout: 'layouts/admin'
-    #   assert_template layout: :admin
-    #
-    #   # assert that no layout was rendered
-    #   assert_template layout: nil
-    #   assert_template layout: false
-    #
-    #   # assert that the "_customer" partial was rendered twice
-    #   assert_template partial: '_customer', count: 2
-    #
-    #   # assert that no partials were rendered
-    #   assert_template partial: false
-    #
-    #   # assert that a file was rendered
-    #   assert_template file: "README.rdoc"
-    #
-    #   # assert that no file was rendered
-    #   assert_template file: nil
-    #   assert_template file: false
-    #
-    # In a view test case, you can also assert that specific locals are passed
-    # to partials:
-    #
-    #   # assert that the "_customer" partial was rendered with a specific object
-    #   assert_template partial: '_customer', locals: { customer: @customer }
-    def assert_template(options = {}, message = nil)
-      # Force body to be read in case the template is being streamed.
-      response.body
-
-      case options
-      when NilClass, Regexp, String, Symbol
-        options = options.to_s if Symbol === options
-        rendered = @_templates
-        msg = message || sprintf("expecting <%s> but rendering with <%s>",
-                options.inspect, rendered.keys)
-        matches_template =
-          case options
-          when String
-            !options.empty? && rendered.any? do |t, num|
-              options_splited = options.split(File::SEPARATOR)
-              t_splited = t.split(File::SEPARATOR)
-              t_splited.last(options_splited.size) == options_splited
-            end
-          when Regexp
-            rendered.any? { |t,num| t.match(options) }
-          when NilClass
-            rendered.blank?
-          end
-        assert matches_template, msg
-      when Hash
-        options.assert_valid_keys(:layout, :partial, :locals, :count, :file)
-
-        if options.key?(:layout)
-          expected_layout = options[:layout]
-          msg = message || sprintf("expecting layout <%s> but action rendered <%s>",
-                  expected_layout, @_layouts.keys)
-
-          case expected_layout
-          when String, Symbol
-            assert_includes @_layouts.keys, expected_layout.to_s, msg
-          when Regexp
-            assert(@_layouts.keys.any? {|l| l =~ expected_layout }, msg)
-          when nil, false
-            assert(@_layouts.empty?, msg)
-          else
-            raise ArgumentError, "assert_template only accepts a String, Symbol, Regexp, nil or false for :layout"
-          end
-        end
-
-        if options[:file]
-          assert_includes @_files.keys, options[:file]
-        elsif options.key?(:file)
-          assert @_files.blank?, "expected no files but #{@_files.keys} was rendered"
-        end
-
-        if expected_partial = options[:partial]
-          if expected_locals = options[:locals]
-            if defined?(@_rendered_views)
-              view = expected_partial.to_s.sub(/^_/, '').sub(/\/_(?=[^\/]+\z)/, '/')
-
-              partial_was_not_rendered_msg = "expected %s to be rendered but it was not." % view
-              assert_includes @_rendered_views.rendered_views, view, partial_was_not_rendered_msg
-
-              msg = 'expecting %s to be rendered with %s but was with %s' % [expected_partial,
-                                                                             expected_locals,
-                                                                             @_rendered_views.locals_for(view)]
-              assert(@_rendered_views.view_rendered?(view, options[:locals]), msg)
-            else
-              warn "the :locals option to #assert_template is only supported in a ActionView::TestCase"
-            end
-          elsif expected_count = options[:count]
-            actual_count = @_partials[expected_partial]
-            msg = message || sprintf("expecting %s to be rendered %s time(s) but rendered %s time(s)",
-                     expected_partial, expected_count, actual_count)
-            assert(actual_count == expected_count.to_i, msg)
-          else
-            msg = message || sprintf("expecting partial <%s> but action rendered <%s>",
-                    options[:partial], @_partials.keys)
-            assert_includes @_partials, expected_partial, msg
-          end
-        elsif options.key?(:partial)
-          assert @_partials.empty?,
-            "Expected no partials to be rendered"
-        end
-      else
-        raise ArgumentError, "assert_template only accepts a String, Symbol, Hash, Regexp, or nil"
-      end
+    def query_string=(string)
+      set_header Rack::QUERY_STRING, string
     end
-  end
 
-  class TestRequest < ActionDispatch::TestRequest #:nodoc:
-    DEFAULT_ENV = ActionDispatch::TestRequest::DEFAULT_ENV.dup
-    DEFAULT_ENV.delete 'PATH_INFO'
-
-    def initialize(env = {})
-      super
-
-      self.session = TestSession.new
-      self.session_options = TestSession::DEFAULT_OPTIONS.merge(:id => SecureRandom.hex(16))
+    def content_type=(type)
+      set_header 'CONTENT_TYPE', type
     end
 
-    def assign_parameters(routes, controller_path, action, parameters = {})
-      parameters = parameters.symbolize_keys.merge(:controller => controller_path, :action => action)
-      extra_keys = routes.extra_keys(parameters)
-      non_path_parameters = get? ? query_parameters : request_parameters
-      parameters.each do |key, value|
-        if value.is_a?(Array) && (value.frozen? || value.any?(&:frozen?))
-          value = value.map{ |v| v.duplicable? ? v.dup : v }
-        elsif value.is_a?(Hash) && (value.frozen? || value.any?{ |k,v| v.frozen? })
-          value = Hash[value.map{ |k,v| [k, v.duplicable? ? v.dup : v] }]
-        elsif value.frozen? && value.duplicable?
-          value = value.dup
-        end
+    def assign_parameters(routes, controller_path, action, parameters, generated_path, query_string_keys)
+      non_path_parameters = {}
+      path_parameters = {}
 
-        if extra_keys.include?(key)
+      parameters.each do |key, value|
+        if query_string_keys.include?(key)
           non_path_parameters[key] = value
         else
           if value.is_a?(Array)
@@ -230,72 +64,88 @@ module ActionController
         end
       end
 
-      # Clear the combined params hash in case it was already referenced.
-      @env.delete("action_dispatch.request.parameters")
+      if get?
+        if self.query_string.blank?
+          self.query_string = non_path_parameters.to_query
+        end
+      else
+        if ENCODER.should_multipart?(non_path_parameters)
+          self.content_type = ENCODER.content_type
+          data = ENCODER.build_multipart non_path_parameters
+        else
+          fetch_header('CONTENT_TYPE') do |k|
+            set_header k, 'application/x-www-form-urlencoded'
+          end
 
-      # Clear the filter cache variables so they're not stale
-      @filtered_parameters = @filtered_env = @filtered_path = nil
+          case content_mime_type.to_sym
+          when nil
+            raise "Unknown Content-Type: #{content_type}"
+          when :json
+            data = ActiveSupport::JSON.encode(non_path_parameters)
+          when :xml
+            data = non_path_parameters.to_xml
+          when :url_encoded_form
+            data = non_path_parameters.to_query
+          else
+            @custom_param_parsers[content_mime_type] = ->(_) { non_path_parameters }
+            data = non_path_parameters.to_query
+          end
+        end
 
-      params = self.request_parameters.dup
-      %w(controller action only_path).each do |k|
-        params.delete(k)
-        params.delete(k.to_sym)
+        set_header 'CONTENT_LENGTH', data.length.to_s
+        set_header 'rack.input', StringIO.new(data)
       end
-      data = params.to_query
 
-      @env['CONTENT_LENGTH'] = data.length.to_s
-      @env['rack.input'] = StringIO.new(data)
-    end
+      fetch_header("PATH_INFO") do |k|
+        set_header k, generated_path
+      end
+      path_parameters[:controller] = controller_path
+      path_parameters[:action] = action
 
-    def recycle!
-      @formats = nil
-      @env.delete_if { |k, v| k =~ /^(action_dispatch|rack)\.request/ }
-      @env.delete_if { |k, v| k =~ /^action_dispatch\.rescue/ }
-      @method = @request_method = nil
-      @fullpath = @ip = @remote_ip = @protocol = nil
-      @env['action_dispatch.request.query_parameters'] = {}
-      @set_cookies ||= {}
-      @set_cookies.update(Hash[cookie_jar.instance_variable_get("@set_cookies").map{ |k,o| [k,o[:value]] }])
-      deleted_cookies = cookie_jar.instance_variable_get("@delete_cookies")
-      @set_cookies.reject!{ |k,v| deleted_cookies.include?(k) }
-      cookie_jar.update(rack_cookies)
-      cookie_jar.update(cookies)
-      cookie_jar.update(@set_cookies)
-      cookie_jar.recycle!
+      self.path_parameters = path_parameters
     end
 
-    private
+    ENCODER = Class.new do
+      include Rack::Test::Utils
+
+      def should_multipart?(params)
+        # FIXME: lifted from Rack-Test. We should push this separation upstream
+        multipart = false
+        query = lambda { |value|
+          case value
+          when Array
+            value.each(&query)
+          when Hash
+            value.values.each(&query)
+          when Rack::Test::UploadedFile
+            multipart = true
+          end
+        }
+        params.values.each(&query)
+        multipart
+      end
 
-    def default_env
-      DEFAULT_ENV
-    end
-  end
+      public :build_multipart
 
-  class TestResponse < ActionDispatch::TestResponse
-    def recycle!
-      initialize
-    end
-  end
+      def content_type
+        "multipart/form-data; boundary=#{Rack::Test::MULTIPART_BOUNDARY}"
+      end
+    end.new
 
-  class LiveTestResponse < Live::Response
-    def recycle!
-      @body = nil
-      initialize
-    end
+    private
 
-    def body
-      @body ||= super
+    def params_parsers
+      super.merge @custom_param_parsers
     end
+  end
 
+  class LiveTestResponse < Live::Response
     # Was the response successful?
     alias_method :success?, :successful?
 
     # Was the URL not found?
     alias_method :missing?, :not_found?
 
-    # Were we redirected?
-    alias_method :redirect?, :redirection?
-
     # Was there a server-side error?
     alias_method :error?, :server_error?
   end
@@ -303,7 +153,7 @@ module ActionController
   # Methods #destroy and #load! are overridden to avoid calling methods on the
   # @store object, which does not exist for the TestSession class.
   class TestSession < Rack::Session::Abstract::SessionHash #:nodoc:
-    DEFAULT_OPTIONS = Rack::Session::Abstract::ID::DEFAULT_OPTIONS
+    DEFAULT_OPTIONS = Rack::Session::Abstract::Persisted::DEFAULT_OPTIONS
 
     def initialize(session = {})
       super(nil, nil)
@@ -328,6 +178,10 @@ module ActionController
       clear
     end
 
+    def fetch(key, *args, &block)
+      @data.fetch(key.to_s, *args, &block)
+    end
+
     private
 
       def load!
@@ -354,7 +208,7 @@ module ActionController
   #   class BooksControllerTest < ActionController::TestCase
   #     def test_create
   #       # Simulate a POST response with the given HTTP parameters.
-  #       post(:create, book: { title: "Love Hina" })
+  #       post(:create, params: { book: { title: "Love Hina" }})
   #
   #       # Assert that the controller tried to redirect us to
   #       # the created book's URI.
@@ -384,7 +238,7 @@ module ActionController
   #      request. You can modify this object before sending the HTTP request. For example,
   #      you might want to set some session properties before sending a GET request.
   # <b>@response</b>::
-  #      An ActionController::TestResponse object, representing the response
+  #      An ActionDispatch::TestResponse object, representing the response
   #      of the last HTTP response. In the above example, <tt>@response</tt> becomes valid
   #      after calling +post+. If the various assert methods are not sufficient, then you
   #      may use this object to inspect the HTTP response in detail.
@@ -407,21 +261,15 @@ module ActionController
   # In addition to these specific assertions, you also have easy access to various collections that the regular test/unit assertions
   # can be used against. These collections are:
   #
-  # * assigns: Instance variables assigned in the action that are available for the view.
   # * session: Objects being saved in the session.
   # * flash: The flash objects currently in the session.
   # * cookies: \Cookies being sent to the user on this request.
   #
   # These collections can be used just like any other hash:
   #
-  #   assert_not_nil assigns(:person) # makes sure that a @person instance variable was set
   #   assert_equal "Dave", cookies[:name] # makes sure that a cookie called :name was set as "Dave"
   #   assert flash.empty? # makes sure that there's nothing in the flash
   #
-  # For historic reasons, the assigns hash uses string-based keys. So <tt>assigns[:person]</tt> won't work, but <tt>assigns["person"]</tt> will. To
-  # appease our yearning for symbols, though, an alternative accessor has been devised using a method call instead of index referencing.
-  # So <tt>assigns(:person)</tt> will work just like <tt>assigns["person"]</tt>, but again, <tt>assigns[:person]</tt> will not work.
-  #
   # On top of the collections, you have the complete url that a given action redirected to available in <tt>redirect_to_url</tt>.
   #
   # For redirects within the same controller, you can even call follow_redirect and the redirect will be followed, triggering another
@@ -494,112 +342,136 @@ module ActionController
       # Simulate a GET request with the given parameters.
       #
       # - +action+: The controller action to call.
-      # - +parameters+: The HTTP parameters that you want to pass. This may
-      #   be +nil+, a hash, or a string that is appropriately encoded
+      # - +params+: The hash with HTTP parameters that you want to pass. This may be +nil+.
+      # - +body+: The request body with a string that is appropriately encoded
       #   (<tt>application/x-www-form-urlencoded</tt> or <tt>multipart/form-data</tt>).
       # - +session+: A hash of parameters to store in the session. This may be +nil+.
       # - +flash+: A hash of parameters to store in the flash. This may be +nil+.
       #
       # You can also simulate POST, PATCH, PUT, DELETE, and HEAD requests with
       # +post+, +patch+, +put+, +delete+, and +head+.
+      # Example sending parameters, session and setting a flash message:
+      #
+      #   get :show,
+      #     params: { id: 7 },
+      #     session: { user_id: 1 },
+      #     flash: { notice: 'This is flash message' }
       #
       # Note that the request method is not verified. The different methods are
       # available to make the tests more expressive.
       def get(action, *args)
-        process(action, "GET", *args)
+        res = process_with_kwargs("GET", action, *args)
+        cookies.update res.cookies
+        res
       end
 
       # Simulate a POST request with the given parameters and set/volley the response.
       # See +get+ for more details.
       def post(action, *args)
-        process(action, "POST", *args)
+        process_with_kwargs("POST", action, *args)
       end
 
       # Simulate a PATCH request with the given parameters and set/volley the response.
       # See +get+ for more details.
       def patch(action, *args)
-        process(action, "PATCH", *args)
+        process_with_kwargs("PATCH", action, *args)
       end
 
       # Simulate a PUT request with the given parameters and set/volley the response.
       # See +get+ for more details.
       def put(action, *args)
-        process(action, "PUT", *args)
+        process_with_kwargs("PUT", action, *args)
       end
 
       # Simulate a DELETE request with the given parameters and set/volley the response.
       # See +get+ for more details.
       def delete(action, *args)
-        process(action, "DELETE", *args)
+        process_with_kwargs("DELETE", action, *args)
       end
 
       # Simulate a HEAD request with the given parameters and set/volley the response.
       # See +get+ for more details.
       def head(action, *args)
-        process(action, "HEAD", *args)
+        process_with_kwargs("HEAD", action, *args)
       end
 
-      def xml_http_request(request_method, action, parameters = nil, session = nil, flash = nil)
+      def xml_http_request(*args)
+        ActiveSupport::Deprecation.warn(<<-MSG.strip_heredoc)
+          xhr and xml_http_request methods are deprecated in favor of
+          `get :index, xhr: true` and `post :create, xhr: true`
+        MSG
+
         @request.env['HTTP_X_REQUESTED_WITH'] = 'XMLHttpRequest'
-        @request.env['HTTP_ACCEPT'] ||=  [Mime::JS, Mime::HTML, Mime::XML, 'text/xml', Mime::ALL].join(', ')
-        __send__(request_method, action, parameters, session, flash).tap do
+        @request.env['HTTP_ACCEPT'] ||= [Mime[:js], Mime[:html], Mime[:xml], 'text/xml', '*/*'].join(', ')
+        __send__(*args).tap do
           @request.env.delete 'HTTP_X_REQUESTED_WITH'
           @request.env.delete 'HTTP_ACCEPT'
         end
       end
       alias xhr :xml_http_request
 
-      def paramify_values(hash_or_array_or_value)
-        case hash_or_array_or_value
-        when Hash
-          Hash[hash_or_array_or_value.map{|key, value| [key, paramify_values(value)] }]
-        when Array
-          hash_or_array_or_value.map {|i| paramify_values(i)}
-        when Rack::Test::UploadedFile, ActionDispatch::Http::UploadedFile
-          hash_or_array_or_value
-        else
-          hash_or_array_or_value.to_param
-        end
-      end
-
       # Simulate a HTTP request to +action+ by specifying request method,
       # parameters and set/volley the response.
       #
       # - +action+: The controller action to call.
-      # - +http_method+: Request method used to send the http request. Possible values
-      #   are +GET+, +POST+, +PATCH+, +PUT+, +DELETE+, +HEAD+. Defaults to +GET+.
-      # - +parameters+: The HTTP parameters. This may be +nil+, a hash, or a
-      #   string that is appropriately encoded (+application/x-www-form-urlencoded+
-      #   or +multipart/form-data+).
+      # - +method+: Request method used to send the HTTP request. Possible values
+      #   are +GET+, +POST+, +PATCH+, +PUT+, +DELETE+, +HEAD+. Defaults to +GET+. Can be a symbol.
+      # - +params+: The hash with HTTP parameters that you want to pass. This may be +nil+.
+      # - +body+: The request body with a string that is appropriately encoded
+      #   (<tt>application/x-www-form-urlencoded</tt> or <tt>multipart/form-data</tt>).
       # - +session+: A hash of parameters to store in the session. This may be +nil+.
       # - +flash+: A hash of parameters to store in the flash. This may be +nil+.
+      # - +format+: Request format. Defaults to +nil+. Can be string or symbol.
       #
       # Example calling +create+ action and sending two params:
       #
-      #   process :create, 'POST', user: { name: 'Gaurish Sharma', email: 'user@example.com' }
-      #
-      # Example sending parameters, +nil+ session and setting a flash message:
-      #
-      #   process :view, 'GET', { id: 7 }, nil, { notice: 'This is flash message' }
+      #   process :create,
+      #     method: 'POST',
+      #     params: {
+      #       user: { name: 'Gaurish Sharma', email: 'user@example.com' }
+      #     },
+      #     session: { user_id: 1 },
+      #     flash: { notice: 'This is flash message' }
       #
       # To simulate +GET+, +POST+, +PATCH+, +PUT+, +DELETE+ and +HEAD+ requests
       # prefer using #get, #post, #patch, #put, #delete and #head methods
       # respectively which will make tests more expressive.
       #
       # Note that the request method is not verified.
-      def process(action, http_method = 'GET', *args)
+      def process(action, *args)
         check_required_ivars
 
-        if args.first.is_a?(String) && http_method != 'HEAD'
-          @request.env['RAW_POST_DATA'] = args.shift
+        if kwarg_request?(args)
+          parameters, session, body, flash, http_method, format, xhr = args[0].values_at(:params, :session, :body, :flash, :method, :format, :xhr)
+        else
+          http_method, parameters, session, flash = args
+          format = nil
+
+          if parameters.is_a?(String) && http_method != 'HEAD'
+            body = parameters
+            parameters = nil
+          end
+
+          if parameters.present? || session.present? || flash.present?
+            non_kwarg_request_warning
+          end
+        end
+
+        if body.present?
+          @request.set_header 'RAW_POST_DATA', body
+        end
+
+        if http_method.present?
+          http_method = http_method.to_s.upcase
+        else
+          http_method = "GET"
         end
 
-        parameters, session, flash = args
         parameters ||= {}
 
-        # Ensure that numbers and symbols passed as params are converted to
-        # proper params, as is the case when engaging rack.
-        parameters = paramify_values(parameters) if html_format?(parameters)
+        if format.present?
+          parameters[:format] = format
+        end
 
         @html_document = nil
 
@@ -607,55 +479,91 @@ module ActionController
           @controller.extend(Testing::Functional)
         end
 
-        @request.recycle!
-        @response.recycle!
+        self.cookies.update @request.cookies
+        self.cookies.update_cookies_from_jar
+        @request.set_header 'HTTP_COOKIE', cookies.to_header
+        @request.delete_header 'action_dispatch.cookies'
+
+        @request          = TestRequest.new scrub_env!(@request.env), @request.session
+        @response         = build_response @response_klass
+        @response.request = @request
         @controller.recycle!
 
-        @request.env['REQUEST_METHOD'] = http_method
+        @request.set_header 'REQUEST_METHOD', http_method
+
+        parameters = parameters.symbolize_keys
 
-        controller_class_name = @controller.class.anonymous? ?
-          "anonymous" :
-          @controller.class.controller_path
+        generated_extras = @routes.generate_extras(parameters.merge(controller: controller_class_name, action: action.to_s))
+        generated_path = generated_path(generated_extras)
+        query_string_keys = query_parameter_names(generated_extras)
 
-        @request.assign_parameters(@routes, controller_class_name, action.to_s, parameters)
+        @request.assign_parameters(@routes, controller_class_name, action.to_s, parameters, generated_path, query_string_keys)
 
         @request.session.update(session) if session
         @request.flash.update(flash || {})
 
+        if xhr
+          @request.set_header 'HTTP_X_REQUESTED_WITH', 'XMLHttpRequest'
+          @request.fetch_header('HTTP_ACCEPT') do |k|
+            @request.set_header k, [Mime[:js], Mime[:html], Mime[:xml], 'text/xml', '*/*'].join(', ')
+          end
+        end
+
         @controller.request  = @request
         @controller.response = @response
 
-        build_request_uri(action, parameters)
-
-        name = @request.parameters[:action]
+        @request.fetch_header("SCRIPT_NAME") do |k|
+          @request.set_header k, @controller.config.relative_url_root
+        end
 
         @controller.recycle!
-        @controller.process(name)
+        @controller.process(action)
 
-        if cookies = @request.env['action_dispatch.cookies']
-          unless @response.committed?
-            cookies.write(@response)
+        @request.delete_header 'HTTP_COOKIE'
+
+        if @request.have_cookie_jar?
+          unless @request.cookie_jar.committed?
+            @request.cookie_jar.write(@response)
+            self.cookies.update(@request.cookie_jar.instance_variable_get(:@cookies))
           end
         end
         @response.prepare!
 
-        @assigns = @controller.respond_to?(:view_assigns) ? @controller.view_assigns : {}
-
         if flash_value = @request.flash.to_session_value
           @request.session['flash'] = flash_value
+        else
+          @request.session.delete('flash')
+        end
+
+        if xhr
+          @request.delete_header 'HTTP_X_REQUESTED_WITH'
+          @request.delete_header 'HTTP_ACCEPT'
         end
+        @request.query_string = ''
 
         @response
       end
 
+      def controller_class_name
+        @controller.class.anonymous? ? "anonymous" : @controller.class.controller_path
+      end
+
+      def generated_path(generated_extras)
+        generated_extras[0]
+      end
+
+      def query_parameter_names(generated_extras)
+        generated_extras[1] + [:controller, :action]
+      end
+
       def setup_controller_request_and_response
         @controller = nil unless defined? @controller
 
-        response_klass = TestResponse
+        @response_klass = ActionDispatch::TestResponse
 
         if klass = self.class.controller_class
           if klass < ActionController::Live
-            response_klass = LiveTestResponse
+            @response_klass = LiveTestResponse
           end
           unless @controller
             begin
@@ -666,8 +574,8 @@ module ActionController
           end
         end
 
-        @request          = build_request
-        @response         = build_response response_klass
+        @request          = TestRequest.create
+        @response         = build_response @response_klass
         @response.request = @request
 
         if @controller
@@ -676,12 +584,8 @@ module ActionController
         end
       end
 
-      def build_request
-        TestRequest.new
-      end
-
       def build_response(klass)
-        klass.new
+        klass.create
       end
 
       included do
@@ -693,6 +597,46 @@ module ActionController
 
       private
 
+      def scrub_env!(env)
+        env.delete_if { |k, v| k =~ /^(action_dispatch|rack)\.request/ }
+        env.delete_if { |k, v| k =~ /^action_dispatch\.rescue/ }
+        env.delete 'action_dispatch.request.query_parameters'
+        env.delete 'action_dispatch.request.request_parameters'
+        env
+      end
+
+      def process_with_kwargs(http_method, action, *args)
+        if kwarg_request?(args)
+          args.first.merge!(method: http_method)
+          process(action, *args)
+        else
+          non_kwarg_request_warning if args.any?
+
+          args = args.unshift(http_method)
+          process(action, *args)
+        end
+      end
+
+      REQUEST_KWARGS = %i(params session flash method body xhr)
+      def kwarg_request?(args)
+        args[0].respond_to?(:keys) && (
+          (args[0].key?(:format) && args[0].keys.size == 1) ||
+          args[0].keys.any? { |k| REQUEST_KWARGS.include?(k) }
+        )
+      end
+
+      def non_kwarg_request_warning
+        ActiveSupport::Deprecation.warn(<<-MSG.strip_heredoc)
+          ActionController::TestCase HTTP request methods will accept only
+          keyword arguments in future Rails versions.
+
+          Examples:
+
+          get :show, params: { id: 1 }, session: { user_id: 1 }
+          process :update, method: :post, params: { id: 1 }
+        MSG
+      end
+
       def document_root_element
         html_document.root
       end
@@ -707,22 +651,6 @@ module ActionController
         end
       end
 
-      def build_request_uri(action, parameters)
-        unless @request.env["PATH_INFO"]
-          options = @controller.respond_to?(:url_options) ? @controller.__send__(:url_options).merge(parameters) : parameters
-          options.update(
-            :action => action,
-            :relative_url_root => nil,
-            :_recall => @request.path_parameters)
-
-          url, query_string = @routes.path_for(options).split("?", 2)
-
-          @request.env["SCRIPT_NAME"] = @controller.config.relative_url_root
-          @request.env["PATH_INFO"] = url
-          @request.env["QUERY_STRING"] = query_string || ""
-        end
-      end
-
       def html_format?(parameters)
         return true unless parameters.key?(:format)
         Mime.fetch(parameters[:format]) { Mime['html'] }.html?
diff --git a/actionpack/lib/action_dispatch.rb b/actionpack/lib/action_dispatch.rb
index dcd3ee0644..f6336c8c7a 100644
--- a/actionpack/lib/action_dispatch.rb
+++ b/actionpack/lib/action_dispatch.rb
@@ -52,6 +52,7 @@ module ActionDispatch
     autoload :DebugExceptions
     autoload :ExceptionWrapper
     autoload :Flash
+    autoload :LoadInterlock
     autoload :ParamsParser
     autoload :PublicExceptions
     autoload :Reloader
diff --git a/actionpack/lib/action_dispatch/http/cache.rb b/actionpack/lib/action_dispatch/http/cache.rb
index 747d295261..30ade14c26 100644
--- a/actionpack/lib/action_dispatch/http/cache.rb
+++ b/actionpack/lib/action_dispatch/http/cache.rb
@@ -1,4 +1,3 @@
-
 module ActionDispatch
   module Http
     module Cache
@@ -8,13 +7,13 @@ module ActionDispatch
         HTTP_IF_NONE_MATCH     = 'HTTP_IF_NONE_MATCH'.freeze
 
         def if_modified_since
-          if since = env[HTTP_IF_MODIFIED_SINCE]
+          if since = get_header(HTTP_IF_MODIFIED_SINCE)
             Time.rfc2822(since) rescue nil
           end
         end
 
         def if_none_match
-          env[HTTP_IF_NONE_MATCH]
+          get_header HTTP_IF_NONE_MATCH
         end
 
         def if_none_match_etags
@@ -51,52 +50,51 @@ module ActionDispatch
       end
 
       module Response
-        attr_reader :cache_control, :etag
-        alias :etag? :etag
+        attr_reader :cache_control
 
         def last_modified
-          if last = headers[LAST_MODIFIED]
+          if last = get_header(LAST_MODIFIED)
             Time.httpdate(last)
           end
         end
 
         def last_modified?
-          headers.include?(LAST_MODIFIED)
+          has_header? LAST_MODIFIED
         end
 
         def last_modified=(utc_time)
-          headers[LAST_MODIFIED] = utc_time.httpdate
+          set_header LAST_MODIFIED, utc_time.httpdate
         end
 
         def date
-          if date_header = headers[DATE]
+          if date_header = get_header(DATE)
             Time.httpdate(date_header)
           end
         end
 
         def date?
-          headers.include?(DATE)
+          has_header? DATE
         end
 
         def date=(utc_time)
-          headers[DATE] = utc_time.httpdate
+          set_header DATE, utc_time.httpdate
         end
 
         def etag=(etag)
           key = ActiveSupport::Cache.expand_cache_key(etag)
-          @etag = self[ETAG] = %("#{Digest::MD5.hexdigest(key)}")
+          super %("#{Digest::MD5.hexdigest(key)}")
         end
 
+        def etag?; etag; end
+
       private
 
         DATE          = 'Date'.freeze
         LAST_MODIFIED = "Last-Modified".freeze
-        ETAG          = "ETag".freeze
-        CACHE_CONTROL = "Cache-Control".freeze
         SPECIAL_KEYS  = Set.new(%w[extras no-cache max-age public must-revalidate])
 
         def cache_control_segments
-          if cache_control = self[CACHE_CONTROL]
+          if cache_control = _cache_control
             cache_control.delete(' ').split(',')
           else
             []
@@ -123,12 +121,11 @@ module ActionDispatch
 
         def prepare_cache_control!
           @cache_control = cache_control_headers
-          @etag = self[ETAG]
         end
 
         def handle_conditional_get!
           if etag? || last_modified? || !@cache_control.empty?
-            set_conditional_cache_control!
+            set_conditional_cache_control!(@cache_control)
           end
         end
 
@@ -138,24 +135,24 @@ module ActionDispatch
         PRIVATE               = "private".freeze
         MUST_REVALIDATE       = "must-revalidate".freeze
 
-        def set_conditional_cache_control!
+        def set_conditional_cache_control!(cache_control)
           control = {}
           cc_headers = cache_control_headers
           if extras = cc_headers.delete(:extras)
-            @cache_control[:extras] ||= []
-            @cache_control[:extras] += extras
-            @cache_control[:extras].uniq!
+            cache_control[:extras] ||= []
+            cache_control[:extras] += extras
+            cache_control[:extras].uniq!
           end
 
           control.merge! cc_headers
-          control.merge! @cache_control
+          control.merge! cache_control
 
           if control.empty?
-            headers[CACHE_CONTROL] = DEFAULT_CACHE_CONTROL
+            self._cache_control = DEFAULT_CACHE_CONTROL
           elsif control[:no_cache]
-            headers[CACHE_CONTROL] = NO_CACHE
+            self._cache_control = NO_CACHE
             if control[:extras]
-              headers[CACHE_CONTROL] += ", #{control[:extras].join(', ')}"
+              self._cache_control = _cache_control + ", #{control[:extras].join(', ')}"
             end
           else
             extras  = control[:extras]
@@ -167,7 +164,7 @@ module ActionDispatch
             options << MUST_REVALIDATE if control[:must_revalidate]
             options.concat(extras) if extras
 
-            headers[CACHE_CONTROL] = options.join(", ")
+            self._cache_control = options.join(", ")
           end
         end
       end
diff --git a/actionpack/lib/action_dispatch/http/filter_parameters.rb b/actionpack/lib/action_dispatch/http/filter_parameters.rb
index 2b851cc28d..9dcab79c3a 100644
--- a/actionpack/lib/action_dispatch/http/filter_parameters.rb
+++ b/actionpack/lib/action_dispatch/http/filter_parameters.rb
@@ -1,5 +1,3 @@
-require 'active_support/core_ext/hash/keys'
-require 'active_support/core_ext/object/duplicable'
 require 'action_dispatch/http/parameter_filter'
 
 module ActionDispatch
@@ -16,7 +14,7 @@ module ActionDispatch
     #   env["action_dispatch.parameter_filter"] = [:foo, "bar"]
     #   => replaces the value to all keys matching /foo|bar/i with "[FILTERED]"
     #
-    #   env["action_dispatch.parameter_filter"] = lambda do |k,v|
+    #   env["action_dispatch.parameter_filter"] = -> (k, v) do
     #     v.reverse! if k =~ /secret/i
     #   end
     #   => reverses the value to all keys matching /secret/i
@@ -25,19 +23,19 @@ module ActionDispatch
       NULL_PARAM_FILTER = ParameterFilter.new # :nodoc:
       NULL_ENV_FILTER   = ParameterFilter.new ENV_MATCH # :nodoc:
 
-      def initialize(env)
+      def initialize
         super
         @filtered_parameters = nil
         @filtered_env        = nil
         @filtered_path       = nil
       end
 
-      # Return a hash of parameters with all sensitive data replaced.
+      # Returns a hash of parameters with all sensitive data replaced.
       def filtered_parameters
         @filtered_parameters ||= parameter_filter.filter(parameters)
       end
 
-      # Return a hash of request.env with all sensitive data replaced.
+      # Returns a hash of request.env with all sensitive data replaced.
       def filtered_env
         @filtered_env ||= env_filter.filter(@env)
       end
@@ -50,13 +48,13 @@ module ActionDispatch
     protected
 
       def parameter_filter
-        parameter_filter_for @env.fetch("action_dispatch.parameter_filter") {
+        parameter_filter_for fetch_header("action_dispatch.parameter_filter") {
           return NULL_PARAM_FILTER
         }
       end
 
       def env_filter
-        user_key = @env.fetch("action_dispatch.parameter_filter") {
+        user_key = fetch_header("action_dispatch.parameter_filter") {
           return NULL_ENV_FILTER
         }
         parameter_filter_for(Array(user_key) + ENV_MATCH)
diff --git a/actionpack/lib/action_dispatch/http/filter_redirect.rb b/actionpack/lib/action_dispatch/http/filter_redirect.rb
index cd603649c3..f4b806b8b5 100644
--- a/actionpack/lib/action_dispatch/http/filter_redirect.rb
+++ b/actionpack/lib/action_dispatch/http/filter_redirect.rb
@@ -4,9 +4,8 @@ module ActionDispatch
 
       FILTERED = '[FILTERED]'.freeze # :nodoc:
 
-      def filtered_location
-        filters = location_filter
-        if !filters.empty? && location_filter_match?(filters)
+      def filtered_location # :nodoc:
+        if location_filter_match?
           FILTERED
         else
           location
@@ -15,20 +14,20 @@ module ActionDispatch
 
     private
 
-      def location_filter
+      def location_filters
         if request
-          request.env['action_dispatch.redirect_filter'] || []
+          request.get_header('action_dispatch.redirect_filter') || []
         else
           []
         end
       end
 
-      def location_filter_match?(filters)
-        filters.any? do |filter|
+      def location_filter_match?
+        location_filters.any? do |filter|
           if String === filter
             location.include?(filter)
           elsif Regexp === filter
-            location.match(filter)
+            location =~ filter
           end
         end
       end
diff --git a/actionpack/lib/action_dispatch/http/headers.rb b/actionpack/lib/action_dispatch/http/headers.rb
index bc5410dc38..12f81dc1a5 100644
--- a/actionpack/lib/action_dispatch/http/headers.rb
+++ b/actionpack/lib/action_dispatch/http/headers.rb
@@ -30,27 +30,37 @@ module ActionDispatch
       HTTP_HEADER = /\A[A-Za-z0-9-]+\z/
 
       include Enumerable
-      attr_reader :env
 
-      def initialize(env = {}) # :nodoc:
-        @env = env
+      def self.from_hash(hash)
+        new ActionDispatch::Request.new hash
+      end
+
+      def initialize(request) # :nodoc:
+        @req = request
       end
 
       # Returns the value for the given key mapped to @env.
       def [](key)
-        @env[env_name(key)]
+        @req.get_header env_name(key)
       end
 
       # Sets the given value for the key mapped to @env.
       def []=(key, value)
-        @env[env_name(key)] = value
+        @req.set_header env_name(key), value
+      end
+
+      # Add a value to a multivalued header like Vary or Accept-Encoding.
+      def add(key, value)
+        @req.add_header env_name(key), value
       end
 
       def key?(key)
-        @env.key? env_name(key)
+        @req.has_header? env_name(key)
       end
       alias :include? :key?
 
+      DEFAULT = Object.new # :nodoc:
+
       # Returns the value for the given key mapped to @env.
       #
       # If the key is not found and an optional code block is not provided,
@@ -58,18 +68,22 @@ module ActionDispatch
       #
       # If the code block is provided, then it will be run and
       # its result returned.
-      def fetch(key, *args, &block)
-        @env.fetch env_name(key), *args, &block
+      def fetch(key, default = DEFAULT)
+        @req.fetch_header(env_name(key)) do
+          return default unless default == DEFAULT
+          return yield if block_given?
+          raise NameError, key
+        end
       end
 
       def each(&block)
-        @env.each(&block)
+        @req.each_header(&block)
       end
 
       # Returns a new Http::Headers instance containing the contents of
       # <tt>headers_or_env</tt> and the original instance.
       def merge(headers_or_env)
-        headers = Http::Headers.new(env.dup)
+        headers = @req.dup.headers
         headers.merge!(headers_or_env)
         headers
       end
@@ -79,11 +93,14 @@ module ActionDispatch
       # <tt>headers_or_env</tt>.
       def merge!(headers_or_env)
         headers_or_env.each do |key, value|
-          self[env_name(key)] = value
+          @req.set_header env_name(key), value
         end
       end
 
+      def env; @req.env.dup; end
+
       private
+
       # Converts a HTTP header name to an environment variable name if it is
       # not contained within the headers hash.
       def env_name(key)
diff --git a/actionpack/lib/action_dispatch/http/mime_negotiation.rb b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
index 53a98c5d0a..7acf91902d 100644
--- a/actionpack/lib/action_dispatch/http/mime_negotiation.rb
+++ b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
@@ -10,19 +10,18 @@ module ActionDispatch
         self.ignore_accept_header = false
       end
 
-      attr_reader :variant
-
-      # The MIME type of the HTTP request, such as Mime::XML.
+      # The MIME type of the HTTP request, such as Mime[:xml].
       #
       # For backward compatibility, the post \format is extracted from the
       # X-Post-Data-Format HTTP header if present.
       def content_mime_type
-        @env["action_dispatch.request.content_type"] ||= begin
-          if @env['CONTENT_TYPE'] =~ /^([^,\;]*)/
+        fetch_header("action_dispatch.request.content_type") do |k|
+          v = if get_header('CONTENT_TYPE') =~ /^([^,\;]*)/
             Mime::Type.lookup($1.strip.downcase)
           else
             nil
           end
+          set_header k, v
         end
       end
 
@@ -30,63 +29,73 @@ module ActionDispatch
         content_mime_type && content_mime_type.to_s
       end
 
+      def has_content_type?
+        has_header? 'CONTENT_TYPE'
+      end
+
       # Returns the accepted MIME type for the request.
       def accepts
-        @env["action_dispatch.request.accepts"] ||= begin
-          header = @env['HTTP_ACCEPT'].to_s.strip
+        fetch_header("action_dispatch.request.accepts") do |k|
+          header = get_header('HTTP_ACCEPT').to_s.strip
 
-          if header.empty?
+          v = if header.empty?
             [content_mime_type]
           else
             Mime::Type.parse(header)
           end
+          set_header k, v
         end
       end
 
       # Returns the MIME type for the \format used in the request.
       #
-      #   GET /posts/5.xml   | request.format => Mime::XML
-      #   GET /posts/5.xhtml | request.format => Mime::HTML
-      #   GET /posts/5       | request.format => Mime::HTML or MIME::JS, or request.accepts.first
+      #   GET /posts/5.xml   | request.format => Mime[:xml]
+      #   GET /posts/5.xhtml | request.format => Mime[:html]
+      #   GET /posts/5       | request.format => Mime[:html] or Mime[:js], or request.accepts.first
       #
       def format(view_path = [])
         formats.first || Mime::NullType.instance
       end
 
       def formats
-        @env["action_dispatch.request.formats"] ||= begin
+        fetch_header("action_dispatch.request.formats") do |k|
           params_readable = begin
                               parameters[:format]
                             rescue ActionController::BadRequest
                               false
                             end
 
-          if params_readable
+          v = if params_readable
             Array(Mime[parameters[:format]])
           elsif use_accept_header && valid_accept_header
             accepts
           elsif xhr?
-            [Mime::JS]
+            [Mime[:js]]
           else
-            [Mime::HTML]
+            [Mime[:html]]
           end
+          set_header k, v
         end
       end
 
       # Sets the \variant for template.
       def variant=(variant)
-        if variant.is_a?(Symbol)
-          @variant = [variant]
-        elsif variant.nil? || variant.is_a?(Array) && variant.any? && variant.all?{ |v| v.is_a?(Symbol) }
-          @variant = variant
+        variant = Array(variant)
+
+        if variant.all? { |v| v.is_a?(Symbol) }
+          @variant = ActiveSupport::ArrayInquirer.new(variant)
         else
-          raise ArgumentError, "request.variant must be set to a Symbol or an Array of Symbols, not a #{variant.class}. " \
+          raise ArgumentError, "request.variant must be set to a Symbol or an Array of Symbols. " \
             "For security reasons, never directly set the variant to a user-provided value, " \
             "like params[:variant].to_sym. Check user-provided value against a whitelist first, " \
             "then set the variant: request.variant = :tablet if params[:variant] == 'tablet'"
         end
       end
 
+      def variant
+        @variant ||= ActiveSupport::ArrayInquirer.new
+      end
+
       # Sets the \format by string extension, which can be used to force custom formats
       # that are not controlled by the extension.
       #
@@ -100,7 +109,7 @@ module ActionDispatch
       #   end
       def format=(extension)
         parameters[:format] = extension.to_s
-        @env["action_dispatch.request.formats"] = [Mime::Type.lookup_by_extension(parameters[:format])]
+        set_header "action_dispatch.request.formats", [Mime::Type.lookup_by_extension(parameters[:format])]
       end
 
       # Sets the \formats by string extensions. This differs from #format= by allowing you
@@ -119,9 +128,9 @@ module ActionDispatch
       #   end
       def formats=(extensions)
         parameters[:format] = extensions.first.to_s
-        @env["action_dispatch.request.formats"] = extensions.collect do |extension|
+        set_header "action_dispatch.request.formats", extensions.collect { |extension|
           Mime::Type.lookup_by_extension(extension)
-        end
+        }
       end
 
       # Receives an array of mimes and return the first user sent mime that
diff --git a/actionpack/lib/action_dispatch/http/mime_type.rb b/actionpack/lib/action_dispatch/http/mime_type.rb
index 047a17937a..b64f660ec5 100644
--- a/actionpack/lib/action_dispatch/http/mime_type.rb
+++ b/actionpack/lib/action_dispatch/http/mime_type.rb
@@ -1,23 +1,31 @@
-require 'set'
 require 'singleton'
 require 'active_support/core_ext/module/attribute_accessors'
 require 'active_support/core_ext/string/starts_ends_with'
 
 module Mime
-  class Mimes < Array
-    def symbols
-      @symbols ||= map(&:to_sym)
+  class Mimes
+    include Enumerable
+
+    def initialize
+      @mimes = []
+      @symbols = nil
     end
 
-    %w(<< concat shift unshift push pop []= clear compact! collect!
-    delete delete_at delete_if flatten! map! insert reject! reverse!
-    replace slice! sort! uniq!).each do |method|
-      module_eval <<-CODE, __FILE__, __LINE__ + 1
-        def #{method}(*)
-          @symbols = nil
-          super
-        end
-      CODE
+    def each
+      @mimes.each { |x| yield x }
+    end
+
+    def <<(type)
+      @mimes << type
+      @symbols = nil
+    end
+
+    def delete_if
+      @mimes.delete_if { |x| yield x }.tap { @symbols = nil }
+    end
+
+    def symbols
+      @symbols ||= map(&:to_sym)
     end
   end
 
@@ -35,6 +43,42 @@ module Mime
       return type if type.is_a?(Type)
       EXTENSION_LOOKUP.fetch(type.to_s) { |k| yield k }
     end
+
+    def const_missing(sym)
+      ext = sym.downcase
+      if Mime[ext]
+        ActiveSupport::Deprecation.warn <<-eow
+Accessing mime types via constants is deprecated.  Please change:
+
+  `Mime::#{sym}`
+
+to:
+
+  `Mime[:#{ext}]`
+        eow
+        Mime[ext]
+      else
+        super
+      end
+    end
+
+    def const_defined?(sym, inherit = true)
+      ext = sym.downcase
+      if Mime[ext]
+        ActiveSupport::Deprecation.warn <<-eow
+Accessing mime types via constants is deprecated.  Please change:
+
+  `Mime.const_defined?(#{sym})`
+
+to:
+
+  `Mime[:#{ext}]`
+        eow
+        true
+      else
+        super
+      end
+    end
   end
 
   # Encapsulates the notion of a mime type. Can be used at render time, for example, with:
@@ -45,15 +89,12 @@ module Mime
   #
   #       respond_to do |format|
   #         format.html
-  #         format.ics { render text: @post.to_ics, mime_type: Mime::Type["text/calendar"]  }
+  #         format.ics { render body: @post.to_ics, mime_type: Mime::Type.lookup("text/calendar")  }
   #         format.xml { render xml: @post }
   #       end
   #     end
   #   end
   class Type
-    @@html_types = Set.new [:html, :all]
-    cattr_reader :html_types
-
     attr_reader :symbol
 
     @register_callbacks = []
@@ -66,7 +107,7 @@ module Mime
       def initialize(index, name, q = nil)
         @index = index
         @name = name
-        q ||= 0.0 if @name == Mime::ALL.to_s # default wildcard match to end of list
+        q ||= 0.0 if @name == '*/*'.freeze # default wildcard match to end of list
         @q = ((q || 1.0).to_f * 100).to_i
       end
 
@@ -91,7 +132,7 @@ module Mime
           exchange_xml_items if app_xml_idx > text_xml_idx  # make sure app_xml is ahead of text_xml in the list
           delete_at(text_xml_idx)                 # delete text_xml from the list
         elsif text_xml_idx
-          text_xml.name = Mime::XML.to_s
+          text_xml.name = Mime[:xml].to_s
         end
 
         # Look for more specific XML-based types and sort them ahead of app/xml
@@ -120,7 +161,7 @@ module Mime
         end
 
         def app_xml_idx
-          @app_xml_idx ||= index(Mime::XML.to_s)
+          @app_xml_idx ||= index(Mime[:xml].to_s)
         end
 
         def text_xml
@@ -160,17 +201,17 @@ module Mime
       end
 
       def register(string, symbol, mime_type_synonyms = [], extension_synonyms = [], skip_lookup = false)
-        Mime.const_set(symbol.upcase, Type.new(string, symbol, mime_type_synonyms))
+        new_mime = Type.new(string, symbol, mime_type_synonyms)
 
-        new_mime = Mime.const_get(symbol.upcase)
         SET << new_mime
 
-        ([string] + mime_type_synonyms).each { |str| LOOKUP[str] = SET.last } unless skip_lookup
-        ([symbol] + extension_synonyms).each { |ext| EXTENSION_LOOKUP[ext.to_s] = SET.last }
+        ([string] + mime_type_synonyms).each { |str| LOOKUP[str] = new_mime } unless skip_lookup
+        ([symbol] + extension_synonyms).each { |ext| EXTENSION_LOOKUP[ext.to_s] = new_mime }
 
         @register_callbacks.each do |callback|
           callback.call(new_mime)
         end
+        new_mime
       end
 
       def parse(accept_header)
@@ -200,28 +241,27 @@ module Mime
         parse_data_with_trailing_star($1) if accept_header =~ TRAILING_STAR_REGEXP
       end
 
-      # For an input of <tt>'text'</tt>, returns <tt>[Mime::JSON, Mime::XML, Mime::ICS,
-      # Mime::HTML, Mime::CSS, Mime::CSV, Mime::JS, Mime::YAML, Mime::TEXT]</tt>.
+      # For an input of <tt>'text'</tt>, returns <tt>[Mime[:json], Mime[:xml], Mime[:ics],
+      # Mime[:html], Mime[:css], Mime[:csv], Mime[:js], Mime[:yaml], Mime[:text]</tt>.
       #
-      # For an input of <tt>'application'</tt>, returns <tt>[Mime::HTML, Mime::JS,
-      # Mime::XML, Mime::YAML, Mime::ATOM, Mime::JSON, Mime::RSS, Mime::URL_ENCODED_FORM]</tt>.
-      def parse_data_with_trailing_star(input)
-        Mime::SET.select { |m| m =~ input }
+      # For an input of <tt>'application'</tt>, returns <tt>[Mime[:html], Mime[:js],
+      # Mime[:xml], Mime[:yaml], Mime[:atom], Mime[:json], Mime[:rss], Mime[:url_encoded_form]</tt>.
+      def parse_data_with_trailing_star(type)
+        Mime::SET.select { |m| m =~ type }
       end
 
       # This method is opposite of register method.
       #
-      # Usage:
+      # To unregister a MIME type:
       #
       #   Mime::Type.unregister(:mobile)
       def unregister(symbol)
-        symbol = symbol.upcase
-        mime = Mime.const_get(symbol)
-        Mime.instance_eval { remove_const(symbol) }
-
-        SET.delete_if { |v| v.eql?(mime) }
-        LOOKUP.delete_if { |_,v| v.eql?(mime) }
-        EXTENSION_LOOKUP.delete_if { |_,v| v.eql?(mime) }
+        symbol = symbol.downcase
+        if mime = Mime[symbol]
+          SET.delete_if { |v| v.eql?(mime) }
+          LOOKUP.delete_if { |_, v| v.eql?(mime) }
+          EXTENSION_LOOKUP.delete_if { |_, v| v.eql?(mime) }
+        end
       end
     end
 
@@ -243,7 +283,7 @@ module Mime
     end
 
     def ref
-      to_sym || to_s
+      symbol || to_s
     end
 
     def ===(list)
@@ -255,24 +295,23 @@ module Mime
     end
 
     def ==(mime_type)
-      return false if mime_type.blank?
+      return false unless mime_type
       (@synonyms + [ self ]).any? do |synonym|
         synonym.to_s == mime_type.to_s || synonym.to_sym == mime_type.to_sym
       end
     end
 
     def =~(mime_type)
-      return false if mime_type.blank?
+      return false unless mime_type
       regexp = Regexp.new(Regexp.quote(mime_type.to_s))
-      (@synonyms + [ self ]).any? do |synonym|
-        synonym.to_s =~ regexp
-      end
+      @synonyms.any? { |synonym| synonym.to_s =~ regexp } || @string =~ regexp
     end
 
     def html?
-      @@html_types.include?(to_sym) || @string =~ /html/
+      symbol == :html || @string =~ /html/
     end
 
+    def all?; false; end
 
     private
 
@@ -292,6 +331,22 @@ module Mime
     end
   end
 
+  class AllType < Type
+    include Singleton
+
+    def initialize
+      super '*/*', :all
+    end
+
+    def all?; true; end
+    def html?; true; end
+  end
+
+  # ALL isn't a real MIME type, so we don't register it for lookup with the
+  # other concrete types. It's a wildcard match that we use for `respond_to`
+  # negotiation internals.
+  ALL = AllType.instance
+
   class NullType
     include Singleton
 
diff --git a/actionpack/lib/action_dispatch/http/mime_types.rb b/actionpack/lib/action_dispatch/http/mime_types.rb
index 0e4da36038..87715205d9 100644
--- a/actionpack/lib/action_dispatch/http/mime_types.rb
+++ b/actionpack/lib/action_dispatch/http/mime_types.rb
@@ -27,10 +27,7 @@ Mime::Type.register "application/x-www-form-urlencoded", :url_encoded_form
 
 # http://www.ietf.org/rfc/rfc4627.txt
 # http://www.json.org/JSONRequest.html
-Mime::Type.register "application/json", :json, %w( text/x-json application/jsonrequest )
+Mime::Type.register "application/json", :json, %w( text/x-json application/jsonrequest application/vnd.api+json )
 
 Mime::Type.register "application/pdf", :pdf, [], %w(pdf)
 Mime::Type.register "application/zip", :zip, [], %w(zip)
-
-# Create Mime::ALL but do not add it to the SET.
-Mime::ALL = Mime::Type.new("*/*", :all, [])
diff --git a/actionpack/lib/action_dispatch/http/parameter_filter.rb b/actionpack/lib/action_dispatch/http/parameter_filter.rb
index df4b073a17..e826551f4b 100644
--- a/actionpack/lib/action_dispatch/http/parameter_filter.rb
+++ b/actionpack/lib/action_dispatch/http/parameter_filter.rb
@@ -30,36 +30,46 @@ module ActionDispatch
             when Regexp
               regexps << item
             else
-              strings << item.to_s
+              strings << Regexp.escape(item.to_s)
             end
           end
 
-          regexps << Regexp.new(strings.join('|'), true) unless strings.empty?
-          new regexps, blocks
+          deep_regexps, regexps = regexps.partition { |r| r.to_s.include?("\\.".freeze) }
+          deep_strings, strings = strings.partition { |s| s.include?("\\.".freeze) }
+
+          regexps << Regexp.new(strings.join('|'.freeze), true) unless strings.empty?
+          deep_regexps << Regexp.new(deep_strings.join('|'.freeze), true) unless deep_strings.empty?
+
+          new regexps, deep_regexps, blocks
         end
 
-        attr_reader :regexps, :blocks
+        attr_reader :regexps, :deep_regexps, :blocks
 
-        def initialize(regexps, blocks)
+        def initialize(regexps, deep_regexps, blocks)
           @regexps = regexps
+          @deep_regexps = deep_regexps.any? ? deep_regexps : nil
           @blocks  = blocks
         end
 
-        def call(original_params)
+        def call(original_params, parents = [])
           filtered_params = {}
 
           original_params.each do |key, value|
+            parents.push(key) if deep_regexps
             if regexps.any? { |r| key =~ r }
               value = FILTERED
+            elsif deep_regexps && (joined = parents.join('.')) && deep_regexps.any? { |r| joined =~ r }
+              value = FILTERED
             elsif value.is_a?(Hash)
-              value = call(value)
+              value = call(value, parents)
             elsif value.is_a?(Array)
-              value = value.map { |v| v.is_a?(Hash) ? call(v) : v }
+              value = value.map { |v| v.is_a?(Hash) ? call(v, parents) : v }
             elsif blocks.any?
               key = key.dup if key.duplicable?
               value = value.dup if value.duplicable?
               blocks.each { |b| b.call(key, value) }
             end
+            parents.pop if deep_regexps
 
             filtered_params[key] = value
           end
diff --git a/actionpack/lib/action_dispatch/http/parameters.rb b/actionpack/lib/action_dispatch/http/parameters.rb
index c2f05ecc86..248ecfd676 100644
--- a/actionpack/lib/action_dispatch/http/parameters.rb
+++ b/actionpack/lib/action_dispatch/http/parameters.rb
@@ -1,27 +1,41 @@
-require 'active_support/core_ext/hash/keys'
-require 'active_support/core_ext/hash/indifferent_access'
-
 module ActionDispatch
   module Http
     module Parameters
       PARAMETERS_KEY = 'action_dispatch.request.path_parameters'
 
+      DEFAULT_PARSERS = {
+        Mime[:json] => lambda { |raw_post|
+          data = ActiveSupport::JSON.decode(raw_post)
+          data.is_a?(Hash) ? data : {:_json => data}
+        }
+      }
+
+      def self.included(klass)
+        class << klass
+          attr_accessor :parameter_parsers
+        end
+
+        klass.parameter_parsers = DEFAULT_PARSERS
+      end
       # Returns both GET and POST \parameters in a single hash.
       def parameters
-        @env["action_dispatch.request.parameters"] ||= begin
-          params = begin
-            request_parameters.merge(query_parameters)
-          rescue EOFError
-            query_parameters.dup
-          end
-          params.merge!(path_parameters)
-        end
+        params = get_header("action_dispatch.request.parameters")
+        return params if params
+
+        params = begin
+                   request_parameters.merge(query_parameters)
+                 rescue EOFError
+                   query_parameters.dup
+                 end
+        params.merge!(path_parameters)
+        set_header("action_dispatch.request.parameters", params)
+        params
       end
       alias :params :parameters
 
       def path_parameters=(parameters) #:nodoc:
-        @env.delete('action_dispatch.request.parameters')
-        @env[PARAMETERS_KEY] = parameters
+        delete_header('action_dispatch.request.parameters')
+        set_header PARAMETERS_KEY, parameters
       end
 
       # Returns a hash with the \parameters used to form the \path of the request.
@@ -29,31 +43,29 @@ module ActionDispatch
       #
       #   {'action' => 'my_action', 'controller' => 'my_controller'}
       def path_parameters
-        @env[PARAMETERS_KEY] ||= {}
+        get_header(PARAMETERS_KEY) || {}
       end
 
-    private
+      private
 
-      # Convert nested Hash to HashWithIndifferentAccess.
-      #
-      def normalize_encode_params(params)
-        case params
-        when Hash
-          if params.has_key?(:tempfile)
-            UploadedFile.new(params)
-          else
-            params.each_with_object({}) do |(key, val), new_hash|
-              new_hash[key] = if val.is_a?(Array)
-                val.map! { |el| normalize_encode_params(el) }
-              else
-                normalize_encode_params(val)
-              end
-            end.with_indifferent_access
-          end
-        else
-          params
+      def parse_formatted_parameters(parsers)
+        return yield if content_length.zero?
+
+        strategy = parsers.fetch(content_mime_type) { return yield }
+
+        begin
+          strategy.call(raw_post)
+        rescue => e # JSON or Ruby code block errors
+          my_logger = logger || ActiveSupport::Logger.new($stderr)
+          my_logger.debug "Error occurred while parsing request parameters.\nContents:\n\n#{raw_post}"
+
+          raise ParamsParser::ParseError.new(e.message, e)
         end
       end
+
+      def params_parsers
+        ActionDispatch::Request.parameter_parsers
+      end
     end
   end
 end
diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index cadbfc88cb..35e3ac304f 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -13,12 +13,14 @@ require 'action_dispatch/http/url'
 require 'active_support/core_ext/array/conversions'
 
 module ActionDispatch
-  class Request < Rack::Request
+  class Request
+    include Rack::Request::Helpers
     include ActionDispatch::Http::Cache::Request
     include ActionDispatch::Http::MimeNegotiation
     include ActionDispatch::Http::Parameters
     include ActionDispatch::Http::FilterParameters
     include ActionDispatch::Http::URL
+    include Rack::Request::Env
 
     autoload :Session, 'action_dispatch/request/session'
     autoload :Utils,   'action_dispatch/request/utils'
@@ -29,15 +31,20 @@ module ActionDispatch
         PATH_TRANSLATED REMOTE_HOST
         REMOTE_IDENT REMOTE_USER REMOTE_ADDR
         SERVER_NAME SERVER_PROTOCOL
+        ORIGINAL_SCRIPT_NAME
 
         HTTP_ACCEPT HTTP_ACCEPT_CHARSET HTTP_ACCEPT_ENCODING
         HTTP_ACCEPT_LANGUAGE HTTP_CACHE_CONTROL HTTP_FROM
-        HTTP_NEGOTIATE HTTP_PRAGMA ].freeze
+        HTTP_NEGOTIATE HTTP_PRAGMA HTTP_CLIENT_IP
+        HTTP_X_FORWARDED_FOR HTTP_VERSION
+        HTTP_X_REQUEST_ID HTTP_X_FORWARDED_HOST
+        SERVER_ADDR
+        ].freeze
 
     ENV_METHODS.each do |env|
       class_eval <<-METHOD, __FILE__, __LINE__ + 1
         def #{env.sub(/^HTTP_/n, '').downcase}  # def accept_charset
-          @env["#{env}"]                        #   @env["HTTP_ACCEPT_CHARSET"]
+          get_header "#{env}".freeze            #   get_header "HTTP_ACCEPT_CHARSET".freeze
         end                                     # end
       METHOD
     end
@@ -50,7 +57,6 @@ module ActionDispatch
       @original_fullpath = nil
       @fullpath          = nil
       @ip                = nil
-      @uuid              = nil
     end
 
     def check_path_parameters!
@@ -59,13 +65,32 @@ module ActionDispatch
       path_parameters.each do |key, value|
         next unless value.respond_to?(:valid_encoding?)
         unless value.valid_encoding?
-          raise ActionController::BadRequest, "Invalid parameter: #{key} => #{value}"
+          raise ActionController::BadRequest, "Invalid parameter encoding: #{key} => #{value.inspect}"
         end
       end
     end
 
+    PASS_NOT_FOUND = Class.new { # :nodoc:
+      def self.action(_); self; end
+      def self.call(_); [404, {'X-Cascade' => 'pass'}, []]; end
+    }
+
+    def controller_class
+      check_path_parameters!
+      params = path_parameters
+
+      if params.key?(:controller)
+        controller_param = params[:controller].underscore
+        params[:action] ||= 'index'
+        const_name = "#{controller_param.camelize}Controller"
+        ActiveSupport::Dependencies.constantize(const_name)
+      else
+        PASS_NOT_FOUND
+      end
+    end
+
     def key?(key)
-      @env.key?(key)
+      has_header? key
     end
 
     # List of HTTP request methods from the following RFCs:
@@ -102,27 +127,50 @@ module ActionDispatch
     # the application should use), this \method returns the overridden
     # value, not the original.
     def request_method
-      @request_method ||= check_method(env["REQUEST_METHOD"])
+      @request_method ||= check_method(super)
     end
 
     def routes # :nodoc:
-      env["action_dispatch.routes".freeze]
+      get_header("action_dispatch.routes".freeze)
     end
 
-    def original_script_name # :nodoc:
-      env['ORIGINAL_SCRIPT_NAME'.freeze]
+    def routes=(routes) # :nodoc:
+      set_header("action_dispatch.routes".freeze, routes)
     end
 
     def engine_script_name(_routes) # :nodoc:
-      env["ROUTES_#{_routes.object_id}_SCRIPT_NAME"]
+      get_header(_routes.env_key)
+    end
+
+    def engine_script_name=(name) # :nodoc:
+      set_header(routes.env_key, name.dup)
     end
 
     def request_method=(request_method) #:nodoc:
       if check_method(request_method)
-        @request_method = env["REQUEST_METHOD"] = request_method
+        @request_method = set_header("REQUEST_METHOD", request_method)
       end
     end
 
+    def controller_instance # :nodoc:
+      get_header('action_controller.instance'.freeze)
+    end
+
+    def controller_instance=(controller) # :nodoc:
+      set_header('action_controller.instance'.freeze, controller)
+    end
+
+    def http_auth_salt
+      get_header "action_dispatch.http_auth_salt"
+    end
+
+    def show_exceptions? # :nodoc:
+      # We're treating `nil` as "unset", and we want the default setting to be
+      # `true`.  This logic should be extracted to `env_config` and calculated
+      # once.
+      !(get_header('action_dispatch.show_exceptions'.freeze) == false)
+    end
+
     # Returns a symbol form of the #request_method
     def request_method_symbol
       HTTP_METHOD_LOOKUP[request_method]
@@ -132,7 +180,7 @@ module ActionDispatch
     # even if it was overridden by middleware. See #request_method for
     # more information.
     def method
-      @method ||= check_method(env["rack.methodoverride.original_method"] || env['REQUEST_METHOD'])
+      @method ||= check_method(get_header("rack.methodoverride.original_method") || get_header('REQUEST_METHOD'))
     end
 
     # Returns a symbol form of the #method
@@ -140,47 +188,11 @@ module ActionDispatch
       HTTP_METHOD_LOOKUP[method]
     end
 
-    # Is this a GET (or HEAD) request?
-    # Equivalent to <tt>request.request_method_symbol == :get</tt>.
-    def get?
-      HTTP_METHOD_LOOKUP[request_method] == :get
-    end
-
-    # Is this a POST request?
-    # Equivalent to <tt>request.request_method_symbol == :post</tt>.
-    def post?
-      HTTP_METHOD_LOOKUP[request_method] == :post
-    end
-
-    # Is this a PATCH request?
-    # Equivalent to <tt>request.request_method == :patch</tt>.
-    def patch?
-      HTTP_METHOD_LOOKUP[request_method] == :patch
-    end
-
-    # Is this a PUT request?
-    # Equivalent to <tt>request.request_method_symbol == :put</tt>.
-    def put?
-      HTTP_METHOD_LOOKUP[request_method] == :put
-    end
-
-    # Is this a DELETE request?
-    # Equivalent to <tt>request.request_method_symbol == :delete</tt>.
-    def delete?
-      HTTP_METHOD_LOOKUP[request_method] == :delete
-    end
-
-    # Is this a HEAD request?
-    # Equivalent to <tt>request.request_method_symbol == :head</tt>.
-    def head?
-      HTTP_METHOD_LOOKUP[request_method] == :head
-    end
-
     # Provides access to the request's HTTP headers, for example:
     #
     #   request.headers["Content-Type"] # => "text/plain"
     def headers
-      Http::Headers.new(@env)
+      @headers ||= Http::Headers.new(self)
     end
 
     # Returns a +String+ with the last requested path including their params.
@@ -191,7 +203,7 @@ module ActionDispatch
     #    # get '/foo?bar'
     #    request.original_fullpath # => '/foo?bar'
     def original_fullpath
-      @original_fullpath ||= (env["ORIGINAL_FULLPATH"] || fullpath)
+      @original_fullpath ||= (get_header("ORIGINAL_FULLPATH") || fullpath)
     end
 
     # Returns the +String+ full path including params of the last URL requested.
@@ -230,62 +242,78 @@ module ActionDispatch
     # (case-insensitive), which may need to be manually added depending on the
     # choice of JavaScript libraries and frameworks.
     def xml_http_request?
-      @env['HTTP_X_REQUESTED_WITH'] =~ /XMLHttpRequest/i
+      get_header('HTTP_X_REQUESTED_WITH') =~ /XMLHttpRequest/i
     end
     alias :xhr? :xml_http_request?
 
+    # Returns the IP address of client as a +String+.
     def ip
       @ip ||= super
     end
 
-    # Originating IP address, usually set by the RemoteIp middleware.
+    # Returns the IP address of client as a +String+,
+    # usually set by the RemoteIp middleware.
     def remote_ip
-      @remote_ip ||= (@env["action_dispatch.remote_ip"] || ip).to_s
+      @remote_ip ||= (get_header("action_dispatch.remote_ip") || ip).to_s
+    end
+
+    def remote_ip=(remote_ip)
+      set_header "action_dispatch.remote_ip".freeze, remote_ip
     end
 
+    ACTION_DISPATCH_REQUEST_ID = "action_dispatch.request_id".freeze # :nodoc:
+
     # Returns the unique request id, which is based on either the X-Request-Id header that can
     # be generated by a firewall, load balancer, or web server or by the RequestId middleware
     # (which sets the action_dispatch.request_id environment variable).
     #
     # This unique ID is useful for tracing a request from end-to-end as part of logging or debugging.
     # This relies on the rack variable set by the ActionDispatch::RequestId middleware.
-    def uuid
-      @uuid ||= env["action_dispatch.request_id"]
+    def request_id
+      get_header ACTION_DISPATCH_REQUEST_ID
+    end
+
+    def request_id=(id) # :nodoc:
+      set_header ACTION_DISPATCH_REQUEST_ID, id
     end
 
+    alias_method :uuid, :request_id
+
     # Returns the lowercase name of the HTTP server software.
     def server_software
-      (@env['SERVER_SOFTWARE'] && /^([a-zA-Z]+)/ =~ @env['SERVER_SOFTWARE']) ? $1.downcase : nil
+      (get_header('SERVER_SOFTWARE') && /^([a-zA-Z]+)/ =~ get_header('SERVER_SOFTWARE')) ? $1.downcase : nil
     end
 
     # Read the request \body. This is useful for web services that need to
     # work with raw requests directly.
     def raw_post
-      unless @env.include? 'RAW_POST_DATA'
+      unless has_header? 'RAW_POST_DATA'
         raw_post_body = body
-        @env['RAW_POST_DATA'] = raw_post_body.read(content_length)
+        set_header('RAW_POST_DATA', raw_post_body.read(content_length))
         raw_post_body.rewind if raw_post_body.respond_to?(:rewind)
       end
-      @env['RAW_POST_DATA']
+      get_header 'RAW_POST_DATA'
     end
 
     # The request body is an IO input stream. If the RAW_POST_DATA environment
     # variable is already set, wrap it in a StringIO.
     def body
-      if raw_post = @env['RAW_POST_DATA']
+      if raw_post = get_header('RAW_POST_DATA')
         raw_post.force_encoding(Encoding::BINARY)
         StringIO.new(raw_post)
       else
-        @env['rack.input']
+        body_stream
       end
     end
 
+    # Returns true if the request's content MIME type is
+    # +application/x-www-form-urlencoded+ or +multipart/form-data+.
     def form_data?
       FORM_DATA_MEDIA_TYPES.include?(content_mime_type.to_s)
     end
 
     def body_stream #:nodoc:
-      @env['rack.input']
+      get_header('rack.input')
     end
 
     # TODO This should be broken apart into AD::Request::Session and probably
@@ -296,51 +324,71 @@ module ActionDispatch
       else
         self.session = {}
       end
-      @env['action_dispatch.request.flash_hash'] = nil
+      self.flash = nil
     end
 
     def session=(session) #:nodoc:
-      Session.set @env, session
+      Session.set self, session
     end
 
     def session_options=(options)
-      Session::Options.set @env, options
+      Session::Options.set self, options
     end
 
     # Override Rack's GET method to support indifferent access
     def GET
-      @env["action_dispatch.request.query_parameters"] ||= Utils.deep_munge(normalize_encode_params(super || {}))
+      fetch_header("action_dispatch.request.query_parameters") do |k|
+        rack_query_params = super || {}
+        # Check for non UTF-8 parameter values, which would cause errors later
+        Request::Utils.check_param_encoding(rack_query_params)
+        set_header k, Request::Utils.normalize_encode_params(rack_query_params)
+      end
     rescue Rack::Utils::ParameterTypeError, Rack::Utils::InvalidParameterError => e
-      raise ActionController::BadRequest.new(:query, e)
+      raise ActionController::BadRequest.new("Invalid query parameters: #{e.message}", e)
     end
     alias :query_parameters :GET
 
     # Override Rack's POST method to support indifferent access
     def POST
-      @env["action_dispatch.request.request_parameters"] ||= Utils.deep_munge(normalize_encode_params(super || {}))
+      fetch_header("action_dispatch.request.request_parameters") do
+        pr = parse_formatted_parameters(params_parsers) do |params|
+          super || {}
+        end
+        self.request_parameters = Request::Utils.normalize_encode_params(pr)
+      end
+    rescue ParamsParser::ParseError # one of the parse strategies blew up
+      self.request_parameters = Request::Utils.normalize_encode_params(super || {})
+      raise
     rescue Rack::Utils::ParameterTypeError, Rack::Utils::InvalidParameterError => e
-      raise ActionController::BadRequest.new(:request, e)
+      raise ActionController::BadRequest.new("Invalid request parameters: #{e.message}", e)
     end
     alias :request_parameters :POST
 
     # Returns the authorization header regardless of whether it was specified directly or through one of the
     # proxy alternatives.
     def authorization
-      @env['HTTP_AUTHORIZATION']   ||
-      @env['X-HTTP_AUTHORIZATION'] ||
-      @env['X_HTTP_AUTHORIZATION'] ||
-      @env['REDIRECT_X_HTTP_AUTHORIZATION']
+      get_header('HTTP_AUTHORIZATION')   ||
+      get_header('X-HTTP_AUTHORIZATION') ||
+      get_header('X_HTTP_AUTHORIZATION') ||
+      get_header('REDIRECT_X_HTTP_AUTHORIZATION')
     end
 
-    # True if the request came from localhost, 127.0.0.1.
+    # True if the request came from localhost, 127.0.0.1, or ::1.
     def local?
       LOCALHOST =~ remote_addr && LOCALHOST =~ remote_ip
     end
 
-    protected
-      def parse_query(qs)
-        Utils.deep_munge(super)
-      end
+    def request_parameters=(params)
+      raise if params.nil?
+      set_header("action_dispatch.request.request_parameters".freeze, params)
+    end
+
+    def logger
+      get_header("action_dispatch.logger".freeze)
+    end
+
+    def commit_flash
+    end
 
     private
       def check_method(name)
diff --git a/actionpack/lib/action_dispatch/http/response.rb b/actionpack/lib/action_dispatch/http/response.rb
index 4061ea71a3..f0127aa276 100644
--- a/actionpack/lib/action_dispatch/http/response.rb
+++ b/actionpack/lib/action_dispatch/http/response.rb
@@ -32,46 +32,56 @@ module ActionDispatch # :nodoc:
   #    end
   #  end
   class Response
+    class Header < DelegateClass(Hash) # :nodoc:
+      def initialize(response, header)
+        @response = response
+        super(header)
+      end
+
+      def []=(k,v)
+        if @response.sending? || @response.sent?
+          raise ActionDispatch::IllegalStateError, 'header already sent'
+        end
+
+        super
+      end
+
+      def merge(other)
+        self.class.new @response, __getobj__.merge(other)
+      end
+
+      def to_hash
+        __getobj__.dup
+      end
+    end
+
     # The request that the response is responding to.
     attr_accessor :request
 
     # The HTTP status code.
     attr_reader :status
 
-    attr_writer :sending_file
-
-    # Get and set headers for this response.
-    attr_accessor :header
+    # Get headers for this response.
+    attr_reader :header
 
-    alias_method :headers=, :header=
     alias_method :headers,  :header
 
     delegate :[], :[]=, :to => :@header
     delegate :each, :to => :@stream
 
-    # Sets the HTTP response's content MIME type. For example, in the controller
-    # you could write this:
-    #
-    #  response.content_type = "text/plain"
-    #
-    # If a character set has been defined for this response (see charset=) then
-    # the character set information will also be included in the content type
-    # information.
-    attr_reader   :content_type
-
-    # The charset of the response. HTML wants to know the encoding of the
-    # content you're giving them, so we need to send that along.
-    attr_accessor :charset
-
     CONTENT_TYPE = "Content-Type".freeze
     SET_COOKIE   = "Set-Cookie".freeze
     LOCATION     = "Location".freeze
-    NO_CONTENT_CODES = [204, 304]
+    NO_CONTENT_CODES = [100, 101, 102, 204, 205, 304]
 
     cattr_accessor(:default_charset) { "utf-8" }
     cattr_accessor(:default_headers)
 
     include Rack::Response::Helpers
+    # Aliasing these off because AD::Http::Cache::Response defines them
+    alias :_cache_control :cache_control
+    alias :_cache_control= :cache_control=
+
     include ActionDispatch::Http::FilterRedirect
     include ActionDispatch::Http::Cache::Response
     include MonitorMixin
@@ -81,11 +91,21 @@ module ActionDispatch # :nodoc:
         @response = response
         @buf      = buf
         @closed   = false
+        @str_body = nil
+      end
+
+      def body
+        @str_body ||= begin
+                        buf = ''
+                        each { |chunk| buf << chunk }
+                        buf
+                      end
       end
 
       def write(string)
         raise IOError, "closed stream" if closed?
 
+        @str_body = nil
         @response.commit!
         @buf.push string
       end
@@ -110,36 +130,40 @@ module ActionDispatch # :nodoc:
       end
     end
 
+    def self.create(status = 200, header = {}, body = [], default_headers: self.default_headers)
+      header = merge_default_headers(header, default_headers)
+      new status, header, body
+    end
+
+    def self.merge_default_headers(original, default)
+      default.respond_to?(:merge) ? default.merge(original) : original
+    end
+
     # The underlying body, as a streamable object.
     attr_reader :stream
 
     def initialize(status = 200, header = {}, body = [])
       super()
 
-      header = merge_default_headers(header, self.class.default_headers)
+      @header = Header.new(self, header)
 
-      self.body, self.header, self.status = body, header, status
+      self.body, self.status = body, status
 
-      @sending_file = false
-      @blank        = false
       @cv           = new_cond
       @committed    = false
       @sending      = false
       @sent         = false
-      @content_type = nil
-      @charset      = nil
-
-      if content_type = self[CONTENT_TYPE]
-        type, charset = content_type.split(/;\s*charset=/)
-        @content_type = Mime::Type.lookup(type)
-        @charset = charset || self.class.default_charset
-      end
 
       prepare_cache_control!
 
       yield self if block_given?
     end
 
+    def has_header?(key);   headers.key? key;   end
+    def get_header(key);    headers[key];       end
+    def set_header(key, v); headers[key] = v;   end
+    def delete_header(key); headers.delete key; end
+
     def await_commit
       synchronize do
         @cv.wait_until { @committed }
@@ -184,7 +208,49 @@ module ActionDispatch # :nodoc:
 
     # Sets the HTTP content type.
     def content_type=(content_type)
-      @content_type = content_type.to_s
+      header_info = parse_content_type
+      set_content_type content_type.to_s, header_info.charset || self.class.default_charset
+    end
+
+    # Sets the HTTP response's content MIME type. For example, in the controller
+    # you could write this:
+    #
+    #  response.content_type = "text/plain"
+    #
+    # If a character set has been defined for this response (see charset=) then
+    # the character set information will also be included in the content type
+    # information.
+
+    def content_type
+      parse_content_type.mime_type
+    end
+
+    def sending_file=(v)
+      if true == v
+        self.charset = false
+      end
+    end
+
+    # Sets the HTTP character set. In case of nil parameter
+    # it sets the charset to utf-8.
+    #
+    #   response.charset = 'utf-16' # => 'utf-16'
+    #   response.charset = nil      # => 'utf-8'
+    def charset=(charset)
+      header_info = parse_content_type
+      if false == charset
+        set_header CONTENT_TYPE, header_info.mime_type
+      else
+        content_type = header_info.mime_type
+        set_content_type content_type, charset || self.class.default_charset
+      end
+    end
+
+    # The charset of the response. HTML wants to know the encoding of the
+    # content you're giving them, so we need to send that along.
+    def charset
+      header_info = parse_content_type
+      header_info.charset || self.class.default_charset
     end
 
     # The response code of the request.
@@ -213,17 +279,15 @@ module ActionDispatch # :nodoc:
     # Returns the content of the response as a string. This contains the contents
     # of any calls to <tt>render</tt>.
     def body
-      strings = []
-      each { |part| strings << part.to_s }
-      strings.join
+      @stream.body
     end
 
-    EMPTY = " "
+    def write(string)
+      @stream.write string
+    end
 
     # Allows you to manually set or override the response body.
     def body=(body)
-      @blank = true if body == EMPTY
-
       if body.respond_to?(:to_path)
         @stream = body
       else
@@ -233,31 +297,49 @@ module ActionDispatch # :nodoc:
       end
     end
 
-    def body_parts
-      parts = []
-      @stream.each { |x| parts << x }
-      parts
-    end
+    # Avoid having to pass an open file handle as the response body.
+    # Rack::Sendfile will usually intercept the response and uses
+    # the path directly, so there is no reason to open the file.
+    class FileBody #:nodoc:
+      attr_reader :to_path
 
-    def set_cookie(key, value)
-      ::Rack::Utils.set_cookie_header!(header, key, value)
+      def initialize(path)
+        @to_path = path
+      end
+
+      def body
+        File.binread(to_path)
+      end
+
+      # Stream the file's contents if Rack::Sendfile isn't present.
+      def each
+        File.open(to_path, 'rb') do |file|
+          while chunk = file.read(16384)
+            yield chunk
+          end
+        end
+      end
     end
 
-    def delete_cookie(key, value={})
-      ::Rack::Utils.delete_cookie_header!(header, key, value)
+    # Send the file stored at +path+ as the response body.
+    def send_file(path)
+      commit!
+      @stream = FileBody.new(path)
     end
 
-    # The location header we'll be responding with.
-    def location
-      headers[LOCATION]
+    def reset_body!
+      @stream = build_buffer(self, [])
     end
-    alias_method :redirect_url, :location
 
-    # Sets the location header we'll be responding with.
-    def location=(url)
-      headers[LOCATION] = url
+    def body_parts
+      parts = []
+      @stream.each { |x| parts << x }
+      parts
     end
 
+    # The location header we'll be responding with.
+    alias_method :redirect_url, :location
+
     def close
       stream.close if stream.respond_to?(:close)
     end
@@ -274,10 +356,11 @@ module ActionDispatch # :nodoc:
     end
 
     # Turns the Response into a Rack-compatible array of the status, headers,
-    # and body. Allows explict splatting:
+    # and body. Allows explicit splatting:
     #
     #   status, headers, body = *response
     def to_a
+      commit!
       rack_response @status, @header.to_hash
     end
     alias prepare! to_a
@@ -287,7 +370,7 @@ module ActionDispatch # :nodoc:
     #   assert_equal 'AuthorOfNewPage', r.cookies['author']
     def cookies
       cookies = {}
-      if header = self[SET_COOKIE]
+      if header = get_header(SET_COOKIE)
         header = header.split("\n") if header.respond_to?(:to_str)
         header.each do |cookie|
           if pair = cookie.split(';').first
@@ -301,16 +384,34 @@ module ActionDispatch # :nodoc:
 
   private
 
-    def before_committed
+    ContentTypeHeader = Struct.new :mime_type, :charset
+    NullContentTypeHeader = ContentTypeHeader.new nil, nil
+
+    def parse_content_type
+      content_type = get_header CONTENT_TYPE
+      if content_type
+        type, charset = content_type.split(/;\s*charset=/)
+        type = nil if type.empty?
+        ContentTypeHeader.new(type, charset)
+      else
+        NullContentTypeHeader
+      end
     end
 
-    def before_sending
+    def set_content_type(content_type, charset)
+      type = (content_type || '').dup
+      type << "; charset=#{charset}" if charset
+      set_header CONTENT_TYPE, type
     end
 
-    def merge_default_headers(original, default)
-      return original unless default.respond_to?(:merge)
+    def before_committed
+      return if committed?
+      assign_default_content_type_and_charset!
+      handle_conditional_get!
+      handle_no_content!
+    end
 
-      default.merge(original)
+    def before_sending
     end
 
     def build_buffer(response, body)
@@ -321,20 +422,12 @@ module ActionDispatch # :nodoc:
       body.respond_to?(:each) ? body : [body]
     end
 
-    def assign_default_content_type_and_charset!(headers)
-      return if headers[CONTENT_TYPE].present?
-
-      @content_type ||= Mime::HTML
-      @charset      ||= self.class.default_charset unless @charset == false
+    def assign_default_content_type_and_charset!
+      return if content_type
 
-      type = @content_type.to_s.dup
-      type << "; charset=#{@charset}" if append_charset?
-
-      headers[CONTENT_TYPE] = type
-    end
-
-    def append_charset?
-      !@sending_file && @charset != false
+      ct = parse_content_type
+      set_content_type(ct.mime_type || Mime[:html].to_s,
+                       ct.charset || self.class.default_charset)
     end
 
     class RackBody
@@ -373,14 +466,15 @@ module ActionDispatch # :nodoc:
       end
     end
 
-    def rack_response(status, header)
-      assign_default_content_type_and_charset!(header)
-      handle_conditional_get!
-
-      header[SET_COOKIE] = header[SET_COOKIE].join("\n") if header[SET_COOKIE].respond_to?(:join)
-
+    def handle_no_content!
       if NO_CONTENT_CODES.include?(@status)
-        header.delete CONTENT_TYPE
+        @header.delete CONTENT_TYPE
+        @header.delete 'Content-Length'
+      end
+    end
+
+    def rack_response(status, header)
+      if NO_CONTENT_CODES.include?(status)
         [status, header, []]
       else
         [status, header, RackBody.new(self)]
diff --git a/actionpack/lib/action_dispatch/http/upload.rb b/actionpack/lib/action_dispatch/http/upload.rb
index 540e11a4a0..a221f4c5af 100644
--- a/actionpack/lib/action_dispatch/http/upload.rb
+++ b/actionpack/lib/action_dispatch/http/upload.rb
@@ -28,7 +28,13 @@ module ActionDispatch
         raise(ArgumentError, ':tempfile is required') unless @tempfile
 
         @original_filename = hash[:filename]
-        @original_filename &&= @original_filename.encode "UTF-8"
+        if @original_filename
+          begin
+            @original_filename.encode!(Encoding::UTF_8)
+          rescue EncodingError
+            @original_filename.force_encoding(Encoding::UTF_8)
+          end
+        end
         @content_type      = hash[:type]
         @headers           = hash[:head]
       end
diff --git a/actionpack/lib/action_dispatch/http/url.rb b/actionpack/lib/action_dispatch/http/url.rb
index 001b14ec97..92b10b6d3b 100644
--- a/actionpack/lib/action_dispatch/http/url.rb
+++ b/actionpack/lib/action_dispatch/http/url.rb
@@ -1,11 +1,10 @@
 require 'active_support/core_ext/module/attribute_accessors'
-require 'active_support/core_ext/hash/slice'
 
 module ActionDispatch
   module Http
     module URL
       IP_HOST_REGEXP  = /\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/
-      HOST_REGEXP     = /(^[^:]+:\/\/)?([^:]+)(?::(\d+$))?/
+      HOST_REGEXP     = /(^[^:]+:\/\/)?(\[[^\]]+\]|[^:]+)(?::(\d+$))?/
       PROTOCOL_REGEXP = /^([^:]+)(:)?(\/\/)?$/
 
       mattr_accessor :tld_length
@@ -67,7 +66,7 @@ module ActionDispatch
         end
 
         def path_for(options)
-          path  = options[:script_name].to_s.chomp("/")
+          path  = options[:script_name].to_s.chomp("/".freeze)
           path << options[:path] if options.key?(:path)
 
           add_trailing_slash(path) if options[:trailing_slash]
@@ -184,7 +183,7 @@ module ActionDispatch
         end
       end
 
-      def initialize(env)
+      def initialize
         super
         @protocol = nil
         @port     = nil
@@ -229,10 +228,10 @@ module ActionDispatch
       #   req = Request.new 'HTTP_HOST' => 'example.com:8080'
       #   req.raw_host_with_port # => "example.com:8080"
       def raw_host_with_port
-        if forwarded = env["HTTP_X_FORWARDED_HOST"]
+        if forwarded = x_forwarded_host.presence
           forwarded.split(/,\s?/).last
         else
-          env['HTTP_HOST'] || "#{env['SERVER_NAME'] || env['SERVER_ADDR']}:#{env['SERVER_PORT']}"
+          get_header('HTTP_HOST') || "#{server_name || server_addr}:#{get_header('SERVER_PORT')}"
         end
       end
 
@@ -245,7 +244,7 @@ module ActionDispatch
       #   req = Request.new 'HTTP_HOST' => 'example.com:8080'
       #   req.host # => "example.com"
       def host
-        raw_host_with_port.sub(/:\d+$/, '')
+        raw_host_with_port.sub(/:\d+$/, ''.freeze)
       end
 
       # Returns a \host:\port string for this request, such as "example.com" or
@@ -348,7 +347,7 @@ module ActionDispatch
       end
 
       def server_port
-        @env['SERVER_PORT'].to_i
+        get_header('SERVER_PORT').to_i
       end
 
       # Returns the \domain part of a \host, such as "rubyonrails.org" in "www.rubyonrails.org". You can specify
diff --git a/actionpack/lib/action_dispatch/journey/formatter.rb b/actionpack/lib/action_dispatch/journey/formatter.rb
index 992c1a9efe..0323360faa 100644
--- a/actionpack/lib/action_dispatch/journey/formatter.rb
+++ b/actionpack/lib/action_dispatch/journey/formatter.rb
@@ -14,7 +14,7 @@ module ActionDispatch
 
       def generate(name, options, path_parameters, parameterize = nil)
         constraints = path_parameters.merge(options)
-        missing_keys = []
+        missing_keys = nil # need for variable scope
 
         match_route(name, constraints) do |route|
           parameterized_parts = extract_parameterized_parts(route, options, path_parameters, parameterize)
@@ -25,22 +25,22 @@ module ActionDispatch
           next unless name || route.dispatcher?
 
           missing_keys = missing_keys(route, parameterized_parts)
-          next unless missing_keys.empty?
+          next if missing_keys && !missing_keys.empty?
           params = options.dup.delete_if do |key, _|
             parameterized_parts.key?(key) || route.defaults.key?(key)
           end
 
           defaults       = route.defaults
           required_parts = route.required_parts
-          parameterized_parts.delete_if do |key, value|
-            value.to_s == defaults[key].to_s && !required_parts.include?(key)
+          parameterized_parts.keep_if do |key, value|
+            (defaults[key].nil? && value.present?) || value.to_s != defaults[key].to_s || required_parts.include?(key)
           end
 
           return [route.format(parameterized_parts), params]
         end
 
-        message = "No route matches #{Hash[constraints.sort].inspect}"
-        message << " missing required keys: #{missing_keys.sort.inspect}" unless missing_keys.empty?
+        message = "No route matches #{Hash[constraints.sort_by{|k,v| k.to_s}].inspect}"
+        message << " missing required keys: #{missing_keys.sort.inspect}" if missing_keys && !missing_keys.empty?
 
         raise ActionController::UrlGenerationError, message
       end
@@ -54,12 +54,12 @@ module ActionDispatch
         def extract_parameterized_parts(route, options, recall, parameterize = nil)
           parameterized_parts = recall.merge(options)
 
-          keys_to_keep = route.parts.reverse.drop_while { |part|
+          keys_to_keep = route.parts.reverse_each.drop_while { |part|
             !options.key?(part) || (options[part] || recall[part]).nil?
           } | route.required_parts
 
-          (parameterized_parts.keys - keys_to_keep).each do |bad_key|
-            parameterized_parts.delete(bad_key)
+          parameterized_parts.delete_if do |bad_key, _|
+            !keys_to_keep.include?(bad_key)
           end
 
           if parameterize
@@ -110,15 +110,36 @@ module ActionDispatch
           routes
         end
 
+        module RegexCaseComparator
+          DEFAULT_INPUT = /[-_.a-zA-Z0-9]+\/[-_.a-zA-Z0-9]+/
+          DEFAULT_REGEX = /\A#{DEFAULT_INPUT}\Z/
+
+          def self.===(regex)
+            DEFAULT_INPUT == regex
+          end
+        end
+
         # Returns an array populated with missing keys if any are present.
         def missing_keys(route, parts)
-          missing_keys = []
+          missing_keys = nil
           tests = route.path.requirements
           route.required_parts.each { |key|
-            if tests.key?(key)
-              missing_keys << key unless /\A#{tests[key]}\Z/ === parts[key]
+            case tests[key]
+            when nil
+              unless parts[key]
+                missing_keys ||= []
+                missing_keys << key
+              end
+            when RegexCaseComparator
+              unless RegexCaseComparator::DEFAULT_REGEX === parts[key]
+                missing_keys ||= []
+                missing_keys << key
+              end
             else
-              missing_keys << key unless parts[key]
+              unless /\A#{tests[key]}\Z/ === parts[key]
+                missing_keys ||= []
+                missing_keys << key
+              end
             end
           }
           missing_keys
@@ -134,7 +155,7 @@ module ActionDispatch
 
         def build_cache
           root = { ___routes: [] }
-          routes.each_with_index do |route, i|
+          routes.routes.each_with_index do |route, i|
             leaf = route.required_defaults.inject(root) do |h, tuple|
               h[tuple] ||= {}
             end
diff --git a/actionpack/lib/action_dispatch/journey/nfa/dot.rb b/actionpack/lib/action_dispatch/journey/nfa/dot.rb
index 47bf76bdbf..7063b44bb5 100644
--- a/actionpack/lib/action_dispatch/journey/nfa/dot.rb
+++ b/actionpack/lib/action_dispatch/journey/nfa/dot.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 module ActionDispatch
   module Journey # :nodoc:
     module NFA # :nodoc:
diff --git a/actionpack/lib/action_dispatch/journey/nodes/node.rb b/actionpack/lib/action_dispatch/journey/nodes/node.rb
index bb01c087bc..2793c5668d 100644
--- a/actionpack/lib/action_dispatch/journey/nodes/node.rb
+++ b/actionpack/lib/action_dispatch/journey/nodes/node.rb
@@ -14,15 +14,15 @@ module ActionDispatch
         end
 
         def each(&block)
-          Visitors::Each.new(block).accept(self)
+          Visitors::Each::INSTANCE.accept(self, block)
         end
 
         def to_s
-          Visitors::String.new.accept(self)
+          Visitors::String::INSTANCE.accept(self, '')
         end
 
         def to_dot
-          Visitors::Dot.new.accept(self)
+          Visitors::Dot::INSTANCE.accept(self)
         end
 
         def to_sym
@@ -30,7 +30,7 @@ module ActionDispatch
         end
 
         def name
-          left.tr '*:', ''
+          left.tr '*:'.freeze, ''.freeze
         end
 
         def type
@@ -39,10 +39,15 @@ module ActionDispatch
 
         def symbol?; false; end
         def literal?; false; end
+        def terminal?; false; end
+        def star?; false; end
+        def cat?; false; end
+        def group?; false; end
       end
 
       class Terminal < Node # :nodoc:
         alias :symbol :left
+        def terminal?; true; end
       end
 
       class Literal < Terminal # :nodoc:
@@ -69,11 +74,13 @@ module ActionDispatch
       class Symbol < Terminal # :nodoc:
         attr_accessor :regexp
         alias :symbol :regexp
+        attr_reader :name
 
         DEFAULT_EXP = /[^\.\/\?]+/
         def initialize(left)
           super
           @regexp = DEFAULT_EXP
+          @name = left.tr '*:'.freeze, ''.freeze
         end
 
         def default_regexp?
@@ -89,9 +96,11 @@ module ActionDispatch
 
       class Group < Unary # :nodoc:
         def type; :GROUP; end
+        def group?; true; end
       end
 
       class Star < Unary # :nodoc:
+        def star?; true; end
         def type; :STAR; end
 
         def name
@@ -111,6 +120,7 @@ module ActionDispatch
       end
 
       class Cat < Binary # :nodoc:
+        def cat?; true; end
         def type; :CAT; end
       end
 
diff --git a/actionpack/lib/action_dispatch/journey/parser_extras.rb b/actionpack/lib/action_dispatch/journey/parser_extras.rb
index 14892f4321..fff0299812 100644
--- a/actionpack/lib/action_dispatch/journey/parser_extras.rb
+++ b/actionpack/lib/action_dispatch/journey/parser_extras.rb
@@ -6,6 +6,10 @@ module ActionDispatch
     class Parser < Racc::Parser # :nodoc:
       include Journey::Nodes
 
+      def self.parse(string)
+        new.parse string
+      end
+
       def initialize
         @scanner = Scanner.new
       end
diff --git a/actionpack/lib/action_dispatch/journey/path/pattern.rb b/actionpack/lib/action_dispatch/journey/path/pattern.rb
index 64b48ca45f..5ee8810066 100644
--- a/actionpack/lib/action_dispatch/journey/path/pattern.rb
+++ b/actionpack/lib/action_dispatch/journey/path/pattern.rb
@@ -1,5 +1,3 @@
-require 'action_dispatch/journey/router/strexp'
-
 module ActionDispatch
   module Journey # :nodoc:
     module Path # :nodoc:
@@ -7,14 +5,20 @@ module ActionDispatch
         attr_reader :spec, :requirements, :anchored
 
         def self.from_string string
-          new Journey::Router::Strexp.build(string, {}, ["/.?"], true)
+          build(string, {}, "/.?", true)
+        end
+
+        def self.build(path, requirements, separators, anchored)
+          parser = Journey::Parser.new
+          ast = parser.parse path
+          new ast, requirements, separators, anchored
         end
 
-        def initialize(strexp)
-          @spec         = strexp.ast
-          @requirements = strexp.requirements
-          @separators   = strexp.separators.join
-          @anchored     = strexp.anchor
+        def initialize(ast, requirements, separators, anchored)
+          @spec         = ast
+          @requirements = requirements
+          @separators   = separators
+          @anchored     = anchored
 
           @names          = nil
           @optional_names = nil
@@ -28,12 +32,12 @@ module ActionDispatch
         end
 
         def ast
-          @spec.grep(Nodes::Symbol).each do |node|
+          @spec.find_all(&:symbol?).each do |node|
             re = @requirements[node.to_sym]
             node.regexp = re if re
           end
 
-          @spec.grep(Nodes::Star).each do |node|
+          @spec.find_all(&:star?).each do |node|
             node = node.left
             node.regexp = @requirements[node.to_sym] || /(.+)/
           end
@@ -42,7 +46,7 @@ module ActionDispatch
         end
 
         def names
-          @names ||= spec.grep(Nodes::Symbol).map(&:name)
+          @names ||= spec.find_all(&:symbol?).map(&:name)
         end
 
         def required_names
@@ -50,36 +54,11 @@ module ActionDispatch
         end
 
         def optional_names
-          @optional_names ||= spec.grep(Nodes::Group).flat_map { |group|
-            group.grep(Nodes::Symbol)
+          @optional_names ||= spec.find_all(&:group?).flat_map { |group|
+            group.find_all(&:symbol?)
           }.map(&:name).uniq
         end
 
-        class RegexpOffsets < Journey::Visitors::Visitor # :nodoc:
-          attr_reader :offsets
-
-          def initialize(matchers)
-            @matchers      = matchers
-            @capture_count = [0]
-          end
-
-          def visit(node)
-            super
-            @capture_count
-          end
-
-          def visit_SYMBOL(node)
-            node = node.to_sym
-
-            if @matchers.key?(node)
-              re = /#{@matchers[node]}|/
-              @capture_count.push((re.match('').length - 1) + (@capture_count.last || 0))
-            else
-              @capture_count << (@capture_count.last || 0)
-            end
-          end
-        end
-
         class AnchoredRegexp < Journey::Visitors::Visitor # :nodoc:
           def initialize(separator, matchers)
             @separator = separator
@@ -189,8 +168,20 @@ module ActionDispatch
           def offsets
             return @offsets if @offsets
 
-            viz = RegexpOffsets.new(@requirements)
-            @offsets = viz.accept(spec)
+            @offsets = [0]
+
+            spec.find_all(&:symbol?).each do |node|
+              node = node.to_sym
+
+              if @requirements.key?(node)
+                re = /#{@requirements[node]}|/
+                @offsets.push((re.match('').length - 1) + @offsets.last)
+              else
+                @offsets << @offsets.last
+              end
+            end
+
+            @offsets
           end
       end
     end
diff --git a/actionpack/lib/action_dispatch/journey/route.rb b/actionpack/lib/action_dispatch/journey/route.rb
index 4d5c18984a..35c2b1b86e 100644
--- a/actionpack/lib/action_dispatch/journey/route.rb
+++ b/actionpack/lib/action_dispatch/journey/route.rb
@@ -1,42 +1,88 @@
 module ActionDispatch
   module Journey # :nodoc:
     class Route # :nodoc:
-      attr_reader :app, :path, :defaults, :name
+      attr_reader :app, :path, :defaults, :name, :precedence
 
       attr_reader :constraints
       alias :conditions :constraints
 
-      attr_accessor :precedence
+      module VerbMatchers
+        VERBS = %w{ DELETE GET HEAD OPTIONS LINK PATCH POST PUT TRACE UNLINK }
+        VERBS.each do |v|
+          class_eval <<-eoc
+          class #{v}
+            def self.verb; name.split("::").last; end
+            def self.call(req); req.#{v.downcase}?; end
+          end
+          eoc
+        end
+
+        class Unknown
+          attr_reader :verb
+
+          def initialize(verb)
+            @verb = verb
+          end
+
+          def call(request); @verb === request.request_method; end
+        end
+
+        class All
+          def self.call(_); true; end
+          def self.verb; ''; end
+        end
+
+        VERB_TO_CLASS = VERBS.each_with_object({ :all => All }) do |verb, hash|
+          klass = const_get verb
+          hash[verb]                 = klass
+          hash[verb.downcase]        = klass
+          hash[verb.downcase.to_sym] = klass
+        end
+
+      end
+
+      def self.verb_matcher(verb)
+        VerbMatchers::VERB_TO_CLASS.fetch(verb) do
+          VerbMatchers::Unknown.new verb.to_s.dasherize.upcase
+        end
+      end
+
+      def self.build(name, app, path, constraints, required_defaults, defaults)
+        request_method_match = verb_matcher(constraints.delete(:request_method))
+        new name, app, path, constraints, required_defaults, defaults, request_method_match, 0
+      end
 
       ##
       # +path+ is a path constraint.
       # +constraints+ is a hash of constraints to be applied to this route.
-      def initialize(name, app, path, constraints, defaults = {})
+      def initialize(name, app, path, constraints, required_defaults, defaults, request_method_match, precedence)
         @name        = name
         @app         = app
         @path        = path
 
+        @request_method_match = request_method_match
         @constraints = constraints
         @defaults    = defaults
         @required_defaults = nil
+        @_required_defaults = required_defaults
         @required_parts    = nil
         @parts             = nil
         @decorated_ast     = nil
-        @precedence        = 0
+        @precedence        = precedence
         @path_formatter    = @path.build_formatter
       end
 
       def ast
         @decorated_ast ||= begin
           decorated_ast = path.ast
-          decorated_ast.grep(Nodes::Terminal).each { |n| n.memo = self }
+          decorated_ast.find_all(&:terminal?).each { |n| n.memo = self }
           decorated_ast
         end
       end
 
       def requirements # :nodoc:
         # needed for rails `rake routes`
-        path.requirements.merge(@defaults).delete_if { |_,v|
+        @defaults.merge(path.requirements).delete_if { |_,v|
           /.+?/ == v
         }
       end
@@ -73,7 +119,7 @@ module ActionDispatch
       end
 
       def required_default?(key)
-        (constraints[:required_defaults] || []).include?(key)
+        @_required_defaults.include?(key)
       end
 
       def required_defaults
@@ -91,9 +137,8 @@ module ActionDispatch
       end
 
       def matches?(request)
-        constraints.all? do |method, value|
-          next true unless request.respond_to?(method)
-
+        match_verb(request) &&
+        constraints.all? { |method, value|
           case value
           when Regexp, String
             value === request.send(method).to_s
@@ -106,15 +151,28 @@ module ActionDispatch
           else
             value === request.send(method)
           end
-        end
+        }
       end
 
       def ip
         constraints[:ip] || //
       end
 
+      def requires_matching_verb?
+        !@request_method_match.all? { |x| x == VerbMatchers::All }
+      end
+
       def verb
-        constraints[:request_method] || //
+        verbs.join('|')
+      end
+
+      private
+      def verbs
+        @request_method_match.map(&:verb)
+      end
+
+      def match_verb(request)
+        @request_method_match.any? { |m| m.call request }
       end
     end
   end
diff --git a/actionpack/lib/action_dispatch/journey/router.rb b/actionpack/lib/action_dispatch/journey/router.rb
index 2b036796ab..f649588520 100644
--- a/actionpack/lib/action_dispatch/journey/router.rb
+++ b/actionpack/lib/action_dispatch/journey/router.rb
@@ -1,5 +1,4 @@
 require 'action_dispatch/journey/router/utils'
-require 'action_dispatch/journey/router/strexp'
 require 'action_dispatch/journey/routes'
 require 'action_dispatch/journey/formatter'
 
@@ -88,7 +87,7 @@ module ActionDispatch
         end
 
         def custom_routes
-          partitioned_routes.last
+          routes.custom_routes
         end
 
         def filter_routes(path)
@@ -102,7 +101,7 @@ module ActionDispatch
           }
 
           routes =
-            if req.request_method == "HEAD"
+            if req.head?
               match_head_routes(routes, req)
             else
               match_routes(routes, req)
@@ -121,7 +120,8 @@ module ActionDispatch
         end
 
         def match_head_routes(routes, req)
-          head_routes = match_routes(routes, req)
+          verb_specific_routes = routes.select(&:requires_matching_verb?)
+          head_routes = match_routes(verb_specific_routes, req)
 
           if head_routes.empty?
             begin
diff --git a/actionpack/lib/action_dispatch/journey/router/strexp.rb b/actionpack/lib/action_dispatch/journey/router/strexp.rb
deleted file mode 100644
index 4b7738f335..0000000000
--- a/actionpack/lib/action_dispatch/journey/router/strexp.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-module ActionDispatch
-  module Journey # :nodoc:
-    class Router # :nodoc:
-      class Strexp # :nodoc:
-        class << self
-          alias :compile :new
-        end
-
-        attr_reader :path, :requirements, :separators, :anchor, :ast
-
-        def self.build(path, requirements, separators, anchor = true)
-          parser = Journey::Parser.new
-          ast = parser.parse path
-          new ast, path, requirements, separators, anchor
-        end
-
-        def initialize(ast, path, requirements, separators, anchor = true)
-          @ast          = ast
-          @path         = path
-          @requirements = requirements
-          @separators   = separators
-          @anchor       = anchor
-        end
-      end
-    end
-  end
-end
diff --git a/actionpack/lib/action_dispatch/journey/router/utils.rb b/actionpack/lib/action_dispatch/journey/router/utils.rb
index 2b0a6575d4..9793ca1c7a 100644
--- a/actionpack/lib/action_dispatch/journey/router/utils.rb
+++ b/actionpack/lib/action_dispatch/journey/router/utils.rb
@@ -14,10 +14,10 @@ module ActionDispatch
         #   normalize_path("/%ab")  # => "/%AB"
         def self.normalize_path(path)
           path = "/#{path}"
-          path.squeeze!('/')
-          path.sub!(%r{/+\Z}, '')
+          path.squeeze!('/'.freeze)
+          path.sub!(%r{/+\Z}, ''.freeze)
           path.gsub!(/(%[a-f0-9]{2})/) { $1.upcase }
-          path = '/' if path == ''
+          path = '/' if path == ''.freeze
           path
         end
 
@@ -55,7 +55,7 @@ module ActionDispatch
 
           def unescape_uri(uri)
             encoding = uri.encoding == US_ASCII ? UTF_8 : uri.encoding
-            uri.gsub(ESCAPED) { [$&[1, 2].hex].pack('C') }.force_encoding(encoding)
+            uri.gsub(ESCAPED) { |match| [match[1, 2].hex].pack('C') }.force_encoding(encoding)
           end
 
           protected
diff --git a/actionpack/lib/action_dispatch/journey/routes.rb b/actionpack/lib/action_dispatch/journey/routes.rb
index 80e3818ccd..f7b009109e 100644
--- a/actionpack/lib/action_dispatch/journey/routes.rb
+++ b/actionpack/lib/action_dispatch/journey/routes.rb
@@ -5,16 +5,20 @@ module ActionDispatch
     class Routes # :nodoc:
       include Enumerable
 
-      attr_reader :routes, :named_routes
+      attr_reader :routes, :custom_routes, :anchored_routes
 
       def initialize
         @routes             = []
-        @named_routes       = {}
         @ast                = nil
-        @partitioned_routes = nil
+        @anchored_routes    = []
+        @custom_routes      = []
         @simulator          = nil
       end
 
+      def empty?
+        routes.empty?
+      end
+
       def length
         routes.length
       end
@@ -30,18 +34,21 @@ module ActionDispatch
 
       def clear
         routes.clear
-        named_routes.clear
+        anchored_routes.clear
+        custom_routes.clear
       end
 
-      def partitioned_routes
-        @partitioned_routes ||= routes.partition do |r|
-          r.path.anchored && r.ast.grep(Nodes::Symbol).all?(&:default_regexp?)
+      def partition_route(route)
+        if route.path.anchored && route.ast.grep(Nodes::Symbol).all?(&:default_regexp?)
+          anchored_routes << route
+        else
+          custom_routes << route
         end
       end
 
       def ast
         @ast ||= begin
-          asts = partitioned_routes.first.map(&:ast)
+          asts = anchored_routes.map(&:ast)
           Nodes::Or.new(asts) unless asts.empty?
         end
       end
@@ -53,13 +60,10 @@ module ActionDispatch
         end
       end
 
-      # Add a route to the routing table.
-      def add_route(app, path, conditions, defaults, name = nil)
-        route = Route.new(name, app, path, conditions, defaults)
-
-        route.precedence = routes.length
+      def add_route(name, mapping)
+        route = mapping.make_route name, routes.length
         routes << route
-        named_routes[name] = route if name && !named_routes[name]
+        partition_route(route)
         clear_cache!
         route
       end
@@ -68,7 +72,6 @@ module ActionDispatch
 
         def clear_cache!
           @ast                = nil
-          @partitioned_routes = nil
           @simulator          = nil
         end
     end
diff --git a/actionpack/lib/action_dispatch/journey/visitors.rb b/actionpack/lib/action_dispatch/journey/visitors.rb
index 52b4c8b489..306d2e674a 100644
--- a/actionpack/lib/action_dispatch/journey/visitors.rb
+++ b/actionpack/lib/action_dispatch/journey/visitors.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 module ActionDispatch
   module Journey # :nodoc:
     class Format
@@ -92,6 +90,45 @@ module ActionDispatch
           end
       end
 
+      class FunctionalVisitor # :nodoc:
+        DISPATCH_CACHE = {}
+
+        def accept(node, seed)
+          visit(node, seed)
+        end
+
+        def visit node, seed
+          send(DISPATCH_CACHE[node.type], node, seed)
+        end
+
+        def binary(node, seed)
+          visit(node.right, visit(node.left, seed))
+        end
+        def visit_CAT(n, seed); binary(n, seed); end
+
+        def nary(node, seed)
+          node.children.inject(seed) { |s, c| visit(c, s) }
+        end
+        def visit_OR(n, seed); nary(n, seed); end
+
+        def unary(node, seed)
+          visit(node.left, seed)
+        end
+        def visit_GROUP(n, seed); unary(n, seed); end
+        def visit_STAR(n, seed); unary(n, seed); end
+
+        def terminal(node, seed);   seed; end
+        def visit_LITERAL(n, seed); terminal(n, seed); end
+        def visit_SYMBOL(n, seed);  terminal(n, seed); end
+        def visit_SLASH(n, seed);   terminal(n, seed); end
+        def visit_DOT(n, seed);     terminal(n, seed); end
+
+        instance_methods(false).each do |pim|
+          next unless pim =~ /^visit_(.*)$/
+          DISPATCH_CACHE[$1.to_sym] = pim
+        end
+      end
+
       class FormatBuilder < Visitor # :nodoc:
         def accept(node); Journey::Format.new(super); end
         def terminal(node); [node.left]; end
@@ -117,104 +154,110 @@ module ActionDispatch
       end
 
       # Loop through the requirements AST
-      class Each < Visitor # :nodoc:
-        attr_reader :block
-
-        def initialize(block)
-          @block = block
-        end
-
-        def visit(node)
+      class Each < FunctionalVisitor # :nodoc:
+        def visit(node, block)
           block.call(node)
           super
         end
+
+        INSTANCE = new
       end
 
-      class String < Visitor # :nodoc:
+      class String < FunctionalVisitor # :nodoc:
         private
 
-        def binary(node)
-          [visit(node.left), visit(node.right)].join
+        def binary(node, seed)
+          visit(node.right, visit(node.left, seed))
         end
 
-        def nary(node)
-          node.children.map { |c| visit(c) }.join '|'
+        def nary(node, seed)
+          last_child = node.children.last
+          node.children.inject(seed) { |s, c|
+            string = visit(c, s)
+            string << "|".freeze unless last_child == c
+            string
+          }
         end
 
-        def terminal(node)
-          node.left
+        def terminal(node, seed)
+          seed + node.left
         end
 
-        def visit_GROUP(node)
-          "(#{visit(node.left)})"
+        def visit_GROUP(node, seed)
+          visit(node.left, seed << "(".freeze) << ")".freeze
         end
+
+        INSTANCE = new
       end
 
-      class Dot < Visitor # :nodoc:
+      class Dot < FunctionalVisitor # :nodoc:
         def initialize
           @nodes = []
           @edges = []
         end
 
-        def accept(node)
+        def accept(node, seed = [[], []])
           super
+          nodes, edges = seed
           <<-eodot
   digraph parse_tree {
     size="8,5"
     node [shape = none];
     edge [dir = none];
-    #{@nodes.join "\n"}
-    #{@edges.join("\n")}
+    #{nodes.join "\n"}
+    #{edges.join("\n")}
   }
           eodot
         end
 
         private
 
-          def binary(node)
-            node.children.each do |c|
-              @edges << "#{node.object_id} -> #{c.object_id};"
-            end
+          def binary(node, seed)
+            seed.last.concat node.children.map { |c|
+              "#{node.object_id} -> #{c.object_id};"
+            }
             super
           end
 
-          def nary(node)
-            node.children.each do |c|
-              @edges << "#{node.object_id} -> #{c.object_id};"
-            end
+          def nary(node, seed)
+            seed.last.concat node.children.map { |c|
+              "#{node.object_id} -> #{c.object_id};"
+            }
             super
           end
 
-          def unary(node)
-            @edges << "#{node.object_id} -> #{node.left.object_id};"
+          def unary(node, seed)
+            seed.last << "#{node.object_id} -> #{node.left.object_id};"
             super
           end
 
-          def visit_GROUP(node)
-            @nodes << "#{node.object_id} [label=\"()\"];"
+          def visit_GROUP(node, seed)
+            seed.first << "#{node.object_id} [label=\"()\"];"
             super
           end
 
-          def visit_CAT(node)
-            @nodes << "#{node.object_id} [label=\"○\"];"
+          def visit_CAT(node, seed)
+            seed.first << "#{node.object_id} [label=\"○\"];"
             super
           end
 
-          def visit_STAR(node)
-            @nodes << "#{node.object_id} [label=\"*\"];"
+          def visit_STAR(node, seed)
+            seed.first << "#{node.object_id} [label=\"*\"];"
             super
           end
 
-          def visit_OR(node)
-            @nodes << "#{node.object_id} [label=\"|\"];"
+          def visit_OR(node, seed)
+            seed.first << "#{node.object_id} [label=\"|\"];"
             super
           end
 
-          def terminal(node)
+          def terminal(node, seed)
             value = node.left
 
-            @nodes << "#{node.object_id} [label=\"#{value}\"];"
+            seed.first << "#{node.object_id} [label=\"#{value}\"];"
+            seed
           end
+          INSTANCE = new
       end
     end
   end
diff --git a/actionpack/lib/action_dispatch/middleware/cookies.rb b/actionpack/lib/action_dispatch/middleware/cookies.rb
index b7687ca100..2889acaeb8 100644
--- a/actionpack/lib/action_dispatch/middleware/cookies.rb
+++ b/actionpack/lib/action_dispatch/middleware/cookies.rb
@@ -1,15 +1,57 @@
 require 'active_support/core_ext/hash/keys'
-require 'active_support/core_ext/module/attribute_accessors'
-require 'active_support/core_ext/object/blank'
 require 'active_support/key_generator'
 require 'active_support/message_verifier'
 require 'active_support/json'
 
 module ActionDispatch
-  class Request < Rack::Request
+  class Request
     def cookie_jar
-      env['action_dispatch.cookies'] ||= Cookies::CookieJar.build(self)
+      fetch_header('action_dispatch.cookies'.freeze) do
+        self.cookie_jar = Cookies::CookieJar.build(self, cookies)
+      end
+    end
+
+    # :stopdoc:
+    def have_cookie_jar?
+      has_header? 'action_dispatch.cookies'.freeze
+    end
+
+    def cookie_jar=(jar)
+      set_header 'action_dispatch.cookies'.freeze, jar
+    end
+
+    def key_generator
+      get_header Cookies::GENERATOR_KEY
+    end
+
+    def signed_cookie_salt
+      get_header Cookies::SIGNED_COOKIE_SALT
+    end
+
+    def encrypted_cookie_salt
+      get_header Cookies::ENCRYPTED_COOKIE_SALT
+    end
+
+    def encrypted_signed_cookie_salt
+      get_header Cookies::ENCRYPTED_SIGNED_COOKIE_SALT
+    end
+
+    def secret_token
+      get_header Cookies::SECRET_TOKEN
+    end
+
+    def secret_key_base
+      get_header Cookies::SECRET_KEY_BASE
+    end
+
+    def cookies_serializer
+      get_header Cookies::COOKIES_SERIALIZER
+    end
+
+    def cookies_digest
+      get_header Cookies::COOKIES_DIGEST
     end
+    # :startdoc:
   end
 
   # \Cookies are read and written through ActionController#cookies.
@@ -79,6 +121,9 @@ module ActionDispatch
   #     domain: %w(.example.com .example.org) # Allow the cookie
   #                                           # for concrete domain names.
   #
+  # * <tt>:tld_length</tt> - When using <tt>:domain => :all</tt>, this option can be used to explicitly
+  #   set the TLD length when using a short (<= 3 character) domain that is being interpreted as part of a TLD.
+  #   For example, to share cookies between user1.lvh.me and user2.lvh.me, set <tt>:tld_length</tt> to 1.
   # * <tt>:expires</tt> - The time at which this cookie expires, as a \Time object.
   # * <tt>:secure</tt> - Whether this cookie is only transmitted to HTTPS servers.
   #   Default is +false+.
@@ -115,7 +160,7 @@ module ActionDispatch
       #   cookies.permanent.signed[:remember_me] = current_user.id
       #   # => Set-Cookie: remember_me=BAhU--848956038e692d7046deab32b7131856ab20e14e; path=/; expires=Sun, 16-Dec-2029 03:24:16 GMT
       def permanent
-        @permanent ||= PermanentCookieJar.new(self, @key_generator, @options)
+        @permanent ||= PermanentCookieJar.new(self)
       end
 
       # Returns a jar that'll automatically generate a signed representation of cookie value and verify it when reading from
@@ -135,10 +180,10 @@ module ActionDispatch
       #   cookies.signed[:discount] # => 45
       def signed
         @signed ||=
-          if @options[:upgrade_legacy_signed_cookies]
-            UpgradeLegacySignedCookieJar.new(self, @key_generator, @options)
+          if upgrade_legacy_signed_cookies?
+            UpgradeLegacySignedCookieJar.new(self)
           else
-            SignedCookieJar.new(self, @key_generator, @options)
+            SignedCookieJar.new(self)
           end
       end
 
@@ -158,10 +203,10 @@ module ActionDispatch
       #   cookies.encrypted[:discount] # => 45
       def encrypted
         @encrypted ||=
-          if @options[:upgrade_legacy_signed_cookies]
-            UpgradeLegacyEncryptedCookieJar.new(self, @key_generator, @options)
+          if upgrade_legacy_signed_cookies?
+            UpgradeLegacyEncryptedCookieJar.new(self)
           else
-            EncryptedCookieJar.new(self, @key_generator, @options)
+            EncryptedCookieJar.new(self)
           end
       end
 
@@ -169,22 +214,28 @@ module ActionDispatch
       # Used by ActionDispatch::Session::CookieStore to avoid the need to introduce new cookie stores.
       def signed_or_encrypted
         @signed_or_encrypted ||=
-          if @options[:secret_key_base].present?
+          if request.secret_key_base.present?
             encrypted
           else
             signed
           end
       end
+
+      private
+
+      def upgrade_legacy_signed_cookies?
+        request.secret_token.present? && request.secret_key_base.present?
+      end
     end
 
     # Passing the ActiveSupport::MessageEncryptor::NullSerializer downstream
     # to the Message{Encryptor,Verifier} allows us to handle the
     # (de)serialization step within the cookie jar, which gives us the
     # opportunity to detect and migrate legacy cookies.
-    module VerifyAndUpgradeLegacySignedMessage
+    module VerifyAndUpgradeLegacySignedMessage # :nodoc:
       def initialize(*args)
         super
-        @legacy_verifier = ActiveSupport::MessageVerifier.new(@options[:secret_token], serializer: ActiveSupport::MessageEncryptor::NullSerializer)
+        @legacy_verifier = ActiveSupport::MessageVerifier.new(request.secret_token, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
       end
 
       def verify_and_upgrade_legacy_signed_message(name, signed_message)
@@ -194,6 +245,11 @@ module ActionDispatch
       rescue ActiveSupport::MessageVerifier::InvalidSignature
         nil
       end
+
+      private
+        def parse(name, signed_message)
+          super || verify_and_upgrade_legacy_signed_message(name, signed_message)
+        end
     end
 
     class CookieJar #:nodoc:
@@ -213,38 +269,18 @@ module ActionDispatch
       # $& => example.local
       DOMAIN_REGEXP = /[^.]*\.([^.]*|..\...|...\...)$/
 
-      def self.options_for_env(env) #:nodoc:
-        { signed_cookie_salt: env[SIGNED_COOKIE_SALT] || '',
-          encrypted_cookie_salt: env[ENCRYPTED_COOKIE_SALT] || '',
-          encrypted_signed_cookie_salt: env[ENCRYPTED_SIGNED_COOKIE_SALT] || '',
-          secret_token: env[SECRET_TOKEN],
-          secret_key_base: env[SECRET_KEY_BASE],
-          upgrade_legacy_signed_cookies: env[SECRET_TOKEN].present? && env[SECRET_KEY_BASE].present?,
-          serializer: env[COOKIES_SERIALIZER],
-          digest: env[COOKIES_DIGEST]
-        }
-      end
-
-      def self.build(request)
-        env = request.env
-        key_generator = env[GENERATOR_KEY]
-        options = options_for_env env
-
-        host = request.host
-        secure = request.ssl?
-
-        new(key_generator, host, secure, options).tap do |hash|
-          hash.update(request.cookies)
+      def self.build(req, cookies)
+        new(req).tap do |hash|
+          hash.update(cookies)
         end
       end
 
-      def initialize(key_generator, host = nil, secure = false, options = {})
-        @key_generator = key_generator
+      attr_reader :request
+
+      def initialize(request)
         @set_cookies = {}
         @delete_cookies = {}
-        @host = host
-        @secure = secure
-        @options = options
+        @request = request
         @cookies = {}
         @committed = false
       end
@@ -280,6 +316,17 @@ module ActionDispatch
         self
       end
 
+      def update_cookies_from_jar
+        request_jar = @request.cookie_jar.instance_variable_get(:@cookies)
+        set_cookies = request_jar.reject { |k,_| @delete_cookies.key?(k) }
+
+        @cookies.update set_cookies if set_cookies
+      end
+
+      def to_header
+        @cookies.map { |k,v| "#{k}=#{v}" }.join ';'
+      end
+
       def handle_options(options) #:nodoc:
         options[:path] ||= "/"
 
@@ -289,12 +336,12 @@ module ActionDispatch
 
           # if host is not ip and matches domain regexp
           # (ip confirms to domain regexp so we explicitly check for ip)
-          options[:domain] = if (@host !~ /^[\d.]+$/) && (@host =~ domain_regexp)
+          options[:domain] = if (request.host !~ /^[\d.]+$/) && (request.host =~ domain_regexp)
             ".#{$&}"
           end
         elsif options[:domain].is_a? Array
           # if host matches one of the supplied domains without a dot in front of it
-          options[:domain] = options[:domain].find {|domain| @host.include? domain.sub(/^\./, '') }
+          options[:domain] = options[:domain].find {|domain| request.host.include? domain.sub(/^\./, '') }
         end
       end
 
@@ -349,50 +396,74 @@ module ActionDispatch
       end
 
       def write(headers)
-        @set_cookies.each { |k, v| ::Rack::Utils.set_cookie_header!(headers, k, v) if write_cookie?(v) }
-        @delete_cookies.each { |k, v| ::Rack::Utils.delete_cookie_header!(headers, k, v) }
-      end
-
-      def recycle! #:nodoc:
-        @set_cookies = {}
-        @delete_cookies = {}
+        if header = make_set_cookie_header(headers[HTTP_HEADER])
+          headers[HTTP_HEADER] = header
+        end
       end
 
       mattr_accessor :always_write_cookie
       self.always_write_cookie = false
 
       private
-        def write_cookie?(cookie)
-          @secure || !cookie[:secure] || always_write_cookie
-        end
+
+      def make_set_cookie_header(header)
+        header = @set_cookies.inject(header) { |m, (k, v)|
+          if write_cookie?(v)
+            ::Rack::Utils.add_cookie_to_header(m, k, v)
+          else
+            m
+          end
+        }
+        @delete_cookies.inject(header) { |m, (k, v)|
+          ::Rack::Utils.add_remove_cookie_to_header(m, k, v)
+        }
+      end
+
+      def write_cookie?(cookie)
+        request.ssl? || !cookie[:secure] || always_write_cookie
+      end
     end
 
-    class PermanentCookieJar #:nodoc:
+    class AbstractCookieJar # :nodoc:
       include ChainedCookieJars
 
-      def initialize(parent_jar, key_generator, options = {})
+      def initialize(parent_jar)
         @parent_jar = parent_jar
-        @key_generator = key_generator
-        @options = options
       end
 
       def [](name)
-        @parent_jar[name.to_s]
+        if data = @parent_jar[name.to_s]
+          parse name, data
+        end
       end
 
       def []=(name, options)
         if options.is_a?(Hash)
           options.symbolize_keys!
         else
-          options = { :value => options }
+          options = { value: options }
         end
 
-        options[:expires] = 20.years.from_now
+        commit(options)
         @parent_jar[name] = options
       end
+
+      protected
+        def request; @parent_jar.request; end
+
+      private
+        def parse(name, data); data; end
+        def commit(options); end
+    end
+
+    class PermanentCookieJar < AbstractCookieJar # :nodoc:
+      private
+        def commit(options)
+          options[:expires] = 20.years.from_now
+        end
     end
 
-    class JsonSerializer
+    class JsonSerializer # :nodoc:
       def self.load(value)
         ActiveSupport::JSON.decode(value)
       end
@@ -402,12 +473,12 @@ module ActionDispatch
       end
     end
 
-    module SerializedCookieJars
+    module SerializedCookieJars # :nodoc:
       MARSHAL_SIGNATURE = "\x04\x08".freeze
 
       protected
         def needs_migration?(value)
-          @options[:serializer] == :hybrid && value.start_with?(MARSHAL_SIGNATURE)
+          request.cookies_serializer == :hybrid && value.start_with?(MARSHAL_SIGNATURE)
         end
 
         def serialize(value)
@@ -427,7 +498,7 @@ module ActionDispatch
         end
 
         def serializer
-          serializer = @options[:serializer] || :marshal
+          serializer = request.cookies_serializer || :marshal
           case serializer
           when :marshal
             Marshal
@@ -439,103 +510,71 @@ module ActionDispatch
         end
 
         def digest
-          @options[:digest] || 'SHA1'
+          request.cookies_digest || 'SHA1'
+        end
+
+        def key_generator
+          request.key_generator
         end
     end
 
-    class SignedCookieJar #:nodoc:
-      include ChainedCookieJars
+    class SignedCookieJar < AbstractCookieJar # :nodoc:
       include SerializedCookieJars
 
-      def initialize(parent_jar, key_generator, options = {})
-        @parent_jar = parent_jar
-        @options = options
-        secret = key_generator.generate_key(@options[:signed_cookie_salt])
+      def initialize(parent_jar)
+        super
+        secret = key_generator.generate_key(request.signed_cookie_salt)
         @verifier = ActiveSupport::MessageVerifier.new(secret, digest: digest, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
       end
 
-      def [](name)
-        if signed_message = @parent_jar[name]
-          deserialize name, verify(signed_message)
+      private
+        def parse(name, signed_message)
+          deserialize name, @verifier.verified(signed_message)
         end
-      end
 
-      def []=(name, options)
-        if options.is_a?(Hash)
-          options.symbolize_keys!
+        def commit(options)
           options[:value] = @verifier.generate(serialize(options[:value]))
-        else
-          options = { :value => @verifier.generate(serialize(options)) }
-        end
-
-        raise CookieOverflow if options[:value].bytesize > MAX_COOKIE_SIZE
-        @parent_jar[name] = options
-      end
 
-      private
-        def verify(signed_message)
-          @verifier.verify(signed_message)
-        rescue ActiveSupport::MessageVerifier::InvalidSignature
-          nil
+          raise CookieOverflow if options[:value].bytesize > MAX_COOKIE_SIZE
         end
     end
 
     # UpgradeLegacySignedCookieJar is used instead of SignedCookieJar if
     # secrets.secret_token and secrets.secret_key_base are both set. It reads
-    # legacy cookies signed with the old dummy key generator and re-saves
-    # them using the new key generator to provide a smooth upgrade path.
+    # legacy cookies signed with the old dummy key generator and signs and
+    # re-saves them using the new key generator to provide a smooth upgrade path.
     class UpgradeLegacySignedCookieJar < SignedCookieJar #:nodoc:
       include VerifyAndUpgradeLegacySignedMessage
-
-      def [](name)
-        if signed_message = @parent_jar[name]
-          deserialize(name, verify(signed_message)) || verify_and_upgrade_legacy_signed_message(name, signed_message)
-        end
-      end
     end
 
-    class EncryptedCookieJar #:nodoc:
-      include ChainedCookieJars
+    class EncryptedCookieJar < AbstractCookieJar # :nodoc:
       include SerializedCookieJars
 
-      def initialize(parent_jar, key_generator, options = {})
+      def initialize(parent_jar)
+        super
+
         if ActiveSupport::LegacyKeyGenerator === key_generator
           raise "You didn't set secrets.secret_key_base, which is required for this cookie jar. " +
             "Read the upgrade documentation to learn more about this new config option."
         end
 
-        @parent_jar = parent_jar
-        @options = options
-        secret = key_generator.generate_key(@options[:encrypted_cookie_salt])
-        sign_secret = key_generator.generate_key(@options[:encrypted_signed_cookie_salt])
+        secret = key_generator.generate_key(request.encrypted_cookie_salt || '')
+        sign_secret = key_generator.generate_key(request.encrypted_signed_cookie_salt || '')
         @encryptor = ActiveSupport::MessageEncryptor.new(secret, sign_secret, digest: digest, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
       end
 
-      def [](name)
-        if encrypted_message = @parent_jar[name]
-          deserialize name, decrypt_and_verify(encrypted_message)
-        end
-      end
-
-      def []=(name, options)
-        if options.is_a?(Hash)
-          options.symbolize_keys!
-        else
-          options = { :value => options }
-        end
-
-        options[:value] = @encryptor.encrypt_and_sign(serialize(options[:value]))
-
-        raise CookieOverflow if options[:value].bytesize > MAX_COOKIE_SIZE
-        @parent_jar[name] = options
-      end
-
       private
-        def decrypt_and_verify(encrypted_message)
-          @encryptor.decrypt_and_verify(encrypted_message)
+        def parse(name, encrypted_message)
+          deserialize name, @encryptor.decrypt_and_verify(encrypted_message)
         rescue ActiveSupport::MessageVerifier::InvalidSignature, ActiveSupport::MessageEncryptor::InvalidMessage
           nil
         end
+
+        def commit(options)
+          options[:value] = @encryptor.encrypt_and_sign(serialize(options[:value]))
+
+          raise CookieOverflow if options[:value].bytesize > MAX_COOKIE_SIZE
+        end
     end
 
     # UpgradeLegacyEncryptedCookieJar is used by ActionDispatch::Session::CookieStore
@@ -544,12 +583,6 @@ module ActionDispatch
     # encrypts and re-saves them using the new key generator to provide a smooth upgrade path.
     class UpgradeLegacyEncryptedCookieJar < EncryptedCookieJar #:nodoc:
       include VerifyAndUpgradeLegacySignedMessage
-
-      def [](name)
-        if encrypted_or_signed_message = @parent_jar[name]
-          deserialize(name, decrypt_and_verify(encrypted_or_signed_message)) || verify_and_upgrade_legacy_signed_message(name, encrypted_or_signed_message)
-        end
-      end
     end
 
     def initialize(app)
@@ -557,9 +590,12 @@ module ActionDispatch
     end
 
     def call(env)
+      request = ActionDispatch::Request.new env
+
       status, headers, body = @app.call(env)
 
-      if cookie_jar = env['action_dispatch.cookies']
+      if request.have_cookie_jar?
+        cookie_jar = request.cookie_jar
         unless cookie_jar.committed?
           cookie_jar.write(headers)
           if headers[HTTP_HEADER].respond_to?(:join)
diff --git a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
index 9082aac271..66bb74b9c5 100644
--- a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
@@ -44,6 +44,7 @@ module ActionDispatch
     end
 
     def call(env)
+      request = ActionDispatch::Request.new env
       _, headers, body = response = @app.call(env)
 
       if headers['X-Cascade'] == 'pass'
@@ -53,18 +54,18 @@ module ActionDispatch
 
       response
     rescue Exception => exception
-      raise exception if env['action_dispatch.show_exceptions'] == false
-      render_exception(env, exception)
+      raise exception unless request.show_exceptions?
+      render_exception(request, exception)
     end
 
     private
 
-    def render_exception(env, exception)
-      wrapper = ExceptionWrapper.new(env, exception)
-      log_error(env, wrapper)
+    def render_exception(request, exception)
+      backtrace_cleaner = request.get_header('action_dispatch.backtrace_cleaner')
+      wrapper = ExceptionWrapper.new(backtrace_cleaner, exception)
+      log_error(request, wrapper)
 
-      if env['action_dispatch.show_detailed_exceptions']
-        request = Request.new(env)
+      if request.get_header('action_dispatch.show_detailed_exceptions')
         traces = wrapper.traces
 
         trace_to_show = 'Application Trace'
@@ -106,8 +107,8 @@ module ActionDispatch
       [status, {'Content-Type' => "#{format}; charset=#{Response.default_charset}", 'Content-Length' => body.bytesize.to_s}, [body]]
     end
 
-    def log_error(env, wrapper)
-      logger = logger(env)
+    def log_error(request, wrapper)
+      logger = logger(request)
       return unless logger
 
       exception = wrapper.exception
@@ -123,8 +124,8 @@ module ActionDispatch
       end
     end
 
-    def logger(env)
-      env['action_dispatch.logger'] || stderr_logger
+    def logger(request)
+      request.logger || stderr_logger
     end
 
     def stderr_logger
diff --git a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
index a4862e33aa..5fd984cd07 100644
--- a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
+++ b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
@@ -1,5 +1,6 @@
 require 'action_controller/metal/exceptions'
 require 'active_support/core_ext/module/attribute_accessors'
+require 'rack/utils'
 
 module ActionDispatch
   class ExceptionWrapper
@@ -16,7 +17,9 @@ module ActionDispatch
       'ActionController::InvalidCrossOriginRequest'   => :unprocessable_entity,
       'ActionDispatch::ParamsParser::ParseError'      => :bad_request,
       'ActionController::BadRequest'                  => :bad_request,
-      'ActionController::ParameterMissing'            => :bad_request
+      'ActionController::ParameterMissing'            => :bad_request,
+      'Rack::Utils::ParameterTypeError'               => :bad_request,
+      'Rack::Utils::InvalidParameterError'            => :bad_request
     )
 
     cattr_accessor :rescue_templates
@@ -28,10 +31,10 @@ module ActionDispatch
       'ActionView::Template::Error'         => 'template_error'
     )
 
-    attr_reader :env, :exception, :line_number, :file
+    attr_reader :backtrace_cleaner, :exception, :line_number, :file
 
-    def initialize(env, exception)
-      @env = env
+    def initialize(backtrace_cleaner, exception)
+      @backtrace_cleaner = backtrace_cleaner
       @exception = original_exception(exception)
 
       expand_backtrace if exception.is_a?(SyntaxError) || exception.try(:original_exception).try(:is_a?, SyntaxError)
@@ -58,7 +61,7 @@ module ActionDispatch
     end
 
     def traces
-      appplication_trace_with_ids = []
+      application_trace_with_ids = []
       framework_trace_with_ids = []
       full_trace_with_ids = []
 
@@ -66,7 +69,7 @@ module ActionDispatch
         trace_with_id = { id: idx, trace: trace }
 
         if application_trace.include?(trace)
-          appplication_trace_with_ids << trace_with_id
+          application_trace_with_ids << trace_with_id
         else
           framework_trace_with_ids << trace_with_id
         end
@@ -75,7 +78,7 @@ module ActionDispatch
       end
 
       {
-        "Application Trace" => appplication_trace_with_ids,
+        "Application Trace" => application_trace_with_ids,
         "Framework Trace" => framework_trace_with_ids,
         "Full Trace" => full_trace_with_ids
       }
@@ -87,8 +90,7 @@ module ActionDispatch
 
     def source_extracts
       backtrace.map do |trace|
-        file, line = trace.split(":")
-        line_number = line.to_i
+        file, line_number = extract_file_and_line_number(trace)
 
         {
           code: source_fragment(file, line_number),
@@ -123,10 +125,6 @@ module ActionDispatch
       end
     end
 
-    def backtrace_cleaner
-      @backtrace_cleaner ||= @env['action_dispatch.backtrace_cleaner']
-    end
-
     def source_fragment(path, line)
       return unless Rails.respond_to?(:root) && Rails.root
       full_path = Rails.root.join(path)
@@ -139,6 +137,13 @@ module ActionDispatch
       end
     end
 
+    def extract_file_and_line_number(trace)
+      # Split by the first colon followed by some digits, which works for both
+      # Windows and Unix path styles.
+      file, line = trace.match(/^(.+?):(\d+).*$/, &:captures) || trace
+      [file, line.to_i]
+    end
+
     def expand_backtrace
       @exception.backtrace.unshift(
         @exception.to_s.split("\n")
diff --git a/actionpack/lib/action_dispatch/middleware/flash.rb b/actionpack/lib/action_dispatch/middleware/flash.rb
index a7f95150a4..c51dcd542a 100644
--- a/actionpack/lib/action_dispatch/middleware/flash.rb
+++ b/actionpack/lib/action_dispatch/middleware/flash.rb
@@ -1,15 +1,6 @@
 require 'active_support/core_ext/hash/keys'
 
 module ActionDispatch
-  class Request < Rack::Request
-    # Access the contents of the flash. Use <tt>flash["notice"]</tt> to
-    # read a notice you put there or <tt>flash["notice"] = "hello"</tt>
-    # to put a new one.
-    def flash
-      @env[Flash::KEY] ||= Flash::FlashHash.from_session_value(session["flash"])
-    end
-  end
-
   # The flash provides a way to pass temporary primitive-types (String, Array, Hash) between actions. Anything you place in the flash will be exposed
   # to the very next action and then cleared out. This is a great way of doing notices and alerts, such as a create
   # action that sets <tt>flash[:notice] = "Post successfully created"</tt> before redirecting to a display action that can
@@ -47,6 +38,40 @@ module ActionDispatch
   class Flash
     KEY = 'action_dispatch.request.flash_hash'.freeze
 
+    module RequestMethods
+      # Access the contents of the flash. Use <tt>flash["notice"]</tt> to
+      # read a notice you put there or <tt>flash["notice"] = "hello"</tt>
+      # to put a new one.
+      def flash
+        flash = flash_hash
+        return flash if flash
+        self.flash = Flash::FlashHash.from_session_value(session["flash"])
+      end
+
+      def flash=(flash)
+        set_header Flash::KEY, flash
+      end
+
+      def flash_hash # :nodoc:
+        get_header Flash::KEY
+      end
+
+      def commit_flash # :nodoc:
+        session    = self.session || {}
+        flash_hash = self.flash_hash
+
+        if flash_hash && (flash_hash.present? || session.key?('flash'))
+          session["flash"] = flash_hash.to_session_value
+          self.flash = flash_hash.dup
+        end
+
+        if (!session.respond_to?(:loaded?) || session.loaded?) && # (reset_session uses {}, which doesn't implement #loaded?)
+            session.key?('flash') && session['flash'].nil?
+          session.delete('flash')
+        end
+      end
+    end
+
     class FlashNow #:nodoc:
       attr_accessor :flash
 
@@ -80,24 +105,30 @@ module ActionDispatch
       include Enumerable
 
       def self.from_session_value(value) #:nodoc:
-        flash = case value
-                when FlashHash # Rails 3.1, 3.2
-                  new(value.instance_variable_get(:@flashes), value.instance_variable_get(:@used))
-                when Hash # Rails 4.0
-                  new(value['flashes'], value['discard'])
-                else
-                  new
-                end
-
-        flash.tap(&:sweep)
-      end
-      
-      # Builds a hash containing the discarded values and the hashes
-      # representing the flashes.
-      # If there are no values in @flashes, returns nil.
+        case value
+        when FlashHash # Rails 3.1, 3.2
+          flashes = value.instance_variable_get(:@flashes)
+          if discard = value.instance_variable_get(:@used)
+            flashes.except!(*discard)
+          end
+          new(flashes, flashes.keys)
+        when Hash # Rails 4.0
+          flashes = value['flashes']
+          if discard = value['discard']
+            flashes.except!(*discard)
+          end
+          new(flashes, flashes.keys)
+        else
+          new
+        end
+      end
+
+      # Builds a hash containing the flashes to keep for the next request.
+      # If there are none to keep, returns nil.
       def to_session_value #:nodoc:
-        return nil if empty?
-        {'discard' => @discard.to_a, 'flashes' => @flashes}
+        flashes_to_keep = @flashes.except(*@discard)
+        return nil if flashes_to_keep.empty?
+        {'flashes' => flashes_to_keep}
       end
 
       def initialize(flashes = {}, discard = []) #:nodoc:
@@ -252,25 +283,10 @@ module ActionDispatch
       end
     end
 
-    def initialize(app)
-      @app = app
-    end
-
-    def call(env)
-      @app.call(env)
-    ensure
-      session    = Request::Session.find(env) || {}
-      flash_hash = env[KEY]
-
-      if flash_hash && (flash_hash.present? || session.key?('flash'))
-        session["flash"] = flash_hash.to_session_value
-        env[KEY] = flash_hash.dup
-      end
+    def self.new(app) app; end
+  end
 
-      if (!session.respond_to?(:loaded?) || session.loaded?) && # (reset_session uses {}, which doesn't implement #loaded?)
-        session.key?('flash') && session['flash'].nil?
-        session.delete('flash')
-      end
-    end
+  class Request
+    prepend Flash::RequestMethods
   end
 end
diff --git a/actionpack/lib/action_dispatch/middleware/load_interlock.rb b/actionpack/lib/action_dispatch/middleware/load_interlock.rb
new file mode 100644
index 0000000000..07f498319c
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/load_interlock.rb
@@ -0,0 +1,21 @@
+require 'active_support/dependencies'
+require 'rack/body_proxy'
+
+module ActionDispatch
+  class LoadInterlock
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      interlock = ActiveSupport::Dependencies.interlock
+      interlock.start_running
+      response = @app.call(env)
+      body = Rack::BodyProxy.new(response[2]) { interlock.done_running }
+      response[2] = body
+      response
+    ensure
+      interlock.done_running unless body
+    end
+  end
+end
diff --git a/actionpack/lib/action_dispatch/middleware/params_parser.rb b/actionpack/lib/action_dispatch/middleware/params_parser.rb
index 29d43faeed..18af0a583a 100644
--- a/actionpack/lib/action_dispatch/middleware/params_parser.rb
+++ b/actionpack/lib/action_dispatch/middleware/params_parser.rb
@@ -1,9 +1,14 @@
-require 'active_support/core_ext/hash/conversions'
 require 'action_dispatch/http/request'
-require 'active_support/core_ext/hash/indifferent_access'
 
 module ActionDispatch
+  # ActionDispatch::ParamsParser works for all the requests having any Content-Length
+  # (like POST). It takes raw data from the request and puts it through the parser
+  # that is picked based on Content-Type header.
+  #
+  # In case of any error while parsing data ParamsParser::ParseError is raised.
   class ParamsParser
+    # Raised when raw data from the request cannot be parsed by the parser
+    # defined for request's content mime type.
     class ParseError < StandardError
       attr_reader :original_exception
 
@@ -13,48 +18,13 @@ module ActionDispatch
       end
     end
 
-    DEFAULT_PARSERS = { Mime::JSON => :json }
-
-    def initialize(app, parsers = {})
-      @app, @parsers = app, DEFAULT_PARSERS.merge(parsers)
+    # Create a new +ParamsParser+ middleware instance.
+    #
+    # The +parsers+ argument can take Hash of parsers where key is identifying
+    # content mime type, and value is a lambda that is going to process data.
+    def self.new(app, parsers = {})
+      ActionDispatch::Request.parameter_parsers = ActionDispatch::Request::DEFAULT_PARSERS.merge(parsers)
+      app
     end
-
-    def call(env)
-      if params = parse_formatted_parameters(env)
-        env["action_dispatch.request.request_parameters"] = params
-      end
-
-      @app.call(env)
-    end
-
-    private
-      def parse_formatted_parameters(env)
-        request = Request.new(env)
-
-        return false if request.content_length.zero?
-
-        strategy = @parsers[request.content_mime_type]
-
-        return false unless strategy
-
-        case strategy
-        when Proc
-          strategy.call(request.raw_post)
-        when :json
-          data = ActiveSupport::JSON.decode(request.raw_post)
-          data = {:_json => data} unless data.is_a?(Hash)
-          Request::Utils.deep_munge(data).with_indifferent_access
-        else
-          false
-        end
-      rescue => e # JSON or Ruby code block errors
-        logger(env).debug "Error occurred while parsing request parameters.\nContents:\n\n#{request.raw_post}"
-
-        raise ParseError.new(e.message, e)
-      end
-
-      def logger(env)
-        env['action_dispatch.logger'] || ActiveSupport::Logger.new($stderr)
-      end
   end
 end
diff --git a/actionpack/lib/action_dispatch/middleware/public_exceptions.rb b/actionpack/lib/action_dispatch/middleware/public_exceptions.rb
index 040cb215b7..0f27984550 100644
--- a/actionpack/lib/action_dispatch/middleware/public_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/public_exceptions.rb
@@ -17,10 +17,10 @@ module ActionDispatch
     end
 
     def call(env)
-      status       = env["PATH_INFO"][1..-1]
       request      = ActionDispatch::Request.new(env)
+      status       = request.path_info[1..-1].to_i
       content_type = request.formats.first
-      body         = { :status => status, :error => Rack::Utils::HTTP_STATUS_CODES.fetch(status.to_i, Rack::Utils::HTTP_STATUS_CODES[500]) }
+      body         = { :status => status, :error => Rack::Utils::HTTP_STATUS_CODES.fetch(status, Rack::Utils::HTTP_STATUS_CODES[500]) }
 
       render(status, content_type, body)
     end
diff --git a/actionpack/lib/action_dispatch/middleware/reloader.rb b/actionpack/lib/action_dispatch/middleware/reloader.rb
index 15b5a48535..af9a29eb07 100644
--- a/actionpack/lib/action_dispatch/middleware/reloader.rb
+++ b/actionpack/lib/action_dispatch/middleware/reloader.rb
@@ -1,5 +1,3 @@
-require 'active_support/deprecation/reporting'
-
 module ActionDispatch
   # ActionDispatch::Reloader provides prepare and cleanup callbacks,
   # intended to assist with code reloading during development.
@@ -11,9 +9,9 @@ module ActionDispatch
   # the response body. This is important for streaming responses such as the
   # following:
   #
-  #     self.response_body = lambda { |response, output|
+  #     self.response_body = -> (response, output) do
   #       # code here which refers to application models
-  #     }
+  #     end
   #
   # Cleanup callbacks will not be called until after the response_body lambda
   # is evaluated, ensuring that it can refer to application models and other
diff --git a/actionpack/lib/action_dispatch/middleware/remote_ip.rb b/actionpack/lib/action_dispatch/middleware/remote_ip.rb
index 7c4236518d..aee2334da9 100644
--- a/actionpack/lib/action_dispatch/middleware/remote_ip.rb
+++ b/actionpack/lib/action_dispatch/middleware/remote_ip.rb
@@ -74,18 +74,19 @@ module ActionDispatch
     # requests. For those requests that do need to know the IP, the
     # GetIp#calculate_ip method will calculate the memoized client IP address.
     def call(env)
-      env["action_dispatch.remote_ip"] = GetIp.new(env, self)
-      @app.call(env)
+      req = ActionDispatch::Request.new env
+      req.remote_ip = GetIp.new(req, check_ip, proxies)
+      @app.call(req.env)
     end
 
     # The GetIp class exists as a way to defer processing of the request data
     # into an actual IP address. If the ActionDispatch::Request#remote_ip method
     # is called, this class will calculate the value and then memoize it.
     class GetIp
-      def initialize(env, middleware)
-        @env      = env
-        @check_ip = middleware.check_ip
-        @proxies  = middleware.proxies
+      def initialize(req, check_ip, proxies)
+        @req      = req
+        @check_ip = check_ip
+        @proxies  = proxies
       end
 
       # Sort through the various IP address headers, looking for the IP most
@@ -108,11 +109,11 @@ module ActionDispatch
       # the last address left, which was presumably set by one of those proxies.
       def calculate_ip
         # Set by the Rack web server, this is a single value.
-        remote_addr = ips_from('REMOTE_ADDR').last
+        remote_addr = ips_from(@req.remote_addr).last
 
         # Could be a CSV list and/or repeated headers that were concatenated.
-        client_ips    = ips_from('HTTP_CLIENT_IP').reverse
-        forwarded_ips = ips_from('HTTP_X_FORWARDED_FOR').reverse
+        client_ips    = ips_from(@req.client_ip).reverse
+        forwarded_ips = ips_from(@req.x_forwarded_for).reverse
 
         # +Client-Ip+ and +X-Forwarded-For+ should not, generally, both be set.
         # If they are both set, it means that this request passed through two
@@ -123,8 +124,8 @@ module ActionDispatch
         if should_check_ip && !forwarded_ips.include?(client_ips.last)
           # We don't know which came from the proxy, and which from the user
           raise IpSpoofAttackError, "IP spoofing attack?! " +
-            "HTTP_CLIENT_IP=#{@env['HTTP_CLIENT_IP'].inspect} " +
-            "HTTP_X_FORWARDED_FOR=#{@env['HTTP_X_FORWARDED_FOR'].inspect}"
+            "HTTP_CLIENT_IP=#{@req.client_ip.inspect} " +
+            "HTTP_X_FORWARDED_FOR=#{@req.x_forwarded_for.inspect}"
         end
 
         # We assume these things about the IP headers:
@@ -147,8 +148,9 @@ module ActionDispatch
     protected
 
       def ips_from(header)
+        return [] unless header
         # Split the comma-separated list into an array of strings
-        ips = @env[header] ? @env[header].strip.split(/[,\s]+/) : []
+        ips = header.strip.split(/[,\s]+/)
         ips.select do |ip|
           begin
             # Only return IPs that are valid according to the IPAddr#new method
diff --git a/actionpack/lib/action_dispatch/middleware/request_id.rb b/actionpack/lib/action_dispatch/middleware/request_id.rb
index 25658bac3d..1555ff72af 100644
--- a/actionpack/lib/action_dispatch/middleware/request_id.rb
+++ b/actionpack/lib/action_dispatch/middleware/request_id.rb
@@ -3,7 +3,7 @@ require 'active_support/core_ext/string/access'
 
 module ActionDispatch
   # Makes a unique request id available to the action_dispatch.request_id env variable (which is then accessible through
-  # ActionDispatch::Request#uuid) and sends the same id to the client via the X-Request-Id header.
+  # ActionDispatch::Request#uuid or the alias ActionDispatch::Request#request_id) and sends the same id to the client via the X-Request-Id header.
   #
   # The unique request id is either based on the X-Request-Id header in the request, which would typically be generated
   # by a firewall, load balancer, or the web server, or, if this header is not available, a random uuid. If the
@@ -12,19 +12,24 @@ module ActionDispatch
   # The unique request id can be used to trace a request end-to-end and would typically end up being part of log files
   # from multiple pieces of the stack.
   class RequestId
+    X_REQUEST_ID = "X-Request-Id".freeze # :nodoc:
+
     def initialize(app)
       @app = app
     end
 
     def call(env)
-      env["action_dispatch.request_id"] = external_request_id(env) || internal_request_id
-      @app.call(env).tap { |_status, headers, _body| headers["X-Request-Id"] = env["action_dispatch.request_id"] }
+      req = ActionDispatch::Request.new env
+      req.request_id = make_request_id(req.x_request_id)
+      @app.call(env).tap { |_status, headers, _body| headers[X_REQUEST_ID] = req.request_id }
     end
 
     private
-      def external_request_id(env)
-        if request_id = env["HTTP_X_REQUEST_ID"].presence
-          request_id.gsub(/[^\w\-]/, "").first(255)
+      def make_request_id(request_id)
+        if request_id.presence
+          request_id.gsub(/[^\w\-]/, "".freeze).first(255)
+        else
+          internal_request_id
         end
       end
 
diff --git a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
index 84df55fd5a..9e50fea3fc 100644
--- a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
@@ -36,6 +36,11 @@ module ActionDispatch
         @default_options.delete(:sidbits)
         @default_options.delete(:secure_random)
       end
+
+      private
+      def make_request(env)
+        ActionDispatch::Request.new env
+      end
     end
 
     module StaleSessionCheck
@@ -65,8 +70,8 @@ module ActionDispatch
     end
 
     module SessionObject # :nodoc:
-      def prepare_session(env)
-        Request::Session.create(self, env, @default_options)
+      def prepare_session(req)
+        Request::Session.create(self, req, @default_options)
       end
 
       def loaded_session?(session)
@@ -74,15 +79,14 @@ module ActionDispatch
       end
     end
 
-    class AbstractStore < Rack::Session::Abstract::ID
+    class AbstractStore < Rack::Session::Abstract::Persisted
       include Compatibility
       include StaleSessionCheck
       include SessionObject
 
       private
 
-      def set_cookie(env, session_id, cookie)
-        request = ActionDispatch::Request.new(env)
+      def set_cookie(request, session_id, cookie)
         request.cookie_jar[key] = cookie
       end
     end
diff --git a/actionpack/lib/action_dispatch/middleware/session/cache_store.rb b/actionpack/lib/action_dispatch/middleware/session/cache_store.rb
index 625050dc4b..589ae46e38 100644
--- a/actionpack/lib/action_dispatch/middleware/session/cache_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/cache_store.rb
@@ -2,12 +2,15 @@ require 'action_dispatch/middleware/session/abstract_store'
 
 module ActionDispatch
   module Session
-    # Session store that uses an ActiveSupport::Cache::Store to store the sessions. This store is most useful
+    # A session store that uses an ActiveSupport::Cache::Store to store the sessions. This store is most useful
     # if you don't store critical data in your sessions and you don't need them to live for extended periods
     # of time.
+    #
+    # ==== Options
+    # * <tt>cache</tt>         - The cache to use. If it is not specified, <tt>Rails.cache</tt> will be used.
+    # * <tt>expire_after</tt>  - The length of time a session will be stored before automatically expiring.
+    #   By default, the <tt>:expires_in</tt> option of the cache is used.
     class CacheStore < AbstractStore
-      # Create a new store. The cache to use can be passed in the <tt>:cache</tt> option. If it is
-      # not specified, <tt>Rails.cache</tt> will be used.
       def initialize(app, options = {})
         @cache = options[:cache] || Rails.cache
         options[:expire_after] ||= @cache.options[:expires_in]
@@ -15,7 +18,7 @@ module ActionDispatch
       end
 
       # Get a session from the cache.
-      def get_session(env, sid)
+      def find_session(env, sid)
         unless sid and session = @cache.read(cache_key(sid))
           sid, session = generate_sid, {}
         end
@@ -23,7 +26,7 @@ module ActionDispatch
       end
 
       # Set a session in the cache.
-      def set_session(env, sid, session, options)
+      def write_session(env, sid, session, options)
         key = cache_key(sid)
         if session
           @cache.write(key, session, :expires_in => options[:expire_after])
@@ -34,7 +37,7 @@ module ActionDispatch
       end
 
       # Remove a session from the cache.
-      def destroy_session(env, sid, options)
+      def delete_session(env, sid, options)
         @cache.delete(cache_key(sid))
         generate_sid
       end
diff --git a/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb b/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
index ed25c67ae5..0e636b8257 100644
--- a/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
@@ -52,25 +52,31 @@ module ActionDispatch
     # JavaScript before upgrading.
     #
     # Note that changing the secret key will invalidate all existing sessions!
-    class CookieStore < Rack::Session::Abstract::ID
-      include Compatibility
-      include StaleSessionCheck
-      include SessionObject
-
+    #
+    # Because CookieStore extends Rack::Session::Abstract::Persisted, many of the
+    # options described there can be used to customize the session cookie that
+    # is generated. For example:
+    #
+    #   Rails.application.config.session_store :cookie_store, expire_after: 14.days
+    #
+    # would set the session cookie to expire automatically 14 days after creation.
+    # Other useful options include <tt>:key</tt>, <tt>:secure</tt> and
+    # <tt>:httponly</tt>.
+    class CookieStore < AbstractStore
       def initialize(app, options={})
         super(app, options.merge!(:cookie_only => true))
       end
 
-      def destroy_session(env, session_id, options)
+      def delete_session(req, session_id, options)
         new_sid = generate_sid unless options[:drop]
         # Reset hash and Assign the new session id
-        env["action_dispatch.request.unsigned_session_cookie"] = new_sid ? { "session_id" => new_sid } : {}
+        req.set_header("action_dispatch.request.unsigned_session_cookie", new_sid ? { "session_id" => new_sid } : {})
         new_sid
       end
 
-      def load_session(env)
+      def load_session(req)
         stale_session_check! do
-          data = unpacked_cookie_data(env)
+          data = unpacked_cookie_data(req)
           data = persistent_session_id!(data)
           [data["session_id"], data]
         end
@@ -78,20 +84,21 @@ module ActionDispatch
 
       private
 
-      def extract_session_id(env)
+      def extract_session_id(req)
         stale_session_check! do
-          unpacked_cookie_data(env)["session_id"]
+          unpacked_cookie_data(req)["session_id"]
         end
       end
 
-      def unpacked_cookie_data(env)
-        env["action_dispatch.request.unsigned_session_cookie"] ||= begin
-          stale_session_check! do
-            if data = get_cookie(env)
+      def unpacked_cookie_data(req)
+        req.fetch_header("action_dispatch.request.unsigned_session_cookie") do |k|
+          v = stale_session_check! do
+            if data = get_cookie(req)
               data.stringify_keys!
             end
             data || {}
           end
+          req.set_header k, v
         end
       end
 
@@ -101,21 +108,20 @@ module ActionDispatch
         data
       end
 
-      def set_session(env, sid, session_data, options)
+      def write_session(req, sid, session_data, options)
         session_data["session_id"] = sid
         session_data
       end
 
-      def set_cookie(env, session_id, cookie)
-        cookie_jar(env)[@key] = cookie
+      def set_cookie(request, session_id, cookie)
+        cookie_jar(request)[@key] = cookie
       end
 
-      def get_cookie(env)
-        cookie_jar(env)[@key]
+      def get_cookie(req)
+        cookie_jar(req)[@key]
       end
 
-      def cookie_jar(env)
-        request = ActionDispatch::Request.new(env)
+      def cookie_jar(request)
         request.cookie_jar.signed_or_encrypted
       end
     end
diff --git a/actionpack/lib/action_dispatch/middleware/session/mem_cache_store.rb b/actionpack/lib/action_dispatch/middleware/session/mem_cache_store.rb
index b4d6629c35..cb19786f0b 100644
--- a/actionpack/lib/action_dispatch/middleware/session/mem_cache_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/mem_cache_store.rb
@@ -8,6 +8,10 @@ end
 
 module ActionDispatch
   module Session
+    # A session store that uses MemCache to implement storage.
+    #
+    # ==== Options
+    # * <tt>expire_after</tt>  - The length of time a session will be stored before automatically expiring.
     class MemCacheStore < Rack::Session::Dalli
       include Compatibility
       include StaleSessionCheck
diff --git a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
index f0779279c1..64695f9738 100644
--- a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
@@ -27,24 +27,26 @@ module ActionDispatch
     end
 
     def call(env)
+      request = ActionDispatch::Request.new env
       @app.call(env)
     rescue Exception => exception
-      if env['action_dispatch.show_exceptions'] == false
-        raise exception
+      if request.show_exceptions?
+        render_exception(request, exception)
       else
-        render_exception(env, exception)
+        raise exception
       end
     end
 
     private
 
-    def render_exception(env, exception)
-      wrapper = ExceptionWrapper.new(env, exception)
+    def render_exception(request, exception)
+      backtrace_cleaner = request.get_header 'action_dispatch.backtrace_cleaner'
+      wrapper = ExceptionWrapper.new(backtrace_cleaner, exception)
       status  = wrapper.status_code
-      env["action_dispatch.exception"] = wrapper.exception
-      env["action_dispatch.original_path"] = env["PATH_INFO"]
-      env["PATH_INFO"] = "/#{status}"
-      response = @exceptions_app.call(env)
+      request.set_header "action_dispatch.exception", wrapper.exception
+      request.set_header "action_dispatch.original_path", request.path_info
+      request.path_info = "/#{status}"
+      response = @exceptions_app.call(request.env)
       response[1]['X-Cascade'] == 'pass' ? pass_response(status) : response
     rescue Exception => failsafe_error
       $stderr.puts "Error during failsafe response: #{failsafe_error}\n  #{failsafe_error.backtrace * "\n  "}"
diff --git a/actionpack/lib/action_dispatch/middleware/ssl.rb b/actionpack/lib/action_dispatch/middleware/ssl.rb
index 0c7caef25d..47f475559a 100644
--- a/actionpack/lib/action_dispatch/middleware/ssl.rb
+++ b/actionpack/lib/action_dispatch/middleware/ssl.rb
@@ -1,72 +1,129 @@
 module ActionDispatch
+  # This middleware is added to the stack when `config.force_ssl = true`.
+  # It does three jobs to enforce secure HTTP requests:
+  #
+  #   1. TLS redirect. http:// requests are permanently redirected to https://
+  #      with the same URL host, path, etc. Pass `:host` and/or `:port` to
+  #      modify the destination URL. This is always enabled.
+  #
+  #   2. Secure cookies. Sets the `secure` flag on cookies to tell browsers they
+  #      mustn't be sent along with http:// requests. This is always enabled.
+  #
+  #   3. HTTP Strict Transport Security (HSTS). Tells the browser to remember
+  #      this site as TLS-only and automatically redirect non-TLS requests.
+  #      Enabled by default. Pass `hsts: false` to disable.
+  #
+  # Configure HSTS with `hsts: { … }`:
+  #   * `expires`: How long, in seconds, these settings will stick. Defaults to
+  #     `180.days` (recommended). The minimum required to qualify for browser
+  #     preload lists is `18.weeks`.
+  #   * `subdomains`: Set to `true` to tell the browser to apply these settings
+  #     to all subdomains. This protects your cookies from interception by a
+  #     vulnerable site on a subdomain. Defaults to `false`.
+  #   * `preload`: Advertise that this site may be included in browsers'
+  #     preloaded HSTS lists. HSTS protects your site on every visit *except the
+  #     first visit* since it hasn't seen your HSTS header yet. To close this
+  #     gap, browser vendors include a baked-in list of HSTS-enabled sites.
+  #     Go to https://hstspreload.appspot.com to submit your site for inclusion.
+  #
+  # Disabling HSTS: To turn off HSTS, omitting the header is not enough.
+  # Browsers will remember the original HSTS directive until it expires.
+  # Instead, use the header to tell browsers to expire HSTS immediately.
+  # Setting `hsts: false` is a shortcut for `hsts: { expires: 0 }`.
   class SSL
-    YEAR = 31536000
+    # Default to 180 days, the low end for https://www.ssllabs.com/ssltest/
+    # and greater than the 18-week requirement for browser preload lists.
+    HSTS_EXPIRES_IN = 15552000
 
     def self.default_hsts_options
-      { :expires => YEAR, :subdomains => false }
+      { expires: HSTS_EXPIRES_IN, subdomains: false, preload: false }
     end
 
-    def initialize(app, options = {})
+    def initialize(app, redirect: {}, hsts: {}, **options)
       @app = app
 
-      @hsts = options.fetch(:hsts, {})
-      @hsts = {} if @hsts == true
-      @hsts = self.class.default_hsts_options.merge(@hsts) if @hsts
+      if options[:host] || options[:port]
+        ActiveSupport::Deprecation.warn <<-end_warning.strip_heredoc
+          The `:host` and `:port` options are moving within `:redirect`:
+          `config.ssl_options = { redirect: { host: …, port: … }}`.
+        end_warning
+        @redirect = options.slice(:host, :port)
+      else
+        @redirect = redirect
+      end
 
-      @host    = options[:host]
-      @port    = options[:port]
+      @hsts_header = build_hsts_header(normalize_hsts_options(hsts))
     end
 
     def call(env)
-      request = Request.new(env)
+      request = Request.new env
 
       if request.ssl?
-        status, headers, body = @app.call(env)
-        headers = hsts_headers.merge(headers)
-        flag_cookies_as_secure!(headers)
-        [status, headers, body]
+        @app.call(env).tap do |status, headers, body|
+          set_hsts_header! headers
+          flag_cookies_as_secure! headers
+        end
       else
-        redirect_to_https(request)
+        redirect_to_https request
       end
     end
 
     private
-      def redirect_to_https(request)
-        host = @host || request.host
-        port = @port || request.port
-
-        location = "https://#{host}"
-        location << ":#{port}" if port != 80
-        location << request.fullpath
-
-        headers = { 'Content-Type' => 'text/html', 'Location' => location }
-
-        [301, headers, []]
+      def set_hsts_header!(headers)
+        headers['Strict-Transport-Security'.freeze] ||= @hsts_header
       end
 
-      # http://tools.ietf.org/html/draft-hodges-strict-transport-sec-02
-      def hsts_headers
-        if @hsts
-          value = "max-age=#{@hsts[:expires].to_i}"
-          value += "; includeSubDomains" if @hsts[:subdomains]
-          { 'Strict-Transport-Security' => value }
+      def normalize_hsts_options(options)
+        case options
+        # Explicitly disabling HSTS clears the existing setting from browsers
+        # by setting expiry to 0.
+        when false
+          self.class.default_hsts_options.merge(expires: 0)
+        # Default to enabled, with default options.
+        when nil, true
+          self.class.default_hsts_options
         else
-          {}
+          self.class.default_hsts_options.merge(options)
         end
       end
 
+      # http://tools.ietf.org/html/rfc6797#section-6.1
+      def build_hsts_header(hsts)
+        value = "max-age=#{hsts[:expires].to_i}"
+        value << "; includeSubDomains" if hsts[:subdomains]
+        value << "; preload" if hsts[:preload]
+        value
+      end
+
       def flag_cookies_as_secure!(headers)
-        if cookies = headers['Set-Cookie']
-          cookies = cookies.split("\n")
+        if cookies = headers['Set-Cookie'.freeze]
+          cookies = cookies.split("\n".freeze)
 
-          headers['Set-Cookie'] = cookies.map { |cookie|
+          headers['Set-Cookie'.freeze] = cookies.map { |cookie|
             if cookie !~ /;\s*secure\s*(;|$)/i
               "#{cookie}; secure"
             else
               cookie
             end
-          }.join("\n")
+          }.join("\n".freeze)
         end
       end
+
+      def redirect_to_https(request)
+        [ @redirect.fetch(:status, 301),
+          { 'Content-Type' => 'text/html',
+            'Location' => https_location_for(request) },
+          @redirect.fetch(:body, []) ]
+      end
+
+      def https_location_for(request)
+        host = @redirect[:host] || request.host
+        port = @redirect[:port] || request.port
+
+        location = "https://#{host}"
+        location << ":#{port}" if port != 80 && port != 443
+        location << request.fullpath
+        location
+      end
   end
 end
diff --git a/actionpack/lib/action_dispatch/middleware/stack.rb b/actionpack/lib/action_dispatch/middleware/stack.rb
index bbf734f103..90e2ae6802 100644
--- a/actionpack/lib/action_dispatch/middleware/stack.rb
+++ b/actionpack/lib/action_dispatch/middleware/stack.rb
@@ -4,36 +4,15 @@ require "active_support/dependencies"
 module ActionDispatch
   class MiddlewareStack
     class Middleware
-      attr_reader :args, :block, :name, :classcache
+      attr_reader :args, :block, :klass
 
-      def initialize(klass_or_name, *args, &block)
-        @klass = nil
-
-        if klass_or_name.respond_to?(:name)
-          @klass = klass_or_name
-          @name  = @klass.name
-        else
-          @name  = klass_or_name.to_s
-        end
-
-        @classcache = ActiveSupport::Dependencies::Reference
-        @args, @block = args, block
+      def initialize(klass, args, block)
+        @klass = klass
+        @args  = args
+        @block = block
       end
 
-      def klass
-        @klass || classcache[@name]
-      end
-
-      def ==(middleware)
-        case middleware
-        when Middleware
-          klass == middleware.klass
-        when Class
-          klass == middleware
-        else
-          normalize(@name) == normalize(middleware)
-        end
-      end
+      def name; klass.name; end
 
       def inspect
         klass.to_s
@@ -42,12 +21,6 @@ module ActionDispatch
       def build(app)
         klass.new(app, *args, &block)
       end
-
-    private
-
-      def normalize(object)
-        object.to_s.strip.sub(/^::/, '')
-      end
     end
 
     include Enumerable
@@ -75,19 +48,17 @@ module ActionDispatch
       middlewares[i]
     end
 
-    def unshift(*args, &block)
-      middleware = self.class::Middleware.new(*args, &block)
-      middlewares.unshift(middleware)
+    def unshift(klass, *args, &block)
+      middlewares.unshift(build_middleware(klass, args, block))
     end
 
     def initialize_copy(other)
       self.middlewares = other.middlewares.dup
     end
 
-    def insert(index, *args, &block)
+    def insert(index, klass, *args, &block)
       index = assert_index(index, :before)
-      middleware = self.class::Middleware.new(*args, &block)
-      middlewares.insert(index, middleware)
+      middlewares.insert(index, build_middleware(klass, args, block))
     end
 
     alias_method :insert_before, :insert
@@ -104,26 +75,46 @@ module ActionDispatch
     end
 
     def delete(target)
-      middlewares.delete target
+      target = get_class target
+      middlewares.delete_if { |m| m.klass == target }
     end
 
-    def use(*args, &block)
-      middleware = self.class::Middleware.new(*args, &block)
-      middlewares.push(middleware)
+    def use(klass, *args, &block)
+      middlewares.push(build_middleware(klass, args, block))
     end
 
-    def build(app = nil, &block)
-      app ||= block
-      raise "MiddlewareStack#build requires an app" unless app
+    def build(app = Proc.new)
       middlewares.freeze.reverse.inject(app) { |a, e| e.build(a) }
     end
 
-  protected
+    private
 
     def assert_index(index, where)
-      i = index.is_a?(Integer) ? index : middlewares.index(index)
+      index = get_class index
+      i = index.is_a?(Integer) ? index : middlewares.index { |m| m.klass == index }
       raise "No such middleware to insert #{where}: #{index.inspect}" unless i
       i
     end
+
+    def get_class(klass)
+      if klass.is_a?(String) || klass.is_a?(Symbol)
+        classcache = ActiveSupport::Dependencies::Reference
+        converted_klass = classcache[klass.to_s]
+        ActiveSupport::Deprecation.warn <<-eowarn
+Passing strings or symbols to the middleware builder is deprecated, please change
+them to actual class references.  For example:
+
+  "#{klass}" => #{converted_klass}
+
+        eowarn
+        converted_klass
+      else
+        klass
+      end
+    end
+
+    def build_middleware(klass, args, block)
+      Middleware.new(get_class(klass), args, block)
+    end
   end
 end
diff --git a/actionpack/lib/action_dispatch/middleware/static.rb b/actionpack/lib/action_dispatch/middleware/static.rb
index 002bf8b11a..75f8e05a3f 100644
--- a/actionpack/lib/action_dispatch/middleware/static.rb
+++ b/actionpack/lib/action_dispatch/middleware/static.rb
@@ -3,33 +3,38 @@ require 'active_support/core_ext/uri'
 
 module ActionDispatch
   # This middleware returns a file's contents from disk in the body response.
-  # When initialized it can accept an optional 'Cache-Control' header which
-  # will be set when a response containing a file's contents is delivered.
+  # When initialized, it can accept optional HTTP headers, which will be set
+  # when a response containing a file's contents is delivered.
   #
   # This middleware will render the file specified in `env["PATH_INFO"]`
-  # where the base path is in the +root+ directory. For example if the +root+
-  # is set to `public/` then a request with `env["PATH_INFO"]` of
-  # `assets/application.js` will return a response with contents of a file
+  # where the base path is in the +root+ directory. For example, if the +root+
+  # is set to `public/`, then a request with `env["PATH_INFO"]` of
+  # `assets/application.js` will return a response with the contents of a file
   # located at `public/assets/application.js` if the file exists. If the file
-  # does not exist a 404 "File not Found" response will be returned.
+  # does not exist, a 404 "File not Found" response will be returned.
   class FileHandler
-    def initialize(root, cache_control)
+    def initialize(root, index: 'index', headers: {})
       @root          = root.chomp('/')
       @compiled_root = /^#{Regexp.escape(root)}/
-      headers        = cache_control && { 'Cache-Control' => cache_control }
-      @file_server = ::Rack::File.new(@root, headers)
+      @file_server   = ::Rack::File.new(@root, headers)
+      @index         = index
     end
 
+    # Takes a path to a file. If the file is found, has valid encoding, and has
+    # correct read permissions, the return value is a URI-escaped string
+    # representing the filename. Otherwise, false is returned.
+    #
+    # Used by the `Static` class to check the existence of a valid file
+    # in the server's `public/` directory (see Static#call).
     def match?(path)
-      path = URI.parser.unescape(path)
+      path = ::Rack::Utils.unescape_path path
       return false unless path.valid_encoding?
+      path = Rack::Utils.clean_path_info path
 
-      paths = [path, "#{path}#{ext}", "#{path}/index#{ext}"].map { |v|
-        Rack::Utils.clean_path_info v
-      }
+      paths = [path, "#{path}#{ext}", "#{path}/#{@index}#{ext}"]
 
       if match = paths.detect { |p|
-        path = File.join(@root, p)
+        path = File.join(@root, p.force_encoding('UTF-8'.freeze))
         begin
           File.file?(path) && File.readable?(path)
         rescue SystemCallError
@@ -37,28 +42,35 @@ module ActionDispatch
         end
 
       }
-        return ::Rack::Utils.escape(match)
+        return ::Rack::Utils.escape_path(match)
       end
     end
 
     def call(env)
-      path      = env['PATH_INFO']
+      serve ActionDispatch::Request.new env
+    end
+
+    def serve(request)
+      path      = request.path_info
       gzip_path = gzip_file_path(path)
 
-      if gzip_path && gzip_encoding_accepted?(env)
-        env['PATH_INFO']            = gzip_path
-        status, headers, body       = @file_server.call(env)
+      if gzip_path && gzip_encoding_accepted?(request)
+        request.path_info           = gzip_path
+        status, headers, body       = @file_server.call(request.env)
+        if status == 304
+          return [status, headers, body]
+        end
         headers['Content-Encoding'] = 'gzip'
         headers['Content-Type']     = content_type(path)
       else
-        status, headers, body = @file_server.call(env)
+        status, headers, body = @file_server.call(request.env)
       end
 
       headers['Vary'] = 'Accept-Encoding' if gzip_path
 
       return [status, headers, body]
     ensure
-      env['PATH_INFO'] = path
+      request.path_info = path
     end
 
     private
@@ -67,17 +79,17 @@ module ActionDispatch
       end
 
       def content_type(path)
-        ::Rack::Mime.mime_type(::File.extname(path), 'text/plain')
+        ::Rack::Mime.mime_type(::File.extname(path), 'text/plain'.freeze)
       end
 
-      def gzip_encoding_accepted?(env)
-        env['HTTP_ACCEPT_ENCODING'] =~ /\bgzip\b/i
+      def gzip_encoding_accepted?(request)
+        request.accept_encoding =~ /\bgzip\b/i
       end
 
       def gzip_file_path(path)
         can_gzip_mime = content_type(path) =~ /\A(?:text\/|application\/javascript)/
         gzip_path     = "#{path}.gz"
-        if can_gzip_mime && File.exist?(File.join(@root, ::Rack::Utils.unescape(gzip_path)))
+        if can_gzip_mime && File.exist?(File.join(@root, ::Rack::Utils.unescape_path(gzip_path)))
           gzip_path
         else
           false
@@ -86,7 +98,7 @@ module ActionDispatch
   end
 
   # This middleware will attempt to return the contents of a file's body from
-  # disk in the response.  If a file is not found on disk, the request will be
+  # disk in the response. If a file is not found on disk, the request will be
   # delegated to the application stack. This middleware is commonly initialized
   # to serve assets from a server's `public/` directory.
   #
@@ -95,22 +107,30 @@ module ActionDispatch
   # produce a directory traversal using this middleware. Only 'GET' and 'HEAD'
   # requests will result in a file being returned.
   class Static
-    def initialize(app, path, cache_control=nil)
+    def initialize(app, path, deprecated_cache_control = :not_set, index: 'index', headers: {})
+      if deprecated_cache_control != :not_set
+        ActiveSupport::Deprecation.warn("The `cache_control` argument is deprecated," \
+                                        "replaced by `headers: { 'Cache-Control' => #{deprecated_cache_control} }`, " \
+                                        " and will be removed in Rails 5.1.")
+        headers['Cache-Control'.freeze] = deprecated_cache_control
+      end
+
       @app = app
-      @file_handler = FileHandler.new(path, cache_control)
+      @file_handler = FileHandler.new(path, index: index, headers: headers)
     end
 
     def call(env)
-      case env['REQUEST_METHOD']
-      when 'GET', 'HEAD'
-        path = env['PATH_INFO'].chomp('/')
+      req = ActionDispatch::Request.new env
+
+      if req.get? || req.head?
+        path = req.path_info.chomp('/'.freeze)
         if match = @file_handler.match?(path)
-          env["PATH_INFO"] = match
-          return @file_handler.call(env)
+          req.path_info = match
+          return @file_handler.serve(req)
         end
       end
 
-      @app.call(env)
+      @app.call(req.env)
     end
   end
 end
diff --git a/actionpack/lib/action_dispatch/middleware/templates/routes/_route.html.erb b/actionpack/lib/action_dispatch/middleware/templates/routes/_route.html.erb
index 24e44f31ac..6e995c85c1 100644
--- a/actionpack/lib/action_dispatch/middleware/templates/routes/_route.html.erb
+++ b/actionpack/lib/action_dispatch/middleware/templates/routes/_route.html.erb
@@ -4,13 +4,13 @@
       <%= route[:name] %><span class='helper'>_path</span>
     <% end %>
   </td>
-  <td data-route-verb='<%= route[:verb] %>'>
+  <td>
     <%= route[:verb] %>
   </td>
-  <td data-route-path='<%= route[:path] %>' data-regexp='<%= route[:regexp] %>'>
+  <td data-route-path='<%= route[:path] %>'>
     <%= route[:path] %>
   </td>
-  <td data-route-reqs='<%= route[:reqs] %>'>
-    <%= route[:reqs] %>
+  <td>
+    <%=simple_format route[:reqs] %>
   </td>
 </tr>
diff --git a/actionpack/lib/action_dispatch/middleware/templates/routes/_table.html.erb b/actionpack/lib/action_dispatch/middleware/templates/routes/_table.html.erb
index 5cee0b5932..429ea7057c 100644
--- a/actionpack/lib/action_dispatch/middleware/templates/routes/_table.html.erb
+++ b/actionpack/lib/action_dispatch/middleware/templates/routes/_table.html.erb
@@ -81,92 +81,87 @@
 </table>
 
 <script type='text/javascript'>
-  // Iterates each element through a function
-  function each(elems, func) {
-    if (!elems instanceof Array) { elems = [elems]; }
-    for (var i = 0, len = elems.length; i < len; i++) {
-      func(elems[i]);
-    }
-  }
-
-  // Sets innerHTML for an element
-  function setContent(elem, text) {
-    elem.innerHTML = text;
-  }
+  // support forEarch iterator on NodeList
+  NodeList.prototype.forEach = Array.prototype.forEach;
 
   // Enables path search functionality
   function setupMatchPaths() {
-    // Check if the user input (sanitized as a path) matches the regexp data attribute
-    function checkExactMatch(section, elem, value) {
-      var string = sanitizePath(value),
-          regexp = elem.getAttribute("data-regexp");
-
-      showMatch(string, regexp, section, elem);
+    // Check if there are any matched results in a section
+    function checkNoMatch(section, noMatchText) {
+      if (section.children.length <= 1) {
+        section.innerHTML += noMatchText;
+      }
     }
 
-    // Check if the route path data attribute contains the user input
-    function checkFuzzyMatch(section, elem, value) {
-      var string = elem.getAttribute("data-route-path"),
-          regexp = value;
-
-      showMatch(string, regexp, section, elem);
+    // get JSON from url and invoke callback with result
+    function getJSON(url, success) {
+      var xhr = new XMLHttpRequest();
+      xhr.open('GET', url);
+      xhr.onload = function() {
+        if (this.status == 200)
+          success(JSON.parse(this.response));
+      };
+      xhr.send();
     }
 
-    // Display the parent <tr> element in the appropriate section when there's a match
-    function showMatch(string, regexp, section, elem) {
-      if(string.match(RegExp(regexp))) {
-        section.appendChild(elem.parentNode.cloneNode(true));
+    function delayedKeyup(input, callback) {
+      var timeout;
+      input.onkeyup = function(){
+        if (timeout) clearTimeout(timeout);
+        timeout = setTimeout(callback, 300);
       }
     }
 
-    // Check if there are any matched results in a section
-    function checkNoMatch(section, defaultText, noMatchText) {
-      if (section.innerHTML === defaultText) {
-        setContent(section, defaultText + noMatchText);
-      }
-    }
-
-    // Ensure path always starts with a slash "/" and remove params or fragments
+    // remove params or fragments
     function sanitizePath(path) {
-      var path = path.charAt(0) == '/' ? path : "/" + path;
-      return path.replace(/\#.*|\?.*/, '');
+      return path.replace(/[#?].*/, '');
     }
 
-    var regexpElems     = document.querySelectorAll('#route_table [data-regexp]'),
-        searchElem      = document.querySelector('#search'),
-        exactMatches    = document.querySelector('#exact_matches'),
-        fuzzyMatches    = document.querySelector('#fuzzy_matches');
+    var pathElements = document.querySelectorAll('#route_table [data-route-path]'),
+        searchElem   = document.querySelector('#search'),
+        exactSection = document.querySelector('#exact_matches'),
+        fuzzySection = document.querySelector('#fuzzy_matches');
 
     // Remove matches when no search value is present
     searchElem.onblur = function(e) {
       if (searchElem.value === "") {
-        setContent(exactMatches, "");
-        setContent(fuzzyMatches, "");
+        exactSection.innerHTML = "";
+        fuzzySection.innerHTML = "";
       }
     }
 
     // On key press perform a search for matching paths
-    searchElem.onkeyup = function(e){
-      var userInput         = searchElem.value,
-          defaultExactMatch = '<tr><th colspan="4">Paths Matching (' + escape(sanitizePath(userInput)) +'):</th></tr>',
-          defaultFuzzyMatch = '<tr><th colspan="4">Paths Containing (' + escape(userInput) +'):</th></tr>',
+    delayedKeyup(searchElem, function() {
+      var path = sanitizePath(searchElem.value),
+          defaultExactMatch = '<tr><th colspan="4">Paths Matching (' + path +'):</th></tr>',
+          defaultFuzzyMatch = '<tr><th colspan="4">Paths Containing (' + path +'):</th></tr>',
           noExactMatch      = '<tr><th colspan="4">No Exact Matches Found</th></tr>',
           noFuzzyMatch      = '<tr><th colspan="4">No Fuzzy Matches Found</th></tr>';
 
-      // Clear out results section
-      setContent(exactMatches, defaultExactMatch);
-      setContent(fuzzyMatches, defaultFuzzyMatch);
+      if (!path)
+        return searchElem.onblur();
 
-      // Display exact matches and fuzzy matches
-      each(regexpElems, function(elem) {
-        checkExactMatch(exactMatches, elem, userInput);
-        checkFuzzyMatch(fuzzyMatches, elem, userInput);
-      })
+      getJSON('/rails/info/routes?path=' + path, function(matches){
+        // Clear out results section
+        exactSection.innerHTML = defaultExactMatch;
+        fuzzySection.innerHTML = defaultFuzzyMatch;
 
-      // Display 'No Matches' message when no matches are found
-      checkNoMatch(exactMatches, defaultExactMatch, noExactMatch);
-      checkNoMatch(fuzzyMatches, defaultFuzzyMatch, noFuzzyMatch);
-    }
+        // Display exact matches and fuzzy matches
+        pathElements.forEach(function(elem) {
+          var elemPath = elem.getAttribute('data-route-path');
+
+          if (matches['exact'].indexOf(elemPath) != -1)
+            exactSection.appendChild(elem.parentNode.cloneNode(true));
+
+          if (matches['fuzzy'].indexOf(elemPath) != -1)
+            fuzzySection.appendChild(elem.parentNode.cloneNode(true));
+        })
+
+        // Display 'No Matches' message when no matches are found
+        checkNoMatch(exactSection, noExactMatch);
+        checkNoMatch(fuzzySection, noFuzzyMatch);
+      })
+    })
   }
 
   // Enables functionality to toggle between `_path` and `_url` helper suffixes
@@ -174,19 +169,20 @@
 
     // Sets content for each element
     function setValOn(elems, val) {
-      each(elems, function(elem) {
-        setContent(elem, val);
+      elems.forEach(function(elem) {
+        elem.innerHTML = val;
       });
     }
 
     // Sets onClick event for each element
     function onClick(elems, func) {
-      each(elems, function(elem) {
+      elems.forEach(function(elem) {
         elem.onclick = func;
       });
     }
 
     var toggleLinks = document.querySelectorAll('#route_table [data-route-helper]');
+
     onClick(toggleLinks, function(){
       var helperTxt   = this.getAttribute("data-route-helper"),
           helperElems = document.querySelectorAll('[data-route-name] span.helper');
diff --git a/actionpack/lib/action_dispatch/request/session.rb b/actionpack/lib/action_dispatch/request/session.rb
index 973627f106..9e7fcbd849 100644
--- a/actionpack/lib/action_dispatch/request/session.rb
+++ b/actionpack/lib/action_dispatch/request/session.rb
@@ -1,56 +1,56 @@
 require 'rack/session/abstract/id'
 
 module ActionDispatch
-  class Request < Rack::Request
+  class Request
     # Session is responsible for lazily loading the session from store.
     class Session # :nodoc:
-      ENV_SESSION_KEY         = Rack::Session::Abstract::ENV_SESSION_KEY # :nodoc:
-      ENV_SESSION_OPTIONS_KEY = Rack::Session::Abstract::ENV_SESSION_OPTIONS_KEY # :nodoc:
+      ENV_SESSION_KEY         = Rack::RACK_SESSION # :nodoc:
+      ENV_SESSION_OPTIONS_KEY = Rack::RACK_SESSION_OPTIONS # :nodoc:
 
       # Singleton object used to determine if an optional param wasn't specified
       Unspecified = Object.new
-
-      def self.create(store, env, default_options)
-        session_was = find env
-        session     = Request::Session.new(store, env)
+      
+      # Creates a session hash, merging the properties of the previous session if any
+      def self.create(store, req, default_options)
+        session_was = find req
+        session     = Request::Session.new(store, req)
         session.merge! session_was if session_was
 
-        set(env, session)
-        Options.set(env, Request::Session::Options.new(store, env, default_options))
+        set(req, session)
+        Options.set(req, Request::Session::Options.new(store, default_options))
         session
       end
 
-      def self.find(env)
-        env[ENV_SESSION_KEY]
+      def self.find(req)
+        req.get_header ENV_SESSION_KEY
       end
 
-      def self.set(env, session)
-        env[ENV_SESSION_KEY] = session
+      def self.set(req, session)
+        req.set_header ENV_SESSION_KEY, session
       end
 
       class Options #:nodoc:
-        def self.set(env, options)
-          env[ENV_SESSION_OPTIONS_KEY] = options
+        def self.set(req, options)
+          req.set_header ENV_SESSION_OPTIONS_KEY, options
         end
 
-        def self.find(env)
-          env[ENV_SESSION_OPTIONS_KEY]
+        def self.find(req)
+          req.get_header ENV_SESSION_OPTIONS_KEY
         end
 
-        def initialize(by, env, default_options)
+        def initialize(by, default_options)
           @by       = by
-          @env      = env
           @delegate = default_options.dup
         end
 
         def [](key)
-          if key == :id
-            @delegate.fetch(key) {
-              @delegate[:id] = @by.send(:extract_session_id, @env)
-            }
-          else
-            @delegate[key]
-          end
+          @delegate[key]
+        end
+
+        def id(req)
+          @delegate.fetch(:id) {
+            @by.send(:extract_session_id, req)
+          }
         end
 
         def []=(k,v);         @delegate[k] = v; end
@@ -58,38 +58,40 @@ module ActionDispatch
         def values_at(*args); @delegate.values_at(*args); end
       end
 
-      def initialize(by, env)
+      def initialize(by, req)
         @by       = by
-        @env      = env
+        @req      = req
         @delegate = {}
         @loaded   = false
         @exists   = nil # we haven't checked yet
       end
 
       def id
-        options[:id]
+        options.id(@req)
       end
 
       def options
-        Options.find @env
+        Options.find @req
       end
 
       def destroy
         clear
         options = self.options || {}
-        new_sid = @by.send(:destroy_session, @env, options[:id], options)
-        options[:id] = new_sid # Reset session id with a new value or nil
+        @by.send(:delete_session, @req, options.id(@req), options)
 
         # Load the new sid to be written with the response
         @loaded = false
         load_for_write!
       end
 
+      # Returns value of the key stored in the session or
+      # nil if the given key is not found in the session.
       def [](key)
         load_for_read!
         @delegate[key.to_s]
       end
 
+      # Returns true if the session has the given key or false.
       def has_key?(key)
         load_for_read!
         @delegate.key?(key.to_s)
@@ -97,39 +99,69 @@ module ActionDispatch
       alias :key? :has_key?
       alias :include? :has_key?
 
+      # Returns keys of the session as Array.
       def keys
         @delegate.keys
       end
 
+      # Returns values of the session as Array.
       def values
         @delegate.values
       end
 
+      # Writes given value to given key of the session.
       def []=(key, value)
         load_for_write!
         @delegate[key.to_s] = value
       end
 
+      # Clears the session.
       def clear
         load_for_write!
         @delegate.clear
       end
 
+      # Returns the session as Hash.
       def to_hash
         load_for_read!
         @delegate.dup.delete_if { |_,v| v.nil? }
       end
 
+      # Updates the session with given Hash.
+      #
+      #   session.to_hash
+      #   # => {"session_id"=>"e29b9ea315edf98aad94cc78c34cc9b2"}
+      #
+      #   session.update({ "foo" => "bar" })
+      #   # => {"session_id"=>"e29b9ea315edf98aad94cc78c34cc9b2", "foo" => "bar"}
+      #
+      #   session.to_hash
+      #   # => {"session_id"=>"e29b9ea315edf98aad94cc78c34cc9b2", "foo" => "bar"}
       def update(hash)
         load_for_write!
         @delegate.update stringify_keys(hash)
       end
 
+      # Deletes given key from the session.
       def delete(key)
         load_for_write!
         @delegate.delete key.to_s
       end
 
+      # Returns value of given key from the session, or raises +KeyError+
+      # if can't find given key in case of not setted dafault value.
+      # Returns default value if specified.
+      #
+      #   session.fetch(:foo)
+      #   # => KeyError: key not found: "foo"
+      #
+      #   session.fetch(:foo, :bar)
+      #   # => :bar
+      #
+      #   session.fetch(:foo) do
+      #     :bar
+      #   end
+      #   # => :bar
       def fetch(key, default=Unspecified, &block)
         load_for_read!
         if default == Unspecified
@@ -149,7 +181,7 @@ module ActionDispatch
 
       def exists?
         return @exists unless @exists.nil?
-        @exists = @by.send(:session_exists?, @env)
+        @exists = @by.send(:session_exists?, @req)
       end
 
       def loaded?
@@ -177,7 +209,7 @@ module ActionDispatch
       end
 
       def load!
-        id, session = @by.load_session @env
+        id, session = @by.load_session @req
         options[:id] = id
         @delegate.replace(stringify_keys(session))
         @loaded = true
diff --git a/actionpack/lib/action_dispatch/request/utils.rb b/actionpack/lib/action_dispatch/request/utils.rb
index 1c9371d89c..bb3df3c311 100644
--- a/actionpack/lib/action_dispatch/request/utils.rb
+++ b/actionpack/lib/action_dispatch/request/utils.rb
@@ -1,28 +1,64 @@
 module ActionDispatch
-  class Request < Rack::Request
+  class Request
     class Utils # :nodoc:
 
       mattr_accessor :perform_deep_munge
       self.perform_deep_munge = true
 
-      class << self
-        # Remove nils from the params hash
-        def deep_munge(hash, keys = [])
-          return hash unless perform_deep_munge
+      def self.normalize_encode_params(params)
+        if perform_deep_munge
+          NoNilParamEncoder.normalize_encode_params params
+        else
+          ParamEncoder.normalize_encode_params params
+        end
+      end
+
+      def self.check_param_encoding(params)
+        case params
+        when Array
+          params.each { |element| check_param_encoding(element) }
+        when Hash
+          params.each_value { |value| check_param_encoding(value) }
+        when String
+          unless params.valid_encoding?
+            # Raise Rack::Utils::InvalidParameterError for consistency with Rack.
+            # ActionDispatch::Request#GET will re-raise as a BadRequest error.
+            raise Rack::Utils::InvalidParameterError, "Non UTF-8 value: #{params}"
+          end
+        end
+      end
 
-          hash.each do |k, v|
-            keys << k
-            case v
-            when Array
-              v.grep(Hash) { |x| deep_munge(x, keys) }
-              v.compact!
-            when Hash
-              deep_munge(v, keys)
+      class ParamEncoder # :nodoc:
+        # Convert nested Hash to HashWithIndifferentAccess.
+        #
+        def self.normalize_encode_params(params)
+          case params
+          when Array
+            handle_array params
+          when Hash
+            if params.has_key?(:tempfile)
+              ActionDispatch::Http::UploadedFile.new(params)
+            else
+              params.each_with_object({}) do |(key, val), new_hash|
+                new_hash[key] = normalize_encode_params(val)
+              end.with_indifferent_access
             end
-            keys.pop
+          else
+            params
           end
+        end
+
+        def self.handle_array(params)
+          params.map! { |el| normalize_encode_params(el) }
+        end
+      end
 
-          hash
+      # Remove nils from the params hash
+      class NoNilParamEncoder < ParamEncoder # :nodoc:
+        def self.handle_array(params)
+          list = super
+          list.compact!
+          list
         end
       end
     end
diff --git a/actionpack/lib/action_dispatch/routing.rb b/actionpack/lib/action_dispatch/routing.rb
index ce03164ca9..59c3f9248f 100644
--- a/actionpack/lib/action_dispatch/routing.rb
+++ b/actionpack/lib/action_dispatch/routing.rb
@@ -1,8 +1,3 @@
-# encoding: UTF-8
-require 'active_support/core_ext/object/to_param'
-require 'active_support/core_ext/regexp'
-require 'active_support/dependencies/autoload'
-
 module ActionDispatch
   # The routing module provides URL rewriting in native Ruby. It's a way to
   # redirect incoming requests to controllers and actions. This replaces
@@ -58,7 +53,7 @@ module ActionDispatch
   #     resources :posts, :comments
   #   end
   #
-  # Alternately, you can add prefixes to your path without using a separate
+  # Alternatively, you can add prefixes to your path without using a separate
   # directory by using +scope+. +scope+ takes additional options which
   # apply to all enclosed routes.
   #
@@ -151,6 +146,7 @@ module ActionDispatch
   #     get 'geocode/:postalcode' => :show, constraints: {
   #       postalcode: /\d{5}(-\d{4})?/
   #     }
+  #   end
   #
   # Constraints can include the 'ignorecase' and 'extended syntax' regular
   # expression modifiers:
@@ -232,7 +228,6 @@ module ActionDispatch
   #   def send_to_jail
   #     get '/jail'
   #     assert_response :success
-  #     assert_template "jail/front"
   #   end
   #
   #   def goes_to_login
diff --git a/actionpack/lib/action_dispatch/routing/inspector.rb b/actionpack/lib/action_dispatch/routing/inspector.rb
index df5ebb6751..f3a5268d2e 100644
--- a/actionpack/lib/action_dispatch/routing/inspector.rb
+++ b/actionpack/lib/action_dispatch/routing/inspector.rb
@@ -16,10 +16,6 @@ module ActionDispatch
         app.app
       end
 
-      def verb
-        super.source.gsub(/[$^]/, '')
-      end
-
       def path
         super.spec.to_s
       end
@@ -28,23 +24,6 @@ module ActionDispatch
         super.to_s
       end
 
-      def regexp
-        __getobj__.path.to_regexp
-      end
-
-      def json_regexp
-        str = regexp.inspect.
-              sub('\\A' , '^').
-              sub('\\Z' , '$').
-              sub('\\z' , '$').
-              sub(/^\// , '').
-              sub(/\/[a-z]*$/ , '').
-              gsub(/\(\?#.+\)/ , '').
-              gsub(/\(\?-\w+:/ , '(').
-              gsub(/\s/ , '')
-        Regexp.new(str).source
-      end
-
       def reqs
         @reqs ||= begin
           reqs = endpoint
@@ -62,7 +41,7 @@ module ActionDispatch
       end
 
       def internal?
-        controller.to_s =~ %r{\Arails/(info|mailers|welcome)} || path =~ %r{\A#{Rails.application.config.assets.prefix}\z}
+        controller.to_s =~ %r{\Arails/(info|mailers|welcome)}
       end
 
       def engine?
@@ -117,11 +96,10 @@ module ActionDispatch
         end.reject(&:internal?).collect do |route|
           collect_engine_routes(route)
 
-          { name:   route.name,
-            verb:   route.verb,
-            path:   route.path,
-            reqs:   route.reqs,
-            regexp: route.json_regexp }
+          { name: route.name,
+            verb: route.verb,
+            path: route.path,
+            reqs: route.reqs }
         end
       end
 
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 8b04dfaa45..7c0404ca62 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -1,10 +1,8 @@
-require 'active_support/core_ext/hash/except'
 require 'active_support/core_ext/hash/reverse_merge'
 require 'active_support/core_ext/hash/slice'
 require 'active_support/core_ext/enumerable'
 require 'active_support/core_ext/array/extract_options'
-require 'active_support/core_ext/module/remove_method'
-require 'active_support/inflector'
+require 'active_support/core_ext/regexp'
 require 'action_dispatch/routing/redirection'
 require 'action_dispatch/routing/endpoint'
 
@@ -16,7 +14,10 @@ module ActionDispatch
       class Constraints < Endpoint #:nodoc:
         attr_reader :app, :constraints
 
-        def initialize(app, constraints, dispatcher_p)
+        SERVE = ->(app, req) { app.serve req }
+        CALL  = ->(app, req) { app.call req.env }
+
+        def initialize(app, constraints, strategy)
           # Unwrap Constraints objects.  I don't actually think it's possible
           # to pass a Constraints object to this constructor, but there were
           # multiple places that kept testing children of this object.  I
@@ -26,12 +27,12 @@ module ActionDispatch
             app = app.app
           end
 
-          @dispatcher = dispatcher_p
+          @strategy = strategy
 
           @app, @constraints, = app, constraints
         end
 
-        def dispatcher?; @dispatcher; end
+        def dispatcher?; @strategy == SERVE; end
 
         def matches?(req)
           @constraints.all? do |constraint|
@@ -43,11 +44,7 @@ module ActionDispatch
         def serve(req)
           return [ 404, {'X-Cascade' => 'pass'}, [] ] unless matches?(req)
 
-          if dispatcher?
-            @app.serve req
-          else
-            @app.call req.env
-          end
+          @strategy.call @app, req
         end
 
         private
@@ -59,101 +56,168 @@ module ActionDispatch
       class Mapping #:nodoc:
         ANCHOR_CHARACTERS_REGEX = %r{\A(\\A|\^)|(\\Z|\\z|\$)\Z}
 
-        attr_reader :requirements, :conditions, :defaults
-        attr_reader :to, :default_controller, :default_action, :as, :anchor
+        attr_reader :requirements, :defaults
+        attr_reader :to, :default_controller, :default_action
+        attr_reader :required_defaults, :ast
 
-        def self.build(scope, set, path, as, options)
+        def self.build(scope, set, ast, controller, default_action, to, via, formatted, options_constraints, anchor, options)
           options = scope[:options].merge(options) if scope[:options]
 
-          options.delete :only
-          options.delete :except
-          options.delete :shallow_path
-          options.delete :shallow_prefix
-          options.delete :shallow
+          defaults = (scope[:defaults] || {}).dup
+          scope_constraints = scope[:constraints] || {}
 
-          defaults = (scope[:defaults] || {}).merge options.delete(:defaults) || {}
+          new set, ast, defaults, controller, default_action, scope[:module], to, formatted, scope_constraints, scope[:blocks] || [], via, options_constraints, anchor, options
+        end
 
-          new scope, set, path, defaults, as, options
+        def self.check_via(via)
+          if via.empty?
+            msg = "You should not use the `match` method in your router without specifying an HTTP method.\n" \
+              "If you want to expose your action to both GET and POST, add `via: [:get, :post]` option.\n" \
+              "If you want to expose your action to GET, use `get` in the router:\n" \
+              "  Instead of: match \"controller#action\"\n" \
+              "  Do: get \"controller#action\""
+            raise ArgumentError, msg
+          end
+          via
         end
 
-        def initialize(scope, set, path, defaults, as, options)
-          @requirements, @conditions = {}, {}
-          @defaults = defaults
-          @set = set
+        def self.normalize_path(path, format)
+          path = Mapper.normalize_path(path)
 
-          @to                 = options.delete :to
-          @default_controller = options.delete(:controller) || scope[:controller]
-          @default_action     = options.delete(:action) || scope[:action]
-          @as                 = as
-          @anchor             = options.delete :anchor
+          if format == true
+            "#{path}.:format"
+          elsif optional_format?(path, format)
+            "#{path}(.:format)"
+          else
+            path
+          end
+        end
 
-          formatted = options.delete :format
-          via = Array(options.delete(:via) { [] })
-          options_constraints = options.delete :constraints
+        def self.optional_format?(path, format)
+          format != false && !path.include?(':format') && !path.end_with?('/')
+        end
 
-          path = normalize_path! path, formatted
-          ast  = path_ast path
-          path_params = path_params ast
+        def initialize(set, ast, defaults, controller, default_action, modyoule, to, formatted, scope_constraints, blocks, via, options_constraints, anchor, options)
+          @defaults = defaults
+          @set = set
+
+          @to                 = to
+          @default_controller = controller
+          @default_action     = default_action
+          @ast                = ast
+          @anchor             = anchor
+          @via                = via
 
-          options = normalize_options!(options, formatted, path_params, ast, scope[:module])
+          path_params = ast.find_all(&:symbol?).map(&:to_sym)
 
+          options = add_wildcard_options(options, formatted, ast)
 
-          split_constraints(path_params, scope[:constraints]) if scope[:constraints]
-          constraints = constraints(options, path_params)
+          options = normalize_options!(options, path_params, modyoule)
 
-          split_constraints path_params, constraints
+          split_options = constraints(options, path_params)
 
-          @blocks = blocks(options_constraints, scope[:blocks])
+          constraints = scope_constraints.merge Hash[split_options[:constraints] || []]
 
           if options_constraints.is_a?(Hash)
-            split_constraints path_params, options_constraints
-            options_constraints.each do |key, default|
-              if URL_OPTIONS.include?(key) && (String === default || Fixnum === default)
-                @defaults[key] ||= default
-              end
-            end
+            @defaults = Hash[options_constraints.find_all { |key, default|
+              URL_OPTIONS.include?(key) && (String === default || Fixnum === default)
+            }].merge @defaults
+            @blocks = blocks
+            constraints.merge! options_constraints
+          else
+            @blocks = blocks(options_constraints)
           end
 
-          normalize_format!(formatted)
+          requirements, conditions = split_constraints path_params, constraints
+          verify_regexp_requirements requirements.map(&:last).grep(Regexp)
+
+          formats = normalize_format(formatted)
 
-          @conditions[:path_info] = path
-          @conditions[:parsed_path_info] = ast
+          @requirements = formats[:requirements].merge Hash[requirements]
+          @conditions = Hash[conditions]
+          @defaults = formats[:defaults].merge(@defaults).merge(normalize_defaults(options))
 
-          add_request_method(via, @conditions)
-          normalize_defaults!(options)
+          @required_defaults = (split_options[:required_defaults] || []).map(&:first)
         end
 
-        def to_route
-          [ app(@blocks), conditions, requirements, defaults, as, anchor ]
+        def make_route(name, precedence)
+          route = Journey::Route.new(name,
+                            application,
+                            path,
+                            conditions,
+                            required_defaults,
+                            defaults,
+                            request_method,
+                            precedence)
+
+          route
         end
 
-        private
+        def application
+          app(@blocks)
+        end
+
+        def path
+          build_path @ast, requirements, @anchor
+        end
 
-          def normalize_path!(path, format)
-            path = Mapper.normalize_path(path)
+        def conditions
+          build_conditions @conditions, @set.request_class
+        end
 
-            if format == true
-              "#{path}.:format"
-            elsif optional_format?(path, format)
-              "#{path}(.:format)"
-            else
-              path
-            end
-          end
+        def build_conditions(current_conditions, request_class)
+          conditions = current_conditions.dup
 
-          def optional_format?(path, format)
-            format != false && !path.include?(':format') && !path.end_with?('/')
+          conditions.keep_if do |k, _|
+            request_class.public_method_defined?(k)
           end
+        end
+        private :build_conditions
+
+        def request_method
+          @via.map { |x| Journey::Route.verb_matcher(x) }
+        end
+        private :request_method
+
+        JOINED_SEPARATORS = SEPARATORS.join # :nodoc:
+
+        def build_path(ast, requirements, anchor)
+          pattern = Journey::Path::Pattern.new(ast, requirements, JOINED_SEPARATORS, anchor)
+
+          # Get all the symbol nodes followed by literals that are not the
+          # dummy node.
+          symbols = ast.find_all { |n|
+            n.cat? && n.left.symbol? && n.right.cat? && n.right.left.literal?
+          }.map(&:left)
 
-          def normalize_options!(options, formatted, path_params, path_ast, modyoule)
+          # Get all the symbol nodes preceded by literals.
+          symbols.concat ast.find_all { |n|
+            n.cat? && n.left.literal? && n.right.cat? && n.right.left.symbol?
+          }.map { |n| n.right.left }
+
+          symbols.each { |x|
+            x.regexp = /(?:#{Regexp.union(x.regexp, '-')})+/
+          }
+
+          pattern
+        end
+        private :build_path
+
+
+        private
+          def add_wildcard_options(options, formatted, path_ast)
             # Add a constraint for wildcard route to make it non-greedy and match the
             # optional format part of the route by default
             if formatted != false
-              path_ast.grep(Journey::Nodes::Star) do |node|
-                options[node.name.to_sym] ||= /.+?/
-              end
+              path_ast.grep(Journey::Nodes::Star).each_with_object({}) { |node, hash|
+                hash[node.name.to_sym] ||= /.+?/
+              }.merge options
+            else
+              options
             end
+          end
 
+          def normalize_options!(options, path_params, modyoule)
             if path_params.include?(:controller)
               raise ArgumentError, ":controller segment is not allowed within a namespace block" if modyoule
 
@@ -178,74 +242,54 @@ module ActionDispatch
           end
 
           def split_constraints(path_params, constraints)
-            constraints.each_pair do |key, requirement|
-              if path_params.include?(key) || key == :controller
-                verify_regexp_requirement(requirement) if requirement.is_a?(Regexp)
-                @requirements[key] = requirement
-              else
-                @conditions[key] = requirement
-              end
-            end
-          end
-
-          def normalize_format!(formatted)
-            if formatted == true
-              @requirements[:format] ||= /.+/
-            elsif Regexp === formatted
-              @requirements[:format] = formatted
-              @defaults[:format] = nil
-            elsif String === formatted
-              @requirements[:format] = Regexp.compile(formatted)
-              @defaults[:format] = formatted
+            constraints.partition do |key, requirement|
+              path_params.include?(key) || key == :controller
             end
           end
 
-          def verify_regexp_requirement(requirement)
-            if requirement.source =~ ANCHOR_CHARACTERS_REGEX
-              raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
-            end
-
-            if requirement.multiline?
-              raise ArgumentError, "Regexp multiline option is not allowed in routing requirements: #{requirement.inspect}"
+          def normalize_format(formatted)
+            case formatted
+            when true
+              { requirements: { format: /.+/ },
+                defaults:     {} }
+            when Regexp
+              { requirements: { format: formatted },
+                defaults:     { format: nil } }
+            when String
+              { requirements: { format: Regexp.compile(formatted) },
+                defaults:     { format: formatted } }
+            else
+              { requirements: { }, defaults: { } }
             end
           end
 
-          def normalize_defaults!(options)
-            options.each_pair do |key, default|
-              unless Regexp === default
-                @defaults[key] = default
+          def verify_regexp_requirements(requirements)
+            requirements.each do |requirement|
+              if requirement.source =~ ANCHOR_CHARACTERS_REGEX
+                raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
               end
-            end
-          end
 
-          def verify_callable_constraint(callable_constraint)
-            unless callable_constraint.respond_to?(:call) || callable_constraint.respond_to?(:matches?)
-              raise ArgumentError, "Invalid constraint: #{callable_constraint.inspect} must respond to :call or :matches?"
+              if requirement.multiline?
+                raise ArgumentError, "Regexp multiline option is not allowed in routing requirements: #{requirement.inspect}"
+              end
             end
           end
 
-          def add_request_method(via, conditions)
-            return if via == [:all]
-
-            if via.empty?
-              msg = "You should not use the `match` method in your router without specifying an HTTP method.\n" \
-                    "If you want to expose your action to both GET and POST, add `via: [:get, :post]` option.\n" \
-                    "If you want to expose your action to GET, use `get` in the router:\n" \
-                    "  Instead of: match \"controller#action\"\n" \
-                    "  Do: get \"controller#action\""
-              raise ArgumentError, msg
-            end
-
-            conditions[:request_method] = via.map { |m| m.to_s.dasherize.upcase }
+          def normalize_defaults(options)
+            Hash[options.reject { |_, default| Regexp === default }]
           end
 
           def app(blocks)
-            if to.respond_to?(:call)
-              Constraints.new(to, blocks, false)
-            elsif blocks.any?
-              Constraints.new(dispatcher(defaults), blocks, true)
+            if to.is_a?(Class) && to < ActionController::Metal
+              Routing::RouteSet::StaticDispatcher.new to
             else
-              dispatcher(defaults)
+              if to.respond_to?(:call)
+                Constraints.new(to, blocks, Constraints::CALL)
+              elsif blocks.any?
+                Constraints.new(dispatcher(defaults.key?(:controller)), blocks, Constraints::SERVE)
+              else
+                dispatcher(defaults.key?(:controller))
+              end
             end
           end
 
@@ -303,40 +347,29 @@ module ActionDispatch
             yield
           end
 
-          def blocks(options_constraints, scope_blocks)
-            if options_constraints && !options_constraints.is_a?(Hash)
-              verify_callable_constraint(options_constraints)
-              [options_constraints]
-            else
-              scope_blocks || []
+          def blocks(callable_constraint)
+            unless callable_constraint.respond_to?(:call) || callable_constraint.respond_to?(:matches?)
+              raise ArgumentError, "Invalid constraint: #{callable_constraint.inspect} must respond to :call or :matches?"
             end
+            [callable_constraint]
           end
 
           def constraints(options, path_params)
-            constraints = {}
-            required_defaults = []
-            options.each_pair do |key, option|
+            options.group_by do |key, option|
               if Regexp === option
-                constraints[key] = option
+                :constraints
               else
-                required_defaults << key unless path_params.include?(key)
+                if path_params.include?(key)
+                  :path_params
+                else
+                  :required_defaults
+                end
               end
             end
-            @conditions[:required_defaults] = required_defaults
-            constraints
-          end
-
-          def path_params(ast)
-            ast.grep(Journey::Nodes::Symbol).map { |n| n.name.to_sym }
-          end
-
-          def path_ast(path)
-            parser = Journey::Parser.new
-            parser.parse path
           end
 
-          def dispatcher(defaults)
-            @set.dispatcher defaults
+          def dispatcher(raise_on_name_error)
+            Routing::RouteSet::Dispatcher.new raise_on_name_error
           end
       end
 
@@ -368,7 +401,8 @@ module ActionDispatch
         # because this means it will be matched first. As this is the most popular route
         # of most Rails applications, this is beneficial.
         def root(options = {})
-          match '/', { :as => :root, :via => :get }.merge!(options)
+          name = has_named_route?(:root) ? nil : :root
+          match '/', { as: name, via:  :get }.merge!(options)
         end
 
         # Matches a url pattern to one or more routes.
@@ -418,7 +452,7 @@ module ActionDispatch
         # A pattern can also point to a +Rack+ endpoint i.e. anything that
         # responds to +call+:
         #
-        #   match 'photos/:id', to: lambda {|hash| [200, {}, ["Coming soon"]] }, via: :get
+        #   match 'photos/:id', to: -> (hash) { [200, {}, ["Coming soon"]] }, via: :get
         #   match 'photos/:id', to: PhotoRackApp, via: :get
         #   # Yes, controller actions are just rack endpoints
         #   match 'photos/:id', to: PhotosController.action(:show), via: :get
@@ -443,6 +477,21 @@ module ActionDispatch
         #   dynamic segment used to generate the routes).
         #   You can access that segment from your controller using
         #   <tt>params[<:param>]</tt>.
+        #   In your router:
+        #
+        #      resources :user, param: :name
+        #
+        #   You can override <tt>ActiveRecord::Base#to_param</tt> of a related
+        #   model to construct a URL:
+        #
+        #      class User < ActiveRecord::Base
+        #        def to_param
+        #          name
+        #        end
+        #      end
+        #
+        #   user = User.find_by(name: 'Phusion')
+        #   user_path(user)  # => "/users/Phusion"
         #
         # [:path]
         #   The path prefix for the routes.
@@ -470,7 +519,7 @@ module ActionDispatch
         #   +call+ or a string representing a controller's action.
         #
         #      match 'path', to: 'controller#action', via: :get
-        #      match 'path', to: lambda { |env| [200, {}, ["Success!"]] }, via: :get
+        #      match 'path', to: -> (env) { [200, {}, ["Success!"]] }, via: :get
         #      match 'path', to: RackApp, via: :get
         #
         # [:on]
@@ -588,7 +637,7 @@ module ActionDispatch
 
         # Query if the following named route was already defined.
         def has_named_route?(name)
-          @set.named_routes.routes[name.to_sym]
+          @set.named_routes.key? name
         end
 
         private
@@ -616,6 +665,7 @@ module ActionDispatch
                   super(options)
                 else
                   prefix_options = options.slice(*_route.segment_keys)
+                  prefix_options[:relative_url_root] = ''.freeze
                   # we must actually delete prefix segment keys to avoid passing them to next url_for
                   _route.segment_keys.each { |k| options.delete(k) }
                   _routes.url_helpers.send("#{name}_path", prefix_options)
@@ -670,7 +720,11 @@ module ActionDispatch
           def map_method(method, args, &block)
             options = args.extract_options!
             options[:via] = method
-            match(*args, options, &block)
+            if options.key?(:defaults)
+              defaults(options.delete(:defaults)) { match(*args, options, &block) }
+            else
+              match(*args, options, &block)
+            end
             self
           end
       end
@@ -773,8 +827,8 @@ module ActionDispatch
           end
 
           if options[:constraints].is_a?(Hash)
-            defaults = options[:constraints].select do
-              |k, v| URL_OPTIONS.include?(k) && (v.is_a?(String) || v.is_a?(Fixnum))
+            defaults = options[:constraints].select do |k, v|
+              URL_OPTIONS.include?(k) && (v.is_a?(String) || v.is_a?(Fixnum))
             end
 
             (options[:defaults] ||= {}).reverse_merge!(defaults)
@@ -782,16 +836,25 @@ module ActionDispatch
             block, options[:constraints] = options[:constraints], {}
           end
 
+          if options.key?(:only) || options.key?(:except)
+            scope[:action_options] = { only: options.delete(:only),
+                                       except: options.delete(:except) }
+          end
+
+          if options.key? :anchor
+            raise ArgumentError, 'anchor is ignored unless passed to `match`'
+          end
+
           @scope.options.each do |option|
             if option == :blocks
               value = block
             elsif option == :options
               value = options
             else
-              value = options.delete(option)
+              value = options.delete(option) { POISON }
             end
 
-            if value
+            unless POISON == value
               scope[option] = send("merge_#{option}_scope", @scope[option], value)
             end
           end
@@ -803,14 +866,18 @@ module ActionDispatch
           @scope = @scope.parent
         end
 
+        POISON = Object.new # :nodoc:
+
         # Scopes routes to a specific controller
         #
         #   controller "food" do
-        #     match "bacon", action: "bacon"
+        #     match "bacon", action: :bacon, via: :get
         #   end
-        def controller(controller, options={})
-          options[:controller] = controller
-          scope(options) { yield }
+        def controller(controller)
+          @scope = @scope.new(controller: controller)
+          yield
+        ensure
+          @scope = @scope.parent
         end
 
         # Scopes routes to a specific namespace. For example:
@@ -856,13 +923,14 @@ module ActionDispatch
 
           defaults = {
             module:         path,
-            path:           options.fetch(:path, path),
             as:             options.fetch(:as, path),
             shallow_path:   options.fetch(:path, path),
             shallow_prefix: options.fetch(:as, path)
           }
 
-          scope(defaults.merge!(options)) { yield }
+          path_scope(options.delete(:path) { path }) do
+            scope(defaults.merge!(options)) { yield }
+          end
         end
 
         # === Parameter Restriction
@@ -899,7 +967,7 @@ module ActionDispatch
         #
         # Requests to routes can be constrained based on specific criteria:
         #
-        #    constraints(lambda { |req| req.env["HTTP_USER_AGENT"] =~ /iPhone/ }) do
+        #    constraints(-> (req) { req.env["HTTP_USER_AGENT"] =~ /iPhone/ }) do
         #      resources :iphones
         #    end
         #
@@ -930,7 +998,10 @@ module ActionDispatch
         #   end
         # Using this, the +:id+ parameter here will default to 'home'.
         def defaults(defaults = {})
-          scope(:defaults => defaults) { yield }
+          @scope = @scope.new(defaults: merge_defaults_scope(@scope[:defaults], defaults))
+          yield
+        ensure
+          @scope = @scope.parent
         end
 
         private
@@ -962,6 +1033,14 @@ module ActionDispatch
             child
           end
 
+          def merge_via_scope(parent, child) #:nodoc:
+            child
+          end
+
+          def merge_format_scope(parent, child) #:nodoc:
+            child
+          end
+
           def merge_path_names_scope(parent, child) #:nodoc:
             merge_options_scope(parent, child)
           end
@@ -981,16 +1060,12 @@ module ActionDispatch
           end
 
           def merge_options_scope(parent, child) #:nodoc:
-            (parent || {}).except(*override_keys(child)).merge!(child)
+            (parent || {}).merge(child)
           end
 
           def merge_shallow_scope(parent, child) #:nodoc:
             child ? true : false
           end
-
-          def override_keys(child) #:nodoc:
-            child.key?(:only) || child.key?(:except) ? [:only, :except] : []
-          end
       end
 
       # Resource routing allows you to quickly declare all of the common routes
@@ -1040,27 +1115,34 @@ module ActionDispatch
         CANONICAL_ACTIONS = %w(index create new show update destroy)
 
         class Resource #:nodoc:
-          attr_reader :controller, :path, :options, :param
+          attr_reader :controller, :path, :param
 
-          def initialize(entities, options = {})
+          def initialize(entities, api_only, shallow, options = {})
             @name       = entities.to_s
             @path       = (options[:path] || @name).to_s
             @controller = (options[:controller] || @name).to_s
             @as         = options[:as]
             @param      = (options[:param] || :id).to_sym
             @options    = options
-            @shallow    = false
+            @shallow    = shallow
+            @api_only   = api_only
+            @only       = options.delete :only
+            @except     = options.delete :except
           end
 
           def default_actions
-            [:index, :create, :new, :show, :update, :destroy, :edit]
+            if @api_only
+              [:index, :create, :show, :update, :destroy]
+            else
+              [:index, :create, :new, :show, :update, :destroy, :edit]
+            end
           end
 
           def actions
-            if only = @options[:only]
-              Array(only).map(&:to_sym)
-            elsif except = @options[:except]
-              default_actions - Array(except).map(&:to_sym)
+            if @only
+              Array(@only).map(&:to_sym)
+            elsif @except
+              default_actions - Array(@except).map(&:to_sym)
             else
               default_actions
             end
@@ -1087,7 +1169,7 @@ module ActionDispatch
           end
 
           def resource_scope
-            { :controller => controller }
+            controller
           end
 
           alias :collection_scope :path
@@ -1110,17 +1192,15 @@ module ActionDispatch
             "#{path}/:#{nested_param}"
           end
 
-          def shallow=(value)
-            @shallow = value
-          end
-
           def shallow?
             @shallow
           end
+
+          def singleton?; false; end
         end
 
         class SingletonResource < Resource #:nodoc:
-          def initialize(entities, options)
+          def initialize(entities, api_only, shallow, options)
             super
             @as         = nil
             @controller = (options[:controller] || plural).to_s
@@ -1128,7 +1208,11 @@ module ActionDispatch
           end
 
           def default_actions
-            [:show, :create, :update, :destroy, :new, :edit]
+            if @api_only
+              [:show, :create, :update, :destroy]
+            else
+              [:show, :create, :update, :destroy, :new, :edit]
+            end
           end
 
           def plural
@@ -1144,6 +1228,8 @@ module ActionDispatch
 
           alias :member_scope :path
           alias :nested_scope :path
+
+          def singleton?; true; end
         end
 
         def resources_path_names(options)
@@ -1178,20 +1264,23 @@ module ActionDispatch
             return self
           end
 
-          resource_scope(:resource, SingletonResource.new(resources.pop, options)) do
-            yield if block_given?
+          with_scope_level(:resource) do
+            options = apply_action_options options
+            resource_scope(SingletonResource.new(resources.pop, api_only?, @scope[:shallow], options)) do
+              yield if block_given?
 
-            concerns(options[:concerns]) if options[:concerns]
+              concerns(options[:concerns]) if options[:concerns]
 
-            collection do
-              post :create
-            end if parent_resource.actions.include?(:create)
+              collection do
+                post :create
+              end if parent_resource.actions.include?(:create)
 
-            new do
-              get :new
-            end if parent_resource.actions.include?(:new)
+              new do
+                get :new
+              end if parent_resource.actions.include?(:new)
 
-            set_member_mappings_for_resource
+              set_member_mappings_for_resource
+            end
           end
 
           self
@@ -1336,21 +1425,24 @@ module ActionDispatch
             return self
           end
 
-          resource_scope(:resources, Resource.new(resources.pop, options)) do
-            yield if block_given?
+          with_scope_level(:resources) do
+            options = apply_action_options options
+            resource_scope(Resource.new(resources.pop, api_only?, @scope[:shallow], options)) do
+              yield if block_given?
 
-            concerns(options[:concerns]) if options[:concerns]
+              concerns(options[:concerns]) if options[:concerns]
 
-            collection do
-              get  :index if parent_resource.actions.include?(:index)
-              post :create if parent_resource.actions.include?(:create)
-            end
+              collection do
+                get  :index if parent_resource.actions.include?(:index)
+                post :create if parent_resource.actions.include?(:create)
+              end
 
-            new do
-              get :new
-            end if parent_resource.actions.include?(:new)
+              new do
+                get :new
+              end if parent_resource.actions.include?(:new)
 
-            set_member_mappings_for_resource
+              set_member_mappings_for_resource
+            end
           end
 
           self
@@ -1374,7 +1466,7 @@ module ActionDispatch
           end
 
           with_scope_level(:collection) do
-            scope(parent_resource.collection_scope) do
+            path_scope(parent_resource.collection_scope) do
               yield
             end
           end
@@ -1398,9 +1490,11 @@ module ActionDispatch
 
           with_scope_level(:member) do
             if shallow?
-              shallow_scope(parent_resource.member_scope) { yield }
+              shallow_scope {
+                path_scope(parent_resource.member_scope) { yield }
+              }
             else
-              scope(parent_resource.member_scope) { yield }
+              path_scope(parent_resource.member_scope) { yield }
             end
           end
         end
@@ -1411,7 +1505,7 @@ module ActionDispatch
           end
 
           with_scope_level(:new) do
-            scope(parent_resource.new_scope(action_path(:new))) do
+            path_scope(parent_resource.new_scope(action_path(:new))) do
               yield
             end
           end
@@ -1424,9 +1518,15 @@ module ActionDispatch
 
           with_scope_level(:nested) do
             if shallow? && shallow_nesting_depth >= 1
-              shallow_scope(parent_resource.nested_scope, nested_options) { yield }
+              shallow_scope do
+                path_scope(parent_resource.nested_scope) do
+                  scope(nested_options) { yield }
+                end
+              end
             else
-              scope(parent_resource.nested_scope, nested_options) { yield }
+              path_scope(parent_resource.nested_scope) do
+                scope(nested_options) { yield }
+              end
             end
           end
         end
@@ -1441,18 +1541,22 @@ module ActionDispatch
         end
 
         def shallow
-          scope(:shallow => true) do
-            yield
-          end
+          @scope = @scope.new(shallow: true)
+          yield
+        ensure
+          @scope = @scope.parent
         end
 
         def shallow?
-          parent_resource.instance_of?(Resource) && @scope[:shallow]
+          !parent_resource.singleton? && @scope[:shallow]
         end
 
-        # match 'path' => 'controller#action'
-        # match 'path', to: 'controller#action'
-        # match 'path', 'otherpath', on: :member, via: :get
+        # Matches a url pattern to one or more routes.
+        # For more information, see match[rdoc-ref:Base#match].
+        #
+        #   match 'path' => 'controller#action', via: patch
+        #   match 'path', to: 'controller#action', via: :post
+        #   match 'path', 'otherpath', on: :member, via: :get
         def match(path, *rest)
           if rest.empty? && Hash === path
             options  = path
@@ -1478,8 +1582,6 @@ module ActionDispatch
             paths = [path] + rest
           end
 
-          options[:anchor] = true unless options.key?(:anchor)
-
           if options[:on] && !VALID_ON_OPTIONS.include?(options[:on])
             raise ArgumentError, "Unknown scope #{on.inspect} given to :on"
           end
@@ -1488,48 +1590,85 @@ module ActionDispatch
             options[:to] ||= "#{@scope[:controller]}##{@scope[:action]}"
           end
 
-          paths.each do |_path|
+          controller = options.delete(:controller) || @scope[:controller]
+          option_path = options.delete :path
+          to = options.delete :to
+          via = Mapping.check_via Array(options.delete(:via) {
+            @scope[:via]
+          })
+          formatted = options.delete(:format) { @scope[:format] }
+          anchor = options.delete(:anchor) { true }
+          options_constraints = options.delete(:constraints) || {}
+
+          path_types = paths.group_by(&:class)
+          path_types.fetch(String, []).each do |_path|
             route_options = options.dup
-            route_options[:path] ||= _path if _path.is_a?(String)
+            if _path && option_path
+              ActiveSupport::Deprecation.warn <<-eowarn
+Specifying strings for both :path and the route path is deprecated.  Change things like this:
+
+  match #{_path.inspect}, :path => #{option_path.inspect}
 
-            path_without_format = _path.to_s.sub(/\(\.:format\)$/, '')
-            if using_match_shorthand?(path_without_format, route_options)
-              route_options[:to] ||= path_without_format.gsub(%r{^/}, "").sub(%r{/([^/]*)$}, '#\1')
-              route_options[:to].tr!("-", "_")
+to this:
+
+  match #{option_path.inspect}, :as => #{_path.inspect}, :action => #{path.inspect}
+              eowarn
+              route_options[:action] = _path
+              route_options[:as] = _path
+              _path = option_path
             end
+            to = get_to_from_path(_path, to, route_options[:action])
+            decomposed_match(_path, controller, route_options, _path, to, via, formatted, anchor, options_constraints)
+          end
 
-            decomposed_match(_path, route_options)
+          path_types.fetch(Symbol, []).each do |action|
+            route_options = options.dup
+            decomposed_match(action, controller, route_options, option_path, to, via, formatted, anchor, options_constraints)
           end
+
           self
         end
 
-        def using_match_shorthand?(path, options)
-          path && (options[:to] || options[:action]).nil? && path =~ %r{/[\w/]+$}
+        def get_to_from_path(path, to, action)
+          return to if to || action
+
+          path_without_format = path.sub(/\(\.:format\)$/, '')
+          if using_match_shorthand?(path_without_format)
+            path_without_format.gsub(%r{^/}, "").sub(%r{/([^/]*)$}, '#\1').tr("-", "_")
+          else
+            nil
+          end
+        end
+
+        def using_match_shorthand?(path)
+          path =~ %r{^/?[-\w]+/[-\w/]+$}
         end
 
-        def decomposed_match(path, options) # :nodoc:
+        def decomposed_match(path, controller, options, _path, to, via, formatted, anchor, options_constraints) # :nodoc:
           if on = options.delete(:on)
-            send(on) { decomposed_match(path, options) }
+            send(on) { decomposed_match(path, controller, options, _path, to, via, formatted, anchor, options_constraints) }
           else
             case @scope.scope_level
             when :resources
-              nested { decomposed_match(path, options) }
+              nested { decomposed_match(path, controller, options, _path, to, via, formatted, anchor, options_constraints) }
             when :resource
-              member { decomposed_match(path, options) }
+              member { decomposed_match(path, controller, options, _path, to, via, formatted, anchor, options_constraints) }
             else
-              add_route(path, options)
+              add_route(path, controller, options, _path, to, via, formatted, anchor, options_constraints)
             end
           end
         end
 
-        def add_route(action, options) # :nodoc:
-          path = path_for_action(action, options.delete(:path))
+        def add_route(action, controller, options, _path, to, via, formatted, anchor, options_constraints) # :nodoc:
+          path = path_for_action(action, _path)
           raise ArgumentError, "path is required" if path.blank?
 
-          action = action.to_s.dup
+          action = action.to_s
+
+          default_action = options.delete(:action) || @scope[:action]
 
           if action =~ /^[\w\-\/]+$/
-            options[:action] ||= action.tr('-', '_') unless action.include?("/")
+            default_action ||= action.tr('-', '_') unless action.include?("/")
           else
             action = nil
           end
@@ -1540,9 +1679,11 @@ module ActionDispatch
                  name_for_action(options.delete(:as), action)
                end
 
-          mapping = Mapping.build(@scope, @set, URI.parser.escape(path), as, options)
-          app, conditions, requirements, defaults, as, anchor = mapping.to_route
-          @set.add_route(app, conditions, requirements, defaults, as, anchor)
+          path = Mapping.normalize_path URI.parser.escape(path), formatted
+          ast = Journey::Parser.parse path
+
+          mapping = Mapping.build(@scope, @set, ast, controller, default_action, to, via, formatted, options_constraints, anchor, options)
+          @set.add_route(mapping, ast, as, anchor)
         end
 
         def root(path, options={})
@@ -1556,7 +1697,7 @@ module ActionDispatch
 
           if @scope.resources?
             with_scope_level(:root) do
-              scope(parent_resource.path) do
+              path_scope(parent_resource.path) do
                 super(options)
               end
             end
@@ -1601,23 +1742,20 @@ module ActionDispatch
               return true
             end
 
-            unless action_options?(options)
-              options.merge!(scope_action_options) if scope_action_options?
-            end
-
             false
           end
 
-          def action_options?(options) #:nodoc:
-            options[:only] || options[:except]
+          def apply_action_options(options) # :nodoc:
+            return options if action_options? options
+            options.merge scope_action_options
           end
 
-          def scope_action_options? #:nodoc:
-            @scope[:options] && (@scope[:options][:only] || @scope[:options][:except])
+          def action_options?(options) #:nodoc:
+            options[:only] || options[:except]
           end
 
           def scope_action_options #:nodoc:
-            @scope[:options].slice(:only, :except)
+            @scope[:action_options] || {}
           end
 
           def resource_scope? #:nodoc:
@@ -1632,18 +1770,6 @@ module ActionDispatch
             @scope.nested?
           end
 
-          def with_exclusive_scope
-            begin
-              @scope = @scope.new(:as => nil, :path => nil)
-
-              with_scope_level(:exclusive) do
-                yield
-              end
-            ensure
-              @scope = @scope.parent
-            end
-          end
-
           def with_scope_level(kind)
             @scope = @scope.new_level(kind)
             yield
@@ -1651,16 +1777,11 @@ module ActionDispatch
             @scope = @scope.parent
           end
 
-          def resource_scope(kind, resource) #:nodoc:
-            resource.shallow = @scope[:shallow]
+          def resource_scope(resource) #:nodoc:
             @scope = @scope.new(:scope_level_resource => resource)
-            @nesting.push(resource)
 
-            with_scope_level(kind) do
-              scope(parent_resource.resource_scope) { yield }
-            end
+            controller(resource.resource_scope) { yield }
           ensure
-            @nesting.pop
             @scope = @scope.parent
           end
 
@@ -1673,12 +1794,10 @@ module ActionDispatch
             options
           end
 
-          def nesting_depth #:nodoc:
-            @nesting.size
-          end
-
           def shallow_nesting_depth #:nodoc:
-            @nesting.select(&:shallow?).size
+            @scope.find_all { |node|
+              node.frame[:scope_level_resource]
+            }.count { |node| node.frame[:scope_level_resource].shallow? }
           end
 
           def param_constraint? #:nodoc:
@@ -1693,27 +1812,28 @@ module ActionDispatch
             resource_method_scope? && CANONICAL_ACTIONS.include?(action.to_s)
           end
 
-          def shallow_scope(path, options = {}) #:nodoc:
+          def shallow_scope #:nodoc:
             scope = { :as   => @scope[:shallow_prefix],
                       :path => @scope[:shallow_path] }
             @scope = @scope.new scope
 
-            scope(path, options) { yield }
+            yield
           ensure
             @scope = @scope.parent
           end
 
           def path_for_action(action, path) #:nodoc:
-            if path.blank? && canonical_action?(action)
+            return "#{@scope[:path]}/#{path}" if path
+
+            if canonical_action?(action)
               @scope[:path].to_s
             else
-              "#{@scope[:path]}/#{action_path(action, path)}"
+              "#{@scope[:path]}/#{action_path(action)}"
             end
           end
 
-          def action_path(name, path = nil) #:nodoc:
-            name = name.to_sym if name.is_a?(String)
-            path || @scope[:path_names][name] || name.to_s
+          def action_path(name) #:nodoc:
+            @scope[:path_names][name.to_sym] || name
           end
 
           def prefix_name_for_action(as, action) #:nodoc:
@@ -1739,14 +1859,15 @@ module ActionDispatch
               member_name = parent_resource.member_name
             end
 
-            name = @scope.action_name(name_prefix, prefix, collection_name, member_name)
+            action_name = @scope.action_name(name_prefix, prefix, collection_name, member_name)
+            candidate = action_name.select(&:present?).join('_')
 
-            if candidate = name.compact.join("_").presence
+            unless candidate.empty?
               # If a name was not explicitly given, we check if it is valid
               # and return nil in case it isn't. Otherwise, we pass the invalid name
               # forward so the underlying router engine treats it and raises an exception.
               if as.nil?
-                candidate unless candidate !~ /\A[_a-z]/i || @set.named_routes.key?(candidate)
+                candidate unless candidate !~ /\A[_a-z]/i || has_named_route?(candidate)
               else
                 candidate
               end
@@ -1764,6 +1885,18 @@ module ActionDispatch
               delete :destroy if parent_resource.actions.include?(:destroy)
             end
           end
+
+          def api_only?
+            @set.api_only?
+          end
+        private
+
+        def path_scope(path)
+          @scope = @scope.new(path: merge_path_scope(@scope[:path], path))
+          yield
+        ensure
+          @scope = @scope.parent
+        end
       end
 
       # Routing Concerns allow you to declare common routes that can be reused
@@ -1874,14 +2007,14 @@ module ActionDispatch
       class Scope # :nodoc:
         OPTIONS = [:path, :shallow_path, :as, :shallow_prefix, :module,
                    :controller, :action, :path_names, :constraints,
-                   :shallow, :blocks, :defaults, :options]
+                   :shallow, :blocks, :defaults, :via, :format, :options]
 
         RESOURCE_SCOPES = [:resource, :resources]
         RESOURCE_METHOD_SCOPES = [:collection, :member, :new]
 
         attr_reader :parent, :scope_level
 
-        def initialize(hash, parent = {}, scope_level = nil)
+        def initialize(hash, parent = NULL, scope_level = nil)
           @hash = hash
           @parent = parent
           @scope_level = scope_level
@@ -1929,27 +2062,34 @@ module ActionDispatch
         end
 
         def new_level(level)
-          self.class.new(self, self, level)
-        end
-
-        def fetch(key, &block)
-          @hash.fetch(key, &block)
+          self.class.new(frame, self, level)
         end
 
         def [](key)
-          @hash.fetch(key) { @parent[key] }
+          scope = find { |node| node.frame.key? key }
+          scope && scope.frame[key]
         end
 
-        def []=(k,v)
-          @hash[k] = v
+        include Enumerable
+
+        def each
+          node = self
+          loop do
+            break if node.equal? NULL
+            yield node
+            node = node.parent
+          end
         end
+
+        def frame; @hash; end
+
+        NULL = Scope.new(nil, nil)
       end
 
       def initialize(set) #:nodoc:
         @set = set
         @scope = Scope.new({ :path_names => @set.resources_path_names })
         @concerns = {}
-        @nesting = []
       end
 
       include Base
diff --git a/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb b/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb
index 2e116ea9cd..9934f5547a 100644
--- a/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb
+++ b/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb
@@ -247,14 +247,12 @@ module ActionDispatch
           args  = []
 
           model = record.to_model
-          name = if model.persisted?
-                   args << model
-                   model.model_name.singular_route_key
-                 else
-                   @key_strategy.call model.model_name
-                 end
-
-          named_route = prefix + "#{name}_#{suffix}"
+          named_route = if model.persisted?
+                          args << model
+                          get_method_for_string model.model_name.singular_route_key
+                        else
+                          get_method_for_class model
+                        end
 
           [named_route, args]
         end
@@ -309,11 +307,11 @@ module ActionDispatch
 
         def get_method_for_class(klass)
           name   = @key_strategy.call klass.model_name
-          prefix + "#{name}_#{suffix}"
+          get_method_for_string name
         end
 
         def get_method_for_string(str)
-          prefix + "#{str}_#{suffix}"
+          "#{prefix}#{str}_#{suffix}"
         end
 
         [nil, 'new', 'edit'].each do |action|
diff --git a/actionpack/lib/action_dispatch/routing/redirection.rb b/actionpack/lib/action_dispatch/routing/redirection.rb
index 3c1c4fadf6..d6987f4d09 100644
--- a/actionpack/lib/action_dispatch/routing/redirection.rb
+++ b/actionpack/lib/action_dispatch/routing/redirection.rb
@@ -24,7 +24,7 @@ module ActionDispatch
       def serve(req)
         req.check_path_parameters!
         uri = URI.parse(path(req.path_parameters, req))
-        
+
         unless uri.host
           if relative_path?(uri.path)
             uri.path = "#{req.script_name}/#{uri.path}"
@@ -32,7 +32,7 @@ module ActionDispatch
             uri.path = req.script_name.empty? ? "/" : req.script_name
           end
         end
-          
+
         uri.scheme ||= req.scheme
         uri.host   ||= req.host
         uri.port   ||= req.port unless req.standard_port?
@@ -124,7 +124,7 @@ module ActionDispatch
             url_options[:script_name] = request.script_name
           end
         end
-        
+
         ActionDispatch::Http::URL.url_for url_options
       end
 
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index b4c861d306..5f54ea130b 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -1,6 +1,4 @@
 require 'action_dispatch/journey'
-require 'forwardable'
-require 'thread_safe'
 require 'active_support/concern'
 require 'active_support/core_ext/object/to_query'
 require 'active_support/core_ext/hash/slice'
@@ -12,81 +10,63 @@ require 'action_dispatch/routing/endpoint'
 
 module ActionDispatch
   module Routing
-    class RouteSet #:nodoc:
+    # :stopdoc:
+    class RouteSet
       # Since the router holds references to many parts of the system
       # like engines, controllers and the application itself, inspecting
       # the route set can actually be really slow, therefore we default
       # alias inspect to to_s.
       alias inspect to_s
 
-      class Dispatcher < Routing::Endpoint #:nodoc:
-        def initialize(defaults)
-          @defaults = defaults
-          @controller_class_names = ThreadSafe::Cache.new
+      class Dispatcher < Routing::Endpoint
+        def initialize(raise_on_name_error)
+          @raise_on_name_error = raise_on_name_error
         end
 
         def dispatcher?; true; end
 
         def serve(req)
-          req.check_path_parameters!
-          params = req.path_parameters
-
-          prepare_params!(params)
-
-          # Just raise undefined constant errors if a controller was specified as default.
-          unless controller = controller(params, @defaults.key?(:controller))
+          params     = req.path_parameters
+          controller = controller req
+          res        = controller.make_response! req
+          dispatch(controller, params[:action], req, res)
+        rescue NameError => e
+          if @raise_on_name_error
+            raise ActionController::RoutingError, e.message, e.backtrace
+          else
             return [404, {'X-Cascade' => 'pass'}, []]
           end
-
-          dispatch(controller, params[:action], req.env)
-        end
-
-        def prepare_params!(params)
-          normalize_controller!(params)
-          merge_default_action!(params)
-        end
-
-        # If this is a default_controller (i.e. a controller specified by the user)
-        # we should raise an error in case it's not found, because it usually means
-        # a user error. However, if the controller was retrieved through a dynamic
-        # segment, as in :controller(/:action), we should simply return nil and
-        # delegate the control back to Rack cascade. Besides, if this is not a default
-        # controller, it means we should respect the @scope[:module] parameter.
-        def controller(params, default_controller=true)
-          if params && params.key?(:controller)
-            controller_param = params[:controller]
-            controller_reference(controller_param)
-          end
-        rescue NameError => e
-          raise ActionController::RoutingError, e.message, e.backtrace if default_controller
         end
 
       private
 
-        def controller_reference(controller_param)
-          const_name = @controller_class_names[controller_param] ||= "#{controller_param.camelize}Controller"
-          ActiveSupport::Dependencies.constantize(const_name)
+        def controller(req)
+          req.controller_class
         end
 
-        def dispatch(controller, action, env)
-          controller.action(action).call(env)
+        def dispatch(controller, action, req, res)
+          controller.dispatch(action, req, res)
         end
+      end
 
-        def normalize_controller!(params)
-          params[:controller] = params[:controller].underscore if params.key?(:controller)
+      class StaticDispatcher < Dispatcher
+        def initialize(controller_class)
+          super(false)
+          @controller_class = controller_class
         end
 
-        def merge_default_action!(params)
-          params[:action] ||= 'index'
-        end
+        private
+
+        def controller(_); @controller_class; end
       end
 
       # A NamedRouteCollection instance is a collection of named routes, and also
       # maintains an anonymous module that can be used to install helpers for the
       # named routes.
-      class NamedRouteCollection #:nodoc:
+      class NamedRouteCollection
         include Enumerable
         attr_reader :routes, :url_helpers_module, :path_helpers_module
+        private :routes
 
         def initialize
           @routes  = {}
@@ -141,6 +121,7 @@ module ActionDispatch
         end
 
         def key?(name)
+          return unless name
           routes.key? name.to_sym
         end
 
@@ -161,7 +142,7 @@ module ActionDispatch
           routes.length
         end
 
-        class UrlHelper # :nodoc:
+        class UrlHelper
           def self.create(route, options, route_name, url_strategy)
             if optimize_helper?(route)
               OptimizedUrlHelper.new(route, options, route_name, url_strategy)
@@ -176,7 +157,7 @@ module ActionDispatch
 
           attr_reader :url_strategy, :route_name
 
-          class OptimizedUrlHelper < UrlHelper # :nodoc:
+          class OptimizedUrlHelper < UrlHelper
             attr_reader :arg_size
 
             def initialize(route, options, route_name, url_strategy)
@@ -198,11 +179,8 @@ module ActionDispatch
             private
 
             def optimized_helper(args)
-              params = parameterize_args(args)
-              missing_keys = missing_keys(params)
-
-              unless missing_keys.empty?
-                raise_generation_error(params, missing_keys)
+              params = parameterize_args(args) do
+                raise_generation_error(args)
               end
 
               @route.format params
@@ -214,16 +192,21 @@ module ActionDispatch
 
             def parameterize_args(args)
               params = {}
-              @required_parts.zip(args.map(&:to_param)) { |k,v| params[k] = v }
+              @arg_size.times { |i|
+                key = @required_parts[i]
+                value = args[i].to_param
+                yield key if value.nil? || value.empty?
+                params[key] = value
+              }
               params
             end
 
-            def missing_keys(args)
-              args.select{ |part, arg| arg.nil? || arg.empty? }.keys
-            end
-
-            def raise_generation_error(args, missing_keys)
-              constraints = Hash[@route.requirements.merge(args).sort]
+            def raise_generation_error(args)
+              missing_keys = []
+              params = parameterize_args(args) { |missing_key|
+                missing_keys << missing_key
+              }
+              constraints = Hash[@route.requirements.merge(params).sort_by{|k,v| k.to_s}]
               message = "No route matches #{constraints.inspect}"
               message << " missing required keys: #{missing_keys.sort.inspect}"
 
@@ -264,9 +247,14 @@ module ActionDispatch
                 path_params -= controller_options.keys
                 path_params -= result.keys
               end
-              path_params.each { |param|
-                result[param] = inner_options.fetch(param) { args.shift }
-              }
+              inner_options.each_key do |key|
+                path_params.delete(key)
+              end
+
+              args.each_with_index do |arg, index|
+                param = path_params[index]
+                result[param] = arg if param
+              end
             end
 
             result.merge!(inner_options)
@@ -299,15 +287,14 @@ module ActionDispatch
         end
       end
 
-      # :stopdoc:
       # strategy for building urls to send to the client
       PATH    = ->(options) { ActionDispatch::Http::URL.path_for(options) }
       UNKNOWN = ->(options) { ActionDispatch::Http::URL.url_for(options) }
-      # :startdoc:
 
       attr_accessor :formatter, :set, :named_routes, :default_scope, :router
       attr_accessor :disable_clear_and_finalize, :resources_path_names
-      attr_accessor :default_url_options, :request_class
+      attr_accessor :default_url_options
+      attr_reader :env_key
 
       alias :routes :set
 
@@ -315,22 +302,59 @@ module ActionDispatch
         { :new => 'new', :edit => 'edit' }
       end
 
-      def initialize(request_class = ActionDispatch::Request)
+      def self.new_with_config(config)
+        route_set_config = DEFAULT_CONFIG
+
+        # engines apparently don't have this set
+        if config.respond_to? :relative_url_root
+          route_set_config.relative_url_root = config.relative_url_root
+        end
+
+        if config.respond_to? :api_only
+          route_set_config.api_only = config.api_only
+        end
+
+        new route_set_config
+      end
+
+      Config = Struct.new :relative_url_root, :api_only
+
+      DEFAULT_CONFIG = Config.new(nil, false)
+
+      def initialize(config = DEFAULT_CONFIG)
         self.named_routes = NamedRouteCollection.new
         self.resources_path_names = self.class.default_resources_path_names
         self.default_url_options = {}
-        self.request_class = request_class
 
+        @config                     = config
         @append                     = []
         @prepend                    = []
         @disable_clear_and_finalize = false
         @finalized                  = false
+        @env_key                    = "ROUTES_#{object_id}_SCRIPT_NAME".freeze
 
         @set    = Journey::Routes.new
         @router = Journey::Router.new @set
-        @formatter = Journey::Formatter.new @set
+        @formatter = Journey::Formatter.new self
+      end
+
+      def relative_url_root
+        @config.relative_url_root
+      end
+
+      def api_only?
+        @config.api_only
       end
 
+      def request_class
+        ActionDispatch::Request
+      end
+
+      def make_request(env)
+        request_class.new env
+      end
+      private :make_request
+
       def draw(&block)
         clear! unless @disable_clear_and_finalize
         eval_block(block)
@@ -374,11 +398,7 @@ module ActionDispatch
         @prepend.each { |blk| eval_block(blk) }
       end
 
-      def dispatcher(defaults)
-        Routing::RouteSet::Dispatcher.new(defaults)
-      end
-
-      module MountedHelpers #:nodoc:
+      module MountedHelpers
         extend ActiveSupport::Concern
         include UrlFor
       end
@@ -395,9 +415,11 @@ module ActionDispatch
         return if MountedHelpers.method_defined?(name)
 
         routes = self
+        helpers = routes.url_helpers
+
         MountedHelpers.class_eval do
           define_method "_#{name}" do
-            RoutesProxy.new(routes, _routes_context)
+            RoutesProxy.new(routes, _routes_context, helpers)
           end
         end
 
@@ -419,7 +441,14 @@ module ActionDispatch
           # Rails.application.routes.url_helpers.url_for(args)
           @_routes = routes
           class << self
-            delegate :url_for, :optimize_routes_generation?, to: '@_routes'
+            def url_for(options)
+              @_routes.url_for(options)
+            end
+
+            def optimize_routes_generation?
+              @_routes.optimize_routes_generation?
+            end
+
             attr_reader :_routes
             def url_options; {}; end
           end
@@ -464,7 +493,7 @@ module ActionDispatch
         routes.empty?
       end
 
-      def add_route(app, conditions = {}, requirements = {}, defaults = {}, name = nil, anchor = true)
+      def add_route(mapping, path_ast, name, anchor)
         raise ArgumentError, "Invalid route name: '#{name}'" unless name.blank? || name.to_s.match(/^[_a-z]\w*$/i)
 
         if name && named_routes[name]
@@ -475,74 +504,17 @@ module ActionDispatch
             "http://guides.rubyonrails.org/routing.html#restricting-the-routes-created"
         end
 
-        path = conditions.delete :path_info
-        ast  = conditions.delete :parsed_path_info
-        path = build_path(path, ast, requirements, anchor)
-        conditions = build_conditions(conditions, path.names.map(&:to_sym))
-
-        route = @set.add_route(app, path, conditions, defaults, name)
+        route = @set.add_route(name, mapping)
         named_routes[name] = route if name
         route
       end
 
-      def build_path(path, ast, requirements, anchor)
-        strexp = Journey::Router::Strexp.new(
-            ast,
-            path,
-            requirements,
-            SEPARATORS,
-            anchor)
-
-        pattern = Journey::Path::Pattern.new(strexp)
-
-        builder = Journey::GTG::Builder.new pattern.spec
-
-        # Get all the symbol nodes followed by literals that are not the
-        # dummy node.
-        symbols = pattern.spec.grep(Journey::Nodes::Symbol).find_all { |n|
-          builder.followpos(n).first.literal?
-        }
-
-        # Get all the symbol nodes preceded by literals.
-        symbols.concat pattern.spec.find_all(&:literal?).map { |n|
-          builder.followpos(n).first
-        }.find_all(&:symbol?)
-
-        symbols.each { |x|
-          x.regexp = /(?:#{Regexp.union(x.regexp, '-')})+/
-        }
-
-        pattern
-      end
-      private :build_path
-
-      def build_conditions(current_conditions, path_values)
-        conditions = current_conditions.dup
-
-        # Rack-Mount requires that :request_method be a regular expression.
-        # :request_method represents the HTTP verb that matches this route.
-        #
-        # Here we munge values before they get sent on to rack-mount.
-        verbs = conditions[:request_method] || []
-        unless verbs.empty?
-          conditions[:request_method] = %r[^#{verbs.join('|')}$]
-        end
-
-        conditions.keep_if do |k, _|
-          k == :action || k == :controller || k == :required_defaults ||
-            @request_class.public_method_defined?(k) || path_values.include?(k)
-        end
-      end
-      private :build_conditions
-
-      class Generator #:nodoc:
+      class Generator
         PARAMETERIZE = lambda do |name, value|
           if name == :controller
             value
-          elsif value.is_a?(Array)
-            value.map(&:to_param).join('/')
-          elsif param = value.to_param
-            param
+          else
+            value.to_param
           end
         end
 
@@ -550,8 +522,8 @@ module ActionDispatch
 
         def initialize(named_route, options, recall, set)
           @named_route = named_route
-          @options     = options.dup
-          @recall      = recall.dup
+          @options     = options
+          @recall      = recall
           @set         = set
 
           normalize_recall!
@@ -573,7 +545,7 @@ module ActionDispatch
         def use_recall_for(key)
           if @recall[key] && (!@options.key?(key) || @options[key] == @recall[key])
             if !named_route_exists? || segment_keys.include?(key)
-              @options[key] = @recall.delete(key)
+              @options[key] = @recall[key]
             end
           end
         end
@@ -627,12 +599,18 @@ module ActionDispatch
 
         # Remove leading slashes from controllers
         def normalize_controller!
-          @options[:controller] = controller.sub(%r{^/}, '') if controller
+          if controller
+            if controller.start_with?("/".freeze)
+              @options[:controller] = controller[1..-1]
+            else
+              @options[:controller] = controller
+            end
+          end
         end
 
         # Move 'index' action from options to recall
         def normalize_action!
-          if @options[:action] == 'index'
+          if @options[:action] == 'index'.freeze
             @recall[:action] = @options.delete(:action)
           end
         end
@@ -677,17 +655,21 @@ module ActionDispatch
 
       RESERVED_OPTIONS = [:host, :protocol, :port, :subdomain, :domain, :tld_length,
                           :trailing_slash, :anchor, :params, :only_path, :script_name,
-                          :original_script_name]
+                          :original_script_name, :relative_url_root]
 
       def optimize_routes_generation?
         default_url_options.empty?
       end
 
       def find_script_name(options)
-        options.delete(:script_name) || ''
+        options.delete(:script_name) || find_relative_url_root(options) || ''
+      end
+
+      def find_relative_url_root(options)
+        options.delete(:relative_url_root) || relative_url_root
       end
 
-      def path_for(options, route_name = nil) # :nodoc:
+      def path_for(options, route_name = nil)
         url_for(options, route_name, PATH)
       end
 
@@ -730,7 +712,7 @@ module ActionDispatch
       end
 
       def call(env)
-        req = request_class.new(env)
+        req = make_request(env)
         req.path_info = Journey::Router::Utils.normalize_path(req.path_info)
         @router.serve(req)
       end
@@ -746,7 +728,7 @@ module ActionDispatch
           raise ActionController::RoutingError, e.message
         end
 
-        req = request_class.new(env)
+        req = make_request(env)
         @router.recognize(req) do |route, params|
           params.merge!(extras)
           params.each do |key, value|
@@ -759,19 +741,19 @@ module ActionDispatch
           req.path_parameters = old_params.merge params
           app = route.app
           if app.matches?(req) && app.dispatcher?
-            dispatcher = app.app
-
-            if dispatcher.controller(params, false)
-              dispatcher.prepare_params!(params)
-              return params
-            else
+            begin
+              req.controller_class
+            rescue NameError
               raise ActionController::RoutingError, "A route matches #{path.inspect}, but references missing controller: #{params[:controller].camelize}Controller"
             end
+
+            return req.path_parameters
           end
         end
 
         raise ActionController::RoutingError, "No route matches #{path.inspect}"
       end
     end
+    # :startdoc:
   end
 end
diff --git a/actionpack/lib/action_dispatch/routing/routes_proxy.rb b/actionpack/lib/action_dispatch/routing/routes_proxy.rb
index e2393d3799..040ea04046 100644
--- a/actionpack/lib/action_dispatch/routing/routes_proxy.rb
+++ b/actionpack/lib/action_dispatch/routing/routes_proxy.rb
@@ -8,8 +8,9 @@ module ActionDispatch
       attr_accessor :scope, :routes
       alias :_routes :routes
 
-      def initialize(routes, scope)
+      def initialize(routes, scope, helpers)
         @routes, @scope = routes, scope
+        @helpers = helpers
       end
 
       def url_options
@@ -19,16 +20,16 @@ module ActionDispatch
       end
 
       def respond_to?(method, include_private = false)
-        super || routes.url_helpers.respond_to?(method)
+        super || @helpers.respond_to?(method)
       end
 
       def method_missing(method, *args)
-        if routes.url_helpers.respond_to?(method)
+        if @helpers.respond_to?(method)
           self.class.class_eval <<-RUBY, __FILE__, __LINE__ + 1
             def #{method}(*args)
               options = args.extract_options!
               args << url_options.merge((options || {}).symbolize_keys)
-              routes.url_helpers.#{method}(*args)
+              @helpers.#{method}(*args)
             end
           RUBY
           send(method, *args)
diff --git a/actionpack/lib/action_dispatch/routing/url_for.rb b/actionpack/lib/action_dispatch/routing/url_for.rb
index dca86858cc..b6c031dcf4 100644
--- a/actionpack/lib/action_dispatch/routing/url_for.rb
+++ b/actionpack/lib/action_dispatch/routing/url_for.rb
@@ -1,7 +1,7 @@
 module ActionDispatch
   module Routing
     # In <tt>config/routes.rb</tt> you define URL-to-controller mappings, but the reverse
-    # is also possible: an URL can be generated from one of your routing definitions.
+    # is also possible: a URL can be generated from one of your routing definitions.
     # URL generation functionality is centralized in this module.
     #
     # See ActionDispatch::Routing for general information about routing and routes.rb.
@@ -52,9 +52,11 @@ module ActionDispatch
     # argument.
     #
     # For convenience reasons, mailers provide a shortcut for ActionController::UrlFor#url_for.
-    # So within mailers, you only have to type 'url_for' instead of 'ActionController::UrlFor#url_for'
-    # in full. However, mailers don't have hostname information, and that's why you'll still
-    # have to specify the <tt>:host</tt> argument when generating URLs in mailers.
+    # So within mailers, you only have to type +url_for+ instead of 'ActionController::UrlFor#url_for'
+    # in full. However, mailers don't have hostname information, and you still have to provide
+    # the +:host+ argument or set the default host that will be used in all mailers using the
+    # configuration option +config.action_mailer.default_url_options+. For more information on
+    # url_for in mailers read the ActionMailer#Base documentation.
     #
     #
     # == URL generation for named routes
@@ -147,6 +149,20 @@ module ActionDispatch
       #    # => 'http://somehost.org/myapp/tasks/testing'
       #    url_for controller: 'tasks', action: 'testing', host: 'somehost.org', script_name: "/myapp", only_path: true
       #    # => '/myapp/tasks/testing'
+      #
+      # Missing routes keys may be filled in from the current request's parameters
+      # (e.g. +:controller+, +:action+, +:id+ and any other parameters that are
+      # placed in the path). Given that the current action has been reached
+      # through `GET /users/1`:
+      #
+      #   url_for(only_path: true)                        # => '/users/1'
+      #   url_for(only_path: true, action: 'edit')        # => '/users/1/edit'
+      #   url_for(only_path: true, action: 'edit', id: 2) # => '/users/2/edit'
+      #
+      # Notice that no +:id+ parameter was provided to the first +url_for+ call
+      # and the helper used the one from the route's path. Any path parameter
+      # implicitly used by +url_for+ can always be overwritten like shown on the
+      # last +url_for+ calls.
       def url_for(options = nil)
         case options
         when nil
@@ -155,12 +171,17 @@ module ActionDispatch
           route_name = options.delete :use_route
           _routes.url_for(options.symbolize_keys.reverse_merge!(url_options),
                          route_name)
+        when ActionController::Parameters
+          route_name = options.delete :use_route
+          _routes.url_for(options.to_unsafe_h.symbolize_keys.
+                          reverse_merge!(url_options), route_name)
         when String
           options
         when Symbol
           HelperMethodBuilder.url.handle_string_call self, options
         when Array
-          polymorphic_url(options, options.extract_options!)
+          components = options.dup
+          polymorphic_url(components, components.extract_options!)
         when Class
           HelperMethodBuilder.url.handle_class_call self, options
         else
@@ -184,12 +205,6 @@ module ActionDispatch
       def _routes_context
         self
       end
-
-      private
-
-        def _generate_paths_by_default
-          true
-        end
     end
   end
 end
diff --git a/actionpack/lib/action_dispatch/testing/assertions.rb b/actionpack/lib/action_dispatch/testing/assertions.rb
index f325c35b57..fae266273e 100644
--- a/actionpack/lib/action_dispatch/testing/assertions.rb
+++ b/actionpack/lib/action_dispatch/testing/assertions.rb
@@ -12,7 +12,7 @@ module ActionDispatch
     include Rails::Dom::Testing::Assertions
 
     def html_document
-      @html_document ||= if @response.content_type =~ /xml$/
+      @html_document ||= if @response.content_type.to_s =~ /xml\z/
         Nokogiri::XML::Document.parse(@response.body)
       else
         Nokogiri::HTML::Document.parse(@response.body)
diff --git a/actionpack/lib/action_dispatch/testing/assertions/response.rb b/actionpack/lib/action_dispatch/testing/assertions/response.rb
index 13a72220b3..b6e21b0d28 100644
--- a/actionpack/lib/action_dispatch/testing/assertions/response.rb
+++ b/actionpack/lib/action_dispatch/testing/assertions/response.rb
@@ -3,6 +3,13 @@ module ActionDispatch
   module Assertions
     # A small suite of assertions that test responses from \Rails applications.
     module ResponseAssertions
+      RESPONSE_PREDICATES = { # :nodoc:
+        success:  :successful?,
+        missing:  :not_found?,
+        redirect: :redirection?,
+        error:    :server_error?,
+      }
+
       # Asserts that the response is one of the following types:
       #
       # * <tt>:success</tt>   - Status code was in the 200-299 range
@@ -20,11 +27,9 @@ module ActionDispatch
       #   # assert that the response code was status code 401 (unauthorized)
       #   assert_response 401
       def assert_response(type, message = nil)
-        message ||= "Expected response to be a <#{type}>, but was <#{@response.response_code}>"
-
         if Symbol === type
           if [:success, :missing, :redirect, :error].include?(type)
-            assert @response.send("#{type}?"), message
+            assert_predicate @response, RESPONSE_PREDICATES[type], message
           else
             code = Rack::Utils::SYMBOL_TO_STATUS_CODE[type]
             if code.nil?
diff --git a/actionpack/lib/action_dispatch/testing/assertions/routing.rb b/actionpack/lib/action_dispatch/testing/assertions/routing.rb
index 28dc88d317..54e24ed6bf 100644
--- a/actionpack/lib/action_dispatch/testing/assertions/routing.rb
+++ b/actionpack/lib/action_dispatch/testing/assertions/routing.rb
@@ -38,18 +38,24 @@ module ActionDispatch
       #   # Test a custom route
       #   assert_recognizes({controller: 'items', action: 'show', id: '1'}, 'view/item1')
       def assert_recognizes(expected_options, path, extras={}, msg=nil)
-        request = recognized_request_for(path, extras, msg)
+        if path.is_a?(Hash) && path[:method].to_s == "all"
+          [:get, :post, :put, :delete].each do |method|
+            assert_recognizes(expected_options, path.merge(method: method), extras, msg)
+          end
+        else
+          request = recognized_request_for(path, extras, msg)
 
-        expected_options = expected_options.clone
+          expected_options = expected_options.clone
 
-        expected_options.stringify_keys!
+          expected_options.stringify_keys!
 
-        msg = message(msg, "") {
-          sprintf("The recognized options <%s> did not match <%s>, difference:",
-                  request.path_parameters, expected_options)
-        }
+          msg = message(msg, "") {
+            sprintf("The recognized options <%s> did not match <%s>, difference:",
+                    request.path_parameters, expected_options)
+          }
 
-        assert_equal(expected_options, request.path_parameters, msg)
+          assert_equal(expected_options, request.path_parameters, msg)
+        end
       end
 
       # Asserts that the provided options can be used to generate the provided path. This is the inverse of +assert_recognizes+.
@@ -80,8 +86,8 @@ module ActionDispatch
         end
         # Load routes.rb if it hasn't been loaded.
 
-        generated_path, extra_keys = @routes.generate_extras(options, defaults)
-        found_extras = options.reject { |k, _| ! extra_keys.include? k }
+        generated_path, query_string_keys = @routes.generate_extras(options, defaults)
+        found_extras = options.reject { |k, _| ! query_string_keys.include? k }
 
         msg = message || sprintf("found extras <%s>, not <%s>", found_extras, extras)
         assert_equal(extras, found_extras, msg)
@@ -144,7 +150,7 @@ module ActionDispatch
           old_controller, @controller = @controller, @controller.clone
           _routes = @routes
 
-          @controller.singleton_class.send(:include, _routes.url_helpers)
+          @controller.singleton_class.include(_routes.url_helpers)
           @controller.view_context_class = Class.new(@controller.view_context_class) do
             include _routes.url_helpers
           end
@@ -159,7 +165,7 @@ module ActionDispatch
 
       # ROUTES TODO: These assertions should really work in an integration context
       def method_missing(selector, *args, &block)
-        if defined?(@controller) && @controller && @routes && @routes.named_routes.route_defined?(selector)
+        if defined?(@controller) && @controller && defined?(@routes) && @routes && @routes.named_routes.route_defined?(selector)
           @controller.send(selector, *args, &block)
         else
           super
@@ -177,7 +183,7 @@ module ActionDispatch
           end
 
           # Assume given controller
-          request = ActionController::TestRequest.new
+          request = ActionController::TestRequest.create
 
           if path =~ %r{://}
             fail_on(URI::InvalidURIError, msg) do
diff --git a/actionpack/lib/action_dispatch/testing/integration.rb b/actionpack/lib/action_dispatch/testing/integration.rb
index f0e2c5becc..790f9ea5d2 100644
--- a/actionpack/lib/action_dispatch/testing/integration.rb
+++ b/actionpack/lib/action_dispatch/testing/integration.rb
@@ -2,6 +2,7 @@ require 'stringio'
 require 'uri'
 require 'active_support/core_ext/kernel/singleton_class'
 require 'active_support/core_ext/object/try'
+require 'active_support/core_ext/string/strip'
 require 'rack/test'
 require 'minitest'
 
@@ -12,12 +13,14 @@ module ActionDispatch
       #
       # - +path+: The URI (as a String) on which you want to perform a GET
       #   request.
-      # - +parameters+: The HTTP parameters that you want to pass. This may
+      # - +params+: The HTTP parameters that you want to pass. This may
       #   be +nil+,
       #   a Hash, or a String that is appropriately encoded
       #   (<tt>application/x-www-form-urlencoded</tt> or
       #   <tt>multipart/form-data</tt>).
-      # - +headers_or_env+: Additional headers to pass, as a Hash. The headers will be
+      # - +headers+: Additional headers to pass, as a Hash. The headers will be
+      #   merged into the Rack env hash.
+      # - +env+: Additional env to pass, as a Hash. The headers will be
       #   merged into the Rack env hash.
       #
       # This method returns a Response object, which one can use to
@@ -28,38 +31,43 @@ module ActionDispatch
       #
       # You can also perform POST, PATCH, PUT, DELETE, and HEAD requests with
       # +#post+, +#patch+, +#put+, +#delete+, and +#head+.
-      def get(path, parameters = nil, headers_or_env = nil)
-        process :get, path, parameters, headers_or_env
+      #
+      # Example:
+      #
+      #   get '/feed', params: { since: 201501011400 }
+      #   post '/profile', headers: { "X-Test-Header" => "testvalue" }
+      def get(path, *args)
+        process_with_kwargs(:get, path, *args)
       end
 
       # Performs a POST request with the given parameters. See +#get+ for more
       # details.
-      def post(path, parameters = nil, headers_or_env = nil)
-        process :post, path, parameters, headers_or_env
+      def post(path, *args)
+        process_with_kwargs(:post, path, *args)
       end
 
       # Performs a PATCH request with the given parameters. See +#get+ for more
       # details.
-      def patch(path, parameters = nil, headers_or_env = nil)
-        process :patch, path, parameters, headers_or_env
+      def patch(path, *args)
+        process_with_kwargs(:patch, path, *args)
       end
 
       # Performs a PUT request with the given parameters. See +#get+ for more
       # details.
-      def put(path, parameters = nil, headers_or_env = nil)
-        process :put, path, parameters, headers_or_env
+      def put(path, *args)
+        process_with_kwargs(:put, path, *args)
       end
 
       # Performs a DELETE request with the given parameters. See +#get+ for
       # more details.
-      def delete(path, parameters = nil, headers_or_env = nil)
-        process :delete, path, parameters, headers_or_env
+      def delete(path, *args)
+        process_with_kwargs(:delete, path, *args)
       end
 
       # Performs a HEAD request with the given parameters. See +#get+ for more
       # details.
-      def head(path, parameters = nil, headers_or_env = nil)
-        process :head, path, parameters, headers_or_env
+      def head(path, *args)
+        process_with_kwargs(:head, path, *args)
       end
 
       # Performs an XMLHttpRequest request with the given parameters, mirroring
@@ -68,11 +76,29 @@ module ActionDispatch
       # The request_method is +:get+, +:post+, +:patch+, +:put+, +:delete+ or
       # +:head+; the parameters are +nil+, a hash, or a url-encoded or multipart
       # string; the headers are a hash.
-      def xml_http_request(request_method, path, parameters = nil, headers_or_env = nil)
-        headers_or_env ||= {}
-        headers_or_env['HTTP_X_REQUESTED_WITH'] = 'XMLHttpRequest'
-        headers_or_env['HTTP_ACCEPT'] ||= [Mime::JS, Mime::HTML, Mime::XML, 'text/xml', Mime::ALL].join(', ')
-        process(request_method, path, parameters, headers_or_env)
+      #
+      # Example:
+      #
+      #   xhr :get, '/feed', params: { since: 201501011400 }
+      def xml_http_request(request_method, path, *args)
+        if kwarg_request?(args)
+          params, headers, env = args.first.values_at(:params, :headers, :env)
+        else
+          params = args[0]
+          headers = args[1]
+          env = {}
+
+          if params.present? || headers.present?
+            non_kwarg_request_warning
+          end
+        end
+
+        ActiveSupport::Deprecation.warn(<<-MSG.strip_heredoc)
+          xhr and xml_http_request methods are deprecated in favor of
+          `get "/posts", xhr: true` and `post "/posts/1", xhr: true`
+        MSG
+
+        process(request_method, path, params: params, headers: headers, xhr: true)
       end
       alias xhr :xml_http_request
 
@@ -89,40 +115,52 @@ module ActionDispatch
       # redirect. Note that the redirects are followed until the response is
       # not a redirect--this means you may run into an infinite loop if your
       # redirect loops back to itself.
-      def request_via_redirect(http_method, path, parameters = nil, headers_or_env = nil)
-        process(http_method, path, parameters, headers_or_env)
+      #
+      # Example:
+      #
+      #   request_via_redirect :post, '/welcome',
+      #     params: { ref_id: 14 },
+      #     headers: { "X-Test-Header" => "testvalue" }
+      def request_via_redirect(http_method, path, *args)
+        process_with_kwargs(http_method, path, *args)
+
         follow_redirect! while redirect?
         status
       end
 
       # Performs a GET request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
-      def get_via_redirect(path, parameters = nil, headers_or_env = nil)
-        request_via_redirect(:get, path, parameters, headers_or_env)
+      def get_via_redirect(path, *args)
+        ActiveSupport::Deprecation.warn('`get_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        request_via_redirect(:get, path, *args)
       end
 
       # Performs a POST request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
-      def post_via_redirect(path, parameters = nil, headers_or_env = nil)
-        request_via_redirect(:post, path, parameters, headers_or_env)
+      def post_via_redirect(path, *args)
+        ActiveSupport::Deprecation.warn('`post_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        request_via_redirect(:post, path, *args)
       end
 
       # Performs a PATCH request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
-      def patch_via_redirect(path, parameters = nil, headers_or_env = nil)
-        request_via_redirect(:patch, path, parameters, headers_or_env)
+      def patch_via_redirect(path, *args)
+        ActiveSupport::Deprecation.warn('`patch_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        request_via_redirect(:patch, path, *args)
       end
 
       # Performs a PUT request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
-      def put_via_redirect(path, parameters = nil, headers_or_env = nil)
-        request_via_redirect(:put, path, parameters, headers_or_env)
+      def put_via_redirect(path, *args)
+        ActiveSupport::Deprecation.warn('`put_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        request_via_redirect(:put, path, *args)
       end
 
       # Performs a DELETE request, following any subsequent redirect.
       # See +request_via_redirect+ for more information.
-      def delete_via_redirect(path, parameters = nil, headers_or_env = nil)
-        request_via_redirect(:delete, path, parameters, headers_or_env)
+      def delete_via_redirect(path, *args)
+        ActiveSupport::Deprecation.warn('`delete_via_redirect` is deprecated and will be removed in Rails 5.1. Please use follow_redirect! manually after the request call for the same behavior.')
+        request_via_redirect(:delete, path, *args)
       end
     end
 
@@ -185,15 +223,6 @@ module ActionDispatch
         super()
         @app = app
 
-        # If the app is a Rails app, make url_helpers available on the session
-        # This makes app.url_for and app.foo_path available in the console
-        if app.respond_to?(:routes)
-          singleton_class.class_eval do
-            include app.routes.url_helpers
-            include app.routes.mounted_helpers
-          end
-        end
-
         reset!
       end
 
@@ -261,20 +290,54 @@ module ActionDispatch
           @_mock_session ||= Rack::MockSession.new(@app, host)
         end
 
+        def process_with_kwargs(http_method, path, *args)
+          if kwarg_request?(args)
+            process(http_method, path, *args)
+          else
+            non_kwarg_request_warning if args.any?
+            process(http_method, path, { params: args[0], headers: args[1] })
+          end
+        end
+
+        REQUEST_KWARGS = %i(params headers env xhr)
+        def kwarg_request?(args)
+          args[0].respond_to?(:keys) && args[0].keys.any? { |k| REQUEST_KWARGS.include?(k) }
+        end
+
+        def non_kwarg_request_warning
+          ActiveSupport::Deprecation.warn(<<-MSG.strip_heredoc)
+            ActionDispatch::IntegrationTest HTTP request methods will accept only
+            the following keyword arguments in future Rails versions:
+            #{REQUEST_KWARGS.join(', ')}
+
+            Examples:
+
+            get '/profile',
+              params: { id: 1 },
+              headers: { 'X-Extra-Header' => '123' },
+              env: { 'action_dispatch.custom' => 'custom' },
+              xhr: true
+          MSG
+        end
+
         # Performs the actual request.
-        def process(method, path, parameters = nil, headers_or_env = nil)
+        def process(method, path, params: nil, headers: nil, env: nil, xhr: false)
           if path =~ %r{://}
             location = URI.parse(path)
             https! URI::HTTPS === location if location.scheme
-            host! "#{location.host}:#{location.port}" if location.host
+            if url_host = location.host
+              default = Rack::Request::DEFAULT_PORTS[location.scheme]
+              url_host += ":#{location.port}" if default != location.port
+              host! url_host
+            end
             path = location.query ? "#{location.path}?#{location.query}" : location.path
           end
 
           hostname, port = host.split(':')
 
-          env = {
+          request_env = {
             :method => method,
-            :params => parameters,
+            :params => params,
 
             "SERVER_NAME"     => hostname,
             "SERVER_PORT"     => port || (https? ? "443" : "80"),
@@ -287,25 +350,37 @@ module ActionDispatch
             "CONTENT_TYPE"   => "application/x-www-form-urlencoded",
             "HTTP_ACCEPT"    => accept
           }
-          # this modifies the passed env directly
-          Http::Headers.new(env).merge!(headers_or_env || {})
+
+          if xhr
+            headers ||= {}
+            headers['HTTP_X_REQUESTED_WITH'] = 'XMLHttpRequest'
+            headers['HTTP_ACCEPT'] ||= [Mime[:js], Mime[:html], Mime[:xml], 'text/xml', '*/*'].join(', ')
+          end
+
+          # this modifies the passed request_env directly
+          if headers.present?
+            Http::Headers.from_hash(request_env).merge!(headers)
+          end
+          if env.present?
+            Http::Headers.from_hash(request_env).merge!(env)
+          end
 
           session = Rack::Test::Session.new(_mock_session)
 
           # NOTE: rack-test v0.5 doesn't build a default uri correctly
           # Make sure requested path is always a full uri
-          session.request(build_full_uri(path, env), env)
+          session.request(build_full_uri(path, request_env), request_env)
 
           @request_count += 1
           @request  = ActionDispatch::Request.new(session.last_request.env)
           response = _mock_session.last_response
-          @response = ActionDispatch::TestResponse.new(response.status, response.headers, response.body)
+          @response = ActionDispatch::TestResponse.from_response(response)
           @html_document = nil
           @url_options = nil
 
-          @controller = session.last_request.env['action_controller.instance']
+          @controller = @request.controller_instance
 
-          return response.status
+          response.status
         end
 
         def build_full_uri(path, env)
@@ -316,14 +391,36 @@ module ActionDispatch
     module Runner
       include ActionDispatch::Assertions
 
-      def app
-        @app ||= nil
+      APP_SESSIONS = {}
+
+      attr_reader :app
+
+      def before_setup # :nodoc:
+        @app = nil
+        @integration_session = nil
+        super
+      end
+
+      def integration_session
+        @integration_session ||= create_session(app)
       end
 
       # Reset the current session. This is useful for testing multiple sessions
       # in a single test case.
       def reset!
-        @integration_session = Integration::Session.new(app)
+        @integration_session = create_session(app)
+      end
+
+      def create_session(app)
+        klass = APP_SESSIONS[app] ||= Class.new(Integration::Session) {
+          # If the app is a Rails app, make url_helpers available on the session
+          # This makes app.url_for and app.foo_path available in the console
+          if app.respond_to?(:routes)
+            include app.routes.url_helpers
+            include app.routes.mounted_helpers
+          end
+        }
+        klass.new(app)
       end
 
       def remove! # :nodoc:
@@ -333,12 +430,9 @@ module ActionDispatch
       %w(get post patch put head delete cookies assigns
          xml_http_request xhr get_via_redirect post_via_redirect).each do |method|
         define_method(method) do |*args|
-          reset! unless integration_session
-
           # reset the html_document variable, except for cookies/assigns calls
           unless method == 'cookies' || method == 'assigns'
             @html_document = nil
-            reset_template_assertion
           end
 
           integration_session.__send__(method, *args).tap do
@@ -366,19 +460,16 @@ module ActionDispatch
       # Copy the instance variables from the current session instance into the
       # test instance.
       def copy_session_variables! #:nodoc:
-        return unless integration_session
-        %w(controller response request).each do |var|
-          instance_variable_set("@#{var}", @integration_session.__send__(var))
-        end
+        @controller = @integration_session.controller
+        @response   = @integration_session.response
+        @request    = @integration_session.request
       end
 
       def default_url_options
-        reset! unless integration_session
         integration_session.default_url_options
       end
 
       def default_url_options=(options)
-        reset! unless integration_session
         integration_session.default_url_options = options
       end
 
@@ -388,7 +479,6 @@ module ActionDispatch
 
       # Delegate unhandled messages to the current session instance.
       def method_missing(sym, *args, &block)
-        reset! unless integration_session
         if integration_session.respond_to?(sym)
           integration_session.__send__(sym, *args, &block).tap do
             copy_session_variables!
@@ -397,11 +487,6 @@ module ActionDispatch
           super
         end
       end
-
-      private
-        def integration_session
-          @integration_session ||= nil
-        end
     end
   end
 
@@ -424,8 +509,8 @@ module ActionDispatch
   #       assert_equal 200, status
   #
   #       # post the login and follow through to the home page
-  #       post "/login", username: people(:jamis).username,
-  #         password: people(:jamis).password
+  #       post "/login", params: { username: people(:jamis).username,
+  #         password: people(:jamis).password }
   #       follow_redirect!
   #       assert_equal 200, status
   #       assert_equal "/home", path
@@ -464,7 +549,7 @@ module ActionDispatch
   #         end
   #
   #         def speak(room, message)
-  #           xml_http_request "/say/#{room.id}", message: message
+  #           post "/say/#{room.id}", xhr: true, params: { message: message }
   #           assert(...)
   #           ...
   #         end
@@ -474,8 +559,8 @@ module ActionDispatch
   #         open_session do |sess|
   #           sess.extend(CustomAssertions)
   #           who = people(who)
-  #           sess.post "/login", username: who.username,
-  #             password: who.password
+  #           sess.post "/login", params: { username: who.username,
+  #             password: who.password }
   #           assert(...)
   #         end
   #       end
@@ -494,14 +579,15 @@ module ActionDispatch
   #       get "/login"
   #       assert_response :success
   #
-  #       post_via_redirect "/login", username: users(:david).username, password: users(:david).password
+  #       post "/login", params: { username: users(:david).username, password: users(:david).password }
+  #       follow_redirect!
   #       assert_equal '/welcome', path
   #       assert_equal 'Welcome david!', flash[:notice]
   #
   #       https!(false)
   #       get "/articles/all"
   #       assert_response :success
-  #       assert assigns(:articles)
+  #       assert_select 'h1', 'Articles'
   #     end
   #   end
   #
@@ -540,7 +626,7 @@ module ActionDispatch
   #         def browses_site
   #           get "/products/all"
   #           assert_response :success
-  #           assert assigns(:products)
+  #           assert_select 'h1', 'Products'
   #         end
   #       end
   #
@@ -549,7 +635,7 @@ module ActionDispatch
   #           sess.extend(CustomDsl)
   #           u = users(user)
   #           sess.https!
-  #           sess.post "/login", username: u.username, password: u.password
+  #           sess.post "/login", params: { username: u.username, password: u.password }
   #           assert_equal '/welcome', sess.path
   #           sess.https!(false)
   #         end
@@ -578,7 +664,6 @@ module ActionDispatch
     end
 
     def url_options
-      reset! unless integration_session
       integration_session.url_options
     end
 
diff --git a/actionpack/lib/action_dispatch/testing/test_process.rb b/actionpack/lib/action_dispatch/testing/test_process.rb
index 630e6a9b78..c28d701b48 100644
--- a/actionpack/lib/action_dispatch/testing/test_process.rb
+++ b/actionpack/lib/action_dispatch/testing/test_process.rb
@@ -5,9 +5,9 @@ require 'active_support/core_ext/hash/indifferent_access'
 module ActionDispatch
   module TestProcess
     def assigns(key = nil)
-      assigns = {}.with_indifferent_access
-      @controller.view_assigns.each { |k, v| assigns.regular_writer(k, v) }
-      key.nil? ? assigns : assigns[key]
+      raise NoMethodError,
+        "assigns has been extracted to a gem. To continue using it,
+        add `gem 'rails-controller-testing'` to your Gemfile."
     end
 
     def session
@@ -19,7 +19,7 @@ module ActionDispatch
     end
 
     def cookies
-      @request.cookie_jar
+      @cookie_jar ||= Cookies::CookieJar.build(@request, @request.cookies)
     end
 
     def redirect_to_url
diff --git a/actionpack/lib/action_dispatch/testing/test_request.rb b/actionpack/lib/action_dispatch/testing/test_request.rb
index 4b9a088265..ad1a7f7109 100644
--- a/actionpack/lib/action_dispatch/testing/test_request.rb
+++ b/actionpack/lib/action_dispatch/testing/test_request.rb
@@ -4,19 +4,22 @@ require 'rack/utils'
 module ActionDispatch
   class TestRequest < Request
     DEFAULT_ENV = Rack::MockRequest.env_for('/',
-      'HTTP_HOST'       => 'test.host',
-      'REMOTE_ADDR'     => '0.0.0.0',
-      'HTTP_USER_AGENT' => 'Rails Testing'
+      'HTTP_HOST'                => 'test.host',
+      'REMOTE_ADDR'              => '0.0.0.0',
+      'HTTP_USER_AGENT'          => 'Rails Testing',
     )
 
-    def self.new(env = {})
-      super
+    # Create a new test request with default `env` values
+    def self.create(env = {})
+      env = Rails.application.env_config.merge(env) if defined?(Rails.application) && Rails.application
+      env["rack.request.cookie_hash"] ||= {}.with_indifferent_access
+      new(default_env.merge(env))
     end
 
-    def initialize(env = {})
-      env = Rails.application.env_config.merge(env) if defined?(Rails.application) && Rails.application
-      super(default_env.merge(env))
+    def self.default_env
+      DEFAULT_ENV
     end
+    private_class_method :default_env
 
     def request_method=(method)
       @env['REQUEST_METHOD'] = method.to_s.upcase
@@ -62,17 +65,5 @@ module ActionDispatch
       @env.delete('action_dispatch.request.accepts')
       @env['HTTP_ACCEPT'] = Array(mime_types).collect(&:to_s).join(",")
     end
-
-    alias :rack_cookies :cookies
-
-    def cookies
-      @cookies ||= {}.with_indifferent_access
-    end
-
-    private
-
-    def default_env
-      DEFAULT_ENV
-    end
   end
 end
diff --git a/actionpack/lib/action_dispatch/testing/test_response.rb b/actionpack/lib/action_dispatch/testing/test_response.rb
index 369ea1467c..4b79a90242 100644
--- a/actionpack/lib/action_dispatch/testing/test_response.rb
+++ b/actionpack/lib/action_dispatch/testing/test_response.rb
@@ -7,11 +7,7 @@ module ActionDispatch
   # See Response for more information on controller response objects.
   class TestResponse < Response
     def self.from_response(response)
-      new.tap do |resp|
-        resp.status  = response.status
-        resp.headers = response.headers
-        resp.body    = response.body
-      end
+      new response.status, response.headers, response.body
     end
 
     # Was the response successful?
@@ -20,17 +16,7 @@ module ActionDispatch
     # Was the URL not found?
     alias_method :missing?, :not_found?
 
-    # Were we redirected?
-    alias_method :redirect?, :redirection?
-
     # Was there a server-side error?
     alias_method :error?, :server_error?
-
-    def merge_default_headers(original, *args)
-      # Default headers are already applied, no need to merge them a second time.
-      # This makes sure that default headers, removed in controller actions, will
-      # not be reapplied to the test response.
-      original
-    end
   end
 end
diff --git a/actionpack/test/abstract/collector_test.rb b/actionpack/test/abstract/collector_test.rb
index fc59bf19c4..edbb84d462 100644
--- a/actionpack/test/abstract/collector_test.rb
+++ b/actionpack/test/abstract/collector_test.rb
@@ -53,9 +53,9 @@ module AbstractController
         collector.html
         collector.text(:foo)
         collector.js(:bar) { :baz }
-        assert_equal [Mime::HTML, [], nil], collector.responses[0]
-        assert_equal [Mime::TEXT, [:foo], nil], collector.responses[1]
-        assert_equal [Mime::JS, [:bar]], collector.responses[2][0,2]
+        assert_equal [Mime[:html], [], nil], collector.responses[0]
+        assert_equal [Mime[:text], [:foo], nil], collector.responses[1]
+        assert_equal [Mime[:js], [:bar]], collector.responses[2][0,2]
         assert_equal :baz, collector.responses[2][2].call
       end
     end
diff --git a/actionpack/test/abstract/translation_test.rb b/actionpack/test/abstract/translation_test.rb
index 4fdc480b43..1435928578 100644
--- a/actionpack/test/abstract/translation_test.rb
+++ b/actionpack/test/abstract/translation_test.rb
@@ -9,6 +9,21 @@ module AbstractController
     class TranslationControllerTest < ActiveSupport::TestCase
       def setup
         @controller = TranslationController.new
+        I18n.backend.store_translations(:en, {
+          one: {
+            two: 'bar',
+          },
+          abstract_controller: {
+            testing: {
+              translation: {
+                index: {
+                  foo: 'bar',
+                },
+                no_action: 'no_action_tr',
+              },
+            },
+          },
+        })
       end
 
       def test_action_controller_base_responds_to_translate
@@ -28,22 +43,34 @@ module AbstractController
       end
 
       def test_lazy_lookup
-        expected = 'bar'
-        @controller.stubs(action_name: :index)
-        I18n.stubs(:translate).with('abstract_controller.testing.translation.index.foo').returns(expected)
-        assert_equal expected, @controller.t('.foo')
+        @controller.stub :action_name, :index do
+          assert_equal 'bar', @controller.t('.foo')
+        end
+      end
+
+      def test_lazy_lookup_with_symbol
+        @controller.stub :action_name, :index do
+          assert_equal 'bar', @controller.t(:'.foo')
+        end
+      end
+
+      def test_lazy_lookup_fallback
+        @controller.stub :action_name, :index do
+          assert_equal 'no_action_tr', @controller.t(:'.no_action')
+        end
       end
 
       def test_default_translation
-        key, expected = 'one.two', 'bar'
-        I18n.stubs(:translate).with(key).returns(expected)
-        assert_equal expected, @controller.t(key)
+        @controller.stub :action_name, :index do
+          assert_equal 'bar', @controller.t('one.two')
+        end
       end
 
       def test_localize
         time, expected = Time.gm(2000), 'Sat, 01 Jan 2000 00:00:00 +0000'
-        I18n.stubs(:localize).with(time).returns(expected)
-        assert_equal expected, @controller.l(time)
+        I18n.stub :localize, expected do
+          assert_equal expected, @controller.l(time)
+        end
       end
     end
   end
diff --git a/actionpack/test/abstract_unit.rb b/actionpack/test/abstract_unit.rb
index 2d69ceed3a..ef7aab72c6 100644
--- a/actionpack/test/abstract_unit.rb
+++ b/actionpack/test/abstract_unit.rb
@@ -14,8 +14,11 @@ silence_warnings do
 end
 
 require 'drb'
-require 'drb/unix'
-require 'tempfile'
+begin
+  require 'drb/unix'
+rescue LoadError
+  puts "'drb/unix' is not available"
+end
 
 PROCESS_COUNT = (ENV['N'] || 4).to_i
 
@@ -38,6 +41,8 @@ module Rails
     def env
       @_env ||= ActiveSupport::StringInquirer.new(ENV["RAILS_ENV"] || ENV["RACK_ENV"] || "test")
     end
+
+    def root; end;
   end
 end
 
@@ -54,26 +59,15 @@ I18n.enforce_available_locales = false
 # Register danish language for testing
 I18n.backend.store_translations 'da', {}
 I18n.backend.store_translations 'pt-BR', {}
-ORIGINAL_LOCALES = I18n.available_locales.map(&:to_s).sort
 
 FIXTURE_LOAD_PATH = File.join(File.dirname(__FILE__), 'fixtures')
-FIXTURES = Pathname.new(FIXTURE_LOAD_PATH)
-
-module RackTestUtils
-  def body_to_string(body)
-    if body.respond_to?(:each)
-      str = ""
-      body.each {|s| str << s }
-      str
-    else
-      body
-    end
-  end
-  extend self
-end
 
 SharedTestRoutes = ActionDispatch::Routing::RouteSet.new
 
+SharedTestRoutes.draw do
+  get ':controller(/:action)'
+end
+
 module ActionDispatch
   module SharedRoutes
     def before_setup
@@ -81,36 +75,11 @@ module ActionDispatch
       super
     end
   end
-
-  # Hold off drawing routes until all the possible controller classes
-  # have been loaded.
-  module DrawOnce
-    class << self
-      attr_accessor :drew
-    end
-    self.drew = false
-
-    def before_setup
-      super
-      return if DrawOnce.drew
-
-      SharedTestRoutes.draw do
-        get ':controller(/:action)'
-      end
-
-      ActionDispatch::IntegrationTest.app.routes.draw do
-        get ':controller(/:action)'
-      end
-
-      DrawOnce.drew = true
-    end
-  end
 end
 
 module ActiveSupport
   class TestCase
-    include ActionDispatch::DrawOnce
-    if ActiveSupport::Testing::Isolation.forking_env? && PROCESS_COUNT > 0
+    if RUBY_ENGINE == "ruby" && PROCESS_COUNT > 0
       parallelize_me!
     end
   end
@@ -129,61 +98,55 @@ class RoutedRackApp
   end
 end
 
-class BasicController
-  attr_accessor :request
-
-  def config
-    @config ||= ActiveSupport::InheritableOptions.new(ActionController::Base.config).tap do |config|
-      # VIEW TODO: View tests should not require a controller
-      public_dir = File.expand_path("../fixtures/public", __FILE__)
-      config.assets_dir = public_dir
-      config.javascripts_dir = "#{public_dir}/javascripts"
-      config.stylesheets_dir = "#{public_dir}/stylesheets"
-      config.assets          = ActiveSupport::InheritableOptions.new({ :prefix => "assets" })
-      config
-    end
-  end
-end
-
 class ActionDispatch::IntegrationTest < ActiveSupport::TestCase
-  include ActionDispatch::SharedRoutes
-
   def self.build_app(routes = nil)
     RoutedRackApp.new(routes || ActionDispatch::Routing::RouteSet.new) do |middleware|
-      middleware.use "ActionDispatch::ShowExceptions", ActionDispatch::PublicExceptions.new("#{FIXTURE_LOAD_PATH}/public")
-      middleware.use "ActionDispatch::DebugExceptions"
-      middleware.use "ActionDispatch::Callbacks"
-      middleware.use "ActionDispatch::ParamsParser"
-      middleware.use "ActionDispatch::Cookies"
-      middleware.use "ActionDispatch::Flash"
-      middleware.use "Rack::Head"
+      middleware.use ActionDispatch::ShowExceptions, ActionDispatch::PublicExceptions.new("#{FIXTURE_LOAD_PATH}/public")
+      middleware.use ActionDispatch::DebugExceptions
+      middleware.use ActionDispatch::Callbacks
+      middleware.use ActionDispatch::Cookies
+      middleware.use ActionDispatch::Flash
+      middleware.use Rack::Head
       yield(middleware) if block_given?
     end
   end
 
   self.app = build_app
 
-  # Stub Rails dispatcher so it does not get controller references and
-  # simply return the controller#action as Rack::Body.
-  class StubDispatcher < ::ActionDispatch::Routing::RouteSet::Dispatcher
-    protected
-    def controller_reference(controller_param)
-      controller_param
+  app.routes.draw do
+    get ':controller(/:action)'
+  end
+
+  class DeadEndRoutes < ActionDispatch::Routing::RouteSet
+    # Stub Rails dispatcher so it does not get controller references and
+    # simply return the controller#action as Rack::Body.
+    class NullController < ::ActionController::Metal
+      def initialize(controller_name)
+        @controller = controller_name
+      end
+
+      def make_response!(request)
+        self.class.make_response! request
+      end
+
+      def dispatch(action, req, res)
+        [200, {'Content-Type' => 'text/html'}, ["#{@controller}##{action}"]]
+      end
+    end
+
+    class NullControllerRequest < DelegateClass(ActionDispatch::Request)
+      def controller_class
+        NullController.new params[:controller]
+      end
     end
 
-    def dispatch(controller, action, env)
-      [200, {'Content-Type' => 'text/html'}, ["#{controller}##{action}"]]
+    def make_request env
+      NullControllerRequest.new super
     end
   end
 
-  def self.stub_controllers
-    old_dispatcher = ActionDispatch::Routing::RouteSet::Dispatcher
-    ActionDispatch::Routing::RouteSet.module_eval { remove_const :Dispatcher }
-    ActionDispatch::Routing::RouteSet.module_eval { const_set :Dispatcher, StubDispatcher }
-    yield ActionDispatch::Routing::RouteSet.new
-  ensure
-    ActionDispatch::Routing::RouteSet.module_eval { remove_const :Dispatcher }
-    ActionDispatch::Routing::RouteSet.module_eval { const_set :Dispatcher, old_dispatcher }
+  def self.stub_controllers(config = ActionDispatch::Routing::RouteSet::DEFAULT_CONFIG)
+    yield DeadEndRoutes.new(config)
   end
 
   def with_routing(&block)
@@ -259,6 +222,10 @@ class Rack::TestCase < ActionDispatch::IntegrationTest
 end
 
 module ActionController
+  class API
+    extend AbstractController::Railties::RoutesHelpers.with(SharedTestRoutes)
+  end
+
   class Base
     # This stub emulates the Railtie including the URL helpers from a Rails application
     extend AbstractController::Railties::RoutesHelpers.with(SharedTestRoutes)
@@ -369,45 +336,43 @@ module RoutingTestHelpers
   end
 
   class TestSet < ActionDispatch::Routing::RouteSet
-    attr_reader :strict
-
-    def initialize(block, strict = false)
-      @block = block
-      @strict = strict
-      super()
-    end
-
-    class Dispatcher < ActionDispatch::Routing::RouteSet::Dispatcher
-      def initialize(defaults, set, block)
-        super(defaults)
+    class Request < DelegateClass(ActionDispatch::Request)
+      def initialize(target, helpers, block, strict)
+        super(target)
+        @helpers = helpers
         @block = block
-        @set = set
-      end
-
-      def controller(params, default_controller=true)
-        super(params, @set.strict)
+        @strict = strict
       end
 
-      def controller_reference(controller_param)
+      def controller_class
+        helpers = @helpers
         block = @block
-        set = @set
-        super if @set.strict
-        Class.new(ActionController::Base) {
-          include set.url_helpers
+        Class.new(@strict ? super : ActionController::Base) {
+          include helpers
           define_method(:process) { |name| block.call(self) }
           def to_a; [200, {}, []]; end
         }
       end
     end
 
-    def dispatcher defaults
-      TestSet::Dispatcher.new defaults, self, @block
+    attr_reader :strict
+
+    def initialize(block, strict = false)
+      @block = block
+      @strict = strict
+      super()
+    end
+
+    private
+
+    def make_request(env)
+      Request.new super, url_helpers, @block, strict
     end
   end
 end
 
 class ResourcesController < ActionController::Base
-  def index() render :nothing => true end
+  def index() head :ok end
   alias_method :show, :index
 end
 
@@ -415,13 +380,11 @@ class ThreadsController  < ResourcesController; end
 class MessagesController < ResourcesController; end
 class CommentsController < ResourcesController; end
 class ReviewsController < ResourcesController; end
-class LogosController < ResourcesController; end
 
 class AccountsController <  ResourcesController; end
 class AdminController   <  ResourcesController; end
 class ProductsController < ResourcesController; end
 class ImagesController < ResourcesController; end
-class PreferencesController < ResourcesController; end
 
 module Backoffice
   class ProductsController < ResourcesController; end
@@ -442,7 +405,7 @@ def jruby_skip(message = '')
   skip message if defined?(JRUBY_VERSION)
 end
 
-require 'mocha/setup' # FIXME: stop using mocha
+require 'active_support/testing/method_call_assertions'
 
 class ForkingExecutor
   class Server
@@ -510,12 +473,11 @@ class ForkingExecutor
   end
 end
 
-if ActiveSupport::Testing::Isolation.forking_env? && PROCESS_COUNT > 0
+if RUBY_ENGINE == "ruby" && PROCESS_COUNT > 0
   # Use N processes (N defaults to 4)
   Minitest.parallel_executor = ForkingExecutor.new(PROCESS_COUNT)
 end
 
-# FIXME: we have tests that depend on run order, we should fix that and
-# remove this method call.
-require 'active_support/test_case'
-ActiveSupport::TestCase.test_order = :sorted
+class ActiveSupport::TestCase
+  include ActiveSupport::Testing::MethodCallAssertions
+end
diff --git a/actionpack/test/assertions/response_assertions_test.rb b/actionpack/test/assertions/response_assertions_test.rb
index 5e64cae7e2..82c747680d 100644
--- a/actionpack/test/assertions/response_assertions_test.rb
+++ b/actionpack/test/assertions/response_assertions_test.rb
@@ -7,7 +7,7 @@ module ActionDispatch
       include ResponseAssertions
 
       FakeResponse = Struct.new(:response_code) do
-        [:success, :missing, :redirect, :error].each do |sym|
+        [:successful, :not_found, :redirection, :server_error].each do |sym|
           define_method("#{sym}?") do
             sym == response_code
           end
@@ -16,7 +16,7 @@ module ActionDispatch
 
       def test_assert_response_predicate_methods
         [:success, :missing, :redirect, :error].each do |sym|
-          @response = FakeResponse.new sym
+          @response = FakeResponse.new RESPONSE_PREDICATES[sym].to_s.sub(/\?/, '').to_sym
           assert_response sym
 
           assert_raises(Minitest::Assertion) {
diff --git a/actionpack/test/controller/action_pack_assertions_test.rb b/actionpack/test/controller/action_pack_assertions_test.rb
index d0dfbfbc74..899d92f815 100644
--- a/actionpack/test/controller/action_pack_assertions_test.rb
+++ b/actionpack/test/controller/action_pack_assertions_test.rb
@@ -5,9 +5,6 @@ class ActionPackAssertionsController < ActionController::Base
 
   def nothing() head :ok end
 
-  def hello_world() render :template => "test/hello_world"; end
-  def hello_repeating_in_path() render :template => "test/hello/hello"; end
-
   def hello_xml_world() render :template => "test/hello_xml_world"; end
 
   def hello_xml_world_pdf
@@ -20,8 +17,6 @@ class ActionPackAssertionsController < ActionController::Base
     render :template => "test/hello_xml_world"
   end
 
-  def partial() render :partial => 'test/partial'; end
-
   def redirect_internal() redirect_to "/nothing"; end
 
   def redirect_to_action() redirect_to :action => "flash_me", :id => 1, :params => { "panda" => "fun" }; end
@@ -48,12 +43,12 @@ class ActionPackAssertionsController < ActionController::Base
 
   def flash_me
     flash['hello'] = 'my name is inigo montoya...'
-    render :text => "Inconceivable!"
+    render plain: "Inconceivable!"
   end
 
   def flash_me_naked
     flash.clear
-    render :text => "wow!"
+    render plain: "wow!"
   end
 
   def assign_this
@@ -62,40 +57,30 @@ class ActionPackAssertionsController < ActionController::Base
   end
 
   def render_based_on_parameters
-    render :text => "Mr. #{params[:name]}"
+    render plain: "Mr. #{params[:name]}"
   end
 
   def render_url
-    render :text => "<div>#{url_for(:action => 'flash_me', :only_path => true)}</div>"
+    render html: "<div>#{url_for(action: 'flash_me', only_path: true)}</div>"
   end
 
   def render_text_with_custom_content_type
-    render :text => "Hello!", :content_type => Mime::RSS
-  end
-
-  def render_with_layout
-    @variable_for_layout = nil
-    render "test/hello_world", :layout => "layouts/standard"
-  end
-
-  def render_with_layout_and_partial
-    @variable_for_layout = nil
-    render "test/hello_world_with_partial", :layout => "layouts/standard"
+    render body: "Hello!", content_type: Mime[:rss]
   end
 
   def session_stuffing
     session['xmas'] = 'turkey'
-    render :text => "ho ho ho"
+    render plain: "ho ho ho"
   end
 
   def raise_exception_on_get
     raise "get" if request.get?
-    render :text => "request method: #{request.env['REQUEST_METHOD']}"
+    render plain: "request method: #{request.env['REQUEST_METHOD']}"
   end
 
   def raise_exception_on_post
     raise "post" if request.post?
-    render :text => "request method: #{request.env['REQUEST_METHOD']}"
+    render plain: "request method: #{request.env['REQUEST_METHOD']}"
   end
 
   def render_file_absolute_path
@@ -116,14 +101,14 @@ class AssertResponseWithUnexpectedErrorController < ActionController::Base
   end
 
   def show
-    render :text => "Boom", :status => 500
+    render plain: "Boom", status: 500
   end
 end
 
 module Admin
   class InnerModuleController < ActionController::Base
     def index
-      render :nothing => true
+      head :ok
     end
 
     def redirect_to_index
@@ -304,14 +289,6 @@ class ActionPackAssertionsControllerTest < ActionController::TestCase
     assert session.empty?
   end
 
-  def test_render_template_action
-    process :nothing
-    assert_template nil
-
-    process :hello_world
-    assert_template 'hello_world'
-  end
-
   def test_redirection_location
     process :redirect_internal
     assert_equal 'http://test.host/nothing', @response.redirect_url
@@ -341,7 +318,7 @@ class ActionPackAssertionsControllerTest < ActionController::TestCase
 
   def test_missing_response_code
     process :response404
-    assert @response.missing?
+    assert @response.not_found?
   end
 
   def test_client_error_response_code
@@ -369,16 +346,18 @@ class ActionPackAssertionsControllerTest < ActionController::TestCase
 
   def test_successful_response_code
     process :nothing
-    assert @response.success?
+    assert @response.successful?
   end
 
   def test_response_object
     process :nothing
-    assert_kind_of ActionController::TestResponse, @response
+    assert_kind_of ActionDispatch::TestResponse, @response
   end
 
   def test_render_based_on_parameters
-    process :render_based_on_parameters, "GET", "name" => "David"
+    process :render_based_on_parameters,
+      method: "GET",
+      params: { name: "David" }
     assert_equal "Mr. David", @response.body
   end
 
@@ -453,192 +432,6 @@ class ActionPackAssertionsControllerTest < ActionController::TestCase
   end
 end
 
-class AssertTemplateTest < ActionController::TestCase
-  tests ActionPackAssertionsController
-
-  def test_with_invalid_hash_keys_raises_argument_error
-    assert_raise(ArgumentError) do
-      assert_template foo: "bar"
-    end
-  end
-
-  def test_with_partial
-    get :partial
-    assert_template :partial => '_partial'
-  end
-
-  def test_file_with_absolute_path_success
-    get :render_file_absolute_path
-    assert_template :file => File.expand_path('../../../README.rdoc', __FILE__)
-  end
-
-  def test_file_with_relative_path_success
-    get :render_file_relative_path
-    assert_template :file => 'README.rdoc'
-  end
-
-  def test_with_file_failure
-    get :render_file_absolute_path
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template :file => 'test/hello_world'
-    end
-
-    get :render_file_absolute_path
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template file: nil
-    end
-  end
-
-  def test_with_nil_passes_when_no_template_rendered
-    get :nothing
-    assert_template nil
-  end
-
-  def test_with_nil_fails_when_template_rendered
-    get :hello_world
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template nil
-    end
-  end
-
-  def test_with_empty_string_fails_when_template_rendered
-    get :hello_world
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template ""
-    end
-  end
-
-  def test_with_empty_string_fails_when_no_template_rendered
-    get :nothing
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template ""
-    end
-  end
-
-  def test_passes_with_correct_string
-    get :hello_world
-    assert_template 'hello_world'
-    assert_template 'test/hello_world'
-  end
-
-  def test_passes_with_correct_symbol
-    get :hello_world
-    assert_template :hello_world
-  end
-
-  def test_fails_with_incorrect_string
-    get :hello_world
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template 'hello_planet'
-    end
-  end
-
-  def test_fails_with_incorrect_string_that_matches
-    get :hello_world
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template 'est/he'
-    end
-  end
-
-  def test_fails_with_repeated_name_in_path
-    get :hello_repeating_in_path
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template 'test/hello'
-    end
-  end
-
-  def test_fails_with_incorrect_symbol
-    get :hello_world
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template :hello_planet
-    end
-  end
-
-  def test_fails_with_incorrect_symbol_that_matches
-    get :hello_world
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template :"est/he"
-    end
-  end
-
-  def test_fails_with_wrong_layout
-    get :render_with_layout
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template :layout => "application"
-    end
-  end
-
-  def test_fails_expecting_no_layout
-    get :render_with_layout
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template :layout => nil
-    end
-  end
-
-  def test_fails_expecting_not_known_layout
-    get :render_with_layout
-    assert_raise(ArgumentError) do
-      assert_template :layout => 1
-    end
-  end
-
-  def test_passes_with_correct_layout
-    get :render_with_layout
-    assert_template :layout => "layouts/standard"
-  end
-
-  def test_passes_with_layout_and_partial
-    get :render_with_layout_and_partial
-    assert_template :layout => "layouts/standard"
-  end
-
-  def test_passed_with_no_layout
-    get :hello_world
-    assert_template :layout => nil
-  end
-
-  def test_passed_with_no_layout_false
-    get :hello_world
-    assert_template :layout => false
-  end
-
-  def test_passes_with_correct_layout_without_layouts_prefix
-    get :render_with_layout
-    assert_template :layout => "standard"
-  end
-
-  def test_passes_with_correct_layout_symbol
-    get :render_with_layout
-    assert_template :layout => :standard
-  end
-
-  def test_assert_template_reset_between_requests
-    get :hello_world
-    assert_template 'test/hello_world'
-
-    get :nothing
-    assert_template nil
-
-    get :partial
-    assert_template partial: 'test/_partial'
-
-    get :nothing
-    assert_template partial: nil
-
-    get :render_with_layout
-    assert_template layout: 'layouts/standard'
-
-    get :nothing
-    assert_template layout: nil
-
-    get :render_file_relative_path
-    assert_template file: 'README.rdoc'
-
-    get :nothing
-    assert_template file: nil
-  end
-end
-
 class ActionPackHeaderTest < ActionController::TestCase
   tests ActionPackAssertionsController
 
diff --git a/actionpack/test/controller/api/conditional_get_test.rb b/actionpack/test/controller/api/conditional_get_test.rb
new file mode 100644
index 0000000000..b4f1673be0
--- /dev/null
+++ b/actionpack/test/controller/api/conditional_get_test.rb
@@ -0,0 +1,57 @@
+require 'abstract_unit'
+require 'active_support/core_ext/integer/time'
+require 'active_support/core_ext/numeric/time'
+
+class ConditionalGetApiController < ActionController::API
+  before_action :handle_last_modified_and_etags, only: :two
+
+  def one
+    if stale?(last_modified: Time.now.utc.beginning_of_day, etag: [:foo, 123])
+      render plain: "Hi!"
+    end
+  end
+
+  def two
+    render plain: "Hi!"
+  end
+
+  private
+
+  def handle_last_modified_and_etags
+    fresh_when(last_modified: Time.now.utc.beginning_of_day, etag: [ :foo, 123 ])
+  end
+end
+
+class ConditionalGetApiTest < ActionController::TestCase
+  tests ConditionalGetApiController
+
+  def setup
+    @last_modified = Time.now.utc.beginning_of_day.httpdate
+  end
+
+  def test_request_gets_last_modified
+    get :two
+    assert_equal @last_modified, @response.headers['Last-Modified']
+    assert_response :success
+  end
+
+  def test_request_obeys_last_modified
+    @request.if_modified_since = @last_modified
+    get :two
+    assert_response :not_modified
+  end
+
+  def test_last_modified_works_with_less_than_too
+    @request.if_modified_since = 5.years.ago.httpdate
+    get :two
+    assert_response :success
+  end
+
+  def test_request_not_modified
+    @request.if_modified_since = @last_modified
+    get :one
+    assert_equal 304, @response.status.to_i
+    assert @response.body.blank?
+    assert_equal @last_modified, @response.headers['Last-Modified']
+  end
+end
diff --git a/actionpack/test/controller/api/data_streaming_test.rb b/actionpack/test/controller/api/data_streaming_test.rb
new file mode 100644
index 0000000000..0e7d97d1f4
--- /dev/null
+++ b/actionpack/test/controller/api/data_streaming_test.rb
@@ -0,0 +1,26 @@
+require 'abstract_unit'
+
+module TestApiFileUtils
+  def file_path() File.expand_path(__FILE__) end
+  def file_data() @data ||= File.open(file_path, 'rb') { |f| f.read } end
+end
+
+class DataStreamingApiController < ActionController::API
+  include TestApiFileUtils
+
+  def one; end
+  def two
+    send_data(file_data, {})
+  end
+end
+
+class DataStreamingApiTest < ActionController::TestCase
+  include TestApiFileUtils
+  tests DataStreamingApiController
+
+  def test_data
+    response = process('two')
+    assert_kind_of String, response.body
+    assert_equal file_data, response.body
+  end
+end
diff --git a/actionpack/test/controller/api/force_ssl_test.rb b/actionpack/test/controller/api/force_ssl_test.rb
new file mode 100644
index 0000000000..8578340d82
--- /dev/null
+++ b/actionpack/test/controller/api/force_ssl_test.rb
@@ -0,0 +1,20 @@
+require 'abstract_unit'
+
+class ForceSSLApiController < ActionController::API
+  force_ssl
+
+  def one; end
+  def two
+    head :ok
+  end
+end
+
+class ForceSSLApiTest < ActionController::TestCase
+  tests ForceSSLApiController
+
+  def test_redirects_to_https
+    get :two
+    assert_response 301
+    assert_equal "https://test.host/force_ssl_api/two", redirect_to_url
+  end
+end
diff --git a/actionpack/test/controller/api/implicit_render_test.rb b/actionpack/test/controller/api/implicit_render_test.rb
new file mode 100644
index 0000000000..26f9cd8f78
--- /dev/null
+++ b/actionpack/test/controller/api/implicit_render_test.rb
@@ -0,0 +1,15 @@
+require 'abstract_unit'
+
+class ImplicitRenderAPITestController < ActionController::API
+  def empty_action
+  end
+end
+
+class ImplicitRenderAPITest < ActionController::TestCase
+  tests ImplicitRenderAPITestController
+
+  def test_implicit_no_content_response
+    get :empty_action
+    assert_response :no_content
+  end
+end
diff --git a/actionpack/test/controller/api/params_wrapper_test.rb b/actionpack/test/controller/api/params_wrapper_test.rb
new file mode 100644
index 0000000000..53b3a0c3cc
--- /dev/null
+++ b/actionpack/test/controller/api/params_wrapper_test.rb
@@ -0,0 +1,26 @@
+require 'abstract_unit'
+
+class ParamsWrapperForApiTest < ActionController::TestCase
+  class UsersController < ActionController::API
+    attr_accessor :last_parameters
+
+    wrap_parameters :person, format: [:json]
+
+    def test
+      self.last_parameters = params.except(:controller, :action).to_unsafe_h
+      head :ok
+    end
+  end
+
+  class Person; end
+
+  tests UsersController
+
+  def test_specify_wrapper_name
+    @request.env['CONTENT_TYPE'] = 'application/json'
+    post :test, params: { 'username' => 'sikachu' }
+
+    expected = { 'username' => 'sikachu', 'person' => { 'username' => 'sikachu' }}
+    assert_equal expected, @controller.last_parameters
+  end
+end
diff --git a/actionpack/test/controller/api/redirect_to_test.rb b/actionpack/test/controller/api/redirect_to_test.rb
new file mode 100644
index 0000000000..18877c4b3a
--- /dev/null
+++ b/actionpack/test/controller/api/redirect_to_test.rb
@@ -0,0 +1,19 @@
+require 'abstract_unit'
+
+class RedirectToApiController < ActionController::API
+  def one
+    redirect_to action: "two"
+  end
+
+  def two; end
+end
+
+class RedirectToApiTest < ActionController::TestCase
+  tests RedirectToApiController
+
+  def test_redirect_to
+    get :one
+    assert_response :redirect
+    assert_equal "http://test.host/redirect_to_api/two", redirect_to_url
+  end
+end
diff --git a/actionpack/test/controller/api/renderers_test.rb b/actionpack/test/controller/api/renderers_test.rb
new file mode 100644
index 0000000000..9405538833
--- /dev/null
+++ b/actionpack/test/controller/api/renderers_test.rb
@@ -0,0 +1,38 @@
+require 'abstract_unit'
+require 'active_support/core_ext/hash/conversions'
+
+class RenderersApiController < ActionController::API
+  class Model
+    def to_json(options = {})
+      { a: 'b' }.to_json(options)
+    end
+
+    def to_xml(options = {})
+      { a: 'b' }.to_xml(options)
+    end
+  end
+
+  def one
+    render json: Model.new
+  end
+
+  def two
+    render xml: Model.new
+  end
+end
+
+class RenderersApiTest < ActionController::TestCase
+  tests RenderersApiController
+
+  def test_render_json
+    get :one
+    assert_response :success
+    assert_equal({ a: 'b' }.to_json, @response.body)
+  end
+
+  def test_render_xml
+    get :two
+    assert_response :success
+    assert_equal({ a: 'b' }.to_xml, @response.body)
+  end
+end
diff --git a/actionpack/test/controller/api/url_for_test.rb b/actionpack/test/controller/api/url_for_test.rb
new file mode 100644
index 0000000000..0d8691a091
--- /dev/null
+++ b/actionpack/test/controller/api/url_for_test.rb
@@ -0,0 +1,20 @@
+require 'abstract_unit'
+
+class UrlForApiController < ActionController::API
+  def one; end
+  def two; end
+end
+
+class UrlForApiTest < ActionController::TestCase
+  tests UrlForApiController
+
+  def setup
+    super
+    @request.host = 'www.example.com'
+  end
+
+  def test_url_for
+    get :one
+    assert_equal "http://www.example.com/url_for_api/one", @controller.url_for
+  end
+end
diff --git a/actionpack/test/controller/base_test.rb b/actionpack/test/controller/base_test.rb
index 001493afc0..fb60dbd993 100644
--- a/actionpack/test/controller/base_test.rb
+++ b/actionpack/test/controller/base_test.rb
@@ -13,7 +13,7 @@ end
 
 class NonEmptyController < ActionController::Base
   def public_action
-    render :nothing => true
+    head :ok
   end
 end
 
@@ -27,6 +27,16 @@ class DefaultUrlOptionsController < ActionController::Base
   end
 end
 
+class OptionalDefaultUrlOptionsController < ActionController::Base
+  def show
+    head :ok
+  end
+
+  def default_url_options
+    { format: 'atom', id: 'default-id' }
+  end
+end
+
 class UrlOptionsController < ActionController::Base
   def from_view
     render :inline => "<%= #{params[:route]} %>"
@@ -43,7 +53,7 @@ end
 
 class ActionMissingController < ActionController::Base
   def action_missing(action)
-    render :text => "Response for #{action}"
+    render plain: "Response for #{action}"
   end
 end
 
@@ -83,6 +93,8 @@ end
 class ControllerInstanceTests < ActiveSupport::TestCase
   def setup
     @empty = EmptyController.new
+    @empty.set_request!(ActionDispatch::Request.new({}))
+    @empty.set_response!(EmptyController.make_response!(@empty.request))
     @contained = Submodule::ContainedEmptyController.new
     @empty_controllers = [@empty, @contained]
   end
@@ -117,8 +129,6 @@ class PerformActionTest < ActionController::TestCase
     # a more accurate simulation of what happens in "real life".
     @controller.logger = ActiveSupport::Logger.new(nil)
 
-    @request     = ActionController::TestRequest.new
-    @response    = ActionController::TestResponse.new
     @request.host = "www.nextangle.com"
   end
 
@@ -168,7 +178,7 @@ class UrlOptionsTest < ActionController::TestCase
         get ':controller/:action'
       end
 
-      get :from_view, :route => "from_view_url"
+      get :from_view, params: { route: "from_view_url" }
 
       assert_equal 'http://www.override.com/from_view', @response.body
       assert_equal 'http://www.override.com/from_view', @controller.send(:from_view_url)
@@ -202,7 +212,7 @@ class DefaultUrlOptionsTest < ActionController::TestCase
         get ':controller/:action'
       end
 
-      get :from_view, :route => "from_view_url"
+      get :from_view, params: { route: "from_view_url" }
 
       assert_equal 'http://www.override.com/from_view?locale=en', @response.body
       assert_equal 'http://www.override.com/from_view?locale=en', @controller.send(:from_view_url)
@@ -219,7 +229,7 @@ class DefaultUrlOptionsTest < ActionController::TestCase
         get ':controller/:action'
       end
 
-      get :from_view, :route => "description_path(1)"
+      get :from_view, params: { route: "description_path(1)" }
 
       assert_equal '/en/descriptions/1', @response.body
       assert_equal '/en/descriptions', @controller.send(:descriptions_path)
@@ -234,7 +244,18 @@ class DefaultUrlOptionsTest < ActionController::TestCase
       assert_equal '/en/descriptions/1.xml', @controller.send(:description_path, 1, :format => "xml")
     end
   end
+end
 
+class OptionalDefaultUrlOptionsControllerTest < ActionController::TestCase
+  def test_default_url_options_override_missing_positional_arguments
+    with_routing do |set|
+      set.draw do
+        get "/things/:id(.:format)" => 'things#show', :as => :thing
+      end
+      assert_equal '/things/1.atom', thing_path('1')
+      assert_equal '/things/default-id.atom', thing_path
+    end
+  end
 end
 
 class EmptyUrlOptionsTest < ActionController::TestCase
diff --git a/actionpack/test/controller/caching_test.rb b/actionpack/test/controller/caching_test.rb
index c0e6a2ebd1..bc0ffd3eaa 100644
--- a/actionpack/test/controller/caching_test.rb
+++ b/actionpack/test/controller/caching_test.rb
@@ -1,5 +1,6 @@
 require 'fileutils'
 require 'abstract_unit'
+require 'lib/controller/fake_models'
 
 CACHE_DIR = 'test_cache'
 # Don't change '/../temp/' cavalierly or you might hose something you don't want hosed
@@ -21,8 +22,6 @@ class FragmentCachingMetalTest < ActionController::TestCase
     @controller.perform_caching = true
     @controller.cache_store = @store
     @params = { controller: 'posts', action: 'index' }
-    @request = ActionController::TestRequest.new
-    @response = ActionController::TestResponse.new
     @controller.params = @params
     @controller.request = @request
     @controller.response = @response
@@ -51,8 +50,6 @@ class FragmentCachingTest < ActionController::TestCase
     @controller.perform_caching = true
     @controller.cache_store = @store
     @params = {:controller => 'posts', :action => 'index'}
-    @request = ActionController::TestRequest.new
-    @response = ActionController::TestResponse.new
     @controller.params = @params
     @controller.request = @request
     @controller.response = @response
@@ -165,6 +162,8 @@ class FunctionalCachingController < CachingController
   end
 
   def formatted_fragment_cached_with_variant
+    request.variant = :phone if params[:v] == "phone"
+
     respond_to do |format|
       format.html.phone
       format.html
@@ -182,8 +181,6 @@ class FunctionalFragmentCachingTest < ActionController::TestCase
     @controller = FunctionalCachingController.new
     @controller.perform_caching = true
     @controller.cache_store = @store
-    @request = ActionController::TestRequest.new
-    @response = ActionController::TestResponse.new
   end
 
   def test_fragment_caching
@@ -210,7 +207,7 @@ CACHED
   end
 
   def test_skipping_fragment_cache_digesting
-    get :fragment_cached_without_digest, :format => "html"
+    get :fragment_cached_without_digest, format: "html"
     assert_response :success
     expected_body = "<body>\n<p>ERB</p>\n</body>\n"
 
@@ -244,7 +241,7 @@ CACHED
   end
 
   def test_html_formatted_fragment_caching
-    get :formatted_fragment_cached, :format => "html"
+    get :formatted_fragment_cached, format: "html"
     assert_response :success
     expected_body = "<body>\n<p>ERB</p>\n</body>\n"
 
@@ -255,7 +252,7 @@ CACHED
   end
 
   def test_xml_formatted_fragment_caching
-    get :formatted_fragment_cached, :format => "xml"
+    get :formatted_fragment_cached, format: "xml"
     assert_response :success
     expected_body = "<body>\n  <p>Builder</p>\n</body>\n"
 
@@ -267,9 +264,7 @@ CACHED
 
 
   def test_fragment_caching_with_variant
-    @request.variant = :phone
-
-    get :formatted_fragment_cached_with_variant, :format => "html"
+    get :formatted_fragment_cached_with_variant, format: "html", params: { v: :phone }
     assert_response :success
     expected_body = "<body>\n<p>PHONE</p>\n</body>\n"
 
@@ -304,30 +299,42 @@ class CacheHelperOutputBufferTest < ActionController::TestCase
   def test_output_buffer
     output_buffer = ActionView::OutputBuffer.new
     controller = MockController.new
-    cache_helper = Object.new
+    cache_helper = Class.new do
+      def self.controller; end;
+      def self.output_buffer; end;
+      def self.output_buffer=; end;
+    end
     cache_helper.extend(ActionView::Helpers::CacheHelper)
-    cache_helper.expects(:controller).returns(controller).at_least(0)
-    cache_helper.expects(:output_buffer).returns(output_buffer).at_least(0)
-    # if the output_buffer is changed, the new one should be html_safe and of the same type
-    cache_helper.expects(:output_buffer=).with(responds_with(:html_safe?, true)).with(instance_of(output_buffer.class)).at_least(0)
 
-    assert_nothing_raised do
-      cache_helper.send :fragment_for, 'Test fragment name', 'Test fragment', &Proc.new{ nil }
+    cache_helper.stub :controller, controller do
+      cache_helper.stub :output_buffer, output_buffer do
+        assert_called_with cache_helper, :output_buffer=, [output_buffer.class.new(output_buffer)] do
+          assert_nothing_raised do
+            cache_helper.send :fragment_for, 'Test fragment name', 'Test fragment', &Proc.new{ nil }
+          end
+        end
+      end
     end
   end
 
   def test_safe_buffer
     output_buffer = ActiveSupport::SafeBuffer.new
     controller = MockController.new
-    cache_helper = Object.new
+    cache_helper = Class.new do
+      def self.controller; end;
+      def self.output_buffer; end;
+      def self.output_buffer=; end;
+    end
     cache_helper.extend(ActionView::Helpers::CacheHelper)
-    cache_helper.expects(:controller).returns(controller).at_least(0)
-    cache_helper.expects(:output_buffer).returns(output_buffer).at_least(0)
-    # if the output_buffer is changed, the new one should be html_safe and of the same type
-    cache_helper.expects(:output_buffer=).with(responds_with(:html_safe?, true)).with(instance_of(output_buffer.class)).at_least(0)
 
-    assert_nothing_raised do
-      cache_helper.send :fragment_for, 'Test fragment name', 'Test fragment', &Proc.new{ nil }
+    cache_helper.stub :controller, controller do
+      cache_helper.stub :output_buffer, output_buffer do
+        assert_called_with cache_helper, :output_buffer=, [output_buffer.class.new(output_buffer)] do
+          assert_nothing_raised do
+            cache_helper.send :fragment_for, 'Test fragment name', 'Test fragment', &Proc.new{ nil }
+          end
+        end
+      end
     end
   end
 end
@@ -349,3 +356,66 @@ class ViewCacheDependencyTest < ActionController::TestCase
     assert_equal %w(trombone flute), HasDependenciesController.new.view_cache_dependencies
   end
 end
+
+class CollectionCacheController < ActionController::Base
+  attr_accessor :partial_rendered_times
+
+  def index
+    @customers = [Customer.new('david', params[:id] || 1)]
+  end
+
+  def index_ordered
+    @customers = [Customer.new('david', 1), Customer.new('david', 2), Customer.new('david', 3)]
+    render 'index'
+  end
+
+  def index_explicit_render
+    @customers = [Customer.new('david', 1)]
+    render partial: 'customers/customer', collection: @customers
+  end
+
+  def index_with_comment
+    @customers = [Customer.new('david', 1)]
+    render partial: 'customers/commented_customer', collection: @customers, as: :customer
+  end
+end
+
+class AutomaticCollectionCacheTest < ActionController::TestCase
+  def setup
+    super
+    @controller = CollectionCacheController.new
+    @controller.perform_caching = true
+    @controller.partial_rendered_times = 0
+    @controller.cache_store = ActiveSupport::Cache::MemoryStore.new
+    ActionView::PartialRenderer.collection_cache = @controller.cache_store
+  end
+
+  def test_collection_fetches_cached_views
+    get :index
+    assert_equal 1, @controller.partial_rendered_times
+
+    get :index
+    assert_equal 1, @controller.partial_rendered_times
+  end
+
+  def test_preserves_order_when_reading_from_cache_plus_rendering
+    get :index, params: { id: 2 }
+    get :index_ordered
+
+    assert_select ':root', "david, 1\n  david, 2\n  david, 3"
+  end
+
+  def test_explicit_render_call_with_options
+    get :index_explicit_render
+
+    assert_select ':root', "david, 1"
+  end
+
+  def test_caching_works_with_beginning_comment
+    get :index_with_comment
+    assert_equal 1, @controller.partial_rendered_times
+
+    get :index_with_comment
+    assert_equal 1, @controller.partial_rendered_times
+  end
+end
diff --git a/actionpack/test/controller/content_type_test.rb b/actionpack/test/controller/content_type_test.rb
index 89667df3a4..c02607b55e 100644
--- a/actionpack/test/controller/content_type_test.rb
+++ b/actionpack/test/controller/content_type_test.rb
@@ -3,30 +3,30 @@ require 'abstract_unit'
 class OldContentTypeController < ActionController::Base
   # :ported:
   def render_content_type_from_body
-    response.content_type = Mime::RSS
-    render :text => "hello world!"
+    response.content_type = Mime[:rss]
+    render body: "hello world!"
   end
 
   # :ported:
   def render_defaults
-    render :text => "hello world!"
+    render body: "hello world!"
   end
 
   # :ported:
   def render_content_type_from_render
-    render :text => "hello world!", :content_type => Mime::RSS
+    render body: "hello world!", :content_type => Mime[:rss]
   end
 
   # :ported:
   def render_charset_from_body
     response.charset = "utf-16"
-    render :text => "hello world!"
+    render body: "hello world!"
   end
 
   # :ported:
   def render_nil_charset_from_body
     response.charset = nil
-    render :text => "hello world!"
+    render body: "hello world!"
   end
 
   def render_default_for_erb
@@ -36,16 +36,16 @@ class OldContentTypeController < ActionController::Base
   end
 
   def render_change_for_builder
-    response.content_type = Mime::HTML
+    response.content_type = Mime[:html]
     render :action => "render_default_for_builder"
   end
 
   def render_default_content_types_for_respond_to
     respond_to do |format|
-      format.html { render :text   => "hello world!" }
-      format.xml  { render :action => "render_default_content_types_for_respond_to" }
-      format.js   { render :text   => "hello world!" }
-      format.rss  { render :text   => "hello world!", :content_type => Mime::XML }
+      format.html { render body: "hello world!" }
+      format.xml  { render action: "render_default_content_types_for_respond_to" }
+      format.js   { render body: "hello world!" }
+      format.rss  { render body: "hello world!", content_type: Mime[:xml] }
     end
   end
 end
@@ -64,68 +64,68 @@ class ContentTypeTest < ActionController::TestCase
   def test_render_defaults
     get :render_defaults
     assert_equal "utf-8", @response.charset
-    assert_equal Mime::HTML, @response.content_type
+    assert_equal Mime[:text], @response.content_type
   end
 
   def test_render_changed_charset_default
     with_default_charset "utf-16" do
       get :render_defaults
       assert_equal "utf-16", @response.charset
-      assert_equal Mime::HTML, @response.content_type
+      assert_equal Mime[:text], @response.content_type
     end
   end
 
   # :ported:
   def test_content_type_from_body
     get :render_content_type_from_body
-    assert_equal Mime::RSS, @response.content_type
+    assert_equal Mime[:rss], @response.content_type
     assert_equal "utf-8", @response.charset
   end
 
   # :ported:
   def test_content_type_from_render
     get :render_content_type_from_render
-    assert_equal Mime::RSS, @response.content_type
+    assert_equal Mime[:rss], @response.content_type
     assert_equal "utf-8", @response.charset
   end
 
   # :ported:
   def test_charset_from_body
     get :render_charset_from_body
-    assert_equal Mime::HTML, @response.content_type
+    assert_equal Mime[:text], @response.content_type
     assert_equal "utf-16", @response.charset
   end
 
   # :ported:
   def test_nil_charset_from_body
     get :render_nil_charset_from_body
-    assert_equal Mime::HTML, @response.content_type
+    assert_equal Mime[:text], @response.content_type
     assert_equal "utf-8", @response.charset, @response.headers.inspect
   end
 
   def test_nil_default_for_erb
     with_default_charset nil do
       get :render_default_for_erb
-      assert_equal Mime::HTML, @response.content_type
+      assert_equal Mime[:html], @response.content_type
       assert_nil @response.charset, @response.headers.inspect
     end
   end
 
   def test_default_for_erb
     get :render_default_for_erb
-    assert_equal Mime::HTML, @response.content_type
+    assert_equal Mime[:html], @response.content_type
     assert_equal "utf-8", @response.charset
   end
 
   def test_default_for_builder
     get :render_default_for_builder
-    assert_equal Mime::XML, @response.content_type
+    assert_equal Mime[:xml], @response.content_type
     assert_equal "utf-8", @response.charset
   end
 
   def test_change_for_builder
     get :render_change_for_builder
-    assert_equal Mime::HTML, @response.content_type
+    assert_equal Mime[:html], @response.content_type
     assert_equal "utf-8", @response.charset
   end
 
@@ -144,24 +144,24 @@ class AcceptBasedContentTypeTest < ActionController::TestCase
   tests OldContentTypeController
 
   def test_render_default_content_types_for_respond_to
-    @request.accept = Mime::HTML.to_s
+    @request.accept = Mime[:html].to_s
     get :render_default_content_types_for_respond_to
-    assert_equal Mime::HTML, @response.content_type
+    assert_equal Mime[:html], @response.content_type
 
-    @request.accept = Mime::JS.to_s
+    @request.accept = Mime[:js].to_s
     get :render_default_content_types_for_respond_to
-    assert_equal Mime::JS, @response.content_type
+    assert_equal Mime[:js], @response.content_type
   end
 
   def test_render_default_content_types_for_respond_to_with_template
-    @request.accept = Mime::XML.to_s
+    @request.accept = Mime[:xml].to_s
     get :render_default_content_types_for_respond_to
-    assert_equal Mime::XML, @response.content_type
+    assert_equal Mime[:xml], @response.content_type
   end
 
   def test_render_default_content_types_for_respond_to_with_overwrite
-    @request.accept = Mime::RSS.to_s
+    @request.accept = Mime[:rss].to_s
     get :render_default_content_types_for_respond_to
-    assert_equal Mime::XML, @response.content_type
+    assert_equal Mime[:xml], @response.content_type
   end
 end
diff --git a/actionpack/test/controller/default_url_options_with_before_action_test.rb b/actionpack/test/controller/default_url_options_with_before_action_test.rb
index 656fd0431e..12fbe0424e 100644
--- a/actionpack/test/controller/default_url_options_with_before_action_test.rb
+++ b/actionpack/test/controller/default_url_options_with_before_action_test.rb
@@ -1,13 +1,12 @@
 require 'abstract_unit'
 
-
 class ControllerWithBeforeActionAndDefaultUrlOptions < ActionController::Base
 
   before_action { I18n.locale = params[:locale] }
   after_action { I18n.locale = "en" }
 
   def target
-    render :text => "final response"
+    render plain: "final response"
   end
 
   def redirect
@@ -23,7 +22,7 @@ class ControllerWithBeforeActionAndDefaultUrlOptionsTest < ActionController::Tes
 
   # This test has its roots in issue #1872
   test "should redirect with correct locale :de" do
-    get :redirect, :locale => "de"
+    get :redirect, params: { locale: "de" }
     assert_redirected_to "/controller_with_before_action_and_default_url_options/target?locale=de"
   end
 end
diff --git a/actionpack/test/controller/filters_test.rb b/actionpack/test/controller/filters_test.rb
index b9fb6be4e3..08271012e9 100644
--- a/actionpack/test/controller/filters_test.rb
+++ b/actionpack/test/controller/filters_test.rb
@@ -13,20 +13,9 @@ class ActionController::Base
       filters.map!(&:raw_filter)
     end
   end
-
-  def assigns(key = nil)
-    assigns = {}
-    instance_variables.each do |ivar|
-      next if ActionController::Base.protected_instance_variables.include?(ivar)
-      assigns[ivar[1..-1]] = instance_variable_get(ivar)
-    end
-
-    key.nil? ? assigns : assigns[key.to_s]
-  end
 end
 
 class FilterTest < ActionController::TestCase
-
   class TestController < ActionController::Base
     before_action :ensure_login
     after_action  :clean_up
@@ -51,7 +40,7 @@ class FilterTest < ActionController::TestCase
     before_action :ensure_login, :except => [:go_wild]
 
     def go_wild
-      render :text => "gobble"
+      render plain: "gobble"
     end
   end
 
@@ -62,7 +51,7 @@ class FilterTest < ActionController::TestCase
 
     (1..3).each do |i|
       define_method "fail_#{i}" do
-        render :text => i.to_s
+        render plain: i.to_s
       end
     end
 
@@ -233,7 +222,7 @@ class FilterTest < ActionController::TestCase
     skip_before_action :clean_up_tmp, only: :login, if: -> { true }
 
     def login
-      render text: 'ok'
+      render plain: 'ok'
     end
   end
 
@@ -245,7 +234,7 @@ class FilterTest < ActionController::TestCase
     skip_before_action :clean_up_tmp, if: -> { true }, except: :login
 
     def login
-      render text: 'ok'
+      render plain: 'ok'
     end
   end
 
@@ -269,11 +258,11 @@ class FilterTest < ActionController::TestCase
     before_action :ensure_login, :only => :index
 
     def index
-      render :text => 'ok'
+      render plain: 'ok'
     end
 
     def public
-      render :text => 'ok'
+      render plain: 'ok'
     end
   end
 
@@ -283,7 +272,7 @@ class FilterTest < ActionController::TestCase
     before_action :ensure_login
 
     def index
-      render :text => 'ok'
+      render plain: 'ok'
     end
 
     private
@@ -394,7 +383,7 @@ class FilterTest < ActionController::TestCase
     before_action(AuditFilter)
 
     def show
-      render :text => "hello"
+      render plain: "hello"
     end
   end
 
@@ -432,11 +421,11 @@ class FilterTest < ActionController::TestCase
     before_action :second, :only => :foo
 
     def foo
-      render :text => 'foo'
+      render plain: 'foo'
     end
 
     def bar
-      render :text => 'bar'
+      render plain: 'bar'
     end
 
     protected
@@ -453,7 +442,7 @@ class FilterTest < ActionController::TestCase
     before_action :choose
 
     %w(foo bar baz).each do |action|
-      define_method(action) { render :text => action }
+      define_method(action) { render plain: action }
     end
 
     private
@@ -482,7 +471,7 @@ class FilterTest < ActionController::TestCase
       @ran_filter << 'between_before_all_and_after_all'
     end
     def show
-      render :text => 'hello'
+      render plain: 'hello'
     end
   end
 
@@ -492,7 +481,7 @@ class FilterTest < ActionController::TestCase
     def around(controller)
       yield
     rescue ErrorToRescue => ex
-      controller.__send__ :render, :text => "I rescued this: #{ex.inspect}"
+      controller.__send__ :render, plain: "I rescued this: #{ex.inspect}"
     end
   end
 
@@ -561,7 +550,7 @@ class FilterTest < ActionController::TestCase
   def test_after_actions_are_not_run_if_around_action_does_not_yield
     controller = NonYieldingAroundFilterController.new
     test_process(controller, "index")
-    assert_equal ["filter_one", "it didn't yield"], controller.assigns['filters']
+    assert_equal ["filter_one", "it didn't yield"], controller.instance_variable_get(:@filters)
   end
 
   def test_added_action_to_inheritance_graph
@@ -578,140 +567,141 @@ class FilterTest < ActionController::TestCase
 
   def test_running_actions
     test_process(PrependingController)
-    assert_equal %w( wonderful_life ensure_login ), assigns["ran_filter"]
+    assert_equal %w( wonderful_life ensure_login ),
+      @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_running_actions_with_proc
     test_process(ProcController)
-    assert assigns["ran_proc_action"]
+    assert @controller.instance_variable_get(:@ran_proc_action)
   end
 
   def test_running_actions_with_implicit_proc
     test_process(ImplicitProcController)
-    assert assigns["ran_proc_action"]
+    assert @controller.instance_variable_get(:@ran_proc_action)
   end
 
   def test_running_actions_with_class
     test_process(AuditController)
-    assert assigns["was_audited"]
+    assert @controller.instance_variable_get(:@was_audited)
   end
 
   def test_running_anomolous_yet_valid_condition_actions
     test_process(AnomolousYetValidConditionController)
-    assert_equal %w( ensure_login ), assigns["ran_filter"]
-    assert assigns["ran_class_action"]
-    assert assigns["ran_proc_action1"]
-    assert assigns["ran_proc_action2"]
+    assert_equal %w( ensure_login ), @controller.instance_variable_get(:@ran_filter)
+    assert @controller.instance_variable_get(:@ran_class_action)
+    assert @controller.instance_variable_get(:@ran_proc_action1)
+    assert @controller.instance_variable_get(:@ran_proc_action2)
 
     test_process(AnomolousYetValidConditionController, "show_without_action")
-    assert_nil assigns["ran_filter"]
-    assert !assigns["ran_class_action"]
-    assert !assigns["ran_proc_action1"]
-    assert !assigns["ran_proc_action2"]
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
+    assert_not @controller.instance_variable_defined?(:@ran_class_action)
+    assert_not @controller.instance_variable_defined?(:@ran_proc_action1)
+    assert_not @controller.instance_variable_defined?(:@ran_proc_action2)
   end
 
   def test_running_conditional_options
     test_process(ConditionalOptionsFilter)
-    assert_equal %w( ensure_login ), assigns["ran_filter"]
+    assert_equal %w( ensure_login ), @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_running_conditional_skip_options
     test_process(ConditionalOptionsSkipFilter)
-    assert_equal %w( ensure_login ), assigns["ran_filter"]
+    assert_equal %w( ensure_login ), @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_if_is_ignored_when_used_with_only
     test_process(SkipFilterUsingOnlyAndIf, 'login')
-    assert_nil assigns['ran_filter']
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
   end
 
   def test_except_is_ignored_when_used_with_if
     test_process(SkipFilterUsingIfAndExcept, 'login')
-    assert_equal %w(ensure_login), assigns["ran_filter"]
+    assert_equal %w(ensure_login), @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_skipping_class_actions
     test_process(ClassController)
-    assert_equal true, assigns["ran_class_action"]
+    assert_equal true, @controller.instance_variable_get(:@ran_class_action)
 
     skipping_class_controller = Class.new(ClassController) do
       skip_before_action ConditionalClassFilter
     end
 
     test_process(skipping_class_controller)
-    assert_nil assigns['ran_class_action']
+    assert_not @controller.instance_variable_defined?(:@ran_class_action)
   end
 
   def test_running_collection_condition_actions
     test_process(ConditionalCollectionFilterController)
-    assert_equal %w( ensure_login ), assigns["ran_filter"]
+    assert_equal %w( ensure_login ), @controller.instance_variable_get(:@ran_filter)
     test_process(ConditionalCollectionFilterController, "show_without_action")
-    assert_nil assigns["ran_filter"]
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
     test_process(ConditionalCollectionFilterController, "another_action")
-    assert_nil assigns["ran_filter"]
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
   end
 
   def test_running_only_condition_actions
     test_process(OnlyConditionSymController)
-    assert_equal %w( ensure_login ), assigns["ran_filter"]
+    assert_equal %w( ensure_login ), @controller.instance_variable_get(:@ran_filter)
     test_process(OnlyConditionSymController, "show_without_action")
-    assert_nil assigns["ran_filter"]
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
 
     test_process(OnlyConditionProcController)
-    assert assigns["ran_proc_action"]
+    assert @controller.instance_variable_get(:@ran_proc_action)
     test_process(OnlyConditionProcController, "show_without_action")
-    assert !assigns["ran_proc_action"]
+    assert_not @controller.instance_variable_defined?(:@ran_proc_action)
 
     test_process(OnlyConditionClassController)
-    assert assigns["ran_class_action"]
+    assert @controller.instance_variable_get(:@ran_class_action)
     test_process(OnlyConditionClassController, "show_without_action")
-    assert !assigns["ran_class_action"]
+    assert_not @controller.instance_variable_defined?(:@ran_class_action)
   end
 
   def test_running_except_condition_actions
     test_process(ExceptConditionSymController)
-    assert_equal %w( ensure_login ), assigns["ran_filter"]
+    assert_equal %w( ensure_login ), @controller.instance_variable_get(:@ran_filter)
     test_process(ExceptConditionSymController, "show_without_action")
-    assert_nil assigns["ran_filter"]
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
 
     test_process(ExceptConditionProcController)
-    assert assigns["ran_proc_action"]
+    assert @controller.instance_variable_get(:@ran_proc_action)
     test_process(ExceptConditionProcController, "show_without_action")
-    assert !assigns["ran_proc_action"]
+    assert_not @controller.instance_variable_defined?(:@ran_proc_action)
 
     test_process(ExceptConditionClassController)
-    assert assigns["ran_class_action"]
+    assert @controller.instance_variable_get(:@ran_class_action)
     test_process(ExceptConditionClassController, "show_without_action")
-    assert !assigns["ran_class_action"]
+    assert_not @controller.instance_variable_defined?(:@ran_class_action)
   end
 
   def test_running_only_condition_and_conditional_options
     test_process(OnlyConditionalOptionsFilter, "show")
-    assert_not assigns["ran_conditional_index_proc"]
+    assert_not @controller.instance_variable_defined?(:@ran_conditional_index_proc)
   end
 
   def test_running_before_and_after_condition_actions
     test_process(BeforeAndAfterConditionController)
-    assert_equal %w( ensure_login clean_up_tmp), assigns["ran_filter"]
+    assert_equal %w( ensure_login clean_up_tmp), @controller.instance_variable_get(:@ran_filter)
     test_process(BeforeAndAfterConditionController, "show_without_action")
-    assert_nil assigns["ran_filter"]
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
   end
 
   def test_around_action
     test_process(AroundFilterController)
-    assert assigns["before_ran"]
-    assert assigns["after_ran"]
+    assert @controller.instance_variable_get(:@before_ran)
+    assert @controller.instance_variable_get(:@after_ran)
   end
 
   def test_before_after_class_action
     test_process(BeforeAfterClassFilterController)
-    assert assigns["before_ran"]
-    assert assigns["after_ran"]
+    assert @controller.instance_variable_get(:@before_ran)
+    assert @controller.instance_variable_get(:@after_ran)
   end
 
   def test_having_properties_in_around_action
     test_process(AroundFilterController)
-    assert_equal "before and after", assigns["execution_log"]
+    assert_equal "before and after", @controller.instance_variable_get(:@execution_log)
   end
 
   def test_prepending_and_appending_around_action
@@ -724,33 +714,33 @@ class FilterTest < ActionController::TestCase
   def test_rendering_breaks_actioning_chain
     response = test_process(RenderingController)
     assert_equal "something else", response.body
-    assert !assigns["ran_action"]
+    assert_not @controller.instance_variable_defined?(:@ran_action)
   end
 
   def test_before_action_rendering_breaks_actioning_chain_for_after_action
     test_process(RenderingController)
-    assert_equal %w( before_action_rendering ), assigns["ran_filter"]
-    assert !assigns["ran_action"]
+    assert_equal %w( before_action_rendering ), @controller.instance_variable_get(:@ran_filter)
+    assert_not @controller.instance_variable_defined?(:@ran_action)
   end
 
   def test_before_action_redirects_breaks_actioning_chain_for_after_action
     test_process(BeforeActionRedirectionController)
     assert_response :redirect
     assert_equal "http://test.host/filter_test/before_action_redirection/target_of_redirection", redirect_to_url
-    assert_equal %w( before_action_redirects ), assigns["ran_filter"]
+    assert_equal %w( before_action_redirects ), @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_before_action_rendering_breaks_actioning_chain_for_preprend_after_action
     test_process(RenderingForPrependAfterActionController)
-    assert_equal %w( before_action_rendering ), assigns["ran_filter"]
-    assert !assigns["ran_action"]
+    assert_equal %w( before_action_rendering ), @controller.instance_variable_get(:@ran_filter)
+    assert_not @controller.instance_variable_defined?(:@ran_action)
   end
 
   def test_before_action_redirects_breaks_actioning_chain_for_preprend_after_action
     test_process(BeforeActionRedirectionForPrependAfterActionController)
     assert_response :redirect
     assert_equal "http://test.host/filter_test/before_action_redirection_for_prepend_after_action/target_of_redirection", redirect_to_url
-    assert_equal %w( before_action_redirects ), assigns["ran_filter"]
+    assert_equal %w( before_action_redirects ), @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_actions_with_mixed_specialization_run_in_order
@@ -767,35 +757,34 @@ class FilterTest < ActionController::TestCase
 
   def test_dynamic_dispatch
     %w(foo bar baz).each do |action|
-      request = ActionController::TestRequest.new
-      request.query_parameters[:choose] = action
-      response = DynamicDispatchController.action(action).call(request.env).last
+      @request.query_parameters[:choose] = action
+      response = DynamicDispatchController.action(action).call(@request.env).last
       assert_equal action, response.body
     end
   end
 
   def test_running_prepended_before_and_after_action
     test_process(PrependingBeforeAndAfterController)
-    assert_equal %w( before_all between_before_all_and_after_all after_all ), assigns["ran_filter"]
+    assert_equal %w( before_all between_before_all_and_after_all after_all ), @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_skipping_and_limiting_controller
     test_process(SkippingAndLimitedController, "index")
-    assert_equal %w( ensure_login ), assigns["ran_filter"]
+    assert_equal %w( ensure_login ), @controller.instance_variable_get(:@ran_filter)
     test_process(SkippingAndLimitedController, "public")
-    assert_nil assigns["ran_filter"]
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
   end
 
   def test_skipping_and_reordering_controller
     test_process(SkippingAndReorderingController, "index")
-    assert_equal %w( find_record ensure_login ), assigns["ran_filter"]
+    assert_equal %w( find_record ensure_login ), @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_conditional_skipping_of_actions
     test_process(ConditionalSkippingController, "login")
-    assert_nil assigns["ran_filter"]
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
     test_process(ConditionalSkippingController, "change_password")
-    assert_equal %w( ensure_login find_user ), assigns["ran_filter"]
+    assert_equal %w( ensure_login find_user ), @controller.instance_variable_get(:@ran_filter)
 
     test_process(ConditionalSkippingController, "login")
     assert !@controller.instance_variable_defined?("@ran_after_action")
@@ -805,23 +794,23 @@ class FilterTest < ActionController::TestCase
 
   def test_conditional_skipping_of_actions_when_parent_action_is_also_conditional
     test_process(ChildOfConditionalParentController)
-    assert_equal %w( conditional_in_parent_before conditional_in_parent_after ), assigns['ran_filter']
+    assert_equal %w( conditional_in_parent_before conditional_in_parent_after ), @controller.instance_variable_get(:@ran_filter)
     test_process(ChildOfConditionalParentController, 'another_action')
-    assert_nil assigns['ran_filter']
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
   end
 
   def test_condition_skipping_of_actions_when_siblings_also_have_conditions
     test_process(ChildOfConditionalParentController)
-    assert_equal %w( conditional_in_parent_before conditional_in_parent_after ), assigns['ran_filter']
+    assert_equal %w( conditional_in_parent_before conditional_in_parent_after ), @controller.instance_variable_get(:@ran_filter)
     test_process(AnotherChildOfConditionalParentController)
-    assert_equal %w( conditional_in_parent_after ), assigns['ran_filter']
+    assert_equal %w( conditional_in_parent_after ), @controller.instance_variable_get(:@ran_filter)
     test_process(ChildOfConditionalParentController)
-    assert_equal %w( conditional_in_parent_before conditional_in_parent_after ), assigns['ran_filter']
+    assert_equal %w( conditional_in_parent_before conditional_in_parent_after ), @controller.instance_variable_get(:@ran_filter)
   end
 
   def test_changing_the_requirements
     test_process(ChangingTheRequirementsController, "go_wild")
-    assert_nil assigns['ran_filter']
+    assert_not @controller.instance_variable_defined?(:@ran_filter)
   end
 
   def test_a_rescuing_around_action
@@ -830,27 +819,25 @@ class FilterTest < ActionController::TestCase
       response = test_process(RescuedController)
     end
 
-    assert response.success?
+    assert response.successful?
     assert_equal("I rescued this: #<FilterTest::ErrorToRescue: Something made the bad noise.>", response.body)
   end
 
   def test_actions_obey_only_and_except_for_implicit_actions
     test_process(ImplicitActionsController, 'show')
-    assert_equal 'Except', assigns(:except)
-    assert_nil assigns(:only)
+    assert_equal 'Except', @controller.instance_variable_get(:@except)
+    assert_not @controller.instance_variable_defined?(:@only)
     assert_equal 'show', response.body
 
     test_process(ImplicitActionsController, 'edit')
-    assert_equal 'Only', assigns(:only)
-    assert_nil assigns(:except)
+    assert_equal 'Only', @controller.instance_variable_get(:@only)
+    assert_not @controller.instance_variable_defined?(:@except)
     assert_equal 'edit', response.body
   end
 
   private
     def test_process(controller, action = "show")
       @controller = controller.is_a?(Class) ? controller.new : controller
-      @request    = ActionController::TestRequest.new
-      @response   = ActionController::TestResponse.new
 
       process(action)
     end
@@ -967,8 +954,15 @@ class ControllerWithAllTypesOfFilters < PostsController
 end
 
 class ControllerWithTwoLessFilters < ControllerWithAllTypesOfFilters
-  skip_action_callback :around_again
-  skip_action_callback :after
+  skip_around_action :around_again
+  skip_after_action :after
+end
+
+class SkipFilterUsingSkipActionCallback < ControllerWithAllTypesOfFilters
+  ActiveSupport::Deprecation.silence do
+    skip_action_callback :around_again
+    skip_action_callback :after
+  end
 end
 
 class YieldingAroundFiltersTest < ActionController::TestCase
@@ -1004,8 +998,8 @@ class YieldingAroundFiltersTest < ActionController::TestCase
 
   def test_with_proc
     test_process(ControllerWithProcFilter,'no_raise')
-    assert assigns['before']
-    assert assigns['after']
+    assert @controller.instance_variable_get(:@before)
+    assert @controller.instance_variable_get(:@after)
   end
 
   def test_nested_actions
@@ -1026,12 +1020,12 @@ class YieldingAroundFiltersTest < ActionController::TestCase
 
   def test_action_order_with_all_action_types
     test_process(ControllerWithAllTypesOfFilters,'no_raise')
-    assert_equal 'before around (before yield) around_again (before yield) around_again (after yield) after around (after yield)', assigns['ran_filter'].join(' ')
+    assert_equal 'before around (before yield) around_again (before yield) around_again (after yield) after around (after yield)', @controller.instance_variable_get(:@ran_filter).join(' ')
   end
 
   def test_action_order_with_skip_action_method
     test_process(ControllerWithTwoLessFilters,'no_raise')
-    assert_equal 'before around (before yield) around (after yield)', assigns['ran_filter'].join(' ')
+    assert_equal 'before around (before yield) around (after yield)', @controller.instance_variable_get(:@ran_filter).join(' ')
   end
 
   def test_first_action_in_multiple_before_action_chain_halts
@@ -1055,6 +1049,27 @@ class YieldingAroundFiltersTest < ActionController::TestCase
     assert_equal 3, controller.instance_variable_get(:@try)
   end
 
+  def test_skipping_with_skip_action_callback
+    test_process(SkipFilterUsingSkipActionCallback,'no_raise')
+    assert_equal 'before around (before yield) around (after yield)', @controller.instance_variable_get(:@ran_filter).join(' ')
+  end
+
+  def test_deprecated_skip_action_callback
+    assert_deprecated do
+      Class.new(PostsController) do
+        skip_action_callback :clean_up
+      end
+    end
+  end
+
+  def test_deprecated_skip_filter
+    assert_deprecated do
+      Class.new(PostsController) do
+        skip_filter :clean_up
+      end
+    end
+  end
+
   protected
     def test_process(controller, action = "show")
       @controller = controller.is_a?(Class) ? controller.new : controller
diff --git a/actionpack/test/controller/flash_hash_test.rb b/actionpack/test/controller/flash_hash_test.rb
index d979b561f2..081288ef21 100644
--- a/actionpack/test/controller/flash_hash_test.rb
+++ b/actionpack/test/controller/flash_hash_test.rb
@@ -57,33 +57,36 @@ module ActionDispatch
 
     def test_to_session_value
       @hash['foo'] = 'bar'
-      assert_equal({'flashes' => {'foo' => 'bar'}, 'discard' => []}, @hash.to_session_value)
-
-      @hash.discard('foo')
-      assert_equal({'flashes' => {'foo' => 'bar'}, 'discard' => %w[foo]}, @hash.to_session_value)
+      assert_equal({'flashes' => {'foo' => 'bar'}}, @hash.to_session_value)
 
       @hash.now['qux'] = 1
-      assert_equal({'flashes' => {'foo' => 'bar', 'qux' => 1}, 'discard' => %w[foo qux]}, @hash.to_session_value)
+      assert_equal({'flashes' => {'foo' => 'bar'}}, @hash.to_session_value)
+
+      @hash.discard('foo')
+      assert_equal(nil, @hash.to_session_value)
 
       @hash.sweep
       assert_equal(nil, @hash.to_session_value)
     end
 
     def test_from_session_value
-      rails_3_2_cookie = 'BAh7B0kiD3Nlc3Npb25faWQGOgZFRkkiJWY4ZTFiODE1MmJhNzYwOWMyOGJiYjE3ZWM5MjYzYmE3BjsAVEkiCmZsYXNoBjsARm86JUFjdGlvbkRpc3BhdGNoOjpGbGFzaDo6Rmxhc2hIYXNoCToKQHVzZWRvOghTZXQGOgpAaGFzaHsAOgxAY2xvc2VkRjoNQGZsYXNoZXN7BkkiDG1lc3NhZ2UGOwBGSSIKSGVsbG8GOwBGOglAbm93MA=='
+      # {"session_id"=>"f8e1b8152ba7609c28bbb17ec9263ba7", "flash"=>#<ActionDispatch::Flash::FlashHash:0x00000000000000 @used=#<Set: {"farewell"}>, @closed=false, @flashes={"greeting"=>"Hello", "farewell"=>"Goodbye"}, @now=nil>}
+      rails_3_2_cookie = 'BAh7B0kiD3Nlc3Npb25faWQGOgZFRkkiJWY4ZTFiODE1MmJhNzYwOWMyOGJiYjE3ZWM5MjYzYmE3BjsAVEkiCmZsYXNoBjsARm86JUFjdGlvbkRpc3BhdGNoOjpGbGFzaDo6Rmxhc2hIYXNoCToKQHVzZWRvOghTZXQGOgpAaGFzaHsGSSINZmFyZXdlbGwGOwBUVDoMQGNsb3NlZEY6DUBmbGFzaGVzewdJIg1ncmVldGluZwY7AFRJIgpIZWxsbwY7AFRJIg1mYXJld2VsbAY7AFRJIgxHb29kYnllBjsAVDoJQG5vdzA='
       session = Marshal.load(Base64.decode64(rails_3_2_cookie))
       hash = Flash::FlashHash.from_session_value(session['flash'])
-      assert_equal({'flashes' => {'message' => 'Hello'}, 'discard' => %w[message]}, hash.to_session_value)
+      assert_equal({'greeting' => 'Hello'}, hash.to_hash)
+      assert_equal(nil, hash.to_session_value)
     end
 
     def test_from_session_value_on_json_serializer
-      decrypted_data = "{ \"session_id\":\"d98bdf6d129618fc2548c354c161cfb5\", \"flash\":{\"discard\":[], \"flashes\":{\"message\":\"hey you\"}} }"
+      decrypted_data = "{ \"session_id\":\"d98bdf6d129618fc2548c354c161cfb5\", \"flash\":{\"discard\":[\"farewell\"], \"flashes\":{\"greeting\":\"Hello\",\"farewell\":\"Goodbye\"}} }"
       session = ActionDispatch::Cookies::JsonSerializer.load(decrypted_data)
       hash = Flash::FlashHash.from_session_value(session['flash'])
 
-      assert_equal({'discard' => %w[message], 'flashes' => { 'message' => 'hey you'}}, hash.to_session_value)
-      assert_equal "hey you", hash[:message]
-      assert_equal "hey you", hash["message"]
+      assert_equal({'greeting' => 'Hello'}, hash.to_hash)
+      assert_equal(nil, hash.to_session_value)
+      assert_equal "Hello", hash[:greeting]
+      assert_equal "Hello", hash["greeting"]
     end
 
     def test_empty?
diff --git a/actionpack/test/controller/flash_test.rb b/actionpack/test/controller/flash_test.rb
index 3720a920d0..b063d769a4 100644
--- a/actionpack/test/controller/flash_test.rb
+++ b/actionpack/test/controller/flash_test.rb
@@ -57,7 +57,7 @@ class FlashTest < ActionController::TestCase
 
     def std_action
       @flash_copy = {}.update(flash)
-      render :nothing => true
+      head :ok
     end
 
     def filter_halting_action
@@ -103,54 +103,55 @@ class FlashTest < ActionController::TestCase
     get :set_flash
 
     get :use_flash
-    assert_equal "hello", assigns["flash_copy"]["that"]
-    assert_equal "hello", assigns["flashy"]
+    assert_equal "hello", @controller.instance_variable_get(:@flash_copy)["that"]
+    assert_equal "hello", @controller.instance_variable_get(:@flashy)
 
     get :use_flash
-    assert_nil assigns["flash_copy"]["that"], "On second flash"
+    assert_nil @controller.instance_variable_get(:@flash_copy)["that"], "On second flash"
   end
 
   def test_keep_flash
     get :set_flash
 
     get :use_flash_and_keep_it
-    assert_equal "hello", assigns["flash_copy"]["that"]
-    assert_equal "hello", assigns["flashy"]
+    assert_equal "hello", @controller.instance_variable_get(:@flash_copy)["that"]
+    assert_equal "hello", @controller.instance_variable_get(:@flashy)
 
     get :use_flash
-    assert_equal "hello", assigns["flash_copy"]["that"], "On second flash"
+    assert_equal "hello", @controller.instance_variable_get(:@flash_copy)["that"], "On second flash"
 
     get :use_flash
-    assert_nil assigns["flash_copy"]["that"], "On third flash"
+    assert_nil @controller.instance_variable_get(:@flash_copy)["that"], "On third flash"
   end
 
   def test_flash_now
     get :set_flash_now
-    assert_equal "hello", assigns["flash_copy"]["that"]
-    assert_equal "bar"  , assigns["flash_copy"]["foo"]
-    assert_equal "hello", assigns["flashy"]
+    assert_equal "hello", @controller.instance_variable_get(:@flash_copy)["that"]
+    assert_equal "bar", @controller.instance_variable_get(:@flash_copy)["foo"]
+    assert_equal "hello", @controller.instance_variable_get(:@flashy)
 
     get :attempt_to_use_flash_now
-    assert_nil assigns["flash_copy"]["that"]
-    assert_nil assigns["flash_copy"]["foo"]
-    assert_nil assigns["flashy"]
+    assert_nil @controller.instance_variable_get(:@flash_copy)["that"]
+    assert_nil @controller.instance_variable_get(:@flash_copy)["foo"]
+    assert_nil @controller.instance_variable_get(:@flashy)
   end
 
   def test_update_flash
     get :set_flash
     get :use_flash_and_update_it
-    assert_equal "hello",       assigns["flash_copy"]["that"]
-    assert_equal "hello again", assigns["flash_copy"]["this"]
+    assert_equal "hello", @controller.instance_variable_get(:@flash_copy)["that"]
+    assert_equal "hello again", @controller.instance_variable_get(:@flash_copy)["this"]
     get :use_flash
-    assert_nil                  assigns["flash_copy"]["that"], "On second flash"
-    assert_equal "hello again", assigns["flash_copy"]["this"], "On second flash"
+    assert_nil @controller.instance_variable_get(:@flash_copy)["that"], "On second flash"
+    assert_equal "hello again",
+      @controller.instance_variable_get(:@flash_copy)["this"], "On second flash"
   end
 
   def test_flash_after_reset_session
     get :use_flash_after_reset_session
-    assert_equal "hello",    assigns["flashy_that"]
-    assert_equal "good-bye", assigns["flashy_this"]
-    assert_nil   assigns["flashy_that_reset"]
+    assert_equal "hello", @controller.instance_variable_get(:@flashy_that)
+    assert_equal "good-bye", @controller.instance_variable_get(:@flashy_this)
+    assert_nil @controller.instance_variable_get(:@flashy_that_reset)
   end
 
   def test_does_not_set_the_session_if_the_flash_is_empty
@@ -160,13 +161,13 @@ class FlashTest < ActionController::TestCase
 
   def test_sweep_after_halted_action_chain
     get :std_action
-    assert_nil assigns["flash_copy"]["foo"]
+    assert_nil @controller.instance_variable_get(:@flash_copy)["foo"]
     get :filter_halting_action
-    assert_equal "bar", assigns["flash_copy"]["foo"]
+    assert_equal "bar", @controller.instance_variable_get(:@flash_copy)["foo"]
     get :std_action # follow redirection
-    assert_equal "bar", assigns["flash_copy"]["foo"]
+    assert_equal "bar", @controller.instance_variable_get(:@flash_copy)["foo"]
     get :std_action
-    assert_nil assigns["flash_copy"]["foo"]
+    assert_nil @controller.instance_variable_get(:@flash_copy)["foo"]
   end
 
   def test_keep_and_discard_return_values
@@ -288,16 +289,16 @@ class FlashIntegrationTest < ActionDispatch::IntegrationTest
   def test_setting_flash_does_not_raise_in_following_requests
     with_test_route_set do
       env = { 'action_dispatch.request.flash_hash' => ActionDispatch::Flash::FlashHash.new }
-      get '/set_flash', nil, env
-      get '/set_flash', nil, env
+      get '/set_flash', env: env
+      get '/set_flash', env: env
     end
   end
 
   def test_setting_flash_now_does_not_raise_in_following_requests
     with_test_route_set do
       env = { 'action_dispatch.request.flash_hash' => ActionDispatch::Flash::FlashHash.new }
-      get '/set_flash_now', nil, env
-      get '/set_flash_now', nil, env
+      get '/set_flash_now', env: env
+      get '/set_flash_now', env: env
     end
   end
 
@@ -312,9 +313,11 @@ class FlashIntegrationTest < ActionDispatch::IntegrationTest
   private
 
     # Overwrite get to send SessionSecret in env hash
-    def get(path, parameters = nil, env = {})
-      env["action_dispatch.key_generator"] ||= Generator
-      super
+    def get(path, *args)
+      args[0] ||= {}
+      args[0][:env] ||= {}
+      args[0][:env]["action_dispatch.key_generator"] ||= Generator
+      super(path, *args)
     end
 
     def with_test_route_set
@@ -326,7 +329,7 @@ class FlashIntegrationTest < ActionDispatch::IntegrationTest
         @app = self.class.build_app(set) do |middleware|
           middleware.use ActionDispatch::Session::CookieStore, :key => SessionKey
           middleware.use ActionDispatch::Flash
-          middleware.delete "ActionDispatch::ShowExceptions"
+          middleware.delete ActionDispatch::ShowExceptions
         end
 
         yield
diff --git a/actionpack/test/controller/force_ssl_test.rb b/actionpack/test/controller/force_ssl_test.rb
index 00d4612ac9..22f1cc7c22 100644
--- a/actionpack/test/controller/force_ssl_test.rb
+++ b/actionpack/test/controller/force_ssl_test.rb
@@ -2,11 +2,11 @@ require 'abstract_unit'
 
 class ForceSSLController < ActionController::Base
   def banana
-    render :text => "monkey"
+    render plain: "monkey"
   end
 
   def cheeseburger
-    render :text => "sikachu"
+    render plain: "sikachu"
   end
 end
 
@@ -26,7 +26,7 @@ class ForceSSLCustomOptions < ForceSSLController
   force_ssl :notice => 'Foo, Bar!', :only => :redirect_notice
 
   def force_ssl_action
-    render :text => action_name
+    render plain: action_name
   end
 
   alias_method :redirect_host, :force_ssl_action
@@ -40,15 +40,15 @@ class ForceSSLCustomOptions < ForceSSLController
   alias_method :redirect_notice, :force_ssl_action
 
   def use_flash
-    render :text => flash[:message]
+    render plain: flash[:message]
   end
 
   def use_alert
-    render :text => flash[:alert]
+    render plain: flash[:alert]
   end
 
   def use_notice
-    render :text => flash[:notice]
+    render plain: flash[:notice]
   end
 end
 
@@ -85,10 +85,10 @@ end
 
 class RedirectToSSL < ForceSSLController
   def banana
-    force_ssl_redirect || render(:text => 'monkey')
+    force_ssl_redirect || render(plain: 'monkey')
   end
   def cheeseburger
-    force_ssl_redirect('secure.cheeseburger.host') || render(:text => 'ihaz')
+    force_ssl_redirect('secure.cheeseburger.host') || render(plain: 'ihaz')
   end
 end
 
@@ -100,7 +100,7 @@ class ForceSSLControllerLevelTest < ActionController::TestCase
   end
 
   def test_banana_redirects_to_https_with_extra_params
-    get :banana, :token => "secret"
+    get :banana, params: { token: "secret" }
     assert_response 301
     assert_equal "https://test.host/force_ssl_controller_level/banana?token=secret", redirect_to_url
   end
@@ -240,8 +240,8 @@ class ForceSSLFlashTest < ActionController::TestCase
     @request.env.delete('PATH_INFO')
 
     get :use_flash
-    assert_equal "hello", assigns["flash_copy"]["that"]
-    assert_equal "hello", assigns["flashy"]
+    assert_equal "hello", @controller.instance_variable_get("@flash_copy")["that"]
+    assert_equal "hello", @controller.instance_variable_get("@flashy")
   end
 end
 
@@ -273,7 +273,7 @@ class ForceSSLFormatTest < ActionController::TestCase
         get '/foo', :to => 'force_ssl_controller_level#banana'
       end
 
-      get :banana, :format => :json
+      get :banana, format: :json
       assert_response 301
       assert_equal 'https://test.host/foo.json', redirect_to_url
     end
@@ -294,7 +294,7 @@ class ForceSSLOptionalSegmentsTest < ActionController::TestCase
       end
 
       @request.env['PATH_INFO'] = '/en/foo'
-      get :banana, :locale => 'en'
+      get :banana, params: { locale: 'en' }
       assert_equal 'en',  @controller.params[:locale]
       assert_response 301
       assert_equal 'https://test.host/en/foo', redirect_to_url
@@ -315,7 +315,7 @@ class RedirectToSSLTest < ActionController::TestCase
     assert_equal "https://secure.cheeseburger.host/redirect_to_ssl/cheeseburger", redirect_to_url
   end
 
-  def test_banana_does_not_redirect_if_already_https
+  def test_cheeseburgers_does_not_redirect_if_already_https
     request.env['HTTPS'] = 'on'
     get :cheeseburger
     assert_response 200
diff --git a/actionpack/test/controller/form_builder_test.rb b/actionpack/test/controller/form_builder_test.rb
new file mode 100644
index 0000000000..99eeaf9ab6
--- /dev/null
+++ b/actionpack/test/controller/form_builder_test.rb
@@ -0,0 +1,17 @@
+require 'abstract_unit'
+
+class FormBuilderController < ActionController::Base
+  class SpecializedFormBuilder < ActionView::Helpers::FormBuilder ; end
+
+  default_form_builder SpecializedFormBuilder
+end
+
+class ControllerFormBuilderTest < ActiveSupport::TestCase
+  setup do
+    @controller = FormBuilderController.new
+  end
+
+  def test_default_form_builder_assigned
+    assert_equal FormBuilderController::SpecializedFormBuilder, @controller.default_form_builder
+  end
+end
diff --git a/actionpack/test/controller/helper_test.rb b/actionpack/test/controller/helper_test.rb
index 936b8c2450..3ecfedefd1 100644
--- a/actionpack/test/controller/helper_test.rb
+++ b/actionpack/test/controller/helper_test.rb
@@ -29,7 +29,7 @@ module ImpressiveLibrary
   def useful_function() end
 end
 
-ActionController::Base.send :include, ImpressiveLibrary
+ActionController::Base.include(ImpressiveLibrary)
 
 class JustMeController < ActionController::Base
   clear_helpers
@@ -73,14 +73,8 @@ module LocalAbcHelper
 end
 
 class HelperPathsTest < ActiveSupport::TestCase
-  def setup
-    @request    = ActionController::TestRequest.new
-    @response   = ActionController::TestResponse.new
-  end
-
   def test_helpers_paths_priority
-    request  = ActionController::TestRequest.new
-    responses = HelpersPathsController.action(:index).call(request.env)
+    responses = HelpersPathsController.action(:index).call(ActionController::TestRequest::DEFAULT_ENV.dup)
 
     # helpers1_pack was given as a second path, so pack1_helper should be
     # included as the second one
@@ -141,8 +135,7 @@ class HelperTest < ActiveSupport::TestCase
   end
 
   def call_controller(klass, action)
-    request  = ActionController::TestRequest.new
-    klass.action(action).call(request.env)
+    klass.action(action).call(ActionController::TestRequest::DEFAULT_ENV.dup)
   end
 
   def test_helper_for_nested_controller
@@ -158,7 +151,7 @@ class HelperTest < ActiveSupport::TestCase
     assert_equal "test: baz", call_controller(Fun::PdfController, "test").last.body
     #
     # request  = ActionController::TestRequest.new
-    # response = ActionController::TestResponse.new
+    # response = ActionDispatch::TestResponse.new
     # request.action = 'test'
     #
     # assert_equal 'test: baz', Fun::PdfController.process(request, response).body
@@ -223,10 +216,10 @@ class HelperTest < ActiveSupport::TestCase
     # fun/pdf_helper.rb
     assert methods.include?(:foobar)
   end
-  
+
   def test_helper_proxy_config
     AllHelpersController.config.my_var = 'smth'
-    
+
     assert_equal 'smth', AllHelpersController.helpers.config.my_var
   end
 
@@ -249,7 +242,7 @@ class HelperTest < ActiveSupport::TestCase
 end
 
 
-class IsolatedHelpersTest < ActiveSupport::TestCase
+class IsolatedHelpersTest < ActionController::TestCase
   class A < ActionController::Base
     def index
       render :inline => '<%= shout %>'
@@ -273,13 +266,11 @@ class IsolatedHelpersTest < ActiveSupport::TestCase
   end
 
   def call_controller(klass, action)
-    request  = ActionController::TestRequest.new
-    klass.action(action).call(request.env)
+    klass.action(action).call(@request.env)
   end
 
   def setup
-    @request    = ActionController::TestRequest.new
-    @response   = ActionController::TestResponse.new
+    super
     @request.action = 'index'
   end
 
diff --git a/actionpack/test/controller/http_basic_authentication_test.rb b/actionpack/test/controller/http_basic_authentication_test.rb
index 9052fc6962..0a5e5402b9 100644
--- a/actionpack/test/controller/http_basic_authentication_test.rb
+++ b/actionpack/test/controller/http_basic_authentication_test.rb
@@ -9,19 +9,19 @@ class HttpBasicAuthenticationTest < ActionController::TestCase
     http_basic_authenticate_with :name => "David", :password => "Goliath", :only => :search
 
     def index
-      render :text => "Hello Secret"
+      render plain: "Hello Secret"
     end
 
     def display
-      render :text => 'Definitely Maybe'
+      render plain: 'Definitely Maybe' if @logged_in
     end
 
     def show
-      render :text => 'Only for loooooong credentials'
+      render plain: 'Only for loooooong credentials'
     end
 
     def search
-      render :text => 'All inline'
+      render plain: 'All inline'
     end
 
     private
@@ -36,7 +36,7 @@ class HttpBasicAuthenticationTest < ActionController::TestCase
       if authenticate_with_http_basic { |username, password| username == 'pretty' && password == 'please' }
         @logged_in = true
       else
-        request_http_basic_authentication("SuperSecret")
+        request_http_basic_authentication("SuperSecret", "Authentication Failed\n")
       end
     end
 
@@ -83,6 +83,13 @@ class HttpBasicAuthenticationTest < ActionController::TestCase
       assert_response :unauthorized
       assert_equal "HTTP Basic: Access denied.\n", @response.body, "Authentication didn't fail for request header #{header} and long credentials"
     end
+
+    test "unsuccessful authentication with #{header.downcase} and no credentials" do
+      get :show
+
+      assert_response :unauthorized
+      assert_equal "HTTP Basic: Access denied.\n", @response.body, "Authentication didn't fail for request header #{header} and no credentials"
+    end
   end
 
   def test_encode_credentials_has_no_newline
@@ -93,11 +100,19 @@ class HttpBasicAuthenticationTest < ActionController::TestCase
     assert_no_match(/\n/, result)
   end
 
+  test "succesful authentication with uppercase authorization scheme" do
+    @request.env['HTTP_AUTHORIZATION'] = "BASIC #{::Base64.encode64("lifo:world")}"
+    get :index
+
+    assert_response :success
+    assert_equal 'Hello Secret', @response.body, 'Authentication failed when authorization scheme BASIC'
+  end
+
   test "authentication request without credential" do
     get :display
 
     assert_response :unauthorized
-    assert_equal "HTTP Basic: Access denied.\n", @response.body
+    assert_equal "Authentication Failed\n", @response.body
     assert_equal 'Basic realm="SuperSecret"', @response.headers['WWW-Authenticate']
   end
 
@@ -106,7 +121,7 @@ class HttpBasicAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :unauthorized
-    assert_equal "HTTP Basic: Access denied.\n", @response.body
+    assert_equal "Authentication Failed\n", @response.body
     assert_equal 'Basic realm="SuperSecret"', @response.headers['WWW-Authenticate']
   end
 
@@ -115,7 +130,6 @@ class HttpBasicAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
diff --git a/actionpack/test/controller/http_digest_authentication_test.rb b/actionpack/test/controller/http_digest_authentication_test.rb
index 52a0bc9aa3..f06912bd5a 100644
--- a/actionpack/test/controller/http_digest_authentication_test.rb
+++ b/actionpack/test/controller/http_digest_authentication_test.rb
@@ -10,11 +10,11 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
               'dhh' => ::Digest::MD5::hexdigest(["dhh","SuperSecret","secret"].join(":"))}
 
     def index
-      render :text => "Hello Secret"
+      render plain: "Hello Secret"
     end
 
     def display
-      render :text => 'Definitely Maybe'
+      render plain: 'Definitely Maybe' if @logged_in
     end
 
     private
@@ -124,7 +124,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
@@ -134,7 +133,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
@@ -144,7 +142,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
@@ -156,7 +153,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
@@ -167,7 +163,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
@@ -180,7 +175,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
@@ -191,7 +185,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
@@ -201,7 +194,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     put :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
@@ -244,7 +236,6 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :success
-    assert assigns(:logged_in)
     assert_equal 'Definitely Maybe', @response.body
   end
 
diff --git a/actionpack/test/controller/http_token_authentication_test.rb b/actionpack/test/controller/http_token_authentication_test.rb
index a758df2ec6..9c5a01c318 100644
--- a/actionpack/test/controller/http_token_authentication_test.rb
+++ b/actionpack/test/controller/http_token_authentication_test.rb
@@ -7,15 +7,15 @@ class HttpTokenAuthenticationTest < ActionController::TestCase
     before_action :authenticate_long_credentials, only: :show
 
     def index
-      render :text => "Hello Secret"
+      render plain: "Hello Secret"
     end
 
     def display
-      render :text => 'Definitely Maybe'
+      render plain: 'Definitely Maybe'
     end
 
     def show
-      render :text => 'Only for loooooong credentials'
+      render plain: 'Only for loooooong credentials'
     end
 
     private
@@ -30,7 +30,7 @@ class HttpTokenAuthenticationTest < ActionController::TestCase
       if authenticate_with_http_token { |token, options| token == '"quote" pretty' && options[:algorithm] == 'test' }
         @logged_in = true
       else
-        request_http_token_authentication("SuperSecret")
+        request_http_token_authentication("SuperSecret", "Authentication Failed\n")
       end
     end
 
@@ -80,18 +80,25 @@ class HttpTokenAuthenticationTest < ActionController::TestCase
   end
 
   test "authentication request with badly formatted header" do
-    @request.env['HTTP_AUTHORIZATION'] = "Token foobar"
+    @request.env['HTTP_AUTHORIZATION'] = 'Token token$"lifo"'
     get :index
 
     assert_response :unauthorized
     assert_equal "HTTP Token: Access denied.\n", @response.body, "Authentication header was not properly parsed"
   end
 
+  test "successful authentication request with Bearer instead of Token" do
+    @request.env['HTTP_AUTHORIZATION'] = 'Bearer lifo'
+    get :index
+
+    assert_response :success
+  end
+
   test "authentication request without credential" do
     get :display
 
     assert_response :unauthorized
-    assert_equal "HTTP Token: Access denied.\n", @response.body
+    assert_equal "Authentication Failed\n", @response.body
     assert_equal 'Token realm="SuperSecret"', @response.headers['WWW-Authenticate']
   end
 
@@ -100,7 +107,7 @@ class HttpTokenAuthenticationTest < ActionController::TestCase
     get :display
 
     assert_response :unauthorized
-    assert_equal "HTTP Token: Access denied.\n", @response.body
+    assert_equal "Authentication Failed\n", @response.body
     assert_equal 'Token realm="SuperSecret"', @response.headers['WWW-Authenticate']
   end
 
diff --git a/actionpack/test/controller/integration_test.rb b/actionpack/test/controller/integration_test.rb
index 5c0651bd73..d0a1d1285f 100644
--- a/actionpack/test/controller/integration_test.rb
+++ b/actionpack/test/controller/integration_test.rb
@@ -26,180 +26,341 @@ class SessionTest < ActiveSupport::TestCase
   end
 
   def test_follow_redirect_raises_when_no_redirect
-    @session.stubs(:redirect?).returns(false)
-    assert_raise(RuntimeError) { @session.follow_redirect! }
+    @session.stub :redirect?, false do
+      assert_raise(RuntimeError) { @session.follow_redirect! }
+    end
   end
 
   def test_request_via_redirect_uses_given_method
     path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue"}
-    @session.expects(:process).with(:put, path, args, headers)
-    @session.stubs(:redirect?).returns(false)
-    @session.request_via_redirect(:put, path, args, headers)
+    assert_called_with @session, :process, [:put, path, params: args, headers: headers] do
+      @session.stub :redirect?, false do
+        @session.request_via_redirect(:put, path, params: args, headers: headers)
+      end
+    end
+  end
+
+  def test_deprecated_request_via_redirect_uses_given_method
+    path = "/somepath"; args = { id: '1' }; headers = { "X-Test-Header" => "testvalue" }
+    assert_called_with @session, :process, [:put, path, params: args, headers: headers] do
+      @session.stub :redirect?, false do
+        assert_deprecated { @session.request_via_redirect(:put, path, args, headers) }
+      end
+    end
   end
 
   def test_request_via_redirect_follows_redirects
     path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue"}
-    @session.stubs(:redirect?).returns(true, true, false)
-    @session.expects(:follow_redirect!).times(2)
-    @session.request_via_redirect(:get, path, args, headers)
+    value_series = [true, true, false]
+    assert_called @session, :follow_redirect!, times: 2 do
+      @session.stub :redirect?, ->{ value_series.shift } do
+        @session.request_via_redirect(:get, path, params: args, headers: headers)
+      end
+    end
   end
 
   def test_request_via_redirect_returns_status
     path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue"}
-    @session.stubs(:redirect?).returns(false)
-    @session.stubs(:status).returns(200)
-    assert_equal 200, @session.request_via_redirect(:get, path, args, headers)
+    @session.stub :redirect?, false do
+      @session.stub :status, 200 do
+        assert_equal 200, @session.request_via_redirect(:get, path, params: args, headers: headers)
+      end
+    end
   end
 
-  def test_get_via_redirect
-    path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue" }
-    @session.expects(:request_via_redirect).with(:get, path, args, headers)
-    @session.get_via_redirect(path, args, headers)
+  def test_deprecated_get_via_redirect
+    path = "/somepath"; args = { id: '1' }; headers = { "X-Test-Header" => "testvalue" }
+
+    assert_called_with @session, :request_via_redirect, [:get, path, args, headers] do
+      assert_deprecated do
+        @session.get_via_redirect(path, args, headers)
+      end
+    end
   end
 
-  def test_post_via_redirect
-    path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue" }
-    @session.expects(:request_via_redirect).with(:post, path, args, headers)
-    @session.post_via_redirect(path, args, headers)
+  def test_deprecated_post_via_redirect
+    path = "/somepath"; args = { id: '1' }; headers = { "X-Test-Header" => "testvalue" }
+
+    assert_called_with @session, :request_via_redirect, [:post, path, args, headers] do
+      assert_deprecated do
+        @session.post_via_redirect(path, args, headers)
+      end
+    end
   end
 
-  def test_patch_via_redirect
-    path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue" }
-    @session.expects(:request_via_redirect).with(:patch, path, args, headers)
-    @session.patch_via_redirect(path, args, headers)
+  def test_deprecated_patch_via_redirect
+    path = "/somepath"; args = { id: '1' }; headers = { "X-Test-Header" => "testvalue" }
+
+    assert_called_with @session, :request_via_redirect, [:patch, path, args, headers] do
+      assert_deprecated do
+        @session.patch_via_redirect(path, args, headers)
+      end
+    end
   end
 
-  def test_put_via_redirect
-    path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue" }
-    @session.expects(:request_via_redirect).with(:put, path, args, headers)
-    @session.put_via_redirect(path, args, headers)
+  def test_deprecated_put_via_redirect
+    path = "/somepath"; args = { id: '1' }; headers = { "X-Test-Header" => "testvalue" }
+
+    assert_called_with @session, :request_via_redirect, [:put, path, args, headers] do
+      assert_deprecated do
+        @session.put_via_redirect(path, args, headers)
+      end
+    end
   end
 
-  def test_delete_via_redirect
-    path = "/somepath"; args = {:id => '1'}; headers = {"X-Test-Header" => "testvalue" }
-    @session.expects(:request_via_redirect).with(:delete, path, args, headers)
-    @session.delete_via_redirect(path, args, headers)
+  def test_deprecated_delete_via_redirect
+    path = "/somepath"; args = { id: '1' }; headers = { "X-Test-Header" => "testvalue" }
+
+    assert_called_with @session, :request_via_redirect, [:delete, path, args, headers] do
+      assert_deprecated do
+        @session.delete_via_redirect(path, args, headers)
+      end
+    end
   end
 
   def test_get
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    @session.expects(:process).with(:get,path,params,headers)
-    @session.get(path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+
+    assert_called_with @session, :process, [:get, path, params: params, headers: headers] do
+      @session.get(path, params: params, headers: headers)
+    end
+  end
+
+  def test_get_with_env_and_headers
+    path = "/index"; params = "blah"; headers = { location: 'blah' }; env = { 'HTTP_X_REQUESTED_WITH' => 'XMLHttpRequest' }
+    assert_called_with @session, :process, [:get, path, params: params, headers: headers, env: env] do
+      @session.get(path, params: params, headers: headers, env: env)
+    end
+  end
+
+  def test_deprecated_get
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+
+    assert_called_with @session, :process, [:get, path, params: params, headers: headers] do
+      assert_deprecated {
+        @session.get(path, params, headers)
+      }
+    end
   end
 
   def test_post
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    @session.expects(:process).with(:post,path,params,headers)
-    @session.post(path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:post, path, params: params, headers: headers] do
+      assert_deprecated {
+        @session.post(path, params, headers)
+      }
+    end
+  end
+
+  def test_deprecated_post
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:post, path, params: params, headers: headers] do
+      @session.post(path, params: params, headers: headers)
+    end
   end
 
   def test_patch
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    @session.expects(:process).with(:patch,path,params,headers)
-    @session.patch(path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:patch, path, params: params, headers: headers] do
+      @session.patch(path, params: params, headers: headers)
+    end
+  end
+
+  def test_deprecated_patch
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:patch, path, params: params, headers: headers] do
+      assert_deprecated {
+        @session.patch(path, params, headers)
+      }
+    end
   end
 
   def test_put
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    @session.expects(:process).with(:put,path,params,headers)
-    @session.put(path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:put, path, params: params, headers: headers] do
+      @session.put(path, params: params, headers: headers)
+    end
+  end
+
+  def test_deprecated_put
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:put, path, params: params, headers: headers] do
+      assert_deprecated {
+        @session.put(path, params, headers)
+      }
+    end
   end
 
   def test_delete
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    @session.expects(:process).with(:delete,path,params,headers)
-    @session.delete(path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:delete, path, params: params, headers: headers] do
+      assert_deprecated {
+        @session.delete(path,params,headers)
+      }
+    end
+  end
+
+  def test_deprecated_delete
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:delete, path, params: params, headers: headers] do
+      @session.delete(path, params: params, headers: headers)
+    end
   end
 
   def test_head
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    @session.expects(:process).with(:head,path,params,headers)
-    @session.head(path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:head, path, params: params, headers: headers] do
+      @session.head(path, params: params, headers: headers)
+    end
+  end
+
+  def deprecated_test_head
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:head, path, params: params, headers: headers] do
+      assert_deprecated {
+        @session.head(path, params, headers)
+      }
+    end
   end
 
   def test_xml_http_request_get
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    headers_after_xhr = headers.merge(
-      "HTTP_X_REQUESTED_WITH" => "XMLHttpRequest",
-      "HTTP_ACCEPT"           => "text/javascript, text/html, application/xml, text/xml, */*"
-    )
-    @session.expects(:process).with(:get,path,params,headers_after_xhr)
-    @session.xml_http_request(:get,path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:get, path, params: params, headers: headers, xhr: true] do
+      @session.get(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_xml_http_request_get
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:get, path, params: params, headers: headers, xhr: true] do
+      @session.get(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_args_xml_http_request_get
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:get, path, params: params, headers: headers, xhr: true] do
+      assert_deprecated(/xml_http_request/) {
+        @session.xml_http_request(:get, path, params, headers)
+      }
+    end
   end
 
   def test_xml_http_request_post
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    headers_after_xhr = headers.merge(
-      "HTTP_X_REQUESTED_WITH" => "XMLHttpRequest",
-      "HTTP_ACCEPT"           => "text/javascript, text/html, application/xml, text/xml, */*"
-    )
-    @session.expects(:process).with(:post,path,params,headers_after_xhr)
-    @session.xml_http_request(:post,path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:post, path, params: params, headers: headers, xhr: true] do
+      @session.post(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_xml_http_request_post
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:post, path, params: params, headers: headers, xhr: true] do
+      @session.post(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_args_xml_http_request_post
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:post, path, params: params, headers: headers, xhr: true] do
+      assert_deprecated(/xml_http_request/) { @session.xml_http_request(:post,path,params,headers) }
+    end
   end
 
   def test_xml_http_request_patch
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    headers_after_xhr = headers.merge(
-      "HTTP_X_REQUESTED_WITH" => "XMLHttpRequest",
-      "HTTP_ACCEPT"           => "text/javascript, text/html, application/xml, text/xml, */*"
-    )
-    @session.expects(:process).with(:patch,path,params,headers_after_xhr)
-    @session.xml_http_request(:patch,path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:patch, path, params: params, headers: headers, xhr: true] do
+      @session.patch(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_xml_http_request_patch
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:patch, path, params: params, headers: headers, xhr: true] do
+      @session.patch(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_args_xml_http_request_patch
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:patch, path, params: params, headers: headers, xhr: true] do
+      assert_deprecated(/xml_http_request/) { @session.xml_http_request(:patch,path,params,headers) }
+    end
   end
 
   def test_xml_http_request_put
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    headers_after_xhr = headers.merge(
-      "HTTP_X_REQUESTED_WITH" => "XMLHttpRequest",
-      "HTTP_ACCEPT"           => "text/javascript, text/html, application/xml, text/xml, */*"
-    )
-    @session.expects(:process).with(:put,path,params,headers_after_xhr)
-    @session.xml_http_request(:put,path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:put, path, params: params, headers: headers, xhr: true] do
+      @session.put(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_xml_http_request_put
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:put, path, params: params, headers: headers, xhr: true] do
+      @session.put(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_args_xml_http_request_put
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:put, path, params: params, headers: headers, xhr: true] do
+      assert_deprecated(/xml_http_request/) { @session.xml_http_request(:put, path, params, headers) }
+    end
   end
 
   def test_xml_http_request_delete
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    headers_after_xhr = headers.merge(
-      "HTTP_X_REQUESTED_WITH" => "XMLHttpRequest",
-      "HTTP_ACCEPT"           => "text/javascript, text/html, application/xml, text/xml, */*"
-    )
-    @session.expects(:process).with(:delete,path,params,headers_after_xhr)
-    @session.xml_http_request(:delete,path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:delete, path, params: params, headers: headers, xhr: true] do
+      @session.delete(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_xml_http_request_delete
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:delete, path, params: params, headers: headers, xhr: true] do
+      assert_deprecated { @session.xml_http_request(:delete, path, params: params, headers: headers) }
+    end
+  end
+
+  def test_deprecated_args_xml_http_request_delete
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:delete, path, params: params, headers: headers, xhr: true] do
+      assert_deprecated(/xml_http_request/) { @session.xml_http_request(:delete, path, params, headers) }
+    end
   end
 
   def test_xml_http_request_head
-    path = "/index"; params = "blah"; headers = {:location => 'blah'}
-    headers_after_xhr = headers.merge(
-      "HTTP_X_REQUESTED_WITH" => "XMLHttpRequest",
-      "HTTP_ACCEPT"           => "text/javascript, text/html, application/xml, text/xml, */*"
-    )
-    @session.expects(:process).with(:head,path,params,headers_after_xhr)
-    @session.xml_http_request(:head,path,params,headers)
-  end
-
-  def test_xml_http_request_override_accept
-    path = "/index"; params = "blah"; headers = {:location => 'blah', "HTTP_ACCEPT" => "application/xml"}
-    headers_after_xhr = headers.merge(
-      "HTTP_X_REQUESTED_WITH" => "XMLHttpRequest"
-    )
-    @session.expects(:process).with(:post,path,params,headers_after_xhr)
-    @session.xml_http_request(:post,path,params,headers)
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:head, path, params: params, headers: headers, xhr: true] do
+      @session.head(path, params: params, headers: headers, xhr: true)
+    end
+  end
+
+  def test_deprecated_xml_http_request_head
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:head, path, params: params, headers: headers, xhr: true] do
+      assert_deprecated(/xml_http_request/) { @session.xml_http_request(:head, path, params: params, headers: headers) }
+    end
+  end
+
+  def test_deprecated_args_xml_http_request_head
+    path = "/index"; params = "blah"; headers = { location: 'blah' }
+    assert_called_with @session, :process, [:head, path, params: params, headers: headers, xhr: true] do
+      assert_deprecated { @session.xml_http_request(:head, path, params, headers) }
+    end
   end
 end
 
 class IntegrationTestTest < ActiveSupport::TestCase
   def setup
     @test = ::ActionDispatch::IntegrationTest.new(:app)
-    @test.class.stubs(:fixture_table_names).returns([])
-    @session = @test.open_session
   end
 
   def test_opens_new_session
     session1 = @test.open_session { |sess| }
     session2 = @test.open_session # implicit session
 
-    assert_respond_to session1, :assert_template, "open_session makes assert_template available"
-    assert_respond_to session2, :assert_template, "open_session makes assert_template available"
     assert !session1.equal?(session2)
   end
 
@@ -225,14 +386,8 @@ end
 # Tests that integration tests don't call Controller test methods for processing.
 # Integration tests have their own setup and teardown.
 class IntegrationTestUsesCorrectClass < ActionDispatch::IntegrationTest
-  def self.fixture_table_names
-    []
-  end
-
   def test_integration_methods_called
     reset!
-    @integration_session.stubs(:generic_url_rewriter)
-    @integration_session.stubs(:process)
 
     %w( get post head patch put delete ).each do |verb|
       assert_nothing_raised("'#{verb}' should use integration test methods") { __send__(verb, '/') }
@@ -244,27 +399,30 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
   class IntegrationController < ActionController::Base
     def get
       respond_to do |format|
-        format.html { render :text => "OK", :status => 200 }
-        format.js { render :text => "JS OK", :status => 200 }
+        format.html { render plain: "OK", status: 200 }
+        format.js { render plain: "JS OK", status: 200 }
+        format.xml { render :xml => "<root></root>", :status => 200 }
+        format.rss { render :xml => "<root></root>", :status => 200 }
+        format.atom { render :xml => "<root></root>", :status => 200 }
       end
     end
 
     def get_with_params
-      render :text => "foo: #{params[:foo]}", :status => 200
+      render plain: "foo: #{params[:foo]}", status: 200
     end
 
     def post
-      render :text => "Created", :status => 201
+      render plain: "Created", status: 201
     end
 
     def method
-      render :text => "method: #{request.method.downcase}"
+      render plain: "method: #{request.method.downcase}"
     end
 
     def cookie_monster
       cookies["cookie_1"] = nil
       cookies["cookie_3"] = "chocolate"
-      render :text => "Gone", :status => 410
+      render plain: "Gone", status: 410
     end
 
     def set_cookie
@@ -273,16 +431,16 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
     end
 
     def get_cookie
-      render :text => cookies["foo"]
+      render plain: cookies["foo"]
     end
 
     def redirect
       redirect_to action_url('get')
     end
 
-    def remove_default_header
-      response.headers.except! 'X-Frame-Options'
-      head :ok
+    def remove_header
+      response.headers.delete params[:header]
+      head :ok, 'c' => '3'
     end
   end
 
@@ -302,6 +460,24 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
     end
   end
 
+  def test_get_xml_rss_atom
+    %w[ application/xml application/rss+xml application/atom+xml ].each do |mime_string|
+      with_test_route_set do
+        get "/get", headers: {"HTTP_ACCEPT" => mime_string}
+        assert_equal 200, status
+        assert_equal "OK", status_message
+        assert_response 200
+        assert_response :success
+        assert_response :ok
+        assert_equal({}, cookies.to_hash)
+        assert_equal "<root></root>", body
+        assert_equal "<root></root>", response.body
+        assert_instance_of Nokogiri::XML::Document, html_document
+        assert_equal 1, request_count
+      end
+    end
+  end
+
   def test_post
     with_test_route_set do
       post '/post'
@@ -388,7 +564,19 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
 
   def test_xml_http_request_get
     with_test_route_set do
-      xhr :get, '/get'
+      get '/get', xhr: true
+      assert_equal 200, status
+      assert_equal "OK", status_message
+      assert_response 200
+      assert_response :success
+      assert_response :ok
+      assert_equal "JS OK", response.body
+    end
+  end
+
+  def test_deprecated_xml_http_request_get
+    with_test_route_set do
+      assert_deprecated { xhr :get, '/get' }
       assert_equal 200, status
       assert_equal "OK", status_message
       assert_response 200
@@ -400,7 +588,7 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
 
   def test_request_with_bad_format
     with_test_route_set do
-      xhr :get, '/get.php'
+      get '/get.php', xhr: true
       assert_equal 406, status
       assert_response 406
       assert_response :not_acceptable
@@ -423,7 +611,7 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
 
   def test_get_with_parameters
     with_test_route_set do
-      get '/get_with_params', :foo => "bar"
+      get '/get_with_params', params: { foo: "bar" }
       assert_equal '/get_with_params', request.env["PATH_INFO"]
       assert_equal '/get_with_params', request.path_info
       assert_equal 'foo=bar', request.env["QUERY_STRING"]
@@ -511,25 +699,27 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
     end
   end
 
-  def test_removed_default_headers_on_test_response_are_not_reapplied
+  def test_respect_removal_of_default_headers_by_a_controller_action
     with_test_route_set do
-      begin
-        header_to_remove = 'X-Frame-Options'
-        original_default_headers = ActionDispatch::Response.default_headers
-        ActionDispatch::Response.default_headers = {
-          'X-Content-Type-Options' => 'nosniff',
-          header_to_remove => 'SAMEORIGIN',
-        }
-        get '/remove_default_header'
-        assert_includes headers, 'X-Content-Type-Options'
-        assert_not_includes headers, header_to_remove, "Should not contain removed default header"
-      ensure
-        ActionDispatch::Response.default_headers = original_default_headers
+      with_default_headers 'a' => '1', 'b' => '2' do
+        get '/remove_header', params: { header: 'a' }
       end
     end
+
+    assert_not_includes @response.headers, 'a', 'Response should not include default header removed by the controller action'
+    assert_includes @response.headers, 'b'
+    assert_includes @response.headers, 'c'
   end
 
   private
+    def with_default_headers(headers)
+      original = ActionDispatch::Response.default_headers
+      ActionDispatch::Response.default_headers = headers
+      yield
+    ensure
+      ActionDispatch::Response.default_headers = original
+    end
+
     def with_test_route_set
       with_routing do |set|
         controller = ::IntegrationProcessTest::IntegrationController.clone
@@ -544,7 +734,7 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
           get 'get/:action', :to => controller, :as => :get_action
         end
 
-        self.singleton_class.send(:include, set.url_helpers)
+        self.singleton_class.include(set.url_helpers)
 
         yield
       end
@@ -588,25 +778,52 @@ class MetalIntegrationTest < ActionDispatch::IntegrationTest
   end
 
   def test_pass_headers
-    get "/success", {}, "Referer" => "http://www.example.com/foo", "Host" => "http://nohost.com"
+    get "/success", headers: {"Referer" => "http://www.example.com/foo", "Host" => "http://nohost.com"}
 
     assert_equal "http://nohost.com", @request.env["HTTP_HOST"]
     assert_equal "http://www.example.com/foo", @request.env["HTTP_REFERER"]
   end
 
+  def test_pass_headers_and_env
+    get "/success", headers: { "X-Test-Header" => "value" }, env: { "HTTP_REFERER" => "http://test.com/", "HTTP_HOST" => "http://test.com" }
+
+    assert_equal "http://test.com", @request.env["HTTP_HOST"]
+    assert_equal "http://test.com/", @request.env["HTTP_REFERER"]
+    assert_equal "value", @request.env["HTTP_X_TEST_HEADER"]
+  end
+
   def test_pass_env
-    get "/success", {}, "HTTP_REFERER" => "http://test.com/", "HTTP_HOST" => "http://test.com"
+    get "/success", env: { "HTTP_REFERER" => "http://test.com/", "HTTP_HOST" => "http://test.com" }
 
     assert_equal "http://test.com", @request.env["HTTP_HOST"]
     assert_equal "http://test.com/", @request.env["HTTP_REFERER"]
   end
 
+  def test_ignores_common_ports_in_host
+    get "http://test.com"
+    assert_equal "test.com", @request.env["HTTP_HOST"]
+
+    get "https://test.com"
+    assert_equal "test.com", @request.env["HTTP_HOST"]
+  end
+
+  def test_keeps_uncommon_ports_in_host
+    get "http://test.com:123"
+    assert_equal "test.com:123", @request.env["HTTP_HOST"]
+
+    get "http://test.com:443"
+    assert_equal "test.com:443", @request.env["HTTP_HOST"]
+
+    get "https://test.com:80"
+    assert_equal "test.com:80", @request.env["HTTP_HOST"]
+  end
+
 end
 
 class ApplicationIntegrationTest < ActionDispatch::IntegrationTest
   class TestController < ActionController::Base
     def index
-      render :text => "index"
+      render plain: "index"
     end
   end
 
@@ -685,7 +902,7 @@ class ApplicationIntegrationTest < ActionDispatch::IntegrationTest
   test "process do not modify the env passed as argument" do
     env = { :SERVER_NAME => 'server', 'action_dispatch.custom' => 'custom' }
     old_env = env.dup
-    get '/foo', nil, env
+    get '/foo', env: env
     assert_equal old_env, env
   end
 end
@@ -693,7 +910,7 @@ end
 class EnvironmentFilterIntegrationTest < ActionDispatch::IntegrationTest
   class TestController < ActionController::Base
     def post
-      render :text => "Created", :status => 201
+      render plain: "Created", status: 201
     end
   end
 
@@ -715,7 +932,7 @@ class EnvironmentFilterIntegrationTest < ActionDispatch::IntegrationTest
   end
 
   test "filters rack request form vars" do
-    post "/post", :username => 'cjolly', :password => 'secret'
+    post "/post", params: { username: 'cjolly', password: 'secret' }
 
     assert_equal 'cjolly', request.filtered_parameters['username']
     assert_equal '[FILTERED]', request.filtered_parameters['password']
@@ -726,15 +943,15 @@ end
 class UrlOptionsIntegrationTest < ActionDispatch::IntegrationTest
   class FooController < ActionController::Base
     def index
-      render :text => "foo#index"
+      render plain: "foo#index"
     end
 
     def show
-      render :text => "foo#show"
+      render plain: "foo#show"
     end
 
     def edit
-      render :text => "foo#show"
+      render plain: "foo#show"
     end
   end
 
@@ -744,7 +961,7 @@ class UrlOptionsIntegrationTest < ActionDispatch::IntegrationTest
     end
 
     def index
-      render :text => "foo#index"
+      render plain: "foo#index"
     end
   end
 
@@ -897,3 +1114,15 @@ class IntegrationRequestsWithoutSetup < ActionDispatch::IntegrationTest
     end
   end
 end
+
+# to ensure that session requirements in setup are persisted in the tests
+class IntegrationRequestsWithSessionSetup < ActionDispatch::IntegrationTest
+  setup do
+    cookies['user_name'] = 'david'
+  end
+
+  def test_cookies_set_in_setup_are_persisted_through_the_session
+    get "/foo"
+    assert_equal({"user_name"=>"david"}, cookies.to_hash)
+  end
+end
diff --git a/actionpack/test/controller/live_stream_test.rb b/actionpack/test/controller/live_stream_test.rb
index 7fd1276e98..4224ac2a1b 100644
--- a/actionpack/test/controller/live_stream_test.rb
+++ b/actionpack/test/controller/live_stream_test.rb
@@ -1,5 +1,5 @@
 require 'abstract_unit'
-require 'active_support/concurrency/latch'
+require 'concurrent/atomics'
 Thread.abort_on_exception = true
 
 module ActionController
@@ -112,7 +112,7 @@ module ActionController
     class TestController < ActionController::Base
       include ActionController::Live
 
-      attr_accessor :latch, :tc
+      attr_accessor :latch, :tc, :error_latch
 
       def self.controller_path
         'test'
@@ -125,7 +125,7 @@ module ActionController
       end
 
       def render_text
-        render :text => 'zomg'
+        render plain: 'zomg'
       end
 
       def default_header
@@ -145,7 +145,7 @@ module ActionController
         response.headers['Content-Type'] = 'text/event-stream'
         %w{ hello world }.each do |word|
           response.stream.write word
-          latch.await
+          latch.wait
         end
         response.stream.close
       end
@@ -162,7 +162,7 @@ module ActionController
       end
 
       def with_stale
-        render text: 'stale' if stale?(etag: "123", template: false)
+        render plain: 'stale' if stale?(etag: "123", template: false)
       end
 
       def exception_in_view
@@ -204,6 +204,12 @@ module ActionController
       end
 
       def overfill_buffer_and_die
+        logger = ActionController::Base.logger || Logger.new($stdout)
+        response.stream.on_error do
+          logger.warn 'Error while streaming'
+          error_latch.count_down
+        end
+
         # Write until the buffer is full. It doesn't expose that
         # information directly, so we must hard-code its size:
         10.times do
@@ -212,7 +218,7 @@ module ActionController
         # .. plus one more, because the #each frees up a slot:
         response.stream.write '.'
 
-        latch.release
+        latch.count_down
 
         # This write will block, and eventually raise
         response.stream.write 'x'
@@ -233,7 +239,7 @@ module ActionController
         end
 
         logger.info 'Work complete'
-        latch.release
+        latch.count_down
       end
     end
 
@@ -256,98 +262,79 @@ module ActionController
     end
 
     def test_set_cookie
-      @controller = TestController.new
       get :set_cookie
       assert_equal({'hello' => 'world'}, @response.cookies)
       assert_equal "hello world", @response.body
     end
 
-    def test_set_response!
-      @controller.set_response!(@request)
-      assert_kind_of(Live::Response, @controller.response)
-      assert_equal @request, @controller.response.request
-    end
-
     def test_write_to_stream
-      @controller = TestController.new
       get :basic_stream
       assert_equal "helloworld", @response.body
       assert_equal 'text/event-stream', @response.headers['Content-Type']
     end
 
     def test_async_stream
-      @controller.latch = ActiveSupport::Concurrency::Latch.new
+      rubinius_skip "https://github.com/rubinius/rubinius/issues/2934"
+
+      @controller.latch = Concurrent::CountDownLatch.new
       parts             = ['hello', 'world']
 
-      @controller.request  = @request
-      @controller.response = @response
+      get :blocking_stream
 
-      t = Thread.new(@response) { |resp|
+      t = Thread.new(response) { |resp|
         resp.await_commit
         resp.stream.each do |part|
           assert_equal parts.shift, part
           ol = @controller.latch
-          @controller.latch = ActiveSupport::Concurrency::Latch.new
-          ol.release
+          @controller.latch = Concurrent::CountDownLatch.new
+          ol.count_down
         end
       }
 
-      @controller.process :blocking_stream
-
       assert t.join(3), 'timeout expired before the thread terminated'
     end
 
     def test_abort_with_full_buffer
-      @controller.latch = ActiveSupport::Concurrency::Latch.new
-
-      @request.parameters[:format] = 'plain'
-      @controller.request  = @request
-      @controller.response = @response
-
-      got_error = ActiveSupport::Concurrency::Latch.new
-      @response.stream.on_error do
-        ActionController::Base.logger.warn 'Error while streaming'
-        got_error.release
-      end
-
-      t = Thread.new(@response) { |resp|
-        resp.await_commit
-        _, _, body = resp.to_a
-        body.each do |part|
-          @controller.latch.await
-          body.close
-          break
-        end
-      }
+      @controller.latch = Concurrent::CountDownLatch.new
+      @controller.error_latch = Concurrent::CountDownLatch.new
 
       capture_log_output do |output|
-        @controller.process :overfill_buffer_and_die
+        get :overfill_buffer_and_die, :format => 'plain'
+
+        t = Thread.new(response) { |resp|
+          resp.await_commit
+          _, _, body = resp.to_a
+          body.each do
+            @controller.latch.wait
+            body.close
+            break
+          end
+        }
+
         t.join
-        got_error.await
+        @controller.error_latch.wait
         assert_match 'Error while streaming', output.rewind && output.read
       end
     end
 
     def test_ignore_client_disconnect
-      @controller.latch = ActiveSupport::Concurrency::Latch.new
+      @controller.latch = Concurrent::CountDownLatch.new
 
-      @controller.request  = @request
-      @controller.response = @response
+      capture_log_output do |output|
+        get :ignore_client_disconnect
 
-      t = Thread.new(@response) { |resp|
-        resp.await_commit
-        _, _, body = resp.to_a
-        body.each do |part|
-          body.close
-          break
-        end
-      }
+        t = Thread.new(response) { |resp|
+          resp.await_commit
+          _, _, body = resp.to_a
+          body.each do
+            body.close
+            break
+          end
+        }
 
-      capture_log_output do |output|
-        @controller.process :ignore_client_disconnect
         t.join
         Timeout.timeout(3) do
-          @controller.latch.await
+          @controller.latch.wait
         end
         assert_match 'Work complete', output.rewind && output.read
       end
@@ -362,11 +349,8 @@ module ActionController
     end
 
     def test_live_stream_default_header
-      @controller.request  = @request
-      @controller.response = @response
-      @controller.process :default_header
-      _, headers, _ = @response.prepare!
-      assert headers['Content-Type']
+      get :default_header
+      assert response.headers['Content-Type']
     end
 
     def test_render_text
@@ -404,8 +388,14 @@ module ActionController
     end
 
     def test_exception_callback_when_committed
+      current_threads = Thread.list
+
       capture_log_output do |output|
         get :exception_with_callback, format: 'text/event-stream'
+
+        # Wait on the execution of all threads
+        (Thread.list - current_threads).each(&:join)
+
         assert_equal %(data: "500 Internal Server Error"\n\n), response.body
         assert_match 'An exception occurred...', output.rewind && output.read
         assert_stream_closed
@@ -435,13 +425,13 @@ module ActionController
 
     def test_stale_without_etag
       get :with_stale
-      assert_equal 200, @response.status.to_i
+      assert_equal 200, response.status.to_i
     end
 
     def test_stale_with_etag
       @request.if_none_match = Digest::MD5.hexdigest("123")
       get :with_stale
-      assert_equal 304, @response.status.to_i
+      assert_equal 304, response.status.to_i
     end
   end
 
diff --git a/actionpack/test/controller/localized_templates_test.rb b/actionpack/test/controller/localized_templates_test.rb
index 2be947c648..3576015513 100644
--- a/actionpack/test/controller/localized_templates_test.rb
+++ b/actionpack/test/controller/localized_templates_test.rb
@@ -30,7 +30,7 @@ class LocalizedTemplatesTest < ActionController::TestCase
 
   def test_use_fallback_locales
     I18n.locale = :"de-AT"
-    I18n.backend.class.send(:include, I18n::Backend::Fallbacks)
+    I18n.backend.class.include(I18n::Backend::Fallbacks)
     I18n.fallbacks[:"de-AT"] = [:de]
 
     get :hello_world
diff --git a/actionpack/test/controller/log_subscriber_test.rb b/actionpack/test/controller/log_subscriber_test.rb
index 864c6ee130..7835d2768a 100644
--- a/actionpack/test/controller/log_subscriber_test.rb
+++ b/actionpack/test/controller/log_subscriber_test.rb
@@ -10,7 +10,7 @@ module Another
     end
 
     rescue_from SpecialException do
-      head :status => 406
+      head 406
     end
 
     before_action :redirector, only: :never_executed
@@ -19,7 +19,7 @@ module Another
     end
 
     def show
-      render :nothing => true
+      head :ok
     end
 
     def redirector
@@ -140,7 +140,7 @@ class ACLogSubscriberTest < ActionController::TestCase
   end
 
   def test_process_action_with_parameters
-    get :show, :id => '10'
+    get :show, params: { id: '10' }
     wait
 
     assert_equal 3, logs.size
@@ -148,8 +148,8 @@ class ACLogSubscriberTest < ActionController::TestCase
   end
 
   def test_multiple_process_with_parameters
-    get :show, :id => '10'
-    get :show, :id => '20'
+    get :show, params: { id: '10' }
+    get :show, params: { id: '20' }
 
     wait
 
@@ -160,7 +160,7 @@ class ACLogSubscriberTest < ActionController::TestCase
 
   def test_process_action_with_wrapped_parameters
     @request.env['CONTENT_TYPE'] = 'application/json'
-    post :show, :id => '10', :name => 'jose'
+    post :show, params: { id: '10', name: 'jose' }
     wait
 
     assert_equal 3, logs.size
@@ -170,7 +170,7 @@ class ACLogSubscriberTest < ActionController::TestCase
   def test_process_action_with_view_runtime
     get :show
     wait
-    assert_match(/\(Views: [\d.]+ms\)/, logs[1])
+    assert_match(/Completed 200 OK in [\d]ms/, logs[1])
   end
 
   def test_append_info_to_payload_is_called_even_with_exception
@@ -186,7 +186,9 @@ class ACLogSubscriberTest < ActionController::TestCase
   def test_process_action_with_filter_parameters
     @request.env["action_dispatch.parameter_filter"] = [:lifo, :amount]
 
-    get :show, :lifo => 'Pratik', :amount => '420', :step => '1'
+    get :show, params: {
+      lifo: 'Pratik', amount: '420', step: '1'
+    }
     wait
 
     params = logs[1]
diff --git a/actionpack/test/controller/mime/accept_format_test.rb b/actionpack/test/controller/mime/accept_format_test.rb
index 811c507af2..e20c08da4e 100644
--- a/actionpack/test/controller/mime/accept_format_test.rb
+++ b/actionpack/test/controller/mime/accept_format_test.rb
@@ -11,7 +11,7 @@ end
 class StarStarMimeControllerTest < ActionController::TestCase
   def test_javascript_with_format
     @request.accept = "text/javascript"
-    get :index, :format => 'js'
+    get :index, format: 'js'
     assert_match "function addition(a,b){ return a+b; }", @response.body
   end
 
@@ -86,7 +86,7 @@ class MimeControllerLayoutsTest < ActionController::TestCase
   end
 
   def test_non_navigational_format_with_no_template_fallbacks_to_html_template_with_no_layout
-    get :index, :format => :js
+    get :index, format: :js
     assert_equal "Hello Firefox", @response.body
   end
 end
diff --git a/actionpack/test/controller/mime/respond_to_test.rb b/actionpack/test/controller/mime/respond_to_test.rb
index 66d2fd7716..c025c7fa00 100644
--- a/actionpack/test/controller/mime/respond_to_test.rb
+++ b/actionpack/test/controller/mime/respond_to_test.rb
@@ -1,45 +1,53 @@
 require 'abstract_unit'
+require "active_support/log_subscriber/test_helper"
 
 class RespondToController < ActionController::Base
   layout :set_layout
 
+  before_action {
+    case params[:v]
+    when String then request.variant = params[:v].to_sym
+    when Array then request.variant = params[:v].map(&:to_sym)
+    end
+  }
+
   def html_xml_or_rss
     respond_to do |type|
-      type.html { render :text => "HTML"    }
-      type.xml  { render :text => "XML"     }
-      type.rss  { render :text => "RSS"     }
-      type.all  { render :text => "Nothing" }
+      type.html { render body: "HTML"    }
+      type.xml  { render body: "XML"     }
+      type.rss  { render body: "RSS"     }
+      type.all  { render body: "Nothing" }
     end
   end
 
   def js_or_html
     respond_to do |type|
-      type.html { render :text => "HTML"    }
-      type.js   { render :text => "JS"      }
-      type.all  { render :text => "Nothing" }
+      type.html { render body: "HTML"    }
+      type.js   { render body: "JS"      }
+      type.all  { render body: "Nothing" }
     end
   end
 
   def json_or_yaml
     respond_to do |type|
-      type.json { render :text => "JSON" }
-      type.yaml { render :text => "YAML" }
+      type.json { render body: "JSON" }
+      type.yaml { render body: "YAML" }
     end
   end
 
   def html_or_xml
     respond_to do |type|
-      type.html { render :text => "HTML"    }
-      type.xml  { render :text => "XML"     }
-      type.all  { render :text => "Nothing" }
+      type.html { render body: "HTML"    }
+      type.xml  { render body: "XML"     }
+      type.all  { render body: "Nothing" }
     end
   end
 
   def json_xml_or_html
     respond_to do |type|
-      type.json { render :text => 'JSON' }
+      type.json { render body: 'JSON' }
       type.xml { render :xml => 'XML' }
-      type.html { render :text => 'HTML' }
+      type.html { render body: 'HTML' }
     end
   end
 
@@ -48,14 +56,14 @@ class RespondToController < ActionController::Base
     request.format = :xml
 
     respond_to do |type|
-      type.html { render :text => "HTML"    }
-      type.xml  { render :text => "XML"     }
+      type.html { render body: "HTML"    }
+      type.xml  { render body: "XML"     }
     end
   end
 
   def just_xml
     respond_to do |type|
-      type.xml  { render :text => "XML" }
+      type.xml  { render body: "XML" }
     end
   end
 
@@ -73,52 +81,52 @@ class RespondToController < ActionController::Base
   def using_defaults_with_all
     respond_to do |type|
       type.html
-      type.all{ render text: "ALL" }
+      type.all { render body: "ALL" }
     end
   end
 
   def made_for_content_type
     respond_to do |type|
-      type.rss  { render :text => "RSS"  }
-      type.atom { render :text => "ATOM" }
-      type.all  { render :text => "Nothing" }
+      type.rss  { render body: "RSS"  }
+      type.atom { render body: "ATOM" }
+      type.all  { render body: "Nothing" }
     end
   end
 
   def custom_type_handling
     respond_to do |type|
-      type.html { render :text => "HTML"    }
-      type.custom("application/crazy-xml")  { render :text => "Crazy XML"  }
-      type.all  { render :text => "Nothing" }
+      type.html { render body: "HTML"    }
+      type.custom("application/crazy-xml")  { render body: "Crazy XML"  }
+      type.all  { render body: "Nothing" }
     end
   end
 
 
   def custom_constant_handling
     respond_to do |type|
-      type.html   { render :text => "HTML"   }
-      type.mobile { render :text => "Mobile" }
+      type.html   { render body: "HTML"   }
+      type.mobile { render body: "Mobile" }
     end
   end
 
   def custom_constant_handling_without_block
     respond_to do |type|
-      type.html   { render :text => "HTML"   }
+      type.html   { render body: "HTML"   }
       type.mobile
     end
   end
 
   def handle_any
     respond_to do |type|
-      type.html { render :text => "HTML" }
-      type.any(:js, :xml) { render :text => "Either JS or XML" }
+      type.html { render body: "HTML" }
+      type.any(:js, :xml) { render body: "Either JS or XML" }
     end
   end
 
   def handle_any_any
     respond_to do |type|
-      type.html { render :text => 'HTML' }
-      type.any { render :text => 'Whatever you ask for, I got it' }
+      type.html { render body: 'HTML' }
+      type.any { render body: 'Whatever you ask for, I got it' }
     end
   end
 
@@ -159,15 +167,15 @@ class RespondToController < ActionController::Base
     request.variant = :mobile
 
     respond_to do |type|
-      type.html { render text: "mobile" }
+      type.html { render body: "mobile" }
     end
   end
 
   def multiple_variants_for_format
     respond_to do |type|
       type.html do |html|
-        html.tablet { render text: "tablet" }
-        html.phone  { render text: "phone" }
+        html.tablet { render body: "tablet" }
+        html.phone  { render body: "phone" }
       end
     end
   end
@@ -175,7 +183,7 @@ class RespondToController < ActionController::Base
   def variant_plus_none_for_format
     respond_to do |format|
       format.html do |variant|
-        variant.phone { render text: "phone" }
+        variant.phone { render body: "phone" }
         variant.none
       end
     end
@@ -183,9 +191,9 @@ class RespondToController < ActionController::Base
 
   def variant_inline_syntax
     respond_to do |format|
-      format.js         { render text: "js"    }
-      format.html.none  { render text: "none"  }
-      format.html.phone { render text: "phone" }
+      format.js         { render body: "js"    }
+      format.html.none  { render body: "none"  }
+      format.html.phone { render body: "phone" }
     end
   end
 
@@ -200,8 +208,8 @@ class RespondToController < ActionController::Base
   def variant_any
     respond_to do |format|
       format.html do |variant|
-        variant.any(:tablet, :phablet){ render text: "any" }
-        variant.phone { render text: "phone" }
+        variant.any(:tablet, :phablet){ render body: "any" }
+        variant.phone { render body: "phone" }
       end
     end
   end
@@ -209,23 +217,23 @@ class RespondToController < ActionController::Base
   def variant_any_any
     respond_to do |format|
       format.html do |variant|
-        variant.any   { render text: "any"   }
-        variant.phone { render text: "phone" }
+        variant.any   { render body: "any"   }
+        variant.phone { render body: "phone" }
       end
     end
   end
 
   def variant_inline_any
     respond_to do |format|
-      format.html.any(:tablet, :phablet){ render text: "any" }
-      format.html.phone { render text: "phone" }
+      format.html.any(:tablet, :phablet){ render body: "any" }
+      format.html.phone { render body: "phone" }
     end
   end
 
   def variant_inline_any_any
     respond_to do |format|
-      format.html.phone { render text: "phone" }
-      format.html.any   { render text: "any"   }
+      format.html.phone { render body: "phone" }
+      format.html.any   { render body: "any"   }
     end
   end
 
@@ -238,16 +246,16 @@ class RespondToController < ActionController::Base
 
   def variant_any_with_none
     respond_to do |format|
-      format.html.any(:none, :phone){ render text: "none or phone" }
+      format.html.any(:none, :phone){ render body: "none or phone" }
     end
   end
 
   def format_any_variant_any
     respond_to do |format|
-      format.html { render text: "HTML" }
+      format.html { render body: "HTML" }
       format.any(:js, :xml) do |variant|
-        variant.phone{ render text: "phone" }
-        variant.any(:tablet, :phablet){ render text: "tablet" }
+        variant.phone{ render body: "phone" }
+        variant.any(:tablet, :phablet){ render body: "tablet" }
       end
     end
   end
@@ -310,17 +318,17 @@ class RespondToControllerTest < ActionController::TestCase
 
   def test_js_or_html
     @request.accept = "text/javascript, text/html"
-    xhr :get, :js_or_html
+    get :js_or_html, xhr: true
     assert_equal 'JS', @response.body
 
     @request.accept = "text/javascript, text/html"
-    xhr :get, :html_or_xml
+    get :html_or_xml, xhr: true
     assert_equal 'HTML', @response.body
 
     @request.accept = "text/javascript, text/html"
 
     assert_raises(ActionController::UnknownFormat) do
-      xhr :get, :just_xml
+      get :just_xml, xhr: true
     end
   end
 
@@ -335,13 +343,13 @@ class RespondToControllerTest < ActionController::TestCase
   end
 
   def test_json_or_yaml
-    xhr :get, :json_or_yaml
+    get :json_or_yaml, xhr: true
     assert_equal 'JSON', @response.body
 
-    get :json_or_yaml, :format => 'json'
+    get :json_or_yaml, format: 'json'
     assert_equal 'JSON', @response.body
 
-    get :json_or_yaml, :format => 'yaml'
+    get :json_or_yaml, format: 'yaml'
     assert_equal 'YAML', @response.body
 
     { 'YAML' => %w(text/yaml),
@@ -357,13 +365,13 @@ class RespondToControllerTest < ActionController::TestCase
 
   def test_js_or_anything
     @request.accept = "text/javascript, */*"
-    xhr :get, :js_or_html
+    get :js_or_html, xhr: true
     assert_equal 'JS', @response.body
 
-    xhr :get, :html_or_xml
+    get :html_or_xml, xhr: true
     assert_equal 'HTML', @response.body
 
-    xhr :get, :just_xml
+    get :just_xml, xhr: true
     assert_equal 'XML', @response.body
   end
 
@@ -408,14 +416,14 @@ class RespondToControllerTest < ActionController::TestCase
   def test_with_atom_content_type
     @request.accept = ""
     @request.env["CONTENT_TYPE"] = "application/atom+xml"
-    xhr :get, :made_for_content_type
+    get :made_for_content_type, xhr: true
     assert_equal "ATOM", @response.body
   end
 
   def test_with_rss_content_type
     @request.accept = ""
     @request.env["CONTENT_TYPE"] = "application/rss+xml"
-    xhr :get, :made_for_content_type
+    get :made_for_content_type, xhr: true
     assert_equal "RSS", @response.body
   end
 
@@ -474,7 +482,7 @@ class RespondToControllerTest < ActionController::TestCase
   end
 
   def test_handle_any_any_parameter_format
-    get :handle_any_any, {:format=>'html'}
+    get :handle_any_any, format: 'html'
     assert_equal 'HTML', @response.body
   end
 
@@ -497,7 +505,7 @@ class RespondToControllerTest < ActionController::TestCase
   end
 
   def test_handle_any_any_unkown_format
-    get :handle_any_any, { format: 'php' }
+    get :handle_any_any, format: 'php'
     assert_equal 'Whatever you ask for, I got it', @response.body
   end
 
@@ -525,18 +533,18 @@ class RespondToControllerTest < ActionController::TestCase
   end
 
   def test_xhr
-    xhr :get, :js_or_html
+    get :js_or_html, xhr: true
     assert_equal 'JS', @response.body
   end
 
   def test_custom_constant
-    get :custom_constant_handling, :format => "mobile"
+    get :custom_constant_handling, format: "mobile"
     assert_equal "text/x-mobile", @response.content_type
     assert_equal "Mobile", @response.body
   end
 
   def test_custom_constant_handling_without_block
-    get :custom_constant_handling_without_block, :format => "mobile"
+    get :custom_constant_handling_without_block, format: "mobile"
     assert_equal "text/x-mobile", @response.content_type
     assert_equal "Mobile", @response.body
   end
@@ -545,13 +553,13 @@ class RespondToControllerTest < ActionController::TestCase
     get :html_xml_or_rss
     assert_equal "HTML", @response.body
 
-    get :html_xml_or_rss, :format => "html"
+    get :html_xml_or_rss, format: "html"
     assert_equal "HTML", @response.body
 
-    get :html_xml_or_rss, :format => "xml"
+    get :html_xml_or_rss, format: "xml"
     assert_equal "XML", @response.body
 
-    get :html_xml_or_rss, :format => "rss"
+    get :html_xml_or_rss, format: "rss"
     assert_equal "RSS", @response.body
   end
 
@@ -559,12 +567,12 @@ class RespondToControllerTest < ActionController::TestCase
     get :forced_xml
     assert_equal "XML", @response.body
 
-    get :forced_xml, :format => "html"
+    get :forced_xml, format: "html"
     assert_equal "XML", @response.body
   end
 
   def test_extension_synonyms
-    get :html_xml_or_rss, :format => "xhtml"
+    get :html_xml_or_rss, format: "xhtml"
     assert_equal "HTML", @response.body
   end
 
@@ -581,7 +589,7 @@ class RespondToControllerTest < ActionController::TestCase
     get :using_defaults
     assert_equal "using_defaults - #{[:html]}", @response.body
 
-    get :using_defaults, :format => "xml"
+    get :using_defaults, format: "xml"
     assert_equal "using_defaults - #{[:xml]}", @response.body
   end
 
@@ -589,7 +597,7 @@ class RespondToControllerTest < ActionController::TestCase
     get :iphone_with_html_response_type
     assert_equal '<html><div id="html">Hello future from Firefox!</div></html>', @response.body
 
-    get :iphone_with_html_response_type, :format => "iphone"
+    get :iphone_with_html_response_type, format: "iphone"
     assert_equal "text/html", @response.content_type
     assert_equal '<html><div id="iphone">Hello iPhone future from iPhone!</div></html>', @response.body
   end
@@ -603,40 +611,45 @@ class RespondToControllerTest < ActionController::TestCase
 
   def test_invalid_format
     assert_raises(ActionController::UnknownFormat) do
-      get :using_defaults, :format => "invalidformat"
+      get :using_defaults, format: "invalidformat"
     end
   end
 
   def test_invalid_variant
-    @request.variant = :invalid
-    assert_raises(ActionView::MissingTemplate) do
-      get :variant_with_implicit_rendering
-    end
+    logger = ActiveSupport::LogSubscriber::TestHelper::MockLogger.new
+    old_logger, ActionController::Base.logger = ActionController::Base.logger, logger
+
+    get :variant_with_implicit_rendering, params: { v: :invalid }
+    assert_response :no_content
+    assert_equal 1, logger.logged(:info).select{ |s| s =~ /No template found/ }.size, "Implicit head :no_content not logged"
+  ensure
+    ActionController::Base.logger = old_logger
   end
 
   def test_variant_not_set_regular_template_missing
-    assert_raises(ActionView::MissingTemplate) do
-      get :variant_with_implicit_rendering
-    end
+    get :variant_with_implicit_rendering
+    assert_response :no_content
   end
 
   def test_variant_with_implicit_rendering
-    @request.variant = :mobile
-    get :variant_with_implicit_rendering
+    get :variant_with_implicit_rendering, params: { v: :implicit }
+    assert_response :no_content
+  end
+
+  def test_variant_with_implicit_template_rendering
+    get :variant_with_implicit_rendering, params: { v: :mobile }
     assert_equal "text/html", @response.content_type
     assert_equal "mobile", @response.body
   end
 
   def test_variant_with_format_and_custom_render
-    @request.variant = :phone
-    get :variant_with_format_and_custom_render
+    get :variant_with_format_and_custom_render, params: { v: :phone }
     assert_equal "text/html", @response.content_type
     assert_equal "mobile", @response.body
   end
 
   def test_multiple_variants_for_format
-    @request.variant = :tablet
-    get :multiple_variants_for_format
+    get :multiple_variants_for_format, params: { v: :tablet }
     assert_equal "text/html", @response.content_type
     assert_equal "tablet", @response.body
   end
@@ -656,32 +669,27 @@ class RespondToControllerTest < ActionController::TestCase
     assert_equal "text/html", @response.content_type
     assert_equal "none", @response.body
 
-    @request.variant = :phone
-    get :variant_inline_syntax
+    get :variant_inline_syntax, params: { v: :phone }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
   end
 
   def test_variant_inline_syntax_without_block
-    @request.variant = :phone
-    get :variant_inline_syntax_without_block
+    get :variant_inline_syntax_without_block, params: { v: :phone }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
   end
 
   def test_variant_any
-    @request.variant = :phone
-    get :variant_any
+    get :variant_any, params: { v: :phone }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
 
-    @request.variant = :tablet
-    get :variant_any
+    get :variant_any, params: { v: :tablet }
     assert_equal "text/html", @response.content_type
     assert_equal "any", @response.body
 
-    @request.variant = :phablet
-    get :variant_any
+    get :variant_any, params: { v: :phablet }
     assert_equal "text/html", @response.content_type
     assert_equal "any", @response.body
   end
@@ -691,54 +699,45 @@ class RespondToControllerTest < ActionController::TestCase
     assert_equal "text/html", @response.content_type
     assert_equal "any", @response.body
 
-    @request.variant = :phone
-    get :variant_any_any
+    get :variant_any_any, params: { v: :phone }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
 
-    @request.variant = :yolo
-    get :variant_any_any
+    get :variant_any_any, params: { v: :yolo }
     assert_equal "text/html", @response.content_type
     assert_equal "any", @response.body
   end
 
   def test_variant_inline_any
-    @request.variant = :phone
-    get :variant_any
+    get :variant_any, params: { v: :phone }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
 
-    @request.variant = :tablet
-    get :variant_inline_any
+    get :variant_inline_any, params: { v: :tablet }
     assert_equal "text/html", @response.content_type
     assert_equal "any", @response.body
 
-    @request.variant = :phablet
-    get :variant_inline_any
+    get :variant_inline_any, params: { v: :phablet }
     assert_equal "text/html", @response.content_type
     assert_equal "any", @response.body
   end
 
   def test_variant_inline_any_any
-    @request.variant = :phone
-    get :variant_inline_any_any
+    get :variant_inline_any_any, params: { v: :phone }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
 
-    @request.variant = :yolo
-    get :variant_inline_any_any
+    get :variant_inline_any_any, params: { v: :yolo }
     assert_equal "text/html", @response.content_type
     assert_equal "any", @response.body
   end
 
   def test_variant_any_implicit_render
-    @request.variant = :tablet
-    get :variant_any_implicit_render
+    get :variant_any_implicit_render, params: { v: :tablet }
     assert_equal "text/html", @response.content_type
     assert_equal "tablet", @response.body
 
-    @request.variant = :phablet
-    get :variant_any_implicit_render
+    get :variant_any_implicit_render, params: { v: :phablet }
     assert_equal "text/html", @response.content_type
     assert_equal "phablet", @response.body
   end
@@ -748,37 +747,53 @@ class RespondToControllerTest < ActionController::TestCase
     assert_equal "text/html", @response.content_type
     assert_equal "none or phone", @response.body
 
-    @request.variant = :phone
-    get :variant_any_with_none
+    get :variant_any_with_none, params: { v: :phone }
     assert_equal "text/html", @response.content_type
     assert_equal "none or phone", @response.body
   end
 
   def test_format_any_variant_any
-    @request.variant = :tablet
-    get :format_any_variant_any, format: :js
+    get :format_any_variant_any, format: :js, params: { v: :tablet }
     assert_equal "text/javascript", @response.content_type
     assert_equal "tablet", @response.body
   end
 
   def test_variant_negotiation_inline_syntax
-    @request.variant = [:tablet, :phone]
-    get :variant_inline_syntax_without_block
+    get :variant_inline_syntax_without_block, params: { v: [:tablet, :phone] }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
   end
 
   def test_variant_negotiation_block_syntax
-    @request.variant = [:tablet, :phone]
-    get :variant_plus_none_for_format
+    get :variant_plus_none_for_format, params: { v: [:tablet, :phone] }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
   end
 
   def test_variant_negotiation_without_block
-    @request.variant = [:tablet, :phone]
-    get :variant_inline_syntax_without_block
+    get :variant_inline_syntax_without_block, params: { v: [:tablet, :phone] }
     assert_equal "text/html", @response.content_type
     assert_equal "phone", @response.body
   end
 end
+
+class RespondToWithBlockOnDefaultRenderController < ActionController::Base
+  def show
+    default_render do
+      render body: 'default_render yielded'
+    end
+  end
+end
+
+class RespondToWithBlockOnDefaultRenderControllerTest < ActionController::TestCase
+  def setup
+    super
+    @request.host = "www.example.com"
+  end
+
+  def test_default_render_uses_block_when_no_template_exists
+    get :show
+    assert_equal "default_render yielded", @response.body
+    assert_equal "text/plain", @response.content_type
+  end
+end
diff --git a/actionpack/test/controller/new_base/bare_metal_test.rb b/actionpack/test/controller/new_base/bare_metal_test.rb
index 246ba099af..e61f4d241b 100644
--- a/actionpack/test/controller/new_base/bare_metal_test.rb
+++ b/actionpack/test/controller/new_base/bare_metal_test.rb
@@ -2,8 +2,6 @@ require "abstract_unit"
 
 module BareMetalTest
   class BareController < ActionController::Metal
-    include ActionController::RackDelegation
-
     def index
       self.response_body = "Hello world"
     end
@@ -28,9 +26,18 @@ module BareMetalTest
 
     test "response_body value is wrapped in an array when the value is a String" do
       controller = BareController.new
+      controller.set_request!(ActionDispatch::Request.new({}))
+      controller.set_response!(BareController.make_response!(controller.request))
       controller.index
       assert_equal ["Hello world"], controller.response_body
     end
+
+    test "connect a request to controller instance without dispatch" do
+      env = {}
+      controller = BareController.new
+      controller.set_request! ActionDispatch::Request.new(env)
+      assert controller.request
+    end
   end
 
   class HeadController < ActionController::Metal
@@ -114,34 +121,40 @@ module BareMetalTest
     end
 
     test "head :no_content (204) does not return any content" do
-      content = HeadController.action(:no_content).call(Rack::MockRequest.env_for("/")).third.first
+      content = body(HeadController.action(:no_content).call(Rack::MockRequest.env_for("/")))
       assert_empty content
     end
 
     test "head :reset_content (205) does not return any content" do
-      content = HeadController.action(:reset_content).call(Rack::MockRequest.env_for("/")).third.first
+      content = body(HeadController.action(:reset_content).call(Rack::MockRequest.env_for("/")))
       assert_empty content
     end
 
     test "head :not_modified (304) does not return any content" do
-      content = HeadController.action(:not_modified).call(Rack::MockRequest.env_for("/")).third.first
+      content = body(HeadController.action(:not_modified).call(Rack::MockRequest.env_for("/")))
       assert_empty content
     end
 
     test "head :continue (100) does not return any content" do
-      content = HeadController.action(:continue).call(Rack::MockRequest.env_for("/")).third.first
+      content = body(HeadController.action(:continue).call(Rack::MockRequest.env_for("/")))
       assert_empty content
     end
 
     test "head :switching_protocols (101) does not return any content" do
-      content = HeadController.action(:switching_protocols).call(Rack::MockRequest.env_for("/")).third.first
+      content = body(HeadController.action(:switching_protocols).call(Rack::MockRequest.env_for("/")))
       assert_empty content
     end
 
     test "head :processing (102) does not return any content" do
-      content = HeadController.action(:processing).call(Rack::MockRequest.env_for("/")).third.first
+      content = body(HeadController.action(:processing).call(Rack::MockRequest.env_for("/")))
       assert_empty content
     end
+
+    def body(rack_response)
+      buf = []
+      rack_response[2].each { |x| buf << x }
+      buf.join
+    end
   end
 
   class BareControllerTest < ActionController::TestCase
diff --git a/actionpack/test/controller/new_base/base_test.rb b/actionpack/test/controller/new_base/base_test.rb
index 964f22eb03..0755dafe93 100644
--- a/actionpack/test/controller/new_base/base_test.rb
+++ b/actionpack/test/controller/new_base/base_test.rb
@@ -6,7 +6,7 @@ module Dispatching
     before_action :authenticate
 
     def index
-      render :text => "success"
+      render body: "success"
     end
 
     def modify_response_body
@@ -22,7 +22,7 @@ module Dispatching
     end
 
     def show_actions
-      render :text => "actions: #{action_methods.to_a.sort.join(', ')}"
+      render body: "actions: #{action_methods.to_a.sort.join(', ')}"
     end
 
     protected
@@ -51,7 +51,7 @@ module Dispatching
 
       assert_body "success"
       assert_status 200
-      assert_content_type "text/html; charset=utf-8"
+      assert_content_type "text/plain; charset=utf-8"
     end
 
     # :api: plugin
diff --git a/actionpack/test/controller/new_base/content_negotiation_test.rb b/actionpack/test/controller/new_base/content_negotiation_test.rb
index 5fd5946619..c0e92b3b05 100644
--- a/actionpack/test/controller/new_base/content_negotiation_test.rb
+++ b/actionpack/test/controller/new_base/content_negotiation_test.rb
@@ -9,18 +9,18 @@ module ContentNegotiation
     )]
 
     def all
-      render :text => self.formats.inspect
+      render plain: self.formats.inspect
     end
   end
 
   class TestContentNegotiation < Rack::TestCase
     test "A */* Accept header will return HTML" do
-      get "/content_negotiation/basic/hello", {}, "HTTP_ACCEPT" => "*/*"
+      get "/content_negotiation/basic/hello", headers: { "HTTP_ACCEPT" => "*/*" }
       assert_body "Hello world */*!"
     end
 
     test "Not all mimes are converted to symbol" do
-      get "/content_negotiation/basic/all", {}, "HTTP_ACCEPT" => "text/plain, mime/another"
+      get "/content_negotiation/basic/all", headers: { "HTTP_ACCEPT" => "text/plain, mime/another" }
       assert_body '[:text, "mime/another"]'
     end
   end
diff --git a/actionpack/test/controller/new_base/content_type_test.rb b/actionpack/test/controller/new_base/content_type_test.rb
index 9b57641e75..a9dcdde4b8 100644
--- a/actionpack/test/controller/new_base/content_type_test.rb
+++ b/actionpack/test/controller/new_base/content_type_test.rb
@@ -3,16 +3,16 @@ require 'abstract_unit'
 module ContentType
   class BaseController < ActionController::Base
     def index
-      render :text => "Hello world!"
+      render body: "Hello world!"
     end
 
     def set_on_response_obj
-      response.content_type = Mime::RSS
-      render :text => "Hello world!"
+      response.content_type = Mime[:rss]
+      render body: "Hello world!"
     end
 
     def set_on_render
-      render :text => "Hello world!", :content_type => Mime::RSS
+      render body: "Hello world!", content_type: Mime[:rss]
     end
   end
 
@@ -30,17 +30,17 @@ module ContentType
   class CharsetController < ActionController::Base
     def set_on_response_obj
       response.charset = "utf-16"
-      render :text => "Hello world!"
+      render body: "Hello world!"
     end
 
     def set_as_nil_on_response_obj
       response.charset = nil
-      render :text => "Hello world!"
+      render body: "Hello world!"
     end
   end
 
   class ExplicitContentTypeTest < Rack::TestCase
-    test "default response is HTML and UTF8" do
+    test "default response is text/plain and UTF8" do
       with_routing do |set|
         set.draw do
           get ':controller', :action => 'index'
@@ -49,7 +49,7 @@ module ContentType
         get "/content_type/base"
 
         assert_body "Hello world!"
-        assert_header "Content-Type", "text/html; charset=utf-8"
+        assert_header "Content-Type", "text/plain; charset=utf-8"
       end
     end
 
@@ -76,7 +76,7 @@ module ContentType
     end
 
     test "sets Content-Type as application/xml when rendering *.xml.erb" do
-      get "/content_type/implied/i_am_xml_erb", "format" => "xml"
+      get "/content_type/implied/i_am_xml_erb", params: { "format" => "xml" }
 
       assert_header "Content-Type", "application/xml; charset=utf-8"
     end
@@ -88,7 +88,7 @@ module ContentType
     end
 
     test "sets Content-Type as application/xml when rendering *.xml.builder" do
-      get "/content_type/implied/i_am_xml_builder", "format" => "xml"
+      get "/content_type/implied/i_am_xml_builder", params: { "format" => "xml" }
 
       assert_header "Content-Type", "application/xml; charset=utf-8"
     end
@@ -99,14 +99,14 @@ module ContentType
       get "/content_type/charset/set_on_response_obj"
 
       assert_body   "Hello world!"
-      assert_header "Content-Type", "text/html; charset=utf-16"
+      assert_header "Content-Type", "text/plain; charset=utf-16"
     end
 
     test "setting the charset of the response as nil directly on the response object" do
       get "/content_type/charset/set_as_nil_on_response_obj"
 
       assert_body   "Hello world!"
-      assert_header "Content-Type", "text/html; charset=utf-8"
+      assert_header "Content-Type", "text/plain; charset=utf-8"
     end
   end
 end
diff --git a/actionpack/test/controller/new_base/metal_test.rb b/actionpack/test/controller/new_base/metal_test.rb
deleted file mode 100644
index 45a6619eb4..0000000000
--- a/actionpack/test/controller/new_base/metal_test.rb
+++ /dev/null
@@ -1,45 +0,0 @@
-require 'abstract_unit'
-
-module MetalTest
-  class MetalMiddleware < ActionController::Middleware
-    def call(env)
-      if env["PATH_INFO"] =~ /authed/
-        app.call(env)
-      else
-        [401, headers, "Not authed!"]
-      end
-    end
-  end
-
-  class Endpoint
-    def call(env)
-      [200, {}, "Hello World"]
-    end
-  end
-
-  class TestMiddleware < ActiveSupport::TestCase
-    include RackTestUtils
-
-    def setup
-      @app = Rack::Builder.new do
-        use MetalTest::MetalMiddleware
-        run MetalTest::Endpoint.new
-      end.to_app
-    end
-
-    test "it can call the next app by using @app" do
-      env = Rack::MockRequest.env_for("/authed")
-      response = @app.call(env)
-
-      assert_equal "Hello World", body_to_string(response[2])
-    end
-
-    test "it can return a response using the normal AC::Metal techniques" do
-      env = Rack::MockRequest.env_for("/")
-      response = @app.call(env)
-
-      assert_equal "Not authed!", body_to_string(response[2])
-      assert_equal 401, response[0]
-    end
-  end
-end
diff --git a/actionpack/test/controller/new_base/middleware_test.rb b/actionpack/test/controller/new_base/middleware_test.rb
index 6b7b5e10e3..85a1f351f0 100644
--- a/actionpack/test/controller/new_base/middleware_test.rb
+++ b/actionpack/test/controller/new_base/middleware_test.rb
@@ -75,7 +75,7 @@ module MiddlewareTest
 
     test "middleware that is 'use'd is called as part of the Rack application" do
       result = @app.call(env_for("/"))
-      assert_equal "Hello World", RackTestUtils.body_to_string(result[2])
+      assert_equal ["Hello World"], [].tap { |a| result[2].each { |x| a << x } }
       assert_equal "Success", result[1]["Middleware-Test"]
     end
 
diff --git a/actionpack/test/controller/new_base/render_action_test.rb b/actionpack/test/controller/new_base/render_action_test.rb
index 475bf9d3c9..3bf1dd0ede 100644
--- a/actionpack/test/controller/new_base/render_action_test.rb
+++ b/actionpack/test/controller/new_base/render_action_test.rb
@@ -88,7 +88,7 @@ module RenderAction
 
     test "rendering with layout => true" do
       assert_raise(ArgumentError) do
-        get "/render_action/basic/hello_world_with_layout", {}, "action_dispatch.show_exceptions" => false
+        get "/render_action/basic/hello_world_with_layout", headers: { "action_dispatch.show_exceptions" => false }
       end
     end
 
@@ -108,7 +108,7 @@ module RenderAction
 
     test "rendering with layout => 'greetings'" do
       assert_raise(ActionView::MissingTemplate) do
-        get "/render_action/basic/hello_world_with_custom_layout", {}, "action_dispatch.show_exceptions" => false
+        get "/render_action/basic/hello_world_with_custom_layout", headers: { "action_dispatch.show_exceptions" => false }
       end
     end
   end
diff --git a/actionpack/test/controller/new_base/render_html_test.rb b/actionpack/test/controller/new_base/render_html_test.rb
index fe11501eeb..e9ea57e329 100644
--- a/actionpack/test/controller/new_base/render_html_test.rb
+++ b/actionpack/test/controller/new_base/render_html_test.rb
@@ -179,7 +179,7 @@ module RenderHtml
 
     test "rendering from minimal controller returns response with text/html content type" do
       get "/render_html/minimal/index"
-      assert_content_type "text/html"
+      assert_content_type "text/html; charset=utf-8"
     end
 
     test "rendering from normal controller returns response with text/html content type" do
diff --git a/actionpack/test/controller/new_base/render_layout_test.rb b/actionpack/test/controller/new_base/render_layout_test.rb
index 4ac40ca405..7ab3777026 100644
--- a/actionpack/test/controller/new_base/render_layout_test.rb
+++ b/actionpack/test/controller/new_base/render_layout_test.rb
@@ -86,7 +86,7 @@ module ControllerLayouts
     XML_INSTRUCT = %Q(<?xml version="1.0" encoding="UTF-8"?>\n)
 
     test "if XML is selected, an HTML template is not also selected" do
-      get :index, :format => "xml"
+      get :index, params: { format: "xml" }
       assert_response XML_INSTRUCT
     end
 
@@ -96,7 +96,7 @@ module ControllerLayouts
     end
 
     test "a layout for JS is ignored even if explicitly provided for HTML" do
-      get :explicit, { :format => "js" }
+      get :explicit, params: { format: "js" }
       assert_response "alert('foo');"
     end
   end
@@ -120,7 +120,7 @@ module ControllerLayouts
     testing ControllerLayouts::FalseLayoutMethodController
 
     test "access false layout returned by a method/proc" do
-      get :index, :format => "js"
+      get :index, params: { format: "js" }
       assert_response "alert('foo');"
     end
   end
diff --git a/actionpack/test/controller/new_base/render_plain_test.rb b/actionpack/test/controller/new_base/render_plain_test.rb
index 0e36d36b50..0881442bd0 100644
--- a/actionpack/test/controller/new_base/render_plain_test.rb
+++ b/actionpack/test/controller/new_base/render_plain_test.rb
@@ -157,7 +157,7 @@ module RenderPlain
 
     test "rendering from minimal controller returns response with text/plain content type" do
       get "/render_plain/minimal/index"
-      assert_content_type "text/plain"
+      assert_content_type "text/plain; charset=utf-8"
     end
 
     test "rendering from normal controller returns response with text/plain content type" do
diff --git a/actionpack/test/controller/new_base/render_streaming_test.rb b/actionpack/test/controller/new_base/render_streaming_test.rb
index 4c9126ca8c..9ea056194a 100644
--- a/actionpack/test/controller/new_base/render_streaming_test.rb
+++ b/actionpack/test/controller/new_base/render_streaming_test.rb
@@ -97,7 +97,7 @@ module RenderStreaming
     end
 
     test "do not stream on HTTP/1.0" do
-      get "/render_streaming/basic/hello_world", nil, "HTTP_VERSION" => "HTTP/1.0"
+      get "/render_streaming/basic/hello_world", headers: { "HTTP_VERSION" => "HTTP/1.0" }
       assert_body "Hello world, I'm here!"
       assert_status 200
       assert_equal "22", headers["Content-Length"]
diff --git a/actionpack/test/controller/new_base/render_template_test.rb b/actionpack/test/controller/new_base/render_template_test.rb
index 42a86b1d0d..b06ce5db40 100644
--- a/actionpack/test/controller/new_base/render_template_test.rb
+++ b/actionpack/test/controller/new_base/render_template_test.rb
@@ -111,7 +111,7 @@ module RenderTemplate
     end
 
     test "rendering a builder template" do
-      get :builder_template, "format" => "xml"
+      get :builder_template, params: { "format" => "xml" }
       assert_response "<html>\n  <p>Hello</p>\n</html>\n"
     end
 
@@ -126,7 +126,7 @@ module RenderTemplate
       assert_body "Hello <strong>this is also raw</strong> in an html template"
       assert_status 200
 
-      get :with_implicit_raw, format: 'text'
+      get :with_implicit_raw, params: { format: 'text' }
 
       assert_body "Hello <strong>this is also raw</strong> in a text template"
       assert_status 200
@@ -186,21 +186,21 @@ module RenderTemplate
       end
     end
 
-    test "rendering with layout => :true" do
+    test "rendering with layout => true" do
       get "/render_template/with_layout/with_layout"
 
       assert_body "Hello from basic.html.erb, I'm here!"
       assert_status 200
     end
 
-    test "rendering with layout => :false" do
+    test "rendering with layout => false" do
       get "/render_template/with_layout/with_layout_false"
 
       assert_body "Hello from basic.html.erb"
       assert_status 200
     end
 
-    test "rendering with layout => :nil" do
+    test "rendering with layout => nil" do
       get "/render_template/with_layout/with_layout_nil"
 
       assert_body "Hello from basic.html.erb"
diff --git a/actionpack/test/controller/new_base/render_test.rb b/actionpack/test/controller/new_base/render_test.rb
index 5635e16234..963f2c2f5c 100644
--- a/actionpack/test/controller/new_base/render_test.rb
+++ b/actionpack/test/controller/new_base/render_test.rb
@@ -37,14 +37,14 @@ module Render
     private
 
     def secretz
-      render :text => "FAIL WHALE!"
+      render plain: "FAIL WHALE!"
     end
   end
 
   class DoubleRenderController < ActionController::Base
     def index
-      render :text => "hello"
-      render :text => "world"
+      render plain: "hello"
+      render plain: "world"
     end
   end
 
@@ -74,7 +74,7 @@ module Render
         end
 
         assert_raises(AbstractController::DoubleRenderError) do
-          get "/render/double_render", {}, "action_dispatch.show_exceptions" => false
+          get "/render/double_render", headers: { "action_dispatch.show_exceptions" => false }
         end
       end
     end
@@ -84,13 +84,13 @@ module Render
     # Only public methods on actual controllers are callable actions
     test "raises an exception when a method of Object is called" do
       assert_raises(AbstractController::ActionNotFound) do
-        get "/render/blank_render/clone", {}, "action_dispatch.show_exceptions" => false
+        get "/render/blank_render/clone", headers: { "action_dispatch.show_exceptions" => false }
       end
     end
 
     test "raises an exception when a private method is called" do
       assert_raises(AbstractController::ActionNotFound) do
-        get "/render/blank_render/secretz", {}, "action_dispatch.show_exceptions" => false
+        get "/render/blank_render/secretz", headers: { "action_dispatch.show_exceptions" => false }
       end
     end
   end
diff --git a/actionpack/test/controller/new_base/render_text_test.rb b/actionpack/test/controller/new_base/render_text_test.rb
index 10bad57cd6..048458178c 100644
--- a/actionpack/test/controller/new_base/render_text_test.rb
+++ b/actionpack/test/controller/new_base/render_text_test.rb
@@ -73,7 +73,10 @@ module RenderText
 
   class RenderTextTest < Rack::TestCase
     test "rendering text from a minimal controller" do
-      get "/render_text/minimal/index"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/minimal/index"
+      end
+
       assert_body "Hello World!"
       assert_status 200
     end
@@ -82,7 +85,10 @@ module RenderText
       with_routing do |set|
         set.draw { get ':controller', action: 'index' }
 
-        get "/render_text/simple"
+        ActiveSupport::Deprecation.silence do
+          get "/render_text/simple"
+        end
+
         assert_body "hello david"
         assert_status 200
       end
@@ -92,7 +98,9 @@ module RenderText
       with_routing do |set|
         set.draw { get ':controller', action: 'index' }
 
-        get "/render_text/with_layout"
+        ActiveSupport::Deprecation.silence do
+          get "/render_text/with_layout"
+        end
 
         assert_body "hello david"
         assert_status 200
@@ -100,59 +108,81 @@ module RenderText
     end
 
     test "rendering text, while also providing a custom status code" do
-      get "/render_text/with_layout/custom_code"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/with_layout/custom_code"
+      end
 
       assert_body "hello world"
       assert_status 404
     end
 
     test "rendering text with nil returns an empty body" do
-      get "/render_text/with_layout/with_nil"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/with_layout/with_nil"
+      end
 
       assert_body ""
       assert_status 200
     end
 
     test "Rendering text with nil and custom status code returns an empty body and the status" do
-      get "/render_text/with_layout/with_nil_and_status"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/with_layout/with_nil_and_status"
+      end
 
       assert_body ""
       assert_status 403
     end
 
     test "rendering text with false returns the string 'false'" do
-      get "/render_text/with_layout/with_false"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/with_layout/with_false"
+      end
 
       assert_body "false"
       assert_status 200
     end
 
     test "rendering text with layout: true" do
-      get "/render_text/with_layout/with_layout_true"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/with_layout/with_layout_true"
+      end
 
       assert_body "hello world, I'm here!"
       assert_status 200
     end
 
     test "rendering text with layout: 'greetings'" do
-      get "/render_text/with_layout/with_custom_layout"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/with_layout/with_custom_layout"
+      end
 
       assert_body "hello world, I wish thee well."
       assert_status 200
     end
 
     test "rendering text with layout: false" do
-      get "/render_text/with_layout/with_layout_false"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/with_layout/with_layout_false"
+      end
 
       assert_body "hello world"
       assert_status 200
     end
 
     test "rendering text with layout: nil" do
-      get "/render_text/with_layout/with_layout_nil"
+      ActiveSupport::Deprecation.silence do
+        get "/render_text/with_layout/with_layout_nil"
+      end
 
       assert_body "hello world"
       assert_status 200
     end
+
+    test "rendering text displays deprecation warning" do
+      assert_deprecated do
+        get "/render_text/with_layout/with_layout_nil"
+      end
+    end
   end
 end
diff --git a/actionpack/test/controller/parameters/always_permitted_parameters_test.rb b/actionpack/test/controller/parameters/always_permitted_parameters_test.rb
index 059f310d49..efaf8a96c3 100644
--- a/actionpack/test/controller/parameters/always_permitted_parameters_test.rb
+++ b/actionpack/test/controller/parameters/always_permitted_parameters_test.rb
@@ -14,7 +14,13 @@ class AlwaysPermittedParametersTest < ActiveSupport::TestCase
 
   test "shows deprecations warning on NEVER_UNPERMITTED_PARAMS" do
     assert_deprecated do
-       ActionController::Parameters::NEVER_UNPERMITTED_PARAMS
+      ActionController::Parameters::NEVER_UNPERMITTED_PARAMS
+    end
+  end
+
+  test "returns super on missing constant other than NEVER_UNPERMITTED_PARAMS" do
+    ActionController::Parameters.superclass.stub :const_missing, "super" do
+      assert_equal "super", ActionController::Parameters::NON_EXISTING_CONSTANT
     end
   end
 
diff --git a/actionpack/test/controller/parameters/nested_parameters_test.rb b/actionpack/test/controller/parameters/nested_parameters_test.rb
index 3b1257e8d5..7151a8567c 100644
--- a/actionpack/test/controller/parameters/nested_parameters_test.rb
+++ b/actionpack/test/controller/parameters/nested_parameters_test.rb
@@ -136,7 +136,7 @@ class NestedParametersTest < ActiveSupport::TestCase
         authors_attributes: {
           :'0' => { name: 'William Shakespeare', age_of_death: '52' },
           :'1' => { name: 'Unattributed Assistant' },
-          :'2' => { name: %w(injected names)}
+          :'2' => { name: %w(injected names) }
         }
       }
     })
diff --git a/actionpack/test/controller/parameters/parameters_permit_test.rb b/actionpack/test/controller/parameters/parameters_permit_test.rb
index 2ed486516d..9f7d14e85d 100644
--- a/actionpack/test/controller/parameters/parameters_permit_test.rb
+++ b/actionpack/test/controller/parameters/parameters_permit_test.rb
@@ -194,6 +194,19 @@ class ParametersPermitTest < ActiveSupport::TestCase
     assert_equal "monkey", @params.fetch(:foo) { "monkey" }
   end
 
+  test "fetch doesnt raise ParameterMissing exception if there is a default that is nil" do
+    assert_equal nil, @params.fetch(:foo, nil)
+    assert_equal nil, @params.fetch(:foo) { nil }
+  end
+
+  test 'KeyError in fetch block should not be covered up' do
+    params = ActionController::Parameters.new
+    e = assert_raises(KeyError) do
+      params.fetch(:missing_key) { {}.fetch(:also_missing) }
+    end
+    assert_match(/:also_missing$/, e.message)
+  end
+
   test "not permitted is sticky beyond merges" do
     assert !@params.merge(a: "b").permitted?
   end
@@ -253,7 +266,6 @@ class ParametersPermitTest < ActiveSupport::TestCase
 
     assert @params.to_h.is_a? Hash
     assert_not @params.to_h.is_a? ActionController::Parameters
-    assert_equal @params.to_hash, @params.to_h
   end
 
   test "to_h returns converted hash when .permit_all_parameters is set" do
@@ -284,6 +296,5 @@ class ParametersPermitTest < ActiveSupport::TestCase
   test "to_unsafe_h returns unfiltered params" do
     assert @params.to_h.is_a? Hash
     assert_not @params.to_h.is_a? ActionController::Parameters
-    assert_equal @params.to_hash, @params.to_unsafe_h
   end
 end
diff --git a/actionpack/test/controller/params_wrapper_test.rb b/actionpack/test/controller/params_wrapper_test.rb
index 645ecae220..7226beed26 100644
--- a/actionpack/test/controller/params_wrapper_test.rb
+++ b/actionpack/test/controller/params_wrapper_test.rb
@@ -28,8 +28,17 @@ class ParamsWrapperTest < ActionController::TestCase
     end
   end
 
-  class User; end
-  class Person; end
+  class User
+    def self.attribute_names
+      []
+    end
+  end
+
+  class Person
+    def self.attribute_names
+      []
+    end
+  end
 
   tests UsersController
 
@@ -40,7 +49,7 @@ class ParamsWrapperTest < ActionController::TestCase
   def test_filtered_parameters
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu' }
+      post :parse, params: { 'username' => 'sikachu' }
       assert_equal @request.filtered_parameters, { 'controller' => 'params_wrapper_test/users', 'action' => 'parse', 'username' => 'sikachu', 'user' => { 'username' => 'sikachu' } }
     end
   end
@@ -48,7 +57,7 @@ class ParamsWrapperTest < ActionController::TestCase
   def test_derived_name_from_controller
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu' }
+      post :parse, params: { 'username' => 'sikachu' }
       assert_parameters({ 'username' => 'sikachu', 'user' => { 'username' => 'sikachu' }})
     end
   end
@@ -58,7 +67,7 @@ class ParamsWrapperTest < ActionController::TestCase
       UsersController.wrap_parameters :person
 
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu' }
+      post :parse, params: { 'username' => 'sikachu' }
       assert_parameters({ 'username' => 'sikachu', 'person' => { 'username' => 'sikachu' }})
     end
   end
@@ -68,7 +77,7 @@ class ParamsWrapperTest < ActionController::TestCase
       UsersController.wrap_parameters Person
 
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu' }
+      post :parse, params: { 'username' => 'sikachu' }
       assert_parameters({ 'username' => 'sikachu', 'person' => { 'username' => 'sikachu' }})
     end
   end
@@ -78,7 +87,7 @@ class ParamsWrapperTest < ActionController::TestCase
       UsersController.wrap_parameters :include => :username
 
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+      post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
       assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'username' => 'sikachu' }})
     end
   end
@@ -88,7 +97,7 @@ class ParamsWrapperTest < ActionController::TestCase
       UsersController.wrap_parameters :exclude => :title
 
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+      post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
       assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'username' => 'sikachu' }})
     end
   end
@@ -98,7 +107,7 @@ class ParamsWrapperTest < ActionController::TestCase
       UsersController.wrap_parameters :person, :include => :username
 
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+      post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
       assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'person' => { 'username' => 'sikachu' }})
     end
   end
@@ -106,7 +115,7 @@ class ParamsWrapperTest < ActionController::TestCase
   def test_not_enabled_format
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/xml'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+      post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
       assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer' })
     end
   end
@@ -115,7 +124,7 @@ class ParamsWrapperTest < ActionController::TestCase
     with_default_wrapper_options do
       UsersController.wrap_parameters false
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+      post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
       assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer' })
     end
   end
@@ -125,7 +134,7 @@ class ParamsWrapperTest < ActionController::TestCase
       UsersController.wrap_parameters :format => :xml
 
       @request.env['CONTENT_TYPE'] = 'application/xml'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+      post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
       assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'username' => 'sikachu', 'title' => 'Developer' }})
     end
   end
@@ -133,7 +142,7 @@ class ParamsWrapperTest < ActionController::TestCase
   def test_not_wrap_reserved_parameters
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'authenticity_token' => 'pwned', '_method' => 'put', 'utf8' => '&#9731;', 'username' => 'sikachu' }
+      post :parse, params: { 'authenticity_token' => 'pwned', '_method' => 'put', 'utf8' => '&#9731;', 'username' => 'sikachu' }
       assert_parameters({ 'authenticity_token' => 'pwned', '_method' => 'put', 'utf8' => '&#9731;', 'username' => 'sikachu', 'user' => { 'username' => 'sikachu' }})
     end
   end
@@ -141,7 +150,7 @@ class ParamsWrapperTest < ActionController::TestCase
   def test_no_double_wrap_if_key_exists
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'user' => { 'username' => 'sikachu' }}
+      post :parse, params: { 'user' => { 'username' => 'sikachu' }}
       assert_parameters({ 'user' => { 'username' => 'sikachu' }})
     end
   end
@@ -149,42 +158,37 @@ class ParamsWrapperTest < ActionController::TestCase
   def test_nested_params
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'person' => { 'username' => 'sikachu' }}
+      post :parse, params: { 'person' => { 'username' => 'sikachu' }}
       assert_parameters({ 'person' => { 'username' => 'sikachu' }, 'user' => {'person' => { 'username' => 'sikachu' }}})
     end
   end
 
   def test_derived_wrapped_keys_from_matching_model
-    User.expects(:respond_to?).with(:attribute_names).returns(true)
-    User.expects(:attribute_names).twice.returns(["username"])
-
-    with_default_wrapper_options do
-      @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
-      assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'username' => 'sikachu' }})
+    assert_called(User, :attribute_names, times: 2, returns: ["username"]) do
+      with_default_wrapper_options do
+        @request.env['CONTENT_TYPE'] = 'application/json'
+        post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
+        assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'username' => 'sikachu' }})
+      end
     end
   end
 
   def test_derived_wrapped_keys_from_specified_model
     with_default_wrapper_options do
-      Person.expects(:respond_to?).with(:attribute_names).returns(true)
-      Person.expects(:attribute_names).twice.returns(["username"])
-
-      UsersController.wrap_parameters Person
+      assert_called(Person, :attribute_names, times: 2, returns: ["username"]) do
+        UsersController.wrap_parameters Person
 
-      @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
-      assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'person' => { 'username' => 'sikachu' }})
+        @request.env['CONTENT_TYPE'] = 'application/json'
+        post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
+        assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'person' => { 'username' => 'sikachu' }})
+      end
     end
   end
 
   def test_not_wrapping_abstract_model
-    User.expects(:respond_to?).with(:attribute_names).returns(true)
-    User.expects(:attribute_names).returns([])
-
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+      post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
       assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'username' => 'sikachu', 'title' => 'Developer' }})
     end
   end
@@ -192,7 +196,7 @@ class ParamsWrapperTest < ActionController::TestCase
   def test_preserves_query_string_params
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      get :parse, { 'user' => { 'username' => 'nixon' } }
+      get :parse, params: { 'user' => { 'username' => 'nixon' } }
       assert_parameters(
         {'user' => { 'username' => 'nixon' } }
       )
@@ -202,7 +206,7 @@ class ParamsWrapperTest < ActionController::TestCase
   def test_empty_parameter_set
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, {}
+      post :parse, params: {}
       assert_parameters(
         {'user' => { } }
       )
@@ -249,7 +253,7 @@ class NamespacedParamsWrapperTest < ActionController::TestCase
   def test_derived_name_from_controller
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu' }
+      post :parse, params: { 'username' => 'sikachu' }
       assert_parameters({'username' => 'sikachu', 'user' => { 'username' => 'sikachu' }})
     end
   end
@@ -259,7 +263,7 @@ class NamespacedParamsWrapperTest < ActionController::TestCase
     begin
       with_default_wrapper_options do
         @request.env['CONTENT_TYPE'] = 'application/json'
-        post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+        post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
         assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'username' => 'sikachu' }})
       end
     ensure
@@ -272,7 +276,7 @@ class NamespacedParamsWrapperTest < ActionController::TestCase
     begin
       with_default_wrapper_options do
         @request.env['CONTENT_TYPE'] = 'application/json'
-        post :parse, { 'username' => 'sikachu', 'title' => 'Developer' }
+        post :parse, params: { 'username' => 'sikachu', 'title' => 'Developer' }
         assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'title' => 'Developer' }})
       end
     ensure
@@ -299,7 +303,7 @@ class AnonymousControllerParamsWrapperTest < ActionController::TestCase
   def test_does_not_implicitly_wrap_params
     with_default_wrapper_options do
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu' }
+      post :parse, params: { 'username' => 'sikachu' }
       assert_parameters({ 'username' => 'sikachu' })
     end
   end
@@ -308,7 +312,7 @@ class AnonymousControllerParamsWrapperTest < ActionController::TestCase
     with_default_wrapper_options do
       @controller.class.wrap_parameters(:name => "guest")
       @request.env['CONTENT_TYPE'] = 'application/json'
-      post :parse, { 'username' => 'sikachu' }
+      post :parse, params: { 'username' => 'sikachu' }
       assert_parameters({ 'username' => 'sikachu', 'guest' => { 'username' => 'sikachu' }})
     end
   end
@@ -344,7 +348,7 @@ class IrregularInflectionParamsWrapperTest < ActionController::TestCase
 
       with_default_wrapper_options do
         @request.env['CONTENT_TYPE'] = 'application/json'
-        post :parse, { 'username' => 'sikachu', 'test_attr' => 'test_value' }
+        post :parse, params: { 'username' => 'sikachu', 'test_attr' => 'test_value' }
         assert_parameters({ 'username' => 'sikachu', 'test_attr' => 'test_value', 'paramswrappernews_item' => { 'test_attr' => 'test_value' }})
       end
     end
diff --git a/actionpack/test/controller/permitted_params_test.rb b/actionpack/test/controller/permitted_params_test.rb
index f46249d712..7c753a45a5 100644
--- a/actionpack/test/controller/permitted_params_test.rb
+++ b/actionpack/test/controller/permitted_params_test.rb
@@ -2,11 +2,11 @@ require 'abstract_unit'
 
 class PeopleController < ActionController::Base
   def create
-    render text: params[:person].permitted? ? "permitted" : "forbidden"
+    render plain: params[:person].permitted? ? "permitted" : "forbidden"
   end
 
   def create_with_permit
-    render text: params[:person].permit(:name).permitted? ? "permitted" : "forbidden"
+    render plain: params[:person].permit(:name).permitted? ? "permitted" : "forbidden"
   end
 end
 
@@ -14,12 +14,12 @@ class ActionControllerPermittedParamsTest < ActionController::TestCase
   tests PeopleController
 
   test "parameters are forbidden" do
-    post :create, { person: { name: "Mjallo!" } }
+    post :create, params: { person: { name: "Mjallo!" } }
     assert_equal "forbidden", response.body
   end
 
   test "parameters can be permitted and are then not forbidden" do
-    post :create_with_permit, { person: { name: "Mjallo!" } }
+    post :create_with_permit, params: { person: { name: "Mjallo!" } }
     assert_equal "permitted", response.body
   end
 end
diff --git a/actionpack/test/controller/redirect_test.rb b/actionpack/test/controller/redirect_test.rb
index 103ca9c776..631ff7d02a 100644
--- a/actionpack/test/controller/redirect_test.rb
+++ b/actionpack/test/controller/redirect_test.rb
@@ -1,13 +1,10 @@
 require 'abstract_unit'
 
-class WorkshopsController < ActionController::Base
-end
-
 class RedirectController < ActionController::Base
   # empty method not used anywhere to ensure methods like
   # `status` and `location` aren't called on `redirect_to` calls
-  def status; render :text => 'called status'; end
-  def location; render :text => 'called location'; end
+  def status; render plain: 'called status'; end
+  def location; render plain: 'called location'; end
 
   def simple_redirect
     redirect_to :action => "hello_world"
@@ -53,17 +50,12 @@ class RedirectController < ActionController::Base
     redirect_to :controller => 'module_test/module_redirect', :action => "hello_world"
   end
 
-  def redirect_with_assigns
-    @hello = "world"
-    redirect_to :action => "hello_world"
-  end
-
   def redirect_to_url
     redirect_to "http://www.rubyonrails.org/"
   end
 
   def redirect_to_url_with_unescaped_query_string
-    redirect_to "http://dev.rubyonrails.org/query?status=new"
+    redirect_to "http://example.com/query?status=new"
   end
 
   def redirect_to_url_with_complex_scheme
@@ -218,12 +210,6 @@ class RedirectTest < ActionController::TestCase
     assert_redirected_to :controller => 'module_test/module_redirect', :action => 'hello_world'
   end
 
-  def test_redirect_with_assigns
-    get :redirect_with_assigns
-    assert_response :redirect
-    assert_equal "world", assigns["hello"]
-  end
-
   def test_redirect_to_url
     get :redirect_to_url
     assert_response :redirect
@@ -233,7 +219,7 @@ class RedirectTest < ActionController::TestCase
   def test_redirect_to_url_with_unescaped_query_string
     get :redirect_to_url_with_unescaped_query_string
     assert_response :redirect
-    assert_redirected_to "http://dev.rubyonrails.org/query?status=new"
+    assert_redirected_to "http://example.com/query?status=new"
   end
 
   def test_redirect_to_url_with_complex_scheme
@@ -280,15 +266,17 @@ class RedirectTest < ActionController::TestCase
   end
 
   def test_redirect_to_nil
-    assert_raise(ActionController::ActionControllerError) do
+    error = assert_raise(ActionController::ActionControllerError) do
       get :redirect_to_nil
     end
+    assert_equal "Cannot redirect to nil!", error.message
   end
 
   def test_redirect_to_params
-    assert_raise(ActionController::ActionControllerError) do
+    error = assert_raise(ActionController::ActionControllerError) do
       get :redirect_to_params
     end
+    assert_equal "Cannot redirect to a parameter hash!", error.message
   end
 
   def test_redirect_to_with_block
diff --git a/actionpack/test/controller/render_js_test.rb b/actionpack/test/controller/render_js_test.rb
index d550422a2f..6b661de064 100644
--- a/actionpack/test/controller/render_js_test.rb
+++ b/actionpack/test/controller/render_js_test.rb
@@ -22,13 +22,13 @@ class RenderJSTest < ActionController::TestCase
   tests TestController
 
   def test_render_vanilla_js
-    xhr :get, :render_vanilla_js_hello
+    get :render_vanilla_js_hello, xhr: true
     assert_equal "alert('hello')", @response.body
     assert_equal "text/javascript", @response.content_type
   end
 
   def test_should_render_js_partial
-    xhr :get, :show_partial, :format => 'js'
+    get :show_partial, format: 'js', xhr: true
     assert_equal 'partial js', @response.body
   end
 end
diff --git a/actionpack/test/controller/render_json_test.rb b/actionpack/test/controller/render_json_test.rb
index ada978aa11..3773900cc4 100644
--- a/actionpack/test/controller/render_json_test.rb
+++ b/actionpack/test/controller/render_json_test.rb
@@ -28,7 +28,7 @@ class RenderJsonTest < ActionController::TestCase
     end
 
     def render_json_render_to_string
-      render :text => render_to_string(:json => '[]')
+      render plain: render_to_string(json: '[]')
     end
 
     def render_json_hello_world
@@ -100,13 +100,13 @@ class RenderJsonTest < ActionController::TestCase
   end
 
   def test_render_json_with_callback
-    xhr :get, :render_json_hello_world_with_callback
+    get :render_json_hello_world_with_callback, xhr: true
     assert_equal '/**/alert({"hello":"world"})', @response.body
     assert_equal 'text/javascript', @response.content_type
   end
 
   def test_render_json_with_custom_content_type
-    xhr :get, :render_json_with_custom_content_type
+    get :render_json_with_custom_content_type, xhr: true
     assert_equal '{"hello":"world"}', @response.body
     assert_equal 'text/javascript', @response.content_type
   end
diff --git a/actionpack/test/controller/render_other_test.rb b/actionpack/test/controller/render_other_test.rb
index af50e11261..1f5215ac55 100644
--- a/actionpack/test/controller/render_other_test.rb
+++ b/actionpack/test/controller/render_other_test.rb
@@ -12,7 +12,7 @@ class RenderOtherTest < ActionController::TestCase
 
   def test_using_custom_render_option
     ActionController.add_renderer :simon do |says, options|
-      self.content_type  = Mime::TEXT
+      self.content_type  = Mime[:text]
       self.response_body = "Simon says: #{says}"
     end
 
diff --git a/actionpack/test/controller/render_test.rb b/actionpack/test/controller/render_test.rb
index 108a35f59f..256ebf6a07 100644
--- a/actionpack/test/controller/render_test.rb
+++ b/actionpack/test/controller/render_test.rb
@@ -1,6 +1,5 @@
 require 'abstract_unit'
 require 'controller/fake_models'
-require 'pathname'
 
 class TestControllerWithExtraEtags < ActionController::Base
   etag { nil  }
@@ -10,20 +9,25 @@ class TestControllerWithExtraEtags < ActionController::Base
   etag { nil  }
 
   def fresh
-    render text: "stale" if stale?(etag: '123', template: false)
+    render plain: "stale" if stale?(etag: '123', template: false)
   end
 
   def array
-    render text: "stale" if stale?(etag: %w(1 2 3), template: false)
+    render plain: "stale" if stale?(etag: %w(1 2 3), template: false)
   end
 
   def with_template
     if stale? template: 'test/hello_world'
-      render text: 'stale'
+      render plain: 'stale'
     end
   end
 end
 
+class ImplicitRenderTestController < ActionController::Base
+  def empty_action
+  end
+end
+
 class TestController < ActionController::Base
   protect_from_forgery
 
@@ -58,6 +62,27 @@ class TestController < ActionController::Base
     end
   end
 
+  class Collection
+    def initialize(records)
+      @records = records
+    end
+
+    def maximum(attribute)
+      @records.max_by(&attribute).public_send(attribute)
+    end
+  end
+
+  def conditional_hello_with_collection_of_records
+    ts = Time.now.utc.beginning_of_day
+
+    record = Struct.new(:updated_at, :cache_key).new(ts, "foo/123")
+    old_record = Struct.new(:updated_at, :cache_key).new(ts - 1.day, "bar/123")
+
+    if stale?(Collection.new([record, old_record]))
+      render action: 'hello_world'
+    end
+  end
+
   def conditional_hello_with_expires_in
     expires_in 60.1.seconds
     render :action => 'hello_world'
@@ -99,6 +124,10 @@ class TestController < ActionController::Base
     render :action => 'hello_world'
   end
 
+  def respond_with_empty_body
+    render nothing: true
+  end
+
   def conditional_hello_with_bangs
     render :action => 'hello_world'
   end
@@ -108,6 +137,14 @@ class TestController < ActionController::Base
     fresh_when(:last_modified => Time.now.utc.beginning_of_day, :etag => [ :foo, 123 ])
   end
 
+  def head_with_status_hash
+    head status: :created
+  end
+
+  def head_with_hash_does_not_include_status
+    head warning: :deprecated
+  end
+
   def head_created
     head :created
   end
@@ -121,37 +158,42 @@ class TestController < ActionController::Base
   end
 
   def head_with_location_header
-    head :location => "/foo"
+    head :ok, :location => "/foo"
   end
 
   def head_with_location_object
-    head :location => Customer.new("david", 1)
+    head :ok, :location => Customer.new("david", 1)
   end
 
   def head_with_symbolic_status
-    head :status => params[:status].intern
+    head params[:status].intern
   end
 
   def head_with_integer_status
-    head :status => params[:status].to_i
+    head params[:status].to_i
   end
 
   def head_with_string_status
-    head :status => params[:status]
+    head params[:status]
   end
 
   def head_with_custom_header
-    head :x_custom_header => "something"
+    head :ok, :x_custom_header => "something"
   end
 
   def head_with_www_authenticate_header
-    head 'WWW-Authenticate' => 'something'
+    head :ok, 'WWW-Authenticate' => 'something'
   end
 
   def head_with_status_code_first
     head :forbidden, :x_custom_header => "something"
   end
 
+  def head_and_return
+    head :ok and return
+    raise 'should not reach this line'
+  end
+
   def head_with_no_content
     # Fill in the headers with dummy data to make
     # sure they get removed during the testing
@@ -192,8 +234,6 @@ class MetalTestController < ActionController::Metal
   include AbstractController::Rendering
   include ActionView::Rendering
   include ActionController::Rendering
-  include ActionController::RackDelegation
-
 
   def accessing_logger_in_template
     render :inline =>  "<%= logger.class %>"
@@ -244,11 +284,18 @@ class ExpiresInRenderTest < ActionController::TestCase
     assert_match(/no-transform/, @response.headers["Cache-Control"])
   end
 
+  def test_render_nothing_deprecated
+    assert_deprecated do
+      get :respond_with_empty_body
+    end
+  end
+
   def test_date_header_when_expires_in
     time = Time.mktime(2011,10,30)
-    Time.stubs(:now).returns(time)
-    get :conditional_hello_with_expires_in
-    assert_equal Time.now.httpdate, @response.headers["Date"]
+    Time.stub :now, time do
+      get :conditional_hello_with_expires_in
+      assert_equal Time.now.httpdate, @response.headers["Date"]
+    end
   end
 end
 
@@ -288,7 +335,6 @@ class LastModifiedRenderTest < ActionController::TestCase
     assert_equal @last_modified, @response.headers['Last-Modified']
   end
 
-
   def test_responds_with_last_modified_with_record
     get :conditional_hello_with_record
     assert_equal @last_modified, @response.headers['Last-Modified']
@@ -299,6 +345,7 @@ class LastModifiedRenderTest < ActionController::TestCase
     get :conditional_hello_with_record
     assert_equal 304, @response.status.to_i
     assert @response.body.blank?
+    assert_not_nil @response.etag
     assert_equal @last_modified, @response.headers['Last-Modified']
   end
 
@@ -317,6 +364,34 @@ class LastModifiedRenderTest < ActionController::TestCase
     assert_equal @last_modified, @response.headers['Last-Modified']
   end
 
+  def test_responds_with_last_modified_with_collection_of_records
+    get :conditional_hello_with_collection_of_records
+    assert_equal @last_modified, @response.headers['Last-Modified']
+  end
+
+  def test_request_not_modified_with_collection_of_records
+    @request.if_modified_since = @last_modified
+    get :conditional_hello_with_collection_of_records
+    assert_equal 304, @response.status.to_i
+    assert @response.body.blank?
+    assert_equal @last_modified, @response.headers['Last-Modified']
+  end
+
+  def test_request_not_modified_but_etag_differs_with_collection_of_records
+    @request.if_modified_since = @last_modified
+    @request.if_none_match = "234"
+    get :conditional_hello_with_collection_of_records
+    assert_response :success
+  end
+
+  def test_request_modified_with_collection_of_records
+    @request.if_modified_since = 'Thu, 16 Jul 2008 00:00:00 GMT'
+    get :conditional_hello_with_collection_of_records
+    assert_equal 200, @response.status.to_i
+    assert @response.body.present?
+    assert_equal @last_modified, @response.headers['Last-Modified']
+  end
+
   def test_request_with_bang_gets_last_modified
     get :conditional_hello_with_bangs
     assert_equal @last_modified, @response.headers['Last-Modified']
@@ -399,6 +474,15 @@ class MetalRenderTest < ActionController::TestCase
   end
 end
 
+class ImplicitRenderTest < ActionController::TestCase
+  tests ImplicitRenderTestController
+
+  def test_implicit_no_content_response
+    get :empty_action
+    assert_response :no_content
+  end
+end
+
 class HeadRenderTest < ActionController::TestCase
   tests TestController
 
@@ -412,6 +496,19 @@ class HeadRenderTest < ActionController::TestCase
     assert_response :created
   end
 
+  def test_passing_hash_to_head_as_first_parameter_deprecated
+    assert_deprecated do
+      get :head_with_status_hash
+    end
+  end
+
+  def test_head_with_default_value_is_deprecated
+    assert_deprecated do
+      get :head_with_hash_does_not_include_status
+      assert_response :ok
+    end
+  end
+
   def test_head_created_with_application_json_content_type
     post :head_created_with_application_json_content_type
     assert @response.body.blank?
@@ -462,21 +559,21 @@ class HeadRenderTest < ActionController::TestCase
   end
 
   def test_head_with_symbolic_status
-    get :head_with_symbolic_status, :status => "ok"
+    get :head_with_symbolic_status, params: { status: "ok" }
     assert_equal 200, @response.status
     assert_response :ok
 
-    get :head_with_symbolic_status, :status => "not_found"
+    get :head_with_symbolic_status, params: { status: "not_found" }
     assert_equal 404, @response.status
     assert_response :not_found
 
-    get :head_with_symbolic_status, :status => "no_content"
+    get :head_with_symbolic_status, params: { status: "no_content" }
     assert_equal 204, @response.status
     assert !@response.headers.include?('Content-Length')
     assert_response :no_content
 
     Rack::Utils::SYMBOL_TO_STATUS_CODE.each do |status, code|
-      get :head_with_symbolic_status, :status => status.to_s
+      get :head_with_symbolic_status, params: { status: status.to_s }
       assert_equal code, @response.response_code
       assert_response status
     end
@@ -484,7 +581,7 @@ class HeadRenderTest < ActionController::TestCase
 
   def test_head_with_integer_status
     Rack::Utils::HTTP_STATUS_CODES.each do |code, message|
-      get :head_with_integer_status, :status => code.to_s
+      get :head_with_integer_status, params: { status: code.to_s }
       assert_equal message, @response.message
     end
   end
@@ -498,7 +595,7 @@ class HeadRenderTest < ActionController::TestCase
   end
 
   def test_head_with_string_status
-    get :head_with_string_status, :status => "404 Eat Dirt"
+    get :head_with_string_status, params: { status: "404 Eat Dirt" }
     assert_equal 404, @response.response_code
     assert_equal "Not Found", @response.message
     assert_response :not_found
@@ -511,4 +608,63 @@ class HeadRenderTest < ActionController::TestCase
     assert_equal "something", @response.headers["X-Custom-Header"]
     assert_response :forbidden
   end
+
+  def test_head_returns_truthy_value
+    assert_nothing_raised do
+      get :head_and_return
+    end
+  end
+end
+
+class HttpCacheForeverTest < ActionController::TestCase
+  class HttpCacheForeverController < ActionController::Base
+    def cache_me_forever
+      http_cache_forever(public: params[:public], version: params[:version] || 'v1') do
+        render plain: 'hello'
+      end
+    end
+  end
+
+  tests HttpCacheForeverController
+
+  def test_cache_with_public
+    get :cache_me_forever, params: {public: true}
+    assert_equal "max-age=#{100.years}, public", @response.headers["Cache-Control"]
+    assert_not_nil @response.etag
+  end
+
+  def test_cache_with_private
+    get :cache_me_forever
+    assert_equal "max-age=#{100.years}, private", @response.headers["Cache-Control"]
+    assert_not_nil @response.etag
+    assert_response :success
+  end
+
+  def test_cache_response_code_with_if_modified_since
+    get :cache_me_forever
+    assert_response :success
+    @request.if_modified_since = @response.headers['Last-Modified']
+    get :cache_me_forever
+    assert_response :not_modified
+  end
+
+  def test_cache_response_code_with_etag
+    get :cache_me_forever
+    assert_response :success
+    @request.if_modified_since = @response.headers['Last-Modified']
+    @request.if_none_match = @response.etag
+
+    get :cache_me_forever
+    assert_response :not_modified
+    @request.if_modified_since = @response.headers['Last-Modified']
+    @request.if_none_match = @response.etag
+
+    get :cache_me_forever, params: {version: 'v2'}
+    assert_response :success
+    @request.if_modified_since = @response.headers['Last-Modified']
+    @request.if_none_match = @response.etag
+
+    get :cache_me_forever, params: {version: 'v2'}
+    assert_response :not_modified
+  end
 end
diff --git a/actionpack/test/controller/render_xml_test.rb b/actionpack/test/controller/render_xml_test.rb
index 4f280c4bec..f0fd7ddc5e 100644
--- a/actionpack/test/controller/render_xml_test.rb
+++ b/actionpack/test/controller/render_xml_test.rb
@@ -81,7 +81,7 @@ class RenderXmlTest < ActionController::TestCase
   end
 
   def test_should_render_formatted_xml_erb_template
-    get :formatted_xml_erb, :format => :xml
+    get :formatted_xml_erb, format: :xml
     assert_equal '<test>passed formatted xml erb</test>', @response.body
   end
 
@@ -91,7 +91,7 @@ class RenderXmlTest < ActionController::TestCase
   end
 
   def test_should_use_implicit_content_type
-    get :implicit_content_type, :format => 'atom'
-    assert_equal Mime::ATOM, @response.content_type
+    get :implicit_content_type, format: 'atom'
+    assert_equal Mime[:atom], @response.content_type
   end
 end
diff --git a/actionpack/test/controller/renderer_test.rb b/actionpack/test/controller/renderer_test.rb
new file mode 100644
index 0000000000..16d24fa82a
--- /dev/null
+++ b/actionpack/test/controller/renderer_test.rb
@@ -0,0 +1,94 @@
+require 'abstract_unit'
+
+class RendererTest < ActiveSupport::TestCase
+  test 'action controller base has a renderer' do
+    assert ActionController::Base.renderer
+  end
+
+  test 'creating with a controller' do
+    controller = CommentsController
+    renderer   = ActionController::Renderer.for controller
+
+    assert_equal controller, renderer.controller
+  end
+
+  test 'creating from a controller' do
+    controller = AccountsController
+    renderer   = controller.renderer
+
+    assert_equal controller, renderer.controller
+  end
+
+  test 'rendering with a class renderer' do
+    renderer = ApplicationController.renderer
+    content  = renderer.render template: 'ruby_template'
+
+    assert_equal 'Hello from Ruby code', content
+  end
+
+  test 'rendering with an instance renderer' do
+    renderer = ApplicationController.renderer.new
+    content  = renderer.render file: 'test/hello_world'
+
+    assert_equal 'Hello world!', content
+  end
+
+  test 'rendering with a controller class' do
+    assert_equal 'Hello world!', ApplicationController.render('test/hello_world')
+  end
+
+  test 'rendering with locals' do
+    renderer = ApplicationController.renderer
+    content  = renderer.render template: 'test/render_file_with_locals',
+                               locals: { secret: 'bar' }
+
+    assert_equal "The secret is bar\n", content
+  end
+
+  test 'rendering with assigns' do
+    renderer = ApplicationController.renderer
+    content  = renderer.render template: 'test/render_file_with_ivar',
+                               assigns: { secret: 'foo' }
+
+    assert_equal "The secret is foo\n", content
+  end
+
+  test 'rendering with custom env' do
+    renderer = ApplicationController.renderer.new method: 'post'
+    content  = renderer.render inline: '<%= request.post? %>'
+
+    assert_equal 'true', content
+  end
+
+  test 'rendering with defaults' do
+    renderer = ApplicationController.renderer.new https: true
+    content = renderer.render inline: '<%= request.ssl? %>'
+
+    assert_equal 'true', content
+  end
+
+  test 'same defaults from the same controller' do
+    renderer_defaults = ->(controller) { controller.renderer.defaults }
+
+    assert_equal renderer_defaults[AccountsController], renderer_defaults[AccountsController]
+    assert_equal renderer_defaults[AccountsController], renderer_defaults[CommentsController]
+  end
+
+  test 'rendering with different formats' do
+    html = 'Hello world!'
+    xml  = "<p>Hello world!</p>\n"
+
+    assert_equal html, render['respond_to/using_defaults']
+    assert_equal xml,  render['respond_to/using_defaults.xml.builder']
+    assert_equal xml,  render['respond_to/using_defaults', formats: :xml]
+  end
+
+  test 'rendering with helpers' do
+    assert_equal "<p>1\n<br />2</p>", render[inline: '<%= simple_format "1\n2" %>']
+  end
+
+  private
+    def render
+      @render ||= ApplicationController.renderer.method(:render)
+    end
+end
diff --git a/actionpack/test/controller/request/test_request_test.rb b/actionpack/test/controller/request/test_request_test.rb
index e624f11773..e5d698d5c2 100644
--- a/actionpack/test/controller/request/test_request_test.rb
+++ b/actionpack/test/controller/request/test_request_test.rb
@@ -1,11 +1,7 @@
 require 'abstract_unit'
 require 'stringio'
 
-class ActionController::TestRequestTest < ActiveSupport::TestCase
-
-  def setup
-    @request = ActionController::TestRequest.new
-  end
+class ActionController::TestRequestTest < ActionController::TestCase
 
   def test_test_request_has_session_options_initialized
     assert @request.session_options
@@ -24,12 +20,4 @@ class ActionController::TestRequestTest < ActiveSupport::TestCase
     end
   end
 
-  def test_session_id_exists_by_default
-    assert_not_nil(@request.session_options[:id])
-  end
-
-  def test_session_id_different_on_each_call
-    assert_not_equal(@request.session_options[:id], ActionController::TestRequest.new.session_options[:id])
-  end
-
 end
diff --git a/actionpack/test/controller/request_forgery_protection_test.rb b/actionpack/test/controller/request_forgery_protection_test.rb
index ea2d35c3f8..94ffbe3cd0 100644
--- a/actionpack/test/controller/request_forgery_protection_test.rb
+++ b/actionpack/test/controller/request_forgery_protection_test.rb
@@ -1,5 +1,4 @@
 require 'abstract_unit'
-require 'digest/sha1'
 require "active_support/log_subscriber/test_helper"
 
 # common controller actions
@@ -12,30 +11,14 @@ module RequestForgeryProtectionActions
     render :inline => "<%= button_to('New', '/') %>"
   end
 
-  def external_form
-    render :inline => "<%= form_tag('http://farfar.away/form', :authenticity_token => 'external_token') {} %>"
-  end
-
-  def external_form_without_protection
-    render :inline => "<%= form_tag('http://farfar.away/form', :authenticity_token => false) {} %>"
-  end
-
   def unsafe
-    render :text => 'pwn'
+    render plain: 'pwn'
   end
 
   def meta
     render :inline => "<%= csrf_meta_tags %>"
   end
 
-  def external_form_for
-    render :inline => "<%= form_for(:some_resource, :authenticity_token => 'external_token') {} %>"
-  end
-
-  def form_for_without_protection
-    render :inline => "<%= form_for(:some_resource, :authenticity_token => false ) {} %>"
-  end
-
   def form_for_remote
     render :inline => "<%= form_for(:some_resource, :remote => true ) {} %>"
   end
@@ -70,7 +53,6 @@ module RequestForgeryProtectionActions
     negotiate_same_origin
   end
 
-  def rescue_action(e) raise e end
 end
 
 # sample controllers
@@ -89,17 +71,17 @@ class RequestForgeryProtectionControllerUsingNullSession < ActionController::Bas
 
   def signed
     cookies.signed[:foo] = 'bar'
-    render :nothing => true
+    head :ok
   end
 
   def encrypted
     cookies.encrypted[:foo] = 'bar'
-    render :nothing => true
+    head :ok
   end
 
   def try_to_reset_session
     reset_session
-    render :nothing => true
+    head :ok
   end
 end
 
@@ -149,10 +131,7 @@ end
 # common test methods
 module RequestForgeryProtectionTests
   def setup
-    @token      = "cf50faa3fe97702ca1ae"
-    @controller.stubs(:form_authenticity_token).returns(@token)
-    @controller.stubs(:valid_authenticity_token?).with{ |_, t| t == @token }.returns(true)
-    @controller.stubs(:valid_authenticity_token?).with{ |_, t| t != @token }.returns(false)
+    @token = Base64.strict_encode64('railstestrailstestrailstestrails')
     @old_request_forgery_protection_token = ActionController::Base.request_forgery_protection_token
     ActionController::Base.request_forgery_protection_token = :custom_authenticity_token
   end
@@ -162,17 +141,21 @@ module RequestForgeryProtectionTests
   end
 
   def test_should_render_form_with_token_tag
-    assert_not_blocked do
-      get :index
+    @controller.stub :form_authenticity_token, @token do
+      assert_not_blocked do
+        get :index
+      end
+      assert_select 'form>input[name=?][value=?]', 'custom_authenticity_token', @token
     end
-    assert_select 'form>input[name=?][value=?]', 'custom_authenticity_token', @token
   end
 
   def test_should_render_button_to_with_token_tag
-    assert_not_blocked do
-      get :show_button
+    @controller.stub :form_authenticity_token, @token do
+      assert_not_blocked do
+        get :show_button
+      end
+      assert_select 'form>input[name=?][value=?]', 'custom_authenticity_token', @token
     end
-    assert_select 'form>input[name=?][value=?]', 'custom_authenticity_token', @token
   end
 
   def test_should_render_form_without_token_tag_if_remote
@@ -216,17 +199,21 @@ module RequestForgeryProtectionTests
   end
 
   def test_should_render_form_with_token_tag_if_remote_and_authenticity_token_requested
-    assert_not_blocked do
-      get :form_for_remote_with_token
+    @controller.stub :form_authenticity_token, @token do
+      assert_not_blocked do
+        get :form_for_remote_with_token
+      end
+      assert_select 'form>input[name=?][value=?]', 'custom_authenticity_token', @token
     end
-    assert_select 'form>input[name=?][value=?]', 'custom_authenticity_token', @token
   end
 
   def test_should_render_form_with_token_tag_with_authenticity_token_requested
-    assert_not_blocked do
-      get :form_for_with_token
+    @controller.stub :form_authenticity_token, @token do
+      assert_not_blocked do
+        get :form_for_with_token
+      end
+      assert_select 'form>input[name=?][value=?]', 'custom_authenticity_token', @token
     end
-    assert_select 'form>input[name=?][value=?]', 'custom_authenticity_token', @token
   end
 
   def test_should_allow_get
@@ -262,41 +249,57 @@ module RequestForgeryProtectionTests
   end
 
   def test_should_not_allow_xhr_post_without_token
-    assert_blocked { xhr :post, :index }
+    assert_blocked { post :index, xhr: true }
   end
 
   def test_should_allow_post_with_token
-    assert_not_blocked { post :index, :custom_authenticity_token => @token }
+    session[:_csrf_token] = @token
+    @controller.stub :form_authenticity_token, @token do
+      assert_not_blocked { post :index, params: { custom_authenticity_token: @token } }
+    end
   end
 
   def test_should_allow_patch_with_token
-    assert_not_blocked { patch :index, :custom_authenticity_token => @token }
+    session[:_csrf_token] = @token
+    @controller.stub :form_authenticity_token, @token do
+      assert_not_blocked { patch :index, params: { custom_authenticity_token: @token } }
+    end
   end
 
   def test_should_allow_put_with_token
-    assert_not_blocked { put :index, :custom_authenticity_token => @token }
+    session[:_csrf_token] = @token
+    @controller.stub :form_authenticity_token, @token do
+      assert_not_blocked { put :index, params: { custom_authenticity_token: @token } }
+    end
   end
 
   def test_should_allow_delete_with_token
-    assert_not_blocked { delete :index, :custom_authenticity_token => @token }
+    session[:_csrf_token] = @token
+    @controller.stub :form_authenticity_token, @token do
+      assert_not_blocked { delete :index, params: { custom_authenticity_token: @token } }
+    end
   end
 
   def test_should_allow_post_with_token_in_header
+    session[:_csrf_token] = @token
     @request.env['HTTP_X_CSRF_TOKEN'] = @token
     assert_not_blocked { post :index }
   end
 
   def test_should_allow_delete_with_token_in_header
+    session[:_csrf_token] = @token
     @request.env['HTTP_X_CSRF_TOKEN'] = @token
     assert_not_blocked { delete :index }
   end
 
   def test_should_allow_patch_with_token_in_header
+    session[:_csrf_token] = @token
     @request.env['HTTP_X_CSRF_TOKEN'] = @token
     assert_not_blocked { patch :index }
   end
 
   def test_should_allow_put_with_token_in_header
+    session[:_csrf_token] = @token
     @request.env['HTTP_X_CSRF_TOKEN'] = @token
     assert_not_blocked { put :index }
   end
@@ -340,21 +343,22 @@ module RequestForgeryProtectionTests
       get :negotiate_same_origin
     end
 
-    assert_cross_origin_not_blocked { xhr :get, :same_origin_js }
-    assert_cross_origin_not_blocked { xhr :get, :same_origin_js, format: 'js' }
+    assert_cross_origin_not_blocked { get :same_origin_js, xhr: true }
+    assert_cross_origin_not_blocked { get :same_origin_js, xhr: true, format: 'js'}
     assert_cross_origin_not_blocked do
       @request.accept = 'text/javascript'
-      xhr :get, :negotiate_same_origin
+      get :negotiate_same_origin, xhr: true
     end
   end
 
   # Allow non-GET requests since GET is all a remote <script> tag can muster.
   def test_should_allow_non_get_js_without_xhr_header
-    assert_cross_origin_not_blocked { post :same_origin_js, custom_authenticity_token: @token }
-    assert_cross_origin_not_blocked { post :same_origin_js, format: 'js', custom_authenticity_token: @token }
+    session[:_csrf_token] = @token
+    assert_cross_origin_not_blocked { post :same_origin_js, params: { custom_authenticity_token: @token } }
+    assert_cross_origin_not_blocked { post :same_origin_js, params: { format: 'js', custom_authenticity_token: @token } }
     assert_cross_origin_not_blocked do
       @request.accept = 'text/javascript'
-      post :negotiate_same_origin, custom_authenticity_token: @token
+      post :negotiate_same_origin, params: { custom_authenticity_token: @token}
     end
   end
 
@@ -366,11 +370,17 @@ module RequestForgeryProtectionTests
       get :negotiate_cross_origin
     end
 
-    assert_cross_origin_not_blocked { xhr :get, :cross_origin_js }
-    assert_cross_origin_not_blocked { xhr :get, :cross_origin_js, format: 'js' }
+    assert_cross_origin_not_blocked { get :cross_origin_js, xhr: true }
+    assert_cross_origin_not_blocked { get :cross_origin_js, xhr: true, format: 'js' }
     assert_cross_origin_not_blocked do
       @request.accept = 'text/javascript'
-      xhr :get, :negotiate_cross_origin
+      get :negotiate_cross_origin, xhr: true
+    end
+  end
+
+  def test_should_not_raise_error_if_token_is_not_a_string
+    assert_blocked do
+      patch :index, params: { custom_authenticity_token: { foo: 'bar' } }
     end
   end
 
@@ -412,11 +422,13 @@ class RequestForgeryProtectionControllerUsingResetSessionTest < ActionController
   end
 
   test 'should emit a csrf-param meta tag and a csrf-token meta tag' do
-    @controller.stubs(:form_authenticity_token).returns(@token + '<=?')
-    get :meta
-    assert_select 'meta[name=?][content=?]', 'csrf-param', 'custom_authenticity_token'
-    assert_select 'meta[name=?]', 'csrf-token'
-    assert_match(/cf50faa3fe97702ca1ae&lt;=\?/, @response.body)
+    @controller.stub :form_authenticity_token, @token + '<=?' do
+      get :meta
+      assert_select 'meta[name=?][content=?]', 'csrf-param', 'custom_authenticity_token'
+      assert_select 'meta[name=?]', 'csrf-token'
+      regexp = "#{@token}&lt;=\?"
+      assert_match(/#{regexp}/, @response.body)
+    end
   end
 end
 
@@ -494,32 +506,37 @@ end
 class FreeCookieControllerTest < ActionController::TestCase
   def setup
     @controller = FreeCookieController.new
-    @request    = ActionController::TestRequest.new
-    @response   = ActionController::TestResponse.new
     @token      = "cf50faa3fe97702ca1ae"
-
-    SecureRandom.stubs(:base64).returns(@token)
+    super
   end
 
   def test_should_not_render_form_with_token_tag
-    get :index
-    assert_select 'form>div>input[name=?][value=?]', 'authenticity_token', @token, false
+    SecureRandom.stub :base64, @token do
+      get :index
+      assert_select 'form>div>input[name=?][value=?]', 'authenticity_token', @token, false
+    end
   end
 
   def test_should_not_render_button_to_with_token_tag
-    get :show_button
-    assert_select 'form>div>input[name=?][value=?]', 'authenticity_token', @token, false
+    SecureRandom.stub :base64, @token do
+      get :show_button
+      assert_select 'form>div>input[name=?][value=?]', 'authenticity_token', @token, false
+    end
   end
 
   def test_should_allow_all_methods_without_token
-    [:post, :patch, :put, :delete].each do |method|
-      assert_nothing_raised { send(method, :index)}
+    SecureRandom.stub :base64, @token do
+      [:post, :patch, :put, :delete].each do |method|
+        assert_nothing_raised { send(method, :index)}
+      end
     end
   end
 
   test 'should not emit a csrf-token meta tag' do
-    get :meta
-    assert @response.body.blank?
+    SecureRandom.stub :base64, @token do
+      get :meta
+      assert @response.body.blank?
+    end
   end
 end
 
@@ -540,11 +557,11 @@ class CustomAuthenticityParamControllerTest < ActionController::TestCase
 
   def test_should_not_warn_if_form_authenticity_param_matches_form_authenticity_token
     ActionController::Base.logger = @logger
-    @controller.stubs(:valid_authenticity_token?).returns(:true)
-
     begin
-      post :index, :custom_token_name => 'foobar'
-      assert_equal 0, @logger.logged(:warn).size
+      @controller.stub :valid_authenticity_token?, :true do
+        post :index, params: { custom_token_name: 'foobar' }
+        assert_equal 0, @logger.logged(:warn).size
+      end
     ensure
       ActionController::Base.logger = @old_logger
     end
@@ -554,7 +571,7 @@ class CustomAuthenticityParamControllerTest < ActionController::TestCase
     ActionController::Base.logger = @logger
 
     begin
-      post :index, :custom_token_name => 'bazqux'
+      post :index, params: { custom_token_name: 'bazqux' }
       assert_equal 1, @logger.logged(:warn).size
     ensure
       ActionController::Base.logger = @old_logger
diff --git a/actionpack/test/controller/required_params_test.rb b/actionpack/test/controller/required_params_test.rb
index 6803dbbb62..168f64ce41 100644
--- a/actionpack/test/controller/required_params_test.rb
+++ b/actionpack/test/controller/required_params_test.rb
@@ -12,21 +12,21 @@ class ActionControllerRequiredParamsTest < ActionController::TestCase
 
   test "missing required parameters will raise exception" do
     assert_raise ActionController::ParameterMissing do
-      post :create, { magazine: { name: "Mjallo!" } }
+      post :create, params: { magazine: { name: "Mjallo!" } }
     end
 
     assert_raise ActionController::ParameterMissing do
-      post :create, { book: { title: "Mjallo!" } }
+      post :create, params: { book: { title: "Mjallo!" } }
     end
   end
 
   test "required parameters that are present will not raise" do
-    post :create, { book: { name: "Mjallo!" } }
+    post :create, params: { book: { name: "Mjallo!" } }
     assert_response :ok
   end
 
   test "required parameters with false value will not raise" do
-    post :create, { book: { name: false } }
+    post :create, params: { book: { name: false } }
     assert_response :ok
   end
 end
@@ -48,4 +48,21 @@ class ParametersRequireTest < ActiveSupport::TestCase
       ActionController::Parameters.new(person: {}).require(:person)
     end
   end
+
+  test "require array when all required params are present" do
+    safe_params = ActionController::Parameters.new(person: {first_name: 'Gaurish', title: 'Mjallo', city: 'Barcelona'})
+      .require(:person)
+      .require([:first_name, :title])
+
+    assert_kind_of Array, safe_params
+    assert_equal ['Gaurish', 'Mjallo'], safe_params
+  end
+
+  test "require array when a required param is missing" do
+    assert_raises(ActionController::ParameterMissing) do
+      ActionController::Parameters.new(person: {first_name: 'Gaurish', title: nil})
+        .require(:person)
+        .require([:first_name, :title])
+    end
+  end
 end
diff --git a/actionpack/test/controller/rescue_test.rb b/actionpack/test/controller/rescue_test.rb
index 4898b0c57f..f53f061e10 100644
--- a/actionpack/test/controller/rescue_test.rb
+++ b/actionpack/test/controller/rescue_test.rb
@@ -43,29 +43,29 @@ class RescueController < ActionController::Base
   rescue_from NotAllowed, :with => proc { head :forbidden }
   rescue_from 'RescueController::NotAllowedToRescueAsString', :with => proc { head :forbidden }
 
-  rescue_from InvalidRequest, :with => proc { |exception| render :text => exception.message }
-  rescue_from 'InvalidRequestToRescueAsString', :with => proc { |exception| render :text => exception.message }
+  rescue_from InvalidRequest, with: proc { |exception| render plain: exception.message }
+  rescue_from 'InvalidRequestToRescueAsString', with: proc { |exception| render plain: exception.message }
 
   rescue_from BadGateway do
-    head :status => 502
+    head 502
   end
   rescue_from 'BadGatewayToRescueAsString' do
-    head :status => 502
+    head 502
   end
 
   rescue_from ResourceUnavailable do |exception|
-    render :text => exception.message
+    render plain: exception.message
   end
   rescue_from 'ResourceUnavailableToRescueAsString' do |exception|
-    render :text => exception.message
+    render plain: exception.message
   end
 
   rescue_from ActionView::TemplateError do
-    render :text => 'action_view templater error'
+    render plain: 'action_view templater error'
   end
 
   rescue_from IOError do
-    render :text => 'io error'
+    render plain: 'io error'
   end
 
   before_action(only: :before_action_raises) { raise 'umm nice' }
@@ -74,7 +74,7 @@ class RescueController < ActionController::Base
   end
 
   def raises
-    render :text => 'already rendered'
+    render plain: 'already rendered'
     raise "don't panic!"
   end
 
@@ -246,12 +246,15 @@ class RescueControllerTest < ActionController::TestCase
   end
 
   def test_rescue_handler_with_argument
-    @controller.expects(:show_errors).once.with { |e| e.is_a?(Exception) }
-    get :record_invalid
+    assert_called_with @controller, :show_errors, [Exception] do
+      get :record_invalid
+    end
   end
+
   def test_rescue_handler_with_argument_as_string
-    @controller.expects(:show_errors).once.with { |e| e.is_a?(Exception) }
-    get :record_invalid_raise_as_string
+    assert_called_with @controller, :show_errors, [Exception] do
+      get :record_invalid_raise_as_string
+    end
   end
 
   def test_proc_rescue_handler
@@ -302,7 +305,7 @@ class RescueTest < ActionDispatch::IntegrationTest
     rescue_from RecordInvalid, :with => :show_errors
 
     def foo
-      render :text => "foo"
+      render plain: "foo"
     end
 
     def invalid
@@ -315,7 +318,7 @@ class RescueTest < ActionDispatch::IntegrationTest
 
     protected
       def show_errors(exception)
-        render :text => exception.message
+        render plain: exception.message
       end
   end
 
diff --git a/actionpack/test/controller/resources_test.rb b/actionpack/test/controller/resources_test.rb
index 0e15883f43..4490abf7b2 100644
--- a/actionpack/test/controller/resources_test.rb
+++ b/actionpack/test/controller/resources_test.rb
@@ -149,7 +149,7 @@ class ResourcesTest < ActionController::TestCase
         end
       end
 
-      assert_restful_named_routes_for :messages do |options|
+      assert_restful_named_routes_for :messages do
         actions.each_key do |action|
           assert_named_route "/messages/#{action}", "#{action}_messages_path", :action => action
         end
@@ -179,7 +179,7 @@ class ResourcesTest < ActionController::TestCase
         end
       end
 
-      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do |options|
+      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do
         actions.each_key do |action|
           assert_named_route "/threads/1/messages/#{action}", "#{action}_thread_messages_path", :action => action
         end
@@ -206,7 +206,7 @@ class ResourcesTest < ActionController::TestCase
         end
       end
 
-      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do |options|
+      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do
         actions.each_key do |action|
           assert_named_route "/threads/1/messages/#{action}", "#{action}_thread_messages_path", :action => action
         end
@@ -236,7 +236,7 @@ class ResourcesTest < ActionController::TestCase
         end
       end
 
-      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do |options|
+      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do
         actions.each_key do |action|
           assert_named_route "/threads/1/messages/#{action}.xml", "#{action}_thread_messages_path", :action => action, :format => 'xml'
         end
@@ -253,7 +253,7 @@ class ResourcesTest < ActionController::TestCase
           assert_recognizes(options.merge(mark_options), :path => mark_path, :method => method)
         end
 
-        assert_restful_named_routes_for :messages do |options|
+        assert_restful_named_routes_for :messages do
           assert_named_route mark_path, :mark_message_path, mark_options
         end
       end
@@ -278,7 +278,7 @@ class ResourcesTest < ActionController::TestCase
           assert_recognizes(options.merge(mark_options), :path => mark_path, :method => method)
         end
 
-        assert_restful_named_routes_for :messages, :path_names => {:new => 'nuevo'} do |options|
+        assert_restful_named_routes_for :messages, :path_names => {:new => 'nuevo'} do
           assert_named_route mark_path, :mark_message_path, mark_options
         end
       end
@@ -304,7 +304,7 @@ class ResourcesTest < ActionController::TestCase
             assert_recognizes(options.merge(action_options), :path => action_path, :method => method)
           end
 
-          assert_restful_named_routes_for :messages do |options|
+          assert_restful_named_routes_for :messages do
             assert_named_route action_path, "#{action}_message_path".to_sym, action_options
           end
         end
@@ -351,7 +351,7 @@ class ResourcesTest < ActionController::TestCase
         assert_recognizes(options.merge(preview_options), :path => preview_path, :method => :post)
       end
 
-      assert_restful_named_routes_for :messages do |options|
+      assert_restful_named_routes_for :messages do
         assert_named_route preview_path, :preview_new_message_path, preview_options
       end
     end
@@ -373,7 +373,7 @@ class ResourcesTest < ActionController::TestCase
         assert_recognizes(options.merge(preview_options), :path => preview_path, :method => :post)
       end
 
-      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do |options|
+      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do
         assert_named_route preview_path, :preview_new_thread_message_path, preview_options
       end
     end
@@ -395,7 +395,7 @@ class ResourcesTest < ActionController::TestCase
         assert_recognizes(options.merge(preview_options), :path => preview_path, :method => :post)
       end
 
-      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do |options|
+      assert_restful_named_routes_for :messages, :path_prefix => 'threads/1/', :name_prefix => 'thread_', :options => { :thread_id => '1' } do
         assert_named_route preview_path, :preview_new_thread_message_path, preview_options
       end
     end
@@ -505,8 +505,8 @@ class ResourcesTest < ActionController::TestCase
       routes = @routes.routes
       routes.each do |route|
         routes.each do |r|
-          next if route === r # skip the comparison instance
-          assert_not_equal [route.conditions, route.path.spec.to_s], [r.conditions, r.path.spec.to_s]
+          next if route == r # skip the comparison instance
+          assert_not_equal [route.conditions, route.path.spec.to_s, route.verb], [r.conditions, r.path.spec.to_s, r.verb]
         end
       end
     end
@@ -519,9 +519,9 @@ class ResourcesTest < ActionController::TestCase
   end
 
   def test_should_create_multiple_singleton_resource_routes
-    with_singleton_resources :account, :logo do
+    with_singleton_resources :account, :product do
       assert_singleton_restful_for :account
-      assert_singleton_restful_for :logo
+      assert_singleton_restful_for :product
     end
   end
 
@@ -553,7 +553,7 @@ class ResourcesTest < ActionController::TestCase
           assert_recognizes(options.merge(reset_options), :path => reset_path, :method => method)
         end
 
-        assert_singleton_named_routes_for :account do |options|
+        assert_singleton_named_routes_for :account do
           assert_named_route reset_path, :reset_account_path, reset_options
         end
       end
@@ -577,7 +577,7 @@ class ResourcesTest < ActionController::TestCase
             assert_recognizes(options.merge(action_options), :path => action_path, :method => method)
           end
 
-          assert_singleton_named_routes_for :account do |options|
+          assert_singleton_named_routes_for :account do
             assert_named_route action_path, "#{action}_account_path".to_sym, action_options
           end
         end
@@ -1047,9 +1047,31 @@ class ResourcesTest < ActionController::TestCase
     end
   end
 
+  def test_assert_routing_accepts_all_as_a_valid_method
+    with_routing do |set|
+      set.draw do
+        match "/products", to: "products#show", via: :all
+      end
+
+      assert_routing({ method: "all", path: "/products" }, { controller: "products", action: "show" })
+    end
+  end
+
+  def test_assert_routing_fails_when_not_all_http_methods_are_recognized
+    with_routing do |set|
+      set.draw do
+        match "/products", to: "products#show", via: [:get, :post, :put]
+      end
+
+      assert_raises(Minitest::Assertion) do
+        assert_routing({ method: "all", path: "/products" }, { controller: "products", action: "show" })
+      end
+    end
+  end
+
   def test_singleton_resource_name_is_not_singularized
-    with_singleton_resources(:preferences) do
-      assert_singleton_restful_for :preferences
+    with_singleton_resources(:products) do
+      assert_singleton_restful_for :products
     end
   end
 
@@ -1106,14 +1128,14 @@ class ResourcesTest < ActionController::TestCase
     end
 
     def assert_restful_routes_for(controller_name, options = {})
-      options[:options] ||= {}
-      options[:options][:controller] = options[:controller] || controller_name.to_s
+      route_options = (options[:options] ||= {}).dup
+      route_options[:controller] = options[:controller] || controller_name.to_s
 
       if options[:shallow]
         options[:shallow_options] ||= {}
-        options[:shallow_options][:controller] = options[:options][:controller]
+        options[:shallow_options][:controller] = route_options[:controller]
       else
-        options[:shallow_options] = options[:options]
+        options[:shallow_options] = route_options
       end
 
       new_action    = @routes.resources_path_names[:new] || "new"
@@ -1132,7 +1154,7 @@ class ResourcesTest < ActionController::TestCase
       edit_member_path           = "#{member_path}/#{edit_action}"
       formatted_edit_member_path = "#{member_path}/#{edit_action}.xml"
 
-      with_options(options[:options]) do |controller|
+      with_options(route_options) do |controller|
         controller.assert_routing collection_path,            :action => 'index'
         controller.assert_routing new_path,                   :action => 'new'
         controller.assert_routing "#{collection_path}.xml",   :action => 'index',            :format => 'xml'
@@ -1146,23 +1168,23 @@ class ResourcesTest < ActionController::TestCase
         controller.assert_routing formatted_edit_member_path, :action => 'edit', :id => '1', :format => 'xml'
       end
 
-      assert_recognizes(options[:options].merge(:action => 'index'),               :path => collection_path,  :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'new'),                 :path => new_path,         :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'create'),              :path => collection_path,  :method => :post)
+      assert_recognizes(route_options.merge(:action => 'index'),               :path => collection_path,  :method => :get)
+      assert_recognizes(route_options.merge(:action => 'new'),                 :path => new_path,         :method => :get)
+      assert_recognizes(route_options.merge(:action => 'create'),              :path => collection_path,  :method => :post)
       assert_recognizes(options[:shallow_options].merge(:action => 'show',    :id => '1'), :path => member_path,      :method => :get)
       assert_recognizes(options[:shallow_options].merge(:action => 'edit',    :id => '1'), :path => edit_member_path, :method => :get)
       assert_recognizes(options[:shallow_options].merge(:action => 'update',  :id => '1'), :path => member_path,      :method => :put)
       assert_recognizes(options[:shallow_options].merge(:action => 'destroy', :id => '1'), :path => member_path,      :method => :delete)
 
-      assert_recognizes(options[:options].merge(:action => 'index',  :format => 'xml'), :path => "#{collection_path}.xml",   :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'new',    :format => 'xml'), :path => "#{new_path}.xml",          :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'create', :format => 'xml'), :path => "#{collection_path}.xml",   :method => :post)
+      assert_recognizes(route_options.merge(:action => 'index',  :format => 'xml'), :path => "#{collection_path}.xml",   :method => :get)
+      assert_recognizes(route_options.merge(:action => 'new',    :format => 'xml'), :path => "#{new_path}.xml",          :method => :get)
+      assert_recognizes(route_options.merge(:action => 'create', :format => 'xml'), :path => "#{collection_path}.xml",   :method => :post)
       assert_recognizes(options[:shallow_options].merge(:action => 'show',    :id => '1', :format => 'xml'), :path => "#{member_path}.xml",       :method => :get)
       assert_recognizes(options[:shallow_options].merge(:action => 'edit',    :id => '1', :format => 'xml'), :path => formatted_edit_member_path, :method => :get)
       assert_recognizes(options[:shallow_options].merge(:action => 'update',  :id => '1', :format => 'xml'), :path => "#{member_path}.xml",       :method => :put)
       assert_recognizes(options[:shallow_options].merge(:action => 'destroy', :id => '1', :format => 'xml'), :path => "#{member_path}.xml",       :method => :delete)
 
-      yield options[:options] if block_given?
+      yield route_options if block_given?
     end
 
     # test named routes like foo_path and foos_path map to the correct options.
@@ -1173,22 +1195,20 @@ class ResourcesTest < ActionController::TestCase
       end
       singular_name ||= controller_name.to_s.singularize
 
-      options[:options] ||= {}
-      options[:options][:controller] = options[:controller] || controller_name.to_s
+      route_options = (options[:options] ||= {}).dup
+      route_options[:controller] = options[:controller] || controller_name.to_s
 
       if options[:shallow]
         options[:shallow_options] ||= {}
-        options[:shallow_options][:controller] = options[:options][:controller]
+        options[:shallow_options][:controller] = route_options[:controller]
       else
-        options[:shallow_options] = options[:options]
+        options[:shallow_options] = route_options
       end
 
-      @controller = "#{options[:options][:controller].camelize}Controller".constantize.new
-      @controller.singleton_class.send(:include, @routes.url_helpers)
-      @request    = ActionController::TestRequest.new
-      @response   = ActionController::TestResponse.new
-      get :index, options[:options]
-      options[:options].delete :action
+      @controller = "#{route_options[:controller].camelize}Controller".constantize.new
+      @controller.singleton_class.include(@routes.url_helpers)
+      get :index, params: route_options
+      route_options.delete :action
 
       path = "#{options[:as] || controller_name}"
       shallow_path = "/#{options[:shallow] ? options[:namespace] : options[:path_prefix]}#{path}"
@@ -1203,29 +1223,29 @@ class ResourcesTest < ActionController::TestCase
         edit_action = options[:path_names][:edit] || "edit"
       end
 
-      assert_named_route "#{full_path}", "#{name_prefix}#{controller_name}_path", options[:options]
-      assert_named_route "#{full_path}.xml", "#{name_prefix}#{controller_name}_path", options[:options].merge(:format => 'xml')
+      assert_named_route "#{full_path}", "#{name_prefix}#{controller_name}_path", route_options
+      assert_named_route "#{full_path}.xml", "#{name_prefix}#{controller_name}_path", route_options.merge(:format => 'xml')
       assert_named_route "#{shallow_path}/1", "#{shallow_prefix}#{singular_name}_path", options[:shallow_options].merge(:id => '1')
       assert_named_route "#{shallow_path}/1.xml", "#{shallow_prefix}#{singular_name}_path", options[:shallow_options].merge(:id => '1', :format => 'xml')
 
-      assert_named_route "#{full_path}/#{new_action}", "new_#{name_prefix}#{singular_name}_path", options[:options]
-      assert_named_route "#{full_path}/#{new_action}.xml", "new_#{name_prefix}#{singular_name}_path", options[:options].merge(:format => 'xml')
+      assert_named_route "#{full_path}/#{new_action}", "new_#{name_prefix}#{singular_name}_path", route_options
+      assert_named_route "#{full_path}/#{new_action}.xml", "new_#{name_prefix}#{singular_name}_path", route_options.merge(:format => 'xml')
       assert_named_route "#{shallow_path}/1/#{edit_action}", "edit_#{shallow_prefix}#{singular_name}_path", options[:shallow_options].merge(:id => '1')
       assert_named_route "#{shallow_path}/1/#{edit_action}.xml", "edit_#{shallow_prefix}#{singular_name}_path", options[:shallow_options].merge(:id => '1', :format => 'xml')
 
-      yield options[:options] if block_given?
+      yield route_options if block_given?
     end
 
     def assert_singleton_routes_for(singleton_name, options = {})
-      options[:options] ||= {}
-      options[:options][:controller] = options[:controller] || singleton_name.to_s.pluralize
+      route_options = (options[:options] ||= {}).dup
+      route_options[:controller] = options[:controller] || singleton_name.to_s.pluralize
 
       full_path           = "/#{options[:path_prefix]}#{options[:as] || singleton_name}"
       new_path            = "#{full_path}/new"
       edit_path           = "#{full_path}/edit"
       formatted_edit_path = "#{full_path}/edit.xml"
 
-      with_options options[:options] do |controller|
+      with_options route_options do |controller|
         controller.assert_routing full_path,           :action => 'show'
         controller.assert_routing new_path,            :action => 'new'
         controller.assert_routing edit_path,           :action => 'edit'
@@ -1234,42 +1254,41 @@ class ResourcesTest < ActionController::TestCase
         controller.assert_routing formatted_edit_path, :action => 'edit', :format => 'xml'
       end
 
-      assert_recognizes(options[:options].merge(:action => 'show'),    :path => full_path, :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'new'),     :path => new_path,  :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'edit'),    :path => edit_path, :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'create'),  :path => full_path, :method => :post)
-      assert_recognizes(options[:options].merge(:action => 'update'),  :path => full_path, :method => :put)
-      assert_recognizes(options[:options].merge(:action => 'destroy'), :path => full_path, :method => :delete)
+      assert_recognizes(route_options.merge(:action => 'show'),    :path => full_path, :method => :get)
+      assert_recognizes(route_options.merge(:action => 'new'),     :path => new_path,  :method => :get)
+      assert_recognizes(route_options.merge(:action => 'edit'),    :path => edit_path, :method => :get)
+      assert_recognizes(route_options.merge(:action => 'create'),  :path => full_path, :method => :post)
+      assert_recognizes(route_options.merge(:action => 'update'),  :path => full_path, :method => :put)
+      assert_recognizes(route_options.merge(:action => 'destroy'), :path => full_path, :method => :delete)
 
-      assert_recognizes(options[:options].merge(:action => 'show',    :format => 'xml'), :path => "#{full_path}.xml",  :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'new',     :format => 'xml'), :path => "#{new_path}.xml",   :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'edit',    :format => 'xml'), :path => formatted_edit_path, :method => :get)
-      assert_recognizes(options[:options].merge(:action => 'create',  :format => 'xml'), :path => "#{full_path}.xml",  :method => :post)
-      assert_recognizes(options[:options].merge(:action => 'update',  :format => 'xml'), :path => "#{full_path}.xml",  :method => :put)
-      assert_recognizes(options[:options].merge(:action => 'destroy', :format => 'xml'), :path => "#{full_path}.xml",  :method => :delete)
+      assert_recognizes(route_options.merge(:action => 'show',    :format => 'xml'), :path => "#{full_path}.xml",  :method => :get)
+      assert_recognizes(route_options.merge(:action => 'new',     :format => 'xml'), :path => "#{new_path}.xml",   :method => :get)
+      assert_recognizes(route_options.merge(:action => 'edit',    :format => 'xml'), :path => formatted_edit_path, :method => :get)
+      assert_recognizes(route_options.merge(:action => 'create',  :format => 'xml'), :path => "#{full_path}.xml",  :method => :post)
+      assert_recognizes(route_options.merge(:action => 'update',  :format => 'xml'), :path => "#{full_path}.xml",  :method => :put)
+      assert_recognizes(route_options.merge(:action => 'destroy', :format => 'xml'), :path => "#{full_path}.xml",  :method => :delete)
 
-      yield options[:options] if block_given?
+      yield route_options if block_given?
     end
 
     def assert_singleton_named_routes_for(singleton_name, options = {})
-      (options[:options] ||= {})[:controller] ||= singleton_name.to_s.pluralize
-      @controller = "#{options[:options][:controller].camelize}Controller".constantize.new
-      @controller.singleton_class.send(:include, @routes.url_helpers)
-      @request    = ActionController::TestRequest.new
-      @response   = ActionController::TestResponse.new
-      get :show, options[:options]
-      options[:options].delete :action
+      route_options = (options[:options] ||= {}).dup
+      controller_name = route_options[:controller] || options[:controller] || singleton_name.to_s.pluralize
+      @controller = "#{controller_name.camelize}Controller".constantize.new
+      @controller.singleton_class.include(@routes.url_helpers)
+      get :show, params: route_options
+      route_options.delete :action
 
       full_path = "/#{options[:path_prefix]}#{options[:as] || singleton_name}"
       name_prefix = options[:name_prefix]
 
-      assert_named_route "#{full_path}",          "#{name_prefix}#{singleton_name}_path",                options[:options]
-      assert_named_route "#{full_path}.xml",      "#{name_prefix}#{singleton_name}_path",      options[:options].merge(:format => 'xml')
+      assert_named_route "#{full_path}",          "#{name_prefix}#{singleton_name}_path",                route_options
+      assert_named_route "#{full_path}.xml",      "#{name_prefix}#{singleton_name}_path",      route_options.merge(:format => 'xml')
 
-      assert_named_route "#{full_path}/new",      "new_#{name_prefix}#{singleton_name}_path",            options[:options]
-      assert_named_route "#{full_path}/new.xml",  "new_#{name_prefix}#{singleton_name}_path",  options[:options].merge(:format => 'xml')
-      assert_named_route "#{full_path}/edit",     "edit_#{name_prefix}#{singleton_name}_path",           options[:options]
-      assert_named_route "#{full_path}/edit.xml", "edit_#{name_prefix}#{singleton_name}_path", options[:options].merge(:format => 'xml')
+      assert_named_route "#{full_path}/new",      "new_#{name_prefix}#{singleton_name}_path",            route_options
+      assert_named_route "#{full_path}/new.xml",  "new_#{name_prefix}#{singleton_name}_path",  route_options.merge(:format => 'xml')
+      assert_named_route "#{full_path}/edit",     "edit_#{name_prefix}#{singleton_name}_path",           route_options
+      assert_named_route "#{full_path}/edit.xml", "edit_#{name_prefix}#{singleton_name}_path", route_options.merge(:format => 'xml')
     end
 
     def assert_named_route(expected, route, options)
diff --git a/actionpack/test/controller/routing_test.rb b/actionpack/test/controller/routing_test.rb
index 9caa5cbe57..4a2b02a003 100644
--- a/actionpack/test/controller/routing_test.rb
+++ b/actionpack/test/controller/routing_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'controller/fake_controllers'
 require 'active_support/core_ext/object/with_options'
@@ -9,8 +8,6 @@ class MilestonesController < ActionController::Base
   alias_method :show, :index
 end
 
-ROUTING = ActionDispatch::Routing
-
 # See RFC 3986, section 3.3 for allowed path characters.
 class UriReservedCharactersRoutingTest < ActiveSupport::TestCase
   include RoutingTestHelpers
@@ -330,17 +327,23 @@ class LegacyRouteSetTests < ActiveSupport::TestCase
     assert_equal '/stuff', controller.url_for({ :controller => '/stuff', :only_path => true })
   end
 
-  def test_ignores_leading_slash
-    rs.clear!
-    rs.draw { get '/:controller(/:action(/:id))'}
-    test_default_setup
-  end
-
   def test_route_with_colon_first
     rs.draw do
-      get '/:controller/:action/:id', :action => 'index', :id => nil
-      get ':url', :controller => 'tiny_url', :action => 'translate'
+      get '/:controller/:action/:id', action: 'index', id: nil
+      get ':url', controller: 'content', action: 'translate'
     end
+
+    assert_equal({controller: 'content', action: 'translate', url: 'example'}, rs.recognize_path('/example'))
+  end
+
+  def test_route_with_regexp_for_action
+    rs.draw { get '/:controller/:action', action: /auth[-|_].+/ }
+
+    assert_equal({ action: 'auth_google', controller: 'content' }, rs.recognize_path('/content/auth_google'))
+    assert_equal({ action: 'auth-facebook', controller: 'content' }, rs.recognize_path('/content/auth-facebook'))
+
+    assert_equal '/content/auth_google', url_for(rs, { controller: "content", action: "auth_google" })
+    assert_equal '/content/auth-facebook', url_for(rs, { controller: "content", action: "auth-facebook" })
   end
 
   def test_route_with_regexp_for_controller
@@ -872,7 +875,7 @@ class RouteSetTest < ActiveSupport::TestCase
 
   def default_route_set
     @default_route_set ||= begin
-      set = ROUTING::RouteSet.new
+      set = ActionDispatch::Routing::RouteSet.new
       set.draw do
         get '/:controller(/:action(/:id))'
       end
@@ -1749,40 +1752,10 @@ class RouteSetTest < ActiveSupport::TestCase
 
   include ActionDispatch::RoutingVerbs
 
-  class TestSet < ROUTING::RouteSet
-    def initialize(block)
-      @block = block
-      super()
-    end
-
-    class Dispatcher < ROUTING::RouteSet::Dispatcher
-      def initialize(defaults, set, block)
-        super(defaults)
-        @block = block
-        @set = set
-      end
-
-      def controller_reference(controller_param)
-        block = @block
-        set = @set
-        Class.new(ActionController::Base) {
-          include set.url_helpers
-          define_method(:process) { |name| block.call(self) }
-          def to_a; [200, {}, []]; end
-        }
-      end
-    end
-
-    def dispatcher defaults
-      TestSet::Dispatcher.new defaults, self, @block
-    end
-  end
-
   alias :routes :set
 
   def test_generate_with_optional_params_recalls_last_request
-    controller = nil
-    @set = TestSet.new ->(c) { controller = c }
+    @set = make_set false
 
     set.draw do
       get "blog/", :controller => "blog", :action => "index"
diff --git a/actionpack/test/controller/send_file_test.rb b/actionpack/test/controller/send_file_test.rb
index c002cf4d8f..2820425c31 100644
--- a/actionpack/test/controller/send_file_test.rb
+++ b/actionpack/test/controller/send_file_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 module TestFileUtils
@@ -21,6 +20,47 @@ class SendFileController < ActionController::Base
     send_file(file_path, options)
   end
 
+  def test_send_file_headers_bang
+    options = {
+      :type => Mime[:png],
+      :disposition => 'disposition',
+      :filename => 'filename'
+    }
+
+    send_data "foo", options
+  end
+
+  def test_send_file_headers_with_disposition_as_a_symbol
+    options = {
+      :type => Mime[:png],
+      :disposition => :disposition,
+      :filename => 'filename'
+    }
+
+    send_data "foo", options
+  end
+
+  def test_send_file_headers_with_mime_lookup_with_symbol
+    options = { :type => :png }
+
+    send_data "foo", options
+  end
+
+  def test_send_file_headers_with_bad_symbol
+    options = { :type => :this_type_is_not_registered }
+    send_data "foo", options
+  end
+
+  def test_send_file_headers_with_nil_content_type
+    options = { :type => nil }
+    send_data "foo", options
+  end
+
+  def test_send_file_headers_guess_type_from_extension
+    options = { :filename => params[:filename] }
+    send_data "foo", options
+  end
+
   def data
     send_data(file_data, options)
   end
@@ -35,8 +75,6 @@ class SendFileTest < ActionController::TestCase
 
   def setup
     @controller = SendFileController.new
-    @request = ActionController::TestRequest.new
-    @response = ActionController::TestResponse.new
   end
 
   def test_file_nostream
@@ -91,62 +129,39 @@ class SendFileTest < ActionController::TestCase
 
   # Test that send_file_headers! is setting the correct HTTP headers.
   def test_send_file_headers_bang
-    options = {
-      :type => Mime::PNG,
-      :disposition => 'disposition',
-      :filename => 'filename'
-    }
-
     # Do it a few times: the resulting headers should be identical
     # no matter how many times you send with the same options.
     # Test resolving Ticket #458.
-    @controller.headers = {}
-    @controller.send(:send_file_headers!, options)
-    @controller.send(:send_file_headers!, options)
-    @controller.send(:send_file_headers!, options)
+    5.times do
+      get :test_send_file_headers_bang
 
-    h = @controller.headers
-    assert_equal 'image/png', @controller.content_type
-    assert_equal 'disposition; filename="filename"', h['Content-Disposition']
-    assert_equal 'binary', h['Content-Transfer-Encoding']
-
-    # test overriding Cache-Control: no-cache header to fix IE open/save dialog
-    @controller.send(:send_file_headers!, options)
-    @controller.response.prepare!
-    assert_equal 'private', h['Cache-Control']
+      assert_equal 'image/png', response.content_type
+      assert_equal 'disposition; filename="filename"', response.get_header('Content-Disposition')
+      assert_equal 'binary', response.get_header('Content-Transfer-Encoding')
+      assert_equal 'private', response.get_header('Cache-Control')
+    end
   end
 
   def test_send_file_headers_with_disposition_as_a_symbol
-    options = {
-      :type => Mime::PNG,
-      :disposition => :disposition,
-      :filename => 'filename'
-    }
+    get :test_send_file_headers_with_disposition_as_a_symbol
 
-    @controller.headers = {}
-    @controller.send(:send_file_headers!, options)
-    assert_equal 'disposition; filename="filename"', @controller.headers['Content-Disposition']
+    assert_equal 'disposition; filename="filename"', response.get_header('Content-Disposition')
   end
 
   def test_send_file_headers_with_mime_lookup_with_symbol
-    options = {
-      :type => :png
-    }
-
-    @controller.headers = {}
-    @controller.send(:send_file_headers!, options)
-
-    assert_equal 'image/png', @controller.content_type
+    get __method__
+    assert_equal 'image/png', response.content_type
   end
 
 
   def test_send_file_headers_with_bad_symbol
-    options = {
-      :type => :this_type_is_not_registered
-    }
+    error = assert_raise(ArgumentError) { get __method__ }
+    assert_equal "Unknown MIME type this_type_is_not_registered", error.message
+  end
 
-    @controller.headers = {}
-    assert_raise(ArgumentError) { @controller.send(:send_file_headers!, options) }
+  def test_send_file_headers_with_nil_content_type
+    error = assert_raise(ArgumentError) { get __method__ }
+    assert_equal ":type option required", error.message
   end
 
   def test_send_file_headers_guess_type_from_extension
@@ -161,10 +176,8 @@ class SendFileTest < ActionController::TestCase
       'file.unk' => 'application/octet-stream',
       'zip' => 'application/octet-stream'
     }.each do |filename,expected_type|
-      options = { :filename => filename }
-      @controller.headers = {}
-      @controller.send(:send_file_headers!, options)
-      assert_equal expected_type, @controller.content_type
+      get __method__, params: { filename: filename }
+      assert_equal expected_type, response.content_type
     end
   end
 
@@ -182,7 +195,7 @@ class SendFileTest < ActionController::TestCase
   %w(file data).each do |method|
     define_method "test_send_#{method}_status" do
       @controller.options = { :stream => false, :status => 500 }
-      assert_nothing_raised { assert_not_nil process(method) }
+      assert_not_nil process(method)
       assert_equal 500, @response.status
     end
 
diff --git a/actionpack/test/controller/show_exceptions_test.rb b/actionpack/test/controller/show_exceptions_test.rb
index f7eba1ef43..786dc15444 100644
--- a/actionpack/test/controller/show_exceptions_test.rb
+++ b/actionpack/test/controller/show_exceptions_test.rb
@@ -58,13 +58,13 @@ module ShowExceptions
   class ShowExceptionsOverriddenTest < ActionDispatch::IntegrationTest
     test 'show error page' do
       @app = ShowExceptionsOverriddenController.action(:boom)
-      get '/', {'detailed' => '0'}
+      get '/', params: { 'detailed' => '0' }
       assert_equal "500 error fixture\n", body
     end
 
     test 'show diagnostics message' do
       @app = ShowExceptionsOverriddenController.action(:boom)
-      get '/', {'detailed' => '1'}
+      get '/', params: { 'detailed' => '1' }
       assert_match(/boom/, body)
     end
   end
@@ -72,23 +72,23 @@ module ShowExceptions
   class ShowExceptionsFormatsTest < ActionDispatch::IntegrationTest
     def test_render_json_exception
       @app = ShowExceptionsOverriddenController.action(:boom)
-      get "/", {}, 'HTTP_ACCEPT' => 'application/json'
+      get "/", headers: { 'HTTP_ACCEPT' => 'application/json' }
       assert_response :internal_server_error
       assert_equal 'application/json', response.content_type.to_s
-      assert_equal({ :status => '500', :error => 'Internal Server Error' }.to_json, response.body)
+      assert_equal({ :status => 500, :error => 'Internal Server Error' }.to_json, response.body)
     end
 
     def test_render_xml_exception
       @app = ShowExceptionsOverriddenController.action(:boom)
-      get "/", {}, 'HTTP_ACCEPT' => 'application/xml'
+      get "/", headers: { 'HTTP_ACCEPT' => 'application/xml' }
       assert_response :internal_server_error
       assert_equal 'application/xml', response.content_type.to_s
-      assert_equal({ :status => '500', :error => 'Internal Server Error' }.to_xml, response.body)
+      assert_equal({ :status => 500, :error => 'Internal Server Error' }.to_xml, response.body)
     end
 
     def test_render_fallback_exception
       @app = ShowExceptionsOverriddenController.action(:boom)
-      get "/", {}, 'HTTP_ACCEPT' => 'text/csv'
+      get "/", headers: { 'HTTP_ACCEPT' => 'text/csv' }
       assert_response :internal_server_error
       assert_equal 'text/html', response.content_type.to_s
     end
@@ -101,7 +101,7 @@ module ShowExceptions
       @app.instance_variable_set(:@exceptions_app, nil)
       $stderr = StringIO.new
 
