private static final long EXPIRING_TIME = 1000;
  private static final int VALUE_PREFIX = 12345;
  private static final String KEY_PREFIX = "key prefix:";

  public void testExpiration_expireAfterWrite() {
    FakeTicker ticker = new FakeTicker();
    CountingRemovalListener<String, Integer> removalListener = countingRemovalListener();
    WatchedCreatorLoader loader = new WatchedCreatorLoader();