def test_ednsMessageDecodeMultipleOptRecords(self):
        """
        An L(_EDNSMessage} instance created from a byte string containing
        multiple I{OPT} records will discard all the C{OPT} records.

        C{ednsVersion} will be set to L{None}.

        @see: U{https://tools.ietf.org/html/rfc6891#section-6.1.1}
        """
        m = dns.Message()
        m.additional = [
            dns._OPTHeader(version=2),
            dns._OPTHeader(version=3)]

        ednsMessage = dns._EDNSMessage()
        ednsMessage.fromStr(m.toStr())

        self.assertIsNone(ednsMessage.ednsVersion)

        An L(_EDNSMessage} instance created from a byte string containing
        multiple I{OPT} records will discard all the C{OPT} records.

        C{ednsVersion} will be set to L{None}.

        @see: U{https://tools.ietf.org/html/rfc6891#section-6.1.1}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_dns.py