# File lib/email_spec/matchers.rb, line 259
      def failure_message_when_negated
        if @expected_subject.is_a?(String)
          "expected no email with the subject #{@expected_subject.inspect} but found at least one. Subjects were #{@given_emails.map(&:subject).inspect}"
        else
          "expected no email to have a subject matching #{@expected_subject.inspect} but found at least one. Subjects were #{@given_emails.map(&:subject).inspect}"
        end
      end