JSDOM: Could not parse CSS stylesheet

Question

With the following command:

./node_modules/babel-core/register.js ./node_modules/jsdom-global/register.js **/*_spec.jsx

I am running the following test file:

"use strict";

import React from 'react';
import {expect} from 'chai';
import Enzyme from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
import {Home} from '../../../src/home/home.jsx';

Enzyme.configure({adapter: new Adapter()});

describe('<Home />', () => {
    const setup = () => {
        const props = {
            isButtonOn: true,
            toggleButton: () => null,
        };
        return Enzyme.shallow(<Home {...props}/>);
    };

    it('should a title and a button', () => {
        const wrapper = setup();
        expect(wrapper.find('.title').length).to.equal(1);
        expect(wrapper.find('button').length).to.equal(1);
    });
});

Which tests the following component:

"use strict";

import React from 'react';
import PropTypes from 'prop-types';
import {connect} from 'react-redux';
import {toggleButton} from '../store/home/actions.js';
import swal from 'sweetalert2';

export class Home extends React.Component {
    constructor() {
        super();
        this._toggleButton = this._toggleButton.bind(this);
    }

    _toggleButton() {
        // Invoke swal() here
    }

    render() {
        return (
            <div className="home">
                <div className="title">
                    <u>Frontend Template</u>
                </div>
                <div>
                    <button onClick={this._toggleButton}/>
                </div>
            </div>
        );
    }
}

However, even if the test cases fail, I get the following error message as well as (omitted below) the contents of the css file that cannot be parsed:

Error: Could not parse CSS stylesheet
    at exports.createStylesheet (/home/jbunker/IdeaProjects/frontend-template/node_modules/jsdom/lib/jsdom/living/helpers/stylesheets.js:35:21)
    at HTMLStyleElementImpl._updateAStyleBlock (/home/jbunker/IdeaProjects/frontend-template/node_modules/jsdom/lib/jsdom/living/nodes/HTMLStyleElement-impl.js:68:5)
    at HTMLStyleElementImpl._childTextContentChangeSteps (/home/jbunker/IdeaProjects/frontend-template/node_modules/jsdom/lib/jsdom/living/nodes/HTMLStyleElement-impl.js:37:12)
    at HTMLStyleElementImpl.insertBefore (/home/jbunker/IdeaProjects/frontend-template/node_modules/jsdom/lib/jsdom/living/nodes/Node-impl.js:225:14)
    at HTMLStyleElementImpl.appendChild (/home/jbunker/IdeaProjects/frontend-template/node_modules/jsdom/lib/jsdom/living/nodes/Node-impl.js:327:17)
    at HTMLStyleElement.appendChild (/home/jbunker/IdeaProjects/frontend-template/node_modules/jsdom/lib/jsdom/living/generated/Node.js:192:45)
    at injectCSS (/home/jbunker/IdeaProjects/frontend-template/node_modules/sweetalert2/dist/sweetalert2.all.js:2053:11)
    at /home/jbunker/IdeaProjects/frontend-template/node_modules/sweetalert2/dist/sweetalert2.all.js:2057:1
    at styles (/home/jbunker/IdeaProjects/frontend-template/node_modules/sweetalert2/dist/sweetalert2.all.js:6:82)
    at Object.<anonymous> (/home/jbunker/IdeaProjects/frontend-template/node_modules/sweetalert2/dist/sweetalert2.all.js:9:2)
    at Module._compile (module.js:569:30)
    at Module._extensions..js (module.js:580:10)
    at Object.require.extensions.(anonymous function) [as .js] (/home/jbunker/IdeaProjects/frontend-template/node_modules/babel-register/lib/node.js:152:7)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Module.require (module.js:513:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/home/jbunker/IdeaProjects/frontend-template/src/home/home.jsx:7:1)
    at Module._compile (module.js:569:30)
    at loader (/home/jbunker/IdeaProjects/frontend-template/node_modules/babel-register/lib/node.js:144:5)
    at Object.require.extensions.(anonymous function) [as .jsx] (/home/jbunker/IdeaProjects/frontend-template/node_modules/babel-register/lib/node.js:154:7)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Module.require (module.js:513:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/home/jbunker/IdeaProjects/frontend-template/test/test_react/home/home_spec.jsx:7:1)
    at Module._compile (module.js:569:30)
    at loader (/home/jbunker/IdeaProjects/frontend-template/node_modules/babel-register/lib/node.js:144:5)
    at Object.require.extensions.(anonymous function) [as .jsx] (/home/jbunker/IdeaProjects/frontend-template/node_modules/babel-register/lib/node.js:154:7)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Module.require (module.js:513:17)
    at require (internal/module.js:11:18)
    at /home/jbunker/IdeaProjects/frontend-template/node_modules/mocha/lib/mocha.js:231:27
    at Array.forEach (native)
    at Mocha.loadFiles (/home/jbunker/IdeaProjects/frontend-template/node_modules/mocha/lib/mocha.js:228:14)
    at Mocha.run (/home/jbunker/IdeaProjects/frontend-template/node_modules/mocha/lib/mocha.js:536:10)
    at Object.<anonymous> (/home/jbunker/IdeaProjects/frontend-template/node_modules/mocha/bin/_mocha:582:18)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3

