@Test
public void testBadIndex() throws Exception {

  final int parts = 30;
  fs.delete(p, true);
  conf.setInt(TTConfig.TT_INDEX_CACHE, 1);
  IndexCache cache = new IndexCache(conf);
  Path f = new Path(p, "badindex");
  FSDataOutputStream out = fs.create(f, false);
  CheckedOutputStream iout = new CheckedOutputStream(out, new CRC32());
  DataOutputStream dout = new DataOutputStream(iout);
  for (int i = 0; i < parts; ++i) {
    for (int j = 0; j < MapTask.MAP_OUTPUT_INDEX_RECORD_LENGTH / 8; ++j) {
      if (0 == (i % 3)) {
        dout.writeLong(i);
      } else {
        out.writeLong(i);
      }
    }
  }
  out.writeLong(iout.getChecksum().getValue());
  dout.close();
  try {
    cache.getIndexInformation("badindex", 7, f,
      UserGroupInformation.getCurrentUser().getShortUserName());
    fail("Did not detect bad checksum");
  } catch (IOException e) {
    if (!(e.getCause() instanceof ChecksumException)) {
      throw e;
    }
  }
}