chore: upgrade to Mocha v8 (#5997)

* chore: upgrade to Mocha v8

Mocha v8 has some nice improvements and also unlocks the potential
to have parallel test runs which may speed up CI.

mocha-config/puppeteer-unit-tests.js

@@ -18,9 +18,10 @@ const base = require('./base');
 
 module.exports = {
   ...base,
-  file: ['./test/mocha-utils.js'],
+  require: ['./test/mocha-utils.js'],
   spec: 'test/*.spec.js',
+  parallel: process.env.CI && !process.env.COVERAGE,
   // retry twice more, so we run each test up to 3 times if needed.
-  retries: 2,
+  retries: process.env.CI ? 2 : 0,
   timeout: 25 * 1000,
 };

package.json

@@ -84,7 +84,7 @@
     "expect": "^25.2.7",
     "jpeg-js": "^0.3.7",
     "minimist": "^1.2.0",
-    "mocha": "^7.1.1",
+    "mocha": "^8.0.1",
     "ncp": "^2.0.0",
     "pixelmatch": "^4.0.2",
     "pngjs": "^5.0.0",

test/coverage-utils.js

@@ -102,16 +102,17 @@ const trackCoverage = () => {
   clearOldCoverage();
   const coverageMap = new Map();
 
-  before(() => {
+  return {
+    beforeAll: () => {
       const api = require('../lib/api');
       const events = require('../lib/common/Events');
       for (const [className, classType] of Object.entries(api))
         traceAPICoverage(coverageMap, events, className, classType);
-  });
+    },
-
+    afterAll: () => {
-  after(() => {
       writeCoverage(coverageMap);
-  });
+    },
+  };
 };
 
 module.exports = {

test/mocha-utils.js

@@ -140,7 +140,14 @@ global.describeChromeOnly = (...args) => {
   if (isChrome) return describe(...args);
 };
 
-if (process.env.COVERAGE) trackCoverage();
+let coverageHooks = {
+  beforeAll: () => {},
+  afterAll: () => {},
+};
+
+if (process.env.COVERAGE) {
+  coverageHooks = trackCoverage();
+}
 
 console.log(
   `Running unit tests with:
@@ -176,7 +183,9 @@ exports.setupTestPageAndContextHooks = () => {
   });
 };
 
-before(async () => {
+exports.mochaHooks = {
+  beforeAll: [
+    async () => {
       const { server, httpsServer } = await setupServer();
 
       state.puppeteer = puppeteer;
@@ -187,20 +196,26 @@ before(async () => {
       state.isChrome = isChrome;
       state.isHeadless = isHeadless;
       state.puppeteerPath = path.resolve(path.join(__dirname, '..'));
-});
+    },
+    coverageHooks.beforeAll,
+  ],
 
-beforeEach(async () => {
+  beforeEach: async () => {
     state.server.reset();
     state.httpsServer.reset();
-});
+  },
 
-after(async () => {
+  afterAll: [
+    async () => {
       await state.server.stop();
       state.server = null;
       await state.httpsServer.stop();
       state.httpsServer = null;
-});
+    },
+    coverageHooks.afterAll,
+  ],
 
-afterEach(() => {
+  afterEach: () => {
     sinon.restore();
-});
+  },
+};