applies new string literal convention in railties/test

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

39 files changed, 858 insertions, 858 deletions

diff --git a/railties/test/application/asset_debugging_test.rb b/railties/test/application/asset_debugging_test.rb
index 19327efcc8..ccecf2c09e 100644
--- a/railties/test/application/asset_debugging_test.rb
+++ b/railties/test/application/asset_debugging_test.rb
@@ -1,5 +1,5 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
+require "isolation/abstract_unit"
+require "rack/test"
 
 module ApplicationTests
   class AssetDebuggingTest < ActiveSupport::TestCase
@@ -51,7 +51,7 @@ module ApplicationTests
       class ::PostsController < ActionController::Base ; end
 
       # the debug_assets params isn't used if compile is off
-      get '/posts?debug_assets=true'
+      get "/posts?debug_assets=true"
       assert_match(/<script src="\/assets\/application-([0-z]+)\.js"><\/script>/, last_response.body)
       assert_no_match(/<script src="\/assets\/xmlhr-([0-z]+)\.js"><\/script>/, last_response.body)
     end
@@ -64,7 +64,7 @@ module ApplicationTests
 
       class ::PostsController < ActionController::Base ; end
 
-      get '/posts?debug_assets=true'
+      get "/posts?debug_assets=true"
       assert_match(/<script src="\/assets\/application(\.self)?-([0-z]+)\.js\?body=1"><\/script>/, last_response.body)
       assert_match(/<script src="\/assets\/xmlhr(\.self)?-([0-z]+)\.js\?body=1"><\/script>/, last_response.body)
     end
diff --git a/railties/test/application/assets_test.rb b/railties/test/application/assets_test.rb
index 20329c6e60..3b5bf7ce87 100644
--- a/railties/test/application/assets_test.rb
+++ b/railties/test/application/assets_test.rb
@@ -1,6 +1,6 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
-require 'active_support/json'
+require "isolation/abstract_unit"
+require "rack/test"
+require "active_support/json"
 
 module ApplicationTests
   class AssetsTest < ActiveSupport::TestCase
@@ -35,7 +35,7 @@ module ApplicationTests
 
     def clean_assets!
       quietly do
-        assert Dir.chdir(app_path) { system('bin/rails assets:clobber') }
+        assert Dir.chdir(app_path) { system("bin/rails assets:clobber") }
       end
     end
 
@@ -52,7 +52,7 @@ module ApplicationTests
       app_file "app/assets/images/rails.png", "notactuallyapng"
       app_file "app/assets/javascripts/demo.js.erb", "a = <%= image_path('rails.png').inspect %>;"
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get '*path', to: lambda { |env| [200, { "Content-Type" => "text/html" }, ["Not an asset"]] }
         end
@@ -110,8 +110,8 @@ module ApplicationTests
       eoruby
 
       precompile! \
-        RAILS_ENV: 'production',
-        DATABASE_URL: 'postgresql://baduser:badpass@127.0.0.1/dbname'
+        RAILS_ENV: "production",
+        DATABASE_URL: "postgresql://baduser:badpass@127.0.0.1/dbname"
 
       files = Dir["#{app_path}/public/assets/application-*.js"]
       files << Dir["#{app_path}/public/assets/foo/application-*.js"].first
@@ -176,19 +176,19 @@ module ApplicationTests
       assert_file_exists("#{app_path}/public/assets/something/index-*.js")
     end
 
-    test 'precompile use assets defined in app env config' do
-      add_to_env_config 'production', 'config.assets.precompile = [ "something.js" ]'
-      app_file 'app/assets/javascripts/something.js.erb', 'alert();'
+    test "precompile use assets defined in app env config" do
+      add_to_env_config "production", 'config.assets.precompile = [ "something.js" ]'
+      app_file "app/assets/javascripts/something.js.erb", "alert();"
 
-      precompile! RAILS_ENV: 'production'
+      precompile! RAILS_ENV: "production"
 
       assert_file_exists("#{app_path}/public/assets/something-*.js")
     end
 
-    test 'sprockets cache is not shared between environments' do
+    test "sprockets cache is not shared between environments" do
       app_file "app/assets/images/rails.png", "notactuallyapng"
       app_file "app/assets/stylesheets/application.css.erb", "body { background: '<%= asset_path('rails.png') %>'; }"
-      add_to_env_config 'production', 'config.assets.prefix = "production_assets"'
+      add_to_env_config "production", 'config.assets.prefix = "production_assets"'
 
       precompile!
 
@@ -197,7 +197,7 @@ module ApplicationTests
       file = Dir["#{app_path}/public/assets/application-*.css"].first
       assert_match(/assets\/rails-([0-z]+)\.png/, File.read(file))
 
-      precompile! RAILS_ENV: 'production'
+      precompile! RAILS_ENV: "production"
 
       assert_file_exists("#{app_path}/public/production_assets/application-*.css")
 
@@ -205,17 +205,17 @@ module ApplicationTests
       assert_match(/production_assets\/rails-([0-z]+)\.png/, File.read(file))
     end
 
-    test 'precompile use assets defined in app config and reassigned in app env config' do
+    test "precompile use assets defined in app config and reassigned in app env config" do
       add_to_config 'config.assets.precompile = [ "something_manifest.js" ]'
-      add_to_env_config 'production', 'config.assets.precompile += [ "another_manifest.js" ]'
+      add_to_env_config "production", 'config.assets.precompile += [ "another_manifest.js" ]'
 
-      app_file 'app/assets/config/something_manifest.js', '//= link something.js'
-      app_file 'app/assets/config/another_manifest.js', '//= link another.js'
+      app_file "app/assets/config/something_manifest.js", "//= link something.js"
+      app_file "app/assets/config/another_manifest.js", "//= link another.js"
 
-      app_file 'app/assets/javascripts/something.js.erb', 'alert();'
-      app_file 'app/assets/javascripts/another.js.erb', 'alert();'
+      app_file "app/assets/javascripts/something.js.erb", "alert();"
+      app_file "app/assets/javascripts/another.js.erb", "alert();"
 
-      precompile! RAILS_ENV: 'production'
+      precompile! RAILS_ENV: "production"
 
       assert_file_exists("#{app_path}/public/assets/something_manifest-*.js")
       assert_file_exists("#{app_path}/public/assets/something-*.js")
@@ -261,7 +261,7 @@ module ApplicationTests
       app_file "app/assets/javascripts/application.js", "alert();"
       add_to_env_config "production", "config.public_file_server.enabled = true"
 
-      precompile! RAILS_ENV: 'production'
+      precompile! RAILS_ENV: "production"
 
       manifest = Dir["#{app_path}/public/assets/.sprockets-manifest-*.json"].first
       assets = ActiveSupport::JSON.decode(File.read(manifest))
@@ -292,7 +292,7 @@ module ApplicationTests
 
       app_file "app/assets/stylesheets/application.css.erb", "p { background-image: url(<%= asset_path('rails.png') %>) }"
 
-      precompile! RAILS_ENV: 'production'
+      precompile! RAILS_ENV: "production"
 
       manifest = Dir["#{app_path}/public/assets/.sprockets-manifest-*.json"].first
       assets = ActiveSupport::JSON.decode(File.read(manifest))
@@ -310,7 +310,7 @@ module ApplicationTests
       app_file "app/assets/images/rails.png", "notactuallyapng"
       app_file "app/assets/stylesheets/application.css.erb", "p { background-image: url(<%= asset_path('rails.png') %>) }"
 
-      precompile! RAILS_ENV: 'production'
+      precompile! RAILS_ENV: "production"
 
       file = Dir["#{app_path}/public/assets/application-*.css"].first
       assert_match(/\/assets\/rails-([0-z]+)\.png/, File.read(file))
@@ -380,7 +380,7 @@ module ApplicationTests
       end
 
       get "/omg"
-      assert_equal 'ok', last_response.body
+      assert_equal "ok", last_response.body
 
       get "/assets/demo.js"
       assert_match "alert()", last_response.body
@@ -408,7 +408,7 @@ module ApplicationTests
       app_with_assets_in_view
 
       # config.assets.debug and config.assets.compile are false for production environment
-      precompile! RAILS_ENV: 'production'
+      precompile! RAILS_ENV: "production"
 
       # Load app env
       app "production"
@@ -416,7 +416,7 @@ module ApplicationTests
       class ::PostsController < ActionController::Base ; end
 
       # the debug_assets params isn't used if compile is off
-      get '/posts?debug_assets=true'
+      get "/posts?debug_assets=true"
       assert_match(/<script src="\/assets\/application-([0-z]+)\.js"><\/script>/, last_response.body)
       assert_no_match(/<script src="\/assets\/xmlhr-([0-z]+)\.js"><\/script>/, last_response.body)
     end
@@ -475,9 +475,9 @@ module ApplicationTests
 
       class ::PostsController < ActionController::Base; end
 
-      get '/posts', {}, {'HTTPS'=>'off'}
+      get "/posts", {}, {"HTTPS"=>"off"}
       assert_match('src="http://example.com/assets/application.self.js', last_response.body)
-      get '/posts', {}, {'HTTPS'=>'on'}
+      get "/posts", {}, {"HTTPS"=>"on"}
       assert_match('src="https://example.com/assets/application.self.js', last_response.body)
     end
 
diff --git a/railties/test/application/bin_setup_test.rb b/railties/test/application/bin_setup_test.rb
index ba700df1d6..2f076ea2f6 100644
--- a/railties/test/application/bin_setup_test.rb
+++ b/railties/test/application/bin_setup_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class BinSetupTest < ActiveSupport::TestCase
@@ -14,7 +14,7 @@ module ApplicationTests
 
     def test_bin_setup
       Dir.chdir(app_path) do
-        app_file 'db/schema.rb', <<-RUBY
+        app_file "db/schema.rb", <<-RUBY
           ActiveRecord::Schema.define(version: 20140423102712) do
             create_table(:articles) {}
           end
@@ -23,7 +23,7 @@ module ApplicationTests
         list_tables = lambda { `bin/rails runner 'p ActiveRecord::Base.connection.tables'`.strip }
         File.write("log/test.log", "zomg!")
 
-        assert_equal '[]', list_tables.call
+        assert_equal "[]", list_tables.call
         assert_equal 5, File.size("log/test.log")
         assert_not File.exist?("tmp/restart.txt")
         `bin/setup 2>&1`
@@ -35,7 +35,7 @@ module ApplicationTests
 
     def test_bin_setup_output
       Dir.chdir(app_path) do
-        app_file 'db/schema.rb', ""
+        app_file "db/schema.rb", ""
 
         output = `bin/setup 2>&1`
         assert_equal(<<-OUTPUT, output)
diff --git a/railties/test/application/configuration/custom_test.rb b/railties/test/application/configuration/custom_test.rb
index 677cb8328c..13fc98f0d6 100644
--- a/railties/test/application/configuration/custom_test.rb
+++ b/railties/test/application/configuration/custom_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   module ConfigurationTests
@@ -13,7 +13,7 @@ module ApplicationTests
         FileUtils.rm_rf(new_app) if File.directory?(new_app)
       end
 
-      test 'access custom configuration point' do
+      test "access custom configuration point" do
         add_to_config <<-RUBY
           config.x.payment_processing.schedule = :daily
           config.x.payment_processing.retries  = 3
@@ -32,7 +32,7 @@ module ApplicationTests
         assert_nil x.i_do_not_exist.zomg
       end
 
-      test 'custom configuration responds to all messages' do
+      test "custom configuration responds to all messages" do
         x = Rails.configuration.x
         assert_equal true, x.respond_to?(:i_do_not_exist)
         assert_kind_of Method, x.method(:i_do_not_exist)
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index e4a3adee9f..01bdcfb9aa 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -1,6 +1,6 @@
 require "isolation/abstract_unit"
-require 'rack/test'
-require 'env_helpers'
+require "rack/test"
+require "env_helpers"
 
 class ::MyMailInterceptor
   def self.delivering_email(email); email; end
@@ -34,9 +34,9 @@ module ApplicationTests
       FileUtils.cp_r(app_path, new_app)
     end
 
-    def app(env = 'development')
+    def app(env = "development")
       @app ||= begin
-        ENV['RAILS_ENV'] = env
+        ENV["RAILS_ENV"] = env
 
         # FIXME: shush Sass warning spam, not relevant to testing Railties
         Kernel.silence_warnings do
@@ -45,7 +45,7 @@ module ApplicationTests
 
         Rails.application
       ensure
-        ENV.delete 'RAILS_ENV'
+        ENV.delete "RAILS_ENV"
       end
     end
 
@@ -74,7 +74,7 @@ module ApplicationTests
       switch_env "RAILS_ENV", nil do
         Rails.env = "development"
         assert_equal "development", Rails.env
-        assert_nil ENV['RAILS_ENV']
+        assert_nil ENV["RAILS_ENV"]
       end
     end
 
@@ -82,7 +82,7 @@ module ApplicationTests
       restore_default_config
 
       with_rails_env "development" do
-        app 'development'
+        app "development"
         assert Rails.application.config.log_tags.blank?
       end
     end
@@ -91,13 +91,13 @@ module ApplicationTests
       restore_default_config
 
       with_rails_env "production" do
-        app 'production'
+        app "production"
         assert_equal [:request_id], Rails.application.config.log_tags
       end
     end
 
     test "lib dir is on LOAD_PATH during config" do
-      app_file 'lib/my_logger.rb', <<-RUBY
+      app_file "lib/my_logger.rb", <<-RUBY
         require "logger"
         class MyLogger < ::Logger
         end
@@ -107,9 +107,9 @@ module ApplicationTests
         config.logger = MyLogger.new STDOUT
       RUBY
 
-      app 'development'
+      app "development"
 
-      assert_equal 'MyLogger', Rails.application.config.logger.class.name
+      assert_equal "MyLogger", Rails.application.config.logger.class.name
     end
 
     test "a renders exception on pending migration" do
@@ -119,7 +119,7 @@ module ApplicationTests
         config.action_dispatch.show_exceptions  = true
       RUBY
 
-      app_file 'db/migrate/20140708012246_create_user.rb', <<-RUBY
+      app_file "db/migrate/20140708012246_create_user.rb", <<-RUBY
         class CreateUser < ActiveRecord::Migration::Current
           def change
             create_table :users
@@ -127,7 +127,7 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
 
       ActiveRecord::Migrator.migrations_paths = ["#{app_path}/db/migrate"]
 
@@ -156,31 +156,31 @@ module ApplicationTests
     end
 
     test "Rails.application is nil until app is initialized" do
-      require 'rails'
+      require "rails"
       assert_nil Rails.application
-      app 'development'
+      app "development"
       assert_equal AppTemplate::Application.instance, Rails.application
     end
 
     test "Rails.application responds to all instance methods" do
-      app 'development'
+      app "development"
       assert_respond_to Rails.application, :routes_reloader
       assert_equal Rails.application.routes_reloader, AppTemplate::Application.routes_reloader
     end
 
     test "Rails::Application responds to paths" do
-      app 'development'
+      app "development"
       assert_respond_to AppTemplate::Application, :paths
       assert_equal ["#{app_path}/app/views"], AppTemplate::Application.paths["app/views"].expanded
     end
 
     test "the application root is set correctly" do
-      app 'development'
+      app "development"
       assert_equal Pathname.new(app_path), Rails.application.root
     end
 
     test "the application root can be seen from the application singleton" do
-      app 'development'
+      app "development"
       assert_equal Pathname.new(app_path), AppTemplate::Application.root
     end
 
@@ -192,7 +192,7 @@ module ApplicationTests
 
       use_frameworks []
 
-      app 'development'
+      app "development"
 
       assert_equal Pathname.new(new_app), Rails.application.root
     end
@@ -203,7 +203,7 @@ module ApplicationTests
       use_frameworks []
 
       Dir.chdir("#{app_path}") do
-        app 'development'
+        app "development"
         assert_equal Pathname.new("#{app_path}"), Rails.application.root
       end
     end
@@ -213,7 +213,7 @@ module ApplicationTests
         config.root = "#{app_path}"
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_instance_of Pathname, Rails.root
     end
@@ -223,7 +223,7 @@ module ApplicationTests
         config.paths["public"] = "somewhere"
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_instance_of Pathname, Rails.public_path
     end
@@ -234,13 +234,13 @@ module ApplicationTests
         config.cache_classes = true
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal :require, ActiveSupport::Dependencies.mechanism
     end
 
     test "application is always added to eager_load namespaces" do
-      app 'development'
+      app "development"
       assert_includes Rails.application.config.eager_load_namespaces, AppTemplate::Application
     end
 
@@ -256,7 +256,7 @@ module ApplicationTests
       use_frameworks []
 
       assert_nothing_raised do
-        app 'development'
+        app "development"
       end
     end
 
@@ -268,18 +268,18 @@ module ApplicationTests
       RUBY
 
       assert_nothing_raised do
-        app 'development'
+        app "development"
       end
     end
 
     test "filter_parameters should be able to set via config.filter_parameters in an initializer" do
-      app_file 'config/initializers/filter_parameters_logging.rb', <<-RUBY
+      app_file "config/initializers/filter_parameters_logging.rb", <<-RUBY
         Rails.application.config.filter_parameters += [ :password, :foo, 'bar' ]
       RUBY
 
-      app 'development'
+      app "development"
 
-      assert_equal [:password, :foo, 'bar'], Rails.application.env_config['action_dispatch.parameter_filter']
+      assert_equal [:password, :foo, "bar"], Rails.application.env_config["action_dispatch.parameter_filter"]
     end
 
     test "config.to_prepare is forwarded to ActionDispatch" do
@@ -293,7 +293,7 @@ module ApplicationTests
 
       assert !$prepared
 
-      app 'development'
+      app "development"
 
       get "/"
       assert $prepared
@@ -305,7 +305,7 @@ module ApplicationTests
     end
 
     test "skipping config.encoding still results in 'utf-8' as the default" do
-      app 'development'
+      app "development"
       assert_utf8
     end
 
@@ -314,7 +314,7 @@ module ApplicationTests
         config.encoding = "utf-8"
       RUBY
 
-      app 'development'
+      app "development"
       assert_utf8
     end
 
@@ -323,7 +323,7 @@ module ApplicationTests
         config.paths["public"] = "somewhere"
       RUBY
 
-      app 'development'
+      app "development"
       assert_equal Pathname.new(app_path).join("somewhere"), Rails.public_path
     end
 
@@ -331,7 +331,7 @@ module ApplicationTests
       restore_default_config
 
       with_rails_env "production" do
-        app 'production'
+        app "production"
         assert_not app.config.public_file_server.enabled
       end
     end
@@ -341,7 +341,7 @@ module ApplicationTests
 
       with_rails_env "production" do
         switch_env "RAILS_SERVE_STATIC_FILES", "1" do
-          app 'production'
+          app "production"
           assert app.config.public_file_server.enabled
         end
       end
@@ -352,7 +352,7 @@ module ApplicationTests
 
       with_rails_env "production" do
         switch_env "RAILS_LOG_TO_STDOUT", "1" do
-          app 'production'
+          app "production"
           assert ActiveSupport::Logger.logger_outputs_to?(app.config.logger, STDOUT)
         end
       end
@@ -363,7 +363,7 @@ module ApplicationTests
 
       with_rails_env "production" do
         switch_env "RAILS_SERVE_STATIC_FILES", " " do
-          app 'production'
+          app "production"
           assert_not app.config.public_file_server.enabled
         end
       end
@@ -391,7 +391,7 @@ module ApplicationTests
 
     test "Use key_generator when secret_key_base is set" do
       make_basic_app do |application|
-        application.secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
+        application.secrets.secret_key_base = "b3c631c314c0bbca50c1b2843150fe33"
         application.config.session_store :disabled
       end
 
@@ -404,53 +404,53 @@ module ApplicationTests
 
       get "/"
 
-      secret = app.key_generator.generate_key('signed cookie')
+      secret = app.key_generator.generate_key("signed cookie")
       verifier = ActiveSupport::MessageVerifier.new(secret)
-      assert_equal 'some_value', verifier.verify(last_response.body)
+      assert_equal "some_value", verifier.verify(last_response.body)
     end
 
     test "application verifier can be used in the entire application" do
       make_basic_app do |application|
-        application.secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
+        application.secrets.secret_key_base = "b3c631c314c0bbca50c1b2843150fe33"
         application.config.session_store :disabled
       end
 
       message = app.message_verifier(:sensitive_value).generate("some_value")
 
-      assert_equal 'some_value', Rails.application.message_verifier(:sensitive_value).verify(message)
+      assert_equal "some_value", Rails.application.message_verifier(:sensitive_value).verify(message)
 
-      secret = app.key_generator.generate_key('sensitive_value')
+      secret = app.key_generator.generate_key("sensitive_value")
       verifier = ActiveSupport::MessageVerifier.new(secret)
-      assert_equal 'some_value', verifier.verify(message)
+      assert_equal "some_value", verifier.verify(message)
     end
 
     test "application message verifier can be used when the key_generator is ActiveSupport::LegacyKeyGenerator" do
-      app_file 'config/initializers/secret_token.rb', <<-RUBY
+      app_file "config/initializers/secret_token.rb", <<-RUBY
         Rails.application.config.secret_token = "b3c631c314c0bbca50c1b2843150fe33"
       RUBY
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base:
       YAML
 
