Merge branch 'master' into laurocaetano-fix_send_file

* master: (536 commits)
  doc, API example on how to use `Model#exists?` with multiple IDs. [ci skip]
  Restore DATABASE_URL even if it's nil in connection_handler test
  [ci skip] - error_messages_for has been deprecated since 2.3.8 - lets reduce any confusion for users
  Ensure Active Record connection consistency
  Revert "ask the fixture set for the sql statements"
  Check `respond_to` before delegation due to: https://github.com/ruby/ruby/commit/d781caaf313b8649948c107bba277e5ad7307314
  Adding Hash#compact and Hash#compact! methods
  MySQL version 4.1 was EOL on December 31, 2009 We should at least recommend modern versions of MySQL to users.
  clear cache on body close so that cache remains during rendering
  add a more restricted codepath for templates fixes #13390
  refactor generator tests to use block form of Tempfile
  Fix typo [ci skip]
  Move finish_template as the last public method in the generator
  Minor typos fix [ci skip]
  make `change_column_null` reversible. Closes #13576.
  create/drop test and development databases only if RAILS_ENV is nil
  Revert "Speedup String#to"
  typo fix in test name. [ci skip].
  `core_ext/string/access.rb` test what we are documenting.
  Fix typo in image_tag documentation
  ...

Conflicts:
	actionpack/CHANGELOG.md

73 files changed, 1523 insertions, 244 deletions

diff --git a/railties/CHANGELOG.md b/railties/CHANGELOG.md
index 21ac596ab9..21887c32fe 100644
--- a/railties/CHANGELOG.md
+++ b/railties/CHANGELOG.md
@@ -1,3 +1,88 @@
+*   `test_help.rb` now automatically checks/maintains your test datbase
+    schema. (Use `config.active_record.maintain_test_schema = false` to
+    disable.)
+
+    *Jon Leighton*
+
+*   Configure `secrets.yml` and `database.yml` to read configuration
+    from the system environment by default for production.
+
+    *José Valim*
+
+*   `config.assets.raise_runtime_errors` is set to true by default
+
+    This option has been introduced in
+    [sprockets-rails#100][https://github.com/rails/sprockets-rails/pull/100]
+    and defaults to true in new applications in development.
+
+    *Richard Schneeman*
+
+*   Generates `html` and `text` templates for mailers by default.
+
+    *Kassio Borges*
+
+*   Move `secret_key_base` from `config/initializers/secret_token.rb`
+    to `config/secrets.yml`.
+
+    `secret_key_base` is now saved in `Rails.application.secrets.secret_key_base`
+    and it fallbacks to the value of `config.secret_key_base` when it is not
+    present in `config/secrets.yml`.
+
+    `config/initializers/secret_token.rb` is not generated by default
+    in new applications.
+
+    *Guillermo Iguaran*
+
+*   Generate a new `secrets.yml` file in the `config` folder for new
+    applications. 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 will be accessible via `Rails.application.secrets`.
+    For example, with the following `secrets.yml`:
+
+        development:
+          secret_key_base: 3b7cd727ee24e8444053437c36cc66c3
+          some_api_key: SOMEKEY
+
+    `Rails.application.secrets.some_api_key` will return `SOMEKEY` in the development
+    environment.
+
+    *Guillermo Iguaran*
+
+*   Add `ENV['DATABASE_URL']` support in `rails dbconsole`. Fixes #13320.
+
+    *Huiming Teo*
+
+*   Add `Application#message_verifier` method to return a message verifier.
+
+    This verifier can be used to generate and verify signed messages in the application.
+
+        message = Rails.application.message_verifier(:sensitive_data).generate('my sensible data')
+        Rails.application.message_verifier(:sensitive_data).verify(message)
+        # => 'my sensible data'
+
+    It is recommended not to use the same verifier for different things, so you can get different
+    verifiers passing the name argument.
+
+        message = Rails.application.message_verifier(:cookies).generate('my sensible cookie data')
+
+    See the `ActiveSupport::MessageVerifier` documentation for more information.
+
+    *Rafael Mendonça França*
+
+*   The [Spring application
+    preloader](https://github.com/jonleighton/spring) is now installed
+    by default for new applications. It uses the development group of
+    the Gemfile, so will not be installed in production.
+
+    *Jon Leighton*
+
+*   Uses .railsrc while creating new plugin if it is available.
+    Fixes #10700.
+
+    *Prathamesh Sonpatki*
+
 *   Remove turbolinks when generating a new application based on a template that skips it.
 
     Example:
@@ -148,11 +233,11 @@
     *Paul Nikitochkin*
 
 *   Remove deprecated `ActiveRecord::Generators::ActiveModel#update_attributes` in
-    favor of `ActiveRecord::Generators::ActiveModel#update`
+    favor of `ActiveRecord::Generators::ActiveModel#update`.
 
     *Vipul A M*
 
-*   Remove deprecated `config.whiny_nils` option
+*   Remove deprecated `config.whiny_nils` option.
 
     *Vipul A M*
 
diff --git a/railties/MIT-LICENSE b/railties/MIT-LICENSE
index 0d7fb865e2..2950f05b11 100644
--- a/railties/MIT-LICENSE
+++ b/railties/MIT-LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2004-2013 David Heinemeier Hansson
+Copyright (c) 2004-2014 David Heinemeier Hansson
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
diff --git a/railties/lib/rails.rb b/railties/lib/rails.rb
index ea82327365..be7570a5ba 100644
--- a/railties/lib/rails.rb
+++ b/railties/lib/rails.rb
@@ -25,6 +25,7 @@ module Rails
 
   autoload :Info
   autoload :InfoController
+  autoload :MailersController
   autoload :WelcomeController
 
   class << self
diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index d1e88cfafd..05acd78d98 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -1,6 +1,8 @@
 require 'fileutils'
+require 'active_support/core_ext/hash/keys'
 require 'active_support/core_ext/object/blank'
 require 'active_support/key_generator'
+require 'active_support/message_verifier'
 require 'rails/engine'
 
 module Rails
@@ -103,16 +105,17 @@ module Rails
     delegate :default_url_options, :default_url_options=, to: :routes
 
     INITIAL_VARIABLES = [:config, :railties, :routes_reloader, :reloaders,
-                         :routes, :helpers, :app_env_config] # :nodoc:
+                         :routes, :helpers, :app_env_config, :secrets] # :nodoc:
 
     def initialize(initial_variable_values = {}, &block)
       super()
-      @initialized      = false
-      @reloaders        = []
-      @routes_reloader  = nil
-      @app_env_config   = nil
-      @ordered_railties = nil
-      @railties         = nil
+      @initialized       = false
+      @reloaders         = []
+      @routes_reloader   = nil
+      @app_env_config    = nil
+      @ordered_railties  = nil
+      @railties          = nil
+      @message_verifiers = {}
 
       add_lib_to_load_path!
       ActiveSupport.run_load_hooks(:before_configuration, self)
@@ -149,8 +152,8 @@ module Rails
       # 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 ||= begin
-        if config.secret_key_base
-          key_generator = ActiveSupport::KeyGenerator.new(config.secret_key_base, iterations: 1000)
+        if secrets.secret_key_base
+          key_generator = ActiveSupport::KeyGenerator.new(secrets.secret_key_base, iterations: 1000)
           ActiveSupport::CachingKeyGenerator.new(key_generator)
         else
           ActiveSupport::LegacyKeyGenerator.new(config.secret_token)
@@ -158,6 +161,31 @@ module Rails
       end
     end
 
+    # Returns a message verifier object.
+    #
+    # This verifier can be used to generate and verify signed messages in the application.
+    #
+    # It is recommended not to use the same verifier for different things, so you can get different
+    # verifiers passing the +verifier_name+ argument.
+    #
+    # ==== Parameters
+    #
+    # * +verifier_name+ - the name of the message verifier.
+    #
+    # ==== Examples
+    #
+    #     message = Rails.application.message_verifier('sensitive_data').generate('my sensible data')
+    #     Rails.application.message_verifier('sensitive_data').verify(message)
+    #     # => 'my sensible data'
+    #
+    # See the +ActiveSupport::MessageVerifier+ documentation for more information.
+    def message_verifier(verifier_name)
+      @message_verifiers[verifier_name] ||= begin
+        secret = key_generator.generate_key(verifier_name.to_s)
+        ActiveSupport::MessageVerifier.new(secret)
+      end
+    end
+
     # Stores some of the Rails initial environment parameters which
     # will be used by middlewares and engines to configure themselves.
     def env_config
@@ -168,7 +196,7 @@ module Rails
           "action_dispatch.parameter_filter" => config.filter_parameters,
           "action_dispatch.redirect_filter" => config.filter_redirect,
           "action_dispatch.secret_token" => config.secret_token,
-          "action_dispatch.secret_key_base" => config.secret_key_base,
+          "action_dispatch.secret_key_base" => secrets.secret_key_base,
           "action_dispatch.show_exceptions" => config.action_dispatch.show_exceptions,
           "action_dispatch.show_detailed_exceptions" => config.consider_all_requests_local,
           "action_dispatch.logger" => Rails.logger,
@@ -273,6 +301,27 @@ module Rails
       @config = configuration
     end
 
+    def secrets #:nodoc:
+      @secrets ||= begin
+        secrets = ActiveSupport::OrderedOptions.new
+        yaml = config.paths["config/secrets"].first
+        if File.exist?(yaml)
+          require "erb"
+          env_secrets = YAML.load(ERB.new(IO.read(yaml)).result)[Rails.env]
+          secrets.merge!(env_secrets.symbolize_keys) if env_secrets
+        end
+
+        # Fallback to config.secret_key_base if secrets.secret_key_base isn't set
+        secrets.secret_key_base ||= config.secret_key_base
+
+        secrets
+      end
+    end
+
+    def secrets=(secrets) #:nodoc:
+      @secrets = secrets
+    end
+
     def to_app #:nodoc:
       self
     end
@@ -364,8 +413,8 @@ module Rails
     end
 
     def validate_secret_key_config! #:nodoc:
-      if config.secret_key_base.blank? && config.secret_token.blank?
-        raise "You must set config.secret_key_base in your app's config."
+      if secrets.secret_key_base.blank? && config.secret_token.blank?
+        raise "Missing `secret_key_base` for '#{Rails.env}' environment, set this value in `config/secrets.yml`"
       end
     end
   end
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index dd0b9c6d70..e902205a13 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -76,6 +76,7 @@ module Rails
         @paths ||= begin
           paths = super
           paths.add "config/database",    with: "config/database.yml"
+          paths.add "config/secrets",     with: "config/secrets.yml"
           paths.add "config/environment", with: "config/environment.rb"
           paths.add "lib/templates"
           paths.add "log",                with: "log/#{Rails.env}.log"
@@ -87,17 +88,23 @@ module Rails
         end
       end
 
-      # Loads and returns the configuration of the database.
+      # Loads and returns the entire raw configuration of database from
+      # values stored in `config/database.yml`.
       def database_configuration
-        yaml = paths["config/database"].first
-        if File.exist?(yaml)
+        yaml = Pathname.new(paths["config/database"].first || "")
+
+        config = if yaml.exist?
           require "erb"
-          YAML.load ERB.new(IO.read(yaml)).result
+          YAML.load(ERB.new(yaml.read).result) || {}
         elsif ENV['DATABASE_URL']
-          nil
+          # Value from ENV['DATABASE_URL'] is set to default database connection
+          # by Active Record.
+          {}
         else
           raise "Could not load database configuration. No such file - #{yaml}"
         end
+
+        config
       rescue Psych::SyntaxError => e
         raise "YAML syntax error occurred while parsing #{paths["config/database"].first}. " \
               "Please note that YAML must be consistently indented using spaces. Tabs are not allowed. " \
diff --git a/railties/lib/rails/application/default_middleware_stack.rb b/railties/lib/rails/application/default_middleware_stack.rb
index 570ff02c83..a00afe008c 100644
--- a/railties/lib/rails/application/default_middleware_stack.rb
+++ b/railties/lib/rails/application/default_middleware_stack.rb
@@ -11,11 +11,6 @@ module Rails
 
       def build_stack
         ActionDispatch::MiddlewareStack.new.tap do |middleware|
-          if rack_cache = load_rack_cache
-            require "action_dispatch/http/rack_cache"
-            middleware.use ::Rack::Cache, rack_cache
-          end
-
           if config.force_ssl
             middleware.use ::ActionDispatch::SSL, config.ssl_options
           end
@@ -26,6 +21,11 @@ module Rails
             middleware.use ::ActionDispatch::Static, paths["public"].first, config.static_cache_control
           end
 
