Development with Python

3. Check out

as a way of controlling virtual displays from Python.

I would look into using headless browsers as a “dev-only” tool, to

speed up the running of FTs on the developer’s machine, while the

tests on the CI server use actual browsers.

The alternative is to set up a virtual display: we get the server to pretend it has a screen

attached to it, so Firefox runs happily. There’s a few tools out there to do this; we’ll use

one called “Xvfb” (X Virtual Framebuffer)

because it’s easy to install and use, and be‐

cause it has a convenient Jenkins plugin.

We go back to our project and hit “Configure” again, then find the section called “Build

Environment”. Using the virtual display is as simple as ticking the box marked “Start

Xvfb before the build, and shut it down after,” as in

Figure 20-8. Sometimes config is easy

The build does much better now:

[...]

Xvfb starting$ /usr/bin/Xvfb :2 -screen 0 1024x768x24 -fbdir

/var/lib/jenkins/2013-11-04_03-27-221510012427739470928xvfb

[...]

+ python manage.py test lists accounts

...................................................

---------------------------------------------------------------------

Ran 51 tests in 0.410s

Creating test database for alias 'default'...

Destroying test database for alias 'default'...

+ pip install selenium

Requirement already satisfied (use --upgrade to upgrade): selenium in

/var/lib/jenkins/shiningpanda/jobs/ddc1aed1/virtualenvs/d41d8cd9/lib/python3.3/site-packages

Setting Up a Virtual Display so the FTs Can Run Headless

373