Merge pull request #19832 from spastorino/rails-api

Rails api

24 files changed, 541 insertions, 10 deletions

diff --git a/railties/CHANGELOG.md b/railties/CHANGELOG.md
index a0fb612cba..3536929d00 100644
--- a/railties/CHANGELOG.md
+++ b/railties/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   Add support for API only apps.
+    Middleware stack was slimmed down and it has only the needed
+    middleware for API apps & generators generates the right files,
+    folders and configurations.
+
+    *Santiago Pastorino & Jorge Bejar*
+
 *   Make generated scaffold functional tests work inside engines.
 
     *Yuji Yaginuma*
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 78a47fcda9..4fc7a1db62 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -16,7 +16,7 @@ module Rails
                     :beginning_of_week, :filter_redirect, :x
 
       attr_writer :log_level
-      attr_reader :encoding
+      attr_reader :encoding, :api_only
 
       def initialize(*)
         super
@@ -49,6 +49,7 @@ module Rails
         @eager_load                    = nil
         @secret_token                  = nil
         @secret_key_base               = nil
+        @api_only                      = false
         @x                             = Custom.new
       end
 
@@ -60,6 +61,11 @@ module Rails
         end
       end
 
+      def api_only=(value)
+        @api_only = value
+        generators.api_only = value
+      end
+
       def paths
         @paths ||= begin
           paths = super
diff --git a/railties/lib/rails/application/default_middleware_stack.rb b/railties/lib/rails/application/default_middleware_stack.rb
index 909ed5cc35..6f9ccec137 100644
--- a/railties/lib/rails/application/default_middleware_stack.rb
+++ b/railties/lib/rails/application/default_middleware_stack.rb
@@ -28,7 +28,7 @@ module Rails
 
           middleware.use ::Rack::Lock unless allow_concurrency?
           middleware.use ::Rack::Runtime
-          middleware.use ::Rack::MethodOverride
+          middleware.use ::Rack::MethodOverride unless config.api_only
           middleware.use ::ActionDispatch::RequestId
 
           # Must come after Rack::MethodOverride to properly log overridden methods
@@ -42,9 +42,9 @@ module Rails
           end
 
           middleware.use ::ActionDispatch::Callbacks
-          middleware.use ::ActionDispatch::Cookies
+          middleware.use ::ActionDispatch::Cookies unless config.api_only
 
-          if config.session_store
+          if !config.api_only && config.session_store
             if config.force_ssl && !config.session_options.key?(:secure)
               config.session_options[:secure] = true
             end
diff --git a/railties/lib/rails/configuration.rb b/railties/lib/rails/configuration.rb
index 76364cea8f..d99d27a756 100644
--- a/railties/lib/rails/configuration.rb
+++ b/railties/lib/rails/configuration.rb
@@ -74,7 +74,7 @@ module Rails
     end
 
     class Generators #:nodoc:
-      attr_accessor :aliases, :options, :templates, :fallbacks, :colorize_logging
+      attr_accessor :aliases, :options, :templates, :fallbacks, :colorize_logging, :api_only
       attr_reader :hidden_namespaces
 
       def initialize
@@ -83,6 +83,7 @@ module Rails
         @fallbacks = {}
         @templates = []
         @colorize_logging = true
+        @api_only = false
         @hidden_namespaces = []
       end
 
diff --git a/railties/lib/rails/generators.rb b/railties/lib/rails/generators.rb
index 79088bbe3c..b430cf1909 100644
--- a/railties/lib/rails/generators.rb
+++ b/railties/lib/rails/generators.rb
@@ -45,6 +45,7 @@ module Rails
 
     DEFAULT_OPTIONS = {
       rails: {
+        api: false,
         assets: true,
         force_plural: false,
         helper: true,
@@ -64,6 +65,7 @@ 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
@@ -101,6 +103,21 @@ module Rails
       @fallbacks ||= {}
     end
 
