AttributeError: 'bool' object has no attribute '_formatMessage'

cls =

@classmethod
def setUpClass(cls):
    SMALL_TEST_DATA_URI = os.environ.get('SMALL_TEST_DATA_URI', None)
    SMALL_TEST_DATA_LEGACY_URI = os.environ.get('SMALL_TEST_DATA_LEGACY_URI', None)

    if SMALL_TEST_DATA_URI is None or SMALL_TEST_DATA_LEGACY_URI is None:
        for i in range(10):
            print("TEST DATA NOT SET UP")
            print("SMALL_TEST_DATA_URI OR SMALL_TEST_DATA_LEGACY_URI ENVIRONMENT VARIABLES NOT SET")
            print("YOUR TEST CONFIGURATION IS PROBABLY BROKEN, THE TESTS ARE PROBABLY OK")
            print("!!!!!!!!!!!!!!!!!!!!!!! +++++++++  READ THE README FILE  ++++++++ !!!!!!!!!!!!!!!!!!!!!!!!")

      cls.assertTrue(False,expr=None)

E AttributeError: 'bool' object has no attribute '_formatMessage'