Question

我正在使用 Moq 在 WPF 中编写单元测试，以测试用户是否点击了＆＃34;是＆＃34;关闭窗口时YesNoCancel MessageBox上的按钮。在我的CloseCommand我的ViewModel中，当用户关闭窗口时会显示以下消息：

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

我的_messageSvc是自定义Messaging服务中的私有实例，用于显示消息框。以下是该服务的代码：

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);
    }
}

注意：MessageBoxButton，MessageBoxIcon和MessageBoxResult是我在同一文件中创建的枚举，以模仿.NET提供的开箱即用功能。为了便于阅读，我没有在这里展示它们

我的单元测试是：

[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();
}

错误出现在messageBox.Verify()行，但从我可以看到的我正确地做到了。我需要获取消息框的返回值以继续测试用户单击＆＃34;是＆＃34;按钮，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。

由于

Answer 1

这不起作用。您的测试代码中有2个问题：

首先触发CloseCommand（假设调用IMessageSvc.Show方法），然后只为该服务设置模拟。
您为服务设置了新的模拟但不使用它。

纠正这些错误：

更改顺序，使其成为正确的'安排' - '行动' - '断言'命令
使用依赖注入

以下是一个例子：

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

目前，您正在测试调用它的代码之后设置模拟方法。将测试重新安排到AAA (Arrange, Act, Assert)模式中，如下所示：

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)));

以下设置未匹配，使用Moq进行WPF MVVM单元测试

2 个答案: