新浪微博客户端围脖七开发笔记（2） 添加更多测试到MainPageViewModel

想了一个礼拜，究竟是先实现些具体功能呢，还是继续完善TDD，还是先后者吧：具体功能无非就是些api的调用，wp7的twiter或者围脖的例子也有一些了，也不少我这一篇:)

1. 准备几个基本类，status，user和SinaService接口

    public class User
    {
        public ulong Id { get; set; }
        public string ScreenName { get; set; }
        public string ImageUrl { get; set; }
        public string Name { get; set; }
        public string Url { get; set; }
        public string Description { get; set; }
        public string Location { get; set; }
        public int Followers { get; set; }
        public int Friends { get; set; }
        public DateTime CreatedAt { get; set; }
    }

    public class Status
    {
        public Status()
        {
            User = new User();
        }

        public DateTime CreatedAt { get; set; }        

        public ulong Id { get; set; }       
                     
        public string Text { get; set; }

        public string Source { get; set; }

        public User User { get; set; }

        public bool Favorited { get; set; }

        public int RetweetCount { get; set; }

        public bool Retweeted { get; set; }

    }

    /// <summary>
    /// A simple Sina service interface
    /// </summary>
    public interface ISinaService
    {
        /// <summary>
        /// Get statuses from sina weibo
        /// </summary>
        /// <param name="onGetStatusesCompleted">the callback method</param>
        /// <param name="onError"></param>
        /// <param name="onFinally"></param>
        void GetStatuses(Action<IEnumerable<Status>> onGetStatusesCompleted = null, Action<Exception> onError = null, Action onFinally = null);
    }

status和user类的相应测试俺就偷懒不写了，读者有兴趣可以自己试试！

 

2. 修改下MainPageViewModel， 加入SinaService接口和HomeList，前者用来调用sina的接口取得数据，后者是最新微博的容器。注意把它们设置为internal，方便测试项目调用，还要添加如下一行在AssemblyInfo.cs中：

[assembly: InternalsVisibleTo("WeiBo7.Test")]

 

    public class MainPageViewModel : ViewModelBase
    {
        internal readonly ISinaService SinaService;   
        private bool _isHomeRefreshing = false;        
               
        public MainPageViewModel()
        {
            SinaService = new SinaService();
            HomeList = new ObservableCollection<Status>();
           
        }

        public ObservableCollection<Status> HomeList { get; internal set; }
        
        /// <summary>
        /// Indicates whether there is an indeterminate operation in progress
        /// </summary>
        public bool IsHomeRefreshing
        {
            get { return _isHomeRefreshing; }
            set
            {
                if (value != _isHomeRefreshing)
                {
                    _isHomeRefreshing = value;
                    OnNotifyPropertyChanged("IsHomeRefreshing");
                }
            }
        }         

    }

3. 现在转到测试项目，先加入一个TestInitialize方法，在所有的测试方法前做些准备工作：

 

        private MainPageViewModel _mainViewModel;

        [TestInitialize]
        public void Initialize()
        {
            _mainViewModel = new MainPageViewModel();
        }

还可以加入一个[TestCleanup]方法：

        [TestCleanup]
        public void CleanUp()
        {
            
        }

目前没干什么事情，但对于任何一个测试方法，执行顺序是TestInitialize->test method->TestCleanup, 这样保证每个测试方法是彼此独立，互不影响，不用在每个测试方法里面都初始化，节省些代码。

4. 在MainPageViewModelTests先添加一个negative test, 看下这个类如何应对NullInstance

 

        [TestMethod]
        [ExpectedException(typeof(NullReferenceException))]
        public void NullInstance()
        {
            _mainViewModel = null;
            bool x = _mainViewModel.IsHomeRefreshing; 
        }

5. 测试初始化是否成功

 

        [TestMethod]
        public void Init_MainPageViewModel_Success()
        {
            Assert.IsNotNull(_mainViewModel);
            Assert.IsNotNull(_mainViewModel.HomeList);
            Assert.IsNotNull(_mainViewModel.SinaService); 
            Assert.IsInstanceOfType(_mainViewModel, typeof(INotifyPropertyChanged));
        }

 6. 测试当添加一个item到HomeList时，是否CollectionChanged被fire 

 

        [TestMethod]
        public void AddItem_HomeList_RaisesCollectionChanged()
        {
            bool changeObserved = false;
            _mainViewModel.HomeList.CollectionChanged +=
                (s, e) =>
                {                    
                    changeObserved = true;
                    Assert.AreEqual(NotifyCollectionChangedAction.Add, e.Action);
                    Assert.AreEqual(1, e.NewItems.Count, "only should be +1 item");                    
                };

            _mainViewModel.HomeList.Add(new Status());
            Assert.IsTrue(changeObserved);
        }

最后运行如下图：