+          if rack_cache = load_rack_cache
+            require "action_dispatch/http/rack_cache"
+            middleware.use ::Rack::Cache, rack_cache
+          end
+
           middleware.use ::Rack::Lock unless allow_concurrency?
           middleware.use ::Rack::Runtime
           middleware.use ::Rack::MethodOverride
diff --git a/railties/lib/rails/application/finisher.rb b/railties/lib/rails/application/finisher.rb
index 7a1bb1e25c..5b8509b2e9 100644
--- a/railties/lib/rails/application/finisher.rb
+++ b/railties/lib/rails/application/finisher.rb
@@ -22,6 +22,8 @@ module Rails
       initializer :add_builtin_route do |app|
         if Rails.env.development?
           app.routes.append do
+            get '/rails/mailers'         => "rails/mailers#index"
+            get '/rails/mailers/*path'   => "rails/mailers#preview"
             get '/rails/info/properties' => "rails/info#properties"
             get '/rails/info/routes'     => "rails/info#routes"
             get '/rails/info'            => "rails/info#index"
diff --git a/railties/lib/rails/application_controller.rb b/railties/lib/rails/application_controller.rb
new file mode 100644
index 0000000000..9a29ec21cf
--- /dev/null
+++ b/railties/lib/rails/application_controller.rb
@@ -0,0 +1,16 @@
+class Rails::ApplicationController < ActionController::Base # :nodoc:
+  self.view_paths = File.expand_path('../templates', __FILE__)
+  layout 'application'
+
+  protected
+
+  def require_local!
+    unless local_request?
+      render text: '<p>For security purposes, this information is only available to local requests.</p>', status: :forbidden
+    end
+  end
+
+  def local_request?
+    Rails.application.config.consider_all_requests_local || request.local?
+  end
+end
diff --git a/railties/lib/rails/commands/dbconsole.rb b/railties/lib/rails/commands/dbconsole.rb
index 3e4cc787c4..f6d8aec30d 100644
--- a/railties/lib/rails/commands/dbconsole.rb
+++ b/railties/lib/rails/commands/dbconsole.rb
@@ -81,14 +81,11 @@ module Rails
 
     def config
       @config ||= begin
-        cfg = begin
-          YAML.load(ERB.new(IO.read("config/database.yml")).result)
-        rescue SyntaxError, StandardError
-          require APP_PATH
-          Rails.application.config.database_configuration
+        if configurations[environment].blank?
+          raise ActiveRecord::AdapterNotSpecified, "'#{environment}' database is not configured. Available configuration: #{configurations.inspect}"
+        else
+          configurations[environment]
         end
-
-        cfg[environment] || abort("No database is configured for the environment '#{environment}'")
       end
     end
 
@@ -102,6 +99,12 @@ module Rails
 
     protected
 
+    def configurations
+      require APP_PATH
+      ActiveRecord::Base.configurations = Rails.application.config.database_configuration
+      ActiveRecord::Base.configurations
+    end
+
     def parse_arguments(arguments)
       options = {}
 
diff --git a/railties/lib/rails/commands/plugin.rb b/railties/lib/rails/commands/plugin.rb
index 837fe0ec10..f7a0b99005 100644
--- a/railties/lib/rails/commands/plugin.rb
+++ b/railties/lib/rails/commands/plugin.rb
@@ -2,6 +2,20 @@ if ARGV.first != "new"
   ARGV[0] = "--help"
 else
   ARGV.shift
+  unless ARGV.delete("--no-rc")
+    customrc = ARGV.index{ |x| x.include?("--rc=") }
+    railsrc = if customrc
+                File.expand_path(ARGV.delete_at(customrc).gsub(/--rc=/, ""))
+              else
+                File.join(File.expand_path("~"), '.railsrc')
+              end
+    if File.exist?(railsrc)
+      extra_args_string = File.read(railsrc)
+      extra_args = extra_args_string.split(/\n+/).map {|l| l.split}.flatten
+      puts "Using #{extra_args.join(" ")} from #{railsrc}"
+      ARGV.insert(1, *extra_args)
+    end
+  end
 end
 
 require 'rails/generators'
diff --git a/railties/lib/rails/commands/runner.rb b/railties/lib/rails/commands/runner.rb
index dd2ee5639e..3a71f8d3f8 100644
--- a/railties/lib/rails/commands/runner.rb
+++ b/railties/lib/rails/commands/runner.rb
@@ -9,7 +9,7 @@ if ARGV.first.nil?
 end
 
 ARGV.clone.options do |opts|
-  opts.banner = "Usage: rails runner [options] ('Some.ruby(code)' or a filename)"
+  opts.banner = "Usage: rails runner [options] [<'Some.ruby(code)'> | <filename.rb>]"
 
   opts.separator ""
 
@@ -22,14 +22,23 @@ ARGV.clone.options do |opts|
   opts.on("-h", "--help",
           "Show this help message.") { $stdout.puts opts; exit }
 
+    opts.separator ""
+    opts.separator "Examples: "
+
+    opts.separator "    rails runner 'puts Rails.env'"
+    opts.separator "        This runs the code `puts Rails.env` after loading the app"
+    opts.separator ""
+    opts.separator "    rails runner path/to/filename.rb"
+    opts.separator "        This runs the Ruby file located at `path/to/filename.rb` after loading the app"
+
   if RbConfig::CONFIG['host_os'] !~ /mswin|mingw/
     opts.separator ""
     opts.separator "You can also use runner as a shebang line for your executables:"
-    opts.separator "-------------------------------------------------------------"
-    opts.separator "#!/usr/bin/env #{File.expand_path($0)} runner"
+    opts.separator "    -------------------------------------------------------------"
+    opts.separator "    #!/usr/bin/env #{File.expand_path($0)} runner"
     opts.separator ""
-    opts.separator "Product.all.each { |p| p.price *= 2 ; p.save! }"
-    opts.separator "-------------------------------------------------------------"
+    opts.separator "    Product.all.each { |p| p.price *= 2 ; p.save! }"
+    opts.separator "    -------------------------------------------------------------"
   end
 
   opts.order! { |o| code_or_file ||= o } rescue retry
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 54a0f1c002..5c54cdaa70 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -2,7 +2,6 @@ require 'rails/railtie'
 require 'rails/engine/railties'
 require 'active_support/core_ext/module/delegation'
 require 'pathname'
-require 'rbconfig'
 
 module Rails
   # <tt>Rails::Engine</tt> allows you to wrap a specific Rails application or subset of
diff --git a/railties/lib/rails/generators/actions.rb b/railties/lib/rails/generators/actions.rb
index 366c72ebaa..afdbf5c241 100644
--- a/railties/lib/rails/generators/actions.rb
+++ b/railties/lib/rails/generators/actions.rb
@@ -9,7 +9,7 @@ module Rails
         @in_group = nil
       end
 
-      # Adds an entry into Gemfile for the supplied gem.
+      # Adds an entry into +Gemfile+ for the supplied gem.
       #
       #   gem "rspec", group: :test
       #   gem "technoweenie-restful-authentication", lib: "restful-authentication", source: "http://gems.github.com/"
@@ -61,7 +61,7 @@ module Rails
         end
       end
 
-      # Add the given source to Gemfile
+      # Add the given source to +Gemfile+
       #
       #   add_source "http://gems.github.com/"
       def add_source(source, options={})
@@ -72,10 +72,10 @@ module Rails
         end
       end
 
-      # Adds a line inside the Application class for config/application.rb.
+      # Adds a line inside the Application class for <tt>config/application.rb</tt>.
       #
-      # If options :env is specified, the line is appended to the corresponding
-      # file in config/environments.
+      # If options <tt>:env</tt> is specified, the line is appended to the corresponding
+      # file in <tt>config/environments</tt>.
       #
       #   environment do
       #     "config.autoload_paths += %W(#{config.root}/extras)"
@@ -116,7 +116,7 @@ module Rails
         end
       end
 
-      # Create a new file in the vendor/ directory. Code can be specified
+      # Create a new file in the <tt>vendor/</tt> directory. Code can be specified
       # in a block or a data string can be given.
       #
       #   vendor("sekrit.rb") do
@@ -143,7 +143,7 @@ module Rails
         create_file("lib/#{filename}", data, verbose: false, &block)
       end
 
-      # Create a new Rakefile with the provided code (either in a block or a string).
+      # Create a new +Rakefile+ with the provided code (either in a block or a string).
       #
       #   rakefile("bootstrap.rake") do
       #     project = ask("What is the UNIX name of your project?")
@@ -213,7 +213,7 @@ module Rails
         in_root { run("#{extify(:capify)} .", verbose: false) }
       end
 
-      # Make an entry in Rails routing file config/routes.rb
+      # Make an entry in Rails routing file <tt>config/routes.rb</tt>
       #
       #   route "root 'welcome#index'"
       def route(routing_code)
diff --git a/railties/lib/rails/generators/app_base.rb b/railties/lib/rails/generators/app_base.rb
index 2022b4ed3d..4988602aea 100644
--- a/railties/lib/rails/generators/app_base.rb
+++ b/railties/lib/rails/generators/app_base.rb
@@ -14,6 +14,7 @@ module Rails
       DATABASES.concat(JDBC_DATABASES)
 
       attr_accessor :rails_template
+      attr_accessor :app_template
       add_shebang_option!
 
       argument :app_path, type: :string
@@ -26,6 +27,9 @@ module Rails
         class_option :template,           type: :string, aliases: '-m',
                                           desc: "Path to some #{name} template (can be a filesystem path or URL)"
 
+        class_option :app_template,       type: :string, aliases: '-n',
+                                          desc: "Path to some #{name} template (can be a filesystem path or URL)"
+
         class_option :skip_gemfile,       type: :boolean, default: false,
                                           desc: "Don't create a Gemfile"
 
@@ -47,6 +51,9 @@ module Rails
         class_option :skip_sprockets,     type: :boolean, aliases: '-S', default: false,
                                           desc: 'Skip Sprockets files'
 
+        class_option :skip_spring,        type: :boolean, default: false,
+                                          desc: "Don't install Spring application preloader"
+
         class_option :database,           type: :string, aliases: '-d', default: 'sqlite3',
                                           desc: "Preconfigure for selected database (options: #{DATABASES.join('/')})"
 
@@ -109,6 +116,7 @@ module Rails
           jbuilder_gemfile_entry,
           sdoc_gemfile_entry,
           platform_dependent_gemfile_entry,
+          spring_gemfile_entry,
           @extra_entries].flatten.find_all(&@gem_filter)
       end
 
@@ -118,6 +126,10 @@ module Rails
         }.curry[@gem_filter]
       end
 
+      def remove_gem(name)
+        add_gem_entry_filter { |gem| gem.name != name }
+      end
+
       def builder
         @builder ||= begin
           builder_class = get_builder_class
@@ -158,6 +170,10 @@ module Rails
           @target.send :add_gem_entry_filter, *args, &block
         end
 
+        def remove_gem(*args, &block)
+          @target.send :remove_gem, *args, &block
+        end
+
         def method_missing(name, *args, &block)
           @commands << [name, args, block]
         end
@@ -176,7 +192,8 @@ module Rails
       def apply_rails_template
         @recorder = TemplateRecorder.new self
 
-        apply(rails_template, target: @recorder) if rails_template
+        apply(rails_template, target: self) if rails_template
+        apply(app_template, target: @recorder) if app_template
       rescue Thor::Error, LoadError, Errno::ENOENT => e
         raise Error, "The template [#{rails_template}] could not be loaded. Error: #{e}"
       end
@@ -206,13 +223,18 @@ module Rails
 
       def set_default_accessors!
         self.destination_root = File.expand_path(app_path, destination_root)
-        self.rails_template = case options[:template]
-          when /^https?:\/\//
-            options[:template]
-          when String
-            File.expand_path(options[:template], Dir.pwd)
-          else
-            options[:template]
+        self.rails_template = expand_template options[:template]
+        self.app_template = expand_template options[:app_template]
+      end
+
+      def expand_template(name)
+        case name
+        when /^https?:\/\//
+          name
+        when String
+          File.expand_path(name, Dir.pwd)
+        else
+          name
         end
       end
 
