Add ignoreFunctions: [] to value-keyword-case

[FollowingFawn]

Clearly describe the bug

I am using stylelint and I have a several different custom color variables used in several properties such as border, background, color [using a non-standard t function].

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

value-keyword-case

What code is needed to reproduce the bug?

e.g.

a {
  border: 1px solid t(lightGray);
  background-color: t(lightBlue);
  color: var(--lightBlue);
}

What stylelint configuration is needed to reproduce the bug?

e.g.

{
  "rules": {
       "value-keyword-case": ["lower", {"ignoreKeywords": ["/^t(*)/"]}],
  }
}

Which version of stylelint are you using?

13.2.1

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

"force-app/main/default/**/*.css": [
  "stylelint --fix"
]

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

No

What did you expect to happen?

I want to either ignore any custom variable inside t() or var(--) or allow camelCasing.

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

e.g. "The following warnings were flagged:"

Expected "digitalBlue" to be "digitalblue"   value-keyword-case    

Is there a way to either ignore camelCasing or ignore anything within t() or var(--)?, e.g.

"value-keyword-case": ["lower", {"ignoreKeywords": ["/^t(*)/"]}]

[jeddy3]

@FollowingFawn Thanks for the report and for using the template.

Is there a way to either ignore camelCasing or ignore anything within t() or var(--)?

Keywords within var functions are already ignored by the rule.

Given:

a {
  color: var(--camelCase);
  color: t(--camelCase);
}

We get:

3:12 error Expected "--camelCase" to be "--camelcase" (value-keyword-case)

As only the second declaration is reported as a violation. See this demo.

Keywords within t functions aren't ignored because t is a non-standard function. I recommend you only use var for variables. However, if this is not possible for some reason, we can add an ignoreFunctions optional secondary option to the rule:

{
  "rules": {
       "value-keyword-case": ["lower", {"ignoreFunctions": ["t"]}],
  }
}

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

There are steps on how to add a new option in the Developer guide.

[mattxwang]

Just submitted a PR for this feature! #4733