409 lines
13 KiB
Markdown
409 lines
13 KiB
Markdown
# Automated Testing
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Test automation is an efficient way of validating that your application code works as intended.
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While Electron doesn't actively maintain its own testing solution, this guide will go over a couple
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ways you can run end-to-end automated tests on your Electron app.
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## Using the WebDriver interface
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From [ChromeDriver - WebDriver for Chrome][chrome-driver]:
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> WebDriver is an open source tool for automated testing of web apps across many
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> browsers. It provides capabilities for navigating to web pages, user input,
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> JavaScript execution, and more. ChromeDriver is a standalone server which
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> implements WebDriver's wire protocol for Chromium. It is being developed by
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> members of the Chromium and WebDriver teams.
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There are a few ways that you can set up testing using WebDriver.
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### With WebdriverIO
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[WebdriverIO](https://webdriver.io/) (WDIO) is a test automation framework that provides a
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Node.js package for testing with WebDriver. Its ecosystem also includes various plugins
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(e.g. reporter and services) that can help you put together your test setup.
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#### Install the testrunner
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First you need to run the WebdriverIO starter toolkit in your project root directory:
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```sh npm2yarn
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npx wdio . --yes
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```
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This installs all necessary packages for you and generates a `wdio.conf.js` configuration file.
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#### Connect WDIO to your Electron app
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Update the capabilities in your configuration file to point to your Electron app binary:
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```javascript title='wdio.conf.js'
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export.config = {
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// ...
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capabilities: [{
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browserName: 'chrome',
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'goog:chromeOptions': {
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binary: '/path/to/your/electron/binary', // Path to your Electron binary.
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args: [/* cli arguments */] // Optional, perhaps 'app=' + /path/to/your/app/
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}
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}]
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// ...
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}
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```
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#### Run your tests
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To run your tests:
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```sh
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$ npx wdio run wdio.conf.js
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```
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### With Selenium
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[Selenium](https://www.selenium.dev/) is a web automation framework that
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exposes bindings to WebDriver APIs in many languages. Their Node.js bindings
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are available under the `selenium-webdriver` package on NPM.
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#### Run a ChromeDriver server
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In order to use Selenium with Electron, you need to download the `electron-chromedriver`
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binary, and run it:
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```sh npm2yarn
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npm install --save-dev electron-chromedriver
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./node_modules/.bin/chromedriver
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Starting ChromeDriver (v2.10.291558) on port 9515
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Only local connections are allowed.
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```
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Remember the port number `9515`, which will be used later.
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#### Connect Selenium to ChromeDriver
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Next, install Selenium into your project:
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```sh npm2yarn
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npm install --save-dev selenium-webdriver
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```
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Usage of `selenium-webdriver` with Electron is the same as with
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normal websites, except that you have to manually specify how to connect
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ChromeDriver and where to find the binary of your Electron app:
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```js title='test.js'
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const webdriver = require('selenium-webdriver')
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const driver = new webdriver.Builder()
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// The "9515" is the port opened by ChromeDriver.
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.usingServer('http://localhost:9515')
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.withCapabilities({
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'goog:chromeOptions': {
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// Here is the path to your Electron binary.
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binary: '/Path-to-Your-App.app/Contents/MacOS/Electron'
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}
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})
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.forBrowser('chrome') // note: use .forBrowser('electron') for selenium-webdriver <= 3.6.0
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.build()
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driver.get('http://www.google.com')
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driver.findElement(webdriver.By.name('q')).sendKeys('webdriver')
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driver.findElement(webdriver.By.name('btnG')).click()
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driver.wait(() => {
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return driver.getTitle().then((title) => {
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return title === 'webdriver - Google Search'
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})
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}, 1000)
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driver.quit()
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```
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## Using Playwright
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[Microsoft Playwright](https://playwright.dev) is an end-to-end testing framework built
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using browser-specific remote debugging protocols, similar to the [Puppeteer] headless
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Node.js API but geared towards end-to-end testing. Playwright has experimental Electron
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support via Electron's support for the [Chrome DevTools Protocol] (CDP).
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### Install dependencies
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You can install Playwright through your preferred Node.js package manager. The Playwright team
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recommends using the `PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD` environment variable to avoid
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unnecessary browser downloads when testing an Electron app.
