def test_buildProtocol(self):
        """
        By default, buildProtocol() constructs an instance of
        SSHServerTransport.
        """
        factory = self.makeSSHFactory()
        protocol = factory.buildProtocol(None)
        self.assertIsInstance(protocol, transport.SSHServerTransport)

        By default, buildProtocol() constructs an instance of
        SSHServerTransport.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_ssh.py