def test_serverRepr(self):
        """
        Check that the repr string of the server transport get the good port
        number if the server listens on 0.
        """
        server = MyServerFactory()
        serverConnMade = server.protocolConnectionMade = defer.Deferred()
        port = reactor.listenTCP(0, server)
        self.addCleanup(port.stopListening)

        client = MyClientFactory()
        clientConnMade = client.protocolConnectionMade = defer.Deferred()
        connector = reactor.connectTCP("127.0.0.1",
                                       port.getHost().port, client)
        self.addCleanup(connector.disconnect)
        def check(result):
            serverProto, clientProto = result
            portNumber = port.getHost().port
            self.assertEqual(
                repr(serverProto.transport),
                "<AccumulatingProtocol #0 on %s>" % (portNumber,))
            serverProto.transport.loseConnection()
            clientProto.transport.loseConnection()
        return defer.gatherResults([serverConnMade, clientConnMade]
            ).addCallback(check)

        Check that the repr string of the server transport get the good port
        number if the server listens on 0.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_tcp.py