@@ -304,7 +326,7 @@ module Rails
                                     'Use SCSS for stylesheets')
         else
           gems << GemfileEntry.version('sass-rails',
-                                     '~> 4.0.0.rc1',
+                                     '~> 4.0.1',
                                      'Use SCSS for stylesheets')
         end
 
@@ -325,7 +347,7 @@ module Rails
 
       def jbuilder_gemfile_entry
         comment = 'Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder'
-        GemfileEntry.version('jbuilder', '~> 1.2', comment)
+        GemfileEntry.version('jbuilder', '~> 2.0', comment)
       end
 
       def sdoc_gemfile_entry
@@ -365,6 +387,12 @@ module Rails
         end
       end
 
+      def spring_gemfile_entry
+        return [] unless spring_install?
+        comment = 'Spring speeds up development by keeping your application running in the background. Read more: https://github.com/jonleighton/spring'
+        GemfileEntry.new('spring', nil, comment, group: :development)
+      end
+
       def bundle_command(command)
         say_status :run, "bundle #{command}"
 
@@ -388,8 +416,22 @@ module Rails
         end
       end
 
+      def bundle_install?
+        !(options[:skip_gemfile] || options[:skip_bundle] || options[:pretend])
+      end
+
+      def spring_install?
+        !options[:skip_spring] && Process.respond_to?(:fork)
+      end
+
       def run_bundle
-        bundle_command('install') unless options[:skip_gemfile] || options[:skip_bundle] || options[:pretend]
+        bundle_command('install') if bundle_install?
+      end
+
+      def generate_spring_binstubs
+        if bundle_install? && spring_install?
+          bundle_command("exec spring binstub --all")
+        end
       end
 
       def empty_directory_with_keep_file(destination, config = {})
diff --git a/railties/lib/rails/generators/base.rb b/railties/lib/rails/generators/base.rb
index cf33b13fd8..67bab96a22 100644
--- a/railties/lib/rails/generators/base.rb
+++ b/railties/lib/rails/generators/base.rb
@@ -296,7 +296,7 @@ module Rails
           end
         end
 
-        # Return the default value for the option name given doing a lookup in
+        # Returns the default value for the option name given doing a lookup in
         # Rails::Generators.options.
         def self.default_value_for_option(name, options)
           default_for_option(Rails::Generators.options, name, options, options[:default])
diff --git a/railties/lib/rails/generators/erb.rb b/railties/lib/rails/generators/erb.rb
index 73e986ee7f..cfd77097d5 100644
--- a/railties/lib/rails/generators/erb.rb
+++ b/railties/lib/rails/generators/erb.rb
@@ -5,6 +5,10 @@ module Erb # :nodoc:
     class Base < Rails::Generators::NamedBase #:nodoc:
       protected
 
+      def formats
+        format
+      end
+
       def format
         :html
       end
@@ -13,7 +17,7 @@ module Erb # :nodoc:
         :erb
       end
 
-      def filename_with_extensions(name)
+      def filename_with_extensions(name, format)
         [name, format, handler].compact.join(".")
       end
     end
diff --git a/railties/lib/rails/generators/erb/controller/controller_generator.rb b/railties/lib/rails/generators/erb/controller/controller_generator.rb
index 5f06734ab8..e62aece7c5 100644
--- a/railties/lib/rails/generators/erb/controller/controller_generator.rb
+++ b/railties/lib/rails/generators/erb/controller/controller_generator.rb
@@ -11,8 +11,10 @@ module Erb # :nodoc:
 
         actions.each do |action|
           @action = action
-          @path = File.join(base_path, filename_with_extensions(action))
-          template filename_with_extensions(:view), @path
+          Array(formats).each do |format|
+            @path = File.join(base_path, filename_with_extensions(action, format))
+            template filename_with_extensions(:view, format), @path
+          end
         end
       end
     end
diff --git a/railties/lib/rails/generators/erb/mailer/mailer_generator.rb b/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
index 7bcac30dde..66b17bd10e 100644
--- a/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
+++ b/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
@@ -5,8 +5,8 @@ module Erb # :nodoc:
     class MailerGenerator < ControllerGenerator # :nodoc:
       protected
 
-      def format
-        :text
+      def formats
+        [:text, :html]
       end
     end
   end
diff --git a/railties/lib/rails/generators/erb/mailer/templates/view.html.erb b/railties/lib/rails/generators/erb/mailer/templates/view.html.erb
new file mode 100644
index 0000000000..8bb7c2b768
--- /dev/null
+++ b/railties/lib/rails/generators/erb/mailer/templates/view.html.erb
@@ -0,0 +1,5 @@
+<h1><%= class_name %>#<%= @action %></h1>
+
+<p>
+  <%%= @greeting %>, find me in app/views/<%= @path %>
+</p>
diff --git a/railties/lib/rails/generators/erb/scaffold/scaffold_generator.rb b/railties/lib/rails/generators/erb/scaffold/scaffold_generator.rb
index bacbc2d280..b219f459ac 100644
--- a/railties/lib/rails/generators/erb/scaffold/scaffold_generator.rb
+++ b/railties/lib/rails/generators/erb/scaffold/scaffold_generator.rb
@@ -14,8 +14,10 @@ module Erb # :nodoc:
 
       def copy_view_files
         available_views.each do |view|
-          filename = filename_with_extensions(view)
-          template filename, File.join("app/views", controller_file_path, filename)
+          Array(formats).each do |format|
+            filename = filename_with_extensions(view, format)
+            template filename, File.join("app/views", controller_file_path, filename)
+          end
         end
       end
 
diff --git a/railties/lib/rails/generators/rails/app/app_generator.rb b/railties/lib/rails/generators/rails/app/app_generator.rb
index a2023886cd..d2eca5b2fb 100644
--- a/railties/lib/rails/generators/rails/app/app_generator.rb
+++ b/railties/lib/rails/generators/rails/app/app_generator.rb
@@ -78,6 +78,7 @@ module Rails
         template "routes.rb"
         template "application.rb"
         template "environment.rb"
+        template "secrets.yml"
 
         directory "environments"
         directory "initializers"
@@ -225,18 +226,19 @@ module Rails
         build(:vendor)
       end
 
-      def finish_template
-        build(:leftovers)
-      end
-
       def delete_js_folder_skipping_javascript
         if options[:skip_javascript]
           remove_dir 'app/assets/javascripts'
         end
       end
 
+      def finish_template
+        build(:leftovers)
+      end
+
       public_task :run_bundle
       public_task :replay_template
+      public_task :generate_spring_binstubs
 
     protected
 
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 ac41a0cadb..16fe50bab8 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/application.rb
+++ b/railties/lib/rails/generators/rails/app/templates/config/application.rb
@@ -15,7 +15,7 @@ require "action_mailer/railtie"
 
 # Require the gems listed in Gemfile, including any gems
 # you've limited to :test, :development, or :production.
-Bundler.require(:default, Rails.env)
+Bundler.require(*Rails.groups)
 
 module <%= app_const_base %>
   class Application < Rails::Application
@@ -30,10 +30,5 @@ module <%= app_const_base %>
     # 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.skip_sprockets? -%>
-
-    # Disable the asset pipeline.
-    config.assets.enabled = false
-<% end -%>
   end
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/frontbase.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/frontbase.yml
index c6dfd50d40..138e3a8664 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/frontbase.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/frontbase.yml
@@ -23,6 +23,7 @@ test:
   <<: *default
   database: <%= app_name %>_test
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
 production:
-  <<: *default
-  database: <%= app_name %>_production
+  url: <%%= ENV["DATABASE_URL"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/ibm_db.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/ibm_db.yml
index fe53cd0ea2..2cdb592eeb 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/ibm_db.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/ibm_db.yml
@@ -61,6 +61,7 @@ test:
   <<: *default
   database: <%= app_name[0,4] %>_tst
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
 production:
-  <<: *default
-  database: <%= app_name[0,8] %>
+  url: <%%= ENV["DATABASE_URL"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/jdbc.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/jdbc.yml
index be1dae332f..cefd30d519 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/jdbc.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/jdbc.yml
@@ -53,6 +53,7 @@ test:
   <<: *default
   url: jdbc:db://localhost/<%= app_name %>_test
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
 production:
-  <<: *default
-  url: jdbc:db://localhost/<%= app_name %>_production
+  url: <%%= ENV["DATABASE_URL"] %>
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 26e2a5976c..d31761349c 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
@@ -26,6 +26,6 @@ test:
   <<: *default
   database: <%= app_name %>_test
 
-production:
-  <<: *default
-  database: <%= app_name %>_production
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
+production: <%%= ENV["DATABASE_URL"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcpostgresql.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcpostgresql.yml
index ccd44cf54b..0d248dc197 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcpostgresql.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcpostgresql.yml
@@ -6,13 +6,20 @@
 default: &default
   adapter: postgresql
   encoding: unicode
-  username: <%= app_name %>
-  password:
 
 development:
   <<: *default
   database: <%= app_name %>_development
 
+  # The specified database role being used to connect to postgres.
+  # To create additional roles in postgres see `$ createuser --help`.
+  # When left blank, postgres will use the default role. This is
+  # the same name as the operating system user that initialized the database.
+  #username: <%= app_name %>
+
+  # The password associated with the postgres role (username).
+  #password:
+
   # Connect on a TCP socket. Omitted by default since the client uses a
   # domain socket that doesn't need configuration. Windows does not have
   # domain sockets, so uncomment these lines.
@@ -35,6 +42,7 @@ test:
   <<: *default
   database: <%= app_name %>_test
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
 production:
-  <<: *default
-  database: <%= app_name %>_production
+  url: <%%= ENV["DATABASE_URL"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcsqlite3.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcsqlite3.yml
index 28c36eb82f..66eba3bf0d 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcsqlite3.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/jdbcsqlite3.yml
@@ -18,6 +18,7 @@ test:
   <<: *default
   database: db/test.sqlite3
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
 production:
-  <<: *default
-  database: db/production.sqlite3
+  url: <%%= ENV["DATABASE_URL"] %>
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 3fc7ce28a1..d618fc28a6 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
@@ -1,4 +1,4 @@
-# MySQL.  Versions 4.1 and 5.0 are recommended.
+# MySQL.  Versions 5.0+ are recommended.
 #
 # Install the MYSQL driver
 #   gem install mysql2
@@ -32,6 +32,11 @@ test:
   <<: *default
   database: <%= app_name %>_test
 
+# Avoid production credentials in the repository,
+# instead read the configuration from the environment.
+#
+# Example:
+#   mysql2://myuser:mypass@localhost/somedatabase
+#
 production:
-  <<: *default
-  database: <%= app_name %>_production
+  url: <%%= ENV["DATABASE_URL"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/oracle.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/oracle.yml
index d5b52c969b..d469ec0f99 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/oracle.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/oracle.yml
@@ -32,6 +32,7 @@ test:
   <<: *default
   database: <%= app_name %>_test
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
 production:
-  <<: *default
-  database: <%= app_name %>_production
+  url: <%%= ENV["DATABASE_URL"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/postgresql.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/postgresql.yml
index eaeb82bddd..93f48656b2 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/postgresql.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/postgresql.yml
@@ -17,16 +17,23 @@
 default: &default
   adapter: postgresql
   encoding: unicode
-  # For details on connection pooling, see rails configration guide
+  # For details on connection pooling, see rails configuration guide
   # http://guides.rubyonrails.org/configuring.html#database-pooling
   pool: 5
-  username: <%= app_name %>
-  password:
 
 development:
   <<: *default
   database: <%= app_name %>_development
 
+  # The specified database role being used to connect to postgres.
+  # To create additional roles in postgres see `$ createuser --help`.
+  # When left blank, postgres will use the default role. This is
+  # the same name as the operating system user that initialized the database.
+  #username: <%= app_name %>
+
+  # The password associated with the postgres role (username).
+  #password:
+
   # Connect on a TCP socket. Omitted by default since the client uses a
   # domain socket that doesn't need configuration. Windows does not have
   # domain sockets, so uncomment these lines.
@@ -52,6 +59,11 @@ test:
   <<: *default
   database: <%= app_name %>_test
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
+#
+# Example:
+#   postgres://myuser:mypass@localhost/somedatabase
+#
 production:
-  <<: *default
-  database: <%= app_name %>_production
+  url: <%%= ENV["DATABASE_URL"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/sqlite3.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/sqlite3.yml
index 1c1a37ca8d..7312ddb6cd 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/sqlite3.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/sqlite3.yml
@@ -20,6 +20,11 @@ test:
   <<: *default
   database: db/test.sqlite3
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
+#
+# Example:
+#   sqlite3://myuser:mypass@localhost/full/path/to/somedatabase
+#
 production:
-  <<: *default
-  database: db/production.sqlite3
+  url: <%%= ENV["DATABASE_URL"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/databases/sqlserver.yml b/railties/lib/rails/generators/rails/app/templates/config/databases/sqlserver.yml
index 4855f66c0d..aa960e493e 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/databases/sqlserver.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/databases/sqlserver.yml
@@ -42,6 +42,7 @@ test:
   <<: *default
   database: <%= app_name %>_test
 
