Raise Async Event causes Method Signature Error

[Anthony]

For the sake of brevity, I've included a minimal example below. An async event MyEventAsync is defined in class MyClass. An event handler OnMyEventAsync is also defined.

public class MyClass
{
    // Event.
    public event Func<EventArgs, Task>? MyEventAsync;
}

// Event handler.
private Task OnMyEventAsync(EventArgs args) => Task.CompletedTask;

I then create a mock of MyClass and register the event handler OnMyEventAsync with the event MyEventAsync. Then Raise the event with the syntax given in the documentation.

// Create mock.
var mockClass = Mock.Create<MyClass>(Behavior.Strict);

// Register event handler.
mockClass.MyEventAsync += OnMyEventAsync;

// Raise event on mock.
Mock.Raise(() => mockClass.MyEventAsync += null, EventArgs.Empty);

But I receive the following error:

Telerik.JustMock.Core.MockException : Event signature System.Threading.Tasks.Task OnMyEventAsync(System.EventArgs) is incompatible with argument types (Castle.Proxies.ExternalMockMixinProxy, System.EventArgs)

I've probably missed something very obvious here. I know the above syntax should work with an event of type EventHandler<EventArgs>, but I'm not sure how to modify it to work with event of type Func<EventArgs, Task>. If anyone could clear up my confusion, I'd be most grateful. Thanks! =)

 

[Ivo]

Hello Anthony,

As you mentioned, Mock.Rise assumes that the event is EventHandler<EventArgs> compatible and tries to insert the missing argument for the sender behind the scenes. In this particular case, it becomes wrong and that is a root cause for this exception, I am afraid that it requires a change in JustMock code. Until we fix this issue, the workaround would be raising the event through reflection.

Regards,
Ivo
Progress Telerik

[Anthony]

Okay, just wanted to make sure that was the case. Thanks! =)

[Ivo]

Hey Anthony, we have already fixed the issue and will make it publicly available in 2024 the Q3 release. Thanks for your finding, we greatly appreciate it.

[Anthony]

Wow, that was fast! Thanks for everything, much appreciated! =)