'Unregistering a streaming producer when no producer is registered is
safe.'

def test_streamingProducerUnregisterTwice(self):

    (clientProtocol, tlsProtocol, producer) = self.setupStreamingProducer()
    clientProtocol.transport.unregisterProducer()
    clientProtocol.transport.unregisterProducer()
    self.assertIsNone(tlsProtocol._producer)
    self.assertIsNone(tlsProtocol.transport.producer)