+# Do not keep production credentials in the repository,
+# instead read the configuration from the environment.
 production:
-  <<: *default
-  database: <%= app_name %>_production
+  url: <%%= ENV["DATABASE_URL"] %>
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 b724d468a2..cce4743a33 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
@@ -29,5 +29,10 @@ Rails.application.configure do
   # This option may cause significant delays in view rendering with a large
   # number of complex assets.
   config.assets.debug = true
+
+  # Adds additional error checking when serving assets at runtime.
+  # Checks for improperly declared sprockets dependencies.
+  # Raises helpful error messages.
+  config.assets.raise_runtime_errors = true
   <%- end -%>
 end
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 1dfc9f136b..3baa382bd6 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
@@ -70,7 +70,7 @@ Rails.application.configure do
   # config.action_mailer.raise_delivery_errors = false
 
   # Enable locale fallbacks for I18n (makes lookups for any locale fall back to
-  # the I18n.default_locale when a translation can not be found).
+  # the I18n.default_locale when a translation cannot be found).
   config.i18n.fallbacks = true
 
   # Send deprecation notices to registered listeners.
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/secret_token.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/secrets.yml
index f3cc6098a3..6e2c45e119 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/secret_token.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/secrets.yml
@@ -7,6 +7,16 @@
 # no regular words or you'll be exposed to dictionary attacks.
 # You can use `rake secret` to generate a secure secret key.
 
-# Make sure your secret_key_base is kept private
+# Make sure the secrets in this file are kept private
 # if you're sharing your code publicly.
-Rails.application.config.secret_key_base = '<%= app_secret %>'
+
+development:
+  secret_key_base: <%= app_secret %>
+
+test:
+  secret_key_base: <%= app_secret %>
+
+# Do not keep production secrets in the repository,
+# instead read values from the environment.
+production:
+  secret_key_base: <%%= ENV["RAILS_SECRET_KEY_BASE"] %>
diff --git a/railties/lib/rails/generators/rails/app/templates/test/test_helper.rb b/railties/lib/rails/generators/rails/app/templates/test/test_helper.rb
index 4fd060341e..4ade1a0bdc 100644
--- a/railties/lib/rails/generators/rails/app/templates/test/test_helper.rb
+++ b/railties/lib/rails/generators/rails/app/templates/test/test_helper.rb
@@ -4,8 +4,6 @@ require 'rails/test_help'
 
 class ActiveSupport::TestCase
 <% unless options[:skip_active_record] -%>
-  ActiveRecord::Migration.check_pending!
-
   # Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
   #
   # Note: You'll currently still have to declare fixtures explicitly in integration tests
diff --git a/railties/lib/rails/generators/rails/plugin/templates/Gemfile b/railties/lib/rails/generators/rails/plugin/templates/Gemfile
index d576784415..88ec4e6354 100644
--- a/railties/lib/rails/generators/rails/plugin/templates/Gemfile
+++ b/railties/lib/rails/generators/rails/plugin/templates/Gemfile
@@ -39,5 +39,7 @@ end
 <% end -%>
 
 <% end -%>
+<% unless defined?(JRUBY_VERSION) -%>
 # To use debugger
 # gem 'debugger'
+<% end -%>
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 a0e5553e44..e4a2bc2b0f 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
@@ -9,7 +9,7 @@ module Rails
       # should give you
       #
       #   namespace :admin do
-      #     namespace :users
+      #     namespace :users do
       #       resources :products
       #     end
       #   end
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 3334b189bf..85dee1a066 100644
--- a/railties/lib/rails/generators/test_unit/mailer/mailer_generator.rb
+++ b/railties/lib/rails/generators/test_unit/mailer/mailer_generator.rb
@@ -4,11 +4,18 @@ module TestUnit # :nodoc:
   module Generators # :nodoc:
     class MailerGenerator < Base # :nodoc:
       argument :actions, type: :array, default: [], banner: "method method"
-      check_class_collision suffix: "Test"
+
+      def check_class_collision
+        class_collisions "#{class_name}Test", "#{class_name}Preview"
+      end
 
       def create_test_files
         template "functional_test.rb", File.join('test/mailers', class_path, "#{file_name}_test.rb")
       end
+
+      def create_preview_files
+        template "preview.rb", File.join('test/mailers/previews', class_path, "#{file_name}_preview.rb")
+      end
     end
   end
 end
diff --git a/railties/lib/rails/generators/test_unit/mailer/templates/preview.rb b/railties/lib/rails/generators/test_unit/mailer/templates/preview.rb
new file mode 100644
index 0000000000..3bfd5426e8
--- /dev/null
+++ b/railties/lib/rails/generators/test_unit/mailer/templates/preview.rb
@@ -0,0 +1,13 @@
+<% module_namespacing do -%>
+# Preview all emails at http://localhost:3000/rails/mailers/<%= file_path %>
+class <%= class_name %>Preview < ActionMailer::Preview
+<% actions.each do |action| -%>
+
+  # Preview this email at http://localhost:3000/rails/mailers/<%= file_path %>/<%= action %>
+  def <%= action %>
+    <%= class_name %>.<%= action %>
+  end
+<% end -%>
+
+end
+<% end -%>
diff --git a/railties/lib/rails/generators/testing/behaviour.rb b/railties/lib/rails/generators/testing/behaviour.rb
index 7576eba6e0..8e9028a3fb 100644
--- a/railties/lib/rails/generators/testing/behaviour.rb
+++ b/railties/lib/rails/generators/testing/behaviour.rb
@@ -61,9 +61,11 @@ module Rails
         # You can provide a configuration hash as second argument. This method returns the output
         # printed by the generator.
         def run_generator(args=self.default_arguments, config={})
-          capture(:stdout) do
-            args += ['--skip-bundle'] unless args.include? '--dev'
-            self.generator_class.start(args, config.reverse_merge(destination_root: destination_root))
+          without_thor_debug do
+            capture(:stdout) do
+              args += ['--skip-bundle'] unless args.include? '--dev'
+              self.generator_class.start(args, config.reverse_merge(destination_root: destination_root))
+            end
           end
         end
 
@@ -100,6 +102,14 @@ module Rails
             dirname, file_name = File.dirname(absolute), File.basename(absolute).sub(/\.rb$/, '')
             Dir.glob("#{dirname}/[0-9]*_*.rb").grep(/\d+_#{file_name}.rb$/).first
           end
+
+          # TODO: remove this once Bundler 1.5.2 is released
+          def without_thor_debug # :nodoc:
+            thor_debug, ENV['THOR_DEBUG'] = ENV['THOR_DEBUG'], nil
+            yield
+          ensure
+            ENV['THOR_DEBUG'] = thor_debug
+          end
       end
     end
   end
diff --git a/railties/lib/rails/info_controller.rb b/railties/lib/rails/info_controller.rb
index 85ea11b4e7..908c4ce65e 100644
--- a/railties/lib/rails/info_controller.rb
+++ b/railties/lib/rails/info_controller.rb
@@ -1,9 +1,9 @@
+require 'rails/application_controller'
 require 'action_dispatch/routing/inspector'
 
-class Rails::InfoController < ActionController::Base # :nodoc:
-  self.view_paths = File.expand_path('../templates', __FILE__)
+class Rails::InfoController < Rails::ApplicationController # :nodoc:
   prepend_view_path ActionDispatch::DebugExceptions::RESCUES_TEMPLATE_PATH
-  layout -> { request.xhr? ? nil : 'application' }
+  layout -> { request.xhr? ? false : 'application' }
 
   before_filter :require_local!
 
@@ -20,16 +20,4 @@ class Rails::InfoController < ActionController::Base # :nodoc:
     @routes_inspector = ActionDispatch::Routing::RoutesInspector.new(_routes.routes)
     @page_title = 'Routes'
   end
-
-  protected
-
-  def require_local!
-    unless local_request?
-      render text: '<p>For security purposes, this information is only available to local requests.</p>', status: :forbidden
-    end
-  end
-
-  def local_request?
-    Rails.application.config.consider_all_requests_local || request.local?
-  end
 end
diff --git a/railties/lib/rails/mailers_controller.rb b/railties/lib/rails/mailers_controller.rb
new file mode 100644
index 0000000000..dd318f52e5
--- /dev/null
+++ b/railties/lib/rails/mailers_controller.rb
@@ -0,0 +1,73 @@
+require 'rails/application_controller'
+
+class Rails::MailersController < Rails::ApplicationController # :nodoc:
+  prepend_view_path ActionDispatch::DebugExceptions::RESCUES_TEMPLATE_PATH
+
+  before_filter :require_local!
+  before_filter :find_preview, only: :preview
+
+  def index
+    @previews = ActionMailer::Preview.all
+    @page_title = "Mailer Previews"
+  end
+
+  def preview
+    if params[:path] == @preview.preview_name
+      @page_title = "Mailer Previews for #{@preview.preview_name}"
+      render action: 'mailer'
+    else
+      email = File.basename(params[:path])
+
+      if @preview.email_exists?(email)
+        @email = @preview.call(email)
+
+        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
+          else
+            raise AbstractController::ActionNotFound, "Email part '#{part_type}' not found in #{@preview.name}##{email}"
+          end
+        else
+          @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}"
+      end
+    end
+  end
+
+  protected
+    def find_preview
+      candidates = []
+      params[:path].to_s.scan(%r{/|$}){ candidates << $` }
+      preview = candidates.detect{ |candidate| ActionMailer::Preview.exists?(candidate) }
+
+      if preview
+        @preview = ActionMailer::Preview.find(preview)
+      else
+        raise AbstractController::ActionNotFound, "Mailer preview '#{params[:path]}' not found"
+      end
+    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 }
+        end
+      else
+        @email
+      end
+    end
+
+    def find_part(format)
+      if @email.multipart?
+        @email.parts.find{ |p| p.mime_type == format }
+      elsif @email.mime_type == format
+        @email
+      end
+    end
+end
\ No newline at end of file
diff --git a/railties/lib/rails/paths.rb b/railties/lib/rails/paths.rb
index f512aefb23..117bb37487 100644
--- a/railties/lib/rails/paths.rb
+++ b/railties/lib/rails/paths.rb
@@ -24,7 +24,7 @@ module Rails
     #
     # Notice that when you add a path using +add+, the path object created already
     # contains the path with the same path value given to +add+. In some situations,
-    # you may not want this behavior, so you can give :with as option.
+    # you may not want this behavior, so you can give <tt>:with</tt> as option.
     #
     #   root.add "config/routes", with: "config/routes.rb"
     #   root["config/routes"].inspect # => ["config/routes.rb"]
diff --git a/railties/lib/rails/railtie.rb b/railties/lib/rails/railtie.rb
index 89ca8cbe11..c63e0c0758 100644
--- a/railties/lib/rails/railtie.rb
+++ b/railties/lib/rails/railtie.rb
@@ -22,7 +22,7 @@ module Rails
   #
   # * creating initializers
   # * configuring a Rails framework for the application, like setting a generator
-  # * +adding config.*+ keys to the environment
+  # * adding <tt>config.*</tt> keys to the environment
   # * setting up a subscriber with ActiveSupport::Notifications
   # * adding rake tasks
   #
@@ -63,8 +63,8 @@ module Rails
   #     end
   #   end
   #
-  # Finally, you can also pass :before and :after as option to initializer, in case
-  # you want to couple it with a specific step in the initialization process.
+  # Finally, you can also pass <tt>:before</tt> and <tt>:after</tt> as option to initializer,
+  # in case you want to couple it with a specific step in the initialization process.
   #
   # == Configuration
   #
diff --git a/railties/lib/rails/templates/layouts/application.html.erb b/railties/lib/rails/templates/layouts/application.html.erb
index 50a4755e45..5aecaa712a 100644
--- a/railties/lib/rails/templates/layouts/application.html.erb
+++ b/railties/lib/rails/templates/layouts/application.html.erb
@@ -29,7 +29,7 @@
   </style>
 </head>
 <body>
-<h2>Your App: <%= link_to 'properties', '/rails/info/properties' %> | <%= link_to 'routes', '/rails/info/routes' %></h2>
+
 <%= yield %>
 
