15 files changed, 156 insertions, 36 deletions

diff --git a/guides/source/active_job_basics.md b/guides/source/active_job_basics.md
index a114686f0f..e36c0f899f 100644
--- a/guides/source/active_job_basics.md
+++ b/guides/source/active_job_basics.md
@@ -83,7 +83,7 @@ Note that you can define `perform` with as many arguments as you want.
 Enqueue a job like so:
 
 ```ruby
-# Enqueue a job to be performed as soon the queuing system is
+# Enqueue a job to be performed as soon as the queuing system is
 # free.
 GuestsCleanupJob.perform_later guest
 ```
diff --git a/guides/source/active_record_migrations.md b/guides/source/active_record_migrations.md
index 67881e6087..5aa5dc4f60 100644
--- a/guides/source/active_record_migrations.md
+++ b/guides/source/active_record_migrations.md
@@ -454,8 +454,6 @@ number of digits after the decimal point.
 are using a dynamic value (such as a date), the default will only be calculated
 the first time (i.e. on the date the migration is applied).
 * `index`        Adds an index for the column.
-* `required`     Adds `required: true` for `belongs_to` associations and
-`null: false` to the column in the migration.
 
 Some adapters may support additional options; see the adapter specific API docs
 for further information.
diff --git a/guides/source/active_record_validations.md b/guides/source/active_record_validations.md
index dd4d9f55fa..fe42cec158 100644
--- a/guides/source/active_record_validations.md
+++ b/guides/source/active_record_validations.md
@@ -457,21 +457,6 @@ class Person < ActiveRecord::Base
 end
 ```
 
-This helper counts characters by default, but you can split the value in a
-different way using the `:tokenizer` option:
-
-```ruby
-class Essay < ActiveRecord::Base
-  validates :content, length: {
-    minimum: 300,
-    maximum: 400,
-    tokenizer: lambda { |str| str.split(/\s+/) },
-    too_short: "must have at least %{count} words",
-    too_long: "must have at most %{count} words"
-  }
-end
-```
-
 Note that the default error messages are plural (e.g., "is too short (minimum
 is %{count} characters)"). For this reason, when `:minimum` is 1 you should
 provide a personalized message or use `presence: true` instead. When
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index f6fc255c24..181dca4b71 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -1710,6 +1710,20 @@ The method `parameterize` normalizes its receiver in a way that can be used in p
 "Kurt Gödel".parameterize # => "kurt-godel"
 ```
 
+To preserve the case of the string, set the `preserve_case` argument to true. By default, `preserve_case` is set to false.
+
+```ruby
+"John Smith".parameterize(preserve_case: true) # => "John-Smith"
+"Kurt Gödel".parameterize(preserve_case: true) # => "Kurt-Godel"
+```
+
+To use a custom separator, override the `separator` argument.
+
+```ruby
+"John Smith".parameterize(separator: "_") # => "john\_smith"
+"Kurt Gödel".parameterize(separator: "_") # => "kurt\_godel"
+```
+
 In fact, the result string is wrapped in an instance of `ActiveSupport::Multibyte::Chars`.
 
 NOTE: Defined in `active_support/core_ext/string/inflections.rb`.
diff --git a/guides/source/api_app.md b/guides/source/api_app.md
index feaaff166a..fb3127555e 100644
--- a/guides/source/api_app.md
+++ b/guides/source/api_app.md
@@ -221,7 +221,7 @@ For instance, using the `stale?` method:
 
 ```ruby
 def show
- @post = Post.find(params[:id])
+  @post = Post.find(params[:id])
 
   if stale?(last_modified: @post.updated_at)
     render json: @post
@@ -240,7 +240,7 @@ cross-client caching in the call to `stale?`:
 
 ```ruby
 def show
- @post = Post.find(params[:id])
+  @post = Post.find(params[:id])
 
   if stale?(last_modified: @post.updated_at, public: true)
     render json: @post
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index 996050d667..c272daac28 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -240,13 +240,15 @@ class CreateAppointments < ActiveRecord::Migration
 end
 ```
 
-The collection of join models can be managed via the API. For example, if you assign
+The collection of join models can be managed via the [`has_many` association methods](#has-many-association-reference).
+For example, if you assign:
 
