docs: add jest-puppeteer example

docs/Puppeteer.md

@@ -0,0 +1,112 @@
+---
+id: puppeteer
+title: Using with puppeteer
+---
+
+With the
+[Global Setup/Teardown](https://facebook.github.io/jest/docs/en/configuration.html#globalsetup-string)
+and
+[Async Test Environment](https://facebook.github.io/jest/docs/en/configuration.html#testenvironment-string)
+APIs, Jest can work smoothly with
+[puppeteer](https://github.com/GoogleChrome/puppeteer).
+
+## A jest-puppeteer example
+
+The basic idea is to:
+
+1. launch & file the websocket endpoint of puppeteer with Global Setup
+2. connect to puppeteer from each Test Environment
+3. close puppeteer with Global Teardown
+
+Here's an example of the GlobalSetup script
+
+```js
+// setup.js
+module.exports = function() {
+  return new Promise((resolve, reject) => {
+    puppeteer.launch().then(browser => {
+      // store the browser instance so we can teardown it later
+      global.__BROWSER__ = browser;
+
+      // file the wsEndpoint for TestEnvironments
+      mkdirp.sync(DIR);
+      fs.writeFileSync(path.join(DIR, 'wsEndpoint'), browser.wsEndpoint());
+      resolve();
+    });
+  });
+};
+```
+
+Then we need a custom Test Environment for puppeteer
+
+```js
+// puppeteer_environment.js
+class PuppeteerEnvironment extends NodeEnvironment {
+  constructor(config) {
+    super(config);
+  }
+
+  async setup() {
+    await super.setup();
+    // get the wsEndpoint
+    const wsEndpoint = fs.readFileSync(path.join(DIR, 'wsEndpoint'), 'utf8');
+    if (!wsEndpoint) {
+      throw new Error('wsEndpoint not found');
+    }
+
+    // connect to puppeteer
+    this.global.__BROWSER__ = await puppeteer.connect({
+      browserWSEndpoint: wsEndpoint,
+    });
+  }
+
+  async teardown() {
+    await super.teardown();
+  }
+
+  runScript(script) {
+    return super.runScript(script);
+  }
+}
+```
+
+Finally we can close the puppeteer instance and clean-up the file
+
+```js
+// teardown.js
+module.exports = function() {
+  return new Promise((resolve, reject) => {
+    // close the browser instance
+    global.__BROWSER__.close();
+
+    // clean-up the wsEndpoint file
+    rimraf.sync(DIR);
+    resolve();
+  });
+};
+```
+
+With all the things set up, we can now write our tests like this:
+
+```js
+// test.js
+describe(
+  '/ (Home Page)',
+  () => {
+    let page;
+    beforeAll(async () => {
+      page = await global.__BROWSER__.newPage();
+      await page.goto('https://google.com');
+    }, timeout);
+
+    it('should load without error', async () => {
+      let text = await page.evaluate(() => document.body.textContent);
+      expect(text).toContain('google');
+    });
+  },
+  timeout,
+);
+```
+
+Here's the code of
+[full working example](https://github.com/xfumihiro/jest-puppeteer-example).

website/sidebars.json

@@ -27,6 +27,7 @@
       "timer-mocks",
       "manual-mocks",
       "webpack",
+      "puppeteer",
       "migration-guide",
       "troubleshooting"
     ]