fix purgecss-from-pug not handle class attributes with multiple values correctly #677

[Nauja]

Proposed changes

Replace token.val in purgecss-from-pug by ...token.val.split(" ") as done in purgecss-from-html to correctly handle class attributes with multiple values.

      case "tag":
      case "id":
      case "class":
-       selectors.push(token.val);
+       selectors.push(...token.val.split(" "));
        break;
      case "attribute":
        if (token.name === "class" || token.name === "id") {
          selectors.push(
-           token.mustEscape ? token.val.replace(/"/g, "") : token.val
+           ...(token.mustEscape ? token.val.replace(/"/g, "") : token.val).split(" ")
          );
        }
        break;

Also complete the unittest for purgecss-from-pug to demonstrate that multiple classes are correctly handled.

See bug #677

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

I am fairly new to purgecss, but clearly all CSS classes are not correctly extracted from .pug files and this is related to purgecss-from-pug treating a class attribute with multiple values as a single value as shown in the bug report. When checking the difference with purgecss-from-html, we can see that purgecss-from-pug extract classes with token.val while purgecss-from-html do something like val.split(" ").

[Ffloriel]

Thanks!