@Override
      public Boolean answer(InvocationOnMock invocation) throws Throwable {
        fs.create(addedFile).close();
        CommonFSUtils.logFileSystemState(fs, testDir, LOG);
        return (Boolean) invocation.callRealMethod();
      }
While cleaning a directory, all the files in the directory may be deleted, but there may be
another file added, in which case the directory shouldn't be deleted.
@throws IOException on failure
hbase-server/src/test/java/org/apache/hadoop/hbase/master/cleaner/TestCleanerChore.java