/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/ is in ruby-rspec-expectations 3.4.0c3e0m1s1-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/all.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/base_matcher.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/be.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/be_between.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/be_instance_of.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/be_kind_of.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/be_within.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/change.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/compound.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/contain_exactly.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/cover.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/eq.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/eql.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/equal.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/exist.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/has.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/have_attributes.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/include.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/match.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/operators.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/output.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/raise_error.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/respond_to.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/satisfy.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/start_or_end_with.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/throw_symbol.rb
/usr/lib/ruby/vendor_ruby/rspec/matchers/built_in/yield.rb