Merge branch 'master' into clear_all_environments_log_by_default

66 files changed, 580 insertions, 500 deletions

diff --git a/railties/lib/rails.rb b/railties/lib/rails.rb
index 5d862e3fec..ee48043a50 100644
--- a/railties/lib/rails.rb
+++ b/railties/lib/rails.rb
@@ -53,7 +53,7 @@ module Rails
     end
 
     # Returns a Pathname object of the current Rails project,
-    # otherwise it returns nil if there is no project:
+    # otherwise it returns +nil+ if there is no project:
     #
     #   Rails.root
     #     # => #<Pathname:/Users/someuser/some/path/project>
@@ -100,7 +100,7 @@ module Rails
     end
 
     # Returns a Pathname object of the public folder of the current
-    # Rails project, otherwise it returns nil if there is no project:
+    # Rails project, otherwise it returns +nil+ if there is no project:
     #
     #   Rails.public_path
     #     # => #<Pathname:/Users/someuser/some/path/project/public>
diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index b01196e3ed..f96432c89f 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -274,7 +274,7 @@ module Rails
     # Sends the initializers to the +initializer+ method defined in the
     # Rails::Initializable module. Each Rails::Application class has its own
     # set of initializers, as defined by the Initializable module.
-    def initializer(name, opts={}, &block)
+    def initializer(name, opts = {}, &block)
       self.class.initializer(name, opts, &block)
     end
 
@@ -347,7 +347,7 @@ module Rails
 
     # Initialize the application passing the given group. By default, the
     # group is :default
-    def initialize!(group=:default) #:nodoc:
+    def initialize!(group = :default) #:nodoc:
       raise "Application has been already initialized." if @initialized
       run_initializers(group, self)
       @initialized = true
@@ -394,8 +394,8 @@ module Rails
           shared_secrets = all_secrets["shared"]
           env_secrets    = all_secrets[Rails.env]
 
-          secrets.merge!(shared_secrets.symbolize_keys) if shared_secrets
-          secrets.merge!(env_secrets.symbolize_keys) if env_secrets
+          secrets.merge!(shared_secrets.deep_symbolize_keys) if shared_secrets
+          secrets.merge!(env_secrets.deep_symbolize_keys) if env_secrets
         end
 
         # Fallback to config.secret_key_base if secrets.secret_key_base isn't set
diff --git a/railties/lib/rails/application_controller.rb b/railties/lib/rails/application_controller.rb
index f8394b8e0a..a98e51fd28 100644
--- a/railties/lib/rails/application_controller.rb
+++ b/railties/lib/rails/application_controller.rb
@@ -2,7 +2,7 @@ class Rails::ApplicationController < ActionController::Base # :nodoc:
   self.view_paths = File.expand_path("../templates", __FILE__)
   layout "application"
 
-  protected
+  private
 
     def require_local!
       unless local_request?
diff --git a/railties/lib/rails/code_statistics.rb b/railties/lib/rails/code_statistics.rb
index b3d88147a5..9c4bd16aad 100644
--- a/railties/lib/rails/code_statistics.rb
+++ b/railties/lib/rails/code_statistics.rb
@@ -106,7 +106,7 @@ class CodeStatistics #:nodoc:
       code  = calculate_code
       tests = calculate_tests
 
-      puts "  Code LOC: #{code}     Test LOC: #{tests}     Code to Test Ratio: 1:#{sprintf("%.1f", tests.to_f/code)}"
+      puts "  Code LOC: #{code}     Test LOC: #{tests}     Code to Test Ratio: 1:#{sprintf("%.1f", tests.to_f / code)}"
       puts ""
     end
 end
diff --git a/railties/lib/rails/command.rb b/railties/lib/rails/command.rb
index 6065e78fd1..ddb953543f 100644
--- a/railties/lib/rails/command.rb
+++ b/railties/lib/rails/command.rb
@@ -82,16 +82,16 @@ module Rails
         [[ "rails", rails ]] + groups.sort.to_a
       end
 
-      protected
-        def command_type
+      private
+        def command_type # :doc:
           @command_type ||= "command"
         end
 
-        def lookup_paths
+        def lookup_paths # :doc:
           @lookup_paths ||= %w( rails/commands commands )
         end
 
-        def file_lookup_paths
+        def file_lookup_paths # :doc:
           @file_lookup_paths ||= [ "{#{lookup_paths.join(',')}}", "**", "*_command.rb" ]
         end
     end
diff --git a/railties/lib/rails/command/behavior.rb b/railties/lib/rails/command/behavior.rb
index ce994746a4..4a92f72f16 100644
--- a/railties/lib/rails/command/behavior.rb
+++ b/railties/lib/rails/command/behavior.rb
@@ -16,13 +16,13 @@ module Rails
           @subclasses ||= []
         end
 
-        protected
+        private
 
           # This code is based directly on the Text gem implementation.
           # Copyright (c) 2006-2013 Paul Battley, Michael Neumann, Tim Fletcher.
           #
           # Returns a value representing the "cost" of transforming str1 into str2.
-          def levenshtein_distance(str1, str2)
+          def levenshtein_distance(str1, str2) # :doc:
             s = str1
             t = str2
             n = s.length
@@ -38,12 +38,12 @@ module Rails
             str2_codepoint_enumerable = str2.each_codepoint
 
             str1.each_codepoint.with_index do |char1, i|
-              e = i+1
+              e = i + 1
 
               str2_codepoint_enumerable.with_index do |char2, j|
                 cost = (char1 == char2) ? 0 : 1
                 x = [
-                     d[j+1] + 1, # insertion
+                     d[j + 1] + 1, # insertion
                      e + 1,      # deletion
                      d[j] + cost # substitution
                     ].min
@@ -58,7 +58,7 @@ module Rails
           end
 
           # Prints a list of generators.
-          def print_list(base, namespaces) #:nodoc:
+          def print_list(base, namespaces)
             return if namespaces.empty?
             puts "#{base.camelize}:"
 
@@ -71,7 +71,7 @@ module Rails
 
           # Receives namespaces in an array and tries to find matching generators
           # in the load path.
-          def lookup(namespaces) #:nodoc:
+          def lookup(namespaces)
             paths = namespaces_to_paths(namespaces)
 
             paths.each do |raw_path|
@@ -91,7 +91,7 @@ module Rails
           end
 
           # This will try to load any command in the load path to show in help.
-          def lookup! #:nodoc:
+          def lookup!
             $LOAD_PATH.each do |base|
               Dir[File.join(base, *file_lookup_paths)].each do |path|
                 begin
@@ -107,7 +107,7 @@ module Rails
           # Convert namespaces to paths by replacing ":" for "/" and adding
           # an extra lookup. For example, "rails:model" should be searched
           # in both: "rails/model/model_generator" and "rails/model_generator".
-          def namespaces_to_paths(namespaces) #:nodoc:
+          def namespaces_to_paths(namespaces)
             paths = []
             namespaces.each do |namespace|
               pieces = namespace.split(":")
diff --git a/railties/lib/rails/commands/application/application_command.rb b/railties/lib/rails/commands/application/application_command.rb
index 7e3a2b011d..7675d3b3d1 100644
--- a/railties/lib/rails/commands/application/application_command.rb
+++ b/railties/lib/rails/commands/application/application_command.rb
@@ -13,7 +13,7 @@ module Rails
   end
 
   module Command
-    class ApplicationCommand < Base
+    class ApplicationCommand < Base # :nodoc:
       hide_command!
 
       def help
diff --git a/railties/lib/rails/commands/console/console_command.rb b/railties/lib/rails/commands/console/console_command.rb
index 617066f575..62e3aa19df 100644
--- a/railties/lib/rails/commands/console/console_command.rb
+++ b/railties/lib/rails/commands/console/console_command.rb
@@ -64,7 +64,7 @@ module Rails
   end
 
   module Command
-    class ConsoleCommand < Base
+    class ConsoleCommand < Base # :nodoc:
       include EnvironmentArgument
 
       class_option :sandbox, aliases: "-s", type: :boolean, default: false,
diff --git a/railties/lib/rails/commands/dbconsole/dbconsole_command.rb b/railties/lib/rails/commands/dbconsole/dbconsole_command.rb
index d3c80da89b..588fb06b15 100644
--- a/railties/lib/rails/commands/dbconsole/dbconsole_command.rb
+++ b/railties/lib/rails/commands/dbconsole/dbconsole_command.rb
@@ -1,6 +1,3 @@
-require "erb"
-require "yaml"
-
 require "rails/command/environment_argument"
 
 module Rails
@@ -102,14 +99,14 @@ module Rails
       Rails.respond_to?(:env) ? Rails.env : Rails::Command.environment
     end
 
-    protected
-      def configurations
+    private
+      def configurations # :doc:
         require APP_PATH
         ActiveRecord::Base.configurations = Rails.application.config.database_configuration
         ActiveRecord::Base.configurations
       end
 
-      def find_cmd_and_exec(commands, *args)
+      def find_cmd_and_exec(commands, *args) # :doc:
         commands = Array(commands)
 
         dirs_on_path = ENV["PATH"].to_s.split(File::PATH_SEPARATOR)
@@ -134,7 +131,7 @@ module Rails
   end
 
   module Command
-    class DbconsoleCommand < Base
+    class DbconsoleCommand < Base # :nodoc:
       include EnvironmentArgument
 
       class_option :include_password, aliases: "-p", type: :boolean,
diff --git a/railties/lib/rails/commands/destroy/destroy_command.rb b/railties/lib/rails/commands/destroy/destroy_command.rb
index 5e6b7f9371..5b552b2070 100644
--- a/railties/lib/rails/commands/destroy/destroy_command.rb
+++ b/railties/lib/rails/commands/destroy/destroy_command.rb
@@ -2,8 +2,8 @@ require "rails/generators"
 
 module Rails
   module Command
-    class DestroyCommand < Base
-      def help # :nodoc:
+    class DestroyCommand < Base # :nodoc:
+      def help
         Rails::Generators.help self.class.command_name
       end
 
diff --git a/railties/lib/rails/commands/generate/generate_command.rb b/railties/lib/rails/commands/generate/generate_command.rb
index b381ca85b9..aa8dab71b0 100644
--- a/railties/lib/rails/commands/generate/generate_command.rb
+++ b/railties/lib/rails/commands/generate/generate_command.rb
@@ -2,8 +2,8 @@ require "rails/generators"
 
 module Rails
   module Command
-    class GenerateCommand < Base
-      def help # :nodoc:
+    class GenerateCommand < Base # :nodoc:
+      def help
         Rails::Generators.help self.class.command_name
       end
 
@@ -14,6 +14,8 @@ module Rails
         require_application_and_environment!
         load_generators
 
+        ARGV.shift
+
         Rails::Generators.invoke generator, args, behavior: :invoke, destination_root: Rails::Command.root
       end
     end
diff --git a/railties/lib/rails/commands/help/help_command.rb b/railties/lib/rails/commands/help/help_command.rb
index 5bcc4c8eee..90d37217fc 100644
--- a/railties/lib/rails/commands/help/help_command.rb
+++ b/railties/lib/rails/commands/help/help_command.rb
@@ -1,6 +1,6 @@
 module Rails
   module Command
-    class HelpCommand < Base
+    class HelpCommand < Base # :nodoc:
       hide_command!
 
       def help(*)
diff --git a/railties/lib/rails/commands/new/new_command.rb b/railties/lib/rails/commands/new/new_command.rb
index 13eedfc479..74d1fa5021 100644
--- a/railties/lib/rails/commands/new/new_command.rb
+++ b/railties/lib/rails/commands/new/new_command.rb
@@ -1,6 +1,6 @@
 module Rails
   module Command
-    class NewCommand < Base
+    class NewCommand < Base # :nodoc:
       def help
         Rails::Command.invoke :application, [ "--help" ]
       end
diff --git a/railties/lib/rails/commands/plugin/plugin_command.rb b/railties/lib/rails/commands/plugin/plugin_command.rb
index d6d9fe4400..b40ab006af 100644
--- a/railties/lib/rails/commands/plugin/plugin_command.rb
+++ b/railties/lib/rails/commands/plugin/plugin_command.rb
@@ -1,6 +1,6 @@
 module Rails
   module Command
-    class PluginCommand < Base
+    class PluginCommand < Base # :nodoc:
       hide_command!
 
