From 45defa8c5feb529513b58f72ab788387104b5265 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Fri, 30 Apr 2021 16:42:31 -0400
Subject: [PATCH 01/17] start

---
 lighthouse-core/gather/gather-runner.js       | 13 ++++-
 .../gather/gatherers/link-elements.js         | 56 ++++++++++++++-----
 lighthouse-core/index.js                      |  3 +-
 lighthouse-core/runner.js                     | 13 +++--
 types/gatherer.d.ts                           |  6 ++
 5 files changed, 69 insertions(+), 22 deletions(-)

diff --git a/lighthouse-core/gather/gather-runner.js b/lighthouse-core/gather/gather-runner.js
index d95108ed92c5..11495771c80f 100644
--- a/lighthouse-core/gather/gather-runner.js
+++ b/lighthouse-core/gather/gather-runner.js
@@ -8,7 +8,7 @@
 const log = require('lighthouse-logger');
 const LHError = require('../lib/lh-error.js');
 const NetworkAnalyzer = require('../lib/dependency-graph/simulator/network-analyzer.js');
-const NetworkRecorder = require('../lib/network-recorder.js');
+const NetworkRecords = require('../computed/network-records.js');
 const emulation = require('../lib/emulation.js');
 const constants = require('../config/constants.js');
 const i18n = require('../lib/i18n/i18n.js');
@@ -54,6 +54,7 @@ const SLOW_CPU_BENCHMARK_INDEX_THRESHOLD = 1000;
 const str_ = i18n.createMessageInstanceIdFn(__filename, UIStrings);
 
 /** @typedef {import('../gather/driver.js')} Driver */
+/** @typedef {import('../lib/arbitrary-equality-map.js')} ArbitraryEqualityMap */
 
 /**
  * Each entry in each gatherer result array is the output of a gatherer phase:
@@ -477,7 +478,12 @@ class GatherRunner {
     };
     log.time(status);
     const devtoolsLog = driver.endDevtoolsLog();
-    const networkRecords = NetworkRecorder.recordsFromLogs(devtoolsLog);
+    const context = {
+      computedCache: passContext.computedCache,
+      settings: passContext.settings,
+      options: {},
+    };
+    const networkRecords = await NetworkRecords.request(devtoolsLog, context);
     log.timeEnd(status);
 
     return {
@@ -707,7 +713,7 @@ class GatherRunner {
 
   /**
    * @param {Array<LH.Config.Pass>} passConfigs
-   * @param {{driver: Driver, requestedUrl: string, settings: LH.Config.Settings}} options
+   * @param {{driver: Driver, requestedUrl: string, settings: LH.Config.Settings, computedCache: Map<string, ArbitraryEqualityMap>}} options
    * @return {Promise<LH.Artifacts>}
    */
   static async run(passConfigs, options) {
@@ -737,6 +743,7 @@ class GatherRunner {
           settings: options.settings,
           passConfig,
           baseArtifacts,
+          computedCache: options.computedCache,
           LighthouseRunWarnings: baseArtifacts.LighthouseRunWarnings,
         };
         const passResults = await GatherRunner.runPass(passContext);
diff --git a/lighthouse-core/gather/gatherers/link-elements.js b/lighthouse-core/gather/gatherers/link-elements.js
index 90c6fb6c606b..50f4a25ddc1c 100644
--- a/lighthouse-core/gather/gatherers/link-elements.js
+++ b/lighthouse-core/gather/gatherers/link-elements.js
@@ -6,10 +6,12 @@
 'use strict';
 
 const LinkHeader = require('http-link-header');
-const Gatherer = require('./gatherer.js');
+const FRGatherer = require('../../fraggle-rock/gather/base-gatherer.js');
 const {URL} = require('../../lib/url-shim.js');
+const NetworkRecords = require('../../computed/network-records.js');
 const NetworkAnalyzer = require('../../lib/dependency-graph/simulator/network-analyzer.js');
 const pageFunctions = require('../../lib/page-functions.js');
+const DevtoolsLog = require('./devtools-log.js');
 
 /* globals HTMLLinkElement getNodeDetails */
 
@@ -79,9 +81,15 @@ function getLinkElementsInDOM() {
 }
 /* c8 ignore stop */
 
-class LinkElements extends Gatherer {
+class LinkElements extends FRGatherer {
+  /** @type {LH.Gatherer.GathererMeta<'DevtoolsLog'>} */
+  meta = {
+    supportedModes: ['timespan', 'navigation'],
+    dependencies: {DevtoolsLog: DevtoolsLog.symbol},
+  }
+
   /**
-   * @param {LH.Gatherer.PassContext} passContext
+   * @param {LH.Gatherer.CompatibilityContext} passContext
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
   static getLinkElementsInDOM(passContext) {
@@ -98,14 +106,13 @@ class LinkElements extends Gatherer {
   }
 
