node_modules/stylelint/lib/utils/isCustomPropertySet.js

/* @flow */
"use strict";

const _ = require("lodash");
const hasBlock = require("../utils/hasBlock");

/**
 * Check whether a Node is a custom property set
 */
module.exports = function(node /*: Object*/) /*: boolean*/ {
  const selector = _.get(node, "raws.selector.raw", node.selector);

  return (
    node.type === "rule" &&
    hasBlock(node) &&
    selector.slice(0, 2) === "--" &&
    selector.slice(-1) === ":"
  );
};