@Test
  public void removeWorkerTest() {
    mInfo.addWorker(1, "MEM");
    Assert.assertTrue(mInfo.getWorkers().contains(1L));
    mInfo.removeWorker(1);
    Assert.assertEquals(0, mInfo.getWorkers().size());

    // remove nonexiting worker.
    mInfo.removeWorker(1);
    Assert.assertEquals(0, mInfo.getWorkers().size());
  }