🎪 jest-puppeteer

Installation

Install packages

npm install --save-dev jest-puppeteer puppeteer jest

Update your Jest configuration

{
  "preset": "jest-puppeteer"
}

Note Be sure to remove any existing testEnvironment option from your Jest configuration.

Write tests

import "expect-puppeteer";

describe("Google", () => {
  beforeAll(async () => {
    await page.goto("https://google.com");
  });

  it('should display "google" text on page', async () => {
    await expect(page).toMatchTextContent("google");
  });
});

Running puppeteer in CI environments

Most continuous integration platforms limit the number of threads one can use. If you have more than one test suite running puppeteer chances are that your test will timeout. This is because jest will try to run puppeteer in parallel and the CI platform won't be able to handle all the parallel jobs in time. A fix to this is to run your test serially when in a CI environment. Users have discovered that running test serially in such environments can render up to 50% of performance gains.

This can be achieved through the CLI by running:

jest --runInBand

Alternatively, you can set jest to use as a max number of workers the amount that your CI environment supports:

jest --maxWorkers=2

Recipes

TypeScript

TypeScript is natively supported from v8.0.0, for previous versions, you have to use types provided by the community.

Writing tests using Puppeteer

Writing integration test can be done using Puppeteer API but it can be complicated and hard because API is not designed for testing.

To make it simpler, expect-puppeteer API add some specific matchers if you make expectation on a Puppeteer Page.

Some examples:

Find a text in the page

// Assert that current page contains 'Text in the page'
await expect(page).toMatchTextContent("Text in the page");

Click a button

// Assert that a button containing text "Home" will be clicked
await expect(page).toClick("button", { text: "Home" });

Fill a form

// Assert that a form will be filled
await expect(page).toFillForm('form[name="myForm"]', {
  firstName: "James",
  lastName: "Bond",
});

Put in debug mode

Debugging tests can be hard sometimes and it is very useful to be able to pause tests in order to inspect the browser. Jest Puppeteer exposes a method jestPuppeteer.debug() that suspends test execution and gives you opportunity to see what's going on in the browser.

await jestPuppeteer.debug();

Start a server

Jest Puppeteer integrates a functionality to start a server when running your test suite. It automatically closes the server when tests are done.

To use it, specify a server section in your jest-puppeteer.config.cjs.

// jest-puppeteer.config.cjs

/** @type {import('jest-environment-puppeteer').JestPuppeteerConfig} */
module.exports = {
  server: {
    command: "node server.js",
    port: 4444,
  },
};

Other options are documented in jest-dev-server.

Configure Puppeteer

Jest Puppeteer automatically detects the best config to start Puppeteer but sometimes you may need to specify custom options.

To run Puppeteer on Firefox, you can set the launch.product property to firefox. By default, the value is chrome which will use Puppeteer on Chromium.

The browser context can be also specified. By default, the browser context is shared (value of default). The incognito value is also available, in case you want more isolation between running instances. More information available in jest-puppeteer-environment readme

Default config values:

// jest-puppeteer.config.cjs

/** @type {import('jest-environment-puppeteer').JestPuppeteerConfig} */
module.exports = {
  launch: {
    dumpio: true,
    headless: process.env.HEADLESS !== "false",
    product: "chrome",
  },
  browserContext: "default",
};

Configure ESLint

Jest Puppeteer exposes five globals: browser, page, context, puppeteerConfig and jestPuppeteer. If you want to avoid errors, you can add them in your ESLint config:

// .eslintrc.js
module.exports = {
  env: {
    jest: true,
  },
  globals: {
    page: true,
    browser: true,
    context: true,
    puppeteerConfig: true,
    jestPuppeteer: true,
  },
};

Custom setupTestFrameworkScriptFile or setupFilesAfterEnv

If you use custom setup files, you'll need to include expect-puppeteer yourself in order to use the matchers it provides. Add the following to your setup file.

