core: add TestedAsMobileDevice base artifact (#7280)

lighthouse-core/audits/content-width.js

@@ -19,26 +19,21 @@ class ContentWidth extends Audit {
       description: 'If the width of your app\'s content doesn\'t match the width ' +
           'of the viewport, your app might not be optimized for mobile screens. ' +
           '[Learn more](https://developers.google.com/web/tools/lighthouse/audits/content-sized-correctly-for-viewport).',
-      requiredArtifacts: ['ViewportDimensions', 'HostUserAgent'],
+      requiredArtifacts: ['ViewportDimensions', 'TestedAsMobileDevice'],
     };
   }
 
   /**
    * @param {LH.Artifacts} artifacts
-   * @param {LH.Audit.Context} context
    * @return {LH.Audit.Product}
    */
-  static audit(artifacts, context) {
-    const userAgent = artifacts.HostUserAgent;
+  static audit(artifacts) {
+    const IsMobile = artifacts.TestedAsMobileDevice;
     const viewportWidth = artifacts.ViewportDimensions.innerWidth;
     const windowWidth = artifacts.ViewportDimensions.outerWidth;
     const widthsMatch = viewportWidth === windowWidth;
 
-    const isMobileHost = userAgent.includes('Android') || userAgent.includes('Mobile');
-    const isMobile = context.settings.emulatedFormFactor === 'mobile' ||
-      (context.settings.emulatedFormFactor !== 'desktop' && isMobileHost);
-
-    if (isMobile) {
+    if (IsMobile) {
       return {
         rawValue: widthsMatch,
         explanation: this.createExplanation(widthsMatch, artifacts.ViewportDimensions),

lighthouse-core/gather/gather-runner.js

@@ -395,10 +395,19 @@ class GatherRunner {
    * @return {Promise<LH.BaseArtifacts>}
    */
   static async getBaseArtifacts(options) {
+    const hostUserAgent = (await options.driver.getBrowserVersion()).userAgent;
+
+    const {emulatedFormFactor} = options.settings;
+    // Whether Lighthouse was run on a mobile device (i.e. not on a desktop machine).
+    const IsMobileHost = hostUserAgent.includes('Android') || hostUserAgent.includes('Mobile');
+    const TestedAsMobileDevice = emulatedFormFactor === 'mobile' ||
+      (emulatedFormFactor !== 'desktop' && IsMobileHost);
+
     return {
       fetchTime: (new Date()).toJSON(),
       LighthouseRunWarnings: [],
-      HostUserAgent: (await options.driver.getBrowserVersion()).userAgent,
+      TestedAsMobileDevice,
+      HostUserAgent: hostUserAgent,
       NetworkUserAgent: '', // updated later
       BenchmarkIndex: 0, // updated later
       WebAppManifest: null, // updated later

lighthouse-core/test/audits/content-width-test.js

@@ -13,25 +13,12 @@ const assert = require('assert');
 describe('Mobile-friendly: content-width audit', () => {
   it('fails when scroll width differs from viewport width', () => {
     const result = Audit.audit({
-      HostUserAgent: 'Desktop',
+      TestedAsMobileDevice: true,
       ViewportDimensions: {
         innerWidth: 100,
         outerWidth: 300,
       },
-    }, {settings: {emulatedFormFactor: 'mobile'}});
-
-    assert.equal(result.rawValue, false);
-    assert.ok(result.explanation);
-  });
-
-  it('fails when host user agent is a phone', () => {
-    const result = Audit.audit({
-      HostUserAgent: 'Mobile Android',
-      ViewportDimensions: {
-        innerWidth: 100,
-        outerWidth: 300,
-      },
-    }, {settings: {emulatedFormFactor: 'none'}});
+    });
 
     assert.equal(result.rawValue, false);
     assert.ok(result.explanation);
@@ -47,13 +34,13 @@ describe('Mobile-friendly: content-width audit', () => {
     }, {settings: {emulatedFormFactor: 'mobile'}}).rawValue, true);
   });
 
-  it('not applicable when device emulation is turned off', () => {
+  it('not applicable when run on desktop', () => {
     return assert.equal(Audit.audit({
-      HostUserAgent: 'Mobile Android Chrome',
+      TestedAsMobileDevice: false,
       ViewportDimensions: {
         innerWidth: 300,
         outerWidth: 450,
       },
-    }, {settings: {emulatedFormFactor: 'desktop'}}).notApplicable, true);
+    }).notApplicable, true);
   });
 });

lighthouse-core/test/gather/fake-driver.js

@@ -5,6 +5,79 @@
  */
 'use strict';
 
