Unusual Unittest behavior

#!/opt/local/bin/python

import copy
import unittest
import types
import exceptions


KIM1_RECORD_BEGIN = ";"
RECORD_CHECKSUM_LENGTH = 4    # of characters
RECORD_IDENTIFIER_LENGTH = 1  # of characters
RECORD_BYTE_LENGTH = 2        # of characters
RECORD_ADDRESS_LENGTH = 4     # of characters
RECORD_DATA_LENGTH = 48       # of characters

ACTUAL_CHECKSUM_OFFSET = -4

EXPECTED_RECORD_LENGTH = RECORD_IDENTIFIER_LENGTH + RECORD_BYTE_LENGTH + RECORD_ADDRESS_LENGTH + RECORD_DATA_LENGTH + RECORD_CHECKSUM_LENGTH


class RecordIntegrityError(exceptions.Exception):

    def __init__(self, args):
        exceptions.Exception.__init__(self)
        print type(args)
        self.args=args

    def __str__(self):
        return "".join(self.args)

class ChecksumValidationError(exceptions.Exception):

    def __init__(self, args):
        exceptions.Exception.__init__(self)
        self.args=args

    def __str__(self):
        return "".join(self.args)

def checksum(record):

    if not record.startswith(KIM1_RECORD_BEGIN):
        raise RecordIntegrityError("\nInvalid Record: does not begin with -> %s" % KIM1_RECORD_BEGIN)

    if type(record) is not types.StringType:
        raise RecordIntegrityError("\nRecord data type must be StringType")

    actualRecordLength = len(record)
    if actualRecordLength != EXPECTED_RECORD_LENGTH:
        raise RecordIntegrityError("\nExpected record length: %lu bytes, Actual Record Length: %lu bytes," % (EXPECTED_RECORD_LENGTH, actualRecordLength))

    rawRecord = copy.deepcopy(record)
    expectedChecksum = int(rawRecord[ACTUAL_CHECKSUM_OFFSET:],16) & 0xFFFF
    workingRecord = iter(rawRecord[1:ACTUAL_CHECKSUM_OFFSET])

    calculatedChecksum = 0

    for byte in workingRecord:

        temp = []
        temp.append(byte)
        temp.append(workingRecord.next())

        calculatedChecksum += int("".join(temp),16) & 0xFFFF

    return expectedChecksum, calculatedChecksum


class ChecksumValidaterPUT(unittest.TestCase):

    def setUp(self):

        self.record1 = ";180000FFEEDDCCBBAA0099887766554433221122334455667788990AFC"
        self.record2 = ";180218778E4017203C02A20C8E4217A2318E4017203C02A20E8E420717"
        self.record3 = ";180230EA65ED65EE85E9A204B5E995EACA10F938E999B0E8A5EB290FE8"
        #record4 = ";1800000204A900A885FA8570A2028672A50085FBA601A57049FF850B2D"
        #record5 = ";1800187191FAC8D0FBE6FBE4FBB0F5A672A50085FBA570CA1004A20FF6"
        #record6 = ";1800300291FAC8D0F6E6FBA501C5FBB0ECA50085FBA672A571CA100F73"
        #record7 = ";18004804A202A570D1FAD015C8D0F0E6FBA501C5FBB0E8C67210AD0F29"
        #record8 = ";180060A57049FF30A184FA4C4F1C0000000000CE1ECE1ECE9E7E5E09FB"

        self.testRecords = (self.record1, self.record2, self.record3)

    def test_checksumvalidater(self):

        for recnum, record in enumerate(self.testRecords,start=1):

            print"\nRecord # %2lu, %s" % (recnum,record),
            expectedChecksum, calculatedChecksum = checksum(record)
            self.assertEqual(expectedChecksum,calculatedChecksum)
            recnum +=1


if __name__ == '__main__':

    unittest.main()




Record #  1, ;180000FFEEDDCCBBAA0099887766554433221122334455667788990AFC
Record #  2, ;180218778E4017203C02A20C8E4217A2318E4017203C02A20E8E420717
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK
Record #  3, ;180230EA65ED65EE85E9A204B5E995EACA10F938E999B0E8A5EB290FE8