@Override
      public void doAnAction() throws Exception {
        toBeTested.evictBlock(key);
        toBeTested.cacheBlock(key, bac);
        Thread.sleep(blockEvictPeriod);
      }
Just checks if heapsize grows when something is cached, and gets smaller when the same object
is evicted
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/CacheTestUtils.java