set gfm_auto_identifiers to input format if toc is TRUE

NEWS.md

@@ -21,6 +21,8 @@ rmarkdown 2.7
 
 - Eliminated the unnecessary padding in code blocks in the `html_document` output with Bootstrap 4 themes (thanks, @atusy, #2019).
 
+- `github_document()` will produce a working TOC even if some headers start with number (#2039)
+
 rmarkdown 2.6
 ================================================================================
 

R/github_document.R

@@ -52,6 +52,10 @@ github_document <- function(toc = FALSE,
     "--atx-headers", pandoc_args
   )
 
+  if (toc && !isTRUE(grepl("gfm_auto_identifiers", md_extensions))) {
+    md_extensions <- c(md_extensions, "+gfm_auto_identifiers")
+  }
+
   format <- md_document(
     variant = variant, toc = toc, toc_depth = toc_depth,
     number_sections = number_sections, fig_width = fig_width,

tests/testthat/_snaps/github_document/github-atx.md

@@ -0,0 +1,10 @@
+
+# title 1
+
+## title 2
+
+### title 3
+
+#### title 4
+
+##### title 5

tests/testthat/_snaps/github_document/github-toc.md

@@ -0,0 +1,11 @@
+
+-   [10 Section](#10-section)
+-   [Header](#header)
+
+# 10 Section
+
+Sentence.
+
+# Header
+
+Sentence

tests/testthat/helpers.R

@@ -0,0 +1,17 @@
+local_rmd_file <- function(..., .env = parent.frame()) {
+  path <- withr::local_tempfile(envir = .env, fileext = ".Rmd")
+  xfun::write_utf8(c(...), path)
+  path
+}
+
+skip_if_not_pandoc <- function(ver) {
+  if (!pandoc_available(ver)) {
+    skip(sprintf("Version of Pandoc is lower than %s.", ver))
+  }
+}
+
+skip_if_pandoc <- function(ver) {
+  if (pandoc_available(ver)) {
+    skip(sprintf("Version of Pandoc is greater than %s.", ver))
+  }
+}

tests/testthat/test-github_document.R

@@ -0,0 +1,23 @@
+
+test_that("toc has correct identifier", {
+  local_edition(3)
+  skip_on_cran() # avoid pandoc issue on CRAN
+  skip_if_not_pandoc("2.10.1") # changes in gfm writer break this test for earlier versions
+  tmp_file <- local_rmd_file(
+    c("# 10 Section","","Sentence.","", "# Header","","Sentence ")
+  )
+  res <- render(tmp_file, github_document(toc = TRUE, html_preview = FALSE))
+  expect_snapshot_file(res, "github-toc.md", binary = FALSE)
+})
+
+
+test_that("github_document produces atx-header", {
+  local_edition(3)
+  skip_on_cran() # avoid pandoc issue on CRAN
+  h <- paste0(Reduce(paste0, rep("#", 5), accumulate = TRUE), " title ", 1:5, "\n\n")
+  tmp_file <- local_rmd_file(h)
+  res <- render(tmp_file, github_document(html_preview = FALSE))
+  expect_snapshot_file(res, "github-atx.md", binary = FALSE)
+})
+
+

tests/testthat/test-lua-filters.R

@@ -1,14 +1,12 @@
 .generate_md_and_convert <- function(content, output_format) {
-  input_file <- tempfile(fileext = ".Rmd")
-  output_file <- tempfile()
-  on.exit(unlink(c(input_file, output_file)), add = TRUE)
-  xfun::write_utf8(c("---\ntitle: Test\n---\n", content), input_file)
+  input_file <- local_rmd_file(c("---\ntitle: Test\n---\n", content))
+  output_file <- withr::local_tempfile()
   res <- rmarkdown::render(input_file, output_format = output_format, output_file = output_file, quiet = TRUE)
   xfun::read_utf8(res)
 }
 
 # Lua filters exists only since pandoc 2.0
-skip_if_not(rmarkdown::pandoc_available("2.0"))
+skip_if_not_pandoc("2.0")
 
 test_that("pagebreak Lua filters works", {
   rmd <- "# HEADER 1\n\\newpage\n# HEADER 2\n\\pagebreak\n# HEADER 3"