def test_securityFailure(self):
        """
        Test that even if an exception is not explicitly jellyable (by being
        a L{pb.Jellyable} subclass), as long as it is an L{pb.Error}
        subclass it receives the same special treatment.
        """
        def failureSecurity(fail):
            fail.trap(SecurityError)
            self.assertNotIsInstance(fail.type, str)
            self.assertIsInstance(fail.value, fail.type)
            return 4300
        return self._testImpl('security', 4300, failureSecurity)

        Test that even if an exception is not explicitly jellyable (by being
        a L{pb.Jellyable} subclass), as long as it is an L{pb.Error}
        subclass it receives the same special treatment.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/spread/test/test_pbfailure.py