def test_printableCharacters(self):
        """
        When L{HistoricRecvLine} receives a printable character,
        it adds it to the current line buffer.
        """
        self.p.keystrokeReceived(b'x', None)
        self.p.keystrokeReceived(b'y', None)
        self.p.keystrokeReceived(b'z', None)

        self.assertEqual(self.p.currentLineBuffer(), (b'xyz', b''))

        When L{HistoricRecvLine} receives a printable character,
        it adds it to the current line buffer.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_recvline.py