def METHOD_NAME(base):
    """Test _MockEstimatorMixin is valid for all sktime estimator base classes."""
    class _DummyClass(base, _MockEstimatorMixin):
        def __init__(self):
            super().__init__()
        def _fit(self):
            """Empty method, here for testing purposes."""
            pass
        def _predict(self):
            """Empty method, here for testing purposes."""
            pass
        def _score(self):
            """Empty method, here for testing purposes."""
            pass
    dummy_instance = _DummyClass()
    assert hasattr(dummy_instance, "log")
    dummy_instance.add_log_item(42)
    assert hasattr(dummy_instance, "_MockEstimatorMixin__log")