private void ApplyChangesAndTest(NotifyCollectionChangedEventArgs received, NotifyCollectionChangedAction Expected) { received.Should().NotBeNull(); received.Action.Should().Be(Expected); int c = _Target.Count; Nullable<int> changes = _Target.ApplyChanges(received); changes.Should().HaveValue(); _Target.Should().Equal(_Collection); changes.Should().Be(_Target.Count - c); }