// setup.js
require("expect-puppeteer");

// Your custom setup
// ...

// jest.config.js
module.exports = {
  // ...
  setupTestFrameworkScriptFile: "./setup.js",
  // or
  setupFilesAfterEnv: ["./setup.js"],
};

You may want to consider using multiple projects in Jest since setting your own setupFilesAfterEnv and globalSetup can cause globals to be undefined.

module.exports = {
  projects: [
    {
      displayName: "integration",
      preset: "jest-puppeteer",
      transform: {
        "\\.tsx?$": "babel-jest",
        ".+\\.(css|styl|less|sass|scss|png|jpg|ttf|woff|woff2)$":
          "jest-transform-stub",
      },
      moduleNameMapper: {
        "^.+\\.(css|styl|less|sass|scss|png|jpg|ttf|woff|woff2)$":
          "jest-transform-stub",
      },
      modulePathIgnorePatterns: [".next"],
      testMatch: [
        "<rootDir>/src/**/__integration__/**/*.test.ts",
        "<rootDir>/src/**/__integration__/**/*.test.tsx",
      ],
    },
    {
      displayName: "unit",
      transform: {
        "\\.tsx?$": "babel-jest",
        ".+\\.(css|styl|less|sass|scss|png|jpg|ttf|woff|woff2)$":
          "jest-transform-stub",
      },
      moduleNameMapper: {
        "^.+\\.(css|styl|less|sass|scss|png|jpg|ttf|woff|woff2)$":
          "jest-transform-stub",
      },
      globalSetup: "<rootDir>/setupEnv.ts",
      setupFilesAfterEnv: ["<rootDir>/setupTests.ts"],
      modulePathIgnorePatterns: [".next"],
      testMatch: [
        "<rootDir>/src/**/__tests_/**/*.test.ts",
        "<rootDir>/src/**/__tests__/**/*.test.tsx",
      ],
    },
  ],
};

Extend PuppeteerEnvironment

Sometimes you want to use your own environment, to do that you can extend PuppeteerEnvironment.

First, create your own js file for custom environment.

// custom-environment.js
const PuppeteerEnvironment = require("jest-environment-puppeteer");

class CustomEnvironment extends PuppeteerEnvironment {
  async setup() {
    await super.setup();
    // Your setup
  }

  async teardown() {
    // Your teardown
    await super.teardown();
  }
}

module.exports = CustomEnvironment;

Then, assigning your js file path to the testEnvironment property in your Jest configuration.

{
  // ...
  "testEnvironment": "./custom-environment.js"
}

Now your custom setup and teardown will be triggered before and after each test suites.

Create your own globalSetup and globalTeardown

It is possible to create your own globalSetup and globalTeardown.

For this use case, jest-environment-puppeteer exposes two methods: setup and teardown, so that you can wrap them with your own global setup and global teardown methods as the following example:

// global-setup.js
const setupPuppeteer = require("jest-environment-puppeteer/setup");

module.exports = async function globalSetup(globalConfig) {
  await setupPuppeteer(globalConfig);
  // Your global setup
};

// global-teardown.js
const teardownPuppeteer = require("jest-environment-puppeteer/teardown");

module.exports = async function globalTeardown(globalConfig) {
  // Your global teardown
  await teardownPuppeteer(globalConfig);
};

Then assigning your js file paths to the globalSetup and globalTeardown property in your Jest configuration.

{
  // ...
  "globalSetup": "./global-setup.js",
  "globalTeardown": "./global-teardown.js"
}

Now your custom globalSetup and globalTeardown will be triggered once before and after all test suites.

Create React App

You can find an example of create-react-app setup in this repository.

