fix(markdown) strong/emphasis requires whitespace after

[joshgoebel]

Resolves #3519. Prevents false positive of emphasis when bullets are nested inside block quotes. This doesn't detect the bullets, it only fixes the false positive.

Checklist

• Added markup tests, or they don't apply here because...
• Updated the changelog at CHANGES.md

[allejo]

Gonna start a quick discussion on this one. I did some light reading on the commonmark spec and learned two things:

• newlines count as terminating the given bold/italic sequence
• we'd get false positives with __ too if there's a space after it

Given that any whitespace (including newlines) terminate the sequence, maybe use \s instead of [ ]. So I've got this snippet:

const BOLD = {
  className: 'strong',
  contains: [], // defined later
  variants: [
    {
      begin: /_{2}(?!\s)/, // <- changed
      end: /_{2}/
    },
    {
      begin: /\*{2}(?!\s)/, // <- changed
      end: /\*{2}/
    }
  ]
};
const ITALIC = {
  className: 'emphasis',
  contains: [], // defined later
  variants: [
    {
      begin: /\*(?![*\s])/, // <- changed
      end: /\*/
    },
    {
      begin: /_(?![_\s])/, // <- changed
      end: /_/,
      relevance: 0
    }
  ]
};

(I'd submit it as a review but GitHub doesn't let me make changes on non-touched lines)

This PR as-is would result in the following,

[allejo]

The markdown I'm using:

** i shouldn't be italic**

* and I shouldn't be italic either*

__ not really bold__

_ not italic_

Hello

**actually bold**

__again, bold__

*italic*
_oh i'm italic_

How GitHub renders this

---

** i shouldn't be italic**

• and I shouldn't be italic either*

__ not really bold__

_ not italic_

Hello

actually bold

again, bold

italic
oh i'm italic

[double-beep]

• newlines count as terminating the given bold/italic sequence

Not completely accurate:

**not bold
**

*not italic
*

**should be
bold**

*should be
italic*

---

**not bold
**

*not italic
*

should be
bold

should be
italic

[joshgoebel]

So I've got this snippet:

Did you try and see if all the tests still passed with that snippet?

[allejo]

So I've got this snippet:

Did you try and see if all the tests still passed with that snippet?

Ran it against npm run build_and_test and just got an auto-detect failure (but I think that's due to my Node version; this happens on main for me too).

  1720 passing (14s)
  3 pending
  1 failing

  1) hljs.highlightAuto()
       should be detected as sfz:

      AssertionError: sample.txt should be detected as sfz, but was gradle
      + expected - actual

      -gradle
      +sfz

---

Not completely accurate:

**not bold
**

*not italic
*

**should be
bold**

*should be
italic*

Ahhh good catch on this, you're right. Anything that's not "punctuation" before the closing sequence keeps it bold/italic. But if it's just a newline and closing, then it's not valid since the newline is considered "punctuation"

[allejo]

I don't mean to overstep and push to your branch, @joshgoebel! I'd like to vote that we fix the immediate false positives by disallowing newlines inside of bolds and italics. And in the future, come up with a more robust expression that matches the markdown spec and can handle newlines (or whatever new APIs that may be added).