 </body>
diff --git a/railties/lib/rails/templates/rails/mailers/email.html.erb b/railties/lib/rails/templates/rails/mailers/email.html.erb
new file mode 100644
index 0000000000..977feb922b
--- /dev/null
+++ b/railties/lib/rails/templates/rails/mailers/email.html.erb
@@ -0,0 +1,98 @@
+<!DOCTYPE html>
+<html><head>
+<meta name="viewport" content="width=device-width" />
+<style type="text/css">
+  header {
+    width: 100%;
+    padding: 10px 0 0 0;
+    margin: 0;
+    background: white;
+    font: 12px "Lucida Grande", sans-serif;
+    border-bottom: 1px solid #dedede;
+    overflow: hidden;
+  }
+
+  dl {
+    margin: 0 0 10px 0;
+    padding: 0;
+  }
+
+  dt {
+    width: 80px;
+    padding: 1px;
+    float: left;
+    clear: left;
+    text-align: right;
+    color: #7f7f7f;
+  }
+
+  dd {
+    margin-left: 90px; /* 80px + 10px */
+    padding: 1px;
+  }
+
+  iframe {
+    border: 0;
+    width: 100%;
+    height: 800px;
+  }
+</style>
+</head>
+
+<body>
+<header>
+  <dl>
+    <% if @email.respond_to?(:smtp_envelope_from) && Array(@email.from) != Array(@email.smtp_envelope_from) %>
+      <dt>SMTP-From:</dt>
+      <dd><%= @email.smtp_envelope_from %></dd>
+    <% end %>
+
+    <% if @email.respond_to?(:smtp_envelope_to) && @email.to != @email.smtp_envelope_to %>
+      <dt>SMTP-To:</dt>
+      <dd><%= @email.smtp_envelope_to %></dd>
+    <% end %>
+
+    <dt>From:</dt>
+    <dd><%= @email.header['from'] %></dd>
+
+    <% if @email.reply_to %>
+      <dt>Reply-To:</dt>
+      <dd><%= @email.header['reply-to'] %></dd>
+    <% end %>
+
+    <dt>To:</dt>
+    <dd><%= @email.header['to'] %></dd>
+
+    <% if @email.cc %>
+      <dt>CC:</dt>
+      <dd><%= @email.header['cc'] %></dd>
+    <% end %>
+
+    <dt>Date:</dt>
+    <dd><%= Time.current.rfc2822 %></dd>
+
+    <dt>Subject:</dt>
+    <dd><strong><%= @email.subject %></strong></dd>
+
+    <% 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 %>
+      </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>
+      </dd>
+    <% end %>
+  </dl>
+</header>
+
+<iframe seamless name="messageBody" src="?part=<%= Rack::Utils.escape(@part.mime_type) %>"></iframe>
+
+</body>
+</html>
\ No newline at end of file
diff --git a/railties/lib/rails/templates/rails/mailers/index.html.erb b/railties/lib/rails/templates/rails/mailers/index.html.erb
new file mode 100644
index 0000000000..c4c9757d57
--- /dev/null
+++ b/railties/lib/rails/templates/rails/mailers/index.html.erb
@@ -0,0 +1,8 @@
+<% @previews.each do |preview| %>
+<h3><%= link_to preview.preview_name.titleize, "/rails/mailers/#{preview.preview_name}" %></h3>
+<ul>
+<% preview.emails.each do |email| %>
+<li><%= link_to email, "/rails/mailers/#{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
new file mode 100644
index 0000000000..607c8d1677
--- /dev/null
+++ b/railties/lib/rails/templates/rails/mailers/mailer.html.erb
@@ -0,0 +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>
+<% end %>
+</ul>
diff --git a/railties/lib/rails/test_help.rb b/railties/lib/rails/test_help.rb
index be801befc2..2e6356343d 100644
--- a/railties/lib/rails/test_help.rb
+++ b/railties/lib/rails/test_help.rb
@@ -11,10 +11,12 @@ require 'rails/generators/test_case'
 # Config Rails backtrace in tests.
 require 'rails/backtrace_cleaner'
 if ENV["BACKTRACE"].nil?
-  MiniTest.backtrace_filter = Rails.backtrace_cleaner
+  Minitest.backtrace_filter = Rails.backtrace_cleaner
 end
 
 if defined?(ActiveRecord::Base)
+  ActiveRecord::Migration.maintain_test_schema!
+
   class ActiveSupport::TestCase
     include ActiveRecord::TestFixtures
     self.fixture_path = "#{Rails.root}/test/fixtures/"
diff --git a/railties/lib/rails/test_unit/testing.rake b/railties/lib/rails/test_unit/testing.rake
index 38107e77b2..285e2ce846 100644
--- a/railties/lib/rails/test_unit/testing.rake
+++ b/railties/lib/rails/test_unit/testing.rake
@@ -1,4 +1,3 @@
-require 'rbconfig'
 require 'rake/testtask'
 require 'rails/test_unit/sub_test_task'
 
diff --git a/railties/lib/rails/version.rb b/railties/lib/rails/version.rb
index 5a6d8d0983..923cab4e2a 100644
--- a/railties/lib/rails/version.rb
+++ b/railties/lib/rails/version.rb
@@ -3,7 +3,7 @@ module Rails
     MAJOR = 4
     MINOR = 1
     TINY  = 0
-    PRE   = "beta"
+    PRE   = "beta1"
 
     STRING = [MAJOR, MINOR, TINY, PRE].compact.join(".")
   end
diff --git a/railties/lib/rails/welcome_controller.rb b/railties/lib/rails/welcome_controller.rb
index 45b764fa6b..de9cd18b01 100644
--- a/railties/lib/rails/welcome_controller.rb
+++ b/railties/lib/rails/welcome_controller.rb
@@ -1,6 +1,7 @@
-class Rails::WelcomeController < ActionController::Base # :nodoc:
-  self.view_paths = File.expand_path('../templates', __FILE__)
-  layout nil
+require 'rails/application_controller'
+
+class Rails::WelcomeController < Rails::ApplicationController # :nodoc:
+  layout false
 
   def index
   end
diff --git a/railties/test/abstract_unit.rb b/railties/test/abstract_unit.rb
index 643cc6b0ee..ade08d3f5a 100644
--- a/railties/test/abstract_unit.rb
+++ b/railties/test/abstract_unit.rb
@@ -14,6 +14,6 @@ require 'rails/all'
 module TestApp
   class Application < Rails::Application
     config.root = File.dirname(__FILE__)
-    config.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
+    secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
   end
 end
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index 03a735b1c1..6158c416d7 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -250,7 +250,7 @@ module ApplicationTests
 
     test "Use key_generator when secret_key_base is set" do
       make_basic_app do |app|
-        app.config.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
+        app.secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
         app.config.session_store :disabled
       end
 
@@ -268,6 +268,74 @@ module ApplicationTests
       assert_equal 'some_value', verifier.verify(last_response.body)
     end
 
+    test "application verifier can be used in the entire application" do
+      make_basic_app do |app|
+        app.secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
+        app.config.session_store :disabled
+      end
+
+      message = app.message_verifier(:sensitive_value).generate("some_value")
+
+      assert_equal 'some_value', Rails.application.message_verifier(:sensitive_value).verify(message)
+
+      secret = app.key_generator.generate_key('sensitive_value')
+      verifier = ActiveSupport::MessageVerifier.new(secret)
+      assert_equal 'some_value', verifier.verify(message)
+    end
+
+    test "application verifier can build different verifiers" do
+      make_basic_app do |app|
+        app.secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
+        app.config.session_store :disabled
+      end
+
+      default_verifier = app.message_verifier(:sensitive_value)
+      text_verifier = app.message_verifier(:text)
+
+      message = text_verifier.generate('some_value')
+
+      assert_equal 'some_value', text_verifier.verify(message)
+      assert_raises ActiveSupport::MessageVerifier::InvalidSignature do
+        default_verifier.verify(message)
+      end
+
+      assert_equal default_verifier.object_id, app.message_verifier(:sensitive_value).object_id
+      assert_not_equal default_verifier.object_id, text_verifier.object_id
+    end
+
+    test "secrets.secret_key_base is used when config/secrets.yml is present" do
+      app_file 'config/secrets.yml', <<-YAML
+        development:
+          secret_key_base: 3b7cd727ee24e8444053437c36cc66c3
+      YAML
+
+      require "#{app_path}/config/environment"
+      assert_equal '3b7cd727ee24e8444053437c36cc66c3', app.secrets.secret_key_base
+    end
+
+    test "secret_key_base is copied from config to secrets when not set" do
+      remove_file "config/secrets.yml"
+      app_file 'config/initializers/secret_token.rb', <<-RUBY
+        Rails.application.config.secret_key_base = "3b7cd727ee24e8444053437c36cc66c3"
+      RUBY
+
+      require "#{app_path}/config/environment"
+      assert_equal '3b7cd727ee24e8444053437c36cc66c3', app.secrets.secret_key_base
+    end
+
+    test "custom secrets saved in config/secrets.yml are loaded in app secrets" do
+      app_file 'config/secrets.yml', <<-YAML
+        development:
+          secret_key_base: 3b7cd727ee24e8444053437c36cc66c3
+          aws_access_key_id: myamazonaccesskeyid
+          aws_secret_access_key: myamazonsecretaccesskey
+      YAML
+
+      require "#{app_path}/config/environment"
+      assert_equal 'myamazonaccesskeyid', app.secrets.aws_access_key_id
+      assert_equal 'myamazonsecretaccesskey', app.secrets.aws_secret_access_key
+    end
+
     test "protect from forgery is the default in a new app" do
       make_basic_app
 
@@ -459,7 +527,7 @@ module ApplicationTests
       require "#{app_path}/config/environment"
       require 'action_view/base'
 
-      assert ActionView::Resolver.caching?
+      assert_equal true, ActionView::Resolver.caching?
     end
 
     test "config.action_view.cache_template_loading without cache_classes default" do
@@ -467,7 +535,7 @@ module ApplicationTests
       require "#{app_path}/config/environment"
       require 'action_view/base'
 
-      assert !ActionView::Resolver.caching?
+      assert_equal false, ActionView::Resolver.caching?
     end
 
     test "config.action_view.cache_template_loading = false" do
@@ -478,7 +546,7 @@ module ApplicationTests
       require "#{app_path}/config/environment"
       require 'action_view/base'
 
-      assert !ActionView::Resolver.caching?
+      assert_equal false, ActionView::Resolver.caching?
     end
 
     test "config.action_view.cache_template_loading = true" do
@@ -489,7 +557,21 @@ module ApplicationTests
       require "#{app_path}/config/environment"
       require 'action_view/base'
 
