/** Test that FSNamesystem#clear clears all leases. */
  @Test
  public void testFSNamespaceClearLeases() throws Exception {
    Configuration conf = new HdfsConfiguration();
    File nameDir = new File(MiniDFSCluster.getBaseDirectory(), "name");
    conf.set(DFS_NAMENODE_NAME_DIR_KEY, nameDir.getAbsolutePath());

    NameNode.initMetrics(conf, NamenodeRole.NAMENODE);
    DFSTestUtil.formatNameNode(conf);
    FSNamesystem fsn = FSNamesystem.loadFromDisk(conf);
    LeaseManager leaseMan = fsn.getLeaseManager();
    leaseMan.addLease("client1", "importantFile");
    assertEquals(1, leaseMan.countLease());
    fsn.clear();
    leaseMan = fsn.getLeaseManager();
    assertEquals(0, leaseMan.countLease());
  }