+ def test_Day_singularity(self) -> None:
+ """Test pointers made for single object keep pointing to it."""
+ day = Day('2024-01-01')
+ day.save(self.db_conn)
+ retrieved_day = Day.by_id(self.db_conn, '2024-01-01')
+ day.comment = 'foo'
+ self.assertEqual(retrieved_day.comment, 'foo')
+