R: Skip a vignette being run on CRAN R CMD check

Question

I have a number of vignettes in an R package that are slow to run. As I understand it, a CRAN R CMD check will not rebuild the vignette but will run its corresponding code.

Since the vignettes are slow to run, I don't think the adhere to the CRAN policy. But the vignettes are useful examples that have figures. So I was wondering if it's possible to skip running vignette code only for a CRAN R CMD check, a bit like you can skip a unit test using testthat::skip_on_cran()?

Albur

Look at R CMD check --help. – Sterilization

Aah okay thanks, I also wondered if there's a way to specify that CRAN uses this option? – Albur

You can also run (parts of) the vignettes and install them as pre-built documentation so that they don't run each time. That introduces a threat they stop working correctly and the need for you to rebuild them each time you update the package code, but can get you around this timing issue. – Cadi

@Albur Did you find a solution to skip running vignette code on CRAN? – Byplay

I had a work around but you prompted me to get to the bottom of this. I'll write up as a solution. – Albur

Answer 1

Dirk's comment about R CMD check is --helpful. You will see a --no-vignettes flag.

If you're using devtools from the R console, just use:

devtools::check(vignettes = FALSE)

Hogfish

Answer 2

I just found there is an environment variable used by devtools called NOT_CRAN, and we should be able to use the same ideas to check if things are being run as CRAN. I believe wrapping code in the following if statement will mean it is only run if you are not using the --as-cran statement.

if (identical(Sys.getenv("NOT_CRAN", unset = "true"), "true")) {
    ###CODE HERE###
}

I think even if this has been set by devtools it should still work.

Sources: Testing -- R Packages by Hadley Wickham; testthat package source; devtools package source.

Albur

The code runs both when I build the vignette and when I call devtools::check(), where cran = TRUE is the default and checks using the same settings as CRAN. I'll see if it works when I release on CRAN. – Byplay