Как создать набор тестов в python unittest

Я пробовал:

def buildTestSuite():
    suite = unittest.TestSuite()
    for testcase in glob.glob('src/testsuite/test_*.py'):
        module = os.path.splitext(testcase)[0]
        print module
        print type(module)
        suite.addTest(__import__(module).buildTestSuite())
    return suite

, но получаю ошибку:

Traceback (most recent call last):
  File "runtests.py", line 63, in ?
    results = main()
  File "runtests.py", line 57, in main
    results = unittest.TextTestRunner().run(buildTestSuite())
  File "runtests.py", line 53, in buildTestSuite
    suite.addTest(__import__(module).buildTestSuite())
AttributeError: 'module' object has no attribute 'buildTestSuite'