'Sentences with a bad checksum raise L{base.InvalidChecksum} when
attempting to validate them.'

def test_invalid(self):

    validate = nmea._validateChecksum
    (bareSentence, checksum) = GPGGA.split('*')
    badChecksum = intToBytes((int(checksum, 16) + 1))
    sentences = [((bareSentence + '*') + badChecksum)]
    for s in sentences:
        self.assertRaises(base.InvalidChecksum, validate, s)
