### Question:
RootTabletLocator extends TabletLocator { @Override public void invalidateCache(KeyExtent failedExtent) {} RootTabletLocator(TabletServerLockChecker lockChecker); @Override void binMutations(ClientContext context, List<T> mutations,
      Map<String,TabletServerMutations<T>> binnedMutations, List<T> failures); @Override List<Range> binRanges(ClientContext context, List<Range> ranges,
      Map<String,Map<KeyExtent,List<Range>>> binnedRanges); @Override void invalidateCache(KeyExtent failedExtent); @Override void invalidateCache(Collection<KeyExtent> keySet); @Override void invalidateCache(ClientContext context, String server); @Override void invalidateCache(); @Override TabletLocation locateTablet(ClientContext context, Text row, boolean skipRow,
      boolean retry);  }### Answer:
@Test public void testInvalidateCache_Server() { zc.clear(context.getZooKeeperRoot() + Constants.ZTSERVERS + "/server"); replay(zc); rtl.invalidateCache(context, "server"); verify(zc); }