-      get '/', {}, 'HTTP_ACCEPT' => 'text/json'
+      get '/', headers: { 'HTTP_ACCEPT' => 'text/json' }
       assert_response :internal_server_error
       assert_equal 'text/plain', response.content_type.to_s
     ensure
diff --git a/actionpack/test/controller/test_case_test.rb b/actionpack/test/controller/test_case_test.rb
index 2e1f21c645..f1a296682d 100644
--- a/actionpack/test/controller/test_case_test.rb
+++ b/actionpack/test/controller/test_case_test.rb
@@ -4,67 +4,82 @@ require 'active_support/json/decoding'
 require 'rails/engine'
 
 class TestCaseTest < ActionController::TestCase
+  def self.fixture_path; end;
+
   class TestController < ActionController::Base
     def no_op
-      render :text => 'dummy'
+      render plain: 'dummy'
     end
 
     def set_flash
       flash["test"] = ">#{flash["test"]}<"
-      render :text => 'ignore me'
+      render plain: 'ignore me'
+    end
+
+    def delete_flash
+      flash.delete("test")
+      render plain: 'ignore me'
     end
 
     def set_flash_now
       flash.now["test_now"] = ">#{flash["test_now"]}<"
-      render :text => 'ignore me'
+      render plain: 'ignore me'
     end
 
     def set_session
       session['string'] = 'A wonder'
       session[:symbol] = 'it works'
-      render :text => 'Success'
+      render plain: 'Success'
     end
 
     def reset_the_session
       reset_session
-      render :text => 'ignore me'
+      render plain: 'ignore me'
     end
 
     def render_raw_post
       raise ActiveSupport::TestCase::Assertion, "#raw_post is blank" if request.raw_post.blank?
-      render :text => request.raw_post
+      render plain: request.raw_post
     end
 
     def render_body
-      render :text => request.body.read
+      render plain: request.body.read
     end
 
     def test_params
-      render :text => params.inspect
+      render plain: ::JSON.dump(params.to_unsafe_h)
+    end
+
+    def test_query_parameters
+      render plain: ::JSON.dump(request.query_parameters)
+    end
+
+    def test_request_parameters
+      render plain: request.request_parameters.inspect
     end
 
     def test_uri
-      render :text => request.fullpath
+      render plain: request.fullpath
     end
 
     def test_format
-      render :text => request.format
+      render plain: request.format
     end
 
     def test_query_string
-      render :text => request.query_string
+      render plain: request.query_string
     end
 
     def test_protocol
-      render :text => request.protocol
+      render plain: request.protocol
     end
 
     def test_headers
-      render text: request.headers.env.to_json
+      render plain: request.headers.env.to_json
     end
 
     def test_html_output
-      render :text => <<HTML
+      render plain: <<HTML
 <html>
   <body>
     <a href="/"><img src="/images/button.png" /></a>
@@ -86,7 +101,7 @@ HTML
 
     def test_xml_output
       response.content_type = "application/xml"
-      render :text => <<XML
+      render plain: <<XML
 <?xml version="1.0" encoding="UTF-8"?>
 <root>
   <area>area is an empty tag in HTML, raising an error if not in xml mode</area>
@@ -95,15 +110,15 @@ XML
     end
 
     def test_only_one_param
-      render :text => (params[:left] && params[:right]) ? "EEP, Both here!" : "OK"
+      render plain: (params[:left] && params[:right]) ? "EEP, Both here!" : "OK"
     end
 
     def test_remote_addr
-      render :text => (request.remote_addr || "not specified")
+      render plain: (request.remote_addr || "not specified")
     end
 
     def test_file_upload
-      render :text => params[:file].size
+      render plain: params[:file].size
     end
 
     def test_send_file
@@ -111,26 +126,20 @@ XML
     end
 
     def redirect_to_same_controller
-      redirect_to :controller => 'test', :action => 'test_uri', :id => 5
+      redirect_to controller: 'test', action: 'test_uri', id: 5
     end
 
     def redirect_to_different_controller
-      redirect_to :controller => 'fail', :id => 5
+      redirect_to controller: 'fail', id: 5
     end
 
     def create
-      head :created, :location => 'created resource'
+      head :created, location: 'created resource'
     end
 
     def delete_cookie
       cookies.delete("foo")
-      render :nothing => true
-    end
-
-    def test_assigns
-      @foo = "foo"
-      @foo_hash = {:foo => :bar}
-      render :nothing => true
+      render plain: 'ok'
     end
 
     def test_without_body
@@ -144,16 +153,14 @@ XML
     private
 
       def generate_url(opts)
-        url_for(opts.merge(:action => "test_uri"))
+        url_for(opts.merge(action: "test_uri"))
       end
   end
 
   def setup
     super
     @controller = TestController.new
-    @request    = ActionController::TestRequest.new
-    @response   = ActionController::TestResponse.new
-    @request.env['PATH_INFO'] = nil
+    @request.delete_header 'PATH_INFO'
     @routes = ActionDispatch::Routing::RouteSet.new.tap do |r|
       r.draw do
         get ':controller(/:action(/:id))'
@@ -161,22 +168,11 @@ XML
     end
   end
 
-  class ViewAssignsController < ActionController::Base
-    def test_assigns
-      @foo = "foo"
-      render :nothing => true
-    end
-
-    def view_assigns
-      { "bar" => "bar" }
-    end
-  end
-
   class DefaultUrlOptionsCachingController < ActionController::Base
     before_action { @dynamic_opt = 'opt' }
 
     def test_url_options_reset
-      render text: url_for(params)
+      render plain: url_for(params)
     end
 
     def default_url_options
@@ -209,32 +205,50 @@ XML
   end
 
   def test_raw_post_handling
-    params = Hash[:page, {:name => 'page name'}, 'some key', 123]
-    post :render_raw_post, params.dup
+    params = Hash[:page, { name: 'page name' }, 'some key', 123]
+    post :render_raw_post, params: params.dup
 
     assert_equal params.to_query, @response.body
   end
 
   def test_body_stream
-    params = Hash[:page, { :name => 'page name' }, 'some key', 123]
+    params = Hash[:page, { name: 'page name' }, 'some key', 123]
+
+    post :render_body, params: params.dup
+
+    assert_equal params.to_query, @response.body
+  end
+
+  def test_deprecated_body_stream
+    params = Hash[:page, { name: 'page name' }, 'some key', 123]
 
-    post :render_body, params.dup
+    assert_deprecated { post :render_body, params.dup }
 
     assert_equal params.to_query, @response.body
   end
 
   def test_document_body_and_params_with_post
-    post :test_params, :id => 1
-    assert_equal("{\"id\"=>\"1\", \"controller\"=>\"test_case_test/test\", \"action\"=>\"test_params\"}", @response.body)
+    post :test_params, params: { id: 1 }
+    assert_equal({"id"=>"1", "controller"=>"test_case_test/test", "action"=>"test_params"}, ::JSON.parse(@response.body))
   end
 
   def test_document_body_with_post
-    post :render_body, "document body"
+    post :render_body, body: "document body"
+    assert_equal "document body", @response.body
+  end
+
+  def test_deprecated_document_body_with_post
+    assert_deprecated { post :render_body, "document body" }
     assert_equal "document body", @response.body
   end
 
   def test_document_body_with_put
-    put :render_body, "document body"
+    put :render_body, body: "document body"
+    assert_equal "document body", @response.body
+  end
+
+  def test_deprecated_document_body_with_put
+    assert_deprecated { put :render_body, "document body" }
     assert_equal "document body", @response.body
   end
 
@@ -243,25 +257,42 @@ XML
     assert_equal 200, @response.status
   end
 
-  def test_head_params_as_string
-    assert_raise(NoMethodError) { head :test_params, "document body", :id => 10 }
-  end
-
   def test_process_without_flash
     process :set_flash
     assert_equal '><', flash['test']
   end
 
+  def test_deprecated_process_with_flash
+    assert_deprecated { process :set_flash, "GET", nil, nil, { "test" => "value" } }
+    assert_equal '>value<', flash['test']
+  end
+
   def test_process_with_flash
-    process :set_flash, "GET", nil, nil, { "test" => "value" }
+    process :set_flash,
+      method: "GET",
+      flash: { "test" => "value" }
     assert_equal '>value<', flash['test']
   end
 
+  def test_deprecated_process_with_flash_now
+    assert_deprecated { process :set_flash_now, "GET", nil, nil, { "test_now" => "value_now" } }
+    assert_equal '>value_now<', flash['test_now']
+  end
+
   def test_process_with_flash_now
-    process :set_flash_now, "GET", nil, nil, { "test_now" => "value_now" }
+    process :set_flash_now,
+      method: "GET",
+      flash: { "test_now" => "value_now" }
     assert_equal '>value_now<', flash['test_now']
   end
 
+  def test_process_delete_flash
+    process :set_flash
+    process :delete_flash
+    assert_empty flash
+    assert_empty session
+  end
+
   def test_process_with_session
     process :set_session
     assert_equal 'A wonder', session['string'], "A value stored in the session should be available by string key"
@@ -271,22 +302,48 @@ XML
   end
 
   def test_process_with_session_arg
-    process :no_op, "GET", nil, { 'string' => 'value1', :symbol => 'value2' }
+    assert_deprecated { process :no_op, "GET", nil, { 'string' => 'value1', symbol: 'value2' } }
     assert_equal 'value1', session['string']
     assert_equal 'value1', session[:string]
     assert_equal 'value2', session['symbol']
     assert_equal 'value2', session[:symbol]
   end
 
+  def test_process_with_session_kwarg
+    process :no_op, method: "GET", session: { 'string' => 'value1', symbol: 'value2' }
+    assert_equal 'value1', session['string']
+    assert_equal 'value1', session[:string]
+    assert_equal 'value2', session['symbol']
+    assert_equal 'value2', session[:symbol]
+  end
+
+  def test_deprecated_process_merges_session_arg
+    session[:foo] = 'bar'
+    assert_deprecated {
+      get :no_op, nil, { bar: 'baz' }
+    }
+    assert_equal 'bar', session[:foo]
+    assert_equal 'baz', session[:bar]
+  end
+
   def test_process_merges_session_arg
     session[:foo] = 'bar'
-    get :no_op, nil, { :bar => 'baz' }
+    get :no_op, session: { bar: 'baz' }
     assert_equal 'bar', session[:foo]
     assert_equal 'baz', session[:bar]
   end
 
+  def test_deprecated_merged_session_arg_is_retained_across_requests
+    assert_deprecated {
+      get :no_op, nil, { foo: 'bar' }
+    }
+    assert_equal 'bar', session[:foo]
+    get :no_op
+    assert_equal 'bar', session[:foo]
+  end
+
   def test_merged_session_arg_is_retained_across_requests
-    get :no_op, nil, { :foo => 'bar' }
+    get :no_op, session: { foo: 'bar' }
     assert_equal 'bar', session[:foo]
     get :no_op
     assert_equal 'bar', session[:foo]
@@ -294,7 +351,7 @@ XML
 
   def test_process_overwrites_existing_session_arg
     session[:foo] = 'bar'
-    get :no_op, nil, { :foo => 'baz' }
+    get :no_op, session: { foo: 'baz' }
     assert_equal 'baz', session[:foo]
   end
 
@@ -321,19 +378,40 @@ XML
     assert_equal "/test_case_test/test/test_uri", @response.body
   end
 
+  def test_process_with_symbol_method
+    process :test_uri, method: :get
+    assert_equal "/test_case_test/test/test_uri", @response.body
+  end
+
+  def test_deprecated_process_with_request_uri_with_params
+    assert_deprecated { process :test_uri, "GET", id: 7 }
+    assert_equal "/test_case_test/test/test_uri/7", @response.body
+  end
+
   def test_process_with_request_uri_with_params
-    process :test_uri, "GET", :id => 7
+    process :test_uri,
+      method: "GET",
+      params: { id: 7 }
+
     assert_equal "/test_case_test/test/test_uri/7", @response.body
   end
 
+  def test_deprecated_process_with_request_uri_with_params_with_explicit_uri
+    @request.env['PATH_INFO'] = "/explicit/uri"
+    assert_deprecated { process :test_uri, "GET", id: 7 }
+    assert_equal "/explicit/uri", @response.body
+  end
+
   def test_process_with_request_uri_with_params_with_explicit_uri
     @request.env['PATH_INFO'] = "/explicit/uri"
-    process :test_uri, "GET", :id => 7
+    process :test_uri, method: "GET", params: { id: 7 }
     assert_equal "/explicit/uri", @response.body
   end
 
   def test_process_with_query_string
-    process :test_query_string, "GET", :q => 'test'
+    process :test_query_string,
+      method: "GET",
+      params: { q: 'test' }
     assert_equal "q=test", @response.body
   end
 
@@ -345,36 +423,12 @@ XML
   end
 
   def test_multiple_calls
-    process :test_only_one_param, "GET", :left => true
+    process :test_only_one_param, method: "GET", params: { left: true }
     assert_equal "OK", @response.body
-    process :test_only_one_param, "GET", :right => true
+    process :test_only_one_param, method: "GET", params: { right: true }
     assert_equal "OK", @response.body
   end
 
-  def test_assigns
-    process :test_assigns
-    # assigns can be accessed using assigns(key)
-    # or assigns[key], where key is a string or
-    # a symbol
-    assert_equal "foo", assigns(:foo)
-    assert_equal "foo", assigns("foo")
-    assert_equal "foo", assigns[:foo]
-    assert_equal "foo", assigns["foo"]
-
-    # but the assigned variable should not have its own keys stringified
-    expected_hash = { :foo => :bar }
-    assert_equal expected_hash, assigns(:foo_hash)
-  end
-
-  def test_view_assigns
-    @controller = ViewAssignsController.new
-    process :test_assigns
-    assert_equal nil, assigns(:foo)
-    assert_equal nil, assigns[:foo]
-    assert_equal "bar", assigns(:bar)
-    assert_equal "bar", assigns[:bar]
-  end
-
   def test_should_not_impose_childless_html_tags_in_xml
     process :test_xml_output
 
@@ -390,21 +444,21 @@ XML
   end
 
   def test_assert_generates
-    assert_generates 'controller/action/5', :controller => 'controller', :action => 'action', :id => '5'
-    assert_generates 'controller/action/7', {:id => "7"}, {:controller => "controller", :action => "action"}
-    assert_generates 'controller/action/5', {:controller => "controller", :action => "action", :id => "5", :name => "bob"}, {}, {:name => "bob"}
-    assert_generates 'controller/action/7', {:id => "7", :name => "bob"}, {:controller => "controller", :action => "action"}, {:name => "bob"}
-    assert_generates 'controller/action/7', {:id => "7"}, {:controller => "controller", :action => "action", :name => "bob"}, {}
+    assert_generates 'controller/action/5', controller: 'controller', action: 'action', id: '5'
+    assert_generates 'controller/action/7', { id: "7" }, { controller: "controller", action: "action" }
+    assert_generates 'controller/action/5', { controller: "controller", action: "action", id: "5", name: "bob" }, {}, { name: "bob" }
+    assert_generates 'controller/action/7', { id: "7", name: "bob" }, { controller: "controller", action: "action" }, { name: "bob" }
+    assert_generates 'controller/action/7', { id: "7" }, { controller: "controller", action: "action", name: "bob" }, {}
   end
 
   def test_assert_routing
-    assert_routing 'content', :controller => 'content', :action => 'index'
+    assert_routing 'content', controller: 'content', action: 'index'
   end
 
   def test_assert_routing_with_method
     with_routing do |set|
       set.draw { resources(:content) }
-      assert_routing({ :method => 'post', :path => 'content' }, { :controller => 'content', :action => 'create' })
+      assert_routing({ method: 'post', path: 'content' }, { controller: 'content', action: 'create' })
     end
   end
 
@@ -416,30 +470,88 @@ XML
         end
       end
 
-      assert_routing 'admin/user', :controller => 'admin/user', :action => 'index'
+      assert_routing 'admin/user', controller: 'admin/user', action: 'index'
     end
   end
 
   def test_assert_routing_with_glob
     with_routing do |set|
       set.draw { get('*path' => "pages#show") }
-      assert_routing('/company/about', { :controller => 'pages', :action => 'show', :path => 'company/about' })
+      assert_routing('/company/about', { controller: 'pages', action: 'show', path: 'company/about' })
     end
   end
 
+  def test_deprecated_params_passing
+    assert_deprecated {
+      get :test_params, page: { name: "Page name", month: '4', year: '2004', day: '6' }
+    }
+    parsed_params = ::JSON.parse(@response.body)
+    assert_equal(
+      {
+        'controller' => 'test_case_test/test', 'action' => 'test_params',
+        'page' => { 'name' => "Page name", 'month' => '4', 'year' => '2004', 'day' => '6' }
+      },
+      parsed_params
+    )
+  end
+
   def test_params_passing
-    get :test_params, :page => {:name => "Page name", :month => '4', :year => '2004', :day => '6'}
+    get :test_params, params: {
+      page: {
+        name: "Page name",
+        month: '4',
+        year: '2004',
+        day: '6'
+      }
+    }
+    parsed_params = ::JSON.parse(@response.body)
+    assert_equal(
+      {
+        'controller' => 'test_case_test/test', 'action' => 'test_params',
+        'page' => { 'name' => "Page name", 'month' => '4', 'year' => '2004', 'day' => '6' }
+      },
+      parsed_params
+    )
+  end
+
+  def test_query_param_named_action
+    get :test_query_parameters, params: {action: 'foobar'}
+    parsed_params = JSON.parse(@response.body)
+    assert_equal({'action' => 'foobar'}, parsed_params)
+  end
+
+  def test_request_param_named_action
+    post :test_request_parameters, params: {action: 'foobar'}
     parsed_params = eval(@response.body)
+    assert_equal({'action' => 'foobar'}, parsed_params)
+  end
+
+  def test_kwarg_params_passing_with_session_and_flash
+    get :test_params, params: {
+      page: {
+        name: "Page name",
+        month: '4',
+        year: '2004',
+        day: '6'
+      }
+    }, session: { 'foo' => 'bar' }, flash: { notice: 'created' }
+
+    parsed_params = ::JSON.parse(@response.body)
     assert_equal(
       {'controller' => 'test_case_test/test', 'action' => 'test_params',
        'page' => {'name' => "Page name", 'month' => '4', 'year' => '2004', 'day' => '6'}},
       parsed_params
     )
+
+    assert_equal 'bar', session[:foo]
+    assert_equal 'created', flash[:notice]
   end
 
   def test_params_passing_with_fixnums
-    get :test_params, :page => {:name => "Page name", :month => 4, :year => 2004, :day => 6}
-    parsed_params = eval(@response.body)
+    get :test_params, params: {
+      page: { name: "Page name", month: 4, year: 2004, day: 6 }
+    }
+    parsed_params = ::JSON.parse(@response.body)
     assert_equal(
       {'controller' => 'test_case_test/test', 'action' => 'test_params',
        'page' => {'name' => "Page name", 'month' => '4', 'year' => '2004', 'day' => '6'}},
@@ -448,18 +560,28 @@ XML
   end
 
   def test_params_passing_with_fixnums_when_not_html_request
-    get :test_params, :format => 'json', :count => 999
-    parsed_params = eval(@response.body)
+    get :test_params, params: { format: 'json', count: 999 }
+    parsed_params = ::JSON.parse(@response.body)
     assert_equal(
       {'controller' => 'test_case_test/test', 'action' => 'test_params',
-       'format' => 'json', 'count' => 999 },
+       'format' => 'json', 'count' => '999' },
       parsed_params
     )
   end
 
   def test_params_passing_path_parameter_is_string_when_not_html_request
-    get :test_params, :format => 'json', :id => 1
-    parsed_params = eval(@response.body)
+    get :test_params, params: { format: 'json', id: 1 }
+    parsed_params = ::JSON.parse(@response.body)
+    assert_equal(
+      {'controller' => 'test_case_test/test', 'action' => 'test_params',
+       'format' => 'json', 'id' => '1' },
+      parsed_params
+    )
+  end
+
+  def test_deprecated_params_passing_path_parameter_is_string_when_not_html_request
+    assert_deprecated { get :test_params, format: 'json', id: 1 }
+    parsed_params = ::JSON.parse(@response.body)
     assert_equal(
       {'controller' => 'test_case_test/test', 'action' => 'test_params',
        'format' => 'json', 'id' => '1' },
@@ -469,9 +591,11 @@ XML
 
   def test_params_passing_with_frozen_values
     assert_nothing_raised do
-      get :test_params, :frozen => 'icy'.freeze, :frozens => ['icy'.freeze].freeze, :deepfreeze => { :frozen => 'icy'.freeze }.freeze
+      get :test_params, params: {
+        frozen: 'icy'.freeze, frozens: ['icy'.freeze].freeze, deepfreeze: { frozen: 'icy'.freeze }.freeze
+      }
     end
-    parsed_params = eval(@response.body)
+    parsed_params = ::JSON.parse(@response.body)
     assert_equal(
       {'controller' => 'test_case_test/test', 'action' => 'test_params',
        'frozen' => 'icy', 'frozens' => ['icy'], 'deepfreeze' => { 'frozen' => 'icy' }},
@@ -480,8 +604,8 @@ XML
   end
 
   def test_params_passing_doesnt_modify_in_place
-    page = {:name => "Page name", :month => 4, :year => 2004, :day => 6}
-    get :test_params, :page => page
+    page = { name: "Page name", month: 4, year: 2004, day: 6 }
+    get :test_params, params: { page: page }
     assert_equal 2004, page[:year]
   end
 
@@ -503,26 +627,58 @@ XML
     assert_equal "application/json", parsed_env["CONTENT_TYPE"]
   end
 
+  def test_mutating_content_type_headers_for_plain_text_files_sets_the_header
+    @request.headers['Content-Type'] = 'text/plain'
+    post :render_body, params: { name: 'foo.txt' }
+
+    assert_equal 'text/plain', @request.headers['Content-type']
+    assert_equal 'foo.txt', @request.request_parameters[:name]
+    assert_equal 'render_body', @request.path_parameters[:action]
+  end
+
+  def test_mutating_content_type_headers_for_html_files_sets_the_header
+    @request.headers['Content-Type'] = 'text/html'
+    post :render_body, params: { name: 'foo.html' }
+
+    assert_equal 'text/html', @request.headers['Content-type']
+    assert_equal 'foo.html', @request.request_parameters[:name]
+    assert_equal 'render_body', @request.path_parameters[:action]
+  end
+
+  def test_mutating_content_type_headers_for_non_registered_mime_type_raises_an_error
+    assert_raises(RuntimeError) do
+      @request.headers['Content-Type'] = 'type/fake'
+      post :render_body, params: { name: 'foo.fake' }
+    end
+  end
+
   def test_id_converted_to_string
-    get :test_params, :id => 20, :foo => Object.new
+    get :test_params, params: {
+      id: 20, foo: Object.new
+    }
+    assert_kind_of String, @request.path_parameters[:id]
+  end
+
+  def test_deprecared_id_converted_to_string
+    assert_deprecated { get :test_params, id: 20, foo: Object.new}
     assert_kind_of String, @request.path_parameters[:id]
   end
 
   def test_array_path_parameter_handled_properly
     with_routing do |set|
       set.draw do
-        get 'file/*path', :to => 'test_case_test/test#test_params'
+        get 'file/*path', to: 'test_case_test/test#test_params'
         get ':controller/:action'
       end
 
-      get :test_params, :path => ['hello', 'world']
+      get :test_params, params: { path: ['hello', 'world'] }
       assert_equal ['hello', 'world'], @request.path_parameters[:path]
       assert_equal 'hello/world', @request.path_parameters[:path].to_param
     end
   end
 
   def test_assert_realistic_path_parameters
-    get :test_params, :id => 20, :foo => Object.new
+    get :test_params, params: { id: 20, foo: Object.new }
 
     # All elements of path_parameters should use Symbol keys
     @request.path_parameters.each_key do |key|
@@ -554,19 +710,51 @@ XML
   end
 
   def test_header_properly_reset_after_remote_http_request
-    xhr :get, :test_params
+    get :test_params, xhr: true
     assert_nil @request.env['HTTP_X_REQUESTED_WITH']
     assert_nil @request.env['HTTP_ACCEPT']
   end
 
-  def test_header_properly_reset_after_get_request
-    get :test_params
-    @request.recycle!
-    assert_nil @request.instance_variable_get("@request_method")
+  def test_deprecated_xhr_with_params
+    assert_deprecated { xhr :get, :test_params, params: { id: 1 } }
+
+    assert_equal({"id"=>"1", "controller"=>"test_case_test/test", "action"=>"test_params"}, ::JSON.parse(@response.body))
+  end
+
+  def test_xhr_with_params
+    get :test_params, params: { id: 1 }, xhr: true
+
+    assert_equal({"id"=>"1", "controller"=>"test_case_test/test", "action"=>"test_params"}, ::JSON.parse(@response.body))
+  end
+
+  def test_xhr_with_session
+    get :set_session, xhr: true
+
+    assert_equal 'A wonder', session['string'], "A value stored in the session should be available by string key"
+    assert_equal 'A wonder', session[:string], "Test session hash should allow indifferent access"
+    assert_equal 'it works', session['symbol'], "Test session hash should allow indifferent access"
+    assert_equal 'it works', session[:symbol], "Test session hash should allow indifferent access"
+  end
+
+  def test_deprecated_xhr_with_session
+    assert_deprecated { xhr :get, :set_session }
+
+    assert_equal 'A wonder', session['string'], "A value stored in the session should be available by string key"
+    assert_equal 'A wonder', session[:string], "Test session hash should allow indifferent access"
+    assert_equal 'it works', session['symbol'], "Test session hash should allow indifferent access"
+    assert_equal 'it works', session[:symbol], "Test session hash should allow indifferent access"
+  end
+
+  def test_deprecated_params_reset_between_post_requests
+    assert_deprecated { post :no_op, foo: "bar" }
+    assert_equal "bar", @request.params[:foo]
+
+    post :no_op
+    assert @request.params[:foo].blank?
   end
 
   def test_params_reset_between_post_requests
-    post :no_op, :foo => "bar"
+    post :no_op, params: { foo: "bar" }
     assert_equal "bar", @request.params[:foo]
 
     post :no_op
@@ -574,15 +762,15 @@ XML
   end
 
   def test_filtered_parameters_reset_between_requests
-    get :no_op, :foo => "bar"
+    get :no_op, params: { foo: "bar" }
     assert_equal "bar", @request.filtered_parameters[:foo]
 
-    get :no_op, :foo => "baz"
+    get :no_op, params: { foo: "baz" }
     assert_equal "baz", @request.filtered_parameters[:foo]
   end
 
   def test_path_params_reset_between_request
-    get :test_params, :id => "foo"
+    get :test_params, params: { id: "foo" }
     assert_equal "foo", @request.path_parameters[:id]
 
     get :test_params
@@ -603,19 +791,38 @@ XML
   end
 
   def test_request_format
-    get :test_format, :format => 'html'
+    get :test_format, params: { format: 'html' }
+    assert_equal 'text/html', @response.body
+
+    get :test_format, params: { format: 'json' }
+    assert_equal 'application/json', @response.body
+
+    get :test_format, params: { format: 'xml' }
+    assert_equal 'application/xml', @response.body
+
+    get :test_format
+    assert_equal 'text/html', @response.body
+  end
+
+  def test_request_format_kwarg
+    get :test_format, format: 'html'
     assert_equal 'text/html', @response.body
 
-    get :test_format, :format => 'json'
+    get :test_format, format: 'json'
     assert_equal 'application/json', @response.body
 
-    get :test_format, :format => 'xml'
+    get :test_format, format: 'xml'
     assert_equal 'application/xml', @response.body
 
     get :test_format
     assert_equal 'text/html', @response.body
   end
 
+  def test_request_format_kwarg_overrides_params
+    get :test_format, format: 'json', params: { format: 'html' }
+    assert_equal 'application/json', @response.body
+  end
+
   def test_should_have_knowledge_of_client_side_cookie_state_even_if_they_are_not_set
     cookies['foo'] = 'bar'
     get :no_op
@@ -669,10 +876,10 @@ XML
   end
 
   def test_fixture_path_is_accessed_from_self_instead_of_active_support_test_case
-    TestCaseTest.stubs(:fixture_path).returns(FILES_DIR)
-
-    uploaded_file = fixture_file_upload('/mona_lisa.jpg', 'image/png')
-    assert_equal File.open("#{FILES_DIR}/mona_lisa.jpg", READ_PLAIN).read, uploaded_file.read
+    TestCaseTest.stub :fixture_path, FILES_DIR do
+      uploaded_file = fixture_file_upload('/mona_lisa.jpg', 'image/png')
+      assert_equal File.open("#{FILES_DIR}/mona_lisa.jpg", READ_PLAIN).read, uploaded_file.read
+    end
   end
 
   def test_test_uploaded_file_with_binary
@@ -699,27 +906,46 @@ XML
     assert_equal File.open(path, READ_PLAIN).read, plain_file_upload.read
   end
 
+  def test_fixture_file_upload_should_be_able_access_to_tempfile
+    file = fixture_file_upload(FILES_DIR + "/mona_lisa.jpg", "image/jpg")
+    assert file.respond_to?(:tempfile), "expected tempfile should respond on fixture file object, got nothing"
+  end
+
   def test_fixture_file_upload
-    post :test_file_upload, :file => fixture_file_upload(FILES_DIR + "/mona_lisa.jpg", "image/jpg")
+    post :test_file_upload,
+      params: {
+        file: fixture_file_upload(FILES_DIR + "/mona_lisa.jpg", "image/jpg")
+      }
     assert_equal '159528', @response.body
   end
 
   def test_fixture_file_upload_relative_to_fixture_path
-    TestCaseTest.stubs(:fixture_path).returns(FILES_DIR)
-    uploaded_file = fixture_file_upload("mona_lisa.jpg", "image/jpg")
-    assert_equal File.open("#{FILES_DIR}/mona_lisa.jpg", READ_PLAIN).read, uploaded_file.read
+    TestCaseTest.stub :fixture_path, FILES_DIR do
+      uploaded_file = fixture_file_upload("mona_lisa.jpg", "image/jpg")
+      assert_equal File.open("#{FILES_DIR}/mona_lisa.jpg", READ_PLAIN).read, uploaded_file.read
+    end
   end
 
   def test_fixture_file_upload_ignores_nil_fixture_path
-    TestCaseTest.stubs(:fixture_path).returns(nil)
     uploaded_file = fixture_file_upload("#{FILES_DIR}/mona_lisa.jpg", "image/jpg")
     assert_equal File.open("#{FILES_DIR}/mona_lisa.jpg", READ_PLAIN).read, uploaded_file.read
   end
 
+  def test_deprecated_action_dispatch_uploaded_file_upload
+    filename = 'mona_lisa.jpg'
+    path = "#{FILES_DIR}/#{filename}"
+    assert_deprecated {
+      post :test_file_upload, file: Rack::Test::UploadedFile.new(path, "image/jpg", true)
+    }
+    assert_equal '159528', @response.body
+  end
+
   def test_action_dispatch_uploaded_file_upload
     filename = 'mona_lisa.jpg'
     path = "#{FILES_DIR}/#{filename}"
-    post :test_file_upload, :file => ActionDispatch::Http::UploadedFile.new(:filename => path, :type => "image/jpg", :tempfile => File.open(path))
+    post :test_file_upload, params: {
+      file: Rack::Test::UploadedFile.new(path, "image/jpg", true)
+    }
     assert_equal '159528', @response.body
   end
 
@@ -742,6 +968,60 @@ XML
   end
 end
 
+class ResponseDefaultHeadersTest < ActionController::TestCase
+  class TestController < ActionController::Base
+    def remove_header
+      headers.delete params[:header]
+      head :ok, 'C' => '3'
+    end
+
+    # Render a head response, but don't touch default headers
+    def leave_alone
+      head :ok
+    end
+  end
+
+  def before_setup
+    @original = ActionDispatch::Response.default_headers
+    @defaults = { 'A' => '1', 'B' => '2' }
+    ActionDispatch::Response.default_headers = @defaults
+    super
+  end
+
+  teardown do
+    ActionDispatch::Response.default_headers = @original
+  end
+
+  def setup
+    super
+    @controller = TestController.new
+    @request.env['PATH_INFO'] = nil
+    @routes = ActionDispatch::Routing::RouteSet.new.tap do |r|
+      r.draw do
+        get ':controller(/:action(/:id))'
+      end
+    end
+  end
+
+  test "response contains default headers" do
+    get :leave_alone
+
+    # Response headers start out with the defaults
+    assert_equal @defaults.merge('Content-Type' => 'text/html'), response.headers
+  end
+
+  test "response deletes a default header" do
+    get :remove_header, params: { header: 'A' }
+    assert_response :ok
+
+    # After a request, the response in the test case doesn't have the
+    # defaults merged on top again.
+    assert_not_includes response.headers, 'A'
+    assert_includes response.headers, 'B'
+    assert_includes response.headers, 'C'
+  end
+end
+
 module EngineControllerTests
   class Engine < ::Rails::Engine
     isolate_namespace EngineControllerTests
@@ -753,7 +1033,7 @@ module EngineControllerTests
 
   class BarController < ActionController::Base
     def index
-      render :text => 'bar'
+      render plain: 'bar'
     end
   end
 
@@ -830,7 +1110,7 @@ class NamedRoutesControllerTest < ActionController::TestCase
     with_routing do |set|
       set.draw { resources :contents }
       assert_equal 'http://test.host/contents/new', new_content_url
-      assert_equal 'http://test.host/contents/1', content_url(:id => 1)
+      assert_equal 'http://test.host/contents/1', content_url(id: 1)
     end
   end
 end
@@ -839,7 +1119,7 @@ class AnonymousControllerTest < ActionController::TestCase
   def setup
     @controller = Class.new(ActionController::Base) do
       def index
-        render :text => params[:controller]
+        render plain: params[:controller]
       end
     end.new
 
@@ -860,29 +1140,29 @@ class RoutingDefaultsTest < ActionController::TestCase
   def setup
     @controller = Class.new(ActionController::Base) do
       def post
-        render :text => request.fullpath
+        render plain: request.fullpath
       end
 
       def project
-        render :text => request.fullpath
+        render plain: request.fullpath
       end
     end.new
 
     @routes = ActionDispatch::Routing::RouteSet.new.tap do |r|
       r.draw do
-        get '/posts/:id', :to => 'anonymous#post', :bucket_type => 'post'
-        get '/projects/:id', :to => 'anonymous#project', :defaults => { :bucket_type => 'project' }
+        get '/posts/:id', to: 'anonymous#post', bucket_type: 'post'
+        get '/projects/:id', to: 'anonymous#project', defaults: { bucket_type: 'project' }
       end
     end
   end
 
   def test_route_option_can_be_passed_via_process
-    get :post, :id => 1, :bucket_type => 'post'
+    get :post, params: { id: 1, bucket_type: 'post'}
     assert_equal '/posts/1', @response.body
   end
 
   def test_route_default_is_not_required_for_building_request_uri
-    get :project, :id => 2
+    get :project, params: { id: 2 }
     assert_equal '/projects/2', @response.body
   end
 end
diff --git a/actionpack/test/controller/url_for_integration_test.rb b/actionpack/test/controller/url_for_integration_test.rb
index 24a09222b1..dfc2712e3e 100644
--- a/actionpack/test/controller/url_for_integration_test.rb
+++ b/actionpack/test/controller/url_for_integration_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'controller/fake_controllers'
 require 'active_support/core_ext/object/with_options'
@@ -159,6 +158,7 @@ module ActionPack
 
       ['/posts/ping',[    { :controller => 'posts', :action => 'ping' }]],
       ['/posts/show/1',[  { :controller => 'posts', :action => 'show', :id => '1' }]],
+      ['/posts/show/1',[  { :controller => 'posts', :action => 'show', :id => '1', :format => '' }]],
       ['/posts',[         { :controller => 'posts' }]],
       ['/posts',[         { :controller => 'posts', :action => 'index' }]],
       ['/posts/create',[  { :action => 'create' }, {:day=>nil, :month=>nil, :controller=>"posts", :action=>"show_date"}, '/blog']],
diff --git a/actionpack/test/controller/url_for_test.rb b/actionpack/test/controller/url_for_test.rb
index 0ffa2d2a03..78e883f134 100644
--- a/actionpack/test/controller/url_for_test.rb
+++ b/actionpack/test/controller/url_for_test.rb
@@ -30,8 +30,8 @@ module AbstractController
         assert_equal '/foo/zot', path
       end
 
-      def add_host!
-        W.default_url_options[:host] = 'www.basecamphq.com'
+      def add_host!(app = W)
+        app.default_url_options[:host] = 'www.basecamphq.com'
       end
 
       def add_port!
@@ -255,6 +255,20 @@ module AbstractController
         )
       end
 
+      def test_relative_url_root_is_respected_with_environment_variable
+        # `config.relative_url_root` is set by ENV['RAILS_RELATIVE_URL_ROOT']
+        w = Class.new {
+          config = ActionDispatch::Routing::RouteSet::Config.new '/subdir'
+          r = ActionDispatch::Routing::RouteSet.new(config)
+          r.draw { get ':controller(/:action(/:id(.:format)))' }
+          include r.url_helpers
+        }
+        add_host!(w)
+        assert_equal('https://www.basecamphq.com/subdir/c/a/i',
+          w.new.url_for(:controller => 'c', :action => 'a', :id => 'i', :protocol => 'https')
+        )
+      end
+
       def test_named_routes
         with_routing do |set|
           set.draw do
@@ -437,6 +451,26 @@ module AbstractController
         end
       end
 
+      def test_url_for_with_array_is_unmodified
+        with_routing do |set|
+          set.draw do
+            namespace :admin do
+              resources :posts
+            end
+          end
+
+          kls = Class.new { include set.url_helpers }
+          kls.default_url_options[:host] = 'www.basecamphq.com'
+
+          original_components = [:new, :admin, :post, { param: 'value' }]
+          components = original_components.dup
+
+          kls.new.url_for(components)
+
+          assert_equal(original_components, components)
+        end
+      end
+
       private
         def extract_params(url)
           url.split('?', 2).last.split('&').sort
diff --git a/actionpack/test/controller/url_rewriter_test.rb b/actionpack/test/controller/url_rewriter_test.rb
index d9a1ae7d4f..5f2abc9606 100644
--- a/actionpack/test/controller/url_rewriter_test.rb
+++ b/actionpack/test/controller/url_rewriter_test.rb
@@ -1,7 +1,7 @@
 require 'abstract_unit'
 require 'controller/fake_controllers'
 
-class UrlRewriterTests < ActiveSupport::TestCase
+class UrlRewriterTests < ActionController::TestCase
   class Rewriter
     def initialize(request)
       @options = {
@@ -16,7 +16,6 @@ class UrlRewriterTests < ActiveSupport::TestCase
   end
 
   def setup
-    @request = ActionController::TestRequest.new
     @params = {}
     @rewriter = Rewriter.new(@request) #.new(@request, @params)
     @routes = ActionDispatch::Routing::RouteSet.new.tap do |r|
diff --git a/actionpack/test/controller/webservice_test.rb b/actionpack/test/controller/webservice_test.rb
index 2b109ff19e..6d377c4691 100644
--- a/actionpack/test/controller/webservice_test.rb
+++ b/actionpack/test/controller/webservice_test.rb
@@ -5,16 +5,22 @@ class WebServiceTest < ActionDispatch::IntegrationTest
   class TestController < ActionController::Base
     def assign_parameters
       if params[:full]
-        render :text => dump_params_keys
+        render plain: dump_params_keys
       else
-        render :text => (params.keys - ['controller', 'action']).sort.join(", ")
+        render plain: (params.keys - ['controller', 'action']).sort.join(", ")
       end
     end
 
     def dump_params_keys(hash = params)
       hash.keys.sort.inject("") do |s, k|
         value = hash[k]
-        value = Hash === value ? "(#{dump_params_keys(value)})" : ""
+
+        if value.is_a?(Hash) || value.is_a?(ActionController::Parameters)
+          value = "(#{dump_params_keys(value)})"
+        else
+          value = ""
+        end
+
         s << ", " unless s.empty?
         s << "#{k}#{value}"
       end
@@ -35,7 +41,9 @@ class WebServiceTest < ActionDispatch::IntegrationTest
 
   def test_post_json
     with_test_route_set do
-      post "/", '{"entry":{"summary":"content..."}}', 'CONTENT_TYPE' => 'application/json'
+      post "/",
+        params: '{"entry":{"summary":"content..."}}',
+        headers: { 'CONTENT_TYPE' => 'application/json' }
 
       assert_equal 'entry', @controller.response.body
       assert @controller.params.has_key?(:entry)
@@ -45,7 +53,9 @@ class WebServiceTest < ActionDispatch::IntegrationTest
 
   def test_put_json
     with_test_route_set do
-      put "/", '{"entry":{"summary":"content..."}}', 'CONTENT_TYPE' => 'application/json'
+      put "/",
+        params: '{"entry":{"summary":"content..."}}',
+        headers: { 'CONTENT_TYPE' => 'application/json' }
 
       assert_equal 'entry', @controller.response.body
       assert @controller.params.has_key?(:entry)
@@ -55,9 +65,10 @@ class WebServiceTest < ActionDispatch::IntegrationTest
 
   def test_register_and_use_json_simple
     with_test_route_set do
-      with_params_parsers Mime::JSON => Proc.new { |data| ActiveSupport::JSON.decode(data)['request'].with_indifferent_access } do
-        post "/", '{"request":{"summary":"content...","title":"JSON"}}',
-          'CONTENT_TYPE' => 'application/json'
+      with_params_parsers Mime[:json] => Proc.new { |data| ActiveSupport::JSON.decode(data)['request'].with_indifferent_access } do
+        post "/",
+          params: '{"request":{"summary":"content...","title":"JSON"}}',
+          headers: { 'CONTENT_TYPE' => 'application/json' }
 
         assert_equal 'summary, title', @controller.response.body
         assert @controller.params.has_key?(:summary)
@@ -70,36 +81,44 @@ class WebServiceTest < ActionDispatch::IntegrationTest
 
   def test_use_json_with_empty_request
     with_test_route_set do
-      assert_nothing_raised { post "/", "", 'CONTENT_TYPE' => 'application/json' }
+      assert_nothing_raised { post "/", headers: { 'CONTENT_TYPE' => 'application/json' } }
       assert_equal '', @controller.response.body
     end
   end
 
   def test_dasherized_keys_as_json
     with_test_route_set do
-      post "/?full=1", '{"first-key":{"sub-key":"..."}}', 'CONTENT_TYPE' => 'application/json'
+      post "/?full=1",
+        params: '{"first-key":{"sub-key":"..."}}',
+        headers: { 'CONTENT_TYPE' => 'application/json' }
       assert_equal 'action, controller, first-key(sub-key), full', @controller.response.body
       assert_equal "...", @controller.params['first-key']['sub-key']
     end
   end
 
   def test_parsing_json_doesnot_rescue_exception
-    with_test_route_set do
-      with_params_parsers Mime::JSON => Proc.new { |data| raise Interrupt } do
-        assert_raises(Interrupt) do
-          post "/", '{"title":"JSON"}}', 'CONTENT_TYPE' => 'application/json'
-        end
+    req = Class.new(ActionDispatch::Request) do
+      def params_parsers
+        { Mime[:json] => Proc.new { |data| raise Interrupt } }
       end
+
+      def content_length; get_header('rack.input').length; end
+    end.new({ 'rack.input' => StringIO.new('{"title":"JSON"}}'), 'CONTENT_TYPE' => 'application/json' })
+
+    assert_raises(Interrupt) do
+      req.request_parameters
     end
   end
 
   private
     def with_params_parsers(parsers = {})
       old_session = @integration_session
-      @app = ActionDispatch::ParamsParser.new(app.routes, parsers)
+      original_parsers = ActionDispatch::Request.parameter_parsers
+      ActionDispatch::Request.parameter_parsers = original_parsers.merge parsers
       reset!
       yield
     ensure
+      ActionDispatch::Request.parameter_parsers = original_parsers
       @integration_session = old_session
     end
 
diff --git a/actionpack/test/dispatch/callbacks_test.rb b/actionpack/test/dispatch/callbacks_test.rb
index f767b07e75..5ba76d9ab9 100644
--- a/actionpack/test/dispatch/callbacks_test.rb
+++ b/actionpack/test/dispatch/callbacks_test.rb
@@ -28,7 +28,7 @@ class DispatcherTest < ActiveSupport::TestCase
     assert_equal 4, Foo.a
     assert_equal 4, Foo.b
 
-    dispatch do |env|
+    dispatch do
       raise "error"
     end rescue nil
     assert_equal 6, Foo.a
diff --git a/actionpack/test/dispatch/cookies_test.rb b/actionpack/test/dispatch/cookies_test.rb
index 6223a52a76..84c244c72a 100644
--- a/actionpack/test/dispatch/cookies_test.rb
+++ b/actionpack/test/dispatch/cookies_test.rb
@@ -3,6 +3,75 @@ require 'openssl'
 require 'active_support/key_generator'
 require 'active_support/message_verifier'
 
+class CookieJarTest < ActiveSupport::TestCase
+  attr_reader :request
+
+  def setup
+    @request = ActionDispatch::Request.new({})
+  end
+
+  def test_fetch
+    x = Object.new
+    assert_not request.cookie_jar.key?('zzzzzz')
+    assert_equal x, request.cookie_jar.fetch('zzzzzz', x)
+    assert_not request.cookie_jar.key?('zzzzzz')
+  end
+
+  def test_fetch_exists
+    x = Object.new
+    request.cookie_jar['foo'] = 'bar'
+    assert_equal 'bar', request.cookie_jar.fetch('foo', x)
+  end
+
+  def test_fetch_block
+    x = Object.new
+    assert_not request.cookie_jar.key?('zzzzzz')
+    assert_equal x, request.cookie_jar.fetch('zzzzzz') { x }
+  end
+
+  def test_key_is_to_s
+    request.cookie_jar['foo'] = 'bar'
+    assert_equal 'bar', request.cookie_jar.fetch(:foo)
+  end
+
+  def test_fetch_type_error
+    assert_raises(KeyError) do
+      request.cookie_jar.fetch(:omglolwut)
+    end
+  end
+
+  def test_each
+    request.cookie_jar['foo'] = :bar
+    list = []
+    request.cookie_jar.each do |k,v|
+      list << [k, v]
+    end
+
+    assert_equal [['foo', :bar]], list
+  end
+
+  def test_enumerable
+    request.cookie_jar['foo'] = :bar
+    actual = request.cookie_jar.map { |k,v| [k.to_s, v.to_s] }
+    assert_equal [['foo', 'bar']], actual
+  end
+
+  def test_key_methods
+    assert !request.cookie_jar.key?(:foo)
+    assert !request.cookie_jar.has_key?("foo")
+
+    request.cookie_jar[:foo] = :bar
+    assert request.cookie_jar.key?(:foo)
+    assert request.cookie_jar.has_key?("foo")
+  end
+
+  def test_write_doesnt_set_a_nil_header
+    headers = {}
+    request.cookie_jar.write(headers)
+    assert !headers.include?('Set-Cookie')
+  end
+end
+
 class CookiesTest < ActionController::TestCase
   class CustomSerializer
     def self.load(value)
@@ -14,16 +83,6 @@ class CookiesTest < ActionController::TestCase
     end
   end
 
-  class JSONWrapper
-    def initialize(obj)
-      @obj = obj
-    end
-
-    def as_json(options = nil)
-      "wrapped: #{@obj.as_json(options)}"
-    end
-  end
-
   class TestController < ActionController::Base
     def authenticate
       cookies["user_name"] = "david"
@@ -88,11 +147,6 @@ class CookiesTest < ActionController::TestCase
       head :ok
     end
 
-    def set_wrapped_signed_cookie
-      cookies.signed[:user_id] = JSONWrapper.new(45)
-      head :ok
-    end
-
     def get_signed_cookie
       cookies.signed[:user_id]
       head :ok
@@ -103,6 +157,21 @@ class CookiesTest < ActionController::TestCase
       head :ok
     end
 
+    class JSONWrapper
+      def initialize(obj)
+        @obj = obj
+      end
+
+      def as_json(options = nil)
+        "wrapped: #{@obj.as_json(options)}"
+      end
+    end
+
+    def set_wrapped_signed_cookie
+      cookies.signed[:user_id] = JSONWrapper.new(45)
+      head :ok
+    end
+
     def set_wrapped_encrypted_cookie
       cookies.encrypted[:foo] = JSONWrapper.new('bar')
       head :ok
@@ -207,68 +276,18 @@ class CookiesTest < ActionController::TestCase
 
   tests TestController
 
+  SALT = 'b3c631c314c0bbca50c1b2843150fe33'
+
   def setup
     super
-    @request.env["action_dispatch.key_generator"] = ActiveSupport::KeyGenerator.new("b3c631c314c0bbca50c1b2843150fe33", iterations: 2)
-    @request.env["action_dispatch.signed_cookie_salt"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.encrypted_cookie_salt"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.encrypted_signed_cookie_salt"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.host = "www.nextangle.com"
-  end
-
-  def test_fetch
-    x = Object.new
-    assert_not request.cookie_jar.key?('zzzzzz')
-    assert_equal x, request.cookie_jar.fetch('zzzzzz', x)
-    assert_not request.cookie_jar.key?('zzzzzz')
-  end
-
-  def test_fetch_exists
-    x = Object.new
-    request.cookie_jar['foo'] = 'bar'
-    assert_equal 'bar', request.cookie_jar.fetch('foo', x)
-  end
-
-  def test_fetch_block
-    x = Object.new
-    assert_not request.cookie_jar.key?('zzzzzz')
-    assert_equal x, request.cookie_jar.fetch('zzzzzz') { x }
-  end
-
-  def test_key_is_to_s
-    request.cookie_jar['foo'] = 'bar'
-    assert_equal 'bar', request.cookie_jar.fetch(:foo)
-  end
-
-  def test_fetch_type_error
-    assert_raises(KeyError) do
-      request.cookie_jar.fetch(:omglolwut)
-    end
-  end
 
-  def test_each
-    request.cookie_jar['foo'] = :bar
-    list = []
-    request.cookie_jar.each do |k,v|
-      list << [k, v]
-    end
+    @request.env["action_dispatch.key_generator"] = ActiveSupport::KeyGenerator.new(SALT, iterations: 2)
 
-    assert_equal [['foo', :bar]], list
-  end
+    @request.env["action_dispatch.signed_cookie_salt"] =
+      @request.env["action_dispatch.encrypted_cookie_salt"] =
+      @request.env["action_dispatch.encrypted_signed_cookie_salt"] = SALT
 
-  def test_enumerable
-    request.cookie_jar['foo'] = :bar
-    actual = request.cookie_jar.map { |k,v| [k.to_s, v.to_s] }
-    assert_equal [['foo', 'bar']], actual
-  end
-
-  def test_key_methods
-    assert !request.cookie_jar.key?(:foo)
-    assert !request.cookie_jar.has_key?("foo")
-
-    request.cookie_jar[:foo] = :bar
-    assert request.cookie_jar.key?(:foo)
-    assert request.cookie_jar.has_key?("foo")
+    @request.host = "www.nextangle.com"
   end
 
   def test_setting_cookie
@@ -280,7 +299,7 @@ class CookiesTest < ActionController::TestCase
   def test_setting_the_same_value_to_cookie
     request.cookies[:user_name] = 'david'
     get :authenticate
-    assert response.cookies.empty?
+    assert_predicate response.cookies, :empty?
   end
 
   def test_setting_the_same_value_to_permanent_cookie
@@ -321,10 +340,12 @@ class CookiesTest < ActionController::TestCase
   end
 
   def test_setting_cookie_with_secure_when_always_write_cookie_is_true
-    ActionDispatch::Cookies::CookieJar.any_instance.stubs(:always_write_cookie).returns(true)
+    old_cookie, @request.cookie_jar.always_write_cookie = @request.cookie_jar.always_write_cookie, true
     get :authenticate_with_secure
     assert_cookie_header "user_name=david; path=/; secure"
     assert_equal({"user_name" => "david"}, @response.cookies)
+  ensure
+    @request.cookie_jar.always_write_cookie = old_cookie
   end
 
   def test_not_setting_cookie_with_secure
@@ -360,7 +381,7 @@ class CookiesTest < ActionController::TestCase
   def test_delete_unexisting_cookie
     request.cookies.clear
     get :delete_cookie
-    assert @response.cookies.empty?
+    assert_predicate @response.cookies, :empty?
   end
 
   def test_deleted_cookie_predicate
@@ -378,7 +399,7 @@ class CookiesTest < ActionController::TestCase
 
   def test_cookies_persist_throughout_request
     response = get :authenticate
-    assert response.headers["Set-Cookie"] =~ /user_name=david/
+    assert_match(/user_name=david/, response.headers["Set-Cookie"])
   end
 
   def test_set_permanent_cookie
@@ -651,6 +672,15 @@ class CookiesTest < ActionController::TestCase
     end
   end
 
+  def test_cookie_jar_mutated_by_request_persists_on_future_requests
+    get :authenticate
+    cookie_jar = @request.cookie_jar
+    cookie_jar.signed[:user_id] = 123
+    assert_equal ["user_name", "user_id"], @request.cookie_jar.instance_variable_get(:@cookies).keys
+    get :get_signed_cookie
+    assert_equal ["user_name", "user_id"], @request.cookie_jar.instance_variable_get(:@cookies).keys
+  end
+
   def test_raises_argument_error_if_missing_secret
     assert_raise(ArgumentError, nil.inspect) {
       @request.env["action_dispatch.key_generator"] = ActiveSupport::LegacyKeyGenerator.new(nil)
@@ -1072,11 +1102,11 @@ class CookiesTest < ActionController::TestCase
     assert_equal "david", cookies[:user_name]
 
     get :noop
-    assert_nil @response.headers["Set-Cookie"]
+    assert !@response.headers.include?("Set-Cookie")
     assert_equal "david", cookies[:user_name]
 
     get :noop
-    assert_nil @response.headers["Set-Cookie"]
+    assert !@response.headers.include?("Set-Cookie")
     assert_equal "david", cookies[:user_name]
   end
 
diff --git a/actionpack/test/dispatch/debug_exceptions_test.rb b/actionpack/test/dispatch/debug_exceptions_test.rb
index 1e5ed60b09..93258fbceb 100644
--- a/actionpack/test/dispatch/debug_exceptions_test.rb
+++ b/actionpack/test/dispatch/debug_exceptions_test.rb
@@ -71,14 +71,6 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
     end
   end
 
-  def setup
-    app = ActiveSupport::OrderedOptions.new
-    app.config = ActiveSupport::OrderedOptions.new
-    app.config.assets = ActiveSupport::OrderedOptions.new
-    app.config.assets.prefix = '/sprockets'
-    Rails.stubs(:application).returns(app)
-  end
-
   RoutesApp = Struct.new(:routes).new(SharedTestRoutes)
   ProductionApp  = ActionDispatch::DebugExceptions.new(Boomer.new(false), RoutesApp)
   DevelopmentApp = ActionDispatch::DebugExceptions.new(Boomer.new(true), RoutesApp)
@@ -86,21 +78,21 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   test 'skip diagnosis if not showing detailed exceptions' do
     @app = ProductionApp
     assert_raise RuntimeError do
-      get "/", {}, {'action_dispatch.show_exceptions' => true}
+      get "/", headers: { 'action_dispatch.show_exceptions' => true }
     end
   end
 
   test 'skip diagnosis if not showing exceptions' do
     @app = DevelopmentApp
     assert_raise RuntimeError do
-      get "/", {}, {'action_dispatch.show_exceptions' => false}
+      get "/", headers: { 'action_dispatch.show_exceptions' => false }
     end
   end
 
   test 'raise an exception on cascade pass' do
     @app = ProductionApp
     assert_raise ActionController::RoutingError do
-      get "/pass", {}, {'action_dispatch.show_exceptions' => true}
+      get "/pass", headers: { 'action_dispatch.show_exceptions' => true }
     end
   end
 
@@ -108,14 +100,14 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
     boomer = Boomer.new(false)
     @app = ActionDispatch::DebugExceptions.new(boomer)
     assert_raise ActionController::RoutingError do
-      get "/pass", {}, {'action_dispatch.show_exceptions' => true}
+      get "/pass", headers: { 'action_dispatch.show_exceptions' => true }
     end
     assert boomer.closed, "Expected to close the response body"
   end
 
   test 'displays routes in a table when a RoutingError occurs' do
     @app = DevelopmentApp
-    get "/pass", {}, {'action_dispatch.show_exceptions' => true}
+    get "/pass", headers: { 'action_dispatch.show_exceptions' => true }
     routing_table = body[/route_table.*<.table>/m]
     assert_match '/:controller(/:action)(.:format)', routing_table
     assert_match ':controller#:action', routing_table
@@ -125,7 +117,7 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   test 'displays request and response info when a RoutingError occurs' do
     @app = DevelopmentApp
 
-    get "/pass", {}, {'action_dispatch.show_exceptions' => true}
+    get "/pass", headers: { 'action_dispatch.show_exceptions' => true }
 
     assert_select 'h2', /Request/
     assert_select 'h2', /Response/
@@ -134,27 +126,27 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   test "rescue with diagnostics message" do
     @app = DevelopmentApp
 
-    get "/", {}, {'action_dispatch.show_exceptions' => true}
+    get "/", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 500
     assert_match(/puke/, body)
 
-    get "/not_found", {}, {'action_dispatch.show_exceptions' => true}
+    get "/not_found", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 404
     assert_match(/#{AbstractController::ActionNotFound.name}/, body)
 
-    get "/method_not_allowed", {}, {'action_dispatch.show_exceptions' => true}
+    get "/method_not_allowed", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 405
     assert_match(/ActionController::MethodNotAllowed/, body)
 
-    get "/unknown_http_method", {}, {'action_dispatch.show_exceptions' => true}
+    get "/unknown_http_method", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 405
     assert_match(/ActionController::UnknownHttpMethod/, body)
 
-    get "/bad_request", {}, {'action_dispatch.show_exceptions' => true}
+    get "/bad_request", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 400
     assert_match(/ActionController::BadRequest/, body)
 
-    get "/parameter_missing", {}, {'action_dispatch.show_exceptions' => true}
+    get "/parameter_missing", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 400
     assert_match(/ActionController::ParameterMissing/, body)
   end
@@ -163,38 +155,38 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
     @app = DevelopmentApp
     xhr_request_env = {'action_dispatch.show_exceptions' => true, 'HTTP_X_REQUESTED_WITH' => 'XMLHttpRequest'}
 
-    get "/", {}, xhr_request_env
+    get "/", headers: xhr_request_env
     assert_response 500
     assert_no_match(/<header>/, body)
     assert_no_match(/<body>/, body)
     assert_equal "text/plain", response.content_type
     assert_match(/RuntimeError\npuke/, body)
 
-    get "/not_found", {}, xhr_request_env
+    get "/not_found", headers: xhr_request_env
     assert_response 404
     assert_no_match(/<body>/, body)
     assert_equal "text/plain", response.content_type
     assert_match(/#{AbstractController::ActionNotFound.name}/, body)
 
-    get "/method_not_allowed", {}, xhr_request_env
+    get "/method_not_allowed", headers: xhr_request_env
     assert_response 405
     assert_no_match(/<body>/, body)
     assert_equal "text/plain", response.content_type
     assert_match(/ActionController::MethodNotAllowed/, body)
 
-    get "/unknown_http_method", {}, xhr_request_env
+    get "/unknown_http_method", headers: xhr_request_env
     assert_response 405
     assert_no_match(/<body>/, body)
     assert_equal "text/plain", response.content_type
     assert_match(/ActionController::UnknownHttpMethod/, body)
 
-    get "/bad_request", {}, xhr_request_env
+    get "/bad_request", headers: xhr_request_env
     assert_response 400
     assert_no_match(/<body>/, body)
     assert_equal "text/plain", response.content_type
     assert_match(/ActionController::BadRequest/, body)
 
-    get "/parameter_missing", {}, xhr_request_env
+    get "/parameter_missing", headers: xhr_request_env
     assert_response 400
     assert_no_match(/<body>/, body)
     assert_equal "text/plain", response.content_type
@@ -204,8 +196,8 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   test "does not show filtered parameters" do
     @app = DevelopmentApp
 
-    get "/", {"foo"=>"bar"}, {'action_dispatch.show_exceptions' => true,
-      'action_dispatch.parameter_filter' => [:foo]}
+    get "/", params: { "foo"=>"bar" }, headers: { 'action_dispatch.show_exceptions' => true,
+      'action_dispatch.parameter_filter' => [:foo] }
     assert_response 500
     assert_match("&quot;foo&quot;=&gt;&quot;[FILTERED]&quot;", body)
   end
@@ -213,7 +205,7 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   test "show registered original exception for wrapped exceptions" do
     @app = DevelopmentApp
 
-    get "/not_found_original_exception", {}, {'action_dispatch.show_exceptions' => true}
+    get "/not_found_original_exception", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 404
     assert_match(/AbstractController::ActionNotFound/, body)
   end
@@ -221,7 +213,7 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   test "named urls missing keys raise 500 level error" do
     @app = DevelopmentApp
 
-    get "/missing_keys", {}, {'action_dispatch.show_exceptions' => true}
+    get "/missing_keys", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 500
 
     assert_match(/ActionController::UrlGenerationError/, body)
@@ -229,7 +221,7 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
 
   test "show the controller name in the diagnostics template when controller name is present" do
     @app = DevelopmentApp
-    get("/runtime_error", {}, {
+    get("/runtime_error", headers: {
       'action_dispatch.show_exceptions' => true,
       'action_dispatch.request.parameters' => {
         'action' => 'show',
@@ -252,7 +244,7 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
       }
     }
 
-    get("/runtime_error", {}, {
+    get("/runtime_error", headers: {
       'action_dispatch.show_exceptions' => true,
       'action_dispatch.request.parameters' => {
         'action' => 'show',
@@ -267,22 +259,25 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   test "sets the HTTP charset parameter" do
     @app = DevelopmentApp
 
-    get "/", {}, {'action_dispatch.show_exceptions' => true}
+    get "/", headers: { 'action_dispatch.show_exceptions' => true }
     assert_equal "text/html; charset=utf-8", response.headers["Content-Type"]
   end
 
   test 'uses logger from env' do
     @app = DevelopmentApp
     output = StringIO.new
-    get "/", {}, {'action_dispatch.show_exceptions' => true, 'action_dispatch.logger' => Logger.new(output)}
+    get "/", headers: { 'action_dispatch.show_exceptions' => true, 'action_dispatch.logger' => Logger.new(output) }
     assert_match(/puke/, output.rewind && output.read)
   end
 
   test 'uses backtrace cleaner from env' do
     @app = DevelopmentApp
-    cleaner = stub(:clean => ['passed backtrace cleaner'])
-    get "/", {}, {'action_dispatch.show_exceptions' => true, 'action_dispatch.backtrace_cleaner' => cleaner}
-    assert_match(/passed backtrace cleaner/, body)
+    backtrace_cleaner = ActiveSupport::BacktraceCleaner.new
+
+    backtrace_cleaner.stub :clean, ['passed backtrace cleaner'] do
+      get "/", headers: { 'action_dispatch.show_exceptions' => true, 'action_dispatch.backtrace_cleaner' => backtrace_cleaner }
+      assert_match(/passed backtrace cleaner/, body)
+    end
   end
 
   test 'logs exception backtrace when all lines silenced' do
@@ -294,25 +289,25 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
            'action_dispatch.logger' => Logger.new(output),
            'action_dispatch.backtrace_cleaner' => backtrace_cleaner}
 
-    get "/", {}, env
+    get "/", headers: env
     assert_operator((output.rewind && output.read).lines.count, :>, 10)
   end
 
   test 'display backtrace when error type is SyntaxError' do
     @app = DevelopmentApp
 
-    get '/original_syntax_error', {}, {'action_dispatch.backtrace_cleaner' => ActiveSupport::BacktraceCleaner.new}
+    get '/original_syntax_error', headers: { 'action_dispatch.backtrace_cleaner' => ActiveSupport::BacktraceCleaner.new }
 
     assert_response 500
     assert_select '#Application-Trace' do
-      assert_select 'pre code', /\(eval\):1: syntax error, unexpected/
+      assert_select 'pre code', /syntax error, unexpected/
     end
   end
 
   test 'display backtrace on template missing errors' do
     @app = DevelopmentApp
 
-    get "/missing_template", nil, {}
+    get "/missing_template"
 
     assert_select "header h1", /Template is missing/
 
@@ -328,46 +323,47 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   test 'display backtrace when error type is SyntaxError wrapped by ActionView::Template::Error' do
     @app = DevelopmentApp
 
-    get '/syntax_error_into_view', {}, {'action_dispatch.backtrace_cleaner' => ActiveSupport::BacktraceCleaner.new}
+    get '/syntax_error_into_view', headers: { 'action_dispatch.backtrace_cleaner' => ActiveSupport::BacktraceCleaner.new }
 
     assert_response 500
     assert_select '#Application-Trace' do
-      assert_select 'pre code', /\(eval\):1: syntax error, unexpected/
+      assert_select 'pre code', /syntax error, unexpected/
     end
   end
 
   test 'debug exceptions app shows user code that caused the error in source view' do
     @app = DevelopmentApp
-    Rails.stubs(:root).returns(Pathname.new('.'))
-    cleaner = ActiveSupport::BacktraceCleaner.new.tap do |bc|
-      bc.add_silencer { |line| line =~ /method_that_raises/ }
-      bc.add_silencer { |line| line !~ %r{test/dispatch/debug_exceptions_test.rb} }
-    end
+    Rails.stub :root, Pathname.new('.') do
+      cleaner = ActiveSupport::BacktraceCleaner.new.tap do |bc|
+        bc.add_silencer { |line| line =~ /method_that_raises/ }
+        bc.add_silencer { |line| line !~ %r{test/dispatch/debug_exceptions_test.rb} }
+      end
 
-    get '/framework_raises', {}, {'action_dispatch.backtrace_cleaner' => cleaner}
+      get '/framework_raises', headers: { 'action_dispatch.backtrace_cleaner' => cleaner }
 
-    # Assert correct error
-    assert_response 500
-    assert_select 'h2', /error in framework/
+      # Assert correct error
+      assert_response 500
+      assert_select 'h2', /error in framework/
 
-    # assert source view line is the call to method_that_raises
-    assert_select 'div.source:not(.hidden)' do
-      assert_select 'pre .line.active', /method_that_raises/
-    end
+      # assert source view line is the call to method_that_raises
+      assert_select 'div.source:not(.hidden)' do
+        assert_select 'pre .line.active', /method_that_raises/
+      end
 
-    # assert first source view (hidden) that throws the error
-    assert_select 'div.source:first' do
-      assert_select 'pre .line.active', /raise StandardError\.new/
-    end
+      # assert first source view (hidden) that throws the error
+      assert_select 'div.source:first' do
+        assert_select 'pre .line.active', /raise StandardError\.new/
+      end
 
-    # assert application trace refers to line that calls method_that_raises is first
-    assert_select '#Application-Trace' do
-      assert_select 'pre code a:first', %r{test/dispatch/debug_exceptions_test\.rb:\d+:in `call}
-    end
+      # assert application trace refers to line that calls method_that_raises is first
+      assert_select '#Application-Trace' do
+        assert_select 'pre code a:first', %r{test/dispatch/debug_exceptions_test\.rb:\d+:in `call}
+      end
 
-    # assert framework trace that that threw the error is first
-    assert_select '#Framework-Trace' do
-      assert_select 'pre code a:first', /method_that_raises/
+      # assert framework trace that that threw the error is first
+      assert_select '#Framework-Trace' do
+        assert_select 'pre code a:first', /method_that_raises/
+      end
     end
   end
 end
diff --git a/actionpack/test/dispatch/exception_wrapper_test.rb b/actionpack/test/dispatch/exception_wrapper_test.rb
index d7408164ba..dfbb91c0ca 100644
--- a/actionpack/test/dispatch/exception_wrapper_test.rb
+++ b/actionpack/test/dispatch/exception_wrapper_test.rb
@@ -17,34 +17,49 @@ module ActionDispatch
     end
 
     setup do
-      Rails.stubs(:root).returns(Pathname.new('.'))
-
-      cleaner = ActiveSupport::BacktraceCleaner.new
-      cleaner.add_silencer { |line| line !~ /^lib/ }
-
-      @environment = { 'action_dispatch.backtrace_cleaner' => cleaner }
+      @cleaner = ActiveSupport::BacktraceCleaner.new
+      @cleaner.add_silencer { |line| line !~ /^lib/ }
     end
 
     test '#source_extracts fetches source fragments for every backtrace entry' do
       exception = TestError.new("lib/file.rb:42:in `index'")
-      wrapper = ExceptionWrapper.new({}, exception)
+      wrapper = ExceptionWrapper.new(nil, exception)
+
+      assert_called_with(wrapper, :source_fragment, ['lib/file.rb', 42], returns: 'foo') do
+        assert_equal [ code: 'foo', line_number: 42 ], wrapper.source_extracts
+      end
+    end
+
+    test '#source_extracts works with Windows paths' do
+      exc = TestError.new("c:/path/to/rails/app/controller.rb:27:in 'index':")
 
-      wrapper.expects(:source_fragment).with('lib/file.rb', 42).returns('foo')
+      wrapper = ExceptionWrapper.new(nil, exc)
 
-      assert_equal [ code: 'foo', line_number: 42 ], wrapper.source_extracts
+      assert_called_with(wrapper, :source_fragment, ['c:/path/to/rails/app/controller.rb', 27], returns: 'nothing') do
+        assert_equal [ code: 'nothing', line_number: 27 ], wrapper.source_extracts
+      end
     end
 
+    test '#source_extracts works with non standard backtrace' do
+      exc = TestError.new('invalid')
+
+      wrapper = ExceptionWrapper.new(nil, exc)
+
+      assert_called_with(wrapper, :source_fragment, ['invalid', 0], returns: 'nothing') do
+        assert_equal [ code: 'nothing', line_number: 0 ], wrapper.source_extracts
+      end
+    end
 
     test '#application_trace returns traces only from the application' do
       exception = TestError.new(caller.prepend("lib/file.rb:42:in `index'"))
-      wrapper = ExceptionWrapper.new(@environment, exception)
+      wrapper = ExceptionWrapper.new(@cleaner, exception)
 
       assert_equal [ "lib/file.rb:42:in `index'" ], wrapper.application_trace
     end
 
     test '#application_trace cannot be nil' do
-      nil_backtrace_wrapper = ExceptionWrapper.new(@environment, BadlyDefinedError.new)
-      nil_cleaner_wrapper = ExceptionWrapper.new({}, BadlyDefinedError.new)
+      nil_backtrace_wrapper = ExceptionWrapper.new(@cleaner, BadlyDefinedError.new)
+      nil_cleaner_wrapper = ExceptionWrapper.new(nil, BadlyDefinedError.new)
 
       assert_equal [], nil_backtrace_wrapper.application_trace
       assert_equal [], nil_cleaner_wrapper.application_trace
@@ -52,14 +67,14 @@ module ActionDispatch
 
     test '#framework_trace returns traces outside the application' do
       exception = TestError.new(caller.prepend("lib/file.rb:42:in `index'"))
-      wrapper = ExceptionWrapper.new(@environment, exception)
+      wrapper = ExceptionWrapper.new(@cleaner, exception)
 
       assert_equal caller, wrapper.framework_trace
     end
 
     test '#framework_trace cannot be nil' do
-      nil_backtrace_wrapper = ExceptionWrapper.new(@environment, BadlyDefinedError.new)
-      nil_cleaner_wrapper = ExceptionWrapper.new({}, BadlyDefinedError.new)
+      nil_backtrace_wrapper = ExceptionWrapper.new(@cleaner, BadlyDefinedError.new)
+      nil_cleaner_wrapper = ExceptionWrapper.new(nil, BadlyDefinedError.new)
 
       assert_equal [], nil_backtrace_wrapper.framework_trace
       assert_equal [], nil_cleaner_wrapper.framework_trace
@@ -67,14 +82,14 @@ module ActionDispatch
 
     test '#full_trace returns application and framework traces' do
       exception = TestError.new(caller.prepend("lib/file.rb:42:in `index'"))
-      wrapper = ExceptionWrapper.new(@environment, exception)
+      wrapper = ExceptionWrapper.new(@cleaner, exception)
 
       assert_equal exception.backtrace, wrapper.full_trace
     end
 
     test '#full_trace cannot be nil' do
-      nil_backtrace_wrapper = ExceptionWrapper.new(@environment, BadlyDefinedError.new)
-      nil_cleaner_wrapper = ExceptionWrapper.new({}, BadlyDefinedError.new)
+      nil_backtrace_wrapper = ExceptionWrapper.new(@cleaner, BadlyDefinedError.new)
+      nil_cleaner_wrapper = ExceptionWrapper.new(nil, BadlyDefinedError.new)
 
       assert_equal [], nil_backtrace_wrapper.full_trace
       assert_equal [], nil_cleaner_wrapper.full_trace
@@ -82,7 +97,7 @@ module ActionDispatch
 
     test '#traces returns every trace by category enumerated with an index' do
       exception = TestError.new("lib/file.rb:42:in `index'", "/gems/rack.rb:43:in `index'")
-      wrapper = ExceptionWrapper.new(@environment, exception)
+      wrapper = ExceptionWrapper.new(@cleaner, exception)
 
       assert_equal({
         'Application Trace' => [ id: 0, trace: "lib/file.rb:42:in `index'" ],
diff --git a/actionpack/test/dispatch/header_test.rb b/actionpack/test/dispatch/header_test.rb
index e2b38c23bc..7f1ef121b7 100644
--- a/actionpack/test/dispatch/header_test.rb
+++ b/actionpack/test/dispatch/header_test.rb
@@ -1,15 +1,19 @@
 require "abstract_unit"
 
 class HeaderTest < ActiveSupport::TestCase
+  def make_headers(hash)
+    ActionDispatch::Http::Headers.new ActionDispatch::Request.new hash
+  end
+
   setup do
-    @headers = ActionDispatch::Http::Headers.new(
+    @headers = make_headers(
       "CONTENT_TYPE" => "text/plain",
       "HTTP_REFERER" => "/some/page"
     )
   end
 
   test "#new does not normalize the data" do
-    headers = ActionDispatch::Http::Headers.new(
+    headers = make_headers(
       "Content-Type" => "application/json",
       "HTTP_REFERER" => "/some/page",
       "Host" => "http://test.com")
@@ -38,6 +42,24 @@ class HeaderTest < ActiveSupport::TestCase
     assert_equal "127.0.0.1", @headers["HTTP_HOST"]
   end
 
+  test "add to multivalued headers" do
+    # Sets header when not present
+    @headers.add 'Foo', '1'
+    assert_equal '1', @headers['Foo']
+
+    # Ignores nil values
+    @headers.add 'Foo', nil
+    assert_equal '1', @headers['Foo']
+
+    # Converts value to string
+    @headers.add 'Foo', 1
+    assert_equal '1,1', @headers['Foo']
+
+    # Case-insensitive
+    @headers.add 'fOo', 2
+    assert_equal '1,1,2', @headers['foO']
+  end
+
   test "headers can contain numbers" do
     @headers["Content-MD5"] = "Q2hlY2sgSW50ZWdyaXR5IQ=="
 
@@ -108,7 +130,7 @@ class HeaderTest < ActiveSupport::TestCase
   end
 
   test "env variables with . are not modified" do
-    headers = ActionDispatch::Http::Headers.new
+    headers = make_headers({})
     headers.merge! "rack.input" => "",
      "rack.request.cookie_hash" => "",
      "action_dispatch.logger" => ""
@@ -119,7 +141,7 @@ class HeaderTest < ActiveSupport::TestCase
   end
 
   test "symbols are treated as strings" do
-    headers = ActionDispatch::Http::Headers.new
+    headers = make_headers({})
     headers.merge!(:SERVER_NAME => "example.com",
                    "HTTP_REFERER" => "/",
                    :Host => "test.com")
@@ -130,7 +152,7 @@ class HeaderTest < ActiveSupport::TestCase
 
   test "headers directly modifies the passed environment" do
     env = {"HTTP_REFERER" => "/"}
-    headers = ActionDispatch::Http::Headers.new(env)
+    headers = make_headers(env)
     headers['Referer'] = "http://example.com/"
     headers.merge! "CONTENT_TYPE" => "text/plain"
     assert_equal({"HTTP_REFERER"=>"http://example.com/",
diff --git a/actionpack/test/dispatch/live_response_test.rb b/actionpack/test/dispatch/live_response_test.rb
index 512f3a8a7a..55becc1c91 100644
--- a/actionpack/test/dispatch/live_response_test.rb
+++ b/actionpack/test/dispatch/live_response_test.rb
@@ -1,5 +1,5 @@
 require 'abstract_unit'
-require 'active_support/concurrency/latch'
+require 'concurrent/atomics'
 
 module ActionController
   module Live
@@ -27,18 +27,18 @@ module ActionController
       end
 
       def test_parallel
-        latch = ActiveSupport::Concurrency::Latch.new
+        latch = Concurrent::CountDownLatch.new
 
         t = Thread.new {
           @response.stream.write 'foo'
-          latch.await
+          latch.wait
           @response.stream.close
         }
 
         @response.await_commit
         @response.each do |part|
           assert_equal 'foo', part
-          latch.release
+          latch.count_down
         end
         assert t.join
       end
@@ -62,15 +62,15 @@ module ActionController
 
       def test_headers_cannot_be_written_after_webserver_reads
         @response.stream.write 'omg'
-        latch = ActiveSupport::Concurrency::Latch.new
+        latch = Concurrent::CountDownLatch.new
 
         t = Thread.new {
-          @response.stream.each do |chunk|
-            latch.release
+          @response.stream.each do
+            latch.count_down
           end
         }
 
-        latch.await
+        latch.wait
         assert @response.headers.frozen?
         e = assert_raises(ActionDispatch::IllegalStateError) do
           @response.headers['Content-Length'] = "zomg"
@@ -83,6 +83,8 @@ module ActionController
 
       def test_headers_cannot_be_written_after_close
         @response.stream.close
+        # we can add data until it's actually written, which happens on `each`
+        @response.each { |x| }
 
         e = assert_raises(ActionDispatch::IllegalStateError) do
           @response.headers['Content-Length'] = "zomg"
diff --git a/actionpack/test/dispatch/mapper_test.rb b/actionpack/test/dispatch/mapper_test.rb
index 889f9a4736..e783df855e 100644
--- a/actionpack/test/dispatch/mapper_test.rb
+++ b/actionpack/test/dispatch/mapper_test.rb
@@ -4,13 +4,6 @@ module ActionDispatch
   module Routing
     class MapperTest < ActiveSupport::TestCase
       class FakeSet < ActionDispatch::Routing::RouteSet
-        attr_reader :routes
-        alias :set :routes
-
-        def initialize
-          @routes = []
-        end
-
         def resources_path_names
           {}
         end
@@ -19,16 +12,24 @@ module ActionDispatch
           ActionDispatch::Request
         end
 
-        def add_route(*args)
-          routes << args
+        def dispatcher_class
+          RouteSet::Dispatcher
+        end
+
+        def defaults
+          routes.map(&:defaults)
         end
 
         def conditions
-          routes.map { |x| x[1] }
+          routes.map(&:constraints)
         end
 
         def requirements
-          routes.map { |x| x[2] }
+          routes.map(&:path).map(&:requirements)
+        end
+
+        def asts
+          routes.map(&:path).map(&:spec)
         end
       end
 
@@ -36,18 +37,76 @@ module ActionDispatch
         Mapper.new FakeSet.new
       end
 
+      def test_scope_raises_on_anchor
+        fakeset = FakeSet.new
+        mapper = Mapper.new fakeset
+        assert_raises(ArgumentError) do
+          mapper.scope(anchor: false) do
+          end
+        end
+      end
+
+      def test_blows_up_without_via
+        fakeset = FakeSet.new
+        mapper = Mapper.new fakeset
+        assert_raises(ArgumentError) do
+          mapper.match '/', :to => 'posts#index', :as => :main
+        end
+      end
+
+      def test_unscoped_formatted
+        fakeset = FakeSet.new
+        mapper = Mapper.new fakeset
+        mapper.get '/foo', :to => 'posts#index', :as => :main, :format => true
+        assert_equal({:controller=>"posts", :action=>"index"},
+                     fakeset.defaults.first)
+        assert_equal "/foo.:format", fakeset.asts.first.to_s
+      end
+
+      def test_scoped_formatted
+        fakeset = FakeSet.new
+        mapper = Mapper.new fakeset
+        mapper.scope(format: true) do
+          mapper.get '/foo', :to => 'posts#index', :as => :main
+        end
+        assert_equal({:controller=>"posts", :action=>"index"},
+                     fakeset.defaults.first)
+        assert_equal "/foo.:format", fakeset.asts.first.to_s
+      end
+
+      def test_random_keys
+        fakeset = FakeSet.new
+        mapper = Mapper.new fakeset
+        mapper.scope(omg: :awesome) do
+          mapper.get '/', :to => 'posts#index', :as => :main
+        end
+        assert_equal({:omg=>:awesome, :controller=>"posts", :action=>"index"},
+                     fakeset.defaults.first)
+        assert_equal("GET", fakeset.routes.first.verb)
+      end
+
       def test_mapping_requirements
-        options = { :controller => 'foo', :action => 'bar', :via => :get }
-        m = Mapper::Mapping.build({}, FakeSet.new, '/store/:name(*rest)', nil, options)
-        _, _, requirements, _ = m.to_route
-        assert_equal(/.+?/, requirements[:rest])
+        options = { }
+        scope = Mapper::Scope.new({})
+        ast = Journey::Parser.parse '/store/:name(*rest)'
+        m = Mapper::Mapping.build(scope, FakeSet.new, ast, 'foo', 'bar', nil, [:get], nil, {}, true, options)
+        assert_equal(/.+?/, m.requirements[:rest])
+      end
+
+      def test_via_scope
+        fakeset = FakeSet.new
+        mapper = Mapper.new fakeset
+        mapper.scope(via: :put) do
+          mapper.match '/', :to => 'posts#index', :as => :main
+        end
+        assert_equal("PUT", fakeset.routes.first.verb)
       end
 
       def test_map_slash
         fakeset = FakeSet.new
         mapper = Mapper.new fakeset
         mapper.get '/', :to => 'posts#index', :as => :main
-        assert_equal '/', fakeset.conditions.first[:path_info]
+        assert_equal '/', fakeset.asts.first.to_s
       end
 
       def test_map_more_slashes
@@ -56,14 +115,14 @@ module ActionDispatch
 
         # FIXME: is this a desired behavior?
         mapper.get '/one/two/', :to => 'posts#index', :as => :main
-        assert_equal '/one/two(.:format)', fakeset.conditions.first[:path_info]
+        assert_equal '/one/two(.:format)', fakeset.asts.first.to_s
       end
 
       def test_map_wildcard
         fakeset = FakeSet.new
         mapper = Mapper.new fakeset
         mapper.get '/*path', :to => 'pages#show'
-        assert_equal '/*path(.:format)', fakeset.conditions.first[:path_info]
+        assert_equal '/*path(.:format)', fakeset.asts.first.to_s
         assert_equal(/.+?/, fakeset.requirements.first[:path])
       end
 
@@ -71,7 +130,7 @@ module ActionDispatch
         fakeset = FakeSet.new
         mapper = Mapper.new fakeset
         mapper.get '/*path/foo/:bar', :to => 'pages#show'
-        assert_equal '/*path/foo/:bar(.:format)', fakeset.conditions.first[:path_info]
+        assert_equal '/*path/foo/:bar(.:format)', fakeset.asts.first.to_s
         assert_equal(/.+?/, fakeset.requirements.first[:path])
       end
 
@@ -79,7 +138,7 @@ module ActionDispatch
         fakeset = FakeSet.new
         mapper = Mapper.new fakeset
         mapper.get '/*foo/*bar', :to => 'pages#show'
-        assert_equal '/*foo/*bar(.:format)', fakeset.conditions.first[:path_info]
+        assert_equal '/*foo/*bar(.:format)', fakeset.asts.first.to_s
         assert_equal(/.+?/, fakeset.requirements.first[:foo])
         assert_equal(/.+?/, fakeset.requirements.first[:bar])
       end
@@ -88,7 +147,7 @@ module ActionDispatch
         fakeset = FakeSet.new
         mapper = Mapper.new fakeset
         mapper.get '/*path', :to => 'pages#show', :format => false
-        assert_equal '/*path', fakeset.conditions.first[:path_info]
+        assert_equal '/*path', fakeset.asts.first.to_s
         assert_nil fakeset.requirements.first[:path]
       end
 
@@ -96,7 +155,7 @@ module ActionDispatch
         fakeset = FakeSet.new
         mapper = Mapper.new fakeset
         mapper.get '/*path', :to => 'pages#show', :format => true
-        assert_equal '/*path.:format', fakeset.conditions.first[:path_info]
+        assert_equal '/*path.:format', fakeset.asts.first.to_s
       end
 
       def test_raising_helpful_error_on_invalid_arguments
diff --git a/actionpack/test/dispatch/middleware_stack/middleware_test.rb b/actionpack/test/dispatch/middleware_stack/middleware_test.rb
deleted file mode 100644
index 9607f026db..0000000000
--- a/actionpack/test/dispatch/middleware_stack/middleware_test.rb
+++ /dev/null
@@ -1,77 +0,0 @@
-require 'abstract_unit'
-require 'action_dispatch/middleware/stack'
-
-module ActionDispatch
-  class MiddlewareStack
-    class MiddlewareTest < ActiveSupport::TestCase
-      class Omg; end
-
-      {
-        'concrete'  => Omg,
-        'anonymous' => Class.new
-      }.each do |name, klass|
-
-        define_method("test_#{name}_klass") do
-          mw = Middleware.new klass
-          assert_equal klass, mw.klass
-        end
-
-        define_method("test_#{name}_==") do
-          mw1 = Middleware.new klass
-          mw2 = Middleware.new klass
-          assert_equal mw1, mw2
-        end
-
-      end
-
-      def test_string_class
-        mw = Middleware.new Omg.name
-        assert_equal Omg, mw.klass
-      end
-
-      def test_double_equal_works_with_classes
-        k = Class.new
-        mw = Middleware.new k
-        assert_operator mw, :==, k
-
-        result = mw != Class.new
-        assert result, 'middleware should not equal other anon class'
-      end
-
-      def test_double_equal_works_with_strings
-        mw = Middleware.new Omg
-        assert_operator mw, :==, Omg.name
-      end
-
-      def test_double_equal_normalizes_strings
-        mw = Middleware.new Omg
-        assert_operator mw, :==, "::#{Omg.name}"
-      end
-
-      def test_middleware_loads_classnames_from_cache
-        mw = Class.new(Middleware) {
-          attr_accessor :classcache
-        }.new(Omg.name)
-
-        fake_cache    = { mw.name => Omg }
-        mw.classcache = fake_cache
-
-        assert_equal Omg, mw.klass
-
-        fake_cache[mw.name] = Middleware
-        assert_equal Middleware, mw.klass
-      end
-
-      def test_middleware_always_returns_class
-        mw = Class.new(Middleware) {
-          attr_accessor :classcache
-        }.new(Omg)
-
-        fake_cache    = { mw.name => Middleware }
-        mw.classcache = fake_cache
-
-        assert_equal Omg, mw.klass
-      end
-    end
-  end
-end
diff --git a/actionpack/test/dispatch/middleware_stack_test.rb b/actionpack/test/dispatch/middleware_stack_test.rb
index 948a690979..33aa616474 100644
--- a/actionpack/test/dispatch/middleware_stack_test.rb
+++ b/actionpack/test/dispatch/middleware_stack_test.rb
@@ -4,6 +4,7 @@ class MiddlewareStackTest < ActiveSupport::TestCase
   class FooMiddleware; end
   class BarMiddleware; end
   class BazMiddleware; end
+  class HiyaMiddleware; end
   class BlockMiddleware
     attr_reader :block
     def initialize(&block)
@@ -17,6 +18,20 @@ class MiddlewareStackTest < ActiveSupport::TestCase
     @stack.use BarMiddleware
   end
 
+  def test_delete_with_string_is_deprecated
+    assert_deprecated do
+      assert_difference "@stack.size", -1 do
+        @stack.delete FooMiddleware.name
+      end
+    end
+  end
+
+  def test_delete_works
+    assert_difference "@stack.size", -1 do
+      @stack.delete FooMiddleware
+    end
+  end
+
   test "use should push middleware as class onto the stack" do
     assert_difference "@stack.size" do
       @stack.use BazMiddleware
@@ -25,17 +40,21 @@ class MiddlewareStackTest < ActiveSupport::TestCase
   end
 
   test "use should push middleware as a string onto the stack" do
-    assert_difference "@stack.size" do
-      @stack.use "MiddlewareStackTest::BazMiddleware"
+    assert_deprecated do
+      assert_difference "@stack.size" do
+        @stack.use "MiddlewareStackTest::BazMiddleware"
+      end
+      assert_equal BazMiddleware, @stack.last.klass
     end
-    assert_equal BazMiddleware, @stack.last.klass
   end
 
   test "use should push middleware as a symbol onto the stack" do
-    assert_difference "@stack.size" do
-      @stack.use :"MiddlewareStackTest::BazMiddleware"
+    assert_deprecated do
+      assert_difference "@stack.size" do
+        @stack.use :"MiddlewareStackTest::BazMiddleware"
+      end
+      assert_equal BazMiddleware, @stack.last.klass
     end
-    assert_equal BazMiddleware, @stack.last.klass
   end
 
   test "use should push middleware class with arguments onto the stack" do
@@ -88,30 +107,28 @@ class MiddlewareStackTest < ActiveSupport::TestCase
   end
 
   test "unshift adds a new middleware at the beginning of the stack" do
-    @stack.unshift :"MiddlewareStackTest::BazMiddleware"
-    assert_equal BazMiddleware, @stack.first.klass
+    assert_deprecated do
+      @stack.unshift :"MiddlewareStackTest::BazMiddleware"
+      assert_equal BazMiddleware, @stack.first.klass
+    end
   end
 
   test "raise an error on invalid index" do
     assert_raise RuntimeError do
-      @stack.insert("HiyaMiddleware", BazMiddleware)
+      @stack.insert(HiyaMiddleware, BazMiddleware)
     end
 
     assert_raise RuntimeError do
-      @stack.insert_after("HiyaMiddleware", BazMiddleware)
+      @stack.insert_after(HiyaMiddleware, BazMiddleware)
     end
   end
 
   test "lazy evaluates middleware class" do
-    assert_difference "@stack.size" do
-      @stack.use "MiddlewareStackTest::BazMiddleware"
+    assert_deprecated do
+      assert_difference "@stack.size" do
+        @stack.use "MiddlewareStackTest::BazMiddleware"
+      end
+      assert_equal BazMiddleware, @stack.last.klass
     end
-    assert_equal BazMiddleware, @stack.last.klass
-  end
-
-  test "lazy compares so unloaded constants are not loaded" do
-    @stack.use "UnknownMiddleware"
-    @stack.use :"MiddlewareStackTest::BazMiddleware"
-    assert @stack.include?("::MiddlewareStackTest::BazMiddleware")
   end
 end
diff --git a/actionpack/test/dispatch/mime_type_test.rb b/actionpack/test/dispatch/mime_type_test.rb
index 3017a9c2d6..149e37bf3d 100644
--- a/actionpack/test/dispatch/mime_type_test.rb
+++ b/actionpack/test/dispatch/mime_type_test.rb
@@ -1,7 +1,6 @@
 require 'abstract_unit'
 
 class MimeTypeTest < ActiveSupport::TestCase
-
   test "parse single" do
     Mime::LOOKUP.each_key do |mime_type|
       unless mime_type == 'image/*'
@@ -11,97 +10,95 @@ class MimeTypeTest < ActiveSupport::TestCase
   end
 
   test "unregister" do
+    assert_nil Mime[:mobile]
+
     begin
-      Mime::Type.register("text/x-mobile", :mobile)
-      assert defined?(Mime::MOBILE)
-      assert_equal Mime::MOBILE, Mime::LOOKUP['text/x-mobile']
-      assert_equal Mime::MOBILE, Mime::EXTENSION_LOOKUP['mobile']
+      mime = Mime::Type.register("text/x-mobile", :mobile)
+      assert_equal mime, Mime[:mobile]
+      assert_equal mime, Mime::Type.lookup('text/x-mobile')
+      assert_equal mime, Mime::Type.lookup_by_extension(:mobile)
 
       Mime::Type.unregister(:mobile)
-      assert !defined?(Mime::MOBILE), "Mime::MOBILE should not be defined"
-      assert !Mime::LOOKUP.has_key?('text/x-mobile'), "Mime::LOOKUP should not have key ['text/x-mobile]"
-      assert !Mime::EXTENSION_LOOKUP.has_key?('mobile'), "Mime::EXTENSION_LOOKUP should not have key ['mobile]"
+      assert_nil Mime[:mobile], "Mime[:mobile] should be nil after unregistering :mobile"
+      assert_nil Mime::Type.lookup_by_extension(:mobile), "Should be missing MIME extension lookup for :mobile"
     ensure
-      Mime.module_eval { remove_const :MOBILE if const_defined?(:MOBILE) }
-      Mime::LOOKUP.reject!{|key,_| key == 'text/x-mobile'}
+      Mime::Type.unregister :mobile
     end
   end
 
   test "parse text with trailing star at the beginning" do
     accept = "text/*, text/html, application/json, multipart/form-data"
-    expect = [Mime::HTML, Mime::TEXT, Mime::JS, Mime::CSS, Mime::ICS, Mime::CSV, Mime::VCF, Mime::XML, Mime::YAML, Mime::JSON, Mime::MULTIPART_FORM]
+    expect = [Mime[:html], Mime[:text], Mime[:js], Mime[:css], Mime[:ics], Mime[:csv], Mime[:vcf], Mime[:xml], Mime[:yaml], Mime[:json], Mime[:multipart_form]]
     parsed = Mime::Type.parse(accept)
     assert_equal expect, parsed
   end
 
   test "parse text with trailing star in the end" do
     accept = "text/html, application/json, multipart/form-data, text/*"
-    expect = [Mime::HTML, Mime::JSON, Mime::MULTIPART_FORM, Mime::TEXT, Mime::JS, Mime::CSS, Mime::ICS, Mime::CSV, Mime::VCF, Mime::XML, Mime::YAML]
+    expect = [Mime[:html], Mime[:json], Mime[:multipart_form], Mime[:text], Mime[:js], Mime[:css], Mime[:ics], Mime[:csv], Mime[:vcf], Mime[:xml], Mime[:yaml]]
     parsed = Mime::Type.parse(accept)
     assert_equal expect, parsed
   end
 
   test "parse text with trailing star" do
     accept = "text/*"
-    expect = [Mime::HTML, Mime::TEXT, Mime::JS, Mime::CSS, Mime::ICS, Mime::CSV, Mime::VCF, Mime::XML, Mime::YAML, Mime::JSON]
+    expect = [Mime[:html], Mime[:text], Mime[:js], Mime[:css], Mime[:ics], Mime[:csv], Mime[:vcf], Mime[:xml], Mime[:yaml], Mime[:json]]
     parsed = Mime::Type.parse(accept)
     assert_equal expect, parsed
   end
 
   test "parse application with trailing star" do
     accept = "application/*"
-    expect = [Mime::HTML, Mime::JS, Mime::XML, Mime::RSS, Mime::ATOM, Mime::YAML, Mime::URL_ENCODED_FORM, Mime::JSON, Mime::PDF, Mime::ZIP]
+    expect = [Mime[:html], Mime[:js], Mime[:xml], Mime[:rss], Mime[:atom], Mime[:yaml], Mime[:url_encoded_form], Mime[:json], Mime[:pdf], Mime[:zip]]
     parsed = Mime::Type.parse(accept)
     assert_equal expect, parsed
   end
 
   test "parse without q" do
     accept = "text/xml,application/xhtml+xml,text/yaml,application/xml,text/html,image/png,text/plain,application/pdf,*/*"
-    expect = [Mime::HTML, Mime::XML, Mime::YAML, Mime::PNG, Mime::TEXT, Mime::PDF, Mime::ALL]
-    assert_equal expect, Mime::Type.parse(accept)
+    expect = [Mime[:html], Mime[:xml], Mime[:yaml], Mime[:png], Mime[:text], Mime[:pdf], '*/*']
+    assert_equal expect.map(&:to_s), Mime::Type.parse(accept).map(&:to_s)
   end
 
   test "parse with q" do
     accept = "text/xml,application/xhtml+xml,text/yaml; q=0.3,application/xml,text/html; q=0.8,image/png,text/plain; q=0.5,application/pdf,*/*; q=0.2"
-    expect = [Mime::HTML, Mime::XML, Mime::PNG, Mime::PDF, Mime::TEXT, Mime::YAML, Mime::ALL]
-    assert_equal expect, Mime::Type.parse(accept)
+    expect = [Mime[:html], Mime[:xml], Mime[:png], Mime[:pdf], Mime[:text], Mime[:yaml], '*/*']
+    assert_equal expect.map(&:to_s), Mime::Type.parse(accept).map(&:to_s)
   end
 
   test "parse single media range with q" do
     accept = "text/html;q=0.9"
-    expect = [Mime::HTML]
+    expect = [Mime[:html]]
     assert_equal expect, Mime::Type.parse(accept)
   end
 
   test "parse arbitrary media type parameters" do
     accept = 'multipart/form-data; boundary="simple boundary"'
-    expect = [Mime::MULTIPART_FORM]
+    expect = [Mime[:multipart_form]]
     assert_equal expect, Mime::Type.parse(accept)
   end
 
   # Accept header send with user HTTP_USER_AGENT: Sunrise/0.42j (Windows XP)
   test "parse broken acceptlines" do
     accept = "text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/*,,*/*;q=0.5"
-    expect = [Mime::HTML, Mime::XML, "image/*", Mime::TEXT, Mime::ALL]
-    assert_equal expect, Mime::Type.parse(accept).collect(&:to_s)
+    expect = [Mime[:html], Mime[:xml], "image/*", Mime[:text], '*/*']
+    assert_equal expect.map(&:to_s), Mime::Type.parse(accept).map(&:to_s)
   end
 
   # Accept header send with user HTTP_USER_AGENT: Mozilla/4.0
   #  (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; InfoPath.1)
   test "parse other broken acceptlines" do
     accept = "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword,  , pronto/1.00.00, sslvpn/1.00.00.00, */*"
-    expect = ['image/gif', 'image/x-xbitmap', 'image/jpeg','image/pjpeg', 'application/x-shockwave-flash', 'application/vnd.ms-excel', 'application/vnd.ms-powerpoint', 'application/msword', 'pronto/1.00.00', 'sslvpn/1.00.00.00', Mime::ALL]
-    assert_equal expect, Mime::Type.parse(accept).collect(&:to_s)
+    expect = ['image/gif', 'image/x-xbitmap', 'image/jpeg','image/pjpeg', 'application/x-shockwave-flash', 'application/vnd.ms-excel', 'application/vnd.ms-powerpoint', 'application/msword', 'pronto/1.00.00', 'sslvpn/1.00.00.00', '*/*']
+    assert_equal expect.map(&:to_s), Mime::Type.parse(accept).map(&:to_s)
   end
 
   test "custom type" do
     begin
-      Mime::Type.register("image/foo", :foo)
-      assert_nothing_raised do
-        assert_equal Mime::FOO, Mime::SET.last
-      end
+      type = Mime::Type.register("image/foo", :foo)
+      assert_equal type, Mime[:foo]
     ensure
-      Mime::Type.unregister(:FOO)
+      Mime::Type.unregister(:foo)
     end
   end
 
@@ -109,10 +106,10 @@ class MimeTypeTest < ActiveSupport::TestCase
     begin
       Mime::Type.register "text/foobar", :foobar, ["text/foo", "text/bar"]
       %w[text/foobar text/foo text/bar].each do |type|
-        assert_equal Mime::FOOBAR, type
+        assert_equal Mime[:foobar], type
       end
     ensure
-      Mime::Type.unregister(:FOOBAR)
+      Mime::Type.unregister(:foobar)
     end
   end
 
@@ -123,10 +120,10 @@ class MimeTypeTest < ActiveSupport::TestCase
         registered_mimes << mime
       end
 
-      Mime::Type.register("text/foo", :foo)
-      assert_equal [Mime::FOO], registered_mimes
+      mime = Mime::Type.register("text/foo", :foo)
+      assert_equal [mime], registered_mimes
     ensure
-      Mime::Type.unregister(:FOO)
+      Mime::Type.unregister(:foo)
     end
   end
 
@@ -134,70 +131,67 @@ class MimeTypeTest < ActiveSupport::TestCase
     begin
       Mime::Type.register "text/foobar", :foobar, [], [:foo, "bar"]
       %w[foobar foo bar].each do |extension|
-        assert_equal Mime::FOOBAR, Mime::EXTENSION_LOOKUP[extension]
+        assert_equal Mime[:foobar], Mime::EXTENSION_LOOKUP[extension]
       end
     ensure
-      Mime::Type.unregister(:FOOBAR)
+      Mime::Type.unregister(:foobar)
     end
   end
 
   test "register alias" do
     begin
       Mime::Type.register_alias "application/xhtml+xml", :foobar
-      assert_equal Mime::HTML, Mime::EXTENSION_LOOKUP['foobar']
+      assert_equal Mime[:html], Mime::EXTENSION_LOOKUP['foobar']
     ensure
-      Mime::Type.unregister(:FOOBAR)
+      Mime::Type.unregister(:foobar)
     end
   end
 
   test "type should be equal to symbol" do
-    assert_equal Mime::HTML, 'application/xhtml+xml'
-    assert_equal Mime::HTML, :html
+    assert_equal Mime[:html], 'application/xhtml+xml'
+    assert_equal Mime[:html], :html
   end
 
   test "type convenience methods" do
-    # Don't test Mime::ALL, since it Mime::ALL#html? == true
-    types = Mime::SET.symbols.uniq - [:all, :iphone]
-
-    # Remove custom Mime::Type instances set in other tests, like Mime::GIF and Mime::IPHONE
-    types.delete_if { |type| !Mime.const_defined?(type.upcase) }
-
+    types = Mime::SET.symbols.uniq - [:iphone]
 
     types.each do |type|
-      mime = Mime.const_get(type.upcase)
+      mime = Mime[type]
       assert mime.respond_to?("#{type}?"), "#{mime.inspect} does not respond to #{type}?"
-      assert mime.send("#{type}?"), "#{mime.inspect} is not #{type}?"
+      assert_equal type, mime.symbol, "#{mime.inspect} is not #{type}?"
       invalid_types = types - [type]
-      invalid_types.delete(:html) if Mime::Type.html_types.include?(type)
-      invalid_types.each { |other_type| assert !mime.send("#{other_type}?"), "#{mime.inspect} is #{other_type}?" }
+      invalid_types.delete(:html)
+      invalid_types.each { |other_type|
+        assert_not_equal mime.symbol, other_type, "#{mime.inspect} is #{other_type}?"
+      }
     end
   end
 
-  test "mime all is html" do
-    assert Mime::ALL.all?,  "Mime::ALL is not all?"
-    assert Mime::ALL.html?, "Mime::ALL is not html?"
+  test "deprecated lookup" do
+    assert_deprecated do
+      Mime::HTML
+    end
   end
 
-  test "verifiable mime types" do
-    all_types = Mime::SET.symbols
-    all_types.uniq!
-    # Remove custom Mime::Type instances set in other tests, like Mime::GIF and Mime::IPHONE
-    all_types.delete_if { |type| !Mime.const_defined?(type.upcase) }
+  test "deprecated const_defined?" do
+    assert_deprecated do
+      Mime.const_defined? :HTML
+    end
   end
 
   test "references gives preference to symbols before strings" do
-    assert_equal :html, Mime::HTML.ref
+    assert_equal :html, Mime[:html].ref
     another = Mime::Type.lookup("foo/bar")
     assert_nil another.to_sym
     assert_equal "foo/bar", another.ref
   end
 
   test "regexp matcher" do
-    assert Mime::JS =~ "text/javascript"
-    assert Mime::JS =~ "application/javascript"
-    assert Mime::JS !~ "text/html"
-    assert !(Mime::JS !~ "text/javascript")
-    assert !(Mime::JS !~ "application/javascript")
-    assert Mime::HTML =~ 'application/xhtml+xml'
+    assert Mime[:js] =~ "text/javascript"
+    assert Mime[:js] =~ "application/javascript"
+    assert Mime[:js] !~ "text/html"
+    assert !(Mime[:js] !~ "text/javascript")
+    assert !(Mime[:js] !~ "application/javascript")
+    assert Mime[:html] =~ 'application/xhtml+xml'
   end
 end
diff --git a/actionpack/test/dispatch/mount_test.rb b/actionpack/test/dispatch/mount_test.rb
index d5a4d8ee11..d027f09762 100644
--- a/actionpack/test/dispatch/mount_test.rb
+++ b/actionpack/test/dispatch/mount_test.rb
@@ -49,7 +49,7 @@ class TestRoutingMount < ActionDispatch::IntegrationTest
   def test_app_name_is_properly_generated_when_engine_is_mounted_in_resources
     assert Router.mounted_helpers.method_defined?(:user_fake_mounted_at_resource),
           "A mounted helper should be defined with a parent's prefix"
-    assert Router.named_routes.routes[:user_fake_mounted_at_resource],
+    assert Router.named_routes.key?(:user_fake_mounted_at_resource),
           "A named route should be defined with a parent's prefix"
   end
 
@@ -64,7 +64,7 @@ class TestRoutingMount < ActionDispatch::IntegrationTest
   end
 
   def test_mounting_works_with_nested_script_name
-    get "/foo/sprockets/omg", {}, 'SCRIPT_NAME' => '/foo', 'PATH_INFO' => '/sprockets/omg'
+    get "/foo/sprockets/omg", headers: { 'SCRIPT_NAME' => '/foo', 'PATH_INFO' => '/sprockets/omg' }
     assert_equal "/foo/sprockets -- /omg", response.body
   end
 
diff --git a/actionpack/test/dispatch/prefix_generation_test.rb b/actionpack/test/dispatch/prefix_generation_test.rb
index f90d5499d7..d75e31db62 100644
--- a/actionpack/test/dispatch/prefix_generation_test.rb
+++ b/actionpack/test/dispatch/prefix_generation_test.rb
@@ -73,26 +73,26 @@ module TestGenerationPrefix
       include RailsApplication.routes.mounted_helpers
 
       def index
-        render :text => posts_path
+        render plain: posts_path
       end
 
       def show
-        render :text => post_path(:id => params[:id])
+        render plain: post_path(id: params[:id])
       end
 
       def url_to_application
         path = main_app.url_for(:controller => "outside_engine_generating",
                                 :action => "index",
                                 :only_path => true)
-        render :text => path
+        render plain: path
       end
 
       def polymorphic_path_for_engine
-        render :text => polymorphic_path(Post.new)
+        render plain: polymorphic_path(Post.new)
       end
 
       def conflicting
-        render :text => "engine"
+        render plain: "engine"
       end
     end
 
@@ -101,28 +101,28 @@ module TestGenerationPrefix
       include RailsApplication.routes.url_helpers
 
       def index
-        render :text => blog_engine.post_path(:id => 1)
+        render plain: blog_engine.post_path(id: 1)
       end
 
       def polymorphic_path_for_engine
-        render :text => blog_engine.polymorphic_path(Post.new)
+        render plain: blog_engine.polymorphic_path(Post.new)
       end
 
       def polymorphic_path_for_app
-        render :text => polymorphic_path(Post.new)
+        render plain: polymorphic_path(Post.new)
       end
 
       def polymorphic_with_url_for
-        render :text => blog_engine.url_for(Post.new)
+        render plain: blog_engine.url_for(Post.new)
       end
 
       def conflicting
-        render :text => "application"
+        render plain: "application"
       end
 
       def ivar_usage
         @blog_engine = "Not the engine route helper"
-        render :text => blog_engine.post_path(:id => 1)
+        render plain: blog_engine.post_path(id: 1)
       end
     end
 
@@ -378,7 +378,7 @@ module TestGenerationPrefix
       include RailsApplication.routes.mounted_helpers
 
       def show
-        render :text => post_path(:id => params[:id])
+        render plain: post_path(id: params[:id])
       end
     end
 
diff --git a/actionpack/test/dispatch/request/json_params_parsing_test.rb b/actionpack/test/dispatch/request/json_params_parsing_test.rb
index b765a13fa1..c2300a0142 100644
--- a/actionpack/test/dispatch/request/json_params_parsing_test.rb
+++ b/actionpack/test/dispatch/request/json_params_parsing_test.rb
@@ -56,7 +56,7 @@ class JsonParamsParsingTest < ActionDispatch::IntegrationTest
     with_test_routing do
       output = StringIO.new
       json = "[\"person]\": {\"name\": \"David\"}}"
-      post "/parse", json, {'CONTENT_TYPE' => 'application/json', 'action_dispatch.show_exceptions' => true, 'action_dispatch.logger' => ActiveSupport::Logger.new(output)}
+      post "/parse", params: json, headers: { 'CONTENT_TYPE' => 'application/json', 'action_dispatch.show_exceptions' => true, 'action_dispatch.logger' => ActiveSupport::Logger.new(output) }
       assert_response :bad_request
       output.rewind && err = output.read
       assert err =~ /Error occurred while parsing request parameters/
@@ -79,7 +79,7 @@ class JsonParamsParsingTest < ActionDispatch::IntegrationTest
 
   test 'raw_post is not empty for JSON request' do
     with_test_routing do
-      post '/parse', '{"posts": [{"title": "Post Title"}]}', 'CONTENT_TYPE' => 'application/json'
+      post '/parse', params: '{"posts": [{"title": "Post Title"}]}', headers: { 'CONTENT_TYPE' => 'application/json' }
       assert_equal '{"posts": [{"title": "Post Title"}]}', request.raw_post
     end
   end
@@ -87,7 +87,7 @@ class JsonParamsParsingTest < ActionDispatch::IntegrationTest
   private
     def assert_parses(expected, actual, headers = {})
       with_test_routing do
-        post "/parse", actual, headers
+        post "/parse", params: actual, headers: headers
         assert_response :ok
         assert_equal(expected, TestController.last_request_parameters)
       end
@@ -113,7 +113,7 @@ class RootLessJSONParamsParsingTest < ActionDispatch::IntegrationTest
 
     def parse
       self.class.last_request_parameters = request.request_parameters
-      self.class.last_parameters = params
+      self.class.last_parameters = params.to_unsafe_h
       head :ok
     end
   end
@@ -146,7 +146,7 @@ class RootLessJSONParamsParsingTest < ActionDispatch::IntegrationTest
   private
     def assert_parses(expected, actual, headers = {})
       with_test_routing(UsersController) do
-        post "/parse", actual, headers
+        post "/parse", params: actual, headers: headers
         assert_response :ok
         assert_equal(expected, UsersController.last_request_parameters)
         assert_equal(expected.merge({"action" => "parse"}), UsersController.last_parameters)
diff --git a/actionpack/test/dispatch/request/multipart_params_parsing_test.rb b/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
index 926472163e..b36fbd3c76 100644
--- a/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
+++ b/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
@@ -18,7 +17,7 @@ class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
     end
 
     def read
-      render :text => "File: #{params[:uploaded_data].read}"
+      render plain: "File: #{params[:uploaded_data].read}"
     end
   end
 
@@ -37,7 +36,7 @@ class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
   end
 
   test "parse single utf8 parameter" do
-    assert_equal({ 'Iñtërnâtiônàlizætiøn_name' => 'Iñtërnâtiônàlizætiøn_value'}, 
+    assert_equal({ 'Iñtërnâtiônàlizætiøn_name' => 'Iñtërnâtiônàlizætiøn_value'},
                  parse_multipart('single_utf8_param'), "request.request_parameters")
     assert_equal(
       'Iñtërnâtiônàlizætiøn_value',
@@ -45,8 +44,8 @@ class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
   end
 
   test "parse bracketed utf8 parameter" do
-    assert_equal({ 'Iñtërnâtiônàlizætiøn_name' => { 
-      'Iñtërnâtiônàlizætiøn_nested_name' => 'Iñtërnâtiônàlizætiøn_value'} }, 
+    assert_equal({ 'Iñtërnâtiônàlizætiøn_name' => {
+      'Iñtërnâtiônàlizætiøn_nested_name' => 'Iñtërnâtiônàlizætiøn_value'} },
       parse_multipart('bracketed_utf8_param'), "request.request_parameters")
     assert_equal(
       {'Iñtërnâtiônàlizætiøn_nested_name' => 'Iñtërnâtiônàlizætiøn_value'},
@@ -64,6 +63,17 @@ class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
     assert_equal 'contents', file.read
   end
 
+  test "parses utf8 filename with percent character" do
+    params = parse_multipart('utf8_filename')
+    assert_equal %w(file foo), params.keys.sort
+    assert_equal 'bar', params['foo']
+
+    file = params['file']
+    assert_equal 'ファイル%名.txt', file.original_filename
+    assert_equal "text/plain", file.content_type
+    assert_equal 'contents', file.read
+  end
+
   test "parses boundary problem file" do
     params = parse_multipart('boundary_problem_file')
     assert_equal %w(file foo), params.keys.sort
@@ -134,13 +144,13 @@ class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
     with_test_routing do
       fixture = FIXTURE_PATH + "/mona_lisa.jpg"
       params = { :uploaded_data => fixture_file_upload(fixture, "image/jpg") }
-      post '/read', params
+      post '/read', params: params
     end
   end
 
   test "uploads and reads file" do
     with_test_routing do
-      post '/read', :uploaded_data => fixture_file_upload(FIXTURE_PATH + "/hello.txt", "text/plain")
+      post '/read', params: { uploaded_data: fixture_file_upload(FIXTURE_PATH + "/hello.txt", "text/plain") }
       assert_equal "File: Hello", response.body
     end
   end
@@ -152,7 +162,7 @@ class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
         get ':action', controller: 'multipart_params_parsing_test/test'
       end
       headers = { "CONTENT_TYPE" => "multipart/form-data; boundary=AaB03x" }
-      get "/parse", {}, headers
+      get "/parse", headers: headers
       assert_response :ok
     end
   end
@@ -169,7 +179,7 @@ class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
     def parse_multipart(name)
       with_test_routing do
         headers = fixture(name)
-        post "/parse", headers.delete("rack.input"), headers
+        post "/parse", params: headers.delete("rack.input"), headers: headers
         assert_response :ok
         TestController.last_request_parameters
       end
diff --git a/actionpack/test/dispatch/request/query_string_parsing_test.rb b/actionpack/test/dispatch/request/query_string_parsing_test.rb
index 50daafbb54..bc6716525e 100644
--- a/actionpack/test/dispatch/request/query_string_parsing_test.rb
+++ b/actionpack/test/dispatch/request/query_string_parsing_test.rb
@@ -147,7 +147,7 @@ class QueryStringParsingTest < ActionDispatch::IntegrationTest
         get ':action', :to => ::QueryStringParsingTest::TestController
       end
 
-      get "/parse", nil, "QUERY_STRING" => "foo[]=bar&foo[4]=bar"
+      get "/parse", headers: { "QUERY_STRING" => "foo[]=bar&foo[4]=bar" }
       assert_response :bad_request
     end
   end
@@ -162,8 +162,7 @@ class QueryStringParsingTest < ActionDispatch::IntegrationTest
           middleware.use(EarlyParse)
         end
 
-
-        get "/parse", actual
+        get "/parse", params: actual
         assert_response :ok
         assert_equal(expected, ::QueryStringParsingTest::TestController.last_query_parameters)
       end
diff --git a/actionpack/test/dispatch/request/session_test.rb b/actionpack/test/dispatch/request/session_test.rb
index 10fb04e230..ae0e7e93ed 100644
--- a/actionpack/test/dispatch/request/session_test.rb
+++ b/actionpack/test/dispatch/request/session_test.rb
@@ -4,40 +4,42 @@ require 'action_dispatch/middleware/session/abstract_store'
 module ActionDispatch
   class Request
     class SessionTest < ActiveSupport::TestCase
+      attr_reader :req
+
+      def setup
+        @req = ActionDispatch::Request.new({})
+      end
+
       def test_create_adds_itself_to_env
-        env = {}
-        s = Session.create(store, env, {})
-        assert_equal s, env[Rack::Session::Abstract::ENV_SESSION_KEY]
+        s = Session.create(store, req, {})
+        assert_equal s, req.env[Rack::RACK_SESSION]
       end
 
       def test_to_hash
-        env = {}
-        s = Session.create(store, env, {})
+        s = Session.create(store, req, {})
         s['foo'] = 'bar'
         assert_equal 'bar', s['foo']
         assert_equal({'foo' => 'bar'}, s.to_hash)
       end
 
       def test_create_merges_old
-        env = {}
-        s = Session.create(store, env, {})
+        s = Session.create(store, req, {})
         s['foo'] = 'bar'
 
-        s1 = Session.create(store, env, {})
+        s1 = Session.create(store, req, {})
         assert_not_equal s, s1
         assert_equal 'bar', s1['foo']
       end
 
       def test_find
-        env = {}
-        assert_nil Session.find(env)
+        assert_nil Session.find(req)
 
-        s = Session.create(store, env, {})
-        assert_equal s, Session.find(env)
+        s = Session.create(store, req, {})
+        assert_equal s, Session.find(req)
       end
 
       def test_destroy
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
 
         s.destroy
@@ -46,21 +48,21 @@ module ActionDispatch
       end
 
       def test_keys
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
         s['adequate'] = 'awesome'
         assert_equal %w[rails adequate], s.keys
       end
 
       def test_values
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
         s['adequate'] = 'awesome'
         assert_equal %w[ftw awesome], s.values
       end
 
       def test_clear
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
         s['adequate'] = 'awesome'
 
@@ -69,7 +71,7 @@ module ActionDispatch
       end
 
       def test_update
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
 
         s.update(:rails => 'awesome')
@@ -79,7 +81,7 @@ module ActionDispatch
       end
 
       def test_delete
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
 
         s.delete('rails')
@@ -88,7 +90,7 @@ module ActionDispatch
       end
 
       def test_fetch
-        session = Session.create(store, {}, {})
+        session = Session.create(store, req, {})
 
         session['one'] = '1'
         assert_equal '1', session.fetch(:one)
@@ -108,7 +110,7 @@ module ActionDispatch
         Class.new {
           def load_session(env); [1, {}]; end
           def session_exists?(env); true; end
-          def destroy_session(env, id, options); 123; end
+          def delete_session(env, id, options); 123; end
         }.new
       end
     end
diff --git a/actionpack/test/dispatch/request/url_encoded_params_parsing_test.rb b/actionpack/test/dispatch/request/url_encoded_params_parsing_test.rb
index 1de05cbf09..365edf849a 100644
--- a/actionpack/test/dispatch/request/url_encoded_params_parsing_test.rb
+++ b/actionpack/test/dispatch/request/url_encoded_params_parsing_test.rb
@@ -131,7 +131,7 @@ class UrlEncodedParamsParsingTest < ActionDispatch::IntegrationTest
 
   test "ambiguous params returns a bad request" do
     with_test_routing do
-      post "/parse", "foo[]=bar&foo[4]=bar"
+      post "/parse", params: "foo[]=bar&foo[4]=bar"
       assert_response :bad_request
     end
   end
@@ -148,7 +148,7 @@ class UrlEncodedParamsParsingTest < ActionDispatch::IntegrationTest
 
     def assert_parses(expected, actual)
       with_test_routing do
-        post "/parse", actual
+        post "/parse", params: actual
         assert_response :ok
         assert_equal expected, TestController.last_request_parameters
         assert_utf8 TestController.last_request_parameters
diff --git a/actionpack/test/dispatch/request_id_test.rb b/actionpack/test/dispatch/request_id_test.rb
index a8050b4fab..00d8caf8f4 100644
--- a/actionpack/test/dispatch/request_id_test.rb
+++ b/actionpack/test/dispatch/request_id_test.rb
@@ -2,19 +2,23 @@ require 'abstract_unit'
 
 class RequestIdTest < ActiveSupport::TestCase
   test "passing on the request id from the outside" do
-    assert_equal "external-uu-rid", stub_request('HTTP_X_REQUEST_ID' => 'external-uu-rid').uuid
+    assert_equal "external-uu-rid", stub_request('HTTP_X_REQUEST_ID' => 'external-uu-rid').request_id
   end
 
   test "ensure that only alphanumeric uurids are accepted" do
-    assert_equal "X-Hacked-HeaderStuff", stub_request('HTTP_X_REQUEST_ID' => '; X-Hacked-Header: Stuff').uuid
+    assert_equal "X-Hacked-HeaderStuff", stub_request('HTTP_X_REQUEST_ID' => '; X-Hacked-Header: Stuff').request_id
   end
 
   test "ensure that 255 char limit on the request id is being enforced" do
-    assert_equal "X" * 255, stub_request('HTTP_X_REQUEST_ID' => 'X' * 500).uuid
+    assert_equal "X" * 255, stub_request('HTTP_X_REQUEST_ID' => 'X' * 500).request_id
   end
 
   test "generating a request id when none is supplied" do
-    assert_match(/\w+-\w+-\w+-\w+-\w+/, stub_request.uuid)
+    assert_match(/\w+-\w+-\w+-\w+-\w+/, stub_request.request_id)
+  end
+
+  test "uuid alias" do
+    assert_equal "external-uu-rid", stub_request('HTTP_X_REQUEST_ID' => 'external-uu-rid').uuid
   end
 
   private
@@ -41,7 +45,7 @@ class RequestIdResponseTest < ActionDispatch::IntegrationTest
 
   test "request id given on request is passed all the way to the response" do
     with_test_route_set do
-      get '/', {}, 'HTTP_X_REQUEST_ID' => 'X' * 500
+      get '/', headers: { 'HTTP_X_REQUEST_ID' => 'X' * 500 }
       assert_equal "X" * 255, @response.headers["X-Request-Id"]
     end
   end
diff --git a/actionpack/test/dispatch/request_test.rb b/actionpack/test/dispatch/request_test.rb
index ee8e915610..e9896a71f4 100644
--- a/actionpack/test/dispatch/request_test.rb
+++ b/actionpack/test/dispatch/request_test.rb
@@ -435,6 +435,9 @@ class RequestHost < BaseRequestTest
 
     request = stub_request 'HTTP_X_FORWARDED_HOST' => "www.firsthost.org, www.secondhost.org"
     assert_equal "www.secondhost.org", request.host
+
+    request = stub_request 'HTTP_X_FORWARDED_HOST' => "", 'HTTP_HOST' => "rubyonrails.org"
+    assert_equal "rubyonrails.org", request.host
   end
 
   test "http host with default port overrides server port" do
@@ -660,6 +663,7 @@ class RequestMethod < BaseRequestTest
 
     assert_equal 'GET', request.request_method
     assert_equal 'GET', request.env["REQUEST_METHOD"]
+    assert request.get?
   end
 
   test "invalid http method raises exception" do
@@ -745,84 +749,94 @@ end
 class RequestFormat < BaseRequestTest
   test "xml format" do
     request = stub_request
-    request.expects(:parameters).at_least_once.returns({ :format => 'xml' })
-    assert_equal Mime::XML, request.format
+    assert_called(request, :parameters, times: 2, returns: {format: :xml}) do
+      assert_equal Mime[:xml], request.format
+    end
   end
 
   test "xhtml format" do
     request = stub_request
-    request.expects(:parameters).at_least_once.returns({ :format => 'xhtml' })
-    assert_equal Mime::HTML, request.format
+    assert_called(request, :parameters, times: 2, returns: {format: :xhtml}) do
+      assert_equal Mime[:html], request.format
+    end
   end
 
   test "txt format" do
     request = stub_request
-    request.expects(:parameters).at_least_once.returns({ :format => 'txt' })
-    assert_equal Mime::TEXT, request.format
+    assert_called(request, :parameters, times: 2, returns: {format: :txt}) do
+      assert_equal Mime[:text], request.format
+    end
   end
 
   test "XMLHttpRequest" do
     request = stub_request(
       'HTTP_X_REQUESTED_WITH' => 'XMLHttpRequest',
-      'HTTP_ACCEPT' => [Mime::JS, Mime::HTML, Mime::XML, "text/xml", Mime::ALL].join(",")
+      'HTTP_ACCEPT' => [Mime[:js], Mime[:html], Mime[:xml], "text/xml", "*/*"].join(",")
     )
-    request.expects(:parameters).at_least_once.returns({})
-    assert request.xhr?
-    assert_equal Mime::JS, request.format
+
+    assert_called(request, :parameters, times: 1, returns: {}) do
+      assert request.xhr?
+      assert_equal Mime[:js], request.format
+    end
   end
 
   test "can override format with parameter negative" do
     request = stub_request
-    request.expects(:parameters).at_least_once.returns({ :format => :txt })
-    assert !request.format.xml?
+    assert_called(request, :parameters, times: 2, returns: {format: :txt}) do
+      assert !request.format.xml?
+    end
   end
 
   test "can override format with parameter positive" do
     request = stub_request
-    request.expects(:parameters).at_least_once.returns({ :format => :xml })
-    assert request.format.xml?
+    assert_called(request, :parameters, times: 2, returns: {format: :xml}) do
+      assert request.format.xml?
+    end
   end
 
   test "formats text/html with accept header" do
     request = stub_request 'HTTP_ACCEPT' => 'text/html'
-    assert_equal [Mime::HTML], request.formats
+    assert_equal [Mime[:html]], request.formats
   end
 
   test "formats blank with accept header" do
     request = stub_request 'HTTP_ACCEPT' => ''
-    assert_equal [Mime::HTML], request.formats
+    assert_equal [Mime[:html]], request.formats
   end
 
   test "formats XMLHttpRequest with accept header" do
     request = stub_request 'HTTP_X_REQUESTED_WITH' => "XMLHttpRequest"
-    assert_equal [Mime::JS], request.formats
+    assert_equal [Mime[:js]], request.formats
   end
 
   test "formats application/xml with accept header" do
     request = stub_request('CONTENT_TYPE' => 'application/xml; charset=UTF-8',
                            'HTTP_X_REQUESTED_WITH' => "XMLHttpRequest")
-    assert_equal [Mime::XML], request.formats
+    assert_equal [Mime[:xml]], request.formats
   end
 
   test "formats format:text with accept header" do
     request = stub_request
-    request.expects(:parameters).at_least_once.returns({ :format => :txt })
-    assert_equal [Mime::TEXT], request.formats
+    assert_called(request, :parameters, times: 2, returns: {format: :txt}) do
+      assert_equal [Mime[:text]], request.formats
+    end
   end
 
   test "formats format:unknown with accept header" do
     request = stub_request
-    request.expects(:parameters).at_least_once.returns({ :format => :unknown })
-    assert_instance_of Mime::NullType, request.format
+    assert_called(request, :parameters, times: 2, returns: {format: :unknown}) do
+      assert_instance_of Mime::NullType, request.format
+    end
   end
 
   test "format is not nil with unknown format" do
     request = stub_request
-    request.expects(:parameters).at_least_once.returns({ format: :hello })
-    assert request.format.nil?
-    assert_not request.format.html?
-    assert_not request.format.xml?
-    assert_not request.format.json?
+    assert_called(request, :parameters, times: 2, returns: {format: :hello}) do
+      assert request.format.nil?
+      assert_not request.format.html?
+      assert_not request.format.xml?
+      assert_not request.format.json?
+    end
   end
 
   test "format does not throw exceptions when malformed parameters" do
@@ -833,8 +847,9 @@ class RequestFormat < BaseRequestTest
 
   test "formats with xhr request" do
     request = stub_request 'HTTP_X_REQUESTED_WITH' => "XMLHttpRequest"
-    request.expects(:parameters).at_least_once.returns({})
-    assert_equal [Mime::JS], request.formats
+    assert_called(request, :parameters, times: 1, returns: {}) do
+      assert_equal [Mime[:js]], request.formats
+    end
   end
 
   test "ignore_accept_header" do
@@ -843,30 +858,37 @@ class RequestFormat < BaseRequestTest
 
     begin
       request = stub_request 'HTTP_ACCEPT' => 'application/xml'
-      request.expects(:parameters).at_least_once.returns({})
-      assert_equal [ Mime::HTML ], request.formats
+      assert_called(request, :parameters, times: 1, returns: {}) do
+        assert_equal [ Mime[:html] ], request.formats
+      end
 
       request = stub_request 'HTTP_ACCEPT' => 'koz-asked/something-crazy'
-      request.expects(:parameters).at_least_once.returns({})
-      assert_equal [ Mime::HTML ], request.formats
+      assert_called(request, :parameters, times: 1, returns: {}) do
+        assert_equal [ Mime[:html] ], request.formats
+      end
 
       request = stub_request 'HTTP_ACCEPT' => '*/*;q=0.1'
-      request.expects(:parameters).at_least_once.returns({})
-      assert_equal [ Mime::HTML ], request.formats
+      assert_called(request, :parameters, times: 1, returns: {}) do
+        assert_equal [ Mime[:html] ], request.formats
+      end
 
       request = stub_request 'HTTP_ACCEPT' => 'application/jxw'
-      request.expects(:parameters).at_least_once.returns({})
-      assert_equal [ Mime::HTML ], request.formats
+      assert_called(request, :parameters, times: 1, returns: {}) do
+        assert_equal [ Mime[:html] ], request.formats
+      end
 
       request = stub_request 'HTTP_ACCEPT' => 'application/xml',
                              'HTTP_X_REQUESTED_WITH' => "XMLHttpRequest"
-      request.expects(:parameters).at_least_once.returns({})
-      assert_equal [ Mime::JS ], request.formats
+
+      assert_called(request, :parameters, times: 1, returns: {}) do
+        assert_equal [ Mime[:js] ], request.formats
+      end
 
       request = stub_request 'HTTP_ACCEPT' => 'application/xml',
                              'HTTP_X_REQUESTED_WITH' => "XMLHttpRequest"
-      request.expects(:parameters).at_least_once.returns({:format => :json})
-      assert_equal [ Mime::JSON ], request.formats
+      assert_called(request, :parameters, times: 2, returns: {format: :json}) do
+        assert_equal [ Mime[:json] ], request.formats
+      end
     ensure
       ActionDispatch::Request.ignore_accept_header = old_ignore_accept_header
     end
@@ -875,7 +897,7 @@ end
 
 class RequestMimeType < BaseRequestTest
   test "content type" do
-    assert_equal Mime::HTML, stub_request('CONTENT_TYPE' => 'text/html').content_mime_type
+    assert_equal Mime[:html], stub_request('CONTENT_TYPE' => 'text/html').content_mime_type
   end
 
   test "no content type" do
@@ -883,11 +905,11 @@ class RequestMimeType < BaseRequestTest
   end
 
   test "content type is XML" do
-    assert_equal Mime::XML, stub_request('CONTENT_TYPE' => 'application/xml').content_mime_type
+    assert_equal Mime[:xml], stub_request('CONTENT_TYPE' => 'application/xml').content_mime_type
   end
 
   test "content type with charset" do
-    assert_equal Mime::XML, stub_request('CONTENT_TYPE' => 'application/xml; charset=UTF-8').content_mime_type
+    assert_equal Mime[:xml], stub_request('CONTENT_TYPE' => 'application/xml; charset=UTF-8').content_mime_type
   end
 
   test "user agent" do
@@ -900,9 +922,9 @@ class RequestMimeType < BaseRequestTest
       'HTTP_X_REQUESTED_WITH' => "XMLHttpRequest"
     )
 
-    assert_equal nil, request.negotiate_mime([Mime::XML, Mime::JSON])
-    assert_equal Mime::HTML, request.negotiate_mime([Mime::XML, Mime::HTML])
-    assert_equal Mime::HTML, request.negotiate_mime([Mime::XML, Mime::ALL])
+    assert_equal nil, request.negotiate_mime([Mime[:xml], Mime[:json]])
+    assert_equal Mime[:html], request.negotiate_mime([Mime[:xml], Mime[:html]])
+    assert_equal Mime[:html], request.negotiate_mime([Mime[:xml], Mime::ALL])
   end
 
   test "negotiate_mime with content_type" do
@@ -911,19 +933,21 @@ class RequestMimeType < BaseRequestTest
       'HTTP_X_REQUESTED_WITH' => "XMLHttpRequest"
     )
 
-    assert_equal Mime::XML, request.negotiate_mime([Mime::XML, Mime::CSV])
+    assert_equal Mime[:xml], request.negotiate_mime([Mime[:xml], Mime[:csv]])
   end
 end
 
 class RequestParameters < BaseRequestTest
   test "parameters" do
     request = stub_request
-    request.expects(:request_parameters).at_least_once.returns({ "foo" => 1 })
-    request.expects(:query_parameters).at_least_once.returns({ "bar" => 2 })
 
-    assert_equal({"foo" => 1, "bar" => 2}, request.parameters)
-    assert_equal({"foo" => 1}, request.request_parameters)
-    assert_equal({"bar" => 2}, request.query_parameters)
+    assert_called(request, :request_parameters, times: 2, returns: {"foo" => 1}) do
+      assert_called(request, :query_parameters, times: 2, returns: {"bar" => 2}) do
+        assert_equal({"foo" => 1, "bar" => 2}, request.parameters)
+        assert_equal({"foo" => 1}, request.request_parameters)
+        assert_equal({"bar" => 2}, request.query_parameters)
+      end
+    end
   end
 
   test "parameters not accessible after rack parse error" do
@@ -937,15 +961,33 @@ class RequestParameters < BaseRequestTest
     end
   end
 
+  test "path parameters with invalid UTF8 encoding" do
+    request = stub_request(
+      "action_dispatch.request.path_parameters" => { foo: "\xBE" }
+    )
+
+    err = assert_raises(ActionController::BadRequest) do
+      request.check_path_parameters!
+    end
+
+    assert_match "Invalid parameter encoding", err.message
+    assert_match "foo", err.message
+    assert_match "\\xBE", err.message
+  end
+
   test "parameters not accessible after rack parse error of invalid UTF8 character" do
     request = stub_request("QUERY_STRING" => "foo%81E=1")
+    assert_raises(ActionController::BadRequest) { request.parameters }
+  end
 
-    2.times do
-      assert_raises(ActionController::BadRequest) do
-        # rack will raise a Rack::Utils::InvalidParameterError when parsing this query string
-        request.parameters
-      end
-    end
+  test "parameters containing an invalid UTF8 character" do
+    request = stub_request("QUERY_STRING" => "foo=%81E")
+    assert_raises(ActionController::BadRequest) { request.parameters }
+  end
+
+  test "parameters containing a deeply nested invalid UTF8 character" do
+    request = stub_request("QUERY_STRING" => "foo[bar]=%81E")
+    assert_raises(ActionController::BadRequest) { request.parameters }
   end
 
   test "parameters not accessible after rack parse error 1" do
@@ -985,6 +1027,7 @@ class RequestParameterFilter < BaseRequestTest
     [{'foo'=>'bar', 'baz'=>'foo'},{'foo'=>'[FILTERED]', 'baz'=>'[FILTERED]'},%w'foo baz'],
     [{'bar'=>{'foo'=>'bar','bar'=>'foo'}},{'bar'=>{'foo'=>'[FILTERED]','bar'=>'foo'}},%w'fo'],
     [{'foo'=>{'foo'=>'bar','bar'=>'foo'}},{'foo'=>'[FILTERED]'},%w'f banana'],
+    [{'deep'=>{'cc'=>{'code'=>'bar','bar'=>'foo'},'ss'=>{'code'=>'bar'}}},{'deep'=>{'cc'=>{'code'=>'[FILTERED]','bar'=>'foo'},'ss'=>{'code'=>'bar'}}},%w'deep.cc.code'],
     [{'baz'=>[{'foo'=>'baz'}, "1"]}, {'baz'=>[{'foo'=>'[FILTERED]'}, "1"]}, [/foo/]]]
 
     test_hashes.each do |before_filter, after_filter, filter_words|
@@ -1125,35 +1168,47 @@ class RequestEtag < BaseRequestTest
 end
 
 class RequestVariant < BaseRequestTest
-  test "setting variant" do
-    request = stub_request
+  def setup
+    super
+    @request = stub_request
+  end
 
-    request.variant = :mobile
-    assert_equal [:mobile], request.variant
+  test 'setting variant to a symbol' do
+    @request.variant = :phone
 
-    request.variant = [:phone, :tablet]
-    assert_equal [:phone, :tablet], request.variant
+    assert @request.variant.phone?
+    assert_not @request.variant.tablet?
+    assert @request.variant.any?(:phone, :tablet)
+    assert_not @request.variant.any?(:tablet, :desktop)
+  end
 
-    assert_raise ArgumentError do
-      request.variant = [:phone, "tablet"]
-    end
+  test 'setting variant to an array of symbols' do
+    @request.variant = [:phone, :tablet]
 
-    assert_raise ArgumentError do
-      request.variant = "yolo"
-    end
+    assert @request.variant.phone?
+    assert @request.variant.tablet?
+    assert_not @request.variant.desktop?
+    assert @request.variant.any?(:tablet, :desktop)
+    assert_not @request.variant.any?(:desktop, :watch)
   end
 
-  test "reset variant" do
-    request = stub_request
+  test 'clearing variant' do
+    @request.variant = nil
 
-    request.variant = nil
-    assert_equal nil, request.variant
+    assert @request.variant.empty?
+    assert_not @request.variant.phone?
+    assert_not @request.variant.any?(:phone, :tablet)
   end
 
-  test "setting variant with non symbol value" do
-    request = stub_request
+  test 'setting variant to a non-symbol value' do
+    assert_raise ArgumentError do
+      @request.variant = 'phone'
+    end
+  end
+
+  test 'setting variant to an array containing a non-symbol value' do
     assert_raise ArgumentError do
-      request.variant = "mobile"
+      @request.variant = [:phone, 'tablet']
     end
   end
 end
diff --git a/actionpack/test/dispatch/response_test.rb b/actionpack/test/dispatch/response_test.rb
index c61423dce4..981d820ccf 100644
--- a/actionpack/test/dispatch/response_test.rb
+++ b/actionpack/test/dispatch/response_test.rb
@@ -4,7 +4,7 @@ require 'rack/content_length'
 
 class ResponseTest < ActiveSupport::TestCase
   def setup
-    @response = ActionDispatch::Response.new
+    @response = ActionDispatch::Response.create
   end
 
   def test_can_wait_until_commit
@@ -42,6 +42,18 @@ class ResponseTest < ActiveSupport::TestCase
     assert_equal Encoding::UTF_8, response.body.encoding
   end
 
+  def test_response_charset_writer
+    @response.charset = 'utf-16'
+    assert_equal 'utf-16', @response.charset
+    @response.charset = nil
+    assert_equal 'utf-8', @response.charset
+  end
+
+  def test_setting_content_type_header_impacts_content_type_method
+    @response.headers['Content-Type'] = "application/aaron"
+    assert_equal 'application/aaron', @response.content_type
+  end
+
   test "simple output" do
     @response.body = "Hello, World!"
 
@@ -60,6 +72,13 @@ class ResponseTest < ActiveSupport::TestCase
     assert_equal 200, ActionDispatch::Response.new('200 OK').status
   end
 
+  def test_only_set_charset_still_defaults_to_text_html
+    response = ActionDispatch::Response.new
+    response.charset = "utf-16"
+    _,headers,_ = response.to_a
+    assert_equal "text/html; charset=utf-16", headers['Content-Type']
+  end
+
   test "utf8 output" do
     @response.body = [1090, 1077, 1089, 1090].pack("U*")
 
@@ -72,12 +91,14 @@ class ResponseTest < ActiveSupport::TestCase
 
   test "content type" do
     [204, 304].each do |c|
+      @response = ActionDispatch::Response.new
       @response.status = c.to_s
       _, headers, _ = @response.to_a
       assert !headers.has_key?("Content-Type"), "#{c} should not have Content-Type header"
     end
 
     [200, 302, 404, 500].each do |c|
+      @response = ActionDispatch::Response.new
       @response.status = c.to_s
       _, headers, _ = @response.to_a
       assert headers.has_key?("Content-Type"), "#{c} did not have Content-Type header"
@@ -125,17 +146,23 @@ class ResponseTest < ActiveSupport::TestCase
 
   test "cookies" do
     @response.set_cookie("user_name", :value => "david", :path => "/")
-    status, headers, body = @response.to_a
+    _status, headers, _body = @response.to_a
     assert_equal "user_name=david; path=/", headers["Set-Cookie"]
     assert_equal({"user_name" => "david"}, @response.cookies)
+  end
 
+  test "multiple cookies" do
+    @response.set_cookie("user_name", :value => "david", :path => "/")
     @response.set_cookie("login", :value => "foo&bar", :path => "/", :expires => Time.utc(2005, 10, 10,5))
-    status, headers, body = @response.to_a
+    _status, headers, _body = @response.to_a
     assert_equal "user_name=david; path=/\nlogin=foo%26bar; path=/; expires=Mon, 10 Oct 2005 05:00:00 -0000", headers["Set-Cookie"]
     assert_equal({"login" => "foo&bar", "user_name" => "david"}, @response.cookies)
+  end
 
+  test "delete cookies" do
+    @response.set_cookie("user_name", :value => "david", :path => "/")
+    @response.set_cookie("login", :value => "foo&bar", :path => "/", :expires => Time.utc(2005, 10, 10,5))
     @response.delete_cookie("login")
-    status, headers, body = @response.to_a
     assert_equal({"user_name" => "david", "login" => nil}, @response.cookies)
   end
 
@@ -157,18 +184,28 @@ class ResponseTest < ActiveSupport::TestCase
   test "read charset and content type" do
     resp = ActionDispatch::Response.new.tap { |response|
       response.charset = 'utf-16'
-      response.content_type = Mime::XML
+      response.content_type = Mime[:xml]
       response.body = 'Hello'
     }
     resp.to_a
 
     assert_equal('utf-16', resp.charset)
-    assert_equal(Mime::XML, resp.content_type)
+    assert_equal(Mime[:xml], resp.content_type)
 
     assert_equal('application/xml; charset=utf-16', resp.headers['Content-Type'])
   end
 
-  test "read content type without charset" do
+  test "read content type with default charset utf-8" do
+    original = ActionDispatch::Response.default_charset
+    begin
+      resp = ActionDispatch::Response.new(200, { "Content-Type" => "text/xml" })
+      assert_equal('utf-8', resp.charset)
+    ensure
+      ActionDispatch::Response.default_charset = original
+    end
+  end
+
+  test "read content type with charset utf-16" do
     original = ActionDispatch::Response.default_charset
     begin
       ActionDispatch::Response.default_charset = 'utf-16'
@@ -187,7 +224,7 @@ class ResponseTest < ActiveSupport::TestCase
         'X-Content-Type-Options' => 'nosniff',
         'X-XSS-Protection' => '1;'
       }
-      resp = ActionDispatch::Response.new.tap { |response|
+      resp = ActionDispatch::Response.create.tap { |response|
         response.body = 'Hello'
       }
       resp.to_a
@@ -206,7 +243,7 @@ class ResponseTest < ActiveSupport::TestCase
       ActionDispatch::Response.default_headers = {
         'X-XX-XXXX' => 'Here is my phone number'
       }
-      resp = ActionDispatch::Response.new.tap { |response|
+      resp = ActionDispatch::Response.create.tap { |response|
         response.body = 'Hello'
       }
       resp.to_a
@@ -253,11 +290,66 @@ class ResponseTest < ActiveSupport::TestCase
   end
 end
 
-class ResponseIntegrationTest < ActionDispatch::IntegrationTest
-  def app
-    @app
+class ResponseHeadersTest < ActiveSupport::TestCase
+  def setup
+    @response = ActionDispatch::Response.create
+    @response.set_header 'Foo', '1'
   end
 
+  test 'has_header?' do
+    assert @response.has_header? 'Foo'
+    assert_not @response.has_header? 'foo'
+    assert_not @response.has_header? nil
+  end
+
+  test 'get_header' do
+    assert_equal '1', @response.get_header('Foo')
+    assert_nil @response.get_header('foo')
+    assert_nil @response.get_header(nil)
+  end
+
+  test 'set_header' do
+    assert_equal '2', @response.set_header('Foo', '2')
+    assert @response.has_header?('Foo')
+    assert_equal '2', @response.get_header('Foo')
+
+    assert_nil @response.set_header('Foo', nil)
+    assert @response.has_header?('Foo')
+    assert_nil @response.get_header('Foo')
+  end
+
+  test 'delete_header' do
+    assert_nil @response.delete_header(nil)
+
+    assert_nil @response.delete_header('foo')
+    assert @response.has_header?('Foo')
+
+    assert_equal '1', @response.delete_header('Foo')
+    assert_not @response.has_header?('Foo')
+  end
+
+  test 'add_header' do
+    # Add a value to an existing header
+    assert_equal '1,2', @response.add_header('Foo', '2')
+    assert_equal '1,2', @response.get_header('Foo')
+
+    # Add nil to an existing header
+    assert_equal '1,2', @response.add_header('Foo', nil)
+    assert_equal '1,2', @response.get_header('Foo')
+
+    # Add nil to a nonexistent header
+    assert_nil @response.add_header('Bar', nil)
+    assert_not @response.has_header?('Bar')
+    assert_nil @response.get_header('Bar')
+
+    # Add a value to a nonexistent header
+    assert_equal '1', @response.add_header('Bar', '1')
+    assert @response.has_header?('Bar')
+    assert_equal '1', @response.get_header('Bar')
+  end
+end
+
+class ResponseIntegrationTest < ActionDispatch::IntegrationTest
   test "response cache control from railsish app" do
     @app = lambda { |env|
       ActionDispatch::Response.new.tap { |resp|
@@ -298,7 +390,7 @@ class ResponseIntegrationTest < ActionDispatch::IntegrationTest
     @app = lambda { |env|
       ActionDispatch::Response.new.tap { |resp|
         resp.charset = 'utf-16'
-        resp.content_type = Mime::XML
+        resp.content_type = Mime[:xml]
         resp.body = 'Hello'
       }.to_a
     }
@@ -307,7 +399,7 @@ class ResponseIntegrationTest < ActionDispatch::IntegrationTest
     assert_response :success
 
     assert_equal('utf-16', @response.charset)
-    assert_equal(Mime::XML, @response.content_type)
+    assert_equal(Mime[:xml], @response.content_type)
 
     assert_equal('application/xml; charset=utf-16', @response.headers['Content-Type'])
   end
@@ -323,7 +415,7 @@ class ResponseIntegrationTest < ActionDispatch::IntegrationTest
     assert_response :success
 
     assert_equal('utf-16', @response.charset)
-    assert_equal(Mime::XML, @response.content_type)
+    assert_equal(Mime[:xml], @response.content_type)
 
     assert_equal('application/xml; charset=utf-16', @response.headers['Content-Type'])
   end
diff --git a/actionpack/test/dispatch/routing/inspector_test.rb b/actionpack/test/dispatch/routing/inspector_test.rb
index 3d3d4b74ae..a17d07c40b 100644
--- a/actionpack/test/dispatch/routing/inspector_test.rb
+++ b/actionpack/test/dispatch/routing/inspector_test.rb
@@ -12,12 +12,6 @@ module ActionDispatch
     class RoutesInspectorTest < ActiveSupport::TestCase
       def setup
         @set = ActionDispatch::Routing::RouteSet.new
-        app = ActiveSupport::OrderedOptions.new
-        app.config = ActiveSupport::OrderedOptions.new
-        app.config.assets = ActiveSupport::OrderedOptions.new
-        app.config.assets.prefix = '/sprockets'
-        Rails.stubs(:application).returns(app)
-        Rails.stubs(:env).returns("development")
       end
 
       def draw(options = {}, &block)
@@ -26,14 +20,6 @@ module ActionDispatch
         inspector.format(ActionDispatch::Routing::ConsoleFormatter.new, options[:filter]).split("\n")
       end
 
-      def test_json_regexp_converter
-        @set.draw do
-          get '/cart', :to => 'cart#show'
-        end
-        route = ActionDispatch::Routing::RouteWrapper.new(@set.routes.first)
-        assert_equal "^\\/cart(?:\\.([^\\/.?]+))?$", route.json_regexp
-      end
-
       def test_displaying_routes_for_engines
         engine = Class.new(Rails::Engine) do
           def self.inspect
@@ -91,6 +77,17 @@ module ActionDispatch
         ], output
       end
 
+      def test_articles_inspect_with_multiple_verbs
+        output = draw do
+          match 'articles/:id', to: 'articles#update', via: [:put, :patch]
+        end
+
+        assert_equal [
+          "Prefix Verb      URI Pattern             Controller#Action",
+          "       PUT|PATCH /articles/:id(.:format) articles#update"
+        ], output
+      end
+
       def test_inspect_shows_custom_assets
         output = draw do
           get '/custom/assets', :to => 'custom_assets#show'
@@ -321,6 +318,19 @@ module ActionDispatch
         assert_equal ["Prefix Verb URI Pattern            Controller#Action",
                       "       GET  /:controller(/:action) (?-mix:api\\/[^\\/]+)#:action"], output
       end
+
+      def test_inspect_routes_shows_resources_route_when_assets_disabled
+        @set = ActionDispatch::Routing::RouteSet.new
+
+        output = draw do
+          get '/cart', to: 'cart#show'
+        end
+
+        assert_equal [
+          "Prefix Verb URI Pattern     Controller#Action",
+          "  cart GET  /cart(.:format) cart#show"
+        ], output
+      end
     end
   end
 end
diff --git a/actionpack/test/dispatch/routing/ipv6_redirect_test.rb b/actionpack/test/dispatch/routing/ipv6_redirect_test.rb
new file mode 100644
index 0000000000..f1b2e8cfc7
--- /dev/null
+++ b/actionpack/test/dispatch/routing/ipv6_redirect_test.rb
@@ -0,0 +1,45 @@
+require 'abstract_unit'
+
+class IPv6IntegrationTest < ActionDispatch::IntegrationTest
+  Routes = ActionDispatch::Routing::RouteSet.new
+  include Routes.url_helpers
+
+  class ::BadRouteRequestController < ActionController::Base
+    include Routes.url_helpers
+    def index
+      render :text => foo_path
+    end
+
+    def foo
+      redirect_to :action => :index
+    end
+  end
+
+  Routes.draw do
+    get "/",    :to => 'bad_route_request#index', :as => :index
+    get "/foo", :to => "bad_route_request#foo", :as => :foo
+  end
+
+  def _routes
+    Routes
+  end
+
+  APP = build_app Routes
+  def app
+    APP
+  end
+
+  test "bad IPv6 redirection" do
+    #   def test_simple_redirect
+    request_env = {
+      'REMOTE_ADDR' => 'fd07:2fa:6cff:2112:225:90ff:fec7:22aa',
+      'HTTP_HOST'   => '[fd07:2fa:6cff:2112:225:90ff:fec7:22aa]:3000',
+      'SERVER_NAME' => '[fd07:2fa:6cff:2112:225:90ff:fec7:22aa]',
+      'SERVER_PORT' => 3000 }
+
+    get '/foo', env: request_env
+    assert_response :redirect
+    assert_equal 'http://[fd07:2fa:6cff:2112:225:90ff:fec7:22aa]:3000/', redirect_to_url
+  end
+
+end
diff --git a/actionpack/test/dispatch/routing/route_set_test.rb b/actionpack/test/dispatch/routing/route_set_test.rb
index fe52c50336..9327fe12c6 100644
--- a/actionpack/test/dispatch/routing/route_set_test.rb
+++ b/actionpack/test/dispatch/routing/route_set_test.rb
@@ -17,6 +17,16 @@ module ActionDispatch
         @set = RouteSet.new
       end
 
+      test "not being empty when route is added" do
+        assert empty?
+
+        draw do
+          get 'foo', to: SimpleApp.new('foo#index')
+        end
+
+        assert_not empty?
+      end
+
       test "url helpers are added when route is added" do
         draw do
           get 'foo', to: SimpleApp.new('foo#index')
@@ -136,6 +146,10 @@ module ActionDispatch
         def url_helpers
           @set.url_helpers
         end
+
+        def empty?
+          @set.empty?
+        end
     end
   end
 end
diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index 450681c356..8972f3e74d 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -1,4 +1,3 @@
-# encoding: UTF-8
 require 'erb'
 require 'abstract_unit'
 require 'controller/fake_controllers'
@@ -167,6 +166,44 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
     assert_equal '/session/reset', reset_session_path
   end
 
+  def test_session_singleton_resource_for_api_app
+    config = ActionDispatch::Routing::RouteSet::Config.new
+    config.api_only = true
+
+    self.class.stub_controllers(config) do |routes|
+      routes.draw do
+        resource :session do
+          get :create
+          post :reset
+        end
+      end
+      @app = RoutedRackApp.new routes
+    end
+
+    get '/session'
+    assert_equal 'sessions#create', @response.body
+    assert_equal '/session', session_path
+
+    post '/session'
+    assert_equal 'sessions#create', @response.body
+
+    put '/session'
+    assert_equal 'sessions#update', @response.body
+
+    delete '/session'
+    assert_equal 'sessions#destroy', @response.body
+
+    post '/session/reset'
+    assert_equal 'sessions#reset', @response.body
+    assert_equal '/session/reset', reset_session_path
+
+    get '/session/new'
+    assert_equal 'Not Found', @response.body
+
+    get '/session/edit'
+    assert_equal 'Not Found', @response.body
+  end
+
   def test_session_info_nested_singleton_resource
     draw do
       resource :session do
@@ -323,9 +360,12 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
   end
 
   def test_pagemarks
+    tc = self
     draw do
       scope "pagemark", :controller => "pagemarks", :as => :pagemark do
-        get  "new", :path => "build"
+        tc.assert_deprecated do
+          get  "new", :path => "build"
+        end
         post "create", :as => ""
         put  "update"
         get  "remove", :action => :destroy, :as => :remove
@@ -362,22 +402,22 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
       get 'admin/passwords' => "queenbee#passwords", :constraints => ::TestRoutingMapper::IpRestrictor
     end
 
-    get '/admin', {}, {'REMOTE_ADDR' => '192.168.1.100'}
+    get '/admin', headers: { 'REMOTE_ADDR' => '192.168.1.100' }
     assert_equal 'queenbee#index', @response.body
 
-    get '/admin', {}, {'REMOTE_ADDR' => '10.0.0.100'}
+    get '/admin', headers: { 'REMOTE_ADDR' => '10.0.0.100' }
     assert_equal 'pass', @response.headers['X-Cascade']
 
-    get '/admin/accounts', {}, {'REMOTE_ADDR' => '192.168.1.100'}
+    get '/admin/accounts', headers: { 'REMOTE_ADDR' => '192.168.1.100' }
     assert_equal 'queenbee#accounts', @response.body
 
-    get '/admin/accounts', {}, {'REMOTE_ADDR' => '10.0.0.100'}
+    get '/admin/accounts', headers: { 'REMOTE_ADDR' => '10.0.0.100' }
     assert_equal 'pass', @response.headers['X-Cascade']
 
-    get '/admin/passwords', {}, {'REMOTE_ADDR' => '192.168.1.100'}
+    get '/admin/passwords', headers: { 'REMOTE_ADDR' => '192.168.1.100' }
     assert_equal 'queenbee#passwords', @response.body
 
-    get '/admin/passwords', {}, {'REMOTE_ADDR' => '10.0.0.100'}
+    get '/admin/passwords', headers: { 'REMOTE_ADDR' => '10.0.0.100' }
     assert_equal 'pass', @response.headers['X-Cascade']
   end
 
@@ -509,6 +549,40 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
     assert_equal '/projects/1/edit', edit_project_path(:id => '1')
   end
 
+  def test_projects_for_api_app
+    config = ActionDispatch::Routing::RouteSet::Config.new
+    config.api_only = true
+
+    self.class.stub_controllers(config) do |routes|
+      routes.draw do
+        resources :projects, controller: :project
+      end
+      @app = RoutedRackApp.new routes
+    end
+
+    get '/projects'
+    assert_equal 'project#index', @response.body
+    assert_equal '/projects', projects_path
+
+    post '/projects'
+    assert_equal 'project#create', @response.body
+
+    get '/projects.xml'
+    assert_equal 'project#index', @response.body
+    assert_equal '/projects.xml', projects_path(format: 'xml')
+
+    get '/projects/1'
+    assert_equal 'project#show', @response.body
+    assert_equal '/projects/1', project_path(id: '1')
+
+    get '/projects/1.xml'
+    assert_equal 'project#show', @response.body
+    assert_equal '/projects/1.xml', project_path(id: '1', format: 'xml')
+
+    get '/projects/1/edit'
+    assert_equal 'Not Found', @response.body
+  end
+
   def test_projects_with_post_action_and_new_path_on_collection
     draw do
       resources :projects, :controller => :project do
@@ -1430,6 +1504,15 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
     assert_equal 'api/v3/products#list', @response.body
   end
 
+  def test_not_matching_shorthand_with_dynamic_parameters
+    draw do
+      get ':controller/:action/admin'
+    end
+
+    get '/finances/overview/admin'
+    assert_equal 'finances#overview', @response.body
+  end
+
   def test_controller_option_with_nesting_and_leading_slash
     draw do
       scope '/job', controller: 'job' do
@@ -1683,9 +1766,9 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
     get '/products/0001/images/0001'
     assert_equal 'images#show', @response.body
 
-    get '/dashboard', {}, {'REMOTE_ADDR' => '10.0.0.100'}
+    get '/dashboard', headers: { 'REMOTE_ADDR' => '10.0.0.100' }
     assert_equal 'pass', @response.headers['X-Cascade']
-    get '/dashboard', {}, {'REMOTE_ADDR' => '192.168.1.100'}
+    get '/dashboard', headers: { 'REMOTE_ADDR' => '192.168.1.100' }
     assert_equal 'dashboards#show', @response.body
   end
 
@@ -3439,6 +3522,62 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
     assert_equal '/bar/comments/1', comment_path('1')
   end
 
+  def test_resource_where_as_is_empty
+    draw do
+      resource :post, as: ''
+
+      scope 'post', as: 'post' do
+        resource :comment, as: ''
+      end
+    end
+
+    assert_equal '/post/new', new_path
+    assert_equal '/post/comment/new', new_post_path
+  end
+
+  def test_resources_where_as_is_empty
+    draw do
+      resources :posts, as: ''
+
+      scope 'posts', as: 'posts' do
+        resources :comments, as: ''
+      end
+    end
+
+    assert_equal '/posts/new', new_path
+    assert_equal '/posts/comments/new', new_posts_path
+  end
+
+  def test_scope_where_as_is_empty
+    draw do
+      scope 'post', as: '' do
+        resource :user
+        resources :comments
+      end
+    end
+
+    assert_equal '/post/user/new', new_user_path
+    assert_equal '/post/comments/new', new_comment_path
+  end
+
+  def test_head_fetch_with_mount_on_root
+    draw do
+      get '/home' => 'test#index'
+      mount lambda { |env| [200, {}, [env['REQUEST_METHOD']]] }, at: '/'
+    end
+
+    # HEAD request should match `get /home` rather than the
+    # lower-precedence Rack app mounted at `/`.
+    head '/home'
+    assert_response :ok
+    assert_equal 'test#index', @response.body
+
+    # But the Rack app can still respond to its own HEAD requests.
+    head '/foobar'
+    assert_response :ok
+    assert_equal 'HEAD', @response.body
+  end
+
 private
 
   def draw(&block)
@@ -3481,7 +3620,7 @@ private
 end
 
 class TestAltApp < ActionDispatch::IntegrationTest
-  class AltRequest
+  class AltRequest < ActionDispatch::Request
     attr_accessor :path_parameters, :path_info, :script_name
     attr_reader :env
 
@@ -3490,6 +3629,7 @@ class TestAltApp < ActionDispatch::IntegrationTest
       @env = env
       @path_info = "/"
       @script_name = ""
+      super
     end
 
     def request_method
@@ -3517,7 +3657,11 @@ class TestAltApp < ActionDispatch::IntegrationTest
     end
   end
 
-  AltRoutes = ActionDispatch::Routing::RouteSet.new(AltRequest)
+  AltRoutes = Class.new(ActionDispatch::Routing::RouteSet) {
+    def request_class
+      AltRequest
+    end
+  }.new
   AltRoutes.draw do
     get "/" => TestAltApp::XHeader.new, :constraints => {:x_header => /HEADER/}
     get "/" => TestAltApp::AltApp.new
@@ -3535,12 +3679,12 @@ class TestAltApp < ActionDispatch::IntegrationTest
   end
 
   def test_alt_request_with_matched_header
-    get "/", {}, "HTTP_X_HEADER" => "HEADER"
+    get "/", headers: { "HTTP_X_HEADER" => "HEADER" }
     assert_equal "XHeader", @response.body
   end
 
   def test_alt_request_with_unmatched_header
-    get "/", {}, "HTTP_X_HEADER" => "NON_MATCH"
+    get "/", headers: { "HTTP_X_HEADER" => "NON_MATCH" }
     assert_equal "Alternative App", @response.body
   end
 end
@@ -3585,7 +3729,7 @@ class TestNamespaceWithControllerOption < ActionDispatch::IntegrationTest
   module ::Admin
     class StorageFilesController < ActionController::Base
       def index
-        render :text => "admin/storage_files#index"
+        render plain: "admin/storage_files#index"
       end
     end
   end
@@ -3680,7 +3824,7 @@ class TestDefaultScope < ActionDispatch::IntegrationTest
   module ::Blog
     class PostsController < ActionController::Base
       def index
-        render :text => "blog/posts#index"
+        render plain: "blog/posts#index"
       end
     end
   end
@@ -3735,7 +3879,7 @@ class TestHttpMethods < ActionDispatch::IntegrationTest
 
   (RFC2616 + RFC2518 + RFC3253 + RFC3648 + RFC3744 + RFC5323 + RFC4791 + RFC5789).each do |method|
     test "request method #{method.underscore} can be matched" do
-      get '/', nil, 'REQUEST_METHOD' => method
+      get '/', headers: { 'REQUEST_METHOD' => method }
       assert_equal method, @response.body
     end
   end
@@ -4020,13 +4164,13 @@ end
 class TestNamedRouteUrlHelpers < ActionDispatch::IntegrationTest
   class CategoriesController < ActionController::Base
     def show
-      render :text => "categories#show"
+      render plain: "categories#show"
     end
   end
 
   class ProductsController < ActionController::Base
     def show
-      render :text => "products#show"
+      render plain: "products#show"
     end
   end
 
@@ -4045,11 +4189,11 @@ class TestNamedRouteUrlHelpers < ActionDispatch::IntegrationTest
   include Routes.url_helpers
 
   test "url helpers do not ignore nil parameters when using non-optimized routes" do
-    Routes.stubs(:optimize_routes_generation?).returns(false)
-
-    get "/categories/1"
-    assert_response :success
-    assert_raises(ActionController::UrlGenerationError) { product_path(nil) }
+    Routes.stub :optimize_routes_generation?, false do
+      get "/categories/1"
+      assert_response :success
+      assert_raises(ActionController::UrlGenerationError) { product_path(nil) }
+    end
   end
 end
 
@@ -4121,7 +4265,7 @@ end
 class TestInvalidUrls < ActionDispatch::IntegrationTest
   class FooController < ActionController::Base
     def show
-      render :text => "foo#show"
+      render plain: "foo#show"
     end
   end
 
@@ -4406,12 +4550,25 @@ class TestUrlGenerationErrors < ActionDispatch::IntegrationTest
     error = assert_raises(ActionController::UrlGenerationError, message){ product_path(id: nil) }
     assert_equal message, error.message
   end
+
+  test "url helpers raise message with mixed parameters when generation fails " do
+    url, missing = { action: 'show', controller: 'products', id: nil, "id"=>"url-tested"}, [:id]
+    message = "No route matches #{url.inspect} missing required keys: #{missing.inspect}"
+
+    # Optimized url helper
+    error = assert_raises(ActionController::UrlGenerationError){ product_path(nil, 'id'=>'url-tested') }
+    assert_equal message, error.message
+
+    # Non-optimized url helper
+    error = assert_raises(ActionController::UrlGenerationError, message){ product_path(id: nil, 'id'=>'url-tested') }
+    assert_equal message, error.message
+  end
 end
 
 class TestDefaultUrlOptions < ActionDispatch::IntegrationTest
   class PostsController < ActionController::Base
     def archive
-      render :text => "posts#archive"
+      render plain: "posts#archive"
     end
   end
 
diff --git a/actionpack/test/dispatch/session/abstract_store_test.rb b/actionpack/test/dispatch/session/abstract_store_test.rb
index fe1a7b4f86..d38d1bbce6 100644
--- a/actionpack/test/dispatch/session/abstract_store_test.rb
+++ b/actionpack/test/dispatch/session/abstract_store_test.rb
@@ -10,13 +10,13 @@ module ActionDispatch
           super
         end
 
-        def get_session(env, sid)
+        def find_session(env, sid)
           sid ||= 1
           session = @sessions[sid] ||= {}
           [sid, session]
         end
 
-        def set_session(env, sid, session, options)
+        def write_session(env, sid, session, options)
           @sessions[sid] = session
         end
       end
@@ -27,7 +27,7 @@ module ActionDispatch
         as.call(env)
 
         assert @env
-        assert Request::Session.find @env
+        assert Request::Session.find ActionDispatch::Request.new @env
       end
 
       def test_new_session_object_is_merged_with_old
@@ -36,11 +36,11 @@ module ActionDispatch
         as.call(env)
 
         assert @env
-        session = Request::Session.find @env
+        session = Request::Session.find ActionDispatch::Request.new @env
         session['foo'] = 'bar'
 
         as.call(@env)
-        session1 = Request::Session.find @env
+        session1 = Request::Session.find ActionDispatch::Request.new @env
 
         assert_not_equal session, session1
         assert_equal session.to_hash, session1.to_hash
diff --git a/actionpack/test/dispatch/session/cache_store_test.rb b/actionpack/test/dispatch/session/cache_store_test.rb
index 9f810cad01..dbb996973d 100644
--- a/actionpack/test/dispatch/session/cache_store_test.rb
+++ b/actionpack/test/dispatch/session/cache_store_test.rb
@@ -18,11 +18,11 @@ class CacheStoreTest < ActionDispatch::IntegrationTest
     end
 
     def get_session_value
-      render :text => "foo: #{session[:foo].inspect}"
+      render plain: "foo: #{session[:foo].inspect}"
     end
 
     def get_session_id
-      render :text => "#{request.session_options[:id]}"
+      render plain: "#{request.session.id}"
     end
 
     def call_reset_session
@@ -170,7 +170,7 @@ class CacheStoreTest < ActionDispatch::IntegrationTest
         @app = self.class.build_app(set) do |middleware|
           @cache = ActiveSupport::Cache::MemoryStore.new
           middleware.use ActionDispatch::Session::CacheStore, :key => '_session_id', :cache => @cache
-          middleware.delete "ActionDispatch::ShowExceptions"
+          middleware.delete ActionDispatch::ShowExceptions
         end
 
         yield
diff --git a/actionpack/test/dispatch/session/cookie_store_test.rb b/actionpack/test/dispatch/session/cookie_store_test.rb
index c5cd24d06e..f07e215e3a 100644
--- a/actionpack/test/dispatch/session/cookie_store_test.rb
+++ b/actionpack/test/dispatch/session/cookie_store_test.rb
@@ -16,25 +16,25 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
     end
 
     def persistent_session_id
-      render :text => session[:session_id]
+      render plain: session[:session_id]
     end
 
     def set_session_value
       session[:foo] = "bar"
-      render :text => Rack::Utils.escape(Verifier.generate(session.to_hash))
+      render plain: Rack::Utils.escape(Verifier.generate(session.to_hash))
     end
 
     def get_session_value
-      render :text => "foo: #{session[:foo].inspect}"
+      render plain: "foo: #{session[:foo].inspect}"
     end
 
     def get_session_id
-      render :text => "id: #{request.session_options[:id]}"
+      render plain: "id: #{request.session.id}"
     end
 
     def get_class_after_reset_session
       reset_session
-      render :text => "class: #{session.class}"
+      render plain: "class: #{session.class}"
     end
 
     def call_session_clear
@@ -53,7 +53,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
     end
 
     def change_session_id
-      request.session_options[:id] = nil
+      request.session.options[:id] = nil
       get_session_id
     end
 
@@ -125,7 +125,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
 
   def test_does_set_secure_cookies_over_https
     with_test_route_set(:secure => true) do
-      get '/set_session_value', nil, 'HTTPS' => 'on'
+      get '/set_session_value', headers: { 'HTTPS' => 'on' }
       assert_response :success
       assert_equal "_myapp_session=#{response.body}; path=/; secure; HttpOnly",
         headers['Set-Cookie']
@@ -274,28 +274,32 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
     with_test_route_set(:expire_after => 5.hours) do
       # First request accesses the session
       time = Time.local(2008, 4, 24)
-      Time.stubs(:now).returns(time)
-      expected_expiry = (time + 5.hours).gmtime.strftime("%a, %d %b %Y %H:%M:%S -0000")
+      cookie_body = nil
 
-      cookies[SessionKey] = SignedBar
+      Time.stub :now, time do
+        expected_expiry = (time + 5.hours).gmtime.strftime("%a, %d %b %Y %H:%M:%S -0000")
 
-      get '/set_session_value'
-      assert_response :success
+        cookies[SessionKey] = SignedBar
 
-      cookie_body = response.body
-      assert_equal "_myapp_session=#{cookie_body}; path=/; expires=#{expected_expiry}; HttpOnly",
-        headers['Set-Cookie']
+        get '/set_session_value'
+        assert_response :success
+
+        cookie_body = response.body
+        assert_equal "_myapp_session=#{cookie_body}; path=/; expires=#{expected_expiry}; HttpOnly",
+          headers['Set-Cookie']
+      end
 
       # Second request does not access the session
       time = Time.local(2008, 4, 25)
-      Time.stubs(:now).returns(time)
-      expected_expiry = (time + 5.hours).gmtime.strftime("%a, %d %b %Y %H:%M:%S -0000")
+      Time.stub :now, time do
+        expected_expiry = (time + 5.hours).gmtime.strftime("%a, %d %b %Y %H:%M:%S -0000")
 
-      get '/no_session_access'
-      assert_response :success
+        get '/no_session_access'
+        assert_response :success
 
-      assert_equal "_myapp_session=#{cookie_body}; path=/; expires=#{expected_expiry}; HttpOnly",
-        headers['Set-Cookie']
+        assert_equal "_myapp_session=#{cookie_body}; path=/; expires=#{expected_expiry}; HttpOnly",
+          headers['Set-Cookie']
+      end
     end
   end
 
@@ -331,9 +335,11 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
   private
 
     # Overwrite get to send SessionSecret in env hash
-    def get(path, parameters = nil, env = {})
-      env["action_dispatch.key_generator"] ||= Generator
-      super
+    def get(path, *args)
+      args[0] ||= {}
+      args[0][:headers] ||= {}
+      args[0][:headers]["action_dispatch.key_generator"] ||= Generator
+      super(path, *args)
     end
 
     def with_test_route_set(options = {})
@@ -346,7 +352,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
 
         @app = self.class.build_app(set) do |middleware|
           middleware.use ActionDispatch::Session::CookieStore, options
-          middleware.delete "ActionDispatch::ShowExceptions"
+          middleware.delete ActionDispatch::ShowExceptions
         end
 
         yield
diff --git a/actionpack/test/dispatch/session/mem_cache_store_test.rb b/actionpack/test/dispatch/session/mem_cache_store_test.rb
index f7a06cfed4..3fed9bad4f 100644
--- a/actionpack/test/dispatch/session/mem_cache_store_test.rb
+++ b/actionpack/test/dispatch/session/mem_cache_store_test.rb
@@ -19,11 +19,11 @@ class MemCacheStoreTest < ActionDispatch::IntegrationTest
     end
 
     def get_session_value
-      render :text => "foo: #{session[:foo].inspect}"
+      render plain: "foo: #{session[:foo].inspect}"
     end
 
     def get_session_id
-      render :text => "#{request.session_options[:id]}"
+      render plain: "#{request.session.id}"
     end
 
     def call_reset_session
@@ -172,7 +172,7 @@ class MemCacheStoreTest < ActionDispatch::IntegrationTest
 
         reset!
 
-        get '/set_session_value', :_session_id => session_id
+        get '/set_session_value', params: { _session_id: session_id }
         assert_response :success
         assert_not_equal session_id, cookies['_session_id']
       end
@@ -192,7 +192,7 @@ class MemCacheStoreTest < ActionDispatch::IntegrationTest
 
         @app = self.class.build_app(set) do |middleware|
           middleware.use ActionDispatch::Session::MemCacheStore, :key => '_session_id', :namespace => "mem_cache_store_test:#{SecureRandom.hex(10)}"
-          middleware.delete "ActionDispatch::ShowExceptions"
+          middleware.delete ActionDispatch::ShowExceptions
         end
 
         yield
diff --git a/actionpack/test/dispatch/session/test_session_test.rb b/actionpack/test/dispatch/session/test_session_test.rb
index d30461a623..3e61d123e3 100644
--- a/actionpack/test/dispatch/session/test_session_test.rb
+++ b/actionpack/test/dispatch/session/test_session_test.rb
@@ -40,4 +40,24 @@ class ActionController::TestSessionTest < ActiveSupport::TestCase
     assert_equal %w(one two), session.keys
     assert_equal %w(1 2), session.values
   end
+
+  def test_fetch_returns_default
+    session = ActionController::TestSession.new(one: '1')
+    assert_equal('2', session.fetch(:two, '2'))
+  end
+
+  def test_fetch_on_symbol_returns_value
+    session = ActionController::TestSession.new(one: '1')
+    assert_equal('1', session.fetch(:one))
+  end
+
+  def test_fetch_on_string_returns_value
+    session = ActionController::TestSession.new(one: '1')
+    assert_equal('1', session.fetch('one'))
+  end
+
+  def test_fetch_returns_block_value
+    session = ActionController::TestSession.new(one: '1')
+    assert_equal(2, session.fetch('2') { |key| key.to_i })
+  end
 end
diff --git a/actionpack/test/dispatch/show_exceptions_test.rb b/actionpack/test/dispatch/show_exceptions_test.rb
index 323fbc285e..15dd702161 100644
--- a/actionpack/test/dispatch/show_exceptions_test.rb
+++ b/actionpack/test/dispatch/show_exceptions_test.rb
@@ -11,7 +11,7 @@ class ShowExceptionsTest < ActionDispatch::IntegrationTest
       when "/bad_params"
         raise ActionDispatch::ParamsParser::ParseError.new("", StandardError.new)
       when "/method_not_allowed"
-        raise ActionController::MethodNotAllowed
+        raise ActionController::MethodNotAllowed, 'PUT'
       when "/unknown_http_method"
         raise ActionController::UnknownHttpMethod
       when "/not_found_original_exception"
@@ -27,30 +27,30 @@ class ShowExceptionsTest < ActionDispatch::IntegrationTest
   test "skip exceptions app if not showing exceptions" do
     @app = ProductionApp
     assert_raise RuntimeError do
-      get "/", {}, {'action_dispatch.show_exceptions' => false}
+      get "/", headers: { 'action_dispatch.show_exceptions' => false }
     end
   end
 
   test "rescue with error page" do
     @app = ProductionApp
 
-    get "/", {}, {'action_dispatch.show_exceptions' => true}
+    get "/", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 500
     assert_equal "500 error fixture\n", body
 
-    get "/bad_params", {}, {'action_dispatch.show_exceptions' => true}
+    get "/bad_params", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 400
     assert_equal "400 error fixture\n", body
 
-    get "/not_found", {}, {'action_dispatch.show_exceptions' => true}
+    get "/not_found", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 404
     assert_equal "404 error fixture\n", body
 
-    get "/method_not_allowed", {}, {'action_dispatch.show_exceptions' => true}
+    get "/method_not_allowed", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 405
     assert_equal "", body
 
-    get "/unknown_http_method", {}, {'action_dispatch.show_exceptions' => true}
+    get "/unknown_http_method", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 405
     assert_equal "", body
   end
@@ -61,11 +61,11 @@ class ShowExceptionsTest < ActionDispatch::IntegrationTest
     begin
       @app = ProductionApp
 
-      get "/", {}, {'action_dispatch.show_exceptions' => true}
+      get "/", headers: { 'action_dispatch.show_exceptions' => true }
       assert_response 500
       assert_equal "500 localized error fixture\n", body
 
-      get "/not_found", {}, {'action_dispatch.show_exceptions' => true}
+      get "/not_found", headers: { 'action_dispatch.show_exceptions' => true }
       assert_response 404
       assert_equal "404 error fixture\n", body
     ensure
@@ -76,14 +76,14 @@ class ShowExceptionsTest < ActionDispatch::IntegrationTest
   test "sets the HTTP charset parameter" do
     @app = ProductionApp
 
-    get "/", {}, {'action_dispatch.show_exceptions' => true}
+    get "/", headers: { 'action_dispatch.show_exceptions' => true }
     assert_equal "text/html; charset=utf-8", response.headers["Content-Type"]
   end
 
   test "show registered original exception for wrapped exceptions" do
     @app = ProductionApp
 
-    get "/not_found_original_exception", {}, {'action_dispatch.show_exceptions' => true}
+    get "/not_found_original_exception", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 404
     assert_match(/404 error/, body)
   end
@@ -93,13 +93,13 @@ class ShowExceptionsTest < ActionDispatch::IntegrationTest
       assert_kind_of AbstractController::ActionNotFound, env["action_dispatch.exception"]
       assert_equal "/404", env["PATH_INFO"]
       assert_equal "/not_found_original_exception", env["action_dispatch.original_path"]
-      [404, { "Content-Type" => "text/plain" }, ["YOU FAILED BRO"]]
+      [404, { "Content-Type" => "text/plain" }, ["YOU FAILED"]]
     end
 
     @app = ActionDispatch::ShowExceptions.new(Boomer.new, exceptions_app)
-    get "/not_found_original_exception", {}, {'action_dispatch.show_exceptions' => true}
+    get "/not_found_original_exception", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 404
-    assert_equal "YOU FAILED BRO", body
+    assert_equal "YOU FAILED", body
   end
 
   test "returns an empty response if custom exceptions app returns X-Cascade pass" do
@@ -108,7 +108,7 @@ class ShowExceptionsTest < ActionDispatch::IntegrationTest
     end
 
     @app = ActionDispatch::ShowExceptions.new(Boomer.new, exceptions_app)
-    get "/method_not_allowed", {}, {'action_dispatch.show_exceptions' => true}
+    get "/method_not_allowed", headers: { 'action_dispatch.show_exceptions' => true }
     assert_response 405
     assert_equal "", body
   end
diff --git a/actionpack/test/dispatch/ssl_test.rb b/actionpack/test/dispatch/ssl_test.rb
index c3598c5e8e..7a5b8393dc 100644
--- a/actionpack/test/dispatch/ssl_test.rb
+++ b/actionpack/test/dispatch/ssl_test.rb
@@ -1,219 +1,199 @@
 require 'abstract_unit'
 
 class SSLTest < ActionDispatch::IntegrationTest
-  def default_app
-    lambda { |env|
-      headers = {'Content-Type' => "text/html"}
-      headers['Set-Cookie'] = "id=1; path=/\ntoken=abc; path=/; secure; HttpOnly"
-      [200, headers, ["OK"]]
+  HEADERS = Rack::Utils::HeaderHash.new 'Content-Type' => 'text/html'
+
+  attr_accessor :app
+
+  def build_app(headers: {}, ssl_options: {})
+    headers = HEADERS.merge(headers)
+    ActionDispatch::SSL.new lambda { |env| [200, headers, []] }, ssl_options
+  end
+end
+
+class RedirectSSLTest < SSLTest
+  def assert_not_redirected(url, headers: {})
+    self.app = build_app
+    get url, headers: headers
+    assert_response :ok
+  end
+
+  def assert_redirected(host: nil, port: nil, status: 301, body: [],
+    deprecated_host: nil, deprecated_port: nil,
+    from: 'http://a/b?c=d', to: from.sub('http', 'https'))
+
+    self.app = build_app ssl_options: {
+      redirect: { host: host, port: port, status: status, body: body },
+      host: deprecated_host, port: deprecated_port
     }
+
+    get from
+    assert_response status
+    assert_redirected_to to
+    assert_equal body.join, @response.body
   end
 
-  def app
-    @app ||= ActionDispatch::SSL.new(default_app)
+  test 'https is not redirected' do
+    assert_not_redirected 'https://example.org'
   end
-  attr_writer :app
 
-  def test_allows_https_url
-    get "https://example.org/path?key=value"
-    assert_response :success
+  test 'proxied https is not redirected' do
+    assert_not_redirected 'http://example.org', headers: { 'HTTP_X_FORWARDED_PROTO' => 'https' }
   end
 
-  def test_allows_https_proxy_header_url
-    get "http://example.org/", {}, 'HTTP_X_FORWARDED_PROTO' => "https"
-    assert_response :success
+  test 'http is redirected to https' do
+    assert_redirected
   end
 
-  def test_redirects_http_to_https
-    get "http://example.org/path?key=value"
-    assert_response :redirect
-    assert_equal "https://example.org/path?key=value",
-      response.headers['Location']
+  test 'redirect with non-301 status' do
+    assert_redirected status: 307
   end
 
-  def test_hsts_header_by_default
-    get "https://example.org/"
-    assert_equal "max-age=31536000",
-      response.headers['Strict-Transport-Security']
+  test 'redirect with custom body' do
+    assert_redirected body: ['foo']
   end
 
-  def test_no_hsts_with_insecure_connection
-    get "http://example.org/"
-    assert_not response.headers['Strict-Transport-Security']
+  test 'redirect to specific host' do
+    assert_redirected host: 'ssl', to: 'https://ssl/b?c=d'
   end
 
-  def test_hsts_header
-    self.app = ActionDispatch::SSL.new(default_app, :hsts => true)
-    get "https://example.org/"
-    assert_equal "max-age=31536000",
-      response.headers['Strict-Transport-Security']
+  test 'redirect to default port' do
+    assert_redirected port: 443
   end
 
-  def test_disable_hsts_header
-    self.app = ActionDispatch::SSL.new(default_app, :hsts => false)
-    get "https://example.org/"
-    assert_not response.headers['Strict-Transport-Security']
+  test 'redirect to non-default port' do
+    assert_redirected port: 8443, to: 'https://a:8443/b?c=d'
   end
 
-  def test_hsts_expires
-    self.app = ActionDispatch::SSL.new(default_app, :hsts => { :expires => 500 })
-    get "https://example.org/"
-    assert_equal "max-age=500",
-      response.headers['Strict-Transport-Security']
+  test 'redirect to different host and non-default port' do
+    assert_redirected host: 'ssl', port: 8443, to: 'https://ssl:8443/b?c=d'
   end
 
-  def test_hsts_expires_with_duration
-    self.app = ActionDispatch::SSL.new(default_app, :hsts => { :expires => 1.year })
-    get "https://example.org/"
-    assert_equal "max-age=31557600",
-      response.headers['Strict-Transport-Security']
+  test 'redirect to different host including port' do
+    assert_redirected host: 'ssl:443', to: 'https://ssl:443/b?c=d'
   end
 
-  def test_hsts_include_subdomains
-    self.app = ActionDispatch::SSL.new(default_app, :hsts => { :subdomains => true })
-    get "https://example.org/"
-    assert_equal "max-age=31536000; includeSubDomains",
-      response.headers['Strict-Transport-Security']
+  test ':host is deprecated, moved within redirect: { host: … }' do
+    assert_deprecated do
+      assert_redirected deprecated_host: 'foo', to: 'https://foo/b?c=d'
+    end
   end
 
-  def test_flag_cookies_as_secure
-    get "https://example.org/"
-    assert_equal ["id=1; path=/; secure", "token=abc; path=/; secure; HttpOnly" ],
-      response.headers['Set-Cookie'].split("\n")
+  test ':port is deprecated, moved within redirect: { port: … }' do
+    assert_deprecated do
+      assert_redirected deprecated_port: 1, to: 'https://a:1/b?c=d'
+    end
   end
+end
 
-  def test_flag_cookies_as_secure_at_end_of_line
-    self.app = ActionDispatch::SSL.new(lambda { |env|
-      headers = {
-        'Content-Type' => "text/html",
-        'Set-Cookie' => "problem=def; path=/; HttpOnly; secure"
-      }
-      [200, headers, ["OK"]]
-    })
+class StrictTransportSecurityTest < SSLTest
+  EXPECTED = 'max-age=15552000'
 
-    get "https://example.org/"
-    assert_equal ["problem=def; path=/; HttpOnly; secure"],
-      response.headers['Set-Cookie'].split("\n")
+  def assert_hsts(expected, url: 'https://example.org', hsts: {}, headers: {})
+    self.app = build_app ssl_options: { hsts: hsts }, headers: headers
+    get url
+    assert_equal expected, response.headers['Strict-Transport-Security']
   end
 
-  def test_flag_cookies_as_secure_with_more_spaces_before
-    self.app = ActionDispatch::SSL.new(lambda { |env|
-      headers = {
-        'Content-Type' => "text/html",
-        'Set-Cookie' => "problem=def; path=/; HttpOnly;  secure"
-      }
-      [200, headers, ["OK"]]
-    })
+  test 'enabled by default' do
+    assert_hsts EXPECTED
+  end
 
-    get "https://example.org/"
-    assert_equal ["problem=def; path=/; HttpOnly;  secure"],
-      response.headers['Set-Cookie'].split("\n")
+  test 'not sent with http:// responses' do
+    assert_hsts nil, url: 'http://example.org'
   end
 
-  def test_flag_cookies_as_secure_with_more_spaces_after
-    self.app = ActionDispatch::SSL.new(lambda { |env|
-      headers = {
-        'Content-Type' => "text/html",
-        'Set-Cookie' => "problem=def; path=/; secure;  HttpOnly"
-      }
-      [200, headers, ["OK"]]
-    })
+  test 'defers to app-provided header' do
+    assert_hsts 'app-provided', headers: { 'Strict-Transport-Security' => 'app-provided' }
+  end
 
-    get "https://example.org/"
-    assert_equal ["problem=def; path=/; secure;  HttpOnly"],
-      response.headers['Set-Cookie'].split("\n")
+  test 'hsts: true enables default settings' do
+    assert_hsts EXPECTED, hsts: true
   end
 
+  test 'hsts: false sets max-age to zero, clearing browser HSTS settings' do
+    assert_hsts 'max-age=0', hsts: false
+  end
 
-  def test_flag_cookies_as_secure_with_has_not_spaces_before
-    self.app = ActionDispatch::SSL.new(lambda { |env|
-      headers = {
-        'Content-Type' => "text/html",
-        'Set-Cookie' => "problem=def; path=/;secure; HttpOnly"
-      }
-      [200, headers, ["OK"]]
-    })
+  test ':expires sets max-age' do
+    assert_hsts 'max-age=500', hsts: { expires: 500 }
+  end
 
-    get "https://example.org/"
-    assert_equal ["problem=def; path=/;secure; HttpOnly"],
-      response.headers['Set-Cookie'].split("\n")
+  test ':expires supports AS::Duration arguments' do
+    assert_hsts 'max-age=31557600', hsts: { expires: 1.year }
   end
 
-  def test_flag_cookies_as_secure_with_has_not_spaces_after
-    self.app = ActionDispatch::SSL.new(lambda { |env|
-      headers = {
-        'Content-Type' => "text/html",
-        'Set-Cookie' => "problem=def; path=/; secure;HttpOnly"
-      }
-      [200, headers, ["OK"]]
-    })
+  test 'include subdomains' do
+    assert_hsts "#{EXPECTED}; includeSubDomains", hsts: { subdomains: true }
+  end
 
-    get "https://example.org/"
-    assert_equal ["problem=def; path=/; secure;HttpOnly"],
-      response.headers['Set-Cookie'].split("\n")
+  test 'exclude subdomains' do
+    assert_hsts EXPECTED, hsts: { subdomains: false }
   end
 
-  def test_flag_cookies_as_secure_with_ignore_case
-    self.app = ActionDispatch::SSL.new(lambda { |env|
-      headers = {
-        'Content-Type' => "text/html",
-        'Set-Cookie' => "problem=def; path=/; Secure; HttpOnly"
-      }
-      [200, headers, ["OK"]]
-    })
+  test 'opt in to browser preload lists' do
+    assert_hsts "#{EXPECTED}; preload", hsts: { preload: true }
+  end
 
-    get "https://example.org/"
-    assert_equal ["problem=def; path=/; Secure; HttpOnly"],
-      response.headers['Set-Cookie'].split("\n")
+  test 'opt out of browser preload lists' do
+    assert_hsts EXPECTED, hsts: { preload: false }
   end
+end
 
-  def test_no_cookies
-    self.app = ActionDispatch::SSL.new(lambda { |env|
-      [200, {'Content-Type' => "text/html"}, ["OK"]]
-    })
-    get "https://example.org/"
-    assert !response.headers['Set-Cookie']
+class SecureCookiesTest < SSLTest
+  DEFAULT = %(id=1; path=/\ntoken=abc; path=/; secure; HttpOnly)
+
+  def get(**options)
+    self.app = build_app(**options)
+    super 'https://example.org'
   end
 
-  def test_redirect_to_host
-    self.app = ActionDispatch::SSL.new(default_app, :host => "ssl.example.org")
-    get "http://example.org/path?key=value"
-    assert_equal "https://ssl.example.org/path?key=value",
-      response.headers['Location']
+  def assert_cookies(*expected)
+    assert_equal expected, response.headers['Set-Cookie'].split("\n")
   end
 
-  def test_redirect_to_port
-    self.app = ActionDispatch::SSL.new(default_app, :port => 8443)
-    get "http://example.org/path?key=value"
-    assert_equal "https://example.org:8443/path?key=value",
-      response.headers['Location']
+  def test_flag_cookies_as_secure
+    get headers: { 'Set-Cookie' => DEFAULT }
+    assert_cookies 'id=1; path=/; secure', 'token=abc; path=/; secure; HttpOnly'
   end
 
-  def test_redirect_to_host_and_port
-    self.app = ActionDispatch::SSL.new(default_app, :host => "ssl.example.org", :port => 8443)
-    get "http://example.org/path?key=value"
-    assert_equal "https://ssl.example.org:8443/path?key=value",
-      response.headers['Location']
+  def test_flag_cookies_as_secure_at_end_of_line
+    get headers: { 'Set-Cookie' => 'problem=def; path=/; HttpOnly; secure' }
+    assert_cookies 'problem=def; path=/; HttpOnly; secure'
   end
 
-  def test_redirect_to_host_with_port
-    self.app = ActionDispatch::SSL.new(default_app, :host => "ssl.example.org:443")
-    get "http://example.org/path?key=value"
-    assert_equal "https://ssl.example.org:443/path?key=value",
-      response.headers['Location']
+  def test_flag_cookies_as_secure_with_more_spaces_before
+    get headers: { 'Set-Cookie' => 'problem=def; path=/; HttpOnly;  secure' }
+    assert_cookies 'problem=def; path=/; HttpOnly;  secure'
+  end
+
+  def test_flag_cookies_as_secure_with_more_spaces_after
+    get headers: { 'Set-Cookie' => 'problem=def; path=/; secure;  HttpOnly' }
+    assert_cookies 'problem=def; path=/; secure;  HttpOnly'
   end
 
-  def test_redirect_to_secure_host_when_on_subdomain
-    self.app = ActionDispatch::SSL.new(default_app, :host => "ssl.example.org")
-    get "http://ssl.example.org/path?key=value"
-    assert_equal "https://ssl.example.org/path?key=value",
-      response.headers['Location']
+  def test_flag_cookies_as_secure_with_has_not_spaces_before
+    get headers: { 'Set-Cookie' => 'problem=def; path=/;secure; HttpOnly' }
+    assert_cookies 'problem=def; path=/;secure; HttpOnly'
+  end
+
+  def test_flag_cookies_as_secure_with_has_not_spaces_after
+    get headers: { 'Set-Cookie' => 'problem=def; path=/; secure;HttpOnly' }
+    assert_cookies 'problem=def; path=/; secure;HttpOnly'
+  end
+
+  def test_flag_cookies_as_secure_with_ignore_case
+    get headers: { 'Set-Cookie' => 'problem=def; path=/; Secure; HttpOnly' }
+    assert_cookies 'problem=def; path=/; Secure; HttpOnly'
+  end
+
+  def test_no_cookies
+    get
+    assert_nil response.headers['Set-Cookie']
   end
 
-  def test_redirect_to_secure_subdomain_when_on_deep_subdomain
-    self.app = ActionDispatch::SSL.new(default_app, :host => "example.co.uk")
-    get "http://double.rainbow.what.does.it.mean.example.co.uk/path?key=value"
-    assert_equal "https://example.co.uk/path?key=value",
-      response.headers['Location']
+  def test_keeps_original_headers_behavior
+    get headers: { 'Connection' => %w[close] }
+    assert_equal 'close', response.headers['Connection']
   end
 end
diff --git a/actionpack/test/dispatch/static_test.rb b/actionpack/test/dispatch/static_test.rb
index 9a6747fb8d..1da57ab50b 100644
--- a/actionpack/test/dispatch/static_test.rb
+++ b/actionpack/test/dispatch/static_test.rb
@@ -1,8 +1,25 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'zlib'
 
 module StaticTests
+  DummyApp = lambda { |env|
+    [200, {"Content-Type" => "text/plain"}, ["Hello, World!"]]
+  }
+
+  def setup
+    silence_warnings do
+      @default_internal_encoding = Encoding.default_internal
+      @default_external_encoding = Encoding.default_external
+    end
+  end
+
+  def teardown
+    silence_warnings do
+      Encoding.default_internal = @default_internal_encoding
+      Encoding.default_external = @default_external_encoding
+    end
+  end
+
   def test_serves_dynamic_content
     assert_equal "Hello, World!", get("/nofile").body
   end
@@ -11,8 +28,24 @@ module StaticTests
     assert_equal "Hello, World!", get("/doorkeeper%E3E4").body
   end
 
+  def test_handles_urls_with_ascii_8bit
+    assert_equal "Hello, World!", get("/doorkeeper%E3E4".force_encoding('ASCII-8BIT')).body
+  end
+
+  def test_handles_urls_with_ascii_8bit_on_win_31j
+    silence_warnings do
+      Encoding.default_internal = "Windows-31J"
+      Encoding.default_external = "Windows-31J"
+    end
+    assert_equal "Hello, World!", get("/doorkeeper%E3E4".force_encoding('ASCII-8BIT')).body
+  end
+
   def test_sets_cache_control
-    response = get("/index.html")
+    app = assert_deprecated do
+      ActionDispatch::Static.new(DummyApp, @root, "public, max-age=60")
+    end
+    response = Rack::MockRequest.new(app).request("GET", "/index.html")
+
     assert_html "/index.html", response
     assert_equal "public, max-age=60", response.headers["Cache-Control"]
   end
@@ -32,6 +65,7 @@ module StaticTests
 
   def test_serves_static_index_file_in_directory
     assert_html "/foo/index.html", get("/foo/index.html")
+    assert_html "/foo/index.html", get("/foo/index")
     assert_html "/foo/index.html", get("/foo/")
     assert_html "/foo/index.html", get("/foo")
   end
@@ -41,8 +75,6 @@ module StaticTests
   end
 
   def test_served_static_file_with_non_english_filename
-    jruby_skip "Stop skipping if following bug gets fixed: " \
-      "http://jira.codehaus.org/browse/JRUBY-7192"
     assert_html "means hello in Japanese\n", get("/foo/#{Rack::Utils.escape("こんにちは.html")}")
   end
 
@@ -130,7 +162,7 @@ module StaticTests
 
   def test_does_not_modify_path_info
     file_name = "/gzip/application-a71b3024f80aea3181c09774ca17e712.js"
-    env = {'PATH_INFO' => file_name, 'HTTP_ACCEPT_ENCODING' => 'gzip'}
+    env = {'PATH_INFO' => file_name, 'HTTP_ACCEPT_ENCODING' => 'gzip', "REQUEST_METHOD" => 'POST'}
     @app.call(env)
     assert_equal file_name, env['PATH_INFO']
   end
@@ -144,6 +176,31 @@ module StaticTests
     assert_equal default_response.headers['Content-Type'], response.headers['Content-Type']
   end
 
+  def test_serves_gzip_files_with_not_modified
+    file_name = "/gzip/application-a71b3024f80aea3181c09774ca17e712.js"
+    last_modified = File.mtime(File.join(@root, "#{file_name}.gz"))
+    response = get(file_name, 'HTTP_ACCEPT_ENCODING' => 'gzip', 'HTTP_IF_MODIFIED_SINCE' => last_modified.httpdate)
+    assert_equal 304, response.status
+    assert_equal nil, response.headers['Content-Type']
+    assert_equal nil, response.headers['Content-Encoding']
+    assert_equal nil, response.headers['Vary']
+  end
+
+  def test_serves_files_with_headers
+    headers = {
+      "Access-Control-Allow-Origin" => 'http://rubyonrails.org',
+      "Cache-Control"               => 'public, max-age=60',
+      "X-Custom-Header"             => "I'm a teapot"
+    }
+
+    app      = ActionDispatch::Static.new(DummyApp, @root, headers: headers)
+    response = Rack::MockRequest.new(app).request("GET", "/foo/bar.html")
+
+    assert_equal 'http://rubyonrails.org', response.headers["Access-Control-Allow-Origin"]
+    assert_equal 'public, max-age=60',     response.headers["Cache-Control"]
+    assert_equal "I'm a teapot",           response.headers["X-Custom-Header"]
+  end
+
   # Windows doesn't allow \ / : * ? " < > | in filenames
   unless RbConfig::CONFIG['host_os'] =~ /mswin|mingw/
     def test_serves_static_file_with_colon
@@ -194,13 +251,10 @@ module StaticTests
 end
 
 class StaticTest < ActiveSupport::TestCase
-  DummyApp = lambda { |env|
-    [200, {"Content-Type" => "text/plain"}, ["Hello, World!"]]
-  }
-
   def setup
+    super
     @root = "#{FIXTURE_LOAD_PATH}/public"
-    @app = ActionDispatch::Static.new(DummyApp, @root, "public, max-age=60")
+    @app = ActionDispatch::Static.new(DummyApp, @root, headers: {'Cache-Control' => "public, max-age=60"})
   end
 
   def public_path
@@ -224,12 +278,26 @@ class StaticTest < ActiveSupport::TestCase
     }
     assert_equal(DummyApp.call(nil), @app.call(env))
   end
+
+  def test_non_default_static_index
+    @app = ActionDispatch::Static.new(DummyApp, @root, index: "other-index")
+    assert_html "/other-index.html", get("/other-index.html")
+    assert_html "/other-index.html", get("/other-index")
+    assert_html "/other-index.html", get("/")
+    assert_html "/other-index.html", get("")
+    assert_html "/foo/other-index.html", get("/foo/other-index.html")
+    assert_html "/foo/other-index.html", get("/foo/other-index")
+    assert_html "/foo/other-index.html", get("/foo/")
+    assert_html "/foo/other-index.html", get("/foo")
+  end
+
 end
 
 class StaticEncodingTest < StaticTest
   def setup
+    super
     @root = "#{FIXTURE_LOAD_PATH}/公共"
-    @app = ActionDispatch::Static.new(DummyApp, @root, "public, max-age=60")
+    @app = ActionDispatch::Static.new(DummyApp, @root, headers: {'Cache-Control' => "public, max-age=60"})
   end
 
   def public_path
diff --git a/actionpack/test/dispatch/template_assertions_test.rb b/actionpack/test/dispatch/template_assertions_test.rb
deleted file mode 100644
index 7278754b49..0000000000
--- a/actionpack/test/dispatch/template_assertions_test.rb
+++ /dev/null
@@ -1,110 +0,0 @@
-require 'abstract_unit'
-
-class AssertTemplateController < ActionController::Base
-  def render_with_partial
-    render partial: 'test/partial'
-  end
-
-  def render_with_template
-    render 'test/hello_world'
-  end
-
-  def render_with_layout
-    @variable_for_layout = 'hello'
-    render 'test/hello_world', layout: "layouts/standard"
-  end
-
-  def render_with_file
-    render file: 'README.rdoc'
-  end
-
-  def render_nothing
-    head :ok
-  end
-end
-
-class AssertTemplateControllerTest < ActionDispatch::IntegrationTest
-  def test_template_reset_between_requests
-    get '/assert_template/render_with_template'
-    assert_template 'test/hello_world'
-
-    get '/assert_template/render_nothing'
-    assert_template nil
-  end
-
-  def test_partial_reset_between_requests
-    get '/assert_template/render_with_partial'
-    assert_template partial: 'test/_partial'
-
-    get '/assert_template/render_nothing'
-    assert_template partial: nil
-  end
-
-  def test_layout_reset_between_requests
-    get '/assert_template/render_with_layout'
-    assert_template layout: 'layouts/standard'
-
-    get '/assert_template/render_nothing'
-    assert_template layout: nil
-  end
-
-  def test_file_reset_between_requests
-    get '/assert_template/render_with_file'
-    assert_template file: 'README.rdoc'
-
-    get '/assert_template/render_nothing'
-    assert_template file: nil
-  end
-
-  def test_template_reset_between_requests_when_opening_a_session
-    open_session do |session|
-      session.get '/assert_template/render_with_template'
-      session.assert_template 'test/hello_world'
-
-      session.get '/assert_template/render_nothing'
-      session.assert_template nil
-    end
-  end
-
-  def test_partial_reset_between_requests_when_opening_a_session
-    open_session do |session|
-      session.get '/assert_template/render_with_partial'
-      session.assert_template partial: 'test/_partial'
-
-      session.get '/assert_template/render_nothing'
-      session.assert_template partial: nil
-    end
-  end
-
-  def test_layout_reset_between_requests_when_opening_a_session
-    open_session do |session|
-      session.get '/assert_template/render_with_layout'
-      session.assert_template layout: 'layouts/standard'
-
-      session.get '/assert_template/render_nothing'
-      session.assert_template layout: nil
-    end
-  end
-
-  def test_file_reset_between_requests_when_opening_a_session
-    open_session do |session|
-      session.get '/assert_template/render_with_file'
-      session.assert_template file: 'README.rdoc'
-
-      session.get '/assert_template/render_nothing'
-      session.assert_template file: nil
-    end
-  end
-
-  def test_assigns_do_not_reset_template_assertion
-    get '/assert_template/render_with_layout'
-    assert_equal 'hello', assigns(:variable_for_layout)
-    assert_template layout: 'layouts/standard'
-  end
-
-  def test_cookies_do_not_reset_template_assertion
-    get '/assert_template/render_with_layout'
-    cookies
-    assert_template layout: 'layouts/standard'
-  end
-end
diff --git a/actionpack/test/dispatch/test_request_test.rb b/actionpack/test/dispatch/test_request_test.rb
index cc35d4594e..51c469a61a 100644
--- a/actionpack/test/dispatch/test_request_test.rb
+++ b/actionpack/test/dispatch/test_request_test.rb
@@ -2,7 +2,7 @@ require 'abstract_unit'
 
 class TestRequestTest < ActiveSupport::TestCase
   test "sane defaults" do
-    env = ActionDispatch::TestRequest.new.env
+    env = ActionDispatch::TestRequest.create.env
 
     assert_equal "GET", env.delete("REQUEST_METHOD")
     assert_equal "off", env.delete("HTTPS")
@@ -24,12 +24,10 @@ class TestRequestTest < ActiveSupport::TestCase
     assert_equal true, env.delete("rack.multithread")
     assert_equal true, env.delete("rack.multiprocess")
     assert_equal false, env.delete("rack.run_once")
-
-    assert env.empty?, env.inspect
   end
 
   test "cookie jar" do
-    req = ActionDispatch::TestRequest.new
+    req = ActionDispatch::TestRequest.create({})
 
     assert_equal({}, req.cookies)
     assert_equal nil, req.env["HTTP_COOKIE"]
@@ -55,40 +53,38 @@ class TestRequestTest < ActiveSupport::TestCase
     assert_cookies({"user_name" => "david"}, req.cookie_jar)
   end
 
-  test "does not complain when Rails.application is nil" do
-    Rails.stubs(:application).returns(nil)
-    req = ActionDispatch::TestRequest.new
-
+  test "does not complain when there is no application config" do
+    req = ActionDispatch::TestRequest.create({})
     assert_equal false, req.env.empty?
   end
 
   test "default remote address is 0.0.0.0" do
-    req = ActionDispatch::TestRequest.new
+    req = ActionDispatch::TestRequest.create({})
     assert_equal '0.0.0.0', req.remote_addr
   end
 
   test "allows remote address to be overridden" do
-    req = ActionDispatch::TestRequest.new('REMOTE_ADDR' => '127.0.0.1')
+    req = ActionDispatch::TestRequest.create('REMOTE_ADDR' => '127.0.0.1')
     assert_equal '127.0.0.1', req.remote_addr
   end
 
   test "default host is test.host" do
-    req = ActionDispatch::TestRequest.new
+    req = ActionDispatch::TestRequest.create({})
     assert_equal 'test.host', req.host
   end
 
   test "allows host to be overridden" do
-    req = ActionDispatch::TestRequest.new('HTTP_HOST' => 'www.example.com')
+    req = ActionDispatch::TestRequest.create('HTTP_HOST' => 'www.example.com')
     assert_equal 'www.example.com', req.host
   end
 
   test "default user agent is 'Rails Testing'" do
-    req = ActionDispatch::TestRequest.new
+    req = ActionDispatch::TestRequest.create({})
     assert_equal 'Rails Testing', req.user_agent
   end
 
   test "allows user agent to be overridden" do
-    req = ActionDispatch::TestRequest.new('HTTP_USER_AGENT' => 'GoogleBot')
+    req = ActionDispatch::TestRequest.create('HTTP_USER_AGENT' => 'GoogleBot')
     assert_equal 'GoogleBot', req.user_agent
   end
 
diff --git a/actionpack/test/dispatch/test_response_test.rb b/actionpack/test/dispatch/test_response_test.rb
index dc17668def..a4f9d56a6a 100644
--- a/actionpack/test/dispatch/test_response_test.rb
+++ b/actionpack/test/dispatch/test_response_test.rb
@@ -11,10 +11,9 @@ class TestResponseTest < ActiveSupport::TestCase
   end
 
   test "helpers" do
-    assert_response_code_range 200..299, :success?
-    assert_response_code_range [404],    :missing?
-    assert_response_code_range 300..399, :redirect?
-    assert_response_code_range 500..599, :error?
+    assert_response_code_range 200..299, :successful?
+    assert_response_code_range [404],    :not_found?
+    assert_response_code_range 300..399, :redirection?
     assert_response_code_range 500..599, :server_error?
     assert_response_code_range 400..499, :client_error?
   end
diff --git a/actionpack/test/dispatch/url_generation_test.rb b/actionpack/test/dispatch/url_generation_test.rb
index 8f79e7bf9a..fd4ede4d1b 100644
--- a/actionpack/test/dispatch/url_generation_test.rb
+++ b/actionpack/test/dispatch/url_generation_test.rb
@@ -8,7 +8,7 @@ module TestUrlGeneration
     class ::MyRouteGeneratingController < ActionController::Base
       include Routes.url_helpers
       def index
-        render :text => foo_path
+        render plain: foo_path
       end
     end
 
@@ -39,12 +39,12 @@ module TestUrlGeneration
     end
 
     test "the request's SCRIPT_NAME takes precedence over the route" do
-      get "/foo", {}, 'SCRIPT_NAME' => "/new", 'action_dispatch.routes' => Routes
+      get "/foo", headers: { 'SCRIPT_NAME' => "/new", 'action_dispatch.routes' => Routes }
       assert_equal "/new/foo", response.body
     end
 
     test "the request's SCRIPT_NAME wraps the mounted app's" do
-      get '/new/bar/foo', {}, 'SCRIPT_NAME' => '/new', 'PATH_INFO' => '/bar/foo', 'action_dispatch.routes' => Routes
+      get '/new/bar/foo', headers: { 'SCRIPT_NAME' => '/new', 'PATH_INFO' => '/bar/foo', 'action_dispatch.routes' => Routes }
       assert_equal "/new/bar/foo", response.body
     end
 
diff --git a/actionpack/test/fixtures/collection_cache/index.html.erb b/actionpack/test/fixtures/collection_cache/index.html.erb
new file mode 100644
index 0000000000..521b1450df
--- /dev/null
+++ b/actionpack/test/fixtures/collection_cache/index.html.erb
@@ -0,0 +1 @@
+<%= render @customers %>
\ No newline at end of file
diff --git a/actionpack/test/fixtures/customers/_commented_customer.html.erb b/actionpack/test/fixtures/customers/_commented_customer.html.erb
new file mode 100644
index 0000000000..8cc9c1ec13
--- /dev/null
+++ b/actionpack/test/fixtures/customers/_commented_customer.html.erb
@@ -0,0 +1,5 @@
+<%# I'm a comment %>
+<% cache customer do %>
+  <% controller.partial_rendered_times += 1 %>
+  <%= customer.name %>, <%= customer.id %>
+<% end %>
\ No newline at end of file
diff --git a/actionpack/test/fixtures/customers/_customer.html.erb b/actionpack/test/fixtures/customers/_customer.html.erb
new file mode 100644
index 0000000000..5105090d4b
--- /dev/null
+++ b/actionpack/test/fixtures/customers/_customer.html.erb
@@ -0,0 +1,4 @@
+<% cache customer do %>
+  <% controller.partial_rendered_times += 1 %>
+  <%= customer.name %>, <%= customer.id %>
+<% end %>
\ No newline at end of file
diff --git a/actionpack/test/fixtures/layouts/standard.html.erb b/actionpack/test/fixtures/layouts/standard.html.erb
index 5e6c24fe39..48882dca35 100644
--- a/actionpack/test/fixtures/layouts/standard.html.erb
+++ b/actionpack/test/fixtures/layouts/standard.html.erb
@@ -1 +1 @@
-<html><%= yield %><%= @variable_for_layout %></html>
\ No newline at end of file
+<html><%= yield %><%= @variable_for_layout %></html>
diff --git a/actionpack/test/fixtures/multipart/utf8_filename b/actionpack/test/fixtures/multipart/utf8_filename
new file mode 100644
index 0000000000..60738d53b0
--- /dev/null
+++ b/actionpack/test/fixtures/multipart/utf8_filename
@@ -0,0 +1,10 @@
+--AaB03x

+Content-Disposition: form-data; name="foo"

+

+bar

+--AaB03x

+Content-Disposition: form-data; name="file"; filename="ファイル%名.txt"

+Content-Type: text/plain

+

+contents

+--AaB03x--

diff --git a/actionpack/test/fixtures/public/foo/other-index.html b/actionpack/test/fixtures/public/foo/other-index.html
new file mode 100644
index 0000000000..51c90c26ea
--- /dev/null
+++ b/actionpack/test/fixtures/public/foo/other-index.html
@@ -0,0 +1 @@
+/foo/other-index.html
\ No newline at end of file
diff --git a/actionpack/test/fixtures/public/other-index.html b/actionpack/test/fixtures/public/other-index.html
new file mode 100644
index 0000000000..0820dfcb6e
--- /dev/null
+++ b/actionpack/test/fixtures/public/other-index.html
@@ -0,0 +1 @@
+/other-index.html
\ No newline at end of file
diff --git a/actionpack/test/fixtures/symlink_parent/symlinked_layout.erb b/actionpack/test/fixtures/symlink_parent/symlinked_layout.erb
deleted file mode 100644
index bda57d0fae..0000000000
--- a/actionpack/test/fixtures/symlink_parent/symlinked_layout.erb
+++ /dev/null
@@ -1,5 +0,0 @@
-This is my layout
-
-<%= yield %>
-
-End.
diff --git a/actionpack/test/fixtures/公共/foo/other-index.html b/actionpack/test/fixtures/公共/foo/other-index.html
new file mode 100644
index 0000000000..51c90c26ea
--- /dev/null
+++ b/actionpack/test/fixtures/公共/foo/other-index.html
@@ -0,0 +1 @@
+/foo/other-index.html
\ No newline at end of file
diff --git a/actionpack/test/fixtures/公共/other-index.html b/actionpack/test/fixtures/公共/other-index.html
new file mode 100644
index 0000000000..0820dfcb6e
--- /dev/null
+++ b/actionpack/test/fixtures/公共/other-index.html
@@ -0,0 +1 @@
+/other-index.html
\ No newline at end of file
diff --git a/actionpack/test/journey/nodes/symbol_test.rb b/actionpack/test/journey/nodes/symbol_test.rb
index d411a5018a..adf85b860c 100644
--- a/actionpack/test/journey/nodes/symbol_test.rb
+++ b/actionpack/test/journey/nodes/symbol_test.rb
@@ -5,7 +5,7 @@ module ActionDispatch
     module Nodes
       class TestSymbol < ActiveSupport::TestCase
         def test_default_regexp?
-          sym = Symbol.new nil
+          sym = Symbol.new "foo"
           assert sym.default_regexp?
 
           sym.regexp = nil
diff --git a/actionpack/test/journey/path/pattern_test.rb b/actionpack/test/journey/path/pattern_test.rb
index 6939b426f6..72858f5eda 100644
--- a/actionpack/test/journey/path/pattern_test.rb
+++ b/actionpack/test/journey/path/pattern_test.rb
@@ -4,6 +4,8 @@ module ActionDispatch
   module Journey
     module Path
       class TestPattern < ActiveSupport::TestCase
+        SEPARATORS = ["/", ".", "?"].join
+
         x = /.+/
         {
           '/:controller(/:action)'       => %r{\A/(#{x})(?:/([^/.?]+))?\Z},
@@ -19,12 +21,12 @@ module ActionDispatch
           '/:foo|*bar'                   => %r{\A/(?:([^/.?]+)|(.+))\Z},
         }.each do |path, expected|
           define_method(:"test_to_regexp_#{path}") do
-            strexp = Router::Strexp.build(
+            path = Pattern.build(
               path,
               { :controller => /.+/ },
-              ["/", ".", "?"]
+              SEPARATORS,
+              true
             )
-            path = Pattern.new strexp
             assert_equal(expected, path.to_regexp)
           end
         end
@@ -43,13 +45,12 @@ module ActionDispatch
           '/:foo|*bar'                   => %r{\A/(?:([^/.?]+)|(.+))},
         }.each do |path, expected|
           define_method(:"test_to_non_anchored_regexp_#{path}") do
-            strexp = Router::Strexp.build(
+            path = Pattern.build(
               path,
               { :controller => /.+/ },
-              ["/", ".", "?"],
+              SEPARATORS,
               false
             )
-            path = Pattern.new strexp
             assert_equal(expected, path.to_regexp)
           end
         end
@@ -67,27 +68,27 @@ module ActionDispatch
           '/:controller/*foo/bar'        => %w{ controller foo },
         }.each do |path, expected|
           define_method(:"test_names_#{path}") do
-            strexp = Router::Strexp.build(
+            path = Pattern.build(
               path,
               { :controller => /.+/ },
-              ["/", ".", "?"]
+              SEPARATORS,
+              true
             )
-            path = Pattern.new strexp
             assert_equal(expected, path.names)
           end
         end
 
         def test_to_regexp_with_extended_group
-          strexp = Router::Strexp.build(
+          path = Pattern.build(
             '/page/:name',
             { :name => /
               #ROFL
               (tender|love
               #MAO
               )/x },
-            ["/", ".", "?"]
+            SEPARATORS,
+            true
           )
-          path = Pattern.new strexp
           assert_match(path, '/page/tender')
           assert_match(path, '/page/love')
           assert_no_match(path, '/page/loving')
@@ -105,23 +106,23 @@ module ActionDispatch
         end
 
         def test_to_regexp_match_non_optional
-          strexp = Router::Strexp.build(
+          path = Pattern.build(
             '/:name',
             { :name => /\d+/ },
-            ["/", ".", "?"]
+            SEPARATORS,
+            true
           )
-          path = Pattern.new strexp
           assert_match(path, '/123')
           assert_no_match(path, '/')
         end
 
         def test_to_regexp_with_group
-          strexp = Router::Strexp.build(
+          path = Pattern.build(
             '/page/:name',
             { :name => /(tender|love)/ },
-            ["/", ".", "?"]
+            SEPARATORS,
+            true
           )
-          path = Pattern.new strexp
           assert_match(path, '/page/tender')
           assert_match(path, '/page/love')
           assert_no_match(path, '/page/loving')
@@ -129,15 +130,13 @@ module ActionDispatch
 
         def test_ast_sets_regular_expressions
           requirements = { :name => /(tender|love)/, :value => /./ }
-          strexp = Router::Strexp.build(
+          path = Pattern.build(
             '/page/:name/:value',
             requirements,
-            ["/", ".", "?"]
+            SEPARATORS,
+            true
           )
 
-          assert_equal requirements, strexp.requirements
-
-          path = Pattern.new strexp
           nodes = path.ast.grep(Nodes::Symbol)
           assert_equal 2, nodes.length
           nodes.each do |node|
@@ -146,24 +145,24 @@ module ActionDispatch
         end
 
         def test_match_data_with_group
-          strexp = Router::Strexp.build(
+          path = Pattern.build(
             '/page/:name',
             { :name => /(tender|love)/ },
-            ["/", ".", "?"]
+            SEPARATORS,
+            true
           )
-          path = Pattern.new strexp
           match = path.match '/page/tender'
           assert_equal 'tender', match[1]
           assert_equal 2, match.length
         end
 
         def test_match_data_with_multi_group
-          strexp = Router::Strexp.build(
+          path = Pattern.build(
             '/page/:name/:id',
             { :name => /t(((ender|love)))()/ },
-            ["/", ".", "?"]
+            SEPARATORS,
+            true
           )
-          path = Pattern.new strexp
           match = path.match '/page/tender/10'
           assert_equal 'tender', match[1]
           assert_equal '10', match[2]
@@ -173,30 +172,29 @@ module ActionDispatch
 
         def test_star_with_custom_re
           z = /\d+/
-          strexp = Router::Strexp.build(
+          path = Pattern.build(
             '/page/*foo',
             { :foo => z },
-            ["/", ".", "?"]
+            SEPARATORS,
+            true
           )
-          path = Pattern.new strexp
           assert_equal(%r{\A/page/(#{z})\Z}, path.to_regexp)
         end
 
         def test_insensitive_regexp_with_group
-          strexp = Router::Strexp.build(
+          path = Pattern.build(
             '/page/:name/aaron',
             { :name => /(tender|love)/i },
-            ["/", ".", "?"]
+            SEPARATORS,
+            true
           )
-          path = Pattern.new strexp
           assert_match(path, '/page/TENDER/aaron')
           assert_match(path, '/page/loVE/aaron')
           assert_no_match(path, '/page/loVE/AAron')
         end
 
         def test_to_regexp_with_strexp
-          strexp = Router::Strexp.build('/:controller', { }, ["/", ".", "?"])
-          path = Pattern.new strexp
+          path = Pattern.build('/:controller', { }, SEPARATORS, true)
           x = %r{\A/([^/.?]+)\Z}
 
           assert_equal(x.source, path.source)
diff --git a/actionpack/test/journey/route_test.rb b/actionpack/test/journey/route_test.rb
index 21d867aca0..22c3b8113d 100644
--- a/actionpack/test/journey/route_test.rb
+++ b/actionpack/test/journey/route_test.rb
@@ -7,7 +7,7 @@ module ActionDispatch
         app      = Object.new
         path     = Path::Pattern.from_string '/:controller(/:action(/:id(.:format)))'
         defaults = {}
-        route    = Route.new("name", app, path, {}, defaults)
+        route    = Route.build("name", app, path, {}, [], defaults)
 
         assert_equal app, route.app
         assert_equal path, route.path
@@ -18,30 +18,37 @@ module ActionDispatch
         app      = Object.new
         path     = Path::Pattern.from_string '/:controller(/:action(/:id(.:format)))'
         defaults = {}
-        route    = Route.new("name", app, path, {}, defaults)
+        route    = Route.build("name", app, path, {}, [], defaults)
 
         route.ast.grep(Nodes::Terminal).each do |node|
           assert_equal route, node.memo
         end
       end
 
+      def test_path_requirements_override_defaults
+        path    = Path::Pattern.build(':name', { name: /love/ }, '/', true)
+        defaults  = { name: 'tender' }
+        route     = Route.build('name', nil, path, {}, [], defaults)
+        assert_equal(/love/, route.requirements[:name])
+      end
+
       def test_ip_address
         path  = Path::Pattern.from_string '/messages/:id(.:format)'
-        route = Route.new("name", nil, path, {:ip => '192.168.1.1'},
+        route = Route.build("name", nil, path, {:ip => '192.168.1.1'}, [],
                           { :controller => 'foo', :action => 'bar' })
         assert_equal '192.168.1.1', route.ip
       end
 
       def test_default_ip
         path  = Path::Pattern.from_string '/messages/:id(.:format)'
-        route = Route.new("name", nil, path, {},
+        route = Route.build("name", nil, path, {}, [],
                           { :controller => 'foo', :action => 'bar' })
         assert_equal(//, route.ip)
       end
 
       def test_format_with_star
         path  = Path::Pattern.from_string '/:controller/*extra'
-        route = Route.new("name", nil, path, {},
+        route = Route.build("name", nil, path, {}, [],
                           { :controller => 'foo', :action => 'bar' })
         assert_equal '/foo/himom', route.format({
           :controller => 'foo',
@@ -51,7 +58,7 @@ module ActionDispatch
 
       def test_connects_all_match
         path  = Path::Pattern.from_string '/:controller(/:action(/:id(.:format)))'
-        route = Route.new("name", nil, path, {:action => 'bar'}, { :controller => 'foo' })
+        route = Route.build("name", nil, path, {:action => 'bar'}, [], { :controller => 'foo' })
 
         assert_equal '/foo/bar/10', route.format({
           :controller => 'foo',
@@ -62,34 +69,34 @@ module ActionDispatch
 
       def test_extras_are_not_included_if_optional
         path  = Path::Pattern.from_string '/page/:id(/:action)'
-        route = Route.new("name", nil, path, { }, { :action => 'show' })
+        route = Route.build("name", nil, path, { }, [], { :action => 'show' })
 
         assert_equal '/page/10', route.format({ :id => 10 })
       end
 
       def test_extras_are_not_included_if_optional_with_parameter
         path  = Path::Pattern.from_string '(/sections/:section)/pages/:id'
-        route = Route.new("name", nil, path, { }, { :action => 'show' })
+        route = Route.build("name", nil, path, { }, [], { :action => 'show' })
 
         assert_equal '/pages/10', route.format({:id => 10})
       end
 
       def test_extras_are_not_included_if_optional_parameter_is_nil
         path  = Path::Pattern.from_string '(/sections/:section)/pages/:id'
-        route = Route.new("name", nil, path, { }, { :action => 'show' })
+        route = Route.build("name", nil, path, { }, [], { :action => 'show' })
 
         assert_equal '/pages/10', route.format({:id => 10, :section => nil})
       end
 
       def test_score
-        constraints = {:required_defaults => [:controller, :action]}
+        constraints = {}
         defaults = {:controller=>"pages", :action=>"show"}
 
         path = Path::Pattern.from_string "/page/:id(/:action)(.:format)"
-        specific = Route.new "name", nil, path, constraints, defaults
+        specific = Route.build "name", nil, path, constraints, [:controller, :action], defaults
 
         path = Path::Pattern.from_string "/:controller(/:action(/:id))(.:format)"
-        generic = Route.new "name", nil, path, constraints
+        generic = Route.build "name", nil, path, constraints, [], {}
 
         knowledge = {:id=>20, :controller=>"pages", :action=>"show"}
 
diff --git a/actionpack/test/journey/router/utils_test.rb b/actionpack/test/journey/router/utils_test.rb
index 9b2b85ec73..2b505f081e 100644
--- a/actionpack/test/journey/router/utils_test.rb
+++ b/actionpack/test/journey/router/utils_test.rb
@@ -1,4 +1,3 @@
-# coding: utf-8
 require 'abstract_unit'
 
 module ActionDispatch
diff --git a/actionpack/test/journey/router_test.rb b/actionpack/test/journey/router_test.rb
index 19c61b5914..15d51e5d6c 100644
--- a/actionpack/test/journey/router_test.rb
+++ b/actionpack/test/journey/router_test.rb
@@ -1,141 +1,45 @@
-# encoding: UTF-8
 require 'abstract_unit'
 
 module ActionDispatch
   module Journey
     class TestRouter < ActiveSupport::TestCase
-      attr_reader :routes
+      attr_reader :routes, :mapper
 
       def setup
         @app       = Routing::RouteSet::Dispatcher.new({})
-        @routes    = Routes.new
-        @router    = Router.new(@routes)
-        @formatter = Formatter.new(@routes)
-      end
-
-      class FakeRequestFeeler < Struct.new(:env, :called)
-        def new env
-          self.env = env
-          self
-        end
-
-        def hello
-          self.called = true
-          'world'
-        end
-
-        def path_info; env['PATH_INFO']; end
-        def request_method; env['REQUEST_METHOD']; end
-        def ip; env['REMOTE_ADDR']; end
+        @route_set  = ActionDispatch::Routing::RouteSet.new
+        @routes = @route_set.router.routes
+        @router = @route_set.router
+        @formatter = @route_set.formatter
+        @mapper = ActionDispatch::Routing::Mapper.new @route_set
       end
 
       def test_dashes
-        router = Router.new(routes)
-
-        exp = Router::Strexp.build '/foo-bar-baz', {}, ['/.?']
-        path  = Path::Pattern.new exp
-
-        routes.add_route nil, path, {}, {:id => nil}, {}
+        mapper.get '/foo-bar-baz', to: 'foo#bar'
 
         env = rails_env 'PATH_INFO' => '/foo-bar-baz'
         called = false
-        router.recognize(env) do |r, params|
+        @router.recognize(env) do |r, params|
           called = true
         end
         assert called
       end
 
       def test_unicode
-        router = Router.new(routes)
+        mapper.get '/ほげ', to: 'foo#bar'
 
         #match the escaped version of /ほげ
-        exp = Router::Strexp.build '/%E3%81%BB%E3%81%92', {}, ['/.?']
-        path  = Path::Pattern.new exp
-
-        routes.add_route nil, path, {}, {:id => nil}, {}
-
         env = rails_env 'PATH_INFO' => '/%E3%81%BB%E3%81%92'
         called = false
-        router.recognize(env) do |r, params|
+        @router.recognize(env) do |r, params|
           called = true
         end
         assert called
       end
 
-      def test_request_class_and_requirements_success
-        klass  = FakeRequestFeeler.new nil
-        router = Router.new(routes)
-
-        requirements = { :hello => /world/ }
-
-        exp = Router::Strexp.build '/foo(/:id)', {}, ['/.?']
-        path  = Path::Pattern.new exp
-
-        routes.add_route nil, path, requirements, {:id => nil}, {}
-
-        env = rails_env({'PATH_INFO' => '/foo/10'}, klass)
-        router.recognize(env) do |r, params|
-          assert_equal({:id => '10'}, params)
-        end
-
-        assert klass.called, 'hello should have been called'
-        assert_equal env.env, klass.env
-      end
-
-      def test_request_class_and_requirements_fail
-        klass  = FakeRequestFeeler.new nil
-        router = Router.new(routes)
-
-        requirements = { :hello => /mom/ }
-
-        exp = Router::Strexp.build '/foo(/:id)', {}, ['/.?']
-        path  = Path::Pattern.new exp
-
-        router.routes.add_route nil, path, requirements, {:id => nil}, {}
-
-        env = rails_env({'PATH_INFO' => '/foo/10'}, klass)
-        router.recognize(env) do |r, params|
-          flunk 'route should not be found'
-        end
-
-        assert klass.called, 'hello should have been called'
-        assert_equal env.env, klass.env
-      end
-
-      class CustomPathRequest < ActionDispatch::Request
-        def path_info
-          env['custom.path_info']
-        end
-
-        def path_info=(x)
-          env['custom.path_info'] = x
-        end
-      end
-
-      def test_request_class_overrides_path_info
-        router = Router.new(routes)
-
-        exp = Router::Strexp.build '/bar', {}, ['/.?']
-        path = Path::Pattern.new exp
-
-        routes.add_route nil, path, {}, {}, {}
-
-        env = rails_env({'PATH_INFO' => '/foo',
-                         'custom.path_info' => '/bar'}, CustomPathRequest)
-
-        recognized = false
-        router.recognize(env) do |r, params|
-          recognized = true
-        end
-
-        assert recognized, "route should have been recognized"
-      end
-
       def test_regexp_first_precedence
-        add_routes @router, [
-          Router::Strexp.build("/whois/:domain", {:domain => /\w+\.[\w\.]+/}, ['/', '.', '?']),
-          Router::Strexp.build("/whois/:id(.:format)", {}, ['/', '.', '?'])
-        ]
+        mapper.get "/whois/:domain", :domain => /\w+\.[\w\.]+/, to: "foo#bar"
+        mapper.get "/whois/:id(.:format)", to: "foo#baz"
 
         env = rails_env 'PATH_INFO' => '/whois/example.com'
 
@@ -147,25 +51,21 @@ module ActionDispatch
 
         r = list.first
 
-        assert_equal '/whois/:domain', r.path.spec.to_s
+        assert_equal '/whois/:domain(.:format)', r.path.spec.to_s
       end
 
       def test_required_parts_verified_are_anchored
-        add_routes @router, [
-          Router::Strexp.build("/foo/:id", { :id => /\d/ }, ['/', '.', '?'], false)
-        ]
+        mapper.get "/foo/:id", :id => /\d/, anchor: false, to: "foo#bar"
 
         assert_raises(ActionController::UrlGenerationError) do
-          @formatter.generate(nil, { :id => '10' }, { })
+          @formatter.generate(nil, { :controller => "foo", :action => "bar", :id => '10' }, { })
         end
       end
 
       def test_required_parts_are_verified_when_building
-        add_routes @router, [
-          Router::Strexp.build("/foo/:id", { :id => /\d+/ }, ['/', '.', '?'], false)
-        ]
+        mapper.get "/foo/:id", :id => /\d+/, anchor: false, to: "foo#bar"
 
-        path, _ = @formatter.generate(nil, { :id => '10' }, { })
+        path, _ = @formatter.generate(nil, { :controller => "foo", :action => "bar", :id => '10' }, { })
         assert_equal '/foo/10', path
 
         assert_raises(ActionController::UrlGenerationError) do
@@ -174,25 +74,22 @@ module ActionDispatch
       end
 
       def test_only_required_parts_are_verified
-        add_routes @router, [
-          Router::Strexp.build("/foo(/:id)", {:id => /\d/}, ['/', '.', '?'], false)
-        ]
+        mapper.get "/foo(/:id)", :id => /\d/, :to => "foo#bar"
 
-        path, _ = @formatter.generate(nil, { :id => '10' }, { })
+        path, _ = @formatter.generate(nil, { :controller => "foo", :action => "bar", :id => '10' }, { })
         assert_equal '/foo/10', path
 
-        path, _ = @formatter.generate(nil, { }, { })
+        path, _ = @formatter.generate(nil, { :controller => "foo", :action => "bar" }, { })
         assert_equal '/foo', path
 
-        path, _ = @formatter.generate(nil, { :id => 'aa' }, { })
+        path, _ = @formatter.generate(nil, { :controller => "foo", :action => "bar", :id => 'aa' }, { })
         assert_equal '/foo/aa', path
       end
 
       def test_knows_what_parts_are_missing_from_named_route
         route_name = "gorby_thunderhorse"
-        pattern = Router::Strexp.build("/foo/:id", { :id => /\d+/ }, ['/', '.', '?'], false)
-        path = Path::Pattern.new pattern
-        @router.routes.add_route nil, path, {}, {}, route_name
+        mapper = ActionDispatch::Routing::Mapper.new @route_set
+        mapper.get "/foo/:id", :as => route_name, :id => /\d+/, :to => "foo#bar"
 
         error = assert_raises(ActionController::UrlGenerationError) do
           @formatter.generate(route_name, { }, { })
@@ -212,7 +109,7 @@ module ActionDispatch
       end
 
       def test_X_Cascade
-        add_routes @router, [ "/messages(.:format)" ]
+        mapper.get "/messages(.:format)", to: "foo#bar"
         resp = @router.serve(rails_env({ 'REQUEST_METHOD' => 'GET', 'PATH_INFO' => '/lol' }))
         assert_equal ['Not Found'], resp.last
         assert_equal 'pass', resp[1]['X-Cascade']
@@ -233,24 +130,21 @@ module ActionDispatch
       end
 
       def test_defaults_merge_correctly
-        path  = Path::Pattern.from_string '/foo(/:id)'
-        @router.routes.add_route nil, path, {}, {:id => nil}, {}
+        mapper.get '/foo(/:id)', to: "foo#bar", id: nil
 
         env = rails_env 'PATH_INFO' => '/foo/10'
         @router.recognize(env) do |r, params|
-          assert_equal({:id => '10'}, params)
+          assert_equal({:id => '10', :controller => "foo", :action => "bar"}, params)
         end
 
         env = rails_env 'PATH_INFO' => '/foo'
         @router.recognize(env) do |r, params|
-          assert_equal({:id => nil}, params)
+          assert_equal({:id => nil, :controller => "foo", :action => "bar"}, params)
         end
       end
 
       def test_recognize_with_unbound_regexp
-        add_routes @router, [
-          Router::Strexp.build("/foo", { }, ['/', '.', '?'], false)
-        ]
+        mapper.get "/foo", anchor: false, to: "foo#bar"
 
         env = rails_env 'PATH_INFO' => '/foo/bar'
 
@@ -261,9 +155,7 @@ module ActionDispatch
       end
 
       def test_bound_regexp_keeps_path_info
-        add_routes @router, [
-          Router::Strexp.build("/foo", { }, ['/', '.', '?'], true)
-        ]
+        mapper.get "/foo", to: "foo#bar"
 
         env = rails_env 'PATH_INFO' => '/foo'
 
@@ -276,12 +168,14 @@ module ActionDispatch
       end
 
       def test_path_not_found
-        add_routes @router, [
+        [
           "/messages(.:format)",
           "/messages/new(.:format)",
           "/messages/:id/edit(.:format)",
           "/messages/:id(.:format)"
-        ]
+        ].each do |path|
+          mapper.get path, to: "foo#bar"
+        end
         env = rails_env 'PATH_INFO' => '/messages/unknown/path'
         yielded = false
 
@@ -292,32 +186,29 @@ module ActionDispatch
       end
 
       def test_required_part_in_recall
-        add_routes @router, [ "/messages/:a/:b" ]
+        mapper.get "/messages/:a/:b", to: "foo#bar"
 
-        path, _ = @formatter.generate(nil, { :a => 'a' }, { :b => 'b' })
+        path, _ = @formatter.generate(nil, { :controller => "foo", :action => "bar", :a => 'a' }, { :b => 'b' })
         assert_equal "/messages/a/b", path
       end
 
       def test_splat_in_recall
-        add_routes @router, [ "/*path" ]
+        mapper.get "/*path", to: "foo#bar"
 
-        path, _ = @formatter.generate(nil, { }, { :path => 'b' })
+        path, _ = @formatter.generate(nil, { :controller => "foo", :action => "bar" }, { :path => 'b' })
         assert_equal "/b", path
       end
 
       def test_recall_should_be_used_when_scoring
-        add_routes @router, [
-          "/messages/:action(/:id(.:format))",
-          "/messages/:id(.:format)"
-        ]
+        mapper.get "/messages/:action(/:id(.:format))", to: 'foo#bar'
+        mapper.get "/messages/:id(.:format)", to: 'bar#baz'
 
-        path, _ = @formatter.generate(nil, { :id => 10 }, { :action => 'index' })
+        path, _ = @formatter.generate(nil, { :controller => "foo", :id => 10 }, { :action => 'index' })
         assert_equal "/messages/index/10", path
       end
 
       def test_nil_path_parts_are_ignored
-        path  = Path::Pattern.from_string "/:controller(/:action(.:format))"
-        @router.routes.add_route @app, path, {}, {}, {}
+        mapper.get "/:controller(/:action(.:format))", to: "tasks#lol"
 
         params = { :controller => "tasks", :format => nil }
         extras = { :action => 'lol' }
@@ -329,18 +220,14 @@ module ActionDispatch
       def test_generate_slash
         params = [ [:controller, "tasks"],
                    [:action, "show"] ]
-        str = Router::Strexp.build("/", Hash[params], ['/', '.', '?'], true)
-        path  = Path::Pattern.new str
-
-        @router.routes.add_route @app, path, {}, {}, {}
+        mapper.get "/", Hash[params]
 
         path, _ = @formatter.generate(nil, Hash[params], {})
         assert_equal '/', path
       end
 
       def test_generate_calls_param_proc
-        path  = Path::Pattern.from_string '/:controller(/:action)'
-        @router.routes.add_route @app, path, {}, {}, {}
+        mapper.get '/:controller(/:action)', to: "foo#bar"
 
         parameterized = []
         params = [ [:controller, "tasks"],
@@ -356,8 +243,7 @@ module ActionDispatch
       end
 
       def test_generate_id
-        path  = Path::Pattern.from_string '/:controller(/:action)'
-        @router.routes.add_route @app, path, {}, {}, {}
+        mapper.get '/:controller(/:action)', to: 'foo#bar'
 
         path, params = @formatter.generate(
           nil, {:id=>1, :controller=>"tasks", :action=>"show"}, {})
@@ -366,8 +252,7 @@ module ActionDispatch
       end
 
       def test_generate_escapes
-        path  = Path::Pattern.from_string '/:controller(/:action)'
-        @router.routes.add_route @app, path, {}, {}, {}
+        mapper.get '/:controller(/:action)', to: "foo#bar"
 
         path, _ = @formatter.generate(nil,
           { :controller        => "tasks",
@@ -377,8 +262,7 @@ module ActionDispatch
       end
 
       def test_generate_escapes_with_namespaced_controller
-        path  = Path::Pattern.from_string '/:controller(/:action)'
-        @router.routes.add_route @app, path, {}, {}, {}
+        mapper.get '/:controller(/:action)', to: "foo#bar"
 
         path, _ = @formatter.generate(
           nil, { :controller        => "admin/tasks",
@@ -388,8 +272,7 @@ module ActionDispatch
       end
 
       def test_generate_extra_params
-        path  = Path::Pattern.from_string '/:controller(/:action)'
-        @router.routes.add_route @app, path, {}, {}, {}
+        mapper.get '/:controller(/:action)', to: "foo#bar"
 
         path, params = @formatter.generate(
           nil, { :id                => 1,
@@ -401,9 +284,34 @@ module ActionDispatch
         assert_equal({:id => 1, :relative_url_root => nil}, params)
       end
 
+      def test_generate_missing_keys_no_matches_different_format_keys
+        mapper.get '/:controller/:action/:name', to: "foo#bar"
+        primarty_parameters = {
+          :id                => 1,
+          :controller        => "tasks",
+          :action            => "show",
+          :relative_url_root => nil
+        }
+        redirection_parameters = {
+          'action'=>'show',
+        }
+        missing_key = 'name'
+        missing_parameters ={
+          missing_key => "task_1"
+        }
+        request_parameters = primarty_parameters.merge(redirection_parameters).merge(missing_parameters)
+
+        message = "No route matches #{Hash[request_parameters.sort_by{|k,v|k.to_s}].inspect} missing required keys: #{[missing_key.to_sym].inspect}"
+
+        error = assert_raises(ActionController::UrlGenerationError) do
+          @formatter.generate(
+            nil, request_parameters, request_parameters)
+        end
+        assert_equal message, error.message
+      end
+
       def test_generate_uses_recall_if_needed
-        path  = Path::Pattern.from_string '/:controller(/:action(/:id))'
-        @router.routes.add_route @app, path, {}, {}, {}
+        mapper.get '/:controller(/:action(/:id))', to: "foo#bar"
 
         path, params = @formatter.generate(
           nil,
@@ -414,8 +322,7 @@ module ActionDispatch
       end
 
       def test_generate_with_name
-        path  = Path::Pattern.from_string '/:controller(/:action)'
-        @router.routes.add_route @app, path, {}, {}, "tasks"
+        mapper.get '/:controller(/:action)', to: 'foo#bar', as: 'tasks'
 
         path, params = @formatter.generate(
           "tasks",
@@ -431,16 +338,15 @@ module ActionDispatch
         '/content/show/10'  => { :controller => 'content', :action => 'show', :id => "10" },
       }.each do |request_path, expected|
         define_method("test_recognize_#{expected.keys.map(&:to_s).join('_')}") do
-          path  = Path::Pattern.from_string "/:controller(/:action(/:id))"
-          app   = Object.new
-          route = @router.routes.add_route(app, path, {}, {}, {})
+          mapper.get "/:controller(/:action(/:id))", to: 'foo#bar'
+          route = @routes.first
 
           env = rails_env 'PATH_INFO' => request_path
           called   = false
 
           @router.recognize(env) do |r, params|
             assert_equal route, r
-            assert_equal(expected, params)
+            assert_equal({ :action => "bar" }.merge(expected), params)
             called = true
           end
 
@@ -453,16 +359,15 @@ module ActionDispatch
         :splat   => ['/segment/a/b%20c+d', { :segment => 'segment', :splat => 'a/b c+d' }]
       }.each do |name, (request_path, expected)|
         define_method("test_recognize_#{name}") do
-          path  = Path::Pattern.from_string '/:segment/*splat'
-          app   = Object.new
-          route = @router.routes.add_route(app, path, {}, {}, {})
+          mapper.get '/:segment/*splat', to: 'foo#bar'
 
           env = rails_env 'PATH_INFO' => request_path
           called   = false
+          route = @routes.first
 
           @router.recognize(env) do |r, params|
             assert_equal route, r
-            assert_equal(expected, params)
+            assert_equal(expected.merge(:controller=>"foo", :action=>"bar"), params)
             called = true
           end
 
@@ -471,14 +376,8 @@ module ActionDispatch
       end
 
       def test_namespaced_controller
-        strexp = Router::Strexp.build(
-          "/:controller(/:action(/:id))",
-          { :controller => /.+?/ },
-          ["/", ".", "?"]
-        )
-        path  = Path::Pattern.new strexp
-        app   = Object.new
-        route = @router.routes.add_route(app, path, {}, {}, {})
+        mapper.get "/:controller(/:action(/:id))", { :controller => /.+?/ }
+        route = @routes.first
 
         env = rails_env 'PATH_INFO' => '/admin/users/show/10'
         called   = false
@@ -497,9 +396,8 @@ module ActionDispatch
       end
 
       def test_recognize_literal
-        path   = Path::Pattern.from_string "/books(/:action(.:format))"
-        app    = Object.new
-        route  = @router.routes.add_route(app, path, {}, {:controller => 'books'})
+        mapper.get "/books(/:action(.:format))", controller: "books"
+        route = @routes.first
 
         env    = rails_env 'PATH_INFO' => '/books/list.rss'
         expected = { :controller => 'books', :action => 'list', :format => 'rss' }
@@ -514,10 +412,7 @@ module ActionDispatch
       end
 
       def test_recognize_head_route
-        path   = Path::Pattern.from_string "/books(/:action(.:format))"
-        app    = Object.new
-        conditions = { request_method: 'HEAD' }
-        @router.routes.add_route(app, path, conditions, {})
+        mapper.match "/books(/:action(.:format))", via: 'head', to: 'foo#bar'
 
         env = rails_env(
           'PATH_INFO' => '/books/list.rss',
@@ -533,12 +428,7 @@ module ActionDispatch
       end
 
       def test_recognize_head_request_as_get_route
-        path   = Path::Pattern.from_string "/books(/:action(.:format))"
-        app    = Object.new
-        conditions = {
-          :request_method => 'GET'
-        }
-        @router.routes.add_route(app, path, conditions, {})
+        mapper.get "/books(/:action(.:format))", to: 'foo#bar'
 
         env = rails_env 'PATH_INFO' => '/books/list.rss',
                         "REQUEST_METHOD"    => "HEAD"
@@ -551,11 +441,8 @@ module ActionDispatch
         assert called
       end
 
-      def test_recognize_cares_about_verbs
-        path   = Path::Pattern.from_string "/books(/:action(.:format))"
-        app    = Object.new
-        conditions = { request_method: 'GET' }
-        @router.routes.add_route(app, path, conditions, {})
+      def test_recognize_cares_about_get_verbs
+        mapper.match "/books(/:action(.:format))", to: "foo#bar", via: :get
 
         env = rails_env 'PATH_INFO' => '/books/list.rss',
                         "REQUEST_METHOD" => "POST"
@@ -566,34 +453,50 @@ module ActionDispatch
         end
 
         assert_not called
+      end
 
-        conditions = conditions.dup
-        conditions[:request_method] = 'POST'
+      def test_recognize_cares_about_post_verbs
+        mapper.match "/books(/:action(.:format))", to: "foo#bar", via: :post
 
-        post = @router.routes.add_route(app, path, conditions, {})
+        env = rails_env 'PATH_INFO' => '/books/list.rss',
+                        "REQUEST_METHOD" => "POST"
 
         called = false
         @router.recognize(env) do |r, params|
-          assert_equal post, r
           called = true
         end
 
         assert called
       end
 
-      private
+      def test_multi_verb_recognition
+        mapper.match "/books(/:action(.:format))", to: "foo#bar", via: [:post, :get]
+
+        %w( POST GET ).each do |verb|
+          env = rails_env 'PATH_INFO' => '/books/list.rss',
+            "REQUEST_METHOD" => verb
 
-      def add_routes router, paths
-        paths.each do |path|
-          if String === path
-            path  = Path::Pattern.from_string path
-          else
-            path  = Path::Pattern.new path
+          called = false
+          @router.recognize(env) do |r, params|
+            called = true
           end
-          router.routes.add_route @app, path, {}, {}, {}
+
+          assert called
+        end
+
+        env = rails_env 'PATH_INFO' => '/books/list.rss',
+          "REQUEST_METHOD" => 'PUT'
+
+        called = false
+        @router.recognize(env) do |r, params|
+          called = true
         end
+
+        assert_not called
       end
 
+      private
+
       def rails_env env, klass = ActionDispatch::Request
         klass.new(rack_env(env))
       end
diff --git a/actionpack/test/journey/routes_test.rb b/actionpack/test/journey/routes_test.rb
index a4efc82b8c..f8293dfc5f 100644
--- a/actionpack/test/journey/routes_test.rb
+++ b/actionpack/test/journey/routes_test.rb
@@ -3,50 +3,57 @@ require 'abstract_unit'
 module ActionDispatch
   module Journey
     class TestRoutes < ActiveSupport::TestCase
-      def test_clear
-        routes = Routes.new
-        exp    = Router::Strexp.build '/foo(/:id)', {}, ['/.?']
-        path   = Path::Pattern.new exp
-        requirements = { :hello => /world/ }
+      attr_reader :routes, :mapper
+
+      def setup
+        @route_set  = ActionDispatch::Routing::RouteSet.new
+        @routes = @route_set.router.routes
+        @router = @route_set.router
+        @mapper = ActionDispatch::Routing::Mapper.new @route_set
+        super
+      end
 
-        routes.add_route nil, path, requirements, {:id => nil}, {}
+      def test_clear
+        mapper.get "/foo(/:id)", to: "foo#bar", as: 'aaron'
+        assert_not_predicate routes, :empty?
         assert_equal 1, routes.length
 
         routes.clear
+        assert routes.empty?
         assert_equal 0, routes.length
       end
 
       def test_ast
-        routes = Routes.new
-        path   = Path::Pattern.from_string '/hello'
-
-        routes.add_route nil, path, {}, {}, {}
+        mapper.get "/foo(/:id)", to: "foo#bar", as: 'aaron'
         ast = routes.ast
-        routes.add_route nil, path, {}, {}, {}
+        mapper.get "/foo(/:id)", to: "foo#bar", as: 'gorby'
         assert_not_equal ast, routes.ast
       end
 
       def test_simulator_changes
-        routes = Routes.new
-        path   = Path::Pattern.from_string '/hello'
-
-        routes.add_route nil, path, {}, {}, {}
+        mapper.get "/foo(/:id)", to: "foo#bar", as: 'aaron'
         sim = routes.simulator
-        routes.add_route nil, path, {}, {}, {}
+        mapper.get "/foo(/:id)", to: "foo#bar", as: 'gorby'
         assert_not_equal sim, routes.simulator
       end
 
-      def test_first_name_wins
-        #def add_route app, path, conditions, defaults, name = nil
-        routes = Routes.new
+      def test_partition_route
+        mapper.get "/foo(/:id)", to: "foo#bar", as: 'aaron'
+
+        assert_equal 1, @routes.anchored_routes.length
+        assert_predicate @routes.custom_routes, :empty?
 
-        one   = Path::Pattern.from_string '/hello'
-        two   = Path::Pattern.from_string '/aaron'
+        mapper.get "/hello/:who", to: "foo#bar", as: 'bar', who: /\d/
 
-        routes.add_route nil, one, {}, {}, 'aaron'
-        routes.add_route nil, two, {}, {}, 'aaron'
+        assert_equal 1, @routes.custom_routes.length
+        assert_equal 1, @routes.anchored_routes.length
+      end
 
-        assert_equal '/hello', routes.named_routes['aaron'].path.spec.to_s
+      def test_first_name_wins
+        mapper.get "/hello", to: "foo#bar", as: 'aaron'
+        assert_raise(ArgumentError) do
+          mapper.get "/aaron", to: "foo#bar", as: 'aaron'
+        end
       end
     end
   end
diff --git a/actionview/CHANGELOG.md b/actionview/CHANGELOG.md
index a63eced6ab..c010b7ce91 100644
--- a/actionview/CHANGELOG.md
+++ b/actionview/CHANGELOG.md
@@ -1,3 +1,179 @@
+*   Collection input propagates input's `id` to the label's `for` attribute when
+    using html options as the last element of collection.
+
+    *Vasiliy Ermolovich*
+
+*   Add a `hidden_field` on the `collection_radio_buttons` to avoid raising a error
+    when the only input on the form is the `collection_radio_buttons`.
+
+    *Mauro George*
+
+*   `url_for` does not modify its arguments when generating polymorphic URLs.
+
+    *Bernerd Schaefer*
+
+*   `number_to_currency` and `number_with_delimiter` now accept custom `delimiter_pattern` option 
+     to handle placement of delimiter, to support currency formats like INR 
+     
+     Example: 
+        
+        number_to_currency(1230000, delimiter_pattern: /(\d+?)(?=(\d\d)+(\d)(?!\d))/, unit: '₹', format: "%u %n")
+        # => '₹ 12,30,000.00' 
+        
+    *Vipul A M*
+    
+*   Make `disable_with` the default behavior for submit tags. Disables the
+    button on submit to prevent double submits.
+
+    *Justin Schiff*
+
+*   Add a break_sequence option to word_wrap so you can specify a custom break.
+
+    * Mauricio Gomez *
+
+*   Add wildcard matching to explicit dependencies.
+
+    Turns:
+
+    ```erb
+    <% # Template Dependency: recordings/threads/events/subscribers_changed %>
+    <% # Template Dependency: recordings/threads/events/completed %>
+    <% # Template Dependency: recordings/threads/events/uncompleted %>
+    ```
+
+    Into:
+
+    ```erb
+    <% # Template Dependency: recordings/threads/events/* %>
+    ```
+
+    *Kasper Timm Hansen*
+
+*   Allow defining explicit collection caching using a `# Template Collection: ...`
+    directive inside templates.
+
+    *Dov Murik*
+
+*   Asset helpers raise `ArgumentError` when `nil` is passed as a source.
+
+    *Anton Kolomiychuk*
+
+*   Always attach the template digest to the cache key for collection caching
+    even when `virtual_path` is not available from the view context.
+    Which could happen if the rendering was done directly in the controller
+    and not in a template.
+
+    Fixes #20535
+
+    *Roque Pinel*
+
+*   Improve detection of partial templates eligible for collection caching,
+    now allowing multi-line comments at the beginning of the template file.
+
+    *Dov Murik*
+
+*   Raise an ArgumentError when a false value for `include_blank` is passed to a
+    required select field (to comply with the HTML5 spec).
+
+    *Grey Baker*
+
+*   Do not put partial name to `local_assigns` when rendering without
+    an object or a collection.
+
+    *Henrik Nygren*
+
+*   Remove `:rescue_format` option for `translate` helper since it's no longer
+    supported by I18n.
+
+    *Bernard Potocki*
+
+*   `translate` should handle `raise` flag correctly in case of both main and default
+    translation is missing.
+
+    Fixes #19967
+
+    *Bernard Potocki*
+
+*   Load the `default_form_builder` from the controller on initialization, which overrides
+    the global config if it is present.
+
+    *Kevin McPhillips*
+
+*   Accept lambda as `child_index` option in `fields_for` method.
+
+    *Karol Galanciak*
+
+*   `translate` allows `default: [[]]` again for a default value of `[]`.
+
+    Fixes #19640.
+
+    *Adam Prescott*
+
+*   `translate` should accept nils as members of the `:default`
+    parameter without raising a translation missing error.
+
+    Fixes #19419
+
+    *Justin Coyne*
+
+*   `number_to_percentage` does not crash with `Float::NAN` or `Float::INFINITY`
+    as input when `precision: 0` is used.
+
+    Fixes #19227.
+
+    *Yves Senn*
+
+*   Fixed the translation helper method to accept different default values types
+    besides String.
+
+    *Ulisses Almeida*
+
+*   Collection rendering automatically caches and fetches multiple partials.
+
+    Collections rendered as:
+
+    ```ruby
+    <%= render @notifications %>
+    <%= render partial: 'notifications/notification', collection: @notifications, as: :notification %>
+    ```
+
+    will now read several partials from cache at once, if the template starts with a cache call:
+
+    ```ruby
+    # notifications/_notification.html.erb
+    <% cache notification do %>
+      <%# ... %>
+    <% end %>
+    ```
+
+    *Kasper Timm Hansen*
+
+*   Fixed a dependency tracker bug that caused template dependencies not
+    count layouts as dependencies for partials.
+
+    *Juho Leinonen*
+
+*   Extracted `ActionView::Helpers::RecordTagHelper` to external gem
+    (`record_tag_helper`) and added removal notices.
+
+    *Todd Bealmear*
+
+*   Allow to pass a string value to `size` option in `image_tag` and `video_tag`.
+
+    This makes the behavior more consistent with `width` or `height` options.
+
+    *Mehdi Lahmam*
+
+*   Partial template name does no more have to be a valid Ruby identifier.
+
+    There used to be a naming rule that the partial name should start with
+    underscore, and should be followed by any combination of letters, numbers
+    and underscores.
+    But now we can give our partials any name starting with underscore, such as
+    _🍔.html.erb.
+
+    *Akira Matsuda*
+
 *   Change the default template handler from `ERB` to `Raw`.
 
     Files without a template handler in their extension will be rendered using the raw
@@ -18,7 +194,7 @@
 
     *Nikolay Shebanov*
 
-*   Add a `hidden_field` on the `file_field` to avoid raise a error when the only
+*   Add a `hidden_field` on the `file_field` to avoid raising an error when the only
     input on the form is the `file_field`.
 
     *Mauro George*
@@ -28,5 +204,8 @@
 
     *Angelo Capilleri*
 
+*   Allow entries without a link tag in `AtomFeedHelper`.
+
+    *Daniel Gomez de Souza*
 
 Please check [4-2-stable](https://github.com/rails/rails/blob/4-2-stable/actionview/CHANGELOG.md) for previous changes.
diff --git a/actionview/README.rdoc b/actionview/README.rdoc
index 5bb62c7562..8b1f85f748 100644
--- a/actionview/README.rdoc
+++ b/actionview/README.rdoc
@@ -9,7 +9,7 @@ used to inline short Ruby snippets inside HTML), and XML Builder.
 
 The latest version of Action View can be installed with RubyGems:
 
-  % [sudo] gem install actionview
+  % gem install actionview
 
 Source code can be downloaded as part of the Rails project on GitHub
 
diff --git a/actionview/Rakefile b/actionview/Rakefile
index 1b71435948..93be50721d 100644
--- a/actionview/Rakefile
+++ b/actionview/Rakefile
@@ -1,5 +1,4 @@
 require 'rake/testtask'
-require 'rubygems/package_task'
 
 desc "Default Task"
 task :default => :test
@@ -18,7 +17,7 @@ namespace :test do
 
   Rake::TestTask.new(:template) do |t|
     t.libs << 'test'
-    t.test_files = Dir.glob('test/template/**/*_test.rb').sort
+    t.test_files = Dir.glob('test/template/**/*_test.rb')
     t.warning = true
     t.verbose = true
     t.ruby_opts = ["--dev"] if defined?(JRUBY_VERSION)
@@ -45,39 +44,8 @@ namespace :test do
   end
 end
 
-spec = eval(File.read('actionview.gemspec'))
-
-Gem::PackageTask.new(spec) do |p|
-  p.gem_spec = spec
-end
-
-desc "Release to rubygems"
-task :release => :package do
-  require 'rake/gemcutter'
-  Rake::Gemcutter::Tasks.new(spec).define
-  Rake::Task['gem:push'].invoke
-end
-
 task :lines do
-  lines, codelines, total_lines, total_codelines = 0, 0, 0, 0
-
-  FileList["lib/**/*.rb"].each do |file_name|
-    next if file_name =~ /vendor/
-    File.open(file_name, 'r') do |f|
-      while line = f.gets
-        lines += 1
-        next if line =~ /^\s*$/
-        next if line =~ /^\s*#/
-        codelines += 1
-      end
-    end
-    puts "L: #{sprintf("%4d", lines)}, LOC #{sprintf("%4d", codelines)} | #{file_name}"
-
-    total_lines     += lines
-    total_codelines += codelines
-
-    lines, codelines = 0, 0
-  end
-
-  puts "Total: Lines #{total_lines}, LOC #{total_codelines}"
+  load File.expand_path('..', File.dirname(__FILE__)) + '/tools/line_statistics'
+  files = FileList["lib/**/*.rb"]
+  CodeTools::LineStatistics.new(files).print_loc
 end
diff --git a/actionview/actionview.gemspec b/actionview/actionview.gemspec
index 8f9194cda7..612e94021d 100644
--- a/actionview/actionview.gemspec
+++ b/actionview/actionview.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'Rendering framework putting the V in MVC (part of Rails).'
   s.description = 'Simple, battle-tested conventions and helpers for building web pages.'
 
-  s.required_ruby_version = '>= 2.2.0'
+  s.required_ruby_version = '>= 2.2.2'
 
   s.license     = 'MIT'
 
@@ -23,7 +23,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'builder',       '~> 3.1'
   s.add_dependency 'erubis',        '~> 2.7.0'
-  s.add_dependency 'rails-html-sanitizer', '~> 1.0', '>= 1.0.1'
+  s.add_dependency 'rails-html-sanitizer', '~> 1.0', '>= 1.0.2'
   s.add_dependency 'rails-dom-testing', '~> 1.0', '>= 1.0.5'
 
   s.add_development_dependency 'actionpack',  version
diff --git a/actionview/bin/test b/actionview/bin/test
new file mode 100755
index 0000000000..404cabba51
--- /dev/null
+++ b/actionview/bin/test
@@ -0,0 +1,4 @@
+#!/usr/bin/env ruby
+COMPONENT_ROOT = File.expand_path("../../", __FILE__)
+require File.expand_path("../tools/test", COMPONENT_ROOT)
+exit Minitest.run(ARGV)
diff --git a/actionview/lib/action_view/base.rb b/actionview/lib/action_view/base.rb
index 1feafc1094..ad1cb1a4be 100644
--- a/actionview/lib/action_view/base.rb
+++ b/actionview/lib/action_view/base.rb
@@ -70,6 +70,14 @@ module ActionView #:nodoc:
   #   Headline: <%= headline %>
   #   First name: <%= person.first_name %>
   #
+  # The local variables passed to sub templates can be accessed as a hash using the <tt>local_assigns</tt> hash. This lets you access the
+  # variables as:
+  #
+  #   Headline: <%= local_assigns[:headline] %>
+  #
+  # This is useful in cases where you aren't sure if the local variable has been assigned. Alternatively, you could also use
+  # <tt>defined? headline</tt> to first check if the variable has been assigned before using it.
+  #
   # === Template caching
   #
   # By default, Rails will compile each template to a method in order to render it. When you alter a template,
@@ -153,6 +161,10 @@ module ActionView #:nodoc:
     cattr_accessor :raise_on_missing_translations
     @@raise_on_missing_translations = false
 
+    # Specify whether submit_tag should automatically disable on click
+    cattr_accessor :automatically_disable_submit_tag
+    @@automatically_disable_submit_tag = true
+
     class_attribute :_routes
     class_attribute :logger
 
diff --git a/actionview/lib/action_view/dependency_tracker.rb b/actionview/lib/action_view/dependency_tracker.rb
index e34bdd4a46..7716955fd9 100644
--- a/actionview/lib/action_view/dependency_tracker.rb
+++ b/actionview/lib/action_view/dependency_tracker.rb
@@ -1,16 +1,18 @@
-require 'thread_safe'
+require 'concurrent'
+require 'action_view/path_set'
 
 module ActionView
   class DependencyTracker # :nodoc:
-    @trackers = ThreadSafe::Cache.new
+    @trackers = Concurrent::Map.new
 
-    def self.find_dependencies(name, template)
+    def self.find_dependencies(name, template, view_paths = nil)
       tracker = @trackers[template.handler]
+      return [] unless tracker.present?
 
-      if tracker.present?
-        tracker.call(name, template)
+      if tracker.respond_to?(:supports_view_paths?) && tracker.supports_view_paths?
+        tracker.call(name, template, view_paths)
       else
-        []
+        tracker.call(name, template)
       end
     end
 
@@ -76,12 +78,22 @@ module ActionView
         (?:#{STRING}|#{VARIABLE_OR_METHOD_CHAIN})      # finally, the dependency name of interest
       /xm
 
-      def self.call(name, template)
-        new(name, template).dependencies
+      LAYOUT_DEPENDENCY = /\A
+        (?:\s*\(?\s*)                                  # optional opening paren surrounded by spaces
+        (?:.*?#{LAYOUT_HASH_KEY})                      # check if the line has layout key declaration
+        (?:#{STRING}|#{VARIABLE_OR_METHOD_CHAIN})      # finally, the dependency name of interest
+      /xm
+
+      def self.supports_view_paths? # :nodoc:
+        true
+      end
+
+      def self.call(name, template, view_paths = nil)
+        new(name, template, view_paths).dependencies
       end
 
-      def initialize(name, template)
-        @name, @template = name, template
+      def initialize(name, template, view_paths = nil)
+        @name, @template, @view_paths = name, template, view_paths
       end
 
       def dependencies
@@ -106,15 +118,20 @@ module ActionView
           render_calls = source.split(/\brender\b/).drop(1)
 
           render_calls.each do |arguments|
-            arguments.scan(RENDER_ARGUMENTS) do
-              add_dynamic_dependency(render_dependencies, Regexp.last_match[:dynamic])
-              add_static_dependency(render_dependencies, Regexp.last_match[:static])
-            end
+            add_dependencies(render_dependencies, arguments, LAYOUT_DEPENDENCY)
+            add_dependencies(render_dependencies, arguments, RENDER_ARGUMENTS)
           end
 
           render_dependencies.uniq
         end
 
+        def add_dependencies(render_dependencies, arguments, pattern)
+          arguments.scan(pattern) do
+            add_dynamic_dependency(render_dependencies, Regexp.last_match[:dynamic])
+            add_static_dependency(render_dependencies, Regexp.last_match[:static])
+          end
+        end
+
         def add_dynamic_dependency(dependencies, dependency)
           if dependency
             dependencies << "#{dependency.pluralize}/#{dependency.singularize}"
@@ -131,8 +148,22 @@ module ActionView
           end
         end
 
+        def resolve_directories(wildcard_dependencies)
+          return [] unless @view_paths
+
+          wildcard_dependencies.each_with_object([]) do |query, templates|
+            @view_paths.find_all_with_query(query).each do |template|
+              templates << "#{File.dirname(query)}/#{File.basename(template).split('.').first}"
+            end
+          end
+        end
+
         def explicit_dependencies
-          source.scan(EXPLICIT_DEPENDENCY).flatten.uniq
+          dependencies = source.scan(EXPLICIT_DEPENDENCY).flatten.uniq
+
+          wildcards, explicits = dependencies.partition { |dependency| dependency[-1] == '*' }
+
+          (explicits + resolve_directories(wildcards)).uniq
         end
     end
 
diff --git a/actionview/lib/action_view/digestor.rb b/actionview/lib/action_view/digestor.rb
index 1f103786cb..12e9723a02 100644
--- a/actionview/lib/action_view/digestor.rb
+++ b/actionview/lib/action_view/digestor.rb
@@ -1,18 +1,25 @@
-require 'thread_safe'
+require 'concurrent'
 require 'action_view/dependency_tracker'
 require 'monitor'
 
 module ActionView
   class Digestor
     cattr_reader(:cache)
-    @@cache          = ThreadSafe::Cache.new
+    @@cache          = Concurrent::Map.new
     @@digest_monitor = Monitor.new
 
+    class PerRequestDigestCacheExpiry < Struct.new(:app) # :nodoc:
+      def call(env)
+        ActionView::Digestor.cache.clear
+        app.call(env)
+      end
+    end
+
     class << self
       # Supported options:
       #
       # * <tt>name</tt>   - Template name
-      # * <tt>finder</tt>  - An instance of ActionView::LookupContext
+      # * <tt>finder</tt>  - An instance of <tt>ActionView::LookupContext</tt>
       # * <tt>dependencies</tt>  - An array of dependent views
       # * <tt>partial</tt>  - Specifies whether the template is a partial
       def digest(options)
@@ -21,7 +28,7 @@ module ActionView
         cache_key = ([ options[:name], options[:finder].details_key.hash ].compact + Array.wrap(options[:dependencies])).join('.')
 
         # this is a correctly done double-checked locking idiom
-        # (ThreadSafe::Cache's lookups have volatile semantics)
+        # (Concurrent::Map's lookups have volatile semantics)
         @@cache[cache_key] || @@digest_monitor.synchronize do
           @@cache.fetch(cache_key) do # re-check under lock
             compute_and_store_digest(cache_key, options)
@@ -41,10 +48,7 @@ module ActionView
             Digestor
           end
 
-          digest = klass.new(options).digest
-          # Store the actual digest if config.cache_template_loading is true
-          @@cache[cache_key] = stored_digest = digest if ActionView::Resolver.caching?
-          digest
+          @@cache[cache_key] = stored_digest = klass.new(options).digest
         ensure
           # something went wrong or ActionView::Resolver.caching? is false, make sure not to corrupt the @@cache
           @@cache.delete_pair(cache_key, false) if pre_stored && !stored_digest
@@ -68,9 +72,10 @@ module ActionView
     end
 
     def dependencies
-      DependencyTracker.find_dependencies(name, template)
+      DependencyTracker.find_dependencies(name, template, finder.view_paths)
     rescue ActionView::MissingTemplate
-      [] # File doesn't exist, so no dependencies
+      logger.try :error, "  '#{name}' file doesn't exist, so no dependencies"
+      []
     end
 
     def nested_dependencies
diff --git a/actionview/lib/action_view/helpers/asset_tag_helper.rb b/actionview/lib/action_view/helpers/asset_tag_helper.rb
index b7fdc16a9d..fa46a22500 100644
--- a/actionview/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionview/lib/action_view/helpers/asset_tag_helper.rb
@@ -60,7 +60,7 @@ module ActionView
           tag_options = {
             "src" => path_to_javascript(source, path_options)
           }.merge!(options)
-          content_tag(:script, "", tag_options)
+          content_tag("script".freeze, "", tag_options)
         }.join("\n").html_safe
       end
 
@@ -127,7 +127,7 @@ module ActionView
       #   auto_discovery_link_tag(:rss, {controller: "news", action: "feed"})
       #   # => <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/news/feed" />
       #   auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", {title: "Example RSS"})
-      #   # => <link rel="alternate" type="application/rss+xml" title="Example RSS" href="http://www.example.com/feed" />
+      #   # => <link rel="alternate" type="application/rss+xml" title="Example RSS" href="http://www.example.com/feed.rss" />
       def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})
         if !(type == :rss || type == :atom) && tag_options[:type].blank?
           raise ArgumentError.new("You should pass :type tag_option key explicitly, because you have passed #{type} type other than :rss or :atom.")
@@ -136,7 +136,7 @@ module ActionView
         tag(
           "link",
           "rel"   => tag_options[:rel] || "alternate",
-          "type"  => tag_options[:type] || Mime::Type.lookup_by_extension(type.to_s).to_s,
+          "type"  => tag_options[:type] || Mime[type].to_s,
           "title" => tag_options[:title] || type.to_s.upcase,
           "href"  => url_options.is_a?(Hash) ? url_for(url_options.merge(:only_path => false)) : url_options
         )
@@ -207,6 +207,7 @@ module ActionView
       #   # => <img alt="Icon" class="menu_icon" src="/icons/icon.gif" />
       def image_tag(source, options={})
         options = options.symbolize_keys
+        check_for_image_tag_errors(options)
 
         src = options[:src] = path_to_image(source)
 
@@ -236,7 +237,7 @@ module ActionView
       #   image_alt('underscored_file_name.png')
       #   # => Underscored file name
       def image_alt(src)
-        File.basename(src, '.*').sub(/-[[:xdigit:]]{32}\z/, '').tr('-_', ' ').capitalize
+        File.basename(src, '.*'.freeze).sub(/-[[:xdigit:]]{32}\z/, ''.freeze).tr('-_'.freeze, ' '.freeze).capitalize
       end
 
       # Returns an HTML video tag for the +sources+. If +sources+ is a string,
@@ -318,12 +319,19 @@ module ActionView
         end
 
         def extract_dimensions(size)
+          size = size.to_s
           if size =~ %r{\A\d+x\d+\z}
             size.split('x')
           elsif size =~ %r{\A\d+\z}
             [size, size]
           end
         end
+
+        def check_for_image_tag_errors(options)
+          if options[:size] && (options[:height] || options[:width])
+            raise ArgumentError, "Cannot pass a :size option with a :height or :width option"
+          end
+        end
     end
   end
 end
diff --git a/actionview/lib/action_view/helpers/asset_url_helper.rb b/actionview/lib/action_view/helpers/asset_url_helper.rb
index 29733442c1..717b326740 100644
--- a/actionview/lib/action_view/helpers/asset_url_helper.rb
+++ b/actionview/lib/action_view/helpers/asset_url_helper.rb
@@ -31,26 +31,33 @@ module ActionView
     #   stylesheet_link_tag("application")
     #   # => <link href="http://assets.example.com/assets/application.css" media="screen" rel="stylesheet" />
     #
-    # Browsers typically open at most two simultaneous connections to a single
-    # host, which means your assets often have to wait for other assets to finish
-    # downloading. You can alleviate this by using a <tt>%d</tt> wildcard in the
-    # +asset_host+. For example, "assets%d.example.com". If that wildcard is
-    # present Rails distributes asset requests among the corresponding four hosts
-    # "assets0.example.com", ..., "assets3.example.com". With this trick browsers
-    # will open eight simultaneous connections rather than two.
+    # Browsers open a limited number of simultaneous connections to a single
+    # host. The exact number varies by browser and version. This limit may cause
+    # some asset downloads to wait for previous assets to finish before they can
+    # begin. You can use the <tt>%d</tt> wildcard in the +asset_host+ to
+    # distribute the requests over four hosts. For example,
+    # <tt>assets%d.example.com<tt> will spread the asset requests over
+    # "assets0.example.com", ..., "assets3.example.com".
     #
     #   image_tag("rails.png")
     #   # => <img alt="Rails" src="http://assets0.example.com/assets/rails.png" />
     #   stylesheet_link_tag("application")
     #   # => <link href="http://assets2.example.com/assets/application.css" media="screen" rel="stylesheet" />
     #
-    # To do this, you can either setup four actual hosts, or you can use wildcard
-    # DNS to CNAME the wildcard to a single asset host. You can read more about
-    # setting up your DNS CNAME records from your ISP.
+    # This may improve the asset loading performance of your application.
+    # It is also possible the combination of additional connection overhead
+    # (DNS, SSL) and the overall browser connection limits may result in this
+    # solution being slower. You should be sure to measure your actual
+    # performance across targeted browsers both before and after this change.
+    #
+    # To implement the corresponding hosts you can either setup four actual
+    # hosts or use wildcard DNS to CNAME the wildcard to a single asset host.
+    # You can read more about setting up your DNS CNAME records from your ISP.
     #
     # Note: This is purely a browser performance optimization and is not meant
     # for server load balancing. See http://www.die.net/musings/page_load_time/
-    # for background.
+    # for background and http://www.browserscope.org/?category=network for
+    # connection limit data.
     #
     # Alternatively, you can exert more control over the asset host by setting
     # +asset_host+ to a proc like this:
@@ -121,11 +128,13 @@ module ActionView
       #   asset_path "application", type: :stylesheet     # => /assets/application.css
       #   asset_path "http://www.example.com/js/xmlhr.js" # => http://www.example.com/js/xmlhr.js
       def asset_path(source, options = {})
+        raise ArgumentError, "nil is not a valid asset source" if source.nil?
+
         source = source.to_s
         return "" unless source.present?
         return source if source =~ URI_REGEXP
 
-        tail, source = source[/([\?#].+)$/], source.sub(/([\?#].+)$/, '')
+        tail, source = source[/([\?#].+)$/], source.sub(/([\?#].+)$/, ''.freeze)
 
         if extname = compute_asset_extname(source, options)
           source = "#{source}#{extname}"
@@ -248,6 +257,11 @@ module ActionView
 
       # Computes the full URL to a JavaScript asset in the public javascripts directory.
       # This will use +javascript_path+ internally, so most of their behaviors will be the same.
+      # Since +javascript_url+ is based on +asset_url+ method you can set :host options. If :host
+      # options is set, it overwrites global +config.action_controller.asset_host+ setting.
+      #
+      #   javascript_url "js/xmlhr.js", host: "http://stage.example.com" # => http://stage.example.com/assets/dir/xmlhr.js
+      #
       def javascript_url(source, options = {})
         url_to_asset(source, {type: :javascript}.merge!(options))
       end
@@ -270,6 +284,11 @@ module ActionView
 
       # Computes the full URL to a stylesheet asset in the public stylesheets directory.
       # This will use +stylesheet_path+ internally, so most of their behaviors will be the same.
+      # Since +stylesheet_url+ is based on +asset_url+ method you can set :host options. If :host
+      # options is set, it overwrites global +config.action_controller.asset_host+ setting.
+      #
+      #   stylesheet_url "css/style.css", host: "http://stage.example.com" # => http://stage.example.com/css/style.css
+      #
       def stylesheet_url(source, options = {})
         url_to_asset(source, {type: :stylesheet}.merge!(options))
       end
@@ -295,6 +314,11 @@ module ActionView
 
       # Computes the full URL to an image asset.
       # This will use +image_path+ internally, so most of their behaviors will be the same.
+      # Since +image_url+ is based on +asset_url+ method you can set :host options. If :host
+      # options is set, it overwrites global +config.action_controller.asset_host+ setting.
+      #
+      #   image_url "edit.png", host: "http://stage.example.com" # => http://stage.example.com/edit.png
+      #
       def image_url(source, options = {})
         url_to_asset(source, {type: :image}.merge!(options))
       end
@@ -316,6 +340,11 @@ module ActionView
 
       # Computes the full URL to a video asset in the public videos directory.
       # This will use +video_path+ internally, so most of their behaviors will be the same.
+      # Since +video_url+ is based on +asset_url+ method you can set :host options. If :host
+      # options is set, it overwrites global +config.action_controller.asset_host+ setting.
+      #
+      #   video_url "hd.avi", host: "http://stage.example.com" # => http://stage.example.com/hd.avi
+      #
       def video_url(source, options = {})
         url_to_asset(source, {type: :video}.merge!(options))
       end
@@ -337,6 +366,11 @@ module ActionView
 
       # Computes the full URL to an audio asset in the public audios directory.
       # This will use +audio_path+ internally, so most of their behaviors will be the same.
+      # Since +audio_url+ is based on +asset_url+ method you can set :host options. If :host
+      # options is set, it overwrites global +config.action_controller.asset_host+ setting.
+      #
+      #   audio_url "horse.wav", host: "http://stage.example.com" # => http://stage.example.com/horse.wav
+      #
       def audio_url(source, options = {})
         url_to_asset(source, {type: :audio}.merge!(options))
       end
@@ -357,6 +391,11 @@ module ActionView
 
       # Computes the full URL to a font asset.
       # This will use +font_path+ internally, so most of their behaviors will be the same.
+      # Since +font_url+ is based on +asset_url+ method you can set :host options. If :host
+      # options is set, it overwrites global +config.action_controller.asset_host+ setting.
+      #
+      #   font_url "font.ttf", host: "http://stage.example.com" # => http://stage.example.com/font.ttf
+      #
       def font_url(source, options = {})
         url_to_asset(source, {type: :font}.merge!(options))
       end
diff --git a/actionview/lib/action_view/helpers/atom_feed_helper.rb b/actionview/lib/action_view/helpers/atom_feed_helper.rb
index 227ad4cdfa..bb1cdd0f8d 100644
--- a/actionview/lib/action_view/helpers/atom_feed_helper.rb
+++ b/actionview/lib/action_view/helpers/atom_feed_helper.rb
@@ -16,7 +16,7 @@ module ActionView
       #     end
       #
       #   app/controllers/posts_controller.rb:
-      #     class PostsController < ApplicationController::Base
+      #     class PostsController < ApplicationController
       #       # GET /posts.html
       #       # GET /posts.atom
       #       def index
@@ -51,7 +51,7 @@ module ActionView
       # * <tt>:language</tt>: Defaults to "en-US".
       # * <tt>:root_url</tt>: The HTML alternative that this feed is doubling for. Defaults to / on the current host.
       # * <tt>:url</tt>: The URL for this feed. Defaults to the current URL.
-      # * <tt>:id</tt>: The id for this feed. Defaults to "tag:#{request.host},#{options[:schema_date]}:#{request.fullpath.split(".")[0]}"
+      # * <tt>:id</tt>: The id for this feed. Defaults to "tag:localhost,2005:/posts", in this case. 
       # * <tt>:schema_date</tt>: The date at which the tag scheme for the feed was first used. A good default is the year you
       #   created the feed. See http://feedvalidator.org/docs/error/InvalidTAG.html for more information. If not specified,
       #   2005 is used (as an "I don't care" value).
@@ -174,7 +174,7 @@ module ActionView
         #
         # * <tt>:published</tt>: Time first published. Defaults to the created_at attribute on the record if one such exists.
         # * <tt>:updated</tt>: Time of update. Defaults to the updated_at attribute on the record if one such exists.
-        # * <tt>:url</tt>: The URL for this entry. Defaults to the polymorphic_url for the record.
+        # * <tt>:url</tt>: The URL for this entry or false or nil for not having a link tag. Defaults to the polymorphic_url for the record.
         # * <tt>:id</tt>: The ID for this entry. Defaults to "tag:#{@view.request.host},#{@feed_options[:schema_date]}:#{record.class}/#{record.id}"
         # * <tt>:type</tt>: The TYPE for this entry. Defaults to "text/html".
         def entry(record, options = {})
@@ -191,7 +191,8 @@ module ActionView
 
             type = options.fetch(:type, 'text/html')
 
-            @xml.link(:rel => 'alternate', :type => type, :href => options[:url] || @view.polymorphic_url(record))
+            url = options.fetch(:url) { @view.polymorphic_url(record) }
+            @xml.link(:rel => 'alternate', :type => type, :href => url) if url
 
             yield AtomBuilder.new(@xml)
           end
diff --git a/actionview/lib/action_view/helpers/cache_helper.rb b/actionview/lib/action_view/helpers/cache_helper.rb
index 4db8930a26..e473aeaea9 100644
--- a/actionview/lib/action_view/helpers/cache_helper.rb
+++ b/actionview/lib/action_view/helpers/cache_helper.rb
@@ -39,7 +39,7 @@ module ActionView
       # This will include both records as part of the cache key and updating either of them will
       # expire the cache.
       #
-      # ==== Template digest
+      # ==== \Template digest
       #
       # The template digest that's added to the cache key is computed by taking an md5 of the
       # contents of the entire template file. This ensures that your caches will automatically
@@ -75,7 +75,8 @@ module ActionView
       #   render(topics)         => render("topics/topic")
       #   render(message.topics) => render("topics/topic")
       #
-      # It's not possible to derive all render calls like that, though. Here are a few examples of things that can't be derived:
+      # It's not possible to derive all render calls like that, though.
+      # Here are a few examples of things that can't be derived:
       #
       #   render group_of_attachments
       #   render @project.documents.where(published: true).order('created_at')
@@ -97,21 +98,74 @@ module ActionView
       #   <%# Template Dependency: todolists/todolist %>
       #   <%= render_sortable_todolists @project.todolists %>
       #
-      # The pattern used to match these is /# Template Dependency: ([^ ]+)/, so it's important that you type it out just so.
+      # In some cases, like a single table inheritance setup, you might have
+      # a bunch of explicit dependencies. Instead of writing every template out,
+      # you can use a wildcard to match any template in a directory:
+      #
+      #   <%# Template Dependency: events/* %>
+      #   <%= render_categorizable_events @person.events %>
+      #
+      # This marks every template in the directory as a dependency. To find those
+      # templates, the wildcard path must be absolutely defined from app/views or paths
+      # otherwise added with +prepend_view_path+ or +append_view_path+.
+      # This way the wildcard for `app/views/recordings/events` would be `recordings/events/*` etc.
+      #
+      # The pattern used to match explicit dependencies is <tt>/# Template Dependency: (\S+)/</tt>,
+      # so it's important that you type it out just so.
       # You can only declare one template dependency per line.
       #
       # === External dependencies
       #
-      # If you use a helper method, for example, inside of a cached block and you then update that helper,
-      # you'll have to bump the cache as well. It doesn't really matter how you do it, but the md5 of the template file
+      # If you use a helper method, for example, inside a cached block and
+      # you then update that helper, you'll have to bump the cache as well.
+      # It doesn't really matter how you do it, but the md5 of the template file
       # must change. One recommendation is to simply be explicit in a comment, like:
       #
       #   <%# Helper Dependency Updated: May 6, 2012 at 6pm %>
       #   <%= some_helper_method(person) %>
       #
-      # Now all you'll have to do is change that timestamp when the helper method changes.
-      def cache(name = {}, options = nil, &block)
-        if controller.perform_caching
+      # Now all you have to do is change that timestamp when the helper method changes.
+      #
+      # === Automatic Collection Caching
+      #
+      # When rendering collections such as:
+      #
+      #   <%= render @notifications %>
+      #   <%= render partial: 'notifications/notification', collection: @notifications %>
+      #
+      # If the notifications/_notification partial starts with a cache call as:
+      #
+      #   <% cache notification do %>
+      #     <%= notification.name %>
+      #   <% end %>
+      #
+      # The collection can then automatically use any cached renders for that
+      # template by reading them at once instead of one by one.
+      #
+      # See ActionView::Template::Handlers::ERB.resource_cache_call_pattern for
+      # more information on what cache calls make a template eligible for this
+      # collection caching.
+      #
+      # The automatic cache multi read can be turned off like so:
+      #
+      #   <%= render @notifications, cache: false %>
+      #
+      # === Explicit Collection Caching
+      #
+      # If the partial template doesn't start with a clean cache call as
+      # mentioned above, you can still benefit from collection caching by
+      # adding a special comment format anywhere in the template, like:
+      #
+      #   <%# Template Collection: notification %>
+      #   <% my_helper_that_calls_cache(some_arg, notification) do %>
+      #     <%= notification.name %>
+      #   <% end %>
+      #
+      # The pattern used to match these is <tt>/# Template Collection: (\S+)/</tt>,
+      # so it's important that you type it out just so.
+      # You can only declare one collection in a partial template file.
+      def cache(name = {}, options = {}, &block)
+        if controller.respond_to?(:perform_caching) && controller.perform_caching
           safe_concat(fragment_for(cache_fragment_name(name, options), options, &block))
         else
           yield
@@ -122,11 +176,11 @@ module ActionView
 
       # Cache fragments of a view if +condition+ is true
       #
-      #   <%= cache_if admin?, project do %>
+      #   <% cache_if admin?, project do %>
       #     <b>All the topics on this project</b>
       #     <%= render project.topics %>
       #   <% end %>
-      def cache_if(condition, name = {}, options = nil, &block)
+      def cache_if(condition, name = {}, options = {}, &block)
         if condition
           cache(name, options, &block)
         else
@@ -138,37 +192,46 @@ module ActionView
 
       # Cache fragments of a view unless +condition+ is true
       #
-      #   <%= cache_unless admin?, project do %>
+      #   <% cache_unless admin?, project do %>
       #     <b>All the topics on this project</b>
       #     <%= render project.topics %>
       #   <% end %>
-      def cache_unless(condition, name = {}, options = nil, &block)
+      def cache_unless(condition, name = {}, options = {}, &block)
         cache_if !condition, name, options, &block
       end
 
       # This helper returns the name of a cache key for a given fragment cache
-      # call. By supplying skip_digest: true to cache, the digestion of cache
+      # call. By supplying +skip_digest:+ true to cache, the digestion of cache
       # fragments can be manually bypassed. This is useful when cache fragments
       # cannot be manually expired unless you know the exact key which is the
       # case when using memcached.
-      def cache_fragment_name(name = {}, options = nil)
-        skip_digest = options && options[:skip_digest]
-
+      #
+      # The digest will be generated using +virtual_path:+ if it is provided.
+      #
+      def cache_fragment_name(name = {}, skip_digest: nil, virtual_path: nil)
         if skip_digest
           name
         else
-          fragment_name_with_digest(name)
+          fragment_name_with_digest(name, virtual_path)
         end
       end
 
-    private
+      # Given a key (as described in ActionController::Caching::Fragments.expire_fragment),
+      # returns a key suitable for use in reading, writing, or expiring a
+      # cached fragment. All keys are prefixed with <tt>views/</tt> and uses
+      # ActiveSupport::Cache.expand_cache_key for the expansion.
+      def fragment_cache_key(key)
+        ActiveSupport::Cache.expand_cache_key(key.is_a?(Hash) ? url_for(key).split("://").last : key, :views)
+      end
 
-      def fragment_name_with_digest(name) #:nodoc:
-        if @virtual_path
-          names  = Array(name.is_a?(Hash) ? controller.url_for(name).split("://").last : name)
-          digest = Digestor.digest name: @virtual_path, finder: lookup_context, dependencies: view_cache_dependencies
+    private
 
-          [ *names, digest ]
+      def fragment_name_with_digest(name, virtual_path) #:nodoc:
+        virtual_path ||= @virtual_path
+        if virtual_path
+          name  = controller.url_for(name).split("://").last if name.is_a?(Hash)
+          digest = Digestor.digest name: virtual_path, finder: lookup_context, dependencies: view_cache_dependencies
+          [ name, digest ]
         else
           name
         end
diff --git a/actionview/lib/action_view/helpers/capture_helper.rb b/actionview/lib/action_view/helpers/capture_helper.rb
index 5a3223968f..93c7cba395 100644
--- a/actionview/lib/action_view/helpers/capture_helper.rb
+++ b/actionview/lib/action_view/helpers/capture_helper.rb
@@ -115,7 +115,7 @@ module ActionView
       #     <li><%= link_to 'Home', action: 'index' %></li>
       #   <% end %>
       #
-      #  And in other place:
+      #  And in another place:
       #
       #   <% content_for :navigation do %>
       #     <li><%= link_to 'Login', action: 'login' %></li>
@@ -195,7 +195,9 @@ module ActionView
       def with_output_buffer(buf = nil) #:nodoc:
         unless buf
           buf = ActionView::OutputBuffer.new
-          buf.force_encoding(output_buffer.encoding) if output_buffer
+          if output_buffer && output_buffer.respond_to?(:encoding)
+            buf.force_encoding(output_buffer.encoding)
+          end
         end
         self.output_buffer, old_buffer = buf, output_buffer
         yield
diff --git a/actionview/lib/action_view/helpers/controller_helper.rb b/actionview/lib/action_view/helpers/controller_helper.rb
index 74ef25f7c1..3569fba8c6 100644
--- a/actionview/lib/action_view/helpers/controller_helper.rb
+++ b/actionview/lib/action_view/helpers/controller_helper.rb
@@ -14,6 +14,7 @@ module ActionView
         if @_controller = controller
           @_request = controller.request if controller.respond_to?(:request)
           @_config  = controller.config.inheritable_copy if controller.respond_to?(:config)
+          @_default_form_builder = controller.default_form_builder if controller.respond_to?(:default_form_builder)
         end
       end
 
diff --git a/actionview/lib/action_view/helpers/date_helper.rb b/actionview/lib/action_view/helpers/date_helper.rb
index 4b4f0ae577..312e41ee48 100644
--- a/actionview/lib/action_view/helpers/date_helper.rb
+++ b/actionview/lib/action_view/helpers/date_helper.rb
@@ -68,6 +68,27 @@ module ActionView
       #   distance_of_time_in_words(from_time, to_time, include_seconds: true)                        # => about 6 years
       #   distance_of_time_in_words(to_time, from_time, include_seconds: true)                        # => about 6 years
       #   distance_of_time_in_words(Time.now, Time.now)                                               # => less than a minute
+      #
+      # With the <tt>scope</tt> option, you can define a custom scope for Rails
+      # to look up the translation.
+      #
+      # For example you can define the following in your locale (e.g. en.yml).
+      #
+      #   datetime:
+      #     distance_in_words:
+      #       short:
+      #         about_x_hours:
+      #           one: 'an hour'
+      #           other: '%{count} hours'
+      #
+      # See https://github.com/svenfuchs/rails-i18n/blob/master/rails/locale/en.yml
+      # for more examples.
+      #
+      # Which will then result in the following:
+      #
+      #   from_time = Time.now
+      #   distance_of_time_in_words(from_time, from_time + 50.minutes, scope: 'datetime.distance_in_words.short') # => "an hour"
+      #   distance_of_time_in_words(from_time, from_time + 3.hours, scope: 'datetime.distance_in_words.short')    # => "3 hours"
       def distance_of_time_in_words(from_time, to_time = 0, options = {})
         options = {
           scope: :'datetime.distance_in_words'
@@ -177,6 +198,8 @@ module ActionView
       #   and +:name+ (string). A format string would be something like "%{name} (%<number>02d)" for example.
       #   See <tt>Kernel.sprintf</tt> for documentation on format sequences.
       # * <tt>:date_separator</tt>    - Specifies a string to separate the date fields. Default is "" (i.e. nothing).
+      # * <tt>:time_separator</tt>    - Specifies a string to separate the time fields. Default is "" (i.e. nothing).
+      # * <tt>:datetime_separator</tt>- Specifies a string to separate the date and time fields. Default is "" (i.e. nothing).
       # * <tt>:start_year</tt>        - Set the start year for the year select. Default is <tt>Date.today.year - 5</tt> if
       #   you are creating new record. While editing existing record, <tt>:start_year</tt> defaults to
       #   the current selected year minus 5.
@@ -205,6 +228,7 @@ module ActionView
       #   or the given prompt string.
       # * <tt>:with_css_classes</tt>   - Set to true if you want assign different styles for 'select' tags. This option
       #   automatically set classes 'year', 'month', 'day', 'hour', 'minute' and 'second' for your 'select' tags.
+      # * <tt>:use_hidden</tt>         - Set to true if you only want to generate hidden input tags.
       #
       # If anything is passed in the +html_options+ hash it will be applied to every select tag in the set.
       #
@@ -462,7 +486,7 @@ module ActionView
       # The <tt>datetime</tt> can be either a +Time+ or +DateTime+ object or an integer.
       # Override the field name using the <tt>:field_name</tt> option, 'second' by default.
       #
-      #   my_time = Time.now + 16.minutes
+      #   my_time = Time.now + 16.seconds
       #
       #   # Generates a select field for seconds that defaults to the seconds for the time in my_time.
       #   select_second(my_time)
@@ -486,7 +510,7 @@ module ActionView
       # selected. The <tt>datetime</tt> can be either a +Time+ or +DateTime+ object or an integer.
       # Override the field name using the <tt>:field_name</tt> option, 'minute' by default.
       #
-      #   my_time = Time.now + 6.hours
+      #   my_time = Time.now + 10.minutes
       #
       #   # Generates a select field for minutes that defaults to the minutes for the time in my_time.
       #   select_minute(my_time)
@@ -658,7 +682,7 @@ module ActionView
         content  = args.first || I18n.l(date_or_time, :format => format)
         datetime = date_or_time.acts_like?(:time) ? date_or_time.xmlschema : date_or_time.iso8601
 
-        content_tag(:time, content, options.reverse_merge(:datetime => datetime), &block)
+        content_tag("time".freeze, content, options.reverse_merge(:datetime => datetime), &block)
       end
     end
 
@@ -786,7 +810,7 @@ module ActionView
           1.upto(12) do |month_number|
             options = { :value => month_number }
             options[:selected] = "selected" if month == month_number
-            month_options << content_tag(:option, month_name(month_number), options) + "\n"
+            month_options << content_tag("option".freeze, month_name(month_number), options) + "\n"
           end
           build_select(:month, month_options.join)
         end
@@ -948,7 +972,7 @@ module ActionView
             tag_options[:selected] = "selected" if selected == i
             text = options[:use_two_digit_numbers] ? sprintf("%02d", i) : value
             text = options[:ampm] ? AMPM_TRANSLATION[i] : text
-            select_options << content_tag(:option, text, tag_options)
+            select_options << content_tag("option".freeze, text, tag_options)
           end
 
           (select_options.join("\n") + "\n").html_safe
@@ -968,11 +992,11 @@ module ActionView
           select_options[:class] = [select_options[:class], type].compact.join(' ') if @options[:with_css_classes]
 
           select_html = "\n"
-          select_html << content_tag(:option, '', :value => '') + "\n" if @options[:include_blank]
+          select_html << content_tag("option".freeze, '', :value => '') + "\n" if @options[:include_blank]
           select_html << prompt_option_tag(type, @options[:prompt]) + "\n" if @options[:prompt]
           select_html << select_options_as_html
 
-          (content_tag(:select, select_html.html_safe, select_options) + "\n").html_safe
+          (content_tag("select".freeze, select_html.html_safe, select_options) + "\n").html_safe
         end
 
         # Builds a prompt option tag with supplied options or from default options.
@@ -989,7 +1013,7 @@ module ActionView
               I18n.translate(:"datetime.prompts.#{type}", :locale => @options[:locale])
           end
 
-          prompt ? content_tag(:option, prompt, :value => '') : ''
+          prompt ? content_tag("option".freeze, prompt, :value => '') : ''
         end
 
         # Builds hidden input tag for date part and value.
diff --git a/actionview/lib/action_view/helpers/debug_helper.rb b/actionview/lib/action_view/helpers/debug_helper.rb
index ba47eee9ba..e9dccbad1c 100644
--- a/actionview/lib/action_view/helpers/debug_helper.rb
+++ b/actionview/lib/action_view/helpers/debug_helper.rb
@@ -26,7 +26,7 @@ module ActionView
         Marshal::dump(object)
         object = ERB::Util.html_escape(object.to_yaml)
         content_tag(:pre, object, :class => "debug_dump")
-      rescue Exception  # errors from Marshal or YAML
+      rescue # errors from Marshal or YAML
         # Object couldn't be dumped, perhaps because of singleton methods -- this is the fallback
         content_tag(:code, object.inspect, :class => "debug_dump")
       end
diff --git a/actionview/lib/action_view/helpers/form_helper.rb b/actionview/lib/action_view/helpers/form_helper.rb
index 8d78ba13d5..2a367b85af 100644
--- a/actionview/lib/action_view/helpers/form_helper.rb
+++ b/actionview/lib/action_view/helpers/form_helper.rb
@@ -4,6 +4,7 @@ require 'action_view/helpers/tag_helper'
 require 'action_view/helpers/form_tag_helper'
 require 'action_view/helpers/active_model_helper'
 require 'action_view/model_naming'
+require 'action_view/record_identifier'
 require 'active_support/core_ext/module/attribute_accessors'
 require 'active_support/core_ext/hash/slice'
 require 'active_support/core_ext/string/output_safety'
@@ -66,9 +67,10 @@ module ActionView
     #
     # In particular, thanks to the conventions followed in the generated field names, the
     # controller gets a nested hash <tt>params[:person]</tt> with the person attributes
-    # set in the form. That hash is ready to be passed to <tt>Person.create</tt>:
+    # set in the form. That hash is ready to be passed to <tt>Person.new</tt>:
     #
-    #   if @person = Person.create(params[:person])
+    #   @person = Person.new(params[:person])
+    #   if @person.save
     #     # success
     #   else
     #     # error handling
@@ -110,6 +112,9 @@ module ActionView
       include FormTagHelper
       include UrlHelper
       include ModelNaming
+      include RecordIdentifier
+
+      attr_internal :default_form_builder
 
       # Creates a form that allows the user to create or update the attributes
       # of a specific model object.
@@ -138,6 +143,7 @@ module ActionView
       # will get expanded to
       #
       #   <%= text_field :person, :first_name %>
+      #
       # which results in an HTML <tt><input></tt> tag whose +name+ attribute is
       # <tt>person[first_name]</tt>. This means that when the form is submitted,
       # the value entered by the user will be available in the controller as
@@ -843,8 +849,8 @@ module ActionView
       #   file_field(:user, :avatar)
       #   # => <input type="file" id="user_avatar" name="user[avatar]" />
       #
-      #   file_field(:post, :image, :multiple => true)
-      #   # => <input type="file" id="post_image" name="post[image]" multiple="true" />
+      #   file_field(:post, :image, multiple: true)
+      #   # => <input type="file" id="post_image" name="post[image][]" multiple="multiple" />
       #
       #   file_field(:post, :attached, accept: 'text/html')
       #   # => <input accept="text/html" type="file" id="post_attached" name="post[attached]" />
@@ -1032,7 +1038,7 @@ module ActionView
       #   date_field("user", "born_on")
       #   # => <input id="user_born_on" name="user[born_on]" type="date" />
       #
-      # The default value is generated by trying to call "to_date"
+      # The default value is generated by trying to call +strftime+ with "%Y-%m-%d"
       # on the object's value, which makes it behave as expected for instances
       # of DateTime and ActiveSupport::TimeWithZone. You can still override that
       # by passing the "value" option explicitly, e.g.
@@ -1224,12 +1230,12 @@ module ActionView
             object_name = model_name_from_record_or_class(object).param_key
           end
 
-          builder = options[:builder] || default_form_builder
+          builder = options[:builder] || default_form_builder_class
           builder.new(object_name, object, self, options)
         end
 
-        def default_form_builder
-          builder = ActionView::Base.default_form_builder
+        def default_form_builder_class
+          builder = default_form_builder || ActionView::Base.default_form_builder
           builder.respond_to?(:constantize) ? builder.constantize : builder
         end
     end
@@ -1244,7 +1250,7 @@ module ActionView
     #     Admin: <%= person_form.check_box :admin %>
     #   <% end %>
     #
-    # In the above block, the a +FormBuilder+ object is yielded as the
+    # In the above block, a +FormBuilder+ object is yielded as the
     # +person_form+ variable. This allows you to generate the +text_field+
     # and +check_box+ fields by specifying their eponymous methods, which
     # modify the underlying template and associates the +@person+ model object
@@ -1265,6 +1271,7 @@ module ActionView
     #         )
     #       )
     #     end
+    #   end
     #
     # The above code creates a new method +div_radio_button+ which wraps a div
     # around the new radio button. Note that when options are passed in, you
@@ -1610,7 +1617,14 @@ module ActionView
           @auto_index
         end
 
-        record_name = index ? "#{object_name}[#{index}][#{record_name}]" : "#{object_name}[#{record_name}]"
+        record_name = if index
+                        "#{object_name}[#{index}][#{record_name}]"
+                      elsif record_name.to_s.end_with?('[]')
+                        record_name = record_name.to_s.sub(/(.*)\[\]$/, "[\\1][#{record_object.id}]")
+                        "#{object_name}#{record_name}"
+                      else
+                        "#{object_name}[#{record_name}]"
+                      end
         fields_options[:child_index] = index
 
         @template.fields_for(record_name, record_object, fields_options, &block)
@@ -1624,7 +1638,7 @@ module ActionView
       # target labels for radio_button tags (where the value is used in the ID of the input tag).
       #
       # ==== Examples
-      #   label(:post, :title)
+      #   label(:title)
       #   # => <label for="post_title">Title</label>
       #
       # You can localize your labels based on model and attribute names.
@@ -1637,7 +1651,7 @@ module ActionView
       #
       # Which then will result in
       #
-      #   label(:post, :body)
+      #   label(:body)
       #   # => <label for="post_body">Write your entire text here</label>
       #
       # Localization can also be based purely on the translation of the attribute-name
@@ -1648,21 +1662,22 @@ module ActionView
       #       post:
       #         cost: "Total cost"
       #
-      #   label(:post, :cost)
+      #   label(:cost)
       #   # => <label for="post_cost">Total cost</label>
       #
-      #   label(:post, :title, "A short title")
+      #   label(:title, "A short title")
       #   # => <label for="post_title">A short title</label>
       #
-      #   label(:post, :title, "A short title", class: "title_label")
+      #   label(:title, "A short title", class: "title_label")
       #   # => <label for="post_title" class="title_label">A short title</label>
       #
-      #   label(:post, :privacy, "Public Post", value: "public")
+      #   label(:privacy, "Public Post", value: "public")
       #   # => <label for="post_privacy_public">Public Post</label>
       #
-      #   label(:post, :terms) do
+      #   label(:terms) do
       #     'Accept <a href="/terms">Terms</a>.'.html_safe
       #   end
+      #   # => <label for="post_terms">Accept <a href="/terms">Terms</a>.</label>
       def label(method, text = nil, options = {}, &block)
         @template.label(@object_name, method, text, objectify_options(options), &block)
       end
@@ -1711,16 +1726,17 @@ module ActionView
       # hashes instead of arrays.
       #
       #   # Let's say that @post.validated? is 1:
-      #   check_box("post", "validated")
+      #   check_box("validated")
       #   # => <input name="post[validated]" type="hidden" value="0" />
       #   #    <input checked="checked" type="checkbox" id="post_validated" name="post[validated]" value="1" />
       #
       #   # Let's say that @puppy.gooddog is "no":
-      #   check_box("puppy", "gooddog", {}, "yes", "no")
+      #   check_box("gooddog", {}, "yes", "no")
       #   # => <input name="puppy[gooddog]" type="hidden" value="no" />
       #   #    <input type="checkbox" id="puppy_gooddog" name="puppy[gooddog]" value="yes" />
       #
-      #   check_box("eula", "accepted", { class: 'eula_check' }, "yes", "no")
+      #   # Let's say that @eula.accepted is "no":
+      #   check_box("accepted", { class: 'eula_check' }, "yes", "no")
       #   # => <input name="eula[accepted]" type="hidden" value="no" />
       #   #    <input type="checkbox" class="eula_check" id="eula_accepted" name="eula[accepted]" value="yes" />
       def check_box(method, options = {}, checked_value = "1", unchecked_value = "0")
@@ -1735,13 +1751,14 @@ module ActionView
       # +options+ hash. You may pass HTML options there as well.
       #
       #   # Let's say that @post.category returns "rails":
-      #   radio_button("post", "category", "rails")
-      #   radio_button("post", "category", "java")
+      #   radio_button("category", "rails")
+      #   radio_button("category", "java")
       #   # => <input type="radio" id="post_category_rails" name="post[category]" value="rails" checked="checked" />
       #   #    <input type="radio" id="post_category_java" name="post[category]" value="java" />
       #
-      #   radio_button("user", "receive_newsletter", "yes")
-      #   radio_button("user", "receive_newsletter", "no")
+      #   # Let's say that @user.category returns "no":
+      #   radio_button("receive_newsletter", "yes")
+      #   radio_button("receive_newsletter", "no")
       #   # => <input type="radio" id="user_receive_newsletter_yes" name="user[receive_newsletter]" value="yes" />
       #   #    <input type="radio" id="user_receive_newsletter_no" name="user[receive_newsletter]" value="no" checked="checked" />
       def radio_button(method, tag_value, options = {})
@@ -1754,14 +1771,17 @@ module ActionView
       # shown.
       #
       # ==== Examples
-      #   hidden_field(:signup, :pass_confirm)
-      #   # => <input type="hidden" id="signup_pass_confirm" name="signup[pass_confirm]" value="#{@signup.pass_confirm}" />
+      #   # Let's say that @signup.pass_confirm returns true:
+      #   hidden_field(:pass_confirm)
+      #   # => <input type="hidden" id="signup_pass_confirm" name="signup[pass_confirm]" value="true" />
       #
-      #   hidden_field(:post, :tag_list)
-      #   # => <input type="hidden" id="post_tag_list" name="post[tag_list]" value="#{@post.tag_list}" />
+      #   # Let's say that @post.tag_list returns "blog, ruby":
+      #   hidden_field(:tag_list)
+      #   # => <input type="hidden" id="post_tag_list" name="post[tag_list]" value="blog, ruby" />
       #
-      #   hidden_field(:user, :token)
-      #   # => <input type="hidden" id="user_token" name="user[token]" value="#{@user.token}" />
+      #   # Let's say that @user.token returns "abcde":
+      #   hidden_field(:token)
+      #   # => <input type="hidden" id="user_token" name="user[token]" value="abcde" />
       #
       def hidden_field(method, options = {})
         @emitted_hidden_id = true if method == :id
@@ -1782,19 +1802,24 @@ module ActionView
       # * <tt>:accept</tt> - If set to one or multiple mime-types, the user will be suggested a filter when choosing a file. You still need to set up model validations.
       #
       # ==== Examples
-      #   file_field(:user, :avatar)
+      #   # Let's say that @user has avatar:
+      #   file_field(:avatar)
       #   # => <input type="file" id="user_avatar" name="user[avatar]" />
       #
-      #   file_field(:post, :image, :multiple => true)
-      #   # => <input type="file" id="post_image" name="post[image]" multiple="true" />
+      #   # Let's say that @post has image:
+      #   file_field(:image, :multiple => true)
+      #   # => <input type="file" id="post_image" name="post[image][]" multiple="multiple" />
       #
-      #   file_field(:post, :attached, accept: 'text/html')
+      #   # Let's say that @post has attached:
+      #   file_field(:attached, accept: 'text/html')
       #   # => <input accept="text/html" type="file" id="post_attached" name="post[attached]" />
       #
-      #   file_field(:post, :image, accept: 'image/png,image/gif,image/jpeg')
+      #   # Let's say that @post has image:
+      #   file_field(:image, accept: 'image/png,image/gif,image/jpeg')
       #   # => <input type="file" id="post_image" name="post[image]" accept="image/png,image/gif,image/jpeg" />
       #
-      #   file_field(:attachment, :file, class: 'file_input')
+      #   # Let's say that @attachment has file:
+      #   file_field(:file, class: 'file_input')
       #   # => <input type="file" id="attachment_file" name="attachment[file]" class="file_input" />
       def file_field(method, options = {})
         self.multipart = true
@@ -1862,7 +1887,7 @@ module ActionView
       #           create: "Add %{model}"
       #
       # ==== Examples
-      #   button("Create a post")
+      #   button("Create post")
       #   # => <button name='button' type='submit'>Create post</button>
       #
       #   button do
@@ -1923,7 +1948,11 @@ module ActionView
             explicit_child_index = options[:child_index]
             output = ActiveSupport::SafeBuffer.new
             association.each do |child|
-              options[:child_index] = nested_child_index(name) unless explicit_child_index
+              if explicit_child_index
+                options[:child_index] = explicit_child_index.call if explicit_child_index.respond_to?(:call)
+              else
+                options[:child_index] = nested_child_index(name)
+              end
               output << fields_for_nested_model("#{name}[#{options[:child_index]}]", child, options, block)
             end
             output
diff --git a/actionview/lib/action_view/helpers/form_options_helper.rb b/actionview/lib/action_view/helpers/form_options_helper.rb
index bbfbf482a4..430051379d 100644
--- a/actionview/lib/action_view/helpers/form_options_helper.rb
+++ b/actionview/lib/action_view/helpers/form_options_helper.rb
@@ -18,10 +18,10 @@ module ActionView
     #
     #   could become:
     #
-    #     <select name="post[category]">
-    #       <option></option>
-    #       <option>joke</option>
-    #       <option>poem</option>
+    #     <select name="post[category]" id="post_category">
+    #       <option value=""></option>
+    #       <option value="joke">joke</option>
+    #       <option value="poem">poem</option>
     #     </select>
     #
     #   Another common case is a select tag for a <tt>belongs_to</tt>-associated object.
@@ -32,11 +32,11 @@ module ActionView
     #
     #   could become:
     #
-    #     <select name="post[person_id]">
+    #     <select name="post[person_id]" id="post_person_id">
     #       <option value="">None</option>
     #       <option value="1">David</option>
-    #       <option value="2" selected="selected">Sam</option>
-    #       <option value="3">Tobias</option>
+    #       <option value="2" selected="selected">Eileen</option>
+    #       <option value="3">Rafael</option>
     #     </select>
     #
     # * <tt>:prompt</tt> - set to true or a prompt string. When the select element doesn't have a value yet, this prepends an option with a generic prompt -- "Please select" -- or the given prompt string.
@@ -45,11 +45,11 @@ module ActionView
     #
     #   could become:
     #
-    #     <select name="post[person_id]">
+    #     <select name="post[person_id]" id="post_person_id">
     #       <option value="">Select Person</option>
     #       <option value="1">David</option>
-    #       <option value="2">Sam</option>
-    #       <option value="3">Tobias</option>
+    #       <option value="2">Eileen</option>
+    #       <option value="3">Rafael</option>
     #     </select>
     #
     # * <tt>:index</tt> - like the other form helpers, +select+ can accept an <tt>:index</tt> option to manually set the ID used in the resulting output. Unlike other helpers, +select+ expects this
@@ -71,19 +71,19 @@ module ActionView
     #
     #   could become:
     #
-    #     <select name="post[category]">
-    #       <option></option>
-    #       <option>joke</option>
-    #       <option>poem</option>
-    #       <option disabled="disabled">restricted</option>
+    #     <select name="post[category]" id="post_category">
+    #       <option value=""></option>
+    #       <option value="joke">joke</option>
+    #       <option value="poem">poem</option>
+    #       <option disabled="disabled" value="restricted">restricted</option>
     #     </select>
     #
     #   When used with the <tt>collection_select</tt> helper, <tt>:disabled</tt> can also be a Proc that identifies those options that should be disabled.
     #
-    #     collection_select(:post, :category_id, Category.all, :id, :name, {disabled: lambda{|category| category.archived? }})
+    #     collection_select(:post, :category_id, Category.all, :id, :name, {disabled: -> (category) { category.archived? }})
     #
     #   If the categories "2008 stuff" and "Christmas" return true when the method <tt>archived?</tt> is called, this would return:
-    #     <select name="post[category_id]">
+    #     <select name="post[category_id]" id="post_category_id">
     #       <option value="1" disabled="disabled">2008 stuff</option>
     #       <option value="2" disabled="disabled">Christmas</option>
     #       <option value="3">Jokes</option>
@@ -109,11 +109,11 @@ module ActionView
       #
       # would become:
       #
-      #   <select name="post[person_id]">
+      #   <select name="post[person_id]" id="post_person_id">
       #     <option value=""></option>
       #     <option value="1" selected="selected">David</option>
-      #     <option value="2">Sam</option>
-      #     <option value="3">Tobias</option>
+      #     <option value="2">Eileen</option>
+      #     <option value="3">Rafael</option>
       #   </select>
       #
       # assuming the associated person has ID 1.
@@ -192,7 +192,7 @@ module ActionView
       #   collection_select(:post, :author_id, Author.all, :id, :name_with_initial, prompt: true)
       #
       # If <tt>@post.author_id</tt> is already <tt>1</tt>, this would return:
-      #   <select name="post[author_id]">
+      #   <select name="post[author_id]" id="post_author_id">
       #     <option value="">Please select</option>
       #     <option value="1" selected="selected">D. Heinemeier Hansson</option>
       #     <option value="2">D. Thomas</option>
@@ -243,7 +243,7 @@ module ActionView
       #
       # Possible output:
       #
-      #   <select name="city[country_id]">
+      #   <select name="city[country_id]" id="city_country_id">
       #     <optgroup label="Africa">
       #       <option value="1">South Africa</option>
       #       <option value="3">Somalia</option>
@@ -302,17 +302,17 @@ module ActionView
       #   # => <option value="DKK">Kroner</option>
       #
       #   options_for_select([ "VISA", "MasterCard" ], "MasterCard")
-      #   # => <option>VISA</option>
-      #   # => <option selected="selected">MasterCard</option>
+      #   # => <option value="VISA">VISA</option>
+      #   # => <option selected="selected" value="MasterCard">MasterCard</option>
       #
       #   options_for_select({ "Basic" => "$20", "Plus" => "$40" }, "$40")
       #   # => <option value="$20">Basic</option>
       #   # => <option value="$40" selected="selected">Plus</option>
       #
       #   options_for_select([ "VISA", "MasterCard", "Discover" ], ["VISA", "Discover"])
-      #   # => <option selected="selected">VISA</option>
-      #   # => <option>MasterCard</option>
-      #   # => <option selected="selected">Discover</option>
+      #   # => <option selected="selected" value="VISA">VISA</option>
+      #   # => <option value="MasterCard">MasterCard</option>
+      #   # => <option selected="selected" value="Discover">Discover</option>
       #
       # You can optionally provide HTML attributes as the last element of the array.
       #
@@ -410,7 +410,7 @@ module ActionView
       # * +collection+ - An array of objects representing the <tt><optgroup></tt> tags.
       # * +group_method+ - The name of a method which, when called on a member of +collection+, returns an
       #   array of child objects representing the <tt><option></tt> tags.
-      # * group_label_method+ - The name of a method which, when called on a member of +collection+, returns a
+      # * +group_label_method+ - The name of a method which, when called on a member of +collection+, returns a
       #   string to be used as the +label+ attribute for its <tt><optgroup></tt> tag.
       # * +option_key_method+ - The name of a method which, when called on a child object of a member of
       #   +collection+, returns a value to be used as the +value+ attribute for its <tt><option></tt> tag.
@@ -456,7 +456,7 @@ module ActionView
           option_tags = options_from_collection_for_select(
             group.send(group_method), option_key_method, option_value_method, selected_key)
 
-          content_tag(:optgroup, option_tags, label: group.send(group_label_method))
+          content_tag("optgroup".freeze, option_tags, label: group.send(group_label_method))
         end.join.html_safe
       end
 
@@ -528,7 +528,7 @@ module ActionView
         body = "".html_safe
 
         if prompt
-          body.safe_concat content_tag(:option, prompt_text(prompt), value: "")
+          body.safe_concat content_tag("option".freeze, prompt_text(prompt), value: "")
         end
 
         grouped_options.each do |container|
@@ -541,14 +541,14 @@ module ActionView
           end
 
           html_attributes = { label: label }.merge!(html_attributes)
-          body.safe_concat content_tag(:optgroup, options_for_select(container, selected_key), html_attributes)
+          body.safe_concat content_tag("optgroup".freeze, options_for_select(container, selected_key), html_attributes)
         end
 
         body
       end
 
       # Returns a string of option tags for pretty much any time zone in the
-      # world. Supply a ActiveSupport::TimeZone name as +selected+ to have it
+      # world. Supply an ActiveSupport::TimeZone name as +selected+ to have it
       # marked as the selected option tag. You can also supply an array of
       # ActiveSupport::TimeZone objects as +priority_zones+, so that they will
       # be listed above the rest of the (long) list. (You can use
@@ -556,7 +556,7 @@ module ActionView
       # of the US time zones, or a Regexp to select the zones of your choice)
       #
       # The +selected+ parameter must be either +nil+, or a string that names
-      # a ActiveSupport::TimeZone.
+      # an ActiveSupport::TimeZone.
       #
       # By default, +model+ is the ActiveSupport::TimeZone constant (which can
       # be obtained in Active Record as a value object). The only requirement
@@ -577,7 +577,7 @@ module ActionView
           end
 
           zone_options.safe_concat options_for_select(convert_zones[priority_zones], selected)
-          zone_options.safe_concat content_tag(:option, '-------------', value: '', disabled: true)
+          zone_options.safe_concat content_tag("option".freeze, '-------------', value: '', disabled: true)
           zone_options.safe_concat "\n"
 
           zones = zones - priority_zones
@@ -644,6 +644,24 @@ module ActionView
       #   collection_radio_buttons(:post, :author_id, Author.all, :id, :name_with_initial) do |b|
       #      b.label(:"data-value" => b.value) { b.radio_button + b.text }
       #   end
+      #
+      # ==== Gotcha
+      #
+      # The HTML specification says when nothing is select on a collection of radio buttons
+      # web browsers do not send any value to server.
+      # Unfortunately this introduces a gotcha:
+      # if a +User+ model has a +category_id+ field, and in the form none category is selected no +category_id+ parameter is sent. So,
+      # any strong parameters idiom like
+      #
+      #   params.require(:user).permit(...)
+      #
+      # will raise an error since no +{user: ...}+ will be present.
+      #
+      # To prevent this the helper generates an auxiliary hidden field before
+      # every collection of radio buttons. The hidden field has the same name as collection radio button and blank value.
+      #
+      # In case if you don't want the helper to generate this hidden field you can specify
+      # <tt>include_hidden: false</tt> option.
       def collection_radio_buttons(object, method, collection, value_method, text_method, options = {}, html_options = {}, &block)
         Tags::CollectionRadioButtons.new(object, method, self, collection, value_method, text_method, options, html_options).render(&block)
       end
@@ -707,6 +725,27 @@ module ActionView
       #   collection_check_boxes(:post, :author_ids, Author.all, :id, :name_with_initial) do |b|
       #      b.label(:"data-value" => b.value) { b.check_box + b.text }
       #   end
+      #
+      # ==== Gotcha
+      #
+      # When no selection is made for a collection of checkboxes most
+      # web browsers will not send any value.
+      #
+      # For example, if we have a +User+ model with +category_ids+ field and we
+      # have the following code in our update action:
+      #
+      #   @user.update(params[:user])
+      #
+      # If no +category_ids+ are selected then we can safely assume this field
+      # will not be updated.
+      #
+      # This is possible thanks to a hidden field generated by the helper method
+      # for every collection of checkboxes.
+      # This hidden field is given the same field name as the checkboxes with a
+      # blank value.
+      #
+      # In the rare case you don't want this hidden field, you can pass the
+      # <tt>include_hidden: false</tt> option to the helper method.
       def collection_check_boxes(object, method, collection, value_method, text_method, options = {}, html_options = {}, &block)
         Tags::CollectionCheckBoxes.new(object, method, self, collection, value_method, text_method, options, html_options).render(&block)
       end
diff --git a/actionview/lib/action_view/helpers/form_tag_helper.rb b/actionview/lib/action_view/helpers/form_tag_helper.rb
index 93c04fbec6..0191064326 100644
--- a/actionview/lib/action_view/helpers/form_tag_helper.rb
+++ b/actionview/lib/action_view/helpers/form_tag_helper.rb
@@ -20,7 +20,7 @@ module ActionView
       mattr_accessor :embed_authenticity_token_in_remote_forms
       self.embed_authenticity_token_in_remote_forms = false
 
-      # Starts a form tag that points the action to an url configured with <tt>url_for_options</tt> just like
+      # Starts a form tag that points the action to a url configured with <tt>url_for_options</tt> just like
       # ActionController::Base#url_for. The method for the form defaults to POST.
       #
       # ==== Options
@@ -80,18 +80,17 @@ module ActionView
       # associated records. <tt>option_tags</tt> is a string containing the option tags for the select box.
       #
       # ==== Options
-      # * <tt>:multiple</tt> - If set to true the selection will allow multiple choices.
+      # * <tt>:multiple</tt> - If set to true, the selection will allow multiple choices.
       # * <tt>:disabled</tt> - If set to true, the user will not be able to use this input.
       # * <tt>:include_blank</tt> - If set to true, an empty option will be created. If set to a string, the string will be used as the option's content and the value will be empty.
       # * <tt>:prompt</tt> - Create a prompt option with blank value and the text asking user to select something.
-      # * <tt>:selected</tt> - Provide a default selected value. It should be of the exact type as the provided options.
       # * Any other key creates standard HTML attributes for the tag.
       #
       # ==== Examples
       #   select_tag "people", options_from_collection_for_select(@people, "id", "name")
       #   # <select id="people" name="people"><option value="1">David</option></select>
       #
-      #   select_tag "people", options_from_collection_for_select(@people, "id", "name"), selected: ["1", "David"]
+      #   select_tag "people", options_from_collection_for_select(@people, "id", "name", "1")
       #   # <select id="people" name="people"><option value="1" selected="selected">David</option></select>
       #
       #   select_tag "people", "<option>David</option>".html_safe
@@ -141,15 +140,15 @@ module ActionView
           end
 
           if include_blank
-            option_tags = content_tag(:option, include_blank, value: '').safe_concat(option_tags)
+            option_tags = content_tag("option".freeze, include_blank, value: '').safe_concat(option_tags)
           end
         end
 
         if prompt = options.delete(:prompt)
-          option_tags = content_tag(:option, prompt, value: '').safe_concat(option_tags)
+          option_tags = content_tag("option".freeze, prompt, value: '').safe_concat(option_tags)
         end
 
-        content_tag :select, option_tags, { "name" => html_name, "id" => sanitize_to_id(name) }.update(options.stringify_keys)
+        content_tag "select".freeze, option_tags, { "name" => html_name, "id" => sanitize_to_id(name) }.update(options.stringify_keys)
       end
 
       # Creates a standard text field; use these text fields to input smaller chunks of text like a username
@@ -415,42 +414,57 @@ module ActionView
       #   the form is processed normally, otherwise no action is taken.
       # * <tt>:disable_with</tt> - Value of this parameter will be used as the value for a
       #   disabled version of the submit button when the form is submitted. This feature is
-      #   provided by the unobtrusive JavaScript driver.
+      #   provided by the unobtrusive JavaScript driver. To disable this feature for a single submit tag
+      #   pass <tt>:data => { disable_with: false }</tt> Defaults to value attribute.
       #
       # ==== Examples
       #   submit_tag
-      #   # => <input name="commit" type="submit" value="Save changes" />
+      #   # => <input name="commit" data-disable-with="Save changes" type="submit" value="Save changes" />
       #
       #   submit_tag "Edit this article"
-      #   # => <input name="commit" type="submit" value="Edit this article" />
+      #   # => <input name="commit" data-disable-with="Edit this article" type="submit" value="Edit this article" />
       #
       #   submit_tag "Save edits", disabled: true
-      #   # => <input disabled="disabled" name="commit" type="submit" value="Save edits" />
+      #   # => <input disabled="disabled" name="commit" data-disable-with="Save edits" type="submit" value="Save edits" />
       #
-      #   submit_tag "Complete sale", data: { disable_with: "Please wait..." }
-      #   # => <input name="commit" data-disable-with="Please wait..." type="submit" value="Complete sale" />
+      #   submit_tag "Complete sale", data: { disable_with: "Submitting..." }
+      #   # => <input name="commit" data-disable-with="Submitting..." type="submit" value="Complete sale" />
       #
       #   submit_tag nil, class: "form_submit"
       #   # => <input class="form_submit" name="commit" type="submit" />
       #
       #   submit_tag "Edit", class: "edit_button"
-      #   # => <input class="edit_button" name="commit" type="submit" value="Edit" />
+      #   # => <input class="edit_button" data-disable-with="Edit" name="commit" type="submit" value="Edit" />
       #
       #   submit_tag "Save", data: { confirm: "Are you sure?" }
-      #   # => <input name='commit' type='submit' value='Save' data-confirm="Are you sure?" />
+      #   # => <input name='commit' type='submit' value='Save' data-disable-with="Save" data-confirm="Are you sure?" />
       #
       def submit_tag(value = "Save changes", options = {})
         options = options.stringify_keys
+        tag_options = { "type" => "submit", "name" => "commit", "value" => value }.update(options)
+
+        if ActionView::Base.automatically_disable_submit_tag
+          unless tag_options["data-disable-with"] == false || (tag_options["data"] && tag_options["data"][:disable_with] == false)
+            disable_with_text = tag_options["data-disable-with"]
+            disable_with_text ||= tag_options["data"][:disable_with] if tag_options["data"]
+            disable_with_text ||= value.clone
+            tag_options.deep_merge!("data" => { "disable_with" => disable_with_text })
+          else
+            tag_options["data"].delete(:disable_with) if tag_options["data"]
+          end
+          tag_options.delete("data-disable-with")
+        end
 
-        tag :input, { "type" => "submit", "name" => "commit", "value" => value }.update(options)
+        tag :input, tag_options
       end
 
       # Creates a button element that defines a <tt>submit</tt> button,
       # <tt>reset</tt>button or a generic button which can be used in
       # JavaScript, for example. You can use the button tag as a regular
       # submit tag but it isn't supported in legacy browsers. However,
-      # the button tag allows richer labels such as images and emphasis,
-      # so this helper will also accept a block.
+      # the button tag does allow for richer labels such as images and emphasis,
+      # so this helper will also accept a block. By default, it will create
+      # a button tag with type `submit`, if type is not given.
       #
       # ==== Options
       # * <tt>:data</tt> - This option can be used to add custom data attributes.
@@ -473,6 +487,15 @@ module ActionView
       #   button_tag
       #   # => <button name="button" type="submit">Button</button>
       #
+      #   button_tag 'Reset', type: 'reset'
+      #   # => <button name="button" type="reset">Reset</button>
+      #
+      #   button_tag 'Button', type: 'button'
+      #   # => <button name="button" type="button">Button</button>
+      #
+      #   button_tag 'Reset', type: 'reset', disabled: true
+      #   # => <button name="button" type="reset" disabled="disabled">Reset</button>
+      #
       #   button_tag(type: 'button') do
       #     content_tag(:strong, 'Ask me!')
       #   end
@@ -480,6 +503,9 @@ module ActionView
       #   #     <strong>Ask me!</strong>
       #   #    </button>
       #
+      #   button_tag "Save", data: { confirm: "Are you sure?" }
+      #   # => <button name="button" type="submit" data-confirm="Are you sure?">Save</button>
+      #
       #   button_tag "Checkout", data: { disable_with: "Please wait..." }
       #   # => <button data-disable-with="Please wait..." name="button" type="submit">Checkout</button>
       #
@@ -556,7 +582,7 @@ module ActionView
       #   # => <fieldset class="format"><p><input id="name" name="name" type="text" /></p></fieldset>
       def field_set_tag(legend = nil, options = nil, &block)
         output = tag(:fieldset, options, true)
-        output.safe_concat(content_tag(:legend, legend)) unless legend.blank?
+        output.safe_concat(content_tag("legend".freeze, legend)) unless legend.blank?
         output.concat(capture(&block)) if block_given?
         output.safe_concat("</fieldset>")
       end
@@ -777,10 +803,10 @@ module ActionView
       #   # => <input id="quantity" name="quantity" min="1" max="9" type="number" />
       #
       #   number_field_tag 'quantity', nil, min: 1, max: 10
-      #   # => <input id="quantity" name="quantity" min="1" max="9" type="number" />
+      #   # => <input id="quantity" name="quantity" min="1" max="10" type="number" />
       #
       #   number_field_tag 'quantity', nil, min: 1, max: 10, step: 2
-      #   # => <input id="quantity" name="quantity" min="1" max="9" step="2" type="number" />
+      #   # => <input id="quantity" name="quantity" min="1" max="10" step="2" type="number" />
       #
       #   number_field_tag 'quantity', '1', class: 'special_input', disabled: true
       #   # => <input disabled="disabled" class="special_input" id="quantity" name="quantity" type="number" value="1" />
diff --git a/actionview/lib/action_view/helpers/javascript_helper.rb b/actionview/lib/action_view/helpers/javascript_helper.rb
index 629c447f3f..ed7e882c94 100644
--- a/actionview/lib/action_view/helpers/javascript_helper.rb
+++ b/actionview/lib/action_view/helpers/javascript_helper.rb
@@ -21,7 +21,7 @@ module ActionView
       # Also available through the alias j(). This is particularly helpful in JavaScript
       # responses, like:
       #
-      #   $('some_element').replaceWith('<%=j render 'some/element_template' %>');
+      #   $('some_element').replaceWith('<%= j render 'some/element_template' %>');
       def escape_javascript(javascript)
         if javascript
           result = javascript.gsub(/(\\|<\/|\r\n|\342\200\250|\342\200\251|[\n\r"'])/u) {|match| JS_ESCAPE_MAP[match] }
@@ -47,8 +47,8 @@ module ActionView
       # tag.
       #
       #   javascript_tag "alert('All is good')", defer: 'defer'
-      # 
-      # Returns: 
+      #
+      # Returns:
       #   <script defer="defer">
       #   //<![CDATA[
       #   alert('All is good')
@@ -70,7 +70,7 @@ module ActionView
             content_or_options_with_block
           end
 
-        content_tag(:script, javascript_cdata_section(content), html_options)
+        content_tag("script".freeze, javascript_cdata_section(content), html_options)
       end
 
       def javascript_cdata_section(content) #:nodoc:
diff --git a/actionview/lib/action_view/helpers/number_helper.rb b/actionview/lib/action_view/helpers/number_helper.rb
index f66dbfe7d3..d7182d1fac 100644
--- a/actionview/lib/action_view/helpers/number_helper.rb
+++ b/actionview/lib/action_view/helpers/number_helper.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 require 'active_support/core_ext/hash/keys'
 require 'active_support/core_ext/string/output_safety'
 require 'active_support/number_helper'
@@ -117,8 +115,8 @@ module ActionView
       #   (defaults to current locale).
       # * <tt>:precision</tt> - Sets the precision of the number
       #   (defaults to 3).
-      # * <tt>:significant</tt> - If +true+, precision will be the #
-      #   of significant_digits. If +false+, the # of fractional
+      # * <tt>:significant</tt> - If +true+, precision will be the number
+      #   of significant_digits. If +false+, the number of fractional
       #   digits (defaults to +false+).
       # * <tt>:separator</tt> - Sets the separator between the
       #   fractional and integer digits (defaults to ".").
@@ -141,7 +139,7 @@ module ActionView
       #   number_to_percentage(302.24398923423, precision: 5)              # => 302.24399%
       #   number_to_percentage(1000, locale: :fr)                          # => 1 000,000%
       #   number_to_percentage("98a")                                      # => 98a%
-      #   number_to_percentage(100, format: "%n  %")                       # => 100  %
+      #   number_to_percentage(100, format: "%n  %")                       # => 100.000  %
       #
       #   number_to_percentage("98a", raise: true)                         # => InvalidNumberError
       def number_to_percentage(number, options = {})
@@ -192,8 +190,8 @@ module ActionView
       #   (defaults to current locale).
       # * <tt>:precision</tt> - Sets the precision of the number
       #   (defaults to 3).
-      # * <tt>:significant</tt> - If +true+, precision will be the #
-      #   of significant_digits. If +false+, the # of fractional
+      # * <tt>:significant</tt> - If +true+, precision will be the number
+      #   of significant_digits. If +false+, the number of fractional
       #   digits (defaults to +false+).
       # * <tt>:separator</tt> - Sets the separator between the
       #   fractional and integer digits (defaults to ".").
@@ -240,8 +238,8 @@ module ActionView
       #   (defaults to current locale).
       # * <tt>:precision</tt> - Sets the precision of the number
       #   (defaults to 3).
-      # * <tt>:significant</tt> - If +true+, precision will be the #
-      #   of significant_digits. If +false+, the # of fractional
+      # * <tt>:significant</tt> - If +true+, precision will be the number
+      #   of significant_digits. If +false+, the number of fractional
       #   digits (defaults to +true+)
       # * <tt>:separator</tt> - Sets the separator between the
       #   fractional and integer digits (defaults to ".").
@@ -280,7 +278,7 @@ module ActionView
       # See <tt>number_to_human_size</tt> if you want to print a file
       # size.
       #
-      # You can also define you own unit-quantifier names if you want
+      # You can also define your own unit-quantifier names if you want
       # to use other decimal units (eg.: 1500 becomes "1.5
       # kilometers", 0.150 becomes "150 milliliters", etc). You may
       # define a wide range of unit quantifiers, even fractional ones
@@ -292,8 +290,8 @@ module ActionView
       #   (defaults to current locale).
       # * <tt>:precision</tt> - Sets the precision of the number
       #   (defaults to 3).
-      # * <tt>:significant</tt> - If +true+, precision will be the #
-      #   of significant_digits. If +false+, the # of fractional
+      # * <tt>:significant</tt> - If +true+, precision will be the number
+      #   of significant_digits. If +false+, the number of fractional
       #   digits (defaults to +true+)
       # * <tt>:separator</tt> - Sets the separator between the
       #   fractional and integer digits (defaults to ".").
diff --git a/actionview/lib/action_view/helpers/record_tag_helper.rb b/actionview/lib/action_view/helpers/record_tag_helper.rb
index 77c3e6d394..f7ee573035 100644
--- a/actionview/lib/action_view/helpers/record_tag_helper.rb
+++ b/actionview/lib/action_view/helpers/record_tag_helper.rb
@@ -1,108 +1,21 @@
-require 'action_view/record_identifier'
-
 module ActionView
-  # = Action View Record Tag Helpers
   module Helpers
     module RecordTagHelper
-      include ActionView::RecordIdentifier
-
-      # Produces a wrapper DIV element with id and class parameters that
-      # relate to the specified Active Record object. Usage example:
-      #
-      #    <%= div_for(@person, class: "foo") do %>
-      #       <%= @person.name %>
-      #    <% end %>
-      #
-      # produces:
-      #
-      #    <div id="person_123" class="person foo"> Joe Bloggs </div>
-      #
-      # You can also pass an array of Active Record objects, which will then
-      # get iterated over and yield each record as an argument for the block.
-      # For example:
-      #
-      #    <%= div_for(@people, class: "foo") do |person| %>
-      #      <%= person.name %>
-      #    <% end %>
-      #
-      # produces:
-      #
-      #    <div id="person_123" class="person foo"> Joe Bloggs </div>
-      #    <div id="person_124" class="person foo"> Jane Bloggs </div>
-      #
-      def div_for(record, *args, &block)
-        content_tag_for(:div, record, *args, &block)
+      def div_for(*)
+        raise NoMethodError, "The `div_for` method has been removed from " \
+          "Rails. To continue using it, add the `record_tag_helper` gem to " \
+          "your Gemfile:\n" \
+          "  gem 'record_tag_helper', '~> 1.0'\n" \
+          "Consult the Rails upgrade guide for details."
       end
 
-      # content_tag_for creates an HTML element with id and class parameters
-      # that relate to the specified Active Record object. For example:
-      #
-      #    <%= content_tag_for(:tr, @person) do %>
-      #      <td><%= @person.first_name %></td>
-      #      <td><%= @person.last_name %></td>
-      #    <% end %>
-      #
-      # would produce the following HTML (assuming @person is an instance of
-      # a Person object, with an id value of 123):
-      #
-      #    <tr id="person_123" class="person">....</tr>
-      #
-      # If you require the HTML id attribute to have a prefix, you can specify it:
-      #
-      #    <%= content_tag_for(:tr, @person, :foo) do %> ...
-      #
-      # produces:
-      #
-      #    <tr id="foo_person_123" class="person">...
-      #
-      # You can also pass an array of objects which this method will loop through
-      # and yield the current object to the supplied block, reducing the need for
-      # having to iterate through the object (using <tt>each</tt>) beforehand.
-      # For example (assuming @people is an array of Person objects):
-      #
-      #    <%= content_tag_for(:tr, @people) do |person| %>
-      #      <td><%= person.first_name %></td>
-      #      <td><%= person.last_name %></td>
-      #    <% end %>
-      #
-      # produces:
-      #
-      #    <tr id="person_123" class="person">...</tr>
-      #    <tr id="person_124" class="person">...</tr>
-      #
-      # content_tag_for also accepts a hash of options, which will be converted to
-      # additional HTML attributes. If you specify a <tt>:class</tt> value, it will be combined
-      # with the default class name for your object. For example:
-      #
-      #    <%= content_tag_for(:li, @person, class: "bar") %>...
-      #
-      # produces:
-      #
-      #    <li id="person_123" class="person bar">...
-      #
-      def content_tag_for(tag_name, single_or_multiple_records, prefix = nil, options = nil, &block)
-        options, prefix = prefix, nil if prefix.is_a?(Hash)
-
-        Array(single_or_multiple_records).map do |single_record|
-          content_tag_for_single_record(tag_name, single_record, prefix, options, &block)
-        end.join("\n").html_safe
+      def content_tag_for(*)
+        raise NoMethodError, "The `content_tag_for` method has been removed from " \
+          "Rails. To continue using it, add the `record_tag_helper` gem to " \
+          "your Gemfile:\n" \
+          "  gem 'record_tag_helper', '~> 1.0'\n" \
+          "Consult the Rails upgrade guide for details."
       end
-
-      private
-
-        # Called by <tt>content_tag_for</tt> internally to render a content tag
-        # for each record.
-        def content_tag_for_single_record(tag_name, record, prefix, options, &block)
-          options = options ? options.dup : {}
-          options[:class] = [ dom_class(record, prefix), options[:class] ].compact
-          options[:id]    = dom_id(record, prefix)
-
-          if block_given?
-            content_tag(tag_name, capture(record, &block), options)
-          else
-            content_tag(tag_name, "", options)
-          end
-        end
     end
   end
 end
diff --git a/actionview/lib/action_view/helpers/rendering_helper.rb b/actionview/lib/action_view/helpers/rendering_helper.rb
index 827932d8e2..c98f2d74a8 100644
--- a/actionview/lib/action_view/helpers/rendering_helper.rb
+++ b/actionview/lib/action_view/helpers/rendering_helper.rb
@@ -18,7 +18,7 @@ module ActionView
       #   performs HTML escape on the string first. Setting the content type as
       #   <tt>text/html</tt>.
       # * <tt>:body</tt> - Renders the text passed in, and inherits the content
-      #   type of <tt>text/html</tt> from <tt>ActionDispatch::Response</tt>
+      #   type of <tt>text/plain</tt> from <tt>ActionDispatch::Response</tt>
       #   object.
       #
       # If no options hash is passed or :update specified, the default is to render a partial and use the second parameter
diff --git a/actionview/lib/action_view/helpers/sanitize_helper.rb b/actionview/lib/action_view/helpers/sanitize_helper.rb
index e72e85ee5f..191a881de0 100644
--- a/actionview/lib/action_view/helpers/sanitize_helper.rb
+++ b/actionview/lib/action_view/helpers/sanitize_helper.rb
@@ -8,76 +8,77 @@ module ActionView
     # These helper methods extend Action View making them callable within your template files.
     module SanitizeHelper
       extend ActiveSupport::Concern
-      # This +sanitize+ helper will HTML encode all tags and strip all attributes that
-      # aren't specifically allowed.
+      # Sanitizes HTML input, stripping all tags and attributes that aren't whitelisted.
       #
-      # It also strips href/src tags with invalid protocols, like javascript: especially.
-      # It does its best to counter any  tricks that hackers may use, like throwing in
-      # unicode/ascii/hex values to get past the javascript: filters. Check out
-      # the extensive test suite.
+      # It also strips href/src attributes with unsafe protocols like
+      # <tt>javascript:</tt>, while also protecting against attempts to use Unicode,
+      # ASCII, and hex character references to work around these protocol filters.
       #
-      #   <%= sanitize @article.body %>
+      # The default sanitizer is Rails::Html::WhiteListSanitizer. See {Rails HTML
+      # Sanitizers}[https://github.com/rails/rails-html-sanitizer] for more information.
       #
-      # You can add or remove tags/attributes if you want to customize it a bit.
-      # See ActionView::Base for full docs on the available options. You can add
-      # tags/attributes for single uses of +sanitize+ by passing either the
-      # <tt>:attributes</tt> or <tt>:tags</tt> options:
+      # Custom sanitization rules can also be provided.
       #
-      # Normal Use
-      #
-      #   <%= sanitize @article.body %>
+      # Please note that sanitizing user-provided text does not guarantee that the
+      # resulting markup is valid or even well-formed. For example, the output may still
+      # contain unescaped characters like <tt><</tt>, <tt>></tt>, or <tt>&</tt>.
       #
-      # Custom Use - Custom Scrubber
-      # (supply a Loofah::Scrubber that does the sanitization)
+      # ==== Options
       #
-      # scrubber can either wrap a block:
-      # scrubber = Loofah::Scrubber.new do |node|
-      #   node.text = "dawn of cats"
-      # end
+      # * <tt>:tags</tt> - An array of allowed tags.
+      # * <tt>:attributes</tt> - An array of allowed attributes.
+      # * <tt>:scrubber</tt> - A {Rails::Html scrubber}[https://github.com/rails/rails-html-sanitizer]
+      #   or {Loofah::Scrubber}[https://github.com/flavorjones/loofah] object that
+      #   defines custom sanitization rules. A custom scrubber takes precedence over
+      #   custom tags and attributes.
       #
-      # or be a subclass of Loofah::Scrubber which responds to scrub:
-      # class KittyApocalypse < Loofah::Scrubber
-      #   def scrub(node)
-      #     node.text = "dawn of cats"
-      #   end
-      # end
-      # scrubber = KittyApocalypse.new
+      # ==== Examples
       #
-      # <%= sanitize @article.body, scrubber: scrubber %>
+      # Normal use:
       #
-      # A custom scrubber takes precedence over custom tags and attributes
-      # Learn more about scrubbers here: https://github.com/flavorjones/loofah
+      #   <%= sanitize @comment.body %>
       #
-      # Custom Use - tags and attributes
-      # (only the mentioned tags and attributes are allowed, nothing else)
+      # Providing custom whitelisted tags and attributes:
       #
-      #   <%= sanitize @article.body, tags: %w(table tr td), attributes: %w(id class style) %>
+      #   <%= sanitize @comment.body, tags: %w(strong em a), attributes: %w(href) %>
       #
-      # Add table tags to the default allowed tags
+      # Providing a custom Rails::Html scrubber:
       #
-      #   class Application < Rails::Application
-      #     config.action_view.sanitized_allowed_tags = ['table', 'tr', 'td']
-      #   end
+      #   class CommentScrubber < Rails::Html::PermitScrubber
+      #     def allowed_node?(node)
+      #       !%w(form script comment blockquote).include?(node.name)
+      #     end
       #
-      # Remove tags to the default allowed tags
+      #     def skip_node?(node)
+      #       node.text?
+      #     end
       #
-      #   class Application < Rails::Application
-      #     config.after_initialize do
-      #       ActionView::Base.sanitized_allowed_tags.delete 'div'
+      #     def scrub_attribute?(name)
+      #       name == 'style'
       #     end
       #   end
       #
-      # Change allowed default attributes
+      #   <%= sanitize @comment.body, scrubber: CommentScrubber.new %>
+      #
+      # See {Rails HTML Sanitizer}[https://github.com/rails/rails-html-sanitizer] for
+      # documentation about Rails::Html scrubbers.
       #
-      #   class Application < Rails::Application
-      #     config.action_view.sanitized_allowed_attributes = ['id', 'class', 'style']
+      # Providing a custom Loofah::Scrubber:
+      #
+      #   scrubber = Loofah::Scrubber.new do |node|
+      #     node.remove if node.name == 'script'
       #   end
       #
-      # Please note that sanitizing user-provided text does not guarantee that the
-      # resulting markup is valid (conforming to a document type) or even well-formed.
-      # The output may still contain e.g. unescaped '<', '>', '&' characters and
-      # confuse browsers.
+      #   <%= sanitize @comment.body, scrubber: scrubber %>
+      #
+      # See {Loofah's documentation}[https://github.com/flavorjones/loofah] for more
+      # information about defining custom Loofah::Scrubber objects.
       #
+      # To set the default allowed tags or attributes across your application:
+      #
+      #   # In config/application.rb
+      #   config.action_view.sanitized_allowed_tags = ['strong', 'em', 'a']
+      #   config.action_view.sanitized_allowed_attributes = ['href', 'title']
       def sanitize(html, options = {})
         self.class.white_list_sanitizer.sanitize(html, options).try(:html_safe)
       end
@@ -87,9 +88,7 @@ module ActionView
         self.class.white_list_sanitizer.sanitize_css(style)
       end
 
-      # Strips all HTML tags from the +html+, including comments. This uses
-      # Nokogiri for tokenization (via Loofah) and so its HTML parsing ability
-      # is limited by that of Nokogiri.
+      # Strips all HTML tags from +html+, including comments.
       #
       #   strip_tags("Strip <i>these</i> tags!")
       #   # => Strip these tags!
@@ -100,10 +99,10 @@ module ActionView
       #   strip_tags("<div id='top-bar'>Welcome to my website!</div>")
       #   # => Welcome to my website!
       def strip_tags(html)
-        self.class.full_sanitizer.sanitize(html)
+        self.class.full_sanitizer.sanitize(html, encode_special_chars: false)
       end
 
-      # Strips all link tags from +text+ leaving just the link text.
+      # Strips all link tags from +html+ leaving just the link text.
       #
       #   strip_links('<a href="http://www.rubyonrails.org">Ruby on Rails</a>')
       #   # => Ruby on Rails
@@ -121,7 +120,7 @@ module ActionView
         attr_writer :full_sanitizer, :link_sanitizer, :white_list_sanitizer
 
         # Vendors the full, link and white list sanitizers.
-        # Provided strictly for compabitility and can be removed in Rails 5.
+        # Provided strictly for compatibility and can be removed in Rails 5.
         def sanitizer_vendor
           Rails::Html::Sanitizer
         end
@@ -166,30 +165,6 @@ module ActionView
         def white_list_sanitizer
           @white_list_sanitizer ||= sanitizer_vendor.white_list_sanitizer.new
         end
-
-        ##
-        # :method: sanitized_allowed_tags=
-        #
-        # :call-seq: sanitized_allowed_tags=(tags)
-        #
-        # Replaces the allowed tags for the +sanitize+ helper.
-        #
-        #   class Application < Rails::Application
-        #     config.action_view.sanitized_allowed_tags = ['table', 'tr', 'td']
-        #   end
-        #
-
-        ##
-        # :method: sanitized_allowed_attributes=
-        #
-        # :call-seq: sanitized_allowed_attributes=(attributes)
-        #
-        # Replaces the allowed HTML attributes for the +sanitize+ helper.
-        #
-        #   class Application < Rails::Application
-        #     config.action_view.sanitized_allowed_attributes = ['onclick', 'longdesc']
-        #   end
-        #
       end
     end
   end
diff --git a/actionview/lib/action_view/helpers/tag_helper.rb b/actionview/lib/action_view/helpers/tag_helper.rb
index a87c223a71..2562504896 100644
--- a/actionview/lib/action_view/helpers/tag_helper.rb
+++ b/actionview/lib/action_view/helpers/tag_helper.rb
@@ -22,9 +22,10 @@ module ActionView
 
       TAG_PREFIXES = ['aria', 'data', :aria, :data].to_set
 
-      PRE_CONTENT_STRINGS = {
-        :textarea => "\n"
-      }
+      PRE_CONTENT_STRINGS             = Hash.new { "".freeze }
+      PRE_CONTENT_STRINGS[:textarea]  = "\n"
+      PRE_CONTENT_STRINGS["textarea"] = "\n"
+
 
       # Returns an empty HTML tag of type +name+ which by default is XHTML
       # compliant. Set +open+ to true to create an open tag compatible
@@ -143,24 +144,30 @@ module ActionView
         def content_tag_string(name, content, options, escape = true)
           tag_options = tag_options(options, escape) if options
           content     = ERB::Util.unwrapped_html_escape(content) if escape
-          "<#{name}#{tag_options}>#{PRE_CONTENT_STRINGS[name.to_sym]}#{content}</#{name}>".html_safe
+          "<#{name}#{tag_options}>#{PRE_CONTENT_STRINGS[name]}#{content}</#{name}>".html_safe
         end
 
         def tag_options(options, escape = true)
           return if options.blank?
-          attrs = []
+          output = ""
+          sep    = " ".freeze
           options.each_pair do |key, value|
             if TAG_PREFIXES.include?(key) && value.is_a?(Hash)
               value.each_pair do |k, v|
-                attrs << prefix_tag_option(key, k, v, escape)
+                output << sep
+                output << prefix_tag_option(key, k, v, escape)
               end
             elsif BOOLEAN_ATTRIBUTES.include?(key)
-              attrs << boolean_tag_option(key) if value
+              if value
+                output << sep
+                output << boolean_tag_option(key)
+              end
             elsif !value.nil?
-              attrs << tag_option(key, value, escape)
+              output << sep
+              output << tag_option(key, value, escape)
             end
           end
-          " #{attrs * ' '}" unless attrs.empty?
+          output unless output.empty?
         end
 
         def prefix_tag_option(prefix, key, value, escape)
@@ -177,7 +184,7 @@ module ActionView
 
         def tag_option(key, value, escape)
           if value.is_a?(Array)
-            value = escape ? safe_join(value, " ") : value.join(" ")
+            value = escape ? safe_join(value, " ".freeze) : value.join(" ".freeze)
           else
             value = escape ? ERB::Util.unwrapped_html_escape(value) : value
           end
diff --git a/actionview/lib/action_view/helpers/tags.rb b/actionview/lib/action_view/helpers/tags.rb
index 45c75d10c0..a4f6eb0150 100644
--- a/actionview/lib/action_view/helpers/tags.rb
+++ b/actionview/lib/action_view/helpers/tags.rb
@@ -5,6 +5,7 @@ module ActionView
 
       eager_autoload do
         autoload :Base
+        autoload :Translator
         autoload :CheckBox
         autoload :CollectionCheckBoxes
         autoload :CollectionRadioButtons
diff --git a/actionview/lib/action_view/helpers/tags/base.rb b/actionview/lib/action_view/helpers/tags/base.rb
index 7740c60eac..d57f26ba4f 100644
--- a/actionview/lib/action_view/helpers/tags/base.rb
+++ b/actionview/lib/action_view/helpers/tags/base.rb
@@ -14,7 +14,7 @@ module ActionView
           @object_name.sub!(/\[\]$/,"") || @object_name.sub!(/\[\]\]$/,"]")
           @object = retrieve_object(options.delete(:object))
           @options = options
-          @auto_index = retrieve_autoindex(Regexp.last_match.pre_match) if Regexp.last_match
+          @auto_index = Regexp.last_match ? retrieve_autoindex(Regexp.last_match.pre_match) : nil
         end
 
         # This is what child classes implement.
@@ -79,35 +79,30 @@ module ActionView
         end
 
         def add_default_name_and_id(options)
-          if options.has_key?("index")
-            options["name"] ||= options.fetch("name"){ tag_name_with_index(options["index"], options["multiple"]) }
-            options["id"] = options.fetch("id"){ tag_id_with_index(options["index"]) }
-            options.delete("index")
-          elsif defined?(@auto_index)
-            options["name"] ||= options.fetch("name"){ tag_name_with_index(@auto_index, options["multiple"]) }
-            options["id"] = options.fetch("id"){ tag_id_with_index(@auto_index) }
-          else
-            options["name"] ||= options.fetch("name"){ tag_name(options["multiple"]) }
-            options["id"] = options.fetch("id"){ tag_id }
+          index = name_and_id_index(options)
+          options["name"] = options.fetch("name"){ tag_name(options["multiple"], index) }
+          options["id"] = options.fetch("id"){ tag_id(index) }
+          if namespace = options.delete("namespace")
+            options['id'] = options['id'] ? "#{namespace}_#{options['id']}" : namespace
           end
-
-          options["id"] = [options.delete('namespace'), options["id"]].compact.join("_").presence
-        end
-
-        def tag_name(multiple = false)
-          "#{@object_name}[#{sanitized_method_name}]#{"[]" if multiple}"
         end
 
-        def tag_name_with_index(index, multiple = false)
-          "#{@object_name}[#{index}][#{sanitized_method_name}]#{"[]" if multiple}"
-        end
-
-        def tag_id
-          "#{sanitized_object_name}_#{sanitized_method_name}"
+        def tag_name(multiple = false, index = nil)
+          # a little duplication to construct less strings
+          if index
+            "#{@object_name}[#{index}][#{sanitized_method_name}]#{"[]" if multiple}"
+          else
+            "#{@object_name}[#{sanitized_method_name}]#{"[]" if multiple}"
+          end
         end
 
-        def tag_id_with_index(index)
-          "#{sanitized_object_name}_#{index}_#{sanitized_method_name}"
+        def tag_id(index = nil)
+          # a little duplication to construct less strings
+          if index
+            "#{sanitized_object_name}_#{index}_#{sanitized_method_name}"
+          else
+            "#{sanitized_object_name}_#{sanitized_method_name}"
+          end
         end
 
         def sanitized_object_name
@@ -125,7 +120,12 @@ module ActionView
         def select_content_tag(option_tags, options, html_options)
           html_options = html_options.stringify_keys
           add_default_name_and_id(html_options)
-          options[:include_blank] ||= true unless options[:prompt] || select_not_required?(html_options)
+
+          if placeholder_required?(html_options)
+            raise ArgumentError, "include_blank cannot be false for a required field." if options[:include_blank] == false
+            options[:include_blank] ||= true unless options[:prompt]
+          end
+
           value = options.fetch(:selected) { value(object) }
           select = content_tag("select", add_options(option_tags, options, value), html_options)
 
@@ -136,8 +136,9 @@ module ActionView
           end
         end
 
-        def select_not_required?(html_options)
-          !html_options["required"] || html_options["multiple"] || html_options["size"].to_i > 1
+        def placeholder_required?(html_options)
+          # See https://html.spec.whatwg.org/multipage/forms.html#attr-select-required
+          html_options["required"] && !html_options["multiple"] && html_options.fetch("size", 1).to_i == 1
         end
 
         def add_options(option_tags, options, value = nil)
@@ -149,6 +150,10 @@ module ActionView
           end
           option_tags
         end
+
+        def name_and_id_index(options)
+          options.key?("index") ?  options.delete("index") || "" : @auto_index
+        end
       end
     end
   end
diff --git a/actionview/lib/action_view/helpers/tags/collection_check_boxes.rb b/actionview/lib/action_view/helpers/tags/collection_check_boxes.rb
index 6242a2a085..3256d44e18 100644
--- a/actionview/lib/action_view/helpers/tags/collection_check_boxes.rb
+++ b/actionview/lib/action_view/helpers/tags/collection_check_boxes.rb
@@ -9,29 +9,13 @@ module ActionView
         class CheckBoxBuilder < Builder # :nodoc:
           def check_box(extra_html_options={})
             html_options = extra_html_options.merge(@input_html_options)
+            html_options[:multiple] = true
             @template_object.check_box(@object_name, @method_name, html_options, @value, nil)
           end
         end
 
         def render(&block)
-          rendered_collection = render_collection do |item, value, text, default_html_options|
-            default_html_options[:multiple] = true
-            builder = instantiate_builder(CheckBoxBuilder, item, value, text, default_html_options)
-
-            if block_given?
-              @template_object.capture(builder, &block)
-            else
-              render_component(builder)
-            end
-          end
-
-          # Append a hidden field to make sure something will be sent back to the
-          # server if all check boxes are unchecked.
-          if @options.fetch(:include_hidden, true)
-            rendered_collection + hidden_field
-          else
-            rendered_collection
-          end
+          render_collection_for(CheckBoxBuilder, &block)
         end
 
         private
@@ -39,18 +23,6 @@ module ActionView
         def render_component(builder)
           builder.check_box + builder.label
         end
-
-        def hidden_field
-          hidden_name = @html_options[:name]
-
-          hidden_name ||= if @options.has_key?(:index)
-            "#{tag_name_with_index(@options[:index])}[]"
-          else
-            "#{tag_name}[]"
-          end
-
-          @template_object.hidden_field_tag(hidden_name, "", id: nil)
-        end
       end
     end
   end
diff --git a/actionview/lib/action_view/helpers/tags/collection_helpers.rb b/actionview/lib/action_view/helpers/tags/collection_helpers.rb
index 8050638363..b87b4281d6 100644
--- a/actionview/lib/action_view/helpers/tags/collection_helpers.rb
+++ b/actionview/lib/action_view/helpers/tags/collection_helpers.rb
@@ -19,6 +19,8 @@ module ActionView
 
           def label(label_html_options={}, &block)
             html_options = @input_html_options.slice(:index, :namespace).merge(label_html_options)
+            html_options[:for] ||= @input_html_options[:id] if @input_html_options[:id]
+
             @template_object.label(@object_name, @sanitized_attribute_name, @text, html_options, &block)
           end
         end
@@ -79,6 +81,32 @@ module ActionView
             yield item, value, text, default_html_options.merge(additional_html_options)
           end.join.html_safe
         end
+
+        def render_collection_for(builder_class, &block) #:nodoc:
+          options = @options.stringify_keys
+          rendered_collection = render_collection do |item, value, text, default_html_options|
+            builder = instantiate_builder(builder_class, item, value, text, default_html_options)
+
+            if block_given?
+              @template_object.capture(builder, &block)
+            else
+              render_component(builder)
+            end
+          end
+
+          # Append a hidden field to make sure something will be sent back to the
+          # server if all radio buttons are unchecked.
+          if options.fetch('include_hidden', true)
+            rendered_collection + hidden_field
+          else
+            rendered_collection
+          end
+        end
+
+        def hidden_field #:nodoc:
+          hidden_name = @html_options[:name] || "#{tag_name(false, @options[:index])}[]"
+          @template_object.hidden_field_tag(hidden_name, "", id: nil)
+        end
       end
     end
   end
diff --git a/actionview/lib/action_view/helpers/tags/collection_radio_buttons.rb b/actionview/lib/action_view/helpers/tags/collection_radio_buttons.rb
index 20be34c1f2..21aaf122f8 100644
--- a/actionview/lib/action_view/helpers/tags/collection_radio_buttons.rb
+++ b/actionview/lib/action_view/helpers/tags/collection_radio_buttons.rb
@@ -14,15 +14,7 @@ module ActionView
         end
 
         def render(&block)
-          render_collection do |item, value, text, default_html_options|
-            builder = instantiate_builder(RadioButtonBuilder, item, value, text, default_html_options)
-
-            if block_given?
-              @template_object.capture(builder, &block)
-            else
-              render_component(builder)
-            end
-          end
+          render_collection_for(RadioButtonBuilder, &block)
         end
 
         private
diff --git a/actionview/lib/action_view/helpers/tags/label.rb b/actionview/lib/action_view/helpers/tags/label.rb
index 08a23e497e..b31d5fda66 100644
--- a/actionview/lib/action_view/helpers/tags/label.rb
+++ b/actionview/lib/action_view/helpers/tags/label.rb
@@ -15,20 +15,10 @@ module ActionView
 
           def translation
             method_and_value = @tag_value.present? ? "#{@method_name}.#{@tag_value}" : @method_name
-            @object_name.gsub!(/\[(.*)_attributes\]\[\d+\]/, '.\1')
-
-            if object.respond_to?(:to_model)
-              key = object.model_name.i18n_key
-              i18n_default = ["#{key}.#{method_and_value}".to_sym, ""]
-            end
-
-            i18n_default ||= ""
-            content = I18n.t("#{@object_name}.#{method_and_value}", :default => i18n_default, :scope => "helpers.label").presence
-
-            content ||= if object && object.class.respond_to?(:human_attribute_name)
-                          object.class.human_attribute_name(method_and_value)
-                        end
 
+            content ||= Translator
+              .new(object, @object_name, method_and_value, scope: "helpers.label")
+              .translate
             content ||= @method_name.humanize
 
             content
diff --git a/actionview/lib/action_view/helpers/tags/placeholderable.rb b/actionview/lib/action_view/helpers/tags/placeholderable.rb
index ae67bc13af..cf7b117614 100644
--- a/actionview/lib/action_view/helpers/tags/placeholderable.rb
+++ b/actionview/lib/action_view/helpers/tags/placeholderable.rb
@@ -7,24 +7,12 @@ module ActionView
 
           if tag_value = @options[:placeholder]
             placeholder = tag_value if tag_value.is_a?(String)
-
-            object_name = @object_name.gsub(/\[(.*)_attributes\]\[\d+\]/, '.\1')
             method_and_value = tag_value.is_a?(TrueClass) ? @method_name : "#{@method_name}.#{tag_value}"
 
-            if object.respond_to?(:to_model)
-              key = object.class.model_name.i18n_key
-              i18n_default = ["#{key}.#{method_and_value}".to_sym, ""]
-            end
-
-            i18n_default ||= ""
-            placeholder ||= I18n.t("#{object_name}.#{method_and_value}", :default => i18n_default, :scope => "helpers.placeholder").presence
-
-            placeholder ||= if object && object.class.respond_to?(:human_attribute_name)
-                          object.class.human_attribute_name(method_and_value)
-                        end
-
+            placeholder ||= Tags::Translator
+              .new(object, @object_name, method_and_value, scope: "helpers.placeholder")
+              .translate
             placeholder ||= @method_name.humanize
-
             @options[:placeholder] = placeholder
           end
         end
diff --git a/actionview/lib/action_view/helpers/tags/translator.rb b/actionview/lib/action_view/helpers/tags/translator.rb
new file mode 100644
index 0000000000..8b6655481d
--- /dev/null
+++ b/actionview/lib/action_view/helpers/tags/translator.rb
@@ -0,0 +1,40 @@
+module ActionView
+  module Helpers
+    module Tags # :nodoc:
+      class Translator # :nodoc:
+        def initialize(object, object_name, method_and_value, scope:)
+          @object_name = object_name.gsub(/\[(.*)_attributes\]\[\d+\]/, '.\1')
+          @method_and_value = method_and_value
+          @scope = scope
+          @model = object.respond_to?(:to_model) ? object.to_model : nil
+        end
+
+        def translate
+          translated_attribute = I18n.t("#{object_name}.#{method_and_value}", default: i18n_default, scope: scope).presence
+          translated_attribute || human_attribute_name
+        end
+
+        protected
+
+        attr_reader :object_name, :method_and_value, :scope, :model
+
+        private
+
+        def i18n_default
+          if model
+            key = model.model_name.i18n_key
+            ["#{key}.#{method_and_value}".to_sym, ""]
+          else
+            ""
+          end
+        end
+
+        def human_attribute_name
+          if model && model.class.respond_to?(:human_attribute_name)
+            model.class.human_attribute_name(method_and_value)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/actionview/lib/action_view/helpers/text_helper.rb b/actionview/lib/action_view/helpers/text_helper.rb
index 2c40ed1832..432693bc23 100644
--- a/actionview/lib/action_view/helpers/text_helper.rb
+++ b/actionview/lib/action_view/helpers/text_helper.rb
@@ -103,7 +103,9 @@ module ActionView
       # Highlights one or more +phrases+ everywhere in +text+ by inserting it into
       # a <tt>:highlighter</tt> string. The highlighter can be specialized by passing <tt>:highlighter</tt>
       # as a single-quoted string with <tt>\1</tt> where the phrase is to be inserted (defaults to
-      # '<mark>\1</mark>') or passing a block that receives each matched term.
+      # '<mark>\1</mark>') or passing a block that receives each matched term. By default +text+
+      # is sanitized to prevent possible XSS attacks. If the input is trustworthy, passing false
+      # for <tt>:sanitize</tt> will turn sanitizing off.
       #
       #   highlight('You searched for: rails', 'rails')
       #   # => You searched for: <mark>rails</mark>
@@ -122,6 +124,9 @@ module ActionView
       #
       #   highlight('You searched for: rails', 'rails') { |match| link_to(search_path(q: match, match)) }
       #   # => You searched for: <a href="search?q=rails">rails</a>
+      #
+      #   highlight('<a href="javascript:alert(\'no!\')">ruby</a> on rails', 'rails', sanitize: false)
+      #   # => "<a>ruby</a> on <mark>rails</mark>"
       def highlight(text, phrases, options = {})
         text = sanitize(text) if options.fetch(:sanitize, true)
 
@@ -201,6 +206,11 @@ module ActionView
       # +plural+ is supplied, it will use that when count is > 1, otherwise
       # it will use the Inflector to determine the plural form.
       #
+      # If passed an optional +locale:+ parameter, the word will be pluralized
+      # using rules defined for that language (you must define your own
+      # inflection rules for languages other than English).  See
+      # ActiveSupport::Inflector.pluralize
+      #
       #   pluralize(1, 'person')
       #   # => 1 person
       #
@@ -212,11 +222,14 @@ module ActionView
       #
       #   pluralize(0, 'person')
       #   # => 0 people
-      def pluralize(count, singular, plural = nil)
+      #
+      #   pluralize(2, 'Person', locale: :de)
+      #   # => 2 Personen
+      def pluralize(count, singular, plural = nil, locale: nil)
         word = if (count == 1 || count =~ /^1(\.0+)?$/)
           singular
         else
-          plural || singular.pluralize
+          plural || singular.pluralize(locale)
         end
 
         "#{count || 0} #{word}"
@@ -237,12 +250,15 @@ module ActionView
       #
       #   word_wrap('Once upon a time', line_width: 1)
       #   # => Once\nupon\na\ntime
-      def word_wrap(text, options = {})
-        line_width = options.fetch(:line_width, 80)
-
+      #
+      #   You can also specify a custom +break_sequence+ ("\n" by default)
+      #
+      #   word_wrap('Once upon a time', line_width: 1, break_sequence: "\r\n")
+      #   # => Once\r\nupon\r\na\r\ntime
+      def word_wrap(text, line_width: 80, break_sequence: "\n")
         text.split("\n").collect! do |line|
-          line.length > line_width ? line.gsub(/(.{1,#{line_width}})(\s+|$)/, "\\1\n").strip : line
-        end * "\n"
+          line.length > line_width ? line.gsub(/(.{1,#{line_width}})(\s+|$)/, "\\1#{break_sequence}").strip : line
+        end * break_sequence
       end
 
       # Returns +text+ transformed into HTML using simple formatting rules.
diff --git a/actionview/lib/action_view/helpers/translation_helper.rb b/actionview/lib/action_view/helpers/translation_helper.rb
index 342361217c..dde1ef22ac 100644
--- a/actionview/lib/action_view/helpers/translation_helper.rb
+++ b/actionview/lib/action_view/helpers/translation_helper.rb
@@ -7,48 +7,65 @@ module ActionView
   module Helpers
     module TranslationHelper
       include TagHelper
-      # Delegates to <tt>I18n#translate</tt> but also performs three additional functions.
+      # Delegates to <tt>I18n#translate</tt> but also performs three additional
+      # functions.
       #
-      # First, it will ensure that any thrown +MissingTranslation+ messages will be turned
-      # into inline spans that:
+      # First, it will ensure that any thrown +MissingTranslation+ messages will
+      # be rendered as inline spans that:
       #
-      #   * have a "translation-missing" class set,
-      #   * contain the missing key as a title attribute and
-      #   * a titleized version of the last key segment as a text.
+      # * Have a <tt>translation-missing</tt> class applied
+      # * Contain the missing key as the value of the +title+ attribute
+      # * Have a titleized version of the last key segment as text
       #
-      # E.g. the value returned for a missing translation key :"blog.post.title" will be
-      # <span class="translation_missing" title="translation missing: en.blog.post.title">Title</span>.
-      # This way your views will display rather reasonable strings but it will still
-      # be easy to spot missing translations.
+      # For example, the value returned for the missing translation key
+      # <tt>"blog.post.title"</tt> will be:
       #
-      # Second, it'll scope the key by the current partial if the key starts
-      # with a period. So if you call <tt>translate(".foo")</tt> from the
-      # <tt>people/index.html.erb</tt> template, you'll actually be calling
-      # <tt>I18n.translate("people.index.foo")</tt>. This makes it less repetitive
-      # to translate many keys within the same partials and gives you a simple framework
-      # for scoping them consistently. If you don't prepend the key with a period,
-      # nothing is converted.
+      #    <span
+      #      class="translation_missing"
+      #      title="translation missing: en.blog.post.title">Title</span>
       #
-      # Third, it'll mark the translation as safe HTML if the key has the suffix
-      # "_html" or the last element of the key is the word "html". For example,
-      # calling translate("footer_html") or translate("footer.html") will return
-      # a safe HTML string that won't be escaped by other HTML helper methods. This
-      # naming convention helps to identify translations that include HTML tags so that
-      # you know what kind of output to expect when you call translate in a template.
+      # This allows for views to display rather reasonable strings while still
+      # giving developers a way to find missing translations.
+      #
+      # If you would prefer missing translations to raise an error, you can
+      # opt out of span-wrapping behavior globally by setting
+      # <tt>ActionView::Base.raise_on_missing_translations = true</tt> or
+      # individually by passing <tt>raise: true</tt> as an option to
+      # <tt>translate</tt>.
+      #
+      # Second, if the key starts with a period <tt>translate</tt> will scope
+      # the key by the current partial. Calling <tt>translate(".foo")</tt> from
+      # the <tt>people/index.html.erb</tt> template is equivalent to calling
+      # <tt>translate("people.index.foo")</tt>. This makes it less
+      # repetitive to translate many keys within the same partial and provides
+      # a convention to scope keys consistently.
+      #
+      # Third, the translation will be marked as <tt>html_safe</tt> if the key
+      # has the suffix "_html" or the last element of the key is "html". Calling
+      # <tt>translate("footer_html")</tt> or <tt>translate("footer.html")</tt>
+      # will return an HTML safe string that won't be escaped by other HTML
+      # helper methods. This naming convention helps to identify translations
+      # that include HTML tags so that you know what kind of output to expect
+      # when you call translate in a template and translators know which keys
+      # they can provide HTML values for.
       def translate(key, options = {})
         options = options.dup
-        remaining_defaults = Array(options.delete(:default))
-        options[:default] = remaining_defaults.shift if remaining_defaults.first.kind_of? String
+        has_default = options.has_key?(:default)
+        remaining_defaults = Array(options.delete(:default)).compact
+
+        if has_default && !remaining_defaults.first.kind_of?(Symbol)
+          options[:default] = remaining_defaults
+        end
 
         # If the user has explicitly decided to NOT raise errors, pass that option to I18n.
         # Otherwise, tell I18n to raise an exception, which we rescue further in this method.
         # Note: `raise_error` refers to us re-raising the error in this method. I18n is forced to raise by default.
-        if options[:raise] == false || (options.key?(:rescue_format) && options[:rescue_format].nil?)
+        if options[:raise] == false
           raise_error = false
-          options[:raise] = false
+          i18n_raise = false
         else
-          raise_error = options[:raise] || options[:rescue_format] || ActionView::Base.raise_on_missing_translations
-          options[:raise] = true
+          raise_error = options[:raise] || ActionView::Base.raise_on_missing_translations
+          i18n_raise = true
         end
 
         if html_safe_translation_key?(key)
@@ -58,11 +75,11 @@ module ActionView
               html_safe_options[name] = ERB::Util.html_escape(value.to_s)
             end
           end
-          translation = I18n.translate(scope_key_by_partial(key), html_safe_options)
+          translation = I18n.translate(scope_key_by_partial(key), html_safe_options.merge(raise: i18n_raise))
 
           translation.respond_to?(:html_safe) ? translation.html_safe : translation
         else
-          I18n.translate(scope_key_by_partial(key), options)
+          I18n.translate(scope_key_by_partial(key), options.merge(raise: i18n_raise))
         end
       rescue I18n::MissingTranslationData => e
         if remaining_defaults.present?
@@ -71,7 +88,14 @@ module ActionView
           raise e if raise_error
 
           keys = I18n.normalize_keys(e.locale, e.key, e.options[:scope])
-          content_tag('span', keys.last.to_s.titleize, :class => 'translation_missing', :title => "translation missing: #{keys.join('.')}")
+          title = "translation missing: #{keys.join('.')}"
+
+          interpolations = options.except(:default)
+          if interpolations.any?
+            title << ", " << interpolations.map { |k, v| "#{k}: #{ERB::Util.html_escape(v)}" }.join(', ')
+          end
+
+          content_tag('span', keys.last.to_s.titleize, class: 'translation_missing', title: title)
         end
       end
       alias :t :translate
diff --git a/actionview/lib/action_view/helpers/url_helper.rb b/actionview/lib/action_view/helpers/url_helper.rb
index 8c2d5705f1..5684de35e8 100644
--- a/actionview/lib/action_view/helpers/url_helper.rb
+++ b/actionview/lib/action_view/helpers/url_helper.rb
@@ -46,9 +46,9 @@ module ActionView
       end
       protected :_back_url
 
-      # Creates a link tag of the given +name+ using a URL created by the set of +options+.
+      # Creates an anchor element of the given +name+ using a URL created by the set of +options+.
       # See the valid options in the documentation for +url_for+. It's also possible to
-      # pass a String instead of an options hash, which generates a link tag that uses the
+      # pass a String instead of an options hash, which generates an anchor element that uses the
       # value of the String as the href for the link. Using a <tt>:back</tt> Symbol instead
       # of an options hash will generate a link to the referrer (a JavaScript back link
       # will be used in place of a referrer if none exists). If +nil+ is passed as the name
@@ -172,6 +172,11 @@ module ActionView
       #
       #   link_to "Visit Other Site", "http://www.rubyonrails.org/", data: { confirm: "Are you sure?" }
       #   # => <a href="http://www.rubyonrails.org/" data-confirm="Are you sure?">Visit Other Site</a>
+      #
+      # Also you can set any link attributes such as <tt>target</tt>, <tt>rel</tt>, <tt>type</tt>:
+      #
+      #   link_to "External link", "http://www.rubyonrails.org/", target: "_blank", rel: "nofollow"
+      #   # => <a href="http://www.rubyonrails.org/" target="_blank" rel="nofollow">External link</a>
       def link_to(name = nil, options = nil, html_options = nil, &block)
         html_options, options, name = options, name, block if block_given?
         options ||= {}
@@ -179,9 +184,9 @@ module ActionView
         html_options = convert_options_to_data_attributes(options, html_options)
 
         url = url_for(options)
-        html_options['href'] ||= url
+        html_options["href".freeze] ||= url
 
-        content_tag(:a, name || url, html_options, &block)
+        content_tag("a".freeze, name || url, html_options, &block)
       end
 
       # Generates a form containing a single button that submits to the URL created
@@ -280,9 +285,7 @@ module ActionView
         html_options, options = options, name if block_given?
         options      ||= {}
         html_options ||= {}
-
         html_options = html_options.stringify_keys
-        convert_boolean_attributes!(html_options, %w(disabled))
 
         url    = options.is_a?(String) ? options : url_for(options)
         remote = html_options.delete('remote')
@@ -294,8 +297,9 @@ module ActionView
         form_method  = method == 'get' ? 'get' : 'post'
         form_options = html_options.delete('form') || {}
         form_options[:class] ||= html_options.delete('form_class') || 'button_to'
-        form_options.merge!(method: form_method, action: url)
-        form_options.merge!("data-remote" => "true") if remote
+        form_options[:method] = form_method
+        form_options[:action] = url
+        form_options[:'data-remote'] = true if remote
 
         request_token_tag = form_method == 'post' ? token_tag : ''
 
@@ -459,70 +463,59 @@ module ActionView
         html_options = (html_options || {}).stringify_keys
 
         extras = %w{ cc bcc body subject reply_to }.map! { |item|
-          option = html_options.delete(item) || next
-          "#{item.dasherize}=#{Rack::Utils.escape_path(option)}"
+          option = html_options.delete(item).presence || next
+          "#{item.dasherize}=#{ERB::Util.url_encode(option)}"
         }.compact
         extras = extras.empty? ? '' : '?' + extras.join('&')
 
-        html_options["href"] = "mailto:#{email_address}#{extras}"
+        encoded_email_address = ERB::Util.url_encode(email_address).gsub("%40", "@")
+        html_options["href"] = "mailto:#{encoded_email_address}#{extras}"
 
-        content_tag(:a, name || email_address, html_options, &block)
+        content_tag("a".freeze, name || email_address, html_options, &block)
       end
 
       # True if the current request URI was generated by the given +options+.
       #
       # ==== Examples
-      # Let's say we're in the <tt>http://www.example.com/shop/checkout?order=desc</tt> action.
+      # Let's say we're in the <tt>http://www.example.com/shop/checkout?order=desc&page=1</tt> action.
       #
       #   current_page?(action: 'process')
       #   # => false
       #
-      #   current_page?(controller: 'shop', action: 'checkout')
-      #   # => true
-      #
-      #   current_page?(controller: 'shop', action: 'checkout', order: 'asc')
-      #   # => false
-      #
       #   current_page?(action: 'checkout')
       #   # => true
       #
       #   current_page?(controller: 'library', action: 'checkout')
       #   # => false
       #
-      #   current_page?('http://www.example.com/shop/checkout')
-      #   # => true
-      #
-      #   current_page?('/shop/checkout')
+      #   current_page?(controller: 'shop', action: 'checkout')
       #   # => true
       #
-      # Let's say we're in the <tt>http://www.example.com/shop/checkout?order=desc&page=1</tt> action.
-      #
-      #   current_page?(action: 'process')
+      #   current_page?(controller: 'shop', action: 'checkout', order: 'asc')
       #   # => false
       #
-      #   current_page?(controller: 'shop', action: 'checkout')
-      #   # => true
-      #
       #   current_page?(controller: 'shop', action: 'checkout', order: 'desc', page: '1')
       #   # => true
       #
       #   current_page?(controller: 'shop', action: 'checkout', order: 'desc', page: '2')
       #   # => false
       #
-      #   current_page?(controller: 'shop', action: 'checkout', order: 'desc')
-      #   # => false
+      #   current_page?('http://www.example.com/shop/checkout')
+      #   # => true
       #
-      #   current_page?(action: 'checkout')
+      #   current_page?('/shop/checkout')
       #   # => true
       #
-      #   current_page?(controller: 'library', action: 'checkout')
-      #   # => false
+      #   current_page?('http://www.example.com/shop/checkout?order=desc&page=1')
+      #   # => true
       #
       # Let's say we're in the <tt>http://www.example.com/products</tt> action with method POST in case of invalid product.
       #
       #   current_page?(controller: 'product', action: 'index')
       #   # => false
       #
+      # We can also pass in the symbol arguments instead of strings.
+      #
       def current_page?(options)
         unless request
           raise "You cannot use helpers that need to determine the current " \
@@ -576,34 +569,6 @@ module ActionView
           html_options["data-method"] = method
         end
 
-        # Processes the +html_options+ hash, converting the boolean
-        # attributes from true/false form into the form required by
-        # HTML/XHTML. (An attribute is considered to be boolean if
-        # its name is listed in the given +bool_attrs+ array.)
-        #
-        # More specifically, for each boolean attribute in +html_options+
-        # given as:
-        #
-        #   "attr" => bool_value
-        #
-        # if the associated +bool_value+ evaluates to true, it is
-        # replaced with the attribute's name; otherwise the attribute is
-        # removed from the +html_options+ hash. (See the XHTML 1.0 spec,
-        # section 4.5 "Attribute Minimization" for more:
-        # http://www.w3.org/TR/xhtml1/#h-4.5)
-        #
-        # Returns the updated +html_options+ hash, which is also modified
-        # in place.
-        #
-        # Example:
-        #
-        #   convert_boolean_attributes!( html_options,
-        #                                %w( checked disabled readonly ) )
-        def convert_boolean_attributes!(html_options, bool_attrs)
-          bool_attrs.each { |x| html_options[x] = x if html_options.delete(x) }
-          html_options
-        end
-
         def token_tag(token=nil)
           if token != false && protect_against_forgery?
             token ||= form_authenticity_token
diff --git a/actionview/lib/action_view/layouts.rb b/actionview/lib/action_view/layouts.rb
index 0b5c0b9991..a74a5e05f3 100644
--- a/actionview/lib/action_view/layouts.rb
+++ b/actionview/lib/action_view/layouts.rb
@@ -228,7 +228,7 @@ module ActionView
         # set by the <tt>layout</tt> method.
         #
         # ==== Returns
-        # * <tt> Boolean</tt> - True if the action has a layout definition, false otherwise.
+        # * <tt>Boolean</tt> - True if the action has a layout definition, false otherwise.
         def _conditional_layout?
           return unless super
 
@@ -277,7 +277,7 @@ module ActionView
         remove_possible_method(:_layout)
 
         prefixes    = _implied_layout_name =~ /\blayouts/ ? [] : ["layouts"]
-        default_behavior = "lookup_context.find_all('#{_implied_layout_name}', #{prefixes.inspect}).first || super"
+        default_behavior = "lookup_context.find_all('#{_implied_layout_name}', #{prefixes.inspect}, false, [], { formats: formats }).first || super"
         name_clause = if name
           default_behavior
         else
@@ -316,7 +316,7 @@ module ActionView
         end
 
         self.class_eval <<-RUBY, __FILE__, __LINE__ + 1
-          def _layout
+          def _layout(formats)
             if _conditional_layout?
               #{layout_definition}
             else
@@ -372,7 +372,7 @@ module ActionView
     end
 
     # This will be overwritten by _write_layout_method
-    def _layout; end
+    def _layout(*); end
 
     # Determine the layout for a given name, taking into account the name type.
     #
@@ -382,8 +382,8 @@ module ActionView
       case name
       when String     then _normalize_layout(name)
       when Proc       then name
-      when true       then Proc.new { _default_layout(true)  }
-      when :default   then Proc.new { _default_layout(false) }
+      when true       then Proc.new { |formats| _default_layout(formats, true)  }
+      when :default   then Proc.new { |formats| _default_layout(formats, false) }
       when false, nil then nil
       else
         raise ArgumentError,
@@ -399,14 +399,15 @@ module ActionView
     # Optionally raises an exception if the layout could not be found.
     #
     # ==== Parameters
+    # * <tt>formats</tt> - The formats accepted to this layout
     # * <tt>require_layout</tt> - If set to true and layout is not found,
-    #   an ArgumentError exception is raised (defaults to false)
+    #   an +ArgumentError+ exception is raised (defaults to false)
     #
     # ==== Returns
     # * <tt>template</tt> - The template object for the default layout (or nil)
-    def _default_layout(require_layout = false)
+    def _default_layout(formats, require_layout = false)
       begin
-        value = _layout if action_has_layout?
+        value = _layout(formats) if action_has_layout?
       rescue NameError => e
         raise e, "Could not render layout: #{e.message}"
       end
diff --git a/actionview/lib/action_view/lookup_context.rb b/actionview/lib/action_view/lookup_context.rb
index 36855ec3d0..ec6edfaaa3 100644
--- a/actionview/lib/action_view/lookup_context.rb
+++ b/actionview/lib/action_view/lookup_context.rb
@@ -1,4 +1,4 @@
-require 'thread_safe'
+require 'concurrent'
 require 'active_support/core_ext/module/remove_method'
 require 'active_support/core_ext/module/attribute_accessors'
 require 'action_view/template/resolver'
@@ -6,10 +6,11 @@ require 'action_view/template/resolver'
 module ActionView
   # = Action View Lookup Context
   #
-  # LookupContext is the object responsible to hold all information required to lookup
-  # templates, i.e. view paths and details. The LookupContext is also responsible to
-  # generate a key, given to view paths, used in the resolver cache lookup. Since
-  # this key is generated just once during the request, it speeds up all cache accesses.
+  # <tt>LookupContext</tt> is the object responsible for holding all information
+  # required for looking up templates, i.e. view paths and details.
+  # <tt>LookupContext</tt> is also responsible for generating a key, given to
+  # view paths, used in the resolver cache lookup. Since this key is generated
+  # only once during the request, it speeds up all cache accesses.
   class LookupContext #:nodoc:
     attr_accessor :prefixes, :rendered_format
 
@@ -19,7 +20,7 @@ module ActionView
     mattr_accessor :registered_details
     self.registered_details = []
 
-    def self.register_detail(name, options = {}, &block)
+    def self.register_detail(name, &block)
       self.registered_details << name
       initialize = registered_details.map { |n| "@details[:#{n}] = details[:#{n}] || default_#{n}" }
 
@@ -54,14 +55,14 @@ module ActionView
     end
     register_detail(:formats) { ActionView::Base.default_formats || [:html, :text, :js, :css,  :xml, :json] }
     register_detail(:variants) { [] }
-    register_detail(:handlers){ Template::Handlers.extensions }
+    register_detail(:handlers) { Template::Handlers.extensions }
 
     class DetailsKey #:nodoc:
       alias :eql? :equal?
       alias :object_hash :hash
 
       attr_reader :hash
-      @details_keys = ThreadSafe::Cache.new
+      @details_keys = Concurrent::Map.new
 
       def self.get(details)
         if details[:formats]
@@ -126,7 +127,7 @@ module ActionView
         @view_paths.find_all(*args_for_lookup(name, prefixes, partial, keys, options))
       end
 
-      def exists?(name, prefixes = [], partial = false, keys = [], options = {})
+      def exists?(name, prefixes = [], partial = false, keys = [], **options)
         @view_paths.exists?(*args_for_lookup(name, prefixes, partial, keys, options))
       end
       alias :template_exists? :exists?
@@ -172,13 +173,13 @@ module ActionView
       # name instead of the prefix.
       def normalize_name(name, prefixes) #:nodoc:
         prefixes = prefixes.presence
-        parts    = name.to_s.split('/')
+        parts    = name.to_s.split('/'.freeze)
         parts.shift if parts.first.empty?
         name     = parts.pop
 
         return name, prefixes || [""] if parts.empty?
 
-        parts    = parts.join('/')
+        parts    = parts.join('/'.freeze)
         prefixes = prefixes ? prefixes.map { |p| "#{p}/#{parts}" } : [parts]
 
         return name, prefixes
@@ -203,7 +204,7 @@ module ActionView
     # add :html as fallback to :js.
     def formats=(values)
       if values
-        values.concat(default_formats) if values.delete "*/*"
+        values.concat(default_formats) if values.delete "*/*".freeze
         if values == [:js]
           values << :html
           @html_fallback_for_js = true
@@ -228,21 +229,5 @@ module ActionView
 
       super(default_locale)
     end
-
-    # Uses the first format in the formats array for layout lookup.
-    def with_layout_format
-      if formats.size == 1
-        yield
-      else
-        old_formats = formats
-        _set_detail(:formats, formats[0,1])
-
-        begin
-          yield
-        ensure
-          _set_detail(:formats, old_formats)
-        end
-      end
-    end
   end
 end
diff --git a/actionview/lib/action_view/model_naming.rb b/actionview/lib/action_view/model_naming.rb
index d42e436b17..b6ed13424e 100644
--- a/actionview/lib/action_view/model_naming.rb
+++ b/actionview/lib/action_view/model_naming.rb
@@ -1,5 +1,5 @@
 module ActionView
-  module ModelNaming
+  module ModelNaming #:nodoc:
     # Converts the given object to an ActiveModel compliant one.
     def convert_to_model(object)
       object.respond_to?(:to_model) ? object.to_model : object
diff --git a/actionview/lib/action_view/path_set.rb b/actionview/lib/action_view/path_set.rb
index 91ee2ea8f5..7a88f6bc50 100644
--- a/actionview/lib/action_view/path_set.rb
+++ b/actionview/lib/action_view/path_set.rb
@@ -61,6 +61,15 @@ module ActionView #:nodoc:
       find_all(path, prefixes, *args).any?
     end
 
+    def find_all_with_query(query) # :nodoc:
+      paths.each do |resolver|
+        templates = resolver.find_all_with_query(query)
+        return templates unless templates.empty?
+      end
+
+      []
+    end
+
     private
 
     def typecast(paths)
diff --git a/actionview/lib/action_view/railtie.rb b/actionview/lib/action_view/railtie.rb
index 81f9c40b85..e829d86c99 100644
--- a/actionview/lib/action_view/railtie.rb
+++ b/actionview/lib/action_view/railtie.rb
@@ -36,14 +36,30 @@ module ActionView
       end
     end
 
+    initializer "action_view.collection_caching" do |app|
+      ActiveSupport.on_load(:action_controller) do
+        PartialRenderer.collection_cache = app.config.action_controller.cache_store
+      end
+    end
+
+    initializer "action_view.per_request_digest_cache" do |app|
+      ActiveSupport.on_load(:action_view) do
+        if app.config.consider_all_requests_local
+          app.middleware.use ActionView::Digestor::PerRequestDigestCacheExpiry
+        end
+      end
+    end
+
     initializer "action_view.setup_action_pack" do |app|
       ActiveSupport.on_load(:action_controller) do
-        ActionView::RoutingUrlFor.send(:include, ActionDispatch::Routing::UrlFor)
+        ActionView::RoutingUrlFor.include(ActionDispatch::Routing::UrlFor)
       end
     end
 
-    rake_tasks do
-      load "action_view/tasks/dependencies.rake"
+    rake_tasks do |app|
+      unless app.config.api_only
+        load "action_view/tasks/dependencies.rake"
+      end
     end
   end
 end
diff --git a/actionview/lib/action_view/record_identifier.rb b/actionview/lib/action_view/record_identifier.rb
index c8484bed34..4b44eb5520 100644
--- a/actionview/lib/action_view/record_identifier.rb
+++ b/actionview/lib/action_view/record_identifier.rb
@@ -11,7 +11,7 @@ module ActionView
   #     <%= post.body %>
   #   <% end %>
   #
-  # When +post+ is a new, unsaved ActiveRecord::Base intance, the resulting HTML
+  # When +post+ is a new, unsaved ActiveRecord::Base instance, the resulting HTML
   # is:
   #
   #    <div id="new_post" class="post">
@@ -103,7 +103,7 @@ module ActionView
     # make sure yourself that your dom ids are valid, in case you overwrite this method.
     def record_key_for_dom_id(record)
       key = convert_to_model(record).to_key
-      key ? key.join('_') : key
+      key ? key.join(JOIN) : key
     end
   end
 end
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 6c3015180a..39c8658ffe 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -1,4 +1,5 @@
-require 'thread_safe'
+require 'action_view/renderer/partial_renderer/collection_caching'
+require 'concurrent'
 
 module ActionView
   class PartialIteration
@@ -153,23 +154,23 @@ module ActionView
   # specified globally for the entire action, but they work in a similar fashion. Imagine a list with two types
   # of users:
   #
-  #   <%# app/views/users/index.html.erb &>
+  #   <%# app/views/users/index.html.erb %>
   #   Here's the administrator:
   #   <%= render partial: "user", layout: "administrator", locals: { user: administrator } %>
   #
   #   Here's the editor:
   #   <%= render partial: "user", layout: "editor", locals: { user: editor } %>
   #
-  #   <%# app/views/users/_user.html.erb &>
+  #   <%# app/views/users/_user.html.erb %>
   #   Name: <%= user.name %>
   #
-  #   <%# app/views/users/_administrator.html.erb &>
+  #   <%# app/views/users/_administrator.html.erb %>
   #   <div id="administrator">
   #     Budget: $<%= user.budget %>
   #     <%= yield %>
   #   </div>
   #
-  #   <%# app/views/users/_editor.html.erb &>
+  #   <%# app/views/users/_editor.html.erb %>
   #   <div id="editor">
   #     Deadline: <%= user.deadline %>
   #     <%= yield %>
@@ -232,7 +233,7 @@ module ActionView
   #
   # You can also apply a layout to a block within any template:
   #
-  #   <%# app/views/users/_chief.html.erb &>
+  #   <%# app/views/users/_chief.html.erb %>
   #   <%= render(layout: "administrator", locals: { user: chief }) do %>
   #     Title: <%= chief.title %>
   #   <% end %>
@@ -249,13 +250,13 @@ module ActionView
   # If you pass arguments to "yield" then this will be passed to the block. One way to use this is to pass
   # an array to layout and treat it as an enumerable.
   #
-  #   <%# app/views/users/_user.html.erb &>
+  #   <%# app/views/users/_user.html.erb %>
   #   <div class="user">
   #     Budget: $<%= user.budget %>
   #     <%= yield user %>
   #   </div>
   #
-  #   <%# app/views/users/index.html.erb &>
+  #   <%# app/views/users/index.html.erb %>
   #   <%= render layout: @users do |user| %>
   #     Title: <%= user.title %>
   #   <% end %>
@@ -264,14 +265,14 @@ module ActionView
   #
   # You can also yield multiple times in one layout and use block arguments to differentiate the sections.
   #
-  #   <%# app/views/users/_user.html.erb &>
+  #   <%# app/views/users/_user.html.erb %>
   #   <div class="user">
   #     <%= yield user, :header %>
   #     Budget: $<%= user.budget %>
   #     <%= yield user, :footer %>
   #   </div>
   #
-  #   <%# app/views/users/index.html.erb &>
+  #   <%# app/views/users/index.html.erb %>
   #   <%= render layout: @users do |user, section| %>
   #     <%- case section when :header -%>
   #       Title: <%= user.title %>
@@ -280,8 +281,10 @@ module ActionView
   #     <%- end -%>
   #   <% end %>
   class PartialRenderer < AbstractRenderer
-    PREFIXED_PARTIAL_NAMES = ThreadSafe::Cache.new do |h, k|
-      h[k] = ThreadSafe::Cache.new
+    include CollectionCaching
+
+    PREFIXED_PARTIAL_NAMES = Concurrent::Map.new do |h, k|
+      h[k] = Concurrent::Map.new
     end
 
     def initialize(*)
@@ -321,8 +324,9 @@ module ActionView
         spacer = find_template(@options[:spacer_template], @locals.keys).render(@view, @locals)
       end
 
-      result = @template ? collection_with_template : collection_without_template
-      result.join(spacer).html_safe
+      cache_collection_render do
+        @template ? collection_with_template : collection_without_template
+      end.join(spacer).html_safe
     end
 
     def render_partial
@@ -334,7 +338,7 @@ module ActionView
       end
 
       object ||= locals[as]
-      locals[as] = object
+      locals[as] = object if @has_object
 
       content = @template.render(view, locals) do |*name|
         view._layout_for(*name, &block)
@@ -344,8 +348,6 @@ module ActionView
       content
     end
 
-    private
-
     # Sets up instance variables needed for rendering a partial. This method
     # finds the options and details and extracts them. The method also contains
     # logic that handles the type of object passed in as the partial.
@@ -518,8 +520,8 @@ module ActionView
 
     def retrieve_variable(path, as)
       variable = as || begin
-        base = path[-1] == "/" ? "" : File.basename(path)
-        raise_invalid_identifier(path) unless base =~ /\A_?([a-z]\w*)(\.\w+)*\z/
+        base = path[-1] == "/".freeze ? "".freeze : File.basename(path)
+        raise_invalid_identifier(path) unless base =~ /\A_?(.*)(?:\.\w+)*\z/
         $1.to_sym
       end
       if @collection
@@ -530,8 +532,7 @@ module ActionView
     end
 
     IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " +
-                               "make sure your partial name starts with underscore, " +
-                               "and is followed by any combination of letters, numbers and underscores."
+                               "make sure your partial name starts with underscore."
 
     OPTION_AS_ERROR_MESSAGE  = "The value (%s) of the option `as` is not a valid Ruby identifier; " +
                                "make sure it starts with lowercase letter, " +
diff --git a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
new file mode 100644
index 0000000000..1147963882
--- /dev/null
+++ b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
@@ -0,0 +1,70 @@
+require 'active_support/core_ext/object/try'
+
+module ActionView
+  module CollectionCaching # :nodoc:
+    extend ActiveSupport::Concern
+
+    included do
+      # Fallback cache store if Action View is used without Rails.
+      # Otherwise overridden in Railtie to use Rails.cache.
+      mattr_accessor(:collection_cache) { ActiveSupport::Cache::MemoryStore.new }
+    end
+
+    private
+      def cache_collection_render
+        return yield unless cache_collection?
+
+        keyed_collection = collection_by_cache_keys
+        partial_cache = collection_cache.read_multi(*keyed_collection.keys)
+
+        @collection = keyed_collection.reject { |key, _| partial_cache.key?(key) }.values
+        rendered_partials = @collection.any? ? yield.dup : []
+
+        fetch_or_cache_partial(partial_cache, order_by: keyed_collection.each_key) do
+          rendered_partials.shift
+        end
+      end
+
+      def cache_collection?
+        @options.fetch(:cache, automatic_cache_eligible?)
+      end
+
+      def automatic_cache_eligible?
+        single_template_render? && !callable_cache_key? &&
+          @template.eligible_for_collection_caching?(as: @options[:as])
+      end
+
+      def single_template_render?
+        @template # Template is only set when a collection renders one template.
+      end
+
+      def callable_cache_key?
+        @options[:cache].respond_to?(:call)
+      end
+
+      def collection_by_cache_keys
+        seed = callable_cache_key? ? @options[:cache] : ->(i) { i }
+
+        @collection.each_with_object({}) do |item, hash|
+          hash[expanded_cache_key(seed.call(item))] = item
+        end
+      end
+
+      def expanded_cache_key(key)
+        key = @view.fragment_cache_key(@view.cache_fragment_name(key, virtual_path: @template.virtual_path))
+        key.frozen? ? key.dup : key # #read_multi & #write may require mutability, Dalli 2.6.0.
+      end
+
+      def fetch_or_cache_partial(cached_partials, order_by:)
+        cache_options = @options[:cache_options] || @locals[:cache_options] || {}
+
+        order_by.map do |key|
+          cached_partials.fetch(key) do
+            yield.tap do |rendered_partial|
+              collection_cache.write(key, rendered_partial, cache_options)
+            end
+          end
+        end
+      end
+  end
+end
diff --git a/actionview/lib/action_view/renderer/renderer.rb b/actionview/lib/action_view/renderer/renderer.rb
index 964b18337e..1bee35d80d 100644
--- a/actionview/lib/action_view/renderer/renderer.rb
+++ b/actionview/lib/action_view/renderer/renderer.rb
@@ -37,7 +37,7 @@ module ActionView
       end
     end
 
-    # Direct accessor to template rendering.
+    # Direct access to template rendering.
     def render_template(context, options) #:nodoc:
       TemplateRenderer.new(@lookup_context).render(context, options)
     end
diff --git a/actionview/lib/action_view/renderer/streaming_template_renderer.rb b/actionview/lib/action_view/renderer/streaming_template_renderer.rb
index 3ab2cd36fc..f38e2764d0 100644
--- a/actionview/lib/action_view/renderer/streaming_template_renderer.rb
+++ b/actionview/lib/action_view/renderer/streaming_template_renderer.rb
@@ -47,7 +47,7 @@ module ActionView
       return [super] unless layout_name && template.supports_streaming?
 
       locals ||= {}
-      layout   = layout_name && find_layout(layout_name, locals.keys)
+      layout   = layout_name && find_layout(layout_name, locals.keys, [formats.first])
 
       Body.new do |buffer|
         delayed_render(buffer, template, layout, @view, locals)
diff --git a/actionview/lib/action_view/renderer/template_renderer.rb b/actionview/lib/action_view/renderer/template_renderer.rb
index cd21d7ab47..75217e1630 100644
--- a/actionview/lib/action_view/renderer/template_renderer.rb
+++ b/actionview/lib/action_view/renderer/template_renderer.rb
@@ -40,7 +40,7 @@ module ActionView
           find_template(options[:template], options[:prefixes], false, keys, @details)
         end
       else
-        raise ArgumentError, "You invoked render but did not give any of :partial, :template, :inline, :file, :plain, :text or :body option."
+        raise ArgumentError, "You invoked render but did not give any of :partial, :template, :inline, :file, :plain, :html, :text or :body option."
       end
     end
 
@@ -57,7 +57,7 @@ module ActionView
     end
 
     def render_with_layout(path, locals) #:nodoc:
-      layout  = path && find_layout(path, locals.keys)
+      layout  = path && find_layout(path, locals.keys, [formats.first])
       content = yield(layout)
 
       if layout
@@ -72,27 +72,28 @@ module ActionView
     # This is the method which actually finds the layout using details in the lookup
     # context object. If no layout is found, it checks if at least a layout with
     # the given name exists across all details before raising the error.
-    def find_layout(layout, keys)
-      with_layout_format { resolve_layout(layout, keys) }
+    def find_layout(layout, keys, formats)
+      resolve_layout(layout, keys, formats)
     end
 
-    def resolve_layout(layout, keys)
+    def resolve_layout(layout, keys, formats)
+      details = @details.dup
+      details[:formats] = formats
+
       case layout
       when String
         begin
           if layout =~ /^\//
-            with_fallbacks { find_template(layout, nil, false, keys, @details) }
+            with_fallbacks { find_template(layout, nil, false, keys, details) }
           else
-            find_template(layout, nil, false, keys, @details)
+            find_template(layout, nil, false, keys, details)
           end
         rescue ActionView::MissingTemplate
           all_details = @details.merge(:formats => @lookup_context.default_formats)
           raise unless template_exists?(layout, nil, false, keys, all_details)
         end
       when Proc
-        resolve_layout(layout.call, keys)
-      when FalseClass
-        nil
+        resolve_layout(layout.call(formats), keys, formats)
       else
         layout
       end
diff --git a/actionview/lib/action_view/rendering.rb b/actionview/lib/action_view/rendering.rb
index abd3b77c67..8604637da2 100644
--- a/actionview/lib/action_view/rendering.rb
+++ b/actionview/lib/action_view/rendering.rb
@@ -59,7 +59,7 @@ module ActionView
       @_view_context_class ||= self.class.view_context_class
     end
 
-    # An instance of a view class. The default view class is ActionView::Base
+    # An instance of a view class. The default view class is ActionView::Base.
     #
     # The view class must have the following methods:
     # View.new[lookup_context, assigns, controller]
@@ -92,16 +92,19 @@ module ActionView
       # Find and render a template based on the options given.
       # :api: private
       def _render_template(options) #:nodoc:
-        variant = options[:variant]
+        variant = options.delete(:variant)
+        assigns = options.delete(:assigns)
+        context = view_context
 
+        context.assign assigns if assigns
         lookup_context.rendered_format = nil if options[:formats]
         lookup_context.variants = variant if variant
 
-        view_renderer.render(view_context, options)
+        view_renderer.render(context, options)
       end
 
-      # Assign the rendered format to lookup context.
-      def _process_format(format, options = {}) #:nodoc:
+      # Assign the rendered format to look up context.
+      def _process_format(format) #:nodoc:
         super
         lookup_context.formats = [format.to_sym]
         lookup_context.rendered_format = lookup_context.formats.first
diff --git a/actionview/lib/action_view/routing_url_for.rb b/actionview/lib/action_view/routing_url_for.rb
index f281333a41..45e78d1ad9 100644
--- a/actionview/lib/action_view/routing_url_for.rb
+++ b/actionview/lib/action_view/routing_url_for.rb
@@ -32,7 +32,7 @@ module ActionView
     #
     # ==== Examples
     #   <%= url_for(action: 'index') %>
-    #   # => /blog/
+    #   # => /blogs/
     #
     #   <%= url_for(action: 'find', controller: 'books') %>
     #   # => /books/find
@@ -84,21 +84,24 @@ module ActionView
       when Hash
         options = options.symbolize_keys
         unless options.key?(:only_path)
-          if options[:host].nil?
-            options[:only_path] = _generate_paths_by_default
-          else
-            options[:only_path] = false
-          end
+          options[:only_path] = only_path?(options[:host])
+        end
+
+        super(options)
+      when ActionController::Parameters
+        unless options.key?(:only_path)
+          options[:only_path] = only_path?(options[:host])
         end
 
         super(options)
       when :back
         _back_url
       when Array
+        components = options.dup
         if _generate_paths_by_default
-          polymorphic_path(options, options.extract_options!)
+          polymorphic_path(components, components.extract_options!)
         else
-          polymorphic_url(options, options.extract_options!)
+          polymorphic_url(components, components.extract_options!)
         end
       else
         method = _generate_paths_by_default ? :path : :url
@@ -130,5 +133,15 @@ module ActionView
         controller.optimize_routes_generation? : super
     end
     protected :optimize_routes_generation?
+
+    private
+
+      def _generate_paths_by_default
+        true
+      end
+
+      def only_path?(host)
+        _generate_paths_by_default unless host
+      end
   end
 end
diff --git a/actionview/lib/action_view/tasks/dependencies.rake b/actionview/lib/action_view/tasks/dependencies.rake
index b39f7d583b..f394c319c1 100644
--- a/actionview/lib/action_view/tasks/dependencies.rake
+++ b/actionview/lib/action_view/tasks/dependencies.rake
@@ -2,20 +2,22 @@ namespace :cache_digests do
   desc 'Lookup nested dependencies for TEMPLATE (like messages/show or comments/_comment.html)'
   task :nested_dependencies => :environment do
     abort 'You must provide TEMPLATE for the task to run' unless ENV['TEMPLATE'].present?
-    puts JSON.pretty_generate ActionView::Digestor.new(name: template_name, finder: finder).nested_dependencies
+    puts JSON.pretty_generate ActionView::Digestor.new(name: CacheDigests.template_name, finder: CacheDigests.finder).nested_dependencies
   end
 
   desc 'Lookup first-level dependencies for TEMPLATE (like messages/show or comments/_comment.html)'
   task :dependencies => :environment do
     abort 'You must provide TEMPLATE for the task to run' unless ENV['TEMPLATE'].present?
-    puts JSON.pretty_generate ActionView::Digestor.new(name: template_name, finder: finder).dependencies
+    puts JSON.pretty_generate ActionView::Digestor.new(name: CacheDigests.template_name, finder: CacheDigests.finder).dependencies
   end
 
-  def template_name
-    ENV['TEMPLATE'].split('.', 2).first
-  end
+  class CacheDigests
+    def self.template_name
+      ENV['TEMPLATE'].split('.', 2).first
+    end
 
-  def finder
-    ApplicationController.new.lookup_context
+    def self.finder
+      ApplicationController.new.lookup_context
+    end
   end
 end
diff --git a/actionview/lib/action_view/template.rb b/actionview/lib/action_view/template.rb
index 6b61378a1f..0ed208f27e 100644
--- a/actionview/lib/action_view/template.rb
+++ b/actionview/lib/action_view/template.rb
@@ -87,6 +87,19 @@ module ActionView
     #       expected_encoding
     #     )
 
+    ##
+    # :method: local_assigns
+    #
+    # Returns a hash with the defined local variables.
+    #
+    # Given this sub template rendering:
+    #
+    #   <%= render "shared/header", { headline: "Welcome", person: person } %>
+    #
+    # You can use +local_assigns+ in the sub templates to access the local variables:
+    #
+    #   local_assigns[:headline] # => "Welcome"
+
     eager_autoload do
       autoload :Error
       autoload :Handlers
@@ -103,7 +116,7 @@ module ActionView
 
     # This finalizer is needed (and exactly with a proc inside another proc)
     # otherwise templates leak in development.
-    Finalizer = proc do |method_name, mod|
+    Finalizer = proc do |method_name, mod| # :nodoc:
       proc do
         mod.module_eval do
           remove_possible_method method_name
@@ -117,6 +130,7 @@ module ActionView
       @source            = source
       @identifier        = identifier
       @handler           = handler
+      @cache_name        = extract_resource_cache_name
       @compiled          = false
       @original_encoding = nil
       @locals            = details[:locals] || []
@@ -127,7 +141,7 @@ module ActionView
       @compile_mutex     = Mutex.new
     end
 
-    # Returns if the underlying handler supports streaming. If so,
+    # Returns whether the underlying handler supports streaming. If so,
     # a streaming buffer *may* be passed when it start rendering.
     def supports_streaming?
       handler.respond_to?(:supports_streaming?) && handler.supports_streaming?
@@ -140,7 +154,7 @@ module ActionView
     # we use a bang in this instrumentation because you don't want to
     # consume this in production. This is only slow if it's being listened to.
     def render(view, locals, buffer=nil, &block)
-      instrument("!render_template") do
+      instrument("!render_template".freeze) do
         compile!(view)
         view.send(method_name, locals, buffer, &block)
       end
@@ -152,6 +166,10 @@ module ActionView
       @type ||= Types[@formats.first] if @formats.first
     end
 
+    def eligible_for_collection_caching?(as: nil)
+      @cache_name == (as || inferred_cache_name).to_s
+    end
+
     # Receives a view object and return a template similar to self by using @virtual_path.
     #
     # This method is useful if you have a template object but it does not contain its source
@@ -172,7 +190,7 @@ module ActionView
     end
 
     def inspect
-      @inspect ||= defined?(Rails.root) ? identifier.sub("#{Rails.root}/", '') : identifier
+      @inspect ||= defined?(Rails.root) ? identifier.sub("#{Rails.root}/", ''.freeze) : identifier
     end
 
     # This method is responsible for properly setting the encoding of the
@@ -319,18 +337,41 @@ module ActionView
       def method_name #:nodoc:
         @method_name ||= begin
           m = "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}"
-          m.tr!('-', '_')
+          m.tr!('-'.freeze, '_'.freeze)
           m
         end
       end
 
       def identifier_method_name #:nodoc:
-        inspect.tr('^a-z_', '_')
+        inspect.tr('^a-z_'.freeze, '_'.freeze)
       end
 
       def instrument(action, &block)
         payload = { virtual_path: @virtual_path, identifier: @identifier }
-        ActiveSupport::Notifications.instrument("#{action}.action_view", payload, &block)
+        case action
+        when "!render_template".freeze
+          ActiveSupport::Notifications.instrument("!render_template.action_view".freeze, payload, &block)
+        else
+          ActiveSupport::Notifications.instrument("#{action}.action_view".freeze, payload, &block)
+        end
+      end
+
+      EXPLICIT_COLLECTION = /# Template Collection: (?<resource_name>\w+)/
+
+      def extract_resource_cache_name
+        if match = @source.match(EXPLICIT_COLLECTION) || resource_cache_call_match
+          match[:resource_name]
+        end
+      end
+
+      def resource_cache_call_match
+        if @handler.respond_to?(:resource_cache_call_pattern)
+          @source.match(@handler.resource_cache_call_pattern)
+        end
+      end
+
+      def inferred_cache_name
+        @inferred_cache_name ||= @virtual_path.split('/'.freeze).last.sub('_'.freeze, ''.freeze)
       end
   end
 end
diff --git a/actionview/lib/action_view/template/handlers/erb.rb b/actionview/lib/action_view/template/handlers/erb.rb
index 85a100ed4c..1f8459c24b 100644
--- a/actionview/lib/action_view/template/handlers/erb.rb
+++ b/actionview/lib/action_view/template/handlers/erb.rb
@@ -123,6 +123,31 @@ module ActionView
           ).src
         end
 
+        # Returns Regexp to extract a cached resource's name from a cache call at the
+        # first line of a template.
+        # The extracted cache name is captured as :resource_name.
+        #
+        #   <% cache notification do %> # => notification
+        #
+        # The pattern should support templates with a beginning comment:
+        #
+        #   <%# Still extractable even though there's a comment %>
+        #   <% cache notification do %> # => notification
+        #
+        # But fail to extract a name if a resource association is cached.
+        #
+        #   <% cache notification.event do %> # => nil
+        def resource_cache_call_pattern
+          /\A
+            (?:<%\#.*%>)*                 # optional initial comment
+            \s*                           # followed by optional spaces or newlines
+            <%\s*cache[\(\s]              # followed by an ERB call to cache
+            \s*                           # followed by optional spaces or newlines
+            (?<resource_name>\w+)         # capture the cache call argument as :resource_name
+            [\s\)]                        # followed by a space or close paren
+          /xm
+        end
+
       private
 
         def valid_encoding(string, encoding)
diff --git a/actionview/lib/action_view/template/handlers/raw.rb b/actionview/lib/action_view/template/handlers/raw.rb
index 397c86014a..b08fb0870f 100644
--- a/actionview/lib/action_view/template/handlers/raw.rb
+++ b/actionview/lib/action_view/template/handlers/raw.rb
@@ -2,7 +2,7 @@ module ActionView
   module Template::Handlers
     class Raw
       def call(template)
-        escaped = template.source.gsub(/:/, '\:')
+        escaped = template.source.gsub(':'.freeze, '\:'.freeze)
 
         '%q:' + escaped + ':;'
       end
diff --git a/actionview/lib/action_view/template/resolver.rb b/actionview/lib/action_view/template/resolver.rb
index bc0db330ea..7859c58b43 100644
--- a/actionview/lib/action_view/template/resolver.rb
+++ b/actionview/lib/action_view/template/resolver.rb
@@ -3,7 +3,7 @@ require "active_support/core_ext/class"
 require "active_support/core_ext/module/attribute_accessors"
 require "action_view/template"
 require "thread"
-require "thread_safe"
+require "concurrent"
 
 module ActionView
   # = Action View Resolver
@@ -35,7 +35,7 @@ module ActionView
 
     # Threadsafe template cache
     class Cache #:nodoc:
-      class SmallCache < ThreadSafe::Cache
+      class SmallCache < Concurrent::Map
         def initialize(options = {})
           super(options.merge(:initial_capacity => 2))
         end
@@ -52,6 +52,7 @@ module ActionView
 
       def initialize
         @data = SmallCache.new(&KEY_BLOCK)
+        @query_cache = SmallCache.new
       end
 
       # Cache the templates returned by the block
@@ -70,8 +71,17 @@ module ActionView
         end
       end
 
+      def cache_query(query) # :nodoc:
+        if Resolver.caching?
+          @query_cache[query] ||= canonical_no_templates(yield)
+        else
+          yield
+        end
+      end
+
       def clear
         @data.clear
+        @query_cache.clear
       end
 
       private
@@ -116,6 +126,10 @@ module ActionView
       end
     end
 
+    def find_all_with_query(query) # :nodoc:
+      @cache.cache_query(query) { find_template_paths(File.join(@path, query)) }
+    end
+
   private
 
     delegate :caching?, to: :class
@@ -181,9 +195,9 @@ module ActionView
     def query(path, details, formats)
       query = build_query(path, details)
 
-      template_paths = find_template_paths query
+      template_paths = find_template_paths(query)
 
-      template_paths.map { |template|
+      template_paths.map do |template|
         handler, format, variant = extract_handler_and_format_and_variant(template, formats)
         contents = File.binread(template)
 
@@ -193,36 +207,36 @@ module ActionView
           :variant      => variant,
           :updated_at   => mtime(template)
         )
-      }
+      end
     end
 
     def find_template_paths(query)
-      Dir[query].reject { |filename|
+      Dir[query].reject do |filename|
         File.directory?(filename) ||
           # deals with case-insensitive file systems.
           !File.fnmatch(query, filename, File::FNM_EXTGLOB)
-      }
+      end
     end
 
     # Helper for building query glob string based on resolver's pattern.
     def build_query(path, details)
       query = @pattern.dup
 
-      prefix = path.prefix.empty? ? "" : "#{escape_entry(path.prefix)}\\1"
-      query.gsub!(/\:prefix(\/)?/, prefix)
+      prefix = path.prefix.empty? ? '' : "#{escape_entry(path.prefix)}\\1"
+      query.gsub!(/:prefix(\/)?/, prefix)
 
       partial = escape_entry(path.partial? ? "_#{path.name}" : path.name)
-      query.gsub!(/\:action/, partial)
+      query.gsub!(/:action/, partial)
 
       details.each do |ext, variants|
-        query.gsub!(/\:#{ext}/, "{#{variants.compact.uniq.join(',')}}")
+        query.gsub!(/:#{ext}/, "{#{variants.compact.uniq.join(',')}}")
       end
 
       File.expand_path(query, @path)
     end
 
     def escape_entry(entry)
-      entry.gsub(/[*?{}\[\]]/, '\\\\\\&')
+      entry.gsub(/[*?{}\[\]]/, '\\\\\\&'.freeze)
     end
 
     # Returns the file mtime from the filesystem.
@@ -234,7 +248,7 @@ module ActionView
     # from the path, or the handler, we should return the array of formats given
     # to the resolver.
     def extract_handler_and_format_and_variant(path, default_formats)
-      pieces = File.basename(path).split(".")
+      pieces = File.basename(path).split('.'.freeze)
       pieces.shift
 
       extension = pieces.pop
@@ -270,7 +284,7 @@ module ActionView
   #
   #   ActionController::Base.view_paths = FileSystemResolver.new(
   #     Rails.root.join("app/views"),
-  #     ":prefix{/:locale}/:action{.:formats,}{+:variants,}{.:handlers,}"
+  #     ":prefix/:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}",
   #   )
   #
   # ==== Pattern format and variables
diff --git a/actionview/lib/action_view/test_case.rb b/actionview/lib/action_view/test_case.rb
index 812b011bd7..f6b5696a13 100644
--- a/actionview/lib/action_view/test_case.rb
+++ b/actionview/lib/action_view/test_case.rb
@@ -24,8 +24,8 @@ module ActionView
       def initialize
         super
         self.class.controller_path = ""
-        @request = ActionController::TestRequest.new
-        @response = ActionController::TestResponse.new
+        @request = ActionController::TestRequest.create
+        @response = ActionDispatch::TestResponse.new
 
         @request.env.delete('PATH_INFO')
         @params = {}
@@ -204,7 +204,7 @@ module ActionView
       def view
         @view ||= begin
           view = @controller.view_context
-          view.singleton_class.send :include, _helpers
+          view.singleton_class.include(_helpers)
           view.extend(Locals)
           view.rendered_views = self.rendered_views
           view.output_buffer = self.output_buffer
@@ -263,9 +263,15 @@ module ActionView
       end
 
       def method_missing(selector, *args)
-        if @controller.respond_to?(:_routes) &&
-          ( @controller._routes.named_routes.route_defined?(selector) ||
-            @controller._routes.mounted_helpers.method_defined?(selector) )
+        begin
+          routes = @controller.respond_to?(:_routes) && @controller._routes
+        rescue
+          # Dont call routes, if there is an error on _routes call
+        end
+
+        if routes &&
+           ( routes.named_routes.route_defined?(selector) ||
+             routes.mounted_helpers.method_defined?(selector) )
           @controller.__send__(selector, *args)
         else
           super
diff --git a/actionview/lib/action_view/view_paths.rb b/actionview/lib/action_view/view_paths.rb
index 492f67f45d..37722013ce 100644
--- a/actionview/lib/action_view/view_paths.rb
+++ b/actionview/lib/action_view/view_paths.rb
@@ -36,9 +36,9 @@ module ActionView
       self.class._prefixes
     end
 
-    # LookupContext is the object responsible to hold all information required to lookup
-    # templates, i.e. view paths and details. Check ActionView::LookupContext for more
-    # information.
+    # <tt>LookupContext</tt> is the object responsible for holding all
+    # information required for looking up templates, i.e. view paths and
+    # details. Check <tt>ActionView::LookupContext</tt> for more information.
     def lookup_context
       @_lookup_context ||=
         ActionView::LookupContext.new(self.class._view_paths, details_for_lookup, _prefixes)
diff --git a/actionview/test/abstract_unit.rb b/actionview/test/abstract_unit.rb
index 4aa56f60f7..2354e91822 100644
--- a/actionview/test/abstract_unit.rb
+++ b/actionview/test/abstract_unit.rb
@@ -16,6 +16,7 @@ silence_warnings do
 end
 
 require 'active_support/testing/autorun'
+require 'active_support/testing/method_call_assertions'
 require 'action_controller'
 require 'action_view'
 require 'action_view/testing/resolvers'
@@ -49,20 +50,6 @@ I18n.backend.store_translations 'pt-BR', {}
 ORIGINAL_LOCALES = I18n.available_locales.map(&:to_s).sort
 
 FIXTURE_LOAD_PATH = File.join(File.dirname(__FILE__), 'fixtures')
-FIXTURES = Pathname.new(FIXTURE_LOAD_PATH)
-
-module RackTestUtils
-  def body_to_string(body)
-    if body.respond_to?(:each)
-      str = ""
-      body.each {|s| str << s }
-      str
-    else
-      body
-    end
-  end
-  extend self
-end
 
 module RenderERBUtils
   def view
@@ -161,13 +148,12 @@ class ActionDispatch::IntegrationTest < ActiveSupport::TestCase
 
   def self.build_app(routes = nil)
     RoutedRackApp.new(routes || ActionDispatch::Routing::RouteSet.new) do |middleware|
-      middleware.use "ActionDispatch::ShowExceptions", ActionDispatch::PublicExceptions.new("#{FIXTURE_LOAD_PATH}/public")
-      middleware.use "ActionDispatch::DebugExceptions"
-      middleware.use "ActionDispatch::Callbacks"
-      middleware.use "ActionDispatch::ParamsParser"
-      middleware.use "ActionDispatch::Cookies"
-      middleware.use "ActionDispatch::Flash"
-      middleware.use "Rack::Head"
+      middleware.use ActionDispatch::ShowExceptions, ActionDispatch::PublicExceptions.new("#{FIXTURE_LOAD_PATH}/public")
+      middleware.use ActionDispatch::DebugExceptions
+      middleware.use ActionDispatch::Callbacks
+      middleware.use ActionDispatch::Cookies
+      middleware.use ActionDispatch::Flash
+      middleware.use Rack::Head
       yield(middleware) if block_given?
     end
   end
@@ -225,50 +211,7 @@ class ActionDispatch::IntegrationTest < ActiveSupport::TestCase
   end
 end
 
-# Temporary base class
-class Rack::TestCase < ActionDispatch::IntegrationTest
-  def self.testing(klass = nil)
-    if klass
-      @testing = "/#{klass.name.underscore}".sub!(/_controller$/, '')
-    else
-      @testing
-    end
-  end
-
-  def get(thing, *args)
-    if thing.is_a?(Symbol)
-      super("#{self.class.testing}/#{thing}", *args)
-    else
-      super
-    end
-  end
-
-  def assert_body(body)
-    assert_equal body, Array(response.body).join
-  end
-
-  def assert_status(code)
-    assert_equal code, response.status
-  end
-
-  def assert_response(body, status = 200, headers = {})
-    assert_body body
-    assert_status status
-    headers.each do |header, value|
-      assert_header header, value
-    end
-  end
-
-  def assert_content_type(type)
-    assert_equal type, response.headers["Content-Type"]
-  end
-
-  def assert_header(name, value)
-    assert_equal value, response.headers[name]
-  end
-end
-
-ActionView::RoutingUrlFor.send(:include, ActionDispatch::Routing::UrlFor)
+ActionView::RoutingUrlFor.include(ActionDispatch::Routing::UrlFor)
 
 module ActionController
   class Base
@@ -338,8 +281,6 @@ def jruby_skip(message = '')
 end
 
 require 'mocha/setup' # FIXME: stop using mocha
-
-# FIXME: we have tests that depend on run order, we should fix that and
-# remove this method call.
-require 'active_support/test_case'
-ActiveSupport::TestCase.test_order = :sorted
+class ActiveSupport::TestCase
+  include ActiveSupport::Testing::MethodCallAssertions
+end
diff --git a/actionview/test/actionpack/abstract/layouts_test.rb b/actionview/test/actionpack/abstract/layouts_test.rb
index a6786d9b6b..80bc665b0a 100644
--- a/actionview/test/actionpack/abstract/layouts_test.rb
+++ b/actionview/test/actionpack/abstract/layouts_test.rb
@@ -52,7 +52,7 @@ module AbstractControllerTests
       end
 
       def overwrite_skip
-        render :text => "Hello text!"
+        render plain: "Hello text!"
       end
     end
 
@@ -371,7 +371,7 @@ module AbstractControllerTests
       test "layout for anonymous controller" do
         klass = Class.new(WithString) do
           def index
-            render :text => 'index', :layout => true
+            render plain: 'index', layout: true
           end
         end
 
diff --git a/actionview/test/actionpack/abstract/render_test.rb b/actionview/test/actionpack/abstract/render_test.rb
index d09f91c1e2..e185b76adb 100644
--- a/actionview/test/actionpack/abstract/render_test.rb
+++ b/actionview/test/actionpack/abstract/render_test.rb
@@ -33,7 +33,7 @@ module AbstractController
       end
 
       def text
-        render :text => "With Text"
+        render plain: "With Text"
       end
 
       def default
diff --git a/actionview/test/actionpack/abstract/views/abstract_controller/testing/me5/index.erb b/actionview/test/actionpack/abstract/views/abstract_controller/testing/me5/index.erb
deleted file mode 100644
index 84d0b7417e..0000000000
--- a/actionview/test/actionpack/abstract/views/abstract_controller/testing/me5/index.erb
+++ /dev/null
@@ -1 +0,0 @@
-Hello from me5/index.erb
\ No newline at end of file
diff --git a/actionview/test/actionpack/controller/capture_test.rb b/actionview/test/actionpack/controller/capture_test.rb
index f8387b27b0..933456ce9d 100644
--- a/actionview/test/actionpack/controller/capture_test.rb
+++ b/actionview/test/actionpack/controller/capture_test.rb
@@ -54,7 +54,7 @@ class CaptureTest < ActionController::TestCase
     assert_equal expected_content_for_output, @response.body
   end
 
-  def test_should_concatentate_content_for
+  def test_should_concatenate_content_for
     get :content_for_concatenated
     assert_equal expected_content_for_output, @response.body
   end
diff --git a/actionview/test/actionpack/controller/layout_test.rb b/actionview/test/actionpack/controller/layout_test.rb
index 7b8a83e2fe..64bc4c41d6 100644
--- a/actionview/test/actionpack/controller/layout_test.rb
+++ b/actionview/test/actionpack/controller/layout_test.rb
@@ -149,75 +149,75 @@ class LayoutSetInResponseTest < ActionController::TestCase
   def test_layout_set_when_using_default_layout
     @controller = DefaultLayoutController.new
     get :hello
-    assert_template :layout => "layouts/layout_test"
+    assert_includes @response.body, 'layout_test.erb'
   end
 
   def test_layout_set_when_using_streaming_layout
     @controller = StreamingLayoutController.new
     get :hello
-    assert_template :hello
+    assert_includes @response.body, 'layout_test.erb'
   end
 
   def test_layout_set_when_set_in_controller
     @controller = HasOwnLayoutController.new
     get :hello
-    assert_template :layout => "layouts/item"
+    assert_includes @response.body, 'item.erb'
   end
 
   def test_layout_symbol_set_in_controller_returning_nil_falls_back_to_default
     @controller = HasNilLayoutSymbol.new
     get :hello
-    assert_template layout: "layouts/layout_test"
+    assert_includes @response.body, 'layout_test.erb'
   end
 
   def test_layout_proc_set_in_controller_returning_nil_falls_back_to_default
     @controller = HasNilLayoutProc.new
     get :hello
-    assert_template layout: "layouts/layout_test"
+    assert_includes @response.body, 'layout_test.erb'
   end
 
   def test_layout_only_exception_when_included
     @controller = OnlyLayoutController.new
     get :hello
-    assert_template :layout => "layouts/item"
+    assert_includes @response.body, 'item.erb'
   end
 
   def test_layout_only_exception_when_excepted
     @controller = OnlyLayoutController.new
     get :goodbye
-    assert !@response.body.include?("item.erb"), "#{@response.body.inspect} included 'item.erb'"
+    assert_not_includes @response.body, 'item.erb'
   end
 
   def test_layout_except_exception_when_included
     @controller = ExceptLayoutController.new
     get :hello
-    assert_template :layout => "layouts/item"
+    assert_includes @response.body, 'item.erb'
   end
 
   def test_layout_except_exception_when_excepted
     @controller = ExceptLayoutController.new
     get :goodbye
-    assert !@response.body.include?("item.erb"), "#{@response.body.inspect} included 'item.erb'"
+    assert_not_includes @response.body, 'item.erb'
   end
 
   def test_layout_set_when_using_render
     with_template_handler :mab, lambda { |template| template.source.inspect } do
       @controller = SetsLayoutInRenderController.new
       get :hello
-      assert_template :layout => "layouts/third_party_template_library"
+      assert_includes @response.body, 'layouts/third_party_template_library.mab'
     end
   end
 
   def test_layout_is_not_set_when_none_rendered
     @controller = RendersNoLayoutController.new
     get :hello
-    assert_template :layout => nil
+    assert_equal 'hello.erb', @response.body
   end
 
   def test_layout_is_picked_from_the_controller_instances_view_path
     @controller = PrependsViewPathController.new
     get :hello
-    assert_template :layout => /layouts\/alt/
+    assert_includes @response.body, 'alt.erb'
   end
 
   def test_absolute_pathed_layout
@@ -262,7 +262,7 @@ unless RbConfig::CONFIG['host_os'] =~ /mswin|mingw/
       @controller = LayoutSymlinkedTest.new
       get :hello
       assert_response 200
-      assert_template :layout => "layouts/symlinked/symlinked_layout"
+      assert_includes @response.body, 'This is my layout'
     end
   end
 end
diff --git a/actionview/test/actionpack/controller/render_test.rb b/actionview/test/actionpack/controller/render_test.rb
index 563caee8a2..bdb9e0397b 100644
--- a/actionview/test/actionpack/controller/render_test.rb
+++ b/actionview/test/actionpack/controller/render_test.rb
@@ -1,5 +1,5 @@
 require 'abstract_unit'
-require "active_model"
+require 'active_model'
 
 class ApplicationController < ActionController::Base
   self.view_paths = File.join(FIXTURE_LOAD_PATH, "actionpack")
@@ -31,6 +31,10 @@ class Customer < Struct.new(:name, :id)
   def persisted?
     id.present?
   end
+
+  def cache_key
+    name.to_s
+  end
 end
 
 module Quiz
@@ -117,7 +121,7 @@ class TestController < ApplicationController
   # :ported:
   def render_hello_world_from_variable
     @person = "david"
-    render :text => "hello #{@person}"
+    render plain: "hello #{@person}"
   end
 
   # :ported:
@@ -139,13 +143,13 @@ class TestController < ApplicationController
 
   # :ported:
   def render_text_hello_world
-    render :text => "hello world"
+    render plain: "hello world"
   end
 
   # :ported:
   def render_text_hello_world_with_layout
     @variable_for_layout = ", I am here!"
-    render :text => "hello world", :layout => true
+    render plain: "hello world", :layout => true
   end
 
   def hello_world_with_layout_false
@@ -208,26 +212,26 @@ class TestController < ApplicationController
 
   # :ported:
   def render_custom_code
-    render :text => "hello world", :status => 404
+    render plain: "hello world", :status => 404
   end
 
   # :ported:
   def render_text_with_nil
-    render :text => nil
+    render plain: nil
   end
 
   # :ported:
   def render_text_with_false
-    render :text => false
+    render plain: false
   end
 
   def render_text_with_resource
-    render :text => Customer.new("David")
+    render plain: Customer.new("David")
   end
 
   # :ported:
   def render_nothing_with_appendix
-    render :text => "appended"
+    render plain: "appended"
   end
 
   # This test is testing 3 things:
@@ -258,7 +262,7 @@ class TestController < ApplicationController
 
   # :ported:
   def blank_response
-    render :text => ' '
+    render plain: ' '
   end
 
   # :ported:
@@ -290,7 +294,7 @@ class TestController < ApplicationController
 
   def hello_in_a_string
     @customers = [ Customer.new("david"), Customer.new("mary") ]
-    render :text => "How's there? " + render_to_string(:template => "test/list")
+    render plain: "How's there? " + render_to_string(:template => "test/list")
   end
 
   def accessing_params_in_template
@@ -353,12 +357,12 @@ class TestController < ApplicationController
   end
 
   def rendering_nothing_on_layout
-    render :nothing => true
+    head :ok
   end
 
   def render_to_string_with_assigns
     @before = "i'm before the render"
-    render_to_string :text => "foo"
+    render_to_string plain: "foo"
     @after = "i'm after the render"
     render :template => "test/hello_world"
   end
@@ -405,8 +409,8 @@ class TestController < ApplicationController
 
   # :ported:
   def double_render
-    render :text => "hello"
-    render :text => "world"
+    render plain: "hello"
+    render plain: "world"
   end
 
   def double_redirect
@@ -415,13 +419,13 @@ class TestController < ApplicationController
   end
 
   def render_and_redirect
-    render :text => "hello"
+    render plain: "hello"
     redirect_to :action => "double_render"
   end
 
   def render_to_string_and_render
-    @stuff = render_to_string :text => "here is some cached stuff"
-    render :text => "Hi web users! #{@stuff}"
+    @stuff = render_to_string plain: "here is some cached stuff"
+    render plain: "Hi web users! #{@stuff}"
   end
 
   def render_to_string_with_inline_and_render
@@ -450,7 +454,11 @@ class TestController < ApplicationController
   # :addressed:
   def render_text_with_assigns
     @hello = "world"
-    render :text => "foo"
+    render plain: "foo"
+  end
+
+  def render_with_assigns_option
+    render inline: '<%= @hello %>', assigns: { hello: "world" }
   end
 
   def yield_content_for
@@ -458,8 +466,8 @@ class TestController < ApplicationController
   end
 
   def render_content_type_from_body
-    response.content_type = Mime::RSS
-    render :text => "hello world!"
+    response.content_type = Mime[:rss]
+    render body: "hello world!"
   end
 
   def render_using_layout_around_block
@@ -675,20 +683,19 @@ class RenderTest < ActionController::TestCase
     get :hello_world
     assert_response 200
     assert_response :success
-    assert_template "test/hello_world"
     assert_equal "<html>Hello world!</html>", @response.body
   end
 
   # :ported:
   def test_renders_default_template_for_missing_action
     get :'hyphen-ated'
-    assert_template 'test/hyphen-ated'
+    assert_equal "hyphen-ated.erb", @response.body
   end
 
   # :ported:
   def test_render
     get :render_hello_world
-    assert_template "test/hello_world"
+    assert_equal "Hello world!", @response.body
   end
 
   def test_line_offset
@@ -704,26 +711,24 @@ class RenderTest < ActionController::TestCase
   # :ported: compatibility
   def test_render_with_forward_slash
     get :render_hello_world_with_forward_slash
-    assert_template "test/hello_world"
+    assert_equal "Hello world!", @response.body
   end
 
   # :ported:
   def test_render_in_top_directory
     get :render_template_in_top_directory
-    assert_template "shared"
     assert_equal "Elastica", @response.body
   end
 
   # :ported:
   def test_render_in_top_directory_with_slash
     get :render_template_in_top_directory_with_slash
-    assert_template "shared"
     assert_equal "Elastica", @response.body
   end
 
   def test_render_process
     get :render_action_hello_world_as_string
-    assert_equal ["Hello world!"], @controller.process(:render_action_hello_world_as_string)
+    assert_equal "Hello world!", @controller.process(:render_action_hello_world_as_string)
   end
 
   # :ported:
@@ -735,7 +740,7 @@ class RenderTest < ActionController::TestCase
   # :ported:
   def test_render_action
     get :render_action_hello_world
-    assert_template "test/hello_world"
+    assert_equal "Hello world!", @response.body
   end
 
   def test_render_action_upcased
@@ -748,13 +753,12 @@ class RenderTest < ActionController::TestCase
   def test_render_action_hello_world_as_string
     get :render_action_hello_world_as_string
     assert_equal "Hello world!", @response.body
-    assert_template "test/hello_world"
   end
 
   # :ported:
   def test_render_action_with_symbol
     get :render_action_hello_world_with_symbol
-    assert_template "test/hello_world"
+    assert_equal "Hello world!", @response.body
   end
 
   # :ported:
@@ -766,7 +770,7 @@ class RenderTest < ActionController::TestCase
   # :ported:
   def test_do_with_render_text_and_layout
     get :render_text_hello_world_with_layout
-    assert_equal "<html>hello world, I am here!</html>", @response.body
+    assert_equal "{{hello world, I am here!}}\n", @response.body
   end
 
   # :ported:
@@ -857,12 +861,12 @@ class RenderTest < ActionController::TestCase
 
   # :ported:
   def test_attempt_to_access_object_method
-    assert_raise(AbstractController::ActionNotFound, "No action responded to [clone]") { get :clone }
+    assert_raise(AbstractController::ActionNotFound) { get :clone }
   end
 
   # :ported:
   def test_private_methods
-    assert_raise(AbstractController::ActionNotFound, "No action responded to [determine_layout]") { get :determine_layout }
+    assert_raise(AbstractController::ActionNotFound) { get :determine_layout }
   end
 
   # :ported:
@@ -942,7 +946,7 @@ class RenderTest < ActionController::TestCase
 
   def test_render_to_string_inline
     get :render_to_string_with_inline_and_render
-    assert_template "test/hello_world"
+    assert_equal 'Hello world!', @response.body
   end
 
   # :ported:
@@ -953,23 +957,23 @@ class RenderTest < ActionController::TestCase
   end
 
   def test_accessing_params_in_template
-    get :accessing_params_in_template, :name => "David"
+    get :accessing_params_in_template, params: { name: "David" }
     assert_equal "Hello: David", @response.body
   end
 
   def test_accessing_local_assigns_in_inline_template
-    get :accessing_local_assigns_in_inline_template, :local_name => "Local David"
+    get :accessing_local_assigns_in_inline_template, params: { local_name: "Local David" }
     assert_equal "Goodbye, Local David", @response.body
     assert_equal "text/html", @response.content_type
   end
 
   def test_should_implicitly_render_html_template_from_xhr_request
-    xhr :get, :render_implicit_html_template_from_xhr_request
+    get :render_implicit_html_template_from_xhr_request, xhr: true
     assert_equal "XHR!\nHello HTML!", @response.body
   end
 
   def test_should_implicitly_render_js_template_without_layout
-    xhr :get, :render_implicit_js_template_without_layout, :format => :js
+    get :render_implicit_js_template_without_layout, format: :js, xhr: true
     assert_no_match %r{<html>}, @response.body
   end
 
@@ -1027,8 +1031,8 @@ class RenderTest < ActionController::TestCase
 
   def test_render_to_string_doesnt_break_assigns
     get :render_to_string_with_assigns
-    assert_equal "i'm before the render", assigns(:before)
-    assert_equal "i'm after the render", assigns(:after)
+    assert_equal "i'm before the render", @controller.instance_variable_get(:@before)
+    assert_equal "i'm after the render", @controller.instance_variable_get(:@after)
   end
 
   def test_bad_render_to_string_still_throws_exception
@@ -1037,12 +1041,12 @@ class RenderTest < ActionController::TestCase
 
   def test_render_to_string_that_throws_caught_exception_doesnt_break_assigns
     assert_nothing_raised { get :render_to_string_with_caught_exception }
-    assert_equal "i'm before the render", assigns(:before)
-    assert_equal "i'm after the render", assigns(:after)
+    assert_equal "i'm before the render", @controller.instance_variable_get(:@before)
+    assert_equal "i'm after the render", @controller.instance_variable_get(:@after)
   end
 
   def test_accessing_params_in_template_with_layout
-    get :accessing_params_in_template_with_layout, :name => "David"
+    get :accessing_params_in_template_with_layout, params: { name: "David" }
     assert_equal "<html>Hello: David</html>", @response.body
   end
 
@@ -1099,7 +1103,12 @@ class RenderTest < ActionController::TestCase
   # :addressed:
   def test_render_text_with_assigns
     get :render_text_with_assigns
-    assert_equal "world", assigns["hello"]
+    assert_equal "world", @controller.instance_variable_get(:@hello)
+  end
+
+  def test_render_text_with_assigns_option
+    get :render_with_assigns_option
+    assert_equal 'world', response.body
   end
 
   # :ported:
@@ -1113,7 +1122,7 @@ class RenderTest < ActionController::TestCase
     assert_equal "<title>Putting stuff in the title!</title>\nGreat stuff!\n", @response.body
   end
 
-  def test_overwritting_rendering_relative_file_with_extension
+  def test_overwriting_rendering_relative_file_with_extension
     get :hello_world_from_rxml_using_template
     assert_equal "<html>\n  <p>Hello</p>\n</html>\n", @response.body
 
@@ -1160,22 +1169,22 @@ class RenderTest < ActionController::TestCase
 
   def test_render_to_string_partial
     get :render_to_string_with_partial
-    assert_equal "only partial", assigns(:partial_only)
-    assert_equal "Hello: david", assigns(:partial_with_locals)
+    assert_equal "only partial", @controller.instance_variable_get(:@partial_only)
+    assert_equal "Hello: david", @controller.instance_variable_get(:@partial_with_locals)
     assert_equal "text/html", @response.content_type
   end
 
   def test_render_to_string_with_template_and_html_partial
     get :render_to_string_with_template_and_html_partial
-    assert_equal "**only partial**\n", assigns(:text)
-    assert_equal "<strong>only partial</strong>\n", assigns(:html)
+    assert_equal "**only partial**\n", @controller.instance_variable_get(:@text)
+    assert_equal "<strong>only partial</strong>\n", @controller.instance_variable_get(:@html)
     assert_equal "<strong>only html partial</strong>\n", @response.body
     assert_equal "text/html", @response.content_type
   end
 
   def test_render_to_string_and_render_with_different_formats
     get :render_to_string_and_render_with_different_formats
-    assert_equal "<strong>only partial</strong>\n", assigns(:html)
+    assert_equal "<strong>only partial</strong>\n", @controller.instance_variable_get(:@html)
     assert_equal "**only partial**\n", @response.body
     assert_equal "text/plain", @response.content_type
   end
@@ -1199,21 +1208,18 @@ class RenderTest < ActionController::TestCase
 
   def test_partial_with_form_builder
     get :partial_with_form_builder
-    assert_match(/<label/, @response.body)
-    assert_template('test/_form')
+    assert_equal "<label for=\"post_title\">Title</label>\n", @response.body
   end
 
   def test_partial_with_form_builder_subclass
     get :partial_with_form_builder_subclass
-    assert_match(/<label/, @response.body)
-    assert_template('test/_labelling_form')
+    assert_equal "<label for=\"post_title\">Title</label>\n", @response.body
   end
 
   def test_nested_partial_with_form_builder
     @controller = Fun::GamesController.new
     get :nested_partial_with_form_builder
-    assert_match(/<label/, @response.body)
-    assert_template('fun/games/_form')
+    assert_equal "<label for=\"post_title\">Title</label>\n", @response.body
   end
 
   def test_namespaced_object_partial
@@ -1257,48 +1263,29 @@ class RenderTest < ActionController::TestCase
     assert_equal "Bonjour: davidBonjour: mary", @response.body
   end
 
-  def test_locals_option_to_assert_template_is_not_supported
-    get :partial_collection_with_locals
-
-    warning_buffer = StringIO.new
-    $stderr = warning_buffer
-
-    assert_template partial: 'customer_greeting', locals: { greeting: 'Bonjour' }
-    assert_equal "the :locals option to #assert_template is only supported in a ActionView::TestCase\n", warning_buffer.string
-  ensure
-    $stderr = STDERR
-  end
-
   def test_partial_collection_with_spacer
     get :partial_collection_with_spacer
     assert_equal "Hello: davidonly partialHello: mary", @response.body
-    assert_template :partial => '_customer'
   end
 
   def test_partial_collection_with_spacer_which_uses_render
     get :partial_collection_with_spacer_which_uses_render
     assert_equal "Hello: davidpartial html\npartial with partial\nHello: mary", @response.body
-    assert_template :partial => '_customer'
   end
 
   def test_partial_collection_shorthand_with_locals
     get :partial_collection_shorthand_with_locals
     assert_equal "Bonjour: davidBonjour: mary", @response.body
-    assert_template :partial => 'customers/_customer', :count => 2
-    assert_template :partial => '_completely_fake_and_made_up_template_that_cannot_possibly_be_rendered', :count => 0
   end
 
   def test_partial_collection_shorthand_with_different_types_of_records
     get :partial_collection_shorthand_with_different_types_of_records
     assert_equal "Bonjour bad customer: mark0Bonjour good customer: craig1Bonjour bad customer: john2Bonjour good customer: zach3Bonjour good customer: brandon4Bonjour bad customer: dan5", @response.body
-    assert_template :partial => 'good_customers/_good_customer', :count => 3
-    assert_template :partial => 'bad_customers/_bad_customer', :count => 3
   end
 
   def test_empty_partial_collection
     get :empty_partial_collection
     assert_equal " ", @response.body
-    assert_template :partial => false
   end
 
   def test_partial_with_hash_object
diff --git a/actionview/test/actionpack/controller/view_paths_test.rb b/actionview/test/actionpack/controller/view_paths_test.rb
index 7fba9ff8ff..e99659c802 100644
--- a/actionview/test/actionpack/controller/view_paths_test.rb
+++ b/actionview/test/actionpack/controller/view_paths_test.rb
@@ -23,8 +23,8 @@ class ViewLoadPathsTest < ActionController::TestCase
   end
 
   def setup
-    @request  = ActionController::TestRequest.new
-    @response = ActionController::TestResponse.new
+    @request  = ActionController::TestRequest.create
+    @response = ActionDispatch::TestResponse.new
     @controller = TestController.new
     @paths = TestController.view_paths
   end
diff --git a/actionview/test/active_record_unit.rb b/actionview/test/active_record_unit.rb
index cca55c9af4..f9e94413b5 100644
--- a/actionview/test/active_record_unit.rb
+++ b/actionview/test/active_record_unit.rb
@@ -76,7 +76,7 @@ class ActiveRecordTestCase < ActionController::TestCase
   # Set our fixture path
   if ActiveRecordTestConnector.able_to_connect
     self.fixture_path = [FIXTURE_LOAD_PATH]
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
   end
 
   def self.fixtures(*args)
diff --git a/actionview/test/activerecord/controller_runtime_test.rb b/actionview/test/activerecord/controller_runtime_test.rb
index 469adff39a..af91348d76 100644
--- a/actionview/test/activerecord/controller_runtime_test.rb
+++ b/actionview/test/activerecord/controller_runtime_test.rb
@@ -4,7 +4,7 @@ require 'fixtures/project'
 require 'active_support/log_subscriber/test_helper'
 require 'action_controller/log_subscriber'
 
-ActionController::Base.send :include, ActiveRecord::Railties::ControllerRuntime
+ActionController::Base.include(ActiveRecord::Railties::ControllerRuntime)
 
 class ControllerRuntimeLogSubscriberTest < ActionController::TestCase
   class LogSubscriberController < ActionController::Base
diff --git a/actionview/test/activerecord/debug_helper_test.rb b/actionview/test/activerecord/debug_helper_test.rb
index 5609694cd5..03cb1d5a91 100644
--- a/actionview/test/activerecord/debug_helper_test.rb
+++ b/actionview/test/activerecord/debug_helper_test.rb
@@ -1,8 +1,14 @@
 require 'active_record_unit'
+require 'nokogiri'
 
 class DebugHelperTest < ActionView::TestCase
   def test_debug
     company = Company.new(name: "firebase")
     assert_match "name: firebase", debug(company)
   end
+
+  def test_debug_with_marshal_error
+    obj = -> { }
+    assert_match obj.inspect, Nokogiri.XML(debug(obj)).content
+  end
 end
diff --git a/actionview/test/activerecord/form_helper_activerecord_test.rb b/actionview/test/activerecord/form_helper_activerecord_test.rb
index 0a62f49f35..2769b97445 100644
--- a/actionview/test/activerecord/form_helper_activerecord_test.rb
+++ b/actionview/test/activerecord/form_helper_activerecord_test.rb
@@ -35,10 +35,6 @@ class FormHelperActiveRecordTest < ActionView::TestCase
     end
   end
 
-  def _routes
-    Routes
-  end
-
   include Routes.url_helpers
 
   def test_nested_fields_for_with_child_index_option_override_on_a_nested_attributes_collection_association
diff --git a/actionview/test/activerecord/polymorphic_routes_test.rb b/actionview/test/activerecord/polymorphic_routes_test.rb
index 8e1ed2776d..34b2698c7f 100644
--- a/actionview/test/activerecord/polymorphic_routes_test.rb
+++ b/actionview/test/activerecord/polymorphic_routes_test.rb
@@ -113,7 +113,7 @@ class PolymorphicRoutesTest < ActionController::TestCase
 
   def test_passing_routes_proxy
     with_namespaced_routes(:blog) do
-      proxy = ActionDispatch::Routing::RoutesProxy.new(_routes, self)
+      proxy = ActionDispatch::Routing::RoutesProxy.new(_routes, self, _routes.url_helpers)
       @blog_post.save
       assert_url "http://example.com/posts/#{@blog_post.id}", [proxy, @blog_post]
     end
@@ -208,7 +208,7 @@ class PolymorphicRoutesTest < ActionController::TestCase
         @series.save
         polymorphic_url([nil, @series])
       end
-      assert_match(/undefined method `series_url' for/, exception.message)
+      assert_match(/undefined method `series_url'/, exception.message)
     end
   end
 
diff --git a/actionview/test/activerecord/relation_cache_test.rb b/actionview/test/activerecord/relation_cache_test.rb
new file mode 100644
index 0000000000..8e97417b94
--- /dev/null
+++ b/actionview/test/activerecord/relation_cache_test.rb
@@ -0,0 +1,18 @@
+require 'active_record_unit'
+
+class RelationCacheTest <  ActionView::TestCase
+  tests ActionView::Helpers::CacheHelper
+
+  def setup
+    @virtual_path = "path"
+    controller.cache_store = ActiveSupport::Cache::MemoryStore.new
+  end
+
+  def test_cache_relation_other
+    cache(Project.all){ concat("Hello World") }
+    assert_equal "Hello World", controller.cache_store.read("views/projects-#{Project.count}/")
+  end
+
+  def view_cache_dependencies; end
+
+end
diff --git a/actionview/test/activerecord/render_partial_with_record_identification_test.rb b/actionview/test/activerecord/render_partial_with_record_identification_test.rb
index 409370104d..9772ebb39e 100644
--- a/actionview/test/activerecord/render_partial_with_record_identification_test.rb
+++ b/actionview/test/activerecord/render_partial_with_record_identification_test.rb
@@ -52,43 +52,37 @@ class RenderPartialWithRecordIdentificationTest < ActiveRecordTestCase
 
   def test_rendering_partial_with_has_many_and_belongs_to_association
     get :render_with_has_many_and_belongs_to_association
-    assert_template 'projects/_project'
-    assert_equal assigns(:developer).projects.map(&:name).join, @response.body
+    assert_equal Developer.find(1).projects.map(&:name).join, @response.body
   end
 
   def test_rendering_partial_with_has_many_association
     get :render_with_has_many_association
-    assert_template 'replies/_reply'
     assert_equal 'Birdman is better!', @response.body
   end
 
   def test_rendering_partial_with_scope
     get :render_with_scope
-    assert_template 'replies/_reply'
     assert_equal 'Birdman is better!Nuh uh!', @response.body
   end
 
   def test_render_with_record
     get :render_with_record
-    assert_template 'developers/_developer'
     assert_equal 'David', @response.body
   end
 
   def test_render_with_record_collection
     get :render_with_record_collection
-    assert_template 'developers/_developer'
     assert_equal 'DavidJamisfixture_3fixture_4fixture_5fixture_6fixture_7fixture_8fixture_9fixture_10Jamis', @response.body
   end
 
   def test_render_with_record_collection_and_spacer_template
     get :render_with_record_collection_and_spacer_template
-    assert_equal assigns(:developer).projects.map(&:name).join('only partial'), @response.body
+    assert_equal Developer.find(1).projects.map(&:name).join('only partial'), @response.body
   end
 
   def test_rendering_partial_with_has_one_association
     mascot = Company.find(1).mascot
     get :render_with_has_one_association
-    assert_template 'mascots/_mascot'
     assert_equal mascot.name, @response.body
   end
 end
@@ -130,13 +124,11 @@ class RenderPartialWithRecordIdentificationAndNestedControllersTest < ActiveReco
 
   def test_render_with_record_in_nested_controller
     get :render_with_record_in_nested_controller
-    assert_template %r{\Afun/games/_game\Z}
     assert_equal "Fun Pong\n", @response.body
   end
 
   def test_render_with_record_collection_in_nested_controller
     get :render_with_record_collection_in_nested_controller
-    assert_template %r{\Afun/games/_game\Z}
     assert_equal "Fun Pong\nFun Tank\n", @response.body
   end
 end
@@ -149,7 +141,6 @@ class RenderPartialWithRecordIdentificationAndNestedControllersWithoutPrefixTest
     ActionView::Base.prefix_partial_path_with_controller_namespace = false
 
     get :render_with_record_in_nested_controller
-    assert_template %r{\Agames/_game\Z}
     assert_equal "Just Pong\n", @response.body
   ensure
     ActionView::Base.prefix_partial_path_with_controller_namespace = old_config
@@ -160,7 +151,6 @@ class RenderPartialWithRecordIdentificationAndNestedControllersWithoutPrefixTest
     ActionView::Base.prefix_partial_path_with_controller_namespace = false
 
     get :render_with_record_collection_in_nested_controller
-    assert_template %r{\Agames/_game\Z}
     assert_equal "Just Pong\nJust Tank\n", @response.body
   ensure
     ActionView::Base.prefix_partial_path_with_controller_namespace = old_config
@@ -172,13 +162,11 @@ class RenderPartialWithRecordIdentificationAndNestedDeeperControllersTest < Acti
 
   def test_render_with_record_in_deeper_nested_controller
     get :render_with_record_in_deeper_nested_controller
-    assert_template %r{\Afun/serious/games/_game\Z}
     assert_equal "Serious Chess\n", @response.body
   end
 
   def test_render_with_record_collection_in_deeper_nested_controller
     get :render_with_record_collection_in_deeper_nested_controller
-    assert_template %r{\Afun/serious/games/_game\Z}
     assert_equal "Serious Chess\nSerious Sudoku\nSerious Solitaire\n", @response.body
   end
 end
@@ -191,7 +179,6 @@ class RenderPartialWithRecordIdentificationAndNestedDeeperControllersWithoutPref
     ActionView::Base.prefix_partial_path_with_controller_namespace = false
 
     get :render_with_record_in_deeper_nested_controller
-    assert_template %r{\Agames/_game\Z}
     assert_equal "Just Chess\n", @response.body
   ensure
     ActionView::Base.prefix_partial_path_with_controller_namespace = old_config
@@ -202,7 +189,6 @@ class RenderPartialWithRecordIdentificationAndNestedDeeperControllersWithoutPref
     ActionView::Base.prefix_partial_path_with_controller_namespace = false
 
     get :render_with_record_collection_in_deeper_nested_controller
-    assert_template %r{\Agames/_game\Z}
     assert_equal "Just Chess\nJust Sudoku\nJust Solitaire\n", @response.body
   ensure
     ActionView::Base.prefix_partial_path_with_controller_namespace = old_config
diff --git a/actionview/test/fixtures/actionpack/layout_tests/alt/layouts/alt.erb b/actionview/test/fixtures/actionpack/layout_tests/alt/layouts/alt.erb
index e69de29bb2..60b81525b5 100644
--- a/actionview/test/fixtures/actionpack/layout_tests/alt/layouts/alt.erb
+++ b/actionview/test/fixtures/actionpack/layout_tests/alt/layouts/alt.erb
@@ -0,0 +1 @@
+alt.erb
diff --git a/actionview/test/fixtures/actionpack/layouts/standard.text.erb b/actionview/test/fixtures/actionpack/layouts/standard.text.erb
new file mode 100644
index 0000000000..a58afb1aa2
--- /dev/null
+++ b/actionview/test/fixtures/actionpack/layouts/standard.text.erb
@@ -0,0 +1 @@
+{{<%= yield %><%= @variable_for_layout %>}}
diff --git a/actionview/test/fixtures/actionpack/test/hyphen-ated.erb b/actionview/test/fixtures/actionpack/test/hyphen-ated.erb
index cd0875583a..28dbe94ee1 100644
--- a/actionview/test/fixtures/actionpack/test/hyphen-ated.erb
+++ b/actionview/test/fixtures/actionpack/test/hyphen-ated.erb
@@ -1 +1 @@
-Hello world!
+hyphen-ated.erb
\ No newline at end of file
diff --git a/actionview/test/fixtures/digestor/comments/_comment.html.erb b/actionview/test/fixtures/digestor/comments/_comment.html.erb
index f172e749da..a8fa21f644 100644
--- a/actionview/test/fixtures/digestor/comments/_comment.html.erb
+++ b/actionview/test/fixtures/digestor/comments/_comment.html.erb
@@ -1 +1 @@
-Great story, bro!
+Great story!
diff --git a/actionview/test/fixtures/digestor/events/_completed.html.erb b/actionview/test/fixtures/digestor/events/_completed.html.erb
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/actionview/test/fixtures/digestor/events/_completed.html.erb
diff --git a/actionview/test/fixtures/digestor/events/index.html.erb b/actionview/test/fixtures/digestor/events/index.html.erb
new file mode 100644
index 0000000000..bc45e41bcb
--- /dev/null
+++ b/actionview/test/fixtures/digestor/events/index.html.erb
@@ -0,0 +1 @@
+<% # Template Dependency: events/* %>
\ No newline at end of file
diff --git a/actionview/test/fixtures/layouts/streaming_with_capture.erb b/actionview/test/fixtures/layouts/streaming_with_capture.erb
new file mode 100644
index 0000000000..538c19ce3a
--- /dev/null
+++ b/actionview/test/fixtures/layouts/streaming_with_capture.erb
@@ -0,0 +1,6 @@
+<%= yield :header -%>
+<%= capture do %>
+ this works
+<% end %>
+<%= yield :footer -%>
+<%= yield(:unknown).presence || "." -%>
diff --git a/actionview/test/fixtures/multipart/bracketed_utf8_param b/actionview/test/fixtures/multipart/bracketed_utf8_param
deleted file mode 100644
index df9cecea08..0000000000
--- a/actionview/test/fixtures/multipart/bracketed_utf8_param
+++ /dev/null
@@ -1,5 +0,0 @@
---AaB03x
-Content-Disposition: form-data; name="Iñtërnâtiônàlizætiøn_name[Iñtërnâtiônàlizætiøn_nested_name]"
-
-Iñtërnâtiônàlizætiøn_value
---AaB03x--
diff --git a/actionview/test/fixtures/multipart/single_utf8_param b/actionview/test/fixtures/multipart/single_utf8_param
deleted file mode 100644
index 1d9fae7b17..0000000000
--- a/actionview/test/fixtures/multipart/single_utf8_param
+++ /dev/null
@@ -1,5 +0,0 @@
---AaB03x
-Content-Disposition: form-data; name="Iñtërnâtiônàlizætiøn_name"
-
-Iñtërnâtiônàlizætiøn_value
---AaB03x--
diff --git a/actionview/test/fixtures/project.rb b/actionview/test/fixtures/project.rb
index c124a9e605..404b12cbab 100644
--- a/actionview/test/fixtures/project.rb
+++ b/actionview/test/fixtures/project.rb
@@ -1,3 +1,7 @@
 class Project < ActiveRecord::Base
   has_and_belongs_to_many :developers, -> { uniq }
+
+  def self.collection_cache_key(collection = all, timestamp_column = :updated_at)
+    "projects-#{collection.count}"
+  end
 end
diff --git a/actionview/test/fixtures/test/_FooBar.html.erb b/actionview/test/fixtures/test/_FooBar.html.erb
new file mode 100644
index 0000000000..4bbe59410a
--- /dev/null
+++ b/actionview/test/fixtures/test/_FooBar.html.erb
@@ -0,0 +1 @@
+🍣
diff --git a/actionview/test/fixtures/test/_a-in.html.erb b/actionview/test/fixtures/test/_a-in.html.erb
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/actionview/test/fixtures/test/_a-in.html.erb
diff --git a/actionview/test/fixtures/test/_cached_customer.erb b/actionview/test/fixtures/test/_cached_customer.erb
new file mode 100644
index 0000000000..52f35a3497
--- /dev/null
+++ b/actionview/test/fixtures/test/_cached_customer.erb
@@ -0,0 +1,3 @@
+<% cache cached_customer do %>
+  Hello: <%= cached_customer.name %>
+<% end %>
\ No newline at end of file
diff --git a/actionview/test/fixtures/test/_cached_customer_as.erb b/actionview/test/fixtures/test/_cached_customer_as.erb
new file mode 100644
index 0000000000..fca8d19e34
--- /dev/null
+++ b/actionview/test/fixtures/test/_cached_customer_as.erb
@@ -0,0 +1,3 @@
+<% cache buyer do %>
+  <%= greeting %>: <%= customer.name %>
+<% end %>
\ No newline at end of file
diff --git a/actionview/test/fixtures/test/_partial_name_in_local_assigns.erb b/actionview/test/fixtures/test/_partial_name_in_local_assigns.erb
new file mode 100644
index 0000000000..28ee9f41c5
--- /dev/null
+++ b/actionview/test/fixtures/test/_partial_name_in_local_assigns.erb
@@ -0,0 +1 @@
+<%= local_assigns.has_key?(:partial_name_in_local_assigns) %>
\ No newline at end of file
diff --git a/actionview/test/lib/controller/fake_models.rb b/actionview/test/lib/controller/fake_models.rb
index 789b1d198b..65c68fc34a 100644
--- a/actionview/test/lib/controller/fake_models.rb
+++ b/actionview/test/lib/controller/fake_models.rb
@@ -54,6 +54,22 @@ class Post < Struct.new(:title, :author_name, :body, :secret, :persisted, :writt
   def tags_attributes=(attributes); end
 end
 
+class PostDelegator < Post
+  def to_model
+    PostDelegate.new
+  end
+end
+
+class PostDelegate < Post
+  def self.human_attribute_name(attribute)
+    "Delegate #{super}"
+  end
+
+  def model_name
+    ActiveModel::Name.new(self.class)
+  end
+end
+
 class Comment
   extend ActiveModel::Naming
   include ActiveModel::Conversion
diff --git a/actionview/test/template/asset_tag_helper_test.rb b/actionview/test/template/asset_tag_helper_test.rb
index dac1c7024d..496b33b35e 100644
--- a/actionview/test/template/asset_tag_helper_test.rb
+++ b/actionview/test/template/asset_tag_helper_test.rb
@@ -1,4 +1,3 @@
-require 'zlib'
 require 'abstract_unit'
 require 'active_support/ordered_options'
 
@@ -180,6 +179,7 @@ class AssetTagHelperTest < ActionView::TestCase
     %(image_tag("xml.png")) => %(<img alt="Xml" src="/images/xml.png" />),
     %(image_tag("rss.gif", :alt => "rss syndication")) => %(<img alt="rss syndication" src="/images/rss.gif" />),
     %(image_tag("gold.png", :size => "20")) => %(<img alt="Gold" height="20" src="/images/gold.png" width="20" />),
+    %(image_tag("gold.png", :size => 20)) => %(<img alt="Gold" height="20" src="/images/gold.png" width="20" />),
     %(image_tag("gold.png", :size => "45x70")) => %(<img alt="Gold" height="70" src="/images/gold.png" width="45" />),
     %(image_tag("gold.png", "size" => "45x70")) => %(<img alt="Gold" height="70" src="/images/gold.png" width="45" />),
     %(image_tag("error.png", "size" => "45 x 70")) => %(<img alt="Error" src="/images/error.png" />),
@@ -238,6 +238,7 @@ class AssetTagHelperTest < ActionView::TestCase
     %(video_tag("gold.m4v", "size" => "320x240")) => %(<video height="240" src="/videos/gold.m4v" width="320"></video>),
     %(video_tag("trailer.ogg", :poster => "screenshot.png")) => %(<video poster="/images/screenshot.png" src="/videos/trailer.ogg"></video>),
     %(video_tag("error.avi", "size" => "100")) => %(<video height="100" src="/videos/error.avi" width="100"></video>),
+    %(video_tag("error.avi", "size" => 100)) => %(<video height="100" src="/videos/error.avi" width="100"></video>),
     %(video_tag("error.avi", "size" => "100 x 100")) => %(<video src="/videos/error.avi"></video>),
     %(video_tag("error.avi", "size" => "x")) => %(<video src="/videos/error.avi"></video>),
     %(video_tag("http://media.rubyonrails.org/video/rails_blog_2.mov")) => %(<video src="http://media.rubyonrails.org/video/rails_blog_2.mov"></video>),
@@ -309,6 +310,11 @@ class AssetTagHelperTest < ActionView::TestCase
     AssetPathToTag.each { |method, tag| assert_dom_equal(tag, eval(method)) }
   end
 
+  def test_asset_path_tag_raises_an_error_for_nil_source
+    e = assert_raise(ArgumentError) { asset_path(nil) }
+    assert_equal("nil is not a valid asset source", e.message)
+  end
+
   def test_asset_path_tag_to_not_create_duplicate_slashes
     @controller.config.asset_host = "host/"
     assert_dom_equal('http://host/foo', asset_path("foo"))
@@ -463,6 +469,14 @@ class AssetTagHelperTest < ActionView::TestCase
     assert_equal({:size => '16x10'}, options)
   end
 
+  def test_image_tag_raises_an_error_for_competing_size_arguments
+    exception = assert_raise(ArgumentError) do
+      image_tag("gold.png", :height => "100", :width => "200", :size => "45x70")
+    end
+
+    assert_equal("Cannot pass a :size option with a :height or :width option", exception.message)
+  end
+
   def test_favicon_link_tag
     FaviconLinkToTag.each { |method, tag| assert_dom_equal(tag, eval(method)) }
   end
@@ -574,11 +588,13 @@ class AssetTagHelperTest < ActionView::TestCase
       end
     end
 
-    @controller.request.stubs(:ssl?).returns(false)
-    assert_equal "http://assets15.example.com/images/xml.png", image_path("xml.png")
+    @controller.request.stub(:ssl?, false) do
+      assert_equal "http://assets15.example.com/images/xml.png", image_path("xml.png")
+    end
 
-    @controller.request.stubs(:ssl?).returns(true)
-    assert_equal "http://localhost/images/xml.png", image_path("xml.png")
+    @controller.request.stub(:ssl?, true) do
+      assert_equal "http://localhost/images/xml.png", image_path("xml.png")
+    end
   end
 end
 
diff --git a/actionview/test/template/atom_feed_helper_test.rb b/actionview/test/template/atom_feed_helper_test.rb
index 68b44c4f0d..591cd71404 100644
--- a/actionview/test/template/atom_feed_helper_test.rb
+++ b/actionview/test/template/atom_feed_helper_test.rb
@@ -14,7 +14,7 @@ class ScrollsController < ActionController::Base
   FEEDS["defaults"] = <<-EOT
         atom_feed(:schema_date => '2008') do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           @scrolls.each do |scroll|
             feed.entry(scroll) do |entry|
@@ -31,7 +31,7 @@ class ScrollsController < ActionController::Base
     FEEDS["entry_options"] = <<-EOT
         atom_feed do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           @scrolls.each do |scroll|
             feed.entry(scroll, :url => "/otherstuff/" + scroll.to_param.to_s, :updated => Time.utc(2007, 1, scroll.id)) do |entry|
@@ -48,7 +48,7 @@ class ScrollsController < ActionController::Base
     FEEDS["entry_type_options"] = <<-EOT
         atom_feed(:schema_date => '2008') do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           @scrolls.each do |scroll|
             feed.entry(scroll, :type => 'text/xml') do |entry|
@@ -62,10 +62,27 @@ class ScrollsController < ActionController::Base
           end
         end
     EOT
+    FEEDS["entry_url_false_option"] = <<-EOT
+        atom_feed do |feed|
+          feed.title("My great blog!")
+          feed.updated(@scrolls.first.created_at)
+
+          @scrolls.each do |scroll|
+            feed.entry(scroll, :url => false) do |entry|
+              entry.title(scroll.title)
+              entry.content(scroll.body, :type => 'html')
+
+              entry.author do |author|
+                author.name("DHH")
+              end
+            end
+          end
+        end
+    EOT
     FEEDS["xml_block"] = <<-EOT
         atom_feed do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           feed.author do |author|
             author.name("DHH")
@@ -83,7 +100,7 @@ class ScrollsController < ActionController::Base
         atom_feed({'xmlns:app' => 'http://www.w3.org/2007/app',
                  'xmlns:openSearch' => 'http://a9.com/-/spec/opensearch/1.1/'}) do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           @scrolls.each do |scroll|
             feed.entry(scroll) do |entry|
@@ -101,7 +118,7 @@ class ScrollsController < ActionController::Base
     FEEDS["feed_with_overridden_ids"] = <<-EOT
         atom_feed({:id => 'tag:test.rubyonrails.org,2008:test/'}) do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           @scrolls.each do |scroll|
             feed.entry(scroll, :id => "tag:test.rubyonrails.org,2008:"+scroll.id.to_s) do |entry|
@@ -120,7 +137,7 @@ class ScrollsController < ActionController::Base
         atom_feed(:schema_date => '2008',
           :instruct => {'xml-stylesheet' => { :href=> 't.css', :type => 'text/css' }}) do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           @scrolls.each do |scroll|
             feed.entry(scroll) do |entry|
@@ -138,7 +155,7 @@ class ScrollsController < ActionController::Base
         atom_feed(:schema_date => '2008',
           :instruct => {'target1' => [{ :a => '1', :b => '2' }, { :c => '3', :d => '4' }]}) do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           @scrolls.each do |scroll|
             feed.entry(scroll) do |entry|
@@ -155,7 +172,7 @@ class ScrollsController < ActionController::Base
     FEEDS["feed_with_xhtml_content"] = <<-'EOT'
         atom_feed do |feed|
           feed.title("My great blog!")
-          feed.updated((@scrolls.first.created_at))
+          feed.updated(@scrolls.first.created_at)
 
           @scrolls.each do |scroll|
             feed.entry(scroll) do |entry|
@@ -180,7 +197,7 @@ class ScrollsController < ActionController::Base
           new_xml = Builder::XmlMarkup.new(:target=>'')
           atom_feed(:xml => new_xml) do |feed|
             feed.title("My great blog!")
-            feed.updated((@scrolls.first.created_at))
+            feed.updated(@scrolls.first.created_at)
 
             @scrolls.each do |scroll|
               feed.entry(scroll) do |entry|
@@ -214,28 +231,28 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_feed_should_use_default_language_if_none_is_given
     with_restful_routing(:scrolls) do
-      get :index, :id => "defaults"
+      get :index, params: { id: "defaults" }
       assert_match(%r{xml:lang="en-US"}, @response.body)
     end
   end
 
   def test_feed_should_include_two_entries
     with_restful_routing(:scrolls) do
-      get :index, :id => "defaults"
+      get :index, params: { id: "defaults" }
       assert_select "entry", 2
     end
   end
 
   def test_entry_should_only_use_published_if_created_at_is_present
     with_restful_routing(:scrolls) do
-      get :index, :id => "defaults"
+      get :index, params: { id: "defaults" }
       assert_select "published", 1
     end
   end
 
   def test_providing_builder_to_atom_feed
     with_restful_routing(:scrolls) do
-      get :index, :id=>"provide_builder"
+      get :index, params: { id: "provide_builder" }
       # because we pass in the non-default builder, the content generated by the
       # helper should go 'nowhere'.  Leaving the response body blank.
       assert @response.body.blank?
@@ -244,7 +261,7 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_entry_with_prefilled_options_should_use_those_instead_of_querying_the_record
     with_restful_routing(:scrolls) do
-      get :index, :id => "entry_options"
+      get :index, params: { id: "entry_options" }
 
       assert_select "updated", Time.utc(2007, 1, 1).xmlschema
       assert_select "updated", Time.utc(2007, 1, 2).xmlschema
@@ -253,21 +270,21 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_self_url_should_default_to_current_request_url
     with_restful_routing(:scrolls) do
-      get :index, :id => "defaults"
+      get :index, params: { id: "defaults" }
       assert_select "link[rel=self][href=\"http://www.nextangle.com/scrolls?id=defaults\"]"
     end
   end
 
   def test_feed_id_should_be_a_valid_tag
     with_restful_routing(:scrolls) do
-      get :index, :id => "defaults"
+      get :index, params: { id: "defaults" }
       assert_select "id", :text => "tag:www.nextangle.com,2008:/scrolls?id=defaults"
     end
   end
 
   def test_entry_id_should_be_a_valid_tag
     with_restful_routing(:scrolls) do
-      get :index, :id => "defaults"
+      get :index, params: { id: "defaults" }
       assert_select "entry id", :text => "tag:www.nextangle.com,2008:Scroll/1"
       assert_select "entry id", :text => "tag:www.nextangle.com,2008:Scroll/2"
     end
@@ -275,14 +292,14 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_feed_should_allow_nested_xml_blocks
     with_restful_routing(:scrolls) do
-      get :index, :id => "xml_block"
+      get :index, params: { id: "xml_block" }
       assert_select "author name", :text => "DHH"
     end
   end
 
   def test_feed_should_include_atomPub_namespace
     with_restful_routing(:scrolls) do
-      get :index, :id => "feed_with_atomPub_namespace"
+      get :index, params: { id: "feed_with_atomPub_namespace" }
       assert_match %r{xml:lang="en-US"}, @response.body
       assert_match %r{xmlns="http://www.w3.org/2005/Atom"}, @response.body
       assert_match %r{xmlns:app="http://www.w3.org/2007/app"}, @response.body
@@ -291,7 +308,7 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_feed_should_allow_overriding_ids
     with_restful_routing(:scrolls) do
-      get :index, :id => "feed_with_overridden_ids"
+      get :index, params: { id: "feed_with_overridden_ids" }
       assert_select "id", :text => "tag:test.rubyonrails.org,2008:test/"
       assert_select "entry id", :text => "tag:test.rubyonrails.org,2008:1"
       assert_select "entry id", :text => "tag:test.rubyonrails.org,2008:2"
@@ -300,7 +317,7 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_feed_xml_processing_instructions
     with_restful_routing(:scrolls) do
-      get :index, :id => 'feed_with_xml_processing_instructions'
+      get :index, params: { id: 'feed_with_xml_processing_instructions' }
       assert_match %r{<\?xml-stylesheet [^\?]*type="text/css"}, @response.body
       assert_match %r{<\?xml-stylesheet [^\?]*href="t.css"}, @response.body
     end
@@ -308,7 +325,7 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_feed_xml_processing_instructions_duplicate_targets
     with_restful_routing(:scrolls) do
-      get :index, :id => 'feed_with_xml_processing_instructions_duplicate_targets'
+      get :index, params: { id: 'feed_with_xml_processing_instructions_duplicate_targets' }
       assert_match %r{<\?target1 (a="1" b="2"|b="2" a="1")\?>}, @response.body
       assert_match %r{<\?target1 (c="3" d="4"|d="4" c="3")\?>}, @response.body
     end
@@ -316,7 +333,7 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_feed_xhtml
     with_restful_routing(:scrolls) do
-      get :index, :id => "feed_with_xhtml_content"
+      get :index, params: { id:  "feed_with_xhtml_content" }
       assert_match %r{xmlns="http://www.w3.org/1999/xhtml"}, @response.body
       assert_select "summary", :text => /Something Boring/
       assert_select "summary", :text => /after 2/
@@ -325,18 +342,25 @@ class AtomFeedTest < ActionController::TestCase
 
   def test_feed_entry_type_option_default_to_text_html
     with_restful_routing(:scrolls) do
-      get :index, :id => 'defaults'
+      get :index, params: { id: 'defaults' }
       assert_select "entry link[rel=alternate][type=\"text/html\"]"
     end
   end
 
   def test_feed_entry_type_option_specified
     with_restful_routing(:scrolls) do
-      get :index, :id => 'entry_type_options'
+      get :index, params: { id: 'entry_type_options' }
       assert_select "entry link[rel=alternate][type=\"text/xml\"]"
     end
   end
 
+  def test_feed_entry_url_false_option_adds_no_link
+    with_restful_routing(:scrolls) do
+      get :index, params: { id: 'entry_url_false_option' }
+      assert_select "entry link", false
+    end
+  end
+
   private
     def with_restful_routing(resources)
       with_routing do |set|
diff --git a/actionview/test/template/capture_helper_test.rb b/actionview/test/template/capture_helper_test.rb
index f213da5934..1e099d482c 100644
--- a/actionview/test/template/capture_helper_test.rb
+++ b/actionview/test/template/capture_helper_test.rb
@@ -210,10 +210,4 @@ class CaptureHelperTest < ActionView::TestCase
   def alt_encoding(output_buffer)
     output_buffer.encoding == Encoding::US_ASCII ? Encoding::UTF_8 : Encoding::US_ASCII
   end
-
-  def view_with_controller
-    TestController.new.view_context.tap do |view|
-      view.output_buffer = ActionView::OutputBuffer.new
-    end
-  end
 end
diff --git a/actionview/test/template/controller_helper_test.rb b/actionview/test/template/controller_helper_test.rb
new file mode 100644
index 0000000000..b5e94ea4f1
--- /dev/null
+++ b/actionview/test/template/controller_helper_test.rb
@@ -0,0 +1,21 @@
+require 'abstract_unit'
+
+class ControllerHelperTest < ActionView::TestCase
+  tests ActionView::Helpers::ControllerHelper
+
+  class SpecializedFormBuilder < ActionView::Helpers::FormBuilder ; end
+
+  def test_assign_controller_sets_default_form_builder
+    @controller = OpenStruct.new(default_form_builder: SpecializedFormBuilder)
+    assign_controller(@controller)
+
+    assert_equal SpecializedFormBuilder, self.default_form_builder
+  end
+
+  def test_assign_controller_skips_default_form_builder
+    @controller = OpenStruct.new
+    assign_controller(@controller)
+
+    assert_nil self.default_form_builder
+  end
+end
diff --git a/actionview/test/template/date_helper_test.rb b/actionview/test/template/date_helper_test.rb
index bfb073680e..9212420ec9 100644
--- a/actionview/test/template/date_helper_test.rb
+++ b/actionview/test/template/date_helper_test.rb
@@ -130,7 +130,7 @@ class DateHelperTest < ActionView::TestCase
 
   def test_distance_in_words_with_mathn_required
     # test we avoid Integer#/ (redefined by mathn)
-    require 'mathn'
+    silence_warnings { require "mathn" }
     from = Time.utc(2004, 6, 6, 21, 45, 0)
     assert_distance_of_time_in_words(from)
   end
@@ -3217,12 +3217,4 @@ class DateHelperTest < ActionView::TestCase
     expected = '<time datetime="2013-02-20T00:00:00+00:00">20 Feb 00:00</time>'
     assert_equal expected, time_tag(time, :format => :short)
   end
-
-  protected
-    def with_env_tz(new_tz = 'US/Eastern')
-      old_tz, ENV['TZ'] = ENV['TZ'], new_tz
-      yield
-    ensure
-      old_tz ? ENV['TZ'] = old_tz : ENV.delete('TZ')
-    end
 end
diff --git a/actionview/test/template/dependency_tracker_test.rb b/actionview/test/template/dependency_tracker_test.rb
index bb375076c6..3ece9e50cd 100644
--- a/actionview/test/template/dependency_tracker_test.rb
+++ b/actionview/test/template/dependency_tracker_test.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 require 'abstract_unit'
 require 'action_view/dependency_tracker'
 
@@ -61,7 +59,6 @@ class ERBTrackerTest < Minitest::Test
   end
 
   def test_dependency_of_template_partial_with_layout
-    skip # FIXME: Needs to be fixed properly, right now we can only match one dependency per line. Need multiple!
     template = FakeTemplate.new("<%# render partial: 'messages/show', layout: 'messages/layout' %>", :erb)
     tracker = make_tracker("multiple/_dependencies", template)
 
diff --git a/actionview/test/template/digestor_test.rb b/actionview/test/template/digestor_test.rb
index c2b8439df3..dde757b5a2 100644
--- a/actionview/test/template/digestor_test.rb
+++ b/actionview/test/template/digestor_test.rb
@@ -1,5 +1,6 @@
 require 'abstract_unit'
 require 'fileutils'
+require 'action_view/dependency_tracker'
 
 class FixtureTemplate
   attr_reader :source, :handler
@@ -15,12 +16,13 @@ end
 class FixtureFinder
   FIXTURES_DIR = "#{File.dirname(__FILE__)}/../fixtures/digestor"
 
-  attr_reader   :details
+  attr_reader   :details, :view_paths
   attr_accessor :formats
   attr_accessor :variants
 
   def initialize
     @details  = {}
+    @view_paths = ActionView::PathSet.new(['digestor'])
     @formats  = []
     @variants = []
   end
@@ -75,6 +77,34 @@ class TemplateDigestorTest < ActionView::TestCase
     end
   end
 
+  def test_explicit_dependency_wildcard
+    assert_digest_difference("events/index") do
+      change_template("events/_completed")
+    end
+  end
+
+  def test_explicit_dependency_wildcard_picks_up_added_file
+    old_caching, ActionView::Resolver.caching = ActionView::Resolver.caching, false
+
+    assert_digest_difference("events/index") do
+      add_template("events/_uncompleted")
+    end
+  ensure
+    remove_template("events/_uncompleted")
+    ActionView::Resolver.caching = old_caching
+  end
+
+  def test_explicit_dependency_wildcard_picks_up_removed_file
+    old_caching, ActionView::Resolver.caching = ActionView::Resolver.caching, false
+    add_template("events/_subscribers_changed")
+
+    assert_digest_difference("events/index") do
+      remove_template("events/_subscribers_changed")
+    end
+  ensure
+    ActionView::Resolver.caching = old_caching
+  end
+
   def test_second_level_dependency
     assert_digest_difference("messages/show") do
       change_template("comments/_comments")
@@ -111,6 +141,18 @@ class TemplateDigestorTest < ActionView::TestCase
     end
   end
 
+  def test_logging_of_missing_template_for_dependencies
+    assert_logged "'messages/something_missing' file doesn't exist, so no dependencies" do
+      dependencies("messages/something_missing")
+    end
+  end
+
+  def test_logging_of_missing_template_for_nested_dependencies
+    assert_logged "'messages/something_missing' file doesn't exist, so no dependencies" do
+      nested_dependencies("messages/something_missing")
+    end
+  end
+
   def test_nested_template_directory
     assert_digest_difference("messages/show") do
       change_template("messages/actions/_move")
@@ -207,7 +249,7 @@ class TemplateDigestorTest < ActionView::TestCase
   end
 
   def test_variants
-    assert_digest_difference("messages/new", false, variants: [:iphone]) do
+    assert_digest_difference("messages/new", variants: [:iphone]) do
       change_template("messages/new",     :iphone)
       change_template("messages/_header", :iphone)
     end
@@ -227,16 +269,6 @@ class TemplateDigestorTest < ActionView::TestCase
     assert_not_equal digest_phone, digest_fridge_phone
   end
 
-  def test_cache_template_loading
-    resolver_before = ActionView::Resolver.caching
-    ActionView::Resolver.caching = false
-    assert_digest_difference("messages/edit", true) do
-      change_template("comments/_comment")
-    end
-  ensure
-    ActionView::Resolver.caching = resolver_before
-  end
-
   def test_digest_cache_cleanup_with_recursion
     first_digest = digest("level/_recursion")
     second_digest = digest("level/_recursion")
@@ -279,9 +311,9 @@ class TemplateDigestorTest < ActionView::TestCase
       end
     end
 
-    def assert_digest_difference(template_name, persistent = false, options = {})
+    def assert_digest_difference(template_name, options = {})
       previous_digest = digest(template_name, options)
-      ActionView::Digestor.cache.clear unless persistent
+      ActionView::Digestor.cache.clear
 
       yield
 
@@ -298,6 +330,14 @@ class TemplateDigestorTest < ActionView::TestCase
       ActionView::Digestor.digest({ name: template_name, finder: finder }.merge(options))
     end
 
+    def dependencies(template_name)
+      ActionView::Digestor.new({ name: template_name, finder: finder }).dependencies
+    end
+
+    def nested_dependencies(template_name)
+      ActionView::Digestor.new({ name: template_name, finder: finder }).nested_dependencies
+    end
+
     def finder
       @finder ||= FixtureFinder.new
     end
@@ -309,4 +349,9 @@ class TemplateDigestorTest < ActionView::TestCase
         f.write "\nTHIS WAS CHANGED!"
       end
     end
+    alias_method :add_template, :change_template
+
+    def remove_template(template_name)
+      File.delete("digestor/#{template_name}.html.erb")
+    end
 end
diff --git a/actionview/test/template/form_collections_helper_test.rb b/actionview/test/template/form_collections_helper_test.rb
index b193d387c3..b59be8e36c 100644
--- a/actionview/test/template/form_collections_helper_test.rb
+++ b/actionview/test/template/form_collections_helper_test.rb
@@ -198,6 +198,41 @@ class FormCollectionsHelperTest < ActionView::TestCase
     assert_select 'input[type=radio][value=false][checked=checked]'
   end
 
+  test 'collection radio buttons generates only one hidden field for the entire collection, to ensure something will be sent back to the server when posting an empty collection' do
+    collection = [Category.new(1, 'Category 1'), Category.new(2, 'Category 2')]
+    with_collection_radio_buttons :user, :category_ids, collection, :id, :name
+
+    assert_select "input[type=hidden][name='user[category_ids][]'][value='']", count: 1
+  end
+
+  test 'collection radio buttons generates a hidden field using the given :name in :html_options' do
+    collection = [Category.new(1, 'Category 1'), Category.new(2, 'Category 2')]
+    with_collection_radio_buttons :user, :category_ids, collection, :id, :name, {}, { name: "user[other_category_ids][]" }
+
+    assert_select "input[type=hidden][name='user[other_category_ids][]'][value='']", count: 1
+  end
+
+  test 'collection radio buttons generates a hidden field with index if it was provided' do
+    collection = [Category.new(1, 'Category 1'), Category.new(2, 'Category 2')]
+    with_collection_radio_buttons :user, :category_ids, collection, :id, :name, { index: 322 }
+
+    assert_select "input[type=hidden][name='user[322][category_ids][]'][value='']", count: 1
+  end
+
+  test 'collection radio buttons does not generate a hidden field if include_hidden option is false' do
+    collection = [Category.new(1, 'Category 1'), Category.new(2, 'Category 2')]
+    with_collection_radio_buttons :user, :category_ids, collection, :id, :name, include_hidden: false
+
+    assert_select "input[type=hidden][name='user[category_ids][]'][value='']", count: 0
+  end
+
+  test 'collection radio buttons does not generate a hidden field if include_hidden option is false with key as string' do
+    collection = [Category.new(1, 'Category 1'), Category.new(2, 'Category 2')]
+    with_collection_radio_buttons :user, :category_ids, collection, :id, :name, 'include_hidden' => false
+
+    assert_select "input[type=hidden][name='user[category_ids][]'][value='']", count: 0
+  end
+
   # COLLECTION CHECK BOXES
   test 'collection check boxes accepts a collection and generate a series of checkboxes for value method' do
     collection = [Category.new(1, 'Category 1'), Category.new(2, 'Category 2')]
@@ -235,6 +270,13 @@ class FormCollectionsHelperTest < ActionView::TestCase
     assert_select "input[type=hidden][name='user[category_ids][]'][value='']", :count => 0
   end
 
+  test 'collection check boxes does not generate a hidden field if include_hidden option is false with key as string' do
+    collection = [Category.new(1, 'Category 1'), Category.new(2, 'Category 2')]
+    with_collection_check_boxes :user, :category_ids, collection, :id, :name, 'include_hidden' => false
+
+    assert_select "input[type=hidden][name='user[category_ids][]'][value='']", count: 0
+  end
+
   test 'collection check boxes accepts a collection and generate a series of checkboxes with labels for label method' do
     collection = [Category.new(1, 'Category 1'), Category.new(2, 'Category 2')]
     with_collection_check_boxes :user, :category_ids, collection, :id, :name
@@ -264,6 +306,17 @@ class FormCollectionsHelperTest < ActionView::TestCase
     assert_select 'input[type=checkbox][value="2"].bar'
   end
 
+  test 'collection check boxes propagates input id to the label for attribute' do
+    collection = [[1, 'Category 1', {id: 'foo'}], [2, 'Category 2', {id: 'bar'}]]
+    with_collection_check_boxes :user, :active, collection, :first, :second
+
+    assert_select 'input[type=checkbox][value="1"]#foo'
+    assert_select 'input[type=checkbox][value="2"]#bar'
+
+    assert_select 'label[for=foo]'
+    assert_select 'label[for=bar]'
+  end
+
   test 'collection check boxes sets the label class defined inside the block' do
     collection = [[1, 'Category 1', {class: 'foo'}], [2, 'Category 2', {class: 'bar'}]]
     with_collection_check_boxes :user, :active, collection, :second, :first do |b|
diff --git a/actionview/test/template/form_helper_test.rb b/actionview/test/template/form_helper_test.rb
index e4fd797924..41f31f1582 100644
--- a/actionview/test/template/form_helper_test.rb
+++ b/actionview/test/template/form_helper_test.rb
@@ -40,6 +40,9 @@ class FormHelperTest < ActionView::TestCase
           },
           tag: {
             value: "Tag"
+          },
+          post_delegate: {
+            title: 'Delegate model_name title'
           }
         }
       }
@@ -81,6 +84,9 @@ class FormHelperTest < ActionView::TestCase
               body: "Write body here"
             }
           },
+          post_delegate: {
+            title: 'Delegate model_name title'
+          },
           tag: {
             value: "Tag"
           }
@@ -117,6 +123,10 @@ class FormHelperTest < ActionView::TestCase
     @post.tags = []
     @post.tags << Tag.new
 
+    @post_delegator = PostDelegator.new
+
+    @post_delegator.title = 'Hello World'
+
     @car = Car.new("#000FFF")
   end
 
@@ -249,6 +259,18 @@ class FormHelperTest < ActionView::TestCase
     end
   end
 
+  def test_label_with_non_active_record_object
+    form_for(OpenStruct.new(name:'ok'), as: 'person', url: 'an_url', html: { id: 'create-person' }) do |f|
+      f.label(:name)
+    end
+
+    expected = whole_form("an_url", "create-person", "new_person", method: "post") do
+      '<label for="person_name">Name</label>'
+    end
+
+    assert_dom_equal expected, output_buffer
+  end
+
   def test_label_with_for_attribute_as_symbol
     assert_dom_equal('<label for="my_for">Title</label>', label(:post, :title, nil, for: "my_for"))
   end
@@ -337,6 +359,22 @@ class FormHelperTest < ActionView::TestCase
     )
   end
 
+  def test_label_with_to_model
+    assert_dom_equal(
+      %{<label for="post_delegator_title">Delegate Title</label>},
+      label(:post_delegator, :title)
+    )
+  end
+
+  def test_label_with_to_model_and_overridden_model_name
+    with_locale :label do
+      assert_dom_equal(
+        %{<label for="post_delegator_title">Delegate model_name title</label>},
+        label(:post_delegator, :title)
+      )
+    end
+  end
+
   def test_text_field_placeholder_without_locales
     with_locale :placeholder do
       assert_dom_equal('<input id="post_body" name="post[body]" placeholder="Body" type="text" value="Back to the hill and over it again!" />', text_field(:post, :body, placeholder: true))
@@ -349,12 +387,28 @@ class FormHelperTest < ActionView::TestCase
     end
   end
 
+  def test_text_field_placeholder_with_locales_and_to_model
+    with_locale :placeholder do
+      assert_dom_equal(
+        '<input id="post_delegator_title" name="post_delegator[title]" placeholder="Delegate model_name title" type="text" value="Hello World" />',
+        text_field(:post_delegator, :title, placeholder: true)
+      )
+    end
+  end
+
   def test_text_field_placeholder_with_human_attribute_name
     with_locale :placeholder do
       assert_dom_equal('<input id="post_cost" name="post[cost]" placeholder="Total cost" type="text" />', text_field(:post, :cost, placeholder: true))
     end
   end
 
+  def test_text_field_placeholder_with_human_attribute_name_and_to_model
+    assert_dom_equal(
+      '<input id="post_delegator_title" name="post_delegator[title]" placeholder="Delegate Title" type="text" value="Hello World" />',
+      text_field(:post_delegator, :title, placeholder: true)
+    )
+  end
+
   def test_text_field_placeholder_with_string_value
     with_locale :placeholder do
       assert_dom_equal('<input id="post_cost" name="post[cost]" placeholder="HOW MUCH?" type="text" />', text_field(:post, :cost, placeholder: "HOW MUCH?"))
@@ -910,7 +964,11 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_inputs_dont_use_before_type_cast_when_value_did_not_come_from_user
-    def @post.id_came_from_user?; false; end
+    class << @post
+      undef id_came_from_user?
+      def id_came_from_user?; false; end
+    end
+
     assert_dom_equal(
       %{<textarea id="post_id" name="post[id]">\n0</textarea>},
       text_area("post", "id")
@@ -1519,7 +1577,7 @@ class FormHelperTest < ActionView::TestCase
       "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" +
       "<input name='post[secret]' type='hidden' value='0' />" +
       "<input name='post[secret]' checked='checked' type='checkbox' id='post_secret' value='1' />" +
-      "<input name='commit' type='submit' value='Create post' />" +
+      "<input name='commit' data-disable-with='Create post' type='submit' value='Create post' />" +
       "<button name='button' type='submit'>Create post</button>" +
       "<button name='button' type='submit'><span>Create post</span></button>"
     end
@@ -1538,7 +1596,8 @@ class FormHelperTest < ActionView::TestCase
       "<input id='post_active_true' name='post[active]' type='radio' value='true' />" +
       "<label for='post_active_true'>true</label>" +
       "<input checked='checked' id='post_active_false' name='post[active]' type='radio' value='false' />" +
-      "<label for='post_active_false'>false</label>"
+      "<label for='post_active_false'>false</label>" +
+      "<input type='hidden' name='post[active][]' value='' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1561,7 +1620,8 @@ class FormHelperTest < ActionView::TestCase
       "true</label>" +
       "<label for='post_active_false'>"+
       "<input checked='checked' id='post_active_false' name='post[active]' type='radio' value='false' />" +
-      "false</label>"
+      "false</label>" +
+      "<input type='hidden' name='post[active][]' value='' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1587,6 +1647,7 @@ class FormHelperTest < ActionView::TestCase
       "<label for='post_active_false'>"+
       "<input checked='checked' id='post_active_false' name='post[active]' type='radio' value='false' />" +
       "false</label>"+
+      "<input type='hidden' name='post[active][]' value='' />" +
       "<input id='post_id' name='post[id]' type='hidden' value='1' />"
     end
 
@@ -1605,7 +1666,8 @@ class FormHelperTest < ActionView::TestCase
       "<input id='foo_post_active_true' name='post[active]' type='radio' value='true' />" +
       "<label for='foo_post_active_true'>true</label>" +
       "<input checked='checked' id='foo_post_active_false' name='post[active]' type='radio' value='false' />" +
-      "<label for='foo_post_active_false'>false</label>"
+      "<label for='foo_post_active_false'>false</label>" +
+      "<input type='hidden' name='post[active][]' value='' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1623,7 +1685,8 @@ class FormHelperTest < ActionView::TestCase
       "<input id='post_1_active_true' name='post[1][active]' type='radio' value='true' />" +
       "<label for='post_1_active_true'>true</label>" +
       "<input checked='checked' id='post_1_active_false' name='post[1][active]' type='radio' value='false' />" +
-      "<label for='post_1_active_false'>false</label>"
+      "<label for='post_1_active_false'>false</label>" +
+      "<input type='hidden' name='post[1][active][]' value='' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1796,7 +1859,7 @@ class FormHelperTest < ActionView::TestCase
 
     expected = whole_form("/posts/44", "edit_post_44", "edit_post", method: "patch") do
       "<input name='post[title]' type='text' id='post_title' value='And his name will be forty and four.' />" +
-      "<input name='commit' type='submit' value='Edit post' />"
+      "<input name='commit' data-disable-with='Edit post' type='submit' value='Edit post' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1817,7 +1880,7 @@ class FormHelperTest < ActionView::TestCase
       "<textarea name='other_name[body]' id='other_name_body'>\nBack to the hill and over it again!</textarea>" +
       "<input name='other_name[secret]' value='0' type='hidden' />" +
       "<input name='other_name[secret]' checked='checked' id='other_name_secret' value='1' type='checkbox' />" +
-      "<input name='commit' value='Create post' type='submit' />"
+      "<input name='commit' value='Create post' data-disable-with='Create post' type='submit' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1945,21 +2008,22 @@ class FormHelperTest < ActionView::TestCase
 
   def test_form_for_with_remote_without_html
     @post.persisted = false
-    @post.stubs(:to_key).returns(nil)
-    form_for(@post, remote: true) do |f|
-      concat f.text_field(:title)
-      concat f.text_area(:body)
-      concat f.check_box(:secret)
-    end
+    @post.stub(:to_key, nil) do
+      form_for(@post, remote: true) do |f|
+        concat f.text_field(:title)
+        concat f.text_area(:body)
+        concat f.check_box(:secret)
+      end
 
-    expected =  whole_form("/posts", "new_post", "new_post", remote: true) do
-      "<input name='post[title]' type='text' id='post_title' value='Hello World' />" +
-      "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" +
-      "<input name='post[secret]' type='hidden' value='0' />" +
-      "<input name='post[secret]' checked='checked' type='checkbox' id='post_secret' value='1' />"
-    end
+      expected =  whole_form("/posts", "new_post", "new_post", remote: true) do
+        "<input name='post[title]' type='text' id='post_title' value='Hello World' />" +
+        "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" +
+        "<input name='post[secret]' type='hidden' value='0' />" +
+        "<input name='post[secret]' checked='checked' type='checkbox' id='post_secret' value='1' />"
+      end
 
-    assert_dom_equal expected, output_buffer
+      assert_dom_equal expected, output_buffer
+    end
   end
 
   def test_form_for_without_object
@@ -2025,7 +2089,7 @@ class FormHelperTest < ActionView::TestCase
     expected = whole_form('/posts/123', 'edit_post_123', 'edit_post', method: 'patch') do
       "<div class='field_with_errors'><label for='post_author_name' class='label'>Author name</label></div>" +
       "<div class='field_with_errors'><input name='post[author_name]' type='text' id='post_author_name' value='' /></div>" +
-      "<input name='commit' type='submit' value='Create post' />"
+      "<input name='commit' data-disable-with='Create post' type='submit' value='Create post' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -2043,7 +2107,7 @@ class FormHelperTest < ActionView::TestCase
     expected = whole_form('/posts/123', 'edit_post_123', 'edit_post', method: 'patch') do
       "<div class='field_with_errors'><label for='post_author_name' class='label'>Author name</label></div>" +
       "<div class='field_with_errors'><input name='post[author_name]' type='text' id='post_author_name' value='' /></div>" +
-      "<input name='commit' type='submit' value='Create post' />"
+      "<input name='commit' data-disable-with='Create post' type='submit' value='Create post' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -2162,16 +2226,17 @@ class FormHelperTest < ActionView::TestCase
   def test_submit_with_object_as_new_record_and_locale_strings
     with_locale :submit do
       @post.persisted = false
-      @post.stubs(:to_key).returns(nil)
-      form_for(@post) do |f|
-        concat f.submit
-      end
+      @post.stub(:to_key, nil) do
+        form_for(@post) do |f|
+          concat f.submit
+        end
 
-      expected = whole_form('/posts', 'new_post', 'new_post') do
-        "<input name='commit' type='submit' value='Create Post' />"
-      end
+        expected = whole_form('/posts', 'new_post', 'new_post') do
+          "<input name='commit' data-disable-with='Create Post' type='submit' value='Create Post' />"
+        end
 
-      assert_dom_equal expected, output_buffer
+        assert_dom_equal expected, output_buffer
+      end
     end
   end
 
@@ -2182,7 +2247,7 @@ class FormHelperTest < ActionView::TestCase
       end
 
       expected = whole_form('/posts/123', 'edit_post_123', 'edit_post', method: 'patch') do
-        "<input name='commit' type='submit' value='Confirm Post changes' />"
+      "<input name='commit' data-disable-with='Confirm Post changes' type='submit' value='Confirm Post changes' />"
       end
 
       assert_dom_equal expected, output_buffer
@@ -2196,7 +2261,7 @@ class FormHelperTest < ActionView::TestCase
       end
 
       expected = whole_form do
-        "<input name='commit' class='extra' type='submit' value='Save changes' />"
+      "<input name='commit' class='extra' data-disable-with='Save changes' type='submit' value='Save changes' />"
       end
 
       assert_dom_equal expected, output_buffer
@@ -2210,7 +2275,7 @@ class FormHelperTest < ActionView::TestCase
       end
 
       expected = whole_form('/posts/123', 'edit_another_post', 'edit_another_post', method: 'patch') do
-        "<input name='commit' type='submit' value='Update your Post' />"
+      "<input name='commit' data-disable-with='Update your Post' type='submit' value='Update your Post' />"
       end
 
       assert_dom_equal expected, output_buffer
@@ -2232,6 +2297,27 @@ class FormHelperTest < ActionView::TestCase
     assert_dom_equal expected, output_buffer
   end
 
+  def test_deep_nested_fields_for
+    @comment.save
+    form_for(:posts) do |f|
+      f.fields_for('post[]', @post) do |f2|
+        f2.text_field(:id)
+        @post.comments.each do |comment|
+          concat f2.fields_for('comment[]', comment) { |c|
+            concat c.text_field(:name)
+          }
+        end
+      end
+    end
+
+    expected = whole_form do
+      "<input name='posts[post][0][comment][1][name]' type='text' id='posts_post_0_comment_1_name' value='comment #1' />"
+    end
+
+    assert_dom_equal expected, output_buffer
+  end
+
+
   def test_nested_fields_for_with_nested_collections
     form_for(@post, as: 'post[]') do |f|
       concat f.text_field(:title)
@@ -2749,11 +2835,12 @@ class FormHelperTest < ActionView::TestCase
   def test_nested_fields_label_translation_with_more_than_10_records
     @post.comments = Array.new(11) { |id| Comment.new(id + 1) }
 
-    I18n.expects(:t).with('post.comments.body', default: [:"comment.body", ''], scope: "helpers.label").times(11).returns "Write body here"
-
-    form_for(@post) do |f|
-      f.fields_for(:comments) do |cf|
-        concat cf.label(:body)
+    params = 11.times.map { ['post.comments.body', default: [:"comment.body", ''], scope: "helpers.label"] }
+    assert_called_with(I18n, :t, params, returns: "Write body here") do
+      form_for(@post) do |f|
+        f.fields_for(:comments) do |cf|
+          concat cf.label(:body)
+        end
       end
     end
   end
@@ -2820,6 +2907,23 @@ class FormHelperTest < ActionView::TestCase
     assert_dom_equal expected, output_buffer
   end
 
+  def test_nested_fields_for_with_child_index_as_lambda_option_override_on_a_nested_attributes_collection_association
+    @post.comments = []
+
+    form_for(@post) do |f|
+      concat f.fields_for(:comments, Comment.new(321), child_index: -> { 'abc' } ) { |cf|
+        concat cf.text_field(:name)
+      }
+    end
+
+    expected = whole_form('/posts/123', 'edit_post_123', 'edit_post', method: 'patch') do
+      '<input id="post_comments_attributes_abc_name" name="post[comments_attributes][abc][name]" type="text" value="comment #321" />' +
+      '<input id="post_comments_attributes_abc_id" name="post[comments_attributes][abc][id]" type="hidden" value="321" />'
+    end
+
+    assert_dom_equal expected, output_buffer
+  end
+
   class FakeAssociationProxy
     def to_ary
       [1, 2, 3]
@@ -3194,6 +3298,30 @@ class FormHelperTest < ActionView::TestCase
     ActionView::Base.default_form_builder = old_default_form_builder
   end
 
+  def test_form_builder_override
+    self.default_form_builder = LabelledFormBuilder
+
+    output_buffer = fields_for(:post, @post) do |f|
+      concat f.text_field(:title)
+    end
+
+    expected = "<label for='title'>Title:</label> <input name='post[title]' type='text' id='post_title' value='Hello World' /><br/>"
+
+    assert_dom_equal expected, output_buffer
+  end
+
+  def test_lazy_loading_form_builder_override
+    self.default_form_builder = "FormHelperTest::LabelledFormBuilder"
+
+    output_buffer = fields_for(:post, @post) do |f|
+      concat f.text_field(:title)
+    end
+
+    expected = "<label for='title'>Title:</label> <input name='post[title]' type='text' id='post_title' value='Hello World' /><br/>"
+
+    assert_dom_equal expected, output_buffer
+  end
+
   def test_fields_for_with_labelled_builder
     output_buffer = fields_for(:post, @post, builder: LabelledFormBuilder) do |f|
       concat f.text_field(:title)
diff --git a/actionview/test/template/form_options_helper_i18n_test.rb b/actionview/test/template/form_options_helper_i18n_test.rb
index 4972ea6511..26ede09a5f 100644
--- a/actionview/test/template/form_options_helper_i18n_test.rb
+++ b/actionview/test/template/form_options_helper_i18n_test.rb
@@ -14,8 +14,9 @@ class FormOptionsHelperI18nTests < ActionView::TestCase
   end
 
   def test_select_with_prompt_true_translates_prompt_message
-    I18n.expects(:translate).with('helpers.select.prompt', { :default => 'Please select' })
-    select('post', 'category', [], :prompt => true)
+    assert_called_with(I18n, :translate, ['helpers.select.prompt', { :default => 'Please select' }]) do
+      select('post', 'category', [], :prompt => true)
+    end
   end
 
   def test_select_with_translated_prompt
diff --git a/actionview/test/template/form_options_helper_test.rb b/actionview/test/template/form_options_helper_test.rb
index d25fa3706f..d7daba8bf3 100644
--- a/actionview/test/template/form_options_helper_test.rb
+++ b/actionview/test/template/form_options_helper_test.rb
@@ -645,6 +645,13 @@ class FormOptionsHelperTest < ActionView::TestCase
     )
   end
 
+  def test_select_with_include_blank_false_and_required
+    @post = Post.new
+    @post.category = "<mus>"
+    e = assert_raises(ArgumentError) { select("post", "category", %w( abe <mus> hest), { include_blank: false }, required: 'required') }
+    assert_match(/include_blank cannot be false for a required field./, e.message)
+  end
+
   def test_select_with_blank_as_string
     @post = Post.new
     @post.category = "<mus>"
diff --git a/actionview/test/template/form_tag_helper_test.rb b/actionview/test/template/form_tag_helper_test.rb
index 84a581b107..de1eb89dc5 100644
--- a/actionview/test/template/form_tag_helper_test.rb
+++ b/actionview/test/template/form_tag_helper_test.rb
@@ -64,6 +64,18 @@ class FormTagHelperTest < ActionView::TestCase
     assert_dom_equal expected, actual
   end
 
+  def test_check_box_tag_disabled
+    actual = check_box_tag "admin","1", false, disabled: true
+    expected = %(<input id="admin" disabled="disabled" name="admin" type="checkbox" value="1" />)
+    assert_dom_equal expected, actual
+  end
+
+  def test_check_box_tag_default_checked
+    actual = check_box_tag "admin","1", true
+    expected = %(<input id="admin" checked="checked" name="admin" type="checkbox" value="1" />)
+    assert_dom_equal expected, actual
+  end
+
   def test_check_box_tag_id_sanitized
     label_elem = root_elem(check_box_tag("project[2][admin]"))
     assert_match VALID_HTML_ID, label_elem['id']
@@ -210,13 +222,13 @@ class FormTagHelperTest < ActionView::TestCase
   end
 
   def test_select_tag_with_multiple
-    actual = select_tag "colors", "<option>Red</option><option>Blue</option><option>Green</option>".html_safe, :multiple => :true
-    expected = %(<select id="colors" multiple="multiple" name="colors"><option>Red</option><option>Blue</option><option>Green</option></select>)
+    actual = select_tag "colors", "<option>Red</option><option>Blue</option><option>Green</option>".html_safe, multiple: true
+    expected = %(<select id="colors" multiple="multiple" name="colors[]"><option>Red</option><option>Blue</option><option>Green</option></select>)
     assert_dom_equal expected, actual
   end
 
   def test_select_tag_disabled
-    actual = select_tag "places", "<option>Home</option><option>Work</option><option>Pub</option>".html_safe, :disabled => :true
+    actual = select_tag "places", "<option>Home</option><option>Work</option><option>Pub</option>".html_safe, disabled: true
     expected = %(<select id="places" disabled="disabled" name="places"><option>Home</option><option>Work</option><option>Pub</option></select>)
     assert_dom_equal expected, actual
   end
@@ -351,12 +363,18 @@ class FormTagHelperTest < ActionView::TestCase
     assert_dom_equal expected, actual
   end
 
-  def test_text_field_disabled
-    actual = text_field_tag "title", "Hello!", :disabled => :true
+  def test_text_field_tag_disabled
+    actual = text_field_tag "title", "Hello!", disabled: true
     expected = %(<input id="title" name="title" disabled="disabled" type="text" value="Hello!" />)
     assert_dom_equal expected, actual
   end
 
+  def test_text_field_tag_with_placeholder_option
+    actual = text_field_tag "title", "Hello!", placeholder: 'Enter search term...'
+    expected = %(<input id="title" name="title" placeholder="Enter search term..." type="text" value="Hello!" />)
+    assert_dom_equal expected, actual
+  end
+
   def test_text_field_tag_with_multiple_options
     actual = text_field_tag "title", "Hello!", :size => 70, :maxlength => 80
     expected = %(<input id="title" name="title" size="70" maxlength="80" type="text" value="Hello!" />)
@@ -433,6 +451,44 @@ class FormTagHelperTest < ActionView::TestCase
     )
   end
 
+  def test_empty_submit_tag
+    assert_dom_equal(
+      %(<input data-disable-with="Save" name='commit' type="submit" value="Save" />),
+      submit_tag("Save")
+    )
+  end
+
+  def test_empty_submit_tag_with_opt_out
+    ActionView::Base.automatically_disable_submit_tag = false
+    assert_dom_equal(
+      %(<input name='commit' type="submit" value="Save" />),
+      submit_tag("Save")
+    )
+  ensure
+    ActionView::Base.automatically_disable_submit_tag = true
+  end
+
+  def test_submit_tag_having_data_disable_with_string
+    assert_dom_equal(
+      %(<input data-disable-with="Processing..." data-confirm="Are you sure?" name='commit' type="submit" value="Save" />),
+      submit_tag("Save", { "data-disable-with" => "Processing...", "data-confirm" => "Are you sure?" })
+    )
+  end
+
+  def test_submit_tag_having_data_disable_with_boolean
+    assert_dom_equal(
+      %(<input data-confirm="Are you sure?" name='commit' type="submit" value="Save" />),
+      submit_tag("Save", { "data-disable-with" => false, "data-confirm" => "Are you sure?" })
+    )
+  end
+
+  def test_submit_tag_having_data_hash_disable_with_boolean
+    assert_dom_equal(
+      %(<input data-confirm="Are you sure?" name='commit' type="submit" value="Save" />),
+      submit_tag("Save", { :data => { :confirm => "Are you sure?", :disable_with => false } })
+    )
+  end
+
   def test_submit_tag_with_no_onclick_options
     assert_dom_equal(
       %(<input name='commit' data-disable-with="Saving..." type="submit" value="Save" />),
@@ -442,11 +498,19 @@ class FormTagHelperTest < ActionView::TestCase
 
   def test_submit_tag_with_confirmation
     assert_dom_equal(
-      %(<input name='commit' type='submit' value='Save' data-confirm="Are you sure?" />),
+      %(<input name='commit' type='submit' value='Save' data-confirm="Are you sure?" data-disable-with="Save" />),
       submit_tag("Save", :data => { :confirm => "Are you sure?" })
     )
   end
 
+  def test_submit_tag_doesnt_have_data_disable_with_twice
+    assert_equal(
+      %(<input type="submit" name="commit" value="Save" data-confirm="Are you sure?" data-disable-with="Processing..." />),
+      submit_tag("Save", { "data-disable-with" => "Processing...", "data-confirm" => "Are you sure?" })
+    )
+  end
+
+
   def test_button_tag
     assert_dom_equal(
       %(<button name="button" type="submit">Button</button>),
@@ -510,6 +574,13 @@ class FormTagHelperTest < ActionView::TestCase
     )
   end
 
+  def test_button_tag_with_data_disable_with_option
+    assert_dom_equal(
+      %(<button name="button" type="submit" data-disable-with="Please wait...">Checkout</button>),
+      button_tag("Checkout", data: { disable_with: "Please wait..." })
+    )
+  end
+
   def test_image_submit_tag_with_confirmation
     assert_dom_equal(
       %(<input alt="Save" type="image" src="/images/save.gif" data-confirm="Are you sure?" />),
diff --git a/actionview/test/template/javascript_helper_test.rb b/actionview/test/template/javascript_helper_test.rb
index 9ba7f64ad1..9f1535ef53 100644
--- a/actionview/test/template/javascript_helper_test.rb
+++ b/actionview/test/template/javascript_helper_test.rb
@@ -3,14 +3,7 @@ require 'abstract_unit'
 class JavaScriptHelperTest < ActionView::TestCase
   tests ActionView::Helpers::JavaScriptHelper
 
-  def _evaluate_assigns_and_ivars() end
-
-  attr_accessor :formats, :output_buffer
-
-  def update_details(details)
-    @details = details
-    yield if block_given?
-  end
+  attr_accessor :output_buffer
 
   setup do
     @old_escape_html_entities_in_json = ActiveSupport.escape_html_entities_in_json
diff --git a/actionview/test/template/lookup_context_test.rb b/actionview/test/template/lookup_context_test.rb
index 4f7823045e..2e3a3f9bae 100644
--- a/actionview/test/template/lookup_context_test.rb
+++ b/actionview/test/template/lookup_context_test.rb
@@ -27,7 +27,7 @@ class LookupContextTest < ActiveSupport::TestCase
   end
 
   test "normalizes details on initialization" do
-    assert_equal Mime::SET, @lookup_context.formats
+    assert_equal Mime::SET.to_a, @lookup_context.formats
     assert_equal :en, @lookup_context.locale
   end
 
@@ -48,7 +48,7 @@ class LookupContextTest < ActiveSupport::TestCase
 
   test "handles */* formats" do
     @lookup_context.formats = ["*/*"]
-    assert_equal Mime::SET, @lookup_context.formats
+    assert_equal Mime::SET.to_a, @lookup_context.formats
   end
 
   test "handles explicitly defined */* formats fallback to :js" do
@@ -108,10 +108,11 @@ class LookupContextTest < ActiveSupport::TestCase
   end
 
   test "found templates respects given formats if one cannot be found from template or handler" do
-    ActionView::Template::Handlers::Builder.expects(:default_format).returns(nil)
-    @lookup_context.formats = [:text]
-    template = @lookup_context.find("hello", %w(test))
-    assert_equal [:text], template.formats
+    assert_called(ActionView::Template::Handlers::Builder, :default_format, returns: nil) do
+      @lookup_context.formats = [:text]
+      template = @lookup_context.find("hello", %w(test))
+      assert_equal [:text], template.formats
+    end
   end
 
   test "adds fallbacks to view paths when required" do
@@ -210,45 +211,50 @@ end
 class LookupContextWithFalseCaching < ActiveSupport::TestCase
   def setup
     @resolver = ActionView::FixtureResolver.new("test/_foo.erb" => ["Foo", Time.utc(2000)])
-    ActionView::Resolver.stubs(:caching?).returns(false)
     @lookup_context = ActionView::LookupContext.new(@resolver, {})
   end
 
   test "templates are always found in the resolver but timestamp is checked before being compiled" do
-    template = @lookup_context.find("foo", %w(test), true)
-    assert_equal "Foo", template.source
-
-    # Now we are going to change the template, but it won't change the returned template
-    # since the timestamp is the same.
-    @resolver.hash["test/_foo.erb"][0] = "Bar"
-    template = @lookup_context.find("foo", %w(test), true)
-    assert_equal "Foo", template.source
-
-    # Now update the timestamp.
-    @resolver.hash["test/_foo.erb"][1] = Time.now.utc
-    template = @lookup_context.find("foo", %w(test), true)
-    assert_equal "Bar", template.source
+    ActionView::Resolver.stub(:caching?, false) do
+      template = @lookup_context.find("foo", %w(test), true)
+      assert_equal "Foo", template.source
+
+      # Now we are going to change the template, but it won't change the returned template
+      # since the timestamp is the same.
+      @resolver.hash["test/_foo.erb"][0] = "Bar"
+      template = @lookup_context.find("foo", %w(test), true)
+      assert_equal "Foo", template.source
+
+      # Now update the timestamp.
+      @resolver.hash["test/_foo.erb"][1] = Time.now.utc
+      template = @lookup_context.find("foo", %w(test), true)
+      assert_equal "Bar", template.source
+    end
   end
 
   test "if no template was found in the second lookup, with no cache, raise error" do
-    template = @lookup_context.find("foo", %w(test), true)
-    assert_equal "Foo", template.source
+    ActionView::Resolver.stub(:caching?, false) do
+      template = @lookup_context.find("foo", %w(test), true)
+      assert_equal "Foo", template.source
 
-    @resolver.hash.clear
-    assert_raise ActionView::MissingTemplate do
-      @lookup_context.find("foo", %w(test), true)
+      @resolver.hash.clear
+      assert_raise ActionView::MissingTemplate do
+        @lookup_context.find("foo", %w(test), true)
+      end
     end
   end
 
   test "if no template was cached in the first lookup, retrieval should work in the second call" do
-    @resolver.hash.clear
-    assert_raise ActionView::MissingTemplate do
-      @lookup_context.find("foo", %w(test), true)
-    end
+    ActionView::Resolver.stub(:caching?, false) do
+      @resolver.hash.clear
+      assert_raise ActionView::MissingTemplate do
+        @lookup_context.find("foo", %w(test), true)
+      end
 
-    @resolver.hash["test/_foo.erb"] = ["Foo", Time.utc(2000)]
-    template = @lookup_context.find("foo", %w(test), true)
-    assert_equal "Foo", template.source
+      @resolver.hash["test/_foo.erb"] = ["Foo", Time.utc(2000)]
+      template = @lookup_context.find("foo", %w(test), true)
+      assert_equal "Foo", template.source
+    end
   end
 end
 
diff --git a/actionview/test/template/number_helper_test.rb b/actionview/test/template/number_helper_test.rb
index b59883b760..ace3e950b8 100644
--- a/actionview/test/template/number_helper_test.rb
+++ b/actionview/test/template/number_helper_test.rb
@@ -21,6 +21,7 @@ class NumberHelperTest < ActionView::TestCase
     assert_equal "&lt;b&gt;1,234,567,890.50&lt;/b&gt; $", number_to_currency("1234567890.50", format: "<b>%n</b> %u")
     assert_equal "&lt;b&gt;1,234,567,890.50&lt;/b&gt; $", number_to_currency("-1234567890.50", negative_format: "<b>%n</b> %u")
     assert_equal "&lt;b&gt;1,234,567,890.50&lt;/b&gt; $", number_to_currency("-1234567890.50", 'negative_format' => "<b>%n</b> %u")
+    assert_equal '₹ 12,30,000.00', number_to_currency(1230000, delimiter_pattern: /(\d+?)(?=(\d\d)+(\d)(?!\d))/, unit: '₹', format: "%u %n")
   end
 
   def test_number_to_percentage
@@ -35,6 +36,10 @@ class NumberHelperTest < ActionView::TestCase
     assert_equal "98a%", number_to_percentage("98a")
     assert_equal "NaN%", number_to_percentage(Float::NAN)
     assert_equal "Inf%", number_to_percentage(Float::INFINITY)
+    assert_equal "NaN%", number_to_percentage(Float::NAN, precision: 0)
+    assert_equal "Inf%", number_to_percentage(Float::INFINITY, precision: 0)
+    assert_equal "NaN%", number_to_percentage(Float::NAN, precision: 1)
+    assert_equal "Inf%", number_to_percentage(Float::INFINITY, precision: 1)
   end
 
   def test_number_with_delimiter
diff --git a/actionview/test/template/record_tag_helper_test.rb b/actionview/test/template/record_tag_helper_test.rb
index ab84bccb56..bfc5d04bed 100644
--- a/actionview/test/template/record_tag_helper_test.rb
+++ b/actionview/test/template/record_tag_helper_test.rb
@@ -2,7 +2,7 @@ require 'abstract_unit'
 
 class RecordTagPost
   extend ActiveModel::Naming
-  include ActiveModel::Conversion
+
   attr_accessor :id, :body
 
   def initialize
@@ -14,7 +14,6 @@ class RecordTagPost
 end
 
 class RecordTagHelperTest < ActionView::TestCase
-  include RenderERBUtils
 
   tests ActionView::Helpers::RecordTagHelper
 
@@ -24,94 +23,10 @@ class RecordTagHelperTest < ActionView::TestCase
   end
 
   def test_content_tag_for
-    expected = %(<li class="record_tag_post" id="record_tag_post_45"></li>)
-    actual = content_tag_for(:li, @post)
-    assert_dom_equal expected, actual
-  end
-
-  def test_content_tag_for_prefix
-    expected = %(<ul class="archived_record_tag_post" id="archived_record_tag_post_45"></ul>)
-    actual = content_tag_for(:ul, @post, :archived)
-    assert_dom_equal expected, actual
-  end
-
-  def test_content_tag_for_with_extra_html_options
-    expected = %(<tr class="record_tag_post special" id="record_tag_post_45" style='background-color: #f0f0f0'></tr>)
-    actual = content_tag_for(:tr, @post, class: "special", style: "background-color: #f0f0f0")
-    assert_dom_equal expected, actual
-  end
-
-  def test_content_tag_for_with_array_css_class
-    expected = %(<tr class="record_tag_post special odd" id="record_tag_post_45"></tr>)
-    actual = content_tag_for(:tr, @post, class: ["special", "odd"])
-    assert_dom_equal expected, actual
-  end
-
-  def test_content_tag_for_with_prefix_and_extra_html_options
-    expected = %(<tr class="archived_record_tag_post special" id="archived_record_tag_post_45" style='background-color: #f0f0f0'></tr>)
-    actual = content_tag_for(:tr, @post, :archived, class: "special", style: "background-color: #f0f0f0")
-    assert_dom_equal expected, actual
-  end
-
-  def test_block_not_in_erb_multiple_calls
-    expected = %(<div class="record_tag_post special" id="record_tag_post_45">What a wonderful world!</div>)
-    actual = div_for(@post, class: "special") { @post.body }
-    assert_dom_equal expected, actual
-    actual = div_for(@post, class: "special") { @post.body }
-    assert_dom_equal expected, actual
-  end
-
-  def test_block_works_with_content_tag_for_in_erb
-    expected = %(<tr class="record_tag_post" id="record_tag_post_45">What a wonderful world!</tr>)
-    actual = render_erb("<%= content_tag_for(:tr, @post) do %><%= @post.body %><% end %>")
-    assert_dom_equal expected, actual
-  end
-
-  def test_div_for_in_erb
-    expected = %(<div class="record_tag_post special" id="record_tag_post_45">What a wonderful world!</div>)
-    actual = render_erb("<%= div_for(@post, class: 'special') do %><%= @post.body %><% end %>")
-    assert_dom_equal expected, actual
-  end
-
-  def test_content_tag_for_collection
-    post_1 = RecordTagPost.new { |post| post.id = 101; post.body = "Hello!" }
-    post_2 = RecordTagPost.new { |post| post.id = 102; post.body = "World!" }
-    expected = %(<li class="record_tag_post" id="record_tag_post_101">Hello!</li>\n<li class="record_tag_post" id="record_tag_post_102">World!</li>)
-    actual = content_tag_for(:li, [post_1, post_2]) { |post| post.body }
-    assert_dom_equal expected, actual
-  end
-
-  def test_content_tag_for_collection_without_given_block
-    post_1 = RecordTagPost.new.tap { |post| post.id = 101; post.body = "Hello!" }
-    post_2 = RecordTagPost.new.tap { |post| post.id = 102; post.body = "World!" }
-    expected = %(<li class="record_tag_post" id="record_tag_post_101"></li>\n<li class="record_tag_post" id="record_tag_post_102"></li>)
-    actual = content_tag_for(:li, [post_1, post_2])
-    assert_dom_equal expected, actual
-  end
-
-  def test_div_for_collection
-    post_1 = RecordTagPost.new { |post| post.id = 101; post.body = "Hello!" }
-    post_2 = RecordTagPost.new { |post| post.id = 102; post.body = "World!" }
-    expected = %(<div class="record_tag_post" id="record_tag_post_101">Hello!</div>\n<div class="record_tag_post" id="record_tag_post_102">World!</div>)
-    actual = div_for([post_1, post_2]) { |post| post.body }
-    assert_dom_equal expected, actual
-  end
-
-  def test_content_tag_for_single_record_is_html_safe
-    result = div_for(@post, class: "special") { @post.body }
-    assert result.html_safe?
-  end
-
-  def test_content_tag_for_collection_is_html_safe
-    post_1 = RecordTagPost.new { |post| post.id = 101; post.body = "Hello!" }
-    post_2 = RecordTagPost.new { |post| post.id = 102; post.body = "World!" }
-    result = content_tag_for(:li, [post_1, post_2]) { |post| post.body }
-    assert result.html_safe?
+    assert_raises(NoMethodError) { content_tag_for(:li, @post) }
   end
 
-  def test_content_tag_for_does_not_change_options_hash
-    options = { class: "important" }
-    content_tag_for(:li, @post, options)
-    assert_equal({ class: "important" }, options)
+  def test_div_for
+    assert_raises(NoMethodError) { div_for(@post, class: "special") }
   end
 end
diff --git a/actionview/test/template/render_test.rb b/actionview/test/template/render_test.rb
index dc4abca048..00fc28a522 100644
--- a/actionview/test/template/render_test.rb
+++ b/actionview/test/template/render_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'controller/fake_models'
 
@@ -8,7 +7,10 @@ end
 module RenderTestCases
   def setup_view(paths)
     @assigns = { :secret => 'in the sauce' }
-    @view = ActionView::Base.new(paths, @assigns)
+    @view = Class.new(ActionView::Base) do
+      def view_cache_dependencies; end
+    end.new(paths, @assigns)
+
     @controller_view = TestController.new.view_context
 
     # Reload and register danish language for testing
@@ -62,9 +64,10 @@ module RenderTestCases
 
   def test_render_template_with_a_missing_partial_of_another_format
     @view.lookup_context.formats = [:html]
-    assert_raise ActionView::Template::Error, "Missing partial /_missing with {:locale=>[:en], :formats=>[:json], :handlers=>[:erb, :builder]}" do
+    e = assert_raise ActionView::Template::Error do
       @view.render(:template => "with_format", :formats => [:json])
     end
+    assert_includes(e.message, "Missing partial /_missing with {:locale=>[:en], :formats=>[:json], :variants=>[], :handlers=>[:raw, :erb, :builder, :ruby]}.")
   end
 
   def test_render_file_with_locale
@@ -172,18 +175,12 @@ module RenderTestCases
     assert_equal "only partial", @view.render("test/partial_only", :counter_counter => 5)
   end
 
-  def test_render_partial_with_invalid_name
-    e = assert_raises(ArgumentError) { @view.render(:partial => "test/200") }
-    assert_equal "The partial name (test/200) is not a valid Ruby identifier; " +
-      "make sure your partial name starts with underscore, " +
-      "and is followed by any combination of letters, numbers and underscores.", e.message
+  def test_render_partial_with_number
+    assert_nothing_raised { @view.render(:partial => "test/200") }
   end
 
   def test_render_partial_with_missing_filename
-    e = assert_raises(ArgumentError) { @view.render(:partial => "test/") }
-    assert_equal "The partial name (test/) is not a valid Ruby identifier; " +
-      "make sure your partial name starts with underscore, " +
-      "and is followed by any combination of letters, numbers and underscores.", e.message
+    assert_raises(ActionView::MissingTemplate) { @view.render(:partial => "test/") }
   end
 
   def test_render_partial_with_incompatible_object
@@ -191,11 +188,12 @@ module RenderTestCases
     assert_equal "'#{nil.inspect}' is not an ActiveModel-compatible object. It must implement :to_partial_path.", e.message
   end
 
+  def test_render_partial_starting_with_a_capital
+    assert_nothing_raised { @view.render(:partial => 'test/FooBar') }
+  end
+
   def test_render_partial_with_hyphen
-    e = assert_raises(ArgumentError) { @view.render(:partial => "test/a-in") }
-    assert_equal "The partial name (test/a-in) is not a valid Ruby identifier; " +
-      "make sure your partial name starts with underscore, " +
-      "and is followed by any combination of letters, numbers and underscores.", e.message
+    assert_nothing_raised { @view.render(:partial => "test/a-in") }
   end
 
   def test_render_partial_with_invalid_option_as
@@ -282,6 +280,14 @@ module RenderTestCases
     assert_nil @view.render(:partial => "test/customer", :collection => nil)
   end
 
+  def test_render_partial_without_object_does_not_put_partial_name_to_local_assigns
+    assert_equal 'false', @view.render(partial: 'test/partial_name_in_local_assigns')
+  end
+
+  def test_render_partial_with_nil_object_puts_partial_name_to_local_assigns
+    assert_equal 'true', @view.render(partial: 'test/partial_name_in_local_assigns', object: nil)
+  end
+
   def test_render_partial_with_nil_values_in_collection
     assert_equal "Hello: davidHello: Anonymous", @view.render(:partial => "test/customer", :collection => [ Customer.new("david"), nil ])
   end
@@ -603,3 +609,57 @@ class LazyViewRenderTest < ActiveSupport::TestCase
     silence_warnings { Encoding.default_external = old }
   end
 end
+
+class CachedCollectionViewRenderTest < CachedViewRenderTest
+  class CachedCustomer < Customer; end
+
+  teardown do
+    ActionView::PartialRenderer.collection_cache.clear
+  end
+
+  test "with custom key" do
+    customer = Customer.new("david")
+    key = cache_key([customer, 'key'], "test/_customer")
+
+    ActionView::PartialRenderer.collection_cache.write(key, 'Hello')
+
+    assert_equal "Hello",
+      @view.render(partial: "test/customer", collection: [customer], cache: ->(item) { [item, 'key'] })
+  end
+
+  test "with caching with custom key and rendering with different key" do
+    customer = Customer.new("david")
+    key = cache_key([customer, 'key'], "test/_customer")
+
+    ActionView::PartialRenderer.collection_cache.write(key, 'Hello')
+
+    assert_equal "Hello: david",
+      @view.render(partial: "test/customer", collection: [customer], cache: ->(item) { [item, 'another_key'] })
+  end
+
+  test "automatic caching with inferred cache name" do
+    customer = CachedCustomer.new("david")
+    key = cache_key(customer, "test/_cached_customer")
+
+    ActionView::PartialRenderer.collection_cache.write(key, 'Cached')
+
+    assert_equal "Cached",
+      @view.render(partial: "test/cached_customer", collection: [customer])
+  end
+
+  test "automatic caching with as name" do
+    customer = CachedCustomer.new("david")
+    key = cache_key(customer, "test/_cached_customer_as")
+
+    ActionView::PartialRenderer.collection_cache.write(key, 'Cached')
+
+    assert_equal "Cached",
+      @view.render(partial: "test/cached_customer_as", collection: [customer], as: :buyer)
+  end
+
+  private
+    def cache_key(names, virtual_path)
+      digest = ActionView::Digestor.digest name: virtual_path, finder: @view.lookup_context, dependencies: []
+      @view.fragment_cache_key([ *Array(names), digest ])
+    end
+end
diff --git a/actionview/test/template/sanitize_helper_test.rb b/actionview/test/template/sanitize_helper_test.rb
index e4be21be2c..efe846a7eb 100644
--- a/actionview/test/template/sanitize_helper_test.rb
+++ b/actionview/test/template/sanitize_helper_test.rb
@@ -29,6 +29,10 @@ class SanitizeHelperTest < ActionView::TestCase
     assert_equal "", strip_tags("<script>")
   end
 
+  def test_strip_tags_will_not_encode_special_characters
+    assert_equal "test\r\n\r\ntest", strip_tags("test\r\n\r\ntest")
+  end
+
   def test_sanitize_is_marked_safe
     assert sanitize("<html><script></script></html>").html_safe?
   end
diff --git a/actionview/test/template/streaming_render_test.rb b/actionview/test/template/streaming_render_test.rb
index 8a24d78e74..d06ba4ceb0 100644
--- a/actionview/test/template/streaming_render_test.rb
+++ b/actionview/test/template/streaming_render_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 class TestController < ActionController::Base
@@ -105,4 +104,8 @@ class FiberedTest < ActiveSupport::TestCase
       buffered_render(:template => "test/nested_streaming", :layout => "layouts/streaming")
   end
 
+  def test_render_with_streaming_and_capture
+    assert_equal "Yes, \n this works\n like a charm.",
+      buffered_render(template: "test/streaming", layout: "layouts/streaming_with_capture")
+  end
 end
diff --git a/actionview/test/template/template_test.rb b/actionview/test/template/template_test.rb
index c94508d678..921011b073 100644
--- a/actionview/test/template/template_test.rb
+++ b/actionview/test/template/template_test.rb
@@ -118,15 +118,17 @@ class TestERBTemplate < ActiveSupport::TestCase
   def test_refresh_with_templates
     @template = new_template("Hello", :virtual_path => "test/foo/bar")
     @template.locals = [:key]
-    @context.lookup_context.expects(:find_template).with("bar", %w(test/foo), false, [:key]).returns("template")
-    assert_equal "template", @template.refresh(@context)
+    assert_called_with(@context.lookup_context, :find_template,["bar", %w(test/foo), false, [:key]], returns: "template") do
+      assert_equal "template", @template.refresh(@context)
+    end
   end
 
   def test_refresh_with_partials
     @template = new_template("Hello", :virtual_path => "test/_foo")
     @template.locals = [:key]
-    @context.lookup_context.expects(:find_template).with("foo", %w(test), true, [:key]).returns("partial")
-    assert_equal "partial", @template.refresh(@context)
+    assert_called_with(@context.lookup_context, :find_template,[ "foo", %w(test), true, [:key]], returns: "partial") do
+      assert_equal "partial", @template.refresh(@context)
+    end
   end
 
   def test_refresh_raises_an_error_without_virtual_path
@@ -183,10 +185,43 @@ class TestERBTemplate < ActiveSupport::TestCase
   end
 
   def test_error_when_template_isnt_valid_utf8
-    assert_raises(ActionView::Template::Error, /\xFC/) do
+    e = assert_raises ActionView::Template::Error do
       @template = new_template("hello \xFCmlat", :virtual_path => nil)
       render
     end
+    assert_match(/\xFC/, e.message)
+  end
+
+  def test_not_eligible_for_collection_caching_without_cache_call
+    [
+      "<%= 'Hello' %>",
+      "<% cache_customer = 42 %>",
+      "<% cache customer.name do %><% end %>",
+      "<% my_cache customer do %><% end %>"
+    ].each do |body|
+      template = new_template(body, virtual_path: "test/foo/_customer")
+      assert_not template.eligible_for_collection_caching?, "Template #{body.inspect} should not be eligible for collection caching"
+    end
+  end
+
+  def test_eligible_for_collection_caching_with_cache_call_or_explicit
+    [
+      "<% cache customer do %><% end %>",
+      "<% cache(customer) do %><% end %>",
+      "<% cache( customer) do %><% end %>",
+      "<% cache( customer ) do %><% end %>",
+      "<%cache customer do %><% end %>",
+      "<%   cache   customer    do %><% end %>",
+      "  <% cache customer do %>\n<% end %>\n",
+      "<%# comment %><% cache customer do %><% end %>",
+      "<%# comment %>\n<% cache customer do %><% end %>",
+      "<%# comment\n line 2\n line 3 %>\n<% cache customer do %><% end %>",
+      "<%# comment 1 %>\n<%# comment 2 %>\n<% cache customer do %><% end %>",
+      "<%# comment 1 %>\n<%# Template Collection: customer %>\n<% my_cache customer do %><% end %>"
+    ].each do |body|
+      template = new_template(body, virtual_path: "test/foo/_customer")
+      assert template.eligible_for_collection_caching?, "Template #{body.inspect} should be eligible for collection caching"
+    end
   end
 
   def with_external_encoding(encoding)
diff --git a/actionview/test/template/test_case_test.rb b/actionview/test/template/test_case_test.rb
index 5ad1938b61..b057d43ee0 100644
--- a/actionview/test/template/test_case_test.rb
+++ b/actionview/test/template/test_case_test.rb
@@ -20,6 +20,7 @@ module ActionView
 
   class TestCase
     helper ASharedTestHelper
+    DeveloperStruct = Struct.new(:name)
 
     module SharedTests
       def self.included(test_case)
@@ -50,7 +51,7 @@ module ActionView
     end
 
     test "works without testing a helper module" do
-      assert_equal 'Eloy', render('developers/developer', :developer => stub(:name => 'Eloy'))
+      assert_equal 'Eloy', render('developers/developer', :developer => DeveloperStruct.new('Eloy'))
     end
 
     test "can render a layout with block" do
@@ -69,13 +70,15 @@ module ActionView
     end
 
     test "delegates notice to request.flash[:notice]" do
-      view.request.flash.expects(:[]).with(:notice)
-      view.notice
+      assert_called_with(view.request.flash, :[], [:notice]) do
+        view.notice
+      end
     end
 
     test "delegates alert to request.flash[:alert]" do
-      view.request.flash.expects(:[]).with(:alert)
-      view.alert
+      assert_called_with(view.request.flash, :[], [:alert]) do
+        view.alert
+      end
     end
 
     test "uses controller lookup context" do
@@ -119,7 +122,7 @@ module ActionView
     test "helper class that is being tested is always included in view instance" do
       @controller.controller_path = 'test'
 
-      @customers = [stub(:name => 'Eloy'), stub(:name => 'Manfred')]
+      @customers = [DeveloperStruct.new('Eloy'), DeveloperStruct.new('Manfred')]
       assert_match(/Hello: EloyHello: Manfred/, render(:partial => 'test/from_helper'))
     end
   end
@@ -209,7 +212,7 @@ module ActionView
     end
 
     test "is able to use routes" do
-      controller.request.assign_parameters(@routes, 'foo', 'index')
+      controller.request.assign_parameters(@routes, 'foo', 'index', {}, '/foo', [])
       assert_equal '/foo', url_for
       assert_equal '/bar', url_for(:controller => 'bar')
     end
@@ -255,15 +258,15 @@ module ActionView
     end
 
     test "is able to render partials with local variables" do
-      assert_equal 'Eloy', render('developers/developer', :developer => stub(:name => 'Eloy'))
+      assert_equal 'Eloy', render('developers/developer', :developer => DeveloperStruct.new('Eloy'))
       assert_equal 'Eloy', render(:partial => 'developers/developer',
-                                  :locals => { :developer => stub(:name => 'Eloy') })
+                                  :locals => { :developer => DeveloperStruct.new('Eloy') })
     end
 
     test "is able to render partials from templates and also use instance variables" do
       @controller.controller_path = "test"
 
-      @customers = [stub(:name => 'Eloy'), stub(:name => 'Manfred')]
+      @customers = [DeveloperStruct.new('Eloy'), DeveloperStruct.new('Manfred')]
       assert_match(/Hello: EloyHello: Manfred/, render(:file => 'test/list'))
     end
 
@@ -272,7 +275,7 @@ module ActionView
 
       view
 
-      @customers = [stub(:name => 'Eloy'), stub(:name => 'Manfred')]
+      @customers = [DeveloperStruct.new('Eloy'), DeveloperStruct.new('Manfred')]
       assert_match(/Hello: EloyHello: Manfred/, render(:file => 'test/list'))
     end
 
@@ -306,63 +309,6 @@ module ActionView
     end
   end
 
-  class RenderTemplateTest < ActionView::TestCase
-    test "supports specifying templates with a Regexp" do
-      controller.controller_path = "fun"
-      render(:template => "fun/games/hello_world")
-      assert_template %r{\Afun/games/hello_world\Z}
-    end
-
-    test "supports specifying partials" do
-      controller.controller_path = "test"
-      render(:template => "test/calling_partial_with_layout")
-      assert_template :partial => "_partial_for_use_in_layout"
-    end
-
-    test "supports specifying locals (passing)" do
-      controller.controller_path = "test"
-      render(:template => "test/calling_partial_with_layout")
-      assert_template :partial => "_partial_for_use_in_layout", :locals => { :name => "David" }
-    end
-
-    test "supports specifying locals (failing)" do
-      controller.controller_path = "test"
-      render(:template => "test/calling_partial_with_layout")
-      assert_raise ActiveSupport::TestCase::Assertion, /Somebody else.*David/m do
-        assert_template :partial => "_partial_for_use_in_layout", :locals => { :name => "Somebody Else" }
-      end
-    end
-
-    test 'supports different locals on the same partial' do
-      controller.controller_path = "test"
-      render(:template => "test/render_two_partials")
-      assert_template partial: '_partial', locals: { 'first' => '1' }
-      assert_template partial: '_partial', locals: { 'second' => '2' }
-    end
-
-    test 'raises descriptive error message when template was not rendered' do
-      controller.controller_path = "test"
-      render(template: "test/hello_world_with_partial")
-      e = assert_raise ActiveSupport::TestCase::Assertion do
-        assert_template partial: 'i_was_never_rendered', locals: { 'did_not' => 'happen' }
-      end
-      assert_match "i_was_never_rendered to be rendered but it was not.", e.message
-      assert_match 'Expected ["/test/partial"] to include "i_was_never_rendered"', e.message
-    end
-
-    test 'specifying locals works when the partial is inside a directory with underline prefix' do
-      controller.controller_path = "test"
-      render(template: 'test/render_partial_inside_directory')
-      assert_template partial: 'test/_directory/_partial_with_locales', locals: { 'name' => 'Jane' }
-    end
-
-    test 'specifying locals works when the partial is inside a directory without underline prefix' do
-      controller.controller_path = "test"
-      render(template: 'test/render_partial_inside_directory')
-      assert_template partial: 'test/_directory/partial_with_locales', locals: { 'name' => 'Jane' }
-    end
-  end
-
   module AHelperWithInitialize
     def initialize(*)
       super
diff --git a/actionview/test/template/text_helper_test.rb b/actionview/test/template/text_helper_test.rb
index f05b845e46..fae1965ffa 100644
--- a/actionview/test/template/text_helper_test.rb
+++ b/actionview/test/template/text_helper_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 class TextHelperTest < ActionView::TestCase
@@ -367,6 +366,10 @@ class TextHelperTest < ActionView::TestCase
     assert_equal options, passed_options
   end
 
+  def test_word_wrap_with_custom_break_sequence
+    assert_equal("1234567890\r\n1234567890\r\n1234567890", word_wrap("1234567890 " * 3, line_width: 2, break_sequence: "\r\n"))
+  end
+
   def test_pluralization
     assert_equal("1 count", pluralize(1, "count"))
     assert_equal("2 counts", pluralize(2, "count"))
@@ -384,6 +387,18 @@ class TextHelperTest < ActionView::TestCase
     assert_equal("12 berries", pluralize(12, "berry"))
   end
 
+  def test_pluralization_with_locale
+    ActiveSupport::Inflector.inflections(:de) do |inflect|
+      inflect.plural(/(person)$/i, '\1en')
+      inflect.singular(/(person)en$/i, '\1')
+    end
+
+    assert_equal("2 People", pluralize(2, "Person", locale: :en))
+    assert_equal("2 Personen", pluralize(2, "Person", locale: :de))
+
+    ActiveSupport::Inflector.inflections(:de).clear
+  end
+
   def test_cycle_class
     value = Cycle.new("one", 2, "3")
     assert_equal("one", value.to_s)
diff --git a/actionview/test/template/translation_helper_test.rb b/actionview/test/template/translation_helper_test.rb
index 8fde478ac9..261576bead 100644
--- a/actionview/test/template/translation_helper_test.rb
+++ b/actionview/test/template/translation_helper_test.rb
@@ -41,15 +41,17 @@ class TranslationHelperTest < ActiveSupport::TestCase
     I18n.backend.reload!
   end
 
-  def test_delegates_to_i18n_setting_the_rescue_format_option_to_html
-    I18n.expects(:translate).with(:foo, :locale => 'en', :raise=>true).returns("")
-    translate :foo, :locale => 'en'
+  def test_delegates_setting_to_i18n
+    assert_called_with(I18n, :translate, [:foo, :locale => 'en', :raise => true], returns: "") do
+      translate :foo, :locale => 'en'
+    end
   end
 
   def test_delegates_localize_to_i18n
     @time = Time.utc(2008, 7, 8, 12, 18, 38)
-    I18n.expects(:localize).with(@time)
-    localize @time
+    assert_called_with(I18n, :localize, [@time]) do
+      localize @time
+    end
   end
 
   def test_returns_missing_translation_message_wrapped_into_span
@@ -58,10 +60,10 @@ class TranslationHelperTest < ActiveSupport::TestCase
     assert_equal true, translate(:"translations.missing").html_safe?
   end
 
-  def test_returns_missing_translation_message_using_nil_as_rescue_format
-    expected = 'translation missing: en.translations.missing'
-    assert_equal expected, translate(:"translations.missing", :rescue_format => nil)
-    assert_equal false, translate(:"translations.missing", :rescue_format => nil).html_safe?
+  def test_returns_missing_translation_message_with_unescaped_interpolation
+    expected = '<span class="translation_missing" title="translation missing: en.translations.missing, name: Kir, year: 2015, vulnerable: &amp;quot; onclick=&amp;quot;alert()&amp;quot;">Missing</span>'
+    assert_equal expected, translate(:"translations.missing", name: "Kir", year: "2015", vulnerable: %{" onclick="alert()"})
+    assert translate(:"translations.missing").html_safe?
   end
 
   def test_raises_missing_translation_message_with_raise_config_option
@@ -96,12 +98,6 @@ class TranslationHelperTest < ActiveSupport::TestCase
     I18n.exception_handler = old_exception_handler
   end
 
-  def test_i18n_translate_defaults_to_nil_rescue_format
-    expected = 'translation missing: en.translations.missing'
-    assert_equal expected, I18n.translate(:"translations.missing")
-    assert_equal false, I18n.translate(:"translations.missing").html_safe?
-  end
-
   def test_translation_returning_an_array
     expected = %w(foo bar)
     assert_equal expected, translate(:"translations.array")
@@ -137,8 +133,9 @@ class TranslationHelperTest < ActiveSupport::TestCase
   end
 
   def test_translate_escapes_interpolations_in_translations_with_a_html_suffix
+    word_struct = Struct.new(:to_s)
     assert_equal '<a>Hello &lt;World&gt;</a>', translate(:'translations.interpolated_html', :word => '<World>')
-    assert_equal '<a>Hello &lt;World&gt;</a>', translate(:'translations.interpolated_html', :word => stub(:to_s => "<World>"))
+    assert_equal '<a>Hello &lt;World&gt;</a>', translate(:'translations.interpolated_html', :word => word_struct.new("<World>"))
   end
 
   def test_translate_with_html_count
@@ -157,6 +154,19 @@ class TranslationHelperTest < ActiveSupport::TestCase
     assert_equal true, translation.html_safe?
   end
 
+  def test_translate_with_missing_default
+    translation = translate(:'translations.missing', :default => :'translations.missing_html')
+    expected = '<span class="translation_missing" title="translation missing: en.translations.missing_html">Missing Html</span>'
+    assert_equal expected, translation
+    assert_equal true, translation.html_safe?
+  end
+
+  def test_translate_with_missing_default_and_raise_option
+    assert_raise(I18n::MissingTranslationData) do
+      translate(:'translations.missing', :default => :'translations.missing_html', :raise => true)
+    end
+  end
+
   def test_translate_with_two_defaults_named_html
     translation = translate(:'translations.missing', :default => [:'translations.missing_html', :'translations.hello_html'])
     assert_equal '<a>Hello World</a>', translation
@@ -180,11 +190,26 @@ class TranslationHelperTest < ActiveSupport::TestCase
     assert_equal 'A Generic String', translation
   end
 
+  def test_translate_with_object_default
+    translation = translate(:'translations.missing', default: 123)
+    assert_equal 123, translation
+  end
+
   def test_translate_with_array_of_string_defaults
     translation = translate(:'translations.missing', default: ['A Generic String', 'Second generic string'])
     assert_equal 'A Generic String', translation
   end
 
+  def test_translate_with_array_of_defaults_with_nil
+    translation = translate(:'translations.missing', default: [:'also_missing', nil, 'A Generic String'])
+    assert_equal 'A Generic String', translation
+  end
+
+  def test_translate_with_array_of_array_default
+    translation = translate(:'translations.missing', default: [[]])
+    assert_equal [], translation
+  end
+
   def test_translate_does_not_change_options
     options = {}
     translate(:'translations.missing', options)
diff --git a/actionview/test/template/url_helper_test.rb b/actionview/test/template/url_helper_test.rb
index 0d6f31af9b..50b7865f88 100644
--- a/actionview/test/template/url_helper_test.rb
+++ b/actionview/test/template/url_helper_test.rb
@@ -1,6 +1,4 @@
-# encoding: utf-8
 require 'abstract_unit'
-require 'minitest/mock'
 
 class UrlHelperTest < ActiveSupport::TestCase
 
@@ -380,6 +378,11 @@ class UrlHelperTest < ActiveSupport::TestCase
     assert_dom_equal %{<a href="/">Listing</a>}, link_to_if(true, "Listing", url_hash)
   end
 
+  def test_link_to_if_with_block
+    assert_equal "Fallback", link_to_if(false, "Showing", url_hash) { "Fallback" }
+    assert_dom_equal %{<a href="/">Listing</a>}, link_to_if(true, "Listing", url_hash) { "Fallback" }
+  end
+
   def request_for_url(url, opts = {})
     env = Rack::MockRequest.env_for("http://www.example.com#{url}", opts)
     ActionDispatch::Request.new(env)
@@ -480,6 +483,11 @@ class UrlHelperTest < ActiveSupport::TestCase
       link_to_unless_current("Listing", "http://www.example.com/")
   end
 
+  def test_link_to_unless_with_block
+    assert_dom_equal %{<a href="/">Showing</a>}, link_to_unless(false, "Showing", url_hash) { "Fallback" }
+    assert_equal "Fallback", link_to_unless(true, "Listing", url_hash) { "Fallback" }
+  end
+
   def test_mail_to
     assert_dom_equal %{<a href="mailto:david@loudthinking.com">david@loudthinking.com</a>}, mail_to("david@loudthinking.com")
     assert_dom_equal %{<a href="mailto:david@loudthinking.com">David Heinemeier Hansson</a>}, mail_to("david@loudthinking.com", "David Heinemeier Hansson")
@@ -491,11 +499,23 @@ class UrlHelperTest < ActiveSupport::TestCase
                  mail_to("david@loudthinking.com", "David Heinemeier Hansson", class: "admin")
   end
 
+  def test_mail_to_with_special_characters
+    assert_dom_equal(
+      %{<a href="mailto:%23%21%24%25%26%27%2A%2B-%2F%3D%3F%5E_%60%7B%7D%7C%7E@example.org">#!$%&amp;&#39;*+-/=?^_`{}|~@example.org</a>},
+      mail_to("#!$%&'*+-/=?^_`{}|~@example.org")
+    )
+  end
+
   def test_mail_with_options
     assert_dom_equal(
       %{<a href="mailto:me@example.com?cc=ccaddress%40example.com&amp;bcc=bccaddress%40example.com&amp;body=This%20is%20the%20body%20of%20the%20message.&amp;subject=This%20is%20an%20example%20email&amp;reply-to=foo%40bar.com">My email</a>},
       mail_to("me@example.com", "My email", cc: "ccaddress@example.com", bcc: "bccaddress@example.com", subject: "This is an example email", body: "This is the body of the message.", reply_to: "foo@bar.com")
     )
+
+    assert_dom_equal(
+      %{<a href="mailto:me@example.com?body=This%20is%20the%20body%20of%20the%20message.&amp;subject=This%20is%20an%20example%20email">My email</a>},
+      mail_to("me@example.com", "My email", cc: '', bcc: '', subject: "This is an example email", body: "This is the body of the message.")
+    )
   end
 
   def test_mail_to_with_img
@@ -624,13 +644,13 @@ class UrlHelperControllerTest < ActionController::TestCase
   end
 
   def test_named_route_url_shows_host_and_path
-    get :show_named_route, kind: 'url'
+    get :show_named_route, params: { kind: 'url' }
     assert_equal 'http://test.host/url_helper_controller_test/url_helper/show_named_route',
       @response.body
   end
 
   def test_named_route_path_shows_only_path
-    get :show_named_route, kind: 'path'
+    get :show_named_route, params: { kind: 'path' }
     assert_equal '/url_helper_controller_test/url_helper/show_named_route', @response.body
   end
 
@@ -646,7 +666,7 @@ class UrlHelperControllerTest < ActionController::TestCase
       end
     end
 
-    get :show_named_route, kind: 'url'
+    get :show_named_route, params: { kind: 'url' }
     assert_equal 'http://testtwo.host/url_helper_controller_test/url_helper/show_named_route', @response.body
   end
 
@@ -661,11 +681,11 @@ class UrlHelperControllerTest < ActionController::TestCase
   end
 
   def test_recall_params_should_normalize_id
-    get :show, id: '123'
+    get :show, params: { id: '123' }
     assert_equal 302, @response.status
     assert_equal 'http://test.host/url_helper_controller_test/url_helper/profile/123', @response.location
 
-    get :show, name: '123'
+    get :show, params: { name: '123' }
     assert_equal 'ok', @response.body
   end
 
@@ -704,7 +724,7 @@ class LinkToUnlessCurrentWithControllerTest < ActionController::TestCase
   end
 
   def test_link_to_unless_current_shows_link
-    get :show, id: 1
+    get :show, params: { id: 1 }
     assert_equal %{<a href="/tasks">tasks</a>\n} +
       %{<a href="#{@request.protocol}#{@request.host_with_port}/tasks">tasks</a>},
       @response.body
@@ -765,6 +785,13 @@ class SessionsController < ActionController::Base
     @session = Session.new(params[:id])
     render inline: "<%= url_for([@workshop, @session]) %>\n<%= link_to('Session', [@workshop, @session]) %>"
   end
+
+  def edit
+    @workshop = Workshop.new(params[:workshop_id])
+    @session = Session.new(params[:id])
+    @url = [@workshop, @session, format: params[:format]]
+    render inline: "<%= url_for(@url) %>\n<%= link_to('Session', @url) %>"
+  end
 end
 
 class PolymorphicControllerTest < ActionController::TestCase
@@ -778,21 +805,28 @@ class PolymorphicControllerTest < ActionController::TestCase
   def test_existing_resource
     @controller = WorkshopsController.new
 
-    get :show, id: 1
+    get :show, params: { id: 1 }
     assert_equal %{/workshops/1\n<a href="/workshops/1">Workshop</a>}, @response.body
   end
 
   def test_new_nested_resource
     @controller = SessionsController.new
 
-    get :index, workshop_id: 1
+    get :index, params: { workshop_id: 1 }
     assert_equal %{/workshops/1/sessions\n<a href="/workshops/1/sessions">Session</a>}, @response.body
   end
 
   def test_existing_nested_resource
     @controller = SessionsController.new
 
-    get :show, workshop_id: 1, id: 1
+    get :show, params: { workshop_id: 1, id: 1 }
     assert_equal %{/workshops/1/sessions/1\n<a href="/workshops/1/sessions/1">Session</a>}, @response.body
   end
+
+  def test_existing_nested_resource_with_params
+    @controller = SessionsController.new
+
+    get :edit, params: { workshop_id: 1, id: 1, format: "json"  }
+    assert_equal %{/workshops/1/sessions/1.json\n<a href="/workshops/1/sessions/1.json">Session</a>}, @response.body
+  end
 end
diff --git a/activejob/CHANGELOG.md b/activejob/CHANGELOG.md
index 794d05d1b4..79235019fe 100644
--- a/activejob/CHANGELOG.md
+++ b/activejob/CHANGELOG.md
@@ -1,3 +1,94 @@
+*   Fixed serializing `:at` option for `assert_enqueued_with`
+    and `assert_performed_with`.
+
+    *Wojciech Wnętrzak*
+
+*   Support passing array to `assert_enqueued_jobs` in `:only` option.
+
+    *Wojciech Wnętrzak*
+
+*   Add job priorities to Active Job.
+
+    *wvengen*
+
+*   Implement a simple `AsyncJob` processor and associated `AsyncAdapter` that
+    queue jobs to a `concurrent-ruby` thread pool.
+
+    *Jerry D'Antonio*
+
+*   Implement `provider_job_id` for `queue_classic` adapter. This requires the
+    latest, currently unreleased, version of queue_classic.
+
+    *Yves Senn*
+
+*   `assert_enqueued_with` and `assert_performed_with` now returns the matched
+    job instance for further assertions.
+
+    *Jean Boussier*
+
+*   Include I18n.locale into job serialization/deserialization and use it around
+    `perform`.
+
+    Fixes #20799.
+
+    *Johannes Opper*
+
+*   Allow `DelayedJob`, `Sidekiq`, `qu`, and `que` to report the job id back to
+    `ActiveJob::Base` as `provider_job_id`.
+
+    Fixes #18821.
+
+    *Kevin Deisz*, *Jeroen van Baarsen*
+
+*   `assert_enqueued_jobs` and `assert_performed_jobs` in block form use the
+    given number as expected value. This makes the error message much easier to
+    understand.
+
+    *y-yagi*
+
+*   A generated job now inherits from `app/jobs/application_job.rb` by default.
+
+    *Jeroen van Baarsen*
+
+*   Add an `:only` option to `perform_enqueued_jobs` to filter jobs based on
+    type.
+
+    This allows specific jobs to be tested, while preventing others from
+    being performed unnecessarily.
+
+    Example:
+
+        def test_hello_job
+          assert_performed_jobs 1, only: HelloJob do
+            HelloJob.perform_later('jeremy')
+            LoggingJob.perform_later
+          end
+        end
+
+    An array may also be specified, to support testing multiple jobs.
+
+    Example:
+
+        def test_hello_and_logging_jobs
+          assert_nothing_raised do
+            assert_performed_jobs 2, only: [HelloJob, LoggingJob] do
+              HelloJob.perform_later('jeremy')
+              LoggingJob.perform_later('stewie')
+              RescueJob.perform_later('david')
+            end
+          end
+        end
+
+    Fixes #18802.
+
+    *Michael Ryan*
+
+*   Allow keyword arguments to be used with Active Job.
+
+    Fixes #18741.
+
+    *Sean Griffin*
+
 *   Add `:only` option to `assert_enqueued_jobs`, to check the number of times
     a specific kind of job is enqueued.
 
