### Question:
Upgrader9to10 implements Upgrader { public static String upgradeDirColumn(String dir) { return new Path(dir).getName(); }  @Override void upgradeZookeeper(ServerContext ctx); @Override void upgradeRoot(ServerContext ctx); @Override void upgradeMetadata(ServerContext ctx); void upgradeFileDeletes(ServerContext ctx, Ample.DataLevel level); void upgradeDirColumns(ServerContext ctx, Ample.DataLevel level); static String upgradeDirColumn(String dir); static void upgradeRelativePaths(ServerContext ctx, Ample.DataLevel level); static void replaceRelativePaths(AccumuloClient c, VolumeManager fs, String tableName,
      String upgradeProperty); static boolean checkForRelativePaths(AccumuloClient client, VolumeManager fs,
      String tableName, String upgradeProperty); static final String ZROOT_TABLET_LOCATION; static final String ZROOT_TABLET_FUTURE_LOCATION; static final String ZROOT_TABLET_LAST_LOCATION; static final String ZROOT_TABLET_WALOGS; static final String ZROOT_TABLET_CURRENT_LOGS; static final String ZROOT_TABLET_PATH; static final Value UPGRADED; static final String OLD_DELETE_PREFIX; static final long CANDIDATE_BATCH_SIZE; }### Answer:
@Test public void testUpgradeDir() { assertEquals("t-0005", Upgrader9to10.upgradeDirColumn("hdfs: assertEquals("t-0005", Upgrader9to10.upgradeDirColumn("../5a/t-0005")); assertEquals("t-0005", Upgrader9to10.upgradeDirColumn("/t-0005")); assertEquals("t-0005", Upgrader9to10.upgradeDirColumn("t-0005")); }