Why should I use asserts?

Question

I never got the idea of asserts -- why should you ever use them?

I mean, let\'s say I were a formula driver and all the asserts were things like security belt, helm

Answer 1

Just don't use Assertions when you don't want. There is nothing wrong not to use it.

Assertion is only helpful when a test case in debug mode actually hit it. Many times it doesn't hit at all, depends on quality of your test cases. Assertion is used when you try to verify an assumption, so you got what you asked for, you hardly break your assumption during test. That's why you assume it in first place isn't it. Yet there are endless number of "expected impossible" cases that really don't hit your assertion during debug, but somehow still hit in production which have assertion disabled. If you rely on assertion during debug then you most likely end up having some unexpected thing happen in production that even your assertion didn't catch.

Your program should be designed in a strategic way, so that even unexpected matter happen or your test cases didn't cover, a problem is still handled in a defined way, or produce meaningful diagnostic info.

You can use assertion to help troubleshooting, but it is not helpful if you want to prevent problem from happening in first place. The reason is that you can't prevent or handle a niche problem if you assume it won't happen in production (you disable assertion in Production). Good software should catch obvious errors (assertion helps), as well as niche errors (assertion probably won't help).

Many people will tell you a standard version of what is assertion supposed to do. What assertion is good for etc. But please justify by your own experience if it is really helpful or not. Assertion is not scientific proven or golden rule, it is just a practice of many people. You should decide to adopt it or not by yourself.