public void WhenExceptionActionPassed_ThenItShouldBeInvokedOnException() { var system = new ActorSystem(); IBus bus = null; system.Add(new ThrowingHandler(), ctx => { bus = ctx.Bus; }); Exception ex = null; var wait = new ManualResetEventSlim(false); system.Start(e => { ex = e; wait.Set(); }); var msg = new Message(); bus.Publish(ref msg); Assert.True(wait.Wait(TimeSpan.FromSeconds(10))); ExceptionHelpers.ExceptionOrAggregateWithOne(ex, ThrowingHandler.Exception); }