}

      @Override
      public void tearDown() throws IOException {
        factory.tearDown();
      }
    };
  }

  public static ByteSourceFactory asSlicedByteSourceFactory(
      ByteSourceFactory factory, long off, long len) {
    checkNotNull(factory);
    return new ByteSourceFactory() {
      @Override
      public ByteSource createSource(byte[] bytes) throws IOException {