@Test
  public void getBlockLocationsTest() {
    mInfo.addWorker(3, "HDD");
    mInfo.addWorker(1, "MEM");
    mInfo.addWorker(2, "MEM");

    List<MasterBlockLocation> locations = mInfo.getBlockLocations();
    Assert.assertEquals(3, mInfo.getNumLocations());
    // mem in the top of the list
    Assert.assertEquals(1, locations.get(0).getWorkerId());
    Assert.assertEquals(2, locations.get(1).getWorkerId());
    Assert.assertEquals(3, locations.get(2).getWorkerId());
  }