       def help
@@ -11,7 +11,7 @@ module Rails
         "#{executable} new [options]"
       end
 
-      class_option :rc, type: :boolean, default: File.join("~", ".railsrc"),
+      class_option :rc, type: :string, default: File.join("~", ".railsrc"),
         desc: "Initialize the plugin command with previous defaults. Uses .railsrc in your home directory by default."
 
       class_option :no_rc, desc: "Skip evaluating .railsrc."
diff --git a/railties/lib/rails/commands/rake/rake_command.rb b/railties/lib/rails/commands/rake/rake_command.rb
index a43c884170..f03dc81117 100644
--- a/railties/lib/rails/commands/rake/rake_command.rb
+++ b/railties/lib/rails/commands/rake/rake_command.rb
@@ -1,6 +1,6 @@
 module Rails
   module Command
-    class RakeCommand < Base
+    class RakeCommand < Base # :nodoc:
       extend Rails::Command::Actions
 
       namespace "rake"
diff --git a/railties/lib/rails/commands/runner/USAGE b/railties/lib/rails/commands/runner/USAGE
index dc47a35ff3..b2a6e8493d 100644
--- a/railties/lib/rails/commands/runner/USAGE
+++ b/railties/lib/rails/commands/runner/USAGE
@@ -8,7 +8,7 @@ Run the Ruby file located at `path/to/filename.rb` after loading the app:
 
   <%= executable %> path/to/filename.rb
 
-<% if RbConfig::CONFIG['host_os'] !~ /mswin|mingw/ %>
+<% unless Gem.win_platform? %>
 You can also use the runner command as a shebang line for your executables:
 
   #!/usr/bin/env <%= File.expand_path(executable) %>
diff --git a/railties/lib/rails/commands/runner/runner_command.rb b/railties/lib/rails/commands/runner/runner_command.rb
index 8db6da8759..4989a7837d 100644
--- a/railties/lib/rails/commands/runner/runner_command.rb
+++ b/railties/lib/rails/commands/runner/runner_command.rb
@@ -1,6 +1,6 @@
 module Rails
   module Command
-    class RunnerCommand < Base
+    class RunnerCommand < Base # :nodoc:
       class_option :environment, aliases: "-e", type: :string,
         default: Rails::Command.environment.dup,
         desc: "The environment for the runner to operate under (test/development/production)"
@@ -14,7 +14,7 @@ module Rails
         "#{super} [<'Some.ruby(code)'> | <filename.rb>]"
       end
 
-      def perform(code_or_file = nil)
+      def perform(code_or_file = nil, *file_argv)
         unless code_or_file
           help
           exit 1
@@ -27,6 +27,7 @@ module Rails
 
         if File.exist?(code_or_file)
           $0 = code_or_file
+          ARGV.replace(file_argv)
           Kernel.load code_or_file
         else
           begin
diff --git a/railties/lib/rails/commands/server/server_command.rb b/railties/lib/rails/commands/server/server_command.rb
index 14cf72f483..e9538b804c 100644
--- a/railties/lib/rails/commands/server/server_command.rb
+++ b/railties/lib/rails/commands/server/server_command.rb
@@ -139,8 +139,8 @@ module Rails
   end
 
   module Command
-    class ServerCommand < Base
-      def help # :nodoc:
+    class ServerCommand < Base # :nodoc:
+      def help
         puts Rails::Server::Options.new.option_parser(Hash.new)
       end
 
diff --git a/railties/lib/rails/commands/test/test_command.rb b/railties/lib/rails/commands/test/test_command.rb
index 1b2e3af9cc..7bf8f61137 100644
--- a/railties/lib/rails/commands/test/test_command.rb
+++ b/railties/lib/rails/commands/test/test_command.rb
@@ -3,8 +3,8 @@ require "rails/test_unit/minitest_plugin"
 
 module Rails
   module Command
-    class TestCommand < Base
-      def help # :nodoc:
+    class TestCommand < Base # :nodoc:
+      def help
         perform # Hand over help printing to minitest.
       end
 
diff --git a/railties/lib/rails/commands/version/version_command.rb b/railties/lib/rails/commands/version/version_command.rb
index 4f3fbfca1b..ac745594ee 100644
--- a/railties/lib/rails/commands/version/version_command.rb
+++ b/railties/lib/rails/commands/version/version_command.rb
@@ -1,6 +1,6 @@
 module Rails
   module Command
-    class VersionCommand < Base
+    class VersionCommand < Base # :nodoc:
       def perform
         Rails::Command.invoke :application, [ "--version" ]
       end
diff --git a/railties/lib/rails/configuration.rb b/railties/lib/rails/configuration.rb
index 7dfab969e8..fc7d4909f6 100644
--- a/railties/lib/rails/configuration.rb
+++ b/railties/lib/rails/configuration.rb
@@ -91,8 +91,8 @@ module Rails
       attr_reader :hidden_namespaces
 
       def initialize
-        @aliases = Hash.new { |h,k| h[k] = {} }
-        @options = Hash.new { |h,k| h[k] = {} }
+        @aliases = Hash.new { |h, k| h[k] = {} }
+        @options = Hash.new { |h, k| h[k] = {} }
         @fallbacks = {}
         @templates = []
         @colorize_logging = true
diff --git a/railties/lib/rails/console/app.rb b/railties/lib/rails/console/app.rb
index 541d5e3dad..affadc8e09 100644
--- a/railties/lib/rails/console/app.rb
+++ b/railties/lib/rails/console/app.rb
@@ -5,7 +5,7 @@ module Rails
   module ConsoleMethods
     # reference the global "app" instance, created on demand. To recreate the
     # instance, pass a non-false value as the parameter.
-    def app(create=false)
+    def app(create = false)
       @app_integration_instance = nil if create
       @app_integration_instance ||= new_session do |sess|
         sess.host! "www.example.com"
@@ -27,7 +27,7 @@ module Rails
     end
 
     # reloads the environment
-    def reload!(print=true)
+    def reload!(print = true)
       puts "Reloading..." if print
       Rails.application.reloader.reload!
       true
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 90e7c04d7c..2dd1fb3273 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -436,7 +436,7 @@ module Rails
 
     # Load console and invoke the registered hooks.
     # Check <tt>Rails::Railtie.console</tt> for more info.
-    def load_console(app=self)
+    def load_console(app = self)
       require "rails/console/app"
       require "rails/console/helpers"
       run_console_blocks(app)
@@ -445,14 +445,14 @@ module Rails
 
     # Load Rails runner and invoke the registered hooks.
     # Check <tt>Rails::Railtie.runner</tt> for more info.
-    def load_runner(app=self)
+    def load_runner(app = self)
       run_runner_blocks(app)
       self
     end
 
     # Load Rake, railties tasks and invoke the registered hooks.
     # Check <tt>Rails::Railtie.rake_tasks</tt> for more info.
-    def load_tasks(app=self)
+    def load_tasks(app = self)
       require "rake"
       run_tasks_blocks(app)
       self
@@ -460,7 +460,7 @@ module Rails
 
     # Load Rails generators and invoke the registered hooks.
     # Check <tt>Rails::Railtie.generators</tt> for more info.
-    def load_generators(app=self)
+    def load_generators(app = self)
       require "rails/generators"
       run_generators_blocks(app)
       Rails::Generators.configure!(app.config.generators)
@@ -643,22 +643,24 @@ module Rails
 
     protected
 
-      def load_config_initializer(initializer)
-        ActiveSupport::Notifications.instrument("load_config_initializer.railties", initializer: initializer) do
-          load(initializer)
-        end
-      end
-
       def run_tasks_blocks(*) #:nodoc:
         super
         paths["lib/tasks"].existent.sort.each { |ext| load(ext) }
       end
 
-      def has_migrations? #:nodoc:
+    private
+
+      def load_config_initializer(initializer) # :doc:
+        ActiveSupport::Notifications.instrument("load_config_initializer.railties", initializer: initializer) do
+          load(initializer)
+        end
+      end
+
+      def has_migrations?
         paths["db/migrate"].existent.any?
       end
 
-      def self.find_root_with_flag(flag, root_path, default=nil) #:nodoc:
+      def self.find_root_with_flag(flag, root_path, default = nil) #:nodoc:
 
         while root_path && File.directory?(root_path) && !File.exist?("#{root_path}/#{flag}")
           parent = File.dirname(root_path)
@@ -671,24 +673,22 @@ module Rails
         Pathname.new File.realpath root
       end
 
-      def default_middleware_stack #:nodoc:
+      def default_middleware_stack
         ActionDispatch::MiddlewareStack.new
       end
 
-      def _all_autoload_once_paths #:nodoc:
+      def _all_autoload_once_paths
         config.autoload_once_paths
       end
 
-      def _all_autoload_paths #:nodoc:
+      def _all_autoload_paths
         @_all_autoload_paths ||= (config.autoload_paths + config.eager_load_paths + config.autoload_once_paths).uniq
       end
 
-      def _all_load_paths #:nodoc:
+      def _all_load_paths
         @_all_load_paths ||= (config.paths.load_paths + _all_autoload_paths).uniq
       end
 
-    private
-
       def build_request(env)
         env.merge!(env_config)
         req = ActionDispatch::Request.new env
diff --git a/railties/lib/rails/engine/configuration.rb b/railties/lib/rails/engine/configuration.rb
index 147b904679..0c40173c38 100644
--- a/railties/lib/rails/engine/configuration.rb
+++ b/railties/lib/rails/engine/configuration.rb
@@ -7,7 +7,7 @@ module Rails
       attr_accessor :middleware
       attr_writer :eager_load_paths, :autoload_once_paths, :autoload_paths
 
-      def initialize(root=nil)
+      def initialize(root = nil)
         super()
         @root = root
         @generators = app_generators.dup
diff --git a/railties/lib/rails/generators.rb b/railties/lib/rails/generators.rb
index dd16b44786..e1980a42ad 100644
--- a/railties/lib/rails/generators.rb
+++ b/railties/lib/rails/generators.rb
@@ -67,246 +67,247 @@ module Rails
       }
     }
 
-    def self.configure!(config) #:nodoc:
-      api_only! if config.api_only
-      no_color! unless config.colorize_logging
-      aliases.deep_merge! config.aliases
-      options.deep_merge! config.options
-      fallbacks.merge! config.fallbacks
-      templates_path.concat config.templates
-      templates_path.uniq!
-      hide_namespaces(*config.hidden_namespaces)
-    end
+    class << self
+      def configure!(config) #:nodoc:
+        api_only! if config.api_only
+        no_color! unless config.colorize_logging
+        aliases.deep_merge! config.aliases
+        options.deep_merge! config.options
+        fallbacks.merge! config.fallbacks
+        templates_path.concat config.templates
+        templates_path.uniq!
+        hide_namespaces(*config.hidden_namespaces)
+      end
 
-    def self.templates_path #:nodoc:
-      @templates_path ||= []
-    end
+      def templates_path #:nodoc:
+        @templates_path ||= []
+      end
 
-    def self.aliases #:nodoc:
-      @aliases ||= DEFAULT_ALIASES.dup
-    end
+      def aliases #:nodoc:
+        @aliases ||= DEFAULT_ALIASES.dup
+      end
 
-    def self.options #:nodoc:
-      @options ||= DEFAULT_OPTIONS.dup
-    end
+      def options #:nodoc:
+        @options ||= DEFAULT_OPTIONS.dup
+      end
 
-    # Hold configured generators fallbacks. If a plugin developer wants a
-    # generator group to fallback to another group in case of missing generators,
-    # they can add a fallback.
-    #
-    # For example, shoulda is considered a test_framework and is an extension
-    # of test_unit. However, most part of shoulda generators are similar to
-    # test_unit ones.
-    #
-    # Shoulda then can tell generators to search for test_unit generators when
-    # some of them are not available by adding a fallback:
-    #
-    #   Rails::Generators.fallbacks[:shoulda] = :test_unit
-    def self.fallbacks
-      @fallbacks ||= {}
-    end
+      # Hold configured generators fallbacks. If a plugin developer wants a
+      # generator group to fallback to another group in case of missing generators,
+      # they can add a fallback.
+      #
+      # For example, shoulda is considered a test_framework and is an extension
+      # of test_unit. However, most part of shoulda generators are similar to
+      # test_unit ones.
+      #
+      # Shoulda then can tell generators to search for test_unit generators when
+      # some of them are not available by adding a fallback:
+      #
+      #   Rails::Generators.fallbacks[:shoulda] = :test_unit
+      def fallbacks
+        @fallbacks ||= {}
+      end
 
