Headless Browser Testing with Chrome and Firefox

When utilising Selenium to test web applications, I was always under the impression that PhantomJS was the only option for servers without an X server. I have nothing but good things to say about PhantomJS and have used it successfully for testing in the past. However, while working on some pull requests for splinter recently, I discovered that Chrome and Firefox can also be configured to do the same thing.

To begin with, download the Google Chrome debian package using a regular PC and upload it to your server.

Install Chrome as follows:

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sudo apt-get install xdg-utils
sudo dpkg -i google-chrome-stable_current_amd64.deb

In addition to Chrome, you’ll also need the Chrome Driver. Download this on a regular PC and upload the zip file to your server.

Now extract it to /usr/bin and set appropriate permissions:

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sudo unzip chromedriver_linux64.zip -d /usr/bin/
sudo chmod 755 /usr/bin/chromedriver

Next up, we’ll install Firefox:

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sudo apt-get install firefox

To make use of a regular browser in Selenium sessions, we need to install the X Virtual Framebuffer and related fonts:

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sudo apt-get install xvfb x11-xkb-utils
sudo apt-get install xfonts-100dpi xfonts-75dpi xfonts-scalable xfonts-cyrillic

Now that everything’s installed, you may start up a virtual display. Each virtual display has a number. I’ll use display number 99 below to setup our example display.

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Xvfb :99 &
export DISPLAY=:99

An even better way of starting and stopping an xvfb session in your Python code is with the use of xvfbwrapper.

Install it as follows in your virtualenv:

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pip install xvfbwrapper

And here’s some sample code to get you started:

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from xvfbwrapper import Xvfb

def main():
    # TODO create your Selenium object and initialise the browser
    xvfb = Xvfb()
    try:
        xvfb.start()
        # TODO run some selenium tests here
        xvfb.stop()
    except OSError:
        print(
            'Error: xvfb cannot be found on your system, please install '
            'it and try again')
        exit(1)
    finally:
        # TODO clean up Selenium browser

if __name__ == '__main__':
    main()

Another popular option is PyVirtualDisplay but I couldn’t get that working when I tried it. I’ll need to look into why soon.

xvfbwrapper is robust and has no dependencies so I honestly had no reason to really pursue PyVirtualDisplay but it’s a similar library and worth a look too.

One of the biggest challenges one may face when testing like this is the multitude of OS and browser combinations. On bigger projects where browser and OS compatibility are very important, you may wish to use a service such as Sauce to perform your testing. Their service gives access to over 300 browser/OS combinations and is free for open source projects.

Have fun! :)