Chrome OS Debugging Instructions

Chrome on Chrome OS is tested using a handful of frameworks, each of which you‘ll find running on Chrome’s CQ and waterfalls. If you're investigating failures in these tests, below are some tips for debugging and identifying the cause.

This doc outlines tests running in true Chrome OS environments (ie: on virtual machines or real devices). linux-chromeos tests, on the other hand, can be debugged like any other linux test.


Tast is Chrome OS‘s integration testing framework. Since Chrome itself is instrumental to the Chrome OS system, it’s equally important that we run some of these integration tests on Chrome's waterfalls. If you find one of these tests failing (likely in the chrome_all_tast_tests step), you can:

  • Inspect the failed test's log snippet: There should be a log link for each failed test with failure information. eg: For this failed build, opening the platform.Histograms log link contains stack traces and error messages.

  • View browser & system logs: A common cause of failure on Chrome‘s builders are browser crashes. When this happens, each test’s log snippets will simply contain warnings like “Chrome probably crashed”. To debug these crashes, navigate to the test‘s Isolated output, most likely listed in the build under the test step’s shard #0 isolated out link. From there, view the various log/chrome/... or log/ui/... text files and you should find some with browser crashes and stack traces.

To disable a test on Chrome‘s builders, the preferred method is to add the informational attribute to the test’s definition (see Tast attributes for more info). Note that this requires a full Chrome OS checkout. If that‘s not an option, or if it needs to be disabled ASAP, you can add it to the list of disabled tests for the step’s GN target. For example, to disable a test in the chrome_all_tast_tests step, add it to this list.


TODO: Add instructions for debugging telemetry failures.


TODO: Add instructions for debugging GTest failures.

Rerunning these tests locally

TODO: Add instructions for rerunning these tests locally.