使用 Task.Run 内部调用的 Moq 方法进行单元测试

Question

我正在尝试在我想要测试的方法内模拟服务调用。

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

测试方法如下所示：

[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

您的代码是应用谦卑对象模式的典型情况。

在这种情况下，您所要做的就是提取Task.Run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);
}