@Test
  public void shouldFailWhenFileDoesNotExist() throws Exception {
    FileStorage fileStorage = mock(FileStorage.class);
    when(fileStorage.exists("1/2/3")).thenReturn(false);

    BufferedLogReader logReader = new HessianBufferedLogReader();
    logReader.setFileStorage(fileStorage);

    IllegalArgumentException expected = null;
    try {
      logReader.read("1", "2", "3", Integer.class);
    } catch (IllegalArgumentException e) {
      expected = e;
    }
    assertThat(expected, notNullValue());
    verify(fileStorage).exists("1/2/3");
  }
  @Override
  public AggregationInfo chronology(String dir, String targetFile) throws IOException {
    log.info("Try to aggregate {} into file {}", dir, targetFile);
    Collection<Hessian2Input> inputStreams = new ArrayList<Hessian2Input>();
    Set<String> fileNameList = fileStorage.getFileNameList(dir);
    if (fileNameList.isEmpty()) {
      log.info("Nothing to aggregate. Directory {} is empty.", dir);
      new Hessian2Output(fileStorage.create(targetFile)).close();
      return new AggregationInfo(0, 0, 0);
    }
    for (String fileName : fileNameList) {
      try {
        InputStream in = fileStorage.open(fileName);
        inputStreams.add(new Hessian2Input(in));
      } catch (FileNotFoundException e) {
        log.warn(e.getMessage(), e);
      }
    }

    int count = 0;
    long minTime = 0;
    long maxTime = 0;

    Hessian2Output out = null;
    OutputStream os = null;
    try {
      if (fileStorage.delete(targetFile, false)) {
        log.warn("Target file {} did not deleted!", targetFile);
      }
      os = fileStorage.create(targetFile);
      out = new Hessian2Output(os);
      MinMaxPriorityQueue<StreamInfo> queue = MinMaxPriorityQueue.create();
      for (Hessian2Input inputStream : inputStreams) {
        LogEntry logEntry;
        try {
          logEntry = (LogEntry) inputStream.readObject();
        } catch (EOFException e) {
          continue;
        }
        queue.add(new StreamInfo(inputStream, logEntry));
      }

      while (!queue.isEmpty()) {
        StreamInfo<LogEntry> streamInfo = queue.removeFirst();
        out.writeObject(streamInfo.lastLogEntry);

        if (count == 0) {
          minTime = streamInfo.lastLogEntry.getTime();
          maxTime = streamInfo.lastLogEntry.getTime();
        } else {
          maxTime = streamInfo.lastLogEntry.getTime();
        }

        count++;
        LogEntry logEntry;
        try {
          logEntry = (LogEntry) streamInfo.stream.readObject();
        } catch (EOFException e) {
          continue;
        }
        streamInfo.lastLogEntry = logEntry;
        queue.add(streamInfo);
      }
    } finally {
      if (out != null) {
        out.close();
        os.close();
      }
    }

    return new AggregationInfo(minTime, maxTime, count);
  }