public void GetOrAddTest()
{
IWDT iwdt = new IWDT();
var ret = iwdt.GetOrAdd(HT(1, 1), Tuple.Create(2, 1));
Assert.AreEqual(Tuple.Create(2, 1), ret);
Assert.AreEqual(Tuple.Create(2, 1), iwdt.GetItem(HT(1, 1)));
ret = iwdt.GetOrAdd(HT(1, 1), Tuple.Create(3, 1));
Assert.AreEqual(Tuple.Create(2, 1), ret);
Assert.AreEqual(Tuple.Create(2, 1), iwdt.GetItem(HT(1, 2)));
iwdt.Keys[Tuple.Create(1, 1)].IsGarbage = true;
ret = iwdt.GetOrAdd(HT(1, 2), Tuple.Create(3, 1));
Assert.AreEqual(Tuple.Create(3, 1), ret);
Assert.AreEqual(Tuple.Create(3, 1), iwdt.GetItem(HT(1, 2)));
}