How to unit test helper methods in Python scheduled job?

I've read quite a few answers on here about testing helper methods (not necessarily private) in my unit tests and I'm still not quite sure what the best approach should be for my current situation.

I currently have a block of logic that runs as a scheduled job. It does a number of mostly related things like update local repositories, convert file types, commit these to other repos, clean up old repos, etc. I need all of this code to run in a specific order, so rather than setting a bunch of scheduled jobs, I took a lot of these small methods and put them into one large method that would enforce the order in which the code is run:

def mainJob():
    run_a()
    run_b()
    run_c()

and so on. Now I'm not sure how to write my tests for this thing. It's frustrating to test the entire mainJob() function because it does so many things and is really more of a reliability feature anyway. I see a lot of people saying I should only test the public interface, but I worry that there will potentially be code that isn't directly verified.