 ```ruby
 physician.patients = patients
 ```
 
-new join models are created for newly associated objects, and if some are gone their rows are deleted.
+Then new join models are automatically created for the newly associated objects.
+If some that existed previously are now missing, then their join rows are automatically deleted.
 
 WARNING: Automatic deletion of join models is direct, no destroy callbacks are triggered.
 
diff --git a/guides/source/autoloading_and_reloading_constants.md b/guides/source/autoloading_and_reloading_constants.md
index 2b6d7e4044..5126d87bee 100644
--- a/guides/source/autoloading_and_reloading_constants.md
+++ b/guides/source/autoloading_and_reloading_constants.md
@@ -790,7 +790,7 @@ Constant Reloading
 When `config.cache_classes` is false Rails is able to reload autoloaded
 constants.
 
-For example, in you're in a console session and edit some file behind the
+For example, if you're in a console session and edit some file behind the
 scenes, the code can be reloaded with the `reload!` command:
 
 ```
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 6d3ca8baac..09f7007603 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -35,7 +35,7 @@ In general, the work of configuring Rails means configuring the components of Ra
 For example, the `config/application.rb` file includes this setting:
 
 ```ruby
-config.autoload_paths += %W(#{config.root}/extras)
+config.time_zone = 'Central Time (US & Canada)'
 ```
 
 This is a setting for Rails itself. If you want to pass settings to individual Rails components, you can do so via the same `config` object in `config/application.rb`:
@@ -199,7 +199,7 @@ The full set of methods that can be used in this block are as follows:
 Every Rails application comes with a standard set of middleware which it uses in this order in the development environment:
 
 * `ActionDispatch::SSL` forces every request to be under HTTPS protocol. Will be available if `config.force_ssl` is set to `true`. Options passed to this can be configured by using `config.ssl_options`.
-* `ActionDispatch::Static` is used to serve static assets. Disabled if `config.public_file_server.enabled` is `false`. Set `config.static_index` if you need to serve a static directory index file that is not named `index`. For example, to serve `main.html` instead of `index.html` for directory requests, set `config.static_index` to `"main"`.
+* `ActionDispatch::Static` is used to serve static assets. Disabled if `config.public_file_server.enabled` is `false`. Set `config.public_file_server.index_name` if you need to serve a static directory index file that is not named `index`. For example, to serve `main.html` instead of `index.html` for directory requests, set `config.public_file_server.index_name` to `"main"`.
 * `Rack::Lock` wraps the app in mutex so it can only be called by a single thread at a time. Only enabled when `config.cache_classes` is `false`.
 * `ActiveSupport::Cache::Strategy::LocalCache` serves as a basic memory backed cache. This cache is not thread safe and is intended only for serving as a temporary memory cache for a single thread.
 * `Rack::Runtime` sets an `X-Runtime` header, containing the time (in seconds) taken to execute the request.
@@ -1151,3 +1151,25 @@ Disallow: /
 
 To block just specific pages, it's necessary to use a more complex syntax. Learn
 it on the [official documentation](http://www.robotstxt.org/robotstxt.html).
+
+Evented File System Monitor
+---------------------------
+
+If the [listen gem](https://github.com/guard/listen) is loaded Rails uses an
+evented file system monitor to detect changes when `config.cache_classes` is
+false:
+
+```ruby
+group :development do
+  gem 'listen', '~> 3.0.4'
+end
+```
+
+Otherwise, in every request Rails walks the application tree to check if
+anything has changed.
+
+On Linux and Mac OS X no additional gems are needed, but some are required
+[for *BSD](https://github.com/guard/listen#on-bsd) and
+[for Windows](https://github.com/guard/listen#on-windows).
+
+Note that [some setups are unsupported](https://github.com/guard/listen#issues--limitations).
diff --git a/guides/source/contributing_to_ruby_on_rails.md b/guides/source/contributing_to_ruby_on_rails.md
index 53c3cbf80b..5885eb6e1c 100644
--- a/guides/source/contributing_to_ruby_on_rails.md
+++ b/guides/source/contributing_to_ruby_on_rails.md
@@ -148,6 +148,42 @@ NOTE: To help our CI servers you should add [ci skip] to your documentation comm
 
