setupTests.js

import Enzyme from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
import { JSDOM } from 'jsdom';

// React 16 Enzyme adapter
Enzyme.configure({ adapter: new Adapter() });

// Ignore `.styl` files
require.extensions['.styl'] = () => {
    return;
};

// JSDOM
const jsdom = new JSDOM('<!doctype html><html><body></body></html>');
const { window } = jsdom;

const copyProps = (src, target) => {
    const props = Object.getOwnPropertyNames(src)
        .filter(prop => typeof target[prop] === 'undefined')
        .reduce((result, prop) => ({
            ...result,
            [prop]: Object.getOwnPropertyDescriptor(src, prop)
        }), {});
    Object.defineProperties(target, props);
};

global.window = window;
global.document = window.document;
global.navigator = {
    userAgent: 'node.js'
};

copyProps(window, global);