如何对这个库进行单元测试?

我不确定我是否做对了。是否要检查外部库是否触发事件?或者你想检查一下你是否做了什么特别是在事件被触发的时候?

如果是后者,我会用一个模拟来做。但问题是,你的代码似乎很难测试,因为你在用户界面上做逻辑工作。试着写一个“被动的”视图,让一个演示者来做魔术。例如,通过使用“模型-视图-演示者”模式 http://msdn.microsoft.com/en-us/magazine/cc188690.aspx

然后整件事就会变成这样。

public class Model : IModel
{
    public event EventHandler<SampleEventArgs> Completed;

    public void LongRunningTask()
    {
        BackgroundWorker bw = new BackgroundWorker();
        bw.DoWork += this.bw_DoWork;
        bw.RunWorkerCompleted += this.bw_RunWorkerCompleted;
        bw.RunWorkerAsync();

    }

    private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        if (this.Completed != null)
        {
            this.Completed(this, new SampleEventArgs {Data = "Test"});
        }
    }

    private void bw_DoWork(object sender, DoWorkEventArgs e)
    {
        System.Threading.Thread.Sleep(5000);
    }
}

景色

    public Form1()
    {
        InitializeComponent();
    }

    public event EventHandler Button1Clicked;

    public void Update(string data)
    {
        this.label1.Text = data;
    }

    private void Button1Click(object sender, EventArgs e)
    {
        if (this.Button1Clicked != null)
        {
            this.Button1Clicked(this, EventArgs.Empty);
        }
    }

演示者

public class Presenter
{
    private readonly IForm1 form1;
    private readonly IModel model;

    public Presenter(IForm1 form1, IModel model)
    {
        this.form1 = form1;
        this.model = model;

        this.form1.Button1Clicked += this.Form1Button1Clicked;
        this.model.Completed += this.ModelCompleted;
    }

    private void ModelCompleted(object sender, SampleEventArgs e)
    {
        this.form1.Update(e.Data);
    }

    private void Form1Button1Clicked(object sender, EventArgs e)
    {
        this.model.LongRunningTask();
    }
}

var form = new Form1();
var model = new Model();
var presenter = new Presenter(form, model);
Application.Run(form);

然后你可以很容易的在单元测试中测试演示者。gui中的部分现在已经小到不需要测试了。

可能的测试是这样的

    [Test]
    public void Test()
    {
        var form1Mock = new Mock<IForm1>();
        var modelMock = new Mock<IModel>();

        var presenter = new Presenter(form1Mock.Object, modelMock.Object);

        modelMock.Setup(m => m.LongRunningTask()).Raises(m => m.Completed += null, new SampleEventArgs() { Data = "Some Data" });

        form1Mock.Raise(f => f.Button1Clicked += null, EventArgs.Empty);

        form1Mock.Verify(f => f.Update("Some Data"));
    } 

嗯,我相信 BackgroundWorker 使用当前 SynchronizationContext . 你可以实现你自己的子类 行绪 取决于 在另一个线程中运行)并调用 SetSynchronizationContext

您需要在测试中订阅事件,然后检查是否调用了处理程序。(Lambda表达式对此很好。)

例如,假设您有一个 它允许您仅在需要时运行所有工作,并在完成时告诉您,您的测试可能:

• 设置同步上下文
• 创建组件
• 呼叫 LongRunningTask()
• 确认尚未设置局部变量
• 使同步上下文完成其所有工作。。。等待它完成(超时)
• 确认本地变量现在已设置

无可否认,这都有点恶心。如果你 只是测试它正在做的工作,同时,那会容易得多。

您可以创建一个扩展方法来帮助将其转换为同步调用。您可以做一些调整,比如使它更通用,并传入超时变量,但至少它将使单元测试更易于编写。

static class FooExtensions
{
    public static SomeData WaitOn(this Foo foo, Action<Foo> action)
    {
        SomeData result = null;
        var wait = new AutoResetEvent(false);

        foo.Completed += (s, e) =>
        {
            result = e.Data; // I assume this is how you get the data?
            wait.Set();
        };

        action(foo);
        if (!wait.WaitOne(5000)) // or whatever would be a good timeout
        {
            throw new TimeoutException();
        }
        return result;
    }
}

public void TestMethod()
{
    var foo = new Foo();
    SomeData data = foo.WaitOn(f => f.LongRunningTask());
}

为了测试异步代码,我使用了类似的助手:

public class AsyncTestHelper
{
    public delegate bool TestDelegate();

    public static bool AssertOrTimeout(TestDelegate predicate, TimeSpan timeout)
    {
        var start = DateTime.Now;
        var now = DateTime.Now;
        bool result = false;
        while (!result && (now - start) <= timeout)
        {
            Thread.Sleep(50);
            now = DateTime.Now;
            result = predicate.Invoke();
        }
        return result;
    }
}

在测试方法中,然后调用如下内容:

Assert.IsTrue(AsyncTestHelper.AssertOrTimeout(() => changeThisVarInCodeRegisteredToCompletedEvent, TimeSpan.FromMilliseconds(500)));