feat(learn): lazy load Enzyme in the test frame

client/src/client/frame-runner.js

@@ -9,7 +9,10 @@ if (window.frameElement && window.frameElement.id === testId) {
   document.addEventListener('DOMContentLoaded', initTestFrame);
 }
 
-function initTestFrame() {
+// For tests in CI.
+document.__initTestFrame = initTestFrame;
+
+async function initTestFrame() {
   const code = (document.__source || '').slice(0);
   if (!document.__getUserInput) {
     document.__getUserInput = () => code;
@@ -38,8 +41,16 @@ function initTestFrame() {
   const assert = chai.assert;
   /* eslint-enable no-unused-vars */
 
-  if (document.Enzyme) {
+  let Enzyme;
-    window.Enzyme = document.Enzyme;
+  if (document.__loadEnzyme) {
+    let Adapter16;
+    /* eslint-disable no-inline-comments */
+    [{ default: Enzyme }, { default: Adapter16 }] = await Promise.all([
+      import(/* webpackChunkName: "enzyme" */ 'enzyme'),
+      import(/* webpackChunkName: "enzyme-adapter" */ 'enzyme-adapter-react-16')
+    ]);
+    /* eslint-enable no-inline-comments */
+    Enzyme.configure({ adapter: new Adapter16() });
   }
 
   document.__runTest = async function runTests(testString) {

client/src/templates/Challenges/redux/execute-challenge-saga.js

@@ -112,6 +112,7 @@ function* executeDOMChallengeSaga(proxyLogger) {
   const meta = yield select(challengeMetaSelector);
   const document = yield getContext('document');
   const ctx = yield call(buildDOMChallenge, files, meta);
+  ctx.loadEnzyme = Object.keys(files).some(key => files[key].ext === 'jsx');
   yield call(createTestFrame, document, ctx, proxyLogger);
   // wait for a code execution on a "ready" event in jQuery challenges
   yield delay(100);

client/src/templates/Challenges/utils/frame.js

@@ -1,7 +1,4 @@
 import { toString, flow } from 'lodash';
-import { configure, shallow, mount } from 'enzyme';
-import Adapter16 from 'enzyme-adapter-react-16';
-import { setConfig } from 'react-hot-loader';
 
 // we use two different frames to make them all essentially pure functions
 // main iframe is responsible rendering the preview and is where we proxy the
@@ -33,17 +30,10 @@ const createHeader = (id = mainId) => `
 
 export const runTestInTestFrame = async function(document, test, timeout) {
   const { contentDocument: frame } = document.getElementById(testId);
-  // Enable Stateless Functional Component. Otherwise, enzyme-adapter-react-16
-  // does not work correctly.
-  setConfig({ pureSFC: true });
-  try {
   return await Promise.race([
     new Promise((_, reject) => setTimeout(() => reject('timeout'), timeout)),
     frame.__runTest(test)
   ]);
-  } finally {
-    setConfig({ pureSFC: false });
-  }
 };
 
 const createFrame = (document, id) => ctx => {
@@ -83,18 +73,14 @@ const buildProxyConsole = proxyLogger => ctx => {
 };
 
 const writeTestDepsToDocument = frameReady => ctx => {
-  const { sources } = ctx;
+  const { sources, loadEnzyme } = ctx;
-  // add enzyme
-  // TODO: do programatically
-  // TODO: webpack lazyload this
-  configure({ adapter: new Adapter16() });
-  ctx.document.Enzyme = { shallow, mount };
   // default for classic challenges
   // should not be used for modern
   ctx.document.__source = sources && 'index' in sources ? sources['index'] : '';
   // provide the file name and get the original source
   ctx.document.__getUserInput = fileName => toString(sources[fileName]);
   ctx.document.__frameReady = frameReady;
+  ctx.document.__loadEnzyme = loadEnzyme;
   return ctx;
 };
 

client/webpack-frame-runner.js

@@ -11,6 +11,8 @@ module.exports = (env = {}) => {
     },
     devtool: __DEV__ ? 'inline-source-map' : 'source-map',
     output: {
+      publicPath: '/js/',
+      chunkFilename: '[name].js',
       path: path.join(__dirname, './static/js')
     },
     stats: {
@@ -32,7 +34,10 @@ module.exports = (env = {}) => {
                   { modules: false, targets: '> 0.25%, not dead' }
                 ]
               ],
-              plugins: ['@babel/plugin-transform-runtime']
+              plugins: [
+                '@babel/plugin-transform-runtime',
+                '@babel/plugin-syntax-dynamic-import'
+              ]
             }
           }
         }