Roundtripping three empty lists results in a thematic break

[wooorm]

Subject of the issue

Your environment

n/a

Steps to reproduce

The following uncommon markdown is three empty lists/list items in each other.

+ * -

Expected behavior

🤷‍♂️

Actual behavior

Given that bullet is set to a value that can also be used for a thematic break (- or *), from-markdown will serialize as * * * or - - -, which is then parsed again as a thematic break.

[benwoodward]

What I just experienced is that --- is serialized as ***.

Code:

const mdSyntaxTree = markdownToMdAst(markdown);
console.log(toMarkdown(mdSyntaxTree));

function markdownToMdAst(markdown) {
  const mdAstTree = unified()
    .use(remarkParse)
    .parse(markdown)
  return mdAstTree;
}

Input:

one

---

two

Output:

[ChristianMurphy]

@benwoodward what you're describing is different, unrelated, and expected behavior. Both are thematic breaks https://astexplorer.net/#/gist/526a859153287c044491fa011ed08a14/c4ae05f5e409472ddf66386f216bf29a0681be4d

MDAST is an AST, not a CST. Meaning it will preserve structure, it was a thematic break before, it still is a thematic break, but it may not preserve the exact formatting as before (which a CST would).

[ChristianMurphy]

Another example related to this, lists with a thematic break inside also collapse into just a thematic break

- * **

[ChristianMurphy]

Another variation of this

-    -

-
    -    -

compiles to

*   *

*   *   *

which appears to trigger the issue again, even in latest

[wooorm]

Could you make this reproducible? Or is it literally this way in this projects tests? I’m hoping that this was already fixed, because the tests seem to indicate it: https://github.com/syntax-tree/mdast-util-to-markdown/commit/0148aa6e0318116cf5d2102cd8be28486be9d737.

[ChristianMurphy]

https://stackblitz.com/edit/node-dsbc65?file=index.js

[wooorm]

thanks! released too!