Add parsable-roxygen hook

[owenjonesuob]

As discussed in #562.

Things to note:

• Since roxygen2::parse_file() does actually parse the file, I think we have to allow this hook to fail in two ways:
  • If it catches a warning, it fails and explains that it's due to a roxygen error
  • If it catches an error, it fails in the same way as parsable-R
• I don't think we need to actually evaluate the code though, hence roxygen2::parse_file(..., env = NULL) - unless you can think of some reason why we would need to evaluate?
• Do we need to do anything to ensure that {roxygen2} is available?

---

Closes #562.

[lorenzwalthert]

Sorry @owenjonesuob for the delay. Here's my review:

If it catches a warning, it fails and explains that it's due to a roxygen error.

Can you tell me when a warning would be issued? Depending on that, maybe a flag --allow-warnings could govern the behaviour of whether or not a warning is elevated to an error. If unset, warnings are errors, as you suggest.

I don't think we need to actually evaluate the code though,

What speaks against it? Is it slower? I guess it requires the package to be loadable with pkgload::load_all()? This would imply that development dependencies need to be available. Also, parsing errors in code to be evaluated does not seem to get caught with roxygen2::parse_file('file.R') if I write this to file.R:

#' Initiate a pre-commit config file
#'
#' @param verbose way. `r 1+++++`
my_fun <- function(...) NULL

But roxygen2::roxygenize() afterwards catches the problem and a subsequent roxygen2::parse_file('file.R') as well. Not sure how we can catch this in the first place...

[lorenzwalthert]

Suggested change

	entry: Rscript /inst/hooks/exported/parsable-roxygen.R
	entry: Rscript inst/hooks/exported/parsable-roxygen.R

This must be a relative path, compare to other hooks.

[lorenzwalthert]

Can you make the roxygen comment more minimal here since you want to test is parsing R code?