public void EnqueueItem() { // Arrange var queue = new ObservableQueue <string>(); var itemOne = "One"; var itemTwo = "Two"; var itemThree = "Three"; // Act queue.Enqueue(itemOne); queue.Enqueue(itemTwo); queue.Enqueue(itemThree); // Assert var firstItem = queue.FirstOrDefault(); Assert.AreEqual(itemThree, firstItem, "The queue was not in the correct order. The first item int he list should have been the last item added."); }