@Test
  public void testDataBlockSizeEncoded() throws Exception {
    // Make up a directory hierarchy that has a regiondir ("7e0102") and familyname.
    Path dir = new Path(new Path(this.testDir, "7e0102"), "familyname");
    Path path = new Path(dir, "1234567890");

    DataBlockEncoding dataBlockEncoderAlgo = DataBlockEncoding.FAST_DIFF;

    conf.setDouble("hbase.writer.unified.encoded.blocksize.ratio", 1);

    cacheConf = new CacheConfig(conf);
    HFileContext meta =
      new HFileContextBuilder().withBlockSize(BLOCKSIZE_SMALL).withChecksumType(CKTYPE)
        .withBytesPerCheckSum(CKBYTES).withDataBlockEncoding(dataBlockEncoderAlgo).build();
    // Make a store file and write data to it.
    StoreFileWriter writer = new StoreFileWriter.Builder(conf, cacheConf, this.fs)
      .withFilePath(path).withMaxKeyCount(2000).withFileContext(meta).build();
    writeStoreFile(writer);

    StoreFileInfo storeFileInfo =
      StoreFileInfo.createStoreFileInfoForHFile(conf, fs, writer.getPath(), true);
    HStoreFile storeFile = new HStoreFile(storeFileInfo, BloomType.NONE, cacheConf);
    storeFile.initReader();
    StoreFileReader reader = storeFile.getReader();

    Map<byte[], byte[]> fileInfo = reader.loadFileInfo();
    byte[] value = fileInfo.get(HFileDataBlockEncoder.DATA_BLOCK_ENCODING);
    assertEquals(dataBlockEncoderAlgo.name(), Bytes.toString(value));

    HFile.Reader fReader =
      HFile.createReader(fs, writer.getPath(), storeFile.getCacheConf(), true, conf);

    FSDataInputStreamWrapper fsdis = new FSDataInputStreamWrapper(fs, writer.getPath());
    long fileSize = fs.getFileStatus(writer.getPath()).getLen();
    FixedFileTrailer trailer = FixedFileTrailer.readFromStream(fsdis.getStream(false), fileSize);
    long offset = trailer.getFirstDataBlockOffset(), max = trailer.getLastDataBlockOffset();
    HFileBlock block;
    while (offset <= max) {
      block = fReader.readBlock(offset, -1, /* cacheBlock */
        false, /* pread */ false, /* isCompaction */ false, /* updateCacheMetrics */
        false, null, null);
      offset += block.getOnDiskSizeWithHeader();
      double diff = block.getOnDiskSizeWithHeader() - BLOCKSIZE_SMALL;
      if (offset <= max) {
        assertTrue(diff >= 0 && diff < (BLOCKSIZE_SMALL * 0.05));
      }
    }
  }
Check if data block encoding information is saved correctly in HFile's file info.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestHStoreFile.java