def test_negative_with_unexpected_instance_attr(self):
    ' Test if the target class has already had an attribute `_singleton_instance` but it is not compatible. '
    try:

        @singleton
        class SuperDummyClass(TestDecoratorCommonSingletonClass.DummyTest):
            _singleton_instance = {}

            def __init__(self):
                super(self.__class__, self).__init__()
        self.assertTrue(False, 'Singleton Class: Passed the initialization unexpectedly.')
    except SingletonInitializationException:
        self.assertTrue(True, 'Singleton Class: Failed the initialization with expected exception.')
Test if the target class has already had an attribute `_singleton_instance` but it is not compatible.
def test_negative_with_unexpected_instance_attr(self):
    '  '
    try:

        @singleton
        class SuperDummyClass(TestDecoratorCommonSingletonClass.DummyTest):
            _singleton_instance = {}

            def __init__(self):
                super(self.__class__, self).__init__()
        self.assertTrue(False, 'Singleton Class: Passed the initialization unexpectedly.')
    except SingletonInitializationException:
        self.assertTrue(True, 'Singleton Class: Failed the initialization with expected exception.')