constants.js

/**
 * @license Copyright 2018 The Lighthouse Authors. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
 */
'use strict';

/**
 * Adjustments needed for DevTools network throttling to simulate
 * more realistic network conditions.
 * @see https://crbug.com/721112
 * @see https://docs.google.com/document/d/10lfVdS1iDWCRKQXPfbxEn4Or99D64mvNlugP1AQuFlE/edit
 */
const DEVTOOLS_RTT_ADJUSTMENT_FACTOR = 3.75;
const DEVTOOLS_THROUGHPUT_ADJUSTMENT_FACTOR = 0.9;

const throttling = {
  DEVTOOLS_RTT_ADJUSTMENT_FACTOR,
  DEVTOOLS_THROUGHPUT_ADJUSTMENT_FACTOR,
  // These values align with WebPageTest's definition of "Fast 3G"
  // But offer similar charateristics to roughly the 75th percentile of 4G connections.
  mobileSlow4G: {
    rttMs: 150,
    throughputKbps: 1.6 * 1024,
    requestLatencyMs: 150 * DEVTOOLS_RTT_ADJUSTMENT_FACTOR,
    downloadThroughputKbps: 1.6 * 1024 * DEVTOOLS_THROUGHPUT_ADJUSTMENT_FACTOR,
    uploadThroughputKbps: 750 * DEVTOOLS_THROUGHPUT_ADJUSTMENT_FACTOR,
    cpuSlowdownMultiplier: 4,
  },
  // These values partially align with WebPageTest's definition of "Regular 3G".
  // These values are meant to roughly align with Chrome UX report's 3G definition which are based
  // on HTTP RTT of 300-1400ms and downlink throughput of <700kbps.
  mobileRegular3G: {
    rttMs: 300,
    throughputKbps: 700,
    requestLatencyMs: 300 * DEVTOOLS_RTT_ADJUSTMENT_FACTOR,
    downloadThroughputKbps: 700 * DEVTOOLS_THROUGHPUT_ADJUSTMENT_FACTOR,
    uploadThroughputKbps: 700 * DEVTOOLS_THROUGHPUT_ADJUSTMENT_FACTOR,
    cpuSlowdownMultiplier: 4,
  },
  // Using a "broadband" connection type
  // Corresponds to "Dense 4G 25th percentile" in https://docs.google.com/document/d/1Ft1Bnq9-t4jK5egLSOc28IL4TvR-Tt0se_1faTA4KTY/edit#heading=h.bb7nfy2x9e5v
  desktopDense4G: {
    rttMs: 40,
    throughputKbps: 10 * 1024,
    cpuSlowdownMultiplier: 1,
    requestLatencyMs: 0, // 0 means unset
    downloadThroughputKbps: 0,
    uploadThroughputKbps: 0,
  },
};

/**
 * @type {Required<LH.SharedFlagsSettings['screenEmulation']>}
 */
const MOTOG4_EMULATION_METRICS = {
  mobile: true,
  width: 360,
  height: 640,
  // Moto G4 is really 3, but a higher value here works against
  // our perf recommendations.
  // https://github.com/GoogleChrome/lighthouse/issues/10741#issuecomment-626903508
  deviceScaleFactor: 2.625,
  disabled: false,
};

/**
 * Desktop metrics adapted from emulated_devices/module.json
 * @type {Required<LH.SharedFlagsSettings['screenEmulation']>}
 */
const DESKTOP_EMULATION_METRICS = {
  mobile: false,
  width: 1350,
  height: 940,
  deviceScaleFactor: 1,
  disabled: false,
};

const screenEmulationMetrics = {
  mobile: MOTOG4_EMULATION_METRICS,
  desktop: DESKTOP_EMULATION_METRICS,
};


const MOTOG4_USERAGENT = 'Mozilla/5.0 (Linux; Android 7.0; Moto G (4)) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4695.0 Mobile Safari/537.36 Chrome-Lighthouse'; // eslint-disable-line max-len
const DESKTOP_USERAGENT = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4695.0 Safari/537.36 Chrome-Lighthouse'; // eslint-disable-line max-len

const userAgents = {
  mobile: MOTOG4_USERAGENT,
  desktop: DESKTOP_USERAGENT,
};

/** @type {LH.Config.Settings} */
const defaultSettings = {
  output: 'json',
  maxWaitForFcp: 30 * 1000,
  maxWaitForLoad: 45 * 1000,

  formFactor: 'mobile',
  throttling: throttling.mobileSlow4G,
  throttlingMethod: 'simulate',
  screenEmulation: screenEmulationMetrics.mobile,
  emulatedUserAgent: userAgents.mobile,

  auditMode: false,
  gatherMode: false,
  disableStorageReset: false,
  debugNavigation: false,
  channel: 'node',

  // the following settings have no defaults but we still want ensure that `key in settings`
  // in config will work in a typechecked way
  budgets: null,
  locale: 'en-US', // actual default determined by Config using lib/i18n
  blockedUrlPatterns: null,
  additionalTraceCategories: null,
  extraHeaders: null,
  precomputedLanternData: null,
  onlyAudits: null,
  onlyCategories: null,
  skipAudits: null,
};

/** @type {LH.Config.Pass} */
const defaultPassConfig = {
  passName: 'defaultPass',
  loadFailureMode: 'fatal',
  recordTrace: false,
  useThrottling: false,
  pauseAfterFcpMs: 0,
  pauseAfterLoadMs: 0,
  networkQuietThresholdMs: 0,
  cpuQuietThresholdMs: 0,
  blockedUrlPatterns: [],
  blankPage: 'about:blank',
  gatherers: [],
};

/** @type {Required<LH.Config.NavigationJson>} */
const defaultNavigationConfig = {
  id: 'default',
  loadFailureMode: 'fatal',
  disableThrottling: false,
  disableStorageReset: false,
  pauseAfterFcpMs: 0,
  pauseAfterLoadMs: 0,
  networkQuietThresholdMs: 0,
  cpuQuietThresholdMs: 0,
  blockedUrlPatterns: [],
  blankPage: 'about:blank',
  artifacts: [],
};

const nonSimulatedPassConfigOverrides = {
  pauseAfterFcpMs: 5250,
  pauseAfterLoadMs: 5250,
  networkQuietThresholdMs: 5250,
  cpuQuietThresholdMs: 5250,
};

module.exports = {
  throttling,
  screenEmulationMetrics,
  userAgents,
  defaultSettings,
  defaultPassConfig,
  defaultNavigationConfig,
  nonSimulatedPassConfigOverrides,
};