Add safety around vignette engine when no quarto is available

R/utils-vignettes.R

@@ -20,6 +20,19 @@ vig_engine <- function(..., quarto_format) {
 vweave_quarto <- function(format) {
   meta <- get_meta(format)
   function(file, driver, syntax, encoding, quiet = FALSE, ...) {
+    # protect if Quarto is not installed
+    if (is.null(quarto_path())) {
+      msg <- c(
+        "Quarto binary is required to build Quarto vignettes but is not available.",
+        i = "Please make sure it is installed and found by {.code find_quarto()}."
+      )
+      if (is_R_CMD_check()) {
+        cli::cli_inform(msg)
+      } else {
+        cli::cli_abort(msg, call = NULL)
+      }
+      return(vweave_empty(file))
+    }
     quarto_render(file, ..., output_format = format, metadata = meta)
   }
 }
@@ -29,6 +42,18 @@ get_meta <- function(format) {
   if (format == "html") {
     return(get_meta_for_html())
   }
+  if (format == "pdf") {
+    return(get_meta_for_pdf())
+  }
+}
+
+get_meta_for_pdf <- function() {
+  meta <- list()
+  meta$format$pdf <- list(
+    # don't try to install CTAN package on CRAN environment
+    `latex-auto-install` = !is_cran_check()
+  )
+  meta
 }
 
 get_meta_for_html <- function() {
@@ -45,3 +70,25 @@ get_meta_for_html <- function() {
     )
   meta
 }
+
+is_R_CMD_check <- function() {
+  !is.na(Sys.getenv("_R_CHECK_PACKAGE_NAME_", NA)) ||
+    tolower(Sys.getenv("_R_CHECK_LICENSE_")) == "true"
+}
+
+# from knitr internal
+is_cran_check <- function() {
+  is_cran() && is_R_CMD_check()
+}
+
+is_cran = function() {
+  !rlang::is_interactive() && !isTRUE(as.logical(Sys.getenv("NOT_CRAN", "false")))
+}
+
+# trick from knitr to avoid problem on R CMD check (e.g. when no Quarto available)
+# It will silently skip the vignette
+vweave_empty <- function(file, ..., .reason = 'Quarto') {
+  out <- sprintf("%s.html", tools::file_path_sans_ext(basename(file)))
+  writeLines(sprintf("The vignette could not be built because %s is not available.", .reason), out)
+  out
+}

tests/testthat/test-utils-vignettes.R

@@ -0,0 +1,16 @@
+test_that("don't auto install CTAN package on CRAN", {
+  skip_on_cran()
+  skip_if_not_installed("withr")
+  withr::with_envvar(list(
+    # simulate non CRAN
+    "NOT_CRAN" = "false",
+    # simulate R CMD check
+    "_R_CHECK_LICENSE_" = "true"), {
+    expect_false(get_meta_for_pdf()$format$pdf$`latex-auto-install`)
+  })
+  withr::with_envvar(list(
+    "_R_CHECK_PACKAGE_NAME_" = NA
+  ), {
+    expect_true(get_meta_for_pdf()$format$pdf$`latex-auto-install`)
+  })
+})