@@ -38,5 +129,4 @@
 
     *Isaac Seymour*
 
-
 Please check [4-2-stable](https://github.com/rails/rails/blob/4-2-stable/activejob/CHANGELOG.md) for previous changes.
diff --git a/activejob/README.md b/activejob/README.md
index 8c83d3669a..f9a3183b1a 100644
--- a/activejob/README.md
+++ b/activejob/README.md
@@ -7,7 +7,7 @@ small units of work and run in parallel, really.
 
 It also serves as the backend for Action Mailer's #deliver_later functionality
 that makes it easy to turn any mailing into a job for running later. That's
-one of the most common jobs in a modern web application: Sending emails outside
+one of the most common jobs in a modern web application: sending emails outside
 of the request-response cycle, so the user doesn't have to wait on it.
 
 The main point is to ensure that all Rails apps will have a job infrastructure
@@ -102,7 +102,7 @@ see the API Documentation for [ActiveJob::QueueAdapters](http://api.rubyonrails.
 The latest version of Active Job can be installed with RubyGems:
 
 ```
-  % [sudo] gem install activejob
+  % gem install activejob
 ```
 
 Source code can be downloaded as part of the Rails project on GitHub
@@ -118,7 +118,7 @@ Active Job is released under the MIT license:
 
 ## Support
 
-API documentation is at
+API documentation is at:
 
 * http://api.rubyonrails.org
 
diff --git a/activejob/Rakefile b/activejob/Rakefile
index 1922f256ec..d9648a7f16 100644
--- a/activejob/Rakefile
+++ b/activejob/Rakefile
@@ -1,7 +1,6 @@
 require 'rake/testtask'
-require 'rubygems/package_task'
 
-ACTIVEJOB_ADAPTERS = %w(inline delayed_job qu que queue_classic resque sidekiq sneakers sucker_punch backburner test)
+ACTIVEJOB_ADAPTERS = %w(async inline delayed_job qu que queue_classic resque sidekiq sneakers sucker_punch backburner test)
 ACTIVEJOB_ADAPTERS -= %w(queue_classic) if defined?(JRUBY_VERSION)
 
 task default: :test
@@ -28,14 +27,14 @@ namespace :test do
   end
 
   ACTIVEJOB_ADAPTERS.each do |adapter|
-    task("env:#{adapter}") { ENV['AJADAPTER'] = adapter }
+    task("env:#{adapter}") { ENV['AJ_ADAPTER'] = adapter }
 
     Rake::TestTask.new(adapter => "test:env:#{adapter}") do |t|
       t.description = "Run adapter tests for #{adapter}"
       t.libs << 'test'
       t.test_files = FileList['test/cases/**/*_test.rb']
       t.verbose = true
-      t.warning = true
+      t.warning = false
       t.ruby_opts = ["--dev"] if defined?(JRUBY_VERSION)
     end
 
@@ -54,7 +53,7 @@ namespace :test do
         t.libs << 'test'
         t.test_files = FileList['test/integration/**/*_test.rb']
         t.verbose = true
-        t.warning = true
+        t.warning = false
         t.ruby_opts = ["--dev"] if defined?(JRUBY_VERSION)
       end
     end
@@ -74,17 +73,3 @@ def run_without_aborting(tasks)
 
   abort "Errors running #{errors.join(', ')}" if errors.any?
 end
-
-
-spec = eval(File.read('activejob.gemspec'))
-
-Gem::PackageTask.new(spec) do |p|
-  p.gem_spec = spec
-end
-
-desc 'Release to rubygems'
-task release: :package do
-  require 'rake/gemcutter'
-  Rake::Gemcutter::Tasks.new(spec).define
-  Rake::Task['gem:push'].invoke
-end
diff --git a/activejob/activejob.gemspec b/activejob/activejob.gemspec
index 5404ece804..24e38e495f 100644
--- a/activejob/activejob.gemspec
+++ b/activejob/activejob.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'Job framework with pluggable queues.'
   s.description = 'Declare job classes that can be run by a variety of queueing backends.'
 
-  s.required_ruby_version = '>= 2.2.0'
+  s.required_ruby_version = '>= 2.2.2'
 
   s.license = 'MIT'
 
diff --git a/activejob/lib/active_job.rb b/activejob/lib/active_job.rb
index 3d4f63b261..eb8091a805 100644
--- a/activejob/lib/active_job.rb
+++ b/activejob/lib/active_job.rb
@@ -32,6 +32,7 @@ module ActiveJob
   autoload :Base
   autoload :QueueAdapters
   autoload :ConfiguredJob
+  autoload :AsyncJob
   autoload :TestCase
   autoload :TestHelper
 end
diff --git a/activejob/lib/active_job/arguments.rb b/activejob/lib/active_job/arguments.rb
index 752be6898e..8e462bfe5d 100644
--- a/activejob/lib/active_job/arguments.rb
+++ b/activejob/lib/active_job/arguments.rb
@@ -1,10 +1,12 @@
-require 'active_support/core_ext/hash/indifferent_access'
+require 'active_support/core_ext/hash'
 
 module ActiveJob
   # Raised when an exception is raised during job arguments deserialization.
   #
   # Wraps the original exception raised as +original_exception+.
   class DeserializationError < StandardError
+    # The original exception that was raised during deserialization of job
+    # arguments.
     attr_reader :original_exception
 
     def initialize(e) #:nodoc:
@@ -14,16 +16,17 @@ module ActiveJob
     end
   end
 
-  # Raised when an unsupported argument type is being set as job argument. We
+  # Raised when an unsupported argument type is set as a job argument. We
   # currently support NilClass, Fixnum, Float, String, TrueClass, FalseClass,
-  # Bignum and object that can be represented as GlobalIDs (ex: Active Record).
-  # Also raised if you set the key for a Hash something else than a string or
-  # a symbol.
-  class SerializationError < ArgumentError
-  end
+  # Bignum and objects that can be represented as GlobalIDs (ex: Active Record).
+  # Raised if you set the key for a Hash something else than a string or
+  # a symbol. Also raised when trying to serialize an object which can't be
+  # identified with a Global ID - such as an unpersisted Active Record model.
+  class SerializationError < ArgumentError; end
 
   module Arguments
     extend self
+    # :nodoc:
     TYPE_WHITELIST = [ NilClass, Fixnum, Float, String, TrueClass, FalseClass, Bignum ]
 
     # Serializes a set of arguments. Whitelisted types are returned
@@ -43,21 +46,31 @@ module ActiveJob
     end
 
     private
+      # :nodoc:
       GLOBALID_KEY = '_aj_globalid'.freeze
-      private_constant :GLOBALID_KEY
+      # :nodoc:
+      SYMBOL_KEYS_KEY = '_aj_symbol_keys'.freeze
+      # :nodoc:
+      WITH_INDIFFERENT_ACCESS_KEY = '_aj_hash_with_indifferent_access'.freeze
+      private_constant :GLOBALID_KEY, :SYMBOL_KEYS_KEY, :WITH_INDIFFERENT_ACCESS_KEY
 
       def serialize_argument(argument)
         case argument
         when *TYPE_WHITELIST
           argument
         when GlobalID::Identification
-          { GLOBALID_KEY => argument.to_global_id.to_s }
+          convert_to_global_id_hash(argument)
         when Array
           argument.map { |arg| serialize_argument(arg) }
+        when ActiveSupport::HashWithIndifferentAccess
+          result = serialize_hash(argument)
+          result[WITH_INDIFFERENT_ACCESS_KEY] = serialize_argument(true)
+          result
         when Hash
-          argument.each_with_object({}) do |(key, value), hash|
-            hash[serialize_hash_key(key)] = serialize_argument(value)
-          end
+          symbol_keys = argument.each_key.grep(Symbol).map(&:to_s)
+          result = serialize_hash(argument)
+          result[SYMBOL_KEYS_KEY] = symbol_keys
+          result
         else
           raise SerializationError.new("Unsupported argument type: #{argument.class.name}")
         end
@@ -75,7 +88,7 @@ module ActiveJob
           if serialized_global_id?(argument)
             deserialize_global_id argument
           else
-            deserialize_hash argument
+            deserialize_hash(argument)
           end
         else
           raise ArgumentError, "Can only deserialize primitive arguments: #{argument.inspect}"
@@ -90,13 +103,28 @@ module ActiveJob
         GlobalID::Locator.locate hash[GLOBALID_KEY]
       end
 
+      def serialize_hash(argument)
+        argument.each_with_object({}) do |(key, value), hash|
+          hash[serialize_hash_key(key)] = serialize_argument(value)
+        end
+      end
+
       def deserialize_hash(serialized_hash)
-        serialized_hash.each_with_object({}.with_indifferent_access) do |(key, value), hash|
-          hash[key] = deserialize_argument(value)
+        result = serialized_hash.transform_values { |v| deserialize_argument(v) }
+        if result.delete(WITH_INDIFFERENT_ACCESS_KEY)
+          result = result.with_indifferent_access
+        elsif symbol_keys = result.delete(SYMBOL_KEYS_KEY)
+          result = transform_symbol_keys(result, symbol_keys)
         end
+        result
       end
 
-      RESERVED_KEYS = [GLOBALID_KEY, GLOBALID_KEY.to_sym]
+      # :nodoc:
+      RESERVED_KEYS = [
+        GLOBALID_KEY, GLOBALID_KEY.to_sym,
+        SYMBOL_KEYS_KEY, SYMBOL_KEYS_KEY.to_sym,
+        WITH_INDIFFERENT_ACCESS_KEY, WITH_INDIFFERENT_ACCESS_KEY.to_sym,
+      ]
       private_constant :RESERVED_KEYS
 
       def serialize_hash_key(key)
@@ -109,5 +137,22 @@ module ActiveJob
           raise SerializationError.new("Only string and symbol hash keys may be serialized as job arguments, but #{key.inspect} is a #{key.class}")
         end
       end
+
+      def transform_symbol_keys(hash, symbol_keys)
+        hash.transform_keys do |key|
+          if symbol_keys.include?(key)
+            key.to_sym
+          else
+            key
+          end
+        end
+      end
+
+      def convert_to_global_id_hash(argument)
+        { GLOBALID_KEY => argument.to_global_id.to_s }
+      rescue URI::GID::MissingModelIdError
+        raise SerializationError, "Unable to serialize #{argument.class} " \
+          "without an id. (Maybe you forgot to call save?)"
+      end
   end
 end
diff --git a/activejob/lib/active_job/async_job.rb b/activejob/lib/active_job/async_job.rb
new file mode 100644
index 0000000000..6c1c070994
--- /dev/null
+++ b/activejob/lib/active_job/async_job.rb
@@ -0,0 +1,74 @@
+require 'concurrent'
+
+module ActiveJob
+  # == Active Job Async Job
+  #
+  # When enqueueing jobs with Async Job each job will be executed asynchronously
+  # on a +concurrent-ruby+ thread pool. All job data is retained in memory.
+  # Because job data is not saved to a persistent datastore there is no
+  # additional infrastructure needed and jobs process quickly. The lack of
+  # persistence, however, means that all unprocessed jobs will be lost on
+  # application restart. Therefore in-memory queue adapters are unsuitable for
+  # most production environments but are excellent for development and testing.
+  #
+  # Read more about Concurrent Ruby {here}[https://github.com/ruby-concurrency/concurrent-ruby].
+  #
+  # To use Async Job set the queue_adapter config to +:async+.
+  #
+  #   Rails.application.config.active_job.queue_adapter = :async
+  #
+  # Async Job supports job queues specified with +queue_as+. Queues are created
+  # automatically as needed and each has its own thread pool.
+  class AsyncJob
+
+    DEFAULT_EXECUTOR_OPTIONS = {
+      min_threads:     [2, Concurrent.processor_count].max,
+      max_threads:     Concurrent.processor_count * 10,
+      auto_terminate:  true,
+      idletime:        60, # 1 minute
+      max_queue:       0, # unlimited
+      fallback_policy: :caller_runs # shouldn't matter -- 0 max queue
+    }.freeze
+
+    QUEUES = Concurrent::Map.new do |hash, queue_name| #:nodoc:
+      hash.compute_if_absent(queue_name) { ActiveJob::AsyncJob.create_thread_pool }
+    end
+
+    class << self
+      # Forces jobs to process immediately when testing the Active Job gem.
+      # This should only be called from within unit tests.
+      def perform_immediately! #:nodoc:
+        @perform_immediately = true
+      end
+
+      # Allows jobs to run asynchronously when testing the Active Job gem.
+      # This should only be called from within unit tests.
+      def perform_asynchronously! #:nodoc:
+        @perform_immediately = false
+      end
+
+      def create_thread_pool #:nodoc:
+        if @perform_immediately
+          Concurrent::ImmediateExecutor.new
+        else
+          Concurrent::ThreadPoolExecutor.new(DEFAULT_EXECUTOR_OPTIONS)
+        end
+      end
+
+      def enqueue(job_data, queue: 'default') #:nodoc:
+        QUEUES[queue].post(job_data) { |job| ActiveJob::Base.execute(job) }
+      end
+
+      def enqueue_at(job_data, timestamp, queue: 'default') #:nodoc:
+        delay = timestamp - Time.current.to_f
+        if delay > 0
+          Concurrent::ScheduledTask.execute(delay, args: [job_data], executor: QUEUES[queue]) do |job|
+            ActiveJob::Base.execute(job)
+          end
+        else
+          enqueue(job_data, queue: queue)
+        end
+      end
+    end
+  end
+end
diff --git a/activejob/lib/active_job/base.rb b/activejob/lib/active_job/base.rb
index fd49b3fda5..e5f09f65fb 100644
--- a/activejob/lib/active_job/base.rb
+++ b/activejob/lib/active_job/base.rb
@@ -1,10 +1,12 @@
 require 'active_job/core'
 require 'active_job/queue_adapter'
 require 'active_job/queue_name'
+require 'active_job/queue_priority'
 require 'active_job/enqueuing'
 require 'active_job/execution'
 require 'active_job/callbacks'
 require 'active_job/logging'
+require 'active_job/translation'
 
 module ActiveJob #:nodoc:
   # = Active Job
@@ -56,10 +58,12 @@ module ActiveJob #:nodoc:
     include Core
     include QueueAdapter
     include QueueName
+    include QueuePriority
     include Enqueuing
     include Execution
     include Callbacks
     include Logging
+    include Translation
 
     ActiveSupport.run_load_hooks(:active_job, self)
   end
diff --git a/activejob/lib/active_job/core.rb b/activejob/lib/active_job/core.rb
index ddd7d1361c..19b900a285 100644
--- a/activejob/lib/active_job/core.rb
+++ b/activejob/lib/active_job/core.rb
@@ -1,4 +1,6 @@
 module ActiveJob
+  # Provides general behavior that will be included into every Active Job
+  # object that inherits from ActiveJob::Base.
   module Core
     extend ActiveSupport::Concern
 
@@ -15,6 +17,15 @@ module ActiveJob
 
       # Queue in which the job will reside.
       attr_writer :queue_name
+
+      # Priority that the job will have (lower is more priority).
+      attr_writer :priority
+
+      # ID optionally provided by adapter
+      attr_accessor :provider_job_id
+
+      # I18n.locale to be used during the job.
+      attr_accessor :locale
     end
 
     # These methods will be included into any Active Job object, adding
@@ -35,6 +46,7 @@ module ActiveJob
       # * <tt>:wait</tt> - Enqueues the job with the specified delay
       # * <tt>:wait_until</tt> - Enqueues the job at the time specified
       # * <tt>:queue</tt> - Enqueues the job on the specified queue
+      # * <tt>:priority</tt> - Enqueues the job with the specified priority
       #
       # ==== Examples
       #
@@ -43,6 +55,7 @@ module ActiveJob
       #    VideoJob.set(wait_until: Time.now.tomorrow).perform_later(Video.last)
       #    VideoJob.set(queue: :some_queue, wait: 5.minutes).perform_later(Video.last)
       #    VideoJob.set(queue: :some_queue, wait_until: Time.now.tomorrow).perform_later(Video.last)
+      #    VideoJob.set(queue: :some_queue, wait: 5.minutes, priority: 10).perform_later(Video.last)
       def set(options={})
         ConfiguredJob.new(self, options)
       end
@@ -54,6 +67,7 @@ module ActiveJob
       @arguments  = arguments
       @job_id     = SecureRandom.uuid
       @queue_name = self.class.queue_name
+      @priority   = self.class.priority
     end
 
     # Returns a hash with the job data that can safely be passed to the
@@ -63,7 +77,9 @@ module ActiveJob
         'job_class'  => self.class.name,
         'job_id'     => job_id,
         'queue_name' => queue_name,
-        'arguments'  => serialize_arguments(arguments)
+        'priority'   => priority,
+        'arguments'  => serialize_arguments(arguments),
+        'locale'     => I18n.locale
       }
     end
 
@@ -90,7 +106,9 @@ module ActiveJob
     def deserialize(job_data)
       self.job_id               = job_data['job_id']
       self.queue_name           = job_data['queue_name']
+      self.priority             = job_data['priority']
       self.serialized_arguments = job_data['arguments']
+      self.locale               = job_data['locale'] || I18n.locale
     end
 
     private
diff --git a/activejob/lib/active_job/enqueuing.rb b/activejob/lib/active_job/enqueuing.rb
index 430c17e1bf..22154457fd 100644
--- a/activejob/lib/active_job/enqueuing.rb
+++ b/activejob/lib/active_job/enqueuing.rb
@@ -1,6 +1,7 @@
 require 'active_job/arguments'
 
 module ActiveJob
+  # Provides behavior for enqueuing and retrying jobs.
   module Enqueuing
     extend ActiveSupport::Concern
 
@@ -31,6 +32,7 @@ module ActiveJob
     # * <tt>:wait</tt> - Enqueues the job with the specified delay
     # * <tt>:wait_until</tt> - Enqueues the job at the time specified
     # * <tt>:queue</tt> - Enqueues the job on the specified queue
+    # * <tt>:priority</tt> - Enqueues the job with the specified priority
     #
     # ==== Examples
     #
@@ -53,6 +55,7 @@ module ActiveJob
     # * <tt>:wait</tt> - Enqueues the job with the specified delay
     # * <tt>:wait_until</tt> - Enqueues the job at the time specified
     # * <tt>:queue</tt> - Enqueues the job on the specified queue
+    # * <tt>:priority</tt> - Enqueues the job with the specified priority
     #
     # ==== Examples
     #
@@ -60,10 +63,12 @@ module ActiveJob
     #    my_job_instance.enqueue wait: 5.minutes
     #    my_job_instance.enqueue queue: :important
     #    my_job_instance.enqueue wait_until: Date.tomorrow.midnight
+    #    my_job_instance.enqueue priority: 10
     def enqueue(options={})
       self.scheduled_at = options[:wait].seconds.from_now.to_f if options[:wait]
       self.scheduled_at = options[:wait_until].to_f if options[:wait_until]
       self.queue_name   = self.class.queue_name_from_part(options[:queue]) if options[:queue]
+      self.priority     = options[:priority].to_i if options[:priority]
       run_callbacks :enqueue do
         if self.scheduled_at
           self.class.queue_adapter.enqueue_at self, self.scheduled_at
diff --git a/activejob/lib/active_job/logging.rb b/activejob/lib/active_job/logging.rb
index cd29e6908e..605057d1e8 100644
--- a/activejob/lib/active_job/logging.rb
+++ b/activejob/lib/active_job/logging.rb
@@ -1,3 +1,4 @@
+require 'active_support/core_ext/hash/transform_values'
 require 'active_support/core_ext/string/filters'
 require 'active_support/tagged_logging'
 require 'active_support/logger'
@@ -25,7 +26,7 @@ module ActiveJob
         end
       end
 
-      before_enqueue do |job|
+      after_enqueue do |job|
         if job.scheduled_at
           ActiveSupport::Notifications.instrument "enqueue_at.active_job",
             adapter: job.class.queue_adapter, job: job
@@ -81,18 +82,31 @@ module ActiveJob
 
       private
         def queue_name(event)
-          event.payload[:adapter].name.demodulize.remove('Adapter') + "(#{event.payload[:job].queue_name})"
+          event.payload[:adapter].class.name.demodulize.remove('Adapter') + "(#{event.payload[:job].queue_name})"
         end
 
         def args_info(job)
           if job.arguments.any?
             ' with arguments: ' +
-              job.arguments.map { |arg| arg.try(:to_global_id).try(:to_s) || arg.inspect }.join(', ')
+              job.arguments.map { |arg| format(arg).inspect }.join(', ')
           else
             ''
           end
         end
 
+        def format(arg)
+          case arg
+          when Hash
+            arg.transform_values { |value| format(value) }
+          when Array
+            arg.map { |value| format(value) }
+          when GlobalID::Identification
+            arg.to_global_id rescue arg
+          else
+            arg
+          end
+        end
+
         def scheduled_at(event)
           Time.at(event.payload[:job].scheduled_at).utc
         end
diff --git a/activejob/lib/active_job/queue_adapter.rb b/activejob/lib/active_job/queue_adapter.rb
index d610d30e01..457015b741 100644
--- a/activejob/lib/active_job/queue_adapter.rb
+++ b/activejob/lib/active_job/queue_adapter.rb
@@ -1,35 +1,63 @@
 require 'active_job/queue_adapters/inline_adapter'
+require 'active_support/core_ext/class/attribute'
 require 'active_support/core_ext/string/inflections'
 
 module ActiveJob
   # The <tt>ActiveJob::QueueAdapter</tt> module is used to load the
-  # correct adapter. The default queue adapter is the :inline queue.
+  # correct adapter. The default queue adapter is the +:inline+ queue.
   module QueueAdapter #:nodoc:
     extend ActiveSupport::Concern
 
+    included do
+      class_attribute :_queue_adapter, instance_accessor: false, instance_predicate: false
+      self.queue_adapter = :inline
+    end
+
     # Includes the setter method for changing the active queue adapter.
     module ClassMethods
-      mattr_reader(:queue_adapter) { ActiveJob::QueueAdapters::InlineAdapter }
+      # Returns the backend queue provider. The default queue adapter
+      # is the +:inline+ queue. See QueueAdapters for more information.
+      def queue_adapter
+        _queue_adapter
+      end
 
       # Specify the backend queue provider. The default queue adapter
-      # is the :inline queue. See QueueAdapters for more
+      # is the +:inline+ queue. See QueueAdapters for more
       # information.
-      def queue_adapter=(name_or_adapter)
-        @@queue_adapter = \
-          case name_or_adapter
-          when :test
-            ActiveJob::QueueAdapters::TestAdapter.new
-          when Symbol, String
-            load_adapter(name_or_adapter)
-          else
-            name_or_adapter if name_or_adapter.respond_to?(:enqueue)
-          end
+      def queue_adapter=(name_or_adapter_or_class)
+        self._queue_adapter = interpret_adapter(name_or_adapter_or_class)
       end
 
       private
-        def load_adapter(name)
-          "ActiveJob::QueueAdapters::#{name.to_s.camelize}Adapter".constantize
+
+      def interpret_adapter(name_or_adapter_or_class)
+        case name_or_adapter_or_class
+        when Symbol, String
+          ActiveJob::QueueAdapters.lookup(name_or_adapter_or_class).new
+        else
+          if queue_adapter?(name_or_adapter_or_class)
+            name_or_adapter_or_class
+          elsif queue_adapter_class?(name_or_adapter_or_class)
+            ActiveSupport::Deprecation.warn "Passing an adapter class is deprecated " \
+              "and will be removed in Rails 5.1. Please pass an adapter name " \
+              "(.queue_adapter = :#{name_or_adapter_or_class.name.demodulize.remove('Adapter').underscore}) " \
+              "or an instance (.queue_adapter = #{name_or_adapter_or_class.name}.new) instead."
+              name_or_adapter_or_class.new
+          else
+            raise ArgumentError
+          end
         end
+      end
+
+      QUEUE_ADAPTER_METHODS = [:enqueue, :enqueue_at].freeze
+
+      def queue_adapter?(object)
+        QUEUE_ADAPTER_METHODS.all? { |meth| object.respond_to?(meth) }
+      end
+
+      def queue_adapter_class?(object)
+        object.is_a?(Class) && QUEUE_ADAPTER_METHODS.all? { |meth| object.public_method_defined?(meth) }
+      end
     end
   end
 end
diff --git a/activejob/lib/active_job/queue_adapters.rb b/activejob/lib/active_job/queue_adapters.rb
index 4b91c93dbe..aeb1fe1e73 100644
--- a/activejob/lib/active_job/queue_adapters.rb
+++ b/activejob/lib/active_job/queue_adapters.rb
@@ -12,31 +12,102 @@ module ActiveJob
   # * {Sidekiq}[http://sidekiq.org]
   # * {Sneakers}[https://github.com/jondot/sneakers]
   # * {Sucker Punch}[https://github.com/brandonhilkert/sucker_punch]
+  # * {Active Job Async Job}[http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters/AsyncAdapter.html]
+  # * {Active Job Inline}[http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters/InlineAdapter.html]
   #
   # === Backends Features
   #
-  #   |                   | Async | Queues | Delayed   | Priorities | Timeout | Retries |
-  #   |-------------------|-------|--------|-----------|------------|---------|---------|
-  #   | Backburner        | Yes   | Yes    | Yes       | Yes        | Job     | Global  |
-  #   | Delayed Job       | Yes   | Yes    | Yes       | Job        | Global  | Global  |
-  #   | Qu                | Yes   | Yes    | No        | No         | No      | Global  |
-  #   | Que               | Yes   | Yes    | Yes       | Job        | No      | Job     |
-  #   | queue_classic     | Yes   | Yes    | No*       | No         | No      | No      |
-  #   | Resque            | Yes   | Yes    | Yes (Gem) | Queue      | Global  | Yes     |
-  #   | Sidekiq           | Yes   | Yes    | Yes       | Queue      | No      | Job     |
-  #   | Sneakers          | Yes   | Yes    | No        | Queue      | Queue   | No      |
-  #   | Sucker Punch      | Yes   | Yes    | No        | No         | No      | No      |
-  #   | Active Job Inline | No    | Yes    | N/A       | N/A        | N/A     | N/A     |
-  #   | Active Job        | Yes   | Yes    | Yes       | No         | No      | No      |
+  #   |                   | Async | Queues | Delayed    | Priorities | Timeout | Retries |
+  #   |-------------------|-------|--------|------------|------------|---------|---------|
+  #   | Backburner        | Yes   | Yes    | Yes        | Yes        | Job     | Global  |
+  #   | Delayed Job       | Yes   | Yes    | Yes        | Job        | Global  | Global  |
+  #   | Qu                | Yes   | Yes    | No         | No         | No      | Global  |
+  #   | Que               | Yes   | Yes    | Yes        | Job        | No      | Job     |
+  #   | queue_classic     | Yes   | Yes    | Yes*       | No         | No      | No      |
+  #   | Resque            | Yes   | Yes    | Yes (Gem)  | Queue      | Global  | Yes     |
+  #   | Sidekiq           | Yes   | Yes    | Yes        | Queue      | No      | Job     |
+  #   | Sneakers          | Yes   | Yes    | No         | Queue      | Queue   | No      |
+  #   | Sucker Punch      | Yes   | Yes    | No         | No         | No      | No      |
+  #   | Active Job Async  | Yes   | Yes    | Yes        | No         | No      | No      |
+  #   | Active Job Inline | No    | Yes    | N/A        | N/A        | N/A     | N/A     |
+  #
+  # ==== Async
+  #
+  # Yes: The Queue Adapter runs the jobs in a separate or forked process.
+  #
+  # No: The job is run in the same process.
+  #
+  # ==== Queues
+  #
+  # Yes: Jobs may set which queue they are run in with queue_as or by using the set
+  # method.
+  #
+  # ==== Delayed
+  #
+  # Yes: The adapter will run the job in the future through perform_later.
+  #
+  # (Gem): An additional gem is required to use perform_later with this adapter.
+  #
+  # No: The adapter will run jobs at the next opportunity and cannot use perform_later.
+  #
+  # N/A: The adapter does not support queueing.
   #
   # NOTE:
-  # queue_classic does not support Job scheduling. However you can implement this
-  # yourself or you can use the queue_classic-later gem. See the documentation for
-  # ActiveJob::QueueAdapters::QueueClassicAdapter.
+  # queue_classic supports job scheduling since version 3.1.
+  # For older versions you can use the queue_classic-later gem.
+  #
+  # ==== Priorities
+  #
+  # The order in which jobs are processed can be configured differently depending
+  # on the adapter.
+  #
+  # Job: Any class inheriting from the adapter may set the priority on the job
+  # object relative to other jobs.
+  #
+  # Queue: The adapter can set the priority for job queues, when setting a queue
+  # with Active Job this will be respected.
+  #
+  # Yes: Allows the priority to be set on the job object, at the queue level or
+  # as default configuration option.
+  #
+  # No: Does not allow the priority of jobs to be configured.
   #
+  # N/A: The adapter does not support queueing, and therefore sorting them.
+  #
+  # ==== Timeout
+  #
+  # When a job will stop after the allotted time.
+  #
+  # Job: The timeout can be set for each instance of the job class.
+  #
+  # Queue: The timeout is set for all jobs on the queue.
+  #
+  # Global: The adapter is configured that all jobs have a maximum run time.
+  #
+  # N/A: This adapter does not run in a separate process, and therefore timeout
+  # is unsupported.
+  #
+  # ==== Retries
+  #
+  # Job: The number of retries can be set per instance of the job class.
+  #
+  # Yes: The Number of retries can be configured globally, for each instance or
+  # on the queue. This adapter may also present failed instances of the job class
+  # that can be restarted.
+  #
+  # Global: The adapter has a global number of retries.
+  #
+  # N/A: The adapter does not run in a separate process, and therefore doesn't
+  # support retries.
+  #
+  # === Async and Inline Queue Adapters
+  #
+  # Active Job has two built-in queue adapters intended for development and
+  # testing: +:async+ and +:inline+.
   module QueueAdapters
     extend ActiveSupport::Autoload
 
+    autoload :AsyncAdapter
     autoload :InlineAdapter
     autoload :BackburnerAdapter
     autoload :DelayedJobAdapter
@@ -48,5 +119,18 @@ module ActiveJob
     autoload :SneakersAdapter
     autoload :SuckerPunchAdapter
     autoload :TestAdapter
+
+    ADAPTER = 'Adapter'.freeze
+    private_constant :ADAPTER
+
+    class << self
+      # Returns adapter for specified name.
+      #
+      #   ActiveJob::QueueAdapters.lookup(:sidekiq)
+      #   # => ActiveJob::QueueAdapters::SidekiqAdapter
+      def lookup(name)
+        const_get(name.to_s.camelize << ADAPTER)
+      end
+    end
   end
 end
diff --git a/activejob/lib/active_job/queue_adapters/async_adapter.rb b/activejob/lib/active_job/queue_adapters/async_adapter.rb
new file mode 100644
index 0000000000..3fc27f56e7
--- /dev/null
+++ b/activejob/lib/active_job/queue_adapters/async_adapter.rb
@@ -0,0 +1,23 @@
+require 'active_job/async_job'
+
+module ActiveJob
+  module QueueAdapters
+    # == Active Job Async adapter
+    #
+    # When enqueueing jobs with the Async adapter the job will be executed
+    # asynchronously using {AsyncJob}[http://api.rubyonrails.org/classes/ActiveJob/AsyncJob.html].
+    #
+    # To use +AsyncJob+ set the queue_adapter config to +:async+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :async
+    class AsyncAdapter
+      def enqueue(job) #:nodoc:
+        ActiveJob::AsyncJob.enqueue(job.serialize, queue: job.queue_name)
+      end
+
+      def enqueue_at(job, timestamp) #:nodoc:
+        ActiveJob::AsyncJob.enqueue_at(job.serialize, timestamp, queue: job.queue_name)
+      end
+    end
+  end
+end
diff --git a/activejob/lib/active_job/queue_adapters/backburner_adapter.rb b/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
index 2453d065de..17703e3e41 100644
--- a/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
@@ -13,15 +13,13 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :backburner
     class BackburnerAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name
-        end
+      def enqueue(job) #:nodoc:
+        Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          delay = timestamp - Time.current.to_f
-          Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name, delay: delay
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        delay = timestamp - Time.current.to_f
+        Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name, delay: delay
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb b/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
index 69d9e70de3..0a785fad3b 100644
--- a/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
@@ -13,14 +13,16 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :delayed_job
     class DelayedJobAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          Delayed::Job.enqueue(JobWrapper.new(job.serialize), queue: job.queue_name)
-        end
+      def enqueue(job) #:nodoc:
+        delayed_job = Delayed::Job.enqueue(JobWrapper.new(job.serialize), queue: job.queue_name, priority: job.priority)
+        job.provider_job_id = delayed_job.id
+        delayed_job
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          Delayed::Job.enqueue(JobWrapper.new(job.serialize), queue: job.queue_name, run_at: Time.at(timestamp))
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        delayed_job = Delayed::Job.enqueue(JobWrapper.new(job.serialize), queue: job.queue_name, priority: job.priority, run_at: Time.at(timestamp))
+        job.provider_job_id = delayed_job.id
+        delayed_job
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/inline_adapter.rb b/activejob/lib/active_job/queue_adapters/inline_adapter.rb
index e25d88e723..8ad5f4de07 100644
--- a/activejob/lib/active_job/queue_adapters/inline_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/inline_adapter.rb
@@ -9,14 +9,12 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :inline
     class InlineAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          Base.execute(job.serialize)
-        end
+      def enqueue(job) #:nodoc:
+        Base.execute(job.serialize)
+      end
 
-        def enqueue_at(*) #:nodoc:
-          raise NotImplementedError.new("Use a queueing backend to enqueue jobs in the future. Read more at http://guides.rubyonrails.org/active_job_basics.html")
-        end
+      def enqueue_at(*) #:nodoc:
+        raise NotImplementedError, "Use a queueing backend to enqueue jobs in the future. Read more at http://guides.rubyonrails.org/active_job_basics.html"
       end
     end
   end
diff --git a/activejob/lib/active_job/queue_adapters/qu_adapter.rb b/activejob/lib/active_job/queue_adapters/qu_adapter.rb
index 30aa5a4670..0e198922fc 100644
--- a/activejob/lib/active_job/queue_adapters/qu_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/qu_adapter.rb
@@ -16,16 +16,18 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :qu
     class QuAdapter
-      class << self
-        def enqueue(job, *args) #:nodoc:
-          Qu::Payload.new(klass: JobWrapper, args: [job.serialize]).tap do |payload|
-            payload.instance_variable_set(:@queue, job.queue_name)
-          end.push
-        end
+      def enqueue(job, *args) #:nodoc:
+        qu_job = Qu::Payload.new(klass: JobWrapper, args: [job.serialize]).tap do |payload|
+          payload.instance_variable_set(:@queue, job.queue_name)
+        end.push
+        
+        # qu_job can be nil depending on the configured backend
+        job.provider_job_id = qu_job.id unless qu_job.nil?
+        qu_job
+      end
 
-        def enqueue_at(job, timestamp, *args) #:nodoc:
-          raise NotImplementedError
-        end
+      def enqueue_at(job, timestamp, *args) #:nodoc:
+        raise NotImplementedError, "This queueing backend does not support scheduling jobs. To see what features are supported go to http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html"
       end
 
       class JobWrapper < Qu::Job #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/que_adapter.rb b/activejob/lib/active_job/queue_adapters/que_adapter.rb
index e501fe0368..ab13689747 100644
--- a/activejob/lib/active_job/queue_adapters/que_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/que_adapter.rb
@@ -15,14 +15,16 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :que
     class QueAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          JobWrapper.enqueue job.serialize, queue: job.queue_name
-        end
+      def enqueue(job) #:nodoc:
+        que_job = JobWrapper.enqueue job.serialize, priority: job.priority
+        job.provider_job_id = que_job.attrs["job_id"]
+        que_job
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          JobWrapper.enqueue job.serialize, queue: job.queue_name, run_at: Time.at(timestamp)
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        que_job = JobWrapper.enqueue job.serialize, priority: job.priority, run_at: Time.at(timestamp)
+        job.provider_job_id = que_job.attrs["job_id"]
+        que_job
       end
 
       class JobWrapper < Que::Job #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb b/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
index 34c11a68b2..0ee41407d8 100644
--- a/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
@@ -17,29 +17,31 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :queue_classic
     class QueueClassicAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          build_queue(job.queue_name).enqueue("#{JobWrapper.name}.perform", job.serialize)
-        end
+      def enqueue(job) #:nodoc:
+        qc_job = build_queue(job.queue_name).enqueue("#{JobWrapper.name}.perform", job.serialize)
+        job.provider_job_id = qc_job["id"] if qc_job.is_a?(Hash)
+        qc_job
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          queue = build_queue(job.queue_name)
-          unless queue.respond_to?(:enqueue_at)
-            raise NotImplementedError, 'To be able to schedule jobs with queue_classic ' \
-              'the QC::Queue needs to respond to `enqueue_at(timestamp, method, *args)`. ' \
-              'You can implement this yourself or you can use the queue_classic-later gem.'
-          end
-          queue.enqueue_at(timestamp, "#{JobWrapper.name}.perform", job.serialize)
+      def enqueue_at(job, timestamp) #:nodoc:
+        queue = build_queue(job.queue_name)
+        unless queue.respond_to?(:enqueue_at)
+          raise NotImplementedError, 'To be able to schedule jobs with queue_classic ' \
+            'the QC::Queue needs to respond to `enqueue_at(timestamp, method, *args)`. ' \
+            'You can implement this yourself or you can use the queue_classic-later gem.'
         end
+        qc_job = queue.enqueue_at(timestamp, "#{JobWrapper.name}.perform", job.serialize)
+        job.provider_job_id = qc_job["id"] if qc_job.is_a?(Hash)
+        qc_job
+      end
 
-        # Builds a <tt>QC::Queue</tt> object to schedule jobs on.
-        #
-        # If you have a custom <tt>QC::Queue</tt> subclass you'll need to subclass
-        # <tt>ActiveJob::QueueAdapters::QueueClassicAdapter</tt> and override the
-        # <tt>build_queue</tt> method.
-        def build_queue(queue_name)
-          QC::Queue.new(queue_name)
-        end
+      # Builds a <tt>QC::Queue</tt> object to schedule jobs on.
+      #
+      # If you have a custom <tt>QC::Queue</tt> subclass you'll need to subclass
+      # <tt>ActiveJob::QueueAdapters::QueueClassicAdapter</tt> and override the
+      # <tt>build_queue</tt> method.
+      def build_queue(queue_name)
+        QC::Queue.new(queue_name)
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/resque_adapter.rb b/activejob/lib/active_job/queue_adapters/resque_adapter.rb
index 88c6b48fef..417854afd8 100644
--- a/activejob/lib/active_job/queue_adapters/resque_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/resque_adapter.rb
@@ -26,18 +26,16 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :resque
     class ResqueAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          Resque.enqueue_to job.queue_name, JobWrapper, job.serialize
-        end
+      def enqueue(job) #:nodoc:
+        Resque.enqueue_to job.queue_name, JobWrapper, job.serialize
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          unless Resque.respond_to?(:enqueue_at_with_queue)
-            raise NotImplementedError, "To be able to schedule jobs with Resque you need the " \
-              "resque-scheduler gem. Please add it to your Gemfile and run bundle install"
-          end
-          Resque.enqueue_at_with_queue job.queue_name, timestamp, JobWrapper, job.serialize
+      def enqueue_at(job, timestamp) #:nodoc:
+        unless Resque.respond_to?(:enqueue_at_with_queue)
+          raise NotImplementedError, "To be able to schedule jobs with Resque you need the " \
+            "resque-scheduler gem. Please add it to your Gemfile and run bundle install"
         end
+        Resque.enqueue_at_with_queue job.queue_name, timestamp, JobWrapper, job.serialize
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb b/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
index 21005fc728..c321776bf5 100644
--- a/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
@@ -15,22 +15,22 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :sidekiq
     class SidekiqAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          #Sidekiq::Client does not support symbols as keys
-          Sidekiq::Client.push \
-            'class' => JobWrapper,
-            'queue' => job.queue_name,
-            'args'  => [ job.serialize ]
-        end
+      def enqueue(job) #:nodoc:
+        #Sidekiq::Client does not support symbols as keys
+        job.provider_job_id = Sidekiq::Client.push \
+          'class'   => JobWrapper,
+          'wrapped' => job.class.to_s,
+          'queue'   => job.queue_name,
+          'args'    => [ job.serialize ]
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          Sidekiq::Client.push \
-            'class' => JobWrapper,
-            'queue' => job.queue_name,
-            'args'  => [ job.serialize ],
-            'at'    => timestamp
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        job.provider_job_id = Sidekiq::Client.push \
+          'class'   => JobWrapper,
+          'wrapped' => job.class.to_s,
+          'queue'   => job.queue_name,
+          'args'    => [ job.serialize ],
+          'at'      => timestamp
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb b/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
index 6d60a2f303..d78bdecdcb 100644
--- a/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
@@ -1,5 +1,5 @@
 require 'sneakers'
-require 'thread'
+require 'monitor'
 
 module ActiveJob
   module QueueAdapters
@@ -16,19 +16,19 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :sneakers
     class SneakersAdapter
-      @monitor = Monitor.new
+      def initialize
+        @monitor = Monitor.new
+      end
 
-      class << self
-        def enqueue(job) #:nodoc:
-          @monitor.synchronize do
-            JobWrapper.from_queue job.queue_name
-            JobWrapper.enqueue ActiveSupport::JSON.encode(job.serialize)
-          end
+      def enqueue(job) #:nodoc:
+        @monitor.synchronize do
+          JobWrapper.from_queue job.queue_name
+          JobWrapper.enqueue ActiveSupport::JSON.encode(job.serialize)
         end
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          raise NotImplementedError
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        raise NotImplementedError, "This queueing backend does not support scheduling jobs. To see what features are supported go to http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html"
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb b/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
index be9e7fd03a..c6c35f8ab4 100644
--- a/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
@@ -18,14 +18,12 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :sucker_punch
     class SuckerPunchAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          JobWrapper.new.async.perform job.serialize
-        end
+      def enqueue(job) #:nodoc:
+        JobWrapper.new.async.perform job.serialize
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          raise NotImplementedError
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        raise NotImplementedError, "This queueing backend does not support scheduling jobs. To see what features are supported go to http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html"
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/test_adapter.rb b/activejob/lib/active_job/queue_adapters/test_adapter.rb
index ea9df9a063..9b7b7139f4 100644
--- a/activejob/lib/active_job/queue_adapters/test_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/test_adapter.rb
@@ -10,15 +10,9 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :test
     class TestAdapter
-      delegate :name, to: :class
-      attr_accessor(:perform_enqueued_jobs, :perform_enqueued_at_jobs)
+      attr_accessor(:perform_enqueued_jobs, :perform_enqueued_at_jobs, :filter)
       attr_writer(:enqueued_jobs, :performed_jobs)
 
-      def initialize
-        self.perform_enqueued_jobs = false
-        self.perform_enqueued_at_jobs = false
-      end
-
       # Provides a store of all the enqueued jobs with the TestAdapter so you can check them.
       def enqueued_jobs
         @enqueued_jobs ||= []
@@ -30,22 +24,37 @@ module ActiveJob
       end
 
       def enqueue(job) #:nodoc:
-        if perform_enqueued_jobs
-          performed_jobs << {job: job.class, args: job.serialize['arguments'], queue: job.queue_name}
-          Base.execute job.serialize
-        else
-          enqueued_jobs << {job: job.class, args: job.serialize['arguments'], queue: job.queue_name}
-        end
+        return if filtered?(job)
+
+        job_data = job_to_hash(job)
+        enqueue_or_perform(perform_enqueued_jobs, job, job_data)
       end
 
       def enqueue_at(job, timestamp) #:nodoc:
-        if perform_enqueued_at_jobs
-          performed_jobs << {job: job.class, args: job.serialize['arguments'], queue: job.queue_name, at: timestamp}
+        return if filtered?(job)
+
+        job_data = job_to_hash(job, at: timestamp)
+        enqueue_or_perform(perform_enqueued_at_jobs, job, job_data)
+      end
+
+      private
+
+      def job_to_hash(job, extras = {})
+        { job: job.class, args: job.serialize.fetch('arguments'), queue: job.queue_name }.merge!(extras)
+      end
+
+      def enqueue_or_perform(perform, job, job_data)
+        if perform
+          performed_jobs << job_data
           Base.execute job.serialize
         else
-          enqueued_jobs << {job: job.class, args: job.serialize['arguments'], queue: job.queue_name, at: timestamp}
+          enqueued_jobs << job_data
         end
       end
+
+      def filtered?(job)
+        filter && !Array(filter).include?(job.class)
+      end
     end
   end
 end
diff --git a/activejob/lib/active_job/queue_name.rb b/activejob/lib/active_job/queue_name.rb
index 9ae0345120..65786a49ff 100644
--- a/activejob/lib/active_job/queue_name.rb
+++ b/activejob/lib/active_job/queue_name.rb
@@ -39,7 +39,7 @@ module ActiveJob
       self.queue_name_delimiter = '_' # set default delimiter to '_'
     end
 
-    # Returns the name of the queue the job will be run on
+    # Returns the name of the queue the job will be run on.
     def queue_name
       if @queue_name.is_a?(Proc)
         @queue_name = self.class.queue_name_from_part(instance_exec(&@queue_name))
diff --git a/activejob/lib/active_job/queue_priority.rb b/activejob/lib/active_job/queue_priority.rb
new file mode 100644
index 0000000000..01d84910ff
--- /dev/null
+++ b/activejob/lib/active_job/queue_priority.rb
@@ -0,0 +1,44 @@
+module ActiveJob
+  module QueuePriority
+    extend ActiveSupport::Concern
+
+    # Includes the ability to override the default queue priority.
+    module ClassMethods
+      mattr_accessor(:default_priority)
+
+      # Specifies the priority of the queue to create the job with.
+      #
+      #   class PublishToFeedJob < ActiveJob::Base
+      #     queue_with_priority 50
+      #
+      #     def perform(post)
+      #       post.to_feed!
+      #     end
+      #   end
+      #
+      # Specify either an argument or a block.
+      def queue_with_priority(priority=nil, &block)
+        if block_given?
+          self.priority = block
+        else
+          self.priority = priority
+        end
+      end
+    end
+
+    included do
+      class_attribute :priority, instance_accessor: false
+
+      self.priority = default_priority
+    end
+
+    # Returns the priority that the job will be created with
+    def priority
+      if @priority.is_a?(Proc)
+        @priority = instance_exec(&@priority)
+      end
+      @priority
+    end
+
+  end
+end
diff --git a/activejob/lib/active_job/test_helper.rb b/activejob/lib/active_job/test_helper.rb
index d18656e398..44ddfa5f69 100644
--- a/activejob/lib/active_job/test_helper.rb
+++ b/activejob/lib/active_job/test_helper.rb
@@ -1,3 +1,4 @@
+require 'active_support/core_ext/class/subclasses'
 require 'active_support/core_ext/hash/keys'
 
 module ActiveJob
@@ -6,17 +7,28 @@ module ActiveJob
     extend ActiveSupport::Concern
 
     included do
-      def before_setup
-        @old_queue_adapter  = queue_adapter
-        ActiveJob::Base.queue_adapter = :test
+      def before_setup # :nodoc:
+        test_adapter = ActiveJob::QueueAdapters::TestAdapter.new
+
+        @old_queue_adapters = (ActiveJob::Base.subclasses << ActiveJob::Base).select do |klass|
+          # only override explicitly set adapters, a quirk of `class_attribute`
+          klass.singleton_class.public_instance_methods(false).include?(:_queue_adapter)
+        end.map do |klass|
+          [klass, klass.queue_adapter].tap do
+            klass.queue_adapter = test_adapter
+          end
+        end
+
         clear_enqueued_jobs
         clear_performed_jobs
         super
       end
 
-      def after_teardown
+      def after_teardown # :nodoc:
         super
-        ActiveJob::Base.queue_adapter = @old_queue_adapter
+        @old_queue_adapters.each do |(klass, adapter)|
+          klass.queue_adapter = adapter
+        end
       end
 
       # Asserts that the number of enqueued jobs matches the given number.
@@ -56,7 +68,7 @@ module ActiveJob
           original_count = enqueued_jobs_size(only: only)
           yield
           new_count = enqueued_jobs_size(only: only)
-          assert_equal original_count + number, new_count, "#{number} jobs expected, but #{new_count - original_count} were enqueued"
+          assert_equal number, new_count - original_count, "#{number} jobs expected, but #{new_count - original_count} were enqueued"
         else
           actual_count = enqueued_jobs_size(only: only)
           assert_equal number, actual_count, "#{number} jobs expected, but #{actual_count} were enqueued"
@@ -125,12 +137,34 @@ module ActiveJob
       #       HelloJob.perform_later('sean')
       #     end
       #   end
-      def assert_performed_jobs(number)
+      #
+      # The block form supports filtering. If the :only option is specified,
+      # then only the listed job(s) will be performed.
+      #
+      #     def test_hello_job
+      #       assert_performed_jobs 1, only: HelloJob do
+      #         HelloJob.perform_later('jeremy')
+      #         LoggingJob.perform_later
+      #       end
+      #     end
+      #
+      # An array may also be specified, to support testing multiple jobs.
+      #
+      #     def test_hello_and_logging_jobs
+      #       assert_nothing_raised do
+      #         assert_performed_jobs 2, only: [HelloJob, LoggingJob] do
+      #           HelloJob.perform_later('jeremy')
+      #           LoggingJob.perform_later('stewie')
+      #           RescueJob.perform_later('david')
+      #         end
+      #       end
+      #     end
+      def assert_performed_jobs(number, only: nil)
         if block_given?
           original_count = performed_jobs.size
-          perform_enqueued_jobs { yield }
+          perform_enqueued_jobs(only: only) { yield }
           new_count = performed_jobs.size
-          assert_equal original_count + number, new_count,
+          assert_equal number, new_count - original_count,
                        "#{number} jobs expected, but #{new_count - original_count} were performed"
         else
           performed_jobs_size = performed_jobs.size
@@ -157,11 +191,33 @@ module ActiveJob
       #     end
       #   end
       #
+      # The block form supports filtering. If the :only option is specified,
+      # then only the listed job(s) will be performed.
+      #
+      #     def test_hello_job
+      #       assert_performed_jobs 1, only: HelloJob do
+      #         HelloJob.perform_later('jeremy')
+      #         LoggingJob.perform_later
+      #       end
+      #     end
+      #
+      # An array may also be specified, to support testing multiple jobs.
+      #
+      #     def test_hello_and_logging_jobs
+      #       assert_nothing_raised do
+      #         assert_performed_jobs 2, only: [HelloJob, LoggingJob] do
+      #           HelloJob.perform_later('jeremy')
+      #           LoggingJob.perform_later('stewie')
+      #           RescueJob.perform_later('david')
+      #         end
+      #       end
+      #     end
+      #
       # Note: This assertion is simply a shortcut for:
       #
       #   assert_performed_jobs 0, &block
-      def assert_no_performed_jobs(&block)
-        assert_performed_jobs 0, &block
+      def assert_no_performed_jobs(only: nil, &block)
+        assert_performed_jobs 0, only: only, &block
       end
 
       # Asserts that the job passed in the block has been enqueued with the given arguments.
@@ -170,18 +226,22 @@ module ActiveJob
       #     assert_enqueued_with(job: MyJob, args: [1,2,3], queue: 'low') do
       #       MyJob.perform_later(1,2,3)
       #     end
+      #
+      #     assert_enqueued_with(job: MyJob, at: Date.tomorrow.noon) do
+      #       MyJob.set(wait_until: Date.tomorrow.noon).perform_later
+      #     end
       #   end
-      def assert_enqueued_with(args = {}, &_block)
-        original_enqueued_jobs = enqueued_jobs.dup
-        clear_enqueued_jobs
+      def assert_enqueued_with(args = {})
+        original_enqueued_jobs_count = enqueued_jobs.count
         args.assert_valid_keys(:job, :args, :at, :queue)
+        serialized_args = serialize_args_for_assertion(args)
         yield
-        matching_job = enqueued_jobs.any? do |job|
-          args.all? { |key, value| value == job[key] }
+        in_block_jobs = enqueued_jobs.drop(original_enqueued_jobs_count)
+        matching_job = in_block_jobs.find do |job|
+          serialized_args.all? { |key, value| value == job[key] }
         end
         assert matching_job, "No enqueued job found with #{args}"
-      ensure
-        queue_adapter.enqueued_jobs = original_enqueued_jobs + enqueued_jobs
+        instantiate_job(matching_job)
       end
 
       # Asserts that the job passed in the block has been performed with the given arguments.
@@ -190,29 +250,39 @@ module ActiveJob
       #     assert_performed_with(job: MyJob, args: [1,2,3], queue: 'high') do
       #       MyJob.perform_later(1,2,3)
       #     end
+      #
+      #     assert_performed_with(job: MyJob, at: Date.tomorrow.noon) do
+      #       MyJob.set(wait_until: Date.tomorrow.noon).perform_later
+      #     end
       #   end
-      def assert_performed_with(args = {}, &_block)
-        original_performed_jobs = performed_jobs.dup
-        clear_performed_jobs
+      def assert_performed_with(args = {})
+        original_performed_jobs_count = performed_jobs.count
         args.assert_valid_keys(:job, :args, :at, :queue)
+        serialized_args = serialize_args_for_assertion(args)
         perform_enqueued_jobs { yield }
-        matching_job = performed_jobs.any? do |job|
-          args.all? { |key, value| value == job[key] }
+        in_block_jobs = performed_jobs.drop(original_performed_jobs_count)
+        matching_job = in_block_jobs.find do |job|
+          serialized_args.all? { |key, value| value == job[key] }
         end
         assert matching_job, "No performed job found with #{args}"
-      ensure
-        queue_adapter.performed_jobs = original_performed_jobs + performed_jobs
+        instantiate_job(matching_job)
       end
 
-      def perform_enqueued_jobs
-        @old_perform_enqueued_jobs = queue_adapter.perform_enqueued_jobs
-        @old_perform_enqueued_at_jobs = queue_adapter.perform_enqueued_at_jobs
-        queue_adapter.perform_enqueued_jobs = true
-        queue_adapter.perform_enqueued_at_jobs = true
-        yield
-      ensure
-        queue_adapter.perform_enqueued_jobs = @old_perform_enqueued_jobs
-        queue_adapter.perform_enqueued_at_jobs = @old_perform_enqueued_at_jobs
+      def perform_enqueued_jobs(only: nil)
+        old_perform_enqueued_jobs = queue_adapter.perform_enqueued_jobs
+        old_perform_enqueued_at_jobs = queue_adapter.perform_enqueued_at_jobs
+        old_filter = queue_adapter.filter
+
+        begin
+          queue_adapter.perform_enqueued_jobs = true
+          queue_adapter.perform_enqueued_at_jobs = true
+          queue_adapter.filter = only
+          yield
+        ensure
+          queue_adapter.perform_enqueued_jobs = old_perform_enqueued_jobs
+          queue_adapter.perform_enqueued_at_jobs = old_perform_enqueued_at_jobs
+          queue_adapter.filter = old_filter
+        end
       end
 
       def queue_adapter
@@ -224,21 +294,35 @@ module ActiveJob
                to: :queue_adapter
 
       private
-        def clear_enqueued_jobs
+        def clear_enqueued_jobs # :nodoc:
           enqueued_jobs.clear
         end
 
-        def clear_performed_jobs
+        def clear_performed_jobs # :nodoc:
           performed_jobs.clear
         end
 
-        def enqueued_jobs_size(only: nil)
+        def enqueued_jobs_size(only: nil) # :nodoc:
           if only
-            enqueued_jobs.select { |job| job[:job] == only }.size
+            enqueued_jobs.count { |job| Array(only).include?(job.fetch(:job)) }
           else
-            enqueued_jobs.size
+            enqueued_jobs.count
+          end
+        end
+
+        def serialize_args_for_assertion(args) # :nodoc:
+          args.dup.tap do |serialized_args|
+            serialized_args[:args] = ActiveJob::Arguments.serialize(serialized_args[:args]) if serialized_args[:args]
+            serialized_args[:at]   = serialized_args[:at].to_f if serialized_args[:at]
           end
         end
+
+        def instantiate_job(payload) # :nodoc:
+          job = payload[:job].new(*payload[:args])
+          job.scheduled_at = Time.at(payload[:at]) if payload.key?(:at)
+          job.queue_name = payload[:queue]
+          job
+        end
     end
   end
 end
diff --git a/activejob/lib/active_job/translation.rb b/activejob/lib/active_job/translation.rb
new file mode 100644
index 0000000000..67e4cf4ab9
--- /dev/null
+++ b/activejob/lib/active_job/translation.rb
@@ -0,0 +1,11 @@
+module ActiveJob
+  module Translation #:nodoc:
+    extend ActiveSupport::Concern
+
+    included do
+      around_perform do |job, block, _|
+        I18n.with_locale(job.locale, &block)
+      end
+    end
+  end
+end
diff --git a/activejob/lib/rails/generators/job/job_generator.rb b/activejob/lib/rails/generators/job/job_generator.rb
index 979ffcb748..2115fb9f71 100644
--- a/activejob/lib/rails/generators/job/job_generator.rb
+++ b/activejob/lib/rails/generators/job/job_generator.rb
@@ -1,6 +1,6 @@
 require 'rails/generators/named_base'
 
-module Rails
+module Rails # :nodoc:
   module Generators # :nodoc:
     class JobGenerator < Rails::Generators::NamedBase # :nodoc:
       desc 'This generator creates an active job file at app/jobs'
@@ -18,7 +18,6 @@ module Rails
       def create_job_file
         template 'job.rb', File.join('app/jobs', class_path, "#{file_name}_job.rb")
       end
-
     end
   end
 end
diff --git a/activejob/lib/rails/generators/job/templates/job.rb b/activejob/lib/rails/generators/job/templates/job.rb
index 462c71d917..4ad2914a45 100644
--- a/activejob/lib/rails/generators/job/templates/job.rb
+++ b/activejob/lib/rails/generators/job/templates/job.rb
@@ -1,5 +1,5 @@
 <% module_namespacing do -%>
-class <%= class_name %>Job < ActiveJob::Base
+class <%= class_name %>Job < ApplicationJob
   queue_as :<%= options[:queue] %>
 
   def perform(*args)
diff --git a/activejob/test/adapters/async.rb b/activejob/test/adapters/async.rb
new file mode 100644
index 0000000000..df58027599
--- /dev/null
+++ b/activejob/test/adapters/async.rb
@@ -0,0 +1,5 @@
+require 'concurrent'
+require 'active_job/async_job'
+
+ActiveJob::Base.queue_adapter = :async
+ActiveJob::AsyncJob.perform_immediately!
diff --git a/activejob/test/cases/adapter_test.rb b/activejob/test/cases/adapter_test.rb
index 6570c55a83..6d75ae9a7c 100644
--- a/activejob/test/cases/adapter_test.rb
+++ b/activejob/test/cases/adapter_test.rb
@@ -1,7 +1,7 @@
 require 'helper'
 
 class AdapterTest < ActiveSupport::TestCase
-  test "should load #{ENV['AJADAPTER']} adapter" do
-    assert_equal "active_job/queue_adapters/#{ENV['AJADAPTER']}_adapter".classify, ActiveJob::Base.queue_adapter.name
+  test "should load #{ENV['AJ_ADAPTER']} adapter" do
+    assert_equal "active_job/queue_adapters/#{ENV['AJ_ADAPTER']}_adapter".classify, ActiveJob::Base.queue_adapter.class.name
   end
 end
diff --git a/activejob/test/cases/argument_serialization_test.rb b/activejob/test/cases/argument_serialization_test.rb
index dbe36fc572..933972a52b 100644
--- a/activejob/test/cases/argument_serialization_test.rb
+++ b/activejob/test/cases/argument_serialization_test.rb
@@ -2,6 +2,7 @@ require 'helper'
 require 'active_job/arguments'
 require 'models/person'
 require 'active_support/core_ext/hash/indifferent_access'
+require 'jobs/kwargs_job'
 
 class ArgumentSerializationTest < ActiveSupport::TestCase
   setup do
@@ -31,16 +32,26 @@ class ArgumentSerializationTest < ActiveSupport::TestCase
   end
 
   test 'should convert records to Global IDs' do
-    assert_arguments_roundtrip [@person], ['_aj_globalid' => @person.to_gid.to_s]
+    assert_arguments_roundtrip [@person]
   end
 
   test 'should dive deep into arrays and hashes' do
-    assert_arguments_roundtrip [3, [@person]], [3, ['_aj_globalid' => @person.to_gid.to_s]]
-    assert_arguments_roundtrip [{ 'a' => @person }], [{ 'a' => { '_aj_globalid' => @person.to_gid.to_s }}.with_indifferent_access]
+    assert_arguments_roundtrip [3, [@person]]
+    assert_arguments_roundtrip [{ 'a' => @person }]
   end
 
-  test 'should stringify symbol hash keys' do
-    assert_equal [ 'a' => 1 ], ActiveJob::Arguments.serialize([ a: 1 ])
+  test 'should maintain string and symbol keys' do
+    assert_arguments_roundtrip([a: 1, "b" => 2])
+  end
+
+  test 'should maintain hash with indifferent access' do
+    symbol_key = { a: 1 }
+    string_key = { 'a' => 1 }
+    indifferent_access = { a: 1 }.with_indifferent_access
+
+    assert_not_instance_of ActiveSupport::HashWithIndifferentAccess, perform_round_trip([symbol_key]).first
+    assert_not_instance_of ActiveSupport::HashWithIndifferentAccess, perform_round_trip([string_key]).first
+    assert_instance_of ActiveSupport::HashWithIndifferentAccess, perform_round_trip([indifferent_access]).first
   end
 
   test 'should disallow non-string/symbol hash keys' do
@@ -71,14 +82,29 @@ class ArgumentSerializationTest < ActiveSupport::TestCase
     end
   end
 
+  test 'allows for keyword arguments' do
+    KwargsJob.perform_later(argument: 2)
+
+    assert_equal "Job with argument: 2", JobBuffer.last_value
+  end
+
+  test 'raises a friendly SerializationError for records without ids' do
+    err = assert_raises ActiveJob::SerializationError do
+      ActiveJob::Arguments.serialize [Person.new(nil)]
+    end
+    assert_match 'Unable to serialize Person without an id.', err.message
+  end
+
   private
     def assert_arguments_unchanged(*args)
-      assert_arguments_roundtrip args, args
+      assert_arguments_roundtrip args
+    end
+
+    def assert_arguments_roundtrip(args)
+      assert_equal args, perform_round_trip(args)
     end
 
-    def assert_arguments_roundtrip(args, expected_serialized_args)
-      serialized = ActiveJob::Arguments.serialize(args)
-      assert_equal expected_serialized_args, serialized
-      assert_equal args, ActiveJob::Arguments.deserialize(serialized)
+    def perform_round_trip(args)
+      ActiveJob::Arguments.deserialize(ActiveJob::Arguments.serialize(args))
     end
 end
diff --git a/activejob/test/cases/async_job_test.rb b/activejob/test/cases/async_job_test.rb
new file mode 100644
index 0000000000..2642cfc608
--- /dev/null
+++ b/activejob/test/cases/async_job_test.rb
@@ -0,0 +1,42 @@
+require 'helper'
+require 'jobs/hello_job'
+require 'jobs/queue_as_job'
+
+class AsyncJobTest < ActiveSupport::TestCase
+  def using_async_adapter?
+    ActiveJob::Base.queue_adapter.is_a? ActiveJob::QueueAdapters::AsyncAdapter
+  end
+
+  setup do
+    ActiveJob::AsyncJob.perform_asynchronously!
+  end
+
+  teardown do
+    ActiveJob::AsyncJob::QUEUES.clear
+    ActiveJob::AsyncJob.perform_immediately!
+  end
+
+  test "#create_thread_pool returns a thread_pool" do
+    thread_pool = ActiveJob::AsyncJob.create_thread_pool
+    assert thread_pool.is_a? Concurrent::ExecutorService
+    assert_not thread_pool.is_a? Concurrent::ImmediateExecutor
+  end
+
+  test "#create_thread_pool returns an ImmediateExecutor after #perform_immediately! is called" do
+    ActiveJob::AsyncJob.perform_immediately!
+    thread_pool = ActiveJob::AsyncJob.create_thread_pool
+    assert thread_pool.is_a? Concurrent::ImmediateExecutor
+  end
+
+  test "enqueuing without specifying a queue uses the default queue" do
+    skip unless using_async_adapter?
+    HelloJob.perform_later
+    assert ActiveJob::AsyncJob::QUEUES.key? 'default'
+  end
+
+  test "enqueuing to a queue that does not exist creates the queue" do
+    skip unless using_async_adapter?
+    QueueAsJob.perform_later
+    assert ActiveJob::AsyncJob::QUEUES.key? QueueAsJob::MY_QUEUE.to_s
+  end
+end
diff --git a/activejob/test/cases/job_serialization_test.rb b/activejob/test/cases/job_serialization_test.rb
index db22783030..229517774e 100644
--- a/activejob/test/cases/job_serialization_test.rb
+++ b/activejob/test/cases/job_serialization_test.rb
@@ -1,5 +1,6 @@
 require 'helper'
 require 'jobs/gid_job'
+require 'jobs/hello_job'
 require 'models/person'
 
 class JobSerializationTest < ActiveSupport::TestCase
@@ -12,4 +13,20 @@ class JobSerializationTest < ActiveSupport::TestCase
     GidJob.perform_later @person
     assert_equal "Person with ID: 5", JobBuffer.last_value
   end
+
+  test 'serialize includes current locale' do
+    assert_equal :en, HelloJob.new.serialize['locale']
+  end
+
+  test 'deserialize sets locale' do
+    job = HelloJob.new
+    job.deserialize 'locale' => :es
+    assert_equal :es, job.locale
+  end
+
+  test 'deserialize sets default locale' do
+    job = HelloJob.new
+    job.deserialize({})
+    assert_equal :en, job.locale
+  end
 end
diff --git a/activejob/test/cases/logging_test.rb b/activejob/test/cases/logging_test.rb
index 64aae00441..820e9112de 100644
--- a/activejob/test/cases/logging_test.rb
+++ b/activejob/test/cases/logging_test.rb
@@ -6,7 +6,7 @@ require 'jobs/logging_job'
 require 'jobs/nested_job'
 require 'models/person'
 
-class AdapterTest < ActiveSupport::TestCase
+class LoggingTest < ActiveSupport::TestCase
   include ActiveSupport::LogSubscriber::TestHelper
   include ActiveSupport::Logger::Severity
 
@@ -74,6 +74,14 @@ class AdapterTest < ActiveSupport::TestCase
     assert_match(%r{Performing.*gid://aj/Person/123}, @logger.messages)
   end
 
+  def test_globalid_nested_parameter_logging
+    person = Person.new(123)
+    LoggingJob.perform_later(person: person)
+    assert_match(%r{Enqueued.*gid://aj/Person/123}, @logger.messages)
+    assert_match(%r{Dummy, here is it: .*#<Person:.*>}, @logger.messages)
+    assert_match(%r{Performing.*gid://aj/Person/123}, @logger.messages)
+  end
+
   def test_enqueue_job_logging
     HelloJob.perform_later "Cristian"
     assert_match(/Enqueued HelloJob \(Job ID: .*?\) to .*?:.*Cristian/, @logger.messages)
diff --git a/activejob/test/cases/queue_adapter_test.rb b/activejob/test/cases/queue_adapter_test.rb
new file mode 100644
index 0000000000..fb3fdc392f
--- /dev/null
+++ b/activejob/test/cases/queue_adapter_test.rb
@@ -0,0 +1,56 @@
+require 'helper'
+
+module ActiveJob
+  module QueueAdapters
+    class StubOneAdapter
+      def enqueue(*); end
+      def enqueue_at(*); end
+    end
+
+    class StubTwoAdapter
+      def enqueue(*); end
+      def enqueue_at(*); end
+    end
+  end
+end
+
+class QueueAdapterTest < ActiveJob::TestCase
+  test 'should forbid nonsense arguments' do
+    assert_raises(ArgumentError) { ActiveJob::Base.queue_adapter = Mutex }
+    assert_raises(ArgumentError) { ActiveJob::Base.queue_adapter = Mutex.new }
+  end
+
+  test 'should warn on passing an adapter class' do
+    klass = Class.new do
+      def self.name
+        'fake'
+      end
+
+      def enqueue(*); end
+      def enqueue_at(*); end
+    end
+
+    assert_deprecated { ActiveJob::Base.queue_adapter = klass }
+  end
+
+  test 'should allow overriding the queue_adapter at the child class level without affecting the parent or its sibling' do
+    base_queue_adapter = ActiveJob::Base.queue_adapter
+
+    child_job_one = Class.new(ActiveJob::Base)
+    child_job_one.queue_adapter = :stub_one
+
+    assert_not_equal ActiveJob::Base.queue_adapter, child_job_one.queue_adapter
+    assert_kind_of ActiveJob::QueueAdapters::StubOneAdapter, child_job_one.queue_adapter
+
+    child_job_two = Class.new(ActiveJob::Base)
+    child_job_two.queue_adapter = :stub_two
+
+    assert_kind_of ActiveJob::QueueAdapters::StubTwoAdapter, child_job_two.queue_adapter
+    assert_kind_of ActiveJob::QueueAdapters::StubOneAdapter, child_job_one.queue_adapter, "child_job_one's queue adapter should remain unchanged"
+    assert_equal base_queue_adapter, ActiveJob::Base.queue_adapter, "ActiveJob::Base's queue adapter should remain unchanged"
+
+    child_job_three = Class.new(ActiveJob::Base)
+
+    assert_not_nil child_job_three.queue_adapter
+  end
+end
diff --git a/activejob/test/cases/queue_priority_test.rb b/activejob/test/cases/queue_priority_test.rb
new file mode 100644
index 0000000000..ca17b51dad
--- /dev/null
+++ b/activejob/test/cases/queue_priority_test.rb
@@ -0,0 +1,47 @@
+require 'helper'
+require 'jobs/hello_job'
+
+class QueuePriorityTest < ActiveSupport::TestCase
+  test 'priority unset by default' do
+    assert_equal nil, HelloJob.priority
+  end
+
+  test 'uses given priority' do
+    original_priority = HelloJob.priority
+
+    begin
+      HelloJob.queue_with_priority 90
+      assert_equal 90, HelloJob.new.priority
+    ensure
+      HelloJob.priority = original_priority
+    end
+  end
+
+  test 'evals block given to priority to determine priority' do
+    original_priority = HelloJob.priority
+
+    begin
+      HelloJob.queue_with_priority { 25 }
+      assert_equal 25, HelloJob.new.priority
+    ensure
+      HelloJob.priority = original_priority
+    end
+  end
+
+  test 'can use arguments to determine priority in priority block' do
+    original_priority = HelloJob.priority
+
+    begin
+      HelloJob.queue_with_priority { self.arguments.first=='1' ? 99 : 11 }
+      assert_equal 99, HelloJob.new('1').priority
+      assert_equal 11, HelloJob.new('3').priority
+    ensure
+      HelloJob.priority = original_priority
+    end
+  end
+
+  test 'uses priority passed to #set' do
+    job = HelloJob.set(priority: 123).perform_later
+    assert_equal 123, job.priority
+  end
+end
diff --git a/activejob/test/cases/test_case_test.rb b/activejob/test/cases/test_case_test.rb
index 1d0fdbd22d..616454a4b6 100644
--- a/activejob/test/cases/test_case_test.rb
+++ b/activejob/test/cases/test_case_test.rb
@@ -4,11 +4,20 @@ require 'jobs/logging_job'
 require 'jobs/nested_job'
 
 class ActiveJobTestCaseTest < ActiveJob::TestCase
+  # this tests that this job class doesn't get its adapter set.
+  # that's the correct behavior since we don't want to break
+  # the `class_attribute` inheritance
+  class TestClassAttributeInheritanceJob < ActiveJob::Base
+    def self.queue_adapter=(*)
+      raise 'Attempting to break `class_attribute` inheritance, bad!'
+    end
+  end
+
   def test_include_helper
     assert_includes self.class.ancestors, ActiveJob::TestHelper
   end
 
   def test_set_test_adapter
-    assert_instance_of ActiveJob::QueueAdapters::TestAdapter, self.queue_adapter
+    assert_kind_of ActiveJob::QueueAdapters::TestAdapter, self.queue_adapter
   end
 end
diff --git a/activejob/test/cases/test_helper_test.rb b/activejob/test/cases/test_helper_test.rb
index f34638e7d8..f7ee763e8a 100644
--- a/activejob/test/cases/test_helper_test.rb
+++ b/activejob/test/cases/test_helper_test.rb
@@ -4,6 +4,8 @@ require 'active_support/core_ext/date'
 require 'jobs/hello_job'
 require 'jobs/logging_job'
 require 'jobs/nested_job'
+require 'jobs/rescue_job'
+require 'models/person'
 
 class EnqueuedJobsTest < ActiveJob::TestCase
   def test_assert_enqueued_jobs
@@ -29,6 +31,17 @@ class EnqueuedJobsTest < ActiveJob::TestCase
     end
   end
 
+  def test_assert_enqueued_jobs_message
+    HelloJob.perform_later('sean')
+    e = assert_raises Minitest::Assertion do
+      assert_enqueued_jobs 2 do
+        HelloJob.perform_later('sean')
+      end
+    end
+    assert_match "Expected: 2", e.message
+    assert_match "Actual: 1", e.message
+  end
+
   def test_assert_enqueued_jobs_with_no_block
     assert_nothing_raised do
       HelloJob.perform_later('rafael')
@@ -127,6 +140,16 @@ class EnqueuedJobsTest < ActiveJob::TestCase
     assert_match(/1 .* but 2/, error.message)
   end
 
+  def test_assert_enqueued_jobs_with_only_option_as_array
+    assert_nothing_raised do
+      assert_enqueued_jobs 2, only: [HelloJob, LoggingJob] do
+        HelloJob.perform_later('jeremy')
+        LoggingJob.perform_later('stewie')
+        RescueJob.perform_later('david')
+      end
+    end
+  end
+
   def test_assert_no_enqueued_jobs_with_only_option
     assert_nothing_raised do
       assert_no_enqueued_jobs only: HelloJob do
@@ -146,12 +169,31 @@ class EnqueuedJobsTest < ActiveJob::TestCase
     assert_match(/0 .* but 1/, error.message)
   end
 
+  def test_assert_no_enqueued_jobs_with_only_option_as_array
+    assert_nothing_raised do
+      assert_no_enqueued_jobs only: [HelloJob, RescueJob] do
+        LoggingJob.perform_later
+      end
+    end
+  end
+
   def test_assert_enqueued_job
     assert_enqueued_with(job: LoggingJob, queue: 'default') do
       LoggingJob.set(wait_until: Date.tomorrow.noon).perform_later
     end
   end
 
+  def test_assert_enqueued_job_returns
+    job = assert_enqueued_with(job: LoggingJob) do
+      LoggingJob.set(wait_until: 5.minutes.from_now).perform_later(1, 2, 3)
+    end
+
+    assert_instance_of LoggingJob, job
+    assert_in_delta 5.minutes.from_now, job.scheduled_at, 1
+    assert_equal 'default', job.queue_name
+    assert_equal [1, 2, 3], job.arguments
+  end
+
   def test_assert_enqueued_job_failure
     assert_raise ActiveSupport::TestCase::Assertion do
       assert_enqueued_with(job: LoggingJob, queue: 'default') do
@@ -175,9 +217,51 @@ class EnqueuedJobsTest < ActiveJob::TestCase
       end
     end
   end
+
+  def test_assert_enqueued_job_with_at_option
+    assert_enqueued_with(job: HelloJob, at: Date.tomorrow.noon) do
+      HelloJob.set(wait_until: Date.tomorrow.noon).perform_later
+    end
+  end
+
+  def test_assert_enqueued_job_with_global_id_args
+    ricardo = Person.new(9)
+    assert_enqueued_with(job: HelloJob, args: [ricardo]) do
+      HelloJob.perform_later(ricardo)
+    end
+  end
+
+  def test_assert_enqueued_job_failure_with_global_id_args
+    ricardo = Person.new(9)
+    wilma = Person.new(11)
+    error = assert_raise ActiveSupport::TestCase::Assertion do
+      assert_enqueued_with(job: HelloJob, args: [wilma]) do
+        HelloJob.perform_later(ricardo)
+      end
+    end
+
+    assert_equal "No enqueued job found with {:job=>HelloJob, :args=>[#{wilma.inspect}]}", error.message
+  end
+
+  def test_assert_enqueued_job_does_not_change_jobs_count
+    HelloJob.perform_later
+    assert_enqueued_with(job: HelloJob) do
+      HelloJob.perform_later
+    end
+
+    assert_equal 2, ActiveJob::Base.queue_adapter.enqueued_jobs.count
+  end
 end
 
 class PerformedJobsTest < ActiveJob::TestCase
+  def test_performed_enqueue_jobs_with_only_option_doesnt_leak_outside_the_block
+    assert_equal nil, queue_adapter.filter
+    perform_enqueued_jobs only: HelloJob do
+      assert_equal HelloJob, queue_adapter.filter
+    end
+    assert_equal nil, queue_adapter.filter
+  end
+
   def test_assert_performed_jobs
     assert_nothing_raised do
       assert_performed_jobs 1 do
@@ -201,6 +285,17 @@ class PerformedJobsTest < ActiveJob::TestCase
     end
   end
 
+  def test_assert_performed_jobs_message
+    HelloJob.perform_later('sean')
+    e = assert_raises Minitest::Assertion do
+      assert_performed_jobs 2 do
+        HelloJob.perform_later('sean')
+      end
+    end
+    assert_match "Expected: 2", e.message
+    assert_match "Actual: 1", e.message
+  end
+
   def test_assert_performed_jobs_with_no_block
     assert_nothing_raised do
       perform_enqueued_jobs do
@@ -263,23 +358,154 @@ class PerformedJobsTest < ActiveJob::TestCase
     assert_match(/0 .* but 1/, error.message)
   end
 
+  def test_assert_performed_jobs_with_only_option
+    assert_nothing_raised do
+      assert_performed_jobs 1, only: HelloJob do
+        HelloJob.perform_later('jeremy')
+        LoggingJob.perform_later
+      end
+    end
+  end
+
+  def test_assert_performed_jobs_with_only_option_as_array
+    assert_nothing_raised do
+      assert_performed_jobs 2, only: [HelloJob, LoggingJob] do
+        HelloJob.perform_later('jeremy')
+        LoggingJob.perform_later('stewie')
+        RescueJob.perform_later('david')
+      end
+    end
+  end
+
+  def test_assert_performed_jobs_with_only_option_and_none_sent
+    error = assert_raise ActiveSupport::TestCase::Assertion do
+      assert_performed_jobs 1, only: HelloJob do
+        LoggingJob.perform_later
+      end
+    end
+
+    assert_match(/1 .* but 0/, error.message)
+  end
+
+  def test_assert_performed_jobs_with_only_option_and_too_few_sent
+    error = assert_raise ActiveSupport::TestCase::Assertion do
+      assert_performed_jobs 5, only: HelloJob do
+        HelloJob.perform_later('jeremy')
+        4.times { LoggingJob.perform_later }
+      end
+    end
+
+    assert_match(/5 .* but 1/, error.message)
+  end
+
+  def test_assert_performed_jobs_with_only_option_and_too_many_sent
+    error = assert_raise ActiveSupport::TestCase::Assertion do
+      assert_performed_jobs 1, only: HelloJob do
+        2.times { HelloJob.perform_later('jeremy') }
+      end
+    end
+
+    assert_match(/1 .* but 2/, error.message)
+  end
+
+  def test_assert_no_performed_jobs_with_only_option
+    assert_nothing_raised do
+      assert_no_performed_jobs only: HelloJob do
+        LoggingJob.perform_later
+      end
+    end
+  end
+
+  def test_assert_no_performed_jobs_with_only_option_as_array
+    assert_nothing_raised do
+      assert_no_performed_jobs only: [HelloJob, RescueJob] do
+        LoggingJob.perform_later
+      end
+    end
+  end
+
+  def test_assert_no_performed_jobs_with_only_option_failure
+    error = assert_raise ActiveSupport::TestCase::Assertion do
+      assert_no_performed_jobs only: HelloJob do
+        HelloJob.perform_later('jeremy')
+        LoggingJob.perform_later
+      end
+    end
+
+    assert_match(/0 .* but 1/, error.message)
+  end
+
   def test_assert_performed_job
     assert_performed_with(job: NestedJob, queue: 'default') do
       NestedJob.perform_later
     end
   end
 
+  def test_assert_performed_job_returns
+    job = assert_performed_with(job: NestedJob, queue: 'default') do
+      NestedJob.perform_later
+    end
+
+    assert_instance_of NestedJob, job
+    assert_nil job.scheduled_at
+    assert_equal [], job.arguments
+    assert_equal 'default', job.queue_name
+  end
+
   def test_assert_performed_job_failure
     assert_raise ActiveSupport::TestCase::Assertion do
-      assert_performed_with(job: LoggingJob, at: Date.tomorrow.noon, queue: 'default') do
-        NestedJob.set(wait_until: Date.tomorrow.noon).perform_later
+      assert_performed_with(job: LoggingJob) do
+        HelloJob.perform_later
       end
     end
 
     assert_raise ActiveSupport::TestCase::Assertion do
-      assert_performed_with(job: NestedJob, at: Date.tomorrow.noon, queue: 'low') do
-        NestedJob.set(queue: 'low', wait_until: Date.tomorrow.noon).perform_later
+      assert_performed_with(job: HelloJob, queue: 'low') do
+        HelloJob.set(queue: 'important').perform_later
       end
     end
   end
+
+  def test_assert_performed_job_with_at_option
+    assert_performed_with(job: HelloJob, at: Date.tomorrow.noon) do
+      HelloJob.set(wait_until: Date.tomorrow.noon).perform_later
+    end
+
+    assert_raise ActiveSupport::TestCase::Assertion do
+      assert_performed_with(job: HelloJob, at: Date.today.noon) do
+        HelloJob.set(wait_until: Date.tomorrow.noon).perform_later
+      end
+    end
+  end
+
+  def test_assert_performed_job_with_global_id_args
+    ricardo = Person.new(9)
+    assert_performed_with(job: HelloJob, args: [ricardo]) do
+      HelloJob.perform_later(ricardo)
+    end
+  end
+
+  def test_assert_performed_job_failure_with_global_id_args
+    ricardo = Person.new(9)
+    wilma = Person.new(11)
+    error = assert_raise ActiveSupport::TestCase::Assertion do
+      assert_performed_with(job: HelloJob, args: [wilma]) do
+        HelloJob.perform_later(ricardo)
+      end
+    end
+
+    assert_equal "No performed job found with {:job=>HelloJob, :args=>[#{wilma.inspect}]}", error.message
+  end
+
+  def test_assert_performed_job_does_not_change_jobs_count
+    assert_performed_with(job: HelloJob) do
+      HelloJob.perform_later
+    end
+
+    assert_performed_with(job: HelloJob) do
+      HelloJob.perform_later
+    end
+
+    assert_equal 2, ActiveJob::Base.queue_adapter.performed_jobs.count
+  end
 end
diff --git a/activejob/test/cases/translation_test.rb b/activejob/test/cases/translation_test.rb
new file mode 100644
index 0000000000..d5e3aaf9e3
--- /dev/null
+++ b/activejob/test/cases/translation_test.rb
@@ -0,0 +1,20 @@
+require 'helper'
+require 'jobs/translated_hello_job'
+
+class TranslationTest < ActiveSupport::TestCase
+  setup do
+    JobBuffer.clear
+    I18n.available_locales = [:en, :de]
+    @job = TranslatedHelloJob.new('Johannes')
+  end
+
+  teardown do
+    I18n.available_locales = [:en]
+  end
+
+  test 'it performs the job in the given locale' do
+    @job.locale = :de
+    @job.perform_now
+    assert_equal "Johannes says Guten Tag", JobBuffer.last_value
+  end
+end
diff --git a/activejob/test/helper.rb b/activejob/test/helper.rb
index db5265d7b2..7e86415f48 100644
--- a/activejob/test/helper.rb
+++ b/activejob/test/helper.rb
@@ -3,16 +3,16 @@ require File.expand_path('../../../load_paths', __FILE__)
 require 'active_job'
 require 'support/job_buffer'
 
+ActiveSupport.halt_callback_chains_on_return_false = false
 GlobalID.app = 'aj'
 
-@adapter  = ENV['AJADAPTER'] || 'inline'
+@adapter  = ENV['AJ_ADAPTER'] || 'inline'
 
 if ENV['AJ_INTEGRATION_TESTS']
   require 'support/integration/helper'
 else
+  ActiveJob::Base.logger = Logger.new(nil)
   require "adapters/#{@adapter}"
 end
 
 require 'active_support/testing/autorun'
-
-ActiveSupport::TestCase.test_order = :random
diff --git a/activejob/test/integration/queuing_test.rb b/activejob/test/integration/queuing_test.rb
index 38874b51a8..e435ed4aa6 100644
--- a/activejob/test/integration/queuing_test.rb
+++ b/activejob/test/integration/queuing_test.rb
@@ -1,5 +1,6 @@
 require 'helper'
 require 'jobs/logging_job'
+require 'jobs/hello_job'
 require 'active_support/core_ext/numeric/time'
 
 class QueuingTest < ActiveSupport::TestCase
@@ -10,7 +11,7 @@ class QueuingTest < ActiveSupport::TestCase
   end
 
   test 'should not run jobs queued on a non-listening queue' do
-    skip if adapter_is?(:inline) || adapter_is?(:sucker_punch)
+    skip if adapter_is?(:inline, :async, :sucker_punch, :que)
     old_queue = TestJob.queue_name
 
     begin
@@ -23,6 +24,16 @@ class QueuingTest < ActiveSupport::TestCase
     end
   end
 
+  test 'should supply a wrapped class name to Sidekiq' do
+    skip unless adapter_is?(:sidekiq)
+    Sidekiq::Testing.fake! do
+      ::HelloJob.perform_later
+      hash = ActiveJob::QueueAdapters::SidekiqAdapter::JobWrapper.jobs.first
+      assert_equal "ActiveJob::QueueAdapters::SidekiqAdapter::JobWrapper", hash['class']
+      assert_equal "HelloJob", hash['wrapped']
+    end
+  end
+
   test 'should not run job enqueued in the future' do
     begin
       TestJob.set(wait: 10.minutes).perform_later @id
@@ -35,7 +46,7 @@ class QueuingTest < ActiveSupport::TestCase
 
   test 'should run job enqueued in the future at the specified time' do
     begin
-      TestJob.set(wait: 3.seconds).perform_later @id
+      TestJob.set(wait: 5.seconds).perform_later @id
       wait_for_jobs_to_finish_for(2.seconds)
       assert_not job_executed
       wait_for_jobs_to_finish_for(10.seconds)
@@ -44,4 +55,45 @@ class QueuingTest < ActiveSupport::TestCase
       skip
     end
   end
+
+  test 'should supply a provider_job_id when available for immediate jobs' do
+    skip unless adapter_is?(:delayed_job, :sidekiq, :qu, :que, :queue_classic)
+    test_job = TestJob.perform_later @id
+    assert test_job.provider_job_id, 'Provider job id should be set by provider'
+  end
+
+  test 'should supply a provider_job_id when available for delayed jobs' do
+    skip unless adapter_is?(:delayed_job, :sidekiq, :que, :queue_classic)
+    delayed_test_job = TestJob.set(wait: 1.minute).perform_later @id
+    assert delayed_test_job.provider_job_id, 'Provider job id should by set for delayed jobs by provider'
+  end
+
+  test 'current locale is kept while running perform_later' do
+    skip if adapter_is?(:inline)
+
+    begin
+      I18n.available_locales = [:en, :de]
+      I18n.locale = :de
+
+      TestJob.perform_later @id
+      wait_for_jobs_to_finish_for(5.seconds)
+      assert job_executed
+      assert_equal 'de', job_output
+    ensure
+      I18n.available_locales = [:en]
+      I18n.locale = :en
+    end
+  end
+
+  test 'should run job with higher priority first' do
+    skip unless adapter_is?(:delayed_job, :que)
+
+    wait_until = Time.now + 3.seconds
+    TestJob.set(wait_until: wait_until, priority: 20).perform_later "#{@id}.1"
+    TestJob.set(wait_until: wait_until, priority: 10).perform_later "#{@id}.2"
+    wait_for_jobs_to_finish_for(10.seconds)
+    assert job_executed "#{@id}.1"
+    assert job_executed "#{@id}.2"
+    assert job_executed_at("#{@id}.2") < job_executed_at("#{@id}.1")
+  end
 end
diff --git a/activejob/test/jobs/kwargs_job.rb b/activejob/test/jobs/kwargs_job.rb
new file mode 100644
index 0000000000..2df17d15ae
--- /dev/null
+++ b/activejob/test/jobs/kwargs_job.rb
@@ -0,0 +1,7 @@
+require_relative '../support/job_buffer'
+
+class KwargsJob < ActiveJob::Base
+  def perform(argument: 1)
+    JobBuffer.add("Job with argument: #{argument}")
+  end
+end
diff --git a/activejob/test/jobs/queue_as_job.rb b/activejob/test/jobs/queue_as_job.rb
new file mode 100644
index 0000000000..897aef52e5
--- /dev/null
+++ b/activejob/test/jobs/queue_as_job.rb
@@ -0,0 +1,10 @@
+require_relative '../support/job_buffer'
+
+class QueueAsJob < ActiveJob::Base
+  MY_QUEUE = :low_priority
+  queue_as MY_QUEUE
+
+  def perform(greeter = "David")
+    JobBuffer.add("#{greeter} says hello")
+  end
+end
diff --git a/activejob/test/jobs/translated_hello_job.rb b/activejob/test/jobs/translated_hello_job.rb
new file mode 100644
index 0000000000..9657cd3f54
--- /dev/null
+++ b/activejob/test/jobs/translated_hello_job.rb
@@ -0,0 +1,10 @@
+require_relative '../support/job_buffer'
+
+class TranslatedHelloJob < ActiveJob::Base
+  def perform(greeter = "David")
+    translations = { en: 'Hello', de: 'Guten Tag' }
+    hello        = translations[I18n.locale]
+
+    JobBuffer.add("#{greeter} says #{hello}")
+  end
+end
diff --git a/activejob/test/support/integration/adapters/async.rb b/activejob/test/support/integration/adapters/async.rb
new file mode 100644
index 0000000000..42beb12b1f
--- /dev/null
+++ b/activejob/test/support/integration/adapters/async.rb
@@ -0,0 +1,9 @@
+module AsyncJobsManager
+  def setup
+    ActiveJob::Base.queue_adapter = :async
+  end
+
+  def clear_jobs
+    ActiveJob::AsyncJob::QUEUES.clear
+  end
+end
diff --git a/activejob/test/support/integration/adapters/qu.rb b/activejob/test/support/integration/adapters/qu.rb
index 3a5b66a057..256ddb3cf3 100644
--- a/activejob/test/support/integration/adapters/qu.rb
+++ b/activejob/test/support/integration/adapters/qu.rb
@@ -3,7 +3,7 @@ module QuJobsManager
     require 'qu-rails'
     require 'qu-redis'
     ActiveJob::Base.queue_adapter = :qu
-    ENV['REDISTOGO_URL'] = "tcp://127.0.0.1:6379/12"
+    ENV['REDISTOGO_URL'] = "redis://127.0.0.1:6379/12"
     backend = Qu::Backend::Redis.new
     backend.namespace = "active_jobs_int_test"
     Qu.backend  = backend
diff --git a/activejob/test/support/integration/adapters/que.rb b/activejob/test/support/integration/adapters/que.rb
index ba7657a42a..0cd8952a28 100644
--- a/activejob/test/support/integration/adapters/que.rb
+++ b/activejob/test/support/integration/adapters/que.rb
@@ -2,6 +2,15 @@ module QueJobsManager
   def setup
     require 'sequel'
     ActiveJob::Base.queue_adapter = :que
+    Que.mode = :off
+    Que.worker_count = 1
+  end
+
+  def clear_jobs
+    Que.clear!
+  end
+
+  def start_workers
     que_url = ENV['QUE_DATABASE_URL'] || 'postgres:///active_jobs_que_int_test'
     uri = URI.parse(que_url)
     user = uri.user||ENV['USER']
@@ -11,24 +20,17 @@ module QueJobsManager
     %x{#{"PGPASSWORD=\"#{pass}\"" if pass} psql -c 'create database "#{db}"' -U #{user} -t template1}
     Que.connection = Sequel.connect(que_url)
     Que.migrate!
-    Que.mode = :off
-    Que.worker_count = 1
-  rescue Sequel::DatabaseConnectionError
-    puts "Cannot run integration tests for que. To be able to run integration tests for que you need to install and start postgresql.\n"
-    exit
-  end
-
-  def clear_jobs
-    Que.clear!
-  end
 
-  def start_workers
     @thread = Thread.new do
       loop do
-        Que::Job.work("integration_tests")
+        Que::Job.work
         sleep 0.5
       end
     end
+
+  rescue Sequel::DatabaseConnectionError
+    puts "Cannot run integration tests for que. To be able to run integration tests for que you need to install and start postgresql.\n"
+    exit
   end
 
   def stop_workers
diff --git a/activejob/test/support/integration/adapters/queue_classic.rb b/activejob/test/support/integration/adapters/queue_classic.rb
index 038473ccdc..29c04bf625 100644
--- a/activejob/test/support/integration/adapters/queue_classic.rb
+++ b/activejob/test/support/integration/adapters/queue_classic.rb
@@ -1,18 +1,9 @@
 module QueueClassicJobsManager
   def setup
     ENV['QC_DATABASE_URL'] ||= 'postgres:///active_jobs_qc_int_test'
+    ENV['QC_RAILS_DATABASE'] = 'false'
     ENV['QC_LISTEN_TIME']    = "0.5"
-    uri = URI.parse(ENV['QC_DATABASE_URL'])
-    user = uri.user||ENV['USER']
-    pass = uri.password
-    db   = uri.path[1..-1]
-    %x{#{"PGPASSWORD=\"#{pass}\"" if pass} psql -c 'drop database if exists "#{db}"' -U #{user} -t template1}
-    %x{#{"PGPASSWORD=\"#{pass}\"" if pass} psql -c 'create database "#{db}"' -U #{user} -t template1}
     ActiveJob::Base.queue_adapter = :queue_classic
-    QC::Setup.create
-  rescue PG::ConnectionBad
-    puts "Cannot run integration tests for queue_classic. To be able to run integration tests for queue_classic you need to install and start postgresql.\n"
-    exit
   end
 
   def clear_jobs
@@ -20,11 +11,24 @@ module QueueClassicJobsManager
   end
 
   def start_workers
-    QC::Conn.disconnect
+    uri = URI.parse(ENV['QC_DATABASE_URL'])
+    user = uri.user||ENV['USER']
+    pass = uri.password
+    db   = uri.path[1..-1]
+    %x{#{"PGPASSWORD=\"#{pass}\"" if pass} psql -c 'drop database if exists "#{db}"' -U #{user} -t template1}
+    %x{#{"PGPASSWORD=\"#{pass}\"" if pass} psql -c 'create database "#{db}"' -U #{user} -t template1}
+    QC::Setup.create
+
+    QC.default_conn_adapter.disconnect
+    QC.default_conn_adapter = nil
     @pid = fork do
       worker = QC::Worker.new(q_name: 'integration_tests')
       worker.start
     end
+
+  rescue PG::ConnectionBad
+    puts "Cannot run integration tests for queue_classic. To be able to run integration tests for queue_classic you need to install and start postgresql.\n"
+    exit
   end
 
   def stop_workers
diff --git a/activejob/test/support/integration/adapters/sidekiq.rb b/activejob/test/support/integration/adapters/sidekiq.rb
index 6ff18fb56a..9aa07bcb52 100644
--- a/activejob/test/support/integration/adapters/sidekiq.rb
+++ b/activejob/test/support/integration/adapters/sidekiq.rb
@@ -1,6 +1,8 @@
-require 'sidekiq/cli'
 require 'sidekiq/api'
 
+require 'sidekiq/testing'
+Sidekiq::Testing.disable!
+
 module SidekiqJobsManager
 
   def setup
@@ -17,33 +19,71 @@ module SidekiqJobsManager
   end
 
   def start_workers
-    fork do
-      sidekiq = Sidekiq::CLI.instance
+    continue_read, continue_write = IO.pipe
+    death_read, death_write = IO.pipe
+
+    @pid = fork do
+      continue_read.close
+      death_write.close
+
+      # Celluloid & Sidekiq are not warning-clean :(
+      $VERBOSE = false
+
+      $stdin.reopen('/dev/null')
+      $stdout.sync = true
+      $stderr.sync = true
+
       logfile = Rails.root.join("log/sidekiq.log").to_s
-      pidfile = Rails.root.join("tmp/sidekiq.pid").to_s
-      sidekiq.parse([ "--require", Rails.root.to_s,
-                      "--queue",   "integration_tests",
-                      "--logfile", logfile,
-                      "--pidfile", pidfile,
-                      "--environment", "test",
-                      "--concurrency", "1",
-                      "--timeout", "1",
-                      "--daemon",
-                      ])
+      Sidekiq::Logging.initialize_logger(logfile)
+
+      self_read, self_write = IO.pipe
+      trap "TERM" do
+        self_write.puts("TERM")
+      end
+
+      Thread.new do
+        begin
+          death_read.read
+        rescue Exception
+        end
+        self_write.puts("TERM")
+      end
+
       require 'celluloid'
-      require 'sidekiq/scheduled'
-      Sidekiq.poll_interval = 0.5
-      Sidekiq::Scheduled.const_set :INITIAL_WAIT, 1
-      sidekiq.run
+      Celluloid.logger = nil
+      require 'sidekiq/launcher'
+      sidekiq = Sidekiq::Launcher.new({queues: ["integration_tests"],
+                                       environment: "test",
+                                       concurrency: 1,
+                                       timeout: 1,
+                                      })
+      Sidekiq.average_scheduled_poll_interval = 0.5
+      Sidekiq.options[:poll_interval_average] = 1
+      begin
+        sidekiq.run
+        continue_write.puts "started"
+        while readable_io = IO.select([self_read])
+          signal = readable_io.first[0].gets.strip
+          raise Interrupt if signal == "TERM"
+        end
+      rescue Interrupt
+      end
+
+      sidekiq.stop
+      exit!
     end
-    sleep 1
+    continue_write.close
+    death_read.close
+    @worker_lifeline = death_write
+
+    raise "Failed to start worker" unless continue_read.gets == "started\n"
   end
 
   def stop_workers
-    pidfile = Rails.root.join("tmp/sidekiq.pid").to_s
-    Process.kill 'TERM', File.open(pidfile).read.to_i
-    FileUtils.rm_f pidfile
-  rescue
+    if @pid
+      Process.kill 'TERM', @pid
+      Process.wait @pid
+    end
   end
 
   def can_run?
diff --git a/activejob/test/support/integration/dummy_app_template.rb b/activejob/test/support/integration/dummy_app_template.rb
index 65994d6a1c..0c062a025e 100644
--- a/activejob/test/support/integration/dummy_app_template.rb
+++ b/activejob/test/support/integration/dummy_app_template.rb
@@ -1,20 +1,25 @@
-if ENV['AJADAPTER'] == 'delayed_job'
+if ENV['AJ_ADAPTER'] == 'delayed_job'
   generate "delayed_job:active_record", "--quiet"
-  rake("db:migrate")
 end
 
+rake("db:migrate")
+
 initializer 'activejob.rb', <<-CODE
 require "#{File.expand_path("../jobs_manager.rb",  __FILE__)}"
 JobsManager.current_manager.setup
 CODE
 
+initializer 'i18n.rb', <<-CODE
+I18n.available_locales = [:en, :de]
+CODE
+
 file 'app/jobs/test_job.rb', <<-CODE
 class TestJob < ActiveJob::Base
   queue_as :integration_tests
 
   def perform(x)
     File.open(Rails.root.join("tmp/\#{x}"), "w+") do |f|
-      f.write x
+      f.write I18n.locale
     end
   end
 end
diff --git a/activejob/test/support/integration/helper.rb b/activejob/test/support/integration/helper.rb
index 9bd45e09e8..4a1b0bfbcb 100644
--- a/activejob/test/support/integration/helper.rb
+++ b/activejob/test/support/integration/helper.rb
@@ -1,4 +1,4 @@
-puts "*** rake aj:integration:#{ENV['AJADAPTER']} ***\n"
+puts "\n\n*** rake aj:integration:#{ENV['AJ_ADAPTER']} ***\n"
 
 ENV["RAILS_ENV"] = "test"
 ActiveJob::Base.queue_name_prefix = nil
@@ -20,7 +20,7 @@ require 'rails/test_help'
 Rails.backtrace_cleaner.remove_silencers!
 
 require_relative 'test_case_helpers'
-ActiveSupport::TestCase.send(:include, TestCaseHelpers)
+ActiveSupport::TestCase.include(TestCaseHelpers)
 
 JobsManager.current_manager.start_workers
 
diff --git a/activejob/test/support/integration/jobs_manager.rb b/activejob/test/support/integration/jobs_manager.rb
index 4df34aaeb1..78d48e8d9a 100644
--- a/activejob/test/support/integration/jobs_manager.rb
+++ b/activejob/test/support/integration/jobs_manager.rb
@@ -3,7 +3,7 @@ class JobsManager
   attr :adapter_name
 
   def self.current_manager
-    @@managers[ENV['AJADAPTER']] ||= new(ENV['AJADAPTER'])
+    @@managers[ENV['AJ_ADAPTER']] ||= new(ENV['AJ_ADAPTER'])
   end
 
   def initialize(adapter_name)
diff --git a/activejob/test/support/integration/test_case_helpers.rb b/activejob/test/support/integration/test_case_helpers.rb
index ee2f6aebea..8319d09520 100644
--- a/activejob/test/support/integration/test_case_helpers.rb
+++ b/activejob/test/support/integration/test_case_helpers.rb
@@ -5,7 +5,7 @@ module TestCaseHelpers
   extend ActiveSupport::Concern
 
   included do
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     setup do
       clear_jobs
@@ -27,8 +27,8 @@ module TestCaseHelpers
       jobs_manager.clear_jobs
     end
 
-    def adapter_is?(adapter)
-      ActiveJob::Base.queue_adapter.name.split("::").last.gsub(/Adapter$/, '').underscore==adapter.to_s
+    def adapter_is?(*adapter_class_symbols)
+      adapter_class_symbols.map(&:to_s).include?(ActiveJob::Base.queue_adapter.class.name.split("::").last.gsub(/Adapter$/, '').underscore)
     end
 
     def wait_for_jobs_to_finish_for(seconds=60)
@@ -42,7 +42,15 @@ module TestCaseHelpers
       end
     end
 
-    def job_executed
-      Dummy::Application.root.join("tmp/#{@id}").exist?
+    def job_executed(id=@id)
+      Dummy::Application.root.join("tmp/#{id}").exist?
+    end
+
+    def job_executed_at(id=@id)
+      File.new(Dummy::Application.root.join("tmp/#{id}")).ctime
+    end
+
+    def job_output
+      File.read Dummy::Application.root.join("tmp/#{@id}")
     end
 end
diff --git a/activejob/test/support/que/inline.rb b/activejob/test/support/que/inline.rb
index 2e210acb6b..0950e52d28 100644
--- a/activejob/test/support/que/inline.rb
+++ b/activejob/test/support/que/inline.rb
@@ -3,7 +3,12 @@ require 'que'
 Que::Job.class_eval do
   class << self; alias_method :original_enqueue, :enqueue; end
   def self.enqueue(*args)
-    args.pop if args.last.is_a?(Hash)
+    if args.last.is_a?(Hash)
+      options = args.pop
+      options.delete(:run_at)
+      options.delete(:priority)
+      args << options unless options.empty?
+    end
     self.run(*args)
   end
 end
diff --git a/activemodel/CHANGELOG.md b/activemodel/CHANGELOG.md
index fb4b972282..a3368cd197 100644
--- a/activemodel/CHANGELOG.md
+++ b/activemodel/CHANGELOG.md
@@ -1,7 +1,113 @@
+*   Validate multiple contexts on `valid?` and `invalid?` at once.
+
+    Example:
+
+        class Person
+          include ActiveModel::Validations
+
+          attr_reader :name, :title
+          validates_presence_of :name, on: :create
+          validates_presence_of :title, on: :update
+        end
+
+        person = Person.new
+        person.valid?([:create, :update])    # => false
+        person.errors.messages               # => {:name=>["can't be blank"], :title=>["can't be blank"]}
+
+    *Dmitry Polushkin*
+
+*   Add case_sensitive option for confirmation validator in models.
+
+    *Akshat Sharma*
+
+*   Ensure `method_missing` is called for methods passed to
+    `ActiveModel::Serialization#serializable_hash` that don't exist.
+
+    *Jay Elaraj*
+
+*   Remove `ActiveModel::Serializers::Xml` from core.
+
+    *Zachary Scott*
+
+*   Add `ActiveModel::Dirty#[attr_name]_previously_changed?` and
+    `ActiveModel::Dirty#[attr_name]_previous_change` to improve access
+    to recorded changes after the model has been saved.
+
+    It makes the dirty-attributes query methods consistent before and after
+    saving.
+
+    *Fernando Tapia Rico*
+
+*   Deprecate the `:tokenizer` option for `validates_length_of`, in favor of
+    plain Ruby.
+
+    *Sean Griffin*
+
+*   Deprecate `ActiveModel::Errors#add_on_empty` and `ActiveModel::Errors#add_on_blank`
+    with no replacement.
+
+    *Wojciech Wnętrzak*
+
+*   Deprecate `ActiveModel::Errors#get`, `ActiveModel::Errors#set` and
+    `ActiveModel::Errors#[]=` methods that have inconsistent behavior.
+
+    *Wojciech Wnętrzak*
+
+*   Allow symbol as values for `tokenize` of `LengthValidator`.
+
+    *Kensuke Naito*
+
+*   Assigning an unknown attribute key to an `ActiveModel` instance during initialization
+    will now raise `ActiveModel::AttributeAssignment::UnknownAttributeError` instead of
+    `NoMethodError`.
+
+    Example:
+
+        User.new(foo: 'some value')
+        # => ActiveModel::AttributeAssignment::UnknownAttributeError: unknown attribute 'foo' for User.
+
+    *Eugene Gilburg*
+
+*   Extracted `ActiveRecord::AttributeAssignment` to `ActiveModel::AttributeAssignment`
+    allowing to use it for any object as an includable module.
+
+    Example:
+
+        class Cat
+          include ActiveModel::AttributeAssignment
+          attr_accessor :name, :status
+        end
+
+        cat = Cat.new
+        cat.assign_attributes(name: "Gorby", status: "yawning")
+        cat.name   # => 'Gorby'
+        cat.status # => 'yawning'
+        cat.assign_attributes(status: "sleeping")
+        cat.name   # => 'Gorby'
+        cat.status # => 'sleeping'
+
+    *Bogdan Gusiev*
+
+*   Add `ActiveModel::Errors#details`
+
+    To be able to return type of used validator, one can now call `details`
+    on errors instance.
+
+    Example:
+
+        class User < ActiveRecord::Base
+          validates :name, presence: true
+        end
+
+        user = User.new; user.valid?; user.errors.details
+        => {name: [{error: :blank}]}
+
+    *Wojciech Wnętrzak*
+
 *   Change validates_acceptance_of to accept true by default.
 
     The default for validates_acceptance_of is now "1" and true.
-    In the past, only "1" was the default and you were required to add 
+    In the past, only "1" was the default and you were required to add
     accept: true.
 
 *   Remove deprecated `ActiveModel::Dirty#reset_#{attribute}` and
@@ -13,10 +119,10 @@
 
     The preferred method to halt a callback chain from now on is to explicitly
     `throw(:abort)`.
-    In the past, returning `false` in an ActiveModel or ActiveModel::Validations
-    `before_` callback had the side effect of halting the callback chain.
+    In the past, returning `false` in an Active Model `before_` callback had
+    the side effect of halting the callback chain.
     This is not recommended anymore and, depending on the value of the
-    `config.active_support.halt_callback_chains_on_return_false` option, will
+    `ActiveSupport.halt_callback_chains_on_return_false` option, will
     either not work at all or display a deprecation warning.
 
 
diff --git a/activemodel/README.rdoc b/activemodel/README.rdoc
index f6beff14e1..20414c1d61 100644
--- a/activemodel/README.rdoc
+++ b/activemodel/README.rdoc
@@ -49,7 +49,7 @@ behavior out of the box:
         send("#{attr}=", nil)
       end
     end
-  
+
     person = Person.new
     person.clear_name
     person.clear_age
@@ -132,7 +132,7 @@ behavior out of the box:
         "Name"
       end
     end
-  
+
     person = Person.new
     person.name = nil
     person.validate!
@@ -154,8 +154,8 @@ behavior out of the box:
 
 * Making objects serializable
 
-  ActiveModel::Serialization provides a standard interface for your object
-  to provide +to_json+ or +to_xml+ serialization.
+  <tt>ActiveModel::Serialization</tt> provides a standard interface for your object
+  to provide +to_json+ serialization.
 
     class SerialPerson
       include ActiveModel::Serialization
@@ -177,13 +177,6 @@ behavior out of the box:
     s = SerialPerson.new
     s.to_json             # => "{\"name\":null}"
 
-    class SerialPerson
-      include ActiveModel::Serializers::Xml
-    end
-
-    s = SerialPerson.new
-    s.to_xml              # => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<serial-person...
-
   {Learn more}[link:classes/ActiveModel/Serialization.html]
 
 * Internationalization (i18n) support
@@ -216,10 +209,10 @@ behavior out of the box:
   {Learn more}[link:classes/ActiveModel/Validations.html]
 
 * Custom validators
-  
+
     class HasNameValidator < ActiveModel::Validator
       def validate(record)
-        record.errors[:name] = "must exist" if record.name.blank?
+        record.errors.add(:name, "must exist") if record.name.blank?
       end
     end
 
@@ -242,7 +235,7 @@ behavior out of the box:
 
 The latest version of Active Model can be installed with RubyGems:
 
-  % [sudo] gem install activemodel
+  % gem install activemodel
 
 Source code can be downloaded as part of the Rails project on GitHub
 
diff --git a/activemodel/Rakefile b/activemodel/Rakefile
index c30a559ef5..5a67f0a151 100644
--- a/activemodel/Rakefile
+++ b/activemodel/Rakefile
@@ -1,12 +1,12 @@
-dir = File.dirname(__FILE__)
-
 require 'rake/testtask'
 
+dir = File.dirname(__FILE__)
+
 task :default => :test
 
 Rake::TestTask.new do |t|
   t.libs << "test"
-  t.test_files = Dir.glob("#{dir}/test/cases/**/*_test.rb").sort
+  t.test_files = Dir.glob("#{dir}/test/cases/**/*_test.rb")
   t.warning = true
   t.verbose = true
   t.ruby_opts = ["--dev"] if defined?(JRUBY_VERSION)
@@ -19,18 +19,3 @@ namespace :test do
     end or raise "Failures"
   end
 end
-
-require 'rubygems/package_task'
-
-spec = eval(File.read("#{dir}/activemodel.gemspec"))
-
-Gem::PackageTask.new(spec) do |p|
-  p.gem_spec = spec
-end
-
-desc "Release to rubygems"
-task :release => :package do
-  require 'rake/gemcutter'
-  Rake::Gemcutter::Tasks.new(spec).define
-  Rake::Task['gem:push'].invoke
-end
diff --git a/activemodel/activemodel.gemspec b/activemodel/activemodel.gemspec
index 3c6eb56296..8d00b3aa27 100644
--- a/activemodel/activemodel.gemspec
+++ b/activemodel/activemodel.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'A toolkit for building modeling frameworks (part of Rails).'
   s.description = 'A toolkit for building modeling frameworks like Active Record. Rich support for attributes, callbacks, validations, serialization, internationalization, and testing.'
 
-  s.required_ruby_version = '>= 2.2.0'
+  s.required_ruby_version = '>= 2.2.2'
 
   s.license = 'MIT'
 
diff --git a/activemodel/bin/test b/activemodel/bin/test
new file mode 100755
index 0000000000..404cabba51
--- /dev/null
+++ b/activemodel/bin/test
@@ -0,0 +1,4 @@
+#!/usr/bin/env ruby
+COMPONENT_ROOT = File.expand_path("../../", __FILE__)
+require File.expand_path("../tools/test", COMPONENT_ROOT)
+exit Minitest.run(ARGV)
diff --git a/activemodel/lib/active_model.rb b/activemodel/lib/active_model.rb
index 46d60db756..4e1b3f7495 100644
--- a/activemodel/lib/active_model.rb
+++ b/activemodel/lib/active_model.rb
@@ -28,6 +28,7 @@ require 'active_model/version'
 module ActiveModel
   extend ActiveSupport::Autoload
 
+  autoload :AttributeAssignment
   autoload :AttributeMethods
   autoload :BlockValidator, 'active_model/validator'
   autoload :Callbacks
@@ -49,6 +50,7 @@ module ActiveModel
   eager_autoload do
     autoload :Errors
     autoload :StrictValidationFailed, 'active_model/errors'
+    autoload :UnknownAttributeError, 'active_model/errors'
   end
 
   module Serializers
@@ -56,7 +58,6 @@ module ActiveModel
 
     eager_autoload do
       autoload :JSON
-      autoload :Xml
     end
   end
 
diff --git a/activemodel/lib/active_model/attribute_assignment.rb b/activemodel/lib/active_model/attribute_assignment.rb
new file mode 100644
index 0000000000..087d11f708
--- /dev/null
+++ b/activemodel/lib/active_model/attribute_assignment.rb
@@ -0,0 +1,52 @@
+require 'active_support/core_ext/hash/keys'
+
+module ActiveModel
+  module AttributeAssignment
+    include ActiveModel::ForbiddenAttributesProtection
+
+    # Allows you to set all the attributes by passing in a hash of attributes with
+    # keys matching the attribute names.
+    #
+    # If the passed hash responds to <tt>permitted?</tt> method and the return value
+    # of this method is +false+ an <tt>ActiveModel::ForbiddenAttributesError</tt>
+    # exception is raised.
+    #
+    #   class Cat
+    #     include ActiveModel::AttributeAssignment
+    #     attr_accessor :name, :status
+    #   end
+    #
+    #   cat = Cat.new
+    #   cat.assign_attributes(name: "Gorby", status: "yawning")
+    #   cat.name # => 'Gorby'
+    #   cat.status => 'yawning'
+    #   cat.assign_attributes(status: "sleeping")
+    #   cat.name # => 'Gorby'
+    #   cat.status => 'sleeping'
+    def assign_attributes(new_attributes)
+      if !new_attributes.respond_to?(:stringify_keys)
+        raise ArgumentError, "When assigning attributes, you must pass a hash as an argument."
+      end
+      return if new_attributes.blank?
+
+      attributes = new_attributes.stringify_keys
+      _assign_attributes(sanitize_for_mass_assignment(attributes))
+    end
+
+    private
+
+    def _assign_attributes(attributes)
+      attributes.each do |k, v|
+        _assign_attribute(k, v)
+      end
+    end
+
+    def _assign_attribute(k, v)
+      if respond_to?("#{k}=")
+        public_send("#{k}=", v)
+      else
+        raise UnknownAttributeError.new(self, k)
+      end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/attribute_methods.rb b/activemodel/lib/active_model/attribute_methods.rb
index 96be551264..1963a3fc4e 100644
--- a/activemodel/lib/active_model/attribute_methods.rb
+++ b/activemodel/lib/active_model/attribute_methods.rb
@@ -1,4 +1,4 @@
-require 'thread_safe'
+require 'concurrent'
 require 'mutex_m'
 
 module ActiveModel
@@ -23,7 +23,7 @@ module ActiveModel
   # The requirements to implement <tt>ActiveModel::AttributeMethods</tt> are to:
   #
   # * <tt>include ActiveModel::AttributeMethods</tt> in your class.
-  # * Call each of its method you want to add, such as +attribute_method_suffix+
+  # * Call each of its methods you want to add, such as +attribute_method_suffix+
   #   or +attribute_method_prefix+.
   # * Call +define_attribute_methods+ after the other methods are called.
   # * Define the various generic +_attribute+ methods that you have declared.
@@ -225,9 +225,9 @@ module ActiveModel
       end
 
       # Declares the attributes that should be prefixed and suffixed by
-      # ActiveModel::AttributeMethods.
+      # <tt>ActiveModel::AttributeMethods</tt>.
       #
-      # To use, pass attribute names (as strings or symbols), be sure to declare
+      # To use, pass attribute names (as strings or symbols). Be sure to declare
       # +define_attribute_methods+ after you define any prefix, suffix or affix
       # methods, or they will not hook in.
       #
@@ -239,7 +239,7 @@ module ActiveModel
       #
       #     # Call to define_attribute_methods must appear after the
       #     # attribute_method_prefix, attribute_method_suffix or
-      #     # attribute_method_affix declares.
+      #     # attribute_method_affix declarations.
       #     define_attribute_methods :name, :age, :address
       #
       #     private
@@ -253,9 +253,9 @@ module ActiveModel
       end
 
       # Declares an attribute that should be prefixed and suffixed by
-      # ActiveModel::AttributeMethods.
+      # <tt>ActiveModel::AttributeMethods</tt>.
       #
-      # To use, pass an attribute name (as string or symbol), be sure to declare
+      # To use, pass an attribute name (as string or symbol). Be sure to declare
       # +define_attribute_method+ after you define any prefix, suffix or affix
       # method, or they will not hook in.
       #
@@ -267,7 +267,7 @@ module ActiveModel
       #
       #     # Call to define_attribute_method must appear after the
       #     # attribute_method_prefix, attribute_method_suffix or
-      #     # attribute_method_affix declares.
+      #     # attribute_method_affix declarations.
       #     define_attribute_method :name
       #
       #     private
@@ -342,7 +342,7 @@ module ActiveModel
       private
         # The methods +method_missing+ and +respond_to?+ of this module are
         # invoked often in a typical rails, both of which invoke the method
-        # +match_attribute_method?+. The latter method iterates through an
+        # +matched_attribute_method+. The latter method iterates through an
         # array doing regular expression matches, which results in a lot of
         # object creations. Most of the time it returns a +nil+ match. As the
         # match result is always the same given a +method_name+, this cache is
@@ -350,7 +350,7 @@ module ActiveModel
         # significantly (in our case our test suite finishes 10% faster with
         # this cache).
         def attribute_method_matchers_cache #:nodoc:
-          @attribute_method_matchers_cache ||= ThreadSafe::Cache.new(initial_capacity: 4)
+          @attribute_method_matchers_cache ||= Concurrent::Map.new(initial_capacity: 4)
         end
 
         def attribute_method_matchers_matching(method_name) #:nodoc:
@@ -363,7 +363,7 @@ module ActiveModel
         end
 
         # Define a method `name` in `mod` that dispatches to `send`
-        # using the given `extra` args. This fallbacks `define_method`
+        # using the given `extra` args. This falls back on `define_method`
         # and `send` if the given names cannot be compiled.
         def define_proxy_call(include_private, mod, name, send, *extra) #:nodoc:
           defn = if name =~ NAME_COMPILABLE_REGEXP
@@ -372,7 +372,7 @@ module ActiveModel
             "define_method(:'#{name}') do |*args|"
           end
 
-          extra = (extra.map!(&:inspect) << "*args").join(", ")
+          extra = (extra.map!(&:inspect) << "*args").join(", ".freeze)
 
           target = if send =~ CALL_COMPILABLE_REGEXP
             "#{"self." unless include_private}#{send}(#{extra})"
@@ -419,7 +419,7 @@ module ActiveModel
     # returned by <tt>attributes</tt>, as though they were first-class
     # methods. So a +Person+ class with a +name+ attribute can for example use
     # <tt>Person#name</tt> and <tt>Person#name=</tt> and never directly use
-    # the attributes hash -- except for multiple assigns with
+    # the attributes hash -- except for multiple assignments with
     # <tt>ActiveRecord::Base#attributes=</tt>.
     #
     # It's also possible to instantiate related objects, so a <tt>Client</tt>
@@ -429,7 +429,7 @@ module ActiveModel
       if respond_to_without_attributes?(method, true)
         super
       else
-        match = match_attribute_method?(method.to_s)
+        match = matched_attribute_method(method.to_s)
         match ? attribute_missing(match, *args, &block) : super
       end
     end
@@ -454,7 +454,7 @@ module ActiveModel
         # but found among all methods. Which means that the given method is private.
         false
       else
-        !match_attribute_method?(method.to_s).nil?
+        !matched_attribute_method(method.to_s).nil?
       end
     end
 
@@ -466,7 +466,7 @@ module ActiveModel
     private
       # Returns a struct representing the matching attribute method.
       # The struct's attributes are prefix, base and suffix.
-      def match_attribute_method?(method_name)
+      def matched_attribute_method(method_name)
         matches = self.class.send(:attribute_method_matchers_matching, method_name)
         matches.detect { |match| attribute_method?(match.attr_name) }
       end
diff --git a/activemodel/lib/active_model/callbacks.rb b/activemodel/lib/active_model/callbacks.rb
index 6214802074..0d6a3dc52d 100644
--- a/activemodel/lib/active_model/callbacks.rb
+++ b/activemodel/lib/active_model/callbacks.rb
@@ -49,7 +49,7 @@ module ActiveModel
   #    puts 'block successfully called.'
   #  end
   #
-  # You can choose not to have all three callbacks by passing a hash to the
+  # You can choose to have only specific callbacks by passing a hash to the
   # +define_model_callbacks+ method.
   #
   #   define_model_callbacks :create, only: [:after, :before]
@@ -103,6 +103,7 @@ module ActiveModel
     def define_model_callbacks(*callbacks)
       options = callbacks.extract_options!
       options = {
+        terminator: deprecated_false_terminator,
         skip_after_callbacks_if_terminated: true,
         scope: [:kind, :name],
         only: [:before, :around, :after]
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index afba9bab0d..0ab8df42f5 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -52,10 +52,10 @@ module ActiveModel
   #     end
   #   end
   #
-  # A newly instantiated object is unchanged:
+  # A newly instantiated +Person+ object is unchanged:
   #
-  #   person = Person.find_by(name: 'Uncle Bob')
-  #   person.changed?       # => false
+  #   person = Person.new
+  #   person.changed? # => false
   #
   # Change the name:
   #
@@ -71,54 +71,57 @@ module ActiveModel
   # Save the changes:
   #
   #   person.save
-  #   person.changed?       # => false
-  #   person.name_changed?  # => false
+  #   person.changed?      # => false
+  #   person.name_changed? # => false
   #
   # Reset the changes:
   #
-  #   person.previous_changes # => {"name" => ["Uncle Bob", "Bill"]}
+  #   person.previous_changes         # => {"name" => ["Uncle Bob", "Bill"]}
+  #   person.name_previously_changed? # => true
+  #   person.name_previous_change     # => ["Uncle Bob", "Bill"]
   #   person.reload!
-  #   person.previous_changes # => {}
+  #   person.previous_changes         # => {}
   #
   # Rollback the changes:
   #
   #   person.name = "Uncle Bob"
   #   person.rollback!
-  #   person.name           # => "Bill"
-  #   person.name_changed?  # => false
+  #   person.name          # => "Bill"
+  #   person.name_changed? # => false
   #
   # Assigning the same value leaves the attribute unchanged:
   #
   #   person.name = 'Bill'
-  #   person.name_changed?  # => false
-  #   person.name_change    # => nil
+  #   person.name_changed? # => false
+  #   person.name_change   # => nil
   #
   # Which attributes have changed?
   #
   #   person.name = 'Bob'
-  #   person.changed        # => ["name"]
-  #   person.changes        # => {"name" => ["Bill", "Bob"]}
+  #   person.changed # => ["name"]
+  #   person.changes # => {"name" => ["Bill", "Bob"]}
   #
   # If an attribute is modified in-place then make use of
-  # +[attribute_name]_will_change!+ to mark that the attribute is changing.
+  # <tt>[attribute_name]_will_change!</tt> to mark that the attribute is changing.
   # Otherwise \Active \Model can't track changes to in-place attributes. Note
   # that Active Record can detect in-place modifications automatically. You do
-  # not need to call +[attribute_name]_will_change!+ on Active Record models.
+  # not need to call <tt>[attribute_name]_will_change!</tt> on Active Record models.
   #
   #   person.name_will_change!
-  #   person.name_change    # => ["Bill", "Bill"]
+  #   person.name_change # => ["Bill", "Bill"]
   #   person.name << 'y'
-  #   person.name_change    # => ["Bill", "Billy"]
+  #   person.name_change # => ["Bill", "Billy"]
   module Dirty
     extend ActiveSupport::Concern
     include ActiveModel::AttributeMethods
 
     included do
       attribute_method_suffix '_changed?', '_change', '_will_change!', '_was'
+      attribute_method_suffix '_previously_changed?', '_previous_change'
       attribute_method_affix prefix: 'restore_', suffix: '!'
     end
 
-    # Returns +true+ if any attribute have unsaved changes, +false+ otherwise.
+    # Returns +true+ if any of the attributes have unsaved changes, +false+ otherwise.
     #
     #   person.changed? # => false
     #   person.name = 'bob'
@@ -166,7 +169,7 @@ module ActiveModel
       @changed_attributes ||= ActiveSupport::HashWithIndifferentAccess.new
     end
 
-    # Handle <tt>*_changed?</tt> for +method_missing+.
+    # Handles <tt>*_changed?</tt> for +method_missing+.
     def attribute_changed?(attr, options = {}) #:nodoc:
       result = changes_include?(attr)
       result &&= options[:to] == __send__(attr) if options.key?(:to)
@@ -174,11 +177,16 @@ module ActiveModel
       result
     end
 
-    # Handle <tt>*_was</tt> for +method_missing+.
+    # Handles <tt>*_was</tt> for +method_missing+.
     def attribute_was(attr) # :nodoc:
       attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
     end
 
+    # Handles <tt>*_previously_changed?</tt> for +method_missing+.
+    def attribute_previously_changed?(attr, options = {}) #:nodoc:
+      previous_changes_include?(attr)
+    end
+
     # Restore all previous data of the provided attributes.
     def restore_attributes(attributes = changed)
       attributes.each { |attr| restore_attribute! attr }
@@ -186,9 +194,17 @@ module ActiveModel
 
     private
 
+      # Returns +true+ if attr_name is changed, +false+ otherwise.
       def changes_include?(attr_name)
         attributes_changed_by_setter.include?(attr_name)
       end
+      alias attribute_changed_by_setter? changes_include?
+
+      # Returns +true+ if attr_name were changed before the model was saved,
+      # +false+ otherwise.
+      def previous_changes_include?(attr_name)
+        previous_changes.include?(attr_name)
+      end
 
       # Removes current changes and makes them accessible through +previous_changes+.
       def changes_applied # :doc:
@@ -196,18 +212,23 @@ module ActiveModel
         @changed_attributes = ActiveSupport::HashWithIndifferentAccess.new
       end
 
-      # Clear all dirty data: current changes and previous changes.
+      # Clears all dirty data: current changes and previous changes.
       def clear_changes_information # :doc:
         @previously_changed = ActiveSupport::HashWithIndifferentAccess.new
         @changed_attributes = ActiveSupport::HashWithIndifferentAccess.new
       end
 
-      # Handle <tt>*_change</tt> for +method_missing+.
+      # Handles <tt>*_change</tt> for +method_missing+.
       def attribute_change(attr)
         [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
       end
 
-      # Handle <tt>*_will_change!</tt> for +method_missing+.
+      # Handles <tt>*_previous_change</tt> for +method_missing+.
+      def attribute_previous_change(attr)
+        previous_changes[attr] if attribute_previously_changed?(attr)
+      end
+
+      # Handles <tt>*_will_change!</tt> for +method_missing+.
       def attribute_will_change!(attr)
         return if attribute_changed?(attr)
 
@@ -220,7 +241,7 @@ module ActiveModel
         set_attribute_was(attr, value)
       end
 
-      # Handle <tt>restore_*!</tt> for +method_missing+.
+      # Handles <tt>restore_*!</tt> for +method_missing+.
       def restore_attribute!(attr)
         if attribute_changed?(attr)
           __send__("#{attr}=", changed_attributes[attr])
@@ -229,7 +250,7 @@ module ActiveModel
       end
 
       # This is necessary because `changed_attributes` might be overridden in
-      # other implemntations (e.g. in `ActiveRecord`)
+      # other implementations (e.g. in `ActiveRecord`)
       alias_method :attributes_changed_by_setter, :changed_attributes # :nodoc:
 
       # Force an attribute to have a particular "before" value
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index 477edbd120..4726a68f69 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -1,7 +1,7 @@
-# -*- coding: utf-8 -*-
-
 require 'active_support/core_ext/array/conversions'
 require 'active_support/core_ext/string/inflections'
+require 'active_support/core_ext/object/deep_dup'
+require 'active_support/core_ext/string/filters'
 
 module ActiveModel
   # == Active \Model \Errors
@@ -23,7 +23,7 @@ module ActiveModel
   #     attr_reader   :errors
   #
   #     def validate!
-  #       errors.add(:name, "cannot be nil") if name.nil?
+  #       errors.add(:name, :blank, message: "cannot be nil") if name.nil?
   #     end
   #
   #     # The following methods are needed to be minimally implemented
@@ -32,20 +32,20 @@ module ActiveModel
   #       send(attr)
   #     end
   #
-  #     def Person.human_attribute_name(attr, options = {})
+  #     def self.human_attribute_name(attr, options = {})
   #       attr
   #     end
   #
-  #     def Person.lookup_ancestors
+  #     def self.lookup_ancestors
   #       [self]
   #     end
   #   end
   #
-  # The last three methods are required in your object for Errors to be
+  # The last three methods are required in your object for +Errors+ to be
   # able to generate error messages correctly and also handle multiple
-  # languages. Of course, if you extend your object with ActiveModel::Translation
+  # languages. Of course, if you extend your object with <tt>ActiveModel::Translation</tt>
   # you will not need to implement the last two. Likewise, using
-  # ActiveModel::Validations will handle the validation related methods
+  # <tt>ActiveModel::Validations</tt> will handle the validation related methods
   # for you.
   #
   # The above allows you to do:
@@ -58,8 +58,9 @@ module ActiveModel
     include Enumerable
 
     CALLBACKS_OPTIONS = [:if, :unless, :on, :allow_nil, :allow_blank, :strict]
+    MESSAGE_OPTIONS = [:message]
 
-    attr_reader :messages
+    attr_reader :messages, :details
 
     # Pass in the instance of the object that is using the errors object.
     #
@@ -70,11 +71,13 @@ module ActiveModel
     #   end
     def initialize(base)
       @base     = base
-      @messages = {}
+      @messages = Hash.new { |messages, attribute| messages[attribute] = [] }
+      @details  = Hash.new { |details, attribute| details[attribute] = [] }
     end
 
     def initialize_dup(other) # :nodoc:
       @messages = other.messages.dup
+      @details  = other.details.deep_dup
       super
     end
 
@@ -85,6 +88,7 @@ module ActiveModel
     #   person.errors.full_messages # => []
     def clear
       messages.clear
+      details.clear
     end
 
     # Returns +true+ if the error messages include an error for the given key
@@ -96,35 +100,46 @@ module ActiveModel
     def include?(attribute)
       messages[attribute].present?
     end
-    # aliases include?
     alias :has_key? :include?
-    # aliases include?
     alias :key? :include?
 
     # Get messages for +key+.
     #
     #   person.errors.messages   # => {:name=>["cannot be nil"]}
     #   person.errors.get(:name) # => ["cannot be nil"]
-    #   person.errors.get(:age)  # => nil
+    #   person.errors.get(:age)  # => []
     def get(key)
+      ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+        ActiveModel::Errors#get is deprecated and will be removed in Rails 5.1.
+
+        To achieve the same use model.errors[:#{key}].
+      MESSAGE
+
       messages[key]
     end
 
     # Set messages for +key+ to +value+.
     #
-    #   person.errors.get(:name) # => ["cannot be nil"]
+    #   person.errors[:name] # => ["cannot be nil"]
     #   person.errors.set(:name, ["can't be nil"])
-    #   person.errors.get(:name) # => ["can't be nil"]
+    #   person.errors[:name] # => ["can't be nil"]
     def set(key, value)
+      ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+        ActiveModel::Errors#set is deprecated and will be removed in Rails 5.1.
+
+        Use model.errors.add(:#{key}, #{value.inspect}) instead.
+      MESSAGE
+
       messages[key] = value
     end
 
     # Delete messages for +key+. Returns the deleted messages.
     #
-    #   person.errors.get(:name)    # => ["cannot be nil"]
+    #   person.errors[:name]    # => ["cannot be nil"]
     #   person.errors.delete(:name) # => ["cannot be nil"]
-    #   person.errors.get(:name)    # => nil
+    #   person.errors[:name]    # => []
     def delete(key)
+      details.delete(key)
       messages.delete(key)
     end
 
@@ -134,7 +149,7 @@ module ActiveModel
     #   person.errors[:name]  # => ["cannot be nil"]
     #   person.errors['name'] # => ["cannot be nil"]
     def [](attribute)
-      get(attribute.to_sym) || set(attribute.to_sym, [])
+      messages[attribute.to_sym]
     end
 
     # Adds to the supplied attribute the supplied error message.
@@ -142,38 +157,45 @@ module ActiveModel
     #   person.errors[:name] = "must be set"
     #   person.errors[:name] # => ['must be set']
     def []=(attribute, error)
-      self[attribute] << error
+      ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+        ActiveModel::Errors#[]= is deprecated and will be removed in Rails 5.1.
+
+        Use model.errors.add(:#{attribute}, #{error.inspect}) instead.
+      MESSAGE
+
+      messages[attribute.to_sym] << error
     end
 
     # Iterates through each error key, value pair in the error messages hash.
     # Yields the attribute and the error for that attribute. If the attribute
     # has more than one error message, yields once for each error message.
     #
-    #   person.errors.add(:name, "can't be blank")
+    #   person.errors.add(:name, :blank, message: "can't be blank")
     #   person.errors.each do |attribute, error|
     #     # Will yield :name and "can't be blank"
     #   end
     #
-    #   person.errors.add(:name, "must be specified")
+    #   person.errors.add(:name, :not_specified, message: "must be specified")
     #   person.errors.each do |attribute, error|
     #     # Will yield :name and "can't be blank"
     #     # then yield :name and "must be specified"
     #   end
     def each
       messages.each_key do |attribute|
-        self[attribute].each { |error| yield attribute, error }
+        messages[attribute].each { |error| yield attribute, error }
       end
     end
 
     # Returns the number of error messages.
     #
-    #   person.errors.add(:name, "can't be blank")
+    #   person.errors.add(:name, :blank, message: "can't be blank")
     #   person.errors.size # => 1
-    #   person.errors.add(:name, "must be specified")
+    #   person.errors.add(:name, :not_specified, message: "must be specified")
     #   person.errors.size # => 2
     def size
       values.flatten.size
     end
+    alias :count :size
 
     # Returns all message values.
     #
@@ -191,40 +213,20 @@ module ActiveModel
       messages.keys
     end
 
-    # Returns an array of error messages, with the attribute name included.
-    #
-    #   person.errors.add(:name, "can't be blank")
-    #   person.errors.add(:name, "must be specified")
-    #   person.errors.to_a # => ["name can't be blank", "name must be specified"]
-    def to_a
-      full_messages
-    end
-
-    # Returns the number of error messages.
-    #
-    #   person.errors.add(:name, "can't be blank")
-    #   person.errors.count # => 1
-    #   person.errors.add(:name, "must be specified")
-    #   person.errors.count # => 2
-    def count
-      to_a.size
-    end
-
     # Returns +true+ if no errors are found, +false+ otherwise.
     # If the error message is a string it can be empty.
     #
     #   person.errors.full_messages # => ["name cannot be nil"]
     #   person.errors.empty?        # => false
     def empty?
-      all? { |k, v| v && v.empty? && !v.is_a?(String) }
+      size.zero?
     end
-    # aliases empty?
-    alias_method :blank?, :empty?
+    alias :blank? :empty?
 
     # Returns an xml formatted representation of the Errors hash.
     #
-    #   person.errors.add(:name, "can't be blank")
-    #   person.errors.add(:name, "must be specified")
+    #   person.errors.add(:name, :blank, message: "can't be blank")
+    #   person.errors.add(:name, :not_specified, message: "must be specified")
     #   person.errors.to_xml
     #   # =>
     #   #  <?xml version=\"1.0\" encoding=\"UTF-8\"?>
@@ -261,17 +263,20 @@ module ActiveModel
       end
     end
 
-    # Adds +message+ to the error messages on +attribute+. More than one error
-    # can be added to the same +attribute+. If no +message+ is supplied,
-    # <tt>:invalid</tt> is assumed.
+    # Adds +message+ to the error messages and used validator type to +details+ on +attribute+.
+    # More than one error can be added to the same +attribute+.
+    # If no +message+ is supplied, <tt>:invalid</tt> is assumed.
     #
     #   person.errors.add(:name)
     #   # => ["is invalid"]
-    #   person.errors.add(:name, 'must be implemented')
+    #   person.errors.add(:name, :not_implemented, message: "must be implemented")
     #   # => ["is invalid", "must be implemented"]
     #
     #   person.errors.messages
-    #   # => {:name=>["must be implemented", "is invalid"]}
+    #   # => {:name=>["is invalid", "must be implemented"]}
+    #
+    #   person.errors.details
+    #   # => {:name=>[{error: :not_implemented}, {error: :invalid}]}
     #
     # If +message+ is a symbol, it will be translated using the appropriate
     # scope (see +generate_message+).
@@ -293,17 +298,23 @@ module ActiveModel
     # +attribute+ should be set to <tt>:base</tt> if the error is not
     # directly associated with a single attribute.
     #
-    #   person.errors.add(:base, "either name or email must be present")
+    #   person.errors.add(:base, :name_or_email_blank,
+    #     message: "either name or email must be present")
     #   person.errors.messages
     #   # => {:base=>["either name or email must be present"]}
+    #   person.errors.details
+    #   # => {:base=>[{error: :name_or_email_blank}]}
     def add(attribute, message = :invalid, options = {})
+      message = message.call if message.respond_to?(:call)
+      detail  = normalize_detail(attribute, message, options)
       message = normalize_message(attribute, message, options)
       if exception = options[:strict]
         exception = ActiveModel::StrictValidationFailed if exception == true
         raise exception, full_message(attribute, message)
       end
 
-      self[attribute] << message
+      details[attribute.to_sym]  << detail
+      messages[attribute.to_sym] << message
     end
 
     # Will add an error message to each of the attributes in +attributes+
@@ -313,6 +324,14 @@ module ActiveModel
     #   person.errors.messages
     #   # => {:name=>["can't be empty"]}
     def add_on_empty(attributes, options = {})
+      ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+        ActiveModel::Errors#add_on_empty is deprecated and will be removed in Rails 5.1
+
+        To achieve the same use:
+
+          errors.add(attribute, :empty, options) if value.nil? || value.empty?
+      MESSAGE
+
       Array(attributes).each do |attribute|
         value = @base.send(:read_attribute_for_validation, attribute)
         is_empty = value.respond_to?(:empty?) ? value.empty? : false
@@ -327,6 +346,14 @@ module ActiveModel
     #   person.errors.messages
     #   # => {:name=>["can't be blank"]}
     def add_on_blank(attributes, options = {})
+      ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+        ActiveModel::Errors#add_on_blank is deprecated and will be removed in Rails 5.1
+
+        To achieve the same use:
+
+          errors.add(attribute, :empty, options) if value.blank?
+      MESSAGE
+
       Array(attributes).each do |attribute|
         value = @base.send(:read_attribute_for_validation, attribute)
         add(attribute, :blank, options) if value.blank?
@@ -339,6 +366,7 @@ module ActiveModel
     #   person.errors.add :name, :blank
     #   person.errors.added? :name, :blank # => true
     def added?(attribute, message = :invalid, options = {})
+      message = message.call if message.respond_to?(:call)
       message = normalize_message(attribute, message, options)
       self[attribute].include? message
     end
@@ -356,6 +384,7 @@ module ActiveModel
     def full_messages
       map { |attribute, message| full_message(attribute, message) }
     end
+    alias :to_a :full_messages
 
     # Returns all the full error messages for a given attribute in an array.
     #
@@ -368,7 +397,7 @@ module ActiveModel
     #   person.errors.full_messages_for(:name)
     #   # => ["Name is too short (minimum is 5 characters)", "Name can't be blank"]
     def full_messages_for(attribute)
-      (get(attribute) || []).map { |message| full_message(attribute, message) }
+      messages[attribute].map { |message| full_message(attribute, message) }
     end
 
     # Returns a full message for a given attribute.
@@ -421,7 +450,6 @@ module ActiveModel
         defaults = []
       end
 
-      defaults << options.delete(:message)
       defaults << :"#{@base.class.i18n_scope}.errors.messages.#{type}" if @base.class.respond_to?(:i18n_scope)
       defaults << :"errors.attributes.#{attribute}.#{type}"
       defaults << :"errors.messages.#{type}"
@@ -430,6 +458,7 @@ module ActiveModel
       defaults.flatten!
 
       key = defaults.shift
+      defaults = options.delete(:message) if options[:message]
       value = (attribute != :base ? @base.send(:read_attribute_for_validation, attribute) : nil)
 
       options = {
@@ -447,12 +476,14 @@ module ActiveModel
       case message
       when Symbol
         generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS))
-      when Proc
-        message.call
       else
         message
       end
     end
+
+    def normalize_detail(attribute, message, options)
+      { error: message }.merge(options.except(*CALLBACKS_OPTIONS + MESSAGE_OPTIONS))
+    end
   end
 
   # Raised when a validation cannot be corrected by end users and are considered
@@ -472,4 +503,15 @@ module ActiveModel
   #   # => ActiveModel::StrictValidationFailed: Name can't be blank
   class StrictValidationFailed < StandardError
   end
+
+  # Raised when unknown attributes are supplied via mass assignment.
+  class UnknownAttributeError < NoMethodError
+    attr_reader :record, :attribute
+
+    def initialize(record, attribute)
+      @record = record
+      @attribute = attribute
+      super("unknown attribute '#{attribute}' for #{@record.class}.")
+    end
+  end
 end
diff --git a/activemodel/lib/active_model/forbidden_attributes_protection.rb b/activemodel/lib/active_model/forbidden_attributes_protection.rb
index b4fa378601..d2c6a89cc2 100644
--- a/activemodel/lib/active_model/forbidden_attributes_protection.rb
+++ b/activemodel/lib/active_model/forbidden_attributes_protection.rb
@@ -17,8 +17,9 @@ module ActiveModel
   module ForbiddenAttributesProtection # :nodoc:
     protected
       def sanitize_for_mass_assignment(attributes)
-        if attributes.respond_to?(:permitted?) && !attributes.permitted?
-          raise ActiveModel::ForbiddenAttributesError
+        if attributes.respond_to?(:permitted?)
+          raise ActiveModel::ForbiddenAttributesError if !attributes.permitted?
+          attributes.to_h
         else
           attributes
         end
diff --git a/activemodel/lib/active_model/lint.rb b/activemodel/lib/active_model/lint.rb
index 38087521a2..010eaeb170 100644
--- a/activemodel/lib/active_model/lint.rb
+++ b/activemodel/lib/active_model/lint.rb
@@ -21,28 +21,27 @@ module ActiveModel
     # +self+.
     module Tests
 
-      # == Responds to <tt>to_key</tt>
+      # Passes if the object's model responds to <tt>to_key</tt> and if calling
+      # this method returns +nil+ when the object is not persisted.
+      # Fails otherwise.
       #
-      # Returns an Enumerable of all (primary) key attributes
-      # or nil if <tt>model.persisted?</tt> is false. This is used by
-      # <tt>dom_id</tt> to generate unique ids for the object.
+      # <tt>to_key</tt> returns an Enumerable of all (primary) key attributes
+      # of the model, and is used to a generate unique DOM id for the object.
       def test_to_key
         assert model.respond_to?(:to_key), "The model should respond to to_key"
         def model.persisted?() false end
         assert model.to_key.nil?, "to_key should return nil when `persisted?` returns false"
       end
 
-      # == Responds to <tt>to_param</tt>
-      #
-      # Returns a string representing the object's key suitable for use in URLs
-      # or +nil+ if <tt>model.persisted?</tt> is +false+.
+      # Passes if the object's model responds to <tt>to_param</tt> and if
+      # calling this method returns +nil+ when the object is not persisted.
+      # Fails otherwise.
       #
+      # <tt>to_param</tt> is used to represent the object's key in URLs.
       # Implementers can decide to either raise an exception or provide a
       # default in case the record uses a composite primary key. There are no
       # tests for this behavior in lint because it doesn't make sense to force
       # any of the possible implementation strategies on the implementer.
-      # However, if the resource is not persisted?, then <tt>to_param</tt>
-      # should always return +nil+.
       def test_to_param
         assert model.respond_to?(:to_param), "The model should respond to to_param"
         def model.to_key() [1] end
@@ -50,32 +49,34 @@ module ActiveModel
         assert model.to_param.nil?, "to_param should return nil when `persisted?` returns false"
       end
 
-      # == Responds to <tt>to_partial_path</tt>
+      # Passes if the object's model responds to <tt>to_partial_path</tt> and if
+      # calling this method returns a string. Fails otherwise.
       #
-      # Returns a string giving a relative path. This is used for looking up
-      # partials. For example, a BlogPost model might return "blog_posts/blog_post"
+      # <tt>to_partial_path</tt> is used for looking up partials. For example,
+      # a BlogPost model might return "blog_posts/blog_post".
       def test_to_partial_path
         assert model.respond_to?(:to_partial_path), "The model should respond to to_partial_path"
         assert_kind_of String, model.to_partial_path
       end
 
-      # == Responds to <tt>persisted?</tt>
+      # Passes if the object's model responds to <tt>persisted?</tt> and if
+      # calling this method returns either +true+ or +false+. Fails otherwise.
       #
-      # Returns a boolean that specifies whether the object has been persisted
-      # yet. This is used when calculating the URL for an object. If the object
-      # is not persisted, a form for that object, for instance, will route to
-      # the create action. If it is persisted, a form for the object will routes
-      # to the update action.
+      # <tt>persisted?</tt> is used when calculating the URL for an object.
+      # If the object is not persisted, a form for that object, for instance,
+      # will route to the create action. If it is persisted, a form for the
+      # object will route to the update action.
       def test_persisted?
         assert model.respond_to?(:persisted?), "The model should respond to persisted?"
         assert_boolean model.persisted?, "persisted?"
       end
 
-      # == \Naming
+      # Passes if the object's model responds to <tt>model_name</tt> both as
+      # an instance method and as a class method, and if calling this method
+      # returns a string with some convenience methods: <tt>:human</tt>,
+      # <tt>:singular</tt> and <tt>:plural</tt>.
       #
-      # Model.model_name and Model#model_name must return a string with some
-      # convenience methods: # <tt>:human</tt>, <tt>:singular</tt> and
-      # <tt>:plural</tt>. Check ActiveModel::Naming for more information.
+      # Check ActiveModel::Naming for more information.
       def test_model_naming
         assert model.class.respond_to?(:model_name), "The model class should respond to model_name"
         model_name = model.class.model_name
@@ -88,12 +89,15 @@ module ActiveModel
         assert_equal model.model_name, model.class.model_name
       end
 
-      # == \Errors Testing
+      # Passes if the object's model responds to <tt>errors</tt> and if calling
+      # <tt>[](attribute)</tt> on the result of this method returns an array.
+      # Fails otherwise.
       #
-      # Returns an object that implements [](attribute) defined which returns an
-      # Array of Strings that are the errors for the attribute in question.
-      # If localization is used, the Strings should be localized for the current
-      # locale. If no error is present, this method should return an empty Array.
+      # <tt>errors[attribute]</tt> is used to retrieve the errors of a model
+      # for a given attribute. If errors are present, the method should return
+      # an array of strings that are the errors for the attribute in question.
+      # If localization is used, the strings should be localized for the current
+      # locale. If no error is present, the method should return an empty array.
       def test_errors_aref
         assert model.respond_to?(:errors), "The model should respond to errors"
         assert model.errors[:hello].is_a?(Array), "errors#[] should return an Array"
diff --git a/activemodel/lib/active_model/locale/en.yml b/activemodel/lib/active_model/locale/en.yml
index bf07945fe1..061e35dd1e 100644
--- a/activemodel/lib/active_model/locale/en.yml
+++ b/activemodel/lib/active_model/locale/en.yml
@@ -6,6 +6,7 @@ en:
     # The values :model, :attribute and :value are always available for interpolation
     # The value :count is available when applicable. Can be used for pluralization.
     messages:
+      model_invalid: "Validation failed: %{errors}"
       inclusion: "is not included in the list"
       exclusion: "is reserved"
       invalid: "is invalid"
@@ -16,7 +17,7 @@ en:
       present: "must be blank"
       too_long:
         one: "is too long (maximum is 1 character)"
-        other: "is too long (maximum is %{count} characters)" 
+        other: "is too long (maximum is %{count} characters)"
       too_short:
         one: "is too short (minimum is 1 character)"
         other: "is too short (minimum is %{count} characters)"
diff --git a/activemodel/lib/active_model/model.rb b/activemodel/lib/active_model/model.rb
index d51d6ddcc9..dac8d549a7 100644
--- a/activemodel/lib/active_model/model.rb
+++ b/activemodel/lib/active_model/model.rb
@@ -57,6 +57,7 @@ module ActiveModel
   # (see below).
   module Model
     extend ActiveSupport::Concern
+    include ActiveModel::AttributeAssignment
     include ActiveModel::Validations
     include ActiveModel::Conversion
 
@@ -75,10 +76,8 @@ module ActiveModel
     #   person = Person.new(name: 'bob', age: '18')
     #   person.name # => "bob"
     #   person.age  # => "18"
-    def initialize(params={})
-      params.each do |attr, value|
-        self.public_send("#{attr}=", value)
-      end if params
+    def initialize(attributes={})
+      assign_attributes(attributes) if attributes
 
       super()
     end
diff --git a/activemodel/lib/active_model/naming.rb b/activemodel/lib/active_model/naming.rb
index ada1f9a4f3..d86ef6224e 100644
--- a/activemodel/lib/active_model/naming.rb
+++ b/activemodel/lib/active_model/naming.rb
@@ -1,5 +1,7 @@
 require 'active_support/core_ext/hash/except'
 require 'active_support/core_ext/module/introspection'
+require 'active_support/core_ext/module/remove_method'
+require 'active_support/core_ext/module/delegation'
 
 module ActiveModel
   class Name
@@ -129,7 +131,7 @@ module ActiveModel
     #
     # Equivalent to +to_s+.
     delegate :==, :===, :<=>, :=~, :"!~", :eql?, :to_s,
-             :to_str, to: :name
+             :to_str, :as_json, to: :name
 
     # Returns a new ActiveModel::Name instance. By default, the +namespace+
     # and +name+ option will take the namespace and name of the given class
@@ -162,7 +164,7 @@ module ActiveModel
       @route_key << "_index" if @plural == @singular
     end
 
-    # Transform the model name into a more humane format, using I18n. By default,
+    # Transform the model name into a more human format, using I18n. By default,
     # it will underscore then humanize the class name.
     #
     #   class BlogPost
@@ -190,7 +192,7 @@ module ActiveModel
     private
 
     def _singularize(string)
-      ActiveSupport::Inflector.underscore(string).tr('/', '_')
+      ActiveSupport::Inflector.underscore(string).tr('/'.freeze, '_'.freeze)
     end
   end
 
@@ -224,7 +226,7 @@ module ActiveModel
     # (See ActiveModel::Name for more information).
     #
     #   class Person
-    #     include ActiveModel::Model
+    #     extend ActiveModel::Naming
     #   end
     #
     #   Person.model_name.name     # => "Person"
diff --git a/activemodel/lib/active_model/secure_password.rb b/activemodel/lib/active_model/secure_password.rb
index 871031ece4..89da74efa8 100644
--- a/activemodel/lib/active_model/secure_password.rb
+++ b/activemodel/lib/active_model/secure_password.rb
@@ -26,7 +26,7 @@ module ActiveModel
       # it). When this attribute has a +nil+ value, the validation will not be
       # triggered.
       #
-      # For further customizability, it is possible to supress the default
+      # For further customizability, it is possible to suppress the default
       # validations by passing <tt>validations: false</tt> as an argument.
       #
       # Add bcrypt (~> 3.1.7) to Gemfile to use #has_secure_password:
diff --git a/activemodel/lib/active_model/serialization.rb b/activemodel/lib/active_model/serialization.rb
index 976f50b13e..70e10fa06d 100644
--- a/activemodel/lib/active_model/serialization.rb
+++ b/activemodel/lib/active_model/serialization.rb
@@ -31,16 +31,14 @@ module ActiveModel
   # of the attributes hash's keys. In order to override this behavior, take a look
   # at the private method +read_attribute_for_serialization+.
   #
-  # Most of the time though, either the JSON or XML serializations are needed.
-  # Both of these modules automatically include the
-  # <tt>ActiveModel::Serialization</tt> module, so there is no need to
-  # explicitly include it.
+  # ActiveModel::Serializers::JSON module automatically includes
+  # the <tt>ActiveModel::Serialization</tt> module, so there is no need to
+  # explicitly include <tt>ActiveModel::Serialization</tt>.
   #
-  # A minimal implementation including XML and JSON would be:
+  # A minimal implementation including JSON would be:
   #
   #   class Person
   #     include ActiveModel::Serializers::JSON
-  #     include ActiveModel::Serializers::Xml
   #
   #     attr_accessor :name
   #
@@ -55,13 +53,11 @@ module ActiveModel
   #   person.serializable_hash   # => {"name"=>nil}
   #   person.as_json             # => {"name"=>nil}
   #   person.to_json             # => "{\"name\":null}"
-  #   person.to_xml              # => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<serial-person...
   #
   #   person.name = "Bob"
   #   person.serializable_hash   # => {"name"=>"Bob"}
   #   person.as_json             # => {"name"=>"Bob"}
   #   person.to_json             # => "{\"name\":\"Bob\"}"
-  #   person.to_xml              # => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<serial-person...
   #
   # Valid options are <tt>:only</tt>, <tt>:except</tt>, <tt>:methods</tt> and
   # <tt>:include</tt>. The following are all valid examples:
@@ -94,6 +90,37 @@ module ActiveModel
     #   person.serializable_hash(except: :name) # => {"age"=>22}
     #   person.serializable_hash(methods: :capitalized_name)
     #   # => {"name"=>"bob", "age"=>22, "capitalized_name"=>"Bob"}
+    #
+    # Example with <tt>:include</tt> option
+    #
+    #   class User
+    #     include ActiveModel::Serializers::JSON
+    #     attr_accessor :name, :notes # Emulate has_many :notes
+    #     def attributes
+    #       {'name' => nil}
+    #     end
+    #   end
+    #
+    #   class Note
+    #     include ActiveModel::Serializers::JSON
+    #     attr_accessor :title, :text
+    #     def attributes
+    #       {'title' => nil, 'text' => nil}
+    #     end
+    #   end
+    #
+    #   note = Note.new
+    #   note.title = 'Battle of Austerlitz'
+    #   note.text = 'Some text here'
+    #
+    #   user = User.new
+    #   user.name = 'Napoleon'
+    #   user.notes = [note]
+    #
+    #   user.serializable_hash
+    #   # => {"name" => "Napoleon"}
+    #   user.serializable_hash(include: { notes: { only: 'title' }})
+    #   # => {"name" => "Napoleon", "notes" => [{"title"=>"Battle of Austerlitz"}]}
     def serializable_hash(options = nil)
       options ||= {}
 
@@ -107,7 +134,7 @@ module ActiveModel
       hash = {}
       attribute_names.each { |n| hash[n] = read_attribute_for_serialization(n) }
 
-      Array(options[:methods]).each { |m| hash[m.to_s] = send(m) if respond_to?(m) }
+      Array(options[:methods]).each { |m| hash[m.to_s] = send(m) }
 
       serializable_add_includes(options) do |association, records, opts|
         hash[association.to_s] = if records.respond_to?(:to_ary)
diff --git a/activemodel/lib/active_model/serializers/xml.rb b/activemodel/lib/active_model/serializers/xml.rb
deleted file mode 100644
index e33c766627..0000000000
--- a/activemodel/lib/active_model/serializers/xml.rb
+++ /dev/null
@@ -1,238 +0,0 @@
-require 'active_support/core_ext/module/attribute_accessors'
-require 'active_support/core_ext/array/conversions'
-require 'active_support/core_ext/hash/conversions'
-require 'active_support/core_ext/hash/slice'
-require 'active_support/core_ext/time/acts_like'
-
-module ActiveModel
-  module Serializers
-    # == \Active \Model XML Serializer
-    module Xml
-      extend ActiveSupport::Concern
-      include ActiveModel::Serialization
-
-      included do
-        extend ActiveModel::Naming
-      end
-
-      class Serializer #:nodoc:
-        class Attribute #:nodoc:
-          attr_reader :name, :value, :type
-
-          def initialize(name, serializable, value)
-            @name, @serializable = name, serializable
-
-            if value.acts_like?(:time) && value.respond_to?(:in_time_zone)
-              value  = value.in_time_zone
-            end
-
-            @value = value
-            @type  = compute_type
-          end
-
-          def decorations
-            decorations = {}
-            decorations[:encoding] = 'base64' if type == :binary
-            decorations[:type] = (type == :string) ? nil : type
-            decorations[:nil] = true if value.nil?
-            decorations
-          end
-
-        protected
-
-          def compute_type
-            return if value.nil?
-            type = ActiveSupport::XmlMini::TYPE_NAMES[value.class.name]
-            type ||= :string if value.respond_to?(:to_str)
-            type ||= :yaml
-            type
-          end
-        end
-
-        class MethodAttribute < Attribute #:nodoc:
-        end
-
-        attr_reader :options
-
-        def initialize(serializable, options = nil)
-          @serializable = serializable
-          @options = options ? options.dup : {}
-        end
-
-        def serializable_hash
-          @serializable.serializable_hash(@options.except(:include))
-        end
-
-        def serializable_collection
-          methods = Array(options[:methods]).map(&:to_s)
-          serializable_hash.map do |name, value|
-            name = name.to_s
-            if methods.include?(name)
-              self.class::MethodAttribute.new(name, @serializable, value)
-            else
-              self.class::Attribute.new(name, @serializable, value)
-            end
-          end
-        end
-
-        def serialize
-          require 'builder' unless defined? ::Builder
-
-          options[:indent]  ||= 2
-          options[:builder] ||= ::Builder::XmlMarkup.new(indent: options[:indent])
-
-          @builder = options[:builder]
-          @builder.instruct! unless options[:skip_instruct]
-
-          root = (options[:root] || @serializable.model_name.element).to_s
-          root = ActiveSupport::XmlMini.rename_key(root, options)
-
-          args = [root]
-          args << { xmlns: options[:namespace] } if options[:namespace]
-          args << { type: options[:type] } if options[:type] && !options[:skip_types]
-
-          @builder.tag!(*args) do
-            add_attributes_and_methods
-            add_includes
-            add_extra_behavior
-            add_procs
-            yield @builder if block_given?
-          end
-        end
-
-      private
-
-        def add_extra_behavior
-        end
-
-        def add_attributes_and_methods
-          serializable_collection.each do |attribute|
-            key = ActiveSupport::XmlMini.rename_key(attribute.name, options)
-            ActiveSupport::XmlMini.to_tag(key, attribute.value,
-              options.merge(attribute.decorations))
-          end
-        end
-
-        def add_includes
-          @serializable.send(:serializable_add_includes, options) do |association, records, opts|
-            add_associations(association, records, opts)
-          end
-        end
-
-        # TODO: This can likely be cleaned up to simple use ActiveSupport::XmlMini.to_tag as well.
-        def add_associations(association, records, opts)
-          merged_options = opts.merge(options.slice(:builder, :indent))
-          merged_options[:skip_instruct] = true
-
-          [:skip_types, :dasherize, :camelize].each do |key|
-            merged_options[key] = options[key] if merged_options[key].nil? && !options[key].nil?
-          end
-
-          if records.respond_to?(:to_ary)
-            records = records.to_ary
-
-            tag  = ActiveSupport::XmlMini.rename_key(association.to_s, options)
-            type = options[:skip_types] ? { } : { type: "array" }
-            association_name = association.to_s.singularize
-            merged_options[:root] = association_name
-
-            if records.empty?
-              @builder.tag!(tag, type)
-            else
-              @builder.tag!(tag, type) do
-                records.each do |record|
-                  if options[:skip_types]
-                    record_type = {}
-                  else
-                    record_class = (record.class.to_s.underscore == association_name) ? nil : record.class.name
-                    record_type = { type: record_class }
-                  end
-
-                  record.to_xml merged_options.merge(record_type)
-                end
-              end
-            end
-          else
-            merged_options[:root] = association.to_s
-
-            unless records.class.to_s.underscore == association.to_s
-              merged_options[:type] = records.class.name
-            end
-
-            records.to_xml merged_options
-          end
-        end
-
-        def add_procs
-          if procs = options.delete(:procs)
-            Array(procs).each do |proc|
-              if proc.arity == 1
-                proc.call(options)
-              else
-                proc.call(options, @serializable)
-              end
-            end
-          end
-        end
-      end
-
-      # Returns XML representing the model. Configuration can be
-      # passed through +options+.
-      #
-      # Without any +options+, the returned XML string will include all the
-      # model's attributes.
-      #
-      #   user = User.find(1)
-      #   user.to_xml
-      #
-      #   <?xml version="1.0" encoding="UTF-8"?>
-      #   <user>
-      #     <id type="integer">1</id>
-      #     <name>David</name>
-      #     <age type="integer">16</age>
-      #     <created-at type="dateTime">2011-01-30T22:29:23Z</created-at>
-      #   </user>
-      #
-      # The <tt>:only</tt> and <tt>:except</tt> options can be used to limit the
-      # attributes included, and work similar to the +attributes+ method.
-      #
-      # To include the result of some method calls on the model use <tt>:methods</tt>.
-      #
-      # To include associations use <tt>:include</tt>.
-      #
-      # For further documentation, see <tt>ActiveRecord::Serialization#to_xml</tt>
-      def to_xml(options = {}, &block)
-        Serializer.new(self, options).serialize(&block)
-      end
-
-      # Sets the model +attributes+ from an XML string. Returns +self+.
-      #
-      #   class Person
-      #     include ActiveModel::Serializers::Xml
-      #
-      #     attr_accessor :name, :age, :awesome
-      #
-      #     def attributes=(hash)
-      #       hash.each do |key, value|
-      #         instance_variable_set("@#{key}", value)
-      #       end
-      #     end
-      #
-      #     def attributes
-      #       instance_values
-      #     end
-      #   end
-      #
-      #   xml = { name: 'bob', age: 22, awesome:true }.to_xml
-      #   person = Person.new
-      #   person.from_xml(xml) # => #<Person:0x007fec5e3b3c40 @age=22, @awesome=true, @name="bob">
-      #   person.name          # => "bob"
-      #   person.age           # => 22
-      #   person.awesome       # => true
-      def from_xml(xml)
-        self.attributes = Hash.from_xml(xml).values.first
-        self
-      end
-    end
-  end
-end
diff --git a/activemodel/lib/active_model/type.rb b/activemodel/lib/active_model/type.rb
new file mode 100644
index 0000000000..bec851594f
--- /dev/null
+++ b/activemodel/lib/active_model/type.rb
@@ -0,0 +1,59 @@
+require 'active_model/type/helpers'
+require 'active_model/type/value'
+
+require 'active_model/type/big_integer'
+require 'active_model/type/binary'
+require 'active_model/type/boolean'
+require 'active_model/type/date'
+require 'active_model/type/date_time'
+require 'active_model/type/decimal'
+require 'active_model/type/decimal_without_scale'
+require 'active_model/type/float'
+require 'active_model/type/immutable_string'
+require 'active_model/type/integer'
+require 'active_model/type/string'
+require 'active_model/type/text'
+require 'active_model/type/time'
+require 'active_model/type/unsigned_integer'
+
+require 'active_model/type/registry'
+
+module ActiveModel
+  module Type
+    @registry = Registry.new
+
+    class << self
+      attr_accessor :registry # :nodoc:
+      delegate :add_modifier, to: :registry
+
+      # Add a new type to the registry, allowing it to be referenced as a
+      # symbol by ActiveModel::Attributes::ClassMethods#attribute.  If your
+      # type is only meant to be used with a specific database adapter, you can
+      # do so by passing +adapter: :postgresql+. If your type has the same
+      # name as a native type for the current adapter, an exception will be
+      # raised unless you specify an +:override+ option. +override: true+ will
+      # cause your type to be used instead of the native type. +override:
+      # false+ will cause the native type to be used over yours if one exists.
+      def register(type_name, klass = nil, **options, &block)
+        registry.register(type_name, klass, **options, &block)
+      end
+
+      def lookup(*args, **kwargs) # :nodoc:
+        registry.lookup(*args, **kwargs)
+      end
+    end
+
+    register(:big_integer, Type::BigInteger)
+    register(:binary, Type::Binary)
+    register(:boolean, Type::Boolean)
+    register(:date, Type::Date)
+    register(:date_time, Type::DateTime)
+    register(:decimal, Type::Decimal)
+    register(:float, Type::Float)
+    register(:immutable_string, Type::ImmutableString)
+    register(:integer, Type::Integer)
+    register(:string, Type::String)
+    register(:text, Type::Text)
+    register(:time, Type::Time)
+  end
+end
diff --git a/activerecord/lib/active_record/type/big_integer.rb b/activemodel/lib/active_model/type/big_integer.rb
index 0c72d8914f..4168cbfce7 100644
--- a/activerecord/lib/active_record/type/big_integer.rb
+++ b/activemodel/lib/active_model/type/big_integer.rb
@@ -1,6 +1,6 @@
-require 'active_record/type/integer'
+require 'active_model/type/integer'
 
-module ActiveRecord
+module ActiveModel
   module Type
     class BigInteger < Integer # :nodoc:
       private
diff --git a/activerecord/lib/active_record/type/binary.rb b/activemodel/lib/active_model/type/binary.rb
index 005a48ef0d..a0cc45b4c3 100644
--- a/activerecord/lib/active_record/type/binary.rb
+++ b/activemodel/lib/active_model/type/binary.rb
@@ -1,4 +1,4 @@
-module ActiveRecord
+module ActiveModel
   module Type
     class Binary < Value # :nodoc:
       def type
@@ -9,7 +9,7 @@ module ActiveRecord
         true
       end
 
-      def type_cast(value)
+      def cast(value)
         if value.is_a?(Data)
           value.to_s
         else
@@ -17,13 +17,13 @@ module ActiveRecord
         end
       end
 
-      def type_cast_for_database(value)
+      def serialize(value)
         return if value.nil?
         Data.new(super)
       end
 
       def changed_in_place?(raw_old_value, value)
-        old_value = type_cast_from_database(raw_old_value)
+        old_value = deserialize(raw_old_value)
         old_value != value
       end
 
diff --git a/activerecord/lib/active_record/type/boolean.rb b/activemodel/lib/active_model/type/boolean.rb
index f6a75512fd..c1bce98c87 100644
--- a/activerecord/lib/active_record/type/boolean.rb
+++ b/activemodel/lib/active_model/type/boolean.rb
@@ -1,6 +1,8 @@
-module ActiveRecord
+module ActiveModel
   module Type
     class Boolean < Value # :nodoc:
+      FALSE_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE', 'off', 'OFF'].to_set
+
       def type
         :boolean
       end
@@ -11,7 +13,7 @@ module ActiveRecord
         if value == ''
           nil
         else
-          !ConnectionAdapters::Column::FALSE_VALUES.include?(value)
+          !FALSE_VALUES.include?(value)
         end
       end
     end
diff --git a/activemodel/lib/active_model/type/date.rb b/activemodel/lib/active_model/type/date.rb
new file mode 100644
index 0000000000..f74243a22c
--- /dev/null
+++ b/activemodel/lib/active_model/type/date.rb
@@ -0,0 +1,50 @@
+module ActiveModel
+  module Type
+    class Date < Value # :nodoc:
+      include Helpers::AcceptsMultiparameterTime.new
+
+      def type
+        :date
+      end
+
+      def type_cast_for_schema(value)
+        "'#{value.to_s(:db)}'"
+      end
+
+      private
+
+      def cast_value(value)
+        if value.is_a?(::String)
+          return if value.empty?
+          fast_string_to_date(value) || fallback_string_to_date(value)
+        elsif value.respond_to?(:to_date)
+          value.to_date
+        else
+          value
+        end
+      end
+
+      ISO_DATE = /\A(\d{4})-(\d\d)-(\d\d)\z/
+      def fast_string_to_date(string)
+        if string =~ ISO_DATE
+          new_date $1.to_i, $2.to_i, $3.to_i
+        end
+      end
+
+      def fallback_string_to_date(string)
+        new_date(*::Date._parse(string, false).values_at(:year, :mon, :mday))
+      end
+
+      def new_date(year, mon, mday)
+        if year && year != 0
+          ::Date.new(year, mon, mday) rescue nil
+        end
+      end
+
+      def value_from_multiparameter_assignment(*)
+        time = super
+        time && time.to_date
+      end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/type/date_time.rb b/activemodel/lib/active_model/type/date_time.rb
new file mode 100644
index 0000000000..2f2df4320f
--- /dev/null
+++ b/activemodel/lib/active_model/type/date_time.rb
@@ -0,0 +1,44 @@
+module ActiveModel
+  module Type
+    class DateTime < Value # :nodoc:
+      include Helpers::TimeValue
+      include Helpers::AcceptsMultiparameterTime.new(
+        defaults: { 4 => 0, 5 => 0 }
+      )
+
+      def type
+        :datetime
+      end
+
+      private
+
+      def cast_value(value)
+        return apply_seconds_precision(value) unless value.is_a?(::String)
+        return if value.empty?
+
+        fast_string_to_time(value) || fallback_string_to_time(value)
+      end
+
+      # '0.123456' -> 123456
+      # '1.123456' -> 123456
+      def microseconds(time)
+        time[:sec_fraction] ? (time[:sec_fraction] * 1_000_000).to_i : 0
+      end
+
+      def fallback_string_to_time(string)
+        time_hash = ::Date._parse(string)
+        time_hash[:sec_fraction] = microseconds(time_hash)
+
+        new_time(*time_hash.values_at(:year, :mon, :mday, :hour, :min, :sec, :sec_fraction, :offset))
+      end
+
+      def value_from_multiparameter_assignment(values_hash)
+        missing_parameter = (1..3).detect { |key| !values_hash.key?(key) }
+        if missing_parameter
+          raise ArgumentError, missing_parameter
+        end
+        super
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/type/decimal.rb b/activemodel/lib/active_model/type/decimal.rb
index 7b2bee2c42..d19d8baada 100644
--- a/activerecord/lib/active_record/type/decimal.rb
+++ b/activemodel/lib/active_model/type/decimal.rb
@@ -1,20 +1,22 @@
-module ActiveRecord
+require "bigdecimal/util"
+
+module ActiveModel
   module Type
     class Decimal < Value # :nodoc:
-      include Numeric
+      include Helpers::Numeric
 
       def type
         :decimal
       end
 
       def type_cast_for_schema(value)
-        value.to_s
+        value.to_s.inspect
       end
 
       private
 
       def cast_value(value)
-        case value
+        casted_value = case value
         when ::Float
           convert_float_to_big_decimal(value)
         when ::Numeric, ::String
@@ -26,6 +28,8 @@ module ActiveRecord
             cast_value(value.to_s)
           end
         end
+
+        scale ? casted_value.round(scale) : casted_value
       end
 
       def convert_float_to_big_decimal(value)
diff --git a/activerecord/lib/active_record/type/decimal_without_scale.rb b/activemodel/lib/active_model/type/decimal_without_scale.rb
index ff5559e300..129baa0c10 100644
--- a/activerecord/lib/active_record/type/decimal_without_scale.rb
+++ b/activemodel/lib/active_model/type/decimal_without_scale.rb
@@ -1,6 +1,6 @@
-require 'active_record/type/big_integer'
+require 'active_model/type/big_integer'
 
-module ActiveRecord
+module ActiveModel
   module Type
     class DecimalWithoutScale < BigInteger # :nodoc:
       def type
diff --git a/activemodel/lib/active_model/type/float.rb b/activemodel/lib/active_model/type/float.rb
new file mode 100644
index 0000000000..0f925bc7e1
--- /dev/null
+++ b/activemodel/lib/active_model/type/float.rb
@@ -0,0 +1,25 @@
+module ActiveModel
+  module Type
+    class Float < Value # :nodoc:
+      include Helpers::Numeric
+
+      def type
+        :float
+      end
+
+      alias serialize cast
+
+      private
+
+      def cast_value(value)
+        case value
+        when ::Float then value
+        when "Infinity" then ::Float::INFINITY
+        when "-Infinity" then -::Float::INFINITY
+        when "NaN" then ::Float::NAN
+        else value.to_f
+        end
+      end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/type/helpers.rb b/activemodel/lib/active_model/type/helpers.rb
new file mode 100644
index 0000000000..a805a359ab
--- /dev/null
+++ b/activemodel/lib/active_model/type/helpers.rb
@@ -0,0 +1,4 @@
+require 'active_model/type/helpers/accepts_multiparameter_time'
+require 'active_model/type/helpers/numeric'
+require 'active_model/type/helpers/mutable'
+require 'active_model/type/helpers/time_value'
diff --git a/activemodel/lib/active_model/type/helpers/accepts_multiparameter_time.rb b/activemodel/lib/active_model/type/helpers/accepts_multiparameter_time.rb
new file mode 100644
index 0000000000..facea12704
--- /dev/null
+++ b/activemodel/lib/active_model/type/helpers/accepts_multiparameter_time.rb
@@ -0,0 +1,35 @@
+module ActiveModel
+  module Type
+    module Helpers
+      class AcceptsMultiparameterTime < Module # :nodoc:
+        def initialize(defaults: {})
+          define_method(:cast) do |value|
+            if value.is_a?(Hash)
+              value_from_multiparameter_assignment(value)
+            else
+              super(value)
+            end
+          end
+
+          define_method(:assert_valid_value) do |value|
+            if value.is_a?(Hash)
+              value_from_multiparameter_assignment(value)
+            else
+              super(value)
+            end
+          end
+
+          define_method(:value_from_multiparameter_assignment) do |values_hash|
+            defaults.each do |k, v|
+              values_hash[k] ||= v
+            end
+            return unless values_hash[1] && values_hash[2] && values_hash[3]
+            values = values_hash.sort.map(&:last)
+            ::Time.send(default_timezone, *values)
+          end
+          private :value_from_multiparameter_assignment
+        end
+      end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/type/helpers/mutable.rb b/activemodel/lib/active_model/type/helpers/mutable.rb
new file mode 100644
index 0000000000..4dddbe4e5e
--- /dev/null
+++ b/activemodel/lib/active_model/type/helpers/mutable.rb
@@ -0,0 +1,18 @@
+module ActiveModel
+  module Type
+    module Helpers
+      module Mutable # :nodoc:
+        def cast(value)
+          deserialize(serialize(value))
+        end
+
+        # +raw_old_value+ will be the `_before_type_cast` version of the
+        # value (likely a string). +new_value+ will be the current, type
+        # cast value.
+        def changed_in_place?(raw_old_value, new_value)
+          raw_old_value != serialize(new_value)
+        end
+      end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/type/helpers/numeric.rb b/activemodel/lib/active_model/type/helpers/numeric.rb
new file mode 100644
index 0000000000..c883010506
--- /dev/null
+++ b/activemodel/lib/active_model/type/helpers/numeric.rb
@@ -0,0 +1,34 @@
+module ActiveModel
+  module Type
+    module Helpers
+      module Numeric # :nodoc:
+        def cast(value)
+          value = case value
+                  when true then 1
+                  when false then 0
+                  when ::String then value.presence
+                  else value
+                  end
+          super(value)
+        end
+
+        def changed?(old_value, _new_value, new_value_before_type_cast) # :nodoc:
+          super || number_to_non_number?(old_value, new_value_before_type_cast)
+        end
+
+        private
+
+        def number_to_non_number?(old_value, new_value_before_type_cast)
+          old_value != nil && non_numeric_string?(new_value_before_type_cast)
+        end
+
+        def non_numeric_string?(value)
+          # 'wibble'.to_i will give zero, we want to make sure
+          # that we aren't marking int zero to string zero as
+          # changed.
+          value.to_s !~ /\A-?\d+\.?\d*\z/
+        end
+      end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/type/helpers/time_value.rb b/activemodel/lib/active_model/type/helpers/time_value.rb
new file mode 100644
index 0000000000..63993c0d93
--- /dev/null
+++ b/activemodel/lib/active_model/type/helpers/time_value.rb
@@ -0,0 +1,77 @@
+require "active_support/core_ext/time/zones"
+
+module ActiveModel
+  module Type
+    module Helpers
+      module TimeValue # :nodoc:
+        def serialize(value)
+          value = apply_seconds_precision(value)
+
+          if value.acts_like?(:time)
+            zone_conversion_method = is_utc? ? :getutc : :getlocal
+
+            if value.respond_to?(zone_conversion_method)
+              value = value.send(zone_conversion_method)
+            end
+          end
+
+          value
+        end
+
+        def is_utc?
+          ::Time.zone_default.nil? || ::Time.zone_default =~ 'UTC'
+        end
+
+        def default_timezone
+          if is_utc?
+            :utc
+          else
+            :local
+          end
+        end
+
+        def apply_seconds_precision(value)
+          return value unless precision && value.respond_to?(:usec)
+          number_of_insignificant_digits = 6 - precision
+          round_power = 10 ** number_of_insignificant_digits
+          value.change(usec: value.usec / round_power * round_power)
+        end
+
+        def type_cast_for_schema(value)
+          "'#{value.to_s(:db)}'"
+        end
+
+        def user_input_in_time_zone(value)
+          value.in_time_zone
+        end
+
+        private
+
+        def new_time(year, mon, mday, hour, min, sec, microsec, offset = nil)
+          # Treat 0000-00-00 00:00:00 as nil.
+          return if year.nil? || (year == 0 && mon == 0 && mday == 0)
+
+          if offset
+            time = ::Time.utc(year, mon, mday, hour, min, sec, microsec) rescue nil
+            return unless time
+
+            time -= offset
+            is_utc? ? time : time.getlocal
+          else
+            ::Time.public_send(default_timezone, year, mon, mday, hour, min, sec, microsec) rescue nil
+          end
+        end
+
+        ISO_DATETIME = /\A(\d{4})-(\d\d)-(\d\d) (\d\d):(\d\d):(\d\d)(\.\d+)?\z/
+
+        # Doesn't handle time zones.
+        def fast_string_to_time(string)
+          if string =~ ISO_DATETIME
+            microsec = ($7.to_r * 1_000_000).to_i
+            new_time $1.to_i, $2.to_i, $3.to_i, $4.to_i, $5.to_i, $6.to_i, microsec
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/type/immutable_string.rb b/activemodel/lib/active_model/type/immutable_string.rb
new file mode 100644
index 0000000000..20b8ca0cc4
--- /dev/null
+++ b/activemodel/lib/active_model/type/immutable_string.rb
@@ -0,0 +1,29 @@
+module ActiveModel
+  module Type
+    class ImmutableString < Value # :nodoc:
+      def type
+        :string
+      end
+
+      def serialize(value)
+        case value
+        when ::Numeric, ActiveSupport::Duration then value.to_s
+        when true then "t"
+        when false then "f"
+        else super
+        end
+      end
+
+      private
+
+      def cast_value(value)
+        result = case value
+                 when true then "t"
+                 when false then "f"
+                 else value.to_s
+                 end
+        result.freeze
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/type/integer.rb b/activemodel/lib/active_model/type/integer.rb
index 394fe008f9..2f73ede009 100644
--- a/activerecord/lib/active_record/type/integer.rb
+++ b/activemodel/lib/active_model/type/integer.rb
@@ -1,7 +1,7 @@
-module ActiveRecord
+module ActiveModel
   module Type
     class Integer < Value # :nodoc:
-      include Numeric
+      include Helpers::Numeric
 
       # Column storage size in bytes.
       # 4 bytes means a MySQL int or Postgres integer as opposed to smallint etc.
@@ -16,13 +16,19 @@ module ActiveRecord
         :integer
       end
 
-      alias type_cast_for_database type_cast
-
-      def type_cast_from_database(value)
+      def deserialize(value)
         return if value.nil?
         value.to_i
       end
 
+      def serialize(value)
+        result = cast(value)
+        if result
+          ensure_in_range(result)
+        end
+        result
+      end
+
       protected
 
       attr_reader :range
@@ -34,26 +40,27 @@ module ActiveRecord
         when true then 1
         when false then 0
         else
-          result = value.to_i rescue nil
-          ensure_in_range(result) if result
-          result
+          value.to_i rescue nil
         end
       end
 
       def ensure_in_range(value)
         unless range.cover?(value)
-          raise RangeError, "#{value} is out of range for #{self.class} with limit #{limit || DEFAULT_LIMIT}"
+          raise RangeError, "#{value} is out of range for #{self.class} with limit #{_limit}"
         end
       end
 
       def max_value
-        limit = self.limit || DEFAULT_LIMIT
-        1 << (limit * 8 - 1) # 8 bits per byte with one bit for sign
+        1 << (_limit * 8 - 1) # 8 bits per byte with one bit for sign
       end
 
       def min_value
         -max_value
       end
+
+      def _limit
+        self.limit || DEFAULT_LIMIT
+      end
     end
   end
 end
diff --git a/activemodel/lib/active_model/type/registry.rb b/activemodel/lib/active_model/type/registry.rb
new file mode 100644
index 0000000000..adc88eb624
--- /dev/null
+++ b/activemodel/lib/active_model/type/registry.rb
@@ -0,0 +1,64 @@
+module ActiveModel
+  # :stopdoc:
+  module Type
+    class Registry
+      def initialize
+        @registrations = []
+      end
+
+      def register(type_name, klass = nil, **options, &block)
+        block ||= proc { |_, *args| klass.new(*args) }
+        registrations << registration_klass.new(type_name, block, **options)
+      end
+
+      def lookup(symbol, *args)
+        registration = find_registration(symbol, *args)
+
+        if registration
+          registration.call(self, symbol, *args)
+        else
+          raise ArgumentError, "Unknown type #{symbol.inspect}"
+        end
+      end
+
+      protected
+
+      attr_reader :registrations
+
+      private
+
+      def registration_klass
+        Registration
+      end
+
+      def find_registration(symbol, *args)
+        registrations.find { |r| r.matches?(symbol, *args) }
+      end
+    end
+
+    class Registration
+      # Options must be taken because of https://bugs.ruby-lang.org/issues/10856
+      def initialize(name, block, **)
+        @name = name
+        @block = block
+      end
+
+      def call(_registry, *args, **kwargs)
+        if kwargs.any? # https://bugs.ruby-lang.org/issues/10856
+          block.call(*args, **kwargs)
+        else
+          block.call(*args)
+        end
+      end
+
+      def matches?(type_name, *args, **kwargs)
+        type_name == name
+      end
+
+      protected
+
+      attr_reader :name, :block
+    end
+  end
+  # :startdoc:
+end
diff --git a/activemodel/lib/active_model/type/string.rb b/activemodel/lib/active_model/type/string.rb
new file mode 100644
index 0000000000..8a91410998
--- /dev/null
+++ b/activemodel/lib/active_model/type/string.rb
@@ -0,0 +1,19 @@
+require "active_model/type/immutable_string"
+
+module ActiveModel
+  module Type
+    class String < ImmutableString # :nodoc:
+      def changed_in_place?(raw_old_value, new_value)
+        if new_value.is_a?(::String)
+          raw_old_value != new_value
+        end
+      end
+
+      private
+
+      def cast_value(value)
+        ::String.new(super)
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/type/text.rb b/activemodel/lib/active_model/type/text.rb
index 26f980f060..1ad04daba4 100644
--- a/activerecord/lib/active_record/type/text.rb
+++ b/activemodel/lib/active_model/type/text.rb
@@ -1,6 +1,6 @@
-require 'active_record/type/string'
+require 'active_model/type/string'
 
-module ActiveRecord
+module ActiveModel
   module Type
     class Text < String # :nodoc:
       def type
diff --git a/activemodel/lib/active_model/type/time.rb b/activemodel/lib/active_model/type/time.rb
new file mode 100644
index 0000000000..7101bad566
--- /dev/null
+++ b/activemodel/lib/active_model/type/time.rb
@@ -0,0 +1,42 @@
+module ActiveModel
+  module Type
+    class Time < Value # :nodoc:
+      include Helpers::TimeValue
+      include Helpers::AcceptsMultiparameterTime.new(
+        defaults: { 1 => 1970, 2 => 1, 3 => 1, 4 => 0, 5 => 0 }
+      )
+
+      def type
+        :time
+      end
+
+      def user_input_in_time_zone(value)
+        return unless value.present?
+
+        case value
+        when ::String
+          value = "2000-01-01 #{value}"
+        when ::Time
+          value = value.change(year: 2000, day: 1, month: 1)
+        end
+
+        super(value)
+      end
+
+      private
+
+      def cast_value(value)
+        return value unless value.is_a?(::String)
+        return if value.empty?
+
+        dummy_time_value = "2000-01-01 #{value}"
+
+        fast_string_to_time(dummy_time_value) || begin
+          time_hash = ::Date._parse(dummy_time_value)
+          return if time_hash[:hour].nil?
+          new_time(*time_hash.values_at(:year, :mon, :mday, :hour, :min, :sec, :sec_fraction))
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/type/unsigned_integer.rb b/activemodel/lib/active_model/type/unsigned_integer.rb
index ed3e527483..3f49f9f5f7 100644
--- a/activerecord/lib/active_record/type/unsigned_integer.rb
+++ b/activemodel/lib/active_model/type/unsigned_integer.rb
@@ -1,4 +1,4 @@
-module ActiveRecord
+module ActiveModel
   module Type
     class UnsignedInteger < Integer # :nodoc:
       private
diff --git a/activemodel/lib/active_model/type/value.rb b/activemodel/lib/active_model/type/value.rb
new file mode 100644
index 0000000000..5fea0561a6
--- /dev/null
+++ b/activemodel/lib/active_model/type/value.rb
@@ -0,0 +1,107 @@
+module ActiveModel
+  module Type
+    class Value
+      attr_reader :precision, :scale, :limit
+
+      def initialize(precision: nil, limit: nil, scale: nil)
+        @precision = precision
+        @scale = scale
+        @limit = limit
+      end
+
+      def type # :nodoc:
+      end
+
+      # Converts a value from database input to the appropriate ruby type. The
+      # return value of this method will be returned from
+      # ActiveRecord::AttributeMethods::Read#read_attribute. The default
+      # implementation just calls Value#cast.
+      #
+      # +value+ The raw input, as provided from the database.
+      def deserialize(value)
+        cast(value)
+      end
+
+      # Type casts a value from user input (e.g. from a setter). This value may
+      # be a string from the form builder, or a ruby object passed to a setter.
+      # There is currently no way to differentiate between which source it came
+      # from.
+      #
+      # The return value of this method will be returned from
+      # ActiveRecord::AttributeMethods::Read#read_attribute. See also:
+      # Value#cast_value.
+      #
+      # +value+ The raw input, as provided to the attribute setter.
+      def cast(value)
+        cast_value(value) unless value.nil?
+      end
+
+      # Casts a value from the ruby type to a type that the database knows how
+      # to understand. The returned value from this method should be a
+      # +String+, +Numeric+, +Date+, +Time+, +Symbol+, +true+, +false+, or
+      # +nil+.
+      def serialize(value)
+        value
+      end
+
+      # Type casts a value for schema dumping. This method is private, as we are
+      # hoping to remove it entirely.
+      def type_cast_for_schema(value) # :nodoc:
+        value.inspect
+      end
+
+      # These predicates are not documented, as I need to look further into
+      # their use, and see if they can be removed entirely.
+      def binary? # :nodoc:
+        false
+      end
+
+      # Determines whether a value has changed for dirty checking. +old_value+
+      # and +new_value+ will always be type-cast. Types should not need to
+      # override this method.
+      def changed?(old_value, new_value, _new_value_before_type_cast)
+        old_value != new_value
+      end
+
+      # Determines whether the mutable value has been modified since it was
+      # read. Returns +false+ by default. If your type returns an object
+      # which could be mutated, you should override this method. You will need
+      # to either:
+      #
+      # - pass +new_value+ to Value#serialize and compare it to
+      #   +raw_old_value+
+      #
+      # or
+      #
+      # - pass +raw_old_value+ to Value#deserialize and compare it to
+      #   +new_value+
+      #
+      # +raw_old_value+ The original value, before being passed to
+      # +deserialize+.
+      #
+      # +new_value+ The current value, after type casting.
+      def changed_in_place?(raw_old_value, new_value)
+        false
+      end
+
+      def ==(other)
+        self.class == other.class &&
+          precision == other.precision &&
+          scale == other.scale &&
+          limit == other.limit
+      end
+
+      def assert_valid_value(*)
+      end
+
+      private
+
+      # Convenience method for types which do not need separate type casting
+      # behavior for user and database inputs. Called by Value#cast for
+      # values except +nil+.
+      def cast_value(value) # :doc:
+        value
+      end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index 6a2668b8f7..f23c920d87 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -87,7 +87,7 @@ module ActiveModel
         validates_with BlockValidator, _merge_attributes(attr_names), &block
       end
 
-      VALID_OPTIONS_FOR_VALIDATE = [:on, :if, :unless, :prepend].freeze
+      VALID_OPTIONS_FOR_VALIDATE = [:on, :if, :unless, :prepend].freeze # :nodoc:
 
       # Adds a validation method or block to the class. This is useful when
       # overriding the +validate+ instance method becomes too unwieldy and
@@ -129,6 +129,9 @@ module ActiveModel
       #     end
       #   end
       #
+      # Note that the return value of validation methods is not relevant.
+      # It's not possible to halt the validate callback chain.
+      #
       # Options:
       # * <tt>:on</tt> - Specifies the contexts where this validation is active.
       #   Runs in all validation contexts by default (nil). You can pass a symbol
@@ -159,7 +162,7 @@ module ActiveModel
           options = options.dup
           options[:if] = Array(options[:if])
           options[:if].unshift ->(o) {
-            Array(options[:on]).include?(o.validation_context)
+            !(Array(options[:on]) & Array(o.validation_context)).empty?
           }
         end
 
@@ -371,6 +374,15 @@ module ActiveModel
       !valid?(context)
     end
 
+    # Runs all the validations within the specified context. Returns +true+ if
+    # no errors are found, raises +ValidationError+ otherwise.
+    #
+    # Validations with no <tt>:on</tt> option will run no matter the context. Validations with
+    # some <tt>:on</tt> option will only run in the specified context.
+    def validate!(context = nil)
+      valid?(context) || raise_validation_error
+    end
+
     # Hook method defining how an attribute value should be retrieved. By default
     # this is assumed to be an instance named after the attribute. Override this
     # method in subclasses should you need to retrieve the value for a given
@@ -395,6 +407,30 @@ module ActiveModel
       _run_validate_callbacks
       errors.empty?
     end
+
+    def raise_validation_error
+      raise(ValidationError.new(self))
+    end
+  end
+
+  # = Active Model ValidationError
+  #
+  # Raised by <tt>validate!</tt> when the model is invalid. Use the
+  # +model+ method to retrieve the record which did not validate.
+  #
+  #   begin
+  #     complex_operation_that_internally_calls_validate!
+  #   rescue ActiveModel::ValidationError => invalid
+  #     puts invalid.model.errors
+  #   end
+  class ValidationError < StandardError
+    attr_reader :model
+
+    def initialize(model)
+      @model = model
+      errors = @model.errors.full_messages.join(", ")
+      super(I18n.t(:"#{@model.class.i18n_scope}.errors.messages.model_invalid", errors: errors, default: :"errors.messages.model_invalid"))
+    end
   end
 end
 
diff --git a/activemodel/lib/active_model/validations/acceptance.rb b/activemodel/lib/active_model/validations/acceptance.rb
index ee160fb483..c5c0cd4636 100644
--- a/activemodel/lib/active_model/validations/acceptance.rb
+++ b/activemodel/lib/active_model/validations/acceptance.rb
@@ -14,16 +14,63 @@ module ActiveModel
       end
 
       private
+
       def setup!(klass)
-        attr_readers = attributes.reject { |name| klass.attribute_method?(name) }
-        attr_writers = attributes.reject { |name| klass.attribute_method?("#{name}=") }
-        klass.send(:attr_reader, *attr_readers)
-        klass.send(:attr_writer, *attr_writers)
+        klass.include(LazilyDefineAttributes.new(AttributeDefinition.new(attributes)))
       end
 
       def acceptable_option?(value)
         Array(options[:accept]).include?(value)
       end
+
+      class LazilyDefineAttributes < Module
+        def initialize(attribute_definition)
+          define_method(:respond_to_missing?) do |method_name, include_private=false|
+            super(method_name, include_private) || attribute_definition.matches?(method_name)
+          end
+
+          define_method(:method_missing) do |method_name, *args, &block|
+            if attribute_definition.matches?(method_name)
+              attribute_definition.define_on(self.class)
+              send(method_name, *args, &block)
+            else
+              super(method_name, *args, &block)
+            end
+          end
+        end
+      end
+
+      class AttributeDefinition
+        def initialize(attributes)
+          @attributes = attributes.map(&:to_s)
+        end
+
+        def matches?(method_name)
+          attr_name = convert_to_reader_name(method_name)
+          attributes.include?(attr_name)
+        end
+
+        def define_on(klass)
+          attr_readers = attributes.reject { |name| klass.attribute_method?(name) }
+          attr_writers = attributes.reject { |name| klass.attribute_method?("#{name}=") }
+          klass.send(:attr_reader, *attr_readers)
+          klass.send(:attr_writer, *attr_writers)
+        end
+
+        protected
+
+        attr_reader :attributes
+
+        private
+
+        def convert_to_reader_name(method_name)
+          attr_name = method_name.to_s
+          if attr_name.end_with?("=")
+            attr_name = attr_name[0..-2]
+          end
+          attr_name
+        end
+      end
     end
 
     module HelperMethods
@@ -42,9 +89,10 @@ module ActiveModel
       # Configuration options:
       # * <tt>:message</tt> - A custom error message (default is: "must be
       #   accepted").
-      # * <tt>:accept</tt> - Specifies value that is considered accepted.
-      #   The default value is a string "1", which makes it easy to relate to
-      #   an HTML checkbox. This should be set to +true+ if you are validating
+      # * <tt>:accept</tt> - Specifies a value that is considered accepted.
+      #   Also accepts an array of possible values. The default value is
+      #   an array ["1", true], which makes it easy to relate to an HTML
+      #   checkbox. This should be set to, or include, +true+ if you are validating
       #   a database column, since the attribute is typecast from "1" to +true+
       #   before validation.
       #
diff --git a/activemodel/lib/active_model/validations/callbacks.rb b/activemodel/lib/active_model/validations/callbacks.rb
index 4b58ef66e3..52111e5442 100644
--- a/activemodel/lib/active_model/validations/callbacks.rb
+++ b/activemodel/lib/active_model/validations/callbacks.rb
@@ -23,6 +23,7 @@ module ActiveModel
       included do
         include ActiveSupport::Callbacks
         define_callbacks :validation,
+                         terminator: deprecated_false_terminator,
                          skip_after_callbacks_if_terminated: true,
                          scope: [:kind, :name]
       end
diff --git a/activemodel/lib/active_model/validations/confirmation.rb b/activemodel/lib/active_model/validations/confirmation.rb
index 1b11c28087..8f8ade90bb 100644
--- a/activemodel/lib/active_model/validations/confirmation.rb
+++ b/activemodel/lib/active_model/validations/confirmation.rb
@@ -3,14 +3,16 @@ module ActiveModel
   module Validations
     class ConfirmationValidator < EachValidator # :nodoc:
       def initialize(options)
-        super
+        super({ case_sensitive: true }.merge!(options))
         setup!(options[:class])
       end
 
       def validate_each(record, attribute, value)
-        if (confirmed = record.send("#{attribute}_confirmation")) && (value != confirmed)
-          human_attribute_name = record.class.human_attribute_name(attribute)
-          record.errors.add(:"#{attribute}_confirmation", :confirmation, options.merge(attribute: human_attribute_name))
+        if (confirmed = record.send("#{attribute}_confirmation"))
+          unless confirmation_value_equal?(record, attribute, value, confirmed)
+            human_attribute_name = record.class.human_attribute_name(attribute)
+            record.errors.add(:"#{attribute}_confirmation", :confirmation, options.except(:case_sensitive).merge!(attribute: human_attribute_name))
+          end
         end
       end
 
@@ -24,6 +26,14 @@ module ActiveModel
           :"#{attribute}_confirmation" unless klass.method_defined?(:"#{attribute}_confirmation=")
         end.compact)
       end
+
+      def confirmation_value_equal?(record, attribute, value, confirmed)
+        if !options[:case_sensitive] && value.is_a?(String)
+          value.casecmp(confirmed) == 0
+        else
+          value == confirmed
+        end
+      end
     end
 
     module HelperMethods
@@ -55,6 +65,8 @@ module ActiveModel
       # Configuration options:
       # * <tt>:message</tt> - A custom error message (default is: "doesn't match
       #   <tt>%{translated_attribute_name}</tt>").
+      # * <tt>:case_sensitive</tt> - Looks for an exact match. Ignored by
+      #   non-text columns (+true+ by default).
       #
       # There is also a list of default options supported by every validator:
       # +:if+, +:unless+, +:on+, +:allow_nil+, +:allow_blank+, and +:strict+.
diff --git a/activemodel/lib/active_model/validations/exclusion.rb b/activemodel/lib/active_model/validations/exclusion.rb
index f342d27275..6f4276cc2a 100644
--- a/activemodel/lib/active_model/validations/exclusion.rb
+++ b/activemodel/lib/active_model/validations/exclusion.rb
@@ -29,7 +29,9 @@ module ActiveModel
       # Configuration options:
       # * <tt>:in</tt> - An enumerable object of items that the value shouldn't
       #   be part of. This can be supplied as a proc, lambda or symbol which returns an
-      #   enumerable. If the enumerable is a range the test is performed with
+      #   enumerable. If the enumerable is a numerical, time or datetime range the test
+      #   is performed with <tt>Range#cover?</tt>, otherwise with <tt>include?</tt>. When
+      #   using a proc or lambda the instance under validation is passed as an argument.
       # * <tt>:within</tt> - A synonym(or alias) for <tt>:in</tt>
       #   <tt>Range#cover?</tt>, otherwise with <tt>include?</tt>.
       # * <tt>:message</tt> - Specifies a custom error message (default is: "is
diff --git a/activemodel/lib/active_model/validations/format.rb b/activemodel/lib/active_model/validations/format.rb
index 02478dd5b6..46a2e54fba 100644
--- a/activemodel/lib/active_model/validations/format.rb
+++ b/activemodel/lib/active_model/validations/format.rb
@@ -77,7 +77,7 @@ module ActiveModel
       #                         with: ->(person) { person.admin? ? /\A[a-z0-9][a-z0-9_\-]*\z/i : /\A[a-z][a-z0-9_\-]*\z/i }
       #   end
       #
-      # Note: use <tt>\A</tt> and <tt>\Z</tt> to match the start and end of the
+      # Note: use <tt>\A</tt> and <tt>\z</tt> to match the start and end of the
       # string, <tt>^</tt> and <tt>$</tt> match the start/end of a line.
       #
       # Due to frequent misuse of <tt>^</tt> and <tt>$</tt>, you need to pass
diff --git a/activemodel/lib/active_model/validations/helper_methods.rb b/activemodel/lib/active_model/validations/helper_methods.rb
new file mode 100644
index 0000000000..2176115334
--- /dev/null
+++ b/activemodel/lib/active_model/validations/helper_methods.rb
@@ -0,0 +1,13 @@
+module ActiveModel
+  module Validations
+    module HelperMethods # :nodoc:
+      private
+        def _merge_attributes(attr_names)
+          options = attr_names.extract_options!.symbolize_keys
+          attr_names.flatten!
+          options[:attributes] = attr_names
+          options
+        end
+    end
+  end
+end
diff --git a/activemodel/lib/active_model/validations/inclusion.rb b/activemodel/lib/active_model/validations/inclusion.rb
index c84025f083..03e0ef56d8 100644
--- a/activemodel/lib/active_model/validations/inclusion.rb
+++ b/activemodel/lib/active_model/validations/inclusion.rb
@@ -28,9 +28,9 @@ module ActiveModel
       # Configuration options:
       # * <tt>:in</tt> - An enumerable object of available items. This can be
       #   supplied as a proc, lambda or symbol which returns an enumerable. If the
-      #   enumerable is a numerical range the test is performed with <tt>Range#cover?</tt>,
-      #   otherwise with <tt>include?</tt>. When using a proc or lambda the instance
-      #   under validation is passed as an argument.
+      #   enumerable is a numerical, time or datetime range the test is performed
+      #   with <tt>Range#cover?</tt>, otherwise with <tt>include?</tt>. When using
+      #   a proc or lambda the instance under validation is passed as an argument.
       # * <tt>:within</tt> - A synonym(or alias) for <tt>:in</tt>
       # * <tt>:message</tt> - Specifies a custom error message (default is: "is
       #   not included in the list").
diff --git a/activemodel/lib/active_model/validations/length.rb b/activemodel/lib/active_model/validations/length.rb
index a96b30cadd..910cca2f49 100644
--- a/activemodel/lib/active_model/validations/length.rb
+++ b/activemodel/lib/active_model/validations/length.rb
@@ -1,6 +1,6 @@
-module ActiveModel
+require "active_support/core_ext/string/strip"
 
-  # == Active \Model Length Validator
+module ActiveModel
   module Validations
     class LengthValidator < EachValidator # :nodoc:
       MESSAGES  = { is: :wrong_length, minimum: :too_short, maximum: :too_long }.freeze
@@ -18,6 +18,27 @@ module ActiveModel
           options[:minimum] = 1
         end
 
+        if options[:tokenizer]
+          ActiveSupport::Deprecation.warn(<<-EOS.strip_heredoc)
+            The `:tokenizer` option is deprecated, and will be removed in Rails 5.1.
+            You can achieve the same functionality by defining an instance method
+            with the value that you want to validate the length of. For example,
+
+                validates_length_of :essay, minimum: 100,
+                  tokenizer: ->(str) { str.scan(/\w+/) }
+
+            should be written as
+
+                validates_length_of :words_in_essay, minimum: 100
+
+                private
+
+                def words_in_essay
+                  essay.scan(/\w+/)
+                end
+          EOS
+        end
+
         super
       end
 
@@ -38,7 +59,7 @@ module ActiveModel
       end
 
       def validate_each(record, attribute, value)
-        value = tokenize(value)
+        value = tokenize(record, value)
         value_length = value.respond_to?(:length) ? value.length : value.to_s.length
         errors_options = options.except(*RESERVED_OPTIONS)
 
@@ -59,10 +80,14 @@ module ActiveModel
       end
 
       private
-
-      def tokenize(value)
-        if options[:tokenizer] && value.kind_of?(String)
-          options[:tokenizer].call(value)
+      def tokenize(record, value)
+        tokenizer = options[:tokenizer]
+        if tokenizer && value.kind_of?(String)
+          if tokenizer.kind_of?(Proc)
+            tokenizer.call(value)
+          elsif record.respond_to?(tokenizer)
+            record.send(tokenizer, value)
+          end
         end || value
       end
 
@@ -73,8 +98,9 @@ module ActiveModel
 
     module HelperMethods
 
-      # Validates that the specified attribute matches the length restrictions
-      # supplied. Only one option can be used at a time:
+      # Validates that the specified attributes match the length restrictions
+      # supplied. Only one constraint option can be used at a time apart from
+      # +:minimum+ and +:maximum+ that can be combined together:
       #
       #   class Person < ActiveRecord::Base
       #     validates_length_of :first_name, maximum: 30
@@ -84,18 +110,27 @@ module ActiveModel
       #     validates_length_of :user_name, within: 6..20, too_long: 'pick a shorter name', too_short: 'pick a longer name'
       #     validates_length_of :zip_code, minimum: 5, too_short: 'please enter at least 5 characters'
       #     validates_length_of :smurf_leader, is: 4, message: "papa is spelled with 4 characters... don't play me."
-      #     validates_length_of :essay, minimum: 100, too_short: 'Your essay must be at least 100 words.',
-      #                         tokenizer: ->(str) { str.scan(/\w+/) }
+      #     validates_length_of :words_in_essay, minimum: 100, too_short: 'Your essay must be at least 100 words.'
+      #
+      #     private
+      #
+      #     def words_in_essay
+      #       essay.scan(/\w+/)
+      #     end
       #   end
       #
-      # Configuration options:
+      # Constraint options:
+      #
       # * <tt>:minimum</tt> - The minimum size of the attribute.
       # * <tt>:maximum</tt> - The maximum size of the attribute. Allows +nil+ by
-      #   default if not used with :minimum.
+      #   default if not used with +:minimum+.
       # * <tt>:is</tt> - The exact size of the attribute.
       # * <tt>:within</tt> - A range specifying the minimum and maximum size of
       #   the attribute.
       # * <tt>:in</tt> - A synonym (or alias) for <tt>:within</tt>.
+      #
+      # Other options:
+      #
       # * <tt>:allow_nil</tt> - Attribute may be +nil+; skip validation.
       # * <tt>:allow_blank</tt> - Attribute may be blank; skip validation.
       # * <tt>:too_long</tt> - The error message if the attribute goes over the
@@ -108,10 +143,6 @@ module ActiveModel
       # * <tt>:message</tt> - The error message to use for a <tt>:minimum</tt>,
       #   <tt>:maximum</tt>, or <tt>:is</tt> violation. An alias of the appropriate
       #   <tt>too_long</tt>/<tt>too_short</tt>/<tt>wrong_length</tt> message.
-      # * <tt>:tokenizer</tt> - Specifies how to split up the attribute string.
-      #   (e.g. <tt>tokenizer: ->(str) { str.scan(/\w+/) }</tt> to count words
-      #   as in above example). Defaults to <tt>->(value) { value.split(//) }</tt>
-      #   which counts individual characters.
       #
       # There is also a list of default options supported by every validator:
       # +:if+, +:unless+, +:on+ and +:strict+.
diff --git a/activemodel/lib/active_model/validations/numericality.rb b/activemodel/lib/active_model/validations/numericality.rb
index 4ba4e3e8f7..9c1e8b4ba7 100644
--- a/activemodel/lib/active_model/validations/numericality.rb
+++ b/activemodel/lib/active_model/validations/numericality.rb
@@ -20,7 +20,7 @@ module ActiveModel
       def validate_each(record, attr_name, value)
         before_type_cast = :"#{attr_name}_before_type_cast"
 
-        raw_value = record.send(before_type_cast) if record.respond_to?(before_type_cast)
+        raw_value = record.send(before_type_cast) if record.respond_to?(before_type_cast) && record.send(before_type_cast) != value
         raw_value ||= value
 
         if record_attribute_changed_in_place?(record, attr_name)
@@ -29,16 +29,14 @@ module ActiveModel
 
         return if options[:allow_nil] && raw_value.nil?
 
-        unless value = parse_raw_value_as_a_number(raw_value)
+        unless is_number?(raw_value)
           record.errors.add(attr_name, :not_a_number, filtered_options(raw_value))
           return
         end
 
-        if allow_only_integer?(record)
-          unless value = parse_raw_value_as_an_integer(raw_value)
-            record.errors.add(attr_name, :not_an_integer, filtered_options(raw_value))
-            return
-          end
+        if allow_only_integer?(record) && !is_integer?(raw_value)
+          record.errors.add(attr_name, :not_an_integer, filtered_options(raw_value))
+          return
         end
 
         options.slice(*CHECKS.keys).each do |option, option_value|
@@ -64,14 +62,15 @@ module ActiveModel
 
     protected
 
-      def parse_raw_value_as_a_number(raw_value)
-        Kernel.Float(raw_value) if raw_value !~ /\A0[xX]/
+      def is_number?(raw_value)
+        parsed_value = Kernel.Float(raw_value) if raw_value !~ /\A0[xX]/
+        !parsed_value.nil?
       rescue ArgumentError, TypeError
-        nil
+        false
       end
 
-      def parse_raw_value_as_an_integer(raw_value)
-        raw_value.to_i if raw_value.to_s =~ /\A[+-]?\d+\z/
+      def is_integer?(raw_value)
+        /\A[+-]?\d+\z/ === raw_value.to_s
       end
 
       def filtered_options(value)
diff --git a/activemodel/lib/active_model/validations/validates.rb b/activemodel/lib/active_model/validations/validates.rb
index bda436d8d0..1da4df21e7 100644
--- a/activemodel/lib/active_model/validations/validates.rb
+++ b/activemodel/lib/active_model/validations/validates.rb
@@ -115,7 +115,7 @@ module ActiveModel
           key = "#{key.to_s.camelize}Validator"
 
           begin
-            validator = key.include?('::') ? key.constantize : const_get(key)
+            validator = key.include?('::'.freeze) ? key.constantize : const_get(key)
           rescue NameError
             raise ArgumentError, "Unknown validator: '#{key}'"
           end
diff --git a/activemodel/lib/active_model/validations/with.rb b/activemodel/lib/active_model/validations/with.rb
index a2531327bf..6de01b3392 100644
--- a/activemodel/lib/active_model/validations/with.rb
+++ b/activemodel/lib/active_model/validations/with.rb
@@ -1,15 +1,5 @@
 module ActiveModel
   module Validations
-    module HelperMethods
-      private
-        def _merge_attributes(attr_names)
-          options = attr_names.extract_options!.symbolize_keys
-          attr_names.flatten!
-          options[:attributes] = attr_names
-          options
-        end
-    end
-
     class WithValidator < EachValidator # :nodoc:
       def validate_each(record, attr, val)
         method_name = options[:with]
diff --git a/activemodel/lib/active_model/validator.rb b/activemodel/lib/active_model/validator.rb
index ac32750946..1d2888a818 100644
--- a/activemodel/lib/active_model/validator.rb
+++ b/activemodel/lib/active_model/validator.rb
@@ -15,7 +15,7 @@ module ActiveModel
   #   class MyValidator < ActiveModel::Validator
   #     def validate(record)
   #       if some_complex_logic
-  #         record.errors[:base] = "This record is invalid"
+  #         record.errors.add(:base, "This record is invalid")
   #       end
   #     end
   #
@@ -163,6 +163,10 @@ module ActiveModel
     # +ArgumentError+ when invalid options are supplied.
     def check_validity!
     end
+
+    def should_validate?(record) # :nodoc:
+      !record.persisted? || record.changed? || record.marked_for_destruction?
+    end
   end
 
   # +BlockValidator+ is a special +EachValidator+ which receives a block on initialization
diff --git a/activemodel/test/cases/attribute_assignment_test.rb b/activemodel/test/cases/attribute_assignment_test.rb
new file mode 100644
index 0000000000..3336691841
--- /dev/null
+++ b/activemodel/test/cases/attribute_assignment_test.rb
@@ -0,0 +1,107 @@
+require "cases/helper"
+require "active_support/hash_with_indifferent_access"
+
+class AttributeAssignmentTest < ActiveModel::TestCase
+  class Model
+    include ActiveModel::AttributeAssignment
+
+    attr_accessor :name, :description
+
+    def initialize(attributes = {})
+      assign_attributes(attributes)
+    end
+
+    def broken_attribute=(value)
+      raise ErrorFromAttributeWriter
+    end
+
+    protected
+
+    attr_writer :metadata
+  end
+
+  class ErrorFromAttributeWriter < StandardError
+  end
+
+  class ProtectedParams < ActiveSupport::HashWithIndifferentAccess
+    def permit!
+      @permitted = true
+    end
+
+    def permitted?
+      @permitted ||= false
+    end
+
+    def dup
+      super.tap do |duplicate|
+        duplicate.instance_variable_set :@permitted, permitted?
+      end
+    end
+  end
+
+  test "simple assignment" do
+    model = Model.new
+
+    model.assign_attributes(name: "hello", description: "world")
+    assert_equal "hello", model.name
+    assert_equal "world", model.description
+  end
+
+  test "assign non-existing attribute" do
+    model = Model.new
+    error = assert_raises(ActiveModel::UnknownAttributeError) do
+      model.assign_attributes(hz: 1)
+    end
+
+    assert_equal model, error.record
+    assert_equal "hz", error.attribute
+  end
+
+  test "assign private attribute" do
+    model = Model.new
+    assert_raises(ActiveModel::UnknownAttributeError) do
+      model.assign_attributes(metadata: { a: 1 })
+    end
+  end
+
+  test "does not swallow errors raised in an attribute writer" do
+    assert_raises(ErrorFromAttributeWriter) do
+      Model.new(broken_attribute: 1)
+    end
+  end
+
+  test "an ArgumentError is raised if a non-hash-like object is passed" do
+    assert_raises(ArgumentError) do
+      Model.new(1)
+    end
+  end
+
+  test "forbidden attributes cannot be used for mass assignment" do
+    params = ProtectedParams.new(name: "Guille", description: "m")
+
+    assert_raises(ActiveModel::ForbiddenAttributesError) do
+      Model.new(params)
+    end
+  end
+
+  test "permitted attributes can be used for mass assignment" do
+    params = ProtectedParams.new(name: "Guille", description: "desc")
+    params.permit!
+    model = Model.new(params)
+
+    assert_equal "Guille", model.name
+    assert_equal "desc", model.description
+  end
+
+  test "regular hash should still be used for mass assignment" do
+    model = Model.new(name: "Guille", description: "m")
+
+    assert_equal "Guille", model.name
+    assert_equal "m", model.description
+  end
+
+  test "assigning no attributes should not raise, even if the hash is un-permitted" do
+    model = Model.new
+    assert_nil model.assign_attributes(ProtectedParams.new({}))
+  end
+end
diff --git a/activemodel/test/cases/dirty_test.rb b/activemodel/test/cases/dirty_test.rb
index 66ed8a350a..d17a12ad12 100644
--- a/activemodel/test/cases/dirty_test.rb
+++ b/activemodel/test/cases/dirty_test.rb
@@ -137,6 +137,19 @@ class DirtyTest < ActiveModel::TestCase
     assert_equal [nil, "Jericho Cane"], @model.previous_changes['name']
   end
 
+  test "setting new attributes should not affect previous changes" do
+    @model.name = "Jericho Cane"
+    @model.save
+    @model.name = "DudeFella ManGuy"
+    assert_equal [nil, "Jericho Cane"], @model.name_previous_change
+  end
+
+  test "saving should preserve model's previous changed status" do
+    @model.name = "Jericho Cane"
+    @model.save
+    assert @model.name_previously_changed?
+  end
+
   test "previous value is preserved when changed after save" do
     assert_equal({}, @model.changed_attributes)
     @model.name = "Paul"
diff --git a/activemodel/test/cases/errors_test.rb b/activemodel/test/cases/errors_test.rb
index efedd9055f..f6d171bec6 100644
--- a/activemodel/test/cases/errors_test.rb
+++ b/activemodel/test/cases/errors_test.rb
@@ -29,28 +29,28 @@ class ErrorsTest < ActiveModel::TestCase
 
   def test_delete
     errors = ActiveModel::Errors.new(self)
-    errors[:foo] = 'omg'
+    errors[:foo] << 'omg'
     errors.delete(:foo)
     assert_empty errors[:foo]
   end
 
   def test_include?
     errors = ActiveModel::Errors.new(self)
-    errors[:foo] = 'omg'
+    errors[:foo] << 'omg'
     assert errors.include?(:foo), 'errors should include :foo'
   end
 
   def test_dup
     errors = ActiveModel::Errors.new(self)
-    errors[:foo] = 'bar'
+    errors[:foo] << 'bar'
     errors_dup = errors.dup
-    errors_dup[:bar] = 'omg'
+    errors_dup[:bar] << 'omg'
     assert_not_same errors_dup.messages, errors.messages
   end
 
   def test_has_key?
     errors = ActiveModel::Errors.new(self)
-    errors[:foo] = 'omg'
+    errors[:foo] << 'omg'
     assert_equal true, errors.has_key?(:foo), 'errors should have key :foo'
   end
 
@@ -61,7 +61,7 @@ class ErrorsTest < ActiveModel::TestCase
 
   def test_key?
     errors = ActiveModel::Errors.new(self)
-    errors[:foo] = 'omg'
+    errors[:foo] << 'omg'
     assert_equal true, errors.key?(:foo), 'errors should have key :foo'
   end
 
@@ -81,37 +81,41 @@ class ErrorsTest < ActiveModel::TestCase
 
   test "get returns the errors for the provided key" do
     errors = ActiveModel::Errors.new(self)
-    errors[:foo] = "omg"
+    errors[:foo] << "omg"
 
-    assert_equal ["omg"], errors.get(:foo)
+    assert_deprecated do
+      assert_equal ["omg"], errors.get(:foo)
+    end
   end
 
   test "sets the error with the provided key" do
     errors = ActiveModel::Errors.new(self)
-    errors.set(:foo, "omg")
+    assert_deprecated do
+      errors.set(:foo, "omg")
+    end
 
     assert_equal({ foo: "omg" }, errors.messages)
   end
 
   test "error access is indifferent" do
     errors = ActiveModel::Errors.new(self)
-    errors[:foo] = "omg"
+    errors[:foo] << "omg"
 
     assert_equal ["omg"], errors["foo"]
   end
 
   test "values returns an array of messages" do
     errors = ActiveModel::Errors.new(self)
-    errors.set(:foo, "omg")
-    errors.set(:baz, "zomg")
+    errors.messages[:foo] = "omg"
+    errors.messages[:baz] = "zomg"
 
     assert_equal ["omg", "zomg"], errors.values
   end
 
   test "keys returns the error keys" do
     errors = ActiveModel::Errors.new(self)
-    errors.set(:foo, "omg")
-    errors.set(:baz, "zomg")
+    errors.messages[:foo] << "omg"
+    errors.messages[:baz] << "zomg"
 
     assert_equal [:foo, :baz], errors.keys
   end
@@ -133,7 +137,9 @@ class ErrorsTest < ActiveModel::TestCase
 
   test "assign error" do
     person = Person.new
-    person.errors[:name] = 'should not be nil'
+    assert_deprecated do
+      person.errors[:name] = 'should not be nil'
+    end
     assert_equal ["should not be nil"], person.errors[:name]
   end
 
@@ -143,6 +149,12 @@ class ErrorsTest < ActiveModel::TestCase
     assert_equal ["cannot be blank"], person.errors[:name]
   end
 
+  test "add an error message on a specific attribute with a defined type" do
+    person = Person.new
+    person.errors.add(:name, :blank, message: "cannot be blank")
+    assert_equal ["cannot be blank"], person.errors[:name]
+  end
+
   test "add an error with a symbol" do
     person = Person.new
     person.errors.add(:name, :blank)
@@ -206,6 +218,12 @@ class ErrorsTest < ActiveModel::TestCase
     assert_equal 1, person.errors.size
   end
 
+  test "count calculates the number of error messages" do
+    person = Person.new
+    person.errors.add(:name, "cannot be blank")
+    assert_equal 1, person.errors.count
+  end
+
   test "to_a returns the list of errors with complete messages containing the attribute names" do
     person = Person.new
     person.errors.add(:name, "cannot be blank")
@@ -281,46 +299,115 @@ class ErrorsTest < ActiveModel::TestCase
 
   test "add_on_empty generates message" do
     person = Person.new
-    person.errors.expects(:generate_message).with(:name, :empty, {})
-    person.errors.add_on_empty :name
+    assert_called_with(person.errors, :generate_message, [:name, :empty, {}]) do
+      assert_deprecated do
+        person.errors.add_on_empty :name
+      end
+    end
   end
 
   test "add_on_empty generates message for multiple attributes" do
     person = Person.new
-    person.errors.expects(:generate_message).with(:name, :empty, {})
-    person.errors.expects(:generate_message).with(:age, :empty, {})
-    person.errors.add_on_empty [:name, :age]
+    expected_calls = [ [:name, :empty, {}], [:age, :empty, {}] ]
+    assert_called_with(person.errors, :generate_message, expected_calls) do
+      assert_deprecated do
+        person.errors.add_on_empty [:name, :age]
+      end
+    end
   end
 
   test "add_on_empty generates message with custom default message" do
     person = Person.new
-    person.errors.expects(:generate_message).with(:name, :empty, { message: 'custom' })
-    person.errors.add_on_empty :name, message: 'custom'
+    assert_called_with(person.errors, :generate_message, [:name, :empty, { message: 'custom' }]) do
+      assert_deprecated do
+        person.errors.add_on_empty :name, message: 'custom'
+      end
+    end
   end
 
   test "add_on_empty generates message with empty string value" do
     person = Person.new
     person.name = ''
-    person.errors.expects(:generate_message).with(:name, :empty, {})
-    person.errors.add_on_empty :name
+    assert_called_with(person.errors, :generate_message, [:name, :empty, {}]) do
+      assert_deprecated do
+        person.errors.add_on_empty :name
+      end
+    end
   end
 
   test "add_on_blank generates message" do
     person = Person.new
-    person.errors.expects(:generate_message).with(:name, :blank, {})
-    person.errors.add_on_blank :name
+    assert_called_with(person.errors, :generate_message, [:name, :blank, {}]) do
+      assert_deprecated do
+        person.errors.add_on_blank :name
+      end
+    end
   end
 
   test "add_on_blank generates message for multiple attributes" do
     person = Person.new
-    person.errors.expects(:generate_message).with(:name, :blank, {})
-    person.errors.expects(:generate_message).with(:age, :blank, {})
-    person.errors.add_on_blank [:name, :age]
+    expected_calls = [ [:name, :blank, {}], [:age, :blank, {}] ]
+    assert_called_with(person.errors, :generate_message, expected_calls) do
+      assert_deprecated do
+        person.errors.add_on_blank [:name, :age]
+      end
+    end
   end
 
   test "add_on_blank generates message with custom default message" do
     person = Person.new
-    person.errors.expects(:generate_message).with(:name, :blank, { message: 'custom' })
-    person.errors.add_on_blank :name, message: 'custom'
+    assert_called_with(person.errors, :generate_message, [:name, :blank, { message: 'custom' }]) do
+      assert_deprecated do
+        person.errors.add_on_blank :name, message: 'custom'
+      end
+    end
+  end
+
+  test "details returns added error detail" do
+    person = Person.new
+    person.errors.add(:name, :invalid)
+    assert_equal({ name: [{ error: :invalid }] }, person.errors.details)
+  end
+
+  test "details returns added error detail with custom option" do
+    person = Person.new
+    person.errors.add(:name, :greater_than, count: 5)
+    assert_equal({ name: [{ error: :greater_than, count: 5 }] }, person.errors.details)
+  end
+
+  test "details do not include message option" do
+    person = Person.new
+    person.errors.add(:name, :invalid, message: "is bad")
+    assert_equal({ name: [{ error: :invalid }] }, person.errors.details)
+  end
+
+  test "dup duplicates details" do
+    errors = ActiveModel::Errors.new(Person.new)
+    errors.add(:name, :invalid)
+    errors_dup = errors.dup
+    errors_dup.add(:name, :taken)
+    assert_not_equal errors_dup.details, errors.details
+  end
+
+  test "delete removes details on given attribute" do
+    errors = ActiveModel::Errors.new(Person.new)
+    errors.add(:name, :invalid)
+    errors.delete(:name)
+    assert_empty errors.details[:name]
+  end
+
+  test "delete returns the deleted messages" do
+    errors = ActiveModel::Errors.new(Person.new)
+    errors.add(:name, :invalid)
+    assert_equal ["is invalid"], errors.delete(:name)
+  end
+
+  test "clear removes details" do
+    person = Person.new
+    person.errors.add(:name, :invalid)
+
+    assert_equal 1, person.errors.details.count
+    person.errors.clear
+    assert person.errors.details.empty?
   end
 end
diff --git a/activemodel/test/cases/helper.rb b/activemodel/test/cases/helper.rb
index 4ce6103593..27fdbc739c 100644
--- a/activemodel/test/cases/helper.rb
+++ b/activemodel/test/cases/helper.rb
@@ -1,6 +1,5 @@
 require File.expand_path('../../../../load_paths', __FILE__)
 
-require 'config'
 require 'active_model'
 require 'active_support/core_ext/string/access'
 
@@ -11,10 +10,17 @@ ActiveSupport::Deprecation.debug = true
 I18n.enforce_available_locales = false
 
 require 'active_support/testing/autorun'
+require 'active_support/testing/method_call_assertions'
 
-require 'mocha/setup' # FIXME: stop using mocha
+# Skips the current run on Rubinius using Minitest::Assertions#skip
+def rubinius_skip(message = '')
+  skip message if RUBY_ENGINE == 'rbx'
+end
+# Skips the current run on JRuby using Minitest::Assertions#skip
+def jruby_skip(message = '')
+  skip message if defined?(JRUBY_VERSION)
+end
 
-# FIXME: we have tests that depend on run order, we should fix that and
-# remove this method call.
-require 'active_support/test_case'
-ActiveSupport::TestCase.test_order = :sorted
+class ActiveModel::TestCase
+  include ActiveSupport::Testing::MethodCallAssertions
+end
diff --git a/activemodel/test/cases/model_test.rb b/activemodel/test/cases/model_test.rb
index ee0fa26546..3017f3541b 100644
--- a/activemodel/test/cases/model_test.rb
+++ b/activemodel/test/cases/model_test.rb
@@ -70,6 +70,8 @@ class ModelTest < ActiveModel::TestCase
   end
 
   def test_mixin_initializer_when_args_dont_exist
-    assert_raises(NoMethodError) { SimpleModel.new(hello: 'world') }
+    assert_raises(ActiveModel::UnknownAttributeError) do
+      SimpleModel.new(hello: 'world')
+    end
   end
 end
diff --git a/activemodel/test/cases/serialization_test.rb b/activemodel/test/cases/serialization_test.rb
index 4ae41aa19c..8d3165cd78 100644
--- a/activemodel/test/cases/serialization_test.rb
+++ b/activemodel/test/cases/serialization_test.rb
@@ -16,6 +16,14 @@ class SerializationTest < ActiveModel::TestCase
       instance_values.except("address", "friends")
     end
 
+    def method_missing(method_name, *args)
+      if method_name == :bar
+        'i_am_bar'
+      else
+        super
+      end
+    end
+
     def foo
       'i_am_foo'
     end
@@ -58,23 +66,22 @@ class SerializationTest < ActiveModel::TestCase
   end
 
   def test_method_serializable_hash_should_work_with_methods_option
-    expected = {"name"=>"David", "gender"=>"male", "foo"=>"i_am_foo", "email"=>"david@example.com"}
-    assert_equal expected, @user.serializable_hash(methods: [:foo])
+    expected = {"name"=>"David", "gender"=>"male", "foo"=>"i_am_foo", "bar"=>"i_am_bar", "email"=>"david@example.com"}
+    assert_equal expected, @user.serializable_hash(methods: [:foo, :bar])
   end
 
   def test_method_serializable_hash_should_work_with_only_and_methods
-    expected = {"foo"=>"i_am_foo"}
-    assert_equal expected, @user.serializable_hash(only: [], methods: [:foo])
+    expected = {"foo"=>"i_am_foo", "bar"=>"i_am_bar"}
+    assert_equal expected, @user.serializable_hash(only: [], methods: [:foo, :bar])
   end
 
   def test_method_serializable_hash_should_work_with_except_and_methods
-    expected = {"gender"=>"male", "foo"=>"i_am_foo"}
-    assert_equal expected, @user.serializable_hash(except: [:name, :email], methods: [:foo])
+    expected = {"gender"=>"male", "foo"=>"i_am_foo", "bar"=>"i_am_bar"}
+    assert_equal expected, @user.serializable_hash(except: [:name, :email], methods: [:foo, :bar])
   end
 
-  def test_should_not_call_methods_that_dont_respond
-    expected = {"name"=>"David", "gender"=>"male", "email"=>"david@example.com"}
-    assert_equal expected, @user.serializable_hash(methods: [:bar])
+  def test_should_raise_NoMethodError_for_non_existing_method
+    assert_raise(NoMethodError) { @user.serializable_hash(methods: [:nada]) }
   end
 
   def test_should_use_read_attribute_for_serialization
diff --git a/activemodel/test/cases/serializers/json_serialization_test.rb b/activemodel/test/cases/serializers/json_serialization_test.rb
index e2eb91eeb0..d765a47636 100644
--- a/activemodel/test/cases/serializers/json_serialization_test.rb
+++ b/activemodel/test/cases/serializers/json_serialization_test.rb
@@ -195,4 +195,8 @@ class JsonSerializationTest < ActiveModel::TestCase
     assert_no_match %r{"awesome":}, json
     assert_no_match %r{"preferences":}, json
   end
+
+  test "Class.model_name should be json encodable" do
+    assert_match %r{"Contact"}, Contact.model_name.to_json
+  end
 end
diff --git a/activemodel/test/cases/serializers/xml_serialization_test.rb b/activemodel/test/cases/serializers/xml_serialization_test.rb
deleted file mode 100644
index 22fca5bd17..0000000000
--- a/activemodel/test/cases/serializers/xml_serialization_test.rb
+++ /dev/null
@@ -1,250 +0,0 @@
-require 'cases/helper'
-require 'models/contact'
-require 'active_support/core_ext/object/instance_variables'
-require 'ostruct'
-
-module Admin
-  class Contact < ::Contact
-  end
-end
-
-class Customer < Struct.new(:name)
-end
-
-class Address
-  include ActiveModel::Serializers::Xml
-
-  attr_accessor :street, :city, :state, :zip, :apt_number
-
-  def attributes
-    instance_values
-  end
-end
-
-class SerializableContact < Contact
-  def serializable_hash(options={})
-    super(options.merge(only: [:name, :age]))
-  end
-end
-
-class XmlSerializationTest < ActiveModel::TestCase
-  def setup
-    @contact = Contact.new
-    @contact.name = 'aaron stack'
-    @contact.age = 25
-    @contact.created_at = Time.utc(2006, 8, 1)
-    @contact.awesome = false
-    customer = Customer.new
-    customer.name = "John"
-    @contact.preferences = customer
-    @contact.address = Address.new
-    @contact.address.city = "Springfield"
-    @contact.address.apt_number = 35
-    @contact.friends = [Contact.new, Contact.new]
-    @contact.contact = SerializableContact.new
-  end
-
-  test "should serialize default root" do
-    xml = @contact.to_xml
-    assert_match %r{^<contact>},  xml
-    assert_match %r{</contact>$}, xml
-  end
-
-  test "should serialize namespaced root" do
-    xml = Admin::Contact.new(@contact.attributes).to_xml
-    assert_match %r{^<contact>},  xml
-    assert_match %r{</contact>$}, xml
-  end
-
-  test "should serialize default root with namespace" do
-    xml = @contact.to_xml namespace: "http://xml.rubyonrails.org/contact"
-    assert_match %r{^<contact xmlns="http://xml.rubyonrails.org/contact">}, xml
-    assert_match %r{</contact>$}, xml
-  end
-
-  test "should serialize custom root" do
-    xml = @contact.to_xml root: 'xml_contact'
-    assert_match %r{^<xml-contact>},  xml
-    assert_match %r{</xml-contact>$}, xml
-  end
-
-  test "should allow undasherized tags" do
-    xml = @contact.to_xml root: 'xml_contact', dasherize: false
-    assert_match %r{^<xml_contact>},  xml
-    assert_match %r{</xml_contact>$}, xml
-    assert_match %r{<created_at},     xml
-  end
-
-  test "should allow camelized tags" do
-    xml = @contact.to_xml root: 'xml_contact', camelize: true
-    assert_match %r{^<XmlContact>},  xml
-    assert_match %r{</XmlContact>$}, xml
-    assert_match %r{<CreatedAt},     xml
-  end
-
-  test "should allow lower-camelized tags" do
-    xml = @contact.to_xml root: 'xml_contact', camelize: :lower
-    assert_match %r{^<xmlContact>},  xml
-    assert_match %r{</xmlContact>$}, xml
-    assert_match %r{<createdAt},     xml
-  end
-
-  test "should use serializable hash" do
-    @contact = SerializableContact.new
-    @contact.name = 'aaron stack'
-    @contact.age = 25
-
-    xml = @contact.to_xml
-    assert_match %r{<name>aaron stack</name>}, xml
-    assert_match %r{<age type="integer">25</age>}, xml
-    assert_no_match %r{<awesome>}, xml
-  end
-
-  test "should allow skipped types" do
-    xml = @contact.to_xml skip_types: true
-    assert_match %r{<age>25</age>}, xml
-  end
-
-  test "should include yielded additions" do
-    xml_output = @contact.to_xml do |xml|
-      xml.creator "David"
-    end
-    assert_match %r{<creator>David</creator>}, xml_output
-  end
-
-  test "should serialize string" do
-    assert_match %r{<name>aaron stack</name>}, @contact.to_xml
-  end
-
-  test "should serialize nil" do
-    assert_match %r{<pseudonyms nil="true"/>}, @contact.to_xml(methods: :pseudonyms)
-  end
-
-  test "should serialize integer" do
-    assert_match %r{<age type="integer">25</age>}, @contact.to_xml
-  end
-
-  test "should serialize datetime" do
-    assert_match %r{<created-at type="dateTime">2006-08-01T00:00:00Z</created-at>}, @contact.to_xml
-  end
-
-  test "should serialize boolean" do
-    assert_match %r{<awesome type="boolean">false</awesome>}, @contact.to_xml
-  end
-
-  test "should serialize array" do
-    assert_match %r{<social type="array">\s*<social>twitter</social>\s*<social>github</social>\s*</social>}, @contact.to_xml(methods: :social)
-  end
-
-  test "should serialize hash" do
-    assert_match %r{<network>\s*<git type="symbol">github</git>\s*</network>}, @contact.to_xml(methods: :network)
-  end
-
-  test "should serialize yaml" do
-    assert_match %r{<preferences type="yaml">--- !ruby/struct:Customer(\s*)\nname: John\n</preferences>}, @contact.to_xml
-  end
-
-  test "should call proc on object" do
-    proc = Proc.new { |options| options[:builder].tag!('nationality', 'unknown') }
-    xml = @contact.to_xml(procs: [ proc ])
-    assert_match %r{<nationality>unknown</nationality>}, xml
-  end
-
-  test "should supply serializable to second proc argument" do
-    proc = Proc.new { |options, record| options[:builder].tag!('name-reverse', record.name.reverse) }
-    xml = @contact.to_xml(procs: [ proc ])
-    assert_match %r{<name-reverse>kcats noraa</name-reverse>}, xml
-  end
-
-  test "should serialize string correctly when type passed" do
-    xml = @contact.to_xml type: 'Contact'
-    assert_match %r{<contact type="Contact">}, xml
-    assert_match %r{<name>aaron stack</name>}, xml
-  end
-
-  test "include option with singular association" do
-    xml = @contact.to_xml include: :address, indent: 0
-    assert xml.include?(@contact.address.to_xml(indent: 0, skip_instruct: true))
-  end
-
-  test "include option with plural association" do
-    xml = @contact.to_xml include: :friends, indent: 0
-    assert_match %r{<friends type="array">}, xml
-    assert_match %r{<friend type="Contact">}, xml
-  end
-
-  class FriendList
-    def initialize(friends)
-      @friends = friends
-    end
-
-    def to_ary
-      @friends
-    end
-  end
-
-  test "include option with ary" do
-    @contact.friends = FriendList.new(@contact.friends)
-    xml = @contact.to_xml include: :friends, indent: 0
-    assert_match %r{<friends type="array">}, xml
-    assert_match %r{<friend type="Contact">}, xml
-  end
-
-  test "multiple includes" do
-    xml = @contact.to_xml indent: 0, skip_instruct: true, include: [ :address, :friends ]
-    assert xml.include?(@contact.address.to_xml(indent: 0, skip_instruct: true))
-    assert_match %r{<friends type="array">}, xml
-    assert_match %r{<friend type="Contact">}, xml
-  end
-
-  test "include with options" do
-    xml = @contact.to_xml indent: 0, skip_instruct: true, include: { address: { only: :city } }
-    assert xml.include?(%(><address><city>Springfield</city></address>))
-  end
-
-  test "propagates skip_types option to included associations" do
-    xml = @contact.to_xml include: :friends, indent: 0, skip_types: true
-    assert_match %r{<friends>}, xml
-    assert_match %r{<friend>}, xml
-  end
-
-  test "propagates skip-types option to included associations and attributes" do
-    xml = @contact.to_xml skip_types: true, include: :address, indent: 0
-    assert_match %r{<address>}, xml
-    assert_match %r{<apt-number>}, xml
-  end
-
-  test "propagates camelize option to included associations and attributes" do
-    xml = @contact.to_xml camelize: true, include: :address, indent: 0
-    assert_match %r{<Address>}, xml
-    assert_match %r{<AptNumber type="integer">}, xml
-  end
-
-  test "propagates dasherize option to included associations and attributes" do
-    xml = @contact.to_xml dasherize: false, include: :address, indent: 0
-    assert_match %r{<apt_number type="integer">}, xml
-  end
-
-  test "don't propagate skip_types if skip_types is defined at the included association level" do
-    xml = @contact.to_xml skip_types: true, include: { address: { skip_types: false } }, indent: 0
-    assert_match %r{<address>}, xml
-    assert_match %r{<apt-number type="integer">}, xml
-  end
-
-  test "don't propagate camelize if camelize is defined at the included association level" do
-    xml = @contact.to_xml camelize: true, include: { address: { camelize: false } }, indent: 0
-    assert_match %r{<address>}, xml
-    assert_match %r{<apt-number type="integer">}, xml
-  end
-
-  test "don't propagate dasherize if dasherize is defined at the included association level" do
-    xml = @contact.to_xml dasherize: false, include: { address: { dasherize: true } }, indent: 0
-    assert_match %r{<address>}, xml
-    assert_match %r{<apt-number type="integer">}, xml
-  end
-
-  test "association with sti" do
-    xml = @contact.to_xml(include: :contact)
-    assert xml.include?(%(<contact type="SerializableContact">))
-  end
-end
diff --git a/activerecord/test/cases/type/decimal_test.rb b/activemodel/test/cases/type/decimal_test.rb
index 34ed1d7b19..353dbf84ad 100644
--- a/activerecord/test/cases/type/decimal_test.rb
+++ b/activemodel/test/cases/type/decimal_test.rb
@@ -1,33 +1,39 @@
 require "cases/helper"
+require "active_model/type"
 
-module ActiveRecord
+module ActiveModel
   module Type
-    class DecimalTest < ActiveRecord::TestCase
+    class DecimalTest < ActiveModel::TestCase
       def test_type_cast_decimal
         type = Decimal.new
-        assert_equal BigDecimal.new("0"), type.type_cast_from_user(BigDecimal.new("0"))
-        assert_equal BigDecimal.new("123"), type.type_cast_from_user(123.0)
-        assert_equal BigDecimal.new("1"), type.type_cast_from_user(:"1")
+        assert_equal BigDecimal.new("0"), type.cast(BigDecimal.new("0"))
+        assert_equal BigDecimal.new("123"), type.cast(123.0)
+        assert_equal BigDecimal.new("1"), type.cast(:"1")
       end
 
       def test_type_cast_decimal_from_float_with_large_precision
         type = Decimal.new(precision: ::Float::DIG + 2)
-        assert_equal BigDecimal.new("123.0"), type.type_cast_from_user(123.0)
+        assert_equal BigDecimal.new("123.0"), type.cast(123.0)
       end
 
       def test_type_cast_from_float_with_unspecified_precision
         type = Decimal.new
-        assert_equal 22.68.to_d, type.type_cast_from_user(22.68)
+        assert_equal 22.68.to_d, type.cast(22.68)
       end
 
       def test_type_cast_decimal_from_rational_with_precision
         type = Decimal.new(precision: 2)
-        assert_equal BigDecimal("0.33"), type.type_cast_from_user(Rational(1, 3))
+        assert_equal BigDecimal("0.33"), type.cast(Rational(1, 3))
+      end
+
+      def test_type_cast_decimal_from_rational_with_precision_and_scale
+        type = Decimal.new(precision: 4, scale: 2)
+        assert_equal BigDecimal("0.33"), type.cast(Rational(1, 3))
       end
 
       def test_type_cast_decimal_from_rational_without_precision_defaults_to_18_36
         type = Decimal.new
-        assert_equal BigDecimal("0.333333333333333333E0"), type.type_cast_from_user(Rational(1, 3))
+        assert_equal BigDecimal("0.333333333333333333E0"), type.cast(Rational(1, 3))
       end
 
       def test_type_cast_decimal_from_object_responding_to_d
@@ -36,7 +42,7 @@ module ActiveRecord
           BigDecimal.new("1")
         end
         type = Decimal.new
-        assert_equal BigDecimal("1"), type.type_cast_from_user(value)
+        assert_equal BigDecimal("1"), type.cast(value)
       end
 
       def test_changed?
diff --git a/activemodel/test/cases/type/integer_test.rb b/activemodel/test/cases/type/integer_test.rb
new file mode 100644
index 0000000000..dac922db42
--- /dev/null
+++ b/activemodel/test/cases/type/integer_test.rb
@@ -0,0 +1,108 @@
+require "cases/helper"
+require "active_model/type"
+
+module ActiveModel
+  module Type
+    class IntegerTest < ActiveModel::TestCase
+      test "simple values" do
+        type = Type::Integer.new
+        assert_equal 1, type.cast(1)
+        assert_equal 1, type.cast('1')
+        assert_equal 1, type.cast('1ignore')
+        assert_equal 0, type.cast('bad1')
+        assert_equal 0, type.cast('bad')
+        assert_equal 1, type.cast(1.7)
+        assert_equal 0, type.cast(false)
+        assert_equal 1, type.cast(true)
+        assert_nil type.cast(nil)
+      end
+
+      test "random objects cast to nil" do
+        type = Type::Integer.new
+        assert_nil type.cast([1,2])
+        assert_nil type.cast({1 => 2})
+        assert_nil type.cast(1..2)
+      end
+
+      test "casting objects without to_i" do
+        type = Type::Integer.new
+        assert_nil type.cast(::Object.new)
+      end
+
+      test "casting nan and infinity" do
+        type = Type::Integer.new
+        assert_nil type.cast(::Float::NAN)
+        assert_nil type.cast(1.0/0.0)
+      end
+
+      test "casting booleans for database" do
+        type = Type::Integer.new
+        assert_equal 1, type.serialize(true)
+        assert_equal 0, type.serialize(false)
+      end
+
+      test "changed?" do
+        type = Type::Integer.new
+
+        assert type.changed?(5, 5, '5wibble')
+        assert_not type.changed?(5, 5, '5')
+        assert_not type.changed?(5, 5, '5.0')
+        assert_not type.changed?(-5, -5, '-5')
+        assert_not type.changed?(-5, -5, '-5.0')
+        assert_not type.changed?(nil, nil, nil)
+      end
+
+      test "values below int min value are out of range" do
+        assert_raises(::RangeError) do
+          Integer.new.serialize(-2147483649)
+        end
+      end
+
+      test "values above int max value are out of range" do
+        assert_raises(::RangeError) do
+          Integer.new.serialize(2147483648)
+        end
+      end
+
+      test "very small numbers are out of range" do
+        assert_raises(::RangeError) do
+          Integer.new.serialize(-9999999999999999999999999999999)
+        end
+      end
+
+      test "very large numbers are out of range" do
+        assert_raises(::RangeError) do
+          Integer.new.serialize(9999999999999999999999999999999)
+        end
+      end
+
+      test "normal numbers are in range" do
+        type = Integer.new
+        assert_equal(0, type.serialize(0))
+        assert_equal(-1, type.serialize(-1))
+        assert_equal(1, type.serialize(1))
+      end
+
+      test "int max value is in range" do
+        assert_equal(2147483647, Integer.new.serialize(2147483647))
+      end
+
+      test "int min value is in range" do
+        assert_equal(-2147483648, Integer.new.serialize(-2147483648))
+      end
+
+      test "columns with a larger limit have larger ranges" do
+        type = Integer.new(limit: 8)
+
+        assert_equal(9223372036854775807, type.serialize(9223372036854775807))
+        assert_equal(-9223372036854775808, type.serialize(-9223372036854775808))
+        assert_raises(::RangeError) do
+          type.serialize(-9999999999999999999999999999999)
+        end
+        assert_raises(::RangeError) do
+          type.serialize(9999999999999999999999999999999)
+        end
+      end
+    end
+  end
+end
diff --git a/activemodel/test/cases/type/registry_test.rb b/activemodel/test/cases/type/registry_test.rb
new file mode 100644
index 0000000000..2a48998a62
--- /dev/null
+++ b/activemodel/test/cases/type/registry_test.rb
@@ -0,0 +1,39 @@
+require "cases/helper"
+require "active_model/type"
+
+module ActiveModel
+  class RegistryTest < ActiveModel::TestCase
+    test "a class can be registered for a symbol" do
+      registry = Type::Registry.new
+      registry.register(:foo, ::String)
+      registry.register(:bar, ::Array)
+
+      assert_equal "", registry.lookup(:foo)
+      assert_equal [], registry.lookup(:bar)
+    end
+
+    test "a block can be registered" do
+      registry = Type::Registry.new
+      registry.register(:foo) do |*args|
+        [*args, "block for foo"]
+      end
+      registry.register(:bar) do |*args|
+        [*args, "block for bar"]
+      end
+
+      assert_equal [:foo, 1, "block for foo"], registry.lookup(:foo, 1)
+      assert_equal [:foo, 2, "block for foo"], registry.lookup(:foo, 2)
+      assert_equal [:bar, 1, 2, 3, "block for bar"], registry.lookup(:bar, 1, 2, 3)
+    end
+
+    test "a reasonable error is given when no type is found" do
+      registry = Type::Registry.new
+
+      e = assert_raises(ArgumentError) do
+        registry.lookup(:foo)
+      end
+
+      assert_equal "Unknown type :foo", e.message
+    end
+  end
+end
diff --git a/activemodel/test/cases/type/string_test.rb b/activemodel/test/cases/type/string_test.rb
new file mode 100644
index 0000000000..7b25a1ef74
--- /dev/null
+++ b/activemodel/test/cases/type/string_test.rb
@@ -0,0 +1,27 @@
+require "cases/helper"
+require "active_model/type"
+
+module ActiveModel
+  class StringTypeTest < ActiveModel::TestCase
+    test "type casting" do
+      type = Type::String.new
+      assert_equal "t", type.cast(true)
+      assert_equal "f", type.cast(false)
+      assert_equal "123", type.cast(123)
+    end
+
+    test "immutable strings are not duped coming out" do
+      s = "foo"
+      type = Type::ImmutableString.new
+      assert_same s, type.cast(s)
+      assert_same s, type.deserialize(s)
+    end
+
+    test "values are duped coming out" do
+      s = "foo"
+      type = Type::String.new
+      assert_not_same s, type.cast(s)
+      assert_not_same s, type.deserialize(s)
+    end
+  end
+end
diff --git a/activerecord/test/cases/type/unsigned_integer_test.rb b/activemodel/test/cases/type/unsigned_integer_test.rb
index b6f673109e..16301b3ac0 100644
--- a/activerecord/test/cases/type/unsigned_integer_test.rb
+++ b/activemodel/test/cases/type/unsigned_integer_test.rb
@@ -1,15 +1,16 @@
 require "cases/helper"
+require "active_model/type"
 
-module ActiveRecord
+module ActiveModel
   module Type
-    class UnsignedIntegerTest < ActiveRecord::TestCase
+    class UnsignedIntegerTest < ActiveModel::TestCase
       test "unsigned int max value is in range" do
-        assert_equal(4294967295, UnsignedInteger.new.type_cast_from_user("4294967295"))
+        assert_equal(4294967295, UnsignedInteger.new.serialize(4294967295))
       end
 
       test "minus value is out of range" do
         assert_raises(::RangeError) do
-          UnsignedInteger.new.type_cast_from_user("-1")
+          UnsignedInteger.new.serialize(-1)
         end
       end
     end
diff --git a/activemodel/test/cases/types_test.rb b/activemodel/test/cases/types_test.rb
new file mode 100644
index 0000000000..f937208580
--- /dev/null
+++ b/activemodel/test/cases/types_test.rb
@@ -0,0 +1,122 @@
+require "cases/helper"
+require "active_model/type"
+require "active_support/core_ext/numeric/time"
+
+module ActiveModel
+  class TypesTest < ActiveModel::TestCase
+    def test_type_cast_boolean
+      type = Type::Boolean.new
+      assert type.cast('').nil?
+      assert type.cast(nil).nil?
+
+      assert type.cast(true)
+      assert type.cast(1)
+      assert type.cast('1')
+      assert type.cast('t')
+      assert type.cast('T')
+      assert type.cast('true')
+      assert type.cast('TRUE')
+      assert type.cast('on')
+      assert type.cast('ON')
+      assert type.cast(' ')
+      assert type.cast("\u3000\r\n")
+      assert type.cast("\u0000")
+      assert type.cast('SOMETHING RANDOM')
+
+      # explicitly check for false vs nil
+      assert_equal false, type.cast(false)
+      assert_equal false, type.cast(0)
+      assert_equal false, type.cast('0')
+      assert_equal false, type.cast('f')
+      assert_equal false, type.cast('F')
+      assert_equal false, type.cast('false')
+      assert_equal false, type.cast('FALSE')
+      assert_equal false, type.cast('off')
+      assert_equal false, type.cast('OFF')
+    end
+
+    def test_type_cast_float
+      type = Type::Float.new
+      assert_equal 1.0, type.cast("1")
+    end
+
+    def test_changing_float
+      type = Type::Float.new
+
+      assert type.changed?(5.0, 5.0, '5wibble')
+      assert_not type.changed?(5.0, 5.0, '5')
+      assert_not type.changed?(5.0, 5.0, '5.0')
+      assert_not type.changed?(nil, nil, nil)
+    end
+
+    def test_type_cast_binary
+      type = Type::Binary.new
+      assert_equal nil, type.cast(nil)
+      assert_equal "1", type.cast("1")
+      assert_equal 1, type.cast(1)
+    end
+
+    def test_type_cast_time
+      type = Type::Time.new
+      assert_equal nil, type.cast(nil)
+      assert_equal nil, type.cast('')
+      assert_equal nil, type.cast('ABC')
+
+      time_string = Time.now.utc.strftime("%T")
+      assert_equal time_string, type.cast(time_string).strftime("%T")
+    end
+
+    def test_type_cast_datetime_and_timestamp
+      type = Type::DateTime.new
+      assert_equal nil, type.cast(nil)
+      assert_equal nil, type.cast('')
+      assert_equal nil, type.cast('  ')
+      assert_equal nil, type.cast('ABC')
+
+      datetime_string = Time.now.utc.strftime("%FT%T")
+      assert_equal datetime_string, type.cast(datetime_string).strftime("%FT%T")
+    end
+
+    def test_type_cast_date
+      type = Type::Date.new
+      assert_equal nil, type.cast(nil)
+      assert_equal nil, type.cast('')
+      assert_equal nil, type.cast(' ')
+      assert_equal nil, type.cast('ABC')
+
+      date_string = Time.now.utc.strftime("%F")
+      assert_equal date_string, type.cast(date_string).strftime("%F")
+    end
+
+    def test_type_cast_duration_to_integer
+      type = Type::Integer.new
+      assert_equal 1800, type.cast(30.minutes)
+      assert_equal 7200, type.cast(2.hours)
+    end
+
+    def test_string_to_time_with_timezone
+      ["UTC", "US/Eastern"].each do |zone|
+        with_timezone_config default: zone do
+          type = Type::DateTime.new
+          assert_equal Time.utc(2013, 9, 4, 0, 0, 0), type.cast("Wed, 04 Sep 2013 03:00:00 EAT")
+        end
+      end
+    end
+
+    def test_type_equality
+      assert_equal Type::Value.new, Type::Value.new
+      assert_not_equal Type::Value.new, Type::Integer.new
+      assert_not_equal Type::Value.new(precision: 1), Type::Value.new(precision: 2)
+    end
+
+    private
+
+    def with_timezone_config(default:)
+      old_zone_default = ::Time.zone_default
+      ::Time.zone_default = ::Time.find_zone(default)
+      yield
+    ensure
+      ::Time.zone_default = old_zone_default
+    end
+  end
+end
diff --git a/activemodel/test/cases/validations/absence_validation_test.rb b/activemodel/test/cases/validations/absence_validation_test.rb
index ebfe1cf4e4..9cbc77dfb5 100644
--- a/activemodel/test/cases/validations/absence_validation_test.rb
+++ b/activemodel/test/cases/validations/absence_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'models/topic'
 require 'models/person'
diff --git a/activemodel/test/cases/validations/acceptance_validation_test.rb b/activemodel/test/cases/validations/acceptance_validation_test.rb
index b7872ea6bf..d3995ad5af 100644
--- a/activemodel/test/cases/validations/acceptance_validation_test.rb
+++ b/activemodel/test/cases/validations/acceptance_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
@@ -51,6 +50,20 @@ class AcceptanceValidationTest < ActiveModel::TestCase
     assert t.valid?
   end
 
+  def test_terms_of_service_agreement_with_multiple_accept_values
+    Topic.validates_acceptance_of(:terms_of_service, accept: [1, "I concur."])
+
+    t = Topic.new("title" => "We should be confirmed", "terms_of_service" => "")
+    assert t.invalid?
+    assert_equal ["must be accepted"], t.errors[:terms_of_service]
+
+    t.terms_of_service = 1
+    assert t.valid?
+
+    t.terms_of_service = "I concur."
+    assert t.valid?
+  end
+
   def test_validates_acceptance_of_for_ruby_class
     Person.validates_acceptance_of :karma
 
diff --git a/activemodel/test/cases/validations/callbacks_test.rb b/activemodel/test/cases/validations/callbacks_test.rb
index cc50ffbbef..75eb18e795 100644
--- a/activemodel/test/cases/validations/callbacks_test.rb
+++ b/activemodel/test/cases/validations/callbacks_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 class Dog
diff --git a/activemodel/test/cases/validations/conditional_validation_test.rb b/activemodel/test/cases/validations/conditional_validation_test.rb
index 1261937b56..296d3b4407 100644
--- a/activemodel/test/cases/validations/conditional_validation_test.rb
+++ b/activemodel/test/cases/validations/conditional_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/confirmation_validation_test.rb b/activemodel/test/cases/validations/confirmation_validation_test.rb
index 65a2a1eb49..c56bf1c0ad 100644
--- a/activemodel/test/cases/validations/confirmation_validation_test.rb
+++ b/activemodel/test/cases/validations/confirmation_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
@@ -105,4 +104,18 @@ class ConfirmationValidationTest < ActiveModel::TestCase
     assert_equal "expected title", model.title_confirmation,
      "confirmation validation should not override the writer"
   end
+
+  def test_title_confirmation_with_case_sensitive_option_true
+    Topic.validates_confirmation_of(:title, case_sensitive: true)
+
+    t = Topic.new(title: "title", title_confirmation: "Title")
+    assert t.invalid?
+  end
+
+  def test_title_confirmation_with_case_sensitive_option_false
+    Topic.validates_confirmation_of(:title, case_sensitive: false)
+
+    t = Topic.new(title: "title", title_confirmation: "Title")
+    assert t.valid?
+  end
 end
diff --git a/activemodel/test/cases/validations/exclusion_validation_test.rb b/activemodel/test/cases/validations/exclusion_validation_test.rb
index 1ce41f9bc9..005bc15df5 100644
--- a/activemodel/test/cases/validations/exclusion_validation_test.rb
+++ b/activemodel/test/cases/validations/exclusion_validation_test.rb
@@ -1,5 +1,5 @@
-# encoding: utf-8
 require 'cases/helper'
+require 'active_support/core_ext/numeric/time'
 
 require 'models/topic'
 require 'models/person'
@@ -65,6 +65,22 @@ class ExclusionValidationTest < ActiveModel::TestCase
     assert t.valid?
   end
 
+  def test_validates_exclusion_of_with_range
+    Topic.validates_exclusion_of :content, in: ("a".."g")
+
+    assert Topic.new(content: 'g').invalid?
+    assert Topic.new(content: 'h').valid?
+  end
+
+  def test_validates_exclusion_of_with_time_range
+    Topic.validates_exclusion_of :created_at, in: 6.days.ago..2.days.ago
+
+    assert Topic.new(created_at: 5.days.ago).invalid?
+    assert Topic.new(created_at: 3.days.ago).invalid?
+    assert Topic.new(created_at: 7.days.ago).valid?
+    assert Topic.new(created_at: 1.day.ago).valid?
+  end
+
   def test_validates_inclusion_of_with_symbol
     Person.validates_exclusion_of :karma, in: :reserved_karmas
 
diff --git a/activemodel/test/cases/validations/format_validation_test.rb b/activemodel/test/cases/validations/format_validation_test.rb
index 0f91b73cd7..86bbbe6ebe 100644
--- a/activemodel/test/cases/validations/format_validation_test.rb
+++ b/activemodel/test/cases/validations/format_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/i18n_generate_message_validation_test.rb b/activemodel/test/cases/validations/i18n_generate_message_validation_test.rb
index 3eeb80a48b..da63df9152 100644
--- a/activemodel/test/cases/validations/i18n_generate_message_validation_test.rb
+++ b/activemodel/test/cases/validations/i18n_generate_message_validation_test.rb
@@ -62,7 +62,7 @@ class I18nGenerateMessageValidationTest < ActiveModel::TestCase
     assert_equal 'custom message', @person.errors.generate_message(:title, :empty, message: 'custom message')
   end
 
-  # add_on_blank: generate_message(attr, :blank, message: custom_message)
+  # validates_presence_of: generate_message(attr, :blank, message: custom_message)
   def test_generate_message_blank_with_default_message
     assert_equal "can't be blank", @person.errors.generate_message(:title, :blank)
   end
diff --git a/activemodel/test/cases/validations/i18n_validation_test.rb b/activemodel/test/cases/validations/i18n_validation_test.rb
index 96084a32ba..09d7226b5a 100644
--- a/activemodel/test/cases/validations/i18n_validation_test.rb
+++ b/activemodel/test/cases/validations/i18n_validation_test.rb
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 require "cases/helper"
 require 'models/person'
 
@@ -32,8 +30,9 @@ class I18nValidationTest < ActiveModel::TestCase
 
   def test_errors_full_messages_translates_human_attribute_name_for_model_attributes
     @person.errors.add(:name, 'not found')
-    Person.expects(:human_attribute_name).with(:name, default: 'Name').returns("Person's name")
-    assert_equal ["Person's name not found"], @person.errors.full_messages
+    assert_called_with(Person, :human_attribute_name, [:name, default: 'Name'], returns: "Person's name") do
+      assert_equal ["Person's name not found"], @person.errors.full_messages
+    end
   end
 
   def test_errors_full_messages_uses_format
@@ -56,176 +55,175 @@ class I18nValidationTest < ActiveModel::TestCase
     [ "given option that is not reserved", { format: "jpg" },             { format: "jpg" }]
   ]
 
-  # validates_confirmation_of w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_confirmation_of on generated message #{name}" do
       Person.validates_confirmation_of :title, validation_options
       @person.title_confirmation = 'foo'
-      @person.errors.expects(:generate_message).with(:title_confirmation, :confirmation, generate_message_options.merge(attribute: 'Title'))
-      @person.valid?
+      call = [:title_confirmation, :confirmation, generate_message_options.merge(attribute: 'Title')]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_acceptance_of w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_acceptance_of on generated message #{name}" do
       Person.validates_acceptance_of :title, validation_options.merge(allow_nil: false)
-      @person.errors.expects(:generate_message).with(:title, :accepted, generate_message_options)
-      @person.valid?
+      call = [:title, :accepted, generate_message_options]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_presence_of w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_presence_of on generated message #{name}" do
       Person.validates_presence_of :title, validation_options
-      @person.errors.expects(:generate_message).with(:title, :blank, generate_message_options)
-      @person.valid?
+      call = [:title, :blank, generate_message_options]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_length_of :within too short w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
-    test "validates_length_of for :withing on generated message when too short #{name}" do
+    test "validates_length_of for :within on generated message when too short #{name}" do
       Person.validates_length_of :title, validation_options.merge(within: 3..5)
-      @person.errors.expects(:generate_message).with(:title, :too_short, generate_message_options.merge(count: 3))
-      @person.valid?
+      call = [:title, :too_short, generate_message_options.merge(count: 3)]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_length_of :within too long w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_length_of for :too_long generated message #{name}" do
       Person.validates_length_of :title, validation_options.merge(within: 3..5)
       @person.title = 'this title is too long'
-      @person.errors.expects(:generate_message).with(:title, :too_long, generate_message_options.merge(count: 5))
-      @person.valid?
+      call = [:title, :too_long, generate_message_options.merge(count: 5)]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_length_of :is w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_length_of for :is on generated message #{name}" do
       Person.validates_length_of :title, validation_options.merge(is: 5)
-      @person.errors.expects(:generate_message).with(:title, :wrong_length, generate_message_options.merge(count: 5))
-      @person.valid?
+      call = [:title, :wrong_length, generate_message_options.merge(count: 5)]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_format_of w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_format_of on generated message #{name}" do
       Person.validates_format_of :title, validation_options.merge(with: /\A[1-9][0-9]*\z/)
       @person.title = '72x'
-      @person.errors.expects(:generate_message).with(:title, :invalid, generate_message_options.merge(value: '72x'))
-      @person.valid?
+      call = [:title, :invalid, generate_message_options.merge(value: '72x')]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_inclusion_of w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_inclusion_of on generated message #{name}" do
       Person.validates_inclusion_of :title, validation_options.merge(in: %w(a b c))
       @person.title = 'z'
-      @person.errors.expects(:generate_message).with(:title, :inclusion, generate_message_options.merge(value: 'z'))
-      @person.valid?
+      call = [:title, :inclusion, generate_message_options.merge(value: 'z')]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_inclusion_of using :within w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_inclusion_of using :within on generated message #{name}" do
       Person.validates_inclusion_of :title, validation_options.merge(within: %w(a b c))
       @person.title = 'z'
-      @person.errors.expects(:generate_message).with(:title, :inclusion, generate_message_options.merge(value: 'z'))
-      @person.valid?
+      call = [:title, :inclusion, generate_message_options.merge(value: 'z')]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_exclusion_of w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_exclusion_of generated message #{name}" do
       Person.validates_exclusion_of :title, validation_options.merge(in: %w(a b c))
       @person.title = 'a'
-      @person.errors.expects(:generate_message).with(:title, :exclusion, generate_message_options.merge(value: 'a'))
-      @person.valid?
+      call = [:title, :exclusion, generate_message_options.merge(value: 'a')]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_exclusion_of using :within w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_exclusion_of using :within generated message #{name}" do
       Person.validates_exclusion_of :title, validation_options.merge(within: %w(a b c))
       @person.title = 'a'
-      @person.errors.expects(:generate_message).with(:title, :exclusion, generate_message_options.merge(value: 'a'))
-      @person.valid?
+      call = [:title, :exclusion, generate_message_options.merge(value: 'a')]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_numericality_of without :only_integer w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_numericality_of generated message #{name}" do
       Person.validates_numericality_of :title, validation_options
       @person.title = 'a'
-      @person.errors.expects(:generate_message).with(:title, :not_a_number, generate_message_options.merge(value: 'a'))
-      @person.valid?
+      call = [:title, :not_a_number, generate_message_options.merge(value: 'a')]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_numericality_of with :only_integer w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_numericality_of for :only_integer on generated message #{name}" do
       Person.validates_numericality_of :title, validation_options.merge(only_integer: true)
       @person.title = '0.0'
-      @person.errors.expects(:generate_message).with(:title, :not_an_integer, generate_message_options.merge(value: '0.0'))
-      @person.valid?
+      call = [:title, :not_an_integer, generate_message_options.merge(value: '0.0')]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_numericality_of :odd w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_numericality_of for :odd on generated message #{name}" do
       Person.validates_numericality_of :title, validation_options.merge(only_integer: true, odd: true)
       @person.title = 0
-      @person.errors.expects(:generate_message).with(:title, :odd, generate_message_options.merge(value: 0))
-      @person.valid?
+      call = [:title, :odd, generate_message_options.merge(value: 0)]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-  # validates_numericality_of :less_than w/ mocha
-
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_numericality_of for :less_than on generated message #{name}" do
       Person.validates_numericality_of :title, validation_options.merge(only_integer: true, less_than: 0)
       @person.title = 1
-      @person.errors.expects(:generate_message).with(:title, :less_than, generate_message_options.merge(value: 1, count: 0))
-      @person.valid?
+      call = [:title, :less_than, generate_message_options.merge(value: 1, count: 0)]
+      assert_called_with(@person.errors, :generate_message, call) do
+        @person.valid?
+      end
     end
   end
 
-
-  # To make things DRY this macro is defined to define 3 tests for every validation case.
+  # To make things DRY this macro is created to define 3 tests for every validation case.
   def self.set_expectations_for_validation(validation, error_type, &block_that_sets_validation)
     if error_type == :confirmation
       attribute = :title_confirmation
     else
       attribute = :title
     end
-    # test "validates_confirmation_of finds custom model key translation when blank"
+
     test "#{validation} finds custom model key translation when #{error_type}" do
       I18n.backend.store_translations 'en', activemodel: { errors: { models: { person: { attributes: { attribute => { error_type => 'custom message' } } } } } }
       I18n.backend.store_translations 'en', errors: { messages: { error_type => 'global message'}}
@@ -235,7 +233,6 @@ class I18nValidationTest < ActiveModel::TestCase
       assert_equal ['custom message'], @person.errors[attribute]
     end
 
-    # test "validates_confirmation_of finds custom model key translation with interpolation when blank"
     test "#{validation} finds custom model key translation with interpolation when #{error_type}" do
       I18n.backend.store_translations 'en', activemodel: { errors: { models: { person: { attributes: { attribute => { error_type => 'custom message with %{extra}' } } } } } }
       I18n.backend.store_translations 'en', errors: { messages: {error_type => 'global message'} }
@@ -245,7 +242,6 @@ class I18nValidationTest < ActiveModel::TestCase
       assert_equal ['custom message with extra information'], @person.errors[attribute]
     end
 
-    # test "validates_confirmation_of finds global default key translation when blank"
     test "#{validation} finds global default key translation when #{error_type}" do
       I18n.backend.store_translations 'en', errors: { messages: {error_type => 'global message'} }
 
@@ -255,27 +251,19 @@ class I18nValidationTest < ActiveModel::TestCase
     end
   end
 
-  # validates_confirmation_of w/o mocha
-
   set_expectations_for_validation "validates_confirmation_of", :confirmation do |person, options_to_merge|
     Person.validates_confirmation_of :title, options_to_merge
     person.title_confirmation = 'foo'
   end
 
-  # validates_acceptance_of w/o mocha
-
   set_expectations_for_validation "validates_acceptance_of", :accepted do |person, options_to_merge|
     Person.validates_acceptance_of :title, options_to_merge.merge(allow_nil: false)
   end
 
-  # validates_presence_of w/o mocha
-
   set_expectations_for_validation "validates_presence_of", :blank do |person, options_to_merge|
     Person.validates_presence_of :title, options_to_merge
   end
 
-  # validates_length_of :within w/o mocha
-
   set_expectations_for_validation "validates_length_of", :too_short do |person, options_to_merge|
     Person.validates_length_of :title, options_to_merge.merge(within: 3..5)
   end
@@ -285,61 +273,43 @@ class I18nValidationTest < ActiveModel::TestCase
     person.title = "too long"
   end
 
-  # validates_length_of :is w/o mocha
-
   set_expectations_for_validation "validates_length_of", :wrong_length do |person, options_to_merge|
     Person.validates_length_of :title, options_to_merge.merge(is: 5)
   end
 
-  # validates_format_of w/o mocha
-
   set_expectations_for_validation "validates_format_of", :invalid do |person, options_to_merge|
     Person.validates_format_of :title, options_to_merge.merge(with: /\A[1-9][0-9]*\z/)
   end
 
-  # validates_inclusion_of w/o mocha
-
   set_expectations_for_validation "validates_inclusion_of", :inclusion do |person, options_to_merge|
     Person.validates_inclusion_of :title, options_to_merge.merge(in: %w(a b c))
   end
 
-  # validates_exclusion_of w/o mocha
-
   set_expectations_for_validation "validates_exclusion_of", :exclusion do |person, options_to_merge|
     Person.validates_exclusion_of :title, options_to_merge.merge(in: %w(a b c))
     person.title = 'a'
   end
 
-  # validates_numericality_of without :only_integer w/o mocha
-
   set_expectations_for_validation "validates_numericality_of", :not_a_number do |person, options_to_merge|
     Person.validates_numericality_of :title, options_to_merge
     person.title = 'a'
   end
 
-  # validates_numericality_of with :only_integer w/o mocha
-
   set_expectations_for_validation "validates_numericality_of", :not_an_integer do |person, options_to_merge|
     Person.validates_numericality_of :title, options_to_merge.merge(only_integer: true)
     person.title = '1.0'
   end
 
-  # validates_numericality_of :odd w/o mocha
-
   set_expectations_for_validation "validates_numericality_of", :odd do |person, options_to_merge|
     Person.validates_numericality_of :title, options_to_merge.merge(only_integer: true, odd: true)
     person.title = 0
   end
 
-  # validates_numericality_of :less_than w/o mocha
-
   set_expectations_for_validation "validates_numericality_of", :less_than do |person, options_to_merge|
     Person.validates_numericality_of :title, options_to_merge.merge(only_integer: true, less_than: 0)
     person.title = 1
   end
 
-  # test with validates_with
-
   def test_validations_with_message_symbol_must_translate
     I18n.backend.store_translations 'en', errors: { messages: { custom_error: "I am a custom error" } }
     Person.validates_presence_of :title, message: :custom_error
diff --git a/activemodel/test/cases/validations/inclusion_validation_test.rb b/activemodel/test/cases/validations/inclusion_validation_test.rb
index 3a8f3080e1..55d1fb4dcb 100644
--- a/activemodel/test/cases/validations/inclusion_validation_test.rb
+++ b/activemodel/test/cases/validations/inclusion_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'active_support/all'
 
diff --git a/activemodel/test/cases/validations/length_validation_test.rb b/activemodel/test/cases/validations/length_validation_test.rb
index 046ffcb16f..ee901b75fb 100644
--- a/activemodel/test/cases/validations/length_validation_test.rb
+++ b/activemodel/test/cases/validations/length_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
@@ -320,8 +319,33 @@ class LengthValidationTest < ActiveModel::TestCase
   end
 
   def test_validates_length_of_with_block
-    Topic.validates_length_of :content, minimum: 5, too_short: "Your essay must be at least %{count} words.",
-                                        tokenizer: lambda {|str| str.scan(/\w+/) }
+    assert_deprecated do
+      Topic.validates_length_of(
+        :content,
+        minimum: 5,
+        too_short: "Your essay must be at least %{count} words.",
+        tokenizer: lambda {|str| str.scan(/\w+/) },
+      )
+    end
+    t = Topic.new(content: "this content should be long enough")
+    assert t.valid?
+
+    t.content = "not long enough"
+    assert t.invalid?
+    assert t.errors[:content].any?
+    assert_equal ["Your essay must be at least 5 words."], t.errors[:content]
+  end
+
+
+  def test_validates_length_of_with_symbol
+    assert_deprecated do
+      Topic.validates_length_of(
+        :content,
+        minimum: 5,
+        too_short: "Your essay must be at least %{count} words.",
+        tokenizer: :my_word_tokenizer,
+      )
+    end
     t = Topic.new(content: "this content should be long enough")
     assert t.valid?
 
diff --git a/activemodel/test/cases/validations/numericality_validation_test.rb b/activemodel/test/cases/validations/numericality_validation_test.rb
index 12a22f9c40..04ec74bad3 100644
--- a/activemodel/test/cases/validations/numericality_validation_test.rb
+++ b/activemodel/test/cases/validations/numericality_validation_test.rb
@@ -1,10 +1,10 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
 require 'models/person'
 
 require 'bigdecimal'
+require 'active_support/core_ext/big_decimal'
 
 class NumericalityValidationTest < ActiveModel::TestCase
 
@@ -72,6 +72,13 @@ class NumericalityValidationTest < ActiveModel::TestCase
     valid!([11])
   end
 
+  def test_validates_numericality_with_greater_than_using_differing_numeric_types
+    Topic.validates_numericality_of :approved, greater_than: BigDecimal.new('97.18')
+
+    invalid!([-97.18, BigDecimal.new('97.18'), BigDecimal('-97.18')], 'must be greater than 97.18')
+    valid!([97.18, 98, BigDecimal.new('98')]) # Notice the 97.18 as a float is greater than 97.18 as a BigDecimal due to floating point precision
+  end
+
   def test_validates_numericality_with_greater_than_or_equal
     Topic.validates_numericality_of :approved, greater_than_or_equal_to: 10
 
@@ -79,6 +86,13 @@ class NumericalityValidationTest < ActiveModel::TestCase
     valid!([10])
   end
 
+  def test_validates_numericality_with_greater_than_or_equal_using_differing_numeric_types
+    Topic.validates_numericality_of :approved, greater_than_or_equal_to: BigDecimal.new('97.18') 
+
+    invalid!([-97.18, 97.17, 97, BigDecimal.new('97.17'), BigDecimal.new('-97.18')], 'must be greater than or equal to 97.18')
+    valid!([97.18, 98, BigDecimal.new('97.19')])
+  end
+
   def test_validates_numericality_with_equal_to
     Topic.validates_numericality_of :approved, equal_to: 10
 
@@ -86,6 +100,13 @@ class NumericalityValidationTest < ActiveModel::TestCase
     valid!([10])
   end
 
+  def test_validates_numericality_with_equal_to_using_differing_numeric_types
+    Topic.validates_numericality_of :approved, equal_to: BigDecimal.new('97.18')
+
+    invalid!([-97.18, 97.18], 'must be equal to 97.18')
+    valid!([BigDecimal.new('97.18')])
+  end
+
   def test_validates_numericality_with_less_than
     Topic.validates_numericality_of :approved, less_than: 10
 
@@ -93,6 +114,13 @@ class NumericalityValidationTest < ActiveModel::TestCase
     valid!([-9, 9])
   end
 
+  def test_validates_numericality_with_less_than_using_differing_numeric_types
+    Topic.validates_numericality_of :approved, less_than: BigDecimal.new('97.18')
+
+    invalid!([97.18, BigDecimal.new('97.18')], 'must be less than 97.18')
+    valid!([-97.0, 97.0, -97, 97, BigDecimal.new('-97'), BigDecimal.new('97')])
+  end
+
   def test_validates_numericality_with_less_than_or_equal_to
     Topic.validates_numericality_of :approved, less_than_or_equal_to: 10
 
@@ -100,6 +128,13 @@ class NumericalityValidationTest < ActiveModel::TestCase
     valid!([-10, 10])
   end
 
+  def test_validates_numericality_with_less_than_or_equal_to_using_differing_numeric_types
+    Topic.validates_numericality_of :approved, less_than_or_equal_to: BigDecimal.new('97.18')
+
+    invalid!([97.18, 98], 'must be less than or equal to 97.18')
+    valid!([-97.18, BigDecimal.new('-97.18'), BigDecimal.new('97.18')])
+  end
+
   def test_validates_numericality_with_odd
     Topic.validates_numericality_of :approved, odd: true
 
@@ -197,7 +232,7 @@ class NumericalityValidationTest < ActiveModel::TestCase
 
   def valid!(values)
     with_each_topic_approved_value(values) do |topic, value|
-      assert topic.valid?, "#{value.inspect} not accepted as a number"
+      assert topic.valid?, "#{value.inspect} not accepted as a number with validation error: #{topic.errors[:approved].first}"
     end
   end
 
diff --git a/activemodel/test/cases/validations/presence_validation_test.rb b/activemodel/test/cases/validations/presence_validation_test.rb
index ecf16d1e16..59b9db0795 100644
--- a/activemodel/test/cases/validations/presence_validation_test.rb
+++ b/activemodel/test/cases/validations/presence_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/validates_test.rb b/activemodel/test/cases/validations/validates_test.rb
index 8d4b74ee49..04101f3545 100644
--- a/activemodel/test/cases/validations/validates_test.rb
+++ b/activemodel/test/cases/validations/validates_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'models/person'
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/validations_context_test.rb b/activemodel/test/cases/validations/validations_context_test.rb
index 005bf118c6..b901a1523e 100644
--- a/activemodel/test/cases/validations/validations_context_test.rb
+++ b/activemodel/test/cases/validations/validations_context_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
@@ -9,6 +8,7 @@ class ValidationsContextTest < ActiveModel::TestCase
   end
 
   ERROR_MESSAGE = "Validation error from validator"
+  ANOTHER_ERROR_MESSAGE = "Another validation error from validator"
 
   class ValidatorThatAddsErrors < ActiveModel::Validator
     def validate(record)
@@ -16,6 +16,12 @@ class ValidationsContextTest < ActiveModel::TestCase
     end
   end
 
+  class AnotherValidatorThatAddsErrors < ActiveModel::Validator
+    def validate(record)
+      record.errors[:base] << ANOTHER_ERROR_MESSAGE
+    end
+  end
+
   test "with a class that adds errors on create and validating a new model with no arguments" do
     Topic.validates_with(ValidatorThatAddsErrors, on: :create)
     topic = Topic.new
@@ -47,4 +53,16 @@ class ValidationsContextTest < ActiveModel::TestCase
     assert topic.invalid?(:context2), "Validation did not run on context2 when 'on' is set to context1 and context2"
     assert topic.errors[:base].include?(ERROR_MESSAGE)
   end
+
+  test "with a class that validating a model for a multiple contexts" do
+    Topic.validates_with(ValidatorThatAddsErrors, on: :context1)
+    Topic.validates_with(AnotherValidatorThatAddsErrors, on: :context2)
+
+    topic = Topic.new
+    assert topic.valid?, "Validation ran with no context given when 'on' is set to context1 and context2"
+
+    assert topic.invalid?([:context1, :context2]), "Validation did not run on context1 when 'on' is set to context1 and context2"
+    assert topic.errors[:base].include?(ERROR_MESSAGE)
+    assert topic.errors[:base].include?(ANOTHER_ERROR_MESSAGE)
+  end
 end
diff --git a/activemodel/test/cases/validations/with_validation_test.rb b/activemodel/test/cases/validations/with_validation_test.rb
index 736c2deea8..03c7943308 100644
--- a/activemodel/test/cases/validations/with_validation_test.rb
+++ b/activemodel/test/cases/validations/with_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
@@ -98,12 +97,14 @@ class ValidatesWithTest < ActiveModel::TestCase
 
   test "passes all configuration options to the validator class" do
     topic = Topic.new
-    validator = mock()
-    validator.expects(:new).with(foo: :bar, if: "1 == 1", class: Topic).returns(validator)
-    validator.expects(:validate).with(topic)
+    validator = Minitest::Mock.new
+    validator.expect(:new, validator, [{foo: :bar, if: "1 == 1", class: Topic}])
+    validator.expect(:validate, nil, [topic])
+    validator.expect(:is_a?, false, [Symbol])
 
     Topic.validates_with(validator, if: "1 == 1", foo: :bar)
     assert topic.valid?
+    validator.verify
   end
 
   test "validates_with with options" do
diff --git a/activemodel/test/cases/validations_test.rb b/activemodel/test/cases/validations_test.rb
index 2b932683ea..f0317ad219 100644
--- a/activemodel/test/cases/validations_test.rb
+++ b/activemodel/test/cases/validations_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
@@ -352,6 +351,25 @@ class ValidationsTest < ActiveModel::TestCase
     assert_not_empty topic.errors
   end
 
+  def test_validate_with_bang
+    Topic.validates :title, presence: true
+
+    assert_raise(ActiveModel::ValidationError) do
+      Topic.new.validate!
+    end
+  end
+
+  def test_validate_with_bang_and_context
+    Topic.validates :title, presence: true, on: :context
+
+    assert_raise(ActiveModel::ValidationError) do
+      Topic.new.validate!(:context)
+    end
+
+    t = Topic.new(title: "Valid title")
+    assert t.validate!(:context)
+  end
+
   def test_strict_validation_in_validates
     Topic.validates :title, strict: true, presence: true
     assert_raises ActiveModel::StrictValidationFailed do
diff --git a/activemodel/test/config.rb b/activemodel/test/config.rb
deleted file mode 100644
index 0b577a9936..0000000000
--- a/activemodel/test/config.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-TEST_ROOT       = File.expand_path(File.dirname(__FILE__))
-FIXTURES_ROOT   = TEST_ROOT + "/fixtures"
-SCHEMA_FILE     = TEST_ROOT + "/schema.rb"
diff --git a/activemodel/test/models/contact.rb b/activemodel/test/models/contact.rb
index bcfd267a34..113ab0bc1f 100644
--- a/activemodel/test/models/contact.rb
+++ b/activemodel/test/models/contact.rb
@@ -4,7 +4,6 @@ class Contact
   include ActiveModel::Validations
 
   include ActiveModel::Serializers::JSON
-  include ActiveModel::Serializers::Xml
 
   attr_accessor :id, :name, :age, :created_at, :awesome, :preferences
   attr_accessor :address, :friends, :contact
diff --git a/activemodel/test/models/topic.rb b/activemodel/test/models/topic.rb
index 1411a093e9..fed50bc361 100644
--- a/activemodel/test/models/topic.rb
+++ b/activemodel/test/models/topic.rb
@@ -37,4 +37,8 @@ class Topic
     errors.add attr, "is missing" unless send(attr)
   end
 
+  def my_word_tokenizer(str)
+   str.scan(/\w+/)
+  end
+
 end
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index d0dcff801b..86738fa819 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -14,9 +14,1127 @@
 
     *Seb Jacobs*
 
-*   `time` columns can now affected by `time_zone_aware_attributes`. If you have
+*   Includes HABTM returns correct size now. It's caused by the join dependency
+    only instantiates one HABTM object because the join table hasn't a primary key.
+
+    Fixes #16032.
+
+    Examples:
+
+        before:
+
+        Project.first.salaried_developers.size # => 3
+        Project.includes(:salaried_developers).first.salaried_developers.size # => 1
+
+        after:
+
+        Project.first.salaried_developers.size # => 3
+        Project.includes(:salaried_developers).first.salaried_developers.size # => 3
+
+    *Bigxiang*
+
+*   Add option to index errors in nested attributes
+
+    For models which have nested attributes, errors within those models will
+    now be indexed if :index_errors is specified when defining a
+    has_many relationship, or if its set in the global config.
+
+    Example:
+
+        class Guitar < ActiveRecord::Base
+          has_many :tuning_pegs
+          accepts_nested_attributes_for :tuning_pegs
+        end
+
+        class TuningPeg < ActiveRecord::Base
+          belongs_to :guitar
+          validates_numericality_of :pitch
+        end
+
+     - Old style
+     - `guitar.errors["tuning_pegs.pitch"] = ["is not a number"]`
+
+     - New style (if defined globally, or set in has_many_relationship)
+     - `guitar.errors["tuning_pegs[1].pitch"] = ["is not a number"]`
+
+    *Michael Probber and Terence Sun*
+
+*   Exit with non-zero status for failed database rake tasks.
+
+    *Jay Hayes*
+
+*   Queries such as `Computer.joins(:monitor).group(:status).count` will now be
+    interpreted as  `Computer.joins(:monitor).group('computers.status').count`
+    so that when `Computer` and `Monitor` have both `status` columns we don't
+    have conflicts in projection.
+
+    *Rafael Sales*
+
+*   Add ability to default to `uuid` as primary key when generating database migrations
+
+    config.generators do |g|
+      g.orm :active_record, primary_key_type: :uuid
+    end
+
+    *Jon McCartie*
+
+*   Don't cache arguments in #find_by if they are an ActiveRecord::Relation
+
+    Fixes #20817
+
+    *Hiroaki Izu*
+
+*   Qualify column name inserted by `group` in calculation
+
+    Giving `group` an unqualified column name now works, even if the relation
+    has `JOIN` with another table which also has a column of the name.
+
+    *Soutaro Matsumoto*
+
+*   Don't cache prepared statements containing an IN clause or a SQL literal, as
+    these queries will change often and are unlikely to have a cache hit.
+
+    *Sean Griffin*
+
+*   Fix `rewhere` in a `has_many` association.
+
+    Fixes #21955.
+
+    *Josh Branchaud*, *Kal*
+
+*   `where` raises ArgumentError on unsupported types.
+
+    Fixes #20473.
+
+    *Jake Worth*
+
+*   Add an immutable string type to help reduce memory usage for apps which do
+    not need mutation detection on Strings.
+
+    *Sean Griffin*
+
+*   Give `AcriveRecord::Relation#update` its own deprecation warning when
+    passed an `ActiveRecord::Base` instance.
+
+    Fixes #21945.
+
+    *Ted Johansson*
+
+*   Make it possible to pass `:to_table` when adding a foreign key through
+    `add_reference`.
+
+    Fixes #21563.
+
+    *Yves Senn*
+
+*   No longer pass depreacted option `-i` to `pg_dump`.
+
+    *Paul Sadauskas*
+
+*   Concurrent `AR::Base#increment!` and `#decrement!` on the same record
+    are all reflected in the database rather than overwriting each other.
+
+    *Bogdan Gusiev*
+
+*   Avoid leaking the first relation we call `first` on, per model.
+
+    Fixes #21921.
+
+    *Matthew Draper*, *Jean Boussier*
+
+*   Remove unused `pk_and_sequence_for` in AbstractMysqlAdapter.
+
+    *Ryuta Kamizono*
+
+*   Allow fixtures files to set the model class in the YAML file itself.
+
+    To load the fixtures file `accounts.yml` as the `User` model, use:
+
+          _fixture:
+            model_class: User
+          david:
+            name: David
+
+    Fixes #9516.
+
+    *Roque Pinel*
+
+*   Don't require a database connection to load a class which uses acceptance
+    validations.
+
+    *Sean Griffin*
+
+*   Correctly apply `unscope` when preloading through associations.
+
+    *Jimmy Bourassa*
+
+*   Fixed taking precision into count when assigning a value to timestamp attribute
+
+    Timestamp column can have less precision than ruby timestamp
+    In result in how big a fraction of a second can be stored in the
+    database.
+
+
+        m = Model.create!
+        m.created_at.usec == m.reload.created_at.usec # => false
+        # due to different precision in Time.now and database column
+
+    If the precision is low enough, (mysql default is 0, so it is always low
+    enough by default) the value changes when model is reloaded from the
+    database. This patch fixes that issue ensuring that any timestamp
+    assigned as an attribute is converted to column precision under the
+    attribute.
+
+    *Bogdan Gusiev*
+
+*   Introduce `connection.data_sources` and `connection.data_source_exists?`.
+    These methods determine what relations can be used to back Active Record
+    models (usually tables and views).
+
+    Also deprecate `SchemaCache#tables`, `SchemaCache#table_exists?` and
+    `SchemaCache#clear_table_cache!` in favor of their new data source
+    counterparts.
+
+    *Yves Senn*, *Matthew Draper*
+
+*   Add `ActiveRecord::Base.ignored_columns` to make some columns
+    invisible from ActiveRecord.
+
+    *Jean Boussier*
+
+*   `ActiveRecord::Tasks::MySQLDatabaseTasks` fails if shellout to
+    mysql commands (like `mysqldump`) is not successful.
+
+    *Steve Mitchell*
+
+*   Ensure `select` quotes aliased attributes, even when using `from`.
+
+    Fixes #21488
+
+    *Sean Griffin & @johanlunds*
+
+*   MySQL: support `unsigned` numeric data types.
+
+    Example:
+
+        create_table :foos do |t|
+          t.unsigned_integer :quantity
+          t.unsigned_bigint  :total
+          t.unsigned_float   :percentage
+          t.unsigned_decimal :price, precision: 10, scale: 2
+        end
+
+    The `unsigned: true` option may be used for the primary key:
+
+        create_table :foos, id: :bigint, unsigned: true do |t|
+          …
+        end
+
+    *Ryuta Kamizono*
+
+*   Add `#views` and `#view_exists?` methods on connection adapters.
+
+    *Ryuta Kamizono*
+
+*   Correctly dump composite primary key.
+
+    Example:
+
+        create_table :barcodes, primary_key: ["region", "code"] do |t|
+          t.string :region
+          t.integer :code
+        end
+
+    *Ryuta Kamizono*
+
+*   Lookup the attribute name for `restrict_with_error` messages on the
+    model class that defines the association.
+
+    *kuboon*, *Ronak Jangir*
+
+*   Correct query for PostgreSQL 8.2 compatibility.
+
+    *Ben Murphy*, *Matthew Draper*
+
+*   `bin/rake db:migrate` uses
+    `ActiveRecord::Tasks::DatabaseTasks.migrations_paths` instead of
+    `Migrator.migrations_paths`.
+
+    *Tobias Bielohlawek*
+
+*   Support dropping indexes concurrently in PostgreSQL.
+
+    See http://www.postgresql.org/docs/9.4/static/sql-dropindex.html for more
+    details.
+
+    *Grey Baker*
+
+*   Deprecate passing conditions to `ActiveRecord::Relation#delete_all`
+    and `ActiveRecord::Relation#destroy_all`.
+
+    *Wojciech Wnętrzak*
+
+*   PostgreSQL, `create_schema`, `drop_schema` and `rename_table` now quote
+    schema names.
+
+    Fixes #21418.
+
+    Example:
+
+        create_schema("my.schema")
+        # CREATE SCHEMA "my.schema";
+
+    *Yves Senn*
+
+*   PostgreSQL, add `:if_exists` option to `#drop_schema`. This makes it
+    possible to drop a schema that might exist without raising an exception if
+    it doesn't.
+
+    *Yves Senn*
+
+*   Only try to nullify has_one target association if the record is persisted.
+
+    Fixes #21223.
+
+    *Agis Anastasopoulos*
+
+*   Uniqueness validator raises descriptive error when running on a persisted
+    record without primary key.
+
+    Fixes #21304.
+
+    *Yves Senn*
+
+*   Add a native JSON data type support in MySQL.
+
+    Example:
+
+        create_table :json_data_type do |t|
+          t.json :settings
+        end
+
+    *Ryuta Kamizono*
+
+*   Descriptive error message when fixtures contain a missing column.
+
+    Fixes #21201.
+
+    *Yves Senn*
+
+*   `ActiveRecord::Tasks::PostgreSQLDatabaseTasks` fail if shellout to
+    postgresql commands (like `pg_dump`) is not successful.
+
+    *Bryan Paxton*, *Nate Berkopec*
+
+*   Add `ActiveRecord::Relation#in_batches` to work with records and relations
+    in batches.
+
+    Available options are `of` (batch size), `load`, `begin_at`, and `end_at`.
+
+    Examples:
+
+        Person.in_batches.each_record(&:party_all_night!)
+        Person.in_batches.update_all(awesome: true)
+        Person.in_batches.delete_all
+        Person.in_batches.each do |relation|
+          relation.delete_all
+          sleep 10 # Throttles the delete queries
+        end
+
+    Fixes #20933.
+
+    *Sina Siadat*
+
+*   Added methods for PostgreSQL geometric data types to use in migrations.
+
+    Example:
+
+        create_table :foo do |t|
+          t.line :foo_line
+          t.lseg :foo_lseg
+          t.box :foo_box
+          t.path :foo_path
+          t.polygon :foo_polygon
+          t.circle :foo_circle
+        end
+
+    *Mehmet Emin İNAÇ*
+
+*   Add `cache_key` to ActiveRecord::Relation.
+
+    Example:
+
+        @users = User.where("name like ?", "%Alberto%")
+        @users.cache_key
+        # => "/users/query-5942b155a43b139f2471b872ac54251f-3-20150714212107656125000"
+
+    *Alberto Fernández-Capel*
+
+*   Properly allow uniqueness validations on primary keys.
+
+    Fixes #20966.
+
+    *Sean Griffin*, *presskey*
+
+*   Don't raise an error if an association failed to destroy when `destroy` was
+    called on the parent (as opposed to `destroy!`).
+
+    Fixes #20991.
+
+    *Sean Griffin*
+
+*   `ActiveRecord::RecordNotFound` modified to store model name, primary_key and
+    id of the caller model. It allows the catcher of this exception to make
+    a better decision to what to do with it.
+
+    Example:
+
+        class SomeAbstractController < ActionController::Base
+          rescue_from ActiveRecord::RecordNotFound, with: :redirect_to_404
+
+          private def redirect_to_404(e)
+            return redirect_to(posts_url) if e.model == 'Post'
+            raise
+          end
+        end
+
+    *Sameer Rahmani*
+
+*   Deprecate the keys for association `restrict_dependent_destroy` errors in favor
+    of new key names.
+
+    Previously `has_one` and `has_many` associations were using the
+    `one` and `many` keys respectively. Both of these keys have special
+    meaning in I18n (they are considered to be pluralizations) so by
+    renaming them to `has_one` and `has_many` we make the messages more explicit
+    and most importantly they don't clash with linguistical systems that need to
+    validate translation keys (and their pluralizations).
+
+    The `:'restrict_dependent_destroy.one'` key should be replaced with
+    `:'restrict_dependent_destroy.has_one'`, and `:'restrict_dependent_destroy.many'`
+    with `:'restrict_dependent_destroy.has_many'`.
+
+    *Roque Pinel*, *Christopher Dell*
+
+*   Fix state being carried over from previous transaction.
+
+    Considering the following example where `name` is a required attribute.
+    Before we had `new_record?` returning `true` for a persisted record:
+
+        author = Author.create! name: 'foo'
+        author.name = nil
+        author.save        # => false
+        author.new_record? # => true
+
+    Fixes #20824.
+
+    *Roque Pinel*
+
+*   Correctly ignore `mark_for_destruction` when `autosave` isn't set to `true`
+    when validating associations.
+
+    Fixes #20882.
+
+    *Sean Griffin*
+
+*   Fix a bug where counter_cache doesn't always work with polymorphic
+    relations.
+
+    Fixes #16407.
+
+    *Stefan Kanev*, *Sean Griffin*
+
+*   Ensure that cyclic associations with autosave don't cause duplicate errors
+    to be added to the parent record.
+
+    Fixes #20874.
+
+    *Sean Griffin*
+
+*   Ensure that `ActionController::Parameters` can still be passed to nested
+    attributes.
+
+    Fixes #20922.
+
+    *Sean Griffin*
+
+*   Deprecate force association reload by passing a truthy argument to
+    association method.
+
+    For collection association, you can call `#reload` on association proxy to
+    force a reload:
+
+        @user.posts.reload   # Instead of @user.posts(true)
+
+    For singular association, you can call `#reload` on the parent object to
+    clear its association cache then call the association method:
+
+        @user.reload.profile   # Instead of @user.profile(true)
+
+    Passing a truthy argument to force association to reload will be removed in
+    Rails 5.1.
+
+    *Prem Sichanugrist*
+
+*   Replaced `ActiveSupport::Concurrency::Latch` with `Concurrent::CountDownLatch`
+    from the concurrent-ruby gem.
+
+    *Jerry D'Antonio*
+
+*   Fix through associations using scopes having the scope merged multiple
+    times.
+
+    Fixes #20721.
+    Fixes #20727.
+
+    *Sean Griffin*
+
+*   `ActiveRecord::Base.dump_schema_after_migration` applies migration tasks
+    other than `db:migrate`. (eg. `db:rollback`, `db:migrate:dup`, ...)
+
+    Fixes #20743.
+
+    *Yves Senn*
+
+*   Add alternate syntax to make `change_column_default` reversible.
+
+    User can pass in `:from` and `:to` to make `change_column_default` command
+    become reversible.
+
+    Example:
+
+        change_column_default :posts, :status, from: nil, to: "draft"
+        change_column_default :users, :authorized, from: true, to: false
+
+    *Prem Sichanugrist*
+
+*   Prevent error when using `force_reload: true` on an unassigned polymorphic
+    belongs_to association.
+
+    Fixes #20426.
+
+    *James Dabbs*
+
+*   Correctly raise `ActiveRecord::AssociationTypeMismatch` when assigning
+    a wrong type to a namespaced association.
+
+    Fixes #20545.
+
+    *Diego Carrion*
+
+*   `validates_absence_of` respects `marked_for_destruction?`.
+
+    Fixes #20449.
+
+    *Yves Senn*
+
+*   Include the `Enumerable` module in `ActiveRecord::Relation`
+
+    *Sean Griffin & bogdan*
+
+*   Use `Enumerable#sum` in `ActiveRecord::Relation` if a block is given.
+
+    *Sean Griffin*
+
+*   Let `WITH` queries (Common Table Expressions) be explainable.
+
+    *Vladimir Kochnev*
+
+*   Make `remove_index :table, :column` reversible.
+
+    *Yves Senn*
+
+*   Fixed an error which would occur in dirty checking when calling
+    `update_attributes` from a getter.
+
+    Fixes #20531.
+
+    *Sean Griffin*
+
+*   Make `remove_foreign_key` reversible. Any foreign key options must be
+    specified, similar to `remove_column`.
+
+    *Aster Ryan*
+
+*   Add `:_prefix` and `:_suffix` options to `enum` definition.
+
+    Fixes #17511, #17415.
+
+    *Igor Kapkov*
+
+*   Correctly handle decimal arrays with defaults in the schema dumper.
+
+    Fixes #20515.
+
+    *Sean Griffin & jmondo*
+
+*   Deprecate the PostgreSQL `:point` type in favor of a new one which will return
+    `Point` objects instead of an `Array`
+
+    *Sean Griffin*
+
+*   Ensure symbols passed to `ActiveRecord::Relation#select` are always treated
+    as columns.
+
+    Fixes #20360.
+
+    *Sean Griffin*
+
+*   Do not set `sql_mode` if `strict: :default` is specified.
+
+        # config/database.yml
+        production:
+          adapter: mysql2
+          database: foo_prod
+          user: foo
+          strict: :default
+
+    *Ryuta Kamizono*
+
+*   Allow proc defaults to be passed to the attributes API. See documentation
+    for examples.
+
+    *Sean Griffin*, *Kir Shatrov*
+
+*   SQLite: `:collation` support for string and text columns.
+
+    Example:
+
+        create_table :foo do |t|
+          t.string :string_nocase, collation: 'NOCASE'
+          t.text :text_rtrim, collation: 'RTRIM'
+        end
+
+        add_column :foo, :title, :string, collation: 'RTRIM'
+
+        change_column :foo, :title, :string, collation: 'NOCASE'
+
+    *Akshay Vishnoi*
+
+*   Allow the use of symbols or strings to specify enum values in test
+    fixtures:
+
+        awdr:
+          title: "Agile Web Development with Rails"
+          status: :proposed
+
+    *George Claghorn*
+
+*   Clear query cache when `ActiveRecord::Base#reload` is called.
+
+    *Shane Hender, Pierre Nespo*
+
+*   Include stored procedures and function on the MySQL structure dump.
+
+    *Jonathan Worek*
+
+*   Pass `:extend` option for `has_and_belongs_to_many` associations to the
+    underlying `has_many :through`.
+
+    *Jaehyun Shin*
+
+*   Deprecate `Relation#uniq` use `Relation#distinct` instead.
+
+    See #9683.
+
+    *Yves Senn*
+
+*   Allow single table inheritance instantiation to work when storing
+    demodulized class names.
+
+    *Alex Robbin*
+
+*   Correctly pass MySQL options when using `structure_dump` or
+    `structure_load`.
+
+    Specifically, it fixes an issue when using SSL authentication.
+
+    *Alex Coomans*
+
+*   Dump indexes in `create_table` instead of `add_index`.
+
+    If the adapter supports indexes in `create_table`, generated SQL is
+    slightly more efficient.
+
+    *Ryuta Kamizono*
+
+*   Correctly dump `:options` on `create_table` for MySQL.
+
+    *Ryuta Kamizono*
+
+*   PostgreSQL: `:collation` support for string and text columns.
+
+    Example:
+
+        create_table :foos do |t|
+          t.string :string_en, collation: 'en_US.UTF-8'
+          t.text   :text_ja,   collation: 'ja_JP.UTF-8'
+        end
+
+    *Ryuta Kamizono*
+
+*   Remove `ActiveRecord::Serialization::XmlSerializer` from core.
+
+    *Zachary Scott*
+
+*   Make `unscope` aware of "less than" and "greater than" conditions.
+
+    *TAKAHASHI Kazuaki*
+
+*   `find_by` and `find_by!` raise `ArgumentError` when called without
+    arguments.
+
+    *Kohei Suzuki*
+
+*   Revert behavior of `db:schema:load` back to loading the full
+    environment. This ensures that initializers are run.
+
+    Fixes #19545.
+
+    *Yves Senn*
+
+*   Fix missing index when using `timestamps` with the `index` option.
+
+    The `index` option used with `timestamps` should be passed to both
+    `column` definitions for `created_at` and `updated_at` rather than just
+    the first.
+
+    *Paul Mucur*
+
+*   Rename `:class` to `:anonymous_class` in association options.
+
+    Fixes #19659.
+
+    *Andrew White*
+
+*   Autosave existing records on a has many through association when the parent
+    is new.
+
+    Fixes #19782.
+
+    *Sean Griffin*
+
+*   Fixed a bug where uniqueness validations would error on out of range values,
+    even if an validation should have prevented it from hitting the database.
+
+    *Andrey Voronkov*
+
+*   MySQL: `:charset` and `:collation` support for string and text columns.
+
+    Example:
+
+        create_table :foos do |t|
+          t.string :string_utf8_bin, charset: 'utf8', collation: 'utf8_bin'
+          t.text   :text_ascii,      charset: 'ascii'
+        end
+
+    *Ryuta Kamizono*
+
+*   Foreign key related methods in the migration DSL respect
+    `ActiveRecord::Base.pluralize_table_names = false`.
+
+    Fixes #19643.
+
+    *Mehmet Emin İNAÇ*
+
+*   Reduce memory usage from loading types on PostgreSQL.
+
+    Fixes #19578.
+
+    *Sean Griffin*
+
+*   Add `config.active_record.warn_on_records_fetched_greater_than` option.
+
+    When set to an integer, a warning will be logged whenever a result set
+    larger than the specified size is returned by a query.
+
+    Fixes #16463.
+
+    *Jason Nochlin*
+
+*   Ignore `.psqlrc` when loading database structure.
+
+    *Jason Weathered*
+
+*   Fix referencing wrong table aliases while joining tables of has many through
+    association (only when calling calculation methods).
+
+    Fixes #19276.
+
+    *pinglamb*
+
+*   Correctly persist a serialized attribute that has been returned to
+    its default value by an in-place modification.
+
+    Fixes #19467.
+
+    *Matthew Draper*
+
+*   Fix generating the schema file when using PostgreSQL `BigInt[]` data type.
+    Previously the `limit: 8` was not coming through, and this caused it to
+    become `Int[]` data type after rebuilding from the schema.
+
+    Fixes #19420.
+
+    *Jake Waller*
+
+*   Reuse the `CollectionAssociation#reader` cache when the foreign key is
+    available prior to save.
+
+    *Ben Woosley*
+
+*   Add `config.active_record.dump_schemas` to fix `db:structure:dump`
+    when using schema_search_path and PostgreSQL extensions.
+
+    Fixes #17157.
+
+    *Ryan Wallace*
+
+*   Renaming `use_transactional_fixtures` to `use_transactional_tests` for clarity.
+
+    Fixes #18864.
+
+    *Brandon Weiss*
+
+*   Increase pg gem version requirement to `~> 0.18`. Earlier versions of the
+    pg gem are known to have problems with Ruby 2.2.
+
+    *Matt Brictson*
+
+*   Correctly dump `serial` and `bigserial`.
+
+    *Ryuta Kamizono*
+
+*   Fix default `format` value in `ActiveRecord::Tasks::DatabaseTasks#schema_file`.
+
+    *James Cox*
+
+*   Don't enroll records in the transaction if they don't have commit callbacks.
+    This was causing a memory leak when creating many records inside a transaction.
+
+    Fixes #15549.
+
+    *Will Bryant*, *Aaron Patterson*
+
+*   Correctly create through records when created on a has many through
+    association when using `where`.
+
+    Fixes #19073.
+
+    *Sean Griffin*
+
+*   Add `SchemaMigration.create_table` support for any unicode charsets with MySQL.
+
+    *Ryuta Kamizono*
+
+*   PostgreSQL no longer disables user triggers if system triggers can't be
+    disabled. Disabling user triggers does not fulfill what the method promises.
+    Rails currently requires superuser privileges for this method.
+
+    If you absolutely rely on this behavior, consider patching
+    `disable_referential_integrity`.
+
+    *Yves Senn*
+
+*   Restore aborted transaction state when `disable_referential_integrity` fails
+    due to missing permissions.
+
+    *Toby Ovod-Everett*, *Yves Senn*
+
+*   In PostgreSQL, print a warning message if `disable_referential_integrity`
+    fails due to missing permissions.
+
+    *Andrey Nering*, *Yves Senn*
+
+*   Allow a `:limit` option for MySQL bigint primary key support.
+
+    Example:
+
+        create_table :foos, id: :primary_key, limit: 8 do |t|
+        end
+
+        # or
+
+        create_table :foos, id: false do |t|
+          t.primary_key :id, limit: 8
+        end
+
+    *Ryuta Kamizono*
+
+*   `belongs_to` will now trigger a validation error by default if the association is not present.
+    You can turn this off on a per-association basis with `optional: true`.
+    (Note this new default only applies to new Rails apps that will be generated with
+    `config.active_record.belongs_to_required_by_default = true` in initializer.)
+
+    *Josef Šimánek*
+
+*   Fixed `ActiveRecord::Relation#becomes!` and `changed_attributes` issues for type
+    columns.
+
+    Fixes #17139.
+
+    *Miklos Fazekas*
+
+*   Format the time string according to the precision of the time column.
+
+    *Ryuta Kamizono*
+
+*   Allow a `:precision` option for time type columns.
+
+    *Ryuta Kamizono*
+
+*   Add `ActiveRecord::Base.suppress` to prevent the receiver from being saved
+    during the given block.
+
+    For example, here's a pattern of creating notifications when new comments
+    are posted. (The notification may in turn trigger an email, a push
+    notification, or just appear in the UI somewhere):
+
+        class Comment < ActiveRecord::Base
+          belongs_to :commentable, polymorphic: true
+          after_create -> { Notification.create! comment: self,
+            recipients: commentable.recipients }
+        end
+
+    That's what you want the bulk of the time. A new comment creates a new
+    Notification. There may be edge cases where you don't want that, like
+    when copying a commentable and its comments, in which case write a
+    concern with something like this:
+
+        module Copyable
+          def copy_to(destination)
+            Notification.suppress do
+              # Copy logic that creates new comments that we do not want triggering
+              # notifications.
+            end
+          end
+        end
+
+    *Michael Ryan*
+
+*   `:time` option added for `#touch`.
+
+    Fixes #18905.
+
+    *Hyonjee Joo*
+
+*   Deprecate passing of `start` value to `find_in_batches` and `find_each`
+    in favour of `begin_at` value.
+
+    *Vipul A M*
+
+*   Add `foreign_key_exists?` method.
+
+    *Tõnis Simo*
+
+*   Use SQL COUNT and LIMIT 1 queries for `none?` and `one?` methods
+    if no block or limit is given, instead of loading the entire
+    collection into memory. This applies to relations (e.g. `User.all`)
+    as well as associations (e.g. `account.users`)
+
+        # Before:
+
+        users.none?
+        # SELECT "users".* FROM "users"
+
+        users.one?
+        # SELECT "users".* FROM "users"
+
+        # After:
+
+        users.none?
+        # SELECT 1 AS one FROM "users" LIMIT 1
+
+        users.one?
+        # SELECT COUNT(*) FROM "users"
+
+    *Eugene Gilburg*
+
+*   Have `enum` perform type casting consistently with the rest of Active
+    Record, such as `where`.
+
+    *Sean Griffin*
+
+*   `scoping` no longer pollutes the current scope of sibling classes when using
+    STI. e.x.
+
+        StiOne.none.scoping do
+          StiTwo.all
+        end
+
+    Fixes #18806.
+
+    *Sean Griffin*
+
+*   `remove_reference` with `foreign_key: true` removes the foreign key before
+    removing the column. This fixes a bug where it was not possible to remove
+    the column on MySQL.
+
+    Fixes #18664.
+
+    *Yves Senn*
+
+*   `find_in_batches` now accepts an `:end_at` parameter that complements the `:start`
+     parameter to specify where to stop batch processing.
+
+    *Vipul A M*
+
+*   Fix a rounding problem for PostgreSQL timestamp columns.
+
+    If a timestamp column has a precision specified, it needs to
+    format according to that.
+
+    *Ryuta Kamizono*
+
+*   Respect the database default charset for `schema_migrations` table.
+
+    The charset of `version` column in `schema_migrations` table depends
+    on the database default charset and collation rather than the encoding
+    of the connection.
+
+    *Ryuta Kamizono*
+
+*   Raise `ArgumentError` when passing `nil` or `false` to `Relation#merge`.
+
+    These are not valid values to merge in a relation, so it should warn users
+    early.
+
+    *Rafael Mendonça França*
+
+*   Use `SCHEMA` instead of `DB_STRUCTURE` for specifying a structure file.
+
+    This makes the db:structure tasks consistent with test:load_structure.
+
+    *Dieter Komendera*
+
+*   Respect custom primary keys for associations when calling `Relation#where`
+
+    Fixes #18813.
+
+    *Sean Griffin*
+
+*   Fix several edge cases which could result in a counter cache updating
+    twice or not updating at all for `has_many` and `has_many :through`.
+
+    Fixes #10865.
+
+    *Sean Griffin*
+
+*   Foreign keys added by migrations were given random, generated names. This
+    meant a different `structure.sql` would be generated every time a developer
+    ran migrations on their machine.
+
+    The generated part of foreign key names is now a hash of the table name and
+    column name, which is consistent every time you run the migration.
+
+    *Chris Sinjakli*
+
+*   Validation errors would be raised for parent records when an association
+    was saved when the parent had `validate: false`. It should not be the
+    responsibility of the model to validate an associated object unless the
+    object was created or modified by the parent.
+
+    This fixes the issue by skipping validations if the parent record is
+    persisted, not changed, and not marked for destruction.
+
+    Fixes #17621.
+
+    *Eileen M. Uchitelle, Aaron Patterson*
+
+*   Fix n+1 query problem when eager loading nil associations (fixes #18312)
+
+    *Sammy Larbi*
+
+*   Change the default error message from `can't be blank` to `must exist` for
+    the presence validator of the `:required` option on `belongs_to`/`has_one`
+    associations.
+
+    *Henrik Nygren*
+
+*   Fixed `ActiveRecord::Relation#group` method when an argument is an SQL
+    reserved keyword:
+
+    Example:
+
+        SplitTest.group(:key).count
+        Property.group(:value).count
+
+    *Bogdan Gusiev*
+
+*   Added the `#or` method on `ActiveRecord::Relation`, allowing use of the OR
+    operator to combine WHERE or HAVING clauses.
+
+    Example:
+
+        Post.where('id = 1').or(Post.where('id = 2'))
+        # => SELECT * FROM posts WHERE (id = 1) OR (id = 2)
+
+    *Sean Griffin*, *Matthew Draper*, *Gael Muller*, *Olivier El Mekki*
+
+*   Don't define autosave association callbacks twice from
+    `accepts_nested_attributes_for`.
+
+    Fixes #18704.
+
+    *Sean Griffin*
+
+*   Integer types will no longer raise a `RangeError` when assigning an
+    attribute, but will instead raise when going to the database.
+
+    Fixes several vague issues which were never reported directly. See the
+    commit message from the commit which added this line for some examples.
+
+    *Sean Griffin*
+
+*   Values which would error while being sent to the database (such as an
+    ASCII-8BIT string with invalid UTF-8 bytes on SQLite3), no longer error on
+    assignment. They will still error when sent to the database, but you are
+    given the ability to re-assign it to a valid value.
+
+    Fixes #18580.
+
+    *Sean Griffin*
+
+*   Don't remove join dependencies in `Relation#exists?`
+
+    Fixes #18632.
+
+    *Sean Griffin*
+
+*   Invalid values assigned to a JSON column are assumed to be `nil`.
+
+    Fixes #18629.
+
+    *Sean Griffin*
+
+*   Add `ActiveRecord::Base#accessed_fields`, which can be used to quickly
+    discover which fields were read from a model when you are looking to only
+    select the data you need from the database.
+
+    *Sean Griffin*
+
+*   Introduce the `:if_exists` option for `drop_table`.
+
+    Example:
+
+        drop_table(:posts, if_exists: true)
+
+    That would execute:
+
+        DROP TABLE IF EXISTS posts
+
+    If the table doesn't exist, `if_exists: false` (the default) raises an
+    exception whereas `if_exists: true` does nothing.
+
+    *Cody Cutrer*, *Stefan Kanev*, *Ryuta Kamizono*
+
+*   Don't run SQL if attribute value is not changed for update_attribute method.
+
+    *Prathamesh Sonpatki*
+
+*   `time` columns can now get affected by `time_zone_aware_attributes`. If you have
     set `config.time_zone` to a value other than `'UTC'`, they will be treated
-    as in that time zone by default in Rails 5.0. If this is not the desired
+    as in that time zone by default in Rails 5.1. If this is not the desired
     behavior, you can set
 
         ActiveRecord::Base.time_zone_aware_types = [:datetime]
@@ -24,10 +1142,19 @@
     A deprecation warning will be emitted if you have a `:time` column, and have
     not explicitly opted out.
 
-    Fixes #3145
+    Fixes #3145.
 
     *Sean Griffin*
 
+*   Tests now run after_commit callbacks. You no longer have to declare
+    `uses_transaction ‘test name’` to test the results of an after_commit.
+
+    after_commit callbacks run after committing a transaction whose parent
+    is not `joinable?`: un-nested transactions, transactions within test cases,
+    and transactions in `console --sandbox`.
+
+    *arthurnn*, *Ravil Bayramgalin*, *Matthew Draper*
+
 *   `nil` as a value for a binary column in a query no longer logs as
     "<NULL binary data>", and instead logs as just "nil".
 
@@ -56,7 +1183,7 @@
 
     *Yves Senn*
 
-*   Remove deprecation when modifying a relation with cached arel.
+*   Remove deprecation when modifying a relation with cached Arel.
     This raises an `ImmutableRelation` error instead.
 
     *Yves Senn*
@@ -134,10 +1261,10 @@
 
     The preferred method to halt a callback chain from now on is to explicitly
     `throw(:abort)`.
-    In the past, returning `false` in an ActiveRecord `before_` callback had the
+    In the past, returning `false` in an Active Record `before_` callback had the
     side effect of halting the callback chain.
     This is not recommended anymore and, depending on the value of the
-    `config.active_support.halt_callback_chains_on_return_false` option, will
+    `ActiveSupport.halt_callback_chains_on_return_false` option, will
     either not work at all or display a deprecation warning.
 
     *claudiob*
@@ -146,13 +1273,13 @@
 
     *Florian Weingarten*
 
-*   Fixed setting of foreign_key for through associations while building of new record.
+*   Fix setting of foreign_key for through associations when building a new record.
 
     Fixes #12698.
 
     *Ivan Antropov*
 
-*   Improve a dump of the primary key support. If it is not a default primary key,
+*   Improve dumping of the primary key. If it is not a default primary key,
     correctly dump the type and options.
 
     Fixes #14169, #16599.
@@ -170,18 +1297,18 @@
 
     *Ryuta Kamizono*
 
-*   Allow precision option for MySQL datetimes.
+*   Allow a precision option for MySQL datetimes.
 
     *Ryuta Kamizono*
 
-*   Fixed automatic inverse_of for models nested in module.
+*   Fixed automatic `inverse_of` for models nested in a module.
 
     *Andrew McCloud*
 
 *   Change `ActiveRecord::Relation#update` behavior so that it can
     be called without passing ids of the records to be updated.
 
-    This change allows to update multiple records returned by
+    This change allows updating multiple records returned by
     `ActiveRecord::Relation` with callbacks and validations.
 
         # Before
@@ -213,6 +1340,13 @@
 
     *Rafael Mendonça França*
 
+*   Fix change detection problem for PostgreSQL bytea type and
+    `ArgumentError: string contains null byte` exception with pg-0.18.
+
+    Fixes #17680.
+
+    *Lars Kanis*
+
 *   When a table has a composite primary key, the `primary_key` method for
     SQLite3 and PostgreSQL adapters was only returning the first field of the key.
     Ensures that it will return nil instead, as Active Record doesn't support
@@ -222,7 +1356,7 @@
 
     *arthurnn*
 
-*   `validates_size_of` / `validates_length_of` do not count records,
+*   `validates_size_of` / `validates_length_of` do not count records
     which are `marked_for_destruction?`.
 
     Fixes #7247.
@@ -237,7 +1371,7 @@
 
 *   `eager_load` preserves readonly flag for associations.
 
-    Closes #15853.
+    Fixes #15853.
 
     *Takashi Kokubun*
 
@@ -264,7 +1398,7 @@
 
     *Ryuta Kamizono*
 
-*   Support for any type primary key.
+*   Support for any type of primary key.
 
     Fixes #14194.
 
@@ -290,10 +1424,10 @@
 
     *Yves Senn*
 
-*   Fixes bug with 'ActiveRecord::Type::Numeric' that causes negative values to
+*   Fix bug with `ActiveRecord::Type::Numeric` that caused negative values to
     be marked as having changed when set to the same negative value.
 
-    Closes #18161.
+    Fixes #18161.
 
     *Daniel Fox*
 
@@ -308,7 +1442,7 @@
     before loading the schema. This is left for the user to do.
     `db:test:prepare` will still purge the database.
 
-    Closes #17945.
+    Fixes #17945.
 
     *Yves Senn*
 
diff --git a/activerecord/README.rdoc b/activerecord/README.rdoc
index f4777919d3..3eac8cc422 100644
--- a/activerecord/README.rdoc
+++ b/activerecord/README.rdoc
@@ -26,13 +26,13 @@ The Product class is automatically mapped to the table named "products",
 which might look like this:
 
    CREATE TABLE products (
-     id int(11) NOT NULL auto_increment,
+     id int NOT NULL auto_increment,
      name varchar(255),
      PRIMARY KEY  (id)
    );
 
-This would also define the following accessors: `Product#name` and
-`Product#name=(new_name)`.
+This would also define the following accessors: <tt>Product#name</tt> and
+<tt>Product#name=(new_name)</tt>.
 
 
 * Associations between objects defined by simple class methods.
@@ -188,7 +188,7 @@ Admit the Database:
 
 The latest version of Active Record can be installed with RubyGems:
 
-  % [sudo] gem install activerecord
+  % gem install activerecord
 
 Source code can be downloaded as part of the Rails project on GitHub:
 
diff --git a/activerecord/Rakefile b/activerecord/Rakefile
index 976b559da9..c93099a921 100644
--- a/activerecord/Rakefile
+++ b/activerecord/Rakefile
@@ -1,5 +1,4 @@
 require 'rake/testtask'
-require 'rubygems/package_task'
 
 require File.expand_path(File.dirname(__FILE__)) + "/test/config"
 require File.expand_path(File.dirname(__FILE__)) + "/test/support/config"
@@ -51,7 +50,7 @@ end
       t.libs << 'test'
       t.test_files = (Dir.glob( "test/cases/**/*_test.rb" ).reject {
         |x| x =~ /\/adapters\//
-      } + Dir.glob("test/cases/adapters/#{adapter_short}/**/*_test.rb")).sort
+      } + Dir.glob("test/cases/adapters/#{adapter_short}/**/*_test.rb"))
 
       t.warning = true
       t.verbose = true
@@ -84,29 +83,20 @@ end
   task "isolated_test_#{adapter}" => ["#{adapter}:env", "test:isolated:#{adapter}"]
 end
 
-rule '.sqlite3' do |t|
-  sh %Q{sqlite3 "#{t.name}" "create table a (a integer); drop table a;"}
-end
-
-task :test_sqlite3 => [
-  'test/fixtures/fixture_database.sqlite3',
-  'test/fixtures/fixture_database_2.sqlite3'
-]
-
 namespace :db do
   namespace :mysql do
     desc 'Build the MySQL test databases'
     task :build do
       config = ARTest.config['connections']['mysql']
-      %x( mysql --user=#{config['arunit']['username']} -e "create DATABASE #{config['arunit']['database']} DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_unicode_ci ")
-      %x( mysql --user=#{config['arunit2']['username']} -e "create DATABASE #{config['arunit2']['database']} DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_unicode_ci ")
+      %x( mysql --user=#{config['arunit']['username']} --password=#{config['arunit']['password']} -e "create DATABASE #{config['arunit']['database']} DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_unicode_ci ")
+      %x( mysql --user=#{config['arunit2']['username']} --password=#{config['arunit2']['password']} -e "create DATABASE #{config['arunit2']['database']} DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_unicode_ci ")
     end
 
     desc 'Drop the MySQL test databases'
     task :drop do
       config = ARTest.config['connections']['mysql']
-      %x( mysqladmin --user=#{config['arunit']['username']} -f drop #{config['arunit']['database']} )
-      %x( mysqladmin --user=#{config['arunit2']['username']} -f drop #{config['arunit2']['database']} )
+      %x( mysqladmin --user=#{config['arunit']['username']} --password=#{config['arunit']['password']} -f drop #{config['arunit']['database']} )
+      %x( mysqladmin --user=#{config['arunit2']['username']} --password=#{config['arunit2']['password']} -f drop #{config['arunit2']['database']} )
     end
 
     desc 'Rebuild the MySQL test databases'
@@ -122,7 +112,7 @@ namespace :db do
 
       # prepare hstore
       if %x( createdb --version ).strip.gsub(/(.*)(\d\.\d\.\d)$/, "\\2") < "9.1.0"
-        puts "Please prepare hstore data type. See http://www.postgresql.org/docs/9.0/static/hstore.html"
+        puts "Please prepare hstore data type. See http://www.postgresql.org/docs/current/static/hstore.html"
       end
     end
 
@@ -151,18 +141,3 @@ task :lines do
   files = FileList["lib/active_record/**/*.rb"]
   CodeTools::LineStatistics.new(files).print_loc
 end
-
-spec = eval(File.read('activerecord.gemspec'))
-
-Gem::PackageTask.new(spec) do |p|
-  p.gem_spec = spec
-end
-
-# Publishing ------------------------------------------------------
-
-desc "Release to rubygems"
-task :release => :package do
-  require 'rake/gemcutter'
-  Rake::Gemcutter::Tasks.new(spec).define
-  Rake::Task['gem:push'].invoke
-end
diff --git a/activerecord/activerecord.gemspec b/activerecord/activerecord.gemspec
index c5cd0c89f7..bd95b57303 100644
--- a/activerecord/activerecord.gemspec
+++ b/activerecord/activerecord.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'Object-relational mapper framework (part of Rails).'
   s.description = 'Databases on Rails. Build a persistent domain model by mapping database tables to Ruby classes. Strong conventions for associations, validations, aggregations, migrations, and testing come baked-in.'
 
-  s.required_ruby_version = '>= 2.2.0'
+  s.required_ruby_version = '>= 2.2.2'
 
   s.license = 'MIT'
 
diff --git a/activerecord/bin/test b/activerecord/bin/test
new file mode 100755
index 0000000000..f8adf2aabc
--- /dev/null
+++ b/activerecord/bin/test
@@ -0,0 +1,19 @@
+#!/usr/bin/env ruby
+COMPONENT_ROOT = File.expand_path("../../", __FILE__)
+require File.expand_path("../tools/test", COMPONENT_ROOT)
+module Minitest
+  def self.plugin_active_record_options(opts, options)
+    opts.separator ""
+    opts.separator "Active Record options:"
+    opts.on("-a", "--adapter [ADAPTER]",
+            "Run tests using a specific adapter (sqlite3, sqlite3_mem, mysql, mysql2, postgresql)") do |adapter|
+      ENV["ARCONN"] = adapter.strip
+    end
+
+    opts
+  end
+end
+
+Minitest.extensions.unshift 'active_record'
+
+exit Minitest.run(ARGV)
diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index d9d47c3d99..264f869c68 100644
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -43,15 +43,19 @@ module ActiveRecord
   autoload :Explain
   autoload :Inheritance
   autoload :Integration
+  autoload :LegacyYamlAdapter
   autoload :Migration
   autoload :Migrator, 'active_record/migration'
   autoload :ModelSchema
   autoload :NestedAttributes
   autoload :NoTouching
+  autoload :TouchLater
   autoload :Persistence
   autoload :QueryCache
   autoload :Querying
+  autoload :CollectionCacheKey
   autoload :ReadonlyAttributes
+  autoload :RecordInvalid, 'active_record/validations'
   autoload :Reflection
   autoload :RuntimeRegistry
   autoload :Sanitization
@@ -62,6 +66,7 @@ module ActiveRecord
   autoload :Serialization
   autoload :StatementCache
   autoload :Store
+  autoload :Suppressor
   autoload :TableMetadata
   autoload :Timestamp
   autoload :Transactions
diff --git a/activerecord/lib/active_record/aggregations.rb b/activerecord/lib/active_record/aggregations.rb
index 1040e6e3bb..be88c7c9e8 100644
--- a/activerecord/lib/active_record/aggregations.rb
+++ b/activerecord/lib/active_record/aggregations.rb
@@ -1,14 +1,31 @@
 module ActiveRecord
-  # = Active Record Aggregations
-  module Aggregations # :nodoc:
+  # See ActiveRecord::Aggregations::ClassMethods for documentation
+  module Aggregations
     extend ActiveSupport::Concern
 
-    def clear_aggregation_cache #:nodoc:
-      @aggregation_cache.clear if persisted?
+    def initialize_dup(*) # :nodoc:
+      @aggregation_cache = {}
+      super
     end
 
-    # Active Record implements aggregation through a macro-like class method called +composed_of+
-    # for representing attributes  as value objects. It expresses relationships like "Account [is]
+    def reload(*) # :nodoc:
+      clear_aggregation_cache
+      super
+    end
+
+    private
+
+      def clear_aggregation_cache # :nodoc:
+        @aggregation_cache.clear if persisted?
+      end
+
+      def init_internals # :nodoc:
+        @aggregation_cache = {}
+        super
+      end
+
+    # Active Record implements aggregation through a macro-like class method called #composed_of
+    # for representing attributes as value objects. It expresses relationships like "Account [is]
     # composed of Money [among other things]" or "Person [is] composed of [an] address". Each call
     # to the macro adds a description of how the value objects are created from the attributes of
     # the entity object (when the entity is initialized either as a new object or from finding an
@@ -87,11 +104,6 @@ module ActiveRecord
     #   customer.address_city   = "Copenhagen"
     #   customer.address        # => Address.new("Hyancintvej", "Copenhagen")
     #
-    #   customer.address_street = "Vesterbrogade"
-    #   customer.address        # => Address.new("Hyancintvej", "Copenhagen")
-    #   customer.clear_aggregation_cache
-    #   customer.address        # => Address.new("Vesterbrogade", "Copenhagen")
-    #
     #   customer.address = Address.new("May Street", "Chicago")
     #   customer.address_street # => "May Street"
     #   customer.address_city   # => "Chicago"
@@ -108,12 +120,12 @@ module ActiveRecord
     #
     # It's also important to treat the value objects as immutable. Don't allow the Money object to have
     # its amount changed after creation. Create a new Money object with the new value instead. The
-    # Money#exchange_to method is an example of this. It returns a new value object instead of changing
+    # <tt>Money#exchange_to</tt> method is an example of this. It returns a new value object instead of changing
     # its own values. Active Record won't persist value objects that have been changed through means
     # other than the writer method.
     #
     # The immutable requirement is enforced by Active Record by freezing any object assigned as a value
-    # object. Attempting to change it afterwards will result in a RuntimeError.
+    # object. Attempting to change it afterwards will result in a +RuntimeError+.
     #
     # Read more about value objects on http://c2.com/cgi/wiki?ValueObject and on the dangers of not
     # keeping value objects immutable on http://c2.com/cgi/wiki?ValueObjectsShouldBeImmutable
@@ -122,17 +134,17 @@ module ActiveRecord
     #
     # By default value objects are initialized by calling the <tt>new</tt> constructor of the value
     # class passing each of the mapped attributes, in the order specified by the <tt>:mapping</tt>
-    # option, as arguments. If the value class doesn't support this convention then +composed_of+ allows
+    # option, as arguments. If the value class doesn't support this convention then #composed_of allows
     # a custom constructor to be specified.
     #
     # When a new value is assigned to the value object, the default assumption is that the new value
     # is an instance of the value class. Specifying a custom converter allows the new value to be automatically
     # converted to an instance of value class if necessary.
     #
-    # For example, the NetworkResource model has +network_address+ and +cidr_range+ attributes that should be
-    # aggregated using the NetAddr::CIDR value class (http://www.ruby-doc.org/gems/docs/n/netaddr-1.5.0/NetAddr/CIDR.html).
+    # For example, the +NetworkResource+ model has +network_address+ and +cidr_range+ attributes that should be
+    # aggregated using the +NetAddr::CIDR+ value class (http://www.rubydoc.info/gems/netaddr/1.5.0/NetAddr/CIDR).
     # The constructor for the value class is called +create+ and it expects a CIDR address string as a parameter.
-    # New values can be assigned to the value object using either another NetAddr::CIDR object, a string
+    # New values can be assigned to the value object using either another +NetAddr::CIDR+ object, a string
     # or an array. The <tt>:constructor</tt> and <tt>:converter</tt> options can be used to meet
     # these requirements:
     #
@@ -161,7 +173,7 @@ module ActiveRecord
     #
     # == Finding records by a value object
     #
-    # Once a +composed_of+ relationship is specified for a model, records can be loaded from the database
+    # Once a #composed_of relationship is specified for a model, records can be loaded from the database
     # by specifying an instance of the value object in the conditions hash. The following example
     # finds all customers with +balance_amount+ equal to 20 and +balance_currency+ equal to "USD":
     #
@@ -174,7 +186,7 @@ module ActiveRecord
       # Options are:
       # * <tt>:class_name</tt> - Specifies the class name of the association. Use it only if that name
       #   can't be inferred from the part id. So <tt>composed_of :address</tt> will by default be linked
-      #   to the Address class, but if the real class name is CompanyAddress, you'll have to specify it
+      #   to the Address class, but if the real class name is +CompanyAddress+, you'll have to specify it
       #   with this option.
       # * <tt>:mapping</tt> - Specifies the mapping of entity attributes to attributes of the value
       #   object. Each mapping is represented as an array where the first item is the name of the
@@ -245,7 +257,8 @@ module ActiveRecord
           define_method("#{name}=") do |part|
             klass = class_name.constantize
             if part.is_a?(Hash)
-              part = klass.new(*part.values)
+              raise ArgumentError unless part.size == part.keys.max
+              part = klass.new(*part.sort.map(&:last))
             end
 
             unless part.is_a?(klass) || converter.nil? || part.nil?
diff --git a/activerecord/lib/active_record/association_relation.rb b/activerecord/lib/active_record/association_relation.rb
index f2b44913db..ee0bb8fafe 100644
--- a/activerecord/lib/active_record/association_relation.rb
+++ b/activerecord/lib/active_record/association_relation.rb
@@ -13,6 +13,19 @@ module ActiveRecord
       other == to_a
     end
 
+    def build(*args, &block)
+      scoping { @association.build(*args, &block) }
+    end
+    alias new build
+
+    def create(*args, &block)
+      scoping { @association.create(*args, &block) }
+    end
+
+    def create!(*args, &block)
+      scoping { @association.create!(*args, &block) }
+    end
+
     private
 
     def exec_queries
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 35bc09bb10..b806a2f832 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -5,95 +5,170 @@ require 'active_record/errors'
 
 module ActiveRecord
   class AssociationNotFoundError < ConfigurationError #:nodoc:
-    def initialize(record, association_name)
-      super("Association named '#{association_name}' was not found on #{record.class.name}; perhaps you misspelled it?")
+    def initialize(record = nil, association_name = nil)
+      if record && association_name
+        super("Association named '#{association_name}' was not found on #{record.class.name}; perhaps you misspelled it?")
+      else
+        super("Association was not found.")
+      end
     end
   end
 
   class InverseOfAssociationNotFoundError < ActiveRecordError #:nodoc:
-    def initialize(reflection, associated_class = nil)
-      super("Could not find the inverse association for #{reflection.name} (#{reflection.options[:inverse_of].inspect} in #{associated_class.nil? ? reflection.class_name : associated_class.name})")
+    def initialize(reflection = nil, associated_class = nil)
+      if reflection
+        super("Could not find the inverse association for #{reflection.name} (#{reflection.options[:inverse_of].inspect} in #{associated_class.nil? ? reflection.class_name : associated_class.name})")
+      else
+        super("Could not find the inverse association.")
+      end
     end
   end
 
   class HasManyThroughAssociationNotFoundError < ActiveRecordError #:nodoc:
-    def initialize(owner_class_name, reflection)
-      super("Could not find the association #{reflection.options[:through].inspect} in model #{owner_class_name}")
+    def initialize(owner_class_name = nil, reflection = nil)
+      if owner_class_name && reflection
+        super("Could not find the association #{reflection.options[:through].inspect} in model #{owner_class_name}")
+      else
+        super("Could not find the association.")
+      end
     end
   end
 
   class HasManyThroughAssociationPolymorphicSourceError < ActiveRecordError #:nodoc:
-    def initialize(owner_class_name, reflection, source_reflection)
-      super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' on the polymorphic object '#{source_reflection.class_name}##{source_reflection.name}' without 'source_type'. Try adding 'source_type: \"#{reflection.name.to_s.classify}\"' to 'has_many :through' definition.")
+    def initialize(owner_class_name = nil, reflection = nil, source_reflection = nil)
+      if owner_class_name && reflection && source_reflection
+        super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' on the polymorphic object '#{source_reflection.class_name}##{source_reflection.name}' without 'source_type'. Try adding 'source_type: \"#{reflection.name.to_s.classify}\"' to 'has_many :through' definition.")
+      else
+        super("Cannot have a has_many :through association.")
+      end
     end
   end
 
   class HasManyThroughAssociationPolymorphicThroughError < ActiveRecordError #:nodoc:
-    def initialize(owner_class_name, reflection)
-      super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' which goes through the polymorphic association '#{owner_class_name}##{reflection.through_reflection.name}'.")
+    def initialize(owner_class_name = nil, reflection = nil)
+      if owner_class_name && reflection
+        super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' which goes through the polymorphic association '#{owner_class_name}##{reflection.through_reflection.name}'.")
+      else
+        super("Cannot have a has_many :through association.")
+      end
     end
   end
 
   class HasManyThroughAssociationPointlessSourceTypeError < ActiveRecordError #:nodoc:
-    def initialize(owner_class_name, reflection, source_reflection)
-      super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' with a :source_type option if the '#{reflection.through_reflection.class_name}##{source_reflection.name}' is not polymorphic. Try removing :source_type on your association.")
+    def initialize(owner_class_name = nil, reflection = nil, source_reflection = nil)
+      if owner_class_name && reflection && source_reflection
+        super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' with a :source_type option if the '#{reflection.through_reflection.class_name}##{source_reflection.name}' is not polymorphic. Try removing :source_type on your association.")
+      else
+        super("Cannot have a has_many :through association.")
+      end
     end
   end
 
   class HasOneThroughCantAssociateThroughCollection < ActiveRecordError #:nodoc:
-    def initialize(owner_class_name, reflection, through_reflection)
-      super("Cannot have a has_one :through association '#{owner_class_name}##{reflection.name}' where the :through association '#{owner_class_name}##{through_reflection.name}' is a collection. Specify a has_one or belongs_to association in the :through option instead.")
+    def initialize(owner_class_name = nil, reflection = nil, through_reflection = nil)
+      if owner_class_name && reflection && through_reflection
+        super("Cannot have a has_one :through association '#{owner_class_name}##{reflection.name}' where the :through association '#{owner_class_name}##{through_reflection.name}' is a collection. Specify a has_one or belongs_to association in the :through option instead.")
+      else
+        super("Cannot have a has_one :through association.")
+      end
     end
   end
 
   class HasOneAssociationPolymorphicThroughError < ActiveRecordError #:nodoc:
-    def initialize(owner_class_name, reflection)
-      super("Cannot have a has_one :through association '#{owner_class_name}##{reflection.name}' which goes through the polymorphic association '#{owner_class_name}##{reflection.through_reflection.name}'.")
+    def initialize(owner_class_name = nil, reflection = nil)
+      if owner_class_name && reflection
+        super("Cannot have a has_one :through association '#{owner_class_name}##{reflection.name}' which goes through the polymorphic association '#{owner_class_name}##{reflection.through_reflection.name}'.")
+      else
+        super("Cannot have a has_one :through association.")
+      end
     end
   end
 
   class HasManyThroughSourceAssociationNotFoundError < ActiveRecordError #:nodoc:
-    def initialize(reflection)
-      through_reflection      = reflection.through_reflection
-      source_reflection_names = reflection.source_reflection_names
-      source_associations     = reflection.through_reflection.klass._reflections.keys
-      super("Could not find the source association(s) #{source_reflection_names.collect(&:inspect).to_sentence(:two_words_connector => ' or ', :last_word_connector => ', or ', :locale => :en)} in model #{through_reflection.klass}. Try 'has_many #{reflection.name.inspect}, :through => #{through_reflection.name.inspect}, :source => <name>'. Is it one of #{source_associations.to_sentence(:two_words_connector => ' or ', :last_word_connector => ', or ', :locale => :en)}?")
+    def initialize(reflection = nil)
+      if reflection
+        through_reflection      = reflection.through_reflection
+        source_reflection_names = reflection.source_reflection_names
+        source_associations     = reflection.through_reflection.klass._reflections.keys
+        super("Could not find the source association(s) #{source_reflection_names.collect(&:inspect).to_sentence(:two_words_connector => ' or ', :last_word_connector => ', or ', :locale => :en)} in model #{through_reflection.klass}. Try 'has_many #{reflection.name.inspect}, :through => #{through_reflection.name.inspect}, :source => <name>'. Is it one of #{source_associations.to_sentence(:two_words_connector => ' or ', :last_word_connector => ', or ', :locale => :en)}?")
+      else
+        super("Could not find the source association(s).")
+      end
     end
   end
 
-  class HasManyThroughCantAssociateThroughHasOneOrManyReflection < ActiveRecordError #:nodoc:
-    def initialize(owner, reflection)
-      super("Cannot modify association '#{owner.class.name}##{reflection.name}' because the source reflection class '#{reflection.source_reflection.class_name}' is associated to '#{reflection.through_reflection.class_name}' via :#{reflection.source_reflection.macro}.")
+  class ThroughCantAssociateThroughHasOneOrManyReflection < ActiveRecordError #:nodoc:
+    def initialize(owner = nil, reflection = nil)
+      if owner && reflection
+        super("Cannot modify association '#{owner.class.name}##{reflection.name}' because the source reflection class '#{reflection.source_reflection.class_name}' is associated to '#{reflection.through_reflection.class_name}' via :#{reflection.source_reflection.macro}.")
+      else
+        super("Cannot modify association.")
+      end
     end
   end
 
+  class HasManyThroughCantAssociateThroughHasOneOrManyReflection < ThroughCantAssociateThroughHasOneOrManyReflection #:nodoc:
+  end
+
+  class HasOneThroughCantAssociateThroughHasOneOrManyReflection < ThroughCantAssociateThroughHasOneOrManyReflection #:nodoc:
+  end
+
   class HasManyThroughCantAssociateNewRecords < ActiveRecordError #:nodoc:
-    def initialize(owner, reflection)
-      super("Cannot associate new records through '#{owner.class.name}##{reflection.name}' on '#{reflection.source_reflection.class_name rescue nil}##{reflection.source_reflection.name rescue nil}'. Both records must have an id in order to create the has_many :through record associating them.")
+    def initialize(owner = nil, reflection = nil)
+      if owner && reflection
+        super("Cannot associate new records through '#{owner.class.name}##{reflection.name}' on '#{reflection.source_reflection.class_name rescue nil}##{reflection.source_reflection.name rescue nil}'. Both records must have an id in order to create the has_many :through record associating them.")
+      else
+        super("Cannot associate new records.")
+      end
     end
   end
 
   class HasManyThroughCantDissociateNewRecords < ActiveRecordError #:nodoc:
-    def initialize(owner, reflection)
-      super("Cannot dissociate new records through '#{owner.class.name}##{reflection.name}' on '#{reflection.source_reflection.class_name rescue nil}##{reflection.source_reflection.name rescue nil}'. Both records must have an id in order to delete the has_many :through record associating them.")
+    def initialize(owner = nil, reflection = nil)
+      if owner && reflection
+        super("Cannot dissociate new records through '#{owner.class.name}##{reflection.name}' on '#{reflection.source_reflection.class_name rescue nil}##{reflection.source_reflection.name rescue nil}'. Both records must have an id in order to delete the has_many :through record associating them.")
+      else
+        super("Cannot dissociate new records.")
+      end
     end
   end
 
-  class HasManyThroughNestedAssociationsAreReadonly < ActiveRecordError #:nodoc:
-    def initialize(owner, reflection)
-      super("Cannot modify association '#{owner.class.name}##{reflection.name}' because it goes through more than one other association.")
+  class ThroughNestedAssociationsAreReadonly < ActiveRecordError #:nodoc:
+    def initialize(owner = nil, reflection = nil)
+      if owner && reflection
+        super("Cannot modify association '#{owner.class.name}##{reflection.name}' because it goes through more than one other association.")
+      else
+        super("Through nested associations are read-only.")
+      end
     end
   end
 
-  class EagerLoadPolymorphicError < ActiveRecordError #:nodoc:
-    def initialize(reflection)
-      super("Cannot eagerly load the polymorphic association #{reflection.name.inspect}")
+  class HasManyThroughNestedAssociationsAreReadonly < ThroughNestedAssociationsAreReadonly #:nodoc:
+  end
+
+  class HasOneThroughNestedAssociationsAreReadonly < ThroughNestedAssociationsAreReadonly #:nodoc:
+  end
+
+  # This error is raised when trying to eager load a polymorphic association using a JOIN.
+  # Eager loading polymorphic associations is only possible with
+  # {ActiveRecord::Relation#preload}[rdoc-ref:QueryMethods#preload].
+  class EagerLoadPolymorphicError < ActiveRecordError
+    def initialize(reflection = nil)
+      if reflection
+        super("Cannot eagerly load the polymorphic association #{reflection.name.inspect}")
+      else
+        super("Eager load polymorphic error.")
+      end
     end
   end
 
   class ReadOnlyAssociation < ActiveRecordError #:nodoc:
-    def initialize(reflection)
-      super("Cannot add to a has_many :through association. Try adding to #{reflection.through_reflection.name.inspect}.")
+    def initialize(reflection = nil)
+      if reflection
+        super("Cannot add to a has_many :through association. Try adding to #{reflection.through_reflection.name.inspect}.")
+      else
+        super("Read-only reflection error.")
+      end
     end
   end
 
@@ -101,8 +176,12 @@ module ActiveRecord
   # (has_many, has_one) when there is at least 1 child associated instance.
   # ex: if @project.tasks.size > 0, DeleteRestrictionError will be raised when trying to destroy @project
   class DeleteRestrictionError < ActiveRecordError #:nodoc:
-    def initialize(name)
-      super("Cannot delete record because of dependent #{name}")
+    def initialize(name = nil)
+      if name
+        super("Cannot delete record because of dependent #{name}")
+      else
+        super("Delete restriction error.")
+      end
     end
   end
 
@@ -113,19 +192,19 @@ module ActiveRecord
 
     # These classes will be loaded when associations are created.
     # So there is no need to eager load them.
-    autoload :Association,           'active_record/associations/association'
-    autoload :SingularAssociation,   'active_record/associations/singular_association'
-    autoload :CollectionAssociation, 'active_record/associations/collection_association'
-    autoload :ForeignAssociation,    'active_record/associations/foreign_association'
-    autoload :CollectionProxy,       'active_record/associations/collection_proxy'
+    autoload :Association
+    autoload :SingularAssociation
+    autoload :CollectionAssociation
+    autoload :ForeignAssociation
+    autoload :CollectionProxy
 
-    autoload :BelongsToAssociation,            'active_record/associations/belongs_to_association'
-    autoload :BelongsToPolymorphicAssociation, 'active_record/associations/belongs_to_polymorphic_association'
-    autoload :HasManyAssociation,              'active_record/associations/has_many_association'
-    autoload :HasManyThroughAssociation,       'active_record/associations/has_many_through_association'
-    autoload :HasOneAssociation,               'active_record/associations/has_one_association'
-    autoload :HasOneThroughAssociation,        'active_record/associations/has_one_through_association'
-    autoload :ThroughAssociation,              'active_record/associations/through_association'
+    autoload :BelongsToAssociation
+    autoload :BelongsToPolymorphicAssociation
+    autoload :HasManyAssociation
+    autoload :HasManyThroughAssociation
+    autoload :HasOneAssociation
+    autoload :HasOneThroughAssociation
+    autoload :ThroughAssociation
 
     module Builder #:nodoc:
       autoload :Association,           'active_record/associations/builder/association'
@@ -139,26 +218,20 @@ module ActiveRecord
     end
 
     eager_autoload do
-      autoload :Preloader,        'active_record/associations/preloader'
-      autoload :JoinDependency,   'active_record/associations/join_dependency'
-      autoload :AssociationScope, 'active_record/associations/association_scope'
-      autoload :AliasTracker,     'active_record/associations/alias_tracker'
+      autoload :Preloader
+      autoload :JoinDependency
+      autoload :AssociationScope
+      autoload :AliasTracker
     end
 
-    # Clears out the association cache.
-    def clear_association_cache #:nodoc:
-      @association_cache.clear if persisted?
-    end
-
-    # :nodoc:
-    attr_reader :association_cache
-
     # Returns the association instance for the given name, instantiating it if it doesn't already exist
     def association(name) #:nodoc:
       association = association_instance_get(name)
 
       if association.nil?
-        raise AssociationNotFoundError.new(self, name) unless reflection = self.class._reflect_on_association(name)
+        unless reflection = self.class._reflect_on_association(name)
+          raise AssociationNotFoundError.new(self, name)
+        end
         association = reflection.association_class.new(self, reflection)
         association_instance_set(name, association)
       end
@@ -166,8 +239,32 @@ module ActiveRecord
       association
     end
 
+    def association_cached?(name) # :nodoc
+      @association_cache.key?(name)
+    end
+
+    def initialize_dup(*) # :nodoc:
+      @association_cache = {}
+      super
+    end
+
+    def reload(*) # :nodoc:
+      clear_association_cache
+      super
+    end
+
     private
-      # Returns the specified association instance if it responds to :loaded?, nil otherwise.
+      # Clears out the association cache.
+      def clear_association_cache # :nodoc:
+        @association_cache.clear if persisted?
+      end
+
+      def init_internals # :nodoc:
+        @association_cache = {}
+        super
+      end
+
+      # Returns the specified association instance if it exists, nil otherwise.
       def association_instance_get(name)
         @association_cache[name]
       end
@@ -204,7 +301,7 @@ module ActiveRecord
     # === A word of warning
     #
     # Don't create associations that have the same name as instance methods of
-    # <tt>ActiveRecord::Base</tt>. Since the association adds a method with that name to
+    # ActiveRecord::Base. Since the association adds a method with that name to
     # its model, it will override the inherited method and break things.
     # For instance, +attributes+ and +connection+ would be bad choices for association names.
     #
@@ -248,7 +345,6 @@ module ActiveRecord
     #   others.find(*args)                |   X   |    X     |    X
     #   others.exists?                    |   X   |    X     |    X
     #   others.distinct                   |   X   |    X     |    X
-    #   others.uniq                       |   X   |    X     |    X
     #   others.reset                      |   X   |    X     |    X
     #
     # === Overriding generated methods
@@ -267,7 +363,7 @@ module ActiveRecord
     #   end
     #
     # If your model class is <tt>Project</tt>, the module is
-    # named <tt>Project::GeneratedFeatureMethods</tt>. The GeneratedFeatureMethods module is
+    # named <tt>Project::GeneratedAssociationMethods</tt>. The +GeneratedAssociationMethods+ module is
     # included in the model class immediately after the (anonymous) generated attributes methods
     # module, meaning an association will override the methods for an attribute with the same name.
     #
@@ -275,12 +371,12 @@ module ActiveRecord
     #
     # Active Record associations can be used to describe one-to-one, one-to-many and many-to-many
     # relationships between models. Each model uses an association to describe its role in
-    # the relation. The +belongs_to+ association is always used in the model that has
+    # the relation. The #belongs_to association is always used in the model that has
     # the foreign key.
     #
     # === One-to-one
     #
-    # Use +has_one+ in the base, and +belongs_to+ in the associated model.
+    # Use #has_one in the base, and #belongs_to in the associated model.
     #
     #   class Employee < ActiveRecord::Base
     #     has_one :office
@@ -291,7 +387,7 @@ module ActiveRecord
     #
     # === One-to-many
     #
-    # Use +has_many+ in the base, and +belongs_to+ in the associated model.
+    # Use #has_many in the base, and #belongs_to in the associated model.
     #
     #   class Manager < ActiveRecord::Base
     #     has_many :employees
@@ -304,7 +400,7 @@ module ActiveRecord
     #
     # There are two ways to build a many-to-many relationship.
     #
-    # The first way uses a +has_many+ association with the <tt>:through</tt> option and a join model, so
+    # The first way uses a #has_many association with the <tt>:through</tt> option and a join model, so
     # there are two stages of associations.
     #
     #   class Assignment < ActiveRecord::Base
@@ -320,7 +416,7 @@ module ActiveRecord
     #     has_many :programmers, through: :assignments
     #   end
     #
-    # For the second way, use +has_and_belongs_to_many+ in both models. This requires a join table
+    # For the second way, use #has_and_belongs_to_many in both models. This requires a join table
     # that has no corresponding model or primary key.
     #
     #   class Programmer < ActiveRecord::Base
@@ -332,13 +428,13 @@ module ActiveRecord
     #
     # Choosing which way to build a many-to-many relationship is not always simple.
     # If you need to work with the relationship model as its own entity,
-    # use <tt>has_many :through</tt>. Use +has_and_belongs_to_many+ when working with legacy schemas or when
+    # use #has_many <tt>:through</tt>. Use #has_and_belongs_to_many when working with legacy schemas or when
     # you never work directly with the relationship itself.
     #
-    # == Is it a +belongs_to+ or +has_one+ association?
+    # == Is it a #belongs_to or #has_one association?
     #
     # Both express a 1-1 relationship. The difference is mostly where to place the foreign
-    # key, which goes on the table for the class declaring the +belongs_to+ relationship.
+    # key, which goes on the table for the class declaring the #belongs_to relationship.
     #
     #   class User < ActiveRecord::Base
     #     # I reference an account.
@@ -353,14 +449,14 @@ module ActiveRecord
     # The tables for these classes could look something like:
     #
     #   CREATE TABLE users (
-    #     id int(11) NOT NULL auto_increment,
-    #     account_id int(11) default NULL,
+    #     id int NOT NULL auto_increment,
+    #     account_id int default NULL,
     #     name varchar default NULL,
     #     PRIMARY KEY  (id)
     #   )
     #
     #   CREATE TABLE accounts (
-    #     id int(11) NOT NULL auto_increment,
+    #     id int NOT NULL auto_increment,
     #     name varchar default NULL,
     #     PRIMARY KEY  (id)
     #   )
@@ -371,35 +467,35 @@ module ActiveRecord
     # there is some special behavior you should be aware of, mostly involving the saving of
     # associated objects.
     #
-    # You can set the <tt>:autosave</tt> option on a <tt>has_one</tt>, <tt>belongs_to</tt>,
-    # <tt>has_many</tt>, or <tt>has_and_belongs_to_many</tt> association. Setting it
+    # You can set the <tt>:autosave</tt> option on a #has_one, #belongs_to,
+    # #has_many, or #has_and_belongs_to_many association. Setting it
     # to +true+ will _always_ save the members, whereas setting it to +false+ will
     # _never_ save the members. More details about <tt>:autosave</tt> option is available at
     # AutosaveAssociation.
     #
     # === One-to-one associations
     #
-    # * Assigning an object to a +has_one+ association automatically saves that object and
+    # * Assigning an object to a #has_one association automatically saves that object and
     #   the object being replaced (if there is one), in order to update their foreign
     #   keys - except if the parent object is unsaved (<tt>new_record? == true</tt>).
     # * If either of these saves fail (due to one of the objects being invalid), an
-    #   <tt>ActiveRecord::RecordNotSaved</tt> exception is raised and the assignment is
+    #   ActiveRecord::RecordNotSaved exception is raised and the assignment is
     #   cancelled.
-    # * If you wish to assign an object to a +has_one+ association without saving it,
-    #   use the <tt>build_association</tt> method (documented below). The object being
+    # * If you wish to assign an object to a #has_one association without saving it,
+    #   use the <tt>#build_association</tt> method (documented below). The object being
     #   replaced will still be saved to update its foreign key.
-    # * Assigning an object to a +belongs_to+ association does not save the object, since
+    # * Assigning an object to a #belongs_to association does not save the object, since
     #   the foreign key field belongs on the parent. It does not save the parent either.
     #
     # === Collections
     #
-    # * Adding an object to a collection (+has_many+ or +has_and_belongs_to_many+) automatically
+    # * Adding an object to a collection (#has_many or #has_and_belongs_to_many) automatically
     #   saves that object, except if the parent object (the owner of the collection) is not yet
     #   stored in the database.
     # * If saving any of the objects being added to a collection (via <tt>push</tt> or similar)
     #   fails, then <tt>push</tt> returns +false+.
     # * If saving fails while replacing the collection (via <tt>association=</tt>), an
-    #   <tt>ActiveRecord::RecordNotSaved</tt> exception is raised and the assignment is
+    #   ActiveRecord::RecordNotSaved exception is raised and the assignment is
     #   cancelled.
     # * You can add an object to a collection without automatically saving it by using the
     #   <tt>collection.build</tt> method (documented below).
@@ -408,14 +504,14 @@ module ActiveRecord
     #
     # == Customizing the query
     #
-    # \Associations are built from <tt>Relation</tt>s, and you can use the <tt>Relation</tt> syntax
+    # \Associations are built from <tt>Relation</tt>s, and you can use the Relation syntax
     # to customize them. For example, to add a condition:
     #
     #   class Blog < ActiveRecord::Base
-    #     has_many :published_posts, -> { where published: true }, class_name: 'Post'
+    #     has_many :published_posts, -> { where(published: true) }, class_name: 'Post'
     #   end
     #
-    # Inside the <tt>-> { ... }</tt> block you can use all of the usual <tt>Relation</tt> methods.
+    # Inside the <tt>-> { ... }</tt> block you can use all of the usual Relation methods.
     #
     # === Accessing the owner object
     #
@@ -424,7 +520,7 @@ module ActiveRecord
     # events that occur on the user's birthday:
     #
     #   class User < ActiveRecord::Base
-    #     has_many :birthday_events, ->(user) { where starts_on: user.birthday }, class_name: 'Event'
+    #     has_many :birthday_events, ->(user) { where(starts_on: user.birthday) }, class_name: 'Event'
     #   end
     #
     # Note: Joining, eager loading and preloading of these associations is not fully possible.
@@ -503,8 +599,8 @@ module ActiveRecord
     #
     # * <tt>record.association(:items).owner</tt> - Returns the object the association is part of.
     # * <tt>record.association(:items).reflection</tt> - Returns the reflection object that describes the association.
-    # * <tt>record.association(:items).target</tt> - Returns the associated object for +belongs_to+ and +has_one+, or
-    #   the collection of associated objects for +has_many+ and +has_and_belongs_to_many+.
+    # * <tt>record.association(:items).target</tt> - Returns the associated object for #belongs_to and #has_one, or
+    #   the collection of associated objects for #has_many and #has_and_belongs_to_many.
     #
     # However, inside the actual extension code, you will not have access to the <tt>record</tt> as
     # above. In this case, you can access <tt>proxy_association</tt>. For example,
@@ -516,7 +612,7 @@ module ActiveRecord
     #
     # Has Many associations can be configured with the <tt>:through</tt> option to use an
     # explicit join model to retrieve the data. This operates similarly to a
-    # +has_and_belongs_to_many+ association. The advantage is that you're able to add validations,
+    # #has_and_belongs_to_many association. The advantage is that you're able to add validations,
     # callbacks, and extra attributes on the join model. Consider the following schema:
     #
     #   class Author < ActiveRecord::Base
@@ -533,7 +629,7 @@ module ActiveRecord
     #   @author.authorships.collect { |a| a.book } # selects all books that the author's authorships belong to
     #   @author.books                              # selects all books by using the Authorship join model
     #
-    # You can also go through a +has_many+ association on the join model:
+    # You can also go through a #has_many association on the join model:
     #
     #   class Firm < ActiveRecord::Base
     #     has_many   :clients
@@ -553,7 +649,7 @@ module ActiveRecord
     #   @firm.clients.flat_map { |c| c.invoices } # select all invoices for all clients of the firm
     #   @firm.invoices                            # selects all invoices by going through the Client join model
     #
-    # Similarly you can go through a +has_one+ association on the join model:
+    # Similarly you can go through a #has_one association on the join model:
     #
     #   class Group < ActiveRecord::Base
     #     has_many   :users
@@ -573,7 +669,7 @@ module ActiveRecord
     #   @group.users.collect { |u| u.avatar }.compact # select all avatars for all users in the group
     #   @group.avatars                                # selects all avatars by going through the User join model.
     #
-    # An important caveat with going through +has_one+ or +has_many+ associations on the
+    # An important caveat with going through #has_one or #has_many associations on the
     # join model is that these associations are *read-only*. For example, the following
     # would not work following the previous example:
     #
@@ -582,26 +678,26 @@ module ActiveRecord
     #
     # == Setting Inverses
     #
-    # If you are using a +belongs_to+ on the join model, it is a good idea to set the
-    # <tt>:inverse_of</tt> option on the +belongs_to+, which will mean that the following example
-    # works correctly (where <tt>tags</tt> is a +has_many+ <tt>:through</tt> association):
+    # If you are using a #belongs_to on the join model, it is a good idea to set the
+    # <tt>:inverse_of</tt> option on the #belongs_to, which will mean that the following example
+    # works correctly (where <tt>tags</tt> is a #has_many <tt>:through</tt> association):
     #
     #   @post = Post.first
     #   @tag = @post.tags.build name: "ruby"
     #   @tag.save
     #
-    # The last line ought to save the through record (a <tt>Taggable</tt>). This will only work if the
+    # The last line ought to save the through record (a <tt>Tagging</tt>). This will only work if the
     # <tt>:inverse_of</tt> is set:
     #
-    #   class Taggable < ActiveRecord::Base
+    #   class Tagging < ActiveRecord::Base
     #     belongs_to :post
     #     belongs_to :tag, inverse_of: :taggings
     #   end
     #
     # If you do not set the <tt>:inverse_of</tt> record, the association will
     # do its best to match itself up with the correct inverse. Automatic
-    # inverse detection only works on <tt>has_many</tt>, <tt>has_one</tt>, and
-    # <tt>belongs_to</tt> associations.
+    # inverse detection only works on #has_many, #has_one, and
+    # #belongs_to associations.
     #
     # Extra options on the associations, as defined in the
     # <tt>AssociationReflection::INVALID_AUTOMATIC_INVERSE_OPTIONS</tt> constant, will
@@ -614,7 +710,7 @@ module ActiveRecord
     # You can turn off the automatic detection of inverse associations by setting
     # the <tt>:inverse_of</tt> option to <tt>false</tt> like so:
     #
-    #   class Taggable < ActiveRecord::Base
+    #   class Tagging < ActiveRecord::Base
     #     belongs_to :tag, inverse_of: false
     #   end
     #
@@ -664,7 +760,7 @@ module ActiveRecord
     # == Polymorphic \Associations
     #
     # Polymorphic associations on models are not restricted on what types of models they
-    # can be associated with. Rather, they specify an interface that a +has_many+ association
+    # can be associated with. Rather, they specify an interface that a #has_many association
     # must adhere to.
     #
     #   class Asset < ActiveRecord::Base
@@ -748,7 +844,7 @@ module ActiveRecord
     #
     #   Post.includes(:author).each do |post|
     #
-    # This references the name of the +belongs_to+ association that also used the <tt>:author</tt>
+    # This references the name of the #belongs_to association that also used the <tt>:author</tt>
     # symbol. After loading the posts, find will collect the +author_id+ from each one and load
     # all the referenced authors with one query. Doing so will cut down the number of queries
     # from 201 to 102.
@@ -759,7 +855,7 @@ module ActiveRecord
     #
     # This will load all comments with a single query. This reduces the total number of queries
     # to 3. In general, the number of queries will be 1 plus the number of associations
-    # named (except if some of the associations are polymorphic +belongs_to+ - see below).
+    # named (except if some of the associations are polymorphic #belongs_to - see below).
     #
     # To include a deep hierarchy of associations, use a hash:
     #
@@ -799,7 +895,7 @@ module ActiveRecord
     # In this case it is usually more natural to include an association which has conditions defined on it:
     #
     #   class Post < ActiveRecord::Base
-    #     has_many :approved_comments, -> { where approved: true }, class_name: 'Comment'
+    #     has_many :approved_comments, -> { where(approved: true) }, class_name: 'Comment'
     #   end
     #
     #   Post.includes(:approved_comments)
@@ -831,7 +927,7 @@ module ActiveRecord
     # For example if all the addressables are either of class Person or Company then a total
     # of 3 queries will be executed. The list of addressable types to load is determined on
     # the back of the addresses loaded. This is not supported if Active Record has to fallback
-    # to the previous implementation of eager loading and will raise <tt>ActiveRecord::EagerLoadPolymorphicError</tt>.
+    # to the previous implementation of eager loading and will raise ActiveRecord::EagerLoadPolymorphicError.
     # The reason is that the parent model's type is a column value so its corresponding table
     # name cannot be put in the +FROM+/+JOIN+ clauses of that query.
     #
@@ -873,7 +969,7 @@ module ActiveRecord
     #                              INNER JOIN categories_posts posts_categories_join INNER JOIN posts posts_categories
     #                              INNER JOIN categories_posts categories_posts_join INNER JOIN categories categories_posts_2
     #
-    # If you wish to specify your own custom joins using <tt>joins</tt> method, those table
+    # If you wish to specify your own custom joins using ActiveRecord::QueryMethods#joins method, those table
     # names will take precedence over the eager associations:
     #
     #   Post.joins(:comments).joins("inner join comments ...")
@@ -938,20 +1034,16 @@ module ActiveRecord
     # The +traps+ association on +Dungeon+ and the +dungeon+ association on +Trap+ are
     # the inverse of each other and the inverse of the +dungeon+ association on +EvilWizard+
     # is the +evil_wizard+ association on +Dungeon+ (and vice-versa). By default,
-    # Active Record doesn't know anything about these inverse relationships and so no object
-    # loading optimization is possible. For example:
+    # Active Record can guess the inverse of the association based on the name
+    # of the class. The result is the following:
     #
     #    d = Dungeon.first
     #    t = d.traps.first
-    #    d.level == t.dungeon.level # => true
-    #    d.level = 10
-    #    d.level == t.dungeon.level # => false
+    #    d.object_id == t.dungeon.object_id # => true
     #
     # The +Dungeon+ instances +d+ and <tt>t.dungeon</tt> in the above example refer to
-    # the same object data from the database, but are actually different in-memory copies
-    # of that data. Specifying the <tt>:inverse_of</tt> option on associations lets you tell
-    # Active Record about inverse relationships and it will optimise object loading. For
-    # example, if we changed our model definitions to:
+    # the same in-memory instance since the association matches the name of the class.
+    # The result would be the same if we added +:inverse_of+ to our model definitions:
     #
     #    class Dungeon < ActiveRecord::Base
     #      has_many :traps, inverse_of: :dungeon
@@ -966,20 +1058,19 @@ module ActiveRecord
     #      belongs_to :dungeon, inverse_of: :evil_wizard
     #    end
     #
-    # Then, from our code snippet above, +d+ and <tt>t.dungeon</tt> are actually the same
-    # in-memory instance and our final <tt>d.level == t.dungeon.level</tt> will return +true+.
-    #
     # There are limitations to <tt>:inverse_of</tt> support:
     #
     # * does not work with <tt>:through</tt> associations.
     # * does not work with <tt>:polymorphic</tt> associations.
-    # * for +belongs_to+ associations +has_many+ inverse associations are ignored.
+    # * for #belongs_to associations #has_many inverse associations are ignored.
+    #
+    # For more information, see the documentation for the +:inverse_of+ option.
     #
     # == Deleting from associations
     #
     # === Dependent associations
     #
-    # +has_many+, +has_one+ and +belongs_to+ associations support the <tt>:dependent</tt> option.
+    # #has_many, #has_one and #belongs_to associations support the <tt>:dependent</tt> option.
     # This allows you to specify that associated records should be deleted when the owner is
     # deleted.
     #
@@ -1000,20 +1091,22 @@ module ActiveRecord
     # callbacks declared either before or after the <tt>:dependent</tt> option
     # can affect what it does.
     #
+    # Note that <tt>:dependent</tt> option is ignored for #has_one <tt>:through</tt> associations.
+    #
     # === Delete or destroy?
     #
-    # +has_many+ and +has_and_belongs_to_many+ associations have the methods <tt>destroy</tt>,
+    # #has_many and #has_and_belongs_to_many associations have the methods <tt>destroy</tt>,
     # <tt>delete</tt>, <tt>destroy_all</tt> and <tt>delete_all</tt>.
     #
-    # For +has_and_belongs_to_many+, <tt>delete</tt> and <tt>destroy</tt> are the same: they
+    # For #has_and_belongs_to_many, <tt>delete</tt> and <tt>destroy</tt> are the same: they
     # cause the records in the join table to be removed.
     #
-    # For +has_many+, <tt>destroy</tt> and <tt>destroy_all</tt> will always call the <tt>destroy</tt> method of the
+    # For #has_many, <tt>destroy</tt> and <tt>destroy_all</tt> will always call the <tt>destroy</tt> method of the
     # record(s) being removed so that callbacks are run. However <tt>delete</tt> and <tt>delete_all</tt> will either
     # do the deletion according to the strategy specified by the <tt>:dependent</tt> option, or
     # if no <tt>:dependent</tt> option is given, then it will follow the default strategy.
-    # The default strategy is <tt>:nullify</tt> (set the foreign keys to <tt>nil</tt>), except for
-    # +has_many+ <tt>:through</tt>, where the default strategy is <tt>delete_all</tt> (delete
+    # The default strategy is to do nothing (leave the foreign keys with the parent ids set), except for
+    # #has_many <tt>:through</tt>, where the default strategy is <tt>delete_all</tt> (delete
     # the join records, without running their callbacks).
     #
     # There is also a <tt>clear</tt> method which is the same as <tt>delete_all</tt>, except that
@@ -1021,13 +1114,13 @@ module ActiveRecord
     #
     # === What gets deleted?
     #
-    # There is a potential pitfall here: +has_and_belongs_to_many+ and +has_many+ <tt>:through</tt>
+    # There is a potential pitfall here: #has_and_belongs_to_many and #has_many <tt>:through</tt>
     # associations have records in join tables, as well as the associated records. So when we
     # call one of these deletion methods, what exactly should be deleted?
     #
     # The answer is that it is assumed that deletion on an association is about removing the
     # <i>link</i> between the owner and the associated object(s), rather than necessarily the
-    # associated objects themselves. So with +has_and_belongs_to_many+ and +has_many+
+    # associated objects themselves. So with #has_and_belongs_to_many and #has_many
     # <tt>:through</tt>, the join records will be deleted, but the associated records won't.
     #
     # This makes sense if you think about it: if you were to call <tt>post.tags.delete(Tag.find_by(name: 'food'))</tt>
@@ -1038,20 +1131,20 @@ module ActiveRecord
     # a person has many projects, and each project has many tasks. If we deleted one of a person's
     # tasks, we would probably not want the project to be deleted. In this scenario, the delete method
     # won't actually work: it can only be used if the association on the join model is a
-    # +belongs_to+. In other situations you are expected to perform operations directly on
+    # #belongs_to. In other situations you are expected to perform operations directly on
     # either the associated records or the <tt>:through</tt> association.
     #
-    # With a regular +has_many+ there is no distinction between the "associated records"
+    # With a regular #has_many there is no distinction between the "associated records"
     # and the "link", so there is only one choice for what gets deleted.
     #
-    # With +has_and_belongs_to_many+ and +has_many+ <tt>:through</tt>, if you want to delete the
+    # With #has_and_belongs_to_many and #has_many <tt>:through</tt>, if you want to delete the
     # associated records themselves, you can always do something along the lines of
     # <tt>person.tasks.each(&:destroy)</tt>.
     #
-    # == Type safety with <tt>ActiveRecord::AssociationTypeMismatch</tt>
+    # == Type safety with ActiveRecord::AssociationTypeMismatch
     #
     # If you attempt to assign an object to an association that doesn't match the inferred
-    # or specified <tt>:class_name</tt>, you'll get an <tt>ActiveRecord::AssociationTypeMismatch</tt>.
+    # or specified <tt>:class_name</tt>, you'll get an ActiveRecord::AssociationTypeMismatch.
     #
     # == Options
     #
@@ -1105,10 +1198,10 @@ module ActiveRecord
       # [collection.size]
       #   Returns the number of associated objects.
       # [collection.find(...)]
-      #   Finds an associated object according to the same rules as <tt>ActiveRecord::Base.find</tt>.
+      #   Finds an associated object according to the same rules as ActiveRecord::FinderMethods#find.
       # [collection.exists?(...)]
       #   Checks whether an associated object with the given conditions exists.
-      #   Uses the same rules as <tt>ActiveRecord::Base.exists?</tt>.
+      #   Uses the same rules as ActiveRecord::FinderMethods#exists?.
       # [collection.build(attributes = {}, ...)]
       #   Returns one or more new objects of the collection type that have been instantiated
       #   with +attributes+ and linked to this object through a foreign key, but have not yet
@@ -1119,7 +1212,7 @@ module ActiveRecord
       #   been saved (if it passed the validation). *Note*: This only works if the base model
       #   already exists in the DB, not if it is a new (unsaved) record!
       # [collection.create!(attributes = {})]
-      #   Does the same as <tt>collection.create</tt>, but raises <tt>ActiveRecord::RecordInvalid</tt>
+      #   Does the same as <tt>collection.create</tt>, but raises ActiveRecord::RecordInvalid
       #   if the record is invalid.
       #
       # === Example
@@ -1171,11 +1264,11 @@ module ActiveRecord
       # [:class_name]
       #   Specify the class name of the association. Use it only if that name can't be inferred
       #   from the association name. So <tt>has_many :products</tt> will by default be linked
-      #   to the Product class, but if the real class name is SpecialProduct, you'll have to
+      #   to the +Product+ class, but if the real class name is +SpecialProduct+, you'll have to
       #   specify it with this option.
       # [:foreign_key]
       #   Specify the foreign key used for the association. By default this is guessed to be the name
-      #   of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_many+
+      #   of this class in lower-case and "_id" suffixed. So a Person class that makes a #has_many
       #   association will use "person_id" as the default <tt>:foreign_key</tt>.
       # [:foreign_type]
       #   Specify the column used to store the associated object's type, if this is a polymorphic
@@ -1199,20 +1292,20 @@ module ActiveRecord
       #   * <tt>:restrict_with_error</tt> causes an error to be added to the owner if there are any associated objects.
       #
       #   If using with the <tt>:through</tt> option, the association on the join model must be
-      #   a +belongs_to+, and the records which get deleted are the join records, rather than
+      #   a #belongs_to, and the records which get deleted are the join records, rather than
       #   the associated records.
       # [:counter_cache]
       #   This option can be used to configure a custom named <tt>:counter_cache.</tt> You only need this option,
-      #   when you customized the name of your <tt>:counter_cache</tt> on the <tt>belongs_to</tt> association.
+      #   when you customized the name of your <tt>:counter_cache</tt> on the #belongs_to association.
       # [:as]
-      #   Specifies a polymorphic interface (See <tt>belongs_to</tt>).
+      #   Specifies a polymorphic interface (See #belongs_to).
       # [:through]
       #   Specifies an association through which to perform the query. This can be any other type
       #   of association, including other <tt>:through</tt> associations. Options for <tt>:class_name</tt>,
       #   <tt>:primary_key</tt> and <tt>:foreign_key</tt> are ignored, as the association uses the
       #   source reflection.
       #
-      #   If the association on the join model is a +belongs_to+, the collection can be modified
+      #   If the association on the join model is a #belongs_to, the collection can be modified
       #   and the records on the <tt>:through</tt> model will be automatically created and removed
       #   as appropriate. Otherwise, the collection is read-only, so you should manipulate the
       #   <tt>:through</tt> association directly.
@@ -1223,13 +1316,13 @@ module ActiveRecord
       #   the appropriate join model records when they are saved. (See the 'Association Join Models'
       #   section above.)
       # [:source]
-      #   Specifies the source association name used by <tt>has_many :through</tt> queries.
+      #   Specifies the source association name used by #has_many <tt>:through</tt> queries.
       #   Only use it if the name cannot be inferred from the association.
       #   <tt>has_many :subscribers, through: :subscriptions</tt> will look for either <tt>:subscribers</tt> or
       #   <tt>:subscriber</tt> on Subscription, unless a <tt>:source</tt> is given.
       # [:source_type]
-      #   Specifies type of the source association used by <tt>has_many :through</tt> queries where the source
-      #   association is a polymorphic +belongs_to+.
+      #   Specifies type of the source association used by #has_many <tt>:through</tt> queries where the source
+      #   association is a polymorphic #belongs_to.
       # [:validate]
       #   If +false+, don't validate the associated objects when saving the parent object. true by default.
       # [:autosave]
@@ -1239,10 +1332,11 @@ module ActiveRecord
       #   +before_save+ callback. Because callbacks are run in the order they are defined, associated objects
       #   may need to be explicitly saved in any user-defined +before_save+ callbacks.
       #
-      #   Note that <tt>accepts_nested_attributes_for</tt> sets <tt>:autosave</tt> to <tt>true</tt>.
+      #   Note that NestedAttributes::ClassMethods#accepts_nested_attributes_for sets
+      #   <tt>:autosave</tt> to <tt>true</tt>.
       # [:inverse_of]
-      #   Specifies the name of the <tt>belongs_to</tt> association on the associated object
-      #   that is the inverse of this <tt>has_many</tt> association. Does not work in combination
+      #   Specifies the name of the #belongs_to association on the associated object
+      #   that is the inverse of this #has_many association. Does not work in combination
       #   with <tt>:through</tt> or <tt>:as</tt> options.
       #   See ActiveRecord::Associations::ClassMethods's overview on Bi-directional associations for more detail.
       # [:extend]
@@ -1251,10 +1345,10 @@ module ActiveRecord
       #   association objects.
       #
       # Option examples:
-      #   has_many :comments, -> { order "posted_on" }
-      #   has_many :comments, -> { includes :author }
+      #   has_many :comments, -> { order("posted_on") }
+      #   has_many :comments, -> { includes(:author) }
       #   has_many :people, -> { where(deleted: false).order("name") }, class_name: "Person"
-      #   has_many :tracks, -> { order "position" }, dependent: :destroy
+      #   has_many :tracks, -> { order("position") }, dependent: :destroy
       #   has_many :comments, dependent: :nullify
       #   has_many :tags, as: :taggable
       #   has_many :reports, -> { readonly }
@@ -1266,8 +1360,8 @@ module ActiveRecord
 
       # Specifies a one-to-one association with another class. This method should only be used
       # if the other class contains the foreign key. If the current class contains the foreign key,
-      # then you should use +belongs_to+ instead. See also ActiveRecord::Associations::ClassMethods's overview
-      # on when to use +has_one+ and when to use +belongs_to+.
+      # then you should use #belongs_to instead. See also ActiveRecord::Associations::ClassMethods's overview
+      # on when to use #has_one and when to use #belongs_to.
       #
       # The following methods for retrieval and query of a single associated object will be added:
       #
@@ -1289,7 +1383,7 @@ module ActiveRecord
       #   with +attributes+, linked to this object through a foreign key, and that
       #   has already been saved (if it passed the validation).
       # [create_association!(attributes = {})]
-      #   Does the same as <tt>create_association</tt>, but raises <tt>ActiveRecord::RecordInvalid</tt>
+      #   Does the same as <tt>create_association</tt>, but raises ActiveRecord::RecordInvalid
       #   if the record is invalid.
       #
       # === Example
@@ -1330,9 +1424,11 @@ module ActiveRecord
       #   * <tt>:nullify</tt> causes the foreign key to be set to +NULL+. Callbacks are not executed.
       #   * <tt>:restrict_with_exception</tt> causes an exception to be raised if there is an associated record
       #   * <tt>:restrict_with_error</tt> causes an error to be added to the owner if there is an associated object
+      #
+      #   Note that <tt>:dependent</tt> option is ignored when using <tt>:through</tt> option.
       # [:foreign_key]
       #   Specify the foreign key used for the association. By default this is guessed to be the name
-      #   of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_one+ association
+      #   of this class in lower-case and "_id" suffixed. So a Person class that makes a #has_one association
       #   will use "person_id" as the default <tt>:foreign_key</tt>.
       # [:foreign_type]
       #   Specify the column used to store the associated object's type, if this is a polymorphic
@@ -1343,20 +1439,20 @@ module ActiveRecord
       # [:primary_key]
       #   Specify the method that returns the primary key used for the association. By default this is +id+.
       # [:as]
-      #   Specifies a polymorphic interface (See <tt>belongs_to</tt>).
+      #   Specifies a polymorphic interface (See #belongs_to).
       # [:through]
       #   Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt>,
       #   <tt>:primary_key</tt>, and <tt>:foreign_key</tt> are ignored, as the association uses the
-      #   source reflection. You can only use a <tt>:through</tt> query through a <tt>has_one</tt>
-      #   or <tt>belongs_to</tt> association on the join model.
+      #   source reflection. You can only use a <tt>:through</tt> query through a #has_one
+      #   or #belongs_to association on the join model.
       # [:source]
-      #   Specifies the source association name used by <tt>has_one :through</tt> queries.
+      #   Specifies the source association name used by #has_one <tt>:through</tt> queries.
       #   Only use it if the name cannot be inferred from the association.
       #   <tt>has_one :favorite, through: :favorites</tt> will look for a
       #   <tt>:favorite</tt> on Favorite, unless a <tt>:source</tt> is given.
       # [:source_type]
-      #   Specifies type of the source association used by <tt>has_one :through</tt> queries where the source
-      #   association is a polymorphic +belongs_to+.
+      #   Specifies type of the source association used by #has_one <tt>:through</tt> queries where the source
+      #   association is a polymorphic #belongs_to.
       # [:validate]
       #   If +false+, don't validate the associated object when saving the parent object. +false+ by default.
       # [:autosave]
@@ -1364,10 +1460,11 @@ module ActiveRecord
       #   when saving the parent object. If false, never save or destroy the associated object.
       #   By default, only save the associated object if it's a new record.
       #
-      #   Note that <tt>accepts_nested_attributes_for</tt> sets <tt>:autosave</tt> to <tt>true</tt>.
+      #   Note that NestedAttributes::ClassMethods#accepts_nested_attributes_for sets
+      #   <tt>:autosave</tt> to <tt>true</tt>.
       # [:inverse_of]
-      #   Specifies the name of the <tt>belongs_to</tt> association on the associated object
-      #   that is the inverse of this <tt>has_one</tt> association. Does not work in combination
+      #   Specifies the name of the #belongs_to association on the associated object
+      #   that is the inverse of this #has_one association. Does not work in combination
       #   with <tt>:through</tt> or <tt>:as</tt> options.
       #   See ActiveRecord::Associations::ClassMethods's overview on Bi-directional associations for more detail.
       # [:required]
@@ -1379,12 +1476,12 @@ module ActiveRecord
       #   has_one :credit_card, dependent: :destroy  # destroys the associated credit card
       #   has_one :credit_card, dependent: :nullify  # updates the associated records foreign
       #                                                 # key value to NULL rather than destroying it
-      #   has_one :last_comment, -> { order 'posted_on' }, class_name: "Comment"
-      #   has_one :project_manager, -> { where role: 'project_manager' }, class_name: "Person"
+      #   has_one :last_comment, -> { order('posted_on') }, class_name: "Comment"
+      #   has_one :project_manager, -> { where(role: 'project_manager') }, class_name: "Person"
       #   has_one :attachment, as: :attachable
-      #   has_one :boss, readonly: :true
+      #   has_one :boss, -> { readonly }
       #   has_one :club, through: :membership
-      #   has_one :primary_address, -> { where primary: true }, through: :addressables, source: :addressable
+      #   has_one :primary_address, -> { where(primary: true) }, through: :addressables, source: :addressable
       #   has_one :credit_card, required: true
       def has_one(name, scope = nil, options = {})
         reflection = Builder::HasOne.build(self, name, scope, options)
@@ -1393,8 +1490,8 @@ module ActiveRecord
 
       # Specifies a one-to-one association with another class. This method should only be used
       # if this class contains the foreign key. If the other class contains the foreign key,
-      # then you should use +has_one+ instead. See also ActiveRecord::Associations::ClassMethods's overview
-      # on when to use +has_one+ and when to use +belongs_to+.
+      # then you should use #has_one instead. See also ActiveRecord::Associations::ClassMethods's overview
+      # on when to use #has_one and when to use #belongs_to.
       #
       # Methods will be added for retrieval and query for a single associated object, for which
       # this object holds an id:
@@ -1414,7 +1511,7 @@ module ActiveRecord
       #   with +attributes+, linked to this object through a foreign key, and that
       #   has already been saved (if it passed the validation).
       # [create_association!(attributes = {})]
-      #   Does the same as <tt>create_association</tt>, but raises <tt>ActiveRecord::RecordInvalid</tt>
+      #   Does the same as <tt>create_association</tt>, but raises ActiveRecord::RecordInvalid
       #   if the record is invalid.
       #
       # === Example
@@ -1434,7 +1531,7 @@ module ActiveRecord
       # when you access the associated object.
       #
       # Scope examples:
-      #   belongs_to :user, -> { where(id: 2) }
+      #   belongs_to :firm, -> { where(id: 2) }
       #   belongs_to :user, -> { joins(:friends) }
       #   belongs_to :level, ->(level) { where("game_level > ?", level.current) }
       #
@@ -1461,12 +1558,12 @@ module ActiveRecord
       # [:dependent]
       #   If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
       #   <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method.
-      #   This option should not be specified when <tt>belongs_to</tt> is used in conjunction with
-      #   a <tt>has_many</tt> relationship on another class because of the potential to leave
+      #   This option should not be specified when #belongs_to is used in conjunction with
+      #   a #has_many relationship on another class because of the potential to leave
       #   orphaned records behind.
       # [:counter_cache]
-      #   Caches the number of belonging objects on the associate class through the use of +increment_counter+
-      #   and +decrement_counter+. The counter cache is incremented when an object of this
+      #   Caches the number of belonging objects on the associate class through the use of CounterCache::ClassMethods#increment_counter
+      #   and CounterCache::ClassMethods#decrement_counter. The counter cache is incremented when an object of this
       #   class is created and decremented when it's destroyed. This requires that a column
       #   named <tt>#{table_name}_count</tt> (such as +comments_count+ for a belonging Comment class)
       #   is used on the associate class (such as a Post class) - that is the migration for
@@ -1488,20 +1585,25 @@ module ActiveRecord
       #   If false, never save or destroy the associated object.
       #   By default, only save the associated object if it's a new record.
       #
-      #   Note that <tt>accepts_nested_attributes_for</tt> sets <tt>:autosave</tt> to <tt>true</tt>.
+      #   Note that NestedAttributes::ClassMethods#accepts_nested_attributes_for
+      #   sets <tt>:autosave</tt> to <tt>true</tt>.
       # [:touch]
       #   If true, the associated object will be touched (the updated_at/on attributes set to current time)
       #   when this record is either saved or destroyed. If you specify a symbol, that attribute
       #   will be updated with the current time in addition to the updated_at/on attribute.
       # [:inverse_of]
-      #   Specifies the name of the <tt>has_one</tt> or <tt>has_many</tt> association on the associated
-      #   object that is the inverse of this <tt>belongs_to</tt> association. Does not work in
+      #   Specifies the name of the #has_one or #has_many association on the associated
+      #   object that is the inverse of this #belongs_to association. Does not work in
       #   combination with the <tt>:polymorphic</tt> options.
       #   See ActiveRecord::Associations::ClassMethods's overview on Bi-directional associations for more detail.
+      # [:optional]
+      #   When set to +true+, the association will not have its presence validated.
       # [:required]
       #   When set to +true+, the association will also have its presence validated.
       #   This will validate the association itself, not the id. You can use
       #   +:inverse_of+ to avoid an extra query during validation.
+      #   NOTE: <tt>required</tt> is set to <tt>true</tt> by default and is deprecated. If
+      #   you don't want to have association presence validated, use <tt>optional: true</tt>.
       #
       # Option examples:
       #   belongs_to :firm, foreign_key: "client_of"
@@ -1510,11 +1612,11 @@ module ActiveRecord
       #   belongs_to :valid_coupon, ->(o) { where "discounts > ?", o.payments_count },
       #                             class_name: "Coupon", foreign_key: "coupon_id"
       #   belongs_to :attachable, polymorphic: true
-      #   belongs_to :project, readonly: true
+      #   belongs_to :project, -> { readonly }
       #   belongs_to :post, counter_cache: true
-      #   belongs_to :company, touch: true
+      #   belongs_to :comment, touch: true
       #   belongs_to :company, touch: :employees_last_updated_at
-      #   belongs_to :company, required: true
+      #   belongs_to :user, optional: true
       def belongs_to(name, scope = nil, options = {})
         reflection = Builder::BelongsTo.build(self, name, scope, options)
         Reflection.add_reflection self, name, reflection
@@ -1539,10 +1641,7 @@ module ActiveRecord
       #
       #   class CreateDevelopersProjectsJoinTable < ActiveRecord::Migration
       #     def change
-      #       create_table :developers_projects, id: false do |t|
-      #         t.integer :developer_id
-      #         t.integer :project_id
-      #       end
+      #       create_join_table :developers, :projects
       #     end
       #   end
       #
@@ -1584,10 +1683,10 @@ module ActiveRecord
       # [collection.find(id)]
       #   Finds an associated object responding to the +id+ and that
       #   meets the condition that it has to be associated with this object.
-      #   Uses the same rules as <tt>ActiveRecord::Base.find</tt>.
+      #   Uses the same rules as ActiveRecord::FinderMethods#find.
       # [collection.exists?(...)]
       #   Checks whether an associated object with the given conditions exists.
-      #   Uses the same rules as <tt>ActiveRecord::Base.exists?</tt>.
+      #   Uses the same rules as ActiveRecord::FinderMethods#exists?.
       # [collection.build(attributes = {})]
       #   Returns a new object of the collection type that has been instantiated
       #   with +attributes+ and linked to this object through the join table, but has not yet been saved.
@@ -1622,7 +1721,7 @@ module ActiveRecord
       # query when you access the associated collection.
       #
       # Scope examples:
-      #   has_and_belongs_to_many :projects, -> { includes :milestones, :manager }
+      #   has_and_belongs_to_many :projects, -> { includes(:milestones, :manager) }
       #   has_and_belongs_to_many :categories, ->(category) {
       #     where("default_category = ?", category.name)
       #   }
@@ -1651,19 +1750,17 @@ module ActiveRecord
       # [:join_table]
       #   Specify the name of the join table if the default based on lexical order isn't what you want.
       #   <b>WARNING:</b> If you're overwriting the table name of either class, the +table_name+ method
-      #   MUST be declared underneath any +has_and_belongs_to_many+ declaration in order to work.
+      #   MUST be declared underneath any #has_and_belongs_to_many declaration in order to work.
       # [:foreign_key]
       #   Specify the foreign key used for the association. By default this is guessed to be the name
       #   of this class in lower-case and "_id" suffixed. So a Person class that makes
-      #   a +has_and_belongs_to_many+ association to Project will use "person_id" as the
+      #   a #has_and_belongs_to_many association to Project will use "person_id" as the
       #   default <tt>:foreign_key</tt>.
       # [:association_foreign_key]
       #   Specify the foreign key used for the association on the receiving side of the association.
       #   By default this is guessed to be the name of the associated class in lower-case and "_id" suffixed.
-      #   So if a Person class makes a +has_and_belongs_to_many+ association to Project,
+      #   So if a Person class makes a #has_and_belongs_to_many association to Project,
       #   the association will use "project_id" as the default <tt>:association_foreign_key</tt>.
-      # [:readonly]
-      #   If true, all the associated objects are readonly through the association.
       # [:validate]
       #   If +false+, don't validate the associated objects when saving the parent object. +true+ by default.
       # [:autosave]
@@ -1672,11 +1769,12 @@ module ActiveRecord
       #   If false, never save or destroy the associated objects.
       #   By default, only save associated objects that are new records.
       #
-      #   Note that <tt>accepts_nested_attributes_for</tt> sets <tt>:autosave</tt> to <tt>true</tt>.
+      #   Note that NestedAttributes::ClassMethods#accepts_nested_attributes_for sets
+      #   <tt>:autosave</tt> to <tt>true</tt>.
       #
       # Option examples:
       #   has_and_belongs_to_many :projects
-      #   has_and_belongs_to_many :projects, -> { includes :milestones, :manager }
+      #   has_and_belongs_to_many :projects, -> { includes(:milestones, :manager) }
       #   has_and_belongs_to_many :nations, class_name: "Country"
       #   has_and_belongs_to_many :categories, join_table: "prods_cats"
       #   has_and_belongs_to_many :categories, -> { readonly }
@@ -1692,16 +1790,14 @@ module ActiveRecord
 
         join_model = builder.through_model
 
-        # FIXME: we should move this to the internal constants. Also people
-        # should never directly access this constant so I'm not happy about
-        # setting it.
         const_set join_model.name, join_model
+        private_constant join_model.name
 
         middle_reflection = builder.middle_reflection join_model
 
         Builder::HasMany.define_callbacks self, middle_reflection
         Reflection.add_reflection self, middle_reflection.name, middle_reflection
-        middle_reflection.parent_reflection = [name.to_s, habtm_reflection]
+        middle_reflection.parent_reflection = habtm_reflection
 
         include Module.new {
           class_eval <<-RUBY, __FILE__, __LINE__ + 1
@@ -1717,12 +1813,12 @@ module ActiveRecord
         hm_options[:through] = middle_reflection.name
         hm_options[:source] = join_model.right_reflection.name
 
-        [:before_add, :after_add, :before_remove, :after_remove, :autosave, :validate, :join_table, :class_name].each do |k|
+        [:before_add, :after_add, :before_remove, :after_remove, :autosave, :validate, :join_table, :class_name, :extend].each do |k|
           hm_options[k] = options[k] if options.key? k
         end
 
         has_many name, scope, hm_options, &extension
-        self._reflections[name.to_s].parent_reflection = [name.to_s, habtm_reflection]
+        self._reflections[name.to_s].parent_reflection = habtm_reflection
       end
     end
   end
diff --git a/activerecord/lib/active_record/associations/alias_tracker.rb b/activerecord/lib/active_record/associations/alias_tracker.rb
index 2b7e4f28c5..021bc32237 100644
--- a/activerecord/lib/active_record/associations/alias_tracker.rb
+++ b/activerecord/lib/active_record/associations/alias_tracker.rb
@@ -2,8 +2,7 @@ require 'active_support/core_ext/string/conversions'
 
 module ActiveRecord
   module Associations
-    # Keeps track of table aliases for ActiveRecord::Associations::ClassMethods::JoinDependency and
-    # ActiveRecord::Associations::ThroughAssociationScope
+    # Keeps track of table aliases for ActiveRecord::Associations::JoinDependency
     class AliasTracker # :nodoc:
       attr_reader :aliases
 
diff --git a/activerecord/lib/active_record/associations/association.rb b/activerecord/lib/active_record/associations/association.rb
index 0d8e4ba870..c7b396f3d4 100644
--- a/activerecord/lib/active_record/associations/association.rb
+++ b/activerecord/lib/active_record/associations/association.rb
@@ -8,12 +8,12 @@ module ActiveRecord
     #
     #   Association
     #     SingularAssociation
-    #       HasOneAssociation
+    #       HasOneAssociation + ForeignAssociation
     #         HasOneThroughAssociation + ThroughAssociation
     #       BelongsToAssociation
     #         BelongsToPolymorphicAssociation
     #     CollectionAssociation
-    #       HasManyAssociation
+    #       HasManyAssociation + ForeignAssociation
     #         HasManyThroughAssociation + ThroughAssociation
     class Association #:nodoc:
       attr_reader :owner, :target, :reflection
@@ -211,9 +211,12 @@ module ActiveRecord
         # the kind of the class of the associated objects. Meant to be used as
         # a sanity check when you are about to assign an associated record.
         def raise_on_type_mismatch!(record)
-          unless record.is_a?(reflection.klass) || record.is_a?(reflection.class_name.constantize)
-            message = "#{reflection.class_name}(##{reflection.klass.object_id}) expected, got #{record.class}(##{record.class.object_id})"
-            raise ActiveRecord::AssociationTypeMismatch, message
+          unless record.is_a?(reflection.klass)
+            fresh_class = reflection.class_name.safe_constantize
+            unless fresh_class && record.is_a?(fresh_class)
+              message = "#{reflection.class_name}(##{reflection.klass.object_id}) expected, got #{record.class}(##{record.class.object_id})"
+              raise ActiveRecord::AssociationTypeMismatch, message
+            end
           end
         end
 
@@ -248,6 +251,14 @@ module ActiveRecord
             initialize_attributes(record)
           end
         end
+
+        # Returns true if statement cache should be skipped on the association reader.
+        def skip_statement_cache?
+          reflection.scope_chain.any?(&:any?) ||
+            scope.eager_loading? ||
+            klass.scope_attributes? ||
+            reflection.source_reflection.active_record.default_scopes.any?
+        end
     end
   end
 end
diff --git a/activerecord/lib/active_record/associations/association_scope.rb b/activerecord/lib/active_record/associations/association_scope.rb
index d06b7b3508..48437a1c9e 100644
--- a/activerecord/lib/active_record/associations/association_scope.rb
+++ b/activerecord/lib/active_record/associations/association_scope.rb
@@ -2,42 +2,30 @@ module ActiveRecord
   module Associations
     class AssociationScope #:nodoc:
       def self.scope(association, connection)
-        INSTANCE.scope association, connection
-      end
-
-      class BindSubstitution
-        def initialize(block)
-          @block = block
-        end
-
-        def bind_value(scope, column, value, connection)
-          substitute = connection.substitute_at(column)
-          scope.bind_values += [[column, @block.call(value)]]
-          substitute
-        end
+        INSTANCE.scope(association, connection)
       end
 
       def self.create(&block)
-        block = block ? block : lambda { |val| val }
-        new BindSubstitution.new(block)
+        block ||= lambda { |val| val }
+        new(block)
       end
 
-      def initialize(bind_substitution)
-        @bind_substitution = bind_substitution
+      def initialize(value_transformation)
+        @value_transformation = value_transformation
       end
 
       INSTANCE = create
 
       def scope(association, connection)
-        klass         = association.klass
-        reflection    = association.reflection
-        scope         = klass.unscoped
-        owner         = association.owner
+        klass = association.klass
+        reflection = association.reflection
+        scope = klass.unscoped
+        owner = association.owner
         alias_tracker = AliasTracker.create connection, association.klass.table_name, klass.type_caster
         chain_head, chain_tail = get_chain(reflection, association, alias_tracker)
 
         scope.extending! Array(reflection.options[:extend])
-        add_constraints(scope, owner, klass, reflection, connection, chain_head, chain_tail)
+        add_constraints(scope, owner, klass, reflection, chain_head, chain_tail)
       end
 
       def join_type
@@ -61,43 +49,36 @@ module ActiveRecord
         binds
       end
 
+      protected
+
+      attr_reader :value_transformation
+
       private
       def join(table, constraint)
         table.create_join(table, table.create_on(constraint), join_type)
       end
 
-      def column_for(table_name, column_name, connection)
-        columns = connection.schema_cache.columns_hash(table_name)
-        columns[column_name]
-      end
-
-      def bind_value(scope, column, value, connection)
-        @bind_substitution.bind_value scope, column, value, connection
-      end
-
-      def bind(scope, table_name, column_name, value, connection)
-        column   = column_for table_name, column_name, connection
-        bind_value scope, column, value, connection
-      end
-
-      def last_chain_scope(scope, table, reflection, owner, connection, association_klass)
+      def last_chain_scope(scope, table, reflection, owner, association_klass)
         join_keys = reflection.join_keys(association_klass)
         key = join_keys.key
         foreign_key = join_keys.foreign_key
 
-        bind_val = bind scope, table.table_name, key.to_s, owner[foreign_key], connection
-        scope    = scope.where(table[key].eq(bind_val))
+        value = transform_value(owner[foreign_key])
+        scope = scope.where(table.name => { key => value })
 
         if reflection.type
-          value    = owner.class.base_class.name
-          bind_val = bind scope, table.table_name, reflection.type, value, connection
-          scope    = scope.where(table[reflection.type].eq(bind_val))
-        else
-          scope
+          polymorphic_type = transform_value(owner.class.base_class.name)
+          scope = scope.where(table.name => { reflection.type => polymorphic_type })
         end
+
+        scope
+      end
+
+      def transform_value(value)
+        value_transformation.call(value)
       end
 
-      def next_chain_scope(scope, table, reflection, connection, association_klass, foreign_table, next_reflection)
+      def next_chain_scope(scope, table, reflection, association_klass, foreign_table, next_reflection)
         join_keys = reflection.join_keys(association_klass)
         key = join_keys.key
         foreign_key = join_keys.foreign_key
@@ -105,9 +86,8 @@ module ActiveRecord
         constraint = table[key].eq(foreign_table[foreign_key])
 
         if reflection.type
-          value    = next_reflection.klass.base_class.name
-          bind_val = bind scope, table.table_name, reflection.type, value, connection
-          scope    = scope.where(table[reflection.type].eq(bind_val))
+          value = transform_value(next_reflection.klass.base_class.name)
+          scope = scope.where(table.name => { reflection.type => value })
         end
 
         scope = scope.joins(join(foreign_table, constraint))
@@ -138,10 +118,10 @@ module ActiveRecord
         [runtime_reflection, previous_reflection]
       end
 
-      def add_constraints(scope, owner, association_klass, refl, connection, chain_head, chain_tail)
+      def add_constraints(scope, owner, association_klass, refl, chain_head, chain_tail)
         owner_reflection = chain_tail
         table = owner_reflection.alias_name
-        scope = last_chain_scope(scope, table, owner_reflection, owner, connection, association_klass)
+        scope = last_chain_scope(scope, table, owner_reflection, owner, association_klass)
 
         reflection = chain_head
         loop do
@@ -151,7 +131,7 @@ module ActiveRecord
           unless reflection == chain_tail
             next_reflection = reflection.next
             foreign_table = next_reflection.alias_name
-            scope = next_chain_scope(scope, table, reflection, connection, association_klass, foreign_table, next_reflection)
+            scope = next_chain_scope(scope, table, reflection, association_klass, foreign_table, next_reflection)
           end
 
           # Exclude the scope of the association itself, because that
@@ -160,15 +140,15 @@ module ActiveRecord
             item  = eval_scope(reflection.klass, scope_chain_item, owner)
 
             if scope_chain_item == refl.scope
-              scope.merge! item.except(:where, :includes, :bind)
+              scope.merge! item.except(:where, :includes)
             end
 
             reflection.all_includes do
               scope.includes! item.includes_values
             end
 
-            scope.where_values += item.where_values
-            scope.bind_values  += item.bind_values
+            scope.unscope!(*item.unscope_values)
+            scope.where_clause += item.where_clause
             scope.order_values |= item.order_values
           end
 
diff --git a/activerecord/lib/active_record/associations/belongs_to_association.rb b/activerecord/lib/active_record/associations/belongs_to_association.rb
index c63b42e2a0..41698c5360 100644
--- a/activerecord/lib/active_record/associations/belongs_to_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_association.rb
@@ -10,7 +10,7 @@ module ActiveRecord
       def replace(record)
         if record
           raise_on_type_mismatch!(record)
-          update_counters(record)
+          update_counters_on_replace(record)
           replace_keys(record)
           set_inverse_instance(record)
           @updated = true
@@ -32,42 +32,37 @@ module ActiveRecord
       end
 
       def decrement_counters # :nodoc:
-        with_cache_name { |name| decrement_counter name }
+        update_counters(-1)
       end
 
       def increment_counters # :nodoc:
-        with_cache_name { |name| increment_counter name }
+        update_counters(1)
       end
 
       private
 
-        def find_target?
-          !loaded? && foreign_key_present? && klass
-        end
-
-        def with_cache_name
-          counter_cache_name = reflection.counter_cache_column
-          return unless counter_cache_name && owner.persisted?
-          yield counter_cache_name
+        def update_counters(by)
+          if require_counter_update? && foreign_key_present?
+            if target && !stale_target?
+              target.increment!(reflection.counter_cache_column, by)
+            else
+              klass.update_counters(target_id, reflection.counter_cache_column => by)
+            end
+          end
         end
 
-        def update_counters(record)
-          with_cache_name do |name|
-            return unless different_target? record
-            record.class.increment_counter(name, record.id)
-            decrement_counter name
-          end
+        def find_target?
+          !loaded? && foreign_key_present? && klass
         end
 
-        def decrement_counter(counter_cache_name)
-          if foreign_key_present?
-            klass.decrement_counter(counter_cache_name, target_id)
-          end
+        def require_counter_update?
+          reflection.counter_cache_column && owner.persisted?
         end
 
-        def increment_counter(counter_cache_name)
-          if foreign_key_present?
-            klass.increment_counter(counter_cache_name, target_id)
+        def update_counters_on_replace(record)
+          if require_counter_update? && different_target?(record)
+            record.increment!(reflection.counter_cache_column)
+            decrement_counters
           end
         end
 
@@ -104,7 +99,7 @@ module ActiveRecord
         end
 
         def stale_state
-          result = owner._read_attribute(reflection.foreign_key)
+          result = owner._read_attribute(reflection.foreign_key) { |n| owner.send(:missing_attribute, n, caller) }
           result && result.to_s
         end
     end
diff --git a/activerecord/lib/active_record/associations/builder/association.rb b/activerecord/lib/active_record/associations/builder/association.rb
index 88406740d8..d0534056d9 100644
--- a/activerecord/lib/active_record/associations/builder/association.rb
+++ b/activerecord/lib/active_record/associations/builder/association.rb
@@ -9,14 +9,14 @@
 #    - CollectionAssociation
 #      - HasManyAssociation
 
-module ActiveRecord::Associations::Builder
+module ActiveRecord::Associations::Builder # :nodoc:
   class Association #:nodoc:
     class << self
       attr_accessor :extensions
     end
     self.extensions = []
 
-    VALID_OPTIONS = [:class_name, :class, :foreign_key, :validate] # :nodoc:
+    VALID_OPTIONS = [:class_name, :anonymous_class, :foreign_key, :validate] # :nodoc:
 
     def self.build(model, name, scope, options, &block)
       if model.dangerous_attribute_method?(name)
diff --git a/activerecord/lib/active_record/associations/builder/belongs_to.rb b/activerecord/lib/active_record/associations/builder/belongs_to.rb
index d0ad57f9c6..dae468ba54 100644
--- a/activerecord/lib/active_record/associations/builder/belongs_to.rb
+++ b/activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -1,11 +1,11 @@
-module ActiveRecord::Associations::Builder
+module ActiveRecord::Associations::Builder # :nodoc:
   class BelongsTo < SingularAssociation #:nodoc:
     def self.macro
       :belongs_to
     end
 
     def self.valid_options(options)
-      super + [:foreign_type, :polymorphic, :touch, :counter_cache]
+      super + [:foreign_type, :polymorphic, :touch, :counter_cache, :optional]
     end
 
     def self.valid_dependent_options
@@ -33,16 +33,24 @@ module ActiveRecord::Associations::Builder
 
           if (@_after_create_counter_called ||= false)
             @_after_create_counter_called = false
-          elsif attribute_changed?(foreign_key) && !new_record? && reflection.constructable?
-            model           = reflection.klass
+          elsif attribute_changed?(foreign_key) && !new_record?
+            if reflection.polymorphic?
+              model     = attribute(reflection.foreign_type).try(:constantize)
+              model_was = attribute_was(reflection.foreign_type).try(:constantize)
+            else
+              model     = reflection.klass
+              model_was = reflection.klass
+            end
+
             foreign_key_was = attribute_was foreign_key
             foreign_key     = attribute foreign_key
 
             if foreign_key && model.respond_to?(:increment_counter)
               model.increment_counter(cache_column, foreign_key)
             end
-            if foreign_key_was && model.respond_to?(:decrement_counter)
-              model.decrement_counter(cache_column, foreign_key_was)
+
+            if foreign_key_was && model_was.respond_to?(:decrement_counter)
+              model_was.decrement_counter(cache_column, foreign_key_was)
             end
           end
         end
@@ -60,7 +68,7 @@ module ActiveRecord::Associations::Builder
       klass.attr_readonly cache_column if klass && klass.respond_to?(:attr_readonly)
     end
 
-    def self.touch_record(o, foreign_key, name, touch) # :nodoc:
+    def self.touch_record(o, foreign_key, name, touch, touch_method) # :nodoc:
       old_foreign_id = o.changed_attributes[foreign_key]
 
       if old_foreign_id
@@ -75,9 +83,9 @@ module ActiveRecord::Associations::Builder
 
         if old_record
           if touch != true
-            old_record.touch touch
+            old_record.send(touch_method, touch)
           else
-            old_record.touch
+            old_record.send(touch_method)
           end
         end
       end
@@ -85,9 +93,9 @@ module ActiveRecord::Associations::Builder
       record = o.send name
       if record && record.persisted?
         if touch != true
-          record.touch touch
+          record.send(touch_method, touch)
         else
-          record.touch
+          record.send(touch_method)
         end
       end
     end
@@ -98,7 +106,8 @@ module ActiveRecord::Associations::Builder
       touch       = reflection.options[:touch]
 
       callback = lambda { |record|
-        BelongsTo.touch_record(record, foreign_key, n, touch)
+        touch_method = touching_delayed_records? ? :touch : :touch_later
+        BelongsTo.touch_record(record, foreign_key, n, touch, touch_method)
       }
 
       model.after_save    callback, if: :changed?
@@ -110,5 +119,23 @@ module ActiveRecord::Associations::Builder
       name = reflection.name
       model.after_destroy lambda { |o| o.association(name).handle_dependency }
     end
+
+    def self.define_validations(model, reflection)
+      if reflection.options.key?(:required)
+        reflection.options[:optional] = !reflection.options.delete(:required)
+      end
+
+      if reflection.options[:optional].nil?
+        required = model.belongs_to_required_by_default
+      else
+        required = !reflection.options[:optional]
+      end
+
+      super
+
+      if required
+        model.validates_presence_of reflection.name, message: :required
+      end
+    end
   end
 end
diff --git a/activerecord/lib/active_record/associations/builder/collection_association.rb b/activerecord/lib/active_record/associations/builder/collection_association.rb
index 2ff67f904d..56a8dc4e18 100644
--- a/activerecord/lib/active_record/associations/builder/collection_association.rb
+++ b/activerecord/lib/active_record/associations/builder/collection_association.rb
@@ -2,7 +2,7 @@
 
 require 'active_record/associations'
 
-module ActiveRecord::Associations::Builder
+module ActiveRecord::Associations::Builder # :nodoc:
   class CollectionAssociation < Association #:nodoc:
 
     CALLBACKS = [:before_add, :after_add, :before_remove, :after_remove]
diff --git a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
index 93dc4ae118..a5c9f1666e 100644
--- a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
+++ b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
@@ -1,9 +1,9 @@
-module ActiveRecord::Associations::Builder
+module ActiveRecord::Associations::Builder # :nodoc:
   class HasAndBelongsToMany # :nodoc:
-    class JoinTableResolver
+    class JoinTableResolver # :nodoc:
       KnownTable = Struct.new :join_table
 
-      class KnownClass
+      class KnownClass # :nodoc:
         def initialize(lhs_class, rhs_class_name)
           @lhs_class      = lhs_class
           @rhs_class_name = rhs_class_name
@@ -46,7 +46,7 @@ module ActiveRecord::Associations::Builder
 
       join_model = Class.new(ActiveRecord::Base) {
         class << self;
-          attr_accessor :class_resolver
+          attr_accessor :left_model
           attr_accessor :name
           attr_accessor :table_name_resolver
           attr_accessor :left_reflection
@@ -58,7 +58,7 @@ module ActiveRecord::Associations::Builder
         end
 
         def self.compute_type(class_name)
-          class_resolver.compute_type class_name
+          left_model.compute_type class_name
         end
 
         def self.add_left_association(name, options)
@@ -72,20 +72,24 @@ module ActiveRecord::Associations::Builder
           self.right_reflection = _reflect_on_association(rhs_name)
         end
 
+        def self.retrieve_connection
+          left_model.retrieve_connection
+        end
+
       }
 
       join_model.name                = "HABTM_#{association_name.to_s.camelize}"
       join_model.table_name_resolver = habtm
-      join_model.class_resolver      = lhs_model
+      join_model.left_model          = lhs_model
 
-      join_model.add_left_association :left_side, class: lhs_model
+      join_model.add_left_association :left_side, anonymous_class: lhs_model
       join_model.add_right_association association_name, belongs_to_options(options)
       join_model
     end
 
     def middle_reflection(join_model)
       middle_name = [lhs_model.name.downcase.pluralize,
-                     association_name].join('_').gsub(/::/, '_').to_sym
+                     association_name].join('_'.freeze).gsub('::'.freeze, '_'.freeze).to_sym
       middle_options = middle_options join_model
 
       HasMany.create_reflection(lhs_model,
diff --git a/activerecord/lib/active_record/associations/builder/has_many.rb b/activerecord/lib/active_record/associations/builder/has_many.rb
index 1c1b47bd56..7864d4c536 100644
--- a/activerecord/lib/active_record/associations/builder/has_many.rb
+++ b/activerecord/lib/active_record/associations/builder/has_many.rb
@@ -1,11 +1,11 @@
-module ActiveRecord::Associations::Builder
+module ActiveRecord::Associations::Builder # :nodoc:
   class HasMany < CollectionAssociation #:nodoc:
     def self.macro
       :has_many
     end
 
     def self.valid_options(options)
-      super + [:primary_key, :dependent, :as, :through, :source, :source_type, :inverse_of, :counter_cache, :join_table, :foreign_type]
+      super + [:primary_key, :dependent, :as, :through, :source, :source_type, :inverse_of, :counter_cache, :join_table, :foreign_type, :index_errors]
     end
 
     def self.valid_dependent_options
diff --git a/activerecord/lib/active_record/associations/builder/has_one.rb b/activerecord/lib/active_record/associations/builder/has_one.rb
index 64e9e6b334..9d64ae877b 100644
--- a/activerecord/lib/active_record/associations/builder/has_one.rb
+++ b/activerecord/lib/active_record/associations/builder/has_one.rb
@@ -1,4 +1,4 @@
-module ActiveRecord::Associations::Builder
+module ActiveRecord::Associations::Builder # :nodoc:
   class HasOne < SingularAssociation #:nodoc:
     def self.macro
       :has_one
@@ -17,5 +17,12 @@ module ActiveRecord::Associations::Builder
     def self.add_destroy_callbacks(model, reflection)
       super unless reflection.options[:through]
     end
+
+    def self.define_validations(model, reflection)
+      super
+      if reflection.options[:required]
+        model.validates_presence_of reflection.name, message: :required
+      end
+    end
   end
 end
diff --git a/activerecord/lib/active_record/associations/builder/singular_association.rb b/activerecord/lib/active_record/associations/builder/singular_association.rb
index 1369212837..58a9c8ff24 100644
--- a/activerecord/lib/active_record/associations/builder/singular_association.rb
+++ b/activerecord/lib/active_record/associations/builder/singular_association.rb
@@ -1,6 +1,6 @@
 # This class is inherited by the has_one and belongs_to association classes
 
-module ActiveRecord::Associations::Builder
+module ActiveRecord::Associations::Builder # :nodoc:
   class SingularAssociation < Association #:nodoc:
     def self.valid_options(options)
       super + [:dependent, :primary_key, :inverse_of, :required]
@@ -27,12 +27,5 @@ module ActiveRecord::Associations::Builder
         end
       CODE
     end
-
-    def self.define_validations(model, reflection)
-      super
-      if reflection.options[:required]
-        model.validates_presence_of reflection.name
-      end
-    end
   end
 end
diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
index f2c96e9a2a..f32dddb8f0 100644
--- a/activerecord/lib/active_record/associations/collection_association.rb
+++ b/activerecord/lib/active_record/associations/collection_association.rb
@@ -28,15 +28,21 @@ module ActiveRecord
       # Implements the reader method, e.g. foo.items for Foo.has_many :items
       def reader(force_reload = false)
         if force_reload
+          ActiveSupport::Deprecation.warn(<<-MSG.squish)
+            Passing an argument to force an association to reload is now
+            deprecated and will be removed in Rails 5.1. Please call `reload`
+            on the result collection proxy instead.
+          MSG
+
           klass.uncached { reload }
         elsif stale_target?
           reload
         end
 
-        if owner.new_record?
+        if null_scope?
           # Cache the proxy separately before the owner has an id
           # or else a post-save proxy will still lack the id
-          @new_record_proxy ||= CollectionProxy.create(klass, self)
+          @null_proxy ||= CollectionProxy.create(klass, self)
         else
           @proxy ||= CollectionProxy.create(klass, self)
         end
@@ -54,8 +60,10 @@ module ActiveRecord
             record.send(reflection.association_primary_key)
           end
         else
-          column  = "#{reflection.quoted_table_name}.#{reflection.association_primary_key}"
-          scope.pluck(column)
+          @association_ids ||= (
+            column = "#{reflection.quoted_table_name}.#{reflection.association_primary_key}"
+            scope.pluck(column)
+          )
         end
       end
 
@@ -63,7 +71,7 @@ module ActiveRecord
       def ids_writer(ids)
         pk_type = reflection.primary_key_type
         ids = Array(ids).reject(&:blank?)
-        ids.map! { |i| pk_type.type_cast_from_user(i) }
+        ids.map! { |i| pk_type.cast(i) }
         replace(klass.find(ids).index_by(&:id).values_at(*ids))
       end
 
@@ -129,6 +137,16 @@ module ActiveRecord
         first_nth_or_last(:last, *args)
       end
 
+      def take(n = nil)
+        if loaded?
+          n ? target.take(n) : target.first
+        else
+          scope.take(n).tap do |record|
+            set_inverse_instance record if record.is_a? ActiveRecord::Base
+          end
+        end
+      end
+
       def build(attributes = {}, &block)
         if attributes.is_a?(Array)
           attributes.collect { |attr| build(attr, &block) }
@@ -151,6 +169,7 @@ module ActiveRecord
       # be chained. Since << flattens its argument list and inserts each record,
       # +push+ and +concat+ behave identically.
       def concat(*records)
+        records = records.flatten
         if owner.new_record?
           load_target
           concat_records(records)
@@ -318,7 +337,8 @@ module ActiveRecord
       end
 
       # Returns true if the collections is not empty.
-      # Equivalent to +!collection.empty?+.
+      # If block given, loads all records and checks for one or more matches.
+      # Otherwise, equivalent to +!collection.empty?+.
       def any?
         if block_given?
           load_target.any? { |*block_args| yield(*block_args) }
@@ -328,7 +348,8 @@ module ActiveRecord
       end
 
       # Returns true if the collection has more than 1 record.
-      # Equivalent to +collection.size > 1+.
+      # If block given, loads all records and checks for two or more matches.
+      # Otherwise, equivalent to +collection.size > 1+.
       def many?
         if block_given?
           load_target.many? { |*block_args| yield(*block_args) }
@@ -357,6 +378,8 @@ module ActiveRecord
           replace_common_records_in_memory(other_array, original_target)
           if other_array != original_target
             transaction { replace_records(other_array, original_target) }
+          else
+            other_array
           end
         end
       end
@@ -417,13 +440,7 @@ module ActiveRecord
 
       private
       def get_records
-        if reflection.scope_chain.any?(&:any?) ||
-          scope.eager_loading? ||
-          klass.current_scope ||
-          klass.default_scopes.any?
-
-          return scope.to_a
-        end
+        return scope.to_a if skip_statement_cache?
 
         conn = klass.connection
         sc = reflection.association_scope_cache(conn, owner) do
@@ -549,7 +566,7 @@ module ActiveRecord
         def concat_records(records, should_raise = false)
           result = true
 
-          records.flatten.each do |record|
+          records.each do |record|
             raise_on_type_mismatch!(record)
             add_to_target(record) do |rec|
               result &&= insert_record(rec, true, should_raise) unless owner.new_record?
diff --git a/activerecord/lib/active_record/associations/collection_proxy.rb b/activerecord/lib/active_record/associations/collection_proxy.rb
index c22dc6e11e..fe693cfbb6 100644
--- a/activerecord/lib/active_record/associations/collection_proxy.rb
+++ b/activerecord/lib/active_record/associations/collection_proxy.rb
@@ -112,7 +112,7 @@ module ActiveRecord
       end
 
       # Finds an object in the collection responding to the +id+. Uses the same
-      # rules as <tt>ActiveRecord::Base.find</tt>. Returns <tt>ActiveRecord::RecordNotFound</tt>
+      # rules as ActiveRecord::Base.find. Returns ActiveRecord::RecordNotFound
       # error if the object cannot be found.
       #
       #   class Person < ActiveRecord::Base
@@ -127,7 +127,7 @@ module ActiveRecord
       #   #    ]
       #
       #   person.pets.find(1) # => #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>
-      #   person.pets.find(4) # => ActiveRecord::RecordNotFound: Couldn't find Pet with id=4
+      #   person.pets.find(4) # => ActiveRecord::RecordNotFound: Couldn't find Pet with 'id'=4
       #
       #   person.pets.find(2) { |pet| pet.name.downcase! }
       #   # => #<Pet id: 2, name: "fancy-fancy", person_id: 1>
@@ -171,27 +171,27 @@ module ActiveRecord
         @association.first(*args)
       end
 
-      # Same as +first+ except returns only the second record.
+      # Same as #first except returns only the second record.
       def second(*args)
         @association.second(*args)
       end
 
-      # Same as +first+ except returns only the third record.
+      # Same as #first except returns only the third record.
       def third(*args)
         @association.third(*args)
       end
 
-      # Same as +first+ except returns only the fourth record.
+      # Same as #first except returns only the fourth record.
       def fourth(*args)
         @association.fourth(*args)
       end
 
-      # Same as +first+ except returns only the fifth record.
+      # Same as #first except returns only the fifth record.
       def fifth(*args)
         @association.fifth(*args)
       end
 
-      # Same as +first+ except returns only the forty second record.
+      # Same as #first except returns only the forty second record.
       # Also known as accessing "the reddit".
       def forty_two(*args)
         @association.forty_two(*args)
@@ -227,6 +227,35 @@ module ActiveRecord
         @association.last(*args)
       end
 
+      # Gives a record (or N records if a parameter is supplied) from the collection
+      # using the same rules as <tt>ActiveRecord::Base.take</tt>.
+      #
+      #   class Person < ActiveRecord::Base
+      #     has_many :pets
+      #   end
+      #
+      #   person.pets
+      #   # => [
+      #   #       #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
+      #   #       #<Pet id: 2, name: "Spook", person_id: 1>,
+      #   #       #<Pet id: 3, name: "Choo-Choo", person_id: 1>
+      #   #    ]
+      #
+      #   person.pets.take # => #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>
+      #
+      #   person.pets.take(2)
+      #   # => [
+      #   #      #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
+      #   #      #<Pet id: 2, name: "Spook", person_id: 1>
+      #   #    ]
+      #
+      #   another_person_without.pets         # => []
+      #   another_person_without.pets.take    # => nil
+      #   another_person_without.pets.take(2) # => []
+      def take(n = nil)
+        @association.take(n)
+      end
+
       # Returns a new object of the collection type that has been instantiated
       # with +attributes+ and linked to this object, but have not yet been saved.
       # You can pass an array of attributes hashes, this will return an array
@@ -286,7 +315,7 @@ module ActiveRecord
         @association.create(attributes, &block)
       end
 
-      # Like +create+, except that if the record is invalid, raises an exception.
+      # Like #create, except that if the record is invalid, raises an exception.
       #
       #   class Person
       #     has_many :pets
@@ -303,8 +332,8 @@ module ActiveRecord
       end
 
       # Add one or more records to the collection by setting their foreign keys
-      # to the association's primary key. Since << flattens its argument list and
-      # inserts each record, +push+ and +concat+ behave identically. Returns +self+
+      # to the association's primary key. Since #<< flattens its argument list and
+      # inserts each record, +push+ and #concat behave identically. Returns +self+
       # so method calls may be chained.
       #
       #   class Person < ActiveRecord::Base
@@ -360,7 +389,7 @@ module ActiveRecord
       # specified by the +:dependent+ option. If no +:dependent+ option is given,
       # then it will follow the default strategy.
       #
-      # For +has_many :through+ associations, the default deletion strategy is
+      # For <tt>has_many :through</tt> associations, the default deletion strategy is
       # +:delete_all+.
       #
       # For +has_many+ associations, the default deletion strategy is +:nullify+.
@@ -395,7 +424,7 @@ module ActiveRecord
       #   #       #<Pet id: 3, name: "Choo-Choo", person_id: nil>
       #   #    ]
       #
-      # Both +has_many+ and +has_many :through+ dependencies default to the
+      # Both +has_many+ and <tt>has_many :through</tt> dependencies default to the
       # +:delete_all+ strategy if the +:dependent+ option is set to +:destroy+.
       # Records are not instantiated and callbacks will not be fired.
       #
@@ -414,7 +443,7 @@ module ActiveRecord
       #   person.pets.delete_all
       #
       #   Pet.find(1, 2, 3)
-      #   # => ActiveRecord::RecordNotFound
+      #   # => ActiveRecord::RecordNotFound: Couldn't find all Pets with 'id': (1, 2, 3)
       #
       # If it is set to <tt>:delete_all</tt>, all the objects are deleted
       # *without* calling their +destroy+ method.
@@ -434,7 +463,7 @@ module ActiveRecord
       #   person.pets.delete_all
       #
       #   Pet.find(1, 2, 3)
-      #   # => ActiveRecord::RecordNotFound
+      #   # => ActiveRecord::RecordNotFound: Couldn't find all Pets with 'id': (1, 2, 3)
       def delete_all(dependent = nil)
         @association.delete_all(dependent)
       end
@@ -466,15 +495,16 @@ module ActiveRecord
         @association.destroy_all
       end
 
-      # Deletes the +records+ supplied and removes them from the collection. For
-      # +has_many+ associations, the deletion is done according to the strategy
-      # specified by the <tt>:dependent</tt> option. Returns an array with the
+      # Deletes the +records+ supplied from the collection according to the strategy
+      # specified by the +:dependent+ option. If no +:dependent+ option is given,
+      # then it will follow the default strategy. Returns an array with the
       # deleted records.
       #
-      # If no <tt>:dependent</tt> option is given, then it will follow the default
-      # strategy. The default strategy is <tt>:nullify</tt>. This sets the foreign
-      # keys to <tt>NULL</tt>. For, +has_many+ <tt>:through</tt>, the default
-      # strategy is +delete_all+.
+      # For <tt>has_many :through</tt> associations, the default deletion strategy is
+      # +:delete_all+.
+      #
+      # For +has_many+ associations, the default deletion strategy is +:nullify+.
+      # This sets the foreign keys to +NULL+.
       #
       #   class Person < ActiveRecord::Base
       #     has_many :pets # dependent: :nullify option by default
@@ -527,7 +557,7 @@ module ActiveRecord
       #   # => [#<Pet id: 2, name: "Spook", person_id: 1>]
       #
       #   Pet.find(1, 3)
-      #   # => ActiveRecord::RecordNotFound: Couldn't find all Pets with IDs (1, 3)
+      #   # => ActiveRecord::RecordNotFound: Couldn't find all Pets with 'id': (1, 3)
       #
       # If it is set to <tt>:delete_all</tt>, all the +records+ are deleted
       # *without* calling their +destroy+ method.
@@ -555,7 +585,7 @@ module ActiveRecord
       #   #    ]
       #
       #   Pet.find(1)
-      #   # => ActiveRecord::RecordNotFound: Couldn't find Pet with id=1
+      #   # => ActiveRecord::RecordNotFound: Couldn't find Pet with 'id'=1
       #
       # You can pass +Fixnum+ or +String+ values, it finds the records
       # responding to the +id+ and executes delete on them.
@@ -619,7 +649,7 @@ module ActiveRecord
       #   person.pets.size  # => 0
       #   person.pets       # => []
       #
-      #   Pet.find(1, 2, 3) # => ActiveRecord::RecordNotFound: Couldn't find all Pets with IDs (1, 2, 3)
+      #   Pet.find(1, 2, 3) # => ActiveRecord::RecordNotFound: Couldn't find all Pets with 'id': (1, 2, 3)
       #
       # You can pass +Fixnum+ or +String+ values, it finds the records
       # responding to the +id+ and then deletes them from the database.
@@ -651,7 +681,7 @@ module ActiveRecord
       #   person.pets.size  # => 0
       #   person.pets       # => []
       #
-      #   Pet.find(4, 5, 6) # => ActiveRecord::RecordNotFound: Couldn't find all Pets with IDs (4, 5, 6)
+      #   Pet.find(4, 5, 6) # => ActiveRecord::RecordNotFound: Couldn't find all Pets with 'id': (4, 5, 6)
       def destroy(*records)
         @association.destroy(*records)
       end
@@ -776,7 +806,7 @@ module ActiveRecord
       #   person.pets.any?  # => false
       #
       #   person.pets << Pet.new(name: 'Snoop')
-      #   person.pets.count # => 0
+      #   person.pets.count # => 1
       #   person.pets.any?  # => true
       #
       # You can also pass a +block+ to define criteria. The behavior
@@ -851,7 +881,7 @@ module ActiveRecord
         !!@association.include?(record)
       end
 
-      def arel
+      def arel #:nodoc:
         scope.arel
       end
 
@@ -966,12 +996,15 @@ module ActiveRecord
       alias_method :append, :<<
 
       def prepend(*args)
-        raise NoMethodError, "prepend on association is not defined. Please use << or append"
+        raise NoMethodError, "prepend on association is not defined. Please use <<, push or append"
       end
 
       # Equivalent to +delete_all+. The difference is that returns +self+, instead
       # of an array with the deleted objects, so methods can be chained. See
       # +delete_all+ for more information.
+      # Note that because +delete_all+ removes records by directly
+      # running an SQL query into the database, the +updated_at+ column of
+      # the object is not changed.
       def clear
         delete_all
         self
diff --git a/activerecord/lib/active_record/associations/foreign_association.rb b/activerecord/lib/active_record/associations/foreign_association.rb
index fe48ecec29..3ceec0ee46 100644
--- a/activerecord/lib/active_record/associations/foreign_association.rb
+++ b/activerecord/lib/active_record/associations/foreign_association.rb
@@ -1,5 +1,5 @@
 module ActiveRecord::Associations
-  module ForeignAssociation
+  module ForeignAssociation # :nodoc:
     def foreign_key_present?
       if reflection.klass.primary_key
         owner.attribute_present?(reflection.active_record_primary_key)
diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index 2a782c06d0..a9f6aaafef 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -15,8 +15,15 @@ module ActiveRecord
 
         when :restrict_with_error
           unless empty?
-            record = klass.human_attribute_name(reflection.name).downcase
-            owner.errors.add(:base, :"restrict_dependent_destroy.many", record: record)
+            record = owner.class.human_attribute_name(reflection.name).downcase
+            message = owner.errors.generate_message(:base, :'restrict_dependent_destroy.many', record: record, raise: true) rescue nil
+            if message
+              ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+                The error key `:'restrict_dependent_destroy.many'` has been deprecated and will be removed in Rails 5.1.
+                Please use `:'restrict_dependent_destroy.has_many'` instead.
+              MESSAGE
+            end
+            owner.errors.add(:base, message || :'restrict_dependent_destroy.has_many', record: record)
             throw(:abort)
           end
 
@@ -43,7 +50,7 @@ module ActiveRecord
       end
 
       def empty?
-        if has_cached_counter?
+        if reflection.has_cached_counter?
           size.zero?
         else
           super
@@ -66,8 +73,8 @@ module ActiveRecord
         # If the collection is empty the target is set to an empty array and
         # the loaded flag is set to true as well.
         def count_records
-          count = if has_cached_counter?
-            owner._read_attribute cached_counter_attribute_name
+          count = if reflection.has_cached_counter?
+            owner._read_attribute reflection.counter_cache_column
           else
             scope.count
           end
@@ -80,56 +87,20 @@ module ActiveRecord
           [association_scope.limit_value, count].compact.min
         end
 
-        def has_cached_counter?(reflection = reflection())
-          owner.attribute_present?(cached_counter_attribute_name(reflection))
-        end
-
-        def cached_counter_attribute_name(reflection = reflection())
-          options[:counter_cache] || "#{reflection.name}_count"
-        end
-
         def update_counter(difference, reflection = reflection())
-          update_counter_in_database(difference, reflection)
-          update_counter_in_memory(difference, reflection)
-        end
-
-        def update_counter_in_database(difference, reflection = reflection())
-          if has_cached_counter?(reflection)
-            counter = cached_counter_attribute_name(reflection)
-            owner.class.update_counters(owner.id, counter => difference)
+          if reflection.has_cached_counter?
+            owner.increment!(reflection.counter_cache_column, difference)
           end
         end
 
         def update_counter_in_memory(difference, reflection = reflection())
-          if has_cached_counter?(reflection)
-            counter = cached_counter_attribute_name(reflection)
-            owner[counter] += difference
-            owner.send(:clear_attribute_changes, counter) # eww
+          if reflection.counter_must_be_updated_by_has_many?
+            counter = reflection.counter_cache_column
+            owner.increment(counter, difference)
+            owner.send(:clear_attribute_change, counter) # eww
           end
         end
 
-        # This shit is nasty. We need to avoid the following situation:
-        #
-        #   * An associated record is deleted via record.destroy
-        #   * Hence the callbacks run, and they find a belongs_to on the record with a
-        #     :counter_cache options which points back at our owner. So they update the
-        #     counter cache.
-        #   * In which case, we must make sure to *not* update the counter cache, or else
-        #     it will be decremented twice.
-        #
-        # Hence this method.
-        def inverse_updates_counter_cache?(reflection = reflection())
-          counter_name = cached_counter_attribute_name(reflection)
-          inverse_updates_counter_named?(counter_name, reflection)
-        end
-
-        def inverse_updates_counter_named?(counter_name, reflection = reflection())
-          reflection.klass._reflections.values.any? { |inverse_reflection|
-            inverse_reflection.belongs_to? &&
-            inverse_reflection.counter_cache_column == counter_name
-          }
-        end
-
         def delete_count(method, scope)
           if method == :delete_all
             scope.delete_all
@@ -147,7 +118,7 @@ module ActiveRecord
         def delete_records(records, method)
           if method == :destroy
             records.each(&:destroy!)
-            update_counter(-records.length) unless inverse_updates_counter_cache?
+            update_counter(-records.length) unless reflection.inverse_updates_counter_cache?
           else
             scope = self.scope.where(reflection.klass.primary_key => records)
             update_counter(-delete_count(method, scope))
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index f1e784d771..deb0f8c9f5 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -38,12 +38,10 @@ module ActiveRecord
       def insert_record(record, validate = true, raise = false)
         ensure_not_nested
 
-        if record.new_record?
-          if raise
-            record.save!(:validate => validate)
-          else
-            return unless record.save(:validate => validate)
-          end
+        if raise
+          record.save!(:validate => validate)
+        else
+          return unless record.save(:validate => validate)
         end
 
         save_through_record(record)
@@ -112,7 +110,7 @@ module ActiveRecord
         def update_through_counter?(method)
           case method
           when :destroy
-            !inverse_updates_counter_cache?(through_reflection)
+            !through_reflection.inverse_updates_counter_cache?
           when :nullify
             false
           else
@@ -143,7 +141,7 @@ module ActiveRecord
               stmt.from scope.klass.arel_table
               stmt.wheres = arel.constraints
 
-              count = scope.klass.connection.delete(stmt, 'SQL', scope.bind_values)
+              count = scope.klass.connection.delete(stmt, 'SQL', scope.bound_attributes)
             end
           when :nullify
             count = scope.update_all(source_reflection.foreign_key => nil)
@@ -160,9 +158,9 @@ module ActiveRecord
 
           if through_reflection.collection? && update_through_counter?(method)
             update_counter(-count, through_reflection)
+          else
+            update_counter(-count)
           end
-
-          update_counter(-count)
         end
 
         def through_records_for(record)
diff --git a/activerecord/lib/active_record/associations/has_one_association.rb b/activerecord/lib/active_record/associations/has_one_association.rb
index 41a75b820e..0fe9b2e81b 100644
--- a/activerecord/lib/active_record/associations/has_one_association.rb
+++ b/activerecord/lib/active_record/associations/has_one_association.rb
@@ -1,5 +1,5 @@
 module ActiveRecord
-  # = Active Record Belongs To Has One Association
+  # = Active Record Has One Association
   module Associations
     class HasOneAssociation < SingularAssociation #:nodoc:
       include ForeignAssociation
@@ -11,8 +11,15 @@ module ActiveRecord
 
         when :restrict_with_error
           if load_target
-            record = klass.human_attribute_name(reflection.name).downcase
-            owner.errors.add(:base, :"restrict_dependent_destroy.one", record: record)
+            record = owner.class.human_attribute_name(reflection.name).downcase
+            message = owner.errors.generate_message(:base, :'restrict_dependent_destroy.one', record: record, raise: true) rescue nil
+            if message
+              ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+                The error key `:'restrict_dependent_destroy.one'` has been deprecated and will be removed in Rails 5.1.
+                Please use `:'restrict_dependent_destroy.has_one'` instead.
+              MESSAGE
+            end
+            owner.errors.add(:base, message || :'restrict_dependent_destroy.has_one', record: record)
             throw(:abort)
           end
 
@@ -58,7 +65,7 @@ module ActiveRecord
             when :destroy
               target.destroy
             when :nullify
-              target.update_columns(reflection.foreign_key => nil)
+              target.update_columns(reflection.foreign_key => nil) if target.persisted?
           end
         end
       end
diff --git a/activerecord/lib/active_record/associations/join_dependency.rb b/activerecord/lib/active_record/associations/join_dependency.rb
index 4b75370171..0e98a3b3a4 100644
--- a/activerecord/lib/active_record/associations/join_dependency.rb
+++ b/activerecord/lib/active_record/associations/join_dependency.rb
@@ -131,9 +131,9 @@ module ActiveRecord
       def instantiate(result_set, aliases)
         primary_key = aliases.column_alias(join_root, join_root.primary_key)
 
-        seen = Hash.new { |h,parent_klass|
-          h[parent_klass] = Hash.new { |i,parent_id|
-            i[parent_id] = Hash.new { |j,child_klass| j[child_klass] = {} }
+        seen = Hash.new { |i, object_id|
+          i[object_id] = Hash.new { |j, child_class|
+            j[child_class] = {}
           }
         }
 
@@ -150,7 +150,8 @@ module ActiveRecord
 
         message_bus.instrument('instantiation.active_record', payload) do
           result_set.each { |row_hash|
-            parent = parents[row_hash[primary_key]] ||= join_root.instantiate(row_hash, column_aliases)
+            parent_key = primary_key ? row_hash[primary_key] : row_hash
+            parent = parents[parent_key] ||= join_root.instantiate(row_hash, column_aliases)
             construct(parent, join_root, row_hash, result_set, seen, model_cache, aliases)
           }
         end
@@ -232,32 +233,34 @@ module ActiveRecord
       end
 
       def construct(ar_parent, parent, row, rs, seen, model_cache, aliases)
-        primary_id  = ar_parent.id
+        return if ar_parent.nil?
 
         parent.children.each do |node|
           if node.reflection.collection?
             other = ar_parent.association(node.reflection.name)
             other.loaded!
-          else
-            if ar_parent.association_cache.key?(node.reflection.name)
-              model = ar_parent.association(node.reflection.name).target
-              construct(model, node, row, rs, seen, model_cache, aliases)
-              next
-            end
+          elsif ar_parent.association_cached?(node.reflection.name)
+            model = ar_parent.association(node.reflection.name).target
+            construct(model, node, row, rs, seen, model_cache, aliases)
+            next
           end
 
           key = aliases.column_alias(node, node.primary_key)
           id = row[key]
-          next if id.nil?
+          if id.nil?
+            nil_association = ar_parent.association(node.reflection.name)
+            nil_association.loaded!
+            next
+          end
 
-          model = seen[parent.base_klass][primary_id][node.base_klass][id]
+          model = seen[ar_parent.object_id][node.base_klass][id]
 
           if model
             construct(model, node, row, rs, seen, model_cache, aliases)
           else
             model = construct_model(ar_parent, node, row, model_cache, id, aliases)
             model.readonly!
-            seen[parent.base_klass][primary_id][node.base_klass][id] = model
+            seen[ar_parent.object_id][node.base_klass][id] = model
             construct(model, node, row, rs, seen, model_cache, aliases)
           end
         end
diff --git a/activerecord/lib/active_record/associations/join_dependency/join_association.rb b/activerecord/lib/active_record/associations/join_dependency/join_association.rb
index c1ef86a95b..a6ad09a38a 100644
--- a/activerecord/lib/active_record/associations/join_dependency/join_association.rb
+++ b/activerecord/lib/active_record/associations/join_dependency/join_association.rb
@@ -25,7 +25,7 @@ module ActiveRecord
 
         def join_constraints(foreign_table, foreign_klass, node, join_type, tables, scope_chain, chain)
           joins         = []
-          bind_values   = []
+          binds         = []
           tables        = tables.reverse
 
           scope_chain_index = 0
@@ -66,7 +66,7 @@ module ActiveRecord
             end
 
             if rel && !rel.arel.constraints.empty?
-              bind_values.concat rel.bind_values
+              binds += rel.bound_attributes
               constraint = constraint.and rel.arel.constraints
             end
 
@@ -75,7 +75,7 @@ module ActiveRecord
               column = klass.columns_hash[reflection.type.to_s]
 
               substitute = klass.connection.substitute_at(column)
-              bind_values.push [column, value]
+              binds << Relation::QueryAttribute.new(column.name, value, klass.type_for_attribute(column.name))
               constraint = constraint.and table[reflection.type].eq substitute
             end
 
@@ -85,7 +85,7 @@ module ActiveRecord
             foreign_table, foreign_klass = table, klass
           end
 
-          JoinInformation.new joins, bind_values
+          JoinInformation.new joins, binds
         end
 
         #  Builds equality condition.
diff --git a/activerecord/lib/active_record/associations/preloader.rb b/activerecord/lib/active_record/associations/preloader.rb
index 4358f3b581..ecf6fb8643 100644
--- a/activerecord/lib/active_record/associations/preloader.rb
+++ b/activerecord/lib/active_record/associations/preloader.rb
@@ -10,13 +10,13 @@ module ActiveRecord
     #   end
     #
     #   class Book < ActiveRecord::Base
-    #     # columns: title, sales
+    #     # columns: title, sales, author_id
     #   end
     #
     # When you load an author with all associated books Active Record will make
     # multiple queries like this:
     #
-    #   Author.includes(:books).where(:name => ['bell hooks', 'Homer').to_a
+    #   Author.includes(:books).where(name: ['bell hooks', 'Homer']).to_a
     #
     #   => SELECT `authors`.* FROM `authors` WHERE `name` IN ('bell hooks', 'Homer')
     #   => SELECT `books`.* FROM `books` WHERE `author_id` IN (2, 5)
@@ -54,6 +54,8 @@ module ActiveRecord
         autoload :BelongsTo,           'active_record/associations/preloader/belongs_to'
       end
 
+      NULL_RELATION = Struct.new(:values, :where_clause, :joins_values).new({}, Relation::WhereClause.empty, [])
+
       # Eager loads the named associations for the given Active Record record(s).
       #
       # In this description, 'association name' shall refer to the name passed
@@ -88,9 +90,6 @@ module ActiveRecord
       #   [ :books, :author ]
       #   { author: :avatar }
       #   [ :books, { author: :avatar } ]
-
-      NULL_RELATION = Struct.new(:values, :bind_values).new({}, [])
-
       def preload(records, associations, preload_scope = nil)
         records       = Array.wrap(records).compact.uniq
         associations  = Array.wrap(associations)
@@ -107,6 +106,7 @@ module ActiveRecord
 
       private
 
+      # Loads all the given data into +records+ for the +association+.
       def preloaders_on(association, records, scope)
         case association
         when Hash
@@ -116,7 +116,7 @@ module ActiveRecord
         when String
           preloaders_for_one(association.to_sym, records, scope)
         else
-          raise ArgumentError, "#{association.inspect} was not recognised for preload"
+          raise ArgumentError, "#{association.inspect} was not recognized for preload"
         end
       end
 
@@ -132,6 +132,11 @@ module ActiveRecord
         }
       end
 
+      # Loads all the given data into +records+ for a singular +association+.
+      #
+      # Functions by instantiating a preloader class such as Preloader::HasManyThrough and
+      # call the +run+ method for each passed in class in the +records+ argument.
+      #
       # Not all records have the same class, so group then preload group on the reflection
       # itself so that if various subclass share the same association then we do not split
       # them unnecessarily
@@ -160,7 +165,7 @@ module ActiveRecord
         h
       end
 
-      class AlreadyLoaded
+      class AlreadyLoaded # :nodoc:
         attr_reader :owners, :reflection
 
         def initialize(klass, owners, reflection, preload_scope)
@@ -175,12 +180,16 @@ module ActiveRecord
         end
       end
 
-      class NullPreloader
+      class NullPreloader # :nodoc:
         def self.new(klass, owners, reflection, preload_scope); self; end
         def self.run(preloader); end
         def self.preloaded_records; []; end
       end
 
+      # Returns a class containing the logic needed to load preload the data
+      # and attach it to a relation. For example +Preloader::Association+ or
+      # +Preloader::HasManyThrough+. The class returned implements a `run` method
+      # that accepts a preloader.
       def preloader_for(reflection, owners, rhs_klass)
         return NullPreloader unless rhs_klass
 
diff --git a/activerecord/lib/active_record/associations/preloader/association.rb b/activerecord/lib/active_record/associations/preloader/association.rb
index afcaa5d55a..29dd0643d6 100644
--- a/activerecord/lib/active_record/associations/preloader/association.rb
+++ b/activerecord/lib/active_record/associations/preloader/association.rb
@@ -12,7 +12,6 @@ module ActiveRecord
           @preload_scope = preload_scope
           @model         = owners.first && owners.first.class
           @scope         = nil
-          @owners_by_key = nil
           @preloaded_records = []
         end
 
@@ -56,18 +55,6 @@ module ActiveRecord
           raise NotImplementedError
         end
 
-        def owners_by_key
-          @owners_by_key ||= if key_conversion_required?
-                               owners.group_by do |owner|
-                                 owner[owner_key_name].to_s
-                               end
-                             else
-                               owners.group_by do |owner|
-                                 owner[owner_key_name]
-                               end
-                             end
-        end
-
         def options
           reflection.options
         end
@@ -75,53 +62,54 @@ module ActiveRecord
         private
 
         def associated_records_by_owner(preloader)
-          owners_map = owners_by_key
-          owner_keys = owners_map.keys.compact
-
-          # Each record may have multiple owners, and vice-versa
-          records_by_owner = owners.each_with_object({}) do |owner,h|
-            h[owner] = []
+          records = load_records
+          owners.each_with_object({}) do |owner, result|
+            result[owner] = records[convert_key(owner[owner_key_name])] || []
           end
+        end
 
-          if owner_keys.any?
-            # Some databases impose a limit on the number of ids in a list (in Oracle it's 1000)
-            # Make several smaller queries if necessary or make one query if the adapter supports it
-            sliced  = owner_keys.each_slice(klass.connection.in_clause_length || owner_keys.size)
-
-            records = load_slices sliced
-            records.each do |record, owner_key|
-              owners_map[owner_key].each do |owner|
-                records_by_owner[owner] << record
-              end
+        def owner_keys
+          unless defined?(@owner_keys)
+            @owner_keys = owners.map do |owner|
+              owner[owner_key_name]
             end
+            @owner_keys.uniq!
+            @owner_keys.compact!
           end
-
-          records_by_owner
+          @owner_keys
         end
 
         def key_conversion_required?
-          association_key_type != owner_key_type
+          @key_conversion_required ||= association_key_type != owner_key_type
+        end
+
+        def convert_key(key)
+          if key_conversion_required?
+            key.to_s
+          else
+            key
+          end
         end
 
         def association_key_type
-          @klass.column_for_attribute(association_key_name).type
+          @klass.type_for_attribute(association_key_name.to_s).type
         end
 
         def owner_key_type
-          @model.column_for_attribute(owner_key_name).type
+          @model.type_for_attribute(owner_key_name.to_s).type
         end
 
-        def load_slices(slices)
-          @preloaded_records = slices.flat_map { |slice|
+        def load_records
+          return {} if owner_keys.empty?
+          # Some databases impose a limit on the number of ids in a list (in Oracle it's 1000)
+          # Make several smaller queries if necessary or make one query if the adapter supports it
+          slices  = owner_keys.each_slice(klass.connection.in_clause_length || owner_keys.size)
+          @preloaded_records = slices.flat_map do |slice|
             records_for(slice)
-          }
-
-          @preloaded_records.map { |record|
-            key = record[association_key_name]
-            key = key.to_s if key_conversion_required?
-
-            [record, key]
-          }
+          end
+          @preloaded_records.group_by do |record| 
+            convert_key(record[association_key_name])
+          end
         end
 
         def reflection_scope
@@ -131,18 +119,21 @@ module ActiveRecord
         def build_scope
           scope = klass.unscoped
 
-          values         = reflection_scope.values
-          reflection_binds = reflection_scope.bind_values
+          values = reflection_scope.values
           preload_values = preload_scope.values
-          preload_binds  = preload_scope.bind_values
 
-          scope.where_values      = Array(values[:where])      + Array(preload_values[:where])
+          scope.where_clause = reflection_scope.where_clause + preload_scope.where_clause
           scope.references_values = Array(values[:references]) + Array(preload_values[:references])
-          scope.bind_values       = (reflection_binds + preload_binds)
 
-          scope._select!   preload_values[:select] || values[:select] || table[Arel.star]
+          if preload_values[:select] || values[:select]
+            scope._select!(preload_values[:select] || values[:select])
+          end
           scope.includes! preload_values[:includes] || values[:includes]
-          scope.joins! preload_values[:joins] || values[:joins]
+          if preload_scope.joins_values.any?
+            scope.joins!(preload_scope.joins_values)
+          else
+            scope.joins!(reflection_scope.joins_values)
+          end
           scope.order! preload_values[:order] || values[:order]
 
           if preload_values[:readonly] || values[:readonly]
@@ -153,7 +144,7 @@ module ActiveRecord
             scope.where!(klass.table_name => { reflection.type => model.base_class.sti_name })
           end
 
-          scope.unscope_values = Array(values[:unscope])
+          scope.unscope_values = Array(values[:unscope]) + Array(preload_values[:unscope])
           klass.default_scoped.merge(scope)
         end
       end
diff --git a/activerecord/lib/active_record/associations/preloader/through_association.rb b/activerecord/lib/active_record/associations/preloader/through_association.rb
index 12bf3ef138..56aa23b173 100644
--- a/activerecord/lib/active_record/associations/preloader/through_association.rb
+++ b/activerecord/lib/active_record/associations/preloader/through_association.rb
@@ -78,10 +78,9 @@ module ActiveRecord
           if options[:source_type]
             scope.where! reflection.foreign_type => options[:source_type]
           else
-            unless reflection_scope.where_values.empty?
+            unless reflection_scope.where_clause.empty?
               scope.includes_values = Array(reflection_scope.values[:includes] || options[:source])
-              scope.where_values    = reflection_scope.values[:where]
-              scope.bind_values     = reflection_scope.bind_values
+              scope.where_clause = reflection_scope.where_clause
             end
 
             scope.references! reflection_scope.values[:references]
diff --git a/activerecord/lib/active_record/associations/singular_association.rb b/activerecord/lib/active_record/associations/singular_association.rb
index c44242a0f0..c7cc48ba16 100644
--- a/activerecord/lib/active_record/associations/singular_association.rb
+++ b/activerecord/lib/active_record/associations/singular_association.rb
@@ -3,7 +3,13 @@ module ActiveRecord
     class SingularAssociation < Association #:nodoc:
       # Implements the reader method, e.g. foo.bar for Foo.has_one :bar
       def reader(force_reload = false)
-        if force_reload
+        if force_reload && klass
+          ActiveSupport::Deprecation.warn(<<-MSG.squish)
+            Passing an argument to force an association to reload is now
+            deprecated and will be removed in Rails 5.1. Please call `reload`
+            on the parent object instead.
+          MSG
+
           klass.uncached { reload }
         elsif !loaded? || stale_target?
           reload
@@ -39,13 +45,7 @@ module ActiveRecord
         end
 
         def get_records
-          if reflection.scope_chain.any?(&:any?) ||
-              scope.eager_loading? ||
-              klass.current_scope ||
-              klass.default_scopes.any?
-
-            return scope.limit(1).to_a
-          end
+          return scope.limit(1).to_a if skip_statement_cache?
 
           conn = klass.connection
           sc = reflection.association_scope_cache(conn, owner) do
diff --git a/activerecord/lib/active_record/associations/through_association.rb b/activerecord/lib/active_record/associations/through_association.rb
index 09828dbd9b..d0ec3e8015 100644
--- a/activerecord/lib/active_record/associations/through_association.rb
+++ b/activerecord/lib/active_record/associations/through_association.rb
@@ -15,12 +15,6 @@ module ActiveRecord
           scope = super
           reflection.chain.drop(1).each do |reflection|
             relation = reflection.klass.all
-
-            reflection_scope = reflection.scope
-            if reflection_scope && reflection_scope.arity.zero?
-              relation.merge!(reflection_scope)
-            end
-
             scope.merge!(
               relation.except(:select, :create_with, :includes, :preload, :joins, :eager_load)
             )
@@ -33,7 +27,7 @@ module ActiveRecord
         # Construct attributes for :through pointing to owner and associate. This is used by the
         # methods which create and delete records on the association.
         #
-        # We only support indirectly modifying through associations which has a belongs_to source.
+        # We only support indirectly modifying through associations which have a belongs_to source.
         # This is the "has_many :tags, through: :taggings" situation, where the join model
         # typically has a belongs_to on both side. In other words, associations which could also
         # be represented as has_and_belongs_to_many associations.
@@ -82,13 +76,21 @@ module ActiveRecord
 
         def ensure_mutable
           unless source_reflection.belongs_to?
-            raise HasManyThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection)
+            if reflection.has_one?
+              raise HasOneThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection)
+            else
+              raise HasManyThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection)
+            end
           end
         end
 
         def ensure_not_nested
           if reflection.nested?
-            raise HasManyThroughNestedAssociationsAreReadonly.new(owner, reflection)
+            if reflection.has_one?
+              raise HasOneThroughNestedAssociationsAreReadonly.new(owner, reflection)
+            else
+              raise HasManyThroughNestedAssociationsAreReadonly.new(owner, reflection)
+            end
           end
         end
 
diff --git a/activerecord/lib/active_record/attribute.rb b/activerecord/lib/active_record/attribute.rb
index 51e4fae62e..3c4c8f10ec 100644
--- a/activerecord/lib/active_record/attribute.rb
+++ b/activerecord/lib/active_record/attribute.rb
@@ -5,8 +5,8 @@ module ActiveRecord
         FromDatabase.new(name, value, type)
       end
 
-      def from_user(name, value, type)
-        FromUser.new(name, value, type)
+      def from_user(name, value, type, original_attribute = nil)
+        FromUser.new(name, value, type, original_attribute)
       end
 
       def with_cast_value(name, value, type)
@@ -26,36 +26,46 @@ module ActiveRecord
 
     # This method should not be called directly.
     # Use #from_database or #from_user
-    def initialize(name, value_before_type_cast, type)
+    def initialize(name, value_before_type_cast, type, original_attribute = nil)
       @name = name
       @value_before_type_cast = value_before_type_cast
       @type = type
+      @original_attribute = original_attribute
     end
 
     def value
       # `defined?` is cheaper than `||=` when we get back falsy values
-      @value = original_value unless defined?(@value)
+      @value = type_cast(value_before_type_cast) unless defined?(@value)
       @value
     end
 
     def original_value
-      type_cast(value_before_type_cast)
+      if assigned?
+        original_attribute.original_value
+      else
+        type_cast(value_before_type_cast)
+      end
     end
 
     def value_for_database
-      type.type_cast_for_database(value)
+      type.serialize(value)
+    end
+
+    def changed?
+      changed_from_assignment? || changed_in_place?
     end
 
-    def changed_from?(old_value)
-      type.changed?(old_value, value, value_before_type_cast)
+    def changed_in_place?
+      has_been_read? && type.changed_in_place?(original_value_for_database, value)
     end
 
-    def changed_in_place_from?(old_value)
-      type.changed_in_place?(old_value, value)
+    def forgetting_assignment
+      with_value_from_database(value_for_database)
     end
 
     def with_value_from_user(value)
-      self.class.from_user(name, value, type)
+      type.assert_valid_value(value)
+      self.class.from_user(name, value, type, self)
     end
 
     def with_value_from_database(value)
@@ -66,6 +76,10 @@ module ActiveRecord
       self.class.with_cast_value(name, value, type)
     end
 
+    def with_type(type)
+      self.class.new(name, value_before_type_cast, type, original_attribute)
+    end
+
     def type_cast(*)
       raise NotImplementedError
     end
@@ -78,30 +92,62 @@ module ActiveRecord
       false
     end
 
+    def has_been_read?
+      defined?(@value)
+    end
+
     def ==(other)
       self.class == other.class &&
         name == other.name &&
         value_before_type_cast == other.value_before_type_cast &&
         type == other.type
     end
+    alias eql? ==
+
+    def hash
+      [self.class, name, value_before_type_cast, type].hash
+    end
 
     protected
 
+    attr_reader :original_attribute
+    alias_method :assigned?, :original_attribute
+
     def initialize_dup(other)
       if defined?(@value) && @value.duplicable?
         @value = @value.dup
       end
     end
 
+    def changed_from_assignment?
+      assigned? && type.changed?(original_value, value, value_before_type_cast)
+    end
+
+    def original_value_for_database
+      if assigned?
+        original_attribute.original_value_for_database
+      else
+        _original_value_for_database
+      end
+    end
+
+    def _original_value_for_database
+      value_for_database
+    end
+
     class FromDatabase < Attribute # :nodoc:
       def type_cast(value)
-        type.type_cast_from_database(value)
+        type.deserialize(value)
+      end
+
+      def _original_value_for_database
+        value_before_type_cast
       end
     end
 
     class FromUser < Attribute # :nodoc:
       def type_cast(value)
-        type.type_cast_from_user(value)
+        type.cast(value)
       end
 
       def came_from_user?
@@ -128,6 +174,10 @@ module ActiveRecord
         nil
       end
 
+      def with_type(type)
+        self.class.with_cast_value(name, nil, type)
+      end
+
       def with_value_from_database(value)
         raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{name}`"
       end
@@ -152,6 +202,6 @@ module ActiveRecord
         false
       end
     end
-    private_constant :FromDatabase, :FromUser, :Null, :Uninitialized
+    private_constant :FromDatabase, :FromUser, :Null, :Uninitialized, :WithCastValue
   end
 end
diff --git a/activerecord/lib/active_record/attribute/user_provided_default.rb b/activerecord/lib/active_record/attribute/user_provided_default.rb
new file mode 100644
index 0000000000..6dbd92ce28
--- /dev/null
+++ b/activerecord/lib/active_record/attribute/user_provided_default.rb
@@ -0,0 +1,23 @@
+require 'active_record/attribute'
+
+module ActiveRecord
+  class Attribute # :nodoc:
+    class UserProvidedDefault < FromUser # :nodoc:
+      def initialize(name, value, type, database_default)
+        super(name, value, type, database_default)
+      end
+
+      def type_cast(value)
+        if value.is_a?(Proc)
+          super(value.call)
+        else
+          super
+        end
+      end
+
+      def with_type(type)
+        self.class.new(name, value_before_type_cast, type, original_attribute)
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_assignment.rb b/activerecord/lib/active_record/attribute_assignment.rb
index bf64830417..a6d81c82b4 100644
--- a/activerecord/lib/active_record/attribute_assignment.rb
+++ b/activerecord/lib/active_record/attribute_assignment.rb
@@ -3,61 +3,38 @@ require 'active_model/forbidden_attributes_protection'
 module ActiveRecord
   module AttributeAssignment
     extend ActiveSupport::Concern
-    include ActiveModel::ForbiddenAttributesProtection
-
-    # Allows you to set all the attributes by passing in a hash of attributes with
-    # keys matching the attribute names (which again matches the column names).
-    #
-    # If the passed hash responds to <tt>permitted?</tt> method and the return value
-    # of this method is +false+ an <tt>ActiveModel::ForbiddenAttributesError</tt>
-    # exception is raised.
-    #
-    #   cat = Cat.new(name: "Gorby", status: "yawning")
-    #   cat.attributes # =>  { "name" => "Gorby", "status" => "yawning", "created_at" => nil, "updated_at" => nil}
-    #   cat.assign_attributes(status: "sleeping")
-    #   cat.attributes # =>  { "name" => "Gorby", "status" => "sleeping", "created_at" => nil, "updated_at" => nil }
-    #
-    # New attributes will be persisted in the database when the object is saved.
-    #
-    # Aliased to <tt>attributes=</tt>.
-    def assign_attributes(new_attributes)
-      if !new_attributes.respond_to?(:stringify_keys)
-        raise ArgumentError, "When assigning attributes, you must pass a hash as an argument."
-      end
-      return if new_attributes.blank?
+    include ActiveModel::AttributeAssignment
+
+    # Alias for ActiveModel::AttributeAssignment#assign_attributes. See ActiveModel::AttributeAssignment.
+    def attributes=(attributes)
+      assign_attributes(attributes)
+    end
 
-      attributes                  = new_attributes.stringify_keys
-      multi_parameter_attributes  = []
-      nested_parameter_attributes = []
+    private
 
-      attributes = sanitize_for_mass_assignment(attributes)
+    def _assign_attributes(attributes) # :nodoc:
+      multi_parameter_attributes  = {}
+      nested_parameter_attributes = {}
 
       attributes.each do |k, v|
         if k.include?("(")
-          multi_parameter_attributes << [ k, v ]
+          multi_parameter_attributes[k] = attributes.delete(k)
         elsif v.is_a?(Hash)
-          nested_parameter_attributes << [ k, v ]
-        else
-          _assign_attribute(k, v)
+          nested_parameter_attributes[k] = attributes.delete(k)
         end
       end
+      super(attributes)
 
       assign_nested_parameter_attributes(nested_parameter_attributes) unless nested_parameter_attributes.empty?
       assign_multiparameter_attributes(multi_parameter_attributes) unless multi_parameter_attributes.empty?
     end
 
-    alias attributes= assign_attributes
-
-    private
-
-    def _assign_attribute(k, v)
-      public_send("#{k}=", v)
-    rescue NoMethodError
-      if respond_to?("#{k}=")
-        raise
-      else
-        raise UnknownAttributeError.new(self, k)
-      end
+    # Tries to assign given value to given attribute.
+    # In case of an error, re-raises with the ActiveRecord constant.
+    def _assign_attribute(k, v) # :nodoc:
+      super
+    rescue ActiveModel::UnknownAttributeError
+      raise UnknownAttributeError.new(self, k)
     end
 
     # Assign any deferred nested attributes after the base attributes have been set.
@@ -81,7 +58,12 @@ module ActiveRecord
       errors = []
       callstack.each do |name, values_with_empty_parameters|
         begin
-          send("#{name}=", MultiparameterAttribute.new(self, name, values_with_empty_parameters).read_value)
+          if values_with_empty_parameters.each_value.all?(&:nil?)
+            values = nil
+          else
+            values = values_with_empty_parameters
+          end
+          send("#{name}=", values)
         rescue => ex
           errors << AttributeAssignmentError.new("error on assignment #{values_with_empty_parameters.values.inspect} to #{name} (#{ex.message})", ex, name)
         end
@@ -113,100 +95,5 @@ module ActiveRecord
     def find_parameter_position(multiparameter_name)
       multiparameter_name.scan(/\(([0-9]*).*\)/).first.first.to_i
     end
-
-    class MultiparameterAttribute #:nodoc:
-      attr_reader :object, :name, :values, :cast_type
-
-      def initialize(object, name, values)
-        @object = object
-        @name   = name
-        @values = values
-      end
-
-      def read_value
-        return if values.values.compact.empty?
-
-        @cast_type = object.type_for_attribute(name)
-        klass = cast_type.klass
-
-        if klass == Time
-          read_time
-        elsif klass == Date
-          read_date
-        else
-          read_other
-        end
-      end
-
-      private
-
-      def instantiate_time_object(set_values)
-        if object.class.send(:create_time_zone_conversion_attribute?, name, cast_type)
-          Time.zone.local(*set_values)
-        else
-          Time.send(object.class.default_timezone, *set_values)
-        end
-      end
-
-      def read_time
-        # If column is a :time (and not :date or :datetime) there is no need to validate if
-        # there are year/month/day fields
-        if cast_type.type == :time
-          # if the column is a time set the values to their defaults as January 1, 1970, but only if they're nil
-          { 1 => 1970, 2 => 1, 3 => 1 }.each do |key,value|
-            values[key] ||= value
-          end
-        else
-          # else column is a timestamp, so if Date bits were not provided, error
-          validate_required_parameters!([1,2,3])
-
-          # If Date bits were provided but blank, then return nil
-          return if blank_date_parameter?
-        end
-
-        max_position = extract_max_param(6)
-        set_values   = values.values_at(*(1..max_position))
-        # If Time bits are not there, then default to 0
-        (3..5).each { |i| set_values[i] = set_values[i].presence || 0 }
-        instantiate_time_object(set_values)
-      end
-
-      def read_date
-        return if blank_date_parameter?
-        set_values = values.values_at(1,2,3)
-        begin
-          Date.new(*set_values)
-        rescue ArgumentError # if Date.new raises an exception on an invalid date
-          instantiate_time_object(set_values).to_date # we instantiate Time object and convert it back to a date thus using Time's logic in handling invalid dates
-        end
-      end
-
-      def read_other
-        max_position = extract_max_param
-        positions    = (1..max_position)
-        validate_required_parameters!(positions)
-
-        values.slice(*positions)
-      end
-
-      # Checks whether some blank date parameter exists. Note that this is different
-      # than the validate_required_parameters! method, since it just checks for blank
-      # positions instead of missing ones, and does not raise in case one blank position
-      # exists. The caller is responsible to handle the case of this returning true.
-      def blank_date_parameter?
-        (1..3).any? { |position| values[position].blank? }
-      end
-
-      # If some position is not provided, it errors out a missing parameter exception.
-      def validate_required_parameters!(positions)
-        if missing_parameter = positions.detect { |position| !values.key?(position) }
-          raise ArgumentError.new("Missing Parameter - #{name}(#{missing_parameter})")
-        end
-      end
-
-      def extract_max_param(upper_cap = 100)
-        [values.keys.max, upper_cap].min
-      end
-    end
   end
 end
diff --git a/activerecord/lib/active_record/attribute_decorators.rb b/activerecord/lib/active_record/attribute_decorators.rb
index 5b96623b6e..7d0ae32411 100644
--- a/activerecord/lib/active_record/attribute_decorators.rb
+++ b/activerecord/lib/active_record/attribute_decorators.rb
@@ -15,7 +15,7 @@ module ActiveRecord
       end
 
       def decorate_matching_attribute_types(matcher, decorator_name, &block)
-        clear_caches_calculated_from_columns
+        reload_schema_from_cache
         decorator_name = decorator_name.to_s
 
         # Create new hashes so we don't modify parent classes
@@ -24,10 +24,11 @@ module ActiveRecord
 
       private
 
-      def add_user_provided_columns(*)
-        super.map do |column|
-          decorated_type = attribute_type_decorations.apply(column.name, column.cast_type)
-          column.with_type(decorated_type)
+      def load_schema!
+        super
+        attribute_types.each do |name, type|
+          decorated_type = attribute_type_decorations.apply(name, type)
+          define_attribute(name, decorated_type)
         end
       end
     end
diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index 8f165fb1dc..cbdd4950a6 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -1,7 +1,7 @@
 require 'active_support/core_ext/enumerable'
 require 'active_support/core_ext/string/filters'
 require 'mutex_m'
-require 'thread_safe'
+require 'concurrent'
 
 module ActiveRecord
   # = Active Record Attribute Methods
@@ -37,12 +37,12 @@ module ActiveRecord
     class AttributeMethodCache
       def initialize
         @module = Module.new
-        @method_cache = ThreadSafe::Cache.new
+        @method_cache = Concurrent::Map.new
       end
 
       def [](name)
         @method_cache.compute_if_absent(name) do
-          safe_name = name.unpack('h*').first
+          safe_name = name.unpack('h*'.freeze).first
           temp_method = "__temp__#{safe_name}"
           ActiveRecord::AttributeMethods::AttrNames.set_name_cache safe_name, name
           @module.module_eval method_body(temp_method, safe_name), __FILE__, __LINE__
@@ -83,7 +83,7 @@ module ActiveRecord
         generated_attribute_methods.synchronize do
           return false if @attribute_methods_generated
           superclass.define_attribute_methods unless self == base_class
-          super(column_names)
+          super(attribute_names)
           @attribute_methods_generated = true
         end
         true
@@ -96,7 +96,7 @@ module ActiveRecord
         end
       end
 
-      # Raises a <tt>ActiveRecord::DangerousAttributeError</tt> exception when an
+      # Raises an ActiveRecord::DangerousAttributeError exception when an
       # \Active \Record method is defined in the model, otherwise +false+.
       #
       #   class Person < ActiveRecord::Base
@@ -106,7 +106,7 @@ module ActiveRecord
       #   end
       #
       #   Person.instance_method_already_implemented?(:save)
-      #   # => ActiveRecord::DangerousAttributeError: save is defined by ActiveRecord
+      #   # => ActiveRecord::DangerousAttributeError: save is defined by Active Record. Check to make sure that you don't have an attribute or method with the same name.
       #
       #   Person.instance_method_already_implemented?(:name)
       #   # => false
@@ -185,7 +185,7 @@ module ActiveRecord
       #   # => ["id", "created_at", "updated_at", "name", "age"]
       def attribute_names
         @attribute_names ||= if !abstract_class? && table_exists?
-            column_names
+            attribute_types.keys
           else
             []
           end
@@ -230,7 +230,15 @@ module ActiveRecord
     #   person.respond_to(:nothing) # => false
     def respond_to?(name, include_private = false)
       return false unless super
-      name = name.to_s
+
+      case name
+      when :to_partial_path
+        name = "to_partial_path".freeze
+      when :to_model
+        name = "to_model".freeze
+      else
+        name = name.to_s
+      end
 
       # If the result is true then check for the select case.
       # For queries selecting a subset of columns, return false for unselected columns.
@@ -338,7 +346,7 @@ module ActiveRecord
     #
     # Note: +:id+ is always present.
     #
-    # Alias for the <tt>read_attribute</tt> method.
+    # Alias for the #read_attribute method.
     #
     #   class Person < ActiveRecord::Base
     #     belongs_to :organization
@@ -356,7 +364,7 @@ module ActiveRecord
     end
 
     # Updates the attribute identified by <tt>attr_name</tt> with the specified +value+.
-    # (Alias for the protected <tt>write_attribute</tt> method).
+    # (Alias for the protected #write_attribute method).
     #
     #   class Person < ActiveRecord::Base
     #   end
@@ -369,6 +377,39 @@ module ActiveRecord
       write_attribute(attr_name, value)
     end
 
+    # Returns the name of all database fields which have been read from this
+    # model. This can be useful in development mode to determine which fields
+    # need to be selected. For performance critical pages, selecting only the
+    # required fields can be an easy performance win (assuming you aren't using
+    # all of the fields on the model).
+    #
+    # For example:
+    #
+    #   class PostsController < ActionController::Base
+    #     after_action :print_accessed_fields, only: :index
+    #
+    #     def index
+    #       @posts = Post.all
+    #     end
+    #
+    #     private
+    #
+    #     def print_accessed_fields
+    #       p @posts.first.accessed_fields
+    #     end
+    #   end
+    #
+    # Which allows you to quickly change your code to:
+    #
+    #   class PostsController < ActionController::Base
+    #     def index
+    #       @posts = Post.select(:id, :title, :author_id, :updated_at)
+    #     end
+    #   end
+    def accessed_fields
+      @attributes.accessed
+    end
+
     protected
 
     def clone_attribute_value(reader_method, attribute_name) # :nodoc:
diff --git a/activerecord/lib/active_record/attribute_methods/before_type_cast.rb b/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
index 56c1898551..1db6776688 100644
--- a/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
+++ b/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
@@ -2,7 +2,7 @@ module ActiveRecord
   module AttributeMethods
     # = Active Record Attribute Methods Before Type Cast
     #
-    # <tt>ActiveRecord::AttributeMethods::BeforeTypeCast</tt> provides a way to
+    # ActiveRecord::AttributeMethods::BeforeTypeCast provides a way to
     # read the value of the attributes before typecasting and deserialization.
     #
     #   class Task < ActiveRecord::Base
diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
index ce7f575150..0bcfa5f00d 100644
--- a/activerecord/lib/active_record/attribute_methods/dirty.rb
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -1,4 +1,5 @@
 require 'active_support/core_ext/module/attribute_accessors'
+require 'active_record/attribute_mutation_tracker'
 
 module ActiveRecord
   module AttributeMethods
@@ -34,23 +35,43 @@ module ActiveRecord
       # <tt>reload</tt> the record and clears changed attributes.
       def reload(*)
         super.tap do
-          clear_changes_information
+          @mutation_tracker = nil
+          @previous_mutation_tracker = nil
+          @changed_attributes = HashWithIndifferentAccess.new
         end
       end
 
       def initialize_dup(other) # :nodoc:
         super
-        calculate_changes_from_defaults
+        @attributes = self.class._default_attributes.map do |attr|
+          attr.with_value_from_user(@attributes.fetch_value(attr.name))
+        end
+        @mutation_tracker = nil
       end
 
       def changes_applied
-        super
-        store_original_raw_attributes
+        @previous_mutation_tracker = mutation_tracker
+        @changed_attributes = HashWithIndifferentAccess.new
+        store_original_attributes
       end
 
       def clear_changes_information
+        @previous_mutation_tracker = nil
+        @changed_attributes = HashWithIndifferentAccess.new
+        store_original_attributes
+      end
+
+      def raw_write_attribute(attr_name, *)
+        result = super
+        clear_attribute_change(attr_name)
+        result
+      end
+
+      def clear_attribute_changes(attr_names)
         super
-        original_raw_attributes.clear
+        attr_names.each do |attr_name|
+          clear_attribute_change(attr_name)
+        end
       end
 
       def changed_attributes
@@ -59,7 +80,7 @@ module ActiveRecord
         if defined?(@cached_changed_attributes)
           @cached_changed_attributes
         else
-          super.reverse_merge(attributes_changed_in_place).freeze
+          super.reverse_merge(mutation_tracker.changed_values).freeze
         end
       end
 
@@ -69,58 +90,29 @@ module ActiveRecord
         end
       end
 
+      def previous_changes
+        previous_mutation_tracker.changes
+      end
+
       def attribute_changed_in_place?(attr_name)
-        old_value = original_raw_attribute(attr_name)
-        @attributes[attr_name].changed_in_place_from?(old_value)
+        mutation_tracker.changed_in_place?(attr_name)
       end
 
       private
 
-      def changes_include?(attr_name)
-        super || attribute_changed_in_place?(attr_name)
-      end
-
-      def calculate_changes_from_defaults
-        @changed_attributes = nil
-        self.class.column_defaults.each do |attr, orig_value|
-          set_attribute_was(attr, orig_value) if _field_changed?(attr, orig_value)
+      def mutation_tracker
+        unless defined?(@mutation_tracker)
+          @mutation_tracker = nil
         end
+        @mutation_tracker ||= AttributeMutationTracker.new(@attributes)
       end
 
-      # Wrap write_attribute to remember original attribute value.
-      def write_attribute(attr, value)
-        attr = attr.to_s
-
-        old_value = old_attribute_value(attr)
-
-        result = super
-        store_original_raw_attribute(attr)
-        save_changed_attribute(attr, old_value)
-        result
-      end
-
-      def raw_write_attribute(attr, value)
-        attr = attr.to_s
-
-        result = super
-        original_raw_attributes[attr] = value
-        result
-      end
-
-      def save_changed_attribute(attr, old_value)
-        if attribute_changed?(attr)
-          clear_attribute_changes(attr) unless _field_changed?(attr, old_value)
-        else
-          set_attribute_was(attr, old_value) if _field_changed?(attr, old_value)
-        end
+      def changes_include?(attr_name)
+        super || mutation_tracker.changed?(attr_name)
       end
 
-      def old_attribute_value(attr)
-        if attribute_changed?(attr)
-          changed_attributes[attr]
-        else
-          clone_attribute_value(:_read_attribute, attr)
-        end
+      def clear_attribute_change(attr_name)
+        mutation_tracker.forget_change(attr_name)
       end
 
       def _update_record(*)
@@ -131,54 +123,28 @@ module ActiveRecord
         partial_writes? ? super(keys_for_partial_write) : super
       end
 
-      # Serialized attributes should always be written in case they've been
-      # changed in place.
       def keys_for_partial_write
-        changed & persistable_attribute_names
-      end
-
-      def _field_changed?(attr, old_value)
-        @attributes[attr].changed_from?(old_value)
+        changed & self.class.column_names
       end
 
-      def attributes_changed_in_place
-        changed_in_place.each_with_object({}) do |attr_name, h|
-          orig = @attributes[attr_name].original_value
-          h[attr_name] = orig
-        end
+      def store_original_attributes
+        @attributes = @attributes.map(&:forgetting_assignment)
+        @mutation_tracker = nil
       end
 
-      def changed_in_place
-        self.class.attribute_names.select do |attr_name|
-          attribute_changed_in_place?(attr_name)
-        end
-      end
-
-      def original_raw_attribute(attr_name)
-        original_raw_attributes.fetch(attr_name) do
-          read_attribute_before_type_cast(attr_name)
-        end
-      end
-
-      def original_raw_attributes
-        @original_raw_attributes ||= {}
-      end
-
-      def store_original_raw_attribute(attr_name)
-        original_raw_attributes[attr_name] = @attributes[attr_name].value_for_database
-      end
-
-      def store_original_raw_attributes
-        attribute_names.each do |attr|
-          store_original_raw_attribute(attr)
-        end
+      def previous_mutation_tracker
+        @previous_mutation_tracker ||= NullMutationTracker.instance
       end
 
       def cache_changed_attributes
         @cached_changed_attributes = changed_attributes
         yield
       ensure
-        remove_instance_variable(:@cached_changed_attributes)
+        clear_changed_attributes_cache
+      end
+
+      def clear_changed_attributes_cache
+        remove_instance_variable(:@cached_changed_attributes) if defined?(@cached_changed_attributes)
       end
     end
   end
diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index c28374e4ab..0d5cb8b37c 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -5,7 +5,7 @@ module ActiveRecord
     module PrimaryKey
       extend ActiveSupport::Concern
 
-      # Returns this record's primary key value wrapped in an Array if one is
+      # Returns this record's primary key value wrapped in an array if one is
       # available.
       def to_key
         sync_with_transaction_state
@@ -108,7 +108,7 @@ module ActiveRecord
         #     self.primary_key = 'sysid'
         #   end
         #
-        # You can also define the +primary_key+ method yourself:
+        # You can also define the #primary_key method yourself:
         #
         #   class Project < ActiveRecord::Base
         #     def self.primary_key
diff --git a/activerecord/lib/active_record/attribute_methods/query.rb b/activerecord/lib/active_record/attribute_methods/query.rb
index dc689f399a..10498f4322 100644
--- a/activerecord/lib/active_record/attribute_methods/query.rb
+++ b/activerecord/lib/active_record/attribute_methods/query.rb
@@ -19,10 +19,10 @@ module ActiveRecord
             if Numeric === value || value !~ /[^0-9]/
               !value.to_i.zero?
             else
-              return false if ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES.include?(value)
+              return false if ActiveModel::Type::Boolean::FALSE_VALUES.include?(value)
               !value.blank?
             end
-          elsif column.number?
+          elsif value.respond_to?(:zero?)
             !value.zero?
           else
             !value.blank?
diff --git a/activerecord/lib/active_record/attribute_methods/read.rb b/activerecord/lib/active_record/attribute_methods/read.rb
index 24e30b6608..5197e21fa4 100644
--- a/activerecord/lib/active_record/attribute_methods/read.rb
+++ b/activerecord/lib/active_record/attribute_methods/read.rb
@@ -37,7 +37,7 @@ module ActiveRecord
         protected
 
         def define_method_attribute(name)
-          safe_name = name.unpack('h*').first
+          safe_name = name.unpack('h*'.freeze).first
           temp_method = "__temp__#{safe_name}"
 
           ActiveRecord::AttributeMethods::AttrNames.set_name_cache safe_name, name
@@ -56,22 +56,29 @@ module ActiveRecord
         end
       end
 
-      ID = 'id'.freeze
-
       # Returns the value of the attribute identified by <tt>attr_name</tt> after
       # it has been typecast (for example, "2004-12-12" in a date column is cast
       # to a date object, like Date.new(2004, 12, 12)).
       def read_attribute(attr_name, &block)
         name = attr_name.to_s
-        name = self.class.primary_key if name == ID
+        name = self.class.primary_key if name == 'id'.freeze
         _read_attribute(name, &block)
       end
 
       # This method exists to avoid the expensive primary_key check internally, without
       # breaking compatibility with the read_attribute API
-      def _read_attribute(attr_name) # :nodoc:
-        @attributes.fetch_value(attr_name.to_s) { |n| yield n if block_given? }
+      if defined?(JRUBY_VERSION)
+        # This form is significantly faster on JRuby, and this is one of our biggest hotspots.
+        # https://github.com/jruby/jruby/pull/2562
+        def _read_attribute(attr_name, &block) # :nodoc
+          @attributes.fetch_value(attr_name.to_s, &block)
+        end
+      else
+        def _read_attribute(attr_name) # :nodoc:
+          @attributes.fetch_value(attr_name.to_s) { |n| yield n if block_given? }
+        end
       end
+
       alias :attribute :_read_attribute
       private :attribute
 
diff --git a/activerecord/lib/active_record/attribute_methods/serialization.rb b/activerecord/lib/active_record/attribute_methods/serialization.rb
index d0d8a968c5..65978aea2a 100644
--- a/activerecord/lib/active_record/attribute_methods/serialization.rb
+++ b/activerecord/lib/active_record/attribute_methods/serialization.rb
@@ -9,7 +9,19 @@ module ActiveRecord
         # attribute using this method and it will be handled automatically. The
         # serialization is done through YAML. If +class_name+ is specified, the
         # serialized object must be of that class on assignment and retrieval.
-        # Otherwise <tt>SerializationTypeMismatch</tt> will be raised.
+        # Otherwise SerializationTypeMismatch will be raised.
+        #
+        # Empty objects as <tt>{}</tt>, in the case of +Hash+, or <tt>[]</tt>, in the case of
+        # +Array+, will always be persisted as null.
+        #
+        # Keep in mind that database adapters handle certain serialization tasks
+        # for you. For instance: +json+ and +jsonb+ types in PostgreSQL will be
+        # converted between JSON object/array syntax and Ruby +Hash+ or +Array+
+        # objects transparently. There is no need to use #serialize in this
+        # case.
+        #
+        # For more complex cases, such as conversion to or from your application
+        # domain objects, consider using the ActiveRecord::Attributes API.
         #
         # ==== Parameters
         #
diff --git a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
index 98671178cb..9e693b6aee 100644
--- a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
+++ b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
@@ -2,24 +2,26 @@ module ActiveRecord
   module AttributeMethods
     module TimeZoneConversion
       class TimeZoneConverter < DelegateClass(Type::Value) # :nodoc:
-        include Type::Decorator
-
-        def type_cast_from_database(value)
+        def deserialize(value)
           convert_time_to_time_zone(super)
         end
 
-        def type_cast_from_user(value)
+        def cast(value)
           if value.is_a?(Array)
-            value.map { |v| type_cast_from_user(v) }
+            value.map { |v| cast(v) }
+          elsif value.is_a?(Hash)
+            set_time_zone_without_conversion(super)
           elsif value.respond_to?(:in_time_zone)
             begin
-              user_input_in_time_zone(value) || super
+              super(user_input_in_time_zone(value)) || super
             rescue ArgumentError
               nil
             end
           end
         end
 
+        private
+
         def convert_time_to_time_zone(value)
           if value.is_a?(Array)
             value.map { |v| convert_time_to_time_zone(v) }
@@ -29,6 +31,10 @@ module ActiveRecord
             value
           end
         end
+
+        def set_time_zone_without_conversion(value)
+          ::Time.zone.local_to_utc(value).in_time_zone
+        end
       end
 
       extend ActiveSupport::Concern
@@ -73,7 +79,7 @@ module ActiveRecord
             time_zone_aware_types.include?(:not_explicitly_configured)
             ActiveSupport::Deprecation.warn(<<-MESSAGE)
               Time columns will become time zone aware in Rails 5.1. This
-              still cause `String`s to be parsed as if they were in `Time.zone`,
+              still causes `String`s to be parsed as if they were in `Time.zone`,
               and `Time`s to be converted to `Time.zone`.
 
               To keep the old behavior, you must add the following to your initializer:
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index ab017c7b54..bbf2a51a0e 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -24,7 +24,7 @@ module ActiveRecord
         protected
 
         def define_method_attribute=(name)
-          safe_name = name.unpack('h*').first
+          safe_name = name.unpack('h*'.freeze).first
           ActiveRecord::AttributeMethods::AttrNames.set_name_cache safe_name, name
 
           generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1
@@ -45,7 +45,7 @@ module ActiveRecord
         write_attribute_with_type_cast(attr_name, value, true)
       end
 
-      def raw_write_attribute(attr_name, value)
+      def raw_write_attribute(attr_name, value) # :nodoc:
         write_attribute_with_type_cast(attr_name, value, false)
       end
 
diff --git a/activerecord/lib/active_record/attribute_mutation_tracker.rb b/activerecord/lib/active_record/attribute_mutation_tracker.rb
new file mode 100644
index 0000000000..0133b4d0be
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_mutation_tracker.rb
@@ -0,0 +1,70 @@
+module ActiveRecord
+  class AttributeMutationTracker # :nodoc:
+    def initialize(attributes)
+      @attributes = attributes
+    end
+
+    def changed_values
+      attr_names.each_with_object({}.with_indifferent_access) do |attr_name, result|
+        if changed?(attr_name)
+          result[attr_name] = attributes[attr_name].original_value
+        end
+      end
+    end
+
+    def changes
+      attr_names.each_with_object({}.with_indifferent_access) do |attr_name, result|
+        if changed?(attr_name)
+          result[attr_name] = [attributes[attr_name].original_value, attributes.fetch_value(attr_name)]
+        end
+      end
+    end
+
+    def changed?(attr_name)
+      attr_name = attr_name.to_s
+      attributes[attr_name].changed?
+    end
+
+    def changed_in_place?(attr_name)
+      attributes[attr_name].changed_in_place?
+    end
+
+    def forget_change(attr_name)
+      attr_name = attr_name.to_s
+      attributes[attr_name] = attributes[attr_name].forgetting_assignment
+    end
+
+    protected
+
+    attr_reader :attributes
+
+    private
+
+    def attr_names
+      attributes.keys
+    end
+  end
+
+  class NullMutationTracker # :nodoc:
+    include Singleton
+
+    def changed_values
+      {}
+    end
+
+    def changes
+      {}
+    end
+
+    def changed?(*)
+      false
+    end
+
+    def changed_in_place?(*)
+      false
+    end
+
+    def forget_change(*)
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_set.rb b/activerecord/lib/active_record/attribute_set.rb
index 66fcaf6945..be581ac2a9 100644
--- a/activerecord/lib/active_record/attribute_set.rb
+++ b/activerecord/lib/active_record/attribute_set.rb
@@ -10,6 +10,10 @@ module ActiveRecord
       attributes[name] || Attribute.null(name)
     end
 
+    def []=(name, value)
+      attributes[name] = value
+    end
+
     def values_before_type_cast
       attributes.transform_values(&:value_before_type_cast)
     end
@@ -24,11 +28,19 @@ module ActiveRecord
     end
 
     def keys
-      attributes.initialized_keys
+      attributes.each_key.select { |name| self[name].initialized? }
     end
 
-    def fetch_value(name)
-      self[name].value { |n| yield n if block_given? }
+    if defined?(JRUBY_VERSION)
+      # This form is significantly faster on JRuby, and this is one of our biggest hotspots.
+      # https://github.com/jruby/jruby/pull/2562
+      def fetch_value(name, &block)
+        self[name].value(&block)
+      end
+    else
+      def fetch_value(name)
+        self[name].value { |n| yield n if block_given? }
+      end
     end
 
     def write_from_database(name, value)
@@ -48,6 +60,12 @@ module ActiveRecord
       super
     end
 
+    def deep_dup
+      dup.tap do |copy|
+        copy.instance_variable_set(:@attributes, attributes.deep_dup)
+      end
+    end
+
     def initialize_dup(_)
       @attributes = attributes.dup
       super
@@ -64,6 +82,19 @@ module ActiveRecord
       end
     end
 
+    def accessed
+      attributes.select { |_, attr| attr.has_been_read? }.keys
+    end
+
+    def map(&block)
+      new_attributes = attributes.transform_values(&block)
+      AttributeSet.new(new_attributes)
+    end
+
+    def ==(other)
+      attributes == other.attributes
+    end
+
     protected
 
     attr_reader :attributes
diff --git a/activerecord/lib/active_record/attribute_set/builder.rb b/activerecord/lib/active_record/attribute_set/builder.rb
index 3a76f5262d..3bd7c7997b 100644
--- a/activerecord/lib/active_record/attribute_set/builder.rb
+++ b/activerecord/lib/active_record/attribute_set/builder.rb
@@ -1,3 +1,5 @@
+require 'active_record/attribute'
+
 module ActiveRecord
   class AttributeSet # :nodoc:
     class Builder # :nodoc:
@@ -20,7 +22,7 @@ module ActiveRecord
   end
 
   class LazyAttributeHash # :nodoc:
-    delegate :select, :transform_values, to: :materialize
+    delegate :transform_values, :each_key, to: :materialize
 
     def initialize(types, values, additional_types)
       @types = types
@@ -45,19 +47,50 @@ module ActiveRecord
       delegate_hash[key] = value
     end
 
-    def initialized_keys
-      delegate_hash.keys | values.keys
+    def deep_dup
+      dup.tap do |copy|
+        copy.instance_variable_set(:@delegate_hash, delegate_hash.transform_values(&:dup))
+      end
     end
 
     def initialize_dup(_)
-      @delegate_hash = delegate_hash.transform_values(&:dup)
+      @delegate_hash = Hash[delegate_hash]
       super
     end
 
+    def select
+      keys = types.keys | values.keys | delegate_hash.keys
+      keys.each_with_object({}) do |key, hash|
+        attribute = self[key]
+        if yield(key, attribute)
+          hash[key] = attribute
+        end
+      end
+    end
+
+    def ==(other)
+      if other.is_a?(LazyAttributeHash)
+        materialize == other.materialize
+      else
+        materialize == other
+      end
+    end
+
     protected
 
     attr_reader :types, :values, :additional_types, :delegate_hash
 
+    def materialize
+      unless @materialized
+        values.each_key { |key| self[key] }
+        types.each_key { |key| self[key] }
+        unless frozen?
+          @materialized = true
+        end
+      end
+      delegate_hash
+    end
+
     private
 
     def assign_default_value(name)
@@ -71,16 +104,5 @@ module ActiveRecord
         delegate_hash[name] = Attribute.uninitialized(name, type)
       end
     end
-
-    def materialize
-      unless @materialized
-        values.each_key { |key| self[key] }
-        types.each_key { |key| self[key] }
-        unless frozen?
-          @materialized = true
-        end
-      end
-      delegate_hash
-    end
   end
 end
diff --git a/activerecord/lib/active_record/attributes.rb b/activerecord/lib/active_record/attributes.rb
index b263a89d79..5d0405c3be 100644
--- a/activerecord/lib/active_record/attributes.rb
+++ b/activerecord/lib/active_record/attributes.rb
@@ -1,33 +1,44 @@
+require 'active_record/attribute/user_provided_default'
+
 module ActiveRecord
-  module Attributes # :nodoc:
+  # See ActiveRecord::Attributes::ClassMethods for documentation
+  module Attributes
     extend ActiveSupport::Concern
 
-    Type = ActiveRecord::Type
-
     included do
-      class_attribute :user_provided_columns, instance_accessor: false # :internal:
-      class_attribute :user_provided_defaults, instance_accessor: false # :internal:
-      self.user_provided_columns = {}
-      self.user_provided_defaults = {}
-
-      delegate :persistable_attribute_names, to: :class
+      class_attribute :attributes_to_define_after_schema_loads, instance_accessor: false # :internal:
+      self.attributes_to_define_after_schema_loads = {}
     end
 
-    module ClassMethods # :nodoc:
-      # Defines or overrides a attribute on this model. This allows customization of
-      # Active Record's type casting behavior, as well as adding support for user defined
-      # types.
+    module ClassMethods
+      # Defines an attribute with a type on this model. It will override the
+      # type of existing attributes if needed. This allows control over how
+      # values are converted to and from SQL when assigned to a model. It also
+      # changes the behavior of values passed to
+      # {ActiveRecord::Base.where}[rdoc-ref:QueryMethods#where]. This will let you use
+      # your domain objects across much of Active Record, without having to
+      # rely on implementation details or monkey patching.
       #
-      # +name+ The name of the methods to define attribute methods for, and the column which
-      # this will persist to.
+      # +name+ The name of the methods to define attribute methods for, and the
+      # column which this will persist to.
       #
-      # +cast_type+ A type object that contains information about how to type cast the value.
-      # See the examples section for more information.
+      # +cast_type+ A symbol such as +:string+ or +:integer+, or a type object
+      # to be used for this attribute. See the examples below for more
+      # information about providing custom type objects.
       #
       # ==== Options
-      # The options hash accepts the following options:
       #
-      # +default+ is the default value that the column should use on a new record.
+      # The following options are accepted:
+      #
+      # +default+ The default value to use when no value is provided. If this option
+      # is not passed, the previous default value (if any) will be used.
+      # Otherwise, the default will be +nil+.
+      #
+      # +array+ (PG only) specifies that the type should be an array (see the
+      # examples below).
+      #
+      # +range+ (PG only) specifies that the type should be a range (see the
+      # examples below).
       #
       # ==== Examples
       #
@@ -48,99 +59,201 @@ module ActiveRecord
       #   store_listing.price_in_cents # => BigDecimal.new(10.1)
       #
       #   class StoreListing < ActiveRecord::Base
-      #     attribute :price_in_cents, Type::Integer.new
+      #     attribute :price_in_cents, :integer
       #   end
       #
       #   # after
       #   store_listing.price_in_cents # => 10
       #
-      # Users may also define their own custom types, as long as they respond to the methods
-      # defined on the value type. The +type_cast+ method on your type object will be called
-      # with values both from the database, and from your controllers. See
-      # +ActiveRecord::Attributes::Type::Value+ for the expected API. It is recommended that your
-      # type objects inherit from an existing type, or the base value type.
+      # A default can also be provided.
+      #
+      #   create_table :store_listings, force: true do |t|
+      #     t.string :my_string, default: "original default"
+      #   end
+      #
+      #   StoreListing.new.my_string # => "original default"
+      #
+      #   class StoreListing < ActiveRecord::Base
+      #     attribute :my_string, :string, default: "new default"
+      #   end
+      #
+      #   StoreListing.new.my_string # => "new default"
+      #
+      #   class Product < ActiveRecord::Base
+      #     attribute :my_default_proc, :datetime, default: -> { Time.now }
+      #   end
+      #
+      #   Product.new.my_default_proc # => 2015-05-30 11:04:48 -0600
+      #   sleep 1
+      #   Product.new.my_default_proc # => 2015-05-30 11:04:49 -0600
+      #
+      # \Attributes do not need to be backed by a database column.
+      #
+      #   class MyModel < ActiveRecord::Base
+      #     attribute :my_string, :string
+      #     attribute :my_int_array, :integer, array: true
+      #     attribute :my_float_range, :float, range: true
+      #   end
+      #
+      #   model = MyModel.new(
+      #     my_string: "string",
+      #     my_int_array: ["1", "2", "3"],
+      #     my_float_range: "[1,3.5]",
+      #   )
+      #   model.attributes
+      #   # =>
+      #     {
+      #       my_string: "string",
+      #       my_int_array: [1, 2, 3],
+      #       my_float_range: 1.0..3.5
+      #     }
+      #
+      # ==== Creating Custom Types
+      #
+      # Users may also define their own custom types, as long as they respond
+      # to the methods defined on the value type. The method +deserialize+ or
+      # +cast+ will be called on your type object, with raw input from the
+      # database or from your controllers. See ActiveRecord::Type::Value for the
+      # expected API. It is recommended that your type objects inherit from an
+      # existing type, or from ActiveRecord::Type::Value
       #
       #   class MoneyType < ActiveRecord::Type::Integer
-      #     def type_cast(value)
-      #       if value.include?('$')
+      #     def cast(value)
+      #       if !value.kind_of(Numeric) && value.include?('$')
       #         price_in_dollars = value.gsub(/\$/, '').to_f
-      #         price_in_dollars * 100
+      #         super(price_in_dollars * 100)
       #       else
-      #         value.to_i
+      #         super
       #       end
       #     end
       #   end
       #
+      #   # config/initializers/types.rb
+      #   ActiveRecord::Type.register(:money, MoneyType)
+      #
+      #   # /app/models/store_listing.rb
       #   class StoreListing < ActiveRecord::Base
-      #     attribute :price_in_cents, MoneyType.new
+      #     attribute :price_in_cents, :money
       #   end
       #
       #   store_listing = StoreListing.new(price_in_cents: '$10.00')
       #   store_listing.price_in_cents # => 1000
-      def attribute(name, cast_type, options = {})
+      #
+      # For more details on creating custom types, see the documentation for
+      # ActiveRecord::Type::Value. For more details on registering your types
+      # to be referenced by a symbol, see ActiveRecord::Type.register. You can
+      # also pass a type object directly, in place of a symbol.
+      #
+      # ==== \Querying
+      #
+      # When {ActiveRecord::Base.where}[rdoc-ref:QueryMethods#where] is called, it will
+      # use the type defined by the model class to convert the value to SQL,
+      # calling +serialize+ on your type object. For example:
+      #
+      #   class Money < Struct.new(:amount, :currency)
+      #   end
+      #
+      #   class MoneyType < Type::Value
+      #     def initialize(currency_converter)
+      #       @currency_converter = currency_converter
+      #     end
+      #
+      #     # value will be the result of +deserialize+ or
+      #     # +cast+. Assumed to be an instance of +Money+ in
+      #     # this case.
+      #     def serialize(value)
+      #       value_in_bitcoins = @currency_converter.convert_to_bitcoins(value)
+      #       value_in_bitcoins.amount
+      #     end
+      #   end
+      #
+      #   ActiveRecord::Type.register(:money, MoneyType)
+      #
+      #   class Product < ActiveRecord::Base
+      #     currency_converter = ConversionRatesFromTheInternet.new
+      #     attribute :price_in_bitcoins, :money, currency_converter
+      #   end
+      #
+      #   Product.where(price_in_bitcoins: Money.new(5, "USD"))
+      #   # => SELECT * FROM products WHERE price_in_bitcoins = 0.02230
+      #
+      #   Product.where(price_in_bitcoins: Money.new(5, "GBP"))
+      #   # => SELECT * FROM products WHERE price_in_bitcoins = 0.03412
+      #
+      # ==== Dirty Tracking
+      #
+      # The type of an attribute is given the opportunity to change how dirty
+      # tracking is performed. The methods +changed?+ and +changed_in_place?+
+      # will be called from ActiveModel::Dirty. See the documentation for those
+      # methods in ActiveRecord::Type::Value for more details.
+      def attribute(name, cast_type, **options)
         name = name.to_s
-        clear_caches_calculated_from_columns
-        # Assign a new hash to ensure that subclasses do not share a hash
-        self.user_provided_columns = user_provided_columns.merge(name => cast_type)
-
-        if options.key?(:default)
-          self.user_provided_defaults = user_provided_defaults.merge(name => options[:default])
-        end
-      end
-
-      # Returns an array of column objects for the table associated with this class.
-      def columns
-        @columns ||= add_user_provided_columns(connection.schema_cache.columns(table_name))
-      end
+        reload_schema_from_cache
 
-      # Returns a hash of column objects for the table associated with this class.
-      def columns_hash
-        @columns_hash ||= Hash[columns.map { |c| [c.name, c] }]
+        self.attributes_to_define_after_schema_loads =
+          attributes_to_define_after_schema_loads.merge(
+            name => [cast_type, options]
+          )
       end
 
-      def persistable_attribute_names # :nodoc:
-        @persistable_attribute_names ||= connection.schema_cache.columns_hash(table_name).keys
+      # This is the low level API which sits beneath +attribute+. It only
+      # accepts type objects, and will do its work immediately instead of
+      # waiting for the schema to load. Automatic schema detection and
+      # ClassMethods#attribute both call this under the hood. While this method
+      # is provided so it can be used by plugin authors, application code
+      # should probably use ClassMethods#attribute.
+      #
+      # +name+ The name of the attribute being defined. Expected to be a +String+.
+      #
+      # +cast_type+ The type object to use for this attribute.
+      #
+      # +default+ The default value to use when no value is provided. If this option
+      # is not passed, the previous default value (if any) will be used.
+      # Otherwise, the default will be +nil+. A proc can also be passed, and
+      # will be called once each time a new value is needed.
+      #
+      # +user_provided_default+ Whether the default value should be cast using
+      # +cast+ or +deserialize+.
+      def define_attribute(
+        name,
+        cast_type,
+        default: NO_DEFAULT_PROVIDED,
+        user_provided_default: true
+      )
+        attribute_types[name] = cast_type
+        define_default_attribute(name, default, cast_type, from_user: user_provided_default)
       end
 
-      def reset_column_information # :nodoc:
+      def load_schema! # :nodoc:
         super
-        clear_caches_calculated_from_columns
-      end
-
-      private
-
-      def add_user_provided_columns(schema_columns)
-        existing_columns = schema_columns.map do |column|
-          new_type = user_provided_columns[column.name]
-          if new_type
-            column.with_type(new_type)
-          else
-            column
+        attributes_to_define_after_schema_loads.each do |name, (type, options)|
+          if type.is_a?(Symbol)
+            type = ActiveRecord::Type.lookup(type, **options.except(:default))
           end
-        end
 
-        existing_column_names = existing_columns.map(&:name)
-        new_columns = user_provided_columns.except(*existing_column_names).map do |(name, type)|
-          connection.new_column(name, nil, type)
+          define_attribute(name, type, **options.slice(:default))
         end
-
-        existing_columns + new_columns
       end
 
-      def clear_caches_calculated_from_columns
-        @arel_table = nil
-        @attributes_builder = nil
-        @column_names = nil
-        @column_types = nil
-        @columns = nil
-        @columns_hash = nil
-        @content_columns = nil
-        @default_attributes = nil
-        @persistable_attribute_names = nil
-      end
+      private
+
+      NO_DEFAULT_PROVIDED = Object.new # :nodoc:
+      private_constant :NO_DEFAULT_PROVIDED
 
-      def raw_default_values
-        super.merge(user_provided_defaults)
+      def define_default_attribute(name, value, type, from_user:)
+        if value == NO_DEFAULT_PROVIDED
+          default_attribute = _default_attributes[name].with_type(type)
+        elsif from_user
+          default_attribute = Attribute::UserProvidedDefault.new(
+            name,
+            value,
+            type,
+            _default_attributes[name],
+          )
+        else
+          default_attribute = Attribute.from_database(name, value, type)
+        end
+        _default_attributes[name] = default_attribute
       end
     end
   end
diff --git a/activerecord/lib/active_record/autosave_association.rb b/activerecord/lib/active_record/autosave_association.rb
index fcaaffb852..fc12c3f45a 100644
--- a/activerecord/lib/active_record/autosave_association.rb
+++ b/activerecord/lib/active_record/autosave_association.rb
@@ -1,10 +1,10 @@
 module ActiveRecord
   # = Active Record Autosave Association
   #
-  # +AutosaveAssociation+ is a module that takes care of automatically saving
+  # AutosaveAssociation is a module that takes care of automatically saving
   # associated records when their parent is saved. In addition to saving, it
   # also destroys any associated records that were marked for destruction.
-  # (See +mark_for_destruction+ and <tt>marked_for_destruction?</tt>).
+  # (See #mark_for_destruction and #marked_for_destruction?).
   #
   # Saving of the parent, its associations, and the destruction of marked
   # associations, all happen inside a transaction. This should never leave the
@@ -125,7 +125,6 @@ module ActiveRecord
   # Now it _is_ removed from the database:
   #
   #   Comment.find_by(id: id).nil? # => true
-
   module AutosaveAssociation
     extend ActiveSupport::Concern
 
@@ -141,9 +140,11 @@ module ActiveRecord
 
     included do
       Associations::Builder::Association.extensions << AssociationBuilderExtension
+      mattr_accessor :index_nested_attribute_errors, instance_writer: false
+      self.index_nested_attribute_errors = false
     end
 
-    module ClassMethods
+    module ClassMethods # :nodoc:
       private
 
         def define_non_cyclic_method(name, &block)
@@ -177,10 +178,8 @@ module ActiveRecord
         # before actually defining them.
         def add_autosave_association_callbacks(reflection)
           save_method = :"autosave_associated_records_for_#{reflection.name}"
-          validation_method = :"validate_associated_records_for_#{reflection.name}"
-          collection = reflection.collection?
 
-          if collection
+          if reflection.collection?
             before_save :before_save_collection_association
 
             define_non_cyclic_method(save_method) { save_collection_association(reflection) }
@@ -204,8 +203,18 @@ module ActiveRecord
             before_save save_method
           end
 
+          define_autosave_validation_callbacks(reflection)
+        end
+
+        def define_autosave_validation_callbacks(reflection)
+          validation_method = :"validate_associated_records_for_#{reflection.name}"
           if reflection.validate? && !method_defined?(validation_method)
-            method = (collection ? :validate_collection_association : :validate_single_association)
+            if reflection.collection?
+              method = :validate_collection_association
+            else
+              method = :validate_single_association
+            end
+
             define_non_cyclic_method(validation_method) do
               send(method, reflection)
               # TODO: remove the following line as soon as the return value of
@@ -214,6 +223,7 @@ module ActiveRecord
               true
             end
             validate validation_method
+            after_validation :_ensure_no_duplicate_errors
           end
         end
     end
@@ -225,7 +235,7 @@ module ActiveRecord
       super
     end
 
-    # Marks this record to be destroyed as part of the parents save transaction.
+    # Marks this record to be destroyed as part of the parent's save transaction.
     # This does _not_ actually destroy the record instantly, rather child record will be destroyed
     # when <tt>parent.save</tt> is called.
     #
@@ -234,7 +244,7 @@ module ActiveRecord
       @marked_for_destruction = true
     end
 
-    # Returns whether or not this record will be destroyed as part of the parents save transaction.
+    # Returns whether or not this record will be destroyed as part of the parent's save transaction.
     #
     # Only useful if the <tt>:autosave</tt> option on the parent is enabled for this associated model.
     def marked_for_destruction?
@@ -307,7 +317,7 @@ module ActiveRecord
       def validate_collection_association(reflection)
         if association = association_instance_get(reflection.name)
           if records = associated_records_to_validate_or_save(association, new_record?, reflection.options[:autosave])
-            records.each { |record| association_valid?(reflection, record) }
+            records.each_with_index { |record, index| association_valid?(reflection, record, index) }
           end
         end
       end
@@ -315,14 +325,18 @@ module ActiveRecord
       # Returns whether or not the association is valid and applies any errors to
       # the parent, <tt>self</tt>, if it wasn't. Skips any <tt>:autosave</tt>
       # enabled records if they're marked_for_destruction? or destroyed.
-      def association_valid?(reflection, record)
-        return true if record.destroyed? || record.marked_for_destruction?
+      def association_valid?(reflection, record, index=nil)
+        return true if record.destroyed? || (reflection.options[:autosave] && record.marked_for_destruction?)
 
         validation_context = self.validation_context unless [:create, :update].include?(self.validation_context)
         unless valid = record.valid?(validation_context)
           if reflection.options[:autosave]
             record.errors.each do |attribute, message|
-              attribute = "#{reflection.name}.#{attribute}"
+              if index.nil? || (!reflection.options[:index_errors] && !ActiveRecord::Base.index_nested_attribute_errors)
+                attribute = "#{reflection.name}.#{attribute}"
+              else
+                attribute = "#{reflection.name}[#{index}].#{attribute}"
+              end
               errors[attribute] << message
               errors[attribute].uniq!
             end
@@ -344,7 +358,7 @@ module ActiveRecord
       # <tt>:autosave</tt> is enabled on the association.
       #
       # In addition, it destroys all children that were marked for destruction
-      # with mark_for_destruction.
+      # with #mark_for_destruction.
       #
       # This all happens inside a transaction, _if_ the Transactions module is included into
       # ActiveRecord::Base after the AutosaveAssociation module, which it does by default.
@@ -387,7 +401,7 @@ module ActiveRecord
       # on the association.
       #
       # In addition, it will destroy the association if it was marked for
-      # destruction with mark_for_destruction.
+      # destruction with #mark_for_destruction.
       #
       # This all happens inside a transaction, _if_ the Transactions module is included into
       # ActiveRecord::Base after the AutosaveAssociation module, which it does by default.
@@ -448,5 +462,11 @@ module ActiveRecord
           end
         end
       end
+
+      def _ensure_no_duplicate_errors
+        errors.messages.each_key do |attribute|
+          errors[attribute].uniq!
+        end
+      end
   end
 end
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 100d3780f6..9782e58299 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -1,11 +1,9 @@
 require 'yaml'
-require 'set'
 require 'active_support/benchmarkable'
 require 'active_support/dependencies'
 require 'active_support/descendants_tracker'
 require 'active_support/time'
 require 'active_support/core_ext/module/attribute_accessors'
-require 'active_support/core_ext/class/delegating_attributes'
 require 'active_support/core_ext/array/extract_options'
 require 'active_support/core_ext/hash/deep_merge'
 require 'active_support/core_ext/hash/slice'
@@ -120,23 +118,22 @@ module ActiveRecord #:nodoc:
   # All column values are automatically available through basic accessors on the Active Record
   # object, but sometimes you want to specialize this behavior. This can be done by overwriting
   # the default accessors (using the same name as the attribute) and calling
-  # <tt>read_attribute(attr_name)</tt> and <tt>write_attribute(attr_name, value)</tt> to actually
-  # change things.
+  # +super+ to actually change things.
   #
   #   class Song < ActiveRecord::Base
   #     # Uses an integer of seconds to hold the length of the song
   #
   #     def length=(minutes)
-  #       write_attribute(:length, minutes.to_i * 60)
+  #       super(minutes.to_i * 60)
   #     end
   #
   #     def length
-  #       read_attribute(:length) / 60
+  #       super / 60
   #     end
   #   end
   #
   # You can alternatively use <tt>self[:attribute]=(value)</tt> and <tt>self[:attribute]</tt>
-  # instead of <tt>write_attribute(:attribute, value)</tt> and <tt>read_attribute(:attribute)</tt>.
+  # or <tt>write_attribute(:attribute, value)</tt> and <tt>read_attribute(:attribute)</tt>.
   #
   # == Attribute query methods
   #
@@ -173,7 +170,7 @@ module ActiveRecord #:nodoc:
   # <tt>Person.find_by_user_name(user_name)</tt>.
   #
   # It's possible to add an exclamation point (!) on the end of the dynamic finders to get them to raise an
-  # <tt>ActiveRecord::RecordNotFound</tt> error if they do not return any records,
+  # ActiveRecord::RecordNotFound error if they do not return any records,
   # like <tt>Person.find_by_last_name!</tt>.
   #
   # It's also possible to use multiple attributes in the same find by separating them with "_and_".
@@ -188,7 +185,8 @@ module ActiveRecord #:nodoc:
   # == Saving arrays, hashes, and other non-mappable objects in text columns
   #
   # Active Record can serialize any object in text columns using YAML. To do so, you must
-  # specify this with a call to the class method +serialize+.
+  # specify this with a call to the class method
+  # {serialize}[rdoc-ref:AttributeMethods::Serialization::ClassMethods#serialize].
   # This makes it possible to store arrays, hashes, and other non-mappable objects without doing
   # any additional work.
   #
@@ -228,39 +226,47 @@ module ActiveRecord #:nodoc:
   #
   # == Connection to multiple databases in different models
   #
-  # Connections are usually created through ActiveRecord::Base.establish_connection and retrieved
+  # Connections are usually created through
+  # {ActiveRecord::Base.establish_connection}[rdoc-ref:ConnectionHandling#establish_connection] and retrieved
   # by ActiveRecord::Base.connection. All classes inheriting from ActiveRecord::Base will use this
   # connection. But you can also set a class-specific connection. For example, if Course is an
   # ActiveRecord::Base, but resides in a different database, you can just say <tt>Course.establish_connection</tt>
   # and Course and all of its subclasses will use this connection instead.
   #
   # This feature is implemented by keeping a connection pool in ActiveRecord::Base that is
-  # a Hash indexed by the class. If a connection is requested, the retrieve_connection method
+  # a hash indexed by the class. If a connection is requested, the
+  # {ActiveRecord::Base.retrieve_connection}[rdoc-ref:ConnectionHandling#retrieve_connection] method
   # will go up the class-hierarchy until a connection is found in the connection pool.
   #
   # == Exceptions
   #
   # * ActiveRecordError - Generic error class and superclass of all other errors raised by Active Record.
-  # * AdapterNotSpecified - The configuration hash used in <tt>establish_connection</tt> didn't include an
-  #   <tt>:adapter</tt> key.
-  # * AdapterNotFound - The <tt>:adapter</tt> key used in <tt>establish_connection</tt> specified a
-  #   non-existent adapter
+  # * AdapterNotSpecified - The configuration hash used in
+  #   {ActiveRecord::Base.establish_connection}[rdoc-ref:ConnectionHandling#establish_connection]
+  #   didn't include an <tt>:adapter</tt> key.
+  # * AdapterNotFound - The <tt>:adapter</tt> key used in
+  #   {ActiveRecord::Base.establish_connection}[rdoc-ref:ConnectionHandling#establish_connection]
+  #   specified a non-existent adapter
   #   (or a bad spelling of an existing one).
   # * AssociationTypeMismatch - The object assigned to the association wasn't of the type
   #   specified in the association definition.
   # * AttributeAssignmentError - An error occurred while doing a mass assignment through the
-  #   <tt>attributes=</tt> method.
+  #   {ActiveRecord::Base#attributes=}[rdoc-ref:AttributeAssignment#attributes=] method.
   #   You can inspect the +attribute+ property of the exception object to determine which attribute
   #   triggered the error.
-  # * ConnectionNotEstablished - No connection has been established. Use <tt>establish_connection</tt>
-  #   before querying.
+  # * ConnectionNotEstablished - No connection has been established.
+  #   Use {ActiveRecord::Base.establish_connection}[rdoc-ref:ConnectionHandling#establish_connection] before querying.
   # * MultiparameterAssignmentErrors - Collection of errors that occurred during a mass assignment using the
-  #   <tt>attributes=</tt> method. The +errors+ property of this exception contains an array of
+  #   {ActiveRecord::Base#attributes=}[rdoc-ref:AttributeAssignment#attributes=] method.
+  #   The +errors+ property of this exception contains an array of
   #   AttributeAssignmentError
   #   objects that should be inspected to determine which attributes triggered the errors.
-  # * RecordInvalid - raised by save! and create! when the record is invalid.
-  # * RecordNotFound - No record responded to the +find+ method. Either the row with the given ID doesn't exist
-  #   or the row didn't meet the additional restrictions. Some +find+ calls do not raise this exception to signal
+  # * RecordInvalid - raised by {ActiveRecord::Base#save}[rdoc-ref:Persistence#save] and
+  #   {ActiveRecord::Base.create!}[rdoc-ref:Persistence::ClassMethods#create!]
+  #   when the record is invalid.
+  # * RecordNotFound - No record responded to the {ActiveRecord::Base.find}[rdoc-ref:FinderMethods#find] method.
+  #   Either the row with the given ID doesn't exist or the row didn't meet the additional restrictions.
+  #   Some {ActiveRecord::Base.find}[rdoc-ref:FinderMethods#find] calls do not raise this exception to signal
   #   nothing was found, please check its documentation for further details.
   # * SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter.
   # * StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message.
@@ -282,6 +288,7 @@ module ActiveRecord #:nodoc:
     extend Explain
     extend Enum
     extend Delegation::DelegateCache
+    extend CollectionCacheKey
 
     include Core
     include Persistence
@@ -309,10 +316,12 @@ module ActiveRecord #:nodoc:
     include Aggregations
     include Transactions
     include NoTouching
+    include TouchLater
     include Reflection
     include Serialization
     include Store
     include SecureToken
+    include Suppressor
   end
 
   ActiveSupport.run_load_hooks(:active_record, Base)
diff --git a/activerecord/lib/active_record/callbacks.rb b/activerecord/lib/active_record/callbacks.rb
index 07769e8952..cfd8cbda67 100644
--- a/activerecord/lib/active_record/callbacks.rb
+++ b/activerecord/lib/active_record/callbacks.rb
@@ -1,11 +1,11 @@
 module ActiveRecord
-  # = Active Record Callbacks
+  # = Active Record \Callbacks
   #
-  # Callbacks are hooks into the life cycle of an Active Record object that allow you to trigger logic
+  # \Callbacks are hooks into the life cycle of an Active Record object that allow you to trigger logic
   # before or after an alteration of the object state. This can be used to make sure that associated and
-  # dependent objects are deleted when +destroy+ is called (by overwriting +before_destroy+) or to massage attributes
-  # before they're validated (by overwriting +before_validation+). As an example of the callbacks initiated, consider
-  # the <tt>Base#save</tt> call for a new record:
+  # dependent objects are deleted when {ActiveRecord::Base#destroy}[rdoc-ref:Persistence#destroy] is called (by overwriting +before_destroy+) or
+  # to massage attributes before they're validated (by overwriting +before_validation+).
+  # As an example of the callbacks initiated, consider the {ActiveRecord::Base#save}[rdoc-ref:Persistence#save] call for a new record:
   #
   # * (-) <tt>save</tt>
   # * (-) <tt>valid</tt>
@@ -20,7 +20,7 @@ module ActiveRecord
   # * (7) <tt>after_commit</tt>
   #
   # Also, an <tt>after_rollback</tt> callback can be configured to be triggered whenever a rollback is issued.
-  # Check out <tt>ActiveRecord::Transactions</tt> for more details about <tt>after_commit</tt> and
+  # Check out ActiveRecord::Transactions for more details about <tt>after_commit</tt> and
   # <tt>after_rollback</tt>.
   #
   # Additionally, an <tt>after_touch</tt> callback is triggered whenever an
@@ -31,7 +31,7 @@ module ActiveRecord
   # are instantiated as well.
   #
   # There are nineteen callbacks in total, which give you immense power to react and prepare for each state in the
-  # Active Record life cycle. The sequence for calling <tt>Base#save</tt> for an existing record is similar,
+  # Active Record life cycle. The sequence for calling {ActiveRecord::Base#save}[rdoc-ref:Persistence#save] for an existing record is similar,
   # except that each <tt>_create</tt> callback is replaced by the corresponding <tt>_update</tt> callback.
   #
   # Examples:
@@ -193,8 +193,9 @@ module ActiveRecord
   # == <tt>before_validation*</tt> returning statements
   #
   # If the +before_validation+ callback throws +:abort+, the process will be
-  # aborted and <tt>Base#save</tt> will return +false+. If Base#save! is called it will raise a
-  # ActiveRecord::RecordInvalid exception. Nothing will be appended to the errors object.
+  # aborted and {ActiveRecord::Base#save}[rdoc-ref:Persistence#save] will return +false+.
+  # If {ActiveRecord::Base#save!}[rdoc-ref:Persistence#save!] is called it will raise a ActiveRecord::RecordInvalid exception.
+  # Nothing will be appended to the errors object.
   #
   # == Canceling callbacks
   #
@@ -206,7 +207,8 @@ module ActiveRecord
   # == Ordering callbacks
   #
   # Sometimes the code needs that the callbacks execute in a specific order. For example, a +before_destroy+
-  # callback (+log_children+ in this case) should be executed before the children get destroyed by the +dependent: destroy+ option.
+  # callback (+log_children+ in this case) should be executed before the children get destroyed by the
+  # <tt>dependent: destroy</tt> option.
   #
   # Let's look at the code below:
   #
@@ -222,7 +224,8 @@ module ActiveRecord
   #   end
   #
   # In this case, the problem is that when the +before_destroy+ callback is executed, the children are not available
-  # because the +destroy+ callback gets executed first. You can use the +prepend+ option on the +before_destroy+ callback to avoid this.
+  # because the {ActiveRecord::Base#destroy}[rdoc-ref:Persistence#destroy] callback gets executed first.
+  # You can use the +prepend+ option on the +before_destroy+ callback to avoid this.
   #
   #   class Topic < ActiveRecord::Base
   #     has_many :children, dependent: destroy
@@ -237,21 +240,21 @@ module ActiveRecord
   #
   # This way, the +before_destroy+ gets executed before the <tt>dependent: destroy</tt> is called, and the data is still available.
   #
-  # == Transactions
+  # == \Transactions
   #
-  # The entire callback chain of a +save+, <tt>save!</tt>, or +destroy+ call runs
-  # within a transaction. That includes <tt>after_*</tt> hooks. If everything
-  # goes fine a COMMIT is executed once the chain has been completed.
+  # The entire callback chain of a {#save}[rdoc-ref:Persistence#save], {#save!}[rdoc-ref:Persistence#save!],
+  # or {#destroy}[rdoc-ref:Persistence#destroy] call runs within a transaction. That includes <tt>after_*</tt> hooks.
+  # If everything goes fine a COMMIT is executed once the chain has been completed.
   #
   # If a <tt>before_*</tt> callback cancels the action a ROLLBACK is issued. You
   # can also trigger a ROLLBACK raising an exception in any of the callbacks,
   # including <tt>after_*</tt> hooks. Note, however, that in that case the client
-  # needs to be aware of it because an ordinary +save+ will raise such exception
+  # needs to be aware of it because an ordinary {#save}[rdoc-ref:Persistence#save] will raise such exception
   # instead of quietly returning +false+.
   #
   # == Debugging callbacks
   #
-  # The callback chain is accessible via the <tt>_*_callbacks</tt> method on an object. ActiveModel Callbacks support
+  # The callback chain is accessible via the <tt>_*_callbacks</tt> method on an object. Active Model \Callbacks support
   # <tt>:before</tt>, <tt>:after</tt> and <tt>:around</tt> as values for the <tt>kind</tt> property. The <tt>kind</tt> property
   # defines what part of the chain the callback runs in.
   #
@@ -277,7 +280,7 @@ module ActiveRecord
       :before_destroy, :around_destroy, :after_destroy, :after_commit, :after_rollback
     ]
 
-    module ClassMethods
+    module ClassMethods # :nodoc:
       include ActiveModel::Callbacks
     end
 
@@ -289,14 +292,15 @@ module ActiveRecord
     end
 
     def destroy #:nodoc:
-      begin
-        @_destroy_callback_already_called ||= false
-        return if @_destroy_callback_already_called
-        @_destroy_callback_already_called = true
-        _run_destroy_callbacks { super }
-      ensure
-        @_destroy_callback_already_called = false
-      end
+      @_destroy_callback_already_called ||= false
+      return if @_destroy_callback_already_called
+      @_destroy_callback_already_called = true
+      _run_destroy_callbacks { super }
+    rescue RecordNotDestroyed => e
+      @_association_destroy_exception = e
+      false
+    ensure
+      @_destroy_callback_already_called = false
     end
 
     def touch(*) #:nodoc:
diff --git a/activerecord/lib/active_record/coders/yaml_column.rb b/activerecord/lib/active_record/coders/yaml_column.rb
index 9ea22ed798..2456b8ad8c 100644
--- a/activerecord/lib/active_record/coders/yaml_column.rb
+++ b/activerecord/lib/active_record/coders/yaml_column.rb
@@ -14,10 +14,7 @@ module ActiveRecord
       def dump(obj)
         return if obj.nil?
 
