带有延时的C#单元测试通过调试，但在构建服务器上失败

我在ASP.NET core中有一个类，它使用Threading.Timer在给定的时间间隔内运行一个小任务（因为在core中Timer.Timer不可用）。现在，我编写了一个单元测试，用于检查作业的运行时间：

[Fact]
    public async void IntervalExecutionTest()
    {
        var target = new PeriodicaBackgroundJobRunner();
        var testJob = new PeriodicalJobForTest();

        target.Start(1/*run every second*/, testJob);

        await Task.Delay(2500).ContinueWith(c =>
        {
            Assert.Equal(3, testJob.ExecutedCounter);
        });
    }

测试作业如下所示：

 private class PeriodicalJobForTest : IPeriodicalJob
    {
        public int ExecutedCounter { get; private set; }

        public void Execute(object state)
        {
            this.ExecutedCounter++;
        }
    }

public class PeriodicaBackgroundJobRunner : IPeriodicaBackgroundJobRunner
{
    private Threading.Timer timer;

    public void Start(int interval, IPeriodicalJob job)
    {
        interval = Math.Max(interval, 1) * 1000;

        if (this.timer == null)
        {
            this.timer = new Timer(new TimerCallback(job.Execute), null, Timeout.Infinite, interval);
        }

        this.timer.Change(0, interval);
    }

    public void Stop()
    {
        if (this.timer != null)
        {
            this.timer.Change(Timeout.Infinite, Timeout.Infinite);
        }
    }
}

因此，在2,5秒的等待时间内，我预计它将在0,1和2上运行3次

在调试中，测试通过。但构建服务器失败，并显示“预期为3，实际为1”

为什么？有什么不同？一旦它实际部署到Azure，我在生产中也会遇到问题吗

注意：我还尝试了Thread.Sleep（），结果相同

为了防止问题实际发生在测试实现中的类上，该类如下所示：

 private class PeriodicalJobForTest : IPeriodicalJob
    {
        public int ExecutedCounter { get; private set; }

        public void Execute(object state)
        {
            this.ExecutedCounter++;
        }
    }

public class PeriodicaBackgroundJobRunner : IPeriodicaBackgroundJobRunner
{
    private Threading.Timer timer;

    public void Start(int interval, IPeriodicalJob job)
    {
        interval = Math.Max(interval, 1) * 1000;

        if (this.timer == null)
        {
            this.timer = new Timer(new TimerCallback(job.Execute), null, Timeout.Infinite, interval);
        }

        this.timer.Change(0, interval);
    }

    public void Stop()
    {
        if (this.timer != null)
        {
            this.timer.Change(Timeout.Infinite, Timeout.Infinite);
        }
    }
}

---

嗯，不确定问题到底是什么，但它与Threading.Timer有关。当我在没有计时器的情况下重写类时，测试运行良好：

public class PeriodicaBackgroundJobRunner : IPeriodicaBackgroundJobRunner
{
    private CancellationTokenSource cancellationToken;

    public void Start(int interval, IPeriodicalJob job)
    {
        Task.Run(async () =>
        {
            interval = Math.Max(interval, 1) * 1000;

            this.cancellationToken = new CancellationTokenSource();

            while (true)
            {
                job.Execute(null);
                await Task.Delay(interval, this.cancellationToken.Token);
            }
        });
    }

    public void Stop()
    {
        if (this.cancellationToken != null)
        {
            this.cancellationToken.Cancel();
        }
    }
}

---

嗯，不确定问题到底是什么，但它与Threading.Timer有关。当我在没有计时器的情况下重写类时，测试运行良好：

public class PeriodicaBackgroundJobRunner : IPeriodicaBackgroundJobRunner
{
    private CancellationTokenSource cancellationToken;

    public void Start(int interval, IPeriodicalJob job)
    {
        Task.Run(async () =>
        {
            interval = Math.Max(interval, 1) * 1000;

            this.cancellationToken = new CancellationTokenSource();

            while (true)
            {
                job.Execute(null);
                await Task.Delay(interval, this.cancellationToken.Token);
            }
        });
    }

    public void Stop()
    {
        if (this.cancellationToken != null)
        {
            this.cancellationToken.Cancel();
        }
    }
}

---

如果将

async void

更改为

async Task

，问题是否仍然存在？如果将

async void

更改为

async Task

，问题是否仍然存在。。。。。。。。