-      assert ActionView::Resolver.caching?
+      assert_equal true, ActionView::Resolver.caching?
+    end
+
+    test "config.action_view.cache_template_loading with cache_classes in an environment" do
+      build_app(initializers: true)
+      add_to_env_config "development", "config.cache_classes = false"
+
+      # These requires are to emulate an engine loading Action View before the application
+      require 'action_view'
+      require 'action_view/railtie'
+      require 'action_view/base'
+
+      require "#{app_path}/config/environment"
+
+      assert_equal false, ActionView::Resolver.caching?
     end
 
     test "config.action_dispatch.show_exceptions is sent in env" do
diff --git a/railties/test/application/initializers/frameworks_test.rb b/railties/test/application/initializers/frameworks_test.rb
index 83104acf3c..3601a58f67 100644
--- a/railties/test/application/initializers/frameworks_test.rb
+++ b/railties/test/application/initializers/frameworks_test.rb
@@ -216,7 +216,7 @@ module ApplicationTests
         require "#{app_path}/config/environment"
         orig_database_url = ENV.delete("DATABASE_URL")
         orig_rails_env, Rails.env = Rails.env, 'development'
-        database_url_db_name = "db/database_url_db.sqlite3"
+        database_url_db_name = File.join(app_path, "db/database_url_db.sqlite3")
         ENV["DATABASE_URL"] = "sqlite3://:@localhost/#{database_url_db_name}"
         ActiveRecord::Base.establish_connection
         assert ActiveRecord::Base.connection
diff --git a/railties/test/application/initializers/i18n_test.rb b/railties/test/application/initializers/i18n_test.rb
index 97df073ec7..bc34897cdf 100644
--- a/railties/test/application/initializers/i18n_test.rb
+++ b/railties/test/application/initializers/i18n_test.rb
@@ -183,5 +183,50 @@ en:
       load_app
       assert_fallbacks ca: [:ca, :"es-ES", :es, :'en-US', :en]
     end
+
+    test "config.i18n.enforce_available_locales is set to true by default and avoids I18n warnings" do
+      add_to_config <<-RUBY
+        config.i18n.default_locale = :it
+      RUBY
+
+      output = capture(:stderr) { load_app }
+      assert_no_match %r{deprecated.*enforce_available_locales}, output
+      assert_equal true, I18n.enforce_available_locales
+
+      assert_raise I18n::InvalidLocale do
+        I18n.locale = :es
+      end
+    end
+
+    test "disable config.i18n.enforce_available_locales" do
+      add_to_config <<-RUBY
+        config.i18n.enforce_available_locales = false
+        config.i18n.default_locale = :fr
+      RUBY
+
+      output = capture(:stderr) { load_app }
+      assert_no_match %r{deprecated.*enforce_available_locales}, output
+      assert_equal false, I18n.enforce_available_locales
+
+      assert_nothing_raised do
+        I18n.locale = :es
+      end
+    end
+
+    test "default config.i18n.enforce_available_locales does not override I18n.enforce_available_locales" do
+      I18n.enforce_available_locales = false
+
+      add_to_config <<-RUBY
+        config.i18n.default_locale = :fr
+      RUBY
+
+      output = capture(:stderr) { load_app }
+      assert_no_match %r{deprecated.*enforce_available_locales}, output
+      assert_equal false, I18n.enforce_available_locales
+
+      assert_nothing_raised do
+        I18n.locale = :es
+      end
+    end
   end
 end
diff --git a/railties/test/application/mailer_previews_test.rb b/railties/test/application/mailer_previews_test.rb
new file mode 100644
index 0000000000..c588fd7012
--- /dev/null
+++ b/railties/test/application/mailer_previews_test.rb
@@ -0,0 +1,428 @@
+require 'isolation/abstract_unit'
+require 'rack/test'
+module ApplicationTests
+  class MailerPreviewsTest < ActiveSupport::TestCase
+    include ActiveSupport::Testing::Isolation
+    include Rack::Test::Methods
+
+    def setup
+      build_app
+      boot_rails
+    end
+
+    def teardown
+      teardown_app
+    end
+
+    test "/rails/mailers is accessible in development" do
+      app("development")
+      get "/rails/mailers"
+      assert_equal 200, last_response.status
+    end
+
+    test "/rails/mailers is not accessible in production" do
+      app("production")
+      get "/rails/mailers"
+      assert_equal 404, last_response.status
+    end
+
+    test "mailer previews are loaded from the default preview_path" 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"
+      assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+      assert_match '<li><a href="/rails/mailers/notifier/foo">foo</a></li>', last_response.body
+    end
+
+    test "mailer previews are loaded from a custom preview_path" do
+      add_to_config "config.action_mailer.preview_path = '#{app_path}/lib/mailer_previews'"
+
+      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
+
+      app_file 'lib/mailer_previews/notifier_preview.rb', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      app('development')
+
+      get "/rails/mailers"
+      assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+      assert_match '<li><a href="/rails/mailers/notifier/foo">foo</a></li>', last_response.body
+    end
+
+    test "mailer previews are reloaded across requests" do
+      app('development')
+
+      get "/rails/mailers"
+      assert_no_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+
+      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
+
+      get "/rails/mailers"
+      assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+
+      remove_file 'test/mailers/previews/notifier_preview.rb'
+      sleep(1)
+
+      get "/rails/mailers"
+      assert_no_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+    end
+
+    test "mailer preview actions are added and removed" 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"
+      assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+      assert_match '<li><a href="/rails/mailers/notifier/foo">foo</a></li>', last_response.body
+      assert_no_match '<li><a href="/rails/mailers/notifier/bar">bar</a></li>', last_response.body
+
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            mail to: "to@example.org"
+          end
+
+          def bar
+            mail to: "to@example.net"
+          end
+        end
+      RUBY
+
+      text_template 'notifier/foo', <<-RUBY
+        Hello, World!
+      RUBY
+
+      text_template 'notifier/bar', <<-RUBY
+        Goodbye, World!
+      RUBY
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+
+          def bar
+            Notifier.bar
+          end
+        end
+      RUBY
+
+      sleep(1)
+
+      get "/rails/mailers"
+      assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+      assert_match '<li><a href="/rails/mailers/notifier/foo">foo</a></li>', last_response.body
+      assert_match '<li><a href="/rails/mailers/notifier/bar">bar</a></li>', last_response.body
+
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            mail to: "to@example.org"
+          end
+        end
+      RUBY
+
+      remove_file 'app/views/notifier/bar.text.erb'
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      sleep(1)
+
+      get "/rails/mailers"
+      assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+      assert_match '<li><a href="/rails/mailers/notifier/foo">foo</a></li>', last_response.body
+      assert_no_match '<li><a href="/rails/mailers/notifier/bar">bar</a></li>', last_response.body
+    end
+
+    test "mailer previews are reloaded from a custom preview_path" do
+      add_to_config "config.action_mailer.preview_path = '#{app_path}/lib/mailer_previews'"
+
+      app('development')
+
+      get "/rails/mailers"
+      assert_no_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+
+      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
+
+      app_file 'lib/mailer_previews/notifier_preview.rb', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      get "/rails/mailers"
+      assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+
+      remove_file 'lib/mailer_previews/notifier_preview.rb'
+      sleep(1)
+
+      get "/rails/mailers"
+      assert_no_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+    end
+
+    test "mailer preview not found" do
+      app('development')
+      get "/rails/mailers/notifier"
+      assert last_response.not_found?
+      assert_match "Mailer preview &#39;notifier&#39; not found", last_response.body
+    end
+
+    test "mailer preview email not found" 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/notifier/bar"
+      assert last_response.not_found?
+      assert_match "Email &#39;bar&#39; not found in NotifierPreview", last_response.body
+    end
+
+    test "mailer preview email part not found" 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/notifier/foo?part=text%2Fhtml"
+      assert last_response.not_found?
+      assert_match "Email part &#39;text/html&#39; not found in NotifierPreview#foo", last_response.body
+    end
+
+    test "message header uses full display names" do
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "Ruby on Rails <core@rubyonrails.org>"
+
+          def foo
+            mail to: "Andrew White <andyw@pixeltrix.co.uk>",
+                 cc: "David Heinemeier Hansson <david@heinemeierhansson.com>"
+          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 "Ruby on Rails &lt;core@rubyonrails.org&gt;", last_response.body
+      assert_match "Andrew White &lt;andyw@pixeltrix.co.uk&gt;", last_response.body
+      assert_match "David Heinemeier Hansson &lt;david@heinemeierhansson.com&gt;", last_response.body
+    end
+
+    test "part menu selects correct option" do
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            mail to: "to@example.org"
+          end
+        end
+      RUBY
+
+      html_template 'notifier/foo', <<-RUBY
+        <p>Hello, World!</p>
+      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.html"
+      assert_equal 200, last_response.status
+      assert_match '<option selected value="?part=text%2Fhtml">View as HTML email</option>', last_response.body
+
+      get "/rails/mailers/notifier/foo.txt"
+      assert_equal 200, last_response.status
+      assert_match '<option selected value="?part=text%2Fplain">View as plain-text email</option>', last_response.body
+    end
+
+    private
+      def build_app
+        super
+        app_file "config/routes.rb", "Rails.application.routes.draw do; end"
+      end
+
+      def mailer(name, contents)
+        app_file("app/mailers/#{name}.rb", contents)
+      end
+
+      def mailer_preview(name, contents)
+        app_file("test/mailers/previews/#{name}_preview.rb", contents)
+      end
+
+      def html_template(name, contents)
+        app_file("app/views/#{name}.html.erb", contents)
+      end
+
+      def text_template(name, contents)
+        app_file("app/views/#{name}.text.erb", contents)
+      end
+  end
+end
diff --git a/railties/test/application/middleware/session_test.rb b/railties/test/application/middleware/session_test.rb
index 14a56176f5..31a64c2f5a 100644
--- a/railties/test/application/middleware/session_test.rb
+++ b/railties/test/application/middleware/session_test.rb
@@ -318,7 +318,7 @@ module ApplicationTests
 
       add_to_config <<-RUBY
         config.secret_token = "3b7cd727ee24e8444053437c36cc66c4"
-        config.secret_key_base = nil
+        secrets.secret_key_base = nil
       RUBY
 
       require "#{app_path}/config/environment"
diff --git a/railties/test/application/middleware_test.rb b/railties/test/application/middleware_test.rb
index 20d1d76d78..1557b90d27 100644
--- a/railties/test/application/middleware_test.rb
+++ b/railties/test/application/middleware_test.rb
@@ -61,7 +61,7 @@ module ApplicationTests
 
       boot!
 
-      assert_equal "Rack::Cache", middleware.first
+      assert middleware.include?("Rack::Cache")
     end
 
     test "ActiveRecord::Migration::CheckPending is present when active_record.migration_error is set to :page_load" do
diff --git a/railties/test/application/rake/dbs_test.rb b/railties/test/application/rake/dbs_test.rb
index 4d348c6b4b..35d9c31c1e 100644
--- a/railties/test/application/rake/dbs_test.rb
+++ b/railties/test/application/rake/dbs_test.rb
@@ -1,4 +1,5 @@
 require "isolation/abstract_unit"
+require "active_support/core_ext/string/strip"
 
 module ApplicationTests
   module RakeTests
@@ -16,11 +17,11 @@ module ApplicationTests
       end
 
       def database_url_db_name
-        "db/database_url_db.sqlite3"
+        File.join(app_path, "db/database_url_db.sqlite3")
       end
 
       def set_database_url
-        ENV['DATABASE_URL'] = "sqlite3://:@localhost/#{database_url_db_name}"
+        ENV['DATABASE_URL'] = File.join("sqlite3://:@localhost", database_url_db_name)
         # ensure it's using the DATABASE_URL
         FileUtils.rm_rf("#{app_path}/config/database.yml")
       end
@@ -60,7 +61,7 @@ module ApplicationTests
           `rails generate model book title:string;
            bundle exec rake db:migrate`
           output = `bundle exec rake db:migrate:status`
-          assert_match(/database:\s+\S+#{expected[:database]}/, output)
+          assert_match(%r{database:\s+\S*#{Regexp.escape(expected[:database])}}, output)
           assert_match(/up\s+\d{14}\s+Create books/, output)
         end
       end
@@ -126,7 +127,7 @@ module ApplicationTests
            bundle exec rake db:migrate db:structure:dump`
           structure_dump = File.read("db/structure.sql")
           assert_match(/CREATE TABLE \"books\"/, structure_dump)
-          `bundle exec rake db:drop db:structure:load`
+          `bundle exec rake environment db:drop db:structure:load`
           assert_match(/#{expected[:database]}/,
                         ActiveRecord::Base.connection_config[:database])
           require "#{app_path}/app/models/book"
@@ -153,7 +154,7 @@ module ApplicationTests
           `rails generate model book title:string;
            bundle exec rake db:migrate db:structure:dump db:test:load_structure`
           ActiveRecord::Base.configurations = Rails.application.config.database_configuration
-          ActiveRecord::Base.establish_connection 'test'
+          ActiveRecord::Base.establish_connection :test
           require "#{app_path}/app/models/book"
           #if structure is not loaded correctly, exception would be raised
           assert Book.count, 0
@@ -166,6 +167,15 @@ module ApplicationTests
         require "#{app_path}/config/environment"
         db_test_load_structure
       end
+
+      test 'db:test deprecation' do
+        require "#{app_path}/config/environment"
+        Dir.chdir(app_path) do
+          output = `bundle exec rake db:migrate db:test:prepare 2>&1`
+          assert_equal "WARNING: db:test:prepare is deprecated. The Rails test helper now maintains " \
+                       "your test schema automatically, see the release notes for details.\n", output
+        end
+      end
     end
   end
 end
diff --git a/railties/test/application/rake_test.rb b/railties/test/application/rake_test.rb
index 08316d80e6..317e73245c 100644
--- a/railties/test/application/rake_test.rb
+++ b/railties/test/application/rake_test.rb
@@ -187,7 +187,7 @@ module ApplicationTests
     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 db:test:clone test`
+         bundle exec rake db:migrate test`
       end
 
       assert_match(/7 runs, 13 assertions, 0 failures, 0 errors/, output)
@@ -197,7 +197,7 @@ module ApplicationTests
     def test_scaffold_with_references_columns_tests_pass_by_default
       output = Dir.chdir(app_path) do
         `rails generate scaffold LineItems product:references cart:belongs_to;
-         bundle exec rake db:migrate db:test:clone test`
+         bundle exec rake db:migrate test`
       end
 
       assert_match(/7 runs, 13 assertions, 0 failures, 0 errors/, output)
@@ -208,7 +208,8 @@ module ApplicationTests
       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 db:test:clone 2>&1 --trace`
+         bundle exec rake db:migrate;
+         bundle exec rake db:test:clone 2>&1 --trace`
       end
       assert_match(/Execute db:test:clone_structure/, output)
     end
@@ -217,7 +218,8 @@ module ApplicationTests
       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 db:test:prepare 2>&1 --trace`
+         bundle exec rake db:migrate;
+         bundle exec rake db:test:prepare 2>&1 --trace`
       end
       assert_match(/Execute db:test:load_structure/, output)
     end
diff --git a/railties/test/application/test_test.rb b/railties/test/application/test_test.rb
index 6f2f328588..a223180169 100644
--- a/railties/test/application/test_test.rb
+++ b/railties/test/application/test_test.rb
@@ -67,10 +67,55 @@ module ApplicationTests
       assert_match %r{/app/test/unit/failing_test\.rb}, output
     end
 