-        unless obj.is_a?(object_class)
-          raise SerializationTypeMismatch,
-            "Attribute was supposed to be a #{object_class}, but was a #{obj.class}. -- #{obj.inspect}"
-        end
+        assert_valid_value(obj)
         YAML.dump obj
       end
 
@@ -26,15 +23,19 @@ module ActiveRecord
         return yaml unless yaml.is_a?(String) && yaml =~ /^---/
         obj = YAML.load(yaml)
 
-        unless obj.is_a?(object_class) || obj.nil?
-          raise SerializationTypeMismatch,
-            "Attribute was supposed to be a #{object_class}, but was a #{obj.class}"
-        end
+        assert_valid_value(obj)
         obj ||= object_class.new if object_class != Object
 
         obj
       end
 
+      def assert_valid_value(obj)
+        unless obj.nil? || obj.is_a?(object_class)
+          raise SerializationTypeMismatch,
+            "Attribute was supposed to be a #{object_class}, but was a #{obj.class}. -- #{obj.inspect}"
+        end
+      end
+
       private
 
       def check_arity_of_constructor
diff --git a/activerecord/lib/active_record/collection_cache_key.rb b/activerecord/lib/active_record/collection_cache_key.rb
new file mode 100644
index 0000000000..3c4ca3d116
--- /dev/null
+++ b/activerecord/lib/active_record/collection_cache_key.rb
@@ -0,0 +1,31 @@
+module ActiveRecord
+  module CollectionCacheKey
+
+    def collection_cache_key(collection = all, timestamp_column = :updated_at) # :nodoc:
+      query_signature = Digest::MD5.hexdigest(collection.to_sql)
+      key = "#{collection.model_name.cache_key}/query-#{query_signature}"
+
+      if collection.loaded?
+        size = collection.size
+        timestamp = collection.max_by(&timestamp_column).public_send(timestamp_column)
+      else
+        column_type = type_for_attribute(timestamp_column.to_s)
+        column = "#{connection.quote_table_name(collection.table_name)}.#{connection.quote_column_name(timestamp_column)}"
+
+        query = collection
+          .select("COUNT(*) AS size", "MAX(#{column}) AS timestamp")
+          .unscope(:order)
+        result = connection.select_one(query)
+
+        size = result["size"]
+        timestamp = column_type.deserialize(result["timestamp"])
+      end
+
+      if timestamp
+        "#{key}-#{size}-#{timestamp.utc.to_s(cache_timestamp_format)}"
+      else
+        "#{key}-#{size}"
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
index d99dc9a5db..0d850c7625 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -1,7 +1,6 @@
 require 'thread'
-require 'thread_safe'
+require 'concurrent'
 require 'monitor'
-require 'set'
 
 module ActiveRecord
   # Raised when a connection could not be obtained within the connection
@@ -10,6 +9,13 @@ module ActiveRecord
   class ConnectionTimeoutError < ConnectionNotEstablished
   end
 
+  # Raised when a pool was unable to get ahold of all its connections
+  # to perform a "group" action such as
+  # {ActiveRecord::Base.connection_pool.disconnect!}[rdoc-ref:ConnectionAdapters::ConnectionPool#disconnect!]
+  # or {ActiveRecord::Base.clear_reloadable_connections!}[rdoc-ref:ConnectionAdapters::ConnectionHandler#clear_reloadable_connections!].
+  class ExclusiveConnectionTimeoutError < ConnectionTimeoutError
+  end
+
   module ConnectionAdapters
     # Connection pool base class for managing Active Record database
     # connections.
@@ -32,17 +38,18 @@ module ActiveRecord
     # Connections can be obtained and used from a connection pool in several
     # ways:
     #
-    # 1. Simply use ActiveRecord::Base.connection as with Active Record 2.1 and
+    # 1. Simply use {ActiveRecord::Base.connection}[rdoc-ref:ConnectionHandling.connection]
+    #    as with Active Record 2.1 and
     #    earlier (pre-connection-pooling). Eventually, when you're done with
     #    the connection(s) and wish it to be returned to the pool, you call
-    #    ActiveRecord::Base.clear_active_connections!. This will be the
-    #    default behavior for Active Record when used in conjunction with
+    #    {ActiveRecord::Base.clear_active_connections!}[rdoc-ref:ConnectionAdapters::ConnectionHandler#clear_active_connections!].
+    #    This will be the default behavior for Active Record when used in conjunction with
     #    Action Pack's request handling cycle.
     # 2. Manually check out a connection from the pool with
-    #    ActiveRecord::Base.connection_pool.checkout. You are responsible for
+    #    {ActiveRecord::Base.connection_pool.checkout}[rdoc-ref:#checkout]. You are responsible for
     #    returning this connection to the pool when finished by calling
-    #    ActiveRecord::Base.connection_pool.checkin(connection).
-    # 3. Use ActiveRecord::Base.connection_pool.with_connection(&block), which
+    #    {ActiveRecord::Base.connection_pool.checkin(connection)}[rdoc-ref:#checkin].
+    # 3. Use {ActiveRecord::Base.connection_pool.with_connection(&block)}[rdoc-ref:#with_connection], which
     #    obtains a connection, yields it as the sole argument to the block,
     #    and returns it to the pool after the block completes.
     #
@@ -63,6 +70,15 @@ module ActiveRecord
     #   connection at the end of a thread or a thread dies unexpectedly.
     #   Regardless of this setting, the Reaper will be invoked before every
     #   blocking wait. (Default nil, which means don't schedule the Reaper).
+    #
+    #--
+    # Synchronization policy:
+    # * all public methods can be called outside +synchronize+
+    # * access to these i-vars needs to be in +synchronize+:
+    #   * @connections
+    #   * @now_connecting
+    # * private methods that require being called in a +synchronize+ blocks
+    #   are now explicitly documented
     class ConnectionPool
       # Threadsafe, fair, FIFO queue.  Meant to be used by ConnectionPool
       # with which it shares a Monitor.  But could be a generic Queue.
@@ -126,20 +142,18 @@ module ActiveRecord
         # become available.
         #
         # Raises:
-        # - ConnectionTimeoutError if +timeout+ is given and no element
+        # - ActiveRecord::ConnectionTimeoutError if +timeout+ is given and no element
         # becomes available within +timeout+ seconds,
         def poll(timeout = nil)
-          synchronize do
-            if timeout
-              no_wait_poll || wait_poll(timeout)
-            else
-              no_wait_poll
-            end
-          end
+          synchronize { internal_poll(timeout) }
         end
 
         private
 
+        def internal_poll(timeout)
+          no_wait_poll || (timeout && wait_poll(timeout))
+        end
+
         def synchronize(&block)
           @lock.synchronize(&block)
         end
@@ -193,6 +207,80 @@ module ActiveRecord
         end
       end
 
+      # Adds the ability to turn a basic fair FIFO queue into one
+      # biased to some thread.
+      module BiasableQueue # :nodoc:
+        class BiasedConditionVariable # :nodoc:
+          # semantics of condition variables guarantee that +broadcast+, +broadcast_on_biased+,
+          # +signal+ and +wait+ methods are only called while holding a lock
+          def initialize(lock, other_cond, preferred_thread)
+            @real_cond = lock.new_cond
+            @other_cond = other_cond
+            @preferred_thread = preferred_thread
+            @num_waiting_on_real_cond = 0
+          end
+
+          def broadcast
+            broadcast_on_biased
+            @other_cond.broadcast
+          end
+
+          def broadcast_on_biased
+            @num_waiting_on_real_cond = 0
+            @real_cond.broadcast
+          end
+
+          def signal
+            if @num_waiting_on_real_cond > 0
+              @num_waiting_on_real_cond -= 1
+              @real_cond
+            else
+              @other_cond
+            end.signal
+          end
+
+          def wait(timeout)
+            if Thread.current == @preferred_thread
+              @num_waiting_on_real_cond += 1
+              @real_cond
+            else
+              @other_cond
+            end.wait(timeout)
+          end
+        end
+
+        def with_a_bias_for(thread)
+          previous_cond = nil
+          new_cond      = nil
+          synchronize do
+            previous_cond = @cond
+            @cond = new_cond = BiasedConditionVariable.new(@lock, @cond, thread)
+          end
+          yield
+        ensure
+          synchronize do
+            @cond = previous_cond if previous_cond
+            new_cond.broadcast_on_biased if new_cond # wake up any remaining sleepers
+          end
+        end
+      end
+
+      # Connections must be leased while holding the main pool mutex. This is
+      # an internal subclass that also +.leases+ returned connections while
+      # still in queue's critical section (queue synchronizes with the same
+      # +@lock+ as the main pool) so that a returned connection is already
+      # leased and there is no need to re-enter synchronized block.
+      class ConnectionLeasingQueue < Queue # :nodoc:
+        include BiasableQueue
+
+        private
+        def internal_poll(timeout)
+          conn = super
+          conn.lease if conn
+          conn
+        end
+      end
+
       # Every +frequency+ seconds, the reaper will call +reap+ on +pool+.
       # A reaper instantiated with a nil frequency will never reap the
       # connection pool.
@@ -220,7 +308,7 @@ module ActiveRecord
 
       include MonitorMixin
 
-      attr_accessor :automatic_reconnect, :checkout_timeout
+      attr_accessor :automatic_reconnect, :checkout_timeout, :schema_cache
       attr_reader :spec, :connections, :size, :reaper
 
       # Creates a new ConnectionPool object. +spec+ is a ConnectionSpecification
@@ -241,56 +329,75 @@ module ActiveRecord
         # default max pool size to 5
         @size = (spec.config[:pool] && spec.config[:pool].to_i) || 5
 
-        # The cache of reserved connections mapped to threads
-        @reserved_connections = ThreadSafe::Cache.new(:initial_capacity => @size)
+        # The cache of threads mapped to reserved connections, the sole purpose
+        # of the cache is to speed-up +connection+ method, it is not the authoritative
+        # registry of which thread owns which connection, that is tracked by
+        # +connection.owner+ attr on each +connection+ instance.
+        # The invariant works like this: if there is mapping of <tt>thread => conn</tt>,
+        # then that +thread+ does indeed own that +conn+, however an absence of a such
+        # mapping does not mean that the +thread+ doesn't own the said connection, in
+        # that case +conn.owner+ attr should be consulted.
+        # Access and modification of +@thread_cached_conns+ does not require
+        # synchronization.
+        @thread_cached_conns = Concurrent::Map.new(:initial_capacity => @size)
 
         @connections         = []
         @automatic_reconnect = true
 
-        @available = Queue.new self
+        # Connection pool allows for concurrent (outside the main +synchronize+ section)
+        # establishment of new connections. This variable tracks the number of threads
+        # currently in the process of independently establishing connections to the DB.
+        @now_connecting = 0
+
+        # A boolean toggle that allows/disallows new connections.
+        @new_cons_enabled = true
+
+        @available = ConnectionLeasingQueue.new self
       end
 
       # Retrieve the connection associated with the current thread, or call
       # #checkout to obtain one if necessary.
       #
       # #connection can be called any number of times; the connection is
-      # held in a hash keyed by the thread id.
+      # held in a cache keyed by a thread.
       def connection
-        # this is correctly done double-checked locking
-        # (ThreadSafe::Cache's lookups have volatile semantics)
-        @reserved_connections[current_connection_id] || synchronize do
-          @reserved_connections[current_connection_id] ||= checkout
-        end
+        @thread_cached_conns[connection_cache_key(Thread.current)] ||= checkout
       end
 
       # Is there an open connection that is being used for the current thread?
+      #
+      # This method only works for connections that have been obtained through
+      # #connection or #with_connection methods, connections obtained through
+      # #checkout will not be detected by #active_connection?
       def active_connection?
-        synchronize do
-          @reserved_connections.fetch(current_connection_id) {
-            return false
-          }.in_use?
-        end
+        @thread_cached_conns[connection_cache_key(Thread.current)]
       end
 
       # Signal that the thread is finished with the current connection.
       # #release_connection releases the connection-thread association
       # and returns the connection to the pool.
-      def release_connection(with_id = current_connection_id)
-        synchronize do
-          conn = @reserved_connections.delete(with_id)
-          checkin conn if conn
+      #
+      # This method only works for connections that have been obtained through
+      # #connection or #with_connection methods, connections obtained through
+      # #checkout will not be automatically released.
+      def release_connection(owner_thread = Thread.current)
+        if conn = @thread_cached_conns.delete(connection_cache_key(owner_thread))
+          checkin conn
         end
       end
 
-      # If a connection already exists yield it to the block. If no connection
+      # If a connection obtained through #connection or #with_connection methods
+      # already exists yield it to the block. If no such connection
       # exists checkout a connection, yield it to the block, and checkin the
       # connection when finished.
       def with_connection
-        connection_id = current_connection_id
-        fresh_connection = true unless active_connection?
-        yield connection
+        unless conn = @thread_cached_conns[connection_cache_key(Thread.current)]
+          conn = connection
+          fresh_connection = true
+        end
+        yield conn
       ensure
-        release_connection(connection_id) if fresh_connection
+        release_connection if fresh_connection
       end
 
       # Returns true if a connection has already been opened.
@@ -299,32 +406,81 @@ module ActiveRecord
       end
 
       # Disconnects all connections in the pool, and clears the pool.
-      def disconnect!
-        synchronize do
-          @reserved_connections.clear
-          @connections.each do |conn|
-            checkin conn
-            conn.disconnect!
+      #
+      # Raises:
+      # - ActiveRecord::ExclusiveConnectionTimeoutError if unable to gain ownership of all
+      #   connections in the pool within a timeout interval (default duration is
+      #   <tt>spec.config[:checkout_timeout] * 2</tt> seconds).
+      def disconnect(raise_on_acquisition_timeout = true)
+        with_exclusively_acquired_all_connections(raise_on_acquisition_timeout) do
+          synchronize do
+            @connections.each do |conn|
+              checkin conn
+              conn.disconnect!
+            end
+            @connections = []
+            @available.clear
           end
-          @connections = []
-          @available.clear
         end
       end
 
-      # Clears the cache which maps classes.
-      def clear_reloadable_connections!
-        synchronize do
-          @reserved_connections.clear
-          @connections.each do |conn|
-            checkin conn
-            conn.disconnect! if conn.requires_reloading?
-          end
-          @connections.delete_if(&:requires_reloading?)
-          @available.clear
-          @connections.each do |conn|
-            @available.add conn
+      # Disconnects all connections in the pool, and clears the pool.
+      #
+      # The pool first tries to gain ownership of all connections, if unable to
+      # do so within a timeout interval (default duration is
+      # <tt>spec.config[:checkout_timeout] * 2</tt> seconds), the pool is forcefully
+      # disconnected without any regard for other connection owning threads.
+      def disconnect!
+        disconnect(false)
+      end
+
+      # Clears the cache which maps classes and re-connects connections that
+      # require reloading.
+      #
+      # Raises:
+      # - ActiveRecord::ExclusiveConnectionTimeoutError if unable to gain ownership of all
+      #   connections in the pool within a timeout interval (default duration is
+      #   <tt>spec.config[:checkout_timeout] * 2</tt> seconds).
+      def clear_reloadable_connections(raise_on_acquisition_timeout = true)
+        num_new_conns_required = 0
+
+        with_exclusively_acquired_all_connections(raise_on_acquisition_timeout) do
+          synchronize do
+            @connections.each do |conn|
+              checkin conn
+              conn.disconnect! if conn.requires_reloading?
+            end
+            @connections.delete_if(&:requires_reloading?)
+
+            @available.clear
+
+            if @connections.size < @size
+              # because of the pruning done by this method, we might be running
+              # low on connections, while threads stuck in queue are helpless
+              # (not being able to establish new connections for themselves),
+              # see also more detailed explanation in +remove+
+              num_new_conns_required = num_waiting_in_queue - @connections.size
+            end
+
+            @connections.each do |conn|
+              @available.add conn
+            end
           end
         end
+
+        bulk_make_new_connections(num_new_conns_required) if num_new_conns_required > 0
+      end
+
+      # Clears the cache which maps classes and re-connects connections that
+      # require reloading.
+      #
+      # The pool first tries to gain ownership of all connections, if unable to
+      # do so within a timeout interval (default duration is
+      # <tt>spec.config[:checkout_timeout] * 2</tt> seconds), the pool forcefully
+      # clears the cache and reloads connections without any regard for other
+      # connection owning threads.
+      def clear_reloadable_connections!
+        clear_reloadable_connections(false)
       end
 
       # Check-out a database connection from the pool, indicating that you want
@@ -340,48 +496,60 @@ module ActiveRecord
       # Returns: an AbstractAdapter object.
       #
       # Raises:
-      # - ConnectionTimeoutError: no connection can be obtained from the pool.
-      def checkout
-        synchronize do
-          conn = acquire_connection
-          conn.lease
-          checkout_and_verify(conn)
-        end
+      # - ActiveRecord::ConnectionTimeoutError no connection can be obtained from the pool.
+      def checkout(checkout_timeout = @checkout_timeout)
+        checkout_and_verify(acquire_connection(checkout_timeout))
       end
 
       # Check-in a database connection back into the pool, indicating that you
       # no longer need this connection.
       #
       # +conn+: an AbstractAdapter object, which was obtained by earlier by
-      # calling +checkout+ on this pool.
+      # calling #checkout on this pool.
       def checkin(conn)
         synchronize do
-          owner = conn.owner
+          remove_connection_from_thread_cache conn
 
           conn._run_checkin_callbacks do
             conn.expire
           end
 
-          release conn, owner
-
           @available.add conn
         end
       end
 
-      # Remove a connection from the connection pool.  The connection will
+      # Remove a connection from the connection pool. The connection will
       # remain open and active but will no longer be managed by this pool.
       def remove(conn)
+        needs_new_connection = false
+
         synchronize do
+          remove_connection_from_thread_cache conn
+
           @connections.delete conn
           @available.delete conn
 
-          release conn, conn.owner
-
-          @available.add checkout_new_connection if @available.any_waiting?
+          # @available.any_waiting? => true means that prior to removing this
+          # conn, the pool was at its max size (@connections.size == @size)
+          # this would mean that any threads stuck waiting in the queue wouldn't
+          # know they could checkout_new_connection, so let's do it for them.
+          # Because condition-wait loop is encapsulated in the Queue class
+          # (that in turn is oblivious to ConnectionPool implementation), threads
+          # that are "stuck" there are helpless, they have no way of creating
+          # new connections and are completely reliant on us feeding available
+          # connections into the Queue.
+          needs_new_connection = @available.any_waiting?
         end
+
+        # This is intentionally done outside of the synchronized section as we
+        # would like not to hold the main mutex while checking out new connections,
+        # thus there is some chance that needs_new_connection information is now
+        # stale, we can live with that (bulk_make_new_connections will make
+        # sure not to exceed the pool's @size limit).
+        bulk_make_new_connections(1) if needs_new_connection
       end
 
-      # Recover lost connections for the pool.  A lost connection can occur if
+      # Recover lost connections for the pool. A lost connection can occur if
       # a programmer forgets to checkin a connection at the end of a thread
       # or a thread dies unexpectedly.
       def reap
@@ -403,7 +571,118 @@ module ActiveRecord
         end
       end
 
+      def num_waiting_in_queue # :nodoc:
+        @available.num_waiting
+      end
+
       private
+      #--
+      # this is unfortunately not concurrent
+      def bulk_make_new_connections(num_new_conns_needed)
+        num_new_conns_needed.times do
+          # try_to_checkout_new_connection will not exceed pool's @size limit
+          if new_conn = try_to_checkout_new_connection
+            # make the new_conn available to the starving threads stuck @available Queue
+            checkin(new_conn)
+          end
+        end
+      end
+
+      #--
+      # From the discussion on GitHub:
+      #  https://github.com/rails/rails/pull/14938#commitcomment-6601951
+      # This hook-in method allows for easier monkey-patching fixes needed by
+      # JRuby users that use Fibers.
+      def connection_cache_key(thread)
+        thread
+      end
+
+      # Take control of all existing connections so a "group" action such as
+      # reload/disconnect can be performed safely. It is no longer enough to
+      # wrap it in +synchronize+ because some pool's actions are allowed
+      # to be performed outside of the main +synchronize+ block.
+      def with_exclusively_acquired_all_connections(raise_on_acquisition_timeout = true)
+        with_new_connections_blocked do
+          attempt_to_checkout_all_existing_connections(raise_on_acquisition_timeout)
+          yield
+        end
+      end
+
+      def attempt_to_checkout_all_existing_connections(raise_on_acquisition_timeout = true)
+        collected_conns = synchronize do
+          # account for our own connections
+          @connections.select {|conn| conn.owner == Thread.current}
+        end
+
+        newly_checked_out = []
+        timeout_time      = Time.now + (@checkout_timeout * 2)
+
+        @available.with_a_bias_for(Thread.current) do
+          while true
+            synchronize do
+              return if collected_conns.size == @connections.size && @now_connecting == 0
+              remaining_timeout = timeout_time - Time.now
+              remaining_timeout = 0 if remaining_timeout < 0
+              conn = checkout_for_exclusive_access(remaining_timeout)
+              collected_conns   << conn
+              newly_checked_out << conn
+            end
+          end
+        end
+      rescue ExclusiveConnectionTimeoutError
+        # <tt>raise_on_acquisition_timeout == false</tt> means we are directed to ignore any
+        # timeouts and are expected to just give up: we've obtained as many connections
+        # as possible, note that in a case like that we don't return any of the
+        # +newly_checked_out+ connections.
+
+        if raise_on_acquisition_timeout
+          release_newly_checked_out = true
+          raise
+        end
+      rescue Exception # if something else went wrong
+        # this can't be a "naked" rescue, because we have should return conns
+        # even for non-StandardErrors
+        release_newly_checked_out = true
+        raise
+      ensure
+        if release_newly_checked_out && newly_checked_out
+          # releasing only those conns that were checked out in this method, conns
+          # checked outside this method (before it was called) are not for us to release
+          newly_checked_out.each {|conn| checkin(conn)}
+        end
+      end
+
+      #--
+      # Must be called in a synchronize block.
+      def checkout_for_exclusive_access(checkout_timeout)
+        checkout(checkout_timeout)
+      rescue ConnectionTimeoutError
+        # this block can't be easily moved into attempt_to_checkout_all_existing_connections's
+        # rescue block, because doing so would put it outside of synchronize section, without
+        # being in a critical section thread_report might become inaccurate
+        msg = "could not obtain ownership of all database connections in #{checkout_timeout} seconds"
+
+        thread_report = []
+        @connections.each do |conn|
+          unless conn.owner == Thread.current
+            thread_report << "#{conn} is owned by #{conn.owner}"
+          end
+        end
+
+        msg << " (#{thread_report.join(', ')})" if thread_report.any?
+
+        raise ExclusiveConnectionTimeoutError, msg
+      end
+
+      def with_new_connections_blocked
+        previous_value = nil
+        synchronize do
+          previous_value, @new_cons_enabled = @new_cons_enabled, false
+        end
+        yield
+      ensure
+        synchronize { @new_cons_enabled = previous_value }
+      end
 
       # Acquire a connection by one of 1) immediately removing one
       # from the queue of available connections, 2) creating a new
@@ -411,41 +690,79 @@ module ActiveRecord
       # queue for a connection to become available.
       #
       # Raises:
-      # - ConnectionTimeoutError if a connection could not be acquired
-      def acquire_connection
-        if conn = @available.poll
+      # - ActiveRecord::ConnectionTimeoutError if a connection could not be acquired
+      #
+      #--
+      # Implementation detail: the connection returned by +acquire_connection+
+      # will already be "+connection.lease+ -ed" to the current thread.
+      def acquire_connection(checkout_timeout)
+        # NOTE: we rely on +@available.poll+ and +try_to_checkout_new_connection+ to
+        # +conn.lease+ the returned connection (and to do this in a +synchronized+
+        # section), this is not the cleanest implementation, as ideally we would
+        # <tt>synchronize { conn.lease }</tt> in this method, but by leaving it to +@available.poll+
+        # and +try_to_checkout_new_connection+ we can piggyback on +synchronize+ sections
+        # of the said methods and avoid an additional +synchronize+ overhead.
+        if conn = @available.poll || try_to_checkout_new_connection
           conn
-        elsif @connections.size < @size
-          checkout_new_connection
         else
           reap
-          @available.poll(@checkout_timeout)
+          @available.poll(checkout_timeout)
         end
       end
 
-      def release(conn, owner)
-        thread_id = owner.object_id
-
-        if @reserved_connections[thread_id] == conn
-          @reserved_connections.delete thread_id
-        end
+      #--
+      # if owner_thread param is omitted, this must be called in synchronize block
+      def remove_connection_from_thread_cache(conn, owner_thread = conn.owner)
+        @thread_cached_conns.delete_pair(connection_cache_key(owner_thread), conn)
       end
+      alias_method :release, :remove_connection_from_thread_cache
 
       def new_connection
-        Base.send(spec.adapter_method, spec.config)
+        Base.send(spec.adapter_method, spec.config).tap do |conn|
+          conn.schema_cache = schema_cache.dup if schema_cache
+        end
+      end
+
+      # If the pool is not at a +@size+ limit, establish new connection. Connecting
+      # to the DB is done outside main synchronized section.
+      #--
+      # Implementation constraint: a newly established connection returned by this
+      # method must be in the +.leased+ state.
+      def try_to_checkout_new_connection
+        # first in synchronized section check if establishing new conns is allowed
+        # and increment @now_connecting, to prevent overstepping this pool's @size
+        # constraint
+        do_checkout = synchronize do
+          if @new_cons_enabled && (@connections.size + @now_connecting) < @size
+            @now_connecting += 1
+          end
+        end
+        if do_checkout
+          begin
+            # if successfully incremented @now_connecting establish new connection
+            # outside of synchronized section
+            conn = checkout_new_connection
+          ensure
+            synchronize do
+              if conn
+                adopt_connection(conn)
+                # returned conn needs to be already leased
+                conn.lease
+              end
+              @now_connecting -= 1
+            end
+          end
+        end
       end
 
-      def current_connection_id #:nodoc:
-        Base.connection_id ||= Thread.current.object_id
+      def adopt_connection(conn)
+        conn.pool = self
+        @connections << conn
       end
 
       def checkout_new_connection
         raise ConnectionNotEstablished unless @automatic_reconnect
-
-        c = new_connection
-        c.pool = self
-        @connections << c
-        c
+        new_connection
       end
 
       def checkout_and_verify(c)
@@ -509,11 +826,11 @@ module ActiveRecord
         # These caches are keyed by klass.name, NOT klass. Keying them by klass
         # alone would lead to memory leaks in development mode as all previous
         # instances of the class would stay in memory.
-        @owner_to_pool = ThreadSafe::Cache.new(:initial_capacity => 2) do |h,k|
-          h[k] = ThreadSafe::Cache.new(:initial_capacity => 2)
+        @owner_to_pool = Concurrent::Map.new(:initial_capacity => 2) do |h,k|
+          h[k] = Concurrent::Map.new(:initial_capacity => 2)
         end
-        @class_to_pool = ThreadSafe::Cache.new(:initial_capacity => 2) do |h,k|
-          h[k] = ThreadSafe::Cache.new
+        @class_to_pool = Concurrent::Map.new(:initial_capacity => 2) do |h,k|
+          h[k] = Concurrent::Map.new
         end
       end
 
@@ -542,6 +859,8 @@ module ActiveRecord
       end
 
       # Clears the cache which maps classes.
+      #
+      # See ConnectionPool#clear_reloadable_connections! for details.
       def clear_reloadable_connections!
         connection_pool_list.each(&:clear_reloadable_connections!)
       end
@@ -618,7 +937,9 @@ module ActiveRecord
             # A connection was established in an ancestor process that must have
             # subsequently forked. We can't reuse the connection, but we can copy
             # the specification and establish a new connection with it.
-            establish_connection owner, ancestor_pool.spec
+            establish_connection(owner, ancestor_pool.spec).tap do |pool|
+              pool.schema_cache = ancestor_pool.schema_cache if ancestor_pool.schema_cache
+            end
           else
             owner_to_pool[owner.name] = nil
           end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb b/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb
index c0a2111571..6711049588 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb
@@ -18,9 +18,9 @@ module ActiveRecord
       end
 
       # Returns the maximum allowed length for an index name. This
-      # limit is enforced by rails and Is less than or equal to
-      # <tt>index_name_length</tt>. The gap between
-      # <tt>index_name_length</tt> is to allow internal rails
+      # limit is enforced by \Rails and is less than or equal to
+      # #index_name_length. The gap between
+      # #index_name_length is to allow internal \Rails
       # operations to use prefixes in temporary operations.
       def allowed_index_name_length
         index_name_length
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
index 787d07c4c2..848aeb821c 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -29,7 +29,17 @@ module ActiveRecord
       # Returns an ActiveRecord::Result instance.
       def select_all(arel, name = nil, binds = [])
         arel, binds = binds_from_relation arel, binds
-        select(to_sql(arel, binds), name, binds)
+        sql = to_sql(arel, binds)
+        if arel.is_a?(String)
+          preparable = false
+        else
+          preparable = visitor.preparable
+        end
+        if prepared_statements && preparable
+          select_prepared(sql, name, binds)
+        else
+          select(sql, name, binds)
+        end
       end
 
       # Returns a record hash with the column names as keys and column values
@@ -40,8 +50,9 @@ module ActiveRecord
 
       # Returns a single value from a record
       def select_value(arel, name = nil, binds = [])
-        if result = select_one(arel, name, binds)
-          result.values.first
+        arel, binds = binds_from_relation arel, binds
+        if result = select_rows(to_sql(arel, binds), name, binds).first
+          result.first
         end
       end
 
@@ -66,7 +77,7 @@ module ActiveRecord
       # Executes +sql+ statement in the context of this connection using
       # +binds+ as the bind substitutes. +name+ is logged along with
       # the executed +sql+ statement.
-      def exec_query(sql, name = 'SQL', binds = [])
+      def exec_query(sql, name = 'SQL', binds = [], prepare: false)
       end
 
       # Executes insert +sql+ statement in the context of this connection using
@@ -136,7 +147,7 @@ module ActiveRecord
       #
       # In order to get around this problem, #transaction will emulate the effect
       # of nested transactions, by using savepoints:
-      # http://dev.mysql.com/doc/refman/5.0/en/savepoint.html
+      # http://dev.mysql.com/doc/refman/5.7/en/savepoint.html
       # Savepoints are supported by MySQL and PostgreSQL. SQLite3 version >= '3.6.8'
       # supports savepoints.
       #
@@ -188,10 +199,10 @@ module ActiveRecord
       # You should consult the documentation for your database to understand the
       # semantics of these different levels:
       #
-      # * http://www.postgresql.org/docs/9.1/static/transaction-iso.html
-      # * https://dev.mysql.com/doc/refman/5.0/en/set-transaction.html
+      # * http://www.postgresql.org/docs/current/static/transaction-iso.html
+      # * https://dev.mysql.com/doc/refman/5.7/en/set-transaction.html
       #
-      # An <tt>ActiveRecord::TransactionIsolationError</tt> will be raised if:
+      # An ActiveRecord::TransactionIsolationError will be raised if:
       #
       # * The adapter does not support setting the isolation level
       # * You are joining an existing open transaction
@@ -201,16 +212,14 @@ module ActiveRecord
       # isolation level. However, support is disabled for MySQL versions below 5,
       # because they are affected by a bug[http://bugs.mysql.com/bug.php?id=39170]
       # which means the isolation level gets persisted outside the transaction.
-      def transaction(options = {})
-        options.assert_valid_keys :requires_new, :joinable, :isolation
-
-        if !options[:requires_new] && current_transaction.joinable?
-          if options[:isolation]
+      def transaction(requires_new: nil, isolation: nil, joinable: true)
+        if !requires_new && current_transaction.joinable?
+          if isolation
             raise ActiveRecord::TransactionIsolationError, "cannot set isolation when joining a transaction"
           end
           yield
         else
-          transaction_manager.within_new_transaction(options) { yield }
+          transaction_manager.within_new_transaction(isolation: isolation, joinable: joinable) { yield }
         end
       rescue ActiveRecord::Rollback
         # rollbacks are silently swallowed
@@ -234,6 +243,10 @@ module ActiveRecord
         current_transaction.add_record(record)
       end
 
+      def transaction_state
+        current_transaction.state
+      end
+
       # Begins the transaction (and turns off auto-committing).
       def begin_db_transaction()    end
 
@@ -286,10 +299,15 @@ module ActiveRecord
         columns = schema_cache.columns_hash(table_name)
 
         binds = fixture.map do |name, value|
-          [columns[name], value]
+          if column = columns[name]
+            type = lookup_cast_type_from_column(column)
+            Relation::QueryAttribute.new(name, value, type)
+          else
+            raise Fixture::FixtureError, %(table "#{table_name}" has no column named "#{name}".)
+          end
         end
         key_list = fixture.keys.map { |name| quote_column_name(name) }
-        value_list = prepare_binds_for_database(binds).map do |_, value|
+        value_list = prepare_binds_for_database(binds).map do |value|
           begin
             quote(value)
           rescue TypeError
@@ -350,9 +368,12 @@ module ActiveRecord
 
         # Returns an ActiveRecord::Result instance.
         def select(sql, name = nil, binds = [])
-          exec_query(sql, name, binds)
+          exec_query(sql, name, binds, prepare: false)
         end
 
+        def select_prepared(sql, name = nil, binds = [])
+          exec_query(sql, name, binds, prepare: true)
+        end
 
         # Returns the last auto-generated ID from the affected table.
         def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
@@ -381,7 +402,7 @@ module ActiveRecord
 
         def binds_from_relation(relation, binds)
           if relation.is_a?(Relation) && binds.empty?
-            relation, binds = relation.arel, relation.bind_values
+            relation, binds = relation.arel, relation.bound_attributes
           end
           [relation, binds]
         end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb b/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
index c18caa2a2f..9ec0a67c8f 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
@@ -16,7 +16,7 @@ module ActiveRecord
             https://github.com/rails/arel/commit/6160bfbda1d1781c3b08a33ec4955f170e95be11
             for more information.
           MSG
-          value = column.cast_type.type_cast_for_database(value)
+          value = type_cast_from_column(column, value)
         end
 
         _quote(value)
@@ -31,7 +31,7 @@ module ActiveRecord
         end
 
         if column
-          value = column.cast_type.type_cast_for_database(value)
+          value = type_cast_from_column(column, value)
         end
 
         _type_cast(value)
@@ -40,10 +40,44 @@ module ActiveRecord
         raise TypeError, "can't cast #{value.class}#{to_type}"
       end
 
+      # If you are having to call this function, you are likely doing something
+      # wrong. The column does not have sufficient type information if the user
+      # provided a custom type on the class level either explicitly (via
+      # Attributes::ClassMethods#attribute) or implicitly (via
+      # AttributeMethods::Serialization::ClassMethods#serialize, +time_zone_aware_attributes+).
+      # In almost all cases, the sql type should only be used to change quoting behavior, when the primitive to
+      # represent the type doesn't sufficiently reflect the differences
+      # (varchar vs binary) for example. The type used to get this primitive
+      # should have been provided before reaching the connection adapter.
+      def type_cast_from_column(column, value) # :nodoc:
+        if column
+          type = lookup_cast_type_from_column(column)
+          type.serialize(value)
+        else
+          value
+        end
+      end
+
+      # See docs for #type_cast_from_column
+      def lookup_cast_type_from_column(column) # :nodoc:
+        lookup_cast_type(column.sql_type)
+      end
+
+      def fetch_type_metadata(sql_type)
+        cast_type = lookup_cast_type(sql_type)
+        SqlTypeMetadata.new(
+          sql_type: sql_type,
+          type: cast_type.type,
+          limit: cast_type.limit,
+          precision: cast_type.precision,
+          scale: cast_type.scale,
+        )
+      end
+
       # Quotes a string, escaping any ' (single quote) and \ (backslash)
       # characters.
       def quote_string(s)
-        s.gsub(/\\/, '\&\&').gsub(/'/, "''") # ' (for ruby-mode)
+        s.gsub('\\'.freeze, '\&\&'.freeze).gsub("'".freeze, "''".freeze) # ' (for ruby-mode)
       end
 
       # Quotes the column name. Defaults to no quoting.
@@ -68,6 +102,11 @@ module ActiveRecord
         quote_table_name("#{table}.#{attr}")
       end
 
+      def quote_default_expression(value, column) #:nodoc:
+        value = lookup_cast_type(column.sql_type).serialize(value)
+        quote(value)
+      end
+
       def quoted_true
         "'t'"
       end
@@ -84,6 +123,8 @@ module ActiveRecord
         'f'
       end
 
+      # Quote date/time values for use in SQL input. Includes microseconds
+      # if the value is a Time responding to usec.
       def quoted_date(value)
         if value.acts_like?(:time)
           zone_conversion_method = ActiveRecord::Base.default_timezone == :utc ? :getutc : :getlocal
@@ -93,17 +134,16 @@ module ActiveRecord
           end
         end
 
-        value.to_s(:db)
+        result = value.to_s(:db)
+        if value.respond_to?(:usec) && value.usec > 0
+          "#{result}.#{sprintf("%06d", value.usec)}"
+        else
+          result
+        end
       end
 
       def prepare_binds_for_database(binds) # :nodoc:
-        binds.map do |column, value|
-          if column
-            column_name = column.name
-            value = column.cast_type.type_cast_for_database(value)
-          end
-          [column_name, value]
-        end
+        binds.map(&:value_for_database)
       end
 
       private
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
index db20b60d60..0ba4d94e3c 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
@@ -14,38 +14,58 @@ module ActiveRecord
           send m, o
         end
 
-        def visit_AddColumn(o)
-          "ADD #{accept(o)}"
-        end
+        delegate :quote_column_name, :quote_table_name, :quote_default_expression, :type_to_sql,
+          :options_include_default?, :supports_indexes_in_create?, :supports_foreign_keys?, :foreign_key_options, to: :@conn
+        private :quote_column_name, :quote_table_name, :quote_default_expression, :type_to_sql,
+          :options_include_default?, :supports_indexes_in_create?, :supports_foreign_keys?, :foreign_key_options
 
         private
 
           def visit_AlterTable(o)
             sql = "ALTER TABLE #{quote_table_name(o.name)} "
-            sql << o.adds.map { |col| visit_AddColumn col }.join(' ')
+            sql << o.adds.map { |col| accept col }.join(' ')
             sql << o.foreign_key_adds.map { |fk| visit_AddForeignKey fk }.join(' ')
             sql << o.foreign_key_drops.map { |fk| visit_DropForeignKey fk }.join(' ')
           end
 
           def visit_ColumnDefinition(o)
-            o.sql_type = type_to_sql(o.type, o.limit, o.precision, o.scale)
+            o.sql_type ||= type_to_sql(o.type, o.limit, o.precision, o.scale)
             column_sql = "#{quote_column_name(o.name)} #{o.sql_type}"
             add_column_options!(column_sql, column_options(o)) unless o.type == :primary_key
             column_sql
           end
 
+          def visit_AddColumnDefinition(o)
+            "ADD #{accept(o.column)}"
+          end
+
           def visit_TableDefinition(o)
-            create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE "
-            create_sql << "#{quote_table_name(o.name)} "
-            create_sql << "(#{o.columns.map { |c| accept c }.join(', ')}) " unless o.as
+            create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE #{quote_table_name(o.name)} "
+
+            statements = o.columns.map { |c| accept c }
+            statements << accept(o.primary_keys) if o.primary_keys
+
+            if supports_indexes_in_create?
+              statements.concat(o.indexes.map { |column_name, options| index_in_create(o.name, column_name, options) })
+            end
+
+            if supports_foreign_keys?
+              statements.concat(o.foreign_keys.map { |to_table, options| foreign_key_in_create(o.name, to_table, options) })
+            end
+
+            create_sql << "(#{statements.join(', ')}) " if statements.present?
             create_sql << "#{o.options}"
             create_sql << " AS #{@conn.to_sql(o.as)}" if o.as
             create_sql
           end
 
-          def visit_AddForeignKey(o)
+          def visit_PrimaryKeyDefinition(o)
+            "PRIMARY KEY (#{o.name.join(', ')})"
+          end
+
+          def visit_ForeignKeyDefinition(o)
             sql = <<-SQL.strip_heredoc
-              ADD CONSTRAINT #{quote_column_name(o.name)}
+              CONSTRAINT #{quote_column_name(o.name)}
               FOREIGN KEY (#{quote_column_name(o.column)})
                 REFERENCES #{quote_table_name(o.to_table)} (#{quote_column_name(o.primary_key)})
             SQL
@@ -54,6 +74,10 @@ module ActiveRecord
             sql
           end
 
+          def visit_AddForeignKey(o)
+            "ADD #{accept(o)}"
+          end
+
           def visit_DropForeignKey(name)
             "DROP CONSTRAINT #{quote_column_name(name)}"
           end
@@ -67,21 +91,10 @@ module ActiveRecord
             column_options[:after] = o.after
             column_options[:auto_increment] = o.auto_increment
             column_options[:primary_key] = o.primary_key
+            column_options[:collation] = o.collation
             column_options
           end
 
-          def quote_column_name(name)
-            @conn.quote_column_name name
-          end
-
-          def quote_table_name(name)
-            @conn.quote_table_name name
-          end
-
-          def type_to_sql(type, limit, precision, scale)
-            @conn.type_to_sql type.to_sym, limit, precision, scale
-          end
-
           def add_column_options!(sql, options)
             sql << " DEFAULT #{quote_default_expression(options[:default], options[:column])}" if options_include_default?(options)
             # must explicitly check for :null to allow change_column to work on migrations
@@ -97,13 +110,9 @@ module ActiveRecord
             sql
           end
 
-          def quote_default_expression(value, column)
-            value = type_for_column(column).type_cast_for_database(value)
-            @conn.quote(value)
-          end
-
-          def options_include_default?(options)
-            options.include?(:default) && !(options[:null] == false && options[:default].nil?)
+          def foreign_key_in_create(from_table, to_table, options)
+            options = foreign_key_options(from_table, to_table, options)
+            accept ForeignKeyDefinition.new(from_table, to_table, options)
           end
 
           def action_sql(action, dependency)
@@ -118,10 +127,6 @@ module ActiveRecord
               MSG
             end
           end
-
-          def type_for_column(column)
-            @conn.lookup_cast_type(column.sql_type)
-          end
       end
     end
   end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index 7eaa89c9a7..e2ef56798b 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -1,8 +1,3 @@
-require 'date'
-require 'set'
-require 'bigdecimal'
-require 'bigdecimal/util'
-
 module ActiveRecord
   module ConnectionAdapters #:nodoc:
     # Abstract representation of an index definition on a table. Instances of
@@ -15,16 +10,22 @@ module ActiveRecord
     # are typically created by methods in TableDefinition, and added to the
     # +columns+ attribute of said TableDefinition object, in order to be used
     # for generating a number of table creation or table changing SQL statements.
-    class ColumnDefinition < Struct.new(:name, :type, :limit, :precision, :scale, :default, :null, :first, :after, :auto_increment, :primary_key, :sql_type, :cast_type) #:nodoc:
+    class ColumnDefinition < Struct.new(:name, :type, :limit, :precision, :scale, :default, :null, :first, :after, :auto_increment, :primary_key, :collation, :sql_type) #:nodoc:
 
       def primary_key?
         primary_key || type.to_sym == :primary_key
       end
     end
 
+    class AddColumnDefinition < Struct.new(:column) # :nodoc:
+    end
+
     class ChangeColumnDefinition < Struct.new(:column, :name) #:nodoc:
     end
 
+    class PrimaryKeyDefinition < Struct.new(:name) # :nodoc:
+    end
+
     class ForeignKeyDefinition < Struct.new(:from_table, :to_table, :options) #:nodoc:
       def name
         options[:name]
@@ -50,6 +51,14 @@ module ActiveRecord
         options[:primary_key] != default_primary_key
       end
 
+      def defined_for?(options_or_to_table = {})
+        if options_or_to_table.is_a?(Hash)
+          options_or_to_table.all? {|key, value| options[key].to_s == value.to_s }
+        else
+          to_table == options_or_to_table.to_s
+        end
+      end
+
       private
       def default_primary_key
         "id"
@@ -114,30 +123,71 @@ module ActiveRecord
       end
 
       def foreign_key_options
-        as_options(foreign_key)
+        as_options(foreign_key).merge(column: column_name)
       end
 
       def columns
-        result = [["#{name}_id", type, options]]
+        result = [[column_name, type, options]]
         if polymorphic
           result.unshift(["#{name}_type", :string, polymorphic_options])
         end
         result
       end
 
+      def column_name
+        "#{name}_id"
+      end
+
       def column_names
         columns.map(&:first)
       end
 
       def foreign_table_name
-        name.to_s.pluralize
+        foreign_key_options.fetch(:to_table) do
+          Base.pluralize_table_names ? name.to_s.pluralize : name
+        end
+      end
+    end
+
+    module ColumnMethods
+      # Appends a primary key definition to the table definition.
+      # Can be called multiple times, but this is probably not a good idea.
+      def primary_key(name, type = :primary_key, **options)
+        column(name, type, options.merge(primary_key: true))
+      end
+
+      # Appends a column or columns of a specified type.
+      #
+      #  t.string(:goat)
+      #  t.string(:goat, :sheep)
+      #
+      # See TableDefinition#column
+      [
+        :bigint,
+        :binary,
+        :boolean,
+        :date,
+        :datetime,
+        :decimal,
+        :float,
+        :integer,
+        :string,
+        :text,
+        :time,
+        :timestamp,
+      ].each do |column_type|
+        module_eval <<-CODE, __FILE__, __LINE__ + 1
+          def #{column_type}(*args, **options)
+            args.each { |name| column(name, :#{column_type}, options) }
+          end
+        CODE
       end
     end
 
     # Represents the schema of an SQL table in an abstract way. This class
     # provides methods for manipulating the schema representation.
     #
-    # Inside migration files, the +t+ object in +create_table+
+    # Inside migration files, the +t+ object in {create_table}[rdoc-ref:SchemaStatements#create_table]
     # is actually of this type:
     #
     #   class SomeMigration < ActiveRecord::Migration
@@ -153,17 +203,20 @@ module ActiveRecord
     #   end
     #
     # The table definitions
-    # The Columns are stored as a ColumnDefinition in the +columns+ attribute.
+    # The Columns are stored as a ColumnDefinition in the #columns attribute.
     class TableDefinition
+      include ColumnMethods
+
       # An array of ColumnDefinition objects, representing the column changes
       # that have been defined.
       attr_accessor :indexes
-      attr_reader :name, :temporary, :options, :as, :foreign_keys
+      attr_reader :name, :temporary, :options, :as, :foreign_keys, :native
 
       def initialize(types, name, temporary, options, as = nil)
         @columns_hash = {}
         @indexes = {}
         @foreign_keys = {}
+        @primary_keys = nil
         @native = types
         @temporary = temporary
         @options = options
@@ -171,104 +224,37 @@ module ActiveRecord
         @name = name
       end
 
-      def columns; @columns_hash.values; end
-
-      # Appends a primary key definition to the table definition.
-      # Can be called multiple times, but this is probably not a good idea.
-      def primary_key(name, type = :primary_key, options = {})
-        column(name, type, options.merge(:primary_key => true))
+      def primary_keys(name = nil) # :nodoc:
+        @primary_keys = PrimaryKeyDefinition.new(name) if name
+        @primary_keys
       end
 
+      # Returns an array of ColumnDefinition objects for the columns of the table.
+      def columns; @columns_hash.values; end
+
       # Returns a ColumnDefinition for the column with name +name+.
       def [](name)
         @columns_hash[name.to_s]
       end
 
       # Instantiates a new column for the table.
-      # The +type+ parameter is normally one of the migrations native types,
-      # which is one of the following:
-      # <tt>:primary_key</tt>, <tt>:string</tt>, <tt>:text</tt>,
-      # <tt>:integer</tt>, <tt>:float</tt>, <tt>:decimal</tt>,
-      # <tt>:datetime</tt>, <tt>:time</tt>, <tt>:date</tt>,
-      # <tt>:binary</tt>, <tt>:boolean</tt>.
-      #
-      # You may use a type not in this list as long as it is supported by your
-      # database (for example, "polygon" in MySQL), but this will not be database
-      # agnostic and should usually be avoided.
-      #
-      # Available options are (none of these exists by default):
-      # * <tt>:limit</tt> -
-      #   Requests a maximum column length. This is number of characters for <tt>:string</tt> and
-      #   <tt>:text</tt> columns and number of bytes for <tt>:binary</tt> and <tt>:integer</tt> columns.
-      # * <tt>:default</tt> -
-      #   The column's default value. Use nil for NULL.
-      # * <tt>:null</tt> -
-      #   Allows or disallows +NULL+ values in the column. This option could
-      #   have been named <tt>:null_allowed</tt>.
-      # * <tt>:precision</tt> -
-      #   Specifies the precision for a <tt>:decimal</tt> column.
-      # * <tt>:scale</tt> -
-      #   Specifies the scale for a <tt>:decimal</tt> column.
+      # See {connection.add_column}[rdoc-ref:ConnectionAdapters::SchemaStatements#add_column]
+      # for available options.
+      #
+      # Additional options are:
       # * <tt>:index</tt> -
       #   Create an index for the column. Can be either <tt>true</tt> or an options hash.
       #
-      # Note: The precision is the total number of significant digits
-      # and the scale is the number of digits that can be stored following
-      # the decimal point. For example, the number 123.45 has a precision of 5
-      # and a scale of 2. A decimal with a precision of 5 and a scale of 2 can
-      # range from -999.99 to 999.99.
-      #
-      # Please be aware of different RDBMS implementations behavior with
-      # <tt>:decimal</tt> columns:
-      # * The SQL standard says the default scale should be 0, <tt>:scale</tt> <=
-      #   <tt>:precision</tt>, and makes no comments about the requirements of
-      #   <tt>:precision</tt>.
-      # * MySQL: <tt>:precision</tt> [1..63], <tt>:scale</tt> [0..30].
-      #   Default is (10,0).
-      # * PostgreSQL: <tt>:precision</tt> [1..infinity],
-      #   <tt>:scale</tt> [0..infinity]. No default.
-      # * SQLite2: Any <tt>:precision</tt> and <tt>:scale</tt> may be used.
-      #   Internal storage as strings. No default.
-      # * SQLite3: No restrictions on <tt>:precision</tt> and <tt>:scale</tt>,
-      #   but the maximum supported <tt>:precision</tt> is 16. No default.
-      # * Oracle: <tt>:precision</tt> [1..38], <tt>:scale</tt> [-84..127].
-      #   Default is (38,0).
-      # * DB2: <tt>:precision</tt> [1..63], <tt>:scale</tt> [0..62].
-      #   Default unknown.
-      # * SqlServer?: <tt>:precision</tt> [1..38], <tt>:scale</tt> [0..38].
-      #   Default (38,0).
-      #
       # This method returns <tt>self</tt>.
       #
       # == Examples
-      #  # Assuming +td+ is an instance of TableDefinition
-      #  td.column(:granted, :boolean)
-      #  # granted BOOLEAN
-      #
-      #  td.column(:picture, :binary, limit: 2.megabytes)
-      #  # => picture BLOB(2097152)
-      #
-      #  td.column(:sales_stage, :string, limit: 20, default: 'new', null: false)
-      #  # => sales_stage VARCHAR(20) DEFAULT 'new' NOT NULL
-      #
-      #  td.column(:bill_gates_money, :decimal, precision: 15, scale: 2)
-      #  # => bill_gates_money DECIMAL(15,2)
-      #
-      #  td.column(:sensor_reading, :decimal, precision: 30, scale: 20)
-      #  # => sensor_reading DECIMAL(30,20)
       #
-      #  # While <tt>:scale</tt> defaults to zero on most databases, it
-      #  # probably wouldn't hurt to include it.
-      #  td.column(:huge_integer, :decimal, precision: 30)
-      #  # => huge_integer DECIMAL(30)
-      #
-      #  # Defines a column with a database-specific type.
-      #  td.column(:foo, 'polygon')
-      #  # => foo polygon
+      #  # Assuming +td+ is an instance of TableDefinition
+      #  td.column(:granted, :boolean, index: true)
       #
       # == Short-hand examples
       #
-      # Instead of calling +column+ directly, you can also work with the short-hand definitions for the default types.
+      # Instead of calling #column directly, you can also work with the short-hand definitions for the default types.
       # They use the type as the method name instead of as a parameter and allow for multiple columns to be defined
       # in a single statement.
       #
@@ -300,7 +286,8 @@ module ActiveRecord
       # TableDefinition#references will add an appropriately-named _id column, plus a corresponding _type
       # column if the <tt>:polymorphic</tt> option is supplied. If <tt>:polymorphic</tt> is a hash of
       # options, these will be used when creating the <tt>_type</tt> column. The <tt>:index</tt> option
-      # will also create an index, similar to calling <tt>add_index</tt>. So what can be written like this:
+      # will also create an index, similar to calling {add_index}[rdoc-ref:ConnectionAdapters::SchemaStatements#add_index].
+      # So what can be written like this:
       #
       #   create_table :taggings do |t|
       #     t.integer :tag_id, :tagger_id, :taggable_id
@@ -320,6 +307,7 @@ module ActiveRecord
       def column(name, type, options = {})
         name = name.to_s
         type = type.to_sym
+        options = options.dup
 
         if @columns_hash[name] && @columns_hash[name].primary_key?
           raise ArgumentError, "you can't redefine the primary key column '#{name}'. To define a custom primary key, pass { id: false } to create_table."
@@ -331,18 +319,12 @@ module ActiveRecord
         self
       end
 
+      # remove the column +name+ from the table.
+      #   remove_column(:account_id)
       def remove_column(name)
         @columns_hash.delete name.to_s
       end
 
-      [:string, :text, :integer, :bigint, :float, :decimal, :datetime, :timestamp, :time, :date, :binary, :boolean].each do |column_type|
-        define_method column_type do |*args|
-          options = args.extract_options!
-          column_names = args
-          column_names.each { |name| column(name, column_type, options) }
-        end
-      end
-
       # Adds index options to the indexes hash, keyed by column name
       # This is primarily used to track indexes that need to be created after the table
       #
@@ -356,7 +338,7 @@ module ActiveRecord
       end
 
       # Appends <tt>:datetime</tt> columns <tt>:created_at</tt> and
-      # <tt>:updated_at</tt> to the table. See SchemaStatements#add_timestamps
+      # <tt>:updated_at</tt> to the table. See {connection.add_timestamps}[rdoc-ref:SchemaStatements#add_timestamps]
       #
       #   t.timestamps null: false
       def timestamps(*args)
@@ -368,17 +350,12 @@ module ActiveRecord
         column(:updated_at, :datetime, options)
       end
 
-      # Adds a reference. Optionally adds a +type+ column, if the
-      # +:polymorphic+ option is provided. +references+ and +belongs_to+
-      # are acceptable. The reference column will be an +integer+ by default,
-      # the +:type+ option can be used to specify a different type. A foreign
-      # key will be created if the +:foreign_key+ option is passed.
+      # Adds a reference.
       #
       #  t.references(:user)
-      #  t.references(:user, type: "string")
-      #  t.belongs_to(:supplier, polymorphic: true)
+      #  t.belongs_to(:supplier, foreign_key: true)
       #
-      # See SchemaStatements#add_reference
+      # See {connection.add_reference}[rdoc-ref:SchemaStatements#add_reference] for details of the options you can use.
       def references(*args, **options)
         args.each do |col|
           ReferenceDefinition.new(col, **options).add_to(self)
@@ -402,6 +379,7 @@ module ActiveRecord
         column.after       = options[:after]
         column.auto_increment = options[:auto_increment]
         column.primary_key = type == :primary_key || options[:primary_key]
+        column.collation   = options[:collation]
         column
       end
 
@@ -410,10 +388,6 @@ module ActiveRecord
         ColumnDefinition.new name, type
       end
 
-      def native
-        @native
-      end
-
       def aliased_types(name, fallback)
         'timestamp' == name ? :datetime : fallback
       end
@@ -444,16 +418,17 @@ module ActiveRecord
       def add_column(name, type, options)
         name = name.to_s
         type = type.to_sym
-        @adds << @td.new_column_definition(name, type, options)
+        @adds << AddColumnDefinition.new(@td.new_column_definition(name, type, options))
       end
     end
 
     # Represents an SQL table in an abstract way for updating a table.
-    # Also see TableDefinition and SchemaStatements#create_table
+    # Also see TableDefinition and {connection.create_table}[rdoc-ref:SchemaStatements#create_table]
     #
     # Available transformations are:
     #
     #   change_table :table do |t|
+    #     t.primary_key
     #     t.column
     #     t.index
     #     t.rename_index
@@ -466,6 +441,7 @@ module ActiveRecord
     #     t.string
     #     t.text
     #     t.integer
+    #     t.bigint
     #     t.float
     #     t.decimal
     #     t.datetime
@@ -482,6 +458,8 @@ module ActiveRecord
     #   end
     #
     class Table
+      include ColumnMethods
+
       attr_reader :name
 
       def initialize(table_name, base)
@@ -500,7 +478,9 @@ module ActiveRecord
 
       # Checks to see if a column exists.
       #
-      # See SchemaStatements#column_exists?
+      # t.string(:name) unless t.column_exists?(:name, :string)
+      #
+      # See {connection.column_exists?}[rdoc-ref:SchemaStatements#column_exists?]
       def column_exists?(column_name, type = nil, options = {})
         @base.column_exists?(name, column_name, type, options)
       end
@@ -512,14 +492,18 @@ module ActiveRecord
       #  t.index([:branch_id, :party_id], unique: true)
       #  t.index([:branch_id, :party_id], unique: true, name: 'by_branch_party')
       #
-      # See SchemaStatements#add_index for details of the options you can use.
+      # See {connection.add_index}[rdoc-ref:SchemaStatements#add_index] for details of the options you can use.
       def index(column_name, options = {})
         @base.add_index(name, column_name, options)
       end
 
       # Checks to see if an index exists.
       #
-      # See SchemaStatements#index_exists?
+      # unless t.index_exists?(:branch_id)
+      #   t.index(:branch_id)
+      # end
+      #
+      # See {connection.index_exists?}[rdoc-ref:SchemaStatements#index_exists?]
       def index_exists?(column_name, options = {})
         @base.index_exists?(name, column_name, options)
       end
@@ -528,7 +512,7 @@ module ActiveRecord
       #
       #  t.rename_index(:user_id, :account_id)
       #
-      # See SchemaStatements#rename_index
+      # See {connection.rename_index}[rdoc-ref:SchemaStatements#rename_index]
       def rename_index(index_name, new_index_name)
         @base.rename_index(name, index_name, new_index_name)
       end
@@ -537,7 +521,7 @@ module ActiveRecord
       #
       #  t.timestamps(null: false)
       #
-      # See SchemaStatements#add_timestamps
+      # See {connection.add_timestamps}[rdoc-ref:SchemaStatements#add_timestamps]
       def timestamps(options = {})
         @base.add_timestamps(name, options)
       end
@@ -556,10 +540,11 @@ module ActiveRecord
       #
       #  t.change_default(:qualification, 'new')
       #  t.change_default(:authorized, 1)
+      #  t.change_default(:status, from: nil, to: "draft")
       #
-      # See SchemaStatements#change_column_default
-      def change_default(column_name, default)
-        @base.change_column_default(name, column_name, default)
+      # See {connection.change_column_default}[rdoc-ref:SchemaStatements#change_column_default]
+      def change_default(column_name, default_or_changes)
+        @base.change_column_default(name, column_name, default_or_changes)
       end
 
       # Removes the column(s) from the table definition.
@@ -567,7 +552,7 @@ module ActiveRecord
       #  t.remove(:qualification)
       #  t.remove(:qualification, :experience)
       #
-      # See SchemaStatements#remove_columns
+      # See {connection.remove_columns}[rdoc-ref:SchemaStatements#remove_columns]
       def remove(*column_names)
         @base.remove_columns(name, *column_names)
       end
@@ -578,7 +563,7 @@ module ActiveRecord
       #   t.remove_index(column: [:branch_id, :party_id])
       #   t.remove_index(name: :by_branch_party)
       #
-      # See SchemaStatements#remove_index
+      # See {connection.remove_index}[rdoc-ref:SchemaStatements#remove_index]
       def remove_index(options = {})
         @base.remove_index(name, options)
       end
@@ -587,7 +572,7 @@ module ActiveRecord
       #
       #  t.remove_timestamps
       #
-      # See SchemaStatements#remove_timestamps
+      # See {connection.remove_timestamps}[rdoc-ref:SchemaStatements#remove_timestamps]
       def remove_timestamps(options = {})
         @base.remove_timestamps(name, options)
       end
@@ -596,20 +581,17 @@ module ActiveRecord
       #
       #  t.rename(:description, :name)
       #
-      # See SchemaStatements#rename_column
+      # See {connection.rename_column}[rdoc-ref:SchemaStatements#rename_column]
       def rename(column_name, new_column_name)
         @base.rename_column(name, column_name, new_column_name)
       end
 
-      # Adds a reference. Optionally adds a +type+ column, if
-      # <tt>:polymorphic</tt> option is provided.
+      # Adds a reference.
       #
       #  t.references(:user)
-      #  t.references(:user, type: "string")
-      #  t.belongs_to(:supplier, polymorphic: true)
       #  t.belongs_to(:supplier, foreign_key: true)
       #
-      # See SchemaStatements#add_reference
+      # See {connection.add_reference}[rdoc-ref:SchemaStatements#add_reference] for details of the options you can use.
       def references(*args)
         options = args.extract_options!
         args.each do |ref_name|
@@ -623,7 +605,7 @@ module ActiveRecord
       #  t.remove_references(:user)
       #  t.remove_belongs_to(:supplier, polymorphic: true)
       #
-      # See SchemaStatements#remove_reference
+      # See {connection.remove_reference}[rdoc-ref:SchemaStatements#remove_reference]
       def remove_references(*args)
         options = args.extract_options!
         args.each do |ref_name|
@@ -632,25 +614,24 @@ module ActiveRecord
       end
       alias :remove_belongs_to :remove_references
 
-      # Adds a column or columns of a specified type.
+      # Adds a foreign key.
       #
-      #  t.string(:goat)
-      #  t.string(:goat, :sheep)
+      # t.foreign_key(:authors)
       #
-      # See SchemaStatements#add_column
-      [:string, :text, :integer, :float, :decimal, :datetime, :timestamp, :time, :date, :binary, :boolean].each do |column_type|
-        define_method column_type do |*args|
-          options = args.extract_options!
-          args.each do |column_name|
-            @base.add_column(name, column_name, column_type, options)
-          end
-        end
-      end
-
+      # See {connection.add_foreign_key}[rdoc-ref:SchemaStatements#add_foreign_key]
       def foreign_key(*args) # :nodoc:
         @base.add_foreign_key(name, *args)
       end
 
+      # Checks to see if a foreign key exists.
+      #
+      # t.foreign_key(:authors) unless t.foreign_key_exists?(:authors)
+      #
+      # See {connection.foreign_key_exists?}[rdoc-ref:SchemaStatements#foreign_key_exists?]
+      def foreign_key_exists?(*args) # :nodoc:
+        @base.foreign_key_exists?(name, *args)
+      end
+
       private
         def native
           @base.native_database_types
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb
index 42ea599a74..e252ddb4cf 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb
@@ -18,39 +18,72 @@ module ActiveRecord
         spec.merge!(prepare_column_options(column).delete_if { |key, _| [:name, :type].include?(key) })
       end
 
-      # This can be overridden on a Adapter level basis to support other
+      # This can be overridden on an Adapter level basis to support other
       # extended datatypes (Example: Adding an array option in the
-      # PostgreSQLAdapter)
+      # PostgreSQL::ColumnDumper)
       def prepare_column_options(column)
         spec = {}
         spec[:name]      = column.name.inspect
-        spec[:type]      = column.type.to_s
+        spec[:type]      = schema_type(column)
         spec[:null]      = 'false' unless column.null
 
-        limit = column.limit || native_database_types[column.type][:limit]
-        spec[:limit]     = limit.inspect if limit
-        spec[:precision] = column.precision.inspect if column.precision
-        spec[:scale]     = column.scale.inspect if column.scale
+        if limit = schema_limit(column)
+          spec[:limit] = limit
+        end
+
+        if precision = schema_precision(column)
+          spec[:precision] = precision
+        end
+
+        if scale = schema_scale(column)
+          spec[:scale] = scale
+        end
 
         default = schema_default(column) if column.has_default?
         spec[:default]   = default unless default.nil?
 
+        if collation = schema_collation(column)
+          spec[:collation] = collation
+        end
+
         spec
       end
 
       # Lists the valid migration options
       def migration_keys
-        [:name, :limit, :precision, :scale, :default, :null]
+        [:name, :limit, :precision, :scale, :default, :null, :collation]
       end
 
       private
 
+      def schema_type(column)
+        column.type.to_s
+      end
+
+      def schema_limit(column)
+        limit = column.limit || native_database_types[column.type][:limit]
+        limit.inspect if limit
+      end
+
+      def schema_precision(column)
+        column.precision.inspect if column.precision
+      end
+
+      def schema_scale(column)
+        column.scale.inspect if column.scale
+      end
+
       def schema_default(column)
-        default = column.type_cast_from_database(column.default)
+        type = lookup_cast_type_from_column(column)
+        default = type.deserialize(column.default)
         unless default.nil?
-          column.type_cast_for_schema(default)
+          type.type_cast_for_schema(default)
         end
       end
+
+      def schema_collation(column)
+        column.collation.inspect if column.collation
+      end
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 0f44c332ae..d5f8dbc8fc 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -1,4 +1,6 @@
 require 'active_record/migration/join_table'
+require 'active_support/core_ext/string/access'
+require 'digest'
 
 module ActiveRecord
   module ConnectionAdapters # :nodoc:
@@ -12,11 +14,34 @@ module ActiveRecord
         {}
       end
 
+      def table_options(table_name)
+        nil
+      end
+
       # Truncates a table alias according to the limits of the current adapter.
       def table_alias_for(table_name)
         table_name[0...table_alias_length].tr('.', '_')
       end
 
+      # Returns the relation names useable to back Active Record models.
+      # For most adapters this means all #tables and #views.
+      def data_sources
+        tables | views
+      end
+
+      # Checks to see if the data source +name+ exists on the database.
+      #
+      #   data_source_exists?(:ebooks)
+      #
+      def data_source_exists?(name)
+        data_sources.include?(name.to_s)
+      end
+
+      # Returns an array of table names defined in the database.
+      def tables(name = nil)
+        raise NotImplementedError, "#tables is not implemented"
+      end
+
       # Checks to see if the table +table_name+ exists on the database.
       #
       #   table_exists?(:developers)
@@ -25,6 +50,19 @@ module ActiveRecord
         tables.include?(table_name.to_s)
       end
 
+      # Returns an array of view names defined in the database.
+      def views
+        raise NotImplementedError, "#views is not implemented"
+      end
+
+      # Checks to see if the view +view_name+ exists on the database.
+      #
+      #   view_exists?(:ebooks)
+      #
+      def view_exists?(view_name)
+        views.include?(view_name.to_s)
+      end
+
       # Returns an array of indexes for the given table.
       # def indexes(table_name, name = nil) end
 
@@ -82,10 +120,16 @@ module ActiveRecord
                                       (!options.key?(:null)      || c.null == options[:null]) }
       end
 
+      # Returns just a table's primary key
+      def primary_key(table_name)
+        pks = primary_keys(table_name)
+        pks.first if pks.one?
+      end
+
       # Creates a new table with the name +table_name+. +table_name+ may either
       # be a String or a Symbol.
       #
-      # There are two ways to work with +create_table+. You can use the block
+      # There are two ways to work with #create_table. You can use the block
       # form or the regular form, like this:
       #
       # === Block form
@@ -117,13 +161,16 @@ module ActiveRecord
       # The +options+ hash can include the following keys:
       # [<tt>:id</tt>]
       #   Whether to automatically add a primary key column. Defaults to true.
-      #   Join tables for +has_and_belongs_to_many+ should set it to false.
+      #   Join tables for {ActiveRecord::Base.has_and_belongs_to_many}[rdoc-ref:Associations::ClassMethods#has_and_belongs_to_many] should set it to false.
+      #
+      #   A Symbol can be used to specify the type of the generated primary key column.
       # [<tt>:primary_key</tt>]
       #   The name of the primary key, if one is to be added automatically.
       #   Defaults to +id+. If <tt>:id</tt> is false this option is ignored.
       #
       #   Note that Active Record models will automatically detect their
-      #   primary key. This can be avoided by using +self.primary_key=+ on the model
+      #   primary key. This can be avoided by using
+      #   {self.primary_key=}[rdoc-ref:AttributeMethods::PrimaryKey::ClassMethods#primary_key=] on the model
       #   to define the key explicitly.
       #
       # [<tt>:options</tt>]
@@ -145,7 +192,7 @@ module ActiveRecord
       # generates:
       #
       #   CREATE TABLE suppliers (
-      #     id int(11) DEFAULT NULL auto_increment PRIMARY KEY
+      #     id int auto_increment PRIMARY KEY
       #   ) ENGINE=InnoDB DEFAULT CHARSET=utf8
       #
       # ====== Rename the primary key column
@@ -157,10 +204,23 @@ module ActiveRecord
       # generates:
       #
       #   CREATE TABLE objects (
-      #     guid int(11) DEFAULT NULL auto_increment PRIMARY KEY,
+      #     guid int auto_increment PRIMARY KEY,
       #     name varchar(80)
       #   )
       #
+      # ====== Change the primary key column type
+      #
+      #   create_table(:tags, id: :string) do |t|
+      #     t.column :label, :string
+      #   end
+      #
+      # generates:
+      #
+      #   CREATE TABLE tags (
+      #     id varchar PRIMARY KEY,
+      #     label varchar
+      #   )
+      #
       # ====== Do not add a primary key column
       #
       #   create_table(:categories_suppliers, id: false) do |t|
@@ -194,7 +254,11 @@ module ActiveRecord
             Base.get_primary_key table_name.to_s.singularize
           end
 
-          td.primary_key pk, options.fetch(:id, :primary_key), options
+          if pk.is_a?(Array)
+            td.primary_keys pk
+          else
+            td.primary_key pk, options.fetch(:id, :primary_key), options
+          end
         end
 
         yield td if block_given?
@@ -211,10 +275,6 @@ module ActiveRecord
           end
         end
 
-        td.foreign_keys.each_pair do |other_table_name, foreign_key_options|
-          add_foreign_key(table_name, other_table_name, foreign_key_options)
-        end
-
         result
       end
 
@@ -237,7 +297,7 @@ module ActiveRecord
       #   Set to true to drop the table before creating it.
       #   Defaults to false.
       #
-      # Note that +create_join_table+ does not create any indices by default; you can use
+      # Note that #create_join_table does not create any indices by default; you can use
       # its block form to do so yourself:
       #
       #   create_join_table :products, :categories do |t|
@@ -272,11 +332,11 @@ module ActiveRecord
       end
 
       # Drops the join table specified by the given arguments.
-      # See +create_join_table+ for details.
+      # See #create_join_table for details.
       #
       # Although this command ignores the block if one is given, it can be helpful
       # to provide one in a migration's +change+ method so it can be reverted.
-      # In that case, the block will be used by create_join_table.
+      # In that case, the block will be used by #create_join_table.
       def drop_join_table(table_1, table_2, options = {})
         join_table_name = find_join_table_name(table_1, table_2, options)
         drop_table(join_table_name)
@@ -294,7 +354,7 @@ module ActiveRecord
       # [<tt>:bulk</tt>]
       #   Set this to true to make this a bulk alter query, such as
       #
-      #     ALTER TABLE `users` ADD COLUMN age INT(11), ADD COLUMN birthdate DATETIME ...
+      #     ALTER TABLE `users` ADD COLUMN age INT, ADD COLUMN birthdate DATETIME ...
       #
       #   Defaults to false.
       #
@@ -375,16 +435,92 @@ module ActiveRecord
       # [<tt>:force</tt>]
       #   Set to +:cascade+ to drop dependent objects as well.
       #   Defaults to false.
+      # [<tt>:if_exists</tt>]
+      #   Set to +true+ to only drop the table if it exists.
+      #   Defaults to false.
       #
       # Although this command ignores most +options+ and the block if one is given,
       # it can be helpful to provide these in a migration's +change+ method so it can be reverted.
-      # In that case, +options+ and the block will be used by create_table.
+      # In that case, +options+ and the block will be used by #create_table.
       def drop_table(table_name, options = {})
-        execute "DROP TABLE #{quote_table_name(table_name)}"
+        execute "DROP TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}"
       end
 
-      # Adds a new column to the named table.
-      # See TableDefinition#column for details of the options you can use.
+      # Add a new +type+ column named +column_name+ to +table_name+.
+      #
+      # The +type+ parameter is normally one of the migrations native types,
+      # which is one of the following:
+      # <tt>:primary_key</tt>, <tt>:string</tt>, <tt>:text</tt>,
+      # <tt>:integer</tt>, <tt>:bigint</tt>, <tt>:float</tt>, <tt>:decimal</tt>,
+      # <tt>:datetime</tt>, <tt>:time</tt>, <tt>:date</tt>,
+      # <tt>:binary</tt>, <tt>:boolean</tt>.
+      #
+      # You may use a type not in this list as long as it is supported by your
+      # database (for example, "polygon" in MySQL), but this will not be database
+      # agnostic and should usually be avoided.
+      #
+      # Available options are (none of these exists by default):
+      # * <tt>:limit</tt> -
+      #   Requests a maximum column length. This is number of characters for a <tt>:string</tt> column
+      #   and number of bytes for <tt>:text</tt>, <tt>:binary</tt> and <tt>:integer</tt> columns.
+      # * <tt>:default</tt> -
+      #   The column's default value. Use nil for NULL.
+      # * <tt>:null</tt> -
+      #   Allows or disallows +NULL+ values in the column. This option could
+      #   have been named <tt>:null_allowed</tt>.
+      # * <tt>:precision</tt> -
+      #   Specifies the precision for a <tt>:decimal</tt> column.
+      # * <tt>:scale</tt> -
+      #   Specifies the scale for a <tt>:decimal</tt> column.
+      #
+      # Note: The precision is the total number of significant digits
+      # and the scale is the number of digits that can be stored following
+      # the decimal point. For example, the number 123.45 has a precision of 5
+      # and a scale of 2. A decimal with a precision of 5 and a scale of 2 can
+      # range from -999.99 to 999.99.
+      #
+      # Please be aware of different RDBMS implementations behavior with
+      # <tt>:decimal</tt> columns:
+      # * The SQL standard says the default scale should be 0, <tt>:scale</tt> <=
+      #   <tt>:precision</tt>, and makes no comments about the requirements of
+      #   <tt>:precision</tt>.
+      # * MySQL: <tt>:precision</tt> [1..63], <tt>:scale</tt> [0..30].
+      #   Default is (10,0).
+      # * PostgreSQL: <tt>:precision</tt> [1..infinity],
+      #   <tt>:scale</tt> [0..infinity]. No default.
+      # * SQLite2: Any <tt>:precision</tt> and <tt>:scale</tt> may be used.
+      #   Internal storage as strings. No default.
+      # * SQLite3: No restrictions on <tt>:precision</tt> and <tt>:scale</tt>,
+      #   but the maximum supported <tt>:precision</tt> is 16. No default.
+      # * Oracle: <tt>:precision</tt> [1..38], <tt>:scale</tt> [-84..127].
+      #   Default is (38,0).
+      # * DB2: <tt>:precision</tt> [1..63], <tt>:scale</tt> [0..62].
+      #   Default unknown.
+      # * SqlServer?: <tt>:precision</tt> [1..38], <tt>:scale</tt> [0..38].
+      #   Default (38,0).
+      #
+      # == Examples
+      #
+      #  add_column(:users, :picture, :binary, limit: 2.megabytes)
+      #  # ALTER TABLE "users" ADD "picture" blob(2097152)
+      #
+      #  add_column(:articles, :status, :string, limit: 20, default: 'draft', null: false)
+      #  # ALTER TABLE "articles" ADD "status" varchar(20) DEFAULT 'draft' NOT NULL
+      #
+      #  add_column(:answers, :bill_gates_money, :decimal, precision: 15, scale: 2)
+      #  # ALTER TABLE "answers" ADD "bill_gates_money" decimal(15,2)
+      #
+      #  add_column(:measurements, :sensor_reading, :decimal, precision: 30, scale: 20)
+      #  # ALTER TABLE "measurements" ADD "sensor_reading" decimal(30,20)
+      #
+      #  # While :scale defaults to zero on most databases, it
+      #  # probably wouldn't hurt to include it.
+      #  add_column(:measurements, :huge_integer, :decimal, precision: 30)
+      #  # ALTER TABLE "measurements" ADD "huge_integer" decimal(30)
+      #
+      #  # Defines a column with a database-specific type.
+      #  add_column(:shapes, :triangle, 'polygon')
+      #  # ALTER TABLE "shapes" ADD "triangle" polygon
       def add_column(table_name, column_name, type, options = {})
         at = create_alter_table table_name
         at.add_column(column_name, type, options)
@@ -432,11 +568,16 @@ module ActiveRecord
       #
       #   change_column_default(:users, :email, nil)
       #
-      def change_column_default(table_name, column_name, default)
+      # Passing a hash containing +:from+ and +:to+ will make this change
+      # reversible in migration:
+      #
+      #   change_column_default(:posts, :state, from: nil, to: "draft")
+      #
+      def change_column_default(table_name, column_name, default_or_changes)
         raise NotImplementedError, "change_column_default is not implemented"
       end
 
-      # Sets or removes a +NOT NULL+ constraint on a column. The +null+ flag
+      # Sets or removes a <tt>NOT NULL</tt> constraint on a column. The +null+ flag
       # indicates whether the value can be +NULL+. For example
       #
       #   change_column_null(:users, :nickname, false)
@@ -448,7 +589,7 @@ module ActiveRecord
       # allows them to be +NULL+ (drops the constraint).
       #
       # The method accepts an optional fourth argument to replace existing
-      # +NULL+s with some other value. Use that one when enabling the
+      # <tt>NULL</tt>s with some other value. Use that one when enabling the
       # constraint if needed, since otherwise those rows would not be valid.
       #
       # Please note the fourth argument does not set a column's default.
@@ -502,6 +643,8 @@ module ActiveRecord
       #
       #   CREATE INDEX by_name ON accounts(name(10))
       #
+      # ====== Creating an index with specific key lengths for multiple keys
+      #
       #   add_index(:accounts, [:name, :surname], name: 'by_name_surname', length: {name: 10, surname: 15})
       #
       # generates:
@@ -528,6 +671,8 @@ module ActiveRecord
       #
       #   CREATE UNIQUE INDEX index_accounts_on_branch_id_and_party_id ON accounts(branch_id, party_id) WHERE active
       #
+      # Note: Partial indexes are only supported for PostgreSQL and SQLite 3.8.0+.
+      #
       # ====== Creating an index with a specific method
       #
       #   add_index(:developers, :name, using: 'btree')
@@ -557,7 +702,7 @@ module ActiveRecord
       #
       # Removes the +index_accounts_on_column+ in the +accounts+ table.
       #
-      #   remove_index :accounts, :column
+      #   remove_index :accounts, :branch_id
       #
       # Removes the index named +index_accounts_on_branch_id+ in the +accounts+ table.
       #
@@ -572,10 +717,7 @@ module ActiveRecord
       #   remove_index :accounts, name: :by_branch_party
       #
       def remove_index(table_name, options = {})
-        remove_index!(table_name, index_name_for_remove(table_name, options))
-      end
-
-      def remove_index!(table_name, index_name) #:nodoc:
+        index_name = index_name_for_remove(table_name, options)
         execute "DROP INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)}"
       end
 
@@ -619,10 +761,22 @@ module ActiveRecord
         indexes(table_name).detect { |i| i.name == index_name }
       end
 
-      # Adds a reference. Optionally adds a +type+ column, if <tt>:polymorphic</tt> option is provided.
-      # The reference column is an +integer+ by default, the <tt>:type</tt> option can be used to specify
-      # a different type.
-      # <tt>add_reference</tt> and <tt>add_belongs_to</tt> are acceptable.
+      # Adds a reference. The reference column is an integer by default,
+      # the <tt>:type</tt> option can be used to specify a different type.
+      # Optionally adds a +_type+ column, if <tt>:polymorphic</tt> option is provided.
+      # #add_reference and #add_belongs_to are acceptable.
+      #
+      # The +options+ hash can include the following keys:
+      # [<tt>:type</tt>]
+      #   The reference column type. Defaults to +:integer+.
+      # [<tt>:index</tt>]
+      #   Add an appropriate index. Defaults to false.
+      # [<tt>:foreign_key</tt>]
+      #   Add an appropriate foreign key constraint. Defaults to false.
+      # [<tt>:polymorphic</tt>]
+      #   Whether an additional +_type+ column should be added. Defaults to false.
+      # [<tt>:null</tt>]
+      #   Whether the column allows nulls. Defaults to true.
       #
       # ====== Create a user_id integer column
       #
@@ -632,10 +786,6 @@ module ActiveRecord
       #
       #   add_reference(:products, :user, type: :string)
       #
-      # ====== Create a supplier_id and supplier_type columns
-      #
-      #   add_belongs_to(:products, :supplier, polymorphic: true)
-      #
       # ====== Create supplier_id, supplier_type columns and appropriate index
       #
       #   add_reference(:products, :supplier, polymorphic: true, index: true)
@@ -644,13 +794,17 @@ module ActiveRecord
       #
       #   add_reference(:products, :supplier, foreign_key: true)
       #
+      # ====== Create a supplier_id column and a foreign key to the firms table
+      #
+      #   add_reference(:products, :supplier, foreign_key: {to_table: :firms})
+      #
       def add_reference(table_name, *args)
         ReferenceDefinition.new(*args).add_to(update_table_definition(table_name, self))
       end
       alias :add_belongs_to :add_reference
 
       # Removes the reference(s). Also removes a +type+ column if one exists.
-      # <tt>remove_reference</tt>, <tt>remove_references</tt> and <tt>remove_belongs_to</tt> are acceptable.
+      # #remove_reference and #remove_belongs_to are acceptable.
       #
       # ====== Remove the reference
       #
@@ -660,14 +814,23 @@ module ActiveRecord
       #
       #   remove_reference(:products, :supplier, polymorphic: true)
       #
+      # ====== Remove the reference with a foreign key
+      #
+      #   remove_reference(:products, :user, index: true, foreign_key: true)
+      #
       def remove_reference(table_name, ref_name, options = {})
+        if options[:foreign_key]
+          reference_name = Base.pluralize_table_names ? ref_name.to_s.pluralize : ref_name
+          remove_foreign_key(table_name, reference_name)
+        end
+
         remove_column(table_name, "#{ref_name}_id")
         remove_column(table_name, "#{ref_name}_type") if options[:polymorphic]
       end
       alias :remove_belongs_to :remove_reference
 
       # Returns an array of foreign keys for the given table.
-      # The foreign keys are represented as +ForeignKeyDefinition+ objects.
+      # The foreign keys are represented as ForeignKeyDefinition objects.
       def foreign_keys(table_name)
         raise NotImplementedError, "foreign_keys is not implemented"
       end
@@ -676,8 +839,8 @@ module ActiveRecord
       # +to_table+ contains the referenced primary key.
       #
       # The foreign key will be named after the following pattern: <tt>fk_rails_<identifier></tt>.
-      # +identifier+ is a 10 character long random string. A custom name can be specified with
-      # the <tt>:name</tt> option.
+      # +identifier+ is a 10 character long string which is deterministically generated from the
+      # +from_table+ and +column+. A custom name can be specified with the <tt>:name</tt> option.
       #
       # ====== Creating a simple foreign key
       #
@@ -711,28 +874,23 @@ module ActiveRecord
       # [<tt>:name</tt>]
       #   The constraint name. Defaults to <tt>fk_rails_<identifier></tt>.
       # [<tt>:on_delete</tt>]
-      #   Action that happens <tt>ON DELETE</tt>. Valid values are +:nullify+, +:cascade:+ and +:restrict+
+      #   Action that happens <tt>ON DELETE</tt>. Valid values are +:nullify+, +:cascade+ and +:restrict+
       # [<tt>:on_update</tt>]
-      #   Action that happens <tt>ON UPDATE</tt>. Valid values are +:nullify+, +:cascade:+ and +:restrict+
+      #   Action that happens <tt>ON UPDATE</tt>. Valid values are +:nullify+, +:cascade+ and +:restrict+
       def add_foreign_key(from_table, to_table, options = {})
         return unless supports_foreign_keys?
 
-        options[:column] ||= foreign_key_column_for(to_table)
-
-        options = {
-          column: options[:column],
-          primary_key: options[:primary_key],
-          name: foreign_key_name(from_table, options),
-          on_delete: options[:on_delete],
-          on_update: options[:on_update]
-        }
+        options = foreign_key_options(from_table, to_table, options)
         at = create_alter_table from_table
         at.add_foreign_key to_table, options
 
         execute schema_creation.accept(at)
       end
 
-      # Removes the given foreign key from the table.
+      # Removes the given foreign key from the table. Any option parameters provided
+      # will be used to re-add the foreign key in case of a migration rollback.
+      # It is recommended that you provide any options used when creating the foreign
+      # key so that the migration can be reverted properly.
       #
       # Removes the foreign key on +accounts.branch_id+.
       #
@@ -746,24 +904,11 @@ module ActiveRecord
       #
       #   remove_foreign_key :accounts, name: :special_fk_name
       #
+      # The +options+ hash accepts the same keys as SchemaStatements#add_foreign_key.
       def remove_foreign_key(from_table, options_or_to_table = {})
         return unless supports_foreign_keys?
 
-        if options_or_to_table.is_a?(Hash)
-          options = options_or_to_table
-        else
-          options = { column: foreign_key_column_for(options_or_to_table) }
-        end
-
-        fk_name_to_delete = options.fetch(:name) do
-          fk_to_delete = foreign_keys(from_table).detect {|fk| fk.column == options[:column].to_s }
-
-          if fk_to_delete
-            fk_to_delete.name
-          else
-            raise ArgumentError, "Table '#{from_table}' has no foreign key on column '#{options[:column]}'"
-          end
-        end
+        fk_name_to_delete = foreign_key_for!(from_table, options_or_to_table).name
 
         at = create_alter_table from_table
         at.drop_foreign_key fk_name_to_delete
@@ -771,8 +916,43 @@ module ActiveRecord
         execute schema_creation.accept(at)
       end
 
+      # Checks to see if a foreign key exists on a table for a given foreign key definition.
+      #
+      #   # Check a foreign key exists
+      #   foreign_key_exists?(:accounts, :branches)
+      #
+      #   # Check a foreign key on a specified column exists
+      #   foreign_key_exists?(:accounts, column: :owner_id)
+      #
+      #   # Check a foreign key with a custom name exists
+      #   foreign_key_exists?(:accounts, name: "special_fk_name")
+      #
+      def foreign_key_exists?(from_table, options_or_to_table = {})
+        foreign_key_for(from_table, options_or_to_table).present?
+      end
+
+      def foreign_key_for(from_table, options_or_to_table = {}) # :nodoc:
+        return unless supports_foreign_keys?
+        foreign_keys(from_table).detect {|fk| fk.defined_for? options_or_to_table }
+      end
+
+      def foreign_key_for!(from_table, options_or_to_table = {}) # :nodoc:
+        foreign_key_for(from_table, options_or_to_table) or \
+          raise ArgumentError, "Table '#{from_table}' has no foreign key for #{options_or_to_table}"
+      end
+
       def foreign_key_column_for(table_name) # :nodoc:
-        "#{table_name.to_s.singularize}_id"
+        prefix = Base.table_name_prefix
+        suffix = Base.table_name_suffix
+        name = table_name.to_s =~ /#{prefix}(.+)#{suffix}/ ? $1 : table_name.to_s
+        "#{name.singularize}_id"
+      end
+
+      def foreign_key_options(from_table, to_table, options) # :nodoc:
+        options = options.dup
+        options[:column] ||= foreign_key_column_for(to_table)
+        options[:name]   ||= foreign_key_name(from_table, options)
+        options
       end
 
       def dump_schema_information #:nodoc:
@@ -789,7 +969,7 @@ module ActiveRecord
         ActiveRecord::SchemaMigration.create_table
       end
 
-      def assume_migrated_upto_version(version, migrations_paths = ActiveRecord::Migrator.migrations_paths)
+      def assume_migrated_upto_version(version, migrations_paths)
         migrations_paths = Array(migrations_paths)
         version = version.to_i
         sm_table = quote_table_name(ActiveRecord::Migrator.schema_migrations_table_name)
@@ -832,6 +1012,12 @@ module ActiveRecord
               raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale is specified"
             end
 
+          elsif [:datetime, :time].include?(type) && precision ||= native[:precision]
+            if (0..6) === precision
+              column_type_sql << "(#{precision})"
+            else
+              raise(ActiveRecordError, "No #{native[:name]} type has precision of #{precision}. The allowed range of precision is from 0 to 6")
+            end
           elsif (type != :primary_key) && (limit ||= native.is_a?(Hash) && native[:limit])
             column_type_sql << "(#{limit})"
           end
@@ -878,13 +1064,13 @@ module ActiveRecord
 
       def add_index_options(table_name, column_name, options = {}) #:nodoc:
         column_names = Array(column_name)
-        index_name   = index_name(table_name, column: column_names)
 
         options.assert_valid_keys(:unique, :order, :name, :where, :length, :internal, :using, :algorithm, :type)
 
-        index_type = options[:unique] ? "UNIQUE" : ""
         index_type = options[:type].to_s if options.key?(:type)
+        index_type ||= options[:unique] ? "UNIQUE" : ""
         index_name = options[:name].to_s if options.key?(:name)
+        index_name ||= index_name(table_name, column: column_names)
         max_index_length = options.fetch(:internal, false) ? index_name_length : allowed_index_name_length
 
         if options.key?(:algorithm)
@@ -910,6 +1096,10 @@ module ActiveRecord
         [index_name, index_type, index_columns, index_options, algorithm, using]
       end
 
+      def options_include_default?(options)
+        options.include?(:default) && !(options[:null] == false && options[:default].nil?)
+      end
+
       protected
         def add_index_sort_order(option_strings, column_names, options = {})
           if options.is_a?(Hash) && order = options[:order]
@@ -936,10 +1126,6 @@ module ActiveRecord
           column_names.map {|name| quote_column_name(name) + option_strings[name]}
         end
 
-        def options_include_default?(options)
-          options.include?(:default) && !(options[:null] == false && options[:default].nil?)
-        end
-
         def index_name_for_remove(table_name, options = {})
           index_name = index_name(table_name, options)
 
@@ -990,16 +1176,26 @@ module ActiveRecord
       end
 
       def foreign_key_name(table_name, options) # :nodoc:
+        identifier = "#{table_name}_#{options.fetch(:column)}_fk"
+        hashed_identifier = Digest::SHA256.hexdigest(identifier).first(10)
         options.fetch(:name) do
-          "fk_rails_#{SecureRandom.hex(5)}"
+          "fk_rails_#{hashed_identifier}"
         end
       end
 
-      def validate_index_length!(table_name, new_name)
+      def validate_index_length!(table_name, new_name) # :nodoc:
         if new_name.length > allowed_index_name_length
           raise ArgumentError, "Index name '#{new_name}' on table '#{table_name}' is too long; the limit is #{allowed_index_name_length} characters"
         end
       end
+
+      def extract_new_default_value(default_or_changes)
+        if default_or_changes.is_a?(Hash) && default_or_changes.has_key?(:from) && default_or_changes.has_key?(:to)
+          default_or_changes[:to]
+        else
+          default_or_changes
+        end
+      end
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
index 7535e9147a..295a7bed87 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
@@ -1,13 +1,10 @@
 module ActiveRecord
   module ConnectionAdapters
     class TransactionState
-      attr_reader :parent
-
       VALID_STATES = Set.new([:committed, :rolledback, nil])
 
       def initialize(state = nil)
         @state = state
-        @parent = nil
       end
 
       def finalized?
@@ -27,7 +24,7 @@ module ActiveRecord
       end
 
       def set_state(state)
-        if !VALID_STATES.include?(state)
+        unless VALID_STATES.include?(state)
           raise ArgumentError, "Invalid transaction state: #{state}"
         end
         @state = state
@@ -47,19 +44,16 @@ module ActiveRecord
       attr_reader :connection, :state, :records, :savepoint_name
       attr_writer :joinable
 
-      def initialize(connection, options)
+      def initialize(connection, options, run_commit_callbacks: false)
         @connection = connection
         @state = TransactionState.new
         @records = []
         @joinable = options.fetch(:joinable, true)
+        @run_commit_callbacks = run_commit_callbacks
       end
 
       def add_record(record)
-        if record.has_transactional_callbacks?
-          records << record
-        else
-          record.set_transaction_state(@state)
-        end
+        records << record
       end
 
       def rollback
@@ -81,15 +75,22 @@ module ActiveRecord
         @state.set_state(:committed)
       end
 
+      def before_commit_records
+        records.uniq.each(&:before_committed!) if @run_commit_callbacks
+      end
+
       def commit_records
         ite = records.uniq
         while record = ite.shift
-          record.committed!
+          if @run_commit_callbacks
+            record.committed!
+          else
+            # if not running callbacks, only adds the record to the parent transaction
+            record.add_to_transaction
+          end
         end
       ensure
-        ite.each do |i|
-          i.committed!(should_run_callbacks: false)
-        end
+        ite.each { |i| i.committed!(should_run_callbacks: false) }
       end
 
       def full_rollback?; true; end
@@ -100,8 +101,8 @@ module ActiveRecord
 
     class SavepointTransaction < Transaction
 
-      def initialize(connection, savepoint_name, options)
-        super(connection, options)
+      def initialize(connection, savepoint_name, options, *args)
+        super(connection, options, *args)
         if options[:isolation]
           raise ActiveRecord::TransactionIsolationError, "cannot set transaction isolation in a nested transaction"
         end
@@ -111,7 +112,6 @@ module ActiveRecord
       def rollback
         connection.rollback_to_savepoint(savepoint_name)
         super
-        rollback_records
       end
 
       def commit
@@ -124,7 +124,7 @@ module ActiveRecord
 
     class RealTransaction < Transaction
 
-      def initialize(connection, options)
+      def initialize(connection, options, *args)
         super
         if options[:isolation]
           connection.begin_isolated_db_transaction(options[:isolation])
@@ -136,13 +136,11 @@ module ActiveRecord
       def rollback
         connection.rollback_db_transaction
         super
-        rollback_records
       end
 
       def commit
         connection.commit_db_transaction
         super
-        commit_records
       end
     end
 
@@ -153,24 +151,31 @@ module ActiveRecord
       end
 
       def begin_transaction(options = {})
+        run_commit_callbacks = !current_transaction.joinable?
         transaction =
           if @stack.empty?
-            RealTransaction.new(@connection, options)
+            RealTransaction.new(@connection, options, run_commit_callbacks: run_commit_callbacks)
           else
-            SavepointTransaction.new(@connection, "active_record_#{@stack.size}", options)
+            SavepointTransaction.new(@connection, "active_record_#{@stack.size}", options,
+                                     run_commit_callbacks: run_commit_callbacks)
           end
+
         @stack.push(transaction)
         transaction
       end
 
       def commit_transaction
-        transaction = @stack.pop
+        transaction = @stack.last
+        transaction.before_commit_records
+        @stack.pop
         transaction.commit
-        transaction.records.each { |r| current_transaction.add_record(r) }
+        transaction.commit_records
       end
 
-      def rollback_transaction
-        @stack.pop.rollback
+      def rollback_transaction(transaction = nil)
+        transaction ||= @stack.pop
+        transaction.rollback
+        transaction.rollback_records
       end
 
       def within_new_transaction(options = {})
@@ -182,12 +187,12 @@ module ActiveRecord
       ensure
         unless error
           if Thread.current.status == 'aborting'
-            rollback_transaction
+            rollback_transaction if transaction
           else
             begin
               commit_transaction
             rescue Exception
-              transaction.rollback unless transaction.state.completed?
+              rollback_transaction(transaction) unless transaction.state.completed?
               raise
             end
           end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index c941c9f1eb..402159ac13 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -1,12 +1,10 @@
-require 'date'
-require 'bigdecimal'
-require 'bigdecimal/util'
 require 'active_record/type'
 require 'active_support/core_ext/benchmark'
+require 'active_record/connection_adapters/determine_if_preparable_visitor'
 require 'active_record/connection_adapters/schema_cache'
+require 'active_record/connection_adapters/sql_type_metadata'
 require 'active_record/connection_adapters/abstract/schema_dumper'
 require 'active_record/connection_adapters/abstract/schema_creation'
-require 'monitor'
 require 'arel/collectors/bind'
 require 'arel/collectors/sql_string'
 
@@ -54,22 +52,21 @@ module ActiveRecord
     # related classes form the abstraction layer which makes this possible.
     # An AbstractAdapter represents a connection to a database, and provides an
     # abstract interface for database-specific functionality such as establishing
-    # a connection, escaping values, building the right SQL fragments for ':offset'
-    # and ':limit' options, etc.
+    # a connection, escaping values, building the right SQL fragments for +:offset+
+    # and +:limit+ options, etc.
     #
     # All the concrete database adapters follow the interface laid down in this class.
-    # ActiveRecord::Base.connection returns an AbstractAdapter object, which
+    # {ActiveRecord::Base.connection}[rdoc-ref:ConnectionHandling#connection] returns an AbstractAdapter object, which
     # you can use.
     #
     # Most of the methods in the adapter are useful during migrations. Most
-    # notably, the instance methods provided by SchemaStatement are very useful.
+    # notably, the instance methods provided by SchemaStatements are very useful.
     class AbstractAdapter
       ADAPTER_NAME = 'Abstract'.freeze
       include Quoting, DatabaseStatements, SchemaStatements
       include DatabaseLimits
       include QueryCache
       include ActiveSupport::Callbacks
-      include MonitorMixin
       include ColumnDumper
 
       SIMPLE_INT = /\A\d+\z/
@@ -111,10 +108,22 @@ module ActiveRecord
         @prepared_statements = false
       end
 
+      class Version
+        include Comparable
+
+        def initialize(version_string)
+          @version = version_string.split('.').map(&:to_i)
+        end
+
+        def <=>(version_string)
+          @version <=> version_string.split('.').map(&:to_i)
+        end
+      end
+
       class BindCollector < Arel::Collectors::Bind
         def compile(bvs, conn)
           casted_binds = conn.prepare_binds_for_database(bvs)
-          super(casted_binds.map { |_, value| conn.quote(value) })
+          super(casted_binds.map { |value| conn.quote(value) })
         end
       end
 
@@ -140,12 +149,20 @@ module ActiveRecord
         SchemaCreation.new self
       end
 
+      # this method must only be called while holding connection pool's mutex
       def lease
-        synchronize do
-          unless in_use?
-            @owner = Thread.current
+        if in_use?
+          msg = 'Cannot lease connection, '
+          if @owner == Thread.current
+            msg << 'it is already leased by the current thread.'
+          else
+            msg << "it is already in use by a different thread: #{@owner}. " <<
+                   "Current thread: #{Thread.current}."
           end
+          raise ActiveRecordError, msg
         end
+
+        @owner = Thread.current
       end
 
       def schema_cache=(cache)
@@ -153,6 +170,7 @@ module ActiveRecord
         @schema_cache = cache
       end
 
+      # this method must only be called while holding connection pool's mutex
       def expire
         @owner = nil
       end
@@ -244,6 +262,16 @@ module ActiveRecord
         false
       end
 
+      # Does this adapter support datetime with precision?
+      def supports_datetime_with_precision?
+        false
+      end
+
+      # Does this adapter support json data type?
+      def supports_json?
+        false
+      end
+
       # This is meant to be implemented by the adapters that support extensions
       def disable_extension(name)
       end
@@ -262,18 +290,6 @@ module ActiveRecord
         {}
       end
 
-      # QUOTING ==================================================
-
-      # Quote date/time values for use in SQL input. Includes microseconds
-      # if the value is a Time responding to usec.
-      def quoted_date(value) #:nodoc:
-        if value.acts_like?(:time) && value.respond_to?(:usec)
-          "#{super}.#{sprintf("%06d", value.usec)}"
-        else
-          super
-        end
-      end
-
       # Returns a bind substitution value given a bind +column+
       # NOTE: The column param is currently being used by the sqlserver-adapter
       def substitute_at(column, _unused = 0)
@@ -333,7 +349,7 @@ module ActiveRecord
       end
 
       # Checks whether the connection to the database is still active (i.e. not stale).
-      # This is done under the hood by calling <tt>active?</tt>. If the connection
+      # This is done under the hood by calling #active?. If the connection
       # is no longer active, then this method will reconnect to the database.
       def verify!(*ignored)
         reconnect! unless active?
@@ -366,9 +382,18 @@ module ActiveRecord
       end
 
       def case_insensitive_comparison(table, attribute, column, value)
-        table[attribute].lower.eq(table.lower(value))
+        if can_perform_case_insensitive_comparison_for?(column)
+          table[attribute].lower.eq(table.lower(value))
+        else
+          case_sensitive_comparison(table, attribute, column, value)
+        end
       end
 
+      def can_perform_case_insensitive_comparison_for?(column)
+        true
+      end
+      private :can_perform_case_insensitive_comparison_for?
+
       def current_savepoint_name
         current_transaction.savepoint_name
       end
@@ -384,8 +409,8 @@ module ActiveRecord
         end
       end
 
-      def new_column(name, default, cast_type, sql_type = nil, null = true)
-        Column.new(name, default, cast_type, sql_type, null)
+      def new_column(name, default, sql_type_metadata = nil, null = true, default_function = nil, collation = nil)
+        Column.new(name, default, sql_type_metadata, null, default_function, collation)
       end
 
       def lookup_cast_type(sql_type) # :nodoc:
@@ -399,15 +424,15 @@ module ActiveRecord
       protected
 
       def initialize_type_map(m) # :nodoc:
-        register_class_with_limit m, %r(boolean)i,   Type::Boolean
-        register_class_with_limit m, %r(char)i,      Type::String
-        register_class_with_limit m, %r(binary)i,    Type::Binary
-        register_class_with_limit m, %r(text)i,      Type::Text
-        register_class_with_limit m, %r(date)i,      Type::Date
-        register_class_with_limit m, %r(time)i,      Type::Time
-        register_class_with_limit m, %r(datetime)i,  Type::DateTime
-        register_class_with_limit m, %r(float)i,     Type::Float
-        register_class_with_limit m, %r(int)i,       Type::Integer
+        register_class_with_limit m, %r(boolean)i,       Type::Boolean
+        register_class_with_limit m, %r(char)i,          Type::String
+        register_class_with_limit m, %r(binary)i,        Type::Binary
+        register_class_with_limit m, %r(text)i,          Type::Text
+        register_class_with_precision m, %r(date)i,      Type::Date
+        register_class_with_precision m, %r(time)i,      Type::Time
+        register_class_with_precision m, %r(datetime)i,  Type::DateTime
+        register_class_with_limit m, %r(float)i,         Type::Float
+        register_class_with_limit m, %r(int)i,           Type::Integer
 
         m.alias_type %r(blob)i,      'binary'
         m.alias_type %r(clob)i,      'text'
@@ -441,6 +466,13 @@ module ActiveRecord
         end
       end
 
+      def register_class_with_precision(mapping, key, klass) # :nodoc:
+        mapping.register_type(key) do |*args|
+          precision = extract_precision(args.last)
+          klass.new(precision: precision)
+        end
+      end
+
       def extract_scale(sql_type) # :nodoc:
         case sql_type
           when /\((\d+)\)/ then 0
@@ -453,7 +485,12 @@ module ActiveRecord
       end
 
       def extract_limit(sql_type) # :nodoc:
-        $1.to_i if sql_type =~ /\((.*)\)/
+        case sql_type
+        when /^bigint/i
+          8
+        when /\((.*)\)/
+          $1.to_i
+        end
       end
 
       def translate_exception_class(e, sql)
@@ -463,7 +500,6 @@ module ActiveRecord
           message = "#{e.class.name}: #{e.message.force_encoding sql.encoding}: #{sql}"
         end
 
-        @logger.error message if @logger
         exception = translate_exception(e, message)
         exception.set_backtrace e.backtrace
         exception
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index e9a3c26c32..251acf1c83 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -1,86 +1,29 @@
-require 'arel/visitors/bind_visitor'
+require 'active_record/connection_adapters/abstract_adapter'
+require 'active_record/connection_adapters/mysql/schema_creation'
+require 'active_record/connection_adapters/mysql/schema_definitions'
+require 'active_record/connection_adapters/mysql/schema_dumper'
+
 require 'active_support/core_ext/string/strip'
 
 module ActiveRecord
   module ConnectionAdapters
     class AbstractMysqlAdapter < AbstractAdapter
+      include MySQL::ColumnDumper
       include Savepoints
 
-      class TableDefinition < ActiveRecord::ConnectionAdapters::TableDefinition
-        def primary_key(name, type = :primary_key, options = {})
-          options[:auto_increment] ||= type == :bigint
-          super
-        end
-      end
-
-      class SchemaCreation < AbstractAdapter::SchemaCreation
-        def visit_AddColumn(o)
-          add_column_position!(super, column_options(o))
-        end
-
-        private
-
-        def visit_DropForeignKey(name)
-          "DROP FOREIGN KEY #{name}"
-        end
-
-        def visit_TableDefinition(o)
-          name = o.name
-          create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE #{quote_table_name(name)} "
-
-          statements = o.columns.map { |c| accept c }
-          statements.concat(o.indexes.map { |column_name, options| index_in_create(name, column_name, options) })
-
-          create_sql << "(#{statements.join(', ')}) " if statements.present?
-          create_sql << "#{o.options}"
-          create_sql << " AS #{@conn.to_sql(o.as)}" if o.as
-          create_sql
-        end
-
-        def visit_ChangeColumnDefinition(o)
-          change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}"
-          add_column_position!(change_column_sql, column_options(o.column))
-        end
-
-        def add_column_position!(sql, options)
-          if options[:first]
-            sql << " FIRST"
-          elsif options[:after]
-            sql << " AFTER #{quote_column_name(options[:after])}"
-          end
-          sql
-        end
-
-        def index_in_create(table_name, column_name, options)
-          index_name, index_type, index_columns, index_options, index_algorithm, index_using = @conn.add_index_options(table_name, column_name, options)
-          "#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})#{index_options} #{index_algorithm}"
-        end
+      def update_table_definition(table_name, base) # :nodoc:
+        MySQL::Table.new(table_name, base)
       end
 
       def schema_creation
-        SchemaCreation.new self
-      end
-
-      def column_spec_for_primary_key(column)
-        spec = {}
-        if column.extra == 'auto_increment'
-          return unless column.limit == 8
-          spec[:id] = ':bigint'
-        else
-          spec[:id] = column.type.inspect
-          spec.merge!(prepare_column_options(column).delete_if { |key, _| [:name, :type, :null].include?(key) })
-        end
-        spec
+        MySQL::SchemaCreation.new(self)
       end
 
       class Column < ConnectionAdapters::Column # :nodoc:
-        attr_reader :collation, :strict, :extra
+        delegate :strict, :extra, to: :sql_type_metadata, allow_nil: true
 
-        def initialize(name, default, cast_type, sql_type = nil, null = true, collation = nil, strict = false, extra = "")
-          @strict    = strict
-          @collation = collation
-          @extra     = extra
-          super(name, default, cast_type, sql_type, null)
+        def initialize(*)
+          super
           assert_valid_default(default)
           extract_default
         end
@@ -88,7 +31,7 @@ module ActiveRecord
         def extract_default
           if blob_or_text_column?
             @default = null || strict ? nil : ''
-          elsif missing_default_forged_as_empty_string?(@default)
+          elsif missing_default_forged_as_empty_string?(default)
             @default = nil
           end
         end
@@ -102,15 +45,16 @@ module ActiveRecord
           sql_type =~ /blob/i || type == :text
         end
 
+        def unsigned?
+          /unsigned/ === sql_type
+        end
+
         def case_sensitive?
           collation && !collation.match(/_ci$/)
         end
 
-        def ==(other)
-          super &&
-            collation == other.collation &&
-            strict == other.strict &&
-            extra == other.extra
+        def auto_increment?
+          extra == 'auto_increment'
         end
 
         private
@@ -131,9 +75,32 @@ module ActiveRecord
             raise ArgumentError, "#{type} columns cannot have a default value: #{default.inspect}"
           end
         end
+      end
+
+      class MysqlTypeMetadata < DelegateClass(SqlTypeMetadata) # :nodoc:
+        attr_reader :extra, :strict
+
+        def initialize(type_metadata, extra: "", strict: false)
+          super(type_metadata)
+          @type_metadata = type_metadata
+          @extra = extra
+          @strict = strict
+        end
+
+        def ==(other)
+          other.is_a?(MysqlTypeMetadata) &&
+            attributes_for_hash == other.attributes_for_hash
+        end
+        alias eql? ==
+
+        def hash
+          attributes_for_hash.hash
+        end
+
+        protected
 
         def attributes_for_hash
-          super + [collation, strict, extra]
+          [self.class, @type_metadata, extra, strict]
         end
       end
 
@@ -157,17 +124,20 @@ module ActiveRecord
       QUOTED_TRUE, QUOTED_FALSE = '1', '0'
 
       NATIVE_DATABASE_TYPES = {
-        :primary_key => "int(11) auto_increment PRIMARY KEY",
-        :string      => { :name => "varchar", :limit => 255 },
-        :text        => { :name => "text" },
-        :integer     => { :name => "int", :limit => 4 },
-        :float       => { :name => "float" },
-        :decimal     => { :name => "decimal" },
-        :datetime    => { :name => "datetime" },
-        :time        => { :name => "time" },
-        :date        => { :name => "date" },
-        :binary      => { :name => "blob" },
-        :boolean     => { :name => "tinyint", :limit => 1 }
+        primary_key: "int auto_increment PRIMARY KEY",
+        string:      { name: "varchar", limit: 255 },
+        text:        { name: "text" },
+        integer:     { name: "int", limit: 4 },
+        float:       { name: "float" },
+        decimal:     { name: "decimal" },
+        datetime:    { name: "datetime" },
+        time:        { name: "time" },
+        date:        { name: "date" },
+        binary:      { name: "blob" },
+        blob:        { name: "blob" },
+        boolean:     { name: "tinyint", limit: 1 },
+        bigint:      { name: "bigint" },
+        json:        { name: "json" },
       }
 
       INDEX_TYPES  = [:fulltext, :spatial]
@@ -183,11 +153,26 @@ module ActiveRecord
 
         if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
           @prepared_statements = true
+          @visitor.extend(DetermineIfPreparableVisitor)
         else
           @prepared_statements = false
         end
       end
 
+      MAX_INDEX_LENGTH_FOR_CHARSETS_OF_4BYTES_MAXLEN = 191
+      CHARSETS_OF_4BYTES_MAXLEN = ['utf8mb4', 'utf16', 'utf16le', 'utf32']
+      def initialize_schema_migrations_table
+        if CHARSETS_OF_4BYTES_MAXLEN.include?(charset)
+          ActiveRecord::SchemaMigration.create_table(MAX_INDEX_LENGTH_FOR_CHARSETS_OF_4BYTES_MAXLEN)
+        else
+          ActiveRecord::SchemaMigration.create_table
+        end
+      end
+
+      def version
+        @version ||= Version.new(full_version.match(/^\d+\.\d+\.\d+/)[0])
+      end
+
       # Returns true, since this connection adapter supports migrations.
       def supports_migrations?
         true
@@ -212,7 +197,11 @@ module ActiveRecord
       #
       # http://bugs.mysql.com/bug.php?id=39170
       def supports_transaction_isolation?
-        version[0] >= 5
+        version >= '5.0.0'
+      end
+
+      def supports_explain?
+        true
       end
 
       def supports_indexes_in_create?
@@ -224,7 +213,11 @@ module ActiveRecord
       end
 
       def supports_views?
-        version[0] >= 5
+        version >= '5.0.0'
+      end
+
+      def supports_datetime_with_precision?
+        version >= '5.6.4'
       end
 
       def native_database_types
@@ -243,8 +236,8 @@ module ActiveRecord
         raise NotImplementedError
       end
 
-      def new_column(field, default, cast_type, sql_type = nil, null = true, collation = "", extra = "") # :nodoc:
-        Column.new(field, default, cast_type, sql_type, null, collation, strict_mode?, extra)
+      def new_column(field, default, sql_type_metadata = nil, null = true, default_function = nil, collation = nil) # :nodoc:
+        Column.new(field, default, sql_type_metadata, null, default_function, collation)
       end
 
       # Must return the MySQL error number from the exception, if the exception has an
@@ -287,6 +280,14 @@ module ActiveRecord
         0
       end
 
+      def quoted_date(value)
+        if supports_datetime_with_precision?
+          super
+        else
+          super.sub(/\.\d{6}\z/, '')
+        end
+      end
+
       # REFERENTIAL INTEGRITY ====================================
 
       def disable_referential_integrity #:nodoc:
@@ -304,6 +305,80 @@ module ActiveRecord
       # DATABASE STATEMENTS ======================================
       #++
 
+      def explain(arel, binds = [])
+        sql     = "EXPLAIN #{to_sql(arel, binds)}"
+        start   = Time.now
+        result  = exec_query(sql, 'EXPLAIN', binds)
+        elapsed = Time.now - start
+
+        ExplainPrettyPrinter.new.pp(result, elapsed)
+      end
+
+      class ExplainPrettyPrinter # :nodoc:
+        # Pretty prints the result of an EXPLAIN in a way that resembles the output of the
+        # MySQL shell:
+        #
+        #   +----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
+        #   | id | select_type | table | type  | possible_keys | key     | key_len | ref   | rows | Extra       |
+        #   +----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
+        #   |  1 | SIMPLE      | users | const | PRIMARY       | PRIMARY | 4       | const |    1 |             |
+        #   |  1 | SIMPLE      | posts | ALL   | NULL          | NULL    | NULL    | NULL  |    1 | Using where |
+        #   +----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
+        #   2 rows in set (0.00 sec)
+        #
+        # This is an exercise in Ruby hyperrealism :).
+        def pp(result, elapsed)
+          widths    = compute_column_widths(result)
+          separator = build_separator(widths)
+
+          pp = []
+
+          pp << separator
+          pp << build_cells(result.columns, widths)
+          pp << separator
+
+          result.rows.each do |row|
+            pp << build_cells(row, widths)
+          end
+
+          pp << separator
+          pp << build_footer(result.rows.length, elapsed)
+
+          pp.join("\n") + "\n"
+        end
+
+        private
+
+        def compute_column_widths(result)
+          [].tap do |widths|
+            result.columns.each_with_index do |column, i|
+              cells_in_column = [column] + result.rows.map {|r| r[i].nil? ? 'NULL' : r[i].to_s}
+              widths << cells_in_column.map(&:length).max
+            end
+          end
+        end
+
+        def build_separator(widths)
+          padding = 1
+          '+' + widths.map {|w| '-' * (w + (padding*2))}.join('+') + '+'
+        end
+
+        def build_cells(items, widths)
+          cells = []
+          items.each_with_index do |item, i|
+            item = 'NULL' if item.nil?
+            justifier = item.is_a?(Numeric) ? 'rjust' : 'ljust'
+            cells << item.to_s.send(justifier, widths[i])
+          end
+          '| ' + cells.join(' | ') + ' |'
+        end
+
+        def build_footer(nrows, elapsed)
+          rows_label = nrows == 1 ? 'row' : 'rows'
+          "#{nrows} #{rows_label} in set (%.2f sec)" % elapsed
+        end
+      end
+
       def clear_cache!
         super
         reload_type_map
@@ -407,33 +482,45 @@ module ActiveRecord
         show_variable 'collation_database'
       end
 
-      def tables(name = nil, database = nil, like = nil) #:nodoc:
-        sql = "SHOW TABLES "
-        sql << "IN #{quote_table_name(database)} " if database
-        sql << "LIKE #{quote(like)}" if like
+      def tables(name = nil) # :nodoc:
+        sql = "SELECT table_name FROM information_schema.tables "
+        sql << "WHERE table_schema = #{quote(@config[:database])}"
 
-        execute_and_free(sql, 'SCHEMA') do |result|
-          result.collect(&:first)
-        end
+        select_values(sql, 'SCHEMA')
       end
+      alias data_sources tables
 
       def truncate(table_name, name = nil)
         execute "TRUNCATE TABLE #{quote_table_name(table_name)}", name
       end
 
-      def table_exists?(name)
-        return false unless name.present?
-        return true if tables(nil, nil, name).any?
+      def table_exists?(table_name)
+        return false unless table_name.present?
 
-        name          = name.to_s
-        schema, table = name.split('.', 2)
+        schema, name = table_name.to_s.split('.', 2)
+        schema, name = @config[:database], schema unless name # A table was provided without a schema
 
-        unless table # A table was provided without a schema
-          table  = schema
-          schema = nil
-        end
+        sql = "SELECT table_name FROM information_schema.tables "
+        sql << "WHERE table_schema = #{quote(schema)} AND table_name = #{quote(name)}"
+
+        select_values(sql, 'SCHEMA').any?
+      end
+      alias data_source_exists? table_exists?
 
-        tables(nil, schema, table).any?
+      def views # :nodoc:
+        select_values("SHOW FULL TABLES WHERE table_type = 'VIEW'", 'SCHEMA')
+      end
+
+      def view_exists?(view_name) # :nodoc:
+        return false unless view_name.present?
+
+        schema, name = view_name.to_s.split('.', 2)
+        schema, name = @config[:database], schema unless name # A view was provided without a schema
+
+        sql = "SELECT table_name FROM information_schema.tables WHERE table_type = 'VIEW'"
+        sql << " AND table_schema = #{quote(schema)} AND table_name = #{quote(name)}"
+
+        select_values(sql, 'SCHEMA').any?
       end
 
       # Returns an array of indexes for the given table.
@@ -467,8 +554,8 @@ module ActiveRecord
           each_hash(result).map do |field|
             field_name = set_field_encoding(field[:Field])
             sql_type = field[:Type]
-            cast_type = lookup_cast_type(sql_type)
-            new_column(field_name, field[:Default], cast_type, sql_type, field[:Null] == "YES", field[:Collation], field[:Extra])
+            type_metadata = fetch_type_metadata(sql_type, field[:Extra])
+            new_column(field_name, field[:Default], type_metadata, field[:Null] == "YES", nil, field[:Collation])
           end
         end
       end
@@ -501,8 +588,23 @@ module ActiveRecord
         rename_table_indexes(table_name, new_name)
       end
 
+      # Drops a table from the database.
+      #
+      # [<tt>:force</tt>]
+      #   Set to +:cascade+ to drop dependent objects as well.
+      #   Defaults to false.
+      # [<tt>:if_exists</tt>]
+      #   Set to +true+ to only drop the table if it exists.
+      #   Defaults to false.
+      # [<tt>:temporary</tt>]
+      #   Set to +true+ to drop temporary table.
+      #   Defaults to false.
+      #
+      # Although this command ignores most +options+ and the block if one is given,
+      # it can be helpful to provide these in a migration's +change+ method so it can be reverted.
+      # In that case, +options+ and the block will be used by create_table.
       def drop_table(table_name, options = {})
-        execute "DROP#{' TEMPORARY' if options[:temporary]} TABLE #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
+        execute "DROP#{' TEMPORARY' if options[:temporary]} TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
       end
 
       def rename_index(table_name, old_name, new_name)
@@ -515,12 +617,13 @@ module ActiveRecord
         end
       end
 
-      def change_column_default(table_name, column_name, default) #:nodoc:
+      def change_column_default(table_name, column_name, default_or_changes) #:nodoc:
+        default = extract_new_default_value(default_or_changes)
         column = column_for(table_name, column_name)
         change_column table_name, column_name, column.sql_type, :default => default
       end
 
-      def change_column_null(table_name, column_name, null, default = nil)
+      def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
         column = column_for(table_name, column_name)
 
         unless null || default.nil?
@@ -540,8 +643,8 @@ module ActiveRecord
       end
 
       def add_index(table_name, column_name, options = {}) #:nodoc:
-        index_name, index_type, index_columns, index_options, index_algorithm, index_using = add_index_options(table_name, column_name, options)
-        execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} ON #{quote_table_name(table_name)} (#{index_columns})#{index_options} #{index_algorithm}"
+        index_name, index_type, index_columns, _, index_algorithm, index_using = add_index_options(table_name, column_name, options)
+        execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} ON #{quote_table_name(table_name)} (#{index_columns}) #{index_algorithm}"
       end
 
       def foreign_keys(table_name)
@@ -556,7 +659,7 @@ module ActiveRecord
             AND fk.table_name = '#{table_name}'
         SQL
 
-        create_table_info = select_one("SHOW CREATE TABLE #{quote_table_name(table_name)}")["Create Table"]
+        create_table_info = create_table_info(table_name)
 
         fk_info.map do |row|
           options = {
@@ -572,68 +675,61 @@ module ActiveRecord
         end
       end
 
+      def table_options(table_name)
+        create_table_info = create_table_info(table_name)
+
+        # strip create_definitions and partition_options
+        raw_table_options = create_table_info.sub(/\A.*\n\) /m, '').sub(/\n\/\*!.*\*\/\n\z/m, '').strip
+
+        # strip AUTO_INCREMENT
+        raw_table_options.sub(/(ENGINE=\w+)(?: AUTO_INCREMENT=\d+)/, '\1')
+      end
+
       # Maps logical Rails types to MySQL-specific data types.
-      def type_to_sql(type, limit = nil, precision = nil, scale = nil)
-        case type.to_s
-        when 'binary'
-          case limit
-          when 0..0xfff;           "varbinary(#{limit})"
-          when nil;                "blob"
-          when 0x1000..0xffffffff; "blob(#{limit})"
-          else raise(ActiveRecordError, "No binary type has character length #{limit}")
-          end
+      def type_to_sql(type, limit = nil, precision = nil, scale = nil, unsigned = nil)
+        sql = case type.to_s
         when 'integer'
-          case limit
-          when 1; 'tinyint'
-          when 2; 'smallint'
-          when 3; 'mediumint'
-          when nil, 4, 11; 'int(11)'  # compatibility with MySQL default
-          when 5..8; 'bigint'
-          else raise(ActiveRecordError, "No integer type has byte size #{limit}")
-          end
+          integer_to_sql(limit)
         when 'text'
-          case limit
-          when 0..0xff;               'tinytext'
-          when nil, 0x100..0xffff;    'text'
-          when 0x10000..0xffffff;     'mediumtext'
-          when 0x1000000..0xffffffff; 'longtext'
-          else raise(ActiveRecordError, "No text type has character length #{limit}")
-          end
-        when 'datetime'
-          return super unless precision
-
-          case precision
-            when 0..6; "datetime(#{precision})"
-            else raise(ActiveRecordError, "No datetime type has precision of #{precision}. The allowed range of precision is from 0 to 6.")
+          text_to_sql(limit)
+        when 'blob'
+          binary_to_sql(limit)
+        when 'binary'
+          if (0..0xfff) === limit
+            "varbinary(#{limit})"
+          else
+            binary_to_sql(limit)
           end
         else
-          super
+          super(type, limit, precision, scale)
         end
+
+        sql << ' unsigned' if unsigned && type != :primary_key
+        sql
       end
 
       # SHOW VARIABLES LIKE 'name'
       def show_variable(name)
-        variables = select_all("SHOW VARIABLES LIKE '#{name}'", 'SCHEMA')
+        variables = select_all("select @@#{name} as 'Value'", 'SCHEMA')
         variables.first['Value'] unless variables.empty?
+      rescue ActiveRecord::StatementInvalid
+        nil
       end
 
-      # Returns a table's primary key and belonging sequence.
-      def pk_and_sequence_for(table)
-        execute_and_free("SHOW CREATE TABLE #{quote_table_name(table)}", 'SCHEMA') do |result|
-          create_table = each_hash(result).first[:"Create Table"]
-          if create_table.to_s =~ /PRIMARY KEY\s+(?:USING\s+\w+\s+)?\((.+)\)/
-            keys = $1.split(",").map { |key| key.delete('`"') }
-            keys.length == 1 ? [keys.first, nil] : nil
-          else
-            nil
-          end
-        end
-      end
+      def primary_keys(table_name) # :nodoc:
+        raise ArgumentError unless table_name.present?
 
-      # Returns just a table's primary key
-      def primary_key(table)
-        pk_and_sequence = pk_and_sequence_for(table)
-        pk_and_sequence && pk_and_sequence.first
+        schema, name = table_name.to_s.split('.', 2)
+        schema, name = @config[:database], schema unless name # A table was provided without a schema
+
+        select_values(<<-SQL.strip_heredoc, 'SCHEMA')
+          SELECT column_name
+          FROM information_schema.key_column_usage
+          WHERE constraint_name = 'PRIMARY'
+            AND table_schema = #{quote(schema)}
+            AND table_name = #{quote(name)}
+          ORDER BY ordinal_position
+        SQL
       end
 
       def case_sensitive_modifier(node, table_attribute)
@@ -682,6 +778,7 @@ module ActiveRecord
         m.register_type %r(longblob)i,   Type::Binary.new(limit: 2**32 - 1)
         m.register_type %r(^float)i,     Type::Float.new(limit: 24)
         m.register_type %r(^double)i,    Type::Float.new(limit: 53)
+        m.register_type %r(^json)i,      MysqlJson.new
 
         register_integer_type m, %r(^bigint)i,    limit: 8
         register_integer_type m, %r(^int)i,       limit: 4
@@ -690,20 +787,20 @@ module ActiveRecord
         register_integer_type m, %r(^tinyint)i,   limit: 1
 
         m.alias_type %r(tinyint\(1\))i,  'boolean' if emulate_booleans
-        m.alias_type %r(set)i,           'varchar'
         m.alias_type %r(year)i,          'integer'
         m.alias_type %r(bit)i,           'binary'
 
-        m.register_type(%r(datetime)i) do |sql_type|
-          precision = extract_precision(sql_type)
-          MysqlDateTime.new(precision: precision)
-        end
-
         m.register_type(%r(enum)i) do |sql_type|
           limit = sql_type[/^enum\((.+)\)/i, 1]
             .split(',').map{|enum| enum.strip.length - 2}.max
           MysqlString.new(limit: limit)
         end
+
+        m.register_type(%r(^set)i) do |sql_type|
+          limit = sql_type[/^set\((.+)\)/i, 1]
+            .split(',').map{|set| set.strip.length - 1}.sum - 1
+          MysqlString.new(limit: limit)
+        end
       end
 
       def register_integer_type(mapping, key, options) # :nodoc:
@@ -716,15 +813,16 @@ module ActiveRecord
         end
       end
 
-      # MySQL is too stupid to create a temporary table for use subquery, so we have
-      # to give it some prompting in the form of a subsubquery. Ugh!
-      def subquery_for(key, select)
-        subsubselect = select.clone
-        subsubselect.projections = [key]
+      def extract_precision(sql_type)
+        if /time/ === sql_type
+          super || 0
+        else
+          super
+        end
+      end
 
-        subselect = Arel::SelectManager.new(select.engine)
-        subselect.project Arel.sql(key.name)
-        subselect.from subsubselect.as('__active_record_temp')
+      def fetch_type_metadata(sql_type, extra = "")
+        MysqlTypeMetadata.new(super(sql_type), extra: extra, strict: strict_mode?)
       end
 
       def add_index_length(option_strings, column_names, options = {})
@@ -766,7 +864,7 @@ module ActiveRecord
       def add_column_sql(table_name, column_name, type, options = {})
         td = create_table_definition(table_name)
         cd = td.new_column_definition(column_name, type, options)
-        schema_creation.visit_AddColumn cd
+        schema_creation.accept(AddColumnDefinition.new(cd))
       end
 
       def change_column_sql(table_name, column_name, type, options = {})
@@ -790,7 +888,7 @@ module ActiveRecord
         options = {
           default: column.default,
           null: column.null,
-          auto_increment: column.extra == "auto_increment"
+          auto_increment: column.auto_increment?
         }
 
         current_type = select_one("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE '#{column_name}'", 'SCHEMA')["Type"]
@@ -808,8 +906,9 @@ module ActiveRecord
       end
 
       def add_index_sql(table_name, column_name, options = {})
-        index_name, index_type, index_columns = add_index_options(table_name, column_name, options)
-        "ADD #{index_type} INDEX #{index_name} (#{index_columns})"
+        index_name, index_type, index_columns, _, index_algorithm, index_using = add_index_options(table_name, column_name, options)
+        index_algorithm[0, 0] = ", " if index_algorithm.present?
+        "ADD #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})#{index_algorithm}"
       end
 
       def remove_index_sql(table_name, options = {})
@@ -827,8 +926,17 @@ module ActiveRecord
 
       private
 
-      def version
-        @version ||= full_version.scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map(&:to_i)
+      # MySQL is too stupid to create a temporary table for use subquery, so we have
+      # to give it some prompting in the form of a subsubquery. Ugh!
+      def subquery_for(key, select)
+        subsubselect = select.clone
+        subsubselect.projections = [key]
+
+        subselect = Arel::SelectManager.new(select.engine)
+        subselect.project Arel.sql(key.name)
+        # Materialized subquery by adding distinct
+        # to work with MySQL 5.7.6 which sets optimizer_switch='derived_merge=on'
+        subselect.from subsubselect.distinct.as('__active_record_temp')
       end
 
       def mariadb?
@@ -836,14 +944,13 @@ module ActiveRecord
       end
 
       def supports_rename_index?
-        mariadb? ? false : (version[0] == 5 && version[1] >= 7) || version[0] >= 6
+        mariadb? ? false : version >= '5.7.6'
       end
 
       def configure_connection
         variables = @config.fetch(:variables, {}).stringify_keys
 
-        # By default, MySQL 'where id is null' selects the last inserted id.
-        # Turn this off. http://dev.rubyonrails.org/ticket/6778
+        # By default, MySQL 'where id is null' selects the last inserted id; Turn this off.
         variables['sql_auto_is_null'] = 0
 
         # Increase timeout so the server doesn't disconnect us.
@@ -851,15 +958,17 @@ module ActiveRecord
         wait_timeout = 2147483 unless wait_timeout.is_a?(Fixnum)
         variables['wait_timeout'] = self.class.type_cast_config_to_integer(wait_timeout)
 
+        defaults = [':default', :default].to_set
+
         # Make MySQL reject illegal values rather than truncating or blanking them, see
-        # http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html#sqlmode_strict_all_tables
+        # http://dev.mysql.com/doc/refman/5.7/en/sql-mode.html#sqlmode_strict_all_tables
         # If the user has provided another value for sql_mode, don't replace it.
-        unless variables.has_key?('sql_mode')
+        unless variables.has_key?('sql_mode') || defaults.include?(@config[:strict])
           variables['sql_mode'] = strict_mode? ? 'STRICT_ALL_TABLES' : ''
         end
 
         # NAMES does not have an equals sign, see
-        # http://dev.mysql.com/doc/refman/5.0/en/set-statement.html#id944430
+        # http://dev.mysql.com/doc/refman/5.7/en/set-statement.html#id944430
         # (trailing comma because variable_assignments will always have content)
         if @config[:encoding]
           encoding = "NAMES #{@config[:encoding]}"
@@ -869,7 +978,7 @@ module ActiveRecord
 
         # Gather up all of the SET variables...
         variable_assignments = variables.map do |k, v|
-          if v == ':default' || v == :default
+          if defaults.include?(v)
             "@@SESSION.#{k} = DEFAULT" # Sets the value to the global or compile default
           elsif !v.nil?
             "@@SESSION.#{k} = #{quote(v)}"
@@ -890,28 +999,57 @@ module ActiveRecord
         end
       end
 
+      def create_table_info(table_name) # :nodoc:
+        @create_table_info_cache = {}
+        @create_table_info_cache[table_name] ||= select_one("SHOW CREATE TABLE #{quote_table_name(table_name)}")["Create Table"]
+      end
+
       def create_table_definition(name, temporary = false, options = nil, as = nil) # :nodoc:
-        TableDefinition.new(native_database_types, name, temporary, options, as)
-      end
-
-      class MysqlDateTime < Type::DateTime # :nodoc:
-        def type_cast_for_database(value)
-          if value.acts_like?(:time) && value.respond_to?(:usec)
-            result = super.to_s(:db)
-            case precision
-            when 1..6
-              "#{result}.#{sprintf("%0#{precision}d", value.usec / 10 ** (6 - precision))}"
-            else
-              result
-            end
-          else
-            super
-          end
+        MySQL::TableDefinition.new(native_database_types, name, temporary, options, as)
+      end
+
+      def integer_to_sql(limit) # :nodoc:
+        case limit
+        when 1; 'tinyint'
+        when 2; 'smallint'
+        when 3; 'mediumint'
+        when nil, 4; 'int'
+        when 5..8; 'bigint'
+        when 11; 'int(11)' # backward compatibility with Rails 2.0
+        else raise(ActiveRecordError, "No integer type has byte size #{limit}")
+        end
+      end
+
+      def text_to_sql(limit) # :nodoc:
+        case limit
+        when 0..0xff;               'tinytext'
+        when nil, 0x100..0xffff;    'text'
+        when 0x10000..0xffffff;     'mediumtext'
+        when 0x1000000..0xffffffff; 'longtext'
+        else raise(ActiveRecordError, "No text type has byte length #{limit}")
+        end
+      end
+
+      def binary_to_sql(limit) # :nodoc:
+        case limit
+        when 0..0xff;               'tinyblob'
+        when nil, 0x100..0xffff;    'blob'
+        when 0x10000..0xffffff;     'mediumblob'
+        when 0x1000000..0xffffffff; 'longblob'
+        else raise(ActiveRecordError, "No binary type has byte length #{limit}")
+        end
+      end
+
+      class MysqlJson < Type::Internal::AbstractJson # :nodoc:
+        def changed_in_place?(raw_old_value, new_value)
+          # Normalization is required because MySQL JSON data format includes
+          # the space between the elements.
+          super(serialize(deserialize(raw_old_value)), new_value)
         end
       end
 
       class MysqlString < Type::String # :nodoc:
-        def type_cast_for_database(value)
+        def serialize(value)
           case value
           when true then "1"
           when false then "0"
@@ -929,6 +1067,13 @@ module ActiveRecord
           end
         end
       end
+
+      ActiveRecord::Type.register(:json, MysqlJson, adapter: :mysql)
+      ActiveRecord::Type.register(:json, MysqlJson, adapter: :mysql2)
+      ActiveRecord::Type.register(:string, MysqlString, adapter: :mysql)
+      ActiveRecord::Type.register(:string, MysqlString, adapter: :mysql2)
+      ActiveRecord::Type.register(:unsigned_integer, Type::UnsignedInteger, adapter: :mysql)
+      ActiveRecord::Type.register(:unsigned_integer, Type::UnsignedInteger, adapter: :mysql2)
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/column.rb b/activerecord/lib/active_record/connection_adapters/column.rb
index e74de60a83..81de7c03fb 100644
--- a/activerecord/lib/active_record/connection_adapters/column.rb
+++ b/activerecord/lib/active_record/connection_adapters/column.rb
@@ -5,41 +5,32 @@ module ActiveRecord
   module ConnectionAdapters
     # An abstract definition of a column in a table.
     class Column
-      FALSE_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE', 'off', 'OFF'].to_set
+      attr_reader :name, :null, :sql_type_metadata, :default, :default_function, :collation
 
-      module Format
-        ISO_DATE = /\A(\d{4})-(\d\d)-(\d\d)\z/
-        ISO_DATETIME = /\A(\d{4})-(\d\d)-(\d\d) (\d\d):(\d\d):(\d\d)(\.\d+)?\z/
-      end
-
-      attr_reader :name, :cast_type, :null, :sql_type, :default, :default_function
-
-      delegate :type, :precision, :scale, :limit, :klass, :accessor,
-        :text?, :number?, :binary?, :changed?,
-        :type_cast_from_user, :type_cast_from_database, :type_cast_for_database,
-        :type_cast_for_schema,
-        to: :cast_type
+      delegate :precision, :scale, :limit, :type, :sql_type, to: :sql_type_metadata, allow_nil: true
 
       # Instantiates a new column in the table.
       #
-      # +name+ is the column's name, such as <tt>supplier_id</tt> in <tt>supplier_id int(11)</tt>.
+      # +name+ is the column's name, such as <tt>supplier_id</tt> in <tt>supplier_id int</tt>.
       # +default+ is the type-casted default value, such as +new+ in <tt>sales_stage varchar(20) default 'new'</tt>.
-      # +cast_type+ is the object used for type casting and type information.
-      # +sql_type+ is used to extract the column's length, if necessary. For example +60+ in
-      # <tt>company_name varchar(60)</tt>.
-      # It will be mapped to one of the standard Rails SQL types in the <tt>type</tt> attribute.
+      # +sql_type_metadata+ is various information about the type of the column
       # +null+ determines if this column allows +NULL+ values.
-      def initialize(name, default, cast_type, sql_type = nil, null = true, default_function = nil)
-        @name             = name
-        @cast_type        = cast_type
-        @sql_type         = sql_type
-        @null             = null
-        @default          = default
+      def initialize(name, default, sql_type_metadata = nil, null = true, default_function = nil, collation = nil)
+        @name = name.freeze
+        @sql_type_metadata = sql_type_metadata
+        @null = null
+        @default = default
         @default_function = default_function
+        @collation = collation
+        @table_name = nil
       end
 
       def has_default?
-        !default.nil?
+        !default.nil? || default_function
+      end
+
+      def bigint?
+        /bigint/ === sql_type
       end
 
       # Returns the human name of the column name.
@@ -50,19 +41,9 @@ module ActiveRecord
         Base.human_attribute_name(@name)
       end
 
-      def with_type(type)
-        dup.tap do |clone|
-          clone.instance_variable_set('@cast_type', type)
-        end
-      end
-
       def ==(other)
-        other.name == name &&
-          other.default == default &&
-          other.cast_type == cast_type &&
-          other.sql_type == sql_type &&
-          other.null == null &&
-          other.default_function == default_function
+        other.is_a?(Column) &&
+          attributes_for_hash == other.attributes_for_hash
       end
       alias :eql? :==
 
@@ -70,16 +51,16 @@ module ActiveRecord
         attributes_for_hash.hash
       end
 
-      private
+      protected
 
       def attributes_for_hash
-        [self.class, name, default, cast_type, sql_type, null, default_function]
+        [self.class, name, default, sql_type_metadata, null, default_function, collation]
       end
     end
 
     class NullColumn < Column
       def initialize(name)
-        super name, nil, Type::Value.new
+        super(name, nil)
       end
     end
   end
diff --git a/activerecord/lib/active_record/connection_adapters/determine_if_preparable_visitor.rb b/activerecord/lib/active_record/connection_adapters/determine_if_preparable_visitor.rb
new file mode 100644
index 0000000000..0fdc185c45
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/determine_if_preparable_visitor.rb
@@ -0,0 +1,22 @@
+module ActiveRecord
+  module ConnectionAdapters
+    module DetermineIfPreparableVisitor
+      attr_reader :preparable
+
+      def accept(*)
+        @preparable = true
+        super
+      end
+
+      def visit_Arel_Nodes_In(*)
+        @preparable = false
+        super
+      end
+
+      def visit_Arel_Nodes_SqlLiteral(*)
+        @preparable = false
+        super
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
new file mode 100644
index 0000000000..1e2c859af9
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
@@ -0,0 +1,57 @@
+module ActiveRecord
+  module ConnectionAdapters
+    module MySQL
+      class SchemaCreation < AbstractAdapter::SchemaCreation
+        private
+
+        def visit_DropForeignKey(name)
+          "DROP FOREIGN KEY #{name}"
+        end
+
+        def visit_ColumnDefinition(o)
+          o.sql_type = type_to_sql(o.type, o.limit, o.precision, o.scale, o.unsigned)
+          super
+        end
+
+        def visit_AddColumnDefinition(o)
+          add_column_position!(super, column_options(o.column))
+        end
+
+        def visit_ChangeColumnDefinition(o)
+          change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}"
+          add_column_position!(change_column_sql, column_options(o.column))
+        end
+
+        def column_options(o)
+          column_options = super
+          column_options[:charset] = o.charset
+          column_options
+        end
+
+        def add_column_options!(sql, options)
+          if options[:charset]
+            sql << " CHARACTER SET #{options[:charset]}"
+          end
+          if options[:collation]
+            sql << " COLLATE #{options[:collation]}"
+          end
+          super
+        end
+
+        def add_column_position!(sql, options)
+          if options[:first]
+            sql << " FIRST"
+          elsif options[:after]
+            sql << " AFTER #{quote_column_name(options[:after])}"
+          end
+          sql
+        end
+
+        def index_in_create(table_name, column_name, options)
+          index_name, index_type, index_columns, _, _, index_using = @conn.add_index_options(table_name, column_name, options)
+          "#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns}) "
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
new file mode 100644
index 0000000000..29e8c73d46
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
@@ -0,0 +1,69 @@
+module ActiveRecord
+  module ConnectionAdapters
+    module MySQL
+      module ColumnMethods
+        def primary_key(name, type = :primary_key, **options)
+          options[:auto_increment] = true if type == :bigint
+          super
+        end
+
+        def blob(*args, **options)
+          args.each { |name| column(name, :blob, options) }
+        end
+
+        def json(*args, **options)
+          args.each { |name| column(name, :json, options) }
+        end
+
+        def unsigned_integer(*args, **options)
+          args.each { |name| column(name, :unsigned_integer, options) }
+        end
+
+        def unsigned_bigint(*args, **options)
+          args.each { |name| column(name, :unsigned_bigint, options) }
+        end
+
+        def unsigned_float(*args, **options)
+          args.each { |name| column(name, :unsigned_float, options) }
+        end
+
+        def unsigned_decimal(*args, **options)
+          args.each { |name| column(name, :unsigned_decimal, options) }
+        end
+      end
+
+      class ColumnDefinition < ActiveRecord::ConnectionAdapters::ColumnDefinition
+        attr_accessor :charset, :unsigned
+      end
+
+      class TableDefinition < ActiveRecord::ConnectionAdapters::TableDefinition
+        include ColumnMethods
+
+        def new_column_definition(name, type, options) # :nodoc:
+          column = super
+          case column.type
+          when :primary_key
+            column.type = :integer
+            column.auto_increment = true
+          when /\Aunsigned_(?<type>.+)\z/
+            column.type = $~[:type].to_sym
+            column.unsigned = true
+          end
+          column.unsigned ||= options[:unsigned]
+          column.charset = options[:charset]
+          column
+        end
+
+        private
+
+        def create_column_definition(name, type)
+          MySQL::ColumnDefinition.new(name, type)
+        end
+      end
+
+      class Table < ActiveRecord::ConnectionAdapters::Table
+        include ColumnMethods
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
new file mode 100644
index 0000000000..3c48d0554e
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
@@ -0,0 +1,56 @@
+module ActiveRecord
+  module ConnectionAdapters
+    module MySQL
+      module ColumnDumper
+        def column_spec_for_primary_key(column)
+          spec = {}
+          if column.auto_increment?
+            spec[:id] = ':bigint' if column.bigint?
+            spec[:unsigned] = 'true' if column.unsigned?
+            return if spec.empty?
+          else
+            spec[:id] = column.type.inspect
+            spec.merge!(prepare_column_options(column).delete_if { |key, _| [:name, :type, :null].include?(key) })
+          end
+          spec
+        end
+
+        def prepare_column_options(column)
+          spec = super
+          spec[:unsigned] = 'true' if column.unsigned?
+          spec
+        end
+
+        def migration_keys
+          super + [:unsigned]
+        end
+
+        private
+
+        def schema_type(column)
+          if column.sql_type == 'tinyblob'
+            'blob'
+          else
+            super
+          end
+        end
+
+        def schema_limit(column)
+          super unless column.type == :boolean
+        end
+
+        def schema_precision(column)
+          super unless /time/ === column.sql_type && column.precision == 0
+        end
+
+        def schema_collation(column)
+          if column.collation && table_name = column.instance_variable_get(:@table_name)
+            @table_collation_cache ||= {}
+            @table_collation_cache[table_name] ||= select_one("SHOW TABLE STATUS LIKE '#{table_name}'")["Collation"]
+            column.collation.inspect if column.collation != @table_collation_cache[table_name]
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
index 75f244b3f3..42c4a14f00 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
@@ -1,6 +1,6 @@
 require 'active_record/connection_adapters/abstract_mysql_adapter'
 
-gem 'mysql2', '~> 0.3.13'
+gem 'mysql2', '>= 0.3.18', '< 0.5'
 require 'mysql2'
 
 module ActiveRecord
@@ -37,17 +37,8 @@ module ActiveRecord
         configure_connection
       end
 
-      MAX_INDEX_LENGTH_FOR_UTF8MB4 = 191
-      def initialize_schema_migrations_table
-        if @config[:encoding] == 'utf8mb4'
-          ActiveRecord::SchemaMigration.create_table(MAX_INDEX_LENGTH_FOR_UTF8MB4)
-        else
-          ActiveRecord::SchemaMigration.create_table
-        end
-      end
-
-      def supports_explain?
-        true
+      def supports_json?
+        version >= '5.7.8'
       end
 
       # HELPER METHODS ===========================================
@@ -104,80 +95,6 @@ module ActiveRecord
       # DATABASE STATEMENTS ======================================
       #++
 
-      def explain(arel, binds = [])
-        sql     = "EXPLAIN #{to_sql(arel, binds.dup)}"
-        start   = Time.now
-        result  = exec_query(sql, 'EXPLAIN', binds)
-        elapsed = Time.now - start
-
-        ExplainPrettyPrinter.new.pp(result, elapsed)
-      end
-
-      class ExplainPrettyPrinter # :nodoc:
-        # Pretty prints the result of a EXPLAIN in a way that resembles the output of the
-        # MySQL shell:
-        #
-        #   +----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
-        #   | id | select_type | table | type  | possible_keys | key     | key_len | ref   | rows | Extra       |
-        #   +----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
-        #   |  1 | SIMPLE      | users | const | PRIMARY       | PRIMARY | 4       | const |    1 |             |
-        #   |  1 | SIMPLE      | posts | ALL   | NULL          | NULL    | NULL    | NULL  |    1 | Using where |
-        #   +----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
-        #   2 rows in set (0.00 sec)
-        #
-        # This is an exercise in Ruby hyperrealism :).
-        def pp(result, elapsed)
-          widths    = compute_column_widths(result)
-          separator = build_separator(widths)
-
-          pp = []
-
-          pp << separator
-          pp << build_cells(result.columns, widths)
-          pp << separator
-
-          result.rows.each do |row|
-            pp << build_cells(row, widths)
-          end
-
-          pp << separator
-          pp << build_footer(result.rows.length, elapsed)
-
-          pp.join("\n") + "\n"
-        end
-
-        private
-
-        def compute_column_widths(result)
-          [].tap do |widths|
-            result.columns.each_with_index do |column, i|
-              cells_in_column = [column] + result.rows.map {|r| r[i].nil? ? 'NULL' : r[i].to_s}
-              widths << cells_in_column.map(&:length).max
-            end
-          end
-        end
-
-        def build_separator(widths)
-          padding = 1
-          '+' + widths.map {|w| '-' * (w + (padding*2))}.join('+') + '+'
-        end
-
-        def build_cells(items, widths)
-          cells = []
-          items.each_with_index do |item, i|
-            item = 'NULL' if item.nil?
-            justifier = item.is_a?(Numeric) ? 'rjust' : 'ljust'
-            cells << item.to_s.send(justifier, widths[i])
-          end
-          '| ' + cells.join(' | ') + ' |'
-        end
-
-        def build_footer(nrows, elapsed)
-          rows_label = nrows == 1 ? 'row' : 'rows'
-          "#{nrows} #{rows_label} in set (%.2f sec)" % elapsed
-        end
-      end
-
       # FIXME: re-enable the following once a "better" query_cache solution is in core
       #
       # The overrides below perform much better than the originals in AbstractAdapter
@@ -209,7 +126,9 @@ module ActiveRecord
       # Returns an array of arrays containing the field values.
       # Order is the same as that returned by +columns+.
       def select_rows(sql, name = nil, binds = [])
-        execute(sql, name).to_a
+        result = execute(sql, name)
+        @connection.next_result while @connection.more_results?
+        result.to_a
       end
 
       # Executes the SQL statement in the context of this connection.
@@ -223,8 +142,9 @@ module ActiveRecord
         super
       end
 
-      def exec_query(sql, name = 'SQL', binds = [])
+      def exec_query(sql, name = 'SQL', binds = [], prepare: false)
         result = execute(sql, name)
+        @connection.next_result while @connection.more_results?
         ActiveRecord::Result.new(result.fields, result.to_a)
       end
 
@@ -263,7 +183,7 @@ module ActiveRecord
       end
 
       def full_version
-        @full_version ||= @connection.info[:version]
+        @full_version ||= @connection.server_info[:version]
       end
 
       def set_field_encoding field_name
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 23d8389abb..fddb318553 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -5,8 +5,10 @@ require 'active_support/core_ext/hash/keys'
 gem 'mysql', '~> 2.9'
 require 'mysql'
 
-class Mysql
+class Mysql # :nodoc: all
   class Time
+    # Used for casting DateTime fields to a MySQL friendly Time.
+    # This was documented in 48498da0dfed5239ea1eafb243ce47d7e3ce9e8e
     def to_date
       Date.new(year, month, day)
     end
@@ -56,9 +58,9 @@ module ActiveRecord
     # * <tt>:password</tt> - Defaults to nothing.
     # * <tt>:database</tt> - The name of the database. No default, must be provided.
     # * <tt>:encoding</tt> - (Optional) Sets the client encoding by executing "SET NAMES <encoding>" after connection.
-    # * <tt>:reconnect</tt> - Defaults to false (See MySQL documentation: http://dev.mysql.com/doc/refman/5.0/en/auto-reconnect.html).
-    # * <tt>:strict</tt> - Defaults to true. Enable STRICT_ALL_TABLES. (See MySQL documentation: http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html)
-    # * <tt>:variables</tt> - (Optional) A hash session variables to send as <tt>SET @@SESSION.key = value</tt> on each database connection. Use the value +:default+ to set a variable to its DEFAULT value. (See MySQL documentation: http://dev.mysql.com/doc/refman/5.0/en/set-statement.html).
+    # * <tt>:reconnect</tt> - Defaults to false (See MySQL documentation: http://dev.mysql.com/doc/refman/5.7/en/auto-reconnect.html).
+    # * <tt>:strict</tt> - Defaults to true. Enable STRICT_ALL_TABLES. (See MySQL documentation: http://dev.mysql.com/doc/refman/5.7/en/sql-mode.html)
+    # * <tt>:variables</tt> - (Optional) A hash session variables to send as <tt>SET @@SESSION.key = value</tt> on each database connection. Use the value +:default+ to set a variable to its DEFAULT value. (See MySQL documentation: http://dev.mysql.com/doc/refman/5.7/en/set-statement.html).
     # * <tt>:sslca</tt> - Necessary to use MySQL with an SSL connection.
     # * <tt>:sslkey</tt> - Necessary to use MySQL with an SSL connection.
     # * <tt>:sslcert</tt> - Necessary to use MySQL with an SSL connection.
@@ -69,41 +71,16 @@ module ActiveRecord
       ADAPTER_NAME = 'MySQL'.freeze
 
       class StatementPool < ConnectionAdapters::StatementPool
-        def initialize(connection, max = 1000)
-          super
-          @cache = Hash.new { |h,pid| h[pid] = {} }
-        end
-
-        def each(&block); cache.each(&block); end
-        def key?(key);    cache.key?(key); end
-        def [](key);      cache[key]; end
-        def length;       cache.length; end
-        def delete(key);  cache.delete(key); end
-
-        def []=(sql, key)
-          while @max <= cache.size
-            cache.shift.last[:stmt].close
-          end
-          cache[sql] = key
-        end
-
-        def clear
-          cache.each_value do |hash|
-            hash[:stmt].close
-          end
-          cache.clear
-        end
-
         private
-        def cache
-          @cache[Process.pid]
+
+        def dealloc(stmt)
+          stmt[:stmt].close
         end
       end
 
       def initialize(connection, logger, connection_options, config)
         super
-        @statements = StatementPool.new(@connection,
-                                        self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
+        @statements = StatementPool.new(self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
         @client_encoding = nil
         connect
       end
@@ -184,6 +161,14 @@ module ActiveRecord
       # DATABASE STATEMENTS ======================================
       #++
 
+      def select_all(arel, name = nil, binds = [])
+        if ExplainRegistry.collect? && prepared_statements
+          unprepared_statement { super }
+        else
+          super
+        end
+      end
+
       def select_rows(sql, name = nil, binds = [])
         @connection.query_with_result = true
         rows = exec_query(sql, name, binds).rows
@@ -245,16 +230,16 @@ module ActiveRecord
         return @client_encoding if @client_encoding
 
         result = exec_query(
-          "SHOW VARIABLES WHERE Variable_name = 'character_set_client'",
+          "select @@character_set_client",
           'SCHEMA')
         @client_encoding = ENCODINGS[result.rows.last.last]
       end
 
-      def exec_query(sql, name = 'SQL', binds = [])
+      def exec_query(sql, name = 'SQL', binds = [], prepare: false)
         if without_prepared_statement?(binds)
           result_set, affected_rows = exec_without_stmt(sql, name)
         else
-          result_set, affected_rows = exec_stmt(sql, name, binds)
+          result_set, affected_rows = exec_stmt(sql, name, binds, cache_stmt: prepare)
         end
 
         yield affected_rows if block_given?
@@ -328,8 +313,8 @@ module ActiveRecord
 
       def initialize_type_map(m) # :nodoc:
         super
-        m.register_type %r(datetime)i, Fields::DateTime.new
-        m.register_type %r(time)i,     Fields::Time.new
+        register_class_with_precision m, %r(datetime)i, Fields::DateTime
+        register_class_with_precision m, %r(time)i,     Fields::Time
       end
 
       def exec_without_stmt(sql, name = 'SQL') # :nodoc:
@@ -393,14 +378,12 @@ module ActiveRecord
 
       private
 
-      def exec_stmt(sql, name, binds)
+      def exec_stmt(sql, name, binds, cache_stmt: false)
         cache = {}
-        type_casted_binds = binds.map { |col, val|
-          [col, type_cast(val, col)]
-        }
+        type_casted_binds = binds.map { |attr| type_cast(attr.value_for_database) }
 
-        log(sql, name, type_casted_binds) do
-          if binds.empty?
+        log(sql, name, binds) do
+          if !cache_stmt
             stmt = @connection.prepare(sql)
           else
             cache = @statements[sql] ||= {
@@ -410,14 +393,17 @@ module ActiveRecord
           end
 
           begin
-            stmt.execute(*type_casted_binds.map { |_, val| val })
+            stmt.execute(*type_casted_binds)
           rescue Mysql::Error => e
             # Older versions of MySQL leave the prepared statement in a bad
             # place when an error occurs. To support older MySQL versions, we
             # need to close the statement and delete the statement from the
             # cache.
-            stmt.close
-            @statements.delete sql
+            if !cache_stmt
+              stmt.close
+            else
+              @statements.delete sql
+            end
             raise e
           end
 
@@ -431,7 +417,7 @@ module ActiveRecord
           affected_rows = stmt.affected_rows
 
           stmt.free_result
-          stmt.close if binds.empty?
+          stmt.close if !cache_stmt
 
           [result_set, affected_rows]
         end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/array_parser.rb b/activerecord/lib/active_record/connection_adapters/postgresql/array_parser.rb
deleted file mode 100644
index 1b74c039ce..0000000000
--- a/activerecord/lib/active_record/connection_adapters/postgresql/array_parser.rb
+++ /dev/null
@@ -1,93 +0,0 @@
-module ActiveRecord
-  module ConnectionAdapters
-    module PostgreSQL
-      module ArrayParser # :nodoc:
-
-        DOUBLE_QUOTE = '"'
-        BACKSLASH = "\\"
-        COMMA = ','
-        BRACKET_OPEN = '{'
-        BRACKET_CLOSE = '}'
-
-        def parse_pg_array(string) # :nodoc:
-          local_index = 0
-          array = []
-          while(local_index < string.length)
-            case string[local_index]
-            when BRACKET_OPEN
-              local_index,array = parse_array_contents(array, string, local_index + 1)
-            when BRACKET_CLOSE
-              return array
-            end
-            local_index += 1
-          end
-
-          array
-        end
-
-        private
-
-          def parse_array_contents(array, string, index)
-            is_escaping  = false
-            is_quoted    = false
-            was_quoted   = false
-            current_item = ''
-
-            local_index = index
-            while local_index
-              token = string[local_index]
-              if is_escaping
-                current_item << token
-                is_escaping = false
-              else
-                if is_quoted
-                  case token
-                  when DOUBLE_QUOTE
-                    is_quoted = false
-                    was_quoted = true
-                  when BACKSLASH
-                    is_escaping = true
-                  else
-                    current_item << token
-                  end
-                else
-                  case token
-                  when BACKSLASH
-                    is_escaping = true
-                  when COMMA
-                    add_item_to_array(array, current_item, was_quoted)
-                    current_item = ''
-                    was_quoted = false
-                  when DOUBLE_QUOTE
-                    is_quoted = true
-                  when BRACKET_OPEN
-                    internal_items = []
-                    local_index,internal_items = parse_array_contents(internal_items, string, local_index + 1)
-                    array.push(internal_items)
-                  when BRACKET_CLOSE
-                    add_item_to_array(array, current_item, was_quoted)
-                    return local_index,array
-                  else
-                    current_item << token
-                  end
-                end
-              end
-
-              local_index += 1
-            end
-            return local_index,array
-          end
-
-          def add_item_to_array(array, current_item, quoted)
-            return if !quoted && current_item.length == 0
-
-            if !quoted && current_item == 'NULL'
-              array.push nil
-            else
-              array.push current_item
-            end
-          end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/column.rb b/activerecord/lib/active_record/connection_adapters/postgresql/column.rb
index acb1278499..bfa03fa136 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/column.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/column.rb
@@ -2,21 +2,14 @@ module ActiveRecord
   module ConnectionAdapters
     # PostgreSQL-specific extensions to column definitions in a table.
     class PostgreSQLColumn < Column #:nodoc:
-      attr_reader :array
+      delegate :array, :oid, :fmod, to: :sql_type_metadata
       alias :array? :array
 
-      def initialize(name, default, cast_type, sql_type = nil, null = true, default_function = nil)
-        if sql_type =~ /\[\]$/
-          @array = true
-          sql_type = sql_type[0..sql_type.length - 3]
-        else
-          @array = false
-        end
-        super
-      end
-
       def serial?
-        default_function && default_function =~ /\Anextval\(.*\)\z/
+        return unless default_function
+
+        table_name = @table_name || '(?<table_name>.+)'
+        %r{\Anextval\('"?#{table_name}_#{name}_seq"?'::regclass\)\z} === default_function
       end
     end
   end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
index 11d3f5301a..0e0c0e993a 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
@@ -8,7 +8,7 @@ module ActiveRecord
         end
 
         class ExplainPrettyPrinter # :nodoc:
-          # Pretty prints the result of a EXPLAIN in a way that resembles the output of the
+          # Pretty prints the result of an EXPLAIN in a way that resembles the output of the
           # PostgreSQL shell:
           #
           #                                     QUERY PLAN
@@ -156,8 +156,8 @@ module ActiveRecord
           end
         end
 
-        def exec_query(sql, name = 'SQL', binds = [])
-          execute_and_clear(sql, name, binds) do |result|
+        def exec_query(sql, name = 'SQL', binds = [], prepare: false)
+          execute_and_clear(sql, name, binds, prepare: prepare) do |result|
             types = {}
             fields = result.fields
             fields.each_with_index do |fname, i|
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
index d28a2b4fa0..68752cdd80 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
@@ -1,25 +1,20 @@
-require 'active_record/connection_adapters/postgresql/oid/infinity'
-
 require 'active_record/connection_adapters/postgresql/oid/array'
 require 'active_record/connection_adapters/postgresql/oid/bit'
 require 'active_record/connection_adapters/postgresql/oid/bit_varying'
 require 'active_record/connection_adapters/postgresql/oid/bytea'
 require 'active_record/connection_adapters/postgresql/oid/cidr'
-require 'active_record/connection_adapters/postgresql/oid/date'
 require 'active_record/connection_adapters/postgresql/oid/date_time'
 require 'active_record/connection_adapters/postgresql/oid/decimal'
 require 'active_record/connection_adapters/postgresql/oid/enum'
-require 'active_record/connection_adapters/postgresql/oid/float'
 require 'active_record/connection_adapters/postgresql/oid/hstore'
 require 'active_record/connection_adapters/postgresql/oid/inet'
-require 'active_record/connection_adapters/postgresql/oid/integer'
 require 'active_record/connection_adapters/postgresql/oid/json'
 require 'active_record/connection_adapters/postgresql/oid/jsonb'
 require 'active_record/connection_adapters/postgresql/oid/money'
 require 'active_record/connection_adapters/postgresql/oid/point'
+require 'active_record/connection_adapters/postgresql/oid/rails_5_1_point'
 require 'active_record/connection_adapters/postgresql/oid/range'
 require 'active_record/connection_adapters/postgresql/oid/specialized_string'
-require 'active_record/connection_adapters/postgresql/oid/time'
 require 'active_record/connection_adapters/postgresql/oid/uuid'
 require 'active_record/connection_adapters/postgresql/oid/vector'
 require 'active_record/connection_adapters/postgresql/oid/xml'
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/array.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/array.rb
index e45a2f59d9..25961a9869 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/array.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/array.rb
@@ -3,51 +3,53 @@ module ActiveRecord
     module PostgreSQL
       module OID # :nodoc:
         class Array < Type::Value # :nodoc:
-          include Type::Mutable
-
-          # Loads pg_array_parser if available. String parsing can be
-          # performed quicker by a native extension, which will not create
-          # a large amount of Ruby objects that will need to be garbage
-          # collected. pg_array_parser has a C and Java extension
-          begin
-            require 'pg_array_parser'
-            include PgArrayParser
-          rescue LoadError
-            require 'active_record/connection_adapters/postgresql/array_parser'
-            include PostgreSQL::ArrayParser
-          end
+          include Type::Helpers::Mutable
 
           attr_reader :subtype, :delimiter
-          delegate :type, :user_input_in_time_zone, to: :subtype
+          delegate :type, :user_input_in_time_zone, :limit, to: :subtype
 
           def initialize(subtype, delimiter = ',')
             @subtype = subtype
             @delimiter = delimiter
+
+            @pg_encoder = PG::TextEncoder::Array.new name: "#{type}[]", delimiter: delimiter
+            @pg_decoder = PG::TextDecoder::Array.new name: "#{type}[]", delimiter: delimiter
           end
 
-          def type_cast_from_database(value)
+          def deserialize(value)
             if value.is_a?(::String)
-              type_cast_array(parse_pg_array(value), :type_cast_from_database)
+              type_cast_array(@pg_decoder.decode(value), :deserialize)
             else
               super
             end
           end
 
-          def type_cast_from_user(value)
+          def cast(value)
             if value.is_a?(::String)
-              value = parse_pg_array(value)
+              value = @pg_decoder.decode(value)
             end
-            type_cast_array(value, :type_cast_from_user)
+            type_cast_array(value, :cast)
           end
 
-          def type_cast_for_database(value)
+          def serialize(value)
             if value.is_a?(::Array)
-              cast_value_for_database(value)
+              @pg_encoder.encode(type_cast_array(value, :serialize))
             else
               super
             end
           end
 
+          def ==(other)
+            other.is_a?(Array) &&
+              subtype == other.subtype &&
+              delimiter == other.delimiter
+          end
+
+          def type_cast_for_schema(value)
+            return super unless value.is_a?(::Array)
+            "[" + value.map { |v| subtype.type_cast_for_schema(v) }.join(", ") + "]"
+          end
+
           private
 
           def type_cast_array(value, method)
@@ -57,41 +59,6 @@ module ActiveRecord
               @subtype.public_send(method, value)
             end
           end
-
-          def cast_value_for_database(value)
-            if value.is_a?(::Array)
-              casted_values = value.map { |item| cast_value_for_database(item) }
-              "{#{casted_values.join(delimiter)}}"
-            else
-              quote_and_escape(subtype.type_cast_for_database(value))
-            end
-          end
-
-          ARRAY_ESCAPE = "\\" * 2 * 2 # escape the backslash twice for PG arrays
-
-          def quote_and_escape(value)
-            case value
-            when ::String
-              if string_requires_quoting?(value)
-                value = value.gsub(/\\/, ARRAY_ESCAPE)
-                value.gsub!(/"/,"\\\"")
-                %("#{value}")
-              else
-                value
-              end
-            when nil then "NULL"
-            else value
-            end
-          end
-
-          # See http://www.postgresql.org/docs/9.2/static/arrays.html#ARRAYS-IO
-          # for a list of all cases in which strings will be quoted.
-          def string_requires_quoting?(string)
-            string.empty? ||
-              string == "NULL" ||
-              string =~ /[\{\}"\\\s]/ ||
-              string.include?(delimiter)
-          end
         end
       end
     end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/bit.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/bit.rb
index 1dbb40ca1d..ea0fa2517f 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/bit.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/bit.rb
@@ -7,7 +7,7 @@ module ActiveRecord
             :bit
           end
 
-          def type_cast(value)
+          def cast(value)
             if ::String === value
               case value
               when /^0x/i
@@ -20,7 +20,7 @@ module ActiveRecord
             end
           end
 
-          def type_cast_for_database(value)
+          def serialize(value)
             Data.new(super) if value
           end
 
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/bytea.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/bytea.rb
index 6bd1b8ecae..8f9d6e7f9b 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/bytea.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/bytea.rb
@@ -3,7 +3,7 @@ module ActiveRecord
     module PostgreSQL
       module OID # :nodoc:
         class Bytea < Type::Binary # :nodoc:
-          def type_cast_from_database(value)
+          def deserialize(value)
             return if value.nil?
             return value.to_s if value.is_a?(Type::Binary::Data)
             PGconn.unescape_bytea(super)
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/cidr.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/cidr.rb
index 222f10fa8f..eeccb09bdf 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/cidr.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/cidr.rb
@@ -18,7 +18,7 @@ module ActiveRecord
             end
           end
 
-          def type_cast_for_database(value)
+          def serialize(value)
             if IPAddr === value
               "#{value}/#{value.instance_variable_get(:@mask_addr).to_s(2).count('1')}"
             else
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/date.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/date.rb
deleted file mode 100644
index 1d8d264530..0000000000
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/date.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-module ActiveRecord
-  module ConnectionAdapters
-    module PostgreSQL
-      module OID # :nodoc:
-        class Date < Type::Date # :nodoc:
-          include Infinity
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/date_time.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/date_time.rb
index b9e7894e5c..424769f765 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/date_time.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/date_time.rb
@@ -3,21 +3,15 @@ module ActiveRecord
     module PostgreSQL
       module OID # :nodoc:
         class DateTime < Type::DateTime # :nodoc:
-          include Infinity
-
           def cast_value(value)
-            if value.is_a?(::String)
-              case value
-              when 'infinity' then ::Float::INFINITY
-              when '-infinity' then -::Float::INFINITY
-              when / BC$/
-                astronomical_year = format("%04d", -value[/^\d+/].to_i + 1)
-                super(value.sub(/ BC$/, "").sub(/^\d+/, astronomical_year))
-              else
-                super
-              end
+            case value
+            when 'infinity' then ::Float::INFINITY
+            when '-infinity' then -::Float::INFINITY
+            when / BC$/
+              astronomical_year = format("%04d", -value[/^\d+/].to_i + 1)
+              super(value.sub(/ BC$/, "").sub(/^\d+/, astronomical_year))
             else
-              value
+              super
             end
           end
         end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/enum.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/enum.rb
index 77d5038efd..91d339f32c 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/enum.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/enum.rb
@@ -7,7 +7,9 @@ module ActiveRecord
             :enum
           end
 
-          def type_cast(value)
+          private
+
+          def cast_value(value)
             value.to_s
           end
         end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/float.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/float.rb
deleted file mode 100644
index 78ef94b912..0000000000
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/float.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-module ActiveRecord
-  module ConnectionAdapters
-    module PostgreSQL
-      module OID # :nodoc:
-        class Float < Type::Float # :nodoc:
-          include Infinity
-
-          def cast_value(value)
-            case value
-            when ::Float then     value
-            when 'Infinity' then  ::Float::INFINITY
-            when '-Infinity' then -::Float::INFINITY
-            when 'NaN' then       ::Float::NAN
-            else                  value.to_f
-            end
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/hstore.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/hstore.rb
index be4525c94f..9270fc9f21 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/hstore.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/hstore.rb
@@ -3,13 +3,13 @@ module ActiveRecord
     module PostgreSQL
       module OID # :nodoc:
         class Hstore < Type::Value # :nodoc:
-          include Type::Mutable
+          include Type::Helpers::Mutable
 
           def type
             :hstore
           end
 
-          def type_cast_from_database(value)
+          def deserialize(value)
             if value.is_a?(::String)
               ::Hash[value.scan(HstorePair).map { |k, v|
                 v = v.upcase == 'NULL' ? nil : v.gsub(/\A"(.*)"\Z/m,'\1').gsub(/\\(.)/, '\1')
@@ -21,7 +21,7 @@ module ActiveRecord
             end
           end
 
-          def type_cast_for_database(value)
+          def serialize(value)
             if value.is_a?(::Hash)
               value.map { |k, v| "#{escape_hstore(k)}=>#{escape_hstore(v)}" }.join(', ')
             else
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/infinity.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/infinity.rb
deleted file mode 100644
index e47780399a..0000000000
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/infinity.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-module ActiveRecord
-  module ConnectionAdapters
-    module PostgreSQL
-      module OID # :nodoc:
-        module Infinity # :nodoc:
-          def infinity(options = {})
-            options[:negative] ? -::Float::INFINITY : ::Float::INFINITY
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/integer.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/integer.rb
deleted file mode 100644
index 59abdc0009..0000000000
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/integer.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-module ActiveRecord
-  module ConnectionAdapters
-    module PostgreSQL
-      module OID # :nodoc:
-        class Integer < Type::Integer # :nodoc:
-          include Infinity
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/json.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/json.rb
index e12ddd9901..dbc879ffd4 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/json.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/json.rb
@@ -2,32 +2,7 @@ module ActiveRecord
   module ConnectionAdapters
     module PostgreSQL
       module OID # :nodoc:
-        class Json < Type::Value # :nodoc:
-          include Type::Mutable
-
-          def type
-            :json
-          end
-
-          def type_cast_from_database(value)
-            if value.is_a?(::String)
-              ::ActiveSupport::JSON.decode(value)
-            else
-              super
-            end
-          end
-
-          def type_cast_for_database(value)
-            if value.is_a?(::Array) || value.is_a?(::Hash)
-              ::ActiveSupport::JSON.encode(value)
-            else
-              super
-            end
-          end
-
-          def accessor
-            ActiveRecord::Store::StringKeyedHashAccessor
-          end
+        class Json < Type::Internal::AbstractJson
         end
       end
     end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/jsonb.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/jsonb.rb
index 380c50fc14..87391b5dc7 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/jsonb.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/jsonb.rb
@@ -9,11 +9,11 @@ module ActiveRecord
 
           def changed_in_place?(raw_old_value, new_value)
             # Postgres does not preserve insignificant whitespaces when
-            # roundtripping jsonb columns. This causes some false positives for
+            # round-tripping jsonb columns. This causes some false positives for
             # the comparison here. Therefore, we need to parse and re-dump the
             # raw value here to ensure the insignificant whitespaces are
             # consistent with our encoder's output.
-            raw_old_value = type_cast_for_database(type_cast_from_database(raw_old_value))
+            raw_old_value = serialize(deserialize(raw_old_value))
             super(raw_old_value, new_value)
           end
         end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/money.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/money.rb
index df890c2ed6..2163674019 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/money.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/money.rb
@@ -3,8 +3,6 @@ module ActiveRecord
     module PostgreSQL
       module OID # :nodoc:
         class Money < Type::Decimal # :nodoc:
-          include Infinity
-
           class_attribute :precision
 
           def type
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/point.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/point.rb
index bac8b01d6b..bf565bcf47 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/point.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/point.rb
@@ -3,19 +3,19 @@ module ActiveRecord
     module PostgreSQL
       module OID # :nodoc:
         class Point < Type::Value # :nodoc:
-          include Type::Mutable
+          include Type::Helpers::Mutable
 
           def type
             :point
           end
 
-          def type_cast(value)
+          def cast(value)
             case value
             when ::String
               if value[0] == '(' && value[-1] == ')'
                 value = value[1...-1]
               end
-              type_cast(value.split(','))
+              cast(value.split(','))
             when ::Array
               value.map { |v| Float(v) }
             else
@@ -23,7 +23,7 @@ module ActiveRecord
             end
           end
 
-          def type_cast_for_database(value)
+          def serialize(value)
             if value.is_a?(::Array)
               "(#{number_for_point(value[0])},#{number_for_point(value[1])})"
             else
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/rails_5_1_point.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/rails_5_1_point.rb
new file mode 100644
index 0000000000..7427a25ad5
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/rails_5_1_point.rb
@@ -0,0 +1,50 @@
+module ActiveRecord
+  Point = Struct.new(:x, :y)
+
+  module ConnectionAdapters
+    module PostgreSQL
+      module OID # :nodoc:
+        class Rails51Point < Type::Value # :nodoc:
+          include Type::Helpers::Mutable
+
+          def type
+            :point
+          end
+
+          def cast(value)
+            case value
+            when ::String
+              if value[0] == '(' && value[-1] == ')'
+                value = value[1...-1]
+              end
+              x, y = value.split(",")
+              build_point(x, y)
+            when ::Array
+              build_point(*value)
+            else
+              value
+            end
+          end
+
+          def serialize(value)
+            if value.is_a?(ActiveRecord::Point)
+              "(#{number_for_point(value.x)},#{number_for_point(value.y)})"
+            else
+              super
+            end
+          end
+
+          private
+
+          def number_for_point(number)
+            number.to_s.gsub(/\.0$/, '')
+          end
+
+          def build_point(x, y)
+            ActiveRecord::Point.new(Float(x), Float(y))
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/range.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/range.rb
index 3adfb8b9d8..fc201f8fb9 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/range.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/range.rb
@@ -7,7 +7,7 @@ module ActiveRecord
         class Range < Type::Value # :nodoc:
           attr_reader :subtype, :type
 
-          def initialize(subtype, type)
+          def initialize(subtype, type = :range)
             @subtype = subtype
             @type = type
           end
@@ -30,7 +30,7 @@ module ActiveRecord
             ::Range.new(from, to, extracted[:exclude_end])
           end
 
-          def type_cast_for_database(value)
+          def serialize(value)
             if value.is_a?(::Range)
               from = type_cast_single_for_database(value.begin)
               to = type_cast_single_for_database(value.end)
@@ -40,26 +40,42 @@ module ActiveRecord
             end
           end
 
+          def ==(other)
+            other.is_a?(Range) &&
+              other.subtype == subtype &&
+              other.type == type
+          end
+
           private
 
           def type_cast_single(value)
-            infinity?(value) ? value : @subtype.type_cast_from_database(value)
+            infinity?(value) ? value : @subtype.deserialize(value)
           end
 
           def type_cast_single_for_database(value)
-            infinity?(value) ? '' : @subtype.type_cast_for_database(value)
+            infinity?(value) ? '' : @subtype.serialize(value)
           end
 
           def extract_bounds(value)
             from, to = value[1..-2].split(',')
             {
-              from:          (value[1] == ',' || from == '-infinity') ? @subtype.infinity(negative: true) : from,
-              to:            (value[-2] == ',' || to == 'infinity') ? @subtype.infinity : to,
+              from:          (value[1] == ',' || from == '-infinity') ? infinity(negative: true) : from,
+              to:            (value[-2] == ',' || to == 'infinity') ? infinity : to,
               exclude_start: (value[0] == '('),
               exclude_end:   (value[-1] == ')')
             }
           end
 
+          def infinity(negative: false)
+            if subtype.respond_to?(:infinity)
+              subtype.infinity(negative: negative)
+            elsif negative
+              -::Float::INFINITY
+            else
+              ::Float::INFINITY
+            end
+          end
+
           def infinity?(value)
             value.respond_to?(:infinite?) && value.infinite?
           end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/specialized_string.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/specialized_string.rb
index b2a42e9ebb..2d2fede4e8 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/specialized_string.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/specialized_string.rb
@@ -8,10 +8,6 @@ module ActiveRecord
           def initialize(type)
             @type = type
           end
-
-          def text?
-            false
-          end
         end
       end
     end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/time.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/time.rb
deleted file mode 100644
index 8f0246eddb..0000000000
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/time.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-module ActiveRecord
-  module ConnectionAdapters
-    module PostgreSQL
-      module OID # :nodoc:
-        class Time < Type::Time # :nodoc:
-          include Infinity
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/type_map_initializer.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/type_map_initializer.rb
index 9b3de41fab..6155e53632 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/type_map_initializer.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/type_map_initializer.rb
@@ -15,11 +15,11 @@ module ActiveRecord
           def run(records)
             nodes = records.reject { |row| @store.key? row['oid'].to_i }
             mapped, nodes = nodes.partition { |row| @store.key? row['typname'] }
-            ranges, nodes = nodes.partition { |row| row['typtype'] == 'r' }
-            enums, nodes = nodes.partition { |row| row['typtype'] == 'e' }
-            domains, nodes = nodes.partition { |row| row['typtype'] == 'd' }
-            arrays, nodes = nodes.partition { |row| row['typinput'] == 'array_in' }
-            composites, nodes = nodes.partition { |row| row['typelem'] != '0' }
+            ranges, nodes = nodes.partition { |row| row['typtype'] == 'r'.freeze }
+            enums, nodes = nodes.partition { |row| row['typtype'] == 'e'.freeze }
+            domains, nodes = nodes.partition { |row| row['typtype'] == 'd'.freeze }
+            arrays, nodes = nodes.partition { |row| row['typinput'] == 'array_in'.freeze }
+            composites, nodes = nodes.partition { |row| row['typelem'].to_i != 0 }
 
             mapped.each     { |row| register_mapped_type(row)    }
             enums.each      { |row| register_enum_type(row)      }
@@ -29,6 +29,18 @@ module ActiveRecord
             composites.each { |row| register_composite_type(row) }
           end
 
+          def query_conditions_for_initial_load(type_map)
+            known_type_names = type_map.keys.map { |n| "'#{n}'" }
+            known_type_types = %w('r' 'e' 'd')
+            <<-SQL % [known_type_names.join(", "), known_type_types.join(", ")]
+              WHERE
+                t.typname IN (%s)
+                OR t.typtype IN (%s)
+                OR t.typinput = 'array_in(cstring,oid,integer)'::regprocedure
+                OR t.typelem != 0
+            SQL
+          end
+
           private
           def register_mapped_type(row)
             alias_type row['oid'], row['typname']
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/uuid.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/uuid.rb
index 97b4fd3d08..5e839228e9 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/uuid.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/uuid.rb
@@ -5,13 +5,13 @@ module ActiveRecord
         class Uuid < Type::Value # :nodoc:
           ACCEPTABLE_UUID = %r{\A\{?([a-fA-F0-9]{4}-?){8}\}?\z}x
 
-          alias_method :type_cast_for_database, :type_cast_from_database
+          alias_method :serialize, :deserialize
 
           def type
             :uuid
           end
 
-          def type_cast(value)
+          def cast(value)
             value.to_s[ACCEPTABLE_UUID, 0]
           end
         end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/vector.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/vector.rb
index de4187b028..b26e876b54 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/vector.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/vector.rb
@@ -16,7 +16,7 @@ module ActiveRecord
           # FIXME: this should probably split on +delim+ and use +subtype+
           # to cast the values.  Unfortunately, the current Rails behavior
           # is to just return the string.
-          def type_cast(value)
+          def cast(value)
             value
           end
         end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/xml.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/xml.rb
index 334af7c598..d40d837cee 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/xml.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/xml.rb
@@ -7,7 +7,7 @@ module ActiveRecord
             :xml
           end
 
-          def type_cast_for_database(value)
+          def serialize(value)
             return unless value
             Data.new(super)
           end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
index 9de9e2c7dc..d5879ea7df 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
@@ -31,6 +31,11 @@ module ActiveRecord
           Utils.extract_schema_qualified_name(name.to_s).quoted
         end
 
+        # Quotes schema names for use in SQL queries.
+        def quote_schema_name(name)
+          PGconn.quote_ident(name)
+        end
+
         def quote_table_name_for_assignment(table, attr)
           quote_column_name(attr)
         end
@@ -40,8 +45,7 @@ module ActiveRecord
           PGconn.quote_ident(name.to_s)
         end
 
-        # Quote date/time values for use in SQL input. Includes microseconds
-        # if the value is a Time responding to usec.
+        # Quote date/time values for use in SQL input.
         def quoted_date(value) #:nodoc:
           if value.year <= 0
             bce_year = format("%04d", -value.year + 1)
@@ -52,15 +56,21 @@ module ActiveRecord
         end
 
         # Does not quote function default values for UUID columns
-        def quote_default_value(value, column) #:nodoc:
+        def quote_default_expression(value, column) #:nodoc:
           if column.type == :uuid && value =~ /\(\)/
             value
-          else
-            value = column.cast_type.type_cast_for_database(value)
+          elsif column.respond_to?(:array?)
+            value = type_cast_from_column(column, value)
             quote(value)
+          else
+            super
           end
         end
 
+        def lookup_cast_type_from_column(column) # :nodoc:
+          type_map.lookup(column.oid, column.fmod, column.sql_type)
+        end
+
         private
 
         def _quote(value)
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb b/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb
index 52b307c432..44a7338bf5 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb
@@ -8,20 +8,39 @@ module ActiveRecord
 
         def disable_referential_integrity # :nodoc:
           if supports_disable_referential_integrity?
+            original_exception = nil
+
             begin
-              execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} DISABLE TRIGGER ALL" }.join(";"))
-            rescue
-              execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} DISABLE TRIGGER USER" }.join(";"))
+              transaction(requires_new: true) do
+                execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} DISABLE TRIGGER ALL" }.join(";"))
+              end
+            rescue ActiveRecord::ActiveRecordError => e
+              original_exception = e
             end
-          end
-          yield
-        ensure
-          if supports_disable_referential_integrity?
+
+            begin
+              yield
+            rescue ActiveRecord::InvalidForeignKey => e
+              warn <<-WARNING
+WARNING: Rails was not able to disable referential integrity.
+
+This is most likely caused due to missing permissions.
+Rails needs superuser privileges to disable referential integrity.
+
+    cause: #{original_exception.try(:message)}
+
+              WARNING
+              raise e
+            end
+
             begin
-              execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} ENABLE TRIGGER ALL" }.join(";"))
-            rescue
-              execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} ENABLE TRIGGER USER" }.join(";"))
+              transaction(requires_new: true) do
+                execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} ENABLE TRIGGER ALL" }.join(";"))
+              end
+            rescue ActiveRecord::ActiveRecordError
             end
+          else
+            yield
           end
         end
       end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
index a9522e152f..6399bddbee 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
@@ -2,90 +2,153 @@ module ActiveRecord
   module ConnectionAdapters
     module PostgreSQL
       module ColumnMethods
-        def xml(*args)
-          options = args.extract_options!
-          column(args[0], :xml, options)
+        # Defines the primary key field.
+        # Use of the native PostgreSQL UUID type is supported, and can be used
+        # by defining your tables as such:
+        #
+        #   create_table :stuffs, id: :uuid do |t|
+        #     t.string :content
+        #     t.timestamps
+        #   end
+        #
+        # By default, this will use the +uuid_generate_v4()+ function from the
+        # +uuid-ossp+ extension, which MUST be enabled on your database. To enable
+        # the +uuid-ossp+ extension, you can use the +enable_extension+ method in your
+        # migrations. To use a UUID primary key without +uuid-ossp+ enabled, you can
+        # set the +:default+ option to +nil+:
+        #
+        #   create_table :stuffs, id: false do |t|
+        #     t.primary_key :id, :uuid, default: nil
+        #     t.uuid :foo_id
+        #     t.timestamps
+        #   end
+        #
+        # You may also pass a different UUID generation function from +uuid-ossp+
+        # or another library.
+        #
+        # Note that setting the UUID primary key default value to +nil+ will
+        # require you to assure that you always provide a UUID value before saving
+        # a record (as primary keys cannot be +nil+). This might be done via the
+        # +SecureRandom.uuid+ method and a +before_save+ callback, for instance.
+        def primary_key(name, type = :primary_key, **options)
+          options[:default] = options.fetch(:default, 'uuid_generate_v4()') if type == :uuid
+          super
+        end
+
+        def bigserial(*args, **options)
+          args.each { |name| column(name, :bigserial, options) }
+        end
+
+        def bit(*args, **options)
+          args.each { |name| column(name, :bit, options) }
+        end
+
+        def bit_varying(*args, **options)
+          args.each { |name| column(name, :bit_varying, options) }
+        end
+
+        def cidr(*args, **options)
+          args.each { |name| column(name, :cidr, options) }
+        end
+
+        def citext(*args, **options)
+          args.each { |name| column(name, :citext, options) }
         end
 
-        def tsvector(*args)
-          options = args.extract_options!
-          column(args[0], :tsvector, options)
+        def daterange(*args, **options)
+          args.each { |name| column(name, :daterange, options) }
         end
 
-        def int4range(name, options = {})
-          column(name, :int4range, options)
+        def hstore(*args, **options)
+          args.each { |name| column(name, :hstore, options) }
         end
 
-        def int8range(name, options = {})
-          column(name, :int8range, options)
+        def inet(*args, **options)
+          args.each { |name| column(name, :inet, options) }
         end
 
-        def tsrange(name, options = {})
-          column(name, :tsrange, options)
+        def int4range(*args, **options)
+          args.each { |name| column(name, :int4range, options) }
         end
 
-        def tstzrange(name, options = {})
-          column(name, :tstzrange, options)
+        def int8range(*args, **options)
+          args.each { |name| column(name, :int8range, options) }
         end
 
-        def numrange(name, options = {})
-          column(name, :numrange, options)
+        def json(*args, **options)
+          args.each { |name| column(name, :json, options) }
         end
 
-        def daterange(name, options = {})
-          column(name, :daterange, options)
+        def jsonb(*args, **options)
+          args.each { |name| column(name, :jsonb, options) }
         end
 
-        def hstore(name, options = {})
-          column(name, :hstore, options)
+        def ltree(*args, **options)
+          args.each { |name| column(name, :ltree, options) }
         end
 
-        def ltree(name, options = {})
-          column(name, :ltree, options)
+        def macaddr(*args, **options)
+          args.each { |name| column(name, :macaddr, options) }
         end
 
-        def inet(name, options = {})
-          column(name, :inet, options)
+        def money(*args, **options)
+          args.each { |name| column(name, :money, options) }
         end
 
-        def cidr(name, options = {})
-          column(name, :cidr, options)
+        def numrange(*args, **options)
+          args.each { |name| column(name, :numrange, options) }
         end
 
-        def macaddr(name, options = {})
-          column(name, :macaddr, options)
+        def point(*args, **options)
+          args.each { |name| column(name, :point, options) }
         end
 
-        def uuid(name, options = {})
-          column(name, :uuid, options)
+        def line(*args, **options)
+          args.each { |name| column(name, :line, options) }
         end
 
-        def json(name, options = {})
-          column(name, :json, options)
+        def lseg(*args, **options)
+          args.each { |name| column(name, :lseg, options) }
         end
 
-        def jsonb(name, options = {})
-          column(name, :jsonb, options)
+        def box(*args, **options)
+          args.each { |name| column(name, :box, options) }
         end
 
-        def citext(name, options = {})
-          column(name, :citext, options)
+        def path(*args, **options)
+          args.each { |name| column(name, :path, options) }
         end
 
-        def point(name, options = {})
-          column(name, :point, options)
+        def polygon(*args, **options)
+          args.each { |name| column(name, :polygon, options) }
         end
 
-        def bit(name, options)
-          column(name, :bit, options)
+        def circle(*args, **options)
+          args.each { |name| column(name, :circle, options) }
         end
 
-        def bit_varying(name, options)
-          column(name, :bit_varying, options)
+        def serial(*args, **options)
+          args.each { |name| column(name, :serial, options) }
         end
 
-        def money(name, options)
-          column(name, :money, options)
+        def tsrange(*args, **options)
+          args.each { |name| column(name, :tsrange, options) }
+        end
+
+        def tstzrange(*args, **options)
+          args.each { |name| column(name, :tstzrange, options) }
+        end
+
+        def tsvector(*args, **options)
+          args.each { |name| column(name, :tsvector, options) }
+        end
+
+        def uuid(*args, **options)
+          args.each { |name| column(name, :uuid, options) }
+        end
+
+        def xml(*args, **options)
+          args.each { |name| column(name, :xml, options) }
         end
       end
 
@@ -96,39 +159,6 @@ module ActiveRecord
       class TableDefinition < ActiveRecord::ConnectionAdapters::TableDefinition
         include ColumnMethods
 
-        # Defines the primary key field.
-        # Use of the native PostgreSQL UUID type is supported, and can be used
-        # by defining your tables as such:
-        #
-        #   create_table :stuffs, id: :uuid do |t|
-        #     t.string :content
-        #     t.timestamps
-        #   end
-        #
-        # By default, this will use the +uuid_generate_v4()+ function from the
-        # +uuid-ossp+ extension, which MUST be enabled on your database. To enable
-        # the +uuid-ossp+ extension, you can use the +enable_extension+ method in your
-        # migrations. To use a UUID primary key without +uuid-ossp+ enabled, you can
-        # set the +:default+ option to +nil+:
-        #
-        #   create_table :stuffs, id: false do |t|
-        #     t.primary_key :id, :uuid, default: nil
-        #     t.uuid :foo_id
-        #     t.timestamps
-        #   end
-        #
-        # You may also pass a different UUID generation function from +uuid-ossp+
-        # or another library.
-        #
-        # Note that setting the UUID primary key default value to +nil+ will
-        # require you to assure that you always provide a UUID value before saving
-        # a record (as primary keys cannot be +nil+). This might be done via the
-        # +SecureRandom.uuid+ method and a +before_save+ callback, for instance.
-        def primary_key(name, type = :primary_key, options = {})
-          options[:default] = options.fetch(:default, 'uuid_generate_v4()') if type == :uuid
-          super
-        end
-
         def new_column_definition(name, type, options) # :nodoc:
           column = super
           column.array = options[:array]
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb
new file mode 100644
index 0000000000..a4f0742516
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb
@@ -0,0 +1,54 @@
+module ActiveRecord
+  module ConnectionAdapters
+    module PostgreSQL
+      module ColumnDumper
+        def column_spec_for_primary_key(column)
+          spec = {}
+          if column.serial?
+            return unless column.bigint?
+            spec[:id] = ':bigserial'
+          elsif column.type == :uuid
+            spec[:id] = ':uuid'
+            spec[:default] = column.default_function.inspect
+          else
+            spec[:id] = column.type.inspect
+            spec.merge!(prepare_column_options(column).delete_if { |key, _| [:name, :type, :null].include?(key) })
+          end
+          spec
+        end
+
+        # Adds +:array+ option to the default set
+        def prepare_column_options(column)
+          spec = super
+          spec[:array] = 'true' if column.array?
+          spec
+        end
+
+        # Adds +:array+ as a valid migration key
+        def migration_keys
+          super + [:array]
+        end
+
+        private
+
+        def schema_type(column)
+          return super unless column.serial?
+
+          if column.bigint?
+            'bigserial'
+          else
+            'serial'
+          end
+        end
+
+        def schema_default(column)
+          if column.default_function
+            column.default_function.inspect unless column.serial?
+          else
+            super
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index a90adcf4aa..aaf5b2898b 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -4,34 +4,17 @@ module ActiveRecord
       class SchemaCreation < AbstractAdapter::SchemaCreation
         private
 
-        def column_options(o)
-          column_options = super
-          column_options[:array] = o.array
-          column_options
+        def visit_ColumnDefinition(o)
+          o.sql_type = type_to_sql(o.type, o.limit, o.precision, o.scale, o.array)
+          super
         end
 
         def add_column_options!(sql, options)
-          if options[:array]
-            sql << '[]'
+          if options[:collation]
+            sql << " COLLATE \"#{options[:collation]}\""
           end
           super
         end
-
-        def quote_default_expression(value, column)
-          if column.type == :uuid && value =~ /\(\)/
-            value
-          else
-            super
-          end
-        end
-
-        def type_for_column(column)
-          if column.array
-            @conn.lookup_cast_type("#{column.sql_type}[]")
-          else
-            super
-          end
-        end
       end
 
       module SchemaStatements
@@ -85,12 +68,18 @@ module ActiveRecord
           execute "DROP DATABASE IF EXISTS #{quote_table_name(name)}"
         end
 
-        # Returns the list of all tables in the schema search path or a specified schema.
+        # Returns the list of all tables in the schema search path.
         def tables(name = nil)
-          query(<<-SQL, 'SCHEMA').map { |row| row[0] }
-            SELECT tablename
-            FROM pg_tables
-            WHERE schemaname = ANY (current_schemas(false))
+          select_values("SELECT tablename FROM pg_tables WHERE schemaname = ANY(current_schemas(false))", 'SCHEMA')
+        end
+
+        def data_sources # :nodoc
+          select_values(<<-SQL, 'SCHEMA')
+            SELECT c.relname
+            FROM pg_class c
+            LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
+            WHERE c.relkind IN ('r', 'v','m') -- (r)elation/table, (v)iew, (m)aterialized view
+            AND n.nspname = ANY (current_schemas(false))
           SQL
         end
 
@@ -101,7 +90,7 @@ module ActiveRecord
           name = Utils.extract_schema_qualified_name(name.to_s)
           return false unless name.identifier
 
-          exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
+          select_value(<<-SQL, 'SCHEMA').to_i > 0
               SELECT COUNT(*)
               FROM pg_class c
               LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
@@ -110,30 +99,56 @@ module ActiveRecord
               AND n.nspname = #{name.schema ? "'#{name.schema}'" : 'ANY (current_schemas(false))'}
           SQL
         end
+        alias data_source_exists? table_exists?
 
-        def drop_table(table_name, options = {})
-          execute "DROP TABLE #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
+        def views # :nodoc:
+          select_values(<<-SQL, 'SCHEMA')
+            SELECT c.relname
+            FROM pg_class c
+            LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
+            WHERE c.relkind IN ('v','m') -- (v)iew, (m)aterialized view
+            AND n.nspname = ANY (current_schemas(false))
+          SQL
+        end
+
+        def view_exists?(view_name) # :nodoc:
+          name = Utils.extract_schema_qualified_name(view_name.to_s)
+          return false unless name.identifier
+
+          select_values(<<-SQL, 'SCHEMA').any?
+            SELECT c.relname
+            FROM pg_class c
+            LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
+            WHERE c.relkind IN ('v','m') -- (v)iew, (m)aterialized view
+            AND c.relname = '#{name.identifier}'
+            AND n.nspname = #{name.schema ? "'#{name.schema}'" : 'ANY (current_schemas(false))'}
+          SQL
+        end
+
+        def drop_table(table_name, options = {}) # :nodoc:
+          execute "DROP TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
         end
 
         # Returns true if schema exists.
         def schema_exists?(name)
-          exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
-            SELECT COUNT(*)
-            FROM pg_namespace
-            WHERE nspname = '#{name}'
-          SQL
+          select_value("SELECT COUNT(*) FROM pg_namespace WHERE nspname = '#{name}'", 'SCHEMA').to_i > 0
         end
 
+        # Verifies existence of an index with a given name.
         def index_name_exists?(table_name, index_name, default)
-          exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
+          table = Utils.extract_schema_qualified_name(table_name.to_s)
+          index = Utils.extract_schema_qualified_name(index_name.to_s)
+
+          select_value(<<-SQL, 'SCHEMA').to_i > 0
             SELECT COUNT(*)
             FROM pg_class t
             INNER JOIN pg_index d ON t.oid = d.indrelid
             INNER JOIN pg_class i ON d.indexrelid = i.oid
+            LEFT JOIN pg_namespace n ON n.oid = i.relnamespace
             WHERE i.relkind = 'i'
-              AND i.relname = '#{index_name}'
-              AND t.relname = '#{table_name}'
-              AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (current_schemas(false)) )
+              AND i.relname = '#{index.identifier}'
+              AND t.relname = '#{table.identifier}'
+              AND n.nspname = #{index.schema ? "'#{index.schema}'" : 'ANY (current_schemas(false))'}
           SQL
         end
 
@@ -153,8 +168,8 @@ module ActiveRecord
 
           result.map do |row|
             index_name = row[0]
-            unique = row[1] == 't'
-            indkey = row[2].split(" ")
+            unique = row[1]
+            indkey = row[2].split(" ").map(&:to_i)
             inddef = row[3]
             oid = row[4]
 
@@ -182,53 +197,48 @@ module ActiveRecord
         # Returns the list of all column definitions for a table.
         def columns(table_name)
           # Limit, precision, and scale are all handled by the superclass.
-          column_definitions(table_name).map do |column_name, type, default, notnull, oid, fmod|
-            oid = get_oid_type(oid.to_i, fmod.to_i, column_name, type)
-            default_value = extract_value_from_default(oid, default)
+          column_definitions(table_name).map do |column_name, type, default, notnull, oid, fmod, collation|
+            oid = oid.to_i
+            fmod = fmod.to_i
+            type_metadata = fetch_type_metadata(column_name, type, oid, fmod)
+            default_value = extract_value_from_default(default)
             default_function = extract_default_function(default_value, default)
-            new_column(column_name, default_value, oid, type, notnull == 'f', default_function)
+            new_column(column_name, default_value, type_metadata, !notnull, default_function, collation)
           end
         end
 
-        def new_column(name, default, cast_type, sql_type = nil, null = true, default_function = nil) # :nodoc:
-          PostgreSQLColumn.new(name, default, cast_type, sql_type, null, default_function)
+        def new_column(name, default, sql_type_metadata = nil, null = true, default_function = nil, collation = nil) # :nodoc:
+          PostgreSQLColumn.new(name, default, sql_type_metadata, null, default_function, collation)
         end
 
         # Returns the current database name.
         def current_database
-          query('select current_database()', 'SCHEMA')[0][0]
+          select_value('select current_database()', 'SCHEMA')
         end
 
         # Returns the current schema name.
         def current_schema
-          query('SELECT current_schema', 'SCHEMA')[0][0]
+          select_value('SELECT current_schema', 'SCHEMA')
         end
 
         # Returns the current database encoding format.
         def encoding
-          query(<<-end_sql, 'SCHEMA')[0][0]
-            SELECT pg_encoding_to_char(pg_database.encoding) FROM pg_database
-            WHERE pg_database.datname LIKE '#{current_database}'
-          end_sql
+          select_value("SELECT pg_encoding_to_char(encoding) FROM pg_database WHERE datname LIKE '#{current_database}'", 'SCHEMA')
         end
 
         # Returns the current database collation.
         def collation
-          query(<<-end_sql, 'SCHEMA')[0][0]
-            SELECT pg_database.datcollate FROM pg_database WHERE pg_database.datname LIKE '#{current_database}'
-          end_sql
+          select_value("SELECT datcollate FROM pg_database WHERE datname LIKE '#{current_database}'", 'SCHEMA')
         end
 
         # Returns the current database ctype.
         def ctype
-          query(<<-end_sql, 'SCHEMA')[0][0]
-            SELECT pg_database.datctype FROM pg_database WHERE pg_database.datname LIKE '#{current_database}'
-          end_sql
+          select_value("SELECT datctype FROM pg_database WHERE datname LIKE '#{current_database}'", 'SCHEMA')
         end
 
         # Returns an array of schema names.
         def schema_names
-          query(<<-SQL, 'SCHEMA').flatten
+          select_values(<<-SQL, 'SCHEMA')
             SELECT nspname
               FROM pg_namespace
              WHERE nspname !~ '^pg_.*'
@@ -239,12 +249,12 @@ module ActiveRecord
 
         # Creates a schema for the given schema name.
         def create_schema schema_name
-          execute "CREATE SCHEMA #{schema_name}"
+          execute "CREATE SCHEMA #{quote_schema_name(schema_name)}"
         end
 
         # Drops the schema for the given schema name.
-        def drop_schema schema_name
-          execute "DROP SCHEMA #{schema_name} CASCADE"
+        def drop_schema(schema_name, options = {})
+          execute "DROP SCHEMA#{' IF EXISTS' if options[:if_exists]} #{quote_schema_name(schema_name)} CASCADE"
         end
 
         # Sets the schema search path to a string of comma-separated schema names.
@@ -261,12 +271,12 @@ module ActiveRecord
 
         # Returns the active schema search path.
         def schema_search_path
-          @schema_search_path ||= query('SHOW search_path', 'SCHEMA')[0][0]
+          @schema_search_path ||= select_value('SHOW search_path', 'SCHEMA')
         end
 
         # Returns the current client message level.
         def client_min_messages
-          query('SHOW client_min_messages', 'SCHEMA')[0][0]
+          select_value('SHOW client_min_messages', 'SCHEMA')
         end
 
         # Set the client message level.
@@ -284,10 +294,7 @@ module ActiveRecord
         end
 
         def serial_sequence(table, column)
-          result = exec_query(<<-eosql, 'SCHEMA')
-            SELECT pg_get_serial_sequence('#{table}', '#{column}')
-          eosql
-          result.rows.first.first
+          select_value("SELECT pg_get_serial_sequence('#{table}', '#{column}')", 'SCHEMA')
         end
 
         # Sets the sequence of a table's primary key to the specified value.
@@ -298,9 +305,7 @@ module ActiveRecord
             if sequence
               quoted_sequence = quote_table_name(sequence)
 
-              select_value <<-end_sql, 'SCHEMA'
-              SELECT setval('#{quoted_sequence}', #{value})
-              end_sql
+              select_value("SELECT setval('#{quoted_sequence}', #{value})", 'SCHEMA')
             else
               @logger.warn "#{table} has primary key #{pk} with no default sequence" if @logger
             end
@@ -323,7 +328,7 @@ module ActiveRecord
           if pk && sequence
             quoted_sequence = quote_table_name(sequence)
 
-            select_value <<-end_sql, 'SCHEMA'
+            select_value(<<-end_sql, 'SCHEMA')
               SELECT setval('#{quoted_sequence}', (SELECT COALESCE(MAX(#{quote_column_name pk})+(SELECT increment_by FROM #{quoted_sequence}), (SELECT min_value FROM #{quoted_sequence})) FROM #{quote_table_name(table)}), false)
             end_sql
           end
@@ -383,17 +388,19 @@ module ActiveRecord
           nil
         end
 
-        # Returns just a table's primary key
-        def primary_key(table)
-          pks = exec_query(<<-end_sql, 'SCHEMA').rows
-            SELECT attr.attname
-            FROM pg_attribute attr
-            INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = any(cons.conkey)
-            WHERE cons.contype = 'p'
-              AND cons.conrelid = '#{quote_table_name(table)}'::regclass
-          end_sql
-          return nil unless pks.count == 1
-          pks[0][0]
+        def primary_keys(table_name) # :nodoc:
+          select_values(<<-SQL.strip_heredoc, 'SCHEMA')
+            WITH pk_constraint AS (
+              SELECT conrelid, unnest(conkey) AS connum FROM pg_constraint
+              WHERE contype = 'p'
+                AND conrelid = '#{quote_table_name(table_name)}'::regclass
+            ), cons AS (
+              SELECT conrelid, connum, row_number() OVER() AS rownum FROM pk_constraint
+            )
+            SELECT attr.attname FROM pg_attribute attr
+            INNER JOIN cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.connum
+            ORDER BY cons.rownum
+          SQL
         end
 
         # Renames a table.
@@ -410,30 +417,32 @@ module ActiveRecord
             new_seq = "#{new_name}_#{pk}_seq"
             idx = "#{table_name}_pkey"
             new_idx = "#{new_name}_pkey"
-            execute "ALTER TABLE #{quote_table_name(seq)} RENAME TO #{quote_table_name(new_seq)}"
+            execute "ALTER TABLE #{seq.quoted} RENAME TO #{quote_table_name(new_seq)}"
             execute "ALTER INDEX #{quote_table_name(idx)} RENAME TO #{quote_table_name(new_idx)}"
           end
 
           rename_table_indexes(table_name, new_name)
         end
 
-        # Adds a new column to the named table.
-        # See TableDefinition#column for details of the options you can use.
-        def add_column(table_name, column_name, type, options = {})
+        def add_column(table_name, column_name, type, options = {}) #:nodoc:
           clear_cache!
           super
         end
 
-        # Changes the column of a table.
-        def change_column(table_name, column_name, type, options = {})
+        def change_column(table_name, column_name, type, options = {}) #:nodoc:
           clear_cache!
           quoted_table_name = quote_table_name(table_name)
-          sql_type = type_to_sql(type, options[:limit], options[:precision], options[:scale])
-          sql_type << "[]" if options[:array]
-          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{sql_type}"
-          sql << " USING #{options[:using]}" if options[:using]
-          if options[:cast_as]
-            sql << " USING CAST(#{quote_column_name(column_name)} AS #{type_to_sql(options[:cast_as], options[:limit], options[:precision], options[:scale])})"
+          quoted_column_name = quote_column_name(column_name)
+          sql_type = type_to_sql(type, options[:limit], options[:precision], options[:scale], options[:array])
+          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}"
+          if options[:collation]
+            sql << " COLLATE \"#{options[:collation]}\""
+          end
+          if options[:using]
+            sql << " USING #{options[:using]}"
+          elsif options[:cast_as]
+            cast_as_type = type_to_sql(options[:cast_as], options[:limit], options[:precision], options[:scale], options[:array])
+            sql << " USING CAST(#{quoted_column_name} AS #{cast_as_type})"
           end
           execute sql
 
@@ -442,32 +451,33 @@ module ActiveRecord
         end
 
         # Changes the default value of a table column.
-        def change_column_default(table_name, column_name, default)
+        def change_column_default(table_name, column_name, default_or_changes) # :nodoc:
           clear_cache!
           column = column_for(table_name, column_name)
           return unless column
 
+          default = extract_new_default_value(default_or_changes)
           alter_column_query = "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} %s"
           if default.nil?
             # <tt>DEFAULT NULL</tt> results in the same behavior as <tt>DROP DEFAULT</tt>. However, PostgreSQL will
             # cast the default to the columns type, which leaves us with a default like "default NULL::character varying".
             execute alter_column_query % "DROP DEFAULT"
           else
-            execute alter_column_query % "SET DEFAULT #{quote_default_value(default, column)}"
+            execute alter_column_query % "SET DEFAULT #{quote_default_expression(default, column)}"
           end
         end
 
-        def change_column_null(table_name, column_name, null, default = nil)
+        def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
           clear_cache!
           unless null || default.nil?
             column = column_for(table_name, column_name)
-            execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote_default_value(default, column)} WHERE #{quote_column_name(column_name)} IS NULL") if column
+            execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote_default_expression(default, column)} WHERE #{quote_column_name(column_name)} IS NULL") if column
           end
           execute("ALTER TABLE #{quote_table_name(table_name)} ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL")
         end
 
         # Renames a column in a table.
-        def rename_column(table_name, column_name, new_column_name)
+        def rename_column(table_name, column_name, new_column_name) #:nodoc:
           clear_cache!
           execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
           rename_column_indexes(table_name, column_name, new_column_name)
@@ -478,10 +488,19 @@ module ActiveRecord
           execute "CREATE #{index_type} INDEX #{index_algorithm} #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} #{index_using} (#{index_columns})#{index_options}"
         end
 
-        def remove_index!(table_name, index_name) #:nodoc:
-          execute "DROP INDEX #{quote_table_name(index_name)}"
+        def remove_index(table_name, options = {}) #:nodoc:
+          index_name = index_name_for_remove(table_name, options)
+          algorithm =
+            if Hash === options && options.key?(:algorithm)
+              index_algorithms.fetch(options[:algorithm]) do
+                raise ArgumentError.new("Algorithm must be one of the following: #{index_algorithms.keys.map(&:inspect).join(', ')}")
+              end
+            end
+          execute "DROP INDEX #{algorithm} #{quote_table_name(index_name)}"
         end
 
+        # Renames an index of a table. Raises error if length of new
+        # index name is greater than allowed limit.
         def rename_index(table_name, old_name, new_name)
           validate_index_length!(table_name, new_name)
 
@@ -530,41 +549,35 @@ module ActiveRecord
         end
 
         # Maps logical Rails types to PostgreSQL-specific data types.
-        def type_to_sql(type, limit = nil, precision = nil, scale = nil)
-          case type.to_s
+        def type_to_sql(type, limit = nil, precision = nil, scale = nil, array = nil)
+          sql = case type.to_s
           when 'binary'
             # PostgreSQL doesn't support limits on binary (bytea) columns.
-            # The hard limit is 1Gb, because of a 32-bit size field, and TOAST.
+            # The hard limit is 1GB, because of a 32-bit size field, and TOAST.
             case limit
             when nil, 0..0x3fffffff; super(type)
             else raise(ActiveRecordError, "No binary type has byte size #{limit}.")
             end
           when 'text'
             # PostgreSQL doesn't support limits on text columns.
-            # The hard limit is 1Gb, according to section 8.3 in the manual.
+            # The hard limit is 1GB, according to section 8.3 in the manual.
             case limit
             when nil, 0..0x3fffffff; super(type)
             else raise(ActiveRecordError, "The limit on text can be at most 1GB - 1byte.")
             end
           when 'integer'
-            return 'integer' unless limit
-
             case limit
-              when 1, 2; 'smallint'
-              when 3, 4; 'integer'
-              when 5..8; 'bigint'
-              else raise(ActiveRecordError, "No integer type has byte size #{limit}. Use a numeric with precision 0 instead.")
-            end
-          when 'datetime'
-            return super unless precision
-
-            case precision
-              when 0..6; "timestamp(#{precision})"
-              else raise(ActiveRecordError, "No timestamp type has precision of #{precision}. The allowed range of precision is from 0 to 6")
+            when 1, 2; 'smallint'
+            when nil, 3, 4; 'integer'
+            when 5..8; 'bigint'
+            else raise(ActiveRecordError, "No integer type has byte size #{limit}. Use a numeric with precision 0 instead.")
             end
           else
-            super
+            super(type, limit, precision, scale)
           end
+
+          sql << '[]' if array && type != :primary_key
+          sql
         end
 
         # PostgreSQL requires the ORDER BY columns in the select list for distinct queries, and
@@ -580,6 +593,18 @@ module ActiveRecord
 
           [super, *order_columns].join(', ')
         end
+
+        def fetch_type_metadata(column_name, sql_type, oid, fmod)
+          cast_type = get_oid_type(oid, fmod, column_name, sql_type)
+          simple_type = SqlTypeMetadata.new(
+            sql_type: sql_type,
+            type: cast_type.type,
+            limit: cast_type.limit,
+            precision: cast_type.precision,
+            scale: cast_type.scale,
+          )
+          PostgreSQLTypeMetadata.new(simple_type, oid: oid, fmod: fmod)
+        end
       end
     end
   end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/type_metadata.rb b/activerecord/lib/active_record/connection_adapters/postgresql/type_metadata.rb
new file mode 100644
index 0000000000..b2c49989a4
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/type_metadata.rb
@@ -0,0 +1,35 @@
+module ActiveRecord
+  module ConnectionAdapters
+    class PostgreSQLTypeMetadata < DelegateClass(SqlTypeMetadata)
+      attr_reader :oid, :fmod, :array
+
+      def initialize(type_metadata, oid: nil, fmod: nil)
+        super(type_metadata)
+        @type_metadata = type_metadata
+        @oid = oid
+        @fmod = fmod
+        @array = /\[\]$/ === type_metadata.sql_type
+      end
+
+      def sql_type
+        super.gsub(/\[\]$/, "".freeze)
+      end
+
+      def ==(other)
+        other.is_a?(PostgreSQLTypeMetadata) &&
+          attributes_for_hash == other.attributes_for_hash
+      end
+      alias eql? ==
+
+      def hash
+        attributes_for_hash.hash
+      end
+
+      protected
+
+      def attributes_for_hash
+        [self.class, @type_metadata, oid, fmod]
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index f4f9747359..236c067fd5 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -1,21 +1,20 @@
-require 'active_record/connection_adapters/abstract_adapter'
-require 'active_record/connection_adapters/statement_pool'
-
-require 'active_record/connection_adapters/postgresql/utils'
-require 'active_record/connection_adapters/postgresql/column'
-require 'active_record/connection_adapters/postgresql/oid'
-require 'active_record/connection_adapters/postgresql/quoting'
-require 'active_record/connection_adapters/postgresql/referential_integrity'
-require 'active_record/connection_adapters/postgresql/schema_definitions'
-require 'active_record/connection_adapters/postgresql/schema_statements'
-require 'active_record/connection_adapters/postgresql/database_statements'
-
-require 'arel/visitors/bind_visitor'
-
-# Make sure we're using pg high enough for PGResult#values
-gem 'pg', '~> 0.15'
+# Make sure we're using pg high enough for type casts and Ruby 2.2+ compatibility
+gem 'pg', '~> 0.18'
 require 'pg'
 
+require "active_record/connection_adapters/abstract_adapter"
+require "active_record/connection_adapters/postgresql/column"
+require "active_record/connection_adapters/postgresql/database_statements"
+require "active_record/connection_adapters/postgresql/oid"
+require "active_record/connection_adapters/postgresql/quoting"
+require "active_record/connection_adapters/postgresql/referential_integrity"
+require "active_record/connection_adapters/postgresql/schema_definitions"
+require "active_record/connection_adapters/postgresql/schema_dumper"
+require "active_record/connection_adapters/postgresql/schema_statements"
+require "active_record/connection_adapters/postgresql/type_metadata"
+require "active_record/connection_adapters/postgresql/utils"
+require "active_record/connection_adapters/statement_pool"
+
 require 'ipaddr'
 
 module ActiveRecord
@@ -68,11 +67,11 @@ module ActiveRecord
     #   defaults to true.
     #
     # Any further options are used as connection parameters to libpq. See
-    # http://www.postgresql.org/docs/9.1/static/libpq-connect.html for the
+    # http://www.postgresql.org/docs/current/static/libpq-connect.html for the
     # list of parameters.
     #
     # In addition, default connection parameters of libpq can be set per environment variables.
-    # See http://www.postgresql.org/docs/9.1/static/libpq-envars.html .
+    # See http://www.postgresql.org/docs/current/static/libpq-envars.html .
     class PostgreSQLAdapter < AbstractAdapter
       ADAPTER_NAME = 'PostgreSQL'.freeze
 
@@ -119,42 +118,14 @@ module ActiveRecord
       include PostgreSQL::ReferentialIntegrity
       include PostgreSQL::SchemaStatements
       include PostgreSQL::DatabaseStatements
+      include PostgreSQL::ColumnDumper
       include Savepoints
 
       def schema_creation # :nodoc:
         PostgreSQL::SchemaCreation.new self
       end
 
-      def column_spec_for_primary_key(column)
-        spec = {}
-        if column.serial?
-          return unless column.sql_type == 'bigint'
-          spec[:id] = ':bigserial'
-        elsif column.type == :uuid
-          spec[:id] = ':uuid'
-          spec[:default] = column.default_function.inspect
-        else
-          spec[:id] = column.type.inspect
-          spec.merge!(prepare_column_options(column).delete_if { |key, _| [:name, :type, :null].include?(key) })
-        end
-        spec
-      end
-
-      # Adds +:array+ option to the default set provided by the
-      # AbstractAdapter
-      def prepare_column_options(column) # :nodoc:
-        spec = super
-        spec[:array] = 'true' if column.array?
-        spec[:default] = "\"#{column.default_function}\"" if column.default_function
-        spec
-      end
-
-      # Adds +:array+ as a valid migration key
-      def migration_keys
-        super + [:array]
-      end
-
-      # Returns +true+, since this connection adapter supports prepared statement
+      # Returns true, since this connection adapter supports prepared statement
       # caching.
       def supports_statement_cache?
         true
@@ -180,52 +151,35 @@ module ActiveRecord
         true
       end
 
+      def supports_datetime_with_precision?
+        true
+      end
+
+      def supports_json?
+        postgresql_version >= 90200
+      end
+
       def index_algorithms
         { concurrently: 'CONCURRENTLY' }
       end
 
       class StatementPool < ConnectionAdapters::StatementPool
         def initialize(connection, max)
-          super
+          super(max)
+          @connection = connection
           @counter = 0
-          @cache   = Hash.new { |h,pid| h[pid] = {} }
         end
 
-        def each(&block); cache.each(&block); end
-        def key?(key);    cache.key?(key); end
-        def [](key);      cache[key]; end
-        def length;       cache.length; end
-
         def next_key
           "a#{@counter + 1}"
         end
 
         def []=(sql, key)
-          while @max <= cache.size
-            dealloc(cache.shift.last)
-          end
-          @counter += 1
-          cache[sql] = key
-        end
-
-        def clear
-          cache.each_value do |stmt_key|
-            dealloc stmt_key
-          end
-          cache.clear
-        end
-
-        def delete(sql_key)
-          dealloc cache[sql_key]
-          cache.delete sql_key
+          super.tap { @counter += 1 }
         end
 
         private
 
-          def cache
-            @cache[Process.pid]
-          end
-
           def dealloc(key)
             @connection.query "DEALLOCATE #{key}" if connection_active?
           end
@@ -244,6 +198,7 @@ module ActiveRecord
         @visitor = Arel::Visitors::PostgreSQL.new self
         if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
           @prepared_statements = true
+          @visitor.extend(DetermineIfPreparableVisitor)
         else
           @prepared_statements = false
         end
@@ -255,6 +210,7 @@ module ActiveRecord
         @table_alias_length = nil
 
         connect
+        add_pg_encoders
         @statements = StatementPool.new @connection,
                                         self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 })
 
@@ -262,6 +218,8 @@ module ActiveRecord
           raise "Your version of PostgreSQL (#{postgresql_version}) is too old, please upgrade!"
         end
 
+        add_pg_decoders
+
         @type_map = Type::HashLookupTypeMap.new
         initialize_type_map(type_map)
         @local_tz = execute('SHOW TIME ZONE', 'SCHEMA').first["TimeZone"]
@@ -426,7 +384,7 @@ module ActiveRecord
           @connection.server_version
         end
 
-        # See http://www.postgresql.org/docs/9.1/static/errcodes-appendix.html
+        # See http://www.postgresql.org/docs/current/static/errcodes-appendix.html
         FOREIGN_KEY_VIOLATION = "23503"
         UNIQUE_VIOLATION      = "23505"
 
@@ -459,11 +417,11 @@ module ActiveRecord
         end
 
         def initialize_type_map(m) # :nodoc:
-          register_class_with_limit m, 'int2', OID::Integer
-          register_class_with_limit m, 'int4', OID::Integer
-          register_class_with_limit m, 'int8', OID::Integer
+          register_class_with_limit m, 'int2', Type::Integer
+          register_class_with_limit m, 'int4', Type::Integer
+          register_class_with_limit m, 'int8', Type::Integer
           m.alias_type 'oid', 'int2'
-          m.register_type 'float4', OID::Float.new
+          m.register_type 'float4', Type::Float.new
           m.alias_type 'float8', 'float4'
           m.register_type 'text', Type::Text.new
           register_class_with_limit m, 'varchar', Type::String
@@ -474,8 +432,7 @@ module ActiveRecord
           register_class_with_limit m, 'bit', OID::Bit
           register_class_with_limit m, 'varbit', OID::BitVarying
           m.alias_type 'timestamptz', 'timestamp'
-          m.register_type 'date', OID::Date.new
-          m.register_type 'time', OID::Time.new
+          m.register_type 'date', Type::Date.new
 
           m.register_type 'money', OID::Money.new
           m.register_type 'bytea', OID::Bytea.new
@@ -501,10 +458,8 @@ module ActiveRecord
           m.alias_type 'lseg', 'varchar'
           m.alias_type 'box', 'varchar'
 
-          m.register_type 'timestamp' do |_, _, sql_type|
-            precision = extract_precision(sql_type)
-            OID::DateTime.new(precision: precision)
-          end
+          register_class_with_precision m, 'time', Type::Time
+          register_class_with_precision m, 'timestamp', OID::DateTime
 
           m.register_type 'numeric' do |_, fmod, sql_type|
             precision = extract_precision(sql_type)
@@ -541,13 +496,13 @@ module ActiveRecord
         end
 
         # Extracts the value from a PostgreSQL column default definition.
-        def extract_value_from_default(oid, default) # :nodoc:
+        def extract_value_from_default(default) # :nodoc:
           case default
             # Quoted types
             when /\A[\(B]?'(.*)'::/m
-              $1.gsub(/''/, "'")
+              $1.gsub("''".freeze, "'".freeze)
             # Boolean types
-            when 'true', 'false'
+            when 'true'.freeze, 'false'.freeze
               default
             # Numeric types
             when /\A\(?(-?\d+(\.\d*)?)\)?(::bigint)?\z/
@@ -571,6 +526,8 @@ module ActiveRecord
         end
 
         def load_additional_types(type_map, oids = nil) # :nodoc:
+          initializer = OID::TypeMapInitializer.new(type_map)
+
           if supports_ranges?
             query = <<-SQL
               SELECT t.oid, t.typname, t.typelem, t.typdelim, t.typinput, r.rngsubtype, t.typtype, t.typbasetype
@@ -586,35 +543,41 @@ module ActiveRecord
 
           if oids
             query += "WHERE t.oid::integer IN (%s)" % oids.join(", ")
+          else
+            query += initializer.query_conditions_for_initial_load(type_map)
           end
 
-          initializer = OID::TypeMapInitializer.new(type_map)
-          records = execute(query, 'SCHEMA')
-          initializer.run(records)
+          execute_and_clear(query, 'SCHEMA', []) do |records|
+            initializer.run(records)
+          end
         end
 
         FEATURE_NOT_SUPPORTED = "0A000" #:nodoc:
 
-        def execute_and_clear(sql, name, binds)
-          result = without_prepared_statement?(binds) ? exec_no_cache(sql, name, binds) :
-                                                        exec_cache(sql, name, binds)
+        def execute_and_clear(sql, name, binds, prepare: false)
+          if without_prepared_statement?(binds)
+            result = exec_no_cache(sql, name, [])
+          elsif !prepare
+            result = exec_no_cache(sql, name, binds)
+          else
+            result = exec_cache(sql, name, binds)
+          end
           ret = yield result
           result.clear
           ret
         end
 
         def exec_no_cache(sql, name, binds)
-          log(sql, name, binds) { @connection.async_exec(sql, []) }
+          type_casted_binds = binds.map { |attr| type_cast(attr.value_for_database) }
+          log(sql, name, binds) { @connection.async_exec(sql, type_casted_binds) }
         end
 
         def exec_cache(sql, name, binds)
           stmt_key = prepare_statement(sql)
-          type_casted_binds = binds.map { |col, val|
-            [col, type_cast(val, col)]
-          }
+          type_casted_binds = binds.map { |attr| type_cast(attr.value_for_database) }
 
-          log(sql, name, type_casted_binds, stmt_key) do
-            @connection.exec_prepared(stmt_key, type_casted_binds.map { |_, val| val })
+          log(sql, name, binds, stmt_key) do
+            @connection.exec_prepared(stmt_key, type_casted_binds)
           end
         rescue ActiveRecord::StatementInvalid => e
           pgerror = e.original_exception
@@ -701,7 +664,7 @@ module ActiveRecord
           end
 
           # SET statements from :variables config hash
-          # http://www.postgresql.org/docs/8.3/static/sql-set.html
+          # http://www.postgresql.org/docs/current/static/sql-set.html
           variables = @config[:variables] || {}
           variables.map do |k, v|
             if v == ':default' || v == :default
@@ -745,9 +708,11 @@ module ActiveRecord
         #  - format_type includes the column size constraint, e.g. varchar(50)
         #  - ::regclass is a function that gives the id for a table name
         def column_definitions(table_name) # :nodoc:
-          exec_query(<<-end_sql, 'SCHEMA').rows
+          query(<<-end_sql, 'SCHEMA')
               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
-                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
+                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod,
+             (SELECT c.collname FROM pg_collation c, pg_type t
+               WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation)
                 FROM pg_attribute a LEFT JOIN pg_attrdef d
                   ON a.attrelid = d.adrelid AND a.attnum = d.adnum
                WHERE a.attrelid = '#{quote_table_name(table_name)}'::regclass
@@ -757,13 +722,93 @@ module ActiveRecord
         end
 
         def extract_table_ref_from_insert_sql(sql) # :nodoc:
-          sql[/into\s+([^\(]*).*values\s*\(/im]
+          sql[/into\s("[A-Za-z0-9_."\[\]\s]+"|[A-Za-z0-9_."\[\]]+)\s*/im]
           $1.strip if $1
         end
 
         def create_table_definition(name, temporary = false, options = nil, as = nil) # :nodoc:
           PostgreSQL::TableDefinition.new native_database_types, name, temporary, options, as
         end
+
+        def can_perform_case_insensitive_comparison_for?(column)
+          @case_insensitive_cache ||= {}
+          @case_insensitive_cache[column.sql_type] ||= begin
+            sql = <<-end_sql
+              SELECT exists(
+                SELECT * FROM pg_proc
+                INNER JOIN pg_cast
+                  ON casttarget::text::oidvector = proargtypes
+                WHERE proname = 'lower'
+                  AND castsource = '#{column.sql_type}'::regtype::oid
+              )
+            end_sql
+            execute_and_clear(sql, "SCHEMA", []) do |result|
+              result.getvalue(0, 0)
+            end
+          end
+        end
+
+        def add_pg_encoders
+          map = PG::TypeMapByClass.new
+          map[Integer] = PG::TextEncoder::Integer.new
+          map[TrueClass] = PG::TextEncoder::Boolean.new
+          map[FalseClass] = PG::TextEncoder::Boolean.new
+          map[Float] = PG::TextEncoder::Float.new
+          @connection.type_map_for_queries = map
+        end
+
+        def add_pg_decoders
+          coders_by_name = {
+            'int2' => PG::TextDecoder::Integer,
+            'int4' => PG::TextDecoder::Integer,
+            'int8' => PG::TextDecoder::Integer,
+            'oid' => PG::TextDecoder::Integer,
+            'float4' => PG::TextDecoder::Float,
+            'float8' => PG::TextDecoder::Float,
+            'bool' => PG::TextDecoder::Boolean,
+          }
+          known_coder_types = coders_by_name.keys.map { |n| quote(n) }
+          query = <<-SQL % known_coder_types.join(", ")
+            SELECT t.oid, t.typname
+            FROM pg_type as t
+            WHERE t.typname IN (%s)
+          SQL
+          coders = execute_and_clear(query, "SCHEMA", []) do |result|
+            result
+              .map { |row| construct_coder(row, coders_by_name[row['typname']]) }
+              .compact
+          end
+
+          map = PG::TypeMapByOid.new
+          coders.each { |coder| map.add_coder(coder) }
+          @connection.type_map_for_results = map
+        end
+
+        def construct_coder(row, coder_class)
+          return unless coder_class
+          coder_class.new(oid: row['oid'].to_i, name: row['typname'])
+        end
+
+        ActiveRecord::Type.add_modifier({ array: true }, OID::Array, adapter: :postgresql)
+        ActiveRecord::Type.add_modifier({ range: true }, OID::Range, adapter: :postgresql)
+        ActiveRecord::Type.register(:bit, OID::Bit, adapter: :postgresql)
+        ActiveRecord::Type.register(:bit_varying, OID::BitVarying, adapter: :postgresql)
+        ActiveRecord::Type.register(:binary, OID::Bytea, adapter: :postgresql)
+        ActiveRecord::Type.register(:cidr, OID::Cidr, adapter: :postgresql)
+        ActiveRecord::Type.register(:date_time, OID::DateTime, adapter: :postgresql)
+        ActiveRecord::Type.register(:decimal, OID::Decimal, adapter: :postgresql)
+        ActiveRecord::Type.register(:enum, OID::Enum, adapter: :postgresql)
+        ActiveRecord::Type.register(:hstore, OID::Hstore, adapter: :postgresql)
+        ActiveRecord::Type.register(:inet, OID::Inet, adapter: :postgresql)
+        ActiveRecord::Type.register(:json, OID::Json, adapter: :postgresql)
+        ActiveRecord::Type.register(:jsonb, OID::Jsonb, adapter: :postgresql)
+        ActiveRecord::Type.register(:money, OID::Money, adapter: :postgresql)
+        ActiveRecord::Type.register(:point, OID::Point, adapter: :postgresql)
+        ActiveRecord::Type.register(:legacy_point, OID::Point, adapter: :postgresql)
+        ActiveRecord::Type.register(:rails_5_1_point, OID::Rails51Point, adapter: :postgresql)
+        ActiveRecord::Type.register(:uuid, OID::Uuid, adapter: :postgresql)
+        ActiveRecord::Type.register(:vector, OID::Vector, adapter: :postgresql)
+        ActiveRecord::Type.register(:xml, OID::Xml, adapter: :postgresql)
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/schema_cache.rb b/activerecord/lib/active_record/connection_adapters/schema_cache.rb
index 37ff4e4613..eee142378c 100644
--- a/activerecord/lib/active_record/connection_adapters/schema_cache.rb
+++ b/activerecord/lib/active_record/connection_adapters/schema_cache.rb
@@ -10,33 +10,46 @@ module ActiveRecord
         @columns      = {}
         @columns_hash = {}
         @primary_keys = {}
-        @tables       = {}
+        @data_sources = {}
+      end
+
+      def initialize_dup(other)
+        super
+        @columns      = @columns.dup
+        @columns_hash = @columns_hash.dup
+        @primary_keys = @primary_keys.dup
+        @data_sources = @data_sources.dup
       end
 
       def primary_keys(table_name)
-        @primary_keys[table_name] ||= table_exists?(table_name) ? connection.primary_key(table_name) : nil
+        @primary_keys[table_name] ||= data_source_exists?(table_name) ? connection.primary_key(table_name) : nil
       end
 
       # A cached lookup for table existence.
-      def table_exists?(name)
-        prepare_tables if @tables.empty?
-        return @tables[name] if @tables.key? name
+      def data_source_exists?(name)
+        prepare_data_sources if @data_sources.empty?
+        return @data_sources[name] if @data_sources.key? name
 
-        @tables[name] = connection.table_exists?(name)
+        @data_sources[name] = connection.data_source_exists?(name)
       end
+      alias table_exists? data_source_exists?
+      deprecate :table_exists? => "use #data_source_exists? instead"
+
 
       # Add internal cache for table with +table_name+.
       def add(table_name)
-        if table_exists?(table_name)
+        if data_source_exists?(table_name)
           primary_keys(table_name)
           columns(table_name)
           columns_hash(table_name)
         end
       end
 
-      def tables(name)
-        @tables[name]
+      def data_sources(name)
+        @data_sources[name]
       end
+      alias tables data_sources
+      deprecate :tables => "use #data_sources instead"
 
       # Get the columns for a table
       def columns(table_name)
@@ -56,36 +69,38 @@ module ActiveRecord
         @columns.clear
         @columns_hash.clear
         @primary_keys.clear
-        @tables.clear
+        @data_sources.clear
         @version = nil
       end
 
       def size
-        [@columns, @columns_hash, @primary_keys, @tables].map(&:size).inject :+
+        [@columns, @columns_hash, @primary_keys, @data_sources].map(&:size).inject :+
       end
 
-      # Clear out internal caches for table with +table_name+.
-      def clear_table_cache!(table_name)
-        @columns.delete table_name
-        @columns_hash.delete table_name
-        @primary_keys.delete table_name
-        @tables.delete table_name
+      # Clear out internal caches for the data source +name+.
+      def clear_data_source_cache!(name)
+        @columns.delete name
+        @columns_hash.delete name
+        @primary_keys.delete name
+        @data_sources.delete name
       end
+      alias clear_table_cache! clear_data_source_cache!
+      deprecate :clear_table_cache! => "use #clear_data_source_cache! instead"
 
       def marshal_dump
         # if we get current version during initialization, it happens stack over flow.
         @version = ActiveRecord::Migrator.current_version
-        [@version, @columns, @columns_hash, @primary_keys, @tables]
+        [@version, @columns, @columns_hash, @primary_keys, @data_sources]
       end
 
       def marshal_load(array)
-        @version, @columns, @columns_hash, @primary_keys, @tables = array
+        @version, @columns, @columns_hash, @primary_keys, @data_sources = array
       end
 
       private
 
-        def prepare_tables
-          connection.tables.each { |table| @tables[table] = true }
+        def prepare_data_sources
+          connection.data_sources.each { |source| @data_sources[source] = true }
         end
     end
   end
diff --git a/activerecord/lib/active_record/connection_adapters/sql_type_metadata.rb b/activerecord/lib/active_record/connection_adapters/sql_type_metadata.rb
new file mode 100644
index 0000000000..ccb7e154ee
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/sql_type_metadata.rb
@@ -0,0 +1,32 @@
+module ActiveRecord
+  # :stopdoc:
+  module ConnectionAdapters
+    class SqlTypeMetadata
+      attr_reader :sql_type, :type, :limit, :precision, :scale
+
+      def initialize(sql_type: nil, type: nil, limit: nil, precision: nil, scale: nil)
+        @sql_type = sql_type
+        @type = type
+        @limit = limit
+        @precision = precision
+        @scale = scale
+      end
+
+      def ==(other)
+        other.is_a?(SqlTypeMetadata) &&
+          attributes_for_hash == other.attributes_for_hash
+      end
+      alias eql? ==
+
+      def hash
+        attributes_for_hash.hash
+      end
+
+      protected
+
+      def attributes_for_hash
+        [self.class, sql_type, type, limit, precision, scale]
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/sqlite3/schema_creation.rb
new file mode 100644
index 0000000000..fe1dcbd710
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3/schema_creation.rb
@@ -0,0 +1,15 @@
+module ActiveRecord
+  module ConnectionAdapters
+    module SQLite3
+      class SchemaCreation < AbstractAdapter::SchemaCreation
+        private
+          def add_column_options!(sql, options)
+            if options[:collation]
+              sql << " COLLATE \"#{options[:collation]}\""
+            end
+            super
+          end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 03dfd29a0a..9028c1fcb9 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -1,6 +1,6 @@
 require 'active_record/connection_adapters/abstract_adapter'
 require 'active_record/connection_adapters/statement_pool'
-require 'arel/visitors/bind_visitor'
+require 'active_record/connection_adapters/sqlite3/schema_creation'
 
 gem 'sqlite3', '~> 1.3.6'
 require 'sqlite3'
@@ -41,25 +41,6 @@ module ActiveRecord
   end
 
   module ConnectionAdapters #:nodoc:
-    class SQLite3Binary < Type::Binary # :nodoc:
-      def cast_value(value)
-        if value.encoding != Encoding::ASCII_8BIT
-          value = value.force_encoding(Encoding::ASCII_8BIT)
-        end
-        value
-      end
-    end
-
-    class SQLite3String < Type::String # :nodoc:
-      def type_cast_for_database(value)
-        if value.is_a?(::String) && value.encoding == Encoding::ASCII_8BIT
-          value.encode(Encoding::UTF_8)
-        else
-          super
-        end
-      end
-    end
-
     # The SQLite3 adapter works SQLite 3.6.16 or newer
     # with the sqlite3-ruby drivers (available as gem from https://rubygems.org/gems/sqlite3).
     #
@@ -84,65 +65,31 @@ module ActiveRecord
         boolean:      { name: "boolean" }
       }
 
-      class Version
-        include Comparable
-
-        def initialize(version_string)
-          @version = version_string.split('.').map(&:to_i)
-        end
-
-        def <=>(version_string)
-          @version <=> version_string.split('.').map(&:to_i)
-        end
-      end
-
       class StatementPool < ConnectionAdapters::StatementPool
-        def initialize(connection, max)
-          super
-          @cache = Hash.new { |h,pid| h[pid] = {} }
-        end
-
-        def each(&block); cache.each(&block); end
-        def key?(key);    cache.key?(key); end
-        def [](key);      cache[key]; end
-        def length;       cache.length; end
-
-        def []=(sql, key)
-          while @max <= cache.size
-            dealloc(cache.shift.last[:stmt])
-          end
-          cache[sql] = key
-        end
-
-        def clear
-          cache.each_value do |hash|
-            dealloc hash[:stmt]
-          end
-          cache.clear
-        end
-
         private
-        def cache
-          @cache[$$]
-        end
 
         def dealloc(stmt)
-          stmt.close unless stmt.closed?
+          stmt[:stmt].close unless stmt[:stmt].closed?
         end
       end
 
+      def schema_creation # :nodoc:
+        SQLite3::SchemaCreation.new self
+      end
+
       def initialize(connection, logger, connection_options, config)
         super(connection, logger)
 
         @active     = nil
-        @statements = StatementPool.new(@connection,
-                                        self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
+        @statements = StatementPool.new(self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
         @config = config
 
         @visitor = Arel::Visitors::SQLite.new self
+        @quoted_column_names = {}
 
         if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
           @prepared_statements = true
+          @visitor.extend(DetermineIfPreparableVisitor)
         else
           @prepared_statements = false
         end
@@ -239,6 +186,12 @@ module ActiveRecord
         case value
         when BigDecimal
           value.to_f
+        when String
+          if value.encoding == Encoding::ASCII_8BIT
+            super(value.encode(Encoding::UTF_8))
+          else
+            super
+          end
         else
           super
         end
@@ -253,7 +206,7 @@ module ActiveRecord
       end
 
       def quote_column_name(name) #:nodoc:
-        %Q("#{name.to_s.gsub('"', '""')}")
+        @quoted_column_names[name] ||= %Q("#{name.to_s.gsub('"', '""')}")
       end
 
       #--
@@ -266,7 +219,7 @@ module ActiveRecord
       end
 
       class ExplainPrettyPrinter
-        # Pretty prints the result of a EXPLAIN QUERY PLAN in a way that resembles
+        # Pretty prints the result of an EXPLAIN QUERY PLAN in a way that resembles
         # the output of the SQLite shell:
         #
         #   0|0|0|SEARCH TABLE users USING INTEGER PRIMARY KEY (rowid=?) (~1 rows)
@@ -279,17 +232,18 @@ module ActiveRecord
         end
       end
 
-      def exec_query(sql, name = nil, binds = [])
-        type_casted_binds = binds.map { |col, val|
-          [col, type_cast(val, col)]
-        }
+      def exec_query(sql, name = nil, binds = [], prepare: false)
+        type_casted_binds = binds.map { |attr| type_cast(attr.value_for_database) }
 
-        log(sql, name, type_casted_binds) do
+        log(sql, name, binds) do
           # Don't cache statements if they are not prepared
-          if without_prepared_statement?(binds)
+          unless prepare
             stmt    = @connection.prepare(sql)
             begin
               cols    = stmt.columns
+              unless without_prepared_statement?(binds)
+                stmt.bind_params(type_casted_binds)
+              end
               records = stmt.to_a
             ensure
               stmt.close
@@ -302,7 +256,7 @@ module ActiveRecord
             stmt = cache[:stmt]
             cols = cache[:cols] ||= stmt.columns
             stmt.reset!
-            stmt.bind_params type_casted_binds.map { |_, val| val }
+            stmt.bind_params(type_casted_binds)
           end
 
           ActiveRecord::Result.new(cols, stmt.to_a)
@@ -357,21 +311,32 @@ module ActiveRecord
 
       # SCHEMA STATEMENTS ========================================
 
-      def tables(name = nil, table_name = nil) #:nodoc:
-        sql = <<-SQL
-          SELECT name
-          FROM sqlite_master
-          WHERE (type = 'table' OR type = 'view') AND NOT name = 'sqlite_sequence'
-        SQL
-        sql << " AND name = #{quote_table_name(table_name)}" if table_name
-
-        exec_query(sql, 'SCHEMA').map do |row|
-          row['name']
-        end
+      def tables(name = nil) # :nodoc:
+        select_values("SELECT name FROM sqlite_master WHERE type IN ('table','view') AND name <> 'sqlite_sequence'", 'SCHEMA')
       end
+      alias data_sources tables
 
       def table_exists?(table_name)
-        table_name && tables(nil, table_name).any?
+        return false unless table_name.present?
+
+        sql = "SELECT name FROM sqlite_master WHERE type IN ('table','view') AND name <> 'sqlite_sequence'"
+        sql << " AND name = #{quote(table_name)}"
+
+        select_values(sql, 'SCHEMA').any?
+      end
+      alias data_source_exists? table_exists?
+
+      def views # :nodoc:
+        select_values("SELECT name FROM sqlite_master WHERE type = 'view' AND name <> 'sqlite_sequence'", 'SCHEMA')
+      end
+
+      def view_exists?(view_name) # :nodoc:
+        return false unless view_name.present?
+
+        sql = "SELECT name FROM sqlite_master WHERE type = 'view' AND name <> 'sqlite_sequence'"
+        sql << " AND name = #{quote(view_name)}"
+
+        select_values(sql, 'SCHEMA').any?
       end
 
       # Returns an array of +Column+ objects for the table specified by +table_name+.
@@ -386,9 +351,10 @@ module ActiveRecord
             field["dflt_value"] = $1.gsub('""', '"')
           end
 
+          collation = field['collation']
           sql_type = field['type']
-          cast_type = lookup_cast_type(sql_type)
-          new_column(field['name'], field['dflt_value'], cast_type, sql_type, field['notnull'].to_i == 0)
+          type_metadata = fetch_type_metadata(sql_type)
+          new_column(field['name'], field['dflt_value'], type_metadata, field['notnull'].to_i == 0, nil, collation)
         end
       end
 
@@ -417,13 +383,13 @@ module ActiveRecord
         end
       end
 
-      def primary_key(table_name) #:nodoc:
+      def primary_keys(table_name) # :nodoc:
         pks = table_structure(table_name).select { |f| f['pk'] > 0 }
-        return nil unless pks.count == 1
-        pks[0]['name']
+        pks.sort_by { |f| f['pk'] }.map { |f| f['name'] }
       end
 
-      def remove_index!(table_name, index_name) #:nodoc:
+      def remove_index(table_name, options = {}) #:nodoc:
+        index_name = index_name_for_remove(table_name, options)
         exec_query "DROP INDEX #{quote_column_name(index_name)}"
       end
 
@@ -458,13 +424,15 @@ module ActiveRecord
         end
       end
 
-      def change_column_default(table_name, column_name, default) #:nodoc:
+      def change_column_default(table_name, column_name, default_or_changes) #:nodoc:
+        default = extract_new_default_value(default_or_changes)
+
         alter_table(table_name) do |definition|
           definition[column_name].default = default
         end
       end
 
-      def change_column_null(table_name, column_name, null, default = nil)
+      def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
         unless null || default.nil?
           exec_query("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
         end
@@ -483,6 +451,7 @@ module ActiveRecord
             self.null    = options[:null] if options.include?(:null)
             self.precision = options[:precision] if options.include?(:precision)
             self.scale   = options[:scale] if options.include?(:scale)
+            self.collation = options[:collation] if options.include?(:collation)
           end
         end
       end
@@ -495,16 +464,10 @@ module ActiveRecord
 
       protected
 
-        def initialize_type_map(m)
-          super
-          m.register_type(/binary/i, SQLite3Binary.new)
-          register_class_with_limit m, %r(char)i, SQLite3String
-        end
-
         def table_structure(table_name)
-          structure = exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", 'SCHEMA').to_hash
+          structure = exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", 'SCHEMA')
           raise(ActiveRecord::StatementInvalid, "Could not find table '#{table_name}'") if structure.empty?
-          structure
+          table_structure_with_collation(table_name, structure)
         end
 
         def alter_table(table_name, options = {}) #:nodoc:
@@ -539,7 +502,7 @@ module ActiveRecord
               @definition.column(column_name, column.type,
                 :limit => column.limit, :default => column.default,
                 :precision => column.precision, :scale => column.scale,
-                :null => column.null)
+                :null => column.null, collation: column.collation)
             end
             yield @definition if block_given?
           end
@@ -601,6 +564,46 @@ module ActiveRecord
             super
           end
         end
+
+      private
+        COLLATE_REGEX = /.*\"(\w+)\".*collate\s+\"(\w+)\".*/i.freeze
+
+        def table_structure_with_collation(table_name, basic_structure)
+          collation_hash = {}
+          sql            = "SELECT sql FROM
+                              (SELECT * FROM sqlite_master UNION ALL
+                               SELECT * FROM sqlite_temp_master)
+                            WHERE type='table' and name='#{ table_name }' \;"
+
+          # Result will have following sample string
+          # CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
+          #                       "password_digest" varchar COLLATE "NOCASE");
+          result = exec_query(sql, 'SCHEMA').first
+
+          if result
+            # Splitting with left parantheses and picking up last will return all
+            # columns separated with comma(,).
+            columns_string = result["sql"].split('(').last
+
+            columns_string.split(',').each do |column_string|
+              # This regex will match the column name and collation type and will save
+              # the value in $1 and $2 respectively.
+              collation_hash[$1] = $2 if (COLLATE_REGEX =~ column_string)
+            end
+
+            basic_structure.map! do |column|
+              column_name = column['name']
+
+              if collation_hash.has_key? column_name
+                column['collation'] = collation_hash[column_name]
+              end
+
+              column
+            end
+          else
+            basic_structure.to_hash
+          end
+        end
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/statement_pool.rb b/activerecord/lib/active_record/connection_adapters/statement_pool.rb
index c6b1bc8b5b..57463dd749 100644
--- a/activerecord/lib/active_record/connection_adapters/statement_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/statement_pool.rb
@@ -3,36 +3,53 @@ module ActiveRecord
     class StatementPool
       include Enumerable
 
-      def initialize(connection, max = 1000)
-        @connection = connection
-        @max        = max
+      def initialize(max = 1000)
+        @cache = Hash.new { |h,pid| h[pid] = {} }
+        @max = max
       end
 
-      def each
-        raise NotImplementedError
+      def each(&block)
+        cache.each(&block)
       end
 
       def key?(key)
-        raise NotImplementedError
+        cache.key?(key)
       end
 
       def [](key)
-        raise NotImplementedError
+        cache[key]
       end
 
       def length
-        raise NotImplementedError
+        cache.length
       end
 
-      def []=(sql, key)
-        raise NotImplementedError
+      def []=(sql, stmt)
+        while @max <= cache.size
+          dealloc(cache.shift.last)
+        end
+        cache[sql] = stmt
       end
 
       def clear
-        raise NotImplementedError
+        cache.each_value do |stmt|
+          dealloc stmt
+        end
+        cache.clear
       end
 
       def delete(key)
+        dealloc cache[key]
+        cache.delete(key)
+      end
+
+      private
+
+      def cache
+        @cache[Process.pid]
+      end
+
+      def dealloc(stmt)
         raise NotImplementedError
       end
     end
diff --git a/activerecord/lib/active_record/connection_handling.rb b/activerecord/lib/active_record/connection_handling.rb
index 984af79642..aedef54928 100644
--- a/activerecord/lib/active_record/connection_handling.rb
+++ b/activerecord/lib/active_record/connection_handling.rb
@@ -5,7 +5,7 @@ module ActiveRecord
 
     # Establishes the connection to the database. Accepts a hash as input where
     # the <tt>:adapter</tt> key must be specified with the name of a database adapter (in lower-case)
-    # example for regular databases (MySQL, Postgresql, etc):
+    # example for regular databases (MySQL, PostgreSQL, etc):
     #
     #   ActiveRecord::Base.establish_connection(
     #     adapter:  "mysql",
@@ -35,14 +35,14 @@ module ActiveRecord
     #     "postgres://myuser:mypass@localhost/somedatabase"
     #   )
     #
-    # In case <tt>ActiveRecord::Base.configurations</tt> is set (Rails
-    # automatically loads the contents of config/database.yml into it),
+    # In case {ActiveRecord::Base.configurations}[rdoc-ref:Core.configurations]
+    # is set (Rails automatically loads the contents of config/database.yml into it),
     # a symbol can also be given as argument, representing a key in the
     # configuration hash:
     #
     #   ActiveRecord::Base.establish_connection(:production)
     #
-    # The exceptions AdapterNotSpecified, AdapterNotFound and ArgumentError
+    # The exceptions AdapterNotSpecified, AdapterNotFound and +ArgumentError+
     # may be returned on an error.
     def establish_connection(spec = nil)
       spec     ||= DEFAULT_ENV.call.to_sym
@@ -88,7 +88,7 @@ module ActiveRecord
     end
 
     def connection_id
-      ActiveRecord::RuntimeRegistry.connection_id
+      ActiveRecord::RuntimeRegistry.connection_id ||= Thread.current.object_id
     end
 
     def connection_id=(connection_id)
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index a7aff9f724..142b6e8599 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -85,10 +85,30 @@ module ActiveRecord
       mattr_accessor :dump_schema_after_migration, instance_writer: false
       self.dump_schema_after_migration = true
 
+      ##
+      # :singleton-method:
+      # Specifies which database schemas to dump when calling db:structure:dump.
+      # If the value is :schema_search_path (the default), any schemas listed in
+      # schema_search_path are dumped. Use :all to dump all schemas regardless
+      # of schema_search_path, or a string of comma separated schemas for a
+      # custom list.
+      mattr_accessor :dump_schemas, instance_writer: false
+      self.dump_schemas = :schema_search_path
+
+      ##
+      # :singleton-method:
+      # Specify a threshold for the size of query result sets. If the number of
+      # records in the set exceeds the threshold, a warning is logged. This can
+      # be used to identify queries which load thousands of records and
+      # potentially cause memory bloat.
+      mattr_accessor :warn_on_records_fetched_greater_than, instance_writer: false
+      self.warn_on_records_fetched_greater_than = nil
+
       mattr_accessor :maintain_test_schema, instance_accessor: false
 
+      mattr_accessor :belongs_to_required_by_default, instance_accessor: false
+
       class_attribute :default_connection_handler, instance_writer: false
-      class_attribute :find_by_statement_cache
 
       def self.connection_handler
         ActiveRecord::RuntimeRegistry.connection_handler || default_connection_handler
@@ -107,24 +127,22 @@ module ActiveRecord
         super
       end
 
-      def initialize_find_by_cache
-        self.find_by_statement_cache = {}.extend(Mutex_m)
+      def initialize_find_by_cache # :nodoc:
+        @find_by_statement_cache = {}.extend(Mutex_m)
       end
 
-      def inherited(child_class)
+      def inherited(child_class) # :nodoc:
+        # initialize cache at class definition for thread safety
         child_class.initialize_find_by_cache
         super
       end
 
-      def find(*ids)
+      def find(*ids) # :nodoc:
         # We don't have cache keys for this stuff yet
         return super unless ids.length == 1
-        # Allow symbols to super to maintain compatibility for deprecated finders until Rails 5
-        return super if ids.first.kind_of?(Symbol)
         return super if block_given? ||
                         primary_key.nil? ||
-                        default_scopes.any? ||
-                        current_scope ||
+                        scope_attributes? ||
                         columns_hash.include?(inheritance_column) ||
                         ids.first.kind_of?(Array)
 
@@ -136,48 +154,45 @@ module ActiveRecord
             Please pass the id of the object by calling `.id`
           MSG
         end
+
         key = primary_key
 
-        s = find_by_statement_cache[key] || find_by_statement_cache.synchronize {
-          find_by_statement_cache[key] ||= StatementCache.create(connection) { |params|
-            where(key => params.bind).limit(1)
-          }
+        statement = cached_find_by_statement(key) { |params|
+          where(key => params.bind).limit(1)
         }
-        record = s.execute([id], self, connection).first
+        record = statement.execute([id], self, connection).first
         unless record
-          raise RecordNotFound, "Couldn't find #{name} with '#{primary_key}'=#{id}"
+          raise RecordNotFound.new("Couldn't find #{name} with '#{primary_key}'=#{id}",
+                                   name, primary_key, id)
         end
         record
       rescue RangeError
-        raise RecordNotFound, "Couldn't find #{name} with an out of range value for '#{primary_key}'"
+        raise RecordNotFound.new("Couldn't find #{name} with an out of range value for '#{primary_key}'",
+                                 name, primary_key)
       end
 
-      def find_by(*args)
-        return super if current_scope || !(Hash === args.first) || reflect_on_all_aggregations.any?
-        return super if default_scopes.any?
+      def find_by(*args) # :nodoc:
+        return super if scope_attributes? || !(Hash === args.first) || reflect_on_all_aggregations.any?
 
         hash = args.first
 
         return super if hash.values.any? { |v|
-          v.nil? || Array === v || Hash === v
+          v.nil? || Array === v || Hash === v || Relation === v
         }
 
         # We can't cache Post.find_by(author: david) ...yet
         return super unless hash.keys.all? { |k| columns_hash.has_key?(k.to_s) }
 
-        key  = hash.keys
+        keys = hash.keys
 
-        klass = self
-        s = find_by_statement_cache[key] || find_by_statement_cache.synchronize {
-          find_by_statement_cache[key] ||= StatementCache.create(connection) { |params|
-            wheres = key.each_with_object({}) { |param,o|
-              o[param] = params.bind
-            }
-            klass.where(wheres).limit(1)
+        statement = cached_find_by_statement(keys) { |params|
+          wheres = keys.each_with_object({}) { |param, o|
+            o[param] = params.bind
           }
+          where(wheres).limit(1)
         }
         begin
-          s.execute(hash.values, self, connection).first
+          statement.execute(hash.values, self, connection).first
         rescue TypeError => e
           raise ActiveRecord::StatementInvalid.new(e.message, e)
         rescue RangeError
@@ -185,11 +200,11 @@ module ActiveRecord
         end
       end
 
-      def find_by!(*args)
-        find_by(*args) or raise RecordNotFound.new("Couldn't find #{name}")
+      def find_by!(*args) # :nodoc:
+        find_by(*args) or raise RecordNotFound.new("Couldn't find #{name}", name)
       end
 
-      def initialize_generated_modules
+      def initialize_generated_modules # :nodoc:
         generated_association_methods
       end
 
@@ -210,7 +225,7 @@ module ActiveRecord
         elsif !connected?
           "#{super} (call '#{super}.connection' to establish a connection)"
         elsif table_exists?
-          attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', '
+          attr_list = attribute_types.map { |name, type| "#{name}: #{type.type}" } * ', '
           "#{super}(#{attr_list})"
         else
           "#{super}(Table doesn't exist)"
@@ -251,6 +266,12 @@ module ActiveRecord
 
       private
 
+      def cached_find_by_statement(key, &block) # :nodoc:
+        @find_by_statement_cache[key] || @find_by_statement_cache.synchronize {
+          @find_by_statement_cache[key] ||= StatementCache.create(connection, &block)
+        }
+      end
+
       def relation # :nodoc:
         relation = Relation.create(self, arel_table, predicate_builder)
 
@@ -275,7 +296,7 @@ module ActiveRecord
     #   # Instantiates a single new object
     #   User.new(first_name: 'Jamie')
     def initialize(attributes = nil)
-      @attributes = self.class._default_attributes.dup
+      @attributes = self.class._default_attributes.deep_dup
       self.class.define_attribute_methods
 
       init_internals
@@ -287,17 +308,22 @@ module ActiveRecord
       _run_initialize_callbacks
     end
 
-    # Initialize an empty model object from +coder+. +coder+ must contain
-    # the attributes necessary for initializing an empty model object. For
-    # example:
+    # Initialize an empty model object from +coder+. +coder+ should be
+    # the result of previously encoding an Active Record model, using
+    # #encode_with.
     #
     #   class Post < ActiveRecord::Base
     #   end
     #
+    #   old_post = Post.new(title: "hello world")
+    #   coder = {}
+    #   old_post.encode_with(coder)
+    #
     #   post = Post.allocate
-    #   post.init_with('attributes' => { 'title' => 'hello world' })
+    #   post.init_with(coder)
     #   post.title # => 'hello world'
     def init_with(coder)
+      coder = LegacyYamlAdapter.convert(self.class, coder)
       @attributes = coder['attributes']
 
       init_internals
@@ -340,14 +366,11 @@ module ActiveRecord
 
     ##
     def initialize_dup(other) # :nodoc:
-      @attributes = @attributes.dup
+      @attributes = @attributes.deep_dup
       @attributes.reset(self.class.primary_key)
 
       _run_initialize_callbacks
 
-      @aggregation_cache = {}
-      @association_cache = {}
-
       @new_record  = true
       @destroyed   = false
 
@@ -356,7 +379,7 @@ module ActiveRecord
 
     # Populate +coder+ with attributes about this record that should be
     # serialized. The structure of +coder+ defined in this method is
-    # guaranteed to match the structure of +coder+ passed to the +init_with+
+    # guaranteed to match the structure of +coder+ passed to the #init_with
     # method.
     #
     # Example:
@@ -371,6 +394,7 @@ module ActiveRecord
       coder['raw_attributes'] = attributes_before_type_cast
       coder['attributes'] = @attributes
       coder['new_record'] = new_record?
+      coder['active_record_yaml_version'] = 1
     end
 
     # Returns true if +comparison_object+ is the same exact object, or +comparison_object+
@@ -453,9 +477,10 @@ module ActiveRecord
       "#<#{self.class} #{inspection}>"
     end
 
-    # Takes a PP and prettily prints this record to it, allowing you to get a nice result from `pp record`
+    # Takes a PP and prettily prints this record to it, allowing you to get a nice result from <tt>pp record</tt>
     # when pp is required.
     def pretty_print(pp)
+      return super if custom_inspect_method_defined?
       pp.object_address_group(self) do
         if defined?(@attributes) && @attributes
           column_names = self.class.column_names.select { |name| has_attribute?(name) || new_record? }
@@ -481,51 +506,8 @@ module ActiveRecord
       Hash[methods.map! { |method| [method, public_send(method)] }].with_indifferent_access
     end
 
-    def set_transaction_state(state) # :nodoc:
-      @transaction_state = state
-    end
-
-    def has_transactional_callbacks? # :nodoc:
-      !_rollback_callbacks.empty? || !_commit_callbacks.empty? || !_create_callbacks.empty?
-    end
-
     private
 
-    # Updates the attributes on this particular ActiveRecord object so that
-    # if it is associated with a transaction, then the state of the AR object
-    # will be updated to reflect the current state of the transaction
-    #
-    # The @transaction_state variable stores the states of the associated
-    # transaction. This relies on the fact that a transaction can only be in
-    # one rollback or commit (otherwise a list of states would be required)
-    # Each AR object inside of a transaction carries that transaction's
-    # TransactionState.
-    #
-    # This method checks to see if the ActiveRecord object's state reflects
-    # the TransactionState, and rolls back or commits the ActiveRecord object
-    # as appropriate.
-    #
-    # Since ActiveRecord objects can be inside multiple transactions, this
-    # method recursively goes through the parent of the TransactionState and
-    # checks if the ActiveRecord object reflects the state of the object.
-    def sync_with_transaction_state
-      update_attributes_from_transaction_state(@transaction_state, 0)
-    end
-
-    def update_attributes_from_transaction_state(transaction_state, depth)
-      if transaction_state && transaction_state.finalized? && !has_transactional_callbacks?
-        unless @reflects_state[depth]
-          restore_transaction_record_state if transaction_state.rolledback?
-          clear_transaction_record_state
-          @reflects_state[depth] = true
-        end
-
-        if transaction_state.parent && !@reflects_state[depth+1]
-          update_attributes_from_transaction_state(transaction_state.parent, depth+1)
-        end
-      end
-    end
-
     # Under Ruby 1.9, Array#flatten will call #to_ary (recursively) on each of the elements
     # of the array, and then rescues from the possible NoMethodError. If those elements are
     # ActiveRecord::Base's, then this triggers the various method_missing's that we have,
@@ -539,8 +521,6 @@ module ActiveRecord
     end
 
     def init_internals
-      @aggregation_cache        = {}
-      @association_cache        = {}
       @readonly                 = false
       @destroyed                = false
       @marked_for_destruction   = false
@@ -549,7 +529,6 @@ module ActiveRecord
       @txn                      = nil
       @_start_transaction_state = {}
       @transaction_state        = nil
-      @reflects_state           = [false]
     end
 
     def initialize_internals_callback
@@ -560,5 +539,9 @@ module ActiveRecord
         @attributes = @attributes.dup
       end
     end
+
+    def custom_inspect_method_defined?
+      self.class.instance_method(:inspect).owner != ActiveRecord::Base.instance_method(:inspect).owner
+    end
   end
 end
diff --git a/activerecord/lib/active_record/counter_cache.rb b/activerecord/lib/active_record/counter_cache.rb
index 7d8e0a2063..9e7d391c70 100644
--- a/activerecord/lib/active_record/counter_cache.rb
+++ b/activerecord/lib/active_record/counter_cache.rb
@@ -45,14 +45,14 @@ module ActiveRecord
       end
 
       # A generic "counter updater" implementation, intended primarily to be
-      # used by increment_counter and decrement_counter, but which may also
+      # used by #increment_counter and #decrement_counter, but which may also
       # be useful on its own. It simply does a direct SQL update for the record
       # with the given ID, altering the given hash of counters by the amount
       # given by the corresponding value:
       #
       # ==== Parameters
       #
-      # * +id+ - The id of the object you wish to update a counter on or an Array of ids.
+      # * +id+ - The id of the object you wish to update a counter on or an array of ids.
       # * +counters+ - A Hash containing the names of the fields
       #   to update as keys and the amount to update the field by as values.
       #
@@ -86,14 +86,14 @@ module ActiveRecord
       # Increment a numeric field by one, via a direct SQL update.
       #
       # This method is used primarily for maintaining counter_cache columns that are
-      # used to store aggregate values. For example, a DiscussionBoard may cache
+      # used to store aggregate values. For example, a +DiscussionBoard+ may cache
       # posts_count and comments_count to avoid running an SQL query to calculate the
       # number of posts and comments there are, each time it is displayed.
       #
       # ==== Parameters
       #
       # * +counter_name+ - The name of the field that should be incremented.
-      # * +id+ - The id of the object that should be incremented or an Array of ids.
+      # * +id+ - The id of the object that should be incremented or an array of ids.
       #
       # ==== Examples
       #
@@ -105,13 +105,13 @@ module ActiveRecord
 
       # Decrement a numeric field by one, via a direct SQL update.
       #
-      # This works the same as increment_counter but reduces the column value by
+      # This works the same as #increment_counter but reduces the column value by
       # 1 instead of increasing it.
       #
       # ==== Parameters
       #
       # * +counter_name+ - The name of the field that should be decremented.
-      # * +id+ - The id of the object that should be decremented or an Array of ids.
+      # * +id+ - The id of the object that should be decremented or an array of ids.
       #
       # ==== Examples
       #
@@ -156,7 +156,7 @@ module ActiveRecord
 
       def each_counter_cached_associations
         _reflections.each do |name, reflection|
-          yield association(name) if reflection.belongs_to? && reflection.counter_cache_column
+          yield association(name.to_sym) if reflection.belongs_to? && reflection.counter_cache_column
         end
       end
 
diff --git a/activerecord/lib/active_record/enum.rb b/activerecord/lib/active_record/enum.rb
index f053372cfb..8fba6fcc35 100644
--- a/activerecord/lib/active_record/enum.rb
+++ b/activerecord/lib/active_record/enum.rb
@@ -18,10 +18,9 @@ module ActiveRecord
   #   conversation.archived? # => true
   #   conversation.status    # => "archived"
   #
-  #   # conversation.update! status: 1
+  #   # conversation.status = 1
   #   conversation.status = "archived"
   #
-  #   # conversation.update! status: nil
   #   conversation.status = nil
   #   conversation.status.nil? # => true
   #   conversation.status      # => nil
@@ -32,6 +31,12 @@ module ActiveRecord
   #   Conversation.active
   #   Conversation.archived
   #
+  # Of course, you can also query them directly if the scopes don't fit your
+  # needs:
+  #
+  #   Conversation.where(status: [:active, :archived])
+  #   Conversation.where.not(status: :active)
+  #
   # You can set the default value from the database declaration, like:
   #
   #   create_table :conversations do |t|
@@ -41,13 +46,13 @@ module ActiveRecord
   # Good practice is to let the first declared status be the default.
   #
   # Finally, it's also possible to explicitly map the relation between attribute and
-  # database integer with a +Hash+:
+  # database integer with a hash:
   #
   #   class Conversation < ActiveRecord::Base
   #     enum status: { active: 0, archived: 1 }
   #   end
   #
-  # Note that when an +Array+ is used, the implicit mapping from the values to database
+  # Note that when an array is used, the implicit mapping from the values to database
   # integers is derived from the order the values appear in the array. In the example,
   # <tt>:active</tt> is mapped to +0+ as it's the first element, and <tt>:archived</tt>
   # is mapped to +1+. In general, the +i+-th element is mapped to <tt>i-1</tt> in the
@@ -55,19 +60,39 @@ module ActiveRecord
   #
   # Therefore, once a value is added to the enum array, its position in the array must
   # be maintained, and new values should only be added to the end of the array. To
-  # remove unused values, the explicit +Hash+ syntax should be used.
+  # remove unused values, the explicit hash syntax should be used.
   #
   # In rare circumstances you might need to access the mapping directly.
   # The mappings are exposed through a class method with the pluralized attribute
-  # name:
+  # name, which return the mapping in a +HashWithIndifferentAccess+:
   #
-  #   Conversation.statuses # => { "active" => 0, "archived" => 1 }
+  #   Conversation.statuses[:active]    # => 0
+  #   Conversation.statuses["archived"] # => 1
   #
-  # Use that class method when you need to know the ordinal value of an enum:
+  # Use that class method when you need to know the ordinal value of an enum.
+  # For example, you can use that when manually building SQL strings:
   #
   #   Conversation.where("status <> ?", Conversation.statuses[:archived])
   #
-  # Where conditions on an enum attribute must use the ordinal value of an enum.
+  # You can use the +:_prefix+ or +:_suffix+ options when you need to define
+  # multiple enums with same values. If the passed value is +true+, the methods
+  # are prefixed/suffixed with the name of the enum. It is also possible to
+  # supply a custom value:
+  #
+  #   class Conversation < ActiveRecord::Base
+  #     enum status: [:active, :archived], _suffix: true
+  #     enum comments_status: [:active, :inactive], _prefix: :comments
+  #   end
+  #
+  # With the above example, the bang and predicate methods along with the
+  # associated scopes are now prefixed and/or suffixed accordingly:
+  #
+  #   conversation.active_status!
+  #   conversation.archived_status? # => false
+  #
+  #   conversation.comments_inactive!
+  #   conversation.comments_active? # => false
+
   module Enum
     def self.extended(base) # :nodoc:
       base.class_attribute(:defined_enums)
@@ -79,8 +104,48 @@ module ActiveRecord
       super
     end
 
+    class EnumType < Type::Value
+      def initialize(name, mapping)
+        @name = name
+        @mapping = mapping
+      end
+
+      def cast(value)
+        return if value.blank?
+
+        if mapping.has_key?(value)
+          value.to_s
+        elsif mapping.has_value?(value)
+          mapping.key(value)
+        else
+          assert_valid_value(value)
+        end
+      end
+
+      def deserialize(value)
+        return if value.nil?
+        mapping.key(value.to_i)
+      end
+
+      def serialize(value)
+        mapping.fetch(value, value)
+      end
+
+      def assert_valid_value(value)
+        unless value.blank? || mapping.has_key?(value) || mapping.has_value?(value)
+          raise ArgumentError, "'#{value}' is not a valid #{name}"
+        end
+      end
+
+      protected
+
+      attr_reader :name, :mapping
+    end
+
     def enum(definitions)
       klass = self
+      enum_prefix = definitions.delete(:_prefix)
+      enum_suffix = definitions.delete(:_suffix)
       definitions.each do |name, values|
         # statuses = { }
         enum_values = ActiveSupport::HashWithIndifferentAccess.new
@@ -90,45 +155,39 @@ module ActiveRecord
         detect_enum_conflict!(name, name.to_s.pluralize, true)
         klass.singleton_class.send(:define_method, name.to_s.pluralize) { enum_values }
 
-        _enum_methods_module.module_eval do
-          # def status=(value) self[:status] = statuses[value] end
-          klass.send(:detect_enum_conflict!, name, "#{name}=")
-          define_method("#{name}=") { |value|
-            if enum_values.has_key?(value) || value.blank?
-              self[name] = enum_values[value]
-            elsif enum_values.has_value?(value)
-              # Assigning a value directly is not a end-user feature, hence it's not documented.
-              # This is used internally to make building objects from the generated scopes work
-              # as expected, i.e. +Conversation.archived.build.archived?+ should be true.
-              self[name] = value
-            else
-              raise ArgumentError, "'#{value}' is not a valid #{name}"
-            end
-          }
-
-          # def status() statuses.key self[:status] end
-          klass.send(:detect_enum_conflict!, name, name)
-          define_method(name) { enum_values.key self[name] }
+        detect_enum_conflict!(name, name)
+        detect_enum_conflict!(name, "#{name}=")
 
-          # def status_before_type_cast() statuses.key self[:status] end
-          klass.send(:detect_enum_conflict!, name, "#{name}_before_type_cast")
-          define_method("#{name}_before_type_cast") { enum_values.key self[name] }
+        attribute name, EnumType.new(name, enum_values)
 
+        _enum_methods_module.module_eval do
           pairs = values.respond_to?(:each_pair) ? values.each_pair : values.each_with_index
           pairs.each do |value, i|
+            if enum_prefix == true
+              prefix = "#{name}_"
+            elsif enum_prefix
+              prefix = "#{enum_prefix}_"
+            end
+            if enum_suffix == true
+              suffix = "_#{name}"
+            elsif enum_suffix
+              suffix = "_#{enum_suffix}"
+            end
+
+            value_method_name = "#{prefix}#{value}#{suffix}"
             enum_values[value] = i
 
             # def active?() status == 0 end
-            klass.send(:detect_enum_conflict!, name, "#{value}?")
-            define_method("#{value}?") { self[name] == i }
+            klass.send(:detect_enum_conflict!, name, "#{value_method_name}?")
+            define_method("#{value_method_name}?") { self[name] == value.to_s }
 
             # def active!() update! status: :active end
-            klass.send(:detect_enum_conflict!, name, "#{value}!")
-            define_method("#{value}!") { update! name => value }
+            klass.send(:detect_enum_conflict!, name, "#{value_method_name}!")
+            define_method("#{value_method_name}!") { update! name => value }
 
             # scope :active, -> { where status: 0 }
-            klass.send(:detect_enum_conflict!, name, value, true)
-            klass.scope value, -> { klass.where name => i }
+            klass.send(:detect_enum_conflict!, name, value_method_name, true)
+            klass.scope value_method_name, -> { klass.where name => value }
           end
         end
         defined_enums[name.to_s] = enum_values
@@ -138,25 +197,7 @@ module ActiveRecord
     private
       def _enum_methods_module
         @_enum_methods_module ||= begin
-          mod = Module.new do
-            private
-              def save_changed_attribute(attr_name, old)
-                if (mapping = self.class.defined_enums[attr_name.to_s])
-                  value = _read_attribute(attr_name)
-                  if attribute_changed?(attr_name)
-                    if mapping[old] == value
-                      clear_attribute_changes([attr_name])
-                    end
-                  else
-                    if old != value
-                      set_attribute_was(attr_name, mapping.key(old))
-                    end
-                  end
-                else
-                  super
-                end
-              end
-          end
+          mod = Module.new
           include mod
           mod
         end
@@ -169,30 +210,22 @@ module ActiveRecord
 
       def detect_enum_conflict!(enum_name, method_name, klass_method = false)
         if klass_method && dangerous_class_method?(method_name)
-          raise ArgumentError, ENUM_CONFLICT_MESSAGE % {
-            enum: enum_name,
-            klass: self.name,
-            type: 'class',
-            method: method_name,
-            source: 'Active Record'
-          }
+          raise_conflict_error(enum_name, method_name, type: 'class')
         elsif !klass_method && dangerous_attribute_method?(method_name)
-          raise ArgumentError, ENUM_CONFLICT_MESSAGE % {
-            enum: enum_name,
-            klass: self.name,
-            type: 'instance',
-            method: method_name,
-            source: 'Active Record'
-          }
+          raise_conflict_error(enum_name, method_name)
         elsif !klass_method && method_defined_within?(method_name, _enum_methods_module, Module)
-          raise ArgumentError, ENUM_CONFLICT_MESSAGE % {
-            enum: enum_name,
-            klass: self.name,
-            type: 'instance',
-            method: method_name,
-            source: 'another enum'
-          }
+          raise_conflict_error(enum_name, method_name, source: 'another enum')
         end
       end
+
+      def raise_conflict_error(enum_name, method_name, type: 'instance', source: 'Active Record')
+        raise ArgumentError, ENUM_CONFLICT_MESSAGE % {
+          enum: enum_name,
+          klass: self.name,
+          type: type,
+          method: method_name,
+          source: source
+        }
+      end
   end
 end
diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
index fc28ab585f..533c86a6a9 100644
--- a/activerecord/lib/active_record/errors.rb
+++ b/activerecord/lib/active_record/errors.rb
@@ -7,8 +7,10 @@ module ActiveRecord
   end
 
   # Raised when the single-table inheritance mechanism fails to locate the subclass
-  # (for example due to improper usage of column that +inheritance_column+ points to).
-  class SubclassNotFound < ActiveRecordError #:nodoc:
+  # (for example due to improper usage of column that
+  # {ActiveRecord::Base.inheritance_column}[rdoc-ref:ModelSchema::ClassMethods#inheritance_column]
+  # points to).
+  class SubclassNotFound < ActiveRecordError
   end
 
   # Raised when an object assigned to an association has an incorrect type.
@@ -40,27 +42,40 @@ module ActiveRecord
   class AdapterNotFound < ActiveRecordError
   end
 
-  # Raised when connection to the database could not been established (for
-  # example when +connection=+ is given a nil object).
+  # Raised when connection to the database could not been established (for example when
+  # {ActiveRecord::Base.connection=}[rdoc-ref:ConnectionHandling#connection]
+  # is given a nil object).
   class ConnectionNotEstablished < ActiveRecordError
   end
 
-  # Raised when Active Record cannot find record by given id or set of ids.
+  # Raised when Active Record cannot find a record by given id or set of ids.
   class RecordNotFound < ActiveRecordError
+    attr_reader :model, :primary_key, :id
+
+    def initialize(message = nil, model = nil, primary_key = nil, id = nil)
+      @primary_key = primary_key
+      @model = model
+      @id = id
+
+      super(message)
+    end
   end
 
-  # Raised by ActiveRecord::Base.save! and ActiveRecord::Base.create! methods when record cannot be
-  # saved because record is invalid.
+  # Raised by {ActiveRecord::Base#save!}[rdoc-ref:Persistence#save!] and
+  # {ActiveRecord::Base.create!}[rdoc-ref:Persistence::ClassMethods#create!]
+  # methods when a record is invalid and can not be saved.
   class RecordNotSaved < ActiveRecordError
     attr_reader :record
 
-    def initialize(message, record = nil)
+    def initialize(message = nil, record = nil)
       @record = record
       super(message)
     end
   end
 
-  # Raised by ActiveRecord::Base.destroy! when a call to destroy would return false.
+  # Raised by {ActiveRecord::Base#destroy!}[rdoc-ref:Persistence#destroy!]
+  # when a call to {#destroy}[rdoc-ref:Persistence#destroy!]
+  # would return false.
   #
   #   begin
   #     complex_operation_that_internally_calls_destroy!
@@ -71,9 +86,9 @@ module ActiveRecord
   class RecordNotDestroyed < ActiveRecordError
     attr_reader :record
 
-    def initialize(record)
+    def initialize(message = nil, record = nil)
       @record = record
-      super()
+      super(message)
     end
   end
 
@@ -83,14 +98,14 @@ module ActiveRecord
   class StatementInvalid < ActiveRecordError
     attr_reader :original_exception
 
-    def initialize(message, original_exception = nil)
-      super(message)
+    def initialize(message = nil, original_exception = nil)
       @original_exception = original_exception
+      super(message)
     end
   end
 
   # Defunct wrapper class kept for compatibility.
-  # +StatementInvalid+ wraps the original exception now.
+  # StatementInvalid wraps the original exception now.
   class WrappedDatabaseException < StatementInvalid
   end
 
@@ -103,8 +118,8 @@ module ActiveRecord
   end
 
   # Raised when number of bind variables in statement given to +:condition+ key
-  # (for example, when using +find+ method) does not match number of expected
-  # values supplied.
+  # (for example, when using {ActiveRecord::Base.find}[rdoc-ref:FinderMethods#find] method)
+  # does not match number of expected values supplied.
   #
   # For example, when there are two placeholders with only one value supplied:
   #
@@ -125,16 +140,22 @@ module ActiveRecord
   class StaleObjectError < ActiveRecordError
     attr_reader :record, :attempted_action
 
-    def initialize(record, attempted_action)
-      super("Attempted to #{attempted_action} a stale object: #{record.class.name}")
-      @record = record
-      @attempted_action = attempted_action
+    def initialize(record = nil, attempted_action = nil)
+      if record && attempted_action
+        @record = record
+        @attempted_action = attempted_action
+        super("Attempted to #{attempted_action} a stale object: #{record.class.name}.")
+      else
+        super("Stale object error.")
+      end
     end
 
   end
 
   # Raised when association is being configured improperly or user tries to use
-  # offset and limit together with +has_many+ or +has_and_belongs_to_many+
+  # offset and limit together with
+  # {ActiveRecord::Base.has_many}[rdoc-ref:Associations::ClassMethods#has_many] or
+  # {ActiveRecord::Base.has_and_belongs_to_many}[rdoc-ref:Associations::ClassMethods#has_and_belongs_to_many]
   # associations.
   class ConfigurationError < ActiveRecordError
   end
@@ -143,9 +164,10 @@ module ActiveRecord
   class ReadOnlyRecord < ActiveRecordError
   end
 
-  # ActiveRecord::Transactions::ClassMethods.transaction uses this exception
-  # to distinguish a deliberate rollback from other exceptional situations.
-  # Normally, raising an exception will cause the +transaction+ method to rollback
+  # {ActiveRecord::Base.transaction}[rdoc-ref:Transactions::ClassMethods#transaction]
+  # uses this exception to distinguish a deliberate rollback from other exceptional situations.
+  # Normally, raising an exception will cause the
+  # {.transaction}[rdoc-ref:Transactions::ClassMethods#transaction] method to rollback
   # the database transaction *and* pass on the exception. But if you raise an
   # ActiveRecord::Rollback exception, then the database transaction will be rolled back,
   # without passing on the exception.
@@ -179,38 +201,29 @@ module ActiveRecord
   end
 
   # Raised when unknown attributes are supplied via mass assignment.
-  class UnknownAttributeError < NoMethodError
-
-    attr_reader :record, :attribute
-
-    def initialize(record, attribute)
-      @record = record
-      @attribute = attribute.to_s
-      super("unknown attribute '#{attribute}' for #{@record.class}.")
-    end
-
-  end
+  UnknownAttributeError = ActiveModel::UnknownAttributeError
 
   # Raised when an error occurred while doing a mass assignment to an attribute through the
-  # +attributes=+ method. The exception has an +attribute+ property that is the name of the
-  # offending attribute.
+  # {ActiveRecord::Base#attributes=}[rdoc-ref:AttributeAssignment#attributes=] method.
+  # The exception has an +attribute+ property that is the name of the offending attribute.
   class AttributeAssignmentError < ActiveRecordError
     attr_reader :exception, :attribute
 
-    def initialize(message, exception, attribute)
+    def initialize(message = nil, exception = nil, attribute = nil)
       super(message)
       @exception = exception
       @attribute = attribute
     end
   end
 
-  # Raised when there are multiple errors while doing a mass assignment through the +attributes+
+  # Raised when there are multiple errors while doing a mass assignment through the
+  # {ActiveRecord::Base#attributes=}[rdoc-ref:AttributeAssignment#attributes=]
   # method. The exception has an +errors+ property that contains an array of AttributeAssignmentError
   # objects, each corresponding to the error while assigning to an attribute.
   class MultiparameterAssignmentErrors < ActiveRecordError
     attr_reader :errors
 
-    def initialize(errors)
+    def initialize(errors = nil)
       @errors = errors
     end
   end
@@ -219,11 +232,16 @@ module ActiveRecord
   class UnknownPrimaryKey < ActiveRecordError
     attr_reader :model
 
-    def initialize(model)
-      super("Unknown primary key for table #{model.table_name} in model #{model}.")
-      @model = model
+    def initialize(model = nil, description = nil)
+      if model
+        message = "Unknown primary key for table #{model.table_name} in model #{model}."
+        message += "\n#{description}" if description
+        @model = model
+        super(message)
+      else
+        super("Unknown primary key.")
+      end
     end
-
   end
 
   # Raised when a relation cannot be mutated because it's already loaded.
diff --git a/activerecord/lib/active_record/explain_registry.rb b/activerecord/lib/active_record/explain_registry.rb
index f5cd57e075..b652932f9c 100644
--- a/activerecord/lib/active_record/explain_registry.rb
+++ b/activerecord/lib/active_record/explain_registry.rb
@@ -7,7 +7,7 @@ module ActiveRecord
   #
   # returns the collected queries local to the current thread.
   #
-  # See the documentation of <tt>ActiveSupport::PerThreadRegistry</tt>
+  # See the documentation of ActiveSupport::PerThreadRegistry
   # for further details.
   class ExplainRegistry # :nodoc:
     extend ActiveSupport::PerThreadRegistry
diff --git a/activerecord/lib/active_record/explain_subscriber.rb b/activerecord/lib/active_record/explain_subscriber.rb
index 6a49936644..90bcf5a205 100644
--- a/activerecord/lib/active_record/explain_subscriber.rb
+++ b/activerecord/lib/active_record/explain_subscriber.rb
@@ -14,12 +14,12 @@ module ActiveRecord
     end
 
     # SCHEMA queries cannot be EXPLAINed, also we do not want to run EXPLAIN on
-    # our own EXPLAINs now matter how loopingly beautiful that would be.
+    # our own EXPLAINs no matter how loopingly beautiful that would be.
     #
     # On the other hand, we want to monitor the performance of our real database
     # queries, not the performance of the access to the query cache.
     IGNORED_PAYLOADS = %w(SCHEMA EXPLAIN CACHE)
-    EXPLAINED_SQLS = /\A\s*(select|update|delete|insert)\b/i
+    EXPLAINED_SQLS = /\A\s*(with|select|update|delete|insert)\b/i
     def ignore_payload?(payload)
       payload[:exception] || IGNORED_PAYLOADS.include?(payload[:name]) || payload[:sql] !~ EXPLAINED_SQLS
     end
diff --git a/activerecord/lib/active_record/fixture_set/file.rb b/activerecord/lib/active_record/fixture_set/file.rb
index 8132310c91..f969556c50 100644
--- a/activerecord/lib/active_record/fixture_set/file.rb
+++ b/activerecord/lib/active_record/fixture_set/file.rb
@@ -17,24 +17,39 @@ module ActiveRecord
 
       def initialize(file)
         @file = file
-        @rows = nil
       end
 
       def each(&block)
         rows.each(&block)
       end
 
+      def model_class
+        config_row['model_class']
+      end
 
       private
         def rows
-          return @rows if @rows
+          @rows ||= raw_rows.reject { |fixture_name, _| fixture_name == '_fixture' }
+        end
+
+        def config_row
+          @config_row ||= begin
+            row = raw_rows.find { |fixture_name, _| fixture_name == '_fixture' }
+            if row
+              row.last
+            else
+              {'model_class': nil}
+            end
+          end
+        end
 
-          begin
+        def raw_rows
+          @raw_rows ||= begin
             data = YAML.load(render(IO.read(@file)))
+            data ? validate(data).to_a : []
           rescue ArgumentError, Psych::SyntaxError => error
             raise Fixture::FormatError, "a YAML error occurred parsing #{@file}. Please note that YAML must be consistently indented using spaces. Tabs are not allowed. Please have a look at http://www.yaml.org/faq.html\nThe exact error was:\n  #{error.class}: #{error}", error.backtrace
           end
-          @rows = data ? validate(data).to_a : []
         end
 
         def render(content)
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 10e9be20b5..17e7c828b9 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -1,6 +1,7 @@
 require 'erb'
 require 'yaml'
 require 'zlib'
+require 'set'
 require 'active_support/dependencies'
 require 'active_support/core_ext/digest/uuid'
 require 'active_record/fixture_set/file'
@@ -88,7 +89,7 @@ module ActiveRecord
   #   end
   #
   # In order to use these methods to access fixtured data within your testcases, you must specify one of the
-  # following in your <tt>ActiveSupport::TestCase</tt>-derived class:
+  # following in your ActiveSupport::TestCase-derived class:
   #
   # - to fully enable instantiated fixtures (enable alternate methods #1 and #2 above)
   #     self.use_instantiated_fixtures = true
@@ -109,7 +110,7 @@ module ActiveRecord
   #   <% 1.upto(1000) do |i| %>
   #   fix_<%= i %>:
   #     id: <%= i %>
-  #     name: guy_<%= 1 %>
+  #     name: guy_<%= i %>
   #   <% end %>
   #
   # This will create 1000 very simple fixtures.
@@ -123,7 +124,7 @@ module ActiveRecord
   #
   # Helper methods defined in a fixture will not be available in other fixtures, to prevent against
   # unwanted inter-test dependencies. Methods used by multiple fixtures should be defined in a module
-  # that is included in <tt>ActiveRecord::FixtureSet.context_class</tt>.
+  # that is included in ActiveRecord::FixtureSet.context_class.
   #
   # - define a helper method in `test_helper.rb`
   #     module FixtureFileHelpers
@@ -131,20 +132,20 @@ module ActiveRecord
   #         Digest::SHA2.hexdigest(File.read(Rails.root.join('test/fixtures', path)))
   #       end
   #     end
-  #     ActiveRecord::FixtureSet.context_class.send :include, FixtureFileHelpers
+  #     ActiveRecord::FixtureSet.context_class.include FixtureFileHelpers
   #
   # - use the helper method in a fixture
   #     photo:
   #       name: kitten.png
   #       sha: <%= file_sha 'files/kitten.png' %>
   #
-  # = Transactional Fixtures
+  # = Transactional Tests
   #
   # Test cases can use begin+rollback to isolate their changes to the database instead of having to
   # delete+insert for every test case.
   #
   #   class FooTest < ActiveSupport::TestCase
-  #     self.use_transactional_fixtures = true
+  #     self.use_transactional_tests = true
   #
   #     test "godzilla" do
   #       assert !Foo.all.empty?
@@ -158,14 +159,14 @@ module ActiveRecord
   #   end
   #
   # If you preload your test database with all fixture data (probably in the rake task) and use
-  # transactional fixtures, then you may omit all fixtures declarations in your test cases since
+  # transactional tests, then you may omit all fixtures declarations in your test cases since
   # all the data's already there and every case rolls back its changes.
   #
   # In order to use instantiated fixtures with preloaded data, set +self.pre_loaded_fixtures+ to
   # true. This will provide access to fixture data for every table that has been loaded through
   # fixtures (depending on the value of +use_instantiated_fixtures+).
   #
-  # When *not* to use transactional fixtures:
+  # When *not* to use transactional tests:
   #
   # 1. You're testing whether a transaction works correctly. Nested transactions don't commit until
   #    all parent transactions commit, particularly, the fixtures transaction which is begun in setup
@@ -394,6 +395,20 @@ module ActiveRecord
   #     <<: *DEFAULTS
   #
   # Any fixture labeled "DEFAULTS" is safely ignored.
+  #
+  # == Configure the fixture model class
+  #
+  # It's possible to set the fixture's model class directly in the YAML file.
+  # This is helpful when fixtures are loaded outside tests and
+  # +set_fixture_class+ is not available (e.g.
+  # when running <tt>rake db:fixtures:load</tt>).
+  #
+  #   _fixture:
+  #     model_class: User
+  #   david:
+  #     name: David
+  #
+  # Any fixtures labeled "_fixture" are safely ignored.
   class FixtureSet
     #--
     # An instance of FixtureSet is normally stored in a single YAML file and
@@ -521,12 +536,16 @@ module ActiveRecord
           update_all_loaded_fixtures fixtures_map
 
           connection.transaction(:requires_new => true) do
+            deleted_tables = Set.new
             fixture_sets.each do |fs|
               conn = fs.model_class.respond_to?(:connection) ? fs.model_class.connection : connection
               table_rows = fs.table_rows
 
               table_rows.each_key do |table|
-                conn.delete "DELETE FROM #{conn.quote_table_name(table)}", 'Fixture Delete'
+                unless deleted_tables.include? table
+                  conn.delete "DELETE FROM #{conn.quote_table_name(table)}", 'Fixture Delete'
+                end
+                deleted_tables << table
               end
 
               table_rows.each do |fixture_set_name, rows|
@@ -534,12 +553,10 @@ module ActiveRecord
                   conn.insert_fixture(row, fixture_set_name)
                 end
               end
-            end
 
-            # Cap primary key sequences to max(pk).
-            if connection.respond_to?(:reset_pk_sequence!)
-              fixture_sets.each do |fs|
-                connection.reset_pk_sequence!(fs.table_name)
+              # Cap primary key sequences to max(pk).
+              if conn.respond_to?(:reset_pk_sequence!)
+                conn.reset_pk_sequence!(fs.table_name)
               end
             end
           end
@@ -575,21 +592,16 @@ module ActiveRecord
       @name     = name
       @path     = path
       @config   = config
-      @model_class = nil
 
-      if class_name.is_a?(Class) # TODO: Should be an AR::Base type class, or any?
-        @model_class = class_name
-      else
-        @model_class = class_name.safe_constantize if class_name
-      end
+      self.model_class = class_name
+
+      @fixtures = read_fixture_files(path)
 
       @connection  = connection
 
       @table_name = ( model_class.respond_to?(:table_name) ?
                       model_class.table_name :
                       self.class.default_fixture_table_name(name, config) )
-
-      @fixtures = read_fixture_files path, @model_class
     end
 
     def [](x)
@@ -612,7 +624,6 @@ module ActiveRecord
     # a list of rows to insert to that table.
     def table_rows
       now = config.default_timezone == :utc ? Time.now.utc : Time.now
-      now = now.to_s(:db)
 
       # allow a standard key to be used for doing defaults in YAML
       fixtures.delete('DEFAULTS')
@@ -641,6 +652,13 @@ module ActiveRecord
             row[primary_key_name] = ActiveRecord::FixtureSet.identify(label, primary_key_type)
           end
 
+          # Resolve enums
+          model_class.defined_enums.each do |name, values|
+            if row.include?(name)
+              row[name] = values.fetch(row[name], row[name])
+            end
+          end
+
           # If STI is used, find the correct subclass for association reflection
           reflection_class =
             if row.include?(inheritance_column_name)
@@ -661,7 +679,7 @@ module ActiveRecord
                   row[association.foreign_type] = $1
                 end
 
-                fk_type = association.active_record.columns_hash[fk_name].type
+                fk_type = reflection_class.type_for_attribute(fk_name).type
                 row[fk_name] = ActiveRecord::FixtureSet.identify(value, fk_type)
               end
             when :has_many
@@ -691,7 +709,7 @@ module ActiveRecord
       end
 
       def primary_key_type
-        @association.klass.column_types[@association.klass.primary_key].type
+        @association.klass.type_for_attribute(@association.klass.primary_key).type
       end
     end
 
@@ -703,6 +721,10 @@ module ActiveRecord
       def lhs_key
         @association.through_reflection.foreign_key
       end
+
+      def join_table
+        @association.through_reflection.table_name
+      end
     end
 
     private
@@ -711,7 +733,7 @@ module ActiveRecord
       end
 
       def primary_key_type
-        @primary_key_type ||= model_class && model_class.column_types[model_class.primary_key].type
+        @primary_key_type ||= model_class && model_class.type_for_attribute(model_class.primary_key).type
       end
 
       def add_join_records(rows, row, association)
@@ -748,13 +770,25 @@ module ActiveRecord
         @column_names ||= @connection.columns(@table_name).collect(&:name)
       end
 
-      def read_fixture_files(path, model_class)
+      def model_class=(class_name)
+        if class_name.is_a?(Class) # TODO: Should be an AR::Base type class, or any?
+          @model_class = class_name
+        else
+          @model_class = class_name.safe_constantize if class_name
+        end
+      end
+
+      # Loads the fixtures from the YAML file at +path+.
+      # If the file sets the +model_class+ and current instance value is not set,
+      # it uses the file value.
+      def read_fixture_files(path)
         yaml_files = Dir["#{path}/{**,*}/*.yml"].select { |f|
           ::File.file?(f)
         } + [yaml_file_path(path)]
 
         yaml_files.each_with_object({}) do |file, fixtures|
           FixtureSet::File.open(file) do |fh|
+            self.model_class ||= fh.model_class if fh.model_class
             fh.each do |fixture_name, row|
               fixtures[fixture_name] = ActiveRecord::Fixture.new(row, model_class)
             end
@@ -814,12 +848,12 @@ module ActiveRecord
   module TestFixtures
     extend ActiveSupport::Concern
 
-    def before_setup
+    def before_setup # :nodoc:
       setup_fixtures
       super
     end
 
-    def after_teardown
+    def after_teardown # :nodoc:
       super
       teardown_fixtures
     end
@@ -828,13 +862,15 @@ module ActiveRecord
       class_attribute :fixture_path, :instance_writer => false
       class_attribute :fixture_table_names
       class_attribute :fixture_class_names
+      class_attribute :use_transactional_tests
       class_attribute :use_transactional_fixtures
       class_attribute :use_instantiated_fixtures # true, false, or :no_instances
       class_attribute :pre_loaded_fixtures
       class_attribute :config
 
+      singleton_class.deprecate 'use_transactional_fixtures=' => 'use use_transactional_tests= instead'
+
       self.fixture_table_names = []
-      self.use_transactional_fixtures = true
       self.use_instantiated_fixtures = false
       self.pre_loaded_fixtures = false
       self.config = ActiveRecord::Base
@@ -842,6 +878,16 @@ module ActiveRecord
       self.fixture_class_names = Hash.new do |h, fixture_set_name|
         h[fixture_set_name] = ActiveRecord::FixtureSet.default_fixture_model_name(fixture_set_name, self.config)
       end
+
+      silence_warnings do
+        define_singleton_method :use_transactional_tests do
+          if use_transactional_fixtures.nil?
+            true
+          else
+            use_transactional_fixtures
+          end
+        end
+      end
     end
 
     module ClassMethods
@@ -912,13 +958,13 @@ module ActiveRecord
     end
 
     def run_in_transaction?
-      use_transactional_fixtures &&
+      use_transactional_tests &&
         !self.class.uses_transaction?(method_name)
     end
 
     def setup_fixtures(config = ActiveRecord::Base)
-      if pre_loaded_fixtures && !use_transactional_fixtures
-        raise RuntimeError, 'pre_loaded_fixtures requires use_transactional_fixtures'
+      if pre_loaded_fixtures && !use_transactional_tests
+        raise RuntimeError, 'pre_loaded_fixtures requires use_transactional_tests'
       end
 
       @fixture_cache = {}
diff --git a/activerecord/lib/active_record/inheritance.rb b/activerecord/lib/active_record/inheritance.rb
index fd1e22349b..c26842014d 100644
--- a/activerecord/lib/active_record/inheritance.rb
+++ b/activerecord/lib/active_record/inheritance.rb
@@ -82,7 +82,7 @@ module ActiveRecord
       # Returns the class descending directly from ActiveRecord::Base, or
       # an abstract class, if any, in the inheritance hierarchy.
       #
-      # If A extends AR::Base, A.base_class will return A. If B descends from A
+      # If A extends ActiveRecord::Base, A.base_class will return A. If B descends from A
       # through some arbitrarily deep hierarchy, B.base_class will return A.
       #
       # If B < A and C < B and if A is an abstract_class then both B.base_class
@@ -192,20 +192,22 @@ module ActiveRecord
       # If this is a StrongParameters hash, and access to inheritance_column is not permitted,
       # this will ignore the inheritance column and return nil
       def subclass_from_attributes?(attrs)
-        columns_hash.include?(inheritance_column) && attrs.is_a?(Hash)
+        attribute_names.include?(inheritance_column) && attrs.is_a?(Hash)
       end
 
       def subclass_from_attributes(attrs)
         subclass_name = attrs.with_indifferent_access[inheritance_column]
 
-        if subclass_name.present? && subclass_name != self.name
-          subclass = subclass_name.safe_constantize
+        if subclass_name.present?
+          subclass = find_sti_class(subclass_name)
 
-          unless descendants.include?(subclass)
-            raise ActiveRecord::SubclassNotFound.new("Invalid single-table inheritance type: #{subclass_name} is not a subclass of #{name}")
-          end
+          if subclass.name != self.name
+            unless descendants.include?(subclass)
+              raise ActiveRecord::SubclassNotFound.new("Invalid single-table inheritance type: #{subclass.name} is not a subclass of #{name}")
+            end
 
-          subclass
+            subclass
+          end
         end
       end
     end
diff --git a/activerecord/lib/active_record/integration.rb b/activerecord/lib/active_record/integration.rb
index 15b2f65dcb..466c8509a4 100644
--- a/activerecord/lib/active_record/integration.rb
+++ b/activerecord/lib/active_record/integration.rb
@@ -10,12 +10,12 @@ module ActiveRecord
       # Indicates the format used to generate the timestamp in the cache key.
       # Accepts any of the symbols in <tt>Time::DATE_FORMATS</tt>.
       #
-      # This is +:nsec+, by default.
+      # This is +:usec+, by default.
       class_attribute :cache_timestamp_format, :instance_writer => false
-      self.cache_timestamp_format = :nsec
+      self.cache_timestamp_format = :usec
     end
 
-    # Returns a String, which Action Pack uses for constructing an URL to this
+    # Returns a String, which Action Pack uses for constructing a URL to this
     # object. The default implementation returns this record's id as a String,
     # or nil if this record's unsaved.
     #
@@ -84,7 +84,7 @@ module ActiveRecord
       # Values longer than 20 characters will be truncated. The value
       # is truncated word by word.
       #
-      #   user = User.find_by(name: 'David HeinemeierHansson')
+      #   user = User.find_by(name: 'David Heinemeier Hansson')
       #   user.id         # => 125
       #   user_path(user) # => "/users/125-david"
       #
diff --git a/activerecord/lib/active_record/legacy_yaml_adapter.rb b/activerecord/lib/active_record/legacy_yaml_adapter.rb
new file mode 100644
index 0000000000..89dee58423
--- /dev/null
+++ b/activerecord/lib/active_record/legacy_yaml_adapter.rb
@@ -0,0 +1,46 @@
+module ActiveRecord
+  module LegacyYamlAdapter
+    def self.convert(klass, coder)
+      return coder unless coder.is_a?(Psych::Coder)
+
+      case coder["active_record_yaml_version"]
+      when 1 then coder
+      else
+        if coder["attributes"].is_a?(AttributeSet)
+          Rails420.convert(klass, coder)
+        else
+          Rails41.convert(klass, coder)
+        end
+      end
+    end
+
+    module Rails420
+      def self.convert(klass, coder)
+        attribute_set = coder["attributes"]
+
+        klass.attribute_names.each do |attr_name|
+          attribute = attribute_set[attr_name]
+          if attribute.type.is_a?(Delegator)
+            type_from_klass = klass.type_for_attribute(attr_name)
+            attribute_set[attr_name] = attribute.with_type(type_from_klass)
+          end
+        end
+
+        coder
+      end
+    end
+
+    module Rails41
+      def self.convert(klass, coder)
+        attributes = klass.attributes_builder
+          .build_from_database(coder["attributes"])
+        new_record = coder["attributes"][klass.primary_key].blank?
+
+        {
+          "attributes" => attributes,
+          "new_record" => new_record,
+        }
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/locale/en.yml b/activerecord/lib/active_record/locale/en.yml
index b1fbd38622..0b35027b2b 100644
--- a/activerecord/lib/active_record/locale/en.yml
+++ b/activerecord/lib/active_record/locale/en.yml
@@ -7,6 +7,7 @@ en:
   # Default error messages
   errors:
     messages:
+      required: "must exist"
       taken: "has already been taken"
 
   # Active Record models configuration
@@ -15,8 +16,8 @@ en:
       messages:
         record_invalid: "Validation failed: %{errors}"
         restrict_dependent_destroy:
-          one: "Cannot delete record because a dependent %{record} exists"
-          many: "Cannot delete record because dependent %{record} exist"
+          has_one: "Cannot delete record because a dependent %{record} exists"
+          has_many: "Cannot delete record because dependent %{record} exist"
         # Append your own errors here or at the model/attributes scope.
 
       # You can define own errors for models or model attributes.
diff --git a/activerecord/lib/active_record/locking/optimistic.rb b/activerecord/lib/active_record/locking/optimistic.rb
index 6f2b65c137..2336d23a1c 100644
--- a/activerecord/lib/active_record/locking/optimistic.rb
+++ b/activerecord/lib/active_record/locking/optimistic.rb
@@ -22,7 +22,7 @@ module ActiveRecord
     #   p1.save
     #
     #   p2.first_name = "should fail"
-    #   p2.save # Raises a ActiveRecord::StaleObjectError
+    #   p2.save # Raises an ActiveRecord::StaleObjectError
     #
     # Optimistic locking will also check for stale data when objects are destroyed. Example:
     #
@@ -32,7 +32,7 @@ module ActiveRecord
     #   p1.first_name = "Michael"
     #   p1.save
     #
-    #   p2.destroy # Raises a ActiveRecord::StaleObjectError
+    #   p2.destroy # Raises an ActiveRecord::StaleObjectError
     #
     # You're then responsible for dealing with the conflict by rescuing the exception and either rolling back, merging,
     # or otherwise apply the business logic needed to resolve the conflict.
@@ -93,7 +93,7 @@ module ActiveRecord
               self.class.primary_key => id,
               lock_col => previous_lock_value,
             ).update_all(
-              attribute_names.map do |name|
+              attributes_for_update(attribute_names).map do |name|
                 [name, _read_attribute(name)]
               end.to_h
             )
@@ -144,7 +144,7 @@ module ActiveRecord
 
         # Set the column to use for optimistic locking. Defaults to +lock_version+.
         def locking_column=(value)
-          clear_caches_calculated_from_columns
+          reload_schema_from_cache
           @locking_column = value.to_s
         end
 
@@ -184,8 +184,8 @@ module ActiveRecord
       end
     end
 
-    class LockingType < SimpleDelegator # :nodoc:
-      def type_cast_from_database(value)
+    class LockingType < DelegateClass(Type::Value) # :nodoc:
+      def deserialize(value)
         # `nil` *should* be changed to 0
         super.to_i
       end
diff --git a/activerecord/lib/active_record/locking/pessimistic.rb b/activerecord/lib/active_record/locking/pessimistic.rb
index ff7102d35b..8ecdf76b72 100644
--- a/activerecord/lib/active_record/locking/pessimistic.rb
+++ b/activerecord/lib/active_record/locking/pessimistic.rb
@@ -51,7 +51,7 @@ module ActiveRecord
     #   end
     #
     # Database-specific information on row locking:
-    #   MySQL: http://dev.mysql.com/doc/refman/5.1/en/innodb-locking-reads.html
+    #   MySQL: http://dev.mysql.com/doc/refman/5.7/en/innodb-locking-reads.html
     #   PostgreSQL: http://www.postgresql.org/docs/current/interactive/sql-select.html#SQL-FOR-UPDATE-SHARE
     module Pessimistic
       # Obtain a row lock on this record. Reloads the record to obtain the requested
diff --git a/activerecord/lib/active_record/log_subscriber.rb b/activerecord/lib/active_record/log_subscriber.rb
index a5c7279db9..b63caa4473 100644
--- a/activerecord/lib/active_record/log_subscriber.rb
+++ b/activerecord/lib/active_record/log_subscriber.rb
@@ -20,24 +20,21 @@ module ActiveRecord
       @odd = false
     end
 
-    def render_bind(column, value)
-      if column
-        if column.binary? && value
-          # This specifically deals with the PG adapter that casts bytea columns into a Hash.
-          value = value[:value] if value.is_a?(Hash)
-          value = "<#{value.bytesize} bytes of binary data>"
-        end
-
-        [column.name, value]
+    def render_bind(attribute)
+      value = if attribute.type.binary? && attribute.value
+        "<#{attribute.value.bytesize} bytes of binary data>"
       else
-        [nil, value]
+        attribute.value_for_database
       end
+
+      [attribute.name, value]
     end
 
     def sql(event)
-      self.class.runtime += event.duration
       return unless logger.debug?
 
+      self.class.runtime += event.duration
+
       payload = event.payload
 
       return if IGNORE_PAYLOAD_NAMES.include?(payload[:name])
@@ -47,23 +44,44 @@ module ActiveRecord
       binds = nil
 
       unless (payload[:binds] || []).empty?
-        binds = "  " + payload[:binds].map { |col,v|
-          render_bind(col, v)
-        }.inspect
+        binds = "  " + payload[:binds].map { |attr| render_bind(attr) }.inspect
       end
 
-      if odd?
-        name = color(name, CYAN, true)
-        sql  = color(sql, nil, true)
-      else
-        name = color(name, MAGENTA, true)
-      end
+      name = colorize_payload_name(name, payload[:name])
+      sql  = color(sql, sql_color(sql), true)
 
       debug "  #{name}  #{sql}#{binds}"
     end
 
-    def odd?
-      @odd = !@odd
+    private
+
+    def colorize_payload_name(name, payload_name)
+      if payload_name.blank? || payload_name == "SQL" # SQL vs Model Load/Exists
+        color(name, MAGENTA, true)
+      else
+        color(name, CYAN, true)
+      end
+    end
+
+    def sql_color(sql)
+      case sql
+        when /\A\s*rollback/mi
+          RED
+        when /\s*.*?select .*for update/mi, /\A\s*lock/mi
+          WHITE
+        when /\A\s*select/i
+          BLUE
+        when /\A\s*insert/i
+          GREEN
+        when /\A\s*update/i
+          YELLOW
+        when /\A\s*delete/i
+          RED
+        when /transaction\s*\Z/i
+          CYAN
+        else
+          MAGENTA
+      end
     end
 
     def logger
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 46f4794010..c8b96b8de0 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -9,40 +9,128 @@ module ActiveRecord
     end
   end
 
-  # Exception that can be raised to stop migrations from going backwards.
+  # Exception that can be raised to stop migrations from being rolled back.
+  # For example the following migration is not reversible.
+  # Rolling back this migration will raise an ActiveRecord::IrreversibleMigration error.
+  #
+  #   class IrreversibleMigrationExample < ActiveRecord::Migration
+  #     def change
+  #       create_table :distributors do |t|
+  #         t.string :zipcode
+  #       end
+  #
+  #       execute <<-SQL
+  #         ALTER TABLE distributors
+  #           ADD CONSTRAINT zipchk
+  #             CHECK (char_length(zipcode) = 5) NO INHERIT;
+  #       SQL
+  #     end
+  #   end
+  #
+  # There are two ways to mitigate this problem.
+  #
+  # 1. Define <tt>#up</tt> and <tt>#down</tt> methods instead of <tt>#change</tt>:
+  #
+  #  class ReversibleMigrationExample < ActiveRecord::Migration
+  #    def up
+  #      create_table :distributors do |t|
+  #        t.string :zipcode
+  #      end
+  #
+  #      execute <<-SQL
+  #        ALTER TABLE distributors
+  #          ADD CONSTRAINT zipchk
+  #            CHECK (char_length(zipcode) = 5) NO INHERIT;
+  #      SQL
+  #    end
+  #
+  #    def down
+  #      execute <<-SQL
+  #        ALTER TABLE distributors
+  #          DROP CONSTRAINT zipchk
+  #      SQL
+  #
+  #      drop_table :distributors
+  #    end
+  #  end
+  #
+  # 2. Use the #reversible method in <tt>#change</tt> method:
+  #
+  #   class ReversibleMigrationExample < ActiveRecord::Migration
+  #     def change
+  #       create_table :distributors do |t|
+  #         t.string :zipcode
+  #       end
+  #
+  #       reversible do |dir|
+  #         dir.up do
+  #           execute <<-SQL
+  #             ALTER TABLE distributors
+  #               ADD CONSTRAINT zipchk
+  #                 CHECK (char_length(zipcode) = 5) NO INHERIT;
+  #           SQL
+  #         end
+  #
+  #         dir.down do
+  #           execute <<-SQL
+  #             ALTER TABLE distributors
+  #               DROP CONSTRAINT zipchk
+  #           SQL
+  #         end
+  #       end
+  #     end
+  #   end
   class IrreversibleMigration < MigrationError
   end
 
   class DuplicateMigrationVersionError < MigrationError#:nodoc:
-    def initialize(version)
-      super("Multiple migrations have the version number #{version}")
+    def initialize(version = nil)
+      if version
+        super("Multiple migrations have the version number #{version}.")
+      else
+        super("Duplicate migration version error.")
+      end
     end
   end
 
   class DuplicateMigrationNameError < MigrationError#:nodoc:
-    def initialize(name)
-      super("Multiple migrations have the name #{name}")
+    def initialize(name = nil)
+      if name
+        super("Multiple migrations have the name #{name}.")
+      else
+        super("Duplicate migration name.")
+      end
     end
   end
 
   class UnknownMigrationVersionError < MigrationError #:nodoc:
-    def initialize(version)
-      super("No migration with version number #{version}")
+    def initialize(version = nil)
+      if version
+        super("No migration with version number #{version}.")
+      else
+        super("Unknown migration version.")
+      end
     end
   end
 
   class IllegalMigrationNameError < MigrationError#:nodoc:
-    def initialize(name)
-      super("Illegal name for migration file: #{name}\n\t(only lower case letters, numbers, and '_' allowed)")
+    def initialize(name = nil)
+      if name
+        super("Illegal name for migration file: #{name}\n\t(only lower case letters, numbers, and '_' allowed).")
+      else
+        super("Illegal name for migration.")
+      end
     end
   end
 
   class PendingMigrationError < MigrationError#:nodoc:
-    def initialize
-      if defined?(Rails.env)
-        super("Migrations are pending. To resolve this issue, run:\n\n\tbin/rake db:migrate RAILS_ENV=#{::Rails.env}")
+    def initialize(message = nil)
+      if !message && defined?(Rails.env)
+        super("Migrations are pending. To resolve this issue, run:\n\n\tbin/rake db:migrate RAILS_ENV=#{::Rails.env}.")
+      elsif !message
+        super("Migrations are pending. To resolve this issue, run:\n\n\tbin/rake db:migrate.")
       else
-        super("Migrations are pending. To resolve this issue, run:\n\n\tbin/rake db:migrate")
+        super
       end
     end
   end
@@ -106,17 +194,18 @@ module ActiveRecord
   #
   # == Available transformations
   #
+  # === Creation
+  #
+  # * <tt>create_join_table(table_1, table_2, options)</tt>: Creates a join
+  #   table having its name as the lexical order of the first two
+  #   arguments. See
+  #   ActiveRecord::ConnectionAdapters::SchemaStatements#create_join_table for
+  #   details.
   # * <tt>create_table(name, options)</tt>: Creates a table called +name+ and
   #   makes the table object available to a block that can then add columns to it,
   #   following the same format as +add_column+. See example above. The options hash
   #   is for fragments like "DEFAULT CHARSET=UTF-8" that are appended to the create
   #   table definition.
-  # * <tt>drop_table(name)</tt>: Drops the table called +name+.
-  # * <tt>change_table(name, options)</tt>: Allows to make column alterations to
-  #   the table called +name+. It makes the table object available to a block that
-  #   can then add/remove columns, indexes or foreign keys to it.
-  # * <tt>rename_table(old_name, new_name)</tt>: Renames the table called +old_name+
-  #   to +new_name+.
   # * <tt>add_column(table_name, column_name, type, options)</tt>: Adds a new column
   #   to the table called +table_name+
   #   named +column_name+ specified to be one of the following types:
@@ -127,21 +216,59 @@ module ActiveRecord
   #   Other options include <tt>:limit</tt> and <tt>:null</tt> (e.g.
   #   <tt>{ limit: 50, null: false }</tt>) -- see
   #   ActiveRecord::ConnectionAdapters::TableDefinition#column for details.
-  # * <tt>rename_column(table_name, column_name, new_column_name)</tt>: Renames
-  #   a column but keeps the type and content.
-  # * <tt>change_column(table_name, column_name, type, options)</tt>:  Changes
-  #   the column to a different type using the same parameters as add_column.
-  # * <tt>remove_column(table_name, column_name, type, options)</tt>: Removes the column
-  #   named +column_name+ from the table called +table_name+.
+  # * <tt>add_foreign_key(from_table, to_table, options)</tt>: Adds a new
+  #   foreign key. +from_table+ is the table with the key column, +to_table+ contains
+  #   the referenced primary key.
   # * <tt>add_index(table_name, column_names, options)</tt>: Adds a new index
   #   with the name of the column. Other options include
   #   <tt>:name</tt>, <tt>:unique</tt> (e.g.
   #   <tt>{ name: 'users_name_index', unique: true }</tt>) and <tt>:order</tt>
   #   (e.g. <tt>{ order: { name: :desc } }</tt>).
-  # * <tt>remove_index(table_name, column: column_name)</tt>: Removes the index
-  #   specified by +column_name+.
+  # * <tt>add_reference(:table_name, :reference_name)</tt>: Adds a new column
+  #   +reference_name_id+ by default an integer. See
+  #   ActiveRecord::ConnectionAdapters::SchemaStatements#add_reference for details.
+  # * <tt>add_timestamps(table_name, options)</tt>: Adds timestamps (+created_at+
+  #   and +updated_at+) columns to +table_name+.
+  #
+  # === Modification
+  #
+  # * <tt>change_column(table_name, column_name, type, options)</tt>:  Changes
+  #   the column to a different type using the same parameters as add_column.
+  # * <tt>change_column_default(table_name, column_name, default)</tt>: Sets a
+  #   default value for +column_name+ definded by +default+ on +table_name+.
+  # * <tt>change_column_null(table_name, column_name, null, default = nil)</tt>:
+  #   Sets or removes a +NOT NULL+ constraint on +column_name+. The +null+ flag
+  #   indicates whether the value can be +NULL+. See
+  #   ActiveRecord::ConnectionAdapters::SchemaStatements#change_column_null for
+  #   details.
+  # * <tt>change_table(name, options)</tt>: Allows to make column alterations to
+  #   the table called +name+. It makes the table object available to a block that
+  #   can then add/remove columns, indexes or foreign keys to it.
+  # * <tt>rename_column(table_name, column_name, new_column_name)</tt>: Renames
+  #   a column but keeps the type and content.
+  # * <tt>rename_index(table_name, old_name, new_name)</tt>: Renames an index.
+  # * <tt>rename_table(old_name, new_name)</tt>: Renames the table called +old_name+
+  #   to +new_name+.
+  #
+  # === Deletion
+  #
+  # * <tt>drop_table(name)</tt>: Drops the table called +name+.
+  # * <tt>drop_join_table(table_1, table_2, options)</tt>: Drops the join table
+  #   specified by the given arguments.
+  # * <tt>remove_column(table_name, column_name, type, options)</tt>: Removes the column
+  #   named +column_name+ from the table called +table_name+.
+  # * <tt>remove_columns(table_name, *column_names)</tt>: Removes the given
+  #   columns from the table definition.
+  # * <tt>remove_foreign_key(from_table, options_or_to_table)</tt>: Removes the
+  #   given foreign key from the table called +table_name+.
+  # * <tt>remove_index(table_name, column: column_names)</tt>: Removes the index
+  #   specified by +column_names+.
   # * <tt>remove_index(table_name, name: index_name)</tt>: Removes the index
   #   specified by +index_name+.
+  # * <tt>remove_reference(table_name, ref_name, options)</tt>: Removes the
+  #   reference(s) on +table_name+ specified by +ref_name+.
+  # * <tt>remove_timestamps(table_name, options)</tt>: Removes the timestamp
+  #   columns (+created_at+ and +updated_at+) from the table definition.
   #
   # == Irreversible transformations
   #
@@ -165,10 +292,10 @@ module ActiveRecord
   #
   #   rails generate migration add_fieldname_to_tablename fieldname:string
   #
-  # This will generate the file <tt>timestamp_add_fieldname_to_tablename</tt>, which will look like this:
+  # This will generate the file <tt>timestamp_add_fieldname_to_tablename.rb</tt>, which will look like this:
   #   class AddFieldnameToTablename < ActiveRecord::Migration
   #     def change
-  #       add_column :tablenames, :field, :string
+  #       add_column :tablenames, :fieldname, :string
   #     end
   #   end
   #
@@ -275,21 +402,6 @@ module ActiveRecord
   # The phrase "Updating salaries..." would then be printed, along with the
   # benchmark for the block when the block completes.
   #
-  # == About the schema_migrations table
-  #
-  # Rails versions 2.0 and prior used to create a table called
-  # <tt>schema_info</tt> when using migrations. This table contained the
-  # version of the schema as of the last applied migration.
-  #
-  # Starting with Rails 2.1, the <tt>schema_info</tt> table is
-  # (automatically) replaced by the <tt>schema_migrations</tt> table, which
-  # contains the version numbers of all the migrations applied.
-  #
-  # As a result, it is now possible to add migration files that are numbered
-  # lower than the current schema version: when migrating up, those
-  # never-applied "interleaved" migrations will be automatically applied, and
-  # when migrating down, never-applied "interleaved" migrations will be skipped.
-  #
   # == Timestamped Migrations
   #
   # By default, Rails generates migrations that look like:
@@ -307,9 +419,8 @@ module ActiveRecord
   #
   # == Reversible Migrations
   #
-  # Starting with Rails 3.1, you will be able to define reversible migrations.
   # Reversible migrations are migrations that know how to go +down+ for you.
-  # You simply supply the +up+ logic, and the Migration system will figure out
+  # You simply supply the +up+ logic, and the Migration system figures out
   # how to execute the down commands for you.
   #
   # To define a reversible migration, define the +change+ method in your
@@ -389,13 +500,14 @@ module ActiveRecord
       attr_accessor :delegate # :nodoc:
       attr_accessor :disable_ddl_transaction # :nodoc:
 
+      # Raises <tt>ActiveRecord::PendingMigrationError</tt> error if any migrations are pending.
       def check_pending!(connection = Base.connection)
         raise ActiveRecord::PendingMigrationError if ActiveRecord::Migrator.needs_migration?(connection)
       end
 
       def load_schema_if_pending!
         if ActiveRecord::Migrator.needs_migration? || !ActiveRecord::Migrator.any_migrations?
-          # Roundrip to Rake to allow plugins to hook into database initialization.
+          # Roundtrip to Rake to allow plugins to hook into database initialization.
           FileUtils.cd Rails.root do
             current_config = Base.connection_config
             Base.clear_all_connections!
@@ -421,7 +533,10 @@ module ActiveRecord
         new.migrate direction
       end
 
-      # Disable DDL transactions for this migration.
+      # Disable the transaction wrapping this migration.
+      # You can still create your own transactions even after calling #disable_ddl_transaction!
+      #
+      # For more details read the {"Transactional Migrations" section above}[rdoc-ref:Migration].
       def disable_ddl_transaction!
         @disable_ddl_transaction = true
       end
@@ -468,7 +583,7 @@ module ActiveRecord
     # Or equivalently, if +TenderloveMigration+ is defined as in the
     # documentation for Migration:
     #
-    #   require_relative '2012121212_tenderlove_migration'
+    #   require_relative '20121212123456_tenderlove_migration'
     #
     #   class FixupTLMigration < ActiveRecord::Migration
     #     def change
@@ -484,13 +599,13 @@ module ActiveRecord
     def revert(*migration_classes)
       run(*migration_classes.reverse, revert: true) unless migration_classes.empty?
       if block_given?
-        if @connection.respond_to? :revert
-          @connection.revert { yield }
+        if connection.respond_to? :revert
+          connection.revert { yield }
         else
-          recorder = CommandRecorder.new(@connection)
+          recorder = CommandRecorder.new(connection)
           @connection = recorder
           suppress_messages do
-            @connection.revert { yield }
+            connection.revert { yield }
           end
           @connection = recorder.delegate
           recorder.commands.each do |cmd, args, block|
@@ -501,7 +616,7 @@ module ActiveRecord
     end
 
     def reverting?
-      @connection.respond_to?(:reverting) && @connection.reverting
+      connection.respond_to?(:reverting) && connection.reverting
     end
 
     class ReversibleBlockHelper < Struct.new(:reverting) # :nodoc:
@@ -558,7 +673,7 @@ module ActiveRecord
         revert { run(*migration_classes, direction: dir, revert: true) }
       else
         migration_classes.each do |migration_class|
-          migration_class.new.exec_migration(@connection, dir)
+          migration_class.new.exec_migration(connection, dir)
         end
       end
     end
@@ -650,10 +765,11 @@ module ActiveRecord
       arg_list = arguments.map(&:inspect) * ', '
 
       say_with_time "#{method}(#{arg_list})" do
-        unless @connection.respond_to? :revert
+        unless connection.respond_to? :revert
           unless arguments.empty? || [:execute, :enable_extension, :disable_extension].include?(method)
             arguments[0] = proper_table_name(arguments.first, table_name_options)
-            if [:rename_table, :add_foreign_key].include?(method)
+            if [:rename_table, :add_foreign_key].include?(method) ||
+              (method == :remove_foreign_key && !arguments.second.is_a?(Hash))
               arguments[1] = proper_table_name(arguments.second, table_name_options)
             end
           end
@@ -728,7 +844,9 @@ module ActiveRecord
       end
     end
 
-    def table_name_options(config = ActiveRecord::Base)
+    # Builds a hash for use in ActiveRecord::Migration#proper_table_name using
+    # the Active Record object's table_name prefix and suffix
+    def table_name_options(config = ActiveRecord::Base) #:nodoc:
       {
         table_name_prefix: config.table_name_prefix,
         table_name_suffix: config.table_name_suffix
@@ -820,7 +938,7 @@ module ActiveRecord
         new(:up, migrations, target_version).migrate
       end
 
-      def down(migrations_paths, target_version = nil, &block)
+      def down(migrations_paths, target_version = nil)
         migrations = migrations(migrations_paths)
         migrations.select! { |m| yield m } if block_given?
 
@@ -859,24 +977,16 @@ module ActiveRecord
         migrations(migrations_paths).any?
       end
 
-      def last_version
-        last_migration.version
-      end
-
       def last_migration #:nodoc:
         migrations(migrations_paths).last || NullMigration.new
       end
 
       def migrations_paths
         @migrations_paths ||= ['db/migrate']
-        # just to not break things if someone uses: migration_path = some_string
+        # just to not break things if someone uses: migrations_path = some_string
         Array(@migrations_paths)
       end
 
-      def migrations_path
-        migrations_paths.first
-      end
-
       def migrations(paths)
         paths = Array(paths)
 
diff --git a/activerecord/lib/active_record/migration/command_recorder.rb b/activerecord/lib/active_record/migration/command_recorder.rb
index 36256415df..0fa665c7e0 100644
--- a/activerecord/lib/active_record/migration/command_recorder.rb
+++ b/activerecord/lib/active_record/migration/command_recorder.rb
@@ -5,15 +5,36 @@ module ActiveRecord
     # knows how to invert the following commands:
     #
     # * add_column
+    # * add_foreign_key
     # * add_index
+    # * add_reference
     # * add_timestamps
-    # * create_table
+    # * change_column
+    # * change_column_default (must supply a :from and :to option)
+    # * change_column_null
     # * create_join_table
+    # * create_table
+    # * disable_extension
+    # * drop_join_table
+    # * drop_table (must supply a block)
+    # * enable_extension
+    # * remove_column (must supply a type)
+    # * remove_columns (must specify at least one column name or more)
+    # * remove_foreign_key (must supply a second table)
+    # * remove_index
+    # * remove_reference
     # * remove_timestamps
     # * rename_column
     # * rename_index
     # * rename_table
     class CommandRecorder
+      ReversibleAndIrreversibleMethods = [:create_table, :create_join_table, :rename_table, :add_column, :remove_column,
+        :rename_index, :rename_column, :add_index, :remove_index, :add_timestamps, :remove_timestamps,
+        :change_column_default, :add_reference, :remove_reference, :transaction,
+        :drop_join_table, :drop_table, :execute_block, :enable_extension, :disable_extension,
+        :change_column, :execute, :remove_columns, :change_column_null,
+        :add_foreign_key, :remove_foreign_key
+      ]
       include JoinTable
 
       attr_accessor :commands, :delegate, :reverting
@@ -41,7 +62,7 @@ module ActiveRecord
         @reverting = !@reverting
       end
 
-      # record +command+. +command+ should be a method name and arguments.
+      # Record +command+. +command+ should be a method name and arguments.
       # For example:
       #
       #   recorder.record(:method_name, [:arg1, :arg2])
@@ -62,7 +83,12 @@ module ActiveRecord
       # invert the +command+.
       def inverse_of(command, args, &block)
         method = :"invert_#{command}"
-        raise IrreversibleMigration unless respond_to?(method, true)
+        raise IrreversibleMigration, <<-MSG.strip_heredoc unless respond_to?(method, true)
+          This migration uses #{command}, which is not automatically reversible.
+          To make the migration reversible you can either:
+          1. Define #up and #down methods in place of the #change method.
+          2. Use the #reversible method to define reversible behavior.
+        MSG
         send(method, args, &block)
       end
 
@@ -70,14 +96,7 @@ module ActiveRecord
         super || delegate.respond_to?(*args)
       end
 
-      [:create_table, :create_join_table, :rename_table, :add_column, :remove_column,
-        :rename_index, :rename_column, :add_index, :remove_index, :add_timestamps, :remove_timestamps,
-        :change_column_default, :add_reference, :remove_reference, :transaction,
-        :drop_join_table, :drop_table, :execute_block, :enable_extension,
-        :change_column, :execute, :remove_columns, :change_column_null,
-        :add_foreign_key, :remove_foreign_key
-       # irreversible methods need to be here too
-      ].each do |method|
+      ReversibleAndIrreversibleMethods.each do |method|
         class_eval <<-EOV, __FILE__, __LINE__ + 1
           def #{method}(*args, &block)          # def create_table(*args, &block)
             record(:"#{method}", args, &block)  #   record(:create_table, args, &block)
@@ -151,19 +170,31 @@ module ActiveRecord
       end
 
       def invert_remove_index(args)
-        table, options = *args
-
-        unless options && options.is_a?(Hash) && options[:column]
-          raise ActiveRecord::IrreversibleMigration, "remove_index is only reversible if given a :column option."
+        table, options_or_column = *args
+        if (options = options_or_column).is_a?(Hash)
+          unless options[:column]
+            raise ActiveRecord::IrreversibleMigration, "remove_index is only reversible if given a :column option."
+          end
+          options = options.dup
+          [:add_index, [table, options.delete(:column), options]]
+        elsif (column = options_or_column).present?
+          [:add_index, [table, column]]
         end
-
-        options = options.dup
-        [:add_index, [table, options.delete(:column), options]]
       end
 
       alias :invert_add_belongs_to :invert_add_reference
       alias :invert_remove_belongs_to :invert_remove_reference
 
+      def invert_change_column_default(args)
+        table, column, options = *args
+
+        unless options && options.is_a?(Hash) && options.has_key?(:from) && options.has_key?(:to)
+          raise ActiveRecord::IrreversibleMigration, "change_column_default is only reversible if given a :from and :to option."
+        end
+
+        [:change_column_default, [table, column, from: options[:to], to: options[:from]]]
+      end
+
       def invert_change_column_null(args)
         args[2] = !args[2]
         [:change_column_null, args]
@@ -184,6 +215,16 @@ module ActiveRecord
         [:remove_foreign_key, [from_table, options]]
       end
 
+      def invert_remove_foreign_key(args)
+        from_table, to_table, remove_options = args
+        raise ActiveRecord::IrreversibleMigration, "remove_foreign_key is only reversible if given a second table" if to_table.nil? || to_table.is_a?(Hash)
+
+        reversed_args = [from_table, to_table]
+        reversed_args << remove_options if remove_options
+
+        [:add_foreign_key, reversed_args]
+      end
+
       # Forwards any missing method call to the \target.
       def method_missing(method, *args, &block)
         if @delegate.respond_to?(method)
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 641512d323..a9bd094a66 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -50,6 +50,13 @@ module ActiveRecord
       class_attribute :pluralize_table_names, instance_writer: false
       self.pluralize_table_names = true
 
+      ##
+      # :singleton-method:
+      # Accessor for the list of columns names the model should ignore. Ignored columns won't have attribute
+      # accessors defined, and won't be referenced in SQL queries.
+      class_attribute :ignored_columns, instance_accessor: false
+      self.ignored_columns = [].freeze
+
       self.inheritance_column = 'type'
 
       delegate :type_for_attribute, to: :class
@@ -111,17 +118,6 @@ module ActiveRecord
       #   class Mouse < ActiveRecord::Base
       #     self.table_name = "mice"
       #   end
-      #
-      # Alternatively, you can override the table_name method to define your
-      # own computation. (Possibly using <tt>super</tt> to manipulate the default
-      # table name.) Example:
-      #
-      #   class Post < ActiveRecord::Base
-      #     def self.table_name
-      #       "special_" + super
-      #     end
-      #   end
-      #   Post.table_name # => "special_posts"
       def table_name
         reset_table_name unless defined?(@table_name)
         @table_name
@@ -132,9 +128,6 @@ module ActiveRecord
       #   class Project < ActiveRecord::Base
       #     self.table_name = "project"
       #   end
-      #
-      # You can also just define your own <tt>self.table_name</tt> method; see
-      # the documentation for ActiveRecord::Base#table_name.
       def table_name=(value)
         value = value && value.to_s
 
@@ -227,32 +220,41 @@ module ActiveRecord
 
       # Indicates whether the table associated with this class exists
       def table_exists?
-        connection.schema_cache.table_exists?(table_name)
+        connection.schema_cache.data_source_exists?(table_name)
       end
 
       def attributes_builder # :nodoc:
-        @attributes_builder ||= AttributeSet::Builder.new(column_types, primary_key)
+        @attributes_builder ||= AttributeSet::Builder.new(attribute_types, primary_key)
       end
 
-      def column_types # :nodoc:
-        @column_types ||= columns_hash.transform_values(&:cast_type).tap do |h|
-          h.default = Type::Value.new
-        end
+      def columns_hash # :nodoc:
+        load_schema
+        @columns_hash
+      end
+
+      def columns
+        load_schema
+        @columns ||= columns_hash.values
+      end
+
+      def attribute_types # :nodoc:
+        load_schema
+        @attribute_types ||= Hash.new(Type::Value.new)
       end
 
       def type_for_attribute(attr_name) # :nodoc:
-        column_types[attr_name]
+        attribute_types[attr_name]
       end
 
       # Returns a hash where the keys are column names and the values are
-      # default values when instantiating the AR object for this table.
+      # default values when instantiating the Active Record object for this table.
       def column_defaults
+        load_schema
         _default_attributes.to_hash
       end
 
       def _default_attributes # :nodoc:
-        @default_attributes ||= attributes_builder.build_from_database(
-          raw_default_values)
+        @default_attributes ||= AttributeSet.new({})
       end
 
       # Returns an array of column names as strings.
@@ -295,19 +297,50 @@ module ActiveRecord
       def reset_column_information
         connection.clear_cache!
         undefine_attribute_methods
-        connection.schema_cache.clear_table_cache!(table_name) if table_exists?
+        connection.schema_cache.clear_data_source_cache!(table_name)
 
-        @arel_engine        = nil
-        @arel_table         = nil
-        @column_names       = nil
-        @column_types       = nil
-        @content_columns    = nil
-        @default_attributes = nil
-        @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column
+        reload_schema_from_cache
       end
 
       private
 
+      def schema_loaded?
+        defined?(@columns_hash) && @columns_hash
+      end
+
+      def load_schema
+        unless schema_loaded?
+          load_schema!
+        end
+      end
+
+      def load_schema!
+        @columns_hash = connection.schema_cache.columns_hash(table_name).except(*ignored_columns)
+        @columns_hash.each do |name, column|
+          warn_if_deprecated_type(column)
+          define_attribute(
+            name,
+            connection.lookup_cast_type_from_column(column),
+            default: column.default,
+            user_provided_default: false
+          )
+        end
+      end
+
+      def reload_schema_from_cache
+        @arel_engine = nil
+        @arel_table = nil
+        @column_names = nil
+        @attribute_types = nil
+        @content_columns = nil
+        @default_attributes = nil
+        @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column
+        @attributes_builder = nil
+        @columns = nil
+        @columns_hash = nil
+        @attribute_names = nil
+      end
+
       # Guesses the table name, but does not decorate it with prefix and suffix information.
       def undecorated_table_name(class_name = base_class.name)
         table_name = class_name.to_s.demodulize.underscore
@@ -332,8 +365,26 @@ module ActiveRecord
         end
       end
 
-      def raw_default_values
-        columns_hash.transform_values(&:default)
+      def warn_if_deprecated_type(column)
+        return if attributes_to_define_after_schema_loads.key?(column.name)
+        if column.respond_to?(:oid) && column.sql_type.start_with?("point")
+          if column.array?
+            array_arguments = ", array: true"
+          else
+            array_arguments = ""
+          end
+          ActiveSupport::Deprecation.warn(<<-WARNING.strip_heredoc)
+            The behavior of the `:point` type will be changing in Rails 5.1 to
+            return a `Point` object, rather than an `Array`. If you'd like to
+            keep the old behavior, you can add this line to #{self.name}:
+
+              attribute :#{column.name}, :legacy_point#{array_arguments}
+
+            If you'd like the new behavior today, you can add this line:
+
+              attribute :#{column.name}, :rails_5_1_point#{array_arguments}
+          WARNING
+        end
       end
     end
   end
diff --git a/activerecord/lib/active_record/nested_attributes.rb b/activerecord/lib/active_record/nested_attributes.rb
index 846e1162a9..c5a1488588 100644
--- a/activerecord/lib/active_record/nested_attributes.rb
+++ b/activerecord/lib/active_record/nested_attributes.rb
@@ -147,8 +147,8 @@ module ActiveRecord
     #     has_many :posts
     #     accepts_nested_attributes_for :posts, reject_if: :reject_posts
     #
-    #     def reject_posts(attributed)
-    #       attributed['title'].blank?
+    #     def reject_posts(attributes)
+    #       attributes['title'].blank?
     #     end
     #   end
     #
@@ -166,6 +166,11 @@ module ActiveRecord
     #   member.posts.first.title # => '[UPDATED] An, as of yet, undisclosed awesome Ruby documentation browser!'
     #   member.posts.second.title # => '[UPDATED] other post'
     #
+    # However, the above applies if the parent model is being updated as well.
+    # For example, If you wanted to create a +member+ named _joe_ and wanted to
+    # update the +posts+ at the same time, that would give an
+    # ActiveRecord::RecordNotFound error.
+    #
     # By default the associated records are protected from being destroyed. If
     # you want to destroy any of the associated records through the attributes
     # hash, you have to enable it first using the <tt>:allow_destroy</tt>
@@ -208,7 +213,7 @@ module ActiveRecord
     #
     # Passing attributes for an associated collection in the form of a hash
     # of hashes can be used with hashes generated from HTTP/HTML parameters,
-    # where there maybe no natural way to submit an array of hashes.
+    # where there may be no natural way to submit an array of hashes.
     #
     # === Saving
     #
@@ -312,7 +317,7 @@ module ActiveRecord
         attr_names.each do |association_name|
           if reflection = _reflect_on_association(association_name)
             reflection.autosave = true
-            add_autosave_association_callbacks(reflection)
+            define_autosave_validation_callbacks(reflection)
 
             nested_attributes_options = self.nested_attributes_options.dup
             nested_attributes_options[association_name.to_sym] = options
@@ -381,6 +386,9 @@ module ActiveRecord
     # then the existing record will be marked for destruction.
     def assign_nested_attributes_for_one_to_one_association(association_name, attributes)
       options = self.nested_attributes_options[association_name]
+      if attributes.respond_to?(:permitted?)
+        attributes = attributes.to_h
+      end
       attributes = attributes.with_indifferent_access
       existing_record = send(association_name)
 
@@ -437,6 +445,9 @@ module ActiveRecord
     #   ])
     def assign_nested_attributes_for_collection_association(association_name, attributes_collection)
       options = self.nested_attributes_options[association_name]
+      if attributes_collection.respond_to?(:permitted?)
+        attributes_collection = attributes_collection.to_h
+      end
 
       unless attributes_collection.is_a?(Hash) || attributes_collection.is_a?(Array)
         raise ArgumentError, "Hash or Array expected, got #{attributes_collection.class.name} (#{attributes_collection.inspect})"
@@ -463,6 +474,9 @@ module ActiveRecord
       end
 
       attributes_collection.each do |attributes|
+        if attributes.respond_to?(:permitted?)
+          attributes = attributes.to_h
+        end
         attributes = attributes.with_indifferent_access
 
         if attributes['id'].blank?
@@ -521,7 +535,7 @@ module ActiveRecord
 
     # Determines if a hash contains a truthy _destroy key.
     def has_destroy_flag?(hash)
-      Type::Boolean.new.type_cast_from_user(hash['_destroy'])
+      Type::Boolean.new.cast(hash['_destroy'])
     end
 
     # Determines if a new record should be rejected by checking
@@ -547,7 +561,9 @@ module ActiveRecord
     end
 
     def raise_nested_attributes_record_not_found!(association_name, record_id)
-      raise RecordNotFound, "Couldn't find #{self.class._reflect_on_association(association_name).klass.name} with ID=#{record_id} for #{self.class.name} with ID=#{id}"
+      model = self.class._reflect_on_association(association_name).klass.name
+      raise RecordNotFound.new("Couldn't find #{model} with ID=#{record_id} for #{self.class.name} with ID=#{id}",
+                               model, 'id', record_id)
     end
   end
 end
diff --git a/activerecord/lib/active_record/null_relation.rb b/activerecord/lib/active_record/null_relation.rb
index b406da14dc..0b500346bc 100644
--- a/activerecord/lib/active_record/null_relation.rb
+++ b/activerecord/lib/active_record/null_relation.rb
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 module ActiveRecord
   module NullRelation # :nodoc:
     def exec_queries
@@ -14,7 +12,7 @@ module ActiveRecord
       0
     end
 
-    def update_all(_updates, _conditions = nil, _options = {})
+    def update_all(_updates)
       0
     end
 
@@ -30,10 +28,18 @@ module ActiveRecord
       true
     end
 
+    def none?
+      true
+    end
+
     def any?
       false
     end
 
+    def one?
+      false
+    end
+
     def many?
       false
     end
@@ -72,8 +78,12 @@ module ActiveRecord
       end
     end
 
-    def exists?(_id = false)
+    def exists?(_conditions = :none)
       false
     end
+
+    def or(other)
+      other.spawn
+    end
   end
 end
diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
index 6306a25745..94316d5249 100644
--- a/activerecord/lib/active_record/persistence.rb
+++ b/activerecord/lib/active_record/persistence.rb
@@ -1,5 +1,5 @@
 module ActiveRecord
-  # = Active Record Persistence
+  # = Active Record \Persistence
   module Persistence
     extend ActiveSupport::Concern
 
@@ -96,7 +96,8 @@ module ActiveRecord
     # Returns true if the record is persisted, i.e. it's not a new record and it was
     # not destroyed, otherwise returns false.
     def persisted?
-      !(new_record? || destroyed?)
+      sync_with_transaction_state
+      !(@new_record || @destroyed)
     end
 
     # Saves the model.
@@ -105,7 +106,7 @@ module ActiveRecord
     # the existing record gets updated.
     #
     # By default, save always run validations. If any of them fail the action
-    # is cancelled and +save+ returns +false+. However, if you supply
+    # is cancelled and #save returns +false+. However, if you supply
     # validate: false, validations are bypassed altogether. See
     # ActiveRecord::Validations for more information.
     #
@@ -131,7 +132,7 @@ module ActiveRecord
     # If the model is new, a record gets created in the database, otherwise
     # the existing record gets updated.
     #
-    # With <tt>save!</tt> validations always run. If any of them fail
+    # With #save! validations always run. If any of them fail
     # ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations
     # for more information.
     #
@@ -147,7 +148,7 @@ module ActiveRecord
     # Attributes marked as readonly are silently ignored if the record is
     # being updated.
     def save!(*args)
-      create_or_update(*args) || raise(RecordNotSaved.new(nil, self))
+      create_or_update(*args) || raise(RecordNotSaved.new("Failed to save the record", self))
     end
 
     # Deletes the record in the database and freezes this instance to
@@ -157,7 +158,7 @@ module ActiveRecord
     # The row is simply removed with an SQL +DELETE+ statement on the
     # record's primary key, and no callbacks are executed.
     #
-    # Note that this will also delete records marked as <tt>readonly?</tt>.
+    # Note that this will also delete records marked as {#readonly?}[rdoc-ref:Core#readonly?].
     #
     # To enforce the object's +before_destroy+ and +after_destroy+
     # callbacks or any <tt>:dependent</tt> association
@@ -178,6 +179,7 @@ module ActiveRecord
     def destroy
       raise ReadOnlyRecord, "#{self.class} is marked as readonly" if readonly?
       destroy_associations
+      self.class.connection.add_transaction_record(self)
       destroy_row if persisted?
       @destroyed = true
       freeze
@@ -191,7 +193,7 @@ module ActiveRecord
     # and #destroy! raises ActiveRecord::RecordNotDestroyed.
     # See ActiveRecord::Callbacks for further details.
     def destroy!
-      destroy || raise(ActiveRecord::RecordNotDestroyed, self)
+      destroy || _raise_record_not_destroyed
     end
 
     # Returns an instance of the specified +klass+ with the attributes of the
@@ -203,18 +205,21 @@ module ActiveRecord
     # instance using the companies/company partial instead of clients/client.
     #
     # Note: The new instance will share a link to the same attributes as the original class.
-    # So any change to the attributes in either instance will affect the other.
+    # Therefore the sti column value will still be the same.
+    # Any change to the attributes on either instance will affect both instances.
+    # If you want to change the sti column as well, use #becomes! instead.
     def becomes(klass)
       became = klass.new
       became.instance_variable_set("@attributes", @attributes)
-      became.instance_variable_set("@changed_attributes", @changed_attributes) if defined?(@changed_attributes)
+      became.instance_variable_set("@mutation_tracker", @mutation_tracker) if defined?(@mutation_tracker)
+      became.instance_variable_set("@changed_attributes", attributes_changed_by_setter)
       became.instance_variable_set("@new_record", new_record?)
       became.instance_variable_set("@destroyed", destroyed?)
       became.instance_variable_set("@errors", errors)
       became
     end
 
-    # Wrapper around +becomes+ that also changes the instance's sti column value.
+    # Wrapper around #becomes that also changes the instance's sti column value.
     # This is especially useful if you want to persist the changed class in your
     # database.
     #
@@ -234,19 +239,19 @@ module ActiveRecord
     # This is especially useful for boolean flags on existing records. Also note that
     #
     # * Validation is skipped.
-    # * Callbacks are invoked.
+    # * \Callbacks are invoked.
     # * updated_at/updated_on column is updated if that column is available.
     # * Updates all the attributes that are dirty in this object.
     #
-    # This method raises an +ActiveRecord::ActiveRecordError+  if the
+    # This method raises an ActiveRecord::ActiveRecordError  if the
     # attribute is marked as readonly.
     #
-    # See also +update_column+.
+    # See also #update_column.
     def update_attribute(name, value)
       name = name.to_s
       verify_readonly_attribute(name)
-      send("#{name}=", value)
-      save(validate: false)
+      public_send("#{name}=", value)
+      save(validate: false) if changed?
     end
 
     # Updates the attributes of the model from the passed-in hash and saves the
@@ -263,7 +268,7 @@ module ActiveRecord
 
     alias update_attributes update
 
-    # Updates its receiver just like +update+ but calls <tt>save!</tt> instead
+    # Updates its receiver just like #update but calls #save! instead
     # of +save+, so an exception is raised if the record is invalid.
     def update!(attributes)
       # The following transaction covers any possible database side-effects of the
@@ -290,11 +295,11 @@ module ActiveRecord
     # the database, but take into account that in consequence the regular update
     # procedures are totally bypassed. In particular:
     #
-    # * Validations are skipped.
-    # * Callbacks are skipped.
+    # * \Validations are skipped.
+    # * \Callbacks are skipped.
     # * +updated_at+/+updated_on+ are not updated.
     #
-    # This method raises an +ActiveRecord::ActiveRecordError+ when called on new
+    # This method raises an ActiveRecord::ActiveRecordError when called on new
     # objects, or when at least one of the attributes is marked as readonly.
     def update_columns(attributes)
       raise ActiveRecordError, "cannot update a new record" if new_record?
@@ -322,29 +327,31 @@ module ActiveRecord
       self
     end
 
-    # Wrapper around +increment+ that saves the record. This method differs from
+    # Wrapper around #increment that saves the record. This method differs from
     # its non-bang version in that it passes through the attribute setter.
     # Saving is not subjected to validation checks. Returns +true+ if the
     # record could be saved.
     def increment!(attribute, by = 1)
-      increment(attribute, by).update_attribute(attribute, self[attribute])
+      increment(attribute, by)
+      change = public_send(attribute) - (attribute_was(attribute.to_s) || 0)
+      self.class.update_counters(id, attribute => change)
+      clear_attribute_change(attribute) # eww
+      self
     end
 
     # Initializes +attribute+ to zero if +nil+ and subtracts the value passed as +by+ (default is 1).
     # The decrement is performed directly on the underlying attribute, no setter is invoked.
     # Only makes sense for number-based attributes. Returns +self+.
     def decrement(attribute, by = 1)
-      self[attribute] ||= 0
-      self[attribute] -= by
-      self
+      increment(attribute, -by)
     end
 
-    # Wrapper around +decrement+ that saves the record. This method differs from
+    # Wrapper around #decrement that saves the record. This method differs from
     # its non-bang version in that it passes through the attribute setter.
     # Saving is not subjected to validation checks. Returns +true+ if the
     # record could be saved.
     def decrement!(attribute, by = 1)
-      decrement(attribute, by).update_attribute(attribute, self[attribute])
+      increment!(attribute, -by)
     end
 
     # Assigns to +attribute+ the boolean opposite of <tt>attribute?</tt>. So
@@ -352,11 +359,11 @@ module ActiveRecord
     # method toggles directly the underlying value without calling any setter.
     # Returns +self+.
     def toggle(attribute)
-      self[attribute] = !send("#{attribute}?")
+      self[attribute] = !public_send("#{attribute}?")
       self
     end
 
-    # Wrapper around +toggle+ that saves the record. This method differs from
+    # Wrapper around #toggle that saves the record. This method differs from
     # its non-bang version in that it passes through the attribute setter.
     # Saving is not subjected to validation checks. Returns +true+ if the
     # record could be saved.
@@ -377,9 +384,9 @@ module ActiveRecord
     #   # => #<Account id: 1, email: 'account@example.com'>
     #
     # Attributes are reloaded from the database, and caches busted, in
-    # particular the associations cache.
+    # particular the associations cache and the QueryCache.
     #
-    # If the record no longer exists in the database <tt>ActiveRecord::RecordNotFound</tt>
+    # If the record no longer exists in the database ActiveRecord::RecordNotFound
     # is raised. Otherwise, in addition to the in-place modification the method
     # returns +self+ for convenience.
     #
@@ -413,8 +420,7 @@ module ActiveRecord
     #   end
     #
     def reload(options = nil)
-      clear_aggregation_cache
-      clear_association_cache
+      self.class.connection.clear_query_cache
 
       fresh_object =
         if options && options[:lock]
@@ -428,19 +434,22 @@ module ActiveRecord
       self
     end
 
-    # Saves the record with the updated_at/on attributes set to the current time.
+    # Saves the record with the updated_at/on attributes set to the current time
+    # or the time specified.
     # Please note that no validation is performed and only the +after_touch+,
     # +after_commit+ and +after_rollback+ callbacks are executed.
     #
+    # This method can be passed attribute names and an optional time argument.
     # If attribute names are passed, they are updated along with updated_at/on
-    # attributes.
+    # attributes. If no time argument is passed, the current time is used as default.
     #
-    #   product.touch                         # updates updated_at/on
+    #   product.touch                         # updates updated_at/on with current time
+    #   product.touch(time: Time.new(2015, 2, 16, 0, 0, 0)) # updates updated_at/on with specified time
     #   product.touch(:designed_at)           # updates the designed_at attribute and updated_at/on
     #   product.touch(:started_at, :ended_at) # updates started_at, ended_at and updated_at/on attributes
     #
-    # If used along with +belongs_to+ then +touch+ will invoke +touch+ method on
-    # associated object.
+    # If used along with {belongs_to}[rdoc-ref:Associations::ClassMethods#belongs_to]
+    # then +touch+ will invoke +touch+ method on associated object.
     #
     #   class Brake < ActiveRecord::Base
     #     belongs_to :car, touch: true
@@ -459,26 +468,38 @@ module ActiveRecord
     #   ball = Ball.new
     #   ball.touch(:updated_at)   # => raises ActiveRecordError
     #
-    def touch(*names)
+    def touch(*names, time: nil)
       raise ActiveRecordError, "cannot touch on a new record object" unless persisted?
 
+      time ||= current_time_from_proper_timezone
       attributes = timestamp_attributes_for_update_in_model
       attributes.concat(names)
 
       unless attributes.empty?
-        current_time = current_time_from_proper_timezone
         changes = {}
 
         attributes.each do |column|
           column = column.to_s
-          changes[column] = write_attribute(column, current_time)
+          changes[column] = write_attribute(column, time)
         end
 
-        changes[self.class.locking_column] = increment_lock if locking_enabled?
-
         clear_attribute_changes(changes.keys)
         primary_key = self.class.primary_key
-        self.class.unscoped.where(primary_key => self[primary_key]).update_all(changes) == 1
+        scope = self.class.unscoped.where(primary_key => _read_attribute(primary_key))
+
+        if locking_enabled?
+          locking_column = self.class.locking_column
+          scope = scope.where(locking_column => _read_attribute(locking_column))
+          changes[locking_column] = increment_lock
+        end
+
+        result = scope.update_all(changes) == 1
+
+        if !result && locking_enabled?
+          raise ActiveRecord::StaleObjectError.new(self, "touch")
+        end
+
+        result
       else
         true
       end
@@ -530,5 +551,12 @@ module ActiveRecord
     def verify_readonly_attribute(name)
       raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
     end
+
+    def _raise_record_not_destroyed
+      @_association_destroy_exception ||= nil
+      raise @_association_destroy_exception || RecordNotDestroyed.new("Failed to destroy the record", self)
+    ensure
+      @_association_destroy_exception = nil
+    end
   end
 end
diff --git a/activerecord/lib/active_record/querying.rb b/activerecord/lib/active_record/querying.rb
index 91c9a0db99..87a1988f2f 100644
--- a/activerecord/lib/active_record/querying.rb
+++ b/activerecord/lib/active_record/querying.rb
@@ -6,8 +6,8 @@ module ActiveRecord
     delegate :find_or_create_by, :find_or_create_by!, :find_or_initialize_by, to: :all
     delegate :find_by, :find_by!, to: :all
     delegate :destroy, :destroy_all, :delete, :delete_all, :update, :update_all, to: :all
-    delegate :find_each, :find_in_batches, to: :all
-    delegate :select, :group, :order, :except, :reorder, :limit, :offset, :joins,
+    delegate :find_each, :find_in_batches, :in_batches, to: :all
+    delegate :select, :group, :order, :except, :reorder, :limit, :offset, :joins, :or,
              :where, :rewhere, :preload, :eager_load, :includes, :from, :lock, :readonly,
              :having, :create_with, :uniq, :distinct, :references, :none, :unscope, to: :all
     delegate :count, :average, :minimum, :maximum, :sum, :calculate, to: :all
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index f1bdbc845c..2744673c12 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -16,11 +16,11 @@ module ActiveRecord
     config.app_generators.orm :active_record, :migration => true,
                                               :timestamps => true
 
-    config.app_middleware.insert_after "::ActionDispatch::Callbacks",
-      "ActiveRecord::QueryCache"
+    config.app_middleware.insert_after ::ActionDispatch::Callbacks,
+      ActiveRecord::QueryCache
 
-    config.app_middleware.insert_after "::ActionDispatch::Callbacks",
-      "ActiveRecord::ConnectionAdapters::ConnectionManagement"
+    config.app_middleware.insert_after ::ActionDispatch::Callbacks,
+      ActiveRecord::ConnectionAdapters::ConnectionManagement
 
     config.action_dispatch.rescue_responses.merge!(
       'ActiveRecord::RecordNotFound'   => :not_found,
@@ -78,8 +78,8 @@ module ActiveRecord
 
     initializer "active_record.migration_error" do
       if config.active_record.delete(:migration_error) == :page_load
-        config.app_middleware.insert_after "::ActionDispatch::Callbacks",
-          "ActiveRecord::Migration::CheckPending"
+        config.app_middleware.insert_after ::ActionDispatch::Callbacks,
+          ActiveRecord::Migration::CheckPending
       end
     end
 
@@ -93,6 +93,7 @@ module ActiveRecord
               cache = Marshal.load File.binread filename
               if cache.version == ActiveRecord::Migrator.current_version
                 self.connection.schema_cache = cache
+                self.connection_pool.schema_cache = cache.dup
               else
                 warn "Ignoring db/schema_cache.dump because it has expired. The current schema version is #{ActiveRecord::Migrator.current_version}, but the one in the cache is #{cache.version}."
               end
@@ -102,6 +103,14 @@ module ActiveRecord
       end
     end
 
+    initializer "active_record.warn_on_records_fetched_greater_than" do
+      if config.active_record.warn_on_records_fetched_greater_than
+        ActiveSupport.on_load(:active_record) do
+          require 'active_record/relation/record_fetch_warning'
+        end
+      end
+    end
+
     initializer "active_record.set_configs" do |app|
       ActiveSupport.on_load(:active_record) do
         app.config.active_record.each do |k,v|
@@ -112,7 +121,7 @@ module ActiveRecord
 
     # This sets the database configuration from Configuration#database_configuration
     # and then establishes the connection.
-    initializer "active_record.initialize_database" do |app|
+    initializer "active_record.initialize_database" do
       ActiveSupport.on_load(:active_record) do
         self.configurations = Rails.application.config.database_configuration
 
@@ -147,8 +156,8 @@ end_warning
       ActiveSupport.on_load(:active_record) do
         ActionDispatch::Reloader.send(hook) do
           if ActiveRecord::Base.connected?
-            ActiveRecord::Base.clear_reloadable_connections!
             ActiveRecord::Base.clear_cache!
+            ActiveRecord::Base.clear_reloadable_connections!
           end
         end
       end
diff --git a/activerecord/lib/active_record/railties/controller_runtime.rb b/activerecord/lib/active_record/railties/controller_runtime.rb
index af4840476c..8727e46cb3 100644
--- a/activerecord/lib/active_record/railties/controller_runtime.rb
+++ b/activerecord/lib/active_record/railties/controller_runtime.rb
@@ -19,7 +19,7 @@ module ActiveRecord
       end
 
       def cleanup_view_runtime
-        if ActiveRecord::Base.connected?
+        if logger.info? && ActiveRecord::Base.connected?
           db_rt_before_render = ActiveRecord::LogSubscriber.reset_runtime
           self.db_runtime = (db_runtime || 0) + db_rt_before_render
           runtime = super
diff --git a/activerecord/lib/active_record/railties/databases.rake b/activerecord/lib/active_record/railties/databases.rake
index 04c2be045d..b6f3695856 100644
--- a/activerecord/lib/active_record/railties/databases.rake
+++ b/activerecord/lib/active_record/railties/databases.rake
@@ -12,7 +12,7 @@ db_namespace = namespace :db do
     end
   end
 
-  desc 'Creates the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:create:all to create all databases in the config). Without RAILS_ENV it defaults to creating the development and test databases.'
+  desc 'Creates the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:create:all to create all databases in the config). Without RAILS_ENV, it defaults to creating the development and test databases.'
   task :create => [:load_config] do
     ActiveRecord::Tasks::DatabaseTasks.create_current
   end
@@ -23,7 +23,7 @@ db_namespace = namespace :db do
     end
   end
 
-  desc 'Drops the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:drop:all to drop all databases in the config). Without RAILS_ENV it defaults to dropping the development and test databases.'
+  desc 'Drops the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:drop:all to drop all databases in the config). Without RAILS_ENV, it defaults to dropping the development and test databases.'
   task :drop => [:load_config] do
     ActiveRecord::Tasks::DatabaseTasks.drop_current
   end
@@ -34,7 +34,7 @@ db_namespace = namespace :db do
     end
   end
 
-  # desc "Empty the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:drop:all to drop all databases in the config). Without RAILS_ENV it defaults to purging the development and test databases."
+  # desc "Empty the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:purge:all to purge all databases in the config). Without RAILS_ENV it defaults to purging the development and test databases."
   task :purge => [:load_config] do
     ActiveRecord::Tasks::DatabaseTasks.purge_current
   end
@@ -42,15 +42,18 @@ db_namespace = namespace :db do
   desc "Migrate the database (options: VERSION=x, VERBOSE=false, SCOPE=blog)."
   task :migrate => [:environment, :load_config] do
     ActiveRecord::Tasks::DatabaseTasks.migrate
-    db_namespace['_dump'].invoke if ActiveRecord::Base.dump_schema_after_migration
+    db_namespace['_dump'].invoke
   end
 
+  # IMPORTANT: This task won't dump the schema if ActiveRecord::Base.dump_schema_after_migration is set to false
   task :_dump do
-    case ActiveRecord::Base.schema_format
-    when :ruby then db_namespace["schema:dump"].invoke
-    when :sql  then db_namespace["structure:dump"].invoke
-    else
-      raise "unknown schema format #{ActiveRecord::Base.schema_format}"
+    if ActiveRecord::Base.dump_schema_after_migration
+      case ActiveRecord::Base.schema_format
+      when :ruby then db_namespace["schema:dump"].invoke
+      when :sql  then db_namespace["structure:dump"].invoke
+      else
+        raise "unknown schema format #{ActiveRecord::Base.schema_format}"
+      end
     end
     # Allow this task to be called as many times as required. An example is the
     # migrate:redo task, which calls other two internally that depend on this one.
@@ -76,7 +79,7 @@ db_namespace = namespace :db do
     task :up => [:environment, :load_config] do
       version = ENV['VERSION'] ? ENV['VERSION'].to_i : nil
       raise 'VERSION is required' unless version
-      ActiveRecord::Migrator.run(:up, ActiveRecord::Migrator.migrations_paths, version)
+      ActiveRecord::Migrator.run(:up, ActiveRecord::Tasks::DatabaseTasks.migrations_paths, version)
       db_namespace['_dump'].invoke
     end
 
@@ -84,7 +87,7 @@ db_namespace = namespace :db do
     task :down => [:environment, :load_config] do
       version = ENV['VERSION'] ? ENV['VERSION'].to_i : nil
       raise 'VERSION is required - To go down one migration, run db:rollback' unless version
-      ActiveRecord::Migrator.run(:down, ActiveRecord::Migrator.migrations_paths, version)
+      ActiveRecord::Migrator.run(:down, ActiveRecord::Tasks::DatabaseTasks.migrations_paths, version)
       db_namespace['_dump'].invoke
     end
 
@@ -96,7 +99,7 @@ db_namespace = namespace :db do
       db_list = ActiveRecord::SchemaMigration.normalized_versions
 
       file_list =
-          ActiveRecord::Migrator.migrations_paths.flat_map do |path|
+          ActiveRecord::Tasks::DatabaseTasks.migrations_paths.flat_map do |path|
             # match "20091231235959_some_name.rb" and "001_some_name.rb" pattern
             Dir.foreach(path).grep(/^(\d{3,})_(.+)\.rb$/) do
               version = ActiveRecord::SchemaMigration.normalize_migration_number($1)
@@ -122,22 +125,19 @@ db_namespace = namespace :db do
   desc 'Rolls the schema back to the previous version (specify steps w/ STEP=n).'
   task :rollback => [:environment, :load_config] do
     step = ENV['STEP'] ? ENV['STEP'].to_i : 1
-    ActiveRecord::Migrator.rollback(ActiveRecord::Migrator.migrations_paths, step)
+    ActiveRecord::Migrator.rollback(ActiveRecord::Tasks::DatabaseTasks.migrations_paths, step)
     db_namespace['_dump'].invoke
   end
 
   # desc 'Pushes the schema to the next version (specify steps w/ STEP=n).'
   task :forward => [:environment, :load_config] do
     step = ENV['STEP'] ? ENV['STEP'].to_i : 1
-    ActiveRecord::Migrator.forward(ActiveRecord::Migrator.migrations_paths, step)
+    ActiveRecord::Migrator.forward(ActiveRecord::Tasks::DatabaseTasks.migrations_paths, step)
     db_namespace['_dump'].invoke
   end
 
   # desc 'Drops and recreates the database from db/schema.rb for the current environment and loads the seeds.'
-  task :reset => [:environment, :load_config] do
-    db_namespace["drop"].invoke
-    db_namespace["setup"].invoke
-  end
+  task :reset => [ 'db:drop', 'db:setup' ]
 
   # desc "Retrieves the charset for the current environment's database"
   task :charset => [:environment, :load_config] do
@@ -159,8 +159,8 @@ db_namespace = namespace :db do
   end
 
   # desc "Raises an error if there are pending migrations"
-  task :abort_if_pending_migrations => :environment do
-    pending_migrations = ActiveRecord::Migrator.open(ActiveRecord::Migrator.migrations_paths).pending_migrations
+  task :abort_if_pending_migrations => [:environment, :load_config] do
+    pending_migrations = ActiveRecord::Migrator.open(ActiveRecord::Tasks::DatabaseTasks.migrations_paths).pending_migrations
 
     if pending_migrations.any?
       puts "You have #{pending_migrations.size} pending #{pending_migrations.size > 1 ? 'migrations:' : 'migration:'}"
@@ -171,17 +171,17 @@ db_namespace = namespace :db do
     end
   end
 
-  desc 'Create the database, load the schema, and initialize with the seed data (use db:reset to also drop the database first)'
+  desc 'Creates the database, loads the schema, and initializes with the seed data (use db:reset to also drop the database first)'
   task :setup => ['db:schema:load_if_ruby', 'db:structure:load_if_sql', :seed]
 
-  desc 'Load the seed data from db/seeds.rb'
+  desc 'Loads the seed data from db/seeds.rb'
   task :seed do
     db_namespace['abort_if_pending_migrations'].invoke
     ActiveRecord::Tasks::DatabaseTasks.load_seed
   end
 
   namespace :fixtures do
-    desc "Load fixtures into the current environment's database. Load specific fixtures using FIXTURES=x,y. Load from subdirectory in test/fixtures using FIXTURES_DIR=z. Specify an alternative path (eg. spec/fixtures) using FIXTURES_PATH=spec/fixtures."
+    desc "Loads fixtures into the current environment's database. Load specific fixtures using FIXTURES=x,y. Load from subdirectory in test/fixtures using FIXTURES_DIR=z. Specify an alternative path (eg. spec/fixtures) using FIXTURES_PATH=spec/fixtures."
     task :load => [:environment, :load_config] do
       require 'active_record/fixtures'
 
@@ -229,7 +229,7 @@ db_namespace = namespace :db do
   end
 
   namespace :schema do
-    desc 'Create a db/schema.rb file that is portable against any DB supported by AR'
+    desc 'Creates a db/schema.rb file that is portable against any DB supported by Active Record'
     task :dump => [:environment, :load_config] do
       require 'active_record/schema_dumper'
       filename = ENV['SCHEMA'] || File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, 'schema.rb')
@@ -239,8 +239,8 @@ db_namespace = namespace :db do
       db_namespace['schema:dump'].reenable
     end
 
-    desc 'Load a schema.rb file into the database'
-    task :load => [:load_config] do
+    desc 'Loads a schema.rb file into the database'
+    task :load => [:environment, :load_config] do
       ActiveRecord::Tasks::DatabaseTasks.load_schema_current(:ruby, ENV['SCHEMA'])
     end
 
@@ -249,17 +249,17 @@ db_namespace = namespace :db do
     end
 
     namespace :cache do
-      desc 'Create a db/schema_cache.dump file.'
+      desc 'Creates a db/schema_cache.dump file.'
       task :dump => [:environment, :load_config] do
         con = ActiveRecord::Base.connection
         filename = File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, "schema_cache.dump")
 
         con.schema_cache.clear!
-        con.tables.each { |table| con.schema_cache.add(table) }
+        con.data_sources.each { |table| con.schema_cache.add(table) }
         open(filename, 'wb') { |f| f.write(Marshal.dump(con.schema_cache)) }
       end
 
-      desc 'Clear a db/schema_cache.dump file.'
+      desc 'Clears a db/schema_cache.dump file.'
       task :clear => [:environment, :load_config] do
         filename = File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, "schema_cache.dump")
         FileUtils.rm(filename) if File.exist?(filename)
@@ -269,9 +269,9 @@ db_namespace = namespace :db do
   end
 
   namespace :structure do
-    desc 'Dump the database structure to db/structure.sql. Specify another file with DB_STRUCTURE=db/my_structure.sql'
+    desc 'Dumps the database structure to db/structure.sql. Specify another file with SCHEMA=db/my_structure.sql'
     task :dump => [:environment, :load_config] do
-      filename = ENV['DB_STRUCTURE'] || File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, "structure.sql")
+      filename = ENV['SCHEMA'] || File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, "structure.sql")
       current_config = ActiveRecord::Tasks::DatabaseTasks.current_config
       ActiveRecord::Tasks::DatabaseTasks.structure_dump(current_config, filename)
 
@@ -285,9 +285,9 @@ db_namespace = namespace :db do
       db_namespace['structure:dump'].reenable
     end
 
-    desc "Recreate the databases from the structure.sql file"
-    task :load => [:environment, :load_config] do
-      ActiveRecord::Tasks::DatabaseTasks.load_schema_current(:sql, ENV['DB_STRUCTURE'])
+    desc "Recreates the databases from the structure.sql file"
+    task :load => [:load_config] do
+      ActiveRecord::Tasks::DatabaseTasks.load_schema_current(:sql, ENV['SCHEMA'])
     end
 
     task :load_if_sql => ['db:create', :environment] do
@@ -353,7 +353,7 @@ db_namespace = namespace :db do
       ActiveRecord::Tasks::DatabaseTasks.purge ActiveRecord::Base.configurations['test']
     end
 
-    # desc 'Check for pending migrations and load the test schema'
+    # desc 'Load the test schema'
     task :prepare => %w(environment load_config) do
       unless ActiveRecord::Base.configurations.blank?
         db_namespace['test:load'].invoke
@@ -384,7 +384,7 @@ namespace :railties do
         puts "Copied migration #{migration.basename} from #{name}"
       end
 
-      ActiveRecord::Migration.copy(ActiveRecord::Migrator.migrations_paths.first, railties,
+      ActiveRecord::Migration.copy(ActiveRecord::Tasks::DatabaseTasks.migrations_paths.first, railties,
                                     :on_skip => on_skip, :on_copy => on_copy)
     end
   end
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index dab5a502a5..5b9d45d871 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -32,6 +32,7 @@ module ActiveRecord
     end
 
     def self.add_reflection(ar, name, reflection)
+      ar.clear_reflections_cache
       ar._reflections = ar._reflections.merge(name.to_s => reflection)
     end
 
@@ -61,22 +62,27 @@ module ActiveRecord
         aggregate_reflections[aggregation.to_s]
       end
 
-      # Returns a Hash of name of the reflection as the key and a AssociationReflection as the value.
+      # Returns a Hash of name of the reflection as the key and an AssociationReflection as the value.
       #
       #   Account.reflections # => {"balance" => AggregateReflection}
       #
-      # @api public
       def reflections
-        ref = {}
-        _reflections.each do |name, reflection|
-          parent_name, parent_reflection = reflection.parent_reflection
-          if parent_name
-            ref[parent_name] = parent_reflection
-          else
-            ref[name] = reflection
+        @__reflections ||= begin
+          ref = {}
+
+          _reflections.each do |name, reflection|
+            parent_reflection = reflection.parent_reflection
+
+            if parent_reflection
+              parent_name = parent_reflection.name
+              ref[parent_name.to_s] = parent_reflection
+            else
+              ref[name] = reflection
+            end
           end
+
+          ref
         end
-        ref
       end
 
       # Returns an array of AssociationReflection objects for all the
@@ -89,10 +95,10 @@ module ActiveRecord
       #   Account.reflect_on_all_associations             # returns an array of all associations
       #   Account.reflect_on_all_associations(:has_many)  # returns an array of all has_many associations
       #
-      #   @api public
       def reflect_on_all_associations(macro = nil)
         association_reflections = reflections.values
-        macro ? association_reflections.select { |reflection| reflection.macro == macro } : association_reflections
+        association_reflections.select! { |reflection| reflection.macro == macro } if macro
+        association_reflections
       end
 
       # Returns the AssociationReflection object for the +association+ (use the symbol).
@@ -100,22 +106,22 @@ module ActiveRecord
       #   Account.reflect_on_association(:owner)             # returns the owner AssociationReflection
       #   Invoice.reflect_on_association(:line_items).macro  # returns :has_many
       #
-      #   @api public
       def reflect_on_association(association)
         reflections[association.to_s]
       end
 
-      #   @api private
       def _reflect_on_association(association) #:nodoc:
         _reflections[association.to_s]
       end
 
       # Returns an array of AssociationReflection objects for all associations which have <tt>:autosave</tt> enabled.
-      #
-      #   @api public
       def reflect_on_all_autosave_associations
         reflections.values.select { |reflection| reflection.options[:autosave] }
       end
+
+      def clear_reflections_cache # :nodoc:
+        @__reflections = nil
+      end
     end
 
     # Holds all the methods that are shared between MacroReflection, AssociationReflection
@@ -157,6 +163,68 @@ module ActiveRecord
         scope_chain.flatten
       end
 
+      def counter_cache_column
+        if belongs_to?
+          if options[:counter_cache] == true
+            "#{active_record.name.demodulize.underscore.pluralize}_count"
+          elsif options[:counter_cache]
+            options[:counter_cache].to_s
+          end
+        else
+          options[:counter_cache] ? options[:counter_cache].to_s : "#{name}_count"
+        end
+      end
+
+      def inverse_of
+        return unless inverse_name
+
+        @inverse_of ||= klass._reflect_on_association inverse_name
+      end
+
+      def check_validity_of_inverse!
+        unless polymorphic?
+          if has_inverse? && inverse_of.nil?
+            raise InverseOfAssociationNotFoundError.new(self)
+          end
+        end
+      end
+
+      # This shit is nasty. We need to avoid the following situation:
+      #
+      #   * An associated record is deleted via record.destroy
+      #   * Hence the callbacks run, and they find a belongs_to on the record with a
+      #     :counter_cache options which points back at our owner. So they update the
+      #     counter cache.
+      #   * In which case, we must make sure to *not* update the counter cache, or else
+      #     it will be decremented twice.
+      #
+      # Hence this method.
+      def inverse_which_updates_counter_cache
+        return @inverse_which_updates_counter_cache if defined?(@inverse_which_updates_counter_cache)
+        @inverse_which_updates_counter_cache = klass.reflect_on_all_associations(:belongs_to).find do |inverse|
+          inverse.counter_cache_column == counter_cache_column
+        end
+      end
+      alias inverse_updates_counter_cache? inverse_which_updates_counter_cache
+
+      def inverse_updates_counter_in_memory?
+        inverse_of && inverse_which_updates_counter_cache == inverse_of
+      end
+
+      # Returns whether a counter cache should be used for this association.
+      #
+      # The counter_cache option must be given on either the owner or inverse
+      # association, and the column must be present on the owner.
+      def has_cached_counter?
+        options[:counter_cache] ||
+          inverse_which_updates_counter_cache && inverse_which_updates_counter_cache.options[:counter_cache] &&
+          !!active_record.columns_hash[counter_cache_column]
+      end
+
+      def counter_must_be_updated_by_has_many?
+        !inverse_updates_counter_in_memory? && has_cached_counter?
+      end
+
       def alias_candidate(name)
         "#{plural_name}_#{name}"
       end
@@ -166,8 +234,8 @@ module ActiveRecord
     # AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
     #
     #   MacroReflection
+    #     AggregateReflection
     #     AssociationReflection
-    #       AggregateReflection
     #       HasManyReflection
     #       HasOneReflection
     #       BelongsToReflection
@@ -196,7 +264,7 @@ module ActiveRecord
         @scope         = scope
         @options       = options
         @active_record = active_record
-        @klass         = options[:class]
+        @klass         = options[:anonymous_class]
         @plural_name   = active_record.pluralize_table_names ?
                             name.to_s.pluralize : name.to_s
       end
@@ -204,7 +272,7 @@ module ActiveRecord
       def autosave=(autosave)
         @automatic_inverse_of = false
         @options[:autosave] = autosave
-        _, parent_reflection = self.parent_reflection
+        parent_reflection = self.parent_reflection
         if parent_reflection
           parent_reflection.autosave = autosave
         end
@@ -272,7 +340,7 @@ module ActiveRecord
       end
 
       attr_reader :type, :foreign_type
-      attr_accessor :parent_reflection # [:name, Reflection]
+      attr_accessor :parent_reflection # Reflection
 
       def initialize(name, scope, options, active_record)
         super
@@ -319,26 +387,10 @@ module ActiveRecord
         @active_record_primary_key ||= options[:primary_key] || primary_key(active_record)
       end
 
-      def counter_cache_column
-        if options[:counter_cache] == true
-          "#{active_record.name.demodulize.underscore.pluralize}_count"
-        elsif options[:counter_cache]
-          options[:counter_cache].to_s
-        end
-      end
-
       def check_validity!
         check_validity_of_inverse!
       end
 
-      def check_validity_of_inverse!
-        unless polymorphic?
-          if has_inverse? && inverse_of.nil?
-            raise InverseOfAssociationNotFoundError.new(self)
-          end
-        end
-      end
-
       def check_preloadable!
         return unless scope
 
@@ -370,6 +422,12 @@ module ActiveRecord
         [self]
       end
 
+      # This is for clearing cache on the reflection. Useful for tests that need to compare
+      # SQL queries on associations.
+      def clear_association_scope_cache # :nodoc:
+        @association_scope_cache.clear
+      end
+
       def nested?
         false
       end
@@ -384,12 +442,6 @@ module ActiveRecord
         inverse_name
       end
 
-      def inverse_of
-        return unless inverse_name
-
-        @inverse_of ||= klass._reflect_on_association inverse_name
-      end
-
       def polymorphic_inverse_of(associated_class)
         if has_inverse?
           if inverse_relationship = associated_class._reflect_on_association(options[:inverse_of])
@@ -629,7 +681,7 @@ module ActiveRecord
 
       def initialize(delegate_reflection)
         @delegate_reflection = delegate_reflection
-        @klass         = delegate_reflection.options[:class]
+        @klass         = delegate_reflection.options[:anonymous_class]
         @source_reflection_name = delegate_reflection.options[:source]
       end
 
@@ -694,7 +746,7 @@ module ActiveRecord
       def chain
         @chain ||= begin
           a = source_reflection.chain
-          b = through_reflection.chain
+          b = through_reflection.chain.map(&:dup)
 
           if options[:source_type]
             b[0] = PolymorphicReflection.new(b[0], self)
@@ -706,6 +758,15 @@ module ActiveRecord
         end
       end
 
+      # This is for clearing cache on the reflection. Useful for tests that need to compare
+      # SQL queries on associations.
+      def clear_association_scope_cache # :nodoc:
+        @chain = nil
+        delegate_reflection.clear_association_scope_cache
+        source_reflection.clear_association_scope_cache
+        through_reflection.clear_association_scope_cache
+      end
+
       # Consider the following example:
       #
       #   class Person
@@ -863,6 +924,8 @@ module ActiveRecord
           klass.primary_key || raise(UnknownPrimaryKey.new(klass))
         end
 
+        def inverse_name; delegate_reflection.send(:inverse_name); end
+
       private
         def derive_class_name
           # get the class_name of the belongs_to association of the through reflection
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index dd78814c6a..392b462aa9 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -1,19 +1,20 @@
-# -*- coding: utf-8 -*-
-require 'arel/collectors/bind'
+require "arel/collectors/bind"
 
 module ActiveRecord
-  # = Active Record Relation
+  # = Active Record \Relation
   class Relation
     MULTI_VALUE_METHODS  = [:includes, :eager_load, :preload, :select, :group,
-                            :order, :joins, :where, :having, :bind, :references,
+                            :order, :joins, :references,
                             :extending, :unscope]
 
-    SINGLE_VALUE_METHODS = [:limit, :offset, :lock, :readonly, :from, :reordering,
-                            :reverse_order, :distinct, :create_with, :uniq]
+    SINGLE_VALUE_METHODS = [:limit, :offset, :lock, :readonly, :reordering,
+                            :reverse_order, :distinct, :create_with]
+    CLAUSE_METHODS = [:where, :having, :from]
     INVALID_METHODS_FOR_DELETE_ALL = [:limit, :distinct, :offset, :group, :having]
 
-    VALUE_METHODS = MULTI_VALUE_METHODS + SINGLE_VALUE_METHODS
+    VALUE_METHODS = MULTI_VALUE_METHODS + SINGLE_VALUE_METHODS + CLAUSE_METHODS
 
+    include Enumerable
     include FinderMethods, Calculations, SpawnMethods, QueryMethods, Batches, Explain, Delegation
 
     attr_reader :table, :klass, :loaded, :predicate_builder
@@ -33,7 +34,6 @@ module ActiveRecord
       # This method is a hot spot, so for now, use Hash[] to dup the hash.
       #   https://bugs.ruby-lang.org/issues/7166
       @values        = Hash[@values]
-      @values[:bind] = @values[:bind].dup if @values.key? :bind
       reset
     end
 
@@ -81,7 +81,7 @@ module ActiveRecord
       end
 
       relation = scope.where(@klass.primary_key => (id_was || id))
-      bvs = binds + relation.bind_values
+      bvs = binds + relation.bound_attributes
       um = relation
         .arel
         .compile_update(substitutes, @klass.primary_key)
@@ -95,11 +95,11 @@ module ActiveRecord
 
     def substitute_values(values) # :nodoc:
       binds = values.map do |arel_attr, value|
-        [@klass.columns_hash[arel_attr.name], value]
+        QueryAttribute.new(arel_attr.name, value, klass.type_for_attribute(arel_attr.name))
       end
 
-      substitutes = values.each_with_index.map do |(arel_attr, _), i|
-        [arel_attr, @klass.connection.substitute_at(binds[i][0])]
+      substitutes = values.map do |(arel_attr, _)|
+        [arel_attr, connection.substitute_at(klass.columns_hash[arel_attr.name])]
       end
 
       [substitutes, binds]
@@ -108,7 +108,7 @@ module ActiveRecord
     # Initializes new record from relation while maintaining the current
     # scope.
     #
-    # Expects arguments in the same format as +Base.new+.
+    # Expects arguments in the same format as {ActiveRecord::Base.new}[rdoc-ref:Core.new].
     #
     #   users = User.where(name: 'DHH')
     #   user = users.new # => #<User id: nil, name: "DHH", created_at: nil, updated_at: nil>
@@ -126,28 +126,32 @@ module ActiveRecord
     # Tries to create a new record with the same scoped attributes
     # defined in the relation. Returns the initialized object if validation fails.
     #
-    # Expects arguments in the same format as +Base.create+.
+    # Expects arguments in the same format as
+    # {ActiveRecord::Base.create}[rdoc-ref:Persistence::ClassMethods#create].
     #
     # ==== Examples
+    #
     #   users = User.where(name: 'Oscar')
-    #   users.create # #<User id: 3, name: "oscar", ...>
+    #   users.create # => #<User id: 3, name: "oscar", ...>
     #
     #   users.create(name: 'fxn')
-    #   users.create # #<User id: 4, name: "fxn", ...>
+    #   users.create # => #<User id: 4, name: "fxn", ...>
     #
     #   users.create { |user| user.name = 'tenderlove' }
-    #   # #<User id: 5, name: "tenderlove", ...>
+    #   # => #<User id: 5, name: "tenderlove", ...>
     #
     #   users.create(name: nil) # validation on name
-    #   # #<User id: nil, name: nil, ...>
+    #   # => #<User id: nil, name: nil, ...>
     def create(*args, &block)
       scoping { @klass.create(*args, &block) }
     end
 
-    # Similar to #create, but calls +create!+ on the base class. Raises
-    # an exception if a validation error occurs.
+    # Similar to #create, but calls
+    # {create!}[rdoc-ref:Persistence::ClassMethods#create!]
+    # on the base class. Raises an exception if a validation error occurs.
     #
-    # Expects arguments in the same format as <tt>Base.create!</tt>.
+    # Expects arguments in the same format as
+    # {ActiveRecord::Base.create!}[rdoc-ref:Persistence::ClassMethods#create!].
     def create!(*args, &block)
       scoping { @klass.create!(*args, &block) }
     end
@@ -181,7 +185,7 @@ module ActiveRecord
     #   User.create_with(last_name: 'Johansson').find_or_create_by(first_name: 'Scarlett')
     #   # => #<User id: 2, first_name: "Scarlett", last_name: "Johansson">
     #
-    # This method accepts a block, which is passed down to +create+. The last example
+    # This method accepts a block, which is passed down to #create. The last example
     # above can be alternatively written this way:
     #
     #   # Find the first user named "Scarlett" or create a new one with a
@@ -193,7 +197,7 @@ module ActiveRecord
     #
     # This method always returns a record, but if creation was attempted and
     # failed due to validation errors it won't be persisted, you get what
-    # +create+ returns in such situation.
+    # #create returns in such situation.
     #
     # Please note *this method is not atomic*, it runs first a SELECT, and if
     # there are no results an INSERT is attempted. If there are other threads
@@ -205,7 +209,9 @@ module ActiveRecord
     # constraint an exception may be raised, just retry:
     #
     #  begin
-    #    CreditAccount.find_or_create_by(user_id: user.id)
+    #    CreditAccount.transaction(requires_new: true) do
+    #      CreditAccount.find_or_create_by(user_id: user.id)
+    #    end
     #  rescue ActiveRecord::RecordNotUnique
     #    retry
     #  end
@@ -214,13 +220,15 @@ module ActiveRecord
       find_by(attributes) || create(attributes, &block)
     end
 
-    # Like <tt>find_or_create_by</tt>, but calls <tt>create!</tt> so an exception
+    # Like #find_or_create_by, but calls
+    # {create!}[rdoc-ref:Persistence::ClassMethods#create!] so an exception
     # is raised if the created record is invalid.
     def find_or_create_by!(attributes, &block)
       find_by(attributes) || create!(attributes, &block)
     end
 
-    # Like <tt>find_or_create_by</tt>, but calls <tt>new</tt> instead of <tt>create</tt>.
+    # Like #find_or_create_by, but calls {new}[rdoc-ref:Core#new]
+    # instead of {create}[rdoc-ref:Persistence::ClassMethods#create].
     def find_or_initialize_by(attributes, &block)
       find_by(attributes) || new(attributes, &block)
     end
@@ -271,22 +279,54 @@ module ActiveRecord
       end
     end
 
+    # Returns true if there are no records.
+    def none?
+      return super if block_given?
+      empty?
+    end
+
     # Returns true if there are any records.
     def any?
-      if block_given?
-        to_a.any? { |*block_args| yield(*block_args) }
-      else
-        !empty?
-      end
+      return super if block_given?
+      !empty?
+    end
+
+    # Returns true if there is exactly one record.
+    def one?
+      return super if block_given?
+      limit_value ? to_a.one? : size == 1
     end
 
     # Returns true if there is more than one record.
     def many?
-      if block_given?
-        to_a.many? { |*block_args| yield(*block_args) }
-      else
-        limit_value ? to_a.many? : size > 1
-      end
+      return super if block_given?
+      limit_value ? to_a.many? : size > 1
+    end
+
+    # Returns a cache key that can be used to identify the records fetched by
+    # this query. The cache key is built with a fingerprint of the sql query,
+    # the number of records matched by the query and a timestamp of the last
+    # updated record. When a new record comes to match the query, or any of
+    # the existing records is updated or deleted, the cache key changes.
+    #
+    #   Product.where("name like ?", "%Cosmic Encounter%").cache_key
+    #   # => "products/query-1850ab3d302391b85b8693e941286659-1-20150714212553907087000"
+    #
+    # If the collection is loaded, the method will iterate through the records
+    # to generate the timestamp, otherwise it will trigger one SQL query like:
+    #
+    #    SELECT COUNT(*), MAX("products"."updated_at") FROM "products" WHERE (name like '%Cosmic Encounter%')
+    #
+    # You can also pass a custom timestamp column to fetch the timestamp of the
+    # last updated record.
+    #
+    #   Product.where("name like ?", "%Game%").cache_key(:last_reviewed_at)
+    #
+    # You can customize the strategy to generate the key on a per model basis
+    # overriding ActiveRecord::Base#collection_cache_key.
+    def cache_key(timestamp_column = :updated_at)
+      @cache_keys ||= {}
+      @cache_keys[timestamp_column] ||= @klass.collection_cache_key(self, timestamp_column)
     end
 
     # Scope all queries to the current scope.
@@ -307,8 +347,8 @@ module ActiveRecord
 
     # Updates all records in the current relation with details given. This method constructs a single SQL UPDATE
     # statement and sends it straight to the database. It does not instantiate the involved models and it does not
-    # trigger Active Record callbacks or validations. Values passed to `update_all` will not go through
-    # ActiveRecord's type-casting behavior. It should receive only values that can be passed as-is to the SQL
+    # trigger Active Record callbacks or validations. Values passed to #update_all will not go through
+    # Active Record's type-casting behavior. It should receive only values that can be passed as-is to the SQL
     # database.
     #
     # ==== Parameters
@@ -342,8 +382,7 @@ module ActiveRecord
         stmt.wheres = arel.constraints
       end
 
-      bvs = arel.bind_values + bind_values
-      @klass.connection.update stmt, 'SQL', bvs
+      @klass.connection.update stmt, 'SQL', bound_attributes
     end
 
     # Updates an object (or multiple objects) and saves it to the database, if validations pass.
@@ -367,27 +406,34 @@ module ActiveRecord
     #   people = Person.where(group: 'expert')
     #   people.update(group: 'masters')
     #
-    #   Note: Updating a large number of records will run a
-    #   UPDATE query for each record, which may cause a performance
-    #   issue. So if it is not needed to run callbacks for each update, it is
-    #   preferred to use <tt>update_all</tt> for updating all records using
-    #   a single query.
+    # Note: Updating a large number of records will run an
+    # UPDATE query for each record, which may cause a performance
+    # issue. So if it is not needed to run callbacks for each update, it is
+    # preferred to use #update_all for updating all records using
+    # a single query.
     def update(id = :all, attributes)
       if id.is_a?(Array)
         id.map.with_index { |one_id, idx| update(one_id, attributes[idx]) }
       elsif id == :all
         to_a.each { |record| record.update(attributes) }
       else
+        if ActiveRecord::Base === id
+          id = id.id
+          ActiveSupport::Deprecation.warn(<<-MSG.squish)
+            You are passing an instance of ActiveRecord::Base to `update`.
+            Please pass the id of the object by calling `.id`
+          MSG
+        end
         object = find(id)
         object.update(attributes)
         object
       end
     end
 
-    # Destroys the records matching +conditions+ by instantiating each
-    # record and calling its +destroy+ method. Each object's callbacks are
-    # executed (including <tt>:dependent</tt> association options). Returns the
-    # collection of objects that were destroyed; each will be frozen, to
+    # Destroys the records by instantiating each
+    # record and calling its {#destroy}[rdoc-ref:Persistence#destroy] method.
+    # Each object's callbacks are executed (including <tt>:dependent</tt> association options).
+    # Returns the collection of objects that were destroyed; each will be frozen, to
     # reflect that no changes should be made (since they can't be persisted).
     #
     # Note: Instantiation, callback execution, and deletion of each
@@ -395,22 +441,17 @@ module ActiveRecord
     # once. It generates at least one SQL +DELETE+ query per record (or
     # possibly more, to enforce your callbacks). If you want to delete many
     # rows quickly, without concern for their associations or callbacks, use
-    # +delete_all+ instead.
-    #
-    # ==== Parameters
-    #
-    # * +conditions+ - A string, array, or hash that specifies which records
-    #   to destroy. If omitted, all records are destroyed. See the
-    #   Conditions section in the introduction to ActiveRecord::Base for
-    #   more information.
+    # #delete_all instead.
     #
     # ==== Examples
     #
-    #   Person.destroy_all("last_login < '2004-04-04'")
-    #   Person.destroy_all(status: "inactive")
     #   Person.where(age: 0..18).destroy_all
     def destroy_all(conditions = nil)
       if conditions
+        ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+          Passing conditions to destroy_all is deprecated and will be removed in Rails 5.1.
+          To achieve the same use where(conditions).destroy_all
+        MESSAGE
         where(conditions).destroy_all
       else
         to_a.each(&:destroy).tap { reset }
@@ -419,7 +460,7 @@ module ActiveRecord
 
     # Destroy an object (or multiple objects) that has the given id. The object is instantiated first,
     # therefore all callbacks and filters are fired off before the object is deleted. This method is
-    # less efficient than ActiveRecord#delete but allows cleanup methods and other actions to be run.
+    # less efficient than #delete but allows cleanup methods and other actions to be run.
     #
     # This essentially finds the object (or multiple objects) with the given id, creates a new object
     # from the attributes, and then calls destroy on it.
@@ -444,22 +485,21 @@ module ActiveRecord
       end
     end
 
-    # Deletes the records matching +conditions+ without instantiating the records
-    # first, and hence not calling the +destroy+ method nor invoking callbacks. This
-    # is a single SQL DELETE statement that goes straight to the database, much more
-    # efficient than +destroy_all+. Be careful with relations though, in particular
+    # Deletes the records without instantiating the records
+    # first, and hence not calling the {#destroy}[rdoc-ref:Persistence#destroy]
+    # method nor invoking callbacks.
+    # This is a single SQL DELETE statement that goes straight to the database, much more
+    # efficient than #destroy_all. Be careful with relations though, in particular
     # <tt>:dependent</tt> rules defined on associations are not honored. Returns the
     # number of rows affected.
     #
-    #   Post.delete_all("person_id = 5 AND (category = 'Something' OR category = 'Else')")
-    #   Post.delete_all(["person_id = ? AND (category = ? OR category = ?)", 5, 'Something', 'Else'])
     #   Post.where(person_id: 5).where(category: ['Something', 'Else']).delete_all
     #
     # Both calls delete the affected posts all at once with a single DELETE statement.
     # If you need to destroy dependent associations or call your <tt>before_*</tt> or
-    # +after_destroy+ callbacks, use the +destroy_all+ method instead.
+    # +after_destroy+ callbacks, use the #destroy_all method instead.
     #
-    # If an invalid method is supplied, +delete_all+ raises an ActiveRecord error:
+    # If an invalid method is supplied, #delete_all raises an ActiveRecordError:
     #
     #   Post.limit(100).delete_all
     #   # => ActiveRecord::ActiveRecordError: delete_all doesn't support limit
@@ -467,8 +507,10 @@ module ActiveRecord
       invalid_methods = INVALID_METHODS_FOR_DELETE_ALL.select { |method|
         if MULTI_VALUE_METHODS.include?(method)
           send("#{method}_values").any?
-        else
+        elsif SINGLE_VALUE_METHODS.include?(method)
           send("#{method}_value")
+        elsif CLAUSE_METHODS.include?(method)
+          send("#{method}_clause").any?
         end
       }
       if invalid_methods.any?
@@ -476,6 +518,10 @@ module ActiveRecord
       end
 
       if conditions
+        ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+          Passing conditions to delete_all is deprecated and will be removed in Rails 5.1.
+          To achieve the same use where(conditions).delete_all
+        MESSAGE
         where(conditions).delete_all
       else
         stmt = Arel::DeleteManager.new
@@ -487,7 +533,7 @@ module ActiveRecord
           stmt.wheres = arel.constraints
         end
 
-        affected = @klass.connection.delete(stmt, 'SQL', bind_values)
+        affected = @klass.connection.delete(stmt, 'SQL', bound_attributes)
 
         reset
         affected
@@ -502,7 +548,7 @@ module ActiveRecord
     # You can delete multiple rows at once by passing an Array of <tt>id</tt>s.
     #
     # Note: Although it is often much faster than the alternative,
-    # <tt>#destroy</tt>, skipping callbacks might bypass business logic in
+    # #destroy, skipping callbacks might bypass business logic in
     # your application that ensures referential integrity or performs other
     # essential jobs.
     #
@@ -557,11 +603,10 @@ module ActiveRecord
                       find_with_associations { |rel| relation = rel }
                     end
 
-                    arel  = relation.arel
-                    binds = arel.bind_values + relation.bind_values
+                    binds = relation.bound_attributes
                     binds = connection.prepare_binds_for_database(binds)
-                    binds.map! { |_, value| connection.quote(value) }
-                    collect = visitor.accept(arel.ast, Arel::Collectors::Bind.new)
+                    binds.map! { |value| connection.quote(value) }
+                    collect = visitor.accept(relation.arel.ast, Arel::Collectors::Bind.new)
                     collect.substitute_binds(binds).join
                   end
     end
@@ -571,22 +616,7 @@ module ActiveRecord
     #   User.where(name: 'Oscar').where_values_hash
     #   # => {name: "Oscar"}
     def where_values_hash(relation_table_name = table_name)
-      equalities = where_values.grep(Arel::Nodes::Equality).find_all { |node|
-        node.left.relation.name == relation_table_name
-      }
-
-      binds = Hash[bind_values.find_all(&:first).map { |column, v| [column.name, v] }]
-
-      Hash[equalities.map { |where|
-        name = where.left.name
-        [name, binds.fetch(name.to_s) {
-          case where.right
-          when Array then where.right.map(&:val)
-          when Arel::Nodes::Casted, Arel::Nodes::Quoted
-            where.right.val
-          end
-        }]
-      }]
+      where_clause.to_h(relation_table_name)
     end
 
     def scope_for_create
@@ -608,11 +638,14 @@ module ActiveRecord
       includes_values & joins_values
     end
 
-    # +uniq+ and +uniq!+ are silently deprecated. +uniq_value+ delegates to +distinct_value+
-    # to maintain backwards compatibility. Use +distinct_value+ instead.
+    # {#uniq}[rdoc-ref:QueryMethods#uniq] and
+    # {#uniq!}[rdoc-ref:QueryMethods#uniq!] are silently deprecated.
+    # #uniq_value delegates to #distinct_value to maintain backwards compatibility.
+    # Use #distinct_value instead.
     def uniq_value
       distinct_value
     end
+    deprecate uniq_value: :distinct_value
 
     # Compares two relations for equality.
     def ==(other)
@@ -646,10 +679,17 @@ module ActiveRecord
       "#<#{self.class.name} [#{entries.join(', ')}]>"
     end
 
+    protected
+
+      def load_records(records)
+        @records = records
+        @loaded = true
+      end
+
     private
 
     def exec_queries
-      @records = eager_loading? ? find_with_associations : @klass.find_by_sql(arel, arel.bind_values + bind_values)
+      @records = eager_loading? ? find_with_associations : @klass.find_by_sql(arel, bound_attributes)
 
       preload = preload_values
       preload +=  includes_values unless eager_loading?
diff --git a/activerecord/lib/active_record/relation/batches.rb b/activerecord/lib/active_record/relation/batches.rb
index 4f0502ae75..221bc73680 100644
--- a/activerecord/lib/active_record/relation/batches.rb
+++ b/activerecord/lib/active_record/relation/batches.rb
@@ -1,8 +1,10 @@
+require "active_record/relation/batches/batch_enumerator"
+
 module ActiveRecord
   module Batches
     # Looping through a collection of records from the database
-    # (using the +all+ method, for example) is very inefficient
-    # since it will try to instantiate all the objects at once.
+    # (using the Scoping::Named::ClassMethods.all method, for example)
+    # is very inefficient since it will try to instantiate all the objects at once.
     #
     # In that case, batch processing methods allow you to work
     # with the records in batches, thereby greatly reducing memory consumption.
@@ -27,14 +29,15 @@ module ActiveRecord
     #
     # ==== Options
     # * <tt>:batch_size</tt> - Specifies the size of the batch. Default to 1000.
-    # * <tt>:start</tt> - Specifies the primary key value to start from.
+    # * <tt>:begin_at</tt> - Specifies the primary key value to start from, inclusive of the value.
+    # * <tt>:end_at</tt> - Specifies the primary key value to end at, inclusive of the value.
     # This is especially useful if you want multiple workers dealing with
     # the same processing queue. You can make worker 1 handle all the records
     # between id 0 and 10,000 and worker 2 handle from 10,000 and beyond
-    # (by setting the +:start+ option on that worker).
+    # (by setting the +:begin_at+ and +:end_at+ option on each worker).
     #
     #   # Let's process for a batch of 2000 records, skipping the first 2000 rows
-    #   Person.find_each(start: 2000, batch_size: 2000) do |person|
+    #   Person.find_each(begin_at: 2000, batch_size: 2000) do |person|
     #     person.party_all_night!
     #   end
     #
@@ -45,19 +48,27 @@ module ActiveRecord
     #
     # NOTE: You can't set the limit either, that's used to control
     # the batch sizes.
-    def find_each(options = {})
+    def find_each(begin_at: nil, end_at: nil, batch_size: 1000, start: nil)
+      if start
+        begin_at = start
+        ActiveSupport::Deprecation.warn(<<-MSG.squish)
+            Passing `start` value to find_each is deprecated, and will be removed in Rails 5.1.
+            Please pass `begin_at` instead.
+        MSG
+      end
       if block_given?
-        find_in_batches(options) do |records|
+        find_in_batches(begin_at: begin_at, end_at: end_at, batch_size: batch_size) do |records|
           records.each { |record| yield record }
         end
       else
-        enum_for :find_each, options do
-          options[:start] ? where(table[primary_key].gteq(options[:start])).size : size
+        enum_for(:find_each, begin_at: begin_at, end_at: end_at, batch_size: batch_size) do
+          relation = self
+          apply_limits(relation, begin_at, end_at).size
         end
       end
     end
 
-    # Yields each batch of records that was found by the find +options+ as
+    # Yields each batch of records that was found by the find options as
     # an array.
     #
     #   Person.where("age > 21").find_in_batches do |group|
@@ -77,14 +88,15 @@ module ActiveRecord
     #
     # ==== Options
     # * <tt>:batch_size</tt> - Specifies the size of the batch. Default to 1000.
-    # * <tt>:start</tt> - Specifies the primary key value to start from.
+    # * <tt>:begin_at</tt> - Specifies the primary key value to start from, inclusive of the value.
+    # * <tt>:end_at</tt> - Specifies the primary key value to end at, inclusive of the value.
     # This is especially useful if you want multiple workers dealing with
     # the same processing queue. You can make worker 1 handle all the records
     # between id 0 and 10,000 and worker 2 handle from 10,000 and beyond
-    # (by setting the +:start+ option on that worker).
+    # (by setting the +:begin_at+ and +:end_at+ option on each worker).
     #
     #   # Let's process the next 2000 records
-    #   Person.find_in_batches(start: 2000, batch_size: 2000) do |group|
+    #   Person.find_in_batches(begin_at: 2000, batch_size: 2000) do |group|
     #     group.each { |person| person.party_all_night! }
     #   end
     #
@@ -95,42 +107,130 @@ module ActiveRecord
     #
     # NOTE: You can't set the limit either, that's used to control
     # the batch sizes.
-    def find_in_batches(options = {})
-      options.assert_valid_keys(:start, :batch_size)
+    def find_in_batches(begin_at: nil, end_at: nil, batch_size: 1000, start: nil)
+      if start
+        begin_at = start
+        ActiveSupport::Deprecation.warn(<<-MSG.squish)
+            Passing `start` value to find_in_batches is deprecated, and will be removed in Rails 5.1.
+            Please pass `begin_at` instead.
+        MSG
+      end
 
       relation = self
-      start = options[:start]
-      batch_size = options[:batch_size] || 1000
-
       unless block_given?
-        return to_enum(:find_in_batches, options) do
-          total = start ? where(table[primary_key].gteq(start)).size : size
+        return to_enum(:find_in_batches, begin_at: begin_at, end_at: end_at, batch_size: batch_size) do
+          total = apply_limits(relation, begin_at, end_at).size
           (total - 1).div(batch_size) + 1
         end
       end
 
+      in_batches(of: batch_size, begin_at: begin_at, end_at: end_at, load: true) do |batch|
+        yield batch.to_a
+      end
+    end
+
+    # Yields ActiveRecord::Relation objects to work with a batch of records.
+    #
+    #   Person.where("age > 21").in_batches do |relation|
+    #     relation.delete_all
+    #     sleep(10) # Throttle the delete queries
+    #   end
+    #
+    # If you do not provide a block to #in_batches, it will return a
+    # BatchEnumerator which is enumerable.
+    #
+    #   Person.in_batches.with_index do |relation, batch_index|
+    #     puts "Processing relation ##{batch_index}"
+    #     relation.each { |relation| relation.delete_all }
+    #   end
+    #
+    # Examples of calling methods on the returned BatchEnumerator object:
+    #
+    #   Person.in_batches.delete_all
+    #   Person.in_batches.update_all(awesome: true)
+    #   Person.in_batches.each_record(&:party_all_night!)
+    #
+    # ==== Options
+    # * <tt>:of</tt> - Specifies the size of the batch. Default to 1000.
+    # * <tt>:load</tt> - Specifies if the relation should be loaded. Default to false.
+    # * <tt>:begin_at</tt> - Specifies the primary key value to start from, inclusive of the value.
+    # * <tt>:end_at</tt> - Specifies the primary key value to end at, inclusive of the value.
+    #
+    # This is especially useful if you want to work with the
+    # ActiveRecord::Relation object instead of the array of records, or if
+    # you want multiple workers dealing with the same processing queue. You can
+    # make worker 1 handle all the records between id 0 and 10,000 and worker 2
+    # handle from 10,000 and beyond (by setting the +:begin_at+ and +:end_at+
+    # option on each worker).
+    #
+    #   # Let's process the next 2000 records
+    #   Person.in_batches(of: 2000, begin_at: 2000).update_all(awesome: true)
+    #
+    # An example of calling where query method on the relation:
+    #
+    #   Person.in_batches.each do |relation|
+    #     relation.update_all('age = age + 1')
+    #     relation.where('age > 21').update_all(should_party: true)
+    #     relation.where('age <= 21').delete_all
+    #   end
+    #
+    # NOTE: If you are going to iterate through each record, you should call
+    # #each_record on the yielded BatchEnumerator:
+    #
+    #   Person.in_batches.each_record(&:party_all_night!)
+    #
+    # NOTE: It's not possible to set the order. That is automatically set to
+    # ascending on the primary key ("id ASC") to make the batch ordering
+    # consistent. Therefore the primary key must be orderable, e.g an integer
+    # or a string.
+    #
+    # NOTE: You can't set the limit either, that's used to control the batch
+    # sizes.
+    def in_batches(of: 1000, begin_at: nil, end_at: nil, load: false)
+      relation = self
+      unless block_given?
+        return BatchEnumerator.new(of: of, begin_at: begin_at, end_at: end_at, relation: self)
+      end
+
       if logger && (arel.orders.present? || arel.taken.present?)
         logger.warn("Scoped order and limit are ignored, it's forced to be batch order and batch size")
       end
 
-      relation = relation.reorder(batch_order).limit(batch_size)
-      records = start ? relation.where(table[primary_key].gteq(start)).to_a : relation.to_a
+      relation = relation.reorder(batch_order).limit(of)
+      relation = apply_limits(relation, begin_at, end_at)
+      batch_relation = relation
 
-      while records.any?
-        records_size = records.size
-        primary_key_offset = records.last.id
-        raise "Primary key not included in the custom select clause" unless primary_key_offset
+      loop do
+        if load
+          records = batch_relation.to_a
+          ids = records.map(&:id)
+          yielded_relation = self.where(primary_key => ids)
+          yielded_relation.load_records(records)
+        else
+          ids = batch_relation.pluck(primary_key)
+          yielded_relation = self.where(primary_key => ids)
+        end
+
+        break if ids.empty?
 
-        yield records
+        primary_key_offset = ids.last
+        raise ArgumentError.new("Primary key not included in the custom select clause") unless primary_key_offset
 
-        break if records_size < batch_size
+        yield yielded_relation
 
-        records = relation.where(table[primary_key].gt(primary_key_offset)).to_a
+        break if ids.length < of
+        batch_relation = relation.where(table[primary_key].gt(primary_key_offset))
       end
     end
 
     private
 
+    def apply_limits(relation, begin_at, end_at)
+      relation = relation.where(table[primary_key].gteq(begin_at)) if begin_at
+      relation = relation.where(table[primary_key].lteq(end_at)) if end_at
+      relation
+    end
+
     def batch_order
       "#{quoted_table_name}.#{quoted_primary_key} ASC"
     end
diff --git a/activerecord/lib/active_record/relation/batches/batch_enumerator.rb b/activerecord/lib/active_record/relation/batches/batch_enumerator.rb
new file mode 100644
index 0000000000..153aae9584
--- /dev/null
+++ b/activerecord/lib/active_record/relation/batches/batch_enumerator.rb
@@ -0,0 +1,67 @@
+module ActiveRecord
+  module Batches
+    class BatchEnumerator
+      include Enumerable
+
+      def initialize(of: 1000, begin_at: nil, end_at: nil, relation:) #:nodoc:
+        @of       = of
+        @relation = relation
+        @begin_at = begin_at
+        @end_at   = end_at
+      end
+
+      # Looping through a collection of records from the database (using the
+      # +all+ method, for example) is very inefficient since it will try to
+      # instantiate all the objects at once.
+      #
+      # In that case, batch processing methods allow you to work with the
+      # records in batches, thereby greatly reducing memory consumption.
+      #
+      #   Person.in_batches.each_record do |person|
+      #     person.do_awesome_stuff
+      #   end
+      #
+      #   Person.where("age > 21").in_batches(of: 10).each_record do |person|
+      #     person.party_all_night!
+      #   end
+      #
+      # If you do not provide a block to #each_record, it will return an Enumerator
+      # for chaining with other methods:
+      #
+      #   Person.in_batches.each_record.with_index do |person, index|
+      #     person.award_trophy(index + 1)
+      #   end
+      def each_record
+        return to_enum(:each_record) unless block_given?
+
+        @relation.to_enum(:in_batches, of: @of, begin_at: @begin_at, end_at: @end_at, load: true).each do |relation|
+          relation.to_a.each { |record| yield record }
+        end
+      end
+
+      # Delegates #delete_all, #update_all, #destroy_all methods to each batch.
+      #
+      #   People.in_batches.delete_all
+      #   People.in_batches.destroy_all('age < 10')
+      #   People.in_batches.update_all('age = age + 1')
+      [:delete_all, :update_all, :destroy_all].each do |method|
+        define_method(method) do |*args, &block|
+          @relation.to_enum(:in_batches, of: @of, begin_at: @begin_at, end_at: @end_at, load: false).each do |relation|
+            relation.send(method, *args, &block)
+          end
+        end
+      end
+
+      # Yields an ActiveRecord::Relation object for each batch of records.
+      #
+      #   Person.in_batches.each do |relation|
+      #     relation.update_all(awesome: true)
+      #   end
+      def each
+        enum = @relation.to_enum(:in_batches, of: @of, begin_at: @begin_at, end_at: @end_at, load: false)
+        return enum.each { |relation| yield relation } if block_given?
+        enum
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 1d4cb1a83b..f45844a9ea 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -14,33 +14,34 @@ module ActiveRecord
     #   Person.distinct.count(:age)
     #   # => counts the number of different age values
     #
-    # If +count+ is used with +group+, it returns a Hash whose keys represent the aggregated column,
+    # If #count is used with {Relation#group}[rdoc-ref:QueryMethods#group],
+    # it returns a Hash whose keys represent the aggregated column,
     # and the values are the respective amounts:
     #
     #   Person.group(:city).count
     #   # => { 'Rome' => 5, 'Paris' => 3 }
     #
-    # If +count+ is used with +group+ for multiple columns, it returns a Hash whose
+    # If #count is used with {Relation#group}[rdoc-ref:QueryMethods#group] for multiple columns, it returns a Hash whose
     # keys are an array containing the individual values of each column and the value
-    # of each key would be the +count+.
+    # of each key would be the #count.
     #
     #   Article.group(:status, :category).count
     #   # =>  {["draft", "business"]=>10, ["draft", "technology"]=>4,
     #          ["published", "business"]=>0, ["published", "technology"]=>2}
     #
-    # If +count+ is used with +select+, it will count the selected columns:
+    # If #count is used with {Relation#select}[rdoc-ref:QueryMethods#select], it will count the selected columns:
     #
     #   Person.select(:age).count
     #   # => counts the number of different age values
     #
-    # Note: not all valid +select+ expressions are valid +count+ expressions. The specifics differ
+    # Note: not all valid {Relation#select}[rdoc-ref:QueryMethods#select] expressions are valid #count expressions. The specifics differ
     # between databases. In invalid cases, an error from the database is thrown.
     def count(column_name = nil)
       calculate(:count, column_name)
     end
 
     # Calculates the average value on a given column. Returns +nil+ if there's
-    # no row. See +calculate+ for examples with options.
+    # no row. See #calculate for examples with options.
     #
     #   Person.average(:age) # => 35.8
     def average(column_name)
@@ -49,7 +50,7 @@ module ActiveRecord
 
     # Calculates the minimum value on a given column. The value is returned
     # with the same data type of the column, or +nil+ if there's no row. See
-    # +calculate+ for examples with options.
+    # #calculate for examples with options.
     #
     #   Person.minimum(:age) # => 7
     def minimum(column_name)
@@ -58,7 +59,7 @@ module ActiveRecord
 
     # Calculates the maximum value on a given column. The value is returned
     # with the same data type of the column, or +nil+ if there's no row. See
-    # +calculate+ for examples with options.
+    # #calculate for examples with options.
     #
     #   Person.maximum(:age) # => 93
     def maximum(column_name)
@@ -66,45 +67,46 @@ module ActiveRecord
     end
 
     # Calculates the sum of values on a given column. The value is returned
-    # with the same data type of the column, 0 if there's no row. See
-    # +calculate+ for examples with options.
+    # with the same data type of the column, +0+ if there's no row. See
+    # #calculate for examples with options.
     #
     #   Person.sum(:age) # => 4562
-    def sum(*args)
-      calculate(:sum, *args)
+    def sum(column_name = nil, &block)
+      return super(&block) if block_given?
+      calculate(:sum, column_name)
     end
 
-    # This calculates aggregate values in the given column. Methods for count, sum, average,
-    # minimum, and maximum have been added as shortcuts.
+    # This calculates aggregate values in the given column. Methods for #count, #sum, #average,
+    # #minimum, and #maximum have been added as shortcuts.
     #
-    # There are two basic forms of output:
+    #   Person.calculate(:count, :all) # The same as Person.count
+    #   Person.average(:age) # SELECT AVG(age) FROM people...
     #
-    #   * Single aggregate value: The single value is type cast to Fixnum for COUNT, Float
-    #     for AVG, and the given column's type for everything else.
+    #   # Selects the minimum age for any family without any minors
+    #   Person.group(:last_name).having("min(age) > 17").minimum(:age)
     #
-    #   * Grouped values: This returns an ordered hash of the values and groups them. It
-    #     takes either a column name, or the name of a belongs_to association.
+    #   Person.sum("2 * age")
     #
-    #       values = Person.group('last_name').maximum(:age)
-    #       puts values["Drake"]
-    #       # => 43
+    # There are two basic forms of output:
     #
-    #       drake  = Family.find_by(last_name: 'Drake')
-    #       values = Person.group(:family).maximum(:age) # Person belongs_to :family
-    #       puts values[drake]
-    #       # => 43
+    # * Single aggregate value: The single value is type cast to Fixnum for COUNT, Float
+    #   for AVG, and the given column's type for everything else.
     #
-    #       values.each do |family, max_age|
-    #       ...
-    #       end
+    # * Grouped values: This returns an ordered hash of the values and groups them. It
+    #   takes either a column name, or the name of a belongs_to association.
     #
-    #   Person.calculate(:count, :all) # The same as Person.count
-    #   Person.average(:age) # SELECT AVG(age) FROM people...
+    #      values = Person.group('last_name').maximum(:age)
+    #      puts values["Drake"]
+    #      # => 43
     #
-    #   # Selects the minimum age for any family without any minors
-    #   Person.group(:last_name).having("min(age) > 17").minimum(:age)
+    #      drake  = Family.find_by(last_name: 'Drake')
+    #      values = Person.group(:family).maximum(:age) # Person belongs_to :family
+    #      puts values[drake]
+    #      # => 43
     #
-    #   Person.sum("2 * age")
+    #      values.each do |family, max_age|
+    #        ...
+    #      end
     def calculate(operation, column_name)
       if column_name.is_a?(Symbol) && attribute_alias?(column_name)
         column_name = attribute_alias(column_name)
@@ -117,7 +119,7 @@ module ActiveRecord
       end
     end
 
-    # Use <tt>pluck</tt> as a shortcut to select one or more attributes without
+    # Use #pluck as a shortcut to select one or more attributes without
     # loading a bunch of records just to grab the attributes you want.
     #
     #   Person.pluck(:name)
@@ -126,19 +128,19 @@ module ActiveRecord
     #
     #   Person.all.map(&:name)
     #
-    # Pluck returns an <tt>Array</tt> of attribute values type-casted to match
+    # Pluck returns an Array of attribute values type-casted to match
     # the plucked column names, if they can be deduced. Plucking an SQL fragment
     # returns String values by default.
     #
-    #   Person.pluck(:id)
-    #   # SELECT people.id FROM people
-    #   # => [1, 2, 3]
+    #   Person.pluck(:name)
+    #   # SELECT people.name FROM people
+    #   # => ['David', 'Jeremy', 'Jose']
     #
     #   Person.pluck(:id, :name)
     #   # SELECT people.id, people.name FROM people
     #   # => [[1, 'David'], [2, 'Jeremy'], [3, 'Jose']]
     #
-    #   Person.pluck('DISTINCT role')
+    #   Person.distinct.pluck(:role)
     #   # SELECT DISTINCT role FROM people
     #   # => ['admin', 'member', 'guest']
     #
@@ -150,6 +152,8 @@ module ActiveRecord
     #   # SELECT DATEDIFF(updated_at, created_at) FROM people
     #   # => ['0', '27761', '173']
     #
+    # See also #ids.
+    #
     def pluck(*column_names)
       column_names.map! do |column_name|
         if column_name.is_a?(Symbol) && attribute_alias?(column_name)
@@ -159,6 +163,10 @@ module ActiveRecord
         end
       end
 
+      if loaded? && (column_names - @klass.column_names).empty?
+        return @records.pluck(*column_names)
+      end
+
       if has_include?(column_names.first)
         construct_relation_for_association_calculations.pluck(*column_names)
       else
@@ -166,8 +174,8 @@ module ActiveRecord
         relation.select_values = column_names.map { |cn|
           columns_hash.key?(cn) ? arel_table[cn] : cn
         }
-        result = klass.connection.select_all(relation.arel, nil, relation.arel.bind_values + bind_values)
-        result.cast_values(klass.column_types)
+        result = klass.connection.select_all(relation.arel, nil, bound_attributes)
+        result.cast_values(klass.attribute_types)
       end
     end
 
@@ -182,13 +190,14 @@ module ActiveRecord
     private
 
     def has_include?(column_name)
-      eager_loading? || (includes_values.present? && ((column_name && column_name != :all) || references_eager_loaded_tables?))
+      eager_loading? || (includes_values.present? && column_name && column_name != :all)
     end
 
     def perform_calculation(operation, column_name)
       operation = operation.to_s.downcase
 
-      # If #count is used with #distinct / #uniq it is considered distinct. (eg. relation.distinct.count)
+      # If #count is used with #distinct (i.e. `relation.distinct.count`) it is
+      # considered distinct.
       distinct = self.distinct_value
 
       if operation == "count"
@@ -210,6 +219,8 @@ module ActiveRecord
     end
 
     def aggregate_column(column_name)
+      return column_name if Arel::Expressions === column_name
+
       if @klass.column_names.include?(column_name.to_s)
         Arel::Attribute.new(@klass.unscoped.table, column_name)
       else
@@ -222,19 +233,16 @@ module ActiveRecord
     end
 
     def execute_simple_calculation(operation, column_name, distinct) #:nodoc:
-      # Postgresql doesn't like ORDER BY when there are no GROUP BY
+      # PostgreSQL doesn't like ORDER BY when there are no GROUP BY
       relation = unscope(:order)
 
       column_alias = column_name
 
-      bind_values = nil
-
       if operation == "count" && (relation.limit_value || relation.offset_value)
         # Shortcut when limit is zero.
         return 0 if relation.limit_value == 0
 
         query_builder = build_count_subquery(relation, column_name, distinct)
-        bind_values = query_builder.bind_values + relation.bind_values
       else
         column = aggregate_column(column_name)
 
@@ -245,10 +253,9 @@ module ActiveRecord
         relation.select_values = [select_value]
 
         query_builder = relation.arel
-        bind_values = query_builder.bind_values + relation.bind_values
       end
 
-      result = @klass.connection.select_all(query_builder, nil, bind_values)
+      result = @klass.connection.select_all(query_builder, nil, bound_attributes)
       row    = result.first
       value  = row && row.values.first
       column = result.column_types.fetch(column_alias) do
@@ -268,15 +275,10 @@ module ActiveRecord
       else
         group_fields = group_attrs
       end
+      group_fields = arel_columns(group_fields)
 
-      group_aliases = group_fields.map { |field|
-        column_alias_for(field)
-      }
-      group_columns = group_aliases.zip(group_fields).map { |aliaz,field|
-        [aliaz, field]
-      }
-
-      group = group_fields
+      group_aliases = group_fields.map { |field| column_alias_for(field) }
+      group_columns = group_aliases.zip(group_fields)
 
       if operation == 'count' && column_name == :all
         aggregate_alias = 'count_all'
@@ -290,9 +292,9 @@ module ActiveRecord
           operation,
           distinct).as(aggregate_alias)
       ]
-      select_values += select_values unless having_values.empty?
+      select_values += select_values unless having_clause.empty?
 
-      select_values.concat group_fields.zip(group_aliases).map { |field,aliaz|
+      select_values.concat group_columns.map { |aliaz, field|
         if field.respond_to?(:as)
           field.as(aliaz)
         else
@@ -301,14 +303,14 @@ module ActiveRecord
       }
 
       relation = except(:group)
-      relation.group_values  = group
+      relation.group_values  = group_fields
       relation.select_values = select_values
 
-      calculated_data = @klass.connection.select_all(relation, nil, relation.arel.bind_values + bind_values)
+      calculated_data = @klass.connection.select_all(relation, nil, relation.bound_attributes)
 
       if association
         key_ids     = calculated_data.collect { |row| row[group_aliases.first] }
-        key_records = association.klass.base_class.find(key_ids)
+        key_records = association.klass.base_class.where(association.klass.base_class.primary_key => key_ids)
         key_records = Hash[key_records.map { |r| [r.id, r] }]
       end
 
@@ -334,7 +336,6 @@ module ActiveRecord
     #   column_alias_for("sum(id)")                  # => "sum_id"
     #   column_alias_for("count(distinct users.id)") # => "count_distinct_users_id"
     #   column_alias_for("count(*)")                 # => "count_all"
-    #   column_alias_for("count", "id")              # => "count_id"
     def column_alias_for(keys)
       if keys.respond_to? :name
         keys = "#{keys.relation.name}.#{keys.name}"
@@ -357,15 +358,15 @@ module ActiveRecord
     def type_cast_calculated_value(value, type, operation = nil)
       case operation
         when 'count'   then value.to_i
-        when 'sum'     then type.type_cast_from_database(value || 0)
+        when 'sum'     then type.deserialize(value || 0)
         when 'average' then value.respond_to?(:to_d) ? value.to_d : value
-        else type.type_cast_from_database(value)
+        else type.deserialize(value)
       end
     end
 
-    # TODO: refactor to allow non-string `select_values` (eg. Arel nodes).
     def select_for_count
       if select_values.present?
+        return select_values.first if select_values.one?
         select_values.join(", ")
       else
         :all
@@ -378,11 +379,9 @@ module ActiveRecord
 
       aliased_column = aggregate_column(column_name == :all ? 1 : column_name).as(column_alias)
       relation.select_values = [aliased_column]
-      arel = relation.arel
-      subquery = arel.as(subquery_alias)
+      subquery = relation.arel.as(subquery_alias)
 
       sm = Arel::SelectManager.new relation.engine
-      sm.bind_values = arel.bind_values
       select_value = operation_over_aggregate_column(column_alias, 'count', distinct)
       sm.project(select_value).from(subquery)
     end
diff --git a/activerecord/lib/active_record/relation/delegation.rb b/activerecord/lib/active_record/relation/delegation.rb
index d4a8823cfe..27de313d05 100644
--- a/activerecord/lib/active_record/relation/delegation.rb
+++ b/activerecord/lib/active_record/relation/delegation.rb
@@ -3,12 +3,12 @@ require 'active_support/concern'
 
 module ActiveRecord
   module Delegation # :nodoc:
-    module DelegateCache
-      def relation_delegate_class(klass) # :nodoc:
+    module DelegateCache # :nodoc:
+      def relation_delegate_class(klass)
         @relation_delegate_cache[klass]
       end
 
-      def initialize_relation_delegate_cache # :nodoc:
+      def initialize_relation_delegate_cache
         @relation_delegate_cache = cache = {}
         [
           ActiveRecord::Relation,
@@ -18,7 +18,7 @@ module ActiveRecord
           delegate = Class.new(klass) {
             include ClassSpecificRelation
           }
-          const_set klass.name.gsub('::', '_'), delegate
+          const_set klass.name.gsub('::'.freeze, '_'.freeze), delegate
           cache[klass] = delegate
         end
       end
@@ -39,7 +39,7 @@ module ActiveRecord
     BLACKLISTED_ARRAY_METHODS = [
       :compact!, :flatten!, :reject!, :reverse!, :rotate!, :map!,
       :shuffle!, :slice!, :sort!, :sort_by!, :delete_if,
-      :keep_if, :pop, :shift, :delete_at, :compact, :select!
+      :keep_if, :pop, :shift, :delete_at, :select!
     ].to_set # :nodoc:
 
     delegate :to_xml, :to_yaml, :length, :collect, :map, :each, :all?, :include?, :to_ary, :join, to: :to_a
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 088bc203b7..435cef901b 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -1,4 +1,3 @@
-require 'active_support/deprecation'
 require 'active_support/core_ext/string/filters'
 
 module ActiveRecord
@@ -6,7 +5,7 @@ module ActiveRecord
     ONE_AS_ONE = '1 AS one'
 
     # Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]).
-    # If no record can be found for all of the listed ids, then RecordNotFound will be raised. If the primary key
+    # If one or more records can not be found for the requested ids, then RecordNotFound will be raised. If the primary key
     # is an integer, find by id coerces its arguments using +to_i+.
     #
     #   Person.find(1)          # returns the object for ID = 1
@@ -17,10 +16,8 @@ module ActiveRecord
     #   Person.find([1])        # returns an array for the object with ID = 1
     #   Person.where("administrator = 1").order("created_on DESC").find(1)
     #
-    # <tt>ActiveRecord::RecordNotFound</tt> will be raised if one or more ids are not found.
-    #
     # NOTE: The returned records may not be in the same order as the ids you
-    # provide since database rows are unordered. You'd need to provide an explicit <tt>order</tt>
+    # provide since database rows are unordered. You'd need to provide an explicit QueryMethods#order
     # option if you want the results are sorted.
     #
     # ==== Find with lock
@@ -37,7 +34,7 @@ module ActiveRecord
     #     person.save!
     #   end
     #
-    # ==== Variations of +find+
+    # ==== Variations of #find
     #
     #   Person.where(name: 'Spartacus', rating: 4)
     #   # returns a chainable list (which can be empty).
@@ -49,9 +46,9 @@ module ActiveRecord
     #   # returns the first item or returns a new instance (requires you call .save to persist against the database).
     #
     #   Person.where(name: 'Spartacus', rating: 4).first_or_create
-    #   # returns the first item or creates it and returns it, available since Rails 3.2.1.
+    #   # returns the first item or creates it and returns it.
     #
-    # ==== Alternatives for +find+
+    # ==== Alternatives for #find
     #
     #   Person.where(name: 'Spartacus', rating: 4).exists?(conditions = :none)
     #   # returns a boolean indicating if any record with the given conditions exist.
@@ -60,16 +57,13 @@ module ActiveRecord
     #   # returns a chainable list of instances with only the mentioned fields.
     #
     #   Person.where(name: 'Spartacus', rating: 4).ids
-    #   # returns an Array of ids, available since Rails 3.2.1.
+    #   # returns an Array of ids.
     #
     #   Person.where(name: 'Spartacus', rating: 4).pluck(:field1, :field2)
-    #   # returns an Array of the required fields, available since Rails 3.1.
+    #   # returns an Array of the required fields.
     def find(*args)
-      if block_given?
-        to_a.find(*args) { |*block_args| yield(*block_args) }
-      else
-        find_with_ids(*args)
-      end
+      return super if block_given?
+      find_with_ids(*args)
     end
 
     # Finds the first record matching the specified conditions. There
@@ -80,18 +74,19 @@ module ActiveRecord
     #
     #   Post.find_by name: 'Spartacus', rating: 4
     #   Post.find_by "published_at < ?", 2.weeks.ago
-    def find_by(*args)
-      where(*args).take
+    def find_by(arg, *args)
+      where(arg, *args).take
     rescue RangeError
       nil
     end
 
-    # Like <tt>find_by</tt>, except that if no record is found, raises
-    # an <tt>ActiveRecord::RecordNotFound</tt> error.
-    def find_by!(*args)
-      where(*args).take!
+    # Like #find_by, except that if no record is found, raises
+    # an ActiveRecord::RecordNotFound error.
+    def find_by!(arg, *args)
+      where(arg, *args).take!
     rescue RangeError
-      raise RecordNotFound, "Couldn't find #{@klass.name} with an out of range value"
+      raise RecordNotFound.new("Couldn't find #{@klass.name} with an out of range value",
+                               @klass.name)
     end
 
     # Gives a record (or N records if a parameter is supplied) without any implied
@@ -105,8 +100,8 @@ module ActiveRecord
       limit ? limit(limit).to_a : find_take
     end
 
-    # Same as +take+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
-    # is found. Note that <tt>take!</tt> accepts no arguments.
+    # Same as #take but raises ActiveRecord::RecordNotFound if no record
+    # is found. Note that #take! accepts no arguments.
     def take!
       take or raise RecordNotFound.new("Couldn't find #{@klass.name} with [#{arel.where_sql(@klass.arel_engine)}]")
     end
@@ -114,23 +109,11 @@ module ActiveRecord
     # Find the first record (or first N records if a parameter is supplied).
     # If no order is defined it will order by primary key.
     #
-    #   Person.first # returns the first object fetched by SELECT * FROM people
+    #   Person.first # returns the first object fetched by SELECT * FROM people ORDER BY people.id LIMIT 1
     #   Person.where(["user_name = ?", user_name]).first
     #   Person.where(["user_name = :u", { u: user_name }]).first
     #   Person.order("created_on DESC").offset(5).first
-    #   Person.first(3) # returns the first three objects fetched by SELECT * FROM people LIMIT 3
-    #
-    # ==== Rails 3
-    #
-    #   Person.first # SELECT "people".* FROM "people" LIMIT 1
-    #
-    # NOTE: Rails 3 may not order this query by the primary key and the order
-    # will depend on the database implementation. In order to ensure that behavior,
-    # use <tt>User.order(:id).first</tt> instead.
-    #
-    # ==== Rails 4
-    #
-    #   Person.first # SELECT "people".* FROM "people" ORDER BY "people"."id" ASC LIMIT 1
+    #   Person.first(3) # returns the first three objects fetched by SELECT * FROM people ORDER BY people.id LIMIT 3
     #
     def first(limit = nil)
       if limit
@@ -140,8 +123,8 @@ module ActiveRecord
       end
     end
 
-    # Same as +first+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
-    # is found. Note that <tt>first!</tt> accepts no arguments.
+    # Same as #first but raises ActiveRecord::RecordNotFound if no record
+    # is found. Note that #first! accepts no arguments.
     def first!
       find_nth! 0
     end
@@ -173,8 +156,8 @@ module ActiveRecord
       end
     end
 
-    # Same as +last+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
-    # is found. Note that <tt>last!</tt> accepts no arguments.
+    # Same as #last but raises ActiveRecord::RecordNotFound if no record
+    # is found. Note that #last! accepts no arguments.
     def last!
       last or raise RecordNotFound.new("Couldn't find #{@klass.name} with [#{arel.where_sql(@klass.arel_engine)}]")
     end
@@ -189,7 +172,7 @@ module ActiveRecord
       find_nth(1, offset_index)
     end
 
-    # Same as +second+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
+    # Same as #second but raises ActiveRecord::RecordNotFound if no record
     # is found.
     def second!
       find_nth! 1
@@ -205,7 +188,7 @@ module ActiveRecord
       find_nth(2, offset_index)
     end
 
-    # Same as +third+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
+    # Same as #third but raises ActiveRecord::RecordNotFound if no record
     # is found.
     def third!
       find_nth! 2
@@ -221,7 +204,7 @@ module ActiveRecord
       find_nth(3, offset_index)
     end
 
-    # Same as +fourth+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
+    # Same as #fourth but raises ActiveRecord::RecordNotFound if no record
     # is found.
     def fourth!
       find_nth! 3
@@ -237,7 +220,7 @@ module ActiveRecord
       find_nth(4, offset_index)
     end
 
-    # Same as +fifth+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
+    # Same as #fifth but raises ActiveRecord::RecordNotFound if no record
     # is found.
     def fifth!
       find_nth! 4
@@ -253,14 +236,14 @@ module ActiveRecord
       find_nth(41, offset_index)
     end
 
-    # Same as +forty_two+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
+    # Same as #forty_two but raises ActiveRecord::RecordNotFound if no record
     # is found.
     def forty_two!
       find_nth! 41
     end
 
-    # Returns +true+ if a record exists in the table that matches the +id+ or
-    # conditions given, or +false+ otherwise. The argument can take six forms:
+    # Returns true if a record exists in the table that matches the +id+ or
+    # conditions given, or false otherwise. The argument can take six forms:
     #
     # * Integer - Finds the record with this primary key.
     # * String - Finds the record with a primary key corresponding to this
@@ -273,7 +256,7 @@ module ActiveRecord
     # * No args - Returns +false+ if the table is empty, +true+ otherwise.
     #
     # For more information about specifying conditions as a hash or array,
-    # see the Conditions section in the introduction to <tt>ActiveRecord::Base</tt>.
+    # see the Conditions section in the introduction to ActiveRecord::Base.
     #
     # Note: You can't pass in a condition as a string (like <tt>name =
     # 'Jamie'</tt>), since it would be sanitized and then queried against
@@ -307,15 +290,15 @@ module ActiveRecord
         relation = relation.where(conditions)
       else
         unless conditions == :none
-          relation = where(primary_key => conditions)
+          relation = relation.where(primary_key => conditions)
         end
       end
 
-      connection.select_value(relation, "#{name} Exists", relation.arel.bind_values + relation.bind_values) ? true : false
+      connection.select_value(relation, "#{name} Exists", relation.bound_attributes) ? true : false
     end
 
     # This method is called whenever no records are found with either a single
-    # id or multiple ids and raises a +ActiveRecord::RecordNotFound+ exception.
+    # id or multiple ids and raises a ActiveRecord::RecordNotFound exception.
     #
     # The error message is different depending on whether a single id or
     # multiple ids are provided. If multiple ids are provided, then the number
@@ -365,7 +348,7 @@ module ActiveRecord
           []
         else
           arel = relation.arel
-          rows = connection.select_all(arel, 'SQL', arel.bind_values + relation.bind_values)
+          rows = connection.select_all(arel, 'SQL', relation.bound_attributes)
           join_dependency.instantiate(rows, aliases)
         end
       end
@@ -379,7 +362,7 @@ module ActiveRecord
     def construct_relation_for_association_calculations
       from = arel.froms.first
       if Arel::Table === from
-        apply_join_dependency(self, construct_join_dependency)
+        apply_join_dependency(self, construct_join_dependency(joins_values))
       else
         # FIXME: as far as I can tell, `from` will always be an Arel::Table.
         # There are no tests that test this branch, but presumably it's
@@ -410,7 +393,7 @@ module ActiveRecord
       relation = relation.except(:select).select(values).distinct!
       arel = relation.arel
 
-      id_rows = @klass.connection.select_all(arel, 'SQL', arel.bind_values + relation.bind_values)
+      id_rows = @klass.connection.select_all(arel, 'SQL', relation.bound_attributes)
       id_rows.map {|row| row[primary_key]}
     end
 
diff --git a/activerecord/lib/active_record/relation/from_clause.rb b/activerecord/lib/active_record/relation/from_clause.rb
new file mode 100644
index 0000000000..92340216ed
--- /dev/null
+++ b/activerecord/lib/active_record/relation/from_clause.rb
@@ -0,0 +1,32 @@
+module ActiveRecord
+  class Relation
+    class FromClause # :nodoc:
+      attr_reader :value, :name
+
+      def initialize(value, name)
+        @value = value
+        @name = name
+      end
+
+      def binds
+        if value.is_a?(Relation)
+          value.bound_attributes
+        else
+          []
+        end
+      end
+
+      def merge(other)
+        self
+      end
+
+      def empty?
+        value.nil?
+      end
+
+      def self.empty
+        new(nil, nil)
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/relation/merger.rb b/activerecord/lib/active_record/relation/merger.rb
index afb0b208c3..cb971eb255 100644
--- a/activerecord/lib/active_record/relation/merger.rb
+++ b/activerecord/lib/active_record/relation/merger.rb
@@ -1,5 +1,4 @@
 require 'active_support/core_ext/hash/keys'
-require "set"
 
 module ActiveRecord
   class Relation
@@ -49,9 +48,9 @@ module ActiveRecord
         @other    = other
       end
 
-      NORMAL_VALUES = Relation::SINGLE_VALUE_METHODS +
-                      Relation::MULTI_VALUE_METHODS -
-                      [:joins, :where, :order, :bind, :reverse_order, :lock, :create_with, :reordering, :from] # :nodoc:
+      NORMAL_VALUES = Relation::VALUE_METHODS -
+                      Relation::CLAUSE_METHODS -
+                      [:includes, :preload, :joins, :order, :reverse_order, :lock, :create_with, :reordering] # :nodoc:
 
       def normal_values
         NORMAL_VALUES
@@ -75,6 +74,8 @@ module ActiveRecord
 
         merge_multi_values
         merge_single_values
+        merge_clauses
+        merge_preloads
         merge_joins
 
         relation
@@ -82,6 +83,27 @@ module ActiveRecord
 
       private
 
+      def merge_preloads
+        return if other.preload_values.empty? && other.includes_values.empty?
+
+        if other.klass == relation.klass
+          relation.preload!(*other.preload_values) unless other.preload_values.empty?
+          relation.includes!(other.includes_values) unless other.includes_values.empty?
+        else
+          reflection = relation.klass.reflect_on_all_associations.find do |r|
+            r.class_name == other.klass.name
+          end || return
+
+          unless other.preload_values.empty?
+            relation.preload! reflection.name => other.preload_values
+          end
+
+          unless other.includes_values.empty?
+            relation.includes! reflection.name => other.includes_values
+          end
+        end
+      end
+
       def merge_joins
         return if other.joins_values.blank?
 
@@ -107,20 +129,6 @@ module ActiveRecord
       end
 
       def merge_multi_values
-        lhs_wheres = relation.where_values
-        rhs_wheres = other.where_values
-
-        lhs_binds  = relation.bind_values
-        rhs_binds  = other.bind_values
-
-        removed, kept = partition_overwrites(lhs_wheres, rhs_wheres)
-
-        where_values = kept + rhs_wheres
-        bind_values  = filter_binds(lhs_binds, removed) + rhs_binds
-
-        relation.where_values = where_values
-        relation.bind_values  = bind_values
-
         if other.reordering_value
           # override any order specified in the original relation
           relation.reorder! other.order_values
@@ -133,36 +141,22 @@ module ActiveRecord
       end
 
       def merge_single_values
-        relation.from_value          = other.from_value unless relation.from_value
-        relation.lock_value          = other.lock_value unless relation.lock_value
+        relation.lock_value ||= other.lock_value
 
         unless other.create_with_value.blank?
           relation.create_with_value = (relation.create_with_value || {}).merge(other.create_with_value)
         end
       end
 
-      def filter_binds(lhs_binds, removed_wheres)
-        return lhs_binds if removed_wheres.empty?
-
-        set = Set.new removed_wheres.map { |x| x.left.name.to_s }
-        lhs_binds.dup.delete_if { |col,_| set.include? col.name }
+      CLAUSE_METHOD_NAMES = CLAUSE_METHODS.map do |name|
+        ["#{name}_clause", "#{name}_clause="]
       end
 
-      # Remove equalities from the existing relation with a LHS which is
-      # present in the relation being merged in.
-      # returns [things_to_remove, things_to_keep]
-      def partition_overwrites(lhs_wheres, rhs_wheres)
-        if lhs_wheres.empty? || rhs_wheres.empty?
-          return [[], lhs_wheres]
-        end
-
-        nodes = rhs_wheres.find_all do |w|
-          w.respond_to?(:operator) && w.operator == :==
-        end
-        seen = Set.new(nodes) { |node| node.left }
-
-        lhs_wheres.partition do |w|
-          w.respond_to?(:operator) && w.operator == :== && seen.include?(w.left)
+      def merge_clauses
+        CLAUSE_METHOD_NAMES.each do |(reader, writer)|
+          clause = relation.send(reader)
+          other_clause = other.send(reader)
+          relation.send(writer, clause.merge(other_clause))
         end
       end
     end
diff --git a/activerecord/lib/active_record/relation/predicate_builder.rb b/activerecord/lib/active_record/relation/predicate_builder.rb
index 567efce8ae..39e7b42629 100644
--- a/activerecord/lib/active_record/relation/predicate_builder.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder.rb
@@ -24,10 +24,15 @@ module ActiveRecord
     end
 
     def build_from_hash(attributes)
-      attributes = convert_dot_notation_to_hash(attributes.stringify_keys)
+      attributes = convert_dot_notation_to_hash(attributes)
       expand_from_hash(attributes)
     end
 
+    def create_binds(attributes)
+      attributes = convert_dot_notation_to_hash(attributes)
+      create_binds_for_hash(attributes)
+    end
+
     def expand(column, value)
       # Find the foreign key when using queries such as:
       # Post.where(author: author)
@@ -47,7 +52,7 @@ module ActiveRecord
           key
         else
           key = key.to_s
-          key.split('.').first if key.include?('.')
+          key.split('.'.freeze).first if key.include?('.'.freeze)
         end
       end.compact
     end
@@ -62,7 +67,7 @@ module ActiveRecord
     #         Arel::Nodes::And.new([range.start, range.end])
     #       )
     #     end
-    #     ActiveRecord::PredicateBuilder.register_handler(MyCustomDateRange, handler)
+    #     ActiveRecord::PredicateBuilder.new("users").register_handler(MyCustomDateRange, handler)
     def register_handler(klass, handler)
       @handlers.unshift([klass, handler])
     end
@@ -80,21 +85,48 @@ module ActiveRecord
 
       attributes.flat_map do |key, value|
         if value.is_a?(Hash)
-          builder = self.class.new(table.associated_table(key))
-          builder.expand_from_hash(value)
+          associated_predicate_builder(key).expand_from_hash(value)
         else
           expand(key, value)
         end
       end
     end
 
+
+    def create_binds_for_hash(attributes)
+      result = attributes.dup
+      binds = []
+
+      attributes.each do |column_name, value|
+        case value
+        when Hash
+          attrs, bvs = associated_predicate_builder(column_name).create_binds_for_hash(value)
+          result[column_name] = attrs
+          binds += bvs
+        when Relation
+          binds += value.bound_attributes
+        else
+          if can_be_bound?(column_name, value)
+            result[column_name] = Arel::Nodes::BindParam.new
+            binds << Relation::QueryAttribute.new(column_name.to_s, value, table.type(column_name))
+          end
+        end
+      end
+
+      [result, binds]
+    end
+
     private
 
+    def associated_predicate_builder(association_name)
+      self.class.new(table.associated_table(association_name))
+    end
+
     def convert_dot_notation_to_hash(attributes)
-      dot_notation = attributes.keys.select { |s| s.include?(".") }
+      dot_notation = attributes.keys.select { |s| s.include?(".".freeze) }
 
       dot_notation.each do |key|
-        table_name, column_name = key.split(".")
+        table_name, column_name = key.split(".".freeze)
         value = attributes.delete(key)
         attributes[table_name] ||= {}
 
@@ -107,5 +139,11 @@ module ActiveRecord
     def handler_for(object)
       @handlers.detect { |klass, _| klass === object }.last
     end
+
+    def can_be_bound?(column_name, value)
+      !value.nil? &&
+        handler_for(value).is_a?(BasicObjectHandler) &&
+        !table.associated_with?(column_name)
+    end
   end
 end
diff --git a/activerecord/lib/active_record/relation/predicate_builder/association_query_handler.rb b/activerecord/lib/active_record/relation/predicate_builder/association_query_handler.rb
index aabcf20c1d..e81be63cd3 100644
--- a/activerecord/lib/active_record/relation/predicate_builder/association_query_handler.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder/association_query_handler.rb
@@ -10,10 +10,10 @@ module ActiveRecord
 
         table = value.associated_table
         if value.base_class
-          queries[table.association_foreign_type] = value.base_class.name
+          queries[table.association_foreign_type.to_s] = value.base_class.name
         end
 
-        queries[table.association_foreign_key] = value.ids
+        queries[table.association_foreign_key.to_s] = value.ids
         predicate_builder.build_from_hash(queries)
       end
 
@@ -31,7 +31,14 @@ module ActiveRecord
       end
 
       def ids
-        value
+        case value
+        when Relation
+          value.select(primary_key)
+        when Array
+          value.map { |v| convert_to_id(v) }
+        else
+          convert_to_id(value)
+        end
       end
 
       def base_class
@@ -42,6 +49,10 @@ module ActiveRecord
 
       private
 
+      def primary_key
+        associated_table.association_primary_key(base_class)
+      end
+
       def polymorphic_base_class_from_value
         case value
         when Relation
@@ -53,6 +64,15 @@ module ActiveRecord
           value.class.base_class
         end
       end
+
+      def convert_to_id(value)
+        case value
+        when Base
+          value._read_attribute(primary_key)
+        else
+          value
+        end
+      end
     end
   end
 end
diff --git a/activerecord/lib/active_record/relation/query_attribute.rb b/activerecord/lib/active_record/relation/query_attribute.rb
new file mode 100644
index 0000000000..7ba964e802
--- /dev/null
+++ b/activerecord/lib/active_record/relation/query_attribute.rb
@@ -0,0 +1,19 @@
+require 'active_record/attribute'
+
+module ActiveRecord
+  class Relation
+    class QueryAttribute < Attribute # :nodoc:
+      def type_cast(value)
+        value
+      end
+
+      def value_for_database
+        @value_for_database ||= super
+      end
+
+      def with_cast_value(value)
+        QueryAttribute.new(name, value, type)
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index d6e6cb4d05..f5afc1000d 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -1,5 +1,7 @@
-require 'active_support/core_ext/array/wrap'
-require 'active_support/core_ext/string/filters'
+require "active_record/relation/from_clause"
+require "active_record/relation/query_attribute"
+require "active_record/relation/where_clause"
+require "active_record/relation/where_clause_factory"
 require 'active_model/forbidden_attributes_protection'
 
 module ActiveRecord
@@ -18,7 +20,7 @@ module ActiveRecord
       # Returns a new relation expressing WHERE + NOT condition according to
       # the conditions in the arguments.
       #
-      # +not+ accepts conditions as a string, array, or hash. See #where for
+      # #not accepts conditions as a string, array, or hash. See QueryMethods#where for
       # more details on each format.
       #
       #    User.where.not("name = 'Jon'")
@@ -39,23 +41,10 @@ module ActiveRecord
       #    User.where.not(name: "Jon", role: "admin")
       #    # SELECT * FROM users WHERE name != 'Jon' AND role != 'admin'
       def not(opts, *rest)
-        where_value = @scope.send(:build_where, opts, rest).map do |rel|
-          case rel
-          when NilClass
-            raise ArgumentError, 'Invalid argument for .where.not(), got nil.'
-          when Arel::Nodes::In
-            Arel::Nodes::NotIn.new(rel.left, rel.right)
-          when Arel::Nodes::Equality
-            Arel::Nodes::NotEqual.new(rel.left, rel.right)
-          when String
-            Arel::Nodes::Not.new(Arel::Nodes::SqlLiteral.new(rel))
-          else
-            Arel::Nodes::Not.new(rel)
-          end
-        end
+        where_clause = @scope.send(:where_clause_factory).build(opts, rest)
 
         @scope.references!(PredicateBuilder.references(opts)) if Hash === opts
-        @scope.where_values += where_value
+        @scope.where_clause += where_clause.invert
         @scope
       end
     end
@@ -90,6 +79,23 @@ module ActiveRecord
       CODE
     end
 
+    Relation::CLAUSE_METHODS.each do |name|
+      class_eval <<-CODE, __FILE__, __LINE__ + 1
+        def #{name}_clause                           # def where_clause
+          @values[:#{name}] || new_#{name}_clause    #   @values[:where] || new_where_clause
+        end                                          # end
+                                                     #
+        def #{name}_clause=(value)                   # def where_clause=(value)
+          assert_mutability!                         #   assert_mutability!
+          @values[:#{name}] = value                  #   @values[:where] = value
+        end                                          # end
+      CODE
+    end
+
+    def bound_attributes
+      from_clause.binds + arel.bind_values + where_clause.binds + having_clause.binds
+    end
+
     def create_with_value # :nodoc:
       @values[:create_with] || {}
     end
@@ -106,7 +112,7 @@ module ActiveRecord
     #
     # allows you to access the +address+ attribute of the +User+ model without
     # firing an additional query. This will often result in a
-    # performance improvement over a simple +join+.
+    # performance improvement over a simple join.
     #
     # You can also specify multiple relationships, like this:
     #
@@ -127,7 +133,7 @@ module ActiveRecord
     #
     #   User.includes(:posts).where('posts.name = ?', 'example').references(:posts)
     #
-    # Note that +includes+ works with association names while +references+ needs
+    # Note that #includes works with association names while #references needs
     # the actual table name.
     def includes(*args)
       check_if_method_has_arguments!(:includes, args)
@@ -145,9 +151,9 @@ module ActiveRecord
     # Forces eager loading by performing a LEFT OUTER JOIN on +args+:
     #
     #   User.eager_load(:posts)
-    #   => SELECT "users"."id" AS t0_r0, "users"."name" AS t0_r1, ...
-    #   FROM "users" LEFT OUTER JOIN "posts" ON "posts"."user_id" =
-    #   "users"."id"
+    #   # SELECT "users"."id" AS t0_r0, "users"."name" AS t0_r1, ...
+    #   # FROM "users" LEFT OUTER JOIN "posts" ON "posts"."user_id" =
+    #   # "users"."id"
     def eager_load(*args)
       check_if_method_has_arguments!(:eager_load, args)
       spawn.eager_load!(*args)
@@ -158,10 +164,10 @@ module ActiveRecord
       self
     end
 
-    # Allows preloading of +args+, in the same way that +includes+ does:
+    # Allows preloading of +args+, in the same way that #includes does:
     #
     #   User.preload(:posts)
-    #   => SELECT "posts".* FROM "posts" WHERE "posts"."user_id" IN (1, 2, 3)
+    #   # SELECT "posts".* FROM "posts" WHERE "posts"."user_id" IN (1, 2, 3)
     def preload(*args)
       check_if_method_has_arguments!(:preload, args)
       spawn.preload!(*args)
@@ -174,14 +180,14 @@ module ActiveRecord
 
     # Use to indicate that the given +table_names+ are referenced by an SQL string,
     # and should therefore be JOINed in any query rather than loaded separately.
-    # This method only works in conjunction with +includes+.
+    # This method only works in conjunction with #includes.
     # See #includes for more details.
     #
     #   User.includes(:posts).where("posts.name = 'foo'")
-    #   # => Doesn't JOIN the posts table, resulting in an error.
+    #   # Doesn't JOIN the posts table, resulting in an error.
     #
     #   User.includes(:posts).where("posts.name = 'foo'").references(:posts)
-    #   # => Query now knows the string references posts, so adds a JOIN
+    #   # Query now knows the string references posts, so adds a JOIN
     def references(*table_names)
       check_if_method_has_arguments!(:references, table_names)
       spawn.references!(*table_names)
@@ -197,12 +203,12 @@ module ActiveRecord
 
     # Works in two unique ways.
     #
-    # First: takes a block so it can be used just like Array#select.
+    # First: takes a block so it can be used just like +Array#select+.
     #
     #   Model.all.select { |m| m.field == value }
     #
     # This will build an array of objects from the database for the scope,
-    # converting them into an array and iterating through them using Array#select.
+    # converting them into an array and iterating through them using +Array#select+.
     #
     # Second: Modifies the SELECT statement for the query so that only certain
     # fields are retrieved:
@@ -230,23 +236,20 @@ module ActiveRecord
     #   # => "value"
     #
     # Accessing attributes of an object that do not have fields retrieved by a select
-    # except +id+ will throw <tt>ActiveModel::MissingAttributeError</tt>:
+    # except +id+ will throw ActiveModel::MissingAttributeError:
     #
     #   Model.select(:field).first.other_field
     #   # => ActiveModel::MissingAttributeError: missing attribute: other_field
     def select(*fields)
-      if block_given?
-        to_a.select { |*block_args| yield(*block_args) }
-      else
-        raise ArgumentError, 'Call this with at least one field' if fields.empty?
-        spawn._select!(*fields)
-      end
+      return super if block_given?
+      raise ArgumentError, 'Call this with at least one field' if fields.empty?
+      spawn._select!(*fields)
     end
 
     def _select!(*fields) # :nodoc:
       fields.flatten!
       fields.map! do |field|
-        klass.attribute_alias?(field) ? klass.attribute_alias(field) : field
+        klass.attribute_alias?(field) ? klass.attribute_alias(field).to_sym : field
       end
       self.select_values += fields
       self
@@ -255,22 +258,23 @@ module ActiveRecord
     # Allows to specify a group attribute:
     #
     #   User.group(:name)
-    #   => SELECT "users".* FROM "users" GROUP BY name
+    #   # SELECT "users".* FROM "users" GROUP BY name
     #
     # Returns an array with distinct records based on the +group+ attribute:
     #
     #   User.select([:id, :name])
-    #   => [#<User id: 1, name: "Oscar">, #<User id: 2, name: "Oscar">, #<User id: 3, name: "Foo">
+    #   # => [#<User id: 1, name: "Oscar">, #<User id: 2, name: "Oscar">, #<User id: 3, name: "Foo">]
     #
     #   User.group(:name)
-    #   => [#<User id: 3, name: "Foo", ...>, #<User id: 2, name: "Oscar", ...>]
+    #   # => [#<User id: 3, name: "Foo", ...>, #<User id: 2, name: "Oscar", ...>]
     #
     #   User.group('name AS grouped_name, age')
-    #   => [#<User id: 3, name: "Foo", age: 21, ...>, #<User id: 2, name: "Oscar", age: 21, ...>, #<User id: 5, name: "Foo", age: 23, ...>]
+    #   # => [#<User id: 3, name: "Foo", age: 21, ...>, #<User id: 2, name: "Oscar", age: 21, ...>, #<User id: 5, name: "Foo", age: 23, ...>]
     #
     # Passing in an array of attributes to group by is also supported.
+    #
     #   User.select([:id, :first_name]).group(:id, :first_name).first(3)
-    #   => [#<User id: 1, first_name: "Bill">, #<User id: 2, first_name: "Earl">, #<User id: 3, first_name: "Beto">]
+    #   # => [#<User id: 1, first_name: "Bill">, #<User id: 2, first_name: "Earl">, #<User id: 3, first_name: "Beto">]
     def group(*args)
       check_if_method_has_arguments!(:group, args)
       spawn.group!(*args)
@@ -286,22 +290,22 @@ module ActiveRecord
     # Allows to specify an order attribute:
     #
     #   User.order(:name)
-    #   => SELECT "users".* FROM "users" ORDER BY "users"."name" ASC
+    #   # SELECT "users".* FROM "users" ORDER BY "users"."name" ASC
     #
     #   User.order(email: :desc)
-    #   => SELECT "users".* FROM "users" ORDER BY "users"."email" DESC
+    #   # SELECT "users".* FROM "users" ORDER BY "users"."email" DESC
     #
     #   User.order(:name, email: :desc)
-    #   => SELECT "users".* FROM "users" ORDER BY "users"."name" ASC, "users"."email" DESC
+    #   # SELECT "users".* FROM "users" ORDER BY "users"."name" ASC, "users"."email" DESC
     #
     #   User.order('name')
-    #   => SELECT "users".* FROM "users" ORDER BY name
+    #   # SELECT "users".* FROM "users" ORDER BY name
     #
     #   User.order('name DESC')
-    #   => SELECT "users".* FROM "users" ORDER BY name DESC
+    #   # SELECT "users".* FROM "users" ORDER BY name DESC
     #
     #   User.order('name DESC, email')
-    #   => SELECT "users".* FROM "users" ORDER BY name DESC, email
+    #   # SELECT "users".* FROM "users" ORDER BY name DESC, email
     def order(*args)
       check_if_method_has_arguments!(:order, args)
       spawn.order!(*args)
@@ -353,15 +357,15 @@ module ActiveRecord
     #   User.order('email DESC').select('id').where(name: "John")
     #       .unscope(:order, :select, :where) == User.all
     #
-    # One can additionally pass a hash as an argument to unscope specific :where values.
+    # One can additionally pass a hash as an argument to unscope specific +:where+ values.
     # This is done by passing a hash with a single key-value pair. The key should be
-    # :where and the value should be the where value to unscope. For example:
+    # +:where+ and the value should be the where value to unscope. For example:
     #
     #   User.where(name: "John", active: true).unscope(where: :name)
     #       == User.where(active: true)
     #
-    # This method is similar to <tt>except</tt>, but unlike
-    # <tt>except</tt>, it persists across merges:
+    # This method is similar to #except, but unlike
+    # #except, it persists across merges:
     #
     #   User.order('email').merge(User.except(:order))
     #       == User.order('email')
@@ -371,7 +375,7 @@ module ActiveRecord
     #
     # This means it can be used in association definitions:
     #
-    #   has_many :comments, -> { unscope where: :trashed }
+    #   has_many :comments, -> { unscope(where: :trashed) }
     #
     def unscope(*args)
       check_if_method_has_arguments!(:unscope, args)
@@ -392,9 +396,8 @@ module ActiveRecord
               raise ArgumentError, "Hash arguments in .unscope(*args) must have :where as the key."
             end
 
-            Array(target_value).each do |val|
-              where_unscoping(val)
-            end
+            target_values = Array(target_value).map(&:to_s)
+            self.where_clause = where_clause.except(*target_values)
           end
         else
           raise ArgumentError, "Unrecognized scoping: #{args.inspect}. Use .unscope(where: :attribute_name) or .unscope(:order), for example."
@@ -407,12 +410,12 @@ module ActiveRecord
     # Performs a joins on +args+:
     #
     #   User.joins(:posts)
-    #   => SELECT "users".* FROM "users" INNER JOIN "posts" ON "posts"."user_id" = "users"."id"
+    #   # SELECT "users".* FROM "users" INNER JOIN "posts" ON "posts"."user_id" = "users"."id"
     #
     # You can use strings in order to customize your joins:
     #
     #   User.joins("LEFT JOIN bookmarks ON bookmarks.bookmarkable_type = 'Post' AND bookmarks.user_id = users.id")
-    #   => SELECT "users".* FROM "users" LEFT JOIN bookmarks ON bookmarks.bookmarkable_type = 'Post' AND bookmarks.user_id = users.id
+    #   # SELECT "users".* FROM "users" LEFT JOIN bookmarks ON bookmarks.bookmarkable_type = 'Post' AND bookmarks.user_id = users.id
     def joins(*args)
       check_if_method_has_arguments!(:joins, args)
       spawn.joins!(*args)
@@ -425,15 +428,6 @@ module ActiveRecord
       self
     end
 
-    def bind(value) # :nodoc:
-      spawn.bind!(value)
-    end
-
-    def bind!(value) # :nodoc:
-      self.bind_values += [value]
-      self
-    end
-
     # Returns a new relation, which is the result of filtering the current relation
     # according to the conditions in the arguments.
     #
@@ -477,7 +471,7 @@ module ActiveRecord
     # than the previous methods; you are responsible for ensuring that the values in the template
     # are properly quoted. The values are passed to the connector for quoting, but the caller
     # is responsible for ensuring they are enclosed in quotes in the resulting SQL. After quoting,
-    # the values are inserted using the same escapes as the Ruby core method <tt>Kernel::sprintf</tt>.
+    # the values are inserted using the same escapes as the Ruby core method +Kernel::sprintf+.
     #
     #   User.where(["name = '%s' and email = '%s'", "Joe", "joe@example.com"])
     #   # SELECT * FROM users WHERE name = 'Joe' AND email = 'joe@example.com';
@@ -554,7 +548,7 @@ module ActiveRecord
     # If the condition is any blank-ish object, then #where is a no-op and returns
     # the current relation.
     def where(opts = :chain, *rest)
-      if opts == :chain
+      if :chain == opts
         WhereChain.new(spawn)
       elsif opts.blank?
         self
@@ -564,27 +558,54 @@ module ActiveRecord
     end
 
     def where!(opts, *rest) # :nodoc:
-      if Hash === opts
-        opts = sanitize_forbidden_attributes(opts)
-        references!(PredicateBuilder.references(opts))
-      end
-
-      self.where_values += build_where(opts, rest)
+      opts = sanitize_forbidden_attributes(opts)
+      references!(PredicateBuilder.references(opts)) if Hash === opts
+      self.where_clause += where_clause_factory.build(opts, rest)
       self
     end
 
     # Allows you to change a previously set where condition for a given attribute, instead of appending to that condition.
     #
-    #   Post.where(trashed: true).where(trashed: false)                       # => WHERE `trashed` = 1 AND `trashed` = 0
-    #   Post.where(trashed: true).rewhere(trashed: false)                     # => WHERE `trashed` = 0
-    #   Post.where(active: true).where(trashed: true).rewhere(trashed: false) # => WHERE `active` = 1 AND `trashed` = 0
+    #   Post.where(trashed: true).where(trashed: false)
+    #   # WHERE `trashed` = 1 AND `trashed` = 0
+    #
+    #   Post.where(trashed: true).rewhere(trashed: false)
+    #   # WHERE `trashed` = 0
+    #
+    #   Post.where(active: true).where(trashed: true).rewhere(trashed: false)
+    #   # WHERE `active` = 1 AND `trashed` = 0
     #
-    # This is short-hand for unscope(where: conditions.keys).where(conditions). Note that unlike reorder, we're only unscoping
-    # the named conditions -- not the entire where statement.
+    # This is short-hand for <tt>unscope(where: conditions.keys).where(conditions)</tt>.
+    # Note that unlike reorder, we're only unscoping the named conditions -- not the entire where statement.
     def rewhere(conditions)
       unscope(where: conditions.keys).where(conditions)
     end
 
+    # Returns a new relation, which is the logical union of this relation and the one passed as an
+    # argument.
+    #
+    # The two relations must be structurally compatible: they must be scoping the same model, and
+    # they must differ only by #where (if no #group has been defined) or #having (if a #group is
+    # present). Neither relation may have a #limit, #offset, or #distinct set.
+    #
+    #    Post.where("id = 1").or(Post.where("id = 2"))
+    #    # SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'id = 2'))
+    #
+    def or(other)
+      spawn.or!(other)
+    end
+
+    def or!(other) # :nodoc:
+      unless structurally_compatible_for_or?(other)
+        raise ArgumentError, 'Relation passed to #or must be structurally compatible'
+      end
+
+      self.where_clause = self.where_clause.or(other.where_clause)
+      self.having_clause = self.having_clause.or(other.having_clause)
+
+      self
+    end
+
     # Allows to specify a HAVING clause. Note that you can't use HAVING
     # without also specifying a GROUP clause.
     #
@@ -594,9 +615,10 @@ module ActiveRecord
     end
 
     def having!(opts, *rest) # :nodoc:
+      opts = sanitize_forbidden_attributes(opts)
       references!(PredicateBuilder.references(opts)) if Hash === opts
 
-      self.having_values += build_where(opts, rest)
+      self.having_clause += having_clause_factory.build(opts, rest)
       self
     end
 
@@ -631,7 +653,7 @@ module ActiveRecord
     end
 
     # Specifies locking settings (default to +true+). For more information
-    # on locking, please see +ActiveRecord::Locking+.
+    # on locking, please see ActiveRecord::Locking.
     def lock(locks = true)
       spawn.lock!(locks)
     end
@@ -662,7 +684,7 @@ module ActiveRecord
     # For example:
     #
     #   @posts = current_user.visible_posts.where(name: params[:name])
-    #   # => the visible_posts method is expected to return a chainable Relation
+    #   # the visible_posts method is expected to return a chainable Relation
     #
     #   def visible_posts
     #     case role
@@ -688,7 +710,7 @@ module ActiveRecord
     #
     #   users = User.readonly
     #   users.first.save
-    #   => ActiveRecord::ReadOnlyRecord: ActiveRecord::ReadOnlyRecord
+    #   => ActiveRecord::ReadOnlyRecord: User is marked as readonly
     def readonly(value = true)
       spawn.readonly!(value)
     end
@@ -707,7 +729,7 @@ module ActiveRecord
     #   users = users.create_with(name: 'DHH')
     #   users.new.name # => 'DHH'
     #
-    # You can pass +nil+ to +create_with+ to reset attributes:
+    # You can pass +nil+ to #create_with to reset attributes:
     #
     #   users = users.create_with(nil)
     #   users.new.name # => 'Oscar'
@@ -729,42 +751,40 @@ module ActiveRecord
     # Specifies table from which the records will be fetched. For example:
     #
     #   Topic.select('title').from('posts')
-    #   # => SELECT title FROM posts
+    #   # SELECT title FROM posts
     #
     # Can accept other relation objects. For example:
     #
     #   Topic.select('title').from(Topic.approved)
-    #   # => SELECT title FROM (SELECT * FROM topics WHERE approved = 't') subquery
+    #   # SELECT title FROM (SELECT * FROM topics WHERE approved = 't') subquery
     #
     #   Topic.select('a.title').from(Topic.approved, :a)
-    #   # => SELECT a.title FROM (SELECT * FROM topics WHERE approved = 't') a
+    #   # SELECT a.title FROM (SELECT * FROM topics WHERE approved = 't') a
     #
     def from(value, subquery_name = nil)
       spawn.from!(value, subquery_name)
     end
 
     def from!(value, subquery_name = nil) # :nodoc:
-      self.from_value = [value, subquery_name]
-      if value.is_a? Relation
-        self.bind_values = value.arel.bind_values + value.bind_values + bind_values
-      end
+      self.from_clause = Relation::FromClause.new(value, subquery_name)
       self
     end
 
     # Specifies whether the records should be unique or not. For example:
     #
     #   User.select(:name)
-    #   # => Might return two records with the same name
+    #   # Might return two records with the same name
     #
     #   User.select(:name).distinct
-    #   # => Returns 1 record per distinct name
+    #   # Returns 1 record per distinct name
     #
     #   User.select(:name).distinct.distinct(false)
-    #   # => You can also remove the uniqueness
+    #   # You can also remove the uniqueness
     def distinct(value = true)
       spawn.distinct!(value)
     end
     alias uniq distinct
+    deprecate uniq: :distinct
 
     # Like #distinct, but modifies relation in place.
     def distinct!(value = true) # :nodoc:
@@ -772,6 +792,7 @@ module ActiveRecord
       self
     end
     alias uniq! distinct!
+    deprecate uniq!: :distinct!
 
     # Used to extend a scope with additional methods, either through
     # a module or through a block provided.
@@ -858,21 +879,18 @@ module ActiveRecord
 
       build_joins(arel, joins_values.flatten) unless joins_values.empty?
 
-      collapse_wheres(arel, (where_values - [''])) #TODO: Add uniq with real value comparison / ignore uniqs that have binds
-
-      arel.having(*having_values.uniq.reject(&:blank?)) unless having_values.empty?
-
+      arel.where(where_clause.ast) unless where_clause.empty?
+      arel.having(having_clause.ast) unless having_clause.empty?
       arel.take(connection.sanitize_limit(limit_value)) if limit_value
       arel.skip(offset_value.to_i) if offset_value
-
-      arel.group(*group_values.uniq.reject(&:blank?)) unless group_values.empty?
+      arel.group(*arel_columns(group_values.uniq.reject(&:blank?))) unless group_values.empty?
 
       build_order(arel)
 
-      build_select(arel, select_values.uniq)
+      build_select(arel)
 
       arel.distinct(distinct_value)
-      arel.from(build_from) if from_value
+      arel.from(build_from) unless from_clause.empty?
       arel.lock(lock_value) if lock_value
 
       arel
@@ -883,114 +901,24 @@ module ActiveRecord
         raise ArgumentError, "Called unscope() with invalid unscoping argument ':#{scope}'. Valid arguments are :#{VALID_UNSCOPING_VALUES.to_a.join(", :")}."
       end
 
-      single_val_method = Relation::SINGLE_VALUE_METHODS.include?(scope)
-      unscope_code = "#{scope}_value#{'s' unless single_val_method}="
+      clause_method = Relation::CLAUSE_METHODS.include?(scope)
+      multi_val_method = Relation::MULTI_VALUE_METHODS.include?(scope)
+      if clause_method
+        unscope_code = "#{scope}_clause="
+      else
+        unscope_code = "#{scope}_value#{'s' if multi_val_method}="
+      end
 
       case scope
       when :order
         result = []
-      when :where
-        self.bind_values = []
       else
-        result = [] unless single_val_method
+        result = [] if multi_val_method
       end
 
       self.send(unscope_code, result)
     end
 
-    def where_unscoping(target_value)
-      target_value = target_value.to_s
-
-      where_values.reject! do |rel|
-        case rel
-        when Arel::Nodes::Between, Arel::Nodes::In, Arel::Nodes::NotIn, Arel::Nodes::Equality, Arel::Nodes::NotEqual, Arel::Nodes::LessThanOrEqual, Arel::Nodes::GreaterThanOrEqual
-          subrelation = (rel.left.kind_of?(Arel::Attributes::Attribute) ? rel.left : rel.right)
-          subrelation.name.to_s == target_value
-        end
-      end
-
-      bind_values.reject! { |col,_| col.name == target_value }
-    end
-
-    def custom_join_ast(table, joins)
-      joins = joins.reject(&:blank?)
-
-      return [] if joins.empty?
-
-      joins.map! do |join|
-        case join
-        when Array
-          join = Arel.sql(join.join(' ')) if array_of_strings?(join)
-        when String
-          join = Arel.sql(join)
-        end
-        table.create_string_join(join)
-      end
-    end
-
-    def collapse_wheres(arel, wheres)
-      predicates = wheres.map do |where|
-        next where if ::Arel::Nodes::Equality === where
-        where = Arel.sql(where) if String === where
-        Arel::Nodes::Grouping.new(where)
-      end
-
-      arel.where(Arel::Nodes::And.new(predicates)) if predicates.present?
-    end
-
-    def build_where(opts, other = [])
-      case opts
-      when String, Array
-        [@klass.send(:sanitize_sql, other.empty? ? opts : ([opts] + other))]
-      when Hash
-        opts = predicate_builder.resolve_column_aliases(opts)
-
-        tmp_opts, bind_values = create_binds(opts)
-        self.bind_values += bind_values
-
-        attributes = @klass.send(:expand_hash_conditions_for_aggregates, tmp_opts)
-        add_relations_to_bind_values(attributes)
-
-        predicate_builder.build_from_hash(attributes)
-      else
-        [opts]
-      end
-    end
-
-    def create_binds(opts)
-      bindable, non_binds = opts.partition do |column, value|
-        case value
-        when String, Integer, ActiveRecord::StatementCache::Substitute
-          @klass.columns_hash.include? column.to_s
-        else
-          false
-        end
-      end
-
-      association_binds, non_binds = non_binds.partition do |column, value|
-        value.is_a?(Hash) && association_for_table(column)
-      end
-
-      new_opts = {}
-      binds = []
-
-      bindable.each do |(column,value)|
-        binds.push [@klass.columns_hash[column.to_s], value]
-        new_opts[column] = connection.substitute_at(column)
-      end
-
-      association_binds.each do |(column, value)|
-        association_relation = association_for_table(column).klass.send(:relation)
-        association_new_opts, association_bind = association_relation.send(:create_binds, value)
-        new_opts[column] = association_new_opts
-        binds += association_bind
-      end
-
-      non_binds.each { |column,value| new_opts[column] = value }
-
-      [new_opts, binds]
-    end
-
     def association_for_table(table_name)
       table_name = table_name.to_s
       @klass._reflect_on_association(table_name) ||
@@ -998,7 +926,8 @@ module ActiveRecord
     end
 
     def build_from
-      opts, name = from_value
+      opts = from_clause.value
+      name = from_clause.name
       case opts
       when Relation
         name ||= 'subquery'
@@ -1023,13 +952,14 @@ module ActiveRecord
           raise 'unknown class: %s' % join.class.name
         end
       end
+      buckets.default = []
 
-      association_joins         = buckets[:association_join] || []
-      stashed_association_joins = buckets[:stashed_join] || []
-      join_nodes                = (buckets[:join_node] || []).uniq
-      string_joins              = (buckets[:string_join] || []).map(&:strip).uniq
+      association_joins         = buckets[:association_join]
+      stashed_association_joins = buckets[:stashed_join]
+      join_nodes                = buckets[:join_node].uniq
+      string_joins              = buckets[:string_join].map(&:strip).uniq
 
-      join_list = join_nodes + custom_join_ast(manager, string_joins)
+      join_list = join_nodes + convert_join_strings_to_ast(manager, string_joins)
 
       join_dependency = ActiveRecord::Associations::JoinDependency.new(
         @klass,
@@ -1049,22 +979,33 @@ module ActiveRecord
       manager
     end
 
-    def build_select(arel, selects)
-      if !selects.empty?
-        expanded_select = selects.map do |field|
-          if (Symbol === field || String === field) && columns_hash.key?(field.to_s)
-            arel_table[field]
-          else
-            field
-          end
-        end
+    def convert_join_strings_to_ast(table, joins)
+      joins
+        .flatten
+        .reject(&:blank?)
+        .map { |join| table.create_string_join(Arel.sql(join)) }
+    end
 
-        arel.project(*expanded_select)
+    def build_select(arel)
+      if select_values.any?
+        arel.project(*arel_columns(select_values.uniq))
       else
         arel.project(@klass.arel_table[Arel.star])
       end
     end
 
+    def arel_columns(columns)
+      columns.map do |field|
+        if (Symbol === field || String === field) && columns_hash.key?(field.to_s) && !from_clause.value
+          arel_table[field]
+        elsif Symbol === field
+          connection.quote_table_name(field.to_s)
+        else
+          field
+        end
+      end
+    end
+
     def reverse_sql_order(order_query)
       order_query = ["#{quoted_table_name}.#{quoted_primary_key} ASC"] if order_query.empty?
 
@@ -1083,10 +1024,6 @@ module ActiveRecord
       end
     end
 
-    def array_of_strings?(o)
-      o.is_a?(Array) && o.all? { |obj| obj.is_a?(String) }
-    end
-
     def build_order(arel)
       orders = order_values.uniq
       orders.reject!(&:blank?)
@@ -1138,8 +1075,8 @@ module ActiveRecord
     #
     # Example:
     #
-    #    Post.references()   # => raises an error
-    #    Post.references([]) # => does not raise an error
+    #    Post.references()   # raises an error
+    #    Post.references([]) # does not raise an error
     #
     # This particular method should be called with a method_name and the args
     # passed into that method as an input. For example:
@@ -1154,16 +1091,24 @@ module ActiveRecord
       end
     end
 
-    def add_relations_to_bind_values(attributes)
-      if attributes.is_a?(Hash)
-        attributes.each_value do |value|
-          if value.is_a?(ActiveRecord::Relation)
-            self.bind_values += value.arel.bind_values + value.bind_values
-          else
-            add_relations_to_bind_values(value)
-          end
-        end
-      end
+    def structurally_compatible_for_or?(other)
+      Relation::SINGLE_VALUE_METHODS.all? { |m| send("#{m}_value") == other.send("#{m}_value") } &&
+        (Relation::MULTI_VALUE_METHODS - [:extending]).all? { |m| send("#{m}_values") == other.send("#{m}_values") } &&
+        (Relation::CLAUSE_METHODS - [:having, :where]).all? { |m| send("#{m}_clause") != other.send("#{m}_clause") }
+    end
+
+    def new_where_clause
+      Relation::WhereClause.empty
+    end
+    alias new_having_clause new_where_clause
+
+    def where_clause_factory
+      @where_clause_factory ||= Relation::WhereClauseFactory.new(klass, predicate_builder)
+    end
+    alias having_clause_factory where_clause_factory
+
+    def new_from_clause
+      Relation::FromClause.empty
     end
   end
 end
diff --git a/activerecord/lib/active_record/relation/record_fetch_warning.rb b/activerecord/lib/active_record/relation/record_fetch_warning.rb
new file mode 100644
index 0000000000..14e1bf89fa
--- /dev/null
+++ b/activerecord/lib/active_record/relation/record_fetch_warning.rb
@@ -0,0 +1,49 @@
+module ActiveRecord
+  class Relation
+    module RecordFetchWarning
+      # When this module is prepended to ActiveRecord::Relation and
+      # `config.active_record.warn_on_records_fetched_greater_than` is
+      # set to an integer, if the number of records a query returns is
+      # greater than the value of `warn_on_records_fetched_greater_than`,
+      # a warning is logged. This allows for the detection of queries that
+      # return a large number of records, which could cause memory bloat.
+      #
+      # In most cases, fetching large number of records can be performed
+      # efficiently using the ActiveRecord::Batches methods.
+      # See active_record/lib/relation/batches.rb for more information.
+      def exec_queries
+        QueryRegistry.reset
+
+        super.tap do
+          if logger && warn_on_records_fetched_greater_than
+            if @records.length > warn_on_records_fetched_greater_than
+              logger.warn "Query fetched #{@records.size} #{@klass} records: #{QueryRegistry.queries.join(";")}"
+            end
+          end
+        end
+      end
+
+      ActiveSupport::Notifications.subscribe("sql.active_record") do |*args|
+        payload = args.last
+
+        QueryRegistry.queries << payload[:sql]
+      end
+
+      class QueryRegistry # :nodoc:
+        extend ActiveSupport::PerThreadRegistry
+
+        attr_accessor :queries
+
+        def initialize
+          reset
+        end
+
+        def reset
+          @queries = []
+        end
+      end
+    end
+  end
+end
+
+ActiveRecord::Relation.prepend ActiveRecord::Relation::RecordFetchWarning
diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 01bddea6c9..5c3318651a 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -10,7 +10,7 @@ module ActiveRecord
       clone
     end
 
-    # Merges in the conditions from <tt>other</tt>, if <tt>other</tt> is an <tt>ActiveRecord::Relation</tt>.
+    # Merges in the conditions from <tt>other</tt>, if <tt>other</tt> is an ActiveRecord::Relation.
     # Returns an array representing the intersection of the resulting records with <tt>other</tt>, if <tt>other</tt> is an array.
     #   Post.where(published: true).joins(:comments).merge( Comment.where(spam: false) )
     #   # Performs a single join query with both where conditions.
@@ -32,7 +32,7 @@ module ActiveRecord
       elsif other
         spawn.merge!(other)
       else
-        self
+        raise ArgumentError, "invalid argument: #{other.inspect}."
       end
     end
 
@@ -58,9 +58,6 @@ module ActiveRecord
     #   Post.order('id asc').only(:where)         # discards the order condition
     #   Post.order('id asc').only(:where, :order) # uses the specified order
     def only(*onlies)
-      if onlies.any? { |o| o == :where }
-        onlies << :bind
-      end
       relation_with values.slice(*onlies)
     end
 
diff --git a/activerecord/lib/active_record/relation/where_clause.rb b/activerecord/lib/active_record/relation/where_clause.rb
new file mode 100644
index 0000000000..1f000b3f0f
--- /dev/null
+++ b/activerecord/lib/active_record/relation/where_clause.rb
@@ -0,0 +1,173 @@
+module ActiveRecord
+  class Relation
+    class WhereClause # :nodoc:
+      attr_reader :binds
+
+      delegate :any?, :empty?, to: :predicates
+
+      def initialize(predicates, binds)
+        @predicates = predicates
+        @binds = binds
+      end
+
+      def +(other)
+        WhereClause.new(
+          predicates + other.predicates,
+          binds + other.binds,
+        )
+      end
+
+      def merge(other)
+        WhereClause.new(
+          predicates_unreferenced_by(other) + other.predicates,
+          non_conflicting_binds(other) + other.binds,
+        )
+      end
+
+      def except(*columns)
+        WhereClause.new(
+          predicates_except(columns),
+          binds_except(columns),
+        )
+      end
+
+      def or(other)
+        if empty?
+          self
+        elsif other.empty?
+          other
+        else
+          WhereClause.new(
+            [ast.or(other.ast)],
+            binds + other.binds
+          )
+        end
+      end
+
+      def to_h(table_name = nil)
+        equalities = predicates.grep(Arel::Nodes::Equality)
+        if table_name
+          equalities = equalities.select do |node|
+            node.left.relation.name == table_name
+          end
+        end
+
+        binds = self.binds.map { |attr| [attr.name, attr.value] }.to_h
+
+        equalities.map { |node|
+          name = node.left.name
+          [name, binds.fetch(name.to_s) {
+            case node.right
+            when Array then node.right.map(&:val)
+            when Arel::Nodes::Casted, Arel::Nodes::Quoted
+              node.right.val
+            end
+          }]
+        }.to_h
+      end
+
+      def ast
+        Arel::Nodes::And.new(predicates_with_wrapped_sql_literals)
+      end
+
+      def ==(other)
+        other.is_a?(WhereClause) &&
+          predicates == other.predicates &&
+          binds == other.binds
+      end
+
+      def invert
+        WhereClause.new(inverted_predicates, binds)
+      end
+
+      def self.empty
+        new([], [])
+      end
+
+      protected
+
+      attr_reader :predicates
+
+      def referenced_columns
+        @referenced_columns ||= begin
+          equality_nodes = predicates.select { |n| equality_node?(n) }
+          Set.new(equality_nodes, &:left)
+        end
+      end
+
+      private
+
+      def predicates_unreferenced_by(other)
+        predicates.reject do |n|
+          equality_node?(n) && other.referenced_columns.include?(n.left)
+        end
+      end
+
+      def equality_node?(node)
+        node.respond_to?(:operator) && node.operator == :==
+      end
+
+      def non_conflicting_binds(other)
+        conflicts = referenced_columns & other.referenced_columns
+        conflicts.map! { |node| node.name.to_s }
+        binds.reject { |attr| conflicts.include?(attr.name) }
+      end
+
+      def inverted_predicates
+        predicates.map { |node| invert_predicate(node) }
+      end
+
+      def invert_predicate(node)
+        case node
+        when NilClass
+          raise ArgumentError, 'Invalid argument for .where.not(), got nil.'
+        when Arel::Nodes::In
+          Arel::Nodes::NotIn.new(node.left, node.right)
+        when Arel::Nodes::Equality
+          Arel::Nodes::NotEqual.new(node.left, node.right)
+        when String
+          Arel::Nodes::Not.new(Arel::Nodes::SqlLiteral.new(node))
+        else
+          Arel::Nodes::Not.new(node)
+        end
+      end
+
+      def predicates_except(columns)
+        predicates.reject do |node|
+          case node
+          when Arel::Nodes::Between, Arel::Nodes::In, Arel::Nodes::NotIn, Arel::Nodes::Equality, Arel::Nodes::NotEqual, Arel::Nodes::LessThan, Arel::Nodes::LessThanOrEqual, Arel::Nodes::GreaterThan, Arel::Nodes::GreaterThanOrEqual
+            subrelation = (node.left.kind_of?(Arel::Attributes::Attribute) ? node.left : node.right)
+            columns.include?(subrelation.name.to_s)
+          end
+        end
+      end
+
+      def binds_except(columns)
+        binds.reject do |attr|
+          columns.include?(attr.name)
+        end
+      end
+
+      def predicates_with_wrapped_sql_literals
+        non_empty_predicates.map do |node|
+          if Arel::Nodes::Equality === node
+            node
+          else
+            wrap_sql_literal(node)
+          end
+        end
+      end
+
+      def non_empty_predicates
+        predicates - ['']
+      end
+
+      def wrap_sql_literal(node)
+        if ::String === node
+          node = Arel.sql(node)
+        end
+        Arel::Nodes::Grouping.new(node)
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/relation/where_clause_factory.rb b/activerecord/lib/active_record/relation/where_clause_factory.rb
new file mode 100644
index 0000000000..a81ff98e49
--- /dev/null
+++ b/activerecord/lib/active_record/relation/where_clause_factory.rb
@@ -0,0 +1,37 @@
+module ActiveRecord
+  class Relation
+    class WhereClauseFactory # :nodoc:
+      def initialize(klass, predicate_builder)
+        @klass = klass
+        @predicate_builder = predicate_builder
+      end
+
+      def build(opts, other)
+        binds = []
+
+        case opts
+        when String, Array
+          parts = [klass.send(:sanitize_sql, other.empty? ? opts : ([opts] + other))]
+        when Hash
+          attributes = predicate_builder.resolve_column_aliases(opts)
+          attributes = klass.send(:expand_hash_conditions_for_aggregates, attributes)
+          attributes.stringify_keys!
+
+          attributes, binds = predicate_builder.create_binds(attributes)
+
+          parts = predicate_builder.build_from_hash(attributes)
+        when Arel::Nodes::Node
+          parts = [opts]
+        else
+          raise ArgumentError, "Unsupported argument type: #{opts} (#{opts.class})"
+        end
+
+        WhereClause.new(parts, binds)
+      end
+
+      protected
+
+      attr_reader :klass, :predicate_builder
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/result.rb b/activerecord/lib/active_record/result.rb
index 3a3e65ef32..8e6cd6c82f 100644
--- a/activerecord/lib/active_record/result.rb
+++ b/activerecord/lib/active_record/result.rb
@@ -1,7 +1,8 @@
 module ActiveRecord
   ###
-  # This class encapsulates a Result returned from calling +exec_query+ on any
-  # database connection adapter. For example:
+  # This class encapsulates a result returned from calling
+  # {#exec_query}[rdoc-ref:ConnectionAdapters::DatabaseStatements#exec_query]
+  # on any database connection adapter. For example:
   #
   #   result = ActiveRecord::Base.connection.exec_query('SELECT id, title, body FROM posts')
   #   result # => #<ActiveRecord::Result:0xdeadbeef>
@@ -81,7 +82,7 @@ module ActiveRecord
     def cast_values(type_overrides = {}) # :nodoc:
       types = columns.map { |name| column_type(name, type_overrides) }
       result = rows.map do |values|
-        types.zip(values).map { |type, value| type.type_cast_from_database(value) }
+        types.zip(values).map { |type, value| type.deserialize(value) }
       end
 
       columns.one? ? result.map!(&:first) : result
diff --git a/activerecord/lib/active_record/runtime_registry.rb b/activerecord/lib/active_record/runtime_registry.rb
index 9d605b826a..56e88bc661 100644
--- a/activerecord/lib/active_record/runtime_registry.rb
+++ b/activerecord/lib/active_record/runtime_registry.rb
@@ -7,7 +7,7 @@ module ActiveRecord
   #
   # returns the connection handler local to the current thread.
   #
-  # See the documentation of <tt>ActiveSupport::PerThreadRegistry</tt>
+  # See the documentation of ActiveSupport::PerThreadRegistry
   # for further details.
   class RuntimeRegistry # :nodoc:
     extend ActiveSupport::PerThreadRegistry
diff --git a/activerecord/lib/active_record/sanitization.rb b/activerecord/lib/active_record/sanitization.rb
index 313e767dcb..1cf4b09bf3 100644
--- a/activerecord/lib/active_record/sanitization.rb
+++ b/activerecord/lib/active_record/sanitization.rb
@@ -3,25 +3,31 @@ module ActiveRecord
     extend ActiveSupport::Concern
 
     module ClassMethods
-      # Used to sanitize objects before they're used in an SQL SELECT statement. Delegates to <tt>connection.quote</tt>.
-      def sanitize(object) #:nodoc:
+      # Used to sanitize objects before they're used in an SQL SELECT statement.
+      # Delegates to {connection.quote}[rdoc-ref:ConnectionAdapters::Quoting#quote].
+      def sanitize(object) # :nodoc:
         connection.quote(object)
       end
       alias_method :quote_value, :sanitize
 
       protected
 
-      # Accepts an array, hash, or string of SQL conditions and sanitizes
+      # Accepts an array or string of SQL conditions and sanitizes
       # them into a valid SQL fragment for a WHERE clause.
-      #   ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
-      #   { name: "foo'bar", group_id: 4 }  returns "name='foo''bar' and group_id='4'"
-      #   "name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"
-      def sanitize_sql_for_conditions(condition, table_name = self.table_name)
+      #
+      #   sanitize_sql_for_conditions(["name=? and group_id=?", "foo'bar", 4])
+      #   # => "name='foo''bar' and group_id=4"
+      #
+      #   sanitize_sql_for_conditions(["name='%s' and group_id='%s'", "foo'bar", 4])
+      #   # => "name='foo''bar' and group_id='4'"
+      #
+      #   sanitize_sql_for_conditions("name='foo''bar' and group_id='4'")
+      #   # => "name='foo''bar' and group_id='4'"
+      def sanitize_sql_for_conditions(condition)
         return nil if condition.blank?
 
         case condition
         when Array; sanitize_sql_array(condition)
-        when Hash;  sanitize_sql_hash_for_conditions(condition, table_name)
         else        condition
         end
       end
@@ -30,7 +36,15 @@ module ActiveRecord
 
       # Accepts an array, hash, or string of SQL conditions and sanitizes
       # them into a valid SQL fragment for a SET clause.
-      #   { name: nil, group_id: 4 }  returns "name = NULL , group_id='4'"
+      #
+      #   sanitize_sql_for_assignment(["name=? and group_id=?", nil, 4])
+      #   # => "name=NULL and group_id=4"
+      #
+      #   Post.send(:sanitize_sql_for_assignment, { name: nil, group_id: 4 })
+      #   # => "`posts`.`name` = NULL, `posts`.`group_id` = 4"
+      #
+      #   sanitize_sql_for_assignment("name=NULL and group_id='4'")
+      #   # => "name=NULL and group_id='4'"
       def sanitize_sql_for_assignment(assignments, default_table_name = self.table_name)
         case assignments
         when Array; sanitize_sql_array(assignments)
@@ -40,16 +54,20 @@ module ActiveRecord
       end
 
       # Accepts a hash of SQL conditions and replaces those attributes
-      # that correspond to a +composed_of+ relationship with their expanded
-      # aggregate attribute values.
+      # that correspond to a {#composed_of}[rdoc-ref:Aggregations::ClassMethods#composed_of]
+      # relationship with their expanded aggregate attribute values.
+      #
       # Given:
-      #     class Person < ActiveRecord::Base
-      #       composed_of :address, class_name: "Address",
-      #         mapping: [%w(address_street street), %w(address_city city)]
-      #     end
+      #
+      #   class Person < ActiveRecord::Base
+      #     composed_of :address, class_name: "Address",
+      #       mapping: [%w(address_street street), %w(address_city city)]
+      #   end
+      #
       # Then:
-      #     { address: Address.new("813 abc st.", "chicago") }
-      #       # => { address_street: "813 abc st.", address_city: "chicago" }
+      #
+      #   { address: Address.new("813 abc st.", "chicago") }
+      #   # => { address_street: "813 abc st.", address_city: "chicago" }
       def expand_hash_conditions_for_aggregates(attrs)
         expanded_attrs = {}
         attrs.each do |attr, value|
@@ -70,18 +88,31 @@ module ActiveRecord
       end
 
       # Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.
-      #   { status: nil, group_id: 1 }
-      #     # => "status = NULL , group_id = 1"
+      #
+      #   sanitize_sql_hash_for_assignment({ status: nil, group_id: 1 }, "posts")
+      #   # => "`posts`.`status` = NULL, `posts`.`group_id` = 1"
       def sanitize_sql_hash_for_assignment(attrs, table)
         c = connection
         attrs.map do |attr, value|
-          value = type_for_attribute(attr.to_s).type_cast_for_database(value)
+          value = type_for_attribute(attr.to_s).serialize(value)
           "#{c.quote_table_name_for_assignment(table, attr)} = #{c.quote(value)}"
         end.join(', ')
       end
 
       # Sanitizes a +string+ so that it is safe to use within an SQL
-      # LIKE statement. This method uses +escape_character+ to escape all occurrences of "\", "_" and "%"
+      # LIKE statement. This method uses +escape_character+ to escape all occurrences of "\", "_" and "%".
+      #
+      #   sanitize_sql_like("100%")
+      #   # => "100\\%"
+      #
+      #   sanitize_sql_like("snake_cased_string")
+      #   # => "snake\\_cased\\_string"
+      #
+      #   sanitize_sql_like("100%", "!")
+      #   # => "100!%"
+      #
+      #   sanitize_sql_like("snake_cased_string", "!")
+      #   # => "snake!_cased!_string"
       def sanitize_sql_like(string, escape_character = "\\")
         pattern = Regexp.union(escape_character, "%", "_")
         string.gsub(pattern) { |x| [escape_character, x].join }
@@ -89,7 +120,12 @@ module ActiveRecord
 
       # Accepts an array of conditions. The array has each value
       # sanitized and interpolated into the SQL statement.
-      #   ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
+      #
+      #   sanitize_sql_array(["name=? and group_id=?", "foo'bar", 4])
+      #   # => "name='foo''bar' and group_id=4"
+      #
+      #   sanitize_sql_array(["name='%s' and group_id='%s'", "foo'bar", 4])
+      #   # => "name='foo''bar' and group_id='4'"
       def sanitize_sql_array(ary)
         statement, *values = ary
         if values.first.is_a?(Hash) && statement =~ /:\w+/
@@ -103,7 +139,7 @@ module ActiveRecord
         end
       end
 
-      def replace_bind_variables(statement, values) #:nodoc:
+      def replace_bind_variables(statement, values) # :nodoc:
         raise_if_bind_arity_mismatch(statement, statement.count('?'), values.size)
         bound = values.dup
         c = connection
@@ -112,7 +148,7 @@ module ActiveRecord
         end
       end
 
-      def replace_bind_variable(value, c = connection) #:nodoc:
+      def replace_bind_variable(value, c = connection) # :nodoc:
         if ActiveRecord::Relation === value
           value.to_sql
         else
@@ -120,10 +156,10 @@ module ActiveRecord
         end
       end
 
-      def replace_named_bind_variables(statement, bind_vars) #:nodoc:
-        statement.gsub(/(:?):([a-zA-Z]\w*)/) do
+      def replace_named_bind_variables(statement, bind_vars) # :nodoc:
+        statement.gsub(/(:?):([a-zA-Z]\w*)/) do |match|
           if $1 == ':' # skip postgresql casts
-            $& # return the whole match
+            match # return the whole match
           elsif bind_vars.include?(match = $2.to_sym)
             replace_bind_variable(bind_vars[match])
           else
@@ -132,7 +168,7 @@ module ActiveRecord
         end
       end
 
-      def quote_bound_value(value, c = connection) #:nodoc:
+      def quote_bound_value(value, c = connection) # :nodoc:
         if value.respond_to?(:map) && !value.acts_like?(:string)
           if value.respond_to?(:empty?) && value.empty?
             c.quote(nil)
@@ -144,7 +180,7 @@ module ActiveRecord
         end
       end
 
-      def raise_if_bind_arity_mismatch(statement, expected, provided) #:nodoc:
+      def raise_if_bind_arity_mismatch(statement, expected, provided) # :nodoc:
         unless expected == provided
           raise PreparedStatementInvalid, "wrong number of bind variables (#{provided} for #{expected}) in: #{statement}"
         end
diff --git a/activerecord/lib/active_record/schema.rb b/activerecord/lib/active_record/schema.rb
index 0a5546a760..31dd584538 100644
--- a/activerecord/lib/active_record/schema.rb
+++ b/activerecord/lib/active_record/schema.rb
@@ -1,5 +1,5 @@
 module ActiveRecord
-  # = Active Record Schema
+  # = Active Record \Schema
   #
   # Allows programmers to programmatically define a schema in a portable
   # DSL. This means you can define tables, indexes, etc. without using SQL
@@ -28,28 +28,11 @@ module ActiveRecord
   # ActiveRecord::Schema is only supported by database adapters that also
   # support migrations, the two features being very similar.
   class Schema < Migration
-
-    # Returns the migrations paths.
-    #
-    #   ActiveRecord::Schema.new.migrations_paths
-    #   # => ["db/migrate"] # Rails migration path by default.
-    def migrations_paths
-      ActiveRecord::Migrator.migrations_paths
-    end
-
-    def define(info, &block) # :nodoc:
-      instance_eval(&block)
-
-      unless info[:version].blank?
-        initialize_schema_migrations_table
-        connection.assume_migrated_upto_version(info[:version], migrations_paths)
-      end
-    end
-
     # Eval the given block. All methods available to the current connection
     # adapter are available within the block, so you can easily use the
-    # database definition DSL to build up your schema (+create_table+,
-    # +add_index+, etc.).
+    # database definition DSL to build up your schema (
+    # {create_table}[rdoc-ref:ConnectionAdapters::SchemaStatements#create_table],
+    # {add_index}[rdoc-ref:ConnectionAdapters::SchemaStatements#add_index], etc.).
     #
     # The +info+ hash is optional, and if given is used to define metadata
     # about the current schema (currently, only the schema's version):
@@ -60,5 +43,23 @@ module ActiveRecord
     def self.define(info={}, &block)
       new.define(info, &block)
     end
+
+    def define(info, &block) # :nodoc:
+      instance_eval(&block)
+
+      if info[:version].present?
+        initialize_schema_migrations_table
+        connection.assume_migrated_upto_version(info[:version], migrations_paths)
+      end
+    end
+
+    private
+      # Returns the migrations paths.
+      #
+      #   ActiveRecord::Schema.new.migrations_paths
+      #   # => ["db/migrate"] # Rails migration path by default.
+      def migrations_paths # :nodoc:
+        ActiveRecord::Migrator.migrations_paths
+      end
   end
 end
diff --git a/activerecord/lib/active_record/schema_dumper.rb b/activerecord/lib/active_record/schema_dumper.rb
index da95920571..2362dae9fc 100644
--- a/activerecord/lib/active_record/schema_dumper.rb
+++ b/activerecord/lib/active_record/schema_dumper.rb
@@ -1,5 +1,4 @@
 require 'stringio'
-require 'active_support/core_ext/big_decimal'
 
 module ActiveRecord
   # = Active Record Schema Dumper
@@ -90,7 +89,7 @@ HEADER
       end
 
       def tables(stream)
-        sorted_tables = @connection.tables.sort
+        sorted_tables = @connection.data_sources.sort - @connection.views
 
         sorted_tables.each do |table_name|
           table(table_name, stream) unless ignored?(table_name)
@@ -105,29 +104,43 @@ HEADER
       end
 
       def table(table, stream)
-        columns = @connection.columns(table)
+        columns = @connection.columns(table).map do |column|
+          column.instance_variable_set(:@table_name, table)
+          column
+        end
         begin
           tbl = StringIO.new
 
           # first dump primary key column
-          pk = @connection.primary_key(table)
+          if @connection.respond_to?(:primary_keys)
+            pk = @connection.primary_keys(table)
+            pk = pk.first unless pk.size > 1
+          else
+            pk = @connection.primary_key(table)
+          end
 
           tbl.print "  create_table #{remove_prefix_and_suffix(table).inspect}"
-          pkcol = columns.detect { |c| c.name == pk }
-          if pkcol
-            if pk != 'id'
-              tbl.print %Q(, primary_key: "#{pk}")
-            end
+
+          case pk
+          when String
+            tbl.print ", primary_key: #{pk.inspect}" unless pk == 'id'
+            pkcol = columns.detect { |c| c.name == pk }
             pkcolspec = @connection.column_spec_for_primary_key(pkcol)
             if pkcolspec
               pkcolspec.each do |key, value|
                 tbl.print ", #{key}: #{value}"
               end
             end
+          when Array
+            tbl.print ", primary_key: #{pk.inspect}"
           else
             tbl.print ", id: false"
           end
           tbl.print ", force: :cascade"
+
+          table_options = @connection.table_options(table)
+          tbl.print ", options: #{table_options.inspect}" unless table_options.blank?
+
           tbl.puts " do |t|"
 
           # then dump all non-primary key columns
@@ -165,11 +178,11 @@ HEADER
             tbl.puts
           end
 
+          indexes(table, tbl)
+
           tbl.puts "  end"
           tbl.puts
 
-          indexes(table, tbl)
-
           tbl.rewind
           stream.print tbl.read
         rescue => e
@@ -185,8 +198,7 @@ HEADER
         if (indexes = @connection.indexes(table)).any?
           add_index_statements = indexes.map do |index|
             statement_parts = [
-              "add_index #{remove_prefix_and_suffix(index.table).inspect}",
-              index.columns.inspect,
+              "t.index #{index.columns.inspect}",
               "name: #{index.name.inspect}",
             ]
             statement_parts << 'unique: true' if index.unique
@@ -200,11 +212,10 @@ HEADER
             statement_parts << "using: #{index.using.inspect}" if index.using
             statement_parts << "type: #{index.type.inspect}" if index.type
 
-            "  #{statement_parts.join(', ')}"
+            "    #{statement_parts.join(', ')}"
           end
 
           stream.puts add_index_statements.sort.join("\n")
-          stream.puts
         end
       end
 
@@ -243,7 +254,7 @@ HEADER
       end
 
       def ignored?(table_name)
-        ['schema_migrations', ignore_tables].flatten.any? do |ignored|
+        [ActiveRecord::Base.schema_migrations_table_name, ignore_tables].flatten.any? do |ignored|
           ignored === remove_prefix_and_suffix(table_name)
         end
       end
diff --git a/activerecord/lib/active_record/schema_migration.rb b/activerecord/lib/active_record/schema_migration.rb
index b5038104ac..b384529e75 100644
--- a/activerecord/lib/active_record/schema_migration.rb
+++ b/activerecord/lib/active_record/schema_migration.rb
@@ -1,9 +1,12 @@
 require 'active_record/scoping/default'
 require 'active_record/scoping/named'
-require 'active_record/base'
 
 module ActiveRecord
-  class SchemaMigration < ActiveRecord::Base
+  # This class is used to create a table that keeps track of which migrations
+  # have been applied to a given database. When a migration is run, its schema
+  # number is inserted in to the `SchemaMigration.table_name` so it doesn't need
+  # to be executed the next time.
+  class SchemaMigration < ActiveRecord::Base # :nodoc:
     class << self
       def primary_key
         nil
diff --git a/activerecord/lib/active_record/scoping.rb b/activerecord/lib/active_record/scoping.rb
index 3e43591672..e395970dc6 100644
--- a/activerecord/lib/active_record/scoping.rb
+++ b/activerecord/lib/active_record/scoping.rb
@@ -11,15 +11,26 @@ module ActiveRecord
 
     module ClassMethods
       def current_scope #:nodoc:
-        ScopeRegistry.value_for(:current_scope, base_class.to_s)
+        ScopeRegistry.value_for(:current_scope, self.to_s)
       end
 
       def current_scope=(scope) #:nodoc:
-        ScopeRegistry.set_value_for(:current_scope, base_class.to_s, scope)
+        ScopeRegistry.set_value_for(:current_scope, self.to_s, scope)
+      end
+
+      # Collects attributes from scopes that should be applied when creating
+      # an AR instance for the particular class this is called on.
+      def scope_attributes # :nodoc:
+        all.scope_for_create
+      end
+
+      # Are there attributes associated with this scope?
+      def scope_attributes? # :nodoc:
+        current_scope
       end
     end
 
-    def populate_with_current_scope_attributes
+    def populate_with_current_scope_attributes # :nodoc:
       return unless self.class.scope_attributes?
 
       self.class.scope_attributes.each do |att,value|
@@ -27,7 +38,7 @@ module ActiveRecord
       end
     end
 
-    def initialize_internals_callback
+    def initialize_internals_callback # :nodoc:
       super
       populate_with_current_scope_attributes
     end
@@ -48,8 +59,8 @@ module ActiveRecord
     #
     #   registry.value_for(:current_scope, "Board")
     #
-    # You will obtain whatever was defined in +some_new_scope+. The +value_for+
-    # and +set_value_for+ methods are delegated to the current +ScopeRegistry+
+    # You will obtain whatever was defined in +some_new_scope+. The #value_for
+    # and #set_value_for methods are delegated to the current ScopeRegistry
     # object, so the above example code can also be called as:
     #
     #   ActiveRecord::Scoping::ScopeRegistry.set_value_for(:current_scope,
diff --git a/activerecord/lib/active_record/scoping/default.rb b/activerecord/lib/active_record/scoping/default.rb
index 18190cb535..cdcb73382f 100644
--- a/activerecord/lib/active_record/scoping/default.rb
+++ b/activerecord/lib/active_record/scoping/default.rb
@@ -6,8 +6,10 @@ module ActiveRecord
       included do
         # Stores the default scope for the class.
         class_attribute :default_scopes, instance_writer: false, instance_predicate: false
+        class_attribute :default_scope_override, instance_predicate: false
 
         self.default_scopes = []
+        self.default_scope_override = nil
       end
 
       module ClassMethods
@@ -15,7 +17,7 @@ module ActiveRecord
         #
         #   class Post < ActiveRecord::Base
         #     def self.default_scope
-        #       where published: true
+        #       where(published: true)
         #     end
         #   end
         #
@@ -33,6 +35,11 @@ module ActiveRecord
           block_given? ? relation.scoping { yield } : relation
         end
 
+        # Are there attributes associated with this scope?
+        def scope_attributes? # :nodoc:
+          super || default_scopes.any? || respond_to?(:default_scope)
+        end
+
         def before_remove_const #:nodoc:
           self.current_scope = nil
         end
@@ -48,7 +55,7 @@ module ActiveRecord
         #
         #   Article.all # => SELECT * FROM articles WHERE published = true
         #
-        # The +default_scope+ is also applied while creating/building a record.
+        # The #default_scope is also applied while creating/building a record.
         # It is not applied while updating a record.
         #
         #   Article.new.published    # => true
@@ -58,7 +65,7 @@ module ActiveRecord
         # +default_scope+ macro, and it will be called when building the
         # default scope.)
         #
-        # If you use multiple +default_scope+ declarations in your model then
+        # If you use multiple #default_scope declarations in your model then
         # they will be merged together:
         #
         #   class Article < ActiveRecord::Base
@@ -69,7 +76,7 @@ module ActiveRecord
         #   Article.all # => SELECT * FROM articles WHERE published = true AND rating = 'G'
         #
         # This is also the case with inheritance and module includes where the
-        # parent or module defines a +default_scope+ and the child or including
+        # parent or module defines a #default_scope and the child or including
         # class defines a second one.
         #
         # If you need to do more complex things with a default scope, you can
@@ -94,11 +101,18 @@ module ActiveRecord
           self.default_scopes += [scope]
         end
 
-        def build_default_scope(base_rel = relation) # :nodoc:
-          if !Base.is_a?(method(:default_scope).owner)
+        def build_default_scope(base_rel = nil) # :nodoc:
+          return if abstract_class?
+
+          if self.default_scope_override.nil?
+            self.default_scope_override = !Base.is_a?(method(:default_scope).owner)
+          end
+
+          if self.default_scope_override
             # The user has defined their own default scope method, so call that
             evaluate_default_scope { default_scope }
           elsif default_scopes.any?
+            base_rel ||= relation
             evaluate_default_scope do
               default_scopes.inject(base_rel) do |default_scope, scope|
                 default_scope.merge(base_rel.scoping { scope.call })
diff --git a/activerecord/lib/active_record/scoping/named.rb b/activerecord/lib/active_record/scoping/named.rb
index 35420e6551..103569c84d 100644
--- a/activerecord/lib/active_record/scoping/named.rb
+++ b/activerecord/lib/active_record/scoping/named.rb
@@ -9,7 +9,7 @@ module ActiveRecord
       extend ActiveSupport::Concern
 
       module ClassMethods
-        # Returns an <tt>ActiveRecord::Relation</tt> scope object.
+        # Returns an ActiveRecord::Relation scope object.
         #
         #   posts = Post.all
         #   posts.size # Fires "select count(*) from  posts" and returns the count
@@ -20,7 +20,7 @@ module ActiveRecord
         #   fruits = fruits.limit(10) if limited?
         #
         # You can define a scope that applies to all finders using
-        # <tt>ActiveRecord::Base.default_scope</tt>.
+        # {default_scope}[rdoc-ref:Scoping::Default::ClassMethods#default_scope].
         def all
           if current_scope
             current_scope.clone
@@ -30,22 +30,22 @@ module ActiveRecord
         end
 
         def default_scoped # :nodoc:
-          relation.merge(build_default_scope)
-        end
-
-        # Collects attributes from scopes that should be applied when creating
-        # an AR instance for the particular class this is called on.
-        def scope_attributes # :nodoc:
-          all.scope_for_create
-        end
+          scope = build_default_scope
 
-        # Are there default attributes associated with this scope?
-        def scope_attributes? # :nodoc:
-          current_scope || default_scopes.any?
+          if scope
+            relation.spawn.merge!(scope)
+          else
+            relation
+          end
         end
 
-        # Adds a class method for retrieving and querying objects. A \scope
-        # represents a narrowing of a database query, such as
+        # Adds a class method for retrieving and querying objects.
+        # The method is intended to return an ActiveRecord::Relation
+        # object, which is composable with other scopes.
+        # If it returns nil or false, an
+        # {all}[rdoc-ref:Scoping::Named::ClassMethods#all] scope is returned instead.
+        #
+        # A \scope represents a narrowing of a database query, such as
         # <tt>where(color: :red).select('shirts.*').includes(:washing_instructions)</tt>.
         #
         #   class Shirt < ActiveRecord::Base
@@ -53,12 +53,12 @@ module ActiveRecord
         #     scope :dry_clean_only, -> { joins(:washing_instructions).where('washing_instructions.dry_clean_only = ?', true) }
         #   end
         #
-        # The above calls to +scope+ define class methods <tt>Shirt.red</tt> and
+        # The above calls to #scope define class methods <tt>Shirt.red</tt> and
         # <tt>Shirt.dry_clean_only</tt>. <tt>Shirt.red</tt>, in effect,
         # represents the query <tt>Shirt.where(color: 'red')</tt>.
         #
         # You should always pass a callable object to the scopes defined
-        # with +scope+. This ensures that the scope is re-evaluated each
+        # with #scope. This ensures that the scope is re-evaluated each
         # time it is called.
         #
         # Note that this is simply 'syntactic sugar' for defining an actual
@@ -71,14 +71,15 @@ module ActiveRecord
         #   end
         #
         # Unlike <tt>Shirt.find(...)</tt>, however, the object returned by
-        # <tt>Shirt.red</tt> is not an Array; it resembles the association object
-        # constructed by a +has_many+ declaration. For instance, you can invoke
-        # <tt>Shirt.red.first</tt>, <tt>Shirt.red.count</tt>,
+        # <tt>Shirt.red</tt> is not an Array but an ActiveRecord::Relation,
+        # which is composable with other scopes; it resembles the association object
+        # constructed by a {has_many}[rdoc-ref:Associations::ClassMethods#has_many]
+        # declaration. For instance, you can invoke <tt>Shirt.red.first</tt>, <tt>Shirt.red.count</tt>,
         # <tt>Shirt.red.where(size: 'small')</tt>. Also, just as with the
         # association objects, named \scopes act like an Array, implementing
         # Enumerable; <tt>Shirt.red.each(&block)</tt>, <tt>Shirt.red.first</tt>,
         # and <tt>Shirt.red.inject(memo, &block)</tt> all behave as if
-        # <tt>Shirt.red</tt> really was an Array.
+        # <tt>Shirt.red</tt> really was an array.
         #
         # These named \scopes are composable. For instance,
         # <tt>Shirt.red.dry_clean_only</tt> will produce all shirts that are
@@ -89,7 +90,8 @@ module ActiveRecord
         #
         # All scopes are available as class methods on the ActiveRecord::Base
         # descendant upon which the \scopes were defined. But they are also
-        # available to +has_many+ associations. If,
+        # available to {has_many}[rdoc-ref:Associations::ClassMethods#has_many]
+        # associations. If,
         #
         #   class Person < ActiveRecord::Base
         #     has_many :shirts
@@ -98,8 +100,8 @@ module ActiveRecord
         # then <tt>elton.shirts.red.dry_clean_only</tt> will return all of
         # Elton's red, dry clean only shirts.
         #
-        # \Named scopes can also have extensions, just as with +has_many+
-        # declarations:
+        # \Named scopes can also have extensions, just as with
+        # {has_many}[rdoc-ref:Associations::ClassMethods#has_many] declarations:
         #
         #   class Shirt < ActiveRecord::Base
         #     scope :red, -> { where(color: 'red') } do
@@ -151,11 +153,20 @@ module ActiveRecord
 
           extension = Module.new(&block) if block
 
-          singleton_class.send(:define_method, name) do |*args|
-            scope = all.scoping { body.call(*args) }
-            scope = scope.extending(extension) if extension
+          if body.respond_to?(:to_proc)
+            singleton_class.send(:define_method, name) do |*args|
+              scope = all.scoping { instance_exec(*args, &body) }
+              scope = scope.extending(extension) if extension
+
+              scope || all
+            end
+          else
+            singleton_class.send(:define_method, name) do |*args|
+              scope = all.scoping { body.call(*args) }
+              scope = scope.extending(extension) if extension
 
-            scope || all
+              scope || all
+            end
           end
         end
       end
diff --git a/activerecord/lib/active_record/secure_token.rb b/activerecord/lib/active_record/secure_token.rb
index 07031b6371..8abda2ac49 100644
--- a/activerecord/lib/active_record/secure_token.rb
+++ b/activerecord/lib/active_record/secure_token.rb
@@ -3,7 +3,7 @@ module ActiveRecord
     extend ActiveSupport::Concern
 
     module ClassMethods
-      # Example using has_secure_token
+      # Example using #has_secure_token
       #
       #   # Schema: User(token:string, auth_token:string)
       #   class User < ActiveRecord::Base
@@ -13,21 +13,21 @@ module ActiveRecord
       #
       #   user = User.new
       #   user.save
-      #   user.token # => "4kUgL2pdQMSCQtjE"
+      #   user.token # => "pX27zsMN2ViQKta1bGfLmVJE"
       #   user.auth_token # => "77TMHrHJFvFDwodq8w7Ev2m7"
       #   user.regenerate_token # => true
       #   user.regenerate_auth_token # => true
       #
-      # SecureRandom::base58 is used to generate the 24-character unique token, so collisions are highly unlikely.
+      # <tt>SecureRandom::base58</tt> is used to generate the 24-character unique token, so collisions are highly unlikely.
       #
       # Note that it's still possible to generate a race condition in the database in the same way that
-      # validates_presence_of can. You're encouraged to add a unique index in the database to deal with
-      # this even more unlikely scenario.
+      # {validates_uniqueness_of}[rdoc-ref:Validations::ClassMethods#validates_uniqueness_of] can.
+      # You're encouraged to add a unique index in the database to deal with this even more unlikely scenario.
       def has_secure_token(attribute = :token)
         # Load securerandom only when has_secure_token is used.
         require 'active_support/core_ext/securerandom'
         define_method("regenerate_#{attribute}") { update! attribute => self.class.generate_unique_secure_token }
-        before_create { self.send("#{attribute}=", self.class.generate_unique_secure_token) }
+        before_create { self.send("#{attribute}=", self.class.generate_unique_secure_token) unless self.send("#{attribute}?")}
       end
 
       def generate_unique_secure_token
@@ -36,4 +36,3 @@ module ActiveRecord
     end
   end
 end
-
diff --git a/activerecord/lib/active_record/serialization.rb b/activerecord/lib/active_record/serialization.rb
index 48c12dcf9f..5a408e7b8e 100644
--- a/activerecord/lib/active_record/serialization.rb
+++ b/activerecord/lib/active_record/serialization.rb
@@ -1,5 +1,5 @@
 module ActiveRecord #:nodoc:
-  # = Active Record Serialization
+  # = Active Record \Serialization
   module Serialization
     extend ActiveSupport::Concern
     include ActiveModel::Serializers::JSON
@@ -18,5 +18,3 @@ module ActiveRecord #:nodoc:
     end
   end
 end
-
-require 'active_record/serializers/xml_serializer'
diff --git a/activerecord/lib/active_record/serializers/xml_serializer.rb b/activerecord/lib/active_record/serializers/xml_serializer.rb
deleted file mode 100644
index c2484d02ed..0000000000
--- a/activerecord/lib/active_record/serializers/xml_serializer.rb
+++ /dev/null
@@ -1,193 +0,0 @@
-require 'active_support/core_ext/hash/conversions'
-
-module ActiveRecord #:nodoc:
-  module Serialization
-    include ActiveModel::Serializers::Xml
-
-    # Builds an XML document to represent the model. Some configuration is
-    # available through +options+. However more complicated cases should
-    # override ActiveRecord::Base#to_xml.
-    #
-    # By default the generated XML document will include the processing
-    # instruction and all the object's attributes. For example:
-    #
-    #   <?xml version="1.0" encoding="UTF-8"?>
-    #   <topic>
-    #     <title>The First Topic</title>
-    #     <author-name>David</author-name>
-    #     <id type="integer">1</id>
-    #     <approved type="boolean">false</approved>
-    #     <replies-count type="integer">0</replies-count>
-    #     <bonus-time type="dateTime">2000-01-01T08:28:00+12:00</bonus-time>
-    #     <written-on type="dateTime">2003-07-16T09:28:00+1200</written-on>
-    #     <content>Have a nice day</content>
-    #     <author-email-address>david@loudthinking.com</author-email-address>
-    #     <parent-id></parent-id>
-    #     <last-read type="date">2004-04-15</last-read>
-    #   </topic>
-    #
-    # This behavior can be controlled with <tt>:only</tt>, <tt>:except</tt>,
-    # <tt>:skip_instruct</tt>, <tt>:skip_types</tt>, <tt>:dasherize</tt> and <tt>:camelize</tt> .
-    # The <tt>:only</tt> and <tt>:except</tt> options are the same as for the
-    # +attributes+ method. The default is to dasherize all column names, but you
-    # can disable this setting <tt>:dasherize</tt> to +false+. Setting <tt>:camelize</tt>
-    # to +true+ will camelize all column names - this also overrides <tt>:dasherize</tt>.
-    # To not have the column type included in the XML output set <tt>:skip_types</tt> to +true+.
-    #
-    # For instance:
-    #
-    #   topic.to_xml(skip_instruct: true, except: [ :id, :bonus_time, :written_on, :replies_count ])
-    #
-    #   <topic>
-    #     <title>The First Topic</title>
-    #     <author-name>David</author-name>
-    #     <approved type="boolean">false</approved>
-    #     <content>Have a nice day</content>
-    #     <author-email-address>david@loudthinking.com</author-email-address>
-    #     <parent-id></parent-id>
-    #     <last-read type="date">2004-04-15</last-read>
-    #   </topic>
-    #
-    # To include first level associations use <tt>:include</tt>:
-    #
-    #   firm.to_xml include: [ :account, :clients ]
-    #
-    #   <?xml version="1.0" encoding="UTF-8"?>
-    #   <firm>
-    #     <id type="integer">1</id>
-    #     <rating type="integer">1</rating>
-    #     <name>37signals</name>
-    #     <clients type="array">
-    #       <client>
-    #         <rating type="integer">1</rating>
-    #         <name>Summit</name>
-    #       </client>
-    #       <client>
-    #         <rating type="integer">1</rating>
-    #         <name>Microsoft</name>
-    #       </client>
-    #     </clients>
-    #     <account>
-    #       <id type="integer">1</id>
-    #       <credit-limit type="integer">50</credit-limit>
-    #     </account>
-    #   </firm>
-    #
-    # Additionally, the record being serialized will be passed to a Proc's second
-    # parameter. This allows for ad hoc additions to the resultant document that
-    # incorporate the context of the record being serialized. And by leveraging the
-    # closure created by a Proc, to_xml can be used to add elements that normally fall
-    # outside of the scope of the model -- for example, generating and appending URLs
-    # associated with models.
-    #
-    #   proc = Proc.new { |options, record| options[:builder].tag!('name-reverse', record.name.reverse) }
-    #   firm.to_xml procs: [ proc ]
-    #
-    #   <firm>
-    #     # ... normal attributes as shown above ...
-    #     <name-reverse>slangis73</name-reverse>
-    #   </firm>
-    #
-    # To include deeper levels of associations pass a hash like this:
-    #
-    #   firm.to_xml include: {account: {}, clients: {include: :address}}
-    #   <?xml version="1.0" encoding="UTF-8"?>
-    #   <firm>
-    #     <id type="integer">1</id>
-    #     <rating type="integer">1</rating>
-    #     <name>37signals</name>
-    #     <clients type="array">
-    #       <client>
-    #         <rating type="integer">1</rating>
-    #         <name>Summit</name>
-    #         <address>
-    #           ...
-    #         </address>
-    #       </client>
-    #       <client>
-    #         <rating type="integer">1</rating>
-    #         <name>Microsoft</name>
-    #         <address>
-    #           ...
-    #         </address>
-    #       </client>
-    #     </clients>
-    #     <account>
-    #       <id type="integer">1</id>
-    #       <credit-limit type="integer">50</credit-limit>
-    #     </account>
-    #   </firm>
-    #
-    # To include any methods on the model being called use <tt>:methods</tt>:
-    #
-    #   firm.to_xml methods: [ :calculated_earnings, :real_earnings ]
-    #
-    #   <firm>
-    #     # ... normal attributes as shown above ...
-    #     <calculated-earnings>100000000000000000</calculated-earnings>
-    #     <real-earnings>5</real-earnings>
-    #   </firm>
-    #
-    # To call any additional Procs use <tt>:procs</tt>. The Procs are passed a
-    # modified version of the options hash that was given to +to_xml+:
-    #
-    #   proc = Proc.new { |options| options[:builder].tag!('abc', 'def') }
-    #   firm.to_xml procs: [ proc ]
-    #
-    #   <firm>
-    #     # ... normal attributes as shown above ...
-    #     <abc>def</abc>
-    #   </firm>
-    #
-    # Alternatively, you can yield the builder object as part of the +to_xml+ call:
-    #
-    #   firm.to_xml do |xml|
-    #     xml.creator do
-    #       xml.first_name "David"
-    #       xml.last_name "Heinemeier Hansson"
-    #     end
-    #   end
-    #
-    #   <firm>
-    #     # ... normal attributes as shown above ...
-    #     <creator>
-    #       <first_name>David</first_name>
-    #       <last_name>Heinemeier Hansson</last_name>
-    #     </creator>
-    #   </firm>
-    #
-    # As noted above, you may override +to_xml+ in your ActiveRecord::Base
-    # subclasses to have complete control about what's generated. The general
-    # form of doing this is:
-    #
-    #   class IHaveMyOwnXML < ActiveRecord::Base
-    #     def to_xml(options = {})
-    #       require 'builder'
-    #       options[:indent] ||= 2
-    #       xml = options[:builder] ||= ::Builder::XmlMarkup.new(indent: options[:indent])
-    #       xml.instruct! unless options[:skip_instruct]
-    #       xml.level_one do
-    #         xml.tag!(:second_level, 'content')
-    #       end
-    #     end
-    #   end
-    def to_xml(options = {}, &block)
-      XmlSerializer.new(self, options).serialize(&block)
-    end
-  end
-
-  class XmlSerializer < ActiveModel::Serializers::Xml::Serializer #:nodoc:
-    class Attribute < ActiveModel::Serializers::Xml::Serializer::Attribute #:nodoc:
-      def compute_type
-        klass = @serializable.class
-        column = klass.columns_hash[name] || Type::Value.new
-
-        type = ActiveSupport::XmlMini::TYPE_NAMES[value.class.name] || column.type
-
-        { :text => :string,
-          :time => :datetime }[type] || type
-      end
-      protected :compute_type
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/statement_cache.rb b/activerecord/lib/active_record/statement_cache.rb
index 3047a81ec4..f6b0efb88a 100644
--- a/activerecord/lib/active_record/statement_cache.rb
+++ b/activerecord/lib/active_record/statement_cache.rb
@@ -7,12 +7,14 @@ module ActiveRecord
   #     Book.where(name: "my book").where("author_id > 3")
   #   end
   #
-  # The cached statement is executed by using the +execute+ method:
+  # The cached statement is executed by using the
+  # [connection.execute]{rdoc-ref:ConnectionAdapters::DatabaseStatements#execute} method:
   #
   #   cache.execute([], Book, Book.connection)
   #
-  # The relation returned by the block is cached, and for each +execute+ call the cached relation gets duped.
-  # Database is queried when +to_a+ is called on the relation.
+  # The relation returned by the block is cached, and for each
+  # [execute]{rdoc-ref:ConnectionAdapters::DatabaseStatements#execute}
+  # call the cached relation gets duped. Database is queried when +to_a+ is called on the relation.
   #
   # If you want to cache the statement without the values you can use the +bind+ method of the
   # block parameter.
@@ -48,7 +50,7 @@ module ActiveRecord
       def sql_for(binds, connection)
         val = @values.dup
         binds = connection.prepare_binds_for_database(binds)
-        @indexes.each { |i| val[i] = connection.quote(binds.shift.last) }
+        @indexes.each { |i| val[i] = connection.quote(binds.shift) }
         val.join
       end
     end
@@ -67,21 +69,21 @@ module ActiveRecord
     end
 
     class BindMap # :nodoc:
-      def initialize(bind_values)
+      def initialize(bound_attributes)
         @indexes   = []
-        @bind_values = bind_values
+        @bound_attributes = bound_attributes
 
-        bind_values.each_with_index do |(_, value), i|
-          if Substitute === value
+        bound_attributes.each_with_index do |attr, i|
+          if Substitute === attr.value
             @indexes << i
           end
         end
       end
 
       def bind(values)
-        bvs = @bind_values.map(&:dup)
-        @indexes.each_with_index { |offset,i| bvs[offset][1] = values[i] }
-        bvs
+        bas = @bound_attributes.dup
+        @indexes.each_with_index { |offset,i| bas[offset] = bas[offset].with_cast_value(values[i]) }
+        bas
       end
     end
 
@@ -89,7 +91,7 @@ module ActiveRecord
 
     def self.create(connection, block = Proc.new)
       relation      = block.call Params.new
-      bind_map      = BindMap.new relation.bind_values
+      bind_map      = BindMap.new relation.bound_attributes
       query_builder = connection.cacheable_query relation.arel
       new query_builder, bind_map
     end
diff --git a/activerecord/lib/active_record/store.rb b/activerecord/lib/active_record/store.rb
index 919bc58ba5..1b407f7702 100644
--- a/activerecord/lib/active_record/store.rb
+++ b/activerecord/lib/active_record/store.rb
@@ -16,7 +16,8 @@ module ActiveRecord
   # JSON, YAML, Marshal are supported out of the box. Generally it can be any wrapper that provides +load+ and +dump+.
   #
   # NOTE: If you are using PostgreSQL specific columns like +hstore+ or +json+ there is no need for
-  # the serialization provided by +store+. Simply use +store_accessor+ instead to generate
+  # the serialization provided by {.store}[rdoc-ref:rdoc-ref:ClassMethods#store].
+  # Simply use {.store_accessor}[rdoc-ref:ClassMethods#store_accessor] instead to generate
   # the accessor methods. Be aware that these columns use a string keyed hash and do not allow access
   # using a symbol.
   #
@@ -43,7 +44,7 @@ module ActiveRecord
   #     store_accessor :settings, :privileges, :servants
   #   end
   #
-  # The stored attribute names can be retrieved using +stored_attributes+.
+  # The stored attribute names can be retrieved using {.stored_attributes}[rdoc-ref:rdoc-ref:ClassMethods#stored_attributes].
   #
   #   User.stored_attributes[:settings] # [:color, :homepage]
   #
diff --git a/activerecord/lib/active_record/suppressor.rb b/activerecord/lib/active_record/suppressor.rb
new file mode 100644
index 0000000000..b3644bf569
--- /dev/null
+++ b/activerecord/lib/active_record/suppressor.rb
@@ -0,0 +1,54 @@
+module ActiveRecord
+  # ActiveRecord::Suppressor prevents the receiver from being saved during
+  # a given block.
+  #
+  # For example, here's a pattern of creating notifications when new comments
+  # are posted. (The notification may in turn trigger an email, a push
+  # notification, or just appear in the UI somewhere):
+  #
+  #   class Comment < ActiveRecord::Base
+  #     belongs_to :commentable, polymorphic: true
+  #     after_create -> { Notification.create! comment: self,
+  #       recipients: commentable.recipients }
+  #   end
+  #
+  # That's what you want the bulk of the time. New comment creates a new
+  # Notification. But there may well be off cases, like copying a commentable
+  # and its comments, where you don't want that. So you'd have a concern
+  # something like this:
+  #
+  #   module Copyable
+  #     def copy_to(destination)
+  #       Notification.suppress do
+  #         # Copy logic that creates new comments that we do not want
+  #         # triggering notifications.
+  #       end
+  #     end
+  #   end
+  module Suppressor
+    extend ActiveSupport::Concern
+
+    module ClassMethods
+      def suppress(&block)
+        SuppressorRegistry.suppressed[name] = true
+        yield
+      ensure
+        SuppressorRegistry.suppressed[name] = false
+      end
+    end
+
+    def create_or_update(*args) # :nodoc:
+      SuppressorRegistry.suppressed[self.class.name] ? true : super
+    end
+  end
+
+  class SuppressorRegistry # :nodoc:
+    extend ActiveSupport::PerThreadRegistry
+
+    attr_reader :suppressed
+
+    def initialize
+      @suppressed = {}
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/table_metadata.rb b/activerecord/lib/active_record/table_metadata.rb
index 11e33e8dfe..f9bb1cf5e0 100644
--- a/activerecord/lib/active_record/table_metadata.rb
+++ b/activerecord/lib/active_record/table_metadata.rb
@@ -1,6 +1,7 @@
 module ActiveRecord
   class TableMetadata # :nodoc:
     delegate :foreign_type, :foreign_key, to: :association, prefix: true
+    delegate :association_primary_key, to: :association
 
     def initialize(klass, arel_table, association = nil)
       @klass = klass
@@ -9,19 +10,29 @@ module ActiveRecord
     end
 
     def resolve_column_aliases(hash)
-      hash = hash.dup
-      hash.keys.grep(Symbol) do |key|
-        if klass.attribute_alias? key
-          hash[klass.attribute_alias(key)] = hash.delete key
+      # This method is a hot spot, so for now, use Hash[] to dup the hash.
+      #   https://bugs.ruby-lang.org/issues/7166
+      new_hash = Hash[hash]
+      hash.each do |key, _|
+        if (key.is_a?(Symbol)) && klass.attribute_alias?(key)
+          new_hash[klass.attribute_alias(key)] = new_hash.delete(key)
         end
       end
-      hash
+      new_hash
     end
 
     def arel_attribute(column_name)
       arel_table[column_name]
     end
 
+    def type(column_name)
+      if klass
+        klass.type_for_attribute(column_name.to_s)
+      else
+        Type::Value.new
+      end
+    end
+
     def associated_with?(association_name)
       klass && klass._reflect_on_association(association_name)
     end
@@ -32,9 +43,9 @@ module ActiveRecord
       association = klass._reflect_on_association(table_name)
       if association && !association.polymorphic?
         association_klass = association.klass
-        arel_table = association_klass.arel_table
+        arel_table = association_klass.arel_table.alias(table_name)
       else
-        type_caster = TypeCaster::Connection.new(klass.connection, table_name)
+        type_caster = TypeCaster::Connection.new(klass, table_name)
         association_klass = nil
         arel_table = Arel::Table.new(table_name, type_caster: type_caster)
       end
diff --git a/activerecord/lib/active_record/tasks/database_tasks.rb b/activerecord/lib/active_record/tasks/database_tasks.rb
index 69aceb66b1..c0c29a618c 100644
--- a/activerecord/lib/active_record/tasks/database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/database_tasks.rb
@@ -5,7 +5,7 @@ module ActiveRecord
     class DatabaseAlreadyExists < StandardError; end # :nodoc:
     class DatabaseNotSupported < StandardError; end # :nodoc:
 
-    # <tt>ActiveRecord::Tasks::DatabaseTasks</tt> is a utility class, which encapsulates
+    # ActiveRecord::Tasks::DatabaseTasks is a utility class, which encapsulates
     # logic behind common tasks used to manage database and migrations.
     #
     # The tasks defined here are used with Rake tasks provided by Active Record.
@@ -18,15 +18,15 @@ module ActiveRecord
     #
     # The possible config values are:
     #
-    #   * +env+: current environment (like Rails.env).
-    #   * +database_configuration+: configuration of your databases (as in +config/database.yml+).
-    #   * +db_dir+: your +db+ directory.
-    #   * +fixtures_path+: a path to fixtures directory.
-    #   * +migrations_paths+: a list of paths to directories with migrations.
-    #   * +seed_loader+: an object which will load seeds, it needs to respond to the +load_seed+ method.
-    #   * +root+: a path to the root of the application.
+    # * +env+: current environment (like Rails.env).
+    # * +database_configuration+: configuration of your databases (as in +config/database.yml+).
+    # * +db_dir+: your +db+ directory.
+    # * +fixtures_path+: a path to fixtures directory.
+    # * +migrations_paths+: a list of paths to directories with migrations.
+    # * +seed_loader+: an object which will load seeds, it needs to respond to the +load_seed+ method.
+    # * +root+: a path to the root of the application.
     #
-    # Example usage of +DatabaseTasks+ outside Rails could look as such:
+    # Example usage of DatabaseTasks outside Rails could look as such:
     #
     #   include ActiveRecord::Tasks
     #   DatabaseTasks.database_configuration = YAML.load_file('my_database_config.yml')
@@ -94,8 +94,9 @@ module ActiveRecord
       rescue DatabaseAlreadyExists
         $stderr.puts "#{configuration['database']} already exists"
       rescue Exception => error
-        $stderr.puts error, *(error.backtrace)
+        $stderr.puts error
         $stderr.puts "Couldn't create database for #{configuration.inspect}"
+        raise
       end
 
       def create_all
@@ -115,8 +116,9 @@ module ActiveRecord
       rescue ActiveRecord::NoDatabaseError
         $stderr.puts "Database '#{configuration['database']}' does not exist"
       rescue Exception => error
-        $stderr.puts error, *(error.backtrace)
+        $stderr.puts error
         $stderr.puts "Couldn't drop #{configuration['database']}"
+        raise
       end
 
       def drop_all
@@ -134,7 +136,7 @@ module ActiveRecord
         version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
         scope   = ENV['SCOPE']
         verbose_was, Migration.verbose = Migration.verbose, verbose
-        Migrator.migrate(Migrator.migrations_paths, version) do |migration|
+        Migrator.migrate(migrations_paths, version) do |migration|
           scope.blank? || scope == migration.scope
         end
       ensure
@@ -212,7 +214,7 @@ module ActiveRecord
         load_schema(*args)
       end
 
-      def schema_file(format = ActiveSupport::Base.schema_format)
+      def schema_file(format = ActiveRecord::Base.schema_format)
         case format
         when :ruby
           File.join(db_dir, "schema.rb")
@@ -221,12 +223,6 @@ module ActiveRecord
         end
       end
 
-      def load_schema_current_if_exists(format = ActiveRecord::Base.schema_format, file = nil, environment = env)
-        if File.exist?(file || schema_file(format))
-          load_schema_current(format, file, environment)
-        end
-      end
-
       def load_schema_current(format = ActiveRecord::Base.schema_format, file = nil, environment = env)
         each_current_configuration(environment) { |configuration|
           load_schema configuration, format, file
diff --git a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
index eafbb2c249..8929aa85c8 100644
--- a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
@@ -23,7 +23,7 @@ module ActiveRecord
         end
       rescue error_class => error
         if error.respond_to?(:errno) && error.errno == ACCESS_DENIED_ERROR
-          $stdout.print error.error
+          $stdout.print error.message
           establish_connection root_configuration_without_database
           connection.create_database configuration['database'], creation_options
           if configuration['username'] != 'root'
@@ -56,21 +56,21 @@ module ActiveRecord
       end
 
       def structure_dump(filename)
-        args = prepare_command_options('mysqldump')
+        args = prepare_command_options
         args.concat(["--result-file", "#{filename}"])
         args.concat(["--no-data"])
+        args.concat(["--routines"])
         args.concat(["#{configuration['database']}"])
-        unless Kernel.system(*args)
-          $stderr.puts "Could not dump the database structure. "\
-                       "Make sure `mysqldump` is in your PATH and check the command output for warnings."
-        end
+
+        run_cmd('mysqldump', args, 'dumping')
       end
 
       def structure_load(filename)
-        args = prepare_command_options('mysql')
+        args = prepare_command_options
         args.concat(['--execute', %{SET FOREIGN_KEY_CHECKS = 0; SOURCE #{filename}; SET FOREIGN_KEY_CHECKS = 1}])
         args.concat(["--database", "#{configuration['database']}"])
-        Kernel.system(*args)
+
+        run_cmd('mysql', args, 'loading')
       end
 
       private
@@ -129,17 +129,33 @@ IDENTIFIED BY '#{configuration['password']}' WITH GRANT OPTION;
         $stdin.gets.strip
       end
 
-      def prepare_command_options(command)
-        args = [command]
-        args.concat(['--user', configuration['username']]) if configuration['username']
-        args << "--password=#{configuration['password']}"  if configuration['password']
-        args.concat(['--default-character-set', configuration['encoding']]) if configuration['encoding']
-        configuration.slice('host', 'port', 'socket').each do |k, v|
-          args.concat([ "--#{k}", v.to_s ]) if v
-        end
+      def prepare_command_options
+        args = {
+          'host'      => '--host',
+          'port'      => '--port',
+          'socket'    => '--socket',
+          'username'  => '--user',
+          'password'  => '--password',
+          'encoding'  => '--default-character-set',
+          'sslca'     => '--ssl-ca',
+          'sslcert'   => '--ssl-cert',
+          'sslcapath' => '--ssl-capath',
+          'sslcipher' => '--ssh-cipher',
+          'sslkey'    => '--ssl-key'
+        }.map { |opt, arg| "#{arg}=#{configuration[opt]}" if configuration[opt] }.compact
 
         args
       end
+
+      def run_cmd(cmd, args, action)
+        fail run_cmd_error(cmd, args, action) unless Kernel.system(cmd, *args)
+      end
+
+      def run_cmd_error(cmd, args, action)
+        msg = "failed to execute: `#{cmd}`\n"
+        msg << "Please check the output above for any errors and make sure that `#{cmd}` is installed in your PATH and has proper permissions.\n\n"
+        msg
+      end
     end
   end
 end
diff --git a/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb b/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
index ce1de4b76e..cd7d949239 100644
--- a/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
@@ -1,5 +1,3 @@
-require 'shellwords'
-
 module ActiveRecord
   module Tasks # :nodoc:
     class PostgreSQLDatabaseTasks # :nodoc:
@@ -46,20 +44,31 @@ module ActiveRecord
 
       def structure_dump(filename)
         set_psql_env
-        search_path = configuration['schema_search_path']
-        unless search_path.blank?
-          search_path = search_path.split(",").map{|search_path_part| "--schema=#{Shellwords.escape(search_path_part.strip)}" }.join(" ")
-        end
 
-        command = "pg_dump -i -s -x -O -f #{Shellwords.escape(filename)} #{search_path} #{Shellwords.escape(configuration['database'])}"
-        raise 'Error dumping database' unless Kernel.system(command)
+        search_path = case ActiveRecord::Base.dump_schemas
+        when :schema_search_path
+          configuration['schema_search_path']
+        when :all
+          nil
+        when String
+          ActiveRecord::Base.dump_schemas
+        end
 
+        args = ['-s', '-x', '-O', '-f', filename]
+        unless search_path.blank?
+          args << search_path.split(',').map do |part|
+            "--schema=#{part.strip}"
+          end.join(' ')
+        end
+        args << configuration['database']
+        run_cmd('pg_dump', args, 'dumping')
         File.open(filename, "a") { |f| f << "SET search_path TO #{connection.schema_search_path};\n\n" }
       end
 
       def structure_load(filename)
         set_psql_env
-        Kernel.system("psql -q -f #{Shellwords.escape(filename)} #{configuration['database']}")
+        args = [ '-q', '-f', filename, configuration['database'] ]
+        run_cmd('psql', args, 'loading' )
       end
 
       private
@@ -85,6 +94,17 @@ module ActiveRecord
         ENV['PGPASSWORD'] = configuration['password'].to_s if configuration['password']
         ENV['PGUSER']     = configuration['username'].to_s if configuration['username']
       end
+
+      def run_cmd(cmd, args, action)
+        fail run_cmd_error(cmd, args, action) unless Kernel.system(cmd, *args)
+      end
+
+      def run_cmd_error(cmd, args, action)
+        msg = "failed to execute:\n"
+        msg << "#{cmd} #{args.join(' ')}\n\n"
+        msg << "Please check the output above for any errors and make sure that `#{cmd}` is installed in your PATH and has proper permissions.\n\n"
+        msg
+      end
     end
   end
 end
diff --git a/activerecord/lib/active_record/tasks/sqlite_database_tasks.rb b/activerecord/lib/active_record/tasks/sqlite_database_tasks.rb
index 9ab64d0325..9ec3c8a94a 100644
--- a/activerecord/lib/active_record/tasks/sqlite_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/sqlite_database_tasks.rb
@@ -19,11 +19,15 @@ module ActiveRecord
         path = Pathname.new configuration['database']
         file = path.absolute? ? path.to_s : File.join(root, path)
 
-        FileUtils.rm(file) if File.exist?(file)
+        FileUtils.rm(file)
+      rescue Errno::ENOENT => error
+        raise NoDatabaseError.new(error.message, error)
       end
 
       def purge
         drop
+      rescue NoDatabaseError
+      ensure
         create
       end
 
diff --git a/activerecord/lib/active_record/timestamp.rb b/activerecord/lib/active_record/timestamp.rb
index 20e4235788..a572c109d8 100644
--- a/activerecord/lib/active_record/timestamp.rb
+++ b/activerecord/lib/active_record/timestamp.rb
@@ -1,5 +1,5 @@
 module ActiveRecord
-  # = Active Record Timestamp
+  # = Active Record \Timestamp
   #
   # Active Record automatically timestamps create and update operations if the
   # table has fields named <tt>created_at/created_on</tt> or
@@ -15,14 +15,21 @@ module ActiveRecord
   #
   # == Time Zone aware attributes
   #
-  # By default, ActiveRecord::Base keeps all the datetime columns time zone aware by executing following code.
+  # Active Record keeps all the <tt>datetime</tt> and <tt>time</tt> columns
+  # time-zone aware. By default, these values are stored in the database as UTC
+  # and converted back to the current <tt>Time.zone</tt> when pulled from the database.
   #
-  #   config.active_record.time_zone_aware_attributes = true
+  # This feature can be turned off completely by setting:
   #
-  # This feature can easily be turned off by assigning value <tt>false</tt> .
+  #   config.active_record.time_zone_aware_attributes = false
   #
-  # If your attributes are time zone aware and you desire to skip time zone conversion to the current Time.zone
-  # when reading certain attributes then you can do following:
+  # You can also specify that only <tt>datetime</tt> columns should be time-zone
+  # aware (while <tt>time</tt> should not) by setting:
+  #
+  #   ActiveRecord::Base.time_zone_aware_types = [:datetime]
+  #
+  # Finally, you can indicate specific attributes of a model for which time zone
+  # conversion should not applied, for instance by setting:
   #
   #   class Topic < ActiveRecord::Base
   #     self.skip_time_zone_conversion_for_attributes = [:written_on]
diff --git a/activerecord/lib/active_record/touch_later.rb b/activerecord/lib/active_record/touch_later.rb
new file mode 100644
index 0000000000..4352a0ffea
--- /dev/null
+++ b/activerecord/lib/active_record/touch_later.rb
@@ -0,0 +1,50 @@
+module ActiveRecord
+  # = Active Record Touch Later
+  module TouchLater
+    extend ActiveSupport::Concern
+
+    included do
+      before_commit_without_transaction_enrollment :touch_deferred_attributes
+    end
+
+    def touch_later(*names) # :nodoc:
+      raise ActiveRecordError, "cannot touch on a new record object" unless persisted?
+
+      @_defer_touch_attrs ||= timestamp_attributes_for_update_in_model
+      @_defer_touch_attrs |= names
+      @_touch_time = current_time_from_proper_timezone
+
+      surreptitiously_touch @_defer_touch_attrs
+      self.class.connection.add_transaction_record self
+    end
+
+    def touch(*names, time: nil) # :nodoc:
+      if has_defer_touch_attrs?
+        names |= @_defer_touch_attrs
+      end
+      super(*names, time: time)
+    end
+
+    private
+      def surreptitiously_touch(attrs)
+        attrs.each { |attr| write_attribute attr, @_touch_time }
+        clear_attribute_changes attrs
+      end
+
+      def touch_deferred_attributes
+        if has_defer_touch_attrs? && persisted?
+          @_touching_delayed_records = true
+          touch(*@_defer_touch_attrs, time: @_touch_time)
+          @_touching_delayed_records, @_defer_touch_attrs, @_touch_time = nil, nil, nil
+        end
+      end
+
+      def has_defer_touch_attrs?
+        defined?(@_defer_touch_attrs) && @_defer_touch_attrs.present?
+      end
+
+      def touching_delayed_records?
+        defined?(@_touching_delayed_records) && @_touching_delayed_records
+      end
+  end
+end
diff --git a/activerecord/lib/active_record/transactions.rb b/activerecord/lib/active_record/transactions.rb
index 0fd2862b2c..8de82feae3 100644
--- a/activerecord/lib/active_record/transactions.rb
+++ b/activerecord/lib/active_record/transactions.rb
@@ -7,15 +7,20 @@ module ActiveRecord
 
     included do
       define_callbacks :commit, :rollback,
+                       :before_commit,
+                       :before_commit_without_transaction_enrollment,
+                       :commit_without_transaction_enrollment,
+                       :rollback_without_transaction_enrollment,
+                       terminator: deprecated_false_terminator,
                        scope: [:kind, :name]
     end
 
     # = Active Record Transactions
     #
-    # Transactions are protective blocks where SQL statements are only permanent
+    # \Transactions are protective blocks where SQL statements are only permanent
     # if they can all succeed as one atomic action. The classic example is a
     # transfer between two accounts where you can only have a deposit if the
-    # withdrawal succeeded and vice versa. Transactions enforce the integrity of
+    # withdrawal succeeded and vice versa. \Transactions enforce the integrity of
     # the database and guard the data against program errors or database
     # break-downs. So basically you should use transaction blocks whenever you
     # have a number of statements that must be executed together or not at all.
@@ -35,20 +40,20 @@ module ActiveRecord
     #
     # == Different Active Record classes in a single transaction
     #
-    # Though the transaction class method is called on some Active Record class,
+    # Though the #transaction class method is called on some Active Record class,
     # the objects within the transaction block need not all be instances of
     # that class. This is because transactions are per-database connection, not
     # per-model.
     #
     # In this example a +balance+ record is transactionally saved even
-    # though +transaction+ is called on the +Account+ class:
+    # though #transaction is called on the +Account+ class:
     #
     #   Account.transaction do
     #     balance.save!
     #     account.save!
     #   end
     #
-    # The +transaction+ method is also available as a model instance method.
+    # The #transaction method is also available as a model instance method.
     # For example, you can also do this:
     #
     #   balance.transaction do
@@ -75,7 +80,8 @@ module ActiveRecord
     #
     # == +save+ and +destroy+ are automatically wrapped in a transaction
     #
-    # Both +save+ and +destroy+ come wrapped in a transaction that ensures
+    # Both {#save}[rdoc-ref:Persistence#save] and
+    # {#destroy}[rdoc-ref:Persistence#destroy] come wrapped in a transaction that ensures
     # that whatever you do in validations or callbacks will happen under its
     # protected cover. So you can use validations to check for values that
     # the transaction depends on or you can raise exceptions in the callbacks
@@ -84,7 +90,7 @@ module ActiveRecord
     # As a consequence changes to the database are not seen outside your connection
     # until the operation is complete. For example, if you try to update the index
     # of a search engine in +after_save+ the indexer won't see the updated record.
-    # The +after_commit+ callback is the only one that is triggered once the update
+    # The #after_commit callback is the only one that is triggered once the update
     # is committed. See below.
     #
     # == Exception handling and rolling back
@@ -93,11 +99,11 @@ module ActiveRecord
     # be propagated (after triggering the ROLLBACK), so you should be ready to
     # catch those in your application code.
     #
-    # One exception is the <tt>ActiveRecord::Rollback</tt> exception, which will trigger
+    # One exception is the ActiveRecord::Rollback exception, which will trigger
     # a ROLLBACK when raised, but not be re-raised by the transaction block.
     #
-    # *Warning*: one should not catch <tt>ActiveRecord::StatementInvalid</tt> exceptions
-    # inside a transaction block. <tt>ActiveRecord::StatementInvalid</tt> exceptions indicate that an
+    # *Warning*: one should not catch ActiveRecord::StatementInvalid exceptions
+    # inside a transaction block. ActiveRecord::StatementInvalid exceptions indicate that an
     # error occurred at the database level, for example when a unique constraint
     # is violated. On some database systems, such as PostgreSQL, database errors
     # inside a transaction cause the entire transaction to become unusable
@@ -123,11 +129,11 @@ module ActiveRecord
     #   end
     #
     # One should restart the entire transaction if an
-    # <tt>ActiveRecord::StatementInvalid</tt> occurred.
+    # ActiveRecord::StatementInvalid occurred.
     #
     # == Nested transactions
     #
-    # +transaction+ calls can be nested. By default, this makes all database
+    # #transaction calls can be nested. By default, this makes all database
     # statements in the nested transaction block become part of the parent
     # transaction. For example, the following behavior may be surprising:
     #
@@ -139,7 +145,7 @@ module ActiveRecord
     #     end
     #   end
     #
-    # creates both "Kotori" and "Nemu". Reason is the <tt>ActiveRecord::Rollback</tt>
+    # creates both "Kotori" and "Nemu". Reason is the ActiveRecord::Rollback
     # exception in the nested block does not issue a ROLLBACK. Since these exceptions
     # are captured in transaction blocks, the parent block does not see it and the
     # real transaction is committed.
@@ -163,22 +169,22 @@ module ActiveRecord
     # writing, the only database that we're aware of that supports true nested
     # transactions, is MS-SQL. Because of this, Active Record emulates nested
     # transactions by using savepoints on MySQL and PostgreSQL. See
-    # http://dev.mysql.com/doc/refman/5.6/en/savepoint.html
+    # http://dev.mysql.com/doc/refman/5.7/en/savepoint.html
     # for more information about savepoints.
     #
-    # === Callbacks
+    # === \Callbacks
     #
     # There are two types of callbacks associated with committing and rolling back transactions:
-    # +after_commit+ and +after_rollback+.
+    # #after_commit and #after_rollback.
     #
-    # +after_commit+ callbacks are called on every record saved or destroyed within a
-    # transaction immediately after the transaction is committed. +after_rollback+ callbacks
+    # #after_commit callbacks are called on every record saved or destroyed within a
+    # transaction immediately after the transaction is committed. #after_rollback callbacks
     # are called on every record saved or destroyed within a transaction immediately after the
     # transaction or savepoint is rolled back.
     #
     # These callbacks are useful for interacting with other systems since you will be guaranteed
     # that the callback is only executed when the database is in a permanent state. For example,
-    # +after_commit+ is a good spot to put in a hook to clearing a cache since clearing it from
+    # #after_commit is a good spot to put in a hook to clearing a cache since clearing it from
     # within a transaction could trigger the cache to be regenerated before the database is updated.
     #
     # === Caveats
@@ -192,20 +198,24 @@ module ActiveRecord
     # automatically released. The following example demonstrates the problem:
     #
     #   Model.connection.transaction do                           # BEGIN
-    #     Model.connection.transaction(requires_new: true) do  # CREATE SAVEPOINT active_record_1
+    #     Model.connection.transaction(requires_new: true) do     # CREATE SAVEPOINT active_record_1
     #       Model.connection.create_table(...)                    # active_record_1 now automatically released
-    #     end                                                     # RELEASE savepoint active_record_1
+    #     end                                                     # RELEASE SAVEPOINT active_record_1
     #                                                             # ^^^^ BOOM! database error!
     #   end
     #
     # Note that "TRUNCATE" is also a MySQL DDL statement!
     module ClassMethods
-      # See ActiveRecord::Transactions::ClassMethods for detailed documentation.
+      # See the ConnectionAdapters::DatabaseStatements#transaction API docs.
       def transaction(options = {}, &block)
-        # See the ConnectionAdapters::DatabaseStatements#transaction API docs.
         connection.transaction(options, &block)
       end
 
+      def before_commit(*args, &block) # :nodoc:
+        set_options_for_callbacks!(args)
+        set_callback(:before_commit, :before, *args, &block)
+      end
+
       # This callback is called after a record has been created, updated, or destroyed.
       #
       # You can specify that the callback should only be fired by a certain action with
@@ -218,8 +228,6 @@ module ActiveRecord
       #   after_commit :do_foo_bar, on: [:create, :update]
       #   after_commit :do_bar_baz, on: [:update, :destroy]
       #
-      # Note that transactional fixtures do not play well with this feature. Please
-      # use the +test_after_commit+ gem to have these hooks fired in tests.
       def after_commit(*args, &block)
         set_options_for_callbacks!(args)
         set_callback(:commit, :after, *args, &block)
@@ -227,12 +235,27 @@ module ActiveRecord
 
       # This callback is called after a create, update, or destroy are rolled back.
       #
-      # Please check the documentation of +after_commit+ for options.
+      # Please check the documentation of #after_commit for options.
       def after_rollback(*args, &block)
         set_options_for_callbacks!(args)
         set_callback(:rollback, :after, *args, &block)
       end
 
+      def before_commit_without_transaction_enrollment(*args, &block) # :nodoc:
+        set_options_for_callbacks!(args)
+        set_callback(:before_commit_without_transaction_enrollment, :before, *args, &block)
+      end
+
+      def after_commit_without_transaction_enrollment(*args, &block) # :nodoc:
+        set_options_for_callbacks!(args)
+        set_callback(:commit_without_transaction_enrollment, :after, *args, &block)
+      end
+
+      def after_rollback_without_transaction_enrollment(*args, &block) # :nodoc:
+        set_options_for_callbacks!(args)
+        set_callback(:rollback_without_transaction_enrollment, :after, *args, &block)
+      end
+
       def raise_in_transactional_callbacks
         ActiveSupport::Deprecation.warn('ActiveRecord::Base.raise_in_transactional_callbacks is deprecated and will be removed without replacement.')
         true
@@ -296,31 +319,46 @@ module ActiveRecord
       clear_transaction_record_state
     end
 
-    # Call the +after_commit+ callbacks.
+    def before_committed! # :nodoc:
+      _run_before_commit_without_transaction_enrollment_callbacks
+      _run_before_commit_callbacks
+    end
+
+    # Call the #after_commit callbacks.
     #
     # Ensure that it is not called if the object was never persisted (failed create),
     # but call it after the commit of a destroyed object.
     def committed!(should_run_callbacks: true) #:nodoc:
-      _run_commit_callbacks if should_run_callbacks && destroyed? || persisted?
+      if should_run_callbacks && destroyed? || persisted?
+        _run_commit_without_transaction_enrollment_callbacks
+        _run_commit_callbacks
+      end
     ensure
       force_clear_transaction_record_state
     end
 
-    # Call the +after_rollback+ callbacks. The +force_restore_state+ argument indicates if the record
+    # Call the #after_rollback callbacks. The +force_restore_state+ argument indicates if the record
     # state should be rolled back to the beginning or just to the last savepoint.
     def rolledback!(force_restore_state: false, should_run_callbacks: true) #:nodoc:
-      _run_rollback_callbacks if should_run_callbacks
+      if should_run_callbacks
+        _run_rollback_callbacks
+        _run_rollback_without_transaction_enrollment_callbacks
+      end
     ensure
       restore_transaction_record_state(force_restore_state)
       clear_transaction_record_state
     end
 
-    # Add the record to the current transaction so that the +after_rollback+ and +after_commit+ callbacks
+    # Add the record to the current transaction so that the #after_rollback and #after_commit callbacks
     # can be called.
     def add_to_transaction
-      if self.class.connection.add_transaction_record(self)
-        remember_transaction_record_state
+      if has_transactional_callbacks?
+        self.class.connection.add_transaction_record(self)
+      else
+        sync_with_transaction_state
+        set_transaction_state(self.class.connection.transaction_state)
       end
+      remember_transaction_record_state
     end
 
     # Executes +method+ within a transaction and captures its return value as a
@@ -343,6 +381,10 @@ module ActiveRecord
         raise ActiveRecord::Rollback unless status
       end
       status
+    ensure
+      if @transaction_state && @transaction_state.committed?
+        clear_transaction_record_state
+      end
     end
 
     protected
@@ -375,10 +417,14 @@ module ActiveRecord
         transaction_level = (@_start_transaction_state[:level] || 0) - 1
         if transaction_level < 1 || force
           restore_state = @_start_transaction_state
-          thaw unless restore_state[:frozen?]
+          thaw
           @new_record = restore_state[:new_record]
           @destroyed  = restore_state[:destroyed]
-          write_attribute(self.class.primary_key, restore_state[:id]) if self.class.primary_key
+          pk = self.class.primary_key
+          if pk && read_attribute(pk) != restore_state[:id]
+            write_attribute(pk, restore_state[:id])
+          end
+          freeze if restore_state[:frozen?]
         end
       end
     end
@@ -401,5 +447,43 @@ module ActiveRecord
         end
       end
     end
+
+    private
+
+    def set_transaction_state(state) # :nodoc:
+      @transaction_state = state
+    end
+
+    def has_transactional_callbacks? # :nodoc:
+      !_rollback_callbacks.empty? || !_commit_callbacks.empty? || !_before_commit_callbacks.empty?
+    end
+
+    # Updates the attributes on this particular Active Record object so that
+    # if it's associated with a transaction, then the state of the Active Record
+    # object will be updated to reflect the current state of the transaction
+    #
+    # The +@transaction_state+ variable stores the states of the associated
+    # transaction. This relies on the fact that a transaction can only be in
+    # one rollback or commit (otherwise a list of states would be required)
+    # Each Active Record object inside of a transaction carries that transaction's
+    # TransactionState.
+    #
+    # This method checks to see if the ActiveRecord object's state reflects
+    # the TransactionState, and rolls back or commits the Active Record object
+    # as appropriate.
+    #
+    # Since Active Record objects can be inside multiple transactions, this
+    # method recursively goes through the parent of the TransactionState and
+    # checks if the Active Record object reflects the state of the object.
+    def sync_with_transaction_state
+      update_attributes_from_transaction_state(@transaction_state)
+    end
+
+    def update_attributes_from_transaction_state(transaction_state)
+      if transaction_state && transaction_state.finalized?
+        restore_transaction_record_state if transaction_state.rolledback?
+        clear_transaction_record_state
+      end
+    end
   end
 end
diff --git a/activerecord/lib/active_record/type.rb b/activerecord/lib/active_record/type.rb
index 250e8d5b23..e210e94f00 100644
--- a/activerecord/lib/active_record/type.rb
+++ b/activerecord/lib/active_record/type.rb
@@ -1,23 +1,72 @@
-require 'active_record/type/decorator'
-require 'active_record/type/mutable'
-require 'active_record/type/numeric'
-require 'active_record/type/time_value'
-require 'active_record/type/value'
-
-require 'active_record/type/big_integer'
-require 'active_record/type/binary'
-require 'active_record/type/boolean'
+require 'active_model/type'
+
+require 'active_record/type/internal/abstract_json'
+require 'active_record/type/internal/timezone'
+
 require 'active_record/type/date'
 require 'active_record/type/date_time'
-require 'active_record/type/decimal'
-require 'active_record/type/decimal_without_scale'
-require 'active_record/type/float'
-require 'active_record/type/integer'
-require 'active_record/type/serialized'
-require 'active_record/type/string'
-require 'active_record/type/text'
 require 'active_record/type/time'
-require 'active_record/type/unsigned_integer'
+
+require 'active_record/type/serialized'
+require 'active_record/type/adapter_specific_registry'
 
 require 'active_record/type/type_map'
 require 'active_record/type/hash_lookup_type_map'
+
+module ActiveRecord
+  module Type
+    @registry = AdapterSpecificRegistry.new
+
+    class << self
+      attr_accessor :registry # :nodoc:
+      delegate :add_modifier, to: :registry
+
+      # Add a new type to the registry, allowing it to be referenced as a
+      # symbol by {ActiveRecord::Base.attribute}[rdoc-ref:Attributes::ClassMethods#attribute].
+      # If your type is only meant to be used with a specific database adapter, you can
+      # do so by passing <tt>adapter: :postgresql</tt>. If your type has the same
+      # name as a native type for the current adapter, an exception will be
+      # raised unless you specify an +:override+ option. <tt>override: true</tt> will
+      # cause your type to be used instead of the native type. <tt>override:
+      # false</tt> will cause the native type to be used over yours if one exists.
+      def register(type_name, klass = nil, **options, &block)
+        registry.register(type_name, klass, **options, &block)
+      end
+
+      def lookup(*args, adapter: current_adapter_name, **kwargs) # :nodoc:
+        registry.lookup(*args, adapter: adapter, **kwargs)
+      end
+
+      private
+
+      def current_adapter_name
+        ActiveRecord::Base.connection.adapter_name.downcase.to_sym
+      end
+    end
+
+    Helpers = ActiveModel::Type::Helpers
+    BigInteger = ActiveModel::Type::BigInteger
+    Binary = ActiveModel::Type::Binary
+    Boolean = ActiveModel::Type::Boolean
+    Decimal = ActiveModel::Type::Decimal
+    DecimalWithoutScale = ActiveModel::Type::DecimalWithoutScale
+    Float = ActiveModel::Type::Float
+    Integer = ActiveModel::Type::Integer
+    String = ActiveModel::Type::String
+    Text = ActiveModel::Type::Text
+    UnsignedInteger = ActiveModel::Type::UnsignedInteger
+    Value = ActiveModel::Type::Value
+
+    register(:big_integer, Type::BigInteger, override: false)
+    register(:binary, Type::Binary, override: false)
+    register(:boolean, Type::Boolean, override: false)
+    register(:date, Type::Date, override: false)
+    register(:date_time, Type::DateTime, override: false)
+    register(:decimal, Type::Decimal, override: false)
+    register(:float, Type::Float, override: false)
+    register(:integer, Type::Integer, override: false)
+    register(:string, Type::String, override: false)
+    register(:text, Type::Text, override: false)
+    register(:time, Type::Time, override: false)
+  end
+end
diff --git a/activerecord/lib/active_record/type/adapter_specific_registry.rb b/activerecord/lib/active_record/type/adapter_specific_registry.rb
new file mode 100644
index 0000000000..d440eac619
--- /dev/null
+++ b/activerecord/lib/active_record/type/adapter_specific_registry.rb
@@ -0,0 +1,130 @@
+require 'active_model/type/registry'
+
+module ActiveRecord
+  # :stopdoc:
+  module Type
+    class AdapterSpecificRegistry < ActiveModel::Type::Registry
+      def add_modifier(options, klass, **args)
+        registrations << DecorationRegistration.new(options, klass, **args)
+      end
+
+      private
+
+      def registration_klass
+        Registration
+      end
+
+      def find_registration(symbol, *args)
+        registrations
+          .select { |registration| registration.matches?(symbol, *args) }
+          .max
+      end
+    end
+
+    class Registration
+      def initialize(name, block, adapter: nil, override: nil)
+        @name = name
+        @block = block
+        @adapter = adapter
+        @override = override
+      end
+
+      def call(_registry, *args, adapter: nil, **kwargs)
+        if kwargs.any? # https://bugs.ruby-lang.org/issues/10856
+          block.call(*args, **kwargs)
+        else
+          block.call(*args)
+        end
+      end
+
+      def matches?(type_name, *args, **kwargs)
+        type_name == name && matches_adapter?(**kwargs)
+      end
+
+      def <=>(other)
+        if conflicts_with?(other)
+          raise TypeConflictError.new("Type #{name} was registered for all
+                                      adapters, but shadows a native type with
+                                      the same name for #{other.adapter}".squish)
+        end
+        priority <=> other.priority
+      end
+
+      protected
+
+      attr_reader :name, :block, :adapter, :override
+
+      def priority
+        result = 0
+        if adapter
+          result |= 1
+        end
+        if override
+          result |= 2
+        end
+        result
+      end
+
+      def priority_except_adapter
+        priority & 0b111111100
+      end
+
+      private
+
+      def matches_adapter?(adapter: nil, **)
+        (self.adapter.nil? || adapter == self.adapter)
+      end
+
+      def conflicts_with?(other)
+        same_priority_except_adapter?(other) &&
+          has_adapter_conflict?(other)
+      end
+
+      def same_priority_except_adapter?(other)
+        priority_except_adapter == other.priority_except_adapter
+      end
+
+      def has_adapter_conflict?(other)
+        (override.nil? && other.adapter) ||
+          (adapter && other.override.nil?)
+      end
+    end
+
+    class DecorationRegistration < Registration
+      def initialize(options, klass, adapter: nil)
+        @options = options
+        @klass = klass
+        @adapter = adapter
+      end
+
+      def call(registry, *args, **kwargs)
+        subtype = registry.lookup(*args, **kwargs.except(*options.keys))
+        klass.new(subtype)
+      end
+
+      def matches?(*args, **kwargs)
+        matches_adapter?(**kwargs) && matches_options?(**kwargs)
+      end
+
+      def priority
+        super | 4
+      end
+
+      protected
+
+      attr_reader :options, :klass
+
+      private
+
+      def matches_options?(**kwargs)
+        options.all? do |key, value|
+          kwargs[key] == value
+        end
+      end
+    end
+  end
+
+  class TypeConflictError < StandardError
+  end
+  # :startdoc:
+end
diff --git a/activerecord/lib/active_record/type/date.rb b/activerecord/lib/active_record/type/date.rb
index d90a6069b7..ccafed054e 100644
--- a/activerecord/lib/active_record/type/date.rb
+++ b/activerecord/lib/active_record/type/date.rb
@@ -1,46 +1,7 @@
 module ActiveRecord
   module Type
-    class Date < Value # :nodoc:
-      def type
-        :date
-      end
-
-      def klass
-        ::Date
-      end
-
-      def type_cast_for_schema(value)
-        "'#{value.to_s(:db)}'"
-      end
-
-      private
-
-      def cast_value(value)
-        if value.is_a?(::String)
-          return if value.empty?
-          fast_string_to_date(value) || fallback_string_to_date(value)
-        elsif value.respond_to?(:to_date)
-          value.to_date
-        else
-          value
-        end
-      end
-
-      def fast_string_to_date(string)
-        if string =~ ConnectionAdapters::Column::Format::ISO_DATE
-          new_date $1.to_i, $2.to_i, $3.to_i
-        end
-      end
-
-      def fallback_string_to_date(string)
-        new_date(*::Date._parse(string, false).values_at(:year, :mon, :mday))
-      end
-
-      def new_date(year, mon, mday)
-        if year && year != 0
-          ::Date.new(year, mon, mday) rescue nil
-        end
-      end
+    class Date < ActiveModel::Type::Date
+      include Internal::Timezone
     end
   end
 end
diff --git a/activerecord/lib/active_record/type/date_time.rb b/activerecord/lib/active_record/type/date_time.rb
index 0a737815bc..1fb9380ecd 100644
--- a/activerecord/lib/active_record/type/date_time.rb
+++ b/activerecord/lib/active_record/type/date_time.rb
@@ -1,47 +1,7 @@
 module ActiveRecord
   module Type
-    class DateTime < Value # :nodoc:
-      include TimeValue
-
-      def type
-        :datetime
-      end
-
-      def type_cast_for_database(value)
-        zone_conversion_method = ActiveRecord::Base.default_timezone == :utc ? :getutc : :getlocal
-
-        if value.acts_like?(:time)
-          if value.respond_to?(zone_conversion_method)
-            value.send(zone_conversion_method)
-          else
-            value
-          end
-        else
-          super
-        end
-      end
-
-      private
-
-      def cast_value(string)
-        return string unless string.is_a?(::String)
-        return if string.empty?
-
-        fast_string_to_time(string) || fallback_string_to_time(string)
-      end
-
-      # '0.123456' -> 123456
-      # '1.123456' -> 123456
-      def microseconds(time)
-        time[:sec_fraction] ? (time[:sec_fraction] * 1_000_000).to_i : 0
-      end
-
-      def fallback_string_to_time(string)
-        time_hash = ::Date._parse(string)
-        time_hash[:sec_fraction] = microseconds(time_hash)
-
-        new_time(*time_hash.values_at(:year, :mon, :mday, :hour, :min, :sec, :sec_fraction, :offset))
-      end
+    class DateTime < ActiveModel::Type::DateTime
+      include Internal::Timezone
     end
   end
 end
diff --git a/activerecord/lib/active_record/type/decorator.rb b/activerecord/lib/active_record/type/decorator.rb
deleted file mode 100644
index 9fce38ea44..0000000000
--- a/activerecord/lib/active_record/type/decorator.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-module ActiveRecord
-  module Type
-    module Decorator # :nodoc:
-      def init_with(coder)
-        @subtype = coder['subtype']
-        __setobj__(@subtype)
-      end
-
-      def encode_with(coder)
-        coder['subtype'] = __getobj__
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/type/float.rb b/activerecord/lib/active_record/type/float.rb
deleted file mode 100644
index 42eb44b9a9..0000000000
--- a/activerecord/lib/active_record/type/float.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-module ActiveRecord
-  module Type
-    class Float < Value # :nodoc:
-      include Numeric
-
-      def type
-        :float
-      end
-
-      alias type_cast_for_database type_cast
-
-      private
-
-      def cast_value(value)
-        value.to_f
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/type/hash_lookup_type_map.rb b/activerecord/lib/active_record/type/hash_lookup_type_map.rb
index 82d9327fc0..3b01e3f8ca 100644
--- a/activerecord/lib/active_record/type/hash_lookup_type_map.rb
+++ b/activerecord/lib/active_record/type/hash_lookup_type_map.rb
@@ -1,12 +1,18 @@
 module ActiveRecord
   module Type
     class HashLookupTypeMap < TypeMap # :nodoc:
-      delegate :key?, to: :@mapping
-
       def alias_type(type, alias_type)
         register_type(type) { |_, *args| lookup(alias_type, *args) }
       end
 
+      def key?(key)
+        @mapping.key?(key)
+      end
+
+      def keys
+        @mapping.keys
+      end
+
       private
 
       def perform_fetch(type, *args, &block)
diff --git a/activerecord/lib/active_record/type/internal/abstract_json.rb b/activerecord/lib/active_record/type/internal/abstract_json.rb
new file mode 100644
index 0000000000..097d1bd363
--- /dev/null
+++ b/activerecord/lib/active_record/type/internal/abstract_json.rb
@@ -0,0 +1,33 @@
+module ActiveRecord
+  module Type
+    module Internal # :nodoc:
+      class AbstractJson < ActiveModel::Type::Value # :nodoc:
+        include ActiveModel::Type::Helpers::Mutable
+
+        def type
+          :json
+        end
+
+        def deserialize(value)
+          if value.is_a?(::String)
+            ::ActiveSupport::JSON.decode(value) rescue nil
+          else
+            value
+          end
+        end
+
+        def serialize(value)
+          if value.is_a?(::Array) || value.is_a?(::Hash)
+            ::ActiveSupport::JSON.encode(value)
+          else
+            value
+          end
+        end
+
+        def accessor
+          ActiveRecord::Store::StringKeyedHashAccessor
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/type/internal/timezone.rb b/activerecord/lib/active_record/type/internal/timezone.rb
new file mode 100644
index 0000000000..947e06158a
--- /dev/null
+++ b/activerecord/lib/active_record/type/internal/timezone.rb
@@ -0,0 +1,15 @@
+module ActiveRecord
+  module Type
+    module Internal
+      module Timezone
+        def is_utc?
+          ActiveRecord::Base.default_timezone == :utc
+        end
+
+        def default_timezone
+          ActiveRecord::Base.default_timezone
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/type/mutable.rb b/activerecord/lib/active_record/type/mutable.rb
deleted file mode 100644
index 066617ea59..0000000000
--- a/activerecord/lib/active_record/type/mutable.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-module ActiveRecord
-  module Type
-    module Mutable # :nodoc:
-      def type_cast_from_user(value)
-        type_cast_from_database(type_cast_for_database(value))
-      end
-
-      # +raw_old_value+ will be the `_before_type_cast` version of the
-      # value (likely a string). +new_value+ will be the current, type
-      # cast value.
-      def changed_in_place?(raw_old_value, new_value)
-        raw_old_value != type_cast_for_database(new_value)
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/type/numeric.rb b/activerecord/lib/active_record/type/numeric.rb
deleted file mode 100644
index 674f996f38..0000000000
--- a/activerecord/lib/active_record/type/numeric.rb
+++ /dev/null
@@ -1,36 +0,0 @@
-module ActiveRecord
-  module Type
-    module Numeric # :nodoc:
-      def number?
-        true
-      end
-
-      def type_cast(value)
-        value = case value
-                when true then 1
-                when false then 0
-                when ::String then value.presence
-                else value
-                end
-        super(value)
-      end
-
-      def changed?(old_value, _new_value, new_value_before_type_cast) # :nodoc:
-        super || number_to_non_number?(old_value, new_value_before_type_cast)
-      end
-
-      private
-
-      def number_to_non_number?(old_value, new_value_before_type_cast)
-        old_value != nil && non_numeric_string?(new_value_before_type_cast)
-      end
-
-      def non_numeric_string?(value)
-        # 'wibble'.to_i will give zero, we want to make sure
-        # that we aren't marking int zero to string zero as
-        # changed.
-        value.to_s !~ /\A-?\d+\.?\d*\z/
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/type/serialized.rb b/activerecord/lib/active_record/type/serialized.rb
index 3cac03464e..4ff0740cfb 100644
--- a/activerecord/lib/active_record/type/serialized.rb
+++ b/activerecord/lib/active_record/type/serialized.rb
@@ -1,8 +1,7 @@
 module ActiveRecord
   module Type
-    class Serialized < DelegateClass(Type::Value) # :nodoc:
-      include Mutable
-      include Decorator
+    class Serialized < DelegateClass(ActiveModel::Type::Value) # :nodoc:
+      include ActiveModel::Type::Helpers::Mutable
 
       attr_reader :subtype, :coder
 
@@ -12,7 +11,7 @@ module ActiveRecord
         super(subtype)
       end
 
-      def type_cast_from_database(value)
+      def deserialize(value)
         if default_value?(value)
           value
         else
@@ -20,30 +19,32 @@ module ActiveRecord
         end
       end
 
-      def type_cast_for_database(value)
+      def serialize(value)
         return if value.nil?
         unless default_value?(value)
           super coder.dump(value)
         end
       end
 
+      def inspect
+        Kernel.instance_method(:inspect).bind(self).call
+      end
+
       def changed_in_place?(raw_old_value, value)
         return false if value.nil?
-        subtype.changed_in_place?(raw_old_value, type_cast_for_database(value))
+        raw_new_value = serialize(value)
+        raw_old_value.nil? != raw_new_value.nil? ||
+          subtype.changed_in_place?(raw_old_value, raw_new_value)
       end
 
       def accessor
         ActiveRecord::Store::IndifferentHashAccessor
       end
 
-      def init_with(coder)
-        @coder = coder['coder']
-        super
-      end
-
-      def encode_with(coder)
-        coder['coder'] = @coder
-        super
+      def assert_valid_value(value)
+        if coder.respond_to?(:assert_valid_value)
+          coder.assert_valid_value(value)
+        end
       end
 
       private
diff --git a/activerecord/lib/active_record/type/string.rb b/activerecord/lib/active_record/type/string.rb
deleted file mode 100644
index cf95e25be0..0000000000
--- a/activerecord/lib/active_record/type/string.rb
+++ /dev/null
@@ -1,40 +0,0 @@
-module ActiveRecord
-  module Type
-    class String < Value # :nodoc:
-      def type
-        :string
-      end
-
-      def changed_in_place?(raw_old_value, new_value)
-        if new_value.is_a?(::String)
-          raw_old_value != new_value
-        end
-      end
-
-      def type_cast_for_database(value)
-        case value
-        when ::Numeric, ActiveSupport::Duration then value.to_s
-        when ::String then ::String.new(value)
-        when true then "t"
-        when false then "f"
-        else super
-        end
-      end
-
-      def text?
-        true
-      end
-
-      private
-
-      def cast_value(value)
-        case value
-        when true then "t"
-        when false then "f"
-        # String.new is slightly faster than dup
-        else ::String.new(value.to_s)
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/type/time.rb b/activerecord/lib/active_record/type/time.rb
index cab1c7bf1e..70988d84ff 100644
--- a/activerecord/lib/active_record/type/time.rb
+++ b/activerecord/lib/active_record/type/time.rb
@@ -1,39 +1,8 @@
 module ActiveRecord
   module Type
-    class Time < Value # :nodoc:
-      include TimeValue
-
-      def type
-        :time
-      end
-
-      def user_input_in_time_zone(value)
-        return unless value.present?
-
-        case value
-        when ::String
-          value = "2000-01-01 #{value}"
-        when ::Time
-          value = value.change(year: 2000, day: 1, month: 1)
-        end
-
-        super(value)
-      end
-
-      private
-
-      def cast_value(value)
-        return value unless value.is_a?(::String)
-        return if value.empty?
-
-        dummy_time_value = "2000-01-01 #{value}"
-
-        fast_string_to_time(dummy_time_value) || begin
-          time_hash = ::Date._parse(dummy_time_value)
-          return if time_hash[:hour].nil?
-          new_time(*time_hash.values_at(:year, :mon, :mday, :hour, :min, :sec, :sec_fraction))
-        end
-      end
+    class Time < ActiveModel::Type::Time
+      include Internal::Timezone
     end
   end
 end
+
diff --git a/activerecord/lib/active_record/type/time_value.rb b/activerecord/lib/active_record/type/time_value.rb
deleted file mode 100644
index 8d9ac25643..0000000000
--- a/activerecord/lib/active_record/type/time_value.rb
+++ /dev/null
@@ -1,42 +0,0 @@
-module ActiveRecord
-  module Type
-    module TimeValue # :nodoc:
-      def klass
-        ::Time
-      end
-
-      def type_cast_for_schema(value)
-        "'#{value.to_s(:db)}'"
-      end
-
-      def user_input_in_time_zone(value)
-        value.in_time_zone
-      end
-
-      private
-
-      def new_time(year, mon, mday, hour, min, sec, microsec, offset = nil)
-        # Treat 0000-00-00 00:00:00 as nil.
-        return if year.nil? || (year == 0 && mon == 0 && mday == 0)
-
-        if offset
-          time = ::Time.utc(year, mon, mday, hour, min, sec, microsec) rescue nil
-          return unless time
-
-          time -= offset
-          Base.default_timezone == :utc ? time : time.getlocal
-        else
-          ::Time.public_send(Base.default_timezone, year, mon, mday, hour, min, sec, microsec) rescue nil
-        end
-      end
-
-      # Doesn't handle time zones.
-      def fast_string_to_time(string)
-        if string =~ ConnectionAdapters::Column::Format::ISO_DATETIME
-          microsec = ($7.to_r * 1_000_000).to_i
-          new_time $1.to_i, $2.to_i, $3.to_i, $4.to_i, $5.to_i, $6.to_i, microsec
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/type/type_map.rb b/activerecord/lib/active_record/type/type_map.rb
index 09f5ba6b74..81d7ed39bb 100644
--- a/activerecord/lib/active_record/type/type_map.rb
+++ b/activerecord/lib/active_record/type/type_map.rb
@@ -1,12 +1,12 @@
-require 'thread_safe'
+require 'concurrent'
 
 module ActiveRecord
   module Type
     class TypeMap # :nodoc:
       def initialize
         @mapping = {}
-        @cache = ThreadSafe::Cache.new do |h, key|
-          h.fetch_or_store(key, ThreadSafe::Cache.new)
+        @cache = Concurrent::Map.new do |h, key|
+          h.fetch_or_store(key, Concurrent::Map.new)
         end
       end
 
@@ -57,7 +57,7 @@ module ActiveRecord
       end
 
       def default_value
-        @default_value ||= Value.new
+        @default_value ||= ActiveModel::Type::Value.new
       end
     end
   end
diff --git a/activerecord/lib/active_record/type/value.rb b/activerecord/lib/active_record/type/value.rb
deleted file mode 100644
index 859b51ca90..0000000000
--- a/activerecord/lib/active_record/type/value.rb
+++ /dev/null
@@ -1,104 +0,0 @@
-module ActiveRecord
-  module Type
-    class Value # :nodoc:
-      attr_reader :precision, :scale, :limit
-
-      # Valid options are +precision+, +scale+, and +limit+.
-      def initialize(options = {})
-        options.assert_valid_keys(:precision, :scale, :limit)
-        @precision = options[:precision]
-        @scale = options[:scale]
-        @limit = options[:limit]
-      end
-
-      # The simplified type that this object represents. Returns a symbol such
-      # as +:string+ or +:integer+
-      def type; end
-
-      # Type casts a string from the database into the appropriate ruby type.
-      # Classes which do not need separate type casting behavior for database
-      # and user provided values should override +cast_value+ instead.
-      def type_cast_from_database(value)
-        type_cast(value)
-      end
-
-      # Type casts a value from user input (e.g. from a setter). This value may
-      # be a string from the form builder, or an already type cast value
-      # provided manually to a setter.
-      #
-      # Classes which do not need separate type casting behavior for database
-      # and user provided values should override +type_cast+ or +cast_value+
-      # instead.
-      def type_cast_from_user(value)
-        type_cast(value)
-      end
-
-      # Cast a value from the ruby type to a type that the database knows how
-      # to understand. The returned value from this method should be a
-      # +String+, +Numeric+, +Date+, +Time+, +Symbol+, +true+, +false+, or
-      # +nil+
-      def type_cast_for_database(value)
-        value
-      end
-
-      # Type cast a value for schema dumping. This method is private, as we are
-      # hoping to remove it entirely.
-      def type_cast_for_schema(value) # :nodoc:
-        value.inspect
-      end
-
-      # These predicates are not documented, as I need to look further into
-      # their use, and see if they can be removed entirely.
-      def text? # :nodoc:
-        false
-      end
-
-      def number? # :nodoc:
-        false
-      end
-
-      def binary? # :nodoc:
-        false
-      end
-
-      def klass # :nodoc:
-      end
-
-      # Determines whether a value has changed for dirty checking. +old_value+
-      # and +new_value+ will always be type-cast. Types should not need to
-      # override this method.
-      def changed?(old_value, new_value, _new_value_before_type_cast)
-        old_value != new_value
-      end
-
-      # Determines whether the mutable value has been modified since it was
-      # read. Returns +false+ by default. This method should not be overridden
-      # directly. Types which return a mutable value should include
-      # +Type::Mutable+, which will define this method.
-      def changed_in_place?(*)
-        false
-      end
-
-      def ==(other)
-        self.class == other.class &&
-          precision == other.precision &&
-          scale == other.scale &&
-          limit == other.limit
-      end
-
-      private
-
-      def type_cast(value)
-        cast_value(value) unless value.nil?
-      end
-
-      # Convenience method for types which do not need separate type casting
-      # behavior for user and database inputs. Called by
-      # +type_cast_from_database+ and +type_cast_from_user+ for all values
-      # except +nil+.
-      def cast_value(value) # :doc:
-        value
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/type_caster/connection.rb b/activerecord/lib/active_record/type_caster/connection.rb
index 9e4a130b40..868d08ed44 100644
--- a/activerecord/lib/active_record/type_caster/connection.rb
+++ b/activerecord/lib/active_record/type_caster/connection.rb
@@ -1,33 +1,28 @@
 module ActiveRecord
   module TypeCaster
     class Connection
-      def initialize(connection, table_name)
-        @connection = connection
+      def initialize(klass, table_name)
+        @klass = klass
         @table_name = table_name
       end
 
       def type_cast_for_database(attribute_name, value)
         return value if value.is_a?(Arel::Nodes::BindParam)
-        type = type_for(attribute_name)
-        type.type_cast_for_database(value)
+        column = column_for(attribute_name)
+        connection.type_cast_from_column(column, value)
       end
 
       protected
 
-      attr_reader :connection, :table_name
+      attr_reader :table_name
+      delegate :connection, to: :@klass
 
       private
 
-      def type_for(attribute_name)
-        if connection.schema_cache.table_exists?(table_name)
-          column_for(attribute_name).cast_type
-        else
-          Type::Value.new
-        end
-      end
-
       def column_for(attribute_name)
-        connection.schema_cache.columns_hash(table_name)[attribute_name.to_s]
+        if connection.schema_cache.data_source_exists?(table_name)
+          connection.schema_cache.columns_hash(table_name)[attribute_name.to_s]
+        end
       end
     end
   end
diff --git a/activerecord/lib/active_record/type_caster/map.rb b/activerecord/lib/active_record/type_caster/map.rb
index 03c9e8ff83..4b1941351c 100644
--- a/activerecord/lib/active_record/type_caster/map.rb
+++ b/activerecord/lib/active_record/type_caster/map.rb
@@ -8,7 +8,7 @@ module ActiveRecord
       def type_cast_for_database(attr_name, value)
         return value if value.is_a?(Arel::Nodes::BindParam)
         type = types.type_for_attribute(attr_name.to_s)
-        type.type_cast_for_database(value)
+        type.serialize(value)
       end
 
       protected
diff --git a/activerecord/lib/active_record/validations.rb b/activerecord/lib/active_record/validations.rb
index f27adc9c40..6677e6dc5f 100644
--- a/activerecord/lib/active_record/validations.rb
+++ b/activerecord/lib/active_record/validations.rb
@@ -1,8 +1,9 @@
 module ActiveRecord
-  # = Active Record RecordInvalid
+  # = Active Record \RecordInvalid
   #
-  # Raised by <tt>save!</tt> and <tt>create!</tt> when the record is invalid. Use the
-  # +record+ method to retrieve the record which did not validate.
+  # Raised by {ActiveRecord::Base#save!}[rdoc-ref:Persistence#save!] and
+  # {ActiveRecord::Base#create!}[rdoc-ref:Persistence::ClassMethods#create!] when the record is invalid.
+  # Use the #record method to retrieve the record which did not validate.
   #
   #   begin
   #     complex_operation_that_internally_calls_save!
@@ -12,70 +13,68 @@ module ActiveRecord
   class RecordInvalid < ActiveRecordError
     attr_reader :record
 
-    def initialize(record)
-      @record = record
-      errors = @record.errors.full_messages.join(", ")
-      super(I18n.t(:"#{@record.class.i18n_scope}.errors.messages.record_invalid", :errors => errors, :default => :"errors.messages.record_invalid"))
+    def initialize(record = nil)
+      if record
+        @record = record
+        errors = @record.errors.full_messages.join(", ")
+        message = I18n.t(:"#{@record.class.i18n_scope}.errors.messages.record_invalid", errors: errors, default: :"errors.messages.record_invalid")
+      else
+        message = "Record invalid"
+      end
+
+      super(message)
     end
   end
 
-  # = Active Record Validations
+  # = Active Record \Validations
   #
-  # Active Record includes the majority of its validations from <tt>ActiveModel::Validations</tt>
+  # Active Record includes the majority of its validations from ActiveModel::Validations
   # all of which accept the <tt>:on</tt> argument to define the context where the
   # validations are active. Active Record will always supply either the context of
   # <tt>:create</tt> or <tt>:update</tt> dependent on whether the model is a
-  # <tt>new_record?</tt>.
+  # {new_record?}[rdoc-ref:Persistence#new_record?].
   module Validations
     extend ActiveSupport::Concern
     include ActiveModel::Validations
 
     # The validation process on save can be skipped by passing <tt>validate: false</tt>.
-    # The regular Base#save method is replaced with this when the validations
-    # module is mixed in, which it is by default.
+    # The regular {ActiveRecord::Base#save}[rdoc-ref:Persistence#save] method is replaced
+    # with this when the validations module is mixed in, which it is by default.
     def save(options={})
       perform_validations(options) ? super : false
     end
 
-    # Attempts to save the record just like Base#save but will raise a +RecordInvalid+
-    # exception instead of returning +false+ if the record is not valid.
+    # Attempts to save the record just like {ActiveRecord::Base#save}[rdoc-ref:Base#save] but
+    # will raise a ActiveRecord::RecordInvalid exception instead of returning +false+ if the record is not valid.
     def save!(options={})
-      perform_validations(options) ? super : raise_record_invalid
+      perform_validations(options) ? super : raise_validation_error
     end
 
     # Runs all the validations within the specified context. Returns +true+ if
     # no errors are found, +false+ otherwise.
     #
-    # Aliased as validate.
+    # Aliased as #validate.
     #
     # If the argument is +false+ (default is +nil+), the context is set to <tt>:create</tt> if
-    # <tt>new_record?</tt> is +true+, and to <tt>:update</tt> if it is not.
+    # {new_record?}[rdoc-ref:Persistence#new_record?] is +true+, and to <tt>:update</tt> if it is not.
     #
-    # Validations with no <tt>:on</tt> option will run no matter the context. Validations with
+    # \Validations with no <tt>:on</tt> option will run no matter the context. \Validations with
     # some <tt>:on</tt> option will only run in the specified context.
     def valid?(context = nil)
-      context ||= (new_record? ? :create : :update)
+      context ||= default_validation_context
       output = super(context)
       errors.empty? && output
     end
 
     alias_method :validate, :valid?
 
