Field Trial Testing Configuration

This directory contains the field trial configuration used to ensure testing coverage of the experiments defined in fieldtrial_testing_config.json.

Note that these apply specifically for Chromium builds. Chrome branded / official builds do not use these definitions.

The first available experiment after platform filtering and concatenation is the default experiment for Chromium builds. This experiment is also used for perf bots and browser tests in the waterfall.

Config File Format

{
    "StudyName": [
        {
            "platforms": [Array of Strings of Valid Platforms for These Experiments],
            "experiments": [
                {
                    "//0": "Comment Line 0. Lines 0-9 are supported.",
                    "name": "ExperimentName",
                    "params": {Dictionary of Params},
                    "enable_features": [Array of Strings of Features],
                    "disable_features": [Array of Strings of Features]
                },
                ...
            ]
        },
        ...
    ],
    ...
}

The config file is a dictionary at the top level mapping a study name to an array of study configurations. The study name should match the Field Trial study name.

Study Configurations

Each study configuration is a dictionary containing both platform and experiments.

platform is an array of strings of valid platforms and the strings may be android, chromeos, ios, linux, mac, or windows.

experiments is an array containing the experiments.

The converter uses the platforms array to determine what experiments to include for the study. All matching platforms will have their experiments concatenated together for the study.

Experiments (Groups)

Each experiment is a dictionary that must contain the name key, identifying the experiment group name which should match the Field Trial experiment group name.

The remaining keys, params, enable_features, and disable_features are optional.

params is a dictionary mapping parameter name to parameter.

enable_features and disable_features indicate which features should be enabled and disabled respectively through the Feature List API. As a reminder, as the variations framework does not actually fetch the Field Trial definitions from the server for Chromium builds, so any feature enabling or disabling must be done here.

Comments

Each experiment may have up to 10 lines of comments. The comment key must be of the form //N where N is between 0 and 9.

{
    "AStudyWithExperimentComment": [
        {
            "platforms": ["chromeos", "linux", "mac", "win"],
            "experiments": [
                {
                    "//0": "This is the first comment line.",
                    "//1": "This is the second comment line.",
                    "name": "DesktopExperiment"
                }
            ]
        }
    ]
}

Specifying Different Experiments for Different Platforms

Simply specify two different study configurations in the study:

{
    "DifferentExperimentsPerPlatform": [
        {
            "platforms": ["chromeos", "linux", "mac", "win"],
            "experiments": [{ "name": "DesktopExperiment" }]
        },
        {
            "platforms": ["android", "ios"],
            "experiments": [{ "name": "MobileExperiment" }]
        }
    ]
}

Presubmit

The presubmit tool will ensure that your changes follow the correct ordering and format.