 WARNING: Docrails has a very strict policy: no code can be touched whatsoever, no matter how trivial or small the change. Only RDoc and guides can be edited via docrails. Also, CHANGELOGs should never be edited in docrails.
 
+Translating Rails Guides
+------------------------
+
+We are happy to have people volunteer to translate the Rails guides into their own language.
+If you want to translate the Rails guides in your own language, follows these steps:
+
+* Fork the project (rails/rails).
+* Add a source folder for your own language, for example: *guides/source/it-IT* for Italian.
+* Copy the contents of *guides/source* into your own language directory and translate them.
+* Do NOT translate the HTML files, as they are automatically generated.
+
+To generate the guides in HTML format cd into the *guides* direcotry then run (eg. for it-IT):
+
+```bash
+$ bundle install
+$ bundle exec rake guides:generate:html GUIDES_LANGUAGE=it-IT
+```
+
+This will generate the guides in an *output* directory.
+
+NOTE: The instructions are for Rails > 4. The Redcarpet Gem doesn't work with JRuby.
+
+Translation efforts we know about (various versions):
+
+* **Italian**: [https://github.com/rixlabs/docrails](https://github.com/rixlabs/docrails)
+* **Spanish**: [http://wiki.github.com/gramos/docrails](http://wiki.github.com/gramos/docrails)
+* **Polish**: [http://github.com/apohllo/docrails/tree/master](http://github.com/apohllo/docrails/tree/master)
+* **French** : [http://github.com/railsfrance/docrails](http://github.com/railsfrance/docrails)
+* **Czech** : [https://github.com/rubyonrails-cz/docrails/tree/czech](https://github.com/rubyonrails-cz/docrails/tree/czech)
+* **Turkish** : [https://github.com/ujk/docrails/tree/master](https://github.com/ujk/docrails/tree/master)
+* **Korean** : [https://github.com/rorlakr/rails-guides](https://github.com/rorlakr/rails-guides)
+* **Simplified Chinese** : [https://github.com/ruby-china/guides](https://github.com/ruby-china/guides)
+* **Traditional Chinese** : [https://github.com/docrails-tw/guides](https://github.com/docrails-tw/guides)
+* **Russian** : [https://github.com/morsbox/rusrails](https://github.com/morsbox/rusrails)
+* **Japanese** : [https://github.com/yasslab/railsguides.jp](https://github.com/yasslab/railsguides.jp)
+
 Contributing to the Rails Code
 ------------------------------
 
diff --git a/guides/source/debugging_rails_applications.md b/guides/source/debugging_rails_applications.md
index a05abb61d6..5424313b33 100644
--- a/guides/source/debugging_rails_applications.md
+++ b/guides/source/debugging_rails_applications.md
@@ -862,8 +862,8 @@ such as Valgrind.
 
 ### Valgrind
 
-[Valgrind](http://valgrind.org/) is a Linux-only application for detecting
-C-based memory leaks and race conditions.
+[Valgrind](http://valgrind.org/) is an application for detecting C-based memory
+leaks and race conditions.
 
 There are Valgrind tools that can automatically detect many memory management
 and threading bugs, and profile your programs in detail. For example, if a C
diff --git a/guides/source/engines.md b/guides/source/engines.md
index f961b799f1..359796b1ff 100644
--- a/guides/source/engines.md
+++ b/guides/source/engines.md
@@ -239,6 +239,27 @@ NOTE: The `ApplicationController` class inside an engine is named just like a
 Rails application in order to make it easier for you to convert your
 applications into engines.
 
