sclass ErrorCounter {
  new LPair<O, Throwable> errors;
  int total;

  void run(O info, Runnable r) {
    try {
      r.run();
    } catch print e {
      errors.add(pair(info, e));
    }
    ++total;
  }
  
  void print() {
    _print(toString_short() +
      (nempty(errors) ? "" : ". Fails: " + pairsA(errors)));
  }
  
  S toString_short() {
    ret empty(errors)
      ? "No errors (tests: " + total + ")"
      : n2(errors, "error") + " in " + n2(total, "test") + ". Fails: " + pairsA(errors);
  }
  
  void add(ErrorCounter ec) {
    if (ec == null) ret;
    total += ec.total;
    addAll(errors, ec.errors);
  }
  
  bool allCorrect() { ret empty(errors); }
}