+function makeFakeDriver({protocolGetVersionResponse}) {
+  return {
+    getBrowserVersion() {
+      return Promise.resolve(Object.assign({}, protocolGetVersionResponse, {milestone: 71}));
+    },
+    getBenchmarkIndex() {
+      return Promise.resolve(125.2);
+    },
+    getAppManifest() {
+      return Promise.resolve(null);
+    },
+    connect() {
+      return Promise.resolve();
+    },
+    disconnect() {
+      return Promise.resolve();
+    },
+    gotoURL() {
+      return Promise.resolve('https://www.reddit.com/r/nba');
+    },
+    beginEmulation() {
+      return Promise.resolve();
+    },
+    setThrottling() {
+      return Promise.resolve();
+    },
+    dismissJavaScriptDialogs() {
+      return Promise.resolve();
+    },
+    assertNoSameOriginServiceWorkerClients() {
+      return Promise.resolve();
+    },
+    reloadForCleanStateIfNeeded() {
+      return Promise.resolve();
+    },
+    enableRuntimeEvents() {
+      return Promise.resolve();
+    },
+    evaluateScriptOnLoad() {
+      return Promise.resolve();
+    },
+    cleanBrowserCaches() {},
+    clearDataForOrigin() {},
+    cacheNatives() {
+      return Promise.resolve();
+    },
+    evaluateAsync() {
+      return Promise.resolve({});
+    },
+    registerPerformanceObserver() {
+      return Promise.resolve();
+    },
+    beginTrace() {
+      return Promise.resolve();
+    },
+    endTrace() {
+      return Promise.resolve(
+      require('../fixtures/traces/progressive-app.json')
+      );
+    },
+    beginDevtoolsLog() {},
+    endDevtoolsLog() {
+      return require('../fixtures/artifacts/perflog/defaultPass.devtoolslog.json');
+    },
+    blockUrlPatterns() {
+      return Promise.resolve();
+    },
+    setExtraHTTPHeaders() {
+      return Promise.resolve();
+    },
+  };
+}
+
 // https://chromedevtools.github.io/devtools-protocol/tot/Browser#method-getVersion
 const protocolGetVersionResponse = {
   protocolVersion: '1.3',
@@ -14,77 +87,16 @@ const protocolGetVersionResponse = {
   userAgent: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3577.0 Safari/537.36',
   jsVersion: '7.1.314',
 };
+const fakeDriver = makeFakeDriver({protocolGetVersionResponse});
 
-const fakeDriver = {
-  getBrowserVersion() {
-    return Promise.resolve(Object.assign({}, protocolGetVersionResponse, {milestone: 71}));
-  },
-  getBenchmarkIndex() {
-    return Promise.resolve(125.2);
-  },
-  getAppManifest() {
-    return Promise.resolve(null);
-  },
-  connect() {
-    return Promise.resolve();
-  },
-  disconnect() {
-    return Promise.resolve();
-  },
-  gotoURL() {
-    return Promise.resolve('https://www.reddit.com/r/nba');
-  },
-  beginEmulation() {
-    return Promise.resolve();
-  },
-  setThrottling() {
-    return Promise.resolve();
-  },
-  dismissJavaScriptDialogs() {
-    return Promise.resolve();
-  },
-  assertNoSameOriginServiceWorkerClients() {
-    return Promise.resolve();
-  },
-  reloadForCleanStateIfNeeded() {
-    return Promise.resolve();
+const fakeDriverUsingRealMobileDevice = makeFakeDriver({
+  protocolGetVersionResponse: {
+    ...protocolGetVersionResponse,
+    // eslint-disable-next-line max-len
+    userAgent: 'Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5 Build/MRA58N) AppleWebKit/537.36(KHTML, like Gecko) Chrome/69.0.3464.0 Mobile Safari/537.36',
   },
-  enableRuntimeEvents() {
-    return Promise.resolve();
-  },
-  evaluateScriptOnLoad() {
-    return Promise.resolve();
-  },
-  cleanBrowserCaches() {},
-  clearDataForOrigin() {},
-  cacheNatives() {
-    return Promise.resolve();
-  },
-  evaluateAsync() {
-    return Promise.resolve({});
-  },
-  registerPerformanceObserver() {
-    return Promise.resolve();
-  },
-  beginTrace() {
-    return Promise.resolve();
-  },
-  endTrace() {
-    return Promise.resolve(
-      require('../fixtures/traces/progressive-app.json')
-    );
-  },
-  beginDevtoolsLog() {},
-  endDevtoolsLog() {
-    return require('../fixtures/artifacts/perflog/defaultPass.devtoolslog.json');
-  },
-  blockUrlPatterns() {
-    return Promise.resolve();
-  },
-  setExtraHTTPHeaders() {
-    return Promise.resolve();
-  },
-};
+});
 
