c# - 试图理解 MockSequence

Question

我目前正在编写一个应用程序，为了测试它的行为是否正确，我需要验证方法是否按给定顺序调用。

对于我的单元测试，我使用 xUnit和 Moq

现在，为什么我需要测试调用的顺序？

我正在开发一个在不同线程上执行任务的解决方案。一旦执行任务，我就会向给定的记录器写入一条消息，因此通过检查对记录器的调用顺序，我可以确保我的代码已正确实现。

在这里查看我正在尝试使用的代码:

public class SchedulerFixture
{
    #region Constructors

    public SchedulerFixture()
    {
        LoggerMock = new Mock<ILogger>(MockBehavior.Strict);

        // Setup of other mocks removed for simplicity.
    }

    #endregion
}

public class SequentialTaskExecutorMock : SchedulerFixture
{
    [Fact]
    public void Should_WriteTheCorrectLogEntries_WhenTasksAreExecutedAndNotCancelled()
    {
        // Defines the task that needs to be executed.
        var task = new LongRunningServiceTaskImplementation();

        // Built a sequence in which logs should be created.
        var sequence = new MockSequence();

        LoggerMock.Setup(x => x.Information(It.IsAny<string>(), It.IsAny<string>())).Verifiable();

        LoggerMock.InSequence(sequence).Setup(x => x.Information("émqsdlfk", "smdlfksdmlfk")).Verifiable();
        LoggerMock.InSequence(sequence).Setup(x => x.Information(LoggingResources.LoggerTitle, LoggingResources.Logger_ServiceStopped)).Verifiable();
        LoggerMock.InSequence(sequence).Setup(x => x.Information(LoggingResources.LoggerTitle, LoggingResources.Logger_ServiceStarted)).Verifiable();
        LoggerMock.InSequence(sequence).Setup(x => x.Information(LoggingResources.LoggerTitle, string.Format(CultureInfo.InvariantCulture, LoggingResources.Logger_TaskCompleted, task.TaskName))).Verifiable();
        LoggerMock.InSequence(sequence).Setup(x => x.Information(LoggingResources.LoggerTitle, LoggingResources.Logger_ServiceStopped)).Verifiable();

        // Setup the mock required for the tests.
        TaskGathererMock.Setup(x => x.GetServiceTasks(LoggerMock.Object)).Returns(() =>
        {
            return new[] { task };
        });

        // Start the scheduler.
        Scheduler.Start(TaskGathererMock.Object, ConfigurationManagerMock.Object);

        // Wait for 5 seconds (this simulates running the service for 5 seconds).
        // Since our tasks execution time takes 4 seconds, all the assigned tasks should have been completed.
        Thread.Sleep(5000);

        // Stop the service. (We assume that all the tasks have been completed).
        Scheduler.Stop();

        LoggerMock.VerifyAll();
    }
}

因此，我测试的第一步是设置日志，然后执行测试本身(这会调用记录器)，最后我会验证它。

但是，测试总是通过。

在这种情况下它应该失败，因为下面的调用:

LoggerMock.InSequence(sequence).Setup(x => x.Information("émqsdlfk", "smdlfksdmlfk")).Verifiable();

没有在我的代码中的任何地方执行。

Answer 1

虽然这确实感觉像是 Moq 中的错误(请参阅 Patrick Quirk 对该问题的第一条评论)，但这里有一个粗略的想法，您可以改为执行此操作。这是一种“长评论”。

创建一个简单的类:

class SequenceTracker
{
    int? state;

    public void Next(int newState)
    {
        if (newState <= state)
            Assert.Fail("Bad ordering there! States should be increasing.");

        state = newState;
    }
}

然后像这样使用它(你自己的代码的修改版本):

public void Should_WriteTheCorrectLogEntries_WhenTasksAreExecutedAndNotCancelled()
{
    // Defines the task that needs to be executed.
    var task = new LongRunningServiceTaskImplementation();

    // USE THE CLASS I PROPOSE:
    var tracker = new SequenceTracker();


    //LoggerMock.Setup(x => x.Information(It.IsAny<string>(), It.IsAny<string>()))

    LoggerMock.Setup(x => x.Information("émqsdlfk", "smdlfksdmlfk"))
        .Callback(() => tracker.Next(10));
    LoggerMock.Setup(x => x.Information(LoggingResources.LoggerTitle, LoggingResources.Logger_ServiceStopped))
        .Callback(() => tracker.Next(20));
    LoggerMock.Setup(x => x.Information(LoggingResources.LoggerTitle, LoggingResources.Logger_ServiceStarted))
        .Callback(() => tracker.Next(30));
    LoggerMock.Setup(x => x.Information(LoggingResources.LoggerTitle, string.Format(CultureInfo.InvariantCulture, LoggingResources.Logger_TaskCompleted, task.TaskName)))
        .Callback(() => tracker.Next(40));
    LoggerMock.Setup(x => x.Information(LoggingResources.LoggerTitle, LoggingResources.Logger_ServiceStopped))
        .Callback(() => tracker.Next(50));

    // Setup the mock required for the tests.
    TaskGathererMock.Setup(x => x.GetServiceTasks(LoggerMock.Object)).Returns(() =>
    {
        return new[] { task };
    });

    // Start the scheduler.
    Scheduler.Start(TaskGathererMock.Object, ConfigurationManagerMock.Object);

    // Wait for 5 seconds (this simulates running the service for 5 seconds).
    // Since our tasks execution time takes 4 seconds, all the assigned tasks should have been completed.
    Thread.Sleep(5000);

    // Stop the service. (We assume that all the tasks have been completed).
    Scheduler.Stop();

    // THIS NOW WORKS BECAUSE WE ABANDONED THE 'MockSequence' APPROACH:
    LoggerMock.VerifyAll();
}

当然，如果需要，这可以做得更高级。