-      app 'development'
+      app "development"
 
-      assert_equal app.env_config['action_dispatch.key_generator'], Rails.application.key_generator
-      assert_equal app.env_config['action_dispatch.key_generator'].class, ActiveSupport::LegacyKeyGenerator
+      assert_equal app.env_config["action_dispatch.key_generator"], Rails.application.key_generator
+      assert_equal app.env_config["action_dispatch.key_generator"].class, ActiveSupport::LegacyKeyGenerator
       message = app.message_verifier(:sensitive_value).generate("some_value")
-      assert_equal 'some_value', Rails.application.message_verifier(:sensitive_value).verify(message)
+      assert_equal "some_value", Rails.application.message_verifier(:sensitive_value).verify(message)
     end
 
     test "warns when secrets.secret_key_base is blank and config.secret_token is set" do
-      app_file 'config/initializers/secret_token.rb', <<-RUBY
+      app_file "config/initializers/secret_token.rb", <<-RUBY
         Rails.application.config.secret_token = "b3c631c314c0bbca50c1b2843150fe33"
       RUBY
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base:
       YAML
 
-      app 'development'
+      app "development"
 
       assert_deprecated(/You didn't set `secret_key_base`./) do
         app.env_config
@@ -458,12 +458,12 @@ module ApplicationTests
     end
 
     test "raise when secrets.secret_key_base is not a type of string" do
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base: 123
       YAML
 
-      app 'development'
+      app "development"
 
       assert_raise(ArgumentError) do
         app.key_generator
@@ -471,31 +471,31 @@ module ApplicationTests
     end
 
     test "prefer secrets.secret_token over config.secret_token" do
-      app_file 'config/initializers/secret_token.rb', <<-RUBY
+      app_file "config/initializers/secret_token.rb", <<-RUBY
         Rails.application.config.secret_token = ""
       RUBY
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_token: 3b7cd727ee24e8444053437c36cc66c3
       YAML
 
-      app 'development'
+      app "development"
 
-      assert_equal '3b7cd727ee24e8444053437c36cc66c3', app.secrets.secret_token
+      assert_equal "3b7cd727ee24e8444053437c36cc66c3", app.secrets.secret_token
     end
 
     test "application verifier can build different verifiers" do
       make_basic_app do |application|
-        application.secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'
+        application.secrets.secret_key_base = "b3c631c314c0bbca50c1b2843150fe33"
         application.config.session_store :disabled
       end
 
       default_verifier = app.message_verifier(:sensitive_value)
       text_verifier = app.message_verifier(:text)
 
-      message = text_verifier.generate('some_value')
+      message = text_verifier.generate("some_value")
 
-      assert_equal 'some_value', text_verifier.verify(message)
+      assert_equal "some_value", text_verifier.verify(message)
       assert_raises ActiveSupport::MessageVerifier::InvalidSignature do
         default_verifier.verify(message)
       end
@@ -505,68 +505,68 @@ module ApplicationTests
     end
 
     test "secrets.secret_key_base is used when config/secrets.yml is present" do
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base: 3b7cd727ee24e8444053437c36cc66c3
       YAML
 
-      app 'development'
-      assert_equal '3b7cd727ee24e8444053437c36cc66c3', app.secrets.secret_key_base
+      app "development"
+      assert_equal "3b7cd727ee24e8444053437c36cc66c3", app.secrets.secret_key_base
     end
 
     test "secret_key_base is copied from config to secrets when not set" do
       remove_file "config/secrets.yml"
-      app_file 'config/initializers/secret_token.rb', <<-RUBY
+      app_file "config/initializers/secret_token.rb", <<-RUBY
         Rails.application.config.secret_key_base = "3b7cd727ee24e8444053437c36cc66c3"
       RUBY
 
-      app 'development'
-      assert_equal '3b7cd727ee24e8444053437c36cc66c3', app.secrets.secret_key_base
+      app "development"
+      assert_equal "3b7cd727ee24e8444053437c36cc66c3", app.secrets.secret_key_base
     end
 
     test "config.secret_token over-writes a blank secrets.secret_token" do
-      app_file 'config/initializers/secret_token.rb', <<-RUBY
+      app_file "config/initializers/secret_token.rb", <<-RUBY
         Rails.application.config.secret_token = "b3c631c314c0bbca50c1b2843150fe33"
       RUBY
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base:
           secret_token:
       YAML
 
-      app 'development'
+      app "development"
 
-      assert_equal 'b3c631c314c0bbca50c1b2843150fe33', app.secrets.secret_token
-      assert_equal 'b3c631c314c0bbca50c1b2843150fe33', app.config.secret_token
+      assert_equal "b3c631c314c0bbca50c1b2843150fe33", app.secrets.secret_token
+      assert_equal "b3c631c314c0bbca50c1b2843150fe33", app.config.secret_token
     end
 
     test "custom secrets saved in config/secrets.yml are loaded in app secrets" do
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base: 3b7cd727ee24e8444053437c36cc66c3
           aws_access_key_id: myamazonaccesskeyid
           aws_secret_access_key: myamazonsecretaccesskey
       YAML
 
-      app 'development'
+      app "development"
 
-      assert_equal 'myamazonaccesskeyid', app.secrets.aws_access_key_id
-      assert_equal 'myamazonsecretaccesskey', app.secrets.aws_secret_access_key
+      assert_equal "myamazonaccesskeyid", app.secrets.aws_access_key_id
+      assert_equal "myamazonsecretaccesskey", app.secrets.aws_secret_access_key
     end
 
     test "shared secrets saved in config/secrets.yml are loaded in app secrets" do
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         shared:
           api_key: 3b7cd727
       YAML
 
-      app 'development'
+      app "development"
 
-      assert_equal '3b7cd727', app.secrets.api_key
+      assert_equal "3b7cd727", app.secrets.api_key
     end
 
     test "shared secrets will yield to environment specific secrets" do
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         shared:
           api_key: 3b7cd727
 
@@ -574,62 +574,62 @@ module ApplicationTests
           api_key: abc12345
       YAML
 
-      app 'development'
+      app "development"
 
-      assert_equal 'abc12345', app.secrets.api_key
+      assert_equal "abc12345", app.secrets.api_key
     end
 
     test "blank config/secrets.yml does not crash the loading process" do
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
       YAML
 
-      app 'development'
+      app "development"
 
       assert_nil app.secrets.not_defined
     end
 
     test "config.secret_key_base over-writes a blank secrets.secret_key_base" do
-      app_file 'config/initializers/secret_token.rb', <<-RUBY
+      app_file "config/initializers/secret_token.rb", <<-RUBY
         Rails.application.config.secret_key_base = "iaminallyoursecretkeybase"
       RUBY
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base:
       YAML
 
-      app 'development'
+      app "development"
 
       assert_equal "iaminallyoursecretkeybase", app.secrets.secret_key_base
     end
 
     test "uses ActiveSupport::LegacyKeyGenerator as app.key_generator when secrets.secret_key_base is blank" do
-      app_file 'config/initializers/secret_token.rb', <<-RUBY
+      app_file "config/initializers/secret_token.rb", <<-RUBY
         Rails.application.config.secret_token = "b3c631c314c0bbca50c1b2843150fe33"
       RUBY
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base:
       YAML
 
-      app 'development'
+      app "development"
 
-      assert_equal 'b3c631c314c0bbca50c1b2843150fe33', app.config.secret_token
+      assert_equal "b3c631c314c0bbca50c1b2843150fe33", app.config.secret_token
       assert_equal nil, app.secrets.secret_key_base
       assert_equal app.key_generator.class, ActiveSupport::LegacyKeyGenerator
     end
 
     test "uses ActiveSupport::LegacyKeyGenerator with config.secret_token as app.key_generator when secrets.secret_key_base is blank" do
-      app_file 'config/initializers/secret_token.rb', <<-RUBY
+      app_file "config/initializers/secret_token.rb", <<-RUBY
         Rails.application.config.secret_token = ""
       RUBY
-      app_file 'config/secrets.yml', <<-YAML
+      app_file "config/secrets.yml", <<-YAML
         development:
           secret_key_base:
       YAML
 
-      app 'development'
+      app "development"
 
-      assert_equal '', app.config.secret_token
+      assert_equal "", app.config.secret_token
       assert_equal nil, app.secrets.secret_key_base
       assert_raise ArgumentError, /\AA secret is required/ do
         app.key_generator
@@ -650,7 +650,7 @@ module ApplicationTests
     end
 
     test "default form builder specified as a string" do
-      app_file 'config/initializers/form_builder.rb', <<-RUBY
+      app_file "config/initializers/form_builder.rb", <<-RUBY
       class CustomFormBuilder < ActionView::Helpers::FormBuilder
         def text_field(attribute, *args)
           label(attribute) + super(attribute, *args)
@@ -659,7 +659,7 @@ module ApplicationTests
       Rails.configuration.action_view.default_form_builder = "CustomFormBuilder"
       RUBY
 
-      app_file 'app/models/post.rb', <<-RUBY
+      app_file "app/models/post.rb", <<-RUBY
       class Post
         include ActiveModel::Model
         attr_accessor :name
@@ -667,7 +667,7 @@ module ApplicationTests
       RUBY
 
 
-      app_file 'app/controllers/posts_controller.rb', <<-RUBY
+      app_file "app/controllers/posts_controller.rb", <<-RUBY
       class PostsController < ApplicationController
         def index
           render inline: "<%= begin; form_for(Post.new) {|f| f.text_field(:name)}; rescue => e; e.to_s; end %>"
@@ -681,14 +681,14 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
 
       get "/posts"
       assert_match(/label/, last_response.body)
     end
 
     test "default method for update can be changed" do
-      app_file 'app/models/post.rb', <<-RUBY
+      app_file "app/models/post.rb", <<-RUBY
       class Post
         include ActiveModel::Model
         def to_key; [1]; end
@@ -698,7 +698,7 @@ module ApplicationTests
 
       token = "cf50faa3fe97702ca1ae"
 
-      app_file 'app/controllers/posts_controller.rb', <<-RUBY
+      app_file "app/controllers/posts_controller.rb", <<-RUBY
       class PostsController < ApplicationController
         def show
           render inline: "<%= begin; form_for(Post.new) {}; rescue => e; e.to_s; end %>"
@@ -720,7 +720,7 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
 
       params = { authenticity_token: token }
 
@@ -742,7 +742,7 @@ module ApplicationTests
 
     test "request forgery token param can be changed" do
       make_basic_app do |application|
-        application.config.action_controller.request_forgery_protection_token = '_xsrf_token_here'
+        application.config.action_controller.request_forgery_protection_token = "_xsrf_token_here"
       end
 
       class ::OmgController < ActionController::Base
@@ -773,7 +773,7 @@ module ApplicationTests
         config.action_mailer.interceptors = MyMailInterceptor
       RUBY
 
-      app 'development'
+      app "development"
 
       require "mail"
       _ = ActionMailer::Base
@@ -786,7 +786,7 @@ module ApplicationTests
         config.action_mailer.interceptors = [MyMailInterceptor, "MyOtherMailInterceptor"]
       RUBY
 
-      app 'development'
+      app "development"
 
       require "mail"
       _ = ActionMailer::Base
@@ -799,7 +799,7 @@ module ApplicationTests
         config.action_mailer.preview_interceptors = MyPreviewMailInterceptor
       RUBY
 
-      app 'development'
+      app "development"
 
       require "mail"
       _ = ActionMailer::Base
@@ -812,7 +812,7 @@ module ApplicationTests
         config.action_mailer.preview_interceptors = [MyPreviewMailInterceptor, "MyOtherPreviewMailInterceptor"]
       RUBY
 
-      app 'development'
+      app "development"
 
       require "mail"
       _ = ActionMailer::Base
@@ -821,11 +821,11 @@ module ApplicationTests
     end
 
     test "default preview interceptor can be removed" do
-      app_file 'config/initializers/preview_interceptors.rb', <<-RUBY
+      app_file "config/initializers/preview_interceptors.rb", <<-RUBY
         ActionMailer::Base.preview_interceptors.delete(ActionMailer::InlinePreviewInterceptor)
       RUBY
 
-      app 'development'
+      app "development"
 
       require "mail"
       _ = ActionMailer::Base
@@ -838,7 +838,7 @@ module ApplicationTests
         config.action_mailer.observers = MyMailObserver
       RUBY
 
-      app 'development'
+      app "development"
 
       require "mail"
       _ = ActionMailer::Base
@@ -851,7 +851,7 @@ module ApplicationTests
         config.action_mailer.observers = [MyMailObserver, "MyOtherMailObserver"]
       RUBY
 
-      app 'development'
+      app "development"
 
       require "mail"
       _ = ActionMailer::Base
@@ -864,12 +864,12 @@ module ApplicationTests
         config.action_mailer.deliver_later_queue_name = 'test_default'
       RUBY
 
-      app 'development'
+      app "development"
 
       require "mail"
       _ = ActionMailer::Base
 
-      assert_equal 'test_default', ActionMailer::Base.class_variable_get(:@@deliver_later_queue_name)
+      assert_equal "test_default", ActionMailer::Base.class_variable_get(:@@deliver_later_queue_name)
     end
 
     test "valid timezone is setup correctly" do
@@ -878,7 +878,7 @@ module ApplicationTests
         config.time_zone = "Wellington"
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal "Wellington", Rails.application.config.time_zone
     end
@@ -890,7 +890,7 @@ module ApplicationTests
       RUBY
 
       assert_raise(ArgumentError) do
-        app 'development'
+        app "development"
       end
     end
 
@@ -900,7 +900,7 @@ module ApplicationTests
         config.beginning_of_week = :wednesday
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal :wednesday, Rails.application.config.beginning_of_week
     end
@@ -912,15 +912,15 @@ module ApplicationTests
       RUBY
 
       assert_raise(ArgumentError) do
-        app 'development'
+        app "development"
       end
     end
 
     test "config.action_view.cache_template_loading with cache_classes default" do
       add_to_config "config.cache_classes = true"
 
-      app 'development'
-      require 'action_view/base'
+      app "development"
+      require "action_view/base"
 
       assert_equal true, ActionView::Resolver.caching?
     end
@@ -928,8 +928,8 @@ module ApplicationTests
     test "config.action_view.cache_template_loading without cache_classes default" do
       add_to_config "config.cache_classes = false"
 
-      app 'development'
-      require 'action_view/base'
+      app "development"
+      require "action_view/base"
 
       assert_equal false, ActionView::Resolver.caching?
     end
@@ -940,8 +940,8 @@ module ApplicationTests
         config.action_view.cache_template_loading = false
       RUBY
 
-      app 'development'
-      require 'action_view/base'
+      app "development"
+      require "action_view/base"
 
       assert_equal false, ActionView::Resolver.caching?
     end
@@ -952,8 +952,8 @@ module ApplicationTests
         config.action_view.cache_template_loading = true
       RUBY
 
-      app 'development'
-      require 'action_view/base'
+      app "development"
+      require "action_view/base"
 
       assert_equal true, ActionView::Resolver.caching?
     end
@@ -963,11 +963,11 @@ module ApplicationTests
       add_to_env_config "development", "config.cache_classes = false"
 
       # These requires are to emulate an engine loading Action View before the application
-      require 'action_view'
-      require 'action_view/railtie'
-      require 'action_view/base'
+      require "action_view"
+      require "action_view/railtie"
+      require "action_view/base"
 
-      app 'development'
+      app "development"
 
       assert_equal false, ActionView::Resolver.caching?
     end
@@ -984,15 +984,15 @@ module ApplicationTests
       end
 
       get "/"
-      assert_equal 'true', last_response.body
+      assert_equal "true", last_response.body
     end
 
     test "config.action_controller.wrap_parameters is set in ActionController::Base" do
-      app_file 'config/initializers/wrap_parameters.rb', <<-RUBY
+      app_file "config/initializers/wrap_parameters.rb", <<-RUBY
         ActionController::Base.wrap_parameters format: [:json]
       RUBY
 
-      app_file 'app/models/post.rb', <<-RUBY
+      app_file "app/models/post.rb", <<-RUBY
       class Post
         def self.attribute_names
           %w(title)
@@ -1000,13 +1000,13 @@ module ApplicationTests
       end
       RUBY
 
-      app_file 'app/controllers/application_controller.rb', <<-RUBY
+      app_file "app/controllers/application_controller.rb", <<-RUBY
       class ApplicationController < ActionController::Base
         protect_from_forgery with: :reset_session # as we are testing API here
       end
       RUBY
 
-      app_file 'app/controllers/posts_controller.rb', <<-RUBY
+      app_file "app/controllers/posts_controller.rb", <<-RUBY
       class PostsController < ApplicationController
         def create
           render text: params[:post].inspect
@@ -1020,14 +1020,14 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
 
       post "/posts.json", '{ "title": "foo", "name": "bar" }', "CONTENT_TYPE" => "application/json"
       assert_equal '<ActionController::Parameters {"title"=>"foo"} permitted: false>', last_response.body
     end
 
     test "config.action_controller.permit_all_parameters = true" do
-      app_file 'app/controllers/posts_controller.rb', <<-RUBY
+      app_file "app/controllers/posts_controller.rb", <<-RUBY
       class PostsController < ActionController::Base
         def create
           render text: params[:post].permitted? ? "permitted" : "forbidden"
@@ -1042,14 +1042,14 @@ module ApplicationTests
         config.action_controller.permit_all_parameters = true
       RUBY
 
-      app 'development'
+      app "development"
 
       post "/posts", {post: {"title" =>"zomg"}}
-      assert_equal 'permitted', last_response.body
+      assert_equal "permitted", last_response.body
     end
 
     test "config.action_controller.action_on_unpermitted_parameters = :raise" do
-      app_file 'app/controllers/posts_controller.rb', <<-RUBY
+      app_file "app/controllers/posts_controller.rb", <<-RUBY
       class PostsController < ActionController::Base
         def create
           render text: params.require(:post).permit(:name)
@@ -1064,7 +1064,7 @@ module ApplicationTests
         config.action_controller.action_on_unpermitted_parameters = :raise
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal :raise, ActionController::Parameters.action_on_unpermitted_parameters
 
@@ -1073,7 +1073,7 @@ module ApplicationTests
     end
 
     test "config.action_controller.always_permitted_parameters are: controller, action by default" do
-      app 'development'
+      app "development"
       assert_equal %w(controller action), ActionController::Parameters.always_permitted_parameters
     end
 
@@ -1082,13 +1082,13 @@ module ApplicationTests
         config.action_controller.always_permitted_parameters = %w( controller action format )
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal %w( controller action format ), ActionController::Parameters.always_permitted_parameters
     end
 
     test "config.action_controller.always_permitted_parameters = ['controller','action','format'] does not raise exception" do
-      app_file 'app/controllers/posts_controller.rb', <<-RUBY
+      app_file "app/controllers/posts_controller.rb", <<-RUBY
       class PostsController < ActionController::Base
         def create
           render text: params.permit(post: [:title])
@@ -1104,7 +1104,7 @@ module ApplicationTests
         config.action_controller.action_on_unpermitted_parameters = :raise
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal :raise, ActionController::Parameters.action_on_unpermitted_parameters
 
@@ -1113,19 +1113,19 @@ module ApplicationTests
     end
 
     test "config.action_controller.action_on_unpermitted_parameters is :log by default on development" do
-      app 'development'
+      app "development"
 
       assert_equal :log, ActionController::Parameters.action_on_unpermitted_parameters
     end
 
     test "config.action_controller.action_on_unpermitted_parameters is :log by default on test" do
-      app 'test'
+      app "test"
 
       assert_equal :log, ActionController::Parameters.action_on_unpermitted_parameters
     end
 
     test "config.action_controller.action_on_unpermitted_parameters is false by default on production" do
-      app 'production'
+      app "production"
 
       assert_equal false, ActionController::Parameters.action_on_unpermitted_parameters
     end
@@ -1145,21 +1145,21 @@ module ApplicationTests
       end
 
       get "/", {}, "HTTP_ACCEPT" => "application/xml"
-      assert_equal 'HTML', last_response.body
+      assert_equal "HTML", last_response.body
 
       get "/", { format: :xml }, "HTTP_ACCEPT" => "application/xml"
-      assert_equal 'XML', last_response.body
+      assert_equal "XML", last_response.body
     end
 
     test "Rails.application#env_config exists and include some existing parameters" do
       make_basic_app
 
       assert_respond_to app, :env_config
-      assert_equal      app.env_config['action_dispatch.parameter_filter'],  app.config.filter_parameters
-      assert_equal      app.env_config['action_dispatch.show_exceptions'],   app.config.action_dispatch.show_exceptions
-      assert_equal      app.env_config['action_dispatch.logger'],            Rails.logger
-      assert_equal      app.env_config['action_dispatch.backtrace_cleaner'], Rails.backtrace_cleaner
-      assert_equal      app.env_config['action_dispatch.key_generator'],     Rails.application.key_generator
+      assert_equal      app.env_config["action_dispatch.parameter_filter"],  app.config.filter_parameters
+      assert_equal      app.env_config["action_dispatch.show_exceptions"],   app.config.action_dispatch.show_exceptions
+      assert_equal      app.env_config["action_dispatch.logger"],            Rails.logger
+      assert_equal      app.env_config["action_dispatch.backtrace_cleaner"], Rails.backtrace_cleaner
+      assert_equal      app.env_config["action_dispatch.key_generator"],     Rails.application.key_generator
     end
 
     test "config.colorize_logging default is true" do
@@ -1220,13 +1220,13 @@ module ApplicationTests
     test "config.active_record.dump_schema_after_migration is false on production" do
       build_app
 
