I try to have "debug calls" that I can call from the browser or Postman or Swagger, etc. and return all sorts of debug information, etc. I have the impression

I try to have "debug calls" that I can call from the browser or Postman or Swagger, etc. and return all sorts of debug information, etc. I have the impression that local program-specific debugging tools quickly evolve into something like functional tests that uncover issues that functional tests proper might not cover. For example, if I'm serving a ML model but I have a debug call that runs sanity checks on the data that are too expensive to run each time.