Being based on Chromium, Electron requires a display driver to function. If Chromium can't find a display driver, Electron will fail to launch - and therefore not executing any of your tests, regardless of how you are running them. Testing Electron-based apps on Travis, Circle, Jenkins or similar Systems requires therefore a little bit of configuration. In essence, we need to use a virtual display driver.
Configuring the Virtual Display Server
First, install Xvfb. It's a virtual framebuffer, implementing the X11 display server protocol - it performs all graphical operations in memory without showing any screen output, which is exactly what we need.
Then, create a virtual Xvfb screen and export an environment variable called DISPLAY that points to it. Chromium in Electron will automatically look for
$DISPLAY, so no further configuration of your app is required. This step can be automated with Anaïs Betts' xvfb-maybe: Prepend your test commands with
xvfb-maybe and the little tool will automatically configure Xvfb, if required by the current system. On Windows or macOS, it will do nothing.
## On Windows or macOS, this invokes electron-mocha
## On Linux, if we are in a headless environment, this will be equivalent
## to xvfb-run electron-mocha ./test/*.js
xvfb-maybe electron-mocha ./test/*.js
On Travis, your
.travis.yml should look roughly like this:
- export DISPLAY=':99.0'
- Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 &
For Jenkins, a Xvfb plugin is available.
Circle CI is awesome and has Xvfb and
$DISPLAY already set up, so no further configuration is required.
AppVeyor runs on Windows, supporting Selenium, Chromium, Electron and similar tools out of the box - no configuration is required.