public void RemoveWhere () { var set = new SortedSet<int> { 1, 2, 3, 4, 5, 6 }; Assert.AreEqual (3, set.RemoveWhere (i => i % 2 == 0)); Assert.AreEqual (3, set.Count); Assert.IsTrue (set.SequenceEqual (new [] { 1, 3, 5 })); }