-      app 'production'
+      app "production"
 
       assert_not ActiveRecord::Base.dump_schema_after_migration
     end
 
     test "config.active_record.dump_schema_after_migration is true by default on development" do
-      app 'development'
+      app "development"
 
       assert ActiveRecord::Base.dump_schema_after_migration
     end
@@ -1252,12 +1252,12 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
       assert_not Rails.configuration.ran_block
 
-      require 'rake'
-      require 'rake/testtask'
-      require 'rdoc/task'
+      require "rake"
+      require "rake/testtask"
+      require "rdoc/task"
 
       Rails.application.load_tasks
       assert Rails.configuration.ran_block
@@ -1274,7 +1274,7 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
       assert_not Rails.configuration.ran_block
 
       Rails.application.load_generators
@@ -1292,7 +1292,7 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
       assert_not Rails.configuration.ran_block
 
       Rails.application.load_console
@@ -1310,7 +1310,7 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
       assert_not Rails.configuration.ran_block
 
       Rails.application.load_runner
@@ -1318,7 +1318,7 @@ module ApplicationTests
     end
 
     test "loading the first existing database configuration available" do
-      app_file 'config/environments/development.rb', <<-RUBY
+      app_file "config/environments/development.rb", <<-RUBY
 
       Rails.application.configure do
         config.paths.add 'config/database', with: 'config/nonexistent.yml'
@@ -1326,44 +1326,44 @@ module ApplicationTests
         end
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_kind_of Hash, Rails.application.config.database_configuration
     end
 
-    test 'raises with proper error message if no database configuration found' do
+    test "raises with proper error message if no database configuration found" do
       FileUtils.rm("#{app_path}/config/database.yml")
-      app 'development'
+      app "development"
       err = assert_raises RuntimeError do
         Rails.application.config.database_configuration
       end
-      assert_match 'config/database', err.message
+      assert_match "config/database", err.message
     end
 
-    test 'config.action_mailer.show_previews defaults to true in development' do
-      app 'development'
+    test "config.action_mailer.show_previews defaults to true in development" do
+      app "development"
 
       assert Rails.application.config.action_mailer.show_previews
     end
 
-    test 'config.action_mailer.show_previews defaults to false in production' do
-      app 'production'
+    test "config.action_mailer.show_previews defaults to false in production" do
+      app "production"
 
       assert_equal false, Rails.application.config.action_mailer.show_previews
     end
 
-    test 'config.action_mailer.show_previews can be set in the configuration file' do
+    test "config.action_mailer.show_previews can be set in the configuration file" do
       add_to_config <<-RUBY
         config.action_mailer.show_previews = true
       RUBY
 
-      app 'production'
+      app "production"
 
       assert_equal true, Rails.application.config.action_mailer.show_previews
     end
 
     test "config_for loads custom configuration from yaml files" do
-      app_file 'config/custom.yml', <<-RUBY
+      app_file "config/custom.yml", <<-RUBY
       development:
         key: 'custom key'
       RUBY
@@ -1372,13 +1372,13 @@ module ApplicationTests
         config.my_custom_config = config_for('custom')
       RUBY
 
-      app 'development'
+      app "development"
 
-      assert_equal 'custom key', Rails.application.config.my_custom_config['key']
+      assert_equal "custom key", Rails.application.config.my_custom_config["key"]
     end
 
     test "config_for uses the Pathname object if it is provided" do
-      app_file 'config/custom.yml', <<-RUBY
+      app_file "config/custom.yml", <<-RUBY
       development:
         key: 'custom key'
       RUBY
@@ -1387,9 +1387,9 @@ module ApplicationTests
         config.my_custom_config = config_for(Pathname.new(Rails.root.join("config/custom.yml")))
       RUBY
 
-      app 'development'
+      app "development"
 
-      assert_equal 'custom key', Rails.application.config.my_custom_config['key']
+      assert_equal "custom key", Rails.application.config.my_custom_config["key"]
     end
 
     test "config_for raises an exception if the file does not exist" do
@@ -1398,14 +1398,14 @@ module ApplicationTests
       RUBY
 
       exception = assert_raises(RuntimeError) do
-        app 'development'
+        app "development"
       end
 
       assert_equal "Could not load configuration. No such file - #{app_path}/config/custom.yml", exception.message
     end
 
     test "config_for without the environment configured returns an empty hash" do
-      app_file 'config/custom.yml', <<-RUBY
+      app_file "config/custom.yml", <<-RUBY
       test:
         key: 'custom key'
       RUBY
@@ -1414,26 +1414,26 @@ module ApplicationTests
         config.my_custom_config = config_for('custom')
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal({}, Rails.application.config.my_custom_config)
     end
 
     test "config_for with empty file returns an empty hash" do
-      app_file 'config/custom.yml', <<-RUBY
+      app_file "config/custom.yml", <<-RUBY
       RUBY
 
       add_to_config <<-RUBY
         config.my_custom_config = config_for('custom')
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal({}, Rails.application.config.my_custom_config)
     end
 
     test "config_for containing ERB tags should evaluate" do
-      app_file 'config/custom.yml', <<-RUBY
+      app_file "config/custom.yml", <<-RUBY
       development:
         key: <%= 'custom key' %>
       RUBY
@@ -1442,13 +1442,13 @@ module ApplicationTests
         config.my_custom_config = config_for('custom')
       RUBY
 
-      app 'development'
+      app "development"
 
-      assert_equal 'custom key', Rails.application.config.my_custom_config['key']
+      assert_equal "custom key", Rails.application.config.my_custom_config["key"]
     end
 
     test "config_for with syntax error show a more descriptive exception" do
-      app_file 'config/custom.yml', <<-RUBY
+      app_file "config/custom.yml", <<-RUBY
       development:
         key: foo:
       RUBY
@@ -1458,14 +1458,14 @@ module ApplicationTests
       RUBY
 
       exception = assert_raises(RuntimeError) do
-        app 'development'
+        app "development"
       end
 
-      assert_match 'YAML syntax error occurred while parsing', exception.message
+      assert_match "YAML syntax error occurred while parsing", exception.message
     end
 
     test "config_for allows overriding the environment" do
-      app_file 'config/custom.yml', <<-RUBY
+      app_file "config/custom.yml", <<-RUBY
         test:
           key: 'walrus'
         production:
@@ -1477,11 +1477,11 @@ module ApplicationTests
       RUBY
       require "#{app_path}/config/environment"
 
-      assert_equal 'unicorn', Rails.application.config.my_custom_config['key']
+      assert_equal "unicorn", Rails.application.config.my_custom_config["key"]
     end
 
     test "api_only is false by default" do
-      app 'development'
+      app "development"
       refute Rails.application.config.api_only
     end
 
@@ -1489,7 +1489,7 @@ module ApplicationTests
       add_to_config <<-RUBY
         config.api_only = true
       RUBY
-      app 'development'
+      app "development"
 
       Rails.application.load_generators
       assert Rails.configuration.api_only
@@ -1499,7 +1499,7 @@ module ApplicationTests
       add_to_config <<-RUBY
         config.api_only = true
       RUBY
-      app 'development'
+      app "development"
 
       assert_equal :api, Rails.configuration.debug_exception_response_format
     end
@@ -1509,13 +1509,13 @@ module ApplicationTests
         config.api_only = true
       RUBY
 
-      app_file 'config/environments/development.rb', <<-RUBY
+      app_file "config/environments/development.rb", <<-RUBY
       Rails.application.configure do
         config.debug_exception_response_format = :default
       end
       RUBY
 
-      app 'development'
+      app "development"
 
       assert_equal :default, Rails.configuration.debug_exception_response_format
     end
diff --git a/railties/test/application/console_test.rb b/railties/test/application/console_test.rb
index ba60b54df3..3b8062f74b 100644
--- a/railties/test/application/console_test.rb
+++ b/railties/test/application/console_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 class ConsoleTest < ActiveSupport::TestCase
   include ActiveSupport::Testing::Isolation
@@ -29,7 +29,7 @@ class ConsoleTest < ActiveSupport::TestCase
   end
 
   def test_app_can_access_path_helper_method
-    app_file 'config/routes.rb', <<-RUBY
+    app_file "config/routes.rb", <<-RUBY
       Rails.application.routes.draw do
         get 'foo', to: 'foo#index'
       end
@@ -37,7 +37,7 @@ class ConsoleTest < ActiveSupport::TestCase
 
     load_environment
     console_session = irb_context.app
-    assert_equal '/foo', console_session.foo_path
+    assert_equal "/foo", console_session.foo_path
   end
 
   def test_new_session_should_return_integration_session
@@ -88,8 +88,8 @@ class ConsoleTest < ActiveSupport::TestCase
     helper = irb_context.helper
     assert_not_nil helper
     assert_instance_of ActionView::Base, helper
-    assert_equal 'Once upon a time in a world...',
-      helper.truncate('Once upon a time in a world far far away')
+    assert_equal "Once upon a time in a world...",
+      helper.truncate("Once upon a time in a world far far away")
   end
 end
 
@@ -103,7 +103,7 @@ class FullStackConsoleTest < ActiveSupport::TestCase
     skip "PTY unavailable" unless defined?(PTY) && PTY.respond_to?(:open)
 
     build_app
-    app_file 'app/models/post.rb', <<-CODE
+    app_file "app/models/post.rb", <<-CODE
       class Post < ActiveRecord::Base
       end
     CODE
diff --git a/railties/test/application/generators_test.rb b/railties/test/application/generators_test.rb
index 4e300bce63..0d7ccb2278 100644
--- a/railties/test/application/generators_test.rb
+++ b/railties/test/application/generators_test.rb
@@ -113,7 +113,7 @@ module ApplicationTests
     test "generators with string and hash for options should generate symbol keys" do
       with_bare_config do |c|
         c.generators do |g|
-          g.orm    'data_mapper', migration: false
+          g.orm    "data_mapper", migration: false
         end
 
         expected = {
diff --git a/railties/test/application/initializers/frameworks_test.rb b/railties/test/application/initializers/frameworks_test.rb
index 812bb87009..b2cd339c1a 100644
--- a/railties/test/application/initializers/frameworks_test.rb
+++ b/railties/test/application/initializers/frameworks_test.rb
@@ -128,7 +128,7 @@ module ApplicationTests
         end
       RUBY
 
-      require 'rack/test'
+      require "rack/test"
       extend Rack::Test::Methods
 
       get "/foo/included_helpers"
@@ -160,10 +160,10 @@ module ApplicationTests
         end
       RUBY
 
-      require 'rack/test'
+      require "rack/test"
       extend Rack::Test::Methods
 
-      get 'omg/show'
+      get "omg/show"
       assert_equal '{"omg":"omg"}', last_response.body
     end
 
@@ -175,7 +175,7 @@ module ApplicationTests
     end
 
     test "assignment config.encoding to default_charset" do
-      charset = 'Shift_JIS'
+      charset = "Shift_JIS"
       add_to_config "config.encoding = '#{charset}'"
       require "#{app_path}/config/environment"
       assert_equal charset, ActionDispatch::Response.default_charset
@@ -203,7 +203,7 @@ module ApplicationTests
     test "active_record extensions are applied to ActiveRecord" do
       add_to_config "config.active_record.table_name_prefix = 'tbl_'"
       require "#{app_path}/config/environment"
-      assert_equal 'tbl_', ActiveRecord::Base.table_name_prefix
+      assert_equal "tbl_", ActiveRecord::Base.table_name_prefix
     end
 
     test "database middleware doesn't initialize when activerecord is not in frameworks" do
@@ -237,7 +237,7 @@ module ApplicationTests
       begin
         require "#{app_path}/config/environment"
         orig_database_url = ENV.delete("DATABASE_URL")
-        orig_rails_env, Rails.env = Rails.env, 'development'
+        orig_rails_env, Rails.env = Rails.env, "development"
         ActiveRecord::Base.establish_connection
         assert ActiveRecord::Base.connection
         assert_match(/#{ActiveRecord::Base.configurations[Rails.env]['database']}/, ActiveRecord::Base.connection_config[:database])
@@ -252,7 +252,7 @@ module ApplicationTests
       begin
         require "#{app_path}/config/environment"
         orig_database_url = ENV.delete("DATABASE_URL")
-        orig_rails_env, Rails.env = Rails.env, 'development'
+        orig_rails_env, Rails.env = Rails.env, "development"
         database_url_db_name = "db/database_url_db.sqlite3"
         ENV["DATABASE_URL"] = "sqlite3:#{database_url_db_name}"
         ActiveRecord::Base.establish_connection
diff --git a/railties/test/application/initializers/hooks_test.rb b/railties/test/application/initializers/hooks_test.rb
index 3c0c2ac1c0..0309d02730 100644
--- a/railties/test/application/initializers/hooks_test.rb
+++ b/railties/test/application/initializers/hooks_test.rb
@@ -57,7 +57,7 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
       assert $activerecord_configurations
-      assert $activerecord_configurations['development']
+      assert $activerecord_configurations["development"]
     end
 
     test "after_initialize happens after to_prepare in development" do
diff --git a/railties/test/application/initializers/i18n_test.rb b/railties/test/application/initializers/i18n_test.rb
index fcafbb6d04..2b407e4351 100644
--- a/railties/test/application/initializers/i18n_test.rb
+++ b/railties/test/application/initializers/i18n_test.rb
@@ -76,19 +76,19 @@ en:
   foo: "1"
       YAML
 
-      app_file 'app/models/foo.rb', <<-RUBY
+      app_file "app/models/foo.rb", <<-RUBY
         class Foo < ActiveRecord::Base
           @foo = I18n.t(:foo)
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get '/i18n',   :to => lambda { |env| [200, {}, [Foo.instance_variable_get('@foo')]] }
         end
       RUBY
 
-      require 'rack/test'
+      require "rack/test"
       extend Rack::Test::Methods
       load_app
 
@@ -106,13 +106,13 @@ en:
   foo: "1"
       YAML
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get '/i18n',   :to => lambda { |env| [200, {}, [I18n.t(:foo)]] }
         end
       RUBY
 
-      require 'rack/test'
+      require "rack/test"
       extend Rack::Test::Methods
       load_app
 
@@ -141,13 +141,13 @@ en:
   foo: "1"
       YAML
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get '/i18n',   :to => lambda { |env| [200, {}, [I18n.t(:foo)]] }
         end
       RUBY
 
-      require 'rack/test'
+      require "rack/test"
       extend Rack::Test::Methods
       load_app
 
@@ -177,13 +177,13 @@ en:
   foo: "1"
       YAML
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get '/i18n',   :to => lambda { |env| [200, {}, [I18n.load_path.inspect]] }
         end
       RUBY
 
-      require 'rack/test'
+      require "rack/test"
       extend Rack::Test::Methods
       load_app
 
diff --git a/railties/test/application/initializers/notifications_test.rb b/railties/test/application/initializers/notifications_test.rb
index 1a7914b4eb..b847ac6b36 100644
--- a/railties/test/application/initializers/notifications_test.rb
+++ b/railties/test/application/initializers/notifications_test.rb
@@ -39,17 +39,17 @@ module ApplicationTests
       assert_match(/SHOW tables/, logger.logged(:debug).last)
     end
 
-    test 'rails load_config_initializer event is instrumented' do
-      app_file 'config/initializers/foo.rb', ''
+    test "rails load_config_initializer event is instrumented" do
+      app_file "config/initializers/foo.rb", ""
 
       events = []
       callback = ->(*_) { events << _ }
-      ActiveSupport::Notifications.subscribed(callback, 'load_config_initializer.railties') do
+      ActiveSupport::Notifications.subscribed(callback, "load_config_initializer.railties") do
         app
       end
 
       assert_equal %w[load_config_initializer.railties], events.map(&:first)
-      assert_includes events.first.last[:initializer], 'config/initializers/foo.rb'
+      assert_includes events.first.last[:initializer], "config/initializers/foo.rb"
     end
   end
 end
diff --git a/railties/test/application/integration_test_case_test.rb b/railties/test/application/integration_test_case_test.rb
index 68e2de80c4..1118e5037a 100644
--- a/railties/test/application/integration_test_case_test.rb
+++ b/railties/test/application/integration_test_case_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class IntegrationTestCaseTest < ActiveSupport::TestCase
@@ -13,9 +13,9 @@ module ApplicationTests
     end
 
     test "resets Action Mailer test deliveries" do
-      script('generate mailer BaseMailer welcome')
+      script("generate mailer BaseMailer welcome")
 
-      app_file 'test/integration/mailer_integration_test.rb', <<-RUBY
+      app_file "test/integration/mailer_integration_test.rb", <<-RUBY
         require 'test_helper'
 
         class MailerIntegrationTest < ActionDispatch::IntegrationTest
@@ -55,7 +55,7 @@ module ApplicationTests
     end
 
     test "app method of integration tests returns test_app by default" do
-      app_file 'test/integration/default_app_test.rb', <<-RUBY
+      app_file "test/integration/default_app_test.rb", <<-RUBY
         require 'test_helper'
 
         class DefaultAppIntegrationTest < ActionDispatch::IntegrationTest
diff --git a/railties/test/application/loading_test.rb b/railties/test/application/loading_test.rb
index fe1847d8a5..18f8c89790 100644
--- a/railties/test/application/loading_test.rb
+++ b/railties/test/application/loading_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 class LoadingTest < ActiveSupport::TestCase
   include ActiveSupport::Testing::Isolation
@@ -25,11 +25,11 @@ class LoadingTest < ActiveSupport::TestCase
     require "#{rails_root}/config/environment"
     setup_ar!
 
-    p = Post.create(title: 'omg')
+    p = Post.create(title: "omg")
     assert_equal 1, Post.count
-    assert_equal 'omg', p.title
+    assert_equal "omg", p.title
     p = Post.first
-    assert_equal 'omg', p.title
+    assert_equal "omg", p.title
   end
 
   test "concerns in app are autoloaded" do
@@ -102,14 +102,14 @@ class LoadingTest < ActiveSupport::TestCase
       end
     MODEL
 
-    app_file 'config/routes.rb', <<-RUBY
+    app_file "config/routes.rb", <<-RUBY
       Rails.application.routes.draw do
         get '/load',   to: lambda { |env| [200, {}, Post.all] }
         get '/unload', to: lambda { |env| [200, {}, []] }
       end
     RUBY
 
-    require 'rack/test'
+    require "rack/test"
     extend Rack::Test::Methods
 
     require "#{rails_root}/config/environment"
@@ -132,7 +132,7 @@ class LoadingTest < ActiveSupport::TestCase
       config.cache_classes = false
     RUBY
 
-    app_file 'config/routes.rb', <<-RUBY
+    app_file "config/routes.rb", <<-RUBY
       Rails.application.routes.draw do
         get '/c', to: lambda { |env| [200, {"Content-Type" => "text/plain"}, [User.counter.to_s]] }
       end
@@ -144,7 +144,7 @@ class LoadingTest < ActiveSupport::TestCase
       end
     MODEL
 
-    require 'rack/test'
+    require "rack/test"
     extend Rack::Test::Methods
 
     require "#{rails_root}/config/environment"
@@ -173,7 +173,7 @@ class LoadingTest < ActiveSupport::TestCase
       end
     RUBY
 
-    app_file 'config/routes.rb', <<-RUBY
+    app_file "config/routes.rb", <<-RUBY
       Rails.application.routes.draw do
         get '/c', to: lambda { |env| [200, {"Content-Type" => "text/plain"}, [User.counter.to_s]] }
       end
@@ -185,7 +185,7 @@ class LoadingTest < ActiveSupport::TestCase
       end
     MODEL
 
-    require 'rack/test'
+    require "rack/test"
     extend Rack::Test::Methods
 
     require "#{rails_root}/config/environment"
@@ -208,7 +208,7 @@ class LoadingTest < ActiveSupport::TestCase
       config.cache_classes = false
     RUBY
 
-    app_file 'config/routes.rb', <<-RUBY
+    app_file "config/routes.rb", <<-RUBY
       $counter ||= 0
       Rails.application.routes.draw do
         get '/c', to: lambda { |env| User.name; [200, {"Content-Type" => "text/plain"}, [$counter.to_s]] }
@@ -221,7 +221,7 @@ class LoadingTest < ActiveSupport::TestCase
       end
     MODEL
 
-    require 'rack/test'
+    require "rack/test"
     extend Rack::Test::Methods
 
     require "#{rails_root}/config/environment"
@@ -240,7 +240,7 @@ class LoadingTest < ActiveSupport::TestCase
       config.cache_classes = false
     RUBY
 
-    app_file 'config/routes.rb', <<-RUBY
+    app_file "config/routes.rb", <<-RUBY
       $counter ||= 1
       $counter  *= 2
       Rails.application.routes.draw do
@@ -254,7 +254,7 @@ class LoadingTest < ActiveSupport::TestCase
       end
     MODEL
 
