# File lib/action_mailer/test_case.rb, line 25
        def tests(mailer)
          case mailer
          when String, Symbol
            self._mailer_class = mailer.to_s.camelize.constantize
          when Module
            self._mailer_class = mailer
          else
            raise NonInferrableMailerError.new(mailer)
          end
        end