-    # Configure generators for API only applications. It basically hides
-    # everything that is usually browser related, such as assets and session
-    # migration generators, and completely disable helpers and assets
-    # so generators such as scaffold won't create them.
-    def self.api_only!
-      hide_namespaces "assets", "helper", "css", "js"
-
-      options[:rails].merge!(
-        api: true,
-        assets: false,
-        helper: false,
-        template_engine: nil
-      )
-
-      if ARGV.first == "mailer"
-        options[:rails].merge!(template_engine: :erb)
+      # Configure generators for API only applications. It basically hides
+      # everything that is usually browser related, such as assets and session
+      # migration generators, and completely disable helpers and assets
+      # so generators such as scaffold won't create them.
+      def api_only!
+        hide_namespaces "assets", "helper", "css", "js"
+
+        options[:rails].merge!(
+          api: true,
+          assets: false,
+          helper: false,
+          template_engine: nil
+        )
+
+        if ARGV.first == "mailer"
+          options[:rails].merge!(template_engine: :erb)
+        end
       end
-    end
 
-    # Remove the color from output.
-    def self.no_color!
-      Thor::Base.shell = Thor::Shell::Basic
-    end
+      # Remove the color from output.
+      def no_color!
+        Thor::Base.shell = Thor::Shell::Basic
+      end
 
-    # Returns an array of generator namespaces that are hidden.
-    # Generator namespaces may be hidden for a variety of reasons.
-    # Some are aliased such as "rails:migration" and can be
-    # invoked with the shorter "migration", others are private to other generators
-    # such as "css:scaffold".
-    def self.hidden_namespaces
-      @hidden_namespaces ||= begin
-        orm      = options[:rails][:orm]
-        test     = options[:rails][:test_framework]
-        template = options[:rails][:template_engine]
-        css      = options[:rails][:stylesheet_engine]
-
-        [
-          "rails",
-          "resource_route",
-          "#{orm}:migration",
-          "#{orm}:model",
-          "#{test}:controller",
-          "#{test}:helper",
-          "#{test}:integration",
-          "#{test}:mailer",
-          "#{test}:model",
-          "#{test}:scaffold",
-          "#{test}:view",
-          "#{test}:job",
-          "#{template}:controller",
-          "#{template}:scaffold",
-          "#{template}:mailer",
-          "#{css}:scaffold",
-          "#{css}:assets",
-          "css:assets",
-          "css:scaffold"
-        ]
+      # Returns an array of generator namespaces that are hidden.
+      # Generator namespaces may be hidden for a variety of reasons.
+      # Some are aliased such as "rails:migration" and can be
+      # invoked with the shorter "migration", others are private to other generators
+      # such as "css:scaffold".
+      def hidden_namespaces
+        @hidden_namespaces ||= begin
+          orm      = options[:rails][:orm]
+          test     = options[:rails][:test_framework]
+          template = options[:rails][:template_engine]
+          css      = options[:rails][:stylesheet_engine]
+
+          [
+            "rails",
+            "resource_route",
+            "#{orm}:migration",
+            "#{orm}:model",
+            "#{test}:controller",
+            "#{test}:helper",
+            "#{test}:integration",
+            "#{test}:mailer",
+            "#{test}:model",
+            "#{test}:scaffold",
+            "#{test}:view",
+            "#{test}:job",
+            "#{template}:controller",
+            "#{template}:scaffold",
+            "#{template}:mailer",
+            "#{css}:scaffold",
+            "#{css}:assets",
+            "css:assets",
+            "css:scaffold"
+          ]
+        end
       end
-    end
 
-    class << self
       def hide_namespaces(*namespaces)
         hidden_namespaces.concat(namespaces)
       end
       alias hide_namespace hide_namespaces
-    end
 
-    # Show help message with available generators.
-    def self.help(command = "generate")
-      puts "Usage: rails #{command} GENERATOR [args] [options]"
-      puts
-      puts "General options:"
-      puts "  -h, [--help]     # Print generator's options and usage"
-      puts "  -p, [--pretend]  # Run but do not make any changes"
-      puts "  -f, [--force]    # Overwrite files that already exist"
-      puts "  -s, [--skip]     # Skip files that already exist"
-      puts "  -q, [--quiet]    # Suppress status output"
-      puts
-      puts "Please choose a generator below."
-      puts
-
-      print_generators
-    end
-
-    def self.public_namespaces
-      lookup!
-      subclasses.map(&:namespace)
-    end
-
-    def self.print_generators
-      sorted_groups.each { |b, n| print_list(b, n) }
-    end
+      # Show help message with available generators.
+      def help(command = "generate")
+        puts "Usage: rails #{command} GENERATOR [args] [options]"
+        puts
+        puts "General options:"
+        puts "  -h, [--help]     # Print generator's options and usage"
+        puts "  -p, [--pretend]  # Run but do not make any changes"
+        puts "  -f, [--force]    # Overwrite files that already exist"
+        puts "  -s, [--skip]     # Skip files that already exist"
+        puts "  -q, [--quiet]    # Suppress status output"
+        puts
+        puts "Please choose a generator below."
+        puts
+
+        print_generators
+      end
 
-    def self.sorted_groups
-      namespaces = public_namespaces
-      namespaces.sort!
+      def public_namespaces
+        lookup!
+        subclasses.map(&:namespace)
+      end
 
-      groups = Hash.new { |h,k| h[k] = [] }
-      namespaces.each do |namespace|
-        base = namespace.split(":").first
-        groups[base] << namespace
+      def print_generators
+        sorted_groups.each { |b, n| print_list(b, n) }
       end
 
-      rails = groups.delete("rails")
-      rails.map! { |n| n.sub(/^rails:/, "") }
-      rails.delete("app")
-      rails.delete("plugin")
+      def sorted_groups
+        namespaces = public_namespaces
+        namespaces.sort!
 
-      hidden_namespaces.each { |n| groups.delete(n.to_s) }
+        groups = Hash.new { |h, k| h[k] = [] }
+        namespaces.each do |namespace|
+          base = namespace.split(":").first
+          groups[base] << namespace
+        end
 
-      [[ "rails", rails ]] + groups.sort.to_a
-    end
+        rails = groups.delete("rails")
+        rails.map! { |n| n.sub(/^rails:/, "") }
+        rails.delete("app")
+        rails.delete("plugin")
 
-    # Rails finds namespaces similar to thor, it only adds one rule:
-    #
-    # Generators names must end with "_generator.rb". This is required because Rails
-    # looks in load paths and loads the generator just before it's going to be used.
-    #
-    #   find_by_namespace :webrat, :rails, :integration
-    #
-    # Will search for the following generators:
-    #
-    #   "rails:webrat", "webrat:integration", "webrat"
-    #
-    # Notice that "rails:generators:webrat" could be loaded as well, what
-    # Rails looks for is the first and last parts of the namespace.
-    def self.find_by_namespace(name, base = nil, context = nil) #:nodoc:
-      lookups = []
-      lookups << "#{base}:#{name}"    if base
-      lookups << "#{name}:#{context}" if context
-
-      unless base || context
-        unless name.to_s.include?(?:)
-          lookups << "#{name}:#{name}"
-          lookups << "rails:#{name}"
-        end
-        lookups << "#{name}"
+        hidden_namespaces.each { |n| groups.delete(n.to_s) }
+
+        [[ "rails", rails ]] + groups.sort.to_a
       end
 
-      lookup(lookups)
+      # Rails finds namespaces similar to thor, it only adds one rule:
+      #
+      # Generators names must end with "_generator.rb". This is required because Rails
+      # looks in load paths and loads the generator just before it's going to be used.
+      #
+      #   find_by_namespace :webrat, :rails, :integration
+      #
+      # Will search for the following generators:
+      #
+      #   "rails:webrat", "webrat:integration", "webrat"
+      #
+      # Notice that "rails:generators:webrat" could be loaded as well, what
+      # Rails looks for is the first and last parts of the namespace.
+      def find_by_namespace(name, base = nil, context = nil) #:nodoc:
+        lookups = []
+        lookups << "#{base}:#{name}"    if base
+        lookups << "#{name}:#{context}" if context
+
+        unless base || context
+          unless name.to_s.include?(?:)
+            lookups << "#{name}:#{name}"
+            lookups << "rails:#{name}"
+          end
+          lookups << "#{name}"
+        end
 
-      namespaces = Hash[subclasses.map { |klass| [klass.namespace, klass] }]
-      lookups.each do |namespace|
+        lookup(lookups)
 
-        klass = namespaces[namespace]
-        return klass if klass
-      end
+        namespaces = Hash[subclasses.map { |klass| [klass.namespace, klass] }]
+        lookups.each do |namespace|
 
-      invoke_fallbacks_for(name, base) || invoke_fallbacks_for(context, name)
-    end
+          klass = namespaces[namespace]
+          return klass if klass
+        end
 
-    # Receives a namespace, arguments and the behavior to invoke the generator.
-    # It's used as the default entry point for generate, destroy and update
-    # commands.
-    def self.invoke(namespace, args=ARGV, config={})
-      names = namespace.to_s.split(":")
-      if klass = find_by_namespace(names.pop, names.any? && names.join(":"))
-        args << "--help" if args.empty? && klass.arguments.any?(&:required?)
-        klass.start(args, config)
-      else
-        options     = sorted_groups.flat_map(&:last)
-        suggestions = options.sort_by { |suggested| levenshtein_distance(namespace.to_s, suggested) }.first(3)
-        msg =  "Could not find generator '#{namespace}'. "
-        msg << "Maybe you meant #{ suggestions.map { |s| "'#{s}'" }.to_sentence(last_word_connector: " or ", locale: :en) }\n"
-        msg << "Run `rails generate --help` for more options."
-        puts msg
+        invoke_fallbacks_for(name, base) || invoke_fallbacks_for(context, name)
       end
-    end
 
-    protected
-      def self.print_list(base, namespaces)
-        namespaces = namespaces.reject { |n| hidden_namespaces.include?(n) }
-        super
+      # Receives a namespace, arguments and the behavior to invoke the generator.
+      # It's used as the default entry point for generate, destroy and update
+      # commands.
+      def invoke(namespace, args = ARGV, config = {})
+        names = namespace.to_s.split(":")
+        if klass = find_by_namespace(names.pop, names.any? && names.join(":"))
+          args << "--help" if args.empty? && klass.arguments.any?(&:required?)
+          klass.start(args, config)
+        else
+          options     = sorted_groups.flat_map(&:last)
+          suggestions = options.sort_by { |suggested| levenshtein_distance(namespace.to_s, suggested) }.first(3)
+          msg =  "Could not find generator '#{namespace}'. "
+          msg << "Maybe you meant #{ suggestions.map { |s| "'#{s}'" }.to_sentence(last_word_connector: " or ", locale: :en) }\n"
+          msg << "Run `rails generate --help` for more options."
+          puts msg
+        end
       end
 
-      # Try fallbacks for the given base.
-      def self.invoke_fallbacks_for(name, base) #:nodoc:
-        return nil unless base && fallbacks[base.to_sym]
-        invoked_fallbacks = []
-
-        Array(fallbacks[base.to_sym]).each do |fallback|
-          next if invoked_fallbacks.include?(fallback)
-          invoked_fallbacks << fallback
+      private
 
-          klass = find_by_namespace(name, fallback)
-          return klass if klass
+        def print_list(base, namespaces) # :doc:
+          namespaces = namespaces.reject { |n| hidden_namespaces.include?(n) }
+          super
         end
 
-        nil
-      end
+        # Try fallbacks for the given base.
+        def invoke_fallbacks_for(name, base)
+          return nil unless base && fallbacks[base.to_sym]
+          invoked_fallbacks = []
 
-      def self.command_type
-        @command_type ||= "generator"
-      end
+          Array(fallbacks[base.to_sym]).each do |fallback|
+            next if invoked_fallbacks.include?(fallback)
+            invoked_fallbacks << fallback
 
-      def self.lookup_paths
-        @lookup_paths ||= %w( rails/generators generators )
-      end
+            klass = find_by_namespace(name, fallback)
+            return klass if klass
+          end
 