+    # Configure generators for API only applications. It basically hides
+    # everything that is usually browser related, such as assets and session
+    # migration generators, and completely disable views, helpers and assets
+    # so generators such as scaffold won't create them.
+    def self.api_only!
+      hide_namespaces "assets", "helper", "css", "js"
+
+      options[:rails].merge!(
+        api: true,
+        assets: false,
+        helper: false,
+        template_engine: nil
+      )
+    end
+
     # Remove the color from output.
     def self.no_color!
       Thor::Base.shell = Thor::Shell::Basic
diff --git a/railties/lib/rails/generators/app_base.rb b/railties/lib/rails/generators/app_base.rb
index c02b39d203..249fe96772 100644
--- a/railties/lib/rails/generators/app_base.rb
+++ b/railties/lib/rails/generators/app_base.rb
@@ -266,6 +266,8 @@ module Rails
       end
 
       def jbuilder_gemfile_entry
+        return [] if options[:api]
+
         comment = 'Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder'
         GemfileEntry.version('jbuilder', '~> 2.0', comment)
       end
diff --git a/railties/lib/rails/generators/rails/app/app_generator.rb b/railties/lib/rails/generators/rails/app/app_generator.rb
index 152c26860e..4b73313388 100644
--- a/railties/lib/rails/generators/rails/app/app_generator.rb
+++ b/railties/lib/rails/generators/rails/app/app_generator.rb
@@ -175,6 +175,9 @@ module Rails
       class_option :version, type: :boolean, aliases: "-v", group: :rails,
                              desc: "Show Rails version number and quit"
 
+      class_option :api, type: :boolean,
+                         desc: "Preconfigure smaller stack for API only apps"
+
       def initialize(*args)
         super
 
@@ -185,6 +188,10 @@ module Rails
         if !options[:skip_active_record] && !DATABASES.include?(options[:database])
           raise Error, "Invalid value for --database option. Supported for preconfiguration are: #{DATABASES.join(", ")}."
         end
+
+        # Force sprockets to be skipped when generating API only apps.
+        # Can't modify options hash as it's frozen by default.
+        self.options = options.merge(skip_sprockets: true, skip_javascript: true).freeze if options[:api]
       end
 
       public_task :set_default_accessors!
@@ -252,6 +259,28 @@ module Rails
         build(:vendor)
       end
 
+      def delete_app_assets_if_api_option
+        if options[:api]
+          remove_dir 'app/assets'
+          remove_dir 'lib/assets'
+          remove_dir 'tmp/cache/assets'
+          remove_dir 'vendor/assets'
+        end
+      end
+
+      def delete_app_helpers_if_api_option
+        if options[:api]
+          remove_dir 'app/helpers'
+          remove_dir 'test/helpers'
+        end
+      end
+
+      def delete_app_views_if_api_option
+        if options[:api]
+          remove_dir 'app/views'
+        end
+      end
+
       def delete_js_folder_skipping_javascript
         if options[:skip_javascript]
           remove_dir 'app/assets/javascripts'
@@ -270,6 +299,13 @@ module Rails
         end
       end
 
+      def delete_non_api_initializers_if_api_option
+        if options[:api]
+          remove_file 'config/initializers/session_store.rb'
+          remove_file 'config/initializers/cookies_serializer.rb'
+        end
+      end
+
       def finish_template
         build(:leftovers)
       end
diff --git a/railties/lib/rails/generators/rails/app/templates/Gemfile b/railties/lib/rails/generators/rails/app/templates/Gemfile
index 29203b9c37..606f1d4f96 100644
--- a/railties/lib/rails/generators/rails/app/templates/Gemfile
+++ b/railties/lib/rails/generators/rails/app/templates/Gemfile
@@ -21,6 +21,14 @@ source 'https://rubygems.org'
 # Use Capistrano for deployment
 # gem 'capistrano-rails', group: :development
 
