"Program testing can be used to show the presence of bugs, but never to show their absence!"
- Edsger W. Dijkstra
This is easily one of my favorite quotes when it comes to software engineering. And something I like to mention to less technical people when I hear it's an all new platform and everything is tested. Or an odd engineer saying "this will never break". Although, I think there's another saying for that.
Don't let your coverage numbers fool you! We hope for the best, but we should be prepared for the worst.