12.3.1 • Public • Published



Mocha testing in Electron. This project has two main value propositions:

  1. You can now test any JavaScript app in a real browser environment.
  2. You can now test your Electron apps!


npm i -g electron-mocha


Install Electron

First, you need to install Electron. You can either run:

npm i -g electron

and then electron will be added to your path. Or, you can download a version from https://github.com/electron/releases and then set an environment variable ELECTRON_PATH pointing to the binary. Note if you're using Mac OS X, the path would be to the actual executable and not the app directory e.g. /Applications/Electron.app/Contents/MacOS/Electron.

Run Tests

electron-mocha is almost a drop-in replacement for the regular mocha command, with these additional options:

--renderer              Run tests in renderer process              [boolean]
--require-main, --main  Require module in main process             [array]
--script                Load module in renderer via script tag     [array]
--interactive           Show renderer tests in persistent window   [boolean]
--url, --index          Load custom URL in renderer                [string]
--preload               Load module during renderer preload        [string]
--window-config         Supply custom Electron window options      [string]
-W, --warnings          Print renderer warnings to console         [boolean]
--show-window           Show the window during tests               [boolean

The window-config switch must point to a JSON file or to a JavaScript module that exports an options object. For more information, check out the Electron API docs.

For the full list of available options, see electron-mocha --help.



This runs all tests in your test directory in the main process.

electron-mocha --renderer

This runs all tests in your test directory in a renderer process. This means that you have access to the entirety of the DOM, web storage, etc. This is because it's actually running in a Chromium process.

Using for CI

In most Linux CI environments you'll need to use XFVB to run your tests. Either start the appropriate XVFB service or use xvfb-run.

WebGL Tests

If you are writing tests for WebGL programs and you cannot get a WebGL contexts, this may be because the environment doesn't have GPU support. You can pass --ignore-gpu-blacklist to Electron to bypass it:

  • command
electron-mocha --main ignore-gpu-blacklist.js
  • ignore-gpu-blacklist.js
const { app } = require('electron');

Debugger Support

Use the --inspect or --inspect-brk options to enable Electron's debugger. When using --renderer this will show the test-runner window dev-tools, including a debugger (so you do not need to attach a node-inspector).

Note that the window will close automatically when the tests have finished, therefore this option should be used in combination with debugger statements anywhere in your tests or code.

Alternatively, you can use the --interactive option which will keep the window open after your tests have run (you can reload the window to run the tests again), to give you the opportunity to set breakpoints using the dev-tools inspector.

To debug the main process, you will need to start a node-inspector separately.

Code Coverage

You can use electron-mocha to collect code coverage data in both Electron's main and renderer processes. To do this, you will need to instrument your code, run the tests on the instrumented code, and save the coverage stats after all tests have finished.

For examples, see this thread



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npm i electron-mocha

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  • inukshuk
  • jprichardson