+<%- if options.api? -%>
+# Use ActiveModelSerializers to serialize JSON responses
+gem 'active_model_serializers', '~> 0.10.0.rc1'
+
+# Use Rack CORS for handling Cross-Origin Resource Sharing (CORS), making cross-origin AJAX possible
+# gem 'rack-cors'
+
+<%- end -%>
 <% if RUBY_ENGINE == 'ruby' -%>
 group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
diff --git a/railties/lib/rails/generators/rails/app/templates/app/controllers/application_controller.rb.tt b/railties/lib/rails/generators/rails/app/templates/app/controllers/application_controller.rb.tt
index d83690e1b9..f726fd6305 100644
--- a/railties/lib/rails/generators/rails/app/templates/app/controllers/application_controller.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/app/controllers/application_controller.rb.tt
@@ -1,5 +1,7 @@
-class ApplicationController < ActionController::Base
+class ApplicationController < ActionController::<%= options[:api] ? "API" : "Base" %>
+<%- unless options[:api] -%>
   # Prevent CSRF attacks by raising an exception.
   # For APIs, you may want to use :null_session instead.
   protect_from_forgery with: :exception
+<%- end -%>
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/application.rb b/railties/lib/rails/generators/rails/app/templates/config/application.rb
index a2661bfb51..6b7d7abd0b 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/application.rb
+++ b/railties/lib/rails/generators/rails/app/templates/config/application.rb
@@ -32,5 +32,12 @@ module <%= app_const_base %>
     # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
     # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
     # config.i18n.default_locale = :de
+<%- if options[:api] -%>
+
+    # Only loads a smaller set of middleware suitable for API only apps.
+    # Middleware like session, flash, cookies can be added back manually.
+    # Skip views, helpers and assets when generating a new resource.
+    config.api_only = true
+<%- end -%>
   end
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/cors.rb b/railties/lib/rails/generators/rails/app/templates/config/initializers/cors.rb
new file mode 100644
index 0000000000..45c44d24f8
--- /dev/null
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/cors.rb
@@ -0,0 +1,14 @@
+# Avoid CORS issues when API is called from the frontend app
+# Handle Cross-Origin Resource Sharing (CORS) in order to accept cross-origin AJAX requests
+
+# Read more: https://github.com/cyu/rack-cors
+
+# Rails.application.config.middleware.insert_before 0, "Rack::Cors" do
+#   allow do
+#     origins 'example.com'
+#
+#     resource '*',
+#       headers: :any,
+#       methods: [:get, :post, :put, :patch, :delete, :options, :head]
+#   end
+# end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt
index 94f612c3dd..cadc85cfac 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt
@@ -5,7 +5,7 @@
 
 # Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array.
 ActiveSupport.on_load(:action_controller) do
-  wrap_parameters format: [:json] if respond_to?(:wrap_parameters)
+  wrap_parameters format: [:json]
 end
 <%- unless options.skip_active_record? -%>
 
diff --git a/railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb b/railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb
index c986f95e67..42705107ae 100644
--- a/railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb
+++ b/railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb
@@ -1,7 +1,6 @@
 module Rails
   module Generators
     class ResourceRouteGenerator < NamedBase # :nodoc:
-
       # Properly nests namespaces passed into a generator
       #
       #   $ rails generate resource admin/users/products
diff --git a/railties/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb b/railties/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb
index c01b82884d..d0b8cad896 100644
--- a/railties/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb
+++ b/railties/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb
@@ -10,11 +10,14 @@ module Rails
       class_option :helper, type: :boolean
       class_option :orm, banner: "NAME", type: :string, required: true,
                          desc: "ORM to generate the controller for"
+      class_option :api, type: :boolean,
+                         desc: "Generates API controller"
 
       argument :attributes, type: :array, default: [], banner: "field:type field:type"
 
       def create_controller_files
-        template "controller.rb", File.join('app/controllers', controller_class_path, "#{controller_file_name}_controller.rb")
+        template_file = options.api? ? "api_controller.rb" : "controller.rb"
+        template template_file, File.join('app/controllers', controller_class_path, "#{controller_file_name}_controller.rb")
       end
 
