/usr/lib/ruby/ is in ruby-rails-dom-testing 1.0.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/rails/
/usr/lib/ruby/vendor_ruby/rails/dom/
/usr/lib/ruby/vendor_ruby/rails/dom/testing/
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions.rb
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions/
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions/tag_assertions.rb
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions/selector_assertions/
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions/selector_assertions/count_describable.rb
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions/selector_assertions/html_selector.rb
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions/selector_assertions/substitution_context.rb
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions/selector_assertions.rb
/usr/lib/ruby/vendor_ruby/rails/dom/testing/assertions/dom_assertions.rb
/usr/lib/ruby/vendor_ruby/rails/dom/testing/version.rb
/usr/lib/ruby/vendor_ruby/rails-dom-testing.rb