以下设置不匹配，WPF MVVM单元测试与起订量

Question

我在WPF编写单元测试与起订量来测试用户是否点击了一个YesNoCancel MessageBox中的“是”按钮时，他们关闭窗户。在我CloseCommand我在我的视图模型给出了当用户关闭窗口下面的消息：

var result = _messageSvc.Show(
    "Do you want to save changes?", 
    "Save Changes", 
    Services.MessageBoxButton.YesNoCancel, 
    Services.MessageBoxIcon.Question, 
    Services.MessageBoxResult.Yes); 

我_messageSvc是一个自定义邮件服务以显示消息框内部的私有实例。下面是服务的代码：

public interface IMessageSvc 
{ 
    void Show(string message); 
    MessageBoxResult Show(string message, string caption, MessageBoxButton buttons, MessageBoxIcon icon, MessageBoxResult defaultResult = 0); 
} 

public class MessageSvc : IMessageSvc 
{ 
    public void Show(string message) 
    { 
     MessageBox.Show(message); 
    } 

    public MessageBoxResult Show(string message, string caption, MessageBoxButton buttons, MessageBoxIcon icon, MessageBoxResult defaultResult) 
    { 
     return (MessageBoxResult)MessageBox.Show(message, caption, (System.Windows.MessageBoxButton)buttons, (System.Windows.MessageBoxImage)icon, (System.Windows.MessageBoxResult)defaultResult); 
    } 
} 

注：MessageBoxButton，MessageBoxIcon，并MessageBoxResult是枚举我在同一个文件进行模仿什么.NET提供开箱即用的。我不向他们展示这里的可读性

我的单元测试的缘故：

[TestMethod] 
public void ShouldAskToSaveOnCloseRespondYesTest() 
{ 
    // Mock and setup initial user data 
    var u= new User 
    { 
     UserId = 1, 
     UserName = "FirstName LastName", 
     FavoriteColor = "Blue" 
    }; 
    mainViewModel.UserInfo= new UserInfoDtoWrapper(u); 

    // assert the data has not changed yet 
    Assert.IsFalse(mainViewModel.UserInfo.IsChanged); 

    // change the user data 
    mainViewModel.UserInfo.UserName= "LastName FirstName"; 

    // assert the data has changed 
    Assert.IsTrue(mainViewModel.UserInfo.IsChanged); 

    // execute window closing 
    mainViewModel.CloseCommand.Execute(new object()); 

    // verify messagebox shows and the 'Yes' button is clicked 
    // this will then save the changes made to the user instance 
    var messageBox = new Mock<IMessageSvc>(); 
    messageBox.Setup(x => x.Show(It.Is<string>(y => y == "Do you want to save changes?"), 
     It.Is<string>(y => y == "Save Changes"), 
     It.Is<MessageBoxButton>(y => y == MessageBoxButton.YesNoCancel), 
     It.Is<MessageBoxIcon>(y => y == MessageBoxIcon.Question), 
     It.Is<MessageBoxResult>(y => y == MessageBoxResult.Yes))) 
     .Returns(MessageBoxResult.Yes); 

    messageBox.Verify(); 
} 

的错误出现在messageBox.Verify()线，但是从我所看到的，我做正确。我需要获取消息框的返回值，以继续测试用户单击“是”按钮后发生的情况，所以我不想在内部使用带有Linq查询的Verify，而是需要捕获结果。

谢谢

Answer 1

这是行不通的。你在你的测试代码2个问题：

1. 你先火CloseCommand（假定调用IMessageSvc.Show方法），然后才安装了该服务的模拟。

2. 您为服务设置了一个新的模拟，但不使用它。

要纠正这些错误：

• 更改顺序，这是一个正确的“安排” - “行动” - “断言”为了
• 注入你的嘲笑服务视图模型使用依赖注入

下面是一个例子：

class MainViewModel 
{ 
    private readonly IMessageSvc _messageSvc; 

    public MainViewModel(IMessageSvc svc) 
    { 
     this._messageSvc = svc; 
    } 
} 

[TestMethod] 
public void ShouldAskToSaveOnCloseRespondYesTest() 
{ 
    // Arrange 
    var messageBox = new Mock<IMessageSvc>(); 
    messageBox.Setup(x => x.Show(It.Is<string>(y => y == "Do you want to save changes?"), 
     It.Is<string>(y => y == "Save Changes"), 
     It.Is<MessageBoxButton>(y => y == MessageBoxButton.YesNoCancel), 
     It.Is<MessageBoxIcon>(y => y == MessageBoxIcon.Question), 
     It.Is<MessageBoxResult>(y => y == MessageBoxResult.Yes))) 
     .Returns(MessageBoxResult.Yes) 
     .Verifiable(); 

    var mainViewModel = new MainViewModel(messageBox.Object); 

    // Act 
    mainViewModel.CloseCommand.Execute(new object()); 

    // Assert 
    messageBox.Verify(); 
} 

Answer 2

当前你正在设置你的模拟方法后测试将调用它的代码。重新安排您的测试AAA (Arrange, Act, Assert)模式像这样：

var messageBox = new Mock<IMessageSvc>(); 
messageBox.Setup(x => x.Show(It.Is<string>(y => y == "Do you want to save changes?"), 
    It.Is<string>(y => y == "Save Changes"), 
    It.Is<MessageBoxButton>(y => y == MessageBoxButton.YesNoCancel), 
    It.Is<MessageBoxIcon>(y => y == MessageBoxIcon.Question), 
    It.Is<MessageBoxResult>(y => y == MessageBoxResult.Yes))) 
    .Returns(MessageBoxResult.Yes); 

mainViewModel.CloseCommand.Execute(new object()); 

messageBox.Verify(x => x.Show(It.Is<string>(y => y == "Do you want to save changes?"), 
    It.Is<string>(y => y == "Save Changes"), 
    It.Is<MessageBoxButton>(y => y == MessageBoxButton.YesNoCancel), 
    It.Is<MessageBoxIcon>(y => y == MessageBoxIcon.Question), 
    It.Is<MessageBoxResult>(y => y == MessageBoxResult.Yes)));