This one is a bit tricky, because you have to think about logging as an output or a side-effect. And as an industry, we’ve been learning that we should limit the amount of side-effects that our code generates.

If logging is getting ingested by downstream systems like CloudWatch, or other structured logging systems, it is potentially going to be used to detect service issues and track overall service health. These are logs that are serving a functional purpose that is not purely a side-effect, or for debugging forensics.

If this is the case, then you should have a unit test asserting that a log entry is emitted when a method is called. If writing that test is a low or non-priority, then even if it’s a “breaking change,” then that’s a sign that it’s not actually going to break anyone.

I’m sure there’s some monadic view of how to package up the “side-effect” logging as part of a function’s output, but it’s probably annoying to implement in most languages.