Testing any piece of software is extremely important but if this software happens to be an iOS/Mac app, testing is crucial. Apple’s App Store Review Guidelines provide developers with some insight (some) on how they can avoid getting their app rejected. I say ‘some’ because its a living document that constantly changes. Quotes from the guidelines:
This document represents our best efforts to share how we review apps submitted to the App Store, and we hope it is a helpful guide as you develop and submit your apps. It is a living document that will evolve as we are presented with new apps and situations, and we’ll update it periodically to reflect these changes.