@Before
  public void setUp() throws IOException {
    fs = FileSystem.get(TEST_UTIL.getConfiguration());
  }
A kind of integration test at the intersection of {@link HFileBlock}, {@link CacheConfig}, and
{@link LruBlockCache}.
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/TestLazyDataBlockDecompression.java