def test_Charstr(self):
        """
        Test L{dns.Charstr} encode and decode.
        """
        for n in self.names:
            # encode the name
            f = BytesIO()
            dns.Charstr(n).encode(f)

            # decode the name
            f.seek(0, 0)
            result = dns.Charstr()
            result.decode(f)
            self.assertEqual(result.string, n)

        Test L{dns.Charstr} encode and decode.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_dns.py