def test_concrete_abstract_concrete_pk(self):
        # Regression test for #13987: Primary key is incorrectly determined
        # when more than one model has a concrete->abstract->concrete
        # inheritance hierarchy.
        self.assertEqual(
            len([field for field in BusStation._meta.local_fields
                       if field.primary_key]),
            1
        )
        self.assertEqual(
            len([field for field in TrainStation._meta.local_fields
                       if field.primary_key]),
            1
        )
        self.assertIs(BusStation._meta.pk.model, BusStation)
        self.assertIs(TrainStation._meta.pk.model, TrainStation)
Primary key set correctly with concrete->abstract->concrete inheritance.
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.4/tests/regressiontests/model_inheritance_regress/tests.py/ModelInheritanceTest.test_concrete_abstract_concrete_pk