-    require 'rack/test'
+    require "rack/test"
     extend Rack::Test::Methods
 
     require "#{rails_root}/config/environment"
@@ -273,7 +273,7 @@ class LoadingTest < ActiveSupport::TestCase
       config.cache_classes = false
     RUBY
 
-    app_file 'config/routes.rb', <<-RUBY
+    app_file "config/routes.rb", <<-RUBY
       Rails.application.routes.draw do
         get '/title', to: lambda { |env| [200, {"Content-Type" => "text/plain"}, [Post.new.title]] }
         get '/body',  to: lambda { |env| [200, {"Content-Type" => "text/plain"}, [Post.new.body]] }
@@ -285,7 +285,7 @@ class LoadingTest < ActiveSupport::TestCase
       end
     MODEL
 
-    require 'rack/test'
+    require "rack/test"
     extend Rack::Test::Methods
 
     app_file "db/migrate/1_create_posts.rb", <<-MIGRATION
@@ -340,11 +340,11 @@ class LoadingTest < ActiveSupport::TestCase
 
     require "#{rails_root}/config/environment"
 
-    require 'rack/test'
+    require "rack/test"
     extend Rack::Test::Methods
 
-    get '/omg/show'
-    assert_equal 'OK', last_response.body
+    get "/omg/show"
+    assert_equal "OK", last_response.body
   end
 
   def test_initialize_can_be_called_at_any_time
diff --git a/railties/test/application/mailer_previews_test.rb b/railties/test/application/mailer_previews_test.rb
index 3ea74423cf..18e3a7bf0e 100644
--- a/railties/test/application/mailer_previews_test.rb
+++ b/railties/test/application/mailer_previews_test.rb
@@ -1,6 +1,6 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
-require 'base64'
+require "isolation/abstract_unit"
+require "rack/test"
+require "base64"
 
 module ApplicationTests
   class MailerPreviewsTest < ActiveSupport::TestCase
@@ -53,7 +53,7 @@ module ApplicationTests
     end
 
     test "mailer previews are loaded from the default preview_path" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -63,11 +63,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -75,7 +75,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers"
       assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
@@ -85,7 +85,7 @@ module ApplicationTests
     test "mailer previews are loaded from a custom preview_path" do
       add_to_config "config.action_mailer.preview_path = '#{app_path}/lib/mailer_previews'"
 
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -95,11 +95,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      app_file 'lib/mailer_previews/notifier_preview.rb', <<-RUBY
+      app_file "lib/mailer_previews/notifier_preview.rb", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -107,7 +107,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers"
       assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
@@ -115,12 +115,12 @@ module ApplicationTests
     end
 
     test "mailer previews are reloaded across requests" do
-      app('development')
+      app("development")
 
       get "/rails/mailers"
       assert_no_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
 
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -130,11 +130,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -145,7 +145,7 @@ module ApplicationTests
       get "/rails/mailers"
       assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
 
-      remove_file 'test/mailers/previews/notifier_preview.rb'
+      remove_file "test/mailers/previews/notifier_preview.rb"
       sleep(1)
 
       get "/rails/mailers"
@@ -153,7 +153,7 @@ module ApplicationTests
     end
 
     test "mailer preview actions are added and removed" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -163,11 +163,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -175,14 +175,14 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers"
       assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
       assert_match '<li><a href="/rails/mailers/notifier/foo">foo</a></li>', last_response.body
       assert_no_match '<li><a href="/rails/mailers/notifier/bar">bar</a></li>', last_response.body
 
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -196,15 +196,15 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      text_template 'notifier/bar', <<-RUBY
+      text_template "notifier/bar", <<-RUBY
         Goodbye, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -223,7 +223,7 @@ module ApplicationTests
       assert_match '<li><a href="/rails/mailers/notifier/foo">foo</a></li>', last_response.body
       assert_match '<li><a href="/rails/mailers/notifier/bar">bar</a></li>', last_response.body
 
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -233,9 +233,9 @@ module ApplicationTests
         end
       RUBY
 
-      remove_file 'app/views/notifier/bar.text.erb'
+      remove_file "app/views/notifier/bar.text.erb"
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -254,12 +254,12 @@ module ApplicationTests
     test "mailer previews are reloaded from a custom preview_path" do
       add_to_config "config.action_mailer.preview_path = '#{app_path}/lib/mailer_previews'"
 
-      app('development')
+      app("development")
 
       get "/rails/mailers"
       assert_no_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
 
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -269,11 +269,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      app_file 'lib/mailer_previews/notifier_preview.rb', <<-RUBY
+      app_file "lib/mailer_previews/notifier_preview.rb", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -284,7 +284,7 @@ module ApplicationTests
       get "/rails/mailers"
       assert_match '<h3><a href="/rails/mailers/notifier">Notifier</a></h3>', last_response.body
 
-      remove_file 'lib/mailer_previews/notifier_preview.rb'
+      remove_file "lib/mailer_previews/notifier_preview.rb"
       sleep(1)
 
       get "/rails/mailers"
@@ -292,14 +292,14 @@ module ApplicationTests
     end
 
     test "mailer preview not found" do
-      app('development')
+      app("development")
       get "/rails/mailers/notifier"
       assert last_response.not_found?
       assert_match "Mailer preview &#39;notifier&#39; not found", last_response.body
     end
 
     test "mailer preview email not found" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -309,11 +309,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -321,7 +321,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/bar"
       assert last_response.not_found?
@@ -329,7 +329,7 @@ module ApplicationTests
     end
 
     test "mailer preview NullMail" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -339,7 +339,7 @@ module ApplicationTests
         end
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -347,7 +347,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/foo"
       assert_match "You are trying to preview an email that does not have any content.", last_response.body
@@ -355,7 +355,7 @@ module ApplicationTests
     end
 
     test "mailer preview email part not found" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -365,11 +365,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -377,7 +377,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/foo?part=text%2Fhtml"
       assert last_response.not_found?
@@ -385,7 +385,7 @@ module ApplicationTests
     end
 
     test "message header uses full display names" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "Ruby on Rails <core@rubyonrails.org>"
 
@@ -396,11 +396,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -408,7 +408,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/foo"
       assert_equal 200, last_response.status
@@ -418,7 +418,7 @@ module ApplicationTests
     end
 
     test "part menu selects correct option" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -428,15 +428,15 @@ module ApplicationTests
         end
       RUBY
 
-      html_template 'notifier/foo', <<-RUBY
+      html_template "notifier/foo", <<-RUBY
         <p>Hello, World!</p>
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -444,7 +444,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/foo.html"
       assert_equal 200, last_response.status
@@ -456,7 +456,7 @@ module ApplicationTests
     end
 
     test "mailer previews create correct links when loaded on a subdirectory" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -466,11 +466,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -478,9 +478,9 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
-      get "/rails/mailers", {}, 'SCRIPT_NAME' => '/my_app'
+      get "/rails/mailers", {}, "SCRIPT_NAME" => "/my_app"
       assert_match '<h3><a href="/my_app/rails/mailers/notifier">Notifier</a></h3>', last_response.body
       assert_match '<li><a href="/my_app/rails/mailers/notifier/foo">foo</a></li>', last_response.body
     end
@@ -488,7 +488,7 @@ module ApplicationTests
     test "plain text mailer preview with attachment" do
       image_file "pixel.png", "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEWzIioca/JlAAAACklEQVQI12NgAAAAAgAB4iG8MwAAAABJRU5ErkJgggo="
 
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -499,11 +499,11 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -511,7 +511,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/foo"
       assert_equal 200, last_response.status
@@ -525,7 +525,7 @@ module ApplicationTests
     test "multipart mailer preview with attachment" do
       image_file "pixel.png", "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEWzIioca/JlAAAACklEQVQI12NgAAAAAgAB4iG8MwAAAABJRU5ErkJgggo="
 
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -536,15 +536,15 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      html_template 'notifier/foo', <<-RUBY
+      html_template "notifier/foo", <<-RUBY
         <p>Hello, World!</p>
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -552,7 +552,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/foo"
       assert_equal 200, last_response.status
@@ -570,7 +570,7 @@ module ApplicationTests
     test "multipart mailer preview with inline attachment" do
       image_file "pixel.png", "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEWzIioca/JlAAAACklEQVQI12NgAAAAAgAB4iG8MwAAAABJRU5ErkJgggo="
 
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -581,16 +581,16 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      html_template 'notifier/foo', <<-RUBY
+      html_template "notifier/foo", <<-RUBY
         <p>Hello, World!</p>
         <%= image_tag attachments['pixel.png'].url %>
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -598,7 +598,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/foo"
       assert_equal 200, last_response.status
@@ -615,7 +615,7 @@ module ApplicationTests
     end
 
     test "multipart mailer preview with attached email" do
-      mailer 'notifier', <<-RUBY
+      mailer "notifier", <<-RUBY
         class Notifier < ActionMailer::Base
           default from: "from@example.com"
 
@@ -640,15 +640,15 @@ module ApplicationTests
         end
       RUBY
 
-      text_template 'notifier/foo', <<-RUBY
+      text_template "notifier/foo", <<-RUBY
         Hello, World!
       RUBY
 
-      html_template 'notifier/foo', <<-RUBY
+      html_template "notifier/foo", <<-RUBY
         <p>Hello, World!</p>
       RUBY
 
-      mailer_preview 'notifier', <<-RUBY
+      mailer_preview "notifier", <<-RUBY
         class NotifierPreview < ActionMailer::Preview
           def foo
             Notifier.foo
@@ -656,7 +656,7 @@ module ApplicationTests
         end
       RUBY
 
-      app('development')
+      app("development")
 
       get "/rails/mailers/notifier/foo"
       assert_equal 200, last_response.status
@@ -694,7 +694,7 @@ module ApplicationTests
       end
 
       def image_file(name, contents)
-        app_file("public/images/#{name}", Base64.strict_decode64(contents), 'wb')
+        app_file("public/images/#{name}", Base64.strict_decode64(contents), "wb")
       end
   end
 end
diff --git a/railties/test/application/middleware/cache_test.rb b/railties/test/application/middleware/cache_test.rb
index 9802de4a60..be44aa774f 100644
--- a/railties/test/application/middleware/cache_test.rb
+++ b/railties/test/application/middleware/cache_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class CacheTest < ActiveSupport::TestCase
@@ -6,7 +6,7 @@ module ApplicationTests
 
     def setup
       build_app
-      require 'rack/test'
+      require "rack/test"
       extend Rack::Test::Methods
     end
 
@@ -43,7 +43,7 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':controller(/:action)'
         end
@@ -65,12 +65,12 @@ module ApplicationTests
       app("development")
 
       get "/expires/expires_header"
-      assert_nil last_response.headers['X-Rack-Cache']
+      assert_nil last_response.headers["X-Rack-Cache"]
 
       body = last_response.body
 
       get "/expires/expires_header"
-      assert_nil last_response.headers['X-Rack-Cache']
+      assert_nil last_response.headers["X-Rack-Cache"]
       assert_not_equal body, last_response.body
     end
 
diff --git a/railties/test/application/middleware/cookies_test.rb b/railties/test/application/middleware/cookies_test.rb
index 7a1a0083b1..1e4b5d086c 100644
--- a/railties/test/application/middleware/cookies_test.rb
+++ b/railties/test/application/middleware/cookies_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class CookiesTest < ActiveSupport::TestCase
@@ -18,27 +18,27 @@ module ApplicationTests
       FileUtils.rm_rf(new_app) if File.directory?(new_app)
     end
 
-    test 'always_write_cookie is true by default in development' do
-      require 'rails'
-      Rails.env = 'development'
+    test "always_write_cookie is true by default in development" do
+      require "rails"
+      Rails.env = "development"
       require "#{app_path}/config/environment"
       assert_equal true, ActionDispatch::Cookies::CookieJar.always_write_cookie
     end
 
-    test 'always_write_cookie is false by default in production' do
-      require 'rails'
-      Rails.env = 'production'
+    test "always_write_cookie is false by default in production" do
+      require "rails"
+      Rails.env = "production"
       require "#{app_path}/config/environment"
       assert_equal false, ActionDispatch::Cookies::CookieJar.always_write_cookie
     end
 
-    test 'always_write_cookie can be overridden' do
+    test "always_write_cookie can be overridden" do
       add_to_config <<-RUBY
         config.action_dispatch.always_write_cookie = false
       RUBY
 
-      require 'rails'
-      Rails.env = 'development'
+      require "rails"
+      Rails.env = "development"
       require "#{app_path}/config/environment"
       assert_equal false, ActionDispatch::Cookies::CookieJar.always_write_cookie
     end
diff --git a/railties/test/application/middleware/exceptions_test.rb b/railties/test/application/middleware/exceptions_test.rb
index 44c0215341..fcc22cc813 100644
--- a/railties/test/application/middleware/exceptions_test.rb
+++ b/railties/test/application/middleware/exceptions_test.rb
@@ -1,5 +1,5 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
+require "isolation/abstract_unit"
+require "rack/test"
 
 module ApplicationTests
   class MiddlewareExceptionsTest < ActiveSupport::TestCase
@@ -69,7 +69,7 @@ module ApplicationTests
 
       app.config.action_dispatch.show_exceptions = true
 
-      get '/foo'
+      get "/foo"
       assert_equal 500, last_response.status
     end
 
@@ -77,7 +77,7 @@ module ApplicationTests
       app.config.action_dispatch.show_exceptions = false
 
       assert_raise(ActionController::RoutingError) do
-        get '/foo'
+        get "/foo"
       end
     end
 
@@ -85,7 +85,7 @@ module ApplicationTests
       app.config.action_dispatch.show_exceptions = true
 
       assert_nothing_raised do
-        get '/foo'
+        get "/foo"
         assert_match "The page you were looking for doesn't exist.", last_response.body
       end
     end
@@ -95,7 +95,7 @@ module ApplicationTests
       app.config.consider_all_requests_local = true
 
       assert_nothing_raised do
-        get '/foo'
+        get "/foo"
         assert_match "No route matches", last_response.body
       end
     end
@@ -111,12 +111,12 @@ module ApplicationTests
       app.config.action_dispatch.show_exceptions = true
       app.config.consider_all_requests_local = true
 
-      app_file 'app/views/foo/index.html.erb', <<-ERB
+      app_file "app/views/foo/index.html.erb", <<-ERB
         <% raise 'boooom' %>
         ✓測試テスト시험
       ERB
 
-      get '/foo', :utf8 => '✓'
+      get "/foo", :utf8 => "✓"
       assert_match(/boooom/, last_response.body)
       assert_match(/測試テスト시험/, last_response.body)
     end
diff --git a/railties/test/application/middleware/remote_ip_test.rb b/railties/test/application/middleware/remote_ip_test.rb
index 37bd8a25c1..c34d9d6ee7 100644
--- a/railties/test/application/middleware/remote_ip_test.rb
+++ b/railties/test/application/middleware/remote_ip_test.rb
@@ -1,6 +1,6 @@
-require 'ipaddr'
-require 'isolation/abstract_unit'
-require 'active_support/key_generator'
+require "ipaddr"
+require "isolation/abstract_unit"
+require "active_support/key_generator"
 
 module ApplicationTests
   class RemoteIpTest < ActiveSupport::TestCase
@@ -9,8 +9,8 @@ module ApplicationTests
     def remote_ip(env = {})
       remote_ip = nil
       env = Rack::MockRequest.env_for("/").merge(env).merge!(
-        'action_dispatch.show_exceptions' => false,
-        'action_dispatch.key_generator'   => ActiveSupport::LegacyKeyGenerator.new('b3c631c314c0bbca50c1b2843150fe33')
+        "action_dispatch.show_exceptions" => false,
+        "action_dispatch.key_generator"   => ActiveSupport::LegacyKeyGenerator.new("b3c631c314c0bbca50c1b2843150fe33")
       )
 
       endpoint = Proc.new do |e|
@@ -69,7 +69,7 @@ module ApplicationTests
 
     test "the user can set trusted proxies with an IPAddr argument" do
       make_basic_app do |app|
-        app.config.action_dispatch.trusted_proxies = IPAddr.new('4.2.42.0/24')
+        app.config.action_dispatch.trusted_proxies = IPAddr.new("4.2.42.0/24")
       end
 
       assert_equal "1.1.1.1", remote_ip("REMOTE_ADDR" => "1.1.1.1", "HTTP_X_FORWARDED_FOR" => "10.0.0.0,4.2.42.42")
diff --git a/railties/test/application/middleware/sendfile_test.rb b/railties/test/application/middleware/sendfile_test.rb
index 18e23ca17b..4938402fdc 100644
--- a/railties/test/application/middleware/sendfile_test.rb
+++ b/railties/test/application/middleware/sendfile_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class SendfileTest < ActiveSupport::TestCase
@@ -48,7 +48,7 @@ module ApplicationTests
 
     test "config.action_dispatch.x_sendfile_header is sent to Rack::Sendfile" do
       make_basic_app do |app|
-        app.config.action_dispatch.x_sendfile_header = 'X-Lighttpd-Send-File'
+        app.config.action_dispatch.x_sendfile_header = "X-Lighttpd-Send-File"
       end
 
       simple_controller
@@ -59,7 +59,7 @@ module ApplicationTests
 
     test "files handled by ActionDispatch::Static are handled by Rack::Sendfile" do
       make_basic_app do |app|
-        app.config.action_dispatch.x_sendfile_header = 'X-Sendfile'
+        app.config.action_dispatch.x_sendfile_header = "X-Sendfile"
         app.config.public_file_server.enabled = true
         app.paths["public"] = File.join(rails_root, "public")
       end
diff --git a/railties/test/application/middleware/session_test.rb b/railties/test/application/middleware/session_test.rb
index 64cae27ea2..2873425703 100644
--- a/railties/test/application/middleware/session_test.rb
+++ b/railties/test/application/middleware/session_test.rb
@@ -1,5 +1,5 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
+require "isolation/abstract_unit"
+require "rack/test"
 
 module ApplicationTests
   class MiddlewareSessionTest < ActiveSupport::TestCase
@@ -53,7 +53,7 @@ module ApplicationTests
     end
 
     test "session is empty and isn't saved on unverified request when using :null_session protect method" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get  ':controller(/:action)'
           post ':controller(/:action)'
@@ -81,20 +81,20 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/foo/write_session'
-      get '/foo/read_session'
-      assert_equal '1', last_response.body
+      get "/foo/write_session"
+      get "/foo/read_session"
+      assert_equal "1", last_response.body
 
-      post '/foo/read_session'               # Read session using POST request without CSRF token
-      assert_equal 'nil', last_response.body # Stored value shouldn't be accessible
+      post "/foo/read_session"               # Read session using POST request without CSRF token
+      assert_equal "nil", last_response.body # Stored value shouldn't be accessible
 
-      post '/foo/write_session' # Write session using POST request without CSRF token
-      get '/foo/read_session'   # Session shouldn't be changed
-      assert_equal '1', last_response.body
+      post "/foo/write_session" # Write session using POST request without CSRF token
+      get "/foo/read_session"   # Session shouldn't be changed
+      assert_equal "1", last_response.body
     end
 
     test "cookie jar is empty and isn't saved on unverified request when using :null_session protect method" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get  ':controller(/:action)'
           post ':controller(/:action)'
@@ -122,20 +122,20 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/foo/write_cookie'
-      get '/foo/read_cookie'
+      get "/foo/write_cookie"
+      get "/foo/read_cookie"
       assert_equal '"1"', last_response.body
 
-      post '/foo/read_cookie'                # Read cookie using POST request without CSRF token
-      assert_equal 'nil', last_response.body # Stored value shouldn't be accessible
+      post "/foo/read_cookie"                # Read cookie using POST request without CSRF token
+      assert_equal "nil", last_response.body # Stored value shouldn't be accessible
 
-      post '/foo/write_cookie' # Write cookie using POST request without CSRF token
-      get '/foo/read_cookie'   # Cookie shouldn't be changed
+      post "/foo/write_cookie" # Write cookie using POST request without CSRF token
+      get "/foo/read_cookie"   # Cookie shouldn't be changed
       assert_equal '"1"', last_response.body
     end
 
     test "session using encrypted cookie store" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':controller(/:action)'
         end
@@ -164,23 +164,23 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/foo/write_session'
-      get '/foo/read_session'
-      assert_equal '1', last_response.body
+      get "/foo/write_session"
+      get "/foo/read_session"
+      assert_equal "1", last_response.body
 
-      get '/foo/read_encrypted_cookie'
-      assert_equal '1', last_response.body
+      get "/foo/read_encrypted_cookie"
+      assert_equal "1", last_response.body
 
-      secret = app.key_generator.generate_key('encrypted cookie')
-      sign_secret = app.key_generator.generate_key('signed encrypted cookie')
+      secret = app.key_generator.generate_key("encrypted cookie")
+      sign_secret = app.key_generator.generate_key("signed encrypted cookie")
       encryptor = ActiveSupport::MessageEncryptor.new(secret, sign_secret)
 