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```sh npm2yarn
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PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1 npm install --save-dev playwright
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```
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Playwright also comes with its own test runner, Playwright Test, which is built for end-to-end
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testing. You can also install it as a dev dependency in your project:
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```sh npm2yarn
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npm install --save-dev @playwright/test
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```
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:::caution Dependencies
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This tutorial was written `playwright@1.16.3` and `@playwright/test@1.16.3`. Check out
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[Playwright's releases][playwright-releases] page to learn about
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changes that might affect the code below.
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:::
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:::info Using third-party test runners
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If you're interested in using an alternative test runner (e.g. Jest or Mocha), check out
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Playwright's [Third-Party Test Runner][playwright-test-runners] guide.
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:::
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### Write your tests
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Playwright launches your app in development mode through the `_electron.launch` API.
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To point this API to your Electron app, you can pass the path to your main process
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entry point (here, it is `main.js`).
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```js {5}
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const { _electron: electron } = require('playwright')
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const { test } = require('@playwright/test')
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test('launch app', async () => {
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const electronApp = await electron.launch({ args: ['main.js'] })
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// close app
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await electronApp.close()
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})
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```
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After that, you will access to an instance of Playwright's `ElectronApp` class. This
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is a powerful class that has access to main process modules for example:
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```js {6-11}
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const { _electron: electron } = require('playwright')
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const { test } = require('@playwright/test')
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test('get isPackaged', async () => {
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const electronApp = await electron.launch({ args: ['main.js'] })
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const isPackaged = await electronApp.evaluate(async ({ app }) => {
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// This runs in Electron's main process, parameter here is always
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// the result of the require('electron') in the main app script.
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return app.isPackaged
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})
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console.log(isPackaged) // false (because we're in development mode)
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// close app
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await electronApp.close()
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})
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```
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It can also create individual [Page][playwright-page] objects from Electron BrowserWindow instances.
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For example, to grab the first BrowserWindow and save a screenshot:
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```js {6-7}
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const { _electron: electron } = require('playwright')
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const { test } = require('@playwright/test')
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test('save screenshot', async () => {
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const electronApp = await electron.launch({ args: ['main.js'] })
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const window = await electronApp.firstWindow()
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await window.screenshot({ path: 'intro.png' })
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// close app
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await electronApp.close()
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})
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```
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Putting all this together using the PlayWright Test runner, let's create a `example.spec.js`
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test file with a single test and assertion:
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```js title='example.spec.js'
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const { _electron: electron } = require('playwright')
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const { test, expect } = require('@playwright/test')
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test('example test', async () => {
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const electronApp = await electron.launch({ args: ['.'] })
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const isPackaged = await electronApp.evaluate(async ({ app }) => {
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// This runs in Electron's main process, parameter here is always
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// the result of the require('electron') in the main app script.
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return app.isPackaged;
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});
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expect(isPackaged).toBe(false);
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// Wait for the first BrowserWindow to open
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// and return its Page object
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const window = await electronApp.firstWindow()
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await window.screenshot({ path: 'intro.png' })
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// close app
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await electronApp.close()
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});
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```
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Then, run Playwright Test using `npx playwright test`. You should see the test pass in your
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console, and have an `intro.png` screenshot on your filesystem.
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```console
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☁ $ npx playwright test
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Running 1 test using 1 worker
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✓ example.spec.js:4:1 › example test (1s)
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```
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:::info
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Playwright Test will automatically run any files matching the `.*(test|spec)\.(js|ts|mjs)` regex.
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You can customize this match in the [Playwright Test configuration options][playwright-test-config].
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:::
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:::tip Further reading
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Check out Playwright's documentation for the full [Electron][playwright-electron]
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and [ElectronApplication][playwright-electronapplication] class APIs.
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:::
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## Using a custom test driver
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It's also possible to write your own custom driver using Node.js' built-in IPC-over-STDIO.
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Custom test drivers require you to write additional app code, but have lower overhead and let you
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expose custom methods to your test suite.
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To create a custom driver, we'll use Node.js' [`child_process`](https://nodejs.org/api/child_process.html) API.