When I remove the following line from my component:

import swal from 'sweetalert2';

The error message disappears. This leads me to believe that the css used in sweetalert2 is not properly being parsed by JSDOM. A potential solution seems to be to use virtual consoles:

const virtualConsole = new jsdom.VirtualConsole();
const dom = new JSDOM(``, { virtualConsole });

or to send to a console while omitting errors:

virtualConsole.sendTo(console, {omitJSDOMErrors: true});

However, I have not had success with these approaches.

What can I do to avoid polluting my console with this error?

EDIT: I was able to solve this by placing my JSDOM logic in a separate file:

"use strict";

process.env.NODE_ENV = 'test';

require('babel-register')();

const jsdom = require('jsdom');
const {JSDOM} = jsdom;
const virtualConsole = new jsdom.VirtualConsole();
const dom = new JSDOM('<!DOCTYPE html><html><head></head><body></body></html>', {virtualConsole});

global.document = dom.window.document;
global.window = dom.window.document.defaultView;
global.navigator = {userAgent: 'node.js'};
global.requestAnimationFrame = () => null;

const exposedProperties = ['window', 'navigator', 'document'];
Object.keys(document.defaultView).forEach((property) => {
    if (typeof global[property] === 'undefined') {
        exposedProperties.push(property);
        global[property] = document.defaultView[property];
    }
});

Then, I added the following line in my package.json under scripts:

"test": "mocha --reporter progress tools/testSetup.js \"**/*_spec.jsx\""

By running npm test, I get the test results without any console pollution.

dcio · Accepted Answer · 2020-10-12 17:21:06Z

4

As @JKB mentioned, using this code fixes the error.

const virtualConsole = new jsdom.VirtualConsole();
const dom = new JSDOM(``, { virtualConsole });

edited Oct 12, 2020 at 17:21

dcio

2,3126 gold badges34 silver badges51 bronze badges

answered Oct 12, 2020 at 13:41

Mukesh Kumar Sah

811 silver badge7 bronze badges

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Comments

Tom · Accepted Answer · 2021-07-01 17:34:30Z

1

I can indeed confirm that using that code helped and fixed it. Basically, I stop seeing the error on my console.

const fs = require("fs");
const got = require("got");
const jsdom = require("jsdom");
const { JSDOM } = jsdom;

async function newsCatcher(option) {
  const virtualConsole = new jsdom.VirtualConsole();
  const website = 'website here';

  const TEST = await got(website)
  .then((response) => {
    const dom = new JSDOM(response.body, {virtualConsole});
    const info = Array.from(
      dom.window.document.querySelectorAll(
        "li.stack__slice__item > article > div.card__inner > div.card__content > div > h3 > a"
      )
    )
    .map((e) => e.innerHTML);
    return info
  })
  .catch((err) => {
    console.log(err);
  });
}

edited Jul 1, 2021 at 17:34

Tom

9,2087 gold badges56 silver badges85 bronze badges

answered May 19, 2021 at 10:33

Pedro Leite

211 silver badge6 bronze badges

2 Comments

Saikat Saha Over a year ago

please be more descriotive

Pedro Leite Over a year ago

What do you mean? I was replying to the person. Stating that indeed that workaround worked and my code,

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