Model-View-ViewModel in WPF

using CodeProject.VisualStudio.QualityTools.UnitTestFramework;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using TaskList.DataModel;
using TaskList.ViewModel;

namespace Test.TaskList.ViewModel
{
    [TestClass]
    public class TaskListPageViewModelTest
    {
        private class TaskListPageView : ITaskListPageView
        {
            public bool CreateNewTaskCalled { get; set; }
            public bool EditTaskCalled { get; set; }

            #region ITaskListPageView Members

            public Task CreateNewTask()
            {
                CreateNewTaskCalled = true;
                return null;
            }

            public void EditTask(Task task)
            {
                EditTaskCalled = true;
            }

            #endregion
        }

        public TaskListPageViewModelTest()
        {
        }

        private TestContext testContextInstance;

        public TestContext TestContext
        {
            get
            {
                return testContextInstance;
            }
            set
            {
                testContextInstance = value;
            }
        }

        private TaskListPageView view;
        private TaskListTestApplication application;
        private TaskListPageViewModel viewModel;

        #region Additional test attributes
        //
        // You can use the following additional attributes as you write your tests:
        //
        // Use ClassInitialize to run code before running the first test in the class
        // [ClassInitialize()]
        // public static void MyClassInitialize(TestContext testContext) { }
        //
        // Use ClassCleanup to run code after all tests in a class have run
        // [ClassCleanup()]
        // public static void MyClassCleanup() { }
        //
        // Use TestInitialize to run code before running each test 
        // [TestInitialize()]
        // public void MyTestInitialize() { }
        //
        // Use TestCleanup to run code after each test has run
        // [TestCleanup()]
        // public void MyTestCleanup() { }
        //
        [TestInitialize]
        public void TestInitialize()
        {
            view = new TaskListPageView();
            viewModel = new TaskListPageViewModel(view);
            viewModel.TaskListApplication = application = new TaskListTestApplication();
        }
        #endregion

        [TestMethod]
        public void TaskListCommands_AddTask_should_be_enabled()
        {
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.AddTask);
            Specify.That(tester.CanExecute()).ShouldBeTrue();
        }

        [TestMethod]
        public void AddTask_should_add_task()
        {
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.AddTask);
            Task item = new Task() { Title = "xyzzy" };
            tester.Execute(item);
            Specify.That(viewModel.Tasks[0]).ShouldBeSameAs(item);
        }

        [TestMethod]
        public void AddTask_should_call_ITaskListPageView_CreateNewTask_if_no_task_supplied()
        {
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.AddTask);
            tester.Execute();
            Specify.That(view.CreateNewTaskCalled).ShouldBeTrue();
        }

        [TestMethod]
        public void TaskListCommands_RemoveTasks_should_be_enabled_when_tasks_selected()
        {
            Task item = new Task() { Title = "xyzzy" };
            viewModel.Tasks.Add(item);
            viewModel.SelectedTasks.Add(item);
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.RemoveTasks);
            Specify.That(tester.CanExecute()).ShouldBeTrue();
        }

        [TestMethod]
        public void TaskListCommands_RemoveTasks_should_not_be_enabled_when_no_tasks_selected()
        {
            Task item = new Task() { Title = "xyzzy" };
            viewModel.Tasks.Add(item);
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.RemoveTasks);
            Specify.That(tester.CanExecute()).ShouldBeFalse();
        }

        [TestMethod]
        public void RemoveTasks_should_remove_selected_tasks()
        {
            Task item = new Task() { Title = "xyzzy" };
            viewModel.Tasks.Add(item);
            viewModel.SelectedTasks.Add(item);
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.RemoveTasks);
            tester.Execute();
            Specify.That(viewModel.Tasks).ShouldBeEmpty();
        }

        [TestMethod]
        public void EditTask_should_be_enabled_when_one_task_selected()
        {
            Task item = new Task() { Title = "xyzzy" };
            viewModel.Tasks.Add(item);
            viewModel.SelectedTasks.Add(item);
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.EditTask);
            Specify.That(tester.CanExecute()).ShouldBeTrue();
        }

        [TestMethod]
        public void EditTask_should_not_be_enabled_when_no_task_selected()
        {
            Task item = new Task() { Title = "xyzzy" };
            viewModel.Tasks.Add(item);
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.EditTask);
            Specify.That(tester.CanExecute()).ShouldBeFalse();
        }

        [TestMethod]
        public void EditTask_should_not_be_enabled_when_multiple_tasks_selected()
        {
            Task item = new Task() { Title = "xyzzy" };
            viewModel.Tasks.Add(item);
            viewModel.SelectedTasks.Add(item);
            item = new Task() { Title = "sesame" };
            viewModel.Tasks.Add(item);
            viewModel.SelectedTasks.Add(item);
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.EditTask);
            Specify.That(tester.CanExecute()).ShouldBeFalse();
        }

        [TestMethod]
        public void EditTask_should_call_ITaskListPageView_EditTask()
        {
            Task item = new Task() { Title = "xyzzy" };
            viewModel.Tasks.Add(item);
            viewModel.SelectedTasks.Add(item);
            CommandTester tester = new CommandTester(viewModel, TaskListCommands.EditTask);
            tester.Execute();
            Specify.That(view.EditTaskCalled).ShouldBeTrue();
        }
    }
}