public void replacing_an_item_does_not_update_the_count()
{
var model = new PostedTimeCollectionModel();
var observer = model.CreateObserver();
model.Add(PT(1, PostedTimeType.Normal, 1));
observer.ClearChanges();
model.ReplaceCurrent(PT(10, PostedTimeType.Normal, 1));
Assert.Equal(1, model.Count);
Assert.False(observer.HasChanged(x => x.Count));
}