Re: How to trigger actions
I did not find any test modules. What I did was leverage the Workflow app. If I know what data is being sent from the Zuora notification and what the json looks like, I build a similar 'notification' as a workflow. Basically use an 'Export' task to spit out the relevant data, interate over each record, then a 'Callout' task to mold the data into what the json would look like and to send a callout to an external api.
You can infer what the conditions would be when using the 'Export' task.
Not perfect, but at least it helps move forward with testing things like 30 day notices. Otherwise you're waiting a day to test once.