Allow alternative knitr engines (#1392)

Fixes #1149.

NEWS.md

@@ -1,5 +1,7 @@
 # roxygen2 (development version)
 
+* You can now use alternative knitr engines in markdown code blocks (#1149).
+
 * Fix bug interpolating the results of indented inline RMarkdown (#1353).
 
 * R6 documentation no longer shows inherited methods if there aren't any 

R/markdown.R

@@ -52,6 +52,12 @@ markdown <- function(text, tag = NULL, sections = FALSE) {
 #' plot(1:10)
 #' ```
 #'
+#' Alternative knitr engines:
+#'
+#' ```{verbatim}
+#' #| file = "tests/testthat/example.Rmd"
+#' ```
+#'
 #' Also see `vignette("rd-formatting")`.
 #'
 #' @param text Input text.
@@ -113,9 +119,9 @@ work_around_cmark_sourcepos_bug <- function(text, rcode_pos) {
 }
 
 is_markdown_code_node <- function(x) {
-  info <- str_sub(xml_attr(x, "info"), 1, 3)
+  info <- xml_attr(x, "info")
   str_sub(xml_text(x), 1, 2) == "r " ||
-    (!is.na(info) && info %in% c("{r ", "{r}", "{r,"))
+    (!is.na(info) && grepl("^[{][a-zA-z]+[}, ]", info))
 }
 
 parse_md_pos <- function(text) {

tests/testthat/_snaps/markdown.md

@@ -57,3 +57,28 @@
     [<text>:4] @description markdown translation failed
     x block quotes are not currently supported
 
+# alternative knitr engines
+
+    Code
+      print(out1 <- roc_proc_text(rd_roclet(),
+      "\n      #' Title\n      #'\n      #' Description.\n      #'\n      #' ```{verbatim}\n      #' #| file = testthat::test_path(\"example.Rmd\")\n      #' ```\n      #' @md\n      #' @name x\n      NULL\n    "))
+    Output
+      $x.Rd
+      % Generated by roxygen2: do not edit by hand
+      % Please edit documentation in ./<text>
+      \name{x}
+      \alias{x}
+      \title{Title}
+      \description{
+      Description.
+      }
+      \details{
+      \if{html}{\out{<div class="sourceCode default">}}\preformatted{```\{r\}
+      # comment
+      this <- 10
+      is <- this + 10
+      good <- this + is
+      }\if{html}{\out{</div>}}
+      }
+      
+

tests/testthat/example.Rmd

@@ -0,0 +1,5 @@
+```{r}
+# comment
+this <- 10
+is <- this + 10
+good <- this + is

tests/testthat/test-markdown.R

@@ -619,3 +619,20 @@ test_that("markup in headings", {
     )
   )
 })
+
+test_that("alternative knitr engines", {
+  expect_snapshot(
+    print(out1 <- roc_proc_text(rd_roclet(), "
+      #' Title
+      #'
+      #' Description.
+      #'
+      #' ```{verbatim}
+      #' #| file = testthat::test_path(\"example.Rmd\")
+      #' ```
+      #' @md
+      #' @name x
+      NULL
+    "))
+  )
+})