public void AddRangeTest() { int didNotify = 0; MTObservableCollection <string> coll = new MTObservableCollection <string>(); coll.CollectionChanged += (s, e) => didNotify++; coll.AddRange(new[] { "One", "Two", "Three", "Four" }); Assert.AreEqual(4, coll.Count); Assert.AreEqual(1, didNotify); }