       hook_for :template_engine, :test_framework, as: :scaffold
diff --git a/railties/lib/rails/generators/rails/scaffold_controller/templates/api_controller.rb b/railties/lib/rails/generators/rails/scaffold_controller/templates/api_controller.rb
new file mode 100644
index 0000000000..bc3c9b3f6b
--- /dev/null
+++ b/railties/lib/rails/generators/rails/scaffold_controller/templates/api_controller.rb
@@ -0,0 +1,61 @@
+<% if namespaced? -%>
+require_dependency "<%= namespaced_file_path %>/application_controller"
+
+<% end -%>
+<% module_namespacing do -%>
+class <%= controller_class_name %>Controller < ApplicationController
+  before_action :set_<%= singular_table_name %>, only: [:show, :update, :destroy]
+
+  # GET <%= route_url %>
+  def index
+    @<%= plural_table_name %> = <%= orm_class.all(class_name) %>
+
+    render json: <%= "@#{plural_table_name}" %>
+  end
+
+  # GET <%= route_url %>/1
+  def show
+    render json: <%= "@#{singular_table_name}" %>
+  end
+
+  # POST <%= route_url %>
+  def create
+    @<%= singular_table_name %> = <%= orm_class.build(class_name, "#{singular_table_name}_params") %>
+
+    if @<%= orm_instance.save %>
+      render json: <%= "@#{singular_table_name}" %>, status: :created, location: <%= "@#{singular_table_name}" %>
+    else
+      render json: <%= "@#{orm_instance.errors}" %>, status: :unprocessable_entity
+    end
+  end
+
+  # PATCH/PUT <%= route_url %>/1
+  def update
+    if @<%= orm_instance.update("#{singular_table_name}_params") %>
+      render json: <%= "@#{singular_table_name}" %>
+    else
+      render json: <%= "@#{orm_instance.errors}" %>, status: :unprocessable_entity
+    end
+  end
+
+  # DELETE <%= route_url %>/1
+  def destroy
+    @<%= orm_instance.destroy %>
+  end
+
+  private
+    # Use callbacks to share common setup or constraints between actions.
+    def set_<%= singular_table_name %>
+      @<%= singular_table_name %> = <%= orm_class.find(class_name, "params[:id]") %>
+    end
+
+    # Only allow a trusted parameter "white list" through.
+    def <%= "#{singular_table_name}_params" %>
+      <%- if attributes_names.empty? -%>
+      params[:<%= singular_table_name %>]
+      <%- else -%>
+      params.require(:<%= singular_table_name %>).permit(<%= attributes_names.map { |name| ":#{name}" }.join(', ') %>)
+      <%- end -%>
+    end
+end
+<% end -%>
diff --git a/railties/lib/rails/generators/test_unit/scaffold/scaffold_generator.rb b/railties/lib/rails/generators/test_unit/scaffold/scaffold_generator.rb
index c36a64db31..d634584beb 100644
--- a/railties/lib/rails/generators/test_unit/scaffold/scaffold_generator.rb
+++ b/railties/lib/rails/generators/test_unit/scaffold/scaffold_generator.rb
@@ -8,10 +8,14 @@ module TestUnit # :nodoc:
 
       check_class_collision suffix: "ControllerTest"
 
+      class_option :api, type: :boolean,
+                         desc: "Generates API functional tests"
+
       argument :attributes, type: :array, default: [], banner: "field:type field:type"
 
       def create_test_files
-        template "functional_test.rb",
+        template_file = options.api? ? "api_functional_test.rb" : "functional_test.rb"
+        template template_file,
                  File.join("test/controllers", controller_class_path, "#{controller_file_name}_controller_test.rb")
       end
 
