What to do when Firefox crashes under test automation with Selenium

If you have the task to create automated tests for websites you will most likely make use of Selenium when it comes to testing UI interactions. To execute the tests for the various browsers out there each browser vendor offers a so called driver package  which has to be used by Selenium to run each of the commands. In case of Firefox this will be geckodriver.

Within the last months we got a couple of issues reported for geckodriver that Firefox sometimes crashes while the tests are running. This feedback is great, and we always appreciate because it helps us to make Firefox more stable and secure for our users. But to actually being able to fix the crash we would need some more data, which was a bit hard to retrieve in the past.

As first step I worked on the Firefox crash reporter support for geckodriver and we got it enabled in the 0.19.0 release. While this was fine and the crash reporter created minidump files for each of the crashes in the temporarily created user profile for Firefox, this data gets also removed together with the profile once the test has been finished. So copying the data out of the profile was impossible.

As of now I haven’t had the time to improve the user experience here, but I hope to be able to do it soon. The necessary work which already got started will be covered on bug 1433495. Once the patch on that bug has been landed and a new geckodriver version released, the environment variable “MINIDUMP_SAVE_PATH” can be used to specify a target location for the minidump files. Then geckodriver will automatically copy the files to this target folder before the user profile gets removed.

But until that happened a bit of manual work is necessary. Because I had to mention those steps a couple of time and I don’t want to repeat that in the near future again and again, I decided to put up a documentation in how to analyze the crash data, and how to send the data to us. The documentation can be found at:

https://firefox-source-docs.mozilla.org/testing/geckodriver/doc/geckodriver/CrashReports.html

I hope that helps!