-      get '/foo/read_raw_cookie'
-      assert_equal 1, encryptor.decrypt_and_verify(last_response.body)['foo']
+      get "/foo/read_raw_cookie"
+      assert_equal 1, encryptor.decrypt_and_verify(last_response.body)["foo"]
     end
 
     test "session upgrading signature to encryption cookie store works the same way as encrypted cookie store" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':controller(/:action)'
         end
@@ -213,23 +213,23 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/foo/write_session'
-      get '/foo/read_session'
-      assert_equal '1', last_response.body
+      get "/foo/write_session"
+      get "/foo/read_session"
+      assert_equal "1", last_response.body
 
-      get '/foo/read_encrypted_cookie'
-      assert_equal '1', last_response.body
+      get "/foo/read_encrypted_cookie"
+      assert_equal "1", last_response.body
 
-      secret = app.key_generator.generate_key('encrypted cookie')
-      sign_secret = app.key_generator.generate_key('signed encrypted cookie')
+      secret = app.key_generator.generate_key("encrypted cookie")
+      sign_secret = app.key_generator.generate_key("signed encrypted cookie")
       encryptor = ActiveSupport::MessageEncryptor.new(secret, sign_secret)
 
-      get '/foo/read_raw_cookie'
-      assert_equal 1, encryptor.decrypt_and_verify(last_response.body)['foo']
+      get "/foo/read_raw_cookie"
+      assert_equal 1, encryptor.decrypt_and_verify(last_response.body)["foo"]
     end
 
     test "session upgrading signature to encryption cookie store upgrades session to encrypted mode" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':controller(/:action)'
         end
@@ -268,27 +268,27 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/foo/write_raw_session'
-      get '/foo/read_session'
-      assert_equal '1', last_response.body
+      get "/foo/write_raw_session"
+      get "/foo/read_session"
+      assert_equal "1", last_response.body
 
-      get '/foo/write_session'
-      get '/foo/read_session'
-      assert_equal '2', last_response.body
+      get "/foo/write_session"
+      get "/foo/read_session"
+      assert_equal "2", last_response.body
 
-      get '/foo/read_encrypted_cookie'
-      assert_equal '2', last_response.body
+      get "/foo/read_encrypted_cookie"
+      assert_equal "2", last_response.body
 
-      secret = app.key_generator.generate_key('encrypted cookie')
-      sign_secret = app.key_generator.generate_key('signed encrypted cookie')
+      secret = app.key_generator.generate_key("encrypted cookie")
+      sign_secret = app.key_generator.generate_key("signed encrypted cookie")
       encryptor = ActiveSupport::MessageEncryptor.new(secret, sign_secret)
 
-      get '/foo/read_raw_cookie'
-      assert_equal 2, encryptor.decrypt_and_verify(last_response.body)['foo']
+      get "/foo/read_raw_cookie"
+      assert_equal 2, encryptor.decrypt_and_verify(last_response.body)["foo"]
     end
 
     test "session upgrading legacy signed cookies to new signed cookies" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':controller(/:action)'
         end
@@ -328,25 +328,25 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/foo/write_raw_session'
-      get '/foo/read_session'
-      assert_equal '1', last_response.body
+      get "/foo/write_raw_session"
+      get "/foo/read_session"
+      assert_equal "1", last_response.body
 
-      get '/foo/write_session'
-      get '/foo/read_session'
-      assert_equal '2', last_response.body
+      get "/foo/write_session"
+      get "/foo/read_session"
+      assert_equal "2", last_response.body
 
-      get '/foo/read_signed_cookie'
-      assert_equal '2', last_response.body
+      get "/foo/read_signed_cookie"
+      assert_equal "2", last_response.body
 
       verifier = ActiveSupport::MessageVerifier.new(app.secrets.secret_token)
 
-      get '/foo/read_raw_cookie'
-      assert_equal 2, verifier.verify(last_response.body)['foo']
+      get "/foo/read_raw_cookie"
+      assert_equal 2, verifier.verify(last_response.body)["foo"]
     end
 
-    test 'calling reset_session on request does not trigger an error for API apps' do
-      add_to_config 'config.api_only = true'
+    test "calling reset_session on request does not trigger an error for API apps" do
+      add_to_config "config.api_only = true"
 
       controller :test, <<-RUBY
         class TestController < ApplicationController
@@ -357,7 +357,7 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get '/dump_flash' => "test#dump_flash"
         end
@@ -365,10 +365,10 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/dump_flash'
+      get "/dump_flash"
 
       assert_equal 200, last_response.status
-      assert_equal 'It worked!', last_response.body
+      assert_equal "It worked!", last_response.body
 
       refute Rails.application.middleware.include?(ActionDispatch::Flash)
     end
diff --git a/railties/test/application/middleware/static_test.rb b/railties/test/application/middleware/static_test.rb
index 1246e20d94..8a06e91297 100644
--- a/railties/test/application/middleware/static_test.rb
+++ b/railties/test/application/middleware/static_test.rb
@@ -1,5 +1,5 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
+require "isolation/abstract_unit"
+require "rack/test"
 
 module ApplicationTests
   class MiddlewareStaticTest < ActiveSupport::TestCase
@@ -18,17 +18,17 @@ module ApplicationTests
     # Regression test to #8907
     # See https://github.com/rails/rails/commit/9cc82b77196d21a5c7021f6dca59ab9b2b158a45#commitcomment-2416514
     test "doesn't set Cache-Control header when it is nil" do
-      app_file "public/foo.html", 'static'
+      app_file "public/foo.html", "static"
 
       require "#{app_path}/config/environment"
 
-      get 'foo'
+      get "foo"
 
-      assert_not last_response.headers.has_key?('Cache-Control'), "Cache-Control should not be set"
+      assert_not last_response.headers.has_key?("Cache-Control"), "Cache-Control should not be set"
     end
 
     test "headers for static files are configurable" do
-      app_file "public/about.html", 'static'
+      app_file "public/about.html", "static"
       add_to_config <<-CONFIG
         config.public_file_server.headers = {
           "Access-Control-Allow-Origin" => "http://rubyonrails.org",
@@ -38,10 +38,10 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/about.html'
+      get "/about.html"
 
-      assert_equal 'http://rubyonrails.org', last_response.headers["Access-Control-Allow-Origin"]
-      assert_equal 'public, max-age=60',     last_response.headers["Cache-Control"]
+      assert_equal "http://rubyonrails.org", last_response.headers["Access-Control-Allow-Origin"]
+      assert_equal "public, max-age=60",     last_response.headers["Cache-Control"]
     end
 
     test "public_file_server.index_name defaults to 'index'" do
@@ -49,7 +49,7 @@ module ApplicationTests
       
       require "#{app_path}/config/environment"
 
-      get '/'
+      get "/"
       
       assert_equal "/index.html\n", last_response.body
     end
@@ -60,7 +60,7 @@ module ApplicationTests
 
       require "#{app_path}/config/environment"
 
-      get '/'
+      get "/"
 
       assert_equal "/other-index.html\n", last_response.body
     end
diff --git a/railties/test/application/middleware_test.rb b/railties/test/application/middleware_test.rb
index 23699cae74..3b48ada190 100644
--- a/railties/test/application/middleware_test.rb
+++ b/railties/test/application/middleware_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class MiddlewareTest < ActiveSupport::TestCase
@@ -103,7 +103,7 @@ module ApplicationTests
       add_to_config "config.ssl_options = { host: 'example.com' }"
       boot!
 
-      assert_equal [{host: 'example.com'}], Rails.application.middleware.first.args
+      assert_equal [{host: "example.com"}], Rails.application.middleware.first.args
     end
 
     test "removing Active Record omits its middleware" do
@@ -190,10 +190,10 @@ module ApplicationTests
       assert_equal "Rack::Config", middleware.second
     end
 
-    test 'unshift middleware' do
-      add_to_config 'config.middleware.unshift Rack::Config'
+    test "unshift middleware" do
+      add_to_config "config.middleware.unshift Rack::Config"
       boot!
-      assert_equal 'Rack::Config', middleware.first
+      assert_equal "Rack::Config", middleware.first
     end
 
     test "Rails.cache does not respond to middleware" do
diff --git a/railties/test/application/multiple_applications_test.rb b/railties/test/application/multiple_applications_test.rb
index f9628fe5a8..26b810af73 100644
--- a/railties/test/application/multiple_applications_test.rb
+++ b/railties/test/application/multiple_applications_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class MultipleApplicationsTest < ActiveSupport::TestCase
@@ -7,7 +7,7 @@ module ApplicationTests
     def setup
       build_app(initializers: true)
       require "#{rails_root}/config/environment"
-      Rails.application.config.some_setting = 'something_or_other'
+      Rails.application.config.some_setting = "something_or_other"
     end
 
     def teardown
@@ -87,9 +87,9 @@ module ApplicationTests
       require "#{app_path}/config/environment"
 
       assert_equal 0, run_count, "The count should stay at zero without any calls to the rake tasks"
-      require 'rake'
-      require 'rake/testtask'
-      require 'rdoc/task'
+      require "rake"
+      require "rake/testtask"
+      require "rdoc/task"
       Rails.application.load_tasks
       assert_equal 2, run_count, "Calling a rake task should result in two increments to the count"
     end
diff --git a/railties/test/application/per_request_digest_cache_test.rb b/railties/test/application/per_request_digest_cache_test.rb
index dfe3fc9354..6c003e9bcc 100644
--- a/railties/test/application/per_request_digest_cache_test.rb
+++ b/railties/test/application/per_request_digest_cache_test.rb
@@ -1,9 +1,9 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
-require 'minitest/mock'
+require "isolation/abstract_unit"
+require "rack/test"
+require "minitest/mock"
 
-require 'action_view'
-require 'active_support/testing/method_call_assertions'
+require "action_view"
+require "active_support/testing/method_call_assertions"
 
 class PerRequestDigestCacheTest < ActiveSupport::TestCase
   include ActiveSupport::Testing::Isolation
@@ -12,22 +12,22 @@ class PerRequestDigestCacheTest < ActiveSupport::TestCase
 
   setup do
     build_app
-    add_to_config 'config.consider_all_requests_local = true'
+    add_to_config "config.consider_all_requests_local = true"
 
-    app_file 'app/models/customer.rb', <<-RUBY
+    app_file "app/models/customer.rb", <<-RUBY
       class Customer < Struct.new(:name, :id)
         extend ActiveModel::Naming
         include ActiveModel::Conversion
       end
     RUBY
 
-    app_file 'config/routes.rb', <<-RUBY
+    app_file "config/routes.rb", <<-RUBY
       Rails.application.routes.draw do
         resources :customers, only: :index
       end
     RUBY
 
-    app_file 'app/controllers/customers_controller.rb', <<-RUBY
+    app_file "app/controllers/customers_controller.rb", <<-RUBY
       class CustomersController < ApplicationController
         self.perform_caching = true
 
@@ -37,7 +37,7 @@ class PerRequestDigestCacheTest < ActiveSupport::TestCase
       end
     RUBY
 
-    app_file 'app/views/customers/_customer.html.erb', <<-RUBY
+    app_file "app/views/customers/_customer.html.erb", <<-RUBY
       <% cache customer do %>
         <%= customer.name %>
       <% end %>
@@ -49,17 +49,17 @@ class PerRequestDigestCacheTest < ActiveSupport::TestCase
   teardown :teardown_app
 
   test "digests are reused when rendering the same template twice" do
-    get '/customers'
+    get "/customers"
     assert_equal 200, last_response.status
 
     values = ActionView::LookupContext::DetailsKey.digest_caches.first.values
-    assert_equal [ '8ba099b7749542fe765ff34a6824d548' ], values
+    assert_equal [ "8ba099b7749542fe765ff34a6824d548" ], values
     assert_equal %w(david dingus), last_response.body.split.map(&:strip)
   end
 
   test "template digests are cleared before a request" do
     assert_called(ActionView::LookupContext::DetailsKey, :clear) do
-      get '/customers'
+      get "/customers"
       assert_equal 200, last_response.status
     end
   end
diff --git a/railties/test/application/rack/logger_test.rb b/railties/test/application/rack/logger_test.rb
index 0082ec9cd2..e71bcbc536 100644
--- a/railties/test/application/rack/logger_test.rb
+++ b/railties/test/application/rack/logger_test.rb
@@ -41,13 +41,13 @@ module ApplicationTests
       end
 
       test "logger logs HTTP verb override" do
-        post "/", _method: 'put'
+        post "/", _method: "put"
         wait
         assert_match 'Started PUT "/"', logs
       end
 
       test "logger logs HEAD requests" do
-        post "/", _method: 'head'
+        post "/", _method: "head"
         wait
         assert_match 'Started HEAD "/"', logs
       end
diff --git a/railties/test/application/rackup_test.rb b/railties/test/application/rackup_test.rb
index 4aef9b299c..2943e9ee5d 100644
--- a/railties/test/application/rackup_test.rb
+++ b/railties/test/application/rackup_test.rb
@@ -36,7 +36,7 @@ module ApplicationTests
 
     test "the config object is available on the application object" do
       rackup
-      assert_equal 'UTC', Rails.application.config.time_zone
+      assert_equal "UTC", Rails.application.config.time_zone
     end
   end
 end
diff --git a/railties/test/application/rake/dbs_test.rb b/railties/test/application/rake/dbs_test.rb
index f9bf670c5a..51db634b75 100644
--- a/railties/test/application/rake/dbs_test.rb
+++ b/railties/test/application/rake/dbs_test.rb
@@ -20,7 +20,7 @@ module ApplicationTests
       end
 
       def set_database_url
-        ENV['DATABASE_URL'] = "sqlite3:#{database_url_db_name}"
+        ENV["DATABASE_URL"] = "sqlite3:#{database_url_db_name}"
         # ensure it's using the DATABASE_URL
         FileUtils.rm_rf("#{app_path}/config/database.yml")
       end
@@ -37,12 +37,12 @@ module ApplicationTests
         end
       end
 
-      test 'db:create and db:drop without database url' do
+      test "db:create and db:drop without database url" do
         require "#{app_path}/config/environment"
-        db_create_and_drop ActiveRecord::Base.configurations[Rails.env]['database']
+        db_create_and_drop ActiveRecord::Base.configurations[Rails.env]["database"]
       end
 
-      test 'db:create and db:drop with database url' do
+      test "db:create and db:drop with database url" do
         require "#{app_path}/config/environment"
         set_database_url
         db_create_and_drop database_url_db_name
@@ -57,7 +57,7 @@ module ApplicationTests
         end
       end
 
-      test 'db:create failure because database exists' do
+      test "db:create failure because database exists" do
         with_database_existing do
           output = `bin/rails db:create 2>&1`
           assert_match(/already exists/, output)
@@ -74,7 +74,7 @@ module ApplicationTests
         end
       end
 
-      test 'db:create failure because bad permissions' do
+      test "db:create failure because bad permissions" do
         with_bad_permissions do
           output = `bin/rails db:create 2>&1`
           assert_match(/Couldn't create database/, output)
@@ -82,7 +82,7 @@ module ApplicationTests
         end
       end
 
-      test 'db:drop failure because database does not exist' do
+      test "db:drop failure because database does not exist" do
         Dir.chdir(app_path) do
           output = `bin/rails db:drop:_unsafe --trace 2>&1`
           assert_match(/does not exist/, output)
@@ -90,7 +90,7 @@ module ApplicationTests
         end
       end
 
-      test 'db:drop failure because bad permissions' do
+      test "db:drop failure because bad permissions" do
         with_database_existing do
           with_bad_permissions do
             output = `bin/rails db:drop 2>&1`
@@ -110,12 +110,12 @@ module ApplicationTests
         end
       end
 
-      test 'db:migrate and db:migrate:status without database_url' do
+      test "db:migrate and db:migrate:status without database_url" do
         require "#{app_path}/config/environment"
-        db_migrate_and_status ActiveRecord::Base.configurations[Rails.env]['database']
+        db_migrate_and_status ActiveRecord::Base.configurations[Rails.env]["database"]
       end
 
-      test 'db:migrate and db:migrate:status with database_url' do
+      test "db:migrate and db:migrate:status with database_url" do
         require "#{app_path}/config/environment"
         set_database_url
         db_migrate_and_status database_url_db_name
@@ -130,11 +130,11 @@ module ApplicationTests
         end
       end
 
-      test 'db:schema:dump without database_url' do
+      test "db:schema:dump without database_url" do
         db_schema_dump
       end
 
-      test 'db:schema:dump with database_url' do
+      test "db:schema:dump with database_url" do
         set_database_url
         db_schema_dump
       end
@@ -149,18 +149,18 @@ module ApplicationTests
         end
       end
 
-      test 'db:fixtures:load without database_url' do
+      test "db:fixtures:load without database_url" do
         require "#{app_path}/config/environment"
-        db_fixtures_load ActiveRecord::Base.configurations[Rails.env]['database']
+        db_fixtures_load ActiveRecord::Base.configurations[Rails.env]["database"]
       end
 
-      test 'db:fixtures:load with database_url' do
+      test "db:fixtures:load with database_url" do
         require "#{app_path}/config/environment"
         set_database_url
         db_fixtures_load database_url_db_name
       end
 
-      test 'db:fixtures:load with namespaced fixture' do
+      test "db:fixtures:load with namespaced fixture" do
         require "#{app_path}/config/environment"
         Dir.chdir(app_path) do
           `bin/rails generate model admin::book title:string;
@@ -184,18 +184,18 @@ module ApplicationTests
         end
       end
 
-      test 'db:structure:dump and db:structure:load without database_url' do
+      test "db:structure:dump and db:structure:load without database_url" do
         require "#{app_path}/config/environment"
-        db_structure_dump_and_load ActiveRecord::Base.configurations[Rails.env]['database']
+        db_structure_dump_and_load ActiveRecord::Base.configurations[Rails.env]["database"]
       end
 
-      test 'db:structure:dump and db:structure:load with database_url' do
+      test "db:structure:dump and db:structure:load with database_url" do
         require "#{app_path}/config/environment"
         set_database_url
         db_structure_dump_and_load database_url_db_name
       end
 
-      test 'db:structure:dump does not dump schema information when no migrations are used' do
+      test "db:structure:dump does not dump schema information when no migrations are used" do
         Dir.chdir(app_path) do
           # create table without migrations
           `bin/rails runner 'ActiveRecord::Base.connection.create_table(:posts) {|t| t.string :title }'`
@@ -207,11 +207,11 @@ module ApplicationTests
         end
       end
 
-      test 'db:schema:load and db:structure:load do not purge the existing database' do
+      test "db:schema:load and db:structure:load do not purge the existing database" do
         Dir.chdir(app_path) do
           `bin/rails runner 'ActiveRecord::Base.connection.create_table(:posts) {|t| t.string :title }'`
 
-          app_file 'db/schema.rb', <<-RUBY
+          app_file "db/schema.rb", <<-RUBY
             ActiveRecord::Schema.define(version: 20140423102712) do
               create_table(:comments) {}
             end
@@ -223,7 +223,7 @@ module ApplicationTests
           `bin/rails db:schema:load`
           assert_equal '["posts", "comments", "schema_migrations", "ar_internal_metadata"]', list_tables[]
 
-          app_file 'db/structure.sql', <<-SQL
+          app_file "db/structure.sql", <<-SQL
             CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar(255));
           SQL
 
@@ -234,15 +234,15 @@ module ApplicationTests
 
       test "db:schema:load with inflections" do
         Dir.chdir(app_path) do
-          app_file 'config/initializers/inflection.rb', <<-RUBY
+          app_file "config/initializers/inflection.rb", <<-RUBY
             ActiveSupport::Inflector.inflections do |inflect|
               inflect.irregular 'goose', 'geese'
             end
           RUBY
-          app_file 'config/initializers/primary_key_table_name.rb', <<-RUBY
+          app_file "config/initializers/primary_key_table_name.rb", <<-RUBY
             ActiveRecord::Base.primary_key_prefix_type = :table_name
           RUBY
-          app_file 'db/schema.rb', <<-RUBY
+          app_file "db/schema.rb", <<-RUBY
             ActiveRecord::Schema.define(version: 20140423102712) do
               create_table("goose".pluralize) do |t|
                 t.string :name
@@ -269,24 +269,24 @@ module ApplicationTests
           require "#{app_path}/app/models/book"
           #if structure is not loaded correctly, exception would be raised
           assert_equal 0, Book.count
-          assert_match ActiveRecord::Base.configurations['test']['database'],
+          assert_match ActiveRecord::Base.configurations["test"]["database"],
             ActiveRecord::Base.connection_config[:database]
         end
       end
 
-      test 'db:test:load_structure without database_url' do
+      test "db:test:load_structure without database_url" do
         require "#{app_path}/config/environment"
         db_test_load_structure
       end
 
-      test 'db:setup loads schema and seeds database' do
+      test "db:setup loads schema and seeds database" do
         begin
           @old_rails_env = ENV["RAILS_ENV"]
           @old_rack_env = ENV["RACK_ENV"]
           ENV.delete "RAILS_ENV"
           ENV.delete "RACK_ENV"
 
-          app_file 'db/schema.rb', <<-RUBY
+          app_file "db/schema.rb", <<-RUBY
             ActiveRecord::Schema.define(version: "1") do
               create_table :users do |t|
                 t.string :name
@@ -294,7 +294,7 @@ module ApplicationTests
             end
           RUBY
 
