[Jtsummers]

It does make sense with new code, yes. Whether for all code or not, or whether unit tests or integration or end to end tests though is up to your judgement. No one but you, who knows your system and your capabilities and knowledge, can decide for you. Only fools expect a technique to replace thinking. I assume you're not a fool.

For new code, the reason it makes sense is that your system is bugged. It does not do what it's intended to do yet because you haven't written the code to do it (or altered the existing code to add the new capability). So the test detects the difference between the current state of the system and the desired state, and then you implement the code and now the test detects that you have achieved your desired state (at least as far as the test can detect, you could still have other issues).