-    # Runs all the validations within the specified context. Returns +true+ if
-    # no errors are found, raises +RecordInvalid+ otherwise.
-    #
-    # If the argument is +false+ (default is +nil+), the context is set to <tt>:create</tt> if
-    # <tt>new_record?</tt> is +true+, and to <tt>:update</tt> if it is not.
-    #
-    # Validations with no <tt>:on</tt> option will run no matter the context. Validations with
-    # some <tt>:on</tt> option will only run in the specified context.
-    def validate!(context = nil)
-      valid?(context) || raise_record_invalid
-    end
-
   protected
 
-    def raise_record_invalid
+    def default_validation_context
+      new_record? ? :create : :update
+    end
+
+    def raise_validation_error
       raise(RecordInvalid.new(self))
     end
 
@@ -88,4 +87,5 @@ end
 require "active_record/validations/associated"
 require "active_record/validations/uniqueness"
 require "active_record/validations/presence"
+require "active_record/validations/absence"
 require "active_record/validations/length"
diff --git a/activerecord/lib/active_record/validations/absence.rb b/activerecord/lib/active_record/validations/absence.rb
new file mode 100644
index 0000000000..2e19e6dc5c
--- /dev/null
+++ b/activerecord/lib/active_record/validations/absence.rb
@@ -0,0 +1,24 @@
+module ActiveRecord
+  module Validations
+    class AbsenceValidator < ActiveModel::Validations::AbsenceValidator # :nodoc:
+      def validate_each(record, attribute, association_or_value)
+        return unless should_validate?(record)
+        if record.class._reflect_on_association(attribute)
+          association_or_value = Array.wrap(association_or_value).reject(&:marked_for_destruction?)
+        end
+        super
+      end
+    end
+
+    module ClassMethods
+      # Validates that the specified attributes are not present (as defined by
+      # Object#present?). If the attribute is an association, the associated object
+      # is considered absent if it was marked for destruction.
+      #
+      # See ActiveModel::Validations::HelperMethods.validates_absence_of for more information.
+      def validates_absence_of(*attr_names)
+        validates_with AbsenceValidator, _merge_attributes(attr_names)
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/validations/associated.rb b/activerecord/lib/active_record/validations/associated.rb
index 47ccef31a5..32fbaf0a91 100644
--- a/activerecord/lib/active_record/validations/associated.rb
+++ b/activerecord/lib/active_record/validations/associated.rb
@@ -24,7 +24,8 @@ module ActiveRecord
       #
       # NOTE: This validation will not fail if the association hasn't been
       # assigned. If you want to ensure that the association is both present and
-      # guaranteed to be valid, you also need to use +validates_presence_of+.
+      # guaranteed to be valid, you also need to use
+      # {validates_presence_of}[rdoc-ref:Validations::ClassMethods#validates_presence_of].
       #
       # Configuration options:
       #
diff --git a/activerecord/lib/active_record/validations/length.rb b/activerecord/lib/active_record/validations/length.rb
index ef5a6cbbe7..69e048eef1 100644
--- a/activerecord/lib/active_record/validations/length.rb
+++ b/activerecord/lib/active_record/validations/length.rb
@@ -2,15 +2,30 @@ module ActiveRecord
   module Validations
     class LengthValidator < ActiveModel::Validations::LengthValidator # :nodoc:
       def validate_each(record, attribute, association_or_value)
+        return unless should_validate?(record) || associations_are_dirty?(record)
         if association_or_value.respond_to?(:loaded?) && association_or_value.loaded?
           association_or_value = association_or_value.target.reject(&:marked_for_destruction?)
         end
         super
       end
+
+      def associations_are_dirty?(record)
+        attributes.any? do |attribute|
+          value = record.read_attribute_for_validation(attribute)
+          if value.respond_to?(:loaded?) && value.loaded?
+            value.target.any?(&:marked_for_destruction?)
+          else
+            false
+          end
+        end
+      end
     end
 
     module ClassMethods
-      # See <tt>ActiveModel::Validation::LengthValidator</tt> for more information.
+      # Validates that the specified attributes match the length restrictions supplied.
+      # If the attribute is an association, records that are marked for destruction are not counted.
+      #
+      # See ActiveModel::Validations::HelperMethods.validates_length_of for more information.
       def validates_length_of(*attr_names)
         validates_with LengthValidator, _merge_attributes(attr_names)
       end
diff --git a/activerecord/lib/active_record/validations/presence.rb b/activerecord/lib/active_record/validations/presence.rb
index 61b30749d9..7e85ed43ac 100644
--- a/activerecord/lib/active_record/validations/presence.rb
+++ b/activerecord/lib/active_record/validations/presence.rb
@@ -1,17 +1,12 @@
 module ActiveRecord
   module Validations
     class PresenceValidator < ActiveModel::Validations::PresenceValidator # :nodoc:
-      def validate(record)
-        super
-        attributes.each do |attribute|
-          next unless record.class._reflect_on_association(attribute)
-          associated_records = Array.wrap(record.send(attribute))
-
-          # Superclass validates presence. Ensure present records aren't about to be destroyed.
-          if associated_records.present? && associated_records.all?(&:marked_for_destruction?)
-            record.errors.add(attribute, :blank, options)
-          end
+      def validate_each(record, attribute, association_or_value)
+        return unless should_validate?(record)
+        if record.class._reflect_on_association(attribute)
+          association_or_value = Array.wrap(association_or_value).reject(&:marked_for_destruction?)
         end
+        super
       end
     end
 
@@ -36,12 +31,17 @@ module ActiveRecord
       # This is due to the way Object#blank? handles boolean values:
       # <tt>false.blank? # => true</tt>.
       #
-      # This validator defers to the ActiveModel validation for presence, adding the
+      # This validator defers to the Active Model validation for presence, adding the
       # check to see that an associated object is not marked for destruction. This
       # prevents the parent object from validating successfully and saving, which then
       # deletes the associated object, thus putting the parent object into an invalid
       # state.
       #
+      # NOTE: This validation will not fail while using it with an association
+      # if the latter was assigned but not valid. If you want to ensure that
+      # it is both present and valid, you also need to use
+      # {validates_associated}[rdoc-ref:Validations::ClassMethods#validates_associated].
+      #
       # Configuration options:
       # * <tt>:message</tt> - A custom error message (default is: "can't be blank").
       # * <tt>:on</tt> - Specifies the contexts where this validation is active.
@@ -58,7 +58,7 @@ module ActiveRecord
       #   or <tt>unless: Proc.new { |user| user.signup_step <= 2 }</tt>). The method,
       #   proc or string should return or evaluate to a +true+ or +false+ value.
       # * <tt>:strict</tt> - Specifies whether validation should be strict.
-      #   See <tt>ActiveModel::Validation#validates!</tt> for more information.
+      #   See ActiveModel::Validation#validates! for more information.
       def validates_presence_of(*attr_names)
         validates_with PresenceValidator, _merge_attributes(attr_names)
       end
diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index f52f91e89c..aa2794f120 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -11,12 +11,19 @@ module ActiveRecord
       end
 
       def validate_each(record, attribute, value)
+        return unless should_validate?(record)
         finder_class = find_finder_class_for(record)
         table = finder_class.arel_table
         value = map_enum_attribute(finder_class, attribute, value)
 
         relation = build_relation(finder_class, table, attribute, value)
-        relation = relation.where.not(finder_class.primary_key => record.id) if record.persisted?
+        if record.persisted? && finder_class.primary_key.to_s != attribute.to_s
+          if finder_class.primary_key
+            relation = relation.where.not(finder_class.primary_key => record.id)
+          else
+            raise UnknownPrimaryKey.new(finder_class, "Can not validate uniqueness for persisted record without primary key.")
+          end
+        end
         relation = scope_relation(record, table, relation)
         relation = relation.merge(options[:conditions]) if options[:conditions]
 
@@ -59,7 +66,8 @@ module ActiveRecord
         end
 
         column = klass.columns_hash[attribute_name]
-        value = klass.type_for_attribute(attribute_name).type_cast_for_database(value)
+        cast_type = klass.type_for_attribute(attribute_name)
+        value = cast_type.serialize(value)
         value = klass.connection.type_cast(value)
         if value.is_a?(String) && column.limit
           value = value.to_s[0, column.limit]
@@ -67,13 +75,15 @@ module ActiveRecord
 
         value = Arel::Nodes::Quoted.new(value)
 
-        comparison = if !options[:case_sensitive] && value && column.text?
+        comparison = if !options[:case_sensitive] && !value.nil?
           # will use SQL LOWER function before comparison, unless it detects a case insensitive collation
           klass.connection.case_insensitive_comparison(table, attribute, column, value)
         else
           klass.connection.case_sensitive_comparison(table, attribute, column, value)
         end
         klass.unscoped.where(comparison)
+      rescue RangeError
+        klass.none
       end
 
       def scope_relation(record, table, relation)
@@ -162,7 +172,8 @@ module ActiveRecord
       #
       # === Concurrency and integrity
       #
-      # Using this validation method in conjunction with ActiveRecord::Base#save
+      # Using this validation method in conjunction with
+      # {ActiveRecord::Base#save}[rdoc-ref:Persistence#save]
       # does not guarantee the absence of duplicate record insertions, because
       # uniqueness checks on the application level are inherently prone to race
       # conditions. For example, suppose that two users try to post a Comment at
@@ -199,12 +210,12 @@ module ActiveRecord
       # This could even happen if you use transactions with the 'serializable'
       # isolation level. The best way to work around this problem is to add a unique
       # index to the database table using
-      # ActiveRecord::ConnectionAdapters::SchemaStatements#add_index. In the
-      # rare case that a race condition occurs, the database will guarantee
+      # {connection.add_index}[rdoc-ref:ConnectionAdapters::SchemaStatements#add_index].
+      # In the rare case that a race condition occurs, the database will guarantee
       # the field's uniqueness.
       #
       # When the database catches such a duplicate insertion,
-      # ActiveRecord::Base#save will raise an ActiveRecord::StatementInvalid
+      # {ActiveRecord::Base#save}[rdoc-ref:Persistence#save] will raise an ActiveRecord::StatementInvalid
       # exception. You can either choose to let this error propagate (which
       # will result in the default Rails exception page being shown), or you
       # can catch it and restart the transaction (e.g. by telling the user
diff --git a/activerecord/lib/rails/generators/active_record/migration.rb b/activerecord/lib/rails/generators/active_record/migration.rb
index b7418cf42f..c2b2209638 100644
--- a/activerecord/lib/rails/generators/active_record/migration.rb
+++ b/activerecord/lib/rails/generators/active_record/migration.rb
@@ -13,6 +13,13 @@ module ActiveRecord
           ActiveRecord::Migration.next_migration_number(next_migration_number)
         end
       end
+
+      private
+
+        def primary_key_type
+          key_type = options[:primary_key_type]
+          ", id: :#{key_type}" if key_type
+        end
     end
   end
 end
diff --git a/activerecord/lib/rails/generators/active_record/migration/migration_generator.rb b/activerecord/lib/rails/generators/active_record/migration/migration_generator.rb
index 7a3c6f5e95..4e5872b585 100644
--- a/activerecord/lib/rails/generators/active_record/migration/migration_generator.rb
+++ b/activerecord/lib/rails/generators/active_record/migration/migration_generator.rb
@@ -5,6 +5,8 @@ module ActiveRecord
     class MigrationGenerator < Base # :nodoc:
       argument :attributes, :type => :array, :default => [], :banner => "field[:type][:index] field[:type][:index]"
 
+      class_option :primary_key_type, type: :string, desc: "The type for primary key"
+
       def create_migration_file
         set_local_assigns!
         validate_file_name!
@@ -14,10 +16,9 @@ module ActiveRecord
       protected
       attr_reader :migration_action, :join_tables
 
-      # sets the default migration template that is being used for the generation of the migration
-      # depending on the arguments which would be sent out in the command line, the migration template 
-      # and the table name instance variables are setup.
-
+      # Sets the default migration template that is being used for the generation of the migration.
+      # Depending on command line arguments, the migration template and the table name instance
+      # variables are set up.
       def set_local_assigns!
         @migration_template = "migration.rb"
         case file_name
@@ -56,6 +57,8 @@ module ActiveRecord
           attributes.select { |a| !a.reference? && a.has_index? }
         end
 
+        # A migration file name can only contain underscores (_), lowercase characters,
+        # and numbers 0-9. Any other file name will raise an IllegalMigrationNameError.
         def validate_file_name!
           unless file_name =~ /^[_a-z0-9]+$/
             raise IllegalMigrationNameError.new(file_name)
diff --git a/activerecord/lib/rails/generators/active_record/migration/templates/create_table_migration.rb b/activerecord/lib/rails/generators/active_record/migration/templates/create_table_migration.rb
index 5b3e57dcf6..fadab2a1e6 100644
--- a/activerecord/lib/rails/generators/active_record/migration/templates/create_table_migration.rb
+++ b/activerecord/lib/rails/generators/active_record/migration/templates/create_table_migration.rb
@@ -1,6 +1,6 @@
 class <%= migration_class_name %> < ActiveRecord::Migration
   def change
-    create_table :<%= table_name %> do |t|
+    create_table :<%= table_name %><%= primary_key_type %> do |t|
 <% attributes.each do |attribute| -%>
 <% if attribute.password_digest? -%>
       t.string :password_digest<%= attribute.inject_options %>
diff --git a/activerecord/lib/rails/generators/active_record/model/model_generator.rb b/activerecord/lib/rails/generators/active_record/model/model_generator.rb
index 7e8d68ce69..395951ac9d 100644
--- a/activerecord/lib/rails/generators/active_record/model/model_generator.rb
+++ b/activerecord/lib/rails/generators/active_record/model/model_generator.rb
@@ -7,14 +7,13 @@ module ActiveRecord
 
       check_class_collision
 
-      class_option :migration,  :type => :boolean
-      class_option :timestamps, :type => :boolean
-      class_option :parent,     :type => :string, :desc => "The parent class for the generated model"
-      class_option :indexes,    :type => :boolean, :default => true, :desc => "Add indexes for references and belongs_to columns"
+      class_option :migration, type: :boolean
+      class_option :timestamps, type: :boolean
+      class_option :parent, type: :string, desc: "The parent class for the generated model"
+      class_option :indexes, type: :boolean, default: true, desc: "Add indexes for references and belongs_to columns"
+      class_option :primary_key_type, type: :string, desc: "The type for primary key"
 
-      
       # creates the migration file for the model.
-
       def create_migration_file
         return unless options[:migration] && options[:parent].nil?
         attributes.each { |a| a.attr_options.delete(:index) if a.reference? && !a.has_index? } if options[:indexes] == false
diff --git a/activerecord/test/active_record/connection_adapters/fake_adapter.rb b/activerecord/test/active_record/connection_adapters/fake_adapter.rb
index 64cde143a1..43c817e057 100644
--- a/activerecord/test/active_record/connection_adapters/fake_adapter.rb
+++ b/activerecord/test/active_record/connection_adapters/fake_adapter.rb
@@ -7,7 +7,7 @@ module ActiveRecord
 
   module ConnectionAdapters
     class FakeAdapter < AbstractAdapter
-      attr_accessor :tables, :primary_keys
+      attr_accessor :data_sources, :primary_keys
 
       @columns = Hash.new { |h,k| h[k] = [] }
       class << self
@@ -16,21 +16,20 @@ module ActiveRecord
 
       def initialize(connection, logger)
         super
-        @tables       = []
+        @data_sources = []
         @primary_keys = {}
         @columns      = self.class.columns
       end
 
       def primary_key(table)
-        @primary_keys[table]
+        @primary_keys[table] || "id"
       end
 
       def merge_column(table_name, name, sql_type = nil, options = {})
         @columns[table_name] << ActiveRecord::ConnectionAdapters::Column.new(
           name.to_s,
           options[:default],
-          lookup_cast_type(sql_type.to_s),
-          sql_type.to_s,
+          fetch_type_metadata(sql_type),
           options[:null])
       end
 
@@ -38,6 +37,10 @@ module ActiveRecord
         @columns[table_name]
       end
 
+      def data_source_exists?(*)
+        true
+      end
+
       def active?
         true
       end
diff --git a/activerecord/test/cases/adapter_test.rb b/activerecord/test/cases/adapter_test.rb
index 99e3d7021d..62579a4a7a 100644
--- a/activerecord/test/cases/adapter_test.rb
+++ b/activerecord/test/cases/adapter_test.rb
@@ -36,6 +36,21 @@ module ActiveRecord
       assert !@connection.table_exists?(nil)
     end
 
+    def test_data_sources
+      data_sources = @connection.data_sources
+      assert data_sources.include?("accounts")
+      assert data_sources.include?("authors")
+      assert data_sources.include?("tasks")
+      assert data_sources.include?("topics")
+    end
+
+    def test_data_source_exists?
+      assert @connection.data_source_exists?("accounts")
+      assert @connection.data_source_exists?(:accounts)
+      assert_not @connection.data_source_exists?("nonexistingtable")
+      assert_not @connection.data_source_exists?(nil)
+    end
+
     def test_indexes
       idx_name = "accounts_idx"
 
@@ -63,7 +78,7 @@ module ActiveRecord
       end
     end
 
-    if current_adapter?(:MysqlAdapter)
+    if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
       def test_charset
         assert_not_nil @connection.charset
         assert_not_equal 'character_set_database', @connection.charset
@@ -193,7 +208,7 @@ module ActiveRecord
       author = Author.create!(name: 'john')
       Post.create!(author: author, title: 'foo', body: 'bar')
       query = author.posts.where(title: 'foo').select(:title)
-      assert_equal({"title" => "foo"}, @connection.select_one(query.arel, nil, query.bind_values))
+      assert_equal({"title" => "foo"}, @connection.select_one(query.arel, nil, query.bound_attributes))
       assert_equal({"title" => "foo"}, @connection.select_one(query))
       assert @connection.select_all(query).is_a?(ActiveRecord::Result)
       assert_equal "foo", @connection.select_value(query)
@@ -203,7 +218,7 @@ module ActiveRecord
     def test_select_methods_passing_a_relation
       Post.create!(title: 'foo', body: 'bar')
       query = Post.where(title: 'foo').select(:title)
-      assert_equal({"title" => "foo"}, @connection.select_one(query.arel, nil, query.bind_values))
+      assert_equal({"title" => "foo"}, @connection.select_one(query.arel, nil, query.bound_attributes))
       assert_equal({"title" => "foo"}, @connection.select_one(query))
       assert @connection.select_all(query).is_a?(ActiveRecord::Result)
       assert_equal "foo", @connection.select_value(query)
@@ -226,7 +241,7 @@ module ActiveRecord
   end
 
   class AdapterTestWithoutTransaction < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     class Klass < ActiveRecord::Base
     end
diff --git a/activerecord/test/cases/adapters/mysql/active_schema_test.rb b/activerecord/test/cases/adapters/mysql/active_schema_test.rb
index 6577d56240..0b5c9e1798 100644
--- a/activerecord/test/cases/adapters/mysql/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/mysql/active_schema_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 require 'support/connection_helper'
 
-class ActiveSchemaTest < ActiveRecord::TestCase
+class MysqlActiveSchemaTest < ActiveRecord::MysqlTestCase
   include ConnectionHelper
 
   def setup
@@ -59,21 +59,56 @@ class ActiveSchemaTest < ActiveRecord::TestCase
     assert_equal expected, add_index(:people, [:last_name, :first_name], :length => 15, :using => :btree)
   end
 
-  def test_drop_table
-    assert_equal "DROP TABLE `people`", drop_table(:people)
+  def test_index_in_create
+    def (ActiveRecord::Base.connection).table_exists?(*); false; end
+
+    %w(SPATIAL FULLTEXT UNIQUE).each do |type|
+      expected = "CREATE TABLE `people` (#{type} INDEX `index_people_on_last_name`  (`last_name`) ) ENGINE=InnoDB"
+      actual = ActiveRecord::Base.connection.create_table(:people, id: false) do |t|
+        t.index :last_name, type: type
+      end
+      assert_equal expected, actual
+    end
+
+    expected = "CREATE TABLE `people` ( INDEX `index_people_on_last_name` USING btree (`last_name`(10)) ) ENGINE=InnoDB"
+    actual = ActiveRecord::Base.connection.create_table(:people, id: false) do |t|
+      t.index :last_name, length: 10, using: :btree
+    end
+    assert_equal expected, actual
   end
 
-  if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
-    def test_create_mysql_database_with_encoding
-      assert_equal "CREATE DATABASE `matt` DEFAULT CHARACTER SET `utf8`", create_database(:matt)
-      assert_equal "CREATE DATABASE `aimonetti` DEFAULT CHARACTER SET `latin1`", create_database(:aimonetti, {:charset => 'latin1'})
-      assert_equal "CREATE DATABASE `matt_aimonetti` DEFAULT CHARACTER SET `big5` COLLATE `big5_chinese_ci`", create_database(:matt_aimonetti, {:charset => :big5, :collation => :big5_chinese_ci})
+  def test_index_in_bulk_change
+    def (ActiveRecord::Base.connection).table_exists?(*); true; end
+    def (ActiveRecord::Base.connection).index_name_exists?(*); false; end
+
+    %w(SPATIAL FULLTEXT UNIQUE).each do |type|
+      expected = "ALTER TABLE `people` ADD #{type} INDEX `index_people_on_last_name`  (`last_name`)"
+      actual = ActiveRecord::Base.connection.change_table(:people, bulk: true) do |t|
+        t.index :last_name, type: type
+      end
+      assert_equal expected, actual
     end
 
-    def test_recreate_mysql_database_with_encoding
-      create_database(:luca, {:charset => 'latin1'})
-      assert_equal "CREATE DATABASE `luca` DEFAULT CHARACTER SET `latin1`", recreate_database(:luca, {:charset => 'latin1'})
+    expected = "ALTER TABLE `peaple` ADD  INDEX `index_peaple_on_last_name` USING btree (`last_name`(10)), ALGORITHM = COPY"
+    actual = ActiveRecord::Base.connection.change_table(:peaple, bulk: true) do |t|
+      t.index :last_name, length: 10, using: :btree, algorithm: :copy
     end
+    assert_equal expected, actual
+  end
+
+  def test_drop_table
+    assert_equal "DROP TABLE `people`", drop_table(:people)
+  end
+
+  def test_create_mysql_database_with_encoding
+    assert_equal "CREATE DATABASE `matt` DEFAULT CHARACTER SET `utf8`", create_database(:matt)
+    assert_equal "CREATE DATABASE `aimonetti` DEFAULT CHARACTER SET `latin1`", create_database(:aimonetti, {:charset => 'latin1'})
+    assert_equal "CREATE DATABASE `matt_aimonetti` DEFAULT CHARACTER SET `big5` COLLATE `big5_chinese_ci`", create_database(:matt_aimonetti, {:charset => :big5, :collation => :big5_chinese_ci})
+  end
+
+  def test_recreate_mysql_database_with_encoding
+    create_database(:luca, {:charset => 'latin1'})
+    assert_equal "CREATE DATABASE `luca` DEFAULT CHARACTER SET `latin1`", recreate_database(:luca, {:charset => 'latin1'})
   end
 
   def test_add_column
diff --git a/activerecord/test/cases/adapters/mysql/case_sensitivity_test.rb b/activerecord/test/cases/adapters/mysql/case_sensitivity_test.rb
index 340fc95503..98d44315dd 100644
--- a/activerecord/test/cases/adapters/mysql/case_sensitivity_test.rb
+++ b/activerecord/test/cases/adapters/mysql/case_sensitivity_test.rb
@@ -1,7 +1,6 @@
 require "cases/helper"
-require 'models/person'
 
-class MysqlCaseSensitivityTest < ActiveRecord::TestCase
+class MysqlCaseSensitivityTest < ActiveRecord::MysqlTestCase
   class CollationTest < ActiveRecord::Base
   end
 
diff --git a/activerecord/test/cases/adapters/mysql/charset_collation_test.rb b/activerecord/test/cases/adapters/mysql/charset_collation_test.rb
new file mode 100644
index 0000000000..f2117a97e6
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql/charset_collation_test.rb
@@ -0,0 +1,54 @@
+require "cases/helper"
+require 'support/schema_dumping_helper'
+
+class MysqlCharsetCollationTest < ActiveRecord::MysqlTestCase
+  include SchemaDumpingHelper
+  self.use_transactional_tests = false
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table :charset_collations, force: true do |t|
+      t.string :string_ascii_bin, charset: 'ascii', collation: 'ascii_bin'
+      t.text :text_ucs2_unicode_ci, charset: 'ucs2', collation: 'ucs2_unicode_ci'
+    end
+  end
+
+  teardown do
+    @connection.drop_table :charset_collations, if_exists: true
+  end
+
+  test "string column with charset and collation" do
+    column = @connection.columns(:charset_collations).find { |c| c.name == 'string_ascii_bin' }
+    assert_equal :string, column.type
+    assert_equal 'ascii_bin', column.collation
+  end
+
+  test "text column with charset and collation" do
+    column = @connection.columns(:charset_collations).find { |c| c.name == 'text_ucs2_unicode_ci' }
+    assert_equal :text, column.type
+    assert_equal 'ucs2_unicode_ci', column.collation
+  end
+
+  test "add column with charset and collation" do
+    @connection.add_column :charset_collations, :title, :string, charset: 'utf8', collation: 'utf8_bin'
+
+    column = @connection.columns(:charset_collations).find { |c| c.name == 'title' }
+    assert_equal :string, column.type
+    assert_equal 'utf8_bin', column.collation
+  end
+
+  test "change column with charset and collation" do
+    @connection.add_column :charset_collations, :description, :string, charset: 'utf8', collation: 'utf8_unicode_ci'
+    @connection.change_column :charset_collations, :description, :text, charset: 'utf8', collation: 'utf8_general_ci'
+
+    column = @connection.columns(:charset_collations).find { |c| c.name == 'description' }
+    assert_equal :text, column.type
+    assert_equal 'utf8_general_ci', column.collation
+  end
+
+  test "schema dump includes collation" do
+    output = dump_table_schema("charset_collations")
+    assert_match %r{t.string\s+"string_ascii_bin",\s+limit: 255,\s+collation: "ascii_bin"$}, output
+    assert_match %r{t.text\s+"text_ucs2_unicode_ci",\s+limit: 65535,\s+collation: "ucs2_unicode_ci"$}, output
+  end
+end
diff --git a/activerecord/test/cases/adapters/mysql/connection_test.rb b/activerecord/test/cases/adapters/mysql/connection_test.rb
index ce01b16362..decac9e83b 100644
--- a/activerecord/test/cases/adapters/mysql/connection_test.rb
+++ b/activerecord/test/cases/adapters/mysql/connection_test.rb
@@ -2,7 +2,7 @@ require "cases/helper"
 require 'support/connection_helper'
 require 'support/ddl_helper'
 
-class MysqlConnectionTest < ActiveRecord::TestCase
+class MysqlConnectionTest < ActiveRecord::MysqlTestCase
   include ConnectionHelper
   include DdlHelper
 
@@ -26,7 +26,7 @@ class MysqlConnectionTest < ActiveRecord::TestCase
       run_without_connection do
         ar_config = ARTest.connection_config['arunit']
 
-        url = "mysql://#{ar_config["username"]}@localhost/#{ar_config["database"]}"
+        url = "mysql://#{ar_config["username"]}:#{ar_config["password"]}@localhost/#{ar_config["database"]}"
         Klass.establish_connection(url)
         assert_equal ar_config['database'], Klass.connection.current_database
       end
@@ -94,7 +94,7 @@ class MysqlConnectionTest < ActiveRecord::TestCase
     with_example_table do
       @connection.exec_query('INSERT INTO ex (id, data) VALUES (1, "foo")')
       result = @connection.exec_query(
-        'SELECT id, data FROM ex WHERE id = ?', nil, [[nil, 1]])
+        'SELECT id, data FROM ex WHERE id = ?', nil, [ActiveRecord::Relation::QueryAttribute.new("id", 1, ActiveRecord::Type::Value.new)])
 
       assert_equal 1, result.rows.length
       assert_equal 2, result.columns.length
@@ -106,10 +106,10 @@ class MysqlConnectionTest < ActiveRecord::TestCase
   def test_exec_typecasts_bind_vals
     with_example_table do
       @connection.exec_query('INSERT INTO ex (id, data) VALUES (1, "foo")')
-      column = @connection.columns('ex').find { |col| col.name == 'id' }
+      bind = ActiveRecord::Relation::QueryAttribute.new("id", "1-fuu", ActiveRecord::Type::Integer.new)
 
       result = @connection.exec_query(
-        'SELECT id, data FROM ex WHERE id = ?', nil, [[column, '1-fuu']])
+        'SELECT id, data FROM ex WHERE id = ?', nil, [bind])
 
       assert_equal 1, result.rows.length
       assert_equal 2, result.columns.length
@@ -118,15 +118,6 @@ class MysqlConnectionTest < ActiveRecord::TestCase
     end
   end
 
-  # Test that MySQL allows multiple results for stored procedures
-  if defined?(Mysql) && Mysql.const_defined?(:CLIENT_MULTI_RESULTS)
-    def test_multi_results
-      rows = ActiveRecord::Base.connection.select_rows('CALL ten();')
-      assert_equal 10, rows[0][0].to_i, "ten() did not return 10 as expected: #{rows.inspect}"
-      assert @connection.active?, "Bad connection use by 'MysqlAdapter.select_rows'"
-    end
-  end
-
   def test_mysql_connection_collation_is_configured
     assert_equal 'utf8_unicode_ci', @connection.show_variable('collation_connection')
     assert_equal 'utf8_general_ci', ARUnit2Model.connection.show_variable('collation_connection')
@@ -145,6 +136,15 @@ class MysqlConnectionTest < ActiveRecord::TestCase
     end
   end
 
+  def test_mysql_strict_mode_specified_default
+    run_without_connection do |orig_connection|
+      ActiveRecord::Base.establish_connection(orig_connection.merge({strict: :default}))
+      global_sql_mode = ActiveRecord::Base.connection.exec_query "SELECT @@GLOBAL.sql_mode"
+      session_sql_mode = ActiveRecord::Base.connection.exec_query "SELECT @@SESSION.sql_mode"
+      assert_equal global_sql_mode.rows, session_sql_mode.rows
+    end
+  end
+
   def test_mysql_set_session_variable
     run_without_connection do |orig_connection|
       ActiveRecord::Base.establish_connection(orig_connection.deep_merge({:variables => {:default_week_format => 3}}))
@@ -174,7 +174,7 @@ class MysqlConnectionTest < ActiveRecord::TestCase
 
   def with_example_table(&block)
     definition ||= <<-SQL
-      `id` int(11) auto_increment PRIMARY KEY,
+      `id` int auto_increment PRIMARY KEY,
       `data` varchar(255)
     SQL
     super(@connection, 'ex', definition, &block)
diff --git a/activerecord/test/cases/adapters/mysql/consistency_test.rb b/activerecord/test/cases/adapters/mysql/consistency_test.rb
index e972d6b330..743f6436e4 100644
--- a/activerecord/test/cases/adapters/mysql/consistency_test.rb
+++ b/activerecord/test/cases/adapters/mysql/consistency_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 
-class MysqlConsistencyTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+class MysqlConsistencyTest < ActiveRecord::MysqlTestCase
+  self.use_transactional_tests = false
 
   class Consistency < ActiveRecord::Base
     self.table_name = "mysql_consistency"
diff --git a/activerecord/test/cases/adapters/mysql/datetime_test.rb b/activerecord/test/cases/adapters/mysql/datetime_test.rb
deleted file mode 100644
index ae00f4e131..0000000000
--- a/activerecord/test/cases/adapters/mysql/datetime_test.rb
+++ /dev/null
@@ -1,87 +0,0 @@
-require 'cases/helper'
-
-if mysql_56?
-  class DateTimeTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
-
-    class Foo < ActiveRecord::Base; end
-
-    def test_default_datetime_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true)
-      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime
-      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime
-      assert_nil activerecord_column_option('foos', 'created_at', 'precision')
-    end
-
-    def test_datetime_data_type_with_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true)
-      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime, precision: 1
-      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime, precision: 5
-      assert_equal 1, activerecord_column_option('foos', 'created_at', 'precision')
-      assert_equal 5, activerecord_column_option('foos', 'updated_at', 'precision')
-    end
-
-    def test_timestamps_helper_with_custom_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-        t.timestamps null: true, precision: 4
-      end
-      assert_equal 4, activerecord_column_option('foos', 'created_at', 'precision')
-      assert_equal 4, activerecord_column_option('foos', 'updated_at', 'precision')
-    end
-
-    def test_passing_precision_to_datetime_does_not_set_limit
-      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-        t.timestamps null: true, precision: 4
-      end
-      assert_nil activerecord_column_option('foos', 'created_at', 'limit')
-      assert_nil activerecord_column_option('foos', 'updated_at', 'limit')
-    end
-
-    def test_invalid_datetime_precision_raises_error
-      assert_raises ActiveRecord::ActiveRecordError do
-        ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-          t.timestamps null: true, precision: 7
-        end
-      end
-    end
-
-    def test_mysql_agrees_with_activerecord_about_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-        t.timestamps null: true, precision: 4
-      end
-      assert_equal 4, mysql_datetime_precision('foos', 'created_at')
-      assert_equal 4, mysql_datetime_precision('foos', 'updated_at')
-    end
-
-    def test_formatting_datetime_according_to_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-        t.datetime :created_at, precision: 0
-        t.datetime :updated_at, precision: 4
-      end
-      date = ::Time.utc(2014, 8, 17, 12, 30, 0, 999999)
-      Foo.create!(created_at: date, updated_at: date)
-      assert foo = Foo.find_by(created_at: date)
-      assert_equal date.to_s, foo.created_at.to_s
-      assert_equal date.to_s, foo.updated_at.to_s
-      assert_equal 000000, foo.created_at.usec
-      assert_equal 999900, foo.updated_at.usec
-    end
-
-    private
-
-    def mysql_datetime_precision(table_name, column_name)
-      results = ActiveRecord::Base.connection.exec_query("SELECT column_name, datetime_precision FROM information_schema.columns WHERE table_name = '#{table_name}'")
-      result = results.find do |result_hash|
-        result_hash["column_name"] == column_name
-      end
-      result && result["datetime_precision"]
-    end
-
-    def activerecord_column_option(tablename, column_name, option)
-      result = ActiveRecord::Base.connection.columns(tablename).find do |column|
-        column.name == column_name
-      end
-      result && result.send(option)
-    end
-  end
-end
diff --git a/activerecord/test/cases/adapters/mysql/enum_test.rb b/activerecord/test/cases/adapters/mysql/enum_test.rb
index f4e7a3ef0a..ef8ee0a6e3 100644
--- a/activerecord/test/cases/adapters/mysql/enum_test.rb
+++ b/activerecord/test/cases/adapters/mysql/enum_test.rb
@@ -1,6 +1,6 @@
 require "cases/helper"
 
-class MysqlEnumTest < ActiveRecord::TestCase
+class MysqlEnumTest < ActiveRecord::MysqlTestCase
   class EnumTest < ActiveRecord::Base
   end
 
diff --git a/activerecord/test/cases/adapters/mysql/explain_test.rb b/activerecord/test/cases/adapters/mysql/explain_test.rb
new file mode 100644
index 0000000000..c44c1e6648
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql/explain_test.rb
@@ -0,0 +1,21 @@
+require "cases/helper"
+require 'models/developer'
+require 'models/computer'
+
+class MysqlExplainTest < ActiveRecord::MysqlTestCase
+  fixtures :developers
+
+  def test_explain_for_one_query
+    explain = Developer.where(id: 1).explain
+    assert_match %(EXPLAIN for: SELECT `developers`.* FROM `developers` WHERE `developers`.`id` = 1), explain
+    assert_match %r(developers |.* const), explain
+  end
+
+  def test_explain_with_eager_loading
+    explain = Developer.where(id: 1).includes(:audit_logs).explain
+    assert_match %(EXPLAIN for: SELECT `developers`.* FROM `developers` WHERE `developers`.`id` = 1), explain
+    assert_match %r(developers |.* const), explain
+    assert_match %(EXPLAIN for: SELECT `audit_logs`.* FROM `audit_logs` WHERE `audit_logs`.`developer_id` = 1), explain
+    assert_match %r(audit_logs |.* ALL), explain
+  end
+end
diff --git a/activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb b/activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb
index 85db8f4614..d2ce48fc00 100644
--- a/activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb
@@ -1,11 +1,9 @@
-# encoding: utf-8
-
 require "cases/helper"
 require 'support/ddl_helper'
 
 module ActiveRecord
   module ConnectionAdapters
-    class MysqlAdapterTest < ActiveRecord::TestCase
+    class MysqlAdapterTest < ActiveRecord::MysqlTestCase
       include DdlHelper
 
       def setup
@@ -16,7 +14,7 @@ module ActiveRecord
         assert_raise ActiveRecord::NoDatabaseError do
           configuration = ActiveRecord::Base.configurations['arunit'].merge(database: 'inexistent_activerecord_unittest')
           connection = ActiveRecord::Base.mysql_connection(configuration)
-          connection.exec_query('drop table if exists ex')
+          connection.drop_table 'ex', if_exists: true
         end
       end
 
@@ -67,40 +65,8 @@ module ActiveRecord
         end
       end
 
-      def test_tables_quoting
-        @conn.tables(nil, "foo-bar", nil)
-        flunk
-      rescue => e
-        # assertion for *quoted* database properly
-        assert_match(/database 'foo-bar'/, e.inspect)
-      end
-
-      def test_pk_and_sequence_for
-        with_example_table do
-          pk, seq = @conn.pk_and_sequence_for('ex')
-          assert_equal 'id', pk
-          assert_equal @conn.default_sequence_name('ex', 'id'), seq
-        end
-      end
-
-      def test_pk_and_sequence_for_with_non_standard_primary_key
-        with_example_table '`code` INT(11) auto_increment, PRIMARY KEY (`code`)' do
-          pk, seq = @conn.pk_and_sequence_for('ex')
-          assert_equal 'code', pk
-          assert_equal @conn.default_sequence_name('ex', 'code'), seq
-        end
-      end
-
-      def test_pk_and_sequence_for_with_custom_index_type_pk
-        with_example_table '`id` INT(11) auto_increment, PRIMARY KEY USING BTREE (`id`)' do
-          pk, seq = @conn.pk_and_sequence_for('ex')
-          assert_equal 'id', pk
-          assert_equal @conn.default_sequence_name('ex', 'id'), seq
-        end
-      end
-
       def test_composite_primary_key
-        with_example_table '`id` INT(11), `number` INT(11), foo INT(11), PRIMARY KEY (`id`, `number`)' do
+        with_example_table '`id` INT, `number` INT, foo INT, PRIMARY KEY (`id`, `number`)' do
           assert_nil @conn.primary_key('ex')
         end
       end
@@ -111,7 +77,7 @@ module ActiveRecord
 
           result = @conn.exec_query('SELECT status FROM ex')
 
-          assert_equal 2, result.column_types['status'].type_cast_from_database(result.last['status'])
+          assert_equal 2, result.column_types['status'].deserialize(result.last['status'])
         end
       end
 
@@ -129,10 +95,10 @@ module ActiveRecord
 
       private
       def insert(ctx, data, table='ex')
-        binds   = data.map { |name, value|
-          [ctx.columns(table).find { |x| x.name == name }, value]
+        binds = data.map { |name, value|
+          Relation::QueryAttribute.new(name, value, Type::Value.new)
         }
-        columns = binds.map(&:first).map(&:name)
+        columns = binds.map(&:name)
 
         sql = "INSERT INTO #{table} (#{columns.join(", ")})
                VALUES (#{(['?'] * columns.length).join(', ')})"
@@ -142,7 +108,7 @@ module ActiveRecord
 
       def with_example_table(definition = nil, &block)
         definition ||= <<-SQL
-          `id` int(11) auto_increment PRIMARY KEY,
+          `id` int auto_increment PRIMARY KEY,
           `number` integer,
           `data` varchar(255)
         SQL
diff --git a/activerecord/test/cases/adapters/mysql/quoting_test.rb b/activerecord/test/cases/adapters/mysql/quoting_test.rb
index a2206153e9..2024aa36ab 100644
--- a/activerecord/test/cases/adapters/mysql/quoting_test.rb
+++ b/activerecord/test/cases/adapters/mysql/quoting_test.rb
@@ -1,21 +1,29 @@
 require "cases/helper"
 
-module ActiveRecord
-  module ConnectionAdapters
-    class MysqlAdapter
-      class QuotingTest < ActiveRecord::TestCase
-        def setup
-          @conn = ActiveRecord::Base.connection
-        end
+class MysqlQuotingTest < ActiveRecord::MysqlTestCase
+  def setup
+    @conn = ActiveRecord::Base.connection
+  end
+
+  def test_type_cast_true
+    assert_equal 1, @conn.type_cast(true)
+  end
 
-        def test_type_cast_true
-          assert_equal 1, @conn.type_cast(true)
-        end
+  def test_type_cast_false
+    assert_equal 0, @conn.type_cast(false)
+  end
+
+  def test_quoted_date_precision_for_gte_564
+    @conn.stubs(:full_version).returns('5.6.4')
+    @conn.remove_instance_variable(:@version) if @conn.instance_variable_defined?(:@version)
+    t = Time.now.change(usec: 1)
+    assert_match(/\.000001\z/, @conn.quoted_date(t))
+  end
 
-        def test_type_cast_false
-          assert_equal 0, @conn.type_cast(false)
-        end
-      end
-    end
+  def test_quoted_date_precision_for_lt_564
+    @conn.stubs(:full_version).returns('5.6.3')
+    @conn.remove_instance_variable(:@version) if @conn.instance_variable_defined?(:@version)
+    t = Time.now.change(usec: 1)
+    assert_no_match(/\.000001\z/, @conn.quoted_date(t))
   end
 end
diff --git a/activerecord/test/cases/adapters/mysql/reserved_word_test.rb b/activerecord/test/cases/adapters/mysql/reserved_word_test.rb
index 403f7cbc74..4ea1d9ad36 100644
--- a/activerecord/test/cases/adapters/mysql/reserved_word_test.rb
+++ b/activerecord/test/cases/adapters/mysql/reserved_word_test.rb
@@ -1,29 +1,29 @@
 require "cases/helper"
 
-class Group < ActiveRecord::Base
-  Group.table_name = 'group'
-  belongs_to :select
-  has_one :values
-end
+# a suite of tests to ensure the ConnectionAdapters#MysqlAdapter can handle tables with
+# reserved word names (ie: group, order, values, etc...)
+class MysqlReservedWordTest < ActiveRecord::MysqlTestCase
+  class Group < ActiveRecord::Base
+    Group.table_name = 'group'
+    belongs_to :select
+    has_one :values
+  end
 
-class Select < ActiveRecord::Base
-  Select.table_name = 'select'
-  has_many :groups
-end
+  class Select < ActiveRecord::Base
+    Select.table_name = 'select'
+    has_many :groups
+  end
 
-class Values < ActiveRecord::Base
-  Values.table_name = 'values'
-end
+  class Values < ActiveRecord::Base
+    Values.table_name = 'values'
+  end
 
-class Distinct < ActiveRecord::Base
-  Distinct.table_name = 'distinct'
-  has_and_belongs_to_many :selects
-  has_many :values, :through => :groups
-end
+  class Distinct < ActiveRecord::Base
+    Distinct.table_name = 'distinct'
+    has_and_belongs_to_many :selects
+    has_many :values, :through => :groups
+  end
 
-# a suite of tests to ensure the ConnectionAdapters#MysqlAdapter can handle tables with
-# reserved word names (ie: group, order, values, etc...)
-class MysqlReservedWordTest < ActiveRecord::TestCase
   def setup
     @connection = ActiveRecord::Base.connection
 
@@ -71,7 +71,7 @@ class MysqlReservedWordTest < ActiveRecord::TestCase
 
   #fixtures
   self.use_instantiated_fixtures = true
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   #activerecord model class with reserved-word table name
   def test_activerecord_model
@@ -139,7 +139,7 @@ class MysqlReservedWordTest < ActiveRecord::TestCase
   # custom drop table, uses execute on connection to drop a table if it exists. note: escapes table_name
   def drop_tables_directly(table_names, connection = @connection)
     table_names.each do |name|
-      connection.execute("DROP TABLE IF EXISTS `#{name}`")
+      connection.drop_table name, if_exists: true
     end
   end
 
diff --git a/activerecord/test/cases/adapters/mysql/schema_test.rb b/activerecord/test/cases/adapters/mysql/schema_test.rb
index ab547747df..2e18f609fd 100644
--- a/activerecord/test/cases/adapters/mysql/schema_test.rb
+++ b/activerecord/test/cases/adapters/mysql/schema_test.rb
@@ -4,7 +4,7 @@ require 'models/comment'
 
 module ActiveRecord
   module ConnectionAdapters
-    class MysqlSchemaTest < ActiveRecord::TestCase
+    class MysqlSchemaTest < ActiveRecord::MysqlTestCase
       fixtures :posts
 
       def setup
@@ -22,7 +22,7 @@ module ActiveRecord
       end
 
       teardown do
-        @connection.execute "drop table if exists mysql_doubles"
+        @connection.drop_table "mysql_doubles", if_exists: true
       end
 
       class MysqlDouble < ActiveRecord::Base
diff --git a/activerecord/test/cases/adapters/mysql/sp_test.rb b/activerecord/test/cases/adapters/mysql/sp_test.rb
index 3ca2917ca4..579c3273c6 100644
--- a/activerecord/test/cases/adapters/mysql/sp_test.rb
+++ b/activerecord/test/cases/adapters/mysql/sp_test.rb
@@ -1,15 +1,29 @@
 require "cases/helper"
 require 'models/topic'
+require 'models/reply'
 
-class StoredProcedureTest < ActiveRecord::TestCase
+class MysqlStoredProcedureTest < ActiveRecord::MysqlTestCase
   fixtures :topics
 
+  def setup
+    @connection = ActiveRecord::Base.connection
+  end
+
   # Test that MySQL allows multiple results for stored procedures
-  if Mysql.const_defined?(:CLIENT_MULTI_RESULTS)
+  #
+  # In MySQL 5.6, CLIENT_MULTI_RESULTS is enabled by default.
+  # http://dev.mysql.com/doc/refman/5.6/en/call.html
+  if ActiveRecord::Base.connection.version >= '5.6.0' || Mysql.const_defined?(:CLIENT_MULTI_RESULTS)
+    def test_multi_results
+      rows = @connection.select_rows('CALL ten();')
+      assert_equal 10, rows[0][0].to_i, "ten() did not return 10 as expected: #{rows.inspect}"
+      assert @connection.active?, "Bad connection use by 'MysqlAdapter.select_rows'"
+    end
+
     def test_multi_results_from_find_by_sql
-      topics = Topic.find_by_sql 'CALL topics();'
-      assert_equal 1, topics.size
-      assert ActiveRecord::Base.connection.active?, "Bad connection use by 'MysqlAdapter.select'"
+      topics = Topic.find_by_sql 'CALL topics(3);'
+      assert_equal 3, topics.size
+      assert @connection.active?, "Bad connection use by 'MysqlAdapter.select'"
     end
   end
 end
diff --git a/activerecord/test/cases/adapters/mysql/sql_types_test.rb b/activerecord/test/cases/adapters/mysql/sql_types_test.rb
index 1ddb1b91c9..d18579f242 100644
--- a/activerecord/test/cases/adapters/mysql/sql_types_test.rb
+++ b/activerecord/test/cases/adapters/mysql/sql_types_test.rb
@@ -1,10 +1,10 @@
 require "cases/helper"
 
-class SqlTypesTest < ActiveRecord::TestCase
+class MysqlSqlTypesTest < ActiveRecord::MysqlTestCase
   def test_binary_types
     assert_equal 'varbinary(64)', type_to_sql(:binary, 64)
     assert_equal 'varbinary(4095)', type_to_sql(:binary, 4095)
-    assert_equal 'blob(4096)', type_to_sql(:binary, 4096)
+    assert_equal 'blob', type_to_sql(:binary, 4096)
     assert_equal 'blob', type_to_sql(:binary)
   end
 
diff --git a/activerecord/test/cases/adapters/mysql/statement_pool_test.rb b/activerecord/test/cases/adapters/mysql/statement_pool_test.rb
index 209a0cf464..0d1f968022 100644
--- a/activerecord/test/cases/adapters/mysql/statement_pool_test.rb
+++ b/activerecord/test/cases/adapters/mysql/statement_pool_test.rb
@@ -1,23 +1,19 @@
 require 'cases/helper'
 
-module ActiveRecord::ConnectionAdapters
-  class MysqlAdapter
-    class StatementPoolTest < ActiveRecord::TestCase
-      if Process.respond_to?(:fork)
-        def test_cache_is_per_pid
-          cache = StatementPool.new nil, 10
-          cache['foo'] = 'bar'
-          assert_equal 'bar', cache['foo']
+class MysqlStatementPoolTest < ActiveRecord::MysqlTestCase
+  if Process.respond_to?(:fork)
+    def test_cache_is_per_pid
+      cache = ActiveRecord::ConnectionAdapters::MysqlAdapter::StatementPool.new(10)
+      cache['foo'] = 'bar'
+      assert_equal 'bar', cache['foo']
 
-          pid = fork {
-            lookup = cache['foo'];
-            exit!(!lookup)
-          }
+      pid = fork {
+        lookup = cache['foo'];
+        exit!(!lookup)
+      }
 
-          Process.waitpid pid
-          assert $?.success?, 'process should exit successfully'
-        end
-      end
+      Process.waitpid pid
+      assert $?.success?, 'process should exit successfully'
     end
   end
 end
diff --git a/activerecord/test/cases/adapters/mysql/table_options_test.rb b/activerecord/test/cases/adapters/mysql/table_options_test.rb
new file mode 100644
index 0000000000..99df6d6cba
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql/table_options_test.rb
@@ -0,0 +1,42 @@
+require "cases/helper"
+require 'support/schema_dumping_helper'
+
+class MysqlTableOptionsTest < ActiveRecord::MysqlTestCase
+  include SchemaDumpingHelper
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+  end
+
+  def teardown
+    @connection.drop_table "mysql_table_options", if_exists: true
+  end
+
+  test "table options with ENGINE" do
+    @connection.create_table "mysql_table_options", force: true, options: "ENGINE=MyISAM"
+    output = dump_table_schema("mysql_table_options")
+    options = %r{create_table "mysql_table_options", force: :cascade, options: "(?<options>.*)"}.match(output)[:options]
+    assert_match %r{ENGINE=MyISAM}, options
+  end
+
+  test "table options with ROW_FORMAT" do
+    @connection.create_table "mysql_table_options", force: true, options: "ROW_FORMAT=REDUNDANT"
+    output = dump_table_schema("mysql_table_options")
+    options = %r{create_table "mysql_table_options", force: :cascade, options: "(?<options>.*)"}.match(output)[:options]
+    assert_match %r{ROW_FORMAT=REDUNDANT}, options
+  end
+
+  test "table options with CHARSET" do
+    @connection.create_table "mysql_table_options", force: true, options: "CHARSET=utf8mb4"
+    output = dump_table_schema("mysql_table_options")
+    options = %r{create_table "mysql_table_options", force: :cascade, options: "(?<options>.*)"}.match(output)[:options]
+    assert_match %r{CHARSET=utf8mb4}, options
+  end
+
+  test "table options with COLLATE" do
+    @connection.create_table "mysql_table_options", force: true, options: "COLLATE=utf8mb4_bin"
+    output = dump_table_schema("mysql_table_options")
+    options = %r{create_table "mysql_table_options", force: :cascade, options: "(?<options>.*)"}.match(output)[:options]
+    assert_match %r{COLLATE=utf8mb4_bin}, options
+  end
+end
diff --git a/activerecord/test/cases/adapters/mysql/unsigned_type_test.rb b/activerecord/test/cases/adapters/mysql/unsigned_type_test.rb
index 8f521e9181..84c5394c2e 100644
--- a/activerecord/test/cases/adapters/mysql/unsigned_type_test.rb
+++ b/activerecord/test/cases/adapters/mysql/unsigned_type_test.rb
@@ -1,7 +1,9 @@
 require "cases/helper"
+require "support/schema_dumping_helper"
 
-class UnsignedTypeTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+class MysqlUnsignedTypeTest < ActiveRecord::MysqlTestCase
+  include SchemaDumpingHelper
+  self.use_transactional_tests = false
 
   class UnsignedType < ActiveRecord::Base
   end
@@ -9,12 +11,15 @@ class UnsignedTypeTest < ActiveRecord::TestCase
   setup do
     @connection = ActiveRecord::Base.connection
     @connection.create_table("unsigned_types", force: true) do |t|
-      t.column :unsigned_integer, "int unsigned"
+      t.integer :unsigned_integer, unsigned: true
+      t.bigint  :unsigned_bigint,  unsigned: true
+      t.float   :unsigned_float,   unsigned: true
+      t.decimal :unsigned_decimal, unsigned: true, precision: 10, scale: 2
     end
   end
 
   teardown do
-    @connection.drop_table "unsigned_types"
+    @connection.drop_table "unsigned_types", if_exists: true
   end
 
   test "unsigned int max value is in range" do
@@ -26,5 +31,35 @@ class UnsignedTypeTest < ActiveRecord::TestCase
     assert_raise(RangeError) do
       UnsignedType.create(unsigned_integer: -10)
     end
+    assert_raise(RangeError) do
+      UnsignedType.create(unsigned_bigint: -10)
+    end
+    assert_raise(ActiveRecord::StatementInvalid) do
+      UnsignedType.create(unsigned_float: -10.0)
+    end
+    assert_raise(ActiveRecord::StatementInvalid) do
+      UnsignedType.create(unsigned_decimal: -10.0)
+    end
+  end
+
+  test "schema definition can use unsigned as the type" do
+    @connection.change_table("unsigned_types") do |t|
+      t.unsigned_integer :unsigned_integer_t
+      t.unsigned_bigint  :unsigned_bigint_t
+      t.unsigned_float   :unsigned_float_t
+      t.unsigned_decimal :unsigned_decimal_t, precision: 10, scale: 2
+    end
+
+    @connection.columns("unsigned_types").select { |c| /^unsigned_/ === c.name }.each do |column|
+      assert column.unsigned?
+    end
+  end
+
+  test "schema dump includes unsigned option" do
+    schema = dump_table_schema "unsigned_types"
+    assert_match %r{t.integer\s+"unsigned_integer",\s+limit: 4,\s+unsigned: true$}, schema
+    assert_match %r{t.integer\s+"unsigned_bigint",\s+limit: 8,\s+unsigned: true$}, schema
+    assert_match %r{t.float\s+"unsigned_float",\s+limit: 24,\s+unsigned: true$}, schema
+    assert_match %r{t.decimal\s+"unsigned_decimal",\s+precision: 10,\s+scale: 2,\s+unsigned: true$}, schema
   end
 end
diff --git a/activerecord/test/cases/adapters/mysql2/active_schema_test.rb b/activerecord/test/cases/adapters/mysql2/active_schema_test.rb
index e87cd3886a..31dc69a45b 100644
--- a/activerecord/test/cases/adapters/mysql2/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/active_schema_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 require 'support/connection_helper'
 
-class ActiveSchemaTest < ActiveRecord::TestCase
+class Mysql2ActiveSchemaTest < ActiveRecord::Mysql2TestCase
   include ConnectionHelper
 
   def setup
@@ -59,21 +59,56 @@ class ActiveSchemaTest < ActiveRecord::TestCase
     assert_equal expected, add_index(:people, [:last_name, :first_name], :length => 15, :using => :btree)
   end
 
-  def test_drop_table
-    assert_equal "DROP TABLE `people`", drop_table(:people)
+  def test_index_in_create
+    def (ActiveRecord::Base.connection).table_exists?(*); false; end
+
+    %w(SPATIAL FULLTEXT UNIQUE).each do |type|
+      expected = "CREATE TABLE `people` (#{type} INDEX `index_people_on_last_name`  (`last_name`) ) ENGINE=InnoDB"
+      actual = ActiveRecord::Base.connection.create_table(:people, id: false) do |t|
+        t.index :last_name, type: type
+      end
+      assert_equal expected, actual
+    end
+
+    expected = "CREATE TABLE `people` ( INDEX `index_people_on_last_name` USING btree (`last_name`(10)) ) ENGINE=InnoDB"
+    actual = ActiveRecord::Base.connection.create_table(:people, id: false) do |t|
+      t.index :last_name, length: 10, using: :btree
+    end
+    assert_equal expected, actual
   end
 
-  if current_adapter?(:Mysql2Adapter)
-    def test_create_mysql_database_with_encoding
-      assert_equal "CREATE DATABASE `matt` DEFAULT CHARACTER SET `utf8`", create_database(:matt)
-      assert_equal "CREATE DATABASE `aimonetti` DEFAULT CHARACTER SET `latin1`", create_database(:aimonetti, {:charset => 'latin1'})
-      assert_equal "CREATE DATABASE `matt_aimonetti` DEFAULT CHARACTER SET `big5` COLLATE `big5_chinese_ci`", create_database(:matt_aimonetti, {:charset => :big5, :collation => :big5_chinese_ci})
+  def test_index_in_bulk_change
+    def (ActiveRecord::Base.connection).table_exists?(*); true; end
+    def (ActiveRecord::Base.connection).index_name_exists?(*); false; end
+
+    %w(SPATIAL FULLTEXT UNIQUE).each do |type|
+      expected = "ALTER TABLE `people` ADD #{type} INDEX `index_people_on_last_name`  (`last_name`)"
+      actual = ActiveRecord::Base.connection.change_table(:people, bulk: true) do |t|
+        t.index :last_name, type: type
+      end
+      assert_equal expected, actual
     end
 
-    def test_recreate_mysql_database_with_encoding
-      create_database(:luca, {:charset => 'latin1'})
-      assert_equal "CREATE DATABASE `luca` DEFAULT CHARACTER SET `latin1`", recreate_database(:luca, {:charset => 'latin1'})
+    expected = "ALTER TABLE `peaple` ADD  INDEX `index_peaple_on_last_name` USING btree (`last_name`(10)), ALGORITHM = COPY"
+    actual = ActiveRecord::Base.connection.change_table(:peaple, bulk: true) do |t|
+      t.index :last_name, length: 10, using: :btree, algorithm: :copy
     end
+    assert_equal expected, actual
+  end
+
+  def test_drop_table
+    assert_equal "DROP TABLE `people`", drop_table(:people)
+  end
+
+  def test_create_mysql_database_with_encoding
+    assert_equal "CREATE DATABASE `matt` DEFAULT CHARACTER SET `utf8`", create_database(:matt)
+    assert_equal "CREATE DATABASE `aimonetti` DEFAULT CHARACTER SET `latin1`", create_database(:aimonetti, {:charset => 'latin1'})
+    assert_equal "CREATE DATABASE `matt_aimonetti` DEFAULT CHARACTER SET `big5` COLLATE `big5_chinese_ci`", create_database(:matt_aimonetti, {:charset => :big5, :collation => :big5_chinese_ci})
+  end
+
+  def test_recreate_mysql_database_with_encoding
+    create_database(:luca, {:charset => 'latin1'})
+    assert_equal "CREATE DATABASE `luca` DEFAULT CHARACTER SET `latin1`", recreate_database(:luca, {:charset => 'latin1'})
   end
 
   def test_add_column
diff --git a/activerecord/test/cases/adapters/mysql2/bind_parameter_test.rb b/activerecord/test/cases/adapters/mysql2/bind_parameter_test.rb
index 5e8065d80d..abdf3dbf5b 100644
--- a/activerecord/test/cases/adapters/mysql2/bind_parameter_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/bind_parameter_test.rb
@@ -4,7 +4,7 @@ require 'models/topic'
 module ActiveRecord
   module ConnectionAdapters
     class Mysql2Adapter
-      class BindParameterTest < ActiveRecord::TestCase
+      class BindParameterTest < ActiveRecord::Mysql2TestCase
         fixtures :topics
 
         def test_update_question_marks
diff --git a/activerecord/test/cases/adapters/mysql2/boolean_test.rb b/activerecord/test/cases/adapters/mysql2/boolean_test.rb
index 0e641ba3bf..8575df9e43 100644
--- a/activerecord/test/cases/adapters/mysql2/boolean_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/boolean_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 
-class Mysql2BooleanTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+class Mysql2BooleanTest < ActiveRecord::Mysql2TestCase
+  self.use_transactional_tests = false
 
   class BooleanType < ActiveRecord::Base
     self.table_name = "mysql_booleans"
diff --git a/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb b/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
index 09bebf3071..963116f08a 100644
--- a/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
@@ -1,7 +1,6 @@
 require "cases/helper"
-require 'models/person'
 
-class Mysql2CaseSensitivityTest < ActiveRecord::TestCase
+class Mysql2CaseSensitivityTest < ActiveRecord::Mysql2TestCase
   class CollationTest < ActiveRecord::Base
   end
 
diff --git a/activerecord/test/cases/adapters/mysql2/charset_collation_test.rb b/activerecord/test/cases/adapters/mysql2/charset_collation_test.rb
new file mode 100644
index 0000000000..4fd34def15
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql2/charset_collation_test.rb
@@ -0,0 +1,54 @@
+require "cases/helper"
+require 'support/schema_dumping_helper'
+
+class Mysql2CharsetCollationTest < ActiveRecord::Mysql2TestCase
+  include SchemaDumpingHelper
+  self.use_transactional_tests = false
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table :charset_collations, force: true do |t|
+      t.string :string_ascii_bin, charset: 'ascii', collation: 'ascii_bin'
+      t.text :text_ucs2_unicode_ci, charset: 'ucs2', collation: 'ucs2_unicode_ci'
+    end
+  end
+
+  teardown do
+    @connection.drop_table :charset_collations, if_exists: true
+  end
+
+  test "string column with charset and collation" do
+    column = @connection.columns(:charset_collations).find { |c| c.name == 'string_ascii_bin' }
+    assert_equal :string, column.type
+    assert_equal 'ascii_bin', column.collation
+  end
+
+  test "text column with charset and collation" do
+    column = @connection.columns(:charset_collations).find { |c| c.name == 'text_ucs2_unicode_ci' }
+    assert_equal :text, column.type
+    assert_equal 'ucs2_unicode_ci', column.collation
+  end
+
+  test "add column with charset and collation" do
+    @connection.add_column :charset_collations, :title, :string, charset: 'utf8', collation: 'utf8_bin'
+
+    column = @connection.columns(:charset_collations).find { |c| c.name == 'title' }
+    assert_equal :string, column.type
+    assert_equal 'utf8_bin', column.collation
+  end
+
+  test "change column with charset and collation" do
+    @connection.add_column :charset_collations, :description, :string, charset: 'utf8', collation: 'utf8_unicode_ci'
+    @connection.change_column :charset_collations, :description, :text, charset: 'utf8', collation: 'utf8_general_ci'
+
+    column = @connection.columns(:charset_collations).find { |c| c.name == 'description' }
+    assert_equal :text, column.type
+    assert_equal 'utf8_general_ci', column.collation
+  end
+
+  test "schema dump includes collation" do
+    output = dump_table_schema("charset_collations")
+    assert_match %r{t.string\s+"string_ascii_bin",\s+limit: 255,\s+collation: "ascii_bin"$}, output
+    assert_match %r{t.text\s+"text_ucs2_unicode_ci",\s+limit: 65535,\s+collation: "ucs2_unicode_ci"$}, output
+  end
+end
diff --git a/activerecord/test/cases/adapters/mysql2/connection_test.rb b/activerecord/test/cases/adapters/mysql2/connection_test.rb
index d261e2db55..000bcadebe 100644
--- a/activerecord/test/cases/adapters/mysql2/connection_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/connection_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 require 'support/connection_helper'
 
-class MysqlConnectionTest < ActiveRecord::TestCase
+class Mysql2ConnectionTest < ActiveRecord::Mysql2TestCase
   include ConnectionHelper
 
   fixtures :comments
@@ -22,7 +22,7 @@ class MysqlConnectionTest < ActiveRecord::TestCase
     assert_raise ActiveRecord::NoDatabaseError do
       configuration = ActiveRecord::Base.configurations['arunit'].merge(database: 'inexistent_activerecord_unittest')
       connection = ActiveRecord::Base.mysql2_connection(configuration)
-      connection.exec_query('drop table if exists ex')
+      connection.drop_table 'ex', if_exists: true
     end
   end
 
@@ -84,6 +84,15 @@ class MysqlConnectionTest < ActiveRecord::TestCase
     end
   end
 
+  def test_mysql_strict_mode_specified_default
+    run_without_connection do |orig_connection|
+      ActiveRecord::Base.establish_connection(orig_connection.merge({strict: :default}))
+      global_sql_mode = ActiveRecord::Base.connection.exec_query "SELECT @@GLOBAL.sql_mode"
+      session_sql_mode = ActiveRecord::Base.connection.exec_query "SELECT @@SESSION.sql_mode"
+      assert_equal global_sql_mode.rows, session_sql_mode.rows
+    end
+  end
+
   def test_mysql_set_session_variable
     run_without_connection do |orig_connection|
       ActiveRecord::Base.establish_connection(orig_connection.deep_merge({:variables => {:default_week_format => 3}}))
@@ -122,11 +131,4 @@ class MysqlConnectionTest < ActiveRecord::TestCase
   ensure
     @connection.execute "DROP TABLE `bar_baz`"
   end
-
-  if mysql_56?
-    def test_quote_time_usec
-      assert_equal "'1970-01-01 00:00:00.000000'", @connection.quote(Time.at(0))
-      assert_equal "'1970-01-01 00:00:00.000000'", @connection.quote(Time.at(0).to_datetime)
-    end
-  end
 end
diff --git a/activerecord/test/cases/adapters/mysql2/datetime_test.rb b/activerecord/test/cases/adapters/mysql2/datetime_test.rb
deleted file mode 100644
index ae00f4e131..0000000000
--- a/activerecord/test/cases/adapters/mysql2/datetime_test.rb
+++ /dev/null
@@ -1,87 +0,0 @@
-require 'cases/helper'
-
-if mysql_56?
-  class DateTimeTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
-
-    class Foo < ActiveRecord::Base; end
-
-    def test_default_datetime_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true)
-      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime
-      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime
-      assert_nil activerecord_column_option('foos', 'created_at', 'precision')
-    end
-
-    def test_datetime_data_type_with_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true)
-      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime, precision: 1
-      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime, precision: 5
-      assert_equal 1, activerecord_column_option('foos', 'created_at', 'precision')
-      assert_equal 5, activerecord_column_option('foos', 'updated_at', 'precision')
-    end
-
-    def test_timestamps_helper_with_custom_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-        t.timestamps null: true, precision: 4
-      end
-      assert_equal 4, activerecord_column_option('foos', 'created_at', 'precision')
-      assert_equal 4, activerecord_column_option('foos', 'updated_at', 'precision')
-    end
-
-    def test_passing_precision_to_datetime_does_not_set_limit
-      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-        t.timestamps null: true, precision: 4
-      end
-      assert_nil activerecord_column_option('foos', 'created_at', 'limit')
-      assert_nil activerecord_column_option('foos', 'updated_at', 'limit')
-    end
-
-    def test_invalid_datetime_precision_raises_error
-      assert_raises ActiveRecord::ActiveRecordError do
-        ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-          t.timestamps null: true, precision: 7
-        end
-      end
-    end
-
-    def test_mysql_agrees_with_activerecord_about_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-        t.timestamps null: true, precision: 4
-      end
-      assert_equal 4, mysql_datetime_precision('foos', 'created_at')
-      assert_equal 4, mysql_datetime_precision('foos', 'updated_at')
-    end
-
-    def test_formatting_datetime_according_to_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
-        t.datetime :created_at, precision: 0
-        t.datetime :updated_at, precision: 4
-      end
-      date = ::Time.utc(2014, 8, 17, 12, 30, 0, 999999)
-      Foo.create!(created_at: date, updated_at: date)
-      assert foo = Foo.find_by(created_at: date)
-      assert_equal date.to_s, foo.created_at.to_s
-      assert_equal date.to_s, foo.updated_at.to_s
-      assert_equal 000000, foo.created_at.usec
-      assert_equal 999900, foo.updated_at.usec
-    end
-
-    private
-
-    def mysql_datetime_precision(table_name, column_name)
-      results = ActiveRecord::Base.connection.exec_query("SELECT column_name, datetime_precision FROM information_schema.columns WHERE table_name = '#{table_name}'")
-      result = results.find do |result_hash|
-        result_hash["column_name"] == column_name
-      end
-      result && result["datetime_precision"]
-    end
-
-    def activerecord_column_option(tablename, column_name, option)
-      result = ActiveRecord::Base.connection.columns(tablename).find do |column|
-        column.name == column_name
-      end
-      result && result.send(option)
-    end
-  end
-end
diff --git a/activerecord/test/cases/adapters/mysql2/enum_test.rb b/activerecord/test/cases/adapters/mysql2/enum_test.rb
index 6dd9a5ec87..bd732b5eca 100644
--- a/activerecord/test/cases/adapters/mysql2/enum_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/enum_test.rb
@@ -1,6 +1,6 @@
 require "cases/helper"
 
-class Mysql2EnumTest < ActiveRecord::TestCase
+class Mysql2EnumTest < ActiveRecord::Mysql2TestCase
   class EnumTest < ActiveRecord::Base
   end
 
diff --git a/activerecord/test/cases/adapters/mysql2/explain_test.rb b/activerecord/test/cases/adapters/mysql2/explain_test.rb
index 2b01d941b8..4fc7414b18 100644
--- a/activerecord/test/cases/adapters/mysql2/explain_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/explain_test.rb
@@ -5,7 +5,7 @@ require 'models/computer'
 module ActiveRecord
   module ConnectionAdapters
     class Mysql2Adapter
-      class ExplainTest < ActiveRecord::TestCase
+      class ExplainTest < ActiveRecord::Mysql2TestCase
         fixtures :developers
 
         def test_explain_for_one_query
diff --git a/activerecord/test/cases/adapters/mysql2/json_test.rb b/activerecord/test/cases/adapters/mysql2/json_test.rb
new file mode 100644
index 0000000000..c8c933af5e
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql2/json_test.rb
@@ -0,0 +1,172 @@
+require 'cases/helper'
+require 'support/schema_dumping_helper'
+
+if ActiveRecord::Base.connection.supports_json?
+class Mysql2JSONTest < ActiveRecord::Mysql2TestCase
+  include SchemaDumpingHelper
+  self.use_transactional_tests = false
+
+  class JsonDataType < ActiveRecord::Base
+    self.table_name = 'json_data_type'
+
+    store_accessor :settings, :resolution
+  end
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+    begin
+      @connection.create_table('json_data_type') do |t|
+        t.json 'payload'
+        t.json 'settings'
+      end
+    end
+  end
+
+  def teardown
+    @connection.drop_table :json_data_type, if_exists: true
+    JsonDataType.reset_column_information
+  end
+
+  def test_column
+    column = JsonDataType.columns_hash["payload"]
+    assert_equal :json, column.type
+    assert_equal 'json', column.sql_type
+
+    type = JsonDataType.type_for_attribute("payload")
+    assert_not type.binary?
+  end
+
+  def test_change_table_supports_json
+    @connection.change_table('json_data_type') do |t|
+      t.json 'users'
+    end
+    JsonDataType.reset_column_information
+    column = JsonDataType.columns_hash['users']
+    assert_equal :json, column.type
+  end
+
+  def test_schema_dumping
+    output = dump_table_schema("json_data_type")
+    assert_match(/t\.json\s+"settings"/, output)
+  end
+
+  def test_cast_value_on_write
+    x = JsonDataType.new payload: {"string" => "foo", :symbol => :bar}
+    assert_equal({"string" => "foo", :symbol => :bar}, x.payload_before_type_cast)
+    assert_equal({"string" => "foo", "symbol" => "bar"}, x.payload)
+    x.save
+    assert_equal({"string" => "foo", "symbol" => "bar"}, x.reload.payload)
+  end
+
+  def test_type_cast_json
+    type = JsonDataType.type_for_attribute("payload")
+
+    data = "{\"a_key\":\"a_value\"}"
+    hash = type.deserialize(data)
+    assert_equal({'a_key' => 'a_value'}, hash)
+    assert_equal({'a_key' => 'a_value'}, type.deserialize(data))
+
+    assert_equal({}, type.deserialize("{}"))
+    assert_equal({'key'=>nil}, type.deserialize('{"key": null}'))
+    assert_equal({'c'=>'}','"a"'=>'b "a b'}, type.deserialize(%q({"c":"}", "\"a\"":"b \"a b"})))
+  end
+
+  def test_rewrite
+    @connection.execute "insert into json_data_type (payload) VALUES ('{\"k\":\"v\"}')"
+    x = JsonDataType.first
+    x.payload = { '"a\'' => 'b' }
+    assert x.save!
+  end
+
+  def test_select
+    @connection.execute "insert into json_data_type (payload) VALUES ('{\"k\":\"v\"}')"
+    x = JsonDataType.first
+    assert_equal({'k' => 'v'}, x.payload)
+  end
+
+  def test_select_multikey
+    @connection.execute %q|insert into json_data_type (payload) VALUES ('{"k1":"v1", "k2":"v2", "k3":[1,2,3]}')|
+    x = JsonDataType.first
+    assert_equal({'k1' => 'v1', 'k2' => 'v2', 'k3' => [1,2,3]}, x.payload)
+  end
+
+  def test_null_json
+    @connection.execute %q|insert into json_data_type (payload) VALUES(null)|
+    x = JsonDataType.first
+    assert_equal(nil, x.payload)
+  end
+
+  def test_select_array_json_value
+    @connection.execute %q|insert into json_data_type (payload) VALUES ('["v0",{"k1":"v1"}]')|
+    x = JsonDataType.first
+    assert_equal(['v0', {'k1' => 'v1'}], x.payload)
+  end
+
+  def test_rewrite_array_json_value
+    @connection.execute %q|insert into json_data_type (payload) VALUES ('["v0",{"k1":"v1"}]')|
+    x = JsonDataType.first
+    x.payload = ['v1', {'k2' => 'v2'}, 'v3']
+    assert x.save!
+  end
+
+  def test_with_store_accessors
+    x = JsonDataType.new(resolution: "320×480")
+    assert_equal "320×480", x.resolution
+
+    x.save!
+    x = JsonDataType.first
+    assert_equal "320×480", x.resolution
+
+    x.resolution = "640×1136"
+    x.save!
+
+    x = JsonDataType.first
+    assert_equal "640×1136", x.resolution
+  end
+
+  def test_duplication_with_store_accessors
+    x = JsonDataType.new(resolution: "320×480")
+    assert_equal "320×480", x.resolution
+
+    y = x.dup
+    assert_equal "320×480", y.resolution
+  end
+
+  def test_yaml_round_trip_with_store_accessors
+    x = JsonDataType.new(resolution: "320×480")
+    assert_equal "320×480", x.resolution
+
+    y = YAML.load(YAML.dump(x))
+    assert_equal "320×480", y.resolution
+  end
+
+  def test_changes_in_place
+    json = JsonDataType.new
+    assert_not json.changed?
+
+    json.payload = { 'one' => 'two' }
+    assert json.changed?
+    assert json.payload_changed?
+
+    json.save!
+    assert_not json.changed?
+
+    json.payload['three'] = 'four'
+    assert json.payload_changed?
+
+    json.save!
+    json.reload
+
+    assert_equal({ 'one' => 'two', 'three' => 'four' }, json.payload)
+    assert_not json.changed?
+  end
+
+  def test_assigning_invalid_json
+    json = JsonDataType.new
+
+    json.payload = 'foo'
+
+    assert_nil json.payload
+  end
+end
+end
diff --git a/activerecord/test/cases/adapters/mysql2/quoting_test.rb b/activerecord/test/cases/adapters/mysql2/quoting_test.rb
new file mode 100644
index 0000000000..2de7e1b526
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql2/quoting_test.rb
@@ -0,0 +1,21 @@
+require "cases/helper"
+
+class Mysql2QuotingTest < ActiveRecord::Mysql2TestCase
+  setup do
+    @connection = ActiveRecord::Base.connection
+  end
+
+  test 'quoted date precision for gte 5.6.4' do
+    @connection.stubs(:full_version).returns('5.6.4')
+    @connection.remove_instance_variable(:@version) if @connection.instance_variable_defined?(:@version)
+    t = Time.now.change(usec: 1)
+    assert_match(/\.000001\z/, @connection.quoted_date(t))
+  end
+
+  test 'quoted date precision for lt 5.6.4' do
+    @connection.stubs(:full_version).returns('5.6.3')
+    @connection.remove_instance_variable(:@version) if @connection.instance_variable_defined?(:@version)
+    t = Time.now.change(usec: 1)
+    assert_no_match(/\.000001\z/, @connection.quoted_date(t))
+  end
+end
diff --git a/activerecord/test/cases/adapters/mysql2/reserved_word_test.rb b/activerecord/test/cases/adapters/mysql2/reserved_word_test.rb
index 7f97b454bb..ffb4e2c5cf 100644
--- a/activerecord/test/cases/adapters/mysql2/reserved_word_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/reserved_word_test.rb
@@ -1,29 +1,29 @@
 require "cases/helper"
 
-class Group < ActiveRecord::Base
-  Group.table_name = 'group'
-  belongs_to :select
-  has_one :values
-end
+# a suite of tests to ensure the ConnectionAdapters#MysqlAdapter can handle tables with
+# reserved word names (ie: group, order, values, etc...)
+class Mysql2ReservedWordTest < ActiveRecord::Mysql2TestCase
+  class Group < ActiveRecord::Base
+    Group.table_name = 'group'
+    belongs_to :select
+    has_one :values
+  end
 
-class Select < ActiveRecord::Base
-  Select.table_name = 'select'
-  has_many :groups
-end
+  class Select < ActiveRecord::Base
+    Select.table_name = 'select'
+    has_many :groups
+  end
 
-class Values < ActiveRecord::Base
-  Values.table_name = 'values'
-end
+  class Values < ActiveRecord::Base
+    Values.table_name = 'values'
+  end
 
-class Distinct < ActiveRecord::Base
-  Distinct.table_name = 'distinct'
-  has_and_belongs_to_many :selects
-  has_many :values, :through => :groups
-end
+  class Distinct < ActiveRecord::Base
+    Distinct.table_name = 'distinct'
+    has_and_belongs_to_many :selects
+    has_many :values, :through => :groups
+  end
 
-# a suite of tests to ensure the ConnectionAdapters#MysqlAdapter can handle tables with
-# reserved word names (ie: group, order, values, etc...)
-class MysqlReservedWordTest < ActiveRecord::TestCase
   def setup
     @connection = ActiveRecord::Base.connection
 
@@ -71,7 +71,7 @@ class MysqlReservedWordTest < ActiveRecord::TestCase
 
   #fixtures
   self.use_instantiated_fixtures = true
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   #activerecord model class with reserved-word table name
   def test_activerecord_model
@@ -138,7 +138,7 @@ class MysqlReservedWordTest < ActiveRecord::TestCase
   # custom drop table, uses execute on connection to drop a table if it exists. note: escapes table_name
   def drop_tables_directly(table_names, connection = @connection)
     table_names.each do |name|
-      connection.execute("DROP TABLE IF EXISTS `#{name}`")
+      connection.drop_table name, if_exists: true
     end
   end
 
diff --git a/activerecord/test/cases/adapters/mysql2/schema_migrations_test.rb b/activerecord/test/cases/adapters/mysql2/schema_migrations_test.rb
index 9c49599d34..396f235e77 100644
--- a/activerecord/test/cases/adapters/mysql2/schema_migrations_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/schema_migrations_test.rb
@@ -1,39 +1,42 @@
 require "cases/helper"
 
-module ActiveRecord
-  module ConnectionAdapters
-    class Mysql2Adapter
-      class SchemaMigrationsTest < ActiveRecord::TestCase
-        def test_renaming_index_on_foreign_key
-          connection.add_index "engines", "car_id"
-          connection.add_foreign_key :engines, :cars, name: "fk_engines_cars"
-
-          connection.rename_index("engines", "index_engines_on_car_id", "idx_renamed")
-          assert_equal ["idx_renamed"], connection.indexes("engines").map(&:name)
-        ensure
-          connection.remove_foreign_key :engines, name: "fk_engines_cars"
-        end
-
-        def test_initializes_schema_migrations_for_encoding_utf8mb4
-          smtn = ActiveRecord::Migrator.schema_migrations_table_name
-          connection.drop_table(smtn) if connection.table_exists?(smtn)
-
-          config = connection.instance_variable_get(:@config)
-          original_encoding = config[:encoding]
-
-          config[:encoding] = 'utf8mb4'
-          connection.initialize_schema_migrations_table
-
-          assert connection.column_exists?(smtn, :version, :string, limit: Mysql2Adapter::MAX_INDEX_LENGTH_FOR_UTF8MB4)
-        ensure
-          config[:encoding] = original_encoding
-        end
-
-        private
-        def connection
-          @connection ||= ActiveRecord::Base.connection
-        end
-      end
-    end
+class SchemaMigrationsTest < ActiveRecord::Mysql2TestCase
+  def test_renaming_index_on_foreign_key
+    connection.add_index "engines", "car_id"
+    connection.add_foreign_key :engines, :cars, name: "fk_engines_cars"
+
+    connection.rename_index("engines", "index_engines_on_car_id", "idx_renamed")
+    assert_equal ["idx_renamed"], connection.indexes("engines").map(&:name)
+  ensure
+    connection.remove_foreign_key :engines, name: "fk_engines_cars"
+  end
+
+  def test_initializes_schema_migrations_for_encoding_utf8mb4
+    smtn = ActiveRecord::Migrator.schema_migrations_table_name
+    connection.drop_table smtn, if_exists: true
+
+    database_name = connection.current_database
+    database_info = connection.select_one("SELECT * FROM information_schema.schemata WHERE schema_name = '#{database_name}'")
+
+    original_charset = database_info["DEFAULT_CHARACTER_SET_NAME"]
+    original_collation = database_info["DEFAULT_COLLATION_NAME"]
+
+    execute("ALTER DATABASE #{database_name} DEFAULT CHARACTER SET utf8mb4")
+
+    connection.initialize_schema_migrations_table
+
+    limit = ActiveRecord::ConnectionAdapters::AbstractMysqlAdapter::MAX_INDEX_LENGTH_FOR_CHARSETS_OF_4BYTES_MAXLEN
+    assert connection.column_exists?(smtn, :version, :string, limit: limit)
+  ensure
+    execute("ALTER DATABASE #{database_name} DEFAULT CHARACTER SET #{original_charset} COLLATE #{original_collation}")
+  end
+
+  private
+  def connection
+    @connection ||= ActiveRecord::Base.connection
+  end
+
+  def execute(sql)
+    connection.execute(sql)
   end
 end
diff --git a/activerecord/test/cases/adapters/mysql2/schema_test.rb b/activerecord/test/cases/adapters/mysql2/schema_test.rb
index 47707b7d4f..faf2acb9cb 100644
--- a/activerecord/test/cases/adapters/mysql2/schema_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/schema_test.rb
@@ -4,7 +4,7 @@ require 'models/comment'
 
 module ActiveRecord
   module ConnectionAdapters
-    class Mysql2SchemaTest < ActiveRecord::TestCase
+    class Mysql2SchemaTest < ActiveRecord::Mysql2TestCase
       fixtures :posts
 
       def setup
@@ -36,14 +36,6 @@ module ActiveRecord
         assert(!@connection.table_exists?("#{@db_name}.zomg"), "table should not exist")
       end
 
-      def test_tables_quoting
-        @connection.tables(nil, "foo-bar", nil)
-        flunk
-      rescue => e
-        # assertion for *quoted* database properly
-        assert_match(/database 'foo-bar'/, e.inspect)
-      end
-
       def test_dump_indexes
         index_a_name = 'index_key_tests_on_snack'
         index_b_name = 'index_key_tests_on_pizza'
diff --git a/activerecord/test/cases/adapters/mysql2/sp_test.rb b/activerecord/test/cases/adapters/mysql2/sp_test.rb
new file mode 100644
index 0000000000..8b12945f24
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql2/sp_test.rb
@@ -0,0 +1,29 @@
+require "cases/helper"
+require 'models/topic'
+require 'models/reply'
+
+class Mysql2StoredProcedureTest < ActiveRecord::Mysql2TestCase
+  fixtures :topics
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+  end
+
+  # Test that MySQL allows multiple results for stored procedures
+  #
+  # In MySQL 5.6, CLIENT_MULTI_RESULTS is enabled by default.
+  # http://dev.mysql.com/doc/refman/5.6/en/call.html
+  if ActiveRecord::Base.connection.version >= '5.6.0'
+    def test_multi_results
+      rows = @connection.select_rows('CALL ten();')
+      assert_equal 10, rows[0][0].to_i, "ten() did not return 10 as expected: #{rows.inspect}"
+      assert @connection.active?, "Bad connection use by 'Mysql2Adapter.select_rows'"
+    end
+
+    def test_multi_results_from_find_by_sql
+      topics = Topic.find_by_sql 'CALL topics(3);'
+      assert_equal 3, topics.size
+      assert @connection.active?, "Bad connection use by 'Mysql2Adapter.select'"
+    end
+  end
+end
diff --git a/activerecord/test/cases/adapters/mysql2/sql_types_test.rb b/activerecord/test/cases/adapters/mysql2/sql_types_test.rb
index 1ddb1b91c9..4926bc2267 100644
--- a/activerecord/test/cases/adapters/mysql2/sql_types_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/sql_types_test.rb
@@ -1,10 +1,10 @@
 require "cases/helper"
 
-class SqlTypesTest < ActiveRecord::TestCase
+class Mysql2SqlTypesTest < ActiveRecord::Mysql2TestCase
   def test_binary_types
     assert_equal 'varbinary(64)', type_to_sql(:binary, 64)
     assert_equal 'varbinary(4095)', type_to_sql(:binary, 4095)
-    assert_equal 'blob(4096)', type_to_sql(:binary, 4096)
+    assert_equal 'blob', type_to_sql(:binary, 4096)
     assert_equal 'blob', type_to_sql(:binary)
   end
 
diff --git a/activerecord/test/cases/adapters/mysql2/table_options_test.rb b/activerecord/test/cases/adapters/mysql2/table_options_test.rb
new file mode 100644
index 0000000000..af121ee7d9
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql2/table_options_test.rb
@@ -0,0 +1,42 @@
+require "cases/helper"
+require 'support/schema_dumping_helper'
+
+class Mysql2TableOptionsTest < ActiveRecord::Mysql2TestCase
+  include SchemaDumpingHelper
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+  end
+
+  def teardown
+    @connection.drop_table "mysql_table_options", if_exists: true
+  end
+
+  test "table options with ENGINE" do
+    @connection.create_table "mysql_table_options", force: true, options: "ENGINE=MyISAM"
+    output = dump_table_schema("mysql_table_options")
+    options = %r{create_table "mysql_table_options", force: :cascade, options: "(?<options>.*)"}.match(output)[:options]
+    assert_match %r{ENGINE=MyISAM}, options
+  end
+
+  test "table options with ROW_FORMAT" do
+    @connection.create_table "mysql_table_options", force: true, options: "ROW_FORMAT=REDUNDANT"
+    output = dump_table_schema("mysql_table_options")
+    options = %r{create_table "mysql_table_options", force: :cascade, options: "(?<options>.*)"}.match(output)[:options]
+    assert_match %r{ROW_FORMAT=REDUNDANT}, options
+  end
+
+  test "table options with CHARSET" do
+    @connection.create_table "mysql_table_options", force: true, options: "CHARSET=utf8mb4"
+    output = dump_table_schema("mysql_table_options")
+    options = %r{create_table "mysql_table_options", force: :cascade, options: "(?<options>.*)"}.match(output)[:options]
+    assert_match %r{CHARSET=utf8mb4}, options
+  end
+
+  test "table options with COLLATE" do
+    @connection.create_table "mysql_table_options", force: true, options: "COLLATE=utf8mb4_bin"
+    output = dump_table_schema("mysql_table_options")
+    options = %r{create_table "mysql_table_options", force: :cascade, options: "(?<options>.*)"}.match(output)[:options]
+    assert_match %r{COLLATE=utf8mb4_bin}, options
+  end
+end
diff --git a/activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb b/activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb
index 8f521e9181..a6f6dd21bb 100644
--- a/activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb
@@ -1,7 +1,9 @@
 require "cases/helper"
+require "support/schema_dumping_helper"
 
-class UnsignedTypeTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+class Mysql2UnsignedTypeTest < ActiveRecord::Mysql2TestCase
+  include SchemaDumpingHelper
+  self.use_transactional_tests = false
 
   class UnsignedType < ActiveRecord::Base
   end
@@ -9,12 +11,15 @@ class UnsignedTypeTest < ActiveRecord::TestCase
   setup do
     @connection = ActiveRecord::Base.connection
     @connection.create_table("unsigned_types", force: true) do |t|
-      t.column :unsigned_integer, "int unsigned"
+      t.integer :unsigned_integer, unsigned: true
+      t.bigint  :unsigned_bigint,  unsigned: true
+      t.float   :unsigned_float,   unsigned: true
+      t.decimal :unsigned_decimal, unsigned: true, precision: 10, scale: 2
     end
   end
 
   teardown do
-    @connection.drop_table "unsigned_types"
+    @connection.drop_table "unsigned_types", if_exists: true
   end
 
   test "unsigned int max value is in range" do
@@ -26,5 +31,35 @@ class UnsignedTypeTest < ActiveRecord::TestCase
     assert_raise(RangeError) do
       UnsignedType.create(unsigned_integer: -10)
     end
+    assert_raise(RangeError) do
+      UnsignedType.create(unsigned_bigint: -10)
+    end
+    assert_raise(ActiveRecord::StatementInvalid) do
+      UnsignedType.create(unsigned_float: -10.0)
+    end
+    assert_raise(ActiveRecord::StatementInvalid) do
+      UnsignedType.create(unsigned_decimal: -10.0)
+    end
+  end
+
+  test "schema definition can use unsigned as the type" do
+    @connection.change_table("unsigned_types") do |t|
+      t.unsigned_integer :unsigned_integer_t
+      t.unsigned_bigint  :unsigned_bigint_t
+      t.unsigned_float   :unsigned_float_t
+      t.unsigned_decimal :unsigned_decimal_t, precision: 10, scale: 2
+    end
+
+    @connection.columns("unsigned_types").select { |c| /^unsigned_/ === c.name }.each do |column|
+      assert column.unsigned?
+    end
+  end
+
+  test "schema dump includes unsigned option" do
+    schema = dump_table_schema "unsigned_types"
+    assert_match %r{t.integer\s+"unsigned_integer",\s+limit: 4,\s+unsigned: true$}, schema
+    assert_match %r{t.integer\s+"unsigned_bigint",\s+limit: 8,\s+unsigned: true$}, schema
+    assert_match %r{t.float\s+"unsigned_float",\s+limit: 24,\s+unsigned: true$}, schema
+    assert_match %r{t.decimal\s+"unsigned_decimal",\s+precision: 10,\s+scale: 2,\s+unsigned: true$}, schema
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
index 3808db5141..24def31e36 100644
--- a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
@@ -1,6 +1,6 @@
 require 'cases/helper'
 
-class PostgresqlActiveSchemaTest < ActiveRecord::TestCase
+class PostgresqlActiveSchemaTest < ActiveRecord::PostgreSQLTestCase
   def setup
     ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.class_eval do
       def execute(sql, name = nil) sql end
@@ -25,7 +25,7 @@ class PostgresqlActiveSchemaTest < ActiveRecord::TestCase
 
   def test_add_index
     # add_index calls index_name_exists? which can't work since execute is stubbed
-    ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.stubs(:index_name_exists?).returns(false)
+    ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.send(:define_method, :index_name_exists?) { |*| false }
 
     expected = %(CREATE UNIQUE INDEX  "index_people_on_last_name" ON "people"  ("last_name") WHERE state = 'active')
     assert_equal expected, add_index(:people, :last_name, :unique => true, :where => "state = 'active'")
@@ -49,6 +49,22 @@ class PostgresqlActiveSchemaTest < ActiveRecord::TestCase
 
     expected = %(CREATE UNIQUE INDEX  "index_people_on_last_name" ON "people" USING gist ("last_name") WHERE state = 'active')
     assert_equal expected, add_index(:people, :last_name, :unique => true, :where => "state = 'active'", :using => :gist)
+
+    ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.send :remove_method, :index_name_exists?
+  end
+
+  def test_remove_index
+    # remove_index calls index_name_exists? which can't work since execute is stubbed
+    ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.send(:define_method, :index_name_exists?) { |*| true }
+
+    expected = %(DROP INDEX CONCURRENTLY "index_people_on_last_name")
+    assert_equal expected, remove_index(:people, name: "index_people_on_last_name", algorithm: :concurrently)
+
+    assert_raise ArgumentError do
+      add_index(:people, :last_name, algorithm: :copy)
+    end
+
+    ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.send :remove_method, :index_name_exists?
   end
 
   private
diff --git a/activerecord/test/cases/adapters/postgresql/array_test.rb b/activerecord/test/cases/adapters/postgresql/array_test.rb
index 77055f5b7a..380a90d765 100644
--- a/activerecord/test/cases/adapters/postgresql/array_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/array_test.rb
@@ -1,11 +1,9 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
-class PostgresqlArrayTest < ActiveRecord::TestCase
+class PostgresqlArrayTest < ActiveRecord::PostgreSQLTestCase
   include SchemaDumpingHelper
   include InTimeZone
-  OID = ActiveRecord::ConnectionAdapters::PostgreSQL::OID
 
   class PgArray < ActiveRecord::Base
     self.table_name = 'pg_arrays'
@@ -24,11 +22,13 @@ class PostgresqlArrayTest < ActiveRecord::TestCase
         t.hstore :hstores, array: true
       end
     end
+    PgArray.reset_column_information
     @column = PgArray.columns_hash['tags']
+    @type = PgArray.type_for_attribute("tags")
   end
 
   teardown do
-    @connection.execute 'drop table if exists pg_arrays'
+    @connection.drop_table 'pg_arrays', if_exists: true
     disable_extension!('hstore', @connection)
   end
 
@@ -36,13 +36,11 @@ class PostgresqlArrayTest < ActiveRecord::TestCase
     assert_equal :string, @column.type
     assert_equal "character varying", @column.sql_type
     assert @column.array?
-    assert_not @column.number?
-    assert_not @column.binary?
+    assert_not @type.binary?
 
     ratings_column = PgArray.columns_hash['ratings']
     assert_equal :integer, ratings_column.type
     assert ratings_column.array?
-    assert_not ratings_column.number?
   end
 
   def test_default
@@ -94,9 +92,9 @@ class PostgresqlArrayTest < ActiveRecord::TestCase
   end
 
   def test_type_cast_array
-    assert_equal(['1', '2', '3'], @column.type_cast_from_database('{1,2,3}'))
-    assert_equal([], @column.type_cast_from_database('{}'))
-    assert_equal([nil], @column.type_cast_from_database('{NULL}'))
+    assert_equal(['1', '2', '3'], @type.deserialize('{1,2,3}'))
+    assert_equal([], @type.deserialize('{}'))
+    assert_equal([nil], @type.deserialize('{NULL}'))
   end
 
   def test_type_cast_integers
@@ -112,8 +110,8 @@ class PostgresqlArrayTest < ActiveRecord::TestCase
 
   def test_schema_dump_with_shorthand
     output = dump_table_schema "pg_arrays"
-    assert_match %r[t.string\s+"tags",\s+array: true], output
-    assert_match %r[t.integer\s+"ratings",\s+array: true], output
+    assert_match %r[t\.string\s+"tags",\s+array: true], output
+    assert_match %r[t\.integer\s+"ratings",\s+array: true], output
   end
 
   def test_select_with_strings
@@ -208,16 +206,17 @@ class PostgresqlArrayTest < ActiveRecord::TestCase
     x = PgArray.create!(tags: tags)
     x.reload
 
-    assert_equal x.tags_before_type_cast, PgArray.columns_hash['tags'].type_cast_for_database(tags)
+    assert_equal x.tags_before_type_cast, PgArray.type_for_attribute('tags').serialize(tags)
   end
 
   def test_quoting_non_standard_delimiters
     strings = ["hello,", "world;"]
-    comma_delim = OID::Array.new(ActiveRecord::Type::String.new, ',')
-    semicolon_delim = OID::Array.new(ActiveRecord::Type::String.new, ';')
+    oid = ActiveRecord::ConnectionAdapters::PostgreSQL::OID
+    comma_delim = oid::Array.new(ActiveRecord::Type::String.new, ',')
+    semicolon_delim = oid::Array.new(ActiveRecord::Type::String.new, ';')
 
-    assert_equal %({"hello,",world;}), comma_delim.type_cast_for_database(strings)
-    assert_equal %({hello,;"world;"}), semicolon_delim.type_cast_for_database(strings)
+    assert_equal %({"hello,",world;}), comma_delim.serialize(strings)
+    assert_equal %({hello,;"world;"}), semicolon_delim.serialize(strings)
   end
 
   def test_mutate_array
diff --git a/activerecord/test/cases/adapters/postgresql/bit_string_test.rb b/activerecord/test/cases/adapters/postgresql/bit_string_test.rb
index f154ba4cdc..6f72fa6e0f 100644
--- a/activerecord/test/cases/adapters/postgresql/bit_string_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/bit_string_test.rb
@@ -1,9 +1,8 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 require 'support/schema_dumping_helper'
 
-class PostgresqlBitStringTest < ActiveRecord::TestCase
+class PostgresqlBitStringTest < ActiveRecord::PostgreSQLTestCase
   include ConnectionHelper
   include SchemaDumpingHelper
 
@@ -14,30 +13,34 @@ class PostgresqlBitStringTest < ActiveRecord::TestCase
     @connection.create_table('postgresql_bit_strings', :force => true) do |t|
       t.bit :a_bit, default: "00000011", limit: 8
       t.bit_varying :a_bit_varying, default: "0011", limit: 4
+      t.bit :another_bit
+      t.bit_varying :another_bit_varying
     end
   end
 
   def teardown
     return unless @connection
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_bit_strings'
+    @connection.drop_table 'postgresql_bit_strings', if_exists: true
   end
 
   def test_bit_string_column
     column = PostgresqlBitString.columns_hash["a_bit"]
     assert_equal :bit, column.type
     assert_equal "bit(8)", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlBitString.type_for_attribute("a_bit")
+    assert_not type.binary?
   end
 
   def test_bit_string_varying_column
     column = PostgresqlBitString.columns_hash["a_bit_varying"]
     assert_equal :bit_varying, column.type
     assert_equal "bit varying(4)", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlBitString.type_for_attribute("a_bit_varying")
+    assert_not type.binary?
   end
 
   def test_default
diff --git a/activerecord/test/cases/adapters/postgresql/bytea_test.rb b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
index aeebec034d..b6bb1929e6 100644
--- a/activerecord/test/cases/adapters/postgresql/bytea_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
@@ -1,7 +1,6 @@
-# encoding: utf-8
 require "cases/helper"
 
-class PostgresqlByteaTest < ActiveRecord::TestCase
+class PostgresqlByteaTest < ActiveRecord::PostgreSQLTestCase
   class ByteaDataType < ActiveRecord::Base
     self.table_name = 'bytea_data_type'
   end
@@ -17,10 +16,11 @@ class PostgresqlByteaTest < ActiveRecord::TestCase
       end
     end
     @column = ByteaDataType.columns_hash['payload']
+    @type = ByteaDataType.type_for_attribute("payload")
   end
 
   teardown do
-    @connection.execute 'drop table if exists bytea_data_type'
+    @connection.drop_table 'bytea_data_type', if_exists: true
   end
 
   def test_column
@@ -40,16 +40,16 @@ class PostgresqlByteaTest < ActiveRecord::TestCase
 
     data = "\u001F\x8B"
     assert_equal('UTF-8', data.encoding.name)
-    assert_equal('ASCII-8BIT', @column.type_cast_from_database(data).encoding.name)
+    assert_equal('ASCII-8BIT', @type.deserialize(data).encoding.name)
   end
 
   def test_type_cast_binary_value
     data = "\u001F\x8B".force_encoding("BINARY")
-    assert_equal(data, @column.type_cast_from_database(data))
+    assert_equal(data, @type.deserialize(data))
   end
 
   def test_type_case_nil
-    assert_equal(nil, @column.type_cast_from_database(nil))
+    assert_equal(nil, @type.deserialize(nil))
   end
 
   def test_read_value
diff --git a/activerecord/test/cases/adapters/postgresql/change_schema_test.rb b/activerecord/test/cases/adapters/postgresql/change_schema_test.rb
index 6c1b29f7fe..bc12df668d 100644
--- a/activerecord/test/cases/adapters/postgresql/change_schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/change_schema_test.rb
@@ -2,7 +2,7 @@ require 'cases/helper'
 
 module ActiveRecord
   class Migration
-    class PGChangeSchemaTest < ActiveRecord::TestCase
+    class PGChangeSchemaTest < ActiveRecord::PostgreSQLTestCase
       attr_reader :connection
 
       def setup
@@ -26,6 +26,13 @@ module ActiveRecord
         connection.change_column :strings, :somedate, :timestamp, cast_as: :timestamp
         assert_equal :datetime, connection.columns(:strings).find { |c| c.name == 'somedate' }.type
       end
+
+      def test_change_type_with_array
+        connection.change_column :strings, :somedate, :timestamp, array: true, cast_as: :timestamp
+        column = connection.columns(:strings).find { |c| c.name == 'somedate' }
+        assert_equal :datetime, column.type
+        assert column.array?
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/cidr_test.rb b/activerecord/test/cases/adapters/postgresql/cidr_test.rb
index 54b679d3ab..52f2a0096c 100644
--- a/activerecord/test/cases/adapters/postgresql/cidr_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/cidr_test.rb
@@ -3,21 +3,21 @@ require "ipaddr"
 
 module ActiveRecord
   module ConnectionAdapters
-    class PostgreSQLAdapter
-      class CidrTest < ActiveRecord::TestCase
+    class PostgreSQLAdapter < AbstractAdapter
+      class CidrTest < ActiveRecord::PostgreSQLTestCase
         test "type casting IPAddr for database" do
           type = OID::Cidr.new
           ip = IPAddr.new("255.0.0.0/8")
           ip2 = IPAddr.new("127.0.0.1")
 
-          assert_equal "255.0.0.0/8", type.type_cast_for_database(ip)
-          assert_equal "127.0.0.1/32", type.type_cast_for_database(ip2)
+          assert_equal "255.0.0.0/8", type.serialize(ip)
+          assert_equal "127.0.0.1/32", type.serialize(ip2)
         end
 
         test "casting does nothing with non-IPAddr objects" do
           type = OID::Cidr.new
 
-          assert_equal "foo", type.type_cast_for_database("foo")
+          assert_equal "foo", type.serialize("foo")
         end
       end
     end
diff --git a/activerecord/test/cases/adapters/postgresql/citext_test.rb b/activerecord/test/cases/adapters/postgresql/citext_test.rb
index 5a8083f7a7..bd62041e79 100644
--- a/activerecord/test/cases/adapters/postgresql/citext_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/citext_test.rb
@@ -1,9 +1,8 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'support/schema_dumping_helper'
 
 if ActiveRecord::Base.connection.supports_extensions?
-  class PostgresqlCitextTest < ActiveRecord::TestCase
+  class PostgresqlCitextTest < ActiveRecord::PostgreSQLTestCase
     include SchemaDumpingHelper
     class Citext < ActiveRecord::Base
       self.table_name = 'citexts'
@@ -20,7 +19,7 @@ if ActiveRecord::Base.connection.supports_extensions?
     end
 
     teardown do
-      @connection.execute 'DROP TABLE IF EXISTS citexts;'
+      @connection.drop_table 'citexts', if_exists: true
       disable_extension!('citext', @connection)
     end
 
@@ -32,9 +31,10 @@ if ActiveRecord::Base.connection.supports_extensions?
       column = Citext.columns_hash['cival']
       assert_equal :citext, column.type
       assert_equal 'citext', column.sql_type
-      assert_not column.number?
-      assert_not column.binary?
       assert_not column.array?
+
+      type = Citext.type_for_attribute('cival')
+      assert_not type.binary?
     end
 
     def test_change_table_supports_json
@@ -72,7 +72,7 @@ if ActiveRecord::Base.connection.supports_extensions?
 
     def test_schema_dump_with_shorthand
       output = dump_table_schema("citexts")
-      assert_match %r[t.citext "cival"], output
+      assert_match %r[t\.citext "cival"], output
     end
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/collation_test.rb b/activerecord/test/cases/adapters/postgresql/collation_test.rb
new file mode 100644
index 0000000000..8470329c35
--- /dev/null
+++ b/activerecord/test/cases/adapters/postgresql/collation_test.rb
@@ -0,0 +1,53 @@
+require "cases/helper"
+require 'support/schema_dumping_helper'
+
+class PostgresqlCollationTest < ActiveRecord::PostgreSQLTestCase
+  include SchemaDumpingHelper
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table :postgresql_collations, force: true do |t|
+      t.string :string_c, collation: 'C'
+      t.text :text_posix, collation: 'POSIX'
+    end
+  end
+
+  def teardown
+    @connection.drop_table :postgresql_collations, if_exists: true
+  end
+
+  test "string column with collation" do
+    column = @connection.columns(:postgresql_collations).find { |c| c.name == 'string_c' }
+    assert_equal :string, column.type
+    assert_equal 'C', column.collation
+  end
+
+  test "text column with collation" do
+    column = @connection.columns(:postgresql_collations).find { |c| c.name == 'text_posix' }
+    assert_equal :text, column.type
+    assert_equal 'POSIX', column.collation
+  end
+
+  test "add column with collation" do
+    @connection.add_column :postgresql_collations, :title, :string, collation: 'C'
+
+    column = @connection.columns(:postgresql_collations).find { |c| c.name == 'title' }
+    assert_equal :string, column.type
+    assert_equal 'C', column.collation
+  end
+
+  test "change column with collation" do
+    @connection.add_column :postgresql_collations, :description, :string
+    @connection.change_column :postgresql_collations, :description, :text, collation: 'POSIX'
+
+    column = @connection.columns(:postgresql_collations).find { |c| c.name == 'description' }
+    assert_equal :text, column.type
+    assert_equal 'POSIX', column.collation
+  end
+
+  test "schema dump includes collation" do
+    output = dump_table_schema("postgresql_collations")
+    assert_match %r{t.string\s+"string_c",\s+collation: "C"$}, output
+    assert_match %r{t.text\s+"text_posix",\s+collation: "POSIX"$}, output
+  end
+end
diff --git a/activerecord/test/cases/adapters/postgresql/composite_test.rb b/activerecord/test/cases/adapters/postgresql/composite_test.rb
index 24c1969dee..1de87e5f01 100644
--- a/activerecord/test/cases/adapters/postgresql/composite_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/composite_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 
@@ -30,7 +29,7 @@ module PostgresqlCompositeBehavior
   def teardown
     super
 
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_composites'
+    @connection.drop_table 'postgresql_composites', if_exists: true
     @connection.execute 'DROP TYPE IF EXISTS full_address'
     reset_connection
     PostgresqlComposite.reset_column_information
@@ -41,7 +40,7 @@ end
 #   "unknown OID 5653508: failed to recognize type of 'address'. It will be treated as String."
 # To take full advantage of composite types, we suggest you register your own +OID::Type+.
 # See PostgresqlCompositeWithCustomOIDTest
-class PostgresqlCompositeTest < ActiveRecord::TestCase
+class PostgresqlCompositeTest < ActiveRecord::PostgreSQLTestCase
   include PostgresqlCompositeBehavior
 
   def test_column
@@ -50,9 +49,10 @@ class PostgresqlCompositeTest < ActiveRecord::TestCase
     column = PostgresqlComposite.columns_hash["address"]
     assert_nil column.type
     assert_equal "full_address", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlComposite.type_for_attribute("address")
+    assert_not type.binary?
   end
 
   def test_composite_mapping
@@ -77,23 +77,23 @@ class PostgresqlCompositeTest < ActiveRecord::TestCase
   end
 end
 
-class PostgresqlCompositeWithCustomOIDTest < ActiveRecord::TestCase
+class PostgresqlCompositeWithCustomOIDTest < ActiveRecord::PostgreSQLTestCase
   include PostgresqlCompositeBehavior
 
   class FullAddressType < ActiveRecord::Type::Value
     def type; :full_address end
 
-    def type_cast_from_database(value)
+    def deserialize(value)
       if value =~ /\("?([^",]*)"?,"?([^",]*)"?\)/
         FullAddress.new($1, $2)
       end
     end
 
-    def type_cast_from_user(value)
+    def cast(value)
       value
     end
 
-    def type_cast_for_database(value)
+    def serialize(value)
       return if value.nil?
       "(#{value.city},#{value.street})"
     end
@@ -111,9 +111,10 @@ class PostgresqlCompositeWithCustomOIDTest < ActiveRecord::TestCase
     column = PostgresqlComposite.columns_hash["address"]
     assert_equal :full_address, column.type
     assert_equal "full_address", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlComposite.type_for_attribute("address")
+    assert_not type.binary?
   end
 
   def test_composite_mapping
diff --git a/activerecord/test/cases/adapters/postgresql/connection_test.rb b/activerecord/test/cases/adapters/postgresql/connection_test.rb
index ab7fd3c6d5..722e2377c1 100644
--- a/activerecord/test/cases/adapters/postgresql/connection_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/connection_test.rb
@@ -2,7 +2,7 @@ require "cases/helper"
 require 'support/connection_helper'
 
 module ActiveRecord
-  class PostgresqlConnectionTest < ActiveRecord::TestCase
+  class PostgresqlConnectionTest < ActiveRecord::PostgreSQLTestCase
     include ConnectionHelper
 
     class NonExistentTable < ActiveRecord::Base
@@ -126,12 +126,12 @@ module ActiveRecord
     end
 
     def test_statement_key_is_logged
-      bindval = 1
-      @connection.exec_query('SELECT $1::integer', 'SQL', [[nil, bindval]])
+      bind = Relation::QueryAttribute.new(nil, 1, Type::Value.new)
+      @connection.exec_query('SELECT $1::integer', 'SQL', [bind], prepare: true)
       name = @subscriber.payloads.last[:statement_name]
       assert name
-      res = @connection.exec_query("EXPLAIN (FORMAT JSON) EXECUTE #{name}(#{bindval})")
-      plan = res.column_types['QUERY PLAN'].type_cast_from_database res.rows.first.first
+      res = @connection.exec_query("EXPLAIN (FORMAT JSON) EXECUTE #{name}(1)")
+      plan = res.column_types['QUERY PLAN'].deserialize res.rows.first.first
       assert_operator plan.length, :>, 0
     end
 
diff --git a/activerecord/test/cases/adapters/postgresql/datatype_test.rb b/activerecord/test/cases/adapters/postgresql/datatype_test.rb
index 4f48a7bce3..232c25cb3b 100644
--- a/activerecord/test/cases/adapters/postgresql/datatype_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/datatype_test.rb
@@ -11,8 +11,8 @@ end
 class PostgresqlLtree < ActiveRecord::Base
 end
 
-class PostgresqlDataTypeTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+class PostgresqlDataTypeTest < ActiveRecord::PostgreSQLTestCase
+  self.use_transactional_tests = false
 
   def setup
     @connection = ActiveRecord::Base.connection
@@ -69,7 +69,7 @@ class PostgresqlDataTypeTest < ActiveRecord::TestCase
   end
 end
 
-class PostgresqlInternalDataTypeTest < ActiveRecord::TestCase
+class PostgresqlInternalDataTypeTest < ActiveRecord::PostgreSQLTestCase
   include DdlHelper
 
   setup do
diff --git a/activerecord/test/cases/adapters/postgresql/domain_test.rb b/activerecord/test/cases/adapters/postgresql/domain_test.rb
index ebb04814bb..6102ddacd1 100644
--- a/activerecord/test/cases/adapters/postgresql/domain_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/domain_test.rb
@@ -1,8 +1,7 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 
-class PostgresqlDomainTest < ActiveRecord::TestCase
+class PostgresqlDomainTest < ActiveRecord::PostgreSQLTestCase
   include ConnectionHelper
 
   class PostgresqlDomain < ActiveRecord::Base
@@ -20,7 +19,7 @@ class PostgresqlDomainTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_domains'
+    @connection.drop_table 'postgresql_domains', if_exists: true
     @connection.execute 'DROP DOMAIN IF EXISTS custom_money'
     reset_connection
   end
@@ -29,9 +28,10 @@ class PostgresqlDomainTest < ActiveRecord::TestCase
     column = PostgresqlDomain.columns_hash["price"]
     assert_equal :decimal, column.type
     assert_equal "custom_money", column.sql_type
-    assert column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlDomain.type_for_attribute("price")
+    assert_not type.binary?
   end
 
   def test_domain_acts_like_basetype
diff --git a/activerecord/test/cases/adapters/postgresql/enum_test.rb b/activerecord/test/cases/adapters/postgresql/enum_test.rb
index 88b3b2cc0e..6816a6514b 100644
--- a/activerecord/test/cases/adapters/postgresql/enum_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/enum_test.rb
@@ -1,8 +1,7 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 
-class PostgresqlEnumTest < ActiveRecord::TestCase
+class PostgresqlEnumTest < ActiveRecord::PostgreSQLTestCase
   include ConnectionHelper
 
   class PostgresqlEnum < ActiveRecord::Base
@@ -22,7 +21,7 @@ class PostgresqlEnumTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_enums'
+    @connection.drop_table 'postgresql_enums', if_exists: true
     @connection.execute 'DROP TYPE IF EXISTS mood'
     reset_connection
   end
@@ -31,9 +30,10 @@ class PostgresqlEnumTest < ActiveRecord::TestCase
     column = PostgresqlEnum.columns_hash["current_mood"]
     assert_equal :enum, column.type
     assert_equal "mood", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlEnum.type_for_attribute("current_mood")
+    assert_not type.binary?
   end
 
   def test_enum_defaults
@@ -80,4 +80,12 @@ class PostgresqlEnumTest < ActiveRecord::TestCase
 
     assert_equal "happy", enum.current_mood
   end
+
+  def test_assigning_enum_to_nil
+    model = PostgresqlEnum.new(current_mood: nil)
+
+    assert_nil model.current_mood
+    assert model.save
+    assert_nil model.reload.current_mood
+  end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/explain_test.rb b/activerecord/test/cases/adapters/postgresql/explain_test.rb
index 6ffb4c9f33..4d0fd640aa 100644
--- a/activerecord/test/cases/adapters/postgresql/explain_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/explain_test.rb
@@ -2,25 +2,19 @@ require "cases/helper"
 require 'models/developer'
 require 'models/computer'
 
-module ActiveRecord
-  module ConnectionAdapters
-    class PostgreSQLAdapter
-      class ExplainTest < ActiveRecord::TestCase
-        fixtures :developers
+class PostgreSQLExplainTest < ActiveRecord::PostgreSQLTestCase
+  fixtures :developers
 
-        def test_explain_for_one_query
-          explain = Developer.where(:id => 1).explain
-          assert_match %(EXPLAIN for: SELECT "developers".* FROM "developers" WHERE "developers"."id" = $1), explain
-          assert_match %(QUERY PLAN), explain
-        end
+  def test_explain_for_one_query
+    explain = Developer.where(:id => 1).explain
+    assert_match %(EXPLAIN for: SELECT "developers".* FROM "developers" WHERE "developers"."id" = $1), explain
+    assert_match %(QUERY PLAN), explain
+  end
 
-        def test_explain_with_eager_loading
-          explain = Developer.where(:id => 1).includes(:audit_logs).explain
-          assert_match %(QUERY PLAN), explain
-          assert_match %(EXPLAIN for: SELECT "developers".* FROM "developers" WHERE "developers"."id" = $1), explain
-          assert_match %(EXPLAIN for: SELECT "audit_logs".* FROM "audit_logs" WHERE "audit_logs"."developer_id" = 1), explain
-        end
-      end
-    end
+  def test_explain_with_eager_loading
+    explain = Developer.where(:id => 1).includes(:audit_logs).explain
+    assert_match %(QUERY PLAN), explain
+    assert_match %(EXPLAIN for: SELECT "developers".* FROM "developers" WHERE "developers"."id" = $1), explain
+    assert_match %(EXPLAIN for: SELECT "audit_logs".* FROM "audit_logs" WHERE "audit_logs"."developer_id" = 1), explain
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/extension_migration_test.rb b/activerecord/test/cases/adapters/postgresql/extension_migration_test.rb
index 7b99fcdda0..9cfc133308 100644
--- a/activerecord/test/cases/adapters/postgresql/extension_migration_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/extension_migration_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 
-class PostgresqlExtensionMigrationTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+class PostgresqlExtensionMigrationTest < ActiveRecord::PostgreSQLTestCase
+  self.use_transactional_tests = false
 
   class EnableHstore < ActiveRecord::Migration
     def change
diff --git a/activerecord/test/cases/adapters/postgresql/full_text_test.rb b/activerecord/test/cases/adapters/postgresql/full_text_test.rb
index a370a5adc6..bde7513339 100644
--- a/activerecord/test/cases/adapters/postgresql/full_text_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/full_text_test.rb
@@ -1,8 +1,7 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
-class PostgresqlFullTextTest < ActiveRecord::TestCase
+class PostgresqlFullTextTest < ActiveRecord::PostgreSQLTestCase
   include SchemaDumpingHelper
   class Tsvector < ActiveRecord::Base; end
 
@@ -14,16 +13,17 @@ class PostgresqlFullTextTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute 'DROP TABLE IF EXISTS tsvectors;'
+    @connection.drop_table 'tsvectors', if_exists: true
   end
 
   def test_tsvector_column
     column = Tsvector.columns_hash["text_vector"]
     assert_equal :tsvector, column.type
     assert_equal "tsvector", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = Tsvector.type_for_attribute("text_vector")
+    assert_not type.binary?
   end
 
   def test_update_tsvector
@@ -39,6 +39,6 @@ class PostgresqlFullTextTest < ActiveRecord::TestCase
 
   def test_schema_dump_with_shorthand
     output = dump_table_schema("tsvectors")
-    assert_match %r{t.tsvector "text_vector"}, output
+    assert_match %r{t\.tsvector "text_vector"}, output
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/geometric_test.rb b/activerecord/test/cases/adapters/postgresql/geometric_test.rb
index ed2bf554bb..0baf985654 100644
--- a/activerecord/test/cases/adapters/postgresql/geometric_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/geometric_test.rb
@@ -1,13 +1,20 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 require 'support/schema_dumping_helper'
 
-class PostgresqlPointTest < ActiveRecord::TestCase
+class PostgresqlPointTest < ActiveRecord::PostgreSQLTestCase
   include ConnectionHelper
   include SchemaDumpingHelper
 
-  class PostgresqlPoint < ActiveRecord::Base; end
+  class PostgresqlPoint < ActiveRecord::Base
+    attribute :x, :rails_5_1_point
+    attribute :y, :rails_5_1_point
+    attribute :z, :rails_5_1_point
+    attribute :array_of_points, :rails_5_1_point, array: true
+    attribute :legacy_x, :legacy_point
+    attribute :legacy_y, :legacy_point
+    attribute :legacy_z, :legacy_point
+  end
 
   def setup
     @connection = ActiveRecord::Base.connection
@@ -15,28 +22,45 @@ class PostgresqlPointTest < ActiveRecord::TestCase
       t.point :x
       t.point :y, default: [12.2, 13.3]
       t.point :z, default: "(14.4,15.5)"
+      t.point :array_of_points, array: true
+      t.point :legacy_x
+      t.point :legacy_y, default: [12.2, 13.3]
+      t.point :legacy_z, default: "(14.4,15.5)"
+    end
+    @connection.create_table('deprecated_points') do |t|
+      t.point :x
     end
   end
 
   teardown do
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_points'
+    @connection.drop_table 'postgresql_points', if_exists: true
+    @connection.drop_table 'deprecated_points', if_exists: true
+  end
+
+  class DeprecatedPoint < ActiveRecord::Base; end
+
+  def test_deprecated_legacy_type
+    assert_deprecated do
+      DeprecatedPoint.new
+    end
   end
 
   def test_column
     column = PostgresqlPoint.columns_hash["x"]
     assert_equal :point, column.type
     assert_equal "point", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlPoint.type_for_attribute("x")
+    assert_not type.binary?
   end
 
   def test_default
-    assert_equal [12.2, 13.3], PostgresqlPoint.column_defaults['y']
-    assert_equal [12.2, 13.3], PostgresqlPoint.new.y
+    assert_equal ActiveRecord::Point.new(12.2, 13.3), PostgresqlPoint.column_defaults['y']
+    assert_equal ActiveRecord::Point.new(12.2, 13.3), PostgresqlPoint.new.y
 
-    assert_equal [14.4, 15.5], PostgresqlPoint.column_defaults['z']
-    assert_equal [14.4, 15.5], PostgresqlPoint.new.z
+    assert_equal ActiveRecord::Point.new(14.4, 15.5), PostgresqlPoint.column_defaults['z']
+    assert_equal ActiveRecord::Point.new(14.4, 15.5), PostgresqlPoint.new.z
   end
 
   def test_schema_dumping
@@ -49,27 +73,100 @@ class PostgresqlPointTest < ActiveRecord::TestCase
   def test_roundtrip
     PostgresqlPoint.create! x: [10, 25.2]
     record = PostgresqlPoint.first
-    assert_equal [10, 25.2], record.x
+    assert_equal ActiveRecord::Point.new(10, 25.2), record.x
 
-    record.x = [1.1, 2.2]
+    record.x = ActiveRecord::Point.new(1.1, 2.2)
     record.save!
     assert record.reload
-    assert_equal [1.1, 2.2], record.x
+    assert_equal ActiveRecord::Point.new(1.1, 2.2), record.x
   end
 
   def test_mutation
-    p = PostgresqlPoint.create! x: [10, 20]
+    p = PostgresqlPoint.create! x: ActiveRecord::Point.new(10, 20)
+
+    p.x.y = 25
+    p.save!
+    p.reload
+
+    assert_equal ActiveRecord::Point.new(10.0, 25.0), p.x
+    assert_not p.changed?
+  end
+
+  def test_array_assignment
+    p = PostgresqlPoint.new(x: [1, 2])
+
+    assert_equal ActiveRecord::Point.new(1, 2), p.x
+  end
+
+  def test_string_assignment
+    p = PostgresqlPoint.new(x: "(1, 2)")
+
+    assert_equal ActiveRecord::Point.new(1, 2), p.x
+  end
+
+  def test_array_of_points_round_trip
+    expected_value = [
+      ActiveRecord::Point.new(1, 2),
+      ActiveRecord::Point.new(2, 3),
+      ActiveRecord::Point.new(3, 4),
+    ]
+    p = PostgresqlPoint.new(array_of_points: expected_value)
+
+    assert_equal expected_value, p.array_of_points
+    p.save!
+    p.reload
+    assert_equal expected_value, p.array_of_points
+  end
+
+  def test_legacy_column
+    column = PostgresqlPoint.columns_hash["legacy_x"]
+    assert_equal :point, column.type
+    assert_equal "point", column.sql_type
+    assert_not column.array?
+
+    type = PostgresqlPoint.type_for_attribute("legacy_x")
+    assert_not type.binary?
+  end
+
+  def test_legacy_default
+    assert_equal [12.2, 13.3], PostgresqlPoint.column_defaults['legacy_y']
+    assert_equal [12.2, 13.3], PostgresqlPoint.new.legacy_y
+
+    assert_equal [14.4, 15.5], PostgresqlPoint.column_defaults['legacy_z']
+    assert_equal [14.4, 15.5], PostgresqlPoint.new.legacy_z
+  end
+
+  def test_legacy_schema_dumping
+    output = dump_table_schema("postgresql_points")
+    assert_match %r{t\.point\s+"legacy_x"$}, output
+    assert_match %r{t\.point\s+"legacy_y",\s+default: \[12\.2, 13\.3\]$}, output
+    assert_match %r{t\.point\s+"legacy_z",\s+default: \[14\.4, 15\.5\]$}, output
+  end
+
+  def test_legacy_roundtrip
+    PostgresqlPoint.create! legacy_x: [10, 25.2]
+    record = PostgresqlPoint.first
+    assert_equal [10, 25.2], record.legacy_x
+
+    record.legacy_x = [1.1, 2.2]
+    record.save!
+    assert record.reload
+    assert_equal [1.1, 2.2], record.legacy_x
+  end
+
+  def test_legacy_mutation
+    p = PostgresqlPoint.create! legacy_x: [10, 20]
 
-    p.x[1] = 25
+    p.legacy_x[1] = 25
     p.save!
     p.reload
 
-    assert_equal [10.0, 25.0], p.x
+    assert_equal [10.0, 25.0], p.legacy_x
     assert_not p.changed?
   end
 end
 
-class PostgresqlGeometricTest < ActiveRecord::TestCase
+class PostgresqlGeometricTest < ActiveRecord::PostgreSQLTestCase
   class PostgresqlGeometric < ActiveRecord::Base; end
 
   setup do
@@ -84,7 +181,7 @@ class PostgresqlGeometricTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_geometrics'
+    @connection.drop_table 'postgresql_geometrics', if_exists: true
   end
 
   def test_geometric_types
diff --git a/activerecord/test/cases/adapters/postgresql/hstore_test.rb b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
index a0aa10630c..6a2d501646 100644
--- a/activerecord/test/cases/adapters/postgresql/hstore_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
@@ -1,9 +1,8 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
 if ActiveRecord::Base.connection.supports_extensions?
-  class PostgresqlHstoreTest < ActiveRecord::TestCase
+  class PostgresqlHstoreTest < ActiveRecord::PostgreSQLTestCase
     include SchemaDumpingHelper
     class Hstore < ActiveRecord::Base
       self.table_name = 'hstores'
@@ -28,11 +27,13 @@ if ActiveRecord::Base.connection.supports_extensions?
           t.hstore 'settings'
         end
       end
+      Hstore.reset_column_information
       @column = Hstore.columns_hash['tags']
+      @type = Hstore.type_for_attribute("tags")
     end
 
     teardown do
-      @connection.execute 'drop table if exists hstores'
+      @connection.drop_table 'hstores', if_exists: true
     end
 
     def test_hstore_included_in_extensions
@@ -54,9 +55,9 @@ if ActiveRecord::Base.connection.supports_extensions?
     def test_column
       assert_equal :hstore, @column.type
       assert_equal "hstore", @column.sql_type
-      assert_not @column.number?
-      assert_not @column.binary?
       assert_not @column.array?
+
+      assert_not @type.binary?
     end
 
     def test_default
@@ -110,10 +111,10 @@ if ActiveRecord::Base.connection.supports_extensions?
     end
 
     def test_type_cast_hstore
-      assert_equal({'1' => '2'}, @column.type_cast_from_database("\"1\"=>\"2\""))
-      assert_equal({}, @column.type_cast_from_database(""))
-      assert_equal({'key'=>nil}, @column.type_cast_from_database('key => NULL'))
-      assert_equal({'c'=>'}','"a"'=>'b "a b'}, @column.type_cast_from_database(%q(c=>"}", "\"a\""=>"b \"a b")))
+      assert_equal({'1' => '2'}, @type.deserialize("\"1\"=>\"2\""))
+      assert_equal({}, @type.deserialize(""))
+      assert_equal({'key'=>nil}, @type.deserialize('key => NULL'))
+      assert_equal({'c'=>'}','"a"'=>'b "a b'}, @type.deserialize(%q(c=>"}", "\"a\""=>"b \"a b")))
     end
 
     def test_with_store_accessors
@@ -165,47 +166,47 @@ if ActiveRecord::Base.connection.supports_extensions?
     end
 
     def test_gen1
-      assert_equal(%q(" "=>""), @column.cast_type.type_cast_for_database({' '=>''}))
+      assert_equal(%q(" "=>""), @type.serialize({' '=>''}))
     end
 
     def test_gen2
-      assert_equal(%q(","=>""), @column.cast_type.type_cast_for_database({','=>''}))
+      assert_equal(%q(","=>""), @type.serialize({','=>''}))
     end
 
     def test_gen3
-      assert_equal(%q("="=>""), @column.cast_type.type_cast_for_database({'='=>''}))
+      assert_equal(%q("="=>""), @type.serialize({'='=>''}))
     end
 
     def test_gen4
-      assert_equal(%q(">"=>""), @column.cast_type.type_cast_for_database({'>'=>''}))
+      assert_equal(%q(">"=>""), @type.serialize({'>'=>''}))
     end
 
     def test_parse1
-      assert_equal({'a'=>nil,'b'=>nil,'c'=>'NuLl','null'=>'c'}, @column.type_cast_from_database('a=>null,b=>NuLl,c=>"NuLl",null=>c'))
+      assert_equal({'a'=>nil,'b'=>nil,'c'=>'NuLl','null'=>'c'}, @type.deserialize('a=>null,b=>NuLl,c=>"NuLl",null=>c'))
     end
 
     def test_parse2
-      assert_equal({" " => " "},  @column.type_cast_from_database("\\ =>\\ "))
+      assert_equal({" " => " "},  @type.deserialize("\\ =>\\ "))
     end
 
     def test_parse3
-      assert_equal({"=" => ">"},  @column.type_cast_from_database("==>>"))
+      assert_equal({"=" => ">"},  @type.deserialize("==>>"))
     end
 
     def test_parse4
-      assert_equal({"=a"=>"q=w"},   @column.type_cast_from_database('\=a=>q=w'))
+      assert_equal({"=a"=>"q=w"},   @type.deserialize('\=a=>q=w'))
     end
 
     def test_parse5
-      assert_equal({"=a"=>"q=w"},   @column.type_cast_from_database('"=a"=>q\=w'))
+      assert_equal({"=a"=>"q=w"},   @type.deserialize('"=a"=>q\=w'))
     end
 
     def test_parse6
-      assert_equal({"\"a"=>"q>w"},  @column.type_cast_from_database('"\"a"=>q>w'))
+      assert_equal({"\"a"=>"q>w"},  @type.deserialize('"\"a"=>q>w'))
     end
 
     def test_parse7
-      assert_equal({"\"a"=>"q\"w"}, @column.type_cast_from_database('\"a=>q"w'))
+      assert_equal({"\"a"=>"q\"w"}, @type.deserialize('\"a=>q"w'))
     end
 
     def test_rewrite
@@ -317,7 +318,7 @@ if ActiveRecord::Base.connection.supports_extensions?
 
     def test_schema_dump_with_shorthand
       output = dump_table_schema("hstores")
-      assert_match %r[t.hstore "tags",\s+default: {}], output
+      assert_match %r[t\.hstore "tags",\s+default: {}], output
     end
 
     private
diff --git a/activerecord/test/cases/adapters/postgresql/infinity_test.rb b/activerecord/test/cases/adapters/postgresql/infinity_test.rb
index 74163ac712..bfda933fa4 100644
--- a/activerecord/test/cases/adapters/postgresql/infinity_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/infinity_test.rb
@@ -1,6 +1,6 @@
 require "cases/helper"
 
-class PostgresqlInfinityTest < ActiveRecord::TestCase
+class PostgresqlInfinityTest < ActiveRecord::PostgreSQLTestCase
   include InTimeZone
 
   class PostgresqlInfinity < ActiveRecord::Base
@@ -15,7 +15,7 @@ class PostgresqlInfinityTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute("DROP TABLE IF EXISTS postgresql_infinities")
+    @connection.drop_table 'postgresql_infinities', if_exists: true
   end
 
   test "type casting infinity on a float column" do
@@ -24,6 +24,15 @@ class PostgresqlInfinityTest < ActiveRecord::TestCase
     assert_equal Float::INFINITY, record.float
   end
 
+  test "type casting string on a float column" do
+    record = PostgresqlInfinity.new(float: 'Infinity')
+    assert_equal Float::INFINITY, record.float
+    record = PostgresqlInfinity.new(float: '-Infinity')
+    assert_equal(-Float::INFINITY, record.float)
+    record = PostgresqlInfinity.new(float: 'NaN')
+    assert_send [record.float, :nan?]
+  end
+
   test "update_all with infinity on a float column" do
     record = PostgresqlInfinity.create!
     PostgresqlInfinity.update_all(float: Float::INFINITY)
diff --git a/activerecord/test/cases/adapters/postgresql/integer_test.rb b/activerecord/test/cases/adapters/postgresql/integer_test.rb
index 7f8751281e..b4e55964b9 100644
--- a/activerecord/test/cases/adapters/postgresql/integer_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/integer_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 require "active_support/core_ext/numeric/bytes"
 
-class PostgresqlIntegerTest < ActiveRecord::TestCase
+class PostgresqlIntegerTest < ActiveRecord::PostgreSQLTestCase
   class PgInteger < ActiveRecord::Base
   end
 
@@ -16,7 +16,7 @@ class PostgresqlIntegerTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute "drop table if exists pg_integers"
+    @connection.drop_table "pg_integers", if_exists: true
   end
 
   test "schema properly respects bigint ranges" do
diff --git a/activerecord/test/cases/adapters/postgresql/json_test.rb b/activerecord/test/cases/adapters/postgresql/json_test.rb
index 7be7e00463..b3b121b4fb 100644
--- a/activerecord/test/cases/adapters/postgresql/json_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/json_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
@@ -14,29 +13,28 @@ module PostgresqlJSONSharedTestCases
   def setup
     @connection = ActiveRecord::Base.connection
     begin
-      @connection.transaction do
-        @connection.create_table('json_data_type') do |t|
-          t.public_send column_type, 'payload', default: {} # t.json 'payload', default: {}
-          t.public_send column_type, 'settings'             # t.json 'settings'
-        end
+      @connection.create_table('json_data_type') do |t|
+        t.public_send column_type, 'payload', default: {} # t.json 'payload', default: {}
+        t.public_send column_type, 'settings'             # t.json 'settings'
       end
     rescue ActiveRecord::StatementInvalid
-      skip "do not test on PG without json"
+      skip "do not test on PostgreSQL without #{column_type} type."
     end
-    @column = JsonDataType.columns_hash['payload']
   end
 
   def teardown
-    @connection.execute 'drop table if exists json_data_type'
+    @connection.drop_table :json_data_type, if_exists: true
+    JsonDataType.reset_column_information
   end
 
   def test_column
     column = JsonDataType.columns_hash["payload"]
     assert_equal column_type, column.type
     assert_equal column_type.to_s, column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = JsonDataType.type_for_attribute("payload")
+    assert_not type.binary?
   end
 
   def test_default
@@ -66,7 +64,7 @@ module PostgresqlJSONSharedTestCases
 
   def test_schema_dumping
     output = dump_table_schema("json_data_type")
-    assert_match(/t.#{column_type.to_s}\s+"payload",\s+default: {}/, output)
+    assert_match(/t\.#{column_type.to_s}\s+"payload",\s+default: {}/, output)
   end
 
   def test_cast_value_on_write
@@ -78,16 +76,16 @@ module PostgresqlJSONSharedTestCases
   end
 
   def test_type_cast_json
-    column = JsonDataType.columns_hash["payload"]
+    type = JsonDataType.type_for_attribute("payload")
 
     data = "{\"a_key\":\"a_value\"}"
-    hash = column.type_cast_from_database(data)
+    hash = type.deserialize(data)
     assert_equal({'a_key' => 'a_value'}, hash)
-    assert_equal({'a_key' => 'a_value'}, column.type_cast_from_database(data))
+    assert_equal({'a_key' => 'a_value'}, type.deserialize(data))
 
-    assert_equal({}, column.type_cast_from_database("{}"))
-    assert_equal({'key'=>nil}, column.type_cast_from_database('{"key": null}'))
-    assert_equal({'c'=>'}','"a"'=>'b "a b'}, column.type_cast_from_database(%q({"c":"}", "\"a\"":"b \"a b"})))
+    assert_equal({}, type.deserialize("{}"))
+    assert_equal({'key'=>nil}, type.deserialize('{"key": null}'))
+    assert_equal({'c'=>'}','"a"'=>'b "a b'}, type.deserialize(%q({"c":"}", "\"a\"":"b \"a b"})))
   end
 
   def test_rewrite
@@ -179,9 +177,17 @@ module PostgresqlJSONSharedTestCases
     assert_equal({ 'one' => 'two', 'three' => 'four' }, json.payload)
     assert_not json.changed?
   end
+
+  def test_assigning_invalid_json
+    json = JsonDataType.new
+
+    json.payload = 'foo'
+
+    assert_nil json.payload
+  end
 end
 
-class PostgresqlJSONTest < ActiveRecord::TestCase
+class PostgresqlJSONTest < ActiveRecord::PostgreSQLTestCase
   include PostgresqlJSONSharedTestCases
 
   def column_type
@@ -189,7 +195,7 @@ class PostgresqlJSONTest < ActiveRecord::TestCase
   end
 end
 
-class PostgresqlJSONBTest < ActiveRecord::TestCase
+class PostgresqlJSONBTest < ActiveRecord::PostgreSQLTestCase
   include PostgresqlJSONSharedTestCases
 
   def column_type
diff --git a/activerecord/test/cases/adapters/postgresql/ltree_test.rb b/activerecord/test/cases/adapters/postgresql/ltree_test.rb
index 771a825840..56516c82b4 100644
--- a/activerecord/test/cases/adapters/postgresql/ltree_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/ltree_test.rb
@@ -1,8 +1,7 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
-class PostgresqlLtreeTest < ActiveRecord::TestCase
+class PostgresqlLtreeTest < ActiveRecord::PostgreSQLTestCase
   include SchemaDumpingHelper
   class Ltree < ActiveRecord::Base
     self.table_name = 'ltrees'
@@ -23,16 +22,17 @@ class PostgresqlLtreeTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute 'drop table if exists ltrees'
+    @connection.drop_table 'ltrees', if_exists: true
   end
 
   def test_column
     column = Ltree.columns_hash['path']
     assert_equal :ltree, column.type
     assert_equal "ltree", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = Ltree.type_for_attribute('path')
+    assert_not type.binary?
   end
 
   def test_write
@@ -48,6 +48,6 @@ class PostgresqlLtreeTest < ActiveRecord::TestCase
 
   def test_schema_dump_with_shorthand
     output = dump_table_schema("ltrees")
-    assert_match %r[t.ltree "path"], output
+    assert_match %r[t\.ltree "path"], output
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/money_test.rb b/activerecord/test/cases/adapters/postgresql/money_test.rb
index f3a24eee85..c031178479 100644
--- a/activerecord/test/cases/adapters/postgresql/money_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/money_test.rb
@@ -1,8 +1,7 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
-class PostgresqlMoneyTest < ActiveRecord::TestCase
+class PostgresqlMoneyTest < ActiveRecord::PostgreSQLTestCase
   include SchemaDumpingHelper
 
   class PostgresqlMoney < ActiveRecord::Base; end
@@ -11,13 +10,13 @@ class PostgresqlMoneyTest < ActiveRecord::TestCase
     @connection = ActiveRecord::Base.connection
     @connection.execute("set lc_monetary = 'C'")
     @connection.create_table('postgresql_moneys', force: true) do |t|
-      t.column "wealth", "money"
-      t.column "depth", "money", default: "150.55"
+      t.money "wealth"
+      t.money "depth", default: "150.55"
     end
   end
 
   teardown do
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_moneys'
+    @connection.drop_table 'postgresql_moneys', if_exists: true
   end
 
   def test_column
@@ -25,9 +24,10 @@ class PostgresqlMoneyTest < ActiveRecord::TestCase
     assert_equal :money, column.type
     assert_equal "money", column.sql_type
     assert_equal 2, column.scale
-    assert column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlMoney.type_for_attribute("wealth")
+    assert_not type.binary?
   end
 
   def test_default
@@ -46,17 +46,17 @@ class PostgresqlMoneyTest < ActiveRecord::TestCase
   end
 
   def test_money_type_cast
-    column = PostgresqlMoney.columns_hash['wealth']
-    assert_equal(12345678.12, column.type_cast_from_user("$12,345,678.12"))
-    assert_equal(12345678.12, column.type_cast_from_user("$12.345.678,12"))
-    assert_equal(-1.15, column.type_cast_from_user("-$1.15"))
-    assert_equal(-2.25, column.type_cast_from_user("($2.25)"))
+    type = PostgresqlMoney.type_for_attribute('wealth')
+    assert_equal(12345678.12, type.cast("$12,345,678.12"))
+    assert_equal(12345678.12, type.cast("$12.345.678,12"))
+    assert_equal(-1.15, type.cast("-$1.15"))
+    assert_equal(-2.25, type.cast("($2.25)"))
   end
 
   def test_schema_dumping
     output = dump_table_schema("postgresql_moneys")
     assert_match %r{t\.money\s+"wealth",\s+scale: 2$}, output
-    assert_match %r{t\.money\s+"depth",\s+scale: 2,\s+default: 150.55$}, output
+    assert_match %r{t\.money\s+"depth",\s+scale: 2,\s+default: "150\.55"$}, output
   end
 
   def test_create_and_update_money
diff --git a/activerecord/test/cases/adapters/postgresql/network_test.rb b/activerecord/test/cases/adapters/postgresql/network_test.rb
index daa590f369..fe6ee4e2d9 100644
--- a/activerecord/test/cases/adapters/postgresql/network_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/network_test.rb
@@ -1,8 +1,7 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
-class PostgresqlNetworkTest < ActiveRecord::TestCase
+class PostgresqlNetworkTest < ActiveRecord::PostgreSQLTestCase
   include SchemaDumpingHelper
   class PostgresqlNetworkAddress < ActiveRecord::Base; end
 
@@ -16,34 +15,37 @@ class PostgresqlNetworkTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_network_addresses'
+    @connection.drop_table 'postgresql_network_addresses', if_exists: true
   end
 
   def test_cidr_column
     column = PostgresqlNetworkAddress.columns_hash["cidr_address"]
     assert_equal :cidr, column.type
     assert_equal "cidr", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlNetworkAddress.type_for_attribute("cidr_address")
+    assert_not type.binary?
   end
 
   def test_inet_column
     column = PostgresqlNetworkAddress.columns_hash["inet_address"]
     assert_equal :inet, column.type
     assert_equal "inet", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlNetworkAddress.type_for_attribute("inet_address")
+    assert_not type.binary?
   end
 
   def test_macaddr_column
     column = PostgresqlNetworkAddress.columns_hash["mac_address"]
     assert_equal :macaddr, column.type
     assert_equal "macaddr", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = PostgresqlNetworkAddress.type_for_attribute("mac_address")
+    assert_not type.binary?
   end
 
   def test_network_types
@@ -85,8 +87,8 @@ class PostgresqlNetworkTest < ActiveRecord::TestCase
 
   def test_schema_dump_with_shorthand
     output = dump_table_schema("postgresql_network_addresses")
-    assert_match %r{t.inet\s+"inet_address",\s+default: "192.168.1.1"}, output
-    assert_match %r{t.cidr\s+"cidr_address",\s+default: "192.168.1.0/24"}, output
-    assert_match %r{t.macaddr\s+"mac_address",\s+default: "ff:ff:ff:ff:ff:ff"}, output
+    assert_match %r{t\.inet\s+"inet_address",\s+default: "192\.168\.1\.1"}, output
+    assert_match %r{t\.cidr\s+"cidr_address",\s+default: "192\.168\.1\.0/24"}, output
+    assert_match %r{t\.macaddr\s+"mac_address",\s+default: "ff:ff:ff:ff:ff:ff"}, output
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/numbers_test.rb b/activerecord/test/cases/adapters/postgresql/numbers_test.rb
index 70aa898439..ba7e7dc9a3 100644
--- a/activerecord/test/cases/adapters/postgresql/numbers_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/numbers_test.rb
@@ -1,6 +1,6 @@
 require "cases/helper"
 
-class PostgresqlNumberTest < ActiveRecord::TestCase
+class PostgresqlNumberTest < ActiveRecord::PostgreSQLTestCase
   class PostgresqlNumber < ActiveRecord::Base; end
 
   setup do
@@ -12,7 +12,7 @@ class PostgresqlNumberTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_numbers'
+    @connection.drop_table 'postgresql_numbers', if_exists: true
   end
 
   def test_data_type
@@ -31,7 +31,7 @@ class PostgresqlNumberTest < ActiveRecord::TestCase
     assert_equal 123456.789, first.double
     assert_equal(-::Float::INFINITY, second.single)
     assert_equal ::Float::INFINITY, second.double
-    assert_same ::Float::NAN, third.double
+    assert_send [third.double, :nan?]
   end
 
   def test_update
diff --git a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
index 6bb2b26cd5..e361521155 100644
--- a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
@@ -1,11 +1,10 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/ddl_helper'
 require 'support/connection_helper'
 
 module ActiveRecord
   module ConnectionAdapters
-    class PostgreSQLAdapterTest < ActiveRecord::TestCase
+    class PostgreSQLAdapterTest < ActiveRecord::PostgreSQLTestCase
       include DdlHelper
       include ConnectionHelper
 
@@ -69,7 +68,7 @@ module ActiveRecord
       def test_insert_sql_with_proprietary_returning_clause
         with_example_table do
           id = @connection.insert_sql("insert into ex (number) values(5150)", nil, "number")
-          assert_equal "5150", id
+          assert_equal 5150, id
         end
       end
 
@@ -107,21 +106,35 @@ module ActiveRecord
         connection = connection_without_insert_returning
         id = connection.insert_sql("insert into postgresql_partitioned_table_parent (number) VALUES (1)")
         expect = connection.query('select max(id) from postgresql_partitioned_table_parent').first.first
-        assert_equal expect, id
+        assert_equal expect.to_i, id
       end
 
       def test_exec_insert_with_returning_disabled
         connection = connection_without_insert_returning
         result = connection.exec_insert("insert into postgresql_partitioned_table_parent (number) VALUES (1)", nil, [], 'id', 'postgresql_partitioned_table_parent_id_seq')
         expect = connection.query('select max(id) from postgresql_partitioned_table_parent').first.first
-        assert_equal expect, result.rows.first.first
+        assert_equal expect.to_i, result.rows.first.first
       end
 
       def test_exec_insert_with_returning_disabled_and_no_sequence_name_given
         connection = connection_without_insert_returning
         result = connection.exec_insert("insert into postgresql_partitioned_table_parent (number) VALUES (1)", nil, [], 'id')
         expect = connection.query('select max(id) from postgresql_partitioned_table_parent').first.first
-        assert_equal expect, result.rows.first.first
+        assert_equal expect.to_i, result.rows.first.first
+      end
+
+      def test_exec_insert_default_values_with_returning_disabled_and_no_sequence_name_given
+        connection = connection_without_insert_returning
+        result = connection.exec_insert("insert into postgresql_partitioned_table_parent DEFAULT VALUES", nil, [], 'id')
+        expect = connection.query('select max(id) from postgresql_partitioned_table_parent').first.first
+        assert_equal expect.to_i, result.rows.first.first
+      end
+
+      def test_exec_insert_default_values_quoted_schema_with_returning_disabled_and_no_sequence_name_given
+        connection = connection_without_insert_returning
+        result = connection.exec_insert('insert into "public"."postgresql_partitioned_table_parent" DEFAULT VALUES', nil, [], 'id')
+        expect = connection.query('select max(id) from postgresql_partitioned_table_parent').first.first
+        assert_equal expect.to_i, result.rows.first.first
       end
 
       def test_sql_for_insert_with_returning_disabled
@@ -228,8 +241,8 @@ module ActiveRecord
           "DELETE FROM pg_depend WHERE objid = 'ex2_id_seq'::regclass AND refobjid = 'ex'::regclass AND deptype = 'a'"
         )
       ensure
-        @connection.exec_query('DROP TABLE IF EXISTS ex')
-        @connection.exec_query('DROP TABLE IF EXISTS ex2')
+        @connection.drop_table 'ex', if_exists: true
+        @connection.drop_table 'ex2', if_exists: true
       end
 
       def test_exec_insert_number
@@ -239,7 +252,7 @@ module ActiveRecord
           result = @connection.exec_query('SELECT number FROM ex WHERE number = 10')
 
           assert_equal 1, result.rows.length
-          assert_equal "10", result.rows.last.last
+          assert_equal 10, result.rows.last.last
         end
       end
 
@@ -275,7 +288,7 @@ module ActiveRecord
           assert_equal 1, result.rows.length
           assert_equal 2, result.columns.length
 
-          assert_equal [['1', 'foo']], result.rows
+          assert_equal [[1, 'foo']], result.rows
         end
       end
 
@@ -284,12 +297,12 @@ module ActiveRecord
           string = @connection.quote('foo')
           @connection.exec_query("INSERT INTO ex (id, data) VALUES (1, #{string})")
           result = @connection.exec_query(
-                                          'SELECT id, data FROM ex WHERE id = $1', nil, [[nil, 1]])
+                                          'SELECT id, data FROM ex WHERE id = $1', nil, [bind_param(1)])
 
           assert_equal 1, result.rows.length
           assert_equal 2, result.columns.length
 
-          assert_equal [['1', 'foo']], result.rows
+          assert_equal [[1, 'foo']], result.rows
         end
       end
 
@@ -298,14 +311,14 @@ module ActiveRecord
           string = @connection.quote('foo')
           @connection.exec_query("INSERT INTO ex (id, data) VALUES (1, #{string})")
 
-          column = @connection.columns('ex').find { |col| col.name == 'id' }
+          bind = ActiveRecord::Relation::QueryAttribute.new("id", "1-fuu", ActiveRecord::Type::Integer.new)
           result = @connection.exec_query(
-                                          'SELECT id, data FROM ex WHERE id = $1', nil, [[column, '1-fuu']])
+                                          'SELECT id, data FROM ex WHERE id = $1', nil, [bind])
 
           assert_equal 1, result.rows.length
           assert_equal 2, result.columns.length
 
-          assert_equal [['1', 'foo']], result.rows
+          assert_equal [[1, 'foo']], result.rows
         end
       end
 
@@ -437,10 +450,10 @@ module ActiveRecord
 
       private
       def insert(ctx, data)
-        binds   = data.map { |name, value|
-          [ctx.columns('ex').find { |x| x.name == name }, value]
+        binds = data.map { |name, value|
+          bind_param(value, name)
         }
-        columns = binds.map(&:first).map(&:name)
+        columns = binds.map(&:name)
 
         bind_subs = columns.length.times.map { |x| "$#{x + 1}" }
 
@@ -457,6 +470,10 @@ module ActiveRecord
       def connection_without_insert_returning
         ActiveRecord::Base.postgresql_connection(ActiveRecord::Base.configurations['arunit'].merge(:insert_returning => false))
       end
+
+      def bind_param(value, name = nil)
+        ActiveRecord::Relation::QueryAttribute.new(name, value, ActiveRecord::Type::Value.new)
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/quoting_test.rb b/activerecord/test/cases/adapters/postgresql/quoting_test.rb
index 894cf1ffa2..5e6f4dbbb8 100644
--- a/activerecord/test/cases/adapters/postgresql/quoting_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/quoting_test.rb
@@ -4,7 +4,7 @@ require 'ipaddr'
 module ActiveRecord
   module ConnectionAdapters
     class PostgreSQLAdapter
-      class QuotingTest < ActiveRecord::TestCase
+      class QuotingTest < ActiveRecord::PostgreSQLTestCase
         def setup
           @conn = ActiveRecord::Base.connection
         end
@@ -27,21 +27,16 @@ module ActiveRecord
           assert_equal "'Infinity'", @conn.quote(infinity)
         end
 
-        def test_quote_time_usec
-          assert_equal "'1970-01-01 00:00:00.000000'", @conn.quote(Time.at(0))
-          assert_equal "'1970-01-01 00:00:00.000000'", @conn.quote(Time.at(0).to_datetime)
-        end
-
         def test_quote_range
           range = "1,2]'; SELECT * FROM users; --".."a"
           type = OID::Range.new(Type::Integer.new, :int8range)
-          assert_equal "'[1,0]'", @conn.quote(type.type_cast_for_database(range))
+          assert_equal "'[1,0]'", @conn.quote(type.serialize(range))
         end
 
         def test_quote_bit_string
           value = "'); SELECT * FROM users; /*\n01\n*/--"
           type = OID::Bit.new
-          assert_equal nil, @conn.quote(type.type_cast_for_database(value))
+          assert_equal nil, @conn.quote(type.serialize(value))
         end
       end
     end
diff --git a/activerecord/test/cases/adapters/postgresql/range_test.rb b/activerecord/test/cases/adapters/postgresql/range_test.rb
index 70cf21100a..02b1083430 100644
--- a/activerecord/test/cases/adapters/postgresql/range_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/range_test.rb
@@ -1,13 +1,13 @@
 require "cases/helper"
 require 'support/connection_helper'
 
-if ActiveRecord::Base.connection.supports_ranges?
+if ActiveRecord::Base.connection.respond_to?(:supports_ranges?) && ActiveRecord::Base.connection.supports_ranges?
   class PostgresqlRange < ActiveRecord::Base
     self.table_name = "postgresql_ranges"
   end
 
-  class PostgresqlRangeTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+  class PostgresqlRangeTest < ActiveRecord::PostgreSQLTestCase
+    self.use_transactional_tests = false
     include ConnectionHelper
 
     def setup
@@ -91,7 +91,7 @@ _SQL
     end
 
     teardown do
-      @connection.execute 'DROP TABLE IF EXISTS postgresql_ranges'
+      @connection.drop_table 'postgresql_ranges', if_exists: true
       @connection.execute 'DROP TYPE IF EXISTS floatrange'
       reset_connection
     end
diff --git a/activerecord/test/cases/adapters/postgresql/referential_integrity_test.rb b/activerecord/test/cases/adapters/postgresql/referential_integrity_test.rb
new file mode 100644
index 0000000000..c895ab9db5
--- /dev/null
+++ b/activerecord/test/cases/adapters/postgresql/referential_integrity_test.rb
@@ -0,0 +1,111 @@
+require 'cases/helper'
+require 'support/connection_helper'
+
+class PostgreSQLReferentialIntegrityTest < ActiveRecord::PostgreSQLTestCase
+  self.use_transactional_tests = false
+
+  include ConnectionHelper
+
+  IS_REFERENTIAL_INTEGRITY_SQL = lambda do |sql|
+    sql.match(/DISABLE TRIGGER ALL/) || sql.match(/ENABLE TRIGGER ALL/)
+  end
+
+  module MissingSuperuserPrivileges
+    def execute(sql)
+      if IS_REFERENTIAL_INTEGRITY_SQL.call(sql)
+        super "BROKEN;" rescue nil # put transaction in broken state
+        raise ActiveRecord::StatementInvalid, 'PG::InsufficientPrivilege'
+      else
+        super
+      end
+    end
+  end
+
+  module ProgrammerMistake
+    def execute(sql)
+      if IS_REFERENTIAL_INTEGRITY_SQL.call(sql)
+        raise ArgumentError, 'something is not right.'
+      else
+        super
+      end
+    end
+  end
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+  end
+
+  def teardown
+    reset_connection
+    if ActiveRecord::Base.connection.is_a?(MissingSuperuserPrivileges)
+      raise "MissingSuperuserPrivileges patch was not removed"
+    end
+  end
+
+  def test_should_reraise_invalid_foreign_key_exception_and_show_warning
+    @connection.extend MissingSuperuserPrivileges
+
+    warning = capture(:stderr) do
+      e = assert_raises(ActiveRecord::InvalidForeignKey) do
+        @connection.disable_referential_integrity do
+          raise ActiveRecord::InvalidForeignKey, 'Should be re-raised'
+        end
+      end
+      assert_equal 'Should be re-raised', e.message
+    end
+    assert_match (/WARNING: Rails was not able to disable referential integrity/), warning
+    assert_match (/cause: PG::InsufficientPrivilege/), warning
+  end
+
+  def test_does_not_print_warning_if_no_invalid_foreign_key_exception_was_raised
+    @connection.extend MissingSuperuserPrivileges
+
+    warning = capture(:stderr) do
+      e = assert_raises(ActiveRecord::StatementInvalid) do
+        @connection.disable_referential_integrity do
+          raise ActiveRecord::StatementInvalid, 'Should be re-raised'
+        end
+      end
+      assert_equal 'Should be re-raised', e.message
+    end
+    assert warning.blank?, "expected no warnings but got:\n#{warning}"
+  end
+
+  def test_does_not_break_transactions
+    @connection.extend MissingSuperuserPrivileges
+
+    @connection.transaction do
+      @connection.disable_referential_integrity do
+        assert_transaction_is_not_broken
+      end
+      assert_transaction_is_not_broken
+    end
+  end
+
+  def test_does_not_break_nested_transactions
+    @connection.extend MissingSuperuserPrivileges
+
+    @connection.transaction do
+      @connection.transaction(requires_new: true) do
+        @connection.disable_referential_integrity do
+          assert_transaction_is_not_broken
+        end
+      end
+      assert_transaction_is_not_broken
+    end
+  end
+
+  def test_only_catch_active_record_errors_others_bubble_up
+    @connection.extend ProgrammerMistake
+
+    assert_raises ArgumentError do
+      @connection.disable_referential_integrity {}
+    end
+  end
+
+  private
+
+  def assert_transaction_is_not_broken
+    assert_equal 1, @connection.select_value("SELECT 1")
+  end
+end
diff --git a/activerecord/test/cases/adapters/postgresql/rename_table_test.rb b/activerecord/test/cases/adapters/postgresql/rename_table_test.rb
index 056a035622..bd64bae308 100644
--- a/activerecord/test/cases/adapters/postgresql/rename_table_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/rename_table_test.rb
@@ -1,14 +1,14 @@
 require "cases/helper"
 
-class PostgresqlRenameTableTest < ActiveRecord::TestCase
+class PostgresqlRenameTableTest < ActiveRecord::PostgreSQLTestCase
   def setup
     @connection = ActiveRecord::Base.connection
     @connection.create_table :before_rename, force: true
   end
 
   def teardown
-    @connection.execute 'DROP TABLE IF EXISTS "before_rename"'
-    @connection.execute 'DROP TABLE IF EXISTS "after_rename"'
+    @connection.drop_table "before_rename", if_exists: true
+    @connection.drop_table "after_rename", if_exists: true
   end
 
   test "renaming a table also renames the primary key index" do
diff --git a/activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb b/activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb
index 99c26c4bf7..a0afd922b2 100644
--- a/activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb
@@ -3,8 +3,8 @@ require "cases/helper"
 class SchemaThing < ActiveRecord::Base
 end
 
-class SchemaAuthorizationTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+class SchemaAuthorizationTest < ActiveRecord::PostgreSQLTestCase
+  self.use_transactional_tests = false
 
   TABLE_NAME = 'schema_things'
   COLUMNS = [
@@ -31,7 +31,7 @@ class SchemaAuthorizationTest < ActiveRecord::TestCase
     set_session_auth
     @connection.execute "RESET search_path"
     USERS.each do |u|
-      @connection.execute "DROP SCHEMA #{u} CASCADE"
+      @connection.drop_schema u
       @connection.execute "DROP USER #{u}"
     end
   end
@@ -55,7 +55,7 @@ class SchemaAuthorizationTest < ActiveRecord::TestCase
       set_session_auth
       USERS.each do |u|
         set_session_auth u
-        assert_equal u, @connection.exec_query("SELECT name FROM #{TABLE_NAME} WHERE id = $1", 'SQL', [[nil, 1]]).first['name']
+        assert_equal u, @connection.exec_query("SELECT name FROM #{TABLE_NAME} WHERE id = $1", 'SQL', [bind_param(1)]).first['name']
         set_session_auth
       end
     end
@@ -67,7 +67,7 @@ class SchemaAuthorizationTest < ActiveRecord::TestCase
       USERS.each do |u|
         @connection.clear_cache!
         set_session_auth u
-        assert_equal u, @connection.exec_query("SELECT name FROM #{TABLE_NAME} WHERE id = $1", 'SQL', [[nil, 1]]).first['name']
+        assert_equal u, @connection.exec_query("SELECT name FROM #{TABLE_NAME} WHERE id = $1", 'SQL', [bind_param(1)]).first['name']
         set_session_auth
       end
     end
@@ -111,4 +111,7 @@ class SchemaAuthorizationTest < ActiveRecord::TestCase
        @connection.session_auth =  auth || 'default'
     end
 
+    def bind_param(value)
+      ActiveRecord::Relation::QueryAttribute.new(nil, value, ActiveRecord::Type::Value.new)
+    end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/schema_test.rb b/activerecord/test/cases/adapters/postgresql/schema_test.rb
index e99f1e2867..93e98ec872 100644
--- a/activerecord/test/cases/adapters/postgresql/schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/schema_test.rb
@@ -2,8 +2,20 @@ require "cases/helper"
 require 'models/default'
 require 'support/schema_dumping_helper'
 
-class SchemaTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+module PGSchemaHelper
+  def with_schema_search_path(schema_search_path)
+    @connection.schema_search_path = schema_search_path
+    @connection.schema_cache.clear!
+    yield if block_given?
+  ensure
+    @connection.schema_search_path = "'$user', public"
+    @connection.schema_cache.clear!
+  end
+end
+
+class SchemaTest < ActiveRecord::PostgreSQLTestCase
+  include PGSchemaHelper
+  self.use_transactional_tests = false
 
   SCHEMA_NAME = 'test_schema'
   SCHEMA2_NAME = 'test_schema2'
@@ -84,8 +96,8 @@ class SchemaTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute "DROP SCHEMA #{SCHEMA2_NAME} CASCADE"
-    @connection.execute "DROP SCHEMA #{SCHEMA_NAME} CASCADE"
+    @connection.drop_schema SCHEMA2_NAME, if_exists: true
+    @connection.drop_schema SCHEMA_NAME, if_exists: true
   end
 
   def test_schema_names
@@ -121,10 +133,17 @@ class SchemaTest < ActiveRecord::TestCase
     assert !@connection.schema_names.include?("test_schema3")
   end
 
+  def test_drop_schema_if_exists
+    @connection.create_schema "some_schema"
+    assert_includes @connection.schema_names, "some_schema"
+    @connection.drop_schema "some_schema", if_exists: true
+    assert_not_includes @connection.schema_names, "some_schema"
+  end
+
   def test_habtm_table_name_with_schema
+    ActiveRecord::Base.connection.drop_schema "music", if_exists: true
+    ActiveRecord::Base.connection.create_schema "music"
     ActiveRecord::Base.connection.execute <<-SQL
-      DROP SCHEMA IF EXISTS music CASCADE;
-      CREATE SCHEMA music;
       CREATE TABLE music.albums (id serial primary key);
       CREATE TABLE music.songs (id serial primary key);
       CREATE TABLE music.albums_songs (album_id integer, song_id integer);
@@ -134,27 +153,31 @@ class SchemaTest < ActiveRecord::TestCase
     Album.create
     assert_equal song, Song.includes(:albums).references(:albums).first
   ensure
-    ActiveRecord::Base.connection.execute "DROP SCHEMA music CASCADE;"
+    ActiveRecord::Base.connection.drop_schema "music", if_exists: true
   end
 
-  def test_raise_drop_schema_with_nonexisting_schema
+  def test_drop_schema_with_nonexisting_schema
     assert_raises(ActiveRecord::StatementInvalid) do
-      @connection.drop_schema "test_schema3"
+      @connection.drop_schema "idontexist"
+    end
+
+    assert_nothing_raised do
+      @connection.drop_schema "idontexist", if_exists: true
     end
   end
 
   def test_raise_wraped_exception_on_bad_prepare
     assert_raises(ActiveRecord::StatementInvalid) do
-      @connection.exec_query "select * from developers where id = ?", 'sql', [[nil, 1]]
+      @connection.exec_query "select * from developers where id = ?", 'sql', [bind_param(1)]
     end
   end
 
   def test_schema_change_with_prepared_stmt
     altered = false
-    @connection.exec_query "select * from developers where id = $1", 'sql', [[nil, 1]]
+    @connection.exec_query "select * from developers where id = $1", 'sql', [bind_param(1)]
     @connection.exec_query "alter table developers add column zomg int", 'sql', []
     altered = true
-    @connection.exec_query "select * from developers where id = $1", 'sql', [[nil, 1]]
+    @connection.exec_query "select * from developers where id = $1", 'sql', [bind_param(1)]
   ensure
     # We are not using DROP COLUMN IF EXISTS because that syntax is only
     # supported by pg 9.X
@@ -300,11 +323,11 @@ class SchemaTest < ActiveRecord::TestCase
 
   def test_with_uppercase_index_name
     @connection.execute "CREATE INDEX \"things_Index\" ON #{SCHEMA_NAME}.things (name)"
-    assert_nothing_raised { @connection.remove_index! "things", "#{SCHEMA_NAME}.things_Index"}
+    assert_nothing_raised { @connection.remove_index "things", name: "#{SCHEMA_NAME}.things_Index"}
     @connection.execute "CREATE INDEX \"things_Index\" ON #{SCHEMA_NAME}.things (name)"
 
     with_schema_search_path SCHEMA_NAME do
-      assert_nothing_raised { @connection.remove_index! "things", "things_Index"}
+      assert_nothing_raised { @connection.remove_index "things", name: "things_Index"}
     end
   end
 
@@ -384,16 +407,16 @@ class SchemaTest < ActiveRecord::TestCase
   def test_reset_pk_sequence
     sequence_name = "#{SCHEMA_NAME}.#{UNMATCHED_SEQUENCE_NAME}"
     @connection.execute "SELECT setval('#{sequence_name}', 123)"
-    assert_equal "124", @connection.select_value("SELECT nextval('#{sequence_name}')")
+    assert_equal 124, @connection.select_value("SELECT nextval('#{sequence_name}')")
     @connection.reset_pk_sequence!("#{SCHEMA_NAME}.#{UNMATCHED_PK_TABLE_NAME}")
-    assert_equal "1", @connection.select_value("SELECT nextval('#{sequence_name}')")
+    assert_equal 1, @connection.select_value("SELECT nextval('#{sequence_name}')")
   end
 
   def test_set_pk_sequence
     table_name = "#{SCHEMA_NAME}.#{PK_TABLE_NAME}"
     _, sequence_name = @connection.pk_and_sequence_for table_name
     @connection.set_pk_sequence! table_name, 123
-    assert_equal "124", @connection.select_value("SELECT nextval('#{sequence_name}')")
+    assert_equal 124, @connection.select_value("SELECT nextval('#{sequence_name}')")
     @connection.reset_pk_sequence! table_name
   end
 
@@ -404,13 +427,6 @@ class SchemaTest < ActiveRecord::TestCase
       end
     end
 
-    def with_schema_search_path(schema_search_path)
-      @connection.schema_search_path = schema_search_path
-      yield if block_given?
-    ensure
-      @connection.schema_search_path = "'$user', public"
-    end
-
     def do_dump_index_tests_for_schema(this_schema_name, first_index_column_name, second_index_column_name, third_index_column_name, fourth_index_column_name)
       with_schema_search_path(this_schema_name) do
         indexes = @connection.indexes(TABLE_NAME).sort_by(&:name)
@@ -435,9 +451,13 @@ class SchemaTest < ActiveRecord::TestCase
       assert_equal this_index_column, this_index.columns[0]
       assert_equal this_index_name, this_index.name
     end
+
+    def bind_param(value)
+      ActiveRecord::Relation::QueryAttribute.new(nil, value, ActiveRecord::Type::Value.new)
+    end
 end
 
-class SchemaForeignKeyTest < ActiveRecord::TestCase
+class SchemaForeignKeyTest < ActiveRecord::PostgreSQLTestCase
   include SchemaDumpingHelper
 
   setup do
@@ -454,18 +474,18 @@ class SchemaForeignKeyTest < ActiveRecord::TestCase
     end
     @connection.add_foreign_key "wagons", "my_schema.trains", column: "train_id"
     output = dump_table_schema "wagons"
-    assert_match %r{\s+add_foreign_key "wagons", "my_schema.trains", column: "train_id"$}, output
+    assert_match %r{\s+add_foreign_key "wagons", "my_schema\.trains", column: "train_id"$}, output
   ensure
-    @connection.execute "DROP TABLE IF EXISTS wagons"
-    @connection.execute "DROP TABLE IF EXISTS my_schema.trains"
-    @connection.execute "DROP SCHEMA IF EXISTS my_schema"
+    @connection.drop_table "wagons", if_exists: true
+    @connection.drop_table "my_schema.trains", if_exists: true
+    @connection.drop_schema "my_schema", if_exists: true
   end
 end
 
-class DefaultsUsingMultipleSchemasAndDomainTest < ActiveSupport::TestCase
+class DefaultsUsingMultipleSchemasAndDomainTest < ActiveRecord::PostgreSQLTestCase
   setup do
     @connection = ActiveRecord::Base.connection
-    @connection.execute "DROP SCHEMA IF EXISTS schema_1 CASCADE"
+    @connection.drop_schema "schema_1", if_exists: true
     @connection.execute "CREATE SCHEMA schema_1"
     @connection.execute "CREATE DOMAIN schema_1.text AS text"
     @connection.execute "CREATE DOMAIN schema_1.varchar AS varchar"
@@ -476,13 +496,14 @@ class DefaultsUsingMultipleSchemasAndDomainTest < ActiveSupport::TestCase
     @connection.create_table "defaults" do |t|
       t.text "text_col", default: "some value"
       t.string "string_col", default: "some value"
+      t.decimal "decimal_col", default: "3.14159265358979323846"
     end
     Default.reset_column_information
   end
 
   teardown do
     @connection.schema_search_path = @old_search_path
-    @connection.execute "DROP SCHEMA IF EXISTS schema_1 CASCADE"
+    @connection.drop_schema "schema_1", if_exists: true
     Default.reset_column_information
   end
 
@@ -494,6 +515,10 @@ class DefaultsUsingMultipleSchemasAndDomainTest < ActiveSupport::TestCase
     assert_equal "some value", Default.new.string_col, "Default of string column was not correctly parsed"
   end
 
+  def test_decimal_defaults_in_new_schema_when_overriding_domain
+    assert_equal BigDecimal.new("3.14159265358979323846"), Default.new.decimal_col, "Default of decimal column was not correctly parsed"
+  end
+
   def test_bpchar_defaults_in_new_schema_when_overriding_domain
     @connection.execute "ALTER TABLE defaults ADD bpchar_col bpchar DEFAULT 'some value'"
     Default.reset_column_information
@@ -510,3 +535,40 @@ class DefaultsUsingMultipleSchemasAndDomainTest < ActiveSupport::TestCase
     assert_equal "foo'::bar", Default.new.string_col
   end
 end
+
+class SchemaWithDotsTest < ActiveRecord::PostgreSQLTestCase
+  include PGSchemaHelper
+  self.use_transactional_tests = false
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_schema "my.schema"
+  end
+
+  teardown do
+    @connection.drop_schema "my.schema", if_exists: true
+  end
+
+  test "rename_table" do
+    with_schema_search_path('"my.schema"') do
+      @connection.create_table :posts
+      @connection.rename_table :posts, :articles
+      assert_equal ["articles"], @connection.tables
+    end
+  end
+
+  test "Active Record basics" do
+    with_schema_search_path('"my.schema"') do
+      @connection.create_table :articles do |t|
+        t.string :title
+      end
+      article_class = Class.new(ActiveRecord::Base) do
+        self.table_name = '"my.schema".articles'
+      end
+
+      article_class.create!(title: "zOMG, welcome to my blorgh!")
+      welcome_article = article_class.last
+      assert_equal "zOMG, welcome to my blorgh!", welcome_article.title
+    end
+  end
+end
diff --git a/activerecord/test/cases/adapters/postgresql/serial_test.rb b/activerecord/test/cases/adapters/postgresql/serial_test.rb
new file mode 100644
index 0000000000..7d30db247b
--- /dev/null
+++ b/activerecord/test/cases/adapters/postgresql/serial_test.rb
@@ -0,0 +1,60 @@
+require "cases/helper"
+require 'support/schema_dumping_helper'
+
+class PostgresqlSerialTest < ActiveRecord::PostgreSQLTestCase
+  include SchemaDumpingHelper
+
+  class PostgresqlSerial < ActiveRecord::Base; end
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table "postgresql_serials", force: true do |t|
+      t.serial :seq
+    end
+  end
+
+  teardown do
+    @connection.drop_table "postgresql_serials", if_exists: true
+  end
+
+  def test_serial_column
+    column = PostgresqlSerial.columns_hash["seq"]
+    assert_equal :integer, column.type
+    assert_equal "integer", column.sql_type
+    assert column.serial?
+  end
+
+  def test_schema_dump_with_shorthand
+    output = dump_table_schema "postgresql_serials"
+    assert_match %r{t\.serial\s+"seq"}, output
+  end
+end
+
+class PostgresqlBigSerialTest < ActiveRecord::PostgreSQLTestCase
+  include SchemaDumpingHelper
+
+  class PostgresqlBigSerial < ActiveRecord::Base; end
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table "postgresql_big_serials", force: true do |t|
+      t.bigserial :seq
+    end
+  end
+
+  teardown do
+    @connection.drop_table "postgresql_big_serials", if_exists: true
+  end
+
+  def test_bigserial_column
+    column = PostgresqlBigSerial.columns_hash["seq"]
+    assert_equal :integer, column.type
+    assert_equal "bigint", column.sql_type
+    assert column.serial?
+  end
+
+  def test_schema_dump_with_shorthand
+    output = dump_table_schema "postgresql_big_serials"
+    assert_match %r{t\.bigserial\s+"seq"}, output
+  end
+end
diff --git a/activerecord/test/cases/adapters/postgresql/statement_pool_test.rb b/activerecord/test/cases/adapters/postgresql/statement_pool_test.rb
index 1497b0abc7..5aab246c99 100644
--- a/activerecord/test/cases/adapters/postgresql/statement_pool_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/statement_pool_test.rb
@@ -13,7 +13,7 @@ module ActiveRecord
         end
       end
 
-      class StatementPoolTest < ActiveRecord::TestCase
+      class StatementPoolTest < ActiveRecord::PostgreSQLTestCase
         if Process.respond_to?(:fork)
           def test_cache_is_per_pid
             cache = StatementPool.new nil, 10
diff --git a/activerecord/test/cases/adapters/postgresql/timestamp_test.rb b/activerecord/test/cases/adapters/postgresql/timestamp_test.rb
index eb32c4d2c2..4c4866b46b 100644
--- a/activerecord/test/cases/adapters/postgresql/timestamp_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/timestamp_test.rb
@@ -2,10 +2,10 @@ require 'cases/helper'
 require 'models/developer'
 require 'models/topic'
 
-class PostgresqlTimestampTest < ActiveRecord::TestCase
+class PostgresqlTimestampTest < ActiveRecord::PostgreSQLTestCase
   class PostgresqlTimestampWithZone < ActiveRecord::Base; end
 
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   setup do
     @connection = ActiveRecord::Base.connection
@@ -43,7 +43,7 @@ class PostgresqlTimestampTest < ActiveRecord::TestCase
   end
 end
 
-class TimestampTest < ActiveRecord::TestCase
+class PostgresqlTimestampFixtureTest < ActiveRecord::PostgreSQLTestCase
   fixtures :topics
 
   def test_group_by_date
@@ -70,53 +70,6 @@ class TimestampTest < ActiveRecord::TestCase
     assert_equal(-1.0 / 0.0, d.updated_at)
   end
 
-  def test_default_datetime_precision
-    ActiveRecord::Base.connection.create_table(:foos)
-    ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime
-    ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime
-    assert_nil activerecord_column_option('foos', 'created_at', 'precision')
-  end
-
-  def test_timestamp_data_type_with_precision
-    ActiveRecord::Base.connection.create_table(:foos)
-    ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime, :precision => 0
-    ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime, :precision => 5
-    assert_equal 0, activerecord_column_option('foos', 'created_at', 'precision')
-    assert_equal 5, activerecord_column_option('foos', 'updated_at', 'precision')
-  end
-
-  def test_timestamps_helper_with_custom_precision
-    ActiveRecord::Base.connection.create_table(:foos) do |t|
-      t.timestamps :null => true, :precision => 4
-    end
-    assert_equal 4, activerecord_column_option('foos', 'created_at', 'precision')
-    assert_equal 4, activerecord_column_option('foos', 'updated_at', 'precision')
-  end
-
-  def test_passing_precision_to_timestamp_does_not_set_limit
-    ActiveRecord::Base.connection.create_table(:foos) do |t|
-      t.timestamps :null => true, :precision => 4
-    end
-    assert_nil activerecord_column_option("foos", "created_at", "limit")
-    assert_nil activerecord_column_option("foos", "updated_at", "limit")
-  end
-
-  def test_invalid_timestamp_precision_raises_error
-    assert_raises ActiveRecord::ActiveRecordError do
-      ActiveRecord::Base.connection.create_table(:foos) do |t|
-        t.timestamps :null => true, :precision => 7
-      end
-    end
-  end
-
-  def test_postgres_agrees_with_activerecord_about_precision
-    ActiveRecord::Base.connection.create_table(:foos) do |t|
-      t.timestamps :null => true, :precision => 4
-    end
-    assert_equal '4', pg_datetime_precision('foos', 'created_at')
-    assert_equal '4', pg_datetime_precision('foos', 'updated_at')
-  end
-
   def test_bc_timestamp
     date = Date.new(0) - 1.week
     Developer.create!(:name => "aaron", :updated_at => date)
@@ -134,21 +87,4 @@ class TimestampTest < ActiveRecord::TestCase
     Developer.create!(:name => "yahagi", :updated_at => date)
     assert_equal date, Developer.find_by_name("yahagi").updated_at
   end
-
-  private
-
-  def pg_datetime_precision(table_name, column_name)
-    results = ActiveRecord::Base.connection.execute("SELECT column_name, datetime_precision FROM information_schema.columns WHERE table_name ='#{table_name}'")
-    result = results.find do |result_hash|
-      result_hash["column_name"] == column_name
-    end
-    result && result["datetime_precision"]
-  end
-
-  def activerecord_column_option(tablename, column_name, option)
-    result = ActiveRecord::Base.connection.columns(tablename).find do |column|
-      column.name == column_name
-    end
-    result && result.send(option)
-  end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/type_lookup_test.rb b/activerecord/test/cases/adapters/postgresql/type_lookup_test.rb
index c88259d274..77a99ca778 100644
--- a/activerecord/test/cases/adapters/postgresql/type_lookup_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/type_lookup_test.rb
@@ -1,6 +1,6 @@
 require 'cases/helper'
 
-class PostgresqlTypeLookupTest < ActiveRecord::TestCase
+class PostgresqlTypeLookupTest < ActiveRecord::PostgreSQLTestCase
   setup do
     @connection = ActiveRecord::Base.connection
   end
@@ -18,8 +18,8 @@ class PostgresqlTypeLookupTest < ActiveRecord::TestCase
     bigint_array = @connection.type_map.lookup(1016, -1, "bigint[]")
     big_array = [123456789123456789]
 
-    assert_raises(RangeError) { int_array.type_cast_from_user(big_array) }
-    assert_equal big_array, bigint_array.type_cast_from_user(big_array)
+    assert_raises(RangeError) { int_array.serialize(big_array) }
+    assert_equal "{123456789123456789}", bigint_array.serialize(big_array)
   end
 
   test "range types correctly respect registration of subtypes" do
@@ -27,7 +27,7 @@ class PostgresqlTypeLookupTest < ActiveRecord::TestCase
     bigint_range = @connection.type_map.lookup(3926, -1, "int8range")
     big_range = 0..123456789123456789
 
-    assert_raises(RangeError) { int_range.type_cast_for_database(big_range) }
-    assert_equal "[0,123456789123456789]", bigint_range.type_cast_for_database(big_range)
+    assert_raises(RangeError) { int_range.serialize(big_range) }
+    assert_equal "[0,123456789123456789]", bigint_range.serialize(big_range)
   end
 end
diff --git a/activerecord/test/cases/adapters/postgresql/utils_test.rb b/activerecord/test/cases/adapters/postgresql/utils_test.rb
index 3fdb6888d9..095c1826e5 100644
--- a/activerecord/test/cases/adapters/postgresql/utils_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/utils_test.rb
@@ -1,6 +1,7 @@
 require 'cases/helper'
+require 'active_record/connection_adapters/postgresql/utils'
 
-class PostgreSQLUtilsTest < ActiveSupport::TestCase
+class PostgreSQLUtilsTest < ActiveRecord::PostgreSQLTestCase
   Name = ActiveRecord::ConnectionAdapters::PostgreSQL::Name
   include ActiveRecord::ConnectionAdapters::PostgreSQL::Utils
 
@@ -20,7 +21,7 @@ class PostgreSQLUtilsTest < ActiveSupport::TestCase
   end
 end
 
-class PostgreSQLNameTest < ActiveSupport::TestCase
+class PostgreSQLNameTest < ActiveRecord::PostgreSQLTestCase
   Name = ActiveRecord::ConnectionAdapters::PostgreSQL::Name
 
   test "represents itself as schema.name" do
diff --git a/activerecord/test/cases/adapters/postgresql/uuid_test.rb b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
index 7d2fae69d5..7127d69e9e 100644
--- a/activerecord/test/cases/adapters/postgresql/uuid_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
@@ -8,11 +7,11 @@ module PostgresqlUUIDHelper
   end
 
   def drop_table(name)
-    connection.execute "drop table if exists #{name}"
+    connection.drop_table name, if_exists: true
   end
 end
 
-class PostgresqlUUIDTest < ActiveRecord::TestCase
+class PostgresqlUUIDTest < ActiveRecord::PostgreSQLTestCase
   include PostgresqlUUIDHelper
   include SchemaDumpingHelper
 
@@ -49,9 +48,10 @@ class PostgresqlUUIDTest < ActiveRecord::TestCase
     column = UUIDType.columns_hash["guid"]
     assert_equal :uuid, column.type
     assert_equal "uuid", column.sql_type
-    assert_not column.number?
-    assert_not column.binary?
     assert_not column.array?
+
+    type = UUIDType.type_for_attribute("guid")
+    assert_not type.binary?
   end
 
   def test_treat_blank_uuid_as_nil
@@ -114,7 +114,7 @@ class PostgresqlUUIDTest < ActiveRecord::TestCase
 
   def test_schema_dump_with_shorthand
     output = dump_table_schema "uuid_data_type"
-    assert_match %r{t.uuid "guid"}, output
+    assert_match %r{t\.uuid "guid"}, output
   end
 
   def test_uniqueness_validation_ignores_uuid
@@ -135,27 +135,7 @@ class PostgresqlUUIDTest < ActiveRecord::TestCase
   end
 end
 
-class PostgresqlLargeKeysTest < ActiveRecord::TestCase
-  include PostgresqlUUIDHelper
-  include SchemaDumpingHelper
-
-  def setup
-    connection.create_table('big_serials', id: :bigserial) do |t|
-      t.string 'name'
-    end
-  end
-
-  def test_omg
-    schema = dump_table_schema "big_serials"
-    assert_match "create_table \"big_serials\", id: :bigserial", schema
-  end
-
-  def teardown
-    drop_table "big_serials"
-  end
-end
-
-class PostgresqlUUIDGenerationTest < ActiveRecord::TestCase
+class PostgresqlUUIDGenerationTest < ActiveRecord::PostgreSQLTestCase
   include PostgresqlUUIDHelper
   include SchemaDumpingHelper
 
@@ -230,7 +210,7 @@ class PostgresqlUUIDGenerationTest < ActiveRecord::TestCase
   end
 end
 
-class PostgresqlUUIDTestNilDefault < ActiveRecord::TestCase
+class PostgresqlUUIDTestNilDefault < ActiveRecord::PostgreSQLTestCase
   include PostgresqlUUIDHelper
   include SchemaDumpingHelper
 
@@ -264,7 +244,7 @@ class PostgresqlUUIDTestNilDefault < ActiveRecord::TestCase
   end
 end
 
-class PostgresqlUUIDTestInverseOf < ActiveRecord::TestCase
+class PostgresqlUUIDTestInverseOf < ActiveRecord::PostgreSQLTestCase
   include PostgresqlUUIDHelper
 
   class UuidPost < ActiveRecord::Base
diff --git a/activerecord/test/cases/adapters/postgresql/view_test.rb b/activerecord/test/cases/adapters/postgresql/view_test.rb
deleted file mode 100644
index 8a8e1d3b17..0000000000
--- a/activerecord/test/cases/adapters/postgresql/view_test.rb
+++ /dev/null
@@ -1,63 +0,0 @@
-require "cases/helper"
-require "cases/view_test"
-
-class UpdateableViewTest < ActiveRecord::TestCase
-  fixtures :books
-
-  class PrintedBook < ActiveRecord::Base
-    self.primary_key = "id"
-  end
-
-  setup do
-    @connection = ActiveRecord::Base.connection
-    @connection.execute <<-SQL
-      CREATE VIEW printed_books
-        AS SELECT id, name, status, format FROM books WHERE format = 'paperback'
-    SQL
-  end
-
-  teardown do
-    @connection.execute "DROP VIEW printed_books" if @connection.table_exists? "printed_books"
-  end
-
-  def test_update_record
-    book = PrintedBook.first
-    book.name = "AWDwR"
-    book.save!
-    book.reload
-    assert_equal "AWDwR", book.name
-  end
-
-  def test_insert_record
-    PrintedBook.create! name: "Rails in Action", status: 0, format: "paperback"
-
-    new_book = PrintedBook.last
-    assert_equal "Rails in Action", new_book.name
-  end
-
-  def test_update_record_to_fail_view_conditions
-    book = PrintedBook.first
-    book.format = "ebook"
-    book.save!
-
-    assert_raises ActiveRecord::RecordNotFound do
-      book.reload
-    end
-  end
-end
-
-if ActiveRecord::Base.connection.supports_materialized_views?
-class MaterializedViewTest < ActiveRecord::TestCase
-  include ViewBehavior
-
-  private
-  def create_view(name, query)
-    @connection.execute "CREATE MATERIALIZED VIEW #{name} AS #{query}"
-  end
-
-  def drop_view(name)
-    @connection.execute "DROP MATERIALIZED VIEW #{name}" if @connection.table_exists? name
-
-  end
-end
-end
diff --git a/activerecord/test/cases/adapters/postgresql/xml_test.rb b/activerecord/test/cases/adapters/postgresql/xml_test.rb
index 5aba118518..add32699fa 100644
--- a/activerecord/test/cases/adapters/postgresql/xml_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/xml_test.rb
@@ -1,8 +1,7 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'support/schema_dumping_helper'
 
-class PostgresqlXMLTest < ActiveRecord::TestCase
+class PostgresqlXMLTest < ActiveRecord::PostgreSQLTestCase
   include SchemaDumpingHelper
   class XmlDataType < ActiveRecord::Base
     self.table_name = 'xml_data_type'
@@ -23,7 +22,7 @@ class PostgresqlXMLTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute 'drop table if exists xml_data_type'
+    @connection.drop_table 'xml_data_type', if_exists: true
   end
 
   def test_column
@@ -50,6 +49,6 @@ class PostgresqlXMLTest < ActiveRecord::TestCase
 
   def test_schema_dump_with_shorthand
     output = dump_table_schema("xml_data_type")
-    assert_match %r{t.xml "payload"}, output
+    assert_match %r{t\.xml "payload"}, output
   end
 end
diff --git a/activerecord/test/cases/adapters/sqlite3/collation_test.rb b/activerecord/test/cases/adapters/sqlite3/collation_test.rb
new file mode 100644
index 0000000000..58a9469ce5
--- /dev/null
+++ b/activerecord/test/cases/adapters/sqlite3/collation_test.rb
@@ -0,0 +1,53 @@
+require "cases/helper"
+require 'support/schema_dumping_helper'
+
+class SQLite3CollationTest < ActiveRecord::SQLite3TestCase
+  include SchemaDumpingHelper
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table :collation_table_sqlite3, force: true do |t|
+      t.string :string_nocase, collation: 'NOCASE'
+      t.text :text_rtrim, collation: 'RTRIM'
+    end
+  end
+
+  def teardown
+    @connection.drop_table :collation_table_sqlite3, if_exists: true
+  end
+
+  test "string column with collation" do
+    column = @connection.columns(:collation_table_sqlite3).find { |c| c.name == 'string_nocase' }
+    assert_equal :string, column.type
+    assert_equal 'NOCASE', column.collation
+  end
+
+  test "text column with collation" do
+    column = @connection.columns(:collation_table_sqlite3).find { |c| c.name == 'text_rtrim' }
+    assert_equal :text, column.type
+    assert_equal 'RTRIM', column.collation
+  end
+
+  test "add column with collation" do
+    @connection.add_column :collation_table_sqlite3, :title, :string, collation: 'RTRIM'
+
+    column = @connection.columns(:collation_table_sqlite3).find { |c| c.name == 'title' }
+    assert_equal :string, column.type
+    assert_equal 'RTRIM', column.collation
+  end
+
+  test "change column with collation" do
+    @connection.add_column :collation_table_sqlite3, :description, :string
+    @connection.change_column :collation_table_sqlite3, :description, :text, collation: 'RTRIM'
+
+    column = @connection.columns(:collation_table_sqlite3).find { |c| c.name == 'description' }
+    assert_equal :text, column.type
+    assert_equal 'RTRIM', column.collation
+  end
+
+  test "schema dump includes collation" do
+    output = dump_table_schema("collation_table_sqlite3")
+    assert_match %r{t.string\s+"string_nocase",\s+collation: "NOCASE"$}, output
+    assert_match %r{t.text\s+"text_rtrim",\s+collation: "RTRIM"$}, output
+  end
+end
diff --git a/activerecord/test/cases/adapters/sqlite3/copy_table_test.rb b/activerecord/test/cases/adapters/sqlite3/copy_table_test.rb
index 13b754d226..34e3b2e023 100644
--- a/activerecord/test/cases/adapters/sqlite3/copy_table_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/copy_table_test.rb
@@ -1,6 +1,6 @@
 require "cases/helper"
 
-class CopyTableTest < ActiveRecord::TestCase
+class CopyTableTest < ActiveRecord::SQLite3TestCase
   fixtures :customers
 
   def setup
diff --git a/activerecord/test/cases/adapters/sqlite3/explain_test.rb b/activerecord/test/cases/adapters/sqlite3/explain_test.rb
index 7d66c44798..2aec322582 100644
--- a/activerecord/test/cases/adapters/sqlite3/explain_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/explain_test.rb
@@ -5,7 +5,7 @@ require 'models/computer'
 module ActiveRecord
   module ConnectionAdapters
     class SQLite3Adapter
-      class ExplainTest < ActiveRecord::TestCase
+      class ExplainTest < ActiveRecord::SQLite3TestCase
         fixtures :developers
 
         def test_explain_for_one_query
diff --git a/activerecord/test/cases/adapters/sqlite3/quoting_test.rb b/activerecord/test/cases/adapters/sqlite3/quoting_test.rb
index 274e358e4a..87a892db37 100644
--- a/activerecord/test/cases/adapters/sqlite3/quoting_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/quoting_test.rb
@@ -6,7 +6,7 @@ require 'securerandom'
 module ActiveRecord
   module ConnectionAdapters
     class SQLite3Adapter
-      class QuotingTest < ActiveRecord::TestCase
+      class QuotingTest < ActiveRecord::SQLite3TestCase
         def setup
           @conn = Base.sqlite3_connection :database => ':memory:',
             :adapter => 'sqlite3',
@@ -85,9 +85,9 @@ module ActiveRecord
 
         def test_quoting_binary_strings
           value = "hello".encode('ascii-8bit')
-          type = SQLite3String.new
+          type = Type::String.new
 
-          assert_equal "'hello'", @conn.quote(type.type_cast_for_database(value))
+          assert_equal "'hello'", @conn.quote(type.serialize(value))
         end
       end
     end
diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
index 029663e7f4..640df31e2e 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/owner'
 require 'tempfile'
@@ -6,10 +5,10 @@ require 'support/ddl_helper'
 
 module ActiveRecord
   module ConnectionAdapters
-    class SQLite3AdapterTest < ActiveRecord::TestCase
+    class SQLite3AdapterTest < ActiveRecord::SQLite3TestCase
       include DdlHelper
 
-      self.use_transactional_fixtures = false
+      self.use_transactional_tests = false
 
       class DualEncoding < ActiveRecord::Base
       end
@@ -23,7 +22,7 @@ module ActiveRecord
       def test_bad_connection
         assert_raise ActiveRecord::NoDatabaseError do
           connection = ActiveRecord::Base.sqlite3_connection(adapter: "sqlite3", database: "/tmp/should/_not/_exist/-cinco-dog.db")
-          connection.exec_query('drop table if exists ex')
+          connection.drop_table 'ex', if_exists: true
         end
       end
 
@@ -83,8 +82,7 @@ module ActiveRecord
 
       def test_exec_insert
         with_example_table do
-          column = @conn.columns('ex').find { |col| col.name == 'number' }
-          vals   = [[column, 10]]
+          vals = [Relation::QueryAttribute.new("number", 10, Type::Value.new)]
           @conn.exec_insert('insert into ex (number) VALUES (?)', 'SQL', vals)
 
           result = @conn.exec_query(
@@ -157,7 +155,7 @@ module ActiveRecord
         with_example_table 'id int, data string' do
           @conn.exec_query('INSERT INTO ex (id, data) VALUES (1, "foo")')
           result = @conn.exec_query(
-            'SELECT id, data FROM ex WHERE id = ?', nil, [[nil, 1]])
+            'SELECT id, data FROM ex WHERE id = ?', nil, [Relation::QueryAttribute.new(nil, 1, Type::Value.new)])
 
           assert_equal 1, result.rows.length
           assert_equal 2, result.columns.length
@@ -169,10 +167,9 @@ module ActiveRecord
       def test_exec_query_typecasts_bind_vals
         with_example_table 'id int, data string' do
           @conn.exec_query('INSERT INTO ex (id, data) VALUES (1, "foo")')
-          column = @conn.columns('ex').find { |col| col.name == 'id' }
 
           result = @conn.exec_query(
-            'SELECT id, data FROM ex WHERE id = ?', nil, [[column, '1-fuu']])
+            'SELECT id, data FROM ex WHERE id = ?', nil, [Relation::QueryAttribute.new("id", "1-fuu", Type::Integer.new)])
 
           assert_equal 1, result.rows.length
           assert_equal 2, result.columns.length
@@ -194,7 +191,7 @@ module ActiveRecord
         binary.save!
         assert_equal str, binary.data
       ensure
-        DualEncoding.connection.execute('DROP TABLE IF EXISTS dual_encodings')
+        DualEncoding.connection.drop_table 'dual_encodings', if_exists: true
       end
 
       def test_type_cast_should_not_mutate_encoding
@@ -297,7 +294,7 @@ module ActiveRecord
       def test_tables_logs_name
         sql = <<-SQL
           SELECT name FROM sqlite_master
-          WHERE (type = 'table' OR type = 'view') AND NOT name = 'sqlite_sequence'
+          WHERE type IN ('table','view') AND name <> 'sqlite_sequence'
         SQL
         assert_logged [[sql.squish, 'SCHEMA', []]] do
           @conn.tables('hello')
@@ -316,8 +313,7 @@ module ActiveRecord
         with_example_table do
           sql = <<-SQL
             SELECT name FROM sqlite_master
-            WHERE (type = 'table' OR type = 'view')
-            AND NOT name = 'sqlite_sequence' AND name = \"ex\"
+            WHERE type IN ('table','view') AND name <> 'sqlite_sequence' AND name = 'ex'
           SQL
           assert_logged [[sql.squish, 'SCHEMA', []]] do
             assert @conn.table_exists?('ex')
@@ -424,17 +420,20 @@ module ActiveRecord
       end
 
       def test_statement_closed
-        db = SQLite3::Database.new(ActiveRecord::Base.
+        db = ::SQLite3::Database.new(ActiveRecord::Base.
                                    configurations['arunit']['database'])
-        statement = SQLite3::Statement.new(db,
+        statement = ::SQLite3::Statement.new(db,
                                            'CREATE TABLE statement_test (number integer not null)')
-        statement.stubs(:step).raises(SQLite3::BusyException, 'busy')
-        statement.stubs(:columns).once.returns([])
-        statement.expects(:close).once
-        SQLite3::Statement.stubs(:new).returns(statement)
-
-        assert_raises ActiveRecord::StatementInvalid do
-          @conn.exec_query 'select * from statement_test'
+        statement.stub(:step, ->{ raise ::SQLite3::BusyException.new('busy') }) do
+          assert_called(statement, :columns, returns: []) do
+            assert_called(statement, :close) do
+              ::SQLite3::Statement.stub(:new, statement) do
+                assert_raises ActiveRecord::StatementInvalid do
+                  @conn.exec_query 'select * from statement_test'
+                end
+              end
+            end
+          end
         end
       end
 
diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb
index f545fc2011..887dcfc96c 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb
@@ -1,10 +1,9 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/owner'
 
 module ActiveRecord
   module ConnectionAdapters
-    class SQLite3CreateFolder < ActiveRecord::TestCase
+    class SQLite3CreateFolder < ActiveRecord::SQLite3TestCase
       def test_sqlite_creates_directory
         Dir.mktmpdir do |dir|
           dir = Pathname.new(dir)
diff --git a/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb b/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb
index fd0044ac05..559b951109 100644
--- a/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb
@@ -2,11 +2,11 @@ require 'cases/helper'
 
 module ActiveRecord::ConnectionAdapters
   class SQLite3Adapter
-    class StatementPoolTest < ActiveRecord::TestCase
+    class StatementPoolTest < ActiveRecord::SQLite3TestCase
       if Process.respond_to?(:fork)
         def test_cache_is_per_pid
 
-          cache = StatementPool.new nil, 10
+          cache = StatementPool.new(10)
           cache['foo'] = 'bar'
           assert_equal 'bar', cache['foo']
 
@@ -22,4 +22,3 @@ module ActiveRecord::ConnectionAdapters
     end
   end
 end
-
diff --git a/activerecord/test/cases/ar_schema_test.rb b/activerecord/test/cases/ar_schema_test.rb
index f4e8003bc3..9d5327bf35 100644
--- a/activerecord/test/cases/ar_schema_test.rb
+++ b/activerecord/test/cases/ar_schema_test.rb
@@ -3,7 +3,7 @@ require "cases/helper"
 if ActiveRecord::Base.connection.supports_migrations?
 
   class ActiveRecordSchemaTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     setup do
       @original_verbose = ActiveRecord::Migration.verbose
diff --git a/activerecord/test/cases/associations/association_scope_test.rb b/activerecord/test/cases/associations/association_scope_test.rb
index 3e0032ec73..472e270f8c 100644
--- a/activerecord/test/cases/associations/association_scope_test.rb
+++ b/activerecord/test/cases/associations/association_scope_test.rb
@@ -8,12 +8,7 @@ module ActiveRecord
       test 'does not duplicate conditions' do
         scope = AssociationScope.scope(Author.new.association(:welcome_posts),
                                         Author.connection)
-        wheres = scope.where_values.map(&:right)
-        binds = scope.bind_values.map(&:last)
-        wheres = scope.where_values.map(&:right).reject { |node|
-          Arel::Nodes::BindParam === node
-        }
-        assert_equal wheres.uniq, wheres
+        binds = scope.where_clause.binds.map(&:value)
         assert_equal binds.uniq, binds
       end
     end
diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index 17394cb6f7..938350627f 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -1,6 +1,5 @@
 require 'cases/helper'
 require 'models/developer'
-require 'models/computer'
 require 'models/project'
 require 'models/company'
 require 'models/topic'
@@ -19,6 +18,11 @@ require 'models/invoice'
 require 'models/line_item'
 require 'models/column'
 require 'models/record'
+require 'models/admin'
+require 'models/admin/user'
+require 'models/ship'
+require 'models/treasure'
+require 'models/parrot'
 
 class BelongsToAssociationsTest < ActiveRecord::TestCase
   fixtures :accounts, :companies, :developers, :projects, :topics,
@@ -31,6 +35,10 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_equal companies(:first_firm).name, firm.name
   end
 
+  def test_missing_attribute_error_is_raised_when_no_foreign_key_attribute
+    assert_raises(ActiveModel::MissingAttributeError) { Client.select(:id).first.firm }
+  end
+
   def test_belongs_to_does_not_use_order_by
     ActiveRecord::SQLCounter.clear_log
     Client.find(3).firm
@@ -58,6 +66,56 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     end
   end
 
+  def test_optional_relation
+    original_value = ActiveRecord::Base.belongs_to_required_by_default
+    ActiveRecord::Base.belongs_to_required_by_default = true
+
+    model = Class.new(ActiveRecord::Base) do
+      self.table_name = "accounts"
+      def self.name; "Temp"; end
+      belongs_to :company, optional: true
+    end
+
+    account = model.new
+    assert account.valid?
+  ensure
+    ActiveRecord::Base.belongs_to_required_by_default = original_value
+  end
+
+  def test_not_optional_relation
+    original_value = ActiveRecord::Base.belongs_to_required_by_default
+    ActiveRecord::Base.belongs_to_required_by_default = true
+
+    model = Class.new(ActiveRecord::Base) do
+      self.table_name = "accounts"
+      def self.name; "Temp"; end
+      belongs_to :company, optional: false
+    end
+
+    account = model.new
+    assert_not account.valid?
+    assert_equal [{error: :blank}], account.errors.details[:company]
+  ensure
+    ActiveRecord::Base.belongs_to_required_by_default = original_value
+  end
+
+  def test_required_belongs_to_config
+    original_value = ActiveRecord::Base.belongs_to_required_by_default
+    ActiveRecord::Base.belongs_to_required_by_default = true
+
+    model = Class.new(ActiveRecord::Base) do
+      self.table_name = "accounts"
+      def self.name; "Temp"; end
+      belongs_to :company
+    end
+
+    account = model.new
+    assert_not account.valid?
+    assert_equal [{error: :blank}], account.errors.details[:company]
+  ensure
+    ActiveRecord::Base.belongs_to_required_by_default = original_value
+  end
+
   def test_default_scope_on_relations_is_not_cached
     counter = 0
 
@@ -74,9 +132,9 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
           where("id = :inc", :inc => counter)
         }
 
-        has_many :comments, :class => comments
+        has_many :comments, :anonymous_class => comments
       }
-      belongs_to :post, :class => posts, :inverse_of => false
+      belongs_to :post, :anonymous_class => posts, :inverse_of => false
     }
 
     assert_equal 0, counter
@@ -97,6 +155,30 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_raise(ActiveRecord::AssociationTypeMismatch) { Account.find(1).firm = Project.find(1) }
   end
 
+  def test_raises_type_mismatch_with_namespaced_class
+    assert_nil defined?(Region), "This test requires that there is no top-level Region class"
+
+    ActiveRecord::Base.connection.instance_eval do
+      create_table(:admin_regions) { |t| t.string :name }
+      add_column :admin_users, :region_id, :integer
+    end
+    Admin.const_set "RegionalUser", Class.new(Admin::User) { belongs_to(:region) }
+    Admin.const_set "Region", Class.new(ActiveRecord::Base)
+
+    e = assert_raise(ActiveRecord::AssociationTypeMismatch) {
+      Admin::RegionalUser.new(region: 'wrong value')
+    }
+    assert_match(/^Region\([^)]+\) expected, got String\([^)]+\)$/, e.message)
+  ensure
+    Admin.send :remove_const, "Region" if Admin.const_defined?("Region")
+    Admin.send :remove_const, "RegionalUser" if Admin.const_defined?("RegionalUser")
+
+    ActiveRecord::Base.connection.instance_eval do
+      remove_column :admin_users, :region_id if column_exists?(:admin_users, :region_id)
+      drop_table :admin_regions, if_exists: true
+    end
+  end
+
   def test_natural_assignment
     apple = Firm.create("name" => "Apple")
     citibank = Account.create("credit_limit" => 10)
@@ -122,14 +204,14 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     Firm.create("name" => "Apple")
     Client.create("name" => "Citibank", :firm_name => "Apple")
     citibank_result = Client.all.merge!(:where => {:name => "Citibank"}, :includes => :firm_with_primary_key).first
-    assert citibank_result.association_cache.key?(:firm_with_primary_key)
+    assert citibank_result.association(:firm_with_primary_key).loaded?
   end
 
   def test_eager_loading_with_primary_key_as_symbol
     Firm.create("name" => "Apple")
     Client.create("name" => "Citibank", :firm_name => "Apple")
     citibank_result = Client.all.merge!(:where => {:name => "Citibank"}, :includes => :firm_with_primary_key_symbols).first
-    assert citibank_result.association_cache.key?(:firm_with_primary_key_symbols)
+    assert citibank_result.association(:firm_with_primary_key_symbols).loaded?
   end
 
   def test_creating_the_belonging_object
@@ -213,7 +295,8 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     client = Client.find(3)
     client.firm = nil
     client.save
-    assert_nil client.firm(true)
+    client.association(:firm).reload
+    assert_nil client.firm
     assert_nil client.client_of
   end
 
@@ -221,7 +304,8 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     client = Client.create(:name => "Primary key client", :firm_name => companies(:first_firm).name)
     client.firm_with_primary_key = nil
     client.save
-    assert_nil client.firm_with_primary_key(true)
+    client.association(:firm_with_primary_key).reload
+    assert_nil client.firm_with_primary_key
     assert_nil client.client_of
   end
 
@@ -238,9 +322,13 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
   def test_polymorphic_association_class
     sponsor = Sponsor.new
     assert_nil sponsor.association(:sponsorable).send(:klass)
+    sponsor.association(:sponsorable).reload
+    assert_nil sponsor.sponsorable
 
     sponsor.sponsorable_type = '' # the column doesn't have to be declared NOT NULL
     assert_nil sponsor.association(:sponsorable).send(:klass)
+    sponsor.association(:sponsorable).reload
+    assert_nil sponsor.sponsorable
 
     sponsor.sponsorable = Member.new :name => "Bert"
     assert_equal Member, sponsor.association(:sponsorable).send(:klass)
@@ -261,6 +349,22 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_equal 1, Company.all.merge!(:includes => :firm_with_select ).find(2).firm_with_select.attributes.size
   end
 
+  def test_belongs_to_without_counter_cache_option
+    # Ship has a conventionally named `treasures_count` column, but the counter_cache
+    # option is not given on the association.
+    ship = Ship.create(name: 'Countless')
+
+    assert_no_difference lambda { ship.reload.treasures_count }, "treasures_count should not be changed unless counter_cache is given on the relation" do
+      treasure = Treasure.new(name: 'Gold', ship: ship)
+      treasure.save
+    end
+
+    assert_no_difference lambda { ship.reload.treasures_count }, "treasures_count should not be changed unless counter_cache is given on the relation" do
+      treasure = ship.treasures.first
+      treasure.destroy
+    end
+  end
+
   def test_belongs_to_counter
     debate = Topic.create("title" => "debate")
     assert_equal 0, debate.read_attribute("replies_count"), "No replies yet"
@@ -372,13 +476,33 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_queries(1) { line_item.touch }
   end
 
+  def test_belongs_to_with_touch_on_multiple_records
+    line_item = LineItem.create!(amount: 1)
+    line_item2 = LineItem.create!(amount: 2)
+    Invoice.create!(line_items: [line_item, line_item2])
+
+    assert_queries(1) do
+      LineItem.transaction do
+        line_item.touch
+        line_item2.touch
+      end
+    end
+
+    assert_queries(2) do
+      line_item.touch
+      line_item2.touch
+    end
+  end
+
   def test_belongs_to_with_touch_option_on_touch_without_updated_at_attributes
     assert_not LineItem.column_names.include?("updated_at")
 
     line_item = LineItem.create!
     invoice = Invoice.create!(line_items: [line_item])
     initial = invoice.updated_at
-    line_item.touch
+    travel(1.second) do
+      line_item.touch
+    end
 
     assert_not_equal initial, invoice.reload.updated_at
   end
@@ -457,7 +581,8 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert final_cut.persisted?
     assert firm.persisted?
     assert_equal firm, final_cut.firm
-    assert_equal firm, final_cut.firm(true)
+    final_cut.association(:firm).reload
+    assert_equal firm, final_cut.firm
   end
 
   def test_assignment_before_child_saved_with_primary_key
@@ -469,7 +594,8 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert final_cut.persisted?
     assert firm.persisted?
     assert_equal firm, final_cut.firm_with_primary_key
-    assert_equal firm, final_cut.firm_with_primary_key(true)
+    final_cut.association(:firm_with_primary_key).reload
+    assert_equal firm, final_cut.firm_with_primary_key
   end
 
   def test_new_record_with_foreign_key_but_no_object
@@ -964,6 +1090,12 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     Column.create! record: record
     assert_equal 1, Column.count
   end
+
+  def test_association_force_reload_with_only_true_is_deprecated
+    client = Client.find(3)
+
+    assert_deprecated { client.firm(true) }
+  end
 end
 
 class BelongsToWithForeignKeyTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/associations/eager_test.rb b/activerecord/test/cases/associations/eager_test.rb
index 371635d20a..bc1bff79d3 100644
--- a/activerecord/test/cases/associations/eager_test.rb
+++ b/activerecord/test/cases/associations/eager_test.rb
@@ -24,6 +24,8 @@ require 'models/membership'
 require 'models/club'
 require 'models/categorization'
 require 'models/sponsor'
+require 'models/mentor'
+require 'models/contract'
 
 class EagerAssociationTest < ActiveRecord::TestCase
   fixtures :posts, :comments, :authors, :essays, :author_addresses, :categories, :categories_posts,
@@ -77,9 +79,17 @@ class EagerAssociationTest < ActiveRecord::TestCase
 
   def test_has_many_through_with_order
     authors = Author.includes(:favorite_authors).to_a
+    assert authors.count > 0
     assert_no_queries { authors.map(&:favorite_authors) }
   end
 
+  def test_eager_loaded_has_one_association_with_references_does_not_run_additional_queries
+    Post.update_all(author_id: nil)
+    authors = Author.includes(:post).references(:post).to_a
+    assert authors.count > 0
+    assert_no_queries { authors.map(&:post) }
+  end
+
   def test_with_two_tables_in_from_without_getting_double_quoted
     posts = Post.select("posts.*").from("authors, posts").eager_load(:comments).where("posts.author_id = authors.id").order("posts.id").to_a
     assert_equal 2, posts.first.comments.size
@@ -100,53 +110,57 @@ class EagerAssociationTest < ActiveRecord::TestCase
   end
 
   def test_preloading_has_many_in_multiple_queries_with_more_ids_than_database_can_handle
-    Comment.connection.expects(:in_clause_length).at_least_once.returns(5)
-    posts = Post.all.merge!(:includes=>:comments).to_a
-    assert_equal 11, posts.size
+    assert_called(Comment.connection, :in_clause_length, returns: 5) do
+      posts = Post.all.merge!(:includes=>:comments).to_a
+      assert_equal 11, posts.size
+    end
   end
 
   def test_preloading_has_many_in_one_queries_when_database_has_no_limit_on_ids_it_can_handle
-    Comment.connection.expects(:in_clause_length).at_least_once.returns(nil)
-    posts = Post.all.merge!(:includes=>:comments).to_a
-    assert_equal 11, posts.size
+    assert_called(Comment.connection, :in_clause_length, returns: nil) do
+      posts = Post.all.merge!(:includes=>:comments).to_a
+      assert_equal 11, posts.size
+    end
   end
 
   def test_preloading_habtm_in_multiple_queries_with_more_ids_than_database_can_handle
-    Comment.connection.expects(:in_clause_length).at_least_once.returns(5)
-    posts = Post.all.merge!(:includes=>:categories).to_a
-    assert_equal 11, posts.size
+    assert_called(Comment.connection, :in_clause_length, times: 2, returns: 5) do
+      posts = Post.all.merge!(:includes=>:categories).to_a
+      assert_equal 11, posts.size
+    end
   end
 
   def test_preloading_habtm_in_one_queries_when_database_has_no_limit_on_ids_it_can_handle
-    Comment.connection.expects(:in_clause_length).at_least_once.returns(nil)
-    posts = Post.all.merge!(:includes=>:categories).to_a
-    assert_equal 11, posts.size
+    assert_called(Comment.connection, :in_clause_length, times: 2, returns: nil) do
+      posts = Post.all.merge!(:includes=>:categories).to_a
+      assert_equal 11, posts.size
+    end
   end
 
   def test_load_associated_records_in_one_query_when_adapter_has_no_limit
-    Comment.connection.expects(:in_clause_length).at_least_once.returns(nil)
-
-    post = posts(:welcome)
-    assert_queries(2) do
-      Post.includes(:comments).where(:id => post.id).to_a
+    assert_called(Comment.connection, :in_clause_length, returns: nil) do
+      post = posts(:welcome)
+      assert_queries(2) do
+        Post.includes(:comments).where(:id => post.id).to_a
+      end
     end
   end
 
   def test_load_associated_records_in_several_queries_when_many_ids_passed
-    Comment.connection.expects(:in_clause_length).at_least_once.returns(1)
-
-    post1, post2 = posts(:welcome), posts(:thinking)
-    assert_queries(3) do
-      Post.includes(:comments).where(:id => [post1.id, post2.id]).to_a
+    assert_called(Comment.connection, :in_clause_length, returns: 1) do
+      post1, post2 = posts(:welcome), posts(:thinking)
+      assert_queries(3) do
+        Post.includes(:comments).where(:id => [post1.id, post2.id]).to_a
+      end
     end
   end
 
   def test_load_associated_records_in_one_query_when_a_few_ids_passed
-    Comment.connection.expects(:in_clause_length).at_least_once.returns(3)
-
-    post = posts(:welcome)
-    assert_queries(2) do
-      Post.includes(:comments).where(:id => post.id).to_a
+    assert_called(Comment.connection, :in_clause_length, returns: 3) do
+      post = posts(:welcome)
+      assert_queries(2) do
+        Post.includes(:comments).where(:id => post.id).to_a
+      end
     end
   end
 
@@ -751,6 +765,23 @@ class EagerAssociationTest < ActiveRecord::TestCase
     end
   end
 
+  def test_eager_with_default_scope_as_class_method_using_find_method
+    david = developers(:david)
+    developer = EagerDeveloperWithClassMethodDefaultScope.find(david.id)
+    projects = Project.order(:id).to_a
+    assert_no_queries do
+      assert_equal(projects, developer.projects)
+    end
+  end
+
+  def test_eager_with_default_scope_as_class_method_using_find_by_method
+    developer = EagerDeveloperWithClassMethodDefaultScope.find_by(name: 'David')
+    projects = Project.order(:id).to_a
+    assert_no_queries do
+      assert_equal(projects, developer.projects)
+    end
+  end
+
   def test_eager_with_default_scope_as_lambda
     developer = EagerDeveloperWithLambdaDefaultScope.where(:name => 'David').first
     projects = Project.order(:id).to_a
@@ -1142,7 +1173,7 @@ class EagerAssociationTest < ActiveRecord::TestCase
     assert_no_queries { assert client.accounts.empty? }
   end
 
-  def test_preloading_has_many_through_with_uniq
+  def test_preloading_has_many_through_with_distinct
     mary = Author.includes(:unique_categorized_posts).where(:id => authors(:mary).id).first
     assert_equal 1, mary.unique_categorized_posts.length
     assert_equal 1, mary.unique_categorized_post_ids.length
@@ -1189,6 +1220,16 @@ class EagerAssociationTest < ActiveRecord::TestCase
     assert_no_queries { assert_equal 2, posts[1].categories[0].categorizations.length }
   end
 
+  def test_eager_load_multiple_associations_with_references
+    mentor = Mentor.create!(name: "Barış Can DAYLIK")
+    developer = Developer.create!(name: "Mehmet Emin İNAÇ", mentor: mentor)
+    Contract.create!(developer: developer)
+    project = Project.create!(name: "VNGRS", mentor: mentor)
+    project.developers << developer
+    projects = Project.references(:mentors).includes(mentor: { developers: :contracts }, developers: :contracts)
+    assert_equal projects.last.mentor.developers.first.contracts, projects.last.developers.last.contracts
+  end
+
   test "scoping with a circular preload" do
     assert_equal Comment.find(1), Comment.preload(:post => :comments).scoping { Comment.find(1) }
   end
@@ -1300,6 +1341,14 @@ class EagerAssociationTest < ActiveRecord::TestCase
     assert_match message, error.message
   end
 
+  test "preload with invalid argument" do
+    exception = assert_raises(ArgumentError) do
+      Author.preload(10).to_a
+    end
+    assert_equal('10 was not recognized for preload', exception.message)
+  end
+
+
   test "preloading readonly association" do
     # has-one
     firm = Firm.where(id: "1").preload(:readonly_account).first!
diff --git a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
index aea9207bfe..e9f679e6de 100644
--- a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
@@ -3,6 +3,7 @@ require 'models/developer'
 require 'models/computer'
 require 'models/project'
 require 'models/company'
+require 'models/course'
 require 'models/customer'
 require 'models/order'
 require 'models/categorization'
@@ -14,6 +15,7 @@ require 'models/tagging'
 require 'models/parrot'
 require 'models/person'
 require 'models/pirate'
+require 'models/professor'
 require 'models/treasure'
 require 'models/price_estimate'
 require 'models/club'
@@ -83,6 +85,25 @@ class DeveloperWithSymbolClassName < Developer
   has_and_belongs_to_many :projects, class_name: :ProjectWithSymbolsForKeys
 end
 
+class DeveloperWithExtendOption < Developer
+  module NamedExtension
+    def category
+      'sns'
+    end
+  end
+
+  has_and_belongs_to_many :projects, extend: NamedExtension
+end
+
+class ProjectUnscopingDavidDefaultScope < ActiveRecord::Base
+  self.table_name = 'projects'
+  has_and_belongs_to_many :developers, -> { unscope(where: 'name') },
+    class_name: "LazyBlockDeveloperCalledDavid",
+    join_table: "developers_projects",
+    foreign_key: "project_id",
+    association_foreign_key: "developer_id"
+end
+
 class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
   fixtures :accounts, :companies, :categories, :posts, :categories_posts, :developers, :projects, :developers_projects,
            :parrots, :pirates, :parrots_pirates, :treasures, :price_estimates, :tags, :taggings, :computers
@@ -147,8 +168,8 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     jamis.projects << action_controller
 
     assert_equal 2, jamis.projects.size
-    assert_equal 2, jamis.projects(true).size
-    assert_equal 2, action_controller.developers(true).size
+    assert_equal 2, jamis.projects.reload.size
+    assert_equal 2, action_controller.developers.reload.size
   end
 
   def test_adding_type_mismatch
@@ -166,9 +187,9 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
 
     action_controller.developers << jamis
 
-    assert_equal 2, jamis.projects(true).size
+    assert_equal 2, jamis.projects.reload.size
     assert_equal 2, action_controller.developers.size
-    assert_equal 2, action_controller.developers(true).size
+    assert_equal 2, action_controller.developers.reload.size
   end
 
   def test_adding_from_the_project_fixed_timestamp
@@ -182,9 +203,9 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     action_controller.developers << jamis
 
     assert_equal updated_at, jamis.updated_at
-    assert_equal 2, jamis.projects(true).size
+    assert_equal 2, jamis.projects.reload.size
     assert_equal 2, action_controller.developers.size
-    assert_equal 2, action_controller.developers(true).size
+    assert_equal 2, action_controller.developers.reload.size
   end
 
   def test_adding_multiple
@@ -193,7 +214,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     aredridel.projects.reload
     aredridel.projects.push(Project.find(1), Project.find(2))
     assert_equal 2, aredridel.projects.size
-    assert_equal 2, aredridel.projects(true).size
+    assert_equal 2, aredridel.projects.reload.size
   end
 
   def test_adding_a_collection
@@ -202,7 +223,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     aredridel.projects.reload
     aredridel.projects.concat([Project.find(1), Project.find(2)])
     assert_equal 2, aredridel.projects.size
-    assert_equal 2, aredridel.projects(true).size
+    assert_equal 2, aredridel.projects.reload.size
   end
 
   def test_habtm_adding_before_save
@@ -217,7 +238,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_equal no_of_devels+1, Developer.count
     assert_equal no_of_projects+1, Project.count
     assert_equal 2, aredridel.projects.size
-    assert_equal 2, aredridel.projects(true).size
+    assert_equal 2, aredridel.projects.reload.size
   end
 
   def test_habtm_saving_multiple_relationships
@@ -234,7 +255,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_equal developers, new_project.developers
   end
 
-  def test_habtm_unique_order_preserved
+  def test_habtm_distinct_order_preserved
     assert_equal developers(:poor_jamis, :jamis, :david), projects(:active_record).non_unique_developers
     assert_equal developers(:poor_jamis, :jamis, :david), projects(:active_record).developers
   end
@@ -339,7 +360,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_equal  'Yet Another Testing Title', another_post.title
   end
 
-  def test_uniq_after_the_fact
+  def test_distinct_after_the_fact
     dev = developers(:jamis)
     dev.projects << projects(:active_record)
     dev.projects << projects(:active_record)
@@ -348,13 +369,13 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_equal 1, dev.projects.distinct.size
   end
 
-  def test_uniq_before_the_fact
+  def test_distinct_before_the_fact
     projects(:active_record).developers << developers(:jamis)
     projects(:active_record).developers << developers(:david)
     assert_equal 3, projects(:active_record, :reload).developers.size
   end
 
-  def test_uniq_option_prevents_duplicate_push
+  def test_distinct_option_prevents_duplicate_push
     project = projects(:active_record)
     project.developers << developers(:jamis)
     project.developers << developers(:david)
@@ -365,7 +386,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_equal 3, project.developers.size
   end
 
-  def test_uniq_when_association_already_loaded
+  def test_distinct_when_association_already_loaded
     project = projects(:active_record)
     project.developers << [ developers(:jamis), developers(:david), developers(:jamis), developers(:david) ]
     assert_equal 3, Project.includes(:developers).find(project.id).developers.size
@@ -381,8 +402,8 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     david.projects.delete(active_record)
 
     assert_equal 1, david.projects.size
-    assert_equal 1, david.projects(true).size
-    assert_equal 2, active_record.developers(true).size
+    assert_equal 1, david.projects.reload.size
+    assert_equal 2, active_record.developers.reload.size
   end
 
   def test_deleting_array
@@ -390,7 +411,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     david.projects.reload
     david.projects.delete(Project.all.to_a)
     assert_equal 0, david.projects.size
-    assert_equal 0, david.projects(true).size
+    assert_equal 0, david.projects.reload.size
   end
 
   def test_deleting_all
@@ -398,7 +419,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     david.projects.reload
     david.projects.clear
     assert_equal 0, david.projects.size
-    assert_equal 0, david.projects(true).size
+    assert_equal 0, david.projects.reload.size
   end
 
   def test_removing_associations_on_destroy
@@ -424,7 +445,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert join_records.empty?
 
     assert_equal 1, david.reload.projects.size
-    assert_equal 1, david.projects(true).size
+    assert_equal 1, david.projects.reload.size
   end
 
   def test_destroying_many
@@ -440,7 +461,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert join_records.empty?
 
     assert_equal 0, david.reload.projects.size
-    assert_equal 0, david.projects(true).size
+    assert_equal 0, david.projects.reload.size
   end
 
   def test_destroy_all
@@ -456,7 +477,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert join_records.empty?
 
     assert david.projects.empty?
-    assert david.projects(true).empty?
+    assert david.projects.reload.empty?
   end
 
   def test_destroy_associations_destroys_multiple_associations
@@ -472,11 +493,11 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
 
     join_records = Parrot.connection.select_all("SELECT * FROM parrots_pirates WHERE parrot_id = #{george.id}")
     assert join_records.empty?
-    assert george.pirates(true).empty?
+    assert george.pirates.reload.empty?
 
     join_records = Parrot.connection.select_all("SELECT * FROM parrots_treasures WHERE parrot_id = #{george.id}")
     assert join_records.empty?
-    assert george.treasures(true).empty?
+    assert george.treasures.reload.empty?
   end
 
   def test_associations_with_conditions
@@ -577,6 +598,11 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_equal developers(:poor_jamis), projects(:active_record).developers.where("salary < 10000").first
   end
 
+  def test_association_with_extend_option
+    eponine = DeveloperWithExtendOption.create(name: 'Eponine')
+    assert_equal 'sns', eponine.projects.category
+  end
+
   def test_replace_with_less
     david = developers(:david)
     david.projects = [projects(:action_controller)]
@@ -639,7 +665,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
   end
 
   def test_habtm_respects_select
-    categories(:technology).select_testing_posts(true).each do |o|
+    categories(:technology).select_testing_posts.reload.each do |o|
       assert_respond_to o, :correctness_marker
     end
     assert_respond_to categories(:technology).select_testing_posts.first, :correctness_marker
@@ -711,7 +737,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
 
   def test_get_ids_for_loaded_associations
     developer = developers(:david)
-    developer.projects(true)
+    developer.projects.reload
     assert_queries(0) do
       developer.project_ids
       developer.project_ids
@@ -779,9 +805,10 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
   end
 
   def test_association_proxy_transaction_method_starts_transaction_in_association_class
-    Post.expects(:transaction)
-    Category.first.posts.transaction do
-      # nothing
+    assert_called(Post, :transaction) do
+      Category.first.posts.transaction do
+        # nothing
+      end
     end
   end
 
@@ -902,4 +929,51 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
       DeveloperWithSymbolClassName.new
     end
   end
+
+  def test_association_force_reload_with_only_true_is_deprecated
+    developer = Developer.find(1)
+
+    assert_deprecated { developer.projects(true) }
+  end
+
+  def test_alternate_database
+    professor = Professor.create(name: "Plum")
+    course = Course.create(name: "Forensics")
+    assert_equal 0, professor.courses.count
+    assert_nothing_raised do
+      professor.courses << course
+    end
+    assert_equal 1, professor.courses.count
+  end
+
+  def test_habtm_scope_can_unscope
+    project = ProjectUnscopingDavidDefaultScope.new
+    project.save!
+
+    developer = LazyBlockDeveloperCalledDavid.new(name: "Not David")
+    developer.save!
+    project.developers << developer
+
+    projects = ProjectUnscopingDavidDefaultScope.includes(:developers).where(id: project.id)
+    assert_equal 1, projects.first.developers.size
+  end
+
+  def test_preloaded_associations_size
+    assert_equal Project.first.salaried_developers.size,
+      Project.preload(:salaried_developers).first.salaried_developers.size
+
+    assert_equal Project.includes(:salaried_developers).references(:salaried_developers).first.salaried_developers.size,
+      Project.preload(:salaried_developers).first.salaried_developers.size
+
+    # Nested HATBM
+    first_project = Developer.first.projects.first
+    preloaded_first_project =
+      Developer.preload(projects: :salaried_developers).
+        first.
+        projects.
+        detect { |p| p.id == first_project.id }
+
+    assert preloaded_first_project.salaried_developers.loaded?, true
+    assert_equal first_project.salaried_developers.size, preloaded_first_project.salaried_developers.size
+  end
 end
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 21a45042fa..eb94870a35 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -30,9 +30,14 @@ require 'models/college'
 require 'models/student'
 require 'models/pirate'
 require 'models/ship'
+require 'models/ship_part'
+require 'models/treasure'
+require 'models/parrot'
 require 'models/tyre'
 require 'models/subscriber'
 require 'models/subscription'
+require 'models/zine'
+require 'models/interest'
 
 class HasManyAssociationsTestForReorderWithJoinDependency < ActiveRecord::TestCase
   fixtures :authors, :posts, :comments
@@ -97,7 +102,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
   fixtures :accounts, :categories, :companies, :developers, :projects,
            :developers_projects, :topics, :authors, :comments,
            :posts, :readers, :taggings, :cars, :jobs, :tags,
-           :categorizations
+           :categorizations, :zines, :interests
 
   def setup
     Client.destroyed_client_ids.clear
@@ -116,9 +121,9 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
 
       developer_project = Class.new(ActiveRecord::Base) {
         self.table_name = 'developers_projects'
-        belongs_to :developer, :class => dev
+        belongs_to :developer, :anonymous_class => dev
       }
-      has_many :developer_projects, :class => developer_project, :foreign_key => 'developer_id'
+      has_many :developer_projects, :anonymous_class => developer_project, :foreign_key => 'developer_id'
     }
     dev = developer.first
     named = Developer.find(dev.id)
@@ -137,13 +142,13 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
       comments = Class.new(ActiveRecord::Base) {
         self.table_name = 'comments'
         self.inheritance_column = 'not_there'
-        belongs_to :post, :class => post
+        belongs_to :post, :anonymous_class => post
         default_scope -> {
           counter += 1
           where("id = :inc", :inc => counter)
         }
       }
-      has_many :comments, :class => comments, :foreign_key => 'post_id'
+      has_many :comments, :anonymous_class => comments, :foreign_key => 'post_id'
     }
     assert_equal 0, counter
     post = posts.first
@@ -160,6 +165,32 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal college.students, Student.where(active: true, college_id: college.id)
   end
 
+  def test_add_record_to_collection_should_change_its_updated_at
+    ship = Ship.create(name: 'dauntless')
+    part = ShipPart.create(name: 'cockpit')
+    updated_at = part.updated_at
+
+    travel(1.second) do
+      ship.parts << part
+    end
+
+    assert_equal part.ship, ship
+    assert_not_equal part.updated_at, updated_at
+  end
+
+  def test_clear_collection_should_not_change_updated_at
+    # GH#17161: .clear calls delete_all (and returns the association),
+    # which is intended to not touch associated objects's updated_at field
+    ship = Ship.create(name: 'dauntless')
+    part = ShipPart.create(name: 'cockpit', ship_id: ship.id)
+
+    ship.parts.clear
+    part.reload
+
+    assert_equal nil, part.ship
+    assert !part.updated_at_changed?
+  end
+
   def test_create_from_association_should_respect_default_scope
     car = Car.create(:name => 'honda')
     assert_equal 'honda', car.name
@@ -316,16 +347,16 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
   # would be convenient), because this would cause that scope to be applied to any callbacks etc.
   def test_build_and_create_should_not_happen_within_scope
     car = cars(:honda)
-    scoped_count = car.foo_bulbs.where_values.count
+    scope = car.foo_bulbs.where_values_hash
 
     bulb = car.foo_bulbs.build
-    assert_not_equal scoped_count, bulb.scope_after_initialize.where_values.count
+    assert_not_equal scope, bulb.scope_after_initialize.where_values_hash
 
     bulb = car.foo_bulbs.create
-    assert_not_equal scoped_count, bulb.scope_after_initialize.where_values.count
+    assert_not_equal scope, bulb.scope_after_initialize.where_values_hash
 
     bulb = car.foo_bulbs.create!
-    assert_not_equal scoped_count, bulb.scope_after_initialize.where_values.count
+    assert_not_equal scope, bulb.scope_after_initialize.where_values_hash
   end
 
   def test_no_sql_should_be_fired_if_association_already_loaded
@@ -435,6 +466,45 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal companies(:another_first_firm_client), companies(:first_firm).clients_sorted_desc.find_by_type('Client')
   end
 
+  def test_taking
+    posts(:other_by_bob).destroy
+    assert_equal posts(:misc_by_bob), authors(:bob).posts.take
+    assert_equal posts(:misc_by_bob), authors(:bob).posts.take!
+    authors(:bob).posts.to_a
+    assert_equal posts(:misc_by_bob), authors(:bob).posts.take
+    assert_equal posts(:misc_by_bob), authors(:bob).posts.take!
+  end
+
+  def test_taking_not_found
+    authors(:bob).posts.delete_all
+    assert_raise(ActiveRecord::RecordNotFound) { authors(:bob).posts.take! }
+    authors(:bob).posts.to_a
+    assert_raise(ActiveRecord::RecordNotFound) { authors(:bob).posts.take! }
+  end
+
+  def test_taking_with_a_number
+    # taking from unloaded Relation
+    bob = Author.find(authors(:bob).id)
+    assert_equal [posts(:misc_by_bob)], bob.posts.take(1)
+    bob = Author.find(authors(:bob).id)
+    assert_equal [posts(:misc_by_bob), posts(:other_by_bob)], bob.posts.take(2)
+
+    # taking from loaded Relation
+    bob.posts.to_a
+    assert_equal [posts(:misc_by_bob)], authors(:bob).posts.take(1)
+    assert_equal [posts(:misc_by_bob), posts(:other_by_bob)], authors(:bob).posts.take(2)
+  end
+
+  def test_taking_with_inverse_of
+    interests(:woodsmanship).destroy
+    interests(:survival).destroy
+
+    zine = zines(:going_out)
+    interest = zine.interests.take
+    assert_equal interests(:hunting), interest
+    assert_same zine, interest.zine
+  end
+
   def test_cant_save_has_many_readonly_association
     authors(:david).readonly_comments.each { |c| assert_raise(ActiveRecord::ReadOnlyRecord) { c.save! } }
     authors(:david).readonly_comments.each { |c| assert c.readonly? }
@@ -466,9 +536,21 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
 
   def test_update_all_on_association_accessed_before_save
     firm = Firm.new(name: 'Firm')
+    clients_proxy_id = firm.clients.object_id
     firm.clients << Client.first
     firm.save!
     assert_equal firm.clients.count, firm.clients.update_all(description: 'Great!')
+    assert_not_equal clients_proxy_id, firm.clients.object_id
+  end
+
+  def test_update_all_on_association_accessed_before_save_with_explicit_foreign_key
+    # We can use the same cached proxy object because the id is available for the scope
+    firm = Firm.new(name: 'Firm', id: 100)
+    clients_proxy_id = firm.clients.object_id
+    firm.clients << Client.first
+    firm.save!
+    assert_equal firm.clients.count, firm.clients.update_all(description: 'Great!')
+    assert_equal clients_proxy_id, firm.clients.object_id
   end
 
   def test_belongs_to_sanity
@@ -626,7 +708,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     natural = Client.new("name" => "Natural Company")
     companies(:first_firm).clients_of_firm << natural
     assert_equal 3, companies(:first_firm).clients_of_firm.size # checking via the collection
-    assert_equal 3, companies(:first_firm).clients_of_firm(true).size # checking using the db
+    assert_equal 3, companies(:first_firm).clients_of_firm.reload.size # checking using the db
     assert_equal natural, companies(:first_firm).clients_of_firm.last
   end
 
@@ -681,7 +763,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     force_signal37_to_load_all_clients_of_firm
     companies(:first_firm).clients_of_firm.concat([Client.new("name" => "Natural Company"), Client.new("name" => "Apple")])
     assert_equal 4, companies(:first_firm).clients_of_firm.size
-    assert_equal 4, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 4, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_transactions_when_adding_to_persisted
@@ -693,7 +775,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     rescue Client::RaisedOnSave
     end
 
-    assert !companies(:first_firm).clients_of_firm(true).include?(good)
+    assert !companies(:first_firm).clients_of_firm.reload.include?(good)
   end
 
   def test_transactions_when_adding_to_new_record
@@ -825,12 +907,12 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     new_client = companies(:first_firm).clients_of_firm.create("name" => "Another Client")
     assert new_client.persisted?
     assert_equal new_client, companies(:first_firm).clients_of_firm.last
-    assert_equal new_client, companies(:first_firm).clients_of_firm(true).last
+    assert_equal new_client, companies(:first_firm).clients_of_firm.reload.last
   end
 
   def test_create_many
     companies(:first_firm).clients_of_firm.create([{"name" => "Another Client"}, {"name" => "Another Client II"}])
-    assert_equal 4, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 4, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_create_followed_by_save_does_not_load_target
@@ -843,7 +925,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     force_signal37_to_load_all_clients_of_firm
     companies(:first_firm).clients_of_firm.delete(companies(:first_firm).clients_of_firm.first)
     assert_equal 1, companies(:first_firm).clients_of_firm.size
-    assert_equal 1, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 1, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_deleting_before_save
@@ -854,6 +936,25 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal 0, new_firm.clients_of_firm.size
   end
 
+  def test_has_many_without_counter_cache_option
+    # Ship has a conventionally named `treasures_count` column, but the counter_cache
+    # option is not given on the association.
+    ship = Ship.create(name: 'Countless', treasures_count: 10)
+
+    assert_not Ship.reflect_on_association(:treasures).has_cached_counter?
+
+    # Count should come from sql count() of treasures rather than treasures_count attribute
+    assert_equal ship.treasures.size, 0
+
+    assert_no_difference lambda { ship.reload.treasures_count }, "treasures_count should not be changed" do
+      ship.treasures.create(name: 'Gold')
+    end
+
+    assert_no_difference lambda { ship.reload.treasures_count }, "treasures_count should not be changed" do
+      ship.treasures.destroy_all
+    end
+  end
+
   def test_deleting_updates_counter_cache
     topic = Topic.order("id ASC").first
     assert_equal topic.replies.to_a.size, topic.replies_count
@@ -980,7 +1081,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal 3, companies(:first_firm).clients_of_firm.size
     companies(:first_firm).clients_of_firm.delete([companies(:first_firm).clients_of_firm[0], companies(:first_firm).clients_of_firm[1], companies(:first_firm).clients_of_firm[2]])
     assert_equal 0, companies(:first_firm).clients_of_firm.size
-    assert_equal 0, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 0, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_delete_all
@@ -1001,7 +1102,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     companies(:first_firm).clients_of_firm.reset
     companies(:first_firm).clients_of_firm.delete_all
     assert_equal 0, companies(:first_firm).clients_of_firm.size
-    assert_equal 0, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 0, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_transaction_when_deleting_persisted
@@ -1015,7 +1116,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     rescue Client::RaisedOnDestroy
     end
 
-    assert_equal [good, bad], companies(:first_firm).clients_of_firm(true)
+    assert_equal [good, bad], companies(:first_firm).clients_of_firm.reload
   end
 
   def test_transaction_when_deleting_new_record
@@ -1035,7 +1136,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     firm.clients_of_firm.clear
 
     assert_equal 0, firm.clients_of_firm.size
-    assert_equal 0, firm.clients_of_firm(true).size
+    assert_equal 0, firm.clients_of_firm.reload.size
     assert_equal [], Client.destroyed_client_ids[firm.id]
 
     # Should not be destroyed since the association is not dependent.
@@ -1071,7 +1172,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     firm.dependent_clients_of_firm.clear
 
     assert_equal 0, firm.dependent_clients_of_firm.size
-    assert_equal 0, firm.dependent_clients_of_firm(true).size
+    assert_equal 0, firm.dependent_clients_of_firm.reload.size
     assert_equal [], Client.destroyed_client_ids[firm.id]
 
     # Should be destroyed since the association is dependent.
@@ -1104,7 +1205,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     firm.exclusively_dependent_clients_of_firm.clear
 
     assert_equal 0, firm.exclusively_dependent_clients_of_firm.size
-    assert_equal 0, firm.exclusively_dependent_clients_of_firm(true).size
+    assert_equal 0, firm.exclusively_dependent_clients_of_firm.reload.size
     # no destroy-filters should have been called
     assert_equal [], Client.destroyed_client_ids[firm.id]
 
@@ -1153,7 +1254,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     # break the vanilla firm_id foreign key
     assert_equal 3, firm.clients.count
     firm.clients.first.update_columns(firm_id: nil)
-    assert_equal 2, firm.clients(true).count
+    assert_equal 2, firm.clients.reload.count
     assert_equal 2, firm.clients_using_primary_key_with_delete_all.count
     old_record = firm.clients_using_primary_key_with_delete_all.first
     firm = Firm.first
@@ -1179,7 +1280,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     firm.clients_of_firm.clear
 
     assert_equal 0, firm.clients_of_firm.size
-    assert_equal 0, firm.clients_of_firm(true).size
+    assert_equal 0, firm.clients_of_firm.reload.size
   end
 
   def test_deleting_a_item_which_is_not_in_the_collection
@@ -1187,7 +1288,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     summit = Client.find_by_name('Summit')
     companies(:first_firm).clients_of_firm.delete(summit)
     assert_equal 2, companies(:first_firm).clients_of_firm.size
-    assert_equal 2, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 2, companies(:first_firm).clients_of_firm.reload.size
     assert_equal 2, summit.client_of
   end
 
@@ -1225,7 +1326,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     end
 
     assert_equal 1, companies(:first_firm).reload.clients_of_firm.size
-    assert_equal 1, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 1, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_destroying_by_fixnum_id
@@ -1236,7 +1337,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     end
 
     assert_equal 1, companies(:first_firm).reload.clients_of_firm.size
-    assert_equal 1, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 1, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_destroying_by_string_id
@@ -1247,7 +1348,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     end
 
     assert_equal 1, companies(:first_firm).reload.clients_of_firm.size
-    assert_equal 1, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 1, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_destroying_a_collection
@@ -1260,7 +1361,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     end
 
     assert_equal 1, companies(:first_firm).reload.clients_of_firm.size
-    assert_equal 1, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 1, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_destroy_all
@@ -1271,7 +1372,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal clients.sort_by(&:id), destroyed.sort_by(&:id)
     assert destroyed.all?(&:frozen?), "destroyed clients should be frozen"
     assert companies(:first_firm).clients_of_firm.empty?, "37signals has no clients after destroy all"
-    assert companies(:first_firm).clients_of_firm(true).empty?, "37signals has no clients after destroy all and refresh"
+    assert companies(:first_firm).clients_of_firm.reload.empty?, "37signals has no clients after destroy all and refresh"
   end
 
   def test_dependence
@@ -1307,7 +1408,6 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_nothing_raised { topic.destroy }
   end
 
-  uses_transaction :test_dependence_with_transaction_support_on_failure
   def test_dependence_with_transaction_support_on_failure
     firm = companies(:first_firm)
     clients = firm.clients
@@ -1349,6 +1449,26 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert firm.companies.exists?(:name => 'child')
   end
 
+  def test_restrict_with_error_is_deprecated_using_key_many
+    I18n.backend = I18n::Backend::Simple.new
+    I18n.backend.store_translations :en, activerecord: { errors: { messages: { restrict_dependent_destroy: { many: 'message for deprecated key' } } } }
+
+    firm = RestrictedWithErrorFirm.create!(name: 'restrict')
+    firm.companies.create(name: 'child')
+
+    assert !firm.companies.empty?
+
+    assert_deprecated { firm.destroy }
+
+    assert !firm.errors.empty?
+
+    assert_equal 'message for deprecated key', firm.errors[:base].first
+    assert RestrictedWithErrorFirm.exists?(name: 'restrict')
+    assert firm.companies.exists?(name: 'child')
+  ensure
+    I18n.backend.reload!
+  end
+
   def test_restrict_with_error
     firm = RestrictedWithErrorFirm.create!(:name => 'restrict')
     firm.companies.create(:name => 'child')
@@ -1364,6 +1484,25 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert firm.companies.exists?(:name => 'child')
   end
 
+  def test_restrict_with_error_with_locale
+    I18n.backend = I18n::Backend::Simple.new
+    I18n.backend.store_translations 'en', activerecord: {attributes: {restricted_with_error_firm: {companies: 'client companies'}}}
+    firm = RestrictedWithErrorFirm.create!(name: 'restrict')
+    firm.companies.create(name: 'child')
+
+    assert !firm.companies.empty?
+
+    firm.destroy
+
+    assert !firm.errors.empty?
+
+    assert_equal "Cannot delete record because dependent client companies exist", firm.errors[:base].first
+    assert RestrictedWithErrorFirm.exists?(name: 'restrict')
+    assert firm.companies.exists?(name: 'child')
+  ensure
+    I18n.backend.reload!
+  end
+
   def test_included_in_collection
     assert_equal true, companies(:first_firm).clients.include?(Client.find(2))
   end
@@ -1426,6 +1565,8 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_queries(0, ignore_none: true) do
       firm.clients = []
     end
+
+    assert_equal [], firm.send('clients=', [])
   end
 
   def test_transactions_when_replacing_on_persisted
@@ -1439,7 +1580,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     rescue Client::RaisedOnSave
     end
 
-    assert_equal [good], companies(:first_firm).clients_of_firm(true)
+    assert_equal [good], companies(:first_firm).clients_of_firm.reload
   end
 
   def test_transactions_when_replacing_on_new_record
@@ -1455,7 +1596,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
 
   def test_get_ids_for_loaded_associations
     company = companies(:first_firm)
-    company.clients(true)
+    company.clients.reload
     assert_queries(0) do
       company.client_ids
       company.client_ids
@@ -1509,7 +1650,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     firm.client_ids = [companies(:first_client).id, nil, companies(:second_client).id, '']
     firm.save!
 
-    assert_equal 2, firm.clients(true).size
+    assert_equal 2, firm.clients.reload.size
     assert_equal true, firm.clients.include?(companies(:second_client))
   end
 
@@ -1679,6 +1820,82 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal 3, firm.clients.size
   end
 
+  def test_calling_none_should_count_instead_of_loading_association
+    firm = companies(:first_firm)
+    assert_queries(1) do
+      firm.clients.none?  # use count query
+    end
+    assert !firm.clients.loaded?
+  end
+
+  def test_calling_none_on_loaded_association_should_not_use_query
+    firm = companies(:first_firm)
+    firm.clients.collect  # force load
+    assert_no_queries { assert ! firm.clients.none? }
+  end
+
+  def test_calling_none_should_defer_to_collection_if_using_a_block
+    firm = companies(:first_firm)
+    assert_queries(1) do
+      firm.clients.expects(:size).never
+      firm.clients.none? { true }
+    end
+    assert firm.clients.loaded?
+  end
+
+  def test_calling_none_should_return_true_if_none
+    firm = companies(:another_firm)
+    assert firm.clients_like_ms.none?
+    assert_equal 0, firm.clients_like_ms.size
+  end
+
+  def test_calling_none_should_return_false_if_any
+    firm = companies(:first_firm)
+    assert !firm.limited_clients.none?
+    assert_equal 1, firm.limited_clients.size
+  end
+
+  def test_calling_one_should_count_instead_of_loading_association
+    firm = companies(:first_firm)
+    assert_queries(1) do
+      firm.clients.one?  # use count query
+    end
+    assert !firm.clients.loaded?
+  end
+
+  def test_calling_one_on_loaded_association_should_not_use_query
+    firm = companies(:first_firm)
+    firm.clients.collect  # force load
+    assert_no_queries { assert ! firm.clients.one? }
+  end
+
+  def test_calling_one_should_defer_to_collection_if_using_a_block
+    firm = companies(:first_firm)
+    assert_queries(1) do
+      firm.clients.expects(:size).never
+      firm.clients.one? { true }
+    end
+    assert firm.clients.loaded?
+  end
+
+  def test_calling_one_should_return_false_if_zero
+    firm = companies(:another_firm)
+    assert ! firm.clients_like_ms.one?
+    assert_equal 0, firm.clients_like_ms.size
+  end
+
+  def test_calling_one_should_return_true_if_one
+    firm = companies(:first_firm)
+    assert firm.limited_clients.one?
+    assert_equal 1, firm.limited_clients.size
+  end
+
+  def test_calling_one_should_return_false_if_more_than_one
+    firm = companies(:first_firm)
+    assert ! firm.clients.one?
+    assert_equal 3, firm.clients.size
+  end
+
   def test_joins_with_namespaced_model_should_use_correct_type
     old = ActiveRecord::Base.store_full_sti_class
     ActiveRecord::Base.store_full_sti_class = true
@@ -1964,6 +2181,26 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal [bulb1, bulb2], car.all_bulbs.sort_by(&:id)
   end
 
+  test "can unscope and where the default scope of the associated model" do
+    Car.has_many :other_bulbs, -> { unscope(where: [:name]).where(name: 'other') }, class_name: "Bulb"
+    car = Car.create!
+    bulb1 = Bulb.create! name: "defaulty", car: car
+    bulb2 = Bulb.create! name: "other",    car: car
+
+    assert_equal [bulb1], car.bulbs
+    assert_equal [bulb2], car.other_bulbs
+  end
+
+  test "can rewhere the default scope of the associated model" do
+    Car.has_many :old_bulbs, -> { rewhere(name: 'old') }, class_name: "Bulb"
+    car = Car.create!
+    bulb1 = Bulb.create! name: "defaulty", car: car
+    bulb2 = Bulb.create! name: "old",      car: car
+
+    assert_equal [bulb1], car.bulbs
+    assert_equal [bulb2], car.old_bulbs
+  end
+
   test 'unscopes the default scope of associated model when used with include' do
     car = Car.create!
     bulb = Bulb.create! name: "other", car: car
@@ -1976,11 +2213,12 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     car = Car.create!
     original_child = FailedBulb.create!(car: car)
 
-    assert_raise(ActiveRecord::RecordNotDestroyed) do
+    error = assert_raise(ActiveRecord::RecordNotDestroyed) do
       car.failed_bulbs = [FailedBulb.create!]
     end
 
     assert_equal [original_child], car.reload.failed_bulbs
+    assert_equal "Failed to destroy the record", error.message
   end
 
   test 'updates counter cache when default scope is given' do
@@ -2096,4 +2334,48 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
 
     assert_equal [first_bulb, second_bulb], car.bulbs
   end
+
+  def test_association_force_reload_with_only_true_is_deprecated
+    company = Company.find(1)
+
+    assert_deprecated { company.clients_of_firm(true) }
+  end
+
+  class AuthorWithErrorDestroyingAssociation < ActiveRecord::Base
+    self.table_name = "authors"
+    has_many :posts_with_error_destroying,
+      class_name: "PostWithErrorDestroying",
+      foreign_key: :author_id,
+      dependent: :destroy
+  end
+
+  class PostWithErrorDestroying < ActiveRecord::Base
+    self.table_name = "posts"
+    self.inheritance_column = nil
+    before_destroy -> { throw :abort }
+  end
+
+  def test_destroy_does_not_raise_when_association_errors_on_destroy
+    assert_no_difference "AuthorWithErrorDestroyingAssociation.count" do
+      author = AuthorWithErrorDestroyingAssociation.first
+
+      assert_not author.destroy
+    end
+  end
+
+  def test_destroy_with_bang_bubbles_errors_from_associations
+    error = assert_raises ActiveRecord::RecordNotDestroyed do
+      AuthorWithErrorDestroyingAssociation.first.destroy!
+    end
+
+    assert_instance_of PostWithErrorDestroying, error.record
+  end
+
+  def test_ids_reader_memoization
+    car = Car.create!(name: 'Tofaş')
+    bulb = Bulb.create!(car: car)
+
+    assert_equal [bulb.id], car.bulb_ids
+    assert_no_queries { car.bulb_ids }
+  end
 end
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index 6729a5a9fc..cf730e4fe7 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -84,11 +84,11 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     subscriber   = make_model "Subscriber"
 
     subscriber.primary_key = 'nick'
-    subscription.belongs_to :book,       class: book
-    subscription.belongs_to :subscriber, class: subscriber
+    subscription.belongs_to :book,       anonymous_class: book
+    subscription.belongs_to :subscriber, anonymous_class: subscriber
 
-    book.has_many :subscriptions, class: subscription
-    book.has_many :subscribers, through: :subscriptions, class: subscriber
+    book.has_many :subscriptions, anonymous_class: subscription
+    book.has_many :subscribers, through: :subscriptions, anonymous_class: subscriber
 
     anonbook = book.first
     namebook = Book.find anonbook.id
@@ -154,10 +154,10 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     lesson_student = make_model 'LessonStudent'
     lesson_student.table_name = 'lessons_students'
 
-    lesson_student.belongs_to :lesson, :class => lesson
-    lesson_student.belongs_to :student, :class => student
-    lesson.has_many :lesson_students, :class => lesson_student
-    lesson.has_many :students, :through => :lesson_students, :class => student
+    lesson_student.belongs_to :lesson, :anonymous_class => lesson
+    lesson_student.belongs_to :student, :anonymous_class => student
+    lesson.has_many :lesson_students, :anonymous_class => lesson_student
+    lesson.has_many :students, :through => :lesson_students, :anonymous_class => student
     [lesson, lesson_student, student]
   end
 
@@ -188,7 +188,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
       assert post.people.include?(person)
     end
 
-    assert post.reload.people(true).include?(person)
+    assert post.reload.people.reload.include?(person)
   end
 
   def test_delete_all_for_with_dependent_option_destroy
@@ -229,7 +229,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     post   = posts(:thinking)
     post.people.concat [person]
     assert_equal 1, post.people.size
-    assert_equal 1, post.people(true).size
+    assert_equal 1, post.people.reload.size
   end
 
   def test_associate_existing_record_twice_should_add_to_target_twice
@@ -285,7 +285,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
       assert posts(:thinking).people.include?(new_person)
     end
 
-    assert posts(:thinking).reload.people(true).include?(new_person)
+    assert posts(:thinking).reload.people.reload.include?(new_person)
   end
 
   def test_associate_new_by_building
@@ -310,8 +310,8 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
       posts(:thinking).save
     end
 
-    assert posts(:thinking).reload.people(true).collect(&:first_name).include?("Bob")
-    assert posts(:thinking).reload.people(true).collect(&:first_name).include?("Ted")
+    assert posts(:thinking).reload.people.reload.collect(&:first_name).include?("Bob")
+    assert posts(:thinking).reload.people.reload.collect(&:first_name).include?("Ted")
   end
 
   def test_build_then_save_with_has_many_inverse
@@ -356,7 +356,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
       assert posts(:welcome).people.empty?
     end
 
-    assert posts(:welcome).reload.people(true).empty?
+    assert posts(:welcome).reload.people.reload.empty?
   end
 
   def test_destroy_association
@@ -367,7 +367,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     end
 
     assert posts(:welcome).reload.people.empty?
-    assert posts(:welcome).people(true).empty?
+    assert posts(:welcome).people.reload.empty?
   end
 
   def test_destroy_all
@@ -378,7 +378,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     end
 
     assert posts(:welcome).reload.people.empty?
-    assert posts(:welcome).people(true).empty?
+    assert posts(:welcome).people.reload.empty?
   end
 
   def test_should_raise_exception_for_destroying_mismatching_records
@@ -539,7 +539,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
   end
 
   def test_replace_association
-    assert_queries(4){posts(:welcome);people(:david);people(:michael); posts(:welcome).people(true)}
+    assert_queries(4){posts(:welcome);people(:david);people(:michael); posts(:welcome).people.reload}
 
     # 1 query to delete the existing reader (michael)
     # 1 query to associate the new reader (david)
@@ -552,8 +552,8 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
       assert !posts(:welcome).people.include?(people(:michael))
     }
 
-    assert posts(:welcome).reload.people(true).include?(people(:david))
-    assert !posts(:welcome).reload.people(true).include?(people(:michael))
+    assert posts(:welcome).reload.people.reload.include?(people(:david))
+    assert !posts(:welcome).reload.people.reload.include?(people(:michael))
   end
 
   def test_replace_order_is_preserved
@@ -592,7 +592,13 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
       assert posts(:thinking).people.collect(&:first_name).include?("Jeb")
     end
 
-    assert posts(:thinking).reload.people(true).collect(&:first_name).include?("Jeb")
+    assert posts(:thinking).reload.people.reload.collect(&:first_name).include?("Jeb")
+  end
+
+  def test_through_record_is_built_when_created_with_where
+    assert_difference("posts(:thinking).readers.count", 1) do
+      posts(:thinking).people.where(first_name: "Jeb").create
+    end
   end
 
   def test_associate_with_create_and_no_options
@@ -662,7 +668,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
   end
 
   def test_clear_associations
-    assert_queries(2) { posts(:welcome);posts(:welcome).people(true) }
+    assert_queries(2) { posts(:welcome);posts(:welcome).people.reload }
 
     assert_queries(1) do
       posts(:welcome).people.clear
@@ -672,7 +678,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
       assert posts(:welcome).people.empty?
     end
 
-    assert posts(:welcome).reload.people(true).empty?
+    assert posts(:welcome).reload.people.reload.empty?
   end
 
   def test_association_callback_ordering
@@ -738,13 +744,14 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
 
   def test_get_ids_for_has_many_through_with_conditions_should_not_preload
     Tagging.create!(:taggable_type => 'Post', :taggable_id => posts(:welcome).id, :tag => tags(:misc))
-    ActiveRecord::Associations::Preloader.expects(:new).never
-    posts(:welcome).misc_tag_ids
+    assert_not_called(ActiveRecord::Associations::Preloader, :new) do
+      posts(:welcome).misc_tag_ids
+    end
   end
 
   def test_get_ids_for_loaded_associations
     person = people(:michael)
-    person.posts(true)
+    person.posts.reload
     assert_queries(0) do
       person.post_ids
       person.post_ids
@@ -759,9 +766,10 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
   end
 
   def test_association_proxy_transaction_method_starts_transaction_in_association_class
-    Tag.expects(:transaction)
-    Post.first.tags.transaction do
-      # nothing
+    assert_called(Tag, :transaction) do
+      Post.first.tags.transaction do
+        # nothing
+      end
     end
   end
 
@@ -822,14 +830,14 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     category = author.named_categories.build(:name => "Primary")
     author.save
     assert Categorization.exists?(:author_id => author.id, :named_category_name => category.name)
-    assert author.named_categories(true).include?(category)
+    assert author.named_categories.reload.include?(category)
   end
 
   def test_collection_create_with_nonstandard_primary_key_on_belongs_to
     author   = authors(:mary)
     category = author.named_categories.create(:name => "Primary")
     assert Categorization.exists?(:author_id => author.id, :named_category_name => category.name)
-    assert author.named_categories(true).include?(category)
+    assert author.named_categories.reload.include?(category)
   end
 
   def test_collection_exists
@@ -844,7 +852,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     category = author.named_categories.create(:name => "Primary")
     author.named_categories.delete(category)
     assert !Categorization.exists?(:author_id => author.id, :named_category_name => category.name)
-    assert author.named_categories(true).empty?
+    assert author.named_categories.reload.empty?
   end
 
   def test_collection_singular_ids_getter_with_string_primary_keys
@@ -865,10 +873,10 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     assert_nothing_raised do
       book = books(:awdr)
       book.subscriber_ids = [subscribers(:second).nick]
-      assert_equal [subscribers(:second)], book.subscribers(true)
+      assert_equal [subscribers(:second)], book.subscribers.reload
 
       book.subscriber_ids = []
-      assert_equal [], book.subscribers(true)
+      assert_equal [], book.subscribers.reload
     end
 
   end
@@ -954,7 +962,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     assert_equal 1, category.categorizations.where(:special => true).count
   end
 
-  def test_joining_has_many_through_with_uniq
+  def test_joining_has_many_through_with_distinct
     mary = Author.joins(:unique_categorized_posts).where(:id => authors(:mary).id).first
     assert_equal 1, mary.unique_categorized_posts.length
     assert_equal 1, mary.unique_categorized_post_ids.length
@@ -1034,14 +1042,6 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     end
   end
 
-  def test_save_should_not_raise_exception_when_join_record_has_errors
-    repair_validations(Categorization) do
-      Categorization.validate { |r| r.errors[:base] << 'Invalid Categorization' }
-      c = Category.create(:name => 'Fishing', :authors => [Author.first])
-      c.save
-    end
-  end
-
   def test_assign_array_to_new_record_builds_join_records
     c = Category.new(:name => 'Fishing', :authors => [Author.first])
     assert_equal 1, c.categorizations.size
@@ -1066,11 +1066,11 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     end
   end
 
-  def test_create_bang_returns_falsy_when_join_record_has_errors
+  def test_save_returns_falsy_when_join_record_has_errors
     repair_validations(Categorization) do
       Categorization.validate { |r| r.errors[:base] << 'Invalid Categorization' }
       c = Category.new(:name => 'Fishing', :authors => [Author.first])
-      assert !c.save
+      assert_not c.save
     end
   end
 
@@ -1160,4 +1160,45 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     post_through = organization.posts.build
     assert_equal post_direct.author_id, post_through.author_id
   end
+
+  def test_has_many_through_with_scope_that_should_not_be_fully_merged
+    Club.has_many :distinct_memberships, -> { distinct }, class_name: "Membership"
+    Club.has_many :special_favourites, through: :distinct_memberships, source: :member
+
+    assert_nil Club.new.special_favourites.distinct_value
+  end
+
+  def test_association_force_reload_with_only_true_is_deprecated
+    post = Post.find(1)
+
+    assert_deprecated { post.people(true) }
+  end
+
+  def test_has_many_through_do_not_cache_association_reader_if_the_though_method_has_default_scopes
+    member = Member.create!
+    club = Club.create!
+    TenantMembership.create!(
+      member: member,
+      club: club
+    )
+
+    TenantMembership.current_member = member
+
+    tenant_clubs = member.tenant_clubs
+    assert_equal [club], tenant_clubs
+
+    TenantMembership.current_member = nil
+
+    other_member = Member.create!
+    other_club = Club.create!
+    TenantMembership.create!(
+      member: other_member,
+      club: other_club
+    )
+
+    tenant_clubs = other_member.tenant_clubs
+    assert_equal [other_club], tenant_clubs
+  ensure
+    TenantMembership.current_member = nil
+  end
 end
diff --git a/activerecord/test/cases/associations/has_one_associations_test.rb b/activerecord/test/cases/associations/has_one_associations_test.rb
index 9b6757e256..c9d9e29f09 100644
--- a/activerecord/test/cases/associations/has_one_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_associations_test.rb
@@ -12,7 +12,7 @@ require 'models/image'
 require 'models/post'
 
 class HasOneAssociationsTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
   fixtures :accounts, :companies, :developers, :projects, :developers_projects, :ships, :pirates
 
   def setup
@@ -107,6 +107,14 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     assert_nil Account.find(old_account_id).firm_id
   end
 
+  def test_nullification_on_destroyed_association
+    developer = Developer.create!(name: "Someone")
+    ship = Ship.create!(name: "Planet Caravan", developer: developer)
+    ship.destroy
+    assert !ship.persisted?
+    assert !developer.persisted?
+  end
+
   def test_natural_assignment_to_nil_after_destroy
     firm = companies(:rails_core)
     old_account_id = firm.account.id
@@ -178,6 +186,25 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     assert firm.account.present?
   end
 
+  def test_restrict_with_error_is_deprecated_using_key_one
+    I18n.backend = I18n::Backend::Simple.new
+    I18n.backend.store_translations :en, activerecord: { errors: { messages: { restrict_dependent_destroy: { one: 'message for deprecated key' } } } }
+
+    firm = RestrictedWithErrorFirm.create!(name: 'restrict')
+    firm.create_account(credit_limit: 10)
+
+    assert_not_nil firm.account
+
+    assert_deprecated { firm.destroy }
+
+    assert !firm.errors.empty?
+    assert_equal 'message for deprecated key', firm.errors[:base].first
+    assert RestrictedWithErrorFirm.exists?(name: 'restrict')
+    assert firm.account.present?
+  ensure
+    I18n.backend.reload!
+  end
+
   def test_restrict_with_error
     firm = RestrictedWithErrorFirm.create!(:name => 'restrict')
     firm.create_account(:credit_limit => 10)
@@ -192,6 +219,24 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     assert firm.account.present?
   end
 
+  def test_restrict_with_error_with_locale
+    I18n.backend = I18n::Backend::Simple.new
+    I18n.backend.store_translations 'en', activerecord: {attributes: {restricted_with_error_firm: {account: 'firm account'}}}
+    firm = RestrictedWithErrorFirm.create!(name: 'restrict')
+    firm.create_account(credit_limit: 10)
+
+    assert_not_nil firm.account
+
+    firm.destroy
+
+    assert !firm.errors.empty?
+    assert_equal "Cannot delete record because a dependent firm account exists", firm.errors[:base].first
+    assert RestrictedWithErrorFirm.exists?(name: 'restrict')
+    assert firm.account.present?
+  ensure
+    I18n.backend.reload!
+  end
+
   def test_successful_build_association
     firm = Firm.new("name" => "GlobalMegaCorp")
     firm.save
@@ -237,16 +282,16 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
 
   def test_build_and_create_should_not_happen_within_scope
     pirate = pirates(:blackbeard)
-    scoped_count = pirate.association(:foo_bulb).scope.where_values.count
+    scope = pirate.association(:foo_bulb).scope.where_values_hash
 
     bulb = pirate.build_foo_bulb
-    assert_not_equal scoped_count, bulb.scope_after_initialize.where_values.count
+    assert_not_equal scope, bulb.scope_after_initialize.where_values_hash
 
     bulb = pirate.create_foo_bulb
-    assert_not_equal scoped_count, bulb.scope_after_initialize.where_values.count
+    assert_not_equal scope, bulb.scope_after_initialize.where_values_hash
 
     bulb = pirate.create_foo_bulb!
-    assert_not_equal scoped_count, bulb.scope_after_initialize.where_values.count
+    assert_not_equal scope, bulb.scope_after_initialize.where_values_hash
   end
 
   def test_create_association
@@ -332,7 +377,8 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     assert a.persisted?
     assert_equal a, firm.account
     assert_equal a, firm.account
-    assert_equal a, firm.account(true)
+    firm.association(:account).reload
+    assert_equal a, firm.account
   end
 
   def test_save_still_works_after_accessing_nil_has_one
@@ -607,4 +653,10 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
       end
     end
   end
+
+  def test_association_force_reload_with_only_true_is_deprecated
+    firm = Firm.find(1)
+
+    assert_deprecated { firm.account(true) }
+  end
 end
diff --git a/activerecord/test/cases/associations/has_one_through_associations_test.rb b/activerecord/test/cases/associations/has_one_through_associations_test.rb
index f8772547a2..b2b46812b9 100644
--- a/activerecord/test/cases/associations/has_one_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_through_associations_test.rb
@@ -16,6 +16,10 @@ require 'models/owner'
 require 'models/post'
 require 'models/comment'
 require 'models/categorization'
+require 'models/customer'
+require 'models/carrier'
+require 'models/shop_account'
+require 'models/customer_carrier'
 
 class HasOneThroughAssociationsTest < ActiveRecord::TestCase
   fixtures :member_types, :members, :clubs, :memberships, :sponsors, :organizations, :minivans,
@@ -245,12 +249,14 @@ class HasOneThroughAssociationsTest < ActiveRecord::TestCase
     assert_not_nil @member_detail.member_type
     @member_detail.destroy
     assert_queries(1) do
-      assert_not_nil @member_detail.member_type(true)
+      @member_detail.association(:member_type).reload
+      assert_not_nil @member_detail.member_type
     end
 
     @member_detail.member.destroy
     assert_queries(1) do
-      assert_nil @member_detail.member_type(true)
+      @member_detail.association(:member_type).reload
+      assert_nil @member_detail.member_type
     end
   end
 
@@ -344,4 +350,34 @@ class HasOneThroughAssociationsTest < ActiveRecord::TestCase
       end
     end
   end
+
+  def test_has_one_through_do_not_cache_association_reader_if_the_though_method_has_default_scopes
+    customer = Customer.create!
+    carrier = Carrier.create!
+    customer_carrier = CustomerCarrier.create!(
+      customer: customer,
+      carrier: carrier,
+    )
+    account = ShopAccount.create!(customer_carrier: customer_carrier)
+
+    CustomerCarrier.current_customer = customer
+
+    account_carrier = account.carrier
+    assert_equal carrier, account_carrier
+
+    CustomerCarrier.current_customer = nil
+
+    other_carrier = Carrier.create!
+    other_customer = Customer.create!
+    other_customer_carrier = CustomerCarrier.create!(
+      customer: other_customer,
+      carrier: other_carrier,
+    )
+    other_account = ShopAccount.create!(customer_carrier: other_customer_carrier)
+
+    account_carrier = other_account.carrier
+    assert_equal other_carrier, account_carrier
+  ensure
+    CustomerCarrier.current_customer = nil
+  end
 end
diff --git a/activerecord/test/cases/associations/inverse_associations_test.rb b/activerecord/test/cases/associations/inverse_associations_test.rb
index 423b8238b1..57d1c8feda 100644
--- a/activerecord/test/cases/associations/inverse_associations_test.rb
+++ b/activerecord/test/cases/associations/inverse_associations_test.rb
@@ -13,6 +13,9 @@ require 'models/mixed_case_monkey'
 require 'models/admin'
 require 'models/admin/account'
 require 'models/admin/user'
+require 'models/developer'
+require 'models/company'
+require 'models/project'
 
 class AutomaticInverseFindingTests < ActiveRecord::TestCase
   fixtures :ratings, :comments, :cars
@@ -80,10 +83,10 @@ class AutomaticInverseFindingTests < ActiveRecord::TestCase
 
     assert_equal rating.comment, comment, "The Rating's comment should be the original Comment"
 
-    rating.comment.body = "Brogramming is the act of programming, like a bro."
+    rating.comment.body = "Fennec foxes are the smallest of the foxes."
     assert_equal rating.comment.body, comment.body, "Changing the Comment's body on the association should change the original Comment's body"
 
-    comment.body = "Broseiden is the king of the sea of bros."
+    comment.body = "Kittens are adorable."
     assert_equal comment.body, rating.comment.body, "Changing the original Comment's body should change the Comment's body on the association"
   end
 
@@ -94,10 +97,10 @@ class AutomaticInverseFindingTests < ActiveRecord::TestCase
 
     assert_equal rating.comment, comment, "The Rating's comment should be the original Comment"
 
-    rating.comment.body = "Brogramming is the act of programming, like a bro."
+    rating.comment.body = "Fennec foxes are the smallest of the foxes."
     assert_equal rating.comment.body, comment.body, "Changing the Comment's body on the association should change the original Comment's body"
 
-    comment.body = "Broseiden is the king of the sea of bros."
+    comment.body = "Kittens are adorable."
     assert_equal comment.body, rating.comment.body, "Changing the original Comment's body should change the Comment's body on the association"
   end
 
@@ -198,6 +201,16 @@ class InverseAssociationTests < ActiveRecord::TestCase
     belongs_to_ref = Sponsor.reflect_on_association(:sponsor_club)
     assert_nil belongs_to_ref.inverse_of
   end
+
+  def test_this_inverse_stuff
+    firm = Firm.create!(name: 'Adequate Holdings')
+    Project.create!(name: 'Project 1', firm: firm)
+    Developer.create!(name: 'Gorbypuff', firm: firm)
+
+    new_project = Project.last
+    assert Project.reflect_on_association(:lead_developer).inverse_of.present?, "Expected inverse of to be present"
+    assert new_project.lead_developer.present?, "Expected lead developer to be present on the project"
+  end
 end
 
 class InverseHasOneTests < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/associations/join_model_test.rb b/activerecord/test/cases/associations/join_model_test.rb
index 9918601623..f6dddaf5b4 100644
--- a/activerecord/test/cases/associations/join_model_test.rb
+++ b/activerecord/test/cases/associations/join_model_test.rb
@@ -17,7 +17,7 @@ require 'models/engine'
 require 'models/car'
 
 class AssociationsJoinModelTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   fixtures :posts, :authors, :categories, :categorizations, :comments, :tags, :taggings, :author_favorites, :vertices, :items, :books,
     # Reload edges table from fixtures as otherwise repeated test was failing
@@ -35,12 +35,12 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert categories(:sti_test).authors.include?(authors(:mary))
   end
 
-  def test_has_many_uniq_through_join_model
+  def test_has_many_distinct_through_join_model
     assert_equal 2, authors(:mary).categorized_posts.size
     assert_equal 1, authors(:mary).unique_categorized_posts.size
   end
 
-  def test_has_many_uniq_through_count
+  def test_has_many_distinct_through_count
     author = authors(:mary)
     assert !authors(:mary).unique_categorized_posts.loaded?
     assert_queries(1) { assert_equal 1, author.unique_categorized_posts.count }
@@ -49,7 +49,7 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert !authors(:mary).unique_categorized_posts.loaded?
   end
 
-  def test_has_many_uniq_through_find
+  def test_has_many_distinct_through_find
     assert_equal 1, authors(:mary).unique_categorized_posts.to_a.size
   end
 
@@ -213,7 +213,8 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     old_count = Tagging.count
     post.destroy
     assert_equal old_count-1, Tagging.count
-    assert_nil posts(:welcome).tagging(true)
+    posts(:welcome).association(:tagging).reload
+    assert_nil posts(:welcome).tagging
   end
 
   def test_delete_polymorphic_has_one_with_nullify
@@ -224,7 +225,8 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     old_count = Tagging.count
     post.destroy
     assert_equal old_count, Tagging.count
-    assert_nil posts(:welcome).tagging(true)
+    posts(:welcome).association(:tagging).reload
+    assert_nil posts(:welcome).tagging
   end
 
   def test_has_many_with_piggyback
@@ -461,7 +463,7 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert saved_post.tags.include?(new_tag)
 
     assert new_tag.persisted?
-    assert saved_post.reload.tags(true).include?(new_tag)
+    assert saved_post.reload.tags.reload.include?(new_tag)
 
 
     new_post = Post.new(:title => "Association replacement works!", :body => "You best believe it.")
@@ -474,7 +476,7 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
 
     new_post.save!
     assert new_post.persisted?
-    assert new_post.reload.tags(true).include?(saved_tag)
+    assert new_post.reload.tags.reload.include?(saved_tag)
 
     assert !posts(:thinking).tags.build.persisted?
     assert !posts(:thinking).tags.new.persisted?
@@ -490,7 +492,7 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert_nil( wrong = post_thinking.taggings.detect { |t| t.class != Tagging },
                 message = "Expected a Tagging in taggings collection, got #{wrong.class}.")
     assert_equal(count + 1, post_thinking.reload.tags.size)
-    assert_equal(count + 1, post_thinking.tags(true).size)
+    assert_equal(count + 1, post_thinking.tags.reload.size)
 
     assert_kind_of Tag, post_thinking.tags.create!(:name => 'foo')
     assert_nil( wrong = post_thinking.tags.detect { |t| t.class != Tag },
@@ -498,7 +500,7 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert_nil( wrong = post_thinking.taggings.detect { |t| t.class != Tagging },
                 message = "Expected a Tagging in taggings collection, got #{wrong.class}.")
     assert_equal(count + 2, post_thinking.reload.tags.size)
-    assert_equal(count + 2, post_thinking.tags(true).size)
+    assert_equal(count + 2, post_thinking.tags.reload.size)
 
     assert_nothing_raised { post_thinking.tags.concat(Tag.create!(:name => 'abc'), Tag.create!(:name => 'def')) }
     assert_nil( wrong = post_thinking.tags.detect { |t| t.class != Tag },
@@ -506,7 +508,7 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert_nil( wrong = post_thinking.taggings.detect { |t| t.class != Tagging },
                 message = "Expected a Tagging in taggings collection, got #{wrong.class}.")
     assert_equal(count + 4, post_thinking.reload.tags.size)
-    assert_equal(count + 4, post_thinking.tags(true).size)
+    assert_equal(count + 4, post_thinking.tags.reload.size)
 
     # Raises if the wrong reflection name is used to set the Edge belongs_to
     assert_nothing_raised { vertices(:vertex_1).sinks << vertices(:vertex_5) }
@@ -544,11 +546,11 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     book = Book.create!(:name => 'Getting Real')
     book_awdr = books(:awdr)
     book_awdr.references << book
-    assert_equal(count + 1, book_awdr.references(true).size)
+    assert_equal(count + 1, book_awdr.references.reload.size)
 
     assert_nothing_raised { book_awdr.references.delete(book) }
     assert_equal(count, book_awdr.references.size)
-    assert_equal(count, book_awdr.references(true).size)
+    assert_equal(count, book_awdr.references.reload.size)
     assert_equal(references_before.sort, book_awdr.references.sort)
   end
 
@@ -558,14 +560,14 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     tag = Tag.create!(:name => 'doomed')
     post_thinking = posts(:thinking)
     post_thinking.tags << tag
-    assert_equal(count + 1, post_thinking.taggings(true).size)
-    assert_equal(count + 1, post_thinking.reload.tags(true).size)
+    assert_equal(count + 1, post_thinking.taggings.reload.size)
+    assert_equal(count + 1, post_thinking.reload.tags.reload.size)
     assert_not_equal(tags_before, post_thinking.tags.sort)
 
     assert_nothing_raised { post_thinking.tags.delete(tag) }
     assert_equal(count, post_thinking.tags.size)
-    assert_equal(count, post_thinking.tags(true).size)
-    assert_equal(count, post_thinking.taggings(true).size)
+    assert_equal(count, post_thinking.tags.reload.size)
+    assert_equal(count, post_thinking.taggings.reload.size)
     assert_equal(tags_before, post_thinking.tags.sort)
   end
 
@@ -577,11 +579,11 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     quaked = Tag.create!(:name => 'quaked')
     post_thinking = posts(:thinking)
     post_thinking.tags << doomed << doomed2
-    assert_equal(count + 2, post_thinking.reload.tags(true).size)
+    assert_equal(count + 2, post_thinking.reload.tags.reload.size)
 
     assert_nothing_raised { post_thinking.tags.delete(doomed, doomed2, quaked) }
     assert_equal(count, post_thinking.tags.size)
-    assert_equal(count, post_thinking.tags(true).size)
+    assert_equal(count, post_thinking.tags.reload.size)
     assert_equal(tags_before, post_thinking.tags.sort)
   end
 
@@ -625,7 +627,7 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert_equal [comments(:does_it_hurt)], authors(:david).special_post_comments
   end
 
-  def test_uniq_has_many_through_should_retain_order
+  def test_distinct_has_many_through_should_retain_order
     comment_ids = authors(:david).comments.map(&:id)
     assert_equal comment_ids.sort, authors(:david).ordered_uniq_comments.map(&:id)
     assert_equal comment_ids.sort.reverse, authors(:david).ordered_uniq_comments_desc.map(&:id)
diff --git a/activerecord/test/cases/associations/nested_through_associations_test.rb b/activerecord/test/cases/associations/nested_through_associations_test.rb
index 31b68c940e..b040485d99 100644
--- a/activerecord/test/cases/associations/nested_through_associations_test.rb
+++ b/activerecord/test/cases/associations/nested_through_associations_test.rb
@@ -495,7 +495,7 @@ class NestedThroughAssociationsTest < ActiveRecord::TestCase
     groucho = members(:groucho)
     founding = member_types(:founding)
 
-    assert_raises(ActiveRecord::HasManyThroughNestedAssociationsAreReadonly) do
+    assert_raises(ActiveRecord::HasOneThroughNestedAssociationsAreReadonly) do
       groucho.nested_member_type = founding
     end
   end
diff --git a/activerecord/test/cases/associations/required_test.rb b/activerecord/test/cases/associations/required_test.rb
index 321fb6c8dd..3e5494e897 100644
--- a/activerecord/test/cases/associations/required_test.rb
+++ b/activerecord/test/cases/associations/required_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 
 class RequiredAssociationsTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   class Parent < ActiveRecord::Base
   end
@@ -18,8 +18,8 @@ class RequiredAssociationsTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.drop_table 'parents' if @connection.table_exists? 'parents'
-    @connection.drop_table 'children' if @connection.table_exists? 'children'
+    @connection.drop_table 'parents', if_exists: true
+    @connection.drop_table 'children', if_exists: true
   end
 
   test "belongs_to associations are not required by default" do
@@ -40,7 +40,7 @@ class RequiredAssociationsTest < ActiveRecord::TestCase
 
     record = model.new
     assert_not record.save
-    assert_equal ["Parent can't be blank"], record.errors.full_messages
+    assert_equal ["Parent must exist"], record.errors.full_messages
 
     record.parent = Parent.new
     assert record.save
@@ -64,12 +64,32 @@ class RequiredAssociationsTest < ActiveRecord::TestCase
 
     record = model.new
     assert_not record.save
-    assert_equal ["Child can't be blank"], record.errors.full_messages
+    assert_equal ["Child must exist"], record.errors.full_messages
 
     record.child = Child.new
     assert record.save
   end
 
+  test "required has_one associations have a correct error message" do
+    model = subclass_of(Parent) do
+      has_one :child, required: true, inverse_of: false,
+      class_name: "RequiredAssociationsTest::Child"
+    end
+
+    record = model.create
+    assert_equal ["Child must exist"], record.errors.full_messages
+  end
+
+  test "required belongs_to associations have a correct error message" do
+    model = subclass_of(Child) do
+      belongs_to :parent, required: true, inverse_of: false,
+      class_name: "RequiredAssociationsTest::Parent"
+    end
+
+    record = model.create
+    assert_equal ["Parent must exist"], record.errors.full_messages
+  end
+
   private
 
   def subclass_of(klass, &block)
diff --git a/activerecord/test/cases/associations_test.rb b/activerecord/test/cases/associations_test.rb
index 72963fd56c..01a058918a 100644
--- a/activerecord/test/cases/associations_test.rb
+++ b/activerecord/test/cases/associations_test.rb
@@ -1,7 +1,6 @@
 require "cases/helper"
 require 'models/computer'
 require 'models/developer'
-require 'models/computer'
 require 'models/project'
 require 'models/company'
 require 'models/categorization'
@@ -13,7 +12,6 @@ require 'models/tag'
 require 'models/tagging'
 require 'models/person'
 require 'models/reader'
-require 'models/parrot'
 require 'models/ship_part'
 require 'models/ship'
 require 'models/liquid'
@@ -43,28 +41,6 @@ class AssociationsTest < ActiveRecord::TestCase
     assert_equal favs, fav2
   end
 
-  def test_clear_association_cache_stored
-    firm = Firm.find(1)
-    assert_kind_of Firm, firm
-
-    firm.clear_association_cache
-    assert_equal Firm.find(1).clients.collect(&:name).sort, firm.clients.collect(&:name).sort
-  end
-
-  def test_clear_association_cache_new_record
-     firm            = Firm.new
-     client_stored   = Client.find(3)
-     client_new      = Client.new
-     client_new.name = "The Joneses"
-     clients         = [ client_stored, client_new ]
-
-     firm.clients    << clients
-     assert_equal clients.map(&:name).to_set, firm.clients.map(&:name).to_set
-
-     firm.clear_association_cache
-     assert_equal clients.map(&:name).to_set, firm.clients.map(&:name).to_set
-  end
-
   def test_loading_the_association_target_should_keep_child_records_marked_for_destruction
     ship = Ship.create!(:name => "The good ship Dollypop")
     part = ship.parts.create!(:name => "Mast")
@@ -115,8 +91,10 @@ class AssociationsTest < ActiveRecord::TestCase
     assert firm.clients.empty?, "New firm should have cached no client objects"
     assert_equal 0, firm.clients.size, "New firm should have cached 0 clients count"
 
-    assert !firm.clients(true).empty?, "New firm should have reloaded client objects"
-    assert_equal 1, firm.clients(true).size, "New firm should have reloaded clients count"
+    ActiveSupport::Deprecation.silence do
+      assert !firm.clients(true).empty?, "New firm should have reloaded client objects"
+      assert_equal 1, firm.clients(true).size, "New firm should have reloaded clients count"
+    end
   end
 
   def test_using_limitable_reflections_helper
@@ -132,16 +110,19 @@ class AssociationsTest < ActiveRecord::TestCase
   def test_force_reload_is_uncached
     firm = Firm.create!("name" => "A New Firm, Inc")
     Client.create!("name" => "TheClient.com", :firm => firm)
-    ActiveRecord::Base.cache do
-      firm.clients.each {}
-      assert_queries(0) { assert_not_nil firm.clients.each {} }
-      assert_queries(1) { assert_not_nil firm.clients(true).each {} }
+
+    ActiveSupport::Deprecation.silence do
+      ActiveRecord::Base.cache do
+        firm.clients.each {}
+        assert_queries(0) { assert_not_nil firm.clients.each {} }
+        assert_queries(1) { assert_not_nil firm.clients(true).each {} }
+      end
     end
   end
 
   def test_association_with_references
     firm = companies(:first_firm)
-    assert_equal ['foo'], firm.association_with_references.references_values
+    assert_includes firm.association_with_references.references_values, 'foo'
   end
 
 end
@@ -238,7 +219,7 @@ class AssociationProxyTest < ActiveRecord::TestCase
   end
 
   def test_scoped_allows_conditions
-    assert developers(:david).projects.merge!(where: 'foo').where_values.include?('foo')
+    assert developers(:david).projects.merge(where: 'foo').to_sql.include?('foo')
   end
 
   test "getting a scope from an association" do
diff --git a/activerecord/test/cases/attribute_decorators_test.rb b/activerecord/test/cases/attribute_decorators_test.rb
index 53bd58e22e..2aeb2601c2 100644
--- a/activerecord/test/cases/attribute_decorators_test.rb
+++ b/activerecord/test/cases/attribute_decorators_test.rb
@@ -12,11 +12,11 @@ module ActiveRecord
         super(delegate)
       end
 
-      def type_cast_from_user(value)
+      def cast(value)
         "#{super} #{@decoration}"
       end
 
-      alias type_cast_from_database type_cast_from_user
+      alias deserialize cast
     end
 
     setup do
@@ -28,7 +28,7 @@ module ActiveRecord
 
     teardown do
       return unless @connection
-      @connection.drop_table 'attribute_decorators_model' if @connection.table_exists? 'attribute_decorators_model'
+      @connection.drop_table 'attribute_decorators_model', if_exists: true
       Model.attribute_type_decorations.clear
       Model.reset_column_information
     end
@@ -51,7 +51,7 @@ module ActiveRecord
     end
 
     test "undecorated columns are not touched" do
-      Model.attribute :another_string, Type::String.new, default: 'something or other'
+      Model.attribute :another_string, :string, default: 'something or other'
       Model.decorate_attribute_type(:a_string, :test) { |t| StringDecorator.new(t) }
 
       assert_equal 'something or other', Model.new.another_string
@@ -86,7 +86,7 @@ module ActiveRecord
     end
 
     test "decorating attributes does not modify parent classes" do
-      Model.attribute :another_string, Type::String.new, default: 'whatever'
+      Model.attribute :another_string, :string, default: 'whatever'
       Model.decorate_attribute_type(:a_string, :test) { |t| StringDecorator.new(t) }
       child_class = Class.new(Model)
       child_class.decorate_attribute_type(:another_string, :test) { |t| StringDecorator.new(t) }
@@ -102,15 +102,15 @@ module ActiveRecord
     end
 
     class Multiplier < SimpleDelegator
-      def type_cast_from_user(value)
+      def cast(value)
         return if value.nil?
         value * 2
       end
-      alias type_cast_from_database type_cast_from_user
+      alias deserialize cast
     end
 
     test "decorating with a proc" do
-      Model.attribute :an_int, Type::Integer.new
+      Model.attribute :an_int, :integer
       type_is_integer = proc { |_, type| type.type == :integer }
       Model.decorate_matching_attribute_types type_is_integer, :multiplier do |type|
         Multiplier.new(type)
diff --git a/activerecord/test/cases/attribute_methods/read_test.rb b/activerecord/test/cases/attribute_methods/read_test.rb
index e38b32d7fc..74e556211b 100644
--- a/activerecord/test/cases/attribute_methods/read_test.rb
+++ b/activerecord/test/cases/attribute_methods/read_test.rb
@@ -17,7 +17,7 @@ module ActiveRecord
 
           include ActiveRecord::AttributeMethods
 
-          def self.column_names
+          def self.attribute_names
             %w{ one two three }
           end
 
@@ -25,11 +25,11 @@ module ActiveRecord
           end
 
           def self.columns
-            column_names.map { FakeColumn.new(name) }
+            attribute_names.map { FakeColumn.new(name) }
           end
 
           def self.columns_hash
-            Hash[column_names.map { |name|
+            Hash[attribute_names.map { |name|
               [name, FakeColumn.new(name)]
             }]
           end
@@ -39,13 +39,13 @@ module ActiveRecord
       def test_define_attribute_methods
         instance = @klass.new
 
-        @klass.column_names.each do |name|
+        @klass.attribute_names.each do |name|
           assert !instance.methods.map(&:to_s).include?(name)
         end
 
         @klass.define_attribute_methods
 
-        @klass.column_names.each do |name|
+        @klass.attribute_names.each do |name|
           assert instance.methods.map(&:to_s).include?(name), "#{name} is not defined"
         end
       end
diff --git a/activerecord/test/cases/attribute_methods_test.rb b/activerecord/test/cases/attribute_methods_test.rb
index 4036294121..52d197718e 100644
--- a/activerecord/test/cases/attribute_methods_test.rb
+++ b/activerecord/test/cases/attribute_methods_test.rb
@@ -1,7 +1,6 @@
 require "cases/helper"
 require 'models/minimalistic'
 require 'models/developer'
-require 'models/computer'
 require 'models/auto_id'
 require 'models/boolean'
 require 'models/computer'
@@ -67,8 +66,9 @@ class AttributeMethodsTest < ActiveRecord::TestCase
 
   def test_caching_nil_primary_key
     klass = Class.new(Minimalistic)
-    klass.expects(:reset_primary_key).returns(nil).once
-    2.times { klass.primary_key }
+    assert_called(klass, :reset_primary_key, returns: nil) do
+      2.times { klass.primary_key }
+    end
   end
 
   def test_attribute_keys_on_new_instance
@@ -175,9 +175,9 @@ class AttributeMethodsTest < ActiveRecord::TestCase
     assert_equal category_attrs , category.attributes_before_type_cast
   end
 
-  if current_adapter?(:MysqlAdapter)
+  if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
     def test_read_attributes_before_type_cast_on_boolean
-      bool = Boolean.create({ "value" => false })
+      bool = Boolean.create!({ "value" => false })
       if RUBY_PLATFORM =~ /java/
         # JRuby will return the value before typecast as string
         assert_equal "0", bool.reload.attributes_before_type_cast["value"]
@@ -542,9 +542,6 @@ class AttributeMethodsTest < ActiveRecord::TestCase
 
     developer.save!
 
-    assert_equal "50000", developer.salary_before_type_cast
-    assert_equal 1337, developer.name_before_type_cast
-
     assert_equal 50000, developer.salary
     assert_equal "1337", developer.name
   end
@@ -937,6 +934,16 @@ class AttributeMethodsTest < ActiveRecord::TestCase
     assert model.id_came_from_user?
   end
 
+  def test_accessed_fields
+    model = @target.first
+
+    assert_equal [], model.accessed_fields
+
+    model.title
+
+    assert_equal ["title"], model.accessed_fields
+  end
+
   private
 
   def new_topic_like_ar_class(&block)
diff --git a/activerecord/test/cases/attribute_set_test.rb b/activerecord/test/cases/attribute_set_test.rb
index ba53612d30..7a24b85a36 100644
--- a/activerecord/test/cases/attribute_set_test.rb
+++ b/activerecord/test/cases/attribute_set_test.rb
@@ -29,7 +29,7 @@ module ActiveRecord
       assert_equal :bar, attributes[:bar].name
     end
 
-    test "duping creates a new hash and dups each attribute" do
+    test "duping creates a new hash, but does not dup the attributes" do
       builder = AttributeSet::Builder.new(foo: Type::Integer.new, bar: Type::String.new)
       attributes = builder.build_from_database(foo: 1, bar: 'foo')
 
@@ -43,6 +43,24 @@ module ActiveRecord
 
       assert_equal 1, attributes[:foo].value
       assert_equal 2, duped[:foo].value
+      assert_equal 'foobar', attributes[:bar].value
+      assert_equal 'foobar', duped[:bar].value
+    end
+
+    test "deep_duping creates a new hash and dups each attribute" do
+      builder = AttributeSet::Builder.new(foo: Type::Integer.new, bar: Type::String.new)
+      attributes = builder.build_from_database(foo: 1, bar: 'foo')
+
+      # Ensure the type cast value is cached
+      attributes[:foo].value
+      attributes[:bar].value
+
+      duped = attributes.deep_dup
+      duped.write_from_database(:foo, 2)
+      duped[:bar].value << 'bar'
+
+      assert_equal 1, attributes[:foo].value
+      assert_equal 2, duped[:foo].value
       assert_equal 'foo', attributes[:bar].value
       assert_equal 'foobar', duped[:bar].value
     end
@@ -65,6 +83,16 @@ module ActiveRecord
       assert_equal({ foo: 1, bar: 2.2 }, attributes.to_h)
     end
 
+    test "to_hash maintains order" do
+      builder = AttributeSet::Builder.new(foo: Type::Integer.new, bar: Type::Float.new)
+      attributes = builder.build_from_database(foo: '2.2', bar: '3.3')
+
+      attributes[:bar]
+      hash = attributes.to_h
+
+      assert_equal [[:foo, 2], [:bar, 3.3]], hash.to_a
+    end
+
     test "values_before_type_cast" do
       builder = AttributeSet::Builder.new(foo: Type::Integer.new, bar: Type::Integer.new)
       attributes = builder.build_from_database(foo: '1.1', bar: '2.2')
@@ -141,15 +169,18 @@ module ActiveRecord
     end
 
     class MyType
-      def type_cast_from_user(value)
+      def cast(value)
         return if value.nil?
         value + " from user"
       end
 
-      def type_cast_from_database(value)
+      def deserialize(value)
         return if value.nil?
         value + " from database"
       end
+
+      def assert_valid_value(*)
+      end
     end
 
     test "write_from_database sets the attribute with database typecasting" do
@@ -186,5 +217,37 @@ module ActiveRecord
       attributes.freeze
       assert_equal({ foo: "1" }, attributes.to_hash)
     end
+
+    test "#accessed_attributes returns only attributes which have been read" do
+      builder = AttributeSet::Builder.new(foo: Type::Value.new, bar: Type::Value.new)
+      attributes = builder.build_from_database(foo: "1", bar: "2")
+
+      assert_equal [], attributes.accessed
+
+      attributes.fetch_value(:foo)
+
+      assert_equal [:foo], attributes.accessed
+    end
+
+    test "#map returns a new attribute set with the changes applied" do
+      builder = AttributeSet::Builder.new(foo: Type::Integer.new, bar: Type::Integer.new)
+      attributes = builder.build_from_database(foo: "1", bar: "2")
+      new_attributes = attributes.map do |attr|
+        attr.with_cast_value(attr.value + 1)
+      end
+
+      assert_equal 2, new_attributes.fetch_value(:foo)
+      assert_equal 3, new_attributes.fetch_value(:bar)
+    end
+
+    test "comparison for equality is correctly implemented" do
+      builder = AttributeSet::Builder.new(foo: Type::Integer.new, bar: Type::Integer.new)
+      attributes = builder.build_from_database(foo: "1", bar: "2")
+      attributes2 = builder.build_from_database(foo: "1", bar: "2")
+      attributes3 = builder.build_from_database(foo: "2", bar: "2")
+
+      assert_equal attributes, attributes2
+      assert_not_equal attributes2, attributes3
+    end
   end
 end
diff --git a/activerecord/test/cases/attribute_test.rb b/activerecord/test/cases/attribute_test.rb
index 39a976fcc8..a24a4fc6a4 100644
--- a/activerecord/test/cases/attribute_test.rb
+++ b/activerecord/test/cases/attribute_test.rb
@@ -1,11 +1,9 @@
 require 'cases/helper'
-require 'minitest/mock'
 
 module ActiveRecord
   class AttributeTest < ActiveRecord::TestCase
     setup do
       @type = Minitest::Mock.new
-      @type.expect(:==, false, [false])
     end
 
     teardown do
@@ -13,7 +11,7 @@ module ActiveRecord
     end
 
     test "from_database + read type casts from database" do
-      @type.expect(:type_cast_from_database, 'type cast from database', ['a value'])
+      @type.expect(:deserialize, 'type cast from database', ['a value'])
       attribute = Attribute.from_database(nil, 'a value', @type)
 
       type_cast_value = attribute.value
@@ -22,7 +20,7 @@ module ActiveRecord
     end
 
     test "from_user + read type casts from user" do
-      @type.expect(:type_cast_from_user, 'type cast from user', ['a value'])
+      @type.expect(:cast, 'type cast from user', ['a value'])
       attribute = Attribute.from_user(nil, 'a value', @type)
 
       type_cast_value = attribute.value
@@ -31,7 +29,7 @@ module ActiveRecord
     end
 
     test "reading memoizes the value" do
-      @type.expect(:type_cast_from_database, 'from the database', ['whatever'])
+      @type.expect(:deserialize, 'from the database', ['whatever'])
       attribute = Attribute.from_database(nil, 'whatever', @type)
 
       type_cast_value = attribute.value
@@ -42,7 +40,7 @@ module ActiveRecord
     end
 
     test "reading memoizes falsy values" do
-      @type.expect(:type_cast_from_database, false, ['whatever'])
+      @type.expect(:deserialize, false, ['whatever'])
       attribute = Attribute.from_database(nil, 'whatever', @type)
 
       attribute.value
@@ -58,27 +56,27 @@ module ActiveRecord
     end
 
     test "from_database + read_for_database type casts to and from database" do
-      @type.expect(:type_cast_from_database, 'read from database', ['whatever'])
-      @type.expect(:type_cast_for_database, 'ready for database', ['read from database'])
+      @type.expect(:deserialize, 'read from database', ['whatever'])
+      @type.expect(:serialize, 'ready for database', ['read from database'])
       attribute = Attribute.from_database(nil, 'whatever', @type)
 
-      type_cast_for_database = attribute.value_for_database
+      serialize = attribute.value_for_database
 
-      assert_equal 'ready for database', type_cast_for_database
+      assert_equal 'ready for database', serialize
     end
 
     test "from_user + read_for_database type casts from the user to the database" do
-      @type.expect(:type_cast_from_user, 'read from user', ['whatever'])
-      @type.expect(:type_cast_for_database, 'ready for database', ['read from user'])
+      @type.expect(:cast, 'read from user', ['whatever'])
+      @type.expect(:serialize, 'ready for database', ['read from user'])
       attribute = Attribute.from_user(nil, 'whatever', @type)
 
-      type_cast_for_database = attribute.value_for_database
+      serialize = attribute.value_for_database
 
-      assert_equal 'ready for database', type_cast_for_database
+      assert_equal 'ready for database', serialize
     end
 
     test "duping dups the value" do
-      @type.expect(:type_cast_from_database, 'type cast', ['a value'])
+      @type.expect(:deserialize, 'type cast', ['a value'])
       attribute = Attribute.from_database(nil, 'a value', @type)
 
       value_from_orig = attribute.value
@@ -90,7 +88,7 @@ module ActiveRecord
     end
 
     test "duping does not dup the value if it is not dupable" do
-      @type.expect(:type_cast_from_database, false, ['a value'])
+      @type.expect(:deserialize, false, ['a value'])
       attribute = Attribute.from_database(nil, 'a value', @type)
 
       assert_same attribute.value, attribute.dup.value
@@ -102,13 +100,16 @@ module ActiveRecord
     end
 
     class MyType
-      def type_cast_from_user(value)
+      def cast(value)
         value + " from user"
       end
 
-      def type_cast_from_database(value)
+      def deserialize(value)
         value + " from database"
       end
+
+      def assert_valid_value(*)
+      end
     end
 
     test "with_value_from_user returns a new attribute with the value from the user" do
@@ -169,5 +170,77 @@ module ActiveRecord
       second = Attribute.from_user(:foo, 1, Type::Integer.new)
       assert_not_equal first, second
     end
+
+    test "an attribute has not been read by default" do
+      attribute = Attribute.from_database(:foo, 1, Type::Value.new)
+      assert_not attribute.has_been_read?
+    end
+
+    test "an attribute has been read when its value is calculated" do
+      attribute = Attribute.from_database(:foo, 1, Type::Value.new)
+      attribute.value
+      assert attribute.has_been_read?
+    end
+
+    test "an attribute is not changed if it hasn't been assigned or mutated" do
+      attribute = Attribute.from_database(:foo, 1, Type::Value.new)
+
+      refute attribute.changed?
+    end
+
+    test "an attribute is changed if it's been assigned a new value" do
+      attribute = Attribute.from_database(:foo, 1, Type::Value.new)
+      changed = attribute.with_value_from_user(2)
+
+      assert changed.changed?
+    end
+
+    test "an attribute is not changed if it's assigned the same value" do
+      attribute = Attribute.from_database(:foo, 1, Type::Value.new)
+      unchanged = attribute.with_value_from_user(1)
+
+      refute unchanged.changed?
+    end
+
+    test "an attribute can not be mutated if it has not been read,
+      and skips expensive calculations" do
+      type_which_raises_from_all_methods = Object.new
+      attribute = Attribute.from_database(:foo, "bar", type_which_raises_from_all_methods)
+
+      assert_not attribute.changed_in_place?
+    end
+
+    test "an attribute is changed if it has been mutated" do
+      attribute = Attribute.from_database(:foo, "bar", Type::String.new)
+      attribute.value << "!"
+
+      assert attribute.changed_in_place?
+      assert attribute.changed?
+    end
+
+    test "an attribute can forget its changes" do
+      attribute = Attribute.from_database(:foo, "bar", Type::String.new)
+      changed = attribute.with_value_from_user("foo")
+      forgotten = changed.forgetting_assignment
+
+      assert changed.changed? # sanity check
+      refute forgotten.changed?
+    end
+
+    test "with_value_from_user validates the value" do
+      type = Type::Value.new
+      type.define_singleton_method(:assert_valid_value) do |value|
+        if value == 1
+          raise ArgumentError
+        end
+      end
+
+      attribute = Attribute.from_database(:foo, 1, type)
+      assert_equal 1, attribute.value
+      assert_equal 2, attribute.with_value_from_user(2).value
+      assert_raises ArgumentError do
+        attribute.with_value_from_user(1)
+      end
+    end
   end
 end
diff --git a/activerecord/test/cases/attributes_test.rb b/activerecord/test/cases/attributes_test.rb
index dbe1eb48db..264b275181 100644
--- a/activerecord/test/cases/attributes_test.rb
+++ b/activerecord/test/cases/attributes_test.rb
@@ -1,17 +1,17 @@
 require 'cases/helper'
 
 class OverloadedType < ActiveRecord::Base
-  attribute :overloaded_float, Type::Integer.new
-  attribute :overloaded_string_with_limit, Type::String.new(limit: 50)
-  attribute :non_existent_decimal, Type::Decimal.new
-  attribute :string_with_default, Type::String.new, default: 'the overloaded default'
+  attribute :overloaded_float, :integer
+  attribute :overloaded_string_with_limit, :string, limit: 50
+  attribute :non_existent_decimal, :decimal
+  attribute :string_with_default, :string, default: 'the overloaded default'
 end
 
 class ChildOfOverloadedType < OverloadedType
 end
 
 class GrandchildOfOverloadedType < ChildOfOverloadedType
-  attribute :overloaded_float, Type::Float.new
+  attribute :overloaded_float, :float
 end
 
 class UnoverloadedType < ActiveRecord::Base
@@ -50,8 +50,8 @@ module ActiveRecord
     end
 
     test "overloaded properties with limit" do
-      assert_equal 50, OverloadedType.columns_hash['overloaded_string_with_limit'].limit
-      assert_equal 255, UnoverloadedType.columns_hash['overloaded_string_with_limit'].limit
+      assert_equal 50, OverloadedType.type_for_attribute('overloaded_string_with_limit').limit
+      assert_equal 255, UnoverloadedType.type_for_attribute('overloaded_string_with_limit').limit
     end
 
     test "nonexistent attribute" do
@@ -87,29 +87,90 @@ module ActiveRecord
       assert_equal 4.4, data.overloaded_float
     end
 
-    test "overloading properties does not change column order" do
-      column_names = OverloadedType.column_names
-      assert_equal %w(id overloaded_float unoverloaded_float overloaded_string_with_limit string_with_default non_existent_decimal), column_names
+    test "overloading properties does not attribute method order" do
+      attribute_names = OverloadedType.attribute_names
+      assert_equal %w(id overloaded_float unoverloaded_float overloaded_string_with_limit string_with_default non_existent_decimal), attribute_names
     end
 
     test "caches are cleared" do
       klass = Class.new(OverloadedType)
 
-      assert_equal 6, klass.columns.length
-      assert_not klass.columns_hash.key?('wibble')
-      assert_equal 6, klass.column_types.length
+      assert_equal 6, klass.attribute_types.length
       assert_equal 6, klass.column_defaults.length
-      assert_not klass.column_names.include?('wibble')
-      assert_equal 5, klass.content_columns.length
+      assert_not klass.attribute_types.include?('wibble')
 
       klass.attribute :wibble, Type::Value.new
 
-      assert_equal 7, klass.columns.length
-      assert klass.columns_hash.key?('wibble')
-      assert_equal 7, klass.column_types.length
+      assert_equal 7, klass.attribute_types.length
       assert_equal 7, klass.column_defaults.length
-      assert klass.column_names.include?('wibble')
-      assert_equal 6, klass.content_columns.length
+      assert klass.attribute_types.include?('wibble')
+    end
+
+    test "the given default value is cast from user" do
+      custom_type = Class.new(Type::Value) do
+        def cast(*)
+          "from user"
+        end
+
+        def deserialize(*)
+          "from database"
+        end
+      end
+
+      klass = Class.new(OverloadedType) do
+        attribute :wibble, custom_type.new, default: "default"
+      end
+      model = klass.new
+
+      assert_equal "from user", model.wibble
+    end
+
+    test "procs for default values" do
+      klass = Class.new(OverloadedType) do
+        @@counter = 0
+        attribute :counter, :integer, default: -> { @@counter += 1 }
+      end
+
+      assert_equal 1, klass.new.counter
+      assert_equal 2, klass.new.counter
+    end
+
+    test "user provided defaults are persisted even if unchanged" do
+      model = OverloadedType.create!
+
+      assert_equal "the overloaded default", model.reload.string_with_default
+    end
+
+    if current_adapter?(:PostgreSQLAdapter)
+      test "array types can be specified" do
+        klass = Class.new(OverloadedType) do
+          attribute :my_array, :string, limit: 50, array: true
+          attribute :my_int_array, :integer, array: true
+        end
+
+        string_array = ConnectionAdapters::PostgreSQL::OID::Array.new(
+          Type::String.new(limit: 50))
+        int_array = ConnectionAdapters::PostgreSQL::OID::Array.new(
+          Type::Integer.new)
+        assert_not_equal string_array, int_array
+        assert_equal string_array, klass.type_for_attribute("my_array")
+        assert_equal int_array, klass.type_for_attribute("my_int_array")
+      end
+
+      test "range types can be specified" do
+        klass = Class.new(OverloadedType) do
+          attribute :my_range, :string, limit: 50, range: true
+          attribute :my_int_range, :integer, range: true
+        end
+
+        string_range = ConnectionAdapters::PostgreSQL::OID::Range.new(
+          Type::String.new(limit: 50))
+        int_range = ConnectionAdapters::PostgreSQL::OID::Range.new(
+          Type::Integer.new)
+        assert_not_equal string_range, int_range
+        assert_equal string_range, klass.type_for_attribute("my_range")
+        assert_equal int_range, klass.type_for_attribute("my_int_range")
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/autosave_association_test.rb b/activerecord/test/cases/autosave_association_test.rb
index 52765881d0..0df8f1f798 100644
--- a/activerecord/test/cases/autosave_association_test.rb
+++ b/activerecord/test/cases/autosave_association_test.rb
@@ -24,6 +24,8 @@ require 'models/molecule'
 require 'models/member'
 require 'models/member_detail'
 require 'models/organization'
+require 'models/guitar'
+require 'models/tuning_peg'
 
 class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
   def test_autosave_validation
@@ -43,7 +45,7 @@ class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
     reference = Class.new(ActiveRecord::Base) {
       self.table_name = "references"
       def self.name; 'Reference'; end
-      belongs_to :person, autosave: true, class: person
+      belongs_to :person, autosave: true, anonymous_class: person
     }
 
     u = person.create!(first_name: 'cool')
@@ -67,6 +69,14 @@ class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
     assert_no_difference_when_adding_callbacks_twice_for Pirate, :parrots
   end
 
+  def test_cyclic_autosaves_do_not_add_multiple_validations
+    ship = ShipWithoutNestedAttributes.new
+    ship.prisoners.build
+
+    assert_not ship.valid?
+    assert_equal 1, ship.errors[:name].length
+  end
+
   private
 
   def assert_no_difference_when_adding_callbacks_twice_for(model, association_name)
@@ -149,7 +159,8 @@ class TestDefaultAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCas
     assert_equal a, firm.account
     assert firm.save
     assert_equal a, firm.account
-    assert_equal a, firm.account(true)
+    firm.association(:account).reload
+    assert_equal a, firm.account
   end
 
   def test_assignment_before_either_saved
@@ -162,7 +173,8 @@ class TestDefaultAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCas
     assert firm.persisted?
     assert a.persisted?
     assert_equal a, firm.account
-    assert_equal a, firm.account(true)
+    firm.association(:account).reload
+    assert_equal a, firm.account
   end
 
   def test_not_resaved_when_unchanged
@@ -248,7 +260,8 @@ class TestDefaultAutosaveAssociationOnABelongsToAssociation < ActiveRecord::Test
     assert apple.save
     assert apple.persisted?
     assert_equal apple, client.firm
-    assert_equal apple, client.firm(true)
+    client.association(:firm).reload
+    assert_equal apple, client.firm
   end
 
   def test_assignment_before_either_saved
@@ -261,7 +274,8 @@ class TestDefaultAutosaveAssociationOnABelongsToAssociation < ActiveRecord::Test
     assert final_cut.persisted?
     assert apple.persisted?
     assert_equal apple, final_cut.firm
-    assert_equal apple, final_cut.firm(true)
+    final_cut.association(:firm).reload
+    assert_equal apple, final_cut.firm
   end
 
   def test_store_two_association_with_one_save
@@ -385,6 +399,40 @@ class TestDefaultAutosaveAssociationOnAHasManyAssociationWithAcceptsNestedAttrib
     assert_not molecule.persisted?, 'Molecule should not be persisted when its electrons are invalid'
   end
 
+  def test_errors_should_be_indexed_when_passed_as_array
+    guitar = Guitar.new
+    tuning_peg_valid = TuningPeg.new
+    tuning_peg_valid.pitch = 440.0
+    tuning_peg_invalid = TuningPeg.new
+
+    guitar.tuning_pegs = [tuning_peg_valid, tuning_peg_invalid]
+
+    assert_not tuning_peg_invalid.valid?
+    assert tuning_peg_valid.valid?
+    assert_not guitar.valid?
+    assert_equal ["is not a number"], guitar.errors["tuning_pegs[1].pitch"]
+    assert_not_equal ["is not a number"], guitar.errors["tuning_pegs.pitch"]
+  end
+
+  def test_errors_should_be_indexed_when_global_flag_is_set
+    old_attribute_config = ActiveRecord::Base.index_nested_attribute_errors
+    ActiveRecord::Base.index_nested_attribute_errors = true
+
+    molecule = Molecule.new
+    valid_electron = Electron.new(name: 'electron')
+    invalid_electron = Electron.new
+
+    molecule.electrons = [valid_electron, invalid_electron]
+
+    assert_not invalid_electron.valid?
+    assert valid_electron.valid?
+    assert_not molecule.valid?
+    assert_equal ["can't be blank"], molecule.errors["electrons[1].name"]
+    assert_not_equal ["can't be blank"], molecule.errors["electrons.name"]
+  ensure
+    ActiveRecord::Base.index_nested_attribute_errors = old_attribute_config
+  end
+
   def test_valid_adding_with_nested_attributes
     molecule = Molecule.new
     valid_electron = Electron.new(name: 'electron')
@@ -456,7 +504,7 @@ class TestDefaultAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCa
     assert_equal new_client, companies(:first_firm).clients_of_firm.last
     assert !companies(:first_firm).save
     assert !new_client.persisted?
-    assert_equal 2, companies(:first_firm).clients_of_firm(true).size
+    assert_equal 2, companies(:first_firm).clients_of_firm.reload.size
   end
 
   def test_adding_before_save
@@ -481,7 +529,7 @@ class TestDefaultAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCa
     assert_equal no_of_clients + 2, Client.count  # Clients were saved to database.
 
     assert_equal 2, new_firm.clients_of_firm.size
-    assert_equal 2, new_firm.clients_of_firm(true).size
+    assert_equal 2, new_firm.clients_of_firm.reload.size
   end
 
   def test_assign_ids
@@ -510,7 +558,7 @@ class TestDefaultAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCa
     company.name += '-changed'
     assert_queries(2) { assert company.save }
     assert new_client.persisted?
-    assert_equal 3, company.clients_of_firm(true).size
+    assert_equal 3, company.clients_of_firm.reload.size
   end
 
   def test_build_many_before_save
@@ -519,7 +567,7 @@ class TestDefaultAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCa
 
     company.name += '-changed'
     assert_queries(3) { assert company.save }
-    assert_equal 4, company.clients_of_firm(true).size
+    assert_equal 4, company.clients_of_firm.reload.size
   end
 
   def test_build_via_block_before_save
@@ -530,7 +578,7 @@ class TestDefaultAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCa
     company.name += '-changed'
     assert_queries(2) { assert company.save }
     assert new_client.persisted?
-    assert_equal 3, company.clients_of_firm(true).size
+    assert_equal 3, company.clients_of_firm.reload.size
   end
 
   def test_build_many_via_block_before_save
@@ -543,7 +591,7 @@ class TestDefaultAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCa
 
     company.name += '-changed'
     assert_queries(3) { assert company.save }
-    assert_equal 4, company.clients_of_firm(true).size
+    assert_equal 4, company.clients_of_firm.reload.size
   end
 
   def test_replace_on_new_object
@@ -629,7 +677,7 @@ class TestDefaultAutosaveAssociationOnNewRecord < ActiveRecord::TestCase
 end
 
 class TestDestroyAsPartOfAutosaveAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   setup do
     @pirate = Pirate.create(:catchphrase => "Don' botharrr talkin' like one, savvy?")
@@ -637,7 +685,7 @@ class TestDestroyAsPartOfAutosaveAssociation < ActiveRecord::TestCase
   end
 
   teardown do
-    # We are running without transactional fixtures and need to cleanup.
+    # We are running without transactional tests and need to cleanup.
     Bird.delete_all
     Parrot.delete_all
     @ship.delete
@@ -1009,7 +1057,7 @@ class TestDestroyAsPartOfAutosaveAssociation < ActiveRecord::TestCase
 end
 
 class TestAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1061,11 +1109,16 @@ class TestAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCase
   end
 
   def test_should_not_ignore_different_error_messages_on_the_same_attribute
+    old_validators = Ship._validators.deep_dup
+    old_callbacks = Ship._validate_callbacks.deep_dup
     Ship.validates_format_of :name, :with => /\w/
     @pirate.ship.name   = ""
     @pirate.catchphrase = nil
     assert @pirate.invalid?
     assert_equal ["can't be blank", "is invalid"], @pirate.errors[:"ship.name"]
+  ensure
+    Ship._validators = old_validators if old_validators
+    Ship._validate_callbacks = old_callbacks if old_callbacks
   end
 
   def test_should_still_allow_to_bypass_validations_on_the_associated_model
@@ -1137,10 +1190,17 @@ class TestAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCase
   def test_should_not_load_the_associated_model
     assert_queries(1) { @pirate.catchphrase = 'Arr'; @pirate.save! }
   end
+
+  def test_mark_for_destruction_is_ignored_without_autosave_true
+    ship = ShipWithoutNestedAttributes.new(name: "The Black Flag")
+    ship.parts.build.mark_for_destruction
+
+    assert_not ship.valid?
+  end
 end
 
 class TestAutosaveAssociationOnAHasOneThroughAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1161,7 +1221,7 @@ class TestAutosaveAssociationOnAHasOneThroughAssociation < ActiveRecord::TestCas
 end
 
 class TestAutosaveAssociationOnABelongsToAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1273,6 +1333,16 @@ module AutosaveAssociationOnACollectionAssociationTests
     assert_equal new_names, @pirate.reload.send(@association_name).map(&:name)
   end
 
+  def test_should_update_children_when_autosave_is_true_and_parent_is_new_but_child_is_not
+    parrot = Parrot.create!(name: "Polly")
+    parrot.name = "Squawky"
+    pirate = Pirate.new(parrots: [parrot], catchphrase: "Arrrr")
+
+    pirate.save!
+
+    assert_equal "Squawky", parrot.reload.name
+  end
+
   def test_should_automatically_validate_the_associated_models
     @pirate.send(@association_name).each { |child| child.name = '' }
 
@@ -1409,7 +1479,7 @@ module AutosaveAssociationOnACollectionAssociationTests
 end
 
 class TestAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1425,7 +1495,7 @@ class TestAutosaveAssociationOnAHasManyAssociation < ActiveRecord::TestCase
 end
 
 class TestAutosaveAssociationOnAHasAndBelongsToManyAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1442,7 +1512,7 @@ class TestAutosaveAssociationOnAHasAndBelongsToManyAssociation < ActiveRecord::T
 end
 
 class TestAutosaveAssociationOnAHasAndBelongsToManyAssociationWithAcceptsNestedAttributes < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1459,7 +1529,7 @@ class TestAutosaveAssociationOnAHasAndBelongsToManyAssociationWithAcceptsNestedA
 end
 
 class TestAutosaveAssociationValidationsOnAHasManyAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1476,7 +1546,7 @@ class TestAutosaveAssociationValidationsOnAHasManyAssociation < ActiveRecord::Te
 end
 
 class TestAutosaveAssociationValidationsOnAHasOneAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1499,7 +1569,7 @@ class TestAutosaveAssociationValidationsOnAHasOneAssociation < ActiveRecord::Tes
 end
 
 class TestAutosaveAssociationValidationsOnABelongsToAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1520,7 +1590,7 @@ class TestAutosaveAssociationValidationsOnABelongsToAssociation < ActiveRecord::
 end
 
 class TestAutosaveAssociationValidationsOnAHABTMAssociation < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
@@ -1543,7 +1613,7 @@ class TestAutosaveAssociationValidationsOnAHABTMAssociation < ActiveRecord::Test
 end
 
 class TestAutosaveAssociationValidationMethodsGeneration < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     super
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 0debd30e5c..dbbcaa075d 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1,7 +1,4 @@
-# encoding: utf-8
-
 require "cases/helper"
-require 'active_support/concurrency/latch'
 require 'models/post'
 require 'models/author'
 require 'models/topic'
@@ -29,6 +26,7 @@ require 'models/bird'
 require 'models/car'
 require 'models/bulb'
 require 'rexml/document'
+require 'concurrent/atomics'
 
 class FirstAbstractClass < ActiveRecord::Base
   self.abstract_class = true
@@ -206,7 +204,7 @@ class BasicsTest < ActiveRecord::TestCase
     )
 
     # For adapters which support microsecond resolution.
-    if current_adapter?(:PostgreSQLAdapter, :SQLite3Adapter) || mysql_56?
+    if subsecond_precision_supported?
       assert_equal 11, Topic.find(1).written_on.sec
       assert_equal 223300, Topic.find(1).written_on.usec
       assert_equal 9900, Topic.find(2).written_on.usec
@@ -813,7 +811,6 @@ class BasicsTest < ActiveRecord::TestCase
   def test_dup_does_not_copy_associations
     author = authors(:david)
     assert_not_equal [], author.posts
-    author.send(:clear_association_cache)
 
     author_dup = author.dup
     assert_equal [], author_dup.posts
@@ -904,8 +901,8 @@ class BasicsTest < ActiveRecord::TestCase
   class NumericData < ActiveRecord::Base
     self.table_name = 'numeric_data'
 
-    attribute :my_house_population, Type::Integer.new
-    attribute :atoms_in_universe, Type::Integer.new
+    attribute :my_house_population, :integer
+    attribute :atoms_in_universe, :integer
   end
 
   def test_big_decimal_conditions
@@ -947,6 +944,34 @@ class BasicsTest < ActiveRecord::TestCase
     assert_equal BigDecimal("1000234000567.95"), m1.big_bank_balance
   end
 
+  def test_numeric_fields_with_scale
+    m = NumericData.new(
+      :bank_balance => 1586.43122334,
+      :big_bank_balance => BigDecimal("234000567.952344"),
+      :world_population => 6000000000,
+      :my_house_population => 3
+    )
+    assert m.save
+
+    m1 = NumericData.find(m.id)
+    assert_not_nil m1
+
+    # As with migration_test.rb, we should make world_population >= 2**62
+    # to cover 64-bit platforms and test it is a Bignum, but the main thing
+    # is that it's an Integer.
+    assert_kind_of Integer, m1.world_population
+    assert_equal 6000000000, m1.world_population
+
+    assert_kind_of Fixnum, m1.my_house_population
+    assert_equal 3, m1.my_house_population
+
+    assert_kind_of BigDecimal, m1.bank_balance
+    assert_equal BigDecimal("1586.43"), m1.bank_balance
+
+    assert_kind_of BigDecimal, m1.big_bank_balance
+    assert_equal BigDecimal("234000567.95"), m1.big_bank_balance
+  end
+
   def test_auto_id
     auto = AutoId.new
     auto.save
@@ -1010,54 +1035,61 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_switching_between_table_name
+    k = Class.new(Joke)
+
     assert_difference("GoodJoke.count") do
-      Joke.table_name = "cold_jokes"
-      Joke.create
+      k.table_name = "cold_jokes"
+      k.create
 
-      Joke.table_name = "funny_jokes"
-      Joke.create
+      k.table_name = "funny_jokes"
+      k.create
     end
   end
 
   def test_clear_cash_when_setting_table_name
-    Joke.table_name = "cold_jokes"
-    before_columns = Joke.columns
-    before_seq     = Joke.sequence_name
+    original_table_name = Joke.table_name
 
     Joke.table_name = "funny_jokes"
+    before_columns = Joke.columns
+    before_seq = Joke.sequence_name
+
+    Joke.table_name = "cold_jokes"
     after_columns = Joke.columns
-    after_seq     = Joke.sequence_name
+    after_seq = Joke.sequence_name
 
     assert_not_equal before_columns, after_columns
     assert_not_equal before_seq, after_seq unless before_seq.nil? && after_seq.nil?
+  ensure
+    Joke.table_name = original_table_name
   end
 
   def test_dont_clear_sequence_name_when_setting_explicitly
-    Joke.sequence_name = "black_jokes_seq"
-    Joke.table_name    = "cold_jokes"
-    before_seq         = Joke.sequence_name
+    k = Class.new(Joke)
+    k.sequence_name = "black_jokes_seq"
+    k.table_name = "cold_jokes"
+    before_seq = k.sequence_name
 
-    Joke.table_name    = "funny_jokes"
-    after_seq          = Joke.sequence_name
+    k.table_name = "funny_jokes"
+    after_seq = k.sequence_name
 
     assert_equal before_seq, after_seq unless before_seq.nil? && after_seq.nil?
-  ensure
-    Joke.reset_sequence_name
   end
 
   def test_dont_clear_inheritance_column_when_setting_explicitly
-    Joke.inheritance_column = "my_type"
-    before_inherit = Joke.inheritance_column
+    k = Class.new(Joke)
+    k.inheritance_column = "my_type"
+    before_inherit = k.inheritance_column
 
-    Joke.reset_column_information
-    after_inherit = Joke.inheritance_column
+    k.reset_column_information
+    after_inherit = k.inheritance_column
 
     assert_equal before_inherit, after_inherit unless before_inherit.blank? && after_inherit.blank?
   end
 
   def test_set_table_name_symbol_converted_to_string
-    Joke.table_name = :cold_jokes
-    assert_equal 'cold_jokes', Joke.table_name
+    k = Class.new(Joke)
+    k.table_name = :cold_jokes
+    assert_equal 'cold_jokes', k.table_name
   end
 
   def test_quoted_table_name_after_set_table_name
@@ -1265,9 +1297,10 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_compute_type_no_method_error
-    ActiveSupport::Dependencies.stubs(:safe_constantize).raises(NoMethodError)
-    assert_raises NoMethodError do
-      ActiveRecord::Base.send :compute_type, 'InvalidModel'
+    ActiveSupport::Dependencies.stub(:safe_constantize, proc{ raise NoMethodError }) do
+      assert_raises NoMethodError do
+        ActiveRecord::Base.send :compute_type, 'InvalidModel'
+      end
     end
   end
 
@@ -1281,18 +1314,20 @@ class BasicsTest < ActiveRecord::TestCase
       error = e
     end
 
-    ActiveSupport::Dependencies.stubs(:safe_constantize).raises(e)
+    ActiveSupport::Dependencies.stub(:safe_constantize, proc{ raise e }) do
 
-    exception = assert_raises NameError do
-      ActiveRecord::Base.send :compute_type, 'InvalidModel'
+      exception = assert_raises NameError do
+        ActiveRecord::Base.send :compute_type, 'InvalidModel'
+      end
+      assert_equal error.message, exception.message
     end
-    assert_equal error.message, exception.message
   end
 
   def test_compute_type_argument_error
-    ActiveSupport::Dependencies.stubs(:safe_constantize).raises(ArgumentError)
-    assert_raises ArgumentError do
-      ActiveRecord::Base.send :compute_type, 'InvalidModel'
+    ActiveSupport::Dependencies.stub(:safe_constantize, proc{ raise ArgumentError }) do
+      assert_raises ArgumentError do
+        ActiveRecord::Base.send :compute_type, 'InvalidModel'
+      end
     end
   end
 
@@ -1405,15 +1440,13 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_uniq_delegates_to_scoped
-    scope = stub
-    Bird.stubs(:all).returns(mock(:uniq => scope))
-    assert_equal scope, Bird.uniq
+    assert_deprecated do
+      assert_equal Bird.all.distinct, Bird.uniq
+    end
   end
 
   def test_distinct_delegates_to_scoped
-    scope = stub
-    Bird.stubs(:all).returns(mock(:distinct => scope))
-    assert_equal scope, Bird.distinct
+    assert_equal Bird.all.distinct, Bird.distinct
   end
 
   def test_table_name_with_2_abstract_subclasses
@@ -1428,7 +1461,7 @@ class BasicsTest < ActiveRecord::TestCase
     attrs.delete 'id'
 
     typecast = Class.new(ActiveRecord::Type::Value) {
-      def type_cast value
+      def cast value
         "t.lo"
       end
     }
@@ -1502,20 +1535,20 @@ class BasicsTest < ActiveRecord::TestCase
     orig_handler = klass.connection_handler
     new_handler = ActiveRecord::ConnectionAdapters::ConnectionHandler.new
     after_handler = nil
-    latch1 = ActiveSupport::Concurrency::Latch.new
-    latch2 = ActiveSupport::Concurrency::Latch.new
+    latch1 = Concurrent::CountDownLatch.new
+    latch2 = Concurrent::CountDownLatch.new
 
     t = Thread.new do
       klass.connection_handler = new_handler
-      latch1.release
-      latch2.await
+      latch1.count_down
+      latch2.wait
       after_handler = klass.connection_handler
     end
 
-    latch1.await
+    latch1.wait
 
     klass.connection_handler = orig_handler
-    latch2.release
+    latch2.count_down
     t.join
 
     assert_equal after_handler, new_handler
@@ -1538,4 +1571,22 @@ class BasicsTest < ActiveRecord::TestCase
 
     assert_not topic.id_changed?
   end
+
+  test "ignored columns are not present in columns_hash" do
+    cache_columns = Developer.connection.schema_cache.columns_hash(Developer.table_name)
+    assert_includes cache_columns.keys, 'first_name'
+    refute_includes Developer.columns_hash.keys, 'first_name'
+  end
+
+  test "ignored columns have no attribute methods" do
+    refute Developer.new.respond_to?(:first_name)
+    refute Developer.new.respond_to?(:first_name=)
+    refute Developer.new.respond_to?(:first_name?)
+  end
+
+  test "ignored columns don't prevent explicit declaration of attribute methods" do
+    assert Developer.new.respond_to?(:last_name)
+    assert Developer.new.respond_to?(:last_name=)
+    assert Developer.new.respond_to?(:last_name?)
+  end
 end
diff --git a/activerecord/test/cases/batches_test.rb b/activerecord/test/cases/batches_test.rb
index c12fa03015..9cb70ee239 100644
--- a/activerecord/test/cases/batches_test.rb
+++ b/activerecord/test/cases/batches_test.rb
@@ -37,9 +37,9 @@ class EachTest < ActiveRecord::TestCase
 
   if Enumerator.method_defined? :size
     def test_each_should_return_a_sized_enumerator
-      assert_equal 11, Post.find_each(:batch_size => 1).size
-      assert_equal 5, Post.find_each(:batch_size => 2, :start => 7).size
-      assert_equal 11, Post.find_each(:batch_size => 10_000).size
+      assert_equal 11, Post.find_each(batch_size: 1).size
+      assert_equal 5, Post.find_each(batch_size:  2, begin_at: 7).size
+      assert_equal 11, Post.find_each(batch_size: 10_000).size
     end
   end
 
@@ -53,7 +53,7 @@ class EachTest < ActiveRecord::TestCase
   end
 
   def test_each_should_raise_if_select_is_set_without_id
-    assert_raise(RuntimeError) do
+    assert_raise(ArgumentError) do
       Post.select(:title).find_each(batch_size: 1) { |post|
         flunk "should not call this block"
       }
@@ -69,13 +69,15 @@ class EachTest < ActiveRecord::TestCase
   end
 
   def test_warn_if_limit_scope_is_set
-    ActiveRecord::Base.logger.expects(:warn)
-    Post.limit(1).find_each { |post| post }
+    assert_called(ActiveRecord::Base.logger, :warn) do
+      Post.limit(1).find_each { |post| post }
+    end
   end
 
   def test_warn_if_order_scope_is_set
-    ActiveRecord::Base.logger.expects(:warn)
-    Post.order("title").find_each { |post| post }
+    assert_called(ActiveRecord::Base.logger, :warn) do
+      Post.order("title").find_each { |post| post }
+    end
   end
 
   def test_logger_not_required
@@ -99,7 +101,16 @@ class EachTest < ActiveRecord::TestCase
 
   def test_find_in_batches_should_start_from_the_start_option
     assert_queries(@total) do
-      Post.find_in_batches(:batch_size => 1, :start => 2) do |batch|
+      Post.find_in_batches(batch_size: 1, begin_at: 2) do |batch|
+        assert_kind_of Array, batch
+        assert_kind_of Post, batch.first
+      end
+    end
+  end
+
+  def test_find_in_batches_should_end_at_the_end_option
+    assert_queries(6) do
+      Post.find_in_batches(batch_size: 1, end_at: 5) do |batch|
         assert_kind_of Array, batch
         assert_kind_of Post, batch.first
       end
@@ -128,14 +139,15 @@ class EachTest < ActiveRecord::TestCase
 
   def test_find_in_batches_should_not_use_records_after_yielding_them_in_case_original_array_is_modified
     not_a_post = "not a post"
-    not_a_post.stubs(:id).raises(StandardError, "not_a_post had #id called on it")
+    def not_a_post.id; end
+    not_a_post.stub(:id, ->{ raise StandardError.new("not_a_post had #id called on it") }) do
+      assert_nothing_raised do
+        Post.find_in_batches(:batch_size => 1) do |batch|
+          assert_kind_of Array, batch
+          assert_kind_of Post, batch.first
 
-    assert_nothing_raised do
-      Post.find_in_batches(:batch_size => 1) do |batch|
-        assert_kind_of Array, batch
-        assert_kind_of Post, batch.first
-
-        batch.map! { not_a_post }
+          batch.map! { not_a_post }
+        end
       end
     end
   end
@@ -163,7 +175,7 @@ class EachTest < ActiveRecord::TestCase
 
   def test_find_in_batches_should_not_modify_passed_options
     assert_nothing_raised do
-      Post.find_in_batches({ batch_size: 42, start: 1 }.freeze){}
+      Post.find_in_batches({ batch_size: 42, begin_at: 1 }.freeze){}
     end
   end
 
@@ -172,7 +184,7 @@ class EachTest < ActiveRecord::TestCase
     start_nick = nick_order_subscribers.second.nick
 
     subscribers = []
-    Subscriber.find_in_batches(:batch_size => 1, :start => start_nick) do |batch|
+    Subscriber.find_in_batches(batch_size: 1, begin_at: start_nick) do |batch|
       subscribers.concat(batch)
     end
 
@@ -181,15 +193,16 @@ class EachTest < ActiveRecord::TestCase
 
   def test_find_in_batches_should_use_any_column_as_primary_key_when_start_is_not_specified
     assert_queries(Subscriber.count + 1) do
-      Subscriber.find_each(:batch_size => 1) do |subscriber|
-        assert_kind_of Subscriber, subscriber
+      Subscriber.find_in_batches(batch_size: 1) do |batch|
+        assert_kind_of Array, batch
+        assert_kind_of Subscriber, batch.first
       end
     end
   end
 
   def test_find_in_batches_should_return_an_enumerator
     enum = nil
-    assert_queries(0) do
+    assert_no_queries do
       enum = Post.find_in_batches(:batch_size => 1)
     end
     assert_queries(4) do
@@ -200,11 +213,260 @@ class EachTest < ActiveRecord::TestCase
     end
   end
 
+  def test_in_batches_should_not_execute_any_query
+    assert_no_queries do
+      assert_kind_of ActiveRecord::Batches::BatchEnumerator, Post.in_batches(of: 2)
+    end
+  end
+
+  def test_in_batches_should_yield_relation_if_block_given
+    assert_queries(6) do
+      Post.in_batches(of: 2) do |relation|
+        assert_kind_of ActiveRecord::Relation, relation
+      end
+    end
+  end
+
+  def test_in_batches_should_be_enumerable_if_no_block_given
+    assert_queries(6) do
+      Post.in_batches(of: 2).each do |relation|
+        assert_kind_of ActiveRecord::Relation, relation
+      end
+    end
+  end
+
+  def test_in_batches_each_record_should_yield_record_if_block_is_given
+    assert_queries(6) do
+      Post.in_batches(of: 2).each_record do |post|
+        assert post.title.present?
+        assert_kind_of Post, post
+      end
+    end
+  end
+
+  def test_in_batches_each_record_should_return_enumerator_if_no_block_given
+    assert_queries(6) do
+      Post.in_batches(of: 2).each_record.with_index do |post, i|
+        assert post.title.present?
+        assert_kind_of Post, post
+      end
+    end
+  end
+
+  def test_in_batches_each_record_should_be_ordered_by_id
+    ids = Post.order('id ASC').pluck(:id)
+    assert_queries(6) do
+      Post.in_batches(of: 2).each_record.with_index do |post, i|
+        assert_equal ids[i], post.id
+      end
+    end
+  end
+
+  def test_in_batches_update_all_affect_all_records
+    assert_queries(6 + 6) do # 6 selects, 6 updates
+      Post.in_batches(of: 2).update_all(title: "updated-title")
+    end
+    assert_equal Post.all.pluck(:title), ["updated-title"] * Post.count
+  end
+
+  def test_in_batches_delete_all_should_not_delete_records_in_other_batches
+    not_deleted_count = Post.where('id <= 2').count
+    Post.where('id > 2').in_batches(of: 2).delete_all
+    assert_equal 0, Post.where('id > 2').count
+    assert_equal not_deleted_count, Post.count
+  end
+
+  def test_in_batches_should_not_be_loaded
+    Post.in_batches(of: 1) do |relation|
+      assert_not relation.loaded?
+    end
+
+    Post.in_batches(of: 1, load: false) do |relation|
+      assert_not relation.loaded?
+    end
+  end
+
+  def test_in_batches_should_be_loaded
+    Post.in_batches(of: 1, load: true) do |relation|
+      assert relation.loaded?
+    end
+  end
+
+  def test_in_batches_if_not_loaded_executes_more_queries
+    assert_queries(@total + 1) do
+      Post.in_batches(of: 1, load: false) do |relation|
+        assert_not relation.loaded?
+      end
+    end
+  end
+
+  def test_in_batches_should_return_relations
+    assert_queries(@total + 1) do
+      Post.in_batches(of: 1) do |relation|
+        assert_kind_of ActiveRecord::Relation, relation
+      end
+    end
+  end
+
+  def test_in_batches_should_start_from_the_start_option
+    post = Post.order('id ASC').where('id >= ?', 2).first
+    assert_queries(2) do
+      relation = Post.in_batches(of: 1, begin_at: 2).first
+      assert_equal post, relation.first
+    end
+  end
+
+  def test_in_batches_should_end_at_the_end_option
+    post = Post.order('id DESC').where('id <= ?', 5).first
+    assert_queries(7) do
+      relation = Post.in_batches(of: 1, end_at: 5, load: true).reverse_each.first
+      assert_equal post, relation.last
+    end
+  end
+
+  def test_in_batches_shouldnt_execute_query_unless_needed
+    assert_queries(2) do
+      Post.in_batches(of: @total) { |relation| assert_kind_of ActiveRecord::Relation, relation }
+    end
+
+    assert_queries(1) do
+      Post.in_batches(of: @total + 1) { |relation| assert_kind_of ActiveRecord::Relation, relation }
+    end
+  end
+
+  def test_in_batches_should_quote_batch_order
+    c = Post.connection
+    assert_sql(/ORDER BY #{c.quote_table_name('posts')}.#{c.quote_column_name('id')}/) do
+      Post.in_batches(of: 1) do |relation|
+        assert_kind_of ActiveRecord::Relation, relation
+        assert_kind_of Post, relation.first
+      end
+    end
+  end
+
+  def test_in_batches_should_not_use_records_after_yielding_them_in_case_original_array_is_modified
+    not_a_post = "not a post"
+    def not_a_post.id
+      raise StandardError.new("not_a_post had #id called on it")
+    end
+
+    assert_nothing_raised do
+      Post.in_batches(of: 1) do |relation|
+        assert_kind_of ActiveRecord::Relation, relation
+        assert_kind_of Post, relation.first
+
+        relation = [not_a_post] * relation.count
+      end
+    end
+  end
+
+  def test_in_batches_should_not_ignore_default_scope_without_order_statements
+    special_posts_ids = SpecialPostWithDefaultScope.all.map(&:id).sort
+    posts = []
+    SpecialPostWithDefaultScope.in_batches do |relation|
+      posts.concat(relation)
+    end
+    assert_equal special_posts_ids, posts.map(&:id)
+  end
+
+  def test_in_batches_should_not_modify_passed_options
+    assert_nothing_raised do
+      Post.in_batches({ of: 42, begin_at: 1 }.freeze){}
+    end
+  end
+
+  def test_in_batches_should_use_any_column_as_primary_key
+    nick_order_subscribers = Subscriber.order('nick asc')
+    start_nick = nick_order_subscribers.second.nick
+
+    subscribers = []
+    Subscriber.in_batches(of: 1, begin_at: start_nick) do |relation|
+      subscribers.concat(relation)
+    end
+
+    assert_equal nick_order_subscribers[1..-1].map(&:id), subscribers.map(&:id)
+  end
+
+  def test_in_batches_should_use_any_column_as_primary_key_when_start_is_not_specified
+    assert_queries(Subscriber.count + 1) do
+      Subscriber.in_batches(of: 1, load: true) do |relation|
+        assert_kind_of ActiveRecord::Relation, relation
+        assert_kind_of Subscriber, relation.first
+      end
+    end
+  end
+
+  def test_in_batches_should_return_an_enumerator
+    enum = nil
+    assert_no_queries do
+      enum = Post.in_batches(of: 1)
+    end
+    assert_queries(4) do
+      enum.first(4) do |relation|
+        assert_kind_of ActiveRecord::Relation, relation
+        assert_kind_of Post, relation.first
+      end
+    end
+  end
+
+  def test_in_batches_relations_should_not_overlap_with_each_other
+    seen_posts = []
+    Post.in_batches(of: 2, load: true) do |relation|
+      relation.to_a.each do |post|
+        assert_not seen_posts.include?(post)
+        seen_posts << post
+      end
+    end
+  end
+
+  def test_in_batches_relations_with_condition_should_not_overlap_with_each_other
+    seen_posts = []
+    author_id = Post.first.author_id
+    posts_by_author = Post.where(author_id: author_id)
+    Post.in_batches(of: 2) do |batch|
+      seen_posts += batch.where(author_id: author_id)
+    end
+
+    assert_equal posts_by_author.pluck(:id).sort, seen_posts.map(&:id).sort
+  end
+
+  def test_in_batches_relations_update_all_should_not_affect_matching_records_in_other_batches
+    Post.update_all(author_id: 0)
+    person = Post.last
+    person.update_attributes(author_id: 1)
+
+    Post.in_batches(of: 2) do |batch|
+      batch.where('author_id >= 1').update_all('author_id = author_id + 1')
+    end
+    assert_equal 2, person.reload.author_id # incremented only once
+  end
+
+  def test_find_in_batches_start_deprecated
+    assert_deprecated do
+      assert_queries(@total) do
+        Post.find_in_batches(batch_size: 1, start: 2) do |batch|
+          assert_kind_of Array, batch
+          assert_kind_of Post, batch.first
+        end
+      end
+    end
+  end
+
+  def test_find_each_start_deprecated
+    assert_deprecated do
+      assert_queries(@total) do
+        Post.find_each(batch_size: 1, start: 2) do |post|
+          assert_kind_of Post, post
+        end
+      end
+    end
+  end
+
   if Enumerator.method_defined? :size
     def test_find_in_batches_should_return_a_sized_enumerator
       assert_equal 11, Post.find_in_batches(:batch_size => 1).size
       assert_equal 6, Post.find_in_batches(:batch_size => 2).size
-      assert_equal 4, Post.find_in_batches(:batch_size => 2, :start => 4).size
+      assert_equal 4, Post.find_in_batches(batch_size: 2, begin_at: 4).size
       assert_equal 4, Post.find_in_batches(:batch_size => 3).size
       assert_equal 1, Post.find_in_batches(:batch_size => 10_000).size
     end
diff --git a/activerecord/test/cases/binary_test.rb b/activerecord/test/cases/binary_test.rb
index ccf2be369d..86dee929bf 100644
--- a/activerecord/test/cases/binary_test.rb
+++ b/activerecord/test/cases/binary_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 
 # Without using prepared statements, it makes no sense to test
diff --git a/activerecord/test/cases/bind_parameter_test.rb b/activerecord/test/cases/bind_parameter_test.rb
index 66663b3e0e..1e38b97c4a 100644
--- a/activerecord/test/cases/bind_parameter_test.rb
+++ b/activerecord/test/cases/bind_parameter_test.rb
@@ -22,8 +22,8 @@ module ActiveRecord
     def setup
       super
       @connection = ActiveRecord::Base.connection
-      @subscriber   = LogListener.new
-      @pk         = Topic.columns_hash[Topic.primary_key]
+      @subscriber = LogListener.new
+      @pk = Topic.columns_hash[Topic.primary_key]
       @subscription = ActiveSupport::Notifications.subscribe('sql.active_record', @subscriber)
     end
 
@@ -40,7 +40,7 @@ module ActiveRecord
 
       def test_binds_are_logged
         sub   = @connection.substitute_at(@pk)
-        binds = [[@pk, 1]]
+        binds = [Relation::QueryAttribute.new("id", 1, Type::Value.new)]
         sql   = "select * from topics where id = #{sub.to_sql}"
 
         @connection.exec_query(sql, 'SQL', binds)
@@ -49,29 +49,17 @@ module ActiveRecord
         assert_equal binds, message[4][:binds]
       end
 
-      def test_binds_are_logged_after_type_cast
-        sub   = @connection.substitute_at(@pk)
-        binds = [[@pk, "3"]]
-        sql   = "select * from topics where id = #{sub.to_sql}"
-
-        @connection.exec_query(sql, 'SQL', binds)
-
-        message = @subscriber.calls.find { |args| args[4][:sql] == sql }
-        assert_equal [[@pk, 3]], message[4][:binds]
-      end
-
       def test_find_one_uses_binds
         Topic.find(1)
-        binds = [[@pk, 1]]
-        message = @subscriber.calls.find { |args| args[4][:binds] == binds }
+        message = @subscriber.calls.find { |args| args[4][:binds].any? { |attr| attr.value == 1 } }
         assert message, 'expected a message with binds'
       end
 
-      def test_logs_bind_vars
+      def test_logs_bind_vars_after_type_cast
         payload = {
           :name  => 'SQL',
           :sql   => 'select * from topics where id = ?',
-          :binds => [[@pk, 10]]
+          :binds => [Relation::QueryAttribute.new("id", "10", Type::Integer.new)]
         }
         event  = ActiveSupport::Notifications::Event.new(
           'foo',
diff --git a/activerecord/test/cases/cache_key_test.rb b/activerecord/test/cases/cache_key_test.rb
new file mode 100644
index 0000000000..bb2829b3c1
--- /dev/null
+++ b/activerecord/test/cases/cache_key_test.rb
@@ -0,0 +1,25 @@
+require "cases/helper"
+
+module ActiveRecord
+  class CacheKeyTest < ActiveRecord::TestCase
+    self.use_transactional_tests = false
+
+    class CacheMe < ActiveRecord::Base; end
+
+    setup do
+      @connection = ActiveRecord::Base.connection
+      @connection.create_table(:cache_mes) { |t| t.timestamps }
+    end
+
+    teardown do
+      @connection.drop_table :cache_mes, if_exists: true
+    end
+
+    test "test_cache_key_format_is_not_too_precise" do
+      record = CacheMe.create
+      key = record.cache_key
+
+      assert_equal key, record.reload.cache_key
+    end
+  end
+end
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index 299217214e..4a0e6f497f 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -11,13 +11,17 @@ require 'models/minivan'
 require 'models/speedometer'
 require 'models/ship_part'
 require 'models/treasure'
+require 'models/developer'
+require 'models/comment'
+require 'models/rating'
+require 'models/post'
 
 class NumericData < ActiveRecord::Base
   self.table_name = 'numeric_data'
 
-  attribute :world_population, Type::Integer.new
-  attribute :my_house_population, Type::Integer.new
-  attribute :atoms_in_universe, Type::Integer.new
+  attribute :world_population, :integer
+  attribute :my_house_population, :integer
+  attribute :atoms_in_universe, :integer
 end
 
 class CalculationsTest < ActiveRecord::TestCase
@@ -27,11 +31,20 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal 318, Account.sum(:credit_limit)
   end
 
+  def test_should_sum_arel_attribute
+    assert_equal 318, Account.sum(Account.arel_table[:credit_limit])
+  end
+
   def test_should_average_field
     value = Account.average(:credit_limit)
     assert_equal 53.0, value
   end
 
+  def test_should_average_arel_attribute
+    value = Account.average(Account.arel_table[:credit_limit])
+    assert_equal 53.0, value
+  end
+
   def test_should_resolve_aliased_attributes
     assert_equal 318, Account.sum(:available_credit)
   end
@@ -56,14 +69,26 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal 60, Account.maximum(:credit_limit)
   end
 
+  def test_should_get_maximum_of_arel_attribute
+    assert_equal 60, Account.maximum(Account.arel_table[:credit_limit])
+  end
+
   def test_should_get_maximum_of_field_with_include
     assert_equal 55, Account.where("companies.name != 'Summit'").references(:companies).includes(:firm).maximum(:credit_limit)
   end
 
+  def test_should_get_maximum_of_arel_attribute_with_include
+    assert_equal 55, Account.where("companies.name != 'Summit'").references(:companies).includes(:firm).maximum(Account.arel_table[:credit_limit])
+  end
+
   def test_should_get_minimum_of_field
     assert_equal 50, Account.minimum(:credit_limit)
   end
 
+  def test_should_get_minimum_of_arel_attribute
+    assert_equal 50, Account.minimum(Account.arel_table[:credit_limit])
+  end
+
   def test_should_group_by_field
     c = Account.group(:firm_id).sum(:credit_limit)
     [1,6,2].each do |firm_id|
@@ -98,6 +123,25 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal 60,   c[2]
   end
 
+  def test_should_generate_valid_sql_with_joins_and_group
+    assert_nothing_raised ActiveRecord::StatementInvalid do
+      AuditLog.joins(:developer).group(:id).count
+    end
+  end
+
+  def test_should_calculate_against_given_relation
+    developer = Developer.create!(name: "developer")
+    developer.audit_logs.create!(message: "first log")
+    developer.audit_logs.create!(message: "second log")
+
+    c = developer.audit_logs.joins(:developer).group(:id).count
+
+    assert_equal developer.audit_logs.count, c.size
+    developer.audit_logs.each do |log|
+      assert_equal 1, c[log.id]
+    end
+  end
+
   def test_should_order_by_grouped_field
     c = Account.group(:firm_id).order("firm_id").sum(:credit_limit)
     assert_equal [1, 2, 6, 9], c.keys.compact
@@ -127,6 +171,14 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal 3, accounts.select(:firm_id).count
   end
 
+  def test_limit_should_apply_before_count_arel_attribute
+    accounts = Account.limit(3).where('firm_id IS NOT NULL')
+
+    firm_id_attribute = Account.arel_table[:firm_id]
+    assert_equal 3, accounts.count(firm_id_attribute)
+    assert_equal 3, accounts.select(firm_id_attribute).count
+  end
+
   def test_count_should_shortcut_with_limit_zero
     accounts = Account.limit(0)
 
@@ -349,13 +401,29 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal 6, Account.select("DISTINCT accounts.id").includes(:firm).count
   end
 
+  def test_count_selected_arel_attribute
+    assert_equal 5, Account.select(Account.arel_table[:firm_id]).count
+    assert_equal 4, Account.distinct.select(Account.arel_table[:firm_id]).count
+  end
+
   def test_count_with_column_parameter
     assert_equal 5, Account.count(:firm_id)
   end
 
+  def test_count_with_arel_attribute
+    assert_equal 5, Account.count(Account.arel_table[:firm_id])
+  end
+
+  def test_count_with_arel_star
+    assert_equal 6, Account.count(Arel.star)
+  end
+
   def test_count_with_distinct
     assert_equal 4, Account.select(:credit_limit).distinct.count
-    assert_equal 4, Account.select(:credit_limit).uniq.count
+
+    assert_deprecated do
+      assert_equal 4, Account.select(:credit_limit).uniq.count
+    end
   end
 
   def test_count_with_aliased_attribute
@@ -371,12 +439,27 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal 4, Account.joins(:firm).distinct.count('companies.id')
   end
 
+  def test_count_arel_attribute_in_joined_table_with
+    assert_equal 5, Account.joins(:firm).count(Company.arel_table[:id])
+    assert_equal 4, Account.joins(:firm).distinct.count(Company.arel_table[:id])
+  end
+
+  def test_count_selected_arel_attribute_in_joined_table
+    assert_equal 5, Account.joins(:firm).select(Company.arel_table[:id]).count
+    assert_equal 4, Account.joins(:firm).distinct.select(Company.arel_table[:id]).count
+  end
+
   def test_should_count_field_in_joined_table_with_group_by
     c = Account.group('accounts.firm_id').joins(:firm).count('companies.id')
 
     [1,6,2,9].each { |firm_id| assert c.keys.include?(firm_id) }
   end
 
+  def test_should_count_field_of_root_table_with_conflicting_group_by_column
+    assert_equal({ 1 => 1 }, Firm.joins(:accounts).group(:firm_id).count)
+    assert_equal({ 1 => 1 }, Firm.joins(:accounts).group('accounts.firm_id').count)
+  end
+
   def test_count_with_no_parameters_isnt_deprecated
     assert_not_deprecated { Account.count }
   end
@@ -500,8 +583,8 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal [ topic.written_on ], relation.pluck(:written_on)
   end
 
-  def test_pluck_and_uniq
-    assert_equal [50, 53, 55, 60], Account.order(:credit_limit).uniq.pluck(:credit_limit)
+  def test_pluck_and_distinct
+    assert_equal [50, 53, 55, 60], Account.order(:credit_limit).distinct.pluck(:credit_limit)
   end
 
   def test_pluck_in_relation
@@ -625,10 +708,85 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal [part.id], ShipPart.joins(:trinkets).pluck(:id)
   end
 
+  def test_pluck_loaded_relation
+    companies = Company.order(:id).limit(3).load
+    assert_no_queries do
+      assert_equal ['37signals', 'Summit', 'Microsoft'], companies.pluck(:name)
+    end
+  end
+
+  def test_pluck_loaded_relation_multiple_columns
+    companies = Company.order(:id).limit(3).load
+    assert_no_queries do
+      assert_equal [[1, '37signals'], [2, 'Summit'], [3, 'Microsoft']], companies.pluck(:id, :name)
+    end
+  end
+
+  def test_pluck_loaded_relation_sql_fragment
+    companies = Company.order(:name).limit(3).load
+    assert_queries 1 do
+      assert_equal ['37signals', 'Apex', 'Ex Nihilo'], companies.pluck('DISTINCT name')
+    end
+  end
+
   def test_grouped_calculation_with_polymorphic_relation
     part = ShipPart.create!(name: "has trinket")
     part.trinkets.create!
 
     assert_equal({ "has trinket" => part.id }, ShipPart.joins(:trinkets).group("ship_parts.name").sum(:id))
   end
+
+  def test_calculation_grouped_by_association_doesnt_error_when_no_records_have_association
+    Client.update_all(client_of: nil)
+    assert_equal({ nil => Client.count }, Client.group(:firm).count)
+  end
+
+  def test_should_reference_correct_aliases_while_joining_tables_of_has_many_through_association
+    assert_nothing_raised ActiveRecord::StatementInvalid do
+      developer = Developer.create!(name: 'developer')
+      developer.ratings.includes(comment: :post).where(posts: { id: 1 }).count
+    end
+  end
+
+  def test_sum_uses_enumerable_version_when_block_is_given
+    block_called = false
+    relation = Client.all.load
+
+    assert_no_queries do
+      assert_equal 0, relation.sum { block_called = true; 0 }
+    end
+    assert block_called
+  end
+
+  def test_having_with_strong_parameters
+    protected_params = Class.new do
+      attr_reader :permitted
+      alias :permitted? :permitted
+
+      def initialize(parameters)
+        @parameters = parameters
+        @permitted = false
+      end
+
+      def to_h
+        @parameters
+      end
+
+      def permit!
+        @permitted = true
+        self
+      end
+    end
+
+    params = protected_params.new(credit_limit: '50')
+
+    assert_raises(ActiveModel::ForbiddenAttributesError) do
+      Account.group(:id).having(params)
+    end
+
+    result = Account.group(:id).having(params.permit!)
+    assert_equal 50, result[0].credit_limit
+    assert_equal 50, result[1].credit_limit
+    assert_equal 50, result[2].credit_limit
+  end
 end
diff --git a/activerecord/test/cases/callbacks_test.rb b/activerecord/test/cases/callbacks_test.rb
index 670d94dc06..73ac30e547 100644
--- a/activerecord/test/cases/callbacks_test.rb
+++ b/activerecord/test/cases/callbacks_test.rb
@@ -288,7 +288,12 @@ class CallbacksTest < ActiveRecord::TestCase
       [ :after_save,                  :string ],
       [ :after_save,                  :proc   ],
       [ :after_save,                  :object ],
-      [ :after_save,                  :block  ]
+      [ :after_save,                  :block  ],
+      [ :after_commit,                :block  ],
+      [ :after_commit,                :object ],
+      [ :after_commit,                :proc   ],
+      [ :after_commit,                :string ],
+      [ :after_commit,                :method ]
     ], david.history
   end
 
@@ -357,7 +362,12 @@ class CallbacksTest < ActiveRecord::TestCase
       [ :after_save,                  :string ],
       [ :after_save,                  :proc   ],
       [ :after_save,                  :object ],
-      [ :after_save,                  :block  ]
+      [ :after_save,                  :block  ],
+      [ :after_commit,                :block  ],
+      [ :after_commit,                :object ],
+      [ :after_commit,                :proc   ],
+      [ :after_commit,                :string ],
+      [ :after_commit,                :method ]
     ], david.history
   end
 
@@ -408,7 +418,12 @@ class CallbacksTest < ActiveRecord::TestCase
       [ :after_destroy,               :string ],
       [ :after_destroy,               :proc   ],
       [ :after_destroy,               :object ],
-      [ :after_destroy,               :block  ]
+      [ :after_destroy,               :block  ],
+      [ :after_commit,                :block  ],
+      [ :after_commit,                :object ],
+      [ :after_commit,                :proc   ],
+      [ :after_commit,                :string ],
+      [ :after_commit,                :method ]
     ], david.history
   end
 
@@ -436,6 +451,7 @@ class CallbacksTest < ActiveRecord::TestCase
       assert !david.save
       exc = assert_raise(ActiveRecord::RecordNotSaved) { david.save! }
       assert_equal exc.record, david
+      assert_equal "Failed to save the record", exc.message
     end
 
     david = ImmutableDeveloper.find(1)
@@ -479,6 +495,7 @@ class CallbacksTest < ActiveRecord::TestCase
       assert !david.destroy
       exc = assert_raise(ActiveRecord::RecordNotDestroyed) { david.destroy! }
       assert_equal exc.record, david
+      assert_equal "Failed to destroy the record", exc.message
     end
     assert_not_nil ImmutableDeveloper.find_by_id(1)
 
diff --git a/activerecord/test/cases/collection_cache_key_test.rb b/activerecord/test/cases/collection_cache_key_test.rb
new file mode 100644
index 0000000000..53058c5a4a
--- /dev/null
+++ b/activerecord/test/cases/collection_cache_key_test.rb
@@ -0,0 +1,70 @@
+require "cases/helper"
+require "models/computer"
+require "models/developer"
+require "models/project"
+require "models/topic"
+require "models/post"
+require "models/comment"
+
+module ActiveRecord
+  class CollectionCacheKeyTest < ActiveRecord::TestCase
+    fixtures :developers, :projects, :developers_projects, :topics, :comments, :posts
+
+    test "collection_cache_key on model" do
+      assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/, Developer.collection_cache_key)
+    end
+
+    test "cache_key for relation" do
+      developers = Developer.where(name: "David")
+      last_developer_timestamp = developers.order(updated_at: :desc).first.updated_at
+
+      assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/, developers.cache_key)
+
+      /\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/ =~ developers.cache_key
+
+      assert_equal Digest::MD5.hexdigest(developers.to_sql), $1
+      assert_equal developers.count.to_s, $2
+      assert_equal last_developer_timestamp.to_s(ActiveRecord::Base.cache_timestamp_format), $3
+    end
+
+    test "it triggers at most one query" do
+      developers =  Developer.where(name: "David")
+
+      assert_queries(1) { developers.cache_key }
+      assert_queries(0) { developers.cache_key }
+    end
+
+    test "it doesn't trigger any query if the relation is already loaded" do
+      developers =  Developer.where(name: "David").load
+      assert_queries(0) { developers.cache_key }
+    end
+
+    test "relation cache_key changes when the sql query changes" do
+      developers = Developer.where(name: "David")
+      other_relation =  Developer.where(name: "David").where("1 = 1")
+
+      assert_not_equal developers.cache_key, other_relation.cache_key
+    end
+
+    test "cache_key for empty relation" do
+      developers = Developer.where(name: "Non Existent Developer")
+      assert_match(/\Adevelopers\/query-(\h+)-0\Z/, developers.cache_key)
+    end
+
+    test "cache_key with custom timestamp column" do
+      topics = Topic.where("title like ?", "%Topic%")
+      last_topic_timestamp = topics(:fifth).written_on.utc.to_s(:usec)
+      assert_match(last_topic_timestamp, topics.cache_key(:written_on))
+    end
+
+    test "cache_key with unknown timestamp column" do
+      topics = Topic.where("title like ?", "%Topic%")
+      assert_raises(ActiveRecord::StatementInvalid) { topics.cache_key(:published_at) }
+    end
+
+    test "collection proxy provides a cache_key" do
+      developers = projects(:active_record).developers
+      assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/, developers.cache_key)
+    end
+  end
+end
diff --git a/activerecord/test/cases/column_definition_test.rb b/activerecord/test/cases/column_definition_test.rb
index bcfd66b4bf..14b95ecab1 100644
--- a/activerecord/test/cases/column_definition_test.rb
+++ b/activerecord/test/cases/column_definition_test.rb
@@ -14,7 +14,7 @@ module ActiveRecord
       # Avoid column definitions in create table statements like:
       # `title` varchar(255) DEFAULT NULL
       def test_should_not_include_default_clause_when_default_is_null
-        column = Column.new("title", nil, Type::String.new(limit: 20))
+        column = Column.new("title", nil, SqlTypeMetadata.new(limit: 20))
         column_def = ColumnDefinition.new(
           column.name, "string",
           column.limit, column.precision, column.scale, column.default, column.null)
@@ -22,7 +22,7 @@ module ActiveRecord
       end
 
       def test_should_include_default_clause_when_default_is_present
-        column = Column.new("title", "Hello", Type::String.new(limit: 20))
+        column = Column.new("title", "Hello", SqlTypeMetadata.new(limit: 20))
         column_def = ColumnDefinition.new(
           column.name, "string",
           column.limit, column.precision, column.scale, column.default, column.null)
@@ -30,94 +30,53 @@ module ActiveRecord
       end
 
       def test_should_specify_not_null_if_null_option_is_false
-        column = Column.new("title", "Hello", Type::String.new(limit: 20), "varchar(20)", false)
+        type_metadata = SqlTypeMetadata.new(limit: 20)
+        column = Column.new("title", "Hello", type_metadata, false)
         column_def = ColumnDefinition.new(
           column.name, "string",
           column.limit, column.precision, column.scale, column.default, column.null)
           assert_equal %Q{title varchar(20) DEFAULT 'Hello' NOT NULL}, @viz.accept(column_def)
       end
 
-      if current_adapter?(:MysqlAdapter)
+      if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
         def test_should_set_default_for_mysql_binary_data_types
-          binary_column = MysqlAdapter::Column.new("title", "a", Type::Binary.new, "binary(1)")
+          type = SqlTypeMetadata.new(type: :binary, sql_type: "binary(1)")
+          binary_column = AbstractMysqlAdapter::Column.new("title", "a", type)
           assert_equal "a", binary_column.default
 
-          varbinary_column = MysqlAdapter::Column.new("title", "a", Type::Binary.new, "varbinary(1)")
+          type = SqlTypeMetadata.new(type: :binary, sql_type: "varbinary")
+          varbinary_column = AbstractMysqlAdapter::Column.new("title", "a", type)
           assert_equal "a", varbinary_column.default
         end
 
         def test_should_not_set_default_for_blob_and_text_data_types
           assert_raise ArgumentError do
-            MysqlAdapter::Column.new("title", "a", Type::Binary.new, "blob")
+            AbstractMysqlAdapter::Column.new("title", "a", SqlTypeMetadata.new(sql_type: "blob"))
           end
 
+          text_type = AbstractMysqlAdapter::MysqlTypeMetadata.new(
+            SqlTypeMetadata.new(type: :text))
           assert_raise ArgumentError do
-            MysqlAdapter::Column.new("title", "Hello", Type::Text.new)
+            AbstractMysqlAdapter::Column.new("title", "Hello", text_type)
           end
 
-          text_column = MysqlAdapter::Column.new("title", nil, Type::Text.new)
+          text_column = AbstractMysqlAdapter::Column.new("title", nil, text_type)
           assert_equal nil, text_column.default
 
-          not_null_text_column = MysqlAdapter::Column.new("title", nil, Type::Text.new, "text", false)
+          not_null_text_column = AbstractMysqlAdapter::Column.new("title", nil, text_type, false)
           assert_equal "", not_null_text_column.default
         end
 
         def test_has_default_should_return_false_for_blob_and_text_data_types
-          blob_column = MysqlAdapter::Column.new("title", nil, Type::Binary.new, "blob")
+          binary_type = SqlTypeMetadata.new(sql_type: "blob")
+          blob_column = AbstractMysqlAdapter::Column.new("title", nil, binary_type)
           assert !blob_column.has_default?
 
-          text_column = MysqlAdapter::Column.new("title", nil, Type::Text.new)
+          text_type = SqlTypeMetadata.new(type: :text)
+          text_column = AbstractMysqlAdapter::Column.new("title", nil, text_type)
           assert !text_column.has_default?
         end
       end
-
-      if current_adapter?(:Mysql2Adapter)
-        def test_should_set_default_for_mysql_binary_data_types
-          binary_column = Mysql2Adapter::Column.new("title", "a", Type::Binary.new, "binary(1)")
-          assert_equal "a", binary_column.default
-
-          varbinary_column = Mysql2Adapter::Column.new("title", "a", Type::Binary.new, "varbinary(1)")
-          assert_equal "a", varbinary_column.default
-        end
-
-        def test_should_not_set_default_for_blob_and_text_data_types
-          assert_raise ArgumentError do
-            Mysql2Adapter::Column.new("title", "a", Type::Binary.new, "blob")
-          end
-
-          assert_raise ArgumentError do
-            Mysql2Adapter::Column.new("title", "Hello", Type::Text.new)
-          end
-
-          text_column = Mysql2Adapter::Column.new("title", nil, Type::Text.new)
-          assert_equal nil, text_column.default
-
-          not_null_text_column = Mysql2Adapter::Column.new("title", nil, Type::Text.new, "text", false)
-          assert_equal "", not_null_text_column.default
-        end
-
-        def test_has_default_should_return_false_for_blob_and_text_data_types
-          blob_column = Mysql2Adapter::Column.new("title", nil, Type::Binary.new, "blob")
-          assert !blob_column.has_default?
-
-          text_column = Mysql2Adapter::Column.new("title", nil, Type::Text.new)
-          assert !text_column.has_default?
-        end
-      end
-
-      if current_adapter?(:PostgreSQLAdapter)
-        def test_bigint_column_should_map_to_integer
-          oid = PostgreSQLAdapter::OID::Integer.new
-          bigint_column = PostgreSQLColumn.new('number', nil, oid, "bigint")
-          assert_equal :integer, bigint_column.type
-        end
-
-        def test_smallint_column_should_map_to_integer
-          oid = PostgreSQLAdapter::OID::Integer.new
-          smallint_column = PostgreSQLColumn.new('number', nil, oid, "smallint")
-          assert_equal :integer, smallint_column.type
-        end
-      end
     end
   end
 end
diff --git a/activerecord/test/cases/connection_adapters/adapter_leasing_test.rb b/activerecord/test/cases/connection_adapters/adapter_leasing_test.rb
index 662e19f35e..580568c8ac 100644
--- a/activerecord/test/cases/connection_adapters/adapter_leasing_test.rb
+++ b/activerecord/test/cases/connection_adapters/adapter_leasing_test.rb
@@ -6,7 +6,7 @@ module ActiveRecord
       class Pool < ConnectionPool
         def insert_connection_for_test!(c)
           synchronize do
-            @connections << c
+            adopt_connection(c)
             @available.add c
           end
         end
@@ -24,7 +24,9 @@ module ActiveRecord
 
       def test_lease_twice
         assert @adapter.lease, 'should lease adapter'
-        assert_not @adapter.lease, 'should not lease adapter'
+        assert_raises(ActiveRecordError) do
+          @adapter.lease
+        end
       end
 
       def test_expire_mutates_in_use
diff --git a/activerecord/test/cases/connection_adapters/connection_handler_test.rb b/activerecord/test/cases/connection_adapters/connection_handler_test.rb
index b72f8ca88c..9b1865e8bb 100644
--- a/activerecord/test/cases/connection_adapters/connection_handler_test.rb
+++ b/activerecord/test/cases/connection_adapters/connection_handler_test.rb
@@ -46,6 +46,52 @@ module ActiveRecord
       def test_connection_pools
         assert_equal([@pool], @handler.connection_pools)
       end
+
+      if Process.respond_to?(:fork)
+        def test_connection_pool_per_pid
+          object_id = ActiveRecord::Base.connection.object_id
+
+          rd, wr = IO.pipe
+          rd.binmode
+          wr.binmode
+
+          pid = fork {
+            rd.close
+            wr.write Marshal.dump ActiveRecord::Base.connection.object_id
+            wr.close
+            exit!
+          }
+
+          wr.close
+
+          Process.waitpid pid
+          assert_not_equal object_id, Marshal.load(rd.read)
+          rd.close
+        end
+
+        def test_retrieve_connection_pool_copies_schema_cache_from_ancestor_pool
+          @pool.schema_cache = @pool.connection.schema_cache
+          @pool.schema_cache.add('posts')
+
+          rd, wr = IO.pipe
+          rd.binmode
+          wr.binmode
+
+          pid = fork {
+            rd.close
+            pool = @handler.retrieve_connection_pool(@klass)
+            wr.write Marshal.dump pool.schema_cache.size
+            wr.close
+            exit!
+          }
+
+          wr.close
+
+          Process.waitpid pid
+          assert_equal @pool.schema_cache.size, Marshal.load(rd.read)
+          rd.close
+        end
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb b/activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb
index 80244d1439..2749273884 100644
--- a/activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb
+++ b/activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb
@@ -22,6 +22,10 @@ module ActiveRecord
         assert_lookup_type :string, "SET('one', 'two', 'three')"
       end
 
+      def test_set_type_with_value_matching_other_type
+        assert_lookup_type :string, "SET('unicode', '8bit', 'none', 'time')"
+      end
+
       def test_enum_type_with_value_matching_other_type
         assert_lookup_type :string, "ENUM('unicode', '8bit', 'none')"
       end
diff --git a/activerecord/test/cases/connection_adapters/schema_cache_test.rb b/activerecord/test/cases/connection_adapters/schema_cache_test.rb
index c7531f5418..db832fe55d 100644
--- a/activerecord/test/cases/connection_adapters/schema_cache_test.rb
+++ b/activerecord/test/cases/connection_adapters/schema_cache_test.rb
@@ -29,7 +29,7 @@ module ActiveRecord
       def test_clearing
         @cache.columns('posts')
         @cache.columns_hash('posts')
-        @cache.tables('posts')
+        @cache.data_sources('posts')
         @cache.primary_keys('posts')
 
         @cache.clear!
@@ -40,17 +40,22 @@ module ActiveRecord
       def test_dump_and_load
         @cache.columns('posts')
         @cache.columns_hash('posts')
-        @cache.tables('posts')
+        @cache.data_sources('posts')
         @cache.primary_keys('posts')
 
         @cache = Marshal.load(Marshal.dump(@cache))
 
         assert_equal 11, @cache.columns('posts').size
         assert_equal 11, @cache.columns_hash('posts').size
-        assert @cache.tables('posts')
+        assert @cache.data_sources('posts')
         assert_equal 'id', @cache.primary_keys('posts')
       end
 
+      def test_table_methods_deprecation
+        assert_deprecated { assert @cache.table_exists?('posts') }
+        assert_deprecated { assert @cache.tables('posts') }
+        assert_deprecated { @cache.clear_table_cache!('posts') }
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/connection_adapters/type_lookup_test.rb b/activerecord/test/cases/connection_adapters/type_lookup_test.rb
index d5c1dc1e5d..7566863653 100644
--- a/activerecord/test/cases/connection_adapters/type_lookup_test.rb
+++ b/activerecord/test/cases/connection_adapters/type_lookup_test.rb
@@ -79,13 +79,22 @@ module ActiveRecord
         assert_lookup_type :integer, 'bigint'
       end
 
+      def test_bigint_limit
+        cast_type = @connection.type_map.lookup("bigint")
+        if current_adapter?(:OracleAdapter)
+          assert_equal 19, cast_type.limit
+        else
+          assert_equal 8, cast_type.limit
+        end
+      end
+
       def test_decimal_without_scale
         types = %w{decimal(2) decimal(2,0) numeric(2) numeric(2,0) number(2) number(2,0)}
         types.each do |type|
           cast_type = @connection.type_map.lookup(type)
 
           assert_equal :decimal, cast_type.type
-          assert_equal 2, cast_type.type_cast_from_user(2.1)
+          assert_equal 2, cast_type.cast(2.1)
         end
       end
 
diff --git a/activerecord/test/cases/connection_management_test.rb b/activerecord/test/cases/connection_management_test.rb
index f53c496ecd..dff6ea0fb0 100644
--- a/activerecord/test/cases/connection_management_test.rb
+++ b/activerecord/test/cases/connection_management_test.rb
@@ -26,29 +26,6 @@ module ActiveRecord
         assert ActiveRecord::Base.connection_handler.active_connections?
       end
 
-      if Process.respond_to?(:fork)
-        def test_connection_pool_per_pid
-          object_id = ActiveRecord::Base.connection.object_id
-
-          rd, wr = IO.pipe
-          rd.binmode
-          wr.binmode
-
-          pid = fork {
-            rd.close
-            wr.write Marshal.dump ActiveRecord::Base.connection.object_id
-            wr.close
-            exit!
-          }
-
-          wr.close
-
-          Process.waitpid pid
-          assert_not_equal object_id, Marshal.load(rd.read)
-          rd.close
-        end
-      end
-
       def test_app_delegation
         manager = ConnectionManagement.new(@app)
 
@@ -110,7 +87,7 @@ module ActiveRecord
         assert ActiveRecord::Base.connection_handler.active_connections?
       end
 
-      test "proxy is polite to it's body and responds to it" do
+      test "proxy is polite to its body and responds to it" do
         body = Class.new(String) { def to_path; "/path"; end }.new
         app = lambda { |_| [200, {}, body] }
         response_body = ConnectionManagement.new(app).call(@env)[2]
diff --git a/activerecord/test/cases/connection_pool_test.rb b/activerecord/test/cases/connection_pool_test.rb
index 8d15a76735..7ef5c93a48 100644
--- a/activerecord/test/cases/connection_pool_test.rb
+++ b/activerecord/test/cases/connection_pool_test.rb
@@ -1,5 +1,5 @@
 require "cases/helper"
-require 'active_support/concurrency/latch'
+require 'concurrent/atomics'
 
 module ActiveRecord
   module ConnectionAdapters
@@ -100,7 +100,7 @@ module ActiveRecord
         t = Thread.new { @pool.checkout }
 
         # make sure our thread is in the timeout section
-        Thread.pass until t.status == "sleep"
+        Thread.pass until @pool.num_waiting_in_queue == 1
 
         connection = cs.first
         connection.close
@@ -112,7 +112,7 @@ module ActiveRecord
         t = Thread.new { @pool.checkout }
 
         # make sure our thread is in the timeout section
-        Thread.pass until t.status == "sleep"
+        Thread.pass until @pool.num_waiting_in_queue == 1
 
         connection = cs.first
         @pool.remove connection
@@ -133,15 +133,15 @@ module ActiveRecord
       end
 
       def test_reap_inactive
-        ready = ActiveSupport::Concurrency::Latch.new
+        ready = Concurrent::CountDownLatch.new
         @pool.checkout
         child = Thread.new do
           @pool.checkout
           @pool.checkout
-          ready.release
+          ready.count_down
           Thread.stop
         end
-        ready.await
+        ready.wait
 
         assert_equal 3, active_connections(@pool).size
 
@@ -204,13 +204,13 @@ module ActiveRecord
       end
 
       # The connection pool is "fair" if threads waiting for
-      # connections receive them the order in which they began
+      # connections receive them in the order in which they began
       # waiting.  This ensures that we don't timeout one HTTP request
       # even while well under capacity in a multi-threaded environment
       # such as a Java servlet container.
       #
       # We don't need strict fairness: if two connections become
-      # available at the same time, it's fine of two threads that were
+      # available at the same time, it's fine if two threads that were
       # waiting acquire the connections out of order.
       #
       # Thus this test prepares waiting threads and then trickles in
@@ -234,7 +234,7 @@ module ActiveRecord
               mutex.synchronize { errors << e }
             end
           }
-          Thread.pass until t.status == "sleep"
+          Thread.pass until @pool.num_waiting_in_queue == i
           t
         end
 
@@ -271,7 +271,7 @@ module ActiveRecord
               mutex.synchronize { errors << e }
             end
           }
-          Thread.pass until t.status == "sleep"
+          Thread.pass until @pool.num_waiting_in_queue == i
           t
         end
 
@@ -341,6 +341,185 @@ module ActiveRecord
           handler.establish_connection anonymous, nil
         }
       end
+
+      def test_pool_sets_connection_schema_cache
+        connection = pool.checkout
+        schema_cache = SchemaCache.new connection
+        schema_cache.add(:posts)
+        pool.schema_cache = schema_cache
+
+        pool.with_connection do |conn|
+          assert_not_same pool.schema_cache, conn.schema_cache
+          assert_equal pool.schema_cache.size, conn.schema_cache.size
+          assert_same pool.schema_cache.columns(:posts), conn.schema_cache.columns(:posts)
+        end
+
+        pool.checkin connection
+      end
+
+      def test_concurrent_connection_establishment
+        assert_operator @pool.connections.size, :<=, 1
+
+        all_threads_in_new_connection = Concurrent::CountDownLatch.new(@pool.size - @pool.connections.size)
+        all_go                        = Concurrent::CountDownLatch.new
+
+        @pool.singleton_class.class_eval do
+          define_method(:new_connection) do
+            all_threads_in_new_connection.count_down
+            all_go.wait
+            super()
+          end
+        end
+
+        connecting_threads = []
+        @pool.size.times do
+          connecting_threads << Thread.new { @pool.checkout }
+        end
+
+        begin
+          Timeout.timeout(5) do
+            # the kernel of the whole test is here, everything else is just scaffolding,
+            # this latch will not be released unless conn. pool allows for concurrent
+            # connection creation
+            all_threads_in_new_connection.wait
+          end
+        rescue Timeout::Error
+          flunk 'pool unable to establish connections concurrently or implementation has ' <<
+                'changed, this test then needs to patch a different :new_connection method'
+        ensure
+          # clean up the threads
+          all_go.count_down
+          connecting_threads.map(&:join)
+        end
+      end
+
+      def test_non_bang_disconnect_and_clear_reloadable_connections_throw_exception_if_threads_dont_return_their_conns
+        @pool.checkout_timeout = 0.001 # no need to delay test suite by waiting the whole full default timeout
+        [:disconnect, :clear_reloadable_connections].each do |group_action_method|
+          @pool.with_connection do |connection|
+            assert_raises(ExclusiveConnectionTimeoutError) do
+              Thread.new { @pool.send(group_action_method) }.join
+            end
+          end
+        end
+      end
+
+      def test_disconnect_and_clear_reloadable_connections_attempt_to_wait_for_threads_to_return_their_conns
+        [:disconnect, :disconnect!, :clear_reloadable_connections, :clear_reloadable_connections!].each do |group_action_method|
+          begin
+            thread = timed_join_result = nil
+            @pool.with_connection do |connection|
+              thread = Thread.new { @pool.send(group_action_method) }
+
+              # give the other `thread` some time to get stuck in `group_action_method`
+              timed_join_result = thread.join(0.3)
+              # thread.join # => `nil` means the other thread hasn't finished running and is still waiting for us to
+              # release our connection
+              assert_nil timed_join_result
+
+              # assert that since this is within default timeout our connection hasn't been forcefully taken away from us
+              assert @pool.active_connection?
+            end
+          ensure
+            thread.join if thread && !timed_join_result # clean up the other thread
+          end
+        end
+      end
+
+      def test_bang_versions_of_disconnect_and_clear_reloadable_connections_if_unable_to_aquire_all_connections_proceed_anyway
+        @pool.checkout_timeout = 0.001 # no need to delay test suite by waiting the whole full default timeout
+        [:disconnect!, :clear_reloadable_connections!].each do |group_action_method|
+          @pool.with_connection do |connection|
+            Thread.new { @pool.send(group_action_method) }.join
+            # assert connection has been forcefully taken away from us
+            assert_not @pool.active_connection?
+          end
+        end
+      end
+
+      def test_disconnect_and_clear_reloadable_connections_are_able_to_preempt_other_waiting_threads
+        with_single_connection_pool do |pool|
+          [:disconnect, :disconnect!, :clear_reloadable_connections, :clear_reloadable_connections!].each do |group_action_method|
+            conn               = pool.connection # drain the only available connection
+            second_thread_done = Concurrent::CountDownLatch.new
+
+            # create a first_thread and let it get into the FIFO queue first
+            first_thread = Thread.new do
+              pool.with_connection { second_thread_done.wait }
+            end
+
+            # wait for first_thread to get in queue
+            Thread.pass until pool.num_waiting_in_queue == 1
+
+            # create a different, later thread, that will attempt to do a "group action",
+            # but because of the group action semantics it should be able to preempt the
+            # first_thread when a connection is made available
+            second_thread = Thread.new do
+              pool.send(group_action_method)
+              second_thread_done.count_down
+            end
+
+            # wait for second_thread to get in queue
+            Thread.pass until pool.num_waiting_in_queue == 2
+
+            # return the only available connection
+            pool.checkin(conn)
+
+            # if the second_thread is not able to preempt the first_thread,
+            # they will temporarily (until either of them timeouts with ConnectionTimeoutError)
+            # deadlock and a join(2) timeout will be reached
+            failed = true unless second_thread.join(2)
+
+            #--- post test clean up start
+            second_thread_done.count_down if failed
+
+            # after `pool.disconnect()` the first thread will be left stuck in queue, no need to wait for
+            # it to timeout with ConnectionTimeoutError
+            if (group_action_method == :disconnect || group_action_method == :disconnect!) && pool.num_waiting_in_queue > 0
+              pool.with_connection {} # create a new connection in case there are threads still stuck in a queue
+            end
+
+            first_thread.join
+            second_thread.join
+            #--- post test clean up end
+
+            flunk "#{group_action_method} is not able to preempt other waiting threads" if failed
+          end
+        end
+      end
+
+      def test_clear_reloadable_connections_creates_new_connections_for_waiting_threads_if_necessary
+        with_single_connection_pool do |pool|
+          conn = pool.connection # drain the only available connection
+          def conn.requires_reloading? # make sure it gets removed from the pool by clear_reloadable_connections
+            true
+          end
+
+          stuck_thread = Thread.new do
+            pool.with_connection {}
+          end
+
+          # wait for stuck_thread to get in queue
+          Thread.pass until pool.num_waiting_in_queue == 1
+
+          pool.clear_reloadable_connections
+
+          unless stuck_thread.join(2)
+            flunk 'clear_reloadable_connections must not let other connection waiting threads get stuck in queue'
+          end
+
+          assert_equal 0, pool.num_waiting_in_queue
+        end
+      end
+
+      private
+      def with_single_connection_pool
+        one_conn_spec = ActiveRecord::Base.connection_pool.spec.dup
+        one_conn_spec.config[:pool] = 1 # this is safe to do, because .dupped ConnectionSpecification also auto-dups its config
+        yield(pool = ConnectionPool.new(one_conn_spec))
+      ensure
+        pool.disconnect! if pool
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/core_test.rb b/activerecord/test/cases/core_test.rb
index 715d92af99..3cb98832c5 100644
--- a/activerecord/test/cases/core_test.rb
+++ b/activerecord/test/cases/core_test.rb
@@ -98,4 +98,15 @@ class CoreTest < ActiveRecord::TestCase
     assert actual.start_with?(expected.split('XXXXXX').first)
     assert actual.end_with?(expected.split('XXXXXX').last)
   end
+
+  def test_pretty_print_overridden_by_inspect
+    subtopic = Class.new(Topic) do
+      def inspect
+        "inspecting topic"
+      end
+    end
+    actual = ''
+    PP.pp(subtopic.new, StringIO.new(actual))
+    assert_equal "inspecting topic\n", actual
+  end
 end
diff --git a/activerecord/test/cases/counter_cache_test.rb b/activerecord/test/cases/counter_cache_test.rb
index 07a182070b..922cb59280 100644
--- a/activerecord/test/cases/counter_cache_test.rb
+++ b/activerecord/test/cases/counter_cache_test.rb
@@ -1,6 +1,7 @@
 require 'cases/helper'
 require 'models/topic'
 require 'models/car'
+require 'models/aircraft'
 require 'models/wheel'
 require 'models/engine'
 require 'models/reply'
@@ -180,4 +181,34 @@ class CounterCacheTest < ActiveRecord::TestCase
       SpecialTopic.reset_counters(special.id, :lightweight_special_replies)
     end
   end
+
+  test "counters are updated both in memory and in the database on create" do
+    car = Car.new(engines_count: 0)
+    car.engines = [Engine.new, Engine.new]
+    car.save!
+
+    assert_equal 2, car.engines_count
+    assert_equal 2, car.reload.engines_count
+  end
+
+  test "counter caches are updated in memory when the default value is nil" do
+    car = Car.new(engines_count: nil)
+    car.engines = [Engine.new, Engine.new]
+    car.save!
+
+    assert_equal 2, car.engines_count
+    assert_equal 2, car.reload.engines_count
+  end
+
+  test "update counters in a polymorphic relationship" do
+    aircraft = Aircraft.create!
+
+    assert_difference 'aircraft.reload.wheels_count' do
+      aircraft.wheels << Wheel.create!
+    end
+
+    assert_difference 'aircraft.reload.wheels_count', -1 do
+      aircraft.wheels.first.destroy
+    end
+  end
 end
diff --git a/activerecord/test/cases/date_time_precision_test.rb b/activerecord/test/cases/date_time_precision_test.rb
new file mode 100644
index 0000000000..698f1b852e
--- /dev/null
+++ b/activerecord/test/cases/date_time_precision_test.rb
@@ -0,0 +1,111 @@
+require 'cases/helper'
+require 'support/schema_dumping_helper'
+
+if ActiveRecord::Base.connection.supports_datetime_with_precision?
+class DateTimePrecisionTest < ActiveRecord::TestCase
+  include SchemaDumpingHelper
+  self.use_transactional_tests = false
+
+  class Foo < ActiveRecord::Base; end
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+  end
+
+  teardown do
+    @connection.drop_table :foos, if_exists: true
+  end
+
+  def test_datetime_data_type_with_precision
+    @connection.create_table(:foos, force: true)
+    @connection.add_column :foos, :created_at, :datetime, precision: 0
+    @connection.add_column :foos, :updated_at, :datetime, precision: 5
+    assert_equal 0, activerecord_column_option('foos', 'created_at', 'precision')
+    assert_equal 5, activerecord_column_option('foos', 'updated_at', 'precision')
+  end
+
+  def test_timestamps_helper_with_custom_precision
+    @connection.create_table(:foos, force: true) do |t|
+      t.timestamps precision: 4
+    end
+    assert_equal 4, activerecord_column_option('foos', 'created_at', 'precision')
+    assert_equal 4, activerecord_column_option('foos', 'updated_at', 'precision')
+  end
+
+  def test_passing_precision_to_datetime_does_not_set_limit
+    @connection.create_table(:foos, force: true) do |t|
+      t.timestamps precision: 4
+    end
+    assert_nil activerecord_column_option('foos', 'created_at', 'limit')
+    assert_nil activerecord_column_option('foos', 'updated_at', 'limit')
+  end
+
+  def test_invalid_datetime_precision_raises_error
+    assert_raises ActiveRecord::ActiveRecordError do
+      @connection.create_table(:foos, force: true) do |t|
+        t.timestamps precision: 7
+      end
+    end
+  end
+
+  def test_database_agrees_with_activerecord_about_precision
+    @connection.create_table(:foos, force: true) do |t|
+      t.timestamps precision: 4
+    end
+    assert_equal 4, database_datetime_precision('foos', 'created_at')
+    assert_equal 4, database_datetime_precision('foos', 'updated_at')
+  end
+
+  def test_formatting_datetime_according_to_precision
+    @connection.create_table(:foos, force: true) do |t|
+      t.datetime :created_at, precision: 0
+      t.datetime :updated_at, precision: 4
+    end
+    date = ::Time.utc(2014, 8, 17, 12, 30, 0, 999999)
+    Foo.create!(created_at: date, updated_at: date)
+    assert foo = Foo.find_by(created_at: date)
+    assert_equal 1, Foo.where(updated_at: date).count
+    assert_equal date.to_s, foo.created_at.to_s
+    assert_equal date.to_s, foo.updated_at.to_s
+    assert_equal 000000, foo.created_at.usec
+    assert_equal 999900, foo.updated_at.usec
+  end
+
+  def test_schema_dump_includes_datetime_precision
+    @connection.create_table(:foos, force: true) do |t|
+      t.timestamps precision: 6
+    end
+    output = dump_table_schema("foos")
+    assert_match %r{t\.datetime\s+"created_at",\s+precision: 6,\s+null: false$}, output
+    assert_match %r{t\.datetime\s+"updated_at",\s+precision: 6,\s+null: false$}, output
+  end
+
+  if current_adapter?(:PostgreSQLAdapter)
+    def test_datetime_precision_with_zero_should_be_dumped
+      @connection.create_table(:foos, force: true) do |t|
+        t.timestamps precision: 0
+      end
+      output = dump_table_schema("foos")
+      assert_match %r{t\.datetime\s+"created_at",\s+precision: 0,\s+null: false$}, output
+      assert_match %r{t\.datetime\s+"updated_at",\s+precision: 0,\s+null: false$}, output
+    end
+  end
+
+  private
+
+  def database_datetime_precision(table_name, column_name)
+    results = @connection.exec_query("SELECT column_name, datetime_precision FROM information_schema.columns WHERE table_name = '#{table_name}'")
+    result = results.find do |result_hash|
+      result_hash["column_name"] == column_name
+    end
+    result && result["datetime_precision"].to_i
+  end
+
+  def activerecord_column_option(tablename, column_name, option)
+    result = @connection.columns(tablename).find do |column|
+      column.name == column_name
+    end
+    result && result.send(option)
+  end
+end
+end
diff --git a/activerecord/test/cases/date_time_test.rb b/activerecord/test/cases/date_time_test.rb
index 330232cee2..4cbff564aa 100644
--- a/activerecord/test/cases/date_time_test.rb
+++ b/activerecord/test/cases/date_time_test.rb
@@ -55,7 +55,7 @@ class DateTimeTest < ActiveRecord::TestCase
     now = DateTime.now
     with_timezone_config default: :local do
       task = Task.new starting: now
-      assert now, task.starting
+      assert_equal now, task.starting
     end
   end
 end
diff --git a/activerecord/test/cases/defaults_test.rb b/activerecord/test/cases/defaults_test.rb
index e9bc583bf4..67fddebf45 100644
--- a/activerecord/test/cases/defaults_test.rb
+++ b/activerecord/test/cases/defaults_test.rb
@@ -40,7 +40,7 @@ class DefaultNumbersTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.drop_table "default_numbers" if @connection.table_exists? 'default_numbers'
+    @connection.drop_table :default_numbers, if_exists: true
   end
 
   def test_default_positive_integer
@@ -90,14 +90,14 @@ end
 if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
   class DefaultsTestWithoutTransactionalFixtures < ActiveRecord::TestCase
     # ActiveRecord::Base#create! (and #save and other related methods) will
-    # open a new transaction. When in transactional fixtures mode, this will
+    # open a new transaction. When in transactional tests mode, this will
     # cause Active Record to create a new savepoint. However, since MySQL doesn't
     # support DDL transactions, creating a table will result in any created
     # savepoints to be automatically released. This in turn causes the savepoint
     # release code in AbstractAdapter#transaction to fail.
     #
-    # We don't want that to happen, so we disable transactional fixtures here.
-    self.use_transactional_fixtures = false
+    # We don't want that to happen, so we disable transactional tests here.
+    self.use_transactional_tests = false
 
     def using_strict(strict)
       connection = ActiveRecord::Base.remove_connection
diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index ae4a8aab2c..cd1967c373 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -89,7 +89,7 @@ class DirtyTest < ActiveRecord::TestCase
       target = Class.new(ActiveRecord::Base)
       target.table_name = 'pirates'
 
-      pirate = target.create
+      pirate = target.create!
       pirate.created_on = pirate.created_on
       assert !pirate.created_on_changed?
     end
@@ -467,8 +467,10 @@ class DirtyTest < ActiveRecord::TestCase
       topic.save!
 
       updated_at = topic.updated_at
-      topic.content[:hello] = 'world'
-      topic.save!
+      travel(1.second) do
+        topic.content[:hello] = 'world'
+        topic.save!
+      end
 
       assert_not_equal updated_at, topic.updated_at
       assert_equal 'world', topic.content[:hello]
@@ -521,6 +523,9 @@ class DirtyTest < ActiveRecord::TestCase
     assert_equal Hash.new, pirate.previous_changes
 
     pirate = Pirate.find_by_catchphrase("arrr")
+
+    travel(1.second)
+
     pirate.catchphrase = "Me Maties!"
     pirate.save!
 
@@ -532,6 +537,9 @@ class DirtyTest < ActiveRecord::TestCase
     assert !pirate.previous_changes.key?('created_on')
 
     pirate = Pirate.find_by_catchphrase("Me Maties!")
+
+    travel(1.second)
+
     pirate.catchphrase = "Thar She Blows!"
     pirate.save
 
@@ -542,6 +550,8 @@ class DirtyTest < ActiveRecord::TestCase
     assert !pirate.previous_changes.key?('parrot_id')
     assert !pirate.previous_changes.key?('created_on')
 
+    travel(1.second)
+
     pirate = Pirate.find_by_catchphrase("Thar She Blows!")
     pirate.update(catchphrase: "Ahoy!")
 
@@ -552,6 +562,8 @@ class DirtyTest < ActiveRecord::TestCase
     assert !pirate.previous_changes.key?('parrot_id')
     assert !pirate.previous_changes.key?('created_on')
 
+    travel(1.second)
+
     pirate = Pirate.find_by_catchphrase("Ahoy!")
     pirate.update_attribute(:catchphrase, "Ninjas suck!")
 
@@ -561,6 +573,8 @@ class DirtyTest < ActiveRecord::TestCase
     assert_not_nil pirate.previous_changes['updated_on'][1]
     assert !pirate.previous_changes.key?('parrot_id')
     assert !pirate.previous_changes.key?('created_on')
+  ensure
+    travel_back
   end
 
   if ActiveRecord::Base.connection.supports_migrations?
@@ -578,6 +592,7 @@ class DirtyTest < ActiveRecord::TestCase
   end
 
   def test_datetime_attribute_can_be_updated_with_fractional_seconds
+    skip "Fractional seconds are not supported" unless subsecond_precision_supported?
     in_time_zone 'Paris' do
       target = Class.new(ActiveRecord::Base)
       target.table_name = 'topics'
@@ -623,32 +638,6 @@ class DirtyTest < ActiveRecord::TestCase
     end
   end
 
-  test "defaults with type that implements `type_cast_for_database`" do
-    type = Class.new(ActiveRecord::Type::Value) do
-      def type_cast(value)
-        value.to_i
-      end
-
-      def type_cast_for_database(value)
-        value.to_s
-      end
-    end
-
-    model_class = Class.new(ActiveRecord::Base) do
-      self.table_name = 'numeric_data'
-      attribute :foo, type.new, default: 1
-    end
-
-    model = model_class.new
-    assert_not model.foo_changed?
-
-    model = model_class.new(foo: 1)
-    assert_not model.foo_changed?
-
-    model = model_class.new(foo: '1')
-    assert_not model.foo_changed?
-  end
-
   test "in place mutation detection" do
     pirate = Pirate.create!(catchphrase: "arrrr")
     pirate.catchphrase << " matey!"
@@ -711,7 +700,7 @@ class DirtyTest < ActiveRecord::TestCase
   test "attribute_will_change! doesn't try to save non-persistable attributes" do
     klass = Class.new(ActiveRecord::Base) do
       self.table_name = 'people'
-      attribute :non_persisted_attribute, ActiveRecord::Type::String.new
+      attribute :non_persisted_attribute, :string
     end
 
     record = klass.new(first_name: "Sean")
@@ -721,6 +710,30 @@ class DirtyTest < ActiveRecord::TestCase
     assert record.save
   end
 
+  test "mutating and then assigning doesn't remove the change" do
+    pirate = Pirate.create!(catchphrase: "arrrr")
+    pirate.catchphrase << " matey!"
+    pirate.catchphrase = "arrrr matey!"
+
+    assert pirate.catchphrase_changed?(from: "arrrr", to: "arrrr matey!")
+  end
+
+  test "getters with side effects are allowed" do
+    klass = Class.new(Pirate) do
+      def catchphrase
+        if super.blank?
+          update_attribute(:catchphrase, "arr") # what could possibly go wrong?
+        end
+        super
+      end
+    end
+
+    pirate = klass.create!(catchphrase: "lol")
+    pirate.update_attribute(:catchphrase, nil)
+
+    assert_equal "arr", pirate.catchphrase
+  end
+
   private
     def with_partial_writes(klass, on = true)
       old = klass.partial_writes?
diff --git a/activerecord/test/cases/disconnected_test.rb b/activerecord/test/cases/disconnected_test.rb
index 94447addc1..c25089a420 100644
--- a/activerecord/test/cases/disconnected_test.rb
+++ b/activerecord/test/cases/disconnected_test.rb
@@ -4,7 +4,7 @@ class TestRecord < ActiveRecord::Base
 end
 
 class TestDisconnectedAdapter < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def setup
     @connection = ActiveRecord::Base.connection
@@ -21,7 +21,9 @@ class TestDisconnectedAdapter < ActiveRecord::TestCase
       @connection.execute "SELECT count(*) from products"
       @connection.disconnect!
       assert_raises(ActiveRecord::StatementInvalid) do
-        @connection.execute "SELECT count(*) from products"
+        silence_warnings do
+          @connection.execute "SELECT count(*) from products"
+        end
       end
     end
   end
diff --git a/activerecord/test/cases/enum_test.rb b/activerecord/test/cases/enum_test.rb
index 346fcab6ea..7c930de97b 100644
--- a/activerecord/test/cases/enum_test.rb
+++ b/activerecord/test/cases/enum_test.rb
@@ -9,26 +9,83 @@ class EnumTest < ActiveRecord::TestCase
   end
 
   test "query state by predicate" do
-    assert @book.proposed?
+    assert @book.published?
     assert_not @book.written?
-    assert_not @book.published?
+    assert_not @book.proposed?
 
-    assert @book.unread?
+    assert @book.read?
+    assert @book.in_english?
+    assert @book.author_visibility_visible?
+    assert @book.illustrator_visibility_visible?
+    assert @book.with_medium_font_size?
   end
 
   test "query state with strings" do
-    assert_equal "proposed", @book.status
-    assert_equal "unread", @book.read_status
+    assert_equal "published", @book.status
+    assert_equal "read", @book.read_status
+    assert_equal "english", @book.language
+    assert_equal "visible", @book.author_visibility
+    assert_equal "visible", @book.illustrator_visibility
   end
 
   test "find via scope" do
-    assert_equal @book, Book.proposed.first
-    assert_equal @book, Book.unread.first
+    assert_equal @book, Book.published.first
+    assert_equal @book, Book.read.first
+    assert_equal @book, Book.in_english.first
+    assert_equal @book, Book.author_visibility_visible.first
+    assert_equal @book, Book.illustrator_visibility_visible.first
+  end
+
+  test "find via where with values" do
+    published, written = Book.statuses[:published], Book.statuses[:written]
+
+    assert_equal @book, Book.where(status: published).first
+    assert_not_equal @book, Book.where(status: written).first
+    assert_equal @book, Book.where(status: [published]).first
+    assert_not_equal @book, Book.where(status: [written]).first
+    assert_not_equal @book, Book.where("status <> ?", published).first
+    assert_equal @book, Book.where("status <> ?", written).first
+  end
+
+  test "find via where with symbols" do
+    assert_equal @book, Book.where(status: :published).first
+    assert_not_equal @book, Book.where(status: :written).first
+    assert_equal @book, Book.where(status: [:published]).first
+    assert_not_equal @book, Book.where(status: [:written]).first
+    assert_not_equal @book, Book.where.not(status: :published).first
+    assert_equal @book, Book.where.not(status: :written).first
+  end
+
+  test "find via where with strings" do
+    assert_equal @book, Book.where(status: "published").first
+    assert_not_equal @book, Book.where(status: "written").first
+    assert_equal @book, Book.where(status: ["published"]).first
+    assert_not_equal @book, Book.where(status: ["written"]).first
+    assert_not_equal @book, Book.where.not(status: "published").first
+    assert_equal @book, Book.where.not(status: "written").first
+  end
+
+  test "build from scope" do
+    assert Book.written.build.written?
+    assert_not Book.written.build.proposed?
+  end
+
+  test "build from where" do
+    assert Book.where(status: Book.statuses[:written]).build.written?
+    assert_not Book.where(status: Book.statuses[:written]).build.proposed?
+    assert Book.where(status: :written).build.written?
+    assert_not Book.where(status: :written).build.proposed?
+    assert Book.where(status: "written").build.written?
+    assert_not Book.where(status: "written").build.proposed?
   end
 
   test "update by declaration" do
     @book.written!
     assert @book.written?
+    @book.in_english!
+    assert @book.in_english?
+    @book.author_visibility_visible!
+    assert @book.author_visibility_visible?
   end
 
   test "update by setter" do
@@ -53,42 +110,61 @@ class EnumTest < ActiveRecord::TestCase
 
   test "enum changed attributes" do
     old_status = @book.status
-    @book.status = :published
+    old_language = @book.language
+    @book.status = :proposed
+    @book.language = :spanish
     assert_equal old_status, @book.changed_attributes[:status]
+    assert_equal old_language, @book.changed_attributes[:language]
   end
 
   test "enum changes" do
     old_status = @book.status
-    @book.status = :published
-    assert_equal [old_status, 'published'], @book.changes[:status]
+    old_language = @book.language
+    @book.status = :proposed
+    @book.language = :spanish
+    assert_equal [old_status, 'proposed'], @book.changes[:status]
+    assert_equal [old_language, 'spanish'], @book.changes[:language]
   end
 
   test "enum attribute was" do
     old_status = @book.status
+    old_language = @book.language
     @book.status = :published
+    @book.language = :spanish
     assert_equal old_status, @book.attribute_was(:status)
+    assert_equal old_language, @book.attribute_was(:language)
   end
 
   test "enum attribute changed" do
-    @book.status = :published
+    @book.status = :proposed
+    @book.language = :french
     assert @book.attribute_changed?(:status)
+    assert @book.attribute_changed?(:language)
   end
 
   test "enum attribute changed to" do
-    @book.status = :published
-    assert @book.attribute_changed?(:status, to: 'published')
+    @book.status = :proposed
+    @book.language = :french
+    assert @book.attribute_changed?(:status, to: 'proposed')
+    assert @book.attribute_changed?(:language, to: 'french')
   end
 
   test "enum attribute changed from" do
     old_status = @book.status
-    @book.status = :published
+    old_language = @book.language
+    @book.status = :proposed
+    @book.language = :french
     assert @book.attribute_changed?(:status, from: old_status)
+    assert @book.attribute_changed?(:language, from: old_language)
   end
 
   test "enum attribute changed from old status to new status" do
     old_status = @book.status
-    @book.status = :published
-    assert @book.attribute_changed?(:status, from: old_status, to: 'published')
+    old_language = @book.language
+    @book.status = :proposed
+    @book.language = :french
+    assert @book.attribute_changed?(:status, from: old_status, to: 'proposed')
+    assert @book.attribute_changed?(:language, from: old_language, to: 'french')
   end
 
   test "enum didn't change" do
@@ -98,7 +174,7 @@ class EnumTest < ActiveRecord::TestCase
   end
 
   test "persist changes that are dirty" do
-    @book.status = :published
+    @book.status = :proposed
     assert @book.attribute_changed?(:status)
     @book.status = :written
     assert @book.attribute_changed?(:status)
@@ -106,7 +182,7 @@ class EnumTest < ActiveRecord::TestCase
 
   test "reverted changes that are not dirty" do
     old_status = @book.status
-    @book.status = :published
+    @book.status = :proposed
     assert @book.attribute_changed?(:status)
     @book.status = old_status
     assert_not @book.attribute_changed?(:status)
@@ -129,19 +205,24 @@ class EnumTest < ActiveRecord::TestCase
     assert_equal "'unknown' is not a valid status", e.message
   end
 
+  test "NULL values from database should be casted to nil" do
+    Book.where(id: @book.id).update_all("status = NULL")
+    assert_nil @book.reload.status
+  end
+
   test "assign nil value" do
     @book.status = nil
-    assert @book.status.nil?
+    assert_nil @book.status
   end
 
   test "assign empty string value" do
     @book.status = ''
-    assert @book.status.nil?
+    assert_nil @book.status
   end
 
   test "assign long empty string value" do
     @book.status = '   '
-    assert @book.status.nil?
+    assert_nil @book.status
   end
 
   test "constant to access the mapping" do
@@ -153,15 +234,23 @@ class EnumTest < ActiveRecord::TestCase
   test "building new objects with enum scopes" do
     assert Book.written.build.written?
     assert Book.read.build.read?
+    assert Book.in_spanish.build.in_spanish?
+    assert Book.illustrator_visibility_invisible.build.illustrator_visibility_invisible?
   end
 
   test "creating new objects with enum scopes" do
     assert Book.written.create.written?
     assert Book.read.create.read?
+    assert Book.in_spanish.create.in_spanish?
+    assert Book.illustrator_visibility_invisible.create.illustrator_visibility_invisible?
   end
 
   test "_before_type_cast returns the enum label (required for form fields)" do
-    assert_equal "proposed", @book.status_before_type_cast
+    if @book.status_came_from_user?
+      assert_equal "published", @book.status_before_type_cast
+    else
+      assert_equal "published", @book.status
+    end
   end
 
   test "reserved enum names" do
@@ -177,9 +266,10 @@ class EnumTest < ActiveRecord::TestCase
     ]
 
     conflicts.each_with_index do |name, i|
-      assert_raises(ArgumentError, "enum name `#{name}` should not be allowed") do
+      e = assert_raises(ArgumentError) do
         klass.class_eval { enum name => ["value_#{i}"] }
       end
+      assert_match(/You tried to define an enum named \"#{name}\" on the model/, e.message)
     end
   end
 
@@ -199,9 +289,10 @@ class EnumTest < ActiveRecord::TestCase
     ]
 
     conflicts.each_with_index do |value, i|
-      assert_raises(ArgumentError, "enum value `#{value}` should not be allowed") do
+      e = assert_raises(ArgumentError, "enum value `#{value}` should not be allowed") do
         klass.class_eval { enum "status_#{i}" => [value] }
       end
+      assert_match(/You tried to define an enum named .* on the model/, e.message)
     end
   end
 
@@ -287,4 +378,37 @@ class EnumTest < ActiveRecord::TestCase
     book2.status = :uploaded
     assert_equal ['drafted', 'uploaded'], book2.status_change
   end
+
+  test "declare multiple enums at a time" do
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = "books"
+      enum status: [:proposed, :written, :published],
+           nullable_status: [:single, :married]
+    end
+
+    book1 = klass.proposed.create!
+    assert book1.proposed?
+
+    book2 = klass.single.create!
+    assert book2.single?
+  end
+
+  test "query state by predicate with prefix" do
+    assert @book.author_visibility_visible?
+    assert_not @book.author_visibility_invisible?
+    assert @book.illustrator_visibility_visible?
+    assert_not @book.illustrator_visibility_invisible?
+  end
+
+  test "query state by predicate with custom prefix" do
+    assert @book.in_english?
+    assert_not @book.in_spanish?
+    assert_not @book.in_french?
+  end
+
+  test "uses default status when no status is provided in fixtures" do
+    book = books(:tlg)
+    assert book.proposed?, "expected fixture to default to proposed status"
+    assert book.in_english?, "expected fixture to default to english language"
+  end
 end
diff --git a/activerecord/test/cases/errors_test.rb b/activerecord/test/cases/errors_test.rb
new file mode 100644
index 0000000000..0711a372f2
--- /dev/null
+++ b/activerecord/test/cases/errors_test.rb
@@ -0,0 +1,16 @@
+require_relative "../cases/helper"
+
+class ErrorsTest < ActiveRecord::TestCase
+  def test_can_be_instantiated_with_no_args
+    base = ActiveRecord::ActiveRecordError
+    error_klasses = ObjectSpace.each_object(Class).select { |klass| klass < base }
+
+    error_klasses.each do |error_klass|
+      begin
+        error_klass.new.inspect
+      rescue ArgumentError
+        raise "Instance of #{error_klass} can't be initialized with no arguments"
+      end
+    end
+  end
+end
diff --git a/activerecord/test/cases/explain_subscriber_test.rb b/activerecord/test/cases/explain_subscriber_test.rb
index 8de2ddb10d..2dee8a26a5 100644
--- a/activerecord/test/cases/explain_subscriber_test.rb
+++ b/activerecord/test/cases/explain_subscriber_test.rb
@@ -48,6 +48,11 @@ if ActiveRecord::Base.connection.supports_explain?
       assert queries.empty?
     end
 
+    def test_collects_cte_queries
+      SUBSCRIBER.finish(nil, nil, name: 'SQL', sql: 'with s as (values(3)) select 1 from s')
+      assert_equal 1, queries.size
+    end
+
     teardown do
       ActiveRecord::ExplainRegistry.reset
     end
diff --git a/activerecord/test/cases/explain_test.rb b/activerecord/test/cases/explain_test.rb
index 9d25bdd82a..64dfd86ce2 100644
--- a/activerecord/test/cases/explain_test.rb
+++ b/activerecord/test/cases/explain_test.rb
@@ -28,7 +28,7 @@ if ActiveRecord::Base.connection.supports_explain?
       assert_match "SELECT", sql
       if binds.any?
         assert_equal 1, binds.length
-        assert_equal "honda", binds.flatten.last
+        assert_equal "honda", binds.last.value
       else
         assert_match 'honda', sql
       end
@@ -39,38 +39,49 @@ if ActiveRecord::Base.connection.supports_explain?
       binds   = [[], []]
       queries = sqls.zip(binds)
 
-      connection.stubs(:explain).returns('query plan foo', 'query plan bar')
-      expected = sqls.map {|sql| "EXPLAIN for: #{sql}\nquery plan #{sql}"}.join("\n")
-      assert_equal expected, base.exec_explain(queries)
+      stub_explain_for_query_plans do
+        expected = sqls.map {|sql| "EXPLAIN for: #{sql}\nquery plan #{sql}"}.join("\n")
+        assert_equal expected, base.exec_explain(queries)
+      end
     end
 
     def test_exec_explain_with_binds
-      cols = [Object.new, Object.new]
-      cols[0].expects(:name).returns('wadus')
-      cols[1].expects(:name).returns('chaflan')
+      object = Struct.new(:name)
+      cols = [object.new('wadus'), object.new('chaflan')]
 
       sqls    = %w(foo bar)
       binds   = [[[cols[0], 1]], [[cols[1], 2]]]
       queries = sqls.zip(binds)
 
-      connection.stubs(:explain).returns("query plan foo\n", "query plan bar\n")
-      expected = <<-SQL.strip_heredoc
-        EXPLAIN for: #{sqls[0]} [["wadus", 1]]
-        query plan foo
+      stub_explain_for_query_plans(["query plan foo\n", "query plan bar\n"]) do
+        expected = <<-SQL.strip_heredoc
+          EXPLAIN for: #{sqls[0]} [["wadus", 1]]
+          query plan foo
 
-        EXPLAIN for: #{sqls[1]} [["chaflan", 2]]
-        query plan bar
-      SQL
-      assert_equal expected, base.exec_explain(queries)
+          EXPLAIN for: #{sqls[1]} [["chaflan", 2]]
+          query plan bar
+        SQL
+        assert_equal expected, base.exec_explain(queries)
+      end
     end
 
     def test_unsupported_connection_adapter
-      connection.stubs(:supports_explain?).returns(false)
+      connection.stub(:supports_explain?, false) do
+        assert_not_called(base.logger, :warn) do
+          Car.where(:name => 'honda').to_a
+        end
+      end
+    end
 
-      base.logger.expects(:warn).never
+    private
 
-      Car.where(:name => 'honda').to_a
-    end
+      def stub_explain_for_query_plans(query_plans = ['query plan foo', 'query plan bar'])
+        explain_called = 0
+
+        connection.stub(:explain, proc{ explain_called += 1; query_plans[explain_called - 1] }) do
+          yield
+        end
+      end
 
   end
 end
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index 39308866ee..6686ce012d 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -178,8 +178,9 @@ class FinderTest < ActiveRecord::TestCase
   end
 
   def test_exists_does_not_instantiate_records
-    Developer.expects(:instantiate).never
-    Developer.exists?
+    assert_not_called(Developer, :instantiate) do
+      Developer.exists?
+    end
   end
 
   def test_find_by_array_of_one_id
@@ -264,6 +265,12 @@ class FinderTest < ActiveRecord::TestCase
     assert_equal [Account], accounts.collect(&:class).uniq
   end
 
+  def test_find_by_association_subquery
+    author = authors(:david)
+    assert_equal author.post, Post.find_by(author: Author.where(id: author))
+    assert_equal author.post, Post.find_by(author_id: Author.where(id: author))
+  end
+
   def test_take
     assert_equal topics(:first), Topic.take
   end
@@ -700,12 +707,12 @@ class FinderTest < ActiveRecord::TestCase
   end
 
   def test_bind_arity
-    assert_nothing_raised                                 { bind '' }
+    assert_nothing_raised                                { bind '' }
     assert_raise(ActiveRecord::PreparedStatementInvalid) { bind '', 1 }
 
     assert_raise(ActiveRecord::PreparedStatementInvalid) { bind '?' }
-    assert_nothing_raised                                 { bind '?', 1 }
-    assert_raise(ActiveRecord::PreparedStatementInvalid) { bind '?', 1, 1  }
+    assert_nothing_raised                                { bind '?', 1 }
+    assert_raise(ActiveRecord::PreparedStatementInvalid) { bind '?', 1, 1 }
   end
 
   def test_named_bind_variables
@@ -720,6 +727,12 @@ class FinderTest < ActiveRecord::TestCase
     assert_kind_of Time, Topic.where(["id = :id", { id: 1 }]).first.written_on
   end
 
+  def test_named_bind_arity
+    assert_nothing_raised                                { bind "name = :name", { name: "37signals" } }
+    assert_nothing_raised                                { bind "name = :name", { name: "37signals", id: 1 } }
+    assert_raise(ActiveRecord::PreparedStatementInvalid) { bind "name = :name", { id: 1 } }
+  end
+
   class SimpleEnumerable
     include Enumerable
 
@@ -947,7 +960,6 @@ class FinderTest < ActiveRecord::TestCase
     end
   end
 
-  # http://dev.rubyonrails.org/ticket/6778
   def test_find_ignores_previously_inserted_record
     Post.create!(:title => 'test', :body => 'it out')
     assert_equal [], Post.where(id: nil)
diff --git a/activerecord/test/cases/fixture_set/file_test.rb b/activerecord/test/cases/fixture_set/file_test.rb
index 92efa8aca7..242e7a9bec 100644
--- a/activerecord/test/cases/fixture_set/file_test.rb
+++ b/activerecord/test/cases/fixture_set/file_test.rb
@@ -123,6 +123,18 @@ END
         end
       end
 
+      def test_removes_fixture_config_row
+        File.open(::File.join(FIXTURES_ROOT, 'other_posts.yml')) do |fh|
+          assert_equal(['second_welcome'], fh.each.map { |name, _| name })
+        end
+      end
+
+      def test_extracts_model_class_from_config_row
+        File.open(::File.join(FIXTURES_ROOT, 'other_posts.yml')) do |fh|
+          assert_equal 'Post', fh.model_class
+        end
+      end
+
       private
       def tmp_yaml(name, contents)
         t = Tempfile.new name
diff --git a/activerecord/test/cases/fixtures_test.rb b/activerecord/test/cases/fixtures_test.rb
index 07ec08ccf5..a0eaa66e94 100644
--- a/activerecord/test/cases/fixtures_test.rb
+++ b/activerecord/test/cases/fixtures_test.rb
@@ -7,11 +7,12 @@ require 'models/binary'
 require 'models/book'
 require 'models/bulb'
 require 'models/category'
+require 'models/comment'
 require 'models/company'
 require 'models/computer'
 require 'models/course'
 require 'models/developer'
-require 'models/computer'
+require 'models/doubloon'
 require 'models/joke'
 require 'models/matey'
 require 'models/parrot'
@@ -28,7 +29,7 @@ require 'tempfile'
 
 class FixturesTest < ActiveRecord::TestCase
   self.use_instantiated_fixtures = true
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   # other_topics fixture should not be included here
   fixtures :topics, :developers, :accounts, :tasks, :categories, :funny_jokes, :binaries, :traffic_lights
@@ -216,6 +217,13 @@ class FixturesTest < ActiveRecord::TestCase
     end
   end
 
+  def test_yaml_file_with_invalid_column
+    e = assert_raise(ActiveRecord::Fixture::FixtureError) do
+      ActiveRecord::FixtureSet.create_fixtures(FIXTURES_ROOT + "/naked/yml", "parrots")
+    end
+    assert_equal(%(table "parrots" has no column named "arrr".), e.message)
+  end
+
   def test_omap_fixtures
     assert_nothing_raised do
       fixtures = ActiveRecord::FixtureSet.new(Account.connection, 'categories', Category, FIXTURES_ROOT + "/categories_ordered")
@@ -251,18 +259,19 @@ class FixturesTest < ActiveRecord::TestCase
   def test_fixtures_are_set_up_with_database_env_variable
     db_url_tmp = ENV['DATABASE_URL']
     ENV['DATABASE_URL'] = "sqlite3::memory:"
-    ActiveRecord::Base.stubs(:configurations).returns({})
-    test_case = Class.new(ActiveRecord::TestCase) do
-      fixtures :accounts
+    ActiveRecord::Base.stub(:configurations, {}) do
+      test_case = Class.new(ActiveRecord::TestCase) do
+        fixtures :accounts
 
-      def test_fixtures
-        assert accounts(:signals37)
+        def test_fixtures
+          assert accounts(:signals37)
+        end
       end
-    end
 
-    result = test_case.new(:test_fixtures).run
+      result = test_case.new(:test_fixtures).run
 
-    assert result.passed?, "Expected #{result.name} to pass:\n#{result}"
+      assert result.passed?, "Expected #{result.name} to pass:\n#{result}"
+    end
   ensure
     ENV['DATABASE_URL'] = db_url_tmp
   end
@@ -273,16 +282,16 @@ class HasManyThroughFixture < ActiveSupport::TestCase
     Class.new(ActiveRecord::Base) { define_singleton_method(:name) { name } }
   end
 
-  def test_has_many_through
+  def test_has_many_through_with_default_table_name
     pt = make_model "ParrotTreasure"
     parrot = make_model "Parrot"
     treasure = make_model "Treasure"
 
     pt.table_name = "parrots_treasures"
-    pt.belongs_to :parrot, :class => parrot
-    pt.belongs_to :treasure, :class => treasure
+    pt.belongs_to :parrot, :anonymous_class => parrot
+    pt.belongs_to :treasure, :anonymous_class => treasure
 
-    parrot.has_many :parrot_treasures, :class => pt
+    parrot.has_many :parrot_treasures, :anonymous_class => pt
     parrot.has_many :treasures, :through => :parrot_treasures
 
     parrots = File.join FIXTURES_ROOT, 'parrots'
@@ -292,6 +301,24 @@ class HasManyThroughFixture < ActiveSupport::TestCase
     assert_equal load_has_and_belongs_to_many['parrots_treasures'], rows['parrots_treasures']
   end
 
+  def test_has_many_through_with_renamed_table
+    pt = make_model "ParrotTreasure"
+    parrot = make_model "Parrot"
+    treasure = make_model "Treasure"
+
+    pt.belongs_to :parrot, :anonymous_class => parrot
+    pt.belongs_to :treasure, :anonymous_class => treasure
+
+    parrot.has_many :parrot_treasures, :anonymous_class => pt
+    parrot.has_many :treasures, :through => :parrot_treasures
+
+    parrots = File.join FIXTURES_ROOT, 'parrots'
+
+    fs = ActiveRecord::FixtureSet.new parrot.connection, "parrots", parrot, parrots
+    rows = fs.table_rows
+    assert_equal load_has_and_belongs_to_many['parrots_treasures'], rows['parrot_treasures']
+  end
+
   def load_has_and_belongs_to_many
     parrot = make_model "Parrot"
     parrot.has_and_belongs_to_many :treasures
@@ -309,7 +336,7 @@ if Account.connection.respond_to?(:reset_pk_sequence!)
     fixtures :companies
 
     def setup
-      @instances = [Account.new(:credit_limit => 50), Company.new(:name => 'RoR Consulting')]
+      @instances = [Account.new(:credit_limit => 50), Company.new(:name => 'RoR Consulting'), Course.new(name: 'Test')]
       ActiveRecord::FixtureSet.reset_cache # make sure tables get reinitialized
     end
 
@@ -382,9 +409,11 @@ class FixturesWithoutInstantiationTest < ActiveRecord::TestCase
   end
 
   def test_reloading_fixtures_through_accessor_methods
+    topic = Struct.new(:title)
     assert_equal "The First Topic", topics(:first).title
-    @loaded_fixtures['topics']['first'].expects(:find).returns(stub(:title => "Fresh Topic!"))
-    assert_equal "Fresh Topic!", topics(:first, true).title
+    assert_called(@loaded_fixtures['topics']['first'], :find, returns: topic.new("Fresh Topic!")) do
+      assert_equal "Fresh Topic!", topics(:first, true).title
+    end
   end
 end
 
@@ -401,7 +430,7 @@ end
 
 class TransactionalFixturesTest < ActiveRecord::TestCase
   self.use_instantiated_fixtures = true
-  self.use_transactional_fixtures = true
+  self.use_transactional_tests = true
 
   fixtures :topics
 
@@ -488,12 +517,44 @@ class OverRideFixtureMethodTest < ActiveRecord::TestCase
   end
 end
 
+class FixtureWithSetModelClassTest < ActiveRecord::TestCase
+  fixtures :other_posts, :other_comments
+
+  # Set to false to blow away fixtures cache and ensure our fixtures are loaded
+  # and thus takes into account the +set_model_class+.
+  self.use_transactional_tests = false
+
+  def test_uses_fixture_class_defined_in_yaml
+    assert_kind_of Post, other_posts(:second_welcome)
+  end
+
+  def test_loads_the_associations_to_fixtures_with_set_model_class
+    post = other_posts(:second_welcome)
+    comment = other_comments(:second_greetings)
+    assert_equal [comment], post.comments
+    assert_equal post, comment.post
+  end
+end
+
+class SetFixtureClassPrevailsTest < ActiveRecord::TestCase
+  set_fixture_class bad_posts: Post
+  fixtures :bad_posts
+
+  # Set to false to blow away fixtures cache and ensure our fixtures are loaded
+  # and thus takes into account the +set_model_class+.
+  self.use_transactional_tests = false
+
+  def test_uses_set_fixture_class
+    assert_kind_of Post, bad_posts(:bad_welcome)
+  end
+end
+
 class CheckSetTableNameFixturesTest < ActiveRecord::TestCase
   set_fixture_class :funny_jokes => Joke
   fixtures :funny_jokes
   # Set to false to blow away fixtures cache and ensure our fixtures are loaded
   # and thus takes into account our set_fixture_class
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def test_table_method
     assert_kind_of Joke, funny_jokes(:a_joke)
@@ -505,7 +566,7 @@ class FixtureNameIsNotTableNameFixturesTest < ActiveRecord::TestCase
   fixtures :items
   # Set to false to blow away fixtures cache and ensure our fixtures are loaded
   # and thus takes into account our set_fixture_class
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def test_named_accessor
     assert_kind_of Book, items(:dvd)
@@ -517,7 +578,7 @@ class FixtureNameIsNotTableNameMultipleFixturesTest < ActiveRecord::TestCase
   fixtures :items, :funny_jokes
   # Set to false to blow away fixtures cache and ensure our fixtures are loaded
   # and thus takes into account our set_fixture_class
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def test_named_accessor_of_differently_named_fixture
     assert_kind_of Book, items(:dvd)
@@ -531,7 +592,7 @@ end
 class CustomConnectionFixturesTest < ActiveRecord::TestCase
   set_fixture_class :courses => Course
   fixtures :courses
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def test_leaky_destroy
     assert_nothing_raised { courses(:ruby) }
@@ -546,7 +607,7 @@ end
 class TransactionalFixturesOnCustomConnectionTest < ActiveRecord::TestCase
   set_fixture_class :courses => Course
   fixtures :courses
-  self.use_transactional_fixtures = true
+  self.use_transactional_tests = true
 
   def test_leaky_destroy
     assert_nothing_raised { courses(:ruby) }
@@ -562,7 +623,7 @@ class InvalidTableNameFixturesTest < ActiveRecord::TestCase
   fixtures :funny_jokes
   # Set to false to blow away fixtures cache and ensure our fixtures are loaded
   # and thus takes into account our lack of set_fixture_class
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def test_raises_error
     assert_raise ActiveRecord::FixtureClassNotFound do
@@ -576,7 +637,7 @@ class CheckEscapedYamlFixturesTest < ActiveRecord::TestCase
   fixtures :funny_jokes
   # Set to false to blow away fixtures cache and ensure our fixtures are loaded
   # and thus takes into account our set_fixture_class
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def test_proper_escaped_fixture
     assert_equal "The \\n Aristocrats\nAte the candy\n", funny_jokes(:another_joke).name
@@ -646,7 +707,7 @@ class LoadAllFixturesWithPathnameTest < ActiveRecord::TestCase
 end
 
 class FasterFixturesTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
   fixtures :categories, :authors
 
   def load_extra_fixture(name)
@@ -672,7 +733,8 @@ class FasterFixturesTest < ActiveRecord::TestCase
 end
 
 class FoxyFixturesTest < ActiveRecord::TestCase
-  fixtures :parrots, :parrots_pirates, :pirates, :treasures, :mateys, :ships, :computers, :developers, :"admin/accounts", :"admin/users"
+  fixtures :parrots, :parrots_pirates, :pirates, :treasures, :mateys, :ships, :computers,
+           :developers, :"admin/accounts", :"admin/users", :live_parrots, :dead_parrots, :books
 
   if ActiveRecord::Base.connection.adapter_name == 'PostgreSQL'
     require 'models/uuid_parent'
@@ -812,10 +874,23 @@ class FoxyFixturesTest < ActiveRecord::TestCase
     assert_equal pirates(:blackbeard), parrots(:polly).killer
   end
 
+  def test_supports_sti_with_respective_files
+    assert_kind_of LiveParrot, live_parrots(:dusty)
+    assert_kind_of DeadParrot, dead_parrots(:deadbird)
+    assert_equal pirates(:blackbeard), dead_parrots(:deadbird).killer
+  end
+
   def test_namespaced_models
     assert admin_accounts(:signals37).users.include?(admin_users(:david))
     assert_equal 2, admin_accounts(:signals37).users.size
   end
+
+  def test_resolves_enums
+    assert books(:awdr).published?
+    assert books(:awdr).read?
+    assert books(:rfr).proposed?
+    assert books(:ddd).published?
+  end
 end
 
 class ActiveSupportSubclassWithFixturesTest < ActiveRecord::TestCase
@@ -834,9 +909,9 @@ class CustomNameForFixtureOrModelTest < ActiveRecord::TestCase
   set_fixture_class :randomly_named_a9         =>
                         ClassNameThatDoesNotFollowCONVENTIONS,
                     :'admin/randomly_named_a9' =>
-                        Admin::ClassNameThatDoesNotFollowCONVENTIONS,
+                        Admin::ClassNameThatDoesNotFollowCONVENTIONS1,
                     'admin/randomly_named_b0'  =>
-                        Admin::ClassNameThatDoesNotFollowCONVENTIONS
+                        Admin::ClassNameThatDoesNotFollowCONVENTIONS2
 
   fixtures :randomly_named_a9, 'admin/randomly_named_a9',
            :'admin/randomly_named_b0'
@@ -847,15 +922,15 @@ class CustomNameForFixtureOrModelTest < ActiveRecord::TestCase
   end
 
   def test_named_accessor_for_randomly_named_namespaced_fixture_and_class
-    assert_kind_of Admin::ClassNameThatDoesNotFollowCONVENTIONS,
+    assert_kind_of Admin::ClassNameThatDoesNotFollowCONVENTIONS1,
                    admin_randomly_named_a9(:first_instance)
-    assert_kind_of Admin::ClassNameThatDoesNotFollowCONVENTIONS,
+    assert_kind_of Admin::ClassNameThatDoesNotFollowCONVENTIONS2,
                    admin_randomly_named_b0(:second_instance)
   end
 
   def test_table_name_is_defined_in_the_model
-    assert_equal 'randomly_named_table', ActiveRecord::FixtureSet::all_loaded_fixtures["admin/randomly_named_a9"].table_name
-    assert_equal 'randomly_named_table', Admin::ClassNameThatDoesNotFollowCONVENTIONS.table_name
+    assert_equal 'randomly_named_table2', ActiveRecord::FixtureSet::all_loaded_fixtures["admin/randomly_named_a9"].table_name
+    assert_equal 'randomly_named_table2', Admin::ClassNameThatDoesNotFollowCONVENTIONS1.table_name
   end
 end
 
@@ -871,3 +946,12 @@ class FixturesWithDefaultScopeTest < ActiveRecord::TestCase
     assert_equal "special", bulbs(:special).name
   end
 end
+
+class FixturesWithAbstractBelongsTo < ActiveRecord::TestCase
+  fixtures :pirates, :doubloons
+
+  test "creates fixtures with belongs_to associations defined in abstract base classes" do
+    assert_not_nil doubloons(:blackbeards_doubloon)
+    assert_equal pirates(:blackbeard), doubloons(:blackbeards_doubloon).pirate
+  end
+end
diff --git a/activerecord/test/cases/helper.rb b/activerecord/test/cases/helper.rb
index 0a577fa2f5..d82a3040fc 100644
--- a/activerecord/test/cases/helper.rb
+++ b/activerecord/test/cases/helper.rb
@@ -3,6 +3,7 @@ require File.expand_path('../../../../load_paths', __FILE__)
 require 'config'
 
 require 'active_support/testing/autorun'
+require 'active_support/testing/method_call_assertions'
 require 'stringio'
 
 require 'active_record'
@@ -45,9 +46,8 @@ def in_memory_db?
   ActiveRecord::Base.connection_pool.spec.config[:database] == ":memory:"
 end
 
-def mysql_56?
-  current_adapter?(:Mysql2Adapter) &&
-    ActiveRecord::Base.connection.send(:version).join(".") >= "5.6.0"
+def subsecond_precision_supported?
+  !current_adapter?(:MysqlAdapter, :Mysql2Adapter) || ActiveRecord::Base.connection.version >= '5.6.4'
 end
 
 def mysql_enforcing_gtid_consistency?
@@ -124,7 +124,7 @@ def enable_extension!(extension, connection)
   return connection.reconnect! if connection.extension_enabled?(extension)
 
   connection.enable_extension extension
-  connection.commit_db_transaction
+  connection.commit_db_transaction if connection.transaction_open?
   connection.reconnect!
 end
 
@@ -140,10 +140,11 @@ require "cases/validations_repair_helper"
 class ActiveSupport::TestCase
   include ActiveRecord::TestFixtures
   include ActiveRecord::ValidationsRepairHelper
+  include ActiveSupport::Testing::MethodCallAssertions
 
   self.fixture_path = FIXTURES_ROOT
   self.use_instantiated_fixtures  = false
-  self.use_transactional_fixtures = true
+  self.use_transactional_tests = true
 
   def create_fixtures(*fixture_set_names, &block)
     ActiveRecord::FixtureSet.create_fixtures(ActiveSupport::TestCase.fixture_path, fixture_set_names, fixture_class_names, &block)
@@ -203,8 +204,3 @@ module InTimeZone
 end
 
 require 'mocha/setup' # FIXME: stop using mocha
-
-# FIXME: we have tests that depend on run order, we should fix that and
-# remove this method call.
-require 'active_support/test_case'
-ActiveSupport::TestCase.test_order = :sorted
diff --git a/activerecord/test/cases/hot_compatibility_test.rb b/activerecord/test/cases/hot_compatibility_test.rb
index b4617cf6f9..5ba9a1029a 100644
--- a/activerecord/test/cases/hot_compatibility_test.rb
+++ b/activerecord/test/cases/hot_compatibility_test.rb
@@ -1,7 +1,7 @@
 require 'cases/helper'
 
 class HotCompatibilityTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   setup do
     @klass = Class.new(ActiveRecord::Base) do
diff --git a/activerecord/test/cases/inheritance_test.rb b/activerecord/test/cases/inheritance_test.rb
index fe6323ab02..f67d85603a 100644
--- a/activerecord/test/cases/inheritance_test.rb
+++ b/activerecord/test/cases/inheritance_test.rb
@@ -7,15 +7,32 @@ require 'models/subscriber'
 require 'models/vegetables'
 require 'models/shop'
 
+module InheritanceTestHelper
+  def with_store_full_sti_class(&block)
+    assign_store_full_sti_class true, &block
+  end
+
+  def without_store_full_sti_class(&block)
+    assign_store_full_sti_class false, &block
+  end
+
+  def assign_store_full_sti_class(flag)
+    old_store_full_sti_class = ActiveRecord::Base.store_full_sti_class
+    ActiveRecord::Base.store_full_sti_class = flag
+    yield
+  ensure
+    ActiveRecord::Base.store_full_sti_class = old_store_full_sti_class
+  end
+end
+
 class InheritanceTest < ActiveRecord::TestCase
+  include InheritanceTestHelper
   fixtures :companies, :projects, :subscribers, :accounts, :vegetables
 
   def test_class_with_store_full_sti_class_returns_full_name
-    old = ActiveRecord::Base.store_full_sti_class
-    ActiveRecord::Base.store_full_sti_class = true
-    assert_equal 'Namespaced::Company', Namespaced::Company.sti_name
-  ensure
-    ActiveRecord::Base.store_full_sti_class = old
+    with_store_full_sti_class do
+      assert_equal 'Namespaced::Company', Namespaced::Company.sti_name
+    end
   end
 
   def test_class_with_blank_sti_name
@@ -33,39 +50,31 @@ class InheritanceTest < ActiveRecord::TestCase
   end
 
   def test_class_without_store_full_sti_class_returns_demodulized_name
-    old = ActiveRecord::Base.store_full_sti_class
-    ActiveRecord::Base.store_full_sti_class = false
-    assert_equal 'Company', Namespaced::Company.sti_name
-  ensure
-    ActiveRecord::Base.store_full_sti_class = old
+    without_store_full_sti_class do
+      assert_equal 'Company', Namespaced::Company.sti_name
+    end
   end
 
   def test_should_store_demodulized_class_name_with_store_full_sti_class_option_disabled
-    old = ActiveRecord::Base.store_full_sti_class
-    ActiveRecord::Base.store_full_sti_class = false
-    item = Namespaced::Company.new
-    assert_equal 'Company', item[:type]
-  ensure
-    ActiveRecord::Base.store_full_sti_class = old
+    without_store_full_sti_class do
+      item = Namespaced::Company.new
+      assert_equal 'Company', item[:type]
+    end
   end
 
   def test_should_store_full_class_name_with_store_full_sti_class_option_enabled
-    old = ActiveRecord::Base.store_full_sti_class
-    ActiveRecord::Base.store_full_sti_class = true
-    item = Namespaced::Company.new
-    assert_equal 'Namespaced::Company', item[:type]
-  ensure
-    ActiveRecord::Base.store_full_sti_class = old
+    with_store_full_sti_class do
+      item = Namespaced::Company.new
+      assert_equal 'Namespaced::Company', item[:type]
+    end
   end
 
   def test_different_namespace_subclass_should_load_correctly_with_store_full_sti_class_option
-    old = ActiveRecord::Base.store_full_sti_class
-    ActiveRecord::Base.store_full_sti_class = true
-    item = Namespaced::Company.create :name => "Wolverine 2"
-    assert_not_nil Company.find(item.id)
-    assert_not_nil Namespaced::Company.find(item.id)
-  ensure
-    ActiveRecord::Base.store_full_sti_class = old
+    with_store_full_sti_class do
+      item = Namespaced::Company.create name: "Wolverine 2"
+      assert_not_nil Company.find(item.id)
+      assert_not_nil Namespaced::Company.find(item.id)
+    end
   end
 
   def test_company_descends_from_active_record
@@ -121,6 +130,12 @@ class InheritanceTest < ActiveRecord::TestCase
     assert_kind_of Cabbage, cabbage
   end
 
+  def test_becomes_and_change_tracking_for_inheritance_columns
+    cucumber = Vegetable.find(1)
+    cabbage = cucumber.becomes!(Cabbage)
+    assert_equal ['Cucumber', 'Cabbage'], cabbage.custom_type_change
+  end
+
   def test_alt_becomes_bang_resets_inheritance_type_column
     vegetable = Vegetable.create!(name: "Red Pepper")
     assert_nil vegetable.custom_type
@@ -198,10 +213,28 @@ class InheritanceTest < ActiveRecord::TestCase
     assert_raise(ActiveRecord::SubclassNotFound) { Company.new(:type => 'Account') }
   end
 
+  def test_new_with_unrelated_namespaced_type
+    without_store_full_sti_class do
+      e = assert_raises ActiveRecord::SubclassNotFound do
+        Namespaced::Company.new(type: 'Firm')
+      end
+
+      assert_equal "Invalid single-table inheritance type: Namespaced::Firm is not a subclass of Namespaced::Company", e.message
+    end
+  end
+
+
   def test_new_with_complex_inheritance
     assert_nothing_raised { Client.new(type: 'VerySpecialClient') }
   end
 
+  def test_new_without_storing_full_sti_class
+    without_store_full_sti_class do
+      item = Company.new(type: 'SpecialCo')
+      assert_instance_of Company::SpecialCo, item
+    end
+  end
+
   def test_new_with_autoload_paths
     path = File.expand_path('../../models/autoloadable', __FILE__)
     ActiveSupport::Dependencies.autoload_paths << path
@@ -294,12 +327,12 @@ class InheritanceTest < ActiveRecord::TestCase
 
   def test_eager_load_belongs_to_something_inherited
     account = Account.all.merge!(:includes => :firm).find(1)
-    assert account.association_cache.key?(:firm), "nil proves eager load failed"
+    assert account.association(:firm).loaded?, "association was not eager loaded"
   end
 
   def test_alt_eager_loading
     cabbage = RedCabbage.all.merge!(:includes => :seller).find(4)
-    assert cabbage.association_cache.key?(:seller), "nil proves eager load failed"
+    assert cabbage.association(:seller).loaded?, "association was not eager loaded"
   end
 
   def test_eager_load_belongs_to_primary_key_quoting
@@ -325,6 +358,7 @@ class InheritanceTest < ActiveRecord::TestCase
 end
 
 class InheritanceComputeTypeTest < ActiveRecord::TestCase
+  include InheritanceTestHelper
   fixtures :companies
 
   def setup
@@ -338,27 +372,26 @@ class InheritanceComputeTypeTest < ActiveRecord::TestCase
   end
 
   def test_instantiation_doesnt_try_to_require_corresponding_file
-    ActiveRecord::Base.store_full_sti_class = false
-    foo = Firm.first.clone
-    foo.type = 'FirmOnTheFly'
-    foo.save!
+    without_store_full_sti_class do
+      foo = Firm.first.clone
+      foo.type = 'FirmOnTheFly'
+      foo.save!
 
-    # Should fail without FirmOnTheFly in the type condition.
-    assert_raise(ActiveRecord::RecordNotFound) { Firm.find(foo.id) }
+      # Should fail without FirmOnTheFly in the type condition.
+      assert_raise(ActiveRecord::RecordNotFound) { Firm.find(foo.id) }
 
-    # Nest FirmOnTheFly in the test case where Dependencies won't see it.
-    self.class.const_set :FirmOnTheFly, Class.new(Firm)
-    assert_raise(ActiveRecord::SubclassNotFound) { Firm.find(foo.id) }
+      # Nest FirmOnTheFly in the test case where Dependencies won't see it.
+      self.class.const_set :FirmOnTheFly, Class.new(Firm)
+      assert_raise(ActiveRecord::SubclassNotFound) { Firm.find(foo.id) }
 
-    # Nest FirmOnTheFly in Firm where Dependencies will see it.
-    # This is analogous to nesting models in a migration.
-    Firm.const_set :FirmOnTheFly, Class.new(Firm)
+      # Nest FirmOnTheFly in Firm where Dependencies will see it.
+      # This is analogous to nesting models in a migration.
+      Firm.const_set :FirmOnTheFly, Class.new(Firm)
 
-    # And instantiate will find the existing constant rather than trying
-    # to require firm_on_the_fly.
-    assert_nothing_raised { assert_kind_of Firm::FirmOnTheFly, Firm.find(foo.id) }
-  ensure
-    ActiveRecord::Base.store_full_sti_class = true
+      # And instantiate will find the existing constant rather than trying
+      # to require firm_on_the_fly.
+      assert_nothing_raised { assert_kind_of Firm::FirmOnTheFly, Firm.find(foo.id) }
+    end
   end
 
   def test_sti_type_from_attributes_disabled_in_non_sti_class
diff --git a/activerecord/test/cases/integration_test.rb b/activerecord/test/cases/integration_test.rb
index 0021988083..08a186ae07 100644
--- a/activerecord/test/cases/integration_test.rb
+++ b/activerecord/test/cases/integration_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require 'cases/helper'
 require 'models/company'
@@ -82,7 +81,7 @@ class IntegrationTest < ActiveRecord::TestCase
 
   def test_cache_key_format_for_existing_record_with_updated_at
     dev = Developer.first
-    assert_equal "developers/#{dev.id}-#{dev.updated_at.utc.to_s(:nsec)}", dev.cache_key
+    assert_equal "developers/#{dev.id}-#{dev.updated_at.utc.to_s(:usec)}", dev.cache_key
   end
 
   def test_cache_key_format_for_existing_record_with_updated_at_and_custom_cache_timestamp_format
@@ -97,7 +96,9 @@ class IntegrationTest < ActiveRecord::TestCase
     owner.update_column :updated_at, Time.current
     key = owner.cache_key
 
-    assert pet.touch
+    travel(1.second) do
+      assert pet.touch
+    end
     assert_not_equal key, owner.reload.cache_key
   end
 
@@ -110,30 +111,39 @@ class IntegrationTest < ActiveRecord::TestCase
   def test_cache_key_for_updated_on
     dev = Developer.first
     dev.updated_at = nil
-    assert_equal "developers/#{dev.id}-#{dev.updated_on.utc.to_s(:nsec)}", dev.cache_key
+    assert_equal "developers/#{dev.id}-#{dev.updated_on.utc.to_s(:usec)}", dev.cache_key
   end
 
   def test_cache_key_for_newer_updated_at
     dev = Developer.first
     dev.updated_at += 3600
-    assert_equal "developers/#{dev.id}-#{dev.updated_at.utc.to_s(:nsec)}", dev.cache_key
+    assert_equal "developers/#{dev.id}-#{dev.updated_at.utc.to_s(:usec)}", dev.cache_key
   end
 
   def test_cache_key_for_newer_updated_on
     dev = Developer.first
     dev.updated_on += 3600
-    assert_equal "developers/#{dev.id}-#{dev.updated_on.utc.to_s(:nsec)}", dev.cache_key
+    assert_equal "developers/#{dev.id}-#{dev.updated_on.utc.to_s(:usec)}", dev.cache_key
   end
 
   def test_cache_key_format_is_precise_enough
+    skip("Subsecond precision is not supported") unless subsecond_precision_supported?
     dev = Developer.first
     key = dev.cache_key
     dev.touch
     assert_not_equal key, dev.cache_key
   end
 
+  def test_cache_key_format_is_not_too_precise
+    skip("Subsecond precision is not supported") unless subsecond_precision_supported?
+    dev = Developer.first
+    dev.touch
+    key = dev.cache_key
+    assert_equal key, dev.reload.cache_key
+  end
+
   def test_named_timestamps_for_cache_key
     owner = owners(:blackbeard)
-    assert_equal "owners/#{owner.id}-#{owner.happy_at.utc.to_s(:nsec)}", owner.cache_key(:updated_at, :happy_at)
+    assert_equal "owners/#{owner.id}-#{owner.happy_at.utc.to_s(:usec)}", owner.cache_key(:updated_at, :happy_at)
   end
 end
diff --git a/activerecord/test/cases/invalid_connection_test.rb b/activerecord/test/cases/invalid_connection_test.rb
index 8416c81f45..6523fc29fd 100644
--- a/activerecord/test/cases/invalid_connection_test.rb
+++ b/activerecord/test/cases/invalid_connection_test.rb
@@ -1,7 +1,7 @@
 require "cases/helper"
 
 class TestAdapterWithInvalidConnection < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   class Bird < ActiveRecord::Base
   end
diff --git a/activerecord/test/cases/invertible_migration_test.rb b/activerecord/test/cases/invertible_migration_test.rb
index 8144f3e5c5..84b0ff8fcb 100644
--- a/activerecord/test/cases/invertible_migration_test.rb
+++ b/activerecord/test/cases/invertible_migration_test.rb
@@ -1,5 +1,8 @@
 require "cases/helper"
 
+class Horse < ActiveRecord::Base
+end
+
 module ActiveRecord
   class InvertibleMigrationTest < ActiveRecord::TestCase
     class SilentMigration < ActiveRecord::Migration
@@ -76,6 +79,32 @@ module ActiveRecord
       end
     end
 
+    class ChangeColumnDefault1 < SilentMigration
+      def change
+        create_table("horses") do |t|
+          t.column :name, :string, default: "Sekitoba"
+        end
+      end
+    end
+
+    class ChangeColumnDefault2 < SilentMigration
+      def change
+        change_column_default :horses, :name, from: "Sekitoba", to: "Diomed"
+      end
+    end
+
+    class DisableExtension1 < SilentMigration
+      def change
+        enable_extension "hstore"
+      end
+    end
+
+    class DisableExtension2 < SilentMigration
+      def change
+        disable_extension "hstore"
+      end
+    end
+
     class LegacyMigration < ActiveRecord::Migration
       def self.up
         create_table("horses") do |t|
@@ -144,13 +173,17 @@ module ActiveRecord
     end
 
     def test_exception_on_removing_index_without_column_option
-      RemoveIndexMigration1.new.migrate(:up)
-      migration = RemoveIndexMigration2.new
-      migration.migrate(:up)
+      index_definition = ["horses", [:name, :color]]
+      migration1 = RemoveIndexMigration1.new
+      migration1.migrate(:up)
+      assert migration1.connection.index_exists?(*index_definition)
 
-      assert_raises(IrreversibleMigration) do
-        migration.migrate(:down)
-      end
+      migration2 = RemoveIndexMigration2.new
+      migration2.migrate(:up)
+      assert_not migration2.connection.index_exists?(*index_definition)
+
+      migration2.migrate(:down)
+      assert migration2.connection.index_exists?(*index_definition)
     end
 
     def test_migrate_up
@@ -219,6 +252,42 @@ module ActiveRecord
       assert !revert.connection.table_exists?("horses")
     end
 
+    def test_migrate_revert_change_column_default
+      migration1 = ChangeColumnDefault1.new
+      migration1.migrate(:up)
+      assert_equal "Sekitoba", Horse.new.name
+
+      migration2 = ChangeColumnDefault2.new
+      migration2.migrate(:up)
+      Horse.reset_column_information
+      assert_equal "Diomed", Horse.new.name
+
+      migration2.migrate(:down)
+      Horse.reset_column_information
+      assert_equal "Sekitoba", Horse.new.name
+    end
+
+    if current_adapter?(:PostgreSQLAdapter)
+      def test_migrate_enable_and_disable_extension
+        migration1 = InvertibleMigration.new
+        migration2 = DisableExtension1.new
+        migration3 = DisableExtension2.new
+
+        migration1.migrate(:up)
+        migration2.migrate(:up)
+        assert_equal true, Horse.connection.extension_enabled?('hstore')
+
+        migration3.migrate(:up)
+        assert_equal false, Horse.connection.extension_enabled?('hstore')
+
+        migration3.migrate(:down)
+        assert_equal true, Horse.connection.extension_enabled?('hstore')
+
+        migration2.migrate(:down)
+        assert_equal false, Horse.connection.extension_enabled?('hstore')
+      end
+    end
+
     def test_revert_order
       block = Proc.new{|t| t.string :name }
       recorder = ActiveRecord::Migration::CommandRecorder.new(ActiveRecord::Base.connection)
diff --git a/activerecord/test/cases/locking_test.rb b/activerecord/test/cases/locking_test.rb
index 848174df06..2e1363334d 100644
--- a/activerecord/test/cases/locking_test.rb
+++ b/activerecord/test/cases/locking_test.rb
@@ -177,6 +177,16 @@ class OptimisticLockingTest < ActiveRecord::TestCase
     assert_equal 1, p1.lock_version
   end
 
+  def test_touch_stale_object
+    person = Person.create!(first_name: 'Mehmet Emin')
+    stale_person = Person.find(person.id)
+    person.update_attribute(:gender, 'M')
+
+    assert_raises(ActiveRecord::StaleObjectError) do
+      stale_person.touch
+    end
+  end
+
   def test_lock_column_name_existing
     t1 = LegacyThing.find(1)
     t2 = LegacyThing.find(1)
@@ -260,7 +270,7 @@ class OptimisticLockingTest < ActiveRecord::TestCase
       car.wheels << Wheel.create!
     end
     assert_difference 'car.wheels.count', -1  do
-      car.destroy
+      car.reload.destroy
     end
     assert car.destroyed?
   end
@@ -285,10 +295,10 @@ end
 class OptimisticLockingWithSchemaChangeTest < ActiveRecord::TestCase
   fixtures :people, :legacy_things, :references
 
-  # need to disable transactional fixtures, because otherwise the sqlite3
+  # need to disable transactional tests, because otherwise the sqlite3
   # adapter (at least) chokes when we try and change the schema in the middle
   # of a test (see test_increment_counter_*).
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   { :lock_version => Person, :custom_lock_version => LegacyThing }.each do |name, model|
     define_method("test_increment_counter_updates_#{name}") do
@@ -365,7 +375,7 @@ end
 # (See exec vs. async_exec in the PostgreSQL adapter.)
 unless in_memory_db?
   class PessimisticLockingTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
     fixtures :people, :readers
 
     def setup
diff --git a/activerecord/test/cases/log_subscriber_test.rb b/activerecord/test/cases/log_subscriber_test.rb
index 97c0350911..3846ba8e7f 100644
--- a/activerecord/test/cases/log_subscriber_test.rb
+++ b/activerecord/test/cases/log_subscriber_test.rb
@@ -7,6 +7,20 @@ require "active_support/log_subscriber/test_helper"
 class LogSubscriberTest < ActiveRecord::TestCase
   include ActiveSupport::LogSubscriber::TestHelper
   include ActiveSupport::Logger::Severity
+  REGEXP_CLEAR = Regexp.escape(ActiveRecord::LogSubscriber::CLEAR)
+  REGEXP_BOLD = Regexp.escape(ActiveRecord::LogSubscriber::BOLD)
+  REGEXP_MAGENTA = Regexp.escape(ActiveRecord::LogSubscriber::MAGENTA)
+  REGEXP_CYAN = Regexp.escape(ActiveRecord::LogSubscriber::CYAN)
+  SQL_COLORINGS = {
+      SELECT: Regexp.escape(ActiveRecord::LogSubscriber::BLUE),
+      INSERT: Regexp.escape(ActiveRecord::LogSubscriber::GREEN),
+      UPDATE: Regexp.escape(ActiveRecord::LogSubscriber::YELLOW),
+      DELETE: Regexp.escape(ActiveRecord::LogSubscriber::RED),
+      LOCK: Regexp.escape(ActiveRecord::LogSubscriber::WHITE),
+      ROLLBACK: Regexp.escape(ActiveRecord::LogSubscriber::RED),
+      TRANSACTION: REGEXP_CYAN,
+      OTHER: REGEXP_MAGENTA
+  }
 
   class TestDebugLogSubscriber < ActiveRecord::LogSubscriber
     attr_reader :debugs
@@ -63,14 +77,6 @@ class LogSubscriberTest < ActiveRecord::TestCase
     assert_match(/ruby   rails/, logger.debugs.first)
   end
 
-  def test_ignore_binds_payload_with_nil_column
-    event = Struct.new(:duration, :payload)
-
-    logger = TestDebugLogSubscriber.new
-    logger.sql(event.new(0, sql: 'hi mom!', binds: [[nil, 1]]))
-    assert_equal 1, logger.debugs.length
-  end
-
   def test_basic_query_logging
     Developer.all.load
     wait
@@ -79,6 +85,90 @@ class LogSubscriberTest < ActiveRecord::TestCase
     assert_match(/SELECT .*?FROM .?developers.?/i, @logger.logged(:debug).last)
   end
 
+  def test_basic_query_logging_coloration
+    event = Struct.new(:duration, :payload)
+    logger = TestDebugLogSubscriber.new
+    logger.colorize_logging = true
+    SQL_COLORINGS.each do |verb, color_regex|
+      logger.sql(event.new(0, sql: verb.to_s))
+      assert_match(/#{REGEXP_BOLD}#{color_regex}#{verb}#{REGEXP_CLEAR}/i, logger.debugs.last)
+    end
+  end
+
+  def test_basic_payload_name_logging_coloration_generic_sql
+    event = Struct.new(:duration, :payload)
+    logger = TestDebugLogSubscriber.new
+    logger.colorize_logging = true
+    SQL_COLORINGS.each do |verb, _|
+      logger.sql(event.new(0, sql: verb.to_s))
+      assert_match(/#{REGEXP_BOLD}#{REGEXP_MAGENTA} \(0.0ms\)#{REGEXP_CLEAR}/i, logger.debugs.last)
+
+      logger.sql(event.new(0, {sql: verb.to_s, name: "SQL"}))
+      assert_match(/#{REGEXP_BOLD}#{REGEXP_MAGENTA}SQL \(0.0ms\)#{REGEXP_CLEAR}/i, logger.debugs.last)
+    end
+  end
+
+  def test_basic_payload_name_logging_coloration_named_sql
+    event = Struct.new(:duration, :payload)
+    logger = TestDebugLogSubscriber.new
+    logger.colorize_logging = true
+    SQL_COLORINGS.each do |verb, _|
+      logger.sql(event.new(0, {sql: verb.to_s, name: "Model Load"}))
+      assert_match(/#{REGEXP_BOLD}#{REGEXP_CYAN}Model Load \(0.0ms\)#{REGEXP_CLEAR}/i, logger.debugs.last)
+
+      logger.sql(event.new(0, {sql: verb.to_s, name: "Model Exists"}))
+      assert_match(/#{REGEXP_BOLD}#{REGEXP_CYAN}Model Exists \(0.0ms\)#{REGEXP_CLEAR}/i, logger.debugs.last)
+
+      logger.sql(event.new(0, {sql: verb.to_s, name: "ANY SPECIFIC NAME"}))
+      assert_match(/#{REGEXP_BOLD}#{REGEXP_CYAN}ANY SPECIFIC NAME \(0.0ms\)#{REGEXP_CLEAR}/i, logger.debugs.last)
+    end
+  end
+
+  def test_query_logging_coloration_with_nested_select
+    event = Struct.new(:duration, :payload)
+    logger = TestDebugLogSubscriber.new
+    logger.colorize_logging = true
+    SQL_COLORINGS.slice(:SELECT, :INSERT, :UPDATE, :DELETE).each do |verb, color_regex|
+      logger.sql(event.new(0, sql: "#{verb} WHERE ID IN SELECT"))
+      assert_match(/#{REGEXP_BOLD}#{REGEXP_MAGENTA} \(0.0ms\)#{REGEXP_CLEAR}  #{REGEXP_BOLD}#{color_regex}#{verb} WHERE ID IN SELECT#{REGEXP_CLEAR}/i, logger.debugs.last)
+    end
+  end
+
+  def test_query_logging_coloration_with_multi_line_nested_select
+    event = Struct.new(:duration, :payload)
+    logger = TestDebugLogSubscriber.new
+    logger.colorize_logging = true
+    SQL_COLORINGS.slice(:SELECT, :INSERT, :UPDATE, :DELETE).each do |verb, color_regex|
+      sql = <<-EOS
+        #{verb}
+        WHERE ID IN (
+          SELECT ID FROM THINGS
+        )
+      EOS
+      logger.sql(event.new(0, sql: sql))
+      assert_match(/#{REGEXP_BOLD}#{REGEXP_MAGENTA} \(0.0ms\)#{REGEXP_CLEAR}  #{REGEXP_BOLD}#{color_regex}.*#{verb}.*#{REGEXP_CLEAR}/mi, logger.debugs.last)
+    end
+  end
+
+  def test_query_logging_coloration_with_lock
+    event = Struct.new(:duration, :payload)
+    logger = TestDebugLogSubscriber.new
+    logger.colorize_logging = true
+    sql = <<-EOS
+      SELECT * FROM
+        (SELECT * FROM mytable FOR UPDATE) ss
+      WHERE col1 = 5;
+    EOS
+    logger.sql(event.new(0, sql: sql))
+    assert_match(/#{REGEXP_BOLD}#{REGEXP_MAGENTA} \(0.0ms\)#{REGEXP_CLEAR}  #{REGEXP_BOLD}#{SQL_COLORINGS[:LOCK]}.*FOR UPDATE.*#{REGEXP_CLEAR}/mi, logger.debugs.last)
+
+    sql = <<-EOS
+      LOCK TABLE films IN SHARE MODE;
+    EOS
+    logger.sql(event.new(0, sql: sql))
+    assert_match(/#{REGEXP_BOLD}#{REGEXP_MAGENTA} \(0.0ms\)#{REGEXP_CLEAR}  #{REGEXP_BOLD}#{SQL_COLORINGS[:LOCK]}.*LOCK TABLE.*#{REGEXP_CLEAR}/mi, logger.debugs.last)
+  end
+
   def test_exists_query_logging
     Developer.exists? 1
     wait
diff --git a/activerecord/test/cases/migration/change_schema_test.rb b/activerecord/test/cases/migration/change_schema_test.rb
index b3129a8984..83e50048ec 100644
--- a/activerecord/test/cases/migration/change_schema_test.rb
+++ b/activerecord/test/cases/migration/change_schema_test.rb
@@ -68,8 +68,8 @@ module ActiveRecord
         five = columns.detect { |c| c.name == "five" } unless mysql
 
         assert_equal "hello", one.default
-        assert_equal true, two.type_cast_from_database(two.default)
-        assert_equal false, three.type_cast_from_database(three.default)
+        assert_equal true, connection.lookup_cast_type_from_column(two).deserialize(two.default)
+        assert_equal false, connection.lookup_cast_type_from_column(three).deserialize(three.default)
         assert_equal '1', four.default
         assert_equal "hello", five.default unless mysql
       end
@@ -105,7 +105,7 @@ module ActiveRecord
         eight   = columns.detect { |c| c.name == "eight_int"   }
 
         if current_adapter?(:OracleAdapter)
-          assert_equal 'NUMBER(8)', eight.sql_type
+          assert_equal 'NUMBER(19)', eight.sql_type
         elsif current_adapter?(:SQLite3Adapter)
           assert_equal 'bigint', eight.sql_type
         else
@@ -403,6 +403,17 @@ module ActiveRecord
         end
       end
 
+      def test_drop_table_if_exists
+        connection.create_table(:testings)
+        assert connection.table_exists?(:testings)
+        connection.drop_table(:testings, if_exists: true)
+        assert_not connection.table_exists?(:testings)
+      end
+
+      def test_drop_table_if_exists_nothing_raised
+        assert_nothing_raised { connection.drop_table(:nonexistent, if_exists: true) }
+      end
+
       private
       def testing_table_with_only_foo_attribute
         connection.create_table :testings, :id => false do |t|
@@ -415,7 +426,7 @@ module ActiveRecord
 
     if ActiveRecord::Base.connection.supports_foreign_keys?
       class ChangeSchemaWithDependentObjectsTest < ActiveRecord::TestCase
-        self.use_transactional_fixtures = false
+        self.use_transactional_tests = false
 
         setup do
           @connection = ActiveRecord::Base.connection
@@ -426,7 +437,7 @@ module ActiveRecord
 
         teardown do
           [:wagons, :trains].each do |table|
-            @connection.drop_table(table) if @connection.table_exists?(table)
+            @connection.drop_table table, if_exists: true
           end
         end
 
diff --git a/activerecord/test/cases/migration/change_table_test.rb b/activerecord/test/cases/migration/change_table_test.rb
index 7010af5434..2f9c50141f 100644
--- a/activerecord/test/cases/migration/change_table_test.rb
+++ b/activerecord/test/cases/migration/change_table_test.rb
@@ -1,5 +1,4 @@
 require "cases/migration/helper"
-require "minitest/mock"
 
 module ActiveRecord
   class Migration
@@ -13,7 +12,7 @@ module ActiveRecord
       end
 
       def with_change_table
-        yield ConnectionAdapters::Table.new(:delete_me, @connection)
+        yield ActiveRecord::Base.connection.update_table_definition(:delete_me, @connection)
       end
 
       def test_references_column_type_adds_id
@@ -100,6 +99,13 @@ module ActiveRecord
         end
       end
 
+      def test_primary_key_creates_primary_key_column
+        with_change_table do |t|
+          @connection.expect :add_column, nil, [:delete_me, :id, :primary_key, primary_key: true, first: true]
+          t.primary_key :id, first: true
+        end
+      end
+
       def test_integer_creates_integer_column
         with_change_table do |t|
           @connection.expect :add_column, nil, [:delete_me, :foo, :integer, {}]
@@ -108,6 +114,14 @@ module ActiveRecord
         end
       end
 
+      def test_bigint_creates_bigint_column
+        with_change_table do |t|
+          @connection.expect :add_column, nil, [:delete_me, :foo, :bigint, {}]
+          @connection.expect :add_column, nil, [:delete_me, :bar, :bigint, {}]
+          t.bigint :foo, :bar
+        end
+      end
+
       def test_string_creates_string_column
         with_change_table do |t|
           @connection.expect :add_column, nil, [:delete_me, :foo, :string, {}]
@@ -116,6 +130,24 @@ module ActiveRecord
         end
       end
 
+      if current_adapter?(:PostgreSQLAdapter)
+        def test_json_creates_json_column
+          with_change_table do |t|
+            @connection.expect :add_column, nil, [:delete_me, :foo, :json, {}]
+            @connection.expect :add_column, nil, [:delete_me, :bar, :json, {}]
+            t.json :foo, :bar
+          end
+        end
+
+        def test_xml_creates_xml_column
+          with_change_table do |t|
+            @connection.expect :add_column, nil, [:delete_me, :foo, :xml, {}]
+            @connection.expect :add_column, nil, [:delete_me, :bar, :xml, {}]
+            t.xml :foo, :bar
+          end
+        end
+      end
+
       def test_column_creates_column
         with_change_table do |t|
           @connection.expect :add_column, nil, [:delete_me, :bar, :integer, {}]
diff --git a/activerecord/test/cases/migration/column_attributes_test.rb b/activerecord/test/cases/migration/column_attributes_test.rb
index 763aa88f72..8d8e661aa5 100644
--- a/activerecord/test/cases/migration/column_attributes_test.rb
+++ b/activerecord/test/cases/migration/column_attributes_test.rb
@@ -5,7 +5,7 @@ module ActiveRecord
     class ColumnAttributesTest < ActiveRecord::TestCase
       include ActiveRecord::Migration::TestHelper
 
-      self.use_transactional_fixtures = false
+      self.use_transactional_tests = false
 
       def test_add_column_newline_default
         string = "foo\nbar"
diff --git a/activerecord/test/cases/migration/column_positioning_test.rb b/activerecord/test/cases/migration/column_positioning_test.rb
index 62186e13a5..4637970ce0 100644
--- a/activerecord/test/cases/migration/column_positioning_test.rb
+++ b/activerecord/test/cases/migration/column_positioning_test.rb
@@ -3,7 +3,7 @@ require 'cases/helper'
 module ActiveRecord
   class Migration
     class ColumnPositioningTest < ActiveRecord::TestCase
-      attr_reader :connection, :table_name
+      attr_reader :connection
       alias :conn :connection
 
       def setup
diff --git a/activerecord/test/cases/migration/columns_test.rb b/activerecord/test/cases/migration/columns_test.rb
index e6aa901814..ab3f584350 100644
--- a/activerecord/test/cases/migration/columns_test.rb
+++ b/activerecord/test/cases/migration/columns_test.rb
@@ -5,7 +5,7 @@ module ActiveRecord
     class ColumnsTest < ActiveRecord::TestCase
       include ActiveRecord::Migration::TestHelper
 
-      self.use_transactional_fixtures = false
+      self.use_transactional_tests = false
 
       # FIXME: this is more of an integration test with AR::Base and the
       # schema modifications.  Maybe we should move this?
@@ -65,7 +65,7 @@ module ActiveRecord
       if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
         def test_mysql_rename_column_preserves_auto_increment
           rename_column "test_models", "id", "id_test"
-          assert_equal "auto_increment", connection.columns("test_models").find { |c| c.name == "id_test" }.extra
+          assert connection.columns("test_models").find { |c| c.name == "id_test" }.auto_increment?
           TestModel.reset_column_information
         ensure
           rename_column "test_models", "id_test", "id"
@@ -196,7 +196,7 @@ module ActiveRecord
 
         old_columns = connection.columns(TestModel.table_name)
         assert old_columns.find { |c|
-          default = c.type_cast_from_database(c.default)
+          default = connection.lookup_cast_type_from_column(c).deserialize(c.default)
           c.name == 'approved' && c.type == :boolean && default == true
         }
 
@@ -204,11 +204,11 @@ module ActiveRecord
         new_columns = connection.columns(TestModel.table_name)
 
         assert_not new_columns.find { |c|
-          default = c.type_cast_from_database(c.default)
+          default = connection.lookup_cast_type_from_column(c).deserialize(c.default)
           c.name == 'approved' and c.type == :boolean and default == true
         }
         assert new_columns.find { |c|
-          default = c.type_cast_from_database(c.default)
+          default = connection.lookup_cast_type_from_column(c).deserialize(c.default)
           c.name == 'approved' and c.type == :boolean and default == false
         }
         change_column :test_models, :approved, :boolean, :default => true
@@ -267,6 +267,13 @@ module ActiveRecord
         assert_nil TestModel.new.first_name
       end
 
+      def test_change_column_default_with_from_and_to
+        add_column "test_models", "first_name", :string
+        connection.change_column_default "test_models", "first_name", from: nil, to: "Tester"
+
+        assert_equal "Tester", TestModel.new.first_name
+      end
+
       def test_remove_column_no_second_parameter_raises_exception
         assert_raise(ArgumentError) { connection.remove_column("funny") }
       end
diff --git a/activerecord/test/cases/migration/command_recorder_test.rb b/activerecord/test/cases/migration/command_recorder_test.rb
index 8cba777fe2..1e3529db54 100644
--- a/activerecord/test/cases/migration/command_recorder_test.rb
+++ b/activerecord/test/cases/migration/command_recorder_test.rb
@@ -31,7 +31,8 @@ module ActiveRecord
       end
 
       def test_unknown_commands_delegate
-        recorder = CommandRecorder.new(stub(:foo => 'bar'))
+        recorder = Struct.new(:foo)
+        recorder = CommandRecorder.new(recorder.new('bar'))
         assert_equal 'bar', recorder.foo
       end
 
@@ -169,6 +170,16 @@ module ActiveRecord
         end
       end
 
+      def test_invert_change_column_default_with_from_and_to
+        change = @recorder.inverse_of :change_column_default, [:table, :column, from: "old_value", to: "new_value"]
+        assert_equal [:change_column_default, [:table, :column, from: "new_value", to: "old_value"]], change
+      end
+
+      def test_invert_change_column_default_with_from_and_to_with_boolean
+        change = @recorder.inverse_of :change_column_default, [:table, :column, from: true, to: false]
+        assert_equal [:change_column_default, [:table, :column, from: false, to: true]], change
+      end
+
       def test_invert_change_column_null
         add = @recorder.inverse_of :change_column_null, [:table, :column, true]
         assert_equal [:change_column_null, [:table, :column, false]], add
@@ -206,6 +217,11 @@ module ActiveRecord
       end
 
       def test_invert_remove_index
+        add = @recorder.inverse_of :remove_index, [:table, :one]
+        assert_equal [:add_index, [:table, :one]], add
+      end
+
+      def test_invert_remove_index_with_column
         add = @recorder.inverse_of :remove_index, [:table, {column: [:one, :two], options: true}]
         assert_equal [:add_index, [:table, [:one, :two], options: true]], add
       end
@@ -256,6 +272,11 @@ module ActiveRecord
         assert_equal [:add_reference, [:table, :taggable, { polymorphic: true }], nil], add
       end
 
+      def test_invert_remove_reference_with_index_and_foreign_key
+        add = @recorder.inverse_of :remove_reference, [:table, :taggable, { index: true, foreign_key: true }]
+        assert_equal [:add_reference, [:table, :taggable, { index: true, foreign_key: true }], nil], add
+      end
+
       def test_invert_remove_belongs_to_alias
         add = @recorder.inverse_of :remove_belongs_to, [:table, :user]
         assert_equal [:add_reference, [:table, :user], nil], add
@@ -276,17 +297,42 @@ module ActiveRecord
         assert_equal [:remove_foreign_key, [:dogs, :people]], enable
       end
 
+      def test_invert_remove_foreign_key
+        enable = @recorder.inverse_of :remove_foreign_key, [:dogs, :people]
+        assert_equal [:add_foreign_key, [:dogs, :people]], enable
+      end
+
       def test_invert_add_foreign_key_with_column
         enable = @recorder.inverse_of :add_foreign_key, [:dogs, :people, column: "owner_id"]
         assert_equal [:remove_foreign_key, [:dogs, column: "owner_id"]], enable
       end
 
+      def test_invert_remove_foreign_key_with_column
+        enable = @recorder.inverse_of :remove_foreign_key, [:dogs, :people, column: "owner_id"]
+        assert_equal [:add_foreign_key, [:dogs, :people, column: "owner_id"]], enable
+      end
+
       def test_invert_add_foreign_key_with_column_and_name
         enable = @recorder.inverse_of :add_foreign_key, [:dogs, :people, column: "owner_id", name: "fk"]
         assert_equal [:remove_foreign_key, [:dogs, name: "fk"]], enable
       end
 
-      def test_remove_foreign_key_is_irreversible
+      def test_invert_remove_foreign_key_with_column_and_name
+        enable = @recorder.inverse_of :remove_foreign_key, [:dogs, :people, column: "owner_id", name: "fk"]
+        assert_equal [:add_foreign_key, [:dogs, :people, column: "owner_id", name: "fk"]], enable
+      end
+
+      def test_invert_remove_foreign_key_with_primary_key
+        enable = @recorder.inverse_of :remove_foreign_key, [:dogs, :people, primary_key: "person_id"]
+        assert_equal [:add_foreign_key, [:dogs, :people, primary_key: "person_id"]], enable
+      end
+
+      def test_invert_remove_foreign_key_with_on_delete_on_update
+        enable = @recorder.inverse_of :remove_foreign_key, [:dogs, :people, on_delete: :nullify, on_update: :cascade]
+        assert_equal [:add_foreign_key, [:dogs, :people, on_delete: :nullify, on_update: :cascade]], enable
+      end
+
+      def test_invert_remove_foreign_key_is_irreversible_without_to_table
         assert_raises ActiveRecord::IrreversibleMigration do
           @recorder.inverse_of :remove_foreign_key, [:dogs, column: "owner_id"]
         end
@@ -294,6 +340,10 @@ module ActiveRecord
         assert_raises ActiveRecord::IrreversibleMigration do
           @recorder.inverse_of :remove_foreign_key, [:dogs, name: "fk"]
         end
+
+        assert_raises ActiveRecord::IrreversibleMigration do
+          @recorder.inverse_of :remove_foreign_key, [:dogs]
+        end
       end
     end
   end
diff --git a/activerecord/test/cases/migration/create_join_table_test.rb b/activerecord/test/cases/migration/create_join_table_test.rb
index bea9d6b2c9..8fd08fe4ce 100644
--- a/activerecord/test/cases/migration/create_join_table_test.rb
+++ b/activerecord/test/cases/migration/create_join_table_test.rb
@@ -140,7 +140,7 @@ module ActiveRecord
           tables_after = connection.tables - tables_before
 
           tables_after.each do |table|
-            connection.execute "DROP TABLE #{table}"
+            connection.drop_table table
           end
         end
     end
diff --git a/activerecord/test/cases/migration/foreign_key_test.rb b/activerecord/test/cases/migration/foreign_key_test.rb
index f8b1bf8c9d..72f2fa95f1 100644
--- a/activerecord/test/cases/migration/foreign_key_test.rb
+++ b/activerecord/test/cases/migration/foreign_key_test.rb
@@ -8,6 +8,7 @@ module ActiveRecord
     class ForeignKeyTest < ActiveRecord::TestCase
       include DdlHelper
       include SchemaDumpingHelper
+      include ActiveSupport::Testing::Stream
 
       class Rocket < ActiveRecord::Base
       end
@@ -29,8 +30,8 @@ module ActiveRecord
 
       teardown do
         if defined?(@connection)
-          @connection.drop_table "astronauts" if @connection.table_exists? 'astronauts'
-          @connection.drop_table "rockets" if @connection.table_exists? 'rockets'
+          @connection.drop_table "astronauts", if_exists: true
+          @connection.drop_table "rockets", if_exists: true
         end
       end
 
@@ -57,7 +58,7 @@ module ActiveRecord
         assert_equal "rockets", fk.to_table
         assert_equal "rocket_id", fk.column
         assert_equal "id", fk.primary_key
-        assert_match(/^fk_rails_.{10}$/, fk.name)
+        assert_equal("fk_rails_78146ddd2e", fk.name)
       end
 
       def test_add_foreign_key_with_column
@@ -71,7 +72,7 @@ module ActiveRecord
         assert_equal "rockets", fk.to_table
         assert_equal "rocket_id", fk.column
         assert_equal "id", fk.primary_key
-        assert_match(/^fk_rails_.{10}$/, fk.name)
+        assert_equal("fk_rails_78146ddd2e", fk.name)
       end
 
       def test_add_foreign_key_with_non_standard_primary_key
@@ -146,6 +147,27 @@ module ActiveRecord
         assert_equal :nullify, fk.on_update
       end
 
+      def test_foreign_key_exists
+        @connection.add_foreign_key :astronauts, :rockets
+
+        assert @connection.foreign_key_exists?(:astronauts, :rockets)
+        assert_not @connection.foreign_key_exists?(:astronauts, :stars)
+      end
+
+      def test_foreign_key_exists_by_column
+        @connection.add_foreign_key :astronauts, :rockets, column: "rocket_id"
+
+        assert @connection.foreign_key_exists?(:astronauts, column: "rocket_id")
+        assert_not @connection.foreign_key_exists?(:astronauts, column: "star_id")
+      end
+
+      def test_foreign_key_exists_by_name
+        @connection.add_foreign_key :astronauts, :rockets, column: "rocket_id", name: "fancy_named_fk"
+
+        assert @connection.foreign_key_exists?(:astronauts, name: "fancy_named_fk")
+        assert_not @connection.foreign_key_exists?(:astronauts, name: "other_fancy_named_fk")
+      end
+
       def test_remove_foreign_key_inferes_column
         @connection.add_foreign_key :astronauts, :rockets
 
@@ -221,17 +243,37 @@ module ActiveRecord
         silence_stream($stdout) { migration.migrate(:down) }
       end
 
-      private
+      class CreateSchoolsAndClassesMigration < ActiveRecord::Migration
+        def change
+          create_table(:schools)
 
-      def silence_stream(stream)
-        old_stream = stream.dup
-        stream.reopen(IO::NULL)
-        stream.sync = true
-        yield
+          create_table(:classes) do |t|
+            t.column :school_id, :integer
+          end
+          add_foreign_key :classes, :schools
+        end
+      end
+
+      def test_add_foreign_key_with_prefix
+        ActiveRecord::Base.table_name_prefix = 'p_'
+        migration = CreateSchoolsAndClassesMigration.new
+        silence_stream($stdout) { migration.migrate(:up) }
+        assert_equal 1, @connection.foreign_keys("p_classes").size
+      ensure
+        silence_stream($stdout) { migration.migrate(:down) }
+        ActiveRecord::Base.table_name_prefix = nil
+      end
+
+      def test_add_foreign_key_with_suffix
+        ActiveRecord::Base.table_name_suffix = '_s'
+        migration = CreateSchoolsAndClassesMigration.new
+        silence_stream($stdout) { migration.migrate(:up) }
+        assert_equal 1, @connection.foreign_keys("classes_s").size
       ensure
-        stream.reopen(old_stream)
-        old_stream.close
+        silence_stream($stdout) { migration.migrate(:down) }
+        ActiveRecord::Base.table_name_suffix = nil
       end
+
     end
   end
 end
diff --git a/activerecord/test/cases/migration/helper.rb b/activerecord/test/cases/migration/helper.rb
index 5bc0898f33..ad85684c0b 100644
--- a/activerecord/test/cases/migration/helper.rb
+++ b/activerecord/test/cases/migration/helper.rb
@@ -28,7 +28,7 @@ module ActiveRecord
         super
         TestModel.reset_table_name
         TestModel.reset_sequence_name
-        connection.drop_table :test_models rescue nil
+        connection.drop_table :test_models, if_exists: true
       end
 
       private
diff --git a/activerecord/test/cases/migration/logger_test.rb b/activerecord/test/cases/migration/logger_test.rb
index 319d3e1af3..bf6e684887 100644
--- a/activerecord/test/cases/migration/logger_test.rb
+++ b/activerecord/test/cases/migration/logger_test.rb
@@ -4,7 +4,7 @@ module ActiveRecord
   class Migration
     class LoggerTest < ActiveRecord::TestCase
       # MySQL can't roll back ddl changes
-      self.use_transactional_fixtures = false
+      self.use_transactional_tests = false
 
       Migration = Struct.new(:name, :version) do
         def disable_ddl_transaction; false end
diff --git a/activerecord/test/cases/migration/pending_migrations_test.rb b/activerecord/test/cases/migration/pending_migrations_test.rb
index 7afac83bd2..4f5589f32a 100644
--- a/activerecord/test/cases/migration/pending_migrations_test.rb
+++ b/activerecord/test/cases/migration/pending_migrations_test.rb
@@ -1,5 +1,4 @@
 require 'cases/helper'
-require "minitest/mock"
 
 module ActiveRecord
   class Migration
diff --git a/activerecord/test/cases/migration/postgresql_geometric_types_test.rb b/activerecord/test/cases/migration/postgresql_geometric_types_test.rb
new file mode 100644
index 0000000000..e4772905bb
--- /dev/null
+++ b/activerecord/test/cases/migration/postgresql_geometric_types_test.rb
@@ -0,0 +1,93 @@
+require 'cases/helper'
+
+module ActiveRecord
+  class Migration
+    class PostgreSQLGeometricTypesTest < ActiveRecord::TestCase
+      attr_reader :connection, :table_name
+
+      def setup
+        super
+        @connection = ActiveRecord::Base.connection
+        @table_name = :testings
+      end
+
+      if current_adapter?(:PostgreSQLAdapter)
+        def test_creating_column_with_point_type
+          connection.create_table(table_name) do |t|
+            t.point :foo_point
+          end
+          
+          assert_column_exists(:foo_point)
+          assert_type_correct(:foo_point, :point)
+        end
+
+        def test_creating_column_with_line_type
+          connection.create_table(table_name) do |t|
+            t.line :foo_line
+          end
+          
+          assert_column_exists(:foo_line)
+          assert_type_correct(:foo_line, :line)
+        end
+
+        def test_creating_column_with_lseg_type
+          connection.create_table(table_name) do |t|
+            t.lseg :foo_lseg
+          end
+          
+          assert_column_exists(:foo_lseg)
+          assert_type_correct(:foo_lseg, :lseg)
+        end
+
+        def test_creating_column_with_box_type
+          connection.create_table(table_name) do |t|
+            t.box :foo_box
+          end
+          
+          assert_column_exists(:foo_box)
+          assert_type_correct(:foo_box, :box)
+        end
+
+        def test_creating_column_with_path_type
+          connection.create_table(table_name) do |t|
+            t.path :foo_path
+          end
+          
+          assert_column_exists(:foo_path)
+          assert_type_correct(:foo_path, :path)
+        end
+
+        def test_creating_column_with_polygon_type
+          connection.create_table(table_name) do |t|
+            t.polygon :foo_polygon
+          end
+          
+          assert_column_exists(:foo_polygon)
+          assert_type_correct(:foo_polygon, :polygon)
+        end
+
+        def test_creating_column_with_circle_type
+          connection.create_table(table_name) do |t|
+            t.circle :foo_circle
+          end
+          
+          assert_column_exists(:foo_circle)
+          assert_type_correct(:foo_circle, :circle)
+        end
+      end
+
+      private
+        def assert_column_exists(column_name)
+          columns = connection.columns(table_name)
+          assert columns.map(&:name).include?(column_name.to_s)
+        end
+
+        def assert_type_correct(column_name, type)
+          columns = connection.columns(table_name)
+          column = columns.select{ |c| c.name == column_name.to_s }.first
+          assert_equal type.to_s, column.sql_type
+        end
+
+    end
+  end
+end
\ No newline at end of file
diff --git a/activerecord/test/cases/migration/references_foreign_key_test.rb b/activerecord/test/cases/migration/references_foreign_key_test.rb
index bba8897a0d..84ec657398 100644
--- a/activerecord/test/cases/migration/references_foreign_key_test.rb
+++ b/activerecord/test/cases/migration/references_foreign_key_test.rb
@@ -10,8 +10,8 @@ module ActiveRecord
       end
 
       teardown do
-        @connection.execute("drop table if exists testings")
-        @connection.execute("drop table if exists testing_parents")
+        @connection.drop_table "testings", if_exists: true
+        @connection.drop_table "testing_parents", if_exists: true
       end
 
       test "foreign keys can be created with the table" do
@@ -32,6 +32,14 @@ module ActiveRecord
         assert_equal [], @connection.foreign_keys("testings")
       end
 
+      test "foreign keys can be created in one query" do
+        assert_queries(1) do
+          @connection.create_table :testings do |t|
+            t.references :testing_parent, foreign_key: true
+          end
+        end
+      end
+
       test "options hash can be passed" do
         @connection.change_table :testing_parents do |t|
           t.integer :other_id
@@ -45,6 +53,15 @@ module ActiveRecord
         assert_equal "other_id", fk.primary_key
       end
 
+      test "to_table option can be passed" do
+        @connection.create_table :testings do |t|
+          t.references :parent, foreign_key: { to_table: :testing_parents }
+        end
+        fks = @connection.foreign_keys("testings")
+        assert_equal([["testings", "testing_parents", "parent_id"]],
+                     fks.map {|fk| [fk.from_table, fk.to_table, fk.column] })
+      end
+
       test "foreign keys cannot be added to polymorphic relations when creating the table" do
         @connection.create_table :testings do |t|
           assert_raises(ArgumentError) do
@@ -95,7 +112,59 @@ module ActiveRecord
           end
         end
       end
+
+      test "foreign key column can be removed" do
+        @connection.create_table :testings do |t|
+          t.references :testing_parent, index: true, foreign_key: true
+        end
+
+        assert_difference "@connection.foreign_keys('testings').size", -1 do
+          @connection.remove_reference :testings, :testing_parent, foreign_key: true
+        end
+      end
+
+      test "foreign key methods respect pluralize_table_names" do
+        begin
+          original_pluralize_table_names = ActiveRecord::Base.pluralize_table_names
+          ActiveRecord::Base.pluralize_table_names = false
+          @connection.create_table :testing
+          @connection.change_table :testing_parents do |t|
+            t.references :testing, foreign_key: true
+          end
+
+          fk = @connection.foreign_keys("testing_parents").first
+          assert_equal "testing_parents", fk.from_table
+          assert_equal "testing", fk.to_table
+
+          assert_difference "@connection.foreign_keys('testing_parents').size", -1 do
+            @connection.remove_reference :testing_parents, :testing, foreign_key: true
+          end
+        ensure
+          ActiveRecord::Base.pluralize_table_names = original_pluralize_table_names
+          @connection.drop_table "testing", if_exists: true
+        end
+      end
+    end
+  end
+end
+else
+class ReferencesWithoutForeignKeySupportTest < ActiveRecord::TestCase
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table(:testing_parents, force: true)
+  end
+
+  teardown do
+    @connection.drop_table("testings", if_exists: true)
+    @connection.drop_table("testing_parents", if_exists: true)
+  end
+
+  test "ignores foreign keys defined with the table" do
+    @connection.create_table :testings do |t|
+      t.references :testing_parent, foreign_key: true
     end
+
+    assert_includes @connection.tables, "testings"
   end
 end
 end
diff --git a/activerecord/test/cases/migration/references_statements_test.rb b/activerecord/test/cases/migration/references_statements_test.rb
index 988bd9c89f..f613fd66c3 100644
--- a/activerecord/test/cases/migration/references_statements_test.rb
+++ b/activerecord/test/cases/migration/references_statements_test.rb
@@ -5,7 +5,7 @@ module ActiveRecord
     class ReferencesStatementsTest < ActiveRecord::TestCase
       include ActiveRecord::Migration::TestHelper
 
-      self.use_transactional_fixtures = false
+      self.use_transactional_tests = false
 
       def setup
         super
diff --git a/activerecord/test/cases/migration/rename_table_test.rb b/activerecord/test/cases/migration/rename_table_test.rb
index a018bac43d..6d742d3f2f 100644
--- a/activerecord/test/cases/migration/rename_table_test.rb
+++ b/activerecord/test/cases/migration/rename_table_test.rb
@@ -5,7 +5,7 @@ module ActiveRecord
     class RenameTableTest < ActiveRecord::TestCase
       include ActiveRecord::Migration::TestHelper
 
-      self.use_transactional_fixtures = false
+      self.use_transactional_tests = false
 
       def setup
         super
@@ -86,8 +86,8 @@ module ActiveRecord
           assert connection.table_exists? :felines
         ensure
           disable_extension!('uuid-ossp', connection)
-          connection.drop_table :cats if connection.table_exists? :cats
-          connection.drop_table :felines if connection.table_exists? :felines
+          connection.drop_table :cats, if_exists: true
+          connection.drop_table :felines, if_exists: true
         end
       end
     end
diff --git a/activerecord/test/cases/migration/table_and_index_test.rb b/activerecord/test/cases/migration/table_and_index_test.rb
index 8fd770abd1..24cba84a09 100644
--- a/activerecord/test/cases/migration/table_and_index_test.rb
+++ b/activerecord/test/cases/migration/table_and_index_test.rb
@@ -6,11 +6,11 @@ module ActiveRecord
       def test_add_schema_info_respects_prefix_and_suffix
         conn = ActiveRecord::Base.connection
 
-        conn.drop_table(ActiveRecord::Migrator.schema_migrations_table_name) if conn.table_exists?(ActiveRecord::Migrator.schema_migrations_table_name)
+        conn.drop_table(ActiveRecord::Migrator.schema_migrations_table_name, if_exists: true)
         # Use shorter prefix and suffix as in Oracle database identifier cannot be larger than 30 characters
         ActiveRecord::Base.table_name_prefix = 'p_'
         ActiveRecord::Base.table_name_suffix = '_s'
-        conn.drop_table(ActiveRecord::Migrator.schema_migrations_table_name) if conn.table_exists?(ActiveRecord::Migrator.schema_migrations_table_name)
+        conn.drop_table(ActiveRecord::Migrator.schema_migrations_table_name, if_exists: true)
 
         conn.initialize_schema_migrations_table
 
diff --git a/activerecord/test/cases/migration_test.rb b/activerecord/test/cases/migration_test.rb
index 7c2d3e81d6..10f1c7216f 100644
--- a/activerecord/test/cases/migration_test.rb
+++ b/activerecord/test/cases/migration_test.rb
@@ -14,9 +14,9 @@ require MIGRATIONS_ROOT + "/decimal/1_give_me_big_numbers"
 
 class BigNumber < ActiveRecord::Base
   unless current_adapter?(:PostgreSQLAdapter, :SQLite3Adapter)
-    attribute :value_of_e, Type::Integer.new
+    attribute :value_of_e, :integer
   end
-  attribute :my_house_population, Type::Integer.new
+  attribute :my_house_population, :integer
 end
 
 class Reminder < ActiveRecord::Base; end
@@ -24,7 +24,7 @@ class Reminder < ActiveRecord::Base; end
 class Thing < ActiveRecord::Base; end
 
 class MigrationTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   fixtures :people
 
@@ -75,22 +75,20 @@ class MigrationTest < ActiveRecord::TestCase
 
     ActiveRecord::Migrator.up(migrations_path)
     assert_equal 3, ActiveRecord::Migrator.current_version
-    assert_equal 3, ActiveRecord::Migrator.last_version
     assert_equal false, ActiveRecord::Migrator.needs_migration?
 
     ActiveRecord::Migrator.down(MIGRATIONS_ROOT + "/valid")
     assert_equal 0, ActiveRecord::Migrator.current_version
-    assert_equal 3, ActiveRecord::Migrator.last_version
     assert_equal true, ActiveRecord::Migrator.needs_migration?
 
