Pyhton TestCase运行闪退与失败，原因不详。。。

把源码贴上来，希望某位大神可以指点迷津：

"""Unit test for odbchelper.py

This program is part of "Dive Into Python", a free Python book for
experienced programmers. Visit http://diveintopython.org/ for the
latest version.
"""

__author__ = "Mark Pilgrim (mark@diveintopython.org)"
__version__ = "$Revision: 1.2 $"
__date__ = "$Date: 2004/05/05 21:57:19 $"
__copyright__ = "Copyright (c) 2001 Mark Pilgrim"
__license__ = "Python"

import unittest
import odbchelper

class GoodInput(unittest.TestCase):
def testBlank(self):
"""buildConnectionString handles empty dictionary"""
self.assertEqual("", odbchelper.buildConnectionString({}))
def testKnownValue(self):
"""buildConnectionString returns known result with known input"""
params = {"server":"mpilgrim", "database":"master", "uid":"sa", "pwd":"secret"}
knownItems = params.items()
knownItems.sort()
knownString = repr(knownItems)
result = odbchelper.buildConnectionString(params)
resultItems = [tuple(e.split("=")) for e in result.split(";")]
resultItems.sort()
resultString = repr(resultItems)
self.assertEqual(knownString, resultString)

class BadInput(unittest.TestCase):
def testString(self):
"""buildConnectionString should fail with string input"""
self.assertRaises(AttributeError, odbchelper.buildConnectionString, "")

def testList(self):
"""buildConnectionString should fail with list input"""
self.assertRaises(AttributeError, odbchelper.buildConnectionString, [])

def testTuple(self):
"""buildConnectionString should fail with tuple input"""
self.assertRaises(AttributeError, odbchelper.buildConnectionString, ())

if __name__ == "__main__":
unittest.main()