Setting command line arguments for package installation

[kkmann]

I opened this issue in {pak} before, but I think it is better addressed in {pkgdepends}. Here is the link to the original issue https://github.com/r-lib/pak/issues/514.

I would like to test installed packages using tools::testInstalledPackage(), see https://rdrr.io/r/tools/testInstalledPackage.html.

In order to run all R code in the examples, tests, and vignettes, examples and tests need to be explicitly installed during installation. For examples this is the default, for tests not.

In order to do that, one would have to set R CMD INSTALL --install-tests as installation command line argument.

I am not sure how to set command line arguments in a package installation plan.

It seems that this might already be possible, see the cmd_args argument in make_build_process() https://github.com/r-lib/pkgdepends/blob/6741f04bf5f7fc8d73d87b3a326b1bf5a3914a38/R/install-plan.R#L356-L357 but it is unlcear to me how to pass it from a package installation proposal since there is not configuation option matching the argument.