def test_joinFailure(self):
        """
        Test that an attempt to join an address which is not a multicast
        address fails with L{error.MulticastJoinError}.
        """
        # 127.0.0.1 is not a multicast address, so joining it should fail.
        return self.assertFailure(
            self.client.transport.joinGroup("127.0.0.1"),
            error.MulticastJoinError)

        Test that an attempt to join an address which is not a multicast
        address fails with L{error.MulticastJoinError}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_udp.py