MediatR generic notification handler not called

Hi,

I'm starting to use MediatR's notification.

In one handler, I want to "log" every notification that comes through. According to what I found (https://stackoverflow.com/questions/70852634/mediatr-doesnt-handle-contravariant-notifications), I tried the following:

The NotificationHandler:

public class NotificationLogger<T> : INotificationHandler<T>
    where T : INotification
{
    private readonly ILogger<NotificationLogger<T>> _logger;
    public NotificationLogger(ILogger<NotificationLogger<T>> logger)
    {
        _logger = logger;
    }
    public Task Handle(T notification, CancellationToken cancellationToken)
    {
        _logger.LogTrace($"[{notification.GetType().Name}]: {notification} ");
        return Task.CompletedTask;
    }
}

One of my notification:

public class ServerStartedNotification : ISystemNotification
{
}
public class ISystemNotification : INotification
{
}

I register the notification handler:

app.Services.AddTransient(typeof(NotificationLogger<>));

In my Program.cs, I publish the notification just before waiting on the application:

using (IServiceScope? scope = app.Services.CreateScope())
{
    scope.ServiceProvider.GetRequiredService<IMediator>().Publish(new ServerStartedNotification()).Wait();
}
app.Run();

All my breakpoints gets hit, except the NotificationLogger.Handle.

Any idea why and what I could check?

jbogard / MediatR

MediatR generic notification handler not called #761