-    ActiveRecord::SchemaMigration.create!(:version => ActiveRecord::Migrator.last_version)
+    ActiveRecord::SchemaMigration.create!(version: 3)
     assert_equal true, ActiveRecord::Migrator.needs_migration?
   ensure
     ActiveRecord::Migrator.migrations_paths = old_path
   end
 
   def test_migration_detection_without_schema_migration_table
-    ActiveRecord::Base.connection.drop_table('schema_migrations') if ActiveRecord::Base.connection.table_exists?('schema_migrations')
+    ActiveRecord::Base.connection.drop_table 'schema_migrations', if_exists: true
 
     migrations_path = MIGRATIONS_ROOT + "/valid"
     old_path = ActiveRecord::Migrator.migrations_paths
@@ -115,14 +113,10 @@ class MigrationTest < ActiveRecord::TestCase
   end
 
   def test_migration_version
-    ActiveRecord::Migrator.run(:up, MIGRATIONS_ROOT + "/version_check", 20131219224947)
+    assert_nothing_raised { ActiveRecord::Migrator.run(:up, MIGRATIONS_ROOT + "/version_check", 20131219224947) }
   end
 
   def test_create_table_with_force_true_does_not_drop_nonexisting_table
-    if Person.connection.table_exists?(:testings2)
-      Person.connection.drop_table :testings2
-    end
-
     # using a copy as we need the drop_table method to
     # continue to work for the ensure block of the test
     temp_conn = Person.connection.dup
@@ -133,16 +127,12 @@ class MigrationTest < ActiveRecord::TestCase
       t.column :foo, :string
     end
   ensure
-    Person.connection.drop_table :testings2 rescue nil
-  end
-
-  def connection
-    ActiveRecord::Base.connection
+    Person.connection.drop_table :testings2, if_exists: true
   end
 
   def test_migration_instance_has_connection
     migration = Class.new(ActiveRecord::Migration).new
-    assert_equal connection, migration.connection
+    assert_equal ActiveRecord::Base.connection, migration.connection
   end
 
   def test_method_missing_delegates_to_connection
@@ -162,6 +152,7 @@ class MigrationTest < ActiveRecord::TestCase
 
     assert !BigNumber.table_exists?
     GiveMeBigNumbers.up
+    BigNumber.reset_column_information
 
     assert BigNumber.create(
       :bank_balance => 1586.43,
@@ -397,6 +388,7 @@ class MigrationTest < ActiveRecord::TestCase
     Thing.reset_table_name
     Thing.reset_sequence_name
     WeNeedThings.up
+    Thing.reset_column_information
 
     assert Thing.create("content" => "hello world")
     assert_equal "hello world", Thing.first.content
@@ -416,6 +408,7 @@ class MigrationTest < ActiveRecord::TestCase
     ActiveRecord::Base.table_name_suffix = '_suffix'
     Reminder.reset_table_name
     Reminder.reset_sequence_name
+    Reminder.reset_column_information
     WeNeedReminders.up
     assert Reminder.create("content" => "hello world", "remind_at" => Time.now)
     assert_equal "hello world", Reminder.first.content
@@ -427,8 +420,6 @@ class MigrationTest < ActiveRecord::TestCase
   end
 
   def test_create_table_with_binary_column
-    Person.connection.drop_table :binary_testings rescue nil
-
     assert_nothing_raised {
       Person.connection.create_table :binary_testings do |t|
         t.column "data", :binary, :null => false
@@ -440,7 +431,7 @@ class MigrationTest < ActiveRecord::TestCase
 
     assert_nil data_column.default
 
-    Person.connection.drop_table :binary_testings rescue nil
+    Person.connection.drop_table :binary_testings, if_exists: true
   end
 
   unless mysql_enforcing_gtid_consistency?
@@ -511,12 +502,14 @@ class MigrationTest < ActiveRecord::TestCase
   if current_adapter?(:MysqlAdapter, :Mysql2Adapter, :PostgreSQLAdapter)
     def test_out_of_range_limit_should_raise
       Person.connection.drop_table :test_limits rescue nil
-      assert_raise(ActiveRecord::ActiveRecordError, "integer limit didn't raise") do
+      e = assert_raise(ActiveRecord::ActiveRecordError, "integer limit didn't raise") do
         Person.connection.create_table :test_integer_limits, :force => true do |t|
           t.column :bigone, :integer, :limit => 10
         end
       end
 
+      assert_match(/No integer type has byte size 10/, e.message)
+
       unless current_adapter?(:PostgreSQLAdapter)
         assert_raise(ActiveRecord::ActiveRecordError, "text limit didn't raise") do
           Person.connection.create_table :test_text_limits, :force => true do |t|
@@ -718,6 +711,8 @@ if ActiveRecord::Base.connection.supports_bulk_alter?
 end
 
 class CopyMigrationsTest < ActiveRecord::TestCase
+  include ActiveSupport::Testing::Stream
+
   def setup
   end
 
@@ -927,23 +922,4 @@ class CopyMigrationsTest < ActiveRecord::TestCase
     ActiveRecord::Base.logger = old
   end
 
-  private
-
-  def quietly
-    silence_stream(STDOUT) do
-      silence_stream(STDERR) do
-        yield
-      end
-    end
-  end
-
-  def silence_stream(stream)
-    old_stream = stream.dup
-    stream.reopen(IO::NULL)
-    stream.sync = true
-    yield
-  ensure
-    stream.reopen(old_stream)
-    old_stream.close
-  end
 end
diff --git a/activerecord/test/cases/migrator_test.rb b/activerecord/test/cases/migrator_test.rb
index c0daa83e9c..2ff6938e7b 100644
--- a/activerecord/test/cases/migrator_test.rb
+++ b/activerecord/test/cases/migrator_test.rb
@@ -2,7 +2,7 @@ require "cases/helper"
 require "cases/migration/helper"
 
 class MigratorTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   # Use this class to sense if migrations have gone
   # up or down.
@@ -312,7 +312,7 @@ class MigratorTest < ActiveRecord::TestCase
   def test_migrator_db_has_no_schema_migrations_table
     _, migrator = migrator_class(3)
 
-    ActiveRecord::Base.connection.execute("DROP TABLE schema_migrations")
+    ActiveRecord::Base.connection.drop_table "schema_migrations", if_exists: true
     assert_not ActiveRecord::Base.connection.table_exists?('schema_migrations')
     migrator.migrate("valid", 1)
     assert ActiveRecord::Base.connection.table_exists?('schema_migrations')
diff --git a/activerecord/test/cases/mixin_test.rb b/activerecord/test/cases/mixin_test.rb
index 7ddb2bfee1..7ebdcac711 100644
--- a/activerecord/test/cases/mixin_test.rb
+++ b/activerecord/test/cases/mixin_test.rb
@@ -61,8 +61,6 @@ class TouchTest < ActiveRecord::TestCase
 
   # Make sure Mixin.record_timestamps gets reset, even if this test fails,
   # so that other tests do not fail because Mixin.record_timestamps == false
-  rescue Exception => e
-    raise e
   ensure
     Mixin.record_timestamps = true
   end
diff --git a/activerecord/test/cases/modules_test.rb b/activerecord/test/cases/modules_test.rb
index 6f65bf80eb..7f31325f47 100644
--- a/activerecord/test/cases/modules_test.rb
+++ b/activerecord/test/cases/modules_test.rb
@@ -68,8 +68,7 @@ class ModulesTest < ActiveRecord::TestCase
     end
   end
 
-  # need to add an eager loading condition to force the eager loading model into
-  # the old join model, to test that. See http://dev.rubyonrails.org/ticket/9640
+  # An eager loading condition to force the eager loading model into the old join model.
   def test_eager_loading_in_modules
     clients = []
 
diff --git a/activerecord/test/cases/multiparameter_attributes_test.rb b/activerecord/test/cases/multiparameter_attributes_test.rb
index 4aaf6f8b5f..ae18573126 100644
--- a/activerecord/test/cases/multiparameter_attributes_test.rb
+++ b/activerecord/test/cases/multiparameter_attributes_test.rb
@@ -199,6 +199,7 @@ class MultiParameterAttributeTest < ActiveRecord::TestCase
 
   def test_multiparameter_attributes_on_time_with_time_zone_aware_attributes
     with_timezone_config default: :utc, aware_attributes: true, zone: -28800 do
+      Topic.reset_column_information
       attributes = {
         "written_on(1i)" => "2004", "written_on(2i)" => "6", "written_on(3i)" => "24",
         "written_on(4i)" => "16", "written_on(5i)" => "24", "written_on(6i)" => "00"
@@ -209,6 +210,8 @@ class MultiParameterAttributeTest < ActiveRecord::TestCase
       assert_equal Time.utc(2004, 6, 24, 16, 24, 0), topic.written_on.time
       assert_equal Time.zone, topic.written_on.time_zone
     end
+  ensure
+    Topic.reset_column_information
   end
 
   def test_multiparameter_attributes_on_time_with_time_zone_aware_attributes_false
@@ -227,6 +230,7 @@ class MultiParameterAttributeTest < ActiveRecord::TestCase
   def test_multiparameter_attributes_on_time_with_skip_time_zone_conversion_for_attributes
     with_timezone_config default: :utc, aware_attributes: true, zone: -28800 do
       Topic.skip_time_zone_conversion_for_attributes = [:written_on]
+      Topic.reset_column_information
       attributes = {
         "written_on(1i)" => "2004", "written_on(2i)" => "6", "written_on(3i)" => "24",
         "written_on(4i)" => "16", "written_on(5i)" => "24", "written_on(6i)" => "00"
@@ -238,12 +242,14 @@ class MultiParameterAttributeTest < ActiveRecord::TestCase
     end
   ensure
     Topic.skip_time_zone_conversion_for_attributes = []
+    Topic.reset_column_information
   end
 
   # Oracle does not have a TIME datatype.
   unless current_adapter?(:OracleAdapter)
     def test_multiparameter_attributes_on_time_only_column_with_time_zone_aware_attributes_does_not_do_time_zone_conversion
       with_timezone_config default: :utc, aware_attributes: true, zone: -28800 do
+        Topic.reset_column_information
         attributes = {
           "bonus_time(1i)" => "2000", "bonus_time(2i)" => "1", "bonus_time(3i)" => "1",
           "bonus_time(4i)" => "16", "bonus_time(5i)" => "24"
@@ -253,6 +259,8 @@ class MultiParameterAttributeTest < ActiveRecord::TestCase
         assert_equal Time.zone.local(2000, 1, 1, 16, 24, 0), topic.bonus_time
         assert_not topic.bonus_time.utc?
       end
+    ensure
+      Topic.reset_column_information
     end
   end
 
diff --git a/activerecord/test/cases/multiple_db_test.rb b/activerecord/test/cases/multiple_db_test.rb
index 15c60d5562..39cdcf5403 100644
--- a/activerecord/test/cases/multiple_db_test.rb
+++ b/activerecord/test/cases/multiple_db_test.rb
@@ -4,7 +4,7 @@ require 'models/bird'
 require 'models/course'
 
 class MultipleDbTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def setup
     @courses  = create_fixtures("courses") { Course.retrieve_connection }
@@ -93,14 +93,14 @@ class MultipleDbTest < ActiveRecord::TestCase
     assert_not_equal Entrant.arel_engine.connection, Course.arel_engine.connection
   end
 
-  def test_count_on_custom_connection
-    ActiveRecord::Base.remove_connection
-    assert_equal 1, College.count
-  ensure
-    ActiveRecord::Base.establish_connection :arunit
-  end
-
   unless in_memory_db?
+    def test_count_on_custom_connection
+      ActiveRecord::Base.remove_connection
+      assert_equal 1, College.count
+    ensure
+      ActiveRecord::Base.establish_connection :arunit
+    end
+
     def test_associations_should_work_when_model_has_no_connection
       begin
         ActiveRecord::Base.remove_connection
diff --git a/activerecord/test/cases/nested_attributes_test.rb b/activerecord/test/cases/nested_attributes_test.rb
index 5c7e8a65d2..93cb631a04 100644
--- a/activerecord/test/cases/nested_attributes_test.rb
+++ b/activerecord/test/cases/nested_attributes_test.rb
@@ -273,10 +273,11 @@ class TestNestedAttributesOnAHasOneAssociation < ActiveRecord::TestCase
   end
 
   def test_should_modify_an_existing_record_if_there_is_a_matching_composite_id
-    @ship.stubs(:id).returns('ABC1X')
-    @pirate.ship_attributes = { :id => @ship.id, :name => 'Davy Jones Gold Dagger' }
+    @ship.stub(:id, 'ABC1X') do
+      @pirate.ship_attributes = { :id => @ship.id, :name => 'Davy Jones Gold Dagger' }
 
-    assert_equal 'Davy Jones Gold Dagger', @pirate.ship.name
+      assert_equal 'Davy Jones Gold Dagger', @pirate.ship.name
+    end
   end
 
   def test_should_destroy_an_existing_record_if_there_is_a_matching_id_and_destroy_is_truthy
@@ -457,10 +458,11 @@ class TestNestedAttributesOnABelongsToAssociation < ActiveRecord::TestCase
   end
 
   def test_should_modify_an_existing_record_if_there_is_a_matching_composite_id
-    @pirate.stubs(:id).returns('ABC1X')
-    @ship.pirate_attributes = { :id => @pirate.id, :catchphrase => 'Arr' }
+    @pirate.stub(:id, 'ABC1X') do
+      @ship.pirate_attributes = { :id => @pirate.id, :catchphrase => 'Arr' }
 
-    assert_equal 'Arr', @ship.pirate.catchphrase
+      assert_equal 'Arr', @ship.pirate.catchphrase
+    end
   end
 
   def test_should_destroy_an_existing_record_if_there_is_a_matching_id_and_destroy_is_truthy
@@ -638,17 +640,19 @@ module NestedAttributesOnACollectionAssociationTests
   end
 
   def test_should_take_a_hash_with_composite_id_keys_and_assign_the_attributes_to_the_associated_models
-    @child_1.stubs(:id).returns('ABC1X')
-    @child_2.stubs(:id).returns('ABC2X')
-
-    @pirate.attributes = {
-      association_getter => [
-        { :id => @child_1.id, :name => 'Grace OMalley' },
-        { :id => @child_2.id, :name => 'Privateers Greed' }
-      ]
-    }
+    @child_1.stub(:id, 'ABC1X') do
+      @child_2.stub(:id, 'ABC2X') do
 
-    assert_equal ['Grace OMalley', 'Privateers Greed'], [@child_1.name, @child_2.name]
+        @pirate.attributes = {
+          association_getter => [
+            { :id => @child_1.id, :name => 'Grace OMalley' },
+            { :id => @child_2.id, :name => 'Privateers Greed' }
+          ]
+        }
+
+        assert_equal ['Grace OMalley', 'Privateers Greed'], [@child_1.name, @child_2.name]
+      end
+    end
   end
 
   def test_should_raise_RecordNotFound_if_an_id_is_given_but_doesnt_return_a_record
@@ -658,6 +662,16 @@ module NestedAttributesOnACollectionAssociationTests
     assert_equal "Couldn't find #{@child_1.class.name} with ID=1234567890 for Pirate with ID=#{@pirate.id}", exception.message
   end
 
+  def test_should_raise_RecordNotFound_if_an_id_belonging_to_a_different_record_is_given
+    other_pirate = Pirate.create! catchphrase: 'Ahoy!'
+    other_child = other_pirate.send(@association_name).create! name: 'Buccaneers Servant'
+
+    exception = assert_raise ActiveRecord::RecordNotFound do
+      @pirate.attributes = { association_getter => [{ id: other_child.id }] }
+    end
+    assert_equal "Couldn't find #{@child_1.class.name} with ID=#{other_child.id} for Pirate with ID=#{@pirate.id}", exception.message
+  end
+
   def test_should_automatically_build_new_associated_models_for_each_entry_in_a_hash_where_the_id_is_missing
     @pirate.send(@association_name).destroy_all
     @pirate.reload.attributes = {
@@ -943,7 +957,7 @@ class TestNestedAttributesWithNonStandardPrimaryKeys < ActiveRecord::TestCase
 end
 
 class TestHasOneAutosaveAssociationWhichItselfHasAutosaveAssociations < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     @pirate = Pirate.create!(:catchphrase => "My baby takes tha mornin' train!")
@@ -983,7 +997,7 @@ class TestHasOneAutosaveAssociationWhichItselfHasAutosaveAssociations < ActiveRe
 end
 
 class TestHasManyAutosaveAssociationWhichItselfHasAutosaveAssociations < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false unless supports_savepoints?
+  self.use_transactional_tests = false unless supports_savepoints?
 
   def setup
     @ship = Ship.create!(:name => "The good ship Dollypop")
@@ -1037,4 +1051,56 @@ class TestHasManyAutosaveAssociationWhichItselfHasAutosaveAssociations < ActiveR
     ShipPart.create!(:ship => @ship, :name => "Stern")
     assert_no_queries { @ship.valid? }
   end
+
+  test "circular references do not perform unnecessary queries" do
+    ship = Ship.new(name: "The Black Rock")
+    part = ship.parts.build(name: "Stern")
+    ship.treasures.build(looter: part)
+
+    assert_queries 3 do
+      ship.save!
+    end
+  end
+
+  test "nested singular associations are validated" do
+    part = ShipPart.new(name: "Stern", ship_attributes: { name: nil })
+
+    assert_not part.valid?
+    assert_equal ["Ship name can't be blank"], part.errors.full_messages
+  end
+
+  class ProtectedParameters
+    def initialize(hash)
+      @hash = hash
+    end
+
+    def permitted?
+      true
+    end
+
+    def [](key)
+      @hash[key]
+    end
+
+    def to_h
+      @hash
+    end
+  end
+
+  test "strong params style objects can be assigned for singular associations" do
+    params = { name: "Stern", ship_attributes:
+               ProtectedParameters.new(name: "The Black Rock") }
+    part = ShipPart.new(params)
+
+    assert_equal "Stern", part.name
+    assert_equal "The Black Rock", part.ship.name
+  end
+
+  test "strong params style objects can be assigned for collection associations" do
+    params = { trinkets_attributes: ProtectedParameters.new("0" => ProtectedParameters.new(name: "Necklace"), "1" => ProtectedParameters.new(name: "Spoon")) }
+    part = ShipPart.new(params)
+
+    assert_equal "Necklace", part.trinkets[0].name
+    assert_equal "Spoon", part.trinkets[1].name
+  end
 end
diff --git a/activerecord/test/cases/persistence_test.rb b/activerecord/test/cases/persistence_test.rb
index d6816041bc..31686bde3f 100644
--- a/activerecord/test/cases/persistence_test.rb
+++ b/activerecord/test/cases/persistence_test.rb
@@ -17,6 +17,7 @@ require 'models/minivan'
 require 'models/owner'
 require 'models/person'
 require 'models/pet'
+require 'models/ship'
 require 'models/toy'
 require 'rexml/document'
 
@@ -119,13 +120,22 @@ class PersistenceTest < ActiveRecord::TestCase
     assert_equal 59, accounts(:signals37, :reload).credit_limit
   end
 
+  def test_increment_updates_counter_in_db_using_offset
+    a1 = accounts(:signals37)
+    initial_credit = a1.credit_limit
+    a2 = Account.find(accounts(:signals37).id)
+    a1.increment!(:credit_limit)
+    a2.increment!(:credit_limit)
+    assert_equal initial_credit + 2, a1.reload.credit_limit
+  end
+
   def test_destroy_all
     conditions = "author_name = 'Mary'"
     topics_by_mary = Topic.all.merge!(:where => conditions, :order => 'id').to_a
     assert ! topics_by_mary.empty?
 
     assert_difference('Topic.count', -topics_by_mary.size) do
-      destroyed = Topic.destroy_all(conditions).sort_by(&:id)
+      destroyed = Topic.where(conditions).destroy_all.sort_by(&:id)
       assert_equal topics_by_mary, destroyed
       assert destroyed.all?(&:frozen?), "destroyed topics should be frozen"
     end
@@ -356,6 +366,22 @@ class PersistenceTest < ActiveRecord::TestCase
     assert_equal("David", topic_reloaded.author_name)
   end
 
+  def test_update_attribute_does_not_run_sql_if_attribute_is_not_changed
+    klass = Class.new(Topic) do
+      def self.name; 'Topic'; end
+    end
+    topic = klass.create(title: 'Another New Topic')
+    assert_queries(0) do
+      topic.update_attribute(:title, 'Another New Topic')
+    end
+  end
+
+  def test_update_does_not_run_sql_if_record_has_not_changed
+    topic = Topic.create(title: 'Another New Topic')
+    assert_queries(0) { topic.update(title: 'Another New Topic') }
+    assert_queries(0) { topic.update_attributes(title: 'Another New Topic') }
+  end
+
   def test_delete
     topic = Topic.find(1)
     assert_equal topic, topic.delete, 'topic.delete did not return self'
@@ -881,8 +907,35 @@ class PersistenceTest < ActiveRecord::TestCase
     assert_not post.new_record?
   end
 
+  def test_reload_via_querycache
+    ActiveRecord::Base.connection.enable_query_cache!
+    ActiveRecord::Base.connection.clear_query_cache
+    assert ActiveRecord::Base.connection.query_cache_enabled, 'cache should be on'
+    parrot = Parrot.create(:name => 'Shane')
+
+    # populate the cache with the SELECT result
+    found_parrot = Parrot.find(parrot.id)
+    assert_equal parrot.id, found_parrot.id
+
+    # Manually update the 'name' attribute in the DB directly
+    assert_equal 1, ActiveRecord::Base.connection.query_cache.length
+    ActiveRecord::Base.uncached do
+      found_parrot.name = 'Mary'
+      found_parrot.save
+    end
+
+    # Now reload, and verify that it gets the DB version, and not the querycache version
+    found_parrot.reload
+    assert_equal 'Mary', found_parrot.name
+
+    found_parrot = Parrot.find(parrot.id)
+    assert_equal 'Mary', found_parrot.name
+  ensure
+    ActiveRecord::Base.connection.disable_query_cache!
+  end
+
   class SaveTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     def test_save_touch_false
       widget = Class.new(ActiveRecord::Base) do
@@ -908,7 +961,8 @@ class PersistenceTest < ActiveRecord::TestCase
       assert_equal instance.created_at, created_at
       assert_equal instance.updated_at, updated_at
     ensure
-      ActiveRecord::Base.connection.drop_table :widgets
+      ActiveRecord::Base.connection.drop_table widget.table_name
+      widget.reset_column_information
     end
   end
 end
diff --git a/activerecord/test/cases/pooled_connections_test.rb b/activerecord/test/cases/pooled_connections_test.rb
index 287a3f33ea..daa3271777 100644
--- a/activerecord/test/cases/pooled_connections_test.rb
+++ b/activerecord/test/cases/pooled_connections_test.rb
@@ -3,7 +3,7 @@ require "models/project"
 require "timeout"
 
 class PooledConnectionsTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def setup
     @per_test_teardown = []
diff --git a/activerecord/test/cases/primary_keys_test.rb b/activerecord/test/cases/primary_keys_test.rb
index 751eccc015..5e4ba47988 100644
--- a/activerecord/test/cases/primary_keys_test.rb
+++ b/activerecord/test/cases/primary_keys_test.rb
@@ -175,10 +175,24 @@ class PrimaryKeysTest < ActiveRecord::TestCase
     dashboard = Dashboard.first
     assert_equal '2', dashboard.id
   end
+
+  if current_adapter?(:PostgreSQLAdapter)
+    def test_serial_with_quoted_sequence_name
+      column = MixedCaseMonkey.columns_hash[MixedCaseMonkey.primary_key]
+      assert_equal "nextval('\"mixed_case_monkeys_monkeyID_seq\"'::regclass)", column.default_function
+      assert column.serial?
+    end
+
+    def test_serial_with_unquoted_sequence_name
+      column = Topic.columns_hash[Topic.primary_key]
+      assert_equal "nextval('topics_id_seq'::regclass)", column.default_function
+      assert column.serial?
+    end
+  end
 end
 
 class PrimaryKeyWithNoConnectionTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   unless in_memory_db?
     def test_set_primary_key_with_no_connection
@@ -199,7 +213,7 @@ end
 class PrimaryKeyAnyTypeTest < ActiveRecord::TestCase
   include SchemaDumpingHelper
 
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   class Barcode < ActiveRecord::Base
   end
@@ -210,7 +224,7 @@ class PrimaryKeyAnyTypeTest < ActiveRecord::TestCase
   end
 
   teardown do
-    @connection.execute("DROP TABLE IF EXISTS barcodes")
+    @connection.drop_table(:barcodes) if @connection.table_exists? :barcodes
   end
 
   def test_any_type_primary_key
@@ -227,9 +241,36 @@ class PrimaryKeyAnyTypeTest < ActiveRecord::TestCase
   end
 end
 
+class CompositePrimaryKeyTest < ActiveRecord::TestCase
+  include SchemaDumpingHelper
+
+  self.use_transactional_tests = false
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table(:barcodes, primary_key: ["region", "code"], force: true) do |t|
+      t.string :region
+      t.integer :code
+    end
+  end
+
+  def teardown
+    @connection.drop_table(:barcodes, if_exists: true)
+  end
+
+  def test_composite_primary_key
+    assert_equal ["region", "code"], @connection.primary_keys("barcodes")
+  end
+
+  def test_collectly_dump_composite_primary_key
+    schema = dump_table_schema "barcodes"
+    assert_match %r{create_table "barcodes", primary_key: \["region", "code"\]}, schema
+  end
+end
+
 if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
   class PrimaryKeyWithAnsiQuotesTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     def test_primary_key_method_with_ansi_quotes
       con = ActiveRecord::Base.connection
@@ -245,7 +286,7 @@ if current_adapter?(:PostgreSQLAdapter, :MysqlAdapter, :Mysql2Adapter)
   class PrimaryKeyBigSerialTest < ActiveRecord::TestCase
     include SchemaDumpingHelper
 
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     class Widget < ActiveRecord::Base
     end
@@ -260,7 +301,8 @@ if current_adapter?(:PostgreSQLAdapter, :MysqlAdapter, :Mysql2Adapter)
     end
 
     teardown do
-      @connection.execute("DROP TABLE IF EXISTS widgets")
+      @connection.drop_table :widgets, if_exists: true
+      Widget.reset_column_information
     end
 
     test "primary key column type with bigserial" do
@@ -282,5 +324,16 @@ if current_adapter?(:PostgreSQLAdapter, :MysqlAdapter, :Mysql2Adapter)
         assert_match %r{create_table "widgets", id: :bigint}, schema
       end
     end
+
+    if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
+      test "primary key column type with options" do
+        @connection.create_table(:widgets, id: :primary_key, limit: 8, unsigned: true, force: true)
+        column = @connection.columns(:widgets).find { |c| c.name == 'id' }
+        assert column.auto_increment?
+        assert_equal :integer, column.type
+        assert_equal 8, column.limit
+        assert column.unsigned?
+      end
+    end
   end
 end
diff --git a/activerecord/test/cases/query_cache_test.rb b/activerecord/test/cases/query_cache_test.rb
index 744f9edc47..d84653e4c9 100644
--- a/activerecord/test/cases/query_cache_test.rb
+++ b/activerecord/test/cases/query_cache_test.rb
@@ -184,7 +184,7 @@ class QueryCacheTest < ActiveRecord::TestCase
       # Oracle adapter returns count() as Fixnum or Float
       if current_adapter?(:OracleAdapter)
         assert_kind_of Numeric, Task.connection.select_value("SELECT count(*) AS count_all FROM tasks")
-      elsif current_adapter?(:SQLite3Adapter, :Mysql2Adapter)
+      elsif current_adapter?(:SQLite3Adapter, :Mysql2Adapter, :PostgreSQLAdapter)
         # Future versions of the sqlite3 adapter will return numeric
         assert_instance_of Fixnum,
          Task.connection.select_value("SELECT count(*) AS count_all FROM tasks")
@@ -262,61 +262,66 @@ class QueryCacheExpiryTest < ActiveRecord::TestCase
   end
 
   def test_find
-    Task.connection.expects(:clear_query_cache).times(1)
+    assert_called(Task.connection, :clear_query_cache) do
+      assert !Task.connection.query_cache_enabled
+      Task.cache do
+        assert Task.connection.query_cache_enabled
+        Task.find(1)
 
-    assert !Task.connection.query_cache_enabled
-    Task.cache do
-      assert Task.connection.query_cache_enabled
-      Task.find(1)
+        Task.uncached do
+          assert !Task.connection.query_cache_enabled
+          Task.find(1)
+        end
 
-      Task.uncached do
-        assert !Task.connection.query_cache_enabled
-        Task.find(1)
+        assert Task.connection.query_cache_enabled
       end
-
-      assert Task.connection.query_cache_enabled
+      assert !Task.connection.query_cache_enabled
     end
-    assert !Task.connection.query_cache_enabled
   end
 
   def test_update
-    Task.connection.expects(:clear_query_cache).times(2)
-    Task.cache do
-      task = Task.find(1)
-      task.starting = Time.now.utc
-      task.save!
+    assert_called(Task.connection, :clear_query_cache, times: 2) do
+      Task.cache do
+        task = Task.find(1)
+        task.starting = Time.now.utc
+        task.save!
+      end
     end
   end
 
   def test_destroy
-    Task.connection.expects(:clear_query_cache).times(2)
-    Task.cache do
-      Task.find(1).destroy
+    assert_called(Task.connection, :clear_query_cache, times: 2) do
+      Task.cache do
+        Task.find(1).destroy
+      end
     end
   end
 
   def test_insert
-    ActiveRecord::Base.connection.expects(:clear_query_cache).times(2)
-    Task.cache do
-      Task.create!
+    assert_called(ActiveRecord::Base.connection, :clear_query_cache, times: 2) do
+      Task.cache do
+        Task.create!
+      end
     end
   end
 
   def test_cache_is_expired_by_habtm_update
-    ActiveRecord::Base.connection.expects(:clear_query_cache).times(2)
-    ActiveRecord::Base.cache do
-      c = Category.first
-      p = Post.first
-      p.categories << c
+    assert_called(ActiveRecord::Base.connection, :clear_query_cache, times: 2) do
+      ActiveRecord::Base.cache do
+        c = Category.first
+        p = Post.first
+        p.categories << c
+      end
     end
   end
 
   def test_cache_is_expired_by_habtm_delete
-    ActiveRecord::Base.connection.expects(:clear_query_cache).times(2)
-    ActiveRecord::Base.cache do
-      p = Post.find(1)
-      assert p.categories.any?
-      p.categories.delete_all
+    assert_called(ActiveRecord::Base.connection, :clear_query_cache, times: 2) do
+      ActiveRecord::Base.cache do
+        p = Post.find(1)
+        assert p.categories.any?
+        p.categories.delete_all
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/quoting_test.rb b/activerecord/test/cases/quoting_test.rb
index ad09340518..6d91f96bf6 100644
--- a/activerecord/test/cases/quoting_test.rb
+++ b/activerecord/test/cases/quoting_test.rb
@@ -46,28 +46,28 @@ module ActiveRecord
 
       def test_quoted_time_utc
         with_timezone_config default: :utc do
-          t = Time.now
+          t = Time.now.change(usec: 0)
           assert_equal t.getutc.to_s(:db), @quoter.quoted_date(t)
         end
       end
 
       def test_quoted_time_local
         with_timezone_config default: :local do
-          t = Time.now
+          t = Time.now.change(usec: 0)
           assert_equal t.getlocal.to_s(:db), @quoter.quoted_date(t)
         end
       end
 
       def test_quoted_time_crazy
         with_timezone_config default: :asdfasdf do
-          t = Time.now
+          t = Time.now.change(usec: 0)
           assert_equal t.getlocal.to_s(:db), @quoter.quoted_date(t)
         end
       end
 
       def test_quoted_datetime_utc
         with_timezone_config default: :utc do
-          t = DateTime.now
+          t = Time.now.change(usec: 0).to_datetime
           assert_equal t.getutc.to_s(:db), @quoter.quoted_date(t)
         end
       end
@@ -76,7 +76,7 @@ module ActiveRecord
       # DateTime doesn't define getlocal, so make sure it does nothing
       def test_quoted_datetime_local
         with_timezone_config default: :local do
-          t = DateTime.now
+          t = Time.now.change(usec: 0).to_datetime
           assert_equal t.to_s(:db), @quoter.quoted_date(t)
         end
       end
diff --git a/activerecord/test/cases/readonly_test.rb b/activerecord/test/cases/readonly_test.rb
index 1c919f0b57..5f6eb41240 100644
--- a/activerecord/test/cases/readonly_test.rb
+++ b/activerecord/test/cases/readonly_test.rb
@@ -7,6 +7,7 @@ require 'models/computer'
 require 'models/project'
 require 'models/reader'
 require 'models/person'
+require 'models/ship'
 
 class ReadOnlyTest < ActiveRecord::TestCase
   fixtures :authors, :posts, :comments, :developers, :projects, :developers_projects, :people, :readers
diff --git a/activerecord/test/cases/reflection_test.rb b/activerecord/test/cases/reflection_test.rb
index a2252a836f..9c04a41e69 100644
--- a/activerecord/test/cases/reflection_test.rb
+++ b/activerecord/test/cases/reflection_test.rb
@@ -23,6 +23,7 @@ require 'models/chef'
 require 'models/department'
 require 'models/cake_designer'
 require 'models/drink_designer'
+require 'models/recipe'
 
 class ReflectionTest < ActiveRecord::TestCase
   include ActiveRecord::Reflection
@@ -86,18 +87,15 @@ class ReflectionTest < ActiveRecord::TestCase
     assert_equal "attribute_that_doesnt_exist", column.name
     assert_equal nil, column.sql_type
     assert_equal nil, column.type
-    assert_not column.number?
-    assert_not column.text?
-    assert_not column.binary?
   end
 
-  def test_non_existent_columns_are_identity_types
-    column = @first.column_for_attribute("attribute_that_doesnt_exist")
+  def test_non_existent_types_are_identity_types
+    type = @first.type_for_attribute("attribute_that_doesnt_exist")
     object = Object.new
 
-    assert_equal object, column.type_cast_from_database(object)
-    assert_equal object, column.type_cast_from_user(object)
-    assert_equal object, column.type_cast_for_database(object)
+    assert_equal object, type.deserialize(object)
+    assert_equal object, type.cast(object)
+    assert_equal object, type.serialize(object)
   end
 
   def test_reflection_klass_for_nested_class_name
@@ -280,6 +278,22 @@ class ReflectionTest < ActiveRecord::TestCase
     assert_equal 2, @hotel.chefs.size
   end
 
+  def test_scope_chain_of_polymorphic_association_does_not_leak_into_other_hmt_associations
+    hotel = Hotel.create!
+    department = hotel.departments.create!
+    drink = department.chefs.create!(employable: DrinkDesigner.create!)
+    Recipe.create!(chef_id: drink.id, hotel_id: hotel.id)
+
+    expected_sql = capture_sql { hotel.recipes.to_a }
+
+    Hotel.reflect_on_association(:recipes).clear_association_scope_cache
+    hotel.reload
+    hotel.drink_designers.to_a
+    loaded_sql = capture_sql { hotel.recipes.to_a }
+
+    assert_equal expected_sql, loaded_sql
+  end
+
   def test_nested?
     assert !Author.reflect_on_association(:comments).nested?
     assert Author.reflect_on_association(:tags).nested?
@@ -379,12 +393,14 @@ class ReflectionTest < ActiveRecord::TestCase
     product = Struct.new(:table_name, :pluralize_table_names).new('products', true)
 
     reflection = ActiveRecord::Reflection.create(:has_many, :categories, nil, {}, product)
-    reflection.stubs(:klass).returns(category)
-    assert_equal 'categories_products', reflection.join_table
+    reflection.stub(:klass, category) do
+      assert_equal 'categories_products', reflection.join_table
+    end
 
     reflection = ActiveRecord::Reflection.create(:has_many, :products, nil, {}, category)
-    reflection.stubs(:klass).returns(product)
-    assert_equal 'categories_products', reflection.join_table
+    reflection.stub(:klass, product) do
+      assert_equal 'categories_products', reflection.join_table
+    end
   end
 
   def test_join_table_with_common_prefix
@@ -392,12 +408,14 @@ class ReflectionTest < ActiveRecord::TestCase
     product = Struct.new(:table_name, :pluralize_table_names).new('catalog_products', true)
 
     reflection = ActiveRecord::Reflection.create(:has_many, :categories, nil, {}, product)
-    reflection.stubs(:klass).returns(category)
-    assert_equal 'catalog_categories_products', reflection.join_table
+    reflection.stub(:klass, category) do
+      assert_equal 'catalog_categories_products', reflection.join_table
+    end
 
     reflection = ActiveRecord::Reflection.create(:has_many, :products, nil, {}, category)
-    reflection.stubs(:klass).returns(product)
-    assert_equal 'catalog_categories_products', reflection.join_table
+    reflection.stub(:klass, product) do
+      assert_equal 'catalog_categories_products', reflection.join_table
+    end
   end
 
   def test_join_table_with_different_prefix
@@ -405,12 +423,14 @@ class ReflectionTest < ActiveRecord::TestCase
     page = Struct.new(:table_name, :pluralize_table_names).new('content_pages', true)
 
     reflection = ActiveRecord::Reflection.create(:has_many, :categories, nil, {}, page)
-    reflection.stubs(:klass).returns(category)
-    assert_equal 'catalog_categories_content_pages', reflection.join_table
+    reflection.stub(:klass, category) do
+      assert_equal 'catalog_categories_content_pages', reflection.join_table
+    end
 
     reflection = ActiveRecord::Reflection.create(:has_many, :pages, nil, {}, category)
-    reflection.stubs(:klass).returns(page)
-    assert_equal 'catalog_categories_content_pages', reflection.join_table
+    reflection.stub(:klass, page) do
+      assert_equal 'catalog_categories_content_pages', reflection.join_table
+    end
   end
 
   def test_join_table_can_be_overridden
@@ -418,12 +438,14 @@ class ReflectionTest < ActiveRecord::TestCase
     product = Struct.new(:table_name, :pluralize_table_names).new('products', true)
 
     reflection = ActiveRecord::Reflection.create(:has_many, :categories, nil, { :join_table => 'product_categories' }, product)
-    reflection.stubs(:klass).returns(category)
-    assert_equal 'product_categories', reflection.join_table
+    reflection.stub(:klass, category) do
+      assert_equal 'product_categories', reflection.join_table
+    end
 
     reflection = ActiveRecord::Reflection.create(:has_many, :products, nil, { :join_table => 'product_categories' }, category)
-    reflection.stubs(:klass).returns(product)
-    assert_equal 'product_categories', reflection.join_table
+    reflection.stub(:klass, product) do
+      assert_equal 'product_categories', reflection.join_table
+    end
   end
 
   def test_includes_accepts_symbols
diff --git a/activerecord/test/cases/relation/delegation_test.rb b/activerecord/test/cases/relation/delegation_test.rb
index 29c9d0e2af..989f4e1e5d 100644
--- a/activerecord/test/cases/relation/delegation_test.rb
+++ b/activerecord/test/cases/relation/delegation_test.rb
@@ -28,7 +28,7 @@ module ActiveRecord
   module DelegationWhitelistBlacklistTests
     ARRAY_DELEGATES = [
       :+, :-, :|, :&, :[],
-      :all?, :collect, :detect, :each, :each_cons, :each_with_index,
+      :all?, :collect, :compact, :detect, :each, :each_cons, :each_with_index,
       :exclude?, :find_all, :flat_map, :group_by, :include?, :length,
       :map, :none?, :one?, :partition, :reject, :reverse,
       :sample, :second, :sort, :sort_by, :third,
diff --git a/activerecord/test/cases/relation/merging_test.rb b/activerecord/test/cases/relation/merging_test.rb
index eb76ef6328..0a2e874e4f 100644
--- a/activerecord/test/cases/relation/merging_test.rb
+++ b/activerecord/test/cases/relation/merging_test.rb
@@ -82,26 +82,15 @@ class RelationMergingTest < ActiveRecord::TestCase
     left  = Post.where(title: "omg").where(comments_count: 1)
     right = Post.where(title: "wtf").where(title: "bbq")
 
-    expected = [left.bind_values[1]] + right.bind_values
+    expected = [left.bound_attributes[1]] + right.bound_attributes
     merged   = left.merge(right)
 
-    assert_equal expected, merged.bind_values
+    assert_equal expected, merged.bound_attributes
     assert !merged.to_sql.include?("omg")
     assert merged.to_sql.include?("wtf")
     assert merged.to_sql.include?("bbq")
   end
 
-  def test_merging_keeps_lhs_bind_parameters
-    column = Post.columns_hash['id']
-    binds = [[column, 20]]
-
-    right  = Post.where(id: 20)
-    left   = Post.where(id: 10)
-
-    merged = left.merge(right)
-    assert_equal binds, merged.bind_values
-  end
-
   def test_merging_reorders_bind_params
     post  = Post.first
     right = Post.where(id: 1)
diff --git a/activerecord/test/cases/relation/mutation_test.rb b/activerecord/test/cases/relation/mutation_test.rb
index 2443f10269..88d2dd55ab 100644
--- a/activerecord/test/cases/relation/mutation_test.rb
+++ b/activerecord/test/cases/relation/mutation_test.rb
@@ -55,9 +55,10 @@ module ActiveRecord
 
     test '#order! on non-string does not attempt regexp match for references' do
       obj = Object.new
-      obj.expects(:=~).never
-      assert relation.order!(obj)
-      assert_equal [obj], relation.order_values
+      assert_not_called(obj, :=~) do
+        assert relation.order!(obj)
+        assert_equal [obj], relation.order_values
+      end
     end
 
     test '#references!' do
@@ -81,7 +82,7 @@ module ActiveRecord
       assert_equal [], relation.extending_values
     end
 
-    (Relation::SINGLE_VALUE_METHODS - [:from, :lock, :reordering, :reverse_order, :create_with]).each do |method|
+    (Relation::SINGLE_VALUE_METHODS - [:lock, :reordering, :reverse_order, :create_with, :uniq]).each do |method|
       test "##{method}!" do
         assert relation.public_send("#{method}!", :foo).equal?(relation)
         assert_equal :foo, relation.public_send("#{method}_value")
@@ -90,7 +91,7 @@ module ActiveRecord
 
     test '#from!' do
       assert relation.from!('foo').equal?(relation)
-      assert_equal ['foo', nil], relation.from_value
+      assert_equal 'foo', relation.from_clause.value
     end
 
     test '#lock!' do
@@ -136,12 +137,12 @@ module ActiveRecord
     end
 
     test 'test_merge!' do
-      assert relation.merge!(where: :foo).equal?(relation)
-      assert_equal [:foo], relation.where_values
+      assert relation.merge!(select: :foo).equal?(relation)
+      assert_equal [:foo], relation.select_values
     end
 
     test 'merge with a proc' do
-      assert_equal [:foo], relation.merge(-> { where(:foo) }).where_values
+      assert_equal [:foo], relation.merge(-> { select(:foo) }).select_values
     end
 
     test 'none!' do
@@ -153,13 +154,22 @@ module ActiveRecord
     test 'distinct!' do
       relation.distinct! :foo
       assert_equal :foo, relation.distinct_value
-      assert_equal :foo, relation.uniq_value # deprecated access
+
+      assert_deprecated do
+        assert_equal :foo, relation.uniq_value # deprecated access
+      end
     end
 
     test 'uniq! was replaced by distinct!' do
-      relation.uniq! :foo
+      assert_deprecated(/use distinct! instead/) do
+        relation.uniq! :foo
+      end
+
+      assert_deprecated(/use distinct_value instead/) do
+        assert_equal :foo, relation.uniq_value # deprecated access
+      end
+
       assert_equal :foo, relation.distinct_value
-      assert_equal :foo, relation.uniq_value # deprecated access
     end
   end
 end
diff --git a/activerecord/test/cases/relation/or_test.rb b/activerecord/test/cases/relation/or_test.rb
new file mode 100644
index 0000000000..2006fc9611
--- /dev/null
+++ b/activerecord/test/cases/relation/or_test.rb
@@ -0,0 +1,84 @@
+require "cases/helper"
+require 'models/post'
+
+module ActiveRecord
+  class OrTest < ActiveRecord::TestCase
+    fixtures :posts
+
+    def test_or_with_relation
+      expected = Post.where('id = 1 or id = 2').to_a
+      assert_equal expected, Post.where('id = 1').or(Post.where('id = 2')).to_a
+    end
+
+    def test_or_identity
+      expected = Post.where('id = 1').to_a
+      assert_equal expected, Post.where('id = 1').or(Post.where('id = 1')).to_a
+    end
+
+    def test_or_with_null_left
+      expected = Post.where('id = 1').to_a
+      assert_equal expected, Post.none.or(Post.where('id = 1')).to_a
+    end
+
+    def test_or_with_null_right
+      expected = Post.where('id = 1').to_a
+      assert_equal expected, Post.where('id = 1').or(Post.none).to_a
+    end
+
+    def test_or_with_bind_params
+      assert_equal Post.find([1, 2]), Post.where(id: 1).or(Post.where(id: 2)).to_a
+    end
+
+    def test_or_with_null_both
+      expected = Post.none.to_a
+      assert_equal expected, Post.none.or(Post.none).to_a
+    end
+
+    def test_or_without_left_where
+      expected = Post.all
+      assert_equal expected, Post.or(Post.where('id = 1')).to_a
+    end
+
+    def test_or_without_right_where
+      expected = Post.all
+      assert_equal expected, Post.where('id = 1').or(Post.all).to_a
+    end
+
+    def test_or_preserves_other_querying_methods
+      expected = Post.where('id = 1 or id = 2 or id = 3').order('body asc').to_a
+      partial = Post.order('body asc')
+      assert_equal expected, partial.where('id = 1').or(partial.where(:id => [2, 3])).to_a
+      assert_equal expected, Post.order('body asc').where('id = 1').or(Post.order('body asc').where(:id => [2, 3])).to_a
+    end
+
+    def test_or_with_incompatible_relations
+      assert_raises ArgumentError do
+        Post.order('body asc').where('id = 1').or(Post.order('id desc').where(:id => [2, 3])).to_a
+      end
+    end
+
+    def test_or_when_grouping
+      groups = Post.where('id < 10').group('body').select('body, COUNT(*) AS c')
+      expected = groups.having("COUNT(*) > 1 OR body like 'Such%'").to_a.map {|o| [o.body, o.c] }
+      assert_equal expected, groups.having('COUNT(*) > 1').or(groups.having("body like 'Such%'")).to_a.map {|o| [o.body, o.c] }
+    end
+
+    def test_or_with_named_scope
+      expected = Post.where("id = 1 or body LIKE '\%a\%'").to_a
+      assert_equal expected, Post.where('id = 1').or(Post.containing_the_letter_a)
+    end
+
+    def test_or_inside_named_scope
+      expected = Post.where("body LIKE '\%a\%' OR title LIKE ?", "%'%").order('id DESC').to_a
+      assert_equal expected, Post.order(id: :desc).typographically_interesting
+    end
+
+    def test_or_on_loaded_relation
+      expected = Post.where('id = 1 or id = 2').to_a
+      p = Post.where('id = 1')
+      p.load
+      assert_equal p.loaded?, true
+      assert_equal expected, p.or(Post.where('id = 2')).to_a
+    end
+  end
+end
diff --git a/activerecord/test/cases/relation/predicate_builder_test.rb b/activerecord/test/cases/relation/predicate_builder_test.rb
index 0cc081fced..8f62014622 100644
--- a/activerecord/test/cases/relation/predicate_builder_test.rb
+++ b/activerecord/test/cases/relation/predicate_builder_test.rb
@@ -8,7 +8,7 @@ module ActiveRecord
         Arel::Nodes::InfixOperation.new('~', column, Arel.sql(value.source))
       end)
 
-      assert_match %r{["`]topics["`].["`]title["`] ~ rails}i, Topic.where(title: /rails/).to_sql
+      assert_match %r{["`]topics["`]\.["`]title["`] ~ rails}i, Topic.where(title: /rails/).to_sql
     ensure
       Topic.reset_column_information
     end
diff --git a/activerecord/test/cases/relation/record_fetch_warning_test.rb b/activerecord/test/cases/relation/record_fetch_warning_test.rb
new file mode 100644
index 0000000000..62f0a7cc49
--- /dev/null
+++ b/activerecord/test/cases/relation/record_fetch_warning_test.rb
@@ -0,0 +1,28 @@
+require 'cases/helper'
+require 'models/post'
+
+module ActiveRecord
+  class RecordFetchWarningTest < ActiveRecord::TestCase
+    fixtures :posts
+
+    def test_warn_on_records_fetched_greater_than
+      original_logger = ActiveRecord::Base.logger
+      orginal_warn_on_records_fetched_greater_than = ActiveRecord::Base.warn_on_records_fetched_greater_than
+
+      log = StringIO.new
+      ActiveRecord::Base.logger = ActiveSupport::Logger.new(log)
+      ActiveRecord::Base.logger.level = Logger::WARN
+
+      require 'active_record/relation/record_fetch_warning'
+
+      ActiveRecord::Base.warn_on_records_fetched_greater_than = 1
+
+      Post.all.to_a
+
+      assert_match(/Query fetched/, log.string)
+    ensure
+      ActiveRecord::Base.logger = original_logger
+      ActiveRecord::Base.warn_on_records_fetched_greater_than = orginal_warn_on_records_fetched_greater_than
+    end
+  end
+end
diff --git a/activerecord/test/cases/relation/where_chain_test.rb b/activerecord/test/cases/relation/where_chain_test.rb
index 619055f1e7..27bbd80f79 100644
--- a/activerecord/test/cases/relation/where_chain_test.rb
+++ b/activerecord/test/cases/relation/where_chain_test.rb
@@ -11,22 +11,11 @@ module ActiveRecord
       @name = 'title'
     end
 
-    def test_not_eq
+    def test_not_inverts_where_clause
       relation = Post.where.not(title: 'hello')
+      expected_where_clause = Post.where(title: 'hello').where_clause.invert
 
-      assert_equal 1, relation.where_values.length
-
-      value = relation.where_values.first
-      bind  = relation.bind_values.first
-
-      assert_bound_ast value, Post.arel_table[@name], Arel::Nodes::NotEqual
-      assert_equal 'hello', bind.last
-    end
-
-    def test_not_null
-      expected = Post.arel_table[@name].not_eq(nil)
-      relation = Post.where.not(title: nil)
-      assert_equal([expected], relation.where_values)
+      assert_equal expected_where_clause, relation.where_clause
     end
 
     def test_not_with_nil
@@ -35,146 +24,81 @@ module ActiveRecord
       end
     end
 
-    def test_not_in
-      expected = Post.arel_table[@name].not_in(%w[hello goodbye])
-      relation = Post.where.not(title: %w[hello goodbye])
-      assert_equal([expected], relation.where_values)
-    end
-
     def test_association_not_eq
-      expected = Comment.arel_table[@name].not_eq('hello')
+      expected = Arel::Nodes::Grouping.new(Comment.arel_table[@name].not_eq(Arel::Nodes::BindParam.new))
       relation = Post.joins(:comments).where.not(comments: {title: 'hello'})
-      assert_equal(expected.to_sql, relation.where_values.first.to_sql)
+      assert_equal(expected.to_sql, relation.where_clause.ast.to_sql)
     end
 
     def test_not_eq_with_preceding_where
       relation = Post.where(title: 'hello').where.not(title: 'world')
+      expected_where_clause =
+        Post.where(title: 'hello').where_clause +
+        Post.where(title: 'world').where_clause.invert
 
-      value = relation.where_values.first
-      bind  = relation.bind_values.first
-      assert_bound_ast value, Post.arel_table[@name], Arel::Nodes::Equality
-      assert_equal 'hello', bind.last
-
-      value = relation.where_values.last
-      bind  = relation.bind_values.last
-      assert_bound_ast value, Post.arel_table[@name], Arel::Nodes::NotEqual
-      assert_equal 'world', bind.last
+      assert_equal expected_where_clause, relation.where_clause
     end
 
     def test_not_eq_with_succeeding_where
       relation = Post.where.not(title: 'hello').where(title: 'world')
+      expected_where_clause =
+        Post.where(title: 'hello').where_clause.invert +
+        Post.where(title: 'world').where_clause
 
-      value = relation.where_values.first
-      bind  = relation.bind_values.first
-      assert_bound_ast value, Post.arel_table[@name], Arel::Nodes::NotEqual
-      assert_equal 'hello', bind.last
-
-      value = relation.where_values.last
-      bind  = relation.bind_values.last
-      assert_bound_ast value, Post.arel_table[@name], Arel::Nodes::Equality
-      assert_equal 'world', bind.last
-    end
-
-    def test_not_eq_with_string_parameter
-      expected = Arel::Nodes::Not.new("title = 'hello'")
-      relation = Post.where.not("title = 'hello'")
-      assert_equal([expected], relation.where_values)
-    end
-
-    def test_not_eq_with_array_parameter
-      expected = Arel::Nodes::Not.new("title = 'hello'")
-      relation = Post.where.not(['title = ?', 'hello'])
-      assert_equal([expected], relation.where_values)
+      assert_equal expected_where_clause, relation.where_clause
     end
 
     def test_chaining_multiple
       relation = Post.where.not(author_id: [1, 2]).where.not(title: 'ruby on rails')
+      expected_where_clause =
+        Post.where(author_id: [1, 2]).where_clause.invert +
+        Post.where(title: 'ruby on rails').where_clause.invert
 
-      expected = Post.arel_table['author_id'].not_in([1, 2])
-      assert_equal(expected, relation.where_values[0])
-
-      value = relation.where_values[1]
-      bind  = relation.bind_values.first
-
-      assert_bound_ast value, Post.arel_table[@name], Arel::Nodes::NotEqual
-      assert_equal 'ruby on rails', bind.last
+      assert_equal expected_where_clause, relation.where_clause
     end
 
     def test_rewhere_with_one_condition
       relation = Post.where(title: 'hello').where(title: 'world').rewhere(title: 'alone')
+      expected = Post.where(title: 'alone')
 
-      assert_equal 1, relation.where_values.size
-      value = relation.where_values.first
-      bind = relation.bind_values.first
-      assert_bound_ast value, Post.arel_table[@name], Arel::Nodes::Equality
-      assert_equal 'alone', bind.last
+      assert_equal expected.where_clause, relation.where_clause
     end
 
     def test_rewhere_with_multiple_overwriting_conditions
       relation = Post.where(title: 'hello').where(body: 'world').rewhere(title: 'alone', body: 'again')
+      expected = Post.where(title: 'alone', body: 'again')
 
-      assert_equal 2, relation.where_values.size
-
-      value = relation.where_values.first
-      bind = relation.bind_values.first
-      assert_bound_ast value, Post.arel_table['title'], Arel::Nodes::Equality
-      assert_equal 'alone', bind.last
-
-      value = relation.where_values[1]
-      bind = relation.bind_values[1]
-      assert_bound_ast value, Post.arel_table['body'], Arel::Nodes::Equality
-      assert_equal 'again', bind.last
-    end
-
-    def assert_bound_ast value, table, type
-      assert_equal table, value.left
-      assert_kind_of type, value
-      assert_kind_of Arel::Nodes::BindParam, value.right
+      assert_equal expected.where_clause, relation.where_clause
     end
 
     def test_rewhere_with_one_overwriting_condition_and_one_unrelated
       relation = Post.where(title: 'hello').where(body: 'world').rewhere(title: 'alone')
+      expected = Post.where(body: 'world', title: 'alone')
 
-      assert_equal 2, relation.where_values.size
-
-      value = relation.where_values.first
-      bind  = relation.bind_values.first
-
-      assert_bound_ast value, Post.arel_table['body'], Arel::Nodes::Equality
-      assert_equal 'world', bind.last
-
-      value = relation.where_values.second
-      bind  = relation.bind_values.second
-
-      assert_bound_ast value, Post.arel_table['title'], Arel::Nodes::Equality
-      assert_equal 'alone', bind.last
+      assert_equal expected.where_clause, relation.where_clause
     end
 
     def test_rewhere_with_range
       relation = Post.where(comments_count: 1..3).rewhere(comments_count: 3..5)
 
-      assert_equal 1, relation.where_values.size
       assert_equal Post.where(comments_count: 3..5), relation
     end
 
     def test_rewhere_with_infinite_upper_bound_range
       relation = Post.where(comments_count: 1..Float::INFINITY).rewhere(comments_count: 3..5)
 
-      assert_equal 1, relation.where_values.size
       assert_equal Post.where(comments_count: 3..5), relation
     end
 
     def test_rewhere_with_infinite_lower_bound_range
       relation = Post.where(comments_count: -Float::INFINITY..1).rewhere(comments_count: 3..5)
 
-      assert_equal 1, relation.where_values.size
       assert_equal Post.where(comments_count: 3..5), relation
     end
 
     def test_rewhere_with_infinite_range
       relation = Post.where(comments_count: -Float::INFINITY..Float::INFINITY).rewhere(comments_count: 3..5)
 
-      assert_equal 1, relation.where_values.size
       assert_equal Post.where(comments_count: 3..5), relation
     end
   end
diff --git a/activerecord/test/cases/relation/where_clause_test.rb b/activerecord/test/cases/relation/where_clause_test.rb
new file mode 100644
index 0000000000..c20ed94d90
--- /dev/null
+++ b/activerecord/test/cases/relation/where_clause_test.rb
@@ -0,0 +1,182 @@
+require "cases/helper"
+
+class ActiveRecord::Relation
+  class WhereClauseTest < ActiveRecord::TestCase
+    test "+ combines two where clauses" do
+      first_clause = WhereClause.new([table["id"].eq(bind_param)], [["id", 1]])
+      second_clause = WhereClause.new([table["name"].eq(bind_param)], [["name", "Sean"]])
+      combined = WhereClause.new(
+        [table["id"].eq(bind_param), table["name"].eq(bind_param)],
+        [["id", 1], ["name", "Sean"]],
+      )
+
+      assert_equal combined, first_clause + second_clause
+    end
+
+    test "+ is associative, but not commutative" do
+      a = WhereClause.new(["a"], ["bind a"])
+      b = WhereClause.new(["b"], ["bind b"])
+      c = WhereClause.new(["c"], ["bind c"])
+
+      assert_equal a + (b + c), (a + b) + c
+      assert_not_equal a + b, b + a
+    end
+
+    test "an empty where clause is the identity value for +" do
+      clause = WhereClause.new([table["id"].eq(bind_param)], [["id", 1]])
+
+      assert_equal clause, clause + WhereClause.empty
+    end
+
+    test "merge combines two where clauses" do
+      a = WhereClause.new([table["id"].eq(1)], [])
+      b = WhereClause.new([table["name"].eq("Sean")], [])
+      expected = WhereClause.new([table["id"].eq(1), table["name"].eq("Sean")], [])
+
+      assert_equal expected, a.merge(b)
+    end
+
+    test "merge keeps the right side, when two equality clauses reference the same column" do
+      a = WhereClause.new([table["id"].eq(1), table["name"].eq("Sean")], [])
+      b = WhereClause.new([table["name"].eq("Jim")], [])
+      expected = WhereClause.new([table["id"].eq(1), table["name"].eq("Jim")], [])
+
+      assert_equal expected, a.merge(b)
+    end
+
+    test "merge removes bind parameters matching overlapping equality clauses" do
+      a = WhereClause.new(
+        [table["id"].eq(bind_param), table["name"].eq(bind_param)],
+        [attribute("id", 1), attribute("name", "Sean")],
+      )
+      b = WhereClause.new(
+        [table["name"].eq(bind_param)],
+        [attribute("name", "Jim")]
+      )
+      expected = WhereClause.new(
+        [table["id"].eq(bind_param), table["name"].eq(bind_param)],
+        [attribute("id", 1), attribute("name", "Jim")],
+      )
+
+      assert_equal expected, a.merge(b)
+    end
+
+    test "merge allows for columns with the same name from different tables" do
+      skip "This is not possible as of 4.2, and the binds do not yet contain sufficient information for this to happen"
+      # We might be able to change the implementation to remove conflicts by index, rather than column name
+    end
+
+    test "a clause knows if it is empty" do
+      assert WhereClause.empty.empty?
+      assert_not WhereClause.new(["anything"], []).empty?
+    end
+
+    test "invert cannot handle nil" do
+      where_clause = WhereClause.new([nil], [])
+
+      assert_raises ArgumentError do
+        where_clause.invert
+      end
+    end
+
+    test "invert replaces each part of the predicate with its inverse" do
+      random_object = Object.new
+      original = WhereClause.new([
+        table["id"].in([1, 2, 3]),
+        table["id"].eq(1),
+        "sql literal",
+        random_object
+      ], [])
+      expected = WhereClause.new([
+        table["id"].not_in([1, 2, 3]),
+        table["id"].not_eq(1),
+        Arel::Nodes::Not.new(Arel::Nodes::SqlLiteral.new("sql literal")),
+        Arel::Nodes::Not.new(random_object)
+      ], [])
+
+      assert_equal expected, original.invert
+    end
+
+    test "accept removes binary predicates referencing a given column" do
+      where_clause = WhereClause.new([
+        table["id"].in([1, 2, 3]),
+        table["name"].eq(bind_param),
+        table["age"].gteq(bind_param),
+      ], [
+        attribute("name", "Sean"),
+        attribute("age", 30),
+      ])
+      expected = WhereClause.new([table["age"].gteq(bind_param)], [attribute("age", 30)])
+
+      assert_equal expected, where_clause.except("id", "name")
+    end
+
+    test "ast groups its predicates with AND" do
+      predicates = [
+        table["id"].in([1, 2, 3]),
+        table["name"].eq(bind_param),
+      ]
+      where_clause = WhereClause.new(predicates, [])
+      expected = Arel::Nodes::And.new(predicates)
+
+      assert_equal expected, where_clause.ast
+    end
+
+    test "ast wraps any SQL literals in parenthesis" do
+      random_object = Object.new
+      where_clause = WhereClause.new([
+        table["id"].in([1, 2, 3]),
+        "foo = bar",
+        random_object,
+      ], [])
+      expected = Arel::Nodes::And.new([
+        table["id"].in([1, 2, 3]),
+        Arel::Nodes::Grouping.new(Arel.sql("foo = bar")),
+        Arel::Nodes::Grouping.new(random_object),
+      ])
+
+      assert_equal expected, where_clause.ast
+    end
+
+    test "ast removes any empty strings" do
+      where_clause = WhereClause.new([table["id"].in([1, 2, 3])], [])
+      where_clause_with_empty = WhereClause.new([table["id"].in([1, 2, 3]), ''], [])
+
+      assert_equal where_clause.ast, where_clause_with_empty.ast
+    end
+
+    test "or joins the two clauses using OR" do
+      where_clause = WhereClause.new([table["id"].eq(bind_param)], [attribute("id", 1)])
+      other_clause = WhereClause.new([table["name"].eq(bind_param)], [attribute("name", "Sean")])
+      expected_ast =
+        Arel::Nodes::Grouping.new(
+          Arel::Nodes::Or.new(table["id"].eq(bind_param), table["name"].eq(bind_param))
+        )
+      expected_binds = where_clause.binds + other_clause.binds
+
+      assert_equal expected_ast.to_sql, where_clause.or(other_clause).ast.to_sql
+      assert_equal expected_binds, where_clause.or(other_clause).binds
+    end
+
+    test "or returns an empty where clause when either side is empty" do
+      where_clause = WhereClause.new([table["id"].eq(bind_param)], [attribute("id", 1)])
+
+      assert_equal WhereClause.empty, where_clause.or(WhereClause.empty)
+      assert_equal WhereClause.empty, WhereClause.empty.or(where_clause)
+    end
+
+    private
+
+    def table
+      Arel::Table.new("table")
+    end
+
+    def bind_param
+      Arel::Nodes::BindParam.new
+    end
+
+    def attribute(name, value)
+      ActiveRecord::Attribute.with_cast_value(name, value, ActiveRecord::Type::Value.new)
+    end
+  end
+end
diff --git a/activerecord/test/cases/relation/where_test.rb b/activerecord/test/cases/relation/where_test.rb
index b0573579da..bc6378b90e 100644
--- a/activerecord/test/cases/relation/where_test.rb
+++ b/activerecord/test/cases/relation/where_test.rb
@@ -5,6 +5,7 @@ require "models/cake_designer"
 require "models/chef"
 require "models/comment"
 require "models/edge"
+require "models/essay"
 require "models/post"
 require "models/price_estimate"
 require "models/topic"
@@ -13,7 +14,7 @@ require "models/vertex"
 
 module ActiveRecord
   class WhereTest < ActiveRecord::TestCase
-    fixtures :posts, :edges, :authors, :binaries
+    fixtures :posts, :edges, :authors, :binaries, :essays
 
     def test_where_copies_bind_params
       author = authors(:david)
@@ -28,6 +29,14 @@ module ActiveRecord
       }
     end
 
+    def test_where_copies_bind_params_in_the_right_order
+      author = authors(:david)
+      posts = author.posts.where.not(id: 1)
+      joined = Post.where(id: posts, title: posts.first.title)
+
+      assert_equal joined, [posts.first]
+    end
+
     def test_where_copies_arel_bind_params
       chef = Chef.create!
       CakeDesigner.create!(chef: chef)
@@ -232,5 +241,70 @@ module ActiveRecord
       count = Binary.where(:data => 0).count
       assert_equal 0, count
     end
+
+    def test_where_on_association_with_custom_primary_key
+      author = authors(:david)
+      essay = Essay.where(writer: author).first
+
+      assert_equal essays(:david_modest_proposal), essay
+    end
+
+    def test_where_on_association_with_custom_primary_key_with_relation
+      author = authors(:david)
+      essay = Essay.where(writer: Author.where(id: author.id)).first
+
+      assert_equal essays(:david_modest_proposal), essay
+    end
+
+    def test_where_on_association_with_relation_performs_subselect_not_two_queries
+      author = authors(:david)
+
+      assert_queries(1) do
+        Essay.where(writer: Author.where(id: author.id)).to_a
+      end
+    end
+
+    def test_where_on_association_with_custom_primary_key_with_array_of_base
+      author = authors(:david)
+      essay = Essay.where(writer: [author]).first
+
+      assert_equal essays(:david_modest_proposal), essay
+    end
+
+    def test_where_on_association_with_custom_primary_key_with_array_of_ids
+      essay = Essay.where(writer: ["David"]).first
+
+      assert_equal essays(:david_modest_proposal), essay
+    end
+
+    def test_where_with_strong_parameters
+      protected_params = Class.new do
+        attr_reader :permitted
+        alias :permitted? :permitted
+
+        def initialize(parameters)
+          @parameters = parameters
+          @permitted = false
+        end
+
+        def to_h
+          @parameters
+        end
+
+        def permit!
+          @permitted = true
+          self
+        end
+      end
+
+      author = authors(:david)
+      params = protected_params.new(name: author.name)
+      assert_raises(ActiveModel::ForbiddenAttributesError) { Author.where(params) }
+      assert_equal author, Author.where(params.permit!).first
+    end
+
+    def test_where_with_unsupported_arguments
+      assert_raises(ArgumentError) { Author.where(42) }
+    end
   end
 end
diff --git a/activerecord/test/cases/relation_test.rb b/activerecord/test/cases/relation_test.rb
index f7cb471984..675149556f 100644
--- a/activerecord/test/cases/relation_test.rb
+++ b/activerecord/test/cases/relation_test.rb
@@ -57,9 +57,6 @@ module ActiveRecord
     def test_empty_where_values_hash
       relation = Relation.new(FakeKlass, :b, nil)
       assert_equal({}, relation.where_values_hash)
-
-      relation.where! :hello
-      assert_equal({}, relation.where_values_hash)
     end
 
     def test_has_values
@@ -153,38 +150,48 @@ module ActiveRecord
     end
 
     test 'merging a hash into a relation' do
-      relation = Relation.new(FakeKlass, :b, nil)
-      relation = relation.merge where: :lol, readonly: true
+      relation = Relation.new(Post, Post.arel_table, Post.predicate_builder)
+      relation = relation.merge where: {name: :lol}, readonly: true
 
-      assert_equal [:lol], relation.where_values
+      assert_equal({"name"=>:lol}, relation.where_clause.to_h)
       assert_equal true, relation.readonly_value
     end
 
     test 'merging an empty hash into a relation' do
-      assert_equal [], Relation.new(FakeKlass, :b, nil).merge({}).where_values
+      assert_equal Relation::WhereClause.empty, Relation.new(FakeKlass, :b, nil).merge({}).where_clause
     end
 
     test 'merging a hash with unknown keys raises' do
       assert_raises(ArgumentError) { Relation::HashMerger.new(nil, omg: 'lol') }
     end
 
+    test 'merging nil or false raises' do
+      relation = Relation.new(FakeKlass, :b, nil)
+
+      e = assert_raises(ArgumentError) do
+        relation = relation.merge nil
+      end
+
+      assert_equal 'invalid argument: nil.', e.message
+
+      e = assert_raises(ArgumentError) do
+        relation = relation.merge false
+      end
+
+      assert_equal 'invalid argument: false.', e.message
+    end
+
     test '#values returns a dup of the values' do
-      relation = Relation.new(FakeKlass, :b, nil).where! :foo
+      relation = Relation.new(Post, Post.arel_table, Post.predicate_builder).where!(name: :foo)
       values   = relation.values
 
       values[:where] = nil
-      assert_not_nil relation.where_values
+      assert_not_nil relation.where_clause
     end
 
     test 'relations can be created with a values hash' do
-      relation = Relation.new(FakeKlass, :b, nil, where: [:foo])
-      assert_equal [:foo], relation.where_values
-    end
-
-    test 'merging a single where value' do
-      relation = Relation.new(FakeKlass, :b, nil)
-      relation.merge!(where: :foo)
-      assert_equal [:foo], relation.where_values
+      relation = Relation.new(FakeKlass, :b, nil, select: [:foo])
+      assert_equal [:foo], relation.select_values
     end
 
     test 'merging a hash interpolates conditions' do
@@ -197,7 +204,7 @@ module ActiveRecord
 
       relation = Relation.new(klass, :b, nil)
       relation.merge!(where: ['foo = ?', 'bar'])
-      assert_equal ['foo = bar'], relation.where_values
+      assert_equal Relation::WhereClause.new(['foo = bar'], []), relation.where_clause
     end
 
     def test_merging_readonly_false
@@ -232,6 +239,24 @@ module ActiveRecord
       assert_equal false, post.respond_to?(:title), "post should not respond_to?(:body) since invoking it raises exception"
     end
 
+    def test_select_quotes_when_using_from_clause
+      skip_if_sqlite3_version_includes_quoting_bug
+      quoted_join = ActiveRecord::Base.connection.quote_table_name("join")
+      selected = Post.select(:join).from(Post.select("id as #{quoted_join}")).map(&:join)
+      assert_equal Post.pluck(:id), selected
+    end
+
+    def test_selecting_aliased_attribute_quotes_column_name_when_from_is_used
+      skip_if_sqlite3_version_includes_quoting_bug
+      klass = Class.new(ActiveRecord::Base) do
+        self.table_name = :test_with_keyword_column_name
+        alias_attribute :description, :desc
+      end
+      klass.create!(description: "foo")
+
+      assert_equal ["foo"], klass.select(:description).from(klass.all).map(&:desc)
+    end
+
     def test_relation_merging_with_merged_joins_as_strings
       join_string = "LEFT OUTER JOIN #{Rating.quoted_table_name} ON #{SpecialComment.quoted_table_name}.id = #{Rating.quoted_table_name}.comment_id"
       special_comments_with_ratings = SpecialComment.joins join_string
@@ -244,12 +269,12 @@ module ActiveRecord
         :string
       end
 
-      def type_cast_from_database(value)
+      def deserialize(value)
         raise value unless value == "type cast for database"
         "type cast from database"
       end
 
-      def type_cast_for_database(value)
+      def serialize(value)
         raise value unless value == "value from user"
         "type cast for database"
       end
@@ -266,5 +291,26 @@ module ActiveRecord
 
       assert_equal "type cast from database", UpdateAllTestModel.first.body
     end
+
+    private
+
+    def skip_if_sqlite3_version_includes_quoting_bug
+      if sqlite3_version_includes_quoting_bug?
+        skip <<-ERROR.squish
+          You are using an outdated version of SQLite3 which has a bug in
+          quoted column names. Please update SQLite3 and rebuild the sqlite3
+          ruby gem
+        ERROR
+      end
+    end
+
+    def sqlite3_version_includes_quoting_bug?
+      if current_adapter?(:SQLite3Adapter)
+        selected_quoted_column_names = ActiveRecord::Base.connection.exec_query(
+          'SELECT "join" FROM (SELECT id AS "join" FROM posts) subquery'
+        ).columns
+        ["join"] != selected_quoted_column_names
+      end
+    end
   end
 end
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 9631ea79be..7521f0573a 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -16,7 +16,8 @@ require 'models/engine'
 require 'models/tyre'
 require 'models/minivan'
 require 'models/aircraft'
-
+require "models/possession"
+require "models/reader"
 
 class RelationTest < ActiveRecord::TestCase
   fixtures :authors, :topics, :entrants, :developers, :companies, :developers_projects, :accounts, :categories, :categorizations, :posts, :comments,
@@ -39,15 +40,6 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal van, Minivan.where(:minivan_id => [van]).to_a.first
   end
 
-  def test_bind_values
-    relation = Post.all
-    assert_equal [], relation.bind_values
-
-    relation2 = relation.bind 'foo'
-    assert_equal %w{ foo }, relation2.bind_values
-    assert_equal [], relation.bind_values
-  end
-
   def test_two_scopes_with_includes_should_not_drop_any_include
     # heat habtm cache
     car = Car.incl_engines.incl_tyres.first
@@ -165,6 +157,17 @@ class RelationTest < ActiveRecord::TestCase
     end
   end
 
+  def test_select_with_subquery_in_from_does_not_use_original_table_name
+    relation = Comment.group(:type).select('COUNT(post_id) AS post_count, type')
+    subquery = Comment.from(relation).select('type','post_count')
+    assert_equal(relation.map(&:post_count).sort,subquery.map(&:post_count).sort)
+  end
+
+  def test_group_with_subquery_in_from_does_not_use_original_table_name
+    relation = Comment.group(:type).select('COUNT(post_id) AS post_count,type')
+    subquery = Comment.from(relation).group('type').average("post_count")
+    assert_equal(relation.map(&:post_count).sort,subquery.values.sort)
+  end
 
   def test_finding_with_conditions
     assert_equal ["David"], Author.where(:name => 'David').map(&:name)
@@ -350,7 +353,9 @@ class RelationTest < ActiveRecord::TestCase
       assert_equal 0,     Developer.none.size
       assert_equal 0,     Developer.none.count
       assert_equal true,  Developer.none.empty?
+      assert_equal true, Developer.none.none?
       assert_equal false, Developer.none.any?
+      assert_equal false, Developer.none.one?
       assert_equal false, Developer.none.many?
     end
   end
@@ -616,6 +621,51 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal 1, query.to_a.size
   end
 
+  def test_preloading_with_associations_and_merges
+    post = Post.create! title: 'Uhuu', body: 'body'
+    reader = Reader.create! post_id: post.id, person_id: 1
+    comment = Comment.create! post_id: post.id, body: 'body'
+
+    assert !comment.respond_to?(:readers)
+
+    post_rel = Post.preload(:readers).joins(:readers).where(title: 'Uhuu')
+    result_comment = Comment.joins(:post).merge(post_rel).to_a.first
+    assert_equal comment, result_comment
+
+    assert_no_queries do
+      assert_equal post, result_comment.post
+      assert_equal [reader], result_comment.post.readers.to_a
+    end
+
+    post_rel = Post.includes(:readers).where(title: 'Uhuu')
+    result_comment = Comment.joins(:post).merge(post_rel).first
+    assert_equal comment, result_comment
+
+    assert_no_queries do
+      assert_equal post, result_comment.post
+      assert_equal [reader], result_comment.post.readers.to_a
+    end
+  end
+
+  def test_preloading_with_associations_default_scopes_and_merges
+    post = Post.create! title: 'Uhuu', body: 'body'
+    reader = Reader.create! post_id: post.id, person_id: 1
+
+    post_rel = PostWithPreloadDefaultScope.preload(:readers).joins(:readers).where(title: 'Uhuu')
+    result_post = PostWithPreloadDefaultScope.all.merge(post_rel).to_a.first
+
+    assert_no_queries do
+      assert_equal [reader], result_post.readers.to_a
+    end
+
+    post_rel = PostWithIncludesDefaultScope.includes(:readers).where(title: 'Uhuu')
+    result_post = PostWithIncludesDefaultScope.all.merge(post_rel).to_a.first
+
+    assert_no_queries do
+      assert_equal [reader], result_post.readers.to_a
+    end
+  end
+
   def test_loading_with_one_association
     posts = Post.preload(:comments)
     post = posts.find { |p| p.id == 1 }
@@ -857,6 +907,12 @@ class RelationTest < ActiveRecord::TestCase
     assert ! fake.exists?(authors(:david).id)
   end
 
+  def test_exists_uses_existing_scope
+    post = authors(:david).posts.first
+    authors = Author.includes(:posts).where(name: "David", posts: { id: post.id })
+    assert authors.exists?(authors(:david).id)
+  end
+
   def test_last
     authors = Author.all
     assert_equal authors(:bob), authors.last
@@ -875,6 +931,12 @@ class RelationTest < ActiveRecord::TestCase
     assert davids.loaded?
   end
 
+  def test_destroy_all_with_conditions_is_deprecated
+    assert_deprecated do
+      assert_difference('Author.count', -1) { Author.destroy_all(name: 'David') }
+    end
+  end
+
   def test_delete_all
     davids = Author.where(:name => 'David')
 
@@ -882,6 +944,12 @@ class RelationTest < ActiveRecord::TestCase
     assert ! davids.loaded?
   end
 
+  def test_delete_all_with_conditions_is_deprecated
+    assert_deprecated do
+      assert_difference('Author.count', -1) { Author.delete_all(name: 'David') }
+    end
+  end
+
   def test_delete_all_loaded
     davids = Author.where(:name => 'David')
 
@@ -897,7 +965,7 @@ class RelationTest < ActiveRecord::TestCase
 
   def test_delete_all_with_unpermitted_relation_raises_error
     assert_raises(ActiveRecord::ActiveRecordError) { Author.limit(10).delete_all }
-    assert_raises(ActiveRecord::ActiveRecordError) { Author.uniq.delete_all }
+    assert_raises(ActiveRecord::ActiveRecordError) { Author.distinct.delete_all }
     assert_raises(ActiveRecord::ActiveRecordError) { Author.group(:name).delete_all }
     assert_raises(ActiveRecord::ActiveRecordError) { Author.having('SUM(id) < 3').delete_all }
     assert_raises(ActiveRecord::ActiveRecordError) { Author.offset(10).delete_all }
@@ -1104,6 +1172,38 @@ class RelationTest < ActiveRecord::TestCase
     assert ! posts.limit(1).many?
   end
 
+  def test_none?
+    posts = Post.all
+    assert_queries(1) do
+      assert ! posts.none? # Uses COUNT()
+    end
+
+    assert ! posts.loaded?
+
+    assert_queries(1) do
+      assert posts.none? {|p| p.id < 0 }
+      assert ! posts.none? {|p| p.id == 1 }
+    end
+
+    assert posts.loaded?
+  end
+
+  def test_one
+    posts = Post.all
+    assert_queries(1) do
+      assert ! posts.one? # Uses COUNT()
+    end
+
+    assert ! posts.loaded?
+
+    assert_queries(1) do
+      assert ! posts.one? {|p| p.id < 3 }
+      assert posts.one? {|p| p.id == 1 }
+    end
+
+    assert posts.loaded?
+  end
+
   def test_build
     posts = Post.all
 
@@ -1441,6 +1541,13 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal 'David', topic2.reload.author_name
   end
 
+  def test_update_on_relation_passing_active_record_object_is_deprecated
+    topic = Topic.create!(title: 'Foo', author_name: nil)
+    assert_deprecated(/update/) do
+      Topic.where(id: topic.id).update(topic, title: 'Bar')
+    end
+  end
+
   def test_distinct
     tag1 = Tag.create(:name => 'Foo')
     tag2 = Tag.create(:name => 'Foo')
@@ -1450,22 +1557,46 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal ['Foo', 'Foo'], query.map(&:name)
     assert_sql(/DISTINCT/) do
       assert_equal ['Foo'], query.distinct.map(&:name)
-      assert_equal ['Foo'], query.uniq.map(&:name)
+      assert_deprecated { assert_equal ['Foo'], query.uniq.map(&:name) }
     end
     assert_sql(/DISTINCT/) do
       assert_equal ['Foo'], query.distinct(true).map(&:name)
-      assert_equal ['Foo'], query.uniq(true).map(&:name)
+      assert_deprecated { assert_equal ['Foo'], query.uniq(true).map(&:name) }
     end
     assert_equal ['Foo', 'Foo'], query.distinct(true).distinct(false).map(&:name)
-    assert_equal ['Foo', 'Foo'], query.uniq(true).uniq(false).map(&:name)
+
+    assert_deprecated do
+      assert_equal ['Foo', 'Foo'], query.uniq(true).uniq(false).map(&:name)
+    end
   end
 
   def test_doesnt_add_having_values_if_options_are_blank
     scope = Post.having('')
-    assert_equal [], scope.having_values
+    assert scope.having_clause.empty?
 
     scope = Post.having([])
-    assert_equal [], scope.having_values
+    assert scope.having_clause.empty?
+  end
+
+  def test_having_with_binds_for_both_where_and_having
+    post = Post.first
+    having_then_where = Post.having(id: post.id).where(title: post.title).group(:id)
+    where_then_having = Post.where(title: post.title).having(id: post.id).group(:id)
+
+    assert_equal [post], having_then_where
+    assert_equal [post], where_then_having
+  end
+
+  def test_multiple_where_and_having_clauses
+    post = Post.first
+    having_then_where = Post.having(id: post.id).where(title: post.title)
+      .having(id: post.id).where(title: post.title).group(:id)
+
+    assert_equal [post], having_then_where
+  end
+
+  def test_grouping_by_column_with_reserved_name
+    assert_equal [], Possession.select(:where).group(:where).to_a
   end
 
   def test_references_triggers_eager_loading
@@ -1593,6 +1724,10 @@ class RelationTest < ActiveRecord::TestCase
     assert_sql(/^((?!ORDER).)*$/) { Post.all.find_by(author_id: 2) }
   end
 
+  test "find_by requires at least one argument" do
+    assert_raises(ArgumentError) { Post.all.find_by }
+  end
+
   test "find_by! with hash conditions returns the first matching record" do
     assert_equal posts(:eager_other), Post.order(:id).find_by!(author_id: 2)
   end
@@ -1615,6 +1750,10 @@ class RelationTest < ActiveRecord::TestCase
     end
   end
 
+  test "find_by! requires at least one argument" do
+    assert_raises(ArgumentError) { Post.all.find_by! }
+  end
+
   test "loaded relations cannot be mutated by multi value methods" do
     relation = Post.all
     relation.to_a
@@ -1744,14 +1883,13 @@ class RelationTest < ActiveRecord::TestCase
   end
 
   def test_merging_keeps_lhs_bind_parameters
-    column = Post.columns_hash['id']
-    binds = [[column, 20]]
+    binds = [ActiveRecord::Relation::QueryAttribute.new("id", 20, Post.type_for_attribute("id"))]
 
     right  = Post.where(id: 20)
     left   = Post.where(id: 10)
 
     merged = left.merge(right)
-    assert_equal binds, merged.bind_values
+    assert_equal binds, merged.bound_attributes
   end
 
   def test_merging_reorders_bind_params
diff --git a/activerecord/test/cases/reload_models_test.rb b/activerecord/test/cases/reload_models_test.rb
index 0d16a3526f..431fbf1297 100644
--- a/activerecord/test/cases/reload_models_test.rb
+++ b/activerecord/test/cases/reload_models_test.rb
@@ -3,7 +3,7 @@ require 'models/owner'
 require 'models/pet'
 
 class ReloadModelsTest < ActiveRecord::TestCase
-  fixtures :pets
+  fixtures :pets, :owners
 
   def test_has_one_with_reload
     pet = Pet.find_by_name('parrot')
diff --git a/activerecord/test/cases/sanitize_test.rb b/activerecord/test/cases/sanitize_test.rb
index 262e0abc22..14e392ac30 100644
--- a/activerecord/test/cases/sanitize_test.rb
+++ b/activerecord/test/cases/sanitize_test.rb
@@ -9,11 +9,11 @@ class SanitizeTest < ActiveRecord::TestCase
 
   def test_sanitize_sql_array_handles_string_interpolation
     quoted_bambi = ActiveRecord::Base.connection.quote_string("Bambi")
-    assert_equal "name=#{quoted_bambi}", Binary.send(:sanitize_sql_array, ["name=%s", "Bambi"])
-    assert_equal "name=#{quoted_bambi}", Binary.send(:sanitize_sql_array, ["name=%s", "Bambi".mb_chars])
+    assert_equal "name='#{quoted_bambi}'", Binary.send(:sanitize_sql_array, ["name='%s'", "Bambi"])
+    assert_equal "name='#{quoted_bambi}'", Binary.send(:sanitize_sql_array, ["name='%s'", "Bambi".mb_chars])
     quoted_bambi_and_thumper = ActiveRecord::Base.connection.quote_string("Bambi\nand\nThumper")
-    assert_equal "name=#{quoted_bambi_and_thumper}",Binary.send(:sanitize_sql_array, ["name=%s", "Bambi\nand\nThumper"])
-    assert_equal "name=#{quoted_bambi_and_thumper}",Binary.send(:sanitize_sql_array, ["name=%s", "Bambi\nand\nThumper".mb_chars])
+    assert_equal "name='#{quoted_bambi_and_thumper}'",Binary.send(:sanitize_sql_array, ["name='%s'", "Bambi\nand\nThumper"])
+    assert_equal "name='#{quoted_bambi_and_thumper}'",Binary.send(:sanitize_sql_array, ["name='%s'", "Bambi\nand\nThumper".mb_chars])
   end
 
   def test_sanitize_sql_array_handles_bind_variables
diff --git a/activerecord/test/cases/schema_dumper_test.rb b/activerecord/test/cases/schema_dumper_test.rb
index b52c66356c..2a2c2bc8d0 100644
--- a/activerecord/test/cases/schema_dumper_test.rb
+++ b/activerecord/test/cases/schema_dumper_test.rb
@@ -3,7 +3,7 @@ require 'support/schema_dumping_helper'
 
 class SchemaDumperTest < ActiveRecord::TestCase
   include SchemaDumpingHelper
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   setup do
     ActiveRecord::SchemaMigration.create_table
@@ -73,10 +73,10 @@ class SchemaDumperTest < ActiveRecord::TestCase
       next if column_set.empty?
 
       lengths = column_set.map do |column|
-        if match = column.match(/t\.(?:integer|decimal|float|datetime|timestamp|time|date|text|binary|string|boolean|uuid|point)\s+"/)
+        if match = column.match(/\bt\.\w+\s+"/)
           match[0].length
         end
-      end
+      end.compact
 
       assert_equal 1, lengths.uniq.length
     end
@@ -168,24 +168,24 @@ class SchemaDumperTest < ActiveRecord::TestCase
   end
 
   def test_schema_dumps_index_columns_in_right_order
-    index_definition = standard_dump.split(/\n/).grep(/add_index.*companies/).first.strip
+    index_definition = standard_dump.split(/\n/).grep(/t\.index.*company_index/).first.strip
     if current_adapter?(:MysqlAdapter, :Mysql2Adapter, :PostgreSQLAdapter)
-      assert_equal 'add_index "companies", ["firm_id", "type", "rating"], name: "company_index", using: :btree', index_definition
+      assert_equal 't.index ["firm_id", "type", "rating"], name: "company_index", using: :btree', index_definition
     else
-      assert_equal 'add_index "companies", ["firm_id", "type", "rating"], name: "company_index"', index_definition
+      assert_equal 't.index ["firm_id", "type", "rating"], name: "company_index"', index_definition
     end
   end
 
   def test_schema_dumps_partial_indices
-    index_definition = standard_dump.split(/\n/).grep(/add_index.*company_partial_index/).first.strip
+    index_definition = standard_dump.split(/\n/).grep(/t\.index.*company_partial_index/).first.strip
     if current_adapter?(:PostgreSQLAdapter)
-      assert_equal 'add_index "companies", ["firm_id", "type"], name: "company_partial_index", where: "(rating > 10)", using: :btree', index_definition
+      assert_equal 't.index ["firm_id", "type"], name: "company_partial_index", where: "(rating > 10)", using: :btree', index_definition
     elsif current_adapter?(:MysqlAdapter, :Mysql2Adapter)
-      assert_equal 'add_index "companies", ["firm_id", "type"], name: "company_partial_index", using: :btree', index_definition
+      assert_equal 't.index ["firm_id", "type"], name: "company_partial_index", using: :btree', index_definition
     elsif current_adapter?(:SQLite3Adapter) && ActiveRecord::Base.connection.supports_partial_index?
-      assert_equal 'add_index "companies", ["firm_id", "type"], name: "company_partial_index", where: "rating > 10"', index_definition
+      assert_equal 't.index ["firm_id", "type"], name: "company_partial_index", where: "rating > 10"', index_definition
     else
-      assert_equal 'add_index "companies", ["firm_id", "type"], name: "company_partial_index"', index_definition
+      assert_equal 't.index ["firm_id", "type"], name: "company_partial_index"', index_definition
     end
   end
 
@@ -204,50 +204,58 @@ class SchemaDumperTest < ActiveRecord::TestCase
   if current_adapter?(:MysqlAdapter, :Mysql2Adapter)
     def test_schema_dump_should_add_default_value_for_mysql_text_field
       output = standard_dump
-      assert_match %r{t.text\s+"body",\s+limit: 65535,\s+null: false$}, output
+      assert_match %r{t\.text\s+"body",\s+limit: 65535,\s+null: false$}, output
     end
 
     def test_schema_dump_includes_length_for_mysql_binary_fields
       output = standard_dump
-      assert_match %r{t.binary\s+"var_binary",\s+limit: 255$}, output
-      assert_match %r{t.binary\s+"var_binary_large",\s+limit: 4095$}, output
+      assert_match %r{t\.binary\s+"var_binary",\s+limit: 255$}, output
+      assert_match %r{t\.binary\s+"var_binary_large",\s+limit: 4095$}, output
     end
 
     def test_schema_dump_includes_length_for_mysql_blob_and_text_fields
       output = standard_dump
-      assert_match %r{t.binary\s+"tiny_blob",\s+limit: 255$}, output
-      assert_match %r{t.binary\s+"normal_blob",\s+limit: 65535$}, output
-      assert_match %r{t.binary\s+"medium_blob",\s+limit: 16777215$}, output
-      assert_match %r{t.binary\s+"long_blob",\s+limit: 4294967295$}, output
-      assert_match %r{t.text\s+"tiny_text",\s+limit: 255$}, output
-      assert_match %r{t.text\s+"normal_text",\s+limit: 65535$}, output
-      assert_match %r{t.text\s+"medium_text",\s+limit: 16777215$}, output
-      assert_match %r{t.text\s+"long_text",\s+limit: 4294967295$}, output
+      assert_match %r{t\.blob\s+"tiny_blob",\s+limit: 255$}, output
+      assert_match %r{t\.binary\s+"normal_blob",\s+limit: 65535$}, output
+      assert_match %r{t\.binary\s+"medium_blob",\s+limit: 16777215$}, output
+      assert_match %r{t\.binary\s+"long_blob",\s+limit: 4294967295$}, output
+      assert_match %r{t\.text\s+"tiny_text",\s+limit: 255$}, output
+      assert_match %r{t\.text\s+"normal_text",\s+limit: 65535$}, output
+      assert_match %r{t\.text\s+"medium_text",\s+limit: 16777215$}, output
+      assert_match %r{t\.text\s+"long_text",\s+limit: 4294967295$}, output
     end
 
-    def test_schema_dumps_index_type
+    def test_schema_does_not_include_limit_for_emulated_mysql_boolean_fields
       output = standard_dump
-      assert_match %r{add_index "key_tests", \["awesome"\], name: "index_key_tests_on_awesome", type: :fulltext}, output
-      assert_match %r{add_index "key_tests", \["pizza"\], name: "index_key_tests_on_pizza", using: :btree}, output
+      assert_no_match %r{t\.boolean\s+"has_fun",.+limit: 1}, output
     end
-  end
 
-  if mysql_56?
-    def test_schema_dump_includes_datetime_precision
+    def test_schema_dumps_index_type
       output = standard_dump
-      assert_match %r{t.datetime\s+"written_on",\s+precision: 6$}, output
+      assert_match %r{t\.index \["awesome"\], name: "index_key_tests_on_awesome", type: :fulltext}, output
+      assert_match %r{t\.index \["pizza"\], name: "index_key_tests_on_pizza", using: :btree}, output
     end
   end
 
   def test_schema_dump_includes_decimal_options
     output = dump_all_table_schema([/^[^n]/])
-    assert_match %r{precision: 3,[[:space:]]+scale: 2,[[:space:]]+default: 2.78}, output
+    assert_match %r{precision: 3,[[:space:]]+scale: 2,[[:space:]]+default: "2\.78"}, output
   end
 
   if current_adapter?(:PostgreSQLAdapter)
     def test_schema_dump_includes_bigint_default
       output = standard_dump
-      assert_match %r{t.integer\s+"bigint_default",\s+limit: 8,\s+default: 0}, output
+      assert_match %r{t\.integer\s+"bigint_default",\s+limit: 8,\s+default: 0}, output
+    end
+
+    def test_schema_dump_includes_limit_on_array_type
+      output = standard_dump
+      assert_match %r{t\.integer\s+"big_int_data_points\",\s+limit: 8,\s+array: true}, output
+    end
+
+    def test_schema_dump_allows_array_of_decimal_defaults
+      output = standard_dump
+      assert_match %r{t\.decimal\s+"decimal_array_default",\s+default: \["1.23", "3.45"\],\s+array: true}, output
     end
 
     if ActiveRecord::Base.connection.supports_extensions?
@@ -271,11 +279,11 @@ class SchemaDumperTest < ActiveRecord::TestCase
     output = standard_dump
     # Oracle supports precision up to 38 and it identifies decimals with scale 0 as integers
     if current_adapter?(:OracleAdapter)
-      assert_match %r{t.integer\s+"atoms_in_universe",\s+precision: 38}, output
+      assert_match %r{t\.integer\s+"atoms_in_universe",\s+precision: 38}, output
     elsif current_adapter?(:FbAdapter)
-      assert_match %r{t.integer\s+"atoms_in_universe",\s+precision: 18}, output
+      assert_match %r{t\.integer\s+"atoms_in_universe",\s+precision: 18}, output
     else
-      assert_match %r{t.decimal\s+"atoms_in_universe",\s+precision: 55}, output
+      assert_match %r{t\.decimal\s+"atoms_in_universe",\s+precision: 55}, output
     end
   end
 
@@ -284,7 +292,7 @@ class SchemaDumperTest < ActiveRecord::TestCase
     match = output.match(%r{create_table "goofy_string_id"(.*)do.*\n(.*)\n})
     assert_not_nil(match, "goofy_string_id table not found")
     assert_match %r(id: false), match[1], "no table id not preserved"
-    assert_match %r{t.string\s+"id",.*?null: false$}, match[2], "non-primary key id column not preserved"
+    assert_match %r{t\.string\s+"id",.*?null: false$}, match[2], "non-primary key id column not preserved"
   end
 
   def test_schema_dump_keeps_id_false_when_id_is_false_and_unique_not_null_column_added
@@ -362,7 +370,7 @@ class SchemaDumperDefaultsTest < ActiveRecord::TestCase
 
   teardown do
     return unless @connection
-    @connection.execute 'DROP TABLE defaults' if @connection.table_exists? 'defaults'
+    @connection.drop_table 'defaults', if_exists: true
   end
 
   def test_schema_dump_defaults_with_universally_supported_types
diff --git a/activerecord/test/cases/scoping/default_scoping_test.rb b/activerecord/test/cases/scoping/default_scoping_test.rb
index 0738df1b54..86316ab476 100644
--- a/activerecord/test/cases/scoping/default_scoping_test.rb
+++ b/activerecord/test/cases/scoping/default_scoping_test.rb
@@ -3,6 +3,7 @@ require 'models/post'
 require 'models/comment'
 require 'models/developer'
 require 'models/computer'
+require 'models/vehicle'
 
 class DefaultScopingTest < ActiveRecord::TestCase
   fixtures :developers, :posts, :comments
@@ -153,6 +154,18 @@ class DefaultScopingTest < ActiveRecord::TestCase
     assert_equal expected_7, received_7
   end
 
+  def test_unscope_comparison_where_clauses
+    # unscoped for WHERE (`developers`.`id` <= 2)
+    expected = Developer.order('salary DESC').collect(&:name)
+    received = DeveloperOrderedBySalary.where(id: -Float::INFINITY..2).unscope(where: :id).collect { |dev| dev.name }
+    assert_equal expected, received
+
+    # unscoped for WHERE (`developers`.`id` < 2)
+    expected = Developer.order('salary DESC').collect(&:name)
+    received = DeveloperOrderedBySalary.where(id: -Float::INFINITY...2).unscope(where: :id).collect { |dev| dev.name }
+    assert_equal expected, received
+  end
+
   def test_unscope_multiple_where_clauses
     expected = Developer.order('salary DESC').collect(&:name)
     received = DeveloperOrderedBySalary.where(name: 'Jamis').where(id: 1).unscope(where: [:name, :id]).collect(&:name)
@@ -284,8 +297,8 @@ class DefaultScopingTest < ActiveRecord::TestCase
 
   def test_unscope_merging
     merged = Developer.where(name: "Jamis").merge(Developer.unscope(:where))
-    assert merged.where_values.empty?
-    assert !merged.where(name: "Jon").where_values.empty?
+    assert merged.where_clause.empty?
+    assert !merged.where(name: "Jon").where_clause.empty?
   end
 
   def test_order_in_default_scope_should_not_prevail
@@ -426,19 +439,24 @@ class DefaultScopingTest < ActiveRecord::TestCase
 
   test "additional conditions are ANDed with the default scope" do
     scope = DeveloperCalledJamis.where(name: "David")
-    assert_equal 2, scope.where_values.length
+    assert_equal 2, scope.where_clause.ast.children.length
     assert_equal [], scope.to_a
   end
 
   test "additional conditions in a scope are ANDed with the default scope" do
     scope = DeveloperCalledJamis.david
-    assert_equal 2, scope.where_values.length
+    assert_equal 2, scope.where_clause.ast.children.length
     assert_equal [], scope.to_a
   end
 
   test "a scope can remove the condition from the default scope" do
     scope = DeveloperCalledJamis.david2
-    assert_equal 1, scope.where_values.length
-    assert_equal Developer.where(name: "David").map(&:id), scope.map(&:id)
+    assert_equal 1, scope.where_clause.ast.children.length
+    assert_equal Developer.where(name: "David"), scope
+  end
+
+  def test_with_abstract_class_where_clause_should_not_be_duplicated
+    scope = Bus.all
+    assert_equal scope.where_clause.ast.children.length, 1
   end
 end
diff --git a/activerecord/test/cases/scoping/named_scoping_test.rb b/activerecord/test/cases/scoping/named_scoping_test.rb
index 41f3449828..7a8eaeccb7 100644
--- a/activerecord/test/cases/scoping/named_scoping_test.rb
+++ b/activerecord/test/cases/scoping/named_scoping_test.rb
@@ -188,8 +188,9 @@ class NamedScopingTest < ActiveRecord::TestCase
   def test_any_should_call_proxy_found_if_using_a_block
     topics = Topic.base
     assert_queries(1) do
-      topics.expects(:empty?).never
-      topics.any? { true }
+      assert_not_called(topics, :empty?) do
+        topics.any? { true }
+      end
     end
   end
 
@@ -217,8 +218,9 @@ class NamedScopingTest < ActiveRecord::TestCase
   def test_many_should_call_proxy_found_if_using_a_block
     topics = Topic.base
     assert_queries(1) do
-      topics.expects(:size).never
-      topics.many? { true }
+      assert_not_called(topics, :size) do
+        topics.many? { true }
+      end
     end
   end
 
@@ -317,13 +319,15 @@ class NamedScopingTest < ActiveRecord::TestCase
     ]
 
     conflicts.each do |name|
-      assert_raises(ArgumentError, "scope `#{name}` should not be allowed") do
+      e = assert_raises(ArgumentError, "scope `#{name}` should not be allowed") do
         klass.class_eval { scope name, ->{ where(approved: true) } }
       end
+      assert_match(/You tried to define a scope named \"#{name}\" on the model/, e.message)
 
-      assert_raises(ArgumentError, "scope `#{name}` should not be allowed") do
+      e = assert_raises(ArgumentError, "scope `#{name}` should not be allowed") do
         subklass.class_eval { scope name, ->{ where(approved: true) } }
       end
+      assert_match(/You tried to define a scope named \"#{name}\" on the model/, e.message)
     end
 
     non_conflicts.each do |name|
@@ -380,8 +384,8 @@ class NamedScopingTest < ActiveRecord::TestCase
   end
 
   def test_should_not_duplicates_where_values
-    where_values = Topic.where("1=1").scope_with_lambda.where_values
-    assert_equal ["1=1"], where_values
+    relation = Topic.where("1=1")
+    assert_equal relation.where_clause, relation.scope_with_lambda.where_clause
   end
 
   def test_chaining_with_duplicate_joins
diff --git a/activerecord/test/cases/scoping/relation_scoping_test.rb b/activerecord/test/cases/scoping/relation_scoping_test.rb
index d7bcbf6203..4bfffbe9c6 100644
--- a/activerecord/test/cases/scoping/relation_scoping_test.rb
+++ b/activerecord/test/cases/scoping/relation_scoping_test.rb
@@ -184,7 +184,7 @@ class RelationScopingTest < ActiveRecord::TestCase
     rescue
     end
 
-    assert !Developer.all.where_values.include?("name = 'Jamis'")
+    assert_not Developer.all.to_sql.include?("name = 'Jamis'"), "scope was not restored"
   end
 
   def test_default_scope_filters_on_joins
@@ -208,6 +208,12 @@ class RelationScopingTest < ActiveRecord::TestCase
     assert_equal [], DeveloperFilteredOnJoins.all
     assert_not_equal [], Developer.all
   end
+
+  def test_current_scope_does_not_pollute_other_subclasses
+    Post.none.scoping do
+      assert StiPost.all.any?
+    end
+  end
 end
 
 class NestedRelationScopingTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/secure_token_test.rb b/activerecord/test/cases/secure_token_test.rb
index 3f7455d12d..e731443fc2 100644
--- a/activerecord/test/cases/secure_token_test.rb
+++ b/activerecord/test/cases/secure_token_test.rb
@@ -22,4 +22,11 @@ class SecureTokenTest < ActiveRecord::TestCase
     assert_not_equal @user.token, old_token
     assert_not_equal @user.auth_token, old_auth_token
   end
+
+  def test_token_value_not_overwritten_when_present
+    @user.token = "custom-secure-token"
+    @user.save
+
+    assert_equal @user.token, "custom-secure-token"
+  end
 end
diff --git a/activerecord/test/cases/serialization_test.rb b/activerecord/test/cases/serialization_test.rb
index 35b13ea247..14b80f4df4 100644
--- a/activerecord/test/cases/serialization_test.rb
+++ b/activerecord/test/cases/serialization_test.rb
@@ -8,7 +8,7 @@ require 'models/post'
 class SerializationTest < ActiveRecord::TestCase
   fixtures :books
 
-  FORMATS = [ :xml, :json ]
+  FORMATS = [ :json ]
 
   def setup
     @contact_attributes = {
diff --git a/activerecord/test/cases/serialized_attribute_test.rb b/activerecord/test/cases/serialized_attribute_test.rb
index e29f7462c8..6056156698 100644
--- a/activerecord/test/cases/serialized_attribute_test.rb
+++ b/activerecord/test/cases/serialized_attribute_test.rb
@@ -264,4 +264,35 @@ class SerializedAttributeTest < ActiveRecord::TestCase
       Topic.serialize(:content, Regexp)
     end
   end
+
+  def test_newly_emptied_serialized_hash_is_changed
+    Topic.serialize(:content, Hash)
+    topic = Topic.create(content: { "things" => "stuff" })
+    topic.content.delete("things")
+    topic.save!
+    topic.reload
+
+    assert_equal({}, topic.content)
+  end
+
+  def test_values_cast_from_nil_are_persisted_as_nil
+    # This is required to fulfil the following contract, which must be universally
+    # true in Active Record:
+    #
+    # model.attribute = value
+    # assert_equal model.attribute, model.tap(&:save).reload.attribute
+    Topic.serialize(:content, Hash)
+    topic = Topic.create!(content: {})
+    topic2 = Topic.create!(content: nil)
+
+    assert_equal [topic, topic2], Topic.where(content: nil)
+  end
+
+  def test_nil_is_always_persisted_as_null
+    Topic.serialize(:content, Hash)
+
+    topic = Topic.create!(content: { foo: "bar" })
+    topic.update_attribute :content, nil
+    assert_equal [topic], Topic.where(content: nil)
+  end
 end
diff --git a/activerecord/test/cases/suppressor_test.rb b/activerecord/test/cases/suppressor_test.rb
new file mode 100644
index 0000000000..72c5c16555
--- /dev/null
+++ b/activerecord/test/cases/suppressor_test.rb
@@ -0,0 +1,52 @@
+require 'cases/helper'
+require 'models/notification'
+require 'models/user'
+
+class SuppressorTest < ActiveRecord::TestCase
+  def test_suppresses_create
+    assert_no_difference -> { Notification.count } do
+      Notification.suppress do
+        Notification.create
+        Notification.create!
+        Notification.new.save
+        Notification.new.save!
+      end
+    end
+  end
+
+  def test_suppresses_update
+    user = User.create! token: 'asdf'
+
+    User.suppress do
+      user.update token: 'ghjkl'
+      assert_equal 'asdf', user.reload.token
+
+      user.update! token: 'zxcvbnm'
+      assert_equal 'asdf', user.reload.token
+
+      user.token = 'qwerty'
+      user.save
+      assert_equal 'asdf', user.reload.token
+
+      user.token = 'uiop'
+      user.save!
+      assert_equal 'asdf', user.reload.token
+    end
+  end
+
+  def test_suppresses_create_in_callback
+    assert_difference -> { User.count } do
+      assert_no_difference -> { Notification.count } do
+        Notification.suppress { UserWithNotification.create! }
+      end
+    end
+  end
+
+  def test_resumes_saving_after_suppression_complete
+    Notification.suppress { UserWithNotification.create! }
+
+    assert_difference -> { Notification.count } do
+      Notification.create!
+    end
+  end
+end
diff --git a/activerecord/test/cases/tasks/database_tasks_test.rb b/activerecord/test/cases/tasks/database_tasks_test.rb
index 2fa033ed45..c8f4179313 100644
--- a/activerecord/test/cases/tasks/database_tasks_test.rb
+++ b/activerecord/test/cases/tasks/database_tasks_test.rb
@@ -277,12 +277,14 @@ module ActiveRecord
     def test_migrate_receives_correct_env_vars
       verbose, version = ENV['VERBOSE'], ENV['VERSION']
 
+      ActiveRecord::Tasks::DatabaseTasks.migrations_paths = 'custom/path'
       ENV['VERBOSE'] = 'false'
       ENV['VERSION'] = '4'
 
-      ActiveRecord::Migrator.expects(:migrate).with(ActiveRecord::Migrator.migrations_paths, 4)
+      ActiveRecord::Migrator.expects(:migrate).with('custom/path', 4)
       ActiveRecord::Tasks::DatabaseTasks.migrate
     ensure
+      ActiveRecord::Tasks::DatabaseTasks.migrations_paths = nil
       ENV['VERBOSE'], ENV['VERSION'] = verbose, version
     end
   end
@@ -377,4 +379,20 @@ module ActiveRecord
       ActiveRecord::Tasks::DatabaseTasks.check_schema_file("awesome-file.sql")
     end
   end
+
+  class DatabaseTasksCheckSchemaFileDefaultsTest < ActiveRecord::TestCase
+    def test_check_schema_file_defaults
+      ActiveRecord::Tasks::DatabaseTasks.stubs(:db_dir).returns('/tmp')
+      assert_equal '/tmp/schema.rb', ActiveRecord::Tasks::DatabaseTasks.schema_file
+    end
+  end
+
+  class DatabaseTasksCheckSchemaFileSpecifiedFormatsTest < ActiveRecord::TestCase
+    {ruby: 'schema.rb', sql: 'structure.sql'}.each_pair do |fmt, filename|
+      define_method("test_check_schema_file_for_#{fmt}_format") do
+        ActiveRecord::Tasks::DatabaseTasks.stubs(:db_dir).returns('/tmp')
+        assert_equal "/tmp/#{filename}", ActiveRecord::Tasks::DatabaseTasks.schema_file(fmt)
+      end
+    end
+  end
 end
diff --git a/activerecord/test/cases/tasks/mysql_rake_test.rb b/activerecord/test/cases/tasks/mysql_rake_test.rb
index f58535f044..a93fa57257 100644
--- a/activerecord/test/cases/tasks/mysql_rake_test.rb
+++ b/activerecord/test/cases/tasks/mysql_rake_test.rb
@@ -265,30 +265,40 @@ module ActiveRecord
 
     def test_structure_dump
       filename = "awesome-file.sql"
-      Kernel.expects(:system).with("mysqldump", "--result-file", filename, "--no-data", "test-db").returns(true)
+      Kernel.expects(:system).with("mysqldump", "--result-file", filename, "--no-data", "--routines", "test-db").returns(true)
 
       ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, filename)
     end
 
-    def test_warn_when_external_structure_dump_fails
+    def test_warn_when_external_structure_dump_command_execution_fails
       filename = "awesome-file.sql"
-      Kernel.expects(:system).with("mysqldump", "--result-file", filename, "--no-data", "test-db").returns(false)
+      Kernel.expects(:system)
+        .with("mysqldump", "--result-file", filename, "--no-data", "--routines", "test-db")
+        .returns(false)
 
-      warnings = capture(:stderr) do
+      e = assert_raise(RuntimeError) {
         ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, filename)
-      end
-
-      assert_match(/Could not dump the database structure/, warnings)
+      }
+      assert_match(/^failed to execute: `mysqldump`$/, e.message)
     end
 
     def test_structure_dump_with_port_number
       filename = "awesome-file.sql"
-      Kernel.expects(:system).with("mysqldump", "--port", "10000", "--result-file", filename, "--no-data", "test-db").returns(true)
+      Kernel.expects(:system).with("mysqldump", "--port=10000", "--result-file", filename, "--no-data", "--routines", "test-db").returns(true)
 
       ActiveRecord::Tasks::DatabaseTasks.structure_dump(
         @configuration.merge('port' => 10000),
         filename)
     end
+
+    def test_structure_dump_with_ssl
+      filename = "awesome-file.sql"
+      Kernel.expects(:system).with("mysqldump", "--ssl-ca=ca.crt", "--result-file", filename, "--no-data", "--routines", "test-db").returns(true)
+
+      ActiveRecord::Tasks::DatabaseTasks.structure_dump(
+        @configuration.merge("sslca" => "ca.crt"),
+        filename)
+    end
   end
 
   class MySQLStructureLoadTest < ActiveRecord::TestCase
@@ -302,6 +312,7 @@ module ActiveRecord
     def test_structure_load
       filename = "awesome-file.sql"
       Kernel.expects(:system).with('mysql', '--execute', %{SET FOREIGN_KEY_CHECKS = 0; SOURCE #{filename}; SET FOREIGN_KEY_CHECKS = 1}, "--database", "test-db")
+        .returns(true)
 
       ActiveRecord::Tasks::DatabaseTasks.structure_load(@configuration, filename)
     end
diff --git a/activerecord/test/cases/tasks/postgresql_rake_test.rb b/activerecord/test/cases/tasks/postgresql_rake_test.rb
index 0d574d071c..c31f94b2f2 100644
--- a/activerecord/test/cases/tasks/postgresql_rake_test.rb
+++ b/activerecord/test/cases/tasks/postgresql_rake_test.rb
@@ -60,7 +60,7 @@ module ActiveRecord
       $stderr.expects(:puts).
         with("Couldn't create database for #{@configuration.inspect}")
 
-      ActiveRecord::Tasks::DatabaseTasks.create @configuration
+      assert_raises(Exception) { ActiveRecord::Tasks::DatabaseTasks.create @configuration }
     end
 
     def test_create_when_database_exists_outputs_info_to_stderr
@@ -195,21 +195,54 @@ module ActiveRecord
         'adapter'  => 'postgresql',
         'database' => 'my-app-db'
       }
+      @filename = "awesome-file.sql"
 
       ActiveRecord::Base.stubs(:connection).returns(@connection)
       ActiveRecord::Base.stubs(:establish_connection).returns(true)
       Kernel.stubs(:system)
+      File.stubs(:open)
     end
 
     def test_structure_dump
-      filename = "awesome-file.sql"
-      Kernel.expects(:system).with("pg_dump -i -s -x -O -f #{filename}  my-app-db").returns(true)
-      @connection.expects(:schema_search_path).returns("foo")
+      Kernel.expects(:system).with('pg_dump', '-s', '-x', '-O', '-f', @filename, 'my-app-db').returns(true)
+
+      ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
+    end
+
+    def test_structure_dump_with_schema_search_path
+      @configuration['schema_search_path'] = 'foo,bar'
+
+      Kernel.expects(:system).with('pg_dump', '-s', '-x', '-O', '-f', @filename, '--schema=foo --schema=bar', 'my-app-db').returns(true)
+
+      ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
+    end
+
+    def test_structure_dump_with_schema_search_path_and_dump_schemas_all
+      @configuration['schema_search_path'] = 'foo,bar'
+
+      Kernel.expects(:system).with("pg_dump", '-s', '-x', '-O', '-f', @filename,  'my-app-db').returns(true)
+
+      with_dump_schemas(:all) do
+        ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
+      end
+    end
+
+    def test_structure_dump_with_dump_schemas_string
+      Kernel.expects(:system).with("pg_dump", '-s', '-x', '-O', '-f', @filename, '--schema=foo --schema=bar', "my-app-db").returns(true)
+
+      with_dump_schemas('foo,bar') do
+        ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
+      end
+    end
+
+    private
 
-      ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, filename)
-      assert File.exist?(filename)
+    def with_dump_schemas(value, &block)
+      old_dump_schemas = ActiveRecord::Base.dump_schemas
+      ActiveRecord::Base.dump_schemas = value
+      yield
     ensure
-      FileUtils.rm(filename)
+      ActiveRecord::Base.dump_schemas = old_dump_schemas
     end
   end
 
@@ -228,14 +261,14 @@ module ActiveRecord
 
     def test_structure_load
       filename = "awesome-file.sql"
-      Kernel.expects(:system).with("psql -q -f #{filename} my-app-db")
+      Kernel.expects(:system).with('psql', '-q', '-f', filename, @configuration['database']).returns(true)
 
       ActiveRecord::Tasks::DatabaseTasks.structure_load(@configuration, filename)
     end
 
     def test_structure_load_accepts_path_with_spaces
       filename = "awesome file.sql"
-      Kernel.expects(:system).with("psql -q -f awesome\\ file.sql my-app-db")
+      Kernel.expects(:system).with('psql', '-q', '-f', filename, @configuration['database']).returns(true)
 
       ActiveRecord::Tasks::DatabaseTasks.structure_load(@configuration, filename)
     end
diff --git a/activerecord/test/cases/tasks/sqlite_rake_test.rb b/activerecord/test/cases/tasks/sqlite_rake_test.rb
index 750d5e42dc..0aea0c3b38 100644
--- a/activerecord/test/cases/tasks/sqlite_rake_test.rb
+++ b/activerecord/test/cases/tasks/sqlite_rake_test.rb
@@ -53,7 +53,7 @@ module ActiveRecord
       $stderr.expects(:puts).
         with("Couldn't create database for #{@configuration.inspect}")
 
-      ActiveRecord::Tasks::DatabaseTasks.create @configuration, '/rails/root'
+      assert_raises(Exception) { ActiveRecord::Tasks::DatabaseTasks.create @configuration, '/rails/root' }
     end
   end
 
diff --git a/activerecord/test/cases/test_case.rb b/activerecord/test/cases/test_case.rb
index 5ba17359f0..47e664f4e7 100644
--- a/activerecord/test/cases/test_case.rb
+++ b/activerecord/test/cases/test_case.rb
@@ -1,10 +1,13 @@
 require 'active_support/test_case'
+require 'active_support/testing/stream'
 
 module ActiveRecord
   # = Active Record Test Case
   #
   # Defines some test assertions to test against SQL queries.
   class TestCase < ActiveSupport::TestCase #:nodoc:
+    include ActiveSupport::Testing::Stream
+
     def teardown
       SQLCounter.clear_log
     end
@@ -13,23 +16,6 @@ module ActiveRecord
       assert_equal expected.to_s, actual.to_s, message
     end
 
-    def capture(stream)
-      stream = stream.to_s
-      captured_stream = Tempfile.new(stream)
-      stream_io = eval("$#{stream}")
-      origin_stream = stream_io.dup
-      stream_io.reopen(captured_stream)
-
-      yield
-
-      stream_io.rewind
-      return captured_stream.read
-    ensure
-      captured_stream.close
-      captured_stream.unlink
-      stream_io.reopen(origin_stream)
-    end
-
     def capture_sql
       SQLCounter.clear_log
       yield
@@ -79,6 +65,30 @@ module ActiveRecord
     end
   end
 
+  class PostgreSQLTestCase < TestCase
+    def self.run(*args)
+      super if current_adapter?(:PostgreSQLAdapter)
+    end
+  end
+
+  class Mysql2TestCase < TestCase
+    def self.run(*args)
+      super if current_adapter?(:Mysql2Adapter)
+    end
+  end
+
+  class MysqlTestCase < TestCase
+    def self.run(*args)
+      super if current_adapter?(:MysqlAdapter)
+    end
+  end
+
+  class SQLite3TestCase < TestCase
+    def self.run(*args)
+      super if current_adapter?(:SQLite3Adapter)
+    end
+  end
+
   class SQLCounter
     class << self
       attr_accessor :ignored_sql, :log, :log_all
@@ -93,9 +103,9 @@ module ActiveRecord
     # ignored SQL, or better yet, use a different notification for the queries
     # instead examining the SQL content.
     oracle_ignored     = [/^select .*nextval/i, /^SAVEPOINT/, /^ROLLBACK TO/, /^\s*select .* from all_triggers/im, /^\s*select .* from all_constraints/im, /^\s*select .* from all_tab_cols/im]
-    mysql_ignored      = [/^SHOW TABLES/i, /^SHOW FULL FIELDS/, /^SHOW CREATE TABLE /i, /^SHOW VARIABLES /]
+    mysql_ignored      = [/^SHOW FULL TABLES/i, /^SHOW FULL FIELDS/, /^SHOW CREATE TABLE /i, /^SHOW VARIABLES /, /^\s*SELECT (?:column_name|table_name)\b.*\bFROM information_schema\.(?:key_column_usage|tables)\b/im]
     postgresql_ignored = [/^\s*select\b.*\bfrom\b.*pg_namespace\b/im, /^\s*select tablename\b.*from pg_tables\b/im, /^\s*select\b.*\battname\b.*\bfrom\b.*\bpg_attribute\b/im, /^SHOW search_path/i]
-    sqlite3_ignored =    [/^\s*SELECT name\b.*\bFROM sqlite_master/im]
+    sqlite3_ignored =    [/^\s*SELECT name\b.*\bFROM sqlite_master/im, /^\s*SELECT sql\b.*\bFROM sqlite_master/im]
 
     [oracle_ignored, mysql_ignored, postgresql_ignored, sqlite3_ignored].each do |db_ignored_sql|
       ignored_sql.concat db_ignored_sql
diff --git a/activerecord/test/cases/test_fixtures_test.rb b/activerecord/test/cases/test_fixtures_test.rb
new file mode 100644
index 0000000000..1970fe82d0
--- /dev/null
+++ b/activerecord/test/cases/test_fixtures_test.rb
@@ -0,0 +1,36 @@
+require 'cases/helper'
+
+class TestFixturesTest < ActiveRecord::TestCase
+  setup do
+    @klass = Class.new
+    @klass.send(:include, ActiveRecord::TestFixtures)
+  end
+
+  def test_deprecated_use_transactional_fixtures=
+    assert_deprecated 'use use_transactional_tests= instead' do
+      @klass.use_transactional_fixtures = true
+    end
+  end
+
+  def test_use_transactional_tests_prefers_use_transactional_fixtures
+    ActiveSupport::Deprecation.silence do
+      @klass.use_transactional_fixtures = false
+    end
+
+    assert_equal false, @klass.use_transactional_tests
+  end
+
+  def test_use_transactional_tests_defaults_to_true
+    ActiveSupport::Deprecation.silence do
+      @klass.use_transactional_fixtures = nil
+    end
+
+    assert_equal true, @klass.use_transactional_tests
+  end
+
+  def test_use_transactional_tests_can_be_overridden
+    @klass.use_transactional_tests = "foobar"
+
+    assert_equal "foobar", @klass.use_transactional_tests
+  end
+end
diff --git a/activerecord/test/cases/time_precision_test.rb b/activerecord/test/cases/time_precision_test.rb
new file mode 100644
index 0000000000..ff7a81fe60
--- /dev/null
+++ b/activerecord/test/cases/time_precision_test.rb
@@ -0,0 +1,108 @@
+require 'cases/helper'
+require 'support/schema_dumping_helper'
+
+if ActiveRecord::Base.connection.supports_datetime_with_precision?
+class TimePrecisionTest < ActiveRecord::TestCase
+  include SchemaDumpingHelper
+  self.use_transactional_tests = false
+
+  class Foo < ActiveRecord::Base; end
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+  end
+
+  teardown do
+    @connection.drop_table :foos, if_exists: true
+  end
+
+  def test_time_data_type_with_precision
+    @connection.create_table(:foos, force: true)
+    @connection.add_column :foos, :start,  :time, precision: 3
+    @connection.add_column :foos, :finish, :time, precision: 6
+    assert_equal 3, activerecord_column_option('foos', 'start',  'precision')
+    assert_equal 6, activerecord_column_option('foos', 'finish', 'precision')
+  end
+
+  def test_passing_precision_to_time_does_not_set_limit
+    @connection.create_table(:foos, force: true) do |t|
+      t.time :start,  precision: 3
+      t.time :finish, precision: 6
+    end
+    assert_nil activerecord_column_option('foos', 'start',  'limit')
+    assert_nil activerecord_column_option('foos', 'finish', 'limit')
+  end
+
+  def test_invalid_time_precision_raises_error
+    assert_raises ActiveRecord::ActiveRecordError do
+      @connection.create_table(:foos, force: true) do |t|
+        t.time :start,  precision: 7
+        t.time :finish, precision: 7
+      end
+    end
+  end
+
+  def test_database_agrees_with_activerecord_about_precision
+    @connection.create_table(:foos, force: true) do |t|
+      t.time :start,  precision: 2
+      t.time :finish, precision: 4
+    end
+    assert_equal 2, database_datetime_precision('foos', 'start')
+    assert_equal 4, database_datetime_precision('foos', 'finish')
+  end
+
+  def test_formatting_time_according_to_precision
+    @connection.create_table(:foos, force: true) do |t|
+      t.time :start,  precision: 0
+      t.time :finish, precision: 4
+    end
+    time = ::Time.utc(2000, 1, 1, 12, 30, 0, 999999)
+    Foo.create!(start: time, finish: time)
+    assert foo = Foo.find_by(start: time)
+    assert_equal 1, Foo.where(finish: time).count
+    assert_equal time.to_s, foo.start.to_s
+    assert_equal time.to_s, foo.finish.to_s
+    assert_equal 000000, foo.start.usec
+    assert_equal 999900, foo.finish.usec
+  end
+
+  def test_schema_dump_includes_time_precision
+    @connection.create_table(:foos, force: true) do |t|
+      t.time :start,  precision: 4
+      t.time :finish, precision: 6
+    end
+    output = dump_table_schema("foos")
+    assert_match %r{t\.time\s+"start",\s+precision: 4$}, output
+    assert_match %r{t\.time\s+"finish",\s+precision: 6$}, output
+  end
+
+  if current_adapter?(:PostgreSQLAdapter)
+    def test_time_precision_with_zero_should_be_dumped
+      @connection.create_table(:foos, force: true) do |t|
+        t.time :start,  precision: 0
+        t.time :finish, precision: 0
+      end
+      output = dump_table_schema("foos")
+      assert_match %r{t\.time\s+"start",\s+precision: 0$}, output
+      assert_match %r{t\.time\s+"finish",\s+precision: 0$}, output
+    end
+  end
+
+  private
+
+  def database_datetime_precision(table_name, column_name)
+    results = @connection.exec_query("SELECT column_name, datetime_precision FROM information_schema.columns WHERE table_name = '#{table_name}'")
+    result = results.find do |result_hash|
+      result_hash["column_name"] == column_name
+    end
+    result && result["datetime_precision"].to_i
+  end
+
+  def activerecord_column_option(tablename, column_name, option)
+    result = @connection.columns(tablename).find do |column|
+      column.name == column_name
+    end
+    result && result.send(option)
+  end
+end
+end
diff --git a/activerecord/test/cases/timestamp_test.rb b/activerecord/test/cases/timestamp_test.rb
index db474c63a4..970f6bcf4a 100644
--- a/activerecord/test/cases/timestamp_test.rb
+++ b/activerecord/test/cases/timestamp_test.rb
@@ -73,9 +73,20 @@ class TimestampTest < ActiveRecord::TestCase
     assert_equal @previously_updated_at, @developer.updated_at
   end
 
+  def test_touching_updates_timestamp_with_given_time
+    previously_updated_at = @developer.updated_at 
+    new_time = Time.utc(2015, 2, 16, 0, 0, 0) 
+    @developer.touch(time: new_time) 
+
+    assert_not_equal previously_updated_at, @developer.updated_at 
+    assert_equal new_time, @developer.updated_at 
+  end
+
   def test_touching_an_attribute_updates_timestamp
     previously_created_at = @developer.created_at
-    @developer.touch(:created_at)
+    travel(1.second) do
+      @developer.touch(:created_at)
+    end
 
     assert !@developer.created_at_changed? , 'created_at should not be changed'
     assert !@developer.changed?, 'record should not be changed'
@@ -91,6 +102,18 @@ class TimestampTest < ActiveRecord::TestCase
     assert_in_delta Time.now, task.ending, 1
   end
 
+  def test_touching_an_attribute_updates_timestamp_with_given_time
+    previously_updated_at = @developer.updated_at 
+    previously_created_at = @developer.created_at
+    new_time = Time.utc(2015, 2, 16, 4, 54, 0) 
+    @developer.touch(:created_at, time: new_time)
+
+    assert_not_equal previously_created_at, @developer.created_at
+    assert_not_equal previously_updated_at, @developer.updated_at
+    assert_equal new_time, @developer.created_at
+    assert_equal new_time, @developer.updated_at
+  end
+
   def test_touching_many_attributes_updates_them
     task = Task.first
     previous_starting = task.starting
@@ -178,8 +201,10 @@ class TimestampTest < ActiveRecord::TestCase
     owner = pet.owner
     previously_owner_updated_at = owner.updated_at
 
-    pet.name = "Fluffy the Third"
-    pet.save
+    travel(1.second) do
+      pet.name = "Fluffy the Third"
+      pet.save
+    end
 
     assert_not_equal previously_owner_updated_at, pet.owner.updated_at
   end
@@ -189,7 +214,9 @@ class TimestampTest < ActiveRecord::TestCase
     owner = pet.owner
     previously_owner_updated_at = owner.updated_at
 
-    pet.destroy
+    travel(1.second) do
+      pet.destroy
+    end
 
     assert_not_equal previously_owner_updated_at, pet.owner.updated_at
   end
@@ -233,8 +260,10 @@ class TimestampTest < ActiveRecord::TestCase
     owner.update_columns(happy_at: 3.days.ago)
     previously_owner_updated_at = owner.updated_at
 
-    pet.name = "I'm a parrot"
-    pet.save
+    travel(1.second) do
+      pet.name = "I'm a parrot"
+      pet.save
+    end
 
     assert_not_equal previously_owner_updated_at, pet.owner.updated_at
   end
@@ -425,11 +454,22 @@ class TimestampTest < ActiveRecord::TestCase
     toy = Toy.first
     assert_equal [:created_at, :updated_at], toy.send(:all_timestamp_attributes_in_model)
   end
+
+  def test_index_is_created_for_both_timestamps
+    ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+      t.timestamps(:foos, null: true, index: true)
+    end
+
+    indexes = ActiveRecord::Base.connection.indexes('foos')
+    assert_equal ['created_at', 'updated_at'], indexes.flat_map(&:columns).sort
+  ensure
+    ActiveRecord::Base.connection.drop_table(:foos)
+  end
 end
 
 class TimestampsWithoutTransactionTest < ActiveRecord::TestCase
   include DdlHelper
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   class TimestampAttributePost < ActiveRecord::Base
     attr_accessor :created_at, :updated_at
diff --git a/activerecord/test/cases/touch_later_test.rb b/activerecord/test/cases/touch_later_test.rb
new file mode 100644
index 0000000000..7058f4fbe2
--- /dev/null
+++ b/activerecord/test/cases/touch_later_test.rb
@@ -0,0 +1,114 @@
+require 'cases/helper'
+require 'models/invoice'
+require 'models/line_item'
+require 'models/topic'
+require 'models/node'
+require 'models/tree'
+
+class TouchLaterTest < ActiveRecord::TestCase
+  fixtures :nodes, :trees
+
+  def test_touch_laster_raise_if_non_persisted
+    invoice = Invoice.new
+    Invoice.transaction do
+      assert_not invoice.persisted?
+      assert_raises(ActiveRecord::ActiveRecordError) do
+        invoice.touch_later
+      end
+    end
+  end
+
+  def test_touch_later_dont_set_dirty_attributes
+    invoice = Invoice.create!
+    invoice.touch_later
+    assert_not invoice.changed?
+  end
+
+  def test_touch_later_update_the_attributes
+    time = Time.now.utc - 25.days
+    topic = Topic.create!(updated_at: time, created_at: time)
+    assert_equal time.to_i, topic.updated_at.to_i
+    assert_equal time.to_i, topic.created_at.to_i
+
+    Topic.transaction do
+      topic.touch_later(:created_at)
+      assert_not_equal time.to_i, topic.updated_at.to_i
+      assert_not_equal time.to_i, topic.created_at.to_i
+
+      assert_equal time.to_i, topic.reload.updated_at.to_i
+      assert_equal time.to_i, topic.reload.created_at.to_i
+    end
+    assert_not_equal time.to_i, topic.reload.updated_at.to_i
+    assert_not_equal time.to_i, topic.reload.created_at.to_i
+  end
+
+  def test_touch_touches_immediately
+    time = Time.now.utc - 25.days
+    topic = Topic.create!(updated_at: time, created_at: time)
+    assert_equal time.to_i, topic.updated_at.to_i
+    assert_equal time.to_i, topic.created_at.to_i
+
+    Topic.transaction do
+      topic.touch_later(:created_at)
+      topic.touch
+
+      assert_not_equal time, topic.reload.updated_at
+      assert_not_equal time, topic.reload.created_at
+    end
+  end
+
+  def test_touch_later_an_association_dont_autosave_parent
+    time = Time.now.utc - 25.days
+    line_item = LineItem.create!(amount: 1)
+    invoice = Invoice.create!(line_items: [line_item])
+    invoice.touch(time: time)
+
+    Invoice.transaction do
+      line_item.update(amount: 2)
+      assert_equal time.to_i, invoice.reload.updated_at.to_i
+    end
+
+    assert_not_equal time.to_i, invoice.updated_at.to_i
+  end
+
+  def test_touch_touches_immediately_with_a_custom_time
+    time = (Time.now.utc - 25.days).change(nsec: 0)
+    topic = Topic.create!(updated_at: time, created_at: time)
+    assert_equal time, topic.updated_at
+    assert_equal time, topic.created_at
+
+    Topic.transaction do
+      topic.touch_later(:created_at)
+      time = Time.now.utc - 2.days
+      topic.touch(time: time)
+
+      assert_equal time.to_i, topic.reload.updated_at.to_i
+      assert_equal time.to_i, topic.reload.created_at.to_i
+    end
+  end
+
+  def test_touch_later_dont_hit_the_db
+    invoice = Invoice.create!
+    assert_queries(0) do
+      invoice.touch_later
+    end
+  end
+
+  def test_touching_three_deep
+    skip "Pending from #19324"
+
+    previous_tree_updated_at        = trees(:root).updated_at
+    previous_grandparent_updated_at = nodes(:grandparent).updated_at
+    previous_parent_updated_at      = nodes(:parent_a).updated_at
+    previous_child_updated_at       = nodes(:child_one_of_a).updated_at
+
+    travel 5.seconds
+
+    Node.create! parent: nodes(:child_one_of_a), tree: trees(:root)
+
+    assert_not_equal nodes(:child_one_of_a).reload.updated_at, previous_child_updated_at
+    assert_not_equal nodes(:parent_a).reload.updated_at, previous_parent_updated_at
+    assert_not_equal nodes(:grandparent).reload.updated_at, previous_grandparent_updated_at
+    assert_not_equal trees(:root).reload.updated_at, previous_tree_updated_at
+  end
+end
diff --git a/activerecord/test/cases/transaction_callbacks_test.rb b/activerecord/test/cases/transaction_callbacks_test.rb
index 185fc22e98..f2229939c8 100644
--- a/activerecord/test/cases/transaction_callbacks_test.rb
+++ b/activerecord/test/cases/transaction_callbacks_test.rb
@@ -4,7 +4,6 @@ require 'models/pet'
 require 'models/topic'
 
 class TransactionCallbacksTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
   fixtures :topics, :owners, :pets
 
   class ReplyWithCallbacks < ActiveRecord::Base
@@ -200,21 +199,21 @@ class TransactionCallbacksTest < ActiveRecord::TestCase
   end
 
   def test_call_after_rollback_when_commit_fails
-    @first.class.connection.singleton_class.send(:alias_method, :real_method_commit_db_transaction, :commit_db_transaction)
-    begin
-      @first.class.connection.singleton_class.class_eval do
-        def commit_db_transaction; raise "boom!"; end
-      end
+    @first.after_commit_block { |r| r.history << :after_commit }
+    @first.after_rollback_block { |r| r.history << :after_rollback }
 
-      @first.after_commit_block{|r| r.history << :after_commit}
-      @first.after_rollback_block{|r| r.history << :after_rollback}
+    assert_raises RuntimeError do
+      @first.transaction do
+        tx = @first.class.connection.transaction_manager.current_transaction
+        def tx.commit
+          raise
+        end
 
-      assert !@first.save rescue nil
-      assert_equal [:after_rollback], @first.history
-    ensure
-      @first.class.connection.singleton_class.send(:remove_method, :commit_db_transaction)
-      @first.class.connection.singleton_class.send(:alias_method, :commit_db_transaction, :real_method_commit_db_transaction)
+        @first.save
+      end
     end
+
+    assert_equal [:after_rollback], @first.history
   end
 
   def test_only_call_after_rollback_on_records_rolled_back_to_a_savepoint
@@ -368,7 +367,7 @@ class TransactionCallbacksTest < ActiveRecord::TestCase
 end
 
 class CallbacksOnMultipleActionsTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   class TopicWithCallbacksOnMultipleActions < ActiveRecord::Base
     self.table_name = :topics
@@ -377,6 +376,9 @@ class CallbacksOnMultipleActionsTest < ActiveRecord::TestCase
     after_commit(on: [:create, :update]) { |record| record.history << :create_and_update }
     after_commit(on: [:update, :destroy]) { |record| record.history << :update_and_destroy }
 
+    before_commit(if: :save_before_commit_history) { |record| record.history << :before_commit }
+    before_commit(if: :update_title) { |record| record.update(title: "before commit title") }
+
     def clear_history
       @history = []
     end
@@ -384,6 +386,8 @@ class CallbacksOnMultipleActionsTest < ActiveRecord::TestCase
     def history
       @history ||= []
     end
+
+    attr_accessor :save_before_commit_history, :update_title
   end
 
   def test_after_commit_on_multiple_actions
@@ -400,4 +404,81 @@ class CallbacksOnMultipleActionsTest < ActiveRecord::TestCase
     topic.destroy
     assert_equal [:update_and_destroy, :create_and_destroy], topic.history
   end
+
+  def test_before_commit_actions
+    topic = TopicWithCallbacksOnMultipleActions.new
+    topic.save_before_commit_history = true
+    topic.save
+
+    assert_equal [:before_commit, :create_and_update, :create_and_destroy], topic.history
+  end
+
+  def test_before_commit_update_in_same_transaction
+    topic = TopicWithCallbacksOnMultipleActions.new
+    topic.update_title = true
+    topic.save
+
+    assert_equal "before commit title", topic.title
+    assert_equal "before commit title", topic.reload.title
+  end
+end
+
+
+class TransactionEnrollmentCallbacksTest < ActiveRecord::TestCase
+
+  class TopicWithoutTransactionalEnrollmentCallbacks < ActiveRecord::Base
+    self.table_name = :topics
+
+    before_commit_without_transaction_enrollment { |r| r.history << :before_commit }
+    after_commit_without_transaction_enrollment { |r| r.history << :after_commit }
+    after_rollback_without_transaction_enrollment { |r| r.history << :rollback }
+
+    def history
+      @history ||= []
+    end
+  end
+
+  def setup
+    @topic = TopicWithoutTransactionalEnrollmentCallbacks.create!
+  end
+
+  def test_commit_does_not_run_transactions_callbacks_without_enrollment
+    @topic.transaction do
+      @topic.content = 'foo'
+      @topic.save!
+    end
+    assert @topic.history.empty?
+  end
+
+  def test_commit_run_transactions_callbacks_with_explicit_enrollment
+    @topic.transaction do
+      2.times do
+        @topic.content = 'foo'
+        @topic.save!
+      end
+      @topic.class.connection.add_transaction_record(@topic)
+    end
+    assert_equal [:before_commit, :after_commit], @topic.history
+  end
+
+  def test_rollback_does_not_run_transactions_callbacks_without_enrollment
+    @topic.transaction do
+      @topic.content = 'foo'
+      @topic.save!
+      raise ActiveRecord::Rollback
+    end
+    assert @topic.history.empty?
+  end
+
+  def test_rollback_run_transactions_callbacks_with_explicit_enrollment
+    @topic.transaction do
+      2.times do
+        @topic.content = 'foo'
+        @topic.save!
+      end
+      @topic.class.connection.add_transaction_record(@topic)
+      raise ActiveRecord::Rollback
+    end
+    assert_equal [:rollback], @topic.history
+  end
 end
diff --git a/activerecord/test/cases/transaction_isolation_test.rb b/activerecord/test/cases/transaction_isolation_test.rb
index f89c26532d..2f7d208ed2 100644
--- a/activerecord/test/cases/transaction_isolation_test.rb
+++ b/activerecord/test/cases/transaction_isolation_test.rb
@@ -2,7 +2,7 @@ require 'cases/helper'
 
 unless ActiveRecord::Base.connection.supports_transaction_isolation?
   class TransactionIsolationUnsupportedTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     class Tag < ActiveRecord::Base
     end
@@ -17,7 +17,7 @@ end
 
 if ActiveRecord::Base.connection.supports_transaction_isolation?
   class TransactionIsolationTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     class Tag < ActiveRecord::Base
       self.table_name = 'tags'
diff --git a/activerecord/test/cases/transactions_test.rb b/activerecord/test/cases/transactions_test.rb
index d1d8e71c34..ec5bdfd725 100644
--- a/activerecord/test/cases/transactions_test.rb
+++ b/activerecord/test/cases/transactions_test.rb
@@ -9,7 +9,7 @@ require 'models/post'
 require 'models/movie'
 
 class TransactionTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
   fixtures :topics, :developers, :authors, :posts
 
   def setup
@@ -175,13 +175,20 @@ class TransactionTest < ActiveRecord::TestCase
     assert topic.new_record?, "#{topic.inspect} should be new record"
   end
 
+  def test_transaction_state_is_cleared_when_record_is_persisted
+    author = Author.create! name: 'foo'
+    author.name = nil
+    assert_not author.save
+    assert_not author.new_record?
+  end
+
   def test_update_should_rollback_on_failure
     author = Author.find(1)
     posts_count = author.posts.size
     assert posts_count > 0
     status = author.update(name: nil, post_ids: [])
     assert !status
-    assert_equal posts_count, author.posts(true).size
+    assert_equal posts_count, author.posts.reload.size
   end
 
   def test_update_should_rollback_on_failure!
@@ -191,7 +198,7 @@ class TransactionTest < ActiveRecord::TestCase
     assert_raise(ActiveRecord::RecordInvalid) do
       author.update!(name: nil, post_ids: [])
     end
-    assert_equal posts_count, author.posts(true).size
+    assert_equal posts_count, author.posts.reload.size
   end
 
   def test_cancellation_from_returning_false_in_before_filter
@@ -480,13 +487,17 @@ class TransactionTest < ActiveRecord::TestCase
   end
 
   def test_rollback_when_commit_raises
-    Topic.connection.expects(:begin_db_transaction)
-    Topic.connection.expects(:commit_db_transaction).raises('OH NOES')
-    Topic.connection.expects(:rollback_db_transaction)
+    assert_called(Topic.connection, :begin_db_transaction) do
+      Topic.connection.stub(:commit_db_transaction, ->{ raise('OH NOES') }) do
+        assert_called(Topic.connection, :rollback_db_transaction) do
 
-    assert_raise RuntimeError do
-      Topic.transaction do
-        # do nothing
+          e = assert_raise RuntimeError do
+            Topic.transaction do
+              # do nothing
+            end
+          end
+          assert_equal 'OH NOES', e.message
+        end
       end
     end
   end
@@ -584,6 +595,24 @@ class TransactionTest < ActiveRecord::TestCase
     assert_not topic.frozen?
   end
 
+  def test_rollback_of_frozen_records
+    topic = Topic.create.freeze
+    Topic.transaction do
+      topic.destroy
+      raise ActiveRecord::Rollback
+    end
+    assert topic.frozen?, 'frozen'
+  end
+
+  def test_rollback_for_freshly_persisted_records
+    topic = Topic.create
+    Topic.transaction do
+      topic.destroy
+      raise ActiveRecord::Rollback
+    end
+    assert topic.persisted?, 'persisted'
+  end
+
   def test_sqlite_add_column_in_transaction
     return true unless current_adapter?(:SQLite3Adapter)
 
@@ -668,7 +697,7 @@ class TransactionTest < ActiveRecord::TestCase
       end
     end
   ensure
-    connection.execute("DROP TABLE IF EXISTS transaction_without_primary_keys")
+    connection.drop_table 'transaction_without_primary_keys', if_exists: true
   end
 
   private
@@ -685,7 +714,7 @@ class TransactionTest < ActiveRecord::TestCase
 end
 
 class TransactionsWithTransactionalFixturesTest < ActiveRecord::TestCase
-  self.use_transactional_fixtures = true
+  self.use_transactional_tests = true
   fixtures :topics
 
   def test_automatic_savepoint_in_outer_transaction
diff --git a/activerecord/test/cases/type/adapter_specific_registry_test.rb b/activerecord/test/cases/type/adapter_specific_registry_test.rb
new file mode 100644
index 0000000000..8b836b4793
--- /dev/null
+++ b/activerecord/test/cases/type/adapter_specific_registry_test.rb
@@ -0,0 +1,133 @@
+require "cases/helper"
+
+module ActiveRecord
+  class AdapterSpecificRegistryTest < ActiveRecord::TestCase
+    test "a class can be registered for a symbol" do
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, ::String)
+      registry.register(:bar, ::Array)
+
+      assert_equal "", registry.lookup(:foo)
+      assert_equal [], registry.lookup(:bar)
+    end
+
+    test "a block can be registered" do
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo) do |*args|
+        [*args, "block for foo"]
+      end
+      registry.register(:bar) do |*args|
+        [*args, "block for bar"]
+      end
+
+      assert_equal [:foo, 1, "block for foo"], registry.lookup(:foo, 1)
+      assert_equal [:foo, 2, "block for foo"], registry.lookup(:foo, 2)
+      assert_equal [:bar, 1, 2, 3, "block for bar"], registry.lookup(:bar, 1, 2, 3)
+    end
+
+    test "filtering by adapter" do
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, String, adapter: :sqlite3)
+      registry.register(:foo, Array, adapter: :postgresql)
+
+      assert_equal "", registry.lookup(:foo, adapter: :sqlite3)
+      assert_equal [], registry.lookup(:foo, adapter: :postgresql)
+    end
+
+    test "an error is raised if both a generic and adapter specific type match" do
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, String)
+      registry.register(:foo, Array, adapter: :postgresql)
+
+      assert_raises TypeConflictError do
+        registry.lookup(:foo, adapter: :postgresql)
+      end
+      assert_equal "", registry.lookup(:foo, adapter: :sqlite3)
+    end
+
+    test "a generic type can explicitly override an adapter specific type" do
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, String, override: true)
+      registry.register(:foo, Array, adapter: :postgresql)
+
+      assert_equal "", registry.lookup(:foo, adapter: :postgresql)
+      assert_equal "", registry.lookup(:foo, adapter: :sqlite3)
+    end
+
+    test "a generic type can explicitly allow an adapter type to be used instead" do
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, String, override: false)
+      registry.register(:foo, Array, adapter: :postgresql)
+
+      assert_equal [], registry.lookup(:foo, adapter: :postgresql)
+      assert_equal "", registry.lookup(:foo, adapter: :sqlite3)
+    end
+
+    test "a reasonable error is given when no type is found" do
+      registry = Type::AdapterSpecificRegistry.new
+
+      e = assert_raises(ArgumentError) do
+        registry.lookup(:foo)
+      end
+
+      assert_equal "Unknown type :foo", e.message
+    end
+
+    test "construct args are passed to the type" do
+      type = Struct.new(:args)
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, type)
+
+      assert_equal type.new, registry.lookup(:foo)
+      assert_equal type.new(:ordered_arg), registry.lookup(:foo, :ordered_arg)
+      assert_equal type.new(keyword: :arg), registry.lookup(:foo, keyword: :arg)
+      assert_equal type.new(keyword: :arg), registry.lookup(:foo, keyword: :arg, adapter: :postgresql)
+    end
+
+    test "registering a modifier" do
+      decoration = Struct.new(:value)
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, String)
+      registry.register(:bar, Hash)
+      registry.add_modifier({ array: true }, decoration)
+
+      assert_equal decoration.new(""), registry.lookup(:foo, array: true)
+      assert_equal decoration.new({}), registry.lookup(:bar, array: true)
+      assert_equal "", registry.lookup(:foo)
+    end
+
+    test "registering multiple modifiers" do
+      decoration = Struct.new(:value)
+      other_decoration = Struct.new(:value)
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, String)
+      registry.add_modifier({ array: true }, decoration)
+      registry.add_modifier({ range: true }, other_decoration)
+
+      assert_equal "", registry.lookup(:foo)
+      assert_equal decoration.new(""), registry.lookup(:foo, array: true)
+      assert_equal other_decoration.new(""), registry.lookup(:foo, range: true)
+      assert_equal(
+        decoration.new(other_decoration.new("")),
+        registry.lookup(:foo, array: true, range: true)
+      )
+    end
+
+    test "registering adapter specific modifiers" do
+      decoration = Struct.new(:value)
+      type = Struct.new(:args)
+      registry = Type::AdapterSpecificRegistry.new
+      registry.register(:foo, type)
+      registry.add_modifier({ array: true }, decoration, adapter: :postgresql)
+
+      assert_equal(
+        decoration.new(type.new(keyword: :arg)),
+        registry.lookup(:foo, array: true, adapter: :postgresql, keyword: :arg)
+      )
+      assert_equal(
+        type.new(array: true),
+        registry.lookup(:foo, array: true, adapter: :sqlite3)
+      )
+    end
+  end
+end
diff --git a/activerecord/test/cases/type/date_time_test.rb b/activerecord/test/cases/type/date_time_test.rb
new file mode 100644
index 0000000000..bc4900e1c2
--- /dev/null
+++ b/activerecord/test/cases/type/date_time_test.rb
@@ -0,0 +1,14 @@
+require "cases/helper"
+require "models/task"
+
+module ActiveRecord
+  module Type
+    class IntegerTest < ActiveRecord::TestCase
+      def test_datetime_seconds_precision_applied_to_timestamp
+        skip "This test is invalid if subsecond precision isn't supported" unless subsecond_precision_supported?
+        p = Task.create!(starting: ::Time.now)
+        assert_equal p.starting.usec, p.reload.starting.usec
+      end
+    end
+  end
+end
diff --git a/activerecord/test/cases/type/integer_test.rb b/activerecord/test/cases/type/integer_test.rb
index ff956b7680..c0932d5357 100644
--- a/activerecord/test/cases/type/integer_test.rb
+++ b/activerecord/test/cases/type/integer_test.rb
@@ -4,110 +4,23 @@ require "models/company"
 module ActiveRecord
   module Type
     class IntegerTest < ActiveRecord::TestCase
-      test "simple values" do
-        type = Type::Integer.new
-        assert_equal 1, type.type_cast_from_user(1)
-        assert_equal 1, type.type_cast_from_user('1')
-        assert_equal 1, type.type_cast_from_user('1ignore')
-        assert_equal 0, type.type_cast_from_user('bad1')
-        assert_equal 0, type.type_cast_from_user('bad')
-        assert_equal 1, type.type_cast_from_user(1.7)
-        assert_equal 0, type.type_cast_from_user(false)
-        assert_equal 1, type.type_cast_from_user(true)
-        assert_nil type.type_cast_from_user(nil)
-      end
-
-      test "random objects cast to nil" do
-        type = Type::Integer.new
-        assert_nil type.type_cast_from_user([1,2])
-        assert_nil type.type_cast_from_user({1 => 2})
-        assert_nil type.type_cast_from_user((1..2))
-      end
-
       test "casting ActiveRecord models" do
         type = Type::Integer.new
         firm = Firm.create(:name => 'Apple')
-        assert_nil type.type_cast_from_user(firm)
-      end
-
-      test "casting objects without to_i" do
-        type = Type::Integer.new
-        assert_nil type.type_cast_from_user(::Object.new)
-      end
-
-      test "casting nan and infinity" do
-        type = Type::Integer.new
-        assert_nil type.type_cast_from_user(::Float::NAN)
-        assert_nil type.type_cast_from_user(1.0/0.0)
-      end
-
-      test "casting booleans for database" do
-        type = Type::Integer.new
-        assert_equal 1, type.type_cast_for_database(true)
-        assert_equal 0, type.type_cast_for_database(false)
-      end
-
-      test "changed?" do
-        type = Type::Integer.new
-
-        assert type.changed?(5, 5, '5wibble')
-        assert_not type.changed?(5, 5, '5')
-        assert_not type.changed?(5, 5, '5.0')
-        assert_not type.changed?(-5, -5, '-5')
-        assert_not type.changed?(-5, -5, '-5.0')
-        assert_not type.changed?(nil, nil, nil)
+        assert_nil type.cast(firm)
       end
 
-      test "values below int min value are out of range" do
-        assert_raises(::RangeError) do
-          Integer.new.type_cast_from_user("-2147483649")
+      test "values which are out of range can be re-assigned" do
+        klass = Class.new(ActiveRecord::Base) do
+          self.table_name = 'posts'
+          attribute :foo, :integer
         end
-      end
-
-      test "values above int max value are out of range" do
-        assert_raises(::RangeError) do
-          Integer.new.type_cast_from_user("2147483648")
-        end
-      end
-
-      test "very small numbers are out of range" do
-        assert_raises(::RangeError) do
-          Integer.new.type_cast_from_user("-9999999999999999999999999999999")
-        end
-      end
-
-      test "very large numbers are out of range" do
-        assert_raises(::RangeError) do
-          Integer.new.type_cast_from_user("9999999999999999999999999999999")
-        end
-      end
+        model = klass.new
 
-      test "normal numbers are in range" do
-        type = Integer.new
-        assert_equal(0, type.type_cast_from_user("0"))
-        assert_equal(-1, type.type_cast_from_user("-1"))
-        assert_equal(1, type.type_cast_from_user("1"))
-      end
+        model.foo = 2147483648
+        model.foo = 1
 
-      test "int max value is in range" do
-        assert_equal(2147483647, Integer.new.type_cast_from_user("2147483647"))
-      end
-
-      test "int min value is in range" do
-        assert_equal(-2147483648, Integer.new.type_cast_from_user("-2147483648"))
-      end
-
-      test "columns with a larger limit have larger ranges" do
-        type = Integer.new(limit: 8)
-
-        assert_equal(9223372036854775807, type.type_cast_from_user("9223372036854775807"))
-        assert_equal(-9223372036854775808, type.type_cast_from_user("-9223372036854775808"))
-        assert_raises(::RangeError) do
-          type.type_cast_from_user("-9999999999999999999999999999999")
-        end
-        assert_raises(::RangeError) do
-          type.type_cast_from_user("9999999999999999999999999999999")
-        end
+        assert_equal 1, model.foo
       end
     end
   end
diff --git a/activerecord/test/cases/type/string_test.rb b/activerecord/test/cases/type/string_test.rb
index 4d78f287f1..6fe6d46711 100644
--- a/activerecord/test/cases/type/string_test.rb
+++ b/activerecord/test/cases/type/string_test.rb
@@ -2,20 +2,6 @@ require 'cases/helper'
 
 module ActiveRecord
   class StringTypeTest < ActiveRecord::TestCase
-    test "type casting" do
-      type = Type::String.new
-      assert_equal "t", type.type_cast_from_user(true)
-      assert_equal "f", type.type_cast_from_user(false)
-      assert_equal "123", type.type_cast_from_user(123)
-    end
-
-    test "values are duped coming out" do
-      s = "foo"
-      type = Type::String.new
-      assert_not_same s, type.type_cast_from_user(s)
-      assert_not_same s, type.type_cast_from_database(s)
-    end
-
     test "string mutations are detected" do
       klass = Class.new(Base)
       klass.table_name = 'authors'
diff --git a/activerecord/test/cases/type_test.rb b/activerecord/test/cases/type_test.rb
new file mode 100644
index 0000000000..d45a9b3141
--- /dev/null
+++ b/activerecord/test/cases/type_test.rb
@@ -0,0 +1,39 @@
+require "cases/helper"
+
+class TypeTest < ActiveRecord::TestCase
+  setup do
+    @old_registry = ActiveRecord::Type.registry
+    ActiveRecord::Type.registry = ActiveRecord::Type::AdapterSpecificRegistry.new
+  end
+
+  teardown do
+    ActiveRecord::Type.registry = @old_registry
+  end
+
+  test "registering a new type" do
+    type = Struct.new(:args)
+    ActiveRecord::Type.register(:foo, type)
+
+    assert_equal type.new(:arg), ActiveRecord::Type.lookup(:foo, :arg)
+  end
+
+  test "looking up a type for a specific adapter" do
+    type = Struct.new(:args)
+    pgtype = Struct.new(:args)
+    ActiveRecord::Type.register(:foo, type, override: false)
+    ActiveRecord::Type.register(:foo, pgtype, adapter: :postgresql)
+
+    assert_equal type.new, ActiveRecord::Type.lookup(:foo, adapter: :sqlite)
+    assert_equal pgtype.new, ActiveRecord::Type.lookup(:foo, adapter: :postgresql)
+  end
+
+  test "lookup defaults to the current adapter" do
+    current_adapter = ActiveRecord::Base.connection.adapter_name.downcase.to_sym
+    type = Struct.new(:args)
+    adapter_type = Struct.new(:args)
+    ActiveRecord::Type.register(:foo, type, override: false)
+    ActiveRecord::Type.register(:foo, adapter_type, adapter: current_adapter)
+
+    assert_equal adapter_type.new, ActiveRecord::Type.lookup(:foo)
+  end
+end
diff --git a/activerecord/test/cases/types_test.rb b/activerecord/test/cases/types_test.rb
index 73e92addfe..81fcf04a27 100644
--- a/activerecord/test/cases/types_test.rb
+++ b/activerecord/test/cases/types_test.rb
@@ -3,119 +3,21 @@ require "cases/helper"
 module ActiveRecord
   module ConnectionAdapters
     class TypesTest < ActiveRecord::TestCase
-      def test_type_cast_boolean
-        type = Type::Boolean.new
-        assert type.type_cast_from_user('').nil?
-        assert type.type_cast_from_user(nil).nil?
-
-        assert type.type_cast_from_user(true)
-        assert type.type_cast_from_user(1)
-        assert type.type_cast_from_user('1')
-        assert type.type_cast_from_user('t')
-        assert type.type_cast_from_user('T')
-        assert type.type_cast_from_user('true')
-        assert type.type_cast_from_user('TRUE')
-        assert type.type_cast_from_user('on')
-        assert type.type_cast_from_user('ON')
-        assert type.type_cast_from_user(' ')
-        assert type.type_cast_from_user("\u3000\r\n")
-        assert type.type_cast_from_user("\u0000")
-        assert type.type_cast_from_user('SOMETHING RANDOM')
-
-        # explicitly check for false vs nil
-        assert_equal false, type.type_cast_from_user(false)
-        assert_equal false, type.type_cast_from_user(0)
-        assert_equal false, type.type_cast_from_user('0')
-        assert_equal false, type.type_cast_from_user('f')
-        assert_equal false, type.type_cast_from_user('F')
-        assert_equal false, type.type_cast_from_user('false')
-        assert_equal false, type.type_cast_from_user('FALSE')
-        assert_equal false, type.type_cast_from_user('off')
-        assert_equal false, type.type_cast_from_user('OFF')
-      end
-
-      def test_type_cast_float
-        type = Type::Float.new
-        assert_equal 1.0, type.type_cast_from_user("1")
-      end
-
-      def test_changing_float
-        type = Type::Float.new
-
-        assert type.changed?(5.0, 5.0, '5wibble')
-        assert_not type.changed?(5.0, 5.0, '5')
-        assert_not type.changed?(5.0, 5.0, '5.0')
-        assert_not type.changed?(nil, nil, nil)
-      end
-
-      def test_type_cast_binary
-        type = Type::Binary.new
-        assert_equal nil, type.type_cast_from_user(nil)
-        assert_equal "1", type.type_cast_from_user("1")
-        assert_equal 1, type.type_cast_from_user(1)
-      end
-
-      def test_type_cast_time
-        type = Type::Time.new
-        assert_equal nil, type.type_cast_from_user(nil)
-        assert_equal nil, type.type_cast_from_user('')
-        assert_equal nil, type.type_cast_from_user('ABC')
-
-        time_string = Time.now.utc.strftime("%T")
-        assert_equal time_string, type.type_cast_from_user(time_string).strftime("%T")
-      end
-
-      def test_type_cast_datetime_and_timestamp
-        type = Type::DateTime.new
-        assert_equal nil, type.type_cast_from_user(nil)
-        assert_equal nil, type.type_cast_from_user('')
-        assert_equal nil, type.type_cast_from_user('  ')
-        assert_equal nil, type.type_cast_from_user('ABC')
-
-        datetime_string = Time.now.utc.strftime("%FT%T")
-        assert_equal datetime_string, type.type_cast_from_user(datetime_string).strftime("%FT%T")
-      end
-
-      def test_type_cast_date
-        type = Type::Date.new
-        assert_equal nil, type.type_cast_from_user(nil)
-        assert_equal nil, type.type_cast_from_user('')
-        assert_equal nil, type.type_cast_from_user(' ')
-        assert_equal nil, type.type_cast_from_user('ABC')
-
-        date_string = Time.now.utc.strftime("%F")
-        assert_equal date_string, type.type_cast_from_user(date_string).strftime("%F")
-      end
-
-      def test_type_cast_duration_to_integer
-        type = Type::Integer.new
-        assert_equal 1800, type.type_cast_from_user(30.minutes)
-        assert_equal 7200, type.type_cast_from_user(2.hours)
-      end
-
-      def test_string_to_time_with_timezone
-        [:utc, :local].each do |zone|
-          with_timezone_config default: zone do
-            type = Type::DateTime.new
-            assert_equal Time.utc(2013, 9, 4, 0, 0, 0), type.type_cast_from_user("Wed, 04 Sep 2013 03:00:00 EAT")
-          end
+      def test_attributes_which_are_invalid_for_database_can_still_be_reassigned
+        type_which_cannot_go_to_the_database = Type::Value.new
+        def type_which_cannot_go_to_the_database.serialize(*)
+          raise
         end
-      end
-
-      def test_type_equality
-        assert_equal Type::Value.new, Type::Value.new
-        assert_not_equal Type::Value.new, Type::Integer.new
-        assert_not_equal Type::Value.new(precision: 1), Type::Value.new(precision: 2)
-      end
+        klass = Class.new(ActiveRecord::Base) do
+          self.table_name = 'posts'
+          attribute :foo, type_which_cannot_go_to_the_database
+        end
+        model = klass.new
 
-      if current_adapter?(:SQLite3Adapter)
-        def test_binary_encoding
-          type = SQLite3Binary.new
-          utf8_string = "a string".encode(Encoding::UTF_8)
-          type_cast = type.type_cast_from_user(utf8_string)
+        model.foo = "foo"
+        model.foo = "bar"
 
-          assert_equal Encoding::ASCII_8BIT, type_cast.encoding
-        end
+        assert_equal "bar", model.foo
       end
     end
   end
diff --git a/activerecord/test/cases/unconnected_test.rb b/activerecord/test/cases/unconnected_test.rb
index afb893a52c..b210584644 100644
--- a/activerecord/test/cases/unconnected_test.rb
+++ b/activerecord/test/cases/unconnected_test.rb
@@ -4,7 +4,7 @@ class TestRecord < ActiveRecord::Base
 end
 
 class TestUnconnectedAdapter < ActiveRecord::TestCase
-  self.use_transactional_fixtures = false
+  self.use_transactional_tests = false
 
   def setup
     @underlying = ActiveRecord::Base.connection
diff --git a/activerecord/test/cases/validations/absence_validation_test.rb b/activerecord/test/cases/validations/absence_validation_test.rb
new file mode 100644
index 0000000000..dd43ee358c
--- /dev/null
+++ b/activerecord/test/cases/validations/absence_validation_test.rb
@@ -0,0 +1,75 @@
+require "cases/helper"
+require 'models/face'
+require 'models/interest'
+require 'models/man'
+require 'models/topic'
+
+class AbsenceValidationTest < ActiveRecord::TestCase
+  def test_non_association
+    boy_klass = Class.new(Man) do
+      def self.name; "Boy" end
+      validates_absence_of :name
+    end
+
+    assert boy_klass.new.valid?
+    assert_not boy_klass.new(name: "Alex").valid?
+  end
+
+  def test_has_one_marked_for_destruction
+    boy_klass = Class.new(Man) do
+      def self.name; "Boy" end
+      validates_absence_of :face
+    end
+
+    boy = boy_klass.new(face: Face.new)
+    assert_not boy.valid?, "should not be valid if has_one association is present"
+    assert_equal 1, boy.errors[:face].size, "should only add one error"
+
+    boy.face.mark_for_destruction
+    assert boy.valid?, "should be valid if association is marked for destruction"
+  end
+
+  def test_has_many_marked_for_destruction
+    boy_klass = Class.new(Man) do
+      def self.name; "Boy" end
+      validates_absence_of :interests
+    end
+    boy = boy_klass.new
+    boy.interests << [i1 = Interest.new, i2 = Interest.new]
+    assert_not boy.valid?, "should not be valid if has_many association is present"
+
+    i1.mark_for_destruction
+    assert_not boy.valid?, "should not be valid if has_many association is present"
+
+    i2.mark_for_destruction
+    assert boy.valid?
+  end
+
+  def test_does_not_call_to_a_on_associations
+    boy_klass = Class.new(Man) do
+      def self.name; "Boy" end
+      validates_absence_of :face
+    end
+
+    face_with_to_a = Face.new
+    def face_with_to_a.to_a; ['(/)', '(\)']; end
+
+    assert_nothing_raised { boy_klass.new(face: face_with_to_a).valid? }
+  end
+
+  def test_does_not_validate_if_parent_record_is_validate_false
+    repair_validations(Interest) do
+      Interest.validates_absence_of(:topic)
+      interest = Interest.new(topic: Topic.new(title: "Math"))
+      interest.save!(validate: false)
+      assert interest.persisted?
+
+      man = Man.new(interest_ids: [interest.id])
+      man.save!
+
+      assert_equal man.interests.size, 1
+      assert interest.valid?
+      assert man.valid?
+    end
+  end
+end
diff --git a/activerecord/test/cases/validations/association_validation_test.rb b/activerecord/test/cases/validations/association_validation_test.rb
index e4edc437e6..bff5ffa65e 100644
--- a/activerecord/test/cases/validations/association_validation_test.rb
+++ b/activerecord/test/cases/validations/association_validation_test.rb
@@ -50,7 +50,7 @@ class AssociationValidationTest < ActiveRecord::TestCase
     Topic.validates_presence_of :content
     r = Reply.create("title" => "A reply", "content" => "with content!")
     r.topic = Topic.create("title" => "uhohuhoh")
-    assert !r.valid?
+    assert_not_operator r, :valid?
     assert_equal ["This string contains 'single' and \"double\" quotes"], r.errors[:topic]
   end
 
@@ -82,5 +82,4 @@ class AssociationValidationTest < ActiveRecord::TestCase
       assert interest.valid?, "Expected interest to be valid, but was not. Interest should have a man object associated"
     end
   end
-
 end
diff --git a/activerecord/test/cases/validations/i18n_validation_test.rb b/activerecord/test/cases/validations/i18n_validation_test.rb
index 268d7914b5..981239c4d6 100644
--- a/activerecord/test/cases/validations/i18n_validation_test.rb
+++ b/activerecord/test/cases/validations/i18n_validation_test.rb
@@ -53,8 +53,9 @@ class I18nValidationTest < ActiveRecord::TestCase
     test "validates_uniqueness_of on generated message #{name}" do
       Topic.validates_uniqueness_of :title, validation_options
       @topic.title = unique_topic.title
-      @topic.errors.expects(:generate_message).with(:title, :taken, generate_message_options.merge(:value => 'unique!'))
-      @topic.valid?
+      assert_called_with(@topic.errors, :generate_message, [:title, :taken, generate_message_options.merge(:value => 'unique!')]) do
+        @topic.valid?
+      end
     end
   end
 
@@ -63,8 +64,9 @@ class I18nValidationTest < ActiveRecord::TestCase
   COMMON_CASES.each do |name, validation_options, generate_message_options|
     test "validates_associated on generated message #{name}" do
       Topic.validates_associated :replies, validation_options
-      replied_topic.errors.expects(:generate_message).with(:replies, :invalid, generate_message_options.merge(:value => replied_topic.replies))
-      replied_topic.save
+      assert_called_with(replied_topic.errors, :generate_message, [:replies, :invalid, generate_message_options.merge(:value => replied_topic.replies)]) do
+        replied_topic.save
+      end
     end
   end
 
diff --git a/activerecord/test/cases/validations/length_validation_test.rb b/activerecord/test/cases/validations/length_validation_test.rb
index 2c0e282761..c5d8f8895c 100644
--- a/activerecord/test/cases/validations/length_validation_test.rb
+++ b/activerecord/test/cases/validations/length_validation_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'models/owner'
 require 'models/pet'
@@ -6,49 +5,49 @@ require 'models/person'
 
 class LengthValidationTest < ActiveRecord::TestCase
   fixtures :owners
-  repair_validations(Owner)
 
-  def test_validates_size_of_association
-    repair_validations Owner do
-      assert_nothing_raised { Owner.validates_size_of :pets, :minimum => 1 }
-      o = Owner.new('name' => 'nopets')
-      assert !o.save
-      assert o.errors[:pets].any?
-      o.pets.build('name' => 'apet')
-      assert o.valid?
+  setup do
+    @owner = Class.new(Owner) do
+      def self.name; 'Owner'; end
     end
   end
 
+
+  def test_validates_size_of_association
+    assert_nothing_raised { @owner.validates_size_of :pets, minimum: 1 }
+    o = @owner.new('name' => 'nopets')
+    assert !o.save
+    assert o.errors[:pets].any?
+    o.pets.build('name' => 'apet')
+    assert o.valid?
+  end
+
   def test_validates_size_of_association_using_within
-    repair_validations Owner do
-      assert_nothing_raised { Owner.validates_size_of :pets, :within => 1..2 }
-      o = Owner.new('name' => 'nopets')
-      assert !o.save
-      assert o.errors[:pets].any?
+    assert_nothing_raised { @owner.validates_size_of :pets, within: 1..2 }
+    o = @owner.new('name' => 'nopets')
+    assert !o.save
+    assert o.errors[:pets].any?
 
-      o.pets.build('name' => 'apet')
-      assert o.valid?
+    o.pets.build('name' => 'apet')
+    assert o.valid?
 
-      2.times { o.pets.build('name' => 'apet') }
-      assert !o.save
-      assert o.errors[:pets].any?
-    end
+    2.times { o.pets.build('name' => 'apet') }
+    assert !o.save
+    assert o.errors[:pets].any?
   end
 
   def test_validates_size_of_association_utf8
-    repair_validations Owner do
-      assert_nothing_raised { Owner.validates_size_of :pets, :minimum => 1 }
-      o = Owner.new('name' => 'あいうえおかきくけこ')
-      assert !o.save
-      assert o.errors[:pets].any?
-      o.pets.build('name' => 'あいうえおかきくけこ')
-      assert o.valid?
-    end
+    @owner.validates_size_of :pets, minimum: 1
+    o = @owner.new('name' => 'あいうえおかきくけこ')
+    assert !o.save
+    assert o.errors[:pets].any?
+    o.pets.build('name' => 'あいうえおかきくけこ')
+    assert o.valid?
   end
 
-  def test_validates_size_of_reprects_records_marked_for_destruction
-    assert_nothing_raised { Owner.validates_size_of :pets, minimum: 1 }
-    owner = Owner.new
+  def test_validates_size_of_respects_records_marked_for_destruction
+    @owner.validates_size_of :pets, minimum: 1
+    owner = @owner.new
     assert_not owner.save
     assert owner.errors[:pets].any?
     pet = owner.pets.build
@@ -62,4 +61,17 @@ class LengthValidationTest < ActiveRecord::TestCase
     assert_equal pet_count, Pet.count
   end
 
+  def test_does_not_validate_length_of_if_parent_record_is_validate_false
+    @owner.validates_length_of :name, minimum: 1
+    owner = @owner.new
+    owner.save!(validate: false)
+    assert owner.persisted?
+
+    pet = Pet.new(owner_id: owner.id)
+    pet.save!
+
+    assert_equal owner.pets.size, 1
+    assert owner.valid?
+    assert pet.valid?
+  end
 end
diff --git a/activerecord/test/cases/validations/presence_validation_test.rb b/activerecord/test/cases/validations/presence_validation_test.rb
index 4f38849131..6f8ad06ab6 100644
--- a/activerecord/test/cases/validations/presence_validation_test.rb
+++ b/activerecord/test/cases/validations/presence_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/man'
 require 'models/face'
@@ -65,4 +64,20 @@ class PresenceValidationTest < ActiveRecord::TestCase
 
     assert_nothing_raised { s.valid? }
   end
+
+  def test_does_not_validate_presence_of_if_parent_record_is_validate_false
+    repair_validations(Interest) do
+      Interest.validates_presence_of(:topic)
+      interest = Interest.new
+      interest.save!(validate: false)
+      assert interest.persisted?
+
+      man = Man.new(interest_ids: [interest.id])
+      man.save!
+
+      assert_equal man.interests.size, 1
+      assert interest.valid?
+      assert man.valid?
+    end
+  end
 end
diff --git a/activerecord/test/cases/validations/uniqueness_validation_test.rb b/activerecord/test/cases/validations/uniqueness_validation_test.rb
index 524f59876e..7502a55391 100644
--- a/activerecord/test/cases/validations/uniqueness_validation_test.rb
+++ b/activerecord/test/cases/validations/uniqueness_validation_test.rb
@@ -1,10 +1,10 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/topic'
 require 'models/reply'
 require 'models/warehouse_thing'
 require 'models/guid'
 require 'models/event'
+require 'models/dashboard'
 
 class Wizard < ActiveRecord::Base
   self.abstract_class = true
@@ -35,7 +35,22 @@ class TopicWithUniqEvent < Topic
   validates :event, uniqueness: true
 end
 
+class BigIntTest < ActiveRecord::Base
+  INT_MAX_VALUE = 2147483647
+  self.table_name = 'cars'
+  validates :engines_count, uniqueness: true, inclusion: { in: 0..INT_MAX_VALUE }
+end
+
+class BigIntReverseTest < ActiveRecord::Base
+  INT_MAX_VALUE = 2147483647
+  self.table_name = 'cars'
+  validates :engines_count, inclusion: { in: 0..INT_MAX_VALUE }
+  validates :engines_count, uniqueness: true
+end
+
 class UniquenessValidationTest < ActiveRecord::TestCase
+  INT_MAX_VALUE = 2147483647
+
   fixtures :topics, 'warehouse-things'
 
   repair_validations(Topic, Reply)
@@ -87,6 +102,16 @@ class UniquenessValidationTest < ActiveRecord::TestCase
     assert t2.errors[:title]
   end
 
+  def test_validate_uniqueness_when_integer_out_of_range
+    entry = BigIntTest.create(engines_count: INT_MAX_VALUE + 1)
+    assert_equal entry.errors[:engines_count], ['is not included in the list']
+  end
+
+  def test_validate_uniqueness_when_integer_out_of_range_show_order_does_not_matter
+    entry = BigIntReverseTest.create(engines_count: INT_MAX_VALUE + 1)
+    assert_equal entry.errors[:engines_count], ['is not included in the list']
+  end
+
   def test_validates_uniqueness_with_newline_chars
     Topic.validates_uniqueness_of(:title, :case_sensitive => false)
 
@@ -386,4 +411,62 @@ class UniquenessValidationTest < ActiveRecord::TestCase
     topic = TopicWithUniqEvent.new
     assert topic.valid?
   end
+
+  def test_does_not_validate_uniqueness_of_if_parent_record_is_validate_false
+    Reply.validates_uniqueness_of(:content)
+
+    Reply.create!(content: "Topic Title")
+
+    reply = Reply.new(content: "Topic Title")
+    reply.save!(validate: false)
+    assert reply.persisted?
+
+    topic = Topic.new(reply_ids: [reply.id])
+    topic.save!
+
+    assert_equal topic.replies.size, 1
+    assert reply.valid?
+    assert topic.valid?
+  end
+
+  def test_validate_uniqueness_of_custom_primary_key
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = "keyboards"
+      self.primary_key = :key_number
+
+      validates_uniqueness_of :key_number
+
+      def self.name
+        "Keyboard"
+      end
+    end
+
+    klass.create!(key_number: 10)
+    key2 = klass.create!(key_number: 11)
+
+    key2.key_number = 10
+    assert_not key2.valid?
+  end
+
+  def test_validate_uniqueness_without_primary_key
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = "dashboards"
+
+      validates_uniqueness_of :dashboard_id
+
+      def self.name; "Dashboard" end
+    end
+
+    abc = klass.create!(dashboard_id: "abc")
+    assert klass.new(dashboard_id: "xyz").valid?
+    assert_not klass.new(dashboard_id: "abc").valid?
+
+    abc.dashboard_id = "def"
+
+    e = assert_raises ActiveRecord::UnknownPrimaryKey do
+      abc.save!
+    end
+    assert_match(/\AUnknown primary key for table dashboards in model/, e.message)
+    assert_match(/Can not validate uniqueness for persisted record without primary key.\z/, e.message)
+  end
 end
diff --git a/activerecord/test/cases/validations_test.rb b/activerecord/test/cases/validations_test.rb
index 959c58aa85..d04f4f7ce7 100644
--- a/activerecord/test/cases/validations_test.rb
+++ b/activerecord/test/cases/validations_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/topic'
 require 'models/reply'
@@ -53,6 +52,13 @@ class ValidationsTest < ActiveRecord::TestCase
     assert r.valid?(:special_case)
   end
 
+  def test_invalid_using_multiple_contexts
+    r = WrongReply.new(:title => 'Wrong Create')
+    assert r.invalid?([:special_case, :create])
+    assert_equal "Invalid", r.errors[:author_name].join
+    assert_equal "is Wrong Create", r.errors[:title].join
+  end
+
   def test_validate
     r = WrongReply.new
 
@@ -151,7 +157,7 @@ class ValidationsTest < ActiveRecord::TestCase
 
   def test_numericality_validation_with_mutation
     Topic.class_eval do
-      attribute :wibble, ActiveRecord::Type::String.new
+      attribute :wibble, :string
       validates_numericality_of :wibble, only_integer: true
     end
 
@@ -162,4 +168,15 @@ class ValidationsTest < ActiveRecord::TestCase
   ensure
     Topic.reset_column_information
   end
+
+  def test_acceptance_validator_doesnt_require_db_connection
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = 'posts'
+    end
+    klass.reset_column_information
+
+    assert_no_queries do
+      klass.validates_acceptance_of(:foo)
+    end
+  end
 end
diff --git a/activerecord/test/cases/view_test.rb b/activerecord/test/cases/view_test.rb
index 3aed90ba36..e80d8bd584 100644
--- a/activerecord/test/cases/view_test.rb
+++ b/activerecord/test/cases/view_test.rb
@@ -1,7 +1,9 @@
 require "cases/helper"
 require "models/book"
+require "support/schema_dumping_helper"
 
 module ViewBehavior
+  include SchemaDumpingHelper
   extend ActiveSupport::Concern
 
   included do
@@ -31,11 +33,26 @@ module ViewBehavior
     assert_equal ["Ruby for Rails"], books.map(&:name)
   end
 
+  def test_views
+    assert_equal [Ebook.table_name], @connection.views
+  end
+
+  def test_view_exists
+    view_name = Ebook.table_name
+    assert @connection.view_exists?(view_name), "'#{view_name}' view should exist"
+  end
+
   def test_table_exists
     view_name = Ebook.table_name
+    # TODO: switch this assertion around once we changed #tables to not return views.
     assert @connection.table_exists?(view_name), "'#{view_name}' table should exist"
   end
 
+  def test_views_ara_valid_data_sources
+    view_name = Ebook.table_name
+    assert @connection.data_source_exists?(view_name), "'#{view_name}' should be a data source"
+  end
+
   def test_column_definitions
     assert_equal([["id", :integer],
                   ["name", :string],
@@ -53,6 +70,11 @@ module ViewBehavior
     end
     assert_nil model.primary_key
   end
+
+  def test_does_not_dump_view_as_table
+    schema = dump_table_schema "ebooks"
+    assert_no_match %r{create_table "ebooks"}, schema
+  end
 end
 
 if ActiveRecord::Base.connection.supports_views?
@@ -70,6 +92,7 @@ class ViewWithPrimaryKeyTest < ActiveRecord::TestCase
 end
 
 class ViewWithoutPrimaryKeyTest < ActiveRecord::TestCase
+  include SchemaDumpingHelper
   fixtures :books
 
   class Paperback < ActiveRecord::Base; end
@@ -91,6 +114,15 @@ class ViewWithoutPrimaryKeyTest < ActiveRecord::TestCase
     assert_equal ["Agile Web Development with Rails"], books.map(&:name)
   end
 
+  def test_views
+    assert_equal [Paperback.table_name], @connection.views
+  end
+
+  def test_view_exists
+    view_name = Paperback.table_name
+    assert @connection.view_exists?(view_name), "'#{view_name}' view should exist"
+  end
+
   def test_table_exists
     view_name = Paperback.table_name
     assert @connection.table_exists?(view_name), "'#{view_name}' table should exist"
@@ -102,12 +134,83 @@ class ViewWithoutPrimaryKeyTest < ActiveRecord::TestCase
   end
 
   def test_attributes
-    assert_equal({"name" => "Agile Web Development with Rails", "status" => 0},
+    assert_equal({"name" => "Agile Web Development with Rails", "status" => 2},
                  Paperback.first.attributes)
   end
 
   def test_does_not_have_a_primary_key
     assert_nil Paperback.primary_key
   end
+
+  def test_does_not_dump_view_as_table
+    schema = dump_table_schema "paperbacks"
+    assert_no_match %r{create_table "paperbacks"}, schema
+  end
+end
+
+# sqlite dose not support CREATE, INSERT, and DELETE for VIEW
+if current_adapter?(:MysqlAdapter, :Mysql2Adapter, :PostgreSQLAdapter)
+class UpdateableViewTest < ActiveRecord::TestCase
+  self.use_transactional_tests = false
+  fixtures :books
+
+  class PrintedBook < ActiveRecord::Base
+    self.primary_key = "id"
+  end
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.execute <<-SQL
+      CREATE VIEW printed_books
+        AS SELECT id, name, status, format FROM books WHERE format = 'paperback'
+    SQL
+  end
+
+  teardown do
+    @connection.execute "DROP VIEW printed_books" if @connection.table_exists? "printed_books"
+  end
+
+  def test_update_record
+    book = PrintedBook.first
+    book.name = "AWDwR"
+    book.save!
+    book.reload
+    assert_equal "AWDwR", book.name
+  end
+
+  def test_insert_record
+    PrintedBook.create! name: "Rails in Action", status: 0, format: "paperback"
+
+    new_book = PrintedBook.last
+    assert_equal "Rails in Action", new_book.name
+  end
+
+  def test_update_record_to_fail_view_conditions
+    book = PrintedBook.first
+    book.format = "ebook"
+    book.save!
+
+    assert_raises ActiveRecord::RecordNotFound do
+      book.reload
+    end
+  end
+end
+end # end fo `if current_adapter?(:MysqlAdapter, :Mysql2Adapter, :PostgreSQLAdapter)`
+end # end fo `if ActiveRecord::Base.connection.supports_views?`
+
+if ActiveRecord::Base.connection.respond_to?(:supports_materialized_views?) &&
+    ActiveRecord::Base.connection.supports_materialized_views?
+class MaterializedViewTest < ActiveRecord::PostgreSQLTestCase
+  include ViewBehavior
+
+  private
+  def create_view(name, query)
+    @connection.execute "CREATE MATERIALIZED VIEW #{name} AS #{query}"
+  end
+
+  def drop_view(name)
+    @connection.execute "DROP MATERIALIZED VIEW #{name}" if @connection.table_exists? name
+
+  end
 end
 end
diff --git a/activerecord/test/cases/xml_serialization_test.rb b/activerecord/test/cases/xml_serialization_test.rb
deleted file mode 100644
index c34e7d5a30..0000000000
--- a/activerecord/test/cases/xml_serialization_test.rb
+++ /dev/null
@@ -1,447 +0,0 @@
-require "cases/helper"
-require "rexml/document"
-require 'models/contact'
-require 'models/post'
-require 'models/author'
-require 'models/comment'
-require 'models/company_in_module'
-require 'models/toy'
-require 'models/topic'
-require 'models/reply'
-require 'models/company'
-
-class XmlSerializationTest < ActiveRecord::TestCase
-  def test_should_serialize_default_root
-    @xml = Contact.new.to_xml
-    assert_match %r{^<contact>},  @xml
-    assert_match %r{</contact>$}, @xml
-  end
-
-  def test_should_serialize_default_root_with_namespace
-    @xml = Contact.new.to_xml :namespace=>"http://xml.rubyonrails.org/contact"
-    assert_match %r{^<contact xmlns="http://xml.rubyonrails.org/contact">},  @xml
-    assert_match %r{</contact>$}, @xml
-  end
-
-  def test_should_serialize_custom_root
-    @xml = Contact.new.to_xml :root => 'xml_contact'
-    assert_match %r{^<xml-contact>},  @xml
-    assert_match %r{</xml-contact>$}, @xml
-  end
-
-  def test_should_allow_undasherized_tags
-    @xml = Contact.new.to_xml :root => 'xml_contact', :dasherize => false
-    assert_match %r{^<xml_contact>},  @xml
-    assert_match %r{</xml_contact>$}, @xml
-    assert_match %r{<created_at},     @xml
-  end
-
-  def test_should_allow_camelized_tags
-    @xml = Contact.new.to_xml :root => 'xml_contact', :camelize => true
-    assert_match %r{^<XmlContact>},  @xml
-    assert_match %r{</XmlContact>$}, @xml
-    assert_match %r{<CreatedAt},    @xml
-  end
-
-  def test_should_allow_skipped_types
-    @xml = Contact.new(:age => 25).to_xml :skip_types => true
-    assert %r{<age>25</age>}.match(@xml)
-  end
-
-  def test_should_include_yielded_additions
-    @xml = Contact.new.to_xml do |xml|
-      xml.creator "David"
-    end
-    assert_match %r{<creator>David</creator>}, @xml
-  end
-
-  def test_to_xml_with_block
-    value = "Rockin' the block"
-    xml = Contact.new.to_xml(:skip_instruct => true) do |_xml|
-      _xml.tag! "arbitrary-element", value
-    end
-    assert_equal "<contact>", xml.first(9)
-    assert xml.include?(%(<arbitrary-element>#{value}</arbitrary-element>))
-  end
-
-  def test_should_skip_instruct_for_included_records
-    @contact = Contact.new
-    @contact.alternative = Contact.new(:name => 'Copa Cabana')
-    @xml = @contact.to_xml(:include => [ :alternative ])
-    assert_equal @xml.index('<?xml '), 0
-    assert_nil @xml.index('<?xml ', 1)
-  end
-end
-
-class DefaultXmlSerializationTest < ActiveRecord::TestCase
-  def setup
-    @contact = Contact.new(
-      :name        => 'aaron stack',
-      :age         => 25,
-      :avatar      => 'binarydata',
-      :created_at  => Time.utc(2006, 8, 1),
-      :awesome     => false,
-      :preferences => { :gem => 'ruby' }
-    )
-  end
-
-  def test_should_serialize_string
-    assert_match %r{<name>aaron stack</name>}, @contact.to_xml
-  end
-
-  def test_should_serialize_integer
-    assert_match %r{<age type="integer">25</age>}, @contact.to_xml
-  end
-
-  def test_should_serialize_binary
-    xml = @contact.to_xml
-    assert_match %r{YmluYXJ5ZGF0YQ==\n</avatar>},    xml
-    assert_match %r{<avatar(.*)(type="binary")},     xml
-    assert_match %r{<avatar(.*)(encoding="base64")}, xml
-  end
-
-  def test_should_serialize_datetime
-    assert_match %r{<created-at type=\"dateTime\">2006-08-01T00:00:00Z</created-at>}, @contact.to_xml
-  end
-
-  def test_should_serialize_boolean
-    assert_match %r{<awesome type=\"boolean\">false</awesome>}, @contact.to_xml
-  end
-
-  def test_should_serialize_hash
-    assert_match %r{<preferences>\s*<gem>ruby</gem>\s*</preferences>}m, @contact.to_xml
-  end
-
-  def test_uses_serializable_hash_with_only_option
-    def @contact.serializable_hash(options=nil)
-      super(only: %w(name))
-    end
-
-    xml = @contact.to_xml
-    assert_match %r{<name>aaron stack</name>}, xml
-    assert_no_match %r{age}, xml
-    assert_no_match %r{awesome}, xml
-  end
-
-  def test_uses_serializable_hash_with_except_option
-    def @contact.serializable_hash(options=nil)
-      super(except: %w(age))
-    end
-
-    xml = @contact.to_xml
-    assert_match %r{<name>aaron stack</name>}, xml
-    assert_match %r{<awesome type=\"boolean\">false</awesome>}, xml
-    assert_no_match %r{age}, xml
-  end
-
-  def test_does_not_include_inheritance_column_from_sti
-    @contact = ContactSti.new(@contact.attributes)
-    assert_equal 'ContactSti', @contact.type
-
-    xml = @contact.to_xml
-    assert_match %r{<name>aaron stack</name>}, xml
-    assert_no_match %r{<type}, xml
-    assert_no_match %r{ContactSti}, xml
-  end
-
-  def test_serializable_hash_with_default_except_option_and_excluding_inheritance_column_from_sti
-    @contact = ContactSti.new(@contact.attributes)
-    assert_equal 'ContactSti', @contact.type
-
-    def @contact.serializable_hash(options={})
-      super({ except: %w(age) }.merge!(options))
-    end
-
-    xml = @contact.to_xml
-    assert_match %r{<name>aaron stack</name>}, xml
-    assert_no_match %r{age}, xml
-    assert_no_match %r{<type}, xml
-    assert_no_match %r{ContactSti}, xml
-  end
-end
-
-class DefaultXmlSerializationTimezoneTest < ActiveRecord::TestCase
-  def test_should_serialize_datetime_with_timezone
-    with_timezone_config zone: "Pacific Time (US & Canada)" do
-      toy = Toy.create(:name => 'Mickey', :updated_at => Time.utc(2006, 8, 1))
-      assert_match %r{<updated-at type=\"dateTime\">2006-07-31T17:00:00-07:00</updated-at>}, toy.to_xml
-    end
-  end
-
-  def test_should_serialize_datetime_with_timezone_reloaded
-    with_timezone_config zone: "Pacific Time (US & Canada)" do
-      toy = Toy.create(:name => 'Minnie', :updated_at => Time.utc(2006, 8, 1)).reload
-      assert_match %r{<updated-at type=\"dateTime\">2006-07-31T17:00:00-07:00</updated-at>}, toy.to_xml
-    end
-  end
-end
-
-class NilXmlSerializationTest < ActiveRecord::TestCase
-  def setup
-    @xml = Contact.new.to_xml(:root => 'xml_contact')
-  end
-
-  def test_should_serialize_string
-    assert_match %r{<name nil="true"/>}, @xml
-  end
-
-  def test_should_serialize_integer
-    assert %r{<age (.*)/>}.match(@xml)
-    attributes = $1
-    assert_match %r{nil="true"}, attributes
-    assert_match %r{type="integer"}, attributes
-  end
-
-  def test_should_serialize_binary
-    assert %r{<avatar (.*)/>}.match(@xml)
-    attributes = $1
-    assert_match %r{type="binary"}, attributes
-    assert_match %r{encoding="base64"}, attributes
-    assert_match %r{nil="true"}, attributes
-  end
-
-  def test_should_serialize_datetime
-    assert %r{<created-at (.*)/>}.match(@xml)
-    attributes = $1
-    assert_match %r{nil="true"}, attributes
-    assert_match %r{type="dateTime"}, attributes
-  end
-
-  def test_should_serialize_boolean
-    assert %r{<awesome (.*)/>}.match(@xml)
-    attributes = $1
-    assert_match %r{type="boolean"}, attributes
-    assert_match %r{nil="true"}, attributes
-  end
-
-  def test_should_serialize_yaml
-    assert_match %r{<preferences nil=\"true\"/>}, @xml
-  end
-end
-
-class DatabaseConnectedXmlSerializationTest < ActiveRecord::TestCase
-  fixtures :topics, :companies, :accounts, :authors, :posts, :projects
-
-  def test_to_xml
-    xml = REXML::Document.new(topics(:first).to_xml(:indent => 0))
-    bonus_time_in_current_timezone = topics(:first).bonus_time.xmlschema
-    written_on_in_current_timezone = topics(:first).written_on.xmlschema
-
-    assert_equal "topic", xml.root.name
-    assert_equal "The First Topic" , xml.elements["//title"].text
-    assert_equal "David" , xml.elements["//author-name"].text
-    assert_match "Have a nice day", xml.elements["//content"].text
-
-    assert_equal "1", xml.elements["//id"].text
-    assert_equal "integer" , xml.elements["//id"].attributes['type']
-
-    assert_equal "1", xml.elements["//replies-count"].text
-    assert_equal "integer" , xml.elements["//replies-count"].attributes['type']
-
-    assert_equal written_on_in_current_timezone, xml.elements["//written-on"].text
-    assert_equal "dateTime" , xml.elements["//written-on"].attributes['type']
-
-    assert_equal "david@loudthinking.com", xml.elements["//author-email-address"].text
-
-    assert_equal nil, xml.elements["//parent-id"].text
-    assert_equal "integer", xml.elements["//parent-id"].attributes['type']
-    assert_equal "true", xml.elements["//parent-id"].attributes['nil']
-
-    # Oracle enhanced adapter allows to define Date attributes in model class (see topic.rb)
-    assert_equal "2004-04-15", xml.elements["//last-read"].text
-    assert_equal "date" , xml.elements["//last-read"].attributes['type']
-
-    # Oracle and DB2 don't have true boolean or time-only fields
-    unless current_adapter?(:OracleAdapter, :DB2Adapter)
-      assert_equal "false", xml.elements["//approved"].text
-      assert_equal "boolean" , xml.elements["//approved"].attributes['type']
-
-      assert_equal bonus_time_in_current_timezone, xml.elements["//bonus-time"].text
-      assert_equal "dateTime" , xml.elements["//bonus-time"].attributes['type']
-    end
-  end
-
-  def test_except_option
-    xml = topics(:first).to_xml(:indent => 0, :skip_instruct => true, :except => [:title, :replies_count])
-    assert_equal "<topic>", xml.first(7)
-    assert !xml.include?(%(<title>The First Topic</title>))
-    assert xml.include?(%(<author-name>David</author-name>))
-
-    xml = topics(:first).to_xml(:indent => 0, :skip_instruct => true, :except => [:title, :author_name, :replies_count])
-    assert !xml.include?(%(<title>The First Topic</title>))
-    assert !xml.include?(%(<author-name>David</author-name>))
-  end
-
-  # to_xml used to mess with the hash the user provided which
-  # caused the builder to be reused.  This meant the document kept
-  # getting appended to.
-
-  def test_modules
-    projects = MyApplication::Business::Project.all
-    xml = projects.to_xml
-    root = projects.first.class.to_s.underscore.pluralize.tr('/','_').dasherize
-    assert_match "<#{root} type=\"array\">", xml
-    assert_match "</#{root}>", xml
-  end
-
-  def test_passing_hash_shouldnt_reuse_builder
-    options = {:include=>:posts}
-    david = authors(:david)
-    first_xml_size = david.to_xml(options).size
-    second_xml_size = david.to_xml(options).size
-    assert_equal first_xml_size, second_xml_size
-  end
-
-  def test_include_uses_association_name
-    xml = authors(:david).to_xml :include=>:hello_posts, :indent => 0
-    assert_match %r{<hello-posts type="array">}, xml
-    assert_match %r{<hello-post type="Post">}, xml
-    assert_match %r{<hello-post type="StiPost">}, xml
-  end
-
-  def test_included_associations_should_skip_types
-    xml = authors(:david).to_xml :include=>:hello_posts, :indent => 0, :skip_types => true
-    assert_match %r{<hello-posts>}, xml
-    assert_match %r{<hello-post>}, xml
-    assert_match %r{<hello-post>}, xml
-  end
-
-  def test_including_has_many_association
-    xml = topics(:first).to_xml(:indent => 0, :skip_instruct => true, :include => :replies, :except => :replies_count)
-    assert_equal "<topic>", xml.first(7)
-    assert xml.include?(%(<replies type="array"><reply>))
-    assert xml.include?(%(<title>The Second Topic of the day</title>))
-  end
-
-  def test_including_belongs_to_association
-    xml = companies(:first_client).to_xml(:indent => 0, :skip_instruct => true, :include => :firm)
-    assert !xml.include?("<firm>")
-
-    xml = companies(:second_client).to_xml(:indent => 0, :skip_instruct => true, :include => :firm)
-    assert xml.include?("<firm>")
-  end
-
-  def test_including_multiple_associations
-    xml = companies(:first_firm).to_xml(:indent => 0, :skip_instruct => true, :include => [ :clients, :account ])
-    assert_equal "<firm>", xml.first(6)
-    assert xml.include?(%(<account>))
-    assert xml.include?(%(<clients type="array"><client>))
-  end
-
-  def test_including_association_with_options
-    xml = companies(:first_firm).to_xml(
-      :indent  => 0, :skip_instruct => true,
-      :include => { :clients => { :only => :name } }
-    )
-
-    assert_equal "<firm>", xml.first(6)
-    assert xml.include?(%(<client><name>Summit</name></client>))
-    assert xml.include?(%(<clients type="array"><client>))
-  end
-
-  def test_methods_are_called_on_object
-    xml = authors(:david).to_xml :methods => :label, :indent => 0
-    assert_match %r{<label>.*</label>}, xml
-  end
-
-  def test_should_not_call_methods_on_associations_that_dont_respond
-    xml = authors(:david).to_xml :include=>:hello_posts, :methods => :label, :indent => 2
-    assert !authors(:david).hello_posts.first.respond_to?(:label)
-    assert_match %r{^  <label>.*</label>}, xml
-    assert_no_match %r{^      <label>}, xml
-  end
-
-  def test_procs_are_called_on_object
-    proc = Proc.new { |options| options[:builder].tag!('nationality', 'Danish') }
-    xml = authors(:david).to_xml(:procs => [ proc ])
-    assert_match %r{<nationality>Danish</nationality>}, xml
-  end
-
-  def test_dual_arity_procs_are_called_on_object
-    proc = Proc.new { |options, record| options[:builder].tag!('name-reverse', record.name.reverse) }
-    xml = authors(:david).to_xml(:procs => [ proc ])
-    assert_match %r{<name-reverse>divaD</name-reverse>}, xml
-  end
-
-  def test_top_level_procs_arent_applied_to_associations
-    author_proc = Proc.new { |options| options[:builder].tag!('nationality', 'Danish') }
-    xml = authors(:david).to_xml(:procs => [ author_proc ], :include => :posts, :indent => 2)
-
-    assert_match %r{^  <nationality>Danish</nationality>}, xml
-    assert_no_match %r{^ {6}<nationality>Danish</nationality>}, xml
-  end
-
-  def test_procs_on_included_associations_are_called
-    posts_proc = Proc.new { |options| options[:builder].tag!('copyright', 'DHH') }
-    xml = authors(:david).to_xml(
-      :indent => 2,
-      :include => {
-        :posts => { :procs => [ posts_proc ] }
-      }
-    )
-
-    assert_no_match %r{^  <copyright>DHH</copyright>}, xml
-    assert_match %r{^ {6}<copyright>DHH</copyright>}, xml
-  end
-
-  def test_should_include_empty_has_many_as_empty_array
-    authors(:david).posts.delete_all
-    xml = authors(:david).to_xml :include=>:posts, :indent => 2
-
-    assert_equal [], Hash.from_xml(xml)['author']['posts']
-    assert_match %r{^  <posts type="array"/>}, xml
-  end
-
-  def test_should_has_many_array_elements_should_include_type_when_different_from_guessed_value
-    xml = authors(:david).to_xml :include=>:posts_with_comments, :indent => 2
-
-    assert Hash.from_xml(xml)
-    assert_match %r{^  <posts-with-comments type="array">}, xml
-    assert_match %r{^    <posts-with-comment type="Post">}, xml
-    assert_match %r{^    <posts-with-comment type="StiPost">}, xml
-
-    types = Hash.from_xml(xml)['author']['posts_with_comments'].collect {|t| t['type'] }
-    assert types.include?('SpecialPost')
-    assert types.include?('Post')
-    assert types.include?('StiPost')
-  end
-
-  def test_should_produce_xml_for_methods_returning_array
-    xml = authors(:david).to_xml(:methods => :social)
-    array = Hash.from_xml(xml)['author']['social']
-    assert_equal 2, array.size
-    assert array.include? 'twitter'
-    assert array.include? 'github'
-  end
-
-  def test_should_support_aliased_attributes
-    xml = Author.select("name as firstname").to_xml
-    Author.all.each do |author|
-      assert xml.include?(%(<firstname>#{author.name}</firstname>)), xml
-    end
-  end
-
-  def test_array_to_xml_including_has_many_association
-    xml = [ topics(:first), topics(:second) ].to_xml(:indent => 0, :skip_instruct => true, :include => :replies)
-    assert xml.include?(%(<replies type="array"><reply>))
-  end
-
-  def test_array_to_xml_including_methods
-    xml = [ topics(:first), topics(:second) ].to_xml(:indent => 0, :skip_instruct => true, :methods => [ :topic_id ])
-    assert xml.include?(%(<topic-id type="integer">#{topics(:first).topic_id}</topic-id>)), xml
-    assert xml.include?(%(<topic-id type="integer">#{topics(:second).topic_id}</topic-id>)), xml
-  end
-
-  def test_array_to_xml_including_has_one_association
-    xml = [ companies(:first_firm), companies(:rails_core) ].to_xml(:indent => 0, :skip_instruct => true, :include => :account)
-    assert xml.include?(companies(:first_firm).account.to_xml(:indent => 0, :skip_instruct => true))
-    assert xml.include?(companies(:rails_core).account.to_xml(:indent => 0, :skip_instruct => true))
-  end
-
-  def test_array_to_xml_including_belongs_to_association
-    xml = [ companies(:first_client), companies(:second_client), companies(:another_client) ].to_xml(:indent => 0, :skip_instruct => true, :include => :firm)
-    assert xml.include?(companies(:first_client).to_xml(:indent => 0, :skip_instruct => true))
-    assert xml.include?(companies(:second_client).firm.to_xml(:indent => 0, :skip_instruct => true))
-    assert xml.include?(companies(:another_client).firm.to_xml(:indent => 0, :skip_instruct => true))
-  end
-end
diff --git a/activerecord/test/cases/yaml_serialization_test.rb b/activerecord/test/cases/yaml_serialization_test.rb
index bce59b4fcd..56909a8630 100644
--- a/activerecord/test/cases/yaml_serialization_test.rb
+++ b/activerecord/test/cases/yaml_serialization_test.rb
@@ -83,4 +83,39 @@ class YamlSerializationTest < ActiveRecord::TestCase
     assert_equal 5, author.posts_count
     assert_equal 5, dumped.posts_count
   end
+
+  def test_a_yaml_version_is_provided_for_future_backwards_compat
+    coder = {}
+    Topic.first.encode_with(coder)
+
+    assert coder['active_record_yaml_version']
+  end
+
+  def test_deserializing_rails_41_yaml
+    topic = YAML.load(yaml_fixture("rails_4_1"))
+
+    assert topic.new_record?
+    assert_equal nil, topic.id
+    assert_equal "The First Topic", topic.title
+    assert_equal({ omg: :lol }, topic.content)
+  end
+
+  def test_deserializing_rails_4_2_0_yaml
+    topic = YAML.load(yaml_fixture("rails_4_2_0"))
+
+    assert_not topic.new_record?
+    assert_equal 1, topic.id
+    assert_equal "The First Topic", topic.title
+    assert_equal("Have a nice day", topic.content)
+  end
+
+  private
+
+  def yaml_fixture(file_name)
+    path = File.expand_path(
+      "../../support/yaml_compatibility_fixtures/#{file_name}.yml",
+      __FILE__
+    )
+    File.read(path)
+  end
 end
diff --git a/activerecord/test/fixtures/bad_posts.yml b/activerecord/test/fixtures/bad_posts.yml
new file mode 100644
index 0000000000..addee8e3bf
--- /dev/null
+++ b/activerecord/test/fixtures/bad_posts.yml
@@ -0,0 +1,9 @@
+# Please do not use this fixture without `set_fixture_class` as Post
+
+_fixture:
+  model_class: BadPostModel
+
+bad_welcome:
+  author_id: 1
+  title: Welcome to the another weblog
+  body: It's really nice today
diff --git a/activerecord/test/fixtures/books.yml b/activerecord/test/fixtures/books.yml
index abe56752c6..a304fba399 100644
--- a/activerecord/test/fixtures/books.yml
+++ b/activerecord/test/fixtures/books.yml
@@ -3,9 +3,29 @@ awdr:
   id: 1
   name: "Agile Web Development with Rails"
   format: "paperback"
+  status: :published
+  read_status: :read
+  language: :english
+  author_visibility: :visible
+  illustrator_visibility: :visible
+  font_size: :medium
 
 rfr:
   author_id: 1
   id: 2
   name: "Ruby for Rails"
   format: "ebook"
+  status: "proposed"
+  read_status: "reading"
+
+ddd:
+  author_id: 1
+  id: 3
+  name: "Domain-Driven Design"
+  format: "hardcover"
+  status: 2
+
+tlg:
+  author_id: 1
+  id: 4
+  name: "Thoughtleadering"
diff --git a/activerecord/test/fixtures/dead_parrots.yml b/activerecord/test/fixtures/dead_parrots.yml
new file mode 100644
index 0000000000..da5529dd27
--- /dev/null
+++ b/activerecord/test/fixtures/dead_parrots.yml
@@ -0,0 +1,5 @@
+deadbird:
+  name: "Dusty DeadBird"
+  treasures: [ruby, sapphire]
+  parrot_sti_class: DeadParrot
+  killer: blackbeard
diff --git a/activerecord/test/fixtures/doubloons.yml b/activerecord/test/fixtures/doubloons.yml
new file mode 100644
index 0000000000..efd1643971
--- /dev/null
+++ b/activerecord/test/fixtures/doubloons.yml
@@ -0,0 +1,3 @@
+blackbeards_doubloon:
+  pirate: blackbeard
+  weight: 2
diff --git a/activerecord/test/fixtures/live_parrots.yml b/activerecord/test/fixtures/live_parrots.yml
new file mode 100644
index 0000000000..95b2078da7
--- /dev/null
+++ b/activerecord/test/fixtures/live_parrots.yml
@@ -0,0 +1,4 @@
+dusty:
+  name: "Dusty Bluebird"
+  treasures: [ruby, sapphire]
+  parrot_sti_class: LiveParrot
diff --git a/activerecord/test/fixtures/naked/yml/parrots.yml b/activerecord/test/fixtures/naked/yml/parrots.yml
new file mode 100644
index 0000000000..3e10331105
--- /dev/null
+++ b/activerecord/test/fixtures/naked/yml/parrots.yml
@@ -0,0 +1,2 @@
+george:
+  arrr: "Curious George"
diff --git a/activerecord/test/fixtures/nodes.yml b/activerecord/test/fixtures/nodes.yml
new file mode 100644
index 0000000000..b8bb8216ee
--- /dev/null
+++ b/activerecord/test/fixtures/nodes.yml
@@ -0,0 +1,29 @@
+grandparent:
+  id: 1
+  tree_id: 1
+  name: Grand Parent
+
+parent_a:
+  id: 2
+  tree_id: 1
+  parent_id: 1
+  name: Parent A
+
+parent_b:
+  id: 3
+  tree_id: 1
+  parent_id: 1
+  name: Parent B
+
+child_one_of_a:
+  id: 4
+  tree_id: 1
+  parent_id: 2
+  name: Child one
+
+child_two_of_b:
+  id: 5
+  tree_id: 1
+  parent_id: 2
+  name: Child two
+
diff --git a/activerecord/test/fixtures/other_comments.yml b/activerecord/test/fixtures/other_comments.yml
new file mode 100644
index 0000000000..55e8216ec7
--- /dev/null
+++ b/activerecord/test/fixtures/other_comments.yml
@@ -0,0 +1,6 @@
+_fixture:
+  model_class: Comment
+
+second_greetings:
+  post: second_welcome
+  body: Thank you for the second welcome
diff --git a/activerecord/test/fixtures/other_posts.yml b/activerecord/test/fixtures/other_posts.yml
new file mode 100644
index 0000000000..39ff763547
--- /dev/null
+++ b/activerecord/test/fixtures/other_posts.yml
@@ -0,0 +1,7 @@
+_fixture:
+  model_class: Post
+
+second_welcome:
+  author_id: 1
+  title: Welcome to the another weblog
+  body: It's really nice today
diff --git a/activerecord/test/fixtures/trees.yml b/activerecord/test/fixtures/trees.yml
new file mode 100644
index 0000000000..9e030b7632
--- /dev/null
+++ b/activerecord/test/fixtures/trees.yml
@@ -0,0 +1,3 @@
+root:
+  id: 1
+  name: The Root
diff --git a/activerecord/test/migrations/missing/1000_people_have_middle_names.rb b/activerecord/test/migrations/missing/1000_people_have_middle_names.rb
index 9fd495b97c..4b83d61beb 100644
--- a/activerecord/test/migrations/missing/1000_people_have_middle_names.rb
+++ b/activerecord/test/migrations/missing/1000_people_have_middle_names.rb
@@ -6,4 +6,4 @@ class PeopleHaveMiddleNames < ActiveRecord::Migration
   def self.down
     remove_column "people", "middle_name"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/missing/1_people_have_last_names.rb b/activerecord/test/migrations/missing/1_people_have_last_names.rb
index 81af5fef5e..68209f3ce9 100644
--- a/activerecord/test/migrations/missing/1_people_have_last_names.rb
+++ b/activerecord/test/migrations/missing/1_people_have_last_names.rb
@@ -6,4 +6,4 @@ class PeopleHaveLastNames < ActiveRecord::Migration
   def self.down
     remove_column "people", "last_name"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/missing/3_we_need_reminders.rb b/activerecord/test/migrations/missing/3_we_need_reminders.rb
index d5e71ce8ef..25bb49cb32 100644
--- a/activerecord/test/migrations/missing/3_we_need_reminders.rb
+++ b/activerecord/test/migrations/missing/3_we_need_reminders.rb
@@ -9,4 +9,4 @@ class WeNeedReminders < ActiveRecord::Migration
   def self.down
     drop_table "reminders"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/missing/4_innocent_jointable.rb b/activerecord/test/migrations/missing/4_innocent_jointable.rb
index 21c9ca5328..002a1bf2a6 100644
--- a/activerecord/test/migrations/missing/4_innocent_jointable.rb
+++ b/activerecord/test/migrations/missing/4_innocent_jointable.rb
@@ -9,4 +9,4 @@ class InnocentJointable < ActiveRecord::Migration
   def self.down
     drop_table "people_reminders"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/rename/1_we_need_things.rb b/activerecord/test/migrations/rename/1_we_need_things.rb
index cdbe0b1679..f5484ac54f 100644
--- a/activerecord/test/migrations/rename/1_we_need_things.rb
+++ b/activerecord/test/migrations/rename/1_we_need_things.rb
@@ -8,4 +8,4 @@ class WeNeedThings < ActiveRecord::Migration
   def self.down
     drop_table "things"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/rename/2_rename_things.rb b/activerecord/test/migrations/rename/2_rename_things.rb
index d441b71fc9..533a113ea8 100644
--- a/activerecord/test/migrations/rename/2_rename_things.rb
+++ b/activerecord/test/migrations/rename/2_rename_things.rb
@@ -6,4 +6,4 @@ class RenameThings < ActiveRecord::Migration
   def self.down
     rename_table "awesome_things", "things"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/valid/2_we_need_reminders.rb b/activerecord/test/migrations/valid/2_we_need_reminders.rb
index d5e71ce8ef..25bb49cb32 100644
--- a/activerecord/test/migrations/valid/2_we_need_reminders.rb
+++ b/activerecord/test/migrations/valid/2_we_need_reminders.rb
@@ -9,4 +9,4 @@ class WeNeedReminders < ActiveRecord::Migration
   def self.down
     drop_table "reminders"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/valid/3_innocent_jointable.rb b/activerecord/test/migrations/valid/3_innocent_jointable.rb
index 21c9ca5328..002a1bf2a6 100644
--- a/activerecord/test/migrations/valid/3_innocent_jointable.rb
+++ b/activerecord/test/migrations/valid/3_innocent_jointable.rb
@@ -9,4 +9,4 @@ class InnocentJointable < ActiveRecord::Migration
   def self.down
     drop_table "people_reminders"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/valid_with_subdirectories/sub/2_we_need_reminders.rb b/activerecord/test/migrations/valid_with_subdirectories/sub/2_we_need_reminders.rb
index d5e71ce8ef..25bb49cb32 100644
--- a/activerecord/test/migrations/valid_with_subdirectories/sub/2_we_need_reminders.rb
+++ b/activerecord/test/migrations/valid_with_subdirectories/sub/2_we_need_reminders.rb
@@ -9,4 +9,4 @@ class WeNeedReminders < ActiveRecord::Migration
   def self.down
     drop_table "reminders"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/migrations/valid_with_subdirectories/sub1/3_innocent_jointable.rb b/activerecord/test/migrations/valid_with_subdirectories/sub1/3_innocent_jointable.rb
index 21c9ca5328..002a1bf2a6 100644
--- a/activerecord/test/migrations/valid_with_subdirectories/sub1/3_innocent_jointable.rb
+++ b/activerecord/test/migrations/valid_with_subdirectories/sub1/3_innocent_jointable.rb
@@ -9,4 +9,4 @@ class InnocentJointable < ActiveRecord::Migration
   def self.down
     drop_table "people_reminders"
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/models/admin.rb b/activerecord/test/models/admin.rb
index 00e69fbed8..a38e3f4846 100644
--- a/activerecord/test/models/admin.rb
+++ b/activerecord/test/models/admin.rb
@@ -2,4 +2,4 @@ module Admin
   def self.table_name_prefix
     'admin_'
   end
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/models/admin/account.rb b/activerecord/test/models/admin/account.rb
index 46de28aae1..bd23192d20 100644
--- a/activerecord/test/models/admin/account.rb
+++ b/activerecord/test/models/admin/account.rb
@@ -1,3 +1,3 @@
 class Admin::Account < ActiveRecord::Base
   has_many :users
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/models/admin/randomly_named_c1.rb b/activerecord/test/models/admin/randomly_named_c1.rb
index 2f81d5b831..b64ae7fc41 100644
--- a/activerecord/test/models/admin/randomly_named_c1.rb
+++ b/activerecord/test/models/admin/randomly_named_c1.rb
@@ -1,3 +1,7 @@
-class Admin::ClassNameThatDoesNotFollowCONVENTIONS < ActiveRecord::Base

-  self.table_name = :randomly_named_table

+class Admin::ClassNameThatDoesNotFollowCONVENTIONS1 < ActiveRecord::Base

+  self.table_name = :randomly_named_table2

+end

+

+class Admin::ClassNameThatDoesNotFollowCONVENTIONS2 < ActiveRecord::Base

+  self.table_name = :randomly_named_table3

 end

diff --git a/activerecord/test/models/aircraft.rb b/activerecord/test/models/aircraft.rb
index 1f35ef45da..c4404a8094 100644
--- a/activerecord/test/models/aircraft.rb
+++ b/activerecord/test/models/aircraft.rb
@@ -1,4 +1,5 @@
 class Aircraft < ActiveRecord::Base
   self.pluralize_table_names = false
   has_many :engines, :foreign_key => "car_id"
+  has_many :wheels, as: :wheelable
 end
diff --git a/activerecord/test/models/author.rb b/activerecord/test/models/author.rb
index 8c1f14bd36..0d90cbb110 100644
--- a/activerecord/test/models/author.rb
+++ b/activerecord/test/models/author.rb
@@ -144,9 +144,6 @@ class Author < ActiveRecord::Base
 
   has_many :posts_with_signature, ->(record) { where("posts.title LIKE ?", "%by #{record.name.downcase}%") }, class_name: "Post"
 
-  scope :relation_include_posts, -> { includes(:posts) }
-  scope :relation_include_tags,  -> { includes(:tags) }
-
   attr_accessor :post_log
   after_initialize :set_post_log
 
diff --git a/activerecord/test/models/binary.rb b/activerecord/test/models/binary.rb
index 950c459199..39b2f5090a 100644
--- a/activerecord/test/models/binary.rb
+++ b/activerecord/test/models/binary.rb
@@ -1,2 +1,2 @@
 class Binary < ActiveRecord::Base
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/models/book.rb b/activerecord/test/models/book.rb
index 2170018068..1927191393 100644
--- a/activerecord/test/models/book.rb
+++ b/activerecord/test/models/book.rb
@@ -10,6 +10,10 @@ class Book < ActiveRecord::Base
   enum status: [:proposed, :written, :published]
   enum read_status: {unread: 0, reading: 2, read: 3}
   enum nullable_status: [:single, :married]
+  enum language: [:english, :spanish, :french], _prefix: :in
+  enum author_visibility: [:visible, :invisible], _prefix: true
+  enum illustrator_visibility: [:visible, :invisible], _prefix: true
+  enum font_size: [:small, :medium, :large], _prefix: :with, _suffix: true
 
   def published!
     super
diff --git a/activerecord/test/models/car.rb b/activerecord/test/models/car.rb
index db0f93f63b..81263b79d1 100644
--- a/activerecord/test/models/car.rb
+++ b/activerecord/test/models/car.rb
@@ -8,7 +8,7 @@ class Car < ActiveRecord::Base
   has_one :bulb
 
   has_many :tyres
-  has_many :engines, :dependent => :destroy
+  has_many :engines, :dependent => :destroy, inverse_of: :my_car
   has_many :wheels, :as => :wheelable, :dependent => :destroy
 
   scope :incl_tyres, -> { includes(:tyres) }
diff --git a/activerecord/test/models/carrier.rb b/activerecord/test/models/carrier.rb
new file mode 100644
index 0000000000..230be118c3
--- /dev/null
+++ b/activerecord/test/models/carrier.rb
@@ -0,0 +1,2 @@
+class Carrier < ActiveRecord::Base
+end
diff --git a/activerecord/test/models/categorization.rb b/activerecord/test/models/categorization.rb
index 6588531de6..4cd67c970a 100644
--- a/activerecord/test/models/categorization.rb
+++ b/activerecord/test/models/categorization.rb
@@ -1,6 +1,6 @@
 class Categorization < ActiveRecord::Base
   belongs_to :post
-  belongs_to :category
+  belongs_to :category, counter_cache: true
   belongs_to :named_category, :class_name => 'Category', :foreign_key => :named_category_name, :primary_key => :name
   belongs_to :author
 
diff --git a/activerecord/test/models/chef.rb b/activerecord/test/models/chef.rb
index 67a4e54f06..698a52e045 100644
--- a/activerecord/test/models/chef.rb
+++ b/activerecord/test/models/chef.rb
@@ -1,3 +1,4 @@
 class Chef < ActiveRecord::Base
   belongs_to :employable, polymorphic: true
+  has_many :recipes
 end
diff --git a/activerecord/test/models/company.rb b/activerecord/test/models/company.rb
index 5a56616eb9..1dcd9fc21e 100644
--- a/activerecord/test/models/company.rb
+++ b/activerecord/test/models/company.rb
@@ -10,7 +10,6 @@ class Company < AbstractCompany
   has_one :dummy_account, :foreign_key => "firm_id", :class_name => "Account"
   has_many :contracts
   has_many :developers, :through => :contracts
-  has_many :accounts
 
   scope :of_first_firm, lambda {
     joins(:account => :firm).
@@ -26,6 +25,9 @@ class Company < AbstractCompany
   def private_method
     "I am Jack's innermost fears and aspirations"
   end
+
+  class SpecialCo < Company
+  end
 end
 
 module Namespaced
@@ -83,6 +85,9 @@ class Firm < Company
 
   has_many :association_with_references, -> { references(:foo) }, :class_name => 'Client'
 
+  has_one :lead_developer, class_name: "Developer"
+  has_many :projects
+
   def log
     @log ||= []
   end
@@ -214,7 +219,7 @@ class Account < ActiveRecord::Base
   protected
 
   def check_empty_credit_limit
-    errors.add_on_empty "credit_limit"
+    errors.add("credit_limit", :blank) if credit_limit.blank?
   end
 
   private
diff --git a/activerecord/test/models/company_in_module.rb b/activerecord/test/models/company_in_module.rb
index dae102d12b..bf0a0d1c3e 100644
--- a/activerecord/test/models/company_in_module.rb
+++ b/activerecord/test/models/company_in_module.rb
@@ -91,7 +91,7 @@ module MyApplication
       protected
 
       def check_empty_credit_limit
-        errors.add_on_empty "credit_limit"
+        errors.add("credit_card", :blank) if credit_card.blank?
       end
     end
   end
diff --git a/activerecord/test/models/contact.rb b/activerecord/test/models/contact.rb
index 3ea17c3abf..9f2f69e1ee 100644
--- a/activerecord/test/models/contact.rb
+++ b/activerecord/test/models/contact.rb
@@ -3,7 +3,7 @@ module ContactFakeColumns
     base.class_eval do
       establish_connection(:adapter => 'fake')
 
-      connection.tables = [table_name]
+      connection.data_sources = [table_name]
       connection.primary_keys = {
         table_name => 'id'
       }
diff --git a/activerecord/test/models/customer_carrier.rb b/activerecord/test/models/customer_carrier.rb
new file mode 100644
index 0000000000..37186903ff
--- /dev/null
+++ b/activerecord/test/models/customer_carrier.rb
@@ -0,0 +1,14 @@
+class CustomerCarrier < ActiveRecord::Base
+  cattr_accessor :current_customer
+
+  belongs_to :customer
+  belongs_to :carrier
+
+  default_scope -> {
+    if current_customer
+      where(customer: current_customer)
+    else
+      all
+    end
+  }
+end
diff --git a/activerecord/test/models/developer.rb b/activerecord/test/models/developer.rb
index d2a5a7fc49..9a907273f8 100644
--- a/activerecord/test/models/developer.rb
+++ b/activerecord/test/models/developer.rb
@@ -7,12 +7,16 @@ module DeveloperProjectsAssociationExtension2
 end
 
 class Developer < ActiveRecord::Base
+  self.ignored_columns = %w(first_name last_name)
+
   has_and_belongs_to_many :projects do
     def find_most_recent
       order("id DESC").first
     end
   end
 
+  belongs_to :mentor
+
   accepts_nested_attributes_for :projects
 
   has_and_belongs_to_many :shared_computers, class_name: "Computer"
@@ -50,6 +54,10 @@ class Developer < ActiveRecord::Base
   has_many :firms, :through => :contracts, :source => :firm
   has_many :comments, ->(developer) { where(body: "I'm #{developer.name}") }
   has_many :ratings, through: :comments
+  has_one :ship, dependent: :nullify
+
+  belongs_to :firm
+  has_many :contracted_projects, class_name: "Project"
 
   scope :jamises, -> { where(:name => 'Jamis') }
 
@@ -60,6 +68,9 @@ class Developer < ActiveRecord::Base
     developer.audit_logs.build :message => "Computer created"
   end
 
+  attr_accessor :last_name
+  define_attribute_method 'last_name'
+
   def log=(message)
     audit_logs.build :message => message
   end
diff --git a/activerecord/test/models/doubloon.rb b/activerecord/test/models/doubloon.rb
new file mode 100644
index 0000000000..2b11d128e2
--- /dev/null
+++ b/activerecord/test/models/doubloon.rb
@@ -0,0 +1,12 @@
+class AbstractDoubloon < ActiveRecord::Base
+  # This has functionality that might be shared by multiple classes.
+
+  self.abstract_class = true
+  belongs_to :pirate
+end
+
+class Doubloon < AbstractDoubloon
+  # This uses an abstract class that defines attributes and associations.
+
+  self.table_name = 'doubloons'
+end
diff --git a/activerecord/test/models/event.rb b/activerecord/test/models/event.rb
index 99fa0feeb7..365ab32b0b 100644
--- a/activerecord/test/models/event.rb
+++ b/activerecord/test/models/event.rb
@@ -1,3 +1,3 @@
 class Event < ActiveRecord::Base
   validates_uniqueness_of :title
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/models/face.rb b/activerecord/test/models/face.rb
index 91e46f83e5..af76fea52c 100644
--- a/activerecord/test/models/face.rb
+++ b/activerecord/test/models/face.rb
@@ -1,7 +1,7 @@
 class Face < ActiveRecord::Base
   belongs_to :man, :inverse_of => :face
   belongs_to :polymorphic_man, :polymorphic => true, :inverse_of => :polymorphic_face
-  # Oracle identifier lengh is limited to 30 bytes or less, `polymorphic` renamed `poly`
+  # Oracle identifier length is limited to 30 bytes or less, `polymorphic` renamed `poly`
   belongs_to :poly_man_without_inverse, :polymorphic => true
   # These is a "broken" inverse_of for the purposes of testing
   belongs_to :horrible_man, :class_name => 'Man', :inverse_of => :horrible_face
diff --git a/activerecord/test/models/guid.rb b/activerecord/test/models/guid.rb
index 9208dc28fa..05653ba498 100644
--- a/activerecord/test/models/guid.rb
+++ b/activerecord/test/models/guid.rb
@@ -1,2 +1,2 @@
 class Guid < ActiveRecord::Base
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/models/guitar.rb b/activerecord/test/models/guitar.rb
new file mode 100644
index 0000000000..cd068ff53d
--- /dev/null
+++ b/activerecord/test/models/guitar.rb
@@ -0,0 +1,4 @@
+class Guitar < ActiveRecord::Base
+  has_many :tuning_pegs, index_errors: true
+  accepts_nested_attributes_for :tuning_pegs
+end
diff --git a/activerecord/test/models/hotel.rb b/activerecord/test/models/hotel.rb
index b352cd22f3..491f8dfde3 100644
--- a/activerecord/test/models/hotel.rb
+++ b/activerecord/test/models/hotel.rb
@@ -3,4 +3,5 @@ class Hotel < ActiveRecord::Base
   has_many :chefs, through: :departments
   has_many :cake_designers, source_type: 'CakeDesigner', source: :employable, through: :chefs
   has_many :drink_designers, source_type: 'DrinkDesigner', source: :employable, through: :chefs
+  has_many :recipes, through: :chefs
 end
diff --git a/activerecord/test/models/member.rb b/activerecord/test/models/member.rb
index dc0566d8a7..7693c6e515 100644
--- a/activerecord/test/models/member.rb
+++ b/activerecord/test/models/member.rb
@@ -26,6 +26,9 @@ class Member < ActiveRecord::Base
   has_many :current_memberships, -> { where :favourite => true }
   has_many :clubs, :through => :current_memberships
 
+  has_many :tenant_memberships
+  has_many :tenant_clubs, through: :tenant_memberships, class_name: 'Club', source: :club
+
   has_one :club_through_many, :through => :current_memberships, :source => :club
 
   belongs_to :admittable, polymorphic: true
diff --git a/activerecord/test/models/member_detail.rb b/activerecord/test/models/member_detail.rb
index 9d253aa126..157130986c 100644
--- a/activerecord/test/models/member_detail.rb
+++ b/activerecord/test/models/member_detail.rb
@@ -1,7 +1,8 @@
 class MemberDetail < ActiveRecord::Base
-  belongs_to :member, :inverse_of => false
+  belongs_to :member, inverse_of: false
   belongs_to :organization
-  has_one :member_type, :through => :member
+  has_one :member_type, through: :member
+  has_one :membership, through: :member
 
-  has_many :organization_member_details, :through => :organization, :source => :member_details
+  has_many :organization_member_details, through: :organization, source: :member_details
 end
diff --git a/activerecord/test/models/membership.rb b/activerecord/test/models/membership.rb
index df7167ee93..e181ba1f11 100644
--- a/activerecord/test/models/membership.rb
+++ b/activerecord/test/models/membership.rb
@@ -18,3 +18,18 @@ class SelectedMembership < Membership
     select("'1' as foo")
   end
 end
+
+class TenantMembership < Membership
+  cattr_accessor :current_member
+
+  belongs_to :member
+  belongs_to :club
+
+  default_scope -> {
+    if current_member
+      where(member: current_member)
+    else
+      all
+    end
+  }
+end
diff --git a/activerecord/test/models/mentor.rb b/activerecord/test/models/mentor.rb
new file mode 100644
index 0000000000..11f1e4bff8
--- /dev/null
+++ b/activerecord/test/models/mentor.rb
@@ -0,0 +1,3 @@
+class Mentor < ActiveRecord::Base
+  has_many :developers
+end
\ No newline at end of file
diff --git a/activerecord/test/models/node.rb b/activerecord/test/models/node.rb
new file mode 100644
index 0000000000..07dd2dbccb
--- /dev/null
+++ b/activerecord/test/models/node.rb
@@ -0,0 +1,5 @@
+class Node < ActiveRecord::Base
+  belongs_to :tree, touch: true
+  belongs_to :parent,   class_name: 'Node', touch: true, optional: true
+  has_many   :children, class_name: 'Node', foreign_key: :parent_id, dependent: :destroy
+end
diff --git a/activerecord/test/models/notification.rb b/activerecord/test/models/notification.rb
new file mode 100644
index 0000000000..b4b4b8f1b6
--- /dev/null
+++ b/activerecord/test/models/notification.rb
@@ -0,0 +1,2 @@
+class Notification < ActiveRecord::Base
+end
diff --git a/activerecord/test/models/parrot.rb b/activerecord/test/models/parrot.rb
index b26035d944..ddc9dcaf29 100644
--- a/activerecord/test/models/parrot.rb
+++ b/activerecord/test/models/parrot.rb
@@ -21,9 +21,3 @@ end
 class DeadParrot < Parrot
   belongs_to :killer, :class_name => 'Pirate', foreign_key: :killer_id
 end
-
-class FunkyParrot < Parrot
-  before_destroy do
-    raise "before_destroy was called"
-  end
-end
diff --git a/activerecord/test/models/person.rb b/activerecord/test/models/person.rb
index ad12f00d42..a4a9c6b0d4 100644
--- a/activerecord/test/models/person.rb
+++ b/activerecord/test/models/person.rb
@@ -37,7 +37,6 @@ class Person < ActiveRecord::Base
   has_many :essays, primary_key: "first_name", foreign_key: "writer_id"
 
   scope :males,   -> { where(:gender => 'M') }
-  scope :females, -> { where(:gender => 'F') }
 end
 
 class PersonWithDependentDestroyJobs < ActiveRecord::Base
diff --git a/activerecord/test/models/pirate.rb b/activerecord/test/models/pirate.rb
index 366c70f902..30545bdcd7 100644
--- a/activerecord/test/models/pirate.rb
+++ b/activerecord/test/models/pirate.rb
@@ -89,4 +89,4 @@ class FamousPirate < ActiveRecord::Base
   self.table_name = 'pirates'
   has_many :famous_ships
   validates_presence_of :catchphrase, on: :conference
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/models/post.rb b/activerecord/test/models/post.rb
index 7b637c9e3f..81a18188d4 100644
--- a/activerecord/test/models/post.rb
+++ b/activerecord/test/models/post.rb
@@ -18,6 +18,7 @@ class Post < ActiveRecord::Base
   end
 
   scope :containing_the_letter_a, -> { where("body LIKE '%a%'") }
+  scope :titled_with_an_apostrophe, -> { where("title LIKE '%''%'") }
   scope :ranked_by_comments,      -> { order("comments_count DESC") }
 
   scope :limit_by, lambda {|l| limit(l) }
@@ -43,6 +44,8 @@ class Post < ActiveRecord::Base
   scope :tagged_with, ->(id) { joins(:taggings).where(taggings: { tag_id: id }) }
   scope :tagged_with_comment, ->(comment) { joins(:taggings).where(taggings: { comment: comment }) }
 
+  scope :typographically_interesting, -> { containing_the_letter_a.or(titled_with_an_apostrophe) }
+
   has_many   :comments do
     def find_most_recent
       order("id DESC").first
@@ -95,11 +98,11 @@ class Post < ActiveRecord::Base
     end
   end
 
-  has_many :taggings_with_delete_all, :class_name => 'Tagging', :as => :taggable, :dependent => :delete_all
-  has_many :taggings_with_destroy, :class_name => 'Tagging', :as => :taggable, :dependent => :destroy
+  has_many :taggings_with_delete_all, :class_name => 'Tagging', :as => :taggable, :dependent => :delete_all, counter_cache: :taggings_with_delete_all_count
+  has_many :taggings_with_destroy, :class_name => 'Tagging', :as => :taggable, :dependent => :destroy, counter_cache: :taggings_with_destroy_count
 
-  has_many :tags_with_destroy, :through => :taggings, :source => :tag, :dependent => :destroy
-  has_many :tags_with_nullify, :through => :taggings, :source => :tag, :dependent => :nullify
+  has_many :tags_with_destroy, :through => :taggings, :source => :tag, :dependent => :destroy, counter_cache: :tags_with_destroy_count
+  has_many :tags_with_nullify, :through => :taggings, :source => :tag, :dependent => :nullify, counter_cache: :tags_with_nullify_count
 
   has_many :misc_tags, -> { where :tags => { :name => 'Misc' } }, :through => :taggings, :source => :tag
   has_many :funky_tags, :through => :taggings, :source => :tag
@@ -205,6 +208,22 @@ class PostWithDefaultScope < ActiveRecord::Base
   default_scope { order(:title) }
 end
 
+class PostWithPreloadDefaultScope < ActiveRecord::Base
+  self.table_name = 'posts'
+
+  has_many :readers, foreign_key: 'post_id'
+
+  default_scope { preload(:readers) }
+end
+
+class PostWithIncludesDefaultScope < ActiveRecord::Base
+  self.table_name = 'posts'
+
+  has_many :readers, foreign_key: 'post_id'
+
+  default_scope { includes(:readers) }
+end
+
 class SpecialPostWithDefaultScope < ActiveRecord::Base
   self.table_name = 'posts'
   default_scope { where(:id => [1, 5,6]) }
diff --git a/activerecord/test/models/professor.rb b/activerecord/test/models/professor.rb
new file mode 100644
index 0000000000..7654eda0ef
--- /dev/null
+++ b/activerecord/test/models/professor.rb
@@ -0,0 +1,5 @@
+require_dependency 'models/arunit2_model'
+
+class Professor < ARUnit2Model
+  has_and_belongs_to_many :courses
+end
diff --git a/activerecord/test/models/project.rb b/activerecord/test/models/project.rb
index 7f42a4b1f8..b034e0e267 100644
--- a/activerecord/test/models/project.rb
+++ b/activerecord/test/models/project.rb
@@ -1,4 +1,5 @@
 class Project < ActiveRecord::Base
+  belongs_to :mentor
   has_and_belongs_to_many :developers, -> { distinct.order 'developers.name desc, developers.id desc' }
   has_and_belongs_to_many :readonly_developers, -> { readonly }, :class_name => "Developer"
   has_and_belongs_to_many :non_unique_developers, -> { order 'developers.name desc, developers.id desc' }, :class_name => 'Developer'
@@ -11,6 +12,8 @@ class Project < ActiveRecord::Base
                             :before_remove => Proc.new {|o, r| o.developers_log << "before_removing#{r.id}"},
                             :after_remove => Proc.new {|o, r| o.developers_log << "after_removing#{r.id}"}
   has_and_belongs_to_many :well_payed_salary_groups, -> { group("developers.salary").having("SUM(salary) > 10000").select("SUM(salary) as salary") }, :class_name => "Developer"
+  belongs_to :firm
+  has_one :lead_developer, through: :firm, inverse_of: :contracted_projects
 
   attr_accessor :developers_log
   after_initialize :set_developers_log
diff --git a/activerecord/test/models/randomly_named_c1.rb b/activerecord/test/models/randomly_named_c1.rb
index 18a86c4989..d4be1e13b4 100644
--- a/activerecord/test/models/randomly_named_c1.rb
+++ b/activerecord/test/models/randomly_named_c1.rb
@@ -1,3 +1,3 @@
 class ClassNameThatDoesNotFollowCONVENTIONS < ActiveRecord::Base

-  self.table_name = :randomly_named_table

+  self.table_name = :randomly_named_table1

 end

diff --git a/activerecord/test/models/recipe.rb b/activerecord/test/models/recipe.rb
new file mode 100644
index 0000000000..c387230603
--- /dev/null
+++ b/activerecord/test/models/recipe.rb
@@ -0,0 +1,3 @@
+class Recipe < ActiveRecord::Base
+  belongs_to :chef
+end
diff --git a/activerecord/test/models/ship.rb b/activerecord/test/models/ship.rb
index c2f6d492d8..e333b964ab 100644
--- a/activerecord/test/models/ship.rb
+++ b/activerecord/test/models/ship.rb
@@ -3,7 +3,9 @@ class Ship < ActiveRecord::Base
 
   belongs_to :pirate
   belongs_to :update_only_pirate, :class_name => 'Pirate'
+  belongs_to :developer, dependent: :destroy
   has_many :parts, :class_name => 'ShipPart'
+  has_many :treasures
 
   accepts_nested_attributes_for :parts, :allow_destroy => true
   accepts_nested_attributes_for :pirate, :allow_destroy => true, :reject_if => proc(&:empty?)
@@ -18,6 +20,18 @@ class Ship < ActiveRecord::Base
   end
 end
 
+class ShipWithoutNestedAttributes < ActiveRecord::Base
+  self.table_name = "ships"
+  has_many :prisoners, inverse_of: :ship, foreign_key: :ship_id
+  has_many :parts, class_name: "ShipPart", foreign_key: :ship_id
+
+  validates :name, presence: true
+end
+
+class Prisoner < ActiveRecord::Base
+  belongs_to :ship, autosave: true, class_name: "ShipWithoutNestedAttributes", inverse_of: :prisoners
+end
+
 class FamousShip < ActiveRecord::Base
   self.table_name = 'ships'
   belongs_to :famous_pirate
diff --git a/activerecord/test/models/ship_part.rb b/activerecord/test/models/ship_part.rb
index b6a8a506b4..05c65f8a4a 100644
--- a/activerecord/test/models/ship_part.rb
+++ b/activerecord/test/models/ship_part.rb
@@ -2,6 +2,7 @@ class ShipPart < ActiveRecord::Base
   belongs_to :ship
   has_many :trinkets, :class_name => "Treasure", :as => :looter
   accepts_nested_attributes_for :trinkets, :allow_destroy => true
+  accepts_nested_attributes_for :ship
 
   validates_presence_of :name
-end
\ No newline at end of file
+end
diff --git a/activerecord/test/models/shop_account.rb b/activerecord/test/models/shop_account.rb
new file mode 100644
index 0000000000..1580e8b20c
--- /dev/null
+++ b/activerecord/test/models/shop_account.rb
@@ -0,0 +1,6 @@
+class ShopAccount < ActiveRecord::Base
+  belongs_to :customer
+  belongs_to :customer_carrier
+
+  has_one :carrier, through: :customer_carrier
+end
diff --git a/activerecord/test/models/topic.rb b/activerecord/test/models/topic.rb
index f81ffe1d90..176bc79dc7 100644
--- a/activerecord/test/models/topic.rb
+++ b/activerecord/test/models/topic.rb
@@ -32,7 +32,7 @@ class Topic < ActiveRecord::Base
     end
   end
 
-  has_many :replies, :dependent => :destroy, :foreign_key => "parent_id"
+  has_many :replies, dependent: :destroy, foreign_key: "parent_id", autosave: true
   has_many :approved_replies, -> { approved }, class_name: 'Reply', foreign_key: "parent_id", counter_cache: 'replies_count'
 
   has_many :unique_replies, :dependent => :destroy, :foreign_key => "parent_id"
@@ -86,7 +86,7 @@ class Topic < ActiveRecord::Base
     end
 
     def destroy_children
-      self.class.delete_all "parent_id = #{id}"
+      self.class.where("parent_id = #{id}").delete_all
     end
 
     def set_email_address
diff --git a/activerecord/test/models/treasure.rb b/activerecord/test/models/treasure.rb
index a69d3fd3df..63ff0c23ec 100644
--- a/activerecord/test/models/treasure.rb
+++ b/activerecord/test/models/treasure.rb
@@ -1,6 +1,8 @@
 class Treasure < ActiveRecord::Base
   has_and_belongs_to_many :parrots
   belongs_to :looter, :polymorphic => true
+  # No counter_cache option given
+  belongs_to :ship
 
   has_many :price_estimates, :as => :estimate_of
   has_and_belongs_to_many :rich_people, join_table: 'peoples_treasures', validate: false
diff --git a/activerecord/test/models/tree.rb b/activerecord/test/models/tree.rb
new file mode 100644
index 0000000000..dc29cccc9c
--- /dev/null
+++ b/activerecord/test/models/tree.rb
@@ -0,0 +1,3 @@
+class Tree < ActiveRecord::Base
+  has_many :nodes, dependent: :destroy
+end
diff --git a/activerecord/test/models/tuning_peg.rb b/activerecord/test/models/tuning_peg.rb
new file mode 100644
index 0000000000..1252d6dc1d
--- /dev/null
+++ b/activerecord/test/models/tuning_peg.rb
@@ -0,0 +1,4 @@
+class TuningPeg < ActiveRecord::Base
+  belongs_to :guitar
+  validates_numericality_of :pitch
+end
diff --git a/activerecord/test/models/user.rb b/activerecord/test/models/user.rb
index 23cd2e0e1c..f5dc93e994 100644
--- a/activerecord/test/models/user.rb
+++ b/activerecord/test/models/user.rb
@@ -2,3 +2,7 @@ class User < ActiveRecord::Base
   has_secure_token
   has_secure_token :auth_token
 end
+
+class UserWithNotification < User
+  after_create -> { Notification.create! message: "A new user has been created." }
+end
diff --git a/activerecord/test/models/vehicle.rb b/activerecord/test/models/vehicle.rb
new file mode 100644
index 0000000000..ef26170f1f
--- /dev/null
+++ b/activerecord/test/models/vehicle.rb
@@ -0,0 +1,7 @@
+class Vehicle < ActiveRecord::Base
+  self.abstract_class = true
+  default_scope -> { where("tires_count IS NOT NULL") }
+end
+
+class Bus < Vehicle
+end
\ No newline at end of file
diff --git a/activerecord/test/schema/mysql2_specific_schema.rb b/activerecord/test/schema/mysql2_specific_schema.rb
index a9a6514c9d..92e0b197a7 100644
--- a/activerecord/test/schema/mysql2_specific_schema.rb
+++ b/activerecord/test/schema/mysql2_specific_schema.rb
@@ -2,7 +2,7 @@ ActiveRecord::Schema.define do
   create_table :binary_fields, force: true do |t|
     t.binary :var_binary, limit: 255
     t.binary :var_binary_large, limit: 4095
-    t.column :tiny_blob, 'tinyblob', limit: 255
+    t.blob   :tiny_blob, limit: 255
     t.binary :normal_blob, limit: 65535
     t.binary :medium_blob, limit: 16777215
     t.binary :long_blob, limit: 2147483647
@@ -24,6 +24,11 @@ ActiveRecord::Schema.define do
   add_index :key_tests, :pizza, :using => :btree, :name => 'index_key_tests_on_pizza'
   add_index :key_tests, :snacks, :name => 'index_key_tests_on_snack'
 
+  create_table :collation_tests, id: false, force: true do |t|
+    t.string :string_cs_column, limit: 1, collation: 'utf8_bin'
+    t.string :string_ci_column, limit: 1, collation: 'utf8_general_ci'
+  end
+
   ActiveRecord::Base.connection.execute <<-SQL
 DROP PROCEDURE IF EXISTS ten;
 SQL
@@ -36,19 +41,17 @@ END
 SQL
 
   ActiveRecord::Base.connection.execute <<-SQL
-DROP TABLE IF EXISTS collation_tests;
+DROP PROCEDURE IF EXISTS topics;
 SQL
 
   ActiveRecord::Base.connection.execute <<-SQL
-CREATE TABLE collation_tests (
-  string_cs_column VARCHAR(1) COLLATE utf8_bin,
-  string_ci_column VARCHAR(1) COLLATE utf8_general_ci
-) CHARACTER SET utf8 COLLATE utf8_general_ci
+CREATE PROCEDURE topics(IN num INT) SQL SECURITY INVOKER
+BEGIN
+  select * from topics limit num;
+END
 SQL
 
-  ActiveRecord::Base.connection.execute <<-SQL
-DROP TABLE IF EXISTS enum_tests;
-SQL
+  ActiveRecord::Base.connection.drop_table "enum_tests", if_exists: true
 
   ActiveRecord::Base.connection.execute <<-SQL
 CREATE TABLE enum_tests (
diff --git a/activerecord/test/schema/mysql_specific_schema.rb b/activerecord/test/schema/mysql_specific_schema.rb
index f2cffca52c..553cb56103 100644
--- a/activerecord/test/schema/mysql_specific_schema.rb
+++ b/activerecord/test/schema/mysql_specific_schema.rb
@@ -2,7 +2,7 @@ ActiveRecord::Schema.define do
   create_table :binary_fields, force: true do |t|
     t.binary :var_binary, limit: 255
     t.binary :var_binary_large, limit: 4095
-    t.column :tiny_blob, 'tinyblob', limit: 255
+    t.blob   :tiny_blob, limit: 255
     t.binary :normal_blob, limit: 65535
     t.binary :medium_blob, limit: 16777215
     t.binary :long_blob, limit: 2147483647
@@ -24,6 +24,11 @@ ActiveRecord::Schema.define do
   add_index :key_tests, :pizza, :using => :btree, :name => 'index_key_tests_on_pizza'
   add_index :key_tests, :snacks, :name => 'index_key_tests_on_snack'
 
+  create_table :collation_tests, id: false, force: true do |t|
+    t.string :string_cs_column, limit: 1, collation: 'utf8_bin'
+    t.string :string_ci_column, limit: 1, collation: 'utf8_general_ci'
+  end
+
   ActiveRecord::Base.connection.execute <<-SQL
 DROP PROCEDURE IF EXISTS ten;
 SQL
@@ -40,26 +45,13 @@ DROP PROCEDURE IF EXISTS topics;
 SQL
 
   ActiveRecord::Base.connection.execute <<-SQL
-CREATE PROCEDURE topics() SQL SECURITY INVOKER
+CREATE PROCEDURE topics(IN num INT) SQL SECURITY INVOKER
 BEGIN
-	select * from topics limit 1;
+  select * from topics limit num;
 END
 SQL
 
-  ActiveRecord::Base.connection.execute <<-SQL
-DROP TABLE IF EXISTS collation_tests;
-SQL
-
-  ActiveRecord::Base.connection.execute <<-SQL
-CREATE TABLE collation_tests (
-  string_cs_column VARCHAR(1) COLLATE utf8_bin,
-  string_ci_column VARCHAR(1) COLLATE utf8_general_ci
-) CHARACTER SET utf8 COLLATE utf8_general_ci
-SQL
-
-  ActiveRecord::Base.connection.execute <<-SQL
-DROP TABLE IF EXISTS enum_tests;
-SQL
+  ActiveRecord::Base.connection.drop_table "enum_tests", if_exists: true
 
   ActiveRecord::Base.connection.execute <<-SQL
 CREATE TABLE enum_tests (
diff --git a/activerecord/test/schema/postgresql_specific_schema.rb b/activerecord/test/schema/postgresql_specific_schema.rb
index 55360b9aa2..df0362573b 100644
--- a/activerecord/test/schema/postgresql_specific_schema.rb
+++ b/activerecord/test/schema/postgresql_specific_schema.rb
@@ -1,8 +1,19 @@
 ActiveRecord::Schema.define do
 
+  enable_extension!('uuid-ossp', ActiveRecord::Base.connection)
+
+  create_table :uuid_parents, id: :uuid, force: true do |t|
+    t.string :name
+  end
+
+  create_table :uuid_children, id: :uuid, force: true do |t|
+    t.string :name
+    t.uuid :uuid_parent_id
+  end
+
   %w(postgresql_times postgresql_oids defaults postgresql_timestamp_with_zones
       postgresql_partitioned_table postgresql_partitioned_table_parent).each do |table_name|
-    execute "DROP TABLE IF EXISTS #{quote_table_name table_name}"
+    drop_table table_name, if_exists: true
   end
 
   execute 'DROP SEQUENCE IF EXISTS companies_nonstd_seq CASCADE'
@@ -88,19 +99,14 @@ _SQL
     end
   end
 
-  begin
-    execute <<_SQL
-    CREATE TABLE postgresql_xml_data_type (
-    id SERIAL PRIMARY KEY,
-    data xml
-    );
-_SQL
-  rescue #This version of PostgreSQL either has no XML support or is was not compiled with XML support: skipping table
-  end
-
   # This table is to verify if the :limit option is being ignored for text and binary columns
   create_table :limitless_fields, force: true do |t|
     t.binary :binary, limit: 100_000
     t.text :text, limit: 100_000
   end
+
+  create_table :bigint_array, force: true do |t|
+    t.integer :big_int_data_points, limit: 8, array: true
+    t.decimal :decimal_array_default, array: true, default: [1.23, 3.45]
+  end
 end
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index 477afe6feb..66a1f5aa8a 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 ActiveRecord::Schema.define do
   def except(adapter_names_to_exclude)
     unless [adapter_names_to_exclude].flatten.include?(adapter_name)
@@ -7,20 +5,6 @@ ActiveRecord::Schema.define do
     end
   end
 
-  #put adapter specific setup here
-  case adapter_name
-  when "PostgreSQL"
-    enable_extension!('uuid-ossp', ActiveRecord::Base.connection)
-    create_table :uuid_parents, id: :uuid, force: true do |t|
-      t.string :name
-    end
-    create_table :uuid_children, id: :uuid, force: true do |t|
-      t.string :name
-      t.uuid :uuid_parent_id
-    end
-  end
-
-
   # ------------------------------------------------------------------- #
   #                                                                     #
   #   Please keep these create table statements in alphabetical order   #
@@ -52,6 +36,7 @@ ActiveRecord::Schema.define do
 
   create_table :aircraft, force: true do |t|
     t.string :name
+    t.integer :wheels_count, default: 0, null: false
   end
 
   create_table :articles, force: true do |t|
@@ -115,6 +100,10 @@ ActiveRecord::Schema.define do
     t.column :status, :integer, default: 0
     t.column :read_status, :integer, default: 0
     t.column :nullable_status, :integer
+    t.column :language, :integer, default: 0
+    t.column :author_visibility, :integer, default: 0
+    t.column :illustrator_visibility, :integer, default: 0
+    t.column :font_size, :integer, default: 0
   end
 
   create_table :booleans, force: true do |t|
@@ -141,6 +130,8 @@ ActiveRecord::Schema.define do
     t.timestamps null: false
   end
 
+  create_table :carriers, force: true
+
   create_table :categories, force: true do |t|
     t.string :name, null: false
     t.string :type
@@ -255,6 +246,11 @@ ActiveRecord::Schema.define do
     t.string  :gps_location
   end
 
+  create_table :customer_carriers, force: true do |t|
+    t.references :customer
+    t.references :carrier
+  end
+
   create_table :dashboards, force: true, id: false do |t|
     t.string :dashboard_id
     t.string :name
@@ -262,11 +258,21 @@ ActiveRecord::Schema.define do
 
   create_table :developers, force: true do |t|
     t.string   :name
+    t.string   :first_name
     t.integer  :salary, default: 70000
-    t.datetime :created_at
-    t.datetime :updated_at
-    t.datetime :created_on
-    t.datetime :updated_on
+    t.integer :firm_id
+    t.integer :mentor_id
+    if subsecond_precision_supported?
+      t.datetime :created_at, precision: 6
+      t.datetime :updated_at, precision: 6
+      t.datetime :created_on, precision: 6
+      t.datetime :updated_on, precision: 6
+    else
+      t.datetime :created_at
+      t.datetime :updated_at
+      t.datetime :created_on
+      t.datetime :updated_on
+    end
   end
 
   create_table :developers_projects, force: true, id: false do |t|
@@ -289,6 +295,11 @@ ActiveRecord::Schema.define do
     t.string  :alias
   end
 
+  create_table :doubloons, force: true do |t|
+    t.integer :pirate_id
+    t.integer :weight
+  end
+
   create_table :edges, force: true, id: false do |t|
     t.column :source_id, :integer, null: false
     t.column :sink_id,   :integer, null: false
@@ -345,6 +356,10 @@ ActiveRecord::Schema.define do
     t.column :key, :string
   end
 
+  create_table :guitar, force: true do |t|
+    t.string :color
+  end
+
   create_table :inept_wizards, force: true do |t|
     t.column :name, :string, null: false
     t.column :city, :string, null: false
@@ -360,7 +375,11 @@ ActiveRecord::Schema.define do
 
   create_table :invoices, force: true do |t|
     t.integer :balance
-    t.datetime :updated_at
+    if subsecond_precision_supported?
+      t.datetime :updated_at, precision: 6
+    else
+      t.datetime :updated_at
+    end
   end
 
   create_table :iris, force: true do |t|
@@ -446,6 +465,10 @@ ActiveRecord::Schema.define do
     t.string :name
   end
 
+  create_table :mentors, force: true do |t|
+    t.string :name
+  end
+
   create_table :minivans, force: true, id: false do |t|
     t.string :minivan_id
     t.string :name
@@ -477,6 +500,10 @@ ActiveRecord::Schema.define do
     t.string      :name
   end
 
+  create_table :notifications, force: true do |t|
+    t.string :message
+  end
+
   create_table :numeric_data, force: true do |t|
     t.decimal :bank_balance, precision: 10, scale: 2
     t.decimal :big_bank_balance, precision: 15, scale: 2
@@ -506,7 +533,11 @@ ActiveRecord::Schema.define do
 
   create_table :owners, primary_key: :owner_id, force: true do |t|
     t.string :name
-    t.column :updated_at, :datetime
+    if subsecond_precision_supported?
+      t.column :updated_at, :datetime, precision: 6
+    else
+      t.column :updated_at, :datetime
+    end
     t.column :happy_at,   :datetime
     t.string :essay_id
   end
@@ -524,10 +555,17 @@ ActiveRecord::Schema.define do
     t.column :color, :string
     t.column :parrot_sti_class, :string
     t.column :killer_id, :integer
-    t.column :created_at, :datetime
-    t.column :created_on, :datetime
-    t.column :updated_at, :datetime
-    t.column :updated_on, :datetime
+    if subsecond_precision_supported?
+      t.column :created_at, :datetime, precision: 0
+      t.column :created_on, :datetime, precision: 0
+      t.column :updated_at, :datetime, precision: 0
+      t.column :updated_on, :datetime, precision: 0
+    else
+      t.column :created_at, :datetime
+      t.column :created_on, :datetime
+      t.column :updated_at, :datetime
+      t.column :updated_on, :datetime
+    end
   end
 
   create_table :parrots_pirates, id: false, force: true do |t|
@@ -570,15 +608,24 @@ ActiveRecord::Schema.define do
   create_table :pets, primary_key: :pet_id, force: true do |t|
     t.string :name
     t.integer :owner_id, :integer
-    t.timestamps null: false
+    if subsecond_precision_supported?
+      t.timestamps null: false, precision: 6
+    else
+      t.timestamps null: false
+    end
   end
 
   create_table :pirates, force: true do |t|
     t.column :catchphrase, :string
     t.column :parrot_id, :integer
     t.integer :non_validated_parrot_id
-    t.column :created_on, :datetime
-    t.column :updated_on, :datetime
+    if subsecond_precision_supported?
+      t.column :created_on, :datetime, precision: 6
+      t.column :updated_on, :datetime, precision: 6
+    else
+      t.column :created_on, :datetime
+      t.column :updated_on, :datetime
+    end
   end
 
   create_table :posts, force: true do |t|
@@ -629,9 +676,21 @@ ActiveRecord::Schema.define do
   create_table :projects, force: true do |t|
     t.string :name
     t.string :type
+    t.integer :firm_id
+    t.integer :mentor_id
+  end
+
+  create_table :randomly_named_table1, force: true do |t|
+    t.string  :some_attribute
+    t.integer :another_attribute
+  end
+
+  create_table :randomly_named_table2, force: true do |t|
+    t.string  :some_attribute
+    t.integer :another_attribute
   end
 
-  create_table :randomly_named_table, force: true do |t|
+  create_table :randomly_named_table3, force: true do |t|
     t.string  :some_attribute
     t.integer :another_attribute
   end
@@ -665,7 +724,10 @@ ActiveRecord::Schema.define do
   create_table :ships, force: true do |t|
     t.string :name
     t.integer :pirate_id
+    t.belongs_to :developer
     t.integer :update_only_pirate_id
+    # Conventionally named column for counter_cache
+    t.integer :treasures_count, default: 0
     t.datetime :created_at
     t.datetime :created_on
     t.datetime :updated_at
@@ -675,6 +737,20 @@ ActiveRecord::Schema.define do
   create_table :ship_parts, force: true do |t|
     t.string :name
     t.integer :ship_id
+    if subsecond_precision_supported?
+      t.datetime :updated_at, precision: 6
+    else
+      t.datetime :updated_at
+    end
+  end
+
+  create_table :prisoners, force: true do |t|
+    t.belongs_to :ship
+  end
+
+  create_table :shop_accounts, force: true do |t|
+    t.references :customer
+    t.references :customer_carrier
   end
 
   create_table :speedometers, force: true, id: false do |t|
@@ -735,7 +811,7 @@ ActiveRecord::Schema.define do
     t.string   :title, limit: 250
     t.string   :author_name
     t.string   :author_email_address
-    if mysql_56?
+    if subsecond_precision_supported?
       t.datetime :written_on, precision: 6
     else
       t.datetime :written_on
@@ -758,7 +834,11 @@ ActiveRecord::Schema.define do
     t.string   :parent_title
     t.string   :type
     t.string   :group
-    t.timestamps null: true
+    if subsecond_precision_supported?
+      t.timestamps null: true, precision: 6
+    else
+      t.timestamps null: true
+    end
   end
 
   create_table :toys, primary_key: :toy_id, force: true do |t|
@@ -780,6 +860,12 @@ ActiveRecord::Schema.define do
     t.column :type, :string
     t.column :looter_id, :integer
     t.column :looter_type, :string
+    t.belongs_to :ship
+  end
+
+  create_table :tuning_pegs, force: true do |t|
+    t.integer :guitar_id
+    t.float :pitch
   end
 
   create_table :tyres, force: true do |t|
@@ -865,6 +951,17 @@ ActiveRecord::Schema.define do
     t.string 'from'
   end
 
+  create_table :nodes, force: true do |t|
+    t.integer :tree_id
+    t.integer :parent_id
+    t.string :name
+    t.datetime :updated_at
+  end
+  create_table :trees, force: true do |t|
+    t.string :name
+    t.datetime :updated_at
+  end
+
   create_table :hotels, force: true do |t|
   end
   create_table :departments, force: true do |t|
@@ -879,6 +976,10 @@ ActiveRecord::Schema.define do
     t.string :employable_type
     t.integer :department_id
   end
+  create_table :recipes, force: true do |t|
+    t.integer :chef_id
+    t.integer :hotel_id
+  end
 
   create_table :records, force: true do |t|
   end
@@ -907,6 +1008,10 @@ ActiveRecord::Schema.define do
     t.string :token
     t.string :auth_token
   end
+
+  create_table :test_with_keyword_column_name, force: true do |t|
+    t.string :desc
+  end
 end
 
 Course.connection.create_table :courses, force: true do |t|
@@ -917,3 +1022,12 @@ end
 College.connection.create_table :colleges, force: true do |t|
   t.column :name, :string, null: false
 end
+
+Professor.connection.create_table :professors, force: true do |t|
+  t.column :name, :string, null: false
+end
+
+Professor.connection.create_table :courses_professors, id: false, force: true do |t|
+  t.references :course
+  t.references :professor
+end
diff --git a/activerecord/test/support/connection.rb b/activerecord/test/support/connection.rb
index d11fd9cfc1..c5334e8596 100644
--- a/activerecord/test/support/connection.rb
+++ b/activerecord/test/support/connection.rb
@@ -1,6 +1,7 @@
 require 'active_support/logger'
 require 'models/college'
 require 'models/course'
+require 'models/professor'
 
 module ARTest
   def self.connection_name
diff --git a/activerecord/test/support/yaml_compatibility_fixtures/rails_4_1.yml b/activerecord/test/support/yaml_compatibility_fixtures/rails_4_1.yml
new file mode 100644
index 0000000000..20b128db9c
--- /dev/null
+++ b/activerecord/test/support/yaml_compatibility_fixtures/rails_4_1.yml
@@ -0,0 +1,22 @@
+--- !ruby/object:Topic
+  attributes:
+    id: 
+    title: The First Topic
+    author_name: David
+    author_email_address: david@loudthinking.com
+    written_on: 2003-07-16 14:28:11.223300000 Z
+    bonus_time: 2000-01-01 14:28:00.000000000 Z
+    last_read: 2004-04-15
+    content: |
+      ---
+      :omg: :lol
+    important: 
+    approved: false
+    replies_count: 1
+    unique_replies_count: 0
+    parent_id: 
+    parent_title: 
+    type: 
+    group: 
+    created_at: 2015-03-10 17:05:42.000000000 Z
+    updated_at: 2015-03-10 17:05:42.000000000 Z
diff --git a/activerecord/test/support/yaml_compatibility_fixtures/rails_4_2_0.yml b/activerecord/test/support/yaml_compatibility_fixtures/rails_4_2_0.yml
new file mode 100644
index 0000000000..b3d3b33141
--- /dev/null
+++ b/activerecord/test/support/yaml_compatibility_fixtures/rails_4_2_0.yml
@@ -0,0 +1,182 @@
+--- !ruby/object:Topic
+raw_attributes:
+  id: 1
+  title: The First Topic
+  author_name: David
+  author_email_address: david@loudthinking.com
+  written_on: '2003-07-16 14:28:11.223300'
+  bonus_time: '2005-01-30 14:28:00.000000'
+  last_read: '2004-04-15'
+  content: |
+    --- Have a nice day
+    ...
+  important:
+  approved: f
+  replies_count: 1
+  unique_replies_count: 0
+  parent_id:
+  parent_title:
+  type:
+  group:
+  created_at: '2015-03-10 17:44:41'
+  updated_at: '2015-03-10 17:44:41'
+attributes: !ruby/object:ActiveRecord::AttributeSet
+  attributes: !ruby/object:ActiveRecord::LazyAttributeHash
+    types:
+      id: &5 !ruby/object:ActiveRecord::Type::Integer
+        precision:
+        scale:
+        limit:
+        range: !ruby/range
+          begin: -2147483648
+          end: 2147483648
+          excl: true
+      title: &6 !ruby/object:ActiveRecord::Type::String
+        precision:
+        scale:
+        limit: 250
+      author_name: &1 !ruby/object:ActiveRecord::Type::String
+        precision:
+        scale:
+        limit:
+      author_email_address: *1
+      written_on: &4 !ruby/object:ActiveRecord::Type::DateTime
+        precision:
+        scale:
+        limit:
+      bonus_time: &7 !ruby/object:ActiveRecord::Type::Time
+        precision:
+        scale:
+        limit:
+      last_read: &8 !ruby/object:ActiveRecord::Type::Date
+        precision:
+        scale:
+        limit:
+      content: !ruby/object:ActiveRecord::Type::Serialized
+        coder: &9 !ruby/object:ActiveRecord::Coders::YAMLColumn
+          object_class: !ruby/class 'Object'
+        subtype: &2 !ruby/object:ActiveRecord::Type::Text
+          precision:
+          scale:
+          limit:
+      important: *2
+      approved: &10 !ruby/object:ActiveRecord::Type::Boolean
+        precision:
+        scale:
+        limit:
+      replies_count: &3 !ruby/object:ActiveRecord::Type::Integer
+        precision:
+        scale:
+        limit:
+        range: !ruby/range
+          begin: -2147483648
+          end: 2147483648
+          excl: true
+      unique_replies_count: *3
+      parent_id: *3
+      parent_title: *1
+      type: *1
+      group: *1
+      created_at: *4
+      updated_at: *4
+    values:
+      id: 1
+      title: The First Topic
+      author_name: David
+      author_email_address: david@loudthinking.com
+      written_on: '2003-07-16 14:28:11.223300'
+      bonus_time: '2005-01-30 14:28:00.000000'
+      last_read: '2004-04-15'
+      content: |
+        --- Have a nice day
+        ...
+      important:
+      approved: f
+      replies_count: 1
+      unique_replies_count: 0
+      parent_id:
+      parent_title:
+      type:
+      group:
+      created_at: '2015-03-10 17:44:41'
+      updated_at: '2015-03-10 17:44:41'
+    additional_types: {}
+    materialized: true
+    delegate_hash:
+      id: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: id
+        value_before_type_cast: 1
+        type: *5
+      title: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: title
+        value_before_type_cast: The First Topic
+        type: *6
+      author_name: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: author_name
+        value_before_type_cast: David
+        type: *1
+      author_email_address: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: author_email_address
+        value_before_type_cast: david@loudthinking.com
+        type: *1
+      written_on: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: written_on
+        value_before_type_cast: '2003-07-16 14:28:11.223300'
+        type: *4
+      bonus_time: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: bonus_time
+        value_before_type_cast: '2005-01-30 14:28:00.000000'
+        type: *7
+      last_read: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: last_read
+        value_before_type_cast: '2004-04-15'
+        type: *8
+      content: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: content
+        value_before_type_cast: |
+          --- Have a nice day
+          ...
+        type: !ruby/object:ActiveRecord::Type::Serialized
+          coder: *9
+          subtype: *2
+      important: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: important
+        value_before_type_cast:
+        type: *2
+      approved: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: approved
+        value_before_type_cast: f
+        type: *10
+      replies_count: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: replies_count
+        value_before_type_cast: 1
+        type: *3
+      unique_replies_count: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: unique_replies_count
+        value_before_type_cast: 0
+        type: *3
+      parent_id: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: parent_id
+        value_before_type_cast:
+        type: *3
+      parent_title: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: parent_title
+        value_before_type_cast:
+        type: *1
+      type: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: type
+        value_before_type_cast:
+        type: *1
+      group: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: group
+        value_before_type_cast:
+        type: *1
+      created_at: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: created_at
+        value_before_type_cast: '2015-03-10 17:44:41'
+        type: *4
+      updated_at: !ruby/object:ActiveRecord::Attribute::FromDatabase
+        name: updated_at
+        value_before_type_cast: '2015-03-10 17:44:41'
+        type: *4
+new_record: false
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index f6c236bc35..3705fc57fc 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,267 @@
+*   Change Integer#year to return a Fixnum instead of a Float to improve
+    consistency.
+
+    Integer#years returned a Float while the rest of the accompanying methods
+    (days, weeks, months, etc.) return a Fixnum.
+
+    Before:
+
+    1.year # => 31557600.0
+
+    After:
+
+    1.year # => 31557600
+
+    *Konstantinos Rousis*
+
+*   Handle invalid UTF-8 strings when HTML escaping
+
+    Use `ActiveSupport::Multibyte::Unicode.tidy_bytes` to handle invalid UTF-8
+    strings in `ERB::Util.unwrapped_html_escape` and `ERB::Util.html_escape_once`.
+    Prevents user-entered input passed from a querystring into a form field from
+    causing invalid byte sequence errors.
+
+    *Grey Baker*
+
+*   Update `ActiveSupport::Multibyte::Chars#slice!` to return `nil` if the
+    arguments are out of bounds, to mirror the behavior of `String#slice!`
+
+    *Gourav Tiwari*
+
+*   Fix `number_to_human` so that 999999999 rounds to "1 Billion" instead of
+    "1000 Million".
+
+    *Max Jacobson*
+
+*   Fix `ActiveSupport::Deprecation#deprecate_methods` to report using the
+    current deprecator instance, where applicable.
+
+    *Brandon Dunne*
+
+*   `Cache#fetch` instrumentation marks whether it was a `:hit`.
+
+    *Robin Clowers*
+
+*   `assert_difference` and `assert_no_difference` now returns the result of the
+    yielded block.
+
+    Example:
+
+      post = assert_difference -> { Post.count }, 1 do
+        Post.create
+      end
+
+    *Lucas Mazza*
+
+*   Short-circuit `blank?` on date and time values since they are never blank.
+
+    Fixes #21657
+
+    *Andrew White*
+
+*   Replaced deprecated `ThreadSafe::Cache` with its successor `Concurrent::Map` now that
+    the thread_safe gem has been merged into concurrent-ruby.
+
+    *Jerry D'Antonio*
+
+*   Updated Unicode version to 8.0.0
+
+    *Anshul Sharma*
+
+*   `number_to_currency` and `number_with_delimiter` now accept custom `delimiter_pattern` option
+     to handle placement of delimiter, to support currency formats like INR
+
+     Example:
+
+        number_to_currency(1230000, delimiter_pattern: /(\d+?)(?=(\d\d)+(\d)(?!\d))/, unit: '₹', format: "%u %n")
+        # => '₹ 12,30,000.00'
+
+    *Vipul A M*
+
+*   Deprecate `:prefix` option of `number_to_human_size` with no replacement.
+
+    *Jean Boussier*
+
+*   Fix `TimeWithZone#eql?` to properly handle `TimeWithZone` created from `DateTime`:
+        twz = DateTime.now.in_time_zone
+        twz.eql?(twz.dup) => true
+
+    Fixes #14178.
+
+    *Roque Pinel*
+
+*   ActiveSupport::HashWithIndifferentAccess `select` and `reject` will now return
+    enumerator if called without block.
+
+    Fixes #20095
+
+    *Bernard Potocki*
+
+*   Removed `ActiveSupport::Concurrency::Latch`, superseded by `Concurrent::CountDownLatch`
+    from the concurrent-ruby gem.
+
+    *Jerry D'Antonio*
+
+*   Fix not calling `#default` on `HashWithIndifferentAccess#to_hash` when only
+    `default_proc` is set, which could raise.
+
+    *Simon Eskildsen*
+
+*   Fix setting `default_proc` on `HashWithIndifferentAccess#dup`
+
+    *Simon Eskildsen*
+
+*   Fix a range of values for parameters of the Time#change
+
+    *Nikolay Kondratyev*
+
+*   Add `Enumerable#pluck` to get the same values from arrays as from ActiveRecord
+    associations.
+
+    Fixes #20339.
+
+    *Kevin Deisz*
+
+*   Add a bang version to `ActiveSupport::OrderedOptions` get methods which will raise
+    an `KeyError` if the value is `.blank?`
+
+    Before:
+
+        if (slack_url = Rails.application.secrets.slack_url).present?
+          # Do something worthwhile
+        else
+          # Raise as important secret password is not specified
+        end
+
+    After:
+
+        slack_url = Rails.application.secrets.slack_url!
+
+    *Aditya Sanghi*, *Gaurish Sharma*
+
+*   Remove deprecated `Class#superclass_delegating_accessor`.
+    Use `Class#class_attribute` instead.
+
+    *Akshay Vishnoi*
+
+*   Patch `Delegator` to work with `#try`.
+
+    Fixes #5790.
+
+    *Nate Smith*
+
+*   Add `Integer#positive?` and `Integer#negative?` query methods
+    in the vein of `Fixnum#zero?`.
+
+    This makes it nicer to do things like `bunch_of_numbers.select(&:positive?)`.
+
+    *DHH*
+
+*   Encoding `ActiveSupport::TimeWithZone` to YAML now preserves the timezone information.
+
+    Fixes #9183.
+
+    *Andrew White*
+
+*   Added `ActiveSupport::TimeZone#strptime` to allow parsing times as if
+    from a given timezone.
+
+    *Paul A Jungwirth*
+
+*   `ActiveSupport::Callbacks#skip_callback` now raises an `ArgumentError` if
+    an unrecognized callback is removed.
+
+    *Iain Beeston*
+
+*   Added `ActiveSupport::ArrayInquirer` and `Array#inquiry`.
+
+    Wrapping an array in an `ArrayInquirer` gives a friendlier way to check its
+    contents:
+
+        variants = ActiveSupport::ArrayInquirer.new([:phone, :tablet])
+
+        variants.phone?    # => true
+        variants.tablet?   # => true
+        variants.desktop?  # => false
+
+        variants.any?(:phone, :tablet)   # => true
+        variants.any?(:phone, :desktop)  # => true
+        variants.any?(:desktop, :watch)  # => false
+
+    `Array#inquiry` is a shortcut for wrapping the receiving array in an
+    `ArrayInquirer`.
+
+    *George Claghorn*
+
+*   Deprecate `alias_method_chain` in favour of `Module#prepend` introduced in
+    Ruby 2.0.
+
+    *Kir Shatrov*
+
+*   Added `#without` on `Enumerable` and `Array` to return a copy of an
+    enumerable without the specified elements.
+
+    *Todd Bealmear*
+
+*   Fixed a problem where `String#truncate_words` would get stuck with a complex
+    string.
+
+    *Henrik Nygren*
+
+*   Fixed a roundtrip problem with `AS::SafeBuffer` where primitive-like strings
+    will be dumped as primitives:
+
+    Before:
+
+        YAML.load ActiveSupport::SafeBuffer.new("Hello").to_yaml  # => "Hello"
+        YAML.load ActiveSupport::SafeBuffer.new("true").to_yaml   # => true
+        YAML.load ActiveSupport::SafeBuffer.new("false").to_yaml  # => false
+        YAML.load ActiveSupport::SafeBuffer.new("1").to_yaml      # => 1
+        YAML.load ActiveSupport::SafeBuffer.new("1.1").to_yaml    # => 1.1
+
+    After:
+
+        YAML.load ActiveSupport::SafeBuffer.new("Hello").to_yaml  # => "Hello"
+        YAML.load ActiveSupport::SafeBuffer.new("true").to_yaml   # => "true"
+        YAML.load ActiveSupport::SafeBuffer.new("false").to_yaml  # => "false"
+        YAML.load ActiveSupport::SafeBuffer.new("1").to_yaml      # => "1"
+        YAML.load ActiveSupport::SafeBuffer.new("1.1").to_yaml    # => "1.1"
+
+    *Godfrey Chan*
+
+*   Enable `number_to_percentage` to keep the number's precision by allowing
+    `:precision` to be `nil`.
+
+    *Jack Xu*
+
+*   `config_accessor` became a private method, as with Ruby's `attr_accessor`.
+
+    *Akira Matsuda*
+
+*   `AS::Testing::TimeHelpers#travel_to` now changes `DateTime.now` as well as
+    `Time.now` and `Date.today`.
+
+    *Yuki Nishijima*
+
+*   Add `file_fixture` to `ActiveSupport::TestCase`.
+    It provides a simple mechanism to access sample files in your test cases.
+
+    By default file fixtures are stored in `test/fixtures/files`. This can be
+    configured per test-case using the `file_fixture_path` class attribute.
+
+    *Yves Senn*
+
+*   Return value of yielded block in `File.atomic_write`.
+
+    *Ian Ker-Seymer*
+
+*   Duplicate frozen array when assigning it to a `HashWithIndifferentAccess` so
+    that it doesn't raise a `RuntimeError` when calling `map!` on it in `convert_value`.
+
+    Fixes #18550.
+
+    *Aditya Kapoor*
+
 *   Add missing time zone definitions for Russian Federation and sync them
     with `zone.tab` file from tzdata version 2014j (latest).
 
@@ -20,7 +284,7 @@
 *   Add `#on_weekend?`, `#next_weekday`, `#prev_weekday` methods to `Date`,
     `Time`, and `DateTime`.
 
-    `#on_weekend?` returns true if the receiving date/time falls on a Saturday
+    `#on_weekend?` returns `true` if the receiving date/time falls on a Saturday
     or Sunday.
 
     `#next_weekday` returns a new date/time representing the next day that does
@@ -68,32 +332,26 @@
 
     The preferred method to halt a callback chain from now on is to explicitly
     `throw(:abort)`.
-    In the past, returning `false` in an ActiveSupport callback had the side
-    effect of halting the callback chain. This is not recommended anymore and,
-    depending on the value of
-    `Callbacks::CallbackChain.halt_and_display_warning_on_return_false`, will
-    either not work at all or display a deprecation warning.
-
-*   Add Callbacks::CallbackChain.halt_and_display_warning_on_return_false
+    In the past, callbacks could only be halted by explicitly providing a
+    terminator and by having a callback match the conditions of the terminator.
 
-    Setting `Callbacks::CallbackChain.halt_and_display_warning_on_return_false`
-    to true will let an app support the deprecated way of halting callback
-    chains by returning `false`.
+*   Add `ActiveSupport.halt_callback_chains_on_return_false`
 
-    Setting the value to false will tell the app to ignore any `false` value
-    returned by callbacks, and only halt the chain upon `throw(:abort)`.
+    Setting `ActiveSupport.halt_callback_chains_on_return_false`
+    to `true` will let an app support the deprecated way of halting Active Record,
+    and Active Model callback chains by returning `false`.
 
-    The value can also be set with the Rails configuration option
-    `config.active_support.halt_callback_chains_on_return_false`.
+    Setting the value to `false` will tell the app to ignore any `false` value
+    returned by those callbacks, and only halt the chain upon `throw(:abort)`.
 
     When the configuration option is missing, its value is `true`, so older apps
     ported to Rails 5.0 will not break (but display a deprecation warning).
     For new Rails 5.0 apps, its value is set to `false` in an initializer, so
     these apps will support the new behavior by default.
 
-    *claudiob*
+    *claudiob*, *Roque Pinel*
 
-*   Changes arguments and default value of CallbackChain's :terminator option
+*   Changes arguments and default value of CallbackChain's `:terminator` option
 
     Chains of callbacks defined without an explicit `:terminator` option will
     now be halted as soon as a `before_` callback throws `:abort`.
diff --git a/activesupport/README.rdoc b/activesupport/README.rdoc
index a6424a353a..cd72f53821 100644
--- a/activesupport/README.rdoc
+++ b/activesupport/README.rdoc
@@ -10,7 +10,7 @@ outside of Rails.
 
 The latest version of Active Support can be installed with RubyGems:
 
-  % [sudo] gem install activesupport
+  % gem install activesupport
 
 Source code can be downloaded as part of the Rails project on GitHub:
 
diff --git a/activesupport/Rakefile b/activesupport/Rakefile
index 7c40df8dc8..81c242d4b1 100644
--- a/activesupport/Rakefile
+++ b/activesupport/Rakefile
@@ -1,5 +1,4 @@
 require 'rake/testtask'
-require 'rubygems/package_task'
 
 task :default => :test
 Rake::TestTask.new do |t|
@@ -17,16 +16,3 @@ namespace :test do
     end or raise "Failures"
   end
 end
-
-spec = eval(File.read('activesupport.gemspec'))
-
-Gem::PackageTask.new(spec) do |p|
-  p.gem_spec = spec
-end
-
-desc "Release to rubygems"
-task :release => :package do
-  require 'rake/gemcutter'
-  Rake::Gemcutter::Tasks.new(spec).define
-  Rake::Task['gem:push'].invoke
-end
diff --git a/activesupport/activesupport.gemspec b/activesupport/activesupport.gemspec
index a5339e6475..93878518d7 100644
--- a/activesupport/activesupport.gemspec
+++ b/activesupport/activesupport.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'A toolkit of support libraries and Ruby core extensions extracted from the Rails framework.'
   s.description = 'A toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Rich support for multibyte strings, internationalization, time zones, and testing.'
 
-  s.required_ruby_version = '>= 2.2.0'
+  s.required_ruby_version = '>= 2.2.2'
 
   s.license = 'MIT'
 
@@ -24,5 +24,6 @@ Gem::Specification.new do |s|
   s.add_dependency 'json',       '~> 1.7', '>= 1.7.7'
   s.add_dependency 'tzinfo',     '~> 1.1'
   s.add_dependency 'minitest',   '~> 5.1'
-  s.add_dependency 'thread_safe','~> 0.3', '>= 0.3.4'
+  s.add_dependency 'concurrent-ruby', '~> 1.0.0.pre3', '< 2.0.0'
+  s.add_dependency 'method_source'
 end
diff --git a/activesupport/bin/test b/activesupport/bin/test
new file mode 100755
index 0000000000..404cabba51
--- /dev/null
+++ b/activesupport/bin/test
@@ -0,0 +1,4 @@
+#!/usr/bin/env ruby
+COMPONENT_ROOT = File.expand_path("../../", __FILE__)
+require File.expand_path("../tools/test", COMPONENT_ROOT)
+exit Minitest.run(ARGV)
diff --git a/activesupport/lib/active_support.rb b/activesupport/lib/active_support.rb
index 290920dbf8..63277a65b4 100644
--- a/activesupport/lib/active_support.rb
+++ b/activesupport/lib/active_support.rb
@@ -59,6 +59,7 @@ module ActiveSupport
     autoload :StringInquirer
     autoload :TaggedLogging
     autoload :XmlMini
+    autoload :ArrayInquirer
   end
 
   autoload :Rescuable
@@ -72,6 +73,14 @@ module ActiveSupport
   end
 
   cattr_accessor :test_order # :nodoc:
+
+  def self.halt_callback_chains_on_return_false
+    Callbacks.halt_and_display_warning_on_return_false
+  end
+
+  def self.halt_callback_chains_on_return_false=(value)
+    Callbacks.halt_and_display_warning_on_return_false = value
+  end
 end
 
 autoload :I18n, "active_support/i18n"
diff --git a/activesupport/lib/active_support/array_inquirer.rb b/activesupport/lib/active_support/array_inquirer.rb
new file mode 100644
index 0000000000..f59ddf5403
--- /dev/null
+++ b/activesupport/lib/active_support/array_inquirer.rb
@@ -0,0 +1,44 @@
+module ActiveSupport
+  # Wrapping an array in an +ArrayInquirer+ gives a friendlier way to check
+  # its string-like contents:
+  #
+  #   variants = ActiveSupport::ArrayInquirer.new([:phone, :tablet])
+  #
+  #   variants.phone?    # => true
+  #   variants.tablet?   # => true
+  #   variants.desktop?  # => false
+  class ArrayInquirer < Array
+    # Passes each element of +candidates+ collection to ArrayInquirer collection.
+    # The method returns true if at least one element is the same. If +candidates+
+    # collection is not given, method returns true.
+    #
+    #   variants = ActiveSupport::ArrayInquirer.new([:phone, :tablet])
+    #
+    #   variants.any?                      # => true
+    #   variants.any?(:phone, :tablet)     # => true
+    #   variants.any?('phone', 'desktop')  # => true
+    #   variants.any?(:desktop, :watch)    # => false
+    def any?(*candidates, &block)
+      if candidates.none?
+        super
+      else
+        candidates.any? do |candidate|
+          include?(candidate.to_sym) || include?(candidate.to_s)
+        end
+      end
+    end
+
+    private
+      def respond_to_missing?(name, include_private = false)
+        name[-1] == '?'
+      end
+
+      def method_missing(name, *args)
+        if name[-1] == '?'
+          any?(name[0..-2])
+        else
+          super
+        end
+      end
+  end
+end
diff --git a/activesupport/lib/active_support/backtrace_cleaner.rb b/activesupport/lib/active_support/backtrace_cleaner.rb
index d06f22ad5c..e161ec4cca 100644
--- a/activesupport/lib/active_support/backtrace_cleaner.rb
+++ b/activesupport/lib/active_support/backtrace_cleaner.rb
@@ -25,7 +25,7 @@ module ActiveSupport
   # of the backtrace, you can call <tt>BacktraceCleaner#remove_filters!</tt>
   # These two methods will give you a completely untouched backtrace.
   #
-  # Inspired by the Quiet Backtrace gem by Thoughtbot.
+  # Inspired by the Quiet Backtrace gem by thoughtbot.
   class BacktraceCleaner
     def initialize
       @filters, @silencers = [], []
diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index 3a1e1ac3a1..3996f583c2 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -26,7 +26,7 @@ module ActiveSupport
     end
 
     class << self
-      # Creates a new CacheStore object according to the given options.
+      # Creates a new Store object according to the given options.
       #
       # If no arguments are passed to this method, then a new
       # ActiveSupport::Cache::MemoryStore object will be returned.
@@ -277,13 +277,18 @@ module ActiveSupport
           options = merged_options(options)
           key = namespaced_key(name, options)
 
-          cached_entry = find_cached_entry(key, name, options) unless options[:force]
-          entry = handle_expired_entry(cached_entry, key, options)
+          instrument(:read, name, options) do |payload|
+            cached_entry = read_entry(key, options) unless options[:force]
+            payload[:super_operation] = :fetch if payload
+            entry = handle_expired_entry(cached_entry, key, options)
 
-          if entry
-            get_entry_value(entry, name, options)
-          else
-            save_block_result_to_cache(name, options) { |_name| yield _name }
+            if entry
+              payload[:hit] = true if payload
+              get_entry_value(entry, name, options)
+            else
+              payload[:hit] = false if payload
+              save_block_result_to_cache(name, options) { |_name| yield _name }
+            end
           end
         else
           read(name, options)
@@ -325,19 +330,22 @@ module ActiveSupport
       def read_multi(*names)
         options = names.extract_options!
         options = merged_options(options)
-        results = {}
-        names.each do |name|
-          key = namespaced_key(name, options)
-          entry = read_entry(key, options)
-          if entry
-            if entry.expired?
-              delete_entry(key, options)
-            else
-              results[name] = entry.value
+
+        instrument_multi(:read, names, options) do |payload|
+          results = {}
+          names.each do |name|
+            key = namespaced_key(name, options)
+            entry = read_entry(key, options)
+            if entry
+              if entry.expired?
+                delete_entry(key, options)
+              else
+                results[name] = entry.value
+              end
             end
           end
+          results
         end
-        results
       end
 
       # Fetches data from the cache, using the given keys. If there is data in
@@ -350,8 +358,11 @@ module ActiveSupport
       # Returns a hash with the data for each of the names. For example:
       #
       #   cache.write("bim", "bam")
-      #   cache.fetch_multi("bim", "boom") { |key| key * 2 }
-      #   # => { "bam" => "bam", "boom" => "boomboom" }
+      #   cache.fetch_multi("bim", "unknown_key") do |key|
+      #     "Fallback value for key: #{key}"
+      #   end
+      #   # => { "bim" => "bam",
+      #   #      "unknown_key" => "Fallback value for key: unknown_key" }
       #
       def fetch_multi(*names)
         options = names.extract_options!
@@ -527,31 +538,35 @@ module ActiveSupport
         end
 
         def instrument(operation, key, options = nil)
-          log(operation, key, options)
+          log { "Cache #{operation}: #{key}#{options.blank? ? "" : " (#{options.inspect})"}" }
 
           payload = { :key => key }
           payload.merge!(options) if options.is_a?(Hash)
           ActiveSupport::Notifications.instrument("cache_#{operation}.active_support", payload){ yield(payload) }
         end
 
-        def log(operation, key, options = nil)
-          return unless logger && logger.debug? && !silence?
-          logger.debug("Cache #{operation}: #{key}#{options.blank? ? "" : " (#{options.inspect})"}")
+        def instrument_multi(operation, keys, options = nil)
+          log do
+            formatted_keys = keys.map { |k| "- #{k}" }.join("\n")
+            "Caches multi #{operation}:\n#{formatted_keys}#{options.blank? ? "" : " (#{options.inspect})"}"
+          end
+
+          payload = { key: keys }
+          payload.merge!(options) if options.is_a?(Hash)
+          ActiveSupport::Notifications.instrument("cache_#{operation}_multi.active_support", payload) { yield(payload) }
         end
 
-        def find_cached_entry(key, name, options)
-          instrument(:read, name, options) do |payload|
-            payload[:super_operation] = :fetch if payload
-            read_entry(key, options)
-          end
+        def log
+          return unless logger && logger.debug? && !silence?
+          logger.debug(yield)
         end
 
         def handle_expired_entry(entry, key, options)
           if entry && entry.expired?
             race_ttl = options[:race_condition_ttl].to_i
-            if race_ttl && (Time.now.to_f - entry.expires_at <= race_ttl)
-              # When an entry has :race_condition_ttl defined, put the stale entry back into the cache
-              # for a brief period while the entry is begin recalculated.
+            if (race_ttl > 0) && (Time.now.to_f - entry.expires_at <= race_ttl)
+              # When an entry has a positive :race_condition_ttl defined, put the stale entry back into the cache
+              # for a brief period while the entry is being recalculated.
               entry.expires_at = Time.now + race_ttl
               write_entry(key, entry, :expires_in => race_ttl * 2)
             else
diff --git a/activesupport/lib/active_support/cache/file_store.rb b/activesupport/lib/active_support/cache/file_store.rb
index d08ecd2f7d..b7da30123a 100644
--- a/activesupport/lib/active_support/cache/file_store.rb
+++ b/activesupport/lib/active_support/cache/file_store.rb
@@ -29,6 +29,7 @@ module ActiveSupport
       def clear(options = nil)
         root_dirs = Dir.entries(cache_path).reject {|f| (EXCLUDED_DIRS + [".gitkeep"]).include?(f)}
         FileUtils.rm_r(root_dirs.collect{|f| File.join(cache_path, f)})
+      rescue Errno::ENOENT
       end
 
       # Preemptively iterates through all stored keys and removes the ones which have expired.
@@ -118,11 +119,12 @@ module ActiveSupport
 
         # Translate a key into a file path.
         def key_file_path(key)
-          if key.size > FILEPATH_MAX_SIZE
-            key = Digest::MD5.hexdigest(key)
+          fname = URI.encode_www_form_component(key)
+
+          if fname.size > FILEPATH_MAX_SIZE
+            fname = Digest::MD5.hexdigest(key)
           end
 
-          fname = URI.encode_www_form_component(key)
           hash = Zlib.adler32(fname)
           hash, dir_1 = hash.divmod(0x1000)
           dir_2 = hash.modulo(0x1000)
diff --git a/activesupport/lib/active_support/cache/mem_cache_store.rb b/activesupport/lib/active_support/cache/mem_cache_store.rb
index 61b4f0b8b0..47133bf550 100644
--- a/activesupport/lib/active_support/cache/mem_cache_store.rb
+++ b/activesupport/lib/active_support/cache/mem_cache_store.rb
@@ -26,7 +26,14 @@ module ActiveSupport
     class MemCacheStore < Store
       ESCAPE_KEY_CHARS = /[\x00-\x20%\x7F-\xFF]/n
 
-      def self.build_mem_cache(*addresses)
+      # Creates a new Dalli::Client instance with specified addresses and options.
+      # By default address is equal localhost:11211.
+      #
+      #   ActiveSupport::Cache::MemCacheStore.build_mem_cache
+      #     # => #<Dalli::Client:0x007f98a47d2028 @servers=["localhost:11211"], @options={}, @ring=nil>
+      #   ActiveSupport::Cache::MemCacheStore.build_mem_cache('localhost:10290')
+      #     # => #<Dalli::Client:0x007f98a47b3a60 @servers=["localhost:10290"], @options={}, @ring=nil>
+      def self.build_mem_cache(*addresses) # :nodoc:
         addresses = addresses.flatten
         options = addresses.extract_options!
         addresses = ["localhost:11211"] if addresses.empty?
@@ -66,14 +73,17 @@ module ActiveSupport
       def read_multi(*names)
         options = names.extract_options!
         options = merged_options(options)
-        keys_to_names = Hash[names.map{|name| [escape_key(namespaced_key(name, options)), name]}]
-        raw_values = @data.get_multi(keys_to_names.keys, :raw => true)
-        values = {}
-        raw_values.each do |key, value|
-          entry = deserialize_entry(value)
-          values[keys_to_names[key]] = entry.value unless entry.expired?
+
+        instrument_multi(:read, names, options) do
+          keys_to_names = Hash[names.map{|name| [escape_key(namespaced_key(name, options)), name]}]
+          raw_values = @data.get_multi(keys_to_names.keys, :raw => true)
+          values = {}
+          raw_values.each do |key, value|
+            entry = deserialize_entry(value)
+            values[keys_to_names[key]] = entry.value unless entry.expired?
+          end
+          values
         end
-        values
       end
 
       # Increment a cached value. This method uses the memcached incr atomic
diff --git a/activesupport/lib/active_support/cache/memory_store.rb b/activesupport/lib/active_support/cache/memory_store.rb
index 8a0523d0e2..90bb2c38c3 100644
--- a/activesupport/lib/active_support/cache/memory_store.rb
+++ b/activesupport/lib/active_support/cache/memory_store.rb
@@ -126,7 +126,7 @@ module ActiveSupport
 
         PER_ENTRY_OVERHEAD = 240
 
-        def cached_size(key, entry)
+        def cached_size(key, entry) # :nodoc:
           key.to_s.bytesize + entry.size + PER_ENTRY_OVERHEAD
         end
 
diff --git a/activesupport/lib/active_support/cache/strategy/local_cache.rb b/activesupport/lib/active_support/cache/strategy/local_cache.rb
index 73c6b3cb88..fe5bc82c30 100644
--- a/activesupport/lib/active_support/cache/strategy/local_cache.rb
+++ b/activesupport/lib/active_support/cache/strategy/local_cache.rb
@@ -39,7 +39,7 @@ module ActiveSupport
             @data = {}
           end
 
-          # Don't allow synchronizing since it isn't thread safe,
+          # Don't allow synchronizing since it isn't thread safe.
           def synchronize # :nodoc:
             yield
           end
@@ -120,7 +120,7 @@ module ActiveSupport
             super
           end
 
-          def set_cache_value(value, name, amount, options)
+          def set_cache_value(value, name, amount, options) # :nodoc:
             if local_cache
               local_cache.mute do
                 if value
diff --git a/activesupport/lib/active_support/callbacks.rb b/activesupport/lib/active_support/callbacks.rb
index 0f1de8b076..d43fde03a9 100644
--- a/activesupport/lib/active_support/callbacks.rb
+++ b/activesupport/lib/active_support/callbacks.rb
@@ -4,7 +4,9 @@ require 'active_support/core_ext/array/extract_options'
 require 'active_support/core_ext/class/attribute'
 require 'active_support/core_ext/kernel/reporting'
 require 'active_support/core_ext/kernel/singleton_class'
+require 'active_support/core_ext/module/attribute_accessors'
 require 'active_support/core_ext/string/filters'
+require 'active_support/deprecation'
 require 'thread'
 
 module ActiveSupport
@@ -65,6 +67,12 @@ module ActiveSupport
 
     CALLBACK_FILTER_TYPES = [:before, :after, :around]
 
+    # If true, Active Record and Active Model callbacks returning +false+ will
+    # halt the entire callback chain and display a deprecation message.
+    # If false, callback chains will only be halted by calling +throw :abort+.
+    # Defaults to +true+.
+    mattr_accessor(:halt_and_display_warning_on_return_false) { true }
+
     # Runs the callbacks for the given event.
     #
     # Calls the before and around callbacks in the order they were set, yields
@@ -84,9 +92,9 @@ module ActiveSupport
 
     private
 
-    def _run_callbacks(callbacks, &block)
+    def __run_callbacks__(callbacks, &block)
       if callbacks.empty?
-        block.call if block
+        yield if block_given?
       else
         runner = callbacks.compile
         e = Filters::Environment.new(self, false, nil, block)
@@ -125,14 +133,10 @@ module ActiveSupport
         def self.build(callback_sequence, user_callback, user_conditions, chain_config, filter)
           halted_lambda = chain_config[:terminator]
 
-          if chain_config.key?(:terminator) && user_conditions.any?
+          if user_conditions.any?
             halting_and_conditional(callback_sequence, user_callback, user_conditions, halted_lambda, filter)
-          elsif chain_config.key? :terminator
-            halting(callback_sequence, user_callback, halted_lambda, filter)
-          elsif user_conditions.any?
-            conditional(callback_sequence, user_callback, user_conditions)
           else
-            simple callback_sequence, user_callback
+            halting(callback_sequence, user_callback, halted_lambda, filter)
           end
         end
 
@@ -174,42 +178,15 @@ module ActiveSupport
           end
         end
         private_class_method :halting
-
-        def self.conditional(callback_sequence, user_callback, user_conditions)
-          callback_sequence.before do |env|
-            target = env.target
-            value  = env.value
-
-            if user_conditions.all? { |c| c.call(target, value) }
-              user_callback.call target, value
-            end
-
-            env
-          end
-        end
-        private_class_method :conditional
-
-        def self.simple(callback_sequence, user_callback)
-          callback_sequence.before do |env|
-            user_callback.call env.target, env.value
-
-            env
-          end
-        end
-        private_class_method :simple
       end
 
       class After
         def self.build(callback_sequence, user_callback, user_conditions, chain_config)
           if chain_config[:skip_after_callbacks_if_terminated]
-            if chain_config.key?(:terminator) && user_conditions.any?
+            if user_conditions.any?
               halting_and_conditional(callback_sequence, user_callback, user_conditions)
-            elsif chain_config.key?(:terminator)
-              halting(callback_sequence, user_callback)
-            elsif user_conditions.any?
-              conditional callback_sequence, user_callback, user_conditions
             else
-              simple callback_sequence, user_callback
+              halting(callback_sequence, user_callback)
             end
           else
             if user_conditions.any?
@@ -272,14 +249,10 @@ module ActiveSupport
 
       class Around
         def self.build(callback_sequence, user_callback, user_conditions, chain_config)
-          if chain_config.key?(:terminator) && user_conditions.any?
+          if user_conditions.any?
             halting_and_conditional(callback_sequence, user_callback, user_conditions)
-          elsif chain_config.key? :terminator
-            halting(callback_sequence, user_callback)
-          elsif user_conditions.any?
-            conditional(callback_sequence, user_callback, user_conditions)
           else
-            simple(callback_sequence, user_callback)
+            halting(callback_sequence, user_callback)
           end
         end
 
@@ -291,13 +264,11 @@ module ActiveSupport
 
             if !halted && user_conditions.all? { |c| c.call(target, value) }
               user_callback.call(target, value) {
-                env = run.call env
-                env.value
+                run.call.value
               }
-
               env
             else
-              run.call env
+              run.call
             end
           end
         end
@@ -309,46 +280,16 @@ module ActiveSupport
             value  = env.value
 
             if env.halted
-              run.call env
+              run.call
             else
               user_callback.call(target, value) {
-                env = run.call env
-                env.value
+                run.call.value
               }
               env
             end
           end
         end
         private_class_method :halting
-
-        def self.conditional(callback_sequence, user_callback, user_conditions)
-          callback_sequence.around do |env, &run|
-            target = env.target
-            value  = env.value
-
-            if user_conditions.all? { |c| c.call(target, value) }
-              user_callback.call(target, value) {
-                env = run.call env
-                env.value
-              }
-              env
-            else
-              run.call env
-            end
-          end
-        end
-        private_class_method :conditional
-
-        def self.simple(callback_sequence, user_callback)
-          callback_sequence.around do |env, &run|
-            user_callback.call(env.target, env.value) {
-              env = run.call env
-              env.value
-            }
-            env
-          end
-        end
-        private_class_method :simple
       end
     end
 
@@ -373,14 +314,14 @@ module ActiveSupport
       def filter; @key; end
       def raw_filter; @filter; end
 
-      def merge(chain, new_options)
+      def merge_conditional_options(chain, if_option:, unless_option:)
         options = {
           :if     => @if.dup,
           :unless => @unless.dup
         }
 
-        options[:if].concat     Array(new_options.fetch(:unless, []))
-        options[:unless].concat Array(new_options.fetch(:if, []))
+        options[:if].concat     Array(unless_option)
+        options[:unless].concat Array(if_option)
 
         self.class.build chain, @filter, @kind, options
       end
@@ -495,17 +436,17 @@ module ActiveSupport
       end
 
       def around(&around)
-        CallbackSequence.new do |*args|
-          around.call(*args) {
-            self.call(*args)
+        CallbackSequence.new do |arg|
+          around.call(arg) {
+            self.call(arg)
           }
         end
       end
 
-      def call(*args)
-        @before.each { |b| b.call(*args) }
-        value = @call.call(*args)
-        @after.each { |a| a.call(*args) }
+      def call(arg)
+        @before.each { |b| b.call(arg) }
+        value = @call.call(arg)
+        @after.each { |a| a.call(arg) }
         value
       end
     end
@@ -516,12 +457,6 @@ module ActiveSupport
 
       attr_reader :name, :config
 
-      # If true, any callback returning +false+ will halt the entire callback
-      # chain and display a deprecation message. If false, callback chains will
-      # only be halted by calling +throw :abort+. Defaults to +true+.
-      class_attribute :halt_and_display_warning_on_return_false
-      self.halt_and_display_warning_on_return_false = true
-
       def initialize(name, config)
         @name = name
         @config = {
@@ -602,23 +537,12 @@ module ActiveSupport
         Proc.new do |target, result_lambda|
           terminate = true
           catch(:abort) do
-            result = result_lambda.call if result_lambda.is_a?(Proc)
-            if halt_and_display_warning_on_return_false && result == false
-              display_deprecation_warning_for_false_terminator
-            else
-              terminate = false
-            end
+            result_lambda.call if result_lambda.is_a?(Proc)
+            terminate = false
           end
           terminate
         end
       end
-
-      def display_deprecation_warning_for_false_terminator
-        ActiveSupport::Deprecation.warn(<<-MSG.squish)
-          Returning `false` in a callback will not implicitly halt a callback chain in the next release of Rails.
-          To explicitly halt a callback chain, please use `throw :abort` instead.
-        MSG
-      end
     end
 
     module ClassMethods
@@ -644,7 +568,7 @@ module ActiveSupport
       #   set_callback :save, :after,  :after_meth, if: :condition
       #   set_callback :save, :around, ->(r, block) { stuff; result = block.call; stuff }
       #
-      # The second arguments indicates whether the callback is to be run +:before+,
+      # The second argument indicates whether the callback is to be run +:before+,
       # +:after+, or +:around+ the event. If omitted, +:before+ is assumed. This
       # means the first example above can also be written as:
       #
@@ -667,10 +591,12 @@ module ActiveSupport
       #
       # ===== Options
       #
-      # * <tt>:if</tt> - A symbol naming an instance method or a proc; the
-      #   callback will be called only when it returns a +true+ value.
-      # * <tt>:unless</tt> - A symbol naming an instance method or a proc; the
-      #   callback will be called only when it returns a +false+ value.
+      # * <tt>:if</tt> - A symbol, a string or an array of symbols and strings,
+      #   each naming an instance method or a proc; the callback will be called
+      #   only when they all return a true value.
+      # * <tt>:unless</tt> - A symbol, a string or an array of symbols and
+      #   strings, each naming an instance method or a proc; the callback will
+      #   be called only when they all return a false value.
       # * <tt>:prepend</tt> - If +true+, the callback will be prepended to the
       #   existing chain rather than appended.
       def set_callback(name, *filter_list, &block)
@@ -693,19 +619,27 @@ module ActiveSupport
       #   class Writer < Person
       #      skip_callback :validate, :before, :check_membership, if: -> { self.age > 18 }
       #   end
+      #
+      # An <tt>ArgumentError</tt> will be raised if the callback has not
+      # already been set (unless the <tt>:raise</tt> option is set to <tt>false</tt>).
       def skip_callback(name, *filter_list, &block)
         type, filters, options = normalize_callback_params(filter_list, block)
+        options[:raise] = true unless options.key?(:raise)
 
         __update_callbacks(name) do |target, chain|
           filters.each do |filter|
-            filter = chain.find {|c| c.matches?(type, filter) }
+            callback = chain.find {|c| c.matches?(type, filter) }
 
-            if filter && options.any?
-              new_filter = filter.merge(chain, options)
-              chain.insert(chain.index(filter), new_filter)
+            if !callback && options[:raise]
+              raise ArgumentError, "#{type.to_s.capitalize} #{name} callback #{filter.inspect} has not been defined"
             end
 
-            chain.delete(filter)
+            if callback && (options.key?(:if) || options.key?(:unless))
+              new_callback = callback.merge_conditional_options(chain, if_option: options[:if], unless_option: options[:unless])
+              chain.insert(chain.index(callback), new_callback)
+            end
+
+            chain.delete(callback)
           end
           target.set_callbacks name, chain
         end
@@ -735,19 +669,20 @@ module ActiveSupport
       #   callback chain, preventing following before and around callbacks from
       #   being called and the event from being triggered.
       #   This should be a lambda to be executed.
-      #   The current object and the return result of the callback will be called
-      #   with the lambda.
+      #   The current object and the result lambda of the callback will be provided
+      #   to the terminator lambda.
       #
-      #     define_callbacks :validate, terminator: ->(target, result) { result == false }
+      #     define_callbacks :validate, terminator: ->(target, result_lambda) { result_lambda.call == false }
       #
       #   In this example, if any before validate callbacks returns +false+,
       #   any successive before and around callback is not executed.
-      #   Defaults to +false+, meaning no value halts the chain.
+      #
+      #   The default terminator halts the chain when a callback throws +:abort+.
       #
       # * <tt>:skip_after_callbacks_if_terminated</tt> - Determines if after
       #   callbacks should be terminated by the <tt>:terminator</tt> option. By
-      #   default after callbacks executed no matter if callback chain was
-      #   terminated or not. Option makes sense only when <tt>:terminator</tt>
+      #   default after callbacks are executed no matter if callback chain was
+      #   terminated or not. This option makes sense only when <tt>:terminator</tt>
       #   option is specified.
       #
       # * <tt>:scope</tt> - Indicates which methods should be executed when an
@@ -805,7 +740,7 @@ module ActiveSupport
 
           module_eval <<-RUBY, __FILE__, __LINE__ + 1
             def _run_#{name}_callbacks(&block)
-              _run_callbacks(_#{name}_callbacks, &block)
+              __run_callbacks__(_#{name}_callbacks, &block)
             end
           RUBY
         end
@@ -813,13 +748,37 @@ module ActiveSupport
 
       protected
 
-      def get_callbacks(name)
+      def get_callbacks(name) # :nodoc:
         send "_#{name}_callbacks"
       end
 
-      def set_callbacks(name, callbacks)
+      def set_callbacks(name, callbacks) # :nodoc:
         send "_#{name}_callbacks=", callbacks
       end
+
+      def deprecated_false_terminator # :nodoc:
+        Proc.new do |target, result_lambda|
+          terminate = true
+          catch(:abort) do
+            result = result_lambda.call if result_lambda.is_a?(Proc)
+            if Callbacks.halt_and_display_warning_on_return_false && result == false
+              display_deprecation_warning_for_false_terminator
+            else
+              terminate = false
+            end
+          end
+          terminate
+        end
+      end
+
+      private
+
+      def display_deprecation_warning_for_false_terminator
+        ActiveSupport::Deprecation.warn(<<-MSG.squish)
+          Returning `false` in Active Record and Active Model callbacks will not implicitly halt a callback chain in the next release of Rails.
+          To explicitly halt the callback chain, please use `throw :abort` instead.
+        MSG
+      end
     end
   end
 end
diff --git a/activesupport/lib/active_support/concern.rb b/activesupport/lib/active_support/concern.rb
index 342d3a9d52..0403eb70ca 100644
--- a/activesupport/lib/active_support/concern.rb
+++ b/activesupport/lib/active_support/concern.rb
@@ -114,7 +114,7 @@ module ActiveSupport
         return false
       else
         return false if base < self
-        @_dependencies.each { |dep| base.send(:include, dep) }
+        @_dependencies.each { |dep| base.include(dep) }
         super
         base.extend const_get(:ClassMethods) if const_defined?(:ClassMethods)
         base.class_eval(&@_included_block) if instance_variable_defined?(:@_included_block)
@@ -132,7 +132,7 @@ module ActiveSupport
     end
 
     def class_methods(&class_methods_module_definition)
-      mod = const_defined?(:ClassMethods) ?
+      mod = const_defined?(:ClassMethods, false) ?
         const_get(:ClassMethods) :
         const_set(:ClassMethods, Module.new)
 
diff --git a/activesupport/lib/active_support/concurrency/latch.rb b/activesupport/lib/active_support/concurrency/latch.rb
index 1507de433e..7b8df0df04 100644
--- a/activesupport/lib/active_support/concurrency/latch.rb
+++ b/activesupport/lib/active_support/concurrency/latch.rb
@@ -1,26 +1,18 @@
-require 'thread'
-require 'monitor'
+require 'concurrent/atomics'
 
 module ActiveSupport
   module Concurrency
-    class Latch
-      def initialize(count = 1)
-        @count = count
-        @lock = Monitor.new
-        @cv = @lock.new_cond
-      end
+    class Latch < Concurrent::CountDownLatch
 
-      def release
-        @lock.synchronize do
-          @count -= 1 if @count > 0
-          @cv.broadcast if @count.zero?
-        end
+      def initialize(count = 1)
+        ActiveSupport::Deprecation.warn("ActiveSupport::Concurrency::Latch is deprecated. Please use Concurrent::CountDownLatch instead.")
+        super(count)
       end
+      
+      alias_method :release, :count_down
 
       def await
-        @lock.synchronize do
-          @cv.wait_while { @count > 0 }
-        end
+        wait(nil)
       end
     end
   end
diff --git a/activesupport/lib/active_support/concurrency/share_lock.rb b/activesupport/lib/active_support/concurrency/share_lock.rb
new file mode 100644
index 0000000000..ca48164c54
--- /dev/null
+++ b/activesupport/lib/active_support/concurrency/share_lock.rb
@@ -0,0 +1,142 @@
+require 'thread'
+require 'monitor'
+
+module ActiveSupport
+  module Concurrency
+    # A share/exclusive lock, otherwise known as a read/write lock.
+    #
+    # https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock
+    #--
+    # Note that a pending Exclusive lock attempt does not block incoming
+    # Share requests (i.e., we are "read-preferring"). That seems
+    # consistent with the behavior of "loose" upgrades, but may be the
+    # wrong choice otherwise: it nominally reduces the possibility of
+    # deadlock by risking starvation instead.
+    class ShareLock
+      include MonitorMixin
+
+      # We track Thread objects, instead of just using counters, because
+      # we need exclusive locks to be reentrant, and we need to be able
+      # to upgrade share locks to exclusive.
+
+
+      def initialize
+        super()
+
+        @cv = new_cond
+
+        @sharing = Hash.new(0)
+        @waiting = {}
+        @exclusive_thread = nil
+        @exclusive_depth = 0
+      end
+
+      # Returns false if +no_wait+ is set and the lock is not
+      # immediately available. Otherwise, returns true after the lock
+      # has been acquired.
+      #
+      # +purpose+ and +compatible+ work together; while this thread is
+      # waiting for the exclusive lock, it will yield its share (if any)
+      # to any other attempt whose +purpose+ appears in this attempt's
+      # +compatible+ list. This allows a "loose" upgrade, which, being
+      # less strict, prevents some classes of deadlocks.
+      #
+      # For many resources, loose upgrades are sufficient: if a thread
+      # is awaiting a lock, it is not running any other code. With
+      # +purpose+ matching, it is possible to yield only to other
+      # threads whose activity will not interfere.
+      def start_exclusive(purpose: nil, compatible: [], no_wait: false)
+        synchronize do
+          unless @exclusive_thread == Thread.current
+            if busy?(purpose)
+              return false if no_wait
+
+              loose_shares = @sharing.delete(Thread.current)
+              @waiting[Thread.current] = compatible if loose_shares
+
+              begin
+                @cv.wait_while { busy?(purpose) }
+              ensure
+                @waiting.delete Thread.current
+                @sharing[Thread.current] = loose_shares if loose_shares
+              end
+            end
+            @exclusive_thread = Thread.current
+          end
+          @exclusive_depth += 1
+
+          true
+        end
+      end
+
+      # Relinquish the exclusive lock. Must only be called by the thread
+      # that called start_exclusive (and currently holds the lock).
+      def stop_exclusive
+        synchronize do
+          raise "invalid unlock" if @exclusive_thread != Thread.current
+
+          @exclusive_depth -= 1
+          if @exclusive_depth == 0
+            @exclusive_thread = nil
+            @cv.broadcast
+          end
+        end
+      end
+
+      def start_sharing
+        synchronize do
+          if @exclusive_thread && @exclusive_thread != Thread.current
+            @cv.wait_while { @exclusive_thread }
+          end
+          @sharing[Thread.current] += 1
+        end
+      end
+
+      def stop_sharing
+        synchronize do
+          if @sharing[Thread.current] > 1
+            @sharing[Thread.current] -= 1
+          else
+            @sharing.delete Thread.current
+            @cv.broadcast
+          end
+        end
+      end
+
+      # Execute the supplied block while holding the Exclusive lock. If
+      # +no_wait+ is set and the lock is not immediately available,
+      # returns +nil+ without yielding. Otherwise, returns the result of
+      # the block.
+      #
+      # See +start_exclusive+ for other options.
+      def exclusive(purpose: nil, compatible: [], no_wait: false)
+        if start_exclusive(purpose: purpose, compatible: compatible, no_wait: no_wait)
+          begin
+            yield
+          ensure
+            stop_exclusive
+          end
+        end
+      end
+
+      # Execute the supplied block while holding the Share lock.
+      def sharing
+        start_sharing
+        begin
+          yield
+        ensure
+          stop_sharing
+        end
+      end
+
+      private
+
+      # Must be called within synchronize
+      def busy?(purpose)
+        (@exclusive_thread && @exclusive_thread != Thread.current) ||
+          @waiting.any? { |k, v| k != Thread.current && !v.include?(purpose) } ||
+          @sharing.size > (@sharing[Thread.current] > 0 ? 1 : 0)
+      end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/configurable.rb b/activesupport/lib/active_support/configurable.rb
index 3dd44e32d8..8256c325af 100644
--- a/activesupport/lib/active_support/configurable.rb
+++ b/activesupport/lib/active_support/configurable.rb
@@ -122,6 +122,7 @@ module ActiveSupport
           send("#{name}=", yield) if block_given?
         end
       end
+      private :config_accessor
     end
 
     # Reads and writes attributes from a configuration <tt>OrderedHash</tt>.
diff --git a/activesupport/lib/active_support/core_ext/array.rb b/activesupport/lib/active_support/core_ext/array.rb
index 7d0c1e4c8d..7551551bd7 100644
--- a/activesupport/lib/active_support/core_ext/array.rb
+++ b/activesupport/lib/active_support/core_ext/array.rb
@@ -4,3 +4,4 @@ require 'active_support/core_ext/array/conversions'
 require 'active_support/core_ext/array/extract_options'
 require 'active_support/core_ext/array/grouping'
 require 'active_support/core_ext/array/prepend_and_append'
+require 'active_support/core_ext/array/inquiry'
diff --git a/activesupport/lib/active_support/core_ext/array/access.rb b/activesupport/lib/active_support/core_ext/array/access.rb
index 45b89d2705..3177d8498e 100644
--- a/activesupport/lib/active_support/core_ext/array/access.rb
+++ b/activesupport/lib/active_support/core_ext/array/access.rb
@@ -21,12 +21,24 @@ class Array
   #   %w( a b c ).to(-10)  # => []
   def to(position)
     if position >= 0
-      first position + 1
+      take position + 1
     else
       self[0..position]
     end
   end
 
+  # Returns a copy of the Array without the specified elements.
+  #
+  #   people = ["David", "Rafael", "Aaron", "Todd"]
+  #   people.without "Aaron", "Todd"
+  #     => ["David", "Rafael"]
+  #
+  # Note: This is an optimization of `Enumerable#without` that uses `Array#-`
+  # instead of `Array#reject` for performance reasons.
+  def without(*elements)
+    self - elements
+  end
+
   # Equal to <tt>self[1]</tt>.
   #
   #   %w( a b c d e ).second # => "b"
diff --git a/activesupport/lib/active_support/core_ext/array/conversions.rb b/activesupport/lib/active_support/core_ext/array/conversions.rb
index 080e3b5ef7..8718b7e1e5 100644
--- a/activesupport/lib/active_support/core_ext/array/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/array/conversions.rb
@@ -32,7 +32,7 @@ class Array
   #   ['one', 'two', 'three'].to_sentence # => "one, two, and three"
   #
   #   ['one', 'two'].to_sentence(passing: 'invalid option')
-  #   # => ArgumentError: Unknown key :passing
+  #   # => ArgumentError: Unknown key: :passing. Valid keys are: :words_connector, :two_words_connector, :last_word_connector, :locale
   #
   #   ['one', 'two'].to_sentence(two_words_connector: '-')
   #   # => "one-two"
@@ -74,7 +74,7 @@ class Array
     when 0
       ''
     when 1
-      self[0].to_s.dup
+      "#{self[0]}"
     when 2
       "#{self[0]}#{options[:two_words_connector]}#{self[1]}"
     else
@@ -85,7 +85,9 @@ class Array
   # Extends <tt>Array#to_s</tt> to convert a collection of elements into a
   # comma separated id list if <tt>:db</tt> argument is given as the format.
   #
-  #   Blog.all.to_formatted_s(:db) # => "1,2,3"
+  #   Blog.all.to_formatted_s(:db)  # => "1,2,3"
+  #   Blog.none.to_formatted_s(:db) # => "null"
+  #   [1,2].to_formatted_s          # => "[1, 2]"
   def to_formatted_s(format = :default)
     case format
     when :db
diff --git a/activesupport/lib/active_support/core_ext/array/inquiry.rb b/activesupport/lib/active_support/core_ext/array/inquiry.rb
new file mode 100644
index 0000000000..e8f44cc378
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/array/inquiry.rb
@@ -0,0 +1,17 @@
+require 'active_support/array_inquirer'
+
+class Array
+  # Wraps the array in an +ArrayInquirer+ object, which gives a friendlier way
+  # to check its string-like contents.
+  #
+  #   pets = [:cat, :dog].inquiry
+  #
+  #   pets.cat?     # => true
+  #   pets.ferret?  # => false
+  #
+  #   pets.any?(:cat, :ferret)  # => true
+  #   pets.any?(:ferret, :alligator)  # => false
+  def inquiry
+    ActiveSupport::ArrayInquirer.new(self)
+  end
+end
diff --git a/activesupport/lib/active_support/core_ext/array/wrap.rb b/activesupport/lib/active_support/core_ext/array/wrap.rb
index 152eb02218..b611d34c27 100644
--- a/activesupport/lib/active_support/core_ext/array/wrap.rb
+++ b/activesupport/lib/active_support/core_ext/array/wrap.rb
@@ -3,7 +3,7 @@ class Array
   #
   # Specifically:
   #
-  # * If the argument is +nil+ an empty list is returned.
+  # * If the argument is +nil+ an empty array is returned.
   # * Otherwise, if the argument responds to +to_ary+ it is invoked, and its result returned.
   # * Otherwise, returns an array with the argument as its single element.
   #
@@ -15,12 +15,13 @@ class Array
   #
   # * If the argument responds to +to_ary+ the method is invoked. <tt>Kernel#Array</tt>
   #   moves on to try +to_a+ if the returned value is +nil+, but <tt>Array.wrap</tt> returns
-  #   +nil+ right away.
+  #   an array with the argument as its single element right away.
   # * If the returned value from +to_ary+ is neither +nil+ nor an +Array+ object, <tt>Kernel#Array</tt>
   #   raises an exception, while <tt>Array.wrap</tt> does not, it just returns the value.
-  # * It does not call +to_a+ on the argument, but returns an empty array if argument is +nil+.
+  # * It does not call +to_a+ on the argument, if the argument does not respond to +to_ary+
+  #   it returns an array with the argument as its single element.
   #
-  # The second point is easily explained with some enumerables:
+  # The last point is easily explained with some enumerables:
   #
   #   Array(foo: :bar)      # => [[:foo, :bar]]
   #   Array.wrap(foo: :bar) # => [{:foo=>:bar}]
diff --git a/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb b/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
index 234283e792..22fc7ecf92 100644
--- a/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
@@ -1,15 +1,14 @@
 require 'bigdecimal'
 require 'bigdecimal/util'
 
-class BigDecimal
-  DEFAULT_STRING_FORMAT = 'F'
-  alias_method :to_default_s, :to_s
+module ActiveSupport
+  module BigDecimalWithDefaultFormat #:nodoc:
+    DEFAULT_STRING_FORMAT = 'F'
 
-  def to_s(format = nil, options = nil)
-    if format.is_a?(Symbol)
-      to_formatted_s(format, options || {})
-    else
-      to_default_s(format || DEFAULT_STRING_FORMAT)
+    def to_s(format = nil)
+      super(format || DEFAULT_STRING_FORMAT)
     end
   end
 end
+
+BigDecimal.prepend(ActiveSupport::BigDecimalWithDefaultFormat)
diff --git a/activesupport/lib/active_support/core_ext/class.rb b/activesupport/lib/active_support/core_ext/class.rb
index c750a10bb2..ef903d59b5 100644
--- a/activesupport/lib/active_support/core_ext/class.rb
+++ b/activesupport/lib/active_support/core_ext/class.rb
@@ -1,3 +1,2 @@
 require 'active_support/core_ext/class/attribute'
-require 'active_support/core_ext/class/delegating_attributes'
 require 'active_support/core_ext/class/subclasses'
diff --git a/activesupport/lib/active_support/core_ext/class/attribute.rb b/activesupport/lib/active_support/core_ext/class/attribute.rb
index f2b7bb3ef1..802d988af2 100644
--- a/activesupport/lib/active_support/core_ext/class/attribute.rb
+++ b/activesupport/lib/active_support/core_ext/class/attribute.rb
@@ -75,11 +75,15 @@ class Class
     instance_predicate = options.fetch(:instance_predicate, true)
 
     attrs.each do |name|
+      remove_possible_singleton_method(name)
       define_singleton_method(name) { nil }
+
+      remove_possible_singleton_method("#{name}?")
       define_singleton_method("#{name}?") { !!public_send(name) } if instance_predicate
 
       ivar = "@#{name}"
 
+      remove_possible_singleton_method("#{name}=")
       define_singleton_method("#{name}=") do |val|
         singleton_class.class_eval do
           remove_possible_method(name)
@@ -110,10 +114,15 @@ class Class
             self.class.public_send name
           end
         end
+
+        remove_possible_method "#{name}?"
         define_method("#{name}?") { !!public_send(name) } if instance_predicate
       end
 
-      attr_writer name if instance_writer
+      if instance_writer
+        remove_possible_method "#{name}="
+        attr_writer name
+      end
     end
   end
 end
diff --git a/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb b/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
deleted file mode 100644
index 1c305c5970..0000000000
--- a/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
+++ /dev/null
@@ -1,45 +0,0 @@
-require 'active_support/core_ext/kernel/singleton_class'
-require 'active_support/core_ext/module/remove_method'
-require 'active_support/core_ext/module/deprecation'
-
-
-class Class
-  def superclass_delegating_accessor(name, options = {})
-    # Create private _name and _name= methods that can still be used if the public
-    # methods are overridden.
-    _superclass_delegating_accessor("_#{name}", options)
-
-    # Generate the public methods name, name=, and name?.
-    # These methods dispatch to the private _name, and _name= methods, making them
-    # overridable.
-    singleton_class.send(:define_method, name) { send("_#{name}") }
-    singleton_class.send(:define_method, "#{name}?") { !!send("_#{name}") }
-    singleton_class.send(:define_method, "#{name}=") { |value| send("_#{name}=", value) }
-
-    # If an instance_reader is needed, generate public instance methods name and name?.
-    if options[:instance_reader] != false
-      define_method(name) { send("_#{name}") }
-      define_method("#{name}?") { !!send("#{name}") }
-    end
-  end
-
-  deprecate superclass_delegating_accessor: :class_attribute
-
-  private
-    # Take the object being set and store it in a method. This gives us automatic
-    # inheritance behavior, without having to store the object in an instance
-    # variable and look up the superclass chain manually.
-    def _stash_object_in_method(object, method, instance_reader = true)
-      singleton_class.remove_possible_method(method)
-      singleton_class.send(:define_method, method) { object }
-      remove_possible_method(method)
-      define_method(method) { object } if instance_reader
-    end
-
-    def _superclass_delegating_accessor(name, options = {})
-      singleton_class.send(:define_method, "#{name}=") do |value|
-        _stash_object_in_method(value, name, options[:instance_reader] != false)
-      end
-      send("#{name}=", nil)
-    end
-end
diff --git a/activesupport/lib/active_support/core_ext/date.rb b/activesupport/lib/active_support/core_ext/date.rb
index 465fedda80..7f0f4639a2 100644
--- a/activesupport/lib/active_support/core_ext/date.rb
+++ b/activesupport/lib/active_support/core_ext/date.rb
@@ -1,5 +1,5 @@
 require 'active_support/core_ext/date/acts_like'
+require 'active_support/core_ext/date/blank'
 require 'active_support/core_ext/date/calculations'
 require 'active_support/core_ext/date/conversions'
 require 'active_support/core_ext/date/zones'
-
diff --git a/activesupport/lib/active_support/core_ext/date/blank.rb b/activesupport/lib/active_support/core_ext/date/blank.rb
new file mode 100644
index 0000000000..71627b6a6f
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/date/blank.rb
@@ -0,0 +1,12 @@
+require 'date'
+
+class Date #:nodoc:
+  # No Date is blank:
+  #
+  #   Date.today.blank? # => false
+  #
+  # @return [false]
+  def blank?
+    false
+  end
+end
diff --git a/activesupport/lib/active_support/core_ext/date/calculations.rb b/activesupport/lib/active_support/core_ext/date/calculations.rb
index c60e833441..d589b67bf7 100644
--- a/activesupport/lib/active_support/core_ext/date/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date/calculations.rb
@@ -26,7 +26,7 @@ class Date
       Thread.current[:beginning_of_week] = find_beginning_of_week!(week_start)
     end
 
-    # Returns week start day symbol (e.g. :monday), or raises an ArgumentError for invalid day symbol.
+    # Returns week start day symbol (e.g. :monday), or raises an +ArgumentError+ for invalid day symbol.
     def find_beginning_of_week!(week_start)
       raise ArgumentError, "Invalid beginning of week: #{week_start}" unless ::Date::DAYS_INTO_WEEK.key?(week_start)
       week_start
diff --git a/activesupport/lib/active_support/core_ext/date/conversions.rb b/activesupport/lib/active_support/core_ext/date/conversions.rb
index df419a6e63..ed8bca77ac 100644
--- a/activesupport/lib/active_support/core_ext/date/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/date/conversions.rb
@@ -35,6 +35,7 @@ class Date
   #   date.to_s(:db)                      # => "2007-11-10"
   #
   #   date.to_formatted_s(:short)         # => "10 Nov"
+  #   date.to_formatted_s(:number)        # => "20071110"
   #   date.to_formatted_s(:long)          # => "November 10, 2007"
   #   date.to_formatted_s(:long_ordinal)  # => "November 10th, 2007"
   #   date.to_formatted_s(:rfc822)        # => "10 Nov 2007"
@@ -74,14 +75,19 @@ class Date
   #
   #   date = Date.new(2007, 11, 10)  # => Sat, 10 Nov 2007
   #
-  #   date.to_time                   # => Sat Nov 10 00:00:00 0800 2007
-  #   date.to_time(:local)           # => Sat Nov 10 00:00:00 0800 2007
+  #   date.to_time                   # => 2007-11-10 00:00:00 0800
+  #   date.to_time(:local)           # => 2007-11-10 00:00:00 0800
   #
-  #   date.to_time(:utc)             # => Sat Nov 10 00:00:00 UTC 2007
+  #   date.to_time(:utc)             # => 2007-11-10 00:00:00 UTC
   def to_time(form = :local)
     ::Time.send(form, year, month, day)
   end
 
+  # Returns a string which represents the time in used time zone as DateTime
+  # defined by XML Schema:
+  #
+  #   date = Date.new(2015, 05, 23)  # => Sat, 23 May 2015
+  #   date.xmlschema                 # => "2015-05-23T00:00:00+04:00"
   def xmlschema
     in_time_zone.xmlschema
   end
diff --git a/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
index 9525c10112..e079af594d 100644
--- a/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
@@ -92,15 +92,28 @@ module DateAndTime
     end
 
     # Returns a new date/time at the start of the month.
-    # DateTime objects will have a time set to 0:00.
+    #
+    #   today = Date.today # => Thu, 18 Jun 2015
+    #   today.beginning_of_month # => Mon, 01 Jun 2015
+    #
+    # +DateTime+ objects will have a time set to 0:00.
+    #
+    #   now = DateTime.current # => Thu, 18 Jun 2015 15:23:13 +0000
+    #   now.beginning_of_month # => Mon, 01 Jun 2015 00:00:00 +0000
     def beginning_of_month
       first_hour(change(:day => 1))
     end
     alias :at_beginning_of_month :beginning_of_month
 
     # Returns a new date/time at the start of the quarter.
-    # Example: 1st January, 1st July, 1st October.
-    # DateTime objects will have a time set to 0:00.
+    #
+    #   today = Date.today # => Fri, 10 Jul 2015
+    #   today.beginning_of_quarter # => Wed, 01 Jul 2015
+    #
+    # +DateTime+ objects will have a time set to 0:00.
+    #
+    #   now = DateTime.current # => Fri, 10 Jul 2015 18:41:29 +0000
+    #   now.beginning_of_quarter # => Wed, 01 Jul 2015 00:00:00 +0000
     def beginning_of_quarter
       first_quarter_month = [10, 7, 4, 1].detect { |m| m <= month }
       beginning_of_month.change(:month => first_quarter_month)
@@ -108,26 +121,50 @@ module DateAndTime
     alias :at_beginning_of_quarter :beginning_of_quarter
 
     # Returns a new date/time at the end of the quarter.
-    # Example: 31st March, 30th June, 30th September.
-    # DateTime objects will have a time set to 23:59:59.
+    #
+    #   today = Date.today # => Fri, 10 Jul 2015
+    #   today.end_of_quarter # => Wed, 30 Sep 2015
+    #
+    # +DateTime+ objects will have a time set to 23:59:59.
+    #
+    #   now = DateTime.current # => Fri, 10 Jul 2015 18:41:29 +0000
+    #   now.end_of_quarter # => Wed, 30 Sep 2015 23:59:59 +0000
     def end_of_quarter
       last_quarter_month = [3, 6, 9, 12].detect { |m| m >= month }
       beginning_of_month.change(:month => last_quarter_month).end_of_month
     end
     alias :at_end_of_quarter :end_of_quarter
 
-    # Return a new date/time at the beginning of the year.
-    # Example: 1st January.
-    # DateTime objects will have a time set to 0:00.
+    # Returns a new date/time at the beginning of the year.
+    #
+    #   today = Date.today # => Fri, 10 Jul 2015
+    #   today.beginning_of_year # => Thu, 01 Jan 2015
+    #
+    # +DateTime+ objects will have a time set to 0:00.
+    #
+    #   now = DateTime.current # => Fri, 10 Jul 2015 18:41:29 +0000
+    #   now.beginning_of_year # => Thu, 01 Jan 2015 00:00:00 +0000
     def beginning_of_year
       change(:month => 1).beginning_of_month
     end
     alias :at_beginning_of_year :beginning_of_year
 
     # Returns a new date/time representing the given day in the next week.
+    #
+    #   today = Date.today # => Thu, 07 May 2015
+    #   today.next_week    # => Mon, 11 May 2015
+    #
     # The +given_day_in_next_week+ defaults to the beginning of the week
     # which is determined by +Date.beginning_of_week+ or +config.beginning_of_week+
-    # when set. +DateTime+ objects have their time set to 0:00 unless +same_time+ is true.
+    # when set.
+    #
+    #   today = Date.today       # => Thu, 07 May 2015
+    #   today.next_week(:friday) # => Fri, 15 May 2015
+    #
+    # +DateTime+ objects have their time set to 0:00 unless +same_time+ is true.
+    #
+    #   now = DateTime.current # => Thu, 07 May 2015 13:31:16 +0000
+    #   now.next_week      # => Mon, 11 May 2015 00:00:00 +0000
     def next_week(given_day_in_next_week = Date.beginning_of_week, same_time: false)
       result = first_hour(weeks_since(1).beginning_of_week.days_since(days_span(given_day_in_next_week)))
       same_time ? copy_time_to(result) : result
diff --git a/activesupport/lib/active_support/core_ext/date_and_time/zones.rb b/activesupport/lib/active_support/core_ext/date_and_time/zones.rb
index 96c6df9407..d29a8db5cf 100644
--- a/activesupport/lib/active_support/core_ext/date_and_time/zones.rb
+++ b/activesupport/lib/active_support/core_ext/date_and_time/zones.rb
@@ -4,7 +4,7 @@ module DateAndTime
     # if Time.zone_default is set. Otherwise, it returns the current time.
     #
     #   Time.zone = 'Hawaii'        # => 'Hawaii'
-    #   DateTime.utc(2000).in_time_zone # => Fri, 31 Dec 1999 14:00:00 HST -10:00
+    #   Time.utc(2000).in_time_zone # => Fri, 31 Dec 1999 14:00:00 HST -10:00
     #   Date.new(2000).in_time_zone  # => Sat, 01 Jan 2000 00:00:00 HST -10:00
     #
     # This method is similar to Time#localtime, except that it uses <tt>Time.zone</tt> as the local zone
@@ -14,7 +14,6 @@ module DateAndTime
     # and the conversion will be based on that zone instead of <tt>Time.zone</tt>.
     #
     #   Time.utc(2000).in_time_zone('Alaska') # => Fri, 31 Dec 1999 15:00:00 AKST -09:00
-    #   DateTime.utc(2000).in_time_zone('Alaska') # => Fri, 31 Dec 1999 15:00:00 AKST -09:00
     #   Date.new(2000).in_time_zone('Alaska')  # => Sat, 01 Jan 2000 00:00:00 AKST -09:00
     def in_time_zone(zone = ::Time.zone)
       time_zone = ::Time.find_zone! zone
diff --git a/activesupport/lib/active_support/core_ext/date_time.rb b/activesupport/lib/active_support/core_ext/date_time.rb
index e8a27b9f38..bcb228b09a 100644
--- a/activesupport/lib/active_support/core_ext/date_time.rb
+++ b/activesupport/lib/active_support/core_ext/date_time.rb
@@ -1,4 +1,5 @@
 require 'active_support/core_ext/date_time/acts_like'
+require 'active_support/core_ext/date_time/blank'
 require 'active_support/core_ext/date_time/calculations'
 require 'active_support/core_ext/date_time/conversions'
 require 'active_support/core_ext/date_time/zones'
diff --git a/activesupport/lib/active_support/core_ext/date_time/blank.rb b/activesupport/lib/active_support/core_ext/date_time/blank.rb
new file mode 100644
index 0000000000..56981b75fb
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/date_time/blank.rb
@@ -0,0 +1,12 @@
+require 'date'
+
+class DateTime #:nodoc:
+  # No DateTime is ever blank:
+  #
+  #   DateTime.now.blank? # => false
+  #
+  # @return [false]
+  def blank?
+    false
+  end
+end
diff --git a/activesupport/lib/active_support/core_ext/date_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
index 55ad384f4f..95617fb8c2 100644
--- a/activesupport/lib/active_support/core_ext/date_time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
@@ -168,7 +168,7 @@ class DateTime
     if other.kind_of?(Infinity)
       super
     elsif other.respond_to? :to_datetime
-      super other.to_datetime
+      super other.to_datetime rescue nil
     else
       nil
     end
diff --git a/activesupport/lib/active_support/core_ext/date_time/conversions.rb b/activesupport/lib/active_support/core_ext/date_time/conversions.rb
index 2a9c09fc29..f59d05b214 100644
--- a/activesupport/lib/active_support/core_ext/date_time/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/conversions.rb
@@ -40,6 +40,8 @@ class DateTime
   alias_method :to_default_s, :to_s if instance_methods(false).include?(:to_s)
   alias_method :to_s, :to_formatted_s
 
+  # Returns a formatted string of the offset from UTC, or an alternative
+  # string if the time zone is already UTC.
   #
   #   datetime = DateTime.civil(2000, 1, 1, 0, 0, 0, Rational(-6, 24))
   #   datetime.formatted_offset         # => "-06:00"
diff --git a/activesupport/lib/active_support/core_ext/enumerable.rb b/activesupport/lib/active_support/core_ext/enumerable.rb
index 1343beb87a..fc7531d088 100644
--- a/activesupport/lib/active_support/core_ext/enumerable.rb
+++ b/activesupport/lib/active_support/core_ext/enumerable.rb
@@ -60,6 +60,32 @@ module Enumerable
   def exclude?(object)
     !include?(object)
   end
+
+  # Returns a copy of the enumerable without the specified elements.
+  #
+  #   ["David", "Rafael", "Aaron", "Todd"].without "Aaron", "Todd"
+  #     => ["David", "Rafael"]
+  #
+  #   {foo: 1, bar: 2, baz: 3}.without :bar
+  #     => {foo: 1, baz: 3}
+  def without(*elements)
+    reject { |element| elements.include?(element) }
+  end
+
+  # Convert an enumerable to an array based on the given key.
+  #
+  #   [{ name: "David" }, { name: "Rafael" }, { name: "Aaron" }].pluck(:name)
+  #     => ["David", "Rafael", "Aaron"]
+  #
+  #   [{ id: 1, name: "David" }, { id: 2, name: "Rafael" }].pluck(:id, :name)
+  #     => [[1, "David"], [2, "Rafael"]]
+  def pluck(*keys)
+    if keys.many?
+      map { |element| keys.map { |key| element[key] } }
+    else
+      map { |element| element[keys.first] }
+    end
+  end
 end
 
 class Range #:nodoc:
diff --git a/activesupport/lib/active_support/core_ext/file/atomic.rb b/activesupport/lib/active_support/core_ext/file/atomic.rb
index 38374af388..463fd78412 100644
--- a/activesupport/lib/active_support/core_ext/file/atomic.rb
+++ b/activesupport/lib/active_support/core_ext/file/atomic.rb
@@ -8,40 +8,45 @@ class File
   #     file.write('hello')
   #   end
   #
-  # If your temp directory is not on the same filesystem as the file you're
-  # trying to write, you can provide a different temporary directory.
+  # This method needs to create a temporary file. By default it will create it
+  # in the same directory as the destination file. If you don't like this
+  # behavior you can provide a different directory but it must be on the
+  # same physical filesystem as the file you're trying to write.
   #
   #   File.atomic_write('/data/something.important', '/data/tmp') do |file|
   #     file.write('hello')
   #   end
-  def self.atomic_write(file_name, temp_dir = Dir.tmpdir)
+  def self.atomic_write(file_name, temp_dir = dirname(file_name))
     require 'tempfile' unless defined?(Tempfile)
-    require 'fileutils' unless defined?(FileUtils)
 
-    temp_file = Tempfile.new(basename(file_name), temp_dir)
-    temp_file.binmode
-    yield temp_file
-    temp_file.close
+    Tempfile.open(".#{basename(file_name)}", temp_dir) do |temp_file|
+      temp_file.binmode
+      return_val = yield temp_file
+      temp_file.close
 
-    if File.exist?(file_name)
-      # Get original file permissions
-      old_stat = stat(file_name)
-    else
-      # If not possible, probe which are the default permissions in the
-      # destination directory.
-      old_stat = probe_stat_in(dirname(file_name))
-    end
+      old_stat = if exist?(file_name)
+        # Get original file permissions
+        stat(file_name)
+      elsif temp_dir != dirname(file_name)
+        # If not possible, probe which are the default permissions in the
+        # destination directory.
+        probe_stat_in(dirname(file_name))
+      end
 
-    # Overwrite original file with temp file
-    FileUtils.mv(temp_file.path, file_name)
+      if old_stat
+        # Set correct permissions on new file
+        begin
+          chown(old_stat.uid, old_stat.gid, temp_file.path)
+          # This operation will affect filesystem ACL's
+          chmod(old_stat.mode, temp_file.path)
+        rescue Errno::EPERM, Errno::EACCES
+          # Changing file ownership failed, moving on.
+        end
+      end
 
-    # Set correct permissions on new file
-    begin
-      chown(old_stat.uid, old_stat.gid, file_name)
-      # This operation will affect filesystem ACL's
-      chmod(old_stat.mode, file_name)
-    rescue Errno::EPERM, Errno::EACCES
-      # Changing file ownership failed, moving on.
+      # Overwrite original file with temp file
+      rename(temp_file.path, file_name)
+      return_val
     end
   end
 
diff --git a/activesupport/lib/active_support/core_ext/hash/conversions.rb b/activesupport/lib/active_support/core_ext/hash/conversions.rb
index 2149d4439d..8594d9bf2e 100644
--- a/activesupport/lib/active_support/core_ext/hash/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/hash/conversions.rb
@@ -106,7 +106,25 @@ class Hash
     #   # => {"hash"=>{"foo"=>1, "bar"=>2}}
     #
     # +DisallowedType+ is raised if the XML contains attributes with <tt>type="yaml"</tt> or
-    # <tt>type="symbol"</tt>. Use <tt>Hash.from_trusted_xml</tt> to parse this XML.
+    # <tt>type="symbol"</tt>. Use <tt>Hash.from_trusted_xml</tt> to
+    # parse this XML.
+    #
+    # Custom +disallowed_types+ can also be passed in the form of an
+    # array.
+    #
+    #   xml = <<-XML
+    #     <?xml version="1.0" encoding="UTF-8"?>
+    #       <hash>
+    #         <foo type="integer">1</foo>
+    #         <bar type="string">"David"</bar>
+    #       </hash>
+    #   XML
+    #
+    #   hash = Hash.from_xml(xml, ['integer'])
+    #   # => ActiveSupport::XMLConverter::DisallowedType: Disallowed type attribute: "integer"
+    #
+    # Note that passing custom disallowed types will override the default types,
+    # which are Symbol and YAML.
     def from_xml(xml, disallowed_types = nil)
       ActiveSupport::XMLConverter.new(xml, disallowed_types).to_h
     end
diff --git a/activesupport/lib/active_support/core_ext/hash/except.rb b/activesupport/lib/active_support/core_ext/hash/except.rb
index 6e397abf51..2f6d38c1f6 100644
--- a/activesupport/lib/active_support/core_ext/hash/except.rb
+++ b/activesupport/lib/active_support/core_ext/hash/except.rb
@@ -1,8 +1,9 @@
 class Hash
-  # Returns a hash that includes everything but the given keys.
-  #   hash = { a: true, b: false, c: nil}
-  #   hash.except(:c) # => { a: true, b: false}
-  #   hash # => { a: true, b: false, c: nil}
+  # Returns a hash that includes everything except given keys.
+  #   hash = { a: true, b: false, c: nil }
+  #   hash.except(:c)     # => { a: true, b: false }
+  #   hash.except(:a, :b) # => { c: nil }
+  #   hash                # => { a: true, b: false, c: nil }
   #
   # This is useful for limiting a set of parameters to everything but a few known toggles:
   #   @person.update(params[:person].except(:admin))
@@ -10,10 +11,10 @@ class Hash
     dup.except!(*keys)
   end
 
-  # Replaces the hash without the given keys.
-  #   hash = { a: true, b: false, c: nil}
-  #   hash.except!(:c) # => { a: true, b: false}
-  #   hash # => { a: true, b: false }
+  # Removes the given keys from hash and returns it.
+  #   hash = { a: true, b: false, c: nil }
+  #   hash.except!(:c) # => { a: true, b: false }
+  #   hash             # => { a: true, b: false }
   def except!(*keys)
     keys.each { |key| delete(key) }
     self
diff --git a/activesupport/lib/active_support/core_ext/hash/keys.rb b/activesupport/lib/active_support/core_ext/hash/keys.rb
index 9297a59c46..07a282e8b6 100644
--- a/activesupport/lib/active_support/core_ext/hash/keys.rb
+++ b/activesupport/lib/active_support/core_ext/hash/keys.rb
@@ -1,10 +1,14 @@
 class Hash
-  # Returns a new hash with all keys converted using the block operation.
+  # Returns a new hash with all keys converted using the +block+ operation.
   #
   #  hash = { name: 'Rob', age: '28' }
   #
-  #  hash.transform_keys{ |key| key.to_s.upcase }
-  #  # => {"NAME"=>"Rob", "AGE"=>"28"}
+  #  hash.transform_keys { |key| key.to_s.upcase } # => {"NAME"=>"Rob", "AGE"=>"28"}
+  #
+  # If you do not provide a +block+, it will return an Enumerator
+  # for chaining with other methods:
+  #
+  #  hash.transform_keys.with_index { |k, i| [k, i].join } # => {"name0"=>"Rob", "age1"=>"28"}
   def transform_keys
     return enum_for(:transform_keys) unless block_given?
     result = self.class.new
@@ -14,8 +18,8 @@ class Hash
     result
   end
 
-  # Destructively convert all keys using the block operations.
-  # Same as transform_keys but modifies +self+.
+  # Destructively converts all keys using the +block+ operations.
+  # Same as +transform_keys+ but modifies +self+.
   def transform_keys!
     return enum_for(:transform_keys!) unless block_given?
     keys.each do |key|
@@ -34,7 +38,7 @@ class Hash
     transform_keys(&:to_s)
   end
 
-  # Destructively convert all keys to strings. Same as
+  # Destructively converts all keys to strings. Same as
   # +stringify_keys+, but modifies +self+.
   def stringify_keys!
     transform_keys!(&:to_s)
@@ -52,15 +56,15 @@ class Hash
   end
   alias_method :to_options,  :symbolize_keys
 
-  # Destructively convert all keys to symbols, as long as they respond
+  # Destructively converts all keys to symbols, as long as they respond
   # to +to_sym+. Same as +symbolize_keys+, but modifies +self+.
   def symbolize_keys!
     transform_keys!{ |key| key.to_sym rescue key }
   end
   alias_method :to_options!, :symbolize_keys!
 
-  # Validate all keys in a hash match <tt>*valid_keys</tt>, raising
-  # ArgumentError on a mismatch.
+  # Validates all keys in a hash match <tt>*valid_keys</tt>, raising
+  # +ArgumentError+ on a mismatch.
   #
   # Note that keys are treated differently than HashWithIndifferentAccess,
   # meaning that string and symbol keys will not match.
@@ -89,7 +93,7 @@ class Hash
     _deep_transform_keys_in_object(self, &block)
   end
 
-  # Destructively convert all keys by using the block operation.
+  # Destructively converts all keys by using the block operation.
   # This includes the keys from the root hash and from all
   # nested hashes and arrays.
   def deep_transform_keys!(&block)
@@ -108,7 +112,7 @@ class Hash
     deep_transform_keys(&:to_s)
   end
 
-  # Destructively convert all keys to strings.
+  # Destructively converts all keys to strings.
   # This includes the keys from the root hash and from all
   # nested hashes and arrays.
   def deep_stringify_keys!
@@ -127,7 +131,7 @@ class Hash
     deep_transform_keys{ |key| key.to_sym rescue key }
   end
 
-  # Destructively convert all keys to symbols, as long as they respond
+  # Destructively converts all keys to symbols, as long as they respond
   # to +to_sym+. This includes the keys from the root hash and from all
   # nested hashes and arrays.
   def deep_symbolize_keys!
diff --git a/activesupport/lib/active_support/core_ext/hash/slice.rb b/activesupport/lib/active_support/core_ext/hash/slice.rb
index 41b2279013..1d5f38231a 100644
--- a/activesupport/lib/active_support/core_ext/hash/slice.rb
+++ b/activesupport/lib/active_support/core_ext/hash/slice.rb
@@ -1,5 +1,5 @@
 class Hash
-  # Slice a hash to include only the given keys. Returns a hash containing 
+  # Slices a hash to include only the given keys. Returns a hash containing 
   # the given keys.
   # 
   #   { a: 1, b: 2, c: 3, d: 4 }.slice(:a, :b)
diff --git a/activesupport/lib/active_support/core_ext/hash/transform_values.rb b/activesupport/lib/active_support/core_ext/hash/transform_values.rb
index e9bcce761f..9ddb838774 100644
--- a/activesupport/lib/active_support/core_ext/hash/transform_values.rb
+++ b/activesupport/lib/active_support/core_ext/hash/transform_values.rb
@@ -2,10 +2,15 @@ class Hash
   # Returns a new hash with the results of running +block+ once for every value.
   # The keys are unchanged.
   #
-  #   { a: 1, b: 2, c: 3 }.transform_values { |x| x * 2 }
-  #   # => { a: 2, b: 4, c: 6 }
+  #   { a: 1, b: 2, c: 3 }.transform_values { |x| x * 2 } # => { a: 2, b: 4, c: 6 }
+  #
+  # If you do not provide a +block+, it will return an Enumerator
+  # for chaining with other methods:
+  #
+  #   { a: 1, b: 2 }.transform_values.with_index { |v, i| [v, i].join.to_i } # => { a: 10, b: 21 }
   def transform_values
     return enum_for(:transform_values) unless block_given?
+    return {} if empty?
     result = self.class.new
     each do |key, value|
       result[key] = yield(value)
@@ -13,7 +18,8 @@ class Hash
     result
   end
 
-  # Destructive +transform_values+
+  # Destructively converts all values using the +block+ operations.
+  # Same as +transform_values+ but modifies +self+.
   def transform_values!
     return enum_for(:transform_values!) unless block_given?
     each do |key, value|
diff --git a/activesupport/lib/active_support/core_ext/integer/time.rb b/activesupport/lib/active_support/core_ext/integer/time.rb
index 82080ffe51..87185b024f 100644
--- a/activesupport/lib/active_support/core_ext/integer/time.rb
+++ b/activesupport/lib/active_support/core_ext/integer/time.rb
@@ -17,28 +17,13 @@ class Integer
   #
   #   # equivalent to Time.now.advance(months: 4, years: 5)
   #   (4.months + 5.years).from_now
-  #
-  # While these methods provide precise calculation when used as in the examples
-  # above, care should be taken to note that this is not true if the result of
-  # +months+, +years+, etc is converted before use:
-  #
-  #   # equivalent to 30.days.to_i.from_now
-  #   1.month.to_i.from_now
-  #
-  #   # equivalent to 365.25.days.to_f.from_now
-  #   1.year.to_f.from_now
-  #
-  # In such cases, Ruby's core
-  # Date[http://ruby-doc.org/stdlib/libdoc/date/rdoc/Date.html] and
-  # Time[http://ruby-doc.org/stdlib/libdoc/time/rdoc/Time.html] should be used for precision
-  # date and time arithmetic.
   def months
     ActiveSupport::Duration.new(self * 30.days, [[:months, self]])
   end
   alias :month :months
 
   def years
-    ActiveSupport::Duration.new(self * 365.25.days, [[:years, self]])
+    ActiveSupport::Duration.new(self * 365.25.days.to_i, [[:years, self]])
   end
   alias :year :years
 end
diff --git a/activesupport/lib/active_support/core_ext/kernel/reporting.rb b/activesupport/lib/active_support/core_ext/kernel/reporting.rb
index 9189e6d977..8afc258df8 100644
--- a/activesupport/lib/active_support/core_ext/kernel/reporting.rb
+++ b/activesupport/lib/active_support/core_ext/kernel/reporting.rb
@@ -1,5 +1,3 @@
-require 'tempfile'
-
 module Kernel
   # Sets $VERBOSE to nil for the duration of the block and back to its original
   # value afterwards.
diff --git a/activesupport/lib/active_support/core_ext/load_error.rb b/activesupport/lib/active_support/core_ext/load_error.rb
index d9fb392752..60732eb41a 100644
--- a/activesupport/lib/active_support/core_ext/load_error.rb
+++ b/activesupport/lib/active_support/core_ext/load_error.rb
@@ -23,7 +23,7 @@ class LoadError
   # Returns true if the given path name (except perhaps for the ".rb"
   # extension) is the missing file which caused the exception to be raised.
   def is_missing?(location)
-    location.sub(/\.rb$/, '') == path.sub(/\.rb$/, '')
+    location.sub(/\.rb$/, ''.freeze) == path.sub(/\.rb$/, ''.freeze)
   end
 end
 
diff --git a/activesupport/lib/active_support/core_ext/marshal.rb b/activesupport/lib/active_support/core_ext/marshal.rb
index 56c79c04bd..e333b26133 100644
--- a/activesupport/lib/active_support/core_ext/marshal.rb
+++ b/activesupport/lib/active_support/core_ext/marshal.rb
@@ -1,21 +1,19 @@
-require 'active_support/core_ext/module/aliasing'
-
-module Marshal
-  class << self
-    def load_with_autoloading(source)
-      load_without_autoloading(source)
+module ActiveSupport
+  module MarshalWithAutoloading # :nodoc:
+    def load(source)
+      super(source)
     rescue ArgumentError, NameError => exc
       if exc.message.match(%r|undefined class/module (.+)|)
         # try loading the class/module
         $1.constantize
-        # if it is a IO we need to go back to read the object
+        # if it is an IO we need to go back to read the object
         source.rewind if source.respond_to?(:rewind)
         retry
       else
         raise exc
       end
     end
-
-    alias_method_chain :load, :autoloading
   end
 end
+
+Marshal.singleton_class.prepend(ActiveSupport::MarshalWithAutoloading)
diff --git a/activesupport/lib/active_support/core_ext/module/aliasing.rb b/activesupport/lib/active_support/core_ext/module/aliasing.rb
index 0a6fadf928..b6934b9c54 100644
--- a/activesupport/lib/active_support/core_ext/module/aliasing.rb
+++ b/activesupport/lib/active_support/core_ext/module/aliasing.rb
@@ -1,4 +1,7 @@
 class Module
+  # NOTE: This method is deprecated. Please use <tt>Module#prepend</tt> that
+  # comes with Ruby 2.0 or newer instead.
+  #
   # Encapsulates the common pattern of:
   #
   #   alias_method :foo_without_feature, :foo
@@ -21,6 +24,8 @@ class Module
   #
   # so you can safely chain foo, foo?, foo! and/or foo= with the same feature.
   def alias_method_chain(target, feature)
+    ActiveSupport::Deprecation.warn("alias_method_chain is deprecated. Please, use Module#prepend instead. From module, you can access the original method using super.")
+
     # Strip out punctuation on predicates, bang or writer methods since
     # e.g. target?_without_feature is not a valid method name.
     aliased_target, punctuation = target.to_s.sub(/([?!=])$/, ''), $1
@@ -43,7 +48,7 @@ class Module
   end
 
   # Allows you to make aliases for attributes, which includes
-  # getter, setter, and query methods.
+  # getter, setter, and a predicate.
   #
   #   class Content < ActiveRecord::Base
   #     # has a title attribute
diff --git a/activesupport/lib/active_support/core_ext/module/anonymous.rb b/activesupport/lib/active_support/core_ext/module/anonymous.rb
index b0c7b021db..510c9a5430 100644
--- a/activesupport/lib/active_support/core_ext/module/anonymous.rb
+++ b/activesupport/lib/active_support/core_ext/module/anonymous.rb
@@ -7,12 +7,21 @@ class Module
   #   m = Module.new
   #   m.name # => nil
   #
+  # +anonymous?+ method returns true if module does not have a name, false otherwise:
+  #
+  #   Module.new.anonymous? # => true
+  #
+  #   module M; end
+  #   M.anonymous?          # => false
+  #
   # A module gets a name when it is first assigned to a constant. Either
   # via the +module+ or +class+ keyword or by an explicit assignment:
   #
   #   m = Module.new # creates an anonymous module
-  #   M = m          # => m gets a name here as a side-effect
+  #   m.anonymous?   # => true
+  #   M = m          # m gets a name here as a side-effect
   #   m.name         # => "M"
+  #   m.anonymous?   # => false
   def anonymous?
     name.nil?
   end
diff --git a/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb b/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb
index d4e6b5a1ac..bf175a8a70 100644
--- a/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb
+++ b/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb
@@ -19,9 +19,9 @@ class Module
   # The attribute name must be a valid method name in Ruby.
   #
   #   module Foo
-  #     mattr_reader :"1_Badname "
+  #     mattr_reader :"1_Badname"
   #   end
-  #   # => NameError: invalid attribute name
+  #   # => NameError: invalid attribute name: 1_Badname
   #
   # If you want to opt out the creation on the instance reader method, pass
   # <tt>instance_reader: false</tt> or <tt>instance_accessor: false</tt>.
@@ -53,7 +53,7 @@ class Module
   def mattr_reader(*syms)
     options = syms.extract_options!
     syms.each do |sym|
-      raise NameError.new("invalid attribute name: #{sym}") unless sym =~ /^[_A-Za-z]\w*$/
+      raise NameError.new("invalid attribute name: #{sym}") unless sym =~ /\A[_A-Za-z]\w*\z/
       class_eval(<<-EOS, __FILE__, __LINE__ + 1)
         @@#{sym} = nil unless defined? @@#{sym}
 
@@ -119,7 +119,7 @@ class Module
   def mattr_writer(*syms)
     options = syms.extract_options!
     syms.each do |sym|
-      raise NameError.new("invalid attribute name: #{sym}") unless sym =~ /^[_A-Za-z]\w*$/
+      raise NameError.new("invalid attribute name: #{sym}") unless sym =~ /\A[_A-Za-z]\w*\z/
       class_eval(<<-EOS, __FILE__, __LINE__ + 1)
         @@#{sym} = nil unless defined? @@#{sym}
 
@@ -206,7 +206,7 @@ class Module
   #   Person.class_variable_get("@@hair_colors") # => [:brown, :black, :blonde, :red]
   def mattr_accessor(*syms, &blk)
     mattr_reader(*syms, &blk)
-    mattr_writer(*syms, &blk)
+    mattr_writer(*syms)
   end
   alias :cattr_accessor :mattr_accessor
 end
diff --git a/activesupport/lib/active_support/core_ext/module/concerning.rb b/activesupport/lib/active_support/core_ext/module/concerning.rb
index 07a392404e..65b88b9bbd 100644
--- a/activesupport/lib/active_support/core_ext/module/concerning.rb
+++ b/activesupport/lib/active_support/core_ext/module/concerning.rb
@@ -63,10 +63,10 @@ class Module
   #
   # == Mix-in noise exiled to its own file:
   #
-  # Once our chunk of behavior starts pushing the scroll-to-understand it's
+  # Once our chunk of behavior starts pushing the scroll-to-understand-it
   # boundary, we give in and move it to a separate file. At this size, the
-  # overhead feels in good proportion to the size of our extraction, despite
-  # diluting our at-a-glance sense of how things really work.
+  # increased overhead can be a reasonable tradeoff even if it reduces our
+  # at-a-glance perception of how things work.
   #
   #   class Todo
   #     # Other todo implementation
@@ -99,7 +99,7 @@ class Module
   #   end
   #
   #   Todo.ancestors
-  #   # => Todo, Todo::EventTracking, Object
+  #   # => [Todo, Todo::EventTracking, Object]
   #
   # This small step has some wonderful ripple effects. We can
   # * grok the behavior of our class in one glance,
diff --git a/activesupport/lib/active_support/core_ext/module/delegation.rb b/activesupport/lib/active_support/core_ext/module/delegation.rb
index 24df83800b..0d46248582 100644
--- a/activesupport/lib/active_support/core_ext/module/delegation.rb
+++ b/activesupport/lib/active_support/core_ext/module/delegation.rb
@@ -5,10 +5,11 @@ class Module
   # option is not used.
   class DelegationError < NoMethodError; end
 
-  RUBY_RESERVED_WORDS = Set.new(
-    %w(alias and BEGIN begin break case class def defined? do else elsif END
-       end ensure false for if in module next nil not or redo rescue retry
-       return self super then true undef unless until when while yield)
+  DELEGATION_RESERVED_METHOD_NAMES = Set.new(
+    %w(_ arg args alias and BEGIN begin block break case class def defined? do
+       else elsif END end ensure false for if in module next nil not or redo
+       rescue retry return self super then true undef unless until when while
+       yield)
   ).freeze
 
   # Provides a +delegate+ class method to easily expose contained objects'
@@ -167,11 +168,11 @@ class Module
         ''
       end
 
-    file, line = caller.first.split(':', 2)
+    file, line = caller(1, 1).first.split(':'.freeze, 2)
     line = line.to_i
 
     to = to.to_s
-    to = "self.#{to}" if RUBY_RESERVED_WORDS.include?(to)
+    to = "self.#{to}" if DELEGATION_RESERVED_METHOD_NAMES.include?(to)
 
     methods.each do |method|
       # Attribute writer methods only accept one argument. Makes sure []=
@@ -185,19 +186,31 @@ class Module
       # On the other hand it could be that the target has side-effects,
       # whereas conceptually, from the user point of view, the delegator should
       # be doing one call.
-
-      exception = %(raise DelegationError, "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}")
-
-      method_def = [
-        "def #{method_prefix}#{method}(#{definition})",
-        "  _ = #{to}",
-        "  if !_.nil? || nil.respond_to?(:#{method})",
-        "    _.#{method}(#{definition})",
-        "  else",
-        "    #{exception unless allow_nil}",
-        "  end",
+      if allow_nil
+        method_def = [
+          "def #{method_prefix}#{method}(#{definition})",
+          "_ = #{to}",
+          "if !_.nil? || nil.respond_to?(:#{method})",
+          "  _.#{method}(#{definition})",
+          "end",
         "end"
-      ].join ';'
+        ].join ';'
+      else
+        exception = %(raise DelegationError, "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}")
+
+        method_def = [
+          "def #{method_prefix}#{method}(#{definition})",
+          " _ = #{to}",
+          "  _.#{method}(#{definition})",
+          "rescue NoMethodError => e",
+          "  if _.nil? && e.name == :#{method}",
+          "    #{exception}",
+          "  else",
+          "    raise",
+          "  end",
+          "end"
+        ].join ';'
+      end
 
       module_eval(method_def, file, line)
     end
diff --git a/activesupport/lib/active_support/core_ext/module/remove_method.rb b/activesupport/lib/active_support/core_ext/module/remove_method.rb
index 8a2569a7d0..d5ec16d68a 100644
--- a/activesupport/lib/active_support/core_ext/module/remove_method.rb
+++ b/activesupport/lib/active_support/core_ext/module/remove_method.rb
@@ -1,15 +1,35 @@
 class Module
-  # Remove the named method, if it exists.
+  # Removes the named method, if it exists.
   def remove_possible_method(method)
     if method_defined?(method) || private_method_defined?(method)
       undef_method(method)
     end
   end
 
-  # Replace the existing method definition, if there is one, with the contents
-  # of the block.
+  # Removes the named singleton method, if it exists.
+  def remove_possible_singleton_method(method)
+    singleton_class.instance_eval do
+      remove_possible_method(method)
+    end
+  end
+
+  # Replaces the existing method definition, if there is one, with the passed
+  # block as its body.
   def redefine_method(method, &block)
+    visibility = method_visibility(method)
     remove_possible_method(method)
     define_method(method, &block)
+    send(visibility, method)
+  end
+
+  def method_visibility(method) # :nodoc:
+    case
+    when private_method_defined?(method)
+      :private
+    when protected_method_defined?(method)
+      :protected
+    else
+      :public
+    end
   end
 end
diff --git a/activesupport/lib/active_support/core_ext/name_error.rb b/activesupport/lib/active_support/core_ext/name_error.rb
index b82148e4e5..6b447d772b 100644
--- a/activesupport/lib/active_support/core_ext/name_error.rb
+++ b/activesupport/lib/active_support/core_ext/name_error.rb
@@ -23,8 +23,7 @@ class NameError
   #   # => true
   def missing_name?(name)
     if name.is_a? Symbol
-      last_name = (missing_name || '').split('::').last
-      last_name == name.to_s
+      self.name == name
     else
       missing_name == name.to_s
     end
diff --git a/activesupport/lib/active_support/core_ext/numeric.rb b/activesupport/lib/active_support/core_ext/numeric.rb
index a6bc0624be..bcdc3eace2 100644
--- a/activesupport/lib/active_support/core_ext/numeric.rb
+++ b/activesupport/lib/active_support/core_ext/numeric.rb
@@ -1,3 +1,4 @@
 require 'active_support/core_ext/numeric/bytes'
 require 'active_support/core_ext/numeric/time'
+require 'active_support/core_ext/numeric/inquiry'
 require 'active_support/core_ext/numeric/conversions'
diff --git a/activesupport/lib/active_support/core_ext/numeric/conversions.rb b/activesupport/lib/active_support/core_ext/numeric/conversions.rb
index 0c8ff79237..9a3651f29a 100644
--- a/activesupport/lib/active_support/core_ext/numeric/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/numeric/conversions.rb
@@ -1,7 +1,7 @@
 require 'active_support/core_ext/big_decimal/conversions'
 require 'active_support/number_helper'
 
-class Numeric
+module ActiveSupport::NumericWithFormat
 
   # Provides options for converting numbers into formatted strings.
   # Options are provided for phone numbers, currency, percentage,
@@ -41,7 +41,7 @@ class Numeric
   #  1000.to_s(:percentage, delimiter: '.', separator: ',') # => 1.000,000%
   #  302.24398923423.to_s(:percentage, precision: 5)        # => 302.24399%
   #  1000.to_s(:percentage, locale: :fr)                    # => 1 000,000%
-  #  100.to_s(:percentage, format: '%n  %')                 # => 100  %
+  #  100.to_s(:percentage, format: '%n  %')                 # => 100.000  %
   #
   #  Delimited:
   #  12345678.to_s(:delimited)                     # => 12,345,678
@@ -78,7 +78,7 @@ class Numeric
   #  1234567.to_s(:human_size, precision: 2)                 # => 1.2 MB
   #  483989.to_s(:human_size, precision: 2)                  # => 470 KB
   #  1234567.to_s(:human_size, precision: 2, separator: ',') # => 1,2 MB
-  #  1234567890123.to_s(:human_size, precision: 5)           # => "1.1229 TB"
+  #  1234567890123.to_s(:human_size, precision: 5)           # => "1.1228 TB"
   #  524288000.to_s(:human_size, precision: 5)               # => "500 MB"
   #
   #  Human-friendly format:
@@ -97,7 +97,10 @@ class Numeric
   #  1234567.to_s(:human, precision: 1,
   #                   separator: ',',
   #                   significant: false)                   # => "1,2 Million"
-  def to_formatted_s(format = :default, options = {})
+  def to_s(*args)
+    format, options = args
+    options ||= {}
+
     case format
     when :phone
       return ActiveSupport::NumberHelper.number_to_phone(self, options)
@@ -114,32 +117,16 @@ class Numeric
     when :human_size
       return ActiveSupport::NumberHelper.number_to_human_size(self, options)
     else
-      self.to_default_s
-    end
-  end
-
-  [Fixnum, Bignum].each do |klass|
-    klass.class_eval do
-      alias_method :to_default_s, :to_s
-      def to_s(base_or_format = 10, options = nil)
-        if base_or_format.is_a?(Symbol)
-          to_formatted_s(base_or_format, options || {})
-        else
-          to_default_s(base_or_format)
-        end
-      end
+      super
     end
   end
 
-  Float.class_eval do
-    alias_method :to_default_s, :to_s
-    def to_s(*args)
-      if args.empty?
-        to_default_s
-      else
-        to_formatted_s(*args)
-      end
-    end
+  def to_formatted_s(*args)
+    to_s(*args)
   end
+  deprecate to_formatted_s: :to_s
+end
 
+[Fixnum, Bignum, Float, BigDecimal].each do |klass|
+  klass.prepend(ActiveSupport::NumericWithFormat)
 end
diff --git a/activesupport/lib/active_support/core_ext/numeric/inquiry.rb b/activesupport/lib/active_support/core_ext/numeric/inquiry.rb
new file mode 100644
index 0000000000..7e7ac1b0b2
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/numeric/inquiry.rb
@@ -0,0 +1,26 @@
+unless 1.respond_to?(:positive?) # TODO: Remove this file when we drop support to ruby < 2.3
+class Numeric
+  # Returns true if the number is positive.
+  #
+  #   1.positive?  # => true
+  #   0.positive?  # => false
+  #   -1.positive? # => false
+  def positive?
+    self > 0
+  end
+
+  # Returns true if the number is negative.
+  #
+  #   -1.negative? # => true
+  #   0.negative?  # => false
+  #   1.negative?  # => false
+  def negative?
+    self < 0
+  end
+end
+
+class Complex
+  undef :positive?
+  undef :negative?
+end
+end
diff --git a/activesupport/lib/active_support/core_ext/numeric/time.rb b/activesupport/lib/active_support/core_ext/numeric/time.rb
index ef32817f55..6c4a975495 100644
--- a/activesupport/lib/active_support/core_ext/numeric/time.rb
+++ b/activesupport/lib/active_support/core_ext/numeric/time.rb
@@ -1,6 +1,8 @@
 require 'active_support/duration'
 require 'active_support/core_ext/time/calculations'
 require 'active_support/core_ext/time/acts_like'
+require 'active_support/core_ext/date/calculations'
+require 'active_support/core_ext/date/acts_like'
 
 class Numeric
   # Enables the use of time calculations and declarations, like 45.minutes + 2.hours + 4.years.
@@ -16,21 +18,6 @@ class Numeric
   #
   #   # equivalent to Time.current.advance(months: 4, years: 5)
   #   (4.months + 5.years).from_now
-  #
-  # While these methods provide precise calculation when used as in the examples above, care
-  # should be taken to note that this is not true if the result of `months', `years', etc is
-  # converted before use:
-  #
-  #   # equivalent to 30.days.to_i.from_now
-  #   1.month.to_i.from_now
-  #
-  #   # equivalent to 365.25.days.to_f.from_now
-  #   1.year.to_f.from_now
-  #
-  # In such cases, Ruby's core
-  # Date[http://ruby-doc.org/stdlib/libdoc/date/rdoc/Date.html] and
-  # Time[http://ruby-doc.org/stdlib/libdoc/time/rdoc/Time.html] should be used for precision
-  # date and time arithmetic.
   def seconds
     ActiveSupport::Duration.new(self, [[:seconds, self]])
   end
diff --git a/activesupport/lib/active_support/core_ext/object/blank.rb b/activesupport/lib/active_support/core_ext/object/blank.rb
index 38e43478df..039c50a4a2 100644
--- a/activesupport/lib/active_support/core_ext/object/blank.rb
+++ b/activesupport/lib/active_support/core_ext/object/blank.rb
@@ -1,12 +1,10 @@
-# encoding: utf-8
-
 class Object
   # An object is blank if it's false, empty, or a whitespace string.
-  # For example, '', '   ', +nil+, [], and {} are all blank.
+  # For example, +false+, '', '   ', +nil+, [], and {} are all blank.
   #
   # This simplifies
   #
-  #   address.nil? || address.empty?
+  #   !address || address.empty?
   #
   # to
   #
@@ -129,3 +127,14 @@ class Numeric #:nodoc:
     false
   end
 end
+
+class Time #:nodoc:
+  # No Time is blank:
+  #
+  #   Time.now.blank? # => false
+  #
+  # @return [false]
+  def blank?
+    false
+  end
+end
diff --git a/activesupport/lib/active_support/core_ext/object/deep_dup.rb b/activesupport/lib/active_support/core_ext/object/deep_dup.rb
index 0191d2e973..8dfeed0066 100644
--- a/activesupport/lib/active_support/core_ext/object/deep_dup.rb
+++ b/activesupport/lib/active_support/core_ext/object/deep_dup.rb
@@ -39,8 +39,15 @@ class Hash
   #   hash[:a][:c] # => nil
   #   dup[:a][:c]  # => "c"
   def deep_dup
-    each_with_object(dup) do |(key, value), hash|
-      hash[key.deep_dup] = value.deep_dup
+    hash = dup
+    each_pair do |key, value|
+      if key.frozen? && ::String === key
+        hash[key] = value.deep_dup
+      else
+        hash.delete(key)
+        hash[key.deep_dup] = value.deep_dup
+      end
     end
+    hash
   end
 end
diff --git a/activesupport/lib/active_support/core_ext/object/duplicable.rb b/activesupport/lib/active_support/core_ext/object/duplicable.rb
index 620f7b6561..befa5aee21 100644
--- a/activesupport/lib/active_support/core_ext/object/duplicable.rb
+++ b/activesupport/lib/active_support/core_ext/object/duplicable.rb
@@ -19,7 +19,7 @@
 class Object
   # Can you safely dup this object?
   #
-  # False for +nil+, +false+, +true+, symbol, number objects;
+  # False for +nil+, +false+, +true+, symbol, number, method objects;
   # true otherwise.
   def duplicable?
     true
@@ -78,6 +78,10 @@ end
 
 require 'bigdecimal'
 class BigDecimal
+  # BigDecimals are duplicable:
+  #
+  # BigDecimal.new("1.2").duplicable? # => true
+  # BigDecimal.new("1.2").dup         # => #<BigDecimal:...,'0.12E1',18(18)>
   def duplicable?
     true
   end
diff --git a/activesupport/lib/active_support/core_ext/object/inclusion.rb b/activesupport/lib/active_support/core_ext/object/inclusion.rb
index 55f281b213..d4c17dfb07 100644
--- a/activesupport/lib/active_support/core_ext/object/inclusion.rb
+++ b/activesupport/lib/active_support/core_ext/object/inclusion.rb
@@ -5,7 +5,7 @@ class Object
   #   characters = ["Konata", "Kagami", "Tsukasa"]
   #   "Konata".in?(characters) # => true
   #
-  # This will throw an ArgumentError if the argument doesn't respond
+  # This will throw an +ArgumentError+ if the argument doesn't respond
   # to +#include?+.
   def in?(another_object)
     another_object.include?(self)
@@ -18,7 +18,7 @@ class Object
   #
   #   params[:bucket_type].presence_in %w( project calendar )
   #
-  # This will throw an ArgumentError if the argument doesn't respond to +#include?+.
+  # This will throw an +ArgumentError+ if the argument doesn't respond to +#include?+.
   #
   # @return [Object]
   def presence_in(another_object)
diff --git a/activesupport/lib/active_support/core_ext/object/json.rb b/activesupport/lib/active_support/core_ext/object/json.rb
index 698b2d1920..0db787010c 100644
--- a/activesupport/lib/active_support/core_ext/object/json.rb
+++ b/activesupport/lib/active_support/core_ext/object/json.rb
@@ -9,7 +9,6 @@ require 'time'
 require 'active_support/core_ext/time/conversions'
 require 'active_support/core_ext/date_time/conversions'
 require 'active_support/core_ext/date/conversions'
-require 'active_support/core_ext/module/aliasing'
 
 # The JSON gem adds a few modules to Ruby core classes containing :to_json definition, overwriting
 # their default behavior. That said, we need to define the basic to_json method in all of them,
@@ -26,22 +25,25 @@ require 'active_support/core_ext/module/aliasing'
 # bypassed completely. This means that as_json won't be invoked and the JSON gem will simply
 # ignore any options it does not natively understand. This also means that ::JSON.{generate,dump}
 # should give exactly the same results with or without active support.
-[Object, Array, FalseClass, Float, Hash, Integer, NilClass, String, TrueClass, Enumerable].each do |klass|
-  klass.class_eval do
-    def to_json_with_active_support_encoder(options = nil)
+
+module ActiveSupport
+  module ToJsonWithActiveSupportEncoder # :nodoc:
+    def to_json(options = nil)
       if options.is_a?(::JSON::State)
         # Called from JSON.{generate,dump}, forward it to JSON gem's to_json
-        self.to_json_without_active_support_encoder(options)
+        super(options)
       else
         # to_json is being invoked directly, use ActiveSupport's encoder
         ActiveSupport::JSON.encode(self, options)
       end
     end
-
-    alias_method_chain :to_json, :active_support_encoder
   end
 end
 
+[Object, Array, FalseClass, Float, Hash, Integer, NilClass, String, TrueClass, Enumerable].reverse_each do |klass|
+  klass.prepend(ActiveSupport::ToJsonWithActiveSupportEncoder)
+end
+
 class Object
   def as_json(options = nil) #:nodoc:
     if respond_to?(:to_hash)
diff --git a/activesupport/lib/active_support/core_ext/object/try.rb b/activesupport/lib/active_support/core_ext/object/try.rb
index e0f70b9caa..8c16d95b62 100644
--- a/activesupport/lib/active_support/core_ext/object/try.rb
+++ b/activesupport/lib/active_support/core_ext/object/try.rb
@@ -1,4 +1,34 @@
+require 'delegate'
+
+module ActiveSupport
+  module Tryable #:nodoc:
+    def try(*a, &b)
+      try!(*a, &b) if a.empty? || respond_to?(a.first)
+    end
+
+    def try!(*a, &b)
+      if a.empty? && block_given?
+        if b.arity == 0
+          instance_eval(&b)
+        else
+          yield self
+        end
+      else
+        public_send(*a, &b)
+      end
+    end
+  end
+end
+
 class Object
+  include ActiveSupport::Tryable
+
+  ##
+  # :method: try
+  #
+  # :call-seq:
+  #   try(*a, &b)
+  #
   # Invokes the public method whose name goes as first argument just like
   # +public_send+ does, except that if the receiver does not respond to it the
   # call returns +nil+ rather than raising an exception.
@@ -56,30 +86,40 @@ class Object
   #
   # Please also note that +try+ is defined on +Object+. Therefore, it won't work
   # with instances of classes that do not have +Object+ among their ancestors,
-  # like direct subclasses of +BasicObject+. For example, using +try+ with
-  # +SimpleDelegator+ will delegate +try+ to the target instead of calling it on
-  # the delegator itself.
-  def try(*a, &b)
-    try!(*a, &b) if a.empty? || respond_to?(a.first)
-  end
+  # like direct subclasses of +BasicObject+.
 
-  # Same as #try, but raises a NoMethodError exception if the receiver is
+  ##
+  # :method: try!
+  #
+  # :call-seq:
+  #   try!(*a, &b)
+  #
+  # Same as #try, but raises a +NoMethodError+ exception if the receiver is
   # not +nil+ and does not implement the tried method.
   #
   #   "a".try!(:upcase) # => "A"
   #   nil.try!(:upcase) # => nil
   #   123.try!(:upcase) # => NoMethodError: undefined method `upcase' for 123:Fixnum
-  def try!(*a, &b)
-    if a.empty? && block_given?
-      if b.arity.zero?
-        instance_eval(&b)
-      else
-        yield self
-      end
-    else
-      public_send(*a, &b)
-    end
-  end
+end
+
+class Delegator
+  include ActiveSupport::Tryable
+
+  ##
+  # :method: try
+  #
+  # :call-seq:
+  #   try(a*, &b)
+  #
+  # See Object#try
+
+  ##
+  # :method: try!
+  #
+  # :call-seq:
+  #   try!(a*, &b)
+  #
+  # See Object#try!
 end
 
 class NilClass
diff --git a/activesupport/lib/active_support/core_ext/object/with_options.rb b/activesupport/lib/active_support/core_ext/object/with_options.rb
index 7d38e1d134..513c8b1d55 100644
--- a/activesupport/lib/active_support/core_ext/object/with_options.rb
+++ b/activesupport/lib/active_support/core_ext/object/with_options.rb
@@ -7,7 +7,7 @@ class Object
   # provided. Each method called on the block variable must take an options
   # hash as its final argument.
   #
-  # Without <tt>with_options></tt>, this code contains duplication:
+  # Without <tt>with_options</tt>, this code contains duplication:
   #
   #   class Account < ActiveRecord::Base
   #     has_many :customers, dependent: :destroy
diff --git a/activesupport/lib/active_support/core_ext/range/conversions.rb b/activesupport/lib/active_support/core_ext/range/conversions.rb
index b1a12781f3..83eced50bf 100644
--- a/activesupport/lib/active_support/core_ext/range/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/range/conversions.rb
@@ -3,9 +3,24 @@ class Range
     :db => Proc.new { |start, stop| "BETWEEN '#{start.to_s(:db)}' AND '#{stop.to_s(:db)}'" }
   }
 
-  # Gives a human readable format of the range.
+  # Convert range to a formatted string. See RANGE_FORMATS for predefined formats.
   #
-  #   (1..100).to_formatted_s # => "1..100"
+  # This method is aliased to <tt>to_s</tt>.
+  #
+  #   range = (1..100)           # => 1..100
+  #
+  #   range.to_formatted_s       # => "1..100"
+  #   range.to_s                 # => "1..100"
+  #
+  #   range.to_formatted_s(:db)  # => "BETWEEN '1' AND '100'"
+  #   range.to_s(:db)            # => "BETWEEN '1' AND '100'"
+  #
+  # == Adding your own range formats to to_formatted_s
+  # You can add your own formats to the Range::RANGE_FORMATS hash.
+  # Use the format name as the hash key and a Proc instance.
+  #
+  #   # config/initializers/range_formats.rb
+  #   Range::RANGE_FORMATS[:short] = ->(start, stop) { "Between #{start.to_s(:db)} and #{stop.to_s(:db)}" }
   def to_formatted_s(format = :default)
     if formatter = RANGE_FORMATS[format]
       formatter.call(first, last)
diff --git a/activesupport/lib/active_support/core_ext/range/each.rb b/activesupport/lib/active_support/core_ext/range/each.rb
index ecef78f55f..dc6dad5ced 100644
--- a/activesupport/lib/active_support/core_ext/range/each.rb
+++ b/activesupport/lib/active_support/core_ext/range/each.rb
@@ -1,23 +1,21 @@
-require 'active_support/core_ext/module/aliasing'
+module ActiveSupport
+  module EachTimeWithZone #:nodoc:
+    def each(&block)
+      ensure_iteration_allowed
+      super
+    end
 
-class Range #:nodoc:
+    def step(n = 1, &block)
+      ensure_iteration_allowed
+      super
+    end
 
-  def each_with_time_with_zone(&block)
-    ensure_iteration_allowed
-    each_without_time_with_zone(&block)
-  end
-  alias_method_chain :each, :time_with_zone
+    private
 
-  def step_with_time_with_zone(n = 1, &block)
-    ensure_iteration_allowed
-    step_without_time_with_zone(n, &block)
-  end
-  alias_method_chain :step, :time_with_zone
-
-  private
-  def ensure_iteration_allowed
-    if first.is_a?(Time)
-      raise TypeError, "can't iterate from #{first.class}"
-    end
+      def ensure_iteration_allowed
+        raise TypeError, "can't iterate from #{first.class}" if first.is_a?(Time)
+      end
   end
 end
+
+Range.prepend(ActiveSupport::EachTimeWithZone)
diff --git a/activesupport/lib/active_support/core_ext/range/include_range.rb b/activesupport/lib/active_support/core_ext/range/include_range.rb
index 3a07401c8a..c69e1e3fb9 100644
--- a/activesupport/lib/active_support/core_ext/range/include_range.rb
+++ b/activesupport/lib/active_support/core_ext/range/include_range.rb
@@ -1,23 +1,23 @@
-require 'active_support/core_ext/module/aliasing'
-
-class Range
-  # Extends the default Range#include? to support range comparisons.
-  #  (1..5).include?(1..5) # => true
-  #  (1..5).include?(2..3) # => true
-  #  (1..5).include?(2..6) # => false
-  #
-  # The native Range#include? behavior is untouched.
-  #  ('a'..'f').include?('c') # => true
-  #  (5..9).include?(11) # => false
-  def include_with_range?(value)
-    if value.is_a?(::Range)
-      # 1...10 includes 1..9 but it does not include 1..10.
-      operator = exclude_end? && !value.exclude_end? ? :< : :<=
-      include_without_range?(value.first) && value.last.send(operator, last)
-    else
-      include_without_range?(value)
+module ActiveSupport
+  module IncludeWithRange #:nodoc:
+    # Extends the default Range#include? to support range comparisons.
+    #  (1..5).include?(1..5) # => true
+    #  (1..5).include?(2..3) # => true
+    #  (1..5).include?(2..6) # => false
+    #
+    # The native Range#include? behavior is untouched.
+    #  ('a'..'f').include?('c') # => true
+    #  (5..9).include?(11) # => false
+    def include?(value)
+      if value.is_a?(::Range)
+        # 1...10 includes 1..9 but it does not include 1..10.
+        operator = exclude_end? && !value.exclude_end? ? :< : :<=
+        super(value.first) && value.last.send(operator, last)
+      else
+        super
+      end
     end
   end
-
-  alias_method_chain :include?, :range
 end
+
+Range.prepend(ActiveSupport::IncludeWithRange)
diff --git a/activesupport/lib/active_support/core_ext/securerandom.rb b/activesupport/lib/active_support/core_ext/securerandom.rb
index 6cdbea1f37..98cf7430f7 100644
--- a/activesupport/lib/active_support/core_ext/securerandom.rb
+++ b/activesupport/lib/active_support/core_ext/securerandom.rb
@@ -10,8 +10,8 @@ module SecureRandom
   #
   # The result may contain alphanumeric characters except 0, O, I and l
   #
-  #   p SecureRandom.base58 #=> "4kUgL2pdQMSCQtjE"
-  #   p SecureRandom.base58(24) #=> "77TMHrHJFvFDwodq8w7Ev2m7"
+  #   p SecureRandom.base58 # => "4kUgL2pdQMSCQtjE"
+  #   p SecureRandom.base58(24) # => "77TMHrHJFvFDwodq8w7Ev2m7"
   #
   def self.base58(n = 16)
     SecureRandom.random_bytes(n).unpack("C*").map do |byte|
diff --git a/activesupport/lib/active_support/core_ext/string/behavior.rb b/activesupport/lib/active_support/core_ext/string/behavior.rb
index 4aa960039b..710f1f4670 100644
--- a/activesupport/lib/active_support/core_ext/string/behavior.rb
+++ b/activesupport/lib/active_support/core_ext/string/behavior.rb
@@ -1,5 +1,5 @@
 class String
-  # Enable more predictable duck-typing on String-like classes. See <tt>Object#acts_like?</tt>.
+  # Enables more predictable duck-typing on String-like classes. See <tt>Object#acts_like?</tt>.
   def acts_like_string?
     true
   end
diff --git a/activesupport/lib/active_support/core_ext/string/conversions.rb b/activesupport/lib/active_support/core_ext/string/conversions.rb
index 3e0cb8a7ac..fd79a40e31 100644
--- a/activesupport/lib/active_support/core_ext/string/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/string/conversions.rb
@@ -14,7 +14,7 @@ class String
   #   "06:12".to_time                    # => 2012-12-13 06:12:00 +0100
   #   "2012-12-13 06:12".to_time         # => 2012-12-13 06:12:00 +0100
   #   "2012-12-13T06:12".to_time         # => 2012-12-13 06:12:00 +0100
-  #   "2012-12-13T06:12".to_time(:utc)   # => 2012-12-13 05:12:00 UTC
+  #   "2012-12-13T06:12".to_time(:utc)   # => 2012-12-13 06:12:00 UTC
   #   "12/13/2012".to_time               # => ArgumentError: argument out of range
   def to_time(form = :local)
     parts = Date._parse(self, false)
diff --git a/activesupport/lib/active_support/core_ext/string/filters.rb b/activesupport/lib/active_support/core_ext/string/filters.rb
index 096292dc58..375ec1aef8 100644
--- a/activesupport/lib/active_support/core_ext/string/filters.rb
+++ b/activesupport/lib/active_support/core_ext/string/filters.rb
@@ -17,15 +17,15 @@ class String
   #   str.squish!                         # => "foo bar boo"
   #   str                                 # => "foo bar boo"
   def squish!
-    gsub!(/\A[[:space:]]+/, '')
-    gsub!(/[[:space:]]+\z/, '')
     gsub!(/[[:space:]]+/, ' ')
+    strip!
     self
   end
 
   # Returns a new string with all occurrences of the patterns removed.
   #   str = "foo bar test"
   #   str.remove(" test")                 # => "foo bar"
+  #   str.remove(" test", /bar/)          # => "foo "
   #   str                                 # => "foo bar test"
   def remove(*patterns)
     dup.remove!(*patterns)
@@ -33,8 +33,8 @@ class String
 
   # Alters the string by removing all occurrences of the patterns.
   #   str = "foo bar test"
-  #   str.remove!(" test")                 # => "foo bar"
-  #   str                                  # => "foo bar"
+  #   str.remove!(" test", /bar/)         # => "foo "
+  #   str                                 # => "foo "
   def remove!(*patterns)
     patterns.each do |pattern|
       gsub! pattern, ""
@@ -93,7 +93,7 @@ class String
   def truncate_words(words_count, options = {})
     sep = options[:separator] || /\s+/
     sep = Regexp.escape(sep.to_s) unless Regexp === sep
-    if self =~ /\A((?:.+?#{sep}){#{words_count - 1}}.+?)#{sep}.*/m
+    if self =~ /\A((?>.+?#{sep}){#{words_count - 1}}.+?)#{sep}.*/m
       $1 + (options[:omission] || '...')
     else
       dup
diff --git a/activesupport/lib/active_support/core_ext/string/inflections.rb b/activesupport/lib/active_support/core_ext/string/inflections.rb
index 38d567c014..b2e713077c 100644
--- a/activesupport/lib/active_support/core_ext/string/inflections.rb
+++ b/activesupport/lib/active_support/core_ext/string/inflections.rb
@@ -164,7 +164,7 @@ class String
   #
   #   <%= link_to(@person.name, person_path) %>
   #   # => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>
-  def parameterize(sep = '-')
+  def parameterize(sep = '-'.freeze)
     ActiveSupport::Inflector.parameterize(self, sep)
   end
 
@@ -172,17 +172,17 @@ class String
   # uses the +pluralize+ method on the last word in the string.
   #
   #   'RawScaledScorer'.tableize # => "raw_scaled_scorers"
-  #   'egg_and_ham'.tableize     # => "egg_and_hams"
+  #   'ham_and_egg'.tableize     # => "ham_and_eggs"
   #   'fancyCategory'.tableize   # => "fancy_categories"
   def tableize
     ActiveSupport::Inflector.tableize(self)
   end
 
-  # Create a class name from a plural table name like Rails does for table names to models.
+  # Creates a class name from a plural table name like Rails does for table names to models.
   # Note that this returns a string and not a class. (To convert to an actual class
   # follow +classify+ with +constantize+.)
   #
-  #   'egg_and_hams'.classify # => "EggAndHam"
+  #   'ham_and_eggs'.classify # => "HamAndEgg"
   #   'posts'.classify        # => "Post"
   def classify
     ActiveSupport::Inflector.classify(self)
diff --git a/activesupport/lib/active_support/core_ext/string/multibyte.rb b/activesupport/lib/active_support/core_ext/string/multibyte.rb
index a124202936..cc6f2158e7 100644
--- a/activesupport/lib/active_support/core_ext/string/multibyte.rb
+++ b/activesupport/lib/active_support/core_ext/string/multibyte.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'active_support/multibyte'
 
 class String
@@ -10,12 +9,10 @@ class String
   # encapsulates the original string. A Unicode safe version of all the String methods are defined on this proxy
   # class. If the proxy class doesn't respond to a certain method, it's forwarded to the encapsulated string.
   #
-  #   name = 'Claus Müller'
-  #   name.reverse # => "rell??M sualC"
-  #   name.length  # => 13
-  #
-  #   name.mb_chars.reverse.to_s # => "rellüM sualC"
-  #   name.mb_chars.length       # => 12
+  #   >> "lj".upcase
+  #   => "lj"
+  #   >> "lj".mb_chars.upcase.to_s
+  #   => "LJ"
   #
   # == Method chaining
   #
@@ -36,6 +33,13 @@ class String
     ActiveSupport::Multibyte.proxy_class.new(self)
   end
 
+  # Returns +true+ if string has utf_8 encoding.
+  #
+  #   utf_8_str = "some string".encode "UTF-8"
+  #   iso_str = "some string".encode "ISO-8859-1"
+  #
+  #   utf_8_str.is_utf8? # => true
+  #   iso_str.is_utf8?   # => false
   def is_utf8?
     case encoding
     when Encoding::UTF_8
diff --git a/activesupport/lib/active_support/core_ext/string/output_safety.rb b/activesupport/lib/active_support/core_ext/string/output_safety.rb
index ba8d4acd6d..510fa48189 100644
--- a/activesupport/lib/active_support/core_ext/string/output_safety.rb
+++ b/activesupport/lib/active_support/core_ext/string/output_safety.rb
@@ -13,7 +13,7 @@ class ERB
     # This method is also aliased as <tt>h</tt>.
     #
     # In your ERB templates, use this method to escape any unsafe content. For example:
-    #   <%=h @person.name %>
+    #   <%= h @person.name %>
     #
     #   puts html_escape('is a > 0 & a < 10?')
     #   # => is a &gt; 0 &amp; a &lt; 10?
@@ -37,7 +37,7 @@ class ERB
       if s.html_safe?
         s
       else
-        s.gsub(HTML_ESCAPE_REGEXP, HTML_ESCAPE)
+        ActiveSupport::Multibyte::Unicode.tidy_bytes(s).gsub(HTML_ESCAPE_REGEXP, HTML_ESCAPE)
       end
     end
     module_function :unwrapped_html_escape
@@ -50,7 +50,7 @@ class ERB
     #   html_escape_once('&lt;&lt; Accept & Checkout')
     #   # => "&lt;&lt; Accept &amp; Checkout"
     def html_escape_once(s)
-      result = s.to_s.gsub(HTML_ESCAPE_ONCE_REGEXP, HTML_ESCAPE)
+      result = ActiveSupport::Multibyte::Unicode.tidy_bytes(s.to_s).gsub(HTML_ESCAPE_ONCE_REGEXP, HTML_ESCAPE)
       s.html_safe? ? result.html_safe : result
     end
 
@@ -85,6 +85,11 @@ class ERB
     # automatically flag the result as HTML safe, since the raw value is unsafe to
     # use inside HTML attributes.
     #
+    # If your JSON is being used downstream for insertion into the DOM, be aware of
+    # whether or not it is being inserted via +html()+. Most jQuery plugins do this.
+    # If that is the case, be sure to +html_escape+ or +sanitize+ any user-generated
+    # content returned by your JSON.
+    #
     # If you need to output JSON elsewhere in your HTML, you can just do something
     # like this, as any unsafe characters (including quotation marks) will be
     # automatically escaped for you:
@@ -217,7 +222,7 @@ module ActiveSupport #:nodoc:
     end
 
     def encode_with(coder)
-      coder.represent_scalar nil, to_str
+      coder.represent_object nil, to_str
     end
 
     UNSAFE_STRING_METHODS.each do |unsafe_method|
diff --git a/activesupport/lib/active_support/core_ext/string/strip.rb b/activesupport/lib/active_support/core_ext/string/strip.rb
index 086c610976..55b9b87352 100644
--- a/activesupport/lib/active_support/core_ext/string/strip.rb
+++ b/activesupport/lib/active_support/core_ext/string/strip.rb
@@ -1,5 +1,3 @@
-require 'active_support/core_ext/object/try'
-
 class String
   # Strips indentation in heredocs.
   #
@@ -17,10 +15,9 @@ class String
   #
   # the user would see the usage message aligned against the left margin.
   #
-  # Technically, it looks for the least indented line in the whole string, and removes
-  # that amount of leading whitespace.
+  # Technically, it looks for the least indented non-empty line
+  # in the whole string, and removes that amount of leading whitespace.
   def strip_heredoc
-    indent = scan(/^[ \t]*(?=\S)/).min.try(:size) || 0
-    gsub(/^[ \t]{#{indent}}/, '')
+    gsub(/^#{scan(/^[ \t]*(?=\S)/).min}/, ''.freeze)
   end
 end
diff --git a/activesupport/lib/active_support/core_ext/time/calculations.rb b/activesupport/lib/active_support/core_ext/time/calculations.rb
index 649dc52865..82e003fc3b 100644
--- a/activesupport/lib/active_support/core_ext/time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/time/calculations.rb
@@ -3,6 +3,7 @@ require 'active_support/core_ext/time/conversions'
 require 'active_support/time_with_zone'
 require 'active_support/core_ext/time/zones'
 require 'active_support/core_ext/date_and_time/calculations'
+require 'active_support/core_ext/date/calculations'
 
 class Time
   include DateAndTime::Calculations
@@ -15,9 +16,9 @@ class Time
       super || (self == Time && other.is_a?(ActiveSupport::TimeWithZone))
     end
 
-    # Return the number of days in the given month.
+    # Returns the number of days in the given month.
     # If no year is specified, it will use the current year.
-    def days_in_month(month, year = now.year)
+    def days_in_month(month, year = current.year)
       if month == 2 && ::Date.gregorian_leap?(year)
         29
       else
@@ -48,7 +49,11 @@ class Time
     alias_method :at, :at_with_coercion
   end
 
-  # Seconds since midnight: Time.now.seconds_since_midnight
+  # Returns the number of seconds since 00:00:00.
+  #
+  #   Time.new(2012, 8, 29,  0,  0,  0).seconds_since_midnight # => 0.0
+  #   Time.new(2012, 8, 29, 12, 34, 56).seconds_since_midnight # => 45296.0
+  #   Time.new(2012, 8, 29, 23, 59, 59).seconds_since_midnight # => 86399.0
   def seconds_since_midnight
     to_i - change(:hour => 0).to_i + (usec / 1.0e+6)
   end
@@ -69,7 +74,7 @@ class Time
   # and minute is passed, then sec, usec and nsec is set to 0. The +options+
   # parameter takes a hash with any of these keys: <tt>:year</tt>, <tt>:month</tt>,
   # <tt>:day</tt>, <tt>:hour</tt>, <tt>:min</tt>, <tt>:sec</tt>, <tt>:usec</tt>
-  # <tt>:nsec</tt>. Path either <tt>:usec</tt> or <tt>:nsec</tt>, not both.
+  # <tt>:nsec</tt>. Pass either <tt>:usec</tt> or <tt>:nsec</tt>, not both.
   #
   #   Time.new(2012, 8, 29, 22, 35, 0).change(day: 1)              # => Time.new(2012, 8, 1, 22, 35, 0)
   #   Time.new(2012, 8, 29, 22, 35, 0).change(year: 1981, day: 1)  # => Time.new(1981, 8, 1, 22, 35, 0)
@@ -94,7 +99,7 @@ class Time
     elsif zone
       ::Time.local(new_year, new_month, new_day, new_hour, new_min, new_sec, new_usec)
     else
-      raise ArgumentError, 'argument out of range' if new_usec > 999999
+      raise ArgumentError, 'argument out of range' if new_usec >= 1000000
       ::Time.new(new_year, new_month, new_day, new_hour, new_min, new_sec + (new_usec.to_r / 1000000), utc_offset)
     end
   end
@@ -104,6 +109,12 @@ class Time
   # takes a hash with any of these keys: <tt>:years</tt>, <tt>:months</tt>,
   # <tt>:weeks</tt>, <tt>:days</tt>, <tt>:hours</tt>, <tt>:minutes</tt>,
   # <tt>:seconds</tt>.
+  #
+  #   Time.new(2015, 8, 1, 14, 35, 0).advance(seconds: 1) # => 2015-08-01 14:35:01 -0700
+  #   Time.new(2015, 8, 1, 14, 35, 0).advance(minutes: 1) # => 2015-08-01 14:36:00 -0700
+  #   Time.new(2015, 8, 1, 14, 35, 0).advance(hours: 1)   # => 2015-08-01 15:35:00 -0700
+  #   Time.new(2015, 8, 1, 14, 35, 0).advance(days: 1)    # => 2015-08-02 14:35:00 -0700
+  #   Time.new(2015, 8, 1, 14, 35, 0).advance(weeks: 1)   # => 2015-08-08 14:35:00 -0700
   def advance(options)
     unless options[:weeks].nil?
       options[:weeks], partial_weeks = options[:weeks].divmod(1)
@@ -242,8 +253,10 @@ class Time
   # Layers additional behavior on Time#<=> so that DateTime and ActiveSupport::TimeWithZone instances
   # can be chronologically compared with a Time
   def compare_with_coercion(other)
-    # we're avoiding Time#to_datetime cause it's expensive
-    if other.is_a?(Time)
+    # we're avoiding Time#to_datetime and Time#to_time because they're expensive
+    if other.class == Time
+      compare_without_coercion(other)
+    elsif other.is_a?(Time)
       compare_without_coercion(other.to_time)
     else
       to_datetime <=> other
diff --git a/activesupport/lib/active_support/core_ext/time/conversions.rb b/activesupport/lib/active_support/core_ext/time/conversions.rb
index dbf1f2f373..536c4bf525 100644
--- a/activesupport/lib/active_support/core_ext/time/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/time/conversions.rb
@@ -6,6 +6,7 @@ class Time
     :db           => '%Y-%m-%d %H:%M:%S',
     :number       => '%Y%m%d%H%M%S',
     :nsec         => '%Y%m%d%H%M%S%9N',
+    :usec         => '%Y%m%d%H%M%S%6N',
     :time         => '%H:%M',
     :short        => '%d %b %H:%M',
     :long         => '%B %d, %Y %H:%M',
@@ -24,7 +25,7 @@ class Time
   #
   # This method is aliased to <tt>to_s</tt>.
   #
-  #   time = Time.now                    # => Thu Jan 18 06:10:17 CST 2007
+  #   time = Time.now                    # => 2007-01-18 06:10:17 -06:00
   #
   #   time.to_formatted_s(:time)         # => "06:10"
   #   time.to_s(:time)                   # => "06:10"
@@ -55,7 +56,8 @@ class Time
   alias_method :to_default_s, :to_s
   alias_method :to_s, :to_formatted_s
 
-  # Returns the UTC offset as an +HH:MM formatted string.
+  # Returns a formatted string of the offset from UTC, or an alternative
+  # string if the time zone is already UTC.
   #
   #   Time.local(2000).formatted_offset        # => "-06:00"
   #   Time.local(2000).formatted_offset(false) # => "-0600"
diff --git a/activesupport/lib/active_support/core_ext/time/zones.rb b/activesupport/lib/active_support/core_ext/time/zones.rb
index 0668eadb1e..877dc84ec8 100644
--- a/activesupport/lib/active_support/core_ext/time/zones.rb
+++ b/activesupport/lib/active_support/core_ext/time/zones.rb
@@ -26,7 +26,7 @@ class Time
     # <tt>current_user.time_zone</tt> just needs to return a string identifying the user's preferred time zone:
     #
     #   class ApplicationController < ActionController::Base
-    #     around_filter :set_time_zone
+    #     around_action :set_time_zone
     #
     #     def set_time_zone
     #       if logged_in?
@@ -53,7 +53,7 @@ class Time
 
     # Returns a TimeZone instance matching the time zone provided.
     # Accepts the time zone in any format supported by <tt>Time.zone=</tt>.
-    # Raises an ArgumentError for invalid time zones.
+    # Raises an +ArgumentError+ for invalid time zones.
     #
     #   Time.find_zone! "America/New_York" # => #<ActiveSupport::TimeZone @name="America/New_York" ...>
     #   Time.find_zone! "EST"              # => #<ActiveSupport::TimeZone @name="EST" ...>
@@ -65,7 +65,8 @@ class Time
       if !time_zone || time_zone.is_a?(ActiveSupport::TimeZone)
         time_zone
       else
-        # lookup timezone based on identifier (unless we've been passed a TZInfo::Timezone)
+        # Look up the timezone based on the identifier (unless we've been
+        # passed a TZInfo::Timezone)
         unless time_zone.respond_to?(:period_for_local)
           time_zone = ActiveSupport::TimeZone[time_zone] || TZInfo::Timezone.get(time_zone)
         end
diff --git a/activesupport/lib/active_support/core_ext/uri.rb b/activesupport/lib/active_support/core_ext/uri.rb
index bfe0832b37..c6c183edd9 100644
--- a/activesupport/lib/active_support/core_ext/uri.rb
+++ b/activesupport/lib/active_support/core_ext/uri.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 require 'uri'
 str = "\xE6\x97\xA5\xE6\x9C\xAC\xE8\xAA\x9E" # Ni-ho-nn-go in UTF-8, means Japanese.
 parser = URI::Parser.new
@@ -12,7 +10,7 @@ unless str == parser.unescape(parser.escape(str))
       # YK: My initial experiments say yes, but let's be sure please
       enc = str.encoding
       enc = Encoding::UTF_8 if enc == Encoding::US_ASCII
-      str.gsub(escaped) { [$&[1, 2].hex].pack('C') }.force_encoding(enc)
+      str.gsub(escaped) { |match| [match[1, 2].hex].pack('C') }.force_encoding(enc)
     end
   end
 end
diff --git a/activesupport/lib/active_support/dependencies.rb b/activesupport/lib/active_support/dependencies.rb
index e03e7c30d8..16b726bcba 100644
--- a/activesupport/lib/active_support/dependencies.rb
+++ b/activesupport/lib/active_support/dependencies.rb
@@ -1,6 +1,6 @@
 require 'set'
 require 'thread'
-require 'thread_safe'
+require 'concurrent'
 require 'pathname'
 require 'active_support/core_ext/module/aliasing'
 require 'active_support/core_ext/module/attribute_accessors'
@@ -12,12 +12,40 @@ require 'active_support/core_ext/kernel/reporting'
 require 'active_support/core_ext/load_error'
 require 'active_support/core_ext/name_error'
 require 'active_support/core_ext/string/starts_ends_with'
+require "active_support/dependencies/interlock"
 require 'active_support/inflector'
 
 module ActiveSupport #:nodoc:
   module Dependencies #:nodoc:
     extend self
 
+    mattr_accessor :interlock
+    self.interlock = Interlock.new
+
+    # :doc:
+
+    # Execute the supplied block without interference from any
+    # concurrent loads
+    def self.run_interlock
+      Dependencies.interlock.running { yield }
+    end
+
+    # Execute the supplied block while holding an exclusive lock,
+    # preventing any other thread from being inside a #run_interlock
+    # block at the same time
+    def self.load_interlock
+      Dependencies.interlock.loading { yield }
+    end
+
+    # Execute the supplied block while holding an exclusive lock,
+    # preventing any other thread from being inside a #run_interlock
+    # block at the same time
+    def self.unload_interlock
+      Dependencies.interlock.unloading { yield }
+    end
+
+    # :nodoc:
+
     # Should we turn on Ruby warnings on the first load of dependent files?
     mattr_accessor :warnings_on_first_load
     self.warnings_on_first_load = false
@@ -128,7 +156,7 @@ module ActiveSupport #:nodoc:
 
           # Normalize the list of new constants, and add them to the list we will return
           new_constants.each do |suffix|
-            constants << ([namespace, suffix] - ["Object"]).join("::")
+            constants << ([namespace, suffix] - ["Object"]).join("::".freeze)
           end
         end
         constants
@@ -325,9 +353,11 @@ module ActiveSupport #:nodoc:
 
     def clear
       log_call
-      loaded.clear
-      loading.clear
-      remove_unloadable_constants!
+      Dependencies.unload_interlock do
+        loaded.clear
+        loading.clear
+        remove_unloadable_constants!
+      end
     end
 
     def require_or_load(file_name, const_path = nil)
@@ -336,44 +366,49 @@ module ActiveSupport #:nodoc:
       expanded = File.expand_path(file_name)
       return if loaded.include?(expanded)
 
-      # Record that we've seen this file *before* loading it to avoid an
-      # infinite loop with mutual dependencies.
-      loaded << expanded
-      loading << expanded
+      Dependencies.load_interlock do
+        # Maybe it got loaded while we were waiting for our lock:
+        return if loaded.include?(expanded)
 
-      begin
-        if load?
-          log "loading #{file_name}"
+        # Record that we've seen this file *before* loading it to avoid an
+        # infinite loop with mutual dependencies.
+        loaded << expanded
+        loading << expanded
 
-          # Enable warnings if this file has not been loaded before and
-          # warnings_on_first_load is set.
-          load_args = ["#{file_name}.rb"]
-          load_args << const_path unless const_path.nil?
-
-          if !warnings_on_first_load or history.include?(expanded)
-            result = load_file(*load_args)
+        begin
+          if load?
+            log "loading #{file_name}"
+
+            # Enable warnings if this file has not been loaded before and
+            # warnings_on_first_load is set.
+            load_args = ["#{file_name}.rb"]
+            load_args << const_path unless const_path.nil?
+
+            if !warnings_on_first_load or history.include?(expanded)
+              result = load_file(*load_args)
+            else
+              enable_warnings { result = load_file(*load_args) }
+            end
           else
-            enable_warnings { result = load_file(*load_args) }
+            log "requiring #{file_name}"
+            result = require file_name
           end
-        else
-          log "requiring #{file_name}"
-          result = require file_name
+        rescue Exception
+          loaded.delete expanded
+          raise
+        ensure
+          loading.pop
         end
-      rescue Exception
-        loaded.delete expanded
-        raise
-      ensure
-        loading.pop
-      end
 
-      # Record history *after* loading so first load gets warnings.
-      history << expanded
-      result
+        # Record history *after* loading so first load gets warnings.
+        history << expanded
+        result
+      end
     end
 
     # Is the provided constant path defined?
     def qualified_const_defined?(path)
-      Object.qualified_const_defined?(path.sub(/^::/, ''), false)
+      Object.const_defined?(path, false)
     end
 
     # Given +path+, a filesystem path to a ruby file, return an array of
@@ -386,13 +421,13 @@ module ActiveSupport #:nodoc:
 
       bases.each do |root|
         expanded_root = File.expand_path(root)
-        next unless %r{\A#{Regexp.escape(expanded_root)}(/|\\)} =~ expanded_path
+        next unless expanded_path.start_with?(expanded_root)
 
-        nesting = expanded_path[(expanded_root.size)..-1]
-        nesting = nesting[1..-1] if nesting && nesting[0] == ?/
-        next if nesting.blank?
+        root_size = expanded_root.size
+        next if expanded_path[root_size] != ?/.freeze
 
-        paths << nesting.camelize
+        nesting = expanded_path[(root_size + 1)..-1]
+        paths << nesting.camelize unless nesting.blank?
       end
 
       paths.uniq!
@@ -401,7 +436,7 @@ module ActiveSupport #:nodoc:
 
     # Search for a file in autoload_paths matching the provided suffix.
     def search_for_file(path_suffix)
-      path_suffix = path_suffix.sub(/(\.rb)?$/, ".rb")
+      path_suffix = path_suffix.sub(/(\.rb)?$/, ".rb".freeze)
 
       autoload_paths.each do |root|
         path = File.join(root, path_suffix)
@@ -486,7 +521,7 @@ module ActiveSupport #:nodoc:
 
       if file_path
         expanded = File.expand_path(file_path)
-        expanded.sub!(/\.rb\z/, '')
+        expanded.sub!(/\.rb\z/, ''.freeze)
 
         if loading.include?(expanded)
           raise "Circular dependency detected while autoloading constant #{qualified_name}"
@@ -550,7 +585,7 @@ module ActiveSupport #:nodoc:
 
     class ClassCache
       def initialize
-        @store = ThreadSafe::Cache.new
+        @store = Concurrent::Map.new
       end
 
       def empty?
@@ -607,7 +642,7 @@ module ActiveSupport #:nodoc:
     def autoloaded?(desc)
       return false if desc.is_a?(Module) && desc.anonymous?
       name = to_constant_name desc
-      return false unless qualified_const_defined? name
+      return false unless qualified_const_defined?(name)
       return autoloaded_constants.include?(name)
     end
 
diff --git a/activesupport/lib/active_support/dependencies/interlock.rb b/activesupport/lib/active_support/dependencies/interlock.rb
new file mode 100644
index 0000000000..fbeb904684
--- /dev/null
+++ b/activesupport/lib/active_support/dependencies/interlock.rb
@@ -0,0 +1,47 @@
+require 'active_support/concurrency/share_lock'
+
+module ActiveSupport #:nodoc:
+  module Dependencies #:nodoc:
+    class Interlock
+      def initialize # :nodoc:
+        @lock = ActiveSupport::Concurrency::ShareLock.new
+      end
+
+      def loading
+        @lock.exclusive(purpose: :load, compatible: [:load]) do
+          yield
+        end
+      end
+
+      def unloading
+        @lock.exclusive(purpose: :unload, compatible: [:load, :unload]) do
+          yield
+        end
+      end
+
+      # Attempt to obtain an "unloading" (exclusive) lock. If possible,
+      # execute the supplied block while holding the lock. If there is
+      # concurrent activity, return immediately (without executing the
+      # block) instead of waiting.
+      def attempt_unloading
+        @lock.exclusive(purpose: :unload, compatible: [:load, :unload], no_wait: true) do
+          yield
+        end
+      end
+
+      def start_running
+        @lock.start_sharing
+      end
+
+      def done_running
+        @lock.stop_sharing
+      end
+
+      def running
+        @lock.sharing do
+          yield
+        end
+      end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/deprecation/behaviors.rb b/activesupport/lib/active_support/deprecation/behaviors.rb
index 9f9dca8453..28d2d78643 100644
--- a/activesupport/lib/active_support/deprecation/behaviors.rb
+++ b/activesupport/lib/active_support/deprecation/behaviors.rb
@@ -38,6 +38,18 @@ module ActiveSupport
       silence: ->(message, callstack) {},
     }
 
+    # Behavior module allows to determine how to display deprecation messages.
+    # You can create a custom behavior or set any from the +DEFAULT_BEHAVIORS+
+    # constant. Available behaviors are:
+    #
+    # [+raise+]   Raise <tt>ActiveSupport::DeprecationException</tt>.
+    # [+stderr+]  Log all deprecation warnings to +$stderr+.
+    # [+log+]     Log all deprecation warnings to +Rails.logger+.
+    # [+notify+]  Use +ActiveSupport::Notifications+ to notify +deprecation.rails+.
+    # [+silence+] Do nothing.
+    #
+    # Setting behaviors only affects deprecations that happen after boot time.
+    # For more information you can read the documentation of the +behavior=+ method.
     module Behavior
       # Whether to print a backtrace along with the warning.
       attr_accessor :debug
diff --git a/activesupport/lib/active_support/deprecation/method_wrappers.rb b/activesupport/lib/active_support/deprecation/method_wrappers.rb
index cab8a1b14d..32fe8025fe 100644
--- a/activesupport/lib/active_support/deprecation/method_wrappers.rb
+++ b/activesupport/lib/active_support/deprecation/method_wrappers.rb
@@ -9,35 +9,61 @@ module ActiveSupport
       #   module Fred
       #     extend self
       #
-      #     def foo; end
-      #     def bar; end
-      #     def baz; end
+      #     def aaa; end
+      #     def bbb; end
+      #     def ccc; end
+      #     def ddd; end
+      #     def eee; end
       #   end
       #
-      #   ActiveSupport::Deprecation.deprecate_methods(Fred, :foo, bar: :qux, baz: 'use Bar#baz instead')
-      #   # => [:foo, :bar, :baz]
+      # Using the default deprecator:
+      #   ActiveSupport::Deprecation.deprecate_methods(Fred, :aaa, bbb: :zzz, ccc: 'use Bar#ccc instead')
+      #   # => [:aaa, :bbb, :ccc]
       #
-      #   Fred.foo
-      #   # => "DEPRECATION WARNING: foo is deprecated and will be removed from Rails 4.1."
+      #   Fred.aaa
+      #   # DEPRECATION WARNING: aaa is deprecated and will be removed from Rails 5.0. (called from irb_binding at (irb):10)
+      #   # => nil
       #
-      #   Fred.bar
-      #   # => "DEPRECATION WARNING: bar is deprecated and will be removed from Rails 4.1 (use qux instead)."
+      #   Fred.bbb
+      #   # DEPRECATION WARNING: bbb is deprecated and will be removed from Rails 5.0 (use zzz instead). (called from irb_binding at (irb):11)
+      #   # => nil
       #
-      #   Fred.baz
-      #   # => "DEPRECATION WARNING: baz is deprecated and will be removed from Rails 4.1 (use Bar#baz instead)."
+      #   Fred.ccc
+      #   # DEPRECATION WARNING: ccc is deprecated and will be removed from Rails 5.0 (use Bar#ccc instead). (called from irb_binding at (irb):12)
+      #   # => nil
+      #
+      # Passing in a custom deprecator:
+      #   custom_deprecator = ActiveSupport::Deprecation.new('next-release', 'MyGem')
+      #   ActiveSupport::Deprecation.deprecate_methods(Fred, ddd: :zzz, deprecator: custom_deprecator)
+      #   # => [:ddd]
+      #
+      #   Fred.ddd
+      #   DEPRECATION WARNING: ddd is deprecated and will be removed from MyGem next-release (use zzz instead). (called from irb_binding at (irb):15)
+      #   # => nil
+      #
+      # Using a custom deprecator directly:
+      #   custom_deprecator = ActiveSupport::Deprecation.new('next-release', 'MyGem')
+      #   custom_deprecator.deprecate_methods(Fred, eee: :zzz)
+      #   # => [:eee]
+      #
+      #   Fred.eee
+      #   DEPRECATION WARNING: eee is deprecated and will be removed from MyGem next-release (use zzz instead). (called from irb_binding at (irb):18)
+      #   # => nil
       def deprecate_methods(target_module, *method_names)
         options = method_names.extract_options!
-        deprecator = options.delete(:deprecator) || ActiveSupport::Deprecation.instance
+        deprecator = options.delete(:deprecator) || self
         method_names += options.keys
 
-        method_names.each do |method_name|
-          target_module.alias_method_chain(method_name, :deprecation) do |target, punctuation|
-            target_module.send(:define_method, "#{target}_with_deprecation#{punctuation}") do |*args, &block|
+        mod = Module.new do
+          method_names.each do |method_name|
+            define_method(method_name) do |*args, &block|
               deprecator.deprecation_warning(method_name, options[method_name])
-              send(:"#{target}_without_deprecation#{punctuation}", *args, &block)
+              super(*args, &block)
             end
           end
         end
+
+        target_module.prepend(mod)
       end
     end
   end
diff --git a/activesupport/lib/active_support/deprecation/proxy_wrappers.rb b/activesupport/lib/active_support/deprecation/proxy_wrappers.rb
index a03a66b96b..6f0ad445fc 100644
--- a/activesupport/lib/active_support/deprecation/proxy_wrappers.rb
+++ b/activesupport/lib/active_support/deprecation/proxy_wrappers.rb
@@ -20,20 +20,22 @@ module ActiveSupport
 
       private
         def method_missing(called, *args, &block)
-          warn caller, called, args
+          warn caller_locations, called, args
           target.__send__(called, *args, &block)
         end
     end
 
-    # This DeprecatedObjectProxy transforms object to deprecated object.
+    # DeprecatedObjectProxy transforms an object into a deprecated one. It
+    # takes an object, a deprecation message and optionally a deprecator. The
+    # deprecator defaults to +ActiveSupport::Deprecator+ if none is specified.
     #
-    #   @old_object = DeprecatedObjectProxy.new(Object.new, "Don't use this object anymore!")
-    #   @old_object = DeprecatedObjectProxy.new(Object.new, "Don't use this object anymore!", deprecator_instance)
+    #   deprecated_object = ActiveSupport::Deprecation::DeprecatedObjectProxy.new(Object.new, "This object is now deprecated")
+    #   # => #<Object:0x007fb9b34c34b0>
     #
-    # When someone executes any method except +inspect+ on proxy object this will
-    # trigger +warn+ method on +deprecator_instance+.
-    #
-    # Default deprecator is <tt>ActiveSupport::Deprecation</tt>
+    #   deprecated_object.to_s
+    #   DEPRECATION WARNING: This object is now deprecated.
+    #   (Backtrace)
+    #   # => "#<Object:0x007fb9b34c34b0>"
     class DeprecatedObjectProxy < DeprecationProxy
       def initialize(object, message, deprecator = ActiveSupport::Deprecation.instance)
         @object = object
@@ -51,13 +53,16 @@ module ActiveSupport
         end
     end
 
-    # This DeprecatedInstanceVariableProxy transforms instance variable to
-    # deprecated instance variable.
+    # DeprecatedInstanceVariableProxy transforms an instance variable into a
+    # deprecated one. It takes an instance of a class, a method on that class
+    # and an instance variable. It optionally takes a deprecator as the last
+    # argument. The deprecator defaults to +ActiveSupport::Deprecator+ if none
+    # is specified.
     #
     #   class Example
-    #     def initialize(deprecator)
-    #       @request = ActiveSupport::Deprecation::DeprecatedInstanceVariableProxy.new(self, :request, :@request, deprecator)
-    #       @_request = :a_request
+    #     def initialize
+    #       @request = ActiveSupport::Deprecation::DeprecatedInstanceVariableProxy.new(self, :request, :@request)
+    #       @_request = :special_request
     #     end
     #
     #     def request
@@ -69,12 +74,17 @@ module ActiveSupport
     #     end
     #   end
     #
-    # When someone execute any method on @request variable this will trigger
-    # +warn+ method on +deprecator_instance+ and will fetch <tt>@_request</tt>
-    # variable via +request+ method and execute the same method on non-proxy
-    # instance variable.
+    #   example = Example.new
+    #   # => #<Example:0x007fb9b31090b8 @_request=:special_request, @request=:special_request>
+    #
+    #   example.old_request.to_s
+    #   # => DEPRECATION WARNING: @request is deprecated! Call request.to_s instead of
+    #      @request.to_s
+    #      (Bactrace information…)
+    #      "special_request"
     #
-    # Default deprecator is <tt>ActiveSupport::Deprecation</tt>.
+    #   example.request.to_s
+    #   # => "special_request"
     class DeprecatedInstanceVariableProxy < DeprecationProxy
       def initialize(instance, method, var = "@#{method}", deprecator = ActiveSupport::Deprecation.instance)
         @instance = instance
@@ -93,15 +103,23 @@ module ActiveSupport
         end
     end
 
-    # This DeprecatedConstantProxy transforms constant to deprecated constant.
+    # DeprecatedConstantProxy transforms a constant into a deprecated one. It
+    # takes the names of an old (deprecated) constant and of a new constant
+    # (both in string form) and optionally a deprecator. The deprecator defaults
+    # to +ActiveSupport::Deprecator+ if none is specified. The deprecated constant
+    # now returns the value of the new one.
+    #
+    #   PLANETS = %w(mercury venus earth mars jupiter saturn uranus neptune pluto)
     #
-    #   OLD_CONST = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('OLD_CONST', 'NEW_CONST')
-    #   OLD_CONST = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('OLD_CONST', 'NEW_CONST', deprecator_instance)
+    #   (In a later update, the original implementation of `PLANETS` has been removed.)
     #
-    # When someone use old constant this will trigger +warn+ method on
-    # +deprecator_instance+.
+    #   PLANETS_POST_2006 = %w(mercury venus earth mars jupiter saturn uranus neptune)
+    #   PLANETS = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('PLANETS', 'PLANETS_POST_2006')
     #
-    # Default deprecator is <tt>ActiveSupport::Deprecation</tt>.
+    #   PLANETS.map { |planet| planet.capitalize }
+    #   # => DEPRECATION WARNING: PLANETS is deprecated! Use PLANETS_POST_2006 instead.
+    #        (Bactrace information…)
+    #        ["Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune"]
     class DeprecatedConstantProxy < DeprecationProxy
       def initialize(old_const, new_const, deprecator = ActiveSupport::Deprecation.instance)
         @old_const = old_const
@@ -109,6 +127,11 @@ module ActiveSupport
         @deprecator = deprecator
       end
 
+      # Returns the class of the new constant.
+      #
+      #   PLANETS_POST_2006 = %w(mercury venus earth mars jupiter saturn uranus neptune)
+      #   PLANETS = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('PLANETS', 'PLANETS_POST_2006')
+      #   PLANETS.class # => Array
       def class
         target.class
       end
diff --git a/activesupport/lib/active_support/deprecation/reporting.rb b/activesupport/lib/active_support/deprecation/reporting.rb
index a7d265d732..bbe25c9260 100644
--- a/activesupport/lib/active_support/deprecation/reporting.rb
+++ b/activesupport/lib/active_support/deprecation/reporting.rb
@@ -14,7 +14,7 @@ module ActiveSupport
       def warn(message = nil, callstack = nil)
         return if silenced
 
-        callstack ||= caller(2)
+        callstack ||= caller_locations(2)
         deprecation_message(callstack, message).tap do |m|
           behavior.each { |b| b.call(m, callstack) }
         end
@@ -37,7 +37,7 @@ module ActiveSupport
       end
 
       def deprecation_warning(deprecated_method_name, message = nil, caller_backtrace = nil)
-        caller_backtrace ||= caller(2)
+        caller_backtrace ||= caller_locations(2)
         deprecated_method_warning(deprecated_method_name, message).tap do |msg|
           warn(msg, caller_backtrace)
         end
@@ -79,6 +79,17 @@ module ActiveSupport
         end
 
         def extract_callstack(callstack)
+          return _extract_callstack(callstack) if callstack.first.is_a? String
+
+          rails_gem_root = File.expand_path("../../../../..", __FILE__) + "/"
+          offending_line = callstack.find { |frame|
+            !frame.absolute_path.start_with?(rails_gem_root)
+          } || callstack.first
+          [offending_line.path, offending_line.lineno, offending_line.label]
+        end
+
+        def _extract_callstack(callstack)
+          warn "Please pass `caller_locations` to the deprecation API" if $VERBOSE
           rails_gem_root = File.expand_path("../../../../..", __FILE__) + "/"
           offending_line = callstack.find { |line| !line.start_with?(rails_gem_root) } || callstack.first
           if offending_line
diff --git a/activesupport/lib/active_support/duration.rb b/activesupport/lib/active_support/duration.rb
index 5a64fc52cc..c63b61e97a 100644
--- a/activesupport/lib/active_support/duration.rb
+++ b/activesupport/lib/active_support/duration.rb
@@ -52,10 +52,38 @@ module ActiveSupport
       end
     end
 
+    # Returns the amount of seconds a duration covers as a string.
+    # For more information check to_i method.
+    #
+    #   1.day.to_s # => "86400"
     def to_s
       @value.to_s
     end
 
+    # Returns the number of seconds that this Duration represents.
+    #
+    #   1.minute.to_i   # => 60
+    #   1.hour.to_i     # => 3600
+    #   1.day.to_i      # => 86400
+    #
+    # Note that this conversion makes some assumptions about the
+    # duration of some periods, e.g. months are always 30 days
+    # and years are 365.25 days:
+    #
+    #   # equivalent to 30.days.to_i
+    #   1.month.to_i    # => 2592000
+    #
+    #   # equivalent to 365.25.days.to_i
+    #   1.year.to_i     # => 31557600
+    #
+    # In such cases, Ruby's core
+    # Date[http://ruby-doc.org/stdlib/libdoc/date/rdoc/Date.html] and
+    # Time[http://ruby-doc.org/stdlib/libdoc/time/rdoc/Time.html] should be used for precision
+    # date and time arithmetic.
+    def to_i
+      @value.to_i
+    end
+
     # Returns +true+ if +other+ is also a Duration instance, which has the
     # same parts as this one.
     def eql?(other)
diff --git a/activesupport/lib/active_support/hash_with_indifferent_access.rb b/activesupport/lib/active_support/hash_with_indifferent_access.rb
index 1468c62151..0371f760b0 100644
--- a/activesupport/lib/active_support/hash_with_indifferent_access.rb
+++ b/activesupport/lib/active_support/hash_with_indifferent_access.rb
@@ -92,7 +92,7 @@ module ActiveSupport
     #   hash = ActiveSupport::HashWithIndifferentAccess.new
     #   hash[:key] = 'value'
     #
-    # This value can be later fetched using either +:key+ or +'key'+.
+    # This value can be later fetched using either +:key+ or <tt>'key'</tt>.
     def []=(key, value)
       regular_writer(convert_key(key), convert_value(value, for: :assignment))
     end
@@ -188,7 +188,7 @@ module ActiveSupport
     #   dup[:a][:c]  # => "c"
     def dup
       self.class.new(self).tap do |new_hash|
-        new_hash.default = default
+        set_defaults(new_hash)
       end
     end
 
@@ -238,16 +238,20 @@ module ActiveSupport
     def to_options!; self end
 
     def select(*args, &block)
+      return to_enum(:select) unless block_given?
       dup.tap { |hash| hash.select!(*args, &block) }
     end
 
     def reject(*args, &block)
+      return to_enum(:reject) unless block_given?
       dup.tap { |hash| hash.reject!(*args, &block) }
     end
 
     # Convert to a regular hash with string keys.
     def to_hash
-      _new_hash = Hash.new(default)
+      _new_hash = Hash.new
+      set_defaults(_new_hash)
+
       each do |key, value|
         _new_hash[key] = convert_value(value, for: :to_hash)
       end
@@ -267,7 +271,7 @@ module ActiveSupport
             value.nested_under_indifferent_access
           end
         elsif value.is_a?(Array)
-          unless options[:for] == :assignment
+          if options[:for] != :assignment || value.frozen?
             value = value.dup
           end
           value.map! { |e| convert_value(e, options) }
@@ -275,6 +279,14 @@ module ActiveSupport
           value
         end
       end
+
+      def set_defaults(target)
+        if default_proc
+          target.default_proc = default_proc.dup
+        else
+          target.default = default
+        end
+      end
   end
 end
 
diff --git a/activesupport/lib/active_support/i18n_railtie.rb b/activesupport/lib/active_support/i18n_railtie.rb
index 9e742b1917..6775eec34b 100644
--- a/activesupport/lib/active_support/i18n_railtie.rb
+++ b/activesupport/lib/active_support/i18n_railtie.rb
@@ -37,10 +37,12 @@ module I18n
       enforce_available_locales = I18n.enforce_available_locales if enforce_available_locales.nil?
       I18n.enforce_available_locales = false
 
+      reloadable_paths = []
       app.config.i18n.each do |setting, value|
         case setting
         when :railties_load_path
-          app.config.i18n.load_path.unshift(*value)
+          reloadable_paths = value
+          app.config.i18n.load_path.unshift(*value.map(&:existent).flatten)
         when :load_path
           I18n.load_path += value
         else
@@ -53,7 +55,14 @@ module I18n
       # Restore available locales check so it will take place from now on.
       I18n.enforce_available_locales = enforce_available_locales
 
-      reloader = ActiveSupport::FileUpdateChecker.new(I18n.load_path.dup){ I18n.reload! }
+      directories = watched_dirs_with_extensions(reloadable_paths)
+      reloader = ActiveSupport::FileUpdateChecker.new(I18n.load_path.dup, directories) do
+        I18n.load_path.keep_if { |p| File.exist?(p) }
+        I18n.load_path |= reloadable_paths.map(&:existent).flatten
+
+        I18n.reload!
+      end
+
       app.reloaders << reloader
       ActionDispatch::Reloader.to_prepare do
         reloader.execute_if_updated
@@ -68,7 +77,7 @@ module I18n
     end
 
     def self.include_fallbacks_module
-      I18n.backend.class.send(:include, I18n::Backend::Fallbacks)
+      I18n.backend.class.include(I18n::Backend::Fallbacks)
     end
 
     def self.init_fallbacks(fallbacks)
@@ -96,5 +105,11 @@ module I18n
         raise "Unexpected fallback type #{fallbacks.inspect}"
       end
     end
+
+    def self.watched_dirs_with_extensions(paths)
+      paths.each_with_object({}) do |path, result|
+        result[path.absolute_current] = path.extensions
+      end
+    end
   end
 end
diff --git a/activesupport/lib/active_support/inflector/inflections.rb b/activesupport/lib/active_support/inflector/inflections.rb
index 486838bd15..c3907e9c22 100644
--- a/activesupport/lib/active_support/inflector/inflections.rb
+++ b/activesupport/lib/active_support/inflector/inflections.rb
@@ -1,4 +1,4 @@
-require 'thread_safe'
+require 'concurrent'
 require 'active_support/core_ext/array/prepend_and_append'
 require 'active_support/i18n'
 
@@ -25,7 +25,38 @@ module ActiveSupport
     # singularization rules that is runs. This guarantees that your rules run
     # before any of the rules that may already have been loaded.
     class Inflections
-      @__instance__ = ThreadSafe::Cache.new
+      @__instance__ = Concurrent::Map.new
+
+      class Uncountables < Array
+        def initialize
+          @regex_array = []
+          super
+        end
+
+        def delete(entry)
+          super entry
+          @regex_array.delete(to_regex(entry))
+        end
+
+        def <<(*word)
+          add(word)
+        end
+
+        def add(words)
+          self.concat(words.flatten.map(&:downcase))
+          @regex_array += self.map {|word|  to_regex(word) }
+          self
+        end
+
+        def uncountable?(str)
+          @regex_array.any? { |regex| regex === str }
+        end
+
+        private
+          def to_regex(string)
+            /\b#{::Regexp.escape(string)}\Z/i
+          end
+      end
 
       def self.instance(locale = :en)
         @__instance__[locale] ||= new
@@ -34,7 +65,7 @@ module ActiveSupport
       attr_reader :plurals, :singulars, :uncountables, :humans, :acronyms, :acronym_regex
 
       def initialize
-        @plurals, @singulars, @uncountables, @humans, @acronyms, @acronym_regex = [], [], [], [], {}, /(?=a)b/
+        @plurals, @singulars, @uncountables, @humans, @acronyms, @acronym_regex = [], [], Uncountables.new, [], {}, /(?=a)b/
       end
 
       # Private, for the test suite.
@@ -160,7 +191,7 @@ module ActiveSupport
       #   uncountable 'money', 'information'
       #   uncountable %w( money information rice )
       def uncountable(*words)
-        @uncountables += words.flatten.map(&:downcase)
+        @uncountables.add(words)
       end
 
       # Specifies a humanized form of a string by a regular expression rule or
@@ -185,7 +216,7 @@ module ActiveSupport
       def clear(scope = :all)
         case scope
           when :all
-            @plurals, @singulars, @uncountables, @humans = [], [], [], []
+            @plurals, @singulars, @uncountables, @humans = [], [], Uncountables.new, []
           else
             instance_variable_set "@#{scope}", []
         end
diff --git a/activesupport/lib/active_support/inflector/methods.rb b/activesupport/lib/active_support/inflector/methods.rb
index fe8a2ac9ba..595b0339cc 100644
--- a/activesupport/lib/active_support/inflector/methods.rb
+++ b/activesupport/lib/active_support/inflector/methods.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 require 'active_support/inflections'
 
 module ActiveSupport
@@ -68,12 +66,12 @@ module ActiveSupport
     def camelize(term, uppercase_first_letter = true)
       string = term.to_s
       if uppercase_first_letter
-        string = string.sub(/^[a-z\d]*/) { inflections.acronyms[$&] || $&.capitalize }
+        string = string.sub(/^[a-z\d]*/) { |match| inflections.acronyms[match] || match.capitalize }
       else
-        string = string.sub(/^(?:#{inflections.acronym_regex}(?=\b|[A-Z_])|\w)/) { $&.downcase }
+        string = string.sub(/^(?:#{inflections.acronym_regex}(?=\b|[A-Z_])|\w)/) { |match| match.downcase }
       end
       string.gsub!(/(?:_|(\/))([a-z\d]*)/i) { "#{$1}#{inflections.acronyms[$2] || $2.capitalize}" }
-      string.gsub!(/\//, '::')
+      string.gsub!('/'.freeze, '::'.freeze)
       string
     end
 
@@ -90,11 +88,11 @@ module ActiveSupport
     #   camelize(underscore('SSLError'))  # => "SslError"
     def underscore(camel_cased_word)
       return camel_cased_word unless camel_cased_word =~ /[A-Z-]|::/
-      word = camel_cased_word.to_s.gsub(/::/, '/')
-      word.gsub!(/(?:(?<=([A-Za-z\d]))|\b)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1 && '_'}#{$2.downcase}" }
-      word.gsub!(/([A-Z\d]+)([A-Z][a-z])/,'\1_\2')
-      word.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
-      word.tr!("-", "_")
+      word = camel_cased_word.to_s.gsub('::'.freeze, '/'.freeze)
+      word.gsub!(/(?:(?<=([A-Za-z\d]))|\b)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1 && '_'.freeze }#{$2.downcase}" }
+      word.gsub!(/([A-Z\d]+)([A-Z][a-z])/, '\1_\2'.freeze)
+      word.gsub!(/([a-z\d])([A-Z])/, '\1_\2'.freeze)
+      word.tr!("-".freeze, "_".freeze)
       word.downcase!
       word
     end
@@ -127,9 +125,9 @@ module ActiveSupport
 
       inflections.humans.each { |(rule, replacement)| break if result.sub!(rule, replacement) }
 
-      result.sub!(/\A_+/, '')
-      result.sub!(/_id\z/, '')
-      result.tr!('_', ' ')
+      result.sub!(/\A_+/, ''.freeze)
+      result.sub!(/_id\z/, ''.freeze)
+      result.tr!('_'.freeze, ' '.freeze)
 
       result.gsub!(/([a-z\d]*)/i) do |match|
         "#{inflections.acronyms[match] || match.downcase}"
@@ -153,14 +151,14 @@ module ActiveSupport
     #   titleize('TheManWithoutAPast')       # => "The Man Without A Past"
     #   titleize('raiders_of_the_lost_ark')  # => "Raiders Of The Lost Ark"
     def titleize(word)
-      humanize(underscore(word)).gsub(/\b(?<!['’`])[a-z]/) { $&.capitalize }
+      humanize(underscore(word)).gsub(/\b(?<!['’`])[a-z]/) { |match| match.capitalize }
     end
 
     # Creates the name of a table like Rails does for models to table names.
     # This method uses the #pluralize method on the last word in the string.
     #
     #   tableize('RawScaledScorer') # => "raw_scaled_scorers"
-    #   tableize('egg_and_ham')     # => "egg_and_hams"
+    #   tableize('ham_and_egg')     # => "ham_and_eggs"
     #   tableize('fancyCategory')   # => "fancy_categories"
     def tableize(class_name)
       pluralize(underscore(class_name))
@@ -170,7 +168,7 @@ module ActiveSupport
     # names to models. Note that this returns a string and not a Class (To
     # convert to an actual class follow +classify+ with #constantize).
     #
-    #   classify('egg_and_hams') # => "EggAndHam"
+    #   classify('ham_and_eggs') # => "HamAndEgg"
     #   classify('posts')        # => "Post"
     #
     # Singular names are not handled correctly:
@@ -178,14 +176,14 @@ module ActiveSupport
     #   classify('calculus')     # => "Calculu"
     def classify(table_name)
       # strip out any leading schema name
-      camelize(singularize(table_name.to_s.sub(/.*\./, '')))
+      camelize(singularize(table_name.to_s.sub(/.*\./, ''.freeze)))
     end
 
     # Replaces underscores with dashes in the string.
     #
     #   dasherize('puni_puni') # => "puni-puni"
     def dasherize(underscored_word)
-      underscored_word.tr('_', '-')
+      underscored_word.tr('_'.freeze, '-'.freeze)
     end
 
     # Removes the module part from the expression in the string.
@@ -231,8 +229,8 @@ module ActiveSupport
 
     # Tries to find a constant with the name specified in the argument string.
     #
-    #   'Module'.constantize     # => Module
-    #   'Test::Unit'.constantize # => Test::Unit
+    #   'Module'.constantize   # => Module
+    #   'Foo::Bar'.constantize # => Foo::Bar
     #
     # The name is assumed to be the one of a top-level constant, no matter
     # whether it starts with "::" or not. No lexical context is taken into
@@ -248,7 +246,7 @@ module ActiveSupport
     # NameError is raised when the name is not in CamelCase or the constant is
     # unknown.
     def constantize(camel_cased_word)
-      names = camel_cased_word.split('::')
+      names = camel_cased_word.split('::'.freeze)
 
       # Trigger a built-in NameError exception including the ill-formed constant in the message.
       Object.const_get(camel_cased_word) if names.empty?
@@ -280,8 +278,8 @@ module ActiveSupport
 
     # Tries to find a constant with the name specified in the argument string.
     #
-    #   safe_constantize('Module')     # => Module
-    #   safe_constantize('Test::Unit') # => Test::Unit
+    #   safe_constantize('Module')   # => Module
+    #   safe_constantize('Foo::Bar') # => Foo::Bar
     #
     # The name is assumed to be the one of a top-level constant, no matter
     # whether it starts with "::" or not. No lexical context is taken into
@@ -354,7 +352,7 @@ module ActiveSupport
     #   const_regexp("Foo::Bar::Baz") # => "Foo(::Bar(::Baz)?)?"
     #   const_regexp("::")            # => "::"
     def const_regexp(camel_cased_word) #:nodoc:
-      parts = camel_cased_word.split("::")
+      parts = camel_cased_word.split("::".freeze)
 
       return Regexp.escape(camel_cased_word) if parts.blank?
 
@@ -372,7 +370,7 @@ module ActiveSupport
     def apply_inflections(word, rules)
       result = word.to_s.dup
 
-      if word.empty? || inflections.uncountables.include?(result.downcase[/\b\w+\Z/])
+      if word.empty? || inflections.uncountables.uncountable?(result)
         result
       else
         rules.each { |(rule, replacement)| break if result.sub!(rule, replacement) }
diff --git a/activesupport/lib/active_support/inflector/transliterate.rb b/activesupport/lib/active_support/inflector/transliterate.rb
index edea142e82..103207fb63 100644
--- a/activesupport/lib/active_support/inflector/transliterate.rb
+++ b/activesupport/lib/active_support/inflector/transliterate.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'active_support/core_ext/string/multibyte'
 require 'active_support/i18n'
 
@@ -58,7 +57,7 @@ module ActiveSupport
     #   I18n.locale = :de
     #   transliterate('Jürgen')
     #   # => "Juergen"
-    def transliterate(string, replacement = "?")
+    def transliterate(string, replacement = "?".freeze)
       I18n.transliterate(ActiveSupport::Multibyte::Unicode.normalize(
         ActiveSupport::Multibyte::Unicode.tidy_bytes(string), :c),
           :replacement => replacement)
@@ -70,18 +69,29 @@ module ActiveSupport
     #   parameterize("Donald E. Knuth") # => "donald-e-knuth"
     #   parameterize("^trés|Jolie-- ")  # => "tres-jolie"
     def parameterize(string, sep = '-')
-      # replace accented chars with their ascii equivalents
+      # Replace accented chars with their ASCII equivalents.
       parameterized_string = transliterate(string)
-      # Turn unwanted chars into the separator
+
+      # Turn unwanted chars into the separator.
       parameterized_string.gsub!(/[^a-z0-9\-_]+/i, sep)
+
       unless sep.nil? || sep.empty?
-        re_sep = Regexp.escape(sep)
+        if sep == "-".freeze
+          re_duplicate_separator        = /-{2,}/
+          re_leading_trailing_separator = /^-|-$/i
+        else
+          re_sep = Regexp.escape(sep)
+          re_duplicate_separator        = /#{re_sep}{2,}/
+          re_leading_trailing_separator = /^#{re_sep}|#{re_sep}$/i
+        end
         # No more than one of the separator in a row.
-        parameterized_string.gsub!(/#{re_sep}{2,}/, sep)
+        parameterized_string.gsub!(re_duplicate_separator, sep)
         # Remove leading/trailing separator.
-        parameterized_string.gsub!(/^#{re_sep}|#{re_sep}$/i, '')
+        parameterized_string.gsub!(re_leading_trailing_separator, ''.freeze)
       end
-      parameterized_string.downcase
+
+      parameterized_string.downcase!
+      parameterized_string
     end
   end
 end
diff --git a/activesupport/lib/active_support/json/decoding.rb b/activesupport/lib/active_support/json/decoding.rb
index 35548f3f56..2932954f03 100644
--- a/activesupport/lib/active_support/json/decoding.rb
+++ b/activesupport/lib/active_support/json/decoding.rb
@@ -9,20 +9,14 @@ module ActiveSupport
   module JSON
     # matches YAML-formatted dates
     DATE_REGEX = /^(?:\d{4}-\d{2}-\d{2}|\d{4}-\d{1,2}-\d{1,2}[T \t]+\d{1,2}:\d{2}:\d{2}(\.[0-9]*)?(([ \t]*)Z|[-+]\d{2}?(:\d{2})?))$/
-    
+
     class << self
       # Parses a JSON string (JavaScript Object Notation) into a hash.
       # See http://www.json.org for more info.
       #
       #   ActiveSupport::JSON.decode("{\"team\":\"rails\",\"players\":\"36\"}")
       #   => {"team" => "rails", "players" => "36"}
-      def decode(json, options = {})
-        if options.present?
-          raise ArgumentError, "In Rails 4.1, ActiveSupport::JSON.decode no longer " \
-            "accepts an options hash for MultiJSON. MultiJSON reached its end of life " \
-            "and has been removed."
-        end
-
+      def decode(json)
         data = ::JSON.parse(json, quirks_mode: true)
 
         if ActiveSupport.parse_json_times
diff --git a/activesupport/lib/active_support/json/encoding.rb b/activesupport/lib/active_support/json/encoding.rb
index 48f4967892..031c5e9339 100644
--- a/activesupport/lib/active_support/json/encoding.rb
+++ b/activesupport/lib/active_support/json/encoding.rb
@@ -57,6 +57,10 @@ module ActiveSupport
                 super.gsub ESCAPE_REGEX_WITHOUT_HTML_ENTITIES, ESCAPED_CHARS
               end
             end
+
+            def to_s
+              self
+            end
           end
 
           # Mark these as private so we don't leak encoding-specific constructs
diff --git a/activesupport/lib/active_support/key_generator.rb b/activesupport/lib/active_support/key_generator.rb
index 51d2da3a79..6bc3db6ec6 100644
--- a/activesupport/lib/active_support/key_generator.rb
+++ b/activesupport/lib/active_support/key_generator.rb
@@ -1,4 +1,4 @@
-require 'thread_safe'
+require 'concurrent'
 require 'openssl'
 
 module ActiveSupport
@@ -28,7 +28,7 @@ module ActiveSupport
   class CachingKeyGenerator
     def initialize(key_generator)
       @key_generator = key_generator
-      @cache_keys = ThreadSafe::Cache.new
+      @cache_keys = Concurrent::Map.new
     end
 
     # Returns a derived key suitable for use.  The default key_size is chosen
diff --git a/activesupport/lib/active_support/log_subscriber.rb b/activesupport/lib/active_support/log_subscriber.rb
index e95dc5a866..e782cd2d4b 100644
--- a/activesupport/lib/active_support/log_subscriber.rb
+++ b/activesupport/lib/active_support/log_subscriber.rb
@@ -95,7 +95,7 @@ module ActiveSupport
       METHOD
     end
 
-    # Set color by using a string or one of the defined constants. If a third
+    # Set color by using a symbol or one of the defined constants. If a third
     # option is set to +true+, it also adds bold to the string. This is based
     # on the Highline implementation and will automatically append CLEAR to the
     # end of the returned String.
diff --git a/activesupport/lib/active_support/log_subscriber/test_helper.rb b/activesupport/lib/active_support/log_subscriber/test_helper.rb
index 75f353f62c..cbc20c103d 100644
--- a/activesupport/lib/active_support/log_subscriber/test_helper.rb
+++ b/activesupport/lib/active_support/log_subscriber/test_helper.rb
@@ -11,6 +11,7 @@ module ActiveSupport
     #     include ActiveSupport::LogSubscriber::TestHelper
     #
     #     def setup
+    #       super
     #       ActiveRecord::LogSubscriber.attach_to(:active_record)
     #     end
     #
@@ -33,7 +34,7 @@ module ActiveSupport
     # you can collect them doing @logger.logged(level), where level is the level
     # used in logging, like info, debug, warn and so on.
     module TestHelper
-      def setup
+      def setup # :nodoc:
         @logger   = MockLogger.new
         @notifier = ActiveSupport::Notifications::Fanout.new
 
@@ -44,7 +45,7 @@ module ActiveSupport
         ActiveSupport::Notifications.notifier = @notifier
       end
 
-      def teardown
+      def teardown # :nodoc:
         set_logger(nil)
         ActiveSupport::Notifications.notifier = @old_notifier
       end
diff --git a/activesupport/lib/active_support/message_encryptor.rb b/activesupport/lib/active_support/message_encryptor.rb
index 92ab6fe648..c82a13511e 100644
--- a/activesupport/lib/active_support/message_encryptor.rb
+++ b/activesupport/lib/active_support/message_encryptor.rb
@@ -82,7 +82,7 @@ module ActiveSupport
 
     def _decrypt(encrypted_message)
       cipher = new_cipher
-      encrypted_data, iv = encrypted_message.split("--").map {|v| ::Base64.strict_decode64(v)}
+      encrypted_data, iv = encrypted_message.split("--".freeze).map {|v| ::Base64.strict_decode64(v)}
 
       cipher.decrypt
       cipher.key = @secret
diff --git a/activesupport/lib/active_support/message_verifier.rb b/activesupport/lib/active_support/message_verifier.rb
index eee9bbaead..64c5232cf4 100644
--- a/activesupport/lib/active_support/message_verifier.rb
+++ b/activesupport/lib/active_support/message_verifier.rb
@@ -44,9 +44,9 @@ module ActiveSupport
     #   tampered_message = signed_message.chop # editing the message invalidates the signature
     #   verifier.valid_message?(tampered_message) # => false
     def valid_message?(signed_message)
-      return if signed_message.blank?
+      return if signed_message.nil? || !signed_message.valid_encoding? || signed_message.blank?
 
-      data, digest = signed_message.split("--")
+      data, digest = signed_message.split("--".freeze)
       data.present? && digest.present? && ActiveSupport::SecurityUtils.secure_compare(digest, generate_digest(data))
     end
 
@@ -74,7 +74,7 @@ module ActiveSupport
     def verified(signed_message)
       if valid_message?(signed_message)
         begin
-          data = signed_message.split("--")[0]
+          data = signed_message.split("--".freeze)[0]
           @serializer.load(decode(data))
         rescue ArgumentError => argument_error
           return if argument_error.message =~ %r{invalid base64}
diff --git a/activesupport/lib/active_support/multibyte/chars.rb b/activesupport/lib/active_support/multibyte/chars.rb
index 3c0cf9f137..707cf200b5 100644
--- a/activesupport/lib/active_support/multibyte/chars.rb
+++ b/activesupport/lib/active_support/multibyte/chars.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'active_support/json'
 require 'active_support/core_ext/string/access'
 require 'active_support/core_ext/string/behavior'
@@ -86,10 +85,20 @@ module ActiveSupport #:nodoc:
         @wrapped_string.split(*args).map { |i| self.class.new(i) }
       end
 
-      # Works like like <tt>String#slice!</tt>, but returns an instance of
-      # Chars, or nil if the string was not modified.
+      # Works like <tt>String#slice!</tt>, but returns an instance of
+      # Chars, or nil if the string was not modified. The string will not be
+      # modified if the range given is out of bounds
+      #
+      #   string = 'Welcome'
+      #   string.mb_chars.slice!(3)    # => #<ActiveSupport::Multibyte::Chars:0x000000038109b8 @wrapped_string="c">
+      #   string # => 'Welome'
+      #   string.mb_chars.slice!(0..3) # => #<ActiveSupport::Multibyte::Chars:0x00000002eb80a0 @wrapped_string="Welo">
+      #   string # => 'me'
       def slice!(*args)
-        chars(@wrapped_string.slice!(*args))
+        string_sliced = @wrapped_string.slice!(*args)
+        if string_sliced
+          chars(string_sliced)
+        end
       end
 
       # Reverses all characters in the string.
diff --git a/activesupport/lib/active_support/multibyte/unicode.rb b/activesupport/lib/active_support/multibyte/unicode.rb
index 35efebc65f..586002b03b 100644
--- a/activesupport/lib/active_support/multibyte/unicode.rb
+++ b/activesupport/lib/active_support/multibyte/unicode.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 module ActiveSupport
   module Multibyte
     module Unicode
@@ -11,7 +10,7 @@ module ActiveSupport
       NORMALIZATION_FORMS = [:c, :kc, :d, :kd]
 
       # The Unicode version that is supported by the implementation
-      UNICODE_VERSION = '7.0.0'
+      UNICODE_VERSION = '8.0.0'
 
       # The default normalization used for operations that require
       # normalization. It can be set to any of the normalizations
@@ -58,7 +57,7 @@ module ActiveSupport
       # Returns a regular expression pattern that matches the passed Unicode
       # codepoints.
       def self.codepoints_to_pattern(array_of_codepoints) #:nodoc:
-        array_of_codepoints.collect{ |e| [e].pack 'U*' }.join('|')
+        array_of_codepoints.collect{ |e| [e].pack 'U*'.freeze }.join('|'.freeze)
       end
       TRAILERS_PAT = /(#{codepoints_to_pattern(LEADERS_AND_TRAILERS)})+\Z/u
       LEADERS_PAT = /\A(#{codepoints_to_pattern(LEADERS_AND_TRAILERS)})+/u
@@ -257,7 +256,7 @@ module ActiveSupport
       # * <tt>string</tt> - The string to perform normalization on.
       # * <tt>form</tt> - The form you want to normalize in. Should be one of
       #   the following: <tt>:c</tt>, <tt>:kc</tt>, <tt>:d</tt>, or <tt>:kd</tt>.
-      #   Default is ActiveSupport::Multibyte.default_normalization_form.
+      #   Default is ActiveSupport::Multibyte::Unicode.default_normalization_form.
       def normalize(string, form=nil)
         form ||= @default_normalization_form
         # See http://www.unicode.org/reports/tr15, Table 1
@@ -273,7 +272,7 @@ module ActiveSupport
             compose(reorder_characters(decompose(:compatibility, codepoints)))
           else
             raise ArgumentError, "#{form} is not a valid normalization variant", caller
-        end.pack('U*')
+        end.pack('U*'.freeze)
       end
 
       def downcase(string)
@@ -338,7 +337,7 @@ module ActiveSupport
           end
 
           # Redefine the === method so we can write shorter rules for grapheme cluster breaks
-          @boundary.each do |k,_|
+          @boundary.each_key do |k|
             @boundary[k].instance_eval do
               def ===(other)
                 detect { |i| i === other } ? true : false
diff --git a/activesupport/lib/active_support/notifications.rb b/activesupport/lib/active_support/notifications.rb
index b9f8e1ab2c..823d68e507 100644
--- a/activesupport/lib/active_support/notifications.rb
+++ b/activesupport/lib/active_support/notifications.rb
@@ -69,8 +69,8 @@ module ActiveSupport
   # is able to take the arguments as they come and provide an object-oriented
   # interface to that data.
   #
-  # It is also possible to pass an object as the second parameter passed to the
-  # <tt>subscribe</tt> method instead of a block:
+  # It is also possible to pass an object which responds to <tt>call</tt> method
+  # as the second parameter to the <tt>subscribe</tt> method instead of a block:
   #
   #   module ActionController
   #     class PageRequest
diff --git a/activesupport/lib/active_support/notifications/fanout.rb b/activesupport/lib/active_support/notifications/fanout.rb
index 6bf8c7d5de..71354dd15f 100644
--- a/activesupport/lib/active_support/notifications/fanout.rb
+++ b/activesupport/lib/active_support/notifications/fanout.rb
@@ -1,5 +1,5 @@
 require 'mutex_m'
-require 'thread_safe'
+require 'concurrent'
 
 module ActiveSupport
   module Notifications
@@ -12,7 +12,7 @@ module ActiveSupport
 
       def initialize
         @subscribers = []
-        @listeners_for = ThreadSafe::Cache.new
+        @listeners_for = Concurrent::Map.new
         super
       end
 
@@ -51,7 +51,7 @@ module ActiveSupport
       end
 
       def listeners_for(name)
-        # this is correctly done double-checked locking (ThreadSafe::Cache's lookups have volatile semantics)
+        # this is correctly done double-checked locking (Concurrent::Map's lookups have volatile semantics)
         @listeners_for[name] || synchronize do
           # use synchronisation when accessing @subscribers
           @listeners_for[name] ||= @subscribers.select { |s| s.subscribed_to?(name) }
@@ -111,7 +111,7 @@ module ActiveSupport
           end
         end
 
-        class Timed < Evented
+        class Timed < Evented # :nodoc:
           def publish(name, *args)
             @delegate.call name, *args
           end
diff --git a/activesupport/lib/active_support/number_helper.rb b/activesupport/lib/active_support/number_helper.rb
index 34439ee8be..504f96961a 100644
--- a/activesupport/lib/active_support/number_helper.rb
+++ b/activesupport/lib/active_support/number_helper.rb
@@ -94,9 +94,9 @@ module ActiveSupport
     # * <tt>:locale</tt> - Sets the locale to be used for formatting
     #   (defaults to current locale).
     # * <tt>:precision</tt> - Sets the precision of the number
-    #   (defaults to 3).
-    # * <tt>:significant</tt> - If +true+, precision will be the #
-    #   of significant_digits. If +false+, the # of fractional
+    #   (defaults to 3). Keeps the number's precision if nil.
+    # * <tt>:significant</tt> - If +true+, precision will be the number
+    #   of significant_digits. If +false+, the number of fractional
     #   digits (defaults to +false+).
     # * <tt>:separator</tt> - Sets the separator between the
     #   fractional and integer digits (defaults to ".").
@@ -116,8 +116,9 @@ module ActiveSupport
     #   number_to_percentage(1000, delimiter: '.', separator: ',') # => 1.000,000%
     #   number_to_percentage(302.24398923423, precision: 5)        # => 302.24399%
     #   number_to_percentage(1000, locale: :fr)                    # => 1 000,000%
+    #   number_to_percentage:(1000, precision: nil)                # => 1000%
     #   number_to_percentage('98a')                                # => 98a%
-    #   number_to_percentage(100, format: '%n  %')                 # => 100  %
+    #   number_to_percentage(100, format: '%n  %')                 # => 100.000  %
     def number_to_percentage(number, options = {})
       NumberToPercentageConverter.convert(number, options)
     end
@@ -134,6 +135,9 @@ module ActiveSupport
     #   to ",").
     # * <tt>:separator</tt> - Sets the separator between the
     #   fractional and integer digits (defaults to ".").
+    # * <tt>:delimiter_pattern</tt> - Sets a custom regular expression used for
+    #   deriving the placement of delimiter. Helpful when using currency formats
+    #   like INR.
     #
     # ==== Examples
     #
@@ -146,7 +150,10 @@ module ActiveSupport
     #   number_to_delimited(12345678.05, locale: :fr)    # => 12 345 678,05
     #   number_to_delimited('112a')                      # => 112a
     #   number_to_delimited(98765432.98, delimiter: ' ', separator: ',')
-    #   # => 98 765 432,98
+    #                                                    # => 98 765 432,98
+    #   number_to_delimited("123456.78",
+    #     delimiter_pattern: /(\d+?)(?=(\d\d)+(\d)(?!\d))/)
+    #                                                    # => 1,23,456.78
     def number_to_delimited(number, options = {})
       NumberToDelimitedConverter.convert(number, options)
     end
@@ -161,9 +168,9 @@ module ActiveSupport
     # * <tt>:locale</tt> - Sets the locale to be used for formatting
     #   (defaults to current locale).
     # * <tt>:precision</tt> - Sets the precision of the number
-    #   (defaults to 3).
-    # * <tt>:significant</tt> - If +true+, precision will be the #
-    #   of significant_digits. If +false+, the # of fractional
+    #   (defaults to 3). Keeps the number's precision if nil.
+    # * <tt>:significant</tt> - If +true+, precision will be the number
+    #   of significant_digits. If +false+, the number of fractional
     #   digits (defaults to +false+).
     # * <tt>:separator</tt> - Sets the separator between the
     #   fractional and integer digits (defaults to ".").
@@ -182,6 +189,7 @@ module ActiveSupport
     #   number_to_rounded(111.2345, significant: true)               # => 111
     #   number_to_rounded(111.2345, precision: 1, significant: true) # => 100
     #   number_to_rounded(13, precision: 5, significant: true)       # => 13.000
+    #   number_to_rounded(13, precision: nil)                        # => 13
     #   number_to_rounded(111.234, locale: :fr)                      # => 111,234
     #
     #   number_to_rounded(13, precision: 5, significant: true, strip_insignificant_zeros: true)
@@ -208,8 +216,8 @@ module ActiveSupport
     #   (defaults to current locale).
     # * <tt>:precision</tt> - Sets the precision of the number
     #   (defaults to 3).
-    # * <tt>:significant</tt> - If +true+, precision will be the #
-    #   of significant_digits. If +false+, the # of fractional
+    # * <tt>:significant</tt> - If +true+, precision will be the number
+    #   of significant_digits. If +false+, the number of fractional
     #   digits (defaults to +true+)
     # * <tt>:separator</tt> - Sets the separator between the
     #   fractional and integer digits (defaults to ".").
@@ -218,8 +226,6 @@ module ActiveSupport
     # * <tt>:strip_insignificant_zeros</tt> - If +true+ removes
     #   insignificant zeros after the decimal separator (defaults to
     #   +true+)
-    # * <tt>:prefix</tt> - If +:si+ formats the number using the SI
-    #   prefix (defaults to :binary)
     #
     # ==== Examples
     #
@@ -258,8 +264,8 @@ module ActiveSupport
     #   (defaults to current locale).
     # * <tt>:precision</tt> - Sets the precision of the number
     #   (defaults to 3).
-    # * <tt>:significant</tt> - If +true+, precision will be the #
-    #   of significant_digits. If +false+, the # of fractional
+    # * <tt>:significant</tt> - If +true+, precision will be the number
+    #   of significant_digits. If +false+, the number of fractional
     #   digits (defaults to +true+)
     # * <tt>:separator</tt> - Sets the separator between the
     #   fractional and integer digits (defaults to ".").
diff --git a/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb b/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
index fb5adb574a..7986eb50f0 100644
--- a/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
@@ -13,7 +13,7 @@ module ActiveSupport
         end
 
         rounded_number = NumberToRoundedConverter.convert(number, options)
-        format.gsub(/%n/, rounded_number).gsub(/%u/, options[:unit])
+        format.gsub('%n'.freeze, rounded_number).gsub('%u'.freeze, options[:unit])
       end
 
       private
@@ -23,20 +23,20 @@ module ActiveSupport
         end
 
         def absolute_value(number)
-          number.respond_to?("abs") ? number.abs : number.sub(/\A-/, '')
+          number.respond_to?(:abs) ? number.abs : number.sub(/\A-/, '')
         end
 
         def options
           @options ||= begin
             defaults = default_format_options.merge(i18n_opts)
-            # Override negative format if format options is given
+            # Override negative format if format options are given
             defaults[:negative_format] = "-#{opts[:format]}" if opts[:format]
             defaults.merge!(opts)
           end
         end
 
         def i18n_opts
-          # Set International negative format if not exists
+          # Set International negative format if it does not exist
           i18n = i18n_format_options
           i18n[:negative_format] ||= "-#{i18n[:format]}" if i18n[:format]
           i18n
diff --git a/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb b/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb
index d85cc086d7..45ae8f1a93 100644
--- a/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb
@@ -3,7 +3,7 @@ module ActiveSupport
     class NumberToDelimitedConverter < NumberConverter #:nodoc:
       self.validate_float = true
 
-      DELIMITED_REGEX = /(\d)(?=(\d\d\d)+(?!\d))/
+      DEFAULT_DELIMITER_REGEX = /(\d)(?=(\d\d\d)+(?!\d))/
 
       def convert
         parts.join(options[:separator])
@@ -13,11 +13,16 @@ module ActiveSupport
 
         def parts
           left, right = number.to_s.split('.')
-          left.gsub!(DELIMITED_REGEX) do |digit_to_delimit|
+          left.gsub!(delimiter_pattern) do |digit_to_delimit|
             "#{digit_to_delimit}#{options[:delimiter]}"
           end
           [left, right].compact
         end
+
+        def delimiter_pattern
+          options.fetch(:delimiter_pattern, DEFAULT_DELIMITER_REGEX)
+        end
+
     end
   end
 end
diff --git a/activesupport/lib/active_support/number_helper/number_to_human_converter.rb b/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
index 6940beb318..7a1f8171c0 100644
--- a/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
@@ -20,10 +20,12 @@ module ActiveSupport
         exponent = calculate_exponent(units)
         @number = number / (10 ** exponent)
 
+        until (rounded_number = NumberToRoundedConverter.convert(number, options)) != NumberToRoundedConverter.convert(1000, options)
+          @number = number / 1000.0
+          exponent += 3
+        end
         unit = determine_unit(units, exponent)
-
-        rounded_number = NumberToRoundedConverter.convert(number, options)
-        format.gsub(/%n/, rounded_number).gsub(/%u/, unit).strip
+        format.gsub('%n'.freeze, rounded_number).gsub('%u'.freeze, unit).strip
       end
 
       private
diff --git a/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb b/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
index 78d2c9ae6e..a4a8690bcd 100644
--- a/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
@@ -7,6 +7,10 @@ module ActiveSupport
       self.validate_float = true
 
       def convert
+        if opts.key?(:prefix)
+          ActiveSupport::Deprecation.warn('The :prefix option of `number_to_human_size` is deprecated and will be removed in Rails 5.1 with no replacement.')
+        end
+
         @number = Float(number)
 
         # for backwards compatibility with those that didn't add strip_insignificant_zeros to their locale files
@@ -20,7 +24,7 @@ module ActiveSupport
           human_size = number / (base ** exponent)
           number_to_format = NumberToRoundedConverter.convert(human_size, options)
         end
-        conversion_format.gsub(/%n/, number_to_format).gsub(/%u/, unit)
+        conversion_format.gsub('%n'.freeze, number_to_format).gsub('%u'.freeze, unit)
       end
 
       private
diff --git a/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb b/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
index 1af294a03e..4c04d40c19 100644
--- a/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
@@ -5,7 +5,7 @@ module ActiveSupport
 
       def convert
         rounded_number = NumberToRoundedConverter.convert(number, options)
-        options[:format].gsub(/%n/, rounded_number)
+        options[:format].gsub('%n'.freeze, rounded_number)
       end
     end
   end
diff --git a/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb b/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb
index dcf9a567e8..981c562551 100644
--- a/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb
@@ -6,36 +6,39 @@ module ActiveSupport
 
       def convert
         precision = options.delete :precision
-        significant = options.delete :significant
 
-        case number
-        when Float, String
-          @number = BigDecimal(number.to_s)
-        when Rational
-          @number = BigDecimal(number, digit_count(number.to_i) + precision)
-        else
-          @number = number.to_d
-        end
-
-        if significant && precision > 0
-          digits, rounded_number = digits_and_rounded_number(precision)
-          precision -= digits
-          precision = 0 if precision < 0 # don't let it be negative
-        else
-          rounded_number = number.round(precision)
-          rounded_number = rounded_number.to_i if precision == 0
-          rounded_number = rounded_number.abs if rounded_number.zero? # prevent showing negative zeros
-        end
+        if precision
+          case number
+          when Float, String
+            @number = BigDecimal(number.to_s)
+          when Rational
+            @number = BigDecimal(number, digit_count(number.to_i) + precision)
+          else
+            @number = number.to_d
+          end
 
-        formatted_string =
-          if BigDecimal === rounded_number && rounded_number.finite?
-            s = rounded_number.to_s('F') + '0'*precision
-            a, b = s.split('.', 2)
-            a + '.' + b[0, precision]
+          if options.delete(:significant) && precision > 0
+            digits, rounded_number = digits_and_rounded_number(precision)
+            precision -= digits
+            precision = 0 if precision < 0 # don't let it be negative
           else
-            "%00.#{precision}f" % rounded_number
+            rounded_number = number.round(precision)
+            rounded_number = rounded_number.to_i if precision == 0 && rounded_number.finite?
+            rounded_number = rounded_number.abs if rounded_number.zero? # prevent showing negative zeros
           end
 
+          formatted_string =
+            if BigDecimal === rounded_number && rounded_number.finite?
+              s = rounded_number.to_s('F') + '0'*precision
+              a, b = s.split('.', 2)
+              a + '.' + b[0, precision]
+            else
+              "%00.#{precision}f" % rounded_number
+            end
+        else
+          formatted_string = number
+        end
+
         delimited_number = NumberToDelimitedConverter.convert(formatted_string, options)
         format_number(delimited_number)
       end
diff --git a/activesupport/lib/active_support/ordered_options.rb b/activesupport/lib/active_support/ordered_options.rb
index a33e2c58a9..45864990ce 100644
--- a/activesupport/lib/active_support/ordered_options.rb
+++ b/activesupport/lib/active_support/ordered_options.rb
@@ -6,6 +6,7 @@ module ActiveSupport
   #   h[:girl] = 'Mary'
   #   h[:boy]  # => 'John'
   #   h[:girl] # => 'Mary'
+  #   h[:dog]  # => nil
   #
   # Using +OrderedOptions+, the above code could be reduced to:
   #
@@ -14,6 +15,13 @@ module ActiveSupport
   #   h.girl = 'Mary'
   #   h.boy  # => 'John'
   #   h.girl # => 'Mary'
+  #   h.dog  # => nil
+  #
+  # To raise an exception when the value is blank, append a
+  # bang to the key name, like:
+  #
+  #   h.dog! # => raises KeyError
+  #
   class OrderedOptions < Hash
     alias_method :_get, :[] # preserve the original #[] method
     protected :_get # make it protected
@@ -31,7 +39,13 @@ module ActiveSupport
       if name_string.chomp!('=')
         self[name_string] = args.first
       else
-        self[name]
+        bangs = name_string.chomp!('!')
+
+        if bangs
+          fetch(name_string.to_sym).presence || raise(KeyError.new("#{name_string} is blank."))
+        else
+          self[name_string]
+        end
       end
     end
 
diff --git a/activesupport/lib/active_support/per_thread_registry.rb b/activesupport/lib/active_support/per_thread_registry.rb
index ca2e4d5625..506dd950cb 100644
--- a/activesupport/lib/active_support/per_thread_registry.rb
+++ b/activesupport/lib/active_support/per_thread_registry.rb
@@ -43,9 +43,9 @@ module ActiveSupport
     protected
       def method_missing(name, *args, &block) # :nodoc:
         # Caches the method definition as a singleton method of the receiver.
-        define_singleton_method(name) do |*a, &b|
-          instance.public_send(name, *a, &b)
-        end
+        #
+        # By letting #delegate handle it, we avoid an enclosure that'll capture args.
+        singleton_class.delegate name, to: :instance
 
         send(name, *args, &block)
       end
diff --git a/activesupport/lib/active_support/rails.rb b/activesupport/lib/active_support/rails.rb
index b05c3ff126..c8e3a4bf53 100644
--- a/activesupport/lib/active_support/rails.rb
+++ b/activesupport/lib/active_support/rails.rb
@@ -1,8 +1,8 @@
 # This is private interface.
 #
 # Rails components cherry pick from Active Support as needed, but there are a
-# few features that are used for sure some way or another and it is not worth
-# to put individual requires absolutely everywhere. Think blank? for example.
+# few features that are used for sure in some way or another and it is not worth
+# putting individual requires absolutely everywhere. Think blank? for example.
 #
 # This file is loaded by every Rails component except Active Support itself,
 # but it does not belong to the Rails public interface. It is internal to
diff --git a/activesupport/lib/active_support/railtie.rb b/activesupport/lib/active_support/railtie.rb
index 6eba24b569..845788b669 100644
--- a/activesupport/lib/active_support/railtie.rb
+++ b/activesupport/lib/active_support/railtie.rb
@@ -13,22 +13,20 @@ module ActiveSupport
       end
     end
 
-    initializer "active_support.halt_callback_chains_on_return_false", after: :load_config_initializers do |app|
-      if app.config.active_support.key? :halt_callback_chains_on_return_false
-        ActiveSupport::Callbacks::CallbackChain.halt_and_display_warning_on_return_false = \
-          app.config.active_support.halt_callback_chains_on_return_false
-      end
-    end
-
     # Sets the default value for Time.zone
     # If assigned value cannot be matched to a TimeZone, an exception will be raised.
     initializer "active_support.initialize_time_zone" do |app|
+      begin
+        TZInfo::DataSource.get
+      rescue TZInfo::DataSourceNotFound => e
+        raise e.exception "tzinfo-data is not present. Please add gem 'tzinfo-data' to your Gemfile and run bundle install"
+      end
       require 'active_support/core_ext/time/zones'
       zone_default = Time.find_zone!(app.config.time_zone)
 
       unless zone_default
         raise 'Value assigned to config.time_zone not recognized. ' \
-          'Run "rake -D time" for a list of tasks for finding appropriate time zone names.'
+          'Run "rake time:zones:all" for a time zone names list.'
       end
 
       Time.zone_default = zone_default
diff --git a/activesupport/lib/active_support/rescuable.rb b/activesupport/lib/active_support/rescuable.rb
index 1a02acd5b1..fcf5553061 100644
--- a/activesupport/lib/active_support/rescuable.rb
+++ b/activesupport/lib/active_support/rescuable.rb
@@ -68,7 +68,7 @@ module ActiveSupport
             raise ArgumentError, "#{klass} is neither an Exception nor a String"
           end
 
-          # put the new handler at the end because the list is read in reverse
+          # Put the new handler at the end because the list is read in reverse.
           self.rescue_handlers += [[key, options[:with]]]
         end
       end
@@ -100,7 +100,7 @@ module ActiveSupport
         # a string, otherwise a NameError will be raised by the interpreter
         # itself when rescue_from CONSTANT is executed.
         klass = self.class.const_get(klass_name) rescue nil
-        klass ||= klass_name.constantize rescue nil
+        klass ||= (klass_name.constantize rescue nil)
         klass === exception if klass
       end
 
diff --git a/activesupport/lib/active_support/string_inquirer.rb b/activesupport/lib/active_support/string_inquirer.rb
index 45271c9163..bc673150d0 100644
--- a/activesupport/lib/active_support/string_inquirer.rb
+++ b/activesupport/lib/active_support/string_inquirer.rb
@@ -1,7 +1,7 @@
 module ActiveSupport
   # Wrapping a string in this class gives you a prettier way to test
   # for equality. The value returned by <tt>Rails.env</tt> is wrapped
-  # in a StringInquirer object so instead of calling this:
+  # in a StringInquirer object, so instead of calling this:
   #
   #   Rails.env == 'production'
   #
diff --git a/activesupport/lib/active_support/subscriber.rb b/activesupport/lib/active_support/subscriber.rb
index 98be78b41b..1cd4b807ad 100644
--- a/activesupport/lib/active_support/subscriber.rb
+++ b/activesupport/lib/active_support/subscriber.rb
@@ -5,24 +5,19 @@ module ActiveSupport
   # ActiveSupport::Notifications. The subscriber dispatches notifications to
   # a registered object based on its given namespace.
   #
-  # An example would be Active Record subscriber responsible for collecting
+  # An example would be an Active Record subscriber responsible for collecting
   # statistics about queries:
   #
   #   module ActiveRecord
   #     class StatsSubscriber < ActiveSupport::Subscriber
+  #       attach_to :active_record
+  #
   #       def sql(event)
   #         Statsd.timing("sql.#{event.payload[:name]}", event.duration)
   #       end
   #     end
   #   end
   #
-  # And it's finally registered as:
-  #
-  #   ActiveRecord::StatsSubscriber.attach_to :active_record
-  #
-  # Since we need to know all instance methods before attaching the log
-  # subscriber, the line above should be called after your subscriber definition.
-  #
   # After configured, whenever a "sql.active_record" notification is published,
   # it will properly dispatch the event (ActiveSupport::Notifications::Event) to
   # the +sql+ method.
@@ -66,7 +61,7 @@ module ActiveSupport
 
         pattern = "#{event}.#{namespace}"
 
-        # don't add multiple subscribers (eg. if methods are redefined)
+        # Don't add multiple subscribers (eg. if methods are redefined).
         return if subscriber.patterns.include?(pattern)
 
         subscriber.patterns << pattern
@@ -96,7 +91,7 @@ module ActiveSupport
       event.end = finished
       event.payload.merge!(payload)
 
-      method = name.split('.').first
+      method = name.split('.'.freeze).first
       send(method, event)
     end
 
diff --git a/activesupport/lib/active_support/tagged_logging.rb b/activesupport/lib/active_support/tagged_logging.rb
index 9086a959aa..bcd7bf74c0 100644
--- a/activesupport/lib/active_support/tagged_logging.rb
+++ b/activesupport/lib/active_support/tagged_logging.rb
@@ -43,7 +43,7 @@ module ActiveSupport
       end
 
       def current_tags
-        # We use our object ID here to void conflicting with other instances
+        # We use our object ID here to avoid conflicting with other instances
         thread_key = @thread_key ||= "activesupport_tagged_logging_tags:#{object_id}".freeze
         Thread.current[thread_key] ||= []
       end
diff --git a/activesupport/lib/active_support/test_case.rb b/activesupport/lib/active_support/test_case.rb
index c7d6c62129..ae6f00b861 100644
--- a/activesupport/lib/active_support/test_case.rb
+++ b/activesupport/lib/active_support/test_case.rb
@@ -8,6 +8,8 @@ require 'active_support/testing/declarative'
 require 'active_support/testing/isolation'
 require 'active_support/testing/constant_lookup'
 require 'active_support/testing/time_helpers'
+require 'active_support/testing/file_fixtures'
+require 'active_support/testing/composite_filter'
 require 'active_support/core_ext/kernel/reporting'
 
 module ActiveSupport
@@ -35,17 +37,17 @@ module ActiveSupport
       # Possible values are +:random+, +:parallel+, +:alpha+, +:sorted+.
       # Defaults to +:random+.
       def test_order
-        test_order = ActiveSupport.test_order
+        ActiveSupport.test_order ||= :random
+      end
 
-        if test_order.nil?
-          test_order = :random
-          self.test_order = test_order
+      def run(reporter, options = {})
+        if options[:patterns] && options[:patterns].any? { |p| p =~ /:\d+/ }
+          options[:filter] = \
+            Testing::CompositeFilter.new(self, options[:filter], options[:patterns])
         end
 
-        test_order
+        super
       end
-
-      alias :my_tests_are_order_dependent! :i_suck_and_my_tests_are_order_dependent!
     end
 
     alias_method :method_name, :name
@@ -55,6 +57,7 @@ module ActiveSupport
     include ActiveSupport::Testing::Assertions
     include ActiveSupport::Testing::Deprecation
     include ActiveSupport::Testing::TimeHelpers
+    include ActiveSupport::Testing::FileFixtures
     extend ActiveSupport::Testing::Declarative
 
     # test/unit backwards compatibility methods
@@ -73,7 +76,7 @@ module ActiveSupport
     alias :assert_not_respond_to :refute_respond_to
     alias :assert_not_same :refute_same
 
-    # Fails if the block raises an exception.
+    # Reveals the intention that the block should not raise any exception.
     #
     #   assert_nothing_raised do
     #     ...
diff --git a/activesupport/lib/active_support/testing/assertions.rb b/activesupport/lib/active_support/testing/assertions.rb
index 8b649c193f..ae8c15d8bf 100644
--- a/activesupport/lib/active_support/testing/assertions.rb
+++ b/activesupport/lib/active_support/testing/assertions.rb
@@ -23,42 +23,42 @@ module ActiveSupport
       # result of what is evaluated in the yielded block.
       #
       #   assert_difference 'Article.count' do
-      #     post :create, article: {...}
+      #     post :create, params: { article: {...} }
       #   end
       #
       # An arbitrary expression is passed in and evaluated.
       #
-      #   assert_difference 'assigns(:article).comments(:reload).size' do
-      #     post :create, comment: {...}
+      #   assert_difference 'Article.last.comments(:reload).size' do
+      #     post :create, params: { comment: {...} }
       #   end
       #
       # An arbitrary positive or negative difference can be specified.
       # The default is <tt>1</tt>.
       #
       #   assert_difference 'Article.count', -1 do
-      #     post :delete, id: ...
+      #     post :delete, params: { id: ... }
       #   end
       #
       # An array of expressions can also be passed in and evaluated.
       #
       #   assert_difference [ 'Article.count', 'Post.count' ], 2 do
-      #     post :create, article: {...}
+      #     post :create, params: { article: {...} }
       #   end
       #
       # A lambda or a list of lambdas can be passed in and evaluated:
       #
       #   assert_difference ->{ Article.count }, 2 do
-      #     post :create, article: {...}
+      #     post :create, params: { article: {...} }
       #   end
       #
       #   assert_difference [->{ Article.count }, ->{ Post.count }], 2 do
-      #     post :create, article: {...}
+      #     post :create, params: { article: {...} }
       #   end
       #
       # An error message can be specified.
       #
       #   assert_difference 'Article.count', -1, 'An Article should be destroyed' do
-      #     post :delete, id: ...
+      #     post :delete, params: { id: ... }
       #   end
       def assert_difference(expression, difference = 1, message = nil, &block)
         expressions = Array(expression)
@@ -68,26 +68,28 @@ module ActiveSupport
         }
         before = exps.map(&:call)
 
-        yield
+        retval = yield
 
         expressions.zip(exps).each_with_index do |(code, e), i|
           error  = "#{code.inspect} didn't change by #{difference}"
           error  = "#{message}.\n#{error}" if message
           assert_equal(before[i] + difference, e.call, error)
         end
+
+        retval
       end
 
       # Assertion that the numeric result of evaluating an expression is not
       # changed before and after invoking the passed in block.
       #
       #   assert_no_difference 'Article.count' do
-      #     post :create, article: invalid_attributes
+      #     post :create, params: { article: invalid_attributes }
       #   end
       #
       # An error message can be specified.
       #
       #   assert_no_difference 'Article.count', 'An Article should not be created' do
-      #     post :create, article: invalid_attributes
+      #     post :create, params: { article: invalid_attributes }
       #   end
       def assert_no_difference(expression, message = nil, &block)
         assert_difference expression, 0, message, &block
diff --git a/activesupport/lib/active_support/testing/autorun.rb b/activesupport/lib/active_support/testing/autorun.rb
index 5aa5f46310..84c6b89340 100644
--- a/activesupport/lib/active_support/testing/autorun.rb
+++ b/activesupport/lib/active_support/testing/autorun.rb
@@ -2,4 +2,11 @@ gem 'minitest'
 
 require 'minitest'
 
-Minitest.autorun
+if Minitest.respond_to?(:run_with_rails_extension)
+  unless Minitest.run_with_rails_extension
+    Minitest.run_with_autorun = true
+    Minitest.autorun
+  end
+else
+  Minitest.autorun
+end
diff --git a/activesupport/lib/active_support/testing/composite_filter.rb b/activesupport/lib/active_support/testing/composite_filter.rb
new file mode 100644
index 0000000000..bde723e30b
--- /dev/null
+++ b/activesupport/lib/active_support/testing/composite_filter.rb
@@ -0,0 +1,54 @@
+require 'method_source'
+
+module ActiveSupport
+  module Testing
+    class CompositeFilter # :nodoc:
+      def initialize(runnable, filter, patterns)
+        @runnable = runnable
+        @filters = [ derive_regexp(filter), *derive_line_filters(patterns) ].compact
+      end
+
+      def ===(method)
+        @filters.any? { |filter| filter === method }
+      end
+
+      private
+        def derive_regexp(filter)
+          filter =~ %r%/(.*)/% ? Regexp.new($1) : filter
+        end
+
+        def derive_line_filters(patterns)
+          patterns.map do |file_and_line|
+            file, line = file_and_line.split(':')
+            Filter.new(@runnable, file, line) if file
+          end
+        end
+
+        class Filter # :nodoc:
+          def initialize(runnable, file, line)
+            @runnable, @file = runnable, File.expand_path(file)
+            @line = line.to_i if line
+          end
+
+          def ===(method)
+            return unless @runnable.method_defined?(method)
+
+            if @line
+              test_file, test_range = definition_for(@runnable.instance_method(method))
+              test_file == @file && test_range.include?(@line)
+            else
+              @runnable.instance_method(method).source_location.first == @file
+            end
+          end
+
+          private
+            def definition_for(method)
+              file, start_line = method.source_location
+              end_line = method.source.count("\n") + start_line - 1
+
+              return file, start_line..end_line
+            end
+        end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/testing/deprecation.rb b/activesupport/lib/active_support/testing/deprecation.rb
index 6c94c611b6..5dfa14eeba 100644
--- a/activesupport/lib/active_support/testing/deprecation.rb
+++ b/activesupport/lib/active_support/testing/deprecation.rb
@@ -3,8 +3,8 @@ require 'active_support/deprecation'
 module ActiveSupport
   module Testing
     module Deprecation #:nodoc:
-      def assert_deprecated(match = nil, &block)
-        result, warnings = collect_deprecations(&block)
+      def assert_deprecated(match = nil, deprecator = nil, &block)
+        result, warnings = collect_deprecations(deprecator, &block)
         assert !warnings.empty?, "Expected a deprecation warning within the block but received none"
         if match
           match = Regexp.new(Regexp.escape(match)) unless match.is_a?(Regexp)
@@ -13,22 +13,23 @@ module ActiveSupport
         result
       end
 
-      def assert_not_deprecated(&block)
-        result, deprecations = collect_deprecations(&block)
+      def assert_not_deprecated(deprecator = nil, &block)
+        result, deprecations = collect_deprecations(deprecator, &block)
         assert deprecations.empty?, "Expected no deprecation warning within the block but received #{deprecations.size}: \n  #{deprecations * "\n  "}"
         result
       end
 
-      def collect_deprecations
-        old_behavior = ActiveSupport::Deprecation.behavior
+      def collect_deprecations(deprecator = nil)
+        deprecator ||= ActiveSupport::Deprecation
+        old_behavior = deprecator.behavior
         deprecations = []
-        ActiveSupport::Deprecation.behavior = Proc.new do |message, callstack|
+        deprecator.behavior = Proc.new do |message, callstack|
           deprecations << message
         end
         result = yield
         [result, deprecations]
       ensure
-        ActiveSupport::Deprecation.behavior = old_behavior
+        deprecator.behavior = old_behavior
       end
     end
   end
diff --git a/activesupport/lib/active_support/testing/file_fixtures.rb b/activesupport/lib/active_support/testing/file_fixtures.rb
new file mode 100644
index 0000000000..affb84cda5
--- /dev/null
+++ b/activesupport/lib/active_support/testing/file_fixtures.rb
@@ -0,0 +1,34 @@
+module ActiveSupport
+  module Testing
+    # Adds simple access to sample files called file fixtures.
+    # File fixtures are normal files stored in
+    # <tt>ActiveSupport::TestCase.file_fixture_path</tt>.
+    #
+    # File fixtures are represented as +Pathname+ objects.
+    # This makes it easy to extract specific information:
+    #
+    #   file_fixture("example.txt").read # get the file's content
+    #   file_fixture("example.mp3").size # get the file size
+    module FileFixtures
+      extend ActiveSupport::Concern
+
+      included do
+        class_attribute :file_fixture_path, instance_writer: false
+      end
+
+      # Returns a +Pathname+ to the fixture file named +fixture_name+.
+      #
+      # Raises +ArgumentError+ if +fixture_name+ can't be found.
+      def file_fixture(fixture_name)
+        path = Pathname.new(File.join(file_fixture_path, fixture_name))
+
+        if path.exist?
+          path
+        else
+          msg = "the directory '%s' does not contain a file named '%s'"
+          raise ArgumentError, msg % [file_fixture_path, fixture_name]
+        end
+      end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
index 247df7423b..edf8b30a0a 100644
--- a/activesupport/lib/active_support/testing/isolation.rb
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -41,7 +41,23 @@ module ActiveSupport
           pid = fork do
             read.close
             yield
-            write.puts [Marshal.dump(self.dup)].pack("m")
+            begin
+              if error?
+                failures.map! { |e|
+                  begin
+                    Marshal.dump e
+                    e
+                  rescue TypeError
+                    ex = Exception.new e.message
+                    ex.set_backtrace e.backtrace
+                    Minitest::UnexpectedError.new ex
+                  end
+                }
+              end
+              result = Marshal.dump(self.dup)
+            end
+
+            write.puts [result].pack("m")
             exit!
           end
 
@@ -69,17 +85,17 @@ module ActiveSupport
           else
             Tempfile.open("isolation") do |tmpfile|
               env = {
-                ISOLATION_TEST: self.class.name,
-                ISOLATION_OUTPUT: tmpfile.path
+                'ISOLATION_TEST' => self.class.name,
+                'ISOLATION_OUTPUT' => tmpfile.path
               }
 
               load_paths = $-I.map {|p| "-I\"#{File.expand_path(p)}\"" }.join(" ")
               orig_args = ORIG_ARGV.join(" ")
               test_opts = "-n#{self.class.name}##{self.name}"
-              command = "#{Gem.ruby} #{load_paths} #{$0} #{orig_args} #{test_opts}"
+              command = "#{Gem.ruby} #{load_paths} #{$0} '#{orig_args}' #{test_opts}"
 
               # IO.popen lets us pass env in a cross-platform way
-              child = IO.popen([env, command])
+              child = IO.popen(env, command)
 
               begin
                 Process.wait(child.pid)
diff --git a/activesupport/lib/active_support/testing/method_call_assertions.rb b/activesupport/lib/active_support/testing/method_call_assertions.rb
new file mode 100644
index 0000000000..fccaa54f40
--- /dev/null
+++ b/activesupport/lib/active_support/testing/method_call_assertions.rb
@@ -0,0 +1,41 @@
+require 'minitest/mock'
+
+module ActiveSupport
+  module Testing
+    module MethodCallAssertions # :nodoc:
+      private
+        def assert_called(object, method_name, message = nil, times: 1, returns: nil)
+          times_called = 0
+
+          object.stub(method_name, proc { times_called += 1; returns }) { yield }
+
+          error = "Expected #{method_name} to be called #{times} times, " \
+            "but was called #{times_called} times"
+          error = "#{message}.\n#{error}" if message
+          assert_equal times, times_called, error
+        end
+
+        def assert_called_with(object, method_name, args = [], returns: nil)
+          mock = Minitest::Mock.new
+
+          if args.all? { |arg| arg.is_a?(Array) }
+            args.each { |arg| mock.expect(:call, returns, arg) }
+          else
+            mock.expect(:call, returns, args)
+          end
+
+          object.stub(method_name, mock) { yield }
+
+          mock.verify
+        end
+
+        def assert_not_called(object, method_name, message = nil, &block)
+          assert_called(object, method_name, message, times: 0, &block)
+        end
+
+        def stub_any_instance(klass, instance: klass.new)
+          klass.stub(:new, instance) { yield instance }
+        end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/testing/stream.rb b/activesupport/lib/active_support/testing/stream.rb
new file mode 100644
index 0000000000..895192ad05
--- /dev/null
+++ b/activesupport/lib/active_support/testing/stream.rb
@@ -0,0 +1,42 @@
+module ActiveSupport
+  module Testing
+    module Stream #:nodoc:
+      private
+
+      def silence_stream(stream)
+        old_stream = stream.dup
+        stream.reopen(IO::NULL)
+        stream.sync = true
+        yield
+      ensure
+        stream.reopen(old_stream)
+        old_stream.close
+      end
+
+      def quietly
+        silence_stream(STDOUT) do
+          silence_stream(STDERR) do
+            yield
+          end
+        end
+      end
+
+      def capture(stream)
+        stream = stream.to_s
+        captured_stream = Tempfile.new(stream)
+        stream_io = eval("$#{stream}")
+        origin_stream = stream_io.dup
+        stream_io.reopen(captured_stream)
+
+        yield
+
+        stream_io.rewind
+        return captured_stream.read
+      ensure
+        captured_stream.close
+        captured_stream.unlink
+        stream_io.reopen(origin_stream)
+      end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/testing/time_helpers.rb b/activesupport/lib/active_support/testing/time_helpers.rb
index 8c63815660..fca0947c5b 100644
--- a/activesupport/lib/active_support/testing/time_helpers.rb
+++ b/activesupport/lib/active_support/testing/time_helpers.rb
@@ -39,15 +39,16 @@ module ActiveSupport
         end
     end
 
-    # Containing helpers that helps you test passage of time.
+    # Contains helpers that help you test passage of time.
     module TimeHelpers
       # Changes current time to the time in the future or in the past by a given time difference by
-      # stubbing +Time.now+ and +Date.today+.
+      # stubbing +Time.now+, +Date.today+, and +DateTime.now+.
       #
-      #   Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00
+      #   Time.current     # => Sat, 09 Nov 2013 15:34:49 EST -05:00
       #   travel 1.day
-      #   Time.current # => Sun, 10 Nov 2013 15:34:49 EST -05:00
-      #   Date.current # => Sun, 10 Nov 2013
+      #   Time.current     # => Sun, 10 Nov 2013 15:34:49 EST -05:00
+      #   Date.current     # => Sun, 10 Nov 2013
+      #   DateTime.current # => Sun, 10 Nov 2013 15:34:49 -0500
       #
       # This method also accepts a block, which will return the current time back to its original
       # state at the end of the block:
@@ -61,13 +62,14 @@ module ActiveSupport
         travel_to Time.now + duration, &block
       end
 
-      # Changes current time to the given time by stubbing +Time.now+ and
-      # +Date.today+ to return the time or date passed into this method.
+      # Changes current time to the given time by stubbing +Time.now+,
+      # +Date.today+, and +DateTime.now+ to return the time or date passed into this method.
       #
-      #   Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00
+      #   Time.current     # => Sat, 09 Nov 2013 15:34:49 EST -05:00
       #   travel_to Time.new(2004, 11, 24, 01, 04, 44)
-      #   Time.current # => Wed, 24 Nov 2004 01:04:44 EST -05:00
-      #   Date.current # => Wed, 24 Nov 2004
+      #   Time.current     # => Wed, 24 Nov 2004 01:04:44 EST -05:00
+      #   Date.current     # => Wed, 24 Nov 2004
+      #   DateTime.current # => Wed, 24 Nov 2004 01:04:44 -0500
       #
       # Dates are taken as their timestamp at the beginning of the day in the
       # application time zone. <tt>Time.current</tt> returns said timestamp,
@@ -99,6 +101,7 @@ module ActiveSupport
 
         simple_stubs.stub_object(Time, :now, now)
         simple_stubs.stub_object(Date, :today, now.to_date)
+        simple_stubs.stub_object(DateTime, :now, now.to_datetime)
 
         if block_given?
           begin
diff --git a/activesupport/lib/active_support/time_with_zone.rb b/activesupport/lib/active_support/time_with_zone.rb
index 8ddf233b3e..910c1f91a5 100644
--- a/activesupport/lib/active_support/time_with_zone.rb
+++ b/activesupport/lib/active_support/time_with_zone.rb
@@ -1,3 +1,4 @@
+require 'active_support/duration'
 require 'active_support/values/time_zone'
 require 'active_support/core_ext/object/acts_like'
 
@@ -13,7 +14,7 @@ module ActiveSupport
   #   Time.zone = 'Eastern Time (US & Canada)'        # => 'Eastern Time (US & Canada)'
   #   Time.zone.local(2007, 2, 10, 15, 30, 45)        # => Sat, 10 Feb 2007 15:30:45 EST -05:00
   #   Time.zone.parse('2007-02-10 15:30:45')          # => Sat, 10 Feb 2007 15:30:45 EST -05:00
-  #   Time.zone.at(1170361845)                        # => Sat, 10 Feb 2007 15:30:45 EST -05:00
+  #   Time.zone.at(1171139445)                        # => Sat, 10 Feb 2007 15:30:45 EST -05:00
   #   Time.zone.now                                   # => Sun, 18 May 2008 13:07:55 EDT -04:00
   #   Time.utc(2007, 2, 10, 20, 30, 45).in_time_zone  # => Sat, 10 Feb 2007 15:30:45 EST -05:00
   #
@@ -40,6 +41,9 @@ module ActiveSupport
       'Time'
     end
 
+    PRECISIONS = Hash.new { |h, n| h[n] = "%FT%T.%#{n}N".freeze }
+    PRECISIONS[0] = '%FT%T'.freeze
+
     include Comparable
     attr_reader :time_zone
 
@@ -98,7 +102,7 @@ module ActiveSupport
     #   Time.zone = 'Eastern Time (US & Canada)'    # => 'Eastern Time (US & Canada)'
     #   Time.zone.now.utc?                          # => false
     def utc?
-      time_zone.name == 'UTC'
+      period.offset.abbreviation == :UTC || period.offset.abbreviation == :UCT
     end
     alias_method :gmt?, :utc?
 
@@ -131,7 +135,7 @@ module ActiveSupport
 
     # Returns a string of the object's date, time, zone and offset from UTC.
     #
-    #   Time.zone.now.httpdate  # => "Thu, 04 Dec 2014 11:00:25 EST -05:00"
+    #   Time.zone.now.inspect # => "Thu, 04 Dec 2014 11:00:25 EST -05:00"
     def inspect
       "#{time.strftime('%a, %d %b %Y %H:%M:%S')} #{zone} #{formatted_offset}"
     end
@@ -141,11 +145,7 @@ module ActiveSupport
     #
     #   Time.zone.now.xmlschema  # => "2014-12-04T11:02:37-05:00"
     def xmlschema(fraction_digits = 0)
-      fraction = if fraction_digits.to_i > 0
-        (".%06i" % time.usec)[0, fraction_digits.to_i + 1]
-      end
-
-      "#{time.strftime("%Y-%m-%dT%H:%M:%S")}#{fraction}#{formatted_offset(true, 'Z')}"
+      "#{time.strftime(PRECISIONS[fraction_digits.to_i])}#{formatted_offset(true, 'Z'.freeze)}"
     end
     alias_method :iso8601, :xmlschema
 
@@ -169,12 +169,13 @@ module ActiveSupport
       end
     end
 
-    def encode_with(coder)
-      if coder.respond_to?(:represent_object)
-        coder.represent_object(nil, utc)
-      else
-        coder.represent_scalar(nil, utc.strftime("%Y-%m-%d %H:%M:%S.%9NZ"))
-      end
+    def init_with(coder) #:nodoc:
+      initialize(coder['utc'], coder['zone'], coder['time'])
+    end
+
+    def encode_with(coder) #:nodoc:
+      coder.tag = '!ruby/object:ActiveSupport::TimeWithZone'
+      coder.map = { 'utc' => utc, 'zone' => time_zone, 'time' => time }
     end
 
     # Returns a string of the object's date and time in the format used by
@@ -244,15 +245,16 @@ module ActiveSupport
       utc.future?
     end
 
+    # Returns +true+ if +other+ is equal to current object.
     def eql?(other)
-      utc.eql?(other)
+      other.eql?(utc)
     end
 
     def hash
       utc.hash
     end
 
-    # Adds an interval of time to the current object's time and return that
+    # Adds an interval of time to the current object's time and returns that
     # value as a new TimeWithZone object.
     #
     #   Time.zone = 'Eastern Time (US & Canada)' # => 'Eastern Time (US & Canada)'
@@ -327,6 +329,11 @@ module ActiveSupport
       EOV
     end
 
+    # Returns Array of parts of Time in sequence of
+    # [seconds, minutes, hours, day, month, year, weekday, yearday, dst?, zone].
+    #
+    #   now = Time.zone.now     # => Tue, 18 Aug 2015 02:29:27 UTC +00:00
+    #   now.to_a                # => [27, 29, 2, 18, 8, 2015, 2, 230, false, "UTC"]
     def to_a
       [time.sec, time.min, time.hour, time.day, time.mon, time.year, time.wday, time.yday, dst?, zone]
     end
@@ -356,11 +363,15 @@ module ActiveSupport
       utc.to_r
     end
 
-    # Return an instance of Time in the system timezone.
+    # Returns an instance of Time in the system timezone.
     def to_time
       utc.to_time
     end
 
+    # Returns an instance of DateTime with the timezone's UTC offset
+    #
+    #   Time.zone.now.to_datetime                         # => Tue, 18 Aug 2015 02:32:20 +0000
+    #   Time.current.in_time_zone('Hawaii').to_datetime   # => Mon, 17 Aug 2015 16:32:20 -1000
     def to_datetime
       utc.to_datetime.new_offset(Rational(utc_offset, 86_400))
     end
@@ -376,6 +387,11 @@ module ActiveSupport
     end
     alias_method :kind_of?, :is_a?
 
+    # An instance of ActiveSupport::TimeWithZone is never blank
+    def blank?
+      false
+    end
+
     def freeze
       period; utc; time # preload instance variables before freezing
       super
diff --git a/activesupport/lib/active_support/values/time_zone.rb b/activesupport/lib/active_support/values/time_zone.rb
index 728b53849d..9f4bb6762d 100644
--- a/activesupport/lib/active_support/values/time_zone.rb
+++ b/activesupport/lib/active_support/values/time_zone.rb
@@ -1,5 +1,5 @@
 require 'tzinfo'
-require 'thread_safe'
+require 'concurrent'
 require 'active_support/core_ext/object/blank'
 require 'active_support/core_ext/object/try'
 
@@ -23,15 +23,9 @@ module ActiveSupport
   #     config.time_zone = 'Eastern Time (US & Canada)'
   #   end
   #
-  #   Time.zone      # => #<TimeZone:0x514834...>
+  #   Time.zone      # => #<ActiveSupport::TimeZone:0x514834...>
   #   Time.zone.name # => "Eastern Time (US & Canada)"
   #   Time.zone.now  # => Sun, 18 May 2008 14:30:44 EDT -04:00
-  #
-  # The version of TZInfo bundled with Active Support only includes the
-  # definitions necessary to support the zones defined by the TimeZone class.
-  # If you need to use zones that aren't defined by TimeZone, you'll need to
-  # install the TZInfo gem (if a recent version of the gem is installed locally,
-  # this will be used instead of the bundled version.)
   class TimeZone
     # Keys are Rails TimeZone names, values are TZInfo identifiers.
     MAPPING = {
@@ -189,13 +183,13 @@ module ActiveSupport
     UTC_OFFSET_WITH_COLON = '%s%02d:%02d'
     UTC_OFFSET_WITHOUT_COLON = UTC_OFFSET_WITH_COLON.tr(':', '')
 
-    @lazy_zones_map = ThreadSafe::Cache.new
+    @lazy_zones_map = Concurrent::Map.new
 
     class << self
       # Assumes self represents an offset from UTC in seconds (as returned from
       # Time#utc_offset) and turns this into an +HH:MM formatted string.
       #
-      #   TimeZone.seconds_to_utc_offset(-21_600) # => "-06:00"
+      #   ActiveSupport::TimeZone.seconds_to_utc_offset(-21_600) # => "-06:00"
       def seconds_to_utc_offset(seconds, colon = true)
         format = colon ? UTC_OFFSET_WITH_COLON : UTC_OFFSET_WITHOUT_COLON
         sign = (seconds < 0 ? '-' : '+')
@@ -224,13 +218,6 @@ module ActiveSupport
         @zones ||= zones_map.values.sort
       end
 
-      def zones_map
-        @zones_map ||= begin
-          MAPPING.each_key {|place| self[place]} # load all the zones
-          @lazy_zones_map
-        end
-      end
-
       # Locate a specific time zone object. If the argument is a string, it
       # is interpreted to mean the name of the timezone to locate. If it is a
       # numeric value it is either the hour offset, or the second offset, of the
@@ -257,6 +244,14 @@ module ActiveSupport
       def us_zones
         @us_zones ||= all.find_all { |z| z.name =~ /US|Arizona|Indiana|Hawaii|Alaska/ }
       end
+
+      private
+        def zones_map
+          @zones_map ||= begin
+            MAPPING.each_key {|place| self[place]} # load all the zones
+            @lazy_zones_map
+          end
+        end
     end
 
     include Comparable
@@ -284,8 +279,12 @@ module ActiveSupport
       end
     end
 
-    # Returns the offset of this time zone as a formatted string, of the
-    # format "+HH:MM".
+    # Returns a formatted string of the offset from UTC, or an alternative
+    # string if the time zone is already UTC.
+    #
+    #   zone = ActiveSupport::TimeZone['Central Time (US & Canada)']
+    #   zone.formatted_offset        # => "-06:00"
+    #   zone.formatted_offset(false) # => "-0600"
     def formatted_offset(colon=true, alternate_utc_string = nil)
       utc_offset == 0 && alternate_utc_string || self.class.seconds_to_utc_offset(utc_offset, colon)
     end
@@ -347,24 +346,31 @@ module ActiveSupport
     #
     #   Time.zone.parse('Mar 2000') # => Wed, 01 Mar 2000 00:00:00 HST -10:00
     def parse(str, now=now())
-      parts = Date._parse(str, false)
-      return if parts.empty?
-
-      time = Time.new(
-        parts.fetch(:year, now.year),
-        parts.fetch(:mon, now.month),
-        parts.fetch(:mday, parts[:year] || parts[:mon] ? 1 : now.day),
-        parts.fetch(:hour, 0),
-        parts.fetch(:min, 0),
-        parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0),
-        parts.fetch(:offset, 0)
-      )
-
-      if parts[:offset]
-        TimeWithZone.new(time.utc, self)
-      else
-        TimeWithZone.new(nil, self, time)
-      end
+      parts_to_time(Date._parse(str, false), now)
+    end
+
+    # Parses +str+ according to +format+ and returns an ActiveSupport::TimeWithZone.
+    #
+    # Assumes that +str+ is a time in the time zone +self+,
+    # unless +format+ includes an explicit time zone.
+    # (This is the same behavior as +parse+.)
+    # In either case, the returned TimeWithZone has the timezone of +self+.
+    #
+    #   Time.zone = 'Hawaii'                   # => "Hawaii"
+    #   Time.zone.strptime('1999-12-31 14:00:00', '%Y-%m-%d %H:%M:%S') # => Fri, 31 Dec 1999 14:00:00 HST -10:00
+    #
+    # If upper components are missing from the string, they are supplied from
+    # TimeZone#now:
+    #
+    #   Time.zone.now                              # => Fri, 31 Dec 1999 14:00:00 HST -10:00
+    #   Time.zone.strptime('22:30:00', '%H:%M:%S') # => Fri, 31 Dec 1999 22:30:00 HST -10:00
+    #
+    # However, if the date component is not provided, but any other upper
+    # components are supplied, then the day of the month defaults to 1:
+    #
+    #   Time.zone.strptime('Mar 2000', '%b %Y') # => Wed, 01 Mar 2000 00:00:00 HST -10:00
+    def strptime(str, format, now=now())
+      parts_to_time(DateTime._strptime(str, format), now)
     end
 
     # Returns an ActiveSupport::TimeWithZone instance representing the current
@@ -376,7 +382,7 @@ module ActiveSupport
       time_now.utc.in_time_zone(self)
     end
 
-    # Return the current date in this time zone.
+    # Returns the current date in this time zone.
     def today
       tzinfo.now.to_date
     end
@@ -420,7 +426,36 @@ module ActiveSupport
       tzinfo.periods_for_local(time)
     end
 
+    def init_with(coder) #:nodoc:
+      initialize(coder['name'])
+    end
+
+    def encode_with(coder) #:nodoc:
+      coder.tag ="!ruby/object:#{self.class}"
+      coder.map = { 'name' => tzinfo.name }
+    end
+
     private
+      def parts_to_time(parts, now)
+        return if parts.empty?
+
+        time = Time.new(
+          parts.fetch(:year, now.year),
+          parts.fetch(:mon, now.month),
+          parts.fetch(:mday, parts[:year] || parts[:mon] ? 1 : now.day),
+          parts.fetch(:hour, 0),
+          parts.fetch(:min, 0),
+          parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0),
+          parts.fetch(:offset, 0)
+        )
+
+        if parts[:offset]
+          TimeWithZone.new(time.utc, self)
+        else
+          TimeWithZone.new(nil, self, time)
+        end
+      end
+
       def time_now
         Time.now
       end
diff --git a/activesupport/lib/active_support/values/unicode_tables.dat b/activesupport/lib/active_support/values/unicode_tables.dat
index 760be4c07a..dd2c178fb6 100644
--- a/activesupport/lib/active_support/values/unicode_tables.dat
+++ b/activesupport/lib/active_support/values/unicode_tables.dat
diff --git a/activesupport/lib/active_support/xml_mini.rb b/activesupport/lib/active_support/xml_mini.rb
index 009ee4db90..df7b081993 100644
--- a/activesupport/lib/active_support/xml_mini.rb
+++ b/activesupport/lib/active_support/xml_mini.rb
@@ -78,6 +78,9 @@ module ActiveSupport
       )
     end
 
+    attr_accessor :depth
+    self.depth = 100
+
     delegate :parse, :to => :backend
 
     def backend
diff --git a/activesupport/lib/active_support/xml_mini/jdom.rb b/activesupport/lib/active_support/xml_mini/jdom.rb
index f303daa1a7..94751bbc04 100644
--- a/activesupport/lib/active_support/xml_mini/jdom.rb
+++ b/activesupport/lib/active_support/xml_mini/jdom.rb
@@ -46,7 +46,7 @@ module ActiveSupport
         xml_string_reader = StringReader.new(data)
         xml_input_source = InputSource.new(xml_string_reader)
         doc = @dbf.new_document_builder.parse(xml_input_source)
-        merge_element!({CONTENT_KEY => ''}, doc.document_element)
+        merge_element!({CONTENT_KEY => ''}, doc.document_element, XmlMini.depth)
       end
     end
 
@@ -58,9 +58,10 @@ module ActiveSupport
     #   Hash to merge the converted element into.
     # element::
     #   XML element to merge into hash
-    def merge_element!(hash, element)
+    def merge_element!(hash, element, depth)
+      raise 'Document too deep!' if depth == 0
       delete_empty(hash)
-      merge!(hash, element.tag_name, collapse(element))
+      merge!(hash, element.tag_name, collapse(element, depth))
     end
 
     def delete_empty(hash)
@@ -71,14 +72,14 @@ module ActiveSupport
     #
     # element::
     #   The document element to be collapsed.
-    def collapse(element)
+    def collapse(element, depth)
       hash = get_attributes(element)
 
       child_nodes = element.child_nodes
       if child_nodes.length > 0
         (0...child_nodes.length).each do |i|
           child = child_nodes.item(i)
-          merge_element!(hash, child) unless child.node_type == Node.TEXT_NODE
+          merge_element!(hash, child, depth - 1) unless child.node_type == Node.TEXT_NODE
         end
         merge_texts!(hash, element) unless empty_content?(element)
         hash
diff --git a/activesupport/lib/active_support/xml_mini/libxml.rb b/activesupport/lib/active_support/xml_mini/libxml.rb
index 47a2824186..bb0ea9c582 100644
--- a/activesupport/lib/active_support/xml_mini/libxml.rb
+++ b/activesupport/lib/active_support/xml_mini/libxml.rb
@@ -75,5 +75,5 @@ module LibXML #:nodoc:
   end
 end
 
-LibXML::XML::Document.send(:include, LibXML::Conversions::Document)
-LibXML::XML::Node.send(:include, LibXML::Conversions::Node)
+LibXML::XML::Document.include(LibXML::Conversions::Document)
+LibXML::XML::Node.include(LibXML::Conversions::Node)
diff --git a/activesupport/lib/active_support/xml_mini/nokogiri.rb b/activesupport/lib/active_support/xml_mini/nokogiri.rb
index 7398d4fa82..619cc7522d 100644
--- a/activesupport/lib/active_support/xml_mini/nokogiri.rb
+++ b/activesupport/lib/active_support/xml_mini/nokogiri.rb
@@ -77,7 +77,7 @@ module ActiveSupport
       end
     end
 
-    Nokogiri::XML::Document.send(:include, Conversions::Document)
-    Nokogiri::XML::Node.send(:include, Conversions::Node)
+    Nokogiri::XML::Document.include(Conversions::Document)
+    Nokogiri::XML::Node.include(Conversions::Node)
   end
 end
diff --git a/activesupport/lib/active_support/xml_mini/rexml.rb b/activesupport/lib/active_support/xml_mini/rexml.rb
index 5c7c78bf70..924ed72345 100644
--- a/activesupport/lib/active_support/xml_mini/rexml.rb
+++ b/activesupport/lib/active_support/xml_mini/rexml.rb
@@ -29,7 +29,7 @@ module ActiveSupport
         doc = REXML::Document.new(data)
 
         if doc.root
-          merge_element!({}, doc.root)
+          merge_element!({}, doc.root, XmlMini.depth)
         else
           raise REXML::ParseException,
             "The document #{doc.to_s.inspect} does not have a valid root"
@@ -44,19 +44,20 @@ module ActiveSupport
       #   Hash to merge the converted element into.
       # element::
       #   XML element to merge into hash
-      def merge_element!(hash, element)
-        merge!(hash, element.name, collapse(element))
+      def merge_element!(hash, element, depth)
+        raise REXML::ParseException, "The document is too deep" if depth == 0
+        merge!(hash, element.name, collapse(element, depth))
       end
 
       # Actually converts an XML document element into a data structure.
       #
       # element::
       #   The document element to be collapsed.
-      def collapse(element)
+      def collapse(element, depth)
         hash = get_attributes(element)
 
         if element.has_elements?
-          element.each_element {|child| merge_element!(hash, child) }
+          element.each_element {|child| merge_element!(hash, child, depth - 1) }
           merge_texts!(hash, element) unless empty_content?(element)
           hash
         else
diff --git a/activesupport/test/abstract_unit.rb b/activesupport/test/abstract_unit.rb
index f65ec962f9..c0e23e89f7 100644
--- a/activesupport/test/abstract_unit.rb
+++ b/activesupport/test/abstract_unit.rb
@@ -15,6 +15,7 @@ silence_warnings do
 end
 
 require 'active_support/testing/autorun'
+require 'active_support/testing/method_call_assertions'
 
 ENV['NO_RELOAD'] = '1'
 require 'active_support'
@@ -37,9 +38,6 @@ def jruby_skip(message = '')
   skip message if defined?(JRUBY_VERSION)
 end
 
-require 'mocha/setup' # FIXME: stop using mocha
-
-# FIXME: we have tests that depend on run order, we should fix that and
-# remove this method call.
-require 'active_support/test_case'
-ActiveSupport::TestCase.test_order = :sorted
+class ActiveSupport::TestCase
+  include ActiveSupport::Testing::MethodCallAssertions
+end
diff --git a/activesupport/test/array_inquirer_test.rb b/activesupport/test/array_inquirer_test.rb
new file mode 100644
index 0000000000..263ab3802b
--- /dev/null
+++ b/activesupport/test/array_inquirer_test.rb
@@ -0,0 +1,41 @@
+require 'abstract_unit'
+require 'active_support/core_ext/array'
+
+class ArrayInquirerTest < ActiveSupport::TestCase
+  def setup
+    @array_inquirer = ActiveSupport::ArrayInquirer.new([:mobile, :tablet, 'api'])
+  end
+
+  def test_individual
+    assert @array_inquirer.mobile?
+    assert @array_inquirer.tablet?
+    assert_not @array_inquirer.desktop?
+  end
+
+  def test_any
+    assert @array_inquirer.any?(:mobile, :desktop)
+    assert @array_inquirer.any?(:watch, :tablet)
+    assert_not @array_inquirer.any?(:desktop, :watch)
+  end
+
+  def test_any_string_symbol_mismatch
+    assert @array_inquirer.any?('mobile')
+    assert @array_inquirer.any?(:api)
+  end
+
+  def test_any_with_block
+    assert @array_inquirer.any? { |v| v == :mobile }
+    assert_not @array_inquirer.any? { |v| v == :desktop }
+  end
+
+  def test_respond_to
+    assert_respond_to @array_inquirer, :development?
+  end
+
+  def test_inquiry
+    result = [:mobile, :tablet, 'api'].inquiry
+
+    assert_instance_of ActiveSupport::ArrayInquirer, result
+    assert_equal @array_inquirer, result
+  end
+end
diff --git a/activesupport/test/autoloading_fixtures/a/c/e/f.rb b/activesupport/test/autoloading_fixtures/a/c/e/f.rb
deleted file mode 100644
index 57dba5a307..0000000000
--- a/activesupport/test/autoloading_fixtures/a/c/e/f.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-class A::C::E::F
-end
\ No newline at end of file
diff --git a/activesupport/test/autoloading_fixtures/a/c/em/f.rb b/activesupport/test/autoloading_fixtures/a/c/em/f.rb
new file mode 100644
index 0000000000..8b28e19148
--- /dev/null
+++ b/activesupport/test/autoloading_fixtures/a/c/em/f.rb
@@ -0,0 +1,2 @@
+class A::C::EM::F
+end
\ No newline at end of file
diff --git a/activesupport/test/autoloading_fixtures/d.rb b/activesupport/test/autoloading_fixtures/d.rb
new file mode 100644
index 0000000000..45c794d4ca
--- /dev/null
+++ b/activesupport/test/autoloading_fixtures/d.rb
@@ -0,0 +1,2 @@
+class D
+end
\ No newline at end of file
diff --git a/activesupport/test/autoloading_fixtures/e.rb b/activesupport/test/autoloading_fixtures/e.rb
deleted file mode 100644
index 2f59e4fb75..0000000000
--- a/activesupport/test/autoloading_fixtures/e.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-class E
-end
\ No newline at end of file
diff --git a/activesupport/test/autoloading_fixtures/em.rb b/activesupport/test/autoloading_fixtures/em.rb
new file mode 100644
index 0000000000..16a1838667
--- /dev/null
+++ b/activesupport/test/autoloading_fixtures/em.rb
@@ -0,0 +1,2 @@
+class EM
+end
\ No newline at end of file
diff --git a/activesupport/test/caching_test.rb b/activesupport/test/caching_test.rb
index 98f3ea7a14..fb52613a23 100644
--- a/activesupport/test/caching_test.rb
+++ b/activesupport/test/caching_test.rb
@@ -133,37 +133,42 @@ class CacheStoreSettingTest < ActiveSupport::TestCase
   end
 
   def test_mem_cache_fragment_cache_store
-    Dalli::Client.expects(:new).with(%w[localhost], {})
-    store = ActiveSupport::Cache.lookup_store :mem_cache_store, "localhost"
-    assert_kind_of(ActiveSupport::Cache::MemCacheStore, store)
+    assert_called_with(Dalli::Client, :new, [%w[localhost], {}]) do
+      store = ActiveSupport::Cache.lookup_store :mem_cache_store, "localhost"
+      assert_kind_of(ActiveSupport::Cache::MemCacheStore, store)
+    end
   end
 
   def test_mem_cache_fragment_cache_store_with_given_mem_cache
     mem_cache = Dalli::Client.new
-    Dalli::Client.expects(:new).never
-    store = ActiveSupport::Cache.lookup_store :mem_cache_store, mem_cache
-    assert_kind_of(ActiveSupport::Cache::MemCacheStore, store)
+    assert_not_called(Dalli::Client, :new) do
+      store = ActiveSupport::Cache.lookup_store :mem_cache_store, mem_cache
+      assert_kind_of(ActiveSupport::Cache::MemCacheStore, store)
+    end
   end
 
   def test_mem_cache_fragment_cache_store_with_not_dalli_client
-    Dalli::Client.expects(:new).never
-    memcache = Object.new
-    assert_raises(ArgumentError) do
-      ActiveSupport::Cache.lookup_store :mem_cache_store, memcache
+    assert_not_called(Dalli::Client, :new) do
+      memcache = Object.new
+      assert_raises(ArgumentError) do
+        ActiveSupport::Cache.lookup_store :mem_cache_store, memcache
+      end
     end
   end
 
   def test_mem_cache_fragment_cache_store_with_multiple_servers
-    Dalli::Client.expects(:new).with(%w[localhost 192.168.1.1], {})
-    store = ActiveSupport::Cache.lookup_store :mem_cache_store, "localhost", '192.168.1.1'
-    assert_kind_of(ActiveSupport::Cache::MemCacheStore, store)
+    assert_called_with(Dalli::Client, :new, [%w[localhost 192.168.1.1], {}]) do
+      store = ActiveSupport::Cache.lookup_store :mem_cache_store, "localhost", '192.168.1.1'
+      assert_kind_of(ActiveSupport::Cache::MemCacheStore, store)
+    end
   end
 
   def test_mem_cache_fragment_cache_store_with_options
-    Dalli::Client.expects(:new).with(%w[localhost 192.168.1.1], { :timeout => 10 })
-    store = ActiveSupport::Cache.lookup_store :mem_cache_store, "localhost", '192.168.1.1', :namespace => 'foo', :timeout => 10
-    assert_kind_of(ActiveSupport::Cache::MemCacheStore, store)
-    assert_equal 'foo', store.options[:namespace]
+    assert_called_with(Dalli::Client, :new, [%w[localhost 192.168.1.1], { :timeout => 10 }]) do
+      store = ActiveSupport::Cache.lookup_store :mem_cache_store, "localhost", '192.168.1.1', :namespace => 'foo', :timeout => 10
+      assert_kind_of(ActiveSupport::Cache::MemCacheStore, store)
+      assert_equal 'foo', store.options[:namespace]
+    end
   end
 
   def test_object_assigned_fragment_cache_store
@@ -224,13 +229,15 @@ module CacheStoreBehavior
 
   def test_fetch_without_cache_miss
     @cache.write('foo', 'bar')
-    @cache.expects(:write).never
-    assert_equal 'bar', @cache.fetch('foo') { 'baz' }
+    assert_not_called(@cache, :write) do
+      assert_equal 'bar', @cache.fetch('foo') { 'baz' }
+    end
   end
 
   def test_fetch_with_cache_miss
-    @cache.expects(:write).with('foo', 'baz', @cache.options)
-    assert_equal 'baz', @cache.fetch('foo') { 'baz' }
+    assert_called_with(@cache, :write, ['foo', 'baz', @cache.options]) do
+      assert_equal 'baz', @cache.fetch('foo') { 'baz' }
+    end
   end
 
   def test_fetch_with_cache_miss_passes_key_to_block
@@ -245,15 +252,18 @@ module CacheStoreBehavior
 
   def test_fetch_with_forced_cache_miss
     @cache.write('foo', 'bar')
-    @cache.expects(:read).never
-    @cache.expects(:write).with('foo', 'bar', @cache.options.merge(:force => true))
-    @cache.fetch('foo', :force => true) { 'bar' }
+    assert_not_called(@cache, :read) do
+      assert_called_with(@cache, :write, ['foo', 'bar', @cache.options.merge(:force => true)]) do
+        @cache.fetch('foo', :force => true) { 'bar' }
+      end
+    end
   end
 
   def test_fetch_with_cached_nil
     @cache.write('foo', nil)
-    @cache.expects(:write).never
-    assert_nil @cache.fetch('foo') { 'baz' }
+    assert_not_called(@cache, :write) do
+      assert_nil @cache.fetch('foo') { 'baz' }
+    end
   end
 
   def test_should_read_and_write_hash
@@ -288,8 +298,9 @@ module CacheStoreBehavior
     @cache.write('foo', 'bar', :expires_in => 10)
     @cache.write('fu', 'baz')
     @cache.write('fud', 'biz')
-    Time.stubs(:now).returns(time + 11)
-    assert_equal({"fu" => "baz"}, @cache.read_multi('foo', 'fu'))
+    Time.stub(:now, time + 11) do
+      assert_equal({"fu" => "baz"}, @cache.read_multi('foo', 'fu'))
+    end
   end
 
   def test_fetch_multi
@@ -303,8 +314,9 @@ module CacheStoreBehavior
   end
 
   def test_multi_with_objects
-    foo = stub(:title => 'FOO!', :cache_key => 'foo')
-    bar = stub(:cache_key => 'bar')
+    cache_struct = Struct.new(:cache_key, :title)
+    foo = cache_struct.new('foo', 'FOO!')
+    bar = cache_struct.new('bar')
 
     @cache.write('bar', 'BAM!')
 
@@ -387,54 +399,74 @@ module CacheStoreBehavior
 
   def test_expires_in
     time = Time.local(2008, 4, 24)
-    Time.stubs(:now).returns(time)
 
-    @cache.write('foo', 'bar')
-    assert_equal 'bar', @cache.read('foo')
+    Time.stub(:now, time) do
+      @cache.write('foo', 'bar')
+      assert_equal 'bar', @cache.read('foo')
+    end
 
-    Time.stubs(:now).returns(time + 30)
-    assert_equal 'bar', @cache.read('foo')
+    Time.stub(:now, time + 30) do
+      assert_equal 'bar', @cache.read('foo')
+    end
 
-    Time.stubs(:now).returns(time + 61)
-    assert_nil @cache.read('foo')
+    Time.stub(:now, time + 61) do
+      assert_nil @cache.read('foo')
+    end
   end
 
-  def test_race_condition_protection
-    time = Time.now
-    @cache.write('foo', 'bar', :expires_in => 60)
-    Time.stubs(:now).returns(time + 61)
-    result = @cache.fetch('foo', :race_condition_ttl => 10) do
-      assert_equal 'bar', @cache.read('foo')
-      "baz"
+  def test_race_condition_protection_skipped_if_not_defined
+    @cache.write('foo', 'bar')
+    time = @cache.send(:read_entry, 'foo', {}).expires_at
+
+    Time.stub(:now, Time.at(time)) do
+      result = @cache.fetch('foo') do
+        assert_equal nil, @cache.read('foo')
+        'baz'
+      end
+      assert_equal 'baz', result
     end
-    assert_equal "baz", result
   end
 
   def test_race_condition_protection_is_limited
     time = Time.now
     @cache.write('foo', 'bar', :expires_in => 60)
-    Time.stubs(:now).returns(time + 71)
-    result = @cache.fetch('foo', :race_condition_ttl => 10) do
-      assert_equal nil, @cache.read('foo')
-      "baz"
+    Time.stub(:now, time + 71) do
+      result = @cache.fetch('foo', :race_condition_ttl => 10) do
+        assert_equal nil, @cache.read('foo')
+        "baz"
+      end
+      assert_equal "baz", result
     end
-    assert_equal "baz", result
   end
 
   def test_race_condition_protection_is_safe
     time = Time.now
     @cache.write('foo', 'bar', :expires_in => 60)
-    Time.stubs(:now).returns(time + 61)
-    begin
-      @cache.fetch('foo', :race_condition_ttl => 10) do
+    Time.stub(:now, time + 61) do
+      begin
+        @cache.fetch('foo', :race_condition_ttl => 10) do
+          assert_equal 'bar', @cache.read('foo')
+          raise ArgumentError.new
+        end
+      rescue ArgumentError
+      end
+      assert_equal "bar", @cache.read('foo')
+    end
+    Time.stub(:now, time + 91) do
+      assert_nil @cache.read('foo')
+    end
+  end
+
+  def test_race_condition_protection
+    time = Time.now
+    @cache.write('foo', 'bar', :expires_in => 60)
+    Time.stub(:now, time + 61) do
+      result = @cache.fetch('foo', :race_condition_ttl => 10) do
         assert_equal 'bar', @cache.read('foo')
-        raise ArgumentError.new
+        "baz"
       end
-    rescue ArgumentError
+      assert_equal "baz", result
     end
-    assert_equal "bar", @cache.read('foo')
-    Time.stubs(:now).returns(time + 91)
-    assert_nil @cache.read('foo')
   end
 
   def test_crazy_key_characters
@@ -458,6 +490,34 @@ module CacheStoreBehavior
     assert_equal({key => "bar"}, @cache.read_multi(key))
     assert @cache.delete(key)
   end
+
+  def test_cache_hit_instrumentation
+    key = "test_key"
+    subscribe_executed = false
+    ActiveSupport::Notifications.subscribe "cache_read.active_support" do |name, start, finish, id, payload|
+      subscribe_executed = true
+      assert_equal :fetch, payload[:super_operation]
+      assert payload[:hit]
+    end
+    assert @cache.write(key, "1", :raw => true)
+    assert @cache.fetch(key) {}
+    assert subscribe_executed
+  ensure
+    ActiveSupport::Notifications.unsubscribe "cache_read.active_support"
+  end
+
+  def test_cache_miss_instrumentation
+    subscribe_executed = false
+    ActiveSupport::Notifications.subscribe "cache_read.active_support" do |name, start, finish, id, payload|
+      subscribe_executed = true
+      assert_equal :fetch, payload[:super_operation]
+      assert_not payload[:hit]
+    end
+    assert_not @cache.fetch("bad_key") {}
+    assert subscribe_executed
+  ensure
+    ActiveSupport::Notifications.unsubscribe "cache_read.active_support"
+  end
 end
 
 # https://rails.lighthouseapp.com/projects/8994/tickets/6225-memcachestore-cant-deal-with-umlauts-and-special-characters
@@ -624,37 +684,37 @@ module AutoloadingCacheBehavior
   include DependenciesTestHelpers
   def test_simple_autoloading
     with_autoloading_fixtures do
-      @cache.write('foo', E.new)
+      @cache.write('foo', EM.new)
     end
 
-    remove_constants(:E)
+    remove_constants(:EM)
     ActiveSupport::Dependencies.clear
 
     with_autoloading_fixtures do
-      assert_kind_of E, @cache.read('foo')
+      assert_kind_of EM, @cache.read('foo')
     end
 
-    remove_constants(:E)
+    remove_constants(:EM)
     ActiveSupport::Dependencies.clear
   end
 
   def test_two_classes_autoloading
     with_autoloading_fixtures do
-      @cache.write('foo', [E.new, ClassFolder.new])
+      @cache.write('foo', [EM.new, ClassFolder.new])
     end
 
-    remove_constants(:E, :ClassFolder)
+    remove_constants(:EM, :ClassFolder)
     ActiveSupport::Dependencies.clear
 
     with_autoloading_fixtures do
       loaded = @cache.read('foo')
       assert_kind_of Array, loaded
       assert_equal 2, loaded.size
-      assert_kind_of E, loaded[0]
+      assert_kind_of EM, loaded[0]
       assert_kind_of ClassFolder, loaded[1]
     end
 
-    remove_constants(:E, :ClassFolder)
+    remove_constants(:EM, :ClassFolder)
     ActiveSupport::Dependencies.clear
   end
 end
@@ -672,6 +732,7 @@ class FileStoreTest < ActiveSupport::TestCase
 
   def teardown
     FileUtils.rm_r(cache_dir)
+  rescue Errno::ENOENT
   end
 
   def cache_dir
@@ -691,11 +752,21 @@ class FileStoreTest < ActiveSupport::TestCase
     assert File.exist?(filepath)
   end
 
+  def test_clear_without_cache_dir
+    FileUtils.rm_r(cache_dir)
+    @cache.clear
+  end
+
   def test_long_keys
     @cache.write("a"*10000, 1)
     assert_equal 1, @cache.read("a"*10000)
   end
 
+  def test_long_uri_encoded_keys
+    @cache.write("%"*870, 1)
+    assert_equal 1, @cache.read("%"*870)
+  end
+
   def test_key_transformation
     key = @cache.send(:key_file_path, "views/index?id=1")
     assert_equal "views/index?id=1", @cache.send(:file_path_key, key)
@@ -747,9 +818,10 @@ class FileStoreTest < ActiveSupport::TestCase
   end
 
   def test_log_exception_when_cache_read_fails
-    File.expects(:exist?).raises(StandardError, "failed")
-    @cache.send(:read_entry, "winston", {})
-    assert @buffer.string.present?
+    File.stub(:exist?, -> { raise StandardError.new("failed") }) do
+      @cache.send(:read_entry, "winston", {})
+      assert @buffer.string.present?
+    end
   end
 
   def test_cleanup_removes_all_expired_entries
@@ -757,11 +829,12 @@ class FileStoreTest < ActiveSupport::TestCase
     @cache.write('foo', 'bar', expires_in: 10)
     @cache.write('baz', 'qux')
     @cache.write('quux', 'corge', expires_in: 20)
-    Time.stubs(:now).returns(time + 15)
-    @cache.cleanup
-    assert_not @cache.exist?('foo')
-    assert @cache.exist?('baz')
-    assert @cache.exist?('quux')
+    Time.stub(:now, time + 15) do
+      @cache.cleanup
+      assert_not @cache.exist?('foo')
+      assert @cache.exist?('baz')
+      assert @cache.exist?('quux')
+    end
   end
 
   def test_write_with_unless_exist
@@ -998,10 +1071,6 @@ class NullStoreTest < ActiveSupport::TestCase
     end
     assert_nil @cache.read("name")
   end
-
-  def test_setting_nil_cache_store
-    assert ActiveSupport::Cache.lookup_store.class.name, ActiveSupport::Cache::NullStore.name
-  end
 end
 
 class CacheStoreLoggerTest < ActiveSupport::TestCase
@@ -1021,6 +1090,15 @@ class CacheStoreLoggerTest < ActiveSupport::TestCase
     @cache.mute { @cache.fetch('foo') { 'bar' } }
     assert @buffer.string.blank?
   end
+
+  def test_multi_read_loggin
+    @cache.write 'hello', 'goodbye'
+    @cache.write 'world', 'earth'
+
+    @cache.read_multi('hello', 'world')
+
+    assert_match "Caches multi read:\n- hello\n- world", @buffer.string
+  end
 end
 
 class CacheEntryTest < ActiveSupport::TestCase
@@ -1029,9 +1107,9 @@ class CacheEntryTest < ActiveSupport::TestCase
     assert !entry.expired?, 'entry not expired'
     entry = ActiveSupport::Cache::Entry.new("value", :expires_in => 60)
     assert !entry.expired?, 'entry not expired'
-    time = Time.now + 61
-    Time.stubs(:now).returns(time)
-    assert entry.expired?, 'entry is expired'
+    Time.stub(:now, Time.now + 61) do
+      assert entry.expired?, 'entry is expired'
+    end
   end
 
   def test_compress_values
diff --git a/activesupport/test/callbacks_test.rb b/activesupport/test/callbacks_test.rb
index f6abef8cee..3b00ff87a0 100644
--- a/activesupport/test/callbacks_test.rb
+++ b/activesupport/test/callbacks_test.rb
@@ -73,8 +73,8 @@ module CallbacksTest
 
   class PersonSkipper < Person
     skip_callback :save, :before, :before_save_method, :if => :yes
-    skip_callback :save, :after, :before_save_method, :unless => :yes
-    skip_callback :save, :after, :before_save_method, :if => :no
+    skip_callback :save, :after,  :after_save_method, :unless => :yes
+    skip_callback :save, :after,  :after_save_method, :if => :no
     skip_callback :save, :before, :before_save_method, :unless => :no
     skip_callback :save, :before, CallbackClass , :if => :yes
     def yes; true; end
@@ -766,34 +766,30 @@ module CallbacksTest
   end
 
   class CallbackFalseTerminatorWithoutConfigTest < ActiveSupport::TestCase
-    def test_returning_false_halts_callback_if_config_variable_is_not_set
+    def test_returning_false_does_not_halt_callback_if_config_variable_is_not_set
       obj = CallbackFalseTerminator.new
-      assert_deprecated do
-        obj.save
-        assert_equal :second, obj.halted
-        assert !obj.saved
-      end
+      obj.save
+      assert_equal nil, obj.halted
+      assert obj.saved
     end
   end
 
   class CallbackFalseTerminatorWithConfigTrueTest < ActiveSupport::TestCase
     def setup
-      ActiveSupport::Callbacks::CallbackChain.halt_and_display_warning_on_return_false = true
+      ActiveSupport::Callbacks.halt_and_display_warning_on_return_false = true
     end
 
-    def test_returning_false_halts_callback_if_config_variable_is_true
+    def test_returning_false_does_not_halt_callback_if_config_variable_is_true
       obj = CallbackFalseTerminator.new
-      assert_deprecated do
-        obj.save
-        assert_equal :second, obj.halted
-        assert !obj.saved
-      end
+      obj.save
+      assert_equal nil, obj.halted
+      assert obj.saved
     end
   end
 
   class CallbackFalseTerminatorWithConfigFalseTest < ActiveSupport::TestCase
     def setup
-      ActiveSupport::Callbacks::CallbackChain.halt_and_display_warning_on_return_false = false
+      ActiveSupport::Callbacks.halt_and_display_warning_on_return_false = false
     end
 
     def test_returning_false_does_not_halt_callback_if_config_variable_is_false
@@ -1021,7 +1017,7 @@ module CallbacksTest
         define_callbacks :foo
         n.times { set_callback :foo, :before, callback }
         def run; run_callbacks :foo; end
-        def self.skip(thing); skip_callback :foo, :before, thing; end
+        def self.skip(*things); skip_callback :foo, :before, *things; end
       }
     end
 
@@ -1070,11 +1066,11 @@ module CallbacksTest
       }
     end
 
-    def test_skip_lambda # removes nothing
+    def test_skip_lambda # raises error
       calls = []
       callback = ->(o) { calls << o }
       klass = build_class(callback)
-      10.times { klass.skip callback }
+      assert_raises(ArgumentError) { klass.skip callback }
       klass.new.run
       assert_equal 10, calls.length
     end
@@ -1088,11 +1084,29 @@ module CallbacksTest
       assert_equal 0, calls.length
     end
 
-    def test_skip_eval # removes nothing
+    def test_skip_string # raises error
       calls = []
       klass = build_class("bar")
       klass.class_eval { define_method(:bar) { calls << klass } }
-      klass.skip "bar"
+      assert_raises(ArgumentError) { klass.skip "bar" }
+      klass.new.run
+      assert_equal 1, calls.length
+    end
+
+    def test_skip_undefined_callback # raises error
+      calls = []
+      klass = build_class(:bar)
+      klass.class_eval { define_method(:bar) { calls << klass } }
+      assert_raises(ArgumentError) { klass.skip :qux }
+      klass.new.run
+      assert_equal 1, calls.length
+    end
+
+    def test_skip_without_raise # removes nothing
+      calls = []
+      klass = build_class(:bar)
+      klass.class_eval { define_method(:bar) { calls << klass } }
+      klass.skip :qux, raise: false
       klass.new.run
       assert_equal 1, calls.length
     end
diff --git a/activesupport/test/concern_test.rb b/activesupport/test/concern_test.rb
index 60bd8a06aa..8ea701cfb7 100644
--- a/activesupport/test/concern_test.rb
+++ b/activesupport/test/concern_test.rb
@@ -54,29 +54,54 @@ class ConcernTest < ActiveSupport::TestCase
     include Bar, Baz
   end
 
+  module Qux
+    module ClassMethods
+    end
+  end
+
   def setup
     @klass = Class.new
   end
 
   def test_module_is_included_normally
-    @klass.send(:include, Baz)
+    @klass.include(Baz)
     assert_equal "baz", @klass.new.baz
     assert @klass.included_modules.include?(ConcernTest::Baz)
   end
 
   def test_class_methods_are_extended
-    @klass.send(:include, Baz)
+    @klass.include(Baz)
     assert_equal "baz", @klass.baz
     assert_equal ConcernTest::Baz::ClassMethods, (class << @klass; self.included_modules; end)[0]
   end
 
+  def test_class_methods_are_extended_only_on_expected_objects
+    ::Object.__send__(:include, Qux)
+    Object.extend(Qux::ClassMethods)
+    # module needs to be created after Qux is included in Object or bug won't
+    # be triggered
+    test_module = Module.new do
+      extend ActiveSupport::Concern
+
+      class_methods do
+        def test
+        end
+      end
+    end
+    @klass.include test_module
+    assert_equal false, Object.respond_to?(:test)
+    Qux.class_eval do
+      remove_const :ClassMethods
+    end
+  end
+
   def test_included_block_is_ran
-    @klass.send(:include, Baz)
+    @klass.include(Baz)
     assert_equal true, @klass.included_ran
   end
 
   def test_modules_dependencies_are_met
-    @klass.send(:include, Bar)
+    @klass.include(Bar)
     assert_equal "bar", @klass.new.bar
     assert_equal "bar+baz", @klass.new.baz
     assert_equal "bar's baz + baz", @klass.baz
@@ -84,7 +109,7 @@ class ConcernTest < ActiveSupport::TestCase
   end
 
   def test_dependencies_with_multiple_modules
-    @klass.send(:include, Foo)
+    @klass.include(Foo)
     assert_equal [ConcernTest::Foo, ConcernTest::Bar, ConcernTest::Baz], @klass.included_modules[0..2]
   end
 
diff --git a/activesupport/test/configurable_test.rb b/activesupport/test/configurable_test.rb
index ef847fc557..5d22ded2de 100644
--- a/activesupport/test/configurable_test.rb
+++ b/activesupport/test/configurable_test.rb
@@ -111,6 +111,14 @@ class ConfigurableActiveSupport < ActiveSupport::TestCase
     end
   end
 
+  test 'the config_accessor method should not be publicly callable' do
+    assert_raises NoMethodError do
+      Class.new {
+        include ActiveSupport::Configurable
+      }.config_accessor :foo
+    end
+  end
+
   def assert_method_defined(object, method)
     methods = object.public_methods.map(&:to_s)
     assert methods.include?(method.to_s), "Expected #{methods.inspect} to include #{method.to_s.inspect}"
diff --git a/activesupport/test/constantize_test_cases.rb b/activesupport/test/constantize_test_cases.rb
index 366e4e5ef0..1115bc0fd8 100644
--- a/activesupport/test/constantize_test_cases.rb
+++ b/activesupport/test/constantize_test_cases.rb
@@ -100,6 +100,10 @@ module ConstantizeTestCases
     assert_nil yield("Ace::Gas::ConstantizeTestCases")
     assert_nil yield("#<Class:0x7b8b718b>::Nested_1")
     assert_nil yield("Ace::gas")
+    assert_nil yield('Object::ABC')
+    assert_nil yield('Object::Object::Object::ABC')
+    assert_nil yield('A::Object::B')
+    assert_nil yield('A::Object::Object::Object::B')
 
     assert_raises(NameError) do
       with_autoloading_fixtures do
diff --git a/activesupport/test/core_ext/array/access_test.rb b/activesupport/test/core_ext/array/access_test.rb
index f14f64421d..3f1e0c4cb4 100644
--- a/activesupport/test/core_ext/array/access_test.rb
+++ b/activesupport/test/core_ext/array/access_test.rb
@@ -27,4 +27,8 @@ class AccessTest < ActiveSupport::TestCase
     assert_equal array[4], array.fifth
     assert_equal array[41], array.forty_two
   end
+
+  def test_without
+    assert_equal [1, 2, 4], [1, 2, 3, 4, 5].without(3, 5)
+  end
 end
diff --git a/activesupport/test/core_ext/array/conversions_test.rb b/activesupport/test/core_ext/array/conversions_test.rb
index 577b889410..507e13f968 100644
--- a/activesupport/test/core_ext/array/conversions_test.rb
+++ b/activesupport/test/core_ext/array/conversions_test.rb
@@ -60,6 +60,12 @@ class ToSentenceTest < ActiveSupport::TestCase
 
     assert_equal exception.message, "Unknown key: :passing. Valid keys are: :words_connector, :two_words_connector, :last_word_connector, :locale"
   end
+
+  def test_always_returns_string
+    assert_instance_of String, [ActiveSupport::SafeBuffer.new('one')].to_sentence
+    assert_instance_of String, [ActiveSupport::SafeBuffer.new('one'), 'two'].to_sentence
+    assert_instance_of String, [ActiveSupport::SafeBuffer.new('one'), 'two', 'three'].to_sentence
+  end
 end
 
 class ToSTest < ActiveSupport::TestCase
diff --git a/activesupport/test/core_ext/class/delegating_attributes_test.rb b/activesupport/test/core_ext/class/delegating_attributes_test.rb
deleted file mode 100644
index 447b1d10ad..0000000000
--- a/activesupport/test/core_ext/class/delegating_attributes_test.rb
+++ /dev/null
@@ -1,122 +0,0 @@
-require 'abstract_unit'
-require 'active_support/core_ext/class/delegating_attributes'
-
-module DelegatingFixtures
-  class Parent
-  end
-
-  class Child < Parent
-    ActiveSupport::Deprecation.silence do
-      superclass_delegating_accessor :some_attribute
-    end
-  end
-
-  class Mokopuna < Child
-  end
-
-  class PercysMom
-    ActiveSupport::Deprecation.silence do
-      superclass_delegating_accessor :superpower
-    end
-  end
-
-  class Percy < PercysMom
-  end
-end
-
-class DelegatingAttributesTest < ActiveSupport::TestCase
-  include DelegatingFixtures
-  attr_reader :single_class
-
-  def setup
-    @single_class = Class.new(Object)
-  end
-
-  def test_simple_accessor_declaration
-    assert_deprecated do
-      single_class.superclass_delegating_accessor :both
-    end
-
-    # Class should have accessor and mutator
-    # the instance should have an accessor only
-    assert_respond_to single_class, :both
-    assert_respond_to single_class, :both=
-    assert single_class.public_instance_methods.map(&:to_s).include?("both")
-    assert !single_class.public_instance_methods.map(&:to_s).include?("both=")
-  end
-
-  def test_simple_accessor_declaration_with_instance_reader_false
-    _instance_methods = single_class.public_instance_methods
-
-    assert_deprecated do
-      single_class.superclass_delegating_accessor :no_instance_reader, :instance_reader => false
-    end
-
-    assert_respond_to single_class, :no_instance_reader
-    assert_respond_to single_class, :no_instance_reader=
-    assert !_instance_methods.include?(:no_instance_reader)
-    assert !_instance_methods.include?(:no_instance_reader?)
-    assert !_instance_methods.include?(:_no_instance_reader)
-  end
-
-  def test_working_with_simple_attributes
-    assert_deprecated do
-      single_class.superclass_delegating_accessor :both
-    end
-
-    single_class.both = "HMMM"
-
-    assert_equal "HMMM", single_class.both
-    assert_equal true, single_class.both?
-
-    assert_equal "HMMM", single_class.new.both
-    assert_equal true, single_class.new.both?
-
-    single_class.both = false
-    assert_equal false, single_class.both?
-  end
-
-  def test_child_class_delegates_to_parent_but_can_be_overridden
-    parent = Class.new
-
-    assert_deprecated do
-      parent.superclass_delegating_accessor :both
-    end
-
-    child = Class.new(parent)
-    parent.both = "1"
-    assert_equal "1", child.both
-
-    child.both = "2"
-    assert_equal "1", parent.both
-    assert_equal "2", child.both
-
-    parent.both = "3"
-    assert_equal "3", parent.both
-    assert_equal "2", child.both
-  end
-
-  def test_delegation_stops_at_the_right_level
-    assert_nil Percy.superpower
-    assert_nil PercysMom.superpower
-
-    PercysMom.superpower = :heatvision
-    assert_equal :heatvision, Percy.superpower
-  end
-
-  def test_delegation_stops_for_nil
-    Mokopuna.some_attribute = nil
-    Child.some_attribute="1"
-
-    assert_equal "1", Child.some_attribute
-    assert_nil Mokopuna.some_attribute
-  ensure
-    Child.some_attribute=nil
-  end
-
-  def test_deprecation_warning
-    assert_deprecated(/superclass_delegating_accessor is deprecated/) do
-      single_class.superclass_delegating_accessor :test_attribute
-    end
-  end
-end
diff --git a/activesupport/test/core_ext/date_ext_test.rb b/activesupport/test/core_ext/date_ext_test.rb
index e89be25b53..0fc3f765f5 100644
--- a/activesupport/test/core_ext/date_ext_test.rb
+++ b/activesupport/test/core_ext/date_ext_test.rb
@@ -191,8 +191,9 @@ class DateExtCalculationsTest < ActiveSupport::TestCase
   def test_yesterday_constructor_when_zone_is_set
     with_env_tz 'UTC' do
       with_tz_default ActiveSupport::TimeZone['Eastern Time (US & Canada)'] do # UTC -5
-        Time.stubs(:now).returns Time.local(2000, 1, 1)
-        assert_equal Date.new(1999, 12, 30), Date.yesterday
+        Time.stub(:now, Time.local(2000, 1, 1)) do
+          assert_equal Date.new(1999, 12, 30), Date.yesterday
+        end
       end
     end
   end
@@ -212,8 +213,9 @@ class DateExtCalculationsTest < ActiveSupport::TestCase
   def test_tomorrow_constructor_when_zone_is_set
     with_env_tz 'UTC' do
       with_tz_default ActiveSupport::TimeZone['Europe/Paris'] do # UTC +1
-        Time.stubs(:now).returns Time.local(1999, 12, 31, 23)
-        assert_equal Date.new(2000, 1, 2), Date.tomorrow
+        Time.stub(:now, Time.local(1999, 12, 31, 23)) do
+          assert_equal Date.new(2000, 1, 2), Date.tomorrow
+        end
       end
     end
   end
@@ -317,23 +319,26 @@ class DateExtCalculationsTest < ActiveSupport::TestCase
   end
 
   def test_past
-    Date.stubs(:current).returns(Date.new(2000, 1, 1))
-    assert_equal true, Date.new(1999, 12, 31).past?
-    assert_equal false, Date.new(2000,1,1).past?
-    assert_equal false, Date.new(2000,1,2).past?
+    Date.stub(:current, Date.new(2000, 1, 1)) do
+      assert_equal true, Date.new(1999, 12, 31).past?
+      assert_equal false, Date.new(2000,1,1).past?
+      assert_equal false, Date.new(2000,1,2).past?
+    end
   end
 
   def test_future
-    Date.stubs(:current).returns(Date.new(2000, 1, 1))
-    assert_equal false, Date.new(1999, 12, 31).future?
-    assert_equal false, Date.new(2000,1,1).future?
-    assert_equal true, Date.new(2000,1,2).future?
+    Date.stub(:current, Date.new(2000, 1, 1)) do
+      assert_equal false, Date.new(1999, 12, 31).future?
+      assert_equal false, Date.new(2000,1,1).future?
+      assert_equal true, Date.new(2000,1,2).future?
+    end
   end
 
   def test_current_returns_date_today_when_zone_not_set
     with_env_tz 'US/Central' do
-      Time.stubs(:now).returns Time.local(1999, 12, 31, 23)
-      assert_equal Date.today, Date.current
+      Time.stub(:now, Time.local(1999, 12, 31, 23)) do
+        assert_equal Date.today, Date.current
+      end
     end
   end
 
diff --git a/activesupport/test/core_ext/date_time_ext_test.rb b/activesupport/test/core_ext/date_time_ext_test.rb
index 74319ecd09..6fe38c45ec 100644
--- a/activesupport/test/core_ext/date_time_ext_test.rb
+++ b/activesupport/test/core_ext/date_time_ext_test.rb
@@ -204,61 +204,69 @@ class DateTimeExtCalculationsTest < ActiveSupport::TestCase
   end
 
   def test_today_with_offset
-    Date.stubs(:current).returns(Date.new(2000, 1, 1))
-    assert_equal false, DateTime.civil(1999,12,31,23,59,59, Rational(-18000, 86400)).today?
-    assert_equal true,  DateTime.civil(2000,1,1,0,0,0, Rational(-18000, 86400)).today?
-    assert_equal true,  DateTime.civil(2000,1,1,23,59,59, Rational(-18000, 86400)).today?
-    assert_equal false, DateTime.civil(2000,1,2,0,0,0, Rational(-18000, 86400)).today?
+    Date.stub(:current, Date.new(2000, 1, 1)) do
+      assert_equal false, DateTime.civil(1999,12,31,23,59,59, Rational(-18000, 86400)).today?
+      assert_equal true,  DateTime.civil(2000,1,1,0,0,0, Rational(-18000, 86400)).today?
+      assert_equal true,  DateTime.civil(2000,1,1,23,59,59, Rational(-18000, 86400)).today?
+      assert_equal false, DateTime.civil(2000,1,2,0,0,0, Rational(-18000, 86400)).today?
+    end
   end
 
   def test_today_without_offset
-    Date.stubs(:current).returns(Date.new(2000, 1, 1))
-    assert_equal false, DateTime.civil(1999,12,31,23,59,59).today?
-    assert_equal true,  DateTime.civil(2000,1,1,0).today?
-    assert_equal true,  DateTime.civil(2000,1,1,23,59,59).today?
-    assert_equal false, DateTime.civil(2000,1,2,0).today?
+    Date.stub(:current, Date.new(2000, 1, 1)) do
+      assert_equal false, DateTime.civil(1999,12,31,23,59,59).today?
+      assert_equal true,  DateTime.civil(2000,1,1,0).today?
+      assert_equal true,  DateTime.civil(2000,1,1,23,59,59).today?
+      assert_equal false, DateTime.civil(2000,1,2,0).today?
+    end
   end
 
   def test_past_with_offset
-    DateTime.stubs(:current).returns(DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400)))
-    assert_equal true,  DateTime.civil(2005,2,10,15,30,44, Rational(-18000, 86400)).past?
-    assert_equal false,  DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400)).past?
-    assert_equal false,  DateTime.civil(2005,2,10,15,30,46, Rational(-18000, 86400)).past?
+    DateTime.stub(:current, DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400))) do
+      assert_equal true,  DateTime.civil(2005,2,10,15,30,44, Rational(-18000, 86400)).past?
+      assert_equal false,  DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400)).past?
+      assert_equal false,  DateTime.civil(2005,2,10,15,30,46, Rational(-18000, 86400)).past?
+    end
   end
 
   def test_past_without_offset
-    DateTime.stubs(:current).returns(DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400)))
-    assert_equal true,  DateTime.civil(2005,2,10,20,30,44).past?
-    assert_equal false,  DateTime.civil(2005,2,10,20,30,45).past?
-    assert_equal false,  DateTime.civil(2005,2,10,20,30,46).past?
+    DateTime.stub(:current, DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400))) do
+      assert_equal true,  DateTime.civil(2005,2,10,20,30,44).past?
+      assert_equal false,  DateTime.civil(2005,2,10,20,30,45).past?
+      assert_equal false,  DateTime.civil(2005,2,10,20,30,46).past?
+    end
   end
 
   def test_future_with_offset
-    DateTime.stubs(:current).returns(DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400)))
-    assert_equal false,  DateTime.civil(2005,2,10,15,30,44, Rational(-18000, 86400)).future?
-    assert_equal false,  DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400)).future?
-    assert_equal true,  DateTime.civil(2005,2,10,15,30,46, Rational(-18000, 86400)).future?
+    DateTime.stub(:current, DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400))) do
+      assert_equal false,  DateTime.civil(2005,2,10,15,30,44, Rational(-18000, 86400)).future?
+      assert_equal false,  DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400)).future?
+      assert_equal true,  DateTime.civil(2005,2,10,15,30,46, Rational(-18000, 86400)).future?
+    end
   end
 
   def test_future_without_offset
-    DateTime.stubs(:current).returns(DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400)))
-    assert_equal false,  DateTime.civil(2005,2,10,20,30,44).future?
-    assert_equal false,  DateTime.civil(2005,2,10,20,30,45).future?
-    assert_equal true,  DateTime.civil(2005,2,10,20,30,46).future?
+    DateTime.stub(:current, DateTime.civil(2005,2,10,15,30,45, Rational(-18000, 86400))) do
+      assert_equal false,  DateTime.civil(2005,2,10,20,30,44).future?
+      assert_equal false,  DateTime.civil(2005,2,10,20,30,45).future?
+      assert_equal true,  DateTime.civil(2005,2,10,20,30,46).future?
+    end
   end
 
   def test_current_returns_date_today_when_zone_is_not_set
     with_env_tz 'US/Eastern' do
-      Time.stubs(:now).returns Time.local(1999, 12, 31, 23, 59, 59)
-      assert_equal DateTime.new(1999, 12, 31, 23, 59, 59, Rational(-18000, 86400)), DateTime.current
+      Time.stub(:now, Time.local(1999, 12, 31, 23, 59, 59)) do
+        assert_equal DateTime.new(1999, 12, 31, 23, 59, 59, Rational(-18000, 86400)), DateTime.current
+      end
     end
   end
 
   def test_current_returns_time_zone_today_when_zone_is_set
     Time.zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
     with_env_tz 'US/Eastern' do
-      Time.stubs(:now).returns Time.local(1999, 12, 31, 23, 59, 59)
-      assert_equal DateTime.new(1999, 12, 31, 23, 59, 59, Rational(-18000, 86400)), DateTime.current
+      Time.stub(:now, Time.local(1999, 12, 31, 23, 59, 59)) do
+        assert_equal DateTime.new(1999, 12, 31, 23, 59, 59, Rational(-18000, 86400)), DateTime.current
+      end
     end
   ensure
     Time.zone = nil
@@ -335,6 +343,13 @@ class DateTimeExtCalculationsTest < ActiveSupport::TestCase
     assert_equal(-1, DateTime.civil(2000) <=> ActiveSupport::TimeWithZone.new( Time.utc(2000, 1, 1, 0, 0, 1), ActiveSupport::TimeZone['UTC'] ))
   end
 
+  def test_compare_with_string
+    assert_equal   1, DateTime.civil(2000) <=> Time.utc(1999, 12, 31, 23, 59, 59).to_s
+    assert_equal   0, DateTime.civil(2000) <=> Time.utc(2000, 1, 1, 0, 0, 0).to_s
+    assert_equal( -1, DateTime.civil(2000) <=> Time.utc(2000, 1, 1, 0, 0, 1).to_s)
+    assert_equal nil, DateTime.civil(2000) <=> "Invalid as Time"
+  end
+
   def test_to_f
     assert_equal 946684800.0, DateTime.civil(2000).to_f
     assert_equal 946684800.0, DateTime.civil(1999,12,31,19,0,0,Rational(-5,24)).to_f
diff --git a/activesupport/test/core_ext/duration_test.rb b/activesupport/test/core_ext/duration_test.rb
index c283b546e6..9e97acaffb 100644
--- a/activesupport/test/core_ext/duration_test.rb
+++ b/activesupport/test/core_ext/duration_test.rb
@@ -140,28 +140,30 @@ class DurationTest < ActiveSupport::TestCase
   def test_since_and_ago_anchored_to_time_now_when_time_zone_is_not_set
     Time.zone = nil
     with_env_tz 'US/Eastern' do
-      Time.stubs(:now).returns Time.local(2000)
-      # since
-      assert_not_instance_of ActiveSupport::TimeWithZone, 5.seconds.since
-      assert_equal Time.local(2000,1,1,0,0,5), 5.seconds.since
-      # ago
-      assert_not_instance_of ActiveSupport::TimeWithZone, 5.seconds.ago
-      assert_equal Time.local(1999,12,31,23,59,55), 5.seconds.ago
+      Time.stub(:now, Time.local(2000)) do
+        # since
+        assert_not_instance_of ActiveSupport::TimeWithZone, 5.seconds.since
+        assert_equal Time.local(2000,1,1,0,0,5), 5.seconds.since
+        # ago
+        assert_not_instance_of ActiveSupport::TimeWithZone, 5.seconds.ago
+        assert_equal Time.local(1999,12,31,23,59,55), 5.seconds.ago
+      end
     end
   end
 
   def test_since_and_ago_anchored_to_time_zone_now_when_time_zone_is_set
     Time.zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
     with_env_tz 'US/Eastern' do
-      Time.stubs(:now).returns Time.local(2000)
-      # since
-      assert_instance_of ActiveSupport::TimeWithZone, 5.seconds.since
-      assert_equal Time.utc(2000,1,1,0,0,5), 5.seconds.since.time
-      assert_equal 'Eastern Time (US & Canada)', 5.seconds.since.time_zone.name
-      # ago
-      assert_instance_of ActiveSupport::TimeWithZone, 5.seconds.ago
-      assert_equal Time.utc(1999,12,31,23,59,55), 5.seconds.ago.time
-      assert_equal 'Eastern Time (US & Canada)', 5.seconds.ago.time_zone.name
+      Time.stub(:now, Time.local(2000)) do
+        # since
+        assert_instance_of ActiveSupport::TimeWithZone, 5.seconds.since
+        assert_equal Time.utc(2000,1,1,0,0,5), 5.seconds.since.time
+        assert_equal 'Eastern Time (US & Canada)', 5.seconds.since.time_zone.name
+        # ago
+        assert_instance_of ActiveSupport::TimeWithZone, 5.seconds.ago
+        assert_equal Time.utc(1999,12,31,23,59,55), 5.seconds.ago.time
+        assert_equal 'Eastern Time (US & Canada)', 5.seconds.ago.time_zone.name
+      end
     end
   ensure
     Time.zone = nil
diff --git a/activesupport/test/core_ext/enumerable_test.rb b/activesupport/test/core_ext/enumerable_test.rb
index 346dc3d208..f09b7d8850 100644
--- a/activesupport/test/core_ext/enumerable_test.rb
+++ b/activesupport/test/core_ext/enumerable_test.rb
@@ -3,6 +3,8 @@ require 'active_support/core_ext/array'
 require 'active_support/core_ext/enumerable'
 
 Payment = Struct.new(:price)
+ExpandedPayment = Struct.new(:dollars, :cents)
+
 class SummablePayment < Payment
   def +(p) self.class.new(price + p.price) end
 end
@@ -103,4 +105,23 @@ class EnumerableTests < ActiveSupport::TestCase
     assert_equal true,  GenericEnumerable.new([ 1 ]).exclude?(2)
     assert_equal false, GenericEnumerable.new([ 1 ]).exclude?(1)
   end
+
+  def test_without
+    assert_equal [1, 2, 4], GenericEnumerable.new((1..5).to_a).without(3, 5)
+    assert_equal [1, 2, 4], (1..5).to_a.without(3, 5)
+    assert_equal [1, 2, 4], (1..5).to_set.without(3, 5)
+    assert_equal({foo: 1, baz: 3}, {foo: 1, bar: 2, baz: 3}.without(:bar))
+  end
+
+  def test_pluck
+    payments = GenericEnumerable.new([ Payment.new(5), Payment.new(15), Payment.new(10) ])
+    assert_equal [5, 15, 10], payments.pluck(:price)
+
+    payments = GenericEnumerable.new([
+      ExpandedPayment.new(5, 99),
+      ExpandedPayment.new(15, 0),
+      ExpandedPayment.new(10, 50)
+    ])
+    assert_equal [[5, 99], [15, 0], [10, 50]], payments.pluck(:dollars, :cents)
+  end
 end
diff --git a/activesupport/test/core_ext/file_test.rb b/activesupport/test/core_ext/file_test.rb
index 2c04e9687c..cde0132b97 100644
--- a/activesupport/test/core_ext/file_test.rb
+++ b/activesupport/test/core_ext/file_test.rb
@@ -57,6 +57,16 @@ class AtomicWriteTest < ActiveSupport::TestCase
     File.unlink(file_name) rescue nil
   end
 
+  def test_atomic_write_returns_result_from_yielded_block
+    block_return_value = File.atomic_write(file_name, Dir.pwd) do |file|
+      "Hello world!"
+    end
+
+    assert_equal "Hello world!", block_return_value
+  ensure
+    File.unlink(file_name) rescue nil
+  end
+
   private
     def file_name
       "atomic.file"
diff --git a/activesupport/test/core_ext/hash/transform_keys_test.rb b/activesupport/test/core_ext/hash/transform_keys_test.rb
index a7e12117f3..5a0b99e22c 100644
--- a/activesupport/test/core_ext/hash/transform_keys_test.rb
+++ b/activesupport/test/core_ext/hash/transform_keys_test.rb
@@ -24,9 +24,21 @@ class TransformKeysTest < ActiveSupport::TestCase
     assert_equal Enumerator, enumerator.class
   end
 
+  test "transform_keys! returns an Enumerator if no block is given" do
+    original = { a: 'a', b: 'b' }
+    enumerator = original.transform_keys!
+    assert_equal Enumerator, enumerator.class
+  end
+
   test "transform_keys is chainable with Enumerable methods" do
     original = { a: 'a', b: 'b' }
     mapped = original.transform_keys.with_index { |k, i| [k, i].join.to_sym }
     assert_equal({ a0: 'a', b1: 'b' }, mapped)
   end
+
+  test "transform_keys! is chainable with Enumerable methods" do
+    original = { a: 'a', b: 'b' }
+    original.transform_keys!.with_index { |k, i| [k, i].join.to_sym }
+    assert_equal({ a0: 'a', b1: 'b' }, original)
+  end
 end
diff --git a/activesupport/test/core_ext/hash/transform_values_test.rb b/activesupport/test/core_ext/hash/transform_values_test.rb
index 45ed11fef7..7c33227dc0 100644
--- a/activesupport/test/core_ext/hash/transform_values_test.rb
+++ b/activesupport/test/core_ext/hash/transform_values_test.rb
@@ -53,9 +53,21 @@ class TransformValuesTest < ActiveSupport::TestCase
     assert_equal Enumerator, enumerator.class
   end
 
+  test "transform_values! returns an Enumerator if no block is given" do
+    original = { a: 'a', b: 'b' }
+    enumerator = original.transform_values!
+    assert_equal Enumerator, enumerator.class
+  end
+
   test "transform_values is chainable with Enumerable methods" do
     original = { a: 'a', b: 'b' }
     mapped = original.transform_values.with_index { |v, i| [v, i].join }
     assert_equal({ a: 'a0', b: 'b1' }, mapped)
   end
+
+  test "transform_values! is chainable with Enumerable methods" do
+    original = { a: 'a', b: 'b' }
+    original.transform_values!.with_index { |v, i| [v, i].join }
+    assert_equal({ a: 'a0', b: 'b1' }, original)
+  end
 end
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index 3d2f50ce49..4624338df1 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -524,6 +524,10 @@ class HashExtTest < ActiveSupport::TestCase
   end
 
   def test_indifferent_reverse_merging
+    hash = HashWithIndifferentAccess.new key: :old_value
+    hash.reverse_merge! key: :new_value
+    assert_equal :old_value, hash[:key]
+
     hash = HashWithIndifferentAccess.new('some' => 'value', 'other' => 'value')
     hash.reverse_merge!(:some => 'noclobber', :another => 'clobber')
     assert_equal 'value', hash[:some]
@@ -547,6 +551,11 @@ class HashExtTest < ActiveSupport::TestCase
     assert_instance_of ActiveSupport::HashWithIndifferentAccess, hash
   end
 
+  def test_indifferent_select_returns_enumerator
+    enum = ActiveSupport::HashWithIndifferentAccess.new(@strings).select
+    assert_instance_of Enumerator, enum
+  end
+
   def test_indifferent_select_returns_a_hash_when_unchanged
     hash = ActiveSupport::HashWithIndifferentAccess.new(@strings).select {|k,v| true}
 
@@ -568,6 +577,11 @@ class HashExtTest < ActiveSupport::TestCase
     assert_instance_of ActiveSupport::HashWithIndifferentAccess, hash
   end
 
+  def test_indifferent_reject_returns_enumerator
+    enum = ActiveSupport::HashWithIndifferentAccess.new(@strings).reject
+    assert_instance_of Enumerator, enum
+  end
+
   def test_indifferent_reject_bang
     indifferent_strings = ActiveSupport::HashWithIndifferentAccess.new(@strings)
     indifferent_strings.reject! {|k,v| v != 1}
@@ -961,10 +975,11 @@ class HashExtTest < ActiveSupport::TestCase
     assert_raise(RuntimeError) { original.except!(:a) }
   end
 
-  def test_except_with_mocha_expectation_on_original
+  def test_except_does_not_delete_values_in_original
     original = { :a => 'x', :b => 'y' }
-    original.expects(:delete).never
-    original.except(:a)
+    assert_not_called(original, :delete) do
+      original.except(:a)
+    end
   end
 
   def test_compact
@@ -998,6 +1013,37 @@ class HashExtTest < ActiveSupport::TestCase
     assert hash.key?('a')
     assert_equal 1, hash[:a]
   end
+
+  def test_dup_with_default_proc
+    hash = HashWithIndifferentAccess.new
+    hash.default_proc = proc { |h, v| raise "walrus" }
+    assert_nothing_raised { hash.dup }
+  end
+
+  def test_dup_with_default_proc_sets_proc
+    hash = HashWithIndifferentAccess.new
+    hash.default_proc = proc { |h, k| k + 1 }
+    new_hash = hash.dup
+
+    assert_equal 3, new_hash[2]
+
+    new_hash.default = 2
+    assert_equal 2, new_hash[:non_existant]
+  end
+
+  def test_to_hash_with_raising_default_proc
+    hash = HashWithIndifferentAccess.new
+    hash.default_proc = proc { |h, k| raise "walrus" }
+
+    assert_nothing_raised { hash.to_hash }
+  end
+
+  def test_new_from_hash_copying_default_should_not_raise_when_default_proc_does
+    hash = Hash.new
+    hash.default_proc = proc { |h, k| raise "walrus" }
+
+    assert_nothing_raised { HashWithIndifferentAccess.new_from_hash_copying_default(hash) }
+  end
 end
 
 class IWriteMyOwnXML
@@ -1549,6 +1595,14 @@ class HashToXmlTest < ActiveSupport::TestCase
     assert_not_same hash_wia, hash_wia.with_indifferent_access
   end
 
+
+  def test_allows_setting_frozen_array_values_with_indifferent_access
+    value = [1, 2, 3].freeze
+    hash = HashWithIndifferentAccess.new
+    hash[:key] = value
+    assert_equal hash[:key], value
+  end
+
   def test_should_copy_the_default_value_when_converting_to_hash_with_indifferent_access
     hash = Hash.new(3)
     hash_wia = hash.with_indifferent_access
diff --git a/activesupport/test/core_ext/marshal_test.rb b/activesupport/test/core_ext/marshal_test.rb
index 8f3f710dfd..825df439a5 100644
--- a/activesupport/test/core_ext/marshal_test.rb
+++ b/activesupport/test/core_ext/marshal_test.rb
@@ -8,28 +8,28 @@ class MarshalTest < ActiveSupport::TestCase
 
   def teardown
     ActiveSupport::Dependencies.clear
-    remove_constants(:E, :ClassFolder)
+    remove_constants(:EM, :ClassFolder)
   end
 
   test "that Marshal#load still works" do
     sanity_data = ["test", [1, 2, 3], {a: [1, 2, 3]}, ActiveSupport::TestCase]
     sanity_data.each do |obj|
       dumped = Marshal.dump(obj)
-      assert_equal Marshal.load_without_autoloading(dumped), Marshal.load(dumped)
+      assert_equal Marshal.method(:load).super_method.call(dumped), Marshal.load(dumped)
     end
   end
 
   test "that a missing class is autoloaded from string" do
     dumped = nil
     with_autoloading_fixtures do
-      dumped = Marshal.dump(E.new)
+      dumped = Marshal.dump(EM.new)
     end
 
-    remove_constants(:E)
+    remove_constants(:EM)
     ActiveSupport::Dependencies.clear
 
     with_autoloading_fixtures do
-      assert_kind_of E, Marshal.load(dumped)
+      assert_kind_of EM, Marshal.load(dumped)
     end
   end
 
@@ -50,16 +50,16 @@ class MarshalTest < ActiveSupport::TestCase
   test "that more than one missing class is autoloaded" do
     dumped = nil
     with_autoloading_fixtures do
-      dumped = Marshal.dump([E.new, ClassFolder.new])
+      dumped = Marshal.dump([EM.new, ClassFolder.new])
     end
 
-    remove_constants(:E, :ClassFolder)
+    remove_constants(:EM, :ClassFolder)
     ActiveSupport::Dependencies.clear
 
     with_autoloading_fixtures do
       loaded = Marshal.load(dumped)
       assert_equal 2, loaded.size
-      assert_kind_of E, loaded[0]
+      assert_kind_of EM, loaded[0]
       assert_kind_of ClassFolder, loaded[1]
     end
   end
@@ -67,10 +67,10 @@ class MarshalTest < ActiveSupport::TestCase
   test "that a real missing class is causing an exception" do
     dumped = nil
     with_autoloading_fixtures do
-      dumped = Marshal.dump(E.new)
+      dumped = Marshal.dump(EM.new)
     end
 
-    remove_constants(:E)
+    remove_constants(:EM)
     ActiveSupport::Dependencies.clear
 
     assert_raise(NameError) do
@@ -84,10 +84,10 @@ class MarshalTest < ActiveSupport::TestCase
     end
 
     with_autoloading_fixtures do
-      dumped = Marshal.dump([E.new, SomeClass.new])
+      dumped = Marshal.dump([EM.new, SomeClass.new])
     end
 
-    remove_constants(:E)
+    remove_constants(:EM)
     self.class.send(:remove_const, :SomeClass)
     ActiveSupport::Dependencies.clear
 
@@ -96,8 +96,8 @@ class MarshalTest < ActiveSupport::TestCase
         Marshal.load(dumped)
       end
 
-      assert_nothing_raised("E failed to load while we expect only SomeClass to fail loading") do
-        E.new
+      assert_nothing_raised("EM failed to load while we expect only SomeClass to fail loading") do
+        EM.new
       end
 
       assert_raise(NameError, "We expected SomeClass to not be loaded but it is!") do
@@ -109,16 +109,16 @@ class MarshalTest < ActiveSupport::TestCase
   test "loading classes from files trigger autoloading" do
     Tempfile.open("object_serializer_test") do |f|
       with_autoloading_fixtures do
-        Marshal.dump(E.new, f)
+        Marshal.dump(EM.new, f)
       end
 
       f.rewind
-      remove_constants(:E)
+      remove_constants(:EM)
       ActiveSupport::Dependencies.clear
 
       with_autoloading_fixtures do
-        assert_kind_of E, Marshal.load(f)
+        assert_kind_of EM, Marshal.load(f)
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/activesupport/test/core_ext/module/attribute_accessor_test.rb b/activesupport/test/core_ext/module/attribute_accessor_test.rb
index 48f3cc579f..0b0f3a2808 100644
--- a/activesupport/test/core_ext/module/attribute_accessor_test.rb
+++ b/activesupport/test/core_ext/module/attribute_accessor_test.rb
@@ -69,6 +69,20 @@ class ModuleAttributeAccessorTest < ActiveSupport::TestCase
       end
     end
     assert_equal "invalid attribute name: 1nvalid", exception.message
+
+    exception = assert_raises NameError do
+      Class.new do
+        mattr_reader "valid_part\ninvalid_part"
+      end
+    end
+    assert_equal "invalid attribute name: valid_part\ninvalid_part", exception.message
+
+    exception = assert_raises NameError do
+      Class.new do
+        mattr_writer "valid_part\ninvalid_part"
+      end
+    end
+    assert_equal "invalid attribute name: valid_part\ninvalid_part", exception.message
   end
 
   def test_should_use_default_value_if_block_passed
@@ -76,4 +90,10 @@ class ModuleAttributeAccessorTest < ActiveSupport::TestCase
     assert_equal 'default_reader_value', @module.defr
     assert_equal 'default_writer_value', @module.class_variable_get('@@defw')
   end
+
+  def test_should_not_invoke_default_value_block_multiple_times
+    count = 0
+    @module.cattr_accessor(:defcount){ count += 1 }
+    assert_equal 1, count
+  end
 end
diff --git a/activesupport/test/core_ext/module/remove_method_test.rb b/activesupport/test/core_ext/module/remove_method_test.rb
index 4657f0c175..0d684dc70e 100644
--- a/activesupport/test/core_ext/module/remove_method_test.rb
+++ b/activesupport/test/core_ext/module/remove_method_test.rb
@@ -6,24 +6,54 @@ module RemoveMethodTests
     def do_something
       return 1
     end
-    
+
+    def do_something_protected
+      return 1
+    end
+    protected :do_something_protected
+
+    def do_something_private
+      return 1
+    end
+    private :do_something_private
+
+    class << self
+      def do_something_else
+        return 2
+      end
+    end
   end
 end
 
 class RemoveMethodTest < ActiveSupport::TestCase
-  
+
   def test_remove_method_from_an_object
     RemoveMethodTests::A.class_eval{
       self.remove_possible_method(:do_something)
     }
     assert !RemoveMethodTests::A.new.respond_to?(:do_something)
   end
-  
+
+  def test_remove_singleton_method_from_an_object
+    RemoveMethodTests::A.class_eval{
+      self.remove_possible_singleton_method(:do_something_else)
+    }
+    assert !RemoveMethodTests::A.respond_to?(:do_something_else)
+  end
+
   def test_redefine_method_in_an_object
     RemoveMethodTests::A.class_eval{
       self.redefine_method(:do_something) { return 100 }
+      self.redefine_method(:do_something_protected) { return 100 }
+      self.redefine_method(:do_something_private) { return 100 }
     }
     assert_equal 100, RemoveMethodTests::A.new.do_something
+    assert_equal 100, RemoveMethodTests::A.new.send(:do_something_protected)
+    assert_equal 100, RemoveMethodTests::A.new.send(:do_something_private)
+
+    assert RemoveMethodTests::A.public_method_defined? :do_something
+    assert RemoveMethodTests::A.protected_method_defined? :do_something_protected
+    assert RemoveMethodTests::A.private_method_defined? :do_something_private
   end
 
-end
\ No newline at end of file
+end
diff --git a/activesupport/test/core_ext/module_test.rb b/activesupport/test/core_ext/module_test.rb
index 3c49c4d14f..0ed66f8c37 100644
--- a/activesupport/test/core_ext/module_test.rb
+++ b/activesupport/test/core_ext/module_test.rb
@@ -78,11 +78,21 @@ Product = Struct.new(:name) do
 
   def type
     @type ||= begin
-      :thing_without_same_method_name_as_delegated.name
+      nil.type_name
     end
   end
 end
 
+class Block
+  def hello?
+    true
+  end
+end
+
+HasBlock = Struct.new(:block) do
+  delegate :hello?, to: :block
+end
+
 class ParameterSet
   delegate :[], :[]=, :to => :@params
 
@@ -301,6 +311,11 @@ class ModuleTest < ActiveSupport::TestCase
     assert_raise(NoMethodError) { product.type_name }
   end
 
+  def test_delegation_with_method_arguments
+    has_block = HasBlock.new(Block.new)
+    assert has_block.hello?
+  end
+
   def test_parent
     assert_equal Yz::Zy, Yz::Zy::Cd.parent
     assert_equal Yz, Yz::Zy.parent
@@ -358,148 +373,178 @@ class MethodAliasingTest < ActiveSupport::TestCase
     Object.instance_eval { remove_const :FooClassWithBarMethod }
   end
 
-  def test_alias_method_chain
-    assert @instance.respond_to?(:bar)
-    feature_aliases = [:bar_with_baz, :bar_without_baz]
+  def test_alias_method_chain_deprecated
+    assert_deprecated(/alias_method_chain/) do
+      Module.new do
+        def base
+        end
+
+        def base_with_deprecated
+        end
 
-    feature_aliases.each do |method|
-      assert !@instance.respond_to?(method)
+        alias_method_chain :base, :deprecated
+      end
     end
+  end
 
-    assert_equal 'bar', @instance.bar
+  def test_alias_method_chain
+    assert_deprecated(/alias_method_chain/) do
+      assert @instance.respond_to?(:bar)
+      feature_aliases = [:bar_with_baz, :bar_without_baz]
+
+      feature_aliases.each do |method|
+        assert !@instance.respond_to?(method)
+      end
 
-    FooClassWithBarMethod.class_eval { include BarMethodAliaser }
+      assert_equal 'bar', @instance.bar
 
-    feature_aliases.each do |method|
-      assert_respond_to @instance, method
-    end
+      FooClassWithBarMethod.class_eval { include BarMethodAliaser }
 
-    assert_equal 'bar_with_baz', @instance.bar
-    assert_equal 'bar', @instance.bar_without_baz
+      feature_aliases.each do |method|
+        assert_respond_to @instance, method
+      end
+
+      assert_equal 'bar_with_baz', @instance.bar
+      assert_equal 'bar', @instance.bar_without_baz
+    end
   end
 
   def test_alias_method_chain_with_punctuation_method
-    FooClassWithBarMethod.class_eval do
-      def quux!; 'quux' end
-    end
+    assert_deprecated(/alias_method_chain/) do
+      FooClassWithBarMethod.class_eval do
+        def quux!; 'quux' end
+      end
 
-    assert !@instance.respond_to?(:quux_with_baz!)
-    FooClassWithBarMethod.class_eval do
-      include BarMethodAliaser
-      alias_method_chain :quux!, :baz
-    end
-    assert_respond_to @instance, :quux_with_baz!
+      assert !@instance.respond_to?(:quux_with_baz!)
+      FooClassWithBarMethod.class_eval do
+        include BarMethodAliaser
+        alias_method_chain :quux!, :baz
+      end
+      assert_respond_to @instance, :quux_with_baz!
 
