Upgrade Jest and Webpack

Mostly based on changes made in the original NHS app: nhsuk/cookie-consent@ed071c0

cookie-test-environment.js

@@ -1,13 +1,14 @@
-const JSDOMEnvironment = require('jest-environment-jsdom');
+import JSDOMEnvironment from 'jest-environment-jsdom';
 
-module.exports = class CookieTestEnvironment extends JSDOMEnvironment {
-  constructor(config) {
-    super(config);
+export default class CookieTestEnvironment extends JSDOMEnvironment {
+  constructor(config, options) {
+    super(config, options);
+    this.global.jsdom = this.dom;
     this.global.cookieJar = this.dom.cookieJar;
   }
 
   teardown() {
     this.global.jsdom = null;
     return super.teardown();
   }
-};
+}

jest.config.js

@@ -10,10 +10,8 @@ module.exports = {
   testEnvironment: './cookie-test-environment.js',
   testEnvironmentOptions: {
     cookieJar: new jsdom.CookieJar(),
+    // Set a url with a path so we can write cookie tests that use paths.
+    url: 'http://localhost/path1/path2/path3/',
   },
-  testMatch: [
-    '<rootDir>/src/*.test.js',
-  ],
-  // Set a url with a path so we can write cookie tests that use paths.
-  testURL: 'http://localhost/path1/path2/path3/',
+  testMatch: ['<rootDir>/src/*.test.js'],
 };