links-in-buttons-gatherer.js

"use strict";

const Gatherer = require("lighthouse").Gatherer;

class LinksInButtons extends Gatherer {
  async afterPass(options) {
    const driver = options.driver;
    const expression = `(function() {
        return document.querySelectorAll("button a").length === 0;
    })()`;
    return await driver.evaluateAsync(expression);
  }
}

module.exports = LinksInButtons;

If we were writing this audit we would probably return some basic info about all the links in the buttons, and then the audit would fail if the artifact had length > 0. The nice thing about this approach of splitting audit/gatherer is that the audit then has some helpful debug information to show when it's failing, i.e. you can give the textContent/url of the link that's failing so the dev knows where to go to fix it.