public void Transformations_Relational_Select1()
{
bool nextItemCalled = false;
int expectedResult = 1;
var select = source.Select(s => s.Length);
select.CollectionChanged += (o, e) =>
{
Assert.AreEqual(NotifyCollectionChangedAction.Add, e.Action);
Assert.AreEqual(expectedResult, e.NewItems[0]);
nextItemCalled = true;
};
select.AssertEmpty();
source.Add("a");
Assert.IsTrue(nextItemCalled);
select.AssertContainsOnly(1);
nextItemCalled = false;
expectedResult = 2;
source.Add("aa");
Assert.IsTrue(nextItemCalled);
select.AssertContainsOnly(1, 2);
nextItemCalled = false;
expectedResult = 0;
select.Successors.UnsetAll();
source.Add("");
Assert.IsFalse(nextItemCalled);
}