@Override
  public void preGetOp(final ObserverContext<? extends RegionCoprocessorEnvironment> c,
    final Get get, final List<Cell> results) throws IOException {
    RegionCoprocessorEnvironment e = c.getEnvironment();
    assertNotNull(e);
    assertNotNull(e.getRegion());
    assertNotNull(get);
    assertNotNull(results);
    ctPreGet.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