stylelint-scss/src/rules/selector-no-redundant-nesting-selector/index.js

A collection of SCSS specific rules for stylelint

import { utils } from "stylelint"
import { namespace } from "../../utils"

export const ruleName = namespace("selector-no-redundant-nesting-selector")

export const messages = utils.ruleMessages(ruleName, {
  rejected: "Unnecessary nesting selector (&)",
})

export default function (actual) {
  return function (root, result) {
    const validOptions = utils.validateOptions(result, ruleName, { actual })
    if (!validOptions) { return }

    root.walkRules(/&/, rule => {
      const { selector } = rule
      // "Ampersand followed by a combinator followed by non-combinator non-ampersand and not the selector end"
      const regex = /^&\s*[>+~ ]\s*[^>+~ {&]+/

      if (selector === "&" || regex.test(selector)) {
        utils.report({
          ruleName,
          result,
          node: rule,
          message: messages.rejected,
        })
      }
    })
  }
}