def test_negative(self):
        """
        The given credentials are rejected by all the checkers.
        """
        for chk in self.getCheckers():
            for cred in self.getBadCredentials():
                d = chk.requestAvatarId(cred)
                yield self.assertFailure(d, error.UnauthorizedLogin)

        The given credentials are rejected by all the checkers.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/cred/test/test_cred.py