-      def self.file_lookup_paths
-        @file_lookup_paths ||= [ "{#{lookup_paths.join(',')}}", "**", "*_generator.rb" ]
-      end
+          nil
+        end
+
+        def command_type # :doc:
+          @command_type ||= "generator"
+        end
+
+        def lookup_paths # :doc:
+          @lookup_paths ||= %w( rails/generators generators )
+        end
+
+        def file_lookup_paths # :doc:
+          @file_lookup_paths ||= [ "{#{lookup_paths.join(',')}}", "**", "*_generator.rb" ]
+        end
+    end
   end
 end
diff --git a/railties/lib/rails/generators/actions.rb b/railties/lib/rails/generators/actions.rb
index ab9dc019e2..d058d82cea 100644
--- a/railties/lib/rails/generators/actions.rb
+++ b/railties/lib/rails/generators/actions.rb
@@ -68,7 +68,7 @@ module Rails
       #   add_source "http://gems.github.com/" do
       #     gem "rspec-rails"
       #   end
-      def add_source(source, options={}, &block)
+      def add_source(source, options = {}, &block)
         log :source, source
 
         in_root do
@@ -96,7 +96,7 @@ module Rails
       #   environment(nil, env: "development") do
       #     "config.action_controller.asset_host = 'localhost:3000'"
       #   end
-      def environment(data=nil, options={})
+      def environment(data = nil, options = {})
         sentinel = /class [a-z_:]+ < Rails::Application/i
         env_file_sentinel = /Rails\.application\.configure do/
         data = yield if !data && block_given?
@@ -118,7 +118,7 @@ module Rails
       #   git :init
       #   git add: "this.file that.rb"
       #   git add: "onefile.rb", rm: "badfile.cxx"
-      def git(commands={})
+      def git(commands = {})
         if commands.is_a?(Symbol)
           run "git #{commands}"
         else
@@ -137,7 +137,7 @@ module Rails
       #   end
       #
       #   vendor("foreign.rb", "# Foreign code is fun")
-      def vendor(filename, data=nil, &block)
+      def vendor(filename, data = nil, &block)
         log :vendor, filename
         create_file("vendor/#{filename}", data, verbose: false, &block)
       end
@@ -150,7 +150,7 @@ module Rails
       #   end
       #
       #   lib("foreign.rb", "# Foreign code is fun")
-      def lib(filename, data=nil, &block)
+      def lib(filename, data = nil, &block)
         log :lib, filename
         create_file("lib/#{filename}", data, verbose: false, &block)
       end
@@ -170,7 +170,7 @@ module Rails
       #   end
       #
       #   rakefile('seed.rake', 'puts "Planting seeds"')
-      def rakefile(filename, data=nil, &block)
+      def rakefile(filename, data = nil, &block)
         log :rakefile, filename
         create_file("lib/tasks/#{filename}", data, verbose: false, &block)
       end
@@ -188,7 +188,7 @@ module Rails
       #   end
       #
       #   initializer("api.rb", "API_KEY = '123456'")
-      def initializer(filename, data=nil, &block)
+      def initializer(filename, data = nil, &block)
         log :initializer, filename
         create_file("config/initializers/#{filename}", data, verbose: false, &block)
       end
@@ -210,7 +210,7 @@ module Rails
       #   rake("db:migrate")
       #   rake("db:migrate", env: "production")
       #   rake("gems:install", sudo: true)
-      def rake(command, options={})
+      def rake(command, options = {})
         execute_command :rake, command, options
       end
 
@@ -219,7 +219,7 @@ module Rails
       #   rails("db:migrate")
       #   rails("db:migrate", env: "production")
       #   rails("gems:install", sudo: true)
-      def rails_command(command, options={})
+      def rails_command(command, options = {})
         execute_command :rails, command, options
       end
 
@@ -260,12 +260,12 @@ module Rails
         @after_bundle_callbacks << block
       end
 
-      protected
+      private
 
         # Define log for backwards compatibility. If just one argument is sent,
         # invoke say, otherwise invoke say_status. Differently from say and
         # similarly to say_status, this method respects the quiet? option given.
-        def log(*args)
+        def log(*args) # :doc:
           if args.size == 1
             say args.first.to_s unless options.quiet?
           else
@@ -276,16 +276,16 @@ module Rails
 
         # Runs the supplied command using either "rake ..." or "rails ..."
         # based on the executor parameter provided.
-        def execute_command(executor, command, options={})
+        def execute_command(executor, command, options = {}) # :doc:
           log executor, command
           env  = options[:env] || ENV["RAILS_ENV"] || "development"
-          sudo = options[:sudo] && RbConfig::CONFIG["host_os"] !~ /mswin|mingw/ ? "sudo " : ""
+          sudo = options[:sudo] && !Gem.win_platform? ? "sudo " : ""
           in_root { run("#{sudo}#{extify(executor)} #{command} RAILS_ENV=#{env}", verbose: false) }
         end
 
         # Add an extension to the given name based on the platform.
-        def extify(name)
-          if RbConfig::CONFIG["host_os"] =~ /mswin|mingw/
+        def extify(name) # :doc:
+          if Gem.win_platform?
             "#{name}.bat"
           else
             name
@@ -294,7 +294,7 @@ module Rails
 
         # Surround string with single quotes if there is no quotes.
         # Otherwise fall back to double quotes
-        def quote(value)
+        def quote(value) # :doc:
           return value.inspect unless value.is_a? String
 
           if value.include?("'")
diff --git a/railties/lib/rails/generators/actions/create_migration.rb b/railties/lib/rails/generators/actions/create_migration.rb
index 587c61fd42..f677e545e5 100644
--- a/railties/lib/rails/generators/actions/create_migration.rb
+++ b/railties/lib/rails/generators/actions/create_migration.rb
@@ -37,9 +37,9 @@ module Rails
         end
         alias :exists? :existing_migration
 
-        protected
+        private
 
-          def on_conflict_behavior
+          def on_conflict_behavior # :doc:
             options = base.options.merge(config)
             if identical?
               say_status :identical, :blue, relative_existing_migration
@@ -60,7 +60,7 @@ module Rails
             end
           end
 
-          def say_status(status, color, message = relative_destination)
+          def say_status(status, color, message = relative_destination) # :doc:
             base.shell.say_status(status, message, color) if config[:verbose]
           end
       end
diff --git a/railties/lib/rails/generators/active_model.rb b/railties/lib/rails/generators/active_model.rb
index 6183944bb0..2679d06fe4 100644
--- a/railties/lib/rails/generators/active_model.rb
+++ b/railties/lib/rails/generators/active_model.rb
@@ -39,13 +39,13 @@ module Rails
       # GET edit
       # PATCH/PUT update
       # DELETE destroy
-      def self.find(klass, params=nil)
+      def self.find(klass, params = nil)
         "#{klass}.find(#{params})"
       end
 
       # GET new
       # POST create
-      def self.build(klass, params=nil)
+      def self.build(klass, params = nil)
         if params
           "#{klass}.new(#{params})"
         else
@@ -59,7 +59,7 @@ module Rails
       end
 
       # PATCH/PUT update
-      def update(params=nil)
+      def update(params = nil)
         "#{name}.update(#{params})"
       end
 
diff --git a/railties/lib/rails/generators/app_base.rb b/railties/lib/rails/generators/app_base.rb
index 91342c592c..5c809807a1 100644
--- a/railties/lib/rails/generators/app_base.rb
+++ b/railties/lib/rails/generators/app_base.rb
@@ -30,9 +30,15 @@ module Rails
         class_option :database,           type: :string, aliases: "-d", default: "sqlite3",
                                           desc: "Preconfigure for selected database (options: #{DATABASES.join('/')})"
 
-        class_option :javascript,         type: :string, aliases: "-j", default: "jquery",
+        class_option :javascript,         type: :string, aliases: "-j",
                                           desc: "Preconfigure for selected JavaScript library"
 
+        class_option :webpack,            type: :string, default: nil,
+                                          desc: "Preconfigure for app-like JavaScript with Webpack"
+
+        class_option :skip_yarn,          type: :boolean, default: false,
+                                          desc: "Don't use Yarn for managing JavaScript dependencies"
+
         class_option :skip_gemfile,       type: :boolean, default: false,
                                           desc: "Don't create a Gemfile"
 
@@ -67,6 +73,9 @@ module Rails
         class_option :skip_listen,        type: :boolean, default: false,
                                           desc: "Don't generate configuration that depends on the listen gem"
 
+        class_option :skip_coffee,        type: :boolean, default: false,
+                                          desc: "Don't use CoffeeScript"
+
         class_option :skip_javascript,    type: :boolean, aliases: "-J", default: false,
                                           desc: "Skip JavaScript files"
 
@@ -99,9 +108,9 @@ module Rails
         convert_database_option_for_jruby
       end
 
-    protected
+    private
 
-      def gemfile_entry(name, *args)
+      def gemfile_entry(name, *args) # :doc:
         options = args.extract_options!
         version = args.first
         github = options[:github]
@@ -117,11 +126,12 @@ module Rails
         self
       end
 
-      def gemfile_entries
+      def gemfile_entries # :doc:
         [rails_gemfile_entry,
          database_gemfile_entry,
          webserver_gemfile_entry,
          assets_gemfile_entry,
+         webpacker_gemfile_entry,
          javascript_gemfile_entry,
          jbuilder_gemfile_entry,
          psych_gemfile_entry,
@@ -129,13 +139,13 @@ module Rails
          @extra_entries].flatten.find_all(&@gem_filter)
       end
 
-      def add_gem_entry_filter
+      def add_gem_entry_filter # :doc:
         @gem_filter = lambda { |next_filter, entry|
           yield(entry) && next_filter.call(entry)
         }.curry[@gem_filter]
       end
 
-      def builder
+      def builder # :doc:
         @builder ||= begin
           builder_class = get_builder_class
           builder_class.include(ActionMethods)
@@ -143,24 +153,24 @@ module Rails
         end
       end
 
-      def build(meth, *args)
+      def build(meth, *args) # :doc:
         builder.send(meth, *args) if builder.respond_to?(meth)
       end
 
-      def create_root
+      def create_root # :doc:
         valid_const?
 
         empty_directory "."
         FileUtils.cd(destination_root) unless options[:pretend]
       end
 
-      def apply_rails_template
+      def apply_rails_template # :doc:
         apply rails_template if rails_template
       rescue Thor::Error, LoadError, Errno::ENOENT => e
         raise Error, "The template [#{rails_template}] could not be loaded. Error: #{e}"
       end
 
-      def set_default_accessors!
+      def set_default_accessors! # :doc:
         self.destination_root = File.expand_path(app_path, destination_root)
         self.rails_template = \
           case options[:template]
@@ -173,32 +183,32 @@ module Rails
           end
       end
 
-      def database_gemfile_entry
+      def database_gemfile_entry # :doc:
         return [] if options[:skip_active_record]
         gem_name, gem_version = gem_for_database
         GemfileEntry.version gem_name, gem_version,
                             "Use #{options[:database]} as the database for Active Record"
       end
 
-      def webserver_gemfile_entry
+      def webserver_gemfile_entry # :doc:
         return [] if options[:skip_puma]
         comment = "Use Puma as the app server"
         GemfileEntry.new("puma", "~> 3.0", comment)
       end
 
-      def include_all_railties?
+      def include_all_railties? # :doc:
         options.values_at(:skip_active_record, :skip_action_mailer, :skip_test, :skip_sprockets, :skip_action_cable).none?
       end
 
-      def comment_if(value)
+      def comment_if(value) # :doc:
         options[value] ? "# " : ""
       end
 
-      def keeps?
+      def keeps? # :doc:
         !options[:skip_keeps]
       end
 
-      def sqlite3?
+      def sqlite3? # :doc:
         !options[:skip_active_record] && options[:database] == "sqlite3"
       end
 
@@ -309,6 +319,13 @@ module Rails
         gems
       end
 
+      def webpacker_gemfile_entry
+        return [] unless options[:webpack]
+
+        comment = "Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker"
+        GemfileEntry.github "webpacker", "rails/webpacker", nil, comment
+      end
+
       def jbuilder_gemfile_entry
         comment = "Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder"
         GemfileEntry.new "jbuilder", "~> 2.5", comment, {}, options[:api]
@@ -322,9 +339,13 @@ module Rails
         if options[:skip_javascript] || options[:skip_sprockets]
           []
         else
-          gems = [coffee_gemfile_entry, javascript_runtime_gemfile_entry]
-          gems << GemfileEntry.version("#{options[:javascript]}-rails", nil,
-                                       "Use #{options[:javascript]} as the JavaScript library")
+          gems = [javascript_runtime_gemfile_entry]
+          gems << coffee_gemfile_entry unless options[:skip_coffee]
+
+          if options[:javascript]
+            gems << GemfileEntry.version("#{options[:javascript]}-rails", nil,
+              "Use #{options[:javascript]} as the JavaScript library")
+          end
 
           unless options[:skip_turbolinks]
             gems << GemfileEntry.version("turbolinks", "~> 5",
@@ -404,6 +425,13 @@ module Rails
         bundle_command("install") if bundle_install?
       end
 
+      def run_webpack
+        if !(webpack = options[:webpack]).nil?
+          rails_command "webpacker:install"
+          rails_command "webpacker:install:#{webpack}" unless webpack == "webpack"
+        end
+      end
+
       def generate_spring_binstubs
         if bundle_install? && spring_install?
           bundle_command("exec spring binstub --all")
diff --git a/railties/lib/rails/generators/base.rb b/railties/lib/rails/generators/base.rb
index 1a0420c769..cc6ae3860f 100644
--- a/railties/lib/rails/generators/base.rb
+++ b/railties/lib/rails/generators/base.rb
@@ -20,14 +20,14 @@ module Rails
       strict_args_position!
 