diff --git a/railties/lib/rails/generators/test_unit/scaffold/templates/api_functional_test.rb b/railties/lib/rails/generators/test_unit/scaffold/templates/api_functional_test.rb
new file mode 100644
index 0000000000..7e41162d47
--- /dev/null
+++ b/railties/lib/rails/generators/test_unit/scaffold/templates/api_functional_test.rb
@@ -0,0 +1,41 @@
+require 'test_helper'
+
+<% module_namespacing do -%>
+class <%= controller_class_name %>ControllerTest < ActionController::TestCase
+  setup do
+    @<%= singular_table_name %> = <%= table_name %>(:one)
+  end
+
+  test "should get index" do
+    get :index
+    assert_response :success
+    assert_not_nil assigns(:<%= table_name %>)
+  end
+
+  test "should create <%= singular_table_name %>" do
+    assert_difference('<%= class_name %>.count') do
+      post :create, params: { <%= "#{singular_table_name}: { #{attributes_hash} }" %> }
+    end
+
+    assert_response 201
+  end
+
+  test "should show <%= singular_table_name %>" do
+    get :show, params: { id: <%= "@#{singular_table_name}" %> }
+    assert_response :success
+  end
+
+  test "should update <%= singular_table_name %>" do
+    patch :update, params: { id: <%= "@#{singular_table_name}" %>, <%= "#{singular_table_name}: { #{attributes_hash} }" %> }
+    assert_response 200
+  end
+
+  test "should destroy <%= singular_table_name %>" do
+    assert_difference('<%= class_name %>.count', -1) do
+      delete :destroy, params: { id: <%= "@#{singular_table_name}" %> }
+    end
+
+    assert_response 204
+  end
+end
+<% end -%>
diff --git a/railties/test/application/generators_test.rb b/railties/test/application/generators_test.rb
index 78ada58ec8..84cc6e120b 100644
--- a/railties/test/application/generators_test.rb
+++ b/railties/test/application/generators_test.rb
@@ -125,5 +125,40 @@ module ApplicationTests
         assert_equal expected, c.generators.options
       end
     end
+
+    test "api only generators hide assets, helper, js and css namespaces and set api option" do
+      add_to_config <<-RUBY
+        config.api_only = true
+      RUBY
+
+      # Initialize the application
+      require "#{app_path}/config/environment"
+      Rails.application.load_generators
+
+      assert Rails::Generators.hidden_namespaces.include?("assets")
+      assert Rails::Generators.hidden_namespaces.include?("helper")
+      assert Rails::Generators.hidden_namespaces.include?("js")
+      assert Rails::Generators.hidden_namespaces.include?("css")
+      assert Rails::Generators.options[:rails][:api]
+      assert_equal false, Rails::Generators.options[:rails][:assets]
+      assert_equal false, Rails::Generators.options[:rails][:helper]
+      assert_nil Rails::Generators.options[:rails][:template_engine]
+    end
+
+    test "api only generators allow overriding generator options" do
+      add_to_config <<-RUBY
+      config.generators.helper = true
+      config.api_only = true
+      config.generators.template_engine = :my_template
+      RUBY
+
+      # Initialize the application
+      require "#{app_path}/config/environment"
+      Rails.application.load_generators
+
+      assert Rails::Generators.options[:rails][:api]
+      assert Rails::Generators.options[:rails][:helper]
+      assert_equal :my_template, Rails::Generators.options[:rails][:template_engine]
+    end
   end
 end
diff --git a/railties/test/application/initializers/frameworks_test.rb b/railties/test/application/initializers/frameworks_test.rb
index 97b51911d9..af98e08d0e 100644
--- a/railties/test/application/initializers/frameworks_test.rb
+++ b/railties/test/application/initializers/frameworks_test.rb
@@ -129,6 +129,35 @@ module ApplicationTests
       assert_equal "false", last_response.body
     end
 
