@Test
public void testInitializeBlockRecovery() throws Exception {

  DatanodeStorageInfo s1 = DFSTestUtil.createDatanodeStorageInfo("10.10.1.1", "s1");
  DatanodeDescriptor dd1 = s1.getDatanodeDescriptor();
  DatanodeStorageInfo s2 = DFSTestUtil.createDatanodeStorageInfo("10.10.1.2", "s2");
  DatanodeDescriptor dd2 = s2.getDatanodeDescriptor();
  DatanodeStorageInfo s3 = DFSTestUtil.createDatanodeStorageInfo("10.10.1.3", "s3");
  DatanodeDescriptor dd3 = s3.getDatanodeDescriptor();
  dd1.setAlive(true);
  dd2.setAlive(true);
  dd3.setAlive(true);
  BlockInfoContiguous blockInfo = new BlockInfoContiguous(
      new Block(0, 0, GenerationStamp.LAST_RESERVED_STAMP), (short) 3);
  blockInfo.convertToBlockUnderConstruction(BlockUCState.UNDER_CONSTRUCTION,
      new DatanodeStorageInfo[] {s1, s2, s3});
  // Recovery attempt #1.
  DFSTestUtil.resetLastUpdatesWithOffset(dd1, -3 * 1000);
  DFSTestUtil.resetLastUpdatesWithOffset(dd2, -1 * 1000);
  DFSTestUtil.resetLastUpdatesWithOffset(dd3, -2 * 1000);
  blockInfo.getUnderConstructionFeature().initializeBlockRecovery(blockInfo, 1, true);
  BlockInfo[] blockInfoRecovery = dd2.getLeaseRecoveryCommand(1);
  assertEquals(blockInfoRecovery[0], blockInfo);
  // Recovery attempt #2.
  DFSTestUtil.resetLastUpdatesWithOffset(dd1, -2 * 1000);
  DFSTestUtil.resetLastUpdatesWithOffset(dd2, -1 * 1000);
  DFSTestUtil.resetLastUpdatesWithOffset(dd3, -3 * 1000);
  blockInfo.getUnderConstructionFeature().initializeBlockRecovery(blockInfo, 2, true);
  blockInfoRecovery = dd1.getLeaseRecoveryCommand(1);
  assertEquals(blockInfoRecovery[0], blockInfo);
  // Recovery attempt #3.
  DFSTestUtil.resetLastUpdatesWithOffset(dd1, -2 * 1000);
  DFSTestUtil.resetLastUpdatesWithOffset(dd2, -1 * 1000);
  DFSTestUtil.resetLastUpdatesWithOffset(dd3, -3 * 1000);
  blockInfo.getUnderConstructionFeature().initializeBlockRecovery(blockInfo, 3, true);
  blockInfoRecovery = dd3.getLeaseRecoveryCommand(1);
  assertEquals(blockInfoRecovery[0], blockInfo);
  // Recovery attempt #4.
  // Reset everything. And again pick DN with most recent heart beat.
  DFSTestUtil.resetLastUpdatesWithOffset(dd1, -2 * 1000);
  DFSTestUtil.resetLastUpdatesWithOffset(dd2, -1 * 1000);
  DFSTestUtil.resetLastUpdatesWithOffset(dd3, 0);
  blockInfo.getUnderConstructionFeature().initializeBlockRecovery(blockInfo, 3, true);
  blockInfoRecovery = dd3.getLeaseRecoveryCommand(1);
  assertEquals(blockInfoRecovery[0], blockInfo);
}