@Test
  public void testBlocksizeDefaultsToTwiceHDFSBlockSize() throws IOException {
    TableName tableName = TableName.valueOf("test");
    final WALFactory walFactory = new WALFactory(TEST_UTIL.getConfiguration(), this.walProvider);
    Configuration conf = TEST_UTIL.getConfiguration();
    WALProvider provider = walFactory.getWALProvider();
    // Get a WAL instance from the provider. Check its blocksize.
    WAL wal = provider.getWAL(null);
    if (wal instanceof AbstractFSWAL) {
      long expectedDefaultBlockSize =
        WALUtil.getWALBlockSize(conf, FileSystem.get(conf), TEST_UTIL.getDataTestDir());
      long blocksize = ((AbstractFSWAL) wal).blocksize;
      assertEquals(expectedDefaultBlockSize, blocksize);
      LOG.info("Found blocksize of {} on {}", blocksize, wal);
    } else {
      fail("Unknown provider " + provider);
    }
  }
Test blocksize change from HBASE-20520 takes on both asycnfs and old wal provider. Hard to
verify more than this given the blocksize is passed down to HDFS on create -- not kept local to
the streams themselves.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALConfiguration.java