@Test
  public void testReferenceSize() {
    LOG.info("ClassSize.REFERENCE is " + ClassSize.REFERENCE);
    // oop should be either 4 or 8
    assertTrue(ClassSize.REFERENCE == 4 || ClassSize.REFERENCE == 8);
  }
Testing the classes that implements HeapSize and are a part of 0.20. Some are not tested here
for example BlockIndex which is tested in TestHFile since it is a non public class
hbase-server/src/test/java/org/apache/hadoop/hbase/io/TestHeapSize.java