public void TestNext()
{
IEnumerable<DayOfWeek> collection = new DayOfWeek[] { DayOfWeek.Monday, DayOfWeek.Friday };
var iterator = new Iterator<DayOfWeek>(collection.GetEnumerator());
Assert.AreEqual(DayOfWeek.Monday, iterator.Next());
Assert.AreEqual(DayOfWeek.Friday, iterator.Next());
ExceptionAssert.Throws<InvalidOperationException>(() => iterator.Next());
}
