I believe that's naive. There is always a non-zero chance that deploying new code will cause an issue that is not covered by your unit tests or integration tes

I believe that's naive. There is always a non-zero chance that deploying new code will cause an issue that is not covered by your unit tests or integration tests. Good testing methodology means adding to your tests when you find such a case, not promising that all possible cases are covered all the time, because that's unreasonable, and the assumption that there's no way it could break on deploy is the kind of hubris that leads to breakages when you deploy.