private void writePreviousTestRunId() {
    try {
      FileWriter writer = new FileWriter(new File(mDir, SCREENSHOT_TESTS_RUN_ID_FILE_NAME));
      writer.write(mCurrentTestRunId);
      writer.close();
    } catch (IOException e) {
      Log.e(AlbumImpl.class.getName(), "Couldn't write previous test run id.", e);
    }
  }
Creates a "local" album that stores all the images on device.
core/src/main/java/com/facebook/testing/screenshot/internal/AlbumImpl.java