View source for TestEngineering/Performance/Talos/Development

= Environment =
{{warning|Talos currently requires Python 2.7}}
Prerequisites: Local clone of mozilla-central and a successful [https://developer.mozilla.org/en-US/docs/Simple_Firefox_build mozilla-central Firefox build] completed.

= Testing your patch locally =
Testing locally involves running some subset of the Talos tests on desktop and possibly mobile.  Obviously not all permutations of tests and the ways of running them can be tried, so common sense should be used as to what is run. You may also want to run the [https://searchfox.org/mozilla-central/source/testing/talos/talos/unittests Talos harness tests].{{todo|document how to run Talos harness tests}}

You should tailor your choice of tests to pick those that cover what you've changed programmatically, but in general you should probably run at least one startup test and one pageloader test. A good baseline might be the 'tresize' and 'tsvgx' test suites.

{{warning|The following is currently broken. Once {{bug|1573429}} is resolved we can update this to use {{code|mach talos-test}}}}
Run the tests from mozilla-central/testing/talos (with the venv activated, as noted above):

  talos --develop --executablePath pathtofirefox --activeTests tart

The {{code|--develop}} option indicates to run in develop mode and store the results in local.json + local.out.

The {{code|--executablePath}} option tells Talos where the firefox installation we want to run is located (i.e. '~/mozilla/objdir/dist/bin/firefox' or whatever the full path is to your firefox executable that will be running the tests).

The {{code|--activeTests}} argument provides a list of tests we want to run (if running multiple tests, separate each test name with ':').

For a list of complete options:

  talos --help

= Testing your patch on try =

Just push your Talos patch to the try server. See [[../Running#Try_server]].