def test_check_db_fails(self):
        with self.assertRaisesRegex(ValueError, 'no database'):
            dbcore.Model()._check_db()
        with self.assertRaisesRegex(ValueError, 'no id'):
            ModelFixture1(self.db)._check_db()

        dbcore.Model(self.db)._check_db(need_id=False)