@After
  public void tearDown() throws Exception {
    EnvironmentEdgeManagerTestHelper.reset();
    if (region != null) {
      HBaseTestingUtil.closeRegionAndWAL(region);
    }
  }
Test the {@link MemStoreCompactorSegmentsIterator} and {@link MemStoreMergerSegmentsIterator}
class, Test for bug : HBASE-22324
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestMemStoreSegmentsIterator.java