public void SourceManipulation() { var numbers = new SynchronizedRangeObservableCollection <int>(System.Linq.Enumerable.Range(0, 10)); using var query = numbers.ActiveElementAtOrDefault(9); Assert.IsNull(query.OperationFault); Assert.AreEqual(9, query.Value); numbers.Remove(9); Assert.IsNull(query.OperationFault); Assert.AreEqual(0, query.Value); numbers.Add(30); Assert.IsNull(query.OperationFault); Assert.AreEqual(30, query.Value); numbers.Insert(9, 15); Assert.IsNull(query.OperationFault); Assert.AreEqual(15, query.Value); }