def test_badContext(self):
        """
        If the context factory passed to L{ITCPTransport.startTLS} raises an
        exception from its C{getContext} method, that exception is raised by
        L{ITCPTransport.startTLS}.
        """
        reactor = self.buildReactor()

        brokenFactory = BrokenContextFactory()
        results = []

        serverFactory = ServerFactory.forProtocol(Protocol)
        port = reactor.listenTCP(0, serverFactory, interface=self.interface)
        endpoint = self.endpoints.client(reactor, port.getHost())

        clientFactory = ClientFactory()
        clientFactory.protocol = Protocol
        connectDeferred = endpoint.connect(clientFactory)

        def connected(protocol):
            if not ITLSTransport.providedBy(protocol.transport):
                results.append("skip")
            else:
                results.append(self.assertRaises(ValueError,
                                                 protocol.transport.startTLS,
                                                 brokenFactory))

        def connectFailed(failure):
            results.append(failure)

        def whenRun():
            connectDeferred.addCallback(connected)
            connectDeferred.addErrback(connectFailed)
            connectDeferred.addBoth(lambda ign: reactor.stop())
        needsRunningReactor(reactor, whenRun)

        self.runReactor(reactor)

        self.assertEqual(len(results), 1,
                         "more than one callback result: %s" % (results,))

        if isinstance(results[0], Failure):
            # self.fail(Failure)
            results[0].raiseException()
        if results[0] == "skip":
            raise SkipTest("Reactor does not support ITLSTransport")
        self.assertEqual(BrokenContextFactory.message, str(results[0]))

        If the context factory passed to L{ITCPTransport.startTLS} raises an
        exception from its C{getContext} method, that exception is raised by
        L{ITCPTransport.startTLS}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_tcp.py