@Test
public void testUseDelHint() {

  DatanodeStorageInfo delHint = new DatanodeStorageInfo(
      DFSTestUtil.getLocalDatanodeDescriptor(), new DatanodeStorage("id"));
  List<DatanodeStorageInfo> moreThan1Racks = Arrays.asList(delHint);
  List<StorageType> excessTypes = new ArrayList<>();
  BlockPlacementPolicyDefault policyDefault =
      (BlockPlacementPolicyDefault) bm.getBlockPlacementPolicy();
  excessTypes.add(StorageType.DEFAULT);
  Assert.assertTrue(policyDefault.useDelHint(delHint, null, moreThan1Racks,
      null, excessTypes));
  excessTypes.remove(0);
  excessTypes.add(StorageType.SSD);
  Assert.assertFalse(policyDefault.useDelHint(delHint, null, moreThan1Racks,
      null, excessTypes));
}