Install Spring preloader when generating new applications

railties/CHANGELOG.md

+*   The [Spring application
+    preloader](https://github.com/jonleighton/spring) is now installed
+    by default for new applications. It uses the development group of
+    the Gemfile, so will not be installed in production.
+
+    *Jon Leighton*
+
 *   Uses .railsrc while creating new plugin if it is available.
     Fixes #10700.
 

railties/lib/rails/generators/app_base.rb

@@ -47,6 +47,9 @@ def self.add_shared_options_for(name)
         class_option :skip_sprockets,     type: :boolean, aliases: '-S', default: false,
                                           desc: 'Skip Sprockets files'
 
+        class_option :skip_spring,        type: :boolean, default: false,
+                                          desc: "Don't install Spring application preloader"
+
         class_option :database,           type: :string, aliases: '-d', default: 'sqlite3',
                                           desc: "Preconfigure for selected database (options: #{DATABASES.join('/')})"
 
@@ -109,6 +112,7 @@ def gemfile_entries
           jbuilder_gemfile_entry,
           sdoc_gemfile_entry,
           platform_dependent_gemfile_entry,
+          spring_gemfile_entry,
           @extra_entries].flatten.find_all(&@gem_filter)
       end
 
@@ -365,6 +369,12 @@ def javascript_runtime_gemfile_entry
         end
       end
 
+      def spring_gemfile_entry
+        return [] unless spring_install?
+        comment = 'Spring speeds up development by keeping your application running in the background. Read more: https://github.com/jonleighton/spring'
+        GemfileEntry.new('spring', nil, comment, group: :development)
+      end
+
       def bundle_command(command)
         say_status :run, "bundle #{command}"
 
@@ -388,8 +398,22 @@ def bundle_command(command)
         end
       end
 
+      def bundle_install?
+        !(options[:skip_gemfile] || options[:skip_bundle] || options[:pretend])
+      end
+
+      def spring_install?
+        !options[:skip_spring] && Process.respond_to?(:fork)
+      end
+
       def run_bundle
-        bundle_command('install') unless options[:skip_gemfile] || options[:skip_bundle] || options[:pretend]
+        bundle_command('install') if bundle_install?
+      end
+
+      def generate_spring_binstubs
+        if bundle_install? && spring_install?
+          bundle_command("exec spring binstub --all")
+        end
       end
 
       def empty_directory_with_keep_file(destination, config = {})

railties/lib/rails/generators/rails/app/app_generator.rb

@@ -237,6 +237,7 @@ def delete_js_folder_skipping_javascript
 
       public_task :run_bundle
       public_task :replay_template
+      public_task :generate_spring_binstubs
 
     protected
 

railties/test/generators/app_generator_test.rb

@@ -437,6 +437,34 @@ def test_application_name_with_spaces
     assert_file "foo bar/config/initializers/session_store.rb", /key: '_foo_bar/
   end
 
+  def test_spring
+    run_generator
+    assert_file "Gemfile", /gem 'spring'/
+  end
+
+  def test_spring_binstubs
+    generator.stubs(:bundle_command).with('install')
+    generator.expects(:bundle_command).with('exec spring binstub --all').once
+    quietly { generator.invoke_all }
+  end
+
+  def test_spring_no_fork
+    Process.stubs(:respond_to?).with(:fork).returns(false)
+    run_generator
+
+    assert_file "Gemfile" do |content|
+      assert_no_match(/spring/, content)
+    end
+  end
+
+  def test_skip_spring
+    run_generator [destination_root, "--skip-spring"]
+
+    assert_file "Gemfile" do |content|
+      assert_no_match(/spring/, content)
+    end
+  end
+
 protected
 
   def action(*args, &block)

railties/test/generators/shared_generator_tests.rb

@@ -26,11 +26,17 @@ def test_skeleton_is_created
     default_files.each { |path| assert_file path }
   end
 
-  def test_generation_runs_bundle_install
-    generator([destination_root]).expects(:bundle_command).with('install').once
+  def assert_generates_with_bundler(options = {})
+    generator([destination_root], options)
+    generator.expects(:bundle_command).with('install').once
+    generator.stubs(:bundle_command).with('exec spring binstub --all')
     quietly { generator.invoke_all }
   end
 
+  def test_generation_runs_bundle_install
+    assert_generates_with_bundler
+  end
+
   def test_plugin_new_generate_pretend
     run_generator ["testapp", "--pretend"]
     default_files.each{ |path| assert_no_file File.join("testapp",path) }
@@ -96,15 +102,13 @@ def test_template_is_executed_when_supplied_an_https_path
   end
 
   def test_dev_option
-    generator([destination_root], dev: true).expects(:bundle_command).with('install').once
-    quietly { generator.invoke_all }
+    assert_generates_with_bundler dev: true
     rails_path = File.expand_path('../../..', Rails.root)
     assert_file 'Gemfile', /^gem\s+["']rails["'],\s+path:\s+["']#{Regexp.escape(rails_path)}["']$/
   end
 
   def test_edge_option
-    generator([destination_root], edge: true).expects(:bundle_command).with('install').once
-    quietly { generator.invoke_all }
+    assert_generates_with_bundler edge: true
     assert_file 'Gemfile', %r{^gem\s+["']rails["'],\s+github:\s+["']#{Regexp.escape("rails/rails")}["']$}
   end