public void adding_an_item_updates_the_current()
{
var model = new PostedTimeCollectionModel();
var observer = model.CreateObserver();
var current = PT(35d, PostedTimeType.Normal, 5);
model.Add(current);
Assert.Equal(current, model.Current);
current = PT(65d, PostedTimeType.Normal, 5);
model.Add(current);
Assert.Equal(current, model.Current);
Assert.Equal(2, observer.GetChangeCount(x => x.Current));
}