def test_invalidIdListParserNonPositive(self):
        """
        Zeroes and negative values are not accepted in id range expressions. RFC
        3501 states that sequence numbers and sequence ranges consist of
        non-negative numbers (RFC 3501 section 9, the seq-number grammar item).
        """
        inputs = [
            b'0:5',
            b'0:0',
            b'*:0',
            b'0',
            b'-3:5',
            b'1:-2',
            b'-1'
        ]

        for input in inputs:
            self.assertRaises(imap4.IllegalIdentifierError,
                              imap4.parseIdList, input, 12345)

        Zeroes and negative values are not accepted in id range expressions. RFC
        3501 states that sequence numbers and sequence ranges consist of
        non-negative numbers (RFC 3501 section 9, the seq-number grammar item).
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_imap.py