Function compareExperimentLists

scripts/check_experiments.js:208–267

* Compares list of experiments, fires error if an experiment is registered without telemetry entry.

(mainImplList, userMetricsList)

 * Compares list of experiments, fires error if an experiment is registered without telemetry entry.
 */
function compareExperimentLists(mainImplList, userMetricsList) {
  // Ensure both lists are valid
  let errorFound = false;
  if (!mainImplList) {
    console.log(
        'Changes to Devtools Experiment registration have prevented this check from finding registered experiments.',
    );
    console.log(
        'Please update scripts/check_experiments.js to account for the new experiment registration.',
    );
    errorFound = true;
  }
  if (!userMetricsList) {
    console.log(
        'Changes to Devtools Experiment UserMetrics enum have prevented this check from finding experiments registered for telemetry.',
    );
    console.log(
        'Please update scripts/check_experiments.js to account for the new experiment telemetry format.',
    );
    errorFound = true;
  }
  if (errorFound) {
    process.exit(1);
  }

  // Ensure both lists match
  const missingTelemetry = mainImplList.filter(
      experiment => !userMetricsList.includes(experiment),
  );
  const staleTelemetry = userMetricsList.filter(
      experiment => !mainImplList.includes(experiment),
  );
  if (missingTelemetry.length) {
    console.log(
        'Devtools Experiments have been added without corresponding histogram update!',
    );
    console.log(missingTelemetry.join('\n'));
    console.log(
        'Please ensure that the DevtoolsExperiments enum in UserMetrics.ts is updated with the new experiment.',
    );
    console.log(
        'Please ensure that a corresponding CL is opened against chromium.src/tools/metrics/histograms/metadata/dev/enums.xml to update the DevtoolsExperiments enum',
    );
    errorFound = true;
  }
  if (staleTelemetry.length) {
    console.log(
        'Devtools Experiments that are no longer registered are still listed in the telemetry enum!',
    );
    console.log(staleTelemetry.join('\n'));
    console.log(
        'Please ensure that the DevtoolsExperiments enum in UserMetrics.ts is updated to remove these stale experiments.',
    );
    errorFound = true;
  }
  if (errorFound) {
    process.exit(1);
  }