-          app_file 'db/seeds.rb', <<-RUBY
+          app_file "db/seeds.rb", <<-RUBY
             puts ActiveRecord::Base.connection_config[:database]
           RUBY
 
diff --git a/railties/test/application/rake/dev_test.rb b/railties/test/application/rake/dev_test.rb
index 2330ad3535..4f992d9c8d 100644
--- a/railties/test/application/rake/dev_test.rb
+++ b/railties/test/application/rake/dev_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   module RakeTests
@@ -13,24 +13,24 @@ module ApplicationTests
         teardown_app
       end
 
-      test 'dev:cache creates file and outputs message' do
+      test "dev:cache creates file and outputs message" do
         Dir.chdir(app_path) do
           output = `rails dev:cache`
-          assert File.exist?('tmp/caching-dev.txt')
+          assert File.exist?("tmp/caching-dev.txt")
           assert_match(/Development mode is now being cached/, output)
         end
       end
 
-      test 'dev:cache deletes file and outputs message' do
+      test "dev:cache deletes file and outputs message" do
         Dir.chdir(app_path) do
           `rails dev:cache` # Create caching file.
           output = `rails dev:cache` # Delete caching file.
-          assert_not File.exist?('tmp/caching-dev.txt')
+          assert_not File.exist?("tmp/caching-dev.txt")
           assert_match(/Development mode is no longer being cached/, output)
         end
       end
 
-      test 'dev:cache removes server.pid also' do
+      test "dev:cache removes server.pid also" do
         Dir.chdir(app_path) do
           FileUtils.mkdir_p("tmp/pids")
           FileUtils.touch("tmp/pids/server.pid")
diff --git a/railties/test/application/rake/framework_test.rb b/railties/test/application/rake/framework_test.rb
index 04e54b2c70..7ac37b7700 100644
--- a/railties/test/application/rake/framework_test.rb
+++ b/railties/test/application/rake/framework_test.rb
@@ -16,14 +16,14 @@ module ApplicationTests
       end
 
       def load_tasks
-        require 'rake'
-        require 'rdoc/task'
-        require 'rake/testtask'
+        require "rake"
+        require "rdoc/task"
+        require "rake/testtask"
 
         Rails.application.load_tasks
       end
 
-      test 'requiring the rake task should not define method .app_generator on Object' do
+      test "requiring the rake task should not define method .app_generator on Object" do
         require "#{app_path}/config/environment"
 
         load_tasks
@@ -33,7 +33,7 @@ module ApplicationTests
         end
       end
 
-      test 'requiring the rake task should not define method .invoke_from_app_generator on Object' do
+      test "requiring the rake task should not define method .invoke_from_app_generator on Object" do
         require "#{app_path}/config/environment"
 
         load_tasks
diff --git a/railties/test/application/rake/migrations_test.rb b/railties/test/application/rake/migrations_test.rb
index 35f14a9b84..b3e95769fa 100644
--- a/railties/test/application/rake/migrations_test.rb
+++ b/railties/test/application/rake/migrations_test.rb
@@ -12,7 +12,7 @@ module ApplicationTests
         teardown_app
       end
 
-      test 'running migrations with given scope' do
+      test "running migrations with given scope" do
         Dir.chdir(app_path) do
           `bin/rails generate model user username:string password:string`
 
@@ -37,7 +37,7 @@ module ApplicationTests
         end
       end
 
-      test 'model and migration generator with change syntax' do
+      test "model and migration generator with change syntax" do
         Dir.chdir(app_path) do
           `bin/rails generate model user username:string password:string;
            bin/rails generate migration add_email_to_users email:string`
@@ -56,12 +56,12 @@ module ApplicationTests
         end
       end
 
-      test 'migration status when schema migrations table is not present' do
+      test "migration status when schema migrations table is not present" do
         output = Dir.chdir(app_path){ `bin/rails db:migrate:status 2>&1` }
         assert_equal "Schema migrations table does not exist yet.\n", output
       end
 
-      test 'test migration status' do
+      test "test migration status" do
         Dir.chdir(app_path) do
           `bin/rails generate model user username:string password:string;
            bin/rails generate migration add_email_to_users email:string;
@@ -80,8 +80,8 @@ module ApplicationTests
         end
       end
 
-      test 'migration status without timestamps' do
-        add_to_config('config.active_record.timestamped_migrations = false')
+      test "migration status without timestamps" do
+        add_to_config("config.active_record.timestamped_migrations = false")
 
         Dir.chdir(app_path) do
           `bin/rails generate model user username:string password:string;
@@ -101,7 +101,7 @@ module ApplicationTests
         end
       end
 
-      test 'test migration status after rollback and redo' do
+      test "test migration status after rollback and redo" do
         Dir.chdir(app_path) do
           `bin/rails generate model user username:string password:string;
            bin/rails generate migration add_email_to_users email:string;
@@ -126,8 +126,8 @@ module ApplicationTests
         end
       end
 
-      test 'migration status after rollback and redo without timestamps' do
-        add_to_config('config.active_record.timestamped_migrations = false')
+      test "migration status after rollback and redo without timestamps" do
+        add_to_config("config.active_record.timestamped_migrations = false")
 
         Dir.chdir(app_path) do
           `bin/rails generate model user username:string password:string;
@@ -153,7 +153,7 @@ module ApplicationTests
         end
       end
 
-      test 'running migrations with not timestamp head migration files' do
+      test "running migrations with not timestamp head migration files" do
         Dir.chdir(app_path) do
 
           app_file "db/migrate/1_one_migration.rb", <<-MIGRATION
@@ -175,8 +175,8 @@ module ApplicationTests
         end
       end
 
-      test 'schema generation when dump_schema_after_migration is set' do
-        add_to_config('config.active_record.dump_schema_after_migration = false')
+      test "schema generation when dump_schema_after_migration is set" do
+        add_to_config("config.active_record.dump_schema_after_migration = false")
 
         Dir.chdir(app_path) do
           `bin/rails generate model book title:string`
@@ -187,7 +187,7 @@ module ApplicationTests
           assert !File.exist?("db/schema.rb"), "should not dump schema when configured not to"
         end
 
-        add_to_config('config.active_record.dump_schema_after_migration = true')
+        add_to_config("config.active_record.dump_schema_after_migration = true")
 
         Dir.chdir(app_path) do
           `bin/rails generate model reviews book_id:integer`
@@ -198,7 +198,7 @@ module ApplicationTests
         end
       end
 
-      test 'default schema generation after migration' do
+      test "default schema generation after migration" do
         Dir.chdir(app_path) do
           `bin/rails generate model book title:string;
            bin/rails db:migrate`
@@ -208,7 +208,7 @@ module ApplicationTests
         end
       end
 
-      test 'test migration status migrated file is deleted' do
+      test "test migration status migrated file is deleted" do
         Dir.chdir(app_path) do
           `bin/rails generate model user username:string password:string;
            bin/rails generate migration add_email_to_users email:string;
@@ -216,7 +216,7 @@ module ApplicationTests
            rm db/migrate/*email*.rb`
 
           output = `bin/rails db:migrate:status`
-          File.write('test.txt', output)
+          File.write("test.txt", output)
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+\** NO FILE \**/, output)
diff --git a/railties/test/application/rake/notes_test.rb b/railties/test/application/rake/notes_test.rb
index 7d1e3efed2..c0ff3af193 100644
--- a/railties/test/application/rake/notes_test.rb
+++ b/railties/test/application/rake/notes_test.rb
@@ -1,5 +1,5 @@
 require "isolation/abstract_unit"
-require 'rails/source_annotation_extractor'
+require "rails/source_annotation_extractor"
 
 module ApplicationTests
   module RakeTests
@@ -17,15 +17,15 @@ module ApplicationTests
         teardown_app
       end
 
-      test 'notes finds notes for certain file_types' do
+      test "notes finds notes for certain file_types" do
         app_file "app/views/home/index.html.erb", "<% # TODO: note in erb %>"
         app_file "app/assets/javascripts/application.js", "// TODO: note in js"
         app_file "app/assets/stylesheets/application.css", "// TODO: note in css"
         app_file "app/controllers/application_controller.rb", 1000.times.map { "" }.join("\n") << "# TODO: note in ruby"
         app_file "lib/tasks/task.rake", "# TODO: note in rake"
-        app_file 'app/views/home/index.html.builder', '# TODO: note in builder'
-        app_file 'config/locales/en.yml', '# TODO: note in yml'
-        app_file 'config/locales/en.yaml', '# TODO: note in yaml'
+        app_file "app/views/home/index.html.builder", "# TODO: note in builder"
+        app_file "config/locales/en.yml", "# TODO: note in yml"
+        app_file "config/locales/en.yaml", "# TODO: note in yaml"
         app_file "app/views/home/index.ruby", "# TODO: note in ruby"
 
         run_rake_notes do |output, lines|
@@ -43,7 +43,7 @@ module ApplicationTests
         end
       end
 
-      test 'notes finds notes in default directories' do
+      test "notes finds notes in default directories" do
         app_file "app/controllers/some_controller.rb", "# TODO: note in app directory"
         app_file "config/initializers/some_initializer.rb", "# TODO: note in config directory"
         app_file "db/some_seeds.rb", "# TODO: note in db directory"
@@ -65,7 +65,7 @@ module ApplicationTests
         end
       end
 
-      test 'notes finds notes in custom directories' do
+      test "notes finds notes in custom directories" do
         app_file "app/controllers/some_controller.rb", "# TODO: note in app directory"
         app_file "config/initializers/some_initializer.rb", "# TODO: note in config directory"
         app_file "db/some_seeds.rb", "# TODO: note in db directory"
@@ -88,7 +88,7 @@ module ApplicationTests
         end
       end
 
-      test 'custom rake task finds specific notes in specific directories' do
+      test "custom rake task finds specific notes in specific directories" do
         app_file "app/controllers/some_controller.rb", "# TODO: note in app directory"
         app_file "lib/some_file.rb", "# OPTIMIZE: note in lib directory\n" << "# FIXME: note in lib directory"
         app_file "test/some_test.rb", 1000.times.map { "" }.join("\n") << "# TODO: note in test directory"
@@ -113,7 +113,7 @@ module ApplicationTests
         end
       end
 
-      test 'register a new extension' do
+      test "register a new extension" do
         add_to_config "config.assets.precompile = []"
         add_to_config %q{ config.annotations.register_extensions("scss", "sass") { |annotation| /\/\/\s*(#{annotation}):?\s*(.*)$/ } }
         app_file "app/assets/stylesheets/application.css.scss", "// TODO: note in scss"
@@ -126,7 +126,7 @@ module ApplicationTests
         end
       end
 
-      test 'register additional directories' do
+      test "register additional directories" do
         app_file "spec/spec_helper.rb", "# TODO: note in spec"
         app_file "spec/models/user_spec.rb", "# TODO: note in model spec"
         add_to_config %q{ config.annotations.register_directories("spec") }
@@ -140,7 +140,7 @@ module ApplicationTests
 
       private
 
-      def run_rake_notes(command = 'bin/rails notes')
+      def run_rake_notes(command = "bin/rails notes")
         boot_rails
         load_tasks
 
@@ -153,9 +153,9 @@ module ApplicationTests
       end
 
       def load_tasks
-        require 'rake'
-        require 'rdoc/task'
-        require 'rake/testtask'
+        require "rake"
+        require "rdoc/task"
+        require "rake/testtask"
 
         Rails.application.load_tasks
       end
diff --git a/railties/test/application/rake/restart_test.rb b/railties/test/application/rake/restart_test.rb
index 78769a6de5..28da8164a7 100644
--- a/railties/test/application/rake/restart_test.rb
+++ b/railties/test/application/rake/restart_test.rb
@@ -13,7 +13,7 @@ module ApplicationTests
         teardown_app
       end
 
-      test 'rake restart touches tmp/restart.txt' do
+      test "rake restart touches tmp/restart.txt" do
         Dir.chdir(app_path) do
           `rake restart`
           assert File.exist?("tmp/restart.txt")
@@ -26,15 +26,15 @@ module ApplicationTests
         end
       end
 
-      test 'rake restart should work even if tmp folder does not exist' do
+      test "rake restart should work even if tmp folder does not exist" do
         Dir.chdir(app_path) do
-          FileUtils.remove_dir('tmp')
+          FileUtils.remove_dir("tmp")
           `rake restart`
-          assert File.exist?('tmp/restart.txt')
+          assert File.exist?("tmp/restart.txt")
         end
       end
 
-      test 'rake restart removes server.pid also' do
+      test "rake restart removes server.pid also" do
         Dir.chdir(app_path) do
           FileUtils.mkdir_p("tmp/pids")
           FileUtils.touch("tmp/pids/server.pid")
diff --git a/railties/test/application/rake_test.rb b/railties/test/application/rake_test.rb
index 45ea506226..5bb97a593d 100644
--- a/railties/test/application/rake_test.rb
+++ b/railties/test/application/rake_test.rb
@@ -82,7 +82,7 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'app/models/hello.rb', <<-RUBY
+      app_file "app/models/hello.rb", <<-RUBY
         class Hello
           def world
             puts 'Hello world'
@@ -91,7 +91,7 @@ module ApplicationTests
       RUBY
 
       output = Dir.chdir(app_path) { `bin/rails do_nothing` }
-      assert_match 'Hello world', output
+      assert_match "Hello world", output
     end
 
     def test_should_not_eager_load_model_for_rake
@@ -102,17 +102,17 @@ module ApplicationTests
         end
       RUBY
 
-      add_to_env_config 'production', <<-RUBY
+      add_to_env_config "production", <<-RUBY
         config.eager_load = true
       RUBY
 
-      app_file 'app/models/hello.rb', <<-RUBY
+      app_file "app/models/hello.rb", <<-RUBY
         raise 'should not be pre-required for rake even eager_load=true'
       RUBY
 
       Dir.chdir(app_path) do
-        assert system('bin/rails do_nothing RAILS_ENV=production'),
-               'should not be pre-required for rake even eager_load=true'
+        assert system("bin/rails do_nothing RAILS_ENV=production"),
+               "should not be pre-required for rake even eager_load=true"
       end
     end
 
@@ -346,7 +346,7 @@ module ApplicationTests
         # ensure we have a schema_migrations table to dump
         `bin/rails db:migrate db:structure:dump SCHEMA=db/my_structure.sql`
       end
-      assert File.exist?(File.join(app_path, 'db', 'my_structure.sql'))
+      assert File.exist?(File.join(app_path, "db", "my_structure.sql"))
     end
 
     def test_rake_dump_structure_should_be_called_twice_when_migrate_redo
@@ -367,24 +367,24 @@ module ApplicationTests
          bin/rails generate model product name:string;
          bin/rails db:migrate db:schema:cache:dump`
       end
-      assert File.exist?(File.join(app_path, 'db', 'schema_cache.dump'))
+      assert File.exist?(File.join(app_path, "db", "schema_cache.dump"))
     end
 
     def test_rake_clear_schema_cache
       Dir.chdir(app_path) do
         `bin/rails db:schema:cache:dump db:schema:cache:clear`
       end
-      assert !File.exist?(File.join(app_path, 'db', 'schema_cache.dump'))
+      assert !File.exist?(File.join(app_path, "db", "schema_cache.dump"))
     end
 
     def test_copy_templates
       Dir.chdir(app_path) do
         `bin/rails app:templates:copy`
         %w(controller mailer scaffold).each do |dir|
-          assert File.exist?(File.join(app_path, 'lib', 'templates', 'erb', dir))
+          assert File.exist?(File.join(app_path, "lib", "templates", "erb", dir))
         end
         %w(controller helper scaffold_controller assets).each do |dir|
-          assert File.exist?(File.join(app_path, 'lib', 'templates', 'rails', dir))
+          assert File.exist?(File.join(app_path, "lib", "templates", "rails", dir))
         end
       end
     end
diff --git a/railties/test/application/rendering_test.rb b/railties/test/application/rendering_test.rb
index 9514547608..ccafc5b6f1 100644
--- a/railties/test/application/rendering_test.rb
+++ b/railties/test/application/rendering_test.rb
@@ -1,5 +1,5 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
+require "isolation/abstract_unit"
+require "rack/test"
 
 module ApplicationTests
   class RoutingTest < ActiveSupport::TestCase
@@ -15,13 +15,13 @@ module ApplicationTests
     end
 
     test "Unknown format falls back to HTML template" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get 'pages/:id', to: 'pages#show'
         end
       RUBY
 
-      app_file 'app/controllers/pages_controller.rb', <<-RUBY
+      app_file "app/controllers/pages_controller.rb", <<-RUBY
         class PagesController < ApplicationController
           layout false
 
@@ -30,14 +30,14 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'app/views/pages/show.html.erb', <<-RUBY
+      app_file "app/views/pages/show.html.erb", <<-RUBY
         <%= params[:id] %>
       RUBY
 
-      get '/pages/foo'
+      get "/pages/foo"
       assert_equal 200, last_response.status
 
-      get '/pages/foo.bar'
+      get "/pages/foo.bar"
       assert_equal 200, last_response.status
     end
   end
diff --git a/railties/test/application/routing_test.rb b/railties/test/application/routing_test.rb
index 8e7df71880..27058cbc5c 100644
--- a/railties/test/application/routing_test.rb
+++ b/railties/test/application/routing_test.rb
@@ -1,5 +1,5 @@
-require 'isolation/abstract_unit'
-require 'rack/test'
+require "isolation/abstract_unit"
+require "rack/test"
 
 module ApplicationTests
   class RoutingTest < ActiveSupport::TestCase
@@ -60,7 +60,7 @@ module ApplicationTests
     test "root takes precedence over internal welcome controller" do
       app("development")
 
-      assert_welcome get('/')
+      assert_welcome get("/")
 
       controller :foo, <<-RUBY
         class FooController < ApplicationController
@@ -70,14 +70,14 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           root to: "foo#index"
         end
       RUBY
 
-      get '/'
-      assert_equal 'foo', last_response.body
+      get "/"
+      assert_equal "foo", last_response.body
     end
 
     test "rails/welcome in production" do
@@ -107,8 +107,8 @@ module ApplicationTests
     test "simple controller" do
       simple_controller
 
-      get '/foo'
-      assert_equal 'foo', last_response.body
+      get "/foo"
+      assert_equal "foo", last_response.body
     end
 
     test "simple controller with helper" do
@@ -120,7 +120,7 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'app/helpers/bar_helper.rb', <<-RUBY
+      app_file "app/helpers/bar_helper.rb", <<-RUBY
         module BarHelper
           def foo_or_bar?
             "bar"
@@ -128,18 +128,18 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':controller(/:action)'
         end
       RUBY
 
-      get '/foo'
-      assert_equal 'bar', last_response.body
+      get "/foo"
+      assert_equal "bar", last_response.body
     end
 
     test "mount rack app" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           mount lambda { |env| [200, {}, [env["PATH_INFO"]]] }, at: "/blog"
           # The line below is required because mount sometimes
@@ -148,8 +148,8 @@ module ApplicationTests
         end
       RUBY
 
-      get '/blog/archives'
-      assert_equal '/archives', last_response.body
+      get "/blog/archives"
+      assert_equal "/archives", last_response.body
     end
 
     test "mount named rack app" do
@@ -161,15 +161,15 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           mount lambda { |env| [200, {}, [env["PATH_INFO"]]] }, at: "/blog", as: "my_blog"
           get '/foo' => 'foo#index'
         end
       RUBY
 
-      get '/foo'
-      assert_equal '/blog', last_response.body
+      get "/foo"
+      assert_equal "/blog", last_response.body
     end
 
     test "multiple controllers" do
@@ -189,21 +189,21 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':controller(/:action)'
         end
       RUBY
 
-      get '/foo'
-      assert_equal 'foo', last_response.body
+      get "/foo"
+      assert_equal "foo", last_response.body
 
-      get '/bar'
-      assert_equal 'bar', last_response.body
+      get "/bar"
+      assert_equal "bar", last_response.body
     end
 
     test "nested controller" do
-      controller 'foo', <<-RUBY
+      controller "foo", <<-RUBY
         class FooController < ApplicationController
           def index
             render text: "foo"
@@ -211,7 +211,7 @@ module ApplicationTests
         end
       RUBY
 
-      controller 'admin/foo', <<-RUBY
+      controller "admin/foo", <<-RUBY
         module Admin
           class FooController < ApplicationController
             def index
@@ -221,22 +221,22 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get 'admin/foo', to: 'admin/foo#index'
           get 'foo', to: 'foo#index'
         end
       RUBY
 
-      get '/foo'
-      assert_equal 'foo', last_response.body
+      get "/foo"
+      assert_equal "foo", last_response.body
 
-      get '/admin/foo'
-      assert_equal 'admin::foo', last_response.body
+      get "/admin/foo"
+      assert_equal "admin::foo", last_response.body
     end
 
     test "routes appending blocks" do
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':controller/:action'
         end
@@ -248,19 +248,19 @@ module ApplicationTests
         end
       R
 
-      app 'development'
+      app "development"
 
-      get '/win'
-      assert_equal 'WIN', last_response.body
+      get "/win"
+      assert_equal "WIN", last_response.body
 
-      app_file 'config/routes.rb', <<-R
+      app_file "config/routes.rb", <<-R
         Rails.application.routes.draw do
           get 'lol' => 'hello#index'
         end
       R
 
