Bugfix/issue 4034 (#4116)

* cellcleanup filter

* add cellcleanup to chain

* add filter to cleanup empty cell. Closes #4034

* changelog

Author: cscheid

news/changelog-1.3.md

@@ -118,6 +118,7 @@
 - Support parsing markdown in table captions in LaTeX and HTML tables ([#2573](https://github.com/quarto-dev/quarto-cli/issues/2573)).
 - Improve parsing of include shortcodes ([#3159](https://github.com/quarto-dev/quarto-cli/issues/3159)).
 - Add support for Youtube privacy-enhanced urls in `video` shortcodes ([#4060](https://github.com/quarto-dev/quarto-cli/issues/4060)).
+- Don't emit empty cells ([#4034](https://github.com/quarto-dev/quarto-cli/issues/4034)).
 
 ## Pandoc filter changes
 

src/command/render/pandoc.ts

@@ -970,6 +970,11 @@ export async function runPandoc(
   delete pandocPassedMetadata.format;
   delete pandocPassedMetadata.project;
   delete pandocPassedMetadata.website;
+  if (pandocPassedMetadata._quarto) {
+    // these shouldn't be visible because they are emitted on markdown output
+    // and it breaks ensureFileRegexMatches
+    delete pandocPassedMetadata._quarto.tests;
+  }
 
   Deno.writeTextFileSync(
     metadataTemp,

src/resources/filters/main.lua

@@ -73,6 +73,7 @@ import("./quarto-post/responsive.lua")
 import("./quarto-post/reveal.lua")
 import("./quarto-post/tikz.lua")
 import("./quarto-post/pdf-images.lua")
+import("./quarto-post/cellcleanup.lua")
 
 import("./quarto-finalize/dependencies.lua")
 import("./quarto-finalize/book-cleanup.lua")
@@ -219,6 +220,7 @@ local quartoPre = {
 
 local quartoPost = {
   -- quarto-post
+  { name = "post-cell-cleanup", filter = cell_cleanup() },
   { name = "post-cites", filter = indexCites() },
   { name = "post-foldCode", filter = foldCode() },
   { name = "post-figureCleanupCombined", filter = combineFilters({

src/resources/filters/quarto-post/cellcleanup.lua

@@ -0,0 +1,14 @@
+-- cellcleanup.lua
+-- Copyright (C) 2020-2023 Posit Software, PBC
+
+function cell_cleanup()
+  return {
+    Div = function(div)
+      if (#div.classes == 1 and 
+          div.classes[1] == "cell" and
+          #div.content == 0) then
+        return {}
+      end
+    end
+  }
+end

tests/docs/smoke-all/2023/01/26/4034.qmd

@@ -0,0 +1,19 @@
+---
+title: "4034"
+format: markdown
+_quarto:
+  tests:
+    markdown:
+      ensureFileRegexMatches:
+        - []
+        - [".cell"]
+---
+
+```{r}
+#| echo: false
+#| warning: false
+#| message: false
+#| output: false
+z=3+4
+z
+```

tests/utils.ts

@@ -29,7 +29,7 @@ export function outputForInput(input: string, to: string) {
   if (baseFormat === "revealjs") {
     outputExt = "html";
   }
-  if (baseFormat === "commonmark" || baseFormat === "gfm") {
+  if (["commonmark", "gfm", "markdown"].some((f) => f === baseFormat)) {
     outputExt = "md";
   }
   if (baseFormat === "csljson") {