def test_data(self):
        """
        Test specific behavior of the 16-bits length.
        """
        r = self.getProtocol()
        r.sendString(b"foo")
        self.assertEqual(r.transport.value(), b"\x00\x03foo")
        r.dataReceived(b"\x00\x04ubar")
        self.assertEqual(r.received, [b"ubar"])

        Test specific behavior of the 16-bits length.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/protocols/test/test_basic.py