-      get '/win'
-      assert_equal 'WIN', last_response.body
+      get "/win"
+      assert_equal "WIN", last_response.body
     end
 
     {"development" => "baz", "production" => "bar"}.each do |mode, expected|
@@ -277,7 +277,7 @@ module ApplicationTests
           end
         RUBY
 
-        app_file 'config/routes.rb', <<-RUBY
+        app_file "config/routes.rb", <<-RUBY
           Rails.application.routes.draw do
             get 'foo', to: 'foo#bar'
           end
@@ -285,10 +285,10 @@ module ApplicationTests
 
         app(mode)
 
-        get '/foo'
-        assert_equal 'bar', last_response.body
+        get "/foo"
+        assert_equal "bar", last_response.body
 
-        app_file 'config/routes.rb', <<-RUBY
+        app_file "config/routes.rb", <<-RUBY
           Rails.application.routes.draw do
             get 'foo', to: 'foo#baz'
           end
@@ -296,12 +296,12 @@ module ApplicationTests
 
         sleep 0.1
 
-        get '/foo'
+        get "/foo"
         assert_equal expected, last_response.body
       end
     end
 
-    test 'routes are loaded just after initialization' do
+    test "routes are loaded just after initialization" do
       require "#{app_path}/config/application"
 
       # Create the rack app just inside after initialize callback
@@ -309,17 +309,17 @@ module ApplicationTests
         ::InitializeRackApp = lambda { |env| [200, {}, ["InitializeRackApp"]] }
       end
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get 'foo', to: ::InitializeRackApp
         end
       RUBY
 
-      get '/foo'
+      get "/foo"
       assert_equal "InitializeRackApp", last_response.body
     end
 
-    test 'reload_routes! is part of Rails.application API' do
+    test "reload_routes! is part of Rails.application API" do
       app("development")
       assert_nothing_raised do
         Rails.application.reload_routes!
@@ -327,7 +327,7 @@ module ApplicationTests
     end
 
     def test_root_path
-      app('development')
+      app("development")
 
       controller :foo, <<-RUBY
         class FooController < ApplicationController
@@ -337,21 +337,21 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get 'foo', :to => 'foo#index'
           root :to => 'foo#index'
         end
       RUBY
 
-      remove_file 'public/index.html'
+      remove_file "public/index.html"
 
-      get '/'
-      assert_equal 'foo', last_response.body
+      get "/"
+      assert_equal "foo", last_response.body
     end
 
-    test 'routes are added and removed when reloading' do
-      app('development')
+    test "routes are added and removed when reloading" do
+      app("development")
 
       controller :foo, <<-RUBY
         class FooController < ApplicationController
@@ -369,23 +369,23 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get 'foo', to: 'foo#index'
         end
       RUBY
 
-      get '/foo'
-      assert_equal 'foo', last_response.body
-      assert_equal '/foo', Rails.application.routes.url_helpers.foo_path
+      get "/foo"
+      assert_equal "foo", last_response.body
+      assert_equal "/foo", Rails.application.routes.url_helpers.foo_path
 
-      get '/bar'
+      get "/bar"
       assert_equal 404, last_response.status
       assert_raises NoMethodError do
-        assert_equal '/bar', Rails.application.routes.url_helpers.bar_path
+        assert_equal "/bar", Rails.application.routes.url_helpers.bar_path
       end
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get 'foo', to: 'foo#index'
           get 'bar', to: 'bar#index'
@@ -394,15 +394,15 @@ module ApplicationTests
 
       Rails.application.reload_routes!
 
-      get '/foo'
-      assert_equal 'foo', last_response.body
-      assert_equal '/foo', Rails.application.routes.url_helpers.foo_path
+      get "/foo"
+      assert_equal "foo", last_response.body
+      assert_equal "/foo", Rails.application.routes.url_helpers.foo_path
 
-      get '/bar'
-      assert_equal 'bar', last_response.body
-      assert_equal '/bar', Rails.application.routes.url_helpers.bar_path
+      get "/bar"
+      assert_equal "bar", last_response.body
+      assert_equal "/bar", Rails.application.routes.url_helpers.bar_path
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get 'foo', to: 'foo#index'
         end
@@ -410,19 +410,19 @@ module ApplicationTests
 
       Rails.application.reload_routes!
 
-      get '/foo'
-      assert_equal 'foo', last_response.body
-      assert_equal '/foo', Rails.application.routes.url_helpers.foo_path
+      get "/foo"
+      assert_equal "foo", last_response.body
+      assert_equal "/foo", Rails.application.routes.url_helpers.foo_path
 
-      get '/bar'
+      get "/bar"
       assert_equal 404, last_response.status
       assert_raises NoMethodError do
-        assert_equal '/bar', Rails.application.routes.url_helpers.bar_path
+        assert_equal "/bar", Rails.application.routes.url_helpers.bar_path
       end
     end
 
-    test 'named routes are cleared when reloading' do
-      app('development')
+    test "named routes are cleared when reloading" do
+      app("development")
 
       controller :foo, <<-RUBY
         class FooController < ApplicationController
@@ -440,17 +440,17 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':locale/foo', to: 'foo#index', as: 'foo'
         end
       RUBY
 
-      get '/en/foo'
-      assert_equal 'foo', last_response.body
-      assert_equal '/en/foo', Rails.application.routes.url_helpers.foo_path(:locale => 'en')
+      get "/en/foo"
+      assert_equal "foo", last_response.body
+      assert_equal "/en/foo", Rails.application.routes.url_helpers.foo_path(:locale => "en")
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           get ':locale/bar', to: 'bar#index', as: 'foo'
         end
@@ -458,28 +458,28 @@ module ApplicationTests
 
       Rails.application.reload_routes!
 
-      get '/en/foo'
+      get "/en/foo"
       assert_equal 404, last_response.status
 
-      get '/en/bar'
-      assert_equal 'bar', last_response.body
-      assert_equal '/en/bar', Rails.application.routes.url_helpers.foo_path(:locale => 'en')
+      get "/en/bar"
+      assert_equal "bar", last_response.body
+      assert_equal "/en/bar", Rails.application.routes.url_helpers.foo_path(:locale => "en")
     end
 
-    test 'resource routing with irregular inflection' do
-      app_file 'config/initializers/inflection.rb', <<-RUBY
+    test "resource routing with irregular inflection" do
+      app_file "config/initializers/inflection.rb", <<-RUBY
         ActiveSupport::Inflector.inflections do |inflect|
           inflect.irregular 'yazi', 'yazilar'
         end
       RUBY
 
-      app_file 'config/routes.rb', <<-RUBY
+      app_file "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           resources :yazilar
         end
       RUBY
 
-      controller 'yazilar', <<-RUBY
+      controller "yazilar", <<-RUBY
         class YazilarController < ApplicationController
           def index
             render text: 'yazilar#index'
@@ -487,10 +487,10 @@ module ApplicationTests
         end
       RUBY
 
-      get '/yazilars'
+      get "/yazilars"
       assert_equal 404, last_response.status
 
-      get '/yazilar'
+      get "/yazilar"
       assert_equal 200, last_response.status
     end
   end
diff --git a/railties/test/application/runner_test.rb b/railties/test/application/runner_test.rb
index 84d90cc6d7..1c4aa1d4c4 100644
--- a/railties/test/application/runner_test.rb
+++ b/railties/test/application/runner_test.rb
@@ -1,5 +1,5 @@
-require 'isolation/abstract_unit'
-require 'env_helpers'
+require "isolation/abstract_unit"
+require "env_helpers"
 
 module ApplicationTests
   class RunnerTest < ActiveSupport::TestCase
diff --git a/railties/test/application/test_runner_test.rb b/railties/test/application/test_runner_test.rb
index 08759ab5a4..b442891769 100644
--- a/railties/test/application/test_runner_test.rb
+++ b/railties/test/application/test_runner_test.rb
@@ -1,6 +1,6 @@
-require 'isolation/abstract_unit'
-require 'active_support/core_ext/string/strip'
-require 'env_helpers'
+require "isolation/abstract_unit"
+require "active_support/core_ext/string/strip"
+require "env_helpers"
 
 module ApplicationTests
   class TestRunnerTest < ActiveSupport::TestCase
@@ -16,31 +16,31 @@ module ApplicationTests
     end
 
     def test_run_single_file
-      create_test_file :models, 'foo'
-      create_test_file :models, 'bar'
+      create_test_file :models, "foo"
+      create_test_file :models, "bar"
       assert_match "1 runs, 1 assertions, 0 failures", run_test_command("test/models/foo_test.rb")
     end
 
     def test_run_multiple_files
-      create_test_file :models,  'foo'
-      create_test_file :models,  'bar'
+      create_test_file :models,  "foo"
+      create_test_file :models,  "bar"
       assert_match "2 runs, 2 assertions, 0 failures", run_test_command("test/models/foo_test.rb test/models/bar_test.rb")
     end
 
     def test_run_file_with_syntax_error
-      app_file 'test/models/error_test.rb', <<-RUBY
+      app_file "test/models/error_test.rb", <<-RUBY
         require 'test_helper'
         def; end
       RUBY
 
-      error = capture(:stderr) { run_test_command('test/models/error_test.rb') }
+      error = capture(:stderr) { run_test_command("test/models/error_test.rb") }
       assert_match "syntax error", error
     end
 
     def test_run_models
-      create_test_file :models, 'foo'
-      create_test_file :models, 'bar'
-      create_test_file :controllers, 'foobar_controller'
+      create_test_file :models, "foo"
+      create_test_file :models, "bar"
+      create_test_file :controllers, "foobar_controller"
       run_test_command("test/models").tap do |output|
         assert_match "FooTest", output
         assert_match "BarTest", output
@@ -49,9 +49,9 @@ module ApplicationTests
     end
 
     def test_run_helpers
-      create_test_file :helpers, 'foo_helper'
-      create_test_file :helpers, 'bar_helper'
-      create_test_file :controllers, 'foobar_controller'
+      create_test_file :helpers, "foo_helper"
+      create_test_file :helpers, "bar_helper"
+      create_test_file :controllers, "foobar_controller"
       run_test_command("test/helpers").tap do |output|
         assert_match "FooHelperTest", output
         assert_match "BarHelperTest", output
@@ -61,10 +61,10 @@ module ApplicationTests
 
     def test_run_units
       skip "we no longer have the concept of unit tests. Just different directories..."
-      create_test_file :models, 'foo'
-      create_test_file :helpers, 'bar_helper'
-      create_test_file :unit, 'baz_unit'
-      create_test_file :controllers, 'foobar_controller'
+      create_test_file :models, "foo"
+      create_test_file :helpers, "bar_helper"
+      create_test_file :unit, "baz_unit"
+      create_test_file :controllers, "foobar_controller"
       run_test_units_command.tap do |output|
         assert_match "FooTest", output
         assert_match "BarHelperTest", output
@@ -74,9 +74,9 @@ module ApplicationTests
     end
 
     def test_run_controllers
-      create_test_file :controllers, 'foo_controller'
-      create_test_file :controllers, 'bar_controller'
-      create_test_file :models, 'foo'
+      create_test_file :controllers, "foo_controller"
+      create_test_file :controllers, "bar_controller"
+      create_test_file :models, "foo"
       run_test_command("test/controllers").tap do |output|
         assert_match "FooControllerTest", output
         assert_match "BarControllerTest", output
@@ -85,9 +85,9 @@ module ApplicationTests
     end
 
     def test_run_mailers
-      create_test_file :mailers, 'foo_mailer'
-      create_test_file :mailers, 'bar_mailer'
-      create_test_file :models, 'foo'
+      create_test_file :mailers, "foo_mailer"
+      create_test_file :mailers, "bar_mailer"
+      create_test_file :models, "foo"
       run_test_command("test/mailers").tap do |output|
         assert_match "FooMailerTest", output
         assert_match "BarMailerTest", output
@@ -96,9 +96,9 @@ module ApplicationTests
     end
 
     def test_run_jobs
-      create_test_file :jobs, 'foo_job'
-      create_test_file :jobs, 'bar_job'
-      create_test_file :models, 'foo'
+      create_test_file :jobs, "foo_job"
+      create_test_file :jobs, "bar_job"
+      create_test_file :models, "foo"
       run_test_command("test/jobs").tap do |output|
         assert_match "FooJobTest", output
         assert_match "BarJobTest", output
@@ -108,10 +108,10 @@ module ApplicationTests
 
     def test_run_functionals
       skip "we no longer have the concept of functional tests. Just different directories..."
-      create_test_file :mailers, 'foo_mailer'
-      create_test_file :controllers, 'bar_controller'
-      create_test_file :functional, 'baz_functional'
-      create_test_file :models, 'foo'
+      create_test_file :mailers, "foo_mailer"
+      create_test_file :controllers, "bar_controller"
+      create_test_file :functional, "baz_functional"
+      create_test_file :models, "foo"
       run_test_functionals_command.tap do |output|
         assert_match "FooMailerTest", output
         assert_match "BarControllerTest", output
@@ -121,8 +121,8 @@ module ApplicationTests
     end
 
     def test_run_integration
-      create_test_file :integration, 'foo_integration'
-      create_test_file :models, 'foo'
+      create_test_file :integration, "foo_integration"
+      create_test_file :models, "foo"
       run_test_command("test/integration").tap do |output|
         assert_match "FooIntegration", output
         assert_match "1 runs, 1 assertions, 0 failures", output
@@ -132,14 +132,14 @@ module ApplicationTests
     def test_run_all_suites
       suites = [:models, :helpers, :unit, :controllers, :mailers, :functional, :integration, :jobs]
       suites.each { |suite| create_test_file suite, "foo_#{suite}" }
-      run_test_command('') .tap do |output|
+      run_test_command("") .tap do |output|
         suites.each { |suite| assert_match "Foo#{suite.to_s.camelize}Test", output }
         assert_match "8 runs, 8 assertions, 0 failures", output
       end
     end
 
     def test_run_named_test
-      app_file 'test/unit/chu_2_koi_test.rb', <<-RUBY
+      app_file "test/unit/chu_2_koi_test.rb", <<-RUBY
         require 'test_helper'
 
         class Chu2KoiTest < ActiveSupport::TestCase
@@ -153,14 +153,14 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('-n test_rikka test/unit/chu_2_koi_test.rb').tap do |output|
+      run_test_command("-n test_rikka test/unit/chu_2_koi_test.rb").tap do |output|
         assert_match "Rikka", output
         assert_no_match "Sanae", output
       end
     end
 
     def test_run_matched_test
-      app_file 'test/unit/chu_2_koi_test.rb', <<-RUBY
+      app_file "test/unit/chu_2_koi_test.rb", <<-RUBY
         require 'test_helper'
 
         class Chu2KoiTest < ActiveSupport::TestCase
@@ -174,7 +174,7 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('-n /rikka/ test/unit/chu_2_koi_test.rb').tap do |output|
+      run_test_command("-n /rikka/ test/unit/chu_2_koi_test.rb").tap do |output|
         assert_match "Rikka", output
         assert_no_match "Sanae", output
       end
@@ -195,14 +195,14 @@ module ApplicationTests
     def test_run_with_model
       skip "These feel a bit odd. Not sure we should keep supporting them."
       create_model_with_fixture
-      create_fixture_test 'models', 'user'
+      create_fixture_test "models", "user"
       assert_match "3 users", run_task(["test models/user"])
       assert_match "3 users", run_task(["test app/models/user.rb"])
     end
 
     def test_run_different_environment_using_env_var
       skip "no longer possible. Running tests in a different environment should be explicit"
-      app_file 'test/unit/env_test.rb', <<-RUBY
+      app_file "test/unit/env_test.rb", <<-RUBY
         require 'test_helper'
 
         class EnvTest < ActiveSupport::TestCase
@@ -212,14 +212,14 @@ module ApplicationTests
         end
       RUBY
 
-      ENV['RAILS_ENV'] = 'development'
-      assert_match "development", run_test_command('test/unit/env_test.rb')
+      ENV["RAILS_ENV"] = "development"
+      assert_match "development", run_test_command("test/unit/env_test.rb")
     end
 
     def test_run_in_test_environment_by_default
       create_env_test
 
-      assert_match "Current Environment: test", run_test_command('test/unit/env_test.rb')
+      assert_match "Current Environment: test", run_test_command("test/unit/env_test.rb")
     end
 
     def test_run_different_environment
@@ -231,27 +231,27 @@ module ApplicationTests
 
     def test_generated_scaffold_works_with_rails_test
       create_scaffold
-      assert_match "0 failures, 0 errors, 0 skips", run_test_command('')
+      assert_match "0 failures, 0 errors, 0 skips", run_test_command("")
     end
 
     def test_generated_controller_works_with_rails_test
       create_controller
-      assert_match "0 failures, 0 errors, 0 skips", run_test_command('')
+      assert_match "0 failures, 0 errors, 0 skips", run_test_command("")
     end
 
     def test_run_multiple_folders
-      create_test_file :models, 'account'
-      create_test_file :controllers, 'accounts_controller'
+      create_test_file :models, "account"
+      create_test_file :controllers, "accounts_controller"
 
-      run_test_command('test/models test/controllers').tap do |output|
-        assert_match 'AccountTest', output
-        assert_match 'AccountsControllerTest', output
-        assert_match '2 runs, 2 assertions, 0 failures, 0 errors, 0 skips', output
+      run_test_command("test/models test/controllers").tap do |output|
+        assert_match "AccountTest", output
+        assert_match "AccountsControllerTest", output
+        assert_match "2 runs, 2 assertions, 0 failures, 0 errors, 0 skips", output
       end
     end
 
     def test_run_with_ruby_command
-      app_file 'test/models/post_test.rb', <<-RUBY
+      app_file "test/models/post_test.rb", <<-RUBY
         require 'test_helper'
 
         class PostTest < ActiveSupport::TestCase
@@ -264,15 +264,15 @@ module ApplicationTests
 
       Dir.chdir(app_path) do
         `ruby -Itest test/models/post_test.rb`.tap do |output|
-          assert_match 'PostTest', output
-          assert_no_match 'is already defined in', output
+          assert_match "PostTest", output
+          assert_no_match "is already defined in", output
         end
       end
     end
 
     def test_mix_files_and_line_filters
-      create_test_file :models, 'account'
-      app_file 'test/models/post_test.rb', <<-RUBY
+      create_test_file :models, "account"
+      app_file "test/models/post_test.rb", <<-RUBY
         require 'test_helper'
 
         class PostTest < ActiveSupport::TestCase
@@ -287,15 +287,15 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('test/models/account_test.rb test/models/post_test.rb:4').tap do |output|
-        assert_match 'AccountTest', output
-        assert_match 'PostTest', output
-        assert_match '2 runs, 2 assertions', output
+      run_test_command("test/models/account_test.rb test/models/post_test.rb:4").tap do |output|
+        assert_match "AccountTest", output
+        assert_match "PostTest", output
+        assert_match "2 runs, 2 assertions", output
       end
     end
 
     def test_more_than_one_line_filter
-      app_file 'test/models/post_test.rb', <<-RUBY
+      app_file "test/models/post_test.rb", <<-RUBY
         require 'test_helper'
 
         class PostTest < ActiveSupport::TestCase
@@ -315,15 +315,15 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('test/models/post_test.rb:4:9').tap do |output|
-        assert_match 'PostTest:FirstFilter', output
-        assert_match 'PostTest:SecondFilter', output
-        assert_match '2 runs, 2 assertions', output
+      run_test_command("test/models/post_test.rb:4:9").tap do |output|
+        assert_match "PostTest:FirstFilter", output
+        assert_match "PostTest:SecondFilter", output
+        assert_match "2 runs, 2 assertions", output
       end
     end
 
     def test_more_than_one_line_filter_with_multiple_files
-      app_file 'test/models/account_test.rb', <<-RUBY
+      app_file "test/models/account_test.rb", <<-RUBY
         require 'test_helper'
 
         class AccountTest < ActiveSupport::TestCase
@@ -343,7 +343,7 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'test/models/post_test.rb', <<-RUBY
+      app_file "test/models/post_test.rb", <<-RUBY
         require 'test_helper'
 
         class PostTest < ActiveSupport::TestCase
@@ -363,27 +363,27 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('test/models/account_test.rb:4:9 test/models/post_test.rb:4:9').tap do |output|
-        assert_match 'AccountTest:FirstFilter', output
-        assert_match 'AccountTest:SecondFilter', output
-        assert_match 'PostTest:FirstFilter', output
-        assert_match 'PostTest:SecondFilter', output
-        assert_match '4 runs, 4 assertions', output
+      run_test_command("test/models/account_test.rb:4:9 test/models/post_test.rb:4:9").tap do |output|
+        assert_match "AccountTest:FirstFilter", output
+        assert_match "AccountTest:SecondFilter", output
+        assert_match "PostTest:FirstFilter", output
+        assert_match "PostTest:SecondFilter", output
+        assert_match "4 runs, 4 assertions", output
       end
     end
 
     def test_multiple_line_filters
-      create_test_file :models, 'account'
-      create_test_file :models, 'post'
+      create_test_file :models, "account"
+      create_test_file :models, "post"
 
