def test_sendPacketPlain(self):
        """
        Test that plain (unencrypted, uncompressed) packets are sent
        correctly.  The format is::
            uint32 length (including type and padding length)
            byte padding length
            byte type
            bytes[length-padding length-2] data
            bytes[padding length] padding
        """
        proto = MockTransportBase()
        proto.makeConnection(self.transport)
        self.finishKeyExchange(proto)
        self.transport.clear()
        message = ord('A')
        payload = b'BCDEFG'
        proto.sendPacket(message, payload)
        value = self.transport.value()
        self.assertEqual(value, b'\x00\x00\x00\x0c\x04ABCDEFG\x99\x99\x99\x99')

        Test that plain (unencrypted, uncompressed) packets are sent
        correctly.  The format is::
            uint32 length (including type and padding length)
            byte padding length
            byte type
            bytes[length-padding length-2] data
            bytes[padding length] padding
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_transport.py