-    assert_equal 'quux_with_baz', @instance.quux!
-    assert_equal 'quux', @instance.quux_without_baz!
+      assert_equal 'quux_with_baz', @instance.quux!
+      assert_equal 'quux', @instance.quux_without_baz!
+    end
   end
 
   def test_alias_method_chain_with_same_names_between_predicates_and_bang_methods
-    FooClassWithBarMethod.class_eval do
-      def quux!; 'quux!' end
-      def quux?; true end
-      def quux=(v); 'quux=' end
-    end
+    assert_deprecated(/alias_method_chain/) do
+      FooClassWithBarMethod.class_eval do
+        def quux!; 'quux!' end
+        def quux?; true end
+        def quux=(v); 'quux=' end
+      end
 
-    assert !@instance.respond_to?(:quux_with_baz!)
-    assert !@instance.respond_to?(:quux_with_baz?)
-    assert !@instance.respond_to?(:quux_with_baz=)
+      assert !@instance.respond_to?(:quux_with_baz!)
+      assert !@instance.respond_to?(:quux_with_baz?)
+      assert !@instance.respond_to?(:quux_with_baz=)
 
-    FooClassWithBarMethod.class_eval { include BarMethodAliaser }
-    assert_respond_to @instance, :quux_with_baz!
-    assert_respond_to @instance, :quux_with_baz?
-    assert_respond_to @instance, :quux_with_baz=
+      FooClassWithBarMethod.class_eval { include BarMethodAliaser }
+      assert_respond_to @instance, :quux_with_baz!
+      assert_respond_to @instance, :quux_with_baz?
+      assert_respond_to @instance, :quux_with_baz=
 
 
-    FooClassWithBarMethod.alias_method_chain :quux!, :baz
-    assert_equal 'quux!_with_baz', @instance.quux!
-    assert_equal 'quux!', @instance.quux_without_baz!
+      FooClassWithBarMethod.alias_method_chain :quux!, :baz
+      assert_equal 'quux!_with_baz', @instance.quux!
+      assert_equal 'quux!', @instance.quux_without_baz!
 
-    FooClassWithBarMethod.alias_method_chain :quux?, :baz
-    assert_equal false, @instance.quux?
-    assert_equal true,  @instance.quux_without_baz?
+      FooClassWithBarMethod.alias_method_chain :quux?, :baz
+      assert_equal false, @instance.quux?
+      assert_equal true,  @instance.quux_without_baz?
 
-    FooClassWithBarMethod.alias_method_chain :quux=, :baz
-    assert_equal 'quux=_with_baz', @instance.send(:quux=, 1234)
-    assert_equal 'quux=', @instance.send(:quux_without_baz=, 1234)
+      FooClassWithBarMethod.alias_method_chain :quux=, :baz
+      assert_equal 'quux=_with_baz', @instance.send(:quux=, 1234)
+      assert_equal 'quux=', @instance.send(:quux_without_baz=, 1234)
+    end
   end
 
   def test_alias_method_chain_with_feature_punctuation
-    FooClassWithBarMethod.class_eval do
-      def quux; 'quux' end
-      def quux?; 'quux?' end
-      include BarMethodAliaser
-      alias_method_chain :quux, :baz!
-    end
+    assert_deprecated(/alias_method_chain/) do
+      FooClassWithBarMethod.class_eval do
+        def quux; 'quux' end
+        def quux?; 'quux?' end
+        include BarMethodAliaser
+        alias_method_chain :quux, :baz!
+      end
 
-    assert_nothing_raised do
-      assert_equal 'quux_with_baz', @instance.quux_with_baz!
-    end
+      assert_nothing_raised do
+        assert_equal 'quux_with_baz', @instance.quux_with_baz!
+      end
 
-    assert_raise(NameError) do
-      FooClassWithBarMethod.alias_method_chain :quux?, :baz!
+      assert_raise(NameError) do
+        FooClassWithBarMethod.alias_method_chain :quux?, :baz!
+      end
     end
   end
 
   def test_alias_method_chain_yields_target_and_punctuation
-    args = nil
+    assert_deprecated(/alias_method_chain/) do
+      args = nil
 
-    FooClassWithBarMethod.class_eval do
-      def quux?; end
-      include BarMethods
+      FooClassWithBarMethod.class_eval do
+        def quux?; end
+        include BarMethods
 
-      FooClassWithBarMethod.alias_method_chain :quux?, :baz do |target, punctuation|
-        args = [target, punctuation]
+        FooClassWithBarMethod.alias_method_chain :quux?, :baz do |target, punctuation|
+          args = [target, punctuation]
+        end
       end
-    end
 
-    assert_not_nil args
-    assert_equal 'quux', args[0]
-    assert_equal '?', args[1]
+      assert_not_nil args
+      assert_equal 'quux', args[0]
+      assert_equal '?', args[1]
+    end
   end
 
   def test_alias_method_chain_preserves_private_method_status
-    FooClassWithBarMethod.class_eval do
-      def duck; 'duck' end
-      include BarMethodAliaser
-      private :duck
-      alias_method_chain :duck, :orange
-    end
+    assert_deprecated(/alias_method_chain/) do
+      FooClassWithBarMethod.class_eval do
+        def duck; 'duck' end
+        include BarMethodAliaser
+        private :duck
+        alias_method_chain :duck, :orange
+      end
 
-    assert_raise NoMethodError do
-      @instance.duck
-    end
+      assert_raise NoMethodError do
+        @instance.duck
+      end
 
-    assert_equal 'duck_with_orange', @instance.instance_eval { duck }
-    assert FooClassWithBarMethod.private_method_defined?(:duck)
+      assert_equal 'duck_with_orange', @instance.instance_eval { duck }
+      assert FooClassWithBarMethod.private_method_defined?(:duck)
+    end
   end
 
   def test_alias_method_chain_preserves_protected_method_status
-    FooClassWithBarMethod.class_eval do
-      def duck; 'duck' end
-      include BarMethodAliaser
-      protected :duck
-      alias_method_chain :duck, :orange
-    end
+    assert_deprecated(/alias_method_chain/) do
+      FooClassWithBarMethod.class_eval do
+        def duck; 'duck' end
+        include BarMethodAliaser
+        protected :duck
+        alias_method_chain :duck, :orange
+      end
 
-    assert_raise NoMethodError do
-      @instance.duck
-    end
+      assert_raise NoMethodError do
+        @instance.duck
+      end
 
-    assert_equal 'duck_with_orange', @instance.instance_eval { duck }
-    assert FooClassWithBarMethod.protected_method_defined?(:duck)
+      assert_equal 'duck_with_orange', @instance.instance_eval { duck }
+      assert FooClassWithBarMethod.protected_method_defined?(:duck)
+    end
   end
 
   def test_alias_method_chain_preserves_public_method_status
-    FooClassWithBarMethod.class_eval do
-      def duck; 'duck' end
-      include BarMethodAliaser
-      public :duck
-      alias_method_chain :duck, :orange
-    end
+    assert_deprecated(/alias_method_chain/) do
+      FooClassWithBarMethod.class_eval do
+        def duck; 'duck' end
+        include BarMethodAliaser
+        public :duck
+        alias_method_chain :duck, :orange
+      end
 
-    assert_equal 'duck_with_orange', @instance.duck
-    assert FooClassWithBarMethod.public_method_defined?(:duck)
+      assert_equal 'duck_with_orange', @instance.duck
+      assert FooClassWithBarMethod.public_method_defined?(:duck)
+    end
   end
 
   def test_delegate_with_case
diff --git a/activesupport/test/core_ext/numeric_ext_test.rb b/activesupport/test/core_ext/numeric_ext_test.rb
index b82448458d..0ff8f0f89b 100644
--- a/activesupport/test/core_ext/numeric_ext_test.rb
+++ b/activesupport/test/core_ext/numeric_ext_test.rb
@@ -280,14 +280,16 @@ class NumericExtFormattingTest < ActiveSupport::TestCase
   end
 
   def test_to_s__human_size_with_si_prefix
-    assert_equal '3 Bytes',    3.14159265.to_s(:human_size, :prefix => :si)
-    assert_equal '123 Bytes',  123.0.to_s(:human_size, :prefix => :si)
-    assert_equal '123 Bytes',  123.to_s(:human_size, :prefix => :si)
-    assert_equal '1.23 KB',    1234.to_s(:human_size, :prefix => :si)
-    assert_equal '12.3 KB',    12345.to_s(:human_size, :prefix => :si)
-    assert_equal '1.23 MB',    1234567.to_s(:human_size, :prefix => :si)
-    assert_equal '1.23 GB',    1234567890.to_s(:human_size, :prefix => :si)
-    assert_equal '1.23 TB',    1234567890123.to_s(:human_size, :prefix => :si)
+    assert_deprecated do
+      assert_equal '3 Bytes',    3.14159265.to_s(:human_size, :prefix => :si)
+      assert_equal '123 Bytes',  123.0.to_s(:human_size, :prefix => :si)
+      assert_equal '123 Bytes',  123.to_s(:human_size, :prefix => :si)
+      assert_equal '1.23 KB',    1234.to_s(:human_size, :prefix => :si)
+      assert_equal '12.3 KB',    12345.to_s(:human_size, :prefix => :si)
+      assert_equal '1.23 MB',    1234567.to_s(:human_size, :prefix => :si)
+      assert_equal '1.23 GB',    1234567890.to_s(:human_size, :prefix => :si)
+      assert_equal '1.23 TB',    1234567890123.to_s(:human_size, :prefix => :si)
+    end
   end
 
   def test_to_s__human_size_with_options_hash
@@ -389,4 +391,88 @@ class NumericExtFormattingTest < ActiveSupport::TestCase
   def test_in_milliseconds
     assert_equal 10_000, 10.seconds.in_milliseconds
   end
+
+  # TODO: Remove positive and negative tests when we drop support to ruby < 2.3
+  b = 2**64
+  b *= b until Bignum === b
+
+  T_ZERO = b.coerce(0).first
+  T_ONE  = b.coerce(1).first
+  T_MONE = b.coerce(-1).first
+
+  def test_positive
+    assert_predicate(1, :positive?)
+    assert_not_predicate(0, :positive?)
+    assert_not_predicate(-1, :positive?)
+    assert_predicate(+1.0, :positive?)
+    assert_not_predicate(+0.0, :positive?)
+    assert_not_predicate(-0.0, :positive?)
+    assert_not_predicate(-1.0, :positive?)
+    assert_predicate(+(0.0.next_float), :positive?)
+    assert_not_predicate(-(0.0.next_float), :positive?)
+    assert_predicate(Float::INFINITY, :positive?)
+    assert_not_predicate(-Float::INFINITY, :positive?)
+    assert_not_predicate(Float::NAN, :positive?)
+
+    a = Class.new(Numeric) do
+      def >(x); true; end
+    end.new
+    assert_predicate(a, :positive?)
+
+    a = Class.new(Numeric) do
+      def >(x); false; end
+    end.new
+    assert_not_predicate(a, :positive?)
+
+    assert_predicate(1/2r, :positive?)
+    assert_not_predicate(-1/2r, :positive?)
+
+    assert_predicate(T_ONE, :positive?)
+    assert_not_predicate(T_MONE, :positive?)
+    assert_not_predicate(T_ZERO, :positive?)
+
+    e = assert_raises(NoMethodError) do
+      Complex(1).positive?
+    end
+
+    assert_match(/positive\?/, e.message)
+  end
+
+  def test_negative
+    assert_predicate(-1, :negative?)
+    assert_not_predicate(0, :negative?)
+    assert_not_predicate(1, :negative?)
+    assert_predicate(-1.0, :negative?)
+    assert_not_predicate(-0.0, :negative?)
+    assert_not_predicate(+0.0, :negative?)
+    assert_not_predicate(+1.0, :negative?)
+    assert_predicate(-(0.0.next_float), :negative?)
+    assert_not_predicate(+(0.0.next_float), :negative?)
+    assert_predicate(-Float::INFINITY, :negative?)
+    assert_not_predicate(Float::INFINITY, :negative?)
+    assert_not_predicate(Float::NAN, :negative?)
+
+    a = Class.new(Numeric) do
+      def <(x); true; end
+    end.new
+    assert_predicate(a, :negative?)
+
+    a = Class.new(Numeric) do
+      def <(x); false; end
+    end.new
+    assert_not_predicate(a, :negative?)
+
+    assert_predicate(-1/2r, :negative?)
+    assert_not_predicate(1/2r, :negative?)
+
+    assert_not_predicate(T_ONE, :negative?)
+    assert_predicate(T_MONE, :negative?)
+    assert_not_predicate(T_ZERO, :negative?)
+
+    e = assert_raises(NoMethodError) do
+      Complex(1).negative?
+    end
+
+    assert_match(/negative\?/, e.message)
+  end
 end
diff --git a/activesupport/test/core_ext/object/blank_test.rb b/activesupport/test/core_ext/object/blank_test.rb
index 246bc7fa61..a142096993 100644
--- a/activesupport/test/core_ext/object/blank_test.rb
+++ b/activesupport/test/core_ext/object/blank_test.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 require 'abstract_unit'
 require 'active_support/core_ext/object/blank'
 
diff --git a/activesupport/test/core_ext/object/deep_dup_test.rb b/activesupport/test/core_ext/object/deep_dup_test.rb
index 91d558dbb5..791b5e7172 100644
--- a/activesupport/test/core_ext/object/deep_dup_test.rb
+++ b/activesupport/test/core_ext/object/deep_dup_test.rb
@@ -50,4 +50,10 @@ class DeepDupTest < ActiveSupport::TestCase
     assert dup.instance_variable_defined?(:@a)
   end
 
+  def test_deep_dup_with_hash_class_key
+    hash = { Fixnum => 1 }
+    dup = hash.deep_dup
+    assert_equal 1, dup.keys.length
+  end
+
 end
diff --git a/activesupport/test/core_ext/object/duplicable_test.rb b/activesupport/test/core_ext/object/duplicable_test.rb
index d37f4bd0d8..042f5cfb34 100644
--- a/activesupport/test/core_ext/object/duplicable_test.rb
+++ b/activesupport/test/core_ext/object/duplicable_test.rb
@@ -9,6 +9,9 @@ class DuplicableTest < ActiveSupport::TestCase
   ALLOW_DUP << BigDecimal.new('4.56')
 
   def test_duplicable
+    rubinius_skip "* Method#dup is allowed at the moment on Rubinius\n" \
+                  "* https://github.com/rubinius/rubinius/issues/3089"
+
     RAISE_DUP.each do |v|
       assert !v.duplicable?
       assert_raises(TypeError, v.class.name) { v.dup }
diff --git a/activesupport/test/core_ext/object/json_gem_encoding_test.rb b/activesupport/test/core_ext/object/json_gem_encoding_test.rb
new file mode 100644
index 0000000000..02ab17fb64
--- /dev/null
+++ b/activesupport/test/core_ext/object/json_gem_encoding_test.rb
@@ -0,0 +1,66 @@
+require 'abstract_unit'
+require 'json'
+require 'json/encoding_test_cases'
+
+# These test cases were added to test that we do not interfere with json gem's
+# output when the AS encoder is loaded, primarily for problems reported in
+# #20775. They need to be executed in isolation to reproduce the scenario
+# correctly, because other test cases might have already loaded additional
+# dependencies.
+
+# The AS::JSON encoder requires the BigDecimal core_ext, which, unfortunately,
+# changes the BigDecimal#to_s output, and consequently the JSON gem output. So
+# we need to require this unfront to ensure we don't get a false failure, but
+# ideally we should just fix the BigDecimal core_ext to not change to_s without
+# arguments.
+require 'active_support/core_ext/big_decimal'
+
+class JsonGemEncodingTest < ActiveSupport::TestCase
+  include ActiveSupport::Testing::Isolation
+
+  JSONTest::EncodingTestCases.constants.each_with_index do |name|
+    JSONTest::EncodingTestCases.const_get(name).each_with_index do |(subject, _), i|
+      test("#{name[0..-6].underscore} #{i}") do
+        assert_same_with_or_without_active_support(subject)
+      end
+    end
+  end
+
+  class CustomToJson
+    def to_json(*)
+      '"custom"'
+    end
+  end
+
+  test "custom to_json" do
+    assert_same_with_or_without_active_support(CustomToJson.new)
+  end
+
+  private
+    def require_or_skip(file)
+      require(file) || skip("'#{file}' was already loaded")
+    end
+
+    def assert_same_with_or_without_active_support(subject)
+      begin
+        expected = JSON.generate(subject, quirks_mode: true)
+      rescue JSON::GeneratorError => e
+        exception = e
+      end
+
+      require_or_skip 'active_support/core_ext/object/json'
+
+      if exception
+        assert_raises_with_message JSON::GeneratorError, e.message do
+          JSON.generate(subject, quirks_mode: true)
+        end
+      else
+        assert_equal expected, JSON.generate(subject, quirks_mode: true)
+      end
+    end
+
+    def assert_raises_with_message(exception_class, message, &block)
+      err = assert_raises(exception_class) { block.call }
+      assert_match message, err.message
+    end
+end
diff --git a/activesupport/test/core_ext/object/try_test.rb b/activesupport/test/core_ext/object/try_test.rb
index 89438675c1..25bf0207b8 100644
--- a/activesupport/test/core_ext/object/try_test.rb
+++ b/activesupport/test/core_ext/object/try_test.rb
@@ -77,9 +77,9 @@ class ObjectTryTest < ActiveSupport::TestCase
     klass = Class.new do
       private
 
-      def private_method
-        'private method'
-      end
+        def private_method
+          'private method'
+        end
     end
 
     assert_raise(NoMethodError) { klass.new.try!(:private_method) }
@@ -89,11 +89,75 @@ class ObjectTryTest < ActiveSupport::TestCase
     klass = Class.new do
       private
 
-      def private_method
-        'private method'
-      end
+        def private_method
+          'private method'
+        end
     end
 
     assert_nil klass.new.try(:private_method)
   end
+
+  class Decorator < SimpleDelegator
+    def delegator_method
+      'delegator method'
+    end
+
+    def reverse
+      'overridden reverse'
+    end
+
+    private
+
+      def private_delegator_method
+        'private delegator method'
+      end
+  end
+
+  def test_try_with_method_on_delegator
+    assert_equal 'delegator method', Decorator.new(@string).try(:delegator_method)
+  end
+
+  def test_try_with_method_on_delegator_target
+    assert_equal 5, Decorator.new(@string).size
+  end
+
+  def test_try_with_overridden_method_on_delegator
+    assert_equal 'overridden reverse', Decorator.new(@string).reverse
+  end
+
+  def test_try_with_private_method_on_delegator
+    assert_nil Decorator.new(@string).try(:private_delegator_method)
+  end
+
+  def test_try_with_private_method_on_delegator_bang
+    assert_raise(NoMethodError) do
+      Decorator.new(@string).try!(:private_delegator_method)
+    end
+  end
+
+  def test_try_with_private_method_on_delegator_target
+    klass = Class.new do
+      private
+
+        def private_method
+          'private method'
+        end
+    end
+
+    assert_nil Decorator.new(klass.new).try(:private_method)
+  end
+
+  def test_try_with_private_method_on_delegator_target_bang
+    klass = Class.new do
+      private
+
+        def private_method
+          'private method'
+        end
+    end
+
+    assert_raise(NoMethodError) do
+      Decorator.new(klass.new).try!(:private_method)
+    end
+  end
 end
diff --git a/activesupport/test/core_ext/securerandom.rb b/activesupport/test/core_ext/secure_random_test.rb
index dfacb7fe9f..dfacb7fe9f 100644
--- a/activesupport/test/core_ext/securerandom.rb
+++ b/activesupport/test/core_ext/secure_random_test.rb
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index cdc695f036..9cc7bb1a77 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'date'
 require 'abstract_unit'
 require 'inflector_test_cases'
@@ -250,6 +249,15 @@ class StringInflectionsTest < ActiveSupport::TestCase
     assert_equal "Hello<br>Big<br>World!", "Hello<br>Big<br>World!".truncate_words(3, :omission => "[...]", :separator => '<br>')
   end
 
+  def test_truncate_words_with_complex_string
+    Timeout.timeout(10) do
+      complex_string = "aa aa aaa aa aaa aaa aaa aa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaaa aaaaa aaaaa aaaaaa aa aa aa aaa aa  aaa aa aa aa aa a aaa aaa \n a aaa <<s"
+      assert_equal complex_string.truncate_words(80), complex_string
+    end
+  rescue Timeout::Error
+    assert false
+  end
+
   def test_truncate_multibyte
     assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".force_encoding(Encoding::UTF_8),
       "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".force_encoding(Encoding::UTF_8).truncate(10)
@@ -427,117 +435,123 @@ class StringConversionsTest < ActiveSupport::TestCase
 
   def test_standard_time_string_to_time_when_current_time_is_standard_time
     with_env_tz "US/Eastern" do
-      Time.stubs(:now).returns(Time.local(2012, 1, 1))
-      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time
-      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 -0800".to_time
-      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 -0800".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 -0500".to_time
-      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 -0500".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 5, 0), "2012-01-01 10:00 UTC".to_time
-      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00 UTC".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 PST".to_time
-      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 PST".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 EST".to_time
-      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 EST".to_time(:utc)
+      Time.stub(:now, Time.local(2012, 1, 1)) do
+        assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time
+        assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 -0800".to_time
+        assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 -0800".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 -0500".to_time
+        assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 -0500".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 5, 0), "2012-01-01 10:00 UTC".to_time
+        assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00 UTC".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 PST".to_time
+        assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 PST".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 EST".to_time
+        assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 EST".to_time(:utc)
+      end
     end
   end
 
   def test_standard_time_string_to_time_when_current_time_is_daylight_savings
     with_env_tz "US/Eastern" do
-      Time.stubs(:now).returns(Time.local(2012, 7, 1))
-      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time
-      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 -0800".to_time
-      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 -0800".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 -0500".to_time
-      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 -0500".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 5, 0), "2012-01-01 10:00 UTC".to_time
-      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00 UTC".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 PST".to_time
-      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 PST".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 EST".to_time
-      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 EST".to_time(:utc)
+      Time.stub(:now, Time.local(2012, 7, 1)) do
+        assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time
+        assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 -0800".to_time
+        assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 -0800".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 -0500".to_time
+        assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 -0500".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 5, 0), "2012-01-01 10:00 UTC".to_time
+        assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00 UTC".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 PST".to_time
+        assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 PST".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 EST".to_time
+        assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 EST".to_time(:utc)
+      end
     end
   end
 
   def test_daylight_savings_string_to_time_when_current_time_is_standard_time
     with_env_tz "US/Eastern" do
-      Time.stubs(:now).returns(Time.local(2012, 1, 1))
-      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time
-      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 -0700".to_time
-      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 -0700".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 -0400".to_time
-      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 -0400".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 6, 0), "2012-07-01 10:00 UTC".to_time
-      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00 UTC".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 PDT".to_time
-      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 PDT".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 EDT".to_time
-      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 EDT".to_time(:utc)
+      Time.stub(:now, Time.local(2012, 1, 1)) do
+        assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time
+        assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 -0700".to_time
+        assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 -0700".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 -0400".to_time
+        assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 -0400".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 6, 0), "2012-07-01 10:00 UTC".to_time
+        assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00 UTC".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 PDT".to_time
+        assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 PDT".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 EDT".to_time
+        assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 EDT".to_time(:utc)
+      end
     end
   end
 
   def test_daylight_savings_string_to_time_when_current_time_is_daylight_savings
     with_env_tz "US/Eastern" do
-      Time.stubs(:now).returns(Time.local(2012, 7, 1))
-      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time
-      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 -0700".to_time
-      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 -0700".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 -0400".to_time
-      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 -0400".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 6, 0), "2012-07-01 10:00 UTC".to_time
-      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00 UTC".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 PDT".to_time
-      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 PDT".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 EDT".to_time
-      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 EDT".to_time(:utc)
+      Time.stub(:now, Time.local(2012, 7, 1)) do
+        assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time
+        assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 -0700".to_time
+        assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 -0700".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 -0400".to_time
+        assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 -0400".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 6, 0), "2012-07-01 10:00 UTC".to_time
+        assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00 UTC".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 PDT".to_time
+        assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 PDT".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 EDT".to_time
+        assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 EDT".to_time(:utc)
+      end
     end
   end
 
   def test_partial_string_to_time_when_current_time_is_standard_time
     with_env_tz "US/Eastern" do
-      Time.stubs(:now).returns(Time.local(2012, 1, 1))
-      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00".to_time
-      assert_equal Time.utc(2012, 1, 1, 10, 0),  "10:00".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 6, 0), "10:00 -0100".to_time
-      assert_equal Time.utc(2012, 1, 1, 11, 0), "10:00 -0100".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00 -0500".to_time
-      assert_equal Time.utc(2012, 1, 1, 15, 0), "10:00 -0500".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 5, 0), "10:00 UTC".to_time
-      assert_equal Time.utc(2012, 1, 1, 10, 0), "10:00 UTC".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 13, 0), "10:00 PST".to_time
-      assert_equal Time.utc(2012, 1, 1, 18, 0), "10:00 PST".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 12, 0), "10:00 PDT".to_time
-      assert_equal Time.utc(2012, 1, 1, 17, 0), "10:00 PDT".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00 EST".to_time
-      assert_equal Time.utc(2012, 1, 1, 15, 0), "10:00 EST".to_time(:utc)
-      assert_equal Time.local(2012, 1, 1, 9, 0), "10:00 EDT".to_time
-      assert_equal Time.utc(2012, 1, 1, 14, 0), "10:00 EDT".to_time(:utc)
+      Time.stub(:now, Time.local(2012, 1, 1)) do
+        assert_equal Time.local(2012, 1, 1, 10, 0), "10:00".to_time
+        assert_equal Time.utc(2012, 1, 1, 10, 0),  "10:00".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 6, 0), "10:00 -0100".to_time
+        assert_equal Time.utc(2012, 1, 1, 11, 0), "10:00 -0100".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 10, 0), "10:00 -0500".to_time
+        assert_equal Time.utc(2012, 1, 1, 15, 0), "10:00 -0500".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 5, 0), "10:00 UTC".to_time
+        assert_equal Time.utc(2012, 1, 1, 10, 0), "10:00 UTC".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 13, 0), "10:00 PST".to_time
+        assert_equal Time.utc(2012, 1, 1, 18, 0), "10:00 PST".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 12, 0), "10:00 PDT".to_time
+        assert_equal Time.utc(2012, 1, 1, 17, 0), "10:00 PDT".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 10, 0), "10:00 EST".to_time
+        assert_equal Time.utc(2012, 1, 1, 15, 0), "10:00 EST".to_time(:utc)
+        assert_equal Time.local(2012, 1, 1, 9, 0), "10:00 EDT".to_time
+        assert_equal Time.utc(2012, 1, 1, 14, 0), "10:00 EDT".to_time(:utc)
+      end
     end
   end
 
   def test_partial_string_to_time_when_current_time_is_daylight_savings
     with_env_tz "US/Eastern" do
-      Time.stubs(:now).returns(Time.local(2012, 7, 1))
-      assert_equal Time.local(2012, 7, 1, 10, 0), "10:00".to_time
-      assert_equal Time.utc(2012, 7, 1, 10, 0), "10:00".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 7, 0), "10:00 -0100".to_time
-      assert_equal Time.utc(2012, 7, 1, 11, 0), "10:00 -0100".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 11, 0), "10:00 -0500".to_time
-      assert_equal Time.utc(2012, 7, 1, 15, 0), "10:00 -0500".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 6, 0), "10:00 UTC".to_time
-      assert_equal Time.utc(2012, 7, 1, 10, 0), "10:00 UTC".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 14, 0), "10:00 PST".to_time
-      assert_equal Time.utc(2012, 7, 1, 18, 0), "10:00 PST".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 13, 0), "10:00 PDT".to_time
-      assert_equal Time.utc(2012, 7, 1, 17, 0), "10:00 PDT".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 11, 0), "10:00 EST".to_time
-      assert_equal Time.utc(2012, 7, 1, 15, 0), "10:00 EST".to_time(:utc)
-      assert_equal Time.local(2012, 7, 1, 10, 0), "10:00 EDT".to_time
-      assert_equal Time.utc(2012, 7, 1, 14, 0), "10:00 EDT".to_time(:utc)
+      Time.stub(:now, Time.local(2012, 7, 1)) do
+        assert_equal Time.local(2012, 7, 1, 10, 0), "10:00".to_time
+        assert_equal Time.utc(2012, 7, 1, 10, 0), "10:00".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 7, 0), "10:00 -0100".to_time
+        assert_equal Time.utc(2012, 7, 1, 11, 0), "10:00 -0100".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 11, 0), "10:00 -0500".to_time
+        assert_equal Time.utc(2012, 7, 1, 15, 0), "10:00 -0500".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 6, 0), "10:00 UTC".to_time
+        assert_equal Time.utc(2012, 7, 1, 10, 0), "10:00 UTC".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 14, 0), "10:00 PST".to_time
+        assert_equal Time.utc(2012, 7, 1, 18, 0), "10:00 PST".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 13, 0), "10:00 PDT".to_time
+        assert_equal Time.utc(2012, 7, 1, 17, 0), "10:00 PDT".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 11, 0), "10:00 EST".to_time
+        assert_equal Time.utc(2012, 7, 1, 15, 0), "10:00 EST".to_time(:utc)
+        assert_equal Time.local(2012, 7, 1, 10, 0), "10:00 EDT".to_time
+        assert_equal Time.utc(2012, 7, 1, 14, 0), "10:00 EDT".to_time(:utc)
+      end
     end
   end
 
@@ -768,8 +782,8 @@ class OutputSafetyTest < ActiveSupport::TestCase
   end
 
   test "ERB::Util.html_escape should correctly handle invalid UTF-8 strings" do
-    string = [192, 60].pack('CC')
-    expected = 192.chr + "&lt;"
+    string = "\251 <"
+    expected = "© &lt;"
     assert_equal expected, ERB::Util.html_escape(string)
   end
 
@@ -785,6 +799,12 @@ class OutputSafetyTest < ActiveSupport::TestCase
     assert_equal escaped_string, ERB::Util.html_escape_once(string)
     assert_equal escaped_string, ERB::Util.html_escape_once(escaped_string)
   end
+
+  test "ERB::Util.html_escape_once should correctly handle invalid UTF-8 strings" do
+    string = "\251 <"
+    expected = "© &lt;"
+    assert_equal expected, ERB::Util.html_escape_once(string)
+  end
 end
 
 class StringExcludeTest < ActiveSupport::TestCase
diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index d59775001b..2d0fb70a6b 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -149,6 +149,9 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
       assert_equal Time.local(2006,3,19,23,59,59,Rational(999999999, 1000)), Time.local(2006,3,19,10,10,10).end_of_day, 'ends DST'
       assert_equal Time.local(2006,10,1,23,59,59,Rational(999999999, 1000)), Time.local(2006,10,1,10,10,10).end_of_day, 'start DST'
     end
+    with_env_tz 'Asia/Yekaterinburg' do
+      assert_equal Time.local(2015, 2, 8, 23, 59, 59, Rational(999999999, 1000)), Time.new(2015, 2, 8, 8, 0, 0, '+05:00').end_of_day
+    end
   end
 
   def test_end_of_hour
@@ -389,6 +392,7 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
     assert_equal Time.local(2005,1,2,11,22,33, 8), Time.local(2005,1,2,11,22,33,44).change(:usec => 8)
     assert_equal Time.local(2005,1,2,11,22,33, 8), Time.local(2005,1,2,11,22,33,2).change(:nsec => 8000)
     assert_raise(ArgumentError) { Time.local(2005,1,2,11,22,33, 8).change(:usec => 1, :nsec => 1) }
+    assert_nothing_raised(ArgumentError) { Time.new(2015, 5, 9, 10, 00, 00, '+03:00').change(nsec: 999999999) }
   end
 
   def test_utc_change
@@ -530,6 +534,7 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
     assert_equal "17:44",                           time.to_s(:time)
     assert_equal "20050221174430",                  time.to_s(:number)
     assert_equal "20050221174430123456789",         time.to_s(:nsec)
+    assert_equal "20050221174430123456",            time.to_s(:usec)
     assert_equal "February 21, 2005 17:44",         time.to_s(:long)
     assert_equal "February 21st, 2005 17:44",       time.to_s(:long_ordinal)
     with_env_tz "UTC" do
@@ -601,13 +606,15 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
   end
 
   def test_days_in_month_feb_in_common_year_without_year_arg
-    Time.stubs(:now).returns(Time.utc(2007))
-    assert_equal 28, Time.days_in_month(2)
+    Time.stub(:now, Time.utc(2007)) do
+      assert_equal 28, Time.days_in_month(2)
+    end
   end
 
   def test_days_in_month_feb_in_leap_year_without_year_arg
-    Time.stubs(:now).returns(Time.utc(2008))
-    assert_equal 29, Time.days_in_month(2)
+    Time.stub(:now, Time.utc(2008)) do
+      assert_equal 29, Time.days_in_month(2)
+    end
   end
 
   def test_last_month_on_31st
@@ -619,68 +626,74 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
   end
 
   def test_today_with_time_local
-    Date.stubs(:current).returns(Date.new(2000, 1, 1))
-    assert_equal false, Time.local(1999,12,31,23,59,59).today?
-    assert_equal true,  Time.local(2000,1,1,0).today?
-    assert_equal true,  Time.local(2000,1,1,23,59,59).today?
-    assert_equal false, Time.local(2000,1,2,0).today?
+    Date.stub(:current, Date.new(2000, 1, 1)) do
+      assert_equal false, Time.local(1999,12,31,23,59,59).today?
+      assert_equal true,  Time.local(2000,1,1,0).today?
+      assert_equal true,  Time.local(2000,1,1,23,59,59).today?
+      assert_equal false, Time.local(2000,1,2,0).today?
+    end
   end
 
   def test_today_with_time_utc
-    Date.stubs(:current).returns(Date.new(2000, 1, 1))
-    assert_equal false, Time.utc(1999,12,31,23,59,59).today?
-    assert_equal true,  Time.utc(2000,1,1,0).today?
-    assert_equal true,  Time.utc(2000,1,1,23,59,59).today?
-    assert_equal false, Time.utc(2000,1,2,0).today?
+    Date.stub(:current, Date.new(2000, 1, 1)) do
+      assert_equal false, Time.utc(1999,12,31,23,59,59).today?
+      assert_equal true,  Time.utc(2000,1,1,0).today?
+      assert_equal true,  Time.utc(2000,1,1,23,59,59).today?
+      assert_equal false, Time.utc(2000,1,2,0).today?
+    end
   end
 
   def test_past_with_time_current_as_time_local
     with_env_tz 'US/Eastern' do
-      Time.stubs(:current).returns(Time.local(2005,2,10,15,30,45))
-      assert_equal true,  Time.local(2005,2,10,15,30,44).past?
-      assert_equal false,  Time.local(2005,2,10,15,30,45).past?
-      assert_equal false,  Time.local(2005,2,10,15,30,46).past?
-      assert_equal true,  Time.utc(2005,2,10,20,30,44).past?
-      assert_equal false,  Time.utc(2005,2,10,20,30,45).past?
-      assert_equal false,  Time.utc(2005,2,10,20,30,46).past?
+      Time.stub(:current, Time.local(2005,2,10,15,30,45)) do
+        assert_equal true,  Time.local(2005,2,10,15,30,44).past?
+        assert_equal false,  Time.local(2005,2,10,15,30,45).past?
+        assert_equal false,  Time.local(2005,2,10,15,30,46).past?
+        assert_equal true,  Time.utc(2005,2,10,20,30,44).past?
+        assert_equal false,  Time.utc(2005,2,10,20,30,45).past?
+        assert_equal false,  Time.utc(2005,2,10,20,30,46).past?
+      end
     end
   end
 
   def test_past_with_time_current_as_time_with_zone
     with_env_tz 'US/Eastern' do
       twz = Time.utc(2005,2,10,15,30,45).in_time_zone('Central Time (US & Canada)')
-      Time.stubs(:current).returns(twz)
-      assert_equal true,  Time.local(2005,2,10,10,30,44).past?
-      assert_equal false,  Time.local(2005,2,10,10,30,45).past?
-      assert_equal false,  Time.local(2005,2,10,10,30,46).past?
-      assert_equal true,  Time.utc(2005,2,10,15,30,44).past?
-      assert_equal false,  Time.utc(2005,2,10,15,30,45).past?
-      assert_equal false,  Time.utc(2005,2,10,15,30,46).past?
+      Time.stub(:current, twz) do
+        assert_equal true,  Time.local(2005,2,10,10,30,44).past?
+        assert_equal false,  Time.local(2005,2,10,10,30,45).past?
+        assert_equal false,  Time.local(2005,2,10,10,30,46).past?
+        assert_equal true,  Time.utc(2005,2,10,15,30,44).past?
+        assert_equal false,  Time.utc(2005,2,10,15,30,45).past?
+        assert_equal false,  Time.utc(2005,2,10,15,30,46).past?
+      end
     end
   end
 
   def test_future_with_time_current_as_time_local
     with_env_tz 'US/Eastern' do
-      Time.stubs(:current).returns(Time.local(2005,2,10,15,30,45))
-      assert_equal false,  Time.local(2005,2,10,15,30,44).future?
-      assert_equal false,  Time.local(2005,2,10,15,30,45).future?
-      assert_equal true,  Time.local(2005,2,10,15,30,46).future?
-      assert_equal false,  Time.utc(2005,2,10,20,30,44).future?
-      assert_equal false,  Time.utc(2005,2,10,20,30,45).future?
-      assert_equal true,  Time.utc(2005,2,10,20,30,46).future?
+      Time.stub(:current, Time.local(2005,2,10,15,30,45)) do
+        assert_equal false,  Time.local(2005,2,10,15,30,44).future?
+        assert_equal false,  Time.local(2005,2,10,15,30,45).future?
+        assert_equal true,  Time.local(2005,2,10,15,30,46).future?
+        assert_equal false,  Time.utc(2005,2,10,20,30,44).future?
+        assert_equal false,  Time.utc(2005,2,10,20,30,45).future?
+        assert_equal true,  Time.utc(2005,2,10,20,30,46).future?
+      end
     end
   end
 
   def test_future_with_time_current_as_time_with_zone
     with_env_tz 'US/Eastern' do
       twz = Time.utc(2005,2,10,15,30,45).in_time_zone('Central Time (US & Canada)')
-      Time.stubs(:current).returns(twz)
-      assert_equal false,  Time.local(2005,2,10,10,30,44).future?
-      assert_equal false,  Time.local(2005,2,10,10,30,45).future?
-      assert_equal true,  Time.local(2005,2,10,10,30,46).future?
-      assert_equal false,  Time.utc(2005,2,10,15,30,44).future?
-      assert_equal false,  Time.utc(2005,2,10,15,30,45).future?
-      assert_equal true,  Time.utc(2005,2,10,15,30,46).future?
+      Time.stub(:current, twz) do
+        assert_equal false,  Time.local(2005,2,10,10,30,44).future?
+        assert_equal false,  Time.local(2005,2,10,10,30,45).future?
+        assert_equal true,  Time.local(2005,2,10,10,30,46).future?
+        assert_equal false,  Time.utc(2005,2,10,15,30,44).future?
+        assert_equal false,  Time.utc(2005,2,10,15,30,45).future?
+        assert_equal true,  Time.utc(2005,2,10,15,30,46).future?
+      end
     end
   end
 
@@ -721,6 +734,13 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
     assert_equal(-1, Time.utc(2000) <=> ActiveSupport::TimeWithZone.new( Time.utc(2000, 1, 1, 0, 0, 1), ActiveSupport::TimeZone['UTC'] ))
   end
 
+  def test_compare_with_string
+    assert_equal   1, Time.utc(2000) <=> Time.utc(1999, 12, 31, 23, 59, 59, 999).to_s
+    assert_equal   0, Time.utc(2000) <=> Time.utc(2000, 1, 1, 0, 0, 0).to_s
+    assert_equal( -1, Time.utc(2000) <=> Time.utc(2000, 1, 1, 0, 0, 1, 0).to_s)
+    assert_equal nil, Time.utc(2000) <=> 'Invalid as Time'
+  end
+
   def test_at_with_datetime
     assert_equal Time.utc(2000, 1, 1, 0, 0, 0), Time.at(DateTime.civil(2000, 1, 1, 0, 0, 0))
 
diff --git a/activesupport/test/core_ext/time_with_zone_test.rb b/activesupport/test/core_ext/time_with_zone_test.rb
index 92c233d567..7acada011d 100644
--- a/activesupport/test/core_ext/time_with_zone_test.rb
+++ b/activesupport/test/core_ext/time_with_zone_test.rb
@@ -1,6 +1,8 @@
 require 'abstract_unit'
 require 'active_support/time'
 require 'time_zone_test_helpers'
+require 'active_support/core_ext/string/strip'
+require 'yaml'
 
 class TimeWithZoneTest < ActiveSupport::TestCase
   include TimeZoneTestHelpers
@@ -49,7 +51,22 @@ class TimeWithZoneTest < ActiveSupport::TestCase
 
   def test_utc?
     assert_equal false, @twz.utc?
+
     assert_equal true, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['UTC']).utc?
+    assert_equal true, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Etc/UTC']).utc?
+    assert_equal true, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Universal']).utc?
+    assert_equal true, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['UCT']).utc?
+    assert_equal true, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Etc/UCT']).utc?
+    assert_equal true, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Etc/Universal']).utc?
+
+    assert_equal false, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Africa/Abidjan']).utc?
+    assert_equal false, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Africa/Banjul']).utc?
+    assert_equal false, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Africa/Freetown']).utc?
+    assert_equal false, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['GMT']).utc?
+    assert_equal false, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['GMT0']).utc?
+    assert_equal false, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Greenwich']).utc?
+    assert_equal false, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Iceland']).utc?
+    assert_equal false, ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['Africa/Monrovia']).utc?
   end
 
   def test_formatted_offset
@@ -108,14 +125,14 @@ class TimeWithZoneTest < ActiveSupport::TestCase
     @twz += 0.1234560001 # advance the time by a fraction of a second
     assert_equal "1999-12-31T19:00:00.123-05:00", @twz.xmlschema(3)
     assert_equal "1999-12-31T19:00:00.123456-05:00", @twz.xmlschema(6)
-    assert_equal "1999-12-31T19:00:00.123456-05:00", @twz.xmlschema(12)
+    assert_equal "1999-12-31T19:00:00.123456000100-05:00", @twz.xmlschema(12)
   end
 
   def test_xmlschema_with_fractional_seconds_lower_than_hundred_thousand
     @twz += 0.001234 # advance the time by a fraction
     assert_equal "1999-12-31T19:00:00.001-05:00", @twz.xmlschema(3)
     assert_equal "1999-12-31T19:00:00.001234-05:00", @twz.xmlschema(6)
-    assert_equal "1999-12-31T19:00:00.001234-05:00", @twz.xmlschema(12)
+    assert_equal "1999-12-31T19:00:00.001234000000-05:00", @twz.xmlschema(12)
   end
 
   def test_xmlschema_with_nil_fractional_seconds
@@ -123,11 +140,53 @@ class TimeWithZoneTest < ActiveSupport::TestCase
   end
 
   def test_to_yaml
-    assert_match(/^--- 2000-01-01 00:00:00(\.0+)?\s*Z\n/, @twz.to_yaml)
+    yaml = <<-EOF.strip_heredoc
+      --- !ruby/object:ActiveSupport::TimeWithZone
+      utc: 2000-01-01 00:00:00.000000000 Z
+      zone: !ruby/object:ActiveSupport::TimeZone
+        name: America/New_York
+      time: 1999-12-31 19:00:00.000000000 Z
+    EOF
+
+    assert_equal(yaml, @twz.to_yaml)
   end
 
   def test_ruby_to_yaml
-    assert_match(/---\s*\n:twz: 2000-01-01 00:00:00(\.0+)?\s*Z\n/, {:twz => @twz}.to_yaml)
+    yaml = <<-EOF.strip_heredoc
+      ---
+      twz: !ruby/object:ActiveSupport::TimeWithZone
+        utc: 2000-01-01 00:00:00.000000000 Z
+        zone: !ruby/object:ActiveSupport::TimeZone
+          name: America/New_York
+        time: 1999-12-31 19:00:00.000000000 Z
+    EOF
+
+    assert_equal(yaml, { 'twz' => @twz }.to_yaml)
+  end
+
+  def test_yaml_load
+    yaml = <<-EOF.strip_heredoc
+      --- !ruby/object:ActiveSupport::TimeWithZone
+      utc: 2000-01-01 00:00:00.000000000 Z
+      zone: !ruby/object:ActiveSupport::TimeZone
+        name: America/New_York
+      time: 1999-12-31 19:00:00.000000000 Z
+    EOF
+
+    assert_equal(@twz, YAML.load(yaml))
+  end
+
+  def test_ruby_yaml_load
+    yaml = <<-EOF.strip_heredoc
+      ---
+      twz: !ruby/object:ActiveSupport::TimeWithZone
+        utc: 2000-01-01 00:00:00.000000000 Z
+        zone: !ruby/object:ActiveSupport::TimeZone
+          name: America/New_York
+        time: 1999-12-31 19:00:00.000000000 Z
+    EOF
+
+    assert_equal({ 'twz' => @twz }, YAML.load(yaml))
   end
 
   def test_httpdate
@@ -162,52 +221,61 @@ class TimeWithZoneTest < ActiveSupport::TestCase
   end
 
   def test_today
-    Date.stubs(:current).returns(Date.new(2000, 1, 1))
-    assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.utc(1999,12,31,23,59,59) ).today?
-    assert_equal true,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.utc(2000,1,1,0) ).today?
-    assert_equal true,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.utc(2000,1,1,23,59,59) ).today?
-    assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.utc(2000,1,2,0) ).today?
+    Date.stub(:current, Date.new(2000, 1, 1)) do
+      assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.utc(1999,12,31,23,59,59) ).today?
+      assert_equal true, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.utc(2000,1,1,0) ).today?
+      assert_equal true, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.utc(2000,1,1,23,59,59) ).today?
+      assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.utc(2000,1,2,0) ).today?
+    end
   end
 
   def test_past_with_time_current_as_time_local
     with_env_tz 'US/Eastern' do
-      Time.stubs(:current).returns(Time.local(2005,2,10,15,30,45))
-      assert_equal true,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,44)).past?
-      assert_equal false,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45)).past?
-      assert_equal false,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,46)).past?
+      Time.stub(:current, Time.local(2005,2,10,15,30,45)) do
+        assert_equal true, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,44)).past?
+        assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45)).past?
+        assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,46)).past?
+      end
     end
   end
 
   def test_past_with_time_current_as_time_with_zone
     twz = ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45) )
-    Time.stubs(:current).returns(twz)
-    assert_equal true,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,44)).past?
-    assert_equal false,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45)).past?
-    assert_equal false,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,46)).past?
+    Time.stub(:current, twz) do
+      assert_equal true, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,44)).past?
+      assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45)).past?
+      assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,46)).past?
+    end
   end
 
   def test_future_with_time_current_as_time_local
     with_env_tz 'US/Eastern' do
-      Time.stubs(:current).returns(Time.local(2005,2,10,15,30,45))
-      assert_equal false,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,44)).future?
-      assert_equal false,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45)).future?
-      assert_equal true,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,46)).future?
+      Time.stub(:current, Time.local(2005,2,10,15,30,45)) do
+        assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,44)).future?
+        assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45)).future?
+        assert_equal true, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,46)).future?
+      end
     end
   end
 
   def test_future_with_time_current_as_time_with_zone
     twz = ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45) )
-    Time.stubs(:current).returns(twz)
-    assert_equal false,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,44)).future?
-    assert_equal false,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45)).future?
-    assert_equal true,  ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,46)).future?
+    Time.stub(:current, twz) do
+      assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,44)).future?
+      assert_equal false, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,45)).future?
+      assert_equal true, ActiveSupport::TimeWithZone.new( nil, @time_zone, Time.local(2005,2,10,15,30,46)).future?
+    end
   end
 
   def test_eql?
+    assert_equal true, @twz.eql?(@twz.dup)
     assert_equal true, @twz.eql?(Time.utc(2000))
     assert_equal true, @twz.eql?( ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone["Hawaii"]) )
     assert_equal false, @twz.eql?( Time.utc(2000, 1, 1, 0, 0, 1) )
     assert_equal false, @twz.eql?( DateTime.civil(1999, 12, 31, 23, 59, 59) )
+
+    other_twz = ActiveSupport::TimeWithZone.new(DateTime.now.utc, @time_zone)
+    assert_equal true, other_twz.eql?(other_twz.dup)
   end
 
   def test_hash
@@ -434,22 +502,24 @@ class TimeWithZoneTest < ActiveSupport::TestCase
   end
 
   def test_method_missing_with_non_time_return_value
-    @twz.time.expects(:foo).returns('bar')
+    time = @twz.time
+    def time.foo; 'bar'; end
     assert_equal 'bar', @twz.foo
   end
 
   def test_date_part_value_methods
     twz = ActiveSupport::TimeWithZone.new(Time.utc(1999,12,31,19,18,17,500), @time_zone)
-    twz.expects(:method_missing).never
-    assert_equal 1999, twz.year
-    assert_equal 12, twz.month
-    assert_equal 31, twz.day
-    assert_equal 14, twz.hour
-    assert_equal 18, twz.min
-    assert_equal 17, twz.sec
-    assert_equal 500, twz.usec
-    assert_equal 5, twz.wday
-    assert_equal 365, twz.yday
+    assert_not_called(twz, :method_missing) do
+      assert_equal 1999, twz.year
+      assert_equal 12, twz.month
+      assert_equal 31, twz.day
+      assert_equal 14, twz.hour
+      assert_equal 18, twz.min
+      assert_equal 17, twz.sec
+      assert_equal 500, twz.usec
+      assert_equal 5, twz.wday
+      assert_equal 365, twz.yday
+    end
   end
 
   def test_usec_returns_0_when_datetime_is_wrapped
@@ -990,19 +1060,21 @@ class TimeWithZoneMethodsForTimeAndDateTimeTest < ActiveSupport::TestCase
 
   def test_current_returns_time_now_when_zone_not_set
     with_env_tz 'US/Eastern' do
-      Time.stubs(:now).returns Time.local(2000)
-      assert_equal false, Time.current.is_a?(ActiveSupport::TimeWithZone)
-      assert_equal Time.local(2000), Time.current
+      Time.stub(:now, Time.local(2000)) do
+        assert_equal false, Time.current.is_a?(ActiveSupport::TimeWithZone)
+        assert_equal Time.local(2000), Time.current
+      end
     end
   end
 
   def test_current_returns_time_zone_now_when_zone_set
     Time.zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
     with_env_tz 'US/Eastern' do
-      Time.stubs(:now).returns Time.local(2000)
-      assert_equal true, Time.current.is_a?(ActiveSupport::TimeWithZone)
-      assert_equal 'Eastern Time (US & Canada)', Time.current.time_zone.name
-      assert_equal Time.utc(2000), Time.current.time
+      Time.stub(:now, Time.local(2000)) do
+        assert_equal true, Time.current.is_a?(ActiveSupport::TimeWithZone)
+        assert_equal 'Eastern Time (US & Canada)', Time.current.time_zone.name
+        assert_equal Time.utc(2000), Time.current.time
+      end
     end
   end
 
diff --git a/activesupport/test/core_ext/uri_ext_test.rb b/activesupport/test/core_ext/uri_ext_test.rb
index 43a5997ddd..1694fe7e72 100644
--- a/activesupport/test/core_ext/uri_ext_test.rb
+++ b/activesupport/test/core_ext/uri_ext_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'uri'
 require 'active_support/core_ext/uri'
diff --git a/activesupport/test/dependencies_test.rb b/activesupport/test/dependencies_test.rb
index 702e26859a..757e600646 100644
--- a/activesupport/test/dependencies_test.rb
+++ b/activesupport/test/dependencies_test.rb
@@ -160,7 +160,7 @@ class DependenciesTest < ActiveSupport::TestCase
   def test_ensures_the_expected_constant_is_defined
     with_autoloading_fixtures do
       e = assert_raise(LoadError) { Typo }
-      assert_match %r{Unable to autoload constant Typo, expected .*activesupport/test/autoloading_fixtures/typo.rb to define it}, e.message
+      assert_match %r{Unable to autoload constant Typo, expected .*/test/autoloading_fixtures/typo.rb to define it}, e.message
     end
   end
 
@@ -178,7 +178,7 @@ class DependenciesTest < ActiveSupport::TestCase
       assert_equal 1, TypO
 
       e = assert_raise(LoadError) { Typo }
-      assert_match %r{Unable to autoload constant Typo, expected .*activesupport/test/autoloading_fixtures/typo.rb to define it}, e.message
+      assert_match %r{Unable to autoload constant Typo, expected .*/test/autoloading_fixtures/typo.rb to define it}, e.message
     end
   end
 
@@ -187,7 +187,7 @@ class DependenciesTest < ActiveSupport::TestCase
       assert_kind_of Module, A
       assert_kind_of Class, A::B
       assert_kind_of Class, A::C::D
-      assert_kind_of Class, A::C::E::F
+      assert_kind_of Class, A::C::EM::F
     end
   end
 
@@ -552,24 +552,24 @@ class DependenciesTest < ActiveSupport::TestCase
   def test_const_missing_in_anonymous_modules_loads_top_level_constants
     with_autoloading_fixtures do
       # class_eval STRING pushes the class to the nesting of the eval'ed code.
-      klass = Class.new.class_eval "E"
-      assert_equal E, klass
+      klass = Class.new.class_eval "EM"
+      assert_equal EM, klass
     end
   ensure
-    remove_constants(:E)
+    remove_constants(:EM)
   end
 
   def test_const_missing_in_anonymous_modules_raises_if_the_constant_belongs_to_Object
     with_autoloading_fixtures do
-      require_dependency 'e'
+      require_dependency 'em'
 
       mod = Module.new
-      e = assert_raise(NameError) { mod::E }
-      assert_equal 'E cannot be autoloaded from an anonymous class or module', e.message
-      assert_equal :E, e.name
+      e = assert_raise(NameError) { mod::EM }
+      assert_equal 'EM cannot be autoloaded from an anonymous class or module', e.message
+      assert_equal :EM, e.name
     end
   ensure
-    remove_constants(:E)
+    remove_constants(:EM)
   end
 
   def test_removal_from_tree_should_be_detected
@@ -664,19 +664,19 @@ class DependenciesTest < ActiveSupport::TestCase
 
   def test_preexisting_constants_are_not_marked_as_autoloaded
     with_autoloading_fixtures do
-      require_dependency 'e'
-      assert ActiveSupport::Dependencies.autoloaded?(:E)
+      require_dependency 'em'
+      assert ActiveSupport::Dependencies.autoloaded?(:EM)
       ActiveSupport::Dependencies.clear
     end
 
-    Object.const_set :E, Class.new
+    Object.const_set :EM, Class.new
     with_autoloading_fixtures do
-      require_dependency 'e'
-      assert ! ActiveSupport::Dependencies.autoloaded?(:E), "E shouldn't be marked autoloaded!"
+      require_dependency 'em'
+      assert ! ActiveSupport::Dependencies.autoloaded?(:EM), "EM shouldn't be marked autoloaded!"
       ActiveSupport::Dependencies.clear
     end
   ensure
-    remove_constants(:E)
+    remove_constants(:EM)
   end
 
   def test_constants_in_capitalized_nesting_marked_as_autoloaded
@@ -721,12 +721,13 @@ class DependenciesTest < ActiveSupport::TestCase
   end
 
   def test_unloadable_constants_should_receive_callback
-    Object.const_set :C, Class.new
+    Object.const_set :C, Class.new { def self.before_remove_const; end }
     C.unloadable
-    C.expects(:before_remove_const).once
-    assert C.respond_to?(:before_remove_const)
-    ActiveSupport::Dependencies.clear
-    assert !defined?(C)
+    assert_called(C, :before_remove_const, times: 1) do
+      assert C.respond_to?(:before_remove_const)
+      ActiveSupport::Dependencies.clear
+      assert !defined?(C)
+    end
   ensure
     remove_constants(:C)
   end
diff --git a/activesupport/test/deprecation/method_wrappers_test.rb b/activesupport/test/deprecation/method_wrappers_test.rb
new file mode 100644
index 0000000000..9a4ca2b217
--- /dev/null
+++ b/activesupport/test/deprecation/method_wrappers_test.rb
@@ -0,0 +1,34 @@
+require 'abstract_unit'
+require 'active_support/deprecation'
+
+class MethodWrappersTest < ActiveSupport::TestCase
+  def setup
+    @klass = Class.new do
+      def new_method; "abc" end
+      alias_method :old_method, :new_method
+    end
+  end
+
+  def test_deprecate_methods_warning_default
+    warning = /old_method is deprecated and will be removed from Rails \d.\d \(use new_method instead\)/
+    ActiveSupport::Deprecation.deprecate_methods(@klass, :old_method => :new_method)
+
+    assert_deprecated(warning) { assert_equal "abc", @klass.new.old_method }
+  end
+
+  def test_deprecate_methods_warning_with_optional_deprecator
+    warning = /old_method is deprecated and will be removed from MyGem next-release \(use new_method instead\)/
+    deprecator = ActiveSupport::Deprecation.new("next-release", "MyGem")
+    ActiveSupport::Deprecation.deprecate_methods(@klass, :old_method => :new_method, :deprecator => deprecator)
+
+    assert_deprecated(warning, deprecator) { assert_equal "abc", @klass.new.old_method }
+  end
+
+  def test_deprecate_methods_warning_when_deprecated_with_custom_deprecator
+    warning = /old_method is deprecated and will be removed from MyGem next-release \(use new_method instead\)/
+    deprecator = ActiveSupport::Deprecation.new("next-release", "MyGem")
+    deprecator.deprecate_methods(@klass, :old_method => :new_method)
+
+    assert_deprecated(warning, deprecator) { assert_equal "abc", @klass.new.old_method }
+  end
+end
diff --git a/activesupport/test/deprecation_test.rb b/activesupport/test/deprecation_test.rb
index 7aff56cbad..cd02ad3f3f 100644
--- a/activesupport/test/deprecation_test.rb
+++ b/activesupport/test/deprecation_test.rb
@@ -1,4 +1,5 @@
 require 'abstract_unit'
+require 'active_support/testing/stream'
 
 class Deprecatee
   def initialize
@@ -36,6 +37,8 @@ end
 
 
 class DeprecationTest < ActiveSupport::TestCase
+  include ActiveSupport::Testing::Stream
+
   def setup
     # Track the last warning.
     @old_behavior = ActiveSupport::Deprecation.behavior
@@ -160,6 +163,14 @@ class DeprecationTest < ActiveSupport::TestCase
     assert_not_deprecated { assert_equal Deprecatee::B::C.class, Deprecatee::A.class }
   end
 
+  def test_assert_deprecated_raises_when_method_not_deprecated
+    assert_raises(Minitest::Assertion) { assert_deprecated { @dtc.not } }
+  end
+
+  def test_assert_not_deprecated
+    assert_raises(Minitest::Assertion) { assert_not_deprecated { @dtc.partially } }
+  end
+
   def test_assert_deprecation_without_match
     assert_deprecated do
       @dtc.partially
@@ -253,17 +264,17 @@ class DeprecationTest < ActiveSupport::TestCase
   end
 
   def test_deprecate_with_custom_deprecator
-    custom_deprecator = mock('Deprecator') do
-      expects(:deprecation_warning)
-    end
+    custom_deprecator = Struct.new(:deprecation_warning).new
 
-    klass = Class.new do
-      def method
+    assert_called_with(custom_deprecator, :deprecation_warning, [:method, nil]) do
+      klass = Class.new do
+        def method
+        end
+        deprecate :method, deprecator: custom_deprecator
       end
-      deprecate :method, deprecator: custom_deprecator
-    end
 
-    klass.new.method
+      klass.new.method
+    end
   end
 
   def test_deprecated_constant_with_deprecator_given
@@ -356,20 +367,4 @@ class DeprecationTest < ActiveSupport::TestCase
       deprecator
     end
 
-    def capture(stream)
-      stream = stream.to_s
-      captured_stream = Tempfile.new(stream)
-      stream_io = eval("$#{stream}")
-      origin_stream = stream_io.dup
-      stream_io.reopen(captured_stream)
-
-      yield
-
-      stream_io.rewind
-      return captured_stream.read
-    ensure
-      captured_stream.close
-      captured_stream.unlink
-      stream_io.reopen(origin_stream)
-    end
 end
diff --git a/activesupport/test/file_fixtures/sample.txt b/activesupport/test/file_fixtures/sample.txt
new file mode 100644
index 0000000000..0fa80e7383
--- /dev/null
+++ b/activesupport/test/file_fixtures/sample.txt
@@ -0,0 +1 @@
+sample file fixture
diff --git a/activesupport/test/hash_with_indifferent_access_test.rb b/activesupport/test/hash_with_indifferent_access_test.rb
deleted file mode 100644
index 843994147b..0000000000
--- a/activesupport/test/hash_with_indifferent_access_test.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require 'abstract_unit'
-require 'active_support/hash_with_indifferent_access'
-
-class HashWithIndifferentAccessTest < ActiveSupport::TestCase
-  def test_reverse_merge
-    hash = HashWithIndifferentAccess.new key: :old_value
-    hash.reverse_merge! key: :new_value
-    assert_equal :old_value, hash[:key]
-  end
-end
\ No newline at end of file
diff --git a/activesupport/test/inflector_test.rb b/activesupport/test/inflector_test.rb
index be68bb2e2e..a0764f6d6b 100644
--- a/activesupport/test/inflector_test.rb
+++ b/activesupport/test/inflector_test.rb
@@ -8,6 +8,20 @@ class InflectorTest < ActiveSupport::TestCase
   include InflectorTestCases
   include ConstantizeTestCases
 
+  def setup
+    # Dups the singleton before each test, restoring the original inflections later.
+    #
+    # This helper is implemented by setting @__instance__ because in some tests
+    # there are module functions that access ActiveSupport::Inflector.inflections,
+    # so we need to replace the singleton itself.
+    @original_inflections = ActiveSupport::Inflector::Inflections.instance_variable_get(:@__instance__)[:en]
+    ActiveSupport::Inflector::Inflections.instance_variable_set(:@__instance__, en: @original_inflections.dup)
+  end
+
+  def teardown
+    ActiveSupport::Inflector::Inflections.instance_variable_set(:@__instance__, en: @original_inflections)
+  end
+
   def test_pluralize_plurals
     assert_equal "plurals", ActiveSupport::Inflector.pluralize("plurals")
     assert_equal "Plurals", ActiveSupport::Inflector.pluralize("Plurals")
@@ -26,20 +40,18 @@ class InflectorTest < ActiveSupport::TestCase
   end
 
   def test_uncountable_word_is_not_greedy
-    with_dup do
-      uncountable_word = "ors"
-      countable_word = "sponsor"
+    uncountable_word = "ors"
+    countable_word = "sponsor"
 
-      ActiveSupport::Inflector.inflections.uncountable << uncountable_word
+    ActiveSupport::Inflector.inflections.uncountable << uncountable_word
 
-      assert_equal uncountable_word, ActiveSupport::Inflector.singularize(uncountable_word)
-      assert_equal uncountable_word, ActiveSupport::Inflector.pluralize(uncountable_word)
-      assert_equal ActiveSupport::Inflector.pluralize(uncountable_word), ActiveSupport::Inflector.singularize(uncountable_word)
+    assert_equal uncountable_word, ActiveSupport::Inflector.singularize(uncountable_word)
+    assert_equal uncountable_word, ActiveSupport::Inflector.pluralize(uncountable_word)
+    assert_equal ActiveSupport::Inflector.pluralize(uncountable_word), ActiveSupport::Inflector.singularize(uncountable_word)
 
-      assert_equal "sponsor", ActiveSupport::Inflector.singularize(countable_word)
-      assert_equal "sponsors", ActiveSupport::Inflector.pluralize(countable_word)
-      assert_equal "sponsor", ActiveSupport::Inflector.singularize(ActiveSupport::Inflector.pluralize(countable_word))
-    end
+    assert_equal "sponsor", ActiveSupport::Inflector.singularize(countable_word)
+    assert_equal "sponsors", ActiveSupport::Inflector.pluralize(countable_word)
+    assert_equal "sponsor", ActiveSupport::Inflector.singularize(ActiveSupport::Inflector.pluralize(countable_word))
   end
 
   SingularToPlural.each do |singular, plural|
@@ -70,11 +82,9 @@ class InflectorTest < ActiveSupport::TestCase
 
 
   def test_overwrite_previous_inflectors
-    with_dup do
-      assert_equal("series", ActiveSupport::Inflector.singularize("series"))
-      ActiveSupport::Inflector.inflections.singular "series", "serie"
-      assert_equal("serie", ActiveSupport::Inflector.singularize("series"))
-    end
+    assert_equal("series", ActiveSupport::Inflector.singularize("series"))
+    ActiveSupport::Inflector.inflections.singular "series", "serie"
+    assert_equal("serie", ActiveSupport::Inflector.singularize("series"))
   end
 
   MixtureToTitleCase.each_with_index do |(before, titleized), index|
@@ -367,10 +377,8 @@ class InflectorTest < ActiveSupport::TestCase
   %w{plurals singulars uncountables humans}.each do |inflection_type|
     class_eval <<-RUBY, __FILE__, __LINE__ + 1
       def test_clear_#{inflection_type}
-        with_dup do
-          ActiveSupport::Inflector.inflections.clear :#{inflection_type}
-          assert ActiveSupport::Inflector.inflections.#{inflection_type}.empty?, \"#{inflection_type} inflections should be empty after clear :#{inflection_type}\"
-        end
+        ActiveSupport::Inflector.inflections.clear :#{inflection_type}
+        assert ActiveSupport::Inflector.inflections.#{inflection_type}.empty?, \"#{inflection_type} inflections should be empty after clear :#{inflection_type}\"
       end
     RUBY
   end
@@ -405,73 +413,63 @@ class InflectorTest < ActiveSupport::TestCase
   end
 
   def test_clear_all
-    with_dup do
-      ActiveSupport::Inflector.inflections do |inflect|
-        # ensure any data is present
-        inflect.plural(/(quiz)$/i, '\1zes')
-        inflect.singular(/(database)s$/i, '\1')
-        inflect.uncountable('series')
-        inflect.human("col_rpted_bugs", "Reported bugs")
-
-        inflect.clear :all
-
-        assert inflect.plurals.empty?
-        assert inflect.singulars.empty?
-        assert inflect.uncountables.empty?
-        assert inflect.humans.empty?
-      end
+    ActiveSupport::Inflector.inflections do |inflect|
+      # ensure any data is present
+      inflect.plural(/(quiz)$/i, '\1zes')
+      inflect.singular(/(database)s$/i, '\1')
+      inflect.uncountable('series')
+      inflect.human("col_rpted_bugs", "Reported bugs")
+
+      inflect.clear :all
+
+      assert inflect.plurals.empty?
+      assert inflect.singulars.empty?
+      assert inflect.uncountables.empty?
+      assert inflect.humans.empty?
     end
   end
 
   def test_clear_with_default
-    with_dup do
-      ActiveSupport::Inflector.inflections do |inflect|
-        # ensure any data is present
-        inflect.plural(/(quiz)$/i, '\1zes')
-        inflect.singular(/(database)s$/i, '\1')
-        inflect.uncountable('series')
-        inflect.human("col_rpted_bugs", "Reported bugs")
-
-        inflect.clear
-
-        assert inflect.plurals.empty?
-        assert inflect.singulars.empty?
-        assert inflect.uncountables.empty?
-        assert inflect.humans.empty?
-      end
+    ActiveSupport::Inflector.inflections do |inflect|
+      # ensure any data is present
+      inflect.plural(/(quiz)$/i, '\1zes')
+      inflect.singular(/(database)s$/i, '\1')
+      inflect.uncountable('series')
+      inflect.human("col_rpted_bugs", "Reported bugs")
+
+      inflect.clear
+
+      assert inflect.plurals.empty?
+      assert inflect.singulars.empty?
+      assert inflect.uncountables.empty?
+      assert inflect.humans.empty?
     end
   end
 
   Irregularities.each do |singular, plural|
     define_method("test_irregularity_between_#{singular}_and_#{plural}") do
-      with_dup do
-        ActiveSupport::Inflector.inflections do |inflect|
-          inflect.irregular(singular, plural)
-          assert_equal singular, ActiveSupport::Inflector.singularize(plural)
-          assert_equal plural, ActiveSupport::Inflector.pluralize(singular)
-        end
+      ActiveSupport::Inflector.inflections do |inflect|
+        inflect.irregular(singular, plural)
+        assert_equal singular, ActiveSupport::Inflector.singularize(plural)
+        assert_equal plural, ActiveSupport::Inflector.pluralize(singular)
       end
     end
   end
 
   Irregularities.each do |singular, plural|
     define_method("test_pluralize_of_irregularity_#{plural}_should_be_the_same") do
-      with_dup do
-        ActiveSupport::Inflector.inflections do |inflect|
-          inflect.irregular(singular, plural)
-          assert_equal plural, ActiveSupport::Inflector.pluralize(plural)
-        end
+      ActiveSupport::Inflector.inflections do |inflect|
+        inflect.irregular(singular, plural)
+        assert_equal plural, ActiveSupport::Inflector.pluralize(plural)
       end
     end
   end
 
   Irregularities.each do |singular, plural|
     define_method("test_singularize_of_irregularity_#{singular}_should_be_the_same") do
-      with_dup do
-        ActiveSupport::Inflector.inflections do |inflect|
-          inflect.irregular(singular, plural)
-          assert_equal singular, ActiveSupport::Inflector.singularize(singular)
-        end
+      ActiveSupport::Inflector.inflections do |inflect|
+        inflect.irregular(singular, plural)
+        assert_equal singular, ActiveSupport::Inflector.singularize(singular)
       end
     end
   end
@@ -503,12 +501,10 @@ class InflectorTest < ActiveSupport::TestCase
 
   %w(plurals singulars uncountables humans acronyms).each do |scope|
     define_method("test_clear_inflections_with_#{scope}") do
-      with_dup do
-        # clear the inflections
-        ActiveSupport::Inflector.inflections do |inflect|
-          inflect.clear(scope)
-          assert_equal [], inflect.send(scope)
-        end
+      # clear the inflections
+      ActiveSupport::Inflector.inflections do |inflect|
+        inflect.clear(scope)
+        assert_equal [], inflect.send(scope)
       end
     end
   end
@@ -520,18 +516,4 @@ class InflectorTest < ActiveSupport::TestCase
 
     assert_equal "HTTP", ActiveSupport::Inflector.pluralize("HTTP")
   end
-
-  # Dups the singleton and yields, restoring the original inflections later.
-  # Use this in tests what modify the state of the singleton.
-  #
-  # This helper is implemented by setting @__instance__ because in some tests
-  # there are module functions that access ActiveSupport::Inflector.inflections,
-  # so we need to replace the singleton itself.
-  def with_dup
-    original = ActiveSupport::Inflector::Inflections.instance_variable_get(:@__instance__)[:en]
-    ActiveSupport::Inflector::Inflections.instance_variable_set(:@__instance__, en: original.dup)
-    yield
-  ensure
-    ActiveSupport::Inflector::Inflections.instance_variable_set(:@__instance__, en: original)
-  end
 end
diff --git a/activesupport/test/inflector_test_cases.rb b/activesupport/test/inflector_test_cases.rb
index 3770f00fe3..e6898658b5 100644
--- a/activesupport/test/inflector_test_cases.rb
+++ b/activesupport/test/inflector_test_cases.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 module InflectorTestCases
   SingularToPlural = {
     "search"      => "searches",
diff --git a/activesupport/test/json/decoding_test.rb b/activesupport/test/json/decoding_test.rb
index 80bf255080..f2fc456f4b 100644
--- a/activesupport/test/json/decoding_test.rb
+++ b/activesupport/test/json/decoding_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'active_support/json'
 require 'active_support/time'
diff --git a/activesupport/test/json/encoding_test.rb b/activesupport/test/json/encoding_test.rb
index 5c5045da1e..9f4b62fd8b 100644
--- a/activesupport/test/json/encoding_test.rb
+++ b/activesupport/test/json/encoding_test.rb
@@ -1,126 +1,27 @@
-# encoding: utf-8
 require 'securerandom'
 require 'abstract_unit'
 require 'active_support/core_ext/string/inflections'
 require 'active_support/json'
 require 'active_support/time'
 require 'time_zone_test_helpers'
+require 'json/encoding_test_cases'
 
 class TestJSONEncoding < ActiveSupport::TestCase
   include TimeZoneTestHelpers
 
-  class Foo
-    def initialize(a, b)
-      @a, @b = a, b
-    end
-  end
-
-  class Hashlike
-    def to_hash
-      { :foo => "hello", :bar => "world" }
-    end
-  end
-
-  class Custom
-    def initialize(serialized)
-      @serialized = serialized
-    end
-
-    def as_json(options = nil)
-      @serialized
-    end
-  end
-
-  class CustomWithOptions
-    attr_accessor :foo, :bar
-
-    def as_json(options={})
-      options[:only] = %w(foo bar)
-      super(options)
-    end
-  end
-
-  class OptionsTest
-    def as_json(options = :default)
-      options
-    end
-  end
-
-  class HashWithAsJson < Hash
-    attr_accessor :as_json_called
-
-    def initialize(*)
-      super
-    end
-
-    def as_json(options={})
-      @as_json_called = true
-      super
-    end
-  end
-
-  TrueTests     = [[ true,  %(true)  ]]
-  FalseTests    = [[ false, %(false) ]]
-  NilTests      = [[ nil,   %(null)  ]]
-  NumericTests  = [[ 1,     %(1)     ],
-                   [ 2.5,   %(2.5)   ],
-                   [ 0.0/0.0,   %(null) ],
-                   [ 1.0/0.0,   %(null) ],
-                   [ -1.0/0.0,  %(null) ],
-                   [ BigDecimal('0.0')/BigDecimal('0.0'),  %(null) ],
-                   [ BigDecimal('2.5'), %("#{BigDecimal('2.5')}") ]]
-
-  StringTests   = [[ 'this is the <string>',     %("this is the \\u003cstring\\u003e")],
-                   [ 'a "string" with quotes & an ampersand', %("a \\"string\\" with quotes \\u0026 an ampersand") ],
-                   [ 'http://test.host/posts/1', %("http://test.host/posts/1")],
-                   [ "Control characters: \x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\u2028\u2029",
-                     %("Control characters: \\u0000\\u0001\\u0002\\u0003\\u0004\\u0005\\u0006\\u0007\\b\\t\\n\\u000b\\f\\r\\u000e\\u000f\\u0010\\u0011\\u0012\\u0013\\u0014\\u0015\\u0016\\u0017\\u0018\\u0019\\u001a\\u001b\\u001c\\u001d\\u001e\\u001f\\u2028\\u2029") ]]
-
-  ArrayTests    = [[ ['a', 'b', 'c'],          %([\"a\",\"b\",\"c\"])          ],
-                   [ [1, 'a', :b, nil, false], %([1,\"a\",\"b\",null,false]) ]]
-
-  RangeTests    = [[ 1..2,     %("1..2")],
-                   [ 1...2,    %("1...2")],
-                   [ 1.5..2.5, %("1.5..2.5")]]
-
-  SymbolTests   = [[ :a,     %("a")    ],
-                   [ :this,  %("this") ],
-                   [ :"a b", %("a b")  ]]
-
-  ObjectTests   = [[ Foo.new(1, 2), %({\"a\":1,\"b\":2}) ]]
-  HashlikeTests = [[ Hashlike.new, %({\"bar\":\"world\",\"foo\":\"hello\"}) ]]
-  CustomTests   = [[ Custom.new("custom"), '"custom"' ],
-                   [ Custom.new(nil), 'null' ],
-                   [ Custom.new(:a), '"a"' ],
-                   [ Custom.new([ :foo, "bar" ]), '["foo","bar"]' ],
-                   [ Custom.new({ :foo => "hello", :bar => "world" }), '{"bar":"world","foo":"hello"}' ],
-                   [ Custom.new(Hashlike.new), '{"bar":"world","foo":"hello"}' ],
-                   [ Custom.new(Custom.new(Custom.new(:a))), '"a"' ]]
-
-  RegexpTests   = [[ /^a/, '"(?-mix:^a)"' ], [/^\w{1,2}[a-z]+/ix, '"(?ix-m:^\\\\w{1,2}[a-z]+)"']]
-
-  DateTests     = [[ Date.new(2005,2,1), %("2005/02/01") ]]
-  TimeTests     = [[ Time.utc(2005,2,1,15,15,10), %("2005/02/01 15:15:10 +0000") ]]
-  DateTimeTests = [[ DateTime.civil(2005,2,1,15,15,10), %("2005/02/01 15:15:10 +0000") ]]
-
-  StandardDateTests     = [[ Date.new(2005,2,1), %("2005-02-01") ]]
-  StandardTimeTests     = [[ Time.utc(2005,2,1,15,15,10), %("2005-02-01T15:15:10.000Z") ]]
-  StandardDateTimeTests = [[ DateTime.civil(2005,2,1,15,15,10), %("2005-02-01T15:15:10.000+00:00") ]]
-  StandardStringTests   = [[ 'this is the <string>', %("this is the <string>")]]
-
   def sorted_json(json)
     return json unless json =~ /^\{.*\}$/
     '{' + json[1..-2].split(',').sort.join(',') + '}'
   end
 
-  constants.grep(/Tests$/).each do |class_tests|
+  JSONTest::EncodingTestCases.constants.each do |class_tests|
     define_method("test_#{class_tests[0..-6].underscore}") do
       begin
         prev = ActiveSupport.use_standard_json_time_format
 
         ActiveSupport.escape_html_entities_in_json  = class_tests !~ /^Standard/
         ActiveSupport.use_standard_json_time_format = class_tests =~ /^Standard/
-        self.class.const_get(class_tests).each do |pair|
+        JSONTest::EncodingTestCases.const_get(class_tests).each do |pair|
           assert_equal pair.last, sorted_json(ActiveSupport::JSON.encode(pair.first))
         end
       ensure
@@ -131,6 +32,8 @@ class TestJSONEncoding < ActiveSupport::TestCase
   end
 
   def test_process_status
+    rubinius_skip "https://github.com/rubinius/rubinius/issues/3334"
+
     # There doesn't seem to be a good way to get a handle on a Process::Status object without actually
     # creating a child process, hence this to populate $?
     system("not_a_real_program_#{SecureRandom.hex}")
@@ -146,6 +49,13 @@ class TestJSONEncoding < ActiveSupport::TestCase
     assert_equal %({\"a\":\"b\",\"c\":\"d\"}), sorted_json(ActiveSupport::JSON.encode(:a => :b, :c => :d))
   end
 
+  def test_hash_keys_encoding
+    ActiveSupport.escape_html_entities_in_json = true
+    assert_equal "{\"\\u003c\\u003e\":\"\\u003c\\u003e\"}", ActiveSupport::JSON.encode("<>" => "<>")
+  ensure
+    ActiveSupport.escape_html_entities_in_json = false
+  end
+
   def test_utf8_string_encoded_properly
     result = ActiveSupport::JSON.encode('€2.99')
     assert_equal '"€2.99"', result
@@ -216,7 +126,7 @@ class TestJSONEncoding < ActiveSupport::TestCase
   end
 
   def test_hash_like_with_options
-    h = Hashlike.new
+    h = JSONTest::Hashlike.new
     json = h.to_json :only => [:foo]
 
     assert_equal({"foo"=>"hello"}, JSON.parse(json))
@@ -337,6 +247,15 @@ class TestJSONEncoding < ActiveSupport::TestCase
     assert_equal(%([{"address":{"city":"London"}},{"address":{"city":"Paris"}}]), json)
   end
 
+  class CustomWithOptions
+    attr_accessor :foo, :bar
+
+    def as_json(options={})
+      options[:only] = %w(foo bar)
+      super(options)
+    end
+  end
+
   def test_hash_to_json_should_not_keep_options_around
     f = CustomWithOptions.new
     f.foo = "hello"
@@ -357,6 +276,12 @@ class TestJSONEncoding < ActiveSupport::TestCase
                   {"foo"=>"other_foo","test"=>"other_test"}], ActiveSupport::JSON.decode(array.to_json))
   end
 
+  class OptionsTest
+    def as_json(options = :default)
+      options
+    end
+  end
+
   def test_hash_as_json_without_options
     json = { foo: OptionsTest.new }.as_json
     assert_equal({"foo" => :default}, json)
@@ -404,6 +329,19 @@ class TestJSONEncoding < ActiveSupport::TestCase
     assert_equal false, false.as_json
   end
 
+  class HashWithAsJson < Hash
+    attr_accessor :as_json_called
+
+    def initialize(*)
+      super
+    end
+
+    def as_json(options={})
+      @as_json_called = true
+      super
+    end
+  end
+
   def test_json_gem_dump_by_passing_active_support_encoder
     h = HashWithAsJson.new
     h[:foo] = "hello"
diff --git a/activesupport/test/json/encoding_test_cases.rb b/activesupport/test/json/encoding_test_cases.rb
new file mode 100644
index 0000000000..0159ba8606
--- /dev/null
+++ b/activesupport/test/json/encoding_test_cases.rb
@@ -0,0 +1,88 @@
+require 'bigdecimal'
+
+module JSONTest
+  class Foo
+    def initialize(a, b)
+      @a, @b = a, b
+    end
+  end
+
+  class Hashlike
+    def to_hash
+      { :foo => "hello", :bar => "world" }
+    end
+  end
+
+  class Custom
+    def initialize(serialized)
+      @serialized = serialized
+    end
+
+    def as_json(options = nil)
+      @serialized
+    end
+  end
+
+  class MyStruct < Struct.new(:name, :value)
+    def initialize(*)
+      @unused = "unused instance variable"
+      super
+    end
+  end
+
+  module EncodingTestCases
+    TrueTests     = [[ true,  %(true)  ]]
+    FalseTests    = [[ false, %(false) ]]
+    NilTests      = [[ nil,   %(null)  ]]
+    NumericTests  = [[ 1,     %(1)     ],
+                     [ 2.5,   %(2.5)   ],
+                     [ 0.0/0.0,   %(null) ],
+                     [ 1.0/0.0,   %(null) ],
+                     [ -1.0/0.0,  %(null) ],
+                     [ BigDecimal('0.0')/BigDecimal('0.0'),  %(null) ],
+                     [ BigDecimal('2.5'), %("#{BigDecimal('2.5')}") ]]
+
+    StringTests   = [[ 'this is the <string>',     %("this is the \\u003cstring\\u003e")],
+                     [ 'a "string" with quotes & an ampersand', %("a \\"string\\" with quotes \\u0026 an ampersand") ],
+                     [ 'http://test.host/posts/1', %("http://test.host/posts/1")],
+                     [ "Control characters: \x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\u2028\u2029",
+                       %("Control characters: \\u0000\\u0001\\u0002\\u0003\\u0004\\u0005\\u0006\\u0007\\b\\t\\n\\u000b\\f\\r\\u000e\\u000f\\u0010\\u0011\\u0012\\u0013\\u0014\\u0015\\u0016\\u0017\\u0018\\u0019\\u001a\\u001b\\u001c\\u001d\\u001e\\u001f\\u2028\\u2029") ]]
+
+    ArrayTests    = [[ ['a', 'b', 'c'],          %([\"a\",\"b\",\"c\"])        ],
+                     [ [1, 'a', :b, nil, false], %([1,\"a\",\"b\",null,false]) ]]
+
+    HashTests     = [[ {foo: "bar"}, %({\"foo\":\"bar\"}) ],
+                     [ {1 => 1, 2 => 'a', 3 => :b, 4 => nil, 5 => false}, %({\"1\":1,\"2\":\"a\",\"3\":\"b\",\"4\":null,\"5\":false}) ]]
+
+    RangeTests    = [[ 1..2,     %("1..2")],
+                     [ 1...2,    %("1...2")],
+                     [ 1.5..2.5, %("1.5..2.5")]]
+
+    SymbolTests   = [[ :a,     %("a")    ],
+                     [ :this,  %("this") ],
+                     [ :"a b", %("a b")  ]]
+
+    ObjectTests   = [[ Foo.new(1, 2), %({\"a\":1,\"b\":2}) ]]
+    HashlikeTests = [[ Hashlike.new, %({\"bar\":\"world\",\"foo\":\"hello\"}) ]]
+    StructTests   = [[ MyStruct.new(:foo, "bar"), %({\"name\":\"foo\",\"value\":\"bar\"}) ],
+                     [ MyStruct.new(nil, nil), %({\"name\":null,\"value\":null}) ]]
+    CustomTests   = [[ Custom.new("custom"), '"custom"' ],
+                     [ Custom.new(nil), 'null' ],
+                     [ Custom.new(:a), '"a"' ],
+                     [ Custom.new([ :foo, "bar" ]), '["foo","bar"]' ],
+                     [ Custom.new({ :foo => "hello", :bar => "world" }), '{"bar":"world","foo":"hello"}' ],
+                     [ Custom.new(Hashlike.new), '{"bar":"world","foo":"hello"}' ],
+                     [ Custom.new(Custom.new(Custom.new(:a))), '"a"' ]]
+
+    RegexpTests   = [[ /^a/, '"(?-mix:^a)"' ], [/^\w{1,2}[a-z]+/ix, '"(?ix-m:^\\\\w{1,2}[a-z]+)"']]
+
+    DateTests     = [[ Date.new(2005,2,1), %("2005/02/01") ]]
+    TimeTests     = [[ Time.utc(2005,2,1,15,15,10), %("2005/02/01 15:15:10 +0000") ]]
+    DateTimeTests = [[ DateTime.civil(2005,2,1,15,15,10), %("2005/02/01 15:15:10 +0000") ]]
+
+    StandardDateTests     = [[ Date.new(2005,2,1), %("2005-02-01") ]]
+    StandardTimeTests     = [[ Time.utc(2005,2,1,15,15,10), %("2005-02-01T15:15:10.000Z") ]]
+    StandardDateTimeTests = [[ DateTime.civil(2005,2,1,15,15,10), %("2005-02-01T15:15:10.000+00:00") ]]
+    StandardStringTests   = [[ 'this is the <string>', %("this is the <string>")]]
+  end
+end
diff --git a/activesupport/test/log_subscriber_test.rb b/activesupport/test/log_subscriber_test.rb
index 2a0e8d20ed..998a6887c5 100644
--- a/activesupport/test/log_subscriber_test.rb
+++ b/activesupport/test/log_subscriber_test.rb
@@ -82,10 +82,11 @@ class SyncLogSubscriberTest < ActiveSupport::TestCase
 
   def test_does_not_send_the_event_if_logger_is_nil
     ActiveSupport::LogSubscriber.logger = nil
-    @log_subscriber.expects(:some_event).never
-    ActiveSupport::LogSubscriber.attach_to :my_log_subscriber, @log_subscriber
-    instrument "some_event.my_log_subscriber"
-    wait
+    assert_not_called(@log_subscriber, :some_event) do
+      ActiveSupport::LogSubscriber.attach_to :my_log_subscriber, @log_subscriber
+      instrument "some_event.my_log_subscriber"
+      wait
+    end
   end
 
   def test_does_not_fail_with_non_namespaced_events
diff --git a/activesupport/test/message_verifier_test.rb b/activesupport/test/message_verifier_test.rb
index 6c3519df9a..668d78492e 100644
--- a/activesupport/test/message_verifier_test.rb
+++ b/activesupport/test/message_verifier_test.rb
@@ -24,6 +24,7 @@ class MessageVerifierTest < ActiveSupport::TestCase
     data, hash = @verifier.generate(@data).split("--")
     assert !@verifier.valid_message?(nil)
     assert !@verifier.valid_message?("")
+    assert !@verifier.valid_message?("\xff") # invalid encoding
     assert !@verifier.valid_message?("#{data.reverse}--#{hash}")
     assert !@verifier.valid_message?("#{data}--#{hash.reverse}")
     assert !@verifier.valid_message?("purejunk")
diff --git a/activesupport/test/multibyte_chars_test.rb b/activesupport/test/multibyte_chars_test.rb
index 94748dd991..8d4d9d736c 100644
--- a/activesupport/test/multibyte_chars_test.rb
+++ b/activesupport/test/multibyte_chars_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'multibyte_test_helpers'
 require 'active_support/core_ext/string/multibyte'
@@ -414,12 +413,24 @@ class MultibyteCharsUTF8BehaviourTest < ActiveSupport::TestCase
     assert_equal 'にち', @chars.slice!(1..2)
   end
 
+  def test_slice_bang_returns_nil_on_out_of_bound_arguments
+    assert_equal nil, @chars.mb_chars.slice!(9..10)
+  end
+
   def test_slice_bang_removes_the_slice_from_the_receiver
     chars = 'úüù'.mb_chars
     chars.slice!(0,2)
     assert_equal 'ù', chars
   end
 
+  def test_slice_bang_returns_nil_and_does_not_modify_receiver_if_out_of_bounds
+    string = 'úüù'
+    chars = string.mb_chars
+    assert_nil chars.slice!(4, 5)
+    assert_equal 'úüù', chars
+    assert_equal 'úüù', string
+  end
+
   def test_slice_should_throw_exceptions_on_invalid_arguments
     assert_raise(TypeError) { @chars.slice(2..3, 1) }
     assert_raise(TypeError) { @chars.slice(1, 2..3) }
diff --git a/activesupport/test/multibyte_conformance_test.rb b/activesupport/test/multibyte_conformance_test.rb
index f7bd21c8ab..2a885e32bf 100644
--- a/activesupport/test/multibyte_conformance_test.rb
+++ b/activesupport/test/multibyte_conformance_test.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 require 'abstract_unit'
 require 'multibyte_test_helpers'
 
diff --git a/activesupport/test/multibyte_proxy_test.rb b/activesupport/test/multibyte_proxy_test.rb
index d8ffd7ca9c..360cf57302 100644
--- a/activesupport/test/multibyte_proxy_test.rb
+++ b/activesupport/test/multibyte_proxy_test.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 require 'abstract_unit'
 
 class MultibyteProxyText < ActiveSupport::TestCase
diff --git a/activesupport/test/multibyte_test_helpers.rb b/activesupport/test/multibyte_test_helpers.rb
index 90af2dadd4..58cf5488cd 100644
--- a/activesupport/test/multibyte_test_helpers.rb
+++ b/activesupport/test/multibyte_test_helpers.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 module MultibyteTestHelpers
   UNICODE_STRING = 'こにちわ'.freeze
   ASCII_STRING = 'ohayo'.freeze
diff --git a/activesupport/test/multibyte_unicode_database_test.rb b/activesupport/test/multibyte_unicode_database_test.rb
index bec65daf50..dd33641ec2 100644
--- a/activesupport/test/multibyte_unicode_database_test.rb
+++ b/activesupport/test/multibyte_unicode_database_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 
@@ -12,8 +11,9 @@ class MultibyteUnicodeDatabaseTest < ActiveSupport::TestCase
 
   UnicodeDatabase::ATTRIBUTES.each do |attribute|
     define_method "test_lazy_loading_on_attribute_access_of_#{attribute}" do
-      @ucd.expects(:load)
-      @ucd.send(attribute)
+      assert_called(@ucd, :load) do
+        @ucd.send(attribute)
+      end
     end
   end
 
diff --git a/activesupport/test/number_helper_test.rb b/activesupport/test/number_helper_test.rb
index 50d84a9470..7f62d7c0b3 100644
--- a/activesupport/test/number_helper_test.rb
+++ b/activesupport/test/number_helper_test.rb
@@ -83,6 +83,14 @@ module ActiveSupport
           assert_equal("98a%", number_helper.number_to_percentage("98a"))
           assert_equal("NaN%", number_helper.number_to_percentage(Float::NAN))
           assert_equal("Inf%", number_helper.number_to_percentage(Float::INFINITY))
+          assert_equal("NaN%", number_helper.number_to_percentage(Float::NAN, precision: 0))
+          assert_equal("Inf%", number_helper.number_to_percentage(Float::INFINITY, precision: 0))
+          assert_equal("NaN%", number_helper.number_to_percentage(Float::NAN, precision: 1))
+          assert_equal("Inf%", number_helper.number_to_percentage(Float::INFINITY, precision: 1))
+          assert_equal("1000%", number_helper.number_to_percentage(1000, precision: nil))
+          assert_equal("1000%", number_helper.number_to_percentage(1000, precision: nil))
+          assert_equal("1000.1%", number_helper.number_to_percentage(1000.1, precision: nil))
+          assert_equal("-0.13 %", number_helper.number_to_percentage("-0.13", precision: nil, format: "%n %"))
         end
       end
 
@@ -98,6 +106,7 @@ module ActiveSupport
           assert_equal("123,456,789.78901", number_helper.number_to_delimited(123456789.78901))
           assert_equal("0.78901", number_helper.number_to_delimited(0.78901))
           assert_equal("123,456.78", number_helper.number_to_delimited("123456.78"))
+          assert_equal("1,23,456.78", number_helper.number_to_delimited("123456.78", delimiter_pattern: /(\d+?)(?=(\d\d)+(\d)(?!\d))/))
           assert_equal("123,456.78", number_helper.number_to_delimited("123456.78".html_safe))
         end
       end
@@ -226,15 +235,17 @@ module ActiveSupport
       end
 
       def test_number_to_human_size_with_si_prefix
-        [@instance_with_helpers, TestClassWithClassNumberHelpers, ActiveSupport::NumberHelper].each do |number_helper|
-          assert_equal '3 Bytes',    number_helper.number_to_human_size(3.14159265, :prefix => :si)
-          assert_equal '123 Bytes',  number_helper.number_to_human_size(123.0, :prefix => :si)
-          assert_equal '123 Bytes',  number_helper.number_to_human_size(123, :prefix => :si)
-          assert_equal '1.23 KB',    number_helper.number_to_human_size(1234, :prefix => :si)
-          assert_equal '12.3 KB',    number_helper.number_to_human_size(12345, :prefix => :si)
-          assert_equal '1.23 MB',    number_helper.number_to_human_size(1234567, :prefix => :si)
-          assert_equal '1.23 GB',    number_helper.number_to_human_size(1234567890, :prefix => :si)
-          assert_equal '1.23 TB',    number_helper.number_to_human_size(1234567890123, :prefix => :si)
+        assert_deprecated do
+          [@instance_with_helpers, TestClassWithClassNumberHelpers, ActiveSupport::NumberHelper].each do |number_helper|
+            assert_equal '3 Bytes',    number_helper.number_to_human_size(3.14159265, :prefix => :si)
+            assert_equal '123 Bytes',  number_helper.number_to_human_size(123.0, :prefix => :si)
+            assert_equal '123 Bytes',  number_helper.number_to_human_size(123, :prefix => :si)
+            assert_equal '1.23 KB',    number_helper.number_to_human_size(1234, :prefix => :si)
+            assert_equal '12.3 KB',    number_helper.number_to_human_size(12345, :prefix => :si)
+            assert_equal '1.23 MB',    number_helper.number_to_human_size(1234567, :prefix => :si)
+            assert_equal '1.23 GB',    number_helper.number_to_human_size(1234567890, :prefix => :si)
+            assert_equal '1.23 TB',    number_helper.number_to_human_size(1234567890123, :prefix => :si)
+          end
         end
       end
 
@@ -285,6 +296,8 @@ module ActiveSupport
           assert_equal '1.2346 Million', number_helper.number_to_human(1234567, :precision => 4, :significant => false)
           assert_equal '1,2 Million', number_helper.number_to_human(1234567, :precision => 1, :significant => false, :separator => ',')
           assert_equal '1 Million', number_helper.number_to_human(1234567, :precision => 0, :significant => true, :separator => ',') #significant forced to false
+          assert_equal '1 Million', number_helper.number_to_human(999999)
+          assert_equal '1 Billion', number_helper.number_to_human(999999999)
         end
       end
 
diff --git a/activesupport/test/ordered_options_test.rb b/activesupport/test/ordered_options_test.rb
index fdc745b23b..18767a3536 100644
--- a/activesupport/test/ordered_options_test.rb
+++ b/activesupport/test/ordered_options_test.rb
@@ -85,4 +85,19 @@ class OrderedOptionsTest < ActiveSupport::TestCase
     assert_equal 42, a.method(:blah=).call(42)
     assert_equal 42, a.method(:blah).call
   end
+
+  def test_raises_with_bang
+    a = ActiveSupport::OrderedOptions.new
+    a[:foo] = :bar
+    assert a.respond_to?(:foo!)
+
+    assert_nothing_raised { a.foo! }
+    assert_equal a.foo, a.foo!
+
+    assert_raises(KeyError) do
+      a.foo = nil
+      a.foo!
+    end
+    assert_raises(KeyError) { a.non_existing_key! }
+  end
 end
diff --git a/activesupport/test/safe_buffer_test.rb b/activesupport/test/safe_buffer_test.rb
index 4532152996..18fb6d2fbf 100644
--- a/activesupport/test/safe_buffer_test.rb
+++ b/activesupport/test/safe_buffer_test.rb
@@ -61,6 +61,13 @@ class SafeBufferTest < ActiveSupport::TestCase
     assert_equal({'str' => str}, YAML.load(yaml))
   end
 
+  test "Should work with primitive-like-strings in to_yaml conversion" do
+    assert_equal 'true',  YAML.load(ActiveSupport::SafeBuffer.new('true').to_yaml)
+    assert_equal 'false', YAML.load(ActiveSupport::SafeBuffer.new('false').to_yaml)
+    assert_equal '1',     YAML.load(ActiveSupport::SafeBuffer.new('1').to_yaml)
+    assert_equal '1.1',   YAML.load(ActiveSupport::SafeBuffer.new('1.1').to_yaml)
+  end
+
   test "Should work with underscore" do
     str = "MyTest".html_safe.underscore
     assert_equal "my_test", str
diff --git a/activesupport/test/share_lock_test.rb b/activesupport/test/share_lock_test.rb
new file mode 100644
index 0000000000..ad41db608b
--- /dev/null
+++ b/activesupport/test/share_lock_test.rb
@@ -0,0 +1,333 @@
+require 'abstract_unit'
+require 'concurrent/atomics'
+require 'active_support/concurrency/share_lock'
+
+class ShareLockTest < ActiveSupport::TestCase
+  def setup
+    @lock = ActiveSupport::Concurrency::ShareLock.new
+  end
+
+  def test_reentrancy
+    thread = Thread.new do
+      @lock.sharing   { @lock.sharing   {} }
+      @lock.exclusive { @lock.exclusive {} }
+    end
+    assert_threads_not_stuck thread
+  end
+
+  def test_sharing_doesnt_block
+    with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_latch|
+      assert_threads_not_stuck(Thread.new {@lock.sharing {} })
+    end
+  end
+
+  def test_sharing_blocks_exclusive
+    with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_release_latch|
+      @lock.exclusive(no_wait: true) { flunk } # polling should fail
+      exclusive_thread = Thread.new { @lock.exclusive {} }
+      assert_threads_stuck_but_releasable_by_latch exclusive_thread, sharing_thread_release_latch
+    end
+  end
+
+  def test_exclusive_blocks_sharing
+    with_thread_waiting_in_lock_section(:exclusive) do |exclusive_thread_release_latch|
+      sharing_thread = Thread.new { @lock.sharing {} }
+      assert_threads_stuck_but_releasable_by_latch sharing_thread, exclusive_thread_release_latch
+    end
+  end
+
+  def test_multiple_exlusives_are_able_to_progress
+    with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_release_latch|
+      exclusive_threads = (1..2).map do
+        Thread.new do
+          @lock.exclusive {}
+        end
+      end
+
+      assert_threads_stuck_but_releasable_by_latch exclusive_threads, sharing_thread_release_latch
+    end
+  end
+
+  def test_sharing_is_upgradeable_to_exclusive
+    upgrading_thread = Thread.new do
+      @lock.sharing do
+        @lock.exclusive {}
+      end
+    end
+    assert_threads_not_stuck upgrading_thread
+  end
+
+  def test_exclusive_upgrade_waits_for_other_sharers_to_leave
+    with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_release_latch|
+      in_sharing = Concurrent::CountDownLatch.new
+
+      upgrading_thread = Thread.new do
+        @lock.sharing do
+          in_sharing.count_down
+          @lock.exclusive {}
+        end
+      end
+
+      in_sharing.wait
+      assert_threads_stuck_but_releasable_by_latch upgrading_thread, sharing_thread_release_latch
+    end
+  end
+
+  def test_exclusive_matching_purpose
+    [true, false].each do |use_upgrading|
+      with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_release_latch|
+        exclusive_threads = (1..2).map do
+          Thread.new do
+            @lock.send(use_upgrading ? :sharing : :tap) do
+              @lock.exclusive(purpose: :load, compatible: [:load, :unload]) {}
+            end
+          end
+        end
+
+        assert_threads_stuck_but_releasable_by_latch exclusive_threads, sharing_thread_release_latch
+      end
+    end
+  end
+
+  def test_killed_thread_loses_lock
+    with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_release_latch|
+      thread = Thread.new do
+        @lock.sharing do
+          @lock.exclusive {}
+        end
+      end
+
+      assert_threads_stuck thread
+      thread.kill
+
+      sharing_thread_release_latch.count_down
+
+      thread = Thread.new do
+        @lock.exclusive {}
+      end
+
+      assert_threads_not_stuck thread
+    end
+  end
+
+  def test_exclusive_conflicting_purpose
+    [true, false].each do |use_upgrading|
+      with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_release_latch|
+        begin
+          conflicting_exclusive_threads = [
+            Thread.new do
+              @lock.send(use_upgrading ? :sharing : :tap) do
+                @lock.exclusive(purpose: :red, compatible: [:green, :purple]) {}
+              end
+            end,
+            Thread.new do
+              @lock.send(use_upgrading ? :sharing : :tap) do
+                @lock.exclusive(purpose: :blue, compatible: [:green]) {}
+              end
+            end
+          ]
+
+          assert_threads_stuck conflicting_exclusive_threads # wait for threads to get into their respective `exclusive {}` blocks
+
+          # This thread will be stuck as long as any other thread is in
+          # a sharing block. While it's blocked, it holds no lock, so it
+          # doesn't interfere with any other attempts.
+          no_purpose_thread = Thread.new do
+            @lock.exclusive {}
+          end
+          assert_threads_stuck no_purpose_thread
+
+          # This thread is compatible with both of the "primary"
+          # attempts above. It's initially stuck on the outer share
+          # lock, but as soon as that's released, it can run --
+          # regardless of whether those threads hold share locks.
+          compatible_thread = Thread.new do
+            @lock.exclusive(purpose: :green, compatible: []) {}
+          end
+          assert_threads_stuck compatible_thread
+
+          assert_threads_stuck conflicting_exclusive_threads
+
+          sharing_thread_release_latch.count_down
+
+          assert_threads_not_stuck compatible_thread # compatible thread is now able to squeak through
+
+          if use_upgrading
+            # The "primary" threads both each hold a share lock, and are
+            # mutually incompatible; they're still stuck.
+            assert_threads_stuck conflicting_exclusive_threads
+
+            # The thread without a specified purpose is also stuck; it's
+            # not compatible with anything.
+            assert_threads_stuck no_purpose_thread
+          else
+            # As the primaries didn't hold a share lock, as soon as the
+            # outer one was released, all the exclusive locks are free
+            # to be acquired in turn.
+
+            assert_threads_not_stuck conflicting_exclusive_threads
+            assert_threads_not_stuck no_purpose_thread
+          end
+        ensure
+          conflicting_exclusive_threads.each(&:kill)
+          no_purpose_thread.kill
+        end
+      end
+    end
+  end
+
+  def test_exclusive_ordering
+    scratch_pad       = []
+    scratch_pad_mutex = Mutex.new
+
+    load_params   = [:load,   [:load]]
+    unload_params = [:unload, [:unload, :load]]
+
+    [load_params, load_params, unload_params, unload_params].permutation do |thread_params|
+      with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_release_latch|
+        threads = thread_params.map do |purpose, compatible|
+          Thread.new do
+            @lock.sharing do
+              @lock.exclusive(purpose: purpose, compatible: compatible) do
+                scratch_pad_mutex.synchronize { scratch_pad << purpose }
+              end
+            end
+          end
+        end
+
+        sleep(0.01)
+        scratch_pad_mutex.synchronize { assert_empty scratch_pad }
+
+        sharing_thread_release_latch.count_down
+
+        assert_threads_not_stuck threads
+        scratch_pad_mutex.synchronize do
+          assert_equal [:load, :load, :unload, :unload], scratch_pad
+          scratch_pad.clear
+        end
+      end
+    end
+  end
+
+  def test_in_shared_section_incompatible_non_upgrading_threads_cannot_preempt_upgrading_threads
+    scratch_pad       = []
+    scratch_pad_mutex = Mutex.new
+
+    upgrading_load_params       = [:load,   [:load],          true]
+    non_upgrading_unload_params = [:unload, [:load, :unload], false]
+
+    [upgrading_load_params, non_upgrading_unload_params].permutation do |thread_params|
+      with_thread_waiting_in_lock_section(:sharing) do |sharing_thread_release_latch|
+        threads = thread_params.map do |purpose, compatible, use_upgrading|
+          Thread.new do
+            @lock.send(use_upgrading ? :sharing : :tap) do
+              @lock.exclusive(purpose: purpose, compatible: compatible) do
+                scratch_pad_mutex.synchronize { scratch_pad << purpose }
+              end
+            end
+          end
+        end
+
+        assert_threads_stuck threads
+        scratch_pad_mutex.synchronize { assert_empty scratch_pad }
+
+        sharing_thread_release_latch.count_down
+
+        assert_threads_not_stuck threads
+        scratch_pad_mutex.synchronize do
+          assert_equal [:load, :unload], scratch_pad
+          scratch_pad.clear
+        end
+      end
+    end
+  end
+
+  private
+
+  module CustomAssertions
+    SUFFICIENT_TIMEOUT = 0.2
+
+    private
+
+    def assert_threads_stuck_but_releasable_by_latch(threads, latch)
+      assert_threads_stuck threads
+      latch.count_down
+      assert_threads_not_stuck threads
+    end
+
+    def assert_threads_stuck(threads)
+      sleep(SUFFICIENT_TIMEOUT) # give threads time to do their business
+      assert(Array(threads).all? { |t| t.join(0.001).nil? })
+    end
+
+    def assert_threads_not_stuck(threads)
+      assert(Array(threads).all? { |t| t.join(SUFFICIENT_TIMEOUT) })
+    end
+  end
+
+  class CustomAssertionsTest < ActiveSupport::TestCase
+    include CustomAssertions
+
+    def setup
+      @latch = Concurrent::CountDownLatch.new
+      @thread = Thread.new { @latch.wait }
+    end
+
+    def teardown
+      @latch.count_down
+      @thread.join
+    end
+
+    def test_happy_path
+      assert_threads_stuck_but_releasable_by_latch @thread, @latch
+    end
+
+    def test_detects_stuck_thread
+      assert_raises(Minitest::Assertion) do
+        assert_threads_not_stuck @thread
+      end
+    end
+
+    def test_detects_free_thread
+      @latch.count_down
+      assert_raises(Minitest::Assertion) do
+        assert_threads_stuck @thread
+      end
+    end
+
+    def test_detects_already_released
+      @latch.count_down
+      assert_raises(Minitest::Assertion) do
+        assert_threads_stuck_but_releasable_by_latch @thread, @latch
+      end
+    end
+
+    def test_detects_remains_latched
+      another_latch = Concurrent::CountDownLatch.new
+      assert_raises(Minitest::Assertion) do
+        assert_threads_stuck_but_releasable_by_latch @thread, another_latch
+      end
+    end
+  end
+
+  include CustomAssertions
+
+  def with_thread_waiting_in_lock_section(lock_section)
+    in_section      = Concurrent::CountDownLatch.new
+    section_release = Concurrent::CountDownLatch.new
+
+    stuck_thread = Thread.new do
+      @lock.send(lock_section) do
+        in_section.count_down
+        section_release.wait
+      end
+    end
+
+    in_section.wait
+
+    yield section_release
+  ensure
+    section_release.count_down
+    stuck_thread.join # clean up
+  end
+end
diff --git a/activesupport/test/tagged_logging_test.rb b/activesupport/test/tagged_logging_test.rb
index 03a63e94e8..917fa46c96 100644
--- a/activesupport/test/tagged_logging_test.rb
+++ b/activesupport/test/tagged_logging_test.rb
@@ -72,11 +72,11 @@ class TaggedLoggingTest < ActiveSupport::TestCase
   test "keeps each tag in their own thread" do
     @logger.tagged("BCX") do
       Thread.new do
-        @logger.tagged("OMG") { @logger.info "Cool story bro" }
+        @logger.tagged("OMG") { @logger.info "Cool story" }
       end.join
       @logger.info "Funky time"
     end
-    assert_equal "[OMG] Cool story bro\n[BCX] Funky time\n", @output.string
+    assert_equal "[OMG] Cool story\n[BCX] Funky time\n", @output.string
   end
 
   test "keeps each tag in their own instance" do
@@ -84,11 +84,11 @@ class TaggedLoggingTest < ActiveSupport::TestCase
     @other_logger = ActiveSupport::TaggedLogging.new(MyLogger.new(@other_output))
     @logger.tagged("OMG") do
       @other_logger.tagged("BCX") do
-        @logger.info "Cool story bro"
+        @logger.info "Cool story"
         @other_logger.info "Funky time"
       end
     end
-    assert_equal "[OMG] Cool story bro\n", @output.string
+    assert_equal "[OMG] Cool story\n", @output.string
     assert_equal "[BCX] Funky time\n", @other_output.string
   end
 
@@ -97,11 +97,11 @@ class TaggedLoggingTest < ActiveSupport::TestCase
       Thread.new do
         @logger.tagged("OMG") do
           @logger.flush
-          @logger.info "Cool story bro"
+          @logger.info "Cool story"
         end
       end.join
     end
-    assert_equal "[FLUSHED]\nCool story bro\n", @output.string
+    assert_equal "[FLUSHED]\nCool story\n", @output.string
   end
 
   test "mixed levels of tagging" do
diff --git a/activesupport/test/test_case_test.rb b/activesupport/test/test_case_test.rb
index 151b623171..18228a2ac5 100644
--- a/activesupport/test/test_case_test.rb
+++ b/activesupport/test/test_case_test.rb
@@ -56,6 +56,14 @@ class AssertDifferenceTest < ActiveSupport::TestCase
     end
   end
 
+  def test_assert_difference_retval
+    incremented = assert_difference '@object.num', +1 do
+      @object.increment
+    end
+
+    assert_equal incremented, 1
+  end
+
   def test_assert_difference_with_implicit_difference
     assert_difference '@object.num' do
       @object.increment
@@ -205,15 +213,4 @@ class TestOrderTest < ActiveSupport::TestCase
     assert_equal :random, self.class.test_order
     assert_equal :random, Class.new(ActiveSupport::TestCase).test_order
   end
-
-  def test_i_suck_and_my_tests_are_order_dependent!
-    ActiveSupport::TestCase.test_order = :random
-
-    klass = Class.new(ActiveSupport::TestCase) do
-      i_suck_and_my_tests_are_order_dependent!
-    end
-
-    assert_equal :alpha, klass.test_order
-    assert_equal :random, ActiveSupport::TestCase.test_order
-  end
 end
diff --git a/activesupport/test/testing/file_fixtures_test.rb b/activesupport/test/testing/file_fixtures_test.rb
new file mode 100644
index 0000000000..91b8a9071c
--- /dev/null
+++ b/activesupport/test/testing/file_fixtures_test.rb
@@ -0,0 +1,28 @@
+require 'abstract_unit'
+
+class FileFixturesTest < ActiveSupport::TestCase
+  self.file_fixture_path = File.expand_path("../../file_fixtures", __FILE__)
+
+  test "#file_fixture returns Pathname to file fixture" do
+    path = file_fixture("sample.txt")
+    assert_kind_of Pathname, path
+    assert_match %r{activesupport/test/file_fixtures/sample.txt$}, path.to_s
+  end
+
+  test "raises an exception when the fixture file does not exist" do
+    e = assert_raises(ArgumentError) do
+      file_fixture("nope")
+    end
+    assert_match(/^the directory '[^']+test\/file_fixtures' does not contain a file named 'nope'$/, e.message)
+  end
+end
+
+class FileFixturesPathnameDirectoryTest < ActiveSupport::TestCase
+  self.file_fixture_path = Pathname.new(File.expand_path("../../file_fixtures", __FILE__))
+
+  test "#file_fixture_path returns Pathname to file fixture" do
+    path = file_fixture("sample.txt")
+    assert_kind_of Pathname, path
+    assert_match %r{activesupport/test/file_fixtures/sample.txt$}, path.to_s
+  end
+end
diff --git a/activesupport/test/testing/method_call_assertions_test.rb b/activesupport/test/testing/method_call_assertions_test.rb
new file mode 100644
index 0000000000..3e5ba7c079
--- /dev/null
+++ b/activesupport/test/testing/method_call_assertions_test.rb
@@ -0,0 +1,123 @@
+require 'abstract_unit'
+require 'active_support/testing/method_call_assertions'
+
+class MethodCallAssertionsTest < ActiveSupport::TestCase
+  include ActiveSupport::Testing::MethodCallAssertions
+
+  class Level
+    def increment; 1; end
+    def decrement; end
+    def <<(arg); end
+  end
+
+  setup do
+    @object = Level.new
+  end
+
+  def test_assert_called_with_defaults_to_expect_once
+    assert_called @object, :increment do
+      @object.increment
+    end
+  end
+
+  def test_assert_called_more_than_once
+    assert_called(@object, :increment, times: 2) do
+      @object.increment
+      @object.increment
+    end
+  end
+
+  def test_assert_called_method_with_arguments
+    assert_called(@object, :<<) do
+      @object << 2
+    end
+  end
+
+  def test_assert_called_returns
+    assert_called(@object, :increment, returns: 10) do
+      assert_equal 10, @object.increment
+    end
+  end
+
+  def test_assert_called_failure
+    error = assert_raises(Minitest::Assertion) do
+      assert_called(@object, :increment) do
+        # Call nothing...
+      end
+    end
+
+    assert_equal "Expected increment to be called 1 times, but was called 0 times.\nExpected: 1\n  Actual: 0", error.message
+  end
+
+  def test_assert_called_with_message
+    error = assert_raises(Minitest::Assertion) do
+      assert_called(@object, :increment, 'dang it') do
+        # Call nothing...
+      end
+    end
+
+    assert_match(/dang it.\nExpected increment/, error.message)
+  end
+
+  def test_assert_called_with
+    assert_called_with(@object, :increment) do
+      @object.increment
+    end
+  end
+
+  def test_assert_called_with_arguments
+    assert_called_with(@object, :<<, [ 2 ]) do
+      @object << 2
+    end
+  end
+
+  def test_assert_called_with_failure
+    assert_raises(MockExpectationError) do
+      assert_called_with(@object, :<<, [ 4567 ]) do
+        @object << 2
+      end
+    end
+  end
+
+  def test_assert_called_with_returns
+    assert_called_with(@object, :increment, returns: 1) do
+      @object.increment
+    end
+  end
+
+  def test_assert_called_with_multiple_expected_arguments
+    assert_called_with(@object, :<<, [ [ 1 ], [ 2 ] ]) do
+      @object << 1
+      @object << 2
+    end
+  end
+
+  def test_assert_not_called
+    assert_not_called(@object, :decrement) do
+      @object.increment
+    end
+  end
+
+  def test_assert_not_called_failure
+    error = assert_raises(Minitest::Assertion) do
+      assert_not_called(@object, :increment) do
+        @object.increment
+      end
+    end
+
+    assert_equal "Expected increment to be called 0 times, but was called 1 times.\nExpected: 0\n  Actual: 1", error.message
+  end
+
+  def test_stub_any_instance
+    stub_any_instance(Level) do |instance|
+      assert_equal instance, Level.new
+    end
+  end
+
+  def test_stub_any_instance_with_instance
+    stub_any_instance(Level, instance: @object) do |instance|
+      assert_equal @object, instance
+      assert_equal instance, Level.new
+    end
+  end
+end
diff --git a/activesupport/test/time_travel_test.rb b/activesupport/test/time_travel_test.rb
index 065539671d..59c3e52c2f 100644
--- a/activesupport/test/time_travel_test.rb
+++ b/activesupport/test/time_travel_test.rb
@@ -1,72 +1,90 @@
 require 'abstract_unit'
-require 'active_support/core_ext/date'
+require 'active_support/core_ext/date_time'
 require 'active_support/core_ext/numeric/time'
 
 class TimeTravelTest < ActiveSupport::TestCase
-  setup do
-    Time.stubs now: Time.now
-  end
-
   teardown do
     travel_back
   end
 
   def test_time_helper_travel
-    expected_time = Time.now + 1.day
-    travel 1.day
-
-    assert_equal expected_time.to_s(:db), Time.now.to_s(:db)
-    assert_equal expected_time.to_date, Date.today
-  end
-
-  def test_time_helper_travel_with_block
-    expected_time = Time.now + 1.day
+    Time.stub(:now, Time.now) do
+      expected_time = Time.now + 1.day
+      travel 1.day
 
-    travel 1.day do
       assert_equal expected_time.to_s(:db), Time.now.to_s(:db)
       assert_equal expected_time.to_date, Date.today
+      assert_equal expected_time.to_datetime.to_s(:db), DateTime.now.to_s(:db)
     end
-
-    assert_not_equal expected_time.to_s(:db), Time.now.to_s(:db)
-    assert_not_equal expected_time.to_date, Date.today
   end
 
-  def test_time_helper_travel_to
-    expected_time = Time.new(2004, 11, 24, 01, 04, 44)
-    travel_to expected_time
-
-    assert_equal expected_time, Time.now
-    assert_equal Date.new(2004, 11, 24), Date.today
+  def test_time_helper_travel_with_block
+    Time.stub(:now, Time.now) do
+      expected_time = Time.now + 1.day
+
+      travel 1.day do
+        assert_equal expected_time.to_s(:db), Time.now.to_s(:db)
+        assert_equal expected_time.to_date, Date.today
+        assert_equal expected_time.to_datetime.to_s(:db), DateTime.now.to_s(:db)
+      end
+
+      assert_not_equal expected_time.to_s(:db), Time.now.to_s(:db)
+      assert_not_equal expected_time.to_date, Date.today
+      assert_not_equal expected_time.to_datetime.to_s(:db), DateTime.now.to_s(:db)
+    end
   end
 
-  def test_time_helper_travel_to_with_block
-    expected_time = Time.new(2004, 11, 24, 01, 04, 44)
+  def test_time_helper_travel_to
+    Time.stub(:now, Time.now) do
+      expected_time = Time.new(2004, 11, 24, 01, 04, 44)
+      travel_to expected_time
 
-    travel_to expected_time do
       assert_equal expected_time, Time.now
       assert_equal Date.new(2004, 11, 24), Date.today
+      assert_equal expected_time.to_datetime, DateTime.now
     end
+  end
 
-    assert_not_equal expected_time, Time.now
-    assert_not_equal Date.new(2004, 11, 24), Date.today
+  def test_time_helper_travel_to_with_block
+    Time.stub(:now, Time.now) do
+      expected_time = Time.new(2004, 11, 24, 01, 04, 44)
+
+      travel_to expected_time do
+        assert_equal expected_time, Time.now
+        assert_equal Date.new(2004, 11, 24), Date.today
+        assert_equal expected_time.to_datetime, DateTime.now
+      end
+
+      assert_not_equal expected_time, Time.now
+      assert_not_equal Date.new(2004, 11, 24), Date.today
+      assert_not_equal expected_time.to_datetime, DateTime.now
+    end
   end
 
   def test_time_helper_travel_back
-    expected_time = Time.new(2004, 11, 24, 01, 04, 44)
+    Time.stub(:now, Time.now) do
+      expected_time = Time.new(2004, 11, 24, 01, 04, 44)
 
-    travel_to expected_time
-    assert_equal expected_time, Time.now
-    assert_equal Date.new(2004, 11, 24), Date.today
-    travel_back
+      travel_to expected_time
+      assert_equal expected_time, Time.now
+      assert_equal Date.new(2004, 11, 24), Date.today
+      assert_equal expected_time.to_datetime, DateTime.now
+      travel_back
 
-    assert_not_equal expected_time, Time.now
-    assert_not_equal Date.new(2004, 11, 24), Date.today
+      assert_not_equal expected_time, Time.now
+      assert_not_equal Date.new(2004, 11, 24), Date.today
+      assert_not_equal expected_time.to_datetime, DateTime.now
+    end
   end
 
   def test_travel_to_will_reset_the_usec_to_avoid_mysql_rouding
-    travel_to Time.utc(2014, 10, 10, 10, 10, 50, 999999) do
-      assert_equal 50, Time.now.sec
-      assert_equal 0, Time.now.usec
+    Time.stub(:now, Time.now) do
+      travel_to Time.utc(2014, 10, 10, 10, 10, 50, 999999) do
+        assert_equal 50, Time.now.sec
+        assert_equal 0, Time.now.usec
+        assert_equal 50, DateTime.now.sec
+        assert_equal 0, DateTime.now.usec
+      end
     end
   end
 end
diff --git a/activesupport/test/time_zone_test.rb b/activesupport/test/time_zone_test.rb
index cd7e184cda..00d40c4497 100644
--- a/activesupport/test/time_zone_test.rb
+++ b/activesupport/test/time_zone_test.rb
@@ -1,6 +1,7 @@
 require 'abstract_unit'
 require 'active_support/time'
 require 'time_zone_test_helpers'
+require 'yaml'
 
 class TimeZoneTest < ActiveSupport::TestCase
   include TimeZoneTestHelpers
@@ -252,9 +253,10 @@ class TimeZoneTest < ActiveSupport::TestCase
 
   def test_parse_with_incomplete_date
     zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
-    zone.stubs(:now).returns zone.local(1999,12,31)
-    twz = zone.parse('19:00:00')
-    assert_equal Time.utc(1999,12,31,19), twz.time
+    zone.stub(:now, zone.local(1999,12,31)) do
+      twz = zone.parse('19:00:00')
+      assert_equal Time.utc(1999,12,31,19), twz.time
+    end
   end
 
   def test_parse_with_day_omitted
@@ -284,9 +286,10 @@ class TimeZoneTest < ActiveSupport::TestCase
 
   def test_parse_with_missing_time_components
     zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
-    zone.stubs(:now).returns zone.local(1999, 12, 31, 12, 59, 59)
-    twz = zone.parse('2012-12-01')
-    assert_equal Time.utc(2012, 12, 1), twz.time
+    zone.stub(:now, zone.local(1999, 12, 31, 12, 59, 59)) do
+      twz = zone.parse('2012-12-01')
+      assert_equal Time.utc(2012, 12, 1), twz.time
+    end
   end
 
   def test_parse_with_javascript_date
@@ -311,6 +314,80 @@ class TimeZoneTest < ActiveSupport::TestCase
     end
   end
 
+  def test_strptime
+    zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+    twz = zone.strptime('1999-12-31 12:00:00', '%Y-%m-%d %H:%M:%S')
+    assert_equal Time.utc(1999,12,31,17), twz
+    assert_equal Time.utc(1999,12,31,12), twz.time
+    assert_equal Time.utc(1999,12,31,17), twz.utc
+    assert_equal zone, twz.time_zone
+  end
+
+  def test_strptime_with_nondefault_time_zone
+    with_tz_default ActiveSupport::TimeZone['Pacific Time (US & Canada)'] do
+      zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+      twz = zone.strptime('1999-12-31 12:00:00', '%Y-%m-%d %H:%M:%S')
+      assert_equal Time.utc(1999,12,31,17), twz
+      assert_equal Time.utc(1999,12,31,12), twz.time
+      assert_equal Time.utc(1999,12,31,17), twz.utc
+      assert_equal zone, twz.time_zone
+    end
+  end
+
+  def test_strptime_with_explicit_time_zone_as_abbrev
+    zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+    twz = zone.strptime('1999-12-31 12:00:00 PST', '%Y-%m-%d %H:%M:%S %Z')
+    assert_equal Time.utc(1999,12,31,20), twz
+    assert_equal Time.utc(1999,12,31,15), twz.time
+    assert_equal Time.utc(1999,12,31,20), twz.utc
+    assert_equal zone, twz.time_zone
+  end
+
+  def test_strptime_with_explicit_time_zone_as_h_offset
+    zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+    twz = zone.strptime('1999-12-31 12:00:00 -08', '%Y-%m-%d %H:%M:%S %:::z')
+    assert_equal Time.utc(1999,12,31,20), twz
+    assert_equal Time.utc(1999,12,31,15), twz.time
+    assert_equal Time.utc(1999,12,31,20), twz.utc
+    assert_equal zone, twz.time_zone
+  end
+
+  def test_strptime_with_explicit_time_zone_as_hm_offset
+    zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+    twz = zone.strptime('1999-12-31 12:00:00 -08:00', '%Y-%m-%d %H:%M:%S %:z')
+    assert_equal Time.utc(1999,12,31,20), twz
+    assert_equal Time.utc(1999,12,31,15), twz.time
+    assert_equal Time.utc(1999,12,31,20), twz.utc
+    assert_equal zone, twz.time_zone
+  end
+
+  def test_strptime_with_explicit_time_zone_as_hms_offset
+    zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+    twz = zone.strptime('1999-12-31 12:00:00 -08:00:00', '%Y-%m-%d %H:%M:%S %::z')
+    assert_equal Time.utc(1999,12,31,20), twz
+    assert_equal Time.utc(1999,12,31,15), twz.time
+    assert_equal Time.utc(1999,12,31,20), twz.utc
+    assert_equal zone, twz.time_zone
+  end
+
+  def test_strptime_with_almost_explicit_time_zone
+    zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+    twz = zone.strptime('1999-12-31 12:00:00 %Z', '%Y-%m-%d %H:%M:%S %%Z')
+    assert_equal Time.utc(1999,12,31,17), twz
+    assert_equal Time.utc(1999,12,31,12), twz.time
+    assert_equal Time.utc(1999,12,31,17), twz.utc
+    assert_equal zone, twz.time_zone
+  end
+
+  def test_strptime_with_day_omitted
+    with_env_tz 'US/Eastern' do
+      zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+      assert_equal Time.local(2000, 2, 1), zone.strptime('Feb', '%b', Time.local(2000, 1, 1))
+      assert_equal Time.local(2005, 2, 1), zone.strptime('Feb 2005', '%b %Y', Time.local(2000, 1, 1))
+      assert_equal Time.local(2005, 2, 2), zone.strptime('2 Feb 2005', '%e %b %Y', Time.local(2000, 1, 1))
+    end
+  end
+
   def test_utc_offset_lazy_loaded_from_tzinfo_when_not_passed_in_to_initialize
     tzinfo = TZInfo::Timezone.get('America/New_York')
     zone = ActiveSupport::TimeZone.create(tzinfo.name, nil, tzinfo)
@@ -402,8 +479,7 @@ class TimeZoneTest < ActiveSupport::TestCase
   end
 
   def test_unknown_zones_dont_store_mapping_keys
-    ActiveSupport::TimeZone["bogus"]
-    assert !ActiveSupport::TimeZone.zones_map.key?("bogus")
+    assert_nil ActiveSupport::TimeZone["bogus"]
   end
 
   def test_new
@@ -414,4 +490,13 @@ class TimeZoneTest < ActiveSupport::TestCase
     assert ActiveSupport::TimeZone.us_zones.include?(ActiveSupport::TimeZone["Hawaii"])
     assert !ActiveSupport::TimeZone.us_zones.include?(ActiveSupport::TimeZone["Kuala Lumpur"])
   end
+
+  def test_to_yaml
+    assert_equal("--- !ruby/object:ActiveSupport::TimeZone\nname: Pacific/Honolulu\n", ActiveSupport::TimeZone["Hawaii"].to_yaml)
+    assert_equal("--- !ruby/object:ActiveSupport::TimeZone\nname: Europe/London\n", ActiveSupport::TimeZone["Europe/London"].to_yaml)
+  end
+
+  def test_yaml_load
+    assert_equal(ActiveSupport::TimeZone["Pacific/Honolulu"], YAML.load("--- !ruby/object:ActiveSupport::TimeZone\nname: Pacific/Honolulu\n"))
+  end
 end
diff --git a/activesupport/test/transliterate_test.rb b/activesupport/test/transliterate_test.rb
index 6833ae68a7..378421fedd 100644
--- a/activesupport/test/transliterate_test.rb
+++ b/activesupport/test/transliterate_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'active_support/inflector/transliterate'
 
diff --git a/activesupport/test/xml_mini_test.rb b/activesupport/test/xml_mini_test.rb
index f49431cbbf..55e8181b54 100644
--- a/activesupport/test/xml_mini_test.rb
+++ b/activesupport/test/xml_mini_test.rb
@@ -1,9 +1,9 @@
 require 'abstract_unit'
 require 'active_support/xml_mini'
 require 'active_support/builder'
-require 'active_support/core_ext/array'
 require 'active_support/core_ext/hash'
 require 'active_support/core_ext/big_decimal'
+require 'yaml'
 
 module XmlMiniTest
   class RenameKeyTest < ActiveSupport::TestCase
@@ -11,7 +11,7 @@ module XmlMiniTest
       assert_equal "my-key", ActiveSupport::XmlMini.rename_key("my_key")
     end
 
-    def test_rename_key_does_nothing_with_dasherize_true
+    def test_rename_key_dasherizes_with_dasherize_true
       assert_equal "my-key", ActiveSupport::XmlMini.rename_key("my_key", :dasherize => true)
     end
 
diff --git a/ci/travis.rb b/ci/travis.rb
index b62f90a59e..52fef05fbf 100755
--- a/ci/travis.rb
+++ b/ci/travis.rb
@@ -16,13 +16,14 @@ end
 class Build
   MAP = {
     'railties' => 'railties',
-    'ap'   => 'actionpack',
-    'am'   => 'actionmailer',
-    'amo'  => 'activemodel',
-    'as'   => 'activesupport',
-    'ar'   => 'activerecord',
-    'av'   => 'actionview',
-    'aj'   => 'activejob'
+    'ap'       => 'actionpack',
+    'am'       => 'actionmailer',
+    'amo'      => 'activemodel',
+    'as'       => 'activesupport',
+    'ar'       => 'activerecord',
+    'av'       => 'actionview',
+    'aj'       => 'activejob',
+    'guides'   => 'guides'
   }
 
   attr_reader :component, :options
@@ -36,7 +37,11 @@ class Build
     self.options.update(options)
     Dir.chdir(dir) do
       announce(heading)
-      rake(*tasks)
+      if guides?
+        run_bug_report_templates
+      else
+        rake(*tasks)
+      end
     end
   end
 
@@ -71,6 +76,10 @@ class Build
     gem == 'activerecord'
   end
 
+  def guides?
+    gem == 'guides'
+  end
+
   def isolated?
     options[:isolated]
   end
@@ -96,6 +105,12 @@ class Build
     end
     true
   end
+
+  def run_bug_report_templates
+    Dir.glob('bug_report_templates/*.rb').all? do |file|
+      system(Gem.ruby, '-w', file)
+    end
+  end
 end
 
 if ENV['GEM']=='aj:integration'
@@ -110,6 +125,7 @@ ENV['GEM'].split(',').each do |gem|
     next if ENV['TRAVIS_PULL_REQUEST'] && ENV['TRAVIS_PULL_REQUEST'] != 'false' && isolated
     next if gem == 'railties' && isolated
     next if gem == 'aj:integration' && isolated
+    next if gem == 'guides' && isolated
 
     build = Build.new(gem, :isolated => isolated)
     results[build.key] = build.run!
diff --git a/guides/CHANGELOG.md b/guides/CHANGELOG.md
index cd3fa9f65b..09fb7b1a0e 100644
--- a/guides/CHANGELOG.md
+++ b/guides/CHANGELOG.md
@@ -1,5 +1,21 @@
+*   Add code of conduct to contributing guide
+
+    *Jon Moss*
+
+*   New section in Configuring: Configuring Active Job
+
+    *Eliot Sykes*
+
+*   New section in Active Record Association Basics: Single Table Inheritance
+
+    *Andrey Nering*
+
 *   New section in Active Record Querying: Understanding The Method Chaining
 
     *Andrey Nering*
 
+*   New section in Configuring: Search Engines Indexing
+
+    *Andrey Nering*
+
 Please check [4-2-stable](https://github.com/rails/rails/blob/4-2-stable/guides/CHANGELOG.md) for previous changes.
diff --git a/guides/Rakefile b/guides/Rakefile
index fd093b94c1..00577377d7 100644
--- a/guides/Rakefile
+++ b/guides/Rakefile
@@ -7,11 +7,11 @@ namespace :guides do
 
     desc "Generate HTML guides"
     task :html do
-      ENV["WARN_BROKEN_LINKS"] = "1" # authors can't disable this
+      ENV["WARNINGS"] = "1" # authors can't disable this
       ruby "rails_guides.rb"
     end
 
-    desc "Generate .mobi file. The kindlegen executable must be in your PATH. You can get it for free from http://www.amazon.com/kindlepublishing"
+    desc "Generate .mobi file. The kindlegen executable must be in your PATH. You can get it for free from http://www.amazon.com/gp/feature.html?docId=1000765211"
     task :kindle do
       unless `kindlerb -v 2> /dev/null` =~ /kindlerb 0.1.1/
         abort "Please `gem install kindlerb` and make sure you have `kindlegen` in your PATH"
diff --git a/guides/assets/images/favicon.ico b/guides/assets/images/favicon.ico
index e0e80cf8f1..faa10b4580 100644
--- a/guides/assets/images/favicon.ico
+++ b/guides/assets/images/favicon.ico
diff --git a/guides/assets/images/getting_started/article_with_comments.png b/guides/assets/images/getting_started/article_with_comments.png
index 117a78a39f..c489e4c00e 100644
--- a/guides/assets/images/getting_started/article_with_comments.png
+++ b/guides/assets/images/getting_started/article_with_comments.png
diff --git a/guides/assets/images/getting_started/rails_welcome.png b/guides/assets/images/getting_started/rails_welcome.png
index 3e07c948a0..4d0cb417b7 100644
--- a/guides/assets/images/getting_started/rails_welcome.png
+++ b/guides/assets/images/getting_started/rails_welcome.png
diff --git a/guides/bug_report_templates/action_controller_gem.rb b/guides/bug_report_templates/action_controller_gem.rb
index e04d79c818..58ba708a39 100644
--- a/guides/bug_report_templates/action_controller_gem.rb
+++ b/guides/bug_report_templates/action_controller_gem.rb
@@ -1,7 +1,17 @@
-# Activate the gem you are reporting the issue against.
-gem 'rails', '4.2.0'
+begin
+  require 'bundler/inline'
+rescue LoadError => e
+  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
+  raise e
+end
+
+gemfile(true) do
+  source 'https://rubygems.org'
+  # Activate the gem you are reporting the issue against.
+  gem 'rails', '4.2.0'
+end
 
-require 'rails'
+require 'rack/test'
 require 'action_controller/railtie'
 
 class TestApp < Rails::Application
@@ -22,12 +32,11 @@ class TestController < ActionController::Base
   include Rails.application.routes.url_helpers
 
   def index
-    render text: 'Home'
+    render plain: 'Home'
   end
 end
 
 require 'minitest/autorun'
-require 'rack/test'
 
 # Ensure backward compatibility with Minitest 4
 Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)
diff --git a/guides/bug_report_templates/action_controller_master.rb b/guides/bug_report_templates/action_controller_master.rb
index 9be8130884..3f24aa3b4d 100644
--- a/guides/bug_report_templates/action_controller_master.rb
+++ b/guides/bug_report_templates/action_controller_master.rb
@@ -1,17 +1,20 @@
-unless File.exist?('Gemfile')
-  File.write('Gemfile', <<-GEMFILE)
-    source 'https://rubygems.org'
-    gem 'rails', github: 'rails/rails'
-    gem 'arel', github: 'rails/arel'
-  GEMFILE
-
-  system 'bundle'
+begin
+  require 'bundler/inline'
+rescue LoadError => e
+  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
+  raise e
 end
 
-require 'bundler'
-Bundler.setup(:default)
+gemfile(true) do
+  source 'https://rubygems.org'
+  gem 'rails', github: 'rails/rails'
+  gem 'arel', github: 'rails/arel'
+  gem 'rack', github: 'rack/rack'
+  gem 'sprockets', github: 'rails/sprockets'
+  gem 'sprockets-rails', github: 'rails/sprockets-rails'
+  gem 'sass-rails', github: 'rails/sass-rails'
+end
 
-require 'rails'
 require 'action_controller/railtie'
 
 class TestApp < Rails::Application
@@ -32,7 +35,7 @@ class TestController < ActionController::Base
   include Rails.application.routes.url_helpers
 
   def index
-    render text: 'Home'
+    render plain: 'Home'
   end
 end
 
diff --git a/guides/bug_report_templates/active_record_gem.rb b/guides/bug_report_templates/active_record_gem.rb
index 66bbb15afb..09d6e7b331 100644
--- a/guides/bug_report_templates/active_record_gem.rb
+++ b/guides/bug_report_templates/active_record_gem.rb
@@ -1,5 +1,17 @@
-# Activate the gem you are reporting the issue against.
-gem 'activerecord', '4.2.0'
+begin
+  require 'bundler/inline'
+rescue LoadError => e
+  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
+  raise e
+end
+
+gemfile(true) do
+  source 'https://rubygems.org'
+  # Activate the gem you are reporting the issue against.
+  gem 'activerecord', '4.2.0'
+  gem 'sqlite3'
+end
+
 require 'active_record'
 require 'minitest/autorun'
 require 'logger'
@@ -12,10 +24,10 @@ ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:'
 ActiveRecord::Base.logger = Logger.new(STDOUT)
 
 ActiveRecord::Schema.define do
-  create_table :posts do |t|
+  create_table :posts, force: true do |t|
   end
 
-  create_table :comments do |t|
+  create_table :comments, force: true do |t|
     t.integer :post_id
   end
 end
diff --git a/guides/bug_report_templates/active_record_master.rb b/guides/bug_report_templates/active_record_master.rb
index d95354e12d..5b742a9093 100644
--- a/guides/bug_report_templates/active_record_master.rb
+++ b/guides/bug_report_templates/active_record_master.rb
@@ -1,16 +1,20 @@
-unless File.exist?('Gemfile')
-  File.write('Gemfile', <<-GEMFILE)
-    source 'https://rubygems.org'
-    gem 'rails', github: 'rails/rails'
-    gem 'arel', github: 'rails/arel'
-    gem 'sqlite3'
-  GEMFILE
-
-  system 'bundle'
+begin
+  require 'bundler/inline'
+rescue LoadError => e
+  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
+  raise e
 end
 
-require 'bundler'
-Bundler.setup(:default)
+gemfile(true) do
+  source 'https://rubygems.org'
+  gem 'rails', github: 'rails/rails'
+  gem 'arel', github: 'rails/arel'
+  gem 'rack', github: 'rack/rack'
+  gem 'sprockets', github: 'rails/sprockets'
+  gem 'sprockets-rails', github: 'rails/sprockets-rails'
+  gem 'sass-rails', github: 'rails/sass-rails'
+  gem 'sqlite3'
+end
 
 require 'active_record'
 require 'minitest/autorun'
@@ -21,10 +25,10 @@ ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:'
 ActiveRecord::Base.logger = Logger.new(STDOUT)
 
 ActiveRecord::Schema.define do
-  create_table :posts do |t|
+  create_table :posts, force: true  do |t|
   end
 
-  create_table :comments do |t|
+  create_table :comments, force: true  do |t|
     t.integer :post_id
   end
 end
diff --git a/guides/bug_report_templates/generic_gem.rb b/guides/bug_report_templates/generic_gem.rb
new file mode 100644
index 0000000000..a4fe51156d
--- /dev/null
+++ b/guides/bug_report_templates/generic_gem.rb
@@ -0,0 +1,25 @@
+begin
+  require 'bundler/inline'
+rescue LoadError => e
+  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
+  raise e
+end
+
+gemfile(true) do
+  source 'https://rubygems.org'
+  # Activate the gem you are reporting the issue against.
+  gem 'activesupport', '4.2.0'
+end
+
+require 'active_support/core_ext/object/blank'
+require 'minitest/autorun'
+
+# Ensure backward compatibility with Minitest 4
+Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)
+
+class BugTest < Minitest::Test
+  def test_stuff
+    assert "zomg".present?
+    refute "".present?
+  end
+end
diff --git a/guides/bug_report_templates/generic_master.rb b/guides/bug_report_templates/generic_master.rb
new file mode 100644
index 0000000000..0a8048cc48
--- /dev/null
+++ b/guides/bug_report_templates/generic_master.rb
@@ -0,0 +1,30 @@
+begin
+  require 'bundler/inline'
+rescue LoadError => e
+  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
+  raise e
+end
+
+gemfile(true) do
+  source 'https://rubygems.org'
+  gem 'rails', github: 'rails/rails'
+  gem 'arel', github: 'rails/arel'
+  gem 'rack', github: 'rack/rack'
+  gem 'sprockets', github: 'rails/sprockets'
+  gem 'sprockets-rails', github: 'rails/sprockets-rails'
+  gem 'sass-rails', github: 'rails/sass-rails'
+end
+
+require 'active_support'
+require 'active_support/core_ext/object/blank'
+require 'minitest/autorun'
+
+# Ensure backward compatibility with Minitest 4
+Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)
+
+class BugTest < Minitest::Test
+  def test_stuff
+    assert "zomg".present?
+    refute "".present?
+  end
+end
diff --git a/guides/rails_guides.rb b/guides/rails_guides.rb
index 762ab1c0e2..367ed0b12e 100644
--- a/guides/rails_guides.rb
+++ b/guides/rails_guides.rb
@@ -1,13 +1,6 @@
 pwd = File.dirname(__FILE__)
 $:.unshift pwd
 
-# This is a predicate useful for the doc:guides task of applications.
-def bundler?
-  # Note that rake sets the cwd to the one that contains the Rakefile
-  # being executed.
-  File.exist?('Gemfile')
-end
-
 begin
   # Guides generation in the Rails repo.
   as_lib = File.join(pwd, "../activesupport/lib")
@@ -20,44 +13,5 @@ rescue LoadError
   gem "actionpack", '>= 3.0'
 end
 
-begin
-  require 'redcarpet'
-rescue LoadError
-  # This can happen if doc:guides is executed in an application.
-  $stderr.puts('Generating guides requires Redcarpet 3.2.2+.')
-  $stderr.puts(<<ERROR) if bundler?
-Please add
-
-  gem 'redcarpet', '~> 3.2.2'
-
-to the Gemfile, run
-
-  bundle install
-
-and try again.
-ERROR
-  exit 1
-end
-
-begin
-  require 'nokogiri'
-rescue LoadError
-  # This can happen if doc:guides is executed in an application.
-  $stderr.puts('Generating guides requires Nokogiri.')
-  $stderr.puts(<<ERROR) if bundler?
-Please add
-
-  gem 'nokogiri'
-
-to the Gemfile, run
-
-  bundle install
-
-and try again.
-ERROR
-  exit 1
-end
-
-require 'rails_guides/markdown'
 require "rails_guides/generator"
 RailsGuides::Generator.new.generate
diff --git a/guides/rails_guides/generator.rb b/guides/rails_guides/generator.rb
index aa900454c8..b7a94f144c 100644
--- a/guides/rails_guides/generator.rb
+++ b/guides/rails_guides/generator.rb
@@ -57,6 +57,7 @@ require 'active_support/core_ext/object/blank'
 require 'action_controller'
 require 'action_view'
 
+require 'rails_guides/markdown'
 require 'rails_guides/indexer'
 require 'rails_guides/helpers'
 require 'rails_guides/levenshtein'
@@ -193,7 +194,7 @@ module RailsGuides
       layout = kindle? ? 'kindle/layout' : 'layout'
 
       File.open(output_path, 'w') do |f|
-        view = ActionView::Base.new(source_dir, :edge => @edge, :version => @version, :mobi => "kindle/#{mobi}")
+        view = ActionView::Base.new(source_dir, :edge => @edge, :version => @version, :mobi => "kindle/#{mobi}", :lang => @lang)
         view.extend(Helpers)
 
         if guide =~ /\.(\w+)\.erb$/
diff --git a/guides/rails_guides/helpers.rb b/guides/rails_guides/helpers.rb
index a78c2e9fca..5bf73da16c 100644
--- a/guides/rails_guides/helpers.rb
+++ b/guides/rails_guides/helpers.rb
@@ -15,7 +15,7 @@ module RailsGuides
     end
 
     def documents_by_section
-      @documents_by_section ||= YAML.load_file(File.expand_path('../../source/documents.yaml', __FILE__))
+      @documents_by_section ||= YAML.load_file(File.expand_path("../../source/#{@lang ? @lang + '/' : ''}documents.yaml", __FILE__))
     end
 
     def documents_flat
diff --git a/guides/rails_guides/levenshtein.rb b/guides/rails_guides/levenshtein.rb
index 8a908a4339..049f633258 100644
--- a/guides/rails_guides/levenshtein.rb
+++ b/guides/rails_guides/levenshtein.rb
@@ -7,19 +7,20 @@ module RailsGuides
       t = str2
       n = s.length
       m = t.length
-      max = n/2
 
       return m if (0 == n)
       return n if (0 == m)
-      return n if (n - m).abs > max
 
       d = (0..m).to_a
       x = nil
 
-      str1.each_char.each_with_index do |char1,i|
+      # avoid duplicating an enumerable object in the loop
+      str2_codepoint_enumerable = str2.each_codepoint
+
+      str1.each_codepoint.with_index do |char1, i|
         e = i+1
 
-        str2.each_char.each_with_index do |char2,j|
+        str2_codepoint_enumerable.with_index do |char2, j|
           cost = (char1 == char2) ? 0 : 1
           x = [
                d[j+1] + 1, # insertion
diff --git a/guides/rails_guides/markdown.rb b/guides/rails_guides/markdown.rb
index 17035069d0..69c7cd5136 100644
--- a/guides/rails_guides/markdown.rb
+++ b/guides/rails_guides/markdown.rb
@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 require 'redcarpet'
 require 'nokogiri'
 require 'rails_guides/markdown/renderer'
diff --git a/guides/source/2_3_release_notes.md b/guides/source/2_3_release_notes.md
index 328656f4a4..0a62f34371 100644
--- a/guides/source/2_3_release_notes.md
+++ b/guides/source/2_3_release_notes.md
@@ -187,7 +187,7 @@ MySQL supports a reconnect flag in its connections - if set to true, then the cl
 
 * Lead Contributor: [Dov Murik](http://twitter.com/dubek)
 * More information:
-    * [Controlling Automatic Reconnection Behavior](http://dev.mysql.com/doc/refman/5.0/en/auto-reconnect.html)
+    * [Controlling Automatic Reconnection Behavior](http://dev.mysql.com/doc/refman/5.6/en/auto-reconnect.html)
     * [MySQL auto-reconnect revisited](http://groups.google.com/group/rubyonrails-core/browse_thread/thread/49d2a7e9c96cb9f4)
 
 ### Other Active Record Changes
diff --git a/guides/source/3_0_release_notes.md b/guides/source/3_0_release_notes.md
index 9ad32e8168..696493a3cf 100644
--- a/guides/source/3_0_release_notes.md
+++ b/guides/source/3_0_release_notes.md
@@ -88,7 +88,7 @@ $ cd myapp
 
 Rails now uses a `Gemfile` in the application root to determine the gems you require for your application to start. This `Gemfile` is processed by the [Bundler](http://github.com/carlhuda/bundler,) which then installs all your dependencies. It can even install all the dependencies locally to your application so that it doesn't depend on the system gems.
 
-More information: - [bundler homepage](http://gembundler.com)
+More information: - [bundler homepage](http://bundler.io/)
 
 ### Living on the Edge
 
diff --git a/guides/source/3_1_release_notes.md b/guides/source/3_1_release_notes.md
index e187e5f9ab..327495704a 100644
--- a/guides/source/3_1_release_notes.md
+++ b/guides/source/3_1_release_notes.md
@@ -151,7 +151,7 @@ $ cd myapp
 
 Rails now uses a `Gemfile` in the application root to determine the gems you require for your application to start. This `Gemfile` is processed by the [Bundler](https://github.com/carlhuda/bundler) gem, which then installs all your dependencies. It can even install all the dependencies locally to your application so that it doesn't depend on the system gems.
 
-More information: - [bundler homepage](http://gembundler.com)
+More information: - [bundler homepage](http://bundler.io/)
 
 ### Living on the Edge
 
@@ -174,7 +174,7 @@ Rails Architectural Changes
 
 The major change in Rails 3.1 is the Assets Pipeline. It makes CSS and JavaScript first-class code citizens and enables proper organization, including use in plugins and engines.
 
-The assets pipeline is powered by [Sprockets](https://github.com/sstephenson/sprockets) and is covered in the [Asset Pipeline](asset_pipeline.html) guide.
+The assets pipeline is powered by [Sprockets](https://github.com/rails/sprockets) and is covered in the [Asset Pipeline](asset_pipeline.html) guide.
 
 ### HTTP Streaming
 
@@ -199,7 +199,7 @@ Railties
 
 * jQuery is the new default JavaScript library.
 
-* jQuery and Prototype are no longer vendored and is provided from now on by the jquery-rails and prototype-rails gems.
+* jQuery and Prototype are no longer vendored and is provided from now on by the `jquery-rails` and `prototype-rails` gems.
 
 * The application generator accepts an option `-j` which can be an arbitrary string. If passed "foo", the gem "foo-rails" is added to the `Gemfile`, and the application JavaScript manifest requires "foo" and "foo_ujs". Currently only "prototype-rails" and "jquery-rails" exist and provide those files via the asset pipeline.
 
diff --git a/guides/source/3_2_release_notes.md b/guides/source/3_2_release_notes.md
index 6ddf77d9c0..f6871c186e 100644
--- a/guides/source/3_2_release_notes.md
+++ b/guides/source/3_2_release_notes.md
@@ -81,7 +81,7 @@ $ cd myapp
 
 Rails now uses a `Gemfile` in the application root to determine the gems you require for your application to start. This `Gemfile` is processed by the [Bundler](https://github.com/carlhuda/bundler) gem, which then installs all your dependencies. It can even install all the dependencies locally to your application so that it doesn't depend on the system gems.
 
-More information: [Bundler homepage](http://gembundler.com)
+More information: [Bundler homepage](http://bundler.io/)
 
 ### Living on the Edge
 
@@ -327,7 +327,7 @@ Active Record
 
 * Implemented `ActiveRecord::Relation#explain`.
 
-* Implements `AR::Base.silence_auto_explain` which allows the user to selectively disable automatic EXPLAINs within a block.
+* Implements `ActiveRecord::Base.silence_auto_explain` which allows the user to selectively disable automatic EXPLAINs within a block.
 
 * Implements automatic EXPLAIN logging for slow queries. A new configuration parameter `config.active_record.auto_explain_threshold_in_seconds` determines what's to be considered a slow query. Setting that to nil disables this feature. Defaults are 0.5 in development mode, and nil in test and production modes. Rails 3.2 supports this feature in SQLite, MySQL (mysql2 adapter), and PostgreSQL.
 
diff --git a/guides/source/4_0_release_notes.md b/guides/source/4_0_release_notes.md
index 67f4a3c02c..b9444510ea 100644
--- a/guides/source/4_0_release_notes.md
+++ b/guides/source/4_0_release_notes.md
@@ -36,7 +36,7 @@ $ cd myapp
 
 Rails now uses a `Gemfile` in the application root to determine the gems you require for your application to start. This `Gemfile` is processed by the [Bundler](https://github.com/carlhuda/bundler) gem, which then installs all your dependencies. It can even install all the dependencies locally to your application so that it doesn't depend on the system gems.
 
-More information: [Bundler homepage](http://gembundler.com)
+More information: [Bundler homepage](http://bundler.io)
 
 ### Living on the Edge
 
@@ -59,25 +59,25 @@ Major Features
 
 ### Upgrade
 
- * **Ruby 1.9.3** ([commit](https://github.com/rails/rails/commit/a0380e808d3dbd2462df17f5d3b7fcd8bd812496)) - Ruby 2.0 preferred; 1.9.3+ required
- * **[New deprecation policy](http://www.youtube.com/watch?v=z6YgD6tVPQs)** - Deprecated features are warnings in Rails 4.0 and will be removed in Rails 4.1.
- * **ActionPack page and action caching** ([commit](https://github.com/rails/rails/commit/b0a7068564f0c95e7ef28fc39d0335ed17d93e90)) - Page and action caching are extracted to a separate gem. Page and action caching requires too much manual intervention (manually expiring caches when the underlying model objects are updated). Instead, use Russian doll caching.
- * **ActiveRecord observers** ([commit](https://github.com/rails/rails/commit/ccecab3ba950a288b61a516bf9b6962e384aae0b)) - Observers are extracted to a separate gem. Observers are only needed for page and action caching, and can lead to spaghetti code.
- * **ActiveRecord session store** ([commit](https://github.com/rails/rails/commit/0ffe19056c8e8b2f9ae9d487b896cad2ce9387ad)) - The ActiveRecord session store is extracted to a separate gem. Storing sessions in SQL is costly. Instead, use cookie sessions, memcache sessions, or a custom session store.
- * **ActiveModel mass assignment protection** ([commit](https://github.com/rails/rails/commit/f8c9a4d3e88181cee644f91e1342bfe896ca64c6)) - Rails 3 mass assignment protection is deprecated. Instead, use strong parameters.
- * **ActiveResource** ([commit](https://github.com/rails/rails/commit/f1637bf2bb00490203503fbd943b73406e043d1d)) - ActiveResource is extracted to a separate gem. ActiveResource was not widely used.
- * **vendor/plugins removed** ([commit](https://github.com/rails/rails/commit/853de2bd9ac572735fa6cf59fcf827e485a231c3)) - Use a Gemfile to manage installed gems.
+* **Ruby 1.9.3** ([commit](https://github.com/rails/rails/commit/a0380e808d3dbd2462df17f5d3b7fcd8bd812496)) - Ruby 2.0 preferred; 1.9.3+ required
+* **[New deprecation policy](http://www.youtube.com/watch?v=z6YgD6tVPQs)** - Deprecated features are warnings in Rails 4.0 and will be removed in Rails 4.1.
+* **ActionPack page and action caching** ([commit](https://github.com/rails/rails/commit/b0a7068564f0c95e7ef28fc39d0335ed17d93e90)) - Page and action caching are extracted to a separate gem. Page and action caching requires too much manual intervention (manually expiring caches when the underlying model objects are updated). Instead, use Russian doll caching.
+* **ActiveRecord observers** ([commit](https://github.com/rails/rails/commit/ccecab3ba950a288b61a516bf9b6962e384aae0b)) - Observers are extracted to a separate gem. Observers are only needed for page and action caching, and can lead to spaghetti code.
+* **ActiveRecord session store** ([commit](https://github.com/rails/rails/commit/0ffe19056c8e8b2f9ae9d487b896cad2ce9387ad)) - The ActiveRecord session store is extracted to a separate gem. Storing sessions in SQL is costly. Instead, use cookie sessions, memcache sessions, or a custom session store.
+* **ActiveModel mass assignment protection** ([commit](https://github.com/rails/rails/commit/f8c9a4d3e88181cee644f91e1342bfe896ca64c6)) - Rails 3 mass assignment protection is deprecated. Instead, use strong parameters.
+* **ActiveResource** ([commit](https://github.com/rails/rails/commit/f1637bf2bb00490203503fbd943b73406e043d1d)) - ActiveResource is extracted to a separate gem. ActiveResource was not widely used.
+* **vendor/plugins removed** ([commit](https://github.com/rails/rails/commit/853de2bd9ac572735fa6cf59fcf827e485a231c3)) - Use a Gemfile to manage installed gems.
 
 ### ActionPack
 
- * **Strong parameters** ([commit](https://github.com/rails/rails/commit/a8f6d5c6450a7fe058348a7f10a908352bb6c7fc)) - Only allow whitelisted parameters to update model objects (`params.permit(:title, :text)`).
- * **Routing concerns** ([commit](https://github.com/rails/rails/commit/0dd24728a088fcb4ae616bb5d62734aca5276b1b)) - In the routing DSL, factor out common subroutes (`comments` from `/posts/1/comments` and `/videos/1/comments`).
- * **ActionController::Live** ([commit](https://github.com/rails/rails/commit/af0a9f9eefaee3a8120cfd8d05cbc431af376da3)) - Stream JSON with `response.stream`.
- * **Declarative ETags** ([commit](https://github.com/rails/rails/commit/ed5c938fa36995f06d4917d9543ba78ed506bb8d)) - Add controller-level etag additions that will be part of the action etag computation
- * **[Russian doll caching](http://37signals.com/svn/posts/3113-how-key-based-cache-expiration-works)** ([commit](https://github.com/rails/rails/commit/4154bf012d2bec2aae79e4a49aa94a70d3e91d49)) - Cache nested fragments of views. Each fragment expires based on a set of dependencies (a cache key). The cache key is usually a template version number and a model object.
- * **Turbolinks** ([commit](https://github.com/rails/rails/commit/e35d8b18d0649c0ecc58f6b73df6b3c8d0c6bb74)) - Serve only one initial HTML page. When the user navigates to another page, use pushState to update the URL and use AJAX to update the title and body.
- * **Decouple ActionView from ActionController** ([commit](https://github.com/rails/rails/commit/78b0934dd1bb84e8f093fb8ef95ca99b297b51cd)) - ActionView was decoupled from ActionPack and will be moved to a separated gem in Rails 4.1.
- * **Do not depend on ActiveModel** ([commit](https://github.com/rails/rails/commit/166dbaa7526a96fdf046f093f25b0a134b277a68)) - ActionPack no longer depends on ActiveModel.
+* **Strong parameters** ([commit](https://github.com/rails/rails/commit/a8f6d5c6450a7fe058348a7f10a908352bb6c7fc)) - Only allow whitelisted parameters to update model objects (`params.permit(:title, :text)`).
+* **Routing concerns** ([commit](https://github.com/rails/rails/commit/0dd24728a088fcb4ae616bb5d62734aca5276b1b)) - In the routing DSL, factor out common subroutes (`comments` from `/posts/1/comments` and `/videos/1/comments`).
+* **ActionController::Live** ([commit](https://github.com/rails/rails/commit/af0a9f9eefaee3a8120cfd8d05cbc431af376da3)) - Stream JSON with `response.stream`.
+* **Declarative ETags** ([commit](https://github.com/rails/rails/commit/ed5c938fa36995f06d4917d9543ba78ed506bb8d)) - Add controller-level etag additions that will be part of the action etag computation.
+* **[Russian doll caching](http://37signals.com/svn/posts/3113-how-key-based-cache-expiration-works)** ([commit](https://github.com/rails/rails/commit/4154bf012d2bec2aae79e4a49aa94a70d3e91d49)) - Cache nested fragments of views. Each fragment expires based on a set of dependencies (a cache key). The cache key is usually a template version number and a model object.
+* **Turbolinks** ([commit](https://github.com/rails/rails/commit/e35d8b18d0649c0ecc58f6b73df6b3c8d0c6bb74)) - Serve only one initial HTML page. When the user navigates to another page, use pushState to update the URL and use AJAX to update the title and body.
+* **Decouple ActionView from ActionController** ([commit](https://github.com/rails/rails/commit/78b0934dd1bb84e8f093fb8ef95ca99b297b51cd)) - ActionView was decoupled from ActionPack and will be moved to a separated gem in Rails 4.1.
+* **Do not depend on ActiveModel** ([commit](https://github.com/rails/rails/commit/166dbaa7526a96fdf046f093f25b0a134b277a68)) - ActionPack no longer depends on ActiveModel.
 
 ### General
 
@@ -87,14 +87,17 @@ Major Features
  * **Support for specifying transaction isolation level** ([commit](https://github.com/rails/rails/commit/392eeecc11a291e406db927a18b75f41b2658253)) - Choose whether repeatable reads or improved performance (less locking) is more important.
  * **Dalli** ([commit](https://github.com/rails/rails/commit/82663306f428a5bbc90c511458432afb26d2f238)) - Use Dalli memcache client for the memcache store.
  * **Notifications start &amp; finish** ([commit](https://github.com/rails/rails/commit/f08f8750a512f741acb004d0cebe210c5f949f28)) - Active Support instrumentation reports start and finish notifications to subscribers.
- * **Thread safe by default** ([commit](https://github.com/rails/rails/commit/5d416b907864d99af55ebaa400fff217e17570cd)) - Rails can run in threaded app servers without additional configuration. Note: Check that the gems you are using are threadsafe.
+ * **Thread safe by default** ([commit](https://github.com/rails/rails/commit/5d416b907864d99af55ebaa400fff217e17570cd)) - Rails can run in threaded app servers without additional configuration.
+
+NOTE: Check that the gems you are using are threadsafe.
+
  * **PATCH verb** ([commit](https://github.com/rails/rails/commit/eed9f2539e3ab5a68e798802f464b8e4e95e619e)) - In Rails, PATCH replaces PUT. PATCH is used for partial updates of resources.
 
 ### Security
 
- * **match do not catch all** ([commit](https://github.com/rails/rails/commit/90d2802b71a6e89aedfe40564a37bd35f777e541)) - In the routing DSL, match requires the HTTP verb or verbs to be specified.
- * **html entities escaped by default** ([commit](https://github.com/rails/rails/commit/5f189f41258b83d49012ec5a0678d827327e7543)) - Strings rendered in erb are escaped unless wrapped with `raw` or `html_safe` is called.
- * **New security headers** ([commit](https://github.com/rails/rails/commit/6794e92b204572d75a07bd6413bdae6ae22d5a82)) - Rails sends the following headers with every HTTP request: `X-Frame-Options` (prevents clickjacking by forbidding the browser from embedding the page in a frame), `X-XSS-Protection` (asks the browser to halt script injection) and `X-Content-Type-Options` (prevents the browser from opening a jpeg as an exe).
+* **match do not catch all** ([commit](https://github.com/rails/rails/commit/90d2802b71a6e89aedfe40564a37bd35f777e541)) - In the routing DSL, match requires the HTTP verb or verbs to be specified.
+* **html entities escaped by default** ([commit](https://github.com/rails/rails/commit/5f189f41258b83d49012ec5a0678d827327e7543)) - Strings rendered in erb are escaped unless wrapped with `raw` or `html_safe` is called.
+* **New security headers** ([commit](https://github.com/rails/rails/commit/6794e92b204572d75a07bd6413bdae6ae22d5a82)) - Rails sends the following headers with every HTTP request: `X-Frame-Options` (prevents clickjacking by forbidding the browser from embedding the page in a frame), `X-XSS-Protection` (asks the browser to halt script injection) and `X-Content-Type-Options` (prevents the browser from opening a jpeg as an exe).
 
 Extraction of features to gems
 ---------------------------
@@ -181,7 +184,7 @@ Please refer to the [Changelog](https://github.com/rails/rails/blob/4-0-stable/a
 * `String#to_date` now raises `ArgumentError: invalid date` instead of `NoMethodError: undefined method 'div' for nil:NilClass`
   when given an invalid date. It is now the same as `Date.parse`, and it accepts more invalid dates than 3.x, such as:
 
-  ```
+  ```ruby
   # ActiveSupport 3.x
   "asdf".to_date # => NoMethodError: undefined method `div' for nil:NilClass
   "333".to_date # => NoMethodError: undefined method `div' for nil:NilClass
diff --git a/guides/source/4_1_release_notes.md b/guides/source/4_1_release_notes.md
index 8d5557be6e..6bf65757ec 100644
--- a/guides/source/4_1_release_notes.md
+++ b/guides/source/4_1_release_notes.md
@@ -317,15 +317,15 @@ for detailed changes.
 
 * Removed deprecated constants from Action Controller:
 
-  | Removed                            | Successor                       |
-  |:-----------------------------------|:--------------------------------|
-  | ActionController::AbstractRequest  | ActionDispatch::Request         |
-  | ActionController::Request          | ActionDispatch::Request         |
-  | ActionController::AbstractResponse | ActionDispatch::Response        |
-  | ActionController::Response         | ActionDispatch::Response        |
-  | ActionController::Routing          | ActionDispatch::Routing         |
-  | ActionController::Integration      | ActionDispatch::Integration     |
-  | ActionController::IntegrationTest  | ActionDispatch::IntegrationTest |
+| Removed                            | Successor                       |
+|:-----------------------------------|:--------------------------------|
+| ActionController::AbstractRequest  | ActionDispatch::Request         |
+| ActionController::Request          | ActionDispatch::Request         |
+| ActionController::AbstractResponse | ActionDispatch::Response        |
+| ActionController::Response         | ActionDispatch::Response        |
+| ActionController::Routing          | ActionDispatch::Routing         |
+| ActionController::Integration      | ActionDispatch::Integration     |
+| ActionController::IntegrationTest  | ActionDispatch::IntegrationTest |
 
 ### Notable changes
 
diff --git a/guides/source/4_2_release_notes.md b/guides/source/4_2_release_notes.md
index 366d9d26b4..8a59007420 100644
--- a/guides/source/4_2_release_notes.md
+++ b/guides/source/4_2_release_notes.md
@@ -227,6 +227,17 @@ restore the old behavior.
 If you do this, be sure to configure your firewall properly such that only
 trusted machines on your network can access your development server.
 
+### Changed status option symbols for `render`
+
+Due to a [change in Rack](https://github.com/rack/rack/commit/be28c6a2ac152fe4adfbef71f3db9f4200df89e8), the symbols that the `render` method accepts for the `:status` option have changed:
+
+- 306: `:reserved` has been removed.
+- 413: `:request_entity_too_large` has been renamed to `:payload_too_large`.
+- 414: `:request_uri_too_long` has been renamed to `:uri_too_long`.
+- 416: `:requested_range_not_satisfiable` has been renamed to `:range_not_satisfiable`.
+
+Keep in mind that if calling `render` with an unknown symbol, the response status will default to 500.
+
 ### HTML Sanitizer
 
 The HTML sanitizer has been replaced with a new, more robust, implementation
@@ -257,7 +268,7 @@ application is using any of these spellings, you will need to update them:
 *   Values in attribute selectors may need to be quoted if they contain
     non-alphanumeric characters.
 
-    ```
+    ```ruby
     # before
     a[href=/]
     a[href$=/]
@@ -272,7 +283,7 @@ application is using any of these spellings, you will need to update them:
 
     For example:
 
-    ``` ruby
+    ```ruby
     # content: <div><i><p></i></div>
 
     # before:
@@ -290,7 +301,7 @@ application is using any of these spellings, you will need to update them:
     used to be raw (e.g. `AT&amp;T`), and now is evaluated
     (e.g. `AT&T`).
 
-    ``` ruby
+    ```ruby
     # content: <p>AT&amp;T</p>
 
     # before:
@@ -302,6 +313,30 @@ application is using any of these spellings, you will need to update them:
     assert_select('p', 'AT&amp;T')  # => false
     ```
 
+Furthermore substitutions have changed syntax.
+
+Now you have to use a `:match` CSS-like selector:
+
+```ruby
+assert_select ":match('id', ?)", 'comment_1'
+```
+
+Additionally Regexp substitutions look different when the assertion fails.
+Notice how `/hello/` here:
+
+```ruby
+assert_select(":match('id', ?)", /hello/)
+```
+
+becomes `"(?-mix:hello)"`:
+
+```
+Expected at least 1 element matching "div:match('id', "(?-mix:hello)")", found 0..
+Expected 0 to be >= 1.
+```
+
+See the [Rails Dom Testing](https://github.com/rails/rails-dom-testing/tree/8798b9349fb9540ad8cb9a0ce6cb88d1384a210b) documentation for more on `assert_select`.
+
 
 Railties
 --------
diff --git a/guides/source/_welcome.html.erb b/guides/source/_welcome.html.erb
index 67f5f1cdd5..f50bcddbe7 100644
--- a/guides/source/_welcome.html.erb
+++ b/guides/source/_welcome.html.erb
@@ -16,9 +16,9 @@
 <% end %>
 <p>
 The guides for earlier releases:
-<a href="http://guides.rubyonrails.org/v4.2.0/">Rails 4.2.0</a>,
-<a href="http://guides.rubyonrails.org/v4.1.8/">Rails 4.1.8</a>,
-<a href="http://guides.rubyonrails.org/v4.0.12/">Rails 4.0.12</a>,
-<a href="http://guides.rubyonrails.org/v3.2.21/">Rails 3.2.21</a> and
-<a href="http://guides.rubyonrails.org/v2.3.11/">Rails 2.3.11</a>.
+<a href="http://guides.rubyonrails.org/v4.2/">Rails 4.2</a>,
+<a href="http://guides.rubyonrails.org/v4.1/">Rails 4.1</a>,
+<a href="http://guides.rubyonrails.org/v4.0/">Rails 4.0</a>,
+<a href="http://guides.rubyonrails.org/v3.2/">Rails 3.2</a>, and
+<a href="http://guides.rubyonrails.org/v2.3/">Rails 2.3</a>.
 </p>
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index 80000baf66..7e43ba375a 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -9,7 +9,7 @@ After reading this guide, you will know:
 
 * How to follow the flow of a request through a controller.
 * How to restrict parameters passed to your controller.
-* Why and how to store data in the session or cookies.
+* How and why to store data in the session or cookies.
 * How to work with filters to execute code during request processing.
 * How to use Action Controller's built-in HTTP authentication.
 * How to stream data directly to the user's browser.
@@ -21,11 +21,11 @@ After reading this guide, you will know:
 What Does a Controller Do?
 --------------------------
 
-Action Controller is the C in MVC. After routing has determined which controller to use for a request, your controller is responsible for making sense of the request and producing the appropriate output. Luckily, Action Controller does most of the groundwork for you and uses smart conventions to make this as straightforward as possible.
+Action Controller is the C in MVC. After routing has determined which controller to use for a request, the controller is responsible for making sense of the request and producing the appropriate output. Luckily, Action Controller does most of the groundwork for you and uses smart conventions to make this as straightforward as possible.
 
 For most conventional [RESTful](http://en.wikipedia.org/wiki/Representational_state_transfer) applications, the controller will receive the request (this is invisible to you as the developer), fetch or save data from a model and use a view to create HTML output. If your controller needs to do things a little differently, that's not a problem, this is just the most common way for a controller to work.
 
-A controller can thus be thought of as a middle man between models and views. It makes the model data available to the view so it can display that data to the user, and it saves or updates data from the user to the model.
+A controller can thus be thought of as a middleman between models and views. It makes the model data available to the view so it can display that data to the user, and it saves or updates user data to the model.
 
 NOTE: For more details on the routing process, see [Rails Routing from the Outside In](routing.html).
 
@@ -34,7 +34,7 @@ Controller Naming Convention
 
 The naming convention of controllers in Rails favors pluralization of the last word in the controller's name, although it is not strictly required (e.g. `ApplicationController`). For example, `ClientsController` is preferable to `ClientController`, `SiteAdminsController` is preferable to `SiteAdminController` or `SitesAdminsController`, and so on.
 
-Following this convention will allow you to use the default route generators (e.g. `resources`, etc) without needing to qualify each `:path` or `:controller`, and keeps URL and path helpers' usage consistent throughout your application. See [Layouts & Rendering Guide](layouts_and_rendering.html) for more details.
+Following this convention will allow you to use the default route generators (e.g. `resources`, etc) without needing to qualify each `:path` or `:controller`, and will keep URL and path helpers' usage consistent throughout your application. See [Layouts & Rendering Guide](layouts_and_rendering.html) for more details.
 
 NOTE: The controller naming convention differs from the naming convention of models, which are expected to be named in singular form.
 
@@ -51,7 +51,7 @@ class ClientsController < ApplicationController
 end
 ```
 
-As an example, if a user goes to `/clients/new` in your application to add a new client, Rails will create an instance of `ClientsController` and run the `new` method. Note that the empty method from the example above would work just fine because Rails will by default render the `new.html.erb` view unless the action says otherwise. The `new` method could make available to the view a `@client` instance variable by creating a new `Client`:
+As an example, if a user goes to `/clients/new` in your application to add a new client, Rails will create an instance of `ClientsController` and call its `new` method. Note that the empty method from the example above would work just fine because Rails will by default render the `new.html.erb` view unless the action says otherwise. The `new` method could make available to the view a `@client` instance variable by creating a new `Client`:
 
 ```ruby
 def new
@@ -63,7 +63,7 @@ The [Layouts & Rendering Guide](layouts_and_rendering.html) explains this in mor
 
 `ApplicationController` inherits from `ActionController::Base`, which defines a number of helpful methods. This guide will cover some of these, but if you're curious to see what's in there, you can see all of them in the API documentation or in the source itself.
 
-Only public methods are callable as actions. It is a best practice to lower the visibility of methods which are not intended to be actions, like auxiliary methods or filters.
+Only public methods are callable as actions. It is a best practice to lower the visibility of methods (with `private` or `protected`) which are not intended to be actions, like auxiliary methods or filters.
 
 Parameters
 ----------
@@ -104,13 +104,13 @@ end
 
 ### Hash and Array Parameters
 
-The `params` hash is not limited to one-dimensional keys and values. It can contain arrays and (nested) hashes. To send an array of values, append an empty pair of square brackets "[]" to the key name:
+The `params` hash is not limited to one-dimensional keys and values. It can contain nested arrays and hashes. To send an array of values, append an empty pair of square brackets "[]" to the key name:
 
 ```
 GET /clients?ids[]=1&ids[]=2&ids[]=3
 ```
 
-NOTE: The actual URL in this example will be encoded as "/clients?ids%5b%5d=1&ids%5b%5d=2&ids%5b%5d=3" as "[" and "]" are not allowed in URLs. Most of the time you don't have to worry about this because the browser will take care of it for you, and Rails will decode it back when it receives it, but if you ever find yourself having to send those requests to the server manually you have to keep this in mind.
+NOTE: The actual URL in this example will be encoded as "/clients?ids%5b%5d=1&ids%5b%5d=2&ids%5b%5d=3" as the "[" and "]" characters are not allowed in URLs. Most of the time you don't have to worry about this because the browser will encode it for you, and Rails will decode it automatically, but if you ever find yourself having to send those requests to the server manually you should keep this in mind.
 
 The value of `params[:ids]` will now be `["1", "2", "3"]`. Note that parameter values are always strings; Rails makes no attempt to guess or cast the type.
 
@@ -118,7 +118,7 @@ NOTE: Values such as `[nil]` or `[nil, nil, ...]` in `params` are replaced
 with `[]` for security reasons by default. See [Security Guide](security.html#unsafe-query-generation)
 for more information.
 
-To send a hash you include the key name inside the brackets:
+To send a hash, you include the key name inside the brackets:
 
 ```html
 <form accept-charset="UTF-8" action="/clients" method="post">
@@ -131,11 +131,11 @@ To send a hash you include the key name inside the brackets:
 
 When this form is submitted, the value of `params[:client]` will be `{ "name" => "Acme", "phone" => "12345", "address" => { "postcode" => "12345", "city" => "Carrot City" } }`. Note the nested hash in `params[:client][:address]`.
 
-Note that the `params` hash is actually an instance of `ActiveSupport::HashWithIndifferentAccess`, which acts like a hash but lets you use symbols and strings interchangeably as keys.
+The `params` object acts like a Hash, but lets you use symbols and strings interchangeably as keys.
 
 ### JSON parameters
 
-If you're writing a web service application, you might find yourself more comfortable accepting parameters in JSON format. If the "Content-Type" header of your request is set to "application/json", Rails will automatically convert your parameters into the `params` hash, which you can access as you would normally.
+If you're writing a web service application, you might find yourself more comfortable accepting parameters in JSON format. If the "Content-Type" header of your request is set to "application/json", Rails will automatically load your parameters into the `params` hash, which you can access as you would normally.
 
 So for example, if you are sending this JSON content:
 
@@ -143,15 +143,15 @@ So for example, if you are sending this JSON content:
 { "company": { "name": "acme", "address": "123 Carrot Street" } }
 ```
 
-You'll get `params[:company]` as `{ "name" => "acme", "address" => "123 Carrot Street" }`.
+Your controller will receive `params[:company]` as `{ "name" => "acme", "address" => "123 Carrot Street" }`.
 
-Also, if you've turned on `config.wrap_parameters` in your initializer or calling `wrap_parameters` in your controller, you can safely omit the root element in the JSON parameter. The parameters will be cloned and wrapped in the key according to your controller's name by default. So the above parameter can be written as:
+Also, if you've turned on `config.wrap_parameters` in your initializer or called `wrap_parameters` in your controller, you can safely omit the root element in the JSON parameter. In this case, the parameters will be cloned and wrapped with a key chosen based on your controller's name. So the above JSON POST can be written as:
 
 ```json
 { "name": "acme", "address": "123 Carrot Street" }
 ```
 
-And assume that you're sending the data to `CompaniesController`, it would then be wrapped in `:company` key like this:
+And, assuming that you're sending the data to `CompaniesController`, it would then be wrapped within the `:company` key like this:
 
 ```ruby
 { name: "acme", address: "123 Carrot Street", company: { name: "acme", address: "123 Carrot Street" } }
@@ -159,17 +159,17 @@ And assume that you're sending the data to `CompaniesController`, it would then
 
 You can customize the name of the key or specific parameters you want to wrap by consulting the [API documentation](http://api.rubyonrails.org/classes/ActionController/ParamsWrapper.html)
 
-NOTE: Support for parsing XML parameters has been extracted into a gem named `actionpack-xml_parser`
+NOTE: Support for parsing XML parameters has been extracted into a gem named `actionpack-xml_parser`.
 
 ### Routing Parameters
 
-The `params` hash will always contain the `:controller` and `:action` keys, but you should use the methods `controller_name` and `action_name` instead to access these values. Any other parameters defined by the routing, such as `:id` will also be available. As an example, consider a listing of clients where the list can show either active or inactive clients. We can add a route which captures the `:status` parameter in a "pretty" URL:
+The `params` hash will always contain the `:controller` and `:action` keys, but you should use the methods `controller_name` and `action_name` instead to access these values. Any other parameters defined by the routing, such as `:id`, will also be available. As an example, consider a listing of clients where the list can show either active or inactive clients. We can add a route which captures the `:status` parameter in a "pretty" URL:
 
 ```ruby
 get '/clients/:status' => 'clients#index', foo: 'bar'
 ```
 
-In this case, when a user opens the URL `/clients/active`, `params[:status]` will be set to "active". When this route is used, `params[:foo]` will also be set to "bar" just like it was passed in the query string. In the same way `params[:action]` will contain "index".
+In this case, when a user opens the URL `/clients/active`, `params[:status]` will be set to "active". When this route is used, `params[:foo]` will also be set to "bar", as if it were passed in the query string. Your controller will also receive `params[:action]` as "index" and `params[:controller]` as "clients".
 
 ### `default_url_options`
 
@@ -183,21 +183,23 @@ class ApplicationController < ActionController::Base
 end
 ```
 
-These options will be used as a starting point when generating URLs, so it's possible they'll be overridden by the options passed in `url_for` calls.
+These options will be used as a starting point when generating URLs, so it's possible they'll be overridden by the options passed to `url_for` calls.
 
-If you define `default_url_options` in `ApplicationController`, as in the example above, it would be used for all URL generation. The method can also be defined in one specific controller, in which case it only affects URLs generated there.
+If you define `default_url_options` in `ApplicationController`, as in the example above, these defaults will be used for all URL generation. The method can also be defined in a specific controller, in which case it only affects URLs generated there.
+
+In a given request, the method is not actually called for every single generated URL; for performance reasons, the returned hash is cached, there is at most one invocation per request.
 
 ### Strong Parameters
 
 With strong parameters, Action Controller parameters are forbidden to
 be used in Active Model mass assignments until they have been
-whitelisted. This means you'll have to make a conscious choice about
-which attributes to allow for mass updating and thus prevent
-accidentally exposing that which shouldn't be exposed.
+whitelisted. This means that you'll have to make a conscious decision about
+which attributes to allow for mass update. This is a better security
+practice to help prevent accidentally allowing users to update sensitive
+model attributes.
 
-In addition, parameters can be marked as required and flow through a
-predefined raise/rescue flow to end up as a 400 Bad Request with no
-effort.
+In addition, parameters can be marked as required and will flow through a
+predefined raise/rescue flow to end up as a 400 Bad Request.
 
 ```ruby
 class PeopleController < ActionController::Base
@@ -239,17 +241,17 @@ params.permit(:id)
 ```
 
 the key `:id` will pass the whitelisting if it appears in `params` and
-it has a permitted scalar value associated. Otherwise the key is going
+it has a permitted scalar value associated. Otherwise, the key is going
 to be filtered out, so arrays, hashes, or any other objects cannot be
 injected.
 
 The permitted scalar types are `String`, `Symbol`, `NilClass`,
 `Numeric`, `TrueClass`, `FalseClass`, `Date`, `Time`, `DateTime`,
-`StringIO`, `IO`, `ActionDispatch::Http::UploadedFile` and
+`StringIO`, `IO`, `ActionDispatch::Http::UploadedFile`, and
 `Rack::Test::UploadedFile`.
 
 To declare that the value in `params` must be an array of permitted
-scalar values map the key to an empty array:
+scalar values, map the key to an empty array:
 
 ```ruby
 params.permit(id: [])
@@ -262,14 +264,13 @@ used:
 params.require(:log_entry).permit!
 ```
 
-This will mark the `:log_entry` parameters hash and any sub-hash of it
-permitted. Extreme care should be taken when using `permit!` as it
-will allow all current and future model attributes to be
-mass-assigned.
+This will mark the `:log_entry` parameters hash and any sub-hash of it as
+permitted. Extreme care should be taken when using `permit!`, as it
+will allow all current and future model attributes to be mass-assigned.
 
 #### Nested Parameters
 
-You can also use permit on nested parameters, like:
+You can also use `permit` on nested parameters, like:
 
 ```ruby
 params.permit(:name, { emails: [] },
@@ -277,19 +278,19 @@ params.permit(:name, { emails: [] },
                          { family: [ :name ], hobbies: [] }])
 ```
 
-This declaration whitelists the `name`, `emails` and `friends`
+This declaration whitelists the `name`, `emails`, and `friends`
 attributes. It is expected that `emails` will be an array of permitted
-scalar values and that `friends` will be an array of resources with
-specific attributes : they should have a `name` attribute (any
+scalar values, and that `friends` will be an array of resources with
+specific attributes: they should have a `name` attribute (any
 permitted scalar values allowed), a `hobbies` attribute as an array of
 permitted scalar values, and a `family` attribute which is restricted
-to having a `name` (any permitted scalar values allowed, too).
+to having a `name` (any permitted scalar values allowed here, too).
 
 #### More Examples
 
-You want to also use the permitted attributes in the `new`
+You may want to also use the permitted attributes in your `new`
 action. This raises the problem that you can't use `require` on the
-root key because normally it does not exist when calling `new`:
+root key because, normally, it does not exist when calling `new`:
 
 ```ruby
 # using `fetch` you can supply a default and use
@@ -297,8 +298,8 @@ root key because normally it does not exist when calling `new`:
 params.fetch(:blog, {}).permit(:title, :author)
 ```
 
-`accepts_nested_attributes_for` allows you to update and destroy
-associated records. This is based on the `id` and `_destroy`
+The model class method `accepts_nested_attributes_for` allows you to
+update and destroy associated records. This is based on the `id` and `_destroy`
 parameters:
 
 ```ruby
@@ -306,7 +307,7 @@ parameters:
 params.require(:author).permit(:name, books_attributes: [:title, :id, :_destroy])
 ```
 
-Hashes with integer keys are treated differently and you can declare
+Hashes with integer keys are treated differently, and you can declare
 the attributes as if they were direct children. You get these kinds of
 parameters when you use `accepts_nested_attributes_for` in combination
 with a `has_many` association:
@@ -323,13 +324,13 @@ params.require(:book).permit(:title, chapters_attributes: [:title])
 #### Outside the Scope of Strong Parameters
 
 The strong parameter API was designed with the most common use cases
-in mind. It is not meant as a silver bullet to handle all your
-whitelisting problems. However you can easily mix the API with your
+in mind. It is not meant as a silver bullet to handle all of your
+whitelisting problems. However, you can easily mix the API with your
 own code to adapt to your situation.
 
 Imagine a scenario where you have parameters representing a product
 name and a hash of arbitrary data associated with that product, and
-you want to whitelist the product name attribute but also the whole
+you want to whitelist the product name attribute and also the whole
 data hash. The strong parameters API doesn't let you directly
 whitelist the whole of a nested hash with any keys, but you can use
 the keys of your nested hash to declare what to whitelist:
@@ -668,11 +669,11 @@ You may notice in the above code that we're using `render xml: @users`, not `ren
 Filters
 -------
 
-Filters are methods that are run before, after or "around" a controller action.
+Filters are methods that are run "before", "after" or "around" a controller action.
 
 Filters are inherited, so if you set a filter on `ApplicationController`, it will be run on every controller in your application.
 
-"Before" filters may halt the request cycle. A common "before" filter is one which requires that a user is logged in for an action to be run. You can define the filter method this way:
+"before" filters may halt the request cycle. A common "before" filter is one which requires that a user is logged in for an action to be run. You can define the filter method this way:
 
 ```ruby
 class ApplicationController < ActionController::Base
@@ -705,9 +706,9 @@ Now, the `LoginsController`'s `new` and `create` actions will work as before wit
 
 In addition to "before" filters, you can also run filters after an action has been executed, or both before and after.
 
-"After" filters are similar to "before" filters, but because the action has already been run they have access to the response data that's about to be sent to the client. Obviously, "after" filters cannot stop the action from running.
+"after" filters are similar to "before" filters, but because the action has already been run they have access to the response data that's about to be sent to the client. Obviously, "after" filters cannot stop the action from running.
 
-"Around" filters are responsible for running their associated actions by yielding, similar to how Rack middlewares work.
+"around" filters are responsible for running their associated actions by yielding, similar to how Rack middlewares work.
 
 For example, in a website where changes have an approval workflow an administrator could be able to preview them easily, just apply them within a transaction:
 
@@ -737,7 +738,7 @@ You can choose not to yield and build the response yourself, in which case the a
 
 While the most common way to use filters is by creating private methods and using *_action to add them, there are two other ways to do the same thing.
 
-The first is to use a block directly with the *_action methods. The block receives the controller as an argument, and the `require_login` filter from above could be rewritten to use a block:
+The first is to use a block directly with the *\_action methods. The block receives the controller as an argument. The `require_login` filter from above could be rewritten to use a block:
 
 ```ruby
 class ApplicationController < ActionController::Base
@@ -750,7 +751,7 @@ class ApplicationController < ActionController::Base
 end
 ```
 
-Note that the filter in this case uses `send` because the `logged_in?` method is private and the filter is not run in the scope of the controller. This is not the recommended way to implement this particular filter, but in more simple cases it might be useful.
+Note that the filter in this case uses `send` because the `logged_in?` method is private and the filter does not run in the scope of the controller. This is not the recommended way to implement this particular filter, but in more simple cases it might be useful.
 
 The second way is to use a class (actually, any object that responds to the right methods will do) to handle the filtering. This is useful in cases that are more complex and cannot be implemented in a readable and reusable way using the two other methods. As an example, you could rewrite the login filter again to use a class:
 
@@ -809,7 +810,7 @@ The [Security Guide](security.html) has more about this and a lot of other secur
 The Request and Response Objects
 --------------------------------
 
-In every controller there are two accessor methods pointing to the request and the response objects associated with the request cycle that is currently in execution. The `request` method contains an instance of `AbstractRequest` and the `response` method returns a response object representing what is going to be sent back to the client.
+In every controller there are two accessor methods pointing to the request and the response objects associated with the request cycle that is currently in execution. The `request` method contains an instance of `ActionDispatch::Request` and the `response` method returns a response object representing what is going to be sent back to the client.
 
 ### The `request` Object
 
@@ -1028,7 +1029,7 @@ There are a couple of things to notice in the above example. We need to make
 sure to close the response stream. Forgetting to close the stream will leave
 the socket open forever. We also have to set the content type to `text/event-stream`
 before we write to the response stream. This is because headers cannot be written
-after the response has been committed (when `response.committed` returns a truthy
+after the response has been committed (when `response.committed?` returns a truthy
 value), which occurs when you `write` or `commit` the response stream.
 
 #### Example Usage
@@ -1113,11 +1114,11 @@ Rescue
 
 Most likely your application is going to contain bugs or otherwise throw an exception that needs to be handled. For example, if the user follows a link to a resource that no longer exists in the database, Active Record will throw the `ActiveRecord::RecordNotFound` exception.
 
-Rails' default exception handling displays a "500 Server Error" message for all exceptions. If the request was made locally, a nice traceback and some added information gets displayed so you can figure out what went wrong and deal with it. If the request was remote Rails will just display a simple "500 Server Error" message to the user, or a "404 Not Found" if there was a routing error or a record could not be found. Sometimes you might want to customize how these errors are caught and how they're displayed to the user. There are several levels of exception handling available in a Rails application:
+Rails default exception handling displays a "500 Server Error" message for all exceptions. If the request was made locally, a nice traceback and some added information gets displayed so you can figure out what went wrong and deal with it. If the request was remote Rails will just display a simple "500 Server Error" message to the user, or a "404 Not Found" if there was a routing error or a record could not be found. Sometimes you might want to customize how these errors are caught and how they're displayed to the user. There are several levels of exception handling available in a Rails application:
 
 ### The Default 500 and 404 Templates
 
-By default a production application will render either a 404 or a 500 error message. These messages are contained in static HTML files in the `public` folder, in `404.html` and `500.html` respectively. You can customize these files to add some extra information and layout, but remember that they are static; i.e. you can't use RHTML or layouts in them, just plain HTML.
+By default a production application will render either a 404 or a 500 error message. These messages are contained in static HTML files in the `public` folder, in `404.html` and `500.html` respectively. You can customize these files to add some extra information and style, but remember that they are static HTML; i.e. you can't use ERB, SCSS, CoffeeScript, or layouts for them.
 
 ### `rescue_from`
 
@@ -1173,7 +1174,7 @@ end
 
 WARNING: You shouldn't do `rescue_from Exception` or `rescue_from StandardError` unless you have a particular reason as it will cause serious side-effects (e.g. you won't be able to see exception details and tracebacks during development).
 
-NOTE: Certain exceptions are only rescuable from the `ApplicationController` class, as they are raised before the controller gets initialized and the action gets executed. See Pratik Naik's [article](http://m.onkey.org/2008/7/20/rescue-from-dispatching) on the subject for more information.
+NOTE: Certain exceptions are only rescuable from the `ApplicationController` class, as they are raised before the controller gets initialized and the action gets executed. 
 
 Force HTTPS protocol
 --------------------
diff --git a/guides/source/action_mailer_basics.md b/guides/source/action_mailer_basics.md
index e55ff16495..4800cece82 100644
--- a/guides/source/action_mailer_basics.md
+++ b/guides/source/action_mailer_basics.md
@@ -326,7 +326,7 @@ key. The list of emails can be an array of email addresses or a single string
 with the addresses separated by commas.
 
 ```ruby
-class AdminMailer < ActionMailer::Base
+class AdminMailer < ApplicationMailer
   default to: Proc.new { Admin.pluck(:email) },
           from: 'notification@example.com'
 
@@ -344,7 +344,7 @@ The same format can be used to set carbon copy (Cc:) and blind carbon copy
 
 Sometimes you wish to show the name of the person instead of just their email
 address when they receive the email. The trick to doing that is to format the
-email address in the format `"Full Name <email>"`.
+email address in the format `"Full Name" <email>`.
 
 ```ruby
 def welcome_email(user)
@@ -442,6 +442,39 @@ end
 Will render the HTML part using the `my_layout.html.erb` file and the text part
 with the usual `user_mailer.text.erb` file if it exists.
 
+### Previewing Emails
+
+Action Mailer previews provide a way to see how emails look by visiting a
+special URL that renders them. In the above example, the preview class for
+`UserMailer` should be named `UserMailerPreview` and located in
+`test/mailers/previews/user_mailer_preview.rb`. To see the preview of
+`welcome_email`, implement a method that has the same name and call
+`UserMailer.welcome_email`:
+
+```ruby
+class UserMailerPreview < ActionMailer::Preview
+  def welcome_email
+    UserMailer.welcome_email(User.first)
+  end
+end
+```
+
+Then the preview will be available in <http://localhost:3000/rails/mailers/user_mailer/welcome_email>.
+
+If you change something in `app/views/user_mailer/welcome_email.html.erb`
+or the mailer itself, it'll automatically reload and render it so you can
+visually see the new style instantly. A list of previews are also available
+in <http://localhost:3000/rails/mailers>.
+
+By default, these preview classes live in `test/mailers/previews`.
+This can be configured using the `preview_path` option. For example, if you
+want to change it to `lib/mailer_previews`, you can configure it in
+`config/application.rb`:
+
+```ruby
+config.action_mailer.preview_path = "#{Rails.root}/lib/mailer_previews"
+```
+
 ### Generating URLs in Action Mailer Views
 
 Unlike controllers, the mailer instance doesn't have any context about the
@@ -470,7 +503,7 @@ You will need to use:
 
 By using the full URL, your links will now work in your emails.
 
-#### generating URLs with `url_for`
+#### Generating URLs with `url_for`
 
 `url_for` generate full URL by default in templates.
 
@@ -484,7 +517,7 @@ If you did not configure the `:host` option globally make sure to pass it to
             action: 'greeting') %>
 ```
 
-#### generating URLs with named routes
+#### Generating URLs with Named Routes
 
 Email clients have no web context and so paths have no base URL to form complete
 web addresses. Thus, you should always use the "_url" variant of named route
@@ -497,6 +530,27 @@ url helper.
 <%= user_url(@user, host: 'example.com') %>
 ```
 
+NOTE: non-`GET` links require [jQuery UJS](https://github.com/rails/jquery-ujs)
+and won't work in mailer templates. They will result in normal `GET` requests.
+
+### Adding images in Action Mailer Views
+
+Unlike controllers, the mailer instance doesn't have any context about the
+incoming request so you'll need to provide the `:asset_host` parameter yourself.
+
+As the `:asset_host` usually is consistent across the application you can
+configure it globally in config/application.rb:
+
+```ruby
+config.action_mailer.asset_host = 'http://example.com'
+```
+
+Now you can display an image inside your email.
+
+```ruby
+<%= image_tag 'image.jpg' %>
+```
+
 ### Sending Multipart Emails
 
 Action Mailer will automatically send multipart emails if you have different
@@ -660,7 +714,7 @@ files (environment.rb, production.rb, etc...)
 | Configuration | Description |
 |---------------|-------------|
 |`logger`|Generates information on the mailing run if available. Can be set to `nil` for no logging. Compatible with both Ruby's own `Logger` and `Log4r` loggers.|
-|`smtp_settings`|Allows detailed configuration for `:smtp` delivery method:<ul><li>`:address` - Allows you to use a remote mail server. Just change it from its default `"localhost"` setting.</li><li>`:port` - On the off chance that your mail server doesn't run on port 25, you can change it.</li><li>`:domain` - If you need to specify a HELO domain, you can do it here.</li><li>`:user_name` - If your mail server requires authentication, set the username in this setting.</li><li>`:password` - If your mail server requires authentication, set the password in this setting.</li><li>`:authentication` - If your mail server requires authentication, you need to specify the authentication type here. This is a symbol and one of `:plain`, `:login`, `:cram_md5`.</li><li>`:enable_starttls_auto` - Set this to `false` if there is a problem with your server certificate that you cannot resolve.</li></ul>|
+|`smtp_settings`|Allows detailed configuration for `:smtp` delivery method:<ul><li>`:address` - Allows you to use a remote mail server. Just change it from its default `"localhost"` setting.</li><li>`:port` - On the off chance that your mail server doesn't run on port 25, you can change it.</li><li>`:domain` - If you need to specify a HELO domain, you can do it here.</li><li>`:user_name` - If your mail server requires authentication, set the username in this setting.</li><li>`:password` - If your mail server requires authentication, set the password in this setting.</li><li>`:authentication` - If your mail server requires authentication, you need to specify the authentication type here. This is a symbol and one of `:plain` (will send the password in the clear), `:login` (will send password Base64 encoded) or `:cram_md5` (combines a Challenge/Response mechanism to exchange information and a cryptographic Message Digest 5 algorithm to hash important information)</li><li>`:enable_starttls_auto` - Detects if STARTTLS is enabled in your SMTP server and starts to use it. Defaults to `true`.</li><li>`:openssl_verify_mode` - When using TLS, you can set how OpenSSL checks the certificate. This is really useful if you need to validate a self-signed and/or a wildcard certificate. You can use the name of an OpenSSL verify constant ('none', 'peer', 'client_once', 'fail_if_no_peer_cert') or directly the constant (`OpenSSL::SSL::VERIFY_NONE`, `OpenSSL::SSL::VERIFY_PEER`, ...).</li></ul>|
 |`sendmail_settings`|Allows you to override options for the `:sendmail` delivery method.<ul><li>`:location` - The location of the sendmail executable. Defaults to `/usr/sbin/sendmail`.</li><li>`:arguments` - The command line arguments to be passed to sendmail. Defaults to `-i -t`.</li></ul>|
 |`raise_delivery_errors`|Whether or not errors should be raised if the email fails to be delivered. This only works if the external email server is configured for immediate delivery.|
 |`delivery_method`|Defines a delivery method. Possible values are:<ul><li>`:smtp` (default), can be configured by using `config.action_mailer.smtp_settings`.</li><li>`:sendmail`, can be configured by using `config.action_mailer.sendmail_settings`.</li><li>`:file`: save emails to files; can be configured by using `config.action_mailer.file_settings`.</li><li>`:test`: save emails to `ActionMailer::Base.deliveries` array.</li></ul>See [API docs](http://api.rubyonrails.org/classes/ActionMailer/Base.html) for more info.|
@@ -705,6 +759,9 @@ config.action_mailer.smtp_settings = {
   authentication:       'plain',
   enable_starttls_auto: true  }
 ```
+Note: As of July 15, 2014, Google increased [its security measures](https://support.google.com/accounts/answer/6010255) and now blocks attempts from apps it deems less secure.
+You can change your gmail settings [here](https://www.google.com/settings/security/lesssecureapps) to allow the attempts or
+use another ESP to send email by replacing 'smtp.gmail.com' above with the address of your provider.
 
 Mailer Testing
 --------------
diff --git a/guides/source/action_view_overview.md b/guides/source/action_view_overview.md
index 665a2b71ff..4b0e9bff7c 100644
--- a/guides/source/action_view_overview.md
+++ b/guides/source/action_view_overview.md
@@ -15,7 +15,7 @@ After reading this guide, you will know:
 What is Action View?
 --------------------
 
-Action View and Action Controller are the two major components of Action Pack. In Rails, web requests are handled by Action Pack, which splits the work into a controller part (performing the logic) and a view part (rendering a template). Typically, Action Controller will be concerned with communicating with the database and performing CRUD actions where necessary. Action View is then responsible for compiling the response.
+In Rails, web requests are handled by [Action Controller](action_controller_overview.html) and Action View. Typically, Action Controller will be concerned with communicating with the database and performing CRUD actions where necessary. Action View is then responsible for compiling the response.
 
 Action View templates are written using embedded Ruby in tags mingled with HTML. To avoid cluttering the templates with boilerplate code, a number of helper classes provide common behavior for forms, dates, and strings. It's also easy to add new helpers to your application as it evolves.
 
@@ -147,6 +147,39 @@ xml.rss("version" => "2.0", "xmlns:dc" => "http://purl.org/dc/elements/1.1/") do
 end
 ```
 
+#### Jbuilder
+[Jbuilder](https://github.com/rails/jbuilder) is a gem that's
+maintained by the Rails team and included in the default Rails Gemfile.
+It's similar to Builder, but is used to generate JSON, instead of XML.
+
+If you don't have it, you can add the following to your Gemfile:
+
+```ruby
+gem 'jbuilder'
+```
+
+A Jbuilder object named `json` is automatically made available to templates with
+a `.jbuilder` extension.
+
+Here is a basic example:
+
+```ruby
+json.name("Alex")
+json.email("alex@example.com")
+```
+
+would produce:
+
+```json
+{
+  "name": "Alex",
+  "email: "alex@example.com"
+}
+```
+
+See the [Jbuilder documention](https://github.com/rails/jbuilder#jbuilder) for
+more examples and information.
+
 #### Template Caching
 
 By default, Rails will compile each template to a method in order to render it. When you alter a template, Rails will check the file's modification time and recompile it in development mode.
@@ -182,7 +215,7 @@ One way to use partials is to treat them as the equivalent of subroutines; a way
 
 <p>Here are a few of our fine products:</p>
 <% @products.each do |product| %>
-  <%= render partial: "product", locals: {product: product} %>
+  <%= render partial: "product", locals: { product: product } %>
 <% end %>
 
 <%= render "shared/footer" %>
@@ -190,6 +223,22 @@ One way to use partials is to treat them as the equivalent of subroutines; a way
 
 Here, the `_ad_banner.html.erb` and `_footer.html.erb` partials could contain content that is shared among many pages in your application. You don't need to see the details of these sections when you're concentrating on a particular page.
 
+#### `render` without `partial` and `locals` options
+
+In the above example, `render` takes 2 options: `partial` and `locals`. But if
+these are the only options you want to pass, you can skip using these options.
+For example, instead of:
+
+```erb
+<%= render partial: "product", locals: { product: @product } %>
+```
+
+You can also do:
+
+```erb
+<%= render "product", product: @product %>
+```
+
 #### The `as` and `object` options
 
 By default `ActionView::Partials::PartialRenderer` has its object in a local variable with the same name as the template. So, given:
@@ -198,10 +247,11 @@ By default `ActionView::Partials::PartialRenderer` has its object in a local var
 <%= render partial: "product" %>
 ```
 
-within product we'll get `@product` in the local variable `product`, as if we had written:
+within `_product` partial we'll get `@product` in the local variable `product`,
+as if we had written:
 
 ```erb
-<%= render partial: "product", locals: {product: @product} %>
+<%= render partial: "product", locals: { product: @product } %>
 ```
 
 With the `as` option we can specify a different name for the local variable. For example, if we wanted it to be `item` instead of `product` we would do:
@@ -215,7 +265,7 @@ The `object` option can be used to directly specify which object is rendered int
 For example, instead of:
 
 ```erb
-<%= render partial: "product", locals: {product: @item} %>
+<%= render partial: "product", locals: { product: @item } %>
 ```
 
 we would do:
@@ -288,7 +338,7 @@ In the `show` template, we'll render the `_article` partial wrapped in the `box`
 **articles/show.html.erb**
 
 ```erb
-<%= render partial: 'article', layout: 'box', locals: {article: @article} %>
+<%= render partial: 'article', layout: 'box', locals: { article: @article } %>
 ```
 
 The `box` layout simply wraps the `_article` partial in a `div`:
@@ -301,26 +351,6 @@ The `box` layout simply wraps the `_article` partial in a `div`:
 </div>
 ```
 
-The `_article` partial wraps the article's `body` in a `div` with the `id` of the article using the `div_for` helper:
-
-**articles/_article.html.erb**
-
-```html+erb
-<%= div_for(article) do %>
-  <p><%= article.body %></p>
-<% end %>
-```
-
-this would output the following:
-
-```html
-<div class='box'>
-  <div id='article_1'>
-    <p>Partial Layouts are cool!</p>
-  </div>
-</div>
-```
-
 Note that the partial layout has access to the local `article` variable that was passed into the `render` call. However, unlike application-wide layouts, partial layouts still have the underscore prefix.
 
 You can also render a block of code within a partial layout instead of calling `yield`. For example, if we didn't have the `_article` partial, we could do this instead:
@@ -328,10 +358,10 @@ You can also render a block of code within a partial layout instead of calling `
 **articles/show.html.erb**
 
 ```html+erb
-<% render(layout: 'box', locals: {article: @article}) do %>
-  <%= div_for(article) do %>
+<% render(layout: 'box', locals: { article: @article }) do %>
+  <div>
     <p><%= article.body %></p>
-  <% end %>
+  </div>
 <% end %>
 ```
 
@@ -340,91 +370,41 @@ Supposing we use the same `_box` partial from above, this would produce the same
 View Paths
 ----------
 
-TODO...
-
-Overview of helpers provided by Action View
--------------------------------------------
-
-WIP: Not all the helpers are listed here. For a full list see the [API documentation](http://api.rubyonrails.org/classes/ActionView/Helpers.html)
-
-The following is only a brief overview summary of the helpers available in Action View. It's recommended that you review the [API Documentation](http://api.rubyonrails.org/classes/ActionView/Helpers.html), which covers all of the helpers in more detail, but this should serve as a good starting point.
-
-### RecordTagHelper
-
-This module provides methods for generating container tags, such as `div`, for your record. This is the recommended way of creating a container for render your Active Record object, as it adds an appropriate class and id attributes to that container. You can then refer to those containers easily by following the convention, instead of having to think about which class or id attribute you should use.
-
-#### content_tag_for
-
-Renders a container tag that relates to your Active Record Object.
-
-For example, given `@article` is the object of `Article` class, you can do:
-
-```html+erb
-<%= content_tag_for(:tr, @article) do %>
-  <td><%= @article.title %></td>
-<% end %>
-```
-
-This will generate this HTML output:
+When rendering a response, the controller needs to resolve where the different
+views are located. By default it only looks inside the `app/views` directory.
 
-```html
-<tr id="article_1234" class="article">
-  <td>Hello World!</td>
-</tr>
-```
+We can add other locations and give them a certain precedence when resolving
+paths using the `prepend_view_path` and `append_view_path` methods.
 
-You can also supply HTML attributes as an additional option hash. For example:
+### Prepend view path
 
-```html+erb
-<%= content_tag_for(:tr, @article, class: "frontpage") do %>
-  <td><%= @article.title %></td>
-<% end %>
-```
+This can be helpful for example, when we want to put views inside a different
+directory for subdomains.
 
-Will generate this HTML output:
+We can do this by using:
 
-```html
-<tr id="article_1234" class="article frontpage">
-  <td>Hello World!</td>
-</tr>
+```ruby
+prepend_view_path "app/views/#{request.subdomain}"
 ```
 
-You can pass a collection of Active Record objects. This method will loop through your objects and create a container for each of them. For example, given `@articles` is an array of two `Article` objects:
+Then Action View will look first in this directory when resolving views.
 
-```html+erb
-<%= content_tag_for(:tr, @articles) do |article| %>
-  <td><%= article.title %></td>
-<% end %>
-```
+### Append view path
 
-Will generate this HTML output:
+Similarly, we can append paths:
 
-```html
-<tr id="article_1234" class="article">
-  <td>Hello World!</td>
-</tr>
-<tr id="article_1235" class="article">
-  <td>Ruby on Rails Rocks!</td>
-</tr>
+```ruby
+append_view_path "app/views/direct"
 ```
 
-#### div_for
-
-This is actually a convenient method which calls `content_tag_for` internally with `:div` as the tag name. You can pass either an Active Record object or a collection of objects. For example:
+This will add `app/views/direct` to the end of the lookup paths.
 
-```html+erb
-<%= div_for(@article, class: "frontpage") do %>
-  <td><%= @article.title %></td>
-<% end %>
-```
+Overview of helpers provided by Action View
+-------------------------------------------
 
-Will generate this HTML output:
+WIP: Not all the helpers are listed here. For a full list see the [API documentation](http://api.rubyonrails.org/classes/ActionView/Helpers.html)
 
-```html
-<div id="article_1234" class="article frontpage">
-  <td>Hello World!</td>
-</div>
-```
+The following is only a brief overview summary of the helpers available in Action View. It's recommended that you review the [API Documentation](http://api.rubyonrails.org/classes/ActionView/Helpers.html), which covers all of the helpers in more detail, but this should serve as a good starting point.
 
 ### AssetTagHelper
 
@@ -437,39 +417,13 @@ config.action_controller.asset_host = "assets.example.com"
 image_tag("rails.png") # => <img src="http://assets.example.com/images/rails.png" alt="Rails" />
 ```
 
-#### register_javascript_expansion
-
-Register one or more JavaScript files to be included when symbol is passed to javascript_include_tag. This method is typically intended to be called from plugin initialization to register JavaScript files that the plugin installed in `vendor/assets/javascripts`.
-
-```ruby
-ActionView::Helpers::AssetTagHelper.register_javascript_expansion monkey: ["head", "body", "tail"]
-
-javascript_include_tag :monkey # =>
-  <script src="/assets/head.js"></script>
-  <script src="/assets/body.js"></script>
-  <script src="/assets/tail.js"></script>
-```
-
-#### register_stylesheet_expansion
-
-Register one or more stylesheet files to be included when symbol is passed to `stylesheet_link_tag`. This method is typically intended to be called from plugin initialization to register stylesheet files that the plugin installed in `vendor/assets/stylesheets`.
-
-```ruby
-ActionView::Helpers::AssetTagHelper.register_stylesheet_expansion monkey: ["head", "body", "tail"]
-
-stylesheet_link_tag :monkey # =>
-  <link href="/assets/head.css" media="screen" rel="stylesheet" />
-  <link href="/assets/body.css" media="screen" rel="stylesheet" />
-  <link href="/assets/tail.css" media="screen" rel="stylesheet" />
-```
-
 #### auto_discovery_link_tag
 
 Returns a link tag that browsers and feed readers can use to auto-detect an RSS or Atom feed.
 
 ```ruby
-auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", {title: "RSS Feed"}) # =>
-  <link rel="alternate" type="application/rss+xml" title="RSS Feed" href="http://www.example.com/feed" />
+auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", { title: "RSS Feed" }) # =>
+  <link rel="alternate" type="application/rss+xml" title="RSS Feed" href="http://www.example.com/feed.rss" />
 ```
 
 #### image_path
@@ -553,7 +507,7 @@ Returns a stylesheet link tag for the sources specified as arguments. If you don
 stylesheet_link_tag "application" # => <link href="/assets/application.css" media="screen" rel="stylesheet" />
 ```
 
-You can also include all styles in the stylesheet directory using :all as the source:
+You can also include all styles in the stylesheet directory using `:all` as the source:
 
 ```ruby
 stylesheet_link_tag :all
@@ -568,7 +522,7 @@ stylesheet_link_tag :all, cache: true
 
 #### stylesheet_path
 
-Computes the path to a stylesheet asset in the `app/assets/stylesheets` directory. If the source filename has no extension, .css will be appended. Full paths from the document root will be passed through. Used internally by stylesheet_link_tag to build the stylesheet path.
+Computes the path to a stylesheet asset in the `app/assets/stylesheets` directory. If the source filename has no extension, `.css` will be appended. Full paths from the document root will be passed through. Used internally by stylesheet_link_tag to build the stylesheet path.
 
 ```ruby
 stylesheet_path "application" # => /assets/application.css
@@ -612,7 +566,7 @@ end
 ```ruby
 atom_feed do |feed|
   feed.title("Articles Index")
-  feed.updated((@articles.first.created_at))
+  feed.updated(@articles.first.created_at)
 
   @articles.each do |article|
     feed.entry(article) do |entry|
@@ -786,7 +740,7 @@ Returns a select tag with options for each of the minutes 0 through 59 with the
 
 ```ruby
 # Generates a select field for minutes that defaults to the minutes for the time provided.
-select_minute(Time.now + 6.hours)
+select_minute(Time.now + 10.minutes)
 ```
 
 #### select_month
@@ -804,7 +758,7 @@ Returns a select tag with options for each of the seconds 0 through 59 with the
 
 ```ruby
 # Generates a select field for seconds that defaults to the seconds for the time provided
-select_second(Time.now + 16.minutes)
+select_second(Time.now + 16.seconds)
 ```
 
 #### select_time
@@ -850,7 +804,7 @@ time_select("order", "submitted")
 Returns a `pre` tag that has object dumped by YAML. This creates a very readable way to inspect an object.
 
 ```ruby
-my_hash = {'first' => 1, 'second' => 'two', 'third' => [1,2,3]}
+my_hash = { 'first' => 1, 'second' => 'two', 'third' => [1,2,3] }
 debug(my_hash)
 ```
 
@@ -869,13 +823,13 @@ third:
 
 Form helpers are designed to make working with models much easier compared to using just standard HTML elements by providing a set of methods for creating forms based on your models. This helper generates the HTML for forms, providing a method for each sort of input (e.g., text, password, select, and so on). When the form is submitted (i.e., when the user hits the submit button or form.submit is called via JavaScript), the form inputs will be bundled into the params object and passed back to the controller.
 
-There are two types of form helpers: those that specifically work with model attributes and those that don't. This helper deals with those that work with model attributes; to see an example of form helpers that don't work with model attributes, check the ActionView::Helpers::FormTagHelper documentation.
+There are two types of form helpers: those that specifically work with model attributes and those that don't. This helper deals with those that work with model attributes; to see an example of form helpers that don't work with model attributes, check the `ActionView::Helpers::FormTagHelper` documentation.
 
-The core method of this helper, form_for, gives you the ability to create a form for a model instance; for example, let's say that you have a model Person and want to create a new instance of it:
+The core method of this helper, `form_for`, gives you the ability to create a form for a model instance; for example, let's say that you have a model Person and want to create a new instance of it:
 
 ```html+erb
 # Note: a @person variable will have been created in the controller (e.g. @person = Person.new)
-<%= form_for @person, url: {action: "create"} do |f| %>
+<%= form_for @person, url: { action: "create" } do |f| %>
   <%= f.text_field :first_name %>
   <%= f.text_field :last_name %>
   <%= submit_tag 'Create' %>
@@ -895,7 +849,7 @@ The HTML generated for this would be:
 The params object created when this form is submitted would look like:
 
 ```ruby
-{"action" => "create", "controller" => "people", "person" => {"first_name" => "William", "last_name" => "Smith"}}
+{ "action" => "create", "controller" => "people", "person" => { "first_name" => "William", "last_name" => "Smith" } }
 ```
 
 The params hash has a nested person value, which can therefore be accessed with params[:person] in the controller.
@@ -913,10 +867,10 @@ check_box("article", "validated")
 
 #### fields_for
 
-Creates a scope around a specific model object like form_for, but doesn't create the form tags themselves. This makes fields_for suitable for specifying additional model objects in the same form:
+Creates a scope around a specific model object like `form_for`, but doesn't create the form tags themselves. This makes `fields_for` suitable for specifying additional model objects in the same form:
 
 ```html+erb
-<%= form_for @person, url: {action: "update"} do |person_form| %>
+<%= form_for @person, url: { action: "update" } do |person_form| %>
   First name: <%= person_form.text_field :first_name %>
   Last name : <%= person_form.text_field :last_name %>
 
@@ -1051,7 +1005,7 @@ end
 Sample usage (selecting the associated Author for an instance of Article, `@article`):
 
 ```ruby
-collection_select(:article, :author_id, Author.all, :id, :name_with_initial, {prompt: true})
+collection_select(:article, :author_id, Author.all, :id, :name_with_initial, { prompt: true })
 ```
 
 If `@article.author_id` is 1, this would return:
@@ -1138,14 +1092,6 @@ If `@article.author_ids` is [1], this would return:
 <input name="article[author_ids][]" type="hidden" value="" />
 ```
 
-#### country_options_for_select
-
-Returns a string of option tags for pretty much any country in the world.
-
-#### country_select
-
-Returns select and option tags for the given object and method, using country_options_for_select to generate the list of option tags.
-
 #### option_groups_from_collection_for_select
 
 Returns a string of `option` tags, like `options_from_collection_for_select`, but groups them by `optgroup` tags based on the object relationships of the arguments.
@@ -1207,7 +1153,7 @@ Returns a string of option tags that have been compiled by iterating over the `c
 # options_from_collection_for_select(collection, value_method, text_method, selected = nil)
 ```
 
-For example, imagine a loop iterating over each person in @project.people to generate an input tag:
+For example, imagine a loop iterating over each person in `@project.people` to generate an input tag:
 
 ```ruby
 options_from_collection_for_select(@project.people, "id", "name")
@@ -1223,7 +1169,7 @@ Create a select tag and a series of contained option tags for the provided objec
 Example:
 
 ```ruby
-select("article", "person_id", Person.all.collect {|p| [ p.name, p.id ] }, {include_blank: true})
+select("article", "person_id", Person.all.collect { |p| [ p.name, p.id ] }, { include_blank: true })
 ```
 
 If `@article.person_id` is 1, this would become:
@@ -1232,8 +1178,8 @@ If `@article.person_id` is 1, this would become:
 <select name="article[person_id]">
   <option value=""></option>
   <option value="1" selected="selected">David</option>
-  <option value="2">Sam</option>
-  <option value="3">Tobias</option>
+  <option value="2">Eileen</option>
+  <option value="3">Rafael</option>
 </select>
 ```
 
@@ -1286,7 +1232,7 @@ Creates a field set for grouping HTML form elements.
 Creates a file upload field.
 
 ```html+erb
-<%= form_tag({action:"post"}, multipart: true) do %>
+<%= form_tag({ action: "post" }, multipart: true) do %>
   <label for="file">File to Upload</label> <%= file_field_tag "file" %>
   <%= submit_tag %>
 <% end %>
@@ -1301,7 +1247,7 @@ file_field_tag 'attachment'
 
 #### form_tag
 
-Starts a form tag that points the action to an url configured with `url_for_options` just like `ActionController::Base#url_for`.
+Starts a form tag that points the action to a url configured with `url_for_options` just like `ActionController::Base#url_for`.
 
 ```html+erb
 <%= form_tag '/articles' do %>
@@ -1422,22 +1368,6 @@ date_field_tag "dob"
 
 Provides functionality for working with JavaScript in your views.
 
-#### button_to_function
-
-Returns a button that'll trigger a JavaScript function using the onclick handler. Examples:
-
-```ruby
-button_to_function "Greeting", "alert('Hello world!')"
-button_to_function "Delete", "if (confirm('Really?')) do_delete()"
-button_to_function "Details" do |page|
-  page[:details].visual_effect :toggle_slide
-end
-```
-
-#### define_javascript_functions
-
-Includes the Action Pack JavaScript libraries inside a single `script` tag.
-
 #### escape_javascript
 
 Escape carrier returns and single and double quotes for JavaScript segments.
@@ -1458,15 +1388,6 @@ alert('All is good')
 </script>
 ```
 
-#### link_to_function
-
-Returns a link that will trigger a JavaScript function using the onclick handler and return false after the fact.
-
-```ruby
-link_to_function "Greeting", "alert('Hello world!')"
-# => <a onclick="alert('Hello world!'); return false;" href="#">Greeting</a>
-```
-
 ### NumberHelper
 
 Provides methods for converting numbers into formatted strings. Methods are provided for phone numbers, currency, percentage, precision, positional notation, and file size.
@@ -1533,7 +1454,7 @@ This sanitize helper will HTML encode all tags and strip all attributes that are
 sanitize @article.body
 ```
 
-If either the :attributes or :tags options are passed, only the mentioned tags and attributes are allowed and nothing else.
+If either the `:attributes` or `:tags` options are passed, only the mentioned attributes and tags are allowed and nothing else.
 
 ```ruby
 sanitize @article.body, tags: %w(table tr td), attributes: %w(id class style)
@@ -1555,12 +1476,12 @@ Sanitizes a block of CSS code.
 Strips all link tags from text leaving just the link text.
 
 ```ruby
-strip_links("<a href="http://rubyonrails.org">Ruby on Rails</a>")
+strip_links('<a href="http://rubyonrails.org">Ruby on Rails</a>')
 # => Ruby on Rails
 ```
 
 ```ruby
-strip_links("emails to <a href="mailto:me@email.com">me@email.com</a>.")
+strip_links('emails to <a href="mailto:me@email.com">me@email.com</a>.')
 # => emails to me@email.com.
 ```
 
@@ -1601,7 +1522,7 @@ details can be found in the [Rails Security Guide](security.html#cross-site-requ
 Localized Views
 ---------------
 
-Action View has the ability render different templates depending on the current locale.
+Action View has the ability to render different templates depending on the current locale.
 
 For example, suppose you have a `ArticlesController` with a show action. By default, calling this action will render `app/views/articles/show.html.erb`. But if you set `I18n.locale = :de`, then `app/views/articles/show.de.html.erb` will be rendered instead. If the localized template isn't present, the undecorated version will be used. This means you're not required to provide localized views for all cases, but they will be preferred and used if available.
 
diff --git a/guides/source/active_job_basics.md b/guides/source/active_job_basics.md
index 4d1625b28d..a114686f0f 100644
--- a/guides/source/active_job_basics.md
+++ b/guides/source/active_job_basics.md
@@ -4,14 +4,14 @@ Active Job Basics
 =================
 
 This guide provides you with all you need to get started in creating,
-enqueueing and executing background jobs.
+enqueuing and executing background jobs.
 
 After reading this guide, you will know:
 
 * How to create jobs.
 * How to enqueue jobs.
 * How to run jobs in the background.
-* How to send emails from your application async.
+* How to send emails from your application asynchronously.
 
 --------------------------------------------------------------------------------
 
@@ -20,7 +20,7 @@ Introduction
 ------------
 
 Active Job is a framework for declaring jobs and making them run on a variety
-of queueing backends. These jobs can be everything from regularly scheduled
+of queuing backends. These jobs can be everything from regularly scheduled
 clean-ups, to billing charges, to mailings. Anything that can be chopped up
 into small units of work and run in parallel, really.
 
@@ -28,11 +28,14 @@ into small units of work and run in parallel, really.
 The Purpose of Active Job
 -----------------------------
 The main point is to ensure that all Rails apps will have a job infrastructure
-in place, even if it's in the form of an "immediate runner". We can then have
-framework features and other gems build on top of that, without having to
-worry about API differences between various job runners such as Delayed Job
-and Resque. Picking your queuing backend becomes more of an operational concern,
-then. And you'll be able to switch between them without having to rewrite your jobs.
+in place. We can then have framework features and other gems build on top of that,
+without having to worry about API differences between various job runners such as
+Delayed Job and Resque. Picking your queuing backend becomes more of an operational
+concern, then. And you'll be able to switch between them without having to rewrite
+your jobs.
+
+NOTE: Rails by default comes with an "immediate runner" queuing implementation.
+That means that each job that has been enqueued will run immediately.
 
 
 Creating a Job
@@ -67,49 +70,59 @@ Here's what a job looks like:
 class GuestsCleanupJob < ActiveJob::Base
   queue_as :default
 
-  def perform(*args)
+  def perform(*guests)
     # Do something later
   end
 end
 ```
 
+Note that you can define `perform` with as many arguments as you want.
+
 ### Enqueue the Job
 
 Enqueue a job like so:
 
 ```ruby
-# Enqueue a job to be performed as soon the queueing system is
+# Enqueue a job to be performed as soon the queuing system is
 # free.
-MyJob.perform_later record
+GuestsCleanupJob.perform_later guest
 ```
 
 ```ruby
 # Enqueue a job to be performed tomorrow at noon.
-MyJob.set(wait_until: Date.tomorrow.noon).perform_later(record)
+GuestsCleanupJob.set(wait_until: Date.tomorrow.noon).perform_later(guest)
 ```
 
 ```ruby
 # Enqueue a job to be performed 1 week from now.
-MyJob.set(wait: 1.week).perform_later(record)
+GuestsCleanupJob.set(wait: 1.week).perform_later(guest)
 ```
 
-That's it!
+```ruby
+# `perform_now` and `perform_later` will call `perform` under the hood so
+# you can pass as many arguments as defined in the latter.
+GuestsCleanupJob.perform_later(guest1, guest2, filter: 'some_filter')
+```
 
+That's it!
 
 Job Execution
 -------------
 
-If no adapter is set, the job is immediately executed.
+For enqueuing and executing jobs you need to set up a queuing backend, that is to
+say you need to decide for a 3rd-party queuing library that Rails should use.
+Rails itself does not provide a sophisticated queuing system and just executes the
+job immediately if no adapter is set.
 
 ### Backends
 
-Active Job has built-in adapters for multiple queueing backends (Sidekiq,
+Active Job has built-in adapters for multiple queuing backends (Sidekiq,
 Resque, Delayed Job and others). To get an up-to-date list of the adapters
 see the API Documentation for [ActiveJob::QueueAdapters](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html).
 
 ### Setting the Backend
 
-You can easily set your queueing backend:
+You can easily set your queuing backend:
 
 ```ruby
 # config/application.rb
@@ -123,6 +136,19 @@ module YourApp
 end
 ```
 
+### Starting the Backend
+
+Since jobs run in parallel to your Rails application, most queuing libraries
+require that you start a library-specific queuing service (in addition to
+starting your Rails app) for the job processing to work. Refer to library
+documentation for instructions on starting your queue backend.
+
+Here is a noncomprehensive list of documentation:
+
+- [Sidekiq](https://github.com/mperham/sidekiq/wiki/Active-Job)
+- [Resque](https://github.com/resque/resque/wiki/ActiveJob)
+- [Sucker Punch](https://github.com/brandonhilkert/sucker_punch#active-job)
+- [Queue Classic](https://github.com/QueueClassic/queue_classic#active-job)
 
 Queues
 ------
@@ -205,14 +231,14 @@ class ProcessVideoJob < ActiveJob::Base
   end
 
   def perform(video)
-    # do process video
+    # Do process video
   end
 end
 
 ProcessVideoJob.perform_later(Video.last)
 ```
 
-NOTE: Make sure your queueing backend "listens" on your queue name. For some
+NOTE: Make sure your queuing backend "listens" on your queue name. For some
 backends you need to specify the queues to listen to.
 
 
@@ -238,13 +264,13 @@ class GuestsCleanupJob < ActiveJob::Base
   queue_as :default
 
   before_enqueue do |job|
-    # do something with the job instance
+    # Do something with the job instance
   end
 
   around_perform do |job, block|
-    # do something before perform
+    # Do something before perform
     block.call
-    # do something after perform
+    # Do something after perform
   end
 
   def perform
@@ -270,6 +296,19 @@ UserMailer.welcome(@user).deliver_later
 ```
 
 
+Internationalization
+--------------------
+
+Each job uses the `I18n.locale` set when the job was created. Useful if you send
+emails asynchronously:
+
+```ruby
+I18n.locale = :eo
+
+UserMailer.welcome(@user).deliver_later # Email will be localized to Esperanto.
+```
+
+
 GlobalID
 --------
 
@@ -311,7 +350,7 @@ class GuestsCleanupJob < ActiveJob::Base
   queue_as :default
 
   rescue_from(ActiveRecord::RecordNotFound) do |exception|
-   # do something with the exception
+   # Do something with the exception
   end
 
   def perform
@@ -319,3 +358,17 @@ class GuestsCleanupJob < ActiveJob::Base
   end
 end
 ```
+
+### Deserialization
+
+GlobalID allows serializing full Active Record objects passed to `#perform`.
+
+If a passed record is deleted after the job is enqueued but before the `#perform`
+method is called Active Job will raise an `ActiveJob::DeserializationError`
+exception.
+
+Job Testing
+--------------
+
+You can find detailed instructions on how to test your jobs in the
+[testing guide](testing.html#testing-jobs).
diff --git a/guides/source/active_model_basics.md b/guides/source/active_model_basics.md
index 4b2bfaee2f..fe2501bd87 100644
--- a/guides/source/active_model_basics.md
+++ b/guides/source/active_model_basics.md
@@ -8,12 +8,12 @@ classes. Active Model allows for Action Pack helpers to interact with
 plain Ruby objects. Active Model also helps build custom ORMs for use
 outside of the Rails framework.
 
-After reading this guide, you will be able to add to plain Ruby objects:
+After reading this guide, you will know: 
 
-* The ability to behave like an Active Record model.
-* Callbacks and validations like Active Record.
-* Serializers.
-* Integration with the Rails internationalization (i18n) framework.
+* How an Active Record model behaves.
+* How Callbacks and validations work. 
+* How serializers work.
+* The Rails internationalization (i18n) framework.
 
 --------------------------------------------------------------------------------
 
@@ -156,7 +156,7 @@ person.changed? # => false
 person.first_name = "First Name"
 person.first_name # => "First Name"
 
-# returns if any attribute has changed.
+# returns true if any of the attributes have unsaved changes, false otherwise.
 person.changed? # => true
 
 # returns a list of attributes that have changed before saving.
@@ -197,7 +197,7 @@ person.last_name_change # => nil
 
 ### Validations
 
-`ActiveModel::Validations` module adds the ability to validate class objects
+The `ActiveModel::Validations` module adds the ability to validate class objects
 like in Active Record.
 
 ```ruby
@@ -292,7 +292,7 @@ objects.
 
 ### Serialization
 
-`ActiveModel::Serialization` provides a basic serialization for your object.
+`ActiveModel::Serialization` provides basic serialization for your object.
 You need to declare an attributes hash which contains the attributes you want to
 serialize. Attributes must be strings, not symbols.
 
@@ -319,9 +319,8 @@ person.serializable_hash   # => {"name"=>"Bob"}
 
 #### ActiveModel::Serializers
 
-Rails provides two serializers `ActiveModel::Serializers::JSON` and
-`ActiveModel::Serializers::Xml`. Both of these modules automatically include
-the `ActiveModel::Serialization`.
+Rails provides a `ActiveModel::Serializers::JSON` serializer.
+This module automatically include the `ActiveModel::Serialization`.
 
 ##### ActiveModel::Serializers::JSON
 
@@ -340,7 +339,7 @@ class Person
 end
 ```
 
-With the `as_json` you have a hash representing the model.
+With the `as_json` method you have a hash representing the model.
 
 ```ruby
 person = Person.new
@@ -379,62 +378,6 @@ person.from_json(json) # => #<Person:0x00000100c773f0 @name="Bob">
 person.name            # => "Bob"
 ```
 
-##### ActiveModel::Serializers::Xml
-
-To use the `ActiveModel::Serializers::Xml` you only need to change from
-`ActiveModel::Serialization` to `ActiveModel::Serializers::Xml`.
-
-```ruby
-class Person
-  include ActiveModel::Serializers::Xml
-
-  attr_accessor :name
-
-  def attributes
-    {'name' => nil}
-  end
-end
-```
-
-With the `to_xml` you have an XML representing the model.
-
-```ruby
-person = Person.new
-person.to_xml # => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<person>\n  <name nil=\"true\"/>\n</person>\n"
-person.name = "Bob"
-person.to_xml # => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<person>\n  <name>Bob</name>\n</person>\n"
-```
-
-From an XML string you define the attributes of the model.
-You need to have the `attributes=` method defined on your class:
-
-```ruby
-class Person
-  include ActiveModel::Serializers::Xml
-
-  attr_accessor :name
-
-  def attributes=(hash)
-    hash.each do |key, value|
-      send("#{key}=", value)
-    end
-  end
-
-  def attributes
-    {'name' => nil}
-  end
-end
-```
-
-Now it is possible to create an instance of person and set the attributes using `from_xml`.
-
-```ruby
-xml = { name: 'Bob' }.to_xml
-person = Person.new
-person.from_xml(xml) # => #<Person:0x00000100c773f0 @name="Bob">
-person.name          # => "Bob"
-```
-
 ### Translation
 
 `ActiveModel::Translation` provides integration between your object and the Rails
@@ -465,7 +408,7 @@ Person.human_attribute_name('name') # => "Nome"
 
 ### Lint Tests
 
-`ActiveModel::Lint::Tests` allow you to test whether an object is compliant with
+`ActiveModel::Lint::Tests` allows you to test whether an object is compliant with
 the Active Model API.
 
 * app/models/person.rb
@@ -518,14 +461,14 @@ an accessor named `password` with certain validations on it.
 
 #### Requirements
 
-`ActiveModel::SecurePassword` depends on the [`bcrypt`](https://github.com/codahale/bcrypt-ruby 'BCrypt'),
+`ActiveModel::SecurePassword` depends on [`bcrypt`](https://github.com/codahale/bcrypt-ruby 'BCrypt'),
 so include this gem in your Gemfile to use `ActiveModel::SecurePassword` correctly.
 In order to make this work, the model must have an accessor named `password_digest`.
 The `has_secure_password` will add the following validations on the `password` accessor:
 
 1. Password should be present.
 2. Password should be equal to its confirmation.
-3. This maximum length of a password is 72 (required by `bcrypt` on which ActiveModel::SecurePassword depends)
+3. The maximum length of a password is 72 (required by `bcrypt` on which ActiveModel::SecurePassword depends)
 
 #### Examples
 
@@ -546,7 +489,7 @@ person.password = 'aditya'
 person.password_confirmation = 'nomatch'
 person.valid? # => false
 
-# When the length of password, exceeds 72.
+# When the length of password exceeds 72.
 person.password = person.password_confirmation = 'a' * 100
 person.valid? # => false
 
diff --git a/guides/source/active_record_basics.md b/guides/source/active_record_basics.md
index a5196e481e..dafbe17bbd 100644
--- a/guides/source/active_record_basics.md
+++ b/guides/source/active_record_basics.md
@@ -20,7 +20,7 @@ After reading this guide, you will know:
 What is Active Record?
 ----------------------
 
-Active Record is the M in [MVC](getting_started.html#the-mvc-architecture) - the
+Active Record is the M in [MVC](http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller) - the
 model - which is the layer of the system responsible for representing business
 data and logic. Active Record facilitates the creation and use of business
 objects whose data requires persistent storage to a database. It is an
@@ -38,7 +38,7 @@ object on how to write to and read from the database.
 
 ### Object Relational Mapping
 
-Object-Relational Mapping, commonly referred to as its abbreviation ORM, is
+Object Relational Mapping, commonly referred to as its abbreviation ORM, is
 a technique that connects the rich objects of an application to tables in
 a relational database management system. Using ORM, the properties and
 relationships of the objects in an application can be easily stored and
@@ -74,8 +74,8 @@ By default, Active Record uses some naming conventions to find out how the
 mapping between models and database tables should be created. Rails will
 pluralize your class names to find the respective database table. So, for
 a class `Book`, you should have a database table called **books**. The Rails
-pluralization mechanisms are very powerful, being capable to pluralize (and
-singularize) both regular and irregular words. When using class names composed
+pluralization mechanisms are very powerful, being capable of pluralizing (and
+singularizing) both regular and irregular words. When using class names composed
 of two or more words, the model class name should follow the Ruby conventions,
 using the CamelCase form, while the table name must contain the words separated
 by underscores. Examples:
@@ -122,7 +122,7 @@ to Active Record instances:
 * `(association_name)_type` - Stores the type for
   [polymorphic associations](association_basics.html#polymorphic-associations).
 * `(table_name)_count` - Used to cache the number of belonging objects on
-  associations. For example, a `comments_count` column in a `Articles` class that
+  associations. For example, a `comments_count` column in an `Article` class that
   has many instances of `Comment` will cache the number of existent comments
   for each article.
 
@@ -142,7 +142,7 @@ end
 This will create a `Product` model, mapped to a `products` table at the
 database. By doing this you'll also have the ability to map the columns of each
 row in that table with the attributes of the instances of your model. Suppose
-that the `products` table was created using an SQL sentence like:
+that the `products` table was created using an SQL statement like:
 
 ```sql
 CREATE TABLE products (
@@ -173,18 +173,18 @@ name that should be used:
 
 ```ruby
 class Product < ActiveRecord::Base
-  self.table_name = "PRODUCT"
+  self.table_name = "my_products"
 end
 ```
 
 If you do so, you will have to define manually the class name that is hosting
-the fixtures (class_name.yml) using the `set_fixture_class` method in your test
+the fixtures (my_products.yml) using the `set_fixture_class` method in your test
 definition:
 
 ```ruby
-class FunnyJoke < ActiveSupport::TestCase
-  set_fixture_class funny_jokes: Joke
-  fixtures :funny_jokes
+class ProductTest < ActiveSupport::TestCase
+  set_fixture_class my_products: Product
+  fixtures :my_products
   ...
 end
 ```
@@ -260,7 +260,7 @@ david = User.find_by(name: 'David')
 
 ```ruby
 # find all users named David who are Code Artists and sort by created_at in reverse chronological order
-users = User.where(name: 'David', occupation: 'Code Artist').order('created_at DESC')
+users = User.where(name: 'David', occupation: 'Code Artist').order(created_at: :desc)
 ```
 
 You can learn more about querying an Active Record model in the [Active Record
diff --git a/guides/source/active_record_callbacks.md b/guides/source/active_record_callbacks.md
index e65ab802c0..13989a3b33 100644
--- a/guides/source/active_record_callbacks.md
+++ b/guides/source/active_record_callbacks.md
@@ -68,7 +68,7 @@ class User < ActiveRecord::Base
 
   protected
     def normalize_name
-      self.name = self.name.downcase.titleize
+      self.name = name.downcase.titleize
     end
 
     def set_location
diff --git a/guides/source/active_record_migrations.md b/guides/source/active_record_migrations.md
index 97cabc1728..67881e6087 100644
--- a/guides/source/active_record_migrations.md
+++ b/guides/source/active_record_migrations.md
@@ -241,7 +241,7 @@ generates
 ```ruby
 class AddUserRefToProducts < ActiveRecord::Migration
   def change
-    add_reference :products, :user, index: true
+    add_reference :products, :user, index: true, foreign_key: true
   end
 end
 ```
@@ -357,8 +357,8 @@ will append `ENGINE=BLACKHOLE` to the SQL statement used to create the table
 
 ### Creating a Join Table
 
-Migration method `create_join_table` creates a HABTM join table. A typical use
-would be:
+The migration method `create_join_table` creates an HABTM (has and belongs to
+many) join table. A typical use would be:
 
 ```ruby
 create_join_table :products, :categories
@@ -367,23 +367,21 @@ create_join_table :products, :categories
 which creates a `categories_products` table with two columns called
 `category_id` and `product_id`. These columns have the option `:null` set to
 `false` by default. This can be overridden by specifying the `:column_options`
-option.
+option:
 
 ```ruby
-create_join_table :products, :categories, column_options: {null: true}
+create_join_table :products, :categories, column_options: { null: true }
 ```
 
-will create the `product_id` and `category_id` with the `:null` option as
-`true`.
-
-You can pass the option `:table_name` when you want to customize the table
-name. For example:
+By default, the name of the join table comes from the union of the first two
+arguments provided to create_join_table, in alphabetical order.
+To customize the name of the table, provide a `:table_name` option:
 
 ```ruby
 create_join_table :products, :categories, table_name: :categorization
 ```
 
-will create a `categorization` table.
+creates a `categorization` table.
 
 `create_join_table` also accepts a block, which you can use to add indices
 (which are not created by default) or additional columns:
@@ -423,21 +421,23 @@ change_column :products, :part_number, :text
 ```
 
 This changes the column `part_number` on products table to be a `:text` field.
+Note that `change_column` command is irreversible.
 
 Besides `change_column`, the `change_column_null` and `change_column_default`
-methods are used specifically to change the null and default values of a
-column.
+methods are used specifically to change a not null constraint and default
+values of a column.
 
 ```ruby
 change_column_null :products, :name, false
-change_column_default :products, :approved, false
+change_column_default :products, :approved, from: true, to: false
 ```
 
 This sets `:name` field on products to a `NOT NULL` column and the default
-value of the `:approved` field to false.
+value of the `:approved` field from true to false.
 
-TIP: Unlike `change_column` (and `change_column_default`), `change_column_null`
-is reversible.
+Note: You could also write the above `change_column_default` migration as
+`change_column_default :products, :approved, false`, but unlike the previous
+example, this would make your migration irreversible.
 
 ### Column Modifiers
 
@@ -475,11 +475,13 @@ column names can not be derived from the table names, you can use the
 `:column` and `:primary_key` options.
 
 Rails will generate a name for every foreign key starting with
-`fk_rails_` followed by 10 random characters.
+`fk_rails_` followed by 10 characters which are deterministically
+generated from the `from_table` and `column`.
 There is a `:name` option to specify a different name if needed.
 
 NOTE: Active Record only supports single column foreign keys. `execute` and
-`structure.sql` are required to use composite foreign keys.
+`structure.sql` are required to use composite foreign keys. See
+[Schema Dumping and You](#schema-dumping-and-you).
 
 Removing a foreign key is easy as well:
 
@@ -500,7 +502,7 @@ If the helpers provided by Active Record aren't enough you can use the `execute`
 method to execute arbitrary SQL:
 
 ```ruby
-Product.connection.execute('UPDATE `products` SET `price`=`free` WHERE 1')
+Product.connection.execute("UPDATE products SET price = 'free' WHERE 1=1")
 ```
 
 For more details and examples of individual methods, check the API documentation.
@@ -520,24 +522,39 @@ majority of cases, where Active Record knows how to reverse the migration
 automatically. Currently, the `change` method supports only these migration
 definitions:
 
-* `add_column`
-* `add_index`
-* `add_reference`
-* `add_timestamps`
-* `add_foreign_key`
-* `create_table`
-* `create_join_table`
-* `drop_table` (must supply a block)
-* `drop_join_table` (must supply a block)
-* `remove_timestamps`
-* `rename_column`
-* `rename_index`
-* `remove_reference`
-* `rename_table`
+* add_column
+* add_foreign_key
+* add_index
+* add_reference
+* add_timestamps
+* change_column_default (must supply a :from and :to option)
+* change_column_null
+* create_join_table
+* create_table
+* disable_extension
+* drop_join_table
+* drop_table (must supply a block)
+* enable_extension
+* remove_column (must supply a type)
+* remove_foreign_key (must supply a second table)
+* remove_index
+* remove_reference
+* remove_timestamps
+* rename_column
+* rename_index
+* rename_table
 
 `change_table` is also reversible, as long as the block does not call `change`,
 `change_default` or `remove`.
 
+`remove_column` is reversible if you supply the column type as the third
+argument. Provide the original column options too, otherwise Rails can't
+recreate the column exactly when rolling back:
+
+```ruby
+remove_column :posts, :slug, :string, null: false, default: '', index: true
+```
+
 If you're going to need to use any other methods, you should use `reversible`
 or write the `up` and `down` methods instead of using the `change` method.
 
@@ -545,7 +562,7 @@ or write the `up` and `down` methods instead of using the `change` method.
 
 Complex migrations may require processing that Active Record doesn't know how
 to reverse. You can use `reversible` to specify what to do when running a
-migration what else to do when reverting it. For example:
+migration and what else to do when reverting it. For example:
 
 ```ruby
 class ExampleMigration < ActiveRecord::Migration
@@ -597,7 +614,7 @@ schema, and the `down` method of your migration should revert the
 transformations done by the `up` method. In other words, the database schema
 should be unchanged if you do an `up` followed by a `down`. For example, if you
 create a table in the `up` method, you should drop it in the `down` method. It
-is wise to reverse the transformations in precisely the reverse order they were
+is wise to perform the transformations in precisely the reverse order they were
 made in the `up` method. The example in the `reversible` section is equivalent to:
 
 ```ruby
@@ -642,7 +659,7 @@ can't be done.
 You can use Active Record's ability to rollback migrations using the `revert` method:
 
 ```ruby
-require_relative '2012121212_example_migration'
+require_relative '20121212123456_example_migration'
 
 class FixupExampleMigration < ActiveRecord::Migration
   def change
@@ -695,6 +712,10 @@ of `create_table` and `reversible`, replacing `create_table`
 by `drop_table`, and finally replacing `up` by `down` and vice-versa.
 This is all taken care of by `revert`.
 
+NOTE: If you want to add check constraints like in the examples above,
+you will have to use `structure.sql` as dump method. See
+[Schema Dumping and You](#schema-dumping-and-you).
+
 Running Migrations
 ------------------
 
@@ -768,7 +789,7 @@ The `rake db:reset` task will drop the database and set it up again. This is
 functionally equivalent to `rake db:drop db:setup`.
 
 NOTE: This is not the same as running all the migrations. It will only use the
-contents of the current `schema.rb` file. If a migration can't be rolled back,
+contents of the current `db/schema.rb` or `db/structure.sql` file. If a migration can't be rolled back,
 `rake db:reset` may not help you. To find out more about dumping the schema see
 [Schema Dumping and You](#schema-dumping-and-you) section.
 
@@ -943,10 +964,10 @@ that Active Record supports. This could be very useful if you were to
 distribute an application that is able to run against multiple databases.
 
 There is however a trade-off: `db/schema.rb` cannot express database specific
-items such as triggers, or stored procedures. While in a migration you can
-execute custom SQL statements, the schema dumper cannot reconstitute those
-statements from the database. If you are using features like this, then you
-should set the schema format to `:sql`.
+items such as triggers, stored procedures or check constraints. While in a
+migration you can execute custom SQL statements, the schema dumper cannot
+reconstitute those statements from the database. If you are using features like
+this, then you should set the schema format to `:sql`.
 
 Instead of using Active Record's schema dumper, the database's structure will
 be dumped using a tool specific to the database (via the `db:structure:dump`
@@ -990,7 +1011,10 @@ such features, the `execute` method can be used to execute arbitrary SQL.
 Migrations and Seed Data
 ------------------------
 
-Some people use migrations to add data to the database:
+The main purpose of Rails' migration feature is to issue commands that modify the 
+schema using a consistent process. Migrations can also be used 
+to add or modify data. This is useful in an existing database that can't be destroyed 
+and recreated, such as a production database. 
 
 ```ruby
 class AddInitialProducts < ActiveRecord::Migration
@@ -1006,9 +1030,11 @@ class AddInitialProducts < ActiveRecord::Migration
 end
 ```
 
-However, Rails has a 'seeds' feature that should be used for seeding a database
-with initial data. It's a really simple feature: just fill up `db/seeds.rb`
-with some Ruby code, and run `rake db:seed`:
+To add initial data after a database is created, Rails has a built-in 
+'seeds' feature that makes the process quick and easy. This is especially 
+useful when reloading the database frequently in development and test environments. 
+It's easy to get started with this feature: just fill up `db/seeds.rb` with some 
+Ruby code, and run `rake db:seed`:
 
 ```ruby
 5.times do |i|
diff --git a/guides/source/active_record_postgresql.md b/guides/source/active_record_postgresql.md
index 4d9c1776f4..742db7be32 100644
--- a/guides/source/active_record_postgresql.md
+++ b/guides/source/active_record_postgresql.md
@@ -29,8 +29,8 @@ that are supported by the PostgreSQL adapter.
 
 ### Bytea
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/datatype-binary.html)
-* [functions and operators](http://www.postgresql.org/docs/9.3/static/functions-binarystring.html)
+* [type definition](http://www.postgresql.org/docs/current/static/datatype-binary.html)
+* [functions and operators](http://www.postgresql.org/docs/current/static/functions-binarystring.html)
 
 ```ruby
 # db/migrate/20140207133952_create_documents.rb
@@ -49,8 +49,8 @@ Document.create payload: data
 
 ### Array
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/arrays.html)
-* [functions and operators](http://www.postgresql.org/docs/9.3/static/functions-array.html)
+* [type definition](http://www.postgresql.org/docs/current/static/arrays.html)
+* [functions and operators](http://www.postgresql.org/docs/current/static/functions-array.html)
 
 ```ruby
 # db/migrate/20140207133952_create_books.rb
@@ -83,9 +83,9 @@ Book.where("array_length(ratings, 1) >= 3")
 
 ### Hstore
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/hstore.html)
+* [type definition](http://www.postgresql.org/docs/current/static/hstore.html)
 
-NOTE: you need to enable the `hstore` extension to use hstore.
+NOTE: You need to enable the `hstore` extension to use hstore.
 
 ```ruby
 # db/migrate/20131009135255_create_profiles.rb
@@ -112,8 +112,8 @@ profile.save!
 
 ### JSON
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/datatype-json.html)
-* [functions and operators](http://www.postgresql.org/docs/9.3/static/functions-json.html)
+* [type definition](http://www.postgresql.org/docs/current/static/datatype-json.html)
+* [functions and operators](http://www.postgresql.org/docs/current/static/functions-json.html)
 
 ```ruby
 # db/migrate/20131220144913_create_events.rb
@@ -138,10 +138,10 @@ Event.where("payload->>'kind' = ?", "user_renamed")
 
 ### Range Types
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/rangetypes.html)
-* [functions and operators](http://www.postgresql.org/docs/9.3/static/functions-range.html)
+* [type definition](http://www.postgresql.org/docs/current/static/rangetypes.html)
+* [functions and operators](http://www.postgresql.org/docs/current/static/functions-range.html)
 
-This type is mapped to Ruby [`Range`](http://www.ruby-doc.org/core-2.1.1/Range.html) objects.
+This type is mapped to Ruby [`Range`](http://www.ruby-doc.org/core-2.2.2/Range.html) objects.
 
 ```ruby
 # db/migrate/20130923065404_create_events.rb
@@ -173,7 +173,7 @@ event.ends_at # => Thu, 13 Feb 2014
 
 ### Composite Types
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/rowtypes.html)
+* [type definition](http://www.postgresql.org/docs/current/static/rowtypes.html)
 
 Currently there is no special support for composite types. They are mapped to
 normal text columns:
@@ -213,18 +213,29 @@ contact.save!
 
 ### Enumerated Types
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/datatype-enum.html)
+* [type definition](http://www.postgresql.org/docs/current/static/datatype-enum.html)
 
 Currently there is no special support for enumerated types. They are mapped as
 normal text columns:
 
 ```ruby
 # db/migrate/20131220144913_create_articles.rb
-execute <<-SQL
-  CREATE TYPE article_status AS ENUM ('draft', 'published');
-SQL
-create_table :articles do |t|
-  t.column :status, :article_status
+def up
+  execute <<-SQL
+    CREATE TYPE article_status AS ENUM ('draft', 'published');
+  SQL
+  create_table :articles do |t|
+    t.column :status, :article_status
+  end
+end
+
+# NOTE: It's important to drop table before dropping enum.
+def down
+  drop_table :articles
+
+  execute <<-SQL
+    DROP TYPE article_status;
+  SQL
 end
 
 # app/models/article.rb
@@ -240,16 +251,46 @@ article.status = "published"
 article.save!
 ```
 
+To add a new value before/after existing one you should use [ALTER TYPE](http://www.postgresql.org/docs/current/static/sql-altertype.html):
+
+```ruby
+# db/migrate/20150720144913_add_new_state_to_articles.rb
+# NOTE: ALTER TYPE ... ADD VALUE cannot be executed inside of a transaction block so here we are using disable_ddl_transaction!
+disable_ddl_transaction!
+
+def up
+  execute <<-SQL
+    ALTER TYPE article_status ADD VALUE IF NOT EXISTS 'archived' AFTER 'published';
+  SQL
+end
+```
+
+NOTE: ENUM values can't be dropped currently. You can read why [here](http://www.postgresql.org/message-id/29F36C7C98AB09499B1A209D48EAA615B7653DBC8A@mail2a.alliedtesting.com).
+
+Hint: to show all the values of the all enums you have, you should call this query in `bin/rails db` or `psql` console:
+
+```sql
+SELECT n.nspname AS enum_schema,
+       t.typname AS enum_name,
+       e.enumlabel AS enum_value
+  FROM pg_type t
+      JOIN pg_enum e ON t.oid = e.enumtypid
+      JOIN pg_catalog.pg_namespace n ON n.oid = t.typnamespace
+```
+
 ### UUID
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/datatype-uuid.html)
-* [generator functions](http://www.postgresql.org/docs/9.3/static/uuid-ossp.html)
+* [type definition](http://www.postgresql.org/docs/current/static/datatype-uuid.html)
+* [pgcrypto generator function](http://www.postgresql.org/docs/current/static/pgcrypto.html#AEN159361)
+* [uuid-ossp generator functions](http://www.postgresql.org/docs/current/static/uuid-ossp.html)
 
+NOTE: You need to enable the `pgcrypto` (only PostgreSQL >= 9.4) or `uuid-ossp`
+extension to use uuid.
 
 ```ruby
 # db/migrate/20131220144913_create_revisions.rb
 create_table :revisions do |t|
-  t.column :identifier, :uuid
+  t.uuid :identifier
 end
 
 # app/models/revision.rb
@@ -263,10 +304,35 @@ revision = Revision.first
 revision.identifier # => "a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11"
 ```
 
+You can use `uuid` type to define references in migrations:
+
+```ruby
+# db/migrate/20150418012400_create_blog.rb
+enable_extension 'pgcrypto' unless extension_enabled?('pgcrypto')
+create_table :posts, id: :uuid, default: 'gen_random_uuid()'
+
+create_table :comments, id: :uuid, default: 'gen_random_uuid()' do |t|
+  # t.belongs_to :post, type: :uuid
+  t.references :post, type: :uuid
+end
+
+# app/models/post.rb
+class Post < ActiveRecord::Base
+  has_many :comments
+end
+
+# app/models/comment.rb
+class Comment < ActiveRecord::Base
+  belongs_to :post
+end
+```
+
+See [this section](#uuid-primary-keys) for more details on using UUIDs as primary key.
+
 ### Bit String Types
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/datatype-bit.html)
-* [functions and operators](http://www.postgresql.org/docs/9.3/static/functions-bitstring.html)
+* [type definition](http://www.postgresql.org/docs/current/static/datatype-bit.html)
+* [functions and operators](http://www.postgresql.org/docs/current/static/functions-bitstring.html)
 
 ```ruby
 # db/migrate/20131220144913_create_users.rb
@@ -289,10 +355,10 @@ user.save!
 
 ### Network Address Types
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/datatype-net-types.html)
+* [type definition](http://www.postgresql.org/docs/current/static/datatype-net-types.html)
 
 The types `inet` and `cidr` are mapped to Ruby
-[`IPAddr`](http://www.ruby-doc.org/stdlib-2.1.1/libdoc/ipaddr/rdoc/IPAddr.html)
+[`IPAddr`](http://www.ruby-doc.org/stdlib-2.2.2/libdoc/ipaddr/rdoc/IPAddr.html)
 objects. The `macaddr` type is mapped to normal text.
 
 ```ruby
@@ -324,7 +390,7 @@ macbook.address
 
 ### Geometric Types
 
-* [type definition](http://www.postgresql.org/docs/9.3/static/datatype-geometric.html)
+* [type definition](http://www.postgresql.org/docs/current/static/datatype-geometric.html)
 
 All geometric types, with the exception of `points` are mapped to normal text.
 A point is casted to an array containing `x` and `y` coordinates.
@@ -333,12 +399,13 @@ A point is casted to an array containing `x` and `y` coordinates.
 UUID Primary Keys
 -----------------
 
-NOTE: you need to enable the `uuid-ossp` extension to generate UUIDs.
+NOTE: You need to enable the `pgcrypto` (only PostgreSQL >= 9.4) or `uuid-ossp`
+extension to generate random UUIDs.
 
 ```ruby
 # db/migrate/20131220144913_create_devices.rb
-enable_extension 'uuid-ossp' unless extension_enabled?('uuid-ossp')
-create_table :devices, id: :uuid, default: 'uuid_generate_v4()' do |t|
+enable_extension 'pgcrypto' unless extension_enabled?('pgcrypto')
+create_table :devices, id: :uuid, default: 'gen_random_uuid()' do |t|
   t.string :kind
 end
 
@@ -351,6 +418,9 @@ device = Device.create
 device.id # => "814865cd-5a1d-4771-9306-4268f188fe9e"
 ```
 
+NOTE: `uuid_generate_v4()` (from `uuid-ossp`) is assumed if no `:default` option was
+passed to `create_table`.
+
 Full Text Search
 ----------------
 
@@ -378,7 +448,7 @@ Document.where("to_tsvector('english', title || ' ' || body) @@ to_tsquery(?)",
 Database Views
 --------------
 
-* [view creation](http://www.postgresql.org/docs/9.3/static/sql-createview.html)
+* [view creation](http://www.postgresql.org/docs/current/static/sql-createview.html)
 
 Imagine you need to work with a legacy database containing the following table:
 
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index 434b308170..8ea0f383c0 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -10,7 +10,7 @@ After reading this guide, you will know:
 * How to find records using a variety of methods and conditions.
 * How to specify the order, retrieved attributes, grouping, and other properties of the found records.
 * How to use eager loading to reduce the number of database queries needed for data retrieval.
-* How to use dynamic finders methods.
+* How to use dynamic finder methods.
 * How to use method chaining to use multiple ActiveRecord methods together.
 * How to check for the existence of particular records.
 * How to perform various calculations on Active Record models.
@@ -317,7 +317,7 @@ end
 
 The `find_each` method accepts most of the options allowed by the regular `find` method, except for `:order` and `:limit`, which are reserved for internal use by `find_each`.
 
-Two additional options, `:batch_size` and `:start`, are available as well.
+Three additional options, `:batch_size`, `:begin_at` and `:end_at`, are available as well.
 
 **`:batch_size`**
 
@@ -329,19 +329,34 @@ User.find_each(batch_size: 5000) do |user|
 end
 ```
 
-**`:start`**
+**`:begin_at`**
 
-By default, records are fetched in ascending order of the primary key, which must be an integer. The `:start` option allows you to configure the first ID of the sequence whenever the lowest ID is not the one you need. This would be useful, for example, if you wanted to resume an interrupted batch process, provided you saved the last processed ID as a checkpoint.
+By default, records are fetched in ascending order of the primary key, which must be an integer. The `:begin_at` option allows you to configure the first ID of the sequence whenever the lowest ID is not the one you need. This would be useful, for example, if you wanted to resume an interrupted batch process, provided you saved the last processed ID as a checkpoint.
 
 For example, to send newsletters only to users with the primary key starting from 2000, and to retrieve them in batches of 5000:
 
 ```ruby
-User.find_each(start: 2000, batch_size: 5000) do |user|
+User.find_each(begin_at: 2000, batch_size: 5000) do |user|
   NewsMailer.weekly(user).deliver_now
 end
 ```
 
-Another example would be if you wanted multiple workers handling the same processing queue. You could have each worker handle 10000 records by setting the appropriate `:start` option on each worker.
+**`:end_at`**
+
+Similar to the `:begin_at` option, `:end_at` allows you to configure the last ID of the sequence whenever the highest ID is not the one you need.
+This would be useful, for example, if you wanted to run a batch process, using a subset of records based on `:begin_at` and `:end_at`
+
+For example, to send newsletters only to users with the primary key starting from 2000 up to 10000 and to retrieve them in batches of 5000:
+
+```ruby
+User.find_each(begin_at: 2000, end_at: 10000, batch_size: 5000) do |user|
+  NewsMailer.weekly(user).deliver_now
+end
+```
+
+Another example would be if you wanted multiple workers handling the same
+processing queue. You could have each worker handle 10000 records by setting the
+appropriate `:begin_at` and `:end_at` options on each worker.
 
 #### `find_in_batches`
 
@@ -356,7 +371,7 @@ end
 
 ##### Options for `find_in_batches`
 
-The `find_in_batches` method accepts the same `:batch_size` and `:start` options as `find_each`.
+The `find_in_batches` method accepts the same `:batch_size`, `:begin_at` and `:end_at` options as `find_each`.
 
 Conditions
 ----------
@@ -377,7 +392,7 @@ Now what if that number could vary, say as an argument from somewhere? The find
 Client.where("orders_count = ?", params[:orders])
 ```
 
-Active Record will go through the first element in the conditions value and any additional elements will replace the question marks `(?)` in the first element.
+Active Record will take the first argument as the conditions string and any additional arguments will replace the question marks `(?)` in it.
 
 If you want to specify multiple conditions:
 
@@ -405,7 +420,7 @@ TIP: For more information on the dangers of SQL injection, see the [Ruby on Rail
 
 #### Placeholder Conditions
 
-Similar to the `(?)` replacement style of params, you can also specify keys/values hash in your array conditions:
+Similar to the `(?)` replacement style of params, you can also specify keys in your conditions string along with a corresponding keys/values hash:
 
 ```ruby
 Client.where("created_at >= :start_date AND created_at <= :end_date",
@@ -416,7 +431,7 @@ This makes for clearer readability if you have a large number of variable condit
 
 ### Hash Conditions
 
-Active Record also allows you to pass in hash conditions which can increase the readability of your conditions syntax. With hash conditions, you pass in a hash with keys of the fields you want conditionalised and the values of how you want to conditionalise them:
+Active Record also allows you to pass in hash conditions which can increase the readability of your conditions syntax. With hash conditions, you pass in a hash with keys of the fields you want qualified and the values of how you want to qualify them:
 
 NOTE: Only equality, range and subset checking are possible with Hash conditions.
 
@@ -516,7 +531,7 @@ Client.order("orders_count ASC, created_at DESC")
 Client.order("orders_count ASC", "created_at DESC")
 ```
 
-If you want to call `order` multiple times e.g. in different context, new order will append previous one
+If you want to call `order` multiple times, subsequent orders will be appended to the first:
 
 ```ruby
 Client.order("orders_count ASC").order("created_at DESC")
@@ -604,9 +619,9 @@ SELECT * FROM clients LIMIT 5 OFFSET 30
 Group
 -----
 
-To apply a `GROUP BY` clause to the SQL fired by the finder, you can specify the `group` method on the find.
+To apply a `GROUP BY` clause to the SQL fired by the finder, you can use the `group` method.
 
-For example, if you want to find a collection of the dates orders were created on:
+For example, if you want to find a collection of the dates on which orders were created:
 
 ```ruby
 Order.select("date(created_at) as ordered_date, sum(price) as total_price").group("date(created_at)")
@@ -624,7 +639,7 @@ GROUP BY date(created_at)
 
 ### Total of grouped items
 
-To get the total of grouped items on a single query call `count` after the `group`.
+To get the total of grouped items on a single query, call `count` after the `group`.
 
 ```ruby
 Order.group(:status).count
@@ -642,7 +657,7 @@ GROUP BY status
 Having
 ------
 
-SQL uses the `HAVING` clause to specify conditions on the `GROUP BY` fields. You can add the `HAVING` clause to the SQL fired by the `Model.find` by adding the `:having` option to the find.
+SQL uses the `HAVING` clause to specify conditions on the `GROUP BY` fields. You can add the `HAVING` clause to the SQL fired by the `Model.find` by adding the `having` method to the find.
 
 For example:
 
@@ -660,7 +675,7 @@ GROUP BY date(created_at)
 HAVING sum(price) > 100
 ```
 
-This will return single order objects for each day, but only those that are ordered more than $100 in a day.
+This returns the date and total price for each order object, grouped by the day they were ordered and where the price is more than $100.
 
 Overriding Conditions
 ---------------------
@@ -690,8 +705,7 @@ Article.where(id: 10, trashed: false).unscope(where: :id)
 # SELECT "articles".* FROM "articles" WHERE trashed = 0
 ```
 
-A relation which has used `unscope` will affect any relation it is
-merged in to:
+A relation which has used `unscope` will affect any relation into which it is merged:
 
 ```ruby
 Article.order('id asc').merge(Article.unscope(:order))
@@ -735,7 +749,7 @@ SELECT * FROM articles WHERE id = 10
 SELECT * FROM comments WHERE article_id = 10 ORDER BY name
 ```
 
-In case the `reorder` clause is not used, the SQL executed would be:
+In the case where the `reorder` clause is not used, the SQL executed would be:
 
 ```sql
 SELECT * FROM articles WHERE id = 10
@@ -824,7 +838,7 @@ end
 Readonly Objects
 ----------------
 
-Active Record provides `readonly` method on a relation to explicitly disallow modification of any of the returned objects. Any attempt to alter a readonly record will not succeed, raising an `ActiveRecord::ReadOnlyRecord` exception.
+Active Record provides the `readonly` method on a relation to explicitly disallow modification of any of the returned objects. Any attempt to alter a readonly record will not succeed, raising an `ActiveRecord::ReadOnlyRecord` exception.
 
 ```ruby
 client = Client.readonly.first
@@ -885,7 +899,7 @@ For example:
 Item.transaction do
   i = Item.lock.first
   i.name = 'Jones'
-  i.save
+  i.save!
 end
 ```
 
@@ -1037,7 +1051,7 @@ SELECT categories.* FROM categories
 
 ### Specifying Conditions on the Joined Tables
 
-You can specify conditions on the joined tables using the regular [Array](#array-conditions) and [String](#pure-string-conditions) conditions. [Hash conditions](#hash-conditions) provides a special syntax for specifying conditions for the joined tables:
+You can specify conditions on the joined tables using the regular [Array](#array-conditions) and [String](#pure-string-conditions) conditions. [Hash conditions](#hash-conditions) provide a special syntax for specifying conditions for the joined tables:
 
 ```ruby
 time_range = (Time.now.midnight - 1.day)..Time.now.midnight
@@ -1076,7 +1090,7 @@ This code looks fine at the first sight. But the problem lies within the total n
 
 Active Record lets you specify in advance all the associations that are going to be loaded. This is possible by specifying the `includes` method of the `Model.find` call. With `includes`, Active Record ensures that all of the specified associations are loaded using the minimum possible number of queries.
 
-Revisiting the above case, we could rewrite `Client.limit(10)` to use eager load addresses:
+Revisiting the above case, we could rewrite `Client.limit(10)` to eager load addresses:
 
 ```ruby
 clients = Client.includes(:address).limit(10)
@@ -1134,7 +1148,7 @@ This would generate a query which contains a `LEFT OUTER JOIN` whereas the
 If there was no `where` condition, this would generate the normal set of two queries.
 
 NOTE: Using `where` like this will only work when you pass it a Hash. For
-SQL-fragments you need use `references` to force joined tables:
+SQL-fragments you need to use `references` to force joined tables:
 
 ```ruby
 Article.includes(:comments).where("comments.visible = true").references(:comments)
@@ -1253,6 +1267,18 @@ class Client < ActiveRecord::Base
 end
 ```
 
+NOTE: The `default_scope` is also applied while creating/building a record.
+It is not applied while updating a record. E.g.:
+
+```ruby
+class Client < ActiveRecord::Base
+  default_scope { where(active: true) }
+end
+
+Client.new          # => #<Client id: nil, active: true>
+Client.unscoped.new # => #<Client id: nil, active: nil>
+```
+
 ### Merging of scopes
 
 Just like `where` clauses scopes are merged using `AND` conditions.
@@ -1275,7 +1301,7 @@ User.active.where(state: 'finished')
 # SELECT "users".* FROM "users" WHERE "users"."state" = 'active' AND "users"."state" = 'finished'
 ```
 
-If we do want the `last where clause` to win then `Relation#merge` can
+If we do want the last `where` clause to win then `Relation#merge` can
 be used.
 
 ```ruby
@@ -1330,7 +1356,7 @@ Client.unscoped {
 Dynamic Finders
 ---------------
 
-For every field (also known as an attribute) you define in your table, Active Record provides a finder method. If you have a field called `first_name` on your `Client` model for example, you get `find_by_first_name` for free from Active Record. If you have a `locked` field on the `Client` model, you also get `find_by_locked` and methods.
+For every field (also known as an attribute) you define in your table, Active Record provides a finder method. If you have a field called `first_name` on your `Client` model for example, you get `find_by_first_name` for free from Active Record. If you have a `locked` field on the `Client` model, you also get `find_by_locked` method.
 
 You can specify an exclamation point (`!`) on the end of the dynamic finders to get them to raise an `ActiveRecord::RecordNotFound` error if they do not return any records, like `Client.find_by_name!("Ryan")`
 
@@ -1390,8 +1416,9 @@ WHERE people.name = 'John'
 LIMIT 1
 ```
 
-NOTE: Remember that, if `find_by` returns more than one registry, it will take
-just the first and ignore the others. Note the `LIMIT 1` statement above.
+NOTE: Note that if a query matches multiple records, `find_by` will
+fetch only the first one and ignore the others (see the `LIMIT 1`
+statement above).
 
 Find or Build a New Object
 --------------------------
@@ -1400,7 +1427,7 @@ It's common that you need to find a record or create it if it doesn't exist. You
 
 ### `find_or_create_by`
 
-The `find_or_create_by` method checks whether a record with the attributes exists. If it doesn't, then `create` is called. Let's see an example.
+The `find_or_create_by` method checks whether a record with the specified attributes exists. If it doesn't, then `create` is called. Let's see an example.
 
 Suppose you want to find a client named 'Andy', and if there's none, create one. You can do so by running:
 
@@ -1773,8 +1800,9 @@ EXPLAIN for: SELECT `users`.* FROM `users` INNER JOIN `articles` ON `articles`.`
 
 under MySQL.
 
-Active Record performs a pretty printing that emulates the one of the database
-shells. So, the same query running with the PostgreSQL adapter would yield instead
+Active Record performs a pretty printing that emulates that of the
+corresponding database shell. So, the same query running with the
+PostgreSQL adapter would yield instead
 
 ```
 EXPLAIN for: SELECT "users".* FROM "users" INNER JOIN "articles" ON "articles"."user_id" = "users"."id" WHERE "users"."id" = 1
@@ -1839,6 +1867,6 @@ following pointers may be helpful:
 
 * SQLite3: [EXPLAIN QUERY PLAN](http://www.sqlite.org/eqp.html)
 
-* MySQL: [EXPLAIN Output Format](http://dev.mysql.com/doc/refman/5.6/en/explain-output.html)
+* MySQL: [EXPLAIN Output Format](http://dev.mysql.com/doc/refman/5.7/en/explain-output.html)
 
 * PostgreSQL: [Using EXPLAIN](http://www.postgresql.org/docs/current/static/using-explain.html)
diff --git a/guides/source/active_record_validations.md b/guides/source/active_record_validations.md
index c9af70934a..dd4d9f55fa 100644
--- a/guides/source/active_record_validations.md
+++ b/guides/source/active_record_validations.md
@@ -47,7 +47,7 @@ built-in helpers for common needs, and allows you to create your own validation
 methods as well.
 
 There are several other ways to validate data before it is saved into your
-database, including native database constraints, client-side validations,
+database, including native database constraints, client-side validations and
 controller-level validations. Here's a summary of the pros and cons:
 
 * Database constraints and/or stored procedures make the validation mechanisms
@@ -122,7 +122,7 @@ database only if the object is valid:
 * `update!`
 
 The bang versions (e.g. `save!`) raise an exception if the record is invalid.
-The non-bang versions don't, `save` and `update` return `false`,
+The non-bang versions don't: `save` and `update` return `false`, and
 `create` just returns the object.
 
 ### Skipping Validations
@@ -143,14 +143,16 @@ database regardless of its validity. They should be used with caution.
 * `update_counters`
 
 Note that `save` also has the ability to skip validations if passed `validate:
-false` as argument. This technique should be used with caution.
+false` as an argument. This technique should be used with caution.
 
 * `save(validate: false)`
 
 ### `valid?` and `invalid?`
 
-To verify whether or not an object is valid, Rails uses the `valid?` method.
-You can also use this method on your own. `valid?` triggers your validations
+Before saving an ActiveRecord object, Rails runs your validations.
+If these validations produce any errors, Rails does not save the object.
+
+You can also run these validations on your own. `valid?` triggers your validations
 and returns true if no errors were found in the object, and false otherwise.
 As you saw above:
 
@@ -168,8 +170,9 @@ through the `errors.messages` instance method, which returns a collection of err
 By definition, an object is valid if this collection is empty after running
 validations.
 
-Note that an object instantiated with `new` will not report errors even if it's
-technically invalid, because validations are not run when using `new`.
+Note that an object instantiated with `new` will not report errors
+even if it's technically invalid, because validations are automatically run
+only when the object is saved, such as with the `create` or `save` methods.
 
 ```ruby
 class Person < ActiveRecord::Base
@@ -227,8 +230,26 @@ end
 ```
 
 We'll cover validation errors in greater depth in the [Working with Validation
-Errors](#working-with-validation-errors) section. For now, let's turn to the
-built-in validation helpers that Rails provides by default.
+Errors](#working-with-validation-errors) section.
+
+### `errors.details`
+
+To check which validations failed on an invalid attribute, you can use
+`errors.details[:attribute]`. It returns an array of hashes with an `:error`
+key to get the symbol of the validator:
+
+```ruby
+class Person < ActiveRecord::Base
+  validates :name, presence: true
+end
+
+>> person = Person.new
+>> person.valid?
+>> person.errors.details[:name] # => [{error: :blank}]
+```
+
+Using `details` with custom validators is covered in the [Working with
+Validation Errors](#working-with-validation-errors) section.
 
 Validation Helpers
 ------------------
@@ -254,10 +275,14 @@ available helpers.
 
 This method validates that a checkbox on the user interface was checked when a
 form was submitted. This is typically used when the user needs to agree to your
-application's terms of service, confirm reading some text, or any similar
-concept. This validation is very specific to web applications and this
-'acceptance' does not need to be recorded anywhere in your database (if you
-don't have a field for it, the helper will just create a virtual attribute).
+application's terms of service, confirm that some text is read, or any similar
+concept.
+
+This validation is very specific to web applications and this
+'acceptance' does not need to be recorded anywhere in your database. If you
+don't have a field for it, the helper will just create a virtual attribute. If
+the field does exist in your database, the `accept` option must be set to
+`true` or else the validation will not run.
 
 ```ruby
 class Person < ActiveRecord::Base
@@ -265,6 +290,7 @@ class Person < ActiveRecord::Base
 end
 ```
 
+This check is performed only if `terms_of_service` is not `nil`.
 The default error message for this helper is _"must be accepted"_.
 
 It can receive an `:accept` option, which determines the value that will be
@@ -320,7 +346,7 @@ In your view template you could use something like
 
 This check is performed only if `email_confirmation` is not `nil`. To require
 confirmation, make sure to add a presence check for the confirmation attribute
-(we'll take a look at `presence` later on this guide):
+(we'll take a look at `presence` later on in this guide):
 
 ```ruby
 class Person < ActiveRecord::Base
@@ -329,6 +355,16 @@ class Person < ActiveRecord::Base
 end
 ```
 
+There is also a `:case_sensitive` option that you can use to define whether the
+confirmation constraint will be case sensitive or not. This option defaults to
+true.
+
+```ruby
+class Person < ActiveRecord::Base
+  validates :email, confirmation: { case_sensitive: false }
+end
+```
+
 The default error message for this helper is _"doesn't match confirmation"_.
 
 ### `exclusion`
@@ -452,7 +488,7 @@ point number. To specify that only integral numbers are allowed set
 If you set `:only_integer` to `true`, then it will use the
 
 ```ruby
-/\A[+-]?\d+\Z/
+/\A[+-]?\d+\z/
 ```
 
 regular expression to validate the attribute's value. Otherwise, it will try to
@@ -481,9 +517,9 @@ constraints to acceptable values:
   default error message for this option is _"must be equal to %{count}"_.
 * `:less_than` - Specifies the value must be less than the supplied value. The
   default error message for this option is _"must be less than %{count}"_.
-* `:less_than_or_equal_to` - Specifies the value must be less than or equal the
-  supplied value. The default error message for this option is _"must be less
-  than or equal to %{count}"_.
+* `:less_than_or_equal_to` - Specifies the value must be less than or equal to
+  the supplied value. The default error message for this option is _"must be
+  less than or equal to %{count}"_.
 * `:odd` - Specifies the value must be an odd number if set to true. The
   default error message for this option is _"must be odd"_.
 * `:even` - Specifies the value must be an even number if set to true. The
@@ -533,7 +569,6 @@ Since `false.blank?` is true, if you want to validate the presence of a boolean
 field you should use one of the following validations:
 
 ```ruby
-validates :boolean_field_name, presence: true
 validates :boolean_field_name, inclusion: { in: [true, false] }
 validates :boolean_field_name, exclusion: { in: [nil] }
 ```
@@ -588,9 +623,7 @@ This helper validates that the attribute's value is unique right before the
 object gets saved. It does not create a uniqueness constraint in the database,
 so it may happen that two different database connections create two records
 with the same value for a column that you intend to be unique. To avoid that,
-you must create a unique index on both columns in your database. See
-[the MySQL manual](http://dev.mysql.com/doc/refman/5.6/en/multiple-column-indexes.html)
-for more details about multiple column indexes.
+you must create a unique index on that column in your database.
 
 ```ruby
 class Account < ActiveRecord::Base
@@ -601,7 +634,7 @@ end
 The validation happens by performing an SQL query into the model's table,
 searching for an existing record with the same value in that attribute.
 
-There is a `:scope` option that you can use to specify other attributes that
+There is a `:scope` option that you can use to specify one or more attributes that
 are used to limit the uniqueness check:
 
 ```ruby
@@ -610,6 +643,7 @@ class Holiday < ActiveRecord::Base
     message: "should happen once per year" }
 end
 ```
+Should you wish to create a database constraint to prevent possible violations of a uniqueness validation using the `:scope` option, you must create a unique index on both columns in your database. See [the MySQL manual](http://dev.mysql.com/doc/refman/5.7/en/multiple-column-indexes.html) for more details about multiple column indexes or [the PostgreSQL manual](http://www.postgresql.org/docs/current/static/ddl-constraints.html) for examples of unique constraints that refer to a group of columns.
 
 There is also a `:case_sensitive` option that you can use to define whether the
 uniqueness constraint will be case sensitive or not. This option defaults to
@@ -796,7 +830,7 @@ end
 Person.new.valid?  # => ActiveModel::StrictValidationFailed: Name can't be blank
 ```
 
-There is also an ability to pass custom exception to `:strict` option.
+There is also the ability to pass a custom exception to the `:strict` option.
 
 ```ruby
 class Person < ActiveRecord::Base
@@ -860,7 +894,7 @@ end
 
 ### Grouping Conditional validations
 
-Sometimes it is useful to have multiple validations use one condition, it can
+Sometimes it is useful to have multiple validations use one condition. It can
 be easily achieved using `with_options`.
 
 ```ruby
@@ -872,8 +906,8 @@ class User < ActiveRecord::Base
 end
 ```
 
-All validations inside of `with_options` block will have automatically passed
-the condition `if: :is_admin?`
+All validations inside of the `with_options` block will have automatically
+passed the condition `if: :is_admin?`
 
 ### Combining Validation Conditions
 
@@ -900,8 +934,8 @@ write your own validators or validation methods as you prefer.
 
 ### Custom Validators
 
-Custom validators are classes that extend `ActiveModel::Validator`. These
-classes must implement a `validate` method which takes a record as an argument
+Custom validators are classes that inherit from `ActiveModel::Validator`. These
+classes must implement the `validate` method which takes a record as an argument
 and performs the validation on it. The custom validator is called using the
 `validates_with` method.
 
@@ -948,12 +982,17 @@ own custom validators.
 
 You can also create methods that verify the state of your models and add
 messages to the `errors` collection when they are invalid. You must then
-register these methods by using the `validate` class method, passing in the
-symbols for the validation methods' names.
+register these methods by using the `validate`
+([API](http://api.rubyonrails.org/classes/ActiveModel/Validations/ClassMethods.html#method-i-validate))
+class method, passing in the symbols for the validation methods' names.
 
 You can pass more than one symbol for each class method and the respective
 validations will be run in the same order as they were registered.
 
+The `valid?` method will verify that the errors collection is empty,
+so your custom validation methods should add errors to it when you
+wish validation to fail:
+
 ```ruby
 class Invoice < ActiveRecord::Base
   validate :expiration_date_cannot_be_in_the_past,
@@ -973,9 +1012,10 @@ class Invoice < ActiveRecord::Base
 end
 ```
 
-By default such validations will run every time you call `valid?`. It is also
-possible to control when to run these custom validations by giving an `:on`
-option to the `validate` method, with either: `:create` or `:update`.
+By default, such validations will run every time you call `valid?`
+or save the object. But it is also possible to control when to run these
+custom validations by giving an `:on` option to the `validate` method,
+with either: `:create` or `:update`.
 
 ```ruby
 class Invoice < ActiveRecord::Base
@@ -1038,7 +1078,9 @@ person.errors[:name]
 
 ### `errors.add`
 
-The `add` method lets you manually add messages that are related to particular attributes. You can use the `errors.full_messages` or `errors.to_a` methods to view the messages in the form they might be displayed to a user. Those particular messages get the attribute name prepended (and capitalized). `add` receives the name of the attribute you want to add the message to, and the message itself.
+The `add` method lets you add an error message related to a particular attribute. It takes as arguments the attribute and the error message.
+
+The `errors.full_messages` method (or its equivalent, `errors.to_a`) returns the error messages in a user-friendly format, with the capitalized attribute name prepended to each message, as shown in the examples below.
 
 ```ruby
 class Person < ActiveRecord::Base
@@ -1056,12 +1098,12 @@ person.errors.full_messages
  # => ["Name cannot contain the characters !@#%*()_-+="]
 ```
 
-Another way to do this is using `[]=` setter
+An equivalent to `errors#add` is to use `<<` to append a message to the `errors.messages` array for an attribute:
 
 ```ruby
   class Person < ActiveRecord::Base
     def a_method_used_for_validation_purposes
-      errors[:name] = "cannot contain the characters !@#%*()_-+="
+      errors.messages[:name] << "cannot contain the characters !@#%*()_-+="
     end
   end
 
@@ -1074,6 +1116,43 @@ Another way to do this is using `[]=` setter
    # => ["Name cannot contain the characters !@#%*()_-+="]
 ```
 
+### `errors.details`
+
+You can specify a validator type to the returned error details hash using the
+`errors.add` method.
+
+```ruby
+class Person < ActiveRecord::Base
+  def a_method_used_for_validation_purposes
+    errors.add(:name, :invalid_characters)
+  end
+end
+
+person = Person.create(name: "!@#")
+
+person.errors.details[:name]
+# => [{error: :invalid_characters}]
+```
+
+To improve the error details to contain the unallowed characters set for instance,
+you can pass additional keys to `errors.add`.
+
+```ruby
+class Person < ActiveRecord::Base
+  def a_method_used_for_validation_purposes
+    errors.add(:name, :invalid_characters, not_allowed: "!@#%*()_-+=")
+  end
+end
+
+person = Person.create(name: "!@#")
+
+person.errors.details[:name]
+# => [{error: :invalid_characters, not_allowed: "!@#%*()_-+="}]
+```
+
+All built in Rails validators populate the details hash with the corresponding
+validator type.
+
 ### `errors[:base]`
 
 You can add error messages that are related to the object's state as a whole, instead of being related to a specific attribute. You can use this method when you want to say that the object is invalid, no matter the values of its attributes. Since `errors[:base]` is an array, you can simply add a string to it and it will be used as an error message.
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index 080cc41e87..556b5ede3c 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -172,7 +172,7 @@ NOTE: Defined in `active_support/core_ext/object/duplicable.rb`.
 
 ### `deep_dup`
 
-The `deep_dup` method returns deep copy of a given object. Normally, when you `dup` an object that contains other objects, Ruby does not `dup` them, so it creates a shallow copy of the object. If you have an array with a string, for example, it will look like this:
+The `deep_dup` method returns a deep copy of a given object. Normally, when you `dup` an object that contains other objects, Ruby does not `dup` them, so it creates a shallow copy of the object. If you have an array with a string, for example, it will look like this:
 
 ```ruby
 array     = ['string']
@@ -349,7 +349,7 @@ end
 we get:
 
 ```ruby
-current_user.to_query('user') # => user=357-john-smith
+current_user.to_query('user') # => "user=357-john-smith"
 ```
 
 This method escapes whatever is needed, both for the key and the value:
@@ -453,7 +453,7 @@ NOTE: Defined in `active_support/core_ext/object/instance_variables.rb`.
 
 #### `instance_variable_names`
 
-The method `instance_variable_names` returns an array.  Each name includes the "@" sign.
+The method `instance_variable_names` returns an array. Each name includes the "@" sign.
 
 ```ruby
 class C
@@ -467,7 +467,7 @@ C.new(0, 1).instance_variable_names # => ["@x", "@y"]
 
 NOTE: Defined in `active_support/core_ext/object/instance_variables.rb`.
 
-### Silencing Warnings, Streams, and Exceptions
+### Silencing Warnings and Exceptions
 
 The methods `silence_warnings` and `enable_warnings` change the value of `$VERBOSE` accordingly for the duration of their block, and reset it afterwards:
 
@@ -475,26 +475,10 @@ The methods `silence_warnings` and `enable_warnings` change the value of `$VERBO
 silence_warnings { Object.const_set "RAILS_DEFAULT_LOGGER", logger }
 ```
 
-You can silence any stream while a block runs with `silence_stream`:
+Silencing exceptions is also possible with `suppress`. This method receives an arbitrary number of exception classes. If an exception is raised during the execution of the block and is `kind_of?` any of the arguments, `suppress` captures it and returns silently. Otherwise the exception is not captured:
 
 ```ruby
-silence_stream(STDOUT) do
-  # STDOUT is silent here
-end
-```
-
-The `quietly` method addresses the common use case where you want to silence STDOUT and STDERR, even in subprocesses:
-
-```ruby
-quietly { system 'bundle install' }
-```
-
-For example, the railties test suite uses that one in a few places to prevent command messages from being echoed intermixed with the progress status.
-
-Silencing exceptions is also possible with `suppress`. This method receives an arbitrary number of exception classes. If an exception is raised during the execution of the block and is `kind_of?` any of the arguments, `suppress` captures it and returns silently. Otherwise the exception is reraised:
-
-```ruby
-# If the user is locked the increment is lost, no big deal.
+# If the user is locked, the increment is lost, no big deal.
 suppress(ActiveRecord::StaleObjectError) do
   current_user.increment! :visits
 end
@@ -522,6 +506,8 @@ Extensions to `Module`
 
 ### `alias_method_chain`
 
+**This method is deprecated in favour of using Module#prepend.**
+
 Using plain Ruby you can wrap methods with other methods, that's called _alias chaining_.
 
 For example, let's say you'd like params to be strings in functional tests, as they are in real requests, but still want the convenience of assigning integers and other kind of values. To accomplish that you could wrap `ActionController::TestCase#process` this way in `test/test_helper.rb`:
@@ -566,8 +552,6 @@ ActionController::TestCase.class_eval do
 end
 ```
 
-Rails uses `alias_method_chain` all over the code base. For example validations are added to `ActiveRecord::Base#save` by wrapping the method that way in a separate module specialized in validations.
-
 NOTE: Defined in `active_support/core_ext/module/aliasing.rb`.
 
 ### Attributes
@@ -743,7 +727,7 @@ NOTE: Defined in `active_support/core_ext/module/introspection.rb`.
 
 #### Qualified Constant Names
 
-The standard methods `const_defined?`, `const_get` , and `const_set` accept
+The standard methods `const_defined?`, `const_get`, and `const_set` accept
 bare constant names. Active Support extends this API to be able to pass
 relative qualified constant names.
 
@@ -1253,7 +1237,7 @@ Calling `dup` or `clone` on safe strings yields safe strings.
 The method `remove` will remove all occurrences of the pattern:
 
 ```ruby
-"Hello World".remove(/Hello /) => "World"
+"Hello World".remove(/Hello /) # => "World"
 ```
 
 There's also the destructive version `String#remove!`.
@@ -1881,15 +1865,15 @@ The methods `to_date`, `to_time`, and `to_datetime` are basically convenience wr
 
 ```ruby
 "2010-07-27".to_date              # => Tue, 27 Jul 2010
-"2010-07-27 23:37:00".to_time     # => Tue Jul 27 23:37:00 UTC 2010
+"2010-07-27 23:37:00".to_time     # => 2010-07-27 23:37:00 +0200
 "2010-07-27 23:37:00".to_datetime # => Tue, 27 Jul 2010 23:37:00 +0000
 ```
 
 `to_time` receives an optional argument `:utc` or `:local`, to indicate which time zone you want the time in:
 
 ```ruby
-"2010-07-27 23:42:00".to_time(:utc)   # => Tue Jul 27 23:42:00 UTC 2010
-"2010-07-27 23:42:00".to_time(:local) # => Tue Jul 27 23:42:00 +0200 2010
+"2010-07-27 23:42:00".to_time(:utc)   # => 2010-07-27 23:42:00 UTC
+"2010-07-27 23:42:00".to_time(:local) # => 2010-07-27 23:42:00 +0200
 ```
 
 Default is `:utc`.
@@ -1952,6 +1936,8 @@ as well as adding or subtracting their results from a Time object. For example:
 (4.months + 5.years).from_now
 ```
 
+NOTE: Defined in `active_support/core_ext/numeric/time.rb`
+
 ### Formatting
 
 Enables the formatting of numbers in a variety of ways.
@@ -2087,30 +2073,22 @@ Extensions to `BigDecimal`
 --------------------------
 ### `to_s`
 
-The method `to_s` is aliased to `to_formatted_s`. This provides a convenient way to display a BigDecimal value in floating-point notation:
+The method `to_s` provides a default specifier of "F". This means that a simple call to `to_s` will result in floating point representation instead of engineering notation:
 
 ```ruby
 BigDecimal.new(5.00, 6).to_s  # => "5.0"
 ```
 
-### `to_formatted_s`
-
-Te method `to_formatted_s` provides a default specifier of "F".  This means that a simple call to `to_formatted_s` or `to_s` will result in floating point representation instead of engineering notation:
-
-```ruby
-BigDecimal.new(5.00, 6).to_formatted_s  # => "5.0"
-```
-
 and that symbol specifiers are also supported:
 
 ```ruby
-BigDecimal.new(5.00, 6).to_formatted_s(:db)  # => "5.0"
+BigDecimal.new(5.00, 6).to_s(:db)  # => "5.0"
 ```
 
 Engineering notation is still supported:
 
 ```ruby
-BigDecimal.new(5.00, 6).to_formatted_s("e")  # => "0.5E1"
+BigDecimal.new(5.00, 6).to_s("e")  # => "0.5E1"
 ```
 
 Extensions to `Enumerable`
@@ -2198,6 +2176,27 @@ to_visit << node if visited.exclude?(node)
 
 NOTE: Defined in `active_support/core_ext/enumerable.rb`.
 
+### `without`
+
+The method `without` returns a copy of an enumerable with the specified elements
+removed:
+
+```ruby
+["David", "Rafael", "Aaron", "Todd"].without("Aaron", "Todd") # => ["David", "Rafael"]
+```
+
+NOTE: Defined in `active_support/core_ext/enumerable.rb`.
+
+### `pluck`
+
+The method `pluck` returns an array based on the given key:
+
+```ruby
+[{ name: "David" }, { name: "Rafael" }, { name: "Aaron" }].pluck(:name) # => ["David", "Rafael", "Aaron"]
+```
+
+NOTE: Defined in `active_support/core_ext/enumerable.rb`.
+
 Extensions to `Array`
 ---------------------
 
@@ -2206,14 +2205,14 @@ Extensions to `Array`
 Active Support augments the API of arrays to ease certain ways of accessing them. For example, `to` returns the subarray of elements up to the one at the passed index:
 
 ```ruby
-%w(a b c d).to(2) # => %w(a b c)
+%w(a b c d).to(2) # => ["a", "b", "c"]
 [].to(7)          # => []
 ```
 
 Similarly, `from` returns the tail from the element at the passed index to the end. If the index is greater than the length of the array, it returns an empty array.
 
 ```ruby
-%w(a b c d).from(2)  # => %w(c d)
+%w(a b c d).from(2)  # => ["c", "d"]
 %w(a b c d).from(10) # => []
 [].from(0)           # => []
 ```
@@ -2221,7 +2220,7 @@ Similarly, `from` returns the tail from the element at the passed index to the e
 The methods `second`, `third`, `fourth`, and `fifth` return the corresponding element (`first` is built-in). Thanks to social wisdom and positive constructiveness all around, `forty_two` is also available.
 
 ```ruby
-%w(a b c d).third # => c
+%w(a b c d).third # => "c"
 %w(a b c d).fifth # => nil
 ```
 
@@ -2234,7 +2233,7 @@ NOTE: Defined in `active_support/core_ext/array/access.rb`.
 This method is an alias of `Array#unshift`.
 
 ```ruby
-%w(a b c d).prepend('e')  # => %w(e a b c d)
+%w(a b c d).prepend('e')  # => ["e", "a", "b", "c", "d"]
 [].prepend(10)            # => [10]
 ```
 
@@ -2245,8 +2244,8 @@ NOTE: Defined in `active_support/core_ext/array/prepend_and_append.rb`.
 This method is an alias of `Array#<<`.
 
 ```ruby
-%w(a b c d).append('e')  # => %w(a b c d e)
-[].append([1,2])         # => [[1,2]]
+%w(a b c d).append('e')  # => ["a", "b", "c", "d", "e"]
+[].append([1,2])         # => [[1, 2]]
 ```
 
 NOTE: Defined in `active_support/core_ext/array/prepend_and_append.rb`.
@@ -2433,7 +2432,7 @@ The method `Array.wrap` wraps its argument in an array unless it is already an a
 
 Specifically:
 
-* If the argument is `nil` an empty list is returned.
+* If the argument is `nil` an empty array is returned.
 * Otherwise, if the argument responds to `to_ary` it is invoked, and if the value of `to_ary` is not `nil`, it is returned.
 * Otherwise, an array with the argument as its single element is returned.
 
@@ -2445,9 +2444,9 @@ Array.wrap(0)         # => [0]
 
 This method is similar in purpose to `Kernel#Array`, but there are some differences:
 
-* If the argument responds to `to_ary` the method is invoked. `Kernel#Array` moves on to try `to_a` if the returned value is `nil`, but `Array.wrap` returns `nil` right away.
+* If the argument responds to `to_ary` the method is invoked. `Kernel#Array` moves on to try `to_a` if the returned value is `nil`, but `Array.wrap` returns an array with the argument as its single element right away.
 * If the returned value from `to_ary` is neither `nil` nor an `Array` object, `Kernel#Array` raises an exception, while `Array.wrap` does not, it just returns the value.
-* It does not call `to_a` on the argument, though special-cases `nil` to return an empty array.
+* It does not call `to_a` on the argument, if the argument does not respond to +to_ary+ it returns an array with the argument as its single element.
 
 The last point is particularly worth comparing for some enumerables:
 
@@ -2470,7 +2469,7 @@ NOTE: Defined in `active_support/core_ext/array/wrap.rb`.
 
 ### Duplicating
 
-The method `Array.deep_dup` duplicates itself and all objects inside
+The method `Array#deep_dup` duplicates itself and all objects inside
 recursively with Active Support method `Object#deep_dup`. It works like `Array#map` with sending `deep_dup` method to each object inside.
 
 ```ruby
@@ -2692,7 +2691,7 @@ NOTE: Defined in `active_support/core_ext/hash/deep_merge.rb`.
 
 ### Deep duplicating
 
-The method `Hash.deep_dup` duplicates itself and all keys and values
+The method `Hash#deep_dup` duplicates itself and all keys and values
 inside recursively with Active Support method `Object#deep_dup`. It works like `Enumerator#each_with_object` with sending `deep_dup` method to each pair inside.
 
 ```ruby
@@ -2888,7 +2887,7 @@ The method `transform_values` accepts a block and returns a hash that has applie
 ```
 There's also the bang variant `transform_values!` that applies the block operations to values in the very receiver.
 
-NOTE: Defined in `active_support/core_text/hash/transform_values.rb`.
+NOTE: Defined in `active_support/core_ext/hash/transform_values.rb`.
 
 ### Slicing
 
@@ -3045,53 +3044,6 @@ The method `Range#overlaps?` says whether any two given ranges have non-void int
 
 NOTE: Defined in `active_support/core_ext/range/overlaps.rb`.
 
-Extensions to `Proc`
---------------------
-
-### `bind`
-
-As you surely know Ruby has an `UnboundMethod` class whose instances are methods that belong to the limbo of methods without a self. The method `Module#instance_method` returns an unbound method for example:
-
-```ruby
-Hash.instance_method(:delete) # => #<UnboundMethod: Hash#delete>
-```
-
-An unbound method is not callable as is, you need to bind it first to an object with `bind`:
-
-```ruby
-clear = Hash.instance_method(:clear)
-clear.bind({a: 1}).call # => {}
-```
-
-Active Support defines `Proc#bind` with an analogous purpose:
-
-```ruby
-Proc.new { size }.bind([]).call # => 0
-```
-
-As you see that's callable and bound to the argument, the return value is indeed a `Method`.
-
-NOTE: To do so `Proc#bind` actually creates a method under the hood. If you ever see a method with a weird name like `__bind_1256598120_237302` in a stack trace you know now where it comes from.
-
-Action Pack uses this trick in `rescue_from` for example, which accepts the name of a method and also a proc as callbacks for a given rescued exception. It has to call them in either case, so a bound method is returned by `handler_for_rescue`, thus simplifying the code in the caller:
-
-```ruby
-def handler_for_rescue(exception)
-  _, rescuer = Array(rescue_handlers).reverse.detect do |klass_name, handler|
-    ...
-  end
-
-  case rescuer
-  when Symbol
-    method(rescuer)
-  when Proc
-    rescuer.bind(self)
-  end
-end
-```
-
-NOTE: Defined in `active_support/core_ext/proc.rb`.
-
 Extensions to `Date`
 --------------------
 
@@ -3813,50 +3765,6 @@ WARNING. If the argument is an `IO` it needs to respond to `rewind` to be able t
 
 NOTE: Defined in `active_support/core_ext/marshal.rb`.
 
-Extensions to `Logger`
-----------------------
-
-### `around_[level]`
-
-Takes two arguments, a `before_message` and `after_message` and calls the current level method on the `Logger` instance, passing in the `before_message`, then the specified message, then the `after_message`:
-
-```ruby
-logger = Logger.new("log/development.log")
-logger.around_info("before", "after") { |logger| logger.info("during") }
-```
-
-### `silence`
-
-Silences every log level lesser to the specified one for the duration of the given block. Log level orders are: debug, info, error and fatal.
-
-```ruby
-logger = Logger.new("log/development.log")
-logger.silence(Logger::INFO) do
-  logger.debug("In space, no one can hear you scream.")
-  logger.info("Scream all you want, small mailman!")
-end
-```
-
-### `datetime_format=`
-
-Modifies the datetime format output by the formatter class associated with this logger. If the formatter class does not have a `datetime_format` method then this is ignored.
-
-```ruby
-class Logger::FormatWithTime < Logger::Formatter
-  cattr_accessor(:datetime_format) { "%Y%m%d%H%m%S" }
-
-  def self.call(severity, timestamp, progname, msg)
-    "#{timestamp.strftime(datetime_format)} -- #{String === msg ? msg : msg.inspect}\n"
-  end
-end
-
-logger = Logger.new("log/development.log")
-logger.formatter = Logger::FormatWithTime
-logger.info("<- is the current time")
-```
-
-NOTE: Defined in `active_support/core_ext/logger.rb`.
-
 Extensions to `NameError`
 -------------------------
 
diff --git a/guides/source/active_support_instrumentation.md b/guides/source/active_support_instrumentation.md
index 9d9f40e956..f495acbf68 100644
--- a/guides/source/active_support_instrumentation.md
+++ b/guides/source/active_support_instrumentation.md
@@ -19,7 +19,7 @@ After reading this guide, you will know:
 Introduction to instrumentation
 -------------------------------
 
-The instrumentation API provided by Active Support allows developers to provide hooks which other developers may hook into. There are several of these within the Rails framework, as described below in (TODO: link to section detailing each hook point). With this API, developers can choose to be notified when certain events occur inside their application or another piece of Ruby code.
+The instrumentation API provided by Active Support allows developers to provide hooks which other developers may hook into. There are several of these within the [Rails framework](#rails-framework-hooks). With this API, developers can choose to be notified when certain events occur inside their application or another piece of Ruby code.
 
 For example, there is a hook provided within Active Record that is called every time Active Record uses an SQL query on a database. This hook could be **subscribed** to, and used to track the number of queries during a certain action. There's another hook around the processing of an action of a controller. This could be used, for instance, to track how long a specific action has taken.
 
@@ -218,7 +218,7 @@ Action View
 
 ```ruby
 {
-  identifier: "/Users/adam/projects/notifications/app/views/posts/_form.html.erb",
+  identifier: "/Users/adam/projects/notifications/app/views/posts/_form.html.erb"
 }
 ```
 
@@ -232,6 +232,7 @@ Active Record
 | `:sql`           | SQL statement         |
 | `:name`          | Name of the operation |
 | `:connection_id` | `self.object_id`      |
+| `:binds`         | Bind parameters       |
 
 INFO. The adapters will add their own data as well.
 
@@ -244,13 +245,19 @@ INFO. The adapters will add their own data as well.
 }
 ```
 
-### identity.active_record
+### instantiation.active_record
 
 | Key              | Value                                     |
 | ---------------- | ----------------------------------------- |
-| `:line`          | Primary Key of object in the identity map |
-| `:name`          | Record's class                            |
-| `:connection_id` | `self.object_id`                          |
+| `:record_count`  | Number of records that instantiated       |
+| `:class_name`    | Record's class                            |
+
+```ruby
+{
+  record_count: 1,
+  class_name: "User"
+}
+```
 
 Action Mailer
 -------------
@@ -307,17 +314,6 @@ Action Mailer
 }
 ```
 
-ActiveResource
---------------
-
-### request.active_resource
-
-| Key            | Value                |
-| -------------- | -------------------- |
-| `:method`      | HTTP method          |
-| `:request_uri` | Complete URI         |
-| `:result`      | HTTP response object |
-
 Active Support
 --------------
 
@@ -400,6 +396,38 @@ INFO. Cache stores may add their own keys
 }
 ```
 
+Active Job
+--------
+
+### enqueue_at.active_job
+
+| Key          | Value                                  |
+| ------------ | -------------------------------------- |
+| `:adapter`   | QueueAdapter object processing the job |
+| `:job`       | Job object                             |
+
+### enqueue.active_job
+
+| Key          | Value                                  |
+| ------------ | -------------------------------------- |
+| `:adapter`   | QueueAdapter object processing the job |
+| `:job`       | Job object                             |
+
+### perform_start.active_job
+
+| Key          | Value                                  |
+| ------------ | -------------------------------------- |
+| `:adapter`   | QueueAdapter object processing the job |
+| `:job`       | Job object                             |
+
+### perform.active_job
+
+| Key          | Value                                  |
+| ------------ | -------------------------------------- |
+| `:adapter`   | QueueAdapter object processing the job |
+| `:job`       | Job object                             |
+
+
 Railties
 --------
 
diff --git a/guides/source/api_app.md b/guides/source/api_app.md
new file mode 100644
index 0000000000..feaaff166a
--- /dev/null
+++ b/guides/source/api_app.md
@@ -0,0 +1,404 @@
+**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.**
+
+
+Using Rails for API-only Applications
+=====================================
+
+In this guide you will learn:
+
+* What Rails provides for API-only applications
+* How to configure Rails to start without any browser features
+* How to decide which middlewares you will want to include
+* How to decide which modules to use in your controller
+
+--------------------------------------------------------------------------------
+
+What is an API app?
+-------------------
+
+Traditionally, when people said that they used Rails as an "API", they meant
+providing a programmatically accessible API alongside their web application.
+For example, GitHub provides [an API](http://developer.github.com) that you
+can use from your own custom clients.
+
+With the advent of client-side frameworks, more developers are using Rails to
+build a back-end that is shared between their web application and other native
+applications.
+
+For example, Twitter uses its [public API](https://dev.twitter.com) in its web
+application, which is built as a static site that consumes JSON resources.
+
+Instead of using Rails to generate dynamic HTML that will communicate with the
+server through forms and links, many developers are treating their web application
+as just another client, delivered as static HTML, CSS and JavaScript  consuming
+a simple JSON API.
+
+This guide covers building a Rails application that serves JSON resources to an
+API client **or** a client-side framework.
+
+Why use Rails for JSON APIs?
+----------------------------
+
+The first question a lot of people have when thinking about building a JSON API
+using Rails is: "isn't using Rails to spit out some JSON overkill? Shouldn't I
+just use something like Sinatra?".
+
+For very simple APIs, this may be true. However, even in very HTML-heavy
+applications, most of an application's logic is actually outside of the view
+layer.
+
+The reason most people use Rails is that it provides a set of defaults that
+allows us to get up and running quickly without having to make a lot of trivial
+decisions.
+
+Let's take a look at some of the things that Rails provides out of the box that are
+still applicable to API applications.
+
+Handled at the middleware layer:
+
+- Reloading: Rails applications support transparent reloading. This works even if
+  your application gets big and restarting the server for every request becomes
+  non-viable.
+- Development Mode: Rails applications come with smart defaults for development,
+  making development pleasant without compromising production-time performance.
+- Test Mode: Ditto development mode.
+- Logging: Rails applications log every request, with a level of verbosity
+  appropriate for the current mode. Rails logs in development include information
+  about the request environment, database queries, and basic performance
+  information.
+- Security: Rails detects and thwarts [IP spoofing
+  attacks](http://en.wikipedia.org/wiki/IP_address_spoofing) and handles
+  cryptographic signatures in a [timing
+  attack](http://en.wikipedia.org/wiki/Timing_attack) aware way. Don't know what
+  an IP spoofing attack or a timing attack is? Exactly.
+- Parameter Parsing: Want to specify your parameters as JSON instead of as a
+  URL-encoded String? No problem. Rails will decode the JSON for you and make
+  it available in `params`. Want to use nested URL-encoded parameters? That
+  works too.
+- Conditional GETs: Rails handles conditional `GET`, (`ETag` and `Last-Modified`),
+  processing request headers and returning the correct response headers and status
+  code. All you need to do is use the
+  [`stale?`](http://api.rubyonrails.org/classes/ActionController/ConditionalGet.html#method-i-stale-3F)
+  check in your controller, and Rails will handle all of the HTTP details for you.
+- Caching: If you use `dirty?` with public cache control, Rails will automatically
+  cache your responses. You can easily configure the cache store.
+- HEAD requests: Rails will transparently convert `HEAD` requests into `GET` ones,
+  and return just the headers on the way out. This makes `HEAD` work reliably in
+  all Rails APIs.
+
+While you could obviously build these up in terms of existing Rack middlewares,
+this list demonstrates that the default Rails middleware stack provides a lot
+of value, even if you're "just generating JSON".
+
+Handled at the Action Pack layer:
+
+- Resourceful Routing: If you're building a RESTful JSON API, you want to be
+  using the Rails router. Clean and conventional mapping from HTTP to controllers
+  means not having to spend time thinking about how to model your API in terms
+  of HTTP.
+- URL Generation: The flip side of routing is URL generation. A good API based
+  on HTTP includes URLs (see [the GitHub gist API](http://developer.github.com/v3/gists/)
+  for an example).
+- Header and Redirection Responses: `head :no_content` and
+  `redirect_to user_url(current_user)` come in handy. Sure, you could manually
+  add the response headers, but why?
+- Caching: Rails provides page, action and fragment caching. Fragment caching
+  is especially helpful when building up a nested JSON object.
+- Basic, Digest and Token Authentication: Rails comes with out-of-the-box support
+  for three kinds of HTTP authentication.
+- Instrumentation: Rails has an instrumentation API that will trigger registered
+  handlers for a variety of events, such as action processing, sending a file or
+  data, redirection, and database queries. The payload of each event comes with
+  relevant information (for the action processing event, the payload includes
+  the controller, action, parameters, request format, request method and the
+  request's full path).
+- Generators: This may be passé for advanced Rails users, but it can be nice to
+  generate a resource and get your model, controller, test stubs, and routes
+  created for you in a single command.
+- Plugins: Many third-party libraries come with support for Rails that reduce
+  or eliminate the cost of setting up and gluing together the library and the
+  web framework. This includes things like overriding default generators, adding
+  rake tasks, and honoring Rails choices (like the logger and cache back-end).
+
+Of course, the Rails boot process also glues together all registered components.
+For example, the Rails boot process is what uses your `config/database.yml` file
+when configuring Active Record.
+
+**The short version is**: you may not have thought about which parts of Rails
+are still applicable even if you remove the view layer, but the answer turns out
+to be "most of it".
+
+The Basic Configuration
+-----------------------
+
+If you're building a Rails application that will be an API server first and
+foremost, you can start with a more limited subset of Rails and add in features
+as needed.
+
+You can generate a new api Rails app:
+
+```bash
+$ rails new my_api --api
+```
+
+This will do three main things for you:
+
+- Configure your application to start with a more limited set of middlewares
+  than normal. Specifically, it will not include any middleware primarily useful
+  for browser applications (like cookies support) by default.
+- Make `ApplicationController` inherit from `ActionController::API` instead of
+  `ActionController::Base`. As with middlewares, this will leave out any Action
+  Controller modules that provide functionalities primarily used by browser
+  applications.
+- Configure the generators to skip generating views, helpers and assets when
+  you generate a new resource.
+
+If you want to take an existing application and make it an API one, read the
+following steps.
+
+In `config/application.rb` add the following line at the top of the `Application`
+class definition:
+
+```ruby
+config.api_only = true
+```
+
+Finally, inside `app/controllers/application_controller.rb`, instead of:
+
+```ruby
+class ApplicationController < ActionController::Base
+end
+```
+
+do:
+
+```ruby
+class ApplicationController < ActionController::API
+end
+```
+
+Choosing Middlewares
+--------------------
+
+An API application comes with the following middlewares by default:
+
+- `Rack::Sendfile`
+- `ActionDispatch::Static`
+- `Rack::Lock`
+- `ActiveSupport::Cache::Strategy::LocalCache::Middleware`
+- `ActionDispatch::RequestId`
+- `Rails::Rack::Logger`
+- `Rack::Runtime`
+- `ActionDispatch::ShowExceptions`
+- `ActionDispatch::DebugExceptions`
+- `ActionDispatch::RemoteIp`
+- `ActionDispatch::Reloader`
+- `ActionDispatch::Callbacks`
+- `Rack::Head`
+- `Rack::ConditionalGet`
+- `Rack::ETag`
+
+See the [internal middlewares](rails_on_rack.html#internal-middleware-stack)
+section of the Rack guide for further information on them.
+
+Other plugins, including Active Record, may add additional middlewares. In
+general, these middlewares are agnostic to the type of application you are
+building, and make sense in an API-only Rails application.
+
+You can get a list of all middlewares in your application via:
+
+```bash
+$ rake middleware
+```
+
+### Using the Cache Middleware
+
+By default, Rails will add a middleware that provides a cache store based on
+the configuration of your application (memcache by default). This means that
+the built-in HTTP cache will rely on it.
+
+For instance, using the `stale?` method:
+
+```ruby
+def show
+ @post = Post.find(params[:id])
+
+  if stale?(last_modified: @post.updated_at)
+    render json: @post
+  end
+end
+```
+
+The call to `stale?` will compare the `If-Modified-Since` header in the request
+with `@post.updated_at`. If the header is newer than the last modified, this
+action will return a "304 Not Modified" response. Otherwise, it will render the
+response and include a `Last-Modified` header in it.
+
+Normally, this mechanism is used on a per-client basis. The cache middleware
+allows us to share this caching mechanism across clients. We can enable
+cross-client caching in the call to `stale?`:
+
+```ruby
+def show
+ @post = Post.find(params[:id])
+
+  if stale?(last_modified: @post.updated_at, public: true)
+    render json: @post
+  end
+end
+```
+
+This means that the cache middleware will store off the `Last-Modified` value
+for a URL in the Rails cache, and add an `If-Modified-Since` header to any
+subsequent inbound requests for the same URL.
+
+Think of it as page caching using HTTP semantics.
+
+NOTE: This middleware is always outside of the `Rack::Lock` mutex, even in
+single-threaded applications.
+
+### Using Rack::Sendfile
+
+When you use the `send_file` method inside a Rails controller, it sets the
+`X-Sendfile` header. `Rack::Sendfile` is responsible for actually sending the
+file.
+
+If your front-end server supports accelerated file sending, `Rack::Sendfile`
+will offload the actual file sending work to the front-end server.
+
+You can configure the name of the header that your front-end server uses for
+this purpose using `config.action_dispatch.x_sendfile_header` in the appropriate
+environment's configuration file.
+
+You can learn more about how to use `Rack::Sendfile` with popular
+front-ends in [the Rack::Sendfile
+documentation](http://rubydoc.info/github/rack/rack/master/Rack/Sendfile).
+
+Here are some values for popular servers, once they are configured, to support
+accelerated file sending:
+
+```ruby
+# Apache and lighttpd
+config.action_dispatch.x_sendfile_header = "X-Sendfile"
+
+# Nginx
+config.action_dispatch.x_sendfile_header = "X-Accel-Redirect"
+```
+
+Make sure to configure your server to support these options following the
+instructions in the `Rack::Sendfile` documentation.
+
+NOTE: The `Rack::Sendfile` middleware is always outside of the `Rack::Lock`
+mutex, even in single-threaded applications.
+
+### Using ActionDispatch::Request
+
+`ActionDispatch::Request#params` will take parameters from the client in the JSON
+format and make them available in your controller inside `params`.
+
+To use this, your client will need to make a request with JSON-encoded parameters
+and specify the `Content-Type` as `application/json`.
+
+Here's an example in jQuery:
+
+```javascript
+jQuery.ajax({
+  type: 'POST',
+  url: '/people',
+  dataType: 'json',
+  contentType: 'application/json',
+  data: JSON.stringify({ person: { firstName: "Yehuda", lastName: "Katz" } }),
+  success: function(json) { }
+});
+```
+
+`ActionDispatch::Request` will see the `Content-Type` and your parameters
+will be:
+
+```ruby
+{ :person => { :firstName => "Yehuda", :lastName => "Katz" } }
+```
+
+### Other Middlewares
+
+Rails ships with a number of other middlewares that you might want to use in an
+API application, especially if one of your API clients is the browser:
+
+- `Rack::MethodOverride`
+- `ActionDispatch::Cookies`
+- `ActionDispatch::Flash`
+- For sessions management
+    * `ActionDispatch::Session::CacheStore`
+    * `ActionDispatch::Session::CookieStore`
+    * `ActionDispatch::Session::MemCacheStore`
+
+Any of these middlewares can be added via:
+
+```ruby
+config.middleware.use Rack::MethodOverride
+```
+
+### Removing Middlewares
+
+If you don't want to use a middleware that is included by default in the API-only
+middleware set, you can remove it with:
+
+```ruby
+config.middleware.delete ::Rack::Sendfile
+```
+
+Keep in mind that removing these middlewares will remove support for certain
+features in Action Controller.
+
+Choosing Controller Modules
+---------------------------
+
+An API application (using `ActionController::API`) comes with the following
+controller modules by default:
+
+- `ActionController::UrlFor`: Makes `url_for` and friends available.
+- `ActionController::Redirecting`: Support for `redirect_to`.
+- `ActionController::Rendering`: Basic support for rendering.
+- `ActionController::Renderers::All`: Support for `render :json` and friends.
+- `ActionController::ConditionalGet`: Support for `stale?`.
+- `ActionController::ForceSSL`: Support for `force_ssl`.
+- `ActionController::DataStreaming`: Support for `send_file` and `send_data`.
+- `AbstractController::Callbacks`: Support for `before_action` and friends.
+- `ActionController::Instrumentation`: Support for the instrumentation
+  hooks defined by Action Controller (see [the instrumentation
+  guide](active_support_instrumentation.html#action-controller)).
+- `ActionController::Rescue`: Support for `rescue_from`.
+- `ActionController::BasicImplicitRender`: Makes sure to return an empty response
+  if there's not an explicit one.
+- `ActionController::StrongParameters`: Support for parameters white-listing in
+  combination with Active Model mass assignment.
+- `ActionController::ParamsWrapper`: Wraps the parameters hash into a nested hash
+  so you don't have to specify root elements sending POST requests for instance.
+
+Other plugins may add additional modules. You can get a list of all modules
+included into `ActionController::API` in the rails console:
+
+```bash
+$ bin/rails c
+>> ActionController::API.ancestors - ActionController::Metal.ancestors
+```
+
+### Adding Other Modules
+
+All Action Controller modules know about their dependent modules, so you can feel
+free to include any modules into your controllers, and all dependencies will be
+included and set up as well.
+
+Some common modules you might want to add:
+
+- `AbstractController::Translation`: Support for the `l` and `t` localization
+  and translation methods.
+- `ActionController::HttpAuthentication::Basic` (or `Digest` or `Token`): Support
+  for basic, digest or token HTTP authentication.
+- `AbstractController::Layouts`: Support for layouts when rendering.
+- `ActionController::MimeResponds`: Support for `respond_to`.
+- `ActionController::Cookies`: Support for `cookies`, which includes
+  support for signed and encrypted cookies. This requires the cookies middleware.
+
+The best place to add a module is in your `ApplicationController` but you can
+also add modules to individual controllers.
diff --git a/guides/source/api_documentation_guidelines.md b/guides/source/api_documentation_guidelines.md
index b385bdbe83..73e62eb6d9 100644
--- a/guides/source/api_documentation_guidelines.md
+++ b/guides/source/api_documentation_guidelines.md
@@ -16,7 +16,8 @@ RDoc
 ----
 
 The [Rails API documentation](http://api.rubyonrails.org) is generated with
-[RDoc](http://docs.seattlerb.org/rdoc/).
+[RDoc](http://docs.seattlerb.org/rdoc/). To generate it, make sure you are
+in the rails root directory, run `bundle install` and execute:
 
 ```bash
   bundle exec rake rdoc
@@ -83,6 +84,12 @@ English
 
 Please use American English (*color*, *center*, *modularize*, etc). See [a list of American and British English spelling differences here](http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences).
 
+Oxford Comma
+------------
+
+Please use the [Oxford comma](http://en.wikipedia.org/wiki/Serial_comma)
+("red, white, and blue", instead of "red, white and blue").
+
 Example Code
 ------------
 
@@ -233,7 +240,7 @@ You can quickly test the RDoc output with the following command:
 
 ```
 $ echo "+:to_param+" | rdoc --pipe
-#=> <p><code>:to_param</code></p>
+# => <p><code>:to_param</code></p>
 ```
 
 ### Regular Font
diff --git a/guides/source/asset_pipeline.md b/guides/source/asset_pipeline.md
index 52ea605a72..41881abb62 100644
--- a/guides/source/asset_pipeline.md
+++ b/guides/source/asset_pipeline.md
@@ -149,7 +149,7 @@ clients to fetch them again, even when the content of those assets has not chang
 Fingerprinting fixes these problems by avoiding query strings, and by ensuring
 that filenames are consistent based on their content.
 
-Fingerprinting is enabled by default for both the development and production 
+Fingerprinting is enabled by default for both the development and production
 environments. You can enable or disable it in your configuration through the
 `config.assets.digest` option.
 
@@ -209,7 +209,7 @@ precompiling works.
 
 NOTE: You must have an ExecJS supported runtime in order to use CoffeeScript.
 If you are using Mac OS X or Windows, you have a JavaScript runtime installed in
-your operating system. Check [ExecJS](https://github.com/sstephenson/execjs#readme) documentation to know all supported JavaScript runtimes.
+your operating system. Check [ExecJS](https://github.com/rails/execjs#readme) documentation to know all supported JavaScript runtimes.
 
 You can also disable generation of controller specific asset files by adding the
 following to your `config/application.rb` configuration:
@@ -403,13 +403,13 @@ When using the asset pipeline, paths to assets must be re-written and
 underscored in Ruby) for the following asset classes: image, font, video, audio,
 JavaScript and stylesheet.
 
-* `image-url("rails.png")` becomes `url(/assets/rails.png)`
-* `image-path("rails.png")` becomes `"/assets/rails.png"`.
+* `image-url("rails.png")` returns `url(/assets/rails.png)`
+* `image-path("rails.png")` returns `"/assets/rails.png"`
 
 The more generic form can also be used:
 
-* `asset-url("rails.png")` becomes `url(/assets/rails.png)`
-* `asset-path("rails.png")` becomes `"/assets/rails.png"`
+* `asset-url("rails.png")` returns `url(/assets/rails.png)`
+* `asset-path("rails.png")` returns `"/assets/rails.png"`
 
 #### JavaScript/CoffeeScript and ERB
 
@@ -643,7 +643,7 @@ above. By default Rails assumes assets have been precompiled and will be
 served as static assets by your web server.
 
 During the precompilation phase an MD5 is generated from the contents of the
-compiled files, and inserted into the filenames as they are written to disc.
+compiled files, and inserted into the filenames as they are written to disk.
 These fingerprinted names are used by the Rails helpers in place of the manifest
 name.
 
@@ -662,13 +662,12 @@ generates something like this:
 rel="stylesheet" />
 ```
 
-Note: with the Asset Pipeline the :cache and :concat options aren't used
+NOTE: with the Asset Pipeline the `:cache` and `:concat` options aren't used
 anymore, delete these options from the `javascript_include_tag` and
 `stylesheet_link_tag`.
 
 The fingerprinting behavior is controlled by the `config.assets.digest`
-initialization option (which defaults to `true` for production and `false` for
-everything else).
+initialization option (which defaults to `true` for production and development).
 
 NOTE: Under normal circumstances the default `config.assets.digest` option
 should not be changed. If there are no digests in the filenames, and far-future
@@ -729,27 +728,6 @@ include, you can add them to the `precompile` array in `config/initializers/asse
 Rails.application.config.assets.precompile += ['admin.js', 'admin.css', 'swfObject.js']
 ```
 
-Or, you can opt to precompile all assets with something like this:
-
-```ruby
-# config/initializers/assets.rb
-Rails.application.config.assets.precompile << Proc.new do |path|
-  if path =~ /\.(css|js)\z/
-    full_path = Rails.application.assets.resolve(path).to_path
-    app_assets_path = Rails.root.join('app', 'assets').to_path
-    if full_path.starts_with? app_assets_path
-      logger.info "including asset: " + full_path
-      true
-    else
-      logger.info "excluding asset: " + full_path
-      false
-    end
-  else
-    false
-  end
-end
-```
-
 NOTE. Always specify an expected compiled filename that ends with .js or .css,
 even if you want to add Sass or CoffeeScript files to the precompile array.
 
@@ -812,41 +790,6 @@ location ~ ^/assets/ {
 }
 ```
 
-#### GZip Compression
-
-When files are precompiled, Sprockets also creates a
-[gzipped](http://en.wikipedia.org/wiki/Gzip) (.gz) version of your assets. Web
-servers are typically configured to use a moderate compression ratio as a
-compromise, but since precompilation happens once, Sprockets uses the maximum
-compression ratio, thus reducing the size of the data transfer to the minimum.
-On the other hand, web servers can be configured to serve compressed content
-directly from disk, rather than deflating non-compressed files themselves.
-
-NGINX is able to do this automatically enabling `gzip_static`:
-
-```nginx
-location ~ ^/(assets)/  {
-  root /path/to/public;
-  gzip_static on; # to serve pre-gzipped version
-  expires max;
-  add_header Cache-Control public;
-}
-```
-
-This directive is available if the core module that provides this feature was
-compiled with the web server. Ubuntu/Debian packages, even `nginx-light`, have
-the module compiled. Otherwise, you may need to perform a manual compilation:
-
-```bash
-./configure --with-http_gzip_static_module
-```
-
-If you're compiling NGINX with Phusion Passenger you'll need to pass that option
-when prompted.
-
-A robust configuration for Apache is possible but tricky; please Google around.
-(Or help update this Guide if you have a good configuration example for Apache.)
-
 ### Local Precompilation
 
 There are several reasons why you might want to precompile your assets locally.
@@ -942,7 +885,7 @@ focus on serving application code as fast as possible.
 #### Set up a CDN to Serve Static Assets
 
 To set up your CDN you have to have your application running in production on
-the internet at a publically available URL, for example `example.com`. Next
+the internet at a publicly available URL, for example `example.com`. Next
 you'll need to sign up for a CDN service from a cloud hosting provider. When you
 do this you need to configure the "origin" of the CDN to point back at your
 website `example.com`, check your provider for documentation on configuring the
@@ -995,7 +938,7 @@ http://mycdnsubdomain.fictional-cdn.com/assets/smile.png
 
 If the CDN has a copy of `smile.png` it will serve it to the browser and your
 server doesn't even know it was requested. If the CDN does not have a copy it
-will try to find it a the "origin" `example.com/assets/smile.png` and then store
+will try to find it at the "origin" `example.com/assets/smile.png` and then store
 it for future use.
 
 If you want to serve only some assets from your CDN, you can use custom `:host`
@@ -1158,7 +1101,7 @@ The following line invokes `uglifier` for JavaScript compression.
 config.assets.js_compressor = :uglifier
 ```
 
-NOTE: You will need an [ExecJS](https://github.com/sstephenson/execjs#readme)
+NOTE: You will need an [ExecJS](https://github.com/rails/execjs#readme)
 supported runtime in order to use `uglifier`. If you are using Mac OS X or
 Windows you have a JavaScript runtime installed in your operating system.
 
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index dab885a8fb..999c533fb3 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -146,6 +146,17 @@ class CreateSuppliers < ActiveRecord::Migration
 end
 ```
 
+Depending on the use case, you might also need to create a unique index and/or
+a foreign key constraint on the supplier column for the accounts table. In this
+case, the column definition might look like this:
+
+```ruby
+create_table :accounts do |t|
+  t.belongs_to :supplier, index: true, unique: true, foreign_key: true
+  # ...
+end
+```
+
 ### The `has_many` Association
 
 A `has_many` association indicates a one-to-many connection with another model. You'll often find this association on the "other side" of a `belongs_to` association. This association indicates that each instance of the model has zero or more instances of another model. For example, in an application containing customers and orders, the customer model could be declared like this:
@@ -171,7 +182,7 @@ class CreateCustomers < ActiveRecord::Migration
     end
 
     create_table :orders do |t|
-      t.belongs_to :customer, index:true
+      t.belongs_to :customer, index: true
       t.datetime :order_date
       t.timestamps null: false
     end
@@ -424,7 +435,7 @@ end
 
 The simplest rule of thumb is that you should set up a `has_many :through` relationship if you need to work with the relationship model as an independent entity. If you don't need to do anything with the relationship model, it may be simpler to set up a `has_and_belongs_to_many` relationship (though you'll need to remember to create the joining table in the database).
 
-You should use `has_many :through` if you need validations, callbacks, or extra attributes on the join model.
+You should use `has_many :through` if you need validations, callbacks or extra attributes on the join model.
 
 ### Polymorphic Associations
 
@@ -460,7 +471,7 @@ class CreatePictures < ActiveRecord::Migration
       t.timestamps null: false
     end
 
-    add_index :pictures, :imageable_id
+    add_index :pictures, [:imageable_type, :imageable_id]
   end
 end
 ```
@@ -579,7 +590,7 @@ If you create an association some time after you build the underlying model, you
 
 If you create a `has_and_belongs_to_many` association, you need to explicitly create the joining table. Unless the name of the join table is explicitly specified by using the `:join_table` option, Active Record creates the name by using the lexical order of the class names. So a join between customer and order models will give the default join table name of "customers_orders" because "c" outranks "o" in lexical ordering.
 
-WARNING: The precedence between model names is calculated using the `<` operator for `String`. This means that if the strings are of different lengths, and the strings are equal when compared up to the shortest length, then the longer string is considered of higher lexical precedence than the shorter one. For example, one would expect the tables "paper_boxes" and "papers" to generate a join table name of "papers_paper_boxes" because of the length of the name "paper_boxes", but it in fact generates a join table name of "paper_boxes_papers" (because the underscore '_' is lexicographically _less_ than 's' in common encodings).
+WARNING: The precedence between model names is calculated using the `<=>` operator for `String`. This means that if the strings are of different lengths, and the strings are equal when compared up to the shortest length, then the longer string is considered of higher lexical precedence than the shorter one. For example, one would expect the tables "paper_boxes" and "papers" to generate a join table name of "papers_paper_boxes" because of the length of the name "paper_boxes", but it in fact generates a join table name of "paper_boxes_papers" (because the underscore '\_' is lexicographically _less_ than 's' in common encodings).
 
 Whatever the name, you must manually generate the join table with an appropriate migration. For example, consider these associations:
 
@@ -609,7 +620,20 @@ class CreateAssembliesPartsJoinTable < ActiveRecord::Migration
 end
 ```
 
-We pass `id: false` to `create_table` because that table does not represent a model. That's required for the association to work properly. If you observe any strange behavior in a `has_and_belongs_to_many` association like mangled models IDs, or exceptions about conflicting IDs, chances are you forgot that bit.
+We pass `id: false` to `create_table` because that table does not represent a model. That's required for the association to work properly. If you observe any strange behavior in a `has_and_belongs_to_many` association like mangled model IDs, or exceptions about conflicting IDs, chances are you forgot that bit.
+
+You can also use the method `create_join_table`
+
+```ruby
+class CreateAssembliesPartsJoinTable < ActiveRecord::Migration
+  def change
+    create_join_table :assemblies, :parts do |t|
+      t.index :assembly_id
+      t.index :part_id
+    end
+  end
+end
+```
 
 ### Controlling Association Scope
 
@@ -691,7 +715,7 @@ c.first_name = 'Manny'
 c.first_name == o.customer.first_name # => false
 ```
 
-This happens because c and o.customer are two different in-memory representations of the same data, and neither one is automatically refreshed from changes to the other. Active Record provides the `:inverse_of` option so that you can inform it of these relations:
+This happens because `c` and `o.customer` are two different in-memory representations of the same data, and neither one is automatically refreshed from changes to the other. Active Record provides the `:inverse_of` option so that you can inform it of these relations:
 
 ```ruby
 class Customer < ActiveRecord::Base
@@ -726,10 +750,10 @@ Most associations with standard names will be supported. However, associations
 that contain the following options will not have their inverses set
 automatically:
 
-* :conditions
-* :through
-* :polymorphic
-* :foreign_key
+* `:conditions`
+* `:through`
+* `:polymorphic`
+* `:foreign_key`
 
 Detailed Association Reference
 ------------------------------
@@ -744,7 +768,7 @@ The `belongs_to` association creates a one-to-one match with another model. In d
 
 When you declare a `belongs_to` association, the declaring class automatically gains five methods related to the association:
 
-* `association(force_reload = false)`
+* `association`
 * `association=(associate)`
 * `build_association(attributes = {})`
 * `create_association(attributes = {})`
@@ -770,7 +794,7 @@ create_customer!
 
 NOTE: When initializing a new `has_one` or `belongs_to` association you must use the `build_` prefix to build the association, rather than the `association.build` method that would be used for `has_many` or `has_and_belongs_to_many` associations. To create one, use the `create_` prefix.
 
-##### `association(force_reload = false)`
+##### `association`
 
 The `association` method returns the associated object, if any. If no associated object is found, it returns `nil`.
 
@@ -778,11 +802,15 @@ The `association` method returns the associated object, if any. If no associated
 @customer = @order.customer
 ```
 
-If the associated object has already been retrieved from the database for this object, the cached version will be returned. To override this behavior (and force a database read), pass `true` as the `force_reload` argument.
+If the associated object has already been retrieved from the database for this object, the cached version will be returned. To override this behavior (and force a database read), call `#reload` on the parent object.
+
+```ruby
+@customer = @order.reload.customer
+```
 
 ##### `association=(associate)`
 
-The `association=` method assigns an associated object to this object. Behind the scenes, this means extracting the primary key from the associate object and setting this object's foreign key to the same value.
+The `association=` method assigns an associated object to this object. Behind the scenes, this means extracting the primary key from the associated object and setting this object's foreign key to the same value.
 
 ```ruby
 @order.customer = @customer
@@ -829,10 +857,12 @@ The `belongs_to` association supports these options:
 * `:counter_cache`
 * `:dependent`
 * `:foreign_key`
+* `:primary_key`
 * `:inverse_of`
 * `:polymorphic`
 * `:touch`
 * `:validate`
+* `:optional`
 
 ##### `:autosave`
 
@@ -874,18 +904,26 @@ end
 
 With this declaration, Rails will keep the cache value up to date, and then return that value in response to the `size` method.
 
-Although the `:counter_cache` option is specified on the model that includes the `belongs_to` declaration, the actual column must be added to the _associated_ model. In the case above, you would need to add a column named `orders_count` to the `Customer` model. You can override the default column name if you need to:
+Although the `:counter_cache` option is specified on the model that includes
+the `belongs_to` declaration, the actual column must be added to the
+_associated_ (`has_many`) model. In the case above, you would need to add a
+column named `orders_count` to the `Customer` model.
+
+You can override the default column name by specifying a custom column name in
+the `counter_cache` declaration instead of `true`. For example, to use
+`count_of_orders` instead of `orders_count`:
 
 ```ruby
 class Order < ActiveRecord::Base
   belongs_to :customer, counter_cache: :count_of_orders
 end
 class Customer < ActiveRecord::Base
-  has_many :orders, counter_cache: :count_of_orders
+  has_many :orders
 end
 ```
 
-NOTE: You only need to specify the :counter_cache option on the "has_many side" of the association when using a custom name for the counter cache.
+NOTE: You only need to specify the :counter_cache option on the `belongs_to`
+side of the association.
 
 Counter cache columns are added to the containing model's list of read-only attributes through `attr_readonly`.
 
@@ -894,8 +932,11 @@ If you set the `:dependent` option to:
 
 * `:destroy`, when the object is destroyed, `destroy` will be called on its
 associated objects.
-* `:delete`, when the object is destroyed, all its associated objects will be
+* `:delete_all`, when the object is destroyed, all its associated objects will be
 deleted directly from the database without calling their `destroy` method.
+* `:nullify`, causes the foreign key to be set to `NULL`. Callbacks are not executed.
+* `:restrict_with_exception`, causes an exception to be raised if there is an associated record
+* `:restrict_with_error`, causes an error to be added to the owner if there is an associated object
 
 WARNING: You should not specify this option on a `belongs_to` association that is connected with a `has_many` association on the other class. Doing so can lead to orphaned records in your database.
 
@@ -912,6 +953,26 @@ end
 
 TIP: In any case, Rails will not create foreign key columns for you. You need to explicitly define them as part of your migrations.
 
+##### `:primary_key`
+
+By convention, Rails assumes that the `id` column is used to hold the primary key
+of its tables. The `:primary_key` option allows you to specify a different column.
+
+For example, given we have a `users` table with `guid` as the primary key. If we want a separate `todos` table to hold the foreign key `user_id` in the `guid` column, then we can use `primary_key` to achieve this like so:
+
+```ruby
+class User < ActiveRecord::Base
+  self.primary_key = 'guid' # primary key is guid and not id
+end
+
+class Todo < ActiveRecord::Base
+  belongs_to :user, primary_key: 'guid'
+end
+```
+
+When we execute `@user.todos.create` then the `@todo` record will have its
+`user_id` value as the `guid` value of `@user`.
+
 ##### `:inverse_of`
 
 The `:inverse_of` option specifies the name of the `has_many` or `has_one` association that is the inverse of this association. Does not work in combination with the `:polymorphic` options.
@@ -932,7 +993,7 @@ Passing `true` to the `:polymorphic` option indicates that this is a polymorphic
 
 ##### `:touch`
 
-If you set the `:touch` option to `:true`, then the `updated_at` or `updated_on` timestamp on the associated object will be set to the current time whenever this object is saved or destroyed:
+If you set the `:touch` option to `true`, then the `updated_at` or `updated_on` timestamp on the associated object will be set to the current time whenever this object is saved or destroyed:
 
 ```ruby
 class Order < ActiveRecord::Base
@@ -956,6 +1017,11 @@ end
 
 If you set the `:validate` option to `true`, then associated objects will be validated whenever you save this object. By default, this is `false`: associated objects will not be validated when this object is saved.
 
+##### `:optional`
+
+If you set the `:optional` option to `true`, then the presence of the associated
+object won't be validated. By default, this option is set to `false`.
+
 #### Scopes for `belongs_to`
 
 There may be times when you wish to customize the query used by `belongs_to`. Such customizations can be achieved via a scope block. For example:
@@ -1054,7 +1120,7 @@ The `has_one` association creates a one-to-one match with another model. In data
 
 When you declare a `has_one` association, the declaring class automatically gains five methods related to the association:
 
-* `association(force_reload = false)`
+* `association`
 * `association=(associate)`
 * `build_association(attributes = {})`
 * `create_association(attributes = {})`
@@ -1080,7 +1146,7 @@ create_account!
 
 NOTE: When initializing a new `has_one` or `belongs_to` association you must use the `build_` prefix to build the association, rather than the `association.build` method that would be used for `has_many` or `has_and_belongs_to_many` associations. To create one, use the `create_` prefix.
 
-##### `association(force_reload = false)`
+##### `association`
 
 The `association` method returns the associated object, if any. If no associated object is found, it returns `nil`.
 
@@ -1088,11 +1154,15 @@ The `association` method returns the associated object, if any. If no associated
 @account = @supplier.account
 ```
 
-If the associated object has already been retrieved from the database for this object, the cached version will be returned. To override this behavior (and force a database read), pass `true` as the `force_reload` argument.
+If the associated object has already been retrieved from the database for this object, the cached version will be returned. To override this behavior (and force a database read), call `#reload` on the parent object.
+
+```ruby
+@account = @supplier.reload.account
+```
 
 ##### `association=(associate)`
 
-The `association=` method assigns an associated object to this object. Behind the scenes, this means extracting the primary key from this object and setting the associate object's foreign key to the same value.
+The `association=` method assigns an associated object to this object. Behind the scenes, this means extracting the primary key from this object and setting the associated object's foreign key to the same value.
 
 ```ruby
 @supplier.account = @account
@@ -1173,8 +1243,8 @@ Controls what happens to the associated object when its owner is destroyed:
 It's necessary not to set or leave `:nullify` option for those associations
 that have `NOT NULL` database constraints. If you don't set `dependent` to
 destroy such associations you won't be able to change the associated object
-because initial associated object foreign key will be set to unallowed `NULL`
-value.
+because the initial associated object's foreign key will be set to the
+unallowed `NULL` value.
 
 ##### `:foreign_key`
 
@@ -1321,7 +1391,7 @@ The `has_many` association creates a one-to-many relationship with another model
 
 When you declare a `has_many` association, the declaring class automatically gains 16 methods related to the association:
 
-* `collection(force_reload = false)`
+* `collection`
 * `collection<<(object, ...)`
 * `collection.delete(object, ...)`
 * `collection.destroy(object, ...)`
@@ -1349,7 +1419,7 @@ end
 Each instance of the `Customer` model will have these methods:
 
 ```ruby
-orders(force_reload = false)
+orders
 orders<<(object, ...)
 orders.delete(object, ...)
 orders.destroy(object, ...)
@@ -1367,7 +1437,7 @@ orders.create(attributes = {})
 orders.create!(attributes = {})
 ```
 
-##### `collection(force_reload = false)`
+##### `collection`
 
 The `collection` method returns an array of all of the associated objects. If there are no associated objects, it returns an empty array.
 
@@ -1421,7 +1491,14 @@ The `collection_singular_ids=` method makes the collection contain only the obje
 
 ##### `collection.clear`
 
-The `collection.clear` method removes every object from the collection. This destroys the associated objects if they are associated with `dependent: :destroy`, deletes them directly from the database if `dependent: :delete_all`, and otherwise sets their foreign keys to `NULL`.
+The `collection.clear` method removes all objects from the collection according to the strategy specified by the `dependent` option. If no option is given, it follows the default strategy. The default strategy for `has_many :through` associations is `delete_all`, and for `has_many` associations is to set the foreign keys to `NULL`.
+
+```ruby
+@customer.orders.clear
+```
+
+WARNING: Objects will be deleted if they're associated with `dependent: :destroy`,
+just like `dependent: :delete_all`.
 
 ##### `collection.empty?`
 
@@ -1460,24 +1537,36 @@ The `collection.where` method finds objects within the collection based on the c
 
 ##### `collection.exists?(...)`
 
-The `collection.exists?` method checks whether an object meeting the supplied conditions exists in the collection. It uses the same syntax and options as `ActiveRecord::Base.exists?`.
+The `collection.exists?` method checks whether an object meeting the supplied
+conditions exists in the collection. It uses the same syntax and options as
+[`ActiveRecord::Base.exists?`](http://api.rubyonrails.org/classes/ActiveRecord/FinderMethods.html#method-i-exists-3F).
 
 ##### `collection.build(attributes = {}, ...)`
 
-The `collection.build` method returns one or more new objects of the associated type. These objects will be instantiated from the passed attributes, and the link through their foreign key will be created, but the associated objects will _not_ yet be saved.
+The `collection.build` method returns a single or array of new objects of the associated type. The object(s) will be instantiated from the passed attributes, and the link through their foreign key will be created, but the associated objects will _not_ yet be saved.
 
 ```ruby
 @order = @customer.orders.build(order_date: Time.now,
                                 order_number: "A12345")
+
+@orders = @customer.orders.build([
+  { order_date: Time.now, order_number: "A12346" },
+  { order_date: Time.now, order_number: "A12347" }
+])
 ```
 
 ##### `collection.create(attributes = {})`
 
-The `collection.create` method returns a new object of the associated type. This object will be instantiated from the passed attributes, the link through its foreign key will be created, and, once it passes all of the validations specified on the associated model, the associated object _will_ be saved.
+The `collection.create` method returns a single or array of new objects of the associated type. The object(s) will be instantiated from the passed attributes, the link through its foreign key will be created, and, once it passes all of the validations specified on the associated model, the associated object _will_ be saved.
 
 ```ruby
 @order = @customer.orders.create(order_date: Time.now,
                                  order_number: "A12345")
+
+@orders = @customer.orders.create([
+  { order_date: Time.now, order_number: "A12346" },
+  { order_date: Time.now, order_number: "A12347" }
+])
 ```
 
 ##### `collection.create!(attributes = {})`
@@ -1490,7 +1579,7 @@ While Rails uses intelligent defaults that will work well in most situations, th
 
 ```ruby
 class Customer < ActiveRecord::Base
-  has_many :orders, dependent: :delete_all, validate: :false
+  has_many :orders, dependent: :delete_all, validate: false
 end
 ```
 
@@ -1571,9 +1660,10 @@ end
 
 By convention, Rails assumes that the column used to hold the primary key of the association is `id`. You can override this and explicitly specify the primary key with the `:primary_key` option.
 
-Let's say that `users` table has `id` as the primary_key but it also has
-`guid` column. And the requirement is that `todos` table should hold
-`guid` column value and not `id` value. This can be achieved like this
+Let's say the `users` table has `id` as the primary_key but it also
+has a `guid` column. The requirement is that the `todos` table should
+hold the `guid` column value as the foreign key and not `id`
+value. This can be achieved like this:
 
 ```ruby
 class User < ActiveRecord::Base
@@ -1581,8 +1671,8 @@ class User < ActiveRecord::Base
 end
 ```
 
-Now if we execute `@user.todos.create` then `@todo` record will have
-`user_id` value as the `guid` value of `@user`.
+Now if we execute `@todo = @user.todos.create` then the `@todo`
+record's `user_id` value will be the `guid` value of `@user`.
 
 
 ##### `:source`
@@ -1622,7 +1712,7 @@ You can use any of the standard [querying methods](active_record_querying.html)
 * `order`
 * `readonly`
 * `select`
-* `uniq`
+* `distinct`
 
 ##### `where`
 
@@ -1813,7 +1903,7 @@ The `has_and_belongs_to_many` association creates a many-to-many relationship wi
 
 When you declare a `has_and_belongs_to_many` association, the declaring class automatically gains 16 methods related to the association:
 
-* `collection(force_reload = false)`
+* `collection`
 * `collection<<(object, ...)`
 * `collection.delete(object, ...)`
 * `collection.destroy(object, ...)`
@@ -1841,7 +1931,7 @@ end
 Each instance of the `Part` model will have these methods:
 
 ```ruby
-assemblies(force_reload = false)
+assemblies
 assemblies<<(object, ...)
 assemblies.delete(object, ...)
 assemblies.destroy(object, ...)
@@ -1866,7 +1956,7 @@ If the join table for a `has_and_belongs_to_many` association has additional col
 WARNING: The use of extra attributes on the join table in a `has_and_belongs_to_many` association is deprecated. If you require this sort of complex behavior on the table that joins two models in a many-to-many relationship, you should use a `has_many :through` association instead of `has_and_belongs_to_many`.
 
 
-##### `collection(force_reload = false)`
+##### `collection`
 
 The `collection` method returns an array of all of the associated objects. If there are no associated objects, it returns an empty array.
 
@@ -1958,7 +2048,9 @@ The `collection.where` method finds objects within the collection based on the c
 
 ##### `collection.exists?(...)`
 
-The `collection.exists?` method checks whether an object meeting the supplied conditions exists in the collection. It uses the same syntax and options as `ActiveRecord::Base.exists?`.
+The `collection.exists?` method checks whether an object meeting the supplied
+conditions exists in the collection. It uses the same syntax and options as
+[`ActiveRecord::Base.exists?`](http://api.rubyonrails.org/classes/ActiveRecord/FinderMethods.html#method-i-exists-3F).
 
 ##### `collection.build(attributes = {})`
 
@@ -1986,8 +2078,8 @@ While Rails uses intelligent defaults that will work well in most situations, th
 
 ```ruby
 class Parts < ActiveRecord::Base
-  has_and_belongs_to_many :assemblies, autosave: true,
-                                       readonly: true
+  has_and_belongs_to_many :assemblies, -> { readonly },
+                                       autosave: true
 end
 ```
 
@@ -1999,7 +2091,6 @@ The `has_and_belongs_to_many` association supports these options:
 * `:foreign_key`
 * `:join_table`
 * `:validate`
-* `:readonly`
 
 ##### `:association_foreign_key`
 
@@ -2243,3 +2334,67 @@ Extensions can refer to the internals of the association proxy using these three
 * `proxy_association.owner` returns the object that the association is a part of.
 * `proxy_association.reflection` returns the reflection object that describes the association.
 * `proxy_association.target` returns the associated object for `belongs_to` or `has_one`, or the collection of associated objects for `has_many` or `has_and_belongs_to_many`.
+
+Single Table Inheritance
+------------------------
+
+Sometimes, you may want to share fields and behavior between different models.
+Let's say we have Car, Motorcycle and Bicycle models. We will want to share
+the `color` and `price` fields and some methods for all of them, but having some
+specific behavior for each, and separated controllers too.
+
+Rails makes this quite easy. First, let's generate the base Vehicle model:
+
+```bash
+$ rails generate model vehicle type:string color:string price:decimal{10.2}
+```
+
+Did you note we are adding a "type" field? Since all models will be saved in a
+single database table, Rails will save in this column the name of the model that
+is being saved. In our example, this can be "Car", "Motorcycle" or "Bicycle."
+STI won't work without a "type" field in the table.
+
+Next, we will generate the three models that inherit from Vehicle. For this,
+we can use the `--parent=PARENT` option, which will generate a model that
+inherits from the specified parent and without equivalent migration (since the
+table already exists).
+
+For example, to generate the Car model:
+
+```bash
+$ rails generate model car --parent=Vehicle
+```
+
+The generated model will look like this:
+
+```ruby
+class Car < Vehicle
+end
+```
+
+This means that all behavior added to Vehicle is available for Car too, as
+associations, public methods, etc.
+
+Creating a car will save it in the `vehicles` table with "Car" as the `type` field:
+
+```ruby
+Car.create(color: 'Red', price: 10000)
+```
+
+will generate the following SQL:
+
+```sql
+INSERT INTO "vehicles" ("type", "color", "price") VALUES ('Car', 'Red', 10000)
+```
+
+Querying car records will just search for vehicles that are cars:
+
+```ruby
+Car.all
+```
+
+will run a query like:
+
+```sql
+SELECT "vehicles".* FROM "vehicles" WHERE "vehicles"."type" IN ('Car')
+```
diff --git a/guides/source/autoloading_and_reloading_constants.md b/guides/source/autoloading_and_reloading_constants.md
index f32714f893..2b6d7e4044 100644
--- a/guides/source/autoloading_and_reloading_constants.md
+++ b/guides/source/autoloading_and_reloading_constants.md
@@ -80,7 +80,8 @@ end
 ```
 
 The *nesting* at any given place is the collection of enclosing nested class and
-module objects outwards. For example, in the previous example, the nesting at
+module objects outwards. The nesting at any given place can be inspected with
+`Module.nesting`. For example, in the previous example, the nesting at
 (1) is
 
 ```ruby
@@ -113,6 +114,16 @@ certain nesting does not necessarily correlate with the namespaces at the spot.
 Even more, they are totally independent, take for instance
 
 ```ruby
+module X
+  module Y
+  end
+end
+
+module A
+  module B
+  end
+end
+
 module X::Y
   module A::B
     # (3)
@@ -140,9 +151,10 @@ executed, and popped after it.
 
 * A singleton class opened with `class << object` gets pushed, and popped later.
 
-* When any of the `*_eval` family of methods is called using a string argument,
+* When `instance_eval` is called using a string argument,
 the singleton class of the receiver is pushed to the nesting of the eval'ed
-code.
+code. When `class_eval` or `module_eval` is called using a string argument,
+the receiver is pushed to the nesting of the eval'ed code.
 
 * The nesting at the top-level of code interpreted by `Kernel#load` is empty
 unless the `load` call receives a true value as second argument, in which case
@@ -153,8 +165,6 @@ the blocks that may be passed to `Class.new` and `Module.new` do not get the
 class or module being defined pushed to their nesting. That's one of the
 differences between defining classes and modules in one way or another.
 
-The nesting at any given place can be inspected with `Module.nesting`.
-
 ### Class and Module Definitions are Constant Assignments
 
 Let's suppose the following snippet creates a class (rather than reopening it):
@@ -236,7 +246,7 @@ end
 ```
 
 `Post` is not syntax for a class. Rather, `Post` is a regular Ruby constant. If
-all is good, the constant evaluates to an object that responds to `all`.
+all is good, the constant is evaluated to an object that responds to `all`.
 
 That is why we talk about *constant* autoloading, Rails has the ability to
 load constants on the fly.
@@ -291,7 +301,9 @@ order. The ancestors of those elements are ignored.
 
 2. If not found, then the algorithm walks up the ancestor chain of the cref.
 
-3. If not found, `const_missing` is invoked on the cref. The default
+3. If not found and the cref is a module, the constant is looked up in `Object`.
+
+4. If not found, `const_missing` is invoked on the cref. The default
 implementation of `const_missing` raises `NameError`, but it can be overridden.
 
 Rails autoloading **does not emulate this algorithm**, but its starting point is
@@ -314,7 +326,7 @@ relative: `::Billing::Invoice`. That would force `Billing` to be looked up
 only as a top-level constant.
 
 `Invoice` on the other hand is qualified by `Billing` and we are going to see
-its resolution next. Let's call *parent* to that qualifying class or module
+its resolution next. Let's define *parent* to be that qualifying class or module
 object, that is, `Billing` in the example above. The algorithm for qualified
 constants goes like this:
 
@@ -451,9 +463,11 @@ Also, this collection is configurable via `config.autoload_paths`. For example,
 by adding this to `config/application.rb`:
 
 ```ruby
-config.autoload_paths += "#{Rails.root}/lib"
+config.autoload_paths << "#{Rails.root}/lib"
 ```
 
+`config.autoload_paths` is not changeable from environment-specific configuration files.
+
 The value of `autoload_paths` can be inspected. In a just generated application
 it is (edited):
 
@@ -685,12 +699,12 @@ creates an empty module and assigns it to the `Admin` constant on the fly.
 ### Generic Procedure
 
 Relative references are reported to be missing in the cref where they were hit,
-and qualified references are reported to be missing in their parent. (See
+and qualified references are reported to be missing in their parent (see
 [Resolution Algorithm for Relative
 Constants](#resolution-algorithm-for-relative-constants) at the beginning of
 this guide for the definition of *cref*, and [Resolution Algorithm for Qualified
 Constants](#resolution-algorithm-for-qualified-constants) for the definition of
-*parent*.)
+*parent*).
 
 The procedure to autoload constant `C` in an arbitrary situation is as follows:
 
@@ -868,8 +882,8 @@ end
 ```
 
 To resolve `User` Ruby checks `Admin` in the former case, but it does not in
-the latter because it does not belong to the nesting. (See [Nesting](#nesting)
-and [Resolution Algorithms](#resolution-algorithms).)
+the latter because it does not belong to the nesting (see [Nesting](#nesting)
+and [Resolution Algorithms](#resolution-algorithms)).
 
 Unfortunately Rails autoloading does not know the nesting in the spot where the
 constant was missing and so it is not able to act as Ruby would. In particular,
@@ -1284,7 +1298,7 @@ c.user # NameError: uninitialized constant C::User
 ```
 
 because it detects that a parent namespace already has the constant (see [Qualified
-References](#autoloading-algorithms-qualified-references).)
+References](#autoloading-algorithms-qualified-references)).
 
 As with pure Ruby, within the body of a direct descendant of `BasicObject` use
 always absolute constant paths:
diff --git a/guides/source/caching_with_rails.md b/guides/source/caching_with_rails.md
index 0fa20f7ccf..9a56233e4a 100644
--- a/guides/source/caching_with_rails.md
+++ b/guides/source/caching_with_rails.md
@@ -1,14 +1,26 @@
 **DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.**
 
-Caching with Rails: An overview
+Caching with Rails: An Overview
 ===============================
 
-This guide will teach you what you need to know about avoiding that expensive round-trip to your database and returning what you need to return to the web clients in the shortest time possible.
+This guide is an introduction to speeding up your Rails application with caching.
+
+Caching means to store content generated during the request-response cycle and
+to reuse it when responding to similar requests.
+
+Caching is often the most effective way to boost an application's performance.
+Through caching, web sites running on a single server with a single database
+can sustain a load of thousands of concurrent users.
+
+Rails provides a set of caching features out of the box. This guide will teach
+you the scope and purpose of each one of them. Master these techniques and your
+Rails applications can serve millions of views without exorbitant response times
+or server bills.
 
 After reading this guide, you will know:
 
-* Page and action caching (moved to separate gems as of Rails 4).
-* Fragment caching.
+* Fragment and Russian doll caching.
+* How to manage the caching dependencies.
 * Alternative cache stores.
 * Conditional GET support.
 
@@ -18,21 +30,34 @@ Basic Caching
 -------------
 
 This is an introduction to three types of caching techniques: page, action and
-fragment caching. Rails provides by default fragment caching. In order to use
-page and action caching, you will need to add `actionpack-page_caching` and
+fragment caching. By default Rails provides fragment caching. In order to use
+page and action caching you will need to add `actionpack-page_caching` and
 `actionpack-action_caching` to your Gemfile.
 
-To start playing with caching you'll want to ensure that `config.action_controller.perform_caching` is set to `true`, if you're running in development mode. This flag is normally set in the corresponding `config/environments/*.rb` and caching is disabled by default for development and test, and enabled for production.
+By default, caching is only enabled in your production environment. To play
+around with caching locally you'll want to enable caching in your local
+environment by setting `config.action_controller.perform_caching` to `true` in
+the relevant `config/environments/*.rb` file:
 
 ```ruby
 config.action_controller.perform_caching = true
 ```
 
+NOTE: Changing the value of `config.action_controller.perform_caching` will
+only have an effect on the caching provided by the Action Controller component.
+For instance, it will not impact low-level caching, that we address
+[below](#low-level-caching).
+
 ### Page Caching
 
-Page caching is a Rails mechanism which allows the request for a generated page to be fulfilled by the webserver (i.e. Apache or NGINX), without ever having to go through the Rails stack at all. Obviously, this is super-fast. Unfortunately, it can't be applied to every situation (such as pages that need authentication) and since the webserver is literally just serving a file from the filesystem, cache expiration is an issue that needs to be dealt with.
+Page caching is a Rails mechanism which allows the request for a generated page
+to be fulfilled by the webserver (i.e. Apache or NGINX) without having to go
+through the entire Rails stack. While this is super fast it can't be applied to
+every situation (such as pages that need authentication). Also, because the
+webserver is serving a file directly from the filesystem you will need to
+implement cache expiration.
 
-INFO: Page Caching has been removed from Rails 4. See the [actionpack-page_caching gem](https://github.com/rails/actionpack-page_caching). See [DHH's key-based cache expiration overview](http://signalvnoise.com/posts/3113-how-key-based-cache-expiration-works) for the newly-preferred method.
+INFO: Page Caching has been removed from Rails 4. See the [actionpack-page_caching gem](https://github.com/rails/actionpack-page_caching).
 
 ### Action Caching
 
@@ -42,109 +67,217 @@ INFO: Action Caching has been removed from Rails 4. See the [actionpack-action_c
 
 ### Fragment Caching
 
-Life would be perfect if we could get away with caching the entire contents of a page or action and serving it out to the world. Unfortunately, dynamic web applications usually build pages with a variety of components not all of which have the same caching characteristics. In order to address such a dynamically created page where different parts of the page need to be cached and expired differently, Rails provides a mechanism called Fragment Caching.
+Dynamic web applications usually build pages with a variety of components not
+all of which have the same caching characteristics. When different parts of the
+page need to be cached and expired separately you can use Fragment Caching.
 
 Fragment Caching allows a fragment of view logic to be wrapped in a cache block and served out of the cache store when the next request comes in.
 
-As an example, if you wanted to show all the orders placed on your website in real time and didn't want to cache that part of the page, but did want to cache the part of the page which lists all products available, you could use this piece of code:
+For example, if you wanted to cache each product on a page, you could use this
+code:
 
 ```html+erb
-<% Order.find_recent.each do |o| %>
-  <%= o.buyer.name %> bought <%= o.product.name %>
-<% end %>
-
-<% cache do %>
-  All available products:
-  <% Product.all.each do |p| %>
-    <%= link_to p.name, product_url(p) %>
+<% @products.each do |product| %>
+  <% cache product do %>
+    <%= render product %>
   <% end %>
 <% end %>
 ```
 
-The cache block in our example will bind to the action that called it and is written out to the same place as the Action Cache, which means that if you want to cache multiple fragments per action, you should provide an `action_suffix` to the cache call:
+When your application receives its first request to this page, Rails will write
+a new cache entry with a unique key. A key looks something like this:
 
-```html+erb
-<% cache(action: 'recent', action_suffix: 'all_products') do %>
-  All available products:
+```
+views/products/1-201505056193031061005000/bea67108094918eeba42cd4a6e786901
 ```
 
-and you can expire it using the `expire_fragment` method, like so:
+The number in the middle is the `product_id` followed by the timestamp value in
+the `updated_at` attribute of the product record. Rails uses the timestamp value
+to make sure it is not serving stale data. If the value of `updated_at` has
+changed, a new key will be generated. Then Rails will write a new cache to that
+key, and the old cache written to the old key will never be used again. This is
+called key-based expiration.
 
-```ruby
-expire_fragment(controller: 'products', action: 'recent', action_suffix: 'all_products')
-```
+Cache fragments will also be expired when the view fragment changes (e.g., the
+HTML in the view changes). The string of characters at the end of the key is a
+template tree digest. It is an md5 hash computed based on the contents of the
+view fragment you are caching. If you change the view fragment, the md5 hash
+will change, expiring the existing file.
 
-If you don't want the cache block to bind to the action that called it, you can also use globally keyed fragments by calling the `cache` method with a key:
+TIP: Cache stores like Memcached will automatically delete old cache files.
+
+If you want to cache a fragment under certain conditions, you can use
+`cache_if` or `cache_unless`:
 
 ```erb
-<% cache('all_available_products') do %>
-  All available products:
+<% cache_if admin?, product do %>
+  <%= render product %>
 <% end %>
 ```
 
-This fragment is then available to all actions in the `ProductsController` using the key and can be expired the same way:
+#### Collection caching
 
-```ruby
-expire_fragment('all_available_products')
-```
-If you want to avoid expiring the fragment manually, whenever an action updates a product, you can define a helper method:
+The `render` helper can also cache individual templates rendered for a collection.
+It can even one up the previous example with `each` by reading all cache
+templates at once instead of one by one. This is done automatically if the template
+rendered by the collection includes a `cache` call. Take a collection that renders
+a `products/_product.html.erb` partial for each element:
 
 ```ruby
-module ProductsHelper
-  def cache_key_for_products
-    count          = Product.count
-    max_updated_at = Product.maximum(:updated_at).try(:utc).try(:to_s, :number)
-    "products/all-#{count}-#{max_updated_at}"
-  end
-end
+render products
 ```
 
-This method generates a cache key that depends on all products and can be used in the view:
+If `products/_product.html.erb` starts with a `cache` call like so:
 
-```erb
-<% cache(cache_key_for_products) do %>
-  All available products:
+```html+erb
+<% cache product do %>
+  <%= product.name %>
 <% end %>
 ```
 
-If you want to cache a fragment under certain conditions, you can use `cache_if` or `cache_unless`
+All the cached templates from previous renders will be fetched at once with much
+greater speed. There's more info on how to make your templates [eligible for
+collection caching](http://api.rubyonrails.org/classes/ActionView/Template/Handlers/ERB.html#method-i-resource_cache_call_pattern).
+
+### Russian Doll Caching
+
+You may want to nest cached fragments inside other cached fragments. This is
+called Russian doll caching.
+
+The advantage of Russian doll caching is that if a single product is updated,
+all the other inner fragments can be reused when regenerating the outer
+fragment.
+
+As explained in the previous section, a cached file will expire if the value of
+`updated_at` changes for a record on which the cached file directly depends.
+However, this will not expire any cache the fragment is nested within.
+
+For example, take the following view:
 
 ```erb
-<% cache_if (condition, cache_key_for_products) do %>
-  All available products:
+<% cache product do %>
+  <%= render product.games %>
 <% end %>
 ```
 
-You can also use an Active Record model as the cache key:
+Which in turn renders this view:
 
 ```erb
-<% Product.all.each do |p| %>
-  <% cache(p) do %>
-    <%= link_to p.name, product_url(p) %>
-  <% end %>
+<% cache game do %>
+  <%= render game %>
 <% end %>
 ```
 
-Behind the scenes, a method called `cache_key` will be invoked on the model and it returns a string like `products/23-20130109142513`. The cache key includes the model name, the id and finally the updated_at timestamp. Thus it will automatically generate a new fragment when the product is updated because the key changes.
+If any attribute of game is changed, the `updated_at` value will be set to the
+current time, thereby expiring the cache. However, because `updated_at`
+will not be changed for the product object, that cache will not be expired and
+your app will serve stale data. To fix this, we tie the models together with
+the `touch` method:
+
+```ruby
+class Product < ActiveRecord::Base
+  has_many :games
+end
+
+class Game < ActiveRecord::Base
+  belongs_to :product, touch: true
+end
+```
+
+With `touch` set to true, any action which changes `updated_at` for a game
+record will also change it for the associated product, thereby expiring the
+cache.
 
-You can also combine the two schemes which is called "Russian Doll Caching":
+### Managing dependencies
 
-```erb
-<% cache(cache_key_for_products) do %>
-  All available products:
-  <% Product.all.each do |p| %>
-    <% cache(p) do %>
-      <%= link_to p.name, product_url(p) %>
-    <% end %>
-  <% end %>
+In order to correctly invalidate the cache, you need to properly define the
+caching dependencies. Rails is clever enough to handle common cases so you don't
+have to specify anything. However, sometimes, when you're dealing with custom
+helpers for instance, you need to explicitly define them.
+
+#### Implicit dependencies
+
+Most template dependencies can be derived from calls to `render` in the template
+itself. Here are some examples of render calls that `ActionView::Digestor` knows
+how to decode:
+
+```ruby
+render partial: "comments/comment", collection: commentable.comments
+render "comments/comments"
+render 'comments/comments'
+render('comments/comments')
+
+render "header" => render("comments/header")
+
+render(@topic)         => render("topics/topic")
+render(topics)         => render("topics/topic")
+render(message.topics) => render("topics/topic")
+```
+
+On the other hand, some calls need to be changed to make caching work properly.
+For instance, if you're passing a custom collection, you'll need to change:
+
+```ruby
+render @project.documents.where(published: true)
+```
+
+to:
+
+```ruby
+render partial: "documents/document", collection: @project.documents.where(published: true)
+```
+
+#### Explicit dependencies
+
+Sometimes you'll have template dependencies that can't be derived at all. This
+is typically the case when rendering happens in helpers. Here's an example:
+
+```html+erb
+<%= render_sortable_todolists @project.todolists %>
+```
+
+You'll need to use a special comment format to call those out:
+
+```html+erb
+<%# Template Dependency: todolists/todolist %>
+<%= render_sortable_todolists @project.todolists %>
+```
+
+In some cases, like a single table inheritance setup, you might have a bunch of
+explicit dependencies. Instead of writing every template out, you can use a
+wildcard to match any template in a directory:
+
+```html+erb
+<%# Template Dependency: events/* %>
+<%= render_categorizable_events @person.events %>
+```
+
+As for collection caching, if the partial template doesn't start with a clean
+cache call, you can still benefit from collection caching by adding a special
+comment format anywhere in the template, like:
+
+```html+erb
+<%# Template Collection: notification %>
+<% my_helper_that_calls_cache(some_arg, notification) do %>
+  <%= notification.name %>
 <% end %>
 ```
 
-It's called "Russian Doll Caching" because it nests multiple fragments. The advantage is that if a single product is updated, all the other inner fragments can be reused when regenerating the outer fragment.
+#### External dependencies
+
+If you use a helper method, for example, inside a cached block and you then update
+that helper, you'll have to bump the cache as well. It doesn't really matter how
+you do it, but the md5 of the template file must change. One recommendation is to
+simply be explicit in a comment, like:
+
+```html+erb
+<%# Helper Dependency Updated: Jul 28, 2015 at 7pm %>
+<%= some_helper_method(person) %>
+```
 
 ### Low-Level Caching
 
-Sometimes you need to cache a particular value or query result, instead of caching view fragments. Rails caching mechanism works great for storing __any__ kind of information.
+Sometimes you need to cache a particular value or query result instead of caching view fragments. Rails' caching mechanism works great for storing __any__ kind of information.
 
 The most efficient way to implement low-level caching is using the `Rails.cache.fetch` method. This method does both reading and writing to the cache. When passed only a single argument, the key is fetched and value from the cache is returned. If a block is passed, the result of the block will be cached to the given key and the result is returned.
 
@@ -160,11 +293,14 @@ class Product < ActiveRecord::Base
 end
 ```
 
-NOTE: Notice that in this example we used `cache_key` method, so the resulting cache-key will be something like `products/233-20140225082222765838000/competing_price`. `cache_key` generates a string based on the model’s `id` and `updated_at` attributes. This is a common convention and has the benefit of invalidating the cache whenever the product is updated. In general, when you use low-level caching for instance level information, you need to generate a cache key.
+NOTE: Notice that in this example we used the `cache_key` method, so the resulting cache-key will be something like `products/233-20140225082222765838000/competing_price`. `cache_key` generates a string based on the model’s `id` and `updated_at` attributes. This is a common convention and has the benefit of invalidating the cache whenever the product is updated. In general, when you use low-level caching for instance level information, you need to generate a cache key.
 
 ### SQL Caching
 
-Query caching is a Rails feature that caches the result set returned by each query so that if Rails encounters the same query again for that request, it will use the cached result set as opposed to running the query against the database again.
+Query caching is a Rails feature that caches the result set returned by each
+query. If Rails encounters the same query again for that request, it will use
+the cached result set as opposed to running the query against the database
+again.
 
 For example:
 
@@ -186,21 +322,25 @@ end
 
 The second time the same query is run against the database, it's not actually going to hit the database. The first time the result is returned from the query it is stored in the query cache (in memory) and the second time it's pulled from memory.
 
-However, it's important to note that query caches are created at the start of an action and destroyed at the end of that action and thus persist only for the duration of the action. If you'd like to store query results in a more persistent fashion, you can in Rails by using low level caching.
+However, it's important to note that query caches are created at the start of
+an action and destroyed at the end of that action and thus persist only for the
+duration of the action. If you'd like to store query results in a more
+persistent fashion, you can with low level caching.
 
 Cache Stores
 ------------
 
-Rails provides different stores for the cached data created by **action** and **fragment** caches.
-
-TIP: Page caches are always stored on disk.
+Rails provides different stores for the cached data (apart from SQL and page
+caching).
 
 ### Configuration
 
-You can set up your application's default cache store by calling `config.cache_store=` in the Application definition inside your `config/application.rb` file or in an Application.configure block in an environment specific configuration file (i.e. `config/environments/*.rb`). The first argument will be the cache store to use and the rest of the argument will be passed as arguments to the cache store constructor.
+You can set up your application's default cache store by setting the
+`config.cache_store` configuration option. Other parameters can be passed as
+arguments to the cache store's constructor:
 
 ```ruby
-config.cache_store = :memory_store
+config.cache_store = :memory_store, { size: 64.megabytes }
 ```
 
 NOTE: Alternatively, you can call `ActionController::Base.cache_store` outside of a configuration block.
@@ -219,21 +359,42 @@ There are some common options used by all cache implementations. These can be pa
 
 * `:compress` - This option can be used to indicate that compression should be used in the cache. This can be useful for transferring large cache entries over a slow network.
 
-* `:compress_threshold` - This options is used in conjunction with the `:compress` option to indicate a threshold under which cache entries should not be compressed. This defaults to 16 kilobytes.
+* `:compress_threshold` - This option is used in conjunction with the `:compress` option to indicate a threshold under which cache entries should not be compressed. This defaults to 16 kilobytes.
 
 * `:expires_in` - This option sets an expiration time in seconds for the cache entry when it will be automatically removed from the cache.
 
 * `:race_condition_ttl` - This option is used in conjunction with the `:expires_in` option. It will prevent race conditions when cache entries expire by preventing multiple processes from simultaneously regenerating the same entry (also known as the dog pile effect). This option sets the number of seconds that an expired entry can be reused while a new value is being regenerated. It's a good practice to set this value if you use the `:expires_in` option.
 
+#### Custom Cache Stores
+
+You can create your own custom cache store by simply extending
+`ActiveSupport::Cache::Store` and implementing the appropriate methods. This way,
+you can swap in any number of caching technologies into your Rails application.
+
+To use a custom cache store, simply set the cache store to a new instance of your
+custom class.
+
+```ruby
+config.cache_store = MyCacheStore.new
+```
+
 ### ActiveSupport::Cache::MemoryStore
 
-This cache store keeps entries in memory in the same Ruby process. The cache store has a bounded size specified by the `:size` options to the initializer (default is 32Mb). When the cache exceeds the allotted size, a cleanup will occur and the least recently used entries will be removed.
+This cache store keeps entries in memory in the same Ruby process. The cache
+store has a bounded size specified by sending the `:size` option to the
+initializer (default is 32Mb). When the cache exceeds the allotted size, a
+cleanup will occur and the least recently used entries will be removed.
 
 ```ruby
 config.cache_store = :memory_store, { size: 64.megabytes }
 ```
 
-If you're running multiple Ruby on Rails server processes (which is the case if you're using mongrel_cluster or Phusion Passenger), then your Rails server process instances won't be able to share cache data with each other. This cache store is not appropriate for large application deployments, but can work well for small, low traffic sites with only a couple of server processes or for development and test environments.
+If you're running multiple Ruby on Rails server processes (which is the case
+if you're using mongrel_cluster or Phusion Passenger), then your Rails server
+process instances won't be able to share cache data with each other. This cache
+store is not appropriate for large application deployments. However, it can
+work well for small, low traffic sites with only a couple of server processes,
+as well as development and test environments.
 
 ### ActiveSupport::Cache::FileStore
 
@@ -243,9 +404,13 @@ This cache store uses the file system to store entries. The path to the director
 config.cache_store = :file_store, "/path/to/cache/directory"
 ```
 
-With this cache store, multiple server processes on the same host can share a cache. Servers processes running on different hosts could share a cache by using a shared file system, but that set up would not be ideal and is not recommended. The cache store is appropriate for low to medium traffic sites that are served off one or two hosts.
+With this cache store, multiple server processes on the same host can share a
+cache. The cache store is appropriate for low to medium traffic sites that are
+served off one or two hosts. Server processes running on different hosts could
+share a cache by using a shared file system, but that setup is not recommended.
 
-Note that the cache will grow until the disk is full unless you periodically clear out old entries.
+As the cache will grow until the disk is full, it is recommended to
+periodically clear out old entries.
 
 This is the default cache store implementation.
 
@@ -253,65 +418,32 @@ This is the default cache store implementation.
 
 This cache store uses Danga's `memcached` server to provide a centralized cache for your application. Rails uses the bundled `dalli` gem by default. This is currently the most popular cache store for production websites. It can be used to provide a single, shared cache cluster with very high performance and redundancy.
 
-When initializing the cache, you need to specify the addresses for all memcached servers in your cluster. If none is specified, it will assume memcached is running on the local host on the default port, but this is not an ideal set up for larger sites.
+When initializing the cache, you need to specify the addresses for all
+memcached servers in your cluster. If none are specified, it will assume
+memcached is running on localhost on the default port, but this is not an ideal
+setup for larger sites.
 
-The `write` and `fetch` methods on this cache accept two additional options that take advantage of features specific to memcached. You can specify `:raw` to send a value directly to the server with no serialization. The value must be a string or number. You can use memcached direct operation like `increment` and `decrement` only on raw values. You can also specify `:unless_exist` if you don't want memcached to overwrite an existing entry.
+The `write` and `fetch` methods on this cache accept two additional options that take advantage of features specific to memcached. You can specify `:raw` to send a value directly to the server with no serialization. The value must be a string or number. You can use memcached direct operations like `increment` and `decrement` only on raw values. You can also specify `:unless_exist` if you don't want memcached to overwrite an existing entry.
 
 ```ruby
 config.cache_store = :mem_cache_store, "cache-1.example.com", "cache-2.example.com"
 ```
 
-### ActiveSupport::Cache::EhcacheStore
-
-If you are using JRuby you can use Terracotta's Ehcache as the cache store for your application. Ehcache is an open source Java cache that also offers an enterprise version with increased scalability, management, and commercial support. You must first install the jruby-ehcache-rails3 gem (version 1.1.0 or later) to use this cache store.
-
-```ruby
-config.cache_store = :ehcache_store
-```
-
-When initializing the cache, you may use the `:ehcache_config` option to specify the Ehcache config file to use (where the default is "ehcache.xml" in your Rails config directory), and the :cache_name option to provide a custom name for your cache (the default is rails_cache).
-
-In addition to the standard `:expires_in` option, the `write` method on this cache can also accept the additional `:unless_exist` option, which will cause the cache store to use Ehcache's `putIfAbsent` method instead of `put`, and therefore will not overwrite an existing entry. Additionally, the `write` method supports all of the properties exposed by the [Ehcache Element class](http://ehcache.org/apidocs/net/sf/ehcache/Element.html) , including:
-
-| Property                    | Argument Type       | Description                                                 |
-| --------------------------- | ------------------- | ----------------------------------------------------------- |
-| elementEvictionData         | ElementEvictionData | Sets this element's eviction data instance.                 |
-| eternal                     | boolean             | Sets whether the element is eternal.                        |
-| timeToIdle, tti             | int                 | Sets time to idle                                           |
-| timeToLive, ttl, expires_in | int                 | Sets time to Live                                           |
-| version                     | long                | Sets the version attribute of the ElementAttributes object. |
-
-These options are passed to the `write` method as Hash options using either camelCase or underscore notation, as in the following examples:
-
-```ruby
-Rails.cache.write('key', 'value', time_to_idle: 60.seconds, timeToLive: 600.seconds)
-caches_action :index, expires_in: 60.seconds, unless_exist: true
-```
-
-For more information about Ehcache, see [http://ehcache.org/](http://ehcache.org/) .
-For more information about Ehcache for JRuby and Rails, see [http://ehcache.org/documentation/jruby.html](http://ehcache.org/documentation/jruby.html)
-
 ### ActiveSupport::Cache::NullStore
 
-This cache store implementation is meant to be used only in development or test environments and it never stores anything. This can be very useful in development when you have code that interacts directly with `Rails.cache`, but caching may interfere with being able to see the results of code changes. With this cache store, all `fetch` and `read` operations will result in a miss.
+This cache store implementation is meant to be used only in development or test environments and it never stores anything. This can be very useful in development when you have code that interacts directly with `Rails.cache` but caching may interfere with being able to see the results of code changes. With this cache store, all `fetch` and `read` operations will result in a miss.
 
 ```ruby
 config.cache_store = :null_store
 ```
 
-### Custom Cache Stores
-
-You can create your own custom cache store by simply extending `ActiveSupport::Cache::Store` and implementing the appropriate methods. In this way, you can swap in any number of caching technologies into your Rails application.
-
-To use a custom cache store, simple set the cache store to a new instance of the class.
-
-```ruby
-config.cache_store = MyCacheStore.new
-```
-
-### Cache Keys
+Cache Keys
+----------
 
-The keys used in a cache can be any object that responds to either `:cache_key` or to `:to_param`. You can implement the `:cache_key` method on your classes if you need to generate custom keys. Active Record will generate keys based on the class name and record id.
+The keys used in a cache can be any object that responds to either `cache_key` or
+`to_param`. You can implement the `cache_key` method on your classes if you need
+to generate custom keys. Active Record will generate keys based on the class name
+and record id.
 
 You can use Hashes and Arrays of values as cache keys.
 
@@ -320,7 +452,12 @@ You can use Hashes and Arrays of values as cache keys.
 Rails.cache.read(site: "mysite", owners: [owner_1, owner_2])
 ```
 
-The keys you use on `Rails.cache` will not be the same as those actually used with the storage engine. They may be modified with a namespace or altered to fit technology backend constraints. This means, for instance, that you can't save values with `Rails.cache` and then try to pull them out with the `memcache-client` gem. However, you also don't need to worry about exceeding the memcached size limit or violating syntax rules.
+The keys you use on `Rails.cache` will not be the same as those actually used with
+the storage engine. They may be modified with a namespace or altered to fit
+technology backend constraints. This means, for instance, that you can't save
+values with `Rails.cache` and then try to pull them out with the `dalli` gem.
+However, you also don't need to worry about exceeding the memcached size limit or
+violating syntax rules.
 
 Conditional GET support
 -----------------------
@@ -353,7 +490,7 @@ class ProductsController < ApplicationController
 end
 ```
 
-Instead of an options hash, you can also simply pass in a model, Rails will use the `updated_at` and `cache_key` methods for setting `last_modified` and `etag`:
+Instead of an options hash, you can also simply pass in a model. Rails will use the `updated_at` and `cache_key` methods for setting `last_modified` and `etag`:
 
 ```ruby
 class ProductsController < ApplicationController
@@ -383,3 +520,9 @@ class ProductsController < ApplicationController
   end
 end
 ```
+
+References
+----------
+
+* [DHH's article on key-based expiration](https://signalvnoise.com/posts/3113-how-key-based-cache-expiration-works)
+* [Ryan Bates' Railscast on cache digests](http://railscasts.com/episodes/387-cache-digests)
diff --git a/guides/source/command_line.md b/guides/source/command_line.md
index 78f26ccefa..e85f9fc9c6 100644
--- a/guides/source/command_line.md
+++ b/guides/source/command_line.md
@@ -64,10 +64,10 @@ $ cd commandsapp
 $ bin/rails server
 => Booting WEBrick
 => Rails 5.0.0 application starting in development on http://localhost:3000
-=> Call with -d to detach
+=> Run `rails server -h` for more startup options
 => Ctrl-C to shutdown server
 [2013-08-07 02:00:01] INFO  WEBrick 1.3.1
-[2013-08-07 02:00:01] INFO  ruby 2.0.0 (2013-06-27) [x86_64-darwin11.2.0]
+[2013-08-07 02:00:01] INFO  ruby 2.2.2 (2015-06-27) [x86_64-darwin11.2.0]
 [2013-08-07 02:00:01] INFO  WEBrick::HTTPServer#start: pid=69680 port=3000
 ```
 
@@ -260,7 +260,13 @@ $ bin/rake db:migrate
 ==  CreateHighScores: migrated (0.0019s) ======================================
 ```
 
-INFO: Let's talk about unit tests. Unit tests are code that tests and makes assertions about code. In unit testing, we take a little part of code, say a method of a model, and test its inputs and outputs. Unit tests are your friend. The sooner you make peace with the fact that your quality of life will drastically increase when you unit test your code, the better. Seriously. We'll make one in a moment.
+INFO: Let's talk about unit tests. Unit tests are code that tests and makes assertions 
+about code. In unit testing, we take a little part of code, say a method of a model, 
+and test its inputs and outputs. Unit tests are your friend. The sooner you make 
+peace with the fact that your quality of life will drastically increase when you unit 
+test your code, the better. Seriously. Please visit 
+[the testing guide](http://guides.rubyonrails.org/testing.html) for an in-depth 
+look at unit testing.
 
 Let's see the interface Rails created for us.
 
@@ -338,6 +344,12 @@ You can specify the environment in which the `runner` command should operate usi
 $ bin/rails runner -e staging "Model.long_running_method"
 ```
 
+You can even execute ruby code written in a file with runner.
+
+```bash
+$ bin/rails runner lib/code_to_be_run.rb
+```
+
 ### `rails destroy`
 
 Think of `destroy` as the opposite of `generate`. It'll figure out what generate did, and undo it.
@@ -396,11 +408,11 @@ INFO: You can also use `rake -T`  to get the list of tasks.
 $ bin/rake about
 About your application's environment
 Rails version             5.0.0
-Ruby version              2.2.0 (x86_64-linux)
-RubyGems version          2.4.5
+Ruby version              2.2.2 (x86_64-linux)
+RubyGems version          2.4.6
 Rack version              1.6
 JavaScript Runtime        Node.js (V8)
-Middleware                Rack::Sendfile, ActionDispatch::Static, Rack::Lock, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x007ffd131a7c88>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, Rack::Head, Rack::ConditionalGet, Rack::ETag
+Middleware                Rack::Sendfile, ActionDispatch::Static, Rack::Lock, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x007ffd131a7c88>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, Rack::Head, Rack::ConditionalGet, Rack::ETag
 Application root          /home/foobar/commandsapp
 Environment               development
 Database adapter          sqlite3
@@ -417,15 +429,7 @@ If you want to clear `public/assets` completely, you can use `rake assets:clobbe
 
 The most common tasks of the `db:` Rake namespace are `migrate` and `create`, and it will pay off to try out all of the migration rake tasks (`up`, `down`, `redo`, `reset`). `rake db:version` is useful when troubleshooting, telling you the current version of the database.
 
-More information about migrations can be found in the [Migrations](migrations.html) guide.
-
-### `doc`
-
-The `doc:` namespace has the tools to generate documentation for your app, API documentation, guides. Documentation can also be stripped which is mainly useful for slimming your codebase, like if you're writing a Rails application for an embedded platform.
-
-* `rake doc:app` generates documentation for your application in `doc/app`.
-* `rake doc:guides` generates Rails guides in `doc/guides`.
-* `rake doc:rails` generates API documentation for Rails in `doc/api`.
+More information about migrations can be found in the [Migrations](active_record_migrations.html) guide.
 
 ### `notes`
 
@@ -472,7 +476,7 @@ app/models/article.rb:
 
 NOTE. When using specific annotations and custom annotations, the annotation name (FIXME, BUG etc) is not displayed in the output lines.
 
-By default, `rake notes` will look in the `app`, `config`, `lib`, `bin` and `test` directories. If you would like to search other directories, you can provide them as a comma separated list in an environment variable `SOURCE_ANNOTATION_DIRECTORIES`.
+By default, `rake notes` will look in the `app`, `config`, `db`, `lib` and `test` directories. If you would like to search other directories, you can provide them as a comma separated list in an environment variable `SOURCE_ANNOTATION_DIRECTORIES`.
 
 ```bash
 $ export SOURCE_ANNOTATION_DIRECTORIES='spec,vendor'
@@ -528,8 +532,8 @@ end
 To pass arguments to your custom rake task:
 
 ```ruby
-task :task_name, [:arg_1] => [:pre_1, :pre_2] do |t, args|
-  # You can use args from here
+task :task_name, [:arg_1] => [:prerequisite_1, :prerequisite_2] do |task, args|
+  argument_1 = args.arg_1
 end
 ```
 
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 9c0f2ddc8a..e2125cae2e 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -88,8 +88,6 @@ application. Accepts a valid week day symbol (e.g. `:monday`).
     end
     ```
 
-* `config.dependency_loading` is a flag that allows you to disable constant autoloading setting it to false. It only has effect if `config.cache_classes` is true, which it is by default in production mode.
-
 * `config.eager_load` when true, eager loads all registered `config.eager_load_namespaces`. This includes your application, engines, Rails frameworks and any other registered namespace.
 
 * `config.eager_load_namespaces` registers namespaces that are eager loaded when `config.eager_load` is true. All namespaces in the list must respond to the `eager_load!` method.
@@ -110,9 +108,11 @@ numbers. New applications filter out passwords by adding the following `config.f
 
 * `config.log_formatter` defines the formatter of the Rails logger. This option defaults to an instance of `ActiveSupport::Logger::SimpleFormatter` for all modes except production, where it defaults to `Logger::Formatter`.
 
-* `config.log_level` defines the verbosity of the Rails logger. This option defaults to `:debug` for all environments. The available log levels are: :debug, :info, :warn, :error, :fatal, and :unknown.
+* `config.log_level` defines the verbosity of the Rails logger. This option
+defaults to `:debug` for all environments. The available log levels are: `:debug`,
+`:info`, `:warn`, `:error`, `:fatal`, and `:unknown`.
 
-* `config.log_tags` accepts a list of methods that the `request` object responds to. This makes it easy to tag log lines with debug information like subdomain and request id - both very helpful in debugging multi-user production applications.
+* `config.log_tags` accepts a list of: methods that the `request` object responds to, a `Proc` that accepts the `request` object, or something that responds to `to_s`. This makes it easy to tag log lines with debug information like subdomain and request id - both very helpful in debugging multi-user production applications.
 
 * `config.logger` accepts a logger conforming to the interface of Log4r or the default Ruby `Logger` class. Defaults to an instance of `ActiveSupport::Logger`.
 
@@ -161,8 +161,6 @@ pipeline is enabled. It is set to true by default.
 
 * `config.assets.cache_store` defines the cache store that Sprockets will use. The default is the Rails file store.
 
-* `config.assets.version` is an option string that is used in MD5 hash generation. This can be changed to force all files to be recompiled.
-
 * `config.assets.compile` is a boolean that can be used to turn on live Sprockets compilation in production.
 
 * `config.assets.logger` accepts a logger conforming to the interface of Log4r or the default Ruby `Logger` class. Defaults to the same configured at `config.logger`. Setting `config.assets.logger` to false will turn off served assets logging.
@@ -183,15 +181,17 @@ The full set of methods that can be used in this block are as follows:
 * `assets` allows to create assets on generating a scaffold. Defaults to `true`.
 * `force_plural` allows pluralized model names. Defaults to `false`.
 * `helper` defines whether or not to generate helpers. Defaults to `true`.
-* `integration_tool` defines which integration tool to use. Defaults to `nil`.
+* `integration_tool` defines which integration tool to use to generate integration tests. Defaults to `:test_unit`.
 * `javascripts` turns on the hook for JavaScript files in generators. Used in Rails for when the `scaffold` generator is run. Defaults to `true`.
-* `javascript_engine` configures the engine to be used (for eg. coffee) when generating assets. Defaults to `nil`.
+* `javascript_engine` configures the engine to be used (for eg. coffee) when generating assets. Defaults to `:js`.
 * `orm` defines which orm to use. Defaults to `false` and will use Active Record by default.
 * `resource_controller` defines which generator to use for generating a controller when using `rails generate resource`. Defaults to `:controller`.
+* `resource_route` defines whether a resource route definition should be generated
+  or not. Defaults to `true`.
 * `scaffold_controller` different from `resource_controller`, defines which generator to use for generating a _scaffolded_ controller when using `rails generate scaffold`. Defaults to `:scaffold_controller`.
 * `stylesheets` turns on the hook for stylesheets in generators. Used in Rails for when the `scaffold` generator is run, but this hook can be used in other generates as well. Defaults to `true`.
 * `stylesheet_engine` configures the stylesheet engine (for eg. sass) to be used when generating assets. Defaults to `:css`.
-* `test_framework` defines which test framework to use. Defaults to `false` and will use Test::Unit by default.
+* `test_framework` defines which test framework to use. Defaults to `false` and will use Minitest by default.
 * `template_engine` defines which template engine to use, such as ERB or Haml. Defaults to `:erb`.
 
 ### Configuring Middleware
@@ -199,7 +199,7 @@ The full set of methods that can be used in this block are as follows:
 Every Rails application comes with a standard set of middleware which it uses in this order in the development environment:
 
 * `ActionDispatch::SSL` forces every request to be under HTTPS protocol. Will be available if `config.force_ssl` is set to `true`. Options passed to this can be configured by using `config.ssl_options`.
-* `ActionDispatch::Static` is used to serve static assets. Disabled if `config.serve_static_files` is `false`.
+* `ActionDispatch::Static` is used to serve static assets. Disabled if `config.serve_static_files` is `false`. Set `config.static_index` if you need to serve a static directory index file that is not named `index`. For example, to serve `main.html` instead of `index.html` for directory requests, set `config.static_index` to `"main"`.
 * `Rack::Lock` wraps the app in mutex so it can only be called by a single thread at a time. Only enabled when `config.cache_classes` is `false`.
 * `ActiveSupport::Cache::Strategy::LocalCache` serves as a basic memory backed cache. This cache is not thread safe and is intended only for serving as a temporary memory cache for a single thread.
 * `Rack::Runtime` sets an `X-Runtime` header, containing the time (in seconds) taken to execute the request.
@@ -214,7 +214,6 @@ Every Rails application comes with a standard set of middleware which it uses in
 * `ActionDispatch::Cookies` sets cookies for the request.
 * `ActionDispatch::Session::CookieStore` is responsible for storing the session in cookies. An alternate middleware can be used for this by changing the `config.action_controller.session_store` to an alternate value. Additionally, options passed to this can be configured by using `config.action_controller.session_options`.
 * `ActionDispatch::Flash` sets up the `flash` keys. Only available if `config.action_controller.session_store` is set to a value.
-* `ActionDispatch::ParamsParser` parses out parameters from the request into `params`.
 * `Rack::MethodOverride` allows the method to be overridden if `params[:_method]` is set. This is the middleware which supports the PATCH, PUT, and DELETE HTTP method types.
 * `Rack::Head` converts HEAD requests to GET requests and serves them as so.
 
@@ -245,7 +244,7 @@ config.middleware.swap ActionController::Failsafe, Lifo::Failsafe
 They can also be removed from the stack completely:
 
 ```ruby
-config.middleware.delete "Rack::MethodOverride"
+config.middleware.delete Rack::MethodOverride
 ```
 
 ### Configuring i18n
@@ -267,8 +266,8 @@ All these configuration options are delegated to the `I18n` library.
 * `config.active_record.logger` accepts a logger conforming to the interface of Log4r or the default Ruby Logger class, which is then passed on to any new database connections made. You can retrieve this logger by calling `logger` on either an Active Record model class or an Active Record model instance. Set to `nil` to disable logging.
 
 * `config.active_record.primary_key_prefix_type` lets you adjust the naming for primary key columns. By default, Rails assumes that primary key columns are named `id` (and this configuration option doesn't need to be set.) There are two other choices:
-** `:table_name` would make the primary key for the Customer class `customerid`
-** `:table_name_with_underscore` would make the primary key for the Customer class `customer_id`
+    * `:table_name` would make the primary key for the Customer class `customerid`
+    * `:table_name_with_underscore` would make the primary key for the Customer class `customer_id`
 
 * `config.active_record.table_name_prefix` lets you set a global string to be prepended to table names. If you set this to `northwest_`, then the Customer class will look for `northwest_customers` as its table. The default is an empty string.
 
@@ -286,7 +285,7 @@ All these configuration options are delegated to the `I18n` library.
 
 * `config.active_record.lock_optimistically` controls whether Active Record will use optimistic locking and is true by default.
 
-* `config.active_record.cache_timestamp_format` controls the format of the timestamp value in the cache key. Default is `:number`.
+* `config.active_record.cache_timestamp_format` controls the format of the timestamp value in the cache key. Default is `:nsec`.
 
 * `config.active_record.record_timestamps` is a boolean value which controls whether or not timestamping of `create` and `update` operations on a model occur. The default value is `true`.
 
@@ -300,6 +299,24 @@ All these configuration options are delegated to the `I18n` library.
   `config/environments/production.rb` which is generated by Rails. The
   default value is true if this configuration is not set.
 
+* `config.active_record.dump_schemas` controls which database schemas will be dumped when calling db:structure:dump.
+  The options are `:schema_search_path` (the default) which dumps any schemas listed in schema_search_path,
+  `:all` which always dumps all schemas regardless of the schema_search_path,
+  or a string of comma separated schemas.
+
+* `config.active_record.belongs_to_required_by_default` is a boolean value and
+  controls whether a record fails validation if `belongs_to` association is not
+  present.
+
+* `config.active_record.warn_on_records_fetched_greater_than` allows setting a
+  warning threshold for query result size. If the number of records returned
+  by a query exceeds the threshold, a warning is logged. This can be used to
+  identify queries which might be causing memory bloat.
+
+* `config.active_record.index_nested_attribute_errors` allows errors for nested
+  has_many relationships to be displayed with an index as well as the error.
+  Defaults to false.
+
 The MySQL adapter adds one additional configuration option:
 
 * `ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans` controls whether Active Record will consider all `tinyint(1)` columns in a MySQL database to be booleans and is true by default.
@@ -314,7 +331,7 @@ The schema dumper adds one additional configuration option:
 
 * `config.action_controller.asset_host` sets the host for the assets. Useful when CDNs are used for hosting assets rather than the application server itself.
 
-* `config.action_controller.perform_caching` configures whether the application should perform caching or not. Set to false in development mode, true in production.
+* `config.action_controller.perform_caching` configures whether the application should perform the caching features provided by the Action Controller component or not. Set to false in development mode, true in production.
 
 * `config.action_controller.default_static_extension` configures the extension used for cached pages. Defaults to `.html`.
 
@@ -402,7 +419,7 @@ encrypted cookies salt value. Defaults to `'signed encrypted cookie'`.
 
 `config.action_view` includes a small number of configuration settings:
 
-* `config.action_view.field_error_proc` provides an HTML generator for displaying errors that come from Active Record. The default is
+* `config.action_view.field_error_proc` provides an HTML generator for displaying errors that come from Active Model. The default is
 
     ```ruby
     Proc.new do |html_tag, instance|
@@ -410,13 +427,23 @@ encrypted cookies salt value. Defaults to `'signed encrypted cookie'`.
     end
     ```
 
-* `config.action_view.default_form_builder` tells Rails which form builder to use by default. The default is `ActionView::Helpers::FormBuilder`. If you want your form builder class to be loaded after initialization (so it's reloaded on each request in development), you can pass it as a `String`
+* `config.action_view.default_form_builder` tells Rails which form builder to
+  use by default. The default is `ActionView::Helpers::FormBuilder`. If you
+  want your form builder class to be loaded after initialization (so it's
+  reloaded on each request in development), you can pass it as a `String`.
 
 * `config.action_view.logger` accepts a logger conforming to the interface of Log4r or the default Ruby Logger class, which is then used to log information from Action View. Set to `nil` to disable logging.
 
 * `config.action_view.erb_trim_mode` gives the trim mode to be used by ERB. It defaults to `'-'`, which turns on trimming of tail spaces and newline when using `<%= -%>` or `<%= =%>`. See the [Erubis documentation](http://www.kuwata-lab.com/erubis/users-guide.06.html#topics-trimspaces) for more information.
 
-* `config.action_view.embed_authenticity_token_in_remote_forms` allows you to set the default behavior for `authenticity_token` in forms with `:remote => true`. By default it's set to false, which means that remote forms will not include `authenticity_token`, which is helpful when you're fragment-caching the form. Remote forms get the authenticity from the `meta` tag, so embedding is unnecessary unless you support browsers without JavaScript. In such case you can either pass `:authenticity_token => true` as a form option or set this config setting to `true`
+* `config.action_view.embed_authenticity_token_in_remote_forms` allows you to
+  set the default behavior for `authenticity_token` in forms with `remote:
+  true`. By default it's set to false, which means that remote forms will not
+  include `authenticity_token`, which is helpful when you're fragment-caching
+  the form. Remote forms get the authenticity from the `meta` tag, so embedding
+  is unnecessary unless you support browsers without JavaScript. In such case
+  you can either pass `authenticity_token: true` as a form option or set this
+  config setting to `true`.
 
 * `config.action_view.prefix_partial_path_with_controller_namespace` determines whether or not partials are looked up from a subdirectory in templates rendered from namespaced controllers. For example, consider a controller named `Admin::ArticlesController` which renders this template:
 
@@ -426,7 +453,11 @@ encrypted cookies salt value. Defaults to `'signed encrypted cookie'`.
 
     The default setting is `true`, which uses the partial at `/admin/articles/_article.erb`. Setting the value to `false` would render `/articles/_article.erb`, which is the same behavior as rendering from a non-namespaced controller such as `ArticlesController`.
 
-* `config.action_view.raise_on_missing_translations` determines whether an error should be raised for missing translations
+* `config.action_view.raise_on_missing_translations` determines whether an
+  error should be raised for missing translations.
+
+* `config.action_view.automatically_disable_submit_tag` determines whether
+  submit_tag should automatically disable on click, this defaults to true.
 
 ### Configuring Action Mailer
 
@@ -493,21 +524,24 @@ There are a number of settings available on `config.action_mailer`:
     config.action_mailer.show_previews = false
     ```
 
+* `config.action_mailer.deliver_later_queue_name` specifies the queue name for
+  mailers. By default this is `mailers`.
+
 ### Configuring Active Support
 
 There are a few configuration options available in Active Support:
 
 * `config.active_support.bare` enables or disables the loading of `active_support/all` when booting Rails. Defaults to `nil`, which means `active_support/all` is loaded.
 
-* `config.active_support.test_order` sets the order that test cases are executed. Possible values are `:sorted` and `:random`. Currently defaults to `:sorted`. In Rails 5.0, the default will be changed to `:random` instead.
+* `config.active_support.test_order` sets the order that test cases are executed. Possible values are `:random` and `:sorted`. This option is set to `:random` in `config/environments/test.rb` in newly-generated applications. If you have an application that does not specify a `test_order`, it will default to `:sorted`, *until* Rails 5.0, when the default will become `:random`.
 
-* `config.active_support.escape_html_entities_in_json` enables or disables the escaping of HTML entities in JSON serialization. Defaults to `false`.
+* `config.active_support.escape_html_entities_in_json` enables or disables the escaping of HTML entities in JSON serialization. Defaults to `true`.
 
 * `config.active_support.use_standard_json_time_format` enables or disables serializing dates to ISO 8601 format. Defaults to `true`.
 
 * `config.active_support.time_precision` sets the precision of JSON encoded time values. Defaults to `3`.
 
-* `config.active_support.halt_callback_chains_on_return_false` specifies whether ActiveRecord, ActiveModel and ActiveModel::Validations callback chains can be halted by returning `false` in a 'before' callback. Defaults to `true`.
+* `ActiveSupport.halt_callback_chains_on_return_false` specifies whether Active Record and Active Model callback chains can be halted by returning `false` in a 'before' callback. Defaults to `true`.
 
 * `ActiveSupport::Logger.silencer` is set to `false` to disable the ability to silence logging in a block. The default is `true`.
 
@@ -519,6 +553,58 @@ There are a few configuration options available in Active Support:
 
 * `ActiveSupport::Deprecation.silenced` sets whether or not to display deprecation warnings.
 
+### Configuring Active Job
+
+`config.active_job` provides the following configuration options:
+
+* `config.active_job.queue_adapter` sets the adapter for the queueing backend. The default adapter is `:inline` which will perform jobs immediately. For an up-to-date list of built-in adapters see the [ActiveJob::QueueAdapters API documentation](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html).
+
+    ```ruby
+    # Be sure to have the adapter's gem in your Gemfile
+    # and follow the adapter's specific installation
+    # and deployment instructions.
+    config.active_job.queue_adapter = :sidekiq
+    ```
+
+* `config.active_job.default_queue_name` can be used to change the default queue name. By default this is `"default"`.
+
+    ```ruby
+    config.active_job.default_queue_name = :medium_priority
+    ```
+
+* `config.active_job.queue_name_prefix` allows you to set an optional, non-blank, queue name prefix for all jobs. By default it is blank and not used.
+
+    The following configuration would queue the given job on the `production_high_priority` queue when run in production:
+
+    ```ruby
+    config.active_job.queue_name_prefix = Rails.env
+    ```
+
+    ```ruby
+    class GuestsCleanupJob < ActiveJob::Base
+      queue_as :high_priority
+      #....
+    end
+    ```
+
+* `config.active_job.queue_name_delimiter` has a default value of `'_'`. If `queue_name_prefix` is set, then `queue_name_delimiter` joins the prefix and the non-prefixed queue name.
+
+    The following configuration would queue the provided job on the `video_server.low_priority` queue:
+
+    ```ruby
+    # prefix must be set for delimiter to be used
+    config.active_job.queue_name_prefix = 'video_server'
+    config.active_job.queue_name_delimiter = '.'
+    ```
+
+    ```ruby
+    class EncoderJob < ActiveJob::Base
+      queue_as :low_priority
+      #....
+    end
+    ```
+
+* `config.active_job.logger` accepts a logger conforming to the interface of Log4r or the default Ruby Logger class, which is then used to log information from Active Job. You can retrieve this logger by calling `logger` on either an Active Job class or an Active Job instance. Set to `nil` to disable logging.
 
 ### Configuring a Database
 
@@ -561,7 +647,7 @@ TIP: You don't have to update the database configurations manually. If you look
 
 ### Connection Preference
 
-Since there are two ways to set your connection, via environment variable it is important to understand how the two can interact.
+Since there are two ways to configure your connection (using `config/database.yml` or using an environment variable) it is important to understand how they can interact.
 
 If you have an empty `config/database.yml` file but your `ENV['DATABASE_URL']` is present, then Rails will connect to the database via your environment variable:
 
@@ -817,15 +903,6 @@ server {
 
 Be sure to read the [NGINX documentation](http://nginx.org/en/docs/) for the most up-to-date information.
 
-#### Considerations when deploying to a subdirectory
-
-Deploying to a subdirectory in production has implications on various parts of
-Rails.
-
-* development environment:
-* testing environment:
-* serving static assets:
-* asset pipeline:
 
 Rails Environment Settings
 --------------------------
@@ -955,6 +1032,11 @@ Below is a comprehensive list of all the initializers found in Rails in the orde
 
 * `active_record.set_dispatch_hooks` Resets all reloadable connections to the database if `config.cache_classes` is set to `false`.
 
+* `active_job.logger` Sets `ActiveJob::Base.logger` - if it's not already set -
+  to `Rails.logger`.
+
+* `active_job.set_configs` Sets up Active Job by using the settings in `config.active_job` by `send`'ing the method names as setters to `ActiveJob::Base` and passing the values through.
+
 * `action_mailer.logger` Sets `ActionMailer::Base.logger` - if it's not already set - to `Rails.logger`.
 
 * `action_mailer.set_configs` Sets up Action Mailer by using the settings in `config.action_mailer` by `send`'ing the method names as setters to `ActionMailer::Base` and passing the values through.
@@ -973,8 +1055,6 @@ Below is a comprehensive list of all the initializers found in Rails in the orde
 
 * `load_environment_config` Loads the `config/environments` file for the current environment.
 
-* `append_asset_paths` Finds asset paths for the application and all attached railties and keeps a track of the available directories in `config.static_asset_paths`.
-
 * `prepend_helpers_path` Adds the directory `app/helpers` from the application, railties and engines to the lookup path for helpers for the application.
 
 * `load_config_initializers` Loads all Ruby files from `config/initializers` in the application, railties and engines. The files in this directory can be used to hold configuration settings that should be made after all of the frameworks are loaded.
@@ -1012,28 +1092,28 @@ development:
   timeout: 5000
 ```
 
-Since the connection pooling is handled inside of Active Record by default, all application servers (Thin, mongrel, Unicorn etc.) should behave the same. Initially, the database connection pool is empty and it will create additional connections as the demand for them increases, until it reaches the connection pool limit.
+Since the connection pooling is handled inside of Active Record by default, all application servers (Thin, mongrel, Unicorn etc.) should behave the same. The database connection pool is initially empty. As demand for connections increases it will create them until it reaches the connection pool limit.
 
-Any one request will check out a connection the first time it requires access to the database, after which it will check the connection back in, at the end of the request, meaning that the additional connection slot will be available again for the next request in the queue.
+Any one request will check out a connection the first time it requires access to the database. At the end of the request it will check the connection back in. This means that the additional connection slot will be available again for the next request in the queue.
 
 If you try to use more connections than are available, Active Record will block
-and wait for a connection from the pool. When it cannot get connection, a timeout
-error similar to given below will be thrown.
+you and wait for a connection from the pool. If it cannot get a connection, a
+timeout error similar to that given below will be thrown.
 
 ```ruby
-ActiveRecord::ConnectionTimeoutError - could not obtain a database connection within 5 seconds. The max pool size is currently 5; consider increasing it:
+ActiveRecord::ConnectionTimeoutError - could not obtain a database connection within 5.000 seconds (waited 5.000 seconds)
 ```
 
-If you get the above error, you might want to increase the size of connection
-pool by incrementing the `pool` option in `database.yml`
+If you get the above error, you might want to increase the size of the
+connection pool by incrementing the `pool` option in `database.yml`
 
-NOTE. If you are running in a multi-threaded environment, there could be a chance that several threads may be accessing multiple connections simultaneously. So depending on your current request load, you could very well have multiple threads contending for a limited amount of connections.
+NOTE. If you are running in a multi-threaded environment, there could be a chance that several threads may be accessing multiple connections simultaneously. So depending on your current request load, you could very well have multiple threads contending for a limited number of connections.
 
 
 Custom configuration
 --------------------
 
-You can configure your own code through the Rails configuration object with custom configuration. It works like this:
+You can configure your own code through the Rails configuration object with custom configuration under the `config.x` property. It works like this:
 
   ```ruby
   config.x.payment_processing.schedule = :daily
@@ -1049,3 +1129,23 @@ These configuration points are then available through the configuration object:
   Rails.configuration.x.super_debugger              # => true
   Rails.configuration.x.super_debugger.not_set      # => nil
   ```
+
+Search Engines Indexing
+-----------------------
+
+Sometimes, you may want to prevent some pages of your application to be visible
+on search sites like Google, Bing, Yahoo or Duck Duck Go. The robots that index
+these sites will first analyze the `http://your-site.com/robots.txt` file to
+know which pages it is allowed to index.
+
+Rails creates this file for you inside the `/public` folder. By default, it allows
+search engines to index all pages of your application. If you want to block
+indexing on all pages of you application, use this:
+
+```
+User-agent: *
+Disallow: /
+```
+
+To block just specific pages, it's necessary to use a more complex syntax. Learn
+it on the [official documentation](http://www.robotstxt.org/robotstxt.html).
diff --git a/guides/source/contributing_to_ruby_on_rails.md b/guides/source/contributing_to_ruby_on_rails.md
index 7381521658..6d689804a8 100644
--- a/guides/source/contributing_to_ruby_on_rails.md
+++ b/guides/source/contributing_to_ruby_on_rails.md
@@ -15,6 +15,9 @@ After reading this guide, you will know:
 
 Ruby on Rails is not "someone else's framework." Over the years, hundreds of people have contributed to Ruby on Rails ranging from a single character to massive architectural changes or significant documentation - all with the goal of making Ruby on Rails better for everyone. Even if you don't feel up to writing code or documentation yet, there are a variety of other ways that you can contribute, from reporting issues to testing patches.
 
+As mentioned in [Rails
+README](https://github.com/rails/rails/blob/master/README.md), everyone interacting in Rails and its sub-projects' codebases, issue trackers, chat rooms, and mailing lists is expected to follow the Rails [code of conduct](https://github.com/rails/rails/blob/master/CODE_OF_CONDUCT.md).
+
 --------------------------------------------------------------------------------
 
 Reporting an Issue
@@ -28,19 +31,23 @@ NOTE: Bugs in the most recent released version of Ruby on Rails are likely to ge
 
 If you've found a problem in Ruby on Rails which is not a security risk, do a search on GitHub under [Issues](https://github.com/rails/rails/issues) in case it has already been reported. If you are unable to find any open GitHub issues addressing the problem you found, your next step will be to [open a new one](https://github.com/rails/rails/issues/new). (See the next section for reporting security issues.)
 
-Your issue report should contain a title and a clear description of the issue at the bare minimum. You should include as much relevant information as possible and should at least post a code sample that demonstrates the issue. It would be even better if you could include a unit test that shows how the expected behavior is not occurring. Your goal should be to make it easy for yourself - and others - to replicate the bug and figure out a fix.
+Your issue report should contain a title and a clear description of the issue at the bare minimum. You should include as much relevant information as possible and should at least post a code sample that demonstrates the issue. It would be even better if you could include a unit test that shows how the expected behavior is not occurring. Your goal should be to make it easy for yourself - and others - to reproduce the bug and figure out a fix.
 
 Then, don't get your hopes up! Unless you have a "Code Red, Mission Critical, the World is Coming to an End" kind of bug, you're creating this issue report in the hope that others with the same problem will be able to collaborate with you on solving it. Do not expect that the issue report will automatically see any activity or that others will jump to fix it. Creating an issue like this is mostly to help yourself start on the path of fixing the problem and for others to confirm it with an "I'm having this problem too" comment.
 
-### Create a Self-Contained gist for Active Record and Action Controller Issues
+### Create an Executable Test Case
+
+Having a way to reproduce your issue will be very helpful for others to help confirm, investigate and ultimately fix your issue. You can do this by providing an executable test case. To make this process easier, we have prepared several bug report templates for you to use as a starting point:
+
+* Template for Active Record (models, database) issues: [gem](https://github.com/rails/rails/blob/master/guides/bug_report_templates/active_record_gem.rb) / [master](https://github.com/rails/rails/blob/master/guides/bug_report_templates/active_record_master.rb)
+* Template for Action Pack (controllers, routing) issues: [gem](https://github.com/rails/rails/blob/master/guides/bug_report_templates/action_controller_gem.rb) / [master](https://github.com/rails/rails/blob/master/guides/bug_report_templates/action_controller_master.rb)
+* Generic template for other issues: [gem](https://github.com/rails/rails/blob/master/guides/bug_report_templates/generic_gem.rb) / [master](https://github.com/rails/rails/blob/master/guides/bug_report_templates/generic_master.rb)
+
+These templates include the boilerplate code to set up a test case against either a released version of Rails (`*_gem.rb`) or edge Rails (`*_master.rb`).
 
-If you are filing a bug report, please use
-[Active Record template for gems](https://github.com/rails/rails/blob/master/guides/bug_report_templates/active_record_gem.rb) or
-[Action Controller template for gems](https://github.com/rails/rails/blob/master/guides/bug_report_templates/action_controller_gem.rb)
-if the bug is found in a published gem, and
-[Active Record template for master](https://github.com/rails/rails/blob/master/guides/bug_report_templates/active_record_master.rb) or
-[Action Controller template for master](https://github.com/rails/rails/blob/master/guides/bug_report_templates/action_controller_master.rb)
-if the bug happens in the master branch.
+Simply copy the content of the appropriate template into a `.rb` file and make the necessary changes to demonstrate the issue. You can execute it by running `ruby the_file.rb` in your terminal. If all goes well, you should see your test case failing.
+
+You can then share your executable test case as a [gist](https://gist.github.com), or simply paste the content into the issue description.
 
 ### Special Treatment for Security Issues
 
@@ -57,12 +64,12 @@ can expect it to be marked "invalid" as soon as it's reviewed.
 
 Sometimes, the line between 'bug' and 'feature' is a hard one to draw.
 Generally, a feature is anything that adds new behavior, while a bug is
-anything that fixes already existing behavior that is misbehaving. Sometimes,
+anything that causes incorrect behavior. Sometimes,
 the core team will have to make a judgement call. That said, the distinction
 generally just affects which release your patch will get in to; we love feature
 submissions! They just won't get backported to maintenance branches.
 
-If you'd like feedback on an idea for a feature before doing the work for make
+If you'd like feedback on an idea for a feature before doing the work to make
 a patch, please send an email to the [rails-core mailing
 list](https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-core). You
 might get no response, which means that everyone is indifferent. You might find
@@ -75,17 +82,17 @@ discussions new features require.
 Helping to Resolve Existing Issues
 ----------------------------------
 
-As a next step beyond reporting issues, you can help the core team resolve existing issues. If you check the [Everyone's Issues](https://github.com/rails/rails/issues) list in GitHub Issues, you'll find lots of issues already requiring attention. What can you do for these? Quite a bit, actually:
+As a next step beyond reporting issues, you can help the core team resolve existing issues. If you check the [issues list](https://github.com/rails/rails/issues) in GitHub Issues, you'll find lots of issues already requiring attention. What can you do for these? Quite a bit, actually:
 
 ### Verifying Bug Reports
 
 For starters, it helps just to verify bug reports. Can you reproduce the reported issue on your own computer? If so, you can add a comment to the issue saying that you're seeing the same thing.
 
-If something is very vague, can you help squash it down into something specific? Maybe you can provide additional information to help reproduce a bug, or help by eliminating needless steps that aren't required to demonstrate the problem.
+If an issue is very vague, can you help narrow it down to something more specific? Maybe you can provide additional information to help reproduce a bug, or help by eliminating needless steps that aren't required to demonstrate the problem.
 
 If you find a bug report without a test, it's very useful to contribute a failing test. This is also a great way to get started exploring the source code: looking at the existing test files will teach you how to write more tests. New tests are best contributed in the form of a patch, as explained later on in the "Contributing to the Rails Code" section.
 
-Anything you can do to make bug reports more succinct or easier to reproduce is a help to folks trying to write code to fix those bugs - whether you end up writing the code yourself or not.
+Anything you can do to make bug reports more succinct or easier to reproduce helps folks trying to write code to fix those bugs - whether you end up writing the code yourself or not.
 
 ### Testing Patches
 
@@ -113,7 +120,7 @@ Once you're happy that the pull request contains a good change, comment on the G
 
 >I like the way you've restructured that code in generate_finder_sql - much nicer. The tests look good too.
 
-If your comment simply says "+1", then odds are that other reviewers aren't going to take it too seriously. Show that you took the time to review the pull request.
+If your comment simply reads "+1", then odds are that other reviewers aren't going to take it too seriously. Show that you took the time to review the pull request.
 
 Contributing to the Rails Documentation
 ---------------------------------------
@@ -121,7 +128,7 @@ Contributing to the Rails Documentation
 Ruby on Rails has two main sets of documentation: the guides, which help you
 learn about Ruby on Rails, and the API, which serves as a reference.
 
-You can help improve the Rails guides by making them more coherent, consistent or readable, adding missing information, correcting factual errors, fixing typos, or bringing it up to date with the latest edge Rails. To get involved in the translation of Rails guides, please see [Translating Rails Guides](https://wiki.github.com/rails/docrails/translating-rails-guides).
+You can help improve the Rails guides by making them more coherent, consistent or readable, adding missing information, correcting factual errors, fixing typos, or bringing them up to date with the latest edge Rails. To get involved in the translation of Rails guides, please see [Translating Rails Guides](https://wiki.github.com/rails/docrails/translating-rails-guides).
 
 You can either open a pull request to [Rails](http://github.com/rails/rails) or
 ask the [Rails core team](http://rubyonrails.org/core) for commit access on
@@ -173,6 +180,14 @@ $ git checkout -b my_new_branch
 
 It doesn't matter much what name you use, because this branch will only exist on your local computer and your personal repository on GitHub. It won't be part of the Rails Git repository.
 
+### Bundle install
+
+Install the required gems.
+
+```bash
+$ bundle install
+```
+
 ### Running an Application Against Your Local Branch
 
 In case you need a dummy Rails app to test changes, the `--dev` flag of `rails new` generates an application that uses your local branch:
@@ -236,11 +251,11 @@ This will generate a report with the following information:
 
 ```
 Calculating -------------------------------------
-            addition     69114 i/100ms
-  addition with send     64062 i/100ms
+            addition   132.013k i/100ms
+  addition with send   125.413k i/100ms
 -------------------------------------------------
-            addition  5307644.4 (±3.5%) i/s -   26539776 in   5.007219s
-  addition with send  3702897.9 (±3.5%) i/s -   18513918 in   5.006723s
+            addition      9.677M (± 1.7%) i/s -     48.449M
+  addition with send      6.794M (± 1.1%) i/s -     33.987M
 ```
 
 Please see the benchmark/ips [README](https://github.com/evanphx/benchmark-ips/blob/master/README.md) for more information.
@@ -283,7 +298,7 @@ You can run a single test through ruby. For instance:
 
 ```bash
 $ cd actionmailer
-$ ruby -w -Itest test/mail_layout_test.rb -n test_explicit_class_layout
+$ bundle exec ruby -w -Itest test/mail_layout_test.rb -n test_explicit_class_layout
 ```
 
 The `-n` option allows you to run a single method instead of the whole
@@ -303,7 +318,7 @@ $ cd activerecord
 $ bundle exec rake test:sqlite3
 ```
 
-You can now run the tests as you did for `sqlite3`. The tasks are respectively
+You can now run the tests as you did for `sqlite3`. The tasks are respectively:
 
 ```bash
 test:mysql
@@ -322,7 +337,7 @@ will now run the four of them in turn.
 You can also run any single test separately:
 
 ```bash
-$ ARCONN=sqlite3 ruby -Itest test/cases/associations/has_many_associations_test.rb
+$ ARCONN=sqlite3 bundle exec ruby -Itest test/cases/associations/has_many_associations_test.rb
 ```
 
 To run a single test against all adapters, use:
@@ -347,9 +362,9 @@ $ RUBYOPT=-W0 bundle exec rake test
 
 The CHANGELOG is an important part of every release. It keeps the list of changes for every Rails version.
 
-You should add an entry to the CHANGELOG of the framework that you modified if you're adding or removing a feature, committing a bug fix or adding deprecation notices. Refactorings and documentation changes generally should not go to the CHANGELOG.
+You should add an entry **to the top** of the CHANGELOG of the framework that you modified if you're adding or removing a feature, committing a bug fix or adding deprecation notices. Refactorings and documentation changes generally should not go to the CHANGELOG.
 
-A CHANGELOG entry should summarize what was changed and should end with author's name and it should go on top of a CHANGELOG. You can use multiple lines if you need more space and you can attach code examples indented with 4 spaces. If a change is related to a specific issue, you should attach the issue's number. Here is an example CHANGELOG entry:
+A CHANGELOG entry should summarize what was changed and should end with the author's name. You can use multiple lines if you need more space and you can attach code examples indented with 4 spaces. If a change is related to a specific issue, you should attach the issue's number. Here is an example CHANGELOG entry:
 
 ```
 *   Summary of a change that briefly describes what was changed. You can use multiple
@@ -366,7 +381,12 @@ A CHANGELOG entry should summarize what was changed and should end with author's
     *Your Name*
 ```
 
-Your name can be added directly after the last word if you don't provide any code examples or don't need multiple paragraphs. Otherwise, it's best to make as a new paragraph.
+Your name can be added directly after the last word if there are no code
+examples or multiple paragraphs. Otherwise, it's best to make a new paragraph.
+
+### Updating the Gemfile.lock
+
+Some changes require the dependencies to be upgraded. In these cases make sure you run `bundle update` to get the right version of the dependency and commit the `Gemfile.lock` file within your changes.
 
 ### Sanity Check
 
@@ -386,21 +406,27 @@ When you're happy with the code on your computer, you need to commit the changes
 $ git commit -a
 ```
 
-At this point, your editor should be fired up and you can write a message for this commit. Well formatted and descriptive commit messages are extremely helpful for the others, especially when figuring out why given change was made, so please take the time to write it.
+This should fire up your editor to write a commit message. When you have
+finished, save and close to continue.
+
+A well-formatted and descriptive commit message is very helpful to others for
+understanding why the change was made, so please take the time to write it.
 
-Good commit message should be formatted according to the following example:
+A good commit message looks like this:
 
 ```
 Short summary (ideally 50 characters or less)
 
-More detailed description, if necessary. It should be wrapped to 72
-characters. Try to be as descriptive as you can, even if you think that
-the commit content is obvious, it may not be obvious to others. You
-should add such description also if it's already present in bug tracker,
-it should not be necessary to visit a webpage to check the history.
+More detailed description, if necessary. It should be wrapped to
+72 characters. Try to be as descriptive as you can. Even if you
+think that the commit content is obvious, it may not be obvious
+to others. Add any description that is already present in the
+relevant issues; it should not be necessary to visit a webpage
+to check the history.
+
+The description section can have multiple paragraphs.
 
-Description can have multiple paragraphs and you can use code examples
-inside, just indent it with 4 spaces:
+Code examples can be embedded by indenting them with 4 spaces:
 
     class ArticlesController
       def index
@@ -410,13 +436,15 @@ inside, just indent it with 4 spaces:
 
 You can also add bullet points:
 
-- you can use dashes or asterisks
+- make a bullet point by starting a line with either a dash (-)
+  or an asterisk (*)
 
-- also, try to indent next line of a point for readability, if it's too
-  long to fit in 72 characters
+- wrap lines at 72 characters, and indent any additional lines
+  with 2 spaces for readability
 ```
 
-TIP. Please squash your commits into a single commit when appropriate. This simplifies future cherry picks, and also keeps the git log clean.
+TIP. Please squash your commits into a single commit when appropriate. This
+simplifies future cherry picks and keeps the git log clean.
 
 ### Update Your Branch
 
@@ -507,7 +535,7 @@ pull request". The Rails core team will be notified about your submission.
 
 Most pull requests will go through a few iterations before they get merged.
 Different contributors will sometimes have different opinions, and often
-patches will need revised before they can get merged.
+patches will need to be revised before they can get merged.
 
 Some contributors to Rails have email notifications from GitHub turned on, but
 others do not. Furthermore, (almost) everyone who works on Rails is a
@@ -554,8 +582,7 @@ following:
 ```bash
 $ git fetch upstream
 $ git checkout my_pull_request
-$ git rebase upstream/master
-$ git rebase -i
+$ git rebase -i upstream/master
 
 < Choose 'squash' for all of your commits except the first one. >
 < Edit the commit message to make sense, and describe all your changes. >
diff --git a/guides/source/credits.html.erb b/guides/source/credits.html.erb
index 61ea0b44ef..1d995581fa 100644
--- a/guides/source/credits.html.erb
+++ b/guides/source/credits.html.erb
@@ -28,7 +28,7 @@ Ruby on Rails Guides: Credits
 <h3 class="section">Rails Guides Authors</h3>
 
 <%= author('Ryan Bigg', 'radar', 'radar.png') do %>
-  Ryan Bigg works as the Community Manager at <a href="http://spreecommerce.com">Spree Commerce</a> and has been working with Rails since 2006. He's the author of <a href="https://leanpub.com/multi-tenancy-rails">Multi Tenancy With Rails</a> and co-author of <a href="http://manning.com/bigg2">Rails 4 in Action</a>. He's written many gems which can be seen on <a href="https://github.com/radar">his GitHub page</a> and he also tweets prolifically as <a href="http://twitter.com/ryanbigg">@ryanbigg</a>.
+  Ryan Bigg works as a Rails developer at <a href="http://marketplacer.com">Marketplacer</a> and has been working with Rails since 2006. He's the author of <a href="https://leanpub.com/multi-tenancy-rails">Multi Tenancy With Rails</a> and co-author of <a href="http://manning.com/bigg2">Rails 4 in Action</a>. He's written many gems which can be seen on <a href="https://github.com/radar">his GitHub page</a> and he also tweets prolifically as <a href="http://twitter.com/ryanbigg">@ryanbigg</a>.
 <% end %>
 
 <%= author('Oscar Del Ben', 'oscardelben', 'oscardelben.jpg') do %>
diff --git a/guides/source/debugging_rails_applications.md b/guides/source/debugging_rails_applications.md
index a788dd48ad..a05abb61d6 100644
--- a/guides/source/debugging_rails_applications.md
+++ b/guides/source/debugging_rails_applications.md
@@ -17,7 +17,7 @@ After reading this guide, you will know:
 View Helpers for Debugging
 --------------------------
 
-One common task is to inspect the contents of a variable. In Rails, you can do this with three methods:
+One common task is to inspect the contents of a variable. Rails provides three different ways to do this:
 
 * `debug`
 * `to_yaml`
@@ -54,7 +54,7 @@ Title: Rails debugging guide
 
 ### `to_yaml`
 
-Displaying an instance variable, or any other object or method, in YAML format can be achieved this way:
+Alternatively, calling `to_yaml` on any object converts it to YAML. You can pass this converted object into the `simple_format` helper method to format the output. This is how `debug` does its magic.
 
 ```html+erb
 <%= simple_format @article.to_yaml %>
@@ -64,9 +64,7 @@ Displaying an instance variable, or any other object or method, in YAML format c
 </p>
 ```
 
-The `to_yaml` method converts the method to YAML format leaving it more readable, and then the `simple_format` helper is used to render each line as in the console. This is how `debug` method does its magic.
-
-As a result of this, you will have something like this in your view:
+The above code will render something like this:
 
 ```yaml
 --- !ruby/object Article
@@ -94,7 +92,7 @@ Another useful method for displaying object values is `inspect`, especially when
 </p>
 ```
 
-Will be rendered as follows:
+Will render:
 
 ```
 [1, 2, 3, 4, 5]
@@ -109,9 +107,9 @@ It can also be useful to save information to log files at runtime. Rails maintai
 
 ### What is the Logger?
 
-Rails makes use of the `ActiveSupport::Logger` class to write log information. You can also substitute another logger such as `Log4r` if you wish.
+Rails makes use of the `ActiveSupport::Logger` class to write log information. Other loggers, such as `Log4r`, may also be substituted.
 
-You can specify an alternative logger in your `environment.rb` or any environment file:
+You can specify an alternative logger in `environment.rb` or any other environment file, for example:
 
 ```ruby
 Rails.logger = Logger.new(STDOUT)
@@ -129,16 +127,21 @@ TIP: By default, each log is created under `Rails.root/log/` and the log file is
 
 ### Log Levels
 
-When something is logged it's printed into the corresponding log if the log level of the message is equal or higher than the configured log level. If you want to know the current log level you can call the `Rails.logger.level` method.
+When something is logged, it's printed into the corresponding log if the log
+level of the message is equal to or higher than the configured log level. If you
+want to know the current log level, you can call the `Rails.logger.level`
+method.
 
-The available log levels are: `:debug`, `:info`, `:warn`, `:error`, `:fatal`, and `:unknown`, corresponding to the log level numbers from 0 up to 5 respectively. To change the default log level, use
+The available log levels are: `:debug`, `:info`, `:warn`, `:error`, `:fatal`,
+and `:unknown`, corresponding to the log level numbers from 0 up to 5,
+respectively. To change the default log level, use
 
 ```ruby
 config.log_level = :warn # In any environment initializer, or
 Rails.logger.level = 0 # at any time
 ```
 
-This is useful when you want to log under development or staging, but you don't want to flood your production log with unnecessary information.
+This is useful when you want to log under development or staging without flooding your production log with unnecessary information.
 
 TIP: The default Rails log level is `debug` in all environments.
 
@@ -202,7 +205,7 @@ Adding extra logging like this makes it easy to search for unexpected or unusual
 
 When running multi-user, multi-account applications, it's often useful
 to be able to filter the logs using some custom rules. `TaggedLogging`
-in Active Support helps in doing exactly that by stamping log lines with subdomains, request ids, and anything else to aid debugging such applications.
+in Active Support helps you do exactly that by stamping log lines with subdomains, request ids, and anything else to aid debugging such applications.
 
 ```ruby
 logger = ActiveSupport::TaggedLogging.new(Logger.new(STDOUT))
@@ -212,34 +215,33 @@ logger.tagged("BCX") { logger.tagged("Jason") { logger.info "Stuff" } } # Logs "
 ```
 
 ### Impact of Logs on Performance
-Logging will always have a small impact on performance of your rails app,
-        particularly when logging to disk. However, there are a few subtleties:
+Logging will always have a small impact on the performance of your Rails app,
+        particularly when logging to disk. Additionally, there are a few subtleties:
 
 Using the `:debug` level will have a greater performance penalty than `:fatal`,
       as a far greater number of strings are being evaluated and written to the
       log output (e.g. disk).
 
-Another potential pitfall is that if you have many calls to `Logger` like this
-      in your code:
+Another potential pitfall is too many calls to `Logger` in your code:
 
 ```ruby
 logger.debug "Person attributes hash: #{@person.attributes.inspect}"
 ```
 
-In the above example, There will be a performance impact even if the allowed
+In the above example, there will be a performance impact even if the allowed
 output level doesn't include debug. The reason is that Ruby has to evaluate
 these strings, which includes instantiating the somewhat heavy `String` object
-and interpolating the variables, and which takes time.
+and interpolating the variables.
 Therefore, it's recommended to pass blocks to the logger methods, as these are
-only evaluated if the output level is the same or included in the allowed level
+only evaluated if the output level is the same as — or included in — the allowed level
 (i.e. lazy loading). The same code rewritten would be:
 
 ```ruby
 logger.debug {"Person attributes hash: #{@person.attributes.inspect}"}
 ```
 
-The contents of the block, and therefore the string interpolation, is only
-evaluated if debug is enabled. This performance savings is only really
+The contents of the block, and therefore the string interpolation, are only
+evaluated if debug is enabled. This performance savings are only really
 noticeable with large amounts of logging, but it's a good practice to employ.
 
 Debugging with the `byebug` gem
@@ -253,8 +255,7 @@ is your best companion.
 
 The debugger can also help you if you want to learn about the Rails source code
 but don't know where to start. Just debug any request to your application and
-use this guide to learn how to move from the code you have written deeper into
-Rails code.
+use this guide to learn how to move from the code you have written into the underlying Rails code.
 
 ### Setup
 
@@ -285,7 +286,7 @@ As soon as your application calls the `byebug` method, the debugger will be
 started in a debugger shell inside the terminal window where you launched your
 application server, and you will be placed at the debugger's prompt `(byebug)`.
 Before the prompt, the code around the line that is about to be run will be
-displayed and the current line will be marked by '=>'. Like this:
+displayed and the current line will be marked by '=>', like this:
 
 ```
 [1, 10] in /PathTo/project/app/controllers/articles_controller.rb
@@ -316,7 +317,7 @@ For example:
 => Notice: server is listening on all interfaces (0.0.0.0). Consider using 127.0.0.1 (--binding option)
 => Ctrl-C to shutdown server
 [2014-04-11 13:11:47] INFO  WEBrick 1.3.1
-[2014-04-11 13:11:47] INFO  ruby 2.1.1 (2014-02-24) [i686-linux]
+[2014-04-11 13:11:47] INFO  ruby 2.2.2 (2015-04-13) [i686-linux]
 [2014-04-11 13:11:47] INFO  WEBrick::HTTPServer#start: pid=6370 port=3000
 
 
@@ -339,30 +340,20 @@ Processing by ArticlesController#index as HTML
 (byebug)
 ```
 
-Now it's time to explore and dig into your application. A good place to start is
+Now it's time to explore your application. A good place to start is
 by asking the debugger for help. Type: `help`
 
 ```
 (byebug) help
 
-byebug 2.7.0
-
-Type 'help <command-name>' for help on a specific command
+  h[elp][ <cmd>[ <subcmd>]]
 
-Available commands:
-backtrace  delete   enable  help       list    pry next  restart  source     up
-break      disable  eval    info       method  ps        save     step       var
-catch      display  exit    interrupt  next    putl      set      thread
-condition  down     finish  irb        p       quit      show     trace
-continue   edit     frame   kill       pp      reload    skip     undisplay
+  help                -- prints this help.
+  help <cmd>          -- prints help on command <cmd>.
+  help <cmd> <subcmd> -- prints help on <cmd>'s subcommand <subcmd>.
 ```
 
-TIP: To view the help menu for any command use `help <command-name>` at the
-debugger prompt. For example: _`help list`_. You can abbreviate any debugging
-command by supplying just enough letters to distinguish them from other
-commands, so you can also use `l` for the `list` command, for example.
-
-To see the previous ten lines you should type `list-` (or `l-`)
+To see the previous ten lines you should type `list-` (or `l-`).
 
 ```
 (byebug) l-
@@ -381,7 +372,7 @@ To see the previous ten lines you should type `list-` (or `l-`)
 
 ```
 
-This way you can move inside the file, being able to see the code above and over
+This way you can move inside the file and see the code above
 the line where you added the `byebug` call. Finally, to see where you are in
 the code again you can type `list=`
 
@@ -411,8 +402,7 @@ contexts as you go through the different parts of the stack.
 The debugger creates a context when a stopping point or an event is reached. The
 context has information about the suspended program which enables the debugger
 to inspect the frame stack, evaluate variables from the perspective of the
-debugged program, and contains information about the place where the debugged
-program is stopped.
+debugged program, and know the place where the debugged program is stopped.
 
 At any time you can call the `backtrace` command (or its alias `where`) to print
 the backtrace of the application. This can be very helpful to know how you got
@@ -469,16 +459,15 @@ The debugger can list, stop, resume and switch between running threads by using
 the `thread` command (or the abbreviated `th`). This command has a handful of
 options:
 
-* `thread` shows the current thread.
-* `thread list` is used to list all threads and their statuses. The plus +
+* `thread`: shows the current thread.
+* `thread list`: is used to list all threads and their statuses. The plus +
 character and the number indicates the current thread of execution.
-* `thread stop _n_` stop thread _n_.
-* `thread resume _n_` resumes thread _n_.
-* `thread switch _n_` switches the current thread context to _n_.
+* `thread stop _n_`: stop thread _n_.
+* `thread resume _n_`: resumes thread _n_.
+* `thread switch _n_`: switches the current thread context to _n_.
 
-This command is very helpful, among other occasions, when you are debugging
-concurrent threads and need to verify that there are no race conditions in your
-code.
+This command is very helpful when you are debugging concurrent threads and need
+to verify that there are no race conditions in your code.
 
 ### Inspecting Variables
 
@@ -503,7 +492,7 @@ current context:
 
 (byebug) instance_variables
 [:@_action_has_layout, :@_routes, :@_headers, :@_status, :@_request,
- :@_response, :@_env, :@_prefixes, :@_lookup_context, :@_action_name,
+ :@_response, :@_prefixes, :@_lookup_context, :@_action_name,
  :@_response_body, :@marked_for_same_origin_verification, :@_config]
 ```
 
@@ -532,19 +521,22 @@ command later in this guide).
 And then ask again for the instance_variables:
 
 ```
-(byebug) instance_variables.include? "@articles"
-true
+(byebug) instance_variables
+[:@_action_has_layout, :@_routes, :@_headers, :@_status, :@_request,
+ :@_response, :@_prefixes, :@_lookup_context, :@_action_name,
+ :@_response_body, :@marked_for_same_origin_verification, :@_config,
+ :@articles]
 ```
 
 Now `@articles` is included in the instance variables, because the line defining it
 was executed.
 
 TIP: You can also step into **irb** mode with the command `irb` (of course!).
-This way an irb session will be started within the context you invoked it. But
+This will start an irb session within the context you invoked it. But
 be warned: this is an experimental feature.
 
 The `var` method is the most convenient way to show variables and their values.
-Let's let `byebug` to help us with it.
+Let's have `byebug` help us with it.
 
 ```
 (byebug) help var
@@ -556,7 +548,7 @@ v[ar] l[ocal]                   show local variables
 ```
 
 This is a great way to inspect the values of the current context variables. For
-example, to check that we have no local variables currently defined.
+example, to check that we have no local variables currently defined:
 
 ```
 (byebug) var local
@@ -587,14 +579,14 @@ tracking the values of a variable while the execution goes on.
 1: @articles = nil
 ```
 
-The variables inside the displaying list will be printed with their values after
+The variables inside the displayed list will be printed with their values after
 you move in the stack. To stop displaying a variable use `undisplay _n_` where
 _n_ is the variable number (1 in the last example).
 
 ### Step by Step
 
 Now you should know where you are in the running trace and be able to print the
-available variables. But lets continue and move on with the application
+available variables. But let's continue and move on with the application
 execution.
 
 Use `step` (abbreviated `s`) to continue running your program until the next
@@ -628,13 +620,16 @@ Processing by ArticlesController#index as HTML
 (byebug)
 ```
 
-If we use `next`, we want go deep inside method calls. Instead, byebug will go
-to the next line within the same context. In this case, this is the last line of
-the method, so `byebug` will jump to next next line of the previous frame.
+If we use `next`, we won't go deep inside method calls. Instead, `byebug` will
+go to the next line within the same context. In this case, it is the last line
+of the current method, so `byebug` will return to the next line of the caller
+method.
 
 ```
 (byebug) next
-Next went up a frame because previous frame finished
+
+Next advances to the next line (line 6: `end`), which returns to the next line
+of the caller method:
 
 [4, 13] in /PathTo/project/test_app/app/controllers/articles_controller.rb
     4:   # GET /articles
@@ -651,8 +646,8 @@ Next went up a frame because previous frame finished
 (byebug)
 ```
 
-If we use `step` in the same situation, we will literally go the next ruby
-instruction to be executed. In this case, the activesupport's `week` method.
+If we use `step` in the same situation, `byebug` will literally go to the next
+Ruby instruction to be executed -- in this case, Active Support's `week` method.
 
 ```
 (byebug) step
@@ -672,8 +667,7 @@ instruction to be executed. In this case, the activesupport's `week` method.
 (byebug)
 ```
 
-This is one of the best ways to find bugs in your code, or perhaps in Ruby on
-Rails.
+This is one of the best ways to find bugs in your code.
 
 ### Breakpoints
 
@@ -751,12 +745,12 @@ To list all active catchpoints use `catch`.
 There are two ways to resume execution of an application that is stopped in the
 debugger:
 
-* `continue` [line-specification] \(or `c`): resume program execution, at the
+* `continue [line-specification]` \(or `c`): resume program execution, at the
 address where your script last stopped; any breakpoints set at that address are
 bypassed. The optional argument line-specification allows you to specify a line
 number to set a one-time breakpoint which is deleted when that breakpoint is
 reached.
-* `finish` [frame-number] \(or `fin`): execute until the selected stack frame
+* `finish [frame-number]` \(or `fin`): execute until the selected stack frame
 returns. If no frame number is given, the application will run until the
 currently selected frame returns. The currently selected frame starts out the
 most-recent frame or 0 if no frame positioning (e.g up, down or frame) has been
@@ -772,20 +766,20 @@ environment variable. A specific _line_ can also be given.
 
 ### Quitting
 
-To exit the debugger, use the `quit` command (abbreviated `q`), or its alias
-`exit`.
+To exit the debugger, use the `quit` command (abbreviated to `q`). Or, type `q!`
+to bypass the `Really quit? (y/n)` prompt and exit unconditionally.
 
 A simple quit tries to terminate all threads in effect. Therefore your server
 will be stopped and you will have to start it again.
 
 ### Settings
 
-`byebug` has a few available options to tweak its behaviour:
+`byebug` has a few available options to tweak its behavior:
 
-* `set autoreload`: Reload source code when changed (default: true).
-* `set autolist`: Execute `list` command on every breakpoint (default: true).
+* `set autoreload`: Reload source code when changed (defaults: true).
+* `set autolist`: Execute `list` command on every breakpoint (defaults: true).
 * `set listsize _n_`: Set number of source lines to list by default to _n_
-(default: 10)
+(defaults: 10)
 * `set forcestep`: Make sure the `next` and `step` commands always move to a new
 line.
 
@@ -800,10 +794,67 @@ set forcestep
 set listsize 25
 ```
 
+Debugging with the `web-console` gem
+------------------------------------
+
+Web Console is a bit like `byebug`, but it runs in the browser. In any page you
+are developing, you can request a console in the context of a view or a
+controller. The console would be rendered next to your HTML content.
+
+### Console
+
+Inside any controller action or view, you can invoke the console by
+calling the `console` method.
+
+For example, in a controller:
+
+```ruby
+class PostsController < ApplicationController
+  def new
+    console
+    @post = Post.new
+  end
+end
+```
+
+Or in a view:
+
+```html+erb
+<% console %>
+
+<h2>New Post</h2>
+```
+
+This will render a console inside your view. You don't need to care about the
+location of the `console` call; it won't be rendered on the spot of its
+invocation but next to your HTML content.
+
+The console executes pure Ruby code: You can define and instantiate
+custom classes, create new models and inspect variables.
+
+NOTE: Only one console can be rendered per request. Otherwise `web-console`
+will raise an error on the second `console` invocation.
+
+### Inspecting Variables
+
+You can invoke `instance_variables` to list all the instance variables
+available in your context. If you want to list all the local variables, you can
+do that with `local_variables`.
+
+### Settings
+
+* `config.web_console.whitelisted_ips`: Authorized list of IPv4 or IPv6
+addresses and networks (defaults: `127.0.0.1/8, ::1`).
+* `config.web_console.whiny_requests`: Log a message when a console rendering
+is prevented (defaults: `true`).
+
+Since `web-console` evaluates plain Ruby code remotely on the server, don't try
+to use it in production.
+
 Debugging Memory Leaks
 ----------------------
 
-A Ruby application (on Rails or not), can leak memory - either in the Ruby code
+A Ruby application (on Rails or not), can leak memory — either in the Ruby code
 or at the C code level.
 
 In this section, you will learn how to find and fix such leaks by using tool
@@ -832,9 +883,9 @@ application. Here is a list of useful plugins for debugging:
 * [Footnotes](https://github.com/josevalim/rails-footnotes) Every Rails page has
 footnotes that give request information and link back to your source via
 TextMate.
-* [Query Trace](https://github.com/ntalbott/query_trace/tree/master) Adds query
+* [Query Trace](https://github.com/ruckus/active-record-query-trace/tree/master) Adds query
 origin tracing to your logs.
-* [Query Reviewer](https://github.com/nesquena/query_reviewer) This rails plugin
+* [Query Reviewer](https://github.com/nesquena/query_reviewer) This Rails plugin
 not only runs "EXPLAIN" before each of your select queries in development, but
 provides a small DIV in the rendered output of each page with the summary of
 warnings for each query that it analyzed.
@@ -846,7 +897,7 @@ standard Rails error page with a new one containing more contextual information,
 like source code and variable inspection.
 * [RailsPanel](https://github.com/dejan/rails_panel) Chrome extension for Rails
 development that will end your tailing of development.log. Have all information
-about your Rails app requests in the browser - in the Developer Tools panel.
+about your Rails app requests in the browser — in the Developer Tools panel.
 Provides insight to db/rendering/total times, parameter list, rendered views and
 more.
 
@@ -856,6 +907,7 @@ References
 * [ruby-debug Homepage](http://bashdb.sourceforge.net/ruby-debug/home-page.html)
 * [debugger Homepage](https://github.com/cldwalker/debugger)
 * [byebug Homepage](https://github.com/deivid-rodriguez/byebug)
+* [web-console Homepage](https://github.com/rails/web-console)
 * [Article: Debugging a Rails application with ruby-debug](http://www.sitepoint.com/debug-rails-app-ruby-debug/)
 * [Ryan Bates' debugging ruby (revised) screencast](http://railscasts.com/episodes/54-debugging-ruby-revised)
 * [Ryan Bates' stack trace screencast](http://railscasts.com/episodes/24-the-stack-trace)
diff --git a/guides/source/development_dependencies_install.md b/guides/source/development_dependencies_install.md
index 989b29956c..4322f03d05 100644
--- a/guides/source/development_dependencies_install.md
+++ b/guides/source/development_dependencies_install.md
@@ -9,7 +9,7 @@ After reading this guide, you will know:
 
 * How to set up your machine for Rails development
 * How to run specific groups of unit tests from the Rails test suite
-* How the ActiveRecord portion of the Rails test suite operates
+* How the Active Record portion of the Rails test suite operates
 
 --------------------------------------------------------------------------------
 
@@ -21,14 +21,14 @@ The easiest and recommended way to get a development environment ready to hack i
 The Hard Way
 ------------
 
-In case you can't use the Rails development box, see section above, these are the steps to manually build a development box for Ruby on Rails core development.
+In case you can't use the Rails development box, see section below, these are the steps to manually build a development box for Ruby on Rails core development.
 
 ### Install Git
 
 Ruby on Rails uses Git for source code control. The [Git homepage](http://git-scm.com/) has installation instructions. There are a variety of resources on the net that will help you get familiar with Git:
 
 * [Try Git course](http://try.github.io/) is an interactive course that will teach you the basics.
-* The [official Documentation](http://git-scm.com/documentation) is pretty comprehensive and also contains some videos with the basics of Git
+* The [official Documentation](http://git-scm.com/documentation) is pretty comprehensive and also contains some videos with the basics of Git.
 * [Everyday Git](http://schacon.github.io/git/everyday.html) will teach you just enough about Git to get by.
 * The [PeepCode screencast](https://peepcode.com/products/git) on Git is easier to follow.
 * [GitHub](http://help.github.com) offers links to a variety of Git resources.
@@ -60,7 +60,7 @@ In Ubuntu you're done with just:
 $ sudo apt-get install sqlite3 libsqlite3-dev
 ```
 
-And if you are on Fedora or CentOS, you're done with
+If you are on Fedora or CentOS, you're done with
 
 ```bash
 $ sudo yum install sqlite3 sqlite3-devel
@@ -190,7 +190,7 @@ Follow the instructions given by Homebrew to start these.
 In Ubuntu just run:
 
 ```bash
-$ sudo apt-get install mysql-server libmysqlclient15-dev
+$ sudo apt-get install mysql-server libmysqlclient-dev
 $ sudo apt-get install postgresql postgresql-client postgresql-contrib libpq-dev
 ```
 
@@ -213,7 +213,7 @@ FreeBSD users will have to run the following:
 
 ```bash
 # pkg install mysql56-client mysql56-server
-# pkg install postgresql93-client postgresql93-server
+# pkg install postgresql94-client postgresql94-server
 ```
 
 Or install them through ports (they are located under the `databases` folder).
diff --git a/guides/source/documents.yaml b/guides/source/documents.yaml
index 67032a31f5..4473eba478 100644
--- a/guides/source/documents.yaml
+++ b/guides/source/documents.yaml
@@ -11,7 +11,7 @@
     -
       name: Active Record Basics
       url: active_record_basics.html
-      description: This guide will get you started with models, persistence to database and the Active Record pattern and library.
+      description: This guide will get you started with models, persistence to database, and the Active Record pattern and library.
     -
       name: Active Record Migrations
       url: active_record_migrations.html
@@ -19,7 +19,7 @@
     -
       name: Active Record Validations
       url: active_record_validations.html
-      description: This guide covers how you can use Active Record validations
+      description: This guide covers how you can use Active Record validations.
     -
       name: Active Record Callbacks
       url: active_record_callbacks.html
@@ -33,7 +33,7 @@
       url: active_record_querying.html
       description: This guide covers the database query interface provided by Active Record.
     -
-      name: Active Model basics
+      name: Active Model Basics
       url: active_model_basics.html
       description: This guide covers the use of model classes without Active Record.
       work_in_progress: true
@@ -74,7 +74,7 @@
     -
       name: Rails Internationalization API
       url: i18n.html
-      description: This guide covers how to add internationalization to your applications. Your application will be able to translate content to different languages, change pluralization rules, use correct date formats for each country and so on.
+      description: This guide covers how to add internationalization to your applications. Your application will be able to translate content to different languages, change pluralization rules, use correct date formats for each country, and so on.
     -
       name: Action Mailer Basics
       url: action_mailer_basics.html
@@ -82,7 +82,7 @@
     -
       name: Active Job Basics
       url: active_job_basics.html
-      description: This guide provides you with all you need to get started in creating, enqueueing and executing background jobs.
+      description: This guide provides you with all you need to get started creating, enqueuing, and executing background jobs.
     -
       name: Testing Rails Applications
       work_in_progress: true
@@ -116,12 +116,16 @@
       name: The Rails Initialization Process
       work_in_progress: true
       url: initialization.html
-      description: This guide explains the internals of the Rails initialization process as of Rails 4
+      description: This guide explains the internals of the Rails initialization process as of Rails 4.
     -
       name: Autoloading and Reloading Constants
       url: autoloading_and_reloading_constants.html
       description: This guide documents how autoloading and reloading constants work.
     -
+      name: "Caching with Rails: An Overview"
+      url: caching_with_rails.html
+      description: This guide is an introduction to speeding up your Rails application with caching.
+    -
       name: Active Support Instrumentation
       work_in_progress: true
       url: active_support_instrumentation.html
diff --git a/guides/source/engines.md b/guides/source/engines.md
index 6eb558885f..f961b799f1 100644
--- a/guides/source/engines.md
+++ b/guides/source/engines.md
@@ -150,7 +150,7 @@ When you include the engine into an application later on, you will do so with
 this line in the Rails application's `Gemfile`:
 
 ```ruby
-gem 'blorgh', path: "vendor/engines/blorgh"
+gem 'blorgh', path: 'engines/blorgh'
 ```
 
 Don't forget to run `bundle install` as usual. By specifying it as a gem within
@@ -368,7 +368,7 @@ called `Blorgh::ArticlesController` (at
 `app/controllers/blorgh/articles_controller.rb`) and its related views at
 `app/views/blorgh/articles`. This generator also generates a test for the
 controller (`test/controllers/blorgh/articles_controller_test.rb`) and a helper
-(`app/helpers/blorgh/articles_controller.rb`).
+(`app/helpers/blorgh/articles_helper.rb`).
 
 Everything this generator has created is neatly namespaced. The controller's
 class is defined within the `Blorgh` module:
@@ -402,15 +402,6 @@ Finally, the assets for this resource are generated in two files:
 `app/assets/stylesheets/blorgh/articles.css`. You'll see how to use these a little
 later.
 
-By default, the scaffold styling is not applied to the engine because the
-engine's layout file, `app/views/layouts/blorgh/application.html.erb`, doesn't
-load it. To make the scaffold styling apply, insert this line into the `<head>`
-tag of this layout:
-
-```erb
-<%= stylesheet_link_tag "scaffold" %>
-```
-
 You can see what the engine has so far by running `rake db:migrate` at the root
 of our engine to run the migration generated by the scaffold generator, and then
 running `rails server` in `test/dummy`. When you open
@@ -591,7 +582,7 @@ the comments, however, is not quite right yet. If you were to create a comment
 right now, you would see this error:
 
 ```
-Missing partial blorgh/comments/comment with {:handlers=>[:erb, :builder],
+Missing partial blorgh/comments/_comment with {:handlers=>[:erb, :builder],
 :formats=>[:html], :locale=>[:en, :en]}. Searched in:   *
 "/Users/ryan/Sites/side_projects/blorgh/test/dummy/app/views"   *
 "/Users/ryan/Sites/side_projects/blorgh/app/views"
@@ -600,7 +591,7 @@ Missing partial blorgh/comments/comment with {:handlers=>[:erb, :builder],
 The engine is unable to find the partial required for rendering the comments.
 Rails looks first in the application's (`test/dummy`) `app/views` directory and
 then in the engine's `app/views` directory. When it can't find it, it will throw
-this error. The engine knows to look for `blorgh/comments/comment` because the
+this error. The engine knows to look for `blorgh/comments/_comment` because the
 model object it is receiving is from the `Blorgh::Comment` class.
 
 This partial will be responsible for rendering just the comment text, for now.
@@ -648,7 +639,7 @@ However, because you are developing the `blorgh` engine on your local machine,
 you will need to specify the `:path` option in your `Gemfile`:
 
 ```ruby
-gem 'blorgh', path: "/path/to/blorgh"
+gem 'blorgh', path: 'engines/blorgh'
 ```
 
 Then run `bundle` to install the gem.
@@ -679,7 +670,7 @@ pre-defined path which may be customizable.
 The engine contains migrations for the `blorgh_articles` and `blorgh_comments`
 table which need to be created in the application's database so that the
 engine's models can query them correctly. To copy these migrations into the
-application use this command:
+application run the following command from the `test/dummy` directory of your Rails engine:
 
 ```bash
 $ rake blorgh:install:migrations
@@ -698,8 +689,8 @@ haven't been copied over already. The first run for this command will output
 something such as this:
 
 ```bash
-Copied migration [timestamp_1]_create_blorgh_articles.rb from blorgh
-Copied migration [timestamp_2]_create_blorgh_comments.rb from blorgh
+Copied migration [timestamp_1]_create_blorgh_articles.blorgh.rb from blorgh
+Copied migration [timestamp_2]_create_blorgh_comments.blorgh.rb from blorgh
 ```
 
 The first timestamp (`[timestamp_1]`) will be the current time, and the second
@@ -831,11 +822,9 @@ Notice that only _one_ migration was copied over here. This is because the first
 two migrations were copied over the first time this command was run.
 
 ```
-NOTE Migration [timestamp]_create_blorgh_articles.rb from blorgh has been
-skipped. Migration with the same name already exists. NOTE Migration
-[timestamp]_create_blorgh_comments.rb from blorgh has been skipped. Migration
-with the same name already exists. Copied migration
-[timestamp]_add_author_id_to_blorgh_articles.rb from blorgh
+NOTE Migration [timestamp]_create_blorgh_articles.blorgh.rb from blorgh has been skipped. Migration with the same name already exists.
+NOTE Migration [timestamp]_create_blorgh_comments.blorgh.rb from blorgh has been skipped. Migration with the same name already exists.
+Copied migration [timestamp]_add_author_id_to_blorgh_articles.blorgh.rb from blorgh
 ```
 
 Run the migration using:
@@ -854,28 +843,10 @@ above the "Title" output inside `app/views/blorgh/articles/show.html.erb`:
 ```html+erb
 <p>
   <b>Author:</b>
-  <%= @article.author %>
+  <%= @article.author.name %>
 </p>
 ```
 
-By outputting `@article.author` using the `<%=` tag, the `to_s` method will be
-called on the object. By default, this will look quite ugly:
-
-```
-#<User:0x00000100ccb3b0>
-```
-
-This is undesirable. It would be much better to have the user's name there. To
-do this, add a `to_s` method to the `User` class within the application:
-
-```ruby
-def to_s
-  name
-end
-```
-
-Now instead of the ugly Ruby object output, the author's name will be displayed.
-
 #### Using a Controller Provided by the Application
 
 Because Rails controllers generally share code for things like authentication
@@ -890,7 +861,9 @@ engine this would be done by changing
 `app/controllers/blorgh/application_controller.rb` to look like:
 
 ```ruby
-class Blorgh::ApplicationController < ApplicationController
+module Blorgh
+  class ApplicationController < ::ApplicationController
+  end
 end
 ```
 
@@ -1199,7 +1172,7 @@ end
 ```
 
 ```ruby
-# Blorgh/lib/concerns/models/article
+# Blorgh/lib/concerns/models/article.rb
 
 module Blorgh::Concerns::Models::Article
   extend ActiveSupport::Concern
diff --git a/guides/source/form_helpers.md b/guides/source/form_helpers.md
index 4c02c99cc7..0a6e2e5dba 100644
--- a/guides/source/form_helpers.md
+++ b/guides/source/form_helpers.md
@@ -40,7 +40,9 @@ When called without arguments like this, it creates a `<form>` tag which, when s
 </form>
 ```
 
-You'll notice that the HTML contains `input` element with type `hidden`. This `input` is important, because the form cannot be successfully submitted without it. The hidden input element has name attribute of `utf8` enforces browsers to properly respect your form's character encoding and is generated for all forms whether their actions are "GET" or "POST". The second input element with name `authenticity_token` is a security feature of Rails called **cross-site request forgery protection**, and form helpers generate it for every non-GET form (provided that this security feature is enabled). You can read more about this in the [Security Guide](security.html#cross-site-request-forgery-csrf).
+You'll notice that the HTML contains an `input` element with type `hidden`. This `input` is important, because the form cannot be successfully submitted without it. The hidden input element with the name `utf8` enforces browsers to properly respect your form's character encoding and is generated for all forms whether their action is "GET" or "POST".
+
+The second input element with the name `authenticity_token` is a security feature of Rails called **cross-site request forgery protection**, and form helpers generate it for every non-GET form (provided that this security feature is enabled). You can read more about this in the [Security Guide](security.html#cross-site-request-forgery-csrf).
 
 ### A Generic Search Form
 
@@ -103,9 +105,9 @@ checkboxes, text fields, and radio buttons. These basic helpers, with names
 ending in `_tag` (such as `text_field_tag` and `check_box_tag`), generate just a
 single `<input>` element. The first parameter to these is always the name of the
 input. When the form is submitted, the name will be passed along with the form
-data, and will make its way to the `params` hash in the controller with the
-value entered by the user for that field. For example, if the form contains `<%=
-text_field_tag(:query) %>`, then you would be able to get the value of this
+data, and will make its way to the `params` in the controller with the
+value entered by the user for that field. For example, if the form contains
+`<%= text_field_tag(:query) %>`, then you would be able to get the value of this
 field in the controller with `params[:query]`.
 
 When naming inputs, Rails uses certain conventions that make it possible to submit parameters with non-scalar values such as arrays or hashes, which will also be accessible in `params`. You can read more about them in [chapter 7 of this guide](#understanding-parameter-naming-conventions). For details on the precise usage of these helpers, please refer to the [API documentation](http://api.rubyonrails.org/classes/ActionView/Helpers/FormTagHelper.html).
@@ -211,9 +213,8 @@ IMPORTANT: The search, telephone, date, time, color, datetime, datetime-local,
 month, week, URL, email, number and range inputs are HTML5 controls.
 If you require your app to have a consistent experience in older browsers,
 you will need an HTML5 polyfill (provided by CSS and/or JavaScript).
-There is definitely [no shortage of solutions for this](https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills), although a couple of popular tools at the moment are
-[Modernizr](http://www.modernizr.com/) and [yepnope](http://yepnopejs.com/),
-which provide a simple way to add functionality based on the presence of
+There is definitely [no shortage of solutions for this](https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills), although a popular tool at the moment is
+[Modernizr](https://modernizr.com/), which provides a simple way to add functionality based on the presence of
 detected HTML5 features.
 
 TIP: If you're using password input fields (for any purpose), you might want to configure your application to prevent those parameters from being logged. You can learn about this in the [Security Guide](security.html#logging).
@@ -241,7 +242,7 @@ Upon form submission the value entered by the user will be stored in `params[:pe
 
 WARNING: You must pass the name of an instance variable, i.e. `:person` or `"person"`, not an actual instance of your model object.
 
-Rails provides helpers for displaying the validation errors associated with a model object. These are covered in detail by the [Active Record Validations](./active_record_validations.html#displaying-validation-errors-in-views) guide.
+Rails provides helpers for displaying the validation errors associated with a model object. These are covered in detail by the [Active Record Validations](active_record_validations.html#displaying-validation-errors-in-views) guide.
 
 ### Binding a Form to an Object
 
@@ -282,7 +283,7 @@ The resulting HTML is:
 </form>
 ```
 
-The name passed to `form_for` controls the key used in `params` to access the form's values. Here the name is `article` and so all the inputs have names of the form `article[attribute_name]`. Accordingly, in the `create` action `params[:article]` will be a hash with keys `:title` and `:body`. You can read more about the significance of input names in the parameter_names section.
+The name passed to `form_for` controls the key used in `params` to access the form's values. Here the name is `article` and so all the inputs have names of the form `article[attribute_name]`. Accordingly, in the `create` action `params[:article]` will be a hash with keys `:title` and `:body`. You can read more about the significance of input names in the [parameter_names section](#understanding-parameter-naming-conventions).
 
 The helper methods called on the form builder are identical to the model object helpers except that it is not necessary to specify which object is being edited since this is already managed by the form builder.
 
@@ -291,8 +292,8 @@ You can create a similar binding without actually creating `<form>` tags with th
 ```erb
 <%= form_for @person, url: {action: "create"} do |person_form| %>
   <%= person_form.text_field :name %>
-  <%= fields_for @person.contact_detail do |contact_details_form| %>
-    <%= contact_details_form.text_field :phone_number %>
+  <%= fields_for @person.contact_detail do |contact_detail_form| %>
+    <%= contact_detail_form.text_field :phone_number %>
   <% end %>
 <% end %>
 ```
@@ -377,7 +378,7 @@ output:
 </form>
 ```
 
-When parsing POSTed data, Rails will take into account the special `_method` parameter and acts as if the HTTP method was the one specified inside it ("PATCH" in this example).
+When parsing POSTed data, Rails will take into account the special `_method` parameter and act as if the HTTP method was the one specified inside it ("PATCH" in this example).
 
 Making Select Boxes with Ease
 -----------------------------
@@ -441,7 +442,7 @@ Whenever Rails sees that the internal value of an option being generated matches
 
 TIP: The second argument to `options_for_select` must be exactly equal to the desired internal value. In particular if the value is the integer `2` you cannot pass `"2"` to `options_for_select` - you must pass `2`. Be aware of values extracted from the `params` hash as they are all strings.
 
-WARNING: when `:include_blank` or `:prompt` are not present, `:include_blank` is forced true if the select attribute `required` is true, display `size` is one and `multiple` is not true.
+WARNING: When `:include_blank` or `:prompt` are not present, `:include_blank` is forced true if the select attribute `required` is true, display `size` is one and `multiple` is not true.
 
 You can add arbitrary attributes to the options using hashes:
 
@@ -687,7 +688,14 @@ class LabellingFormBuilder < ActionView::Helpers::FormBuilder
 end
 ```
 
-If you reuse this frequently you could define a `labeled_form_for` helper that automatically applies the `builder: LabellingFormBuilder` option.
+If you reuse this frequently you could define a `labeled_form_for` helper that automatically applies the `builder: LabellingFormBuilder` option:
+
+```ruby
+def labeled_form_for(record, options = {}, &block)
+  options.merge! builder: LabellingFormBuilder
+  form_for record, options, &block
+end
+```
 
 The form builder used also determines what happens when you do
 
@@ -705,13 +713,6 @@ action for a Person model, `params[:person]` would usually be a hash of all the
 
 Fundamentally HTML forms don't know about any sort of structured data, all they generate is name-value pairs, where pairs are just plain strings. The arrays and hashes you see in your application are the result of some parameter naming conventions that Rails uses.
 
-TIP: You may find you can try out examples in this section faster by using the console to directly invoke Rack's parameter parser. For example,
-
-```ruby
-Rack::Utils.parse_query "name=fred&phone=0123456789"
-# => {"name"=>"fred", "phone"=>"0123456789"}
-```
-
 ### Basic Structures
 
 The two basic structures are arrays and hashes. Hashes mirror the syntax used for accessing the value in `params`. For example, if a form contains:
@@ -722,7 +723,7 @@ The two basic structures are arrays and hashes. Hashes mirror the syntax used fo
 
 the `params` hash will contain
 
-```erb
+```ruby
 {'person' => {'name' => 'Henry'}}
 ```
 
diff --git a/guides/source/generators.md b/guides/source/generators.md
index 14f451cbc9..32bbdc554a 100644
--- a/guides/source/generators.md
+++ b/guides/source/generators.md
@@ -503,6 +503,14 @@ Adds a specified source to `Gemfile`:
 add_source "http://gems.github.com"
 ```
 
+This method also takes a block:
+
+```ruby
+add_source "http://gems.github.com" do
+  gem "rspec-rails"
+end
+```
+
 ### `inject_into_file`
 
 Injects a block of code into a defined position in your file.
diff --git a/guides/source/getting_started.md b/guides/source/getting_started.md
index cc916e86d2..5700e71103 100644
--- a/guides/source/getting_started.md
+++ b/guides/source/getting_started.md
@@ -23,9 +23,12 @@ application from scratch. It does not assume that you have any prior experience
 with Rails. However, to get the most out of it, you need to have some
 prerequisites installed:
 
-* The [Ruby](https://www.ruby-lang.org/en/downloads) language version 1.9.3 or newer.
-* The [RubyGems](https://rubygems.org) packaging system, which is installed with Ruby
-  versions 1.9 and later. To learn more about RubyGems, please read the [RubyGems Guides](http://guides.rubygems.org).
+* The [Ruby](https://www.ruby-lang.org/en/downloads) language version 2.2.2 or newer.
+* Right version of [Development Kit](http://rubyinstaller.org/downloads/), if you
+  are using Windows.
+* The [RubyGems](https://rubygems.org) packaging system, which is installed with
+  Ruby by default. To learn more about RubyGems, please read the
+  [RubyGems Guides](http://guides.rubygems.org).
 * A working installation of the [SQLite3 Database](https://www.sqlite.org).
 
 Rails is a web application framework running on the Ruby programming language.
@@ -34,7 +37,6 @@ curve diving straight into Rails. There are several curated lists of online reso
 for learning Ruby:
 
 * [Official Ruby Programming Language website](https://www.ruby-lang.org/en/documentation/)
-* [reSRC's List of Free Programming Books](http://resrc.io/list/10/list-of-free-programming-books/#ruby)
 
 Be aware that some resources, while still excellent, cover versions of Ruby as old as
 1.6, and commonly 1.8, and will not include some syntax that you will see in day-to-day
@@ -50,7 +52,7 @@ code while accomplishing more than many other languages and frameworks.
 Experienced Rails developers also report that it makes web application
 development more fun.
 
-Rails is opinionated software. It makes the assumption that there is the "best"
+Rails is opinionated software. It makes the assumption that there is a "best"
 way to do things, and it's designed to encourage that way - and in some cases to
 discourage alternatives. If you learn "The Rails Way" you'll probably discover a
 tremendous increase in productivity. If you persist in bringing old habits from
@@ -69,10 +71,9 @@ The Rails philosophy includes two major guiding principles:
 
 Creating a New Rails Project
 ----------------------------
-
-The best way to use this guide is to follow each step as it happens, no code or
-step needed to make this example application has been left out, so you can
-literally follow along step by step.
+The best way to read this guide is to follow it step by step. All steps are
+essential to run this example application and no additional code or steps are
+needed.
 
 By following along with this guide, you'll create a Rails project called
 `blog`, a (very) simple weblog. Before you can start building the application,
@@ -89,17 +90,17 @@ Open up a command line prompt. On Mac OS X open Terminal.app, on Windows choose
 dollar sign `$` should be run in the command line. Verify that you have a
 current version of Ruby installed:
 
+```bash
+$ ruby -v
+ruby 2.2.2p95
+```
+
 TIP: A number of tools exist to help you quickly install Ruby and Ruby
 on Rails on your system. Windows users can use [Rails Installer](http://railsinstaller.org),
 while Mac OS X users can use [Tokaido](https://github.com/tokaido/tokaidoapp).
 For more installation methods for most Operating Systems take a look at
 [ruby-lang.org](https://www.ruby-lang.org/en/documentation/installation/).
 
-```bash
-$ ruby -v
-ruby 2.0.0p353
-```
-
 Many popular UNIX-like OSes ship with an acceptable version of SQLite3.
 On Windows, if you installed Rails through Rails Installer, you
 already have SQLite installed. Others can find installation instructions
@@ -163,7 +164,7 @@ of the files and folders that Rails created by default:
 | File/Folder | Purpose |
 | ----------- | ------- |
 |app/|Contains the controllers, models, views, helpers, mailers and assets for your application. You'll focus on this folder for the remainder of this guide.|
-|bin/|Contains the rails script that starts your app and can contain other scripts you use to setup, deploy or run your application.|
+|bin/|Contains the rails script that starts your app and can contain other scripts you use to setup, update, deploy or run your application.|
 |config/|Configure your application's routes, database, and more. This is covered in more detail in [Configuring Rails Applications](configuring.html).|
 |config.ru|Rack configuration for Rack based servers used to start the application.|
 |db/|Contains your current database schema, as well as the database migrations.|
@@ -193,6 +194,9 @@ following in the `blog` directory:
 $ bin/rails server
 ```
 
+TIP: If you are using Windows, you have to pass the scripts under the `bin`
+folder directly to the Ruby interpreter e.g. `ruby bin\rails server`.
+
 TIP: Compiling CoffeeScript and JavaScript asset compression requires you
 have a JavaScript runtime available on your system, in the absence
 of a runtime you will see an `execjs` error during asset compilation.
@@ -201,7 +205,7 @@ Rails adds the `therubyracer` gem to the generated `Gemfile` in a
 commented line for new apps and you can uncomment if you need it.
 `therubyrhino` is the recommended runtime for JRuby users and is added by
 default to the `Gemfile` in apps generated under JRuby. You can investigate
-all the supported runtimes at [ExecJS](https://github.com/sstephenson/execjs#readme).
+all the supported runtimes at [ExecJS](https://github.com/rails/execjs#readme).
 
 This will fire up WEBrick, a web server distributed with Ruby by default. To see
 your application in action, open a browser window and navigate to
@@ -295,6 +299,7 @@ Rails.application.routes.draw do
 
   # The priority is based upon order of creation:
   # first created -> highest priority.
+  # See how all your routes lay out with "rake routes".
   #
   # You can have the root of your site routed with "root"
   # root 'welcome#index'
@@ -318,9 +323,9 @@ root 'welcome#index'
 application to the welcome controller's index action and `get 'welcome/index'`
 tells Rails to map requests to <http://localhost:3000/welcome/index> to the
 welcome controller's index action. This was created earlier when you ran the
-controller generator (`rails generate controller welcome index`).
+controller generator (`bin/rails generate controller welcome index`).
 
-Launch the web server again if you stopped it to generate the controller (`rails
+Launch the web server again if you stopped it to generate the controller (`bin/rails
 server`) and navigate to <http://localhost:3000> in your browser. You'll see the
 "Hello, Rails!" message you put into `app/views/welcome/index.html.erb`,
 indicating that this new route is indeed going to `WelcomeController`'s `index`
@@ -353,7 +358,7 @@ Rails.application.routes.draw do
 end
 ```
 
-If you run `rake routes`, you'll see that it has defined routes for all the
+If you run `bin/rake routes`, you'll see that it has defined routes for all the
 standard RESTful actions.  The meaning of the prefix column (and other columns)
 will be seen later, but for now notice that Rails has inferred the
 singular form `article` and makes meaningful use of the distinction.
@@ -374,7 +379,7 @@ edit_article GET    /articles/:id/edit(.:format) articles#edit
 
 In the next section, you will add the ability to create new articles in your
 application and be able to view them. This is the "C" and the "R" from CRUD:
-creation and reading. The form for doing this will look like this:
+create and read. The form for doing this will look like this:
 
 ![The new article form](images/getting_started/new_article.png)
 
@@ -397,7 +402,7 @@ a controller called `ArticlesController`. You can do this by running this
 command:
 
 ```bash
-$ bin/rails g controller articles
+$ bin/rails generate controller articles
 ```
 
 If you open up the newly generated `app/controllers/articles_controller.rb`
@@ -553,7 +558,7 @@ this:
 
 In this example, the `articles_path` helper is passed to the `:url` option.
 To see what Rails will do with this, we look back at the output of
-`rake routes`:
+`bin/rake routes`:
 
 ```bash
 $ bin/rake routes
@@ -616,7 +621,7 @@ def create
 end
 ```
 
-The `render` method here is taking a very simple hash with a key of `plain` and
+The `render` method here is taking a very simple hash with a key of `:plain` and
 value of `params[:article].inspect`. The `params` method is the object which
 represents the parameters (or fields) coming in from the form. The `params`
 method returns an `ActiveSupport::HashWithIndifferentAccess` object, which
@@ -663,7 +668,7 @@ models, as that will be done automatically by Active Record.
 
 ### Running a Migration
 
-As we've just seen, `rails generate model` created a _database migration_ file
+As we've just seen, `bin/rails generate model` created a _database migration_ file
 inside the `db/migrate` directory. Migrations are Ruby classes that are
 designed to make it simple to create and modify database tables. Rails uses
 rake commands to run migrations, and it's possible to undo a migration after
@@ -716,7 +721,7 @@ NOTE. Because you're working in the development environment by default, this
 command will apply to the database defined in the `development` section of your
 `config/database.yml` file. If you would like to execute migrations in another
 environment, for instance in production, you must explicitly pass it when
-invoking the command: `rake db:migrate RAILS_ENV=production`.
+invoking the command: `bin/rake db:migrate RAILS_ENV=production`.
 
 ### Saving data in the controller
 
@@ -803,7 +808,7 @@ If you submit the form again now, Rails will complain about not finding the
 `show` action. That's not very useful though, so let's add the `show` action
 before proceeding.
 
-As we have seen in the output of `rake routes`, the route for `show` action is
+As we have seen in the output of `bin/rake routes`, the route for `show` action is
 as follows:
 
 ```
@@ -833,7 +838,7 @@ class ArticlesController < ApplicationController
   def new
   end
 
-  # snipped for brevity
+  # snippet for brevity
 ```
 
 A couple of things to note. We use `Article.find` to find the article we're
@@ -865,7 +870,7 @@ Visit <http://localhost:3000/articles/new> and give it a try!
 ### Listing all articles
 
 We still need a way to list all our articles, so let's do that.
-The route for this as per output of `rake routes` is:
+The route for this as per output of `bin/rake routes` is:
 
 ```
 articles GET    /articles(.:format)          articles#index
@@ -889,7 +894,7 @@ class ArticlesController < ApplicationController
   def new
   end
 
-  # snipped for brevity
+  # snippet for brevity
 ```
 
 And then finally, add the view for this action, located at
@@ -908,6 +913,7 @@ And then finally, add the view for this action, located at
     <tr>
       <td><%= article.title %></td>
       <td><%= article.text %></td>
+      <td><%= link_to 'Show', article_path(article) %></td>
     </tr>
   <% end %>
 </table>
@@ -1236,10 +1242,9 @@ article we want to show the form back to the user.
 We reuse the `article_params` method that we defined earlier for the create
 action.
 
-TIP: You don't need to pass all attributes to `update`. For
-example, if you'd call `@article.update(title: 'A new title')`
-Rails would only update the `title` attribute, leaving all other
-attributes untouched.
+TIP: It is not necessary to pass all the attributes to `update`. For example,
+if `@article.update(title: 'A new title')` was called, Rails would only update
+the `title` attribute, leaving all other attributes untouched.
 
 Finally, we want to show a link to the `edit` action in the list of all the
 articles, so let's add that now to `app/views/articles/index.html.erb` to make
@@ -1271,8 +1276,8 @@ bottom of the template:
 ```html+erb
 ...
 
-<%= link_to 'Back', articles_path %> |
-<%= link_to 'Edit', edit_article_path(@article) %>
+<%= link_to 'Edit', edit_article_path(@article) %> |
+<%= link_to 'Back', articles_path %>
 ```
 
 And here's how our app looks so far:
@@ -1359,7 +1364,7 @@ Then do the same for the `app/views/articles/edit.html.erb` view:
 
 We're now ready to cover the "D" part of CRUD, deleting articles from the
 database. Following the REST convention, the route for
-deleting articles as per output of `rake routes` is:
+deleting articles as per output of `bin/rake routes` is:
 
 ```ruby
 DELETE /articles/:id(.:format)      articles#destroy
@@ -1475,18 +1480,19 @@ Finally, add a 'Destroy' link to your `index` action template
 ```
 
 Here we're using `link_to` in a different way. We pass the named route as the
-second argument, and then the options as another argument. The `:method` and
-`:'data-confirm'` options are used as HTML5 attributes so that when the link is
-clicked, Rails will first show a confirm dialog to the user, and then submit the
-link with method `delete`.  This is done via the JavaScript file `jquery_ujs`
-which is automatically included into your application's layout
-(`app/views/layouts/application.html.erb`) when you generated the application.
-Without this file, the confirmation dialog box wouldn't appear.
+second argument, and then the options as another argument. The `method: :delete`
+and `data: { confirm: 'Are you sure?' }` options are used as HTML5 attributes so
+that when the link is clicked, Rails will first show a confirm dialog to the
+user, and then submit the link with method `delete`.  This is done via the
+JavaScript file `jquery_ujs` which is automatically included in your
+application's layout (`app/views/layouts/application.html.erb`) when you
+generated the application. Without this file, the confirmation dialog box won't
+appear.
 
 ![Confirm Dialog](images/getting_started/confirm_dialog.png)
 
 TIP: Learn more about jQuery Unobtrusive Adapter (jQuery UJS) on
-[Working With Javascript in Rails](working_with_javascript_in_rails.html) guide.
+[Working With JavaScript in Rails](working_with_javascript_in_rails.html) guide.
 
 Congratulations, you can now create, show, list, update and destroy
 articles.
@@ -1505,7 +1511,7 @@ comments on articles.
 
 We're going to see the same generator that we used before when creating
 the `Article` model. This time we'll create a `Comment` model to hold
-reference of article comments. Run this command in your terminal:
+reference to an article. Run this command in your terminal:
 
 ```bash
 $ bin/rails generate model Comment commenter:string body:text article:references
@@ -1517,7 +1523,7 @@ This command will generate four files:
 | -------------------------------------------- | ------------------------------------------------------------------------------------------------------ |
 | db/migrate/20140120201010_create_comments.rb | Migration to create the comments table in your database (your name will include a different timestamp) |
 | app/models/comment.rb                        | The Comment model                                                                                      |
-| test/models/comment_test.rb                  | Testing harness for the comments model                                                                 |
+| test/models/comment_test.rb                  | Testing harness for the comment model                                                                 |
 | test/fixtures/comments.yml                   | Sample comments for use in testing                                                                     |
 
 First, take a look at `app/models/comment.rb`:
@@ -1541,20 +1547,17 @@ class CreateComments < ActiveRecord::Migration
     create_table :comments do |t|
       t.string :commenter
       t.text :body
-
-      # this line adds an integer column called `article_id`.
-      t.references :article, index: true
+      t.references :article, index: true, foreign_key: true
 
       t.timestamps null: false
     end
-    add_foreign_key :comments, :articles
   end
 end
 ```
 
-The `t.references` line sets up a foreign key column for the association between
-the two models. An index for this association is also created on this column.
-Go ahead and run the migration:
+The `t.references` line creates an integer column called `article_id`, an index
+for it, and a foreign key constraint that points to the `id` column of the `articles`
+table. Go ahead and run the migration:
 
 ```bash
 $ bin/rake db:migrate
@@ -1567,8 +1570,6 @@ run against the current database, so in this case you will just see:
 ==  CreateComments: migrating =================================================
 -- create_table(:comments)
    -> 0.0115s
--- add_foreign_key(:comments, :articles)
-   -> 0.0000s
 ==  CreateComments: migrated (0.0119s) ========================================
 ```
 
@@ -1684,8 +1685,8 @@ So first, we'll wire up the Article show template
   </p>
 <% end %>
 
-<%= link_to 'Back', articles_path %> |
-<%= link_to 'Edit', edit_article_path(@article) %>
+<%= link_to 'Edit', edit_article_path(@article) %> |
+<%= link_to 'Back', articles_path %>
 ```
 
 This adds a form on the `Article` show page that creates a new comment by
@@ -1765,8 +1766,8 @@ add that to the `app/views/articles/show.html.erb`.
   </p>
 <% end %>
 
-<%= link_to 'Edit Article', edit_article_path(@article) %> |
-<%= link_to 'Back to Articles', articles_path %>
+<%= link_to 'Edit', edit_article_path(@article) %> |
+<%= link_to 'Back', articles_path %>
 ```
 
 Now you can add articles and comments to your blog and have them show up in the
@@ -1831,8 +1832,8 @@ following:
   </p>
 <% end %>
 
-<%= link_to 'Edit Article', edit_article_path(@article) %> |
-<%= link_to 'Back to Articles', articles_path %>
+<%= link_to 'Edit', edit_article_path(@article) %> |
+<%= link_to 'Back', articles_path %>
 ```
 
 This will now render the partial in `app/views/comments/_comment.html.erb` once
@@ -1881,8 +1882,8 @@ Then you make the `app/views/articles/show.html.erb` look like the following:
 <h2>Add a comment:</h2>
 <%= render 'comments/form' %>
 
-<%= link_to 'Edit Article', edit_article_path(@article) %> |
-<%= link_to 'Back to Articles', articles_path %>
+<%= link_to 'Edit', edit_article_path(@article) %> |
+<%= link_to 'Back', articles_path %>
 ```
 
 The second render just defines the partial template we want to render,
@@ -1998,7 +1999,7 @@ class ArticlesController < ApplicationController
     @articles = Article.all
   end
 
-  # snipped for brevity
+  # snippet for brevity
 ```
 
 We also want to allow only authenticated users to delete comments, so in the
@@ -2014,7 +2015,7 @@ class CommentsController < ApplicationController
     # ...
   end
 
-  # snipped for brevity
+  # snippet for brevity
 ```
 
 Now if you try to create a new article, you will be greeted with a basic HTTP
@@ -2051,19 +2052,6 @@ resources:
 * The [Ruby on Rails mailing list](http://groups.google.com/group/rubyonrails-talk)
 * The [#rubyonrails](irc://irc.freenode.net/#rubyonrails) channel on irc.freenode.net
 
-Rails also comes with built-in help that you can generate using the rake
-command-line utility:
-
-* Running `rake doc:guides` will put a full copy of the Rails Guides in the
-  `doc/guides` folder of your application. Open `doc/guides/index.html` in your
-  web browser to explore the Guides.
-* Running `rake doc:rails` will put a full copy of the API documentation for
-  Rails in the `doc/api` folder of your application. Open `doc/api/index.html`
-  in your web browser to explore the API documentation.
-
-TIP: To be able to generate the Rails Guides locally with the `doc:guides` rake
-task you need to install the Redcarpet and Nokogiri gems. Add it to your `Gemfile` and run
-`bundle install` and you're ready to go.
 
 Configuration Gotchas
 ---------------------
diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index 779526d733..87d2fafaf3 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -40,7 +40,7 @@ Internationalization is a complex problem. Natural languages differ in so many w
 * providing support for English and similar languages out of the box
 * making it easy to customize and extend everything for other languages
 
-As part of this solution, **every static string in the Rails framework** - e.g. Active Record validation messages, time and date formats - **has been internationalized**, so _localization_ of a Rails application means "over-riding" these defaults.
+As part of this solution, **every static string in the Rails framework** - e.g. Active Record validation messages, time and date formats - **has been internationalized**. _Localization_ of a Rails application means defining translated values for these strings in desired languages.
 
 ### The Overall Architecture of the Library
 
@@ -51,7 +51,7 @@ Thus, the Ruby I18n gem is split into two parts:
 
 As a user you should always only access the public methods on the I18n module, but it is useful to know about the capabilities of the backend.
 
-NOTE: It is possible (or even desirable) to swap the shipped Simple backend with a more powerful one, which would store translation data in a relational database, GetText dictionary, or similar. See section [Using different backends](#using-different-backends) below.
+NOTE: It is possible to swap the shipped Simple backend with a more powerful one, which would store translation data in a relational database, GetText dictionary, or similar. See section [Using different backends](#using-different-backends) below.
 
 ### The Public I18n API
 
@@ -84,13 +84,13 @@ So, let's internationalize a simple Rails application from the ground up in the
 Setup the Rails Application for Internationalization
 ----------------------------------------------------
 
-There are just a few simple steps to get up and running with I18n support for your application.
+There are a few steps to get up and running with I18n support for a Rails application.
 
 ### Configure the I18n Module
 
-Following the _convention over configuration_ philosophy, Rails will set up your application with reasonable defaults. If you need different settings, you can overwrite them easily.
+Following the _convention over configuration_ philosophy, Rails I18n provides reasonable default translation strings. When different translation strings are needed, they can be overridden.
 
-Rails adds all `.rb` and `.yml` files from the `config/locales` directory to your **translations load path**, automatically.
+Rails adds all `.rb` and `.yml` files from the `config/locales` directory to the **translations load path**, automatically.
 
 The default `en.yml` locale in this directory contains a sample pair of translation strings:
 
@@ -101,15 +101,15 @@ en:
 
 This means, that in the `:en` locale, the key _hello_ will map to the _Hello world_ string. Every string inside Rails is internationalized in this way, see for instance Active Model validation messages in the [`activemodel/lib/active_model/locale/en.yml`](https://github.com/rails/rails/blob/master/activemodel/lib/active_model/locale/en.yml) file or time and date formats in the [`activesupport/lib/active_support/locale/en.yml`](https://github.com/rails/rails/blob/master/activesupport/lib/active_support/locale/en.yml) file. You can use YAML or standard Ruby Hashes to store translations in the default (Simple) backend.
 
-The I18n library will use **English** as a **default locale**, i.e. if you don't set a different locale, `:en` will be used for looking up translations.
+The I18n library will use **English** as a **default locale**, i.e. if a different locale is not set, `:en` will be used for looking up translations.
 
 NOTE: The i18n library takes a **pragmatic approach** to locale keys (after [some discussion](http://groups.google.com/group/rails-i18n/browse_thread/thread/14dede2c7dbe9470/80eec34395f64f3c?hl=en)), including only the _locale_ ("language") part, like `:en`, `:pl`, not the _region_ part, like `:en-US` or `:en-GB`, which are traditionally used for separating "languages" and "regional setting" or "dialects". Many international applications use only the "language" element of a locale such as `:cs`, `:th` or `:es` (for Czech, Thai and Spanish). However, there are also regional differences within different language groups that may be important. For instance, in the `:en-US` locale you would have $ as a currency symbol, while in `:en-GB`, you would have £. Nothing stops you from separating regional and other settings in this way: you just have to provide full "English - United Kingdom" locale in a `:en-GB` dictionary. Few gems such as [Globalize3](https://github.com/globalize/globalize) may help you implement it.
 
-The **translations load path** (`I18n.load_path`) is just a Ruby Array of paths to your translation files that will be loaded automatically and available in your application. You can pick whatever directory and translation file naming scheme makes sense for you.
+The **translations load path** (`I18n.load_path`) is an array of paths to files that will be loaded automatically. Configuring this path allows for customization of translations directory structure and file naming scheme.
 
-NOTE: The backend will lazy-load these translations when a translation is looked up for the first time. This makes it possible to just swap the backend with something else even after translations have already been announced.
+NOTE: The backend lazy-loads these translations when a translation is looked up for the first time. This backend can be swapped with something else even after translations have already been announced.
 
-The default `application.rb` file has instructions on how to add locales from another directory and how to set a different default locale. Just uncomment and edit the specific lines.
+The default `config/application.rb` file has instructions on how to add locales from another directory and how to set a different default locale.
 
 ```ruby
 # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
@@ -117,31 +117,25 @@ The default `application.rb` file has instructions on how to add locales from an
 # config.i18n.default_locale = :de
 ```
 
-### Optional: Custom I18n Configuration Setup
-
-For the sake of completeness, let's mention that if you do not want to use the `application.rb` file for some reason, you can always wire up things manually, too.
-
-To tell the I18n library where it can find your custom translation files you can specify the load path anywhere in your application - just make sure it gets run before any translations are actually looked up. You might also want to change the default locale. The simplest thing possible is to put the following into an initializer:
+The load path must be specified before any translations are looked up. To change the default locale from an initializer instead of `config/application.rb`:
 
 ```ruby
-# in config/initializers/locale.rb
+# config/initializers/locale.rb
 
-# tell the I18n library where to find your translations
+# Where the I18n library should search for translation files
 I18n.load_path += Dir[Rails.root.join('lib', 'locale', '*.{rb,yml}')]
 
-# set default locale to something other than :en
+# Set default locale to something other than :en
 I18n.default_locale = :pt
 ```
 
-### Setting and Passing the Locale
-
-If you want to translate your Rails application to a **single language other than English** (the default locale), you can set I18n.default_locale to your locale in `application.rb` or an initializer as shown above, and it will persist through the requests.
+### Managing the Locale across Requests
 
-However, you would probably like to **provide support for more locales** in your application. In such case, you need to set and pass the locale between requests.
+The default locale is used for all translations unless `I18n.locale` is explicitly set.
 
-WARNING: You may be tempted to store the chosen locale in a _session_ or a *cookie*. However, **do not do this**. The locale should be transparent and a part of the URL. This way you won't break people's basic assumptions about the web itself: if you send a URL to a friend, they should see the same page and content as you. A fancy word for this would be that you're being [*RESTful*](http://en.wikipedia.org/wiki/Representational_State_Transfer). Read more about the RESTful approach in [Stefan Tilkov's articles](http://www.infoq.com/articles/rest-introduction). Sometimes there are exceptions to this rule and those are discussed below.
+A localized application will likely need to provide support for multiple locales. To accomplish this, the locale should be set at the beginning of each request so that all strings are translated using the desired locale during the lifetime of that request.
 
-The _setting part_ is easy. You can set the locale in a `before_action` in the `ApplicationController` like this:
+The locale can be set in a `before_action` in the `ApplicationController`:
 
 ```ruby
 before_action :set_locale
@@ -151,11 +145,11 @@ def set_locale
 end
 ```
 
-This requires you to pass the locale as a URL query parameter as in `http://example.com/books?locale=pt`. (This is, for example, Google's approach.) So `http://localhost:3000?locale=pt` will load the Portuguese localization, whereas `http://localhost:3000?locale=de` would load the German localization, and so on. You may skip the next section and head over to the **Internationalize your application** section, if you want to try things out by manually placing the locale in the URL and reloading the page.
+This example illustrates this using a URL query parameter to set the locale (e.g. `http://example.com/books?locale=pt`). With this approach, `http://localhost:3000?locale=pt` renders the Portuguese localization, while `http://localhost:3000?locale=de` loads a German localization.
 
-Of course, you probably don't want to manually include the locale in every URL all over your application, or want the URLs look differently, e.g. the usual `http://example.com/pt/books` versus `http://example.com/en/books`. Let's discuss the different options you have.
+The locale can be set using one of many different approaches.
 
-### Setting the Locale from the Domain Name
+#### Setting the Locale from the Domain Name
 
 One option you have is to set the locale from the domain name where your application runs. For example, we want `www.example.com` to load the English (or default) locale, and `www.example.es` to load the Spanish locale. Thus the _top-level domain name_ is used for locale setting. This has several advantages:
 
@@ -201,14 +195,14 @@ end
 If your application includes a locale switching menu, you would then have something like this in it:
 
 ```ruby
-link_to("Deutsch", "#{APP_CONFIG[:deutsch_website_url]}#{request.env['REQUEST_URI']}")
+link_to("Deutsch", "#{APP_CONFIG[:deutsch_website_url]}#{request.env['PATH_INFO']}")
 ```
 
 assuming you would set `APP_CONFIG[:deutsch_website_url]` to some value like `http://www.application.de`.
 
 This solution has aforementioned advantages, however, you may not be able or may not want to provide different localizations ("language versions") on different domains. The most obvious solution would be to include locale code in the URL params (or request path).
 
-### Setting the Locale from the URL Params
+#### Setting the Locale from URL Params
 
 The most usual way of setting (and passing) the locale would be to include it in URL params, as we did in the `I18n.locale = params[:locale]` _before_action_ in the first example. We would like to have URLs like `www.example.com/books?locale=ja` or `www.example.com/ja/books` in this case.
 
@@ -216,14 +210,14 @@ This approach has almost the same set of advantages as setting the locale from t
 
 Getting the locale from `params` and setting it accordingly is not hard; including it in every URL and thus **passing it through the requests** is. To include an explicit option in every URL, e.g. `link_to(books_url(locale: I18n.locale))`, would be tedious and probably impossible, of course.
 
-Rails contains infrastructure for "centralizing dynamic decisions about the URLs" in its [`ApplicationController#default_url_options`](http://api.rubyonrails.org/classes/ActionDispatch/Routing/Mapper/Base.html#method-i-default_url_options), which is useful precisely in this scenario: it enables us to set "defaults" for [`url_for`](http://api.rubyonrails.org/classes/ActionDispatch/Routing/UrlFor.html#method-i-url_for) and helper methods dependent on it (by implementing/overriding this method).
+Rails contains infrastructure for "centralizing dynamic decisions about the URLs" in its [`ApplicationController#default_url_options`](http://api.rubyonrails.org/classes/ActionDispatch/Routing/Mapper/Base.html#method-i-default_url_options), which is useful precisely in this scenario: it enables us to set "defaults" for [`url_for`](http://api.rubyonrails.org/classes/ActionDispatch/Routing/UrlFor.html#method-i-url_for) and helper methods dependent on it (by implementing/overriding `default_url_options`).
 
 We can include something like this in our `ApplicationController` then:
 
 ```ruby
 # app/controllers/application_controller.rb
-def default_url_options(options = {})
-  { locale: I18n.locale }.merge options
+def default_url_options
+  { locale: I18n.locale }
 end
 ```
 
@@ -231,7 +225,7 @@ Every helper method dependent on `url_for` (e.g. helpers for named routes like `
 
 You may be satisfied with this. It does impact the readability of URLs, though, when the locale "hangs" at the end of every URL in your application. Moreover, from the architectural standpoint, locale is usually hierarchically above the other parts of the application domain: and URLs should reflect this.
 
-You probably want URLs to look like this: `www.example.com/en/books` (which loads the English locale) and `www.example.com/nl/books` (which loads the Dutch locale). This is achievable with the "over-riding `default_url_options`" strategy from above: you just have to set up your routes with [`scoping`](http://api.rubyonrails.org/classes/ActionDispatch/Routing/Mapper/Scoping.html) option in this way:
+You probably want URLs to look like this: `http://www.example.com/en/books` (which loads the English locale) and `http://www.example.com/nl/books` (which loads the Dutch locale). This is achievable with the "over-riding `default_url_options`" strategy from above: you just have to set up your routes with [`scope`](http://api.rubyonrails.org/classes/ActionDispatch/Routing/Mapper/Scoping.html):
 
 ```ruby
 # config/routes.rb
@@ -240,7 +234,9 @@ scope "/:locale" do
 end
 ```
 
-Now, when you call the `books_path` method you should get `"/en/books"` (for the default locale). An URL like `http://localhost:3001/nl/books` should load the Dutch locale, then, and following calls to `books_path` should return `"/nl/books"` (because the locale changed).
+Now, when you call the `books_path` method you should get `"/en/books"` (for the default locale). A URL like `http://localhost:3001/nl/books` should load the Dutch locale, then, and following calls to `books_path` should return `"/nl/books"` (because the locale changed).
+
+WARNING. Since the return value of `default_url_options` is cached per request, the URLs in a locale selector cannot be generated invoking helpers in a loop that sets the corresponding `I18n.locale` in each iteration. Instead, leave `I18n.locale` untouched, and pass an explicit `:locale` option to the helper, or edit `request.original_fullpath`.
 
 If you don't want to force the use of a locale in your routes you can use an optional path scope (denoted by the parentheses) like so:
 
@@ -253,7 +249,7 @@ end
 
 With this approach you will not get a `Routing Error` when accessing your resources such as `http://localhost:3001/books` without a locale. This is useful for when you want to use the default locale when one is not specified.
 
-Of course, you need to take special care of the root URL (usually "homepage" or "dashboard") of your application. An URL like `http://localhost:3001/nl` will not work automatically, because the `root to: "books#index"` declaration in your `routes.rb` doesn't take locale into account. (And rightly so: there's only one "root" URL.)
+Of course, you need to take special care of the root URL (usually "homepage" or "dashboard") of your application. A URL like `http://localhost:3001/nl` will not work automatically, because the `root to: "books#index"` declaration in your `routes.rb` doesn't take locale into account. (And rightly so: there's only one "root" URL.)
 
 You would probably need to map URLs like these:
 
@@ -266,14 +262,23 @@ Do take special care about the **order of your routes**, so this route declarati
 
 NOTE: Have a look at various gems which simplify working with routes: [routing_filter](https://github.com/svenfuchs/routing-filter/tree/master), [rails-translate-routes](https://github.com/francesc/rails-translate-routes), [route_translator](https://github.com/enriclluelles/route_translator).
 
-### Setting the Locale from the Client Supplied Information
+#### Setting the Locale from User Preferences
+
+An application with authenticated users may allow users to set a locale preference through the application's interface. With this approach, a user's selected locale preference is persisted in the database and used to set the locale for authenticated requests by that user.
+
+```ruby
+def set_locale
+  I18n.locale = current_user.try(:locale) || I18n.default_locale
+end
+```
 
-In specific cases, it would make sense to set the locale from client-supplied information, i.e. not from the URL. This information may come for example from the users' preferred language (set in their browser), can be based on the users' geographical location inferred from their IP, or users can provide it simply by choosing the locale in your application interface and saving it to their profile. This approach is more suitable for web-based applications or services, not for websites - see the box about _sessions_, _cookies_ and RESTful architecture above.
+#### Choosing an Implied Locale
 
+When an explicit locale has not been set for a request (e.g. via one of the above methods), an application should attempt to infer the desired locale.
 
-#### Using `Accept-Language`
+##### Inferring Locale from the Language Header
 
-One source of client supplied information would be an `Accept-Language` HTTP header. People may [set this in their browser](http://www.w3.org/International/questions/qa-lang-priorities) or other clients (such as _curl_).
+The `Accept-Language` HTTP header indicates the preferred language for request's response. Browsers [set this header value based on the user's language preference settings](http://www.w3.org/International/questions/qa-lang-priorities), making it a good first choice when inferring a locale.
 
 A trivial implementation of using an `Accept-Language` header would be:
 
@@ -290,24 +295,27 @@ private
   end
 ```
 
-Of course, in a production environment you would need much more robust code, and could use a gem such as Iain Hecker's [http_accept_language](https://github.com/iain/http_accept_language/tree/master) or even Rack middleware such as Ryan Tomayko's [locale](https://github.com/rack/rack-contrib/blob/master/lib/rack/contrib/locale.rb).
 
-#### Using GeoIP (or Similar) Database
+In practice, more robust code is necessary to do this reliably. Iain Hecker's [http_accept_language](https://github.com/iain/http_accept_language/tree/master) library or Ryan Tomayko's [locale](https://github.com/rack/rack-contrib/blob/master/lib/rack/contrib/locale.rb) Rack middleware provide solutions to this problem.
 
-Another way of choosing the locale from client information would be to use a database for mapping the client IP to the region, such as [GeoIP Lite Country](http://www.maxmind.com/app/geolitecountry). The mechanics of the code would be very similar to the code above - you would need to query the database for the user's IP, and look up your preferred locale for the country/region/city returned.
+##### Inferring the Locale from IP Geolocation
 
-#### User Profile
+The IP address of the client making the request can be used to infer the client's region and thus their locale. Services such as [GeoIP Lite Country](http://www.maxmind.com/app/geolitecountry) or gems like [geocoder](https://github.com/alexreisner/geocoder) can be used to implement this approach.
 
-You can also provide users of your application with means to set (and possibly over-ride) the locale in your application interface, as well. Again, mechanics for this approach would be very similar to the code above - you'd probably let users choose a locale from a dropdown list and save it to their profile in the database. Then you'd set the locale to this value.
+In general, this approach is far less reliable than using the language header and is not recommended for most web applications.
 
-Internationalizing your Application
+#### Storing the Locale from the Session or Cookies
+
+WARNING: You may be tempted to store the chosen locale in a _session_ or a *cookie*. However, **do not do this**. The locale should be transparent and a part of the URL. This way you won't break people's basic assumptions about the web itself: if you send a URL to a friend, they should see the same page and content as you. A fancy word for this would be that you're being [*RESTful*](http://en.wikipedia.org/wiki/Representational_State_Transfer). Read more about the RESTful approach in [Stefan Tilkov's articles](http://www.infoq.com/articles/rest-introduction). Sometimes there are exceptions to this rule and those are discussed below.
+
+Internationalization and Localization
 -----------------------------------
 
-OK! Now you've initialized I18n support for your Ruby on Rails application and told it which locale to use and how to preserve it between requests. With that in place, you're now ready for the really interesting stuff.
+OK! Now you've initialized I18n support for your Ruby on Rails application and told it which locale to use and how to preserve it between requests.
 
-Let's _internationalize_ our application, i.e. abstract every locale-specific parts, and then _localize_ it, i.e. provide necessary translations for these abstracts.
+Next we need to _internationalize_ our application by abstracting every locale-specific element. Finally, we need to _localize_ it by providing necessary translations for these abstracts.
 
-You most probably have something like this in one of your applications:
+Given the following example:
 
 ```ruby
 # config/routes.rb
@@ -344,9 +352,9 @@ end
 
 ![rails i18n demo untranslated](images/i18n/demo_untranslated.png)
 
-### Adding Translations
+### Abstracting Localized Code
 
-Obviously there are **two strings that are localized to English**. In order to internationalize this code, **replace these strings** with calls to Rails' `#t` helper with a key that makes sense for the translation:
+There are two strings in our code that are in English and that users will be rendered in our response ("Hello Flash" and "Hello World"). In order to internationalize this code, these strings need to be replaced by calls to Rails' `#t` helper with an appropriate key for each string:
 
 ```ruby
 # app/controllers/home_controller.rb
@@ -363,13 +371,15 @@ end
 <p><%= flash[:notice] %></p>
 ```
 
-When you now render this view, it will show an error message which tells you that the translations for the keys `:hello_world` and `:hello_flash` are missing.
+Now, when this view is rendered, it will show an error message which tells you that the translations for the keys `:hello_world` and `:hello_flash` are missing.
 
 ![rails i18n demo translation missing](images/i18n/demo_translation_missing.png)
 
 NOTE: Rails adds a `t` (`translate`) helper method to your views so that you do not need to spell out `I18n.t` all the time. Additionally this helper will catch missing translations and wrap the resulting error message into a `<span class="translation_missing">`.
 
-So let's add the missing translations into the dictionary files (i.e. do the "localization" part):
+### Providing Translations for Internationalized Strings
+
+Add the missing translations into the translation dictionary files:
 
 ```yaml
 # config/locales/en.yml
@@ -383,11 +393,11 @@ pirate:
   hello_flash: Ahoy Flash
 ```
 
-There you go. Because you haven't changed the default_locale, I18n will use English. Your application now shows:
+Because the `default_locale` hasn't changed, translations use the `:en` locale and the response renders the english strings:
 
 ![rails i18n demo translated to English](images/i18n/demo_translated_en.png)
 
-And when you change the URL to pass the pirate locale (`http://localhost:3000?locale=pirate`), you'll get:
+If the locale is set via the URL to the pirate locale (`http://localhost:3000?locale=pirate`), the response renders the pirate strings:
 
 ![rails i18n demo translated to pirate](images/i18n/demo_translated_pirate.png)
 
@@ -395,21 +405,64 @@ NOTE: You need to restart the server when you add new locale files.
 
 You may use YAML (`.yml`) or plain Ruby (`.rb`) files for storing your translations in SimpleStore. YAML is the preferred option among Rails developers. However, it has one big disadvantage. YAML is very sensitive to whitespace and special characters, so the application may not load your dictionary properly. Ruby files will crash your application on first request, so you may easily find what's wrong. (If you encounter any "weird issues" with YAML dictionaries, try putting the relevant portion of your dictionary into a Ruby file.)
 
-### Passing variables to translations
+### Passing Variables to Translations
+
+One key consideration for successfully internationalizing an application is to
+avoid making incorrect assumptions about grammar rules when abstracting localized
+code. Grammar rules that seem fundamental in one locale may not hold true in
+another one.
 
-You can use variables in the translation messages and pass their values from the view.
+Improper abstraction is shown in the following example, where assumptions are
+made about the ordering of the different parts of the translation. Note that Rails
+provides a `number_to_currency` helper to handle the following case.
 
 ```erb
-# app/views/home/index.html.erb
-<%=t 'greet_username', user: "Bill", message: "Goodbye" %>
+# app/views/products/show.html.erb
+<%= "#{t('currency')}#{@product.price}" %>
 ```
 
 ```yaml
 # config/locales/en.yml
 en:
-  greet_username: "%{message}, %{user}!"
+  currency: "$"
+
+# config/locales/es.yml
+es:
+  currency: "€"
 ```
 
+If the product's price is 10 then the proper translation for Spanish is "10 €"
+instead of "€10" but the abstraction cannot give it.
+
+To create proper abstraction, the I18n gem ships with a feature called variable
+interpolation that allows you to use variables in translation definitions and
+pass the values for these variables to the translation method.
+
+Proper abstraction is shown in the following example:
+
+```erb
+# app/views/products/show.html.erb
+<%= t('product_price', price: @product.price) %>
+```
+
+```yaml
+# config/locales/en.yml
+en:
+  product_price: "$%{price}"
+
+# config/locales/es.yml
+es:
+  product_price: "%{price} €"
+```
+
+All grammatical and punctuation decisions are made in the definition itself, so
+the abstraction can give a proper translation.
+
+NOTE: The `default` and `scope` keywords are reserved and can't be used as
+variable names. If used, an `I18n::ReservedInterpolationKey` exception is raised.
+If a translation expects an interpolation variable, but this has not been passed
+to `#translate`, an `I18n::MissingInterpolationArgument` exception is raised.
+
 ### Adding Date/Time Formats
 
 OK! Now let's add a timestamp to the view, so we can demo the **date/time localization** feature as well. To localize the time format you pass the Time object to `I18n.l` or (preferably) use Rails' `#l` helper. You can pick a format by passing the `:format` option - by default the `:default` format is used.
@@ -449,7 +502,10 @@ You can make use of this feature, e.g. when working with a large amount of stati
 
 ### Organization of Locale Files
 
-When you are using the default SimpleStore shipped with the i18n library, dictionaries are stored in plain-text files on the disc. Putting translations for all parts of your application in one file per locale could be hard to manage. You can store these files in a hierarchy which makes sense to you.
+When you are using the default SimpleStore shipped with the i18n library,
+dictionaries are stored in plain-text files on the disk. Putting translations
+for all parts of your application in one file per locale could be hard to
+manage. You can store these files in a hierarchy which makes sense to you.
 
 For example, your `config/locales` directory could look like this:
 
@@ -489,7 +545,9 @@ NOTE: The default locale loading mechanism in Rails does not load locale files i
 Overview of the I18n API Features
 ---------------------------------
 
-You should have good understanding of using the i18n library now, knowing all necessary aspects of internationalizing a basic Rails application. In the following chapters, we'll cover it's features in more depth.
+You should have a good understanding of using the i18n library now and know how
+to internationalize a basic Rails application. In the following chapters, we'll
+cover its features in more depth.
 
 These chapters will show examples using both the `I18n.translate` method as well as the [`translate` view helper method](http://api.rubyonrails.org/classes/ActionView/Helpers/TranslationHelper.html#method-i-translate) (noting the additional feature provide by the view helper method).
 
@@ -530,7 +588,7 @@ Thus the following calls are equivalent:
 
 ```ruby
 I18n.t 'activerecord.errors.messages.record_invalid'
-I18n.t 'errors.messages.record_invalid', scope: :active_record
+I18n.t 'errors.messages.record_invalid', scope: :activerecord
 I18n.t :record_invalid, scope: 'activerecord.errors.messages'
 I18n.t :record_invalid, scope: [:activerecord, :errors, :messages]
 ```
@@ -588,20 +646,26 @@ you can look up the `books.index.title` value **inside** `app/views/books/index.
 
 NOTE: Automatic translation scoping by partial is only available from the `translate` view helper method.
 
-### Interpolation
+"Lazy" lookup can also be used in controllers:
 
-In many cases you want to abstract your translations so that **variables can be interpolated into the translation**. For this reason the I18n API provides an interpolation feature.
+```yaml
+en:
+  books:
+    create:
+      success: Book created!
+```
 
-All options besides `:default` and `:scope` that are passed to `#translate` will be interpolated to the translation:
+This is useful for setting flash messages for instance:
 
 ```ruby
-I18n.backend.store_translations :en, thanks: 'Thanks %{name}!'
-I18n.translate :thanks, name: 'Jeremy'
-# => 'Thanks Jeremy!'
+class BooksController < ApplicationController
+  def create
+    # ...
+    redirect_to books_url, notice: t('.success')
+  end
+end
 ```
 
-If a translation uses `:default` or `:scope` as an interpolation variable, an `I18n::ReservedInterpolationKey` exception is raised. If a translation expects an interpolation variable, but this has not been passed to `#translate`, an `I18n::MissingInterpolationArgument` exception is raised.
-
 ### Pluralization
 
 In English there are only one singular and one plural form for a given string, e.g. "1 message" and "2 messages". Other languages ([Arabic](http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html#ar), [Japanese](http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html#ja), [Russian](http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html#ru) and many more) have different grammars that have additional or fewer [plural forms](http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html). Thus, the I18n API provides a flexible pluralization feature.
@@ -687,7 +751,7 @@ you can safely pass the username as set by the user:
 
 ```erb
 <%# This is safe, it is going to be escaped if needed. %>
-<%= t('welcome_html', username: @current_user.username %>
+<%= t('welcome_html', username: @current_user.username) %>
 ```
 
 Safe strings on the other hand are interpolated verbatim.
@@ -809,7 +873,7 @@ So, for example, instead of the default error message `"cannot be blank"` you co
 
 | validation   | with option               | message                   | interpolation |
 | ------------ | ------------------------- | ------------------------- | ------------- |
-| confirmation | -                         | :confirmation             | -             |
+| confirmation | -                         | :confirmation             | attribute     |
 | acceptance   | -                         | :accepted                 | -             |
 | presence     | -                         | :blank                    | -             |
 | absence      | -                         | :present                  | -             |
@@ -829,6 +893,7 @@ So, for example, instead of the default error message `"cannot be blank"` you co
 | numericality | :equal_to                 | :equal_to                 | count         |
 | numericality | :less_than                | :less_than                | count         |
 | numericality | :less_than_or_equal_to    | :less_than_or_equal_to    | count         |
+| numericality | :other_than               | :other_than               | count         |
 | numericality | :only_integer             | :not_an_integer           | -             |
 | numericality | :odd                      | :odd                      | -             |
 | numericality | :even                     | :even                     | -             |
@@ -1009,7 +1074,7 @@ In other contexts you might want to change this behavior, though. E.g. the defau
 module I18n
   class JustRaiseExceptionHandler < ExceptionHandler
     def call(exception, locale, key, options)
-      if exception.is_a?(MissingTranslation)
+      if exception.is_a?(MissingTranslationData)
         raise exception.to_exception
       else
         super
@@ -1026,7 +1091,7 @@ This would re-raise only the `MissingTranslationData` exception, passing all oth
 However, if you are using `I18n::Backend::Pluralization` this handler will also raise `I18n::MissingTranslationData: translation missing: en.i18n.plural.rule` exception that should normally be ignored to fall back to the default pluralization rule for English locale. To avoid this you may use additional check for translation key:
 
 ```ruby
-if exception.is_a?(MissingTranslation) && key.to_s != 'i18n.plural.rule'
+if exception.is_a?(MissingTranslationData) && key.to_s != 'i18n.plural.rule'
   raise exception.to_exception
 else
   super
@@ -1072,11 +1137,8 @@ Resources
 Authors
 -------
 
-* [Sven Fuchs](http://www.workingwithrails.com/person/9963-sven-fuchs) (initial author)
-* [Karel Minařík](http://www.workingwithrails.com/person/7476-karel-mina-k)
-
-If you found this guide useful, please consider recommending its authors on [workingwithrails](http://www.workingwithrails.com).
-
+* [Sven Fuchs](http://svenfuchs.com) (initial author)
+* [Karel Minařík](http://www.karmi.cz)
 
 Footnotes
 ---------
diff --git a/guides/source/initialization.md b/guides/source/initialization.md
index 8fbb234698..ebe1cb206a 100644
--- a/guides/source/initialization.md
+++ b/guides/source/initialization.md
@@ -34,7 +34,7 @@ Launch!
 Let's start to boot and initialize the app. A Rails application is usually
 started by running `rails console` or `rails server`.
 
-### `railties/bin/rails`
+### `railties/exe/rails`
 
 The `rails` in the command `rails server` is a ruby executable in your load
 path. This executable contains the following lines:
@@ -45,7 +45,7 @@ load Gem.bin_path('railties', 'rails', version)
 ```
 
 If you try out this command in a Rails console, you would see that this loads
-`railties/bin/rails`. A part of the file `railties/bin/rails.rb` has the
+`railties/exe/rails`. A part of the file `railties/exe/rails.rb` has the
 following code:
 
 ```ruby
@@ -53,11 +53,11 @@ require "rails/cli"
 ```
 
 The file `railties/lib/rails/cli` in turn calls
-`Rails::AppRailsLoader.exec_app_rails`.
+`Rails::AppLoader.exec_app`.
 
-### `railties/lib/rails/app_rails_loader.rb`
+### `railties/lib/rails/app_loader.rb`
 
-The primary goal of the function `exec_app_rails` is to execute your app's
+The primary goal of the function `exec_app` is to execute your app's
 `bin/rails`. If the current directory does not have a `bin/rails`, it will
 navigate upwards until it finds a `bin/rails` executable. Thus one can invoke a
 `rails` command from anywhere inside a rails application.
@@ -86,10 +86,9 @@ The `APP_PATH` constant will be used later in `rails/commands`. The `config/boot
 `config/boot.rb` contains:
 
 ```ruby
-# Set up gems listed in the Gemfile.
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
 
-require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
+require 'bundler/setup' # Set up gems listed in the Gemfile.
 ```
 
 In a standard Rails application, there's a `Gemfile` which declares all
@@ -106,6 +105,7 @@ A standard Rails application depends on several gems, specifically:
 * activemodel
 * activerecord
 * activesupport
+* activejob
 * arel
 * builder
 * bundler
@@ -163,7 +163,7 @@ throwing an error message. If the command is valid, a method of the same name
 is called.
 
 ```ruby
-COMMAND_WHITELIST = %(plugin generate destroy console server dbconsole application runner new version help)
+COMMAND_WHITELIST = %w(plugin generate destroy console server dbconsole application runner new version help)
 
 def run_command!(command)
   command = parse_command(command)
@@ -532,6 +532,7 @@ require "rails"
   action_controller
   action_view
   action_mailer
+  active_job
   rails/test_unit
   sprockets
 ).each do |framework|
@@ -555,9 +556,8 @@ I18n and Rails configuration are all being defined here.
 The rest of `config/application.rb` defines the configuration for the
 `Rails::Application` which will be used once the application is fully
 initialized. When `config/application.rb` has finished loading Rails and defined
-the application namespace, we go back to `config/environment.rb`,
-where the application is initialized. For example, if the application was called
-`Blog`, here we would find `Rails.application.initialize!`, which is
+the application namespace, we go back to `config/environment.rb`. Here, the
+application is initialized with `Rails.application.initialize!`, which is
 defined in `rails/application.rb`.
 
 ### `railties/lib/rails/application.rb`
diff --git a/guides/source/kindle/layout.html.erb b/guides/source/kindle/layout.html.erb
index f0a286210b..fd8746776b 100644
--- a/guides/source/kindle/layout.html.erb
+++ b/guides/source/kindle/layout.html.erb
@@ -14,12 +14,12 @@
 
   <% if content_for? :header_section %>
     <%= yield :header_section %>
-    <div class="pagebreak">
+    <div class="pagebreak"></div>
   <% end %>
 
   <% if content_for? :index_section %>
     <%= yield :index_section %>
-    <div class="pagebreak">
+    <div class="pagebreak"></div>
   <% end %>
 
   <%= yield.html_safe %>
diff --git a/guides/source/kindle/toc.ncx.erb b/guides/source/kindle/toc.ncx.erb
index 2c6d8e3bdf..5094fea4ca 100644
--- a/guides/source/kindle/toc.ncx.erb
+++ b/guides/source/kindle/toc.ncx.erb
@@ -32,12 +32,12 @@
       </navPoint>
       <navPoint class="article" id="credits" playOrder="3">
         <navLabel><text>Credits</text></navLabel>
-        <content src="credits.html">
+        <content src="credits.html"/>
       </navPoint>
       <navPoint class="article" id="copyright" playOrder="4">
         <navLabel><text>Copyright &amp; License</text></navLabel>
-        <content src="copyright.html">
-      </navPoint> 
+        <content src="copyright.html"/>
+      </navPoint>
     </navPoint>
 
     <% play_order = 4 %>
@@ -47,7 +47,7 @@
           <text><%= section['name'] %></text>
         </navLabel>
         <content src="<%=section['documents'].first['url'] %>"/>
-        
+
         <% section['documents'].each_with_index do |document, document_no| %>
           <navPoint class="article" id="_<%=section_no+1%>.<%=document_no+1%>" playOrder="<%=play_order +=1 %>">
             <navLabel>
diff --git a/guides/source/kindle/welcome.html.erb b/guides/source/kindle/welcome.html.erb
index 610a71570f..ef3397f58f 100644
--- a/guides/source/kindle/welcome.html.erb
+++ b/guides/source/kindle/welcome.html.erb
@@ -2,4 +2,6 @@
 
 <h3>Kindle Edition</h3>
 
-The Kindle Edition of the Rails Guides should be considered a work in progress. Feedback is really welcome. Please see the "Feedback" section at the end of each guide for instructions.
+<div>
+  The Kindle Edition of the Rails Guides should be considered a work in progress. Feedback is really welcome. Please see the "Feedback" section at the end of each guide for instructions.
+</div>
diff --git a/guides/source/layouts_and_rendering.md b/guides/source/layouts_and_rendering.md
index eb3c188d38..71cc030f6a 100644
--- a/guides/source/layouts_and_rendering.md
+++ b/guides/source/layouts_and_rendering.md
@@ -103,34 +103,6 @@ In most cases, the `ActionController::Base#render` method does the heavy lifting
 
 TIP: If you want to see the exact results of a call to `render` without needing to inspect it in a browser, you can call `render_to_string`. This method takes exactly the same options as `render`, but it returns a string instead of sending a response back to the browser.
 
-#### Rendering Nothing
-
-Perhaps the simplest thing you can do with `render` is to render nothing at all:
-
-```ruby
-render nothing: true
-```
-
-If you look at the response for this using cURL, you will see the following:
-
-```bash
-$ curl -i 127.0.0.1:3000/books
-HTTP/1.1 200 OK
-Connection: close
-Date: Sun, 24 Jan 2010 09:25:18 GMT
-Transfer-Encoding: chunked
-Content-Type: */*; charset=utf-8
-X-Runtime: 0.014297
-Set-Cookie: _blog_session=...snip...; path=/; HttpOnly
-Cache-Control: no-cache
-
-$
-```
-
-We see there is an empty response (no data after the `Cache-Control` line), but the request was successful because Rails has set the response to 200 OK. You can set the `:status` option on render to change this response. Rendering nothing can be useful for Ajax requests where all you want to send back to the browser is an acknowledgment that the request was completed.
-
-TIP: You should probably be using the `head` method, discussed later in this guide, instead of `render :nothing`. This provides additional flexibility and makes it explicit that you're only generating HTTP headers.
-
 #### Rendering an Action's View
 
 If you want to render the view that corresponds to a different template within the same controller, you can use `render` with the name of the view:
@@ -308,7 +280,7 @@ render body: "raw"
 ```
 
 TIP: This option should be used only if you don't care about the content type of
-the response. Using `:plain` or `:html` might be more appropriate in most of the
+the response. Using `:plain` or `:html` might be more appropriate most of the
 time.
 
 NOTE: Unless overridden, your response returned from this render option will be
@@ -316,12 +288,13 @@ NOTE: Unless overridden, your response returned from this render option will be
 
 #### Options for `render`
 
-Calls to the `render` method generally accept four options:
+Calls to the `render` method generally accept five options:
 
 * `:content_type`
 * `:layout`
 * `:location`
 * `:status`
+* `:formats`
 
 ##### The `:content_type` Option
 
@@ -387,7 +360,6 @@ Rails understands both numeric status codes and the corresponding symbols shown
 |                     | 303              | :see_other                       |
 |                     | 304              | :not_modified                    |
 |                     | 305              | :use_proxy                       |
-|                     | 306              | :reserved                        |
 |                     | 307              | :temporary_redirect              |
 |                     | 308              | :permanent_redirect              |
 | **Client Error**    | 400              | :bad_request                     |
@@ -403,10 +375,10 @@ Rails understands both numeric status codes and the corresponding symbols shown
 |                     | 410              | :gone                            |
 |                     | 411              | :length_required                 |
 |                     | 412              | :precondition_failed             |
-|                     | 413              | :request_entity_too_large        |
-|                     | 414              | :request_uri_too_long            |
+|                     | 413              | :payload_too_large               |
+|                     | 414              | :uri_too_long                    |
 |                     | 415              | :unsupported_media_type          |
-|                     | 416              | :requested_range_not_satisfiable |
+|                     | 416              | :range_not_satisfiable           |
 |                     | 417              | :expectation_failed              |
 |                     | 422              | :unprocessable_entity            |
 |                     | 423              | :locked                          |
@@ -427,9 +399,19 @@ Rails understands both numeric status codes and the corresponding symbols shown
 |                     | 510              | :not_extended                    |
 |                     | 511              | :network_authentication_required |
 
-NOTE:  If you try to render content along with a non-content status code 
+NOTE:  If you try to render content along with a non-content status code
 (100-199, 204, 205 or 304), it will be dropped from the response.
 