       # Returns the source root for this generator using default_source_root as default.
-      def self.source_root(path=nil)
+      def self.source_root(path = nil)
         @_source_root = path if path
         @_source_root ||= default_source_root
       end
 
       # Tries to get the description from a USAGE file one folder above the source
       # root otherwise uses a default description.
-      def self.desc(description=nil)
+      def self.desc(description = nil)
         return super if description
 
         @desc ||= if usage_path
@@ -40,7 +40,7 @@ module Rails
       # Convenience method to get the namespace from the class name. It's the
       # same as Thor default except that the Generator at the end of the class
       # is removed.
-      def self.namespace(name=nil)
+      def self.namespace(name = nil)
         return super if name
         @namespace ||= super.sub(/_generator$/, "").sub(/:generators:/, ":")
       end
@@ -195,7 +195,7 @@ module Rails
       end
 
       # Make class option aware of Rails::Generators.options and Rails::Generators.aliases.
-      def self.class_option(name, options={}) #:nodoc:
+      def self.class_option(name, options = {}) #:nodoc:
         options[:desc]    = "Indicates when to generate #{name.to_s.humanize.downcase}" unless options.key?(:desc)
         options[:aliases] = default_aliases_for_option(name, options)
         options[:default] = default_value_for_option(name, options)
@@ -239,11 +239,11 @@ module Rails
         end
       end
 
-      protected
+      private
 
         # Check whether the given class names are already taken by user
         # application or Ruby on Rails.
-        def class_collisions(*class_names) #:nodoc:
+        def class_collisions(*class_names)
           return unless behavior == :invoke
 
           class_names.flatten.each do |class_name|
@@ -264,7 +264,7 @@ module Rails
         end
 
         # Takes in an array of nested modules and extracts the last module
-        def extract_last_module(nesting)
+        def extract_last_module(nesting) # :doc:
           nesting.inject(Object) do |last_module, nest|
             break unless last_module.const_defined?(nest, false)
             last_module.const_get(nest)
@@ -272,12 +272,12 @@ module Rails
         end
 
         # Use Rails default banner.
-        def self.banner
-          "rails generate #{namespace.sub(/^rails:/,'')} #{arguments.map(&:usage).join(' ')} [options]".gsub(/\s+/, " ")
+        def self.banner # :doc:
+          "rails generate #{namespace.sub(/^rails:/, '')} #{arguments.map(&:usage).join(' ')} [options]".gsub(/\s+/, " ")
         end
 
         # Sets the base_name taking into account the current class namespace.
-        def self.base_name
+        def self.base_name # :doc:
           @base_name ||= begin
             if base = name.to_s.split("::").first
               base.underscore
@@ -287,7 +287,7 @@ module Rails
 
         # Removes the namespaces and get the generator name. For example,
         # Rails::Generators::ModelGenerator will return "model" as generator name.
-        def self.generator_name
+        def self.generator_name # :doc:
           @generator_name ||= begin
             if generator = name.to_s.split("::").last
               generator.sub!(/Generator$/, "")
@@ -298,18 +298,18 @@ module Rails
 
         # Returns the default value for the option name given doing a lookup in
         # Rails::Generators.options.
-        def self.default_value_for_option(name, options)
+        def self.default_value_for_option(name, options) # :doc:
           default_for_option(Rails::Generators.options, name, options, options[:default])
         end
 
         # Returns default aliases for the option name given doing a lookup in
         # Rails::Generators.aliases.
-        def self.default_aliases_for_option(name, options)
+        def self.default_aliases_for_option(name, options) # :doc:
           default_for_option(Rails::Generators.aliases, name, options, options[:aliases])
         end
 
         # Returns default for the option name given doing a lookup in config.
-        def self.default_for_option(config, name, options, default)
+        def self.default_for_option(config, name, options, default) # :doc:
           if generator_name && (c = config[generator_name.to_sym]) && c.key?(name)
             c[name]
           elsif base_name && (c = config[base_name.to_sym]) && c.key?(name)
@@ -343,7 +343,7 @@ module Rails
 
         # Small macro to add ruby as an option to the generator with proper
         # default value plus an instance helper method called shebang.
-        def self.add_shebang_option!
+        def self.add_shebang_option! # :doc:
           class_option :ruby, type: :string, aliases: "-r", default: Thor::Util.ruby_command,
                               desc: "Path to the Ruby binary of your choice", banner: "PATH"
 
@@ -361,7 +361,7 @@ module Rails
           }
         end
 
-        def self.usage_path
+        def self.usage_path # :doc:
           paths = [
             source_root && File.expand_path("../USAGE", source_root),
             default_generator_root && File.join(default_generator_root, "USAGE")
@@ -369,7 +369,7 @@ module Rails
           paths.compact.detect { |path| File.exist? path }
         end
 
-        def self.default_generator_root
+        def self.default_generator_root # :doc:
           path = File.expand_path(File.join(base_name, generator_name), base_root)
           path if File.exist?(path)
         end
diff --git a/railties/lib/rails/generators/erb.rb b/railties/lib/rails/generators/erb.rb
index d01502002f..d5e326d6ee 100644
--- a/railties/lib/rails/generators/erb.rb
+++ b/railties/lib/rails/generators/erb.rb
@@ -3,7 +3,7 @@ require "rails/generators/named_base"
 module Erb # :nodoc:
   module Generators # :nodoc:
     class Base < Rails::Generators::NamedBase #:nodoc:
-      protected
+      private
 
         def formats
           [format]
diff --git a/railties/lib/rails/generators/erb/mailer/mailer_generator.rb b/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
index f150240908..677f8041ae 100644
--- a/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
+++ b/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
@@ -26,7 +26,7 @@ module Erb # :nodoc:
         end
       end
 
-      protected
+      private
 
         def formats
           [:text, :html]
diff --git a/railties/lib/rails/generators/erb/scaffold/scaffold_generator.rb b/railties/lib/rails/generators/erb/scaffold/scaffold_generator.rb
index 154d85f381..0d77ef21da 100644
--- a/railties/lib/rails/generators/erb/scaffold/scaffold_generator.rb
+++ b/railties/lib/rails/generators/erb/scaffold/scaffold_generator.rb
@@ -21,7 +21,7 @@ module Erb # :nodoc:
         end
       end
 
-    protected
+    private
 
       def available_views
         %w(index edit show new _form)
diff --git a/railties/lib/rails/generators/generated_attribute.rb b/railties/lib/rails/generators/generated_attribute.rb
index 61181b7b97..baed7bf1e3 100644
--- a/railties/lib/rails/generators/generated_attribute.rb
+++ b/railties/lib/rails/generators/generated_attribute.rb
@@ -56,7 +56,7 @@ module Rails
         end
       end
 
-      def initialize(name, type=nil, index_type=false, attr_options={})
+      def initialize(name, type = nil, index_type = false, attr_options = {})
         @name           = name
         @type           = type || :string
         @has_index      = INDEX_OPTIONS.include?(index_type)
@@ -151,7 +151,7 @@ module Rails
       end
 
       def inject_options
-        "".tap { |s| options_for_migration.each { |k,v| s << ", #{k}: #{v.inspect}" } }
+        "".tap { |s| options_for_migration.each { |k, v| s << ", #{k}: #{v.inspect}" } }
       end
 
       def inject_index_options
diff --git a/railties/lib/rails/generators/migration.rb b/railties/lib/rails/generators/migration.rb
index 7290e235a1..0d63b9a5c9 100644
--- a/railties/lib/rails/generators/migration.rb
+++ b/railties/lib/rails/generators/migration.rb
@@ -52,7 +52,7 @@ module Rails
       #
       #   migration_template "migration.rb", "db/migrate/add_foo_to_bar.rb"
       def migration_template(source, destination, config = {})
-        source  = File.expand_path(find_in_source_paths(source.to_s))
+        source = File.expand_path(find_in_source_paths(source.to_s))
 
         set_migration_assigns!(destination)
         context = instance_eval("binding")
diff --git a/railties/lib/rails/generators/named_base.rb b/railties/lib/rails/generators/named_base.rb
index c39ea24935..e3660b012a 100644
--- a/railties/lib/rails/generators/named_base.rb
+++ b/railties/lib/rails/generators/named_base.rb
@@ -32,145 +32,145 @@ module Rails
         end
       end
 
+      # TODO Change this to private once we've dropped Ruby 2.2 support.
+      # Workaround for Ruby 2.2 "private attribute?" warning.
       protected
         attr_reader :file_name
 
+      private
+
         # FIXME: We are avoiding to use alias because a bug on thor that make
         # this method public and add it to the task list.
-        def singular_name
+        def singular_name # :doc:
           file_name
         end
 
         # Wrap block with namespace of current application
         # if namespace exists and is not skipped
-        def module_namespacing(&block)
+        def module_namespacing(&block) # :doc:
           content = capture(&block)
           content = wrap_with_namespace(content) if namespaced?
           concat(content)
         end
 
-        def indent(content, multiplier = 2)
+        def indent(content, multiplier = 2) # :doc:
           spaces = " " * multiplier
           content.each_line.map { |line| line.blank? ? line : "#{spaces}#{line}" }.join
         end
 
-        def wrap_with_namespace(content)
+        def wrap_with_namespace(content) # :doc:
           content = indent(content).chomp
           "module #{namespace.name}\n#{content}\nend\n"
         end
 
-        def inside_template
+        def inside_template # :doc:
           @inside_template = true
           yield
         ensure
           @inside_template = false
         end
 
-        def inside_template?
+        def inside_template? # :doc:
           @inside_template
         end
 
-        def namespace
+        def namespace # :doc:
           Rails::Generators.namespace
         end
 
-        def namespaced?
+        def namespaced? # :doc:
           !options[:skip_namespace] && namespace
         end
 
-        def file_path
+        def file_path # :doc:
           @file_path ||= (class_path + [file_name]).join("/")
         end
 
-        def class_path
+        def class_path # :doc:
           inside_template? || !namespaced? ? regular_class_path : namespaced_class_path
         end
 
-        def regular_class_path
+        def regular_class_path # :doc:
           @class_path
         end
 
-        def namespaced_file_path
-          @namespaced_file_path ||= namespaced_class_path.join("/")
-        end
-
-        def namespaced_class_path
+        def namespaced_class_path # :doc:
           @namespaced_class_path ||= [namespaced_path] + @class_path
         end
 
-        def namespaced_path
+        def namespaced_path # :doc:
           @namespaced_path ||= namespace.name.split("::").first.underscore
         end
 
-        def class_name
+        def class_name # :doc:
           (class_path + [file_name]).map!(&:camelize).join("::")
         end
 
-        def human_name
+        def human_name # :doc:
           @human_name ||= singular_name.humanize
         end
 
-        def plural_name
+        def plural_name # :doc:
           @plural_name ||= singular_name.pluralize
         end
 
