@puppeteer/replay

API | Contributing

> Puppeteer Replay is a library that provides an API to replay and stringify recordings created using Chrome DevTools Recorder

Installation

npm install @puppeteer/replay --save

If you want to replay recordings using Puppeteer, install Puppeteer as well:

npm install puppeteer --save

Getting started with Puppeteer Replay

You can use Puppeteer Replay to:

1. Replay recording. Replay recording with CLI or using the replay lib API.
2. Customize replay. Customize how a recording is run. For example, capture screenshots after each step or integrate with 3rd party libraries.
3. Transform recording. Customize how a recording is stringified. For example, transform the recording into another format.

Also, you can use third-party integrations that build on top of @puppeteer/replay, which includes:

Transform JSON user flows to custom scripts:

• Cypress Chrome Recorder. You can use it to convert user flow JSON files to Cypress test scripts. Watch this demo to see it in action.
• Nightwatch Chrome Recorder. You can use it to convert user flow JSON files to Nightwatch test scripts.
• WebdriverIO Chrome Recorder. You can use it to convert user flow JSON files to WebdriverIO test scripts.

Replay JSON user flows:

• Replay with TestCafe. You can use TestCafe to replay user flow JSON files and generate test reports for these recordings.
• Replay with Sauce Labs. You can replay the JSON files on Sauce Labs using saucectl.

1. Replay recording

Download this example recording and save it as recording.json.

Using CLI + npx:

npx @puppeteer/replay recording.json

Using CLI + package.json:

In your package.json add a new script to invoke the replay command:

{
  "scripts": {
    "replay": "replay recording.json"
  }
}

You can also give folder name as a parameter to run all the files in a folder.

Using CLI + npx:

npx @puppeteer/replay all-recordings # runs all recordings in the "all-recordings" folder.

Using CLI + package.json:

{
  "scripts": {
    "replay": "replay all-recordings"
  }
}

Set the PUPPETEER_HEADLESS environment variable or --headless CLI flag to control whether the browser is started in a headful or headless mode. For example,

PUPPETEER_HEADLESS=true npx @puppeteer/replay recording.json # runs in headless mode, the default mode.
PUPPETEER_HEADLESS=false npx @puppeteer/replay recording.json # runs in headful mode.
PUPPETEER_HEADLESS=chrome npx @puppeteer/replay recording.json # runs in the new experimental headless mode.

Use the --extension CLI flag to provide a custom replay extension for running the recording. For example,

npx @puppeteer/replay --extension examples/cli-extension/extension.js recording.json

Run npx @puppeteer/replay --help to see all CLI options.

Using the replay lib API:

import { createRunner, parse } from '@puppeteer/replay';
import fs from 'fs';

// Read recording for a file.
const recordingText = fs.readFileSync('./recording.json', 'utf8');
// Validate & parse the file.
const recording = parse(JSON.parse(recordingText));
// Create a runner and execute the script.
const runner = await createRunner(recording);
await runner.run();

2. Customize replay

The library offers a way to customize how a recording is run. You can extend the PuppeteerRunnerExtension class as shown in the example below.

Full example of the PuppeteerRunnerExtension: link

import { createRunner, PuppeteerRunnerExtension } from '@puppeteer/replay';
import puppeteer from 'puppeteer';

const browser = await puppeteer.launch({
  headless: true,
});

const page = await browser.newPage();

class Extension extends PuppeteerRunnerExtension {
  async beforeAllSteps(flow) {
    await super.beforeAllSteps(flow);
    console.log('starting');
  }

  async beforeEachStep(step, flow) {
    await super.beforeEachStep(step, flow);
    console.log('before', step);
  }

  async afterEachStep(step, flow) {
    await super.afterEachStep(step, flow);
    console.log('after', step);
  }

  async afterAllSteps(flow) {
    await super.afterAllSteps(flow);
    console.log('done');
  }
}

const runner = await createRunner(
  {
    title: 'Test recording',
    steps: [
      {
        type: 'navigate',
        url: 'https://wikipedia.org',
      },
    ],
  },
  new Extension(browser, page, 7000)
);

await runner.run();

await browser.close();

3. Transform recording

You can customize how a recording is stringified and use it to transform the recording format.

