public void service_on_clear_undo_entities_are_restored() { var source = new Person[] { new Person(null, false), new Person(null, false), new Person(null, false), new Person(null, false), new Person(null, false) }; ChangeTrackingService svc = new ChangeTrackingService(); PersonCollection list = new PersonCollection(svc); list.BeginInit(); list.AddRange(source); list.EndInit(); list.Clear(); svc.Undo(); Assert.AreEqual <int>(source.Length, list.Count()); source.ForEach(p => { int expected = Array.IndexOf(source, p); int actual = list.IndexOf(p); Assert.AreEqual <int>(expected, actual); }); }