def testFullDuplexCallCancelled(self):
        self._protoc()

        with _CreateService(self._payload_pb2, self._responses_pb2,
                            self._service_pb2) as (methods, stub):
            request_iterator = _full_duplex_request_iterator(self._requests_pb2)
            responses = stub.FullDuplexCall(request_iterator,
                                            test_constants.LONG_TIMEOUT)
            next(responses)
            responses.cancel()
            with self.assertRaises(face.CancellationError):
                next(responses)