WDIO Electron Service

WebdriverIO service for testing Electron applications

Enables cross-platform E2E testing of electron apps via the extensive WebdriverIO ecosystem. Adds electron-specific browser capabilities and handles chromedriver execution.

Spiritual successor to Spectron (RIP).

Installation

npm i -D wdio-electron-service

Or use your package manager of choice - pnpm, yarn, etc.

You will need to install WebdriverIO, instructions can be found here.

Chromedriver

wdio-electron-service needs chromedriver to work. The chromedriver version needs to be appropriate for the version of electron that your app was built with, as of v4 you can specify the electron version that you are using and the service will download and use the appropriate version of chromedriver for your app.

Custom Configuration

If you prefer to manage chromedriver yourself you can install it directly or via some other means like electron-chromedriver, in this case you will need to tell the service where your chromedriver binary is. You can do this by specifying the chromedriverCustomPath property.

npm i -D chromedriver@100  # for Electron 18 apps

        chromedriver: {
          port: 9519,
          logFileName: 'wdio-chromedriver.log',
          chromedriverCustomPath: require.resolve('chromedriver/bin/chromedriver') // resolves to chromedriver binary
        },

Example Configuration

To use the service you need to add electron to your services array, followed by a configuration object:

// wdio.conf.js
import { join } from 'path';
import fs from 'fs';
import { getDirname } from 'cross-dirname';

const dirname = getDirname();
const packageJson = JSON.parse(fs.readFileSync('./package.json'));
const {
  build: { productName },
} = packageJson;

export const config = {
  outputDir: 'all-logs',
  // ...
  services: [
    [
      'electron',
      {
        appPath: join(dirname, 'dist'),
        appName: productName,
        appArgs: ['foo', 'bar=baz'],
        chromedriver: {
          port: 9519,
          logFileName: 'wdio-chromedriver.log',
        },
        electronVersion: '23.1.0',
      },
    ],
  ],
  // ...
};

API Configuration

If you wish to use the electron APIs then you will need to import (or require) the preload and main scripts in your app. Somewhere near the top of your preload:

if (isTest) {
  import('wdio-electron-service/preload');
}

And somewhere near the top of your main index file (app entry point):

if (isTest) {
  import('wdio-electron-service/main');
}

The APIs should not work outside of WDIO but for security reasons it is encouraged to use dynamic imports wrapped in conditionals to ensure the APIs are only exposed when the app is being tested.

After importing the scripts the APIs should now be available in tests.

Currently available APIs: app, browserWindow, dialog, mainProcess.

The service re-exports the WDIO browser object with the .electron namespace for API usage in your tests:

import { browser } from 'wdio-electron-service';

// in a test
const appName = await browser.electron.app('getName');

Mocking Electron APIs

You can mock electron API functionality by calling the mock function with the API name, function name and mock return value. e.g. in a spec file:

await browser.electron.mock('dialog', 'showOpenDialog', 'dialog opened!');
const result = await browser.electron.dialog('showOpenDialog');
console.log(result); // 'dialog opened!'

Custom Electron API

You can also implement a custom API if you wish. To do this you will need to define a handler in your main process:

import { ipcMain } from 'electron';

ipcMain.handle('wdio-electron', () => {
  // access some Electron or Node things on the main process
  return 'such api';
});

The custom API can then be called in a spec file:

const someValue = await browser.electron.api('wow'); // default
const someValue = await browser.electron.myCustomAPI('wow'); // configured using `customApiBrowserCommand`

Example

See the Example App and E2Es for an example of "real-world" usage in testing a minimal electron app.

Configuration

appPath: string

The path to the built app for testing. In a typical electron project this will be where electron-builder is configured to output, e.g. dist by default. Required to be used with appName as both are needed in order to generate a path to the electron binary.

appName: string

The name of the built app for testing. Required to be used with appPath as both are needed in order to generate a path to the Electron binary.

It needs to match the name of the install directory used by electron-builder; this value is derived from your electron-builder configuration and will be either the name property (from package.json) or the productName property (from electron-builder config). You can find more information regarding this in the electron-builder documentation.

binaryPath: string

The path to the electron binary of the app for testing. The path generated by using appPath and appName is tied to electron-builder output, if you are implementing something custom then you can use this.

electronVersion: string

The version of electron that the app to be tested was built with. The service uses this value to download the appropriate version of chromedriver. It is not required if you are specifying a chromedriverCustomPath.

appArgs: string[]

An array of string arguments to be passed through to the app on execution of the test run. Electron command line switches and some Chromium switches can be used here.

customApiBrowserCommand: string

default api

The browser command used to access the custom electron API.

Chromedriver configuration

This service wraps the wdio-chromedriver-service, you can configure the following options which will be passed through to that service:

chromedriver.port: number

default 9515

The port on which chromedriver should run.

chromedriver.path: string

default /

The path on which chromedriver should run.

chromedriver.protocol: string

default http

The protocol chromedriver should use.

chromedriver.hostname: string

default localhost

The hostname chromedriver should use.

chromedriver.pollTimeOut: number

default 10000

The startup timeout of ChromeDriver in ms, it checks if the port is open before starting ChromeDriver and then checks again if it is closed after starting.

chromedriver.outputDir: string

default defined by config.outputDir

The path where the output log of the chromedriver server should be stored. If not specified, the WDIO outputDir config property is used and chromedriver logs are written to the same directory as the WDIO logs.

chromedriver.logFileName: string

default wdio-chromedriver.log

The name of the output log file to be written in the outputDir.

chromedriver.chromedriverCustomPath: string

The path of the chromedriver binary to be executed. If not specified, the service will install the appropriate version of Chromedriver for the specified electronVersion.

Support

If you are having issues running WDIO you should open a discussion in the main WDIO forum in the first instance.

The electron service discussion forum is much less active than the WDIO one, but if the issue you are experiencing is specific to electron or using the service then you can open a discussion here.

Common Issues

DevToolsActivePort file doesn't exist

This is a Chromium error which may appear when using Docker or CI. Most of the "fixes" discussed online are based around passing different combinations of args to Chromium - you can set these via appArgs, though in most cases using xvfb has proven to be more effective; the service itself uses a github action to achieve this when running E2Es on CI.

See this discussion for more details.