def METHOD_NAME(self) -> None:
    """Test that the background update to populate the rooms creator column
    works properly.
    """
    # Insert a room without the creator
    room_id = self._generate_room()
    self.get_success(
        self.store.db_pool.simple_update(
            table="rooms",
            keyvalues={"room_id": room_id},
            updatevalues={"creator": None},
            desc="test",
        )
    )
    # Make sure the test is starting out with a room without a creator
    room_creator_before = self.get_success(
        self.store.db_pool.simple_select_one_onecol(
            table="rooms",
            keyvalues={"room_id": room_id},
            retcol="creator",
            allow_none=True,
        )
    )
    self.assertEqual(room_creator_before, None)
    self.run_background_updates(_BackgroundUpdates.POPULATE_ROOMS_CREATOR_COLUMN)
    # Make sure the background update filled in the room creator
    room_creator_after = self.get_success(
        self.store.db_pool.simple_select_one_onecol(
            table="rooms",
            keyvalues={"room_id": room_id},
            retcol="creator",
            allow_none=True,
        )
    )
    self.assertEqual(room_creator_after, self.user_id)