public void SourceManipulation()
{
var numbers = new ObservableDictionary <int, int>(Enumerable.Range(0, 10).ToDictionary(i => i));
using var query = numbers.ActiveValueFor(9);
Assert.IsNull(query.OperationFault);
Assert.AreEqual(9, query.Value);
numbers.Remove(9);
Assert.IsNotNull(query.OperationFault);
Assert.AreEqual(0, query.Value);
numbers.Add(9, 30);
Assert.IsNull(query.OperationFault);
Assert.AreEqual(30, query.Value);
numbers[9] = 15;
Assert.IsNull(query.OperationFault);
Assert.AreEqual(15, query.Value);
}