-      run_test_command('test/models/account_test.rb:4 test/models/post_test.rb:4').tap do |output|
-        assert_match 'AccountTest', output
-        assert_match 'PostTest', output
+      run_test_command("test/models/account_test.rb:4 test/models/post_test.rb:4").tap do |output|
+        assert_match "AccountTest", output
+        assert_match "PostTest", output
       end
     end
 
     def test_line_filters_trigger_only_one_runnable
-      app_file 'test/models/post_test.rb', <<-RUBY
+      app_file "test/models/post_test.rb", <<-RUBY
         require 'test_helper'
 
         class PostTest < ActiveSupport::TestCase
@@ -400,14 +400,14 @@ module ApplicationTests
       RUBY
 
       # Pass seed guaranteeing failure.
-      run_test_command('test/models/post_test.rb:4 --seed 30410').tap do |output|
-        assert_no_match 'ran second runnable', output
-        assert_match '1 runs, 1 assertions', output
+      run_test_command("test/models/post_test.rb:4 --seed 30410").tap do |output|
+        assert_no_match "ran second runnable", output
+        assert_match "1 runs, 1 assertions", output
       end
     end
 
     def test_line_filter_with_minitest_string_filter
-      app_file 'test/models/post_test.rb', <<-RUBY
+      app_file "test/models/post_test.rb", <<-RUBY
         require 'test_helper'
 
         class PostTest < ActiveSupport::TestCase
@@ -423,128 +423,128 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('test/models/post_test.rb:4 -n test_by_name').tap do |output|
-        assert_match 'by line', output
-        assert_match 'by name', output
-        assert_match '2 runs, 2 assertions', output
+      run_test_command("test/models/post_test.rb:4 -n test_by_name").tap do |output|
+        assert_match "by line", output
+        assert_match "by name", output
+        assert_match "2 runs, 2 assertions", output
       end
     end
 
     def test_shows_filtered_backtrace_by_default
       create_backtrace_test
 
-      assert_match 'Rails::BacktraceCleaner', run_test_command('test/unit/backtrace_test.rb')
+      assert_match "Rails::BacktraceCleaner", run_test_command("test/unit/backtrace_test.rb")
     end
 
     def test_backtrace_option
       create_backtrace_test
 
-      assert_match 'Minitest::BacktraceFilter', run_test_command('test/unit/backtrace_test.rb -b')
-      assert_match 'Minitest::BacktraceFilter',
-        run_test_command('test/unit/backtrace_test.rb --backtrace')
+      assert_match "Minitest::BacktraceFilter", run_test_command("test/unit/backtrace_test.rb -b")
+      assert_match "Minitest::BacktraceFilter",
+        run_test_command("test/unit/backtrace_test.rb --backtrace")
     end
 
     def test_show_full_backtrace_using_backtrace_environment_variable
       create_backtrace_test
 
-      switch_env 'BACKTRACE', 'true' do
-        assert_match 'Minitest::BacktraceFilter', run_test_command('test/unit/backtrace_test.rb')
+      switch_env "BACKTRACE", "true" do
+        assert_match "Minitest::BacktraceFilter", run_test_command("test/unit/backtrace_test.rb")
       end
     end
 
     def test_run_app_without_rails_loaded
       # Simulate a real Rails app boot.
-      app_file 'config/boot.rb', <<-RUBY
+      app_file "config/boot.rb", <<-RUBY
         ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
 
         require 'bundler/setup' # Set up gems listed in the Gemfile.
       RUBY
 
-      assert_match '0 runs, 0 assertions', run_test_command('')
+      assert_match "0 runs, 0 assertions", run_test_command("")
     end
 
     def test_output_inline_by_default
-      create_test_file :models, 'post', pass: false
+      create_test_file :models, "post", pass: false
 
-      output = run_test_command('test/models/post_test.rb')
+      output = run_test_command("test/models/post_test.rb")
       expect = %r{Running:\n\nPostTest\nF\n\nFailure:\nPostTest#test_truth \[[^\]]+test/models/post_test.rb:6\]:\nwups!\n\nbin/rails test test/models/post_test.rb:4\n\n\n\n}
       assert_match expect, output
     end
 
     def test_only_inline_failure_output
-      create_test_file :models, 'post', pass: false
+      create_test_file :models, "post", pass: false
 
-      output = run_test_command('test/models/post_test.rb')
+      output = run_test_command("test/models/post_test.rb")
       assert_match %r{Finished in.*\n\n1 runs, 1 assertions}, output
     end
 
     def test_fail_fast
-      create_test_file :models, 'post', pass: false
+      create_test_file :models, "post", pass: false
 
       assert_match(/Interrupt/,
-        capture(:stderr) { run_test_command('test/models/post_test.rb --fail-fast') })
+        capture(:stderr) { run_test_command("test/models/post_test.rb --fail-fast") })
     end
 
     def test_raise_error_when_specified_file_does_not_exist
-      error = capture(:stderr) { run_test_command('test/not_exists.rb') }
+      error = capture(:stderr) { run_test_command("test/not_exists.rb") }
       assert_match(%r{cannot load such file.+test/not_exists\.rb}, error)
     end
 
     def test_pass_TEST_env_on_rake_test
-      create_test_file :models, 'account'
-      create_test_file :models, 'post', pass: false
+      create_test_file :models, "account"
+      create_test_file :models, "post", pass: false
       # This specifically verifies TEST for backwards compatibility with rake test
       # as bin/rails test already supports running tests from a single file more cleanly.
       output =  Dir.chdir(app_path) { `bin/rake test TEST=test/models/post_test.rb` }
 
       assert_match "PostTest", output, "passing TEST= should run selected test"
       assert_no_match "AccountTest", output, "passing TEST= should only run selected test"
-      assert_match '1 runs, 1 assertions', output
+      assert_match "1 runs, 1 assertions", output
     end
 
     def test_pass_rake_options
-      create_test_file :models, 'account'
+      create_test_file :models, "account"
       output =  Dir.chdir(app_path) { `bin/rake --rakefile Rakefile --trace=stdout test` }
 
-      assert_match '1 runs, 1 assertions', output
-      assert_match 'Execute test', output
+      assert_match "1 runs, 1 assertions", output
+      assert_match "Execute test", output
     end
 
     def test_rails_db_create_all_restores_db_connection
-      create_test_file :models, 'account'
+      create_test_file :models, "account"
       output =  Dir.chdir(app_path) { `bin/rails db:create:all db:migrate && echo ".tables" | rails dbconsole` }
       assert_match "ar_internal_metadata", output, "tables should be dumped"
     end
 
     def test_rails_db_create_all_restores_db_connection_after_drop
-      create_test_file :models, 'account'
+      create_test_file :models, "account"
       Dir.chdir(app_path) { `bin/rails db:create:all` } # create all to avoid warnings
       output =  Dir.chdir(app_path) { `bin/rails db:drop:all db:create:all db:migrate && echo ".tables" | rails dbconsole` }
       assert_match "ar_internal_metadata", output, "tables should be dumped"
     end
 
     def test_rake_passes_TESTOPTS_to_minitest
-      create_test_file :models, 'account'
+      create_test_file :models, "account"
       output =  Dir.chdir(app_path) { `bin/rake test TESTOPTS=-v` }
       assert_match "AccountTest#test_truth", output, "passing TEST= should run selected test"
     end
 
     def test_rake_passes_multiple_TESTOPTS_to_minitest
-      create_test_file :models, 'account'
+      create_test_file :models, "account"
       output =  Dir.chdir(app_path) { `bin/rake test TESTOPTS='-v --seed=1234'` }
       assert_match "AccountTest#test_truth", output, "passing TEST= should run selected test"
       assert_match "seed=1234", output, "passing TEST= should run selected test"
     end
 
     private
-      def run_test_command(arguments = 'test/unit/test_test.rb')
+      def run_test_command(arguments = "test/unit/test_test.rb")
         Dir.chdir(app_path) { `bin/rails t #{arguments}` }
       end
 
       def create_model_with_fixture
-        script 'generate model user name:string'
+        script "generate model user name:string"
 
-        app_file 'test/fixtures/users.yml', <<-YAML.strip_heredoc
+        app_file "test/fixtures/users.yml", <<-YAML.strip_heredoc
           vampire:
             id: 1
             name: Koyomi Araragi
@@ -559,7 +559,7 @@ module ApplicationTests
         run_migration
       end
 
-      def create_fixture_test(path = :unit, name = 'test')
+      def create_fixture_test(path = :unit, name = "test")
         app_file "test/#{path}/#{name}_test.rb", <<-RUBY
           require 'test_helper'
 
@@ -572,7 +572,7 @@ module ApplicationTests
       end
 
       def create_backtrace_test
-        app_file 'test/unit/backtrace_test.rb', <<-RUBY
+        app_file "test/unit/backtrace_test.rb", <<-RUBY
           require 'test_helper'
 
           class BacktraceTest < ActiveSupport::TestCase
@@ -584,10 +584,10 @@ module ApplicationTests
       end
 
       def create_schema
-        app_file 'db/schema.rb', ''
+        app_file "db/schema.rb", ""
       end
 
-      def create_test_file(path = :unit, name = 'test', pass: true)
+      def create_test_file(path = :unit, name = "test", pass: true)
         app_file "test/#{path}/#{name}_test.rb", <<-RUBY
           require 'test_helper'
 
@@ -601,7 +601,7 @@ module ApplicationTests
       end
 
       def create_env_test
-        app_file 'test/unit/env_test.rb', <<-RUBY
+        app_file "test/unit/env_test.rb", <<-RUBY
           require 'test_helper'
 
           class EnvTest < ActiveSupport::TestCase
@@ -613,13 +613,13 @@ module ApplicationTests
       end
 
       def create_scaffold
-        script 'generate scaffold user name:string'
-        Dir.chdir(app_path) { File.exist?('app/models/user.rb') }
+        script "generate scaffold user name:string"
+        Dir.chdir(app_path) { File.exist?("app/models/user.rb") }
         run_migration
       end
 
       def create_controller
-        script 'generate controller admin/dashboard index'
+        script "generate controller admin/dashboard index"
       end
 
       def run_migration
diff --git a/railties/test/application/test_test.rb b/railties/test/application/test_test.rb
index 1e9d35287e..ef65c7a893 100644
--- a/railties/test/application/test_test.rb
+++ b/railties/test/application/test_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class TestTest < ActiveSupport::TestCase
@@ -13,7 +13,7 @@ module ApplicationTests
     end
 
     test "truth" do
-      app_file 'test/unit/foo_test.rb', <<-RUBY
+      app_file "test/unit/foo_test.rb", <<-RUBY
         require 'test_helper'
 
         class FooTest < ActiveSupport::TestCase
@@ -23,20 +23,20 @@ module ApplicationTests
         end
       RUBY
 
-      assert_successful_test_run 'unit/foo_test.rb'
+      assert_successful_test_run "unit/foo_test.rb"
     end
 
     test "integration test" do
-      controller 'posts', <<-RUBY
+      controller "posts", <<-RUBY
         class PostsController < ActionController::Base
         end
       RUBY
 
-      app_file 'app/views/posts/index.html.erb', <<-HTML
+      app_file "app/views/posts/index.html.erb", <<-HTML
         Posts#index
       HTML
 
-      app_file 'test/integration/posts_test.rb', <<-RUBY
+      app_file "test/integration/posts_test.rb", <<-RUBY
         require 'test_helper'
 
         class PostsTest < ActionDispatch::IntegrationTest
@@ -48,11 +48,11 @@ module ApplicationTests
         end
       RUBY
 
-      assert_successful_test_run 'integration/posts_test.rb'
+      assert_successful_test_run "integration/posts_test.rb"
     end
 
     test "enable full backtraces on test failures" do
-      app_file 'test/unit/failing_test.rb', <<-RUBY
+      app_file "test/unit/failing_test.rb", <<-RUBY
         require 'test_helper'
 
         class FailingTest < ActiveSupport::TestCase
@@ -62,16 +62,16 @@ module ApplicationTests
         end
       RUBY
 
-      output = run_test_file('unit/failing_test.rb', env: { "BACKTRACE" => "1" })
+      output = run_test_file("unit/failing_test.rb", env: { "BACKTRACE" => "1" })
       assert_match %r{test/unit/failing_test\.rb}, output
       assert_match %r{test/unit/failing_test\.rb:4}, output
     end
 
     test "ruby schema migrations" do
-      output  = script('generate model user name:string')
+      output  = script("generate model user name:string")
       version = output.match(/(\d+)_create_users\.rb/)[1]
 
-      app_file 'test/models/user_test.rb', <<-RUBY
+      app_file "test/models/user_test.rb", <<-RUBY
         require 'test_helper'
 
         class UserTest < ActiveSupport::TestCase
@@ -80,11 +80,11 @@ module ApplicationTests
           end
         end
       RUBY
-      app_file 'db/schema.rb', ''
+      app_file "db/schema.rb", ""
 
       assert_unsuccessful_run "models/user_test.rb", "Migrations are pending"
 
-      app_file 'db/schema.rb', <<-RUBY
+      app_file "db/schema.rb", <<-RUBY
         ActiveRecord::Schema.define(version: #{version}) do
           create_table :users do |t|
             t.string :name
@@ -92,7 +92,7 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/initializers/disable_maintain_test_schema.rb', <<-RUBY
+      app_file "config/initializers/disable_maintain_test_schema.rb", <<-RUBY
         Rails.application.config.active_record.maintain_test_schema = false
       RUBY
 
@@ -100,15 +100,15 @@ module ApplicationTests
 
       File.delete "#{app_path}/config/initializers/disable_maintain_test_schema.rb"
 
-      result = assert_successful_test_run('models/user_test.rb')
+      result = assert_successful_test_run("models/user_test.rb")
       assert !result.include?("create_table(:users)")
     end
 
     test "sql structure migrations" do
-      output  = script('generate model user name:string')
+      output  = script("generate model user name:string")
       version = output.match(/(\d+)_create_users\.rb/)[1]
 
-      app_file 'test/models/user_test.rb', <<-RUBY
+      app_file "test/models/user_test.rb", <<-RUBY
         require 'test_helper'
 
         class UserTest < ActiveSupport::TestCase
@@ -118,21 +118,21 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'db/structure.sql', ''
-      app_file 'config/initializers/enable_sql_schema_format.rb', <<-RUBY
+      app_file "db/structure.sql", ""
+      app_file "config/initializers/enable_sql_schema_format.rb", <<-RUBY
         Rails.application.config.active_record.schema_format = :sql
       RUBY
 
       assert_unsuccessful_run "models/user_test.rb", "Migrations are pending"
 
-      app_file 'db/structure.sql', <<-SQL
+      app_file "db/structure.sql", <<-SQL
         CREATE TABLE "schema_migrations" ("version" varchar(255) NOT NULL);
         CREATE UNIQUE INDEX "unique_schema_migrations" ON "schema_migrations" ("version");
         CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar(255));
         INSERT INTO schema_migrations (version) VALUES ('#{version}');
       SQL
 
-      app_file 'config/initializers/disable_maintain_test_schema.rb', <<-RUBY
+      app_file "config/initializers/disable_maintain_test_schema.rb", <<-RUBY
         Rails.application.config.active_record.maintain_test_schema = false
       RUBY
 
@@ -140,14 +140,14 @@ module ApplicationTests
 
       File.delete "#{app_path}/config/initializers/disable_maintain_test_schema.rb"
 
-      assert_successful_test_run('models/user_test.rb')
+      assert_successful_test_run("models/user_test.rb")
     end
 
     test "sql structure migrations when adding column to existing table" do
-      output_1  = script('generate model user name:string')
+      output_1  = script("generate model user name:string")
       version_1 = output_1.match(/(\d+)_create_users\.rb/)[1]
 
-      app_file 'test/models/user_test.rb', <<-RUBY
+      app_file "test/models/user_test.rb", <<-RUBY
         require 'test_helper'
         class UserTest < ActiveSupport::TestCase
           test "user" do
@@ -156,23 +156,23 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'config/initializers/enable_sql_schema_format.rb', <<-RUBY
+      app_file "config/initializers/enable_sql_schema_format.rb", <<-RUBY
         Rails.application.config.active_record.schema_format = :sql
       RUBY
 
-      app_file 'db/structure.sql', <<-SQL
+      app_file "db/structure.sql", <<-SQL
         CREATE TABLE "schema_migrations" ("version" varchar(255) NOT NULL);
         CREATE UNIQUE INDEX "unique_schema_migrations" ON "schema_migrations" ("version");
         CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar(255));
         INSERT INTO schema_migrations (version) VALUES ('#{version_1}');
       SQL
 
-      assert_successful_test_run('models/user_test.rb')
+      assert_successful_test_run("models/user_test.rb")
 
-      output_2  = script('generate migration add_email_to_users')
+      output_2  = script("generate migration add_email_to_users")
       version_2 = output_2.match(/(\d+)_add_email_to_users\.rb/)[1]
 
-      app_file 'test/models/user_test.rb', <<-RUBY
+      app_file "test/models/user_test.rb", <<-RUBY
         require 'test_helper'
 
         class UserTest < ActiveSupport::TestCase
@@ -182,7 +182,7 @@ module ApplicationTests
         end
       RUBY
 
-      app_file 'db/structure.sql', <<-SQL
+      app_file "db/structure.sql", <<-SQL
         CREATE TABLE "schema_migrations" ("version" varchar(255) NOT NULL);
         CREATE UNIQUE INDEX "unique_schema_migrations" ON "schema_migrations" ("version");
         CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar(255), "email" varchar(255));
@@ -190,17 +190,17 @@ module ApplicationTests
         INSERT INTO schema_migrations (version) VALUES ('#{version_2}');
       SQL
 
-      assert_successful_test_run('models/user_test.rb')
+      assert_successful_test_run("models/user_test.rb")
     end
 
     # TODO: would be nice if we could detect the schema change automatically.
     # For now, the user has to synchronize the schema manually.
     # This test-case serves as a reminder for this use-case.
     test "manually synchronize test schema after rollback" do
-      output  = script('generate model user name:string')
+      output  = script("generate model user name:string")
       version = output.match(/(\d+)_create_users\.rb/)[1]
 
-      app_file 'test/models/user_test.rb', <<-RUBY
+      app_file "test/models/user_test.rb", <<-RUBY
         require 'test_helper'
 
         class UserTest < ActiveSupport::TestCase
@@ -209,7 +209,7 @@ module ApplicationTests
           end
         end
       RUBY
-      app_file 'db/schema.rb', <<-RUBY
+      app_file "db/schema.rb", <<-RUBY
         ActiveRecord::Schema.define(version: #{version}) do
           create_table :users do |t|
             t.string :name
@@ -220,7 +220,7 @@ module ApplicationTests
       assert_successful_test_run "models/user_test.rb"
 
       # Simulate `db:rollback` + edit of the migration file + `db:migrate`
-      app_file 'db/schema.rb', <<-RUBY
+      app_file "db/schema.rb", <<-RUBY
         ActiveRecord::Schema.define(version: #{version}) do
           create_table :users do |t|
             t.string :name
@@ -240,10 +240,10 @@ Expected: ["id", "name"]
     end
 
     test "hooks for plugins" do
-      output  = script('generate model user name:string')
+      output  = script("generate model user name:string")
       version = output.match(/(\d+)_create_users\.rb/)[1]
 
-      app_file 'lib/tasks/hooks.rake', <<-RUBY
+      app_file "lib/tasks/hooks.rake", <<-RUBY
         task :before_hook do
           has_user_table = ActiveRecord::Base.connection.table_exists?('users')
           puts "before: " + has_user_table.to_s
@@ -258,7 +258,7 @@ Expected: ["id", "name"]
           Rake::Task[:after_hook].invoke
         end
       RUBY
-      app_file 'test/models/user_test.rb', <<-RUBY
+      app_file "test/models/user_test.rb", <<-RUBY
         require 'test_helper'
         class UserTest < ActiveSupport::TestCase
           test "user" do
@@ -268,7 +268,7 @@ Expected: ["id", "name"]
       RUBY
 
       # Simulate `db:migrate`
-      app_file 'db/schema.rb', <<-RUBY
+      app_file "db/schema.rb", <<-RUBY
         ActiveRecord::Schema.define(version: #{version}) do
           create_table :users do |t|
             t.string :name
diff --git a/railties/test/application/url_generation_test.rb b/railties/test/application/url_generation_test.rb
index 6700323199..ced6c6b0a6 100644
--- a/railties/test/application/url_generation_test.rb
+++ b/railties/test/application/url_generation_test.rb
@@ -1,4 +1,4 @@
-require 'isolation/abstract_unit'
+require "isolation/abstract_unit"
 
 module ApplicationTests
   class UrlGenerationTest < ActiveSupport::TestCase
@@ -35,7 +35,7 @@ module ApplicationTests
         get "/" => "omg#index", as: :omg
       end
 
-      require 'rack/test'
+      require "rack/test"
       extend Rack::Test::Methods
 
       get "/"
@@ -47,7 +47,7 @@ module ApplicationTests
       require "action_controller/railtie"
       require "action_view/railtie"
 
-      relative_url = '/hello'
+      relative_url = "/hello"
       ENV["RAILS_RELATIVE_URL_ROOT"] = relative_url
       app = Class.new(Rails::Application)
       assert_equal relative_url, app.routes.relative_url_root