API

global.browser

Give access to the Puppeteer Browser.

it("should open a new page", async () => {
  const page = await browser.newPage();
  await page.goto("https://google.com");
});

global.page

Give access to a Puppeteer Page opened at start (you will use it most of time).

it("should fill an input", async () => {
  await page.type("#myinput", "Hello");
});

global.context

Give access to a browser context that is instantiated when the browser is launched. You can control whether each test has its own isolated browser context using the browserContext option in your config file.

global.expect(page)

Helper to make Puppeteer assertions, see documentation.

await expect(page).toMatchTextContent("A text in the page");
// ...

global.jestPuppeteer.debug()

Put test in debug mode.

• Jest is suspended (no timeout)
• A debugger instruction to Chromium, if Puppeteer has been launched with { devtools: true } it will stop

it("should put test in debug mode", async () => {
  await jestPuppeteer.debug();
});

global.jestPuppeteer.resetPage()

Reset global.page

beforeEach(async () => {
  await jestPuppeteer.resetPage();
});

global.jestPuppeteer.resetBrowser()

Reset global.browser, global.context, and global.page

beforeEach(async () => {
  await jestPuppeteer.resetBrowser();
});

Config

Jest Puppeteer uses cosmiconfig for configuration file support. This means you can configure Jest Puppeteer via (in order of precedence):

• A "jest-puppeteer" key in your package.json file.
• A .jest-puppeteerrc file written in JSON or YAML.
• A .jest-puppeteerrc.json, .jest-puppeteerrc.yml, .jest-puppeteerrc.yaml, or .jest-puppeteerrc.json5 file.
• A .jest-puppeteerrc.js, .jest-puppeteerrc.cjs, jest-puppeteer.config.js, or jest-puppeteer.config.cjs file that exports an object using module.exports.
• A .jest-puppeteerrc.toml file.

By default it looks for config at the root of the project. You can define a custom path using JEST_PUPPETEER_CONFIG environment variable.

It should export a config object or a Promise that returns a config object.

interface JestPuppeteerConfig {
  /**
   * Puppeteer connect options.
   * @see https://pptr.dev/api/puppeteer.connectoptions
   */
  connect?: ConnectOptions;
  /**
   * Puppeteer launch options.
   * @see https://pptr.dev/api/puppeteer.launchoptions
   */
  launch?: PuppeteerLaunchOptions;
  /**
   * Server config for `jest-dev-server`.
   * @see https://www.npmjs.com/package/jest-dev-server
   */
  server?: JestDevServerConfig | JestDevServerConfig[];
  /**
   * Allow to run one browser per worker.
   * @default false
   */
  browserPerWorker?: boolean;
  /**
   * Browser context to use.
   * @default "default"
   */
  browserContext?: "default" | "incognito";
  /**
   * Exit on page error.
   * @default true
   */
  exitOnPageError?: boolean;
  /**
   * Use `runBeforeUnload` in `page.close`.
   * @see https://pptr.dev/api/puppeteer.page.close
   * @default false
   */
  runBeforeUnloadOnClose?: boolean;
}

Sync config

// jest-puppeteer.config.cjs

/** @type {import('jest-environment-puppeteer').JestPuppeteerConfig} */
module.exports = {
  launch: {
    dumpio: true,
    headless: process.env.HEADLESS !== "false",
  },
  server: {
    command: "node server.js",
    port: 4444,
    launchTimeout: 10000,
    debug: true,
  },
};

Async config

This example uses an already running instance of Chrome by passing the active web socket endpoint to connect. This is useful, for example, when you want to connect to Chrome running in the cloud.

// jest-puppeteer.config.cjs
const dockerHost = "http://localhost:9222";

async function getConfig() {
  const data = await fetch(`${dockerHost}/json/version`).json();
  const browserWSEndpoint = data.webSocketDebuggerUrl;
  /** @type {import('jest-environment-puppeteer').JestPuppeteerConfig} */
  return {
    connect: {
      browserWSEndpoint,
    },
    server: {
      command: "node server.js",
      port: 3000,
      launchTimeout: 10000,
      debug: true,
    },
  };
}

module.exports = getConfig();

Inspiration

Thanks to Fumihiro Xue for his great Jest example.