sclass Test_PairCollector {
  PairCollector<S, Int> collector;
  S result;
  
  void makeCollector {
    collector = new PairCollector;
    swap method collector.complete(a, b) {
      result = "Got " + a + " + " + b;
    }
    result = null;
  }
  
  run {
    makeCollector();
    collector.setA("Hello");
    assertNull(result);
    collector.setB(123);
    assertEqualsVerbose(result, "Got Hello + 123");

    makeCollector();
    collector.setterForB().get(456);
    assertNull(result);
    collector.setterForA().get("Yo");
    assertEqualsVerbose(result, "Got Yo + 456");
  }
}