application template respects Gemfile entries

railties/lib/rails/generators/rails/app/templates/app/views/layouts/application.html.erb.tt

@@ -5,8 +5,13 @@
   <%- if options[:skip_javascript] -%>
   <%%= stylesheet_link_tag    "application", media: "all" %>
   <%- else -%>
+    <%- if gemfile_entries.any? { |m| m.name == "turbolinks" } -%>
   <%%= stylesheet_link_tag    "application", media: "all", "data-turbolinks-track" => true %>
   <%%= javascript_include_tag "application", "data-turbolinks-track" => true %>
+    <%- else -%>
+  <%%= stylesheet_link_tag    "application", media: "all" %>
+  <%%= javascript_include_tag "application" %>
+    <%- end -%>
   <%- end -%>
   <%%= csrf_meta_tags %>
 </head>

railties/test/generators/app_generator_test.rb

@@ -182,6 +182,26 @@ class AppGeneratorTest < Rails::Generators::TestCase
     template.unlink
   end
 
+  def test_application_html_checks_gems
+    template = Tempfile.open 'my_template'
+    template.puts 'add_gem_entry_filter { |gem| gem.name != "turbolinks" }'
+    template.flush
+
+    run_generator([destination_root, "-m", template.path])
+    assert_file "Gemfile" do |contents|
+      assert_no_match 'turbolinks', contents
+    end
+    assert_file "Gemfile" do |contents|
+      assert_no_match 'turbolinks', contents
+    end
+    assert_file "app/views/layouts/application.html.erb" do |contents|
+      assert_no_match 'turbolinks', contents
+    end
+  ensure
+    template.close
+    template.unlink
+  end
+
   def test_config_another_database
     run_generator([destination_root, "-d", "mysql"])
     assert_file "config/database.yml", /mysql/