Source an RMD file

source_rmd.R

#' Source the R code from an knitr file, optionally skipping plots
#'
#' @param file the knitr file to source
#' @param skip_plots whether to make plots. If TRUE (default) sets a null graphics device
#'
#' @return This function is called for its side effects
#' @export
source_rmd = function(file, skip_plots = TRUE) {
  temp = tempfile(fileext=".R")
  knitr::purl(file, output=temp)

  if(skip_plots) {
    old_dev = getOption('device')
    options(device = function(...) {
      .Call("R_GD_nullDevice", PACKAGE = "grDevices")
    })
  }
  source(temp)
  if(skip_plots) {
    options(device = old_dev)
  }
}

One limitation is that knitr::purl() can fail if using this function in an .Rmd (due to duplicate chunk labels) -- a fix is to wrap the purl call in callr::r() which I describe here: https://stackoverflow.com/a/71119357/9059865