Javascript - Jest-puppeteer with typescript configuration

How to install and configure puppeteer with Jest and Typescript.

You should have the configuration explained on this page: Jest and Typescript installation / configuration.

• Install the library

yarn add jest-puppeteer puppeteer --dev

• install the puppeteer type file

yarn add @types/puppeteer --dev
yarn add @types/jest-environment-puppeteer --dev
yarn add @types/expect-puppeteer --dev

• Add them also in the compile path

{
  "compilerOptions": {
   .....
    "types": [
     .......
      "puppeteer",
      "jest-environment-puppeteer",
      "expect-puppeteer"
    ]
  }

• Merge the ts-jest and jest-puppeteer

const ts_preset = require('ts-jest/jest-preset')
const puppeteer_preset = require('jest-puppeteer/jest-preset')


module.exports = Object.assign(
    ts_preset, 
    puppeteer_preset
)

• Change the config

preset: './js/Preset.js'

• Uncomment testEnvironment

// testEnvironment: "node"

This configuration is not mandatory but will make a debugger keyword in the javascript code stop the execution by:

• starting puppeteer not in headless mode
• opening the devtool

let jest_puppeteer_conf = {
    launch: {
        timeout: 30000,
        dumpio: true // Whether to pipe the browser process stdout and stderr 
    }
}

const isDebugMode = typeof v8debug === 'object' || /--debug|--inspect/.test(process.execArgv.join(' '));

if (isDebugMode) {
    jest_puppeteer_conf.launch.headless = false; // for debug:  to see what the browser is displaying
    jest_puppeteer_conf.launch.slowMo = 250;  // slow down by 250ms for each step
    jest_puppeteer_conf.launch.devtools = true; // This lets you debug code in the application code browser
    jest_puppeteer_conf.launch.args = [ '--start-maximized' ]; // maximise the screen
}

module.exports = jest_puppeteer_conf;

Puppeteer's page and browser classes are automatically be exposed.

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

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

• Run

jest

• Result

PASS  js/__tests__/Google.test.ts (5.688s)
  Google
    √ should display "google" text on page (9ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        5.807s
Ran all test suites.

await jestPuppeteer.debug()

TypeScript diagnostics (customize using `[jest-config].globals.ts-jest.diagnostics` option):
    js/__tests__/Google.test.ts:17:15 - error TS2304: Cannot find name 'page'.

    17         await page.goto('https://google.com')
                     ~~~~

be sure to add the types in your compile path of the tsconfig.json file.

Be sure to uncomment testEnvironment

// testEnvironment: "node"

• https://jestjs.io/docs/en/puppeteer
• https://github.com/smooth-code/jest-puppeteer