WeakEventManager - event handler is not called

Question

I am not able to reproduce the issue (and project is too big to post it here, plus I am not sure what are related parts to post) and I need ideas of what could go wrong here.

I have abstract class with static event

public abstract partial class A : Base
{
    public static event EventHandler Test;
    public static void OnTest() => Test?.Invoke(null, EventArgs.Empty);
}

Then I subscribe to this event normally and using WeakEventManager:

A.Test += (s, e) => { };
WeakEventManager<A, EventArgs>.AddHandler(null, nameof(A.Test), (s, e) => { });

And for some reasons weak event handler doesn't get fired when OnTest() is called. Everything (invoke and handlers) are operating in the UI thread.

I've set breakpoints:

1. On AddHandler(), it runs and the instance of class then persist.
2. On Invoke(), it runs when OnTest is called, I can see 2 subscribers if I call Test.GetInvocationList() one of them is DeliverEvent() from WeakEventManager, so event was registered and Invoke() should call weak event handler.
3. Inside normal event handler, it runs.
4. Inside weak event handler, nothing, this breakpoint never get hit.

Any ideas of why would this occur or what should I investigate?

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I've tried to look into .net sources, to find answers there, but there is ProtectedAddHandler which sources I can't find... I found it, but what is the next? Abstract method, who implements it?...

Answer 1

WeakEventManager ... not working event handler ...

To whoever face this issue, the problem is this: you must rise static event with null as sender! E.g. in my case it was (use this to reproduce issue with code in the question):

public static void OnTest() => Test?.Invoke("whatever", EventArgs.Empty);

This case will be handled by normal subscriber without any problem.

But in case of WeakEventManager it must be a null (special case), otherwise your event handler will not work.

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