 module.exports = fakeDriver;
+module.exports.fakeDriverUsingRealMobileDevice = fakeDriverUsingRealMobileDevice;
 module.exports.protocolGetVersionResponse = protocolGetVersionResponse;

lighthouse-core/test/gather/gather-runner-test.js

@@ -33,6 +33,7 @@ class TestGathererNoArtifact extends Gatherer {
 }
 
 const fakeDriver = require('./fake-driver');
+const fakeDriverUsingRealMobileDevice = fakeDriver.fakeDriverUsingRealMobileDevice;
 
 function getMockedEmulationDriver(emulationFn, netThrottleFn, cpuThrottleFn,
   blockUrlFn, extraHeadersFn) {
@@ -156,6 +157,50 @@ describe('GatherRunner', function() {
     });
   });
 
+  describe('collects TestedAsMobileDevice as an artifact', () => {
+    const url = 'https://example.com';
+
+    it('works when running on desktop device without emulation', async () => {
+      const driver = fakeDriver;
+      const config = new Config({passes: [{}]});
+      const settings = {};
+      const options = {url, driver, config, settings};
+
+      const results = await GatherRunner.run(config.passes, options);
+      expect(results.TestedAsMobileDevice).toBe(false);
+    });
+
+    it('works when running on desktop device with mobile emulation', async () => {
+      const driver = fakeDriver;
+      const config = new Config({passes: [{}]});
+      const settings = {emulatedFormFactor: 'mobile'};
+      const options = {url, driver, config, settings};
+
+      const results = await GatherRunner.run(config.passes, options);
+      expect(results.TestedAsMobileDevice).toBe(true);
+    });
+
+    it('works when running on mobile device without emulation', async () => {
+      const driver = fakeDriverUsingRealMobileDevice;
+      const config = new Config({passes: [{}]});
+      const settings = {};
+      const options = {url, driver, config, settings};
+
+      const results = await GatherRunner.run(config.passes, options);
+      expect(results.TestedAsMobileDevice).toBe(true);
+    });
+
+    it('works when running on mobile device with desktop emulation', async () => {
+      const driver = fakeDriverUsingRealMobileDevice;
+      const config = new Config({passes: [{}]});
+      const settings = {emulatedFormFactor: 'desktop'};
+      const options = {url, driver, config, settings};
+
+      const results = await GatherRunner.run(config.passes, options);
+      expect(results.TestedAsMobileDevice).toBe(false);
+    });
+  });
+
   it('sets up the driver to begin emulation when all emulation flags are undefined', () => {
     const tests = {
       calledDeviceEmulation: false,

lighthouse-core/test/results/artifacts/artifacts.json

@@ -1,6 +1,7 @@
 {
   "LighthouseRunWarnings": [],
   "BenchmarkIndex": 1000,
+  "TestedAsMobileDevice": true,
   "HostUserAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3358.0 Safari/537.36",
   "NetworkUserAgent": "Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5 Build/MRA58N) AppleWebKit/537.36(KHTML, like Gecko) Chrome/66.0.3359.30 Mobile Safari/537.36",
   "fetchTime": "2018-03-13T00:55:45.840Z",

types/artifacts.d.ts

@@ -23,6 +23,8 @@ declare global {
       fetchTime: string;
       /** A set of warnings about unexpected things encountered while loading and testing the page. */
       LighthouseRunWarnings: string[];
+      /** Whether the page was loaded on either a real or emulated mobile device. */
+      TestedAsMobileDevice: boolean;
       /** The user agent string of the version of Chrome used. */
       HostUserAgent: string;
       /** The user agent string that Lighthouse used to load the page. */