def test_collapsingPumpPolicy(self):
        """
        L{collapsingPumpPolicy} is a pump policy which calls the target's
        C{dataReceived} only once with all of the strings in the queue passed
        to it joined together.
        """
        bytes = []
        client = Protocol()
        client.dataReceived = bytes.append
        queue = loopback._LoopbackQueue()
        queue.put(b"foo")
        queue.put(b"bar")
        queue.put(None)

        loopback.collapsingPumpPolicy(queue, client)

        self.assertEqual(bytes, [b"foobar"])

        L{collapsingPumpPolicy} is a pump policy which calls the target's
        C{dataReceived} only once with all of the strings in the queue passed
        to it joined together.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_loopback.py