+##### The `:formats` Option
+
+Rails uses the format specified in the request (or `:html` by default). You can
+change this passing the `:formats` option with a symbol or an array:
+
+```ruby
+render formats: :xml
+render formats: [:json, :xml]
+```
+
 #### Finding Layouts
 
 To find the current layout, Rails first looks for a file in `app/views/layouts` with the same base name as the controller. For example, rendering actions from the `PhotosController` class will use `app/views/layouts/photos.html.erb` (or `app/views/layouts/photos.builder`). If there is no such controller-specific layout, Rails will use `app/views/layouts/application.html.erb` or `app/views/layouts/application.builder`. If there is no `.erb` layout, Rails will use a `.builder` layout if one exists. Rails also provides several ways to more precisely assign specific layouts to individual controllers and actions.
@@ -553,6 +535,42 @@ In this application:
 * `OldArticlesController#show` will use no layout at all
 * `OldArticlesController#index` will use the `old` layout
 
+##### Template Inheritance
+
+Similar to the Layout Inheritance logic, if a template or partial is not found in the conventional path, the controller will look for a template or partial to render in its inheritance chain. For example:
+
+```ruby
+# in app/controllers/application_controller
+class ApplicationController < ActionController::Base
+end
+
+# in app/controllers/admin_controller
+class AdminController < ApplicationController
+end
+
+# in app/controllers/admin/products_controller
+class Admin::ProductsController < AdminController
+  def index
+  end
+end
+```
+
+The lookup order for a `admin/products#index` action will be:
+
+* `app/views/admin/products/`
+* `app/views/admin/`
+* `app/views/application/`
+
+This makes `app/views/application/` a great place for your shared partials, which can then be rendered in your ERB as such:
+
+```erb
+<%# app/views/admin/products/index.html.erb %>
+<%= render @products || "empty_list" %>
+
+<%# app/views/application/_empty_list.html.erb %>
+There are no items in this list <em>yet</em>.
+```
+
 #### Avoiding Double Render Errors
 
 Sooner or later, most Rails developers will see the error message "Can only render or redirect once per action". While this is annoying, it's relatively easy to fix. Usually it happens because of a fundamental misunderstanding of the way that `render` works.
@@ -763,7 +781,7 @@ The `javascript_include_tag` helper returns an HTML `script` tag for each source
 
 If you are using Rails with the [Asset Pipeline](asset_pipeline.html) enabled, this helper will generate a link to `/assets/javascripts/` rather than `public/javascripts` which was used in earlier versions of Rails. This link is then served by the asset pipeline.
 
-A JavaScript file within a Rails application or Rails engine goes in one of three locations: `app/assets`, `lib/assets` or `vendor/assets`. These locations are explained in detail in the [Asset Organization section in the Asset Pipeline Guide](asset_pipeline.html#asset-organization)
+A JavaScript file within a Rails application or Rails engine goes in one of three locations: `app/assets`, `lib/assets` or `vendor/assets`. These locations are explained in detail in the [Asset Organization section in the Asset Pipeline Guide](asset_pipeline.html#asset-organization).
 
 You can specify a full path relative to the document root, or a URL, if you prefer. For example, to link to a JavaScript file that is inside a directory called `javascripts` inside of one of `app/assets`, `lib/assets` or `vendor/assets`, you would do this:
 
@@ -1028,9 +1046,14 @@ One way to use partials is to treat them as the equivalent of subroutines: as a
 <%= render "shared/footer" %>
 ```
 
-Here, the `_ad_banner.html.erb` and `_footer.html.erb` partials could contain content that is shared among many pages in your application. You don't need to see the details of these sections when you're concentrating on a particular page.
+Here, the `_ad_banner.html.erb` and `_footer.html.erb` partials could contain
+content that is shared by many pages in your application. You don't need to see
+the details of these sections when you're concentrating on a particular page.
 
-As you already could see from the previous sections of this guide, `yield` is a very powerful tool for cleaning up your layouts. Keep in mind that it's pure ruby, so you can use it almost everywhere. For example, we can use it to DRY form layout definition for several similar resources:
+As seen in the previous sections of this guide, `yield` is a very powerful tool
+for cleaning up your layouts. Keep in mind that it's pure Ruby, so you can use
+it almost everywhere. For example, we can use it to DRY up form layout
+definitions for several similar resources:
 
 * `users/index.html.erb`
 
@@ -1039,7 +1062,7 @@ As you already could see from the previous sections of this guide, `yield` is a
       <p>
         Name contains: <%= f.text_field :name_contains %>
       </p>
-    <%= end %>
+    <% end %>
     ```
 
 * `roles/index.html.erb`
@@ -1049,7 +1072,7 @@ As you already could see from the previous sections of this guide, `yield` is a
       <p>
         Title contains: <%= f.text_field :title_contains %>
       </p>
-    <%= end %>
+    <% end %>
     ```
 
 * `shared/_search_filters.html.erb`
@@ -1114,6 +1137,36 @@ You can also pass local variables into partials, making them even more powerful
 
 Although the same partial will be rendered into both views, Action View's submit helper will return "Create Zone" for the new action and "Update Zone" for the edit action.
 
+To pass a local variable to a partial in only specific cases use the `local_assigns`.
+
+* `index.html.erb`
+
+  ```erb
+  <%= render user.articles %>
+  ```
+
+* `show.html.erb`
+
+  ```erb
+  <%= render article, full: true %>
+  ```
+
+* `_articles.html.erb`
+
+  ```erb
+  <%= content_tag_for :article, article do |article| %>
+    <h2><%= article.title %></h2>
+
+    <% if local_assigns[:full] %>
+      <%= simple_format article.body %>
+    <% else %>
+      <%= truncate article.body %>
+    <% end %>
+  <% end %>
+  ```
+
+This way it is possible to use the partial without the need to declare all local variables.
+
 Every partial also has a local variable with the same name as the partial (minus the underscore). You can pass an object in to this local variable via the `:object` option:
 
 ```erb
diff --git a/guides/source/nested_model_forms.md b/guides/source/nested_model_forms.md
index 1937369776..121cf2b185 100644
--- a/guides/source/nested_model_forms.md
+++ b/guides/source/nested_model_forms.md
@@ -106,7 +106,7 @@ Consider the following typical RESTful controller which will prepare a new Perso
 class PeopleController < ApplicationController
   def new
     @person = Person.new
-    @person.built_address
+    @person.build_address
     2.times { @person.projects.build }
   end
 
diff --git a/guides/source/plugins.md b/guides/source/plugins.md
index 10738320ef..b94c26a1ae 100644
--- a/guides/source/plugins.md
+++ b/guides/source/plugins.md
@@ -265,7 +265,7 @@ module Yaffle
   end
 end
 
-ActiveRecord::Base.send :include, Yaffle::ActsAsYaffle
+ActiveRecord::Base.include(Yaffle::ActsAsYaffle)
 ```
 
 You can then return to the root directory (`cd ../..`) of your plugin and rerun the tests using `rake`.
@@ -308,7 +308,7 @@ module Yaffle
   end
 end
 
-ActiveRecord::Base.send :include, Yaffle::ActsAsYaffle
+ActiveRecord::Base.include(Yaffle::ActsAsYaffle)
 ```
 
 When you run `rake`, you should see the tests all pass:
@@ -382,7 +382,7 @@ module Yaffle
   end
 end
 
-ActiveRecord::Base.send :include, Yaffle::ActsAsYaffle
+ActiveRecord::Base.include(Yaffle::ActsAsYaffle)
 ```
 
 Run `rake` one final time and you should see:
@@ -443,4 +443,3 @@ $ bundle exec rake rdoc
 * [Developing a RubyGem using Bundler](https://github.com/radar/guides/blob/master/gem-development.md)
 * [Using .gemspecs as Intended](http://yehudakatz.com/2010/04/02/using-gemspecs-as-intended/)
 * [Gemspec Reference](http://guides.rubygems.org/specification-reference/)
-* [GemPlugins: A Brief Introduction to the Future of Rails Plugins](http://www.intridea.com/blog/2008/6/11/gemplugins-a-brief-introduction-to-the-future-of-rails-plugins)
diff --git a/guides/source/rails_application_templates.md b/guides/source/rails_application_templates.md
index b3e1874048..edd54826cf 100644
--- a/guides/source/rails_application_templates.md
+++ b/guides/source/rails_application_templates.md
@@ -78,7 +78,7 @@ gem_group :development, :test do
 end
 ```
 
-### add_source(source, options = {})
+### add_source(source, options={}, &block)
 
 Adds the given source to the generated application's `Gemfile`.
 
@@ -88,6 +88,14 @@ For example, if you need to source a gem from `"http://code.whytheluckystiff.net
 add_source "http://code.whytheluckystiff.net"
 ```
 
+If block is given, gem entries in block are wrapped into the source group.
+
+```ruby
+add_source "http://gems.github.com/" do
+  gem "rspec-rails"
+end
+```
+
 ### environment/application(data=nil, options={}, &block)
 
 Adds a line inside the `Application` class for `config/application.rb`.
@@ -215,7 +223,7 @@ CODE
 
 ### yes?(question) or no?(question)
 
-These methods let you ask questions from templates and decide the flow based on the user's answer. Let's say you want to freeze rails only if the user wants to:
+These methods let you ask questions from templates and decide the flow based on the user's answer. Let's say you want to Freeze Rails only if the user wants to:
 
 ```ruby
 rake("rails:freeze:gems") if yes?("Freeze rails gems?")
diff --git a/guides/source/rails_on_rack.md b/guides/source/rails_on_rack.md
index 21be74beba..87f869aff3 100644
--- a/guides/source/rails_on_rack.md
+++ b/guides/source/rails_on_rack.md
@@ -58,23 +58,6 @@ class Server < ::Rack::Server
 end
 ```
 
-Here's how it loads the middlewares:
-
-```ruby
-def middleware
-  middlewares = []
-  middlewares << [::Rack::ContentLength]
-  Hash.new(middlewares)
-end
-```
-
-`Rails::Rack::Debugger` is primarily useful only in the development environment. The following table explains the usage of the loaded middlewares:
-
-| Middleware              | Purpose                                                                           |
-| ----------------------- | --------------------------------------------------------------------------------- |
-| `Rails::Rack::Debugger` | Starts Debugger                                                                   |
-| `Rack::ContentLength`   | Counts the number of bytes in the response and set the HTTP Content-Length header |
-
 ### `rackup`
 
 To use `rackup` instead of Rails' `rails server`, you can put the following inside `config.ru` of your Rails application's root directory:
@@ -82,9 +65,6 @@ To use `rackup` instead of Rails' `rails server`, you can put the following insi
 ```ruby
 # Rails.root/config.ru
 require ::File.expand_path('../config/environment', __FILE__)
-
-use Rails::Rack::Debugger
-use Rack::ContentLength
 run Rails.application
 ```
 
@@ -141,7 +121,6 @@ use ActiveRecord::QueryCache
 use ActionDispatch::Cookies
 use ActionDispatch::Session::CookieStore
 use ActionDispatch::Flash
-use ActionDispatch::ParamsParser
 use Rack::Head
 use Rack::ConditionalGet
 use Rack::ETag
@@ -192,7 +171,7 @@ Add the following lines to your application configuration:
 
 ```ruby
 # config/application.rb
-config.middleware.delete "Rack::Lock"
+config.middleware.delete Rack::Lock
 ```
 
 And now if you inspect the middleware stack, you'll find that `Rack::Lock` is
@@ -212,16 +191,16 @@ If you want to remove session related middleware, do the following:
 
 ```ruby
 # config/application.rb
-config.middleware.delete "ActionDispatch::Cookies"
-config.middleware.delete "ActionDispatch::Session::CookieStore"
-config.middleware.delete "ActionDispatch::Flash"
+config.middleware.delete ActionDispatch::Cookies
+config.middleware.delete ActionDispatch::Session::CookieStore
+config.middleware.delete ActionDispatch::Flash
 ```
 
 And to remove browser related middleware,
 
 ```ruby
 # config/application.rb
-config.middleware.delete "Rack::MethodOverride"
+config.middleware.delete Rack::MethodOverride
 ```
 
 ### Internal Middleware Stack
@@ -254,7 +233,7 @@ Much of Action Controller's functionality is implemented as Middlewares. The fol
 
 **`ActionDispatch::RequestId`**
 
-* Makes a unique `X-Request-Id` header available to the response and enables the `ActionDispatch::Request#uuid` method.
+* Makes a unique `X-Request-Id` header available to the response and enables the `ActionDispatch::Request#request_id` method.
 
 **`Rails::Rack::Logger`**
 
@@ -304,10 +283,6 @@ Much of Action Controller's functionality is implemented as Middlewares. The fol
 
 * Sets up the flash keys. Only available if `config.action_controller.session_store` is set to a value.
 
-**`ActionDispatch::ParamsParser`**
-
-* Parses out parameters from the request into `params`.
-
 **`Rack::Head`**
 
 * Converts HEAD requests to `GET` requests and serves them as so.
@@ -329,8 +304,6 @@ Resources
 
 * [Official Rack Website](http://rack.github.io)
 * [Introducing Rack](http://chneukirchen.org/blog/archive/2007/02/introducing-rack.html)
-* [Ruby on Rack #1 - Hello Rack!](http://m.onkey.org/ruby-on-rack-1-hello-rack)
-* [Ruby on Rack #2 - The Builder](http://m.onkey.org/ruby-on-rack-2-the-builder)
 
 ### Understanding Middlewares
 
diff --git a/guides/source/routing.md b/guides/source/routing.md
index a689e131ff..245689932b 100644
--- a/guides/source/routing.md
+++ b/guides/source/routing.md
@@ -7,7 +7,7 @@ This guide covers the user-facing features of Rails routing.
 
 After reading this guide, you will know:
 
-* How to interpret the code in `routes.rb`.
+* How to interpret the code in `config/routes.rb`.
 * How to construct your own routes, using either the preferred resourceful style or the `match` method.
 * What parameters to expect an action to receive.
 * How to automatically create paths and URLs using route helpers.
@@ -79,11 +79,13 @@ it asks the router to map it to a controller action. If the first matching route
 resources :photos
 ```
 
-Rails would dispatch that request to the `destroy` method on the `photos` controller with `{ id: '17' }` in `params`.
+Rails would dispatch that request to the `destroy` action on the `photos` controller with `{ id: '17' }` in `params`.
 
 ### CRUD, Verbs, and Actions
 
-In Rails, a resourceful route provides a mapping between HTTP verbs and URLs to controller actions. By convention, each action also maps to particular CRUD operations in a database. A single entry in the routing file, such as:
+In Rails, a resourceful route provides a mapping between HTTP verbs and URLs to
+controller actions. By convention, each action also maps to a specific CRUD
+operation in a database. A single entry in the routing file, such as:
 
 ```ruby
 resources :photos
@@ -177,6 +179,8 @@ WARNING: A [long-standing bug](https://github.com/rails/rails/issues/1769) preve
 
 ```ruby
 form_for @geocoder, url: geocoder_path do |f|
+
+# snippet for brevity
 ```
 
 ### Controller Namespaces and Routing
@@ -229,7 +233,7 @@ or, for a single case:
 resources :articles, path: '/admin/articles'
 ```
 
-In each of these cases, the named routes remain the same as if you did not use `scope`. In the last case, the following paths map to `PostsController`:
+In each of these cases, the named routes remain the same as if you did not use `scope`. In the last case, the following paths map to `ArticlesController`:
 
 | HTTP Verb | Path                     | Controller#Action    | Named Helper           |
 | --------- | ------------------------ | -------------------- | ---------------------- |
@@ -613,6 +617,8 @@ get 'photos/:id', to: 'photos#show', defaults: { format: 'jpg' }
 
 Rails would match `photos/12` to the `show` action of `PhotosController`, and set `params[:format]` to `"jpg"`.
 
+NOTE: You cannot override defaults via query parameters - this is for security reasons. The only defaults that can be overridden are dynamic segments via substitution in the URL path.
+
 ### Naming Routes
 
 You can specify a name for any route using the `:as` option:
@@ -791,7 +797,11 @@ get '/stories/:name', to: redirect { |path_params, req| "/articles/#{path_params
 get '/stories', to: redirect { |path_params, req| "/articles/#{req.subdomain}" }
 ```
 
-Please note that this redirection is a 301 "Moved Permanently" redirect. Keep in mind that some web browsers or proxy servers will cache this type of redirect, making the old page inaccessible.
+Please note that default redirection is a 301 "Moved Permanently" redirect. Keep in mind that some web browsers or proxy servers will cache this type of redirect, making the old page inaccessible. You can use the `:status` option to change the response status:
+
+```ruby
+get '/stories/:name', to: redirect('/articles/%{name}', status: 302)
+```
 
 In all of these cases, if you don't provide the leading host (`http://www.example.com`), Rails will take those details from the current request.
 
@@ -807,6 +817,21 @@ As long as `Sprockets` responds to `call` and returns a `[status, headers, body]
 
 NOTE: For the curious, `'articles#index'` actually expands out to `ArticlesController.action(:index)`, which returns a valid Rack application.
 
+If you specify a Rack application as the endpoint for a matcher, remember that
+the route will be unchanged in the receiving application. With the following
+route your Rack application should expect the route to be '/admin':
+
+```ruby
+match '/admin', to: AdminApp, via: :all
+```
+
+If you would prefer to have your Rack application receive requests at the root
+path instead, use mount:
+
+```ruby
+mount AdminApp, at: '/admin'
+```
+
 ### Using `root`
 
 You can specify what Rails should route `'/'` to with the `root` method:
@@ -909,7 +934,7 @@ The `:as` option lets you override the normal naming for the named route helpers
 resources :photos, as: 'images'
 ```
 
-will recognize incoming paths beginning with `/photos` and route the requests to `PhotosController`, but use the value of the :as option to name the helpers.
+will recognize incoming paths beginning with `/photos` and route the requests to `PhotosController`, but use the value of the `:as` option to name the helpers.
 
 | HTTP Verb | Path             | Controller#Action | Named Helper         |
 | --------- | ---------------- | ----------------- | -------------------- |
@@ -1006,7 +1031,7 @@ TIP: If your application has many RESTful routes, using `:only` and `:except` to
 
 ### Translated Paths
 
-Using `scope`, we can alter path names generated by resources:
+Using `scope`, we can alter path names generated by `resources`:
 
 ```ruby
 scope(path_names: { new: 'neu', edit: 'bearbeiten' }) do
@@ -1070,6 +1095,20 @@ edit_videos GET  /videos/:identifier/edit(.:format) videos#edit
 Video.find_by(identifier: params[:identifier])
 ```
 
+You can override `ActiveRecord::Base#to_param` of a related model to construct
+a URL:
+
+```ruby
+class Video < ActiveRecord::Base
+  def to_param
+    identifier
+  end
+end
+
+video = Video.find_by(identifier: "Roman-Holiday")
+edit_videos_path(video) # => "/videos/Roman-Holiday"
+```
+
 Inspecting and Testing Routes
 -----------------------------
 
@@ -1079,7 +1118,7 @@ Rails offers facilities for inspecting and testing your routes.
 
 To get a complete list of the available routes in your application, visit `http://localhost:3000/rails/info/routes` in your browser while your server is running in the **development** environment. You can also execute the `rake routes` command in your terminal to produce the same output.
 
-Both methods will list all of your routes, in the same order that they appear in `routes.rb`. For each route, you'll see:
+Both methods will list all of your routes, in the same order that they appear in `config/routes.rb`. For each route, you'll see:
 
 * The route name (if any)
 * The HTTP verb used (if the route doesn't respond to all verbs)
diff --git a/guides/source/ruby_on_rails_guides_guidelines.md b/guides/source/ruby_on_rails_guides_guidelines.md
index 1323742488..50866350f8 100644
--- a/guides/source/ruby_on_rails_guides_guidelines.md
+++ b/guides/source/ruby_on_rails_guides_guidelines.md
@@ -64,7 +64,9 @@ The guides and the API should be coherent and consistent where appropriate. In p
 HTML Guides
 -----------
 
-Before generating the guides, make sure that you have the latest version of Bundler installed on your system. As of this writing, you must install Bundler 1.3.5 on your device.
+Before generating the guides, make sure that you have the latest version of
+Bundler installed on your system. As of this writing, you must install Bundler
+1.3.5 or later on your device.
 
 To install the latest version of Bundler, run `gem install bundler`.
 
@@ -82,6 +84,8 @@ or
 bundle exec rake guides:generate:html
 ```
 
+Resulting HTML files can be found in the `./output` directory.
+
 To process `my_guide.md` and nothing else use the `ONLY` environment variable:
 
 ```
diff --git a/guides/source/security.md b/guides/source/security.md
index e486edde31..fb9ee7b412 100644
--- a/guides/source/security.md
+++ b/guides/source/security.md
@@ -93,9 +93,16 @@ Rails 2 introduced a new default session storage, CookieStore. CookieStore saves
 
 * Cookies imply a strict size limit of 4kB. This is fine as you should not store large amounts of data in a session anyway, as described before. _Storing the current user's database id in a session is usually ok_.
 
-* The client can see everything you store in a session, because it is stored in clear-text (actually Base64-encoded, so not encrypted). So, of course, _you don't want to store any secrets here_. To prevent session hash tampering, a digest is calculated from the session with a server-side secret and inserted into the end of the cookie.
+* The client can see everything you store in a session, because it is stored in clear-text (actually Base64-encoded, so not encrypted). So, of course, _you don't want to store any secrets here_. To prevent session hash tampering, a digest is calculated from the session with a server-side secret (`secrets.secret_token`) and inserted into the end of the cookie.
 
-That means the security of this storage depends on this secret (and on the digest algorithm, which defaults to SHA1, for compatibility). So _don't use a trivial secret, i.e. a word from a dictionary, or one which is shorter than 30 characters_.
+However, since Rails 4, the default store is EncryptedCookieStore. With
+EncryptedCookieStore the session is encrypted before being stored in a cookie.
+This prevents the user from accessing and tampering the content of the cookie.
+Thus the session becomes a more secure place to store data. The encryption is
+done using a server-side secret key `secrets.secret_key_base` stored in
+`config/secrets.yml`.
+
+That means the security of this storage depends on this secret (and on the digest algorithm, which defaults to SHA1, for compatibility). So _don't use a trivial secret, i.e. a word from a dictionary, or one which is shorter than 30 characters, use `rake secret` instead_.
 
 `secrets.secret_key_base` is used for specifying a key which allows sessions for the application to be verified against a known secure key to prevent tampering. Applications get `secrets.secret_key_base` initialized to a random key present in `config/secrets.yml`, e.g.:
 
@@ -189,13 +196,12 @@ This attack method works by including malicious code or a link in a page that ac
 
 ![](images/csrf.png)
 
-In the [session chapter](#sessions) you have learned that most Rails applications use cookie-based sessions. Either they store the session id in the cookie and have a server-side session hash, or the entire session hash is on the client-side. In either case the browser will automatically send along the cookie on every request to a domain, if it can find a cookie for that domain. The controversial point is, that it will also send the cookie, if the request comes from a site of a different domain. Let's start with an example:
+In the [session chapter](#sessions) you have learned that most Rails applications use cookie-based sessions. Either they store the session id in the cookie and have a server-side session hash, or the entire session hash is on the client-side. In either case the browser will automatically send along the cookie on every request to a domain, if it can find a cookie for that domain. The controversial point is that if the request comes from a site of a different domain, it will also send the cookie. Let's start with an example:
 
-* Bob browses a message board and views a post from a hacker where there is a crafted HTML image element. The element references a command in Bob's project management application, rather than an image file.
-* `<img src="http://www.webapp.com/project/1/destroy">`
-* Bob's session at www.webapp.com is still alive, because he didn't log out a few minutes ago.
-* By viewing the post, the browser finds an image tag. It tries to load the suspected image from www.webapp.com. As explained before, it will also send along the cookie with the valid session id.
-* The web application at www.webapp.com verifies the user information in the corresponding session hash and destroys the project with the ID 1. It then returns a result page which is an unexpected result for the browser, so it will not display the image.
+* Bob browses a message board and views a post from a hacker where there is a crafted HTML image element. The element references a command in Bob's project management application, rather than an image file: `<img src="http://www.webapp.com/project/1/destroy">`
+* Bob's session at `www.webapp.com` is still alive, because he didn't log out a few minutes ago.
+* By viewing the post, the browser finds an image tag. It tries to load the suspected image from `www.webapp.com`. As explained before, it will also send along the cookie with the valid session id.
+* The web application at `www.webapp.com` verifies the user information in the corresponding session hash and destroys the project with the ID 1. It then returns a result page which is an unexpected result for the browser, so it will not display the image.
 * Bob doesn't notice the attack - but a few days later he finds out that project number one is gone.
 
 It is important to notice that the actual crafted image or link doesn't necessarily have to be situated in the web application's domain, it can be anywhere - in a forum, blog post or email.
@@ -218,9 +224,9 @@ The HTTP protocol basically provides two main types of requests - GET and POST (
 * The interaction _changes the state_ of the resource in a way that the user would perceive (e.g., a subscription to a service), or
 * The user is _held accountable for the results_ of the interaction.
 
-If your web application is RESTful, you might be used to additional HTTP verbs, such as PATCH, PUT or DELETE. Most of today's web browsers, however do not support them - only GET and POST. Rails uses a hidden `_method` field to handle this barrier.
+If your web application is RESTful, you might be used to additional HTTP verbs, such as PATCH, PUT or DELETE. Most of today's web browsers, however, do not support them - only GET and POST. Rails uses a hidden `_method` field to handle this barrier.
 
-_POST requests can be sent automatically, too_. Here is an example for a link which displays www.harmless.com as destination in the browser's status bar. In fact it dynamically creates a new form that sends a POST request.
+_POST requests can be sent automatically, too_. In this example, the link www.harmless.com is shown as the destination in the browser's status bar. But it has actually dynamically created a new form that sends a POST request.
 
 ```html
 <a href="http://www.harmless.com/" onclick="
@@ -239,7 +245,9 @@ Or the attacker places the code into the onmouseover event handler of an image:
 <img src="http://www.harmless.com/img" width="400" height="400" onmouseover="..." />
 ```
 
-There are many other possibilities, like using a `<script>` tag to make a cross-site request to a URL with a JSONP or JavaScript response. The response is executable code that the attacker can find a way to run, possibly extracting sensitive data. To protect against this data leakage, we disallow cross-site `<script>` tags. Only Ajax requests may have JavaScript responses since `XMLHttpRequest` is subject to the browser Same-Origin policy - meaning only your site can initiate the request.
+There are many other possibilities, like using a `<script>` tag to make a cross-site request to a URL with a JSONP or JavaScript response. The response is executable code that the attacker can find a way to run, possibly extracting sensitive data. To protect against this data leakage, we must disallow cross-site `<script>` tags. Ajax requests, however, obey the browser's same-origin policy (only your own site is allowed to initiate `XmlHttpRequest`) so we can safely allow them to return JavaScript responses.
+
+Note: We can't distinguish a `<script>` tag's origin—whether it's a tag on your own site or on some other malicious site—so we must block all `<script>` across the board, even if it's actually a safe same-origin script served from your own site. In these cases, explicitly skip CSRF protection on actions that serve JavaScript meant for a `<script>` tag.
 
 To protect against all other forged requests, we introduce a _required security token_ that our site knows but other sites don't know. We include the security token in requests and verify it on the server. This is a one-liner in your application controller, and is the default for newly created rails applications:
 
@@ -293,7 +301,7 @@ This will redirect the user to the main action if they tried to access a legacy
 http://www.example.com/site/legacy?param1=xy&param2=23&host=www.attacker.com
 ```
 
-If it is at the end of the URL it will hardly be noticed and redirects the user to the attacker.com host. A simple countermeasure would be to _include only the expected parameters in a legacy action_ (again a whitelist approach, as opposed to removing unexpected parameters). _And if you redirect to an URL, check it with a whitelist or a regular expression_.
+If it is at the end of the URL it will hardly be noticed and redirects the user to the attacker.com host. A simple countermeasure would be to _include only the expected parameters in a legacy action_ (again a whitelist approach, as opposed to removing unexpected parameters). _And if you redirect to a URL, check it with a whitelist or a regular expression_.
 
 #### Self-contained XSS
 
@@ -398,7 +406,7 @@ NOTE: _Almost every web application has to deal with authorization and authentic
 
 There are a number of authentication plug-ins for Rails available. Good ones, such as the popular [devise](https://github.com/plataformatec/devise) and [authlogic](https://github.com/binarylogic/authlogic), store only encrypted passwords, not plain-text passwords. In Rails 3.1 you can use the built-in `has_secure_password` method which has similar features.
 
-Every new user gets an activation code to activate their account when they get an e-mail with a link in it. After activating the account, the activation_code columns will be set to NULL in the database. If someone requested an URL like these, they would be logged in as the first activated user found in the database (and chances are that this is the administrator):
+Every new user gets an activation code to activate their account when they get an e-mail with a link in it. After activating the account, the activation_code columns will be set to NULL in the database. If someone requested a URL like these, they would be logged in as the first activated user found in the database (and chances are that this is the administrator):
 
 ```
 http://localhost:3006/user/activate
@@ -449,14 +457,16 @@ Depending on your web application, there may be more ways to hijack the user's a
 
 ### CAPTCHAs
 
-INFO: _A CAPTCHA is a challenge-response test to determine that the response is not generated by a computer. It is often used to protect comment forms from automatic spam bots by asking the user to type the letters of a distorted image. The idea of a negative CAPTCHA is not for a user to prove that they are human, but reveal that a robot is a robot._
+INFO: _A CAPTCHA is a challenge-response test to determine that the response is not generated by a computer. It is often used to protect registration forms from attackers and comment forms from automatic spam bots by asking the user to type the letters of a distorted image. This is the positive CAPTCHA, but there is also the negative CAPTCHA. The idea of a negative CAPTCHA is not for a user to prove that they are human, but reveal that a robot is a robot._
 
-But not only spam robots (bots) are a problem, but also automatic login bots. A popular CAPTCHA API is [reCAPTCHA](http://recaptcha.net/) which displays two distorted images of words from old books. It also adds an angled line, rather than a distorted background and high levels of warping on the text as earlier CAPTCHAs did, because the latter were broken. As a bonus, using reCAPTCHA helps to digitize old books. [ReCAPTCHA](https://github.com/ambethia/recaptcha/) is also a Rails plug-in with the same name as the API.
+A popular positive CAPTCHA API is [reCAPTCHA](http://recaptcha.net/) which displays two distorted images of words from old books. It also adds an angled line, rather than a distorted background and high levels of warping on the text as earlier CAPTCHAs did, because the latter were broken. As a bonus, using reCAPTCHA helps to digitize old books. [ReCAPTCHA](https://github.com/ambethia/recaptcha/) is also a Rails plug-in with the same name as the API.
 
 You will get two keys from the API, a public and a private key, which you have to put into your Rails environment. After that you can use the recaptcha_tags method in the view, and the verify_recaptcha method in the controller. Verify_recaptcha will return false if the validation fails.
-The problem with CAPTCHAs is, they are annoying. Additionally, some visually impaired users have found certain kinds of distorted CAPTCHAs difficult to read. The idea of negative CAPTCHAs is not to ask a user to proof that they are human, but reveal that a spam robot is a bot.
+The problem with CAPTCHAs is that they have a negative impact on the user experience. Additionally, some visually impaired users have found certain kinds of distorted CAPTCHAs difficult to read. Still, positive CAPTCHAs are one of the best methods to prevent all kinds of bots from submitting forms.
 
-Most bots are really dumb, they crawl the web and put their spam into every form's field they can find. Negative CAPTCHAs take advantage of that and include a "honeypot" field in the form which will be hidden from the human user by CSS or JavaScript.
+Most bots are really dumb. They crawl the web and put their spam into every form's field they can find. Negative CAPTCHAs take advantage of that and include a "honeypot" field in the form which will be hidden from the human user by CSS or JavaScript.
+
+Note that negative CAPTCHAs are only effective against dumb bots and won't suffice to protect critical applications from targeted bots. Still, the negative and positive CAPTCHAs can be combined to increase the performance, e.g.,  if the "honeypot" field is not empty (bot detected), you won't need to verify the positive CAPTCHA, which would require a HTTPS request to Google ReCaptcha before computing the response.
 
 Here are some ideas how to hide honeypot fields by JavaScript and/or CSS:
 
@@ -570,7 +580,7 @@ NOTE: _When sanitizing, protecting or verifying something, prefer whitelists ove
 
 A blacklist can be a list of bad e-mail addresses, non-public actions or bad HTML tags. This is opposed to a whitelist which lists the good e-mail addresses, public actions, good HTML tags and so on. Although sometimes it is not possible to create a whitelist (in a SPAM filter, for example), _prefer to use whitelist approaches_:
 
-* Use before_action only: [...] instead of except: [...]. This way you don't forget to turn it off for newly added actions.
+* Use before_action except: [...] instead of only: [...] for security-related actions. This way you don't forget to enable security checks for newly added actions.
 * Allow &lt;strong&gt; instead of removing &lt;script&gt; against Cross-Site Scripting (XSS). See below for details.
 * Don't try to correct user input by blacklists:
     * This will make the attack work: "&lt;sc&lt;script&gt;ript&gt;".gsub("&lt;script&gt;", "")
@@ -710,7 +720,7 @@ The log files on www.attacker.com will read like this:
 GET http://www.attacker.com/_app_session=836c1c25278e5b321d6bea4f19cb57e2
 ```
 
-You can mitigate these attacks (in the obvious way) by adding the [httpOnly](http://dev.rubyonrails.org/ticket/8895) flag to cookies, so that document.cookie may not be read by JavaScript. Http only cookies can be used from IE v6.SP1, Firefox v2.0.0.5 and Opera 9.5. Safari is still considering, it ignores the option. But other, older browsers (such as WebTV and IE 5.5 on Mac) can actually cause the page to fail to load. Be warned that cookies [will still be visible using Ajax](http://ha.ckers.org/blog/20070719/firefox-implements-httponly-and-is-vulnerable-to-xmlhttprequest/), though.
+You can mitigate these attacks (in the obvious way) by adding the **httpOnly** flag to cookies, so that document.cookie may not be read by JavaScript. Http only cookies can be used from IE v6.SP1, Firefox v2.0.0.5 and Opera 9.5. Safari is still considering, it ignores the option. But other, older browsers (such as WebTV and IE 5.5 on Mac) can actually cause the page to fail to load. Be warned that cookies [will still be visible using Ajax](https://www.owasp.org/index.php/HTTPOnly#Browsers_Supporting_HttpOnly), though.
 
 ##### Defacement
 
@@ -752,7 +762,7 @@ s = sanitize(user_input, tags: tags, attributes: %w(href title))
 
 This allows only the given tags and does a good job, even against all kinds of tricks and malformed tags.
 
-As a second step, _it is good practice to escape all output of the application_, especially when re-displaying user input, which hasn't been input-filtered (as in the search form example earlier on). _Use `escapeHTML()` (or its alias `h()`) method_ to replace the HTML input characters &amp;, &quot;, &lt;, &gt; by their uninterpreted representations in HTML (`&amp;`, `&quot;`, `&lt`;, and `&gt;`). However, it can easily happen that the programmer forgets to use it, so _it is recommended to use the SafeErb gem. SafeErb reminds you to escape strings from external sources.
+As a second step, _it is good practice to escape all output of the application_, especially when re-displaying user input, which hasn't been input-filtered (as in the search form example earlier on). _Use `escapeHTML()` (or its alias `h()`) method_ to replace the HTML input characters &amp;, &quot;, &lt;, and &gt; by their uninterpreted representations in HTML (`&amp;`, `&quot;`, `&lt;`, and `&gt;`). However, it can easily happen that the programmer forgets to use it, so _it is recommended to use the SafeErb gem. SafeErb reminds you to escape strings from external sources.
 
 ##### Obfuscation and Encoding Injection
 
@@ -783,15 +793,13 @@ Another proof-of-concept webmail worm is Nduja, a cross-domain worm for four Ita
 
 In December 2006, 34,000 actual user names and passwords were stolen in a [MySpace phishing attack](http://news.netcraft.com/archives/2006/10/27/myspace_accounts_compromised_by_phishers.html). The idea of the attack was to create a profile page named "login_home_index_html", so the URL looked very convincing. Specially-crafted HTML and CSS was used to hide the genuine MySpace content from the page and instead display its own login form.
 
-The MySpace Samy worm will be discussed in the CSS Injection section.
-
 ### CSS Injection
 
 INFO: _CSS Injection is actually JavaScript injection, because some browsers (IE, some versions of Safari and others) allow JavaScript in CSS. Think twice about allowing custom CSS in your web application._
 
-CSS Injection is explained best by a well-known worm, the [MySpace Samy worm](http://namb.la/popular/tech.html). This worm automatically sent a friend request to Samy (the attacker) simply by visiting his profile. Within several hours he had over 1 million friend requests, but it creates too much traffic on MySpace, so that the site goes offline. The following is a technical explanation of the worm.
+CSS Injection is explained best by the well-known [MySpace Samy worm](http://namb.la/popular/tech.html). This worm automatically sent a friend request to Samy (the attacker) simply by visiting his profile. Within several hours he had over 1 million friend requests, which created so much traffic that MySpace went offline. The following is a technical explanation of that worm.
 
-MySpace blocks many tags, however it allows CSS. So the worm's author put JavaScript into CSS like this:
+MySpace blocked many tags, but allowed CSS. So the worm's author put JavaScript into CSS like this:
 
 ```html
 <div style="background:url('javascript:alert(1)')">
@@ -815,7 +823,7 @@ The next problem was MySpace filtering the word "javascript", so the author used
 <div id="mycode" expr="alert('hah!')" style="background:url('java↵
script:eval(document.all.mycode.expr)')">
 ```
 
-Another problem for the worm's author were CSRF security tokens. Without them he couldn't send a friend request over POST. He got around it by sending a GET to the page right before adding a user and parsing the result for the CSRF token.
+Another problem for the worm's author was the [CSRF security tokens](#cross-site-request-forgery-csrf). Without them he couldn't send a friend request over POST. He got around it by sending a GET to the page right before adding a user and parsing the result for the CSRF token.
 
 In the end, he got a 4 KB worm, which he injected into his profile page.
 
@@ -923,7 +931,7 @@ HTTP/1.1 200 OK [Second New response created by attacker begins]
 Content-Type: text/html
 
 
-&lt;html&gt;&lt;font color=red&gt;hey&lt;/font&gt;&lt;/html&gt; [Arbitary malicious input is
+&lt;html&gt;&lt;font color=red&gt;hey&lt;/font&gt;&lt;/html&gt; [Arbitrary malicious input is
 Keep-Alive: timeout=15, max=100         shown as the redirected page]
 Connection: Keep-Alive
 Transfer-Encoding: chunked
@@ -969,7 +977,7 @@ request:
 | `{ "person": [null, null, ...] }` | `{ :person => [] }`     |
 | `{ "person": ["foo", null] }`     | `{ :person => ["foo"] }` |
 
-It is possible to return to old behaviour and disable `deep_munge` configuring
+It is possible to return to old behavior and disable `deep_munge` configuring
 your application if you are aware of the risk and know how to handle it:
 
 ```ruby
@@ -1006,24 +1014,41 @@ config.action_dispatch.default_headers.clear
 
 Here is a list of common headers:
 
-* X-Frame-Options
-_'SAMEORIGIN' in Rails by default_ - allow framing on same domain. Set it to 'DENY' to deny framing at all or 'ALLOWALL' if you want to allow framing for all website.
-* X-XSS-Protection
-_'1; mode=block' in Rails by default_ - use XSS Auditor and block page if XSS attack is detected. Set it to '0;' if you want to switch XSS Auditor off(useful if response contents scripts from request parameters)
-* X-Content-Type-Options
-_'nosniff' in Rails by default_ - stops the browser from guessing the MIME type of a file.
-* X-Content-Security-Policy
-[A powerful mechanism for controlling which sites certain content types can be loaded from](http://w3c.github.io/webappsec/specs/content-security-policy/csp-specification.dev.html)
-* Access-Control-Allow-Origin
-Used to control which sites are allowed to bypass same origin policies and send cross-origin requests.
-* Strict-Transport-Security
-[Used to control if the browser is allowed to only access a site over a secure connection](http://en.wikipedia.org/wiki/HTTP_Strict_Transport_Security)
+* **X-Frame-Options:** _'SAMEORIGIN' in Rails by default_ - allow framing on same domain. Set it to 'DENY' to deny framing at all or 'ALLOWALL' if you want to allow framing for all website.
+* **X-XSS-Protection:** _'1; mode=block' in Rails by default_ - use XSS Auditor and block page if XSS attack is detected. Set it to '0;' if you want to switch XSS Auditor off(useful if response contents scripts from request parameters)
+* **X-Content-Type-Options:** _'nosniff' in Rails by default_ - stops the browser from guessing the MIME type of a file.
+* **X-Content-Security-Policy:** [A powerful mechanism for controlling which sites certain content types can be loaded from](http://w3c.github.io/webappsec/specs/content-security-policy/csp-specification.dev.html)
+* **Access-Control-Allow-Origin:** Used to control which sites are allowed to bypass same origin policies and send cross-origin requests.
+* **Strict-Transport-Security:** [Used to control if the browser is allowed to only access a site over a secure connection](http://en.wikipedia.org/wiki/HTTP_Strict_Transport_Security)
 
 Environmental Security
 ----------------------
 
 It is beyond the scope of this guide to inform you on how to secure your application code and environments. However, please secure your database configuration, e.g. `config/database.yml`, and your server-side secret, e.g. stored in `config/secrets.yml`. You may want to further restrict access, using environment-specific versions of these files and any others that may contain sensitive information.
 
+### Custom secrets
+
+Rails generates a `config/secrets.yml`. By default, this file contains the
+application's `secret_key_base`, but it could also be used to store other
+secrets such as access keys for external APIs.
+
+The secrets added to this file are accessible via `Rails.application.secrets`.
+For example, with the following `config/secrets.yml`:
+
+    development:
+      secret_key_base: 3b7cd727ee24e8444053437c36cc66c3
+      some_api_key: SOMEKEY
+
+`Rails.application.secrets.some_api_key` returns `SOMEKEY` in the development
+environment.
+
+If you want an exception to be raised when some key is blank, use the bang
+version:
+
+```ruby
+Rails.application.secrets.some_api_key! # => raises KeyError
+```
+
 Additional Resources
 --------------------
 
@@ -1031,4 +1056,4 @@ The security landscape shifts and it is important to keep up to date, because mi
 
 * Subscribe to the Rails security [mailing list](http://groups.google.com/group/rubyonrails-security)
 * [Keep up to date on the other application layers](http://secunia.com/) (they have a weekly newsletter, too)
-* A [good security blog](http://ha.ckers.org/blog/) including the [Cross-Site scripting Cheat Sheet](http://ha.ckers.org/xss.html)
+* A [good security blog](https://www.owasp.org) including the [Cross-Site scripting Cheat Sheet](https://www.owasp.org/index.php/DOM_based_XSS_Prevention_Cheat_Sheet)
diff --git a/guides/source/testing.md b/guides/source/testing.md
index 94cfcf12b7..435de30acc 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -25,15 +25,7 @@ Rails tests can also simulate browser requests and thus you can test your applic
 Introduction to Testing
 -----------------------
 
-Testing support was woven into the Rails fabric from the beginning. It wasn't an "oh! let's bolt on support for running tests because they're new and cool" epiphany. Just about every Rails application interacts heavily with a database and, as a result, your tests will need a database to interact with as well. To write efficient tests, you'll need to understand how to set up this database and populate it with sample data.
-
-### The Test Environment
-
-By default, every Rails application has three environments: development, test, and production. The database for each one of them is configured in `config/database.yml`.
-
-A dedicated test database allows you to set up and interact with test data in isolation. This way your tests can mangle test data with confidence, without worrying about the data in the development or production databases.
-
-Also, each environment's configuration can be modified similarly. In this case, we can modify our test environment by changing the options found in `config/environments/test.rb`.
+Testing support was woven into the Rails fabric from the beginning. It wasn't an "oh! let's bolt on support for running tests because they're new and cool" epiphany.
 
 ### Rails Sets up for Testing from the Word Go
 
@@ -51,125 +43,18 @@ Fixtures are a way of organizing test data; they reside in the `fixtures` direct
 
 The `test_helper.rb` file holds the default configuration for your tests.
 
-### The Low-Down on Fixtures
-
-For good tests, you'll need to give some thought to setting up test data.
-In Rails, you can handle this by defining and customizing fixtures.
-You can find comprehensive documentation in the [Fixtures API documentation](http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html).
-
-#### What Are Fixtures?
-
-_Fixtures_ is a fancy word for sample data. Fixtures allow you to populate your testing database with predefined data before your tests run. Fixtures are database independent written in YAML. There is one file per model.
-
-You'll find fixtures under your `test/fixtures` directory. When you run `rails generate model` to create a new model fixture stubs will be automatically created and placed in this directory.
-
-#### YAML
-
-YAML-formatted fixtures are a human-friendly way to describe your sample data. These types of fixtures have the **.yml** file extension (as in `users.yml`).
-
-Here's a sample YAML fixture file:
 
-```yaml
-# lo & behold! I am a YAML comment!
-david:
-  name: David Heinemeier Hansson
-  birthday: 1979-10-15
-  profession: Systems development
-
-steve:
-  name: Steve Ross Kellock
-  birthday: 1974-09-27
-  profession: guy with keyboard
-```
-
-Each fixture is given a name followed by an indented list of colon-separated key/value pairs. Records are typically separated by a blank space. You can place comments in a fixture file by using the # character in the first column.
-
-If you are working with [associations](/association_basics.html), you can simply
-define a reference node between two different fixtures. Here's an example with
-a `belongs_to`/`has_many` association:
-
-```yaml
-# In fixtures/categories.yml
-about:
-  name: About
-
-# In fixtures/articles.yml
-one:
-  title: Welcome to Rails!
-  body: Hello world!
-  category: about
-```
-
-Notice the `category` key of the `one` article found in `fixtures/articles.yml` has a value of `about`. This tells Rails to load the category `about` found in `fixtures/categories.yml`.
-
-NOTE: For associations to reference one another by name, you cannot specify the `id:` attribute on the associated fixtures. Rails will auto assign a primary key to be consistent between runs. For more information on this association behavior please read the [Fixtures API documentation](http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html).
-
-#### ERB'in It Up
-
-ERB allows you to embed Ruby code within templates. The YAML fixture format is pre-processed with ERB when Rails loads fixtures. This allows you to use Ruby to help you generate some sample data. For example, the following code generates a thousand users:
-
-```erb
-<% 1000.times do |n| %>
-user_<%= n %>:
-  username: <%= "user#{n}" %>
-  email: <%= "user#{n}@example.com" %>
-<% end %>
-```
-
-#### Fixtures in Action
-
-Rails by default automatically loads all fixtures from the `test/fixtures` directory for your models and controllers test. Loading involves three steps:
-
-* Remove any existing data from the table corresponding to the fixture
-* Load the fixture data into the table
-* Dump the fixture data into a method in case you want to access it directly
-
-TIP: In order to remove existing data from the database, Rails tries to disable referential integrity triggers (like foreign keys and check constraints). If you are getting annoying permission errors on running tests, make sure the database user has privilege to disable these triggers in testing environment. (In PostgreSQL, only superusers can disable all triggers. Read more about PostgreSQL permissions [here](http://blog.endpoint.com/2012/10/postgres-system-triggers-error.html))
-
-#### Fixtures are Active Record objects
-
-Fixtures are instances of Active Record. As mentioned in point #3 above, you can access the object directly because it is automatically available as a method whose scope is local of the test case. For example:
-
-```ruby
-# this will return the User object for the fixture named david
-users(:david)
-
-# this will return the property for david called id
-users(:david).id
-
-# one can also access methods available on the User class
-email(david.girlfriend.email, david.location_tonight)
-```
-
-### Rake Tasks for Running your Tests
-
-Rails comes with a number of built-in rake tasks to help with testing. The
-table below lists the commands included in the default Rakefile when a Rails
-project is created.
-
-| Tasks                   | Description |
-| ----------------------- | ----------- |
-| `rake test`             | Runs all tests in the `test` directory. You can also run `rake` and Rails will run all tests by default |
-| `rake test:controllers` | Runs all the controller tests from `test/controllers` |
-| `rake test:functionals` | Runs all the functional tests from `test/controllers`, `test/mailers`, and `test/functional` |
-| `rake test:helpers`     | Runs all the helper tests from `test/helpers` |
-| `rake test:integration` | Runs all the integration tests from `test/integration` |
-| `rake test:jobs`        | Runs all the job tests from `test/jobs` |
-| `rake test:mailers`     | Runs all the mailer tests from `test/mailers` |
-| `rake test:models`      | Runs all the model tests from `test/models` |
-| `rake test:units`       | Runs all the unit tests from `test/models`, `test/helpers`, and `test/unit` |
-| `rake test:db`          | Runs all tests in the `test` directory and resets the db |
+### The Test Environment
 
-We will cover each of types Rails tests listed above in this guide.
+By default, every Rails application has three environments: development, test, and production.
 
-Unit Testing your Models
-------------------------
+Each environment's configuration can be modified similarly. In this case, we can modify our test environment by changing the options found in `config/environments/test.rb`.
 
-In Rails, unit tests are what you write to test your models.
+NOTE: Your tests are run under `RAILS_ENV=test`.
 
-For this guide we will be using the application we built in the [Getting Started with Rails](getting_started.html) guide.
+### Rails meets Minitest
 
-If you remember when you used the `rails generate scaffold` command from earlier. We created our first resource among other things it created a test stub in the `test/models` directory:
+If you remember when you used the `rails generate scaffold` command from the [Getting Started with Rails](getting_started.html) guide. We created our first resource among other things it created test stubs in the `test` directory:
 
 ```bash
 $ bin/rails generate scaffold article title:string body:text
@@ -244,47 +129,6 @@ An assertion is a line of code that evaluates an object (or expression) for expe
 
 Every test must contain at least one assertion, with no restriction as to how many assertions are allowed. Only when all the assertions are successful will the test pass.
 
-### Maintaining the test database schema
-
-In order to run your tests, your test database will need to have the current
-structure. The test helper checks whether your test database has any pending
-migrations. If so, it will try to load your `db/schema.rb` or `db/structure.sql`
-into the test database. If migrations are still pending, an error will be
-raised. Usually this indicates that your schema is not fully migrated. Running
-the migrations against the development database (`bin/rake db:migrate`) will
-bring the schema up to date.
-
-NOTE: If existing migrations required modifications, the test database needs to
-be rebuilt. This can be done by executing `bin/rake db:test:prepare`.
-
-### Running Tests
-
-Running a test is as simple as invoking the file containing the test cases through `rake test` command.
-
-```bash
-$ bin/rake test test/models/article_test.rb
-.
-
-Finished tests in 0.009262s, 107.9680 tests/s, 107.9680 assertions/s.
-
-1 tests, 1 assertions, 0 failures, 0 errors, 0 skips
-```
-
-You can also run a particular test method from the test case by running the test and providing the `test method name`.
-
-```bash
-$ bin/rake test test/models/article_test.rb test_the_truth
-.
-
-Finished tests in 0.009064s, 110.3266 tests/s, 110.3266 assertions/s.
-
-1 tests, 1 assertions, 0 failures, 0 errors, 0 skips
-```
-
-This will run all test methods from the test case.
-
-The `.` (dot) above indicates a passing test. When a test fails you see an `F`; when a test throws an error you see an `E` in its place. The last line of the output is the summary.
-
 #### Your first failing test
 
 To see how a test failure is reported, you can add a failing test to the `article_test.rb` test case.
@@ -296,10 +140,10 @@ test "should not save article without title" do
 end
 ```
 
-Let us run this newly added test.
+Let us run this newly added test (where `6` is the number of line where the test is defined).
 
 ```bash
-$ bin/rake test test/models/article_test.rb test_should_not_save_article_without_title
+$ bin/rails test test/models/article_test.rb:6
 F
 
 Finished tests in 0.044632s, 22.4054 tests/s, 22.4054 assertions/s.
@@ -339,7 +183,7 @@ end
 Now the test should pass. Let us verify by running the test again:
 
 ```bash
-$ bin/rake test test/models/article_test.rb test_should_not_save_article_without_title
+$ bin/rails test test/models/article_test.rb:6
 .
 
 Finished tests in 0.047721s, 20.9551 tests/s, 20.9551 assertions/s.
@@ -347,7 +191,11 @@ Finished tests in 0.047721s, 20.9551 tests/s, 20.9551 assertions/s.
 1 tests, 1 assertions, 0 failures, 0 errors, 0 skips
 ```
 
-Now, if you noticed, we first wrote a test which fails for a desired functionality, then we wrote some code which adds the functionality and finally we ensured that our test passes. This approach to software development is referred to as _Test-Driven Development_ (TDD).
+Now, if you noticed, we first wrote a test which fails for a desired
+functionality, then we wrote some code which adds the functionality and finally
+we ensured that our test passes. This approach to software development is
+referred to as
+[_Test-Driven Development_ (TDD)](http://c2.com/cgi/wiki?TestDrivenDevelopment).
 
 #### What an error looks like
 
@@ -364,7 +212,7 @@ end
 Now you can see even more output in the console from running the tests:
 
 ```bash
-$ bin/rake test test/models/article_test.rb test_should_report_error
+$ bin/rails test test/models/article_test.rb
 E
 
 Finished tests in 0.030974s, 32.2851 tests/s, 0.0000 assertions/s.
@@ -379,17 +227,20 @@ NameError: undefined local variable or method `some_undefined_variable' for #<Ar
 
 Notice the 'E' in the output. It denotes a test with error.
 
-NOTE: The execution of each test method stops as soon as any error or an assertion failure is encountered, and the test suite continues with the next method. All test methods are executed in alphabetical order.
+NOTE: The execution of each test method stops as soon as any error or an
+assertion failure is encountered, and the test suite continues with the next
+method. All test methods are executed in random order. The
+[`config.active_support.test_order` option](configuring.html#configuring-active-support)
+can be used to configure test order.
 
 When a test fails you are presented with the corresponding backtrace. By default
 Rails filters that backtrace and will only print lines relevant to your
 application. This eliminates the framework noise and helps to focus on your
 code. However there are situations when you want to see the full
-backtrace. simply set the `BACKTRACE` environment variable to enable this
-behavior:
+backtrace. Simply set the `-b` (or `--backtrace`) argument to enable this behavior:
 
 ```bash
-$ BACKTRACE=1 bin/rake test test/models/article_test.rb
+$ bin/rails test -b test/models/article_test.rb
 ```
 
 If we want this test to pass we can modify it to use `assert_raises` like so:
@@ -409,9 +260,49 @@ This test should now pass.
 
 By now you've caught a glimpse of some of the assertions that are available. Assertions are the worker bees of testing. They are the ones that actually perform the checks to ensure that things are going as planned.
 
-There are a bunch of different types of assertions you can use that come with [`Minitest`](https://github.com/seattlerb/minitest), the default testing library used by Rails.
-
-For a list of all available assertions please check the [Minitest API documentation](http://docs.seattlerb.org/minitest/), specifically [`Minitest::Assertions`](http://docs.seattlerb.org/minitest/Minitest/Assertions.html)
+Here's an extract of the assertions you can use with
+[`Minitest`](https://github.com/seattlerb/minitest), the default testing library
+used by Rails. The `[msg]` parameter is an optional string message you can
+specify to make your test failure messages clearer. It's not required.
+
+| Assertion                                                        | Purpose |
+| ---------------------------------------------------------------- | ------- |
+| `assert( test, [msg] )`                                          | Ensures that `test` is true.|
+| `assert_not( test, [msg] )`                                      | Ensures that `test` is false.|
+| `assert_equal( expected, actual, [msg] )`                        | Ensures that `expected == actual` is true.|
+| `assert_not_equal( expected, actual, [msg] )`                    | Ensures that `expected != actual` is true.|
+| `assert_same( expected, actual, [msg] )`                         | Ensures that `expected.equal?(actual)` is true.|
+| `assert_not_same( expected, actual, [msg] )`                     | Ensures that `expected.equal?(actual)` is false.|
+| `assert_nil( obj, [msg] )`                                       | Ensures that `obj.nil?` is true.|
+| `assert_not_nil( obj, [msg] )`                                   | Ensures that `obj.nil?` is false.|
+| `assert_empty( obj, [msg] )`                                     | Ensures that `obj` is `empty?`.|
+| `assert_not_empty( obj, [msg] )`                                 | Ensures that `obj` is not `empty?`.|
+| `assert_match( regexp, string, [msg] )`                          | Ensures that a string matches the regular expression.|
+| `assert_no_match( regexp, string, [msg] )`                       | Ensures that a string doesn't match the regular expression.|
+| `assert_includes( collection, obj, [msg] )`                      | Ensures that `obj` is in `collection`.|
+| `assert_not_includes( collection, obj, [msg] )`                  | Ensures that `obj` is not in `collection`.|
+| `assert_in_delta( expected, actual, [delta], [msg] )`            | Ensures that the numbers `expected` and `actual` are within `delta` of each other.|
+| `assert_not_in_delta( expected, actual, [delta], [msg] )`        | Ensures that the numbers `expected` and `actual` are not within `delta` of each other.|
+| `assert_throws( symbol, [msg] ) { block }`                       | Ensures that the given block throws the symbol.|
+| `assert_raises( exception1, exception2, ... ) { block }`         | Ensures that the given block raises one of the given exceptions.|
+| `assert_nothing_raised( exception1, exception2, ... ) { block }` | Ensures that the given block doesn't raise one of the given exceptions.|
+| `assert_instance_of( class, obj, [msg] )`                        | Ensures that `obj` is an instance of `class`.|
+| `assert_not_instance_of( class, obj, [msg] )`                    | Ensures that `obj` is not an instance of `class`.|
+| `assert_kind_of( class, obj, [msg] )`                            | Ensures that `obj` is an instance of `class` or is descending from it.|
+| `assert_not_kind_of( class, obj, [msg] )`                        | Ensures that `obj` is not an instance of `class` and is not descending from it.|
+| `assert_respond_to( obj, symbol, [msg] )`                        | Ensures that `obj` responds to `symbol`.|
+| `assert_not_respond_to( obj, symbol, [msg] )`                    | Ensures that `obj` does not respond to `symbol`.|
+| `assert_operator( obj1, operator, [obj2], [msg] )`               | Ensures that `obj1.operator(obj2)` is true.|
+| `assert_not_operator( obj1, operator, [obj2], [msg] )`           | Ensures that `obj1.operator(obj2)` is false.|
+| `assert_predicate ( obj, predicate, [msg] )`                     | Ensures that `obj.predicate` is true, e.g. `assert_predicate str, :empty?`|
+| `assert_not_predicate ( obj, predicate, [msg] )`                 | Ensures that `obj.predicate` is false, e.g. `assert_not_predicate str, :empty?`|
+| `assert_send( array, [msg] )`                                    | Ensures that executing the method listed in `array[1]` on the object in `array[0]` with the parameters of `array[2 and up]` is true. This one is weird eh?|
+| `flunk( [msg] )`                                                 | Ensures failure. This is useful to explicitly mark a test that isn't finished yet.|
+
+The above are a subset of assertions that minitest supports. For an exhaustive &
+more up-to-date list, please check
+[Minitest API documentation](http://docs.seattlerb.org/minitest/), specifically
+[`Minitest::Assertions`](http://docs.seattlerb.org/minitest/Minitest/Assertions.html).
 
 Because of the modular nature of the testing framework, it is possible to create your own assertions. In fact, that's exactly what Rails does. It includes some specialized assertions to make your life easier.
 
@@ -424,16 +315,15 @@ Rails adds some custom assertions of its own to the `minitest` framework:
 | Assertion                                                                         | Purpose |
 | --------------------------------------------------------------------------------- | ------- |
 | `assert_difference(expressions, difference = 1, message = nil) {...}`             | Test numeric difference between the return value of an expression as a result of what is evaluated in the yielded block.|
-| `assert_no_difference(expressions, message = nil, &amp;block)`                    | Asserts that the numeric result of evaluating an expression is not changed before and after invoking the passed in block.|
+| `assert_no_difference(expressions, message = nil, &block)`                        | Asserts that the numeric result of evaluating an expression is not changed before and after invoking the passed in block.|
 | `assert_recognizes(expected_options, path, extras={}, message=nil)`               | Asserts that the routing of the given path was handled correctly and that the parsed options (given in the expected_options hash) match path. Basically, it asserts that Rails recognizes the route given by expected_options.|
 | `assert_generates(expected_path, options, defaults={}, extras = {}, message=nil)` | Asserts that the provided options can be used to generate the provided path. This is the inverse of assert_recognizes. The extras parameter is used to tell the request the names and values of additional request parameters that would be in a query string. The message parameter allows you to specify a custom error message for assertion failures.|
 | `assert_response(type, message = nil)`                                            | Asserts that the response comes with a specific status code. You can specify `:success` to indicate 200-299, `:redirect` to indicate 300-399, `:missing` to indicate 404, or `:error` to match the 500-599 range. You can also pass an explicit status number or its symbolic equivalent. For more information, see [full list of status codes](http://rubydoc.info/github/rack/rack/master/Rack/Utils#HTTP_STATUS_CODES-constant) and how their [mapping](http://rubydoc.info/github/rack/rack/master/Rack/Utils#SYMBOL_TO_STATUS_CODE-constant) works.|
 | `assert_redirected_to(options = {}, message=nil)`                                 | Assert that the redirection options passed in match those of the redirect called in the latest action. This match can be partial, such that `assert_redirected_to(controller: "weblog")` will also match the redirection of `redirect_to(controller: "weblog", action: "show")` and so on. You can also pass named routes such as `assert_redirected_to root_path` and Active Record objects such as `assert_redirected_to @article`.|
-| `assert_template(expected = nil, message=nil)`                                    | Asserts that the request was rendered with the appropriate template file.|
 
 You'll see the usage of some of these assertions in the next chapter.
 
-### A Brief Note About Minitest
+### A Brief Note About Test Cases
 
 All the basic assertions such as `assert_equal` defined in `Minitest::Assertions` are also available in the classes we use in our own test cases. In fact, Rails provides the following classes for you to inherit from:
 
@@ -442,10 +332,307 @@ All the basic assertions such as `assert_equal` defined in `Minitest::Assertions
 * `ActionMailer::TestCase`
 * `ActionView::TestCase`
 * `ActionDispatch::IntegrationTest`
+* `ActiveJob::TestCase`
 
 Each of these classes include `Minitest::Assertions`, allowing us to use all of the basic assertions in our tests.
 
-NOTE: For more information on `Minitest`, refer to [Minitest](http://ruby-doc.org/stdlib-2.1.0/libdoc/minitest/rdoc/MiniTest.html)
+NOTE: For more information on `Minitest`, refer to [its
+documentation](http://docs.seattlerb.org/minitest).
+
+### The Rails Test Runner
+
+We can run all of our tests at once by using the `rails test` command.
+
+Or we can run a single test by passing the `rails test` command the filename containing the test cases.
+
+```bash
+$ bin/rails test test/models/article_test.rb
+.
+
+Finished tests in 0.009262s, 107.9680 tests/s, 107.9680 assertions/s.
+
+1 tests, 1 assertions, 0 failures, 0 errors, 0 skips
+```
+
+This will run all test methods from the test case.
+
+You can also run a particular test method from the test case by providing the
+`-n` or `--name` flag and the test's method name.
+
+```bash
+$ bin/rails test test/models/article_test.rb -n test_the_truth
+.
+
+Finished tests in 0.009064s, 110.3266 tests/s, 110.3266 assertions/s.
+
+1 tests, 1 assertions, 0 failures, 0 errors, 0 skips
+```
+
+You can also run a test at a specific line by providing the line number.
+
+```bash
+$ bin/rails test test/models/post_test.rb:44 # run specific test and line
+```
+
+You can also run an entire directory of tests by providing the path to the directory.
+
+```bash
+$ bin/rails test test/controllers # run all tests from specific directory
+```
+
+
+The Test Database
+-----------------
+
+Just about every Rails application interacts heavily with a database and, as a result, your tests will need a database to interact with as well. To write efficient tests, you'll need to understand how to set up this database and populate it with sample data.
+
+By default, every Rails application has three environments: development, test, and production. The database for each one of them is configured in `config/database.yml`.
+
+A dedicated test database allows you to set up and interact with test data in isolation. This way your tests can mangle test data with confidence, without worrying about the data in the development or production databases.
+
+
+### Maintaining the test database schema
+
+In order to run your tests, your test database will need to have the current
+structure. The test helper checks whether your test database has any pending
+migrations. If so, it will try to load your `db/schema.rb` or `db/structure.sql`
+into the test database. If migrations are still pending, an error will be
+raised. Usually this indicates that your schema is not fully migrated. Running
+the migrations against the development database (`bin/rake db:migrate`) will
+bring the schema up to date.
+
+NOTE: If existing migrations required modifications, the test database needs to
+be rebuilt. This can be done by executing `bin/rake db:test:prepare`.
+
+### The Low-Down on Fixtures
+
+For good tests, you'll need to give some thought to setting up test data.
+In Rails, you can handle this by defining and customizing fixtures.
+You can find comprehensive documentation in the [Fixtures API documentation](http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html).
+
+#### What Are Fixtures?
+
+_Fixtures_ is a fancy word for sample data. Fixtures allow you to populate your testing database with predefined data before your tests run. Fixtures are database independent and written in YAML. There is one file per model.
+
+You'll find fixtures under your `test/fixtures` directory. When you run `rails generate model` to create a new model, Rails automatically creates fixture stubs in this directory.
+
+#### YAML
+
+YAML-formatted fixtures are a human-friendly way to describe your sample data. These types of fixtures have the **.yml** file extension (as in `users.yml`).
+
+Here's a sample YAML fixture file:
+
+```yaml
+# lo & behold! I am a YAML comment!
+david:
+  name: David Heinemeier Hansson
+  birthday: 1979-10-15
+  profession: Systems development
+
+steve:
+  name: Steve Ross Kellock
+  birthday: 1974-09-27
+  profession: guy with keyboard
+```
+
+Each fixture is given a name followed by an indented list of colon-separated key/value pairs. Records are typically separated by a blank line. You can place comments in a fixture file by using the # character in the first column.
+
+If you are working with [associations](/association_basics.html), you can simply
+define a reference node between two different fixtures. Here's an example with
+a `belongs_to`/`has_many` association:
+
+```yaml
+# In fixtures/categories.yml
+about:
+  name: About
+
+# In fixtures/articles.yml
+one:
+  title: Welcome to Rails!
+  body: Hello world!
+  category: about
+```
+
+Notice the `category` key of the `one` article found in `fixtures/articles.yml` has a value of `about`. This tells Rails to load the category `about` found in `fixtures/categories.yml`.
+
+NOTE: For associations to reference one another by name, you cannot specify the `id:` attribute on the associated fixtures. Rails will auto assign a primary key to be consistent between runs. For more information on this association behavior please read the [Fixtures API documentation](http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html).
+
+#### ERB'in It Up
+
+ERB allows you to embed Ruby code within templates. The YAML fixture format is pre-processed with ERB when Rails loads fixtures. This allows you to use Ruby to help you generate some sample data. For example, the following code generates a thousand users:
+
+```erb
+<% 1000.times do |n| %>
+user_<%= n %>:
+  username: <%= "user#{n}" %>
+  email: <%= "user#{n}@example.com" %>
+<% end %>
+```
+
+#### Fixtures in Action
+
+Rails automatically loads all fixtures from the `test/fixtures` directory by
+default. Loading involves three steps:
+
+1. Remove any existing data from the table corresponding to the fixture
+2. Load the fixture data into the table
+3. Dump the fixture data into a method in case you want to access it directly
+
+TIP: In order to remove existing data from the database, Rails tries to disable referential integrity triggers (like foreign keys and check constraints). If you are getting annoying permission errors on running tests, make sure the database user has privilege to disable these triggers in testing environment. (In PostgreSQL, only superusers can disable all triggers. Read more about PostgreSQL permissions [here](http://blog.endpoint.com/2012/10/postgres-system-triggers-error.html)).
+
+#### Fixtures are Active Record objects
+
+Fixtures are instances of Active Record. As mentioned in point #3 above, you can access the object directly because it is automatically available as a method whose scope is local of the test case. For example:
+
+```ruby
+# this will return the User object for the fixture named david
+users(:david)
+
+# this will return the property for david called id
+users(:david).id
+
+# one can also access methods available on the User class
+email(david.partner.email, david.location_tonight)
+```
+
+To get multiple fixtures at once, you can pass in a list of fixture names. For example:
+
+```ruby
+# this will return an array containing the fixtures david and steve
+users(:david, :steve)
+```
+
+
+Model Testing
+-------------
+
+Model tests are used to test the various models of your application.
+
+Rails model tests are stored under the `test/models` directory. Rails provides
+a generator to create a model test skeleton for you.
+
+```bash
+$ bin/rails generate test_unit:model article title:string body:text
+create  test/models/article_test.rb
+create  test/fixtures/articles.yml
+```
+
+Model tests don't have their own superclass like `ActionMailer::TestCase` instead they inherit from `ActiveSupport::TestCase`.
+
+
+Integration Testing
+-------------------
+
+Integration tests are used to test how various parts of your application interact. They are generally used to test important work flows within your application.
+
+For creating Rails integration tests, we use the 'test/integration' directory for your application. Rails provides a generator to create an integration test skeleton for you.
+
+```bash
+$ bin/rails generate integration_test user_flows
+      exists  test/integration/
+      create  test/integration/user_flows_test.rb
+```
+
+Here's what a freshly-generated integration test looks like:
+
+```ruby
+require 'test_helper'
+
+class UserFlowsTest < ActionDispatch::IntegrationTest
+  # test "the truth" do
+  #   assert true
+  # end
+end
+```
+
+Inheriting from `ActionDispatch::IntegrationTest` comes with some advantages. This makes available some additional helpers to use in your integration tests.
+
+### Helpers Available for Integration Tests
+
+In addition to the standard testing helpers, inheriting `ActionDispatch::IntegrationTest` comes with some additional helpers available when writing integration tests. Let's briefly introduce you to the three categories of helpers you get to choose from.
+
+For dealing with the integration test runner, see [`ActionDispatch::Integration::Runner`](http://api.rubyonrails.org/classes/ActionDispatch/Integration/Runner.html).
+
+When performing requests, you will have [`ActionDispatch::Integration::RequestHelpers`](http://api.rubyonrails.org/classes/ActionDispatch/Integration/RequestHelpers.html) available for your use.
+
+If you'd like to modify the session, or state of your integration test you should look for [`ActionDispatch::Integration::Session`](http://api.rubyonrails.org/classes/ActionDispatch/Integration/Session.html) to help.
+
+### Implementing an integration test
+
+Let's add an integration test to our blog application. We'll start with a basic workflow of creating a new blog article, to verify that everything is working properly.
+
+We'll start by generating our integration test skeleton:
+
+```bash
+$ bin/rails generate integration_test blog_flow
+```
+
+It should have created a test file placeholder for us. With the output of the
+previous command you should see:
+
+```bash
+      invoke  test_unit
+      create    test/integration/blog_flow_test.rb
+```
+
+Now let's open that file and write our first assertion:
+
+```ruby
+require 'test_helper'
+
+class BlogFlowTest < ActionDispatch::IntegrationTest
+  test "can see the welcome page" do
+    get "/"
+    assert_select "h1", "Welcome#index"
+  end
+end
+```
+
+If you remember from earlier in the "Testing Views" section we covered `assert_select` to query the resulting HTML of a request.
+
+When visit our root path, we should see `welcome/index.html.erb` rendered for the view. So this assertion should pass.
+
+#### Creating articles integration
+
+How about testing our ability to create a new article in our blog and see the resulting article.
+
+```ruby
+test "can create an article" do
+  get "/articles/new"
+  assert_response :success
+
+  post "/articles",
+    params: { article: { title: "can create", body: "article successfully." } }
+  assert_response :redirect
+  follow_redirect!
+  assert_response :success
+  assert_select "p", "Title:\n  can create"
+end
+```
+
+Let's break this test down so we can understand it.
+
+We start by calling the `:new` action on our Articles controller. This response should be successful.
+
+After this we make a post request to the `:create` action of our Articles controller:
+
+```ruby
+post "/articles",
+  params: { article: { title: "can create", body: "article successfully." } }
+assert_response :redirect
+follow_redirect!
+```
+
+The two lines following the request are to handle the redirect we setup when creating a new article.
+
+NOTE: Don't forget to call `follow_redirect!` if you plan to make subsequent requests after a redirect is made.
+
+Finally we can assert that our response was successful and our new article is readable on the page.
+
+#### Taking it further
+
+We were able to successfully test a very small workflow for visiting our blog and creating a new article. If we wanted to take this further we could add tests for commenting, removing articles, or editing comments. Integration tests are a great place to experiment with all kinds of use-cases for our applications.
+
 
 Functional Tests for Your Controllers
 -------------------------------------
@@ -464,37 +651,54 @@ You should test for things such as:
 
 Now that we have used Rails scaffold generator for our `Article` resource, it has already created the controller code and tests. You can take look at the file `articles_controller_test.rb` in the `test/controllers` directory.
 
+The following command will generate a controller test case with a filled up
+test for each of the seven default actions.
+
+```bash
+$ bin/rails generate test_unit:scaffold article
+create test/controllers/articles_controller_test.rb
+```
+
 Let me take you through one such test, `test_should_get_index` from the file `articles_controller_test.rb`.
 
 ```ruby
+# articles_controller_test.rb
 class ArticlesControllerTest < ActionController::TestCase
   test "should get index" do
     get :index
     assert_response :success
-    assert_not_nil assigns(:articles)
+    assert_includes @response.body, 'Articles'
   end
 end
 ```
 
-In the `test_should_get_index` test, Rails simulates a request on the action called `index`, making sure the request was successful and also ensuring that it assigns a valid `articles` instance variable.
+In the `test_should_get_index` test, Rails simulates a request on the action called `index`, making sure the request was successful
+and also ensuring that the right response body has been generated.
 
 The `get` method kicks off the web request and populates the results into the response. It accepts 4 arguments:
 
-* The action of the controller you are requesting. This can be in the form of a string or a symbol.
-* An optional hash of request parameters to pass into the action (eg. query string parameters or article variables).
-* An optional hash of session variables to pass along with the request.
-* An optional hash of flash values.
+* The action of the controller you are requesting.
+  This can be in the form of a string or a symbol.
+
+* `params`: option with a hash of request parameters to pass into the action
+  (e.g. query string parameters or article variables).
+
+* `session`: option with a hash of session variables to pass along with the request.
+
+* `flash`: option with a hash of flash values.
+
+All the keyword arguments are optional.
 
 Example: Calling the `:show` action, passing an `id` of 12 as the `params` and setting a `user_id` of 5 in the session:
 
 ```ruby
-get(:show, {'id' => "12"}, {'user_id' => 5})
+get(:show, params: { id: 12 }, session: { user_id: 5 })
 ```
 
 Another example: Calling the `:view` action, passing an `id` of 12 as the `params`, this time with no session, but with a flash message.
 
 ```ruby
-get(:view, {'id' => '12'}, nil, {'message' => 'booya!'})
+get(:view, params: { id: 12 }, flash: { message: 'booya!' })
 ```
 
 NOTE: If you try running `test_should_create_article` test from `articles_controller_test.rb` it will fail on account of the newly added model level validation and rightly so.
@@ -504,10 +708,10 @@ Let us modify `test_should_create_article` test in `articles_controller_test.rb`
 ```ruby
 test "should create article" do
   assert_difference('Article.count') do
-    post :create, article: {title: 'Some title'}
+    post :create, params: { article: { title: 'Some title' } }
   end
 
-  assert_redirected_to article_path(assigns(:article))
+  assert_redirected_to article_path(Article.last)
 end
 ```
 
@@ -530,35 +734,32 @@ NOTE: Functional tests do not verify whether the specified request type is accep
 
 ### Testing XHR (AJAX) requests
 
-`xhr` accepts method (listed in the section above), action name and parameters:
+To test AJAX requests, you can specify the `xhr: true` option to `get`, `post`,
+`patch`, `put`, and `delete` methods:
 
 ```ruby
-test "ajax request responds with no layout" do
-  xhr :get, :show, id: articles(:first).id
+test "ajax request" do
+  get :show, params: { id: articles(:first).id }, xhr: true
 
-  assert_template :index
-  assert_template layout: nil
+  assert_equal 'hello world', @response.body
+  assert_equal "text/javascript", @response.content_type
 end
 ```
 
-### The Four Hashes of the Apocalypse
+### The Three Hashes of the Apocalypse
 
-After a request has been made and processed, you will have 4 Hash objects ready for use:
+After a request has been made and processed, you will have 3 Hash objects ready for use:
 
-* `assigns` - Any objects that are stored as instance variables in actions for use in views.
-* `cookies` - Any cookies that are set.
-* `flash` - Any objects living in the flash.
-* `session` - Any object living in session variables.
+* `cookies` - Any cookies that are set
+* `flash` - Any objects living in the flash
+* `session` - Any object living in session variables
 
-As is the case with normal Hash objects, you can access the values by referencing the keys by string. You can also reference them by symbol name, except for `assigns`. For example:
+As is the case with normal Hash objects, you can access the values by referencing the keys by string. You can also reference them by symbol name. For example:
 
 ```ruby
 flash["gordon"]               flash[:gordon]
 session["shmession"]          session[:shmession]
 cookies["are_good_for_u"]     cookies[:are_good_for_u]
-
-# Because you can't use assigns[:something] for historical reasons:
-assigns["something"]          assigns(:something)
 ```
 
 ### Instance Variables Available
@@ -586,49 +787,9 @@ get :index # simulate the request with custom header
 post :create # simulate the request with custom env variable
 ```
 
-### Testing Templates and Layouts
-
-Eventually, you may want to test whether a specific layout is rendered in the view of a response.
-
-#### Asserting Templates
-
-If you want to make sure that the response rendered the correct template and layout, you can use the `assert_template`
-method:
-
-```ruby
-test "index should render correct template and layout" do
-  get :index
-  assert_template :index
-  assert_template layout: "layouts/application"
-
-  # You can also pass a regular expression.
-  assert_template layout: /layouts\/application/
-end
-```
-
-NOTE: You cannot test for template and layout at the same time, with a single call to `assert_template`.
-
-WARNING: You must include the "layouts" directory name even if you save your layout file in this standard layout directory. Hence, `assert_template layout: "application"` will not work.
-
-#### Asserting Partials
-
-If your view renders any partial, when asserting for the layout, you can to assert for the partial at the same time.
-Otherwise, assertion will fail.
-
-Remember, we added the "_form" partial to our creating Articles view? Let's write an assertion for that in the `:new` action now:
-
-```ruby
-test "new should render correct layout" do
-  get :new
-  assert_template layout: "layouts/application", partial: "_form"
-end
-```
-
-This is the correct way to assert for when the view renders a partial with a given name. As identified by the `:partial` key passed to the `assert_template` call.
-
 ### Testing `flash` notices
 
-If you remember from earlier one of the Four Hashes of the Apocalypse was `flash`.
+If you remember from earlier one of the Three Hashes of the Apocalypse was `flash`.
 
 We want to add a `flash` message to our blog application whenever someone
 successfully creates a new Article.
@@ -638,10 +799,10 @@ Let's start by adding this assertion to our `test_should_create_article` test:
 ```ruby
 test "should create article" do
   assert_difference('Article.count') do
-    post :create, article: {title: 'Some title'}
+    post :create, params: { article: { title: 'Some title' } }
   end
 
-  assert_redirected_to article_path(assigns(:article))
+  assert_redirected_to article_path(Article.last)
   assert_equal 'Article was successfully created.', flash[:notice]
 end
 ```
@@ -649,7 +810,7 @@ end
 If we run our test now, we should see a failure:
 
 ```bash
-$ bin/rake test test/controllers/articles_controller_test.rb test_should_create_article
+$ bin/rails test test/controllers/articles_controller_test.rb test_should_create_article
 Run options: -n test_should_create_article --seed 32266
 
 # Running:
@@ -687,7 +848,7 @@ end
 Now if we run our tests, we should see it pass:
 
 ```bash
-$ bin/rake test test/controllers/articles_controller_test.rb test_should_create_article
+$ bin/rails test test/controllers/articles_controller_test.rb test_should_create_article
 Run options: -n test_should_create_article --seed 18981
 
 # Running:
@@ -708,7 +869,7 @@ Let's write a test for the `:show` action:
 ```ruby
 test "should show article" do
   article = articles(:one)
-  get :show, id: article.id
+  get :show, params: { id: article.id }
   assert_response :success
 end
 ```
@@ -721,7 +882,7 @@ How about deleting an existing Article?
 test "should destroy article" do
   article = articles(:one)
   assert_difference('Article.count', -1) do
-    delete :destroy, id: article.id
+    delete :destroy, params: { id: article.id }
   end
 
   assert_redirected_to articles_path
@@ -733,8 +894,8 @@ We can also add a test for updating an existing Article.
 ```ruby
 test "should update article" do
   article = articles(:one)
-  patch :update, id: article.id, article: {title: "updated"}
-  assert_redirected_to article_path(assigns(:article))
+  patch :update, params: { id: article.id, article: { title: "updated" } }
+  assert_redirected_to article_path(article)
 end
 ```
 
@@ -759,21 +920,21 @@ class ArticlesControllerTest < ActionController::TestCase
 
   test "should show article" do
     # Reuse the @article instance variable from setup
-    get :show, id: @article.id
+    get :show, params: { id: @article.id }
     assert_response :success
   end
 
   test "should destroy article" do
     assert_difference('Article.count', -1) do
-      delete :destroy, id: @article.id
+      delete :destroy, params: { id: @article.id }
     end
 
     assert_redirected_to articles_path
   end
 
   test "should update article" do
-    patch :update, id: @article.id, article: {title: "updated"}
-    assert_redirected_to article_path(assigns(:article))
+    patch :update, params: { id: @article.id, article: { title: "updated" } }
+    assert_redirected_to article_path(@article)
   end
 end
 ```
@@ -810,7 +971,6 @@ class ProfileControllerTest < ActionController::TestCase
 
     get :show
     assert_response :success
-    assert_equal users(:david), assigns(:user)
   end
 end
 ```
@@ -818,40 +978,14 @@ end
 Testing Routes
 --------------
 
-Like everything else in your Rails application, it is recommended that you test your routes. Below are example tests for the routes of default `show` and `create` action of `Articles` controller above and it should look like:
-
-```ruby
-class ArticleRoutesTest < ActionController::TestCase
-  test "should route to article" do
-    assert_routing '/articles/1', { controller: "articles", action: "show", id: "1" }
-  end
-
-  test "should route to create article" do
-    assert_routing({ method: 'post', path: '/articles' }, { controller: "articles", action: "create" })
-  end
-end
-```
-
-I've added this file here `test/controllers/articles_routes_test.rb` and if we run the test we should see:
-
-```bash
-$ bin/rake test test/controllers/articles_routes_test.rb
-
-# Running:
-
-..
-
-Finished in 0.069381s, 28.8263 runs/s, 86.4790 assertions/s.
-
-2 runs, 6 assertions, 0 failures, 0 errors, 0 skips
-```
+Like everything else in your Rails application, you can test your routes.
 
 For more information on routing assertions available in Rails, see the API documentation for [`ActionDispatch::Assertions::RoutingAssertions`](http://api.rubyonrails.org/classes/ActionDispatch/Assertions/RoutingAssertions.html).
 
 Testing Views
 -------------
 
-Testing the response to your request by asserting the presence of key HTML elements and their content is a common way to test the views of your application. The `assert_select` method allows you to query HTML elements of the response by using a simple yet powerful syntax.
+Testing the response to your request by asserting the presence of key HTML elements and their content is a common way to test the views of your application. Like route tests, view tests reside in `test/controllers/` or are part of controller tests. The `assert_select` method allows you to query HTML elements of the response by using a simple yet powerful syntax.
 
 There are two forms of `assert_select`:
 
@@ -912,7 +1046,7 @@ assert_select_email do
 end
 ```
 
-Testing helpers
+Testing Helpers
 ---------------
 
 In order to test helpers, all you need to do is check that the output of the
@@ -934,8 +1068,6 @@ have to use a mixin like this:
 
 ```ruby
 class UserHelperTest < ActionView::TestCase
-  include UserHelper
-
   test "should return the user name" do
     # ...
   end
@@ -945,118 +1077,6 @@ end
 Moreover, since the test class extends from `ActionView::TestCase`, you have
 access to Rails' helper methods such as `link_to` or `pluralize`.
 
-Integration Testing
--------------------
-
-Integration tests are used to test how various parts of your application interact. They are generally used to test important work flows within your application.
-
-For creating Rails integration tests, we use the 'test/integration' directory for your application. Rails provides a generator to create an integration test skeleton for you.
-
-```bash
-$ bin/rails generate integration_test user_flows
-      exists  test/integration/
-      create  test/integration/user_flows_test.rb
-```
-
-Here's what a freshly-generated integration test looks like:
-
-```ruby
-require 'test_helper'
-
-class UserFlowsTest < ActionDispatch::IntegrationTest
-  # test "the truth" do
-  #   assert true
-  # end
-end
-```
-
-Inheriting from `ActionDispatch::IntegrationTest` comes with some advantages. This makes available some additional helpers to use in your integration tests.
-
-### Helpers Available for Integration Tests
-
-In addition to the standard testing helpers, inheriting `ActionDispatch::IntegrationTest` comes with some additional helpers available when writing integration tests. Let's briefly introduce you to the three categories of helpers you get to choose from.
-
-For dealing with the integration test runner, see [`ActionDispatch::Integration::Runner`](http://api.rubyonrails.org/classes/ActionDispatch/Integration/Runner.html).
-
-When performing requests, you will have [`ActionDispatch::Integration::RequestHelpers`](http://api.rubyonrails.org/classes/ActionDispatch/Integration/RequestHelpers.html) available for your use.
-
-If you'd like to modify the session, or state of your integration test you should look for [`ActionDispatch::Integration::Session`](http://api.rubyonrails.org/classes/ActionDispatch/Integration/Session.html) to help.
-
-### Implementing an integration test
-
-Let's add an integration test to our blog application. We'll start with a basic workflow of creating a new blog article, to verify that everything is working properly.
-
-We'll start by generating our integration test skeleton:
-
-```bash
-$ bin/rails generate integration_test blog_flow
-```
-
-It should have created a test file placeholder for us, with the output of the previous command you should see:
-
-```bash
-      invoke  test_unit
-      create    test/integration/blog_flow_test.rb
-```
-
-Now let's open that file and write our first assertion:
-
-```ruby
-require 'test_helper'
-
-class BlogFlowTest < ActionDispatch::IntegrationTest
-  test "can see the welcome page" do
-    get "/"
-    assert_select "h1", "Welcome#index"
-  end
-end
-```
-
-If you remember from earlier in the "Testing Views" section we covered `assert_select` to query the resulting HTML of a request.
-
-When visit our root path, we should see `welcome/index.html.erb` rendered for the view. So this assertion should pass.
-
-#### Creating articles integration
-
-How about testing our ability to create a new article in our blog and see the resulting article.
-
-```ruby
-test "can create an article" do
-  get "/articles/new"
-  assert_response :success
-  assert_template "articles/new", partial: "articles/_form"
-
-  post "/articles", article: {title: "can create", body: "article successfully."}
-  assert_response :redirect
-  follow_redirect!
-  assert_response :success
-  assert_template "articles/show"
-  assert_select "p", "Title:\n  can create"
-end
-```
-
-Let's break this test down so we can understand it.
-
-We start by calling the `:new` action on our Articles controller. This response should be successful, and we can verify the correct template is rendered including the form partial.
-
-After this we make a post request to the `:create` action of our Articles controller:
-
-```ruby
-post "/articles", article: {title: "can create", body: "article successfully."}
-assert_response :redirect
-follow_redirect!
-```
-
-The two lines following the request are to handle the redirect we setup when creating a new article.
-
-NOTE: Don't forget to call `follow_redirect!` if you plan to make subsequent requests after a redirect is made.
-
-Finally we can assert that our response was successful, template was rendered, and our new article is readable on the page.
-
-#### Taking it further
-
-We were able to successfully test a very small workflow for visiting our blog and creating a new article. If we wanted to take this further we could add tests for commenting, removing articles, or editting comments. Integration tests are a great place to experiment with all kinds of use-cases for our applications.
-
 Testing Your Mailers
 --------------------
 
@@ -1064,7 +1084,7 @@ Testing mailer classes requires some specific tools to do a thorough job.
 
 ### Keeping the Postman in Check
 
-Your mailer classes - like every other part of your Rails application - should be tested to ensure that it is working as expected.
+Your mailer classes - like every other part of your Rails application - should be tested to ensure that they are working as expected.
 
 The goals of testing your mailer classes are to ensure that:
 
@@ -1095,10 +1115,13 @@ require 'test_helper'
 
 class UserMailerTest < ActionMailer::TestCase
   test "invite" do
+    # Create the email and store it for further assertions
+    email = UserMailer.create_invite('me@example.com',
+                                     'friend@example.com', Time.now)
+
     # Send the email, then test that it got queued
     assert_emails 1 do
-      email = UserMailer.create_invite('me@example.com',
-                                       'friend@example.com', Time.now).deliver_now
+      email.deliver_now
     end
 
     # Test the body of the sent email contains what we expect it to
@@ -1147,7 +1170,7 @@ require 'test_helper'
 class UserControllerTest < ActionController::TestCase
   test "invite friend" do
     assert_difference 'ActionMailer::Base.deliveries.size', +1 do
-      post :invite_friend, email: 'friend@example.com'
+      post :invite_friend, params: { email: 'friend@example.com' }
     end
     invite_email = ActionMailer::Base.deliveries.last
 
@@ -1201,7 +1224,7 @@ within a model:
 ```ruby
 require 'test_helper'
 
-class ProductTest < ActiveSupport::TestCase
+class ProductTest < ActiveJob::TestCase
   test 'billing job scheduling' do
     assert_enqueued_with(job: BillingJob) do
       product.charge(account)
@@ -1209,16 +1232,3 @@ class ProductTest < ActiveSupport::TestCase
   end
 end
 ```
-
-Other Testing Approaches
-------------------------
-
-The built-in `minitest` based testing is not the only way to test Rails applications. Rails developers have come up with a wide variety of other approaches and aids for testing, including:
-
-* [NullDB](http://avdi.org/projects/nulldb/), a way to speed up testing by avoiding database use.
-* [Factory Girl](https://github.com/thoughtbot/factory_girl/tree/master), a replacement for fixtures.
-* [Fixture Builder](https://github.com/rdy/fixture_builder), a tool that compiles Ruby factories into fixtures before a test run.
-* [MiniTest::Spec Rails](https://github.com/metaskills/minitest-spec-rails), use the MiniTest::Spec DSL within your rails tests.
-* [Shoulda](http://www.thoughtbot.com/projects/shoulda), an extension to `test/unit` with additional helpers, macros, and assertions.
-* [RSpec](http://relishapp.com/rspec), a behavior-driven development framework
-* [Capybara](http://jnicklas.github.com/capybara/), Acceptance test framework for web applications
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index d7fbe575c2..490bda3571 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -20,7 +20,7 @@ The best way to be sure that your application still works after upgrading is to
 
 Rails generally stays close to the latest released Ruby version when it's released:
 
-* Rails 5 requires Ruby 2.2 or newer.
+* Rails 5 requires Ruby 2.2.2 or newer.
 * Rails 4 prefers Ruby 2.0 and requires 1.9.3 or newer.
 * Rails 3.2.x is the last branch to support Ruby 1.8.7.
 * Rails 3 and above require Ruby 1.8.7 or higher. Support for all of the previous Ruby versions has been dropped officially. You should upgrade as early as possible.
@@ -55,26 +55,46 @@ Upgrading from Rails 4.2 to Rails 5.0
 
 ### Halting callback chains by returning `false`
 
-In Rails 4.2, when a 'before' callback returns `false` in ActiveRecord,
-ActiveModel and ActiveModel::Validations, then the entire callback chain
-is halted. In other words, successive 'before' callbacks are not executed,
-and neither is the action wrapped in callbacks.
+In Rails 4.2, when a 'before' callback returns `false` in Active Record
+and Active Model, then the entire callback chain is halted. In other words,
+successive 'before' callbacks are not executed, and neither is the action wrapped
+in callbacks.
 
-In Rails 5.0, returning `false` in a callback will not have this side effect
-of halting the callback chain. Instead, callback chains must be explicitly
-halted by calling `throw(:abort)`.
+In Rails 5.0, returning `false` in an Active Record or Active Model callback
+will not have this side effect of halting the callback chain. Instead, callback
+chains must be explicitly halted by calling `throw(:abort)`.
 
-When you upgrade from Rails 4.2 to Rails 5.0, returning `false` in a callback
-will still halt the callback chain, but you will receive a deprecation warning
-about this upcoming change.
+When you upgrade from Rails 4.2 to Rails 5.0, returning `false` in those kind of
+callbacks will still halt the callback chain, but you will receive a deprecation
+warning about this upcoming change.
 
 When you are ready, you can opt into the new behavior and remove the deprecation
 warning by adding the following configuration to your `config/application.rb`:
 
-    config.active_support.halt_callback_chains_on_return_false = false
+    ActiveSupport.halt_callback_chains_on_return_false = false
+
+Note that this option will not affect Active Support callbacks since they never
+halted the chain when any value was returned.
 
 See [#17227](https://github.com/rails/rails/pull/17227) for more details.
 
+### ActiveJob jobs now inherit from ApplicationJob by default
+
+In Rails 4.2 an ActiveJob inherits from `ActiveJob::Base`. In Rails 5.0 this
+behavior has changed to now inherit from `ApplicationJob`.
+
+When upgrading from Rails 4.2 to Rails 5.0 you need to create an
+`application_job.rb` file in `app/jobs/` and add the following content:
+
+```
+class ApplicationJob < ActiveJob::Base
+end
+```
+
+Then make sure that all your job classes inherit from it.
+
+See [#19034](https://github.com/rails/rails/pull/19034) for more details.
+
 Upgrading from Rails 4.1 to Rails 4.2
 -------------------------------------
 
@@ -276,16 +296,32 @@ class Notifier < ActionMailer::Base
 end
 ```
 
+### Foreign Key Support
+
+The migration DSL has been expanded to support foreign key definitions. If
+you've been using the Foreigner gem, you might want to consider removing it.
+Note that the foreign key support of Rails is a subset of Foreigner. This means
+that not every Foreigner definition can be fully replaced by its Rails
+migration DSL counterpart.
+
+The migration procedure is as follows:
+
+1. remove `gem "foreigner"` from the Gemfile.
+2. run `bundle install`.
+3. run `bin/rake db:schema:dump`.
+4. make sure that `db/schema.rb` contains every foreign key definition with
+the necessary options.
+
 Upgrading from Rails 4.0 to Rails 4.1
 -------------------------------------
 
 ### CSRF protection from remote `<script>` tags
 
-Or, "whaaat my tests are failing!!!?"
+Or, "whaaat my tests are failing!!!?" or "my `<script>` widget is busted!!"
 
 Cross-site request forgery (CSRF) protection now covers GET requests with
-JavaScript responses, too. This prevents a third-party site from referencing
-your JavaScript URL and attempting to run it to extract sensitive data.
+JavaScript responses, too. This prevents a third-party site from remotely
+referencing your JavaScript with a `<script>` tag to extract sensitive data.
 
 This means that your functional and integration tests that use
 
@@ -301,8 +337,9 @@ xhr :get, :index, format: :js
 
 to explicitly test an `XmlHttpRequest`.
 
-If you really mean to load JavaScript from remote `<script>` tags, skip CSRF
-protection on that action.
+Note: Your own `<script>` tags are treated as cross-origin and blocked by
+default, too. If you really mean to load JavaScript from `<script>` tags,
+you must now explicitly skip CSRF protection on those actions.
 
 ### Spring
 
@@ -427,7 +464,7 @@ If your application currently depend on MultiJSON directly, you have a few optio
 
 WARNING: Do not simply replace `MultiJson.dump` and `MultiJson.load` with
 `JSON.dump` and `JSON.load`. These JSON gem APIs are meant for serializing and
-deserializing arbitrary Ruby objects and are generally [unsafe](http://www.ruby-doc.org/stdlib-2.0.0/libdoc/json/rdoc/JSON.html#method-i-load).
+deserializing arbitrary Ruby objects and are generally [unsafe](http://www.ruby-doc.org/stdlib-2.2.2/libdoc/json/rdoc/JSON.html#method-i-load).
 
 #### JSON gem compatibility
 
@@ -534,7 +571,7 @@ module FixtureFileHelpers
     Digest::SHA2.hexdigest(File.read(Rails.root.join('test/fixtures', path)))
   end
 end
-ActiveRecord::FixtureSet.context_class.send :include, FixtureFileHelpers
+ActiveRecord::FixtureSet.context_class.include FixtureFileHelpers
 ```
 
 ### I18n enforcing available locales
@@ -850,6 +887,20 @@ this gem such as `whitelist_attributes` or `mass_assignment_sanitizer` options.
 
 * To re-enable the old finders, you can use the [activerecord-deprecated_finders gem](https://github.com/rails/activerecord-deprecated_finders).
 
+* Rails 4.0 has changed to default join table for `has_and_belongs_to_many` relations to strip the common prefix off the second table name. Any existing `has_and_belongs_to_many` relationship between models with a common prefix must be specified with the `join_table` option. For example:
+
+```ruby
+CatalogCategory < ActiveRecord::Base
+  has_and_belongs_to_many :catalog_products, join_table: 'catalog_categories_catalog_products'
+end
+
+CatalogProduct < ActiveRecord::Base
+  has_and_belongs_to_many :catalog_categories, join_table: 'catalog_categories_catalog_products'
+end
+```
+
+* Note that the prefix takes scopes into account as well, so relations between `Catalog::Category` and `Catalog::Product` or `Catalog::Category` and `CatalogProduct` need to be updated similarly.
+
 ### Active Resource
 
 Rails 4.0 extracted Active Resource to its own gem. If you still need the feature you can add the [Active Resource gem](https://github.com/rails/activeresource) in your Gemfile.
@@ -879,7 +930,7 @@ Rails 4.0 extracted Active Resource to its own gem. If you still need the featur
 
 Please note that you should wait to set `secret_key_base` until you have 100% of your userbase on Rails 4.x and are reasonably sure you will not need to rollback to Rails 3.x. This is because cookies signed based on the new `secret_key_base` in Rails 4.x are not backwards compatible with Rails 3.x. You are free to leave your existing `secret_token` in place, not set the new `secret_key_base`, and ignore the deprecation warnings until you are reasonably sure that your upgrade is otherwise complete.
 
-If you are relying on the ability for external applications or Javascript to be able to read your Rails app's signed session cookies (or signed cookies in general) you should not set `secret_key_base` until you have decoupled these concerns.
+If you are relying on the ability for external applications or JavaScript to be able to read your Rails app's signed session cookies (or signed cookies in general) you should not set `secret_key_base` until you have decoupled these concerns.
 
 * Rails 4.0 encrypts the contents of cookie-based sessions if `secret_key_base` has been set. Rails 3.x signed, but did not encrypt, the contents of cookie-based session. Signed cookies are "secure" in that they are verified to have been generated by your app and are tamper-proof. However, the contents can be viewed by end users, and encrypting the contents eliminates this caveat/concern without a significant performance penalty.
 
@@ -893,6 +944,8 @@ Please read [Pull Request #9978](https://github.com/rails/rails/pull/9978) for d
 
 * Rails 4.0 has removed the XML parameters parser. You will need to add the `actionpack-xml_parser` gem if you require this feature.
 
+* Rails 4.0 changes the default `layout` lookup set using symbols or procs that return nil. To get the "no layout" behavior, return false instead of nil. 
+
 * Rails 4.0 changes the default memcached client from `memcache-client` to `dalli`. To upgrade, simply add `gem 'dalli'` to your `Gemfile`.
 
 * Rails 4.0 deprecates the `dom_id` and `dom_class` methods in controllers (they are fine in views). You will need to include the `ActionView::RecordIdentifier` module in controllers requiring this feature.
diff --git a/guides/source/working_with_javascript_in_rails.md b/guides/source/working_with_javascript_in_rails.md
index 367abddcfa..1c42ff2914 100644
--- a/guides/source/working_with_javascript_in_rails.md
+++ b/guides/source/working_with_javascript_in_rails.md
@@ -258,7 +258,7 @@ this generates
 
 ```html
 <form action="/articles/1" class="button_to" data-remote="true" method="post">
-  <div><input type="submit" value="An article"></div>
+  <input type="submit" value="An article" />
 </form>
 ```
 
@@ -357,7 +357,7 @@ This gem uses Ajax to speed up page rendering in most applications.
 
 Turbolinks attaches a click handler to all `<a>` on the page. If your browser
 supports
-[PushState](https://developer.mozilla.org/en-US/docs/DOM/Manipulating_the_browser_history#The_pushState(\).C2.A0method),
+[PushState](https://developer.mozilla.org/en-US/docs/Web/Guide/API/DOM/Manipulating_the_browser_history#The_pushState%28%29_method),
 Turbolinks will make an Ajax request for the page, parse the response, and
 replace the entire `<body>` of the page with the `<body>` of the response. It
 will then use PushState to change the URL to the correct one, preserving
diff --git a/install.rb b/install.rb
deleted file mode 100644
index 96e4153165..0000000000
--- a/install.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-version = ARGV.pop
-
-if version.nil?
-  puts "Usage: ruby install.rb version"
-  exit(64)
-end
-
-%w( activesupport activemodel activerecord actionpack actionview actionmailer railties activejob ).each do |framework|
-  puts "Installing #{framework}..."
-  `cd #{framework} && gem build #{framework}.gemspec && gem install #{framework}-#{version}.gem --no-ri --no-rdoc && rm #{framework}-#{version}.gem`
-end
-
-puts "Installing rails..."
-`gem build rails.gemspec`
-`gem install rails-#{version}.gem --no-ri --no-rdoc `
-`rm rails-#{version}.gem`
diff --git a/rails.gemspec b/rails.gemspec
index b3143e6fe1..0286af0a57 100644
--- a/rails.gemspec
+++ b/rails.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'Full-stack web application framework.'
   s.description = 'Ruby on Rails is a full-stack web framework optimized for programmer happiness and sustainable productivity. It encourages beautiful code by favoring convention over configuration.'
 
-  s.required_ruby_version     = '>= 2.2.0'
+  s.required_ruby_version     = '>= 2.2.2'
   s.required_rubygems_version = '>= 1.8.11'
 
   s.license = 'MIT'
@@ -16,7 +16,7 @@ Gem::Specification.new do |s|
   s.email    = 'david@loudthinking.com'
   s.homepage = 'http://www.rubyonrails.org'
 
-  s.files = ['README.md'] + Dir['guides/**/*'] - Dir['guides/output/**/*']
+  s.files = ['README.md']
 
   s.add_dependency 'activesupport', version
   s.add_dependency 'actionpack',    version
@@ -28,5 +28,5 @@ Gem::Specification.new do |s|
   s.add_dependency 'railties',      version
 
   s.add_dependency 'bundler',         '>= 1.3.0', '< 2.0'
-  s.add_dependency 'sprockets-rails'
+  s.add_dependency 'sprockets-rails', '>= 2.0.0'
 end
diff --git a/railties/CHANGELOG.md b/railties/CHANGELOG.md
index 30b86db8bb..9337dd6407 100644
--- a/railties/CHANGELOG.md
+++ b/railties/CHANGELOG.md
@@ -1,8 +1,273 @@
-*   Add the `method_source` gem to the default Gemfile for apps
+*   Added javascript to update the URL on mailer previews with the currently
+    selected email format. Reloading the page now keeps you on your selected
+    format rather than going back to the default html version.
+
+    *James Kerr*
+
+*   Add fail fast to `bin/rails test`
+
+    Adding `--fail-fast` or `-f` when running tests will interrupt the run on
+    the first failure:
+
+    ```
+    # Running:
+
+    ................................................S......E
+
+    ArgumentError: Wups! Bet you didn't expect this!
+        test/models/bunny_test.rb:19:in `block in <class:BunnyTest>'
+
+    bin/rails test test/models/bunny_test.rb:18
+
+    ....................................F
+
+    This failed
+
+    bin/rails test test/models/bunny_test.rb:14
+
+    Interrupted. Exiting...
+
+
+    Finished in 0.051427s, 1808.3872 runs/s, 1769.4972 assertions/s.
+
+    ```
+
+    Note that any unexpected errors don't abort the run.
+
+    *Kasper Timm Hansen*
+
+*   Add inline output to `bin/rails test`
+
+    Any failures or errors (and skips if running in verbose mode) are output
+    during a test run:
+
+    ```
+    # Running:
+
+    .....S..........................................F
+
+    This failed
+
+    bin/rails test test/models/bunny_test.rb:14
+
+    .................................E
+
+    ArgumentError: Wups! Bet you didn't expect this!
+        test/models/bunny_test.rb:19:in `block in <class:BunnyTest>'
+
+    bin/rails test test/models/bunny_test.rb:18
+
+    ....................
+
+    Finished in 0.069708s, 1477.6019 runs/s, 1448.9106 assertions/s.
+    ```
+
+    Output can be deferred to after a run with the `--defer-output` option.
+
+    *Kasper Timm Hansen*
+
+*   Fix displaying mailer previews on non local requests when config
+    `action_mailer.show_previews` is set
+
+    *Wojciech Wnętrzak*
+
+*   `rails server` will now honour the `PORT` environment variable
+
+    *David Cornu*
+
+*   Plugins generated using `rails plugin new` are now generated with the
+    version number set to 0.1.0.
+
+    *Daniel Morris*
+
+*   `I18n.load_path` is now reloaded under development so there's no need to
+    restart the server to make new locale files available. Also, I18n will no
+    longer raise for deleted locale files.
+
+    *Kir Shatrov*
+
+*   Add `bin/update` script to update development environment automatically.
+
+    *Mehmet Emin İNAÇ*
+
+*   Fix STATS_DIRECTORIES already defined warning when running rake from within
+    the top level directory of an engine that has a test app.
+
+    Fixes #20510
+
+    *Ersin Akinci*
+
+*   Make enabling or disabling caching in development mode possible with
+    rake dev:cache.
+
+    Running rake dev:cache will create or remove tmp/caching-dev.txt. When this
+    file exists config.action_controller.perform_caching will be set to true in
+    config/environments/development.rb.
+
+    Additionally, a server can be started with either --dev-caching or
+    --no-dev-caching included to toggle caching on startup.
+
+    *Jussi Mertanen*, *Chuck Callebs*
+
+*   Add a `--api` option in order to generate plugins that can be added
+    inside an API application.
+
+    *Robin Dupret*
+
+*   Fix `NoMethodError` when generating a scaffold inside a full engine.
+
+    *Yuji Yaginuma*
+
+*   Adding support for passing a block to the `add_source` action of a custom generator
+
+    *Mike Dalton*, *Hirofumi Wakasugi*
+
+*   `assert_file` understands paths with special characters
+    (eg. `v0.1.4~alpha+nightly`).
+
+    *Diego Carrion*
+
+*   Remove ContentLength middleware from the defaults.  If you want it, just
+    add it as a middleware in your config.
+
+    *Egg McMuffin*
+
+*   Make it possible to customize the executable inside rerun snippets.
+
+    *Yves Senn*
+
+*   Add support for API only apps.
+    Middleware stack was slimmed down and it has only the needed
+    middleware for API apps & generators generates the right files,
+    folders and configurations.
+
+    *Santiago Pastorino & Jorge Bejar*
+
+*   Make generated scaffold functional tests work inside engines.
+
+    *Yuji Yaginuma*
+
+*   Generator a `.keep` file in the `tmp` folder by default as many scripts
+    assume the existence of this folder and most would fail if it is absent.
+
+    See #20299.
+
+    *Yoong Kang Lim*, *Sunny Juneja*
+
+*   `config.static_index` configures directory `index.html` filename
+
+    Set `config.static_index` to serve a static directory index file not named
+    `index`. E.g. to serve `main.html` instead of `index.html` for directory
+    requests, set `config.static_index` to `"main"`.
+
+    *Eliot Sykes*
+
+*   `bin/setup` uses built-in rake tasks (`log:clear`, `tmp:clear`).
+
+    *Mohnish Thallavajhula*
+
+*   Fix mailer previews with attachments by using the mail gem's own API to
+    locate the first part of the correct mime type.
+
+    Fixes #14435.
+
+    *Andrew White*
+
+*   Remove sqlite support from `rails dbconsole`.
+
+    *Andrew White*
+
+*   Rename `railties/bin` to `railties/exe` to match the new Bundler executables
+    convention.
+
+    *Islam Wazery*
+
+*   Print `bundle install` output in `rails new` as soon as it's available.
+
+    Running `rails new` will now print the output of `bundle install` as
+    it is available, instead of waiting until all gems finish installing.
+
+    *Max Holder*
+
+*   Respect `pluralize_table_names` when generating fixture file.
+
+    Fixes #19519.
+
+    *Yuji Yaginuma*
+
+*   Add a new-line to the end of route method generated code.
+
+    We need to add a `\n`, because we cannot have two routes
+    in the same line.
+
+    *arthurnn*
+
+*   Add `rake initializers`.
+
+    This task prints out all defined initializers in the order they are invoked
+    by Rails. This is helpful for debugging issues related to the initialization
+    process.
+
+    *Naoto Kaneko*
+
+*   Created rake restart task. Restarts your Rails app by touching the
+    `tmp/restart.txt`.
+
+    Fixes #18876.
+
+    *Hyonjee Joo*
+
+*   Add `config/initializers/active_record_belongs_to_required_by_default.rb`.
+
+    Newly generated Rails apps have a new initializer called
+    `active_record_belongs_to_required_by_default.rb` which sets the value of
+    the configuration option `config.active_record.belongs_to_required_by_default`
+    to `true` when ActiveRecord is not skipped.
+
+    As a result, new Rails apps require `belongs_to` association on model
+    to be valid.
+
+    This initializer is *not* added when running `rake rails:update`, so
+    old apps ported to Rails 5 will work without any change.
+
+    *Josef Šimánek*
+
+*   `delete` operations in configurations are run last in order to eliminate
+    'No such middleware' errors when `insert_before` or `insert_after` are added
+    after the `delete` operation for the middleware being deleted.
+
+    Fixes #16433.
+
+    *Guo Xiang Tan*
+
+*   Newly generated applications get a `README.md` in Markdown.
+
+    *Xavier Noria*
+
+*   Remove the documentation tasks `doc:app`, `doc:rails`, and `doc:guides`.
+
+    *Xavier Noria*
+
+*   Force generated routes to be inserted into `config/routes.rb`.
+
+    *Andrew White*
+
+*   Don't remove all line endings from `config/routes.rb` when revoking scaffold.
+
+    Fixes #15913.
+
+    *Andrew White*
+
+*   Rename `--skip-test-unit` option to `--skip-test` in app generator
+
+    *Melanie Gilman*
+
+*   Add the `method_source` gem to the default Gemfile for apps.
 
     *Sean Griffin*
 
-*   Drop old test locations from `rake stats`
+*   Drop old test locations from `rake stats`:
+
     - test/functional
     - test/unit
 
@@ -33,14 +298,15 @@
 
     *Andrew Kozlov*
 
-*   Add `config/initializers/callback_terminator.rb`
+*   Add `config/initializers/callback_terminator.rb`.
 
     Newly generated Rails apps have a new initializer called
     `callback_terminator.rb` which sets the value of the configuration option
-    `config.active_support.halt_callback_chains_on_return_false` to `false`.
+    `ActiveSupport.halt_callback_chains_on_return_false` to `false`.
 
-    As a result, new Rails apps do not halt callback chains when a callback
-    returns `false`; only when they are explicitly halted with `throw(:abort)`.
+    As a result, new Rails apps do not halt Active Record and Active Model
+    callback chains when a callback returns `false`; only when they are
+    explicitly halted with `throw(:abort)`.
 
     The terminator is *not* added when running `rake rails:update`, so returning
     `false` will still work on old apps ported to Rails 5, displaying a
diff --git a/railties/Rakefile b/railties/Rakefile
index 9a377ce4ee..cf130a5f14 100644
--- a/railties/Rakefile
+++ b/railties/Rakefile
@@ -1,5 +1,4 @@
 require 'rake/testtask'
-require 'rubygems/package_task'
 
 task :default => :test
 
@@ -27,24 +26,7 @@ end
 Rake::TestTask.new('test:regular') do |t|
   t.libs << 'test' << "#{File.dirname(__FILE__)}/../activesupport/lib"
   t.pattern = 'test/**/*_test.rb'
-  t.warning = true
+  t.warning = false
   t.verbose = true
   t.ruby_opts = ["--dev"] if defined?(JRUBY_VERSION)
 end
-
-# Generate GEM ----------------------------------------------------------------------------
-
-spec = eval(File.read('railties.gemspec'))
-
-Gem::PackageTask.new(spec) do |pkg|
-  pkg.gem_spec = spec
-end
-
-# Publishing -------------------------------------------------------
-
-desc "Release to rubygems"
-task :release => :package do
-  require 'rake/gemcutter'
-  Rake::Gemcutter::Tasks.new(spec).define
-  Rake::Task['gem:push'].invoke
-end
diff --git a/railties/bin/rails b/railties/exe/rails
index 82c17cabce..82c17cabce 100755
--- a/railties/bin/rails
+++ b/railties/exe/rails
diff --git a/railties/lib/rails.rb b/railties/lib/rails.rb
index b1f7c29b5a..fe789f3c2a 100644
--- a/railties/lib/rails.rb
+++ b/railties/lib/rails.rb
@@ -52,6 +52,11 @@ module Rails
       end
     end
 
+    # Returns a Pathname object of the current rails project,
+    # otherwise it returns nil if there is no project:
+    #
+    #   Rails.root
+    #     # => #<Pathname:/Users/someuser/some/path/project>
     def root
       application && application.config.root
     end
@@ -94,6 +99,11 @@ module Rails
       groups
     end
 
+    # Returns a Pathname object of the public folder of the current
+    # rails project, otherwise it returns nil if there is no project:
+    #
+    #   Rails.public_path
+    #     # => #<Pathname:/Users/someuser/some/path/project/public>
     def public_path
       application && Pathname.new(application.paths["public"].first)
     end
diff --git a/railties/lib/rails/api/task.rb b/railties/lib/rails/api/task.rb
index 4d49244807..a082932632 100644
--- a/railties/lib/rails/api/task.rb
+++ b/railties/lib/rails/api/task.rb
@@ -152,19 +152,5 @@ module Rails
         File.read('RAILS_VERSION').strip
       end
     end
-
-    class AppTask < Task
-      def component_root_dir(gem_name)
-        $:.grep(%r{#{gem_name}[\w.-]*/lib\z}).first[0..-5]
-      end
-
-      def api_dir
-        'doc/api'
-      end
-
-      def rails_version
-        Rails::VERSION::STRING
-      end
-    end
   end
 end
diff --git a/railties/lib/rails/app_rails_loader.rb b/railties/lib/rails/app_loader.rb
index 39d8007333..a9fe21824e 100644
--- a/railties/lib/rails/app_rails_loader.rb
+++ b/railties/lib/rails/app_loader.rb
@@ -1,7 +1,8 @@
 require 'pathname'
+require 'rails/version'
 
 module Rails
-  module AppRailsLoader
+  module AppLoader # :nodoc:
     extend self
 
     RUBY = Gem.ruby
@@ -9,7 +10,7 @@ module Rails
     BUNDLER_WARNING = <<EOS
 Looks like your app's ./bin/rails is a stub that was generated by Bundler.
 
-In Rails 4, your app's bin/ directory contains executables that are versioned
+In Rails #{Rails::VERSION::MAJOR}, your app's bin/ directory contains executables that are versioned
 like any other source code, rather than stubs that are generated on demand.
 
 Here's how to upgrade:
@@ -28,7 +29,7 @@ generate it and add it to source control:
 
 EOS
 
-    def exec_app_rails
+    def exec_app
       original_cwd = Dir.pwd
 
       loop do
diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index 8da73db821..e81ec62a1d 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -1,4 +1,5 @@
 require 'fileutils'
+require 'yaml'
 require 'active_support/core_ext/hash/keys'
 require 'active_support/core_ext/object/blank'
 require 'active_support/key_generator'
@@ -6,8 +7,7 @@ require 'active_support/message_verifier'
 require 'rails/engine'
 
 module Rails
-  # In Rails 3.0, a Rails::Application object was introduced which is nothing more than
-  # an Engine but with the responsibility of coordinating the whole boot process.
+  # An Engine with the responsibility of coordinating the whole boot process.
   #
   # == Initialization
   #
@@ -156,25 +156,20 @@ module Rails
       self
     end
 
-    # Implements call according to the Rack API. It simply
-    # dispatches the request to the underlying middleware stack.
-    def call(env)
-      env["ORIGINAL_FULLPATH"] = build_original_fullpath(env)
-      env["ORIGINAL_SCRIPT_NAME"] = env["SCRIPT_NAME"]
-      super(env)
-    end
-
     # Reload application routes regardless if they changed or not.
     def reload_routes!
       routes_reloader.reload!
     end
 
-    # Return the application's KeyGenerator
+    # Returns the application's KeyGenerator
     def key_generator
       # number of iterations selected based on consultation with the google security
       # team. Details at https://github.com/rails/rails/pull/6952#issuecomment-7661220
       @caching_key_generator ||=
         if secrets.secret_key_base
+          unless secrets.secret_key_base.kind_of?(String)
+            raise ArgumentError, "`secret_key_base` for #{Rails.env} environment must be a type of String, change this value in `config/secrets.yml`"
+          end
           key_generator = ActiveSupport::KeyGenerator.new(secrets.secret_key_base, iterations: 1000)
           ActiveSupport::CachingKeyGenerator.new(key_generator)
         else
@@ -227,7 +222,6 @@ module Rails
       yaml = Pathname.new("#{paths["config"].existent.first}/#{name}.yml")
 
       if yaml.exist?
-        require "yaml"
         require "erb"
         (YAML.load(ERB.new(yaml.read).result) || {})[Rails.env] || {}
       else
@@ -427,9 +421,9 @@ module Rails
     # Return an array of railties respecting the order they're loaded
     # and the order specified by the +railties_order+ config.
     #
-    # While when running initializers we need engines in reverse
-    # order here when copying migrations from railties we need then in the same
-    # order as given by +railties_order+
+    # While running initializers we need engines in reverse order here when
+    # copying migrations from railties ; we need them in the order given by
+    # +railties_order+.
     def migration_railties # :nodoc:
       ordered_railties.flatten - [self]
     end
@@ -504,27 +498,28 @@ module Rails
       default_stack.build_stack
     end
 
-    def build_original_fullpath(env) #:nodoc:
-      path_info    = env["PATH_INFO"]
-      query_string = env["QUERY_STRING"]
-      script_name  = env["SCRIPT_NAME"]
-
-      if query_string.present?
-        "#{script_name}#{path_info}?#{query_string}"
-      else
-        "#{script_name}#{path_info}"
-      end
-    end
-
     def validate_secret_key_config! #:nodoc:
       if secrets.secret_key_base.blank?
         ActiveSupport::Deprecation.warn "You didn't set `secret_key_base`. " +
           "Read the upgrade documentation to learn more about this new config option."
 
         if secrets.secret_token.blank?
-          raise "Missing `secret_token` and `secret_key_base` for '#{Rails.env}' environment, set these values in `config/secrets.yml`"
+          raise "Missing `secret_key_base` for '#{Rails.env}' environment, set this value in `config/secrets.yml`"
         end
       end
     end
+
+    private
+
+    def build_request(env)
+      req = super
+      env["ORIGINAL_FULLPATH"] = req.fullpath
+      env["ORIGINAL_SCRIPT_NAME"] = req.script_name
+      req
+    end
+
+    def build_middleware
+      config.app_middleware + super
+    end
   end
 end
diff --git a/railties/lib/rails/application/bootstrap.rb b/railties/lib/rails/application/bootstrap.rb
index 0f4d932749..9baf8aa742 100644
--- a/railties/lib/rails/application/bootstrap.rb
+++ b/railties/lib/rails/application/bootstrap.rb
@@ -63,7 +63,7 @@ INFO
           Rails.cache = ActiveSupport::Cache.lookup_store(config.cache_store)
 
           if Rails.cache.respond_to?(:middleware)
-            config.middleware.insert_before("Rack::Runtime", Rails.cache.middleware)
+            config.middleware.insert_before(::Rack::Runtime, Rails.cache.middleware)
           end
         end
       end
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 2821c8d757..ee9c87b5cf 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -6,17 +6,17 @@ require 'rails/source_annotation_extractor'
 module Rails
   class Application
     class Configuration < ::Rails::Engine::Configuration
-      attr_accessor :allow_concurrency, :asset_host, :assets, :autoflush_log,
+      attr_accessor :allow_concurrency, :asset_host, :autoflush_log,
                     :cache_classes, :cache_store, :consider_all_requests_local, :console,
                     :eager_load, :exceptions_app, :file_watcher, :filter_parameters,
                     :force_ssl, :helpers_paths, :logger, :log_formatter, :log_tags,
                     :railties_order, :relative_url_root, :secret_key_base, :secret_token,
-                    :serve_static_files, :ssl_options, :static_cache_control, :session_options,
-                    :time_zone, :reload_classes_only_on_change,
+                    :serve_static_files, :ssl_options, :static_index, :public_file_server,
+                    :session_options, :time_zone, :reload_classes_only_on_change,
                     :beginning_of_week, :filter_redirect, :x
 
       attr_writer :log_level
-      attr_reader :encoding
+      attr_reader :encoding, :api_only, :static_cache_control
 
       def initialize(*)
         super
@@ -27,7 +27,8 @@ module Rails
         @filter_redirect               = []
         @helpers_paths                 = []
         @serve_static_files            = true
-        @static_cache_control          = nil
+        @static_index                  = "index"
+        @public_file_server            = ActiveSupport::OrderedOptions.new
         @force_ssl                     = false
         @ssl_options                   = {}
         @session_store                 = :cookie_store
@@ -35,7 +36,6 @@ module Rails
         @time_zone                     = "UTC"
         @beginning_of_week             = :monday
         @log_level                     = nil
-        @middleware                    = app_middleware
         @generators                    = app_generators
         @cache_store                   = [ :file_store, "#{root}/tmp/cache/" ]
         @railties_order                = [:all]
@@ -48,22 +48,16 @@ module Rails
         @eager_load                    = nil
         @secret_token                  = nil
         @secret_key_base               = nil
+        @api_only                      = false
         @x                             = Custom.new
+      end
+
+      def static_cache_control=(value)
+        ActiveSupport::Deprecation.warn("static_cache_control is deprecated and will be removed in Rails 5.1. " \
+                                        "Please use `config.public_file_server.headers = {'Cache-Control' => #{value}} " \
+                                        "instead.")
 
-        @assets = ActiveSupport::OrderedOptions.new
-        @assets.enabled                  = true
-        @assets.paths                    = []
-        @assets.precompile               = [ Proc.new { |path, fn| fn =~ /app\/assets/ && !%w(.js .css).include?(File.extname(path)) },
-                                             /(?:\/|\\|\A)application\.(css|js)$/ ]
-        @assets.prefix                   = "/assets"
-        @assets.version                  = '1.0'
-        @assets.debug                    = false
-        @assets.compile                  = true
-        @assets.digest                   = false
-        @assets.cache_store              = [ :file_store, "#{root}/tmp/cache/assets/#{Rails.env}/" ]
-        @assets.js_compressor            = nil
-        @assets.css_compressor           = nil
-        @assets.logger                   = nil
+        @static_cache_control = value
       end
 
       def encoding=(value)
@@ -74,6 +68,11 @@ module Rails
         end
       end
 
+      def api_only=(value)
+        @api_only = value
+        generators.api_only = value
+      end
+
       def paths
         @paths ||= begin
           paths = super
diff --git a/railties/lib/rails/application/default_middleware_stack.rb b/railties/lib/rails/application/default_middleware_stack.rb
index 02eea82b0c..387d92db73 100644
--- a/railties/lib/rails/application/default_middleware_stack.rb
+++ b/railties/lib/rails/application/default_middleware_stack.rb
@@ -18,7 +18,10 @@ module Rails
           middleware.use ::Rack::Sendfile, config.action_dispatch.x_sendfile_header
 
           if config.serve_static_files
-            middleware.use ::ActionDispatch::Static, paths["public"].first, config.static_cache_control
+            headers = config.public_file_server.headers || {}
+            headers['Cache-Control'.freeze] = config.static_cache_control if config.static_cache_control
+
+            middleware.use ::ActionDispatch::Static, paths["public"].first, index: config.static_index, headers: headers
           end
 
           if rack_cache = load_rack_cache
@@ -26,9 +29,29 @@ module Rails
             middleware.use ::Rack::Cache, rack_cache
           end
 
-          middleware.use ::Rack::Lock unless allow_concurrency?
+          if config.allow_concurrency == false
+            # User has explicitly opted out of concurrent request
+            # handling: presumably their code is not threadsafe
+
+            middleware.use ::Rack::Lock
+
+          elsif config.allow_concurrency == :unsafe
+            # Do nothing, even if we know this is dangerous. This is the
+            # historical behaviour for true.
+
+          else
+            # Default concurrency setting: enabled, but safe
+
+            unless config.cache_classes && config.eager_load
+              # Without cache_classes + eager_load, the load interlock
+              # is required for proper operation
+
+              middleware.use ::ActionDispatch::LoadInterlock
+            end
+          end
+
           middleware.use ::Rack::Runtime
-          middleware.use ::Rack::MethodOverride
+          middleware.use ::Rack::MethodOverride unless config.api_only
           middleware.use ::ActionDispatch::RequestId
 
           # Must come after Rack::MethodOverride to properly log overridden methods
@@ -42,9 +65,9 @@ module Rails
           end
 
           middleware.use ::ActionDispatch::Callbacks
-          middleware.use ::ActionDispatch::Cookies
+          middleware.use ::ActionDispatch::Cookies unless config.api_only
 
-          if config.session_store
+          if !config.api_only && config.session_store
             if config.force_ssl && !config.session_options.key?(:secure)
               config.session_options[:secure] = true
             end
@@ -52,7 +75,6 @@ module Rails
             middleware.use ::ActionDispatch::Flash
           end
 
-          middleware.use ::ActionDispatch::ParamsParser
           middleware.use ::Rack::Head
           middleware.use ::Rack::ConditionalGet
           middleware.use ::Rack::ETag, "no-cache"
@@ -65,14 +87,6 @@ module Rails
           config.reload_classes_only_on_change != true || app.reloaders.map(&:updated?).any?
         end
 
-        def allow_concurrency?
-          if config.allow_concurrency.nil?
-            config.cache_classes && config.eager_load
-          else
-            config.allow_concurrency
-          end
-        end
-
         def load_rack_cache
           rack_cache = config.action_dispatch.rack_cache
           return unless rack_cache
diff --git a/railties/lib/rails/application/finisher.rb b/railties/lib/rails/application/finisher.rb
index 7a1bb1e25c..404e3c3e23 100644
--- a/railties/lib/rails/application/finisher.rb
+++ b/railties/lib/rails/application/finisher.rb
@@ -86,8 +86,10 @@ module Rails
       # added in the hook are taken into account.
       initializer :set_clear_dependencies_hook, group: :all do
         callback = lambda do
-          ActiveSupport::DescendantsTracker.clear
-          ActiveSupport::Dependencies.clear
+          ActiveSupport::Dependencies.interlock.attempt_unloading do
+            ActiveSupport::DescendantsTracker.clear
+            ActiveSupport::Dependencies.clear
+          end
         end
 
         if config.reload_classes_only_on_change
@@ -108,6 +110,13 @@ module Rails
           ActionDispatch::Reloader.to_cleanup(&callback)
         end
       end
+
+      # Disable dependency loading during request cycle
+      initializer :disable_dependency_loading do
+        if config.eager_load && config.cache_classes
+          ActiveSupport::Dependencies.unhook!
+        end
+      end
     end
   end
 end
diff --git a/railties/lib/rails/application_controller.rb b/railties/lib/rails/application_controller.rb
index 9a29ec21cf..618a09a5b3 100644
--- a/railties/lib/rails/application_controller.rb
+++ b/railties/lib/rails/application_controller.rb
@@ -6,7 +6,7 @@ class Rails::ApplicationController < ActionController::Base # :nodoc:
 
   def require_local!
     unless local_request?
-      render text: '<p>For security purposes, this information is only available to local requests.</p>', status: :forbidden
+      render html: '<p>For security purposes, this information is only available to local requests.</p>'.html_safe, status: :forbidden
     end
   end
 
diff --git a/railties/lib/rails/cli.rb b/railties/lib/rails/cli.rb
index dd70c272c6..a8794bc0de 100644
--- a/railties/lib/rails/cli.rb
+++ b/railties/lib/rails/cli.rb
@@ -1,8 +1,8 @@
-require 'rails/app_rails_loader'
+require 'rails/app_loader'
 
 # If we are inside a Rails application this method performs an exec and thus
 # the rest of this script is not run.
-Rails::AppRailsLoader.exec_app_rails
+Rails::AppLoader.exec_app
 
 require 'rails/ruby_version_check'
 Signal.trap("INT") { puts; exit(1) }
diff --git a/railties/lib/rails/code_statistics.rb b/railties/lib/rails/code_statistics.rb
index 0bdf63943f..fd352dc9b7 100644
--- a/railties/lib/rails/code_statistics.rb
+++ b/railties/lib/rails/code_statistics.rb
@@ -41,11 +41,9 @@ class CodeStatistics #:nodoc:
 
         if File.directory?(path) && (/^\./ !~ file_name)
           stats.add(calculate_directory_statistics(path, pattern))
+        elsif file_name =~ pattern
+          stats.add_by_file_path(path)
         end
-
-        next unless file_name =~ pattern
-
-        stats.add_by_file_path(path)
       end
 
       stats
@@ -71,12 +69,12 @@ class CodeStatistics #:nodoc:
 
     def print_header
       print_splitter
-      puts "| Name                 | Lines |   LOC | Classes | Methods | M/C | LOC/M |"
+      puts "| Name                 |  Lines |   LOC  | Classes | Methods | M/C | LOC/M |"
       print_splitter
     end
 
     def print_splitter
-      puts "+----------------------+-------+-------+---------+---------+-----+-------+"
+      puts "+----------------------+--------+--------+---------+---------+-----+-------+"
     end
 
     def print_line(name, statistics)
@@ -84,8 +82,8 @@ class CodeStatistics #:nodoc:
       loc_over_m = (statistics.code_lines / statistics.methods) - 2 rescue loc_over_m = 0
 
       puts "| #{name.ljust(20)} " \
-           "| #{statistics.lines.to_s.rjust(5)} " \
-           "| #{statistics.code_lines.to_s.rjust(5)} " \
+           "| #{statistics.lines.to_s.rjust(6)} " \
+           "| #{statistics.code_lines.to_s.rjust(6)} " \
            "| #{statistics.classes.to_s.rjust(7)} " \
            "| #{statistics.methods.to_s.rjust(7)} " \
            "| #{m_over_c.to_s.rjust(3)} " \
diff --git a/railties/lib/rails/commands.rb b/railties/lib/rails/commands.rb
index f32bf772a5..12bd73db24 100644
--- a/railties/lib/rails/commands.rb
+++ b/railties/lib/rails/commands.rb
@@ -6,7 +6,8 @@ aliases = {
   "c"  => "console",
   "s"  => "server",
   "db" => "dbconsole",
-  "r"  => "runner"
+  "r"  => "runner",
+  "t"  => "test",
 }
 
 command = ARGV.shift
diff --git a/railties/lib/rails/commands/commands_tasks.rb b/railties/lib/rails/commands/commands_tasks.rb
index 8bae08e44e..685d55eea8 100644
--- a/railties/lib/rails/commands/commands_tasks.rb
+++ b/railties/lib/rails/commands/commands_tasks.rb
@@ -14,6 +14,7 @@ The most common rails commands are:
  generate    Generate new code (short-cut alias: "g")
  console     Start the Rails console (short-cut alias: "c")
  server      Start the Rails server (short-cut alias: "s")
+ test        Run tests (short-cut alias: "t")
  dbconsole   Start a console for the database specified in config/database.yml
              (short-cut alias: "db")
  new         Create a new Rails application. "rails new my_app" creates a
@@ -27,7 +28,7 @@ In addition to those, there are:
 All commands can be run with -h (or --help) for more information.
 EOT
 
-    COMMAND_WHITELIST = %w(plugin generate destroy console server dbconsole runner new version help)
+    COMMAND_WHITELIST = %w(plugin generate destroy console server dbconsole runner new version help test)
 
     def initialize(argv)
       @argv = argv
@@ -81,6 +82,10 @@ EOT
       end
     end
 
+    def test
+      require_command!("test")
+    end
+
     def dbconsole
       require_command!("dbconsole")
       Rails::DBConsole.start
@@ -146,6 +151,17 @@ EOT
         puts HELP_MESSAGE
       end
 
+      # Output an error message stating that the attempted command is not a valid rails command.
+      # Run the attempted command as a rake command with the --dry-run flag. If successful, suggest
+      # to the user that they possibly meant to run the given rails command as a rake command.
+      # Append the help message.
+      #
+      #   Example:
+      #   $ rails db:migrate
+      #   Error: Command 'db:migrate' not recognized
+      #   Did you mean: `$ rake db:migrate` ?
+      #   (Help message output)
+      #
       def write_error_message(command)
         puts "Error: Command '#{command}' not recognized"
         if %x{rake #{command} --dry-run 2>&1 } && $?.success?
diff --git a/railties/lib/rails/commands/console.rb b/railties/lib/rails/commands/console.rb
index 35a815a34f..ea5d20ea24 100644
--- a/railties/lib/rails/commands/console.rb
+++ b/railties/lib/rails/commands/console.rb
@@ -1,14 +1,13 @@
 require 'optparse'
 require 'irb'
 require 'irb/completion'
+require 'rails/commands/console_helper'
 
 module Rails
   class Console
-    class << self
-      def start(*args)
-        new(*args).start
-      end
+    include ConsoleHelper
 
+    class << self
       def parse_arguments(arguments)
         options = {}
 
@@ -21,23 +20,8 @@ module Rails
           opt.parse!(arguments)
         end
 
-        if arguments.first && arguments.first[0] != '-'
-          env = arguments.first
-          if available_environments.include? env
-            options[:environment] = env
-          else
-            options[:environment] = %w(production development test).detect {|e| e =~ /^#{env}/} || env
-          end
-        end
-
-        options
+        set_options_env(arguments, options)
       end
-
-      private
-
-        def available_environments
-          Dir['config/environments/*.rb'].map { |fname| File.basename(fname, '.*') }
-        end
     end
 
     attr_reader :options, :app, :console
@@ -57,12 +41,9 @@ module Rails
     end
 
     def environment
-      options[:environment] ||= ENV['RAILS_ENV'] || ENV['RACK_ENV'] || 'development'
-    end
-
-    def environment?
-      environment
+      options[:environment] ||= super
     end
+    alias_method :environment?, :environment
 
     def set_environment!
       Rails.env = environment
@@ -79,7 +60,7 @@ module Rails
       end
 
       if defined?(console::ExtendCommandBundle)
-        console::ExtendCommandBundle.send :include, Rails::ConsoleMethods
+        console::ExtendCommandBundle.include(Rails::ConsoleMethods)
       end
       console.start
     end
diff --git a/railties/lib/rails/commands/console_helper.rb b/railties/lib/rails/commands/console_helper.rb
new file mode 100644
index 0000000000..8ee0b60012
--- /dev/null
+++ b/railties/lib/rails/commands/console_helper.rb
@@ -0,0 +1,34 @@
+require 'active_support/concern'
+
+module Rails
+  module ConsoleHelper # :nodoc:
+    extend ActiveSupport::Concern
+
+    module ClassMethods
+      def start(*args)
+        new(*args).start
+      end
+      
+      private
+        def set_options_env(arguments, options)
+          if arguments.first && arguments.first[0] != '-'
+            env = arguments.first
+            if available_environments.include? env
+              options[:environment] = env
+            else
+              options[:environment] = %w(production development test).detect { |e| e =~ /^#{env}/ } || env
+            end
+          end
+          options
+        end
+
+        def available_environments
+          Dir['config/environments/*.rb'].map { |fname| File.basename(fname, '.*') }
+        end  
+    end
+
+    def environment
+      ENV["RAILS_ENV"] || ENV["RACK_ENV"] || "development"
+    end
+  end
+end
\ No newline at end of file
diff --git a/railties/lib/rails/commands/dbconsole.rb b/railties/lib/rails/commands/dbconsole.rb
index 63bf8b11ba..dca60f948f 100644
--- a/railties/lib/rails/commands/dbconsole.rb
+++ b/railties/lib/rails/commands/dbconsole.rb
@@ -1,13 +1,49 @@
 require 'erb'
 require 'yaml'
 require 'optparse'
+require 'rails/commands/console_helper'
 
 module Rails
   class DBConsole
+    include ConsoleHelper
+
     attr_reader :arguments
 
-    def self.start
-      new.start
+    class << self
+      def parse_arguments(arguments)
+        options = {}
+
+        OptionParser.new do |opt|
+          opt.banner = "Usage: rails dbconsole [environment] [options]"
+          opt.on("-p", "--include-password", "Automatically provide the password from database.yml") do |v|
+            options['include_password'] = true
+          end
+
+          opt.on("--mode [MODE]", ['html', 'list', 'line', 'column'],
+            "Automatically put the sqlite3 database in the specified mode (html, list, line, column).") do |mode|
+              options['mode'] = mode
+          end
+
+          opt.on("--header") do |h|
+            options['header'] = h
+          end
+
+          opt.on("-h", "--help", "Show this help message.") do
+            puts opt
+            exit
+          end
+
+          opt.on("-e", "--environment=name", String,
+            "Specifies the environment to run this console under (test/development/production).",
+            "Default: development"
+          ) { |v| options[:environment] = v.strip }
+
+          opt.parse!(arguments)
+          abort opt.to_s unless (0..1).include?(arguments.size)
+        end
+
+        set_options_env(arguments, options)
+      end
     end
 
     def initialize(arguments = ARGV)
@@ -15,7 +51,7 @@ module Rails
     end
 
     def start
-      options = parse_arguments(arguments)
+      options = self.class.parse_arguments(arguments)
       ENV['RAILS_ENV'] = options[:environment] || environment
 
       case config["adapter"]
@@ -50,9 +86,6 @@ module Rails
         ENV['PGPASSWORD'] = config["password"].to_s if config["password"] && options['include_password']
         find_cmd_and_exec('psql', config["database"])
 
-      when "sqlite"
-        find_cmd_and_exec('sqlite', config["database"])
-
       when "sqlite3"
         args = []
 
@@ -89,7 +122,7 @@ module Rails
         find_cmd_and_exec("sqsh", *args)
 
       else
-        abort "Unknown command-line client for #{config['database']}. Submit a Rails patch to add support!"
+        abort "Unknown command-line client for #{config['database']}."
       end
     end
 
@@ -104,88 +137,37 @@ module Rails
     end
 
     def environment
-      if Rails.respond_to?(:env)
-        Rails.env
-      else
-        ENV["RAILS_ENV"] || ENV["RACK_ENV"] || "development"
-      end
+      Rails.respond_to?(:env) ? Rails.env : super
     end
 
     protected
+      def configurations
+        require APP_PATH
+        ActiveRecord::Base.configurations = Rails.application.config.database_configuration
+        ActiveRecord::Base.configurations
+      end
 
-    def configurations
-      require APP_PATH
-      ActiveRecord::Base.configurations = Rails.application.config.database_configuration
-      ActiveRecord::Base.configurations
-    end
-
-    def parse_arguments(arguments)
-      options = {}
-
-      OptionParser.new do |opt|
-        opt.banner = "Usage: rails dbconsole [environment] [options]"
-        opt.on("-p", "--include-password", "Automatically provide the password from database.yml") do |v|
-          options['include_password'] = true
-        end
-
-        opt.on("--mode [MODE]", ['html', 'list', 'line', 'column'],
-          "Automatically put the sqlite3 database in the specified mode (html, list, line, column).") do |mode|
-            options['mode'] = mode
-        end
+      def find_cmd_and_exec(commands, *args)
+        commands = Array(commands)
 
-        opt.on("--header") do |h|
-          options['header'] = h
+        dirs_on_path = ENV['PATH'].to_s.split(File::PATH_SEPARATOR)
+        unless (ext = RbConfig::CONFIG['EXEEXT']).empty?
+          commands = commands.map{|cmd| "#{cmd}#{ext}"}
         end
 
-        opt.on("-h", "--help", "Show this help message.") do
-          puts opt
-          exit
+        full_path_command = nil
+        found = commands.detect do |cmd|
+          dirs_on_path.detect do |path|
+            full_path_command = File.join(path, cmd)
+            File.file?(full_path_command) && File.executable?(full_path_command)
+          end
         end
 
-        opt.on("-e", "--environment=name", String,
-          "Specifies the environment to run this console under (test/development/production).",
-          "Default: development"
-        ) { |v| options[:environment] = v.strip }
-
-        opt.parse!(arguments)
-        abort opt.to_s unless (0..1).include?(arguments.size)
-      end
-
-      if arguments.first && arguments.first[0] != '-'
-        env = arguments.first
-        if available_environments.include? env
-          options[:environment] = env
+        if found
+          exec full_path_command, *args
         else
-          options[:environment] = %w(production development test).detect {|e| e =~ /^#{env}/} || env
+          abort("Couldn't find database client: #{commands.join(', ')}. Check your $PATH and try again.")
         end
       end
-
-      options
-    end
-
-    def available_environments
-      Dir['config/environments/*.rb'].map { |fname| File.basename(fname, '.*') }
-    end
-
-    def find_cmd_and_exec(commands, *args)
-      commands = Array(commands)
-
-      dirs_on_path = ENV['PATH'].to_s.split(File::PATH_SEPARATOR)
-      commands += commands.map{|cmd| "#{cmd}.exe"} if RbConfig::CONFIG['host_os'] =~ /mswin|mingw/
-
-      full_path_command = nil
-      found = commands.detect do |cmd|
-        dirs_on_path.detect do |path|
-          full_path_command = File.join(path, cmd)
-          File.file?(full_path_command) && File.executable?(full_path_command)
-        end
-      end
-
-      if found
-        exec full_path_command, *args
-      else
-        abort("Couldn't find database client: #{commands.join(', ')}. Check your $PATH and try again.")
-      end
-    end
   end
 end
diff --git a/railties/lib/rails/commands/server.rb b/railties/lib/rails/commands/server.rb
index bc8f1a8dea..d3ea441f8e 100644
--- a/railties/lib/rails/commands/server.rb
+++ b/railties/lib/rails/commands/server.rb
@@ -34,6 +34,9 @@ module Rails
           opts.on("-P", "--pid=pid", String,
                   "Specifies the PID file.",
                   "Default: tmp/pids/server.pid") { |v| options[:pid] = v }
+          opts.on("-C", "--[no-]dev-caching",
+                  "Specifies whether to perform caching in development.",
+                  "true or false") { |v| options[:caching] = v }
 
           opts.separator ""
 
@@ -67,6 +70,7 @@ module Rails
       print_boot_information
       trap(:INT) { exit }
       create_tmp_directories
+      setup_dev_caching
       log_to_stdout if options[:log_stdout]
 
       super
@@ -77,37 +81,32 @@ module Rails
     end
 
     def middleware
-      middlewares = []
-      middlewares << [::Rack::ContentLength]
-
-      # FIXME: add Rack::Lock in the case people are using webrick.
-      # This is to remain backwards compatible for those who are
-      # running webrick in production. We should consider removing this
-      # in development.
-      if server.name == 'Rack::Handler::WEBrick'
-        middlewares << [::Rack::Lock]
-      end
-
-      Hash.new(middlewares)
-    end
-
-    def log_path
-      "log/#{options[:environment]}.log"
+      Hash.new([])
     end
 
     def default_options
       super.merge({
-        Port:               3000,
+        Port:               ENV.fetch('PORT', 3000).to_i,
         DoNotReverseLookup: true,
         environment:        (ENV['RAILS_ENV'] || ENV['RACK_ENV'] || "development").dup,
         daemonize:          false,
-        pid:                File.expand_path("tmp/pids/server.pid"),
-        config:             File.expand_path("config.ru")
+        caching:            false,
+        pid:                File.expand_path("tmp/pids/server.pid")
       })
     end
 
     private
 
+      def setup_dev_caching
+        return unless options[:environment] == "development"
+
+        if options[:caching] == false
+          delete_cache_file
+        elsif options[:caching]
+          create_cache_file
+        end
+      end
+
       def print_boot_information
         url = "#{options[:SSLEnable] ? 'https' : 'http'}://#{options[:Host]}:#{options[:Port]}"
         puts "=> Booting #{ActiveSupport::Inflector.demodulize(server)}"
@@ -117,6 +116,14 @@ module Rails
         puts "=> Ctrl-C to shutdown server" unless options[:daemonize]
       end
 
+      def create_cache_file
+        FileUtils.touch("tmp/caching-dev.txt")
+      end
+
+      def delete_cache_file
+        FileUtils.rm("tmp/caching-dev.txt") if File.exist?("tmp/caching-dev.txt")
+      end
+
       def create_tmp_directories
         %w(cache pids sockets).each do |dir_to_make|
           FileUtils.mkdir_p(File.join(Rails.root, 'tmp', dir_to_make))
diff --git a/railties/lib/rails/commands/test.rb b/railties/lib/rails/commands/test.rb
new file mode 100644
index 0000000000..dd069f081f
--- /dev/null
+++ b/railties/lib/rails/commands/test.rb
@@ -0,0 +1,9 @@
+require "rails/test_unit/minitest_plugin"
+
+if defined?(ENGINE_ROOT)
+  $: << File.expand_path('test', ENGINE_ROOT)
+else
+  $: << File.expand_path('../../test', APP_PATH)
+end
+
+exit Minitest.run(ARGV)
diff --git a/railties/lib/rails/configuration.rb b/railties/lib/rails/configuration.rb
index f99cec04c5..30eafd59f2 100644
--- a/railties/lib/rails/configuration.rb
+++ b/railties/lib/rails/configuration.rb
@@ -33,8 +33,9 @@ module Rails
     #     config.middleware.delete ActionDispatch::Flash
     #
     class MiddlewareStackProxy
-      def initialize
-        @operations = []
+      def initialize(operations = [], delete_operations = [])
+        @operations = operations
+        @delete_operations = delete_operations
       end
 
       def insert_before(*args, &block)
@@ -56,7 +57,7 @@ module Rails
       end
 
       def delete(*args, &block)
-        @operations << [__method__, args, block]
+        @delete_operations << [__method__, args, block]
       end
 
       def unshift(*args, &block)
@@ -64,15 +65,29 @@ module Rails
       end
 
       def merge_into(other) #:nodoc:
-        @operations.each do |operation, args, block|
+        (@operations + @delete_operations).each do |operation, args, block|
           other.send(operation, *args, &block)
         end
+
         other
       end
+
+      def +(other) # :nodoc:
+        MiddlewareStackProxy.new(@operations + other.operations, @delete_operations + other.delete_operations)
+      end
+
+      protected
+        def operations
+          @operations
+        end
+
+        def delete_operations
+          @delete_operations
+        end
     end
 
     class Generators #:nodoc:
-      attr_accessor :aliases, :options, :templates, :fallbacks, :colorize_logging
+      attr_accessor :aliases, :options, :templates, :fallbacks, :colorize_logging, :api_only
       attr_reader :hidden_namespaces
 
       def initialize
@@ -81,6 +96,7 @@ module Rails
         @fallbacks = {}
         @templates = []
         @colorize_logging = true
+        @api_only = false
         @hidden_namespaces = []
       end
 
diff --git a/railties/lib/rails/console/app.rb b/railties/lib/rails/console/app.rb
index 2a69c26deb..ac5836a588 100644
--- a/railties/lib/rails/console/app.rb
+++ b/railties/lib/rails/console/app.rb
@@ -18,6 +18,11 @@ module Rails
       app = Rails.application
       session = ActionDispatch::Integration::Session.new(app)
       yield session if block_given?
+
+      # This makes app.url_for and app.foo_path available in the console
+      session.extend(app.routes.url_helpers)
+      session.extend(app.routes.mounted_helpers)
+
       session
     end
 
diff --git a/railties/lib/rails/console/helpers.rb b/railties/lib/rails/console/helpers.rb
index b775f1ff8d..a33f71dc5b 100644
--- a/railties/lib/rails/console/helpers.rb
+++ b/railties/lib/rails/console/helpers.rb
@@ -4,7 +4,7 @@ module Rails
     #
     # This method assumes an +ApplicationController+ exists, and it extends +ActionController::Base+
     def helper
-      @helper ||= ApplicationController.helpers
+      ApplicationController.helpers
     end
 
     # Gets a new instance of a controller object.
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index a338f31f15..5757d235d2 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -2,11 +2,12 @@ require 'rails/railtie'
 require 'rails/engine/railties'
 require 'active_support/core_ext/module/delegation'
 require 'pathname'
+require 'thread'
 
 module Rails
   # <tt>Rails::Engine</tt> allows you to wrap a specific Rails application or subset of
   # functionality and share it with other applications or within a larger packaged application.
-  # Since Rails 3.0, every <tt>Rails::Application</tt> is just an engine, which allows for simple
+  # Every <tt>Rails::Application</tt> is just an engine, which allows for simple
   # feature and application sharing.
   #
   # Any <tt>Rails::Engine</tt> is also a <tt>Rails::Railtie</tt>, so the same
@@ -15,10 +16,9 @@ module Rails
   #
   # == Creating an Engine
   #
-  # In Rails versions prior to 3.0, your gems automatically behaved as engines, however,
-  # this coupled Rails to Rubygems. Since Rails 3.0, if you want a gem to automatically
-  # behave as an engine, you have to specify an +Engine+ for it somewhere inside
-  # your plugin's +lib+ folder (similar to how we specify a +Railtie+):
+  # If you want a gem to behave as an engine, you have to specify an +Engine+
+  # for it somewhere inside your plugin's +lib+ folder (similar to how we
+  # specify a +Railtie+):
   #
   #   # lib/my_engine.rb
   #   module MyEngine
@@ -69,10 +69,9 @@ module Rails
   #
   # == Paths
   #
-  # Since Rails 3.0, applications and engines have more flexible path configuration (as
-  # opposed to the previous hardcoded path configuration). This means that you are not
-  # required to place your controllers at <tt>app/controllers</tt>, but in any place
-  # which you find convenient.
+  # Applications and engines have flexible path configuration, meaning that you
+  # are not required to place your controllers at <tt>app/controllers</tt>, but
+  # in any place which you find convenient.
   #
   # For example, let's suppose you want to place your controllers in <tt>lib/controllers</tt>.
   # You can set that as an option:
@@ -206,42 +205,51 @@ module Rails
   # With such an engine, everything that is inside the +MyEngine+ module will be isolated from
   # the application.
   #
-  # Consider such controller:
+  # Consider this controller:
   #
   #   module MyEngine
   #     class FooController < ActionController::Base
   #     end
   #   end
   #
-  # If an engine is marked as isolated, +FooController+ has access only to helpers from +Engine+ and
-  # <tt>url_helpers</tt> from <tt>MyEngine::Engine.routes</tt>.
+  # If the +MyEngine+ engine is marked as isolated, +FooController+ only has
+  # access to helpers from +MyEngine+, and <tt>url_helpers</tt> from
+  # <tt>MyEngine::Engine.routes</tt>.
   #
-  # The next thing that changes in isolated engines is the behavior of routes. Normally, when you namespace
-  # your controllers, you also need to do namespace all your routes. With an isolated engine,
-  # the namespace is applied by default, so you can ignore it in routes:
+  # The next thing that changes in isolated engines is the behavior of routes.
+  # Normally, when you namespace your controllers, you also need to namespace
+  # the related routes. With an isolated engine, the engine's namespace is
+  # automatically applied, so you don't need to specify it explicity in your
+  # routes:
   #
   #   MyEngine::Engine.routes.draw do
   #     resources :articles
   #   end
   #
-  # The routes above will automatically point to <tt>MyEngine::ArticlesController</tt>. Furthermore, you don't
-  # need to use longer url helpers like <tt>my_engine_articles_path</tt>. Instead, you should simply use
-  # <tt>articles_path</tt> as you would do with your application.
+  # If +MyEngine+ is isolated, The routes above will point to
+  # <tt>MyEngine::ArticlesController</tt>. You also don't need to use longer
+  # url helpers like +my_engine_articles_path+. Instead, you should simply use
+  # +articles_path+, like you would do with your main application.
   #
-  # To make that behavior consistent with other parts of the framework, an isolated engine also has influence on
-  # <tt>ActiveModel::Naming</tt>. When you use a namespaced model, like <tt>MyEngine::Article</tt>, it will normally
-  # use the prefix "my_engine". In an isolated engine, the prefix will be omitted in url helpers and
-  # form fields for convenience.
+  # To make this behavior consistent with other parts of the framework,
+  # isolated engines also have an effect on <tt>ActiveModel::Naming</tt>. In a
+  # normal Rails app, when you use a namespaced model such as
+  # <tt>Namespace::Article</tt>, <tt>ActiveModel::Naming</tt> will generate
+  # names with the prefix "namespace". In an isolated engine, the prefix will
+  # be omitted in url helpers and form fields, for convenience.
   #
-  #   polymorphic_url(MyEngine::Article.new) # => "articles_path"
+  #   polymorphic_url(MyEngine::Article.new)
+  #   # => "articles_path" # not "my_engine_articles_path"
   #
   #   form_for(MyEngine::Article.new) do
   #     text_field :title # => <input type="text" name="article[title]" id="article_title" />
   #   end
   #
-  # Additionally, an isolated engine will set its name according to namespace, so
-  # MyEngine::Engine.engine_name will be "my_engine". It will also set MyEngine.table_name_prefix
-  # to "my_engine_", changing the MyEngine::Article model to use the my_engine_articles table.
+  # Additionally, an isolated engine will set its own name according to its
+  # namespace, so <tt>MyEngine::Engine.engine_name</tt> will return
+  # "my_engine". It will also set +MyEngine.table_name_prefix+ to "my_engine_",
+  # meaning for example that <tt>MyEngine::Article</tt> will use the
+  # +my_engine_articles+ database table by default.
   #
   # == Using Engine's routes outside Engine
   #
@@ -296,7 +304,7 @@ module Rails
   #     helper MyEngine::SharedEngineHelper
   #   end
   #
-  # If you want to include all of the engine's helpers, you can use #helper method on an engine's
+  # If you want to include all of the engine's helpers, you can use the #helper method on an engine's
   # instance:
   #
   #   class ApplicationController < ActionController::Base
@@ -312,7 +320,7 @@ module Rails
   # Engines can have their own migrations. The default path for migrations is exactly the same
   # as in application: <tt>db/migrate</tt>
   #
-  # To use engine's migrations in application you can use rake task, which copies them to
+  # To use engine's migrations in application you can use the rake task below, which copies them to
   # application's dir:
   #
   #   rake ENGINE_NAME:install:migrations
@@ -328,7 +336,7 @@ module Rails
   #
   # == Loading priority
   #
-  # In order to change engine's priority you can use +config.railties_order+ in main application.
+  # In order to change engine's priority you can use +config.railties_order+ in the main application.
   # It will affect the priority of loading views, helpers, assets and all the other files
   # related to engine or application.
   #
@@ -350,12 +358,7 @@ module Rails
           Rails::Railtie::Configuration.eager_load_namespaces << base
 
           base.called_from = begin
-            call_stack = if Kernel.respond_to?(:caller_locations)
-              caller_locations.map { |l| l.absolute_path || l.path }
-            else
-              # Remove the line number from backtraces making sure we don't leave anything behind
-              caller.map { |p| p.sub(/:\d+.*/, '') }
-            end
+            call_stack = caller_locations.map { |l| l.absolute_path || l.path }
 
             File.dirname(call_stack.detect { |p| p !~ %r[railties[\w.-]*/lib/rails|rack[\w.-]*/lib/rack] })
           end
@@ -405,7 +408,7 @@ module Rails
         end
       end
 
-      # Finds engine with given path
+      # Finds engine with given path.
       def find(path)
         expanded_path = File.expand_path path
         Rails::Engine.subclasses.each do |klass|
@@ -427,6 +430,7 @@ module Rails
       @env_config          = nil
       @helpers             = nil
       @routes              = nil
+      @app_build_lock      = Mutex.new
       super
     end
 
@@ -484,7 +488,7 @@ module Rails
         helpers = Module.new
         all = ActionController::Base.all_helpers_from_path(helpers_paths)
         ActionController::Base.modules_for_helpers(all).each do |mod|
-          helpers.send(:include, mod)
+          helpers.include(mod)
         end
         helpers
       end
@@ -497,10 +501,13 @@ module Rails
 
     # Returns the underlying rack application for this engine.
     def app
-      @app ||= begin
-        config.middleware = config.middleware.merge_into(default_middleware_stack)
-        config.middleware.build(endpoint)
-      end
+      @app || @app_build_lock.synchronize {
+        @app ||= begin
+          stack = default_middleware_stack
+          config.middleware = build_middleware.merge_into(stack)
+          config.middleware.build(endpoint)
+        end
+      }
     end
 
     # Returns the endpoint for this engine. If none is registered,
@@ -511,24 +518,19 @@ module Rails
 
     # Define the Rack API for this engine.
     def call(env)
-      env.merge!(env_config)
-      if env['SCRIPT_NAME']
-        env["ROUTES_#{routes.object_id}_SCRIPT_NAME"] = env['SCRIPT_NAME'].dup
-      end
-      app.call(env)
+      req = build_request env
+      app.call req.env
     end
 
     # Defines additional Rack env configuration that is added on each call.
     def env_config
-      @env_config ||= {
-        'action_dispatch.routes' => routes
-      }
+      @env_config ||= {}
     end
 
     # Defines the routes for this engine. If a block is given to
     # routes, it is appended to the engine.
     def routes
-      @routes ||= ActionDispatch::Routing::RouteSet.new
+      @routes ||= ActionDispatch::Routing::RouteSet.new_with_config(config)
       @routes.append(&Proc.new) if block_given?
       @routes
     end
@@ -559,7 +561,7 @@ module Rails
     # and the load_once paths.
     #
     # This needs to be an initializer, since it needs to run once
-    # per engine and get the engine as a block parameter
+    # per engine and get the engine as a block parameter.
     initializer :set_autoload_paths, before: :bootstrap_hook do
       ActiveSupport::Dependencies.autoload_paths.unshift(*_all_autoload_paths)
       ActiveSupport::Dependencies.autoload_once_paths.unshift(*_all_autoload_once_paths)
@@ -582,7 +584,7 @@ module Rails
     # I18n load paths are a special case since the ones added
     # later have higher priority.
     initializer :add_locales do
-      config.i18n.railties_load_path.concat(paths["config/locales"].existent)
+      config.i18n.railties_load_path << paths["config/locales"]
     end
 
     initializer :add_view_paths do
@@ -599,12 +601,6 @@ module Rails
       end
     end
 
-    initializer :append_assets_path, group: :all do |app|
-      app.config.assets.paths.unshift(*paths["vendor/assets"].existent_directories)
-      app.config.assets.paths.unshift(*paths["lib/assets"].existent_directories)
-      app.config.assets.paths.unshift(*paths["app/assets"].existent_directories)
-    end
-
     initializer :prepend_helpers_path do |app|
       if !isolated? || (app == self)
         app.config.helpers_paths.unshift(*paths["app/helpers"].existent)
@@ -690,5 +686,19 @@ module Rails
     def _all_load_paths #:nodoc:
       @_all_load_paths ||= (config.paths.load_paths + _all_autoload_paths).uniq
     end
+
+    private
+
+    def build_request(env)
+      env.merge!(env_config)
+      req = ActionDispatch::Request.new env
+      req.routes = routes
+      req.engine_script_name = req.script_name
+      req
+    end
+
+    def build_middleware
+      config.middleware
+    end
   end
 end
diff --git a/railties/lib/rails/engine/commands.rb b/railties/lib/rails/engine/commands.rb
index f39f926109..a6d87b78e4 100644
--- a/railties/lib/rails/engine/commands.rb
+++ b/railties/lib/rails/engine/commands.rb
@@ -2,7 +2,8 @@ ARGV << '--help' if ARGV.empty?
 
 aliases = {
   "g" => "generate",
-  "d" => "destroy"
+  "d" => "destroy",
+  "t" => "test"
 }
 
 command = ARGV.shift
@@ -12,7 +13,7 @@ require ENGINE_PATH
 engine = ::Rails::Engine.find(ENGINE_ROOT)
 
 case command
-when 'generate', 'destroy'
+when 'generate', 'destroy', 'test'
   require 'rails/generators'
   Rails::Generators.namespace = engine.railtie_namespace
   engine.load_generators
@@ -30,6 +31,7 @@ Usage: rails COMMAND [ARGS]
 The common Rails commands available for engines are:
  generate    Generate new code (short-cut alias: "g")
  destroy     Undo code generated with "generate" (short-cut alias: "d")
+ test        Run tests (short-cut alias: "t")
 
 All commands can be run with -h for more information.
 
diff --git a/railties/lib/rails/engine/configuration.rb b/railties/lib/rails/engine/configuration.rb
index 62a4139d07..8cadbc3ddd 100644
--- a/railties/lib/rails/engine/configuration.rb
+++ b/railties/lib/rails/engine/configuration.rb
@@ -4,17 +4,14 @@ module Rails
   class Engine
     class Configuration < ::Rails::Railtie::Configuration
       attr_reader :root
-      attr_writer :middleware, :eager_load_paths, :autoload_once_paths, :autoload_paths
+      attr_accessor :middleware
+      attr_writer :eager_load_paths, :autoload_once_paths, :autoload_paths
 
       def initialize(root=nil)
         super()
         @root = root
         @generators = app_generators.dup
-      end
-
-      # Returns the middleware stack for the engine.
-      def middleware
-        @middleware ||= Rails::Configuration::MiddlewareStackProxy.new
+        @middleware = Rails::Configuration::MiddlewareStackProxy.new
       end
 
       # Holds generators configuration:
@@ -29,7 +26,7 @@ module Rails
       #
       #   config.generators.colorize_logging = false
       #
-      def generators #:nodoc:
+      def generators
         @generators ||= Rails::Configuration::Generators.new
         yield(@generators) if block_given?
         @generators
diff --git a/railties/lib/rails/generators.rb b/railties/lib/rails/generators.rb
index e25c364178..2645102619 100644
--- a/railties/lib/rails/generators.rb
+++ b/railties/lib/rails/generators.rb
@@ -33,6 +33,7 @@ module Rails
         scaffold_controller: '-c',
         stylesheets: '-y',
         stylesheet_engine: '-se',
+        scaffold_stylesheet: '-ss',
         template_engine: '-e',
         test_framework: '-t'
       },
@@ -44,6 +45,7 @@ module Rails
 
     DEFAULT_OPTIONS = {
       rails: {
+        api: false,
         assets: true,
         force_plural: false,
         helper: true,
@@ -56,12 +58,14 @@ module Rails
         scaffold_controller: :scaffold_controller,
         stylesheets: true,
         stylesheet_engine: :css,
+        scaffold_stylesheet: true,
         test_framework: false,
         template_engine: :erb
       }
     }
 
     def self.configure!(config) #:nodoc:
+      api_only! if config.api_only
       no_color! unless config.colorize_logging
       aliases.deep_merge! config.aliases
       options.deep_merge! config.options
@@ -99,6 +103,21 @@ module Rails
       @fallbacks ||= {}
     end
 
+    # Configure generators for API only applications. It basically hides
+    # everything that is usually browser related, such as assets and session
+    # migration generators, and completely disable views, helpers and assets
+    # so generators such as scaffold won't create them.
+    def self.api_only!
+      hide_namespaces "assets", "helper", "css", "js"
+
+      options[:rails].merge!(
+        api: true,
+        assets: false,
+        helper: false,
+        template_engine: nil
+      )
+    end
+
     # Remove the color from output.
     def self.no_color!
       Thor::Base.shell = Thor::Shell::Basic
@@ -156,10 +175,10 @@ module Rails
         args << "--help" if args.empty? && klass.arguments.any?(&:required?)
         klass.start(args, config)
       else
-        options     = sorted_groups.map(&:last).flatten
+        options     = sorted_groups.flat_map(&:last)
         suggestions = options.sort_by {|suggested| levenshtein_distance(namespace.to_s, suggested) }.first(3)
         msg =  "Could not find generator '#{namespace}'. "
-        msg << "Maybe you meant #{ suggestions.map {|s| "'#{s}'"}.join(" or ") }\n"
+        msg << "Maybe you meant #{ suggestions.map {|s| "'#{s}'"}.to_sentence(last_word_connector: " or ", locale: :en) }\n"
         msg << "Run `rails generate --help` for more options."
         puts msg
       end
@@ -260,19 +279,20 @@ module Rails
         t = str2
         n = s.length
         m = t.length
-        max = n/2
 
         return m if (0 == n)
         return n if (0 == m)
-        return n if (n - m).abs > max
 
         d = (0..m).to_a
         x = nil
 
-        str1.each_char.each_with_index do |char1,i|
+        # avoid duplicating an enumerable object in the loop
+        str2_codepoint_enumerable = str2.each_codepoint
+
+        str1.each_codepoint.with_index do |char1, i|
           e = i+1
 
-          str2.each_char.each_with_index do |char2,j|
+          str2_codepoint_enumerable.with_index do |char2, j|
             cost = (char1 == char2) ? 0 : 1
             x = [
                  d[j+1] + 1, # insertion
@@ -286,7 +306,7 @@ module Rails
           d[m] = x
         end
 
-        return x
+        x
       end
 
       # Prints a list of generators.
diff --git a/railties/lib/rails/generators/actions.rb b/railties/lib/rails/generators/actions.rb
index e35015f630..b4356f71e0 100644
--- a/railties/lib/rails/generators/actions.rb
+++ b/railties/lib/rails/generators/actions.rb
@@ -63,12 +63,26 @@ module Rails
 
       # Add the given source to +Gemfile+
       #
+      # If block is given, gem entries in block are wrapped into the source group.
+      #
       #   add_source "http://gems.github.com/"
-      def add_source(source, options={})
+      #
+      #   add_source "http://gems.github.com/" do
+      #     gem "rspec-rails"
+      #   end
+      def add_source(source, options={}, &block)
         log :source, source
 
         in_root do
-          prepend_file "Gemfile", "source #{quote(source)}\n", verbose: false
+          if block
+            append_file "Gemfile", "source #{quote(source)} do", force: true
+            @in_group = true
+            instance_eval(&block)
+            @in_group = false
+            append_file "Gemfile", "\nend\n", force: true
+          else
+            prepend_file "Gemfile", "source #{quote(source)}\n", verbose: false
+          end
         end
       end
 
@@ -78,11 +92,11 @@ module Rails
       # file in <tt>config/environments</tt>.
       #
       #   environment do
-      #     "config.autoload_paths += %W(#{config.root}/extras)"
+      #     "config.action_controller.asset_host = 'cdn.provider.com'"
       #   end
       #
       #   environment(nil, env: "development") do
-      #     "config.autoload_paths += %W(#{config.root}/extras)"
+      #     "config.action_controller.asset_host = 'localhost:3000'"
       #   end
       def environment(data=nil, options={})
         sentinel = /class [a-z_:]+ < Rails::Application/i
@@ -218,10 +232,10 @@ module Rails
       #   route "root 'welcome#index'"
       def route(routing_code)
         log :route, routing_code
-        sentinel = /\.routes\.draw do\s*$/
+        sentinel = /\.routes\.draw do\s*\n/m
 
         in_root do
-          inject_into_file 'config/routes.rb', "\n  #{routing_code}", { after: sentinel, verbose: false }
+          inject_into_file 'config/routes.rb', "  #{routing_code}\n", { after: sentinel, verbose: false, force: true }
         end
       end
 
diff --git a/railties/lib/rails/generators/app_base.rb b/railties/lib/rails/generators/app_base.rb
index 71186891a3..0f44f4694e 100644
--- a/railties/lib/rails/generators/app_base.rb
+++ b/railties/lib/rails/generators/app_base.rb
@@ -69,8 +69,8 @@ module Rails
         class_option :skip_turbolinks,    type: :boolean, default: false,
                                           desc: 'Skip turbolinks gem'
 
-        class_option :skip_test_unit,     type: :boolean, aliases: '-T', default: false,
-                                          desc: 'Skip Test::Unit files'
+        class_option :skip_test,          type: :boolean, aliases: '-T', default: false,
+                                          desc: 'Skip test files'
 
         class_option :rc,                 type: :string, default: false,
                                           desc: "Path to file containing extra configuration options for rails command"
@@ -113,7 +113,6 @@ module Rails
          assets_gemfile_entry,
          javascript_gemfile_entry,
          jbuilder_gemfile_entry,
-         sdoc_gemfile_entry,
          psych_gemfile_entry,
          @extra_entries].flatten.find_all(&@gem_filter)
       end
@@ -127,7 +126,7 @@ module Rails
       def builder
         @builder ||= begin
           builder_class = get_builder_class
-          builder_class.send(:include, ActionMethods)
+          builder_class.include(ActionMethods)
           builder_class.new(self)
         end
       end
@@ -168,13 +167,17 @@ module Rails
       end
 
       def include_all_railties?
-        options.values_at(:skip_active_record, :skip_action_mailer, :skip_test_unit, :skip_sprockets).none?
+        options.values_at(:skip_active_record, :skip_action_mailer, :skip_test, :skip_sprockets).none?
       end
 
       def comment_if(value)
         options[value] ? '# ' : ''
       end
 
+      def keeps?
+        !options[:skip_keeps]
+      end
+
       def sqlite3?
         !options[:skip_active_record] && options[:database] == 'sqlite3'
       end
@@ -202,16 +205,21 @@ module Rails
       end
 
       def rails_gemfile_entry
+        dev_edge_common = [
+            GemfileEntry.github('sprockets-rails', 'rails/sprockets-rails'),
+            GemfileEntry.github('sprockets', 'rails/sprockets'),
+            GemfileEntry.github('sass-rails', 'rails/sass-rails'),
+            GemfileEntry.github('arel', 'rails/arel'),
+            GemfileEntry.github('rack', 'rack/rack')
+          ]
         if options.dev?
           [
-            GemfileEntry.path('rails', Rails::Generators::RAILS_DEV_PATH),
-            GemfileEntry.github('arel', 'rails/arel')
-          ]
+            GemfileEntry.path('rails', Rails::Generators::RAILS_DEV_PATH)
+          ] + dev_edge_common
         elsif options.edge?
           [
-            GemfileEntry.github('rails', 'rails/rails'),
-            GemfileEntry.github('arel', 'rails/arel')
-          ]
+            GemfileEntry.github('rails', 'rails/rails')
+          ] + dev_edge_common
         else
           [GemfileEntry.version('rails',
                             Rails::VERSION::STRING,
@@ -250,8 +258,6 @@ module Rails
         return [] if options[:skip_sprockets]
 
         gems = []
-        gems << GemfileEntry.version('sass-rails', '~> 5.0',
-                                     'Use SCSS for stylesheets')
 
         gems << GemfileEntry.version('uglifier',
                                    '>= 1.3.0',
@@ -261,15 +267,12 @@ module Rails
       end
 
       def jbuilder_gemfile_entry
+        return [] if options[:api]
+
         comment = 'Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder'
         GemfileEntry.version('jbuilder', '~> 2.0', comment)
       end
 
-      def sdoc_gemfile_entry
-        comment = 'bundle exec rake doc:rails generates the API under doc/api.'
-        GemfileEntry.new('sdoc', '~> 0.4.0', comment, group: :doc)
-      end
-
       def coffee_gemfile_entry
         comment = 'Use CoffeeScript for .coffee assets and views'
         if options.dev? || options.edge?
@@ -297,7 +300,7 @@ module Rails
       end
 
       def javascript_runtime_gemfile_entry
-        comment = 'See https://github.com/sstephenson/execjs#readme for more supported runtimes'
+        comment = 'See https://github.com/rails/execjs#readme for more supported runtimes'
         if defined?(JRUBY_VERSION)
           GemfileEntry.version 'therubyrhino', nil, comment
         else
@@ -321,10 +324,6 @@ module Rails
         # its own vendored Thor, which could be a different version. Running both
         # things in the same process is a recipe for a night with paracetamol.
         #
-        # We use backticks and #print here instead of vanilla #system because it
-        # is easier to silence stdout in the existing test suite this way. The
-        # end-user gets the bundler commands called anyway, so no big deal.
-        #
         # We unset temporary bundler variables to load proper bundler and Gemfile.
         #
         # Thanks to James Tucker for the Gem tricks involved in this call.
@@ -332,8 +331,12 @@ module Rails
 
         require 'bundler'
         Bundler.with_clean_env do
-          output = `"#{Gem.ruby}" "#{_bundle_command}" #{command}`
-          print output unless options[:quiet]
+          full_command = %Q["#{Gem.ruby}" "#{_bundle_command}" #{command}]
+          if options[:quiet]
+            system(full_command, out: File::NULL)
+          else
+            system(full_command)
+          end
         end
       end
 
@@ -342,7 +345,7 @@ module Rails
       end
 
       def spring_install?
-        !options[:skip_spring] && Process.respond_to?(:fork) && !RUBY_PLATFORM.include?("cygwin")
+        !options[:skip_spring] && !options.dev? && Process.respond_to?(:fork) && !RUBY_PLATFORM.include?("cygwin")
       end
 
       def run_bundle
@@ -361,7 +364,7 @@ module Rails
       end
 
       def keep_file(destination)
-        create_file("#{destination}/.keep") unless options[:skip_keeps]
+        create_file("#{destination}/.keep") if keeps?
       end
     end
   end
diff --git a/railties/lib/rails/generators/base.rb b/railties/lib/rails/generators/base.rb
index 813b8b629e..c72ec400a0 100644
--- a/railties/lib/rails/generators/base.rb
+++ b/railties/lib/rails/generators/base.rb
@@ -103,12 +103,12 @@ module Rails
       #     hook_for :test_framework, as: :controller
       #   end
       #
-      # And now it will lookup at:
+      # And now it will look up at:
       #
       #   "test_unit:controller", "test_unit"
       #
-      # Similarly, if you want it to also lookup in the rails namespace, you just
-      # need to provide the :in value:
+      # Similarly, if you want it to also look up in the rails namespace, you
+      # just need to provide the :in value:
       #
       #   class AwesomeGenerator < Rails::Generators::Base
       #     hook_for :test_framework, in: :rails, as: :controller
@@ -302,13 +302,13 @@ module Rails
           default_for_option(Rails::Generators.options, name, options, options[:default])
         end
 
-        # Return default aliases for the option name given doing a lookup in
+        # Returns default aliases for the option name given doing a lookup in
         # Rails::Generators.aliases.
         def self.default_aliases_for_option(name, options)
           default_for_option(Rails::Generators.aliases, name, options, options[:aliases])
         end
 
-        # Return default for the option name given doing a lookup in config.
+        # Returns default for the option name given doing a lookup in config.
         def self.default_for_option(config, name, options, default)
           if generator_name and c = config[generator_name.to_sym] and c.key?(name)
             c[name]
diff --git a/railties/lib/rails/generators/erb/mailer/mailer_generator.rb b/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
index 7d27321610..65563aa6db 100644
--- a/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
+++ b/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
@@ -6,7 +6,7 @@ module Erb # :nodoc:
       argument :actions, type: :array, default: [], banner: "method method"
 
       def copy_view_files
-        view_base_path = File.join("app/views", class_path, file_name)
+        view_base_path = File.join("app/views", class_path, file_name + '_mailer')
         empty_directory view_base_path
 
         if self.behavior == :invoke
@@ -31,6 +31,10 @@ module Erb # :nodoc:
       def formats
         [:text, :html]
       end
+
+      def file_name
+        @_file_name ||= super.gsub(/\_mailer/i, '')
+      end
     end
   end
 end
diff --git a/railties/lib/rails/generators/erb/scaffold/templates/_form.html.erb b/railties/lib/rails/generators/erb/scaffold/templates/_form.html.erb
index d9713b0238..d99b27cb2d 100644
--- a/railties/lib/rails/generators/erb/scaffold/templates/_form.html.erb
+++ b/railties/lib/rails/generators/erb/scaffold/templates/_form.html.erb
@@ -17,6 +17,7 @@
     <%%= f.label :password %><br>
     <%%= f.password_field :password %>
   </div>
+
   <div class="field">
     <%%= f.label :password_confirmation %><br>
     <%%= f.password_field :password_confirmation %>
@@ -25,6 +26,7 @@
     <%%= f.<%= attribute.field_type %> :<%= attribute.column_name %> %>
 <% end -%>
   </div>
+
 <% end -%>
   <div class="actions">
     <%%= f.submit %>
diff --git a/railties/lib/rails/generators/erb/scaffold/templates/index.html.erb b/railties/lib/rails/generators/erb/scaffold/templates/index.html.erb
index c3b8ef1181..5f4904fee1 100644
--- a/railties/lib/rails/generators/erb/scaffold/templates/index.html.erb
+++ b/railties/lib/rails/generators/erb/scaffold/templates/index.html.erb
@@ -28,4 +28,4 @@
 
 <br>
 
-<%%= link_to 'New <%= human_name %>', new_<%= singular_table_name %>_path %>
+<%%= link_to 'New <%= singular_table_name.titleize %>', new_<%= singular_table_name %>_path %>
diff --git a/railties/lib/rails/generators/migration.rb b/railties/lib/rails/generators/migration.rb
index cd388e590a..87f2e1d42b 100644
--- a/railties/lib/rails/generators/migration.rb
+++ b/railties/lib/rails/generators/migration.rb
@@ -3,29 +3,29 @@ require 'rails/generators/actions/create_migration'
 
 module Rails
   module Generators
-    # Holds common methods for migrations. It assumes that migrations has the
-    # [0-9]*_name format and can be used by another frameworks (like Sequel)
+    # Holds common methods for migrations. It assumes that migrations have the
+    # [0-9]*_name format and can be used by other frameworks (like Sequel)
     # just by implementing the next migration version method.
     module Migration
       extend ActiveSupport::Concern
       attr_reader :migration_number, :migration_file_name, :migration_class_name
 
-      module ClassMethods
-        def migration_lookup_at(dirname) #:nodoc:
+      module ClassMethods #:nodoc:
+        def migration_lookup_at(dirname)
           Dir.glob("#{dirname}/[0-9]*_*.rb")
         end
 
-        def migration_exists?(dirname, file_name) #:nodoc:
+        def migration_exists?(dirname, file_name)
           migration_lookup_at(dirname).grep(/\d+_#{file_name}.rb$/).first
         end
 
-        def current_migration_number(dirname) #:nodoc:
+        def current_migration_number(dirname)
           migration_lookup_at(dirname).collect do |file|
             File.basename(file).split("_").first.to_i
           end.max.to_i
         end
 
-        def next_migration_number(dirname) #:nodoc:
+        def next_migration_number(dirname)
           raise NotImplementedError
         end
       end
diff --git a/railties/lib/rails/generators/named_base.rb b/railties/lib/rails/generators/named_base.rb
index 36456e64f5..243694f38e 100644
--- a/railties/lib/rails/generators/named_base.rb
+++ b/railties/lib/rails/generators/named_base.rb
@@ -18,8 +18,8 @@ module Rails
         parse_attributes! if respond_to?(:attributes)
       end
 
-      # Defines the template that would be used for the migration file.
-      # The arguments include the source template file, the migration filename etc.
+      # Overrides <tt>Thor::Actions#template</tt> so it can tell if
+      # a template is currently being created.
       no_tasks do
         def template(source, *args, &block)
           inside_template do
@@ -141,6 +141,10 @@ module Rails
           @plural_file_name ||= file_name.pluralize
         end
 
+        def fixture_file_name
+          @fixture_file_name ||= (pluralize_table_names? ? plural_file_name : file_name)
+        end
+
         def route_url
           @route_url ||= class_path.collect {|dname| "/" + dname }.join + "/" + plural_file_name
         end
@@ -179,6 +183,10 @@ module Rails
           !defined?(ActiveRecord::Base) || ActiveRecord::Base.pluralize_table_names
         end
 
+        def mountable_engine?
+          defined?(ENGINE_ROOT) && namespaced?
+        end
+
         # Add a class collisions name to be checked on class initialization. You
         # can supply a hash with a :prefix or :suffix to be tested.
         #
diff --git a/railties/lib/rails/generators/rails/app/app_generator.rb b/railties/lib/rails/generators/rails/app/app_generator.rb
index 0550bf113e..b813b083f4 100644
--- a/railties/lib/rails/generators/rails/app/app_generator.rb
+++ b/railties/lib/rails/generators/rails/app/app_generator.rb
@@ -38,7 +38,7 @@ module Rails
     end
 
     def readme
-      copy_file "README.rdoc", "README.rdoc"
+      copy_file "README.md", "README.md"
     end
 
     def gemfile
@@ -89,6 +89,7 @@ module Rails
     def config_when_updating
       cookie_serializer_config_exist = File.exist?('config/initializers/cookies_serializer.rb')
       callback_terminator_config_exist = File.exist?('config/initializers/callback_terminator.rb')
+      active_record_belongs_to_required_by_default_config_exist = File.exist?('config/initializers/active_record_belongs_to_required_by_default.rb')
 
       config
 
@@ -99,6 +100,10 @@ module Rails
       unless cookie_serializer_config_exist
         gsub_file 'config/initializers/cookies_serializer.rb', /json/, 'marshal'
       end
+
+      unless active_record_belongs_to_required_by_default_config_exist
+        remove_file 'config/initializers/active_record_belongs_to_required_by_default.rb'
+      end
     end
 
     def database_yml
@@ -125,6 +130,7 @@ module Rails
 
     def test
       empty_directory_with_keep_file 'test/fixtures'
+      empty_directory_with_keep_file 'test/fixtures/files'
       empty_directory_with_keep_file 'test/controllers'
       empty_directory_with_keep_file 'test/mailers'
       empty_directory_with_keep_file 'test/models'
@@ -135,6 +141,7 @@ module Rails
     end
 
     def tmp
+      empty_directory_with_keep_file "tmp"
       empty_directory "tmp/cache"
       empty_directory "tmp/cache/assets"
     end
@@ -168,6 +175,9 @@ module Rails
       class_option :version, type: :boolean, aliases: "-v", group: :rails,
                              desc: "Show Rails version number and quit"
 
+      class_option :api, type: :boolean,
+                         desc: "Preconfigure smaller stack for API only apps"
+
       def initialize(*args)
         super
 
@@ -178,6 +188,10 @@ module Rails
         if !options[:skip_active_record] && !DATABASES.include?(options[:database])
           raise Error, "Invalid value for --database option. Supported for preconfiguration are: #{DATABASES.join(", ")}."
         end
+
+        # Force sprockets to be skipped when generating API only apps.
+        # Can't modify options hash as it's frozen by default.
+        self.options = options.merge(skip_sprockets: true, skip_javascript: true).freeze if options[:api]
       end
 
       public_task :set_default_accessors!
@@ -234,7 +248,7 @@ module Rails
       end
 
       def create_test_files
-        build(:test) unless options[:skip_test_unit]
+        build(:test) unless options[:skip_test]
       end
 
       def create_tmp_files
@@ -245,6 +259,28 @@ module Rails
         build(:vendor)
       end
 
+      def delete_app_assets_if_api_option
+        if options[:api]
+          remove_dir 'app/assets'
+          remove_dir 'lib/assets'
+          remove_dir 'tmp/cache/assets'
+          remove_dir 'vendor/assets'
+        end
+      end
+
+      def delete_app_helpers_if_api_option
+        if options[:api]
+          remove_dir 'app/helpers'
+          remove_dir 'test/helpers'
+        end
+      end
+
+      def delete_app_views_if_api_option
+        if options[:api]
+          remove_dir 'app/views'
+        end
+      end
+
       def delete_js_folder_skipping_javascript
         if options[:skip_javascript]
           remove_dir 'app/assets/javascripts'
@@ -257,6 +293,19 @@ module Rails
         end
       end
 
+      def delete_active_record_initializers_skipping_active_record
+        if options[:skip_active_record]
+          remove_file 'config/initializers/active_record_belongs_to_required_by_default.rb'
+        end
+      end
+
+      def delete_non_api_initializers_if_api_option
+        if options[:api]
+          remove_file 'config/initializers/session_store.rb'
+          remove_file 'config/initializers/cookies_serializer.rb'
+        end
+      end
+
       def finish_template
         build(:leftovers)
       end
@@ -307,7 +356,9 @@ module Rails
         if app_const =~ /^\d/
           raise Error, "Invalid application name #{app_name}. Please give a name which does not start with numbers."
         elsif RESERVED_NAMES.include?(app_name)
-          raise Error, "Invalid application name #{app_name}. Please give a name which does not match one of the reserved rails words."
+          raise Error, "Invalid application name #{app_name}. Please give a " \
+                       "name which does not match one of the reserved rails " \
+                       "words: #{RESERVED_NAMES.join(", ")}"
         elsif Object.const_defined?(app_const_base)
           raise Error, "Invalid application name #{app_name}, constant #{app_const_base} is already in use. Please choose another application name."
         end
diff --git a/railties/lib/rails/generators/rails/app/templates/Gemfile b/railties/lib/rails/generators/rails/app/templates/Gemfile
index 143673f711..975be07622 100644
--- a/railties/lib/rails/generators/rails/app/templates/Gemfile
+++ b/railties/lib/rails/generators/rails/app/templates/Gemfile
@@ -21,29 +21,35 @@ source 'https://rubygems.org'
 # Use Capistrano for deployment
 # gem 'capistrano-rails', group: :development
 
-group :development, :test do
+<%- if options.api? -%>
+# Use ActiveModelSerializers to serialize JSON responses
+gem 'active_model_serializers', '~> 0.10.0.rc2'
+
+# Use Rack CORS for handling Cross-Origin Resource Sharing (CORS), making cross-origin AJAX possible
+# gem 'rack-cors'
+
+<%- end -%>
 <% if RUBY_ENGINE == 'ruby' -%>
+group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
   gem 'byebug'
+end
 
+group :development do
+<%- unless options.api? -%>
   # Access an IRB console on exception pages or by using <%%= console %> in views
   <%- if options.dev? || options.edge? -%>
-  gem 'web-console', github: "rails/web-console"
+  gem 'web-console', github: 'rails/web-console'
   <%- else -%>
   gem 'web-console', '~> 2.0'
   <%- end -%>
-<%- if spring_install? %>
+<%- end -%>
+<% if spring_install? -%>
   # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
   gem 'spring'
 <% end -%>
-
-  # Adds `Method#source` and `Method#comment` to get the source code of a
-  # method from the console
-  gem 'method_source'
-<% end -%>
 end
+<% end -%>
 
-<% if RUBY_PLATFORM.match(/bccwin|cygwin|emx|mingw|mswin|wince|java/) -%>
 # Windows does not include zoneinfo files, so bundle the tzinfo-data gem
 gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
-<% end -%>
diff --git a/railties/lib/rails/generators/rails/app/templates/README.rdoc b/railties/lib/rails/generators/rails/app/templates/README.md
index dd4e97e22e..55e144da18 100644
--- a/railties/lib/rails/generators/rails/app/templates/README.rdoc
+++ b/railties/lib/rails/generators/rails/app/templates/README.md
@@ -1,4 +1,4 @@
-== README
+## README
 
 This README would normally document whatever steps are necessary to get the
 application up and running.
@@ -22,7 +22,3 @@ Things you may want to cover:
 * Deployment instructions
 
 * ...
-
-
-Please feel free to use a different markup language if you do not plan to run
-<tt>rake doc:app</tt>.
diff --git a/railties/lib/rails/generators/rails/app/templates/app/assets/config/manifest.js.tt b/railties/lib/rails/generators/rails/app/templates/app/assets/config/manifest.js.tt
new file mode 100644
index 0000000000..f80631bac6
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/app/assets/config/manifest.js.tt
@@ -0,0 +1,8 @@
+
+<% unless options.api? -%>
+//= link_tree ../images
+<% end -%>
+<% unless options.skip_javascript -%>
+//= link_directory ../javascripts .js
+<% end -%>
+//= link_directory ../stylesheets .css
diff --git a/railties/lib/rails/generators/rails/app/templates/app/assets/javascripts/application.js.tt b/railties/lib/rails/generators/rails/app/templates/app/assets/javascripts/application.js.tt
index c1a77944e8..c88426ec06 100644
--- a/railties/lib/rails/generators/rails/app/templates/app/assets/javascripts/application.js.tt
+++ b/railties/lib/rails/generators/rails/app/templates/app/assets/javascripts/application.js.tt
@@ -5,9 +5,9 @@
 // or any plugin's vendor/assets/javascripts directory can be referenced here using a relative path.
 //
 // It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
-// compiled file.
+// compiled file. JavaScript code in this file should be added after the last require_* statement.
 //
-// Read Sprockets README (https://github.com/sstephenson/sprockets#sprockets-directives) for details
+// Read Sprockets README (https://github.com/rails/sprockets#sprockets-directives) for details
 // about supported directives.
 //
 <% unless options[:skip_javascript] -%>
diff --git a/railties/lib/rails/generators/rails/app/templates/app/assets/stylesheets/application.css b/railties/lib/rails/generators/rails/app/templates/app/assets/stylesheets/application.css
index f9cd5b3483..0ebd7fe829 100644
--- a/railties/lib/rails/generators/rails/app/templates/app/assets/stylesheets/application.css
+++ b/railties/lib/rails/generators/rails/app/templates/app/assets/stylesheets/application.css
@@ -6,9 +6,9 @@
  * or any plugin's vendor/assets/stylesheets directory can be referenced here using a relative path.
  *
  * You're free to add application-wide styles to this file and they'll appear at the bottom of the
- * compiled file so the styles you add here take precedence over styles defined in any styles
- * defined in the other CSS/SCSS files in this directory. It is generally better to create a new
- * file per style scope.
+ * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
+ * files in this directory. Styles in this file should be added after the last require_* statement.
+ * It is generally better to create a new file per style scope.
  *
  *= require_tree .
  *= require_self
diff --git a/railties/lib/rails/generators/rails/app/templates/app/controllers/application_controller.rb.tt b/railties/lib/rails/generators/rails/app/templates/app/controllers/application_controller.rb.tt
index d83690e1b9..f726fd6305 100644
--- a/railties/lib/rails/generators/rails/app/templates/app/controllers/application_controller.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/app/controllers/application_controller.rb.tt
@@ -1,5 +1,7 @@
-class ApplicationController < ActionController::Base
+class ApplicationController < ActionController::<%= options[:api] ? "API" : "Base" %>
+<%- unless options[:api] -%>
   # Prevent CSRF attacks by raising an exception.
   # For APIs, you may want to use :null_session instead.
   protect_from_forgery with: :exception
+<%- end -%>
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/app/jobs/application_job.rb b/railties/lib/rails/generators/rails/app/templates/app/jobs/application_job.rb
new file mode 100644
index 0000000000..a009ace51c
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/app/jobs/application_job.rb
@@ -0,0 +1,2 @@
+class ApplicationJob < ActiveJob::Base
+end
diff --git a/railties/lib/rails/generators/rails/app/templates/bin/setup b/railties/lib/rails/generators/rails/app/templates/bin/setup
index eee810be30..0c8b179827 100644
--- a/railties/lib/rails/generators/rails/app/templates/bin/setup
+++ b/railties/lib/rails/generators/rails/app/templates/bin/setup
@@ -5,13 +5,17 @@ include FileUtils
 # path to your application root.
 APP_ROOT = Pathname.new File.expand_path('../../', __FILE__)
 
+def system!(*args)
+  system(*args) || abort("\n== Command #{args} failed ==")
+end
+
 chdir APP_ROOT do
   # This script is a starting point to setup your application.
   # Add necessary setup steps to this file.
 
   puts '== Installing dependencies =='
-  system 'gem install bundler --conservative'
-  system('bundle check') or system('bundle install')
+  system! 'gem install bundler --conservative'
+  system('bundle check') or system!('bundle install')
 
   # puts "\n== Copying sample files =="
   # unless File.exist?('config/database.yml')
@@ -19,12 +23,11 @@ chdir APP_ROOT do
   # end
 
   puts "\n== Preparing database =="
-  system 'ruby bin/rake db:setup'
+  system! 'ruby bin/rake db:setup'
 
   puts "\n== Removing old logs and tempfiles =="
-  rm_f Dir.glob('log/*')
-  rm_rf 'tmp/cache'
+  system! 'ruby bin/rake log:clear tmp:clear'
 
   puts "\n== Restarting application server =="
-  touch 'tmp/restart.txt'
+  system! 'ruby bin/rake restart'
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/bin/update b/railties/lib/rails/generators/rails/app/templates/bin/update
new file mode 100644
index 0000000000..9830e6b29a
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/bin/update
@@ -0,0 +1,28 @@
+require 'pathname'
+require 'fileutils'
+include FileUtils
+
+# path to your application root.
+APP_ROOT = Pathname.new File.expand_path('../../', __FILE__)
+
+def system!(*args)
+  system(*args) || abort("\n== Command #{args} failed ==")
+end
+
+chdir APP_ROOT do
+  # This script is a way to update your development environment automatically.
+  # Add necessary update steps to this file.
+
+  puts '== Installing dependencies =='
+  system! 'gem install bundler --conservative'
+  system 'bundle check' or system! 'bundle install'
+
+  puts "\n== Updating database =="
+  system! 'bin/rake db:migrate'
+
+  puts "\n== Removing old logs and tempfiles =="
+  system! 'bin/rake log:clear tmp:clear'
+
+  puts "\n== Restarting application server =="
+  system! 'bin/rake restart'
+end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/application.rb b/railties/lib/rails/generators/rails/app/templates/config/application.rb
index 20ee229e97..ddd0fcade1 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/application.rb
+++ b/railties/lib/rails/generators/rails/app/templates/config/application.rb
@@ -12,7 +12,7 @@ require "action_controller/railtie"
 <%= comment_if :skip_action_mailer %>require "action_mailer/railtie"
 require "action_view/railtie"
 <%= comment_if :skip_sprockets %>require "sprockets/railtie"
-<%= comment_if :skip_test_unit %>require "rails/test_unit/railtie"
+<%= comment_if :skip_test %>require "rails/test_unit/railtie"
 <% end -%>
 
 # Require the gems listed in Gemfile, including any gems
@@ -26,11 +26,18 @@ module <%= app_const_base %>
     # -- all .rb files in that directory are automatically loaded.
 
     # Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
-    # Run "rake -D time" for a list of tasks for finding time zone names. Default is UTC.
+    # Run "rake time:zones:all" for a time zone names list. Default is UTC.
     # config.time_zone = 'Central Time (US & Canada)'
 
     # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
     # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
     # config.i18n.default_locale = :de
+<%- if options[:api] -%>
+
+    # Only loads a smaller set of middleware suitable for API only apps.
+    # Middleware like session, flash, cookies can be added back manually.
+    # Skip views, helpers and assets when generating a new resource.
+    config.api_only = true
+<%- end -%>
   end
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcmysql.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcmysql.yml
index acb93939e1..5ca549a8c8 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcmysql.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcmysql.yml
@@ -7,7 +7,7 @@
 # gem 'activerecord-jdbcmysql-adapter'
 #
 # And be sure to use new-style password hashing:
-#   http://dev.mysql.com/doc/refman/5.0/en/old-client.html
+#   http://dev.mysql.com/doc/refman/5.7/en/old-client.html
 #
 default: &default
   adapter: mysql
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/mysql.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/mysql.yml
index 596c916573..119c2fe2c3 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/mysql.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/mysql.yml
@@ -7,7 +7,7 @@
 #   gem 'mysql2'
 #
 # And be sure to use new-style password hashing:
-#   http://dev.mysql.com/doc/refman/5.0/en/old-client.html
+#   http://dev.mysql.com/doc/refman/5.7/en/old-client.html
 #
 default: &default
   adapter: mysql2
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
index ecb5d4170f..e29f0bacaa 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
@@ -9,9 +9,19 @@ Rails.application.configure do
   # Do not eager load code on boot.
   config.eager_load = false
 
-  # Show full error reports and disable caching.
+  # Show full error reports.
   config.consider_all_requests_local       = true
-  config.action_controller.perform_caching = false
+
+  # Enable/disable caching. By default caching is disabled.
+  if Rails.root.join('tmp/caching-dev.txt').exist?
+    config.action_controller.perform_caching = true
+    config.static_cache_control = "public, max-age=172800"
+    config.cache_store = :memory_store
+  else
+    config.action_controller.perform_caching = false
+    config.cache_store = :null_store
+  end
+
   <%- unless options.skip_action_mailer? -%>
 
   # Don't care if the mailer can't send.
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
index 75666d20c5..0297ab75f6 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
@@ -48,10 +48,11 @@ Rails.application.configure do
   config.log_level = :debug
 
   # Prepend all log lines with the following tags.
-  # config.log_tags = [ :subdomain, :uuid ]
+  # config.log_tags = [ :subdomain, :request_id ]
 
   # Use a different logger for distributed setups.
-  # config.logger = ActiveSupport::TaggedLogging.new(SyslogLogger.new)
+  # require 'syslog/logger'
+  # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name')
 
   # Use a different cache store in production.
   # config.cache_store = :mem_cache_store
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
index 0306deb18c..5165100c22 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
@@ -13,8 +13,10 @@ Rails.application.configure do
   config.eager_load = false
 
   # Configure static file server for tests with Cache-Control for performance.
-  config.serve_static_files   = true
-  config.static_cache_control = 'public, max-age=3600'
+  config.serve_static_files         = true
+  config.public_file_server.headers = {
+    'Cache-Control' => 'public, max-age=3600'
+  }
 
   # Show full error reports and disable caching.
   config.consider_all_requests_local       = true
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/active_record_belongs_to_required_by_default.rb b/railties/lib/rails/generators/rails/app/templates/config/initializers/active_record_belongs_to_required_by_default.rb
new file mode 100644
index 0000000000..30c4f89792
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/active_record_belongs_to_required_by_default.rb
@@ -0,0 +1,4 @@
+# Be sure to restart your server when you modify this file.
+
+# Require `belongs_to` associations by default.
+Rails.application.config.active_record.belongs_to_required_by_default = true
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/application_controller_renderer.rb b/railties/lib/rails/generators/rails/app/templates/config/initializers/application_controller_renderer.rb
new file mode 100644
index 0000000000..ea930f54da
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/application_controller_renderer.rb
@@ -0,0 +1,6 @@
+## Change renderer defaults here.
+#
+# ApplicationController.renderer.defaults.merge!(
+#   http_host: 'example.org',
+#   https: false
+# )
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/callback_terminator.rb b/railties/lib/rails/generators/rails/app/templates/config/initializers/callback_terminator.rb
index e63022da91..a70a1b9cde 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/callback_terminator.rb
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/callback_terminator.rb
@@ -1,4 +1,4 @@
 # Be sure to restart your server when you modify this file.
 
 # Do not halt callback chains when a callback returns false.
-Rails.application.config.active_support.halt_callback_chains_on_return_false = false
+ActiveSupport.halt_callback_chains_on_return_false = false
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/cors.rb b/railties/lib/rails/generators/rails/app/templates/config/initializers/cors.rb
new file mode 100644
index 0000000000..9fca213a04
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/cors.rb
@@ -0,0 +1,14 @@
+# Avoid CORS issues when API is called from the frontend app
+# Handle Cross-Origin Resource Sharing (CORS) in order to accept cross-origin AJAX requests
+
+# Read more: https://github.com/cyu/rack-cors
+
+# Rails.application.config.middleware.insert_before 0, Rack::Cors do
+#   allow do
+#     origins 'example.com'
+#
+#     resource '*',
+#       headers: :any,
+#       methods: [:get, :post, :put, :patch, :delete, :options, :head]
+#   end
+# end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt
index f2110c2c70..cadc85cfac 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt
@@ -5,12 +5,12 @@
 
 # Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array.
 ActiveSupport.on_load(:action_controller) do
-  wrap_parameters format: [:json] if respond_to?(:wrap_parameters)
+  wrap_parameters format: [:json]
 end
 <%- unless options.skip_active_record? -%>
 
 # To enable root element in JSON for ActiveRecord objects.
 # ActiveSupport.on_load(:active_record) do
-#  self.include_root_in_json = true
+#   self.include_root_in_json = true
 # end
 <%- end -%>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/routes.rb b/railties/lib/rails/generators/rails/app/templates/config/routes.rb
index 3f66539d54..787824f888 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/routes.rb
+++ b/railties/lib/rails/generators/rails/app/templates/config/routes.rb
@@ -1,56 +1,3 @@
 Rails.application.routes.draw do
-  # The priority is based upon order of creation: first created -> highest priority.
-  # See how all your routes lay out with "rake routes".
-
-  # You can have the root of your site routed with "root"
-  # root 'welcome#index'
-
-  # Example of regular route:
-  #   get 'products/:id' => 'catalog#view'
-
-  # Example of named route that can be invoked with purchase_url(id: product.id)
-  #   get 'products/:id/purchase' => 'catalog#purchase', as: :purchase
-
-  # Example resource route (maps HTTP verbs to controller actions automatically):
-  #   resources :products
-
-  # Example resource route with options:
-  #   resources :products do
-  #     member do
-  #       get 'short'
-  #       post 'toggle'
-  #     end
-  #
-  #     collection do
-  #       get 'sold'
-  #     end
-  #   end
-
-  # Example resource route with sub-resources:
-  #   resources :products do
-  #     resources :comments, :sales
-  #     resource :seller
-  #   end
-
-  # Example resource route with more complex sub-resources:
-  #   resources :products do
-  #     resources :comments
-  #     resources :sales do
-  #       get 'recent', on: :collection
-  #     end
-  #   end
-
-  # Example resource route with concerns:
-  #   concern :toggleable do
-  #     post 'toggle'
-  #   end
-  #   resources :posts, concerns: :toggleable
-  #   resources :photos, concerns: :toggleable
-
-  # Example resource route within a namespace:
-  #   namespace :admin do
-  #     # Directs /admin/products/* to Admin::ProductsController
-  #     # (app/controllers/admin/products_controller.rb)
-  #     resources :products
-  #   end
+  # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/gitignore b/railties/lib/rails/generators/rails/app/templates/gitignore
index 7c6f2098b8..1b8cf8a9fa 100644
--- a/railties/lib/rails/generators/rails/app/templates/gitignore
+++ b/railties/lib/rails/generators/rails/app/templates/gitignore
@@ -15,5 +15,8 @@
 <% end -%>
 # Ignore all logfiles and tempfiles.
 /log/*
+/tmp/*
+<% if keeps? -%>
 !/log/.keep
-/tmp
+!/tmp/.keep
+<% end -%>
diff --git a/railties/lib/rails/generators/rails/controller/controller_generator.rb b/railties/lib/rails/generators/rails/controller/controller_generator.rb
index df615c88b5..0a4c509a31 100644
--- a/railties/lib/rails/generators/rails/controller/controller_generator.rb
+++ b/railties/lib/rails/generators/rails/controller/controller_generator.rb
@@ -13,12 +13,14 @@ module Rails
       def add_routes
         unless options[:skip_routes]
           actions.reverse_each do |action|
-            route generate_routing_code(action)
+            # route prepends two spaces onto the front of the string that is passed, this corrects that.
+            route generate_routing_code(action)[2..-1]
           end
         end
       end
 
-      hook_for :template_engine, :test_framework, :helper, :assets
+      hook_for :template_engine, :test_framework
+      hook_for :helper, :assets, hide: true
 
       private
 
@@ -36,12 +38,12 @@ module Rails
           # namespace :foo do
           #   namespace :bar do
           namespace_ladder = regular_class_path.each_with_index.map do |ns, i|
-            indent("namespace :#{ns} do\n", i * 2)
+            indent("  namespace :#{ns} do\n", i * 2)
           end.join
 
           # Create route
           #     get 'baz/index'
-          route = indent(%{get '#{file_name}/#{action}'\n}, depth * 2)
+          route = indent(%{  get '#{file_name}/#{action}'\n}, depth * 2)
 
           # Create `end` ladder
           #   end
diff --git a/railties/lib/rails/generators/rails/model/USAGE b/railties/lib/rails/generators/rails/model/USAGE
index 8c3b63c3b4..11daa5c3cb 100644
--- a/railties/lib/rails/generators/rails/model/USAGE
+++ b/railties/lib/rails/generators/rails/model/USAGE
@@ -22,7 +22,7 @@ Description:
 
     If you pass a namespaced model name (e.g. admin/account or Admin::Account)
     then the generator will create a module with a table_name_prefix method
-    to prefix the model's table name with the module name (e.g. admin_account)
+    to prefix the model's table name with the module name (e.g. admin_accounts)
 
 Available field types:
 
@@ -79,10 +79,15 @@ Available field types:
         `rails generate model product supplier:references{polymorphic}:index`
 
     If you require a `password_digest` string column for use with
-    has_secure_password, you should specify `password:digest`:
+    has_secure_password, you can specify `password:digest`:
 
         `rails generate model user password:digest`
 
+    If you require a `token` string column for use with
+    has_secure_token, you can specify `auth_token:token`:
+
+        `rails generate model user auth_token:token`
+
 Examples:
     `rails generate model account`
 
diff --git a/railties/lib/rails/generators/rails/plugin/plugin_generator.rb b/railties/lib/rails/generators/rails/plugin/plugin_generator.rb
index 1c270dd7d4..eeeef430bb 100644
--- a/railties/lib/rails/generators/rails/plugin/plugin_generator.rb
+++ b/railties/lib/rails/generators/rails/plugin/plugin_generator.rb
@@ -8,7 +8,7 @@ module Rails
   # generator.
   #
   # This allows you to override entire operations, like the creation of the
-  # Gemfile, README, or JavaScript files, without needing to know exactly
+  # Gemfile, \README, or JavaScript files, without needing to know exactly
   # what those operations do so you can create another template action.
   class PluginBuilder
     def rakefile
@@ -17,15 +17,22 @@ module Rails
 
     def app
       if mountable?
-        directory 'app'
-        empty_directory_with_keep_file "app/assets/images/#{name}"
+        if api?
+          directory 'app', exclude_pattern: %r{app/(views|helpers)}
+        else
+          directory 'app'
+          empty_directory_with_keep_file "app/assets/images/#{namespaced_name}"
+        end
       elsif full?
         empty_directory_with_keep_file 'app/models'
         empty_directory_with_keep_file 'app/controllers'
-        empty_directory_with_keep_file 'app/views'
-        empty_directory_with_keep_file 'app/helpers'
         empty_directory_with_keep_file 'app/mailers'
-        empty_directory_with_keep_file "app/assets/images/#{name}"
+
+        unless api?
+          empty_directory_with_keep_file "app/assets/images/#{namespaced_name}"
+          empty_directory_with_keep_file 'app/helpers'
+          empty_directory_with_keep_file 'app/views'
+        end
       end
     end
 
@@ -50,10 +57,10 @@ module Rails
     end
 
     def lib
-      template "lib/%name%.rb"
-      template "lib/tasks/%name%_tasks.rake"
-      template "lib/%name%/version.rb"
-      template "lib/%name%/engine.rb" if engine?
+      template "lib/%namespaced_name%.rb"
+      template "lib/tasks/%namespaced_name%_tasks.rake"
+      template "lib/%namespaced_name%/version.rb"
+      template "lib/%namespaced_name%/engine.rb" if engine?
     end
 
     def config
@@ -62,7 +69,7 @@ module Rails
 
     def test
       template "test/test_helper.rb"
-      template "test/%name%_test.rb"
+      template "test/%namespaced_name%_test.rb"
       append_file "Rakefile", <<-EOF
 #{rakefile_test_tasks}
 
@@ -82,6 +89,7 @@ task default: :test
       opts = (options || {}).slice(*PASSTHROUGH_OPTIONS)
       opts[:force] = force
       opts[:skip_bundle] = true
+      opts[:api] = options.api?
 
       invoke Rails::Generators::AppGenerator,
         [ File.expand_path(dummy_path, destination_root) ], opts
@@ -96,8 +104,9 @@ task default: :test
     end
 
     def test_dummy_assets
-      template "rails/javascripts.js",  "#{dummy_path}/app/assets/javascripts/application.js", force: true
-      template "rails/stylesheets.css", "#{dummy_path}/app/assets/stylesheets/application.css", force: true
+      template "rails/javascripts.js",    "#{dummy_path}/app/assets/javascripts/application.js", force: true
+      template "rails/stylesheets.css",   "#{dummy_path}/app/assets/stylesheets/application.css", force: true
+      template "rails/dummy_manifest.js", "#{dummy_path}/app/assets/config/manifest.js", force: true
     end
 
     def test_dummy_clean
@@ -108,18 +117,22 @@ task default: :test
         remove_file "Gemfile"
         remove_file "lib/tasks"
         remove_file "public/robots.txt"
-        remove_file "README"
+        remove_file "README.md"
         remove_file "test"
         remove_file "vendor"
       end
     end
 
+    def assets_manifest
+      template "rails/engine_manifest.js", "app/assets/config/#{underscored_name}_manifest.js"
+    end
+
     def stylesheets
       if mountable?
         copy_file "rails/stylesheets.css",
-                  "app/assets/stylesheets/#{name}/application.css"
+                  "app/assets/stylesheets/#{namespaced_name}/application.css"
       elsif full?
-        empty_directory_with_keep_file "app/assets/stylesheets/#{name}"
+        empty_directory_with_keep_file "app/assets/stylesheets/#{namespaced_name}"
       end
     end
 
@@ -128,9 +141,9 @@ task default: :test
 
       if mountable?
         template "rails/javascripts.js",
-                 "app/assets/javascripts/#{name}/application.js"
+                 "app/assets/javascripts/#{namespaced_name}/application.js"
       elsif full?
-        empty_directory_with_keep_file "app/assets/javascripts/#{name}"
+        empty_directory_with_keep_file "app/assets/javascripts/#{namespaced_name}"
       end
     end
 
@@ -176,6 +189,9 @@ task default: :test
                                         desc: "If creating plugin in application's directory " +
                                                  "skip adding entry to Gemfile"
 
+      class_option :api,          type: :boolean, default: false,
+                                  desc: "Generate a smaller stack for API application plugins"
+
       def initialize(*args)
         @dummy_path = nil
         super
@@ -209,16 +225,16 @@ task default: :test
         build(:lib)
       end
 
-      def create_public_stylesheets_files
-        build(:stylesheets)
+      def create_assets_manifest_file
+        build(:assets_manifest) if !api? && engine?
       end
 
-      def create_javascript_files
-        build(:javascripts)
+      def create_public_stylesheets_files
+        build(:stylesheets) unless api?
       end
 
-      def create_images_directory
-        build(:images)
+      def create_javascript_files
+        build(:javascripts) unless api?
       end
 
       def create_bin_files
@@ -226,7 +242,7 @@ task default: :test
       end
 
       def create_test_files
-        build(:test) unless options[:skip_test_unit]
+        build(:test) unless options[:skip_test]
       end
 
       def create_test_dummy_files
@@ -256,6 +272,14 @@ task default: :test
         end
       end
 
+      def underscored_name
+        @underscored_name ||= original_name.underscore
+      end
+
+      def namespaced_name
+        @namespaced_name ||= name.gsub('-', '/')
+      end
+
     protected
 
       def app_templates_dir
@@ -294,7 +318,11 @@ task default: :test
       end
 
       def with_dummy_app?
-        options[:skip_test_unit].blank? || options[:dummy_path] != 'test/dummy'
+        options[:skip_test].blank? || options[:dummy_path] != 'test/dummy'
+      end
+
+      def api?
+        options[:api]
       end
 
       def self.banner
@@ -305,6 +333,27 @@ task default: :test
         @original_name ||= File.basename(destination_root)
       end
 
+      def modules
+        @modules ||= namespaced_name.camelize.split("::")
+      end
+
+      def wrap_in_modules(unwrapped_code)
+        unwrapped_code = "#{unwrapped_code}".strip.gsub(/\W$\n/, '')
+        modules.reverse.inject(unwrapped_code) do |content, mod|
+          str = "module #{mod}\n"
+          str += content.lines.map { |line| "  #{line}" }.join
+          str += content.present? ? "\nend" : "end"
+        end
+      end
+
+      def camelized_modules
+        @camelized_modules ||= namespaced_name.camelize
+      end
+
+      def humanized
+        @humanized ||= original_name.underscore.humanize
+      end
+
       def camelized
         @camelized ||= name.gsub(/\W/, '_').squeeze('_').camelize
       end
@@ -328,12 +377,16 @@ task default: :test
       end
 
       def valid_const?
-        if original_name =~ /[^0-9a-zA-Z_]+/
-          raise Error, "Invalid plugin name #{original_name}. Please give a name which use only alphabetic or numeric or \"_\" characters."
+        if original_name =~ /-\d/
+          raise Error, "Invalid plugin name #{original_name}. Please give a name which does not contain a namespace starting with numeric characters."
+        elsif original_name =~ /[^\w-]+/
+          raise Error, "Invalid plugin name #{original_name}. Please give a name which uses only alphabetic, numeric, \"_\" or \"-\" characters."
         elsif camelized =~ /^\d/
           raise Error, "Invalid plugin name #{original_name}. Please give a name which does not start with numbers."
         elsif RESERVED_NAMES.include?(name)
-          raise Error, "Invalid plugin name #{original_name}. Please give a name which does not match one of the reserved rails words."
+          raise Error, "Invalid plugin name #{original_name}. Please give a " \
+                       "name which does not match one of the reserved rails " \
+                       "words: #{RESERVED_NAMES.join(", ")}"
         elsif Object.const_defined?(camelized)
           raise Error, "Invalid plugin name #{original_name}, constant #{camelized} is already in use. Please choose another plugin name."
         end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/%name%.gemspec b/railties/lib/rails/generators/rails/plugin/templates/%name%.gemspec
index 919c349470..f8ece4fe73 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/%name%.gemspec
+++ b/railties/lib/rails/generators/rails/plugin/templates/%name%.gemspec
@@ -1,21 +1,21 @@
 $:.push File.expand_path("../lib", __FILE__)
 
 # Maintain your gem's version:
-require "<%= name %>/version"
+require "<%= namespaced_name %>/version"
 
 # Describe your gem and declare its dependencies:
 Gem::Specification.new do |s|
   s.name        = "<%= name %>"
-  s.version     = <%= camelized %>::VERSION
+  s.version     = <%= camelized_modules %>::VERSION
   s.authors     = ["<%= author %>"]
   s.email       = ["<%= email %>"]
   s.homepage    = "TODO"
-  s.summary     = "TODO: Summary of <%= camelized %>."
-  s.description = "TODO: Description of <%= camelized %>."
+  s.summary     = "TODO: Summary of <%= camelized_modules %>."
+  s.description = "TODO: Description of <%= camelized_modules %>."
   s.license     = "MIT"
 
   s.files = Dir["{app,config,db,lib}/**/*", "MIT-LICENSE", "Rakefile", "README.rdoc"]
-<% unless options.skip_test_unit? -%>
+<% unless options.skip_test? -%>
   s.test_files = Dir["test/**/*"]
 <% end -%>
 
diff --git a/railties/lib/rails/generators/rails/plugin/templates/Gemfile b/railties/lib/rails/generators/rails/plugin/templates/Gemfile
index f325455bac..2c91c6a0ea 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/Gemfile
+++ b/railties/lib/rails/generators/rails/plugin/templates/Gemfile
@@ -41,7 +41,7 @@ end
 # To use a debugger
 # gem 'byebug', group: [:development, :test]
 <% end -%>
-
 <% if RUBY_PLATFORM.match(/bccwin|cygwin|emx|mingw|mswin|wince|java/) -%>
+
 gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
 <% end -%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/README.rdoc b/railties/lib/rails/generators/rails/plugin/templates/README.rdoc
index 301d647731..25983ca5da 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/README.rdoc
+++ b/railties/lib/rails/generators/rails/plugin/templates/README.rdoc
@@ -1,3 +1,3 @@
-= <%= camelized %>
+= <%= camelized_modules %>
 
 This project rocks and uses MIT-LICENSE.
\ No newline at end of file
diff --git a/railties/lib/rails/generators/rails/plugin/templates/Rakefile b/railties/lib/rails/generators/rails/plugin/templates/Rakefile
index c338a0bdb1..bda55bae29 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/Rakefile
+++ b/railties/lib/rails/generators/rails/plugin/templates/Rakefile
@@ -8,7 +8,7 @@ require 'rdoc/task'
 
 RDoc::Task.new(:rdoc) do |rdoc|
   rdoc.rdoc_dir = 'rdoc'
-  rdoc.title    = '<%= camelized %>'
+  rdoc.title    = '<%= camelized_modules %>'
   rdoc.options << '--line-numbers'
   rdoc.rdoc_files.include('README.rdoc')
   rdoc.rdoc_files.include('lib/**/*.rb')
diff --git a/railties/lib/rails/generators/rails/plugin/templates/app/controllers/%name%/application_controller.rb.tt b/railties/lib/rails/generators/rails/plugin/templates/app/controllers/%name%/application_controller.rb.tt
deleted file mode 100644
index 448ad7f989..0000000000
--- a/railties/lib/rails/generators/rails/plugin/templates/app/controllers/%name%/application_controller.rb.tt
+++ /dev/null
@@ -1,4 +0,0 @@
-module <%= camelized %>
-  class ApplicationController < ActionController::Base
-  end
-end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/app/controllers/%namespaced_name%/application_controller.rb.tt b/railties/lib/rails/generators/rails/plugin/templates/app/controllers/%namespaced_name%/application_controller.rb.tt
new file mode 100644
index 0000000000..7fe4e5034d
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/app/controllers/%namespaced_name%/application_controller.rb.tt
@@ -0,0 +1,5 @@
+<%= wrap_in_modules <<-rb.strip_heredoc
+  class ApplicationController < ActionController::#{api? ? "API" : "Base"}
+  end
+rb
+%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/app/helpers/%name%/application_helper.rb.tt b/railties/lib/rails/generators/rails/plugin/templates/app/helpers/%name%/application_helper.rb.tt
deleted file mode 100644
index 40ae9f52c2..0000000000
--- a/railties/lib/rails/generators/rails/plugin/templates/app/helpers/%name%/application_helper.rb.tt
+++ /dev/null
@@ -1,4 +0,0 @@
-module <%= camelized %>
-  module ApplicationHelper
-  end
-end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/app/helpers/%namespaced_name%/application_helper.rb.tt b/railties/lib/rails/generators/rails/plugin/templates/app/helpers/%namespaced_name%/application_helper.rb.tt
new file mode 100644
index 0000000000..25d692732d
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/app/helpers/%namespaced_name%/application_helper.rb.tt
@@ -0,0 +1,5 @@
+<%= wrap_in_modules <<-rb.strip_heredoc
+  module ApplicationHelper
+  end
+rb
+%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/app/jobs/%namespaced_name%/application_job.rb.tt b/railties/lib/rails/generators/rails/plugin/templates/app/jobs/%namespaced_name%/application_job.rb.tt
new file mode 100644
index 0000000000..bad1ff2d16
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/app/jobs/%namespaced_name%/application_job.rb.tt
@@ -0,0 +1,5 @@
+<%= wrap_in_modules <<-rb.strip_heredoc
+  class ApplicationJob < ActiveJob::Base
+  end
+rb
+%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/app/views/layouts/%name%/application.html.erb.tt b/railties/lib/rails/generators/rails/plugin/templates/app/views/layouts/%name%/application.html.erb.tt
deleted file mode 100644
index 1d380420b4..0000000000
--- a/railties/lib/rails/generators/rails/plugin/templates/app/views/layouts/%name%/application.html.erb.tt
+++ /dev/null
@@ -1,14 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <title><%= camelized %></title>
-  <%%= stylesheet_link_tag    "<%= name %>/application", media: "all" %>
-  <%%= javascript_include_tag "<%= name %>/application" %>
-  <%%= csrf_meta_tags %>
-</head>
-<body>
-
-<%%= yield %>
-
-</body>
-</html>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/app/views/layouts/%namespaced_name%/application.html.erb.tt b/railties/lib/rails/generators/rails/plugin/templates/app/views/layouts/%namespaced_name%/application.html.erb.tt
new file mode 100644
index 0000000000..6bc480161d
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/app/views/layouts/%namespaced_name%/application.html.erb.tt
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title><%= humanized %></title>
+  <%%= stylesheet_link_tag    "<%= namespaced_name %>/application", media: "all" %>
+  <%%= javascript_include_tag "<%= namespaced_name %>/application" %>
+  <%%= csrf_meta_tags %>
+</head>
+<body>
+
+<%%= yield %>
+
+</body>
+</html>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/bin/rails.tt b/railties/lib/rails/generators/rails/plugin/templates/bin/rails.tt
index c3314d7e68..3edaac35c9 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/bin/rails.tt
+++ b/railties/lib/rails/generators/rails/plugin/templates/bin/rails.tt
@@ -1,7 +1,7 @@
 # This command will automatically be run when you run "rails" with Rails 4 gems installed from the root of your application.
 
 ENGINE_ROOT = File.expand_path('../..', __FILE__)
-ENGINE_PATH = File.expand_path('../../lib/<%= name -%>/engine', __FILE__)
+ENGINE_PATH = File.expand_path('../../lib/<%= namespaced_name -%>/engine', __FILE__)
 
 # Set up gems listed in the Gemfile.
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
diff --git a/railties/lib/rails/generators/rails/plugin/templates/config/routes.rb b/railties/lib/rails/generators/rails/plugin/templates/config/routes.rb
index 8e158d5831..154452bfe5 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/config/routes.rb
+++ b/railties/lib/rails/generators/rails/plugin/templates/config/routes.rb
@@ -1,5 +1,5 @@
 <% if mountable? -%>
-<%= camelized %>::Engine.routes.draw do
+<%= camelized_modules %>::Engine.routes.draw do
 <% else -%>
 Rails.application.routes.draw do
 <% end -%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/gitignore b/railties/lib/rails/generators/rails/plugin/templates/gitignore
index 086d87818a..d524fcbc4e 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/gitignore
+++ b/railties/lib/rails/generators/rails/plugin/templates/gitignore
@@ -1,10 +1,10 @@
 .bundle/
 log/*.log
 pkg/
-<% unless options[:skip_test_unit] && options[:dummy_path] == 'test/dummy' -%>
+<% unless options[:skip_test] && options[:dummy_path] == 'test/dummy' -%>
 <%= dummy_path %>/db/*.sqlite3
 <%= dummy_path %>/db/*.sqlite3-journal
 <%= dummy_path %>/log/*.log
 <%= dummy_path %>/tmp/
 <%= dummy_path %>/.sass-cache
-<% end -%>
\ No newline at end of file
+<% end -%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/lib/%name%.rb b/railties/lib/rails/generators/rails/plugin/templates/lib/%name%.rb
deleted file mode 100644
index 40c074cced..0000000000
--- a/railties/lib/rails/generators/rails/plugin/templates/lib/%name%.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-<% if engine? -%>
-require "<%= name %>/engine"
-
-<% end -%>
-module <%= camelized %>
-end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/lib/%name%/engine.rb b/railties/lib/rails/generators/rails/plugin/templates/lib/%name%/engine.rb
deleted file mode 100644
index 967668fe66..0000000000
--- a/railties/lib/rails/generators/rails/plugin/templates/lib/%name%/engine.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-module <%= camelized %>
-  class Engine < ::Rails::Engine
-<% if mountable? -%>
-    isolate_namespace <%= camelized %>
-<% end -%>
-  end
-end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/lib/%name%/version.rb b/railties/lib/rails/generators/rails/plugin/templates/lib/%name%/version.rb
deleted file mode 100644
index ef07ef2e19..0000000000
--- a/railties/lib/rails/generators/rails/plugin/templates/lib/%name%/version.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-module <%= camelized %>
-  VERSION = "0.0.1"
-end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%.rb b/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%.rb
new file mode 100644
index 0000000000..40b1c4cee7
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%.rb
@@ -0,0 +1,5 @@
+<% if engine? -%>
+require "<%= namespaced_name %>/engine"
+
+<% end -%>
+<%= wrap_in_modules "# Your code goes here..." %>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%/engine.rb b/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%/engine.rb
new file mode 100644
index 0000000000..8938770fc4
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%/engine.rb
@@ -0,0 +1,7 @@
+<%= wrap_in_modules <<-rb.strip_heredoc
+  class Engine < ::Rails::Engine
+  #{mountable? ? '  isolate_namespace ' + camelized_modules : ' '}
+  #{api? ? "  config.generators.api_only = true" : ' '}
+  end
+rb
+%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%/version.rb b/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%/version.rb
new file mode 100644
index 0000000000..b08f4ef9ae
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/lib/%namespaced_name%/version.rb
@@ -0,0 +1 @@
+<%= wrap_in_modules "VERSION = '0.1.0'" %>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/lib/tasks/%name%_tasks.rake b/railties/lib/rails/generators/rails/plugin/templates/lib/tasks/%namespaced_name%_tasks.rake
index 7121f5ae23..88a2c4120f 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/lib/tasks/%name%_tasks.rake
+++ b/railties/lib/rails/generators/rails/plugin/templates/lib/tasks/%namespaced_name%_tasks.rake
@@ -1,4 +1,4 @@
 # desc "Explaining what the task does"
-# task :<%= name %> do
+# task :<%= underscored_name %> do
 #   # Task goes here
 # end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/rails/application.rb b/railties/lib/rails/generators/rails/plugin/templates/rails/application.rb
index 3a9a7e5437..b1038c839e 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/rails/application.rb
+++ b/railties/lib/rails/generators/rails/plugin/templates/rails/application.rb
@@ -9,10 +9,10 @@ require "action_controller/railtie"
 <%= comment_if :skip_action_mailer %>require "action_mailer/railtie"
 require "action_view/railtie"
 <%= comment_if :skip_sprockets %>require "sprockets/railtie"
-<%= comment_if :skip_test_unit %>require "rails/test_unit/railtie"
+<%= comment_if :skip_test %>require "rails/test_unit/railtie"
 <% end -%>
 
 Bundler.require(*Rails.groups)
-require "<%= name %>"
+require "<%= namespaced_name %>"
 
 <%= application_definition %>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/rails/dummy_manifest.js b/railties/lib/rails/generators/rails/plugin/templates/rails/dummy_manifest.js
new file mode 100644
index 0000000000..8d21b2b6fb
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/rails/dummy_manifest.js
@@ -0,0 +1,11 @@
+
+<% unless api? -%>
+//= link_tree ../images
+<% end -%>
+<% unless options.skip_javascript -%>
+//= link_directory ../javascripts .js
+<% end -%>
+//= link_directory ../stylesheets .css
+<% if mountable? && !api? -%>
+//= link <%= underscored_name %>_manifest.js
+<% end -%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/rails/engine_manifest.js b/railties/lib/rails/generators/rails/plugin/templates/rails/engine_manifest.js
new file mode 100644
index 0000000000..2f23844f5e
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/rails/engine_manifest.js
@@ -0,0 +1,6 @@
+<% if mountable? -%>
+<% if !options.skip_javascript -%>
+//= link_directory ../javascripts/<%= namespaced_name %> .js
+<% end -%>
+//= link_directory ../stylesheets/<%= namespaced_name %> .css
+<% end -%>
diff --git a/railties/lib/rails/generators/rails/plugin/templates/rails/javascripts.js b/railties/lib/rails/generators/rails/plugin/templates/rails/javascripts.js
index c28e5badc6..e54c6461cc 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/rails/javascripts.js
+++ b/railties/lib/rails/generators/rails/plugin/templates/rails/javascripts.js
@@ -5,9 +5,9 @@
 // or any plugin's vendor/assets/javascripts directory can be referenced here using a relative path.
 //
 // It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
-// compiled file.
+// compiled file. JavaScript code in this file should be added after the last require_* statement.
 //
-// Read Sprockets README (https://github.com/sstephenson/sprockets#sprockets-directives) for details
+// Read Sprockets README (https://github.com/rails/sprockets#sprockets-directives) for details
 // about supported directives.
 //
 //= require_tree .
diff --git a/railties/lib/rails/generators/rails/plugin/templates/rails/routes.rb b/railties/lib/rails/generators/rails/plugin/templates/rails/routes.rb
index 730ee31c3d..673de44108 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/rails/routes.rb
+++ b/railties/lib/rails/generators/rails/plugin/templates/rails/routes.rb
@@ -1,4 +1,4 @@
 Rails.application.routes.draw do
 
-  mount <%= camelized %>::Engine => "/<%= name %>"
+  mount <%= camelized_modules %>::Engine => "/<%= name %>"
 end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/rails/stylesheets.css b/railties/lib/rails/generators/rails/plugin/templates/rails/stylesheets.css
index f9cd5b3483..0ebd7fe829 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/rails/stylesheets.css
+++ b/railties/lib/rails/generators/rails/plugin/templates/rails/stylesheets.css
@@ -6,9 +6,9 @@
  * or any plugin's vendor/assets/stylesheets directory can be referenced here using a relative path.
  *
  * You're free to add application-wide styles to this file and they'll appear at the bottom of the
- * compiled file so the styles you add here take precedence over styles defined in any styles
- * defined in the other CSS/SCSS files in this directory. It is generally better to create a new
- * file per style scope.
+ * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
+ * files in this directory. Styles in this file should be added after the last require_* statement.
+ * It is generally better to create a new file per style scope.
  *
  *= require_tree .
  *= require_self
diff --git a/railties/lib/rails/generators/rails/plugin/templates/test/%name%_test.rb b/railties/lib/rails/generators/rails/plugin/templates/test/%name%_test.rb
deleted file mode 100644
index 0a8bbd4aaf..0000000000
--- a/railties/lib/rails/generators/rails/plugin/templates/test/%name%_test.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require 'test_helper'
-
-class <%= camelized %>Test < ActiveSupport::TestCase
-  test "truth" do
-    assert_kind_of Module, <%= camelized %>
-  end
-end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/test/%namespaced_name%_test.rb b/railties/lib/rails/generators/rails/plugin/templates/test/%namespaced_name%_test.rb
new file mode 100644
index 0000000000..1ee05d7871
--- /dev/null
+++ b/railties/lib/rails/generators/rails/plugin/templates/test/%namespaced_name%_test.rb
@@ -0,0 +1,7 @@
+require 'test_helper'
+
+class <%= camelized_modules %>::Test < ActiveSupport::TestCase
+  test "truth" do
+    assert_kind_of Module, <%= camelized_modules %>
+  end
+end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/test/integration/navigation_test.rb b/railties/lib/rails/generators/rails/plugin/templates/test/integration/navigation_test.rb
index 824caecb24..f5d1ec2046 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/test/integration/navigation_test.rb
+++ b/railties/lib/rails/generators/rails/plugin/templates/test/integration/navigation_test.rb
@@ -1,10 +1,6 @@
 require 'test_helper'
 
 class NavigationTest < ActionDispatch::IntegrationTest
-<% unless options[:skip_active_record] -%>
-  fixtures :all
-<% end -%>
-
   # test "the truth" do
   #   assert true
   # end
diff --git a/railties/lib/rails/generators/rails/plugin/templates/test/test_helper.rb b/railties/lib/rails/generators/rails/plugin/templates/test/test_helper.rb
index bf3da1fc4d..f315144723 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/test/test_helper.rb
+++ b/railties/lib/rails/generators/rails/plugin/templates/test/test_helper.rb
@@ -14,10 +14,10 @@ require "rails/test_help"
 # to be shown.
 Minitest.backtrace_filter = Minitest::BacktraceFilter.new
 
-# Load support files
-Dir["#{File.dirname(__FILE__)}/support/**/*.rb"].each { |f| require f }
-
 # Load fixtures from the engine
 if ActiveSupport::TestCase.respond_to?(:fixture_path=)
   ActiveSupport::TestCase.fixture_path = File.expand_path("../fixtures", __FILE__)
+  ActionDispatch::IntegrationTest.fixture_path = ActiveSupport::TestCase.fixture_path
+  ActiveSupport::TestCase.file_fixture_path = ActiveSupport::TestCase.fixture_path + "/files"
+  ActiveSupport::TestCase.fixtures :all
 end
diff --git a/railties/lib/rails/generators/rails/resource/resource_generator.rb b/railties/lib/rails/generators/rails/resource/resource_generator.rb
index 8014feb75f..3acf21df13 100644
--- a/railties/lib/rails/generators/rails/resource/resource_generator.rb
+++ b/railties/lib/rails/generators/rails/resource/resource_generator.rb
@@ -1,6 +1,5 @@
 require 'rails/generators/resource_helpers'
 require 'rails/generators/rails/model/model_generator'
-require 'active_support/core_ext/object/blank'
 
 module Rails
   module Generators
diff --git a/railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb b/railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb
index e4a2bc2b0f..42705107ae 100644
--- a/railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb
+++ b/railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb
@@ -1,7 +1,6 @@
 module Rails
   module Generators
     class ResourceRouteGenerator < NamedBase # :nodoc:
-
       # Properly nests namespaces passed into a generator
       #
       #   $ rails generate resource admin/users/products
@@ -29,8 +28,10 @@ module Rails
           write("end", route_length - index)
         end
 
-        # route prepends two spaces onto the front of the string that is passed, this corrects that
-        route route_string[2..-1]
+        # route prepends two spaces onto the front of the string that is passed, this corrects that.
+        # Also it adds a \n to the end of each line, as route already adds that
+        # we need to correct that too.
+        route route_string[2..-2]
       end
 
       private
diff --git a/railties/lib/rails/generators/rails/scaffold/USAGE b/railties/lib/rails/generators/rails/scaffold/USAGE
index 1b2a944103..d2e495758d 100644
--- a/railties/lib/rails/generators/rails/scaffold/USAGE
+++ b/railties/lib/rails/generators/rails/scaffold/USAGE
@@ -36,6 +36,6 @@ Description:
 
 Examples:
     `rails generate scaffold post`
-    `rails generate scaffold post title body:text published:boolean`
+    `rails generate scaffold post title:string body:text published:boolean`
     `rails generate scaffold purchase amount:decimal tracking_id:integer:uniq`
     `rails generate scaffold user email:uniq password:digest`
diff --git a/railties/lib/rails/generators/rails/scaffold/scaffold_generator.rb b/railties/lib/rails/generators/rails/scaffold/scaffold_generator.rb
index e89789e72b..17c32bfdb3 100644
--- a/railties/lib/rails/generators/rails/scaffold/scaffold_generator.rb
+++ b/railties/lib/rails/generators/rails/scaffold/scaffold_generator.rb
@@ -10,10 +10,11 @@ module Rails
       class_option :stylesheet_engine, desc: "Engine for Stylesheets"
       class_option :assets, type: :boolean
       class_option :resource_route, type: :boolean
+      class_option :scaffold_stylesheet, type: :boolean
 
       def handle_skip
         @options = @options.merge(stylesheets: false) unless options[:assets]
-        @options = @options.merge(stylesheet_engine: false) unless options[:stylesheets]
+        @options = @options.merge(stylesheet_engine: false) unless options[:stylesheets] && options[:scaffold_stylesheet]
       end
 
       hook_for :scaffold_controller, required: true
diff --git a/railties/lib/rails/generators/rails/scaffold/templates/scaffold.css b/railties/lib/rails/generators/rails/scaffold/templates/scaffold.css
index 1ae7000299..b7818883d1 100644
--- a/railties/lib/rails/generators/rails/scaffold/templates/scaffold.css
+++ b/railties/lib/rails/generators/rails/scaffold/templates/scaffold.css
@@ -1,9 +1,13 @@
-body { background-color: #fff; color: #333; }
+body {
+  background-color: #fff;
+  color: #333;
+}
 
 body, p, ol, ul, td {
   font-family: verdana, arial, helvetica, sans-serif;
-  font-size:   13px;
+  font-size: 13px;
   line-height: 18px;
+  margin: 33px;
 }
 
 pre {
@@ -12,11 +16,31 @@ pre {
   font-size: 11px;
 }
 
-a { color: #000; }
-a:visited { color: #666; }
-a:hover { color: #fff; background-color:#000; }
+a {
+  color: #000;
+}
+
+a:visited {
+  color: #666;
+}
+
+a:hover {
+  color: #fff;
+  background-color: #000;
+}
+
+th {
+  padding-bottom: 5px;
+}
+
+td {
+  padding-bottom: 7px;
+  padding-left: 5px;
+  padding-right: 5px;
+}
 
-div.field, div.actions {
+div.field,
+div.actions {
   margin-bottom: 10px;
 }
 
@@ -45,7 +69,7 @@ div.field, div.actions {
   padding: 5px 5px 5px 15px;
   font-size: 12px;
   margin: -7px;
-  margin-bottom: 0px;
+  margin-bottom: 0;
   background-color: #c00;
   color: #fff;
 }
diff --git a/railties/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb b/railties/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb
index c01b82884d..d0b8cad896 100644
--- a/railties/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb
+++ b/railties/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb
@@ -10,11 +10,14 @@ module Rails
       class_option :helper, type: :boolean
       class_option :orm, banner: "NAME", type: :string, required: true,
                          desc: "ORM to generate the controller for"
+      class_option :api, type: :boolean,
+                         desc: "Generates API controller"
 
       argument :attributes, type: :array, default: [], banner: "field:type field:type"
 
       def create_controller_files
-        template "controller.rb", File.join('app/controllers', controller_class_path, "#{controller_file_name}_controller.rb")
+        template_file = options.api? ? "api_controller.rb" : "controller.rb"
+        template template_file, File.join('app/controllers', controller_class_path, "#{controller_file_name}_controller.rb")
       end
 
       hook_for :template_engine, :test_framework, as: :scaffold
diff --git a/railties/lib/rails/generators/rails/scaffold_controller/templates/api_controller.rb b/railties/lib/rails/generators/rails/scaffold_controller/templates/api_controller.rb
new file mode 100644
index 0000000000..bc3c9b3f6b
--- /dev/null
+++ b/railties/lib/rails/generators/rails/scaffold_controller/templates/api_controller.rb
@@ -0,0 +1,61 @@
+<% if namespaced? -%>
+require_dependency "<%= namespaced_file_path %>/application_controller"
+
+<% end -%>
+<% module_namespacing do -%>
+class <%= controller_class_name %>Controller < ApplicationController
+  before_action :set_<%= singular_table_name %>, only: [:show, :update, :destroy]
+
+  # GET <%= route_url %>
+  def index
+    @<%= plural_table_name %> = <%= orm_class.all(class_name) %>
+
+    render json: <%= "@#{plural_table_name}" %>
+  end
+
+  # GET <%= route_url %>/1
+  def show
+    render json: <%= "@#{singular_table_name}" %>
+  end
+
+  # POST <%= route_url %>
+  def create
+    @<%= singular_table_name %> = <%= orm_class.build(class_name, "#{singular_table_name}_params") %>
+
+    if @<%= orm_instance.save %>
+      render json: <%= "@#{singular_table_name}" %>, status: :created, location: <%= "@#{singular_table_name}" %>
+    else
+      render json: <%= "@#{orm_instance.errors}" %>, status: :unprocessable_entity
+    end
+  end
+
+  # PATCH/PUT <%= route_url %>/1
+  def update
+    if @<%= orm_instance.update("#{singular_table_name}_params") %>
+      render json: <%= "@#{singular_table_name}" %>
+    else
+      render json: <%= "@#{orm_instance.errors}" %>, status: :unprocessable_entity
+    end
+  end
+
+  # DELETE <%= route_url %>/1
+  def destroy
+    @<%= orm_instance.destroy %>
+  end
+
+  private
+    # Use callbacks to share common setup or constraints between actions.
+    def set_<%= singular_table_name %>
+      @<%= singular_table_name %> = <%= orm_class.find(class_name, "params[:id]") %>
+    end
+
+    # Only allow a trusted parameter "white list" through.
+    def <%= "#{singular_table_name}_params" %>
+      <%- if attributes_names.empty? -%>
+      params[:<%= singular_table_name %>]
+      <%- else -%>
+      params.require(:<%= singular_table_name %>).permit(<%= attributes_names.map { |name| ":#{name}" }.join(', ') %>)
+      <%- end -%>
+    end
+end
+<% end -%>
diff --git a/railties/lib/rails/generators/rails/scaffold_controller/templates/controller.rb b/railties/lib/rails/generators/rails/scaffold_controller/templates/controller.rb
index 2c3b04043f..f73e9a96ba 100644
--- a/railties/lib/rails/generators/rails/scaffold_controller/templates/controller.rb
+++ b/railties/lib/rails/generators/rails/scaffold_controller/templates/controller.rb
@@ -1,5 +1,5 @@
 <% if namespaced? -%>
-require_dependency "<%= namespaced_file_path %>/application_controller"
+require_dependency "<%= namespaced_path %>/application_controller"
 
 <% end -%>
 <% module_namespacing do -%>
diff --git a/railties/lib/rails/generators/resource_helpers.rb b/railties/lib/rails/generators/resource_helpers.rb
index 3f84d76ae0..9c2037783e 100644
--- a/railties/lib/rails/generators/resource_helpers.rb
+++ b/railties/lib/rails/generators/resource_helpers.rb
@@ -8,7 +8,7 @@ module Rails
     module ResourceHelpers # :nodoc:
 
       def self.included(base) #:nodoc:
-        base.send :include, Rails::Generators::ModelHelpers
+        base.include(Rails::Generators::ModelHelpers)
         base.class_option :model_name, type: :string, desc: "ModelName to be used"
       end
 
diff --git a/railties/lib/rails/generators/test_unit/controller/templates/functional_test.rb b/railties/lib/rails/generators/test_unit/controller/templates/functional_test.rb
index 509bd60564..5a8a3ca5e0 100644
--- a/railties/lib/rails/generators/test_unit/controller/templates/functional_test.rb
+++ b/railties/lib/rails/generators/test_unit/controller/templates/functional_test.rb
@@ -2,6 +2,12 @@ require 'test_helper'
 
 <% module_namespacing do -%>
 class <%= class_name %>ControllerTest < ActionController::TestCase
+<% if mountable_engine? -%>
+  setup do
+    @routes = Engine.routes
+  end
+
+<% end -%>
 <% if actions.empty? -%>
   # test "the truth" do
   #   assert true
diff --git a/railties/lib/rails/generators/test_unit/mailer/mailer_generator.rb b/railties/lib/rails/generators/test_unit/mailer/mailer_generator.rb
index ba131da79d..343c8a3949 100644
--- a/railties/lib/rails/generators/test_unit/mailer/mailer_generator.rb
+++ b/railties/lib/rails/generators/test_unit/mailer/mailer_generator.rb
@@ -16,6 +16,11 @@ module TestUnit # :nodoc:
       def create_preview_files
         template "preview.rb", File.join('test/mailers/previews', class_path, "#{file_name}_mailer_preview.rb")
       end
+
+      protected
+        def file_name
+          @_file_name ||= super.gsub(/\_mailer/i, '')
+        end
     end
   end
 end
diff --git a/railties/lib/rails/generators/test_unit/mailer/templates/functional_test.rb b/railties/lib/rails/generators/test_unit/mailer/templates/functional_test.rb
index 3cee517db3..a2f2d30de5 100644
--- a/railties/lib/rails/generators/test_unit/mailer/templates/functional_test.rb
+++ b/railties/lib/rails/generators/test_unit/mailer/templates/functional_test.rb
@@ -4,7 +4,7 @@ require 'test_helper'
 class <%= class_name %>MailerTest < ActionMailer::TestCase
 <% actions.each do |action| -%>
   test "<%= action %>" do
-    mail = <%= class_name %>.<%= action %>
+    mail = <%= class_name %>Mailer.<%= action %>
     assert_equal <%= action.to_s.humanize.inspect %>, mail.subject
     assert_equal ["to@example.org"], mail.to
     assert_equal ["from@example.com"], mail.from
diff --git a/railties/lib/rails/generators/test_unit/mailer/templates/preview.rb b/railties/lib/rails/generators/test_unit/mailer/templates/preview.rb
index 6b85764a66..b063cbc47b 100644
--- a/railties/lib/rails/generators/test_unit/mailer/templates/preview.rb
+++ b/railties/lib/rails/generators/test_unit/mailer/templates/preview.rb
@@ -1,9 +1,9 @@
 <% module_namespacing do -%>
-# Preview all emails at http://localhost:3000/rails/mailers/<%= file_path %>
+# Preview all emails at http://localhost:3000/rails/mailers/<%= file_path %>_mailer
 class <%= class_name %>MailerPreview < ActionMailer::Preview
 <% actions.each do |action| -%>
 
-  # Preview this email at http://localhost:3000/rails/mailers/<%= file_path %>/<%= action %>
+  # Preview this email at http://localhost:3000/rails/mailers/<%= file_path %>_mailer/<%= action %>
   def <%= action %>
     <%= class_name %>Mailer.<%= action %>
   end
diff --git a/railties/lib/rails/generators/test_unit/model/model_generator.rb b/railties/lib/rails/generators/test_unit/model/model_generator.rb
index 2826a3ffa1..086588750e 100644
--- a/railties/lib/rails/generators/test_unit/model/model_generator.rb
+++ b/railties/lib/rails/generators/test_unit/model/model_generator.rb
@@ -19,7 +19,7 @@ module TestUnit # :nodoc:
 
       def create_fixture_file
         if options[:fixture] && options[:fixture_replacement].nil?
-          template 'fixtures.yml', File.join('test/fixtures', class_path, "#{plural_file_name}.yml")
+          template 'fixtures.yml', File.join('test/fixtures', class_path, "#{fixture_file_name}.yml")
         end
       end
 
diff --git a/railties/lib/rails/generators/test_unit/scaffold/scaffold_generator.rb b/railties/lib/rails/generators/test_unit/scaffold/scaffold_generator.rb
index 2e1f55f2a6..0171da7cc7 100644
--- a/railties/lib/rails/generators/test_unit/scaffold/scaffold_generator.rb
+++ b/railties/lib/rails/generators/test_unit/scaffold/scaffold_generator.rb
@@ -8,13 +8,26 @@ module TestUnit # :nodoc:
 
       check_class_collision suffix: "ControllerTest"
 
+      class_option :api, type: :boolean,
+                         desc: "Generates API functional tests"
+
       argument :attributes, type: :array, default: [], banner: "field:type field:type"
 
       def create_test_files
-        template "functional_test.rb",
+        template_file = options.api? ? "api_functional_test.rb" : "functional_test.rb"
+        template template_file,
                  File.join("test/controllers", controller_class_path, "#{controller_file_name}_controller_test.rb")
       end
 
+      def fixture_name
+        @fixture_name ||=
+          if mountable_engine?
+            "%s_%s" % [namespaced_path, table_name]
+          else
+            table_name
+          end
+      end
+
       private
 
         def attributes_hash
diff --git a/railties/lib/rails/generators/test_unit/scaffold/templates/api_functional_test.rb b/railties/lib/rails/generators/test_unit/scaffold/templates/api_functional_test.rb
new file mode 100644
index 0000000000..f302cd6c3d
--- /dev/null
+++ b/railties/lib/rails/generators/test_unit/scaffold/templates/api_functional_test.rb
@@ -0,0 +1,43 @@
+require 'test_helper'
+
+<% module_namespacing do -%>
+class <%= controller_class_name %>ControllerTest < ActionController::TestCase
+  setup do
+    @<%= singular_table_name %> = <%= fixture_name %>(:one)
+<% if mountable_engine? -%>
+    @routes = Engine.routes
+<% end -%>
+  end
+
+  test "should get index" do
+    get :index
+    assert_response :success
+  end
+
+  test "should create <%= singular_table_name %>" do
+    assert_difference('<%= class_name %>.count') do
+      post :create, params: { <%= "#{singular_table_name}: { #{attributes_hash} }" %> }
+    end
+
+    assert_response 201
+  end
+
+  test "should show <%= singular_table_name %>" do
+    get :show, params: { id: <%= "@#{singular_table_name}" %> }
+    assert_response :success
+  end
+
+  test "should update <%= singular_table_name %>" do
+    patch :update, params: { id: <%= "@#{singular_table_name}" %>, <%= "#{singular_table_name}: { #{attributes_hash} }" %> }
+    assert_response 200
+  end
+
+  test "should destroy <%= singular_table_name %>" do
+    assert_difference('<%= class_name %>.count', -1) do
+      delete :destroy, params: { id: <%= "@#{singular_table_name}" %> }
+    end
+
+    assert_response 204
+  end
+end
+<% end -%>
diff --git a/railties/lib/rails/generators/test_unit/scaffold/templates/functional_test.rb b/railties/lib/rails/generators/test_unit/scaffold/templates/functional_test.rb
index 18bd1ece9d..50b98b2631 100644
--- a/railties/lib/rails/generators/test_unit/scaffold/templates/functional_test.rb
+++ b/railties/lib/rails/generators/test_unit/scaffold/templates/functional_test.rb
@@ -3,13 +3,15 @@ require 'test_helper'
 <% module_namespacing do -%>
 class <%= controller_class_name %>ControllerTest < ActionController::TestCase
   setup do
-    @<%= singular_table_name %> = <%= table_name %>(:one)
+    @<%= singular_table_name %> = <%= fixture_name %>(:one)
+<% if mountable_engine? -%>
+    @routes = Engine.routes
+<% end -%>
   end
 
   test "should get index" do
     get :index
     assert_response :success
-    assert_not_nil assigns(:<%= table_name %>)
   end
 
   test "should get new" do
@@ -19,30 +21,30 @@ class <%= controller_class_name %>ControllerTest < ActionController::TestCase
 
   test "should create <%= singular_table_name %>" do
     assert_difference('<%= class_name %>.count') do
-      post :create, <%= "#{singular_table_name}: { #{attributes_hash} }" %>
+      post :create, params: { <%= "#{singular_table_name}: { #{attributes_hash} }" %> }
     end
 
-    assert_redirected_to <%= singular_table_name %>_path(assigns(:<%= singular_table_name %>))
+    assert_redirected_to <%= singular_table_name %>_path(<%= class_name %>.last)
   end
 
   test "should show <%= singular_table_name %>" do
-    get :show, id: <%= "@#{singular_table_name}" %>
+    get :show, params: { id: <%= "@#{singular_table_name}" %> }
     assert_response :success
   end
 
   test "should get edit" do
-    get :edit, id: <%= "@#{singular_table_name}" %>
+    get :edit, params: { id: <%= "@#{singular_table_name}" %> }
     assert_response :success
   end
 
   test "should update <%= singular_table_name %>" do
-    patch :update, id: <%= "@#{singular_table_name}" %>, <%= "#{singular_table_name}: { #{attributes_hash} }" %>
-    assert_redirected_to <%= singular_table_name %>_path(assigns(:<%= singular_table_name %>))
+    patch :update, params: { id: <%= "@#{singular_table_name}" %>, <%= "#{singular_table_name}: { #{attributes_hash} }" %> }
+    assert_redirected_to <%= singular_table_name %>_path(<%= "@#{singular_table_name}" %>)
   end
 
   test "should destroy <%= singular_table_name %>" do
     assert_difference('<%= class_name %>.count', -1) do
-      delete :destroy, id: <%= "@#{singular_table_name}" %>
+      delete :destroy, params: { id: <%= "@#{singular_table_name}" %> }
     end
 
     assert_redirected_to <%= index_helper %>_path
diff --git a/railties/lib/rails/generators/testing/assertions.rb b/railties/lib/rails/generators/testing/assertions.rb
index bd069e4bd0..76758df86d 100644
--- a/railties/lib/rails/generators/testing/assertions.rb
+++ b/railties/lib/rails/generators/testing/assertions.rb
@@ -1,5 +1,3 @@
-require 'shellwords'
-
 module Rails
   module Generators
     module Testing
@@ -23,7 +21,7 @@ module Rails
         #     end
         #   end
         def assert_file(relative, *contents)
-          absolute = File.expand_path(relative, destination_root).shellescape
+          absolute = File.expand_path(relative, destination_root)
           assert File.exist?(absolute), "Expected file #{relative.inspect} to exist, but does not"
 
           read = File.read(absolute) if block_given? || !contents.empty?
diff --git a/railties/lib/rails/generators/testing/behaviour.rb b/railties/lib/rails/generators/testing/behaviour.rb
index fd2ea274e1..94b5e52224 100644
--- a/railties/lib/rails/generators/testing/behaviour.rb
+++ b/railties/lib/rails/generators/testing/behaviour.rb
@@ -2,6 +2,7 @@ require 'active_support/core_ext/class/attribute'
 require 'active_support/core_ext/module/delegation'
 require 'active_support/core_ext/hash/reverse_merge'
 require 'active_support/core_ext/kernel/reporting'
+require 'active_support/testing/stream'
 require 'active_support/concern'
 require 'rails/generators'
 
@@ -10,6 +11,7 @@ module Rails
     module Testing
       module Behaviour
         extend ActiveSupport::Concern
+        include ActiveSupport::Testing::Stream
 
         included do
           class_attribute :destination_root, :current_path, :generator_class, :default_arguments
@@ -90,7 +92,8 @@ module Rails
             cd current_path
           end
 
-          def prepare_destination # :nodoc:
+          # Clears all files and directories in destination.
+          def prepare_destination
             rm_rf(destination_root)
             mkdir_p(destination_root)
           end
@@ -101,22 +104,6 @@ module Rails
             Dir.glob("#{dirname}/[0-9]*_*.rb").grep(/\d+_#{file_name}.rb$/).first
           end
 
-          def capture(stream)
-            stream = stream.to_s
-            captured_stream = Tempfile.new(stream)
-            stream_io = eval("$#{stream}")
-            origin_stream = stream_io.dup
-            stream_io.reopen(captured_stream)
-
-            yield
-
-            stream_io.rewind
-            return captured_stream.read
-          ensure
-            captured_stream.close
-            captured_stream.unlink
-            stream_io.reopen(origin_stream)
-          end
       end
     end
   end
diff --git a/railties/lib/rails/info_controller.rb b/railties/lib/rails/info_controller.rb
index 49e5431a16..778105c5f7 100644
--- a/railties/lib/rails/info_controller.rb
+++ b/railties/lib/rails/info_controller.rb
@@ -17,7 +17,28 @@ class Rails::InfoController < Rails::ApplicationController # :nodoc:
   end
 
   def routes
-    @routes_inspector = ActionDispatch::Routing::RoutesInspector.new(_routes.routes)
-    @page_title = 'Routes'
+    if path = params[:path]
+      path = URI.parser.escape path
+      normalized_path = with_leading_slash path
+      render json: {
+        exact: match_route {|it| it.match normalized_path },
+        fuzzy: match_route {|it| it.spec.to_s.match path }
+      }
+    else
+      @routes_inspector = ActionDispatch::Routing::RoutesInspector.new(_routes.routes)
+      @page_title = 'Routes'
+    end
+  end
+
+  private
+
+  def match_route
+    _routes.routes.select {|route|
+      yield route.path
+    }.map {|route| route.path.spec.to_s }
+  end
+
+  def with_leading_slash(path)
+    ('/' + path).squeeze('/')
   end
 end
diff --git a/railties/lib/rails/mailers_controller.rb b/railties/lib/rails/mailers_controller.rb
index 32740d66da..6143cf2dd9 100644
--- a/railties/lib/rails/mailers_controller.rb
+++ b/railties/lib/rails/mailers_controller.rb
@@ -3,7 +3,7 @@ require 'rails/application_controller'
 class Rails::MailersController < Rails::ApplicationController # :nodoc:
   prepend_view_path ActionDispatch::DebugExceptions::RESCUES_TEMPLATE_PATH
 
-  before_action :require_local!
+  before_action :require_local!, unless: :show_previews?
   before_action :find_preview, only: :preview
 
   def index
@@ -16,31 +16,35 @@ class Rails::MailersController < Rails::ApplicationController # :nodoc:
       @page_title = "Mailer Previews for #{@preview.preview_name}"
       render action: 'mailer'
     else
-      email = File.basename(params[:path])
+      @email_action = File.basename(params[:path])
 
-      if @preview.email_exists?(email)
-        @email = @preview.call(email)
+      if @preview.email_exists?(@email_action)
+        @email = @preview.call(@email_action)
 
         if params[:part]
           part_type = Mime::Type.lookup(params[:part])
 
           if part = find_part(part_type)
             response.content_type = part_type
-            render text: part.respond_to?(:decoded) ? part.decoded : part
+            render plain: part.respond_to?(:decoded) ? part.decoded : part
           else
-            raise AbstractController::ActionNotFound, "Email part '#{part_type}' not found in #{@preview.name}##{email}"
+            raise AbstractController::ActionNotFound, "Email part '#{part_type}' not found in #{@preview.name}##{@email_action}"
           end
         else
-          @part = find_preferred_part(request.format, Mime::HTML, Mime::TEXT)
+          @part = find_preferred_part(request.format, Mime[:html], Mime[:text])
           render action: 'email', layout: false, formats: %w[html]
         end
       else
-        raise AbstractController::ActionNotFound, "Email '#{email}' not found in #{@preview.name}"
+        raise AbstractController::ActionNotFound, "Email '#{@email_action}' not found in #{@preview.name}"
       end
     end
   end
 
   protected
+    def show_previews?
+      ActionMailer::Base.show_previews
+    end
+
     def find_preview
       candidates = []
       params[:path].to_s.scan(%r{/|$}){ candidates << $` }
@@ -54,18 +58,20 @@ class Rails::MailersController < Rails::ApplicationController # :nodoc:
     end
 
     def find_preferred_part(*formats)
-      if @email.multipart?
-        formats.each do |format|
-          return find_part(format) if @email.parts.any?{ |p| p.mime_type == format }
+      formats.each do |format|
+        if part = @email.find_first_mime_type(format)
+          return part
         end
-      else
+      end
+
+      if formats.any?{ |f| @email.mime_type == f }
         @email
       end
     end
 
     def find_part(format)
-      if @email.multipart?
-        @email.parts.find{ |p| p.mime_type == format }
+      if part = @email.find_first_mime_type(format)
+        part
       elsif @email.mime_type == format
         @email
       end
diff --git a/railties/lib/rails/paths.rb b/railties/lib/rails/paths.rb
index 5458036219..e47616a87f 100644
--- a/railties/lib/rails/paths.rb
+++ b/railties/lib/rails/paths.rb
@@ -7,7 +7,7 @@ module Rails
     #   root = Root.new "/rails"
     #   root.add "app/controllers", eager_load: true
     #
-    # The command above creates a new root object and add "app/controllers" as a path.
+    # The command above creates a new root object and adds "app/controllers" as a path.
     # This means we can get a <tt>Rails::Paths::Path</tt> object back like below:
     #
     #   path = root["app/controllers"]
@@ -123,6 +123,10 @@ module Rails
         options[:load_path]     ? load_path!     : skip_load_path!
       end
 
+      def absolute_current # :nodoc:
+        File.expand_path(@current, @root.path)
+      end
+
       def children
         keys = @root.keys.find_all { |k|
           k.start_with?(@current) && k != @current
@@ -175,6 +179,10 @@ module Rails
         @paths
       end
 
+      def extensions # :nodoc:
+        $1.split(',') if @glob =~ /\{([\S]+)\}/
+      end
+
       # Expands all paths against the root and return all unique values.
       def expanded
         raise "You need to set a path root" unless @root.path
diff --git a/railties/lib/rails/rack/logger.rb b/railties/lib/rails/rack/logger.rb
index 9962e6d943..12676b18bc 100644
--- a/railties/lib/rails/rack/logger.rb
+++ b/railties/lib/rails/rack/logger.rb
@@ -7,6 +7,10 @@ require 'rack/body_proxy'
 module Rails
   module Rack
     # Sets log tags, logs the request, calls the app, and flushes the logs.
+    #
+    # Log tags (+taggers+) can be an Array containing: methods that the +request+
+    # object responds to, objects that respond to +to_s+ or Proc objects that accept
+    # an instance of the +request+ object.
     class Logger < ActiveSupport::LogSubscriber
       def initialize(app, taggers = nil)
         @app          = app
diff --git a/railties/lib/rails/ruby_version_check.rb b/railties/lib/rails/ruby_version_check.rb
index aea3d2339c..67a19d8a94 100644
--- a/railties/lib/rails/ruby_version_check.rb
+++ b/railties/lib/rails/ruby_version_check.rb
@@ -1,13 +1,13 @@
-if RUBY_VERSION < '2.2.0'
+if RUBY_VERSION < '2.2.2' && RUBY_ENGINE == 'ruby'
   desc = defined?(RUBY_DESCRIPTION) ? RUBY_DESCRIPTION : "ruby #{RUBY_VERSION} (#{RUBY_RELEASE_DATE})"
   abort <<-end_message
 
-    Rails 5 requires to run on Ruby 2.2.0 or newer.
+    Rails 5 requires Ruby 2.2.2 or newer.
 
     You're running
       #{desc}
 
-    Please upgrade to Ruby 2.2.0 or newer to continue.
+    Please upgrade to Ruby 2.2.2 or newer to continue.
 
   end_message
 end
diff --git a/railties/lib/rails/source_annotation_extractor.rb b/railties/lib/rails/source_annotation_extractor.rb
index 9b058a1848..8dd87b6cc5 100644
--- a/railties/lib/rails/source_annotation_extractor.rb
+++ b/railties/lib/rails/source_annotation_extractor.rb
@@ -3,7 +3,7 @@
 #   rake notes
 #   rake notes:optimize
 #
-# and friends. See <tt>rake -T notes</tt> and <tt>railties/lib/tasks/annotations.rake</tt>.
+# and friends. See <tt>rake -T notes</tt> and <tt>railties/lib/rails/tasks/annotations.rake</tt>.
 #
 # Annotation objects are triplets <tt>:line</tt>, <tt>:tag</tt>, <tt>:text</tt> that
 # represent the line where the annotation lives, its tag, and its text. Note
diff --git a/railties/lib/rails/tasks.rb b/railties/lib/rails/tasks.rb
index 2f82d1285d..d3e33584d7 100644
--- a/railties/lib/rails/tasks.rb
+++ b/railties/lib/rails/tasks.rb
@@ -3,14 +3,17 @@ require 'rake'
 # Load Rails Rakefile extensions
 %w(
   annotations
-  documentation
+  dev
   framework
+  initializers
   log
   middleware
   misc
+  restart
   routes
-  statistics
   tmp
-).each do |task|
+).tap { |arr|
+  arr << 'statistics' if Rake.application.current_scope.empty?
+}.each do |task|
   load "rails/tasks/#{task}.rake"
 end
diff --git a/railties/lib/rails/tasks/dev.rake b/railties/lib/rails/tasks/dev.rake
new file mode 100644
index 0000000000..e949172d3f
--- /dev/null
+++ b/railties/lib/rails/tasks/dev.rake
@@ -0,0 +1,15 @@
+namespace :dev do
+  task :cache do
+    desc 'Toggle development mode caching on/off'
+
+    if File.exist? 'tmp/caching-dev.txt'
+      File.delete 'tmp/caching-dev.txt'
+      puts 'Development mode is no longer being cached.'
+    else
+      FileUtils.touch 'tmp/caching-dev.txt'
+      puts 'Development mode is now being cached.'
+    end
+
+    FileUtils.touch 'tmp/restart.txt'
+  end
+end
diff --git a/railties/lib/rails/tasks/documentation.rake b/railties/lib/rails/tasks/documentation.rake
deleted file mode 100644
index 8544890553..0000000000
--- a/railties/lib/rails/tasks/documentation.rake
+++ /dev/null
@@ -1,70 +0,0 @@
-begin
-  require 'rdoc/task'
-rescue LoadError
-  # Rubinius installs RDoc as a gem, and for this interpreter "rdoc/task" is
-  # available only if the application bundle includes "rdoc" (normally as a
-  # dependency of the "sdoc" gem.)
-  #
-  # If RDoc is not available it is fine that we do not generate the tasks that
-  # depend on it. Just be robust to this gotcha and go on.
-else
-  require 'rails/api/task'
-
-  # Monkey-patch to remove redoc'ing and clobber descriptions to cut down on rake -T noise
-  class RDocTaskWithoutDescriptions < RDoc::Task
-    include ::Rake::DSL
-
-    def define
-      task rdoc_task_name
-
-      task rerdoc_task_name => [clobber_task_name, rdoc_task_name]
-
-      task clobber_task_name do
-        rm_r rdoc_dir rescue nil
-      end
-
-      task :clobber => [clobber_task_name]
-
-      directory @rdoc_dir
-      task rdoc_task_name => [rdoc_target]
-      file rdoc_target => @rdoc_files + [Rake.application.rakefile] do
-        rm_r @rdoc_dir rescue nil
-        @before_running_rdoc.call if @before_running_rdoc
-        args = option_list + @rdoc_files
-        if @external
-          argstring = args.join(' ')
-          sh %{ruby -Ivendor vendor/rd #{argstring}}
-        else
-          require 'rdoc/rdoc'
-          RDoc::RDoc.new.document(args)
-        end
-      end
-      self
-    end
-  end
-
-  namespace :doc do
-    RDocTaskWithoutDescriptions.new("app") { |rdoc|
-      rdoc.rdoc_dir = 'doc/app'
-      rdoc.template = ENV['template'] if ENV['template']
-      rdoc.title    = ENV['title'] || "Rails Application Documentation"
-      rdoc.options << '--line-numbers'
-      rdoc.options << '--charset' << 'utf-8'
-      rdoc.rdoc_files.include('README.rdoc')
-      rdoc.rdoc_files.include('app/**/*.rb')
-      rdoc.rdoc_files.include('lib/**/*.rb')
-    }
-    Rake::Task['doc:app'].comment = "Generate docs for the app -- also available doc:rails, doc:guides (options: TEMPLATE=/rdoc-template.rb, TITLE=\"Custom Title\")"
-
-    # desc 'Generate documentation for the Rails framework.'
-    Rails::API::AppTask.new('rails')
-  end
-end
-
-namespace :doc do
-  task :guides do
-    rails_gem_dir = Gem::Specification.find_by_name("rails").gem_dir
-    require File.expand_path(File.join(rails_gem_dir, "/guides/rails_guides"))
-    RailsGuides::Generator.new(Rails.root.join("doc/guides")).generate
-  end
-end
diff --git a/railties/lib/rails/tasks/engine.rake b/railties/lib/rails/tasks/engine.rake
index 16ad1bfc84..c51524f8f6 100644
--- a/railties/lib/rails/tasks/engine.rake
+++ b/railties/lib/rails/tasks/engine.rake
@@ -40,7 +40,7 @@ namespace :db do
   desc "Rolls the schema back to the previous version (specify steps w/ STEP=n)."
   app_task "rollback"
 
-  desc "Create a db/schema.rb file that can be portably used against any DB supported by AR"
+  desc "Create a db/schema.rb file that can be portably used against any DB supported by Active Record"
   app_task "schema:dump"
 
   desc "Load a schema.rb file into the database"
diff --git a/railties/lib/rails/tasks/framework.rake b/railties/lib/rails/tasks/framework.rake
index a1c805f8aa..904b9d9ad6 100644
--- a/railties/lib/rails/tasks/framework.rake
+++ b/railties/lib/rails/tasks/framework.rake
@@ -32,35 +32,37 @@ namespace :rails do
           FileUtils.cp_r src_name, dst_name
         end
       end
-     end
+    end
   end
 
   namespace :update do
-    def invoke_from_app_generator(method)
-      app_generator.send(method)
-    end
+    class RailsUpdate
+      def self.invoke_from_app_generator(method)
+        app_generator.send(method)
+      end
 
-    def app_generator
-      @app_generator ||= begin
-        require 'rails/generators'
-        require 'rails/generators/rails/app/app_generator'
-        gen = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true },
-                                                             destination_root: Rails.root
-        File.exist?(Rails.root.join("config", "application.rb")) ?
-          gen.send(:app_const) : gen.send(:valid_const?)
-        gen
+      def self.app_generator
+        @app_generator ||= begin
+          require 'rails/generators'
+          require 'rails/generators/rails/app/app_generator'
+          gen = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true },
+            destination_root: Rails.root
+          File.exist?(Rails.root.join("config", "application.rb")) ?
+            gen.send(:app_const) : gen.send(:valid_const?)
+          gen
+        end
       end
     end
 
     # desc "Update config/boot.rb from your current rails install"
     task :configs do
-      invoke_from_app_generator :create_boot_file
-      invoke_from_app_generator :update_config_files
+      RailsUpdate.invoke_from_app_generator :create_boot_file
+      RailsUpdate.invoke_from_app_generator :update_config_files
     end
 
     # desc "Adds new executables to the application bin/ directory"
     task :bin do
-      invoke_from_app_generator :create_bin_files
+      RailsUpdate.invoke_from_app_generator :create_bin_files
     end
   end
 end
diff --git a/railties/lib/rails/tasks/initializers.rake b/railties/lib/rails/tasks/initializers.rake
new file mode 100644
index 0000000000..2968b5cb53
--- /dev/null
+++ b/railties/lib/rails/tasks/initializers.rake
@@ -0,0 +1,6 @@
+desc "Print out all defined initializers in the order they are invoked by Rails."
+task initializers: :environment do
+  Rails.application.initializers.tsort_each do |initializer|
+    puts initializer.name
+  end
+end
diff --git a/railties/lib/rails/tasks/restart.rake b/railties/lib/rails/tasks/restart.rake
new file mode 100644
index 0000000000..f36c86d81b
--- /dev/null
+++ b/railties/lib/rails/tasks/restart.rake
@@ -0,0 +1,5 @@
+desc "Restart app by touching tmp/restart.txt"
+task :restart do
+  FileUtils.mkdir_p('tmp')
+  FileUtils.touch('tmp/restart.txt')
+end
diff --git a/railties/lib/rails/tasks/tmp.rake b/railties/lib/rails/tasks/tmp.rake
index b33ae9862b..9162ef234a 100644
--- a/railties/lib/rails/tasks/tmp.rake
+++ b/railties/lib/rails/tasks/tmp.rake
@@ -11,7 +11,7 @@ namespace :tmp do
 
   tmp_dirs.each { |d| directory d }
 
-  desc "Creates tmp directories for sessions, cache, sockets, and pids"
+  desc "Creates tmp directories for cache, sockets, and pids"
   task create: tmp_dirs
 
   namespace :cache do
diff --git a/railties/lib/rails/templates/rails/mailers/email.html.erb b/railties/lib/rails/templates/rails/mailers/email.html.erb
index 0b08a01896..fed96fbc85 100644
--- a/railties/lib/rails/templates/rails/mailers/email.html.erb
+++ b/railties/lib/rails/templates/rails/mailers/email.html.erb
@@ -39,6 +39,10 @@
     padding: 1px;
   }
 
+  dd:empty:before {
+    content: "\00a0"; // &nbsp;
+  }
+
   iframe {
     border: 0;
     width: 100%;
@@ -84,22 +88,43 @@
     <% unless @email.attachments.nil? || @email.attachments.empty? %>
       <dt>Attachments:</dt>
       <dd>
-        <%= @email.attachments.map { |a| a.respond_to?(:original_filename) ? a.original_filename : a.filename }.inspect %>
+        <%= @email.attachments.map { |a| a.respond_to?(:original_filename) ? a.original_filename : a.filename }.join(', ') %>
       </dd>
     <% end %>
 
     <% if @email.multipart? %>
       <dd>
-        <select onchange="document.getElementsByName('messageBody')[0].src=this.options[this.selectedIndex].value;">
-          <option <%= request.format == Mime::HTML ? 'selected' : '' %> value="?part=text%2Fhtml">View as HTML email</option>
-          <option <%= request.format == Mime::TEXT ? 'selected' : '' %> value="?part=text%2Fplain">View as plain-text email</option>
+        <select onchange="formatChanged(this);">
+          <option <%= request.format == Mime[:html] ? 'selected' : '' %> value="?part=text%2Fhtml">View as HTML email</option>
+          <option <%= request.format == Mime[:text] ? 'selected' : '' %> value="?part=text%2Fplain">View as plain-text email</option>
         </select>
       </dd>
     <% end %>
   </dl>
 </header>
 
-<iframe seamless name="messageBody" src="?part=<%= Rack::Utils.escape(@part.mime_type) %>"></iframe>
+<% if @part && @part.mime_type %>
+  <iframe seamless name="messageBody" src="?part=<%= Rack::Utils.escape(@part.mime_type) %>"></iframe>
+<% else %>
+  <p>
+    You are trying to preview an email that does not have any content.
+    This is probably because the <em>mail</em> method has not been called in <em><%= @preview.preview_name %>#<%= @email_action %></em>.
+  </p>
+<% end %>
+
+<script>
+  function formatChanged(form) {
+    var part_name = form.options[form.selectedIndex].value
+    var iframe =document.getElementsByName('messageBody')[0];
+    iframe.contentWindow.location.replace(part_name);
+
+    if (history.replaceState) {
+      var url    = location.pathname.replace(/\.(txt|html)$/, '');
+      var format = /html/.test(part_name) ? '.html' : '.txt';
+      window.history.replaceState({}, '', url + format);
+    }
+  }
+</script>
 
 </body>
 </html>
diff --git a/railties/lib/rails/templates/rails/mailers/index.html.erb b/railties/lib/rails/templates/rails/mailers/index.html.erb
index c4c9757d57..000930c039 100644
--- a/railties/lib/rails/templates/rails/mailers/index.html.erb
+++ b/railties/lib/rails/templates/rails/mailers/index.html.erb
@@ -1,8 +1,8 @@
 <% @previews.each do |preview| %>
-<h3><%= link_to preview.preview_name.titleize, "/rails/mailers/#{preview.preview_name}" %></h3>
+<h3><%= link_to preview.preview_name.titleize, url_for(controller: "rails/mailers", action: "preview", path: preview.preview_name) %></h3>
 <ul>
 <% preview.emails.each do |email| %>
-<li><%= link_to email, "/rails/mailers/#{preview.preview_name}/#{email}" %></li>
+<li><%= link_to email, url_for(controller: "rails/mailers", action: "preview", path: "#{preview.preview_name}/#{email}") %></li>
 <% end %>
 </ul>
 <% end %>
diff --git a/railties/lib/rails/templates/rails/mailers/mailer.html.erb b/railties/lib/rails/templates/rails/mailers/mailer.html.erb
index 607c8d1677..c12ead0f90 100644
--- a/railties/lib/rails/templates/rails/mailers/mailer.html.erb
+++ b/railties/lib/rails/templates/rails/mailers/mailer.html.erb
@@ -1,6 +1,6 @@
 <h3><%= @preview.preview_name.titleize %></h3>
 <ul>
 <% @preview.emails.each do |email| %>
-<li><%= link_to email, "/rails/mailers/#{@preview.preview_name}/#{email}" %></li>
+<li><%= link_to email, url_for(controller: "rails/mailers", action: "preview", path: "#{@preview.preview_name}/#{email}") %></li>
 <% end %>
 </ul>
diff --git a/railties/lib/rails/templates/rails/welcome/index.html.erb b/railties/lib/rails/templates/rails/welcome/index.html.erb
index 6726c23fc9..acf04af416 100644
--- a/railties/lib/rails/templates/rails/welcome/index.html.erb
+++ b/railties/lib/rails/templates/rails/welcome/index.html.erb
@@ -18,7 +18,9 @@
         color: #000;
       }
 
-      a  {color: #03c}
+      a {
+        color: #03c;
+      }
 
       a:hover {
         background-color: #03c;
@@ -64,7 +66,10 @@
         height: 64px;
       }
 
-      #header h1, #header h2 {margin: 0}
+      #header h1,
+      #header h2 {
+        margin: 0;
+      }
 
       #header h2 {
         color: #888;
@@ -104,7 +109,9 @@
         color: #555;
       }
 
-      #about-content td.value {color: #000}
+      #about-content td.value {
+        color: #000;
+      }
 
       #about-content ul {
         padding: 0;
diff --git a/railties/lib/rails/test_help.rb b/railties/lib/rails/test_help.rb
index c837fadb40..5cc1b5b219 100644
--- a/railties/lib/rails/test_help.rb
+++ b/railties/lib/rails/test_help.rb
@@ -2,18 +2,14 @@
 # so fixtures aren't loaded into that environment
 abort("Abort testing: Your Rails environment is running in production mode!") if Rails.env.production?
 
-require 'active_support/testing/autorun'
+require "rails/test_unit/minitest_plugin"
 require 'active_support/test_case'
 require 'action_controller'
 require 'action_controller/test_case'
 require 'action_dispatch/testing/integration'
 require 'rails/generators/test_case'
 
-# Config Rails backtrace in tests.
-require 'rails/backtrace_cleaner'
-if ENV["BACKTRACE"].nil?
-  Minitest.backtrace_filter = Rails.backtrace_cleaner
-end
+require 'active_support/testing/autorun'
 
 if defined?(ActiveRecord::Base)
   ActiveRecord::Migration.maintain_test_schema!
@@ -21,6 +17,7 @@ if defined?(ActiveRecord::Base)
   class ActiveSupport::TestCase
     include ActiveRecord::TestFixtures
     self.fixture_path = "#{Rails.root}/test/fixtures/"
+    self.file_fixture_path = self.fixture_path + "files"
   end
 
   ActionDispatch::IntegrationTest.fixture_path = ActiveSupport::TestCase.fixture_path
@@ -31,13 +28,15 @@ if defined?(ActiveRecord::Base)
 end
 
 class ActionController::TestCase
-  setup do
+  def before_setup # :nodoc:
     @routes = Rails.application.routes
+    super
   end
 end
 
 class ActionDispatch::IntegrationTest
-  setup do
+  def before_setup # :nodoc:
     @routes = Rails.application.routes
+    super
   end
 end
diff --git a/railties/lib/rails/test_unit/minitest_plugin.rb b/railties/lib/rails/test_unit/minitest_plugin.rb
new file mode 100644
index 0000000000..d1ba35a5ec
--- /dev/null
+++ b/railties/lib/rails/test_unit/minitest_plugin.rb
@@ -0,0 +1,88 @@
+require "active_support/core_ext/module/attribute_accessors"
+require "rails/test_unit/reporter"
+require "rails/test_unit/test_requirer"
+
+module Minitest
+  mattr_accessor(:hide_aggregated_results) { false }
+
+  module AggregatedResultSuppresion
+    def aggregated_results
+      super unless Minitest.hide_aggregated_results
+    end
+  end
+
+  SummaryReporter.prepend AggregatedResultSuppresion
+
+  def self.plugin_rails_options(opts, options)
+    opts.separator ""
+    opts.separator "Usage: bin/rails test [options] [files or directories]"
+    opts.separator "You can run a single test by appending a line number to a filename:"
+    opts.separator ""
+    opts.separator "    bin/rails test test/models/user_test.rb:27"
+    opts.separator ""
+    opts.separator "You can run multiple files and directories at the same time:"
+    opts.separator ""
+    opts.separator "    bin/rails test test/controllers test/integration/login_test.rb"
+    opts.separator ""
+    opts.separator "By default test failures and errors are reported inline during a run."
+    opts.separator ""
+
+    opts.separator "Rails options:"
+    opts.on("-e", "--environment ENV",
+            "Run tests in the ENV environment") do |env|
+      options[:environment] = env.strip
+    end
+
+    opts.on("-b", "--backtrace",
+            "Show the complete backtrace") do
+      options[:full_backtrace] = true
+    end
+
+    opts.on("-d", "--defer-output",
+            "Output test failures and errors after the test run") do
+      options[:output_inline] = false
+    end
+
+    opts.on("-f", "--fail-fast",
+            "Abort test run on first failure") do
+      options[:fail_fast] = true
+    end
+
+    options[:output_inline] = true
+    options[:patterns] = opts.order!
+  end
+
+  # Running several Rake tasks in a single command would trip up the runner,
+  # as the patterns would also contain the other Rake tasks.
+  def self.rake_run(patterns) # :nodoc:
+    @rake_patterns = patterns
+    run
+  end
+
+  def self.plugin_rails_init(options)
+    self.run_with_rails_extension = true
+
+    ENV["RAILS_ENV"] = options[:environment] || "test"
+
+    unless run_with_autorun
+      patterns = defined?(@rake_patterns) ? @rake_patterns : options[:patterns]
+      ::Rails::TestRequirer.require_files(patterns)
+    end
+
+    unless options[:full_backtrace] || ENV["BACKTRACE"]
+      # Plugin can run without Rails loaded, check before filtering.
+      Minitest.backtrace_filter = ::Rails.backtrace_cleaner if ::Rails.respond_to?(:backtrace_cleaner)
+    end
+
+    # Disable the extra failure output after a run, unless output is deferred.
+    self.hide_aggregated_results = options[:output_inline]
+
+    self.reporter << ::Rails::TestUnitReporter.new(options[:io], options)
+  end
+
+  mattr_accessor(:run_with_autorun)         { false }
+  mattr_accessor(:run_with_rails_extension) { false }
+end
+
+Minitest.load_plugins
+Minitest.extensions << 'rails'
diff --git a/railties/lib/rails/test_unit/reporter.rb b/railties/lib/rails/test_unit/reporter.rb
new file mode 100644
index 0000000000..e1fe92a11b
--- /dev/null
+++ b/railties/lib/rails/test_unit/reporter.rb
@@ -0,0 +1,64 @@
+require "active_support/core_ext/class/attribute"
+require "minitest"
+
+module Rails
+  class TestUnitReporter < Minitest::StatisticsReporter
+    class_attribute :executable
+    self.executable = "bin/rails test"
+
+    def record(result)
+      super
+
+      if output_inline? && result.failure && (!result.skipped? || options[:verbose])
+        io.puts
+        io.puts
+        io.puts result.failures.map(&:message)
+        io.puts
+        io.puts format_rerun_snippet(result)
+        io.puts
+      end
+
+      if fail_fast? && result.failure && !result.error? && !result.skipped?
+        raise Interrupt
+      end
+    end
+
+    def report
+      return if output_inline? || filtered_results.empty?
+      io.puts
+      io.puts "Failed tests:"
+      io.puts
+      io.puts aggregated_results
+    end
+
+    def aggregated_results # :nodoc:
+      filtered_results.map { |result| format_rerun_snippet(result) }.join "\n"
+    end
+
+    def filtered_results
+      if options[:verbose]
+        results
+      else
+        results.reject(&:skipped?)
+      end
+    end
+
+    def relative_path_for(file)
+      file.sub(/^#{Rails.root}\/?/, '')
+    end
+
+    private
+      def output_inline?
+        options[:output_inline]
+      end
+
+      def fail_fast?
+        options[:fail_fast]
+      end
+
+      def format_rerun_snippet(result)
+        location, line = result.method(result.name).source_location
+        "#{self.executable} #{relative_path_for(location)}:#{line}"
+      end
+  end
+end
diff --git a/railties/lib/rails/test_unit/sub_test_task.rb b/railties/lib/rails/test_unit/sub_test_task.rb
deleted file mode 100644
index 6fa96d2ced..0000000000
--- a/railties/lib/rails/test_unit/sub_test_task.rb
+++ /dev/null
@@ -1,126 +0,0 @@
-require 'rake/testtask'
-
-module Rails
-  class TestTask < Rake::TestTask # :nodoc: all
-    # A utility class which is used primarily in "rails/test_unit/testing.rake"
-    # to help define rake tasks corresponding to <tt>rake test</tt>.
-    #
-    # This class takes a TestInfo class and defines the appropriate rake task
-    # based on the information, then invokes it.
-    class TestCreator # :nodoc:
-      def initialize(info)
-        @info = info
-      end
-
-      def invoke_rake_task
-        if @info.files.any?
-          create_and_run_single_test
-          reset_application_tasks
-        else
-          Rake::Task[ENV['TEST'] ? 'test:single' : 'test:run'].invoke
-        end
-      end
-
-      private
-
-        def create_and_run_single_test
-          Rails::TestTask.new('test:single') { |t|
-            t.test_files = @info.files
-          }
-          ENV['TESTOPTS'] ||= @info.opts
-          Rake::Task['test:single'].invoke
-        end
-
-        def reset_application_tasks
-          Rake.application.top_level_tasks.replace @info.tasks
-        end
-    end
-
-    # This is a utility class used by the <tt>TestTask::TestCreator</tt> class.
-    # This class takes a set of test tasks and checks to see if they correspond
-    # to test files (or can be transformed into test files). Calling <tt>files</tt>
-    # provides the set of test files and is used when initializing tests after
-    # a call to <tt>rake test</tt>.
-    class TestInfo # :nodoc:
-      def initialize(tasks)
-        @tasks = tasks
-        @files = nil
-      end
-
-      def files
-        @files ||= @tasks.map { |task|
-          [task, translate(task)].find { |file| test_file?(file) }
-        }.compact
-      end
-
-      def translate(file)
-        if file =~ /^app\/(.*)$/
-          "test/#{$1.sub(/\.rb$/, '')}_test.rb"
-        else
-          "test/#{file}_test.rb"
-        end
-      end
-
-      def tasks
-        @tasks - test_file_tasks - opt_names
-      end
-
-      def opts
-        opts = opt_names
-        if opts.any?
-          "-n #{opts.join ' '}"
-        end
-      end
-
-      private
-
-      def test_file_tasks
-        @tasks.find_all { |task|
-          [task, translate(task)].any? { |file| test_file?(file) }
-        }
-      end
-
-      def test_file?(file)
-        file =~ /^test/ && File.file?(file) && !File.directory?(file)
-      end
-
-      def opt_names
-        (@tasks - test_file_tasks).reject { |t| task_defined? t }
-      end
-
-      def task_defined?(task)
-        Rake::Task.task_defined? task
-      end
-    end
-
-    def self.test_creator(tasks)
-      info = TestInfo.new(tasks)
-      TestCreator.new(info)
-    end
-
-    def initialize(name = :test)
-      super
-      @libs << "test" # lib *and* test seem like a better default
-    end
-
-    def define
-      task @name do
-        if ENV['TESTOPTS']
-          ARGV.replace Shellwords.split ENV['TESTOPTS']
-        end
-        libs = @libs - $LOAD_PATH
-        $LOAD_PATH.unshift(*libs)
-        file_list.each { |fl|
-          FileList[fl].to_a.each { |f| require File.expand_path f }
-        }
-      end
-    end
-  end
-
-  # Silence the default description to cut down on `rake -T` noise.
-  class SubTestTask < Rake::TestTask # :nodoc:
-    def desc(string)
-      # Ignore the description.
-    end
-  end
-end
diff --git a/railties/lib/rails/test_unit/test_requirer.rb b/railties/lib/rails/test_unit/test_requirer.rb
new file mode 100644
index 0000000000..83d2c55ffd
--- /dev/null
+++ b/railties/lib/rails/test_unit/test_requirer.rb
@@ -0,0 +1,28 @@
+require 'active_support/core_ext/object/blank'
+require 'rake/file_list'
+
+module Rails
+  class TestRequirer # :nodoc:
+    class << self
+      def require_files(patterns)
+        patterns = expand_patterns(patterns)
+
+        Rake::FileList[patterns.compact.presence || 'test/**/*_test.rb'].to_a.each do |file|
+          require File.expand_path(file)
+        end
+      end
+
+      private
+        def expand_patterns(patterns)
+          patterns.map do |arg|
+            arg = arg.gsub(/:(\d+)?$/, '')
+            if Dir.exist?(arg)
+              "#{arg}/**/*_test.rb"
+            else
+              arg
+            end
+          end
+        end
+    end
+  end
+end
diff --git a/railties/lib/rails/test_unit/testing.rake b/railties/lib/rails/test_unit/testing.rake
index d836c0d6d6..6676c6a079 100644
--- a/railties/lib/rails/test_unit/testing.rake
+++ b/railties/lib/rails/test_unit/testing.rake
@@ -1,11 +1,13 @@
-require 'rake/testtask'
-require 'rails/test_unit/sub_test_task'
+gem 'minitest'
+require 'minitest'
+require 'rails/test_unit/minitest_plugin'
 
 task default: :test
 
 desc "Runs all tests in test folder"
 task :test do
-  Rails::TestTask.test_creator(Rake.application.top_level_tasks).invoke_rake_task
+  $: << "test"
+  Minitest.rake_run(["test"])
 end
 
 namespace :test do
@@ -14,30 +16,30 @@ namespace :test do
     # If used with Active Record, this task runs before the database schema is synchronized.
   end
 
-  Rails::TestTask.new(:run) do |t|
-    t.pattern = "test/**/*_test.rb"
-  end
+  task :run => %w[test]
 
   desc "Run tests quickly, but also reset db"
   task :db => %w[db:test:prepare test]
 
-  Rails::TestTask.new(single: "test:prepare")
-
   ["models", "helpers", "controllers", "mailers", "integration", "jobs"].each do |name|
-    Rails::TestTask.new(name => "test:prepare") do |t|
-      t.pattern = "test/#{name}/**/*_test.rb"
+    task name => "test:prepare" do
+      $: << "test"
+      Minitest.rake_run(["test/#{name}"])
     end
   end
 
-  Rails::TestTask.new(generators: "test:prepare") do |t|
-    t.pattern = "test/lib/generators/**/*_test.rb"
+  task :generators => "test:prepare" do
+    $: << "test"
+    Minitest.rake_run(["test/lib/generators"])
   end
 
-  Rails::TestTask.new(units: "test:prepare") do |t|
-    t.pattern = 'test/{models,helpers,unit}/**/*_test.rb'
+  task :units => "test:prepare" do
+    $: << "test"
+    Minitest.rake_run(["test/models", "test/helpers", "test/unit"])
   end
 
-  Rails::TestTask.new(functionals: "test:prepare") do |t|
-    t.pattern = 'test/{controllers,mailers,functional}/**/*_test.rb'
+  task :functionals => "test:prepare" do
+    $: << "test"
+    Minitest.rake_run(["test/controllers", "test/mailers", "test/functional"])
   end
 end
diff --git a/railties/railties.gemspec b/railties/railties.gemspec
index 7a1c897e3d..a06336f698 100644
--- a/railties/railties.gemspec
+++ b/railties/railties.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |s|
   s.summary     = 'Tools for creating, working with, and running Rails applications.'
   s.description = 'Rails internals: application bootup, plugins, generators, and rake tasks.'
 
-  s.required_ruby_version = '>= 2.2.0'
+  s.required_ruby_version = '>= 2.2.2'
 
   s.license = 'MIT'
 
@@ -15,10 +15,10 @@ Gem::Specification.new do |s|
   s.email    = 'david@loudthinking.com'
   s.homepage = 'http://www.rubyonrails.org'
 
-  s.files        = Dir['CHANGELOG.md', 'README.rdoc', 'RDOC_MAIN.rdoc', 'bin/**/*', 'lib/**/{*,.[a-z]*}']
+  s.files        = Dir['CHANGELOG.md', 'README.rdoc', 'MIT-LICENSE', 'RDOC_MAIN.rdoc', 'exe/**/*', 'lib/**/{*,.[a-z]*}']
   s.require_path = 'lib'
 
-  s.bindir      = 'bin'
+  s.bindir      = 'exe'
   s.executables = ['rails']
 
   s.rdoc_options << '--exclude' << '.'
@@ -28,6 +28,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'rake', '>= 0.8.7'
   s.add_dependency 'thor', '>= 0.18.1', '< 2.0'
+  s.add_dependency 'method_source'
 
   s.add_development_dependency 'actionview', version
 end
diff --git a/railties/test/abstract_unit.rb b/railties/test/abstract_unit.rb
index 0749615d03..794d180e5d 100644
--- a/railties/test/abstract_unit.rb
+++ b/railties/test/abstract_unit.rb
@@ -4,6 +4,7 @@ require File.expand_path("../../../load_paths", __FILE__)
 
 require 'stringio'
 require 'active_support/testing/autorun'
+require 'active_support/testing/stream'
 require 'fileutils'
 
 require 'active_support'
@@ -28,26 +29,5 @@ def jruby_skip(message = '')
 end
 
 class ActiveSupport::TestCase
-  # FIXME: we have tests that depend on run order, we should fix that and
-  # remove this method call.
-  self.test_order = :sorted
-
-  private
-
-  def capture(stream)
-    stream = stream.to_s
-    captured_stream = Tempfile.new(stream)
-    stream_io = eval("$#{stream}")
-    origin_stream = stream_io.dup
-    stream_io.reopen(captured_stream)
-
-    yield
-
-    stream_io.rewind
-    return captured_stream.read
-  ensure
-    captured_stream.close
-    captured_stream.unlink
-    stream_io.reopen(origin_stream)
-  end
+  include ActiveSupport::Testing::Stream
 end
diff --git a/railties/test/app_rails_loader_test.rb b/railties/test/app_loader_test.rb
index d4885447e6..5946c8fd4c 100644
--- a/railties/test/app_rails_loader_test.rb
+++ b/railties/test/app_loader_test.rb
@@ -1,11 +1,11 @@
 require 'tmpdir'
 require 'abstract_unit'
-require 'rails/app_rails_loader'
+require 'rails/app_loader'
 
-class AppRailsLoaderTest < ActiveSupport::TestCase
+class AppLoaderTest < ActiveSupport::TestCase
   def loader
     @loader ||= Class.new do
-      extend Rails::AppRailsLoader
+      extend Rails::AppLoader
 
       def self.exec_arguments
         @exec_arguments
@@ -23,7 +23,7 @@ class AppRailsLoaderTest < ActiveSupport::TestCase
   end
 
   def expects_exec(exe)
-    assert_equal [Rails::AppRailsLoader::RUBY, exe], loader.exec_arguments
+    assert_equal [Rails::AppLoader::RUBY, exe], loader.exec_arguments
   end
 
   setup do
@@ -38,20 +38,20 @@ class AppRailsLoaderTest < ActiveSupport::TestCase
     test "is not in a Rails application if #{exe} is not found in the current or parent directories" do
       def loader.find_executables; end
 
-      assert !loader.exec_app_rails
+      assert !loader.exec_app
     end
 
     test "is not in a Rails application if #{exe} exists but is a folder" do
       FileUtils.mkdir_p(exe)
 
-      assert !loader.exec_app_rails
+      assert !loader.exec_app
     end
 
     ['APP_PATH', 'ENGINE_PATH'].each do |keyword|
       test "is in a Rails application if #{exe} exists and contains #{keyword}" do
         write exe, keyword
 
-        loader.exec_app_rails
+        loader.exec_app
 
         expects_exec exe
       end
@@ -59,7 +59,7 @@ class AppRailsLoaderTest < ActiveSupport::TestCase
       test "is not in a Rails application if #{exe} exists but doesn't contain #{keyword}" do
         write exe
 
-        assert !loader.exec_app_rails
+        assert !loader.exec_app
       end
 
       test "is in a Rails application if parent directory has #{exe} containing #{keyword} and chdirs to the root directory" do
@@ -68,7 +68,7 @@ class AppRailsLoaderTest < ActiveSupport::TestCase
 
         Dir.chdir('foo/bar')
 
-        loader.exec_app_rails
+        loader.exec_app
 
         expects_exec exe
 
diff --git a/railties/test/application/asset_debugging_test.rb b/railties/test/application/asset_debugging_test.rb
index 9a571fac3a..8b83784ed6 100644
--- a/railties/test/application/asset_debugging_test.rb
+++ b/railties/test/application/asset_debugging_test.rb
@@ -7,7 +7,10 @@ module ApplicationTests
     include Rack::Test::Methods
 
     def setup
-      build_app(initializers: true)
+      # FIXME: shush Sass warning spam, not relevant to testing Railties
+      Kernel.silence_warnings do
+        build_app(initializers: true)
+      end
 
       app_file "app/assets/javascripts/application.js", "//= require_tree ."
       app_file "app/assets/javascripts/xmlhr.js", "function f1() { alert(); }"
@@ -33,12 +36,19 @@ module ApplicationTests
       teardown_app
     end
 
+    # FIXME: shush Sass warning spam, not relevant to testing Railties
+    def get(*)
+      Kernel.silence_warnings { super }
+    end
+
     test "assets are concatenated when debug is off and compile is off either if debug_assets param is provided" do
       # config.assets.debug and config.assets.compile are false for production environment
       ENV["RAILS_ENV"] = "production"
-      output = Dir.chdir(app_path){ `bundle exec rake assets:precompile --trace 2>&1` }
+      output = Dir.chdir(app_path){ `bin/rake assets:precompile --trace 2>&1` }
       assert $?.success?, output
-      require "#{app_path}/config/environment"
+
+      # Load app env
+      app "production"
 
       class ::PostsController < ActionController::Base ; end
 
@@ -48,17 +58,16 @@ module ApplicationTests
       assert_no_match(/<script src="\/assets\/xmlhr-([0-z]+)\.js"><\/script>/, last_response.body)
     end
 
-    test "assets aren't concatenated when compile is true is on and debug_assets params is true" do
+    test "assets are served with sourcemaps when compile is true and debug_assets params is true" do
       add_to_env_config "production", "config.assets.compile = true"
 
-      ENV["RAILS_ENV"] = "production"
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "production"
 
       class ::PostsController < ActionController::Base ; end
 
       get '/posts?debug_assets=true'
-      assert_match(/<script src="\/assets\/application-([0-z]+)\.js\?body=1"><\/script>/, last_response.body)
-      assert_match(/<script src="\/assets\/xmlhr-([0-z]+)\.js\?body=1"><\/script>/, last_response.body)
+      assert_match(/<script src="\/assets\/application(\.debug)?-([0-z]+)\.js"><\/script>/, last_response.body)
     end
   end
 end
diff --git a/railties/test/application/assets_test.rb b/railties/test/application/assets_test.rb
index d58a27403e..dca5cf2e5b 100644
--- a/railties/test/application/assets_test.rb
+++ b/railties/test/application/assets_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require 'isolation/abstract_unit'
 require 'rack/test'
 require 'active_support/json'
@@ -18,22 +17,32 @@ module ApplicationTests
     end
 
     def precompile!(env = nil)
-      quietly do
-        precompile_task = "bundle exec rake assets:precompile #{env} --trace 2>&1"
-        output = Dir.chdir(app_path) { %x[ #{precompile_task} ] }
-        assert $?.success?, output
-        output
+      with_env env.to_h do
+        quietly do
+          precompile_task = "bin/rake assets:precompile --trace 2>&1"
+          output = Dir.chdir(app_path) { %x[ #{precompile_task} ] }
+          assert $?.success?, output
+          output
+        end
       end
     end
 
+    def with_env(env)
+      env.each { |k, v| ENV[k.to_s] = v }
+      yield
+    ensure
+      env.each_key { |k| ENV.delete k.to_s }
+    end
+
     def clean_assets!
       quietly do
-        assert Dir.chdir(app_path) { system('bundle exec rake assets:clobber') }
+        assert Dir.chdir(app_path) { system('bin/rake assets:clobber') }
       end
     end
 
     def assert_file_exists(filename)
-      assert Dir[filename].first, "missing #{filename}"
+      globbed = Dir[filename]
+      assert globbed.one?, "Found #{globbed.size} files matching #{filename}. All files in the directory: #{Dir.entries(File.dirname(filename)).inspect}"
     end
 
     def assert_no_file_exists(filename)
@@ -52,7 +61,10 @@ module ApplicationTests
 
       add_to_env_config "development", "config.assets.digest = false"
 
-      require "#{app_path}/config/environment"
+      # FIXME: shush Sass warning spam, not relevant to testing Railties
+      Kernel.silence_warnings do
+        require "#{app_path}/config/environment"
+      end
 
       get "/assets/demo.js"
       assert_equal 'a = "/assets/rails.png";', last_response.body.strip
@@ -61,9 +73,10 @@ module ApplicationTests
     test "assets do not require compressors until it is used" do
       app_file "app/assets/javascripts/demo.js.erb", "<%= :alert %>();"
       add_to_env_config "production", "config.assets.compile = true"
+      add_to_env_config "production", "config.assets.precompile = []"
 
-      ENV["RAILS_ENV"] = "production"
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "production"
 
       assert !defined?(Uglifier)
       get "/assets/demo.js"
@@ -72,10 +85,10 @@ module ApplicationTests
     end
 
     test "precompile creates the file, gives it the original asset's content and run in production as default" do
+      app_file "app/assets/config/manifest.js", "//= link_tree ../javascripts"
       app_file "app/assets/javascripts/application.js", "alert();"
       app_file "app/assets/javascripts/foo/application.js", "alert();"
 
-      ENV["RAILS_ENV"] = nil
       precompile!
 
       files = Dir["#{app_path}/public/assets/application-*.js"]
@@ -87,6 +100,7 @@ module ApplicationTests
     end
 
     def test_precompile_does_not_hit_the_database
+      app_file "app/assets/config/manifest.js", "//= link_tree ../javascripts"
       app_file "app/assets/javascripts/application.js", "alert();"
       app_file "app/assets/javascripts/foo/application.js", "alert();"
       app_file "app/controllers/users_controller.rb", <<-eoruby
@@ -96,10 +110,9 @@ module ApplicationTests
         class User < ActiveRecord::Base; raise 'should not be reached'; end
       eoruby
 
-      ENV['RAILS_ENV']  = 'production'
-      ENV['DATABASE_URL'] = 'postgresql://baduser:badpass@127.0.0.1/dbname'
-
-      precompile!
+      precompile! \
+        RAILS_ENV: 'production',
+        DATABASE_URL: 'postgresql://baduser:badpass@127.0.0.1/dbname'
 
       files = Dir["#{app_path}/public/assets/application-*.js"]
       files << Dir["#{app_path}/public/assets/foo/application-*.js"].first
@@ -107,9 +120,6 @@ module ApplicationTests
         assert_not_nil file, "Expected application.js asset to be generated, but none found"
         assert_equal "alert();".strip, File.read(file).strip
       end
-    ensure
-      ENV.delete 'RAILS_ENV'
-      ENV.delete 'DATABASE_URL'
     end
 
     test "precompile application.js and application.css and all other non JS/CSS files" do
@@ -169,34 +179,39 @@ module ApplicationTests
 
     test 'precompile use assets defined in app env config' do
       add_to_env_config 'production', 'config.assets.precompile = [ "something.js" ]'
-
       app_file 'app/assets/javascripts/something.js.erb', 'alert();'
 
-      precompile! 'RAILS_ENV=production'
+      precompile! RAILS_ENV: 'production'
 
       assert_file_exists("#{app_path}/public/assets/something-*.js")
     end
 
     test 'precompile use assets defined in app config and reassigned in app env config' do
-      add_to_config 'config.assets.precompile = [ "something.js" ]'
-      add_to_env_config 'production', 'config.assets.precompile += [ "another.js" ]'
+      add_to_config 'config.assets.precompile = [ "something_manifest.js" ]'
+      add_to_env_config 'production', 'config.assets.precompile += [ "another_manifest.js" ]'
+
+      app_file 'app/assets/config/something_manifest.js', '//= link something.js'
+      app_file 'app/assets/config/another_manifest.js', '//= link another.js'
 
       app_file 'app/assets/javascripts/something.js.erb', 'alert();'
       app_file 'app/assets/javascripts/another.js.erb', 'alert();'
 
-      precompile! 'RAILS_ENV=production'
+      precompile! RAILS_ENV: 'production'
 
+      assert_file_exists("#{app_path}/public/assets/something_manifest-*.js")
       assert_file_exists("#{app_path}/public/assets/something-*.js")
+      assert_file_exists("#{app_path}/public/assets/another_manifest-*.js")
       assert_file_exists("#{app_path}/public/assets/another-*.js")
     end
 
-    test "asset pipeline should use a Sprockets::Index when config.assets.digest is true" do
+    test "asset pipeline should use a Sprockets::CachedEnvironment when config.assets.digest is true" do
       add_to_config "config.action_controller.perform_caching = false"
+      add_to_env_config "production", "config.assets.compile = true"
 
-      ENV["RAILS_ENV"] = "production"
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "production"
 
-      assert_equal Sprockets::Index, Rails.application.assets.class
+      assert_equal Sprockets::CachedEnvironment, Rails.application.assets.class
     end
 
     test "precompile creates a manifest file with all the assets listed" do
@@ -205,8 +220,8 @@ module ApplicationTests
       app_file "app/assets/javascripts/application.js", "alert();"
 
       precompile!
-      manifest = Dir["#{app_path}/public/assets/manifest-*.json"].first
 
+      manifest = Dir["#{app_path}/public/assets/.sprockets-manifest-*.json"].first
       assets = ActiveSupport::JSON.decode(File.read(manifest))
       assert_match(/application-([0-z]+)\.js/, assets["assets"]["application.js"])
       assert_match(/application-([0-z]+)\.css/, assets["assets"]["application.css"])
@@ -218,7 +233,7 @@ module ApplicationTests
 
       precompile!
 
-      manifest = Dir["#{app_path}/public/x/manifest-*.json"].first
+      manifest = Dir["#{app_path}/public/x/.sprockets-manifest-*.json"].first
       assets = ActiveSupport::JSON.decode(File.read(manifest))
       assert_match(/application-([0-z]+)\.js/, assets["assets"]["application.js"])
     end
@@ -227,14 +242,14 @@ module ApplicationTests
       app_file "app/assets/javascripts/application.js", "alert();"
       add_to_env_config "production", "config.serve_static_files = true"
 
-      ENV["RAILS_ENV"] = "production"
-      precompile!
+      precompile! RAILS_ENV: 'production'
 
-      manifest = Dir["#{app_path}/public/assets/manifest-*.json"].first
+      manifest = Dir["#{app_path}/public/assets/.sprockets-manifest-*.json"].first
       assets = ActiveSupport::JSON.decode(File.read(manifest))
       asset_path = assets["assets"]["application.js"]
 
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "production"
 
       # Checking if Uglifier is defined we can know if Sprockets was reached or not
       assert !defined?(Uglifier)
@@ -243,12 +258,11 @@ module ApplicationTests
       assert !defined?(Uglifier)
     end
 
-    test "precompile properly refers files referenced with asset_path and runs in the provided RAILS_ENV" do
+    test "precompile properly refers files referenced with asset_path" do
       app_file "app/assets/images/rails.png", "notactuallyapng"
-      app_file "app/assets/stylesheets/application.css.erb", "<%= asset_path('rails.png') %>"
-      add_to_env_config "test", "config.assets.digest = true"
+      app_file "app/assets/stylesheets/application.css.erb", "p { background-image: url(<%= asset_path('rails.png') %>) }"
 
-      precompile!('RAILS_ENV=test')
+      precompile!
 
       file = Dir["#{app_path}/public/assets/application-*.css"].first
       assert_match(/\/assets\/rails-([0-z]+)\.png/, File.read(file))
@@ -257,29 +271,27 @@ module ApplicationTests
     test "precompile shouldn't use the digests present in manifest.json" do
       app_file "app/assets/images/rails.png", "notactuallyapng"
 
-      app_file "app/assets/stylesheets/application.css.erb", "p { url: <%= asset_path('rails.png') %> }"
+      app_file "app/assets/stylesheets/application.css.erb", "p { background-image: url(<%= asset_path('rails.png') %>) }"
 
-      ENV["RAILS_ENV"] = "production"
-      precompile!
+      precompile! RAILS_ENV: 'production'
 
-      manifest = Dir["#{app_path}/public/assets/manifest-*.json"].first
+      manifest = Dir["#{app_path}/public/assets/.sprockets-manifest-*.json"].first
       assets = ActiveSupport::JSON.decode(File.read(manifest))
       asset_path = assets["assets"]["application.css"]
 
       app_file "app/assets/images/rails.png", "p { url: change }"
 
       precompile!
-      assets = ActiveSupport::JSON.decode(File.read(manifest))
 
+      assets = ActiveSupport::JSON.decode(File.read(manifest))
       assert_not_equal asset_path, assets["assets"]["application.css"]
     end
 
     test "precompile appends the md5 hash to files referenced with asset_path and run in production with digest true" do
       app_file "app/assets/images/rails.png", "notactuallyapng"
-      app_file "app/assets/stylesheets/application.css.erb", "<%= asset_path('rails.png') %>"
+      app_file "app/assets/stylesheets/application.css.erb", "p { background-image: url(<%= asset_path('rails.png') %>) }"
 
-      ENV["RAILS_ENV"] = "production"
-      precompile!
+      precompile! RAILS_ENV: 'production'
 
       file = Dir["#{app_path}/public/assets/application-*.css"].first
       assert_match(/\/assets\/rails-([0-z]+)\.png/, File.read(file))
@@ -288,15 +300,17 @@ module ApplicationTests
     test "precompile should handle utf8 filenames" do
       filename = "レイルズ.png"
       app_file "app/assets/images/#{filename}", "not an image really"
-      add_to_config "config.assets.precompile = [ /\.png$/, /application.(css|js)$/ ]"
+      app_file "app/assets/config/manifest.js", "//= link_tree ../images"
+      add_to_config "config.assets.precompile = %w(manifest.js)"
 
       precompile!
 
-      manifest = Dir["#{app_path}/public/assets/manifest-*.json"].first
+      manifest = Dir["#{app_path}/public/assets/.sprockets-manifest-*.json"].first
       assets = ActiveSupport::JSON.decode(File.read(manifest))
       assert asset_path = assets["assets"].find { |(k, _)| k && k =~ /.png/ }[1]
 
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "development"
 
       get "/assets/#{URI.parser.escape(asset_path)}"
       assert_match "not an image really", last_response.body
@@ -319,8 +333,8 @@ module ApplicationTests
       app_file "app/assets/javascripts/demo.js.erb", "<%= :alert %>();"
       add_to_config "config.assets.compile = false"
 
-      ENV["RAILS_ENV"] = "production"
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "production"
 
       get "/assets/demo.js"
       assert_equal 404, last_response.status
@@ -337,7 +351,8 @@ module ApplicationTests
 
       add_to_env_config "development", "config.assets.digest = false"
 
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "development"
 
       class ::OmgController < ActionController::Base
         def index
@@ -363,7 +378,8 @@ module ApplicationTests
 
       add_to_env_config "development", "config.assets.digest = false"
 
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "development"
 
       get "/assets/demo.js"
       assert_match "alert();", last_response.body
@@ -374,10 +390,10 @@ module ApplicationTests
       app_with_assets_in_view
 
       # config.assets.debug and config.assets.compile are false for production environment
-      ENV["RAILS_ENV"] = "production"
-      precompile!
+      precompile! RAILS_ENV: 'production'
 
-      require "#{app_path}/config/environment"
+      # Load app env
+      app "production"
 
       class ::PostsController < ActionController::Base ; end
 
@@ -393,7 +409,8 @@ module ApplicationTests
       app_file "app/assets/javascripts/xmlhr.js.erb", "<%= Post.name %>"
 
       precompile!
-      assert_equal "Post;\n", File.read(Dir["#{app_path}/public/assets/application-*.js"].first)
+
+      assert_equal "Post\n;\n", File.read(Dir["#{app_path}/public/assets/application-*.js"].first)
     end
 
     test "initialization on the assets group should set assets_dir" do
@@ -434,13 +451,16 @@ module ApplicationTests
       app_with_assets_in_view
       add_to_config "config.asset_host = 'example.com'"
       add_to_env_config "development", "config.assets.digest = false"
-      require "#{app_path}/config/environment"
+
+      # Load app env
+      app "development"
+
       class ::PostsController < ActionController::Base; end
 
       get '/posts', {}, {'HTTPS'=>'off'}
-      assert_match('src="http://example.com/assets/application.js', last_response.body)
+      assert_match('src="http://example.com/assets/application.debug.js', last_response.body)
       get '/posts', {}, {'HTTPS'=>'on'}
-      assert_match('src="https://example.com/assets/application.js', last_response.body)
+      assert_match('src="https://example.com/assets/application.debug.js', last_response.body)
     end
 
     test "asset urls should be protocol-relative if no request is in scope" do
@@ -449,6 +469,7 @@ module ApplicationTests
       add_to_config "config.assets.precompile = %w{rails.png image_loader.js}"
       add_to_config "config.asset_host = 'example.com'"
       add_to_env_config "development", "config.assets.digest = false"
+
       precompile!
 
       assert_match "src='//example.com/assets/rails.png'", File.read(Dir["#{app_path}/public/assets/image_loader-*.js"].first)
@@ -460,20 +481,10 @@ module ApplicationTests
       app_file "app/assets/javascripts/app.js.erb", "var src='<%= image_path('rails.png') %>';"
       add_to_config "config.assets.precompile = %w{rails.png app.js}"
       add_to_env_config "development", "config.assets.digest = false"
-      precompile!
-
-      assert_match "src='/sub/uri/assets/rails.png'", File.read(Dir["#{app_path}/public/assets/app-*.js"].first)
-    end
 
-    test "assets:cache:clean should clean cache" do
-      ENV["RAILS_ENV"] = "production"
       precompile!
 
-      quietly do
-        Dir.chdir(app_path){ `bundle exec rake assets:clobber` }
-      end
-
-      assert !File.exist?("#{app_path}/tmp/cache/assets")
+      assert_match "src='/sub/uri/assets/rails.png'", File.read(Dir["#{app_path}/public/assets/app-*.js"].first)
     end
 
     private
diff --git a/railties/test/application/bin_setup_test.rb b/railties/test/application/bin_setup_test.rb
new file mode 100644
index 0000000000..1bdced02e9
--- /dev/null
+++ b/railties/test/application/bin_setup_test.rb
@@ -0,0 +1,54 @@
+require 'isolation/abstract_unit'
+
+module ApplicationTests
+  class BinSetupTest < ActiveSupport::TestCase
+    include ActiveSupport::Testing::Isolation
+
+    def setup
+      build_app
+    end
+
+    def teardown
+      teardown_app
+    end
+
+    def test_bin_setup
+      Dir.chdir(app_path) do
+        app_file 'db/schema.rb', <<-RUBY
+          ActiveRecord::Schema.define(version: 20140423102712) do
+            create_table(:articles) {}
+          end
+        RUBY
+
+        list_tables = lambda { `bin/rails runner 'p ActiveRecord::Base.connection.tables'`.strip }
+        File.write("log/my.log", "zomg!")
+
+        assert_equal '[]', list_tables.call
+        assert_equal 5, File.size("log/my.log")
+        assert_not File.exist?("tmp/restart.txt")
+        `bin/setup 2>&1`
+        assert_equal 0, File.size("log/my.log")
+        assert_equal '["articles", "schema_migrations"]', list_tables.call
+        assert File.exist?("tmp/restart.txt")
+      end
+    end
+
+    def test_bin_setup_output
+      Dir.chdir(app_path) do
+        app_file 'db/schema.rb', ""
+
+        output = `bin/setup 2>&1`
+        assert_equal(<<-OUTPUT, output)
+== Installing dependencies ==
+The Gemfile's dependencies are satisfied
+
+== Preparing database ==
+
+== Removing old logs and tempfiles ==
+
+== Restarting application server ==
+        OUTPUT
+      end
+    end
+  end
+end
diff --git a/railties/test/application/build_original_fullpath_test.rb b/railties/test/application/build_original_fullpath_test.rb
deleted file mode 100644
index 647ffb097a..0000000000
--- a/railties/test/application/build_original_fullpath_test.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require "abstract_unit"
-
-module ApplicationTests
-  class BuildOriginalPathTest < ActiveSupport::TestCase
-    def test_include_original_PATH_info_in_ORIGINAL_FULLPATH
-      env = { 'PATH_INFO' => '/foo/' }
-      assert_equal "/foo/", Rails.application.send(:build_original_fullpath, env)
-    end
-
-    def test_include_SCRIPT_NAME
-      env = {
-        'SCRIPT_NAME' => '/foo',
-        'PATH_INFO' => '/bar'
-      }
-
-      assert_equal "/foo/bar", Rails.application.send(:build_original_fullpath, env)
-    end
-
-    def test_include_QUERY_STRING
-      env = {
-        'PATH_INFO' => '/foo',
-        'QUERY_STRING' => 'bar',
-      }
-      assert_equal "/foo?bar", Rails.application.send(:build_original_fullpath, env)
-    end
-  end
-end
diff --git a/railties/test/application/configuration/base_test.rb b/railties/test/application/configuration/base_test.rb
deleted file mode 100644
index d6a82b139d..0000000000
--- a/railties/test/application/configuration/base_test.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
-require 'env_helpers'
-
-module ApplicationTests
-  module ConfigurationTests
-    class BaseTest < ActiveSupport::TestCase
-      def setup
-        build_app
-        boot_rails
-        FileUtils.rm_rf("#{app_path}/config/environments")
-      end
-
-      def teardown
-        teardown_app
-        FileUtils.rm_rf(new_app) if File.directory?(new_app)
-      end
-
-      private
-        def new_app
-          File.expand_path("#{app_path}/../new_app")
-        end
-
-        def copy_app
-          FileUtils.cp_r(app_path, new_app)
-        end
-
-        def app
-          @app ||= Rails.application
-        end
-
-        def require_environment
-          require "#{app_path}/config/environment"  
-        end
-    end
-  end
-end
\ No newline at end of file
diff --git a/railties/test/application/configuration/custom_test.rb b/railties/test/application/configuration/custom_test.rb
index f8d22f6d97..28b3b2f2d6 100644
--- a/railties/test/application/configuration/custom_test.rb
+++ b/railties/test/application/configuration/custom_test.rb
@@ -1,22 +1,54 @@
-require 'application/configuration/base_test'
-
-class ApplicationTests::ConfigurationTests::CustomTest < ApplicationTests::ConfigurationTests::BaseTest
-  test 'access custom configuration point' do
-    add_to_config <<-RUBY
-      config.x.payment_processing.schedule = :daily
-      config.x.payment_processing.retries  = 3
-      config.x.super_debugger              = true
-      config.x.hyper_debugger              = false
-      config.x.nil_debugger                = nil
-    RUBY
-    require_environment
-
-    x = Rails.configuration.x
-    assert_equal :daily, x.payment_processing.schedule
-    assert_equal 3, x.payment_processing.retries
-    assert_equal true, x.super_debugger
-    assert_equal false, x.hyper_debugger
-    assert_equal nil, x.nil_debugger
-    assert_nil x.i_do_not_exist.zomg
+require 'isolation/abstract_unit'
+
+module ApplicationTests
+  module ConfigurationTests
+    class CustomTest < ActiveSupport::TestCase
+      def setup
+        build_app
+        boot_rails
+        FileUtils.rm_rf("#{app_path}/config/environments")
+      end
+
+      def teardown
+        teardown_app
+        FileUtils.rm_rf(new_app) if File.directory?(new_app)
+      end
+
+      test 'access custom configuration point' do
+        add_to_config <<-RUBY
+          config.x.payment_processing.schedule = :daily
+          config.x.payment_processing.retries  = 3
+          config.x.super_debugger              = true
+          config.x.hyper_debugger              = false
+          config.x.nil_debugger                = nil
+        RUBY
+        require_environment
+
+        x = Rails.configuration.x
+        assert_equal :daily, x.payment_processing.schedule
+        assert_equal 3, x.payment_processing.retries
+        assert_equal true, x.super_debugger
+        assert_equal false, x.hyper_debugger
+        assert_equal nil, x.nil_debugger
+        assert_nil x.i_do_not_exist.zomg
+      end
+
+      private
+        def new_app
+          File.expand_path("#{app_path}/../new_app")
+        end
+
+        def copy_app
+          FileUtils.cp_r(app_path, new_app)
+        end
+
+        def app
+          @app ||= Rails.application
+        end
+
+        def require_environment
+          require "#{app_path}/config/environment"
+        end
+    end
   end
 end
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index 8f5b2d0d68..ebcfcb1c3a 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -34,8 +34,19 @@ module ApplicationTests
       FileUtils.cp_r(app_path, new_app)
     end
 
-    def app
-      @app ||= Rails.application
+    def app(env = 'development')
+      @app ||= begin
+        ENV['RAILS_ENV'] = env
+
+        # FIXME: shush Sass warning spam, not relevant to testing Railties
+        Kernel.silence_warnings do
+          require "#{app_path}/config/environment"
+        end
+
+        Rails.application
+      ensure
+        ENV.delete 'RAILS_ENV'
+      end
     end
 
     def setup
@@ -78,7 +89,9 @@ module ApplicationTests
         require 'my_logger'
         config.logger = MyLogger.new STDOUT
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
+
       assert_equal 'MyLogger', Rails.application.config.logger.class.name
     end
 
@@ -97,7 +110,7 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       ActiveRecord::Migrator.migrations_paths = ["#{app_path}/db/migrate"]
 
@@ -128,29 +141,29 @@ module ApplicationTests
     test "Rails.application is nil until app is initialized" do
       require 'rails'
       assert_nil Rails.application
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_equal AppTemplate::Application.instance, Rails.application
     end
 
     test "Rails.application responds to all instance methods" do
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_respond_to Rails.application, :routes_reloader
       assert_equal Rails.application.routes_reloader, AppTemplate::Application.routes_reloader
     end
 
     test "Rails::Application responds to paths" do
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_respond_to AppTemplate::Application, :paths
       assert_equal ["#{app_path}/app/views"], AppTemplate::Application.paths["app/views"].expanded
     end
 
     test "the application root is set correctly" do
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_equal Pathname.new(app_path), Rails.application.root
     end
 
     test "the application root can be seen from the application singleton" do
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_equal Pathname.new(app_path), AppTemplate::Application.root
     end
 
@@ -162,7 +175,8 @@ module ApplicationTests
 
       use_frameworks []
 
-      require "#{app_path}/config/environment"
+      app 'development'
+
       assert_equal Pathname.new(new_app), Rails.application.root
     end
 
@@ -172,7 +186,7 @@ module ApplicationTests
       use_frameworks []
 
       Dir.chdir("#{app_path}") do
-        require "#{app_path}/config/environment"
+        app 'development'
         assert_equal Pathname.new("#{app_path}"), Rails.application.root
       end
     end
@@ -181,7 +195,9 @@ module ApplicationTests
       add_to_config <<-RUBY
         config.root = "#{app_path}"
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
+
       assert_instance_of Pathname, Rails.root
     end
 
@@ -189,7 +205,9 @@ module ApplicationTests
       add_to_config <<-RUBY
         config.paths["public"] = "somewhere"
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
+
       assert_instance_of Pathname, Rails.public_path
     end
 
@@ -199,12 +217,13 @@ module ApplicationTests
         config.cache_classes = true
       RUBY
 
-      require "#{app_path}/config/application"
-      assert Rails.application.initialize!
+      app 'development'
+
+      assert_equal :require, ActiveSupport::Dependencies.mechanism
     end
 
     test "application is always added to eager_load namespaces" do
-      require "#{app_path}/config/application"
+      app 'development'
       assert_includes Rails.application.config.eager_load_namespaces, AppTemplate::Application
     end
 
@@ -218,7 +237,7 @@ module ApplicationTests
       use_frameworks []
 
       assert_nothing_raised do
-        require "#{app_path}/config/application"
+        app 'development'
       end
     end
 
@@ -230,7 +249,7 @@ module ApplicationTests
       RUBY
 
       assert_nothing_raised do
-        require "#{app_path}/config/application"
+        app 'development'
       end
     end
 
@@ -239,7 +258,7 @@ module ApplicationTests
         Rails.application.config.filter_parameters += [ :password, :foo, 'bar' ]
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_equal [:password, :foo, 'bar'], Rails.application.env_config['action_dispatch.parameter_filter']
     end
@@ -255,7 +274,7 @@ module ApplicationTests
 
       assert !$prepared
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       get "/"
       assert $prepared
@@ -267,7 +286,7 @@ module ApplicationTests
     end
 
     test "skipping config.encoding still results in 'utf-8' as the default" do
-      require "#{app_path}/config/application"
+      app 'development'
       assert_utf8
     end
 
@@ -276,7 +295,7 @@ module ApplicationTests
         config.encoding = "utf-8"
       RUBY
 
-      require "#{app_path}/config/application"
+      app 'development'
       assert_utf8
     end
 
@@ -285,7 +304,7 @@ module ApplicationTests
         config.paths["public"] = "somewhere"
       RUBY
 
-      require "#{app_path}/config/application"
+      app 'development'
       assert_equal Pathname.new(app_path).join("somewhere"), Rails.public_path
     end
 
@@ -293,7 +312,7 @@ module ApplicationTests
       restore_default_config
 
       with_rails_env "production" do
-        require "#{app_path}/config/environment"
+        app 'production'
         assert_not app.config.serve_static_files
       end
     end
@@ -303,7 +322,7 @@ module ApplicationTests
 
       with_rails_env "production" do
         switch_env "RAILS_SERVE_STATIC_FILES", "1" do
-          require "#{app_path}/config/environment"
+          app 'production'
           assert app.config.serve_static_files
         end
       end
@@ -314,12 +333,22 @@ module ApplicationTests
 
       with_rails_env "production" do
         switch_env "RAILS_SERVE_STATIC_FILES", " " do
-          require "#{app_path}/config/environment"
+          app 'production'
           assert_not app.config.serve_static_files
         end
       end
     end
 
+    test "config.static_cache_control is deprecated" do
+      make_basic_app do |application|
+        assert_deprecated do
+          application.config.static_cache_control = "public, max-age=60"
+        end
+
+        assert_equal application.config.static_cache_control, "public, max-age=60"
+      end
+    end
+
     test "Use key_generator when secret_key_base is set" do
       make_basic_app do |application|
         application.secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
@@ -363,8 +392,8 @@ module ApplicationTests
         development:
           secret_key_base:
       YAML
-      require "#{app_path}/config/environment"
 
+      app 'development'
 
       assert_equal app.env_config['action_dispatch.key_generator'], Rails.application.key_generator
       assert_equal app.env_config['action_dispatch.key_generator'].class, ActiveSupport::LegacyKeyGenerator
@@ -380,13 +409,27 @@ module ApplicationTests
         development:
           secret_key_base:
       YAML
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_deprecated(/You didn't set `secret_key_base`./) do
         app.env_config
       end
     end
 
+    test "raise when secrets.secret_key_base is not a type of string" do
+      app_file 'config/secrets.yml', <<-YAML
+        development:
+          secret_key_base: 123
+      YAML
+
+      app 'development'
+
+      assert_raise(ArgumentError) do
+        app.key_generator
+      end
+    end
+
     test "prefer secrets.secret_token over config.secret_token" do
       app_file 'config/initializers/secret_token.rb', <<-RUBY
         Rails.application.config.secret_token = ""
@@ -395,7 +438,8 @@ module ApplicationTests
         development:
           secret_token: 3b7cd727ee24e8444053437c36cc66c3
       YAML
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_equal '3b7cd727ee24e8444053437c36cc66c3', app.secrets.secret_token
     end
@@ -426,7 +470,7 @@ module ApplicationTests
           secret_key_base: 3b7cd727ee24e8444053437c36cc66c3
       YAML
 
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_equal '3b7cd727ee24e8444053437c36cc66c3', app.secrets.secret_key_base
     end
 
@@ -436,7 +480,7 @@ module ApplicationTests
         Rails.application.config.secret_key_base = "3b7cd727ee24e8444053437c36cc66c3"
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_equal '3b7cd727ee24e8444053437c36cc66c3', app.secrets.secret_key_base
     end
 
@@ -449,7 +493,8 @@ module ApplicationTests
           secret_key_base:
           secret_token:
       YAML
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_equal 'b3c631c314c0bbca50c1b2843150fe33', app.secrets.secret_token
       assert_equal 'b3c631c314c0bbca50c1b2843150fe33', app.config.secret_token
@@ -463,7 +508,8 @@ module ApplicationTests
           aws_secret_access_key: myamazonsecretaccesskey
       YAML
 
-      require "#{app_path}/config/environment"
+      app 'development'
+
       assert_equal 'myamazonaccesskeyid', app.secrets.aws_access_key_id
       assert_equal 'myamazonsecretaccesskey', app.secrets.aws_secret_access_key
     end
@@ -471,7 +517,8 @@ module ApplicationTests
     test "blank config/secrets.yml does not crash the loading process" do
       app_file 'config/secrets.yml', <<-YAML
       YAML
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_nil app.secrets.not_defined
     end
@@ -484,7 +531,8 @@ module ApplicationTests
         development:
           secret_key_base:
       YAML
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_equal "iaminallyoursecretkeybase", app.secrets.secret_key_base
     end
@@ -497,7 +545,8 @@ module ApplicationTests
         development:
           secret_key_base:
       YAML
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_equal 'b3c631c314c0bbca50c1b2843150fe33', app.config.secret_token
       assert_equal nil, app.secrets.secret_key_base
@@ -512,7 +561,8 @@ module ApplicationTests
         development:
           secret_key_base:
       YAML
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_equal '', app.config.secret_token
       assert_equal nil, app.secrets.secret_key_base
@@ -535,7 +585,6 @@ module ApplicationTests
     end
 
     test "default form builder specified as a string" do
-
       app_file 'config/initializers/form_builder.rb', <<-RUBY
       class CustomFormBuilder < ActionView::Helpers::FormBuilder
         def text_field(attribute, *args)
@@ -567,7 +616,7 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       get "/posts"
       assert_match(/label/, last_response.body)
@@ -606,9 +655,9 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
-      params = {authenticity_token: token}
+      params = { authenticity_token: token }
 
       get "/posts/1"
       assert_match(/patch/, last_response.body)
@@ -659,9 +708,9 @@ module ApplicationTests
         config.action_mailer.interceptors = MyMailInterceptor
       RUBY
 
-      require "#{app_path}/config/environment"
-      require "mail"
+      app 'development'
 
+      require "mail"
       _ = ActionMailer::Base
 
       assert_equal [::MyMailInterceptor], ::Mail.send(:class_variable_get, "@@delivery_interceptors")
@@ -672,9 +721,9 @@ module ApplicationTests
         config.action_mailer.interceptors = [MyMailInterceptor, "MyOtherMailInterceptor"]
       RUBY
 
-      require "#{app_path}/config/environment"
-      require "mail"
+      app 'development'
 
+      require "mail"
       _ = ActionMailer::Base
 
       assert_equal [::MyMailInterceptor, ::MyOtherMailInterceptor], ::Mail.send(:class_variable_get, "@@delivery_interceptors")
@@ -685,12 +734,12 @@ module ApplicationTests
         config.action_mailer.preview_interceptors = MyPreviewMailInterceptor
       RUBY
 
-      require "#{app_path}/config/environment"
-      require "mail"
+      app 'development'
 
+      require "mail"
       _ = ActionMailer::Base
 
-      assert_equal [::MyPreviewMailInterceptor], ActionMailer::Base.preview_interceptors
+      assert_equal [ActionMailer::InlinePreviewInterceptor, ::MyPreviewMailInterceptor], ActionMailer::Base.preview_interceptors
     end
 
     test "registers multiple preview interceptors with ActionMailer" do
@@ -698,12 +747,25 @@ module ApplicationTests
         config.action_mailer.preview_interceptors = [MyPreviewMailInterceptor, "MyOtherPreviewMailInterceptor"]
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
+
       require "mail"
+      _ = ActionMailer::Base
+
+      assert_equal [ActionMailer::InlinePreviewInterceptor, MyPreviewMailInterceptor, MyOtherPreviewMailInterceptor], ActionMailer::Base.preview_interceptors
+    end
+
+    test "default preview interceptor can be removed" do
+      app_file 'config/initializers/preview_interceptors.rb', <<-RUBY
+        ActionMailer::Base.preview_interceptors.delete(ActionMailer::InlinePreviewInterceptor)
+      RUBY
 
+      app 'development'
+
+      require "mail"
       _ = ActionMailer::Base
 
-      assert_equal [MyPreviewMailInterceptor, MyOtherPreviewMailInterceptor], ActionMailer::Base.preview_interceptors
+      assert_equal [], ActionMailer::Base.preview_interceptors
     end
 
     test "registers observers with ActionMailer" do
@@ -711,9 +773,9 @@ module ApplicationTests
         config.action_mailer.observers = MyMailObserver
       RUBY
 
-      require "#{app_path}/config/environment"
-      require "mail"
+      app 'development'
 
+      require "mail"
       _ = ActionMailer::Base
 
       assert_equal [::MyMailObserver], ::Mail.send(:class_variable_get, "@@delivery_notification_observers")
@@ -724,21 +786,34 @@ module ApplicationTests
         config.action_mailer.observers = [MyMailObserver, "MyOtherMailObserver"]
       RUBY
 
-      require "#{app_path}/config/environment"
-      require "mail"
+      app 'development'
 
+      require "mail"
       _ = ActionMailer::Base
 
       assert_equal [::MyMailObserver, ::MyOtherMailObserver], ::Mail.send(:class_variable_get, "@@delivery_notification_observers")
     end
 
+    test "allows setting the queue name for the ActionMailer::DeliveryJob" do
+      add_to_config <<-RUBY
+        config.action_mailer.deliver_later_queue_name = 'test_default'
+      RUBY
+
+      app 'development'
+
+      require "mail"
+      _ = ActionMailer::Base
+
+      assert_equal 'test_default', ActionMailer::Base.send(:class_variable_get, "@@deliver_later_queue_name")
+    end
+
     test "valid timezone is setup correctly" do
       add_to_config <<-RUBY
         config.root = "#{app_path}"
         config.time_zone = "Wellington"
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_equal "Wellington", Rails.application.config.time_zone
     end
@@ -750,7 +825,7 @@ module ApplicationTests
       RUBY
 
       assert_raise(ArgumentError) do
-        require "#{app_path}/config/environment"
+        app 'development'
       end
     end
 
@@ -760,7 +835,7 @@ module ApplicationTests
         config.beginning_of_week = :wednesday
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_equal :wednesday, Rails.application.config.beginning_of_week
     end
@@ -772,13 +847,14 @@ module ApplicationTests
       RUBY
 
       assert_raise(ArgumentError) do
-        require "#{app_path}/config/environment"
+        app 'development'
       end
     end
 
     test "config.action_view.cache_template_loading with cache_classes default" do
       add_to_config "config.cache_classes = true"
-      require "#{app_path}/config/environment"
+
+      app 'development'
       require 'action_view/base'
 
       assert_equal true, ActionView::Resolver.caching?
@@ -786,7 +862,8 @@ module ApplicationTests
 
     test "config.action_view.cache_template_loading without cache_classes default" do
       add_to_config "config.cache_classes = false"
-      require "#{app_path}/config/environment"
+
+      app 'development'
       require 'action_view/base'
 
       assert_equal false, ActionView::Resolver.caching?
@@ -797,7 +874,8 @@ module ApplicationTests
         config.cache_classes = true
         config.action_view.cache_template_loading = false
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
       require 'action_view/base'
 
       assert_equal false, ActionView::Resolver.caching?
@@ -808,7 +886,8 @@ module ApplicationTests
         config.cache_classes = false
         config.action_view.cache_template_loading = true
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
       require 'action_view/base'
 
       assert_equal true, ActionView::Resolver.caching?
@@ -823,7 +902,7 @@ module ApplicationTests
       require 'action_view/railtie'
       require 'action_view/base'
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_equal false, ActionView::Resolver.caching?
     end
@@ -876,7 +955,7 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       post "/posts.json", '{ "title": "foo", "name": "bar" }', "CONTENT_TYPE" => "application/json"
       assert_equal '{"title"=>"foo"}', last_response.body
@@ -898,7 +977,7 @@ module ApplicationTests
         config.action_controller.permit_all_parameters = true
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       post "/posts", {post: {"title" =>"zomg"}}
       assert_equal 'permitted', last_response.body
@@ -920,7 +999,7 @@ module ApplicationTests
         config.action_controller.action_on_unpermitted_parameters = :raise
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_equal :raise, ActionController::Parameters.action_on_unpermitted_parameters
 
@@ -929,7 +1008,7 @@ module ApplicationTests
     end
 
     test "config.action_controller.always_permitted_parameters are: controller, action by default" do
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_equal %w(controller action), ActionController::Parameters.always_permitted_parameters
     end
 
@@ -937,7 +1016,9 @@ module ApplicationTests
       add_to_config <<-RUBY
         config.action_controller.always_permitted_parameters = %w( controller action format )
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
+
       assert_equal %w( controller action format ), ActionController::Parameters.always_permitted_parameters
     end
 
@@ -958,7 +1039,7 @@ module ApplicationTests
         config.action_controller.action_on_unpermitted_parameters = :raise
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_equal :raise, ActionController::Parameters.action_on_unpermitted_parameters
 
@@ -967,25 +1048,19 @@ module ApplicationTests
     end
 
     test "config.action_controller.action_on_unpermitted_parameters is :log by default on development" do
-      ENV["RAILS_ENV"] = "development"
-
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_equal :log, ActionController::Parameters.action_on_unpermitted_parameters
     end
 
     test "config.action_controller.action_on_unpermitted_parameters is :log by default on test" do
-      ENV["RAILS_ENV"] = "test"
-
-      require "#{app_path}/config/environment"
+      app 'test'
 
       assert_equal :log, ActionController::Parameters.action_on_unpermitted_parameters
     end
 
     test "config.action_controller.action_on_unpermitted_parameters is false by default on production" do
-      ENV["RAILS_ENV"] = "production"
-
-      require "#{app_path}/config/environment"
+      app 'production'
 
       assert_equal false, ActionController::Parameters.action_on_unpermitted_parameters
     end
@@ -1063,17 +1138,14 @@ module ApplicationTests
 
     test "config.active_record.dump_schema_after_migration is false on production" do
       build_app
-      ENV["RAILS_ENV"] = "production"
 
-      require "#{app_path}/config/environment"
+      app 'production'
 
       assert_not ActiveRecord::Base.dump_schema_after_migration
     end
 
     test "config.active_record.dump_schema_after_migration is true by default on development" do
-      ENV["RAILS_ENV"] = "development"
-
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert ActiveRecord::Base.dump_schema_after_migration
     end
@@ -1099,7 +1171,7 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_not Rails.configuration.ran_block
 
       require 'rake'
@@ -1121,7 +1193,7 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_not Rails.configuration.ran_block
 
       Rails.application.load_generators
@@ -1139,7 +1211,7 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_not Rails.configuration.ran_block
 
       Rails.application.load_console
@@ -1157,7 +1229,7 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
       assert_not Rails.configuration.ran_block
 
       Rails.application.load_runner
@@ -1173,14 +1245,14 @@ module ApplicationTests
         end
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_kind_of Hash, Rails.application.config.database_configuration
     end
 
     test 'raises with proper error message if no database configuration found' do
       FileUtils.rm("#{app_path}/config/database.yml")
-      require "#{app_path}/config/environment"
+      app 'development'
       err = assert_raises RuntimeError do
         Rails.application.config.database_configuration
       end
@@ -1188,25 +1260,23 @@ module ApplicationTests
     end
 
     test 'config.action_mailer.show_previews defaults to true in development' do
-      Rails.env = "development"
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert Rails.application.config.action_mailer.show_previews
     end
 
     test 'config.action_mailer.show_previews defaults to false in production' do
-      Rails.env = "production"
-      require "#{app_path}/config/environment"
+      app 'production'
 
       assert_equal false, Rails.application.config.action_mailer.show_previews
     end
 
     test 'config.action_mailer.show_previews can be set in the configuration file' do
-      Rails.env = "production"
       add_to_config <<-RUBY
         config.action_mailer.show_previews = true
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'production'
 
       assert_equal true, Rails.application.config.action_mailer.show_previews
     end
@@ -1221,7 +1291,7 @@ module ApplicationTests
         config.my_custom_config = config_for('custom')
       RUBY
 
-      require "#{app_path}/config/environment"
+      app 'development'
 
       assert_equal 'custom key', Rails.application.config.my_custom_config['key']
     end
@@ -1232,7 +1302,7 @@ module ApplicationTests
       RUBY
 
       exception = assert_raises(RuntimeError) do
-        require "#{app_path}/config/environment"
+        app 'development'
       end
 
       assert_equal "Could not load configuration. No such file - #{app_path}/config/custom.yml", exception.message
@@ -1247,7 +1317,8 @@ module ApplicationTests
       add_to_config <<-RUBY
         config.my_custom_config = config_for('custom')
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_equal({}, Rails.application.config.my_custom_config)
     end
@@ -1259,7 +1330,8 @@ module ApplicationTests
       add_to_config <<-RUBY
         config.my_custom_config = config_for('custom')
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_equal({}, Rails.application.config.my_custom_config)
     end
@@ -1273,12 +1345,13 @@ module ApplicationTests
       add_to_config <<-RUBY
         config.my_custom_config = config_for('custom')
       RUBY
-      require "#{app_path}/config/environment"
+
+      app 'development'
 
       assert_equal 'custom key', Rails.application.config.my_custom_config['key']
     end
 
-    test "config_for with syntax error show a more descritive exception" do
+    test "config_for with syntax error show a more descriptive exception" do
       app_file 'config/custom.yml', <<-RUBY
       development:
         key: foo:
@@ -1289,7 +1362,7 @@ module ApplicationTests
       RUBY
 
       exception = assert_raises(RuntimeError) do
-        require "#{app_path}/config/environment"
+        app 'development'
       end
 
       assert_match 'YAML syntax error occurred while parsing', exception.message
diff --git a/railties/test/application/console_test.rb b/railties/test/application/console_test.rb
index 31bc003dcb..7bf123d12b 100644
--- a/railties/test/application/console_test.rb
+++ b/railties/test/application/console_test.rb
@@ -29,6 +29,18 @@ class ConsoleTest < ActiveSupport::TestCase
     assert_instance_of ActionDispatch::Integration::Session, console_session
   end
 
+  def test_app_can_access_path_helper_method
+    app_file 'config/routes.rb', <<-RUBY
+      Rails.application.routes.draw do
+        get 'foo', to: 'foo#index'
+      end
+    RUBY
+
+    load_environment
+    console_session = irb_context.app
+    assert_equal '/foo', console_session.foo_path
+  end
+
   def test_new_session_should_return_integration_session
     load_environment
     session = irb_context.new_session
diff --git a/railties/test/application/generators_test.rb b/railties/test/application/generators_test.rb
index 78ada58ec8..84cc6e120b 100644
--- a/railties/test/application/generators_test.rb
+++ b/railties/test/application/generators_test.rb
@@ -125,5 +125,40 @@ module ApplicationTests
         assert_equal expected, c.generators.options
       end
     end
+
+    test "api only generators hide assets, helper, js and css namespaces and set api option" do
+      add_to_config <<-RUBY
+        config.api_only = true
+      RUBY
+
+      # Initialize the application
+      require "#{app_path}/config/environment"
+      Rails.application.load_generators
+
+      assert Rails::Generators.hidden_namespaces.include?("assets")
+      assert Rails::Generators.hidden_namespaces.include?("helper")
+      assert Rails::Generators.hidden_namespaces.include?("js")
+      assert Rails::Generators.hidden_namespaces.include?("css")
+      assert Rails::Generators.options[:rails][:api]
+      assert_equal false, Rails::Generators.options[:rails][:assets]
+      assert_equal false, Rails::Generators.options[:rails][:helper]
+      assert_nil Rails::Generators.options[:rails][:template_engine]
+    end
+
+    test "api only generators allow overriding generator options" do
+      add_to_config <<-RUBY
+      config.generators.helper = true
+      config.api_only = true
+      config.generators.template_engine = :my_template
+      RUBY
+
+      # Initialize the application
+      require "#{app_path}/config/environment"
+      Rails.application.load_generators
+
+      assert Rails::Generators.options[:rails][:api]
+      assert Rails::Generators.options[:rails][:helper]
+      assert_equal :my_template, Rails::Generators.options[:rails][:template_engine]
+    end
   end
 end
diff --git a/railties/test/application/initializers/frameworks_test.rb b/railties/test/application/initializers/frameworks_test.rb
index 97b51911d9..13f3250f5b 100644
--- a/railties/test/application/initializers/frameworks_test.rb
+++ b/railties/test/application/initializers/frameworks_test.rb
@@ -1,5 +1,4 @@
 require "isolation/abstract_unit"
-require 'set'
 
 module ApplicationTests
   class FrameworksTest < ActiveSupport::TestCase
@@ -50,6 +49,17 @@ module ApplicationTests
       assert_equal "test.rails", ActionMailer::Base.default_url_options[:host]
     end
 
+    test "Default to HTTPS for ActionMailer URLs when force_ssl is on" do
+      app_file "config/environments/development.rb", <<-RUBY
+        Rails.application.configure do
+          config.force_ssl = true
+        end
+      RUBY
+
+      require "#{app_path}/config/environment"
+      assert_equal "https", ActionMailer::Base.default_url_options[:protocol]
+    end
+
     test "includes url helpers as action methods" do
       app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
@@ -129,6 +139,35 @@ module ApplicationTests
       assert_equal "false", last_response.body
     end
 
+    test "action_controller api executes using all the middleware stack" do
+      add_to_config "config.api_only = true"
+
+      app_file "app/controllers/application_controller.rb", <<-RUBY
+        class ApplicationController < ActionController::API
+        end
+      RUBY
+
+      app_file "app/controllers/omg_controller.rb", <<-RUBY
+        class OmgController < ApplicationController
+          def show
+            render json: { omg: 'omg' }
+          end
+        end
+      RUBY
+
+      app_file "config/routes.rb", <<-RUBY
+        Rails.application.routes.draw do
+          get "/:controller(/:action)"
+        end
+      RUBY
+
+      require 'rack/test'
+      extend Rack::Test::Methods
+
+      get 'omg/show'
+      assert_equal '{"omg":"omg"}', last_response.body
+    end
+
     # AD
     test "action_dispatch extensions are applied to ActionDispatch" do
       add_to_config "config.action_dispatch.tld_length = 2"
@@ -177,7 +216,7 @@ module ApplicationTests
     test "use schema cache dump" do
       Dir.chdir(app_path) do
         `rails generate model post title:string;
-         bundle exec rake db:migrate db:schema:cache:dump`
+         bin/rake db:migrate db:schema:cache:dump`
       end
       require "#{app_path}/config/environment"
       ActiveRecord::Base.connection.drop_table("posts") # force drop posts table for test.
@@ -187,7 +226,7 @@ module ApplicationTests
     test "expire schema cache dump" do
       Dir.chdir(app_path) do
         `rails generate model post title:string;
-         bundle exec rake db:migrate db:schema:cache:dump db:rollback`
+         bin/rake db:migrate db:schema:cache:dump db:rollback`
       end
       silence_warnings {
         require "#{app_path}/config/environment"
diff --git a/railties/test/application/initializers/i18n_test.rb b/railties/test/application/initializers/i18n_test.rb
index 9ee54796a4..ab7f29b0f2 100644
--- a/railties/test/application/initializers/i18n_test.rb
+++ b/railties/test/application/initializers/i18n_test.rb
@@ -132,6 +132,79 @@ en:
       assert_equal "2", last_response.body
     end
 
+    test "new locale files are loaded" do
+      add_to_config <<-RUBY
+        config.cache_classes = false
+      RUBY
+
+      app_file "config/locales/en.yml", <<-YAML
+en:
+  foo: "1"
+      YAML
+
+      app_file 'config/routes.rb', <<-RUBY
+        Rails.application.routes.draw do
+          get '/i18n',   :to => lambda { |env| [200, {}, [I18n.t(:foo)]] }
+        end
+      RUBY
+
+      require 'rack/test'
+      extend Rack::Test::Methods
+      load_app
+
+      get "/i18n"
+      assert_equal "1", last_response.body
+
+      # Wait a full second so we have time for changes to propagate
+      sleep(1)
+
+      remove_file "config/locales/en.yml"
+      app_file "config/locales/custom.en.yml", <<-YAML
+en:
+  foo: "2"
+      YAML
+
+      get "/i18n"
+      assert_equal "2", last_response.body
+    end
+
+    test "I18n.load_path is reloaded" do
+      add_to_config <<-RUBY
+        config.cache_classes = false
+      RUBY
+
+      app_file "config/locales/en.yml", <<-YAML
+en:
+  foo: "1"
+      YAML
+
+      app_file 'config/routes.rb', <<-RUBY
+        Rails.application.routes.draw do
+          get '/i18n',   :to => lambda { |env| [200, {}, [I18n.load_path.inspect]] }
+        end
+      RUBY
+
+      require 'rack/test'
+      extend Rack::Test::Methods
+      load_app
+
+      get "/i18n"
+
+      assert_match "en.yml", last_response.body
+
+      # Wait a full second so we have time for changes to propagate
+      sleep(1)
+
+      app_file "config/locales/fr.yml", <<-YAML
+fr:
+  foo: "2"
+      YAML
+
+      get "/i18n"
+      assert_match "fr.yml", last_response.body
+      assert_match "en.yml", last_response.body
+    end
+
     # Fallbacks
     test "not using config.i18n.fallbacks does not initialize I18n.fallbacks" do
       I18n.backend = Class.new(I18n::Backend::Simple).new
diff --git a/railties/test/application/loading_test.rb b/railties/test/application/loading_test.rb
index 85066210f3..1027bca2c1 100644
--- a/railties/test/application/loading_test.rb
+++ b/railties/test/application/loading_test.rb
@@ -210,7 +210,7 @@ class LoadingTest < ActiveSupport::TestCase
     app_file 'config/routes.rb', <<-RUBY
       $counter ||= 0
       Rails.application.routes.draw do
-        get '/c', to: lambda { |env| User; [200, {"Content-Type" => "text/plain"}, [$counter.to_s]] }
+        get '/c', to: lambda { |env| User.name; [200, {"Content-Type" => "text/plain"}, [$counter.to_s]] }
       end
     RUBY
 
@@ -243,7 +243,7 @@ class LoadingTest < ActiveSupport::TestCase
       $counter ||= 1
       $counter  *= 2
       Rails.application.routes.draw do
-        get '/c', to: lambda { |env| User; [200, {"Content-Type" => "text/plain"}, [$counter.to_s]] }
+        get '/c', to: lambda { |env| User.name; [200, {"Content-Type" => "text/plain"}, [$counter.to_s]] }
       end
     RUBY
 
diff --git a/railties/test/application/mailer_previews_test.rb b/railties/test/application/mailer_previews_test.rb
index 1752a9f3c6..643d876a26 100644
--- a/railties/test/application/mailer_previews_test.rb
+++ b/railties/test/application/mailer_previews_test.rb
@@ -1,5 +1,7 @@
 require 'isolation/abstract_unit'
 require 'rack/test'
+require 'base64'
+
 module ApplicationTests
   class MailerPreviewsTest < ActiveSupport::TestCase
     include ActiveSupport::Testing::Isolation
@@ -29,7 +31,7 @@ module ApplicationTests
     test "/rails/mailers is accessible with correct configuraiton" do
       add_to_config "config.action_mailer.show_previews = true"
       app("production")
-      get "/rails/mailers"
+      get "/rails/mailers", {}, {"REMOTE_ADDR" => "4.2.42.42"}
       assert_equal 200, last_response.status
     end
 
@@ -327,6 +329,32 @@ module ApplicationTests
       assert_match "Email &#39;bar&#39; not found in NotifierPreview", last_response.body
     end
 
+    test "mailer preview NullMail" do
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            # does not call +mail+
+          end
+        end
+      RUBY
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      app('development')
+
+      get "/rails/mailers/notifier/foo"
+      assert_match "You are trying to preview an email that does not have any content.", last_response.body
+      assert_match "notifier#foo", last_response.body
+    end
+
     test "mailer preview email part not found" do
       mailer 'notifier', <<-RUBY
         class Notifier < ActionMailer::Base
@@ -428,6 +456,222 @@ module ApplicationTests
       assert_match '<option selected value="?part=text%2Fplain">View as plain-text email</option>', last_response.body
     end
 
+    test "mailer previews create correct links when loaded on a subdirectory" do
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            mail to: "to@example.org"
+          end
+        end
+      RUBY
+
+      text_template 'notifier/foo', <<-RUBY
+        Hello, World!
+      RUBY
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      app('development')
+
+      get "/rails/mailers", {}, 'SCRIPT_NAME' => '/my_app'
+      assert_match '<h3><a href="/my_app/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+      assert_match '<li><a href="/my_app/rails/mailers/notifier/foo">foo</a></li>', last_response.body
+    end
+
+    test "plain text mailer preview with attachment" do
+      image_file "pixel.png", "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEWzIioca/JlAAAACklEQVQI12NgAAAAAgAB4iG8MwAAAABJRU5ErkJgggo="
+
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            attachments['pixel.png'] = File.read("#{app_path}/public/images/pixel.png", mode: 'rb')
+            mail to: "to@example.org"
+          end
+        end
+      RUBY
+
+      text_template 'notifier/foo', <<-RUBY
+        Hello, World!
+      RUBY
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      app('development')
+
+      get "/rails/mailers/notifier/foo"
+      assert_equal 200, last_response.status
+      assert_match %r[<iframe seamless name="messageBody"], last_response.body
+
+      get "/rails/mailers/notifier/foo?part=text/plain"
+      assert_equal 200, last_response.status
+      assert_match %r[Hello, World!], last_response.body
+    end
+
+    test "multipart mailer preview with attachment" do
+      image_file "pixel.png", "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEWzIioca/JlAAAACklEQVQI12NgAAAAAgAB4iG8MwAAAABJRU5ErkJgggo="
+
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            attachments['pixel.png'] = File.read("#{app_path}/public/images/pixel.png", mode: 'rb')
+            mail to: "to@example.org"
+          end
+        end
+      RUBY
+
+      text_template 'notifier/foo', <<-RUBY
+        Hello, World!
+      RUBY
+
+      html_template 'notifier/foo', <<-RUBY
+        <p>Hello, World!</p>
+      RUBY
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      app('development')
+
+      get "/rails/mailers/notifier/foo"
+      assert_equal 200, last_response.status
+      assert_match %r[<iframe seamless name="messageBody"], last_response.body
+
+      get "/rails/mailers/notifier/foo?part=text/plain"
+      assert_equal 200, last_response.status
+      assert_match %r[Hello, World!], last_response.body
+
+      get "/rails/mailers/notifier/foo?part=text/html"
+      assert_equal 200, last_response.status
+      assert_match %r[<p>Hello, World!</p>], last_response.body
+    end
+
+    test "multipart mailer preview with inline attachment" do
+      image_file "pixel.png", "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEWzIioca/JlAAAACklEQVQI12NgAAAAAgAB4iG8MwAAAABJRU5ErkJgggo="
+
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            attachments['pixel.png'] = File.read("#{app_path}/public/images/pixel.png", mode: 'rb')
+            mail to: "to@example.org"
+          end
+        end
+      RUBY
+
+      text_template 'notifier/foo', <<-RUBY
+        Hello, World!
+      RUBY
+
+      html_template 'notifier/foo', <<-RUBY
+        <p>Hello, World!</p>
+        <%= image_tag attachments['pixel.png'].url %>
+      RUBY
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      app('development')
+
+      get "/rails/mailers/notifier/foo"
+      assert_equal 200, last_response.status
+      assert_match %r[<iframe seamless name="messageBody"], last_response.body
+
+      get "/rails/mailers/notifier/foo?part=text/plain"
+      assert_equal 200, last_response.status
+      assert_match %r[Hello, World!], last_response.body
+
+      get "/rails/mailers/notifier/foo?part=text/html"
+      assert_equal 200, last_response.status
+      assert_match %r[<p>Hello, World!</p>], last_response.body
+      assert_match %r[src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEWzIioca/JlAAAACklEQVQI12NgAAAAAgAB4iG8MwAAAABJRU5ErkJgggo="], last_response.body
+    end
+
+    test "multipart mailer preview with attached email" do
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            message = ::Mail.new do
+              from    'foo@example.com'
+              to      'bar@example.com'
+              subject 'Important Message'
+
+              text_part do
+                body 'Goodbye, World!'
+              end
+
+              html_part do
+                body '<p>Goodbye, World!</p>'
+              end
+            end
+
+            attachments['message.eml'] = message.to_s
+            mail to: "to@example.org"
+          end
+        end
+      RUBY
+
+      text_template 'notifier/foo', <<-RUBY
+        Hello, World!
+      RUBY
+
+      html_template 'notifier/foo', <<-RUBY
+        <p>Hello, World!</p>
+      RUBY
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      app('development')
+
+      get "/rails/mailers/notifier/foo"
+      assert_equal 200, last_response.status
+      assert_match %r[<iframe seamless name="messageBody"], last_response.body
+
+      get "/rails/mailers/notifier/foo?part=text/plain"
+      assert_equal 200, last_response.status
+      assert_match %r[Hello, World!], last_response.body
+
+      get "/rails/mailers/notifier/foo?part=text/html"
+      assert_equal 200, last_response.status
+      assert_match %r[<p>Hello, World!</p>], last_response.body
+    end
+
     private
       def build_app
         super
@@ -449,5 +693,9 @@ module ApplicationTests
       def text_template(name, contents)
         app_file("app/views/#{name}.text.erb", contents)
       end
+
+      def image_file(name, contents)
+        app_file("public/images/#{name}", Base64.strict_decode64(contents), 'wb')
+      end
   end
 end
diff --git a/railties/test/application/middleware/exceptions_test.rb b/railties/test/application/middleware/exceptions_test.rb
index a7472b37f1..7b4babb13b 100644
--- a/railties/test/application/middleware/exceptions_test.rb
+++ b/railties/test/application/middleware/exceptions_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'isolation/abstract_unit'
 require 'rack/test'
 
@@ -49,7 +48,7 @@ module ApplicationTests
     test "uses custom exceptions app" do
       add_to_config <<-RUBY
         config.exceptions_app = lambda do |env|
-          [404, { "Content-Type" => "text/plain" }, ["YOU FAILED BRO"]]
+          [404, { "Content-Type" => "text/plain" }, ["YOU FAILED"]]
         end
       RUBY
 
@@ -57,7 +56,7 @@ module ApplicationTests
 
       get "/foo"
       assert_equal 404, last_response.status
-      assert_equal "YOU FAILED BRO", last_response.body
+      assert_equal "YOU FAILED", last_response.body
     end
 
     test "url generation error when action_dispatch.show_exceptions is set raises an exception" do
@@ -68,7 +67,7 @@ module ApplicationTests
           end
         end
       RUBY
-      
+
       app.config.action_dispatch.show_exceptions = true
 
       get '/foo'
diff --git a/railties/test/application/middleware/session_test.rb b/railties/test/application/middleware/session_test.rb
index eb7885e5b1..25eadfc387 100644
--- a/railties/test/application/middleware/session_test.rb
+++ b/railties/test/application/middleware/session_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'isolation/abstract_unit'
 require 'rack/test'
 
@@ -36,7 +35,7 @@ module ApplicationTests
             flash[:notice] = "notice"
           end
 
-          render nothing: true
+          head :ok
         end
       end
 
@@ -61,7 +60,7 @@ module ApplicationTests
 
           def write_session
             session[:foo] = 1
-            render nothing: true
+            head :ok
           end
 
           def read_session
@@ -102,7 +101,7 @@ module ApplicationTests
 
           def write_cookie
             cookies[:foo] = '1'
-            render nothing: true
+            head :ok
           end
 
           def read_cookie
@@ -140,7 +139,7 @@ module ApplicationTests
         class FooController < ActionController::Base
           def write_session
             session[:foo] = 1
-            render nothing: true
+            head :ok
           end
 
           def read_session
@@ -185,7 +184,7 @@ module ApplicationTests
         class FooController < ActionController::Base
           def write_session
             session[:foo] = 1
-            render nothing: true
+            head :ok
           end
 
           def read_session
@@ -235,12 +234,12 @@ module ApplicationTests
           def write_raw_session
             # {"session_id"=>"1965d95720fffc123941bdfb7d2e6870", "foo"=>1}
             cookies[:_myapp_session] = "BAh7B0kiD3Nlc3Npb25faWQGOgZFRkkiJTE5NjVkOTU3MjBmZmZjMTIzOTQxYmRmYjdkMmU2ODcwBjsAVEkiCGZvbwY7AEZpBg==--315fb9931921a87ae7421aec96382f0294119749"
-            render nothing: true
+            head :ok
           end
 
           def write_session
             session[:foo] = session[:foo] + 1
-            render nothing: true
+            head :ok
           end
 
           def read_session
@@ -294,12 +293,12 @@ module ApplicationTests
           def write_raw_session
             # {"session_id"=>"1965d95720fffc123941bdfb7d2e6870", "foo"=>1}
             cookies[:_myapp_session] = "BAh7B0kiD3Nlc3Npb25faWQGOgZFRkkiJTE5NjVkOTU3MjBmZmZjMTIzOTQxYmRmYjdkMmU2ODcwBjsAVEkiCGZvbwY7AEZpBg==--315fb9931921a87ae7421aec96382f0294119749"
-            render nothing: true
+            head :ok
           end
 
           def write_session
             session[:foo] = session[:foo] + 1
-            render nothing: true
+            head :ok
           end
 
           def read_session
diff --git a/railties/test/application/middleware/static_test.rb b/railties/test/application/middleware/static_test.rb
index 0a793f8f60..5366537dc2 100644
--- a/railties/test/application/middleware/static_test.rb
+++ b/railties/test/application/middleware/static_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'isolation/abstract_unit'
 require 'rack/test'
 
@@ -27,5 +26,43 @@ module ApplicationTests
 
       assert_not last_response.headers.has_key?('Cache-Control'), "Cache-Control should not be set"
     end
+
+    test "headers for static files are configurable" do
+      app_file "public/about.html", 'static'
+      add_to_config <<-CONFIG
+        config.public_file_server.headers = {
+          "Access-Control-Allow-Origin" => "http://rubyonrails.org",
+          "Cache-Control"               => "public, max-age=60"
+        }
+      CONFIG
+
+      require "#{app_path}/config/environment"
+
+      get '/about.html'
+
+      assert_equal 'http://rubyonrails.org', last_response.headers["Access-Control-Allow-Origin"]
+      assert_equal 'public, max-age=60',     last_response.headers["Cache-Control"]
+    end
+
+    test "static_index defaults to 'index'" do
+      app_file "public/index.html", "/index.html"
+      
+      require "#{app_path}/config/environment"
+
+      get '/'
+      
+      assert_equal "/index.html\n", last_response.body
+    end
+
+    test "static_index configurable" do
+      app_file "public/other-index.html", "/other-index.html"
+      add_to_config "config.static_index = 'other-index'"
+      
+      require "#{app_path}/config/environment"
+
+      get '/'
+
+      assert_equal "/other-index.html\n", last_response.body
+    end
   end
 end
diff --git a/railties/test/application/middleware_test.rb b/railties/test/application/middleware_test.rb
index c64fe082f3..138c63266e 100644
--- a/railties/test/application/middleware_test.rb
+++ b/railties/test/application/middleware_test.rb
@@ -26,7 +26,7 @@ module ApplicationTests
       assert_equal [
         "Rack::Sendfile",
         "ActionDispatch::Static",
-        "Rack::Lock",
+        "ActionDispatch::LoadInterlock",
         "ActiveSupport::Cache::Strategy::LocalCache",
         "Rack::Runtime",
         "Rack::MethodOverride",
@@ -43,7 +43,32 @@ module ApplicationTests
         "ActionDispatch::Cookies",
         "ActionDispatch::Session::CookieStore",
         "ActionDispatch::Flash",
-        "ActionDispatch::ParamsParser",
+        "Rack::Head",
+        "Rack::ConditionalGet",
+        "Rack::ETag"
+      ], middleware
+    end
+
+    test "api middleware stack" do
+      add_to_config "config.api_only = true"
+
+      boot!
+
+      assert_equal [
+        "Rack::Sendfile",
+        "ActionDispatch::Static",
+        "ActionDispatch::LoadInterlock",
+        "ActiveSupport::Cache::Strategy::LocalCache",
+        "Rack::Runtime",
+        "ActionDispatch::RequestId",
+        "Rails::Rack::Logger", # must come after Rack::MethodOverride to properly log overridden methods
+        "ActionDispatch::ShowExceptions",
+        "ActionDispatch::DebugExceptions",
+        "ActionDispatch::RemoteIp",
+        "ActionDispatch::Reloader",
+        "ActionDispatch::Callbacks",
+        "ActiveRecord::ConnectionAdapters::ConnectionManagement",
+        "ActiveRecord::QueryCache",
         "Rack::Head",
         "Rack::ConditionalGet",
         "Rack::ETag"
@@ -94,23 +119,40 @@ module ApplicationTests
       assert !middleware.include?("ActiveRecord::Migration::CheckPending")
     end
 
-    test "includes lock if cache_classes is set but eager_load is not" do
+    test "includes interlock if cache_classes is set but eager_load is not" do
       add_to_config "config.cache_classes = true"
       boot!
-      assert middleware.include?("Rack::Lock")
+      assert_not_includes middleware, "Rack::Lock"
+      assert_includes middleware, "ActionDispatch::LoadInterlock"
+    end
+
+    test "includes interlock if cache_classes is off" do
+      add_to_config "config.cache_classes = false"
+      boot!
+      assert_not_includes middleware, "Rack::Lock"
+      assert_includes middleware, "ActionDispatch::LoadInterlock"
     end
 
     test "does not include lock if cache_classes is set and so is eager_load" do
       add_to_config "config.cache_classes = true"
       add_to_config "config.eager_load = true"
       boot!
-      assert !middleware.include?("Rack::Lock")
+      assert_not_includes middleware, "Rack::Lock"
+      assert_not_includes middleware, "ActionDispatch::LoadInterlock"
     end
 
-    test "does not include lock if allow_concurrency is set" do
-      add_to_config "config.allow_concurrency = true"
+    test "does not include lock if allow_concurrency is set to :unsafe" do
+      add_to_config "config.allow_concurrency = :unsafe"
       boot!
-      assert !middleware.include?("Rack::Lock")
+      assert_not_includes middleware, "Rack::Lock"
+      assert_not_includes middleware, "ActionDispatch::LoadInterlock"
+    end
+
+    test "includes lock if allow_concurrency is disabled" do
+      add_to_config "config.allow_concurrency = false"
+      boot!
+      assert_includes middleware, "Rack::Lock"
+      assert_not_includes middleware, "ActionDispatch::LoadInterlock"
     end
 
     test "removes static asset server if serve_static_files is disabled" do
@@ -125,6 +167,22 @@ module ApplicationTests
       assert !middleware.include?("ActionDispatch::Static")
     end
 
+    test "can delete a middleware from the stack even if insert_before is added after delete" do
+      add_to_config "config.middleware.delete Rack::Runtime"
+      add_to_config "config.middleware.insert_before(Rack::Runtime, Rack::Config)"
+      boot!
+      assert middleware.include?("Rack::Config")
+      assert_not middleware.include?("Rack::Runtime")
+    end
+
+    test "can delete a middleware from the stack even if insert_after is added after delete" do
+      add_to_config "config.middleware.delete Rack::Runtime"
+      add_to_config "config.middleware.insert_after(Rack::Runtime, Rack::Config)"
+      boot!
+      assert middleware.include?("Rack::Config")
+      assert_not middleware.include?("Rack::Runtime")
+    end
+
     test "includes exceptions middlewares even if action_dispatch.show_exceptions is disabled" do
       add_to_config "config.action_dispatch.show_exceptions = false"
       boot!
diff --git a/railties/test/application/multiple_applications_test.rb b/railties/test/application/multiple_applications_test.rb
index cddc79cc85..f2770a9cb4 100644
--- a/railties/test/application/multiple_applications_test.rb
+++ b/railties/test/application/multiple_applications_test.rb
@@ -118,7 +118,7 @@ module ApplicationTests
       assert_equal 0, run_count, "Without loading the initializers, the count should be 0"
 
       # Set config.eager_load to false so that an eager_load warning doesn't pop up
-      AppTemplate::Application.new { config.eager_load = false }.initialize!
+      AppTemplate::Application.create { config.eager_load = false }.initialize!
 
       assert_equal 3, run_count, "There should have been three initializers that incremented the count"
     end
diff --git a/railties/test/application/per_request_digest_cache_test.rb b/railties/test/application/per_request_digest_cache_test.rb
new file mode 100644
index 0000000000..3198e12662
--- /dev/null
+++ b/railties/test/application/per_request_digest_cache_test.rb
@@ -0,0 +1,63 @@
+require 'isolation/abstract_unit'
+require 'rack/test'
+require 'minitest/mock'
+
+require 'action_view'
+require 'active_support/testing/method_call_assertions'
+
+class PerRequestDigestCacheTest < ActiveSupport::TestCase
+  include ActiveSupport::Testing::Isolation
+  include ActiveSupport::Testing::MethodCallAssertions
+  include Rack::Test::Methods
+
+  setup do
+    build_app
+    add_to_config 'config.consider_all_requests_local = true'
+
+    app_file 'app/models/customer.rb', <<-RUBY
+      class Customer < Struct.new(:name, :id)
+        extend ActiveModel::Naming
+        include ActiveModel::Conversion
+      end
+    RUBY
+
+    app_file 'config/routes.rb', <<-RUBY
+      Rails.application.routes.draw do
+        resources :customers, only: :index
+      end
+    RUBY
+
+    app_file 'app/controllers/customers_controller.rb', <<-RUBY
+      class CustomersController < ApplicationController
+        def index
+          render [ Customer.new('david', 1), Customer.new('dingus', 2) ]
+        end
+      end
+    RUBY
+
+    app_file 'app/views/customers/_customer.html.erb', <<-RUBY
+      <% cache customer do %>
+        <%= customer.name %>
+      <% end %>
+    RUBY
+
+    require "#{app_path}/config/environment"
+  end
+
+  teardown :teardown_app
+
+  test "digests are reused when rendering the same template twice" do
+    get '/customers'
+    assert_equal 200, last_response.status
+
+    assert_equal [ '8ba099b7749542fe765ff34a6824d548' ], ActionView::Digestor.cache.values
+    assert_equal %w(david dingus), last_response.body.split.map(&:strip)
+  end
+
+  test "template digests are cleared before a request" do
+    assert_called(ActionView::Digestor.cache, :clear) do
+      get '/customers'
+      assert_equal 200, last_response.status
+    end
+  end
+end
diff --git a/railties/test/application/rake/dbs_test.rb b/railties/test/application/rake/dbs_test.rb
index c414732f92..f94d08673a 100644
--- a/railties/test/application/rake/dbs_test.rb
+++ b/railties/test/application/rake/dbs_test.rb
@@ -28,11 +28,11 @@ module ApplicationTests
 
       def db_create_and_drop(expected_database)
         Dir.chdir(app_path) do
-          output = `bundle exec rake db:create`
+          output = `bin/rake db:create`
           assert_empty output
           assert File.exist?(expected_database)
           assert_equal expected_database, ActiveRecord::Base.connection_config[:database]
-          output = `bundle exec rake db:drop`
+          output = `bin/rake db:drop`
           assert_empty output
           assert !File.exist?(expected_database)
         end
@@ -49,11 +49,63 @@ module ApplicationTests
         db_create_and_drop database_url_db_name
       end
 
+      def with_database_existing
+        Dir.chdir(app_path) do
+          set_database_url
+          `bin/rake db:create`
+          yield
+          `bin/rake db:drop`
+        end
+      end
+
+      test 'db:create failure because database exists' do
+        with_database_existing do
+          output = `bin/rake db:create 2>&1`
+          assert_match /already exists/, output
+          assert_equal 0, $?.exitstatus
+        end
+      end
+
+      def with_bad_permissions
+        Dir.chdir(app_path) do
+          set_database_url
+          FileUtils.chmod("-w", "db")
+          yield
+          FileUtils.chmod("+w", "db")
+        end
+      end
+
+      test 'db:create failure because bad permissions' do
+        with_bad_permissions do
+          output = `bin/rake db:create 2>&1`
+          assert_match /Couldn't create database/, output
+          assert_equal 1, $?.exitstatus
+        end
+      end
+
+      test 'db:drop failure because database does not exist' do
+        Dir.chdir(app_path) do
+          output = `bin/rake db:drop 2>&1`
+          assert_match /does not exist/, output
+          assert_equal 0, $?.exitstatus
+        end
+      end
+
+      test 'db:drop failure because bad permissions' do
+        with_database_existing do
+          with_bad_permissions do
+            output = `bin/rake db:drop 2>&1`
+            assert_match /Couldn't drop/, output
+            assert_equal 1, $?.exitstatus
+          end
+        end
+      end
+
       def db_migrate_and_status(expected_database)
         Dir.chdir(app_path) do
-          `rails generate model book title:string;
-           bundle exec rake db:migrate`
-          output = `bundle exec rake db:migrate:status`
+          `bin/rails generate model book title:string;
+           bin/rake db:migrate`
+          output = `bin/rake db:migrate:status`
           assert_match(%r{database:\s+\S*#{Regexp.escape(expected_database)}}, output)
           assert_match(/up\s+\d{14}\s+Create books/, output)
         end
@@ -72,8 +124,8 @@ module ApplicationTests
 
       def db_schema_dump
         Dir.chdir(app_path) do
-          `rails generate model book title:string;
-           rake db:migrate db:schema:dump`
+          `bin/rails generate model book title:string;
+           bin/rake db:migrate db:schema:dump`
           schema_dump = File.read("db/schema.rb")
           assert_match(/create_table \"books\"/, schema_dump)
         end
@@ -90,8 +142,8 @@ module ApplicationTests
 
       def db_fixtures_load(expected_database)
         Dir.chdir(app_path) do
-          `rails generate model book title:string;
-           bundle exec rake db:migrate db:fixtures:load`
+          `bin/rails generate model book title:string;
+           bin/rake db:migrate db:fixtures:load`
           assert_match expected_database, ActiveRecord::Base.connection_config[:database]
           require "#{app_path}/app/models/book"
           assert_equal 2, Book.count
@@ -112,8 +164,8 @@ module ApplicationTests
       test 'db:fixtures:load with namespaced fixture' do
         require "#{app_path}/config/environment"
         Dir.chdir(app_path) do
-          `rails generate model admin::book title:string;
-           bundle exec rake db:migrate db:fixtures:load`
+          `bin/rails generate model admin::book title:string;
+           bin/rake db:migrate db:fixtures:load`
           require "#{app_path}/app/models/admin/book"
           assert_equal 2, Admin::Book.count
         end
@@ -121,11 +173,11 @@ module ApplicationTests
 
       def db_structure_dump_and_load(expected_database)
         Dir.chdir(app_path) do
-          `rails generate model book title:string;
-           bundle exec rake db:migrate db:structure:dump`
+          `bin/rails generate model book title:string;
+           bin/rake db:migrate db:structure:dump`
           structure_dump = File.read("db/structure.sql")
           assert_match(/CREATE TABLE \"books\"/, structure_dump)
-          `bundle exec rake environment db:drop db:structure:load`
+          `bin/rake environment db:drop db:structure:load`
           assert_match expected_database, ActiveRecord::Base.connection_config[:database]
           require "#{app_path}/app/models/book"
           #if structure is not loaded correctly, exception would be raised
@@ -147,9 +199,9 @@ module ApplicationTests
       test 'db:structure:dump does not dump schema information when no migrations are used' do
         Dir.chdir(app_path) do
           # create table without migrations
-          `bundle exec rails runner 'ActiveRecord::Base.connection.create_table(:posts) {|t| t.string :title }'`
+          `bin/rails runner 'ActiveRecord::Base.connection.create_table(:posts) {|t| t.string :title }'`
 
-          stderr_output = capture(:stderr) { `bundle exec rake db:structure:dump` }
+          stderr_output = capture(:stderr) { `bin/rake db:structure:dump` }
           assert_empty stderr_output
           structure_dump = File.read("db/structure.sql")
           assert_match(/CREATE TABLE \"posts\"/, structure_dump)
@@ -181,10 +233,38 @@ module ApplicationTests
         end
       end
 
+      test "db:schema:load with inflections" do
+        Dir.chdir(app_path) do
+          app_file 'config/initializers/inflection.rb', <<-RUBY
+            ActiveSupport::Inflector.inflections do |inflect|
+              inflect.irregular 'goose', 'geese'
+            end
+          RUBY
+          app_file 'config/initializers/primary_key_table_name.rb', <<-RUBY
+            ActiveRecord::Base.primary_key_prefix_type = :table_name
+          RUBY
+          app_file 'db/schema.rb', <<-RUBY
+            ActiveRecord::Schema.define(version: 20140423102712) do
+              create_table("goose".pluralize) do |t|
+                t.string :name
+              end
+            end
+          RUBY
+
+          `bin/rake db:schema:load`
+
+          tables = `bin/rails runner 'p ActiveRecord::Base.connection.tables'`.strip
+          assert_match(/"geese"/, tables)
+
+          columns = `bin/rails runner 'p ActiveRecord::Base.connection.columns("geese").map(&:name)'`.strip
+          assert_equal columns, '["gooseid", "name"]'
+        end
+      end
+
       def db_test_load_structure
         Dir.chdir(app_path) do
-          `rails generate model book title:string;
-           bundle exec rake db:migrate db:structure:dump db:test:load_structure`
+          `bin/rails generate model book title:string;
+           bin/rake db:migrate db:structure:dump db:test:load_structure`
           ActiveRecord::Base.configurations = Rails.application.config.database_configuration
           ActiveRecord::Base.establish_connection :test
           require "#{app_path}/app/models/book"
@@ -220,7 +300,7 @@ module ApplicationTests
           RUBY
 
           Dir.chdir(app_path) do
-            database_path = `bundle exec rake db:setup`
+            database_path = `bin/rake db:setup`
             assert_equal "development.sqlite3", File.basename(database_path.strip)
           end
         ensure
diff --git a/railties/test/application/rake/dev_test.rb b/railties/test/application/rake/dev_test.rb
new file mode 100644
index 0000000000..28d8b22a37
--- /dev/null
+++ b/railties/test/application/rake/dev_test.rb
@@ -0,0 +1,35 @@
+require 'isolation/abstract_unit'
+
+module ApplicationTests
+  module RakeTests
+    class RakeDevTest < ActiveSupport::TestCase
+      include ActiveSupport::Testing::Isolation
+
+      def setup
+        build_app
+        boot_rails
+      end
+
+      def teardown
+        teardown_app
+      end
+
+      test 'dev:cache creates file and outputs message' do
+        Dir.chdir(app_path) do
+          output = `rake dev:cache`
+          assert File.exist?('tmp/caching-dev.txt')
+          assert_match(/Development mode is now being cached/, output)
+        end
+      end
+
+      test 'dev:cache deletes file and outputs message' do
+        Dir.chdir(app_path) do
+          output = `rake dev:cache`        
+          output = `rake dev:cache`
+          assert_not File.exist?('tmp/caching-dev.txt')
+          assert_match(/Development mode is no longer being cached/, output)
+        end
+      end
+    end
+  end
+end
diff --git a/railties/test/application/rake/framework_test.rb b/railties/test/application/rake/framework_test.rb
new file mode 100644
index 0000000000..ec57af79f6
--- /dev/null
+++ b/railties/test/application/rake/framework_test.rb
@@ -0,0 +1,48 @@
+require "isolation/abstract_unit"
+require "active_support/core_ext/string/strip"
+
+module ApplicationTests
+  module RakeTests
+    class FrameworkTest < ActiveSupport::TestCase
+      include ActiveSupport::Testing::Isolation
+
+      def setup
+        build_app
+        boot_rails
+        FileUtils.rm_rf("#{app_path}/config/environments")
+      end
+
+      def teardown
+        teardown_app
+      end
+
+      def load_tasks
+        require 'rake'
+        require 'rdoc/task'
+        require 'rake/testtask'
+
+        Rails.application.load_tasks
+      end
+
+      test 'requiring the rake task should not define method .app_generator on Object' do
+        require "#{app_path}/config/environment"
+
+        load_tasks
+
+        assert_raise NameError do
+          Object.method(:app_generator)
+        end
+      end
+
+      test 'requiring the rake task should not define method .invoke_from_app_generator on Object' do
+        require "#{app_path}/config/environment"
+
+        load_tasks
+
+        assert_raise NameError do
+          Object.method(:invoke_from_app_generator)
+        end
+      end
+    end
+  end
+end
diff --git a/railties/test/application/rake/migrations_test.rb b/railties/test/application/rake/migrations_test.rb
index a3819b93b2..2d8bd7c571 100644
--- a/railties/test/application/rake/migrations_test.rb
+++ b/railties/test/application/rake/migrations_test.rb
@@ -15,21 +15,21 @@ module ApplicationTests
 
       test 'running migrations with given scope' do
         Dir.chdir(app_path) do
-          `rails generate model user username:string password:string`
+          `bin/rails generate model user username:string password:string`
 
           app_file "db/migrate/01_a_migration.bukkits.rb", <<-MIGRATION
             class AMigration < ActiveRecord::Migration
             end
           MIGRATION
 
-          output = `rake db:migrate SCOPE=bukkits`
+          output = `bin/rake db:migrate SCOPE=bukkits`
           assert_no_match(/create_table\(:users\)/, output)
           assert_no_match(/CreateUsers/, output)
           assert_no_match(/add_column\(:users, :email, :string\)/, output)
 
           assert_match(/AMigration: migrated/, output)
 
-          output = `rake db:migrate SCOPE=bukkits VERSION=0`
+          output = `bin/rake db:migrate SCOPE=bukkits VERSION=0`
           assert_no_match(/drop_table\(:users\)/, output)
           assert_no_match(/CreateUsers/, output)
           assert_no_match(/remove_column\(:users, :email\)/, output)
@@ -40,16 +40,16 @@ module ApplicationTests
 
       test 'model and migration generator with change syntax' do
         Dir.chdir(app_path) do
-          `rails generate model user username:string password:string;
-           rails generate migration add_email_to_users email:string`
+          `bin/rails generate model user username:string password:string;
+           bin/rails generate migration add_email_to_users email:string`
 
-           output = `rake db:migrate`
+           output = `bin/rake db:migrate`
            assert_match(/create_table\(:users\)/, output)
            assert_match(/CreateUsers: migrated/, output)
            assert_match(/add_column\(:users, :email, :string\)/, output)
            assert_match(/AddEmailToUsers: migrated/, output)
 
-           output = `rake db:rollback STEP=2`
+           output = `bin/rake db:rollback STEP=2`
            assert_match(/drop_table\(:users\)/, output)
            assert_match(/CreateUsers: reverted/, output)
            assert_match(/remove_column\(:users, :email, :string\)/, output)
@@ -58,23 +58,23 @@ module ApplicationTests
       end
 
       test 'migration status when schema migrations table is not present' do
-        output = Dir.chdir(app_path){ `rake db:migrate:status 2>&1` }
+        output = Dir.chdir(app_path){ `bin/rake db:migrate:status 2>&1` }
         assert_equal "Schema migrations table does not exist yet.\n", output
       end
 
       test 'test migration status' do
         Dir.chdir(app_path) do
-          `rails generate model user username:string password:string;
-           rails generate migration add_email_to_users email:string;
-           rake db:migrate`
+          `bin/rails generate model user username:string password:string;
+           bin/rails generate migration add_email_to_users email:string;
+           bin/rake db:migrate`
 
-          output = `rake db:migrate:status`
+          output = `bin/rake db:migrate:status`
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+Add email to users/, output)
 
-          `rake db:rollback STEP=1`
-          output = `rake db:migrate:status`
+          `bin/rake db:rollback STEP=1`
+          output = `bin/rake db:migrate:status`
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/down\s+\d{14}\s+Add email to users/, output)
@@ -85,17 +85,17 @@ module ApplicationTests
         add_to_config('config.active_record.timestamped_migrations = false')
 
         Dir.chdir(app_path) do
-          `rails generate model user username:string password:string;
-           rails generate migration add_email_to_users email:string;
-           rake db:migrate`
+          `bin/rails generate model user username:string password:string;
+           bin/rails generate migration add_email_to_users email:string;
+           bin/rake db:migrate`
 
-          output = `rake db:migrate:status`
+          output = `bin/rake db:migrate:status`
 
           assert_match(/up\s+\d{3,}\s+Create users/, output)
           assert_match(/up\s+\d{3,}\s+Add email to users/, output)
 
-          `rake db:rollback STEP=1`
-          output = `rake db:migrate:status`
+          `bin/rake db:rollback STEP=1`
+          output = `bin/rake db:migrate:status`
 
           assert_match(/up\s+\d{3,}\s+Create users/, output)
           assert_match(/down\s+\d{3,}\s+Add email to users/, output)
@@ -104,23 +104,23 @@ module ApplicationTests
 
       test 'test migration status after rollback and redo' do
         Dir.chdir(app_path) do
-          `rails generate model user username:string password:string;
-           rails generate migration add_email_to_users email:string;
-           rake db:migrate`
+          `bin/rails generate model user username:string password:string;
+           bin/rails generate migration add_email_to_users email:string;
+           bin/rake db:migrate`
 
-           output = `rake db:migrate:status`
+           output = `bin/rake db:migrate:status`
 
            assert_match(/up\s+\d{14}\s+Create users/, output)
            assert_match(/up\s+\d{14}\s+Add email to users/, output)
 
-           `rake db:rollback STEP=2`
-           output = `rake db:migrate:status`
+           `bin/rake db:rollback STEP=2`
+           output = `bin/rake db:migrate:status`
 
            assert_match(/down\s+\d{14}\s+Create users/, output)
            assert_match(/down\s+\d{14}\s+Add email to users/, output)
 
-           `rake db:migrate:redo`
-           output = `rake db:migrate:status`
+           `bin/rake db:migrate:redo`
+           output = `bin/rake db:migrate:status`
 
            assert_match(/up\s+\d{14}\s+Create users/, output)
            assert_match(/up\s+\d{14}\s+Add email to users/, output)
@@ -131,23 +131,23 @@ module ApplicationTests
         add_to_config('config.active_record.timestamped_migrations = false')
 
         Dir.chdir(app_path) do
-          `rails generate model user username:string password:string;
-           rails generate migration add_email_to_users email:string;
-           rake db:migrate`
+          `bin/rails generate model user username:string password:string;
+           bin/rails generate migration add_email_to_users email:string;
+           bin/rake db:migrate`
 
-           output = `rake db:migrate:status`
+           output = `bin/rake db:migrate:status`
 
            assert_match(/up\s+\d{3,}\s+Create users/, output)
            assert_match(/up\s+\d{3,}\s+Add email to users/, output)
 
-           `rake db:rollback STEP=2`
-           output = `rake db:migrate:status`
+           `bin/rake db:rollback STEP=2`
+           output = `bin/rake db:migrate:status`
 
            assert_match(/down\s+\d{3,}\s+Create users/, output)
            assert_match(/down\s+\d{3,}\s+Add email to users/, output)
 
-           `rake db:migrate:redo`
-           output = `rake db:migrate:status`
+           `bin/rake db:migrate:redo`
+           output = `bin/rake db:migrate:status`
 
            assert_match(/up\s+\d{3,}\s+Create users/, output)
            assert_match(/up\s+\d{3,}\s+Add email to users/, output)
@@ -158,27 +158,29 @@ module ApplicationTests
         add_to_config('config.active_record.dump_schema_after_migration = false')
 
         Dir.chdir(app_path) do
-          `rails generate model book title:string;
-           bundle exec rake db:migrate`
+          `bin/rails generate model book title:string`
+          output = `bin/rails generate model author name:string`
+          version = output =~ %r{[^/]+db/migrate/(\d+)_create_authors\.rb} && $1
 
-          assert !File.exist?("db/schema.rb")
+          `bin/rake db:migrate db:rollback db:forward db:migrate:up db:migrate:down VERSION=#{version}`
+          assert !File.exist?("db/schema.rb"), "should not dump schema when configured not to"
         end
 
         add_to_config('config.active_record.dump_schema_after_migration = true')
 
         Dir.chdir(app_path) do
-          `rails generate model author name:string;
-           bundle exec rake db:migrate`
+          `bin/rails generate model reviews book_id:integer`
+          `bin/rake db:migrate`
 
           structure_dump = File.read("db/schema.rb")
-          assert_match(/create_table "authors"/, structure_dump)
+          assert_match(/create_table "reviews"/, structure_dump)
         end
       end
 
       test 'default schema generation after migration' do
         Dir.chdir(app_path) do
-          `rails generate model book title:string;
-           bundle exec rake db:migrate`
+          `bin/rails generate model book title:string;
+           bin/rake db:migrate`
 
           structure_dump = File.read("db/schema.rb")
           assert_match(/create_table "books"/, structure_dump)
@@ -187,12 +189,12 @@ module ApplicationTests
 
       test 'test migration status migrated file is deleted' do
         Dir.chdir(app_path) do
-          `rails generate model user username:string password:string;
-           rails generate migration add_email_to_users email:string;
-           rake db:migrate
+          `bin/rails generate model user username:string password:string;
+           bin/rails generate migration add_email_to_users email:string;
+           bin/rake db:migrate
            rm db/migrate/*email*.rb`
 
-          output = `rake db:migrate:status`
+          output = `bin/rake db:migrate:status`
           File.write('test.txt', output)
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
diff --git a/railties/test/application/rake/notes_test.rb b/railties/test/application/rake/notes_test.rb
index 95087bf29f..c87515f00f 100644
--- a/railties/test/application/rake/notes_test.rb
+++ b/railties/test/application/rake/notes_test.rb
@@ -74,7 +74,7 @@ module ApplicationTests
 
         app_file "some_other_dir/blah.rb", "# TODO: note in some_other directory"
 
-        run_rake_notes "SOURCE_ANNOTATION_DIRECTORIES='some_other_dir' bundle exec rake notes" do |output, lines|
+        run_rake_notes "SOURCE_ANNOTATION_DIRECTORIES='some_other_dir' bin/rake notes" do |output, lines|
           assert_match(/note in app directory/, output)
           assert_match(/note in config directory/, output)
           assert_match(/note in db directory/, output)
@@ -102,7 +102,7 @@ module ApplicationTests
           end
         EOS
 
-        run_rake_notes "bundle exec rake notes_custom" do |output, lines|
+        run_rake_notes "bin/rake notes_custom" do |output, lines|
           assert_match(/\[FIXME\] note in lib directory/, output)
           assert_match(/\[TODO\] note in test directory/, output)
           assert_no_match(/OPTIMIZE/, output)
@@ -114,6 +114,7 @@ module ApplicationTests
       end
 
       test 'register a new extension' do
+        add_to_config "config.assets.precompile = []"
         add_to_config %q{ config.annotations.register_extensions("scss", "sass") { |annotation| /\/\/\s*(#{annotation}):?\s*(.*)$/ } }
         app_file "app/assets/stylesheets/application.css.scss", "// TODO: note in scss"
         app_file "app/assets/stylesheets/application.css.sass", "// TODO: note in sass"
@@ -127,7 +128,7 @@ module ApplicationTests
 
       private
 
-      def run_rake_notes(command = 'bundle exec rake notes')
+      def run_rake_notes(command = 'bin/rake notes')
         boot_rails
         load_tasks
 
diff --git a/railties/test/application/rake/restart_test.rb b/railties/test/application/rake/restart_test.rb
new file mode 100644
index 0000000000..4cae199e6b
--- /dev/null
+++ b/railties/test/application/rake/restart_test.rb
@@ -0,0 +1,39 @@
+require "isolation/abstract_unit"
+
+module ApplicationTests
+  module RakeTests
+    class RakeRestartTest < ActiveSupport::TestCase
+      include ActiveSupport::Testing::Isolation
+
+      def setup
+        build_app
+        boot_rails
+      end
+
+      def teardown
+        teardown_app
+      end
+
+      test 'rake restart touches tmp/restart.txt' do
+        Dir.chdir(app_path) do
+          `rake restart`
+          assert File.exist?("tmp/restart.txt")
+
+          prev_mtime = File.mtime("tmp/restart.txt")
+          sleep(1)
+          `rake restart`
+          curr_mtime = File.mtime("tmp/restart.txt")
+          assert_not_equal prev_mtime, curr_mtime
+        end
+      end
+
+      test 'rake restart should work even if tmp folder does not exist' do
+        Dir.chdir(app_path) do
+          FileUtils.remove_dir('tmp')
+          `rake restart`
+          assert File.exist?('tmp/restart.txt')
+        end
+      end
+    end
+  end
+end
diff --git a/railties/test/application/rake_test.rb b/railties/test/application/rake_test.rb
index e8c8de9f73..0da0928b48 100644
--- a/railties/test/application/rake_test.rb
+++ b/railties/test/application/rake_test.rb
@@ -1,4 +1,3 @@
-# coding:utf-8
 require "isolation/abstract_unit"
 require "active_support/core_ext/string/strip"
 
@@ -36,7 +35,7 @@ module ApplicationTests
         Rails.application.initialize!
       RUBY
 
-      assert_match("SuperMiddleware", Dir.chdir(app_path){ `rake middleware` })
+      assert_match("SuperMiddleware", Dir.chdir(app_path){ `bin/rake middleware` })
     end
 
     def test_initializers_are_executed_in_rake_tasks
@@ -51,7 +50,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path){ `rake do_nothing` }
+      output = Dir.chdir(app_path){ `bin/rake do_nothing` }
       assert_match "Doing something...", output
     end
 
@@ -72,7 +71,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `rake do_nothing` }
+      output = Dir.chdir(app_path) { `bin/rake do_nothing` }
       assert_match 'Hello world', output
     end
 
@@ -93,14 +92,14 @@ module ApplicationTests
       RUBY
 
       Dir.chdir(app_path) do
-        assert system('rake do_nothing RAILS_ENV=production'),
+        assert system('bin/rake do_nothing RAILS_ENV=production'),
                'should not be pre-required for rake even eager_load=true'
       end
     end
 
     def test_code_statistics_sanity
-      assert_match "Code LOC: 5     Test LOC: 0     Code to Test Ratio: 1:0.0",
-        Dir.chdir(app_path){ `rake stats` }
+      assert_match "Code LOC: 7     Test LOC: 0     Code to Test Ratio: 1:0.0",
+        Dir.chdir(app_path){ `bin/rake stats` }
     end
 
     def test_rake_routes_calls_the_route_inspector
@@ -110,7 +109,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path){ `rake routes` }
+      output = Dir.chdir(app_path){ `bin/rake routes` }
       assert_equal "Prefix Verb URI Pattern     Controller#Action\n  cart GET  /cart(.:format) cart#show\n", output
     end
 
@@ -123,7 +122,7 @@ module ApplicationTests
       RUBY
 
       ENV['CONTROLLER'] = 'cart'
-      output = Dir.chdir(app_path){ `rake routes` }
+      output = Dir.chdir(app_path){ `bin/rake routes` }
       assert_equal "Prefix Verb URI Pattern     Controller#Action\n  cart GET  /cart(.:format) cart#show\n", output
     end
 
@@ -133,7 +132,7 @@ module ApplicationTests
         end
       RUBY
 
-      assert_equal <<-MESSAGE.strip_heredoc, Dir.chdir(app_path){ `rake routes` }
+      assert_equal <<-MESSAGE.strip_heredoc, Dir.chdir(app_path){ `bin/rake routes` }
         You don't have any routes defined!
 
         Please add some routes in config/routes.rb.
@@ -151,21 +150,21 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path){ `rake log_something RAILS_ENV=production && cat log/production.log` }
+      output = Dir.chdir(app_path){ `bin/rake log_something RAILS_ENV=production && cat log/production.log` }
       assert_match "Sample log message", output
     end
 
     def test_loading_specific_fixtures
       Dir.chdir(app_path) do
-        `rails generate model user username:string password:string;
-         rails generate model product name:string;
-         rake db:migrate`
+        `bin/rails generate model user username:string password:string;
+         bin/rails generate model product name:string;
+         bin/rake db:migrate`
       end
 
       require "#{rails_root}/config/environment"
 
       # loading a specific fixture
-      errormsg = Dir.chdir(app_path) { `rake db:fixtures:load FIXTURES=products` }
+      errormsg = Dir.chdir(app_path) { `bin/rake db:fixtures:load FIXTURES=products` }
       assert $?.success?, errormsg
 
       assert_equal 2, ::AppTemplate::Application::Product.count
@@ -174,42 +173,64 @@ module ApplicationTests
 
     def test_loading_only_yml_fixtures
       Dir.chdir(app_path) do
-        `rake db:migrate`
+        `bin/rake db:migrate`
       end
 
       app_file "test/fixtures/products.csv", ""
 
       require "#{rails_root}/config/environment"
-      errormsg = Dir.chdir(app_path) { `rake db:fixtures:load` }
+      errormsg = Dir.chdir(app_path) { `bin/rake db:fixtures:load` }
       assert $?.success?, errormsg
     end
 
     def test_scaffold_tests_pass_by_default
       output = Dir.chdir(app_path) do
-        `rails generate scaffold user username:string password:string;
-         bundle exec rake db:migrate test`
+        `bin/rails generate scaffold user username:string password:string;
+         bin/rake db:migrate test`
       end
 
-      assert_match(/7 runs, 13 assertions, 0 failures, 0 errors/, output)
+      assert_match(/7 runs, 12 assertions, 0 failures, 0 errors/, output)
       assert_no_match(/Errors running/, output)
     end
 
-    def test_scaffold_with_references_columns_tests_pass_by_default
+    def test_api_scaffold_tests_pass_by_default
+      add_to_config <<-RUBY
+        config.api_only = true
+      RUBY
+
+      app_file "app/controllers/application_controller.rb", <<-RUBY
+        class ApplicationController < ActionController::API
+        end
+      RUBY
+
       output = Dir.chdir(app_path) do
-        `rails generate scaffold LineItems product:references cart:belongs_to;
-         bundle exec rake db:migrate test`
+        `bin/rails generate scaffold user username:string password:string;
+         bin/rake db:migrate test`
       end
 
-      assert_match(/7 runs, 13 assertions, 0 failures, 0 errors/, output)
+      assert_match(/5 runs, 7 assertions, 0 failures, 0 errors/, output)
+      assert_no_match(/Errors running/, output)
+    end
+
+    def test_scaffold_with_references_columns_tests_pass_when_belongs_to_is_optional
+      app_file "config/initializers/active_record_belongs_to_required_by_default.rb",
+        "Rails.application.config.active_record.belongs_to_required_by_default = false"
+
+      output = Dir.chdir(app_path) do
+        `bin/rails generate scaffold LineItems product:references cart:belongs_to;
+         bin/rake db:migrate test`
+      end
+
+      assert_match(/7 runs, 12 assertions, 0 failures, 0 errors/, output)
       assert_no_match(/Errors running/, output)
     end
 
     def test_db_test_clone_when_using_sql_format
       add_to_config "config.active_record.schema_format = :sql"
       output = Dir.chdir(app_path) do
-        `rails generate scaffold user username:string;
-         bundle exec rake db:migrate;
-         bundle exec rake db:test:clone 2>&1 --trace`
+        `bin/rails generate scaffold user username:string;
+         bin/rake db:migrate;
+         bin/rake db:test:clone 2>&1 --trace`
       end
       assert_match(/Execute db:test:clone_structure/, output)
     end
@@ -217,9 +238,9 @@ module ApplicationTests
     def test_db_test_prepare_when_using_sql_format
       add_to_config "config.active_record.schema_format = :sql"
       output = Dir.chdir(app_path) do
-        `rails generate scaffold user username:string;
-         bundle exec rake db:migrate;
-         bundle exec rake db:test:prepare 2>&1 --trace`
+        `bin/rails generate scaffold user username:string;
+         bin/rake db:migrate;
+         bin/rake db:test:prepare 2>&1 --trace`
       end
       assert_match(/Execute db:test:load_structure/, output)
     end
@@ -227,7 +248,7 @@ module ApplicationTests
     def test_rake_dump_structure_should_respect_db_structure_env_variable
       Dir.chdir(app_path) do
         # ensure we have a schema_migrations table to dump
-        `bundle exec rake db:migrate db:structure:dump DB_STRUCTURE=db/my_structure.sql`
+        `bin/rake db:migrate db:structure:dump SCHEMA=db/my_structure.sql`
       end
       assert File.exist?(File.join(app_path, 'db', 'my_structure.sql'))
     end
@@ -236,8 +257,8 @@ module ApplicationTests
       add_to_config "config.active_record.schema_format = :sql"
 
       output = Dir.chdir(app_path) do
-        `rails g model post title:string;
-         bundle exec rake db:migrate:redo 2>&1 --trace;`
+        `bin/rails g model post title:string;
+         bin/rake db:migrate:redo 2>&1 --trace;`
       end
 
       # expect only Invoke db:structure:dump (first_time)
@@ -246,23 +267,23 @@ module ApplicationTests
 
     def test_rake_dump_schema_cache
       Dir.chdir(app_path) do
-        `rails generate model post title:string;
-         rails generate model product name:string;
-         bundle exec rake db:migrate db:schema:cache:dump`
+        `bin/rails generate model post title:string;
+         bin/rails generate model product name:string;
+         bin/rake db:migrate db:schema:cache:dump`
       end
       assert File.exist?(File.join(app_path, 'db', 'schema_cache.dump'))
     end
 
     def test_rake_clear_schema_cache
       Dir.chdir(app_path) do
-        `bundle exec rake db:schema:cache:dump db:schema:cache:clear`
+        `bin/rake db:schema:cache:dump db:schema:cache:clear`
       end
       assert !File.exist?(File.join(app_path, 'db', 'schema_cache.dump'))
     end
 
     def test_copy_templates
       Dir.chdir(app_path) do
-        `bundle exec rake rails:templates:copy`
+        `bin/rake rails:templates:copy`
         %w(controller mailer scaffold).each do |dir|
           assert File.exist?(File.join(app_path, 'lib', 'templates', 'erb', dir))
         end
@@ -277,10 +298,17 @@ module ApplicationTests
       app_file "template.rb", ""
 
       output = Dir.chdir(app_path) do
-        `bundle exec rake rails:template LOCATION=template.rb`
+        `bin/rake rails:template LOCATION=template.rb`
       end
 
       assert_match(/Hello, World!/, output)
     end
+
+    def test_tmp_clear_should_work_if_folder_missing
+      FileUtils.remove_dir("#{app_path}/tmp")
+      errormsg = Dir.chdir(app_path) { `bin/rake tmp:clear` }
+      assert_predicate $?, :success?
+      assert_empty errormsg
+    end
   end
 end
diff --git a/railties/test/application/routing_test.rb b/railties/test/application/routing_test.rb
index cbada6be97..0777714d35 100644
--- a/railties/test/application/routing_test.rb
+++ b/railties/test/application/routing_test.rb
@@ -21,6 +21,12 @@ module ApplicationTests
       assert_equal 200, last_response.status
     end
 
+    test "rails/info in development" do
+      app("development")
+      get "/rails/info"
+      assert_equal 302, last_response.status
+    end
+
     test "rails/info/routes in development" do
       app("development")
       get "/rails/info/routes"
@@ -63,6 +69,12 @@ module ApplicationTests
       assert_equal 404, last_response.status
     end
 
+    test "rails/info in production" do
+      app("production")
+      get "/rails/info"
+      assert_equal 404, last_response.status
+    end
+
     test "rails/info/routes in production" do
       app("production")
       get "/rails/info/routes"
diff --git a/railties/test/application/runner_test.rb b/railties/test/application/runner_test.rb
index 6595c40f8b..0c180339b4 100644
--- a/railties/test/application/runner_test.rb
+++ b/railties/test/application/runner_test.rb
@@ -25,15 +25,15 @@ module ApplicationTests
     end
 
     def test_should_include_runner_in_shebang_line_in_help_without_option
-      assert_match "/rails runner", Dir.chdir(app_path) { `bundle exec rails runner` }
+      assert_match "/rails runner", Dir.chdir(app_path) { `bin/rails runner` }
     end
 
     def test_should_include_runner_in_shebang_line_in_help
-      assert_match "/rails runner", Dir.chdir(app_path) { `bundle exec rails runner --help` }
+      assert_match "/rails runner", Dir.chdir(app_path) { `bin/rails runner --help` }
     end
 
     def test_should_run_ruby_statement
-      assert_match "42", Dir.chdir(app_path) { `bundle exec rails runner "puts User.count"` }
+      assert_match "42", Dir.chdir(app_path) { `bin/rails runner "puts User.count"` }
     end
 
     def test_should_run_file
@@ -41,7 +41,7 @@ module ApplicationTests
       puts User.count
       SCRIPT
 
-      assert_match "42", Dir.chdir(app_path) { `bundle exec rails runner "bin/count_users.rb"` }
+      assert_match "42", Dir.chdir(app_path) { `bin/rails runner "bin/count_users.rb"` }
     end
 
     def test_should_set_dollar_0_to_file
@@ -49,7 +49,7 @@ module ApplicationTests
       puts $0
       SCRIPT
 
-      assert_match "bin/dollar0.rb", Dir.chdir(app_path) { `bundle exec rails runner "bin/dollar0.rb"` }
+      assert_match "bin/dollar0.rb", Dir.chdir(app_path) { `bin/rails runner "bin/dollar0.rb"` }
     end
 
     def test_should_set_dollar_program_name_to_file
@@ -57,7 +57,7 @@ module ApplicationTests
       puts $PROGRAM_NAME
       SCRIPT
 
-      assert_match "bin/program_name.rb", Dir.chdir(app_path) { `bundle exec rails runner "bin/program_name.rb"` }
+      assert_match "bin/program_name.rb", Dir.chdir(app_path) { `bin/rails runner "bin/program_name.rb"` }
     end
 
     def test_with_hook
@@ -67,22 +67,22 @@ module ApplicationTests
         end
       RUBY
 
-      assert_match "true", Dir.chdir(app_path) { `bundle exec rails runner "puts Rails.application.config.ran"` }
+      assert_match "true", Dir.chdir(app_path) { `bin/rails runner "puts Rails.application.config.ran"` }
     end
 
     def test_default_environment
-      assert_match "development", Dir.chdir(app_path) { `bundle exec rails runner "puts Rails.env"` }
+      assert_match "development", Dir.chdir(app_path) { `bin/rails runner "puts Rails.env"` }
     end
 
     def test_environment_with_rails_env
       with_rails_env "production" do
-        assert_match "production", Dir.chdir(app_path) { `bundle exec rails runner "puts Rails.env"` }
+        assert_match "production", Dir.chdir(app_path) { `bin/rails runner "puts Rails.env"` }
       end
     end
 
     def test_environment_with_rack_env
       with_rack_env "production" do
-        assert_match "production", Dir.chdir(app_path) { `bundle exec rails runner "puts Rails.env"` }
+        assert_match "production", Dir.chdir(app_path) { `bin/rails runner "puts Rails.env"` }
       end
     end
   end
diff --git a/railties/test/application/test_runner_test.rb b/railties/test/application/test_runner_test.rb
index 032b11a95f..0aa6ce2252 100644
--- a/railties/test/application/test_runner_test.rb
+++ b/railties/test/application/test_runner_test.rb
@@ -1,13 +1,13 @@
 require 'isolation/abstract_unit'
 require 'active_support/core_ext/string/strip'
+require 'env_helpers'
 
 module ApplicationTests
   class TestRunnerTest < ActiveSupport::TestCase
-    include ActiveSupport::Testing::Isolation
+    include ActiveSupport::Testing::Isolation, EnvHelpers
 
     def setup
       build_app
-      ENV['RAILS_ENV'] = nil
       create_schema
     end
 
@@ -15,20 +15,6 @@ module ApplicationTests
       teardown_app
     end
 
-    def test_run_in_test_environment
-      app_file 'test/unit/env_test.rb', <<-RUBY
-        require 'test_helper'
-
-        class EnvTest < ActiveSupport::TestCase
-          def test_env
-            puts "Current Environment: \#{Rails.env}"
-          end
-        end
-      RUBY
-
-      assert_match "Current Environment: test", run_test_command('test/unit/env_test.rb')
-    end
-
     def test_run_single_file
       create_test_file :models, 'foo'
       create_test_file :models, 'bar'
@@ -47,16 +33,15 @@ module ApplicationTests
         def; end
       RUBY
 
-      error_stream = Tempfile.new('error')
-      redirect_stderr(error_stream) { run_test_command('test/models/error_test.rb') }
-      assert_match "syntax error", error_stream.read
+      error = capture(:stderr) { run_test_command('test/models/error_test.rb') }
+      assert_match "syntax error", error
     end
 
     def test_run_models
       create_test_file :models, 'foo'
       create_test_file :models, 'bar'
       create_test_file :controllers, 'foobar_controller'
-      run_test_models_command.tap do |output|
+      run_test_command("test/models").tap do |output|
         assert_match "FooTest", output
         assert_match "BarTest", output
         assert_match "2 runs, 2 assertions, 0 failures", output
@@ -67,7 +52,7 @@ module ApplicationTests
       create_test_file :helpers, 'foo_helper'
       create_test_file :helpers, 'bar_helper'
       create_test_file :controllers, 'foobar_controller'
-      run_test_helpers_command.tap do |output|
+      run_test_command("test/helpers").tap do |output|
         assert_match "FooHelperTest", output
         assert_match "BarHelperTest", output
         assert_match "2 runs, 2 assertions, 0 failures", output
@@ -75,6 +60,7 @@ module ApplicationTests
     end
 
     def test_run_units
+      skip "we no longer have the concept of unit tests. Just different directories..."
       create_test_file :models, 'foo'
       create_test_file :helpers, 'bar_helper'
       create_test_file :unit, 'baz_unit'
@@ -91,7 +77,7 @@ module ApplicationTests
       create_test_file :controllers, 'foo_controller'
       create_test_file :controllers, 'bar_controller'
       create_test_file :models, 'foo'
-      run_test_controllers_command.tap do |output|
+      run_test_command("test/controllers").tap do |output|
         assert_match "FooControllerTest", output
         assert_match "BarControllerTest", output
         assert_match "2 runs, 2 assertions, 0 failures", output
@@ -102,7 +88,7 @@ module ApplicationTests
       create_test_file :mailers, 'foo_mailer'
       create_test_file :mailers, 'bar_mailer'
       create_test_file :models, 'foo'
-      run_test_mailers_command.tap do |output|
+      run_test_command("test/mailers").tap do |output|
         assert_match "FooMailerTest", output
         assert_match "BarMailerTest", output
         assert_match "2 runs, 2 assertions, 0 failures", output
@@ -113,7 +99,7 @@ module ApplicationTests
       create_test_file :jobs, 'foo_job'
       create_test_file :jobs, 'bar_job'
       create_test_file :models, 'foo'
-      run_test_jobs_command.tap do |output|
+      run_test_command("test/jobs").tap do |output|
         assert_match "FooJobTest", output
         assert_match "BarJobTest", output
         assert_match "2 runs, 2 assertions, 0 failures", output
@@ -121,6 +107,7 @@ module ApplicationTests
     end
 
     def test_run_functionals
+      skip "we no longer have the concept of functional tests. Just different directories..."
       create_test_file :mailers, 'foo_mailer'
       create_test_file :controllers, 'bar_controller'
       create_test_file :functional, 'baz_functional'
@@ -136,7 +123,7 @@ module ApplicationTests
     def test_run_integration
       create_test_file :integration, 'foo_integration'
       create_test_file :models, 'foo'
-      run_test_integration_command.tap do |output|
+      run_test_command("test/integration").tap do |output|
         assert_match "FooIntegration", output
         assert_match "1 runs, 1 assertions, 0 failures", output
       end
@@ -166,7 +153,7 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('test/unit/chu_2_koi_test.rb test_rikka').tap do |output|
+      run_test_command('-n test_rikka test/unit/chu_2_koi_test.rb').tap do |output|
         assert_match "Rikka", output
         assert_no_match "Sanae", output
       end
@@ -187,7 +174,7 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('test/unit/chu_2_koi_test.rb /rikka/').tap do |output|
+      run_test_command('-n /rikka/ test/unit/chu_2_koi_test.rb').tap do |output|
         assert_match "Rikka", output
         assert_no_match "Sanae", output
       end
@@ -195,18 +182,18 @@ module ApplicationTests
 
     def test_load_fixtures_when_running_test_suites
       create_model_with_fixture
-      suites = [:models, :helpers, [:units, :unit], :controllers, :mailers,
-        [:functionals, :functional], :integration]
+      suites = [:models, :helpers, :controllers, :mailers, :integration]
 
       suites.each do |suite, directory|
         directory ||= suite
         create_fixture_test directory
-        assert_match "3 users", run_task(["test:#{suite}"])
+        assert_match "3 users", run_test_command("test/#{suite}")
         Dir.chdir(app_path) { FileUtils.rm_f "test/#{directory}" }
       end
     end
 
     def test_run_with_model
+      skip "These feel a bit odd. Not sure we should keep supporting them."
       create_model_with_fixture
       create_fixture_test 'models', 'user'
       assert_match "3 users", run_task(["test models/user"])
@@ -214,6 +201,7 @@ module ApplicationTests
     end
 
     def test_run_different_environment_using_env_var
+      skip "no longer possible. Running tests in a different environment should be explicit"
       app_file 'test/unit/env_test.rb', <<-RUBY
         require 'test_helper'
 
@@ -228,19 +216,17 @@ module ApplicationTests
       assert_match "development", run_test_command('test/unit/env_test.rb')
     end
 
-    def test_run_different_environment_using_e_tag
-      env = "development"
-      app_file 'test/unit/env_test.rb', <<-RUBY
-        require 'test_helper'
+    def test_run_in_test_environment_by_default
+      create_env_test
 
-        class EnvTest < ActiveSupport::TestCase
-          def test_env
-            puts Rails.env
-          end
-        end
-      RUBY
+      assert_match "Current Environment: test", run_test_command('test/unit/env_test.rb')
+    end
 
-      assert_match env, run_test_command("test/unit/env_test.rb RAILS_ENV=#{env}")
+    def test_run_different_environment
+      create_env_test
+
+      assert_match "Current Environment: development",
+        run_test_command("-e development test/unit/env_test.rb")
     end
 
     def test_generated_scaffold_works_with_rails_test
@@ -248,18 +234,141 @@ module ApplicationTests
       assert_match "0 failures, 0 errors, 0 skips", run_test_command('')
     end
 
-    private
-      def run_task(tasks)
-        Dir.chdir(app_path) { `bundle exec rake #{tasks.join ' '}` }
+    def test_run_multiple_folders
+      create_test_file :models, 'account'
+      create_test_file :controllers, 'accounts_controller'
+
+      run_test_command('test/models test/controllers').tap do |output|
+        assert_match 'AccountTest', output
+        assert_match 'AccountsControllerTest', output
+        assert_match '2 runs, 2 assertions, 0 failures, 0 errors, 0 skips', output
       end
+    end
 
-      def run_test_command(arguments = 'test/unit/test_test.rb')
-        run_task ['test', arguments]
+    def test_run_with_ruby_command
+      app_file 'test/models/post_test.rb', <<-RUBY
+        require 'test_helper'
+
+        class PostTest < ActiveSupport::TestCase
+          test 'declarative syntax works' do
+            puts 'PostTest'
+            assert true
+          end
+        end
+      RUBY
+
+      Dir.chdir(app_path) do
+        `ruby -Itest test/models/post_test.rb`.tap do |output|
+          assert_match 'PostTest', output
+          assert_no_match 'is already defined in', output
+        end
       end
-      %w{ mailers models helpers units controllers functionals integration jobs }.each do |type|
-        define_method("run_test_#{type}_command") do
-          run_task ["test:#{type}"]
+    end
+
+    def test_mix_files_and_line_filters
+      create_test_file :models, 'account'
+      app_file 'test/models/post_test.rb', <<-RUBY
+        require 'test_helper'
+
+        class PostTest < ActiveSupport::TestCase
+          def test_post
+            puts 'PostTest'
+            assert true
+          end
+
+          def test_line_filter_does_not_run_this
+            assert true
+          end
         end
+      RUBY
+
+      run_test_command('test/models/account_test.rb test/models/post_test.rb:4').tap do |output|
+        assert_match 'AccountTest', output
+        assert_match 'PostTest', output
+        assert_match '2 runs, 2 assertions', output
+      end
+    end
+
+    def test_multiple_line_filters
+      create_test_file :models, 'account'
+      create_test_file :models, 'post'
+
+      run_test_command('test/models/account_test.rb:4 test/models/post_test.rb:4').tap do |output|
+        assert_match 'AccountTest', output
+        assert_match 'PostTest', output
+      end
+    end
+
+    def test_line_filter_without_line_runs_all_tests
+      create_test_file :models, 'account'
+
+      run_test_command('test/models/account_test.rb:').tap do |output|
+        assert_match 'AccountTest', output
+      end
+    end
+
+    def test_shows_filtered_backtrace_by_default
+      create_backtrace_test
+
+      assert_match 'Rails::BacktraceCleaner', run_test_command('test/unit/backtrace_test.rb')
+    end
+
+    def test_backtrace_option
+      create_backtrace_test
+
+      assert_match 'Minitest::BacktraceFilter', run_test_command('test/unit/backtrace_test.rb -b')
+      assert_match 'Minitest::BacktraceFilter',
+        run_test_command('test/unit/backtrace_test.rb --backtrace')
+    end
+
+    def test_show_full_backtrace_using_backtrace_environment_variable
+      create_backtrace_test
+
+      switch_env 'BACKTRACE', 'true' do
+        assert_match 'Minitest::BacktraceFilter', run_test_command('test/unit/backtrace_test.rb')
+      end
+    end
+
+    def test_run_app_without_rails_loaded
+      # Simulate a real Rails app boot.
+      app_file 'config/boot.rb', <<-RUBY
+        ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
+
+        require 'bundler/setup' # Set up gems listed in the Gemfile.
+      RUBY
+
+      assert_match '0 runs, 0 assertions', run_test_command('')
+    end
+
+    def test_output_inline_by_default
+      create_test_file :models, 'post', pass: false
+
+      output = run_test_command('test/models/post_test.rb')
+      assert_match %r{Running:\n\nPostTest\nF\n\nwups!\n\nbin/rails test test/models/post_test.rb:4}, output
+    end
+
+    def test_only_inline_failure_output
+      create_test_file :models, 'post', pass: false
+
+      output = run_test_command('test/models/post_test.rb')
+      assert_match %r{Finished in.*\n\n1 runs, 1 assertions}, output
+    end
+
+    def test_fail_fast
+      create_test_file :models, 'post', pass: false
+
+      assert_match(/Interrupt/,
+        capture(:stderr) { run_test_command('test/models/post_test.rb --fail-fast') })
+    end
+
+    def test_raise_error_when_specified_file_does_not_exist
+      error = capture(:stderr) { run_test_command('test/not_exists.rb') }
+      assert_match(%r{cannot load such file.+test/not_exists\.rb}, error)
+    end
+
+    private
+      def run_test_command(arguments = 'test/unit/test_test.rb')
+        Dir.chdir(app_path) { `bin/rails t #{arguments}` }
       end
 
       def create_model_with_fixture
@@ -292,27 +401,42 @@ module ApplicationTests
         RUBY
       end
 
-      def create_schema
-        app_file 'db/schema.rb', ''
+      def create_backtrace_test
+        app_file 'test/unit/backtrace_test.rb', <<-RUBY
+          require 'test_helper'
+
+          class BacktraceTest < ActiveSupport::TestCase
+            def test_backtrace
+              puts Minitest.backtrace_filter
+            end
+          end
+        RUBY
       end
 
-      def redirect_stderr(target_stream)
-        previous_stderr = STDERR.dup
-        $stderr.reopen(target_stream)
-        yield
-        target_stream.rewind
-      ensure
-        $stderr = previous_stderr
+      def create_schema
+        app_file 'db/schema.rb', ''
       end
 
-      def create_test_file(path = :unit, name = 'test')
+      def create_test_file(path = :unit, name = 'test', pass: true)
         app_file "test/#{path}/#{name}_test.rb", <<-RUBY
           require 'test_helper'
 
           class #{name.camelize}Test < ActiveSupport::TestCase
             def test_truth
               puts "#{name.camelize}Test"
-              assert true
+              assert #{pass}, 'wups!'
+            end
+          end
+        RUBY
+      end
+
+      def create_env_test
+        app_file 'test/unit/env_test.rb', <<-RUBY
+          require 'test_helper'
+
+          class EnvTest < ActiveSupport::TestCase
+            def test_env
+              puts "Current Environment: \#{Rails.env}"
             end
           end
         RUBY
@@ -325,7 +449,7 @@ module ApplicationTests
       end
 
       def run_migration
-        Dir.chdir(app_path) { `bundle exec rake db:migrate` }
+        Dir.chdir(app_path) { `bin/rake db:migrate` }
       end
   end
 end
diff --git a/railties/test/application/test_test.rb b/railties/test/application/test_test.rb
index c7132837b1..0e997f4ba7 100644
--- a/railties/test/application/test_test.rb
+++ b/railties/test/application/test_test.rb
@@ -44,7 +44,7 @@ module ApplicationTests
           def test_index
             get '/posts'
             assert_response :success
-            assert_template "index"
+            assert_includes @response.body, 'Posts#index'
           end
         end
       RUBY
@@ -64,7 +64,8 @@ module ApplicationTests
       RUBY
 
       output = run_test_file('unit/failing_test.rb', env: { "BACKTRACE" => "1" })
-      assert_match %r{/app/test/unit/failing_test\.rb}, output
+      assert_match %r{test/unit/failing_test\.rb}, output
+      assert_match %r{test/unit/failing_test\.rb:4}, output
     end
 
     test "ruby schema migrations" do
@@ -300,23 +301,7 @@ Expected: ["id", "name"]
       end
 
       def run_test_file(name, options = {})
-        ruby '-Itest', "#{app_path}/test/#{name}", options.deep_merge(env: {"RAILS_ENV" => "test"})
-      end
-
-      def ruby(*args)
-        options = args.extract_options!
-        env = options.fetch(:env, {})
-        env["RUBYLIB"] = $:.join(':')
-
-        Dir.chdir(app_path) do
-          `#{env_string(env)} #{Gem.ruby} #{args.join(' ')} 2>&1`
-        end
-      end
-
-      def env_string(variables)
-        variables.map do |key, value|
-          "#{key}='#{value}'"
-        end.join " "
+        Dir.chdir(app_path) { `bin/rails test "#{app_path}/test/#{name}" 2>&1` }
       end
   end
 end
diff --git a/railties/test/application/url_generation_test.rb b/railties/test/application/url_generation_test.rb
index ef16ab56ed..894e18cb39 100644
--- a/railties/test/application/url_generation_test.rb
+++ b/railties/test/application/url_generation_test.rb
@@ -42,5 +42,18 @@ module ApplicationTests
       get "/"
       assert_equal "/", last_response.body
     end
+
+    def test_routes_know_the_relative_root
+      boot_rails
+      require "rails"
+      require "action_controller/railtie"
+      require "action_view/railtie"
+
+      relative_url = '/hello'
+      ENV["RAILS_RELATIVE_URL_ROOT"] = relative_url
+      app = Class.new(Rails::Application)
+      assert_equal relative_url, app.routes.relative_url_root
+      ENV["RAILS_RELATIVE_URL_ROOT"] = nil
+    end
   end
 end
diff --git a/railties/test/code_statistics_test.rb b/railties/test/code_statistics_test.rb
new file mode 100644
index 0000000000..1b1ff80bc1
--- /dev/null
+++ b/railties/test/code_statistics_test.rb
@@ -0,0 +1,20 @@
+require 'abstract_unit'
+require 'rails/code_statistics'
+
+class CodeStatisticsTest < ActiveSupport::TestCase
+  def setup
+    @tmp_path = File.expand_path(File.join(File.dirname(__FILE__), 'fixtures', 'tmp'))
+    @dir_js   = File.expand_path(File.join(File.dirname(__FILE__), 'fixtures', 'tmp', 'lib.js'))
+    FileUtils.mkdir_p(@dir_js)
+  end
+
+  def teardown
+    FileUtils.rm_rf(@tmp_path)
+  end
+
+  test 'ignores directories that happen to have source files extensions' do
+    assert_nothing_raised do
+      @code_statistics = CodeStatistics.new(['tmp dir', @tmp_path])
+    end
+  end
+end
diff --git a/railties/test/commands/dbconsole_test.rb b/railties/test/commands/dbconsole_test.rb
index a3cd1eb0ed..7950ed6aa7 100644
--- a/railties/test/commands/dbconsole_test.rb
+++ b/railties/test/commands/dbconsole_test.rb
@@ -99,19 +99,15 @@ class Rails::DBConsoleTest < ActiveSupport::TestCase
   end
 
   def test_rails_env_is_development_when_argument_is_dev
-    dbconsole = Rails::DBConsole.new
-
-    dbconsole.stub(:available_environments, ['development', 'test']) do
-      options = dbconsole.send(:parse_arguments, ['dev'])
+    Rails::DBConsole.stub(:available_environments, ['development', 'test']) do
+      options = Rails::DBConsole.send(:parse_arguments, ['dev'])
       assert_match('development', options[:environment])
     end
   end
 
   def test_rails_env_is_dev_when_argument_is_dev_and_dev_env_is_present
-    dbconsole = Rails::DBConsole.new
-
-    dbconsole.stub(:available_environments, ['dev']) do
-      options = dbconsole.send(:parse_arguments, ['dev'])
+    Rails::DBConsole.stub(:available_environments, ['dev']) do
+      options = Rails::DBConsole.send(:parse_arguments, ['dev'])
       assert_match('dev', options[:environment])
     end
   end
@@ -158,12 +154,6 @@ class Rails::DBConsoleTest < ActiveSupport::TestCase
     assert_equal 'q1w2e3', ENV['PGPASSWORD']
   end
 
-  def test_sqlite
-    start(adapter: 'sqlite', database: 'db')
-    assert !aborted
-    assert_equal ['sqlite', 'db'], dbconsole.find_cmd_and_exec_args
-  end
-
   def test_sqlite3
     start(adapter: 'sqlite3', database: 'db.sqlite3')
     assert !aborted
diff --git a/railties/test/commands/server_test.rb b/railties/test/commands/server_test.rb
index ba688f1e9e..3be4a74f74 100644
--- a/railties/test/commands/server_test.rb
+++ b/railties/test/commands/server_test.rb
@@ -44,6 +44,29 @@ class Rails::ServerTest < ActiveSupport::TestCase
     end
   end
 
+  def test_environment_with_port
+    switch_env "PORT", "1234" do
+      server = Rails::Server.new
+      assert_equal 1234, server.options[:Port]
+    end
+  end
+
+  def test_caching_without_option
+    args = []
+    options = Rails::Server::Options.new.parse!(args)
+    assert_equal nil, options[:caching]
+  end
+
+  def test_caching_with_option
+    args = ["--dev-caching"]
+    options = Rails::Server::Options.new.parse!(args)
+    assert_equal true, options[:caching]
+
+    args = ["--no-dev-caching"]
+    options = Rails::Server::Options.new.parse!(args)
+    assert_equal false, options[:caching]
+  end
+
   def test_log_stdout
     with_rack_env nil do
       with_rails_env nil do
diff --git a/railties/test/generators/actions_test.rb b/railties/test/generators/actions_test.rb
index c4b6441397..fabba555ef 100644
--- a/railties/test/generators/actions_test.rb
+++ b/railties/test/generators/actions_test.rb
@@ -1,7 +1,6 @@
 require 'generators/generators_test_helper'
 require 'rails/generators/rails/app/app_generator'
 require 'env_helpers'
-require 'mocha/setup' # FIXME: stop using mocha
 
 class ActionsTest < Rails::Generators::TestCase
   include GeneratorsTestHelper
@@ -45,6 +44,14 @@ class ActionsTest < Rails::Generators::TestCase
     assert_file 'Gemfile', /source 'http:\/\/gems\.github\.com'/
   end
 
+  def test_add_source_with_block_adds_source_to_gemfile_with_gem
+    run_generator
+    action :add_source, 'http://gems.github.com' do
+      gem 'rspec-rails'
+    end
+    assert_file 'Gemfile', /source 'http:\/\/gems\.github\.com' do\n  gem 'rspec-rails'\nend/
+  end
+
   def test_gem_should_put_gem_dependency_in_gemfile
     run_generator
     action :gem, 'will-paginate'
@@ -140,13 +147,15 @@ class ActionsTest < Rails::Generators::TestCase
   end
 
   def test_git_with_symbol_should_run_command_using_git_scm
-    generator.expects(:run).once.with('git init')
-    action :git, :init
+    assert_called_with(generator, :run, ['git init']) do
+      action :git, :init
+    end
   end
 
   def test_git_with_hash_should_run_each_command_using_git_scm
-    generator.expects(:run).times(2)
-    action :git, rm: 'README', add: '.'
+    assert_called_with(generator, :run, [ ["git rm README"], ["git add ."] ]) do
+      action :git, rm: 'README', add: '.'
+    end
   end
 
   def test_vendor_should_write_data_to_file_in_vendor
@@ -170,46 +179,53 @@ class ActionsTest < Rails::Generators::TestCase
   end
 
   def test_generate_should_run_script_generate_with_argument_and_options
-    generator.expects(:run_ruby_script).once.with('bin/rails generate model MyModel', verbose: false)
-    action :generate, 'model', 'MyModel'
+    assert_called_with(generator, :run_ruby_script, ['bin/rails generate model MyModel', verbose: false]) do
+      action :generate, 'model', 'MyModel'
+    end
   end
 
   def test_rake_should_run_rake_command_with_default_env
-    generator.expects(:run).once.with("rake log:clear RAILS_ENV=development", verbose: false)
-    with_rails_env nil do
-      action :rake, 'log:clear'
+    assert_called_with(generator, :run, ["rake log:clear RAILS_ENV=development", verbose: false]) do
+      with_rails_env nil do
+        action :rake, 'log:clear'
+      end
     end
   end
 
   def test_rake_with_env_option_should_run_rake_command_in_env
-    generator.expects(:run).once.with('rake log:clear RAILS_ENV=production', verbose: false)
-    action :rake, 'log:clear', env: 'production'
+    assert_called_with(generator, :run, ['rake log:clear RAILS_ENV=production', verbose: false]) do
+      action :rake, 'log:clear', env: 'production'
+    end
   end
 
   def test_rake_with_rails_env_variable_should_run_rake_command_in_env
-    generator.expects(:run).once.with('rake log:clear RAILS_ENV=production', verbose: false)
-    with_rails_env "production" do
-      action :rake, 'log:clear'
+    assert_called_with(generator, :run, ['rake log:clear RAILS_ENV=production', verbose: false]) do
+      with_rails_env "production" do
+        action :rake, 'log:clear'
+      end
     end
   end
 
   def test_env_option_should_win_over_rails_env_variable_when_running_rake
-    generator.expects(:run).once.with('rake log:clear RAILS_ENV=production', verbose: false)
-    with_rails_env "staging" do
-      action :rake, 'log:clear', env: 'production'
+    assert_called_with(generator, :run, ['rake log:clear RAILS_ENV=production', verbose: false]) do
+      with_rails_env "staging" do
+        action :rake, 'log:clear', env: 'production'
+      end
     end
   end
 
   def test_rake_with_sudo_option_should_run_rake_command_with_sudo
-    generator.expects(:run).once.with("sudo rake log:clear RAILS_ENV=development", verbose: false)
-    with_rails_env nil do
-      action :rake, 'log:clear', sudo: true
+    assert_called_with(generator, :run, ["sudo rake log:clear RAILS_ENV=development", verbose: false]) do
+      with_rails_env nil do
+        action :rake, 'log:clear', sudo: true
+      end
     end
   end
 
   def test_capify_should_run_the_capify_command
-    generator.expects(:run).once.with('capify .', verbose: false)
-    action :capify!
+    assert_called_with(generator, :run, ['capify .', verbose: false]) do
+      action :capify!
+    end
   end
 
   def test_route_should_add_data_to_the_routes_block_in_config_routes
@@ -219,17 +235,43 @@ class ActionsTest < Rails::Generators::TestCase
     assert_file 'config/routes.rb', /#{Regexp.escape(route_command)}/
   end
 
+  def test_route_should_add_data_with_an_new_line
+    run_generator
+    action :route, "root 'welcome#index'"
+    route_path = File.expand_path("config/routes.rb", destination_root)
+    content = File.read(route_path)
+
+    # Remove all of the comments and blank lines from the routes file
+    content.gsub!(/^  \#.*\n/, '')
+    content.gsub!(/^\n/, '')
+
+    File.open(route_path, "wb") { |file| file.write(content) }
+    assert_file "config/routes.rb", /\.routes\.draw do\n  root 'welcome#index'\nend\n\z/
+
+    action :route, "resources :product_lines"
+
+    routes = <<-F
+Rails.application.routes.draw do
+  resources :product_lines
+  root 'welcome#index'
+end
+F
+    assert_file "config/routes.rb", routes
+  end
+
   def test_readme
     run_generator
-    Rails::Generators::AppGenerator.expects(:source_root).times(2).returns(destination_root)
-    assert_match "application up and running", action(:readme, "README.rdoc")
+    assert_called(Rails::Generators::AppGenerator, :source_root, times: 2, returns: destination_root) do
+      assert_match "application up and running", action(:readme, "README.md")
+    end
   end
 
   def test_readme_with_quiet
     generator(default_arguments, quiet: true)
     run_generator
-    Rails::Generators::AppGenerator.expects(:source_root).times(2).returns(destination_root)
-    assert_no_match "application up and running", action(:readme, "README.rdoc")
+    assert_called(Rails::Generators::AppGenerator, :source_root, times: 2, returns: destination_root) do
+      assert_no_match "application up and running", action(:readme, "README.md")
+    end
   end
 
   def test_log
diff --git a/railties/test/generators/api_app_generator_test.rb b/railties/test/generators/api_app_generator_test.rb
new file mode 100644
index 0000000000..998da3ef84
--- /dev/null
+++ b/railties/test/generators/api_app_generator_test.rb
@@ -0,0 +1,97 @@
+require 'generators/generators_test_helper'
+require 'rails/generators/rails/app/app_generator'
+
+class ApiAppGeneratorTest < Rails::Generators::TestCase
+  include GeneratorsTestHelper
+  tests Rails::Generators::AppGenerator
+
+  arguments [destination_root, '--api']
+
+  def setup
+    Rails.application = TestApp::Application
+    super
+
+    Kernel::silence_warnings do
+      Thor::Base.shell.send(:attr_accessor, :always_force)
+      @shell = Thor::Base.shell.new
+      @shell.send(:always_force=, true)
+    end
+  end
+
+  def teardown
+    super
+    Rails.application = TestApp::Application.instance
+  end
+
+  def test_skeleton_is_created
+    run_generator
+
+    default_files.each { |path| assert_file path }
+    skipped_files.each { |path| assert_no_file path }
+  end
+
+  def test_api_modified_files
+    run_generator
+
+    assert_file "Gemfile" do |content|
+      assert_no_match(/gem 'coffee-rails'/, content)
+      assert_no_match(/gem 'jquery-rails'/, content)
+      assert_no_match(/gem 'sass-rails'/, content)
+      assert_no_match(/gem 'jbuilder'/, content)
+      assert_no_match(/gem 'web-console'/, content)
+      assert_match(/gem 'active_model_serializers'/, content)
+    end
+
+    assert_file "config/application.rb" do |content|
+      assert_match(/config.api_only = true/, content)
+    end
+
+    assert_file "config/initializers/cors.rb"
+
+    assert_file "config/initializers/wrap_parameters.rb"
+
+    assert_file "app/controllers/application_controller.rb", /ActionController::API/
+  end
+
+  private
+
+  def default_files
+    files = %W(
+      .gitignore
+      Gemfile
+      Rakefile
+      config.ru
+      app/controllers
+      app/mailers
+      app/models
+      config/environments
+      config/initializers
+      config/locales
+      db
+      lib
+      lib/tasks
+      log
+      test/fixtures
+      test/controllers
+      test/integration
+      test/models
+      tmp
+      vendor
+    )
+    files.concat %w(bin/bundle bin/rails bin/rake)
+    files
+  end
+
+  def skipped_files
+    %w(app/assets
+       app/helpers
+       app/views
+       config/initializers/assets.rb
+       config/initializers/cookies_serializer.rb
+       config/initializers/session_store.rb
+       lib/assets
+       vendor/assets
+       test/helpers
+       tmp/cache/assets)
+  end
+end
diff --git a/railties/test/generators/app_generator_test.rb b/railties/test/generators/app_generator_test.rb
index 5d270555ed..e5f10a89d3 100644
--- a/railties/test/generators/app_generator_test.rb
+++ b/railties/test/generators/app_generator_test.rb
@@ -1,11 +1,10 @@
 require 'generators/generators_test_helper'
 require 'rails/generators/rails/app/app_generator'
 require 'generators/shared_generator_tests'
-require 'mocha/setup' # FIXME: stop using mocha
 
 DEFAULT_APP_FILES = %w(
   .gitignore
-  README.rdoc
+  README.md
   Gemfile
   Rakefile
   config.ru
@@ -18,6 +17,7 @@ DEFAULT_APP_FILES = %w(
   app/mailers
   app/models
   app/models/concerns
+  app/jobs
   app/views/layouts
   bin/bundle
   bin/rails
@@ -33,6 +33,7 @@ DEFAULT_APP_FILES = %w(
   log
   test/test_helper.rb
   test/fixtures
+  test/fixtures/files
   test/controllers
   test/models
   test/helpers
@@ -42,6 +43,7 @@ DEFAULT_APP_FILES = %w(
   vendor/assets
   vendor/assets/stylesheets
   vendor/assets/javascripts
+  tmp
   tmp/cache
   tmp/cache/assets
 )
@@ -66,6 +68,11 @@ class AppGeneratorTest < Rails::Generators::TestCase
     assert_file("app/assets/javascripts/application.js")
   end
 
+  def test_application_job_file_present
+    run_generator
+    assert_file("app/jobs/application_job.rb")
+  end
+
   def test_invalid_application_name_raises_an_error
     content = capture(:stderr){ run_generator [File.join(destination_root, "43-things")] }
     assert_equal "Invalid application name 43-things. Please give a name which does not start with numbers.\n", content
@@ -109,35 +116,33 @@ class AppGeneratorTest < Rails::Generators::TestCase
 
     run_generator [app_root]
 
-    Rails.application.config.root = app_moved_root
-    Rails.application.class.stubs(:name).returns("Myapp")
-    Rails.application.stubs(:is_a?).returns(Rails::Application)
+    stub_rails_application(app_moved_root) do
+      Rails.application.stub(:is_a?, -> *args { Rails::Application }) do
+        FileUtils.mv(app_root, app_moved_root)
 
-    FileUtils.mv(app_root, app_moved_root)
+        # make sure we are in correct dir
+        FileUtils.cd(app_moved_root)
 
-    # make sure we are in correct dir
-    FileUtils.cd(app_moved_root)
-
-    generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true },
-                                                               destination_root: app_moved_root, shell: @shell
-    generator.send(:app_const)
-    quietly { generator.send(:update_config_files) }
-    assert_file "myapp_moved/config/environment.rb", /Rails\.application\.initialize!/
-    assert_file "myapp_moved/config/initializers/session_store.rb", /_myapp_session/
+        generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true },
+                                                                   destination_root: app_moved_root, shell: @shell
+        generator.send(:app_const)
+        quietly { generator.send(:update_config_files) }
+        assert_file "myapp_moved/config/environment.rb", /Rails\.application\.initialize!/
+        assert_file "myapp_moved/config/initializers/session_store.rb", /_myapp_session/
+      end
+    end
   end
 
   def test_rails_update_generates_correct_session_key
     app_root = File.join(destination_root, 'myapp')
     run_generator [app_root]
 
-    Rails.application.config.root = app_root
-    Rails.application.class.stubs(:name).returns("Myapp")
-    Rails.application.stubs(:is_a?).returns(Rails::Application)
-
-    generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
-    generator.send(:app_const)
-    quietly { generator.send(:update_config_files) }
-    assert_file "myapp/config/initializers/session_store.rb", /_myapp_session/
+    stub_rails_application(app_root) do
+      generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
+      generator.send(:app_const)
+      quietly { generator.send(:update_config_files) }
+      assert_file "myapp/config/initializers/session_store.rb", /_myapp_session/
+    end
   end
 
   def test_new_application_use_json_serialzier
@@ -150,14 +155,12 @@ class AppGeneratorTest < Rails::Generators::TestCase
     app_root = File.join(destination_root, 'myapp')
     run_generator [app_root]
 
-    Rails.application.config.root = app_root
-    Rails.application.class.stubs(:name).returns("Myapp")
-    Rails.application.stubs(:is_a?).returns(Rails::Application)
-
-    generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
-    generator.send(:app_const)
-    quietly { generator.send(:update_config_files) }
-    assert_file("#{app_root}/config/initializers/cookies_serializer.rb", /Rails\.application\.config\.action_dispatch\.cookies_serializer = :json/)
+    stub_rails_application(app_root) do
+      generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
+      generator.send(:app_const)
+      quietly { generator.send(:update_config_files) }
+      assert_file("#{app_root}/config/initializers/cookies_serializer.rb", /Rails\.application\.config\.action_dispatch\.cookies_serializer = :json/)
+    end
   end
 
   def test_rails_update_does_not_create_callback_terminator_initializer
@@ -166,14 +169,12 @@ class AppGeneratorTest < Rails::Generators::TestCase
 
     FileUtils.rm("#{app_root}/config/initializers/callback_terminator.rb")
 
-    Rails.application.config.root = app_root
-    Rails.application.class.stubs(:name).returns("Myapp")
-    Rails.application.stubs(:is_a?).returns(Rails::Application)
-
-    generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
-    generator.send(:app_const)
-    quietly { generator.send(:update_config_files) }
-    assert_no_file "#{app_root}/config/initializers/callback_terminator.rb"
+    stub_rails_application(app_root) do
+      generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
+      generator.send(:app_const)
+      quietly { generator.send(:update_config_files) }
+      assert_no_file "#{app_root}/config/initializers/callback_terminator.rb"
+    end
   end
 
   def test_rails_update_does_not_remove_callback_terminator_initializer_if_already_present
@@ -182,14 +183,12 @@ class AppGeneratorTest < Rails::Generators::TestCase
 
     FileUtils.touch("#{app_root}/config/initializers/callback_terminator.rb")
 
-    Rails.application.config.root = app_root
-    Rails.application.class.stubs(:name).returns("Myapp")
-    Rails.application.stubs(:is_a?).returns(Rails::Application)
-
-    generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
-    generator.send(:app_const)
-    quietly { generator.send(:update_config_files) }
-    assert_file "#{app_root}/config/initializers/callback_terminator.rb"
+    stub_rails_application(app_root) do
+      generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
+      generator.send(:app_const)
+      quietly { generator.send(:update_config_files) }
+      assert_file "#{app_root}/config/initializers/callback_terminator.rb"
+    end
   end
 
   def test_rails_update_set_the_cookie_serializer_to_marchal_if_it_is_not_already_configured
@@ -198,14 +197,40 @@ class AppGeneratorTest < Rails::Generators::TestCase
 
     FileUtils.rm("#{app_root}/config/initializers/cookies_serializer.rb")
 
-    Rails.application.config.root = app_root
-    Rails.application.class.stubs(:name).returns("Myapp")
-    Rails.application.stubs(:is_a?).returns(Rails::Application)
+    stub_rails_application(app_root) do
+      generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
+      generator.send(:app_const)
+      quietly { generator.send(:update_config_files) }
+      assert_file("#{app_root}/config/initializers/cookies_serializer.rb", /Rails\.application\.config\.action_dispatch\.cookies_serializer = :marshal/)
+    end
+  end
+
+  def test_rails_update_does_not_create_active_record_belongs_to_required_by_default
+    app_root = File.join(destination_root, 'myapp')
+    run_generator [app_root]
+
+    FileUtils.rm("#{app_root}/config/initializers/active_record_belongs_to_required_by_default.rb")
 
-    generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
-    generator.send(:app_const)
-    quietly { generator.send(:update_config_files) }
-    assert_file("#{app_root}/config/initializers/cookies_serializer.rb", /Rails\.application\.config\.action_dispatch\.cookies_serializer = :marshal/)
+    stub_rails_application(app_root) do
+      generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
+      generator.send(:app_const)
+      quietly { generator.send(:update_config_files) }
+      assert_no_file "#{app_root}/config/initializers/active_record_belongs_to_required_by_default.rb"
+    end
+  end
+
+  def test_rails_update_does_not_remove_active_record_belongs_to_required_by_default_if_already_present
+    app_root = File.join(destination_root, 'myapp')
+    run_generator [app_root]
+
+    FileUtils.touch("#{app_root}/config/initializers/active_record_belongs_to_required_by_default.rb")
+
+    stub_rails_application(app_root) do
+      generator = Rails::Generators::AppGenerator.new ["rails"], { with_dispatchers: true }, destination_root: app_root, shell: @shell
+      generator.send(:app_const)
+      quietly { generator.send(:update_config_files) }
+      assert_file "#{app_root}/config/initializers/active_record_belongs_to_required_by_default.rb"
+    end
   end
 
   def test_application_names_are_not_singularized
@@ -308,6 +333,7 @@ class AppGeneratorTest < Rails::Generators::TestCase
   def test_generator_if_skip_active_record_is_given
     run_generator [destination_root, "--skip-active-record"]
     assert_no_file "config/database.yml"
+    assert_no_file "config/initializers/active_record_belongs_to_required_by_default.rb"
     assert_file "config/application.rb", /#\s+require\s+["']active_record\/railtie["']/
     assert_file "test/test_helper.rb" do |helper_content|
       assert_no_match(/fixtures :all/, helper_content)
@@ -409,31 +435,21 @@ class AppGeneratorTest < Rails::Generators::TestCase
     end
   end
 
-  def test_inclusion_of_method_source
-    run_generator
-    assert_file "Gemfile" do |content|
-      assert_gem 'method_source'
-    end
-  end
-
-  def test_inclusion_of_doc
-    run_generator
-    assert_file 'Gemfile', /gem 'sdoc',\s+'~> 0.4.0',\s+group: :doc/
-  end
-
   def test_template_from_dir_pwd
     FileUtils.cd(Rails.root)
     assert_match(/It works from file!/, run_generator([destination_root, "-m", "lib/template.rb"]))
   end
 
   def test_usage_read_from_file
-    File.expects(:read).returns("USAGE FROM FILE")
-    assert_equal "USAGE FROM FILE", Rails::Generators::AppGenerator.desc
+    assert_called(File, :read, returns: "USAGE FROM FILE") do
+      assert_equal "USAGE FROM FILE", Rails::Generators::AppGenerator.desc
+    end
   end
 
   def test_default_usage
-    Rails::Generators::AppGenerator.expects(:usage_path).returns(nil)
-    assert_match(/Create rails files for app generator/, Rails::Generators::AppGenerator.desc)
+    assert_called(Rails::Generators::AppGenerator, :usage_path, returns: nil) do
+      assert_match(/Create rails files for app generator/, Rails::Generators::AppGenerator.desc)
+    end
   end
 
   def test_default_namespace
@@ -445,13 +461,13 @@ class AppGeneratorTest < Rails::Generators::TestCase
     assert_file 'lib/test_file.rb', 'heres test data'
   end
 
-  def test_test_unit_is_removed_from_frameworks_if_skip_test_unit_is_given
-    run_generator [destination_root, "--skip-test-unit"]
+  def test_tests_are_removed_from_frameworks_if_skip_test_is_given
+    run_generator [destination_root, "--skip-test"]
     assert_file "config/application.rb", /#\s+require\s+["']rails\/test_unit\/railtie["']/
   end
 
-  def test_no_active_record_or_test_unit_if_skips_given
-    run_generator [destination_root, "--skip-test-unit", "--skip-active-record"]
+  def test_no_active_record_or_tests_if_skips_given
+    run_generator [destination_root, "--skip-test", "--skip-active-record"]
     assert_file "config/application.rb", /#\s+require\s+["']rails\/test_unit\/railtie["']/
     assert_file "config/application.rb", /#\s+require\s+["']active_record\/railtie["']/
     assert_file "config/application.rb", /\s+require\s+["']active_job\/railtie["']/
@@ -470,7 +486,7 @@ class AppGeneratorTest < Rails::Generators::TestCase
   end
 
   def test_application_name_with_spaces
-    path = File.join(destination_root, "foo bar".shellescape)
+    path = File.join(destination_root, "foo bar")
 
     # This also applies to MySQL apps but not with SQLite
     run_generator [path, "-d", 'postgresql']
@@ -488,7 +504,7 @@ class AppGeneratorTest < Rails::Generators::TestCase
     run_generator [destination_root, "--dev"]
 
     assert_file "Gemfile" do |content|
-      assert_match(/gem 'web-console',\s+github: "rails\/web-console"/, content)
+      assert_match(/gem 'web-console',\s+github: 'rails\/web-console'/, content)
       assert_no_match(/gem 'web-console', '~> 2.0'/, content)
     end
   end
@@ -497,7 +513,7 @@ class AppGeneratorTest < Rails::Generators::TestCase
     run_generator [destination_root, "--edge"]
 
     assert_file "Gemfile" do |content|
-      assert_match(/gem 'web-console',\s+github: "rails\/web-console"/, content)
+      assert_match(/gem 'web-console',\s+github: 'rails\/web-console'/, content)
       assert_no_match(/gem 'web-console', '~> 2.0'/, content)
     end
   end
@@ -509,18 +525,31 @@ class AppGeneratorTest < Rails::Generators::TestCase
 
   def test_spring_binstubs
     jruby_skip "spring doesn't run on JRuby"
-    generator.stubs(:bundle_command).with('install')
-    generator.expects(:bundle_command).with('exec spring binstub --all').once
-    quietly { generator.invoke_all }
+    command_check = -> command do
+      @binstub_called ||= 0
+
+      case command
+      when 'install'
+        # Called when running bundle, we just want to stub it so nothing to do here.
+      when 'exec spring binstub --all'
+        @binstub_called += 1
+        assert_equal 1, @binstub_called, "exec spring binstub --all expected to be called once, but was called #{@install_called} times."
+      end
+    end
+
+    generator.stub :bundle_command, command_check do
+      quietly { generator.invoke_all }
+    end
   end
 
   def test_spring_no_fork
     jruby_skip "spring doesn't run on JRuby"
-    Process.stubs(:respond_to?).with(:fork).returns(false)
-    run_generator
+    assert_called_with(Process, :respond_to?, [:fork], returns: false) do
+      run_generator
 
-    assert_file "Gemfile" do |content|
-      assert_no_match(/spring/, content)
+      assert_file "Gemfile" do |content|
+        assert_no_match(/spring/, content)
+      end
     end
   end
 
@@ -532,6 +561,14 @@ class AppGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_spring_with_dev_option
+    run_generator [destination_root, "--dev"]
+
+    assert_file "Gemfile" do |content|
+      assert_no_match(/spring/, content)
+    end
+  end
+
   def test_generator_if_skip_turbolinks_is_given
     run_generator [destination_root, "--skip-turbolinks"]
 
@@ -570,6 +607,32 @@ class AppGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_create_keeps
+    run_generator
+    folders_with_keep = %w(
+      app/assets/images
+      app/mailers
+      app/models
+      app/controllers/concerns
+      app/models/concerns
+      lib/tasks
+      lib/assets
+      log
+      test/fixtures
+      test/fixtures/files
+      test/controllers
+      test/mailers
+      test/models
+      test/helpers
+      test/integration
+      tmp
+      vendor/assets/stylesheets
+    )
+    folders_with_keep.each do |folder|
+      assert_file("#{folder}/.keep")
+    end
+  end
+
   def test_psych_gem
     run_generator
     gem_regex = /gem 'psych',\s+'~> 2.0',\s+platforms: :rbx/
@@ -588,18 +651,37 @@ class AppGeneratorTest < Rails::Generators::TestCase
     template = %{ after_bundle { run 'echo ran after_bundle' } }
     template.instance_eval "def read; self; end" # Make the string respond to read
 
-    generator([destination_root], template: path).expects(:open).with(path, 'Accept' => 'application/x-thor-template').returns(template)
+    check_open = -> *args do
+      assert_equal [ path, 'Accept' => 'application/x-thor-template' ], args
+      template
+    end
+
+    sequence = ['install', 'exec spring binstub --all', 'echo ran after_bundle']
+    ensure_bundler_first = -> command do
+      @sequence_step ||= 0
 
-    bundler_first = sequence('bundle, binstubs, after_bundle')
-    generator.expects(:bundle_command).with('install').once.in_sequence(bundler_first)
-    generator.expects(:bundle_command).with('exec spring binstub --all').in_sequence(bundler_first)
-    generator.expects(:run).with('echo ran after_bundle').in_sequence(bundler_first)
+      assert_equal sequence[@sequence_step], command, "commands should be called in sequence #{sequence}"
+      @sequence_step += 1
+    end
 
-    quietly { generator.invoke_all }
+    generator([destination_root], template: path).stub(:open, check_open, template) do
+      generator.stub(:bundle_command, ensure_bundler_first) do
+        generator.stub(:run, ensure_bundler_first) do
+          quietly { generator.invoke_all }
+        end
+      end
+    end
   end
 
   protected
 
+  def stub_rails_application(root)
+    Rails.application.config.root = root
+    Rails.application.class.stub(:name, "Myapp") do
+      yield
+    end
+  end
+
   def action(*args, &block)
     capture(:stdout) { generator.send(*args, &block) }
   end
diff --git a/railties/test/generators/controller_generator_test.rb b/railties/test/generators/controller_generator_test.rb
index a7d56dd352..1351151afb 100644
--- a/railties/test/generators/controller_generator_test.rb
+++ b/railties/test/generators/controller_generator_test.rb
@@ -96,6 +96,8 @@ class ControllerGeneratorTest < Rails::Generators::TestCase
 
   def test_namespaced_routes_are_created_in_routes
     run_generator ["admin/dashboard", "index"]
-    assert_file "config/routes.rb", /namespace :admin do\n\s+get 'dashboard\/index'\n/
+    assert_file "config/routes.rb" do |route|
+      assert_match(/^  namespace :admin do\n    get 'dashboard\/index'\n  end$/, route)
+    end
   end
 end
diff --git a/railties/test/generators/generators_test_helper.rb b/railties/test/generators/generators_test_helper.rb
index 7c5183e6c8..b19a5a7144 100644
--- a/railties/test/generators/generators_test_helper.rb
+++ b/railties/test/generators/generators_test_helper.rb
@@ -1,5 +1,7 @@
 require 'abstract_unit'
 require 'active_support/core_ext/module/remove_method'
+require 'active_support/testing/stream'
+require 'active_support/testing/method_call_assertions'
 require 'rails/generators'
 require 'rails/generators/test_case'
 
@@ -23,6 +25,9 @@ require 'action_dispatch'
 require 'action_view'
 
 module GeneratorsTestHelper
+  include ActiveSupport::Testing::Stream
+  include ActiveSupport::Testing::MethodCallAssertions
+
   def self.included(base)
     base.class_eval do
       destination File.join(Rails.root, "tmp")
@@ -42,21 +47,4 @@ module GeneratorsTestHelper
     FileUtils.cp routes, destination
   end
 
-  def quietly
-    silence_stream(STDOUT) do
-      silence_stream(STDERR) do
-        yield
-      end
-    end
-  end
-
-  def silence_stream(stream)
-    old_stream = stream.dup
-    stream.reopen(IO::NULL)
-    stream.sync = true
-    yield
-  ensure
-    stream.reopen(old_stream)
-    old_stream.close
-  end
 end
diff --git a/railties/test/generators/job_generator_test.rb b/railties/test/generators/job_generator_test.rb
index a9e0cea94f..7fd8f2062f 100644
--- a/railties/test/generators/job_generator_test.rb
+++ b/railties/test/generators/job_generator_test.rb
@@ -7,14 +7,14 @@ class JobGeneratorTest < Rails::Generators::TestCase
   def test_job_skeleton_is_created
     run_generator ["refresh_counters"]
     assert_file "app/jobs/refresh_counters_job.rb" do |job|
-      assert_match(/class RefreshCountersJob < ActiveJob::Base/, job)
+      assert_match(/class RefreshCountersJob < ApplicationJob/, job)
     end
   end
 
   def test_job_queue_param
     run_generator ["refresh_counters", "--queue", "important"]
     assert_file "app/jobs/refresh_counters_job.rb" do |job|
-      assert_match(/class RefreshCountersJob < ActiveJob::Base/, job)
+      assert_match(/class RefreshCountersJob < ApplicationJob/, job)
       assert_match(/queue_as :important/, job)
     end
   end
@@ -22,7 +22,7 @@ class JobGeneratorTest < Rails::Generators::TestCase
   def test_job_namespace
     run_generator ["admin/refresh_counters", "--queue", "admin"]
     assert_file "app/jobs/admin/refresh_counters_job.rb" do |job|
-      assert_match(/class Admin::RefreshCountersJob < ActiveJob::Base/, job)
+      assert_match(/class Admin::RefreshCountersJob < ApplicationJob/, job)
       assert_match(/queue_as :admin/, job)
     end
   end
diff --git a/railties/test/generators/mailer_generator_test.rb b/railties/test/generators/mailer_generator_test.rb
index febd2fd12e..f01e8cd2d9 100644
--- a/railties/test/generators/mailer_generator_test.rb
+++ b/railties/test/generators/mailer_generator_test.rb
@@ -47,13 +47,13 @@ class MailerGeneratorTest < Rails::Generators::TestCase
       assert_match(/test "bar"/, test)
     end
     assert_file "test/mailers/previews/notifier_mailer_preview.rb" do |preview|
-      assert_match(/\# Preview all emails at http:\/\/localhost\:3000\/rails\/mailers\/notifier/, preview)
+      assert_match(/\# Preview all emails at http:\/\/localhost\:3000\/rails\/mailers\/notifier_mailer/, preview)
       assert_match(/class NotifierMailerPreview < ActionMailer::Preview/, preview)
-      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/notifier\/foo/, preview)
+      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/notifier_mailer\/foo/, preview)
       assert_instance_method :foo, preview do |foo|
         assert_match(/NotifierMailer.foo/, foo)
       end
-      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/notifier\/bar/, preview)
+      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/notifier_mailer\/bar/, preview)
       assert_instance_method :bar, preview do |bar|
         assert_match(/NotifierMailer.bar/, bar)
       end
@@ -78,13 +78,13 @@ class MailerGeneratorTest < Rails::Generators::TestCase
 
   def test_invokes_default_text_template_engine
     run_generator
-    assert_file "app/views/notifier/foo.text.erb" do |view|
-      assert_match(%r(\sapp/views/notifier/foo\.text\.erb), view)
+    assert_file "app/views/notifier_mailer/foo.text.erb" do |view|
+      assert_match(%r(\sapp/views/notifier_mailer/foo\.text\.erb), view)
       assert_match(/<%= @greeting %>/, view)
     end
 
-    assert_file "app/views/notifier/bar.text.erb" do |view|
-      assert_match(%r(\sapp/views/notifier/bar\.text\.erb), view)
+    assert_file "app/views/notifier_mailer/bar.text.erb" do |view|
+      assert_match(%r(\sapp/views/notifier_mailer/bar\.text\.erb), view)
       assert_match(/<%= @greeting %>/, view)
     end
 
@@ -95,13 +95,13 @@ class MailerGeneratorTest < Rails::Generators::TestCase
 
   def test_invokes_default_html_template_engine
     run_generator
-    assert_file "app/views/notifier/foo.html.erb" do |view|
-      assert_match(%r(\sapp/views/notifier/foo\.html\.erb), view)
+    assert_file "app/views/notifier_mailer/foo.html.erb" do |view|
+      assert_match(%r(\sapp/views/notifier_mailer/foo\.html\.erb), view)
       assert_match(/<%= @greeting %>/, view)
     end
 
-    assert_file "app/views/notifier/bar.html.erb" do |view|
-      assert_match(%r(\sapp/views/notifier/bar\.html\.erb), view)
+    assert_file "app/views/notifier_mailer/bar.html.erb" do |view|
+      assert_match(%r(\sapp/views/notifier_mailer/bar\.html\.erb), view)
       assert_match(/<%= @greeting %>/, view)
     end
 
@@ -112,7 +112,7 @@ class MailerGeneratorTest < Rails::Generators::TestCase
 
   def test_invokes_default_template_engine_even_with_no_action
     run_generator ["notifier"]
-    assert_file "app/views/notifier"
+    assert_file "app/views/notifier_mailer"
     assert_file "app/views/layouts/mailer.text.erb"
     assert_file "app/views/layouts/mailer.html.erb"
   end
@@ -129,12 +129,12 @@ class MailerGeneratorTest < Rails::Generators::TestCase
       assert_match(/en\.farm\.animal_mailer\.moos\.subject/, mailer)
     end
     assert_file "test/mailers/previews/farm/animal_mailer_preview.rb" do |preview|
-      assert_match(/\# Preview all emails at http:\/\/localhost\:3000\/rails\/mailers\/farm\/animal/, preview)
+      assert_match(/\# Preview all emails at http:\/\/localhost\:3000\/rails\/mailers\/farm\/animal_mailer/, preview)
       assert_match(/class Farm::AnimalMailerPreview < ActionMailer::Preview/, preview)
-      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/farm\/animal\/moos/, preview)
+      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/farm\/animal_mailer\/moos/, preview)
     end
-    assert_file "app/views/farm/animal/moos.text.erb"
-    assert_file "app/views/farm/animal/moos.html.erb"
+    assert_file "app/views/farm/animal_mailer/moos.text.erb"
+    assert_file "app/views/farm/animal_mailer/moos.html.erb"
   end
 
   def test_actions_are_turned_into_methods
@@ -173,5 +173,14 @@ class MailerGeneratorTest < Rails::Generators::TestCase
 
     assert_no_file "app/mailers/notifier_mailer_mailer.rb"
     assert_file "app/mailers/notifier_mailer.rb"
+
+    assert_no_file "app/views/notifier_mailer_mailer/"
+    assert_file "app/views/notifier_mailer/"
+
+    assert_no_file "test/mailers/notifier_mailer_mailer_test.rb"
+    assert_file "test/mailers/notifier_mailer_test.rb"
+
+    assert_no_file "test/mailers/previews/notifier_mailer_mailer_preview.rb"
+    assert_file "test/mailers/previews/notifier_mailer_preview.rb"
   end
 end
diff --git a/railties/test/generators/migration_generator_test.rb b/railties/test/generators/migration_generator_test.rb
index 57bc220558..199743a396 100644
--- a/railties/test/generators/migration_generator_test.rb
+++ b/railties/test/generators/migration_generator_test.rb
@@ -221,6 +221,15 @@ class MigrationGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_add_uuid_to_create_table_migration
+    run_generator ["create_books", "--primary_key_type=uuid"]
+    assert_migration "db/migrate/create_books.rb" do |content|
+      assert_method :change, content do |change|
+        assert_match(/create_table :books, id: :uuid/, change)
+      end
+    end
+  end
+
   def test_should_create_empty_migrations_if_name_not_start_with_add_or_remove_or_create
     migration = "delete_books"
     run_generator [migration, "title:string", "content:text"]
diff --git a/railties/test/generators/model_generator_test.rb b/railties/test/generators/model_generator_test.rb
index 17a13fbf1f..64b9a480f3 100644
--- a/railties/test/generators/model_generator_test.rb
+++ b/railties/test/generators/model_generator_test.rb
@@ -319,6 +319,16 @@ class ModelGeneratorTest < Rails::Generators::TestCase
     assert_no_file "test/fixtures/accounts.yml"
   end
 
+  def test_fixture_without_pluralization
+    original_pluralize_table_name = ActiveRecord::Base.pluralize_table_names
+    ActiveRecord::Base.pluralize_table_names = false
+    run_generator
+    assert_generated_fixture("test/fixtures/account.yml",
+                             {"one"=>{"name"=>"MyString", "age"=>1}, "two"=>{"name"=>"MyString", "age"=>1}})
+  ensure
+    ActiveRecord::Base.pluralize_table_names = original_pluralize_table_name
+  end
+
   def test_check_class_collision
     content = capture(:stderr){ run_generator ["object"] }
     assert_match(/The name 'Object' is either already used in your application or reserved/, content)
@@ -364,6 +374,15 @@ class ModelGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_add_uuid_to_create_table_migration
+    run_generator ["account", "--primary_key_type=uuid"]
+    assert_migration "db/migrate/create_accounts.rb" do |content|
+      assert_method :change, content do |change|
+        assert_match(/create_table :accounts, id: :uuid/, change)
+      end
+    end
+  end
+
   def test_required_belongs_to_adds_required_association
     run_generator ["account", "supplier:references{required}"]
 
diff --git a/railties/test/generators/named_base_test.rb b/railties/test/generators/named_base_test.rb
index 4199e00b0d..291f5e06c3 100644
--- a/railties/test/generators/named_base_test.rb
+++ b/railties/test/generators/named_base_test.rb
@@ -1,16 +1,5 @@
 require 'generators/generators_test_helper'
 require 'rails/generators/rails/scaffold_controller/scaffold_controller_generator'
-require 'mocha/setup' # FIXME: stop using mocha
-
-# Mock out what we need from AR::Base.
-module ActiveRecord
-  class Base
-    class << self
-      attr_accessor :pluralize_table_names
-    end
-    self.pluralize_table_names = true
-  end
-end
 
 class NamedBaseTest < Rails::Generators::TestCase
   include GeneratorsTestHelper
@@ -59,11 +48,13 @@ class NamedBaseTest < Rails::Generators::TestCase
   end
 
   def test_named_generator_attributes_without_pluralized
+    original_pluralize_table_names = ActiveRecord::Base.pluralize_table_names
     ActiveRecord::Base.pluralize_table_names = false
+
     g = generator ['admin/foo']
     assert_name g, 'admin_foo', :table_name
   ensure
-    ActiveRecord::Base.pluralize_table_names = true
+    ActiveRecord::Base.pluralize_table_names = original_pluralize_table_names
   end
 
   def test_scaffold_plural_names
@@ -88,10 +79,13 @@ class NamedBaseTest < Rails::Generators::TestCase
 
   def test_application_name
     g = generator ['Admin::Foo']
-    Rails.stubs(:application).returns(Object.new)
-    assert_name g, "object", :application_name
-    Rails.stubs(:application).returns(nil)
-    assert_name g, "application", :application_name
+    Rails.stub(:application, Object.new) do
+      assert_name g, "object", :application_name
+    end
+
+    Rails.stub(:application, nil) do
+      assert_name g, "application", :application_name
+    end
   end
 
   def test_index_helper
@@ -111,11 +105,11 @@ class NamedBaseTest < Rails::Generators::TestCase
 
   def test_hide_namespace
     g = generator ['Hidden']
-    g.class.stubs(:namespace).returns('hidden')
-
-    assert !Rails::Generators.hidden_namespaces.include?('hidden')
-    g.class.hide!
-    assert Rails::Generators.hidden_namespaces.include?('hidden')
+    g.class.stub(:namespace, 'hidden') do
+      assert !Rails::Generators.hidden_namespaces.include?('hidden')
+      g.class.hide!
+      assert Rails::Generators.hidden_namespaces.include?('hidden')
+    end
   end
 
   def test_scaffold_plural_names_with_model_name_option
diff --git a/railties/test/generators/namespaced_generators_test.rb b/railties/test/generators/namespaced_generators_test.rb
index d0ea01dfb0..c4ee6602c5 100644
--- a/railties/test/generators/namespaced_generators_test.rb
+++ b/railties/test/generators/namespaced_generators_test.rb
@@ -173,20 +173,20 @@ class NamespacedMailerGeneratorTest < NamespacedGeneratorTestCase
 
   def test_invokes_default_template_engine
     run_generator
-    assert_file "app/views/test_app/notifier/foo.text.erb" do |view|
-      assert_match(%r(app/views/test_app/notifier/foo\.text\.erb), view)
+    assert_file "app/views/test_app/notifier_mailer/foo.text.erb" do |view|
+      assert_match(%r(app/views/test_app/notifier_mailer/foo\.text\.erb), view)
       assert_match(/<%= @greeting %>/, view)
     end
 
-    assert_file "app/views/test_app/notifier/bar.text.erb" do |view|
-      assert_match(%r(app/views/test_app/notifier/bar\.text\.erb), view)
+    assert_file "app/views/test_app/notifier_mailer/bar.text.erb" do |view|
+      assert_match(%r(app/views/test_app/notifier_mailer/bar\.text\.erb), view)
       assert_match(/<%= @greeting %>/, view)
     end
   end
 
   def test_invokes_default_template_engine_even_with_no_action
     run_generator ["notifier"]
-    assert_file "app/views/test_app/notifier"
+    assert_file "app/views/test_app/notifier_mailer"
   end
 end
 
@@ -281,6 +281,7 @@ class NamespacedScaffoldGeneratorTest < NamespacedGeneratorTestCase
     # Controller
     assert_file "app/controllers/test_app/admin/roles_controller.rb" do |content|
       assert_match(/module TestApp\n  class Admin::RolesController < ApplicationController/, content)
+      assert_match(%r(require_dependency "test_app/application_controller"), content)
     end
 
     assert_file "test/controllers/test_app/admin/roles_controller_test.rb",
diff --git a/railties/test/generators/plugin_generator_test.rb b/railties/test/generators/plugin_generator_test.rb
index 318ea5b2cb..715debf344 100644
--- a/railties/test/generators/plugin_generator_test.rb
+++ b/railties/test/generators/plugin_generator_test.rb
@@ -1,7 +1,6 @@
 require 'generators/generators_test_helper'
 require 'rails/generators/rails/plugin/plugin_generator'
 require 'generators/shared_generator_tests'
-require 'mocha/setup' # FIXME: stop using mocha
 
 DEFAULT_PLUGIN_FILES = %w(
   .gitignore
@@ -28,23 +27,30 @@ class PluginGeneratorTest < Rails::Generators::TestCase
   include SharedGeneratorTests
 
   def test_invalid_plugin_name_raises_an_error
-    content = capture(:stderr){ run_generator [File.join(destination_root, "things-43")] }
-    assert_equal "Invalid plugin name things-43. Please give a name which use only alphabetic or numeric or \"_\" characters.\n", content
+    content = capture(:stderr){ run_generator [File.join(destination_root, "my_plugin-31fr-extension")] }
+    assert_equal "Invalid plugin name my_plugin-31fr-extension. Please give a name which does not contain a namespace starting with numeric characters.\n", content
 
     content = capture(:stderr){ run_generator [File.join(destination_root, "things4.3")] }
-    assert_equal "Invalid plugin name things4.3. Please give a name which use only alphabetic or numeric or \"_\" characters.\n", content
+    assert_equal "Invalid plugin name things4.3. Please give a name which uses only alphabetic, numeric, \"_\" or \"-\" characters.\n", content
 
     content = capture(:stderr){ run_generator [File.join(destination_root, "43things")] }
     assert_equal "Invalid plugin name 43things. Please give a name which does not start with numbers.\n", content
 
     content = capture(:stderr){ run_generator [File.join(destination_root, "plugin")] }
-    assert_equal "Invalid plugin name plugin. Please give a name which does not match one of the reserved rails words.\n", content
+    assert_equal "Invalid plugin name plugin. Please give a name which does not match one of the reserved rails words: application, destroy, plugin, runner, test\n", content
 
     content = capture(:stderr){ run_generator [File.join(destination_root, "Digest")] }
     assert_equal "Invalid plugin name Digest, constant Digest is already in use. Please choose another plugin name.\n", content
   end
 
-  def test_camelcase_plugin_name_underscores_filenames
+  def test_correct_file_in_lib_folder_of_hyphenated_plugin_name
+    run_generator [File.join(destination_root, "hyphenated-name")]
+    assert_no_file "hyphenated-name/lib/hyphenated-name.rb"
+    assert_no_file "hyphenated-name/lib/hyphenated_name.rb"
+    assert_file "hyphenated-name/lib/hyphenated/name.rb", /module Hyphenated\n  module Name\n    # Your code goes here...\n  end\nend/
+  end
+
+  def test_correct_file_in_lib_folder_of_camelcase_plugin_name
     run_generator [File.join(destination_root, "CamelCasedName")]
     assert_no_file "CamelCasedName/lib/CamelCasedName.rb"
     assert_file "CamelCasedName/lib/camel_cased_name.rb", /module CamelCasedName/
@@ -54,6 +60,7 @@ class PluginGeneratorTest < Rails::Generators::TestCase
     run_generator
     assert_file "README.rdoc", /Bukkits/
     assert_no_file "config/routes.rb"
+    assert_no_file "app/assets/config/bukkits_manifest.js"
     assert_file "test/test_helper.rb" do |content|
       assert_match(/require.+test\/dummy\/config\/environment/, content)
       assert_match(/ActiveRecord::Migrator\.migrations_paths.+test\/dummy\/db\/migrate/, content)
@@ -112,7 +119,7 @@ class PluginGeneratorTest < Rails::Generators::TestCase
 
   def test_ensure_that_test_dummy_can_be_generated_from_a_template
     FileUtils.cd(Rails.root)
-    run_generator([destination_root, "-m", "lib/create_test_dummy_template.rb", "--skip-test-unit"])
+    run_generator([destination_root, "-m", "lib/create_test_dummy_template.rb", "--skip-test"])
     assert_file "spec/dummy"
     assert_no_file "test"
   end
@@ -185,13 +192,11 @@ class PluginGeneratorTest < Rails::Generators::TestCase
 
   def test_generation_runs_bundle_install_with_full_and_mountable
     result = run_generator [destination_root, "--mountable", "--full", "--dev"]
+    assert_match(/run  bundle install/, result)
+    assert $?.success?, "Command failed: #{result}"
     assert_file "#{destination_root}/Gemfile.lock" do |contents|
       assert_match(/bukkits/, contents)
     end
-    assert_match(/run  bundle install/, result)
-    assert_match(/Using bukkits \(?0\.0\.1\)?/, result)
-    assert_match(/Your bundle is complete/, result)
-    assert_equal 1, result.scan("Your bundle is complete").size
   end
 
   def test_skipping_javascripts_without_mountable_option
@@ -252,6 +257,40 @@ class PluginGeneratorTest < Rails::Generators::TestCase
     assert_file "lib/bukkits.rb", /require "bukkits\/engine"/
   end
 
+  def test_creating_engine_with_hyphenated_name_in_full_mode
+    run_generator [File.join(destination_root, "hyphenated-name"), "--full"]
+    assert_file "hyphenated-name/app/assets/javascripts/hyphenated/name"
+    assert_file "hyphenated-name/app/assets/stylesheets/hyphenated/name"
+    assert_file "hyphenated-name/app/assets/images/hyphenated/name"
+    assert_file "hyphenated-name/app/models"
+    assert_file "hyphenated-name/app/controllers"
+    assert_file "hyphenated-name/app/views"
+    assert_file "hyphenated-name/app/helpers"
+    assert_file "hyphenated-name/app/mailers"
+    assert_file "hyphenated-name/bin/rails"
+    assert_file "hyphenated-name/config/routes.rb",              /Rails.application.routes.draw do/
+    assert_file "hyphenated-name/lib/hyphenated/name/engine.rb", /module Hyphenated\n  module Name\n    class Engine < ::Rails::Engine\n    end\n  end\nend/
+    assert_file "hyphenated-name/lib/hyphenated/name.rb",        /require "hyphenated\/name\/engine"/
+    assert_file "hyphenated-name/bin/rails",                     /\.\.\/\.\.\/lib\/hyphenated\/name\/engine/
+  end
+
+  def test_creating_engine_with_hyphenated_and_underscored_name_in_full_mode
+    run_generator [File.join(destination_root, "my_hyphenated-name"), "--full"]
+    assert_file "my_hyphenated-name/app/assets/javascripts/my_hyphenated/name"
+    assert_file "my_hyphenated-name/app/assets/stylesheets/my_hyphenated/name"
+    assert_file "my_hyphenated-name/app/assets/images/my_hyphenated/name"
+    assert_file "my_hyphenated-name/app/models"
+    assert_file "my_hyphenated-name/app/controllers"
+    assert_file "my_hyphenated-name/app/views"
+    assert_file "my_hyphenated-name/app/helpers"
+    assert_file "my_hyphenated-name/app/mailers"
+    assert_file "my_hyphenated-name/bin/rails"
+    assert_file "my_hyphenated-name/config/routes.rb",              /Rails.application.routes.draw do/
+    assert_file "my_hyphenated-name/lib/my_hyphenated/name/engine.rb", /module MyHyphenated\n  module Name\n    class Engine < ::Rails::Engine\n    end\n  end\nend/
+    assert_file "my_hyphenated-name/lib/my_hyphenated/name.rb",        /require "my_hyphenated\/name\/engine"/
+    assert_file "my_hyphenated-name/bin/rails",                     /\.\.\/\.\.\/lib\/my_hyphenated\/name\/engine/
+  end
+
   def test_being_quiet_while_creating_dummy_application
     assert_no_match(/create\s+config\/application.rb/, run_generator)
   end
@@ -265,6 +304,7 @@ class PluginGeneratorTest < Rails::Generators::TestCase
     assert_file "lib/bukkits/engine.rb", /isolate_namespace Bukkits/
     assert_file "test/dummy/config/routes.rb", /mount Bukkits::Engine => "\/bukkits"/
     assert_file "app/controllers/bukkits/application_controller.rb", /module Bukkits\n  class ApplicationController < ActionController::Base/
+    assert_file "app/jobs/bukkits/application_job.rb", /module Bukkits\n  class ApplicationJob < ActiveJob::Base/
     assert_file "app/helpers/bukkits/application_helper.rb", /module Bukkits\n  module ApplicationHelper/
     assert_file "app/views/layouts/bukkits/application.html.erb" do |contents|
       assert_match "<title>Bukkits</title>", contents
@@ -274,6 +314,67 @@ class PluginGeneratorTest < Rails::Generators::TestCase
     assert_file "test/test_helper.rb" do |content|
       assert_match(/ActiveRecord::Migrator\.migrations_paths.+\.\.\/test\/dummy\/db\/migrate/, content)
       assert_match(/ActiveRecord::Migrator\.migrations_paths.+<<.+\.\.\/db\/migrate/, content)
+      assert_match(/ActionDispatch::IntegrationTest\.fixture_path = ActiveSupport::TestCase\.fixture_pat/, content)
+    end
+  end
+
+  def test_create_mountable_application_with_mountable_option_and_hypenated_name
+    run_generator [File.join(destination_root, "hyphenated-name"), "--mountable"]
+    assert_file "hyphenated-name/app/assets/javascripts/hyphenated/name"
+    assert_file "hyphenated-name/app/assets/stylesheets/hyphenated/name"
+    assert_file "hyphenated-name/app/assets/images/hyphenated/name"
+    assert_file "hyphenated-name/config/routes.rb",                                          /Hyphenated::Name::Engine.routes.draw do/
+    assert_file "hyphenated-name/lib/hyphenated/name/version.rb",                            /module Hyphenated\n  module Name\n    VERSION = '0.1.0'\n  end\nend/
+    assert_file "hyphenated-name/lib/hyphenated/name/engine.rb",                             /module Hyphenated\n  module Name\n    class Engine < ::Rails::Engine\n      isolate_namespace Hyphenated::Name\n    end\n  end\nend/
+    assert_file "hyphenated-name/lib/hyphenated/name.rb",                                    /require "hyphenated\/name\/engine"/
+    assert_file "hyphenated-name/test/dummy/config/routes.rb",                               /mount Hyphenated::Name::Engine => "\/hyphenated-name"/
+    assert_file "hyphenated-name/app/controllers/hyphenated/name/application_controller.rb", /module Hyphenated\n  module Name\n    class ApplicationController < ActionController::Base\n    end\n  end\nend/
+    assert_file "hyphenated-name/app/jobs/hyphenated/name/application_job.rb", /module Hyphenated\n  module Name\n    class ApplicationJob < ActiveJob::Base/
+    assert_file "hyphenated-name/app/helpers/hyphenated/name/application_helper.rb",         /module Hyphenated\n  module Name\n    module ApplicationHelper\n    end\n  end\nend/
+    assert_file "hyphenated-name/app/views/layouts/hyphenated/name/application.html.erb" do |contents|
+      assert_match "<title>Hyphenated name</title>", contents
+      assert_match(/stylesheet_link_tag\s+['"]hyphenated\/name\/application['"]/, contents)
+      assert_match(/javascript_include_tag\s+['"]hyphenated\/name\/application['"]/, contents)
+    end
+  end
+
+  def test_create_mountable_application_with_mountable_option_and_hypenated_and_underscored_name
+    run_generator [File.join(destination_root, "my_hyphenated-name"), "--mountable"]
+    assert_file "my_hyphenated-name/app/assets/javascripts/my_hyphenated/name"
+    assert_file "my_hyphenated-name/app/assets/stylesheets/my_hyphenated/name"
+    assert_file "my_hyphenated-name/app/assets/images/my_hyphenated/name"
+    assert_file "my_hyphenated-name/config/routes.rb",                                             /MyHyphenated::Name::Engine.routes.draw do/
+    assert_file "my_hyphenated-name/lib/my_hyphenated/name/version.rb",                            /module MyHyphenated\n  module Name\n    VERSION = '0.1.0'\n  end\nend/
+    assert_file "my_hyphenated-name/lib/my_hyphenated/name/engine.rb",                             /module MyHyphenated\n  module Name\n    class Engine < ::Rails::Engine\n      isolate_namespace MyHyphenated::Name\n    end\n  end\nend/
+    assert_file "my_hyphenated-name/lib/my_hyphenated/name.rb",                                    /require "my_hyphenated\/name\/engine"/
+    assert_file "my_hyphenated-name/test/dummy/config/routes.rb",                                  /mount MyHyphenated::Name::Engine => "\/my_hyphenated-name"/
+    assert_file "my_hyphenated-name/app/controllers/my_hyphenated/name/application_controller.rb", /module MyHyphenated\n  module Name\n    class ApplicationController < ActionController::Base\n    end\n  end\nend/
+    assert_file "my_hyphenated-name/app/jobs/my_hyphenated/name/application_job.rb", /module MyHyphenated\n  module Name\n    class ApplicationJob < ActiveJob::Base/
+    assert_file "my_hyphenated-name/app/helpers/my_hyphenated/name/application_helper.rb",         /module MyHyphenated\n  module Name\n    module ApplicationHelper\n    end\n  end\nend/
+    assert_file "my_hyphenated-name/app/views/layouts/my_hyphenated/name/application.html.erb" do |contents|
+      assert_match "<title>My hyphenated name</title>", contents
+      assert_match(/stylesheet_link_tag\s+['"]my_hyphenated\/name\/application['"]/, contents)
+      assert_match(/javascript_include_tag\s+['"]my_hyphenated\/name\/application['"]/, contents)
+    end
+  end
+
+  def test_create_mountable_application_with_mountable_option_and_multiple_hypenates_in_name
+    run_generator [File.join(destination_root, "deep-hyphenated-name"), "--mountable"]
+    assert_file "deep-hyphenated-name/app/assets/javascripts/deep/hyphenated/name"
+    assert_file "deep-hyphenated-name/app/assets/stylesheets/deep/hyphenated/name"
+    assert_file "deep-hyphenated-name/app/assets/images/deep/hyphenated/name"
+    assert_file "deep-hyphenated-name/config/routes.rb",                                               /Deep::Hyphenated::Name::Engine.routes.draw do/
+    assert_file "deep-hyphenated-name/lib/deep/hyphenated/name/version.rb",                            /module Deep\n  module Hyphenated\n    module Name\n      VERSION = '0.1.0'\n    end\n  end\nend/
+    assert_file "deep-hyphenated-name/lib/deep/hyphenated/name/engine.rb",                             /module Deep\n  module Hyphenated\n    module Name\n      class Engine < ::Rails::Engine\n        isolate_namespace Deep::Hyphenated::Name\n      end\n    end\n  end\nend/
+    assert_file "deep-hyphenated-name/lib/deep/hyphenated/name.rb",                                    /require "deep\/hyphenated\/name\/engine"/
+    assert_file "deep-hyphenated-name/test/dummy/config/routes.rb",                                    /mount Deep::Hyphenated::Name::Engine => "\/deep-hyphenated-name"/
+    assert_file "deep-hyphenated-name/app/controllers/deep/hyphenated/name/application_controller.rb", /module Deep\n  module Hyphenated\n    module Name\n      class ApplicationController < ActionController::Base\n      end\n    end\n  end\nend/
+    assert_file "deep-hyphenated-name/app/jobs/deep/hyphenated/name/application_job.rb", /module Deep\n  module Hyphenated\n    module Name\n      class ApplicationJob < ActiveJob::Base/
+    assert_file "deep-hyphenated-name/app/helpers/deep/hyphenated/name/application_helper.rb",         /module Deep\n  module Hyphenated\n    module Name\n      module ApplicationHelper\n      end\n    end\n  end\nend/
+    assert_file "deep-hyphenated-name/app/views/layouts/deep/hyphenated/name/application.html.erb" do |contents|
+      assert_match "<title>Deep hyphenated name</title>", contents
+      assert_match(/stylesheet_link_tag\s+['"]deep\/hyphenated\/name\/application['"]/, contents)
+      assert_match(/javascript_include_tag\s+['"]deep\/hyphenated\/name\/application['"]/, contents)
     end
   end
 
@@ -321,7 +422,7 @@ class PluginGeneratorTest < Rails::Generators::TestCase
   end
 
   def test_creating_dummy_without_tests_but_with_dummy_path
-    run_generator [destination_root, "--dummy_path", "spec/dummy", "--skip-test-unit"]
+    run_generator [destination_root, "--dummy_path", "spec/dummy", "--skip-test"]
     assert_file "spec/dummy"
     assert_file "spec/dummy/config/application.rb"
     assert_no_file "test"
@@ -333,14 +434,27 @@ class PluginGeneratorTest < Rails::Generators::TestCase
 
   def test_ensure_that_gitignore_can_be_generated_from_a_template_for_dummy_path
     FileUtils.cd(Rails.root)
-    run_generator([destination_root, "--dummy_path", "spec/dummy", "--skip-test-unit"])
+    run_generator([destination_root, "--dummy_path", "spec/dummy", "--skip-test"])
     assert_file ".gitignore" do |contents|
       assert_match(/spec\/dummy/, contents)
     end
   end
 
-  def test_skipping_test_unit
-    run_generator [destination_root, "--skip-test-unit"]
+  def test_unnecessary_files_are_not_generated_in_dummy_application
+    run_generator
+    assert_no_file 'test/dummy/.gitignore'
+    assert_no_file 'test/dummy/db/seeds.rb'
+    assert_no_file 'test/dummy/Gemfile'
+    assert_no_file 'test/dummy/public/robots.txt'
+    assert_no_file 'test/dummy/README.md'
+    assert_no_directory 'test/dummy/lib/tasks'
+    assert_no_directory 'test/dummy/doc'
+    assert_no_directory 'test/dummy/test'
+    assert_no_directory 'test/dummy/vendor'
+  end
+
+  def test_skipping_test_files
+    run_generator [destination_root, "--skip-test"]
     assert_no_file "test"
     assert_file "bukkits.gemspec" do |contents|
       assert_no_match(/s.test_files = Dir\["test\/\*\*\/\*"\]/, contents)
@@ -448,6 +562,60 @@ class PluginGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_skipping_useless_folders_generation_for_api_engines
+    ['--full', '--mountable'].each do |option|
+      run_generator [destination_root, option, '--api']
+
+      assert_no_directory "app/assets"
+      assert_no_directory "app/helpers"
+      assert_no_directory "app/views"
+
+      FileUtils.rm_rf destination_root
+    end
+  end
+
+  def test_application_controller_parent_for_mountable_api_plugins
+    run_generator [destination_root, '--mountable', '--api']
+
+    assert_file "app/controllers/bukkits/application_controller.rb" do |content|
+      assert_match "ApplicationController < ActionController::API", content
+    end
+  end
+
+  def test_dummy_api_application_for_api_plugins
+    run_generator [destination_root, '--api']
+
+    assert_file "test/dummy/config/application.rb" do |content|
+      assert_match "config.api_only = true", content
+    end
+  end
+
+
+  def test_api_generators_configuration_for_api_engines
+    run_generator [destination_root, '--full', '--api']
+
+    assert_file "lib/bukkits/engine.rb" do |content|
+      assert_match "config.generators.api_only = true", content
+    end
+  end
+
+  def test_scaffold_generator_for_mountable_api_plugins
+    run_generator [destination_root, '--mountable', '--api']
+
+    capture(:stdout) do
+      `#{destination_root}/bin/rails g scaffold article`
+    end
+
+    assert_file "app/models/bukkits/article.rb"
+    assert_file "app/controllers/bukkits/articles_controller.rb" do |content|
+      assert_match "only: [:show, :update, :destroy]", content
+    end
+
+    assert_no_directory "app/assets"
+    assert_no_directory "app/helpers"
+    assert_no_directory "app/views"
+  end
+
 protected
   def action(*args, &block)
     silence(:stdout){ generator.send(*args, &block) }
diff --git a/railties/test/generators/scaffold_controller_generator_test.rb b/railties/test/generators/scaffold_controller_generator_test.rb
index ca972a3bdd..95ef853a11 100644
--- a/railties/test/generators/scaffold_controller_generator_test.rb
+++ b/railties/test/generators/scaffold_controller_generator_test.rb
@@ -106,8 +106,8 @@ class ScaffoldControllerGeneratorTest < Rails::Generators::TestCase
     assert_file "test/controllers/users_controller_test.rb" do |content|
       assert_match(/class UsersControllerTest < ActionController::TestCase/, content)
       assert_match(/test "should get index"/, content)
-      assert_match(/post :create, user: \{ age: @user\.age, name: @user\.name, organization_id: @user\.organization_id, organization_type: @user\.organization_type \}/, content)
-      assert_match(/patch :update, id: @user, user: \{ age: @user\.age, name: @user\.name, organization_id: @user\.organization_id, organization_type: @user\.organization_type \}/, content)
+      assert_match(/post :create, params: \{ user: \{ age: @user\.age, name: @user\.name, organization_id: @user\.organization_id, organization_type: @user\.organization_type \} \}/, content)
+      assert_match(/patch :update, params: \{ id: @user, user: \{ age: @user\.age, name: @user\.name, organization_id: @user\.organization_id, organization_type: @user\.organization_type \} \}/, content)
     end
   end
 
@@ -117,8 +117,8 @@ class ScaffoldControllerGeneratorTest < Rails::Generators::TestCase
     assert_file "test/controllers/users_controller_test.rb" do |content|
       assert_match(/class UsersControllerTest < ActionController::TestCase/, content)
       assert_match(/test "should get index"/, content)
-      assert_match(/post :create, user: \{  \}/, content)
-      assert_match(/patch :update, id: @user, user: \{  \}/, content)
+      assert_match(/post :create, params: \{ user: \{  \} \}/, content)
+      assert_match(/patch :update, params: \{ id: @user, user: \{  \} \}/, content)
     end
   end
 
@@ -174,4 +174,73 @@ class ScaffoldControllerGeneratorTest < Rails::Generators::TestCase
       end
     end
   end
+
+  def test_controller_tests_pass_by_default_inside_mountable_engine
+    Dir.chdir(destination_root) { `bundle exec rails plugin new bukkits --mountable` }
+
+    engine_path = File.join(destination_root, "bukkits")
+
+    Dir.chdir(engine_path) do
+      quietly { `bin/rails g controller dashboard foo` }
+      assert_match(/2 runs, 2 assertions, 0 failures, 0 errors/, `bin/rails test 2>&1`)
+    end
+  end
+
+  def test_controller_tests_pass_by_default_inside_full_engine
+    Dir.chdir(destination_root) { `bundle exec rails plugin new bukkits --full` }
+
+    engine_path = File.join(destination_root, "bukkits")
+
+    Dir.chdir(engine_path) do
+      quietly { `bin/rails g controller dashboard foo` }
+      assert_match(/2 runs, 2 assertions, 0 failures, 0 errors/, `bin/rails test 2>&1`)
+    end
+  end
+
+  def test_api_only_generates_a_proper_api_controller
+    run_generator ["User", "--api"]
+
+    assert_file "app/controllers/users_controller.rb" do |content|
+      assert_match(/class UsersController < ApplicationController/, content)
+      assert_no_match(/respond_to/, content)
+
+      assert_match(/before_action :set_user, only: \[:show, :update, :destroy\]/, content)
+
+      assert_instance_method :index, content do |m|
+        assert_match(/@users = User\.all/, m)
+        assert_match(/render json: @users/, m)
+      end
+
+      assert_instance_method :show, content do |m|
+        assert_match(/render json: @user/, m)
+      end
+
+      assert_instance_method :create, content do |m|
+        assert_match(/@user = User\.new\(user_params\)/, m)
+        assert_match(/@user\.save/, m)
+        assert_match(/@user\.errors/, m)
+      end
+
+      assert_instance_method :update, content do |m|
+        assert_match(/@user\.update\(user_params\)/, m)
+        assert_match(/@user\.errors/, m)
+      end
+
+      assert_instance_method :destroy, content do |m|
+        assert_match(/@user\.destroy/, m)
+      end
+    end
+  end
+
+  def test_api_controller_tests
+    run_generator ["User", "name:string", "age:integer", "organization:references{polymorphic}", "--api"]
+
+    assert_file "test/controllers/users_controller_test.rb" do |content|
+      assert_match(/class UsersControllerTest < ActionController::TestCase/, content)
+      assert_match(/test "should get index"/, content)
+      assert_match(/post :create, params: \{ user: \{ age: @user\.age, name: @user\.name, organization_id: @user\.organization_id, organization_type: @user\.organization_type \} \}/, content)
+      assert_match(/patch :update, params: \{ id: @user, user: \{ age: @user\.age, name: @user\.name, organization_id: @user\.organization_id, organization_type: @user\.organization_type \} \}/, content)
+      assert_no_match(/assert_redirected_to/, content)
+    end
+  end
 end
diff --git a/railties/test/generators/scaffold_generator_test.rb b/railties/test/generators/scaffold_generator_test.rb
index 3b545328b5..0c3808a9a0 100644
--- a/railties/test/generators/scaffold_generator_test.rb
+++ b/railties/test/generators/scaffold_generator_test.rb
@@ -58,8 +58,8 @@ class ScaffoldGeneratorTest < Rails::Generators::TestCase
 
     assert_file "test/controllers/product_lines_controller_test.rb" do |test|
       assert_match(/class ProductLinesControllerTest < ActionController::TestCase/, test)
-      assert_match(/post :create, product_line: \{ product_id: @product_line\.product_id, title: @product_line\.title, user_id: @product_line\.user_id \}/, test)
-      assert_match(/patch :update, id: @product_line, product_line: \{ product_id: @product_line\.product_id, title: @product_line\.title, user_id: @product_line\.user_id \}/, test)
+      assert_match(/post :create, params: \{ product_line: \{ product_id: @product_line\.product_id, title: @product_line\.title, user_id: @product_line\.user_id \} \}/, test)
+      assert_match(/patch :update, params: \{ id: @product_line, product_line: \{ product_id: @product_line\.product_id, title: @product_line\.title, user_id: @product_line\.user_id \} \}/, test)
     end
 
     # Views
@@ -87,14 +87,84 @@ class ScaffoldGeneratorTest < Rails::Generators::TestCase
     assert_file "app/assets/stylesheets/product_lines.css"
   end
 
+  def test_api_scaffold_on_invoke
+    run_generator %w(product_line title:string product:belongs_to user:references --api --no-template-engine --no-helper --no-assets)
+
+    # Model
+    assert_file "app/models/product_line.rb", /class ProductLine < ActiveRecord::Base/
+    assert_file "test/models/product_line_test.rb", /class ProductLineTest < ActiveSupport::TestCase/
+    assert_file "test/fixtures/product_lines.yml"
+    assert_migration "db/migrate/create_product_lines.rb", /belongs_to :product, index: true/
+    assert_migration "db/migrate/create_product_lines.rb", /references :user, index: true/
+
+    # Route
+    assert_file "config/routes.rb" do |route|
+      assert_match(/resources :product_lines$/, route)
+    end
+
+    # Controller
+    assert_file "app/controllers/product_lines_controller.rb" do |content|
+      assert_match(/class ProductLinesController < ApplicationController/, content)
+      assert_no_match(/respond_to/, content)
+
+      assert_match(/before_action :set_product_line, only: \[:show, :update, :destroy\]/, content)
+
+      assert_instance_method :index, content do |m|
+        assert_match(/@product_lines = ProductLine\.all/, m)
+        assert_match(/render json: @product_lines/, m)
+      end
+
+      assert_instance_method :show, content do |m|
+        assert_match(/render json: @product_line/, m)
+      end
+
+      assert_instance_method :create, content do |m|
+        assert_match(/@product_line = ProductLine\.new\(product_line_params\)/, m)
+        assert_match(/@product_line\.save/, m)
+        assert_match(/@product_line\.errors/, m)
+      end
+
+      assert_instance_method :update, content do |m|
+        assert_match(/@product_line\.update\(product_line_params\)/, m)
+        assert_match(/@product_line\.errors/, m)
+      end
+
+      assert_instance_method :destroy, content do |m|
+        assert_match(/@product_line\.destroy/, m)
+      end
+    end
+
+    assert_file "test/controllers/product_lines_controller_test.rb" do |test|
+      assert_match(/class ProductLinesControllerTest < ActionController::TestCase/, test)
+      assert_match(/post :create, params: \{ product_line: \{ product_id: @product_line\.product_id, title: @product_line\.title, user_id: @product_line\.user_id \} \}/, test)
+      assert_match(/patch :update, params: \{ id: @product_line, product_line: \{ product_id: @product_line\.product_id, title: @product_line\.title, user_id: @product_line\.user_id \} \}/, test)
+      assert_no_match(/assert_redirected_to/, test)
+    end
+
+    # Views
+    assert_no_file "app/views/layouts/product_lines.html.erb"
+
+    %w(index show new edit _form).each do |view|
+      assert_no_file "app/views/product_lines/#{view}.html.erb"
+    end
+
+    # Helpers
+    assert_no_file "app/helpers/product_lines_helper.rb"
+
+    # Assets
+    assert_no_file "app/assets/stylesheets/scaffold.css"
+    assert_no_file "app/assets/javascripts/product_lines.js"
+    assert_no_file "app/assets/stylesheets/product_lines.css"
+  end
+
   def test_functional_tests_without_attributes
     run_generator ["product_line"]
 
     assert_file "test/controllers/product_lines_controller_test.rb" do |content|
       assert_match(/class ProductLinesControllerTest < ActionController::TestCase/, content)
       assert_match(/test "should get index"/, content)
-      assert_match(/post :create, product_line: \{  \}/, content)
-      assert_match(/patch :update, id: @product_line, product_line: \{  \}/, content)
+      assert_match(/post :create, params: \{ product_line: \{  \} \}/, content)
+      assert_match(/patch :update, params: \{ id: @product_line, product_line: \{  \} \}/, content)
     end
   end
 
@@ -245,6 +315,29 @@ class ScaffoldGeneratorTest < Rails::Generators::TestCase
     assert_file "config/routes.rb", /\.routes\.draw do\s*\|map\|\s*$/
   end
 
+  def test_scaffold_generator_on_revoke_does_not_mutilate_routes
+    run_generator
+
+    route_path = File.expand_path("config/routes.rb", destination_root)
+    content = File.read(route_path)
+
+    # Remove all of the comments and blank lines from the routes file
+    content.gsub!(/^  \#.*\n/, '')
+    content.gsub!(/^\n/, '')
+
+    File.open(route_path, "wb") { |file| file.write(content) }
+    assert_file "config/routes.rb", /\.routes\.draw do\n  resources :product_lines\nend\n\z/
+
+    run_generator ["product_line"], :behavior => :revoke
+
+    assert_file "config/routes.rb", /\.routes\.draw do\nend\n\z/
+  end
+
+  def test_scaffold_generator_ignores_commented_routes
+    run_generator ["product"]
+    assert_file "config/routes.rb", /\.routes\.draw do\n  resources :products\n/
+  end
+
   def test_scaffold_generator_no_assets_with_switch_no_assets
     run_generator [ "posts", "--no-assets" ]
     assert_no_file "app/assets/stylesheets/scaffold.css"
@@ -259,6 +352,20 @@ class ScaffoldGeneratorTest < Rails::Generators::TestCase
     assert_no_file "app/assets/stylesheets/posts.css"
   end
 
+  def test_scaffold_generator_no_scaffold_stylesheet_with_switch_no_scaffold_stylesheet
+    run_generator [ "posts", "--no-scaffold-stylesheet" ]
+    assert_no_file "app/assets/stylesheets/scaffold.css"
+    assert_file "app/assets/javascripts/posts.js"
+    assert_file "app/assets/stylesheets/posts.css"
+  end
+
+  def test_scaffold_generator_no_scaffold_stylesheet_with_switch_scaffold_stylesheet_false
+    run_generator [ "posts", "--scaffold-stylesheet=false" ]
+    assert_no_file "app/assets/stylesheets/scaffold.css"
+    assert_file "app/assets/javascripts/posts.js"
+    assert_file "app/assets/stylesheets/posts.css"
+  end
+
   def test_scaffold_generator_with_switch_resource_route_false
     run_generator [ "posts", "--resource-route=false" ]
     assert_file "config/routes.rb" do |route|
@@ -370,4 +477,60 @@ class ScaffoldGeneratorTest < Rails::Generators::TestCase
       assert_match(/password_digest: <%= BCrypt::Password.create\('secret'\) %>/, content)
     end
   end
+
+  def test_scaffold_tests_pass_by_default_inside_mountable_engine
+    Dir.chdir(destination_root) { `bundle exec rails plugin new bukkits --mountable` }
+
+    engine_path = File.join(destination_root, "bukkits")
+
+    Dir.chdir(engine_path) do
+      quietly do
+        `bin/rails g scaffold User name:string age:integer;
+        bundle exec rake db:migrate`
+      end
+      assert_match(/8 runs, 13 assertions, 0 failures, 0 errors/, `bin/rails test 2>&1`)
+    end
+  end
+
+  def test_scaffold_tests_pass_by_default_inside_full_engine
+    Dir.chdir(destination_root) { `bundle exec rails plugin new bukkits --full` }
+
+    engine_path = File.join(destination_root, "bukkits")
+
+    Dir.chdir(engine_path) do
+      quietly do
+        `bin/rails g scaffold User name:string age:integer;
+        bundle exec rake db:migrate`
+      end
+      assert_match(/8 runs, 13 assertions, 0 failures, 0 errors/, `bin/rails test 2>&1`)
+    end
+  end
+
+  def test_scaffold_tests_pass_by_default_inside_api_mountable_engine
+    Dir.chdir(destination_root) { `bundle exec rails plugin new bukkits --mountable --api` }
+
+    engine_path = File.join(destination_root, "bukkits")
+
+    Dir.chdir(engine_path) do
+      quietly do
+        `bin/rails g scaffold User name:string age:integer;
+        bundle exec rake db:migrate`
+      end
+      assert_match(/6 runs, 8 assertions, 0 failures, 0 errors/, `bin/rails test 2>&1`)
+    end
+  end
+
+  def test_scaffold_tests_pass_by_default_inside_api_full_engine
+    Dir.chdir(destination_root) { `bundle exec rails plugin new bukkits --full --api` }
+
+    engine_path = File.join(destination_root, "bukkits")
+
+    Dir.chdir(engine_path) do
+      quietly do
+        `bin/rails g scaffold User name:string age:integer;
+        bundle exec rake db:migrate`
+      end
+      assert_match(/6 runs, 8 assertions, 0 failures, 0 errors/, `bin/rails test 2>&1`)
+    end
+  end
 end
diff --git a/railties/test/generators/shared_generator_tests.rb b/railties/test/generators/shared_generator_tests.rb
index b998fef42e..acb78ec888 100644
--- a/railties/test/generators/shared_generator_tests.rb
+++ b/railties/test/generators/shared_generator_tests.rb
@@ -28,9 +28,22 @@ module SharedGeneratorTests
 
   def assert_generates_with_bundler(options = {})
     generator([destination_root], options)
-    generator.expects(:bundle_command).with('install').once
-    generator.stubs(:bundle_command).with('exec spring binstub --all')
-    quietly { generator.invoke_all }
+
+    command_check = -> command do
+      @install_called ||= 0
+
+      case command
+      when 'install'
+        @install_called += 1
+        assert_equal 1, @install_called, "install expected to be called once, but was called #{@install_called} times"
+      when 'exec spring binstub --all'
+        # Called when running tests with spring, let through unscathed.
+      end
+    end
+
+    generator.stub :bundle_command, command_check do
+      quietly { generator.invoke_all }
+    end
   end
 
   def test_generation_runs_bundle_install
@@ -47,8 +60,8 @@ module SharedGeneratorTests
     assert_match(/Invalid value for \-\-database option/, content)
   end
 
-  def test_test_unit_is_skipped_if_required
-    run_generator [destination_root, "--skip-test-unit"]
+  def test_test_files_are_skipped_if_required
+    run_generator [destination_root, "--skip-test"]
     assert_no_file "test"
   end
 
@@ -56,7 +69,7 @@ module SharedGeneratorTests
     reserved_words = %w[application destroy plugin runner test]
     reserved_words.each do |reserved|
       content = capture(:stderr){ run_generator [File.join(destination_root, reserved)] }
-      assert_match(/Invalid \w+ name #{reserved}. Please give a name which does not match one of the reserved rails words.\n/, content)
+      assert_match(/Invalid \w+ name #{reserved}. Please give a name which does not match one of the reserved rails words: application, destroy, plugin, runner, test\n/, content)
     end
   end
 
@@ -86,22 +99,19 @@ module SharedGeneratorTests
     end
   end
 
-  def test_template_is_executed_when_supplied
-    path = "https://gist.github.com/josevalim/103208/raw/"
-    template = %{ say "It works!" }
-    template.instance_eval "def read; self; end" # Make the string respond to read
-
-    generator([destination_root], template: path).expects(:open).with(path, 'Accept' => 'application/x-thor-template').returns(template)
-    quietly { assert_match(/It works!/, capture(:stdout) { generator.invoke_all }) }
-  end
-
   def test_template_is_executed_when_supplied_an_https_path
     path = "https://gist.github.com/josevalim/103208/raw/"
     template = %{ say "It works!" }
     template.instance_eval "def read; self; end" # Make the string respond to read
 
-    generator([destination_root], template: path).expects(:open).with(path, 'Accept' => 'application/x-thor-template').returns(template)
-    quietly { assert_match(/It works!/, capture(:stdout) { generator.invoke_all }) }
+    check_open = -> *args do
+      assert_equal [ path, 'Accept' => 'application/x-thor-template' ], args
+      template
+    end
+
+    generator([destination_root], template: path).stub(:open, check_open, template) do
+      quietly { assert_match(/It works!/, capture(:stdout) { generator.invoke_all }) }
+    end
   end
 
   def test_dev_option
@@ -116,18 +126,19 @@ module SharedGeneratorTests
   end
 
   def test_skip_gemfile
-    generator([destination_root], skip_gemfile: true).expects(:bundle_command).never
-    quietly { generator.invoke_all }
-    assert_no_file 'Gemfile'
+    assert_not_called(generator([destination_root], skip_gemfile: true), :bundle_command) do
+      quietly { generator.invoke_all }
+      assert_no_file 'Gemfile'
+    end
   end
 
   def test_skip_bundle
-    generator([destination_root], skip_bundle: true).expects(:bundle_command).never
-    quietly { generator.invoke_all }
-
-    # skip_bundle is only about running bundle install, ensure the Gemfile is still
-    # generated.
-    assert_file 'Gemfile'
+    assert_not_called(generator([destination_root], skip_bundle: true), :bundle_command) do
+      quietly { generator.invoke_all }
+      # skip_bundle is only about running bundle install, ensure the Gemfile is still
+      # generated.
+      assert_file 'Gemfile'
+    end
   end
 
   def test_skip_git
@@ -138,7 +149,11 @@ module SharedGeneratorTests
 
   def test_skip_keeps
     run_generator [destination_root, '--skip-keeps', '--full']
-    assert_file('.gitignore')
+
+    assert_file '.gitignore' do |content|
+      assert_no_match(/\.keep/, content)
+    end
+
     assert_no_file('app/mailers/.keep')
   end
 end
diff --git a/railties/test/generators_test.rb b/railties/test/generators_test.rb
index 127e059bf1..291415858c 100644
--- a/railties/test/generators_test.rb
+++ b/railties/test/generators_test.rb
@@ -1,7 +1,6 @@
 require 'generators/generators_test_helper'
 require 'rails/generators/rails/model/model_generator'
 require 'rails/generators/test_unit/model/model_generator'
-require 'mocha/setup' # FIXME: stop using mocha
 
 class GeneratorsTest < Rails::Generators::TestCase
   include GeneratorsTestHelper
@@ -17,8 +16,9 @@ class GeneratorsTest < Rails::Generators::TestCase
 
   def test_simple_invoke
     assert File.exist?(File.join(@path, 'generators', 'model_generator.rb'))
-    TestUnit::Generators::ModelGenerator.expects(:start).with(["Account"], {})
-    Rails::Generators.invoke("test_unit:model", ["Account"])
+    assert_called_with(TestUnit::Generators::ModelGenerator, :start, [["Account"], {}]) do
+      Rails::Generators.invoke("test_unit:model", ["Account"])
+    end
   end
 
   def test_invoke_when_generator_is_not_found
@@ -34,6 +34,12 @@ class GeneratorsTest < Rails::Generators::TestCase
     assert_match "Maybe you meant 'migration'", output
   end
 
+  def test_generator_multiple_suggestions
+    name = :tas
+    output = capture(:stdout){ Rails::Generators.invoke name }
+    assert_match "Maybe you meant 'task', 'job' or", output
+  end
+
   def test_help_when_a_generator_with_required_arguments_is_invoked_without_arguments
     output = capture(:stdout){ Rails::Generators.invoke :model, [] }
     assert_match(/Description:/, output)
@@ -41,19 +47,22 @@ class GeneratorsTest < Rails::Generators::TestCase
 
   def test_should_give_higher_preference_to_rails_generators
     assert File.exist?(File.join(@path, 'generators', 'model_generator.rb'))
-    Rails::Generators::ModelGenerator.expects(:start).with(["Account"], {})
-    warnings = capture(:stderr){ Rails::Generators.invoke :model, ["Account"] }
-    assert warnings.empty?
+    assert_called_with(Rails::Generators::ModelGenerator, :start, [["Account"], {}]) do
+      warnings = capture(:stderr){ Rails::Generators.invoke :model, ["Account"] }
+      assert warnings.empty?
+    end
   end
 
   def test_invoke_with_default_values
-    Rails::Generators::ModelGenerator.expects(:start).with(["Account"], {})
-    Rails::Generators.invoke :model, ["Account"]
+    assert_called_with(Rails::Generators::ModelGenerator, :start, [["Account"], {}]) do
+      Rails::Generators.invoke :model, ["Account"]
+    end
   end
 
   def test_invoke_with_config_values
-    Rails::Generators::ModelGenerator.expects(:start).with(["Account"], behavior: :skip)
-    Rails::Generators.invoke :model, ["Account"], behavior: :skip
+    assert_called_with(Rails::Generators::ModelGenerator, :start, [["Account"], behavior: :skip]) do
+      Rails::Generators.invoke :model, ["Account"], behavior: :skip
+    end
   end
 
   def test_find_by_namespace
@@ -97,11 +106,12 @@ class GeneratorsTest < Rails::Generators::TestCase
   end
 
   def test_invoke_with_nested_namespaces
-    model_generator = mock('ModelGenerator') do
-      expects(:start).with(["Account"], {})
+    model_generator = Minitest::Mock.new
+    model_generator.expect(:start, nil, [["Account"], {}])
+    assert_called_with(Rails::Generators, :find_by_namespace, ['namespace', 'my:awesome'], returns: model_generator) do
+      Rails::Generators.invoke 'my:awesome:namespace', ["Account"]
     end
-    Rails::Generators.expects(:find_by_namespace).with('namespace', 'my:awesome').returns(model_generator)
-    Rails::Generators.invoke 'my:awesome:namespace', ["Account"]
+    model_generator.verify
   end
 
   def test_rails_generators_help_with_builtin_information
@@ -167,8 +177,9 @@ class GeneratorsTest < Rails::Generators::TestCase
 
   def test_fallbacks_for_generators_on_invoke
     Rails::Generators.fallbacks[:shoulda] = :test_unit
-    TestUnit::Generators::ModelGenerator.expects(:start).with(["Account"], {})
-    Rails::Generators.invoke "shoulda:model", ["Account"]
+    assert_called_with(TestUnit::Generators::ModelGenerator, :start, [["Account"], {}]) do
+      Rails::Generators.invoke "shoulda:model", ["Account"]
+    end
   ensure
     Rails::Generators.fallbacks.delete(:shoulda)
   end
@@ -176,8 +187,9 @@ class GeneratorsTest < Rails::Generators::TestCase
   def test_nested_fallbacks_for_generators
     Rails::Generators.fallbacks[:shoulda] = :test_unit
     Rails::Generators.fallbacks[:super_shoulda] = :shoulda
-    TestUnit::Generators::ModelGenerator.expects(:start).with(["Account"], {})
-    Rails::Generators.invoke "super_shoulda:model", ["Account"]
+    assert_called_with(TestUnit::Generators::ModelGenerator, :start, [["Account"], {}]) do
+      Rails::Generators.invoke "super_shoulda:model", ["Account"]
+    end
   ensure
     Rails::Generators.fallbacks.delete(:shoulda)
     Rails::Generators.fallbacks.delete(:super_shoulda)
diff --git a/railties/test/isolation/abstract_unit.rb b/railties/test/isolation/abstract_unit.rb
index 17c3f979c0..df3c2ca66d 100644
--- a/railties/test/isolation/abstract_unit.rb
+++ b/railties/test/isolation/abstract_unit.rb
@@ -11,6 +11,7 @@ require 'fileutils'
 require 'bundler/setup' unless defined?(Bundler)
 require 'active_support'
 require 'active_support/testing/autorun'
+require 'active_support/testing/stream'
 require 'active_support/test_case'
 
 RAILS_FRAMEWORK_ROOT = File.expand_path("#{File.dirname(__FILE__)}/../../..")
@@ -50,7 +51,12 @@ module TestHelpers
       old_env = ENV["RAILS_ENV"]
       @app ||= begin
         ENV["RAILS_ENV"] = env
-        require "#{app_path}/config/environment"
+
+        # FIXME: shush Sass warning spam, not relevant to testing Railties
+        Kernel.silence_warnings do
+          require "#{app_path}/config/environment"
+        end
+
         Rails.application
       end
     ensure
@@ -69,7 +75,8 @@ module TestHelpers
 
     def assert_welcome(resp)
       assert_equal 200, resp[0]
-      assert resp[1]["Content-Type"] = "text/html"
+      assert_match 'text/html', resp[1]["Content-Type"]
+      assert_match 'charset=utf-8', resp[1]["Content-Type"]
       assert extract_body(resp).match(/Welcome aboard/)
     end
 
@@ -157,19 +164,20 @@ module TestHelpers
       require "rails"
       require "action_controller/railtie"
       require "action_view/railtie"
+      require 'action_dispatch/middleware/flash'
 
-      app = Class.new(Rails::Application)
-      app.config.eager_load = false
-      app.secrets.secret_key_base = "3b7cd727ee24e8444053437c36cc66c4"
-      app.config.session_store :cookie_store, key: "_myapp_session"
-      app.config.active_support.deprecation = :log
-      app.config.active_support.test_order = :random
-      app.config.log_level = :info
+      @app = Class.new(Rails::Application)
+      @app.config.eager_load = false
+      @app.secrets.secret_key_base = "3b7cd727ee24e8444053437c36cc66c4"
+      @app.config.session_store :cookie_store, key: "_myapp_session"
+      @app.config.active_support.deprecation = :log
+      @app.config.active_support.test_order = :random
+      @app.config.log_level = :info
 
-      yield app if block_given?
-      app.initialize!
+      yield @app if block_given?
+      @app.initialize!
 
-      app.routes.draw do
+      @app.routes.draw do
         get "/" => "omg#index"
       end
 
@@ -268,19 +276,13 @@ module TestHelpers
       File.open(file, "w+") { |f| f.puts contents }
     end
 
-    def app_file(path, contents)
+    def app_file(path, contents, mode = 'w')
       FileUtils.mkdir_p File.dirname("#{app_path}/#{path}")
-      File.open("#{app_path}/#{path}", 'w') do |f|
+      File.open("#{app_path}/#{path}", mode) do |f|
         f.puts contents
       end
     end
 
-    def gsub_app_file(path, regexp, *args, &block)
-      path = "#{app_path}/#{path}"
-      content = File.read(path).gsub(regexp, *args, &block)
-      File.open(path, 'wb') { |f| f.write(content) }
-    end
-
     def remove_file(path)
       FileUtils.rm_rf "#{app_path}/#{path}"
     end
@@ -300,7 +302,10 @@ module TestHelpers
     end
 
     def boot_rails
-      require File.expand_path('../../../../load_paths', __FILE__)
+      # FIXME: shush Sass warning spam, not relevant to testing Railties
+      Kernel.silence_warnings do
+        require File.expand_path('../../../../load_paths', __FILE__)
+      end
     end
   end
 end
@@ -309,45 +314,10 @@ class ActiveSupport::TestCase
   include TestHelpers::Paths
   include TestHelpers::Rack
   include TestHelpers::Generation
+  include ActiveSupport::Testing::Stream
 
   self.test_order = :sorted
 
-  private
-
-  def capture(stream)
-    stream = stream.to_s
-    captured_stream = Tempfile.new(stream)
-    stream_io = eval("$#{stream}")
-    origin_stream = stream_io.dup
-    stream_io.reopen(captured_stream)
-
-    yield
-
-    stream_io.rewind
-    return captured_stream.read
-  ensure
-    captured_stream.close
-    captured_stream.unlink
-    stream_io.reopen(origin_stream)
-  end
-
-  def quietly
-    silence_stream(STDOUT) do
-      silence_stream(STDERR) do
-        yield
-      end
-    end
-  end
-
-  def silence_stream(stream)
-    old_stream = stream.dup
-    stream.reopen(IO::NULL)
-    stream.sync = true
-    yield
-  ensure
-    stream.reopen(old_stream)
-    old_stream.close
-  end
 end
 
 # Create a scope and build a fixture rails app
@@ -361,7 +331,7 @@ Module.new do
   environment = File.expand_path('../../../../load_paths', __FILE__)
   require_environment = "-r #{environment}"
 
-  `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/bin/rails new #{app_template_path} --skip-gemfile --no-rc`
+  `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/exe/rails new #{app_template_path} --skip-gemfile --no-rc`
   File.open("#{app_template_path}/config/boot.rb", 'w') do |f|
     f.puts "require '#{environment}'"
     f.puts "require 'rails/all'"
diff --git a/railties/test/path_generation_test.rb b/railties/test/path_generation_test.rb
index 13bf29d3c3..a16adc72a6 100644
--- a/railties/test/path_generation_test.rb
+++ b/railties/test/path_generation_test.rb
@@ -1,41 +1,36 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'active_support/core_ext/object/with_options'
 require 'active_support/core_ext/object/json'
-require 'rails'
-require 'rails/application'
-
-ROUTING = ActionDispatch::Routing
 
 class PathGenerationTest < ActiveSupport::TestCase
   attr_reader :app
 
-  class TestSet < ROUTING::RouteSet
+  class TestSet < ActionDispatch::Routing::RouteSet
     def initialize(block)
       @block = block
       super()
     end
 
-    class Dispatcher < ROUTING::RouteSet::Dispatcher
-      def initialize(defaults, set, block)
-        super(defaults)
+    class Request < DelegateClass(ActionDispatch::Request)
+      def initialize(target, url_helpers, block)
+        super(target)
+        @url_helpers = url_helpers
         @block = block
-        @set = set
       end
 
-      def controller_reference(controller_param)
+      def controller_class
+        url_helpers = @url_helpers
         block = @block
-        set = @set
         Class.new(ActionController::Base) {
-          include set.url_helpers
+          include url_helpers
           define_method(:process) { |name| block.call(self) }
           def to_a; [200, {}, []]; end
         }
       end
     end
 
-    def dispatcher defaults
-      TestSet::Dispatcher.new defaults, self, @block
+    def make_request(env)
+      Request.new super, self.url_helpers, @block
     end
   end
 
diff --git a/railties/test/paths_test.rb b/railties/test/paths_test.rb
index 1aeb9ec339..96b54c7264 100644
--- a/railties/test/paths_test.rb
+++ b/railties/test/paths_test.rb
@@ -1,10 +1,9 @@
 require 'abstract_unit'
 require 'rails/paths'
-require 'mocha/setup' # FIXME: stop using mocha
+require 'minitest/mock'
 
 class PathsTest < ActiveSupport::TestCase
   def setup
-    File.stubs(:exist?).returns(true)
     @root = Rails::Paths::Root.new("/foo/bar")
   end
 
@@ -63,6 +62,13 @@ class PathsTest < ActiveSupport::TestCase
     assert_equal ["/foo/bar/baz"], @root["app/models"].to_a
   end
 
+  test "absolute current path" do
+    @root.add "config"
+    @root.add "config/locales"
+
+    assert_equal "/foo/bar/config/locales", @root["config/locales"].absolute_current
+  end
+
   test "adding multiple physical paths as an array" do
     @root.add "app", with: ["/app", "/app2"]
     assert_equal ["/app", "/app2"], @root["app"].to_a
@@ -93,10 +99,12 @@ class PathsTest < ActiveSupport::TestCase
   end
 
   test "it is possible to add a path that should be autoloaded only once" do
-    @root.add "app", with: "/app"
-    @root["app"].autoload_once!
-    assert @root["app"].autoload_once?
-    assert @root.autoload_once.include?(@root["app"].expanded.first)
+    File.stub(:exist?, true) do
+      @root.add "app", with: "/app"
+      @root["app"].autoload_once!
+      assert @root["app"].autoload_once?
+      assert @root.autoload_once.include?(@root["app"].expanded.first)
+    end
   end
 
   test "it is possible to remove a path that should be autoloaded only once" do
@@ -110,37 +118,47 @@ class PathsTest < ActiveSupport::TestCase
   end
 
   test "it is possible to add a path without assignment and specify it should be loaded only once" do
-    @root.add "app", with: "/app", autoload_once: true
-    assert @root["app"].autoload_once?
-    assert @root.autoload_once.include?("/app")
+    File.stub(:exist?, true) do
+      @root.add "app", with: "/app", autoload_once: true
+      assert @root["app"].autoload_once?
+      assert @root.autoload_once.include?("/app")
+    end
   end
 
   test "it is possible to add multiple paths without assignment and specify it should be loaded only once" do
-    @root.add "app", with: ["/app", "/app2"], autoload_once: true
-    assert @root["app"].autoload_once?
-    assert @root.autoload_once.include?("/app")
-    assert @root.autoload_once.include?("/app2")
+    File.stub(:exist?, true) do
+      @root.add "app", with: ["/app", "/app2"], autoload_once: true
+      assert @root["app"].autoload_once?
+      assert @root.autoload_once.include?("/app")
+      assert @root.autoload_once.include?("/app2")
+    end
   end
 
   test "making a path autoload_once more than once only includes it once in @root.load_once" do
-    @root["app"] = "/app"
-    @root["app"].autoload_once!
-    @root["app"].autoload_once!
-    assert_equal 1, @root.autoload_once.select {|p| p == @root["app"].expanded.first }.size
+    File.stub(:exist?, true) do
+      @root["app"] = "/app"
+      @root["app"].autoload_once!
+      @root["app"].autoload_once!
+      assert_equal 1, @root.autoload_once.select {|p| p == @root["app"].expanded.first }.size
+    end
   end
 
   test "paths added to a load_once path should be added to the autoload_once collection" do
-    @root["app"] = "/app"
-    @root["app"].autoload_once!
-    @root["app"] << "/app2"
-    assert_equal 2, @root.autoload_once.size
+    File.stub(:exist?, true) do
+      @root["app"] = "/app"
+      @root["app"].autoload_once!
+      @root["app"] << "/app2"
+      assert_equal 2, @root.autoload_once.size
+    end
   end
 
   test "it is possible to mark a path as eager loaded" do
-    @root["app"] = "/app"
-    @root["app"].eager_load!
-    assert @root["app"].eager_load?
-    assert @root.eager_load.include?(@root["app"].to_a.first)
+    File.stub(:exist?, true) do
+      @root["app"] = "/app"
+      @root["app"].eager_load!
+      assert @root["app"].eager_load?
+      assert @root.eager_load.include?(@root["app"].to_a.first)
+    end
   end
 
   test "it is possible to skip a path from eager loading" do
@@ -154,38 +172,48 @@ class PathsTest < ActiveSupport::TestCase
   end
 
   test "it is possible to add a path without assignment and mark it as eager" do
-    @root.add "app", with: "/app", eager_load: true
-    assert @root["app"].eager_load?
-    assert @root.eager_load.include?("/app")
+    File.stub(:exist?, true) do
+      @root.add "app", with: "/app", eager_load: true
+      assert @root["app"].eager_load?
+      assert @root.eager_load.include?("/app")
+    end
   end
 
   test "it is possible to add multiple paths without assignment and mark them as eager" do
-    @root.add "app", with: ["/app", "/app2"], eager_load: true
-    assert @root["app"].eager_load?
-    assert @root.eager_load.include?("/app")
-    assert @root.eager_load.include?("/app2")
+    File.stub(:exist?, true) do
+      @root.add "app", with: ["/app", "/app2"], eager_load: true
+      assert @root["app"].eager_load?
+      assert @root.eager_load.include?("/app")
+      assert @root.eager_load.include?("/app2")
+    end
   end
 
   test "it is possible to create a path without assignment and mark it both as eager and load once" do
-    @root.add "app", with: "/app", eager_load: true, autoload_once: true
-    assert @root["app"].eager_load?
-    assert @root["app"].autoload_once?
-    assert @root.eager_load.include?("/app")
-    assert @root.autoload_once.include?("/app")
+    File.stub(:exist?, true) do
+      @root.add "app", with: "/app", eager_load: true, autoload_once: true
+      assert @root["app"].eager_load?
+      assert @root["app"].autoload_once?
+      assert @root.eager_load.include?("/app")
+      assert @root.autoload_once.include?("/app")
+    end
   end
 
   test "making a path eager more than once only includes it once in @root.eager_paths" do
-    @root["app"] = "/app"
-    @root["app"].eager_load!
-    @root["app"].eager_load!
-    assert_equal 1, @root.eager_load.select {|p| p == @root["app"].expanded.first }.size
+    File.stub(:exist?, true) do
+      @root["app"] = "/app"
+      @root["app"].eager_load!
+      @root["app"].eager_load!
+      assert_equal 1, @root.eager_load.select {|p| p == @root["app"].expanded.first }.size
+    end
   end
 
   test "paths added to an eager_load path should be added to the eager_load collection" do
-    @root["app"] = "/app"
-    @root["app"].eager_load!
-    @root["app"] << "/app2"
-    assert_equal 2, @root.eager_load.size
+    File.stub(:exist?, true) do
+      @root["app"] = "/app"
+      @root["app"].eager_load!
+      @root["app"] << "/app2"
+      assert_equal 2, @root.eager_load.size
+    end
   end
 
   test "it should be possible to add a path's default glob" do
@@ -194,6 +222,12 @@ class PathsTest < ActiveSupport::TestCase
     assert_equal "*.rb", @root["app"].glob
   end
 
+  test "it should be possible to get extensions by glob" do
+    @root["app"] = "/app"
+    @root["app"].glob = "*.{rb,yml}"
+    assert_equal ["rb", "yml"], @root["app"].extensions
+  end
+
   test "it should be possible to override a path's default glob without assignment" do
     @root.add "app", with: "/app", glob: "*.rb"
     assert_equal "*.rb", @root["app"].glob
@@ -207,28 +241,36 @@ class PathsTest < ActiveSupport::TestCase
   end
 
   test "a path can be added to the load path" do
-    @root["app"] = "app"
-    @root["app"].load_path!
-    @root["app/models"] = "app/models"
-    assert_equal ["/foo/bar/app"], @root.load_paths
+    File.stub(:exist?, true) do
+      @root["app"] = "app"
+      @root["app"].load_path!
+      @root["app/models"] = "app/models"
+      assert_equal ["/foo/bar/app"], @root.load_paths
+    end
   end
 
   test "a path can be added to the load path on creation" do
-    @root.add "app", with: "/app", load_path: true
-    assert @root["app"].load_path?
-    assert_equal ["/app"], @root.load_paths
+    File.stub(:exist?, true) do
+      @root.add "app", with: "/app", load_path: true
+      assert @root["app"].load_path?
+      assert_equal ["/app"], @root.load_paths
+    end
   end
 
   test "a path can be marked as autoload path" do
-    @root["app"] = "app"
-    @root["app"].autoload!
-    @root["app/models"] = "app/models"
-    assert_equal ["/foo/bar/app"], @root.autoload_paths
+    File.stub(:exist?, true) do
+      @root["app"] = "app"
+      @root["app"].autoload!
+      @root["app/models"] = "app/models"
+      assert_equal ["/foo/bar/app"], @root.autoload_paths
+    end
   end
 
   test "a path can be marked as autoload on creation" do
-    @root.add "app", with: "/app", autoload: true
-    assert @root["app"].autoload?
-    assert_equal ["/app"], @root.autoload_paths
+    File.stub(:exist?, true) do
+      @root.add "app", with: "/app", autoload: true
+      assert @root["app"].autoload?
+      assert_equal ["/app"], @root.autoload_paths
+    end
   end
 end
diff --git a/railties/test/rails_info_controller_test.rb b/railties/test/rails_info_controller_test.rb
index d336a2e6c0..c51503c2b7 100644
--- a/railties/test/rails_info_controller_test.rb
+++ b/railties/test/rails_info_controller_test.rb
@@ -16,7 +16,7 @@ class InfoControllerTest < ActionController::TestCase
     end
     @routes = Rails.application.routes
 
-    Rails::InfoController.send(:include, @routes.url_helpers)
+    Rails::InfoController.include(@routes.url_helpers)
 
     @request.env["REMOTE_ADDR"] = "127.0.0.1"
   end
@@ -53,4 +53,29 @@ class InfoControllerTest < ActionController::TestCase
     assert_response :success
   end
 
+  test "info controller returns exact matches" do
+    exact_count = -> { JSON(response.body)['exact'].size }
+
+    get :routes, params: { path: 'rails/info/route' }
+    assert exact_count.call == 0, 'should not match incomplete routes'
+
+    get :routes, params: { path: 'rails/info/routes' }
+    assert exact_count.call == 1, 'should match complete routes'
+
+    get :routes, params: { path: 'rails/info/routes.html' }
+    assert exact_count.call == 1, 'should match complete routes with optional parts'
+  end
+
+  test "info controller returns fuzzy matches" do
+    fuzzy_count = -> { JSON(response.body)['fuzzy'].size }
+
+    get :routes, params: { path: 'rails/info' }
+    assert fuzzy_count.call == 2, 'should match incomplete routes'
+
+    get :routes, params: { path: 'rails/info/routes' }
+    assert fuzzy_count.call == 1, 'should match complete routes'
+
+    get :routes, params: { path: 'rails/info/routes.html' }
+    assert fuzzy_count.call == 0, 'should match optional parts of route literally'
+  end
 end
diff --git a/railties/test/railties/engine_test.rb b/railties/test/railties/engine_test.rb
index 6185742cc1..2c82f728ee 100644
--- a/railties/test/railties/engine_test.rb
+++ b/railties/test/railties/engine_test.rb
@@ -1155,10 +1155,10 @@ YAML
       assert_equal "App's bar partial", last_response.body.strip
 
       get("/assets/foo.js")
-      assert_equal "// Bukkit's foo js\n;", last_response.body.strip
+      assert_equal "// Bukkit's foo js", last_response.body.strip
 
       get("/assets/bar.js")
-      assert_equal "// App's bar js\n;", last_response.body.strip
+      assert_equal "// App's bar js", last_response.body.strip
 
       # ensure that railties are not added twice
       railties = Rails.application.send(:ordered_railties).map(&:class)
@@ -1304,6 +1304,55 @@ YAML
       assert_equal '/foo/bukkits/bukkit', last_response.body
     end
 
+    test "paths are properly generated when application is mounted at sub-path and relative_url_root is set" do
+      add_to_config "config.relative_url_root = '/foo'"
+
+      @plugin.write "lib/bukkits.rb", <<-RUBY
+        module Bukkits
+          class Engine < ::Rails::Engine
+            isolate_namespace Bukkits
+          end
+        end
+      RUBY
+
+      app_file "app/controllers/bar_controller.rb", <<-RUBY
+        class BarController < ApplicationController
+          def index
+            render text: bukkits.bukkit_path
+          end
+        end
+      RUBY
+
+      app_file "config/routes.rb", <<-RUBY
+        Rails.application.routes.draw do
+          get '/bar' => 'bar#index', :as => 'bar'
+          mount Bukkits::Engine => "/bukkits", :as => "bukkits"
+        end
+      RUBY
+
+      @plugin.write "config/routes.rb", <<-RUBY
+        Bukkits::Engine.routes.draw do
+          get '/bukkit' => 'bukkit#index'
+        end
+      RUBY
+
+      @plugin.write "app/controllers/bukkits/bukkit_controller.rb", <<-RUBY
+        class Bukkits::BukkitController < ActionController::Base
+          def index
+            render text: main_app.bar_path
+          end
+        end
+      RUBY
+
+      boot_rails
+
+      get("/bukkits/bukkit", {}, {'SCRIPT_NAME' => '/foo'})
+      assert_equal '/foo/bar', last_response.body
+
+      get("/bar", {}, {'SCRIPT_NAME' => '/foo'})
+      assert_equal '/foo/bukkits/bukkit', last_response.body
+    end
+
   private
     def app
       Rails.application
diff --git a/railties/test/railties/generators_test.rb b/railties/test/railties/generators_test.rb
index 7348d70c56..5f4171d44b 100644
--- a/railties/test/railties/generators_test.rb
+++ b/railties/test/railties/generators_test.rb
@@ -30,7 +30,7 @@ module RailtiesTests
       if File.exist?("#{environment}.rb")
         require_environment = "-r #{environment}"
       end
-      `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/bin/rails #{cmd}`
+      `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/exe/rails #{cmd}`
     end
 
     def build_engine(is_mountable=false)
@@ -122,5 +122,13 @@ module RailtiesTests
         assert_no_file "app/helpers/foo_bar/topics_helper.rb"
       end
     end
+
+    def test_assert_file_with_special_characters
+      path = "#{app_path}/tmp"
+      file_name = "#{path}/v0.1.4~alpha+nightly"
+      FileUtils.mkdir_p path
+      FileUtils.touch file_name
+      assert_file file_name
+    end
   end
 end
diff --git a/railties/test/test_info_test.rb b/railties/test/test_info_test.rb
deleted file mode 100644
index b9c3a9c0c7..0000000000
--- a/railties/test/test_info_test.rb
+++ /dev/null
@@ -1,60 +0,0 @@
-require 'abstract_unit'
-require 'rails/test_unit/sub_test_task'
-
-module Rails
-  class TestInfoTest < ActiveSupport::TestCase
-    def test_test_files
-      info = new_test_info ['test']
-      assert_predicate info.files, :empty?
-      assert_nil info.opts
-      assert_equal ['test'], info.tasks
-    end
-
-    def test_with_file
-      info = new_test_info ['test', __FILE__]
-      assert_equal [__FILE__], info.files
-      assert_nil info.opts
-      assert_equal ['test'], info.tasks
-    end
-
-    def test_with_opts
-      info = new_test_info ['test', __FILE__, '/foo/']
-      assert_equal [__FILE__], info.files
-      assert_equal '-n /foo/', info.opts
-      assert_equal ['test'], info.tasks
-    end
-
-    def test_with_model_shorthand
-      info = new_test_info ['test', 'models/foo', '/foo/']
-
-      def info.test_file?(file)
-        file == "test/models/foo_test.rb" || super
-      end
-
-      assert_equal ['test/models/foo_test.rb'], info.files
-      assert_equal '-n /foo/', info.opts
-      assert_equal ['test'], info.tasks
-    end
-
-    def test_with_model_path
-      info = new_test_info ['test', 'app/models/foo.rb', '/foo/']
-
-      def info.test_file?(file)
-        file == "test/models/foo_test.rb" || super
-      end
-
-      assert_equal ['test/models/foo_test.rb'], info.files
-      assert_equal '-n /foo/', info.opts
-      assert_equal ['test'], info.tasks
-    end
-
-    private
-    def new_test_info(tasks)
-      Class.new(TestTask::TestInfo) {
-        def task_defined?(task)
-          task == "test"
-        end
-      }.new tasks
-    end
-  end
-end
diff --git a/railties/test/test_unit/reporter_test.rb b/railties/test/test_unit/reporter_test.rb
new file mode 100644
index 0000000000..fa6bb71c64
--- /dev/null
+++ b/railties/test/test_unit/reporter_test.rb
@@ -0,0 +1,147 @@
+require 'abstract_unit'
+require 'rails/test_unit/reporter'
+
+class TestUnitReporterTest < ActiveSupport::TestCase
+  class ExampleTest < Minitest::Test
+    def woot; end
+  end
+
+  setup do
+    @output = StringIO.new
+    @reporter = Rails::TestUnitReporter.new @output, output_inline: true
+  end
+
+  test "prints rerun snippet to run a single failed test" do
+    @reporter.record(failed_test)
+    @reporter.report
+
+    assert_match %r{^bin/rails test .*test/test_unit/reporter_test.rb:6$}, @output.string
+    assert_rerun_snippet_count 1
+  end
+
+  test "prints rerun snippet for every failed test" do
+    @reporter.record(failed_test)
+    @reporter.record(failed_test)
+    @reporter.record(failed_test)
+    @reporter.report
+
+    assert_rerun_snippet_count 3
+  end
+
+  test "does not print snippet for successful and skipped tests" do
+    @reporter.record(passing_test)
+    @reporter.record(skipped_test)
+    @reporter.report
+    assert_no_match 'Failed tests:', @output.string
+    assert_rerun_snippet_count 0
+  end
+
+  test "prints rerun snippet for skipped tests if run in verbose mode" do
+    verbose = Rails::TestUnitReporter.new @output, verbose: true
+    verbose.record(skipped_test)
+    verbose.report
+
+    assert_rerun_snippet_count 1
+  end
+
+  test "allows to customize the executable in the rerun snippet" do
+    original_executable = Rails::TestUnitReporter.executable
+    begin
+      Rails::TestUnitReporter.executable = "bin/test"
+      @reporter.record(failed_test)
+      @reporter.report
+
+      assert_match %r{^bin/test .*test/test_unit/reporter_test.rb:6$}, @output.string
+    ensure
+      Rails::TestUnitReporter.executable = original_executable
+    end
+  end
+
+  test "outputs failures inline" do
+    @reporter.record(failed_test)
+    @reporter.report
+
+    assert_match %r{\A\n\nboo\n\nbin/rails test .*test/test_unit/reporter_test.rb:6\n\n\z}, @output.string
+  end
+
+  test "outputs errors inline" do
+    @reporter.record(errored_test)
+    @reporter.report
+
+    assert_match %r{\A\n\nArgumentError: wups\n    No backtrace\n\nbin/rails test .*test/test_unit/reporter_test.rb:6\n\n\z}, @output.string
+  end
+
+  test "outputs skipped tests inline if verbose" do
+    verbose = Rails::TestUnitReporter.new @output, verbose: true, output_inline: true
+    verbose.record(skipped_test)
+    verbose.report
+
+    assert_match %r{\A\n\nskipchurches, misstemples\n\nbin/rails test .*test/test_unit/reporter_test.rb:6\n\n\z}, @output.string
+  end
+
+  test "does not output rerun snippets after run" do
+    @reporter.record(failed_test)
+    @reporter.report
+
+    assert_no_match 'Failed tests:', @output.string
+  end
+
+  test "fail fast interrupts run on failure" do
+    fail_fast = Rails::TestUnitReporter.new @output, fail_fast: true
+    interrupt_raised = false
+
+    # Minitest passes through Interrupt, catch it manually.
+    begin
+      fail_fast.record(failed_test)
+    rescue Interrupt
+      interrupt_raised = true
+    ensure
+      assert interrupt_raised, 'Expected Interrupt to be raised.'
+    end
+  end
+
+  test "fail fast does not interrupt run errors or skips" do
+    fail_fast = Rails::TestUnitReporter.new @output, fail_fast: true
+
+    fail_fast.record(errored_test)
+    assert_no_match 'Failed tests:', @output.string
+
+    fail_fast.record(skipped_test)
+    assert_no_match 'Failed tests:', @output.string
+  end
+
+  private
+  def assert_rerun_snippet_count(snippet_count)
+    assert_equal snippet_count, @output.string.scan(%r{^bin/rails test }).size
+  end
+
+  def failed_test
+    ft = ExampleTest.new(:woot)
+    ft.failures << begin
+                     raise Minitest::Assertion, "boo"
+                   rescue Minitest::Assertion => e
+                     e
+                   end
+    ft
+  end
+
+  def errored_test
+    et = ExampleTest.new(:woot)
+    et.failures << Minitest::UnexpectedError.new(ArgumentError.new("wups"))
+    et
+  end
+
+  def passing_test
+    ExampleTest.new(:woot)
+  end
+
+  def skipped_test
+    st = ExampleTest.new(:woot)
+    st.failures << begin
+                     raise Minitest::Skip, "skipchurches, misstemples"
+                   rescue Minitest::Assertion => e
+                     e
+                   end
+    st
+  end
+end
diff --git a/tasks/release.rb b/tasks/release.rb
index d8c1390eef..2c7e927679 100644
--- a/tasks/release.rb
+++ b/tasks/release.rb
@@ -98,7 +98,7 @@ namespace :all do
   task :push            => FRAMEWORKS.map { |f| "#{f}:push"            } + ['rails:push']
 
   task :ensure_clean_state do
-    unless `git status -s | grep -v RAILS_VERSION`.strip.empty?
+    unless `git status -s | grep -v 'RAILS_VERSION\\|CHANGELOG'`.strip.empty?
       abort "[ABORTING] `git status` reports a dirty tree. Make sure all changes are committed"
     end
 
diff --git a/tools/line_statistics b/tools/line_statistics
index bfa921b095..d0b3557d7d 100644
--- a/tools/line_statistics
+++ b/tools/line_statistics
@@ -1,4 +1,4 @@
-# Class used to calculates LOC for a provided file list.
+# Class used to calculate LOC for a provided file list.
 #
 # Example:
 #   files = FileList["lib/active_record/**/*.rb"]
diff --git a/tools/profile b/tools/profile
index eb7fc7792b..191e73b3dd 100755
--- a/tools/profile
+++ b/tools/profile
@@ -117,9 +117,9 @@ rescue LoadError
     def camelize(uppercase_first_letter = true)
       string = self
       if uppercase_first_letter
-        string = string.sub(/^[a-z\d]*/) { $&.capitalize }
+        string = string.sub(/^[a-z\d]*/) { |match| match.capitalize }
       else
-        string = string.sub(/^(?:(?=\b|[A-Z_])|\w)/) { $&.downcase }
+        string = string.sub(/^(?:(?=\b|[A-Z_])|\w)/) { |match| match.downcase }
       end
       string.gsub(/(?:_|(\/))([a-z\d]*)/) { "#{$1}#{$2.capitalize}" }.gsub('/', '::')
     end
diff --git a/tools/test.rb b/tools/test.rb
new file mode 100644
index 0000000000..70f295b554
--- /dev/null
+++ b/tools/test.rb
@@ -0,0 +1,12 @@
+$: << File.expand_path("test", COMPONENT_ROOT)
+require File.expand_path("../../load_paths", __FILE__)
+require "rails/test_unit/minitest_plugin"
+
+module Rails
+  # Necessary to get rerun-snippts working.
+  def self.root
+    @root ||= Pathname.new(COMPONENT_ROOT)
+  end
+end
+
+Rails::TestUnitReporter.executable = "bin/test"