Don't add bin/rubocop if rubocop is not in Gemfile

Author: etiennebarrie

railties/lib/rails/commands/app/update_command.rb

@@ -69,7 +69,8 @@ def generator_options
               skip_action_mailbox: !defined?(ActionMailbox::Engine),
               skip_action_text:    !defined?(ActionText::Engine),
               skip_action_cable:   !defined?(ActionCable::Engine),
-              skip_brakeman:       skip_brakeman?,
+              skip_brakeman:       skip_gem?("brakeman"),
+              skip_rubocop:        skip_gem?("rubocop"),
               skip_test:           !defined?(Rails::TestUnitRailtie),
               skip_system_test:    Rails.application.config.generators.system_tests.nil?,
               asset_pipeline:      asset_pipeline,
@@ -89,8 +90,8 @@ def asset_pipeline
             end
           end
 
-          def skip_brakeman?
-            require "brakeman"
+          def skip_gem?(gem_name)
+            gem gem_name
             false
           rescue LoadError
             true

railties/test/generators/app_generator_test.rb

@@ -296,6 +296,16 @@ def test_app_update_preserves_skip_brakeman
     end
   end
 
+  def test_app_update_preserves_skip_rubocop
+    run_generator [ destination_root, "--skip-rubocop" ]
+
+    FileUtils.cd(destination_root) do
+      assert_no_changes -> { File.exist?("bin/rubocop") } do
+        run_app_update
+      end
+    end
+  end
+
   def test_app_update_preserves_skip_test
     run_generator [ destination_root, "--skip-test" ]