def test_unjellyableFailure(self):
        """
        A non-jellyable L{pb.Error} subclass raised by a remote method is
        turned into a Failure with a type set to the FQPN of the exception
        type.
        """
        def failureUnjellyable(fail):
            self.assertEqual(
                fail.type,
                b'twisted.spread.test.test_pbfailure.SynchronousError')
            return 431
        return self._testImpl('synchronousError', 431, failureUnjellyable)

        A non-jellyable L{pb.Error} subclass raised by a remote method is
        turned into a Failure with a type set to the FQPN of the exception
        type.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/spread/test/test_pbfailure.py