Don't run go tests when only docs are changed

[sspaink]

Short description

Noticed in a recent PR that only changed one markdown file the entire Go workflow is run (build, tests, linting). We can detect what files are changed and only run the necessary checks. Not sure if there is a native way to do this in Github Actions but could use this project: https://github.com/dorny/paths-filter to filter based on files changed.

Expected behavior

Only the required tests are run depending on the files changed in the PR.

[srenatus]

This goes both ways, doesn't it? If a change only affects Go code, why build the docs on the PR?

[sspaink]

Good point! Would it be safe to assume that if nothing changed in the docs directory then the docs shouldn't be generated?

[srenatus]

Re: paths-filter, if we can get by with the simple built-in stuff, that would perhaps be better.

If I remember correctly, the website builds are triggered from netlify, I don't know if it's easy to make them conditional... 🤔

Would it be safe to assume that if nothing changed in the docs directory then the docs shouldn't be generated?

I think it's at least a good enough approximation. Even if something, like auto-generated CLI parameter docs, technically brings in a dependency between the Go code and the website (I might misremember things!), we still have a full build of the website on every push to main. (This is something to also reconsider, to waste less resources.)

[srenatus]

To be clear, any small improvement is well worth the while here. We don't need pull this all off right away.

[srenatus]

Just remembered that we already skip the website build if it's deemed unnecessary 😅 3b01b9a

[charlieegan3]

I think something like this would be preferred (over a new action step):

on:
  push:
    paths-ignore:
      - 'docs/**'

However, it'd involve breaking down our pr.yaml into separate workflows. I'm unsure if that's worse, I guess it means things are in lots of places...