Support new Pandoc 3.4 behavior with GFM math (#2573)

DESCRIPTION

@@ -1,7 +1,7 @@
 Type: Package
 Package: rmarkdown
 Title: Dynamic Documents for R
-Version: 2.28.1
+Version: 2.28.2
 Authors@R: c(
  person("JJ", "Allaire", , "jj@posit.co", role = "aut"),
  person("Yihui", "Xie", , "xie@yihui.name", role = c("aut", "cre"), comment = c(ORCID = "0000-0003-0645-5666")),

R/github_document.R

@@ -102,8 +102,8 @@ github_document <- function(toc = FALSE,
  # don't activate math in Pandoc and pass it as is
  # https://github.blog/changelog/2022-05-19-render-mathematical-expressions-in-markdown/
  math <- NULL
- # TODO: Check for version - should be the default in Pandoc 2.19+
- variant <- paste0(variant, "+tex_math_dollars")
+ # Pandoc 3.4 uses +tex_math_gfm by default to write special gfm syntax. We choose to keep $$ and $ which are still supported by Github
+ variant <- if (pandoc_available("3.4")) paste0(variant, "-tex_math_gfm") else paste0(variant, "+tex_math_dollars")
  preview_math <- check_math_argument("mathjax")
  } else {
  # fallback to webtex

tests/testthat/test-github_document.R

@@ -13,7 +13,7 @@ test_that("toc has correct identifier", {
  } else {
  "before-pandoc-2.18"
  }
- res <- render(tmp_file, github_document(toc = TRUE, html_preview = FALSE))
+ res <- render(tmp_file, github_document(toc = TRUE, html_preview = FALSE), quiet = TRUE)
  expect_snapshot_file(res, "github-toc.md", compare = compare_file_text, variant = pandoc_version)
 })
 
@@ -32,7 +32,7 @@ test_that("toc has correct identifier also when sections are numbered ", {
  } else {
  "before-pandoc-2.18"
  }
- res <- render(tmp_file, github_document(toc = TRUE, number_sections = TRUE, html_preview = FALSE))
+ res <- render(tmp_file, github_document(toc = TRUE, number_sections = TRUE, html_preview = FALSE), quiet = TRUE)
  expect_snapshot_file(res, "github-toc-numbered.md", compare = compare_file_text, variant = pandoc_version)
 })
 
@@ -41,7 +41,7 @@ test_that("github_document produces atx-header", {
  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))
+ res <- render(tmp_file, github_document(html_preview = FALSE), quiet = TRUE)
  expect_snapshot_file(res, "github-atx.md", compare = compare_file_text)
 })