+    test "action_controller api executes using all the middleware stack" do
+      add_to_config "config.api_only = true"
+
+      app_file "app/controllers/application_controller.rb", <<-RUBY
+        class ApplicationController < ActionController::API
+        end
+      RUBY
+
+      app_file "app/controllers/omg_controller.rb", <<-RUBY
+        class OmgController < ApplicationController
+          def show
+            render json: { omg: 'omg' }
+          end
+        end
+      RUBY
+
+      app_file "config/routes.rb", <<-RUBY
+        Rails.application.routes.draw do
+          get "/:controller(/:action)"
+        end
+      RUBY
+
+      require 'rack/test'
+      extend Rack::Test::Methods
+
+      get 'omg/show'
+      assert_equal '{"omg":"omg"}', last_response.body
+    end
+
     # AD
     test "action_dispatch extensions are applied to ActionDispatch" do
       add_to_config "config.action_dispatch.tld_length = 2"
diff --git a/railties/test/application/middleware_test.rb b/railties/test/application/middleware_test.rb
index 04bd19784a..ce92ebbf66 100644
--- a/railties/test/application/middleware_test.rb
+++ b/railties/test/application/middleware_test.rb
@@ -50,6 +50,33 @@ module ApplicationTests
       ], middleware
     end
 
+    test "api middleware stack" do
+      add_to_config "config.api_only = true"
+
+      boot!
+
+      assert_equal [
+        "Rack::Sendfile",
+        "ActionDispatch::Static",
+        "Rack::Lock",
+        "ActiveSupport::Cache::Strategy::LocalCache",
+        "Rack::Runtime",
+        "ActionDispatch::RequestId",
+        "Rails::Rack::Logger", # must come after Rack::MethodOverride to properly log overridden methods
+        "ActionDispatch::ShowExceptions",
+        "ActionDispatch::DebugExceptions",
+        "ActionDispatch::RemoteIp",
+        "ActionDispatch::Reloader",
+        "ActionDispatch::Callbacks",
+        "ActiveRecord::ConnectionAdapters::ConnectionManagement",
+        "ActiveRecord::QueryCache",
+        "ActionDispatch::ParamsParser",
+        "Rack::Head",
+        "Rack::ConditionalGet",
+        "Rack::ETag"
+      ], middleware
+    end
+
     test "Rack::Cache is not included by default" do
       boot!
 
diff --git a/railties/test/application/rake_test.rb b/railties/test/application/rake_test.rb
index dd26ec867d..a839a0b9b6 100644
--- a/railties/test/application/rake_test.rb
+++ b/railties/test/application/rake_test.rb
@@ -194,6 +194,25 @@ module ApplicationTests
       assert_no_match(/Errors running/, output)
     end
 
