@Override
      public String explainFailure() throws Exception {
        return "Still have some hfiles in the archive, when their snapshot has been deleted: "
          + getHFiles(archiveDir, fs, TABLE_NAME);
      }
Test that the snapshot hfile archive cleaner works correctly. HFiles that are in snapshots
should be retained, while those that are not in a snapshot should be deleted.
@throws Exception on failure
hbase-server/src/test/java/org/apache/hadoop/hbase/master/cleaner/TestSnapshotFromMaster.java