@Override
  public void preDelete(final ObserverContext<? extends RegionCoprocessorEnvironment> c,
    final Delete delete, final WALEdit edit, final Durability durability) throws IOException {
    Map<byte[], List<Cell>> familyMap = delete.getFamilyCellMap();
    RegionCoprocessorEnvironment e = c.getEnvironment();
    assertNotNull(e);
    assertNotNull(e.getRegion());
    assertNotNull(familyMap);
    if (ctBeforeDelete.get() > 0) {
      ctPreDeleted.incrementAndGet();
    }
  }
A sample region observer that tests the RegionObserver interface. It works with
TestRegionObserverInterface to provide the test case.
hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/SimpleRegionObserver.java