Very interesting! This is really old wisdom which should be more widespread. A few words of caution in there for everyone, me included.

Might come in handy when Filelight is not available, I could see myself using this over SSH connections.

Interesting way to reason about tests and classify them. I think it can be more useful than the strict "unit" vs "integration" that is way too widespread.

Looks like an interesting device to tinker with.