+    def test_api_scaffold_tests_pass_by_default
+      add_to_config <<-RUBY
+        config.api_only = true
+      RUBY
+
+      app_file "app/controllers/application_controller.rb", <<-RUBY
+        class ApplicationController < ActionController::API
+        end
+      RUBY
+
+      output = Dir.chdir(app_path) do
+        `rails generate scaffold user username:string password:string;
+         bundle exec rake db:migrate test`
+      end
+
+      assert_match(/5 runs, 8 assertions, 0 failures, 0 errors/, output)
+      assert_no_match(/Errors running/, output)
+    end
+
     def test_scaffold_with_references_columns_tests_pass_when_belongs_to_is_optional
       app_file "config/initializers/active_record_belongs_to_required_by_default.rb",
         "Rails.application.config.active_record.belongs_to_required_by_default = false"
diff --git a/railties/test/generators/api_app_generator_test.rb b/railties/test/generators/api_app_generator_test.rb
new file mode 100644
index 0000000000..9978ad0da1
--- /dev/null
+++ b/railties/test/generators/api_app_generator_test.rb
@@ -0,0 +1,96 @@
+require 'generators/generators_test_helper'
+require 'rails/generators/rails/app/app_generator'
+
+class ApiAppGeneratorTest < Rails::Generators::TestCase
+  include GeneratorsTestHelper
+  tests Rails::Generators::AppGenerator
+
+  arguments [destination_root, '--api']
+
+  def setup
+    Rails.application = TestApp::Application
+    super
+
+    Kernel::silence_warnings do
+      Thor::Base.shell.send(:attr_accessor, :always_force)
+      @shell = Thor::Base.shell.new
+      @shell.send(:always_force=, true)
+    end
+  end
+
+  def teardown
+    super
+    Rails.application = TestApp::Application.instance
+  end
+
+  def test_skeleton_is_created
+    run_generator
+
+    default_files.each { |path| assert_file path }
+    skipped_files.each { |path| assert_no_file path }
+  end
+
+  def test_api_modified_files
+    run_generator
+
+    assert_file "Gemfile" do |content|
+      assert_no_match(/gem 'coffee-rails'/, content)
+      assert_no_match(/gem 'jquery-rails'/, content)
+      assert_no_match(/gem 'sass-rails'/, content)
+      assert_no_match(/gem 'jbuilder'/, content)
+      assert_match(/gem 'active_model_serializers'/, content)
+    end
+
+    assert_file "config/application.rb" do |content|
+      assert_match(/config.api_only = true/, content)
+    end
+
+    assert_file "config/initializers/cors.rb"
+
+    assert_file "config/initializers/wrap_parameters.rb"
+
+    assert_file "app/controllers/application_controller.rb", /ActionController::API/
+  end
+
+  private
+
+  def default_files
+    files = %W(
+      .gitignore
+      Gemfile
+      Rakefile
+      config.ru
+      app/controllers
+      app/mailers
+      app/models
+      config/environments
+      config/initializers
+      config/locales
+      db
+      lib
+      lib/tasks
+      log
+      test/fixtures
+      test/controllers
+      test/integration
+      test/models
+      tmp
+      vendor
+    )
+    files.concat %w(bin/bundle bin/rails bin/rake)
+    files
+  end
+
+  def skipped_files
+    %w(app/assets
+       app/helpers
+       app/views
+       config/initializers/assets.rb
+       config/initializers/cookies_serializer.rb
+       config/initializers/session_store.rb
+       lib/assets
+       vendor/assets
+       test/helpers
+       tmp/cache/assets)
+  end
+end
diff --git a/railties/test/generators/scaffold_controller_generator_test.rb b/railties/test/generators/scaffold_controller_generator_test.rb
index 7c282377d7..5dae36b65e 100644
--- a/railties/test/generators/scaffold_controller_generator_test.rb
+++ b/railties/test/generators/scaffold_controller_generator_test.rb
@@ -185,4 +185,51 @@ class ScaffoldControllerGeneratorTest < Rails::Generators::TestCase
       assert_match(/2 runs, 2 assertions, 0 failures, 0 errors/, `bundle exec rake test 2>&1`)
     end
   end
+
+  def test_api_only_generates_a_proper_api_controller
+    run_generator ["User", "--api"]
+
+    assert_file "app/controllers/users_controller.rb" do |content|
+      assert_match(/class UsersController < ApplicationController/, content)
+      assert_no_match(/respond_to/, content)
+
+      assert_match(/before_action :set_user, only: \[:show, :update, :destroy\]/, content)
+
+      assert_instance_method :index, content do |m|
+        assert_match(/@users = User\.all/, m)
+        assert_match(/render json: @users/, m)
+      end
+
+      assert_instance_method :show, content do |m|
+        assert_match(/render json: @user/, m)
+      end
+
+      assert_instance_method :create, content do |m|
+        assert_match(/@user = User\.new\(user_params\)/, m)
+        assert_match(/@user\.save/, m)
+        assert_match(/@user\.errors/, m)
+      end
+
+      assert_instance_method :update, content do |m|
+        assert_match(/@user\.update\(user_params\)/, m)
+        assert_match(/@user\.errors/, m)
+      end
+
+      assert_instance_method :destroy, content do |m|
+        assert_match(/@user\.destroy/, m)
+      end
+    end
+  end
+
+  def test_api_controller_tests
+    run_generator ["User", "name:string", "age:integer", "organization:references{polymorphic}", "--api"]
+
+    assert_file "test/controllers/users_controller_test.rb" do |content|
+      assert_match(/class UsersControllerTest < ActionController::TestCase/, content)
+      assert_match(/test "should get index"/, content)
+      assert_match(/post :create, params: \{ user: \{ age: @user\.age, name: @user\.name, organization_id: @user\.organization_id, organization_type: @user\.organization_type \} \}/, content)
+      assert_match(/patch :update, params: \{ id: @user, user: \{ age: @user\.age, name: @user\.name, organization_id: @user\.organization_id, organization_type: @user\.organization_type \} \}/, content)
+      assert_no_match(/assert_redirected_to/, content)
+    end
+  end
 end
diff --git a/railties/test/generators/scaffold_generator_test.rb b/railties/test/generators/scaffold_generator_test.rb
index 8d7fea8741..3401b96d7d 100644
--- a/railties/test/generators/scaffold_generator_test.rb
+++ b/railties/test/generators/scaffold_generator_test.rb
@@ -87,6 +87,76 @@ class ScaffoldGeneratorTest < Rails::Generators::TestCase
     assert_file "app/assets/stylesheets/product_lines.css"
   end
 
