public async Task MessageSession()
    {
        var context          = new TestableMessageSession();
        var subscribeOptions = new SubscribeOptions();

        subscribeOptions.RequireImmediateDispatch();
        await context.Subscribe(typeof(MyMessage), subscribeOptions);

        var unsubscribeOptions = new UnsubscribeOptions();

        unsubscribeOptions.RequireImmediateDispatch();
        await context.Unsubscribe(typeof(MyMessage), unsubscribeOptions);

        await Verify(context);
    }