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Thursday, April 26, 2012

Headless tests with Firefox WebDriver

There are times when you don't want a browser popping each time you execute the test. Or you just don't have privilege of having a browser display like in UNIX based system running your CI and not having any display. These are the times when you would find it right to execute your tests in headless browser mode.

What we need -
  • Xvfb: X virtual frame buffer is X11 server which does graphical operation in memory, hence no output is displayed. Wikipedia has more on it.
  • Firefox: World famous open source browser
  • A simple selenium test: As simple as launching Google in Firefox
First we need to install Xvfb and FF on Ubantu as -

sudo apt-get install Xvfb firefox

Not you can start Xvfb as -

Xvfb :1 -screen 0 1024x768x24 &

From manual of Xvfb -
-screen screennum WxHxD
           This option creates screen screennum and sets  its  width,  height,
           and  depth  to W, H, and D respectively.  By default, only screen 0
           exists and has the dimensions 1280x1024x8.
Now comes the selenium test. You need to guide Firefox so that it executes test in Xvfb started in previous steps.
This could be done by setting System level property for Xvfb as -

String Xport = System.getProperty("lmportal.xvfb.id", ":1");

and directing Firefox binary to use Xvfb as -

        FirefoxBinary firefoxBinary = new FirefoxBinary();
        firefoxBinary.setEnvironmentProperty("DISPLAY", Xport);
        WebDriver driver = new FirefoxDriver(firefoxBinary, null);


If Firefox is not installed in standard location - /usr/bin/firefox then you can also specify path to Firefox binary as -

        final File firefoxPath = new File(System.getProperty(
                "lmportal.deploy.firefox.path", "/usr/bin/firefox"));
        FirefoxBinary firefoxBinary = new FirefoxBinary(firefoxPath);
        firefoxBinary.setEnvironmentProperty("DISPLAY", Xport);
        WebDriver driver = new FirefoxDriver(firefoxBinary, null);


Whole test looks as -

On execution, FF will be launched in Xvfb and snap shot of google would be saved in your test directory. Since it is headless execution of test, you would not really see any browser popping on your screen.

To execute headless tests in Chrome, start chrome driver as -


ChromeDriverService chromeDriverService = new ChromeDriverService.Builder()
.usingChromeDriverExecutable(
new File(ChromeDriverLocation
.getchromeDriverLocation()))
.usingAnyFreePort().withEnvironment(
ImmutableMap.of("DISPLAY", ":1")).build();
chromeDriverService.start();
driver = new ChromeDriver(chromeDriverService);

9 comments:

  1. Great article, I've been struggling with this for several days, thanks!

    PS. Is it something wrong with my browser or it's impossible to select & copy any text on this page?:)

    ReplyDelete
  2. Thanks, this article helped to understand how headless browser can be used

    ReplyDelete
  3. How can this be done for Internet Explorer on Microsoft Windows (a more common use case than Firefox and Ubuntu...)?

    ReplyDelete
    Replies
    1. I came across this on SO - http://stackoverflow.com/questions/16637744/how-to-run-selenium-browsers-in-the-background-in-windows

      Delete
  4. i got entire message as result URL. can you help me? :(

    ReplyDelete
    Replies
    1. which message? could you add more details?

      Delete
  5. on entering
    sudo apt-get install Xvfb firefox
    I am getting the error : Unable to locate package Xvfb

    ReplyDelete
  6. I did exactly like that, and I get this error:

    >>>>>
    Failed to connect to binary FirefoxBinary(/usr/bin/firefox) on port
    7055; process output follows:
    (process:7466): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
    Xlib: extension "RANDR" missing on display ":1".
    (firefox:7466): GConf-WARNING **: Client failed to connect to the D-BUS daemon:
    Failed to connect to socket /tmp/dbus-gMDGmLxvLi: Connection refused
    Build info: version: '2.44.0', revision: '76d78cf', time: '2014-10-23 20:03:00'
    System info: host: 'cpro22808', ip: '176.143.4.171', os.name: 'Linux', os.arch: 'amd64', os.version: '3.13.0-32-generic', java.version:
    '1.7.0_55'
    Driver info: driver.version: FirefoxDriver
    <<<<<<

    When I run Xvfb I get a RANDR log that its inilializing fine.

    Can someone help me? Thanks.

    ReplyDelete

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