.NET 中的单元测试 System.Threading.Timer [英] Unit test System.Threading.Timer in .NET

问题描述

如何在 .NET 中对基于 System.Threading.Timer 的计时器进行单元测试System.Threading.Timer 有一个回调方法

How to unit test a timer based on System.Threading.Timer in .NET The System.Threading.Timer has a callback method

推荐答案

您可以通过不实际创建对 System.Threading.Timer 的直接依赖来对其进行单元测试.相反，创建一个 ITimer 接口，以及一个实现它的 System.Threading.Timer 的包装器.

You can unit-test it by not actually creating a direct dependency on System.Threading.Timer. Instead, create an ITimer interface, and a wrapper around System.Threading.Timer that implements it.

首先，您需要将回调转换为事件，以便将其作为接口的一部分:

First you need to convert the callback to an event, so that it can be made part of an interface:

public delegate void TimerEventHandler(object sender, TimerEventArgs e);

public class TimerEventArgs : EventArgs
{
    public TimerEventArgs(object state)
    {
        this.State = state;
    }

    public object State { get; private set; }
}

然后创建一个接口:

public interface ITimer
{
    void Change(TimeSpan dueTime, TimeSpan period);
    event TimerEventHandler Tick;
}

还有一个包装器:

public class ThreadingTimer : ITimer, IDisposable
{
    private Timer timer;

    public ThreadingTimer(object state, TimeSpan dueTime, TimeSpan period)
    {
        timer = new Timer(TimerCallback, state, dueTime, period);
    }

    public void Change(TimeSpan dueTime, TimeSpan period)
    {
        timer.Change(dueTime, period);
    }

    public void Dispose()
    {
        timer.Dispose();
    }

    private void TimerCallback(object state)
    {
        EventHandler tick = Tick;
        if (tick != null)
            tick(this, new TimerEventArgs(state));
    }

    public event TimerEventHandler Tick;
}

显然，您可以从 Threading.Timer 添加任何需要使用的构造函数和/或 Change 方法的重载.现在，您可以根据 ITimer 使用伪计时器对任何内容进行单元测试:

Obviously you would add whatever overloads of the constructor and/or Change method you need to use from the Threading.Timer. Now you can unit test anything depending on ITimer with a fake timer:

public class FakeTimer : ITimer
{
    private object state;

    public FakeTimer(object state)
    {
        this.state = state;
    }

    public void Change(TimeSpan dueTime, TimeSpan period)
    {
        // Do nothing
    }

    public void RaiseTickEvent()
    {
        EventHandler tick = Tick;
        if (tick != null)
            tick(this, new TimerEventArgs(state));
    }

    public event TimerEventHandler Tick;
}

每当你想模拟一个滴答声时，只需在假上调用 RaiseTickEvent 即可.

Whenever you want to simulate a tick, just call RaiseTickEvent on the fake.

[TestMethod]
public void Component_should_respond_to_tick
{
    ITimer timer = new FakeTimer(someState);
    MyClass c = new MyClass(timer);
    timer.RaiseTickEvent();
    Assert.AreEqual(true, c.TickOccurred);
}

这篇关于.NET 中的单元测试 System.Threading.Timer的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！