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The test suite will spawn the Electron process, then establish a simple messaging protocol:
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```js title='testDriver.js'
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const childProcess = require('child_process')
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const electronPath = require('electron')
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// spawn the process
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const env = { /* ... */ }
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const stdio = ['inherit', 'inherit', 'inherit', 'ipc']
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const appProcess = childProcess.spawn(electronPath, ['./app'], { stdio, env })
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// listen for IPC messages from the app
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appProcess.on('message', (msg) => {
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// ...
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})
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// send an IPC message to the app
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appProcess.send({ my: 'message' })
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```
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From within the Electron app, you can listen for messages and send replies using the Node.js
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[`process`](https://nodejs.org/api/process.html) API:
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```js title='main.js'
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// listen for messages from the test suite
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process.on('message', (msg) => {
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// ...
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})
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// send a message to the test suite
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process.send({ my: 'message' })
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```
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We can now communicate from the test suite to the Electron app using the `appProcess` object.
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For convenience, you may want to wrap `appProcess` in a driver object that provides more
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high-level functions. Here is an example of how you can do this. Let's start by creating
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a `TestDriver` class:
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```js title='testDriver.js'
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class TestDriver {
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constructor ({ path, args, env }) {
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this.rpcCalls = []
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// start child process
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env.APP_TEST_DRIVER = 1 // let the app know it should listen for messages
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this.process = childProcess.spawn(path, args, { stdio: ['inherit', 'inherit', 'inherit', 'ipc'], env })
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// handle rpc responses
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this.process.on('message', (message) => {
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// pop the handler
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const rpcCall = this.rpcCalls[message.msgId]
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if (!rpcCall) return
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this.rpcCalls[message.msgId] = null
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// reject/resolve
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if (message.reject) rpcCall.reject(message.reject)
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else rpcCall.resolve(message.resolve)
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})
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// wait for ready
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this.isReady = this.rpc('isReady').catch((err) => {
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console.error('Application failed to start', err)
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this.stop()
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process.exit(1)
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})
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}
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// simple RPC call
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// to use: driver.rpc('method', 1, 2, 3).then(...)
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async rpc (cmd, ...args) {
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// send rpc request
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const msgId = this.rpcCalls.length
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this.process.send({ msgId, cmd, args })
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return new Promise((resolve, reject) => this.rpcCalls.push({ resolve, reject }))
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}
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stop () {
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this.process.kill()
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}
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}
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module.exports = { TestDriver };
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```
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In your app code, can then write a simple handler to receive RPC calls:
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```js title='main.js'
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const METHODS = {
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isReady () {
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// do any setup needed
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return true
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}
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// define your RPC-able methods here
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}
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const onMessage = async ({ msgId, cmd, args }) => {
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let method = METHODS[cmd]
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if (!method) method = () => new Error('Invalid method: ' + cmd)
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try {
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const resolve = await method(...args)
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process.send({ msgId, resolve })
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} catch (err) {
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const reject = {
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message: err.message,
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stack: err.stack,
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name: err.name
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}
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process.send({ msgId, reject })
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}
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}
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if (process.env.APP_TEST_DRIVER) {
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process.on('message', onMessage)
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}
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```
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Then, in your test suite, you can use your `TestDriver` class with the test automation
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framework of your choosing. The following example uses
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[`ava`](https://www.npmjs.com/package/ava), but other popular choices like Jest
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or Mocha would work as well:
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```js title='test.js'
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const test = require('ava')
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const electronPath = require('electron')
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const { TestDriver } = require('./testDriver')
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const app = new TestDriver({
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path: electronPath,
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args: ['./app'],
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env: {
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NODE_ENV: 'test'
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}
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})
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test.before(async t => {
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await app.isReady
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})
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test.after.always('cleanup', async t => {
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await app.stop()
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})
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```
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[chrome-driver]: https://sites.google.com/chromium.org/driver/
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[Puppeteer]: https://github.com/puppeteer/puppeteer
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[playwright-electron]: https://playwright.dev/docs/api/class-electron/
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[playwright-electronapplication]: https://playwright.dev/docs/api/class-electronapplication
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[playwright-page]: https://playwright.dev/docs/api/class-page
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[playwright-releases]: https://github.com/microsoft/playwright/releases
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[playwright-test-config]: https://playwright.dev/docs/api/class-testconfig#test-config-test-match
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[playwright-test-runners]: https://playwright.dev/docs/test-runners/
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[Chrome DevTools Protocol]: https://chromedevtools.github.io/devtools-protocol/
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