class Shoulda::Matchers::ActiveRecord::AssociationMatchers::OptionalMatcher

def build_missing_option
  String.new('and for the record ').tap do |missing_option_string|
    missing_option_string <<
      if optional
        'not to '
      else
        'to '
      end
    missing_option_string << (
      'fail validation if '\
      ":#{attribute_name} is unset; i.e., either the association "\
      'should have been defined with `optional: '\
      "#{optional.inspect}`, or there "
    )
    missing_option_string <<
      if optional
        'should not '
      else
        'should '
      end
    missing_option_string << "be a presence validation on :#{attribute_name}"
  end
end