Question

嗨，我想知道是否有人知道我的问题的答案：

考虑以下代码

class TheHandler
{
    ...
    Public EventHandler myRealWorldEvent;
    ...


}

class TheSubscriber
{
    private TheHandler myHandler = new TheHandler();

    public subscribeToHandler()
    { 
        myHandler.myRealWorldEventHandler += OnSomethingHappens;

    }

     ...

    pirvate OnSomeThingHappens()
    {
       ...
    }
}

我的问题是 - ＆gt;我如何测试（仅限NUnit）OnSomethingHappens订阅了myRealWorldEventHandler。我不能改变SUT /生产代码，我不能模拟（Moq / Nmock等）。有谁知道我的问题的解决方案？

致以最诚挚的问候，

zhengtonic

Answer 1

NUnit不这样做 - 测试某些私有处理程序是否订阅了某些私有字段。涉及太多私人物品。但是，从反射中获得一些帮助，你无能为力。请注意，这不是漂亮的代码：

var subscriber = new TheSubscriber();
var handlerField = typeof(TheSubscriber)
    .GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
    // if field with such name is not present, let it fail test
    .First(f => f.Name == "myHandler");

var handlerInstance = handlerField.GetValue(subscriber);
var someEventField = typeof(TheHandler)
    .GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
    .First(f => f.Name == "myRealWorldEvent");

var eventInstance = (EventHandler) someEventField.GetValue(handlerInstance);
var subscribedMethod = eventInstance
    .GetInvocationList()
    .FirstOrDefault(d => d.Method.Name == "OnSomethingHappens");

Assert.That(subscribedMethod, Is.Not.Null);

如果你必须处理许多遗留系统测试（即私有成员，静态成员 - 免费框架无法正常处理的东西），我建议你看一下像{{}这样的工具。 3}}或TypeMock。

Answer 2

有同样的问题。来自jimmy_keen的代码与旧.NET无法正常工作。通过编写辅助方法来解决它：

public static void assertSubscribed<EventHandlerType>(object handler, object subscriber, string eventName = null) {
    var inappropriate = false;
    try {
        if (!typeof (EventHandlerType).IsSubclassOf(typeof (Delegate)) ||
            typeof (EventHandlerType).GetMethod("Invoke").ReturnType != typeof (void))
            inappropriate = true;
    } catch (AmbiguousMatchException) {
        inappropriate = true;
    } finally {
        if (inappropriate) throw new Exception("Inappropriate Delegate: " + typeof (EventHandlerType).Name);
    }

    var handlerField = subscriber.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
        .First(h => h.FieldType.IsInstanceOfType(handler));

    var handlerInstance = handlerField == null ? null : handlerField.GetValue(subscriber);
    var eventField = handlerInstance == null ? null : handlerInstance.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
        .First(f => (f.FieldType.IsAssignableFrom(typeof (EventHandlerType)) &&
                     (eventName == null || eventName.Equals(f.Name))));

    var eventInstance = eventField == null ? null : (Delegate)eventField.GetValue(handlerInstance);
    var subscribedMethod = eventInstance == null
        ? null 
        :eventInstance.GetInvocationList().FirstOrDefault(
            d => d.Method.DeclaringType != null && d.Method.DeclaringType.IsInstanceOfType(subscriber));

    Assert.That(subscribedMethod, Is.Not.Null);
}

＆＃34;不＆＃34;方法：

public static void assertNotSubscribed<EventHandlerType>(object handler, object subscriber, string eventName = null) {
    var inappropriate = false;
    try {
        if (!typeof (EventHandlerType).IsSubclassOf(typeof (Delegate)) ||
            typeof (EventHandlerType).GetMethod("Invoke").ReturnType != typeof (void))
            inappropriate = true;
    } catch (AmbiguousMatchException) {
        inappropriate = true;
    }
    if (inappropriate) return;

    var handlerField = subscriber.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
        .First(h => h.FieldType.IsInstanceOfType(handler));

    var handlerInstance = handlerField == null ? null : handlerField.GetValue(subscriber);

    var eventField = handlerInstance == null ? null : handlerInstance.GetType()
        .GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
        .First(f => (f.FieldType.IsAssignableFrom(typeof (EventHandlerType)) &&
                     (eventName == null || eventName.Equals(f.Name))));

    var eventInstance = eventField==null?null:(Delegate) eventField.GetValue(handlerInstance);
    var subscribedMethod = eventInstance == null
        ? null
        : eventInstance.GetInvocationList().FirstOrDefault(
                d => d.Method.DeclaringType != null && d.Method.DeclaringType.IsInstanceOfType(subscriber));

    Assert.That(subscribedMethod, Is.Null);
}

并且调用：

assertSubscribed<EventHandler>(handler, subscriber);
assertNotSubscribed<EventHandler>(handler, subscriber);
assertSubscribed<EventHandler>(handler, subscriber, "myRealWorldEvent");
assertNotSubscribed<EventHandler>(handler, subscriber, "myRealWorldEvent");

不要为代码风格惯例而烦恼，但这种方法看起来很紧凑。

如何使用NUnit对事件订阅进行单元测试

2 个答案: