def test_alternate_finders(self):

        class Unknown(object):
            pass

        class Known(MyBaseClass):
            pass

        register_class(Known)
        k, u = Known(), Unknown()

        assert instrumentation.manager_of_class(Unknown) is None
        assert instrumentation.manager_of_class(Known) is not None
        assert instrumentation.manager_of_class(None) is None

        assert attributes.instance_state(k) is not None
        assert_raises((AttributeError, KeyError),
                      attributes.instance_state, u)
        assert_raises((AttributeError, KeyError),
                      attributes.instance_state, None)
Ensure the generic finder front-end deals with edge cases.
dataset/ETHPy150Open zzzeek/sqlalchemy/test/ext/test_extendedattr.py/UserDefinedExtensionTest.test_alternate_finders