infer knitr, rmarkdown dependency for R scripts with YAML front-matter

NEWS.md

@@ -1,6 +1,9 @@
 
 # renv 1.1.0  (UNRELEASED)
 
+* `renv` now infers a dependency on `rmarkdown` and `knitr` for R scripts which
+  include YAML front-matter. (#2023)
+
 * The performance of `renv`'s built-in JSON reader has been improved. (#2021)
 
 * Fixed an issue where `renv` could erroneously create a binding called 'object'

R/dependencies.R

@@ -1100,8 +1100,19 @@ renv_dependencies_discover_r <- function(path  = NULL,
   }
 
   renv_dependencies_recurse(expr, callback)
-
   packages <- ls(envir = envir, all.names = TRUE)
+
+  # also try to detect knitr::spin() dependencies -- this needs to
+  # happen outside of the regular dependency discovery machinery
+  # as it will rely on checking comments in the document
+  #
+  # https://github.com/rstudio/renv/issues/2023
+  if (is.character(text) || is.character(path)) {
+    text <- text %||% readLines(path, n = 1L, warn = FALSE)
+    if (length(text) && grepl("^\\s*#'\\s*[-]{3}\\s*$", text[[1L]], perl = TRUE))
+      packages <- union(c("knitr", "rmarkdown"), packages)
+  }
+
   renv_dependencies_list(path, packages, dev = dev)
 }
 

tests/testthat/resources/knitr-spin.R

@@ -0,0 +1,8 @@
+#' ---
+#' title: Palmer Penguins
+#' author: Norah Jones
+#' date: 3/12/23
+#' format: html
+#' ---
+
+print(42)

tests/testthat/test-dependencies.R

@@ -625,3 +625,8 @@ test_that("dependencies() does not create 'object' in parent environment", {
   result <- dependencies("resources/code.R", quiet = TRUE)
   expect_false(exists("object", envir = environment(), inherits = FALSE))
 })
+
+test_that("R scripts that appear destined for knitr::spin() are detected", {
+  result <- dependencies("resources/knitr-spin.R", quiet = TRUE)
+  expect_contains(result$Package, c("knitr", "rmarkdown"))
+})