private void insertData(CoherenceDirectory dir, String fileName) throws IOException {
    byte[] test = new byte[] {1, 2, 3, 4, 5, 6, 7, 8};
    IndexOutput indexOutput = dir.createOutput(fileName);
    indexOutput.writeBytes(new byte[] {2, 4, 6, 7, 8}, 5);
    indexOutput.writeInt(-1);
    indexOutput.writeLong(10);
    indexOutput.writeInt(0);
    indexOutput.writeInt(0);
    indexOutput.writeBytes(test, 8);
    indexOutput.writeBytes(test, 5);

    indexOutput.seek(0);
    indexOutput.writeByte((byte) 8);
    if (dir.getBucketSize() > 4) {
      indexOutput.seek(2);
      indexOutput.writeBytes(new byte[] {1, 2}, 2);
    }

    indexOutput.close();
  }