使用在 Task.Run 内部调用的 Moq 方法进行单元测试

Question

我正在尝试在要测试的方法中模拟服务调用。

方法体如下所示：

public string OnActionException(HttpActionContext httpRequest, Exception ex)
{
    var formattedActionException = ActionLevelExceptionManager.GetActionExceptionMessage(httpRequest);

    var mainErrorMessage = $"[{formattedActionException.ErrorId}]{formattedActionException.ErrorMessage}, {ex.Message}";

    this.LogError(mainErrorMessage, ex);

    if (this._configuration.MailSupportOnException)
        Task.Run(async () => await this._mailService.SendEmailForThrownException(this._configuration.SupportEmail, $"{mainErrorMessage} ---> Stack trace: {ex.StackTrace.ToString()}")); 

    return $"(ErrID:{formattedActionException.ErrorId}) {formattedActionException.ErrorMessage} {formattedActionException.KindMessage}";
}

我在测试中试图模拟的是：

Task.Run(async () => await this._mailService.SendEmailForThrownException(this._configuration.SupportEmail, $"{mainErrorMessage} ---> 堆栈跟踪：{ex.StackTrace.ToString()}"));

测试方法如下：

[TestMethod]
public void We_Send_System_Exception_On_Email_If_Configured_In_Settings()
{
    // arrange
    this._configurationWrapperMock.Setup(cwm => cwm.MailSupportOnException)
        .Returns(true);
    this._mailServiceMock.Setup(msm => msm.SendEmailForThrownException(It.IsAny<string>(), It.IsAny<string>()))
        .Returns(Task.FromResult(0));

    // act
    var logger = new ApiLogger(this._configurationWrapperMock.Object, this._mailServiceMock.Object);
    logger.OnActionException(
        new HttpActionContext(
            new HttpControllerContext()
            {
                Request = new HttpRequestMessage()
                {
                    Method = HttpMethod.Get,
                    RequestUri = new System.Uri("https://www.google.bg/")
                }
            }, 
            new ReflectedHttpActionDescriptor() { }
        ), 
        new System.Exception());

    // assert
    this._mailServiceMock.Verify(
        msm => msm.SendEmailForThrownException(It.IsAny<string>(), It.IsAny<string>()), 
        Times.Once);
}

问题是该方法从未被调用，所以我的断言失败了。

编辑：我可以将我的问题更改为：我需要如何重写我的方法才能使其可测试？

Answer 1

我尝试了上面场景的一个简单的简化版本，并且单元测试始终通过。

public interface IService
{
    Task<bool> Do();
}

public class AsyncService : IService
{
    public async Task<bool> Do()
    {
        return await Task.FromResult(true);
    }
}

public class MyClass
{
    private IService service;

    public MyClass(IService service)
    {
        this.service = service;
    }

    public async Task<bool> Run()
    {
        return await this.service.Do();
    }
}

[TestMethod]
public async Task TestAsyncMethod()
{
    Mock<IService> mockService = new Mock<IService>();
    mockService.Setup(m => m.Do()).Returns(Task.FromResult(false));

    MyClass myClass = new MyClass(mockService.Object);
    await myClass.Run();

    mockService.Verify(m => m.Do(), Times.Once);
}

看起来您需要将 OnActionException return 设置为 Task，然后还使单元测试异步。因此，不是使用 Task.Run()，而是 return OnActionException 方法中的 await this._mailService.SendEmailForThrownException()。

Answer 2

我想出的解决方案是提取新的服务方法，它是 Sync，在其中我使用 Thead.Run.

在单独的线程中私下调用我的异步方法

public void ReportExceptionOnEmail(string recipient, string exceptionBody)
{
    Task.Run(async () => await this.SendEmailForThrownException(recipient, exceptionBody));
}

private async Task SendEmailForThrownException(string recipientEmail, string exceptionBody)

所以，现在我可以毫无问题地对 ReportExceptionOnEmail 方法进行单元测试。

Answer 3

您的代码是应用的经典情况Humble Object Pattern。

在这种情况下，您所要做的就是将 Task.Run 提取到虚拟方法中，然后部分模拟 SUT 并覆盖此虚拟方法：

public class ApiLogger
{
    ...

    public string OnActionException(Exception ex)
    {
        ...
        if (this._configuration.MailSupportOnException)
            RunInTask(...);
        ...
    }

    public virtual Task RunInTask(Action action)
    {
        return Task.Run(action);
    }
}

然后测试将如下所示：

[TestMethod]
public void We_Send_System_Exception_On_Email_If_Configured_In_Settings()
{
    ...

    var logger = new Mock<ApiLogger>(MockBehavior.Default, 
                                     new object[]
                                     {
                                       this._configurationWrapperMock.Object, 
                                       this._mailServiceMock.Object
                                     }).Object;

    logger.OnActionException(...);


    this._mailServiceMock.Verify(
            msm => msm.SendEmailForThrownException(It.IsAny<string>(), It.IsAny<string>()), 
            Times.Once);
}

使用在 Task.Run 内部调用的 Moq 方法进行单元测试

Unit testing with Moq method invoked inside of Task.Run

c#

unit-testing

assert

moq

mocking