public void testAcrossMultipleBlocks() throws Exception {
    final int testLength = 3072;

    Random random = random();
    final PagedBytes p = new PagedBytes(10);
    final DataOutput out = p.getDataOutput();
    final byte[] bytes1 = new byte[4096];
    random.nextBytes(bytes1);
    out.writeBytes(bytes1, 0, bytes1.length);

    final PagedBytes.Reader reader = p.freeze(random.nextBoolean());
    BytesRef answer = reader.fillSlice(new BytesRef(), 0, testLength);
    assertEquals(testLength, answer.length);

    int lastOffset = 0;
    for(int i=0;i<testLength;i++) {
      lastOffset = answer.offset + i;
      if (bytes1[i] != answer.bytes[answer.offset + i])
        break;
    }
    assertEquals(testLength-1, lastOffset);
  }