单元测试从线程发射的事件

Question

我有一个问题单元测试一个类,当一个线程启动并完成时会触发事件.违规来源的简化版本如下:

public class ThreadRunner
{
    private bool keepRunning;

    public event EventHandler Started;
    public event EventHandler Finished;

    public void StartThreadTest()
    {
        this.keepRunning = true;
        var thread = new Thread(new ThreadStart(this.LongRunningMethod));
        thread.Start();
    }

    public void FinishThreadTest()
    {
        this.keepRunning = false;
    }

    protected void OnStarted()
    {
        if (this.Started != null)
            this.Started(this, new EventArgs());
    }

    protected void OnFinished()
    {
        if (this.Finished != null)
            this.Finished(this, new EventArgs());
    }

    private void LongRunningMethod()
    {   
        this.OnStarted();

        while (this.keepRunning)
            Thread.Sleep(100);

        this.OnFinished();
    }
}

然后我有一个测试来检查Finished事件在LongRunningMethod完成之后如下所示:

[TestClass]
public class ThreadRunnerTests
{
    [TestMethod]
    public void CheckFinishedEventFiresTest()
    {
        var threadTest = new ThreadRunner();

        bool finished = false;

        object locker = new object();

        threadTest.Finished += delegate(object sender, EventArgs e)
        {
            lock (locker)
            {
                finished = true;
                Monitor.Pulse(locker);
            }
        };

        threadTest.StartThreadTest();
        threadTest.FinishThreadTest();

        lock (locker)
        {
            Monitor.Wait(locker, 1000);
            Assert.IsTrue(finished);
        }
    }
}

所以这里的想法Finish是在检查finished标志是否设置之前,测试将阻塞最多一秒 - 或直到事件被触发.

很明显,我做错了,因为有时测试会通过,有时则不会.调试似乎非常困难,而且我期望被击中的断点(OnFinished例如,方法)似乎并不总是如此.

我假设这只是我对线程工作方式的误解,所以希望有人可以启发我.

Answer 1

锁在这里不合适,你想要发出一个事件的信号.例如:

    public void CheckFinishedEventFiresTest() {
        var threadTest = new ThreadRunner();
        var finished = new ManualResetEvent(false);
        threadTest.Finished += delegate(object sender, EventArgs e) {
            finished.Set();
        };
        threadTest.StartThreadTest();
        threadTest.FinishThreadTest();
        Assert.IsTrue(finished.WaitOne(1000));
    }