From 3950dcaa02e5cb0750e88ab1541166b0d471cfea Mon Sep 17 00:00:00 2001
From: Rowan Cockett <rowanc1@gmail.com>
Date: Mon, 6 Jan 2025 14:42:00 -0700
Subject: [PATCH] =?UTF-8?q?=E2=8C=A8=EF=B8=8F=20Do=20not=20export=20code?=
 =?UTF-8?q?=20block=20options=20when=20undefined=20(#1721)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Franklin Koch <franklinwkoch@gmail.com>
---
 .changeset/wicked-gifts-walk.md          |  5 +++++
 packages/myst-to-md/src/directives.ts    |  4 +++-
 packages/myst-to-md/tests/directives.yml | 20 ++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/wicked-gifts-walk.md

diff --git a/.changeset/wicked-gifts-walk.md b/.changeset/wicked-gifts-walk.md
new file mode 100644
index 000000000..7f317b6ec
--- /dev/null
+++ b/.changeset/wicked-gifts-walk.md
@@ -0,0 +1,5 @@
+---
+"myst-to-md": patch
+---
+
+Do not have code block options exported when they are null
diff --git a/packages/myst-to-md/src/directives.ts b/packages/myst-to-md/src/directives.ts
index d855d548d..93558289b 100644
--- a/packages/myst-to-md/src/directives.ts
+++ b/packages/myst-to-md/src/directives.ts
@@ -98,7 +98,9 @@ const CODE_BLOCK_KEYS = [
  * non-directive code fence.
  */
 function code(node: any, _: Parent, state: NestedState, info: Info): string {
-  const nodeCodeBlockKeys = Object.keys(node).filter((k) => CODE_BLOCK_KEYS.includes(k));
+  const nodeCodeBlockKeys = Object.entries(node).filter(
+    ([k, v]) => CODE_BLOCK_KEYS.includes(k) && v != null,
+  );
   if (!nodeCodeBlockKeys.length) {
     return defaultHandlers.code(node, _, state, info);
   }
diff --git a/packages/myst-to-md/tests/directives.yml b/packages/myst-to-md/tests/directives.yml
index 5ea4833c0..f56124b64 100644
--- a/packages/myst-to-md/tests/directives.yml
+++ b/packages/myst-to-md/tests/directives.yml
@@ -217,6 +217,26 @@ cases:
       :lineno-start: 2
       :meta: highlight-line="2"
 
+      5+5
+      print("hello world")
+       ```
+       ```
+      ````
+  - title: code directive - null options
+    mdast:
+      type: root
+      children:
+        - type: code
+          lang: python
+          meta: null
+          showLineNumbers: null
+          value: |-
+            5+5
+            print("hello world")
+             ```
+             ```
+    markdown: |-
+      ````python
       5+5
       print("hello world")
        ```