enables the evented monitor in new applications

railties/CHANGELOG.md

@@ -1,3 +1,8 @@
*   New applications are generated with the evented file system monitor enabled
    on Linux and Mac OS X.

    *Xavier Noria*

*   Add dummy files for apple-touch-icon.png and apple-touch-icon.png. GH#23427

    *Alexey Zabelin*

railties/lib/rails/generators/app_base.rb

@@ -390,6 +390,10 @@ def spring_install?
        !options[:skip_spring] && !options.dev? && Process.respond_to?(:fork) && !RUBY_PLATFORM.include?("cygwin")
      end

      def os_supports_listen_out_of_the_box?
        RbConfig::CONFIG['host_os'] =~ /darwin|linux/
      end

      def run_bundle
        bundle_command('install') if bundle_install?
      end

railties/lib/rails/generators/rails/app/templates/Gemfile

@@ -38,6 +38,9 @@ group :development do
  gem 'web-console', '~> 3.0'
  <%- end -%>
<%- end -%>
<% if os_supports_listen_out_of_the_box? -%>
  gem 'listen', '~> 3.0.5'
<% end -%>
<% if spring_install? -%>
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'

railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt

@@ -58,5 +58,5 @@ Rails.application.configure do

  # Use an evented file watcher to asynchronously detect changes in source code,
  # routes, locales, etc. This feature depends on the listen gem.
  # config.file_watcher = ActiveSupport::EventedFileUpdateChecker
  <%= '# ' unless os_supports_listen_out_of_the_box? %>config.file_watcher = ActiveSupport::EventedFileUpdateChecker
end

railties/test/generators/app_generator_test.rb

@@ -479,6 +479,28 @@ def test_inclusion_of_a_debugger
    end
  end

  def test_inclusion_of_listen_related_gems
    run_generator
    if RbConfig::CONFIG['host_os'] =~ /darwin|linux/
      assert_gem 'listen'
    else
      assert_file 'Gemfile' do |content|
        assert_no_match(/listen/, content)
      end
    end
  end

  def test_evented_file_update_checker_config
    run_generator
    assert_file 'config/environments/development.rb' do |content|
      if RbConfig::CONFIG['host_os'] =~ /darwin|linux/
        assert_match(/^\s*config.file_watcher = ActiveSupport::EventedFileUpdateChecker/, content)
      else
        assert_match(/^\s*# config.file_watcher = ActiveSupport::EventedFileUpdateChecker/, content)
      end
    end
  end

  def test_template_from_dir_pwd
    FileUtils.cd(Rails.root)
    assert_match(/It works from file!/, run_generator([destination_root, "-m", "lib/template.rb"]))