Make `getNamespaceVersion()` work with temporary packages created with `usethis::create_package()`

[arangaca]

I wrote a package to cite other R packages. I use dummy packages created with usethis::create_package() for testing.

I'd like to use getNamespaceVersion() (rather than packageVersion()) to get package versions because it's faster, returns a character vector by default and is a bit cleaner in my opinion. The problem is that getNamespaceVersion() requires to have package metadata files to work, which is not the case of the fake packages I use.

local({
  local_pkg <- function(Package, ..., env = parent.frame()) {
    dir <- withr::local_tempdir(.local_envir = env)
    withr::local_libpaths(dir, action = "prefix", .local_envir = env)
    pkg_path <- file.path(dir, Package)
    usethis::ui_silence(
      usethis::create_package(
        path = pkg_path,
        fields = list(Type = "Package", Package = Package, ...),
        rstudio = FALSE,
        open = FALSE
      )
    )
  }
  
  local_pkg(
    "foo",
    Title = "Bar",
    `Authors@R` = utils::person("X", "Y", role = "aut"),
    Version = "1.0.0",
    Date = "2020-01-01"
  )
  
  getNamespaceVersion("foo")
})
#> <NA> 
#>   NA 
#> Warning message:
#> In loadNamespace(name) : package ‘foo’ has no 'package.rds' in Meta/

Is there an easy and efficient way to create or emulate the files needed to make getNamespaceVersion() work with such temporary packages?

[Gabor]

getNamespaceVersion() only works if you install the package first. Alternatively, you can also load it with pkgload::load_all().

[arangaca]

Installing the package isn't fast enough but pkgload::load_all() works like a charm.

[arangaca]

I may have talked a bit too soon. It works in all cases except when I render a .Rmd document in a callr subprocess, in which case it returns NA again.

Here's how I implemented load_all():

local_pkg <- function(Package, ..., env = parent.frame()) {
  dir <- withr::local_tempdir(.local_envir = env)
  withr::local_libpaths(dir, action = "prefix", .local_envir = env)
  pkg_path <- file.path(dir, Package)
  usethis::ui_silence(
    usethis::create_package(
      path = pkg_path,
      fields = list(Type = "Package", Package = Package, ...),
      rstudio = FALSE,
      open = FALSE
    )
  )
  devtools::load_all(pkg_path, export_all = FALSE, quiet = TRUE)
}

I use callr:r() with the default arguments.

Here's a reproducible example using the code on this repo:

# devtools::load_all()
local({
  load_foo()
  dir <- local_files(make_template(lines = "`r pkrt(foo)`"))
  read_local_file(dir)
})

[Gabor]

Again, you either need to install the package, or use pkgload::load_all(), this time in the callr subprocess.