/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/ is in ruby-shoulda-matchers 1.0.0~beta2-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/allow_mass_assignment_of_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/allow_value_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/association_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/ensure_inclusion_of_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/ensure_length_of_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/have_db_column_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/have_db_index_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/have_readonly_attribute_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/helpers.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/validate_acceptance_of_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/validate_format_of_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/validate_numericality_of_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/validate_presence_of_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/validate_uniqueness_of_matcher.rb
/usr/lib/ruby/vendor_ruby/shoulda/matchers/active_record/validation_matcher.rb