+    test "migrations" do
+      output  = script('generate model user name:string')
+      version = output.match(/(\d+)_create_users\.rb/)[1]
+
+      app_file 'test/models/user_test.rb', <<-RUBY
+        require 'test_helper'
+
+        class UserTest < ActiveSupport::TestCase
+          test "user" do
+            User.create! name: "Jon"
+          end
+        end
+      RUBY
+      app_file 'db/schema.rb', ''
+
+      assert_unsuccessful_run "models/user_test.rb", "Migrations are pending"
+
+      app_file 'db/schema.rb', <<-RUBY
+        ActiveRecord::Schema.define(version: #{version}) do
+          create_table :users do |t|
+            t.string :name
+          end
+        end
+      RUBY
+
+      app_file 'config/initializers/disable_maintain_test_schema.rb', <<-RUBY
+        Rails.application.config.active_record.maintain_test_schema = false
+      RUBY
+
+      assert_unsuccessful_run "models/user_test.rb", "Could not find table 'users'"
+
+      File.delete "#{app_path}/config/initializers/disable_maintain_test_schema.rb"
+
+      result = assert_successful_test_run('models/user_test.rb')
+      assert !result.include?("create_table(:users)")
+    end
+
     private
+      def assert_unsuccessful_run(name, message)
+        result = run_test_file(name)
+        assert_not_equal 0, $?.to_i
+        assert result.include?(message)
+        result
+      end
+
       def assert_successful_test_run(name)
         result = run_test_file(name)
         assert_equal 0, $?.to_i, result
+        result
       end
 
       def run_test_file(name, options = {})
@@ -83,7 +128,7 @@ module ApplicationTests
         env["RUBYLIB"] = $:.join(':')
 
         Dir.chdir(app_path) do
-          `#{env_string(env)} #{Gem.ruby} #{args.join(' ')}`
+          `#{env_string(env)} #{Gem.ruby} #{args.join(' ')} 2>&1`
         end
       end
 
diff --git a/railties/test/commands/dbconsole_test.rb b/railties/test/commands/dbconsole_test.rb
index edb92b3aa2..24db395e6e 100644
--- a/railties/test/commands/dbconsole_test.rb
+++ b/railties/test/commands/dbconsole_test.rb
@@ -2,29 +2,74 @@ require 'abstract_unit'
 require 'rails/commands/dbconsole'
 
 class Rails::DBConsoleTest < ActiveSupport::TestCase
-  def teardown
-    %w[PGUSER PGHOST PGPORT PGPASSWORD].each{|key| ENV.delete(key)}
-  end
 
-  def test_config
-    Rails::DBConsole.const_set(:APP_PATH, "erb")
-
-    app_config({})
-    capture_abort { Rails::DBConsole.new.config }
-    assert aborted
-    assert_match(/No database is configured for the environment '\w+'/, output)
 
-    app_config(test: "with_init")
-    assert_equal Rails::DBConsole.new.config, "with_init"
-
-    app_db_file("test:\n  without_init")
-    assert_equal Rails::DBConsole.new.config, "without_init"
-
-    app_db_file("test:\n  <%= Rails.something_app_specific %>")
-    assert_equal Rails::DBConsole.new.config, "with_init"
+  def setup
+    Rails::DBConsole.const_set('APP_PATH', 'rails/all')
+  end
 
-    app_db_file("test:\n\ninvalid")
-    assert_equal Rails::DBConsole.new.config, "with_init"
+  def teardown
+    Rails::DBConsole.send(:remove_const, 'APP_PATH')
+    %w[PGUSER PGHOST PGPORT PGPASSWORD DATABASE_URL].each{|key| ENV.delete(key)}
+  end
+
+  def test_config_with_db_config_only
+    config_sample = {
+      "test"=> {
+        "adapter"=> "sqlite3",
+        "host"=> "localhost",
+        "port"=> "9000",
+        "database"=> "foo_test",
+        "user"=> "foo",
+        "password"=> "bar",
+        "pool"=> "5",
+        "timeout"=> "3000"
+      }
+    }
+    app_db_config(config_sample)
+    assert_equal Rails::DBConsole.new.config, config_sample["test"]
+  end
+
+  def test_config_with_no_db_config
+    app_db_config(nil)
+    assert_raise(ActiveRecord::AdapterNotSpecified) {
+      Rails::DBConsole.new.config
+    }
+  end
+
+  def test_config_with_database_url_only
+    ENV['DATABASE_URL'] = 'postgresql://foo:bar@localhost:9000/foo_test?pool=5&timeout=3000'
+    app_db_config(nil)
+    expected = {
+      "adapter"  => "postgresql",
+      "host"     => "localhost",
+      "port"     => 9000,
+      "database" => "foo_test",
+      "username" => "foo",
+      "password" => "bar",
+      "pool"     => "5",
+      "timeout"  => "3000"
+    }.sort
+    assert_equal expected, Rails::DBConsole.new.config.sort
+  end
+
+  def test_config_choose_database_url_if_exists
+    host = "database-url-host.com"
+    ENV['DATABASE_URL'] = "postgresql://foo:bar@#{host}:9000/foo_test?pool=5&timeout=3000"
+    sample_config = {
+      "test" => {
+        "adapter"  => "postgresql",
+        "host"     => "not-the-#{host}",
+        "port"     => 9000,
+        "database" => "foo_test",
+        "username" => "foo",
+        "password" => "bar",
+        "pool"     => "5",
+        "timeout"  => "3000"
+      }
+    }
+    app_db_config(sample_config)
+    assert_equal host, Rails::DBConsole.new.config["host"]
   end
 
   def test_env
@@ -177,6 +222,10 @@ class Rails::DBConsoleTest < ActiveSupport::TestCase
 
   private
 
+  def app_db_config(results)
+    Rails.application.config.stubs(:database_configuration).returns(results || {})
+  end
+
   def dbconsole
     @dbconsole ||= Rails::DBConsole.new(nil)
   end
@@ -197,11 +246,4 @@ class Rails::DBConsoleTest < ActiveSupport::TestCase
     end
   end
 
-  def app_db_file(result)
-    IO.stubs(:read).with("config/database.yml").returns(result)
-  end
-
-  def app_config(result)
-    Rails.application.config.stubs(:database_configuration).returns(result.stringify_keys)
-  end
 end
diff --git a/railties/test/configuration/middleware_stack_proxy_test.rb b/railties/test/configuration/middleware_stack_proxy_test.rb
index 2442cb995d..6f3e45f320 100644
--- a/railties/test/configuration/middleware_stack_proxy_test.rb
+++ b/railties/test/configuration/middleware_stack_proxy_test.rb
@@ -39,7 +39,7 @@ module Rails
         @stack.swap :foo
         @stack.delete :foo
 
-        mock = MiniTest::Mock.new
+        mock = Minitest::Mock.new
         mock.expect :send, nil, [:swap, :foo]
         mock.expect :send, nil, [:delete, :foo]
 
@@ -50,7 +50,7 @@ module Rails
       private
 
       def assert_playback(msg_name, args)
-        mock = MiniTest::Mock.new
+        mock = Minitest::Mock.new
         mock.expect :send, nil, [msg_name, args]
         @stack.merge_into(mock)
         mock.verify
diff --git a/railties/test/generators/app_generator_test.rb b/railties/test/generators/app_generator_test.rb
index f89ff66e3e..be109cc598 100644
--- a/railties/test/generators/app_generator_test.rb
+++ b/railties/test/generators/app_generator_test.rb
@@ -163,56 +163,71 @@ class AppGeneratorTest < Rails::Generators::TestCase
     end
   end
 
-  def test_add_gemfile_entry
-    template = Tempfile.open 'my_template'
-    template.puts 'gemfile_entry "tenderlove"'
-    template.flush
+  def test_arbitrary_code
+    output = Tempfile.open('my_template') do |template|
+      template.puts 'puts "You are using Rails version #{Rails::VERSION::STRING}."'
+      template.close
+      run_generator([destination_root, "-m", template.path])
+    end
+    assert_match 'You are using', output
+  end
 
-    run_generator([destination_root, "-m", template.path])
-    assert_file "Gemfile", /tenderlove/
-  ensure
-    template.close
-    template.unlink
+  def test_add_gemfile_entry
+    Tempfile.open('my_template') do |template|
+      template.puts 'gemfile_entry "tenderlove"'
+      template.flush
+      template.close
+      run_generator([destination_root, "-n", template.path])
+      assert_file "Gemfile", /tenderlove/
+    end
   end
 
   def test_add_skip_entry
-    template = Tempfile.open 'my_template'
-    template.puts 'add_gem_entry_filter { |gem| gem.name != "jbuilder" }'
-    template.flush
+    Tempfile.open 'my_template' do |template|
+      template.puts 'add_gem_entry_filter { |gem| gem.name != "jbuilder" }'
+      template.close
 
-    run_generator([destination_root, "-m", template.path])
-    assert_file "Gemfile" do |contents|
-      assert_no_match 'jbuilder', contents
+      run_generator([destination_root, "-n", template.path])
+      assert_file "Gemfile" do |contents|
+        assert_no_match 'jbuilder', contents
+      end
     end
-  ensure
-    template.close
-    template.unlink
   end
 
-  def test_skip_turbolinks_when_it_is_not_on_gemfile
-    template = Tempfile.open 'my_template'
-    template.puts 'add_gem_entry_filter { |gem| gem.name != "turbolinks" }'
-    template.flush
+  def test_remove_gem
+    Tempfile.open 'my_template' do |template|
+      template.puts 'remove_gem "jbuilder"'
+      template.close
 
-    run_generator([destination_root, "-m", template.path])
-    assert_file "Gemfile" do |contents|
-      assert_no_match 'turbolinks', contents
+      run_generator([destination_root, "-n", template.path])
+      assert_file "Gemfile" do |contents|
+        assert_no_match 'jbuilder', contents
+      end
     end
+  end
 
-    assert_file "app/views/layouts/application.html.erb" do |contents|
-      assert_no_match 'turbolinks', contents
-    end
+  def test_skip_turbolinks_when_it_is_not_on_gemfile
+    Tempfile.open 'my_template' do |template|
+      template.puts 'add_gem_entry_filter { |gem| gem.name != "turbolinks" }'
+      template.flush
 
-    assert_file "app/views/layouts/application.html.erb" do |contents|
-      assert_no_match('data-turbolinks-track', contents)
-    end
+      run_generator([destination_root, "-n", template.path])
+      assert_file "Gemfile" do |contents|
+        assert_no_match 'turbolinks', contents
+      end
 