-        def i18n_scope
+        def i18n_scope # :doc:
           @i18n_scope ||= file_path.tr("/", ".")
         end
 
-        def table_name
+        def table_name # :doc:
           @table_name ||= begin
             base = pluralize_table_names? ? plural_name : singular_name
             (class_path + [base]).join("_")
           end
         end
 
-        def uncountable?
+        def uncountable? # :doc:
           singular_name == plural_name
         end
 
-        def index_helper
+        def index_helper # :doc:
           uncountable? ? "#{plural_table_name}_index" : plural_table_name
         end
 
-        def show_helper
+        def show_helper # :doc:
           "#{singular_table_name}_url(@#{singular_table_name})"
         end
 
-        def edit_helper
+        def edit_helper # :doc:
           "edit_#{show_helper}"
         end
 
-        def new_helper
+        def new_helper # :doc:
           "new_#{singular_table_name}_url"
         end
 
-        def singular_table_name
+        def singular_table_name # :doc:
           @singular_table_name ||= (pluralize_table_names? ? table_name.singularize : table_name)
         end
 
-        def plural_table_name
+        def plural_table_name # :doc:
           @plural_table_name ||= (pluralize_table_names? ? table_name : table_name.pluralize)
         end
 
-        def plural_file_name
+        def plural_file_name # :doc:
           @plural_file_name ||= file_name.pluralize
         end
 
-        def fixture_file_name
+        def fixture_file_name # :doc:
           @fixture_file_name ||= (pluralize_table_names? ? plural_file_name : file_name)
         end
 
-        def route_url
+        def route_url # :doc:
           @route_url ||= class_path.collect { |dname| "/" + dname }.join + "/" + plural_file_name
         end
 
-        def url_helper_prefix
+        def url_helper_prefix # :doc:
           @url_helper_prefix ||= (class_path + [file_name]).join("_")
         end
 
         # Tries to retrieve the application name or simply return application.
-        def application_name
+        def application_name # :doc:
           if defined?(Rails) && Rails.application
             Rails.application.class.name.split("::").first.underscore
           else
@@ -178,20 +178,20 @@ module Rails
           end
         end
 
-        def assign_names!(name) #:nodoc:
+        def assign_names!(name)
           @class_path = name.include?("/") ? name.split("/") : name.split("::")
           @class_path.map!(&:underscore)
           @file_name = @class_path.pop
         end
 
         # Convert attributes array into GeneratedAttribute objects.
-        def parse_attributes! #:nodoc:
+        def parse_attributes!
           self.attributes = (attributes || []).map do |attr|
             Rails::Generators::GeneratedAttribute.parse(attr)
           end
         end
 
-        def attributes_names
+        def attributes_names # :doc:
           @attributes_names ||= attributes.each_with_object([]) do |a, names|
             names << a.column_name
             names << "password_confirmation" if a.password_digest?
@@ -199,11 +199,11 @@ module Rails
           end
         end
 
-        def pluralize_table_names?
+        def pluralize_table_names? # :doc:
           !defined?(ActiveRecord::Base) || ActiveRecord::Base.pluralize_table_names
         end
 
-        def mountable_engine?
+        def mountable_engine? # :doc:
           defined?(ENGINE_ROOT) && namespaced?
         end
 
@@ -217,7 +217,7 @@ module Rails
         # If the generator is invoked with class name Admin, it will check for
         # the presence of "AdminDecorator".
         #
-        def self.check_class_collision(options={})
+        def self.check_class_collision(options = {}) # :doc:
           define_method :check_class_collision do
             name = if self.respond_to?(:controller_class_name) # for ScaffoldBase
               controller_class_name
diff --git a/railties/lib/rails/generators/rails/app/app_generator.rb b/railties/lib/rails/generators/rails/app/app_generator.rb
index 9f9c50ca10..070a6ac124 100644
--- a/railties/lib/rails/generators/rails/app/app_generator.rb
+++ b/railties/lib/rails/generators/rails/app/app_generator.rb
@@ -56,7 +56,7 @@ module Rails
     def app
       directory "app"
 
-      keep_file  "app/assets/images"
+      keep_file "app/assets/images"
       empty_directory_with_keep_file "app/assets/javascripts/channels" unless options[:skip_action_cable]
 
       keep_file  "app/controllers/concerns"
@@ -151,19 +151,12 @@ module Rails
     end
 
     def vendor
-      vendor_javascripts
-      vendor_stylesheets
-    end
+      empty_directory_with_keep_file "vendor"
 
-    def vendor_javascripts
-      unless options[:skip_javascript]
-        empty_directory_with_keep_file "vendor/assets/javascripts"
+      unless options[:skip_yarn]
+        template "package.json", "vendor/package.json"
       end
     end
-
-    def vendor_stylesheets
-      empty_directory_with_keep_file "vendor/assets/stylesheets"
-    end
   end
 
   module Generators
@@ -193,9 +186,11 @@ module Rails
           raise Error, "Invalid value for --database option. Supported for preconfiguration are: #{DATABASES.join(", ")}."
         end
 
-        # Force sprockets to be skipped when generating API only apps.
+        # Force sprockets and yarn to be skipped when generating API only apps.
         # Can't modify options hash as it's frozen by default.
-        self.options = options.merge(skip_sprockets: true, skip_javascript: true).freeze if options[:api]
+        if options[:api]
+          self.options = options.merge(skip_sprockets: true, skip_javascript: true, skip_yarn: true).freeze
+        end
       end
 
       public_task :set_default_accessors!
@@ -205,8 +200,8 @@ module Rails
         build(:readme)
         build(:rakefile)
         build(:configru)
-        build(:gitignore) unless options[:skip_git]
-        build(:gemfile)   unless options[:skip_gemfile]
+        build(:gitignore)   unless options[:skip_git]
+        build(:gemfile)     unless options[:skip_gemfile]
       end
 
       def create_app_files
@@ -241,6 +236,7 @@ module Rails
       end
 
       def create_db_files
+        return if options[:skip_active_record]
         build(:db)
       end
 
@@ -266,6 +262,10 @@ module Rails
 
       def create_vendor_files
         build(:vendor)
+
+        if options[:skip_yarn]
+          remove_file "vendor/package.json"
+        end
       end
 
       def delete_app_assets_if_api_option
@@ -273,7 +273,6 @@ module Rails
           remove_dir "app/assets"
           remove_dir "lib/assets"
           remove_dir "tmp/cache/assets"
-          remove_dir "vendor/assets"
         end
       end
 
@@ -349,23 +348,27 @@ module Rails
         end
       end
 
+      def delete_bin_yarn_if_api_option
+        remove_file "bin/yarn" if options[:api]
+      end
+
       def finish_template
         build(:leftovers)
       end
 
       public_task :apply_rails_template, :run_bundle
-      public_task :generate_spring_binstubs
+      public_task :run_webpack, :generate_spring_binstubs
 
       def run_after_bundle_callbacks
         @after_bundle_callbacks.each(&:call)
       end
 
-    protected
-
       def self.banner
         "rails new #{arguments.map(&:usage).join(' ')} [options]"
       end
 
+    private
+
       # Define file as an alias to create_file for backwards compatibility.
       def file(*args, &block)
         create_file(*args, &block)
@@ -422,7 +425,7 @@ module Rails
           "/opt/local/var/run/mysql4/mysqld.sock",  # mac + darwinports + mysql4
           "/opt/local/var/run/mysql5/mysqld.sock",  # mac + darwinports + mysql5
           "/opt/lampp/var/mysql/mysql.sock"         # xampp for linux
-        ].find { |f| File.exist?(f) } unless RbConfig::CONFIG["host_os"] =~ /mswin|mingw/
+        ].find { |f| File.exist?(f) } unless Gem.win_platform?
       end
 
       def get_builder_class
diff --git a/railties/lib/rails/generators/rails/app/templates/Gemfile b/railties/lib/rails/generators/rails/app/templates/Gemfile
index 422217286c..f1015b16d5 100644
--- a/railties/lib/rails/generators/rails/app/templates/Gemfile
+++ b/railties/lib/rails/generators/rails/app/templates/Gemfile
@@ -1,5 +1,10 @@
 source 'https://rubygems.org'
 
+git_source(:github) do |repo_name|
+  repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
+  "https://github.com/#{repo_name}.git"
+end
+
 <% gemfile_entries.each do |gem| -%>
 <% if gem.comment -%>
 
diff --git a/railties/lib/rails/generators/rails/app/templates/app/assets/javascripts/application.js.tt b/railties/lib/rails/generators/rails/app/templates/app/assets/javascripts/application.js.tt
index c88426ec06..25870f19c8 100644
--- a/railties/lib/rails/generators/rails/app/templates/app/assets/javascripts/application.js.tt
+++ b/railties/lib/rails/generators/rails/app/templates/app/assets/javascripts/application.js.tt
@@ -1,8 +1,8 @@
 // This is a manifest file that'll be compiled into application.js, which will include all the files
 // listed below.
 //
-// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
-// or any plugin's vendor/assets/javascripts directory can be referenced here using a relative path.
+// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, or any plugin's 
+// vendor/assets/javascripts directory can be referenced here using a relative path.
 //
 // It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
 // compiled file. JavaScript code in this file should be added after the last require_* statement.
@@ -11,9 +11,11 @@
 // about supported directives.
 //
 <% unless options[:skip_javascript] -%>
+<% if options[:javascript] -%>
 //= require <%= options[:javascript] %>
-//= require <%= options[:javascript] %>_ujs
-<% if gemfile_entries.any? { |m| m.name == "turbolinks" } -%>
+<% end -%>
+//= require rails-ujs
+<% unless options[:skip_turbolinks] -%>
 //= require turbolinks
 <% end -%>
 <% end -%>
diff --git a/railties/lib/rails/generators/rails/app/templates/app/assets/stylesheets/application.css b/railties/lib/rails/generators/rails/app/templates/app/assets/stylesheets/application.css
index 0ebd7fe829..865300bef9 100644
--- a/railties/lib/rails/generators/rails/app/templates/app/assets/stylesheets/application.css
+++ b/railties/lib/rails/generators/rails/app/templates/app/assets/stylesheets/application.css
@@ -2,8 +2,8 @@
  * This is a manifest file that'll be compiled into application.css, which will include all the files
  * listed below.
  *
- * Any CSS and SCSS file within this directory, lib/assets/stylesheets, vendor/assets/stylesheets,
- * or any plugin's vendor/assets/stylesheets directory can be referenced here using a relative path.
+ * Any CSS and SCSS file within this directory, lib/assets/stylesheets, or any plugin's 
+ * vendor/assets/stylesheets directory can be referenced here using a relative path.
  *
  * You're free to add application-wide styles to this file and they'll appear at the bottom of the
  * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
diff --git a/railties/lib/rails/generators/rails/app/templates/app/views/layouts/application.html.erb.tt b/railties/lib/rails/generators/rails/app/templates/app/views/layouts/application.html.erb.tt
index d51f79bd49..5460155b3e 100644
--- a/railties/lib/rails/generators/rails/app/templates/app/views/layouts/application.html.erb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/app/views/layouts/application.html.erb.tt
@@ -7,7 +7,7 @@
     <%- if options[:skip_javascript] -%>
     <%%= stylesheet_link_tag    'application', media: 'all' %>
     <%- else -%>
-      <%- if gemfile_entries.any? { |m| m.name == 'turbolinks' } -%>
+      <%- unless options[:skip_turbolinks] -%>
     <%%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
     <%%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %>
       <%- else -%>
diff --git a/railties/lib/rails/generators/rails/app/templates/bin/setup b/railties/lib/rails/generators/rails/app/templates/bin/setup.tt
index acae810c1a..c6607dbb2b 100644
--- a/railties/lib/rails/generators/rails/app/templates/bin/setup
+++ b/railties/lib/rails/generators/rails/app/templates/bin/setup.tt
@@ -16,7 +16,12 @@ chdir APP_ROOT do
   puts '== Installing dependencies =='
   system! 'gem install bundler --conservative'
   system('bundle check') || system!('bundle install')
+<% unless options[:skip_yarn] %>
+  # Install JavaScript dependencies if using Yarn
+  # system('bin/yarn')
 