+  def test_api_scaffold_on_invoke
+    run_generator %w(product_line title:string product:belongs_to user:references --api --no-template-engine --no-helper --no-assets)
+
+    # Model
+    assert_file "app/models/product_line.rb", /class ProductLine < ActiveRecord::Base/
+    assert_file "test/models/product_line_test.rb", /class ProductLineTest < ActiveSupport::TestCase/
+    assert_file "test/fixtures/product_lines.yml"
+    assert_migration "db/migrate/create_product_lines.rb", /belongs_to :product, index: true/
+    assert_migration "db/migrate/create_product_lines.rb", /references :user, index: true/
+
+    # Route
+    assert_file "config/routes.rb" do |route|
+      assert_match(/resources :product_lines$/, route)
+    end
+
+    # Controller
+    assert_file "app/controllers/product_lines_controller.rb" do |content|
+      assert_match(/class ProductLinesController < ApplicationController/, content)
+      assert_no_match(/respond_to/, content)
+
+      assert_match(/before_action :set_product_line, only: \[:show, :update, :destroy\]/, content)
+
+      assert_instance_method :index, content do |m|
+        assert_match(/@product_lines = ProductLine\.all/, m)
+        assert_match(/render json: @product_lines/, m)
+      end
+
+      assert_instance_method :show, content do |m|
+        assert_match(/render json: @product_line/, m)
+      end
+
+      assert_instance_method :create, content do |m|
+        assert_match(/@product_line = ProductLine\.new\(product_line_params\)/, m)
+        assert_match(/@product_line\.save/, m)
+        assert_match(/@product_line\.errors/, m)
+      end
+
+      assert_instance_method :update, content do |m|
+        assert_match(/@product_line\.update\(product_line_params\)/, m)
+        assert_match(/@product_line\.errors/, m)
+      end
+
+      assert_instance_method :destroy, content do |m|
+        assert_match(/@product_line\.destroy/, m)
+      end
+    end
+
+    assert_file "test/controllers/product_lines_controller_test.rb" do |test|
+      assert_match(/class ProductLinesControllerTest < ActionController::TestCase/, test)
+      assert_match(/post :create, params: \{ product_line: \{ product_id: @product_line\.product_id, title: @product_line\.title, user_id: @product_line\.user_id \} \}/, test)
+      assert_match(/patch :update, params: \{ id: @product_line, product_line: \{ product_id: @product_line\.product_id, title: @product_line\.title, user_id: @product_line\.user_id \} \}/, test)
+      assert_no_match(/assert_redirected_to/, test)
+    end
+
+    # Views
+    assert_no_file "app/views/layouts/product_lines.html.erb"
+
+    %w(index show new edit _form).each do |view|
+      assert_no_file "app/views/product_lines/#{view}.html.erb"
+    end
+
+    # Helpers
+    assert_no_file "app/helpers/product_lines_helper.rb"
+
+    # Assets
+    assert_no_file "app/assets/stylesheets/scaffold.css"
+    assert_no_file "app/assets/javascripts/product_lines.js"
+    assert_no_file "app/assets/stylesheets/product_lines.css"
+  end
+
   def test_functional_tests_without_attributes
     run_generator ["product_line"]