Frictionless WCF service consumption in Silverlight - Part 3: Benefits of transparent asynchrony with respect to unit testing

using System.Collections.ObjectModel;

using Microsoft.Silverlight.Testing;
using Microsoft.VisualStudio.TestTools.UnitTesting;

using Sample.Silverlight.WCF.Infrastructure;
using Sample.Silverlight.WCF.Web.Services;
using Sample.Silverlight.WCF.Tests.Clumsy.ServiceReference1;

namespace Sample.Silverlight.WCF.Tests.Clumsy
{
	public class TaskManagementViewModel : ViewModelBase
	{
		Task selected;

		public TaskManagementViewModel()
		{
			Tasks = new ObservableCollection<Task>();
		}

		public ObservableCollection<Task> Tasks
		{
			get; private set;
		}

		public Task Selected
		{
			get { return selected; }
			set
			{
				selected = value;
				NotifyOfPropertyChange(() => Selected);
			}
		}

		public void Activate()
		{
			var service = new TaskServiceClient();

			service.GetAllCompleted += (o, args) =>
			{
				if (args.Error != null)
					return;

				foreach (Task each in args.Result)
				{
					Tasks.Add(each);
				}

				Selected = Tasks[0];
			};
			
			service.GetAllAsync();
		}
	}

	[TestClass]
	public class TaskManagementViewModelFixture : SilverlightTest
	{
		[TestMethod]
		[Asynchronous]
		public void Should_query_service_for_current_tasks_on_first_activation()
		{
			// arrange
			var model = new TaskManagementViewModel();

			// this will be used as a wait handle for test completion 
			bool eventRaised = false;
			model.PropertyChanged += (o, args) =>
			{
				if (args.PropertyName == "Selected")
					eventRaised = true;
			};

			EnqueueConditional(() => eventRaised);

			// act
			model.Activate();

			// assert
			EnqueueCallback(() =>
			{
				Assert.AreEqual(2, model.Tasks.Count);
				Assert.AreSame(model.Tasks[0], model.Selected);
			});

			EnqueueTestComplete();
		}
	}
}