def test_getPacketPlain(self):
        """
        Test that packets are retrieved correctly out of the buffer when
        no encryption is enabled.
        """
        proto = MockTransportBase()
        proto.makeConnection(self.transport)
        self.finishKeyExchange(proto)
        self.transport.clear()
        proto.sendPacket(ord('A'), b'BC')
        proto.buf = self.transport.value() + b'extra'
        self.assertEqual(proto.getPacket(), b'ABC')
        self.assertEqual(proto.buf, b'extra')

        Test that packets are retrieved correctly out of the buffer when
        no encryption is enabled.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_transport.py