+NOTE: Because of the way that Ruby does constant lookup you may run into a situation
+where your engine controller is inheriting from the main application controller and
+not your engine's application controller. Ruby is able to resolve the `ApplicationController` constant, and therefore the autoloading mechanism is not triggered. See the section [When Constants Aren't Missed](autoloading_and_reloading_constants.html#when-constants-aren-t-missed) of the [Autoloading and Reloading Constants](autoloading_and_reloading_constants.html) guide for further details. The best way to prevent this from
+happening is to use `require_dependency` to ensure that the engine's application
+controller is loaded. For example:
+
+``` ruby
+# app/controllers/blorgh/articles_controller.rb:
+require_dependency "blorgh/application_controller"
+
+module Blorgh
+  class ArticlesController < ApplicationController
+    ...
+  end
+end
+```
+
+WARNING: Don't use `require` because it will break the automatic reloading of classes
+in the development environment - using `require_dependency` ensures that classes are
+loaded and unloaded in the correct manner.
+
 Lastly, the `app/views` directory contains a `layouts` folder, which contains a
 file at `blorgh/application.html.erb`. This file allows you to specify a layout
 for the engine. If this engine is to be used as a stand-alone engine, then you
diff --git a/guides/source/form_helpers.md b/guides/source/form_helpers.md
index 0a6e2e5dba..93bb51557a 100644
--- a/guides/source/form_helpers.md
+++ b/guides/source/form_helpers.md
@@ -657,7 +657,7 @@ NOTE: If the user has not selected a file the corresponding parameter will be an
 
 ### Dealing with Ajax
 
-Unlike other forms making an asynchronous file upload form is not as simple as providing `form_for` with `remote: true`. With an Ajax form the serialization is done by JavaScript running inside the browser and since JavaScript cannot read files from your hard drive the file cannot be uploaded. The most common workaround is to use an invisible iframe that serves as the target for the form submission.
+Unlike other forms, making an asynchronous file upload form is not as simple as providing `form_for` with `remote: true`. With an Ajax form the serialization is done by JavaScript running inside the browser and since JavaScript cannot read files from your hard drive the file cannot be uploaded. The most common workaround is to use an invisible iframe that serves as the target for the form submission.
 
 Customizing Form Builders
 -------------------------
diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index 87d2fafaf3..8381636196 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -805,6 +805,8 @@ en:
 
 Then `User.human_attribute_name("gender.female")` will return "Female".
 
+NOTE: If you are using a class which includes `ActiveModel` and does not inherit from `ActiveRecord::Base`, replace `activerecord` with `activemodel` in the above key paths.
+
 #### Error Message Scopes
 
 Active Record validation error messages can also be translated easily. Active Record gives you a couple of namespaces where you can place your message translations in order to provide different messages and translation for certain models, attributes, and/or validations. It also transparently takes single table inheritance into account.
diff --git a/guides/source/plugins.md b/guides/source/plugins.md
index b94c26a1ae..922bbb4f73 100644
--- a/guides/source/plugins.md
+++ b/guides/source/plugins.md
@@ -294,7 +294,7 @@ Getting closer... Now we will implement the code of the `acts_as_yaffle` method
 
 module Yaffle
   module ActsAsYaffle
-   extend ActiveSupport::Concern
+    extend ActiveSupport::Concern
 
     included do
     end
diff --git a/guides/source/testing.md b/guides/source/testing.md
index 2f941a8280..3bfbf4f7ff 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -54,10 +54,12 @@ NOTE: Your tests are run under `RAILS_ENV=test`.
 
