@Test
  public void testL2CacheWithInvalidBucketSize() {
    Configuration c = new Configuration(this.conf);
    c.set(HConstants.BUCKET_CACHE_IOENGINE_KEY, "offheap");
    c.set(BlockCacheFactory.BUCKET_CACHE_BUCKETS_KEY, "256,512,1024,2048,4000,4096");
    c.setFloat(HConstants.BUCKET_CACHE_SIZE_KEY, 1024);
    try {
      BlockCacheFactory.createBlockCache(c);
      fail("Should throw IllegalArgumentException when passing illegal value for bucket size");
    } catch (IllegalArgumentException e) {
    }
  }
Assert that when BUCKET_CACHE_COMBINED_KEY is false, the non-default, that we deploy
LruBlockCache as L1 with a BucketCache for L2.
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/TestCacheConfig.java