test/helpers/setup-test-env.js

const { JSDOM } = require('jsdom');

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

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

global.window = window;
global.document = window.document;
global.navigator = {
      userAgent: 'node.js',
};
copyProps(window, global);