def METHOD_NAME(self, frozen_time):
    """If workers don't check in for a long enough time period, they should be removed."""
    self.mock_worker_checkin(cpus=1, user_id=self.user_id)
    self.assertEqual(len(self.bundle_manager._worker_model.get_workers()), 1)
    frozen_time.move_to("2020-02-12")
    self.bundle_manager._schedule_run_bundles()
    self.assertEqual(len(self.bundle_manager._worker_model.get_workers()), 0)