testcase.py

    def test_get_fields_only_searaches_forward_on_apps_not_ready(self):
        opts = Person._meta

        # If apps registry is not ready, get_field() searches
        # over only forward fields.
        opts.apps.ready = False

        # 'data_abstract' is a forward field, and therefore will be found
        self.assertTrue(opts.get_field('data_abstract'))

        message = "Person has no field named 'relating_baseperson'. The app cache " \
                  "isn't ready yet, so if this is a forward field, it won't be " \
                  "available yet."

        with self.assertRaises(FieldDoesNotExist) as err:
            opts.get_field('relating_baseperson')
        self.assertEqual(str(err.exception), message)

        opts.apps.ready = True