Public Service Announcement;
Test your shit!

That will be all!

Source: https://dev.to/stealthmusic/...

I mostly agree, but one point.

You definetly should aim for 100%. In my experience every code is testable. And if it's not, you probably made some hacky stuff.

100% doesn't mean that you tested everything anyway. It just says that it got used at least once. But it doesn't say that you actually tested it, just that the code got touched.