public void CovariantTest()
{
const int numberInRange = 100;
List <int> data = Enumerable.Range(0, numberInRange).ToList();
string expectedResult = string.Join(",", data);
IRunOnceEnumerable <ChildClass> e = data.Select(s => new ChildClass(s)).OnlyRunOnce();
// This is really a compiler time test.
// This method will only be callable if IRunOnceEnumerable is covariant.
// It will produce a compiler error otherwise.
string actualResult = CovariantAction(e);
Assert.AreEqual(expectedResult, actualResult);
}
private string CovariantAction(IRunOnceEnumerable <ParentClass> data)
{
return(string.Join(",", data.Select(d => d.StringData)));
}
