with require 'active_support/concern' list.

gistfile1.txt

./actionpack/lib/action_view/helpers/asset_tag_helpers/javascript_tag_helpers.rb
./actionpack/lib/action_view/helpers/asset_tag_helpers/stylesheet_tag_helpers.rb
./activemodel/lib/active_model/conversion.rb
./railties/lib/rails/railtie/configurable.rb
./activerecord/lib/active_record/readonly_attributes.rb
./activerecord/lib/active_record/core.rb
./activerecord/lib/active_record/persistence.rb
./activerecord/lib/active_record/inheritance.rb
./activerecord/lib/active_record/attribute_assignment.rb
./activerecord/lib/active_record/sanitization.rb
./activerecord/lib/active_record/scoping.rb
./activerecord/lib/active_record/scoping/default.rb
./activerecord/lib/active_record/store.rb
./activerecord/lib/active_record/model_schema.rb
./activerecord/lib/active_record/model.rb
./activesupport/test/concern_test.rb
./activesupport/lib/active_support/configurable.rb
./activesupport/lib/active_support/concern.rb
./activesupport/lib/active_support/testing/performance.rb
./activesupport/lib/active_support/testing/setup_and_teardown.rb