+<% end %>
+<% unless options.skip_active_record -%>
   # puts "\n== Copying sample files =="
   # unless File.exist?('config/database.yml')
   #   cp 'config/database.yml.sample', 'config/database.yml'
@@ -24,6 +29,7 @@ chdir APP_ROOT do
 
   puts "\n== Preparing database =="
   system! 'bin/rails db:setup'
+<% end -%>
 
   puts "\n== Removing old logs and tempfiles =="
   system! 'bin/rails log:clear tmp:clear'
diff --git a/railties/lib/rails/generators/rails/app/templates/bin/update b/railties/lib/rails/generators/rails/app/templates/bin/update.tt
index 770a605fed..d23af018c7 100644
--- a/railties/lib/rails/generators/rails/app/templates/bin/update
+++ b/railties/lib/rails/generators/rails/app/templates/bin/update.tt
@@ -16,9 +16,10 @@ chdir APP_ROOT do
   puts '== Installing dependencies =='
   system! 'gem install bundler --conservative'
   system('bundle check') || system!('bundle install')
-
+<% unless options.skip_active_record -%>
   puts "\n== Updating database =="
   system! 'bin/rails db:migrate'
+<% end -%>
 
   puts "\n== Removing old logs and tempfiles =="
   system! 'bin/rails log:clear tmp:clear'
diff --git a/railties/lib/rails/generators/rails/app/templates/bin/yarn b/railties/lib/rails/generators/rails/app/templates/bin/yarn
new file mode 100644
index 0000000000..872438cecb
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/bin/yarn
@@ -0,0 +1,9 @@
+VENDOR_PATH = File.expand_path('../vendor', __dir__)
+Dir.chdir(VENDOR_PATH) do
+  begin
+    exec "yarnpkg #{ARGV.join(" ")}"
+  rescue Errno::ENOENT
+    puts "Yarn executable was not detected in the system."
+    puts "Download Yarn at https://yarnpkg.com/en/docs/install"
+  end
+end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/assets.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/initializers/assets.rb.tt
index 2318cf59ff..f5d03fb117 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/assets.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/assets.rb.tt
@@ -3,8 +3,12 @@
 # Version of your assets, change this if you want to expire all your assets.
 Rails.application.config.assets.version = '1.0'
 
-# Add additional assets to the asset load path
+# Add additional assets to the asset load path.
 # Rails.application.config.assets.paths << Emoji.images_path
+<%- unless options[:skip_yarn] -%>
+# Add Yarn node_modules folder to the asset load path.
+Rails.application.config.assets.paths << Rails.root.join('vendor/node_modules')
+<%- end -%>
 
 # Precompile additional assets.
 # application.js, application.css, and all non-JS/CSS in the app/assets
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults.rb.tt
index 5ad18cc5ad..3ad3eba98a 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults.rb.tt
@@ -32,7 +32,9 @@ ActiveSupport.halt_callback_chains_on_return_false = <%= options[:update] ? true
 # Configure SSL options to enable HSTS with subdomains. Previous versions had false.
 Rails.application.config.ssl_options = { hsts: { subdomains: true } }
 <%- end -%>
+<%- unless options[:skip_sprockets] -%>
 
 # Unknown asset fallback will return the path passed in when the given
 # asset is not present in the asset pipeline.
 Rails.application.config.assets.unknown_asset_fallback = <%= options[:update] ? true : false %>
+<%- end -%>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/puma.rb b/railties/lib/rails/generators/rails/app/templates/config/puma.rb
index 7ee948002e..1e19380dcb 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/puma.rb
+++ b/railties/lib/rails/generators/rails/app/templates/config/puma.rb
@@ -1,13 +1,13 @@
 # Puma can serve each request in a thread from an internal thread pool.
-# The `threads` method setting takes two numbers a minimum and maximum.
+# The `threads` method setting takes two numbers: a minimum and maximum.
 # Any libraries that use thread pools should be configured to match
 # the maximum value specified for Puma. Default is set to 5 threads for minimum
-# and maximum, this matches the default thread size of Active Record.
+# and maximum; this matches the default thread size of Active Record.
 #
 threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
 threads threads_count, threads_count
 
-# Specifies the `port` that Puma will listen on to receive requests, default is 3000.
+# Specifies the `port` that Puma will listen on to receive requests; default is 3000.
 #
 port        ENV.fetch("PORT") { 3000 }
 
@@ -42,9 +42,9 @@ environment ENV.fetch("RAILS_ENV") { "development" }
 
 # The code in the `on_worker_boot` will be called if you are using
 # clustered mode by specifying a number of `workers`. After each worker
-# process is booted this block will be run, if you are using `preload_app!`
-# option you will want to use this block to reconnect to any threads
-# or connections that may have been created at application boot, Ruby
+# process is booted, this block will be run. If you are using the `preload_app!`
+# option, you will want to use this block to reconnect to any threads
+# or connections that may have been created at application boot, as Ruby
 # cannot share connections between processes.
 #
 # on_worker_boot do
diff --git a/railties/lib/rails/generators/rails/app/templates/gitignore b/railties/lib/rails/generators/rails/app/templates/gitignore
index 0e66cc4237..709b341387 100644
--- a/railties/lib/rails/generators/rails/app/templates/gitignore
+++ b/railties/lib/rails/generators/rails/app/templates/gitignore
@@ -21,5 +21,8 @@
 !/tmp/.keep
 <% end -%>
 
-# Ignore Byebug command history file.
+<% unless options[:skip_yarn] -%>
+/vendor/node_modules
+
+<% end -%>
 .byebug_history
diff --git a/railties/lib/rails/generators/rails/app/templates/package.json b/railties/lib/rails/generators/rails/app/templates/package.json
new file mode 100644
index 0000000000..46db57dcbe
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/package.json
@@ -0,0 +1,5 @@
+{
+  "name": "<%= app_name %>",
+  "private": true,
+  "dependencies": {}
+}
diff --git a/railties/lib/rails/generators/rails/assets/assets_generator.rb b/railties/lib/rails/generators/rails/assets/assets_generator.rb
index 265dada2ca..95d00c2d39 100644
--- a/railties/lib/rails/generators/rails/assets/assets_generator.rb
+++ b/railties/lib/rails/generators/rails/assets/assets_generator.rb
@@ -7,7 +7,7 @@ module Rails
       class_option :javascript_engine, desc: "Engine for JavaScripts"
       class_option :stylesheet_engine, desc: "Engine for Stylesheets"
 
-      protected
+      private
 
         def asset_name
           file_name
diff --git a/railties/lib/rails/generators/rails/controller/controller_generator.rb b/railties/lib/rails/generators/rails/controller/controller_generator.rb
index 213de37cce..06bdb8b5ce 100644
--- a/railties/lib/rails/generators/rails/controller/controller_generator.rb
+++ b/railties/lib/rails/generators/rails/controller/controller_generator.rb
@@ -3,6 +3,8 @@ module Rails
     class ControllerGenerator < NamedBase # :nodoc:
       argument :actions, type: :array, default: [], banner: "action action"
       class_option :skip_routes, type: :boolean, desc: "Don't add routes to config/routes.rb."
+      class_option :helper, type: :boolean
+      class_option :assets, type: :boolean
 
       check_class_collision suffix: "Controller"
 
@@ -14,7 +16,7 @@ module Rails
         unless options[:skip_routes]
           actions.reverse_each do |action|
             # route prepends two spaces onto the front of the string that is passed, this corrects that.
-            route generate_routing_code(action)[2..-1]
+            route indent(generate_routing_code(action), 2)[2..-1]
           end
         end
       end
@@ -32,27 +34,30 @@ module Rails
         #   end
         # end
         def generate_routing_code(action)
-          depth = regular_class_path.length
+          depth = 0
+          lines = []
+
           # Create 'namespace' ladder
           # namespace :foo do
           #   namespace :bar do
-          namespace_ladder = regular_class_path.each_with_index.map do |ns, i|
-            indent("  namespace :#{ns} do\n", i * 2)
-          end.join
+          regular_class_path.each do |ns|
+            lines << indent("namespace :#{ns} do\n", depth * 2)
+            depth += 1
+          end
 
           # Create route
           #     get 'baz/index'
-          route = indent(%{  get '#{file_name}/#{action}'\n}, depth * 2)
+          lines << indent(%{get '#{file_name}/#{action}'\n}, depth * 2)
 
           # Create `end` ladder
           #   end
           # end
-          end_ladder = (1..depth).reverse_each.map do |i|
-            indent("end\n", i * 2)
-          end.join
+          until depth.zero?
+            depth -= 1
+            lines << indent("end\n", depth * 2)
+          end
 
-          # Combine the 3 parts to generate complete route entry
-          namespace_ladder + route + end_ladder
+          lines.join
         end
     end
   end
diff --git a/railties/lib/rails/generators/rails/generator/generator_generator.rb b/railties/lib/rails/generators/rails/generator/generator_generator.rb
index 8040ec5e7b..299a7da5f1 100644
--- a/railties/lib/rails/generators/rails/generator/generator_generator.rb
+++ b/railties/lib/rails/generators/rails/generator/generator_generator.rb
@@ -12,7 +12,7 @@ module Rails
 
       hook_for :test_framework
 
-      protected
+      private
 
         def generator_dir
           if options[:namespace]
diff --git a/railties/lib/rails/generators/rails/plugin/plugin_generator.rb b/railties/lib/rails/generators/rails/plugin/plugin_generator.rb
index 9ffeab4fbe..4cf4f8cd9a 100644
--- a/railties/lib/rails/generators/rails/plugin/plugin_generator.rb
+++ b/railties/lib/rails/generators/rails/plugin/plugin_generator.rb
@@ -81,7 +81,7 @@ task default: :test
     end
 
     PASSTHROUGH_OPTIONS = [
-      :skip_active_record, :skip_action_mailer, :skip_javascript, :database,
+      :skip_active_record, :skip_action_mailer, :skip_javascript, :skip_sprockets, :database,
       :javascript, :quiet, :pretend, :force, :skip
     ]
 
@@ -270,8 +270,8 @@ task default: :test
         @name ||= begin
           # same as ActiveSupport::Inflector#underscore except not replacing '-'
           underscored = original_name.dup
-          underscored.gsub!(/([A-Z]+)([A-Z][a-z])/,'\1_\2')
-          underscored.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
+          underscored.gsub!(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
+          underscored.gsub!(/([a-z\d])([A-Z])/, '\1_\2')
           underscored.downcase!
 
           underscored
@@ -283,10 +283,10 @@ task default: :test
       end
 
       def namespaced_name
-        @namespaced_name ||= name.gsub("-", "/")
+        @namespaced_name ||= name.tr("-", "/")
       end
 
-    protected
+    private
 
       def create_dummy_app(path = nil)
         dummy_path(path) if path
diff --git a/railties/lib/rails/generators/resource_helpers.rb b/railties/lib/rails/generators/resource_helpers.rb
index 6d80003271..978b053308 100644
--- a/railties/lib/rails/generators/resource_helpers.rb
+++ b/railties/lib/rails/generators/resource_helpers.rb
@@ -23,10 +23,14 @@ module Rails
         assign_controller_names!(controller_name.pluralize)
       end
 
+      # TODO Change this to private once we've dropped Ruby 2.2 support.
+      # Workaround for Ruby 2.2 "private attribute?" warning.
       protected
 
         attr_reader :controller_name, :controller_file_name
 
+      private
+
         def controller_class_path
           if options[:model_name]
             @controller_class_path
@@ -73,7 +77,7 @@ module Rails
         end
 
         # Initialize ORM::Generators::ActiveModel to access instance methods.
-        def orm_instance(name=singular_table_name)
+        def orm_instance(name = singular_table_name)
           @orm_instance ||= orm_class.new(name)
         end
     end
diff --git a/railties/lib/rails/generators/test_unit/generator/generator_generator.rb b/railties/lib/rails/generators/test_unit/generator/generator_generator.rb
index 59f8d40343..6b6e094453 100644
--- a/railties/lib/rails/generators/test_unit/generator/generator_generator.rb
+++ b/railties/lib/rails/generators/test_unit/generator/generator_generator.rb
@@ -12,7 +12,7 @@ module TestUnit # :nodoc:
         template "generator_test.rb", File.join("test/lib/generators", class_path, "#{file_name}_generator_test.rb")
       end
 
