def test_disorderlyShutdown(self):
        """
        If a L{TLSMemoryBIOProtocol} loses its connection unexpectedly, this is
        reported to the application.
        """
        clientConnectionLost = Deferred()
        clientFactory = ClientFactory()
        clientFactory.protocol = (
            lambda: ConnectionLostNotifyingProtocol(
                clientConnectionLost))

        clientContextFactory = HandshakeCallbackContextFactory()
        wrapperFactory = TLSMemoryBIOFactory(
            clientContextFactory, True, clientFactory)
        sslClientProtocol = wrapperFactory.buildProtocol(None)

        # Client speaks first, so the server can be dumb.
        serverProtocol = Protocol()

        loopbackAsync(serverProtocol, sslClientProtocol)

        # Now destroy the connection.
        serverProtocol.transport.loseConnection()

        # And when the connection completely dies, check the reason.
        def cbDisconnected(clientProtocol):
            clientProtocol.lostConnectionReason.trap(Error, ConnectionLost)
        clientConnectionLost.addCallback(cbDisconnected)
        return clientConnectionLost

        If a L{TLSMemoryBIOProtocol} loses its connection unexpectedly, this is
        reported to the application.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/protocols/test/test_tls.py