I prefer having it like below as there are about 10 quite dummy cases. In this way it is seen what is not allowed at once. Other tests have been rewritten. 

      expect(() => new Route("not-starting-with-slash/"),throwsFormatException);
      expect(() => new Route("/not-ending-with-slash"),  throwsFormatException);
      expect(() => new Route("/#some-chars-not-allowed"),throwsFormatException);
      expect(() => new Route("/{not_closed/"),           throwsFormatException);
      expect(() => new Route("/not_open}/"),             throwsFormatException);
      expect(() => new Route("/{{more-brackets}/"),      throwsFormatException);