Telemetry Tests

Telemetry has few suites of unit tests:

  • telemetry_unittests in catapult: catapult/telemetry/bin/run_tests. This suite verifies the core framework functions against the stable browser.
  • telemetry_unittests in chromium repo: src/tools/perf/run_telemetry_tests. This suite verifies the core framework functions against your browser built in chromium environment.
  • telemetry_perf_unittests: src/tools/perf/run_tests. This suite verifies that Chromium benchmarks are using the framework function properly.

These are functional tests that do not depend on performance.

Triaging failures

  • Is there a native stack? Since these tests interact with a lot of recorded real world content, they unintentionally end up serving as integration tests which frequently uncover Chromium crashes. If you see a native crash stack (after a TabCrashException or BrowserGoneException), this is guaranteed to be a browser issue. Usually scanning the change log for patches that touch files that show up in the stack will point to the culprit to revert.
  • Is there a Python stack? If there's a Python-only exception, it is very likely, but not guaranteed to be a Telemetry breakage. Look for Telemetry changes in the range for a culprit.
  • Is there a timeout? These could go either way and are tricky to diagnose, move on to local diagnostics.

Running the tests locally

  • Preparing your devices for testing: go/telemetry-device-setup (Googler only for now, sorry!)
  • Authenticate into Cloud Storage.
  • Run test via: $ catapult/telemetry/run_tests <test> --browser=<browser> --chrome-root=<path to chromium src/ dir> Where <test> can be: BrowserTest.testForegroundTab or BrowserTest as a “wildcard” by matching the sub string "BrowserTest". Where <path to chromium src/ dir> is the full path including the src/ at the end and <browser> can be: release, android-chrome-shell, list (for a full list)

Disabling tests

Tests should generally only be disabled for flakiness. Consistent failures should be diagnosed and the culprit reverted.

The @decorators.Disabled and @decorators.Enabled decorators may be added above any test to enable or disable it. They optionally accept a list of platforms, os versions or browser types. Examples:

from telemetry import decorators
  • @decorators.Disabled('all') # Disabled everywhere
  • @decorators.Enabled('mac') # Only runs on mac
  • @decorators.Disabled('xp') # Run everywhere except windows xp
  • @decorators.Disabled('debug') # Run everywhere except debug builds