def test_repr(self):
        """
        L{dns._OPTHeader.__repr__} displays the name and type and all
        the fixed and extended header values of the OPT record.
        """
        self.assertEqual(
            repr(dns._OPTHeader()),
            '<_OPTHeader '
            'name= '
            'type=41 '
            'udpPayloadSize=4096 '
            'extendedRCODE=0 '
            'version=0 '
            'dnssecOK=False '
            'options=[]>')

        L{dns._OPTHeader.__repr__} displays the name and type and all
        the fixed and extended header values of the OPT record.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_dns.py