/usr/lib/ruby/vendor_ruby/ is in ruby-rspec-expectations 2.5.0-2ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/rspec-expectations.rb
/usr/lib/ruby/vendor_ruby/rspec/
/usr/lib/ruby/vendor_ruby/rspec/expectations/
/usr/lib/ruby/vendor_ruby/rspec/expectations/handler.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/backward_compatibility.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/extensions/
/usr/lib/ruby/vendor_ruby/rspec/expectations/extensions/kernel.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/extensions/array.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/errors.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/differ.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/extensions.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/deprecation.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/version.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/match_array.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations/fail_with.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers.rb
/usr/lib/ruby/vendor_ruby/rspec/expectations.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/
/usr/lib/ruby/vendor_ruby/rspec/matchers/pretty.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/respond_to.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/dsl.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/has.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/match.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/include.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/extensions/
/usr/lib/ruby/vendor_ruby/rspec/matchers/extensions/instance_exec.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/errors.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/change.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/exist.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/matcher.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/be_within.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/equal.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/be_instance_of.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/throw_symbol.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/satisfy.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/method_missing.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/generated_descriptions.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/eql.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/have.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/compatibility.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/eq.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/raise_error.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/operator_matcher.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/be_kind_of.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/block_aliases.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/be_close.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/be.rb