>It's a given that software needs to be tested. The processes around that are a classical "it depends" question.
Yes. What you need to do to ensure the correctness of flight software for a jet fighter is entirely different than what you need to do to ensure the correctness of an internal tool at your company that automates a task for which you already have a manual process.
It's a given that software needs to be tested. The processes around that are a classical "it depends" question.
Most likely any software you deploy will never be "correct" (whatever that means). The quality of that software depends on many variables and it's up to you to try and tweak them while optimizing for things like cost, time etc. Whether it's worthwhile to write the tests ahead of time or after the fact or to do them manually or automatically or any other permutation is just not a question that can be answered in a way that applies to all situations.