Xvfb, Jenkins, Selenium tests - Capture Screenshots of all pages

Question

I'm trying to find some clues on the following issues and not able to find good help online.

I'm running Xvfb (X virtual frame buffer), firefox on a Linux machine in headless mode. Xvfb main service is up and running and DISPLAY variable is set.

/usr/bin/Xvfb :99 -ac -screen 0 1600x1200x16

I have some automated selenium based tests which I'm running using Gradle (gradle test). They run successfully and in Jenkins I'm able to get this working using Xvfb plugin. JUnit post publish report/result info and Gradle's reports/test/index.html file is showing successful test run.

I just run the following to run tests in Gradle: gradle test -DsomePropConfigFileForEnv=SomeSourceConfigFilewithPathvalue

My questions:
1. How can I get the screenshots of all the pages that this automated test/run is rendering (i.e. login page, application main page after login, user clicks on the main page here and there (i.e. opening/clicking on various tabs, links, tables, buttons etc) and finally log out page.

I'm able to get the screenshot from the Xvfb_screen<N> file, which is getting created under -fbdir folder (what we specify while running Xvfb via a Jenkins job) but the screenshot is a Black page if test runs successfully (this can be due to the 2nd bullet I mentioned below) --OR it's a valid single page image screenshot (if an error is encountered during the test run).

I'm trying to get all the pages which the automated Selenium tests are rendering (the config file I passed to Gradle as a -D parameter has URLs / user name / browser, version etc info in it). PS: It's not just for some random URL that I'm trying to get an image screenshot using Xvfb DISPLAY virtual frame buffer.

2. During the test, I see there's a valid virtual framebuffer file, with a valid size.

For ex: While Jenkins job is in progress and running Gradle test task and Xvfb plugin has started a new xvfb instance, I see:

/production/JSlaves/kobaloki2_1/xvfb-2015-02-04_01-16-37-6170319257811815857.fbdir/Xvfb_screen0

but as soon as the test is complete (or errors our), this file is getting deleted from this xxxx.fbdir folder and there's no file at all.

Why is this file getting deleted.

If it'll remain there, then I can use xwd/xwud command and other tools (imagemagick convert etc commands) to create an image file as a POST BUILD action or even within the BUILD section after "Invoke Gradle" step.

The following command will create a .png image file of the firefox screenshot (only one page screenshot) and assuming xvfb is running on DISPLAY=:107

xwd -root -display :107 | convert xwd:- /tmp/capture2.png

and the following xvfb process (which is still running, containing a valid Xvfb_screen**** file in it - which was created by the Jenkins job where Xvfb plugin is configured with offset base 100 and 7 is the node/build number thus, making :107 as DISPLAY number).

u10002  30717 19950  1 01:16 ?        00:00:00 Xvfb :107 -screen 0 1024x768x8 -fbdir /production/JSlaves/kobaloki2_1/xvfb-2015-02-04_01-16-37-6170319257811815857.fbdir

3. I'm not running Xvfb / Imagemagick etc to just get an image of a URL (ex: www.google.com) but trying to get all the screenshots what a test is rendering behind Xvfb memory virtual framebuffer/file during the test run.

Are there any other tools (simple enough to install without messing up with the Linux server) which can achieve the same (capturing screenshots of all the pages that a test is rendering behind Xvf/firefox/Linux server in Headless way)?

I also tried Selenium Grid server, but FF is acting up there (due to some reason) thus I'm trying to run these tests using Jenkins, Gradle, Xvfb plugin on a Linux server (Headless mode) using firefox browser and planning to have N no. of executors to run multiple runs of these tests and finally capturing the results per run.

I'm archiving the artifacts (if any) and using Image Gallery plugin as well, but don't have the images for all the rendered pages which ran in Selenium behind Xvfb/firefox.

Any inputs are greatly appreciated.

Thanks.

Answer 1

If you're running with Selenium then you could use driver.getScreenshotAs()

http://docs.seleniumhq.org/docs/04_webdriver_advanced.jsp

Set this at the end of a step or method where you want a screenshot and output it to disc.

Answer 2

OK, this is what I did. This approach doesn't require any change to the source code of the project.

1. Installed imagemagick (..ck) i.e. yum install imagemagick on RHEL.
   
2. Created a script on the target server and it works now. All I do is, in the Jenkins job, when I have already started the Xvfb instance (using Xvfb plugin in Jenkins), then just a second before before running the Selenium GUI tests via Gradle (or any build tool), I call the following script and pass the parameters (where DISPLAY variable value is available to the Jenkins job as we are using Xvfb plugin in it). At the end of tests, the script exists automatically (as xwd command doesn't get any more input so it exits gracefully) and finally I publish the images and .mp4 (video) file on Jenkins (as a side bar link to show Test results / video) and archive the artifacts (.png image files using "Image Galary Plugin" and .mp4 file).
   
3. NOTE: This requires that your machine has: imagemagick, xwd and ffmpeg installed. If the options passed to any commands differs acc. to your OS machine, then tweak it accordingly. The framerate value in ffmpeg command can be a fraction i.e. 1/5 or 0.5 or 15 or anything you want (try it and see what you get).
   
4. It's up to you, if you want to ARCHIVE this big amount of data or not. You can do it if you have good space and if your Jenkins job have a better old build clean retention policies.

---

#!bin/bash
##
## This script will capture Screenshot (every 0.1 seconds) of an automated GUI (for ex: Selenium tests) tests running behind a HEADLESS Xvfb display instance.
## Then, it'll create a mp4 format movie using the captured screenshots.
##
## Machine where you run this script, should have: Xvfb service running, a session started by Xvfb plugin via Jenkins, xwd,ffmpeg OS commands and imagemagick (utilities).
## - For ex, try this on RHEL to install imagemagick:  yum install imagemagick
##
## Variables
ws=$1;                                                  ## Workspace folder location
d=$2; d=$(echo $d | tr -d ':');                         ## Display number associated with the Xvfb instance started by Xvfb plugin from a Jenkins job
wscapdir=${ws}/capturebrowserss;                        ## Workspace capture browser's screen shot folder
if [[ -n $3 ]]; then wscapdir=${wscapdir}/$3; fi        ## If a user pass a 3rd parameter i.e. a Jenkins BUILD_NUMBER, then create a child directory with that name to archive that specific run.
i=1;
rm -fr ${wscapdir} 2>/dev/null || ( echo - Oh Oh.. Cant remove ${wscapdir} folder; echo -e "-- Still exiting gracefully! \n"; exit 0);
mkdir -p ${wscapdir}
while : ; do
 xwd -root -display :$d 2>/dev/null | convert xwd:- ${wscapdir}/capFile_${d}_dispId`printf "%08d" $i`.png 2>/dev/null;
 if [[ ${PIPESTATUS[0]} -gt 0 || ${PIPESTATUS[1]} -gt 0 ]]; then echo -e "\n-- Something bad happened during xwd or imagemagick convert command, manually check it.\n"; exit 0; fi
 ((i++)); sleep 0.1;
done
ffmpeg -r 5 -i ${wscapdir}/capFile_dispId_%08d.png ${wscapdir}/out_byRateOf5.mp4 2>/dev/null || echo -e "\n-- Some error occurred (may be too many files opened), exiting gracefully!\n";