def test_manually_specifying_parent_fk_single_subclass(self):
        related_name = 'manual_onetoone'
        child3 = InheritanceManagerTestChild3.objects.create()
        results = InheritanceManagerTestParent.objects.all().select_subclasses(related_name)

        expected_objs = [InheritanceManagerTestParent(pk=self.child1.pk),
                         InheritanceManagerTestParent(pk=self.child2.pk),
                         InheritanceManagerTestParent(pk=self.grandchild1.pk),
                         InheritanceManagerTestParent(pk=self.grandchild1_2.pk),
                         child3]
        self.assertEqual(list(results), expected_objs)
        expected_related_names = [related_name]
        self.assertEqual(set(results.subclasses),
                         set(expected_related_names))
Using a string related_name when the relation is manually defined
dataset/ETHPy150Open carljm/django-model-utils/model_utils/tests/tests.py/InheritanceManagerTests.test_manually_specifying_parent_fk_single_subclass