-    protected
+    private
 
       def generator_path
         if options[:namespace]
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 806279788e..67bff8e4f9 100644
--- a/railties/lib/rails/generators/test_unit/mailer/mailer_generator.rb
+++ b/railties/lib/rails/generators/test_unit/mailer/mailer_generator.rb
@@ -17,7 +17,7 @@ module TestUnit # :nodoc:
         template "preview.rb", File.join("test/mailers/previews", class_path, "#{file_name}_mailer_preview.rb")
       end
 
-      protected
+      private
         def file_name
           @_file_name ||= super.gsub(/_mailer/i, "")
         end
diff --git a/railties/lib/rails/generators/testing/behaviour.rb b/railties/lib/rails/generators/testing/behaviour.rb
index a1e5a233b9..64d641d096 100644
--- a/railties/lib/rails/generators/testing/behaviour.rb
+++ b/railties/lib/rails/generators/testing/behaviour.rb
@@ -82,23 +82,23 @@ module Rails
           Rails::Generators::GeneratedAttribute.parse([name, attribute_type, index].compact.join(":"))
         end
 
-        protected
+        private
 
-          def destination_root_is_set? # :nodoc:
+          def destination_root_is_set?
             raise "You need to configure your Rails::Generators::TestCase destination root." unless destination_root
           end
 
-          def ensure_current_path # :nodoc:
+          def ensure_current_path
             cd current_path
           end
 
           # Clears all files and directories in destination.
-          def prepare_destination
+          def prepare_destination # :doc:
             rm_rf(destination_root)
             mkdir_p(destination_root)
           end
 
-          def migration_file_name(relative) # :nodoc:
+          def migration_file_name(relative)
             absolute = File.expand_path(relative, destination_root)
             dirname, file_name = File.dirname(absolute), File.basename(absolute).sub(/\.rb$/, "")
             Dir.glob("#{dirname}/[0-9]*_*.rb").grep(/\d+_#{file_name}.rb$/).first
diff --git a/railties/lib/rails/initializable.rb b/railties/lib/rails/initializable.rb
index 81b1cd8110..a2615d5efd 100644
--- a/railties/lib/rails/initializable.rb
+++ b/railties/lib/rails/initializable.rb
@@ -53,7 +53,7 @@ module Rails
       end
     end
 
-    def run_initializers(group=:default, *args)
+    def run_initializers(group = :default, *args)
       return if instance_variable_defined?(:@ran)
       initializers.tsort_each do |initializer|
         initializer.run(*args) if initializer.belongs_to?(group)
diff --git a/railties/lib/rails/mailers_controller.rb b/railties/lib/rails/mailers_controller.rb
index 95de998208..000ce40fbc 100644
--- a/railties/lib/rails/mailers_controller.rb
+++ b/railties/lib/rails/mailers_controller.rb
@@ -40,12 +40,12 @@ class Rails::MailersController < Rails::ApplicationController # :nodoc:
     end
   end
 
-  protected
-    def show_previews?
+  private
+    def show_previews? # :doc:
       ActionMailer::Base.show_previews
     end
 
-    def find_preview
+    def find_preview # :doc:
       candidates = []
       params[:path].to_s.scan(%r{/|$}) { candidates << $` }
       preview = candidates.detect { |candidate| ActionMailer::Preview.exists?(candidate) }
@@ -57,7 +57,7 @@ class Rails::MailersController < Rails::ApplicationController # :nodoc:
       end
     end
 
-    def find_preferred_part(*formats)
+    def find_preferred_part(*formats) # :doc:
       formats.each do |format|
         if part = @email.find_first_mime_type(format)
           return part
@@ -69,7 +69,7 @@ class Rails::MailersController < Rails::ApplicationController # :nodoc:
       end
     end
 
-    def find_part(format)
+    def find_part(format) # :doc:
       if part = @email.find_first_mime_type(format)
         part
       elsif @email.mime_type == format
diff --git a/railties/lib/rails/paths.rb b/railties/lib/rails/paths.rb
index 1c1810dde6..10925de8b2 100644
--- a/railties/lib/rails/paths.rb
+++ b/railties/lib/rails/paths.rb
@@ -45,7 +45,6 @@ module Rails
       attr_accessor :path
 
       def initialize(path)
-        @current = nil
         @path = path
         @root = {}
       end
diff --git a/railties/lib/rails/rack/logger.rb b/railties/lib/rails/rack/logger.rb
index e3fee75603..853fc26051 100644
--- a/railties/lib/rails/rack/logger.rb
+++ b/railties/lib/rails/rack/logger.rb
@@ -27,45 +27,43 @@ module Rails
         end
       end
 
-    protected
+      private
 
-      def call_app(request, env)
-        instrumenter = ActiveSupport::Notifications.instrumenter
-        instrumenter.start "request.action_dispatch", request: request
-        logger.info { started_request_message(request) }
-        resp = @app.call(env)
-        resp[2] = ::Rack::BodyProxy.new(resp[2]) { finish(request) }
-        resp
-      rescue Exception
-        finish(request)
-        raise
-      ensure
-        ActiveSupport::LogSubscriber.flush_all!
-      end
+        def call_app(request, env) # :doc:
+          instrumenter = ActiveSupport::Notifications.instrumenter
+          instrumenter.start "request.action_dispatch", request: request
+          logger.info { started_request_message(request) }
+          resp = @app.call(env)
+          resp[2] = ::Rack::BodyProxy.new(resp[2]) { finish(request) }
+          resp
+        rescue Exception
+          finish(request)
+          raise
+        ensure
+          ActiveSupport::LogSubscriber.flush_all!
+        end
 
-      # Started GET "/session/new" for 127.0.0.1 at 2012-09-26 14:51:42 -0700
-      def started_request_message(request)
-        'Started %s "%s" for %s at %s' % [
-          request.request_method,
-          request.filtered_path,
-          request.ip,
-          Time.now.to_default_s ]
-      end
+        # Started GET "/session/new" for 127.0.0.1 at 2012-09-26 14:51:42 -0700
+        def started_request_message(request) # :doc:
+          'Started %s "%s" for %s at %s' % [
+            request.request_method,
+            request.filtered_path,
+            request.ip,
+            Time.now.to_default_s ]
+        end
 
-      def compute_tags(request)
-        @taggers.collect do |tag|
-          case tag
-          when Proc
-            tag.call(request)
-          when Symbol
-            request.send(tag)
-          else
-            tag
+        def compute_tags(request) # :doc:
+          @taggers.collect do |tag|
+            case tag
+            when Proc
+              tag.call(request)
+            when Symbol
+              request.send(tag)
+            else
+              tag
+            end
           end
         end
-      end
-
-      private
 
         def finish(request)
           instrumenter = ActiveSupport::Notifications.instrumenter
diff --git a/railties/lib/rails/railtie.rb b/railties/lib/rails/railtie.rb
index eb3f5d4ee9..474118c0a9 100644
--- a/railties/lib/rails/railtie.rb
+++ b/railties/lib/rails/railtie.rb
@@ -132,27 +132,19 @@ module Rails
       end
 
       def rake_tasks(&blk)
-        @rake_tasks ||= []
-        @rake_tasks << blk if blk
-        @rake_tasks
+        register_block_for(:rake_tasks, &blk)
       end
 
       def console(&blk)
-        @load_console ||= []
-        @load_console << blk if blk
-        @load_console
+        register_block_for(:load_console, &blk)
       end
 
       def runner(&blk)
-        @load_runner ||= []
-        @load_runner << blk if blk
-        @load_runner
+        register_block_for(:runner, &blk)
       end
 
       def generators(&blk)
-        @generators ||= []
-        @generators << blk if blk
-        @generators
+        register_block_for(:generators, &blk)
       end
 
       def abstract_railtie?
@@ -181,8 +173,8 @@ module Rails
         instance.configure(&block)
       end
 
-      protected
-        def generate_railtie_name(string) #:nodoc:
+      private
+        def generate_railtie_name(string)
           ActiveSupport::Inflector.underscore(string).tr("/", "_")
         end
 
@@ -195,6 +187,16 @@ module Rails
             super
           end
         end
+
+        # receives an instance variable identifier, set the variable value if is
+        # blank and append given block to value, which will be used later in
+        # `#each_registered_block(type, &block)`
+        def register_block_for(type, &blk)
+          var_name = "@#{type}"
+          blocks = instance_variable_defined?(var_name) ? instance_variable_get(var_name) : instance_variable_set(var_name, [])
+          blocks << blk if blk
+          blocks
+        end
     end
 
     delegate :railtie_name, to: :class
@@ -241,6 +243,7 @@ module Rails
 
     private
 
+      # run `&block` in every registered block in `#register_block_for`
       def each_registered_block(type, &block)
         klass = self.class
         while klass.respond_to?(type)
diff --git a/railties/lib/rails/railtie/configurable.rb b/railties/lib/rails/railtie/configurable.rb
index 39f1f87575..2a8295426e 100644
--- a/railties/lib/rails/railtie/configurable.rb
+++ b/railties/lib/rails/railtie/configurable.rb
@@ -24,7 +24,7 @@ module Rails
           class_eval(&block)
         end
 
-        protected
+        private
 
           def method_missing(*args, &block)
             instance.send(*args, &block)
diff --git a/railties/lib/rails/source_annotation_extractor.rb b/railties/lib/rails/source_annotation_extractor.rb
index f0df76d3f3..3a48c4c496 100644
--- a/railties/lib/rails/source_annotation_extractor.rb
+++ b/railties/lib/rails/source_annotation_extractor.rb
@@ -44,7 +44,7 @@ class SourceAnnotationExtractor
     #
     # If +options+ has a flag <tt>:tag</tt> the tag is shown as in the example above.
     # Otherwise the string contains just line and text.
-    def to_s(options={})
+    def to_s(options = {})
       s = "[#{line.to_s.rjust(options[:indent])}] "
       s << "[#{tag}] " if options[:tag]
       s << text
@@ -66,7 +66,7 @@ class SourceAnnotationExtractor
   # See <tt>#find_in</tt> for a list of file extensions that will be taken into account.
   #
   # This class method is the single entry point for the rake tasks.
-  def self.enumerate(tag, options={})
+  def self.enumerate(tag, options = {})
     extractor = new(tag)
     dirs = options.delete(:dirs) || Annotation.directories
     extractor.display(extractor.find(dirs), options)
@@ -116,7 +116,7 @@ class SourceAnnotationExtractor
   # Otherwise it returns an empty hash.
   def extract_annotations_from(file, pattern)
     lineno = 0
-    result = File.readlines(file).inject([]) do |list, line|
+    result = File.readlines(file, encoding: Encoding::BINARY).inject([]) do |list, line|
       lineno += 1
       next list unless line =~ pattern
       list << Annotation.new(lineno, $1, $2)
@@ -126,7 +126,7 @@ class SourceAnnotationExtractor
 
   # Prints the mapping from filenames to annotations in +results+ ordered by filename.
   # The +options+ hash is passed to each annotation's +to_s+.
-  def display(results, options={})
+  def display(results, options = {})
     options[:indent] = results.flat_map { |f, a| a.map(&:line) }.max.to_s.size
     results.keys.sort.each do |file|
       puts "#{file}:"
diff --git a/railties/lib/rails/tasks/statistics.rake b/railties/lib/rails/tasks/statistics.rake
index a6cdd1e99c..8265aef10b 100644
--- a/railties/lib/rails/tasks/statistics.rake
+++ b/railties/lib/rails/tasks/statistics.rake
@@ -8,7 +8,7 @@ STATS_DIRECTORIES = [
   %w(Models             app/models),
   %w(Mailers            app/mailers),
   %w(Channels           app/channels),
-  %w(Javascripts        app/assets/javascripts),
+  %w(JavaScripts        app/assets/javascripts),
   %w(Libraries          lib/),
   %w(Tasks              lib/tasks),
   %w(APIs               app/apis),
diff --git a/railties/lib/rails/test_unit/railtie.rb b/railties/lib/rails/test_unit/railtie.rb
index d0fc795515..746120e6a1 100644
--- a/railties/lib/rails/test_unit/railtie.rb
+++ b/railties/lib/rails/test_unit/railtie.rb
@@ -14,7 +14,9 @@ module Rails
     end
 
     initializer "test_unit.line_filtering" do
-      ActiveSupport::TestCase.extend Rails::LineFiltering
+      ActiveSupport.on_load(:active_support_test_case) {
+        ActiveSupport::TestCase.extend Rails::LineFiltering
+      }
     end
 
     rake_tasks do