[Host.Outbox] Fails to retrieve bus when no child buses are in use

[EtherZa]

When SlimMessageBus is configured to use a primary (Main) bus only, the OutboxSendingTask fails to locate the bus.

I have narrowed the issue down to the OutboxSendingTask.GetBus method but unfortunately don't have the time to dig/resolve the issue for the time being.

    private static IMasterMessageBus GetBus(ICompositeMessageBus compositeMessageBus, IMessageBusTarget messageBusTarget, string name)
    {
        if (name != null && compositeMessageBus != null)
        {
            return compositeMessageBus.GetChildBus(name);
        }
        if (messageBusTarget != null)
        {
            return messageBusTarget.Target as IMasterMessageBus;
        }
        return null;
    }

Steps to reproduce:

1. Configure a bus (not a child bus) to use the Outbox plugin.
2. Publish a message so that it is spooled to sql
3. When OutboxSendingTask attempts to find the 'Main' bus, it will satisfy the condition first condition of the GetBus method and attempt to resolve a ChildBus instead of falling through to messageBusTarget.Target.
4. GetBus returns null, which aborts the message delivery

Workaround:

Configure SlimMessageBus to add the bus as a child.

builder.Services.AddSlimMessageBus(builder =>
{
    builder.AddChildBus("SVB", bus =>
    {
        ...
    });

    ...
});

[zarusz]

Thanks for reporting. I can have a look.