@Test(timeout = TIMEOUT)
public void a_new_callback_can_be_set_after_workers_are_finished() {

    WorkerCounter counter = new WorkerCounter(realExecutor);
    counter.afterPreviousWorkersFinished(log("callback 1"));
    counter.afterPreviousWorkersFinished(log("callback 2"));
    events.assertContains("callback 1", "callback 2");
}