def test_transfer(self):
        """
        An attempt is made to transfer the zone for the domain the
        L{SecondaryAuthority} was constructed with from the server address it
        was constructed with when L{SecondaryAuthority.transfer} is called.
        """
        secondary = SecondaryAuthority.fromServerAddressAndDomain(
            ('192.168.1.2', 1234), 'example.com')
        secondary._reactor = reactor = MemoryReactorClock()

        secondary.transfer()

        # Verify a connection attempt to the server address above
        host, port, factory, timeout, bindAddress = reactor.tcpClients.pop(0)
        self.assertEqual(host, '192.168.1.2')
        self.assertEqual(port, 1234)

        # See if a zone transfer query is issued.
        proto = factory.buildProtocol((host, port))
        transport = StringTransport()
        proto.makeConnection(transport)

        msg = Message()
        # DNSProtocol.writeMessage length encodes the message by prepending a
        # 2 byte message length to the buffered value.
        msg.decode(BytesIO(transport.value()[2:]))

        self.assertEqual(
            [dns.Query('example.com', dns.AXFR, dns.IN)], msg.queries)

        An attempt is made to transfer the zone for the domain the
        L{SecondaryAuthority} was constructed with from the server address it
        was constructed with when L{SecondaryAuthority.transfer} is called.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_names.py