The Unit Test of Silverlight Applications with Asynchronous Service Callbacks

using System;
using Microsoft.Silverlight.Testing;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using SilverlightApplication.ViewModels;

namespace SilverlightApplicationUnitTest
{
    [TestClass]
    public class MainPageViewModelTests: SilverlightTest
    {
        [TestMethod]
        public void ViewModelInitiation()
        {
            MainPageViewModel vm = new MainPageViewModel();
            Assert.IsTrue(vm.StudentList == null, 
                "At view model initiation, StudentList should be null");
            Assert.IsTrue(vm.GetStudentWCFCommand != null,
                "At view model initiation, GetStudentWCFCommand should be initiated");
            Assert.IsTrue(vm.GetStudentWCFWrongMethodCommand != null,
                "At view model initiation, GetStudentWCFWrongMethodCommand should be initiated");
        }

        [TestMethod]
        [Asynchronous]
        public void AsynchronousWCFCallWithGetStudentWCFCommand()
        {
            MainPageViewModel vm = new MainPageViewModel();
            bool done = false;
            vm.AsyncCallbackCompleted += (() => done = true);

            EnqueueCallback(() => vm.GetStudentWCFCommand.Execute(null));
            EnqueueConditional(() => done);
            EnqueueCallback(() => Assert.IsNotNull(vm.StudentList,
                "No student retreived from the WCF service"));
            EnqueueCallback(() => Assert.IsTrue(vm.StudentList.Count == 10,
                "The number of the students should be 10."));

            EnqueueTestComplete();
        }

        [TestMethod]
        [Asynchronous]
        public void AsynchronousWCFCallWithGetStudentWCFWrongMethodCommand()
        {
            MainPageViewModel vm = new MainPageViewModel();
            bool done = false;
            vm.AsyncCallbackCompleted += (() => done = true);

            EnqueueCallback(() => vm.GetStudentWCFWrongMethodCommand.Execute(null));
            EnqueueConditional(() => done);
            EnqueueCallback(() => Assert.IsNotNull(vm.StudentList,
                "No student retreived from the WCF service"));
            EnqueueCallback(() => Assert.IsTrue(vm.StudentList.Count == 10,
                "The number of the students should be 10. Problem is captured by the unit test."));

            EnqueueTestComplete();
        }
    }
}