@no_oracle
    def test13_select_related_null_fk(self):
        Book.objects.create(title='Without Author')
        b = Book.objects.select_related('author').get(title='Without Author')
        # Should be `None`, and not a 'dummy' model.
        self.assertIsNone(b.author)
Testing `select_related` on a nullable ForeignKey.
dataset/ETHPy150Open django/django/tests/gis_tests/relatedapp/tests.py/RelatedGeoModelTest.test13_select_related_null_fk