-    assert_file "app/assets/javascripts/application.js" do |contents|
-      assert_no_match 'turbolinks', contents
+      assert_file "app/views/layouts/application.html.erb" do |contents|
+        assert_no_match 'turbolinks', contents
+      end
+
+      assert_file "app/views/layouts/application.html.erb" do |contents|
+        assert_no_match('data-turbolinks-track', contents)
+      end
+
+      assert_file "app/assets/javascripts/application.js" do |contents|
+        assert_no_match 'turbolinks', contents
+      end
     end
-  ensure
-    template.close
-    template.unlink
   end
 
   def test_config_another_database
@@ -291,7 +306,6 @@ class AppGeneratorTest < Rails::Generators::TestCase
     run_generator [destination_root, "--skip-sprockets"]
     assert_file "config/application.rb" do |content|
       assert_match(/#\s+require\s+["']sprockets\/railtie["']/, content)
-      assert_match(/config\.assets\.enabled = false/, content)
     end
     assert_file "Gemfile" do |content|
       assert_no_match(/sass-rails/, content)
@@ -438,6 +452,34 @@ class AppGeneratorTest < Rails::Generators::TestCase
     assert_file "foo bar/config/initializers/session_store.rb", /key: '_foo_bar/
   end
 
+  def test_spring
+    run_generator
+    assert_file "Gemfile", /gem 'spring', \s+group: :development/
+  end
+
+  def test_spring_binstubs
+    generator.stubs(:bundle_command).with('install')
+    generator.expects(:bundle_command).with('exec spring binstub --all').once
+    quietly { generator.invoke_all }
+  end
+
+  def test_spring_no_fork
+    Process.stubs(:respond_to?).with(:fork).returns(false)
+    run_generator
+
+    assert_file "Gemfile" do |content|
+      assert_no_match(/spring/, content)
+    end
+  end
+
+  def test_skip_spring
+    run_generator [destination_root, "--skip-spring"]
+
+    assert_file "Gemfile" do |content|
+      assert_no_match(/spring/, content)
+    end
+  end
+
 protected
 
   def action(*args, &block)
diff --git a/railties/test/generators/generators_test_helper.rb b/railties/test/generators/generators_test_helper.rb
index 32a3d072c9..77ec2f1c0c 100644
--- a/railties/test/generators/generators_test_helper.rb
+++ b/railties/test/generators/generators_test_helper.rb
@@ -1,10 +1,14 @@
 require 'abstract_unit'
+require 'active_support/core_ext/module/remove_method'
 require 'rails/generators'
 require 'rails/generators/test_case'
 
 module Rails
-  def self.root
-    @root ||= File.expand_path(File.join(File.dirname(__FILE__), '..', 'fixtures'))
+  class << self
+    remove_possible_method :root
+    def root
+      @root ||= File.expand_path(File.join(File.dirname(__FILE__), '..', 'fixtures'))
+    end
   end
 end
 Rails.application.config.root = Rails.root
diff --git a/railties/test/generators/mailer_generator_test.rb b/railties/test/generators/mailer_generator_test.rb
index 6b2351fc1a..d209801f60 100644
--- a/railties/test/generators/mailer_generator_test.rb
+++ b/railties/test/generators/mailer_generator_test.rb
@@ -1,7 +1,6 @@
 require 'generators/generators_test_helper'
 require 'rails/generators/mailer/mailer_generator'
 
-
 class MailerGeneratorTest < Rails::Generators::TestCase
   include GeneratorsTestHelper
   arguments %w(notifier foo bar)
@@ -23,8 +22,11 @@ class MailerGeneratorTest < Rails::Generators::TestCase
   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)
+    Object.send :const_set, :Notifier, Class.new
+    content = capture(:stderr){ run_generator }
+    assert_match(/The name 'Notifier' is either already used in your application or reserved/, content)
+  ensure
+    Object.send :remove_const, :Notifier
   end
 
   def test_invokes_default_test_framework
@@ -34,9 +36,37 @@ class MailerGeneratorTest < Rails::Generators::TestCase
       assert_match(/test "foo"/, test)
       assert_match(/test "bar"/, test)
     end
+    assert_file "test/mailers/previews/notifier_preview.rb" do |preview|
+      assert_match(/\# Preview all emails at http:\/\/localhost\:3000\/rails\/mailers\/notifier/, preview)
+      assert_match(/class NotifierPreview < ActionMailer::Preview/, preview)
+      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/notifier\/foo/, preview)
+      assert_instance_method :foo, preview do |foo|
+        assert_match(/Notifier.foo/, foo)
+      end
+      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/notifier\/bar/, preview)
+      assert_instance_method :bar, preview do |bar|
+        assert_match(/Notifier.bar/, bar)
+      end
+    end
   end
 
-  def test_invokes_default_template_engine
+  def test_check_test_class_collision
+    Object.send :const_set, :NotifierTest, Class.new
+    content = capture(:stderr){ run_generator }
+    assert_match(/The name 'NotifierTest' is either already used in your application or reserved/, content)
+  ensure
+    Object.send :remove_const, :NotifierTest
+  end
+
+  def test_check_preview_class_collision
+    Object.send :const_set, :NotifierPreview, Class.new
+    content = capture(:stderr){ run_generator }
+    assert_match(/The name 'NotifierPreview' is either already used in your application or reserved/, content)
+  ensure
+    Object.send :remove_const, :NotifierPreview
+  end
+
+  def test_invokes_default_text_template_engine
     run_generator
     assert_file "app/views/notifier/foo.text.erb" do |view|
       assert_match(%r(app/views/notifier/foo\.text\.erb), view)
@@ -49,6 +79,19 @@ class MailerGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_invokes_default_html_template_engine
+    run_generator
+    assert_file "app/views/notifier/foo.html.erb" do |view|
+      assert_match(%r(app/views/notifier/foo\.html\.erb), view)
+      assert_match(/<%= @greeting %>/, view)
+    end
+
+    assert_file "app/views/notifier/bar.html.erb" do |view|
+      assert_match(%r(app/views/notifier/bar\.html\.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/notifier"
@@ -65,7 +108,13 @@ class MailerGeneratorTest < Rails::Generators::TestCase
       assert_match(/class Farm::Animal < ActionMailer::Base/, mailer)
       assert_match(/en\.farm\.animal\.moos\.subject/, mailer)
     end
+    assert_file "test/mailers/previews/farm/animal_preview.rb" do |preview|
+      assert_match(/\# Preview all emails at http:\/\/localhost\:3000\/rails\/mailers\/farm\/animal/, preview)
+      assert_match(/class Farm::AnimalPreview < ActionMailer::Preview/, preview)
+      assert_match(/\# Preview this email at http:\/\/localhost\:3000\/rails\/mailers\/farm\/animal\/moos/, preview)
+    end
     assert_file "app/views/farm/animal/moos.text.erb"
+    assert_file "app/views/farm/animal/moos.html.erb"
   end
 
   def test_actions_are_turned_into_methods
diff --git a/railties/test/generators/plugin_generator_test.rb b/railties/test/generators/plugin_generator_test.rb
index c6b91e7cba..932cd75bcb 100644
--- a/railties/test/generators/plugin_generator_test.rb
+++ b/railties/test/generators/plugin_generator_test.rb
@@ -35,6 +35,12 @@ class PluginGeneratorTest < Rails::Generators::TestCase
 
     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
+
+    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
@@ -58,6 +64,17 @@ class PluginGeneratorTest < Rails::Generators::TestCase
     assert_file "test/integration/navigation_test.rb", /ActionDispatch::IntegrationTest/
   end
 
+  def test_inclusion_of_debugger
+    run_generator [destination_root, '--full']
+    if defined?(JRUBY_VERSION)
+      assert_file "Gemfile" do |content|
+        assert_no_match(/debugger/, content)
+      end
+    else
+      assert_file "Gemfile", /# gem 'debugger'/
+    end
+  end
+
   def test_generating_test_files_in_full_mode_without_unit_test_files
     run_generator [destination_root, "-T", "--full"]
 
@@ -309,7 +326,7 @@ class PluginGeneratorTest < Rails::Generators::TestCase
   end
 
   def test_creating_plugin_in_app_directory_adds_gemfile_entry
-    # simulate application existance
+    # simulate application existence
     gemfile_path = "#{Rails.root}/Gemfile"
     Object.const_set('APP_PATH', Rails.root)
     FileUtils.touch gemfile_path
@@ -323,7 +340,7 @@ class PluginGeneratorTest < Rails::Generators::TestCase
   end
 
   def test_skipping_gemfile_entry
-    # simulate application existance
+    # simulate application existence
     gemfile_path = "#{Rails.root}/Gemfile"
     Object.const_set('APP_PATH', Rails.root)
     FileUtils.touch gemfile_path
diff --git a/railties/test/generators/shared_generator_tests.rb b/railties/test/generators/shared_generator_tests.rb
index 7184639d23..8e198d5fe1 100644
--- a/railties/test/generators/shared_generator_tests.rb
+++ b/railties/test/generators/shared_generator_tests.rb
@@ -26,11 +26,17 @@ module SharedGeneratorTests
     default_files.each { |path| assert_file path }
   end
 
-  def test_generation_runs_bundle_install
-    generator([destination_root]).expects(:bundle_command).with('install').once
+  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 }
   end
 
+  def test_generation_runs_bundle_install
+    assert_generates_with_bundler
+  end
+
   def test_plugin_new_generate_pretend
     run_generator ["testapp", "--pretend"]
     default_files.each{ |path| assert_no_file File.join("testapp",path) }
@@ -96,15 +102,13 @@ module SharedGeneratorTests
   end
 
   def test_dev_option
-    generator([destination_root], dev: true).expects(:bundle_command).with('install').once
-    quietly { generator.invoke_all }
+    assert_generates_with_bundler dev: true
     rails_path = File.expand_path('../../..', Rails.root)
     assert_file 'Gemfile', /^gem\s+["']rails["'],\s+path:\s+["']#{Regexp.escape(rails_path)}["']$/
   end
 
   def test_edge_option
-    generator([destination_root], edge: true).expects(:bundle_command).with('install').once
-    quietly { generator.invoke_all }
+    assert_generates_with_bundler edge: true
     assert_file 'Gemfile', %r{^gem\s+["']rails["'],\s+github:\s+["']#{Regexp.escape("rails/rails")}["']$}
   end
 
diff --git a/railties/test/isolation/abstract_unit.rb b/railties/test/isolation/abstract_unit.rb
index 913e2b5e29..a1f1973563 100644
--- a/railties/test/isolation/abstract_unit.rb
+++ b/railties/test/isolation/abstract_unit.rb
@@ -93,7 +93,8 @@ module TestHelpers
     # Build an application by invoking the generator and going through the whole stack.
     def build_app(options = {})
       @prev_rails_env = ENV['RAILS_ENV']
-      ENV['RAILS_ENV'] = 'development'
+      ENV['RAILS_ENV']             = 'development'
+      ENV['RAILS_SECRET_KEY_BASE'] ||= SecureRandom.hex(16)
 
       FileUtils.rm_rf(app_path)
       FileUtils.cp_r(app_template_path, app_path)
@@ -117,9 +118,26 @@ module TestHelpers
         end
       end
 
+      File.open("#{app_path}/config/database.yml", "w") do |f|
+        f.puts <<-YAML
+        default: &default
+          adapter: sqlite3
+          pool: 5
+          timeout: 5000
+        development:
+          <<: *default
+          database: db/development.sqlite3
+        test:
+          <<: *default
+          database: db/test.sqlite3
+        production:
+          <<: *default
+          database: db/production.sqlite3
+        YAML
+      end
+
       add_to_config <<-RUBY
         config.eager_load = false
-        config.secret_key_base = "3b7cd727ee24e8444053437c36cc66c4"
         config.session_store :cookie_store, key: "_myapp_session"
         config.active_support.deprecation = :log
         config.action_controller.allow_forgery_protection = false
@@ -139,7 +157,7 @@ module TestHelpers
 
       app = Class.new(Rails::Application)
       app.config.eager_load = false
-      app.config.secret_key_base = "3b7cd727ee24e8444053437c36cc66c4"
+      app.secrets.secret_key_base = "3b7cd727ee24e8444053437c36cc66c4"
       app.config.session_store :cookie_store, key: "_myapp_session"
       app.config.active_support.deprecation = :log
 
diff --git a/railties/test/rails_info_controller_test.rb b/railties/test/rails_info_controller_test.rb
index e45a5228a1..a9b237d0a5 100644
--- a/railties/test/rails_info_controller_test.rb
+++ b/railties/test/rails_info_controller_test.rb
@@ -1,7 +1,5 @@
 require 'abstract_unit'
 
-ActionController::Base.superclass.send(:include, ActionView::Layouts)
-
 module ActionController
   class Base
     include ActionController::Testing