@Test
  public void testBucketAllocatorLargeBuckets() throws BucketAllocatorException {
    long availableSpace = 20 * 1024L * 1024 * 1024;
    int[] bucketSizes = new int[] { 1024, 1024 * 1024, 1024 * 1024 * 1024 };
    BucketAllocator allocator = new BucketAllocator(availableSpace, bucketSizes);
    assertTrue(allocator.getBuckets().length > 0);
  }
<pre>
The asserts here before HBASE-21957 are:
assertEquals(1L, cache.getBlockCount());
assertTrue(cache.getCurrentSize() > 0L);
assertTrue("We should have a block!", cache.iterator().hasNext());

The asserts here after HBASE-21957 are:
assertEquals(0, cache.getBlockCount());
assertEquals(cache.getCurrentSize(), 0L);

I think the asserts before HBASE-21957 is more reasonable,because
{@link BucketCache#evictBlock} should only evict the {@link BucketEntry}
it had seen, and newly added Block after the {@link BucketEntry}
it had seen should not be evicted.
</pre>
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestBucketCache.java