Stringify a recording as a Puppeteer script

import { stringify } from '@puppeteer/replay';

console.log(
  await stringify({
    title: 'Test recording',
    steps: [],
  })
);

Customize how a recording is stringified

You can customize how a recording is stringified by extending the PuppeteerStringifyExtension class as shown in the example below.

Full example of PuppeteerStringifyExtension : link

import { stringify, PuppeteerStringifyExtension } from '@puppeteer/replay';

class Extension extends PuppeteerStringifyExtension {
  // beforeAllSteps?(out: LineWriter, flow: UserFlow): Promise;
  async beforeAllSteps(...args) {
    await super.beforeAllSteps(...args);
    args[0].appendLine('console.log("starting");');
  }

  // beforeEachStep?(out: LineWriter, step: Step, flow: UserFlow): Promise;
  async beforeEachStep(...args) {
    await super.beforeEachStep(...args);
    const [out, step] = args;
    out.appendLine(`console.log("about to execute step ${step.type}")`);
  }

  // afterEachStep?(out: LineWriter, step: Step, flow: UserFlow): Promise;
  async afterEachStep(...args) {
    const [out, step] = args;
    out.appendLine(`console.log("finished step ${step.type}")`);
    await super.afterEachStep(...args);
  }

  // afterAllSteps?(out: LineWriter, flow: UserFlow): Promise;
  async afterAllSteps(...args) {
    args[0].appendLine('console.log("finished");');
    await super.afterAllSteps(...args);
  }
}

console.log(
  await stringify(
    {
      title: 'Test recording',
      steps: [
        {
          type: 'navigate',
          url: 'https://wikipedia.org',
        },
      ],
    },
    {
      extension: new Extension(),
      indentation: '	', // use tab to indent lines
    }
  )
);

Others

Test your extensions using the replay lib

The replay lib offers a canonical recording and a test page that allows to verify that your extension produces all expected side effects on a page.

The test command supports both stringify and runner extensions. The stringify extension will be tested by running the stringified script using node. Run the test using the following command.

npx -p @puppeteer/replay replay-extension-test --ext path-to-your-extension-js

Create a Chrome extension for Recorder (Available from Chrome 104 onwards)

You can create a Chrome extension for Recorder. Refer to the Chrome Extensions documentation for more details on how to extend DevTools.

For example, here are some of the third party extensions:

• Cypress extension lets you export JSON user flows as Cypress test script. Cypress is a front end testing tool built for the modern web.
• WebPageTest extension lets you export user flows from the Recorder directly as WebPageTest Custom scripts to measure site's performance. See Converting user flows to WebPageTest custom scripts to learn more.
• Nightwatch extension lets you export JSON user flows as Nightwatch test script. Nightwatch is an end-to-end testing solution for web applications and websites.
• Testing Library extension lets you export JSON user flows as Testing Library script. Testing Library has simple and complete testing utilities that encourage good testing practices.
• WebdriverIO extension lets you export JSON user flows as WebdriverIO test script. WebdriverIO is an end-to-end testing solution for web, mobile and IoT applications and websites.

This feature only available from Chrome 104 onwards. Check your current Chrome version with chrome://version. Consider installing Chrome Canary to try out cutting-edge features in Chrome.

This repository contains an example extension. Once installed, the Recorder will have a new export option Export as a Custom JSON script in the export dropdown.

To load the example into Chrome DevTools. Follow these steps:

1. Download the chrome-extension folder.
2. Load the folder as unpacked extension in Chrome.
3. Open a recording in the Recorder.
4. Click on export. Now you can see a new Export as a Custom JSON script option in the export menu.

Click and watch the video demo below: