simple pkgdown check

[gravesti]

First attempt to implement quick checks for {pkgdown}. Fixes #378

[lorenzwalthert]

@gravesti thanks for your work. This works now in principle. Only practical problem are the heavly dependencies, in particular in a CI setting. So, it may work best if you use {pkgdown} already locally and have all the system dependencies. {pkgdown} has many dependencies and system dependencies that are required to make loading the package not error, but not required for our functionality...

Probably, these checks would just be skipped in CI then.

Coming from the problem use case: {pkgdown} builds are only triggered on default branches, so even if a PR succeeds, we don't know if the pkgdown build will succeed. Hence, instead (or as a complement) of a pre-commit hook, the GitHub Action for pkgdown could also build the page and not deploy it. Should I file an issue in r-lib/actions for this?

[lorenzwalthert]

I thought about it again and I think we should merge the hook, but use system as a language, r. Hence, we'd fallback on the system installation of {pkgdown} and all dev dependencies of a package, which will anyways be installed if you use the hook. In CI setting, using the hook makes no sense. Also, the lastet version of the {pkgdown} action in r-lib/actions already builds PRs as if the were merged in main, so I guess that is also an improvement.

[gravesti]

I note that in the mean time pkgdown implemented a check_pkgdown() which could be used within the hook

[lorenzwalthert]

Thanks @gravesti. I spend at least 5h working on this PR (and some related issues that came up due to it) over the last 3 days. -.- I see that you mentioned that you opened an issue in {pkgdown}, can you please link it next time? Would have saved me a lot of time I think.

[lorenzwalthert]

@gravesti this will be available when there is a new release (i.e. new tag on main). Or if you use a hash pointing to HEAD (e.g. 59981a7) instead of a git tag.