Fix false positives for variables in font-family-no-missing-generic-family-keyword

[jeddy3]

Clearly describe the bug

There are false positives in font-family-no-missing-generic-family-keyword if I use a variable and a font family.

Demo.

See #3848 (comment).

Which rule, if any, is the bug related to?

font-family-no-missing-generic-family-keyword

What code is needed to reproduce the bug?

a {
  font-family: 'font', var(--font);
}

What stylelint configuration is needed to reproduce the bug?

{
  "rules": {
     "font-family-no-missing-generic-family-keyword": [true, 
       { "ignoreFontFamilies": ["var(--font)"] }
     ]
  }
}

Which version of stylelint are you using?

13.3.0

How are you running stylelint: CLI, PostCSS plugin, Node.js API?

Demo

Does the bug relate to non-standard syntax (e.g. SCSS, Less etc.)?

No

What did you expect to happen?

No warnings to be flagged because the rule should ignore values that contain variables.

What actually happened (e.g. what warnings or errors did you get)?

The following warnings were flagged:

3:16 error Unexpected missing generic font family (font-family-no-missing-generic-family-keyword)

[jeddy3]

I've labelled the issue as ready to implement. Please consider contributing if you have time.

There are steps on how to fix a bug in a rule in the Developer guide.

[lensbart]

The same issue still persists with Sass variables (e.g. font-family: 'Comic Sans', $fontFamilyUI;). I’ve tried several permutations in the ignoreFontFamilies array: using a string, regex with escaped $ character, string-of-regex with twice-escaped \\, etc; but nothing seems to work.

// stylelint.config.js
module.exports = {
  rules: {
    'font-family-no-missing-generic-family-keyword': [
      true,
      { ignoreFontFamilies: [/\$fontFamilyUI/] }
    ]
  }
}

[ybiquitous]

@lensbart Thanks for the report. We can reproduce it on the demo.

[ybiquitous]

I've opened a new PR #5240!