Snapshot(int id, String name, INodeDirectory dir) {
    this(id, dir, dir);
    this.root.setLocalName(DFSUtil.string2Bytes(name));
  }
@Test
  public void testSnapshot() throws Throwable {
    try {
      runTestSnapshot(SNAPSHOT_ITERATION_NUMBER);
    } catch(Throwable t) {
      SnapshotTestHelper.LOG.info("FAILED", t);
      SnapshotTestHelper.dumpTree("FAILED", cluster);
      throw t;
    }
  }