a little madness

Earlier in the year I put Selenium in a cage using Xnest. This allows me to run browser-popping tests in the background without disturbing my desktop or (crucially) stealing my focus.

On that post Rohan stopped by to mention a nice alternative to Xnest: Xephyr. As the Xephyr homepage will tell you:

Xephyr is a kdrive based X Server which targets a window on a host X Server as its framebuffer. Unlike Xnest it supports modern X extensions ( even if host server doesn’t ) such as Composite, Damage, randr etc (no GLX support now). It uses SHM Images and shadow framebuffer updates to provide good performance. It also has a visual debugging mode for observing screen updates.

It sounded sweet, but I hadn’t tried it out until recently, on a newer box where I didn’t already have Xnest setup. The good news is the setup is as simple as with Xnest in my prior post:

1. Install Xephyr: which runs an X server inside a window:
   $ sudo apt-get install xserver-xephyr
2. Install a simple window manager: again, for old times’ sake, I’ve gone for fvwm:
   $ sudo apt-get install fvwm
3. Start Xephyr: choose an unused display number (most standard setups will already be using 0) — I chose 1. As with Xnest, the -ac flag turns off access control, which you might want to be more careful about. My choice of window size is largely arbitrary:
   $ Xephyr :1 -screen 1024×768 -ac &
4. Set DISPLAY: so that subsequent X programs connect to Xephyr, you need to set the environment variable DISPLAY to whatever you passed as the first argument to Xephyr above:
   $ export DISPLAY=:1
5. Start your window manager: to manage windows in your nested X instance:
   $ fvwm &
6. Run your tests: however you normally would:
   $ ant accept.master

Then just sit back and watch the browsers launched by Selenium trapped in the Xephyr window. Let’s see them take your focus now!

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This entry was posted on Tuesday, December 1st, 2009 at 12:31 am and is filed under Agile, Build, Continuous Integration, Project Automation, Technology, Testing. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.