 ### Rails meets Minitest
 
-If you remember when you used the `rails generate scaffold` command from the [Getting Started with Rails](getting_started.html) guide. We created our first resource among other things it created test stubs in the `test` directory:
+If you remember when you used the `rails generate model` command from the
+[Getting Started with Rails](getting_started.html) guide. We created our first
+model among other things it created test stubs in the `test` directory:
 
 ```bash
-$ bin/rails generate scaffold article title:string body:text
+$ bin/rails generate model article title:string body:text
 ...
 create  app/models/article.rb
 create  test/models/article_test.rb
@@ -155,7 +157,7 @@ Failed assertion, no message given.
 1 tests, 1 assertions, 1 failures, 0 errors, 0 skips
 ```
 
-In the output, `F` denotes a failure. You can see the corresponding trace shown under `1)` along with the name of the failing test. The next few lines contain the stack trace followed by a message which mentions the actual value and the expected value by the assertion. The default assertion messages provide just enough information to help pinpoint the error. To make the assertion failure message more readable, every assertion provides an optional message parameter, as shown here:
+In the output, `F` denotes a failure. You can see the corresponding trace shown under `1)` along with the name of the failing test. The next few lines contain the stack trace followed by a message that mentions the actual value and the expected value by the assertion. The default assertion messages provide just enough information to help pinpoint the error. To make the assertion failure message more readable, every assertion provides an optional message parameter, as shown here:
 
 ```ruby
 test "should not save article without title" do
@@ -523,7 +525,7 @@ Model tests don't have their own superclass like `ActionMailer::TestCase` instea
 Integration Testing
 -------------------
 
-Integration tests are used to test how various parts of your application interact. They are generally used to test important work flows within your application.
+Integration tests are used to test how various parts of your application interact. They are generally used to test important workflows within your application.
 
 For creating Rails integration tests, we use the 'test/integration' directory for your application. Rails provides a generator to create an integration test skeleton for you.
 
@@ -649,14 +651,31 @@ You should test for things such as:
 * was the correct object stored in the response template?
 * was the appropriate message displayed to the user in the view?
 
-Now that we have used Rails scaffold generator for our `Article` resource, it has already created the controller code and tests. You can take look at the file `articles_controller_test.rb` in the `test/controllers` directory.
+The easiest way to see functional tests in action is to generate a controller
+scaffold:
 
-The following command will generate a controller test case with a filled up
-test for each of the seven default actions.
+```bash
+$ bin/rails generate scaffold_controller article title:string body:test
+...
+create  app/controllers/articles_controller.rb
+...
+invoke  test_unit
+create    test/controllers/articles_controller_test.rb
+...
+```
+
+This will generate the controller code and tests for an `Article` resource.
+You can take look at the file `articles_controller_test.rb` in the `test/controllers` directory.
+
+If you already have a controller and just want to generate the test scaffold code for
+each of the seven default actions, you can use the following command:
 
 ```bash
 $ bin/rails generate test_unit:scaffold article
+...
+invoke  test_unit
 create test/controllers/articles_controller_test.rb
+...
 ```
 
 Let me take you through one such test, `test_should_get_index` from the file `articles_controller_test.rb`.
@@ -1232,3 +1251,24 @@ class ProductTest < ActiveJob::TestCase
   end
 end
 ```
+
+Testing Time-Dependent Code
+---------------------------
+
+Rails provides inbuilt helper methods that enable you to assert that your time-sensitve code works as expected.
+
+Here is an example using the [`travel_to`](http://api.rubyonrails.org/classes/ActiveSupport/Testing/TimeHelpers.html#method-i-travel_to) helper:
+
+```ruby
+# Lets say that a user is eligible for gifting a month after they register.
+user = User.create(name: 'Gaurish', activation_date: Date.new(2004, 10, 24))
+assert_not user.applicable_for_gifting?
+travel_to Date.new(2004, 11, 24) do
+  assert_equal Date.new(2004, 10, 24), user.activation_date # inside the travel_to block `Date.current` is mocked
+  assert user.applicable_for_gifting?
+end
+assert_equal Date.new(2004, 10, 24), user.activation_date # The change was visible only inside the `travel_to` block.
+```
+
+Please see [`ActiveSupport::TimeHelpers` API Documentation](http://api.rubyonrails.org/classes/ActiveSupport/Testing/TimeHelpers.html)
+for in-depth information about the available time helpers.