   /**
-   * @param {LH.Gatherer.PassContext} passContext
-   * @param {LH.Gatherer.LoadData} loadData
-   * @return {LH.Artifacts['LinkElements']}
+   * @param {LH.Gatherer.CompatibilityContext} passContext
+   * @param {LH.Artifacts.NetworkRequest[]} networkRecords
+   * @return {Promise<LH.Artifacts['LinkElements']>}
    */
-  static getLinkElementsInHeaders(passContext, loadData) {
+  static async getLinkElementsInHeaders(passContext, networkRecords) {
     const finalUrl = passContext.url;
-    const records = loadData.networkRecords;
-    const mainDocument = NetworkAnalyzer.findMainDocument(records, finalUrl);
+    const mainDocument = NetworkAnalyzer.findMainDocument(networkRecords, finalUrl);
 
     /** @type {LH.Artifacts['LinkElements']} */
     const linkElements = [];
@@ -131,13 +138,13 @@ class LinkElements extends Gatherer {
   }
 
   /**
-   * @param {LH.Gatherer.PassContext} passContext
-   * @param {LH.Gatherer.LoadData} loadData
+   * @param {LH.Gatherer.CompatibilityContext} passContext
+   * @param {LH.Artifacts.NetworkRequest[]} networkRecords
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
-  async afterPass(passContext, loadData) {
+  async _getArtifact(passContext, networkRecords) {
     const fromDOM = await LinkElements.getLinkElementsInDOM(passContext);
-    const fromHeaders = LinkElements.getLinkElementsInHeaders(passContext, loadData);
+    const fromHeaders = await LinkElements.getLinkElementsInHeaders(passContext, networkRecords);
     const linkElements = fromDOM.concat(fromHeaders);
 
     for (const link of linkElements) {
@@ -147,6 +154,29 @@ class LinkElements extends Gatherer {
 
     return linkElements;
   }
+
+  /**
+   * @param {LH.Gatherer.PassContext} passContext
+   * @param {LH.Gatherer.LoadData} loadData
+   * @return {Promise<LH.Artifacts['LinkElements']>}
+   */
+  async afterPass(passContext, loadData) {
+    return await this._getArtifact(passContext, loadData.networkRecords);
+  }
+
+  /**
+   * @param {LH.Gatherer.FRTransitionalContext<'DevtoolsLog'>} passContext
+   * @return {Promise<LH.Artifacts['LinkElements']>}
+   */
+  async getArtifact(passContext) {
+    const context = {
+      computedCache: passContext.computedCache,
+      settings: passContext.settings,
+      options: {},
+    };
+    const records = await NetworkRecords.request(passContext.dependencies.DevtoolsLog, context);
+    return await this._getArtifact(passContext, records);
+  }
 }
 
 module.exports = LinkElements;
diff --git a/lighthouse-core/index.js b/lighthouse-core/index.js
index 1b27136c8a60..4c0acf298610 100644
--- a/lighthouse-core/index.js
+++ b/lighthouse-core/index.js
@@ -41,7 +41,8 @@ async function lighthouse(url, flags = {}, configJSON, userConnection) {
   log.setLevel(flags.logLevel);
 
   const config = generateConfig(configJSON, flags);
-  const options = {url, config};
+  const computedCache = new Map();
+  const options = {url, config, computedCache};
   const connection = userConnection || new ChromeProtocol(flags.port, flags.hostname);
 
   // kick off a lighthouse run
diff --git a/lighthouse-core/runner.js b/lighthouse-core/runner.js
index 1239345d61a2..62f5f00986fc 100644
--- a/lighthouse-core/runner.js
+++ b/lighthouse-core/runner.js
@@ -22,13 +22,14 @@ const generateReport = require('./report/report-generator.js').generateReport;
 const LHError = require('./lib/lh-error.js');
 
 /** @typedef {import('./gather/connections/connection.js')} Connection */
+/** @typedef {import('./lib/arbitrary-equality-map.js')} ArbitraryEqualityMap */
 /** @typedef {LH.Config.Config} Config */
 
 class Runner {
   /**
    * @template {LH.Config.Config | LH.Config.FRConfig} TConfig
    * @param {(runnerData: {requestedUrl: string, config: TConfig, driverMock?: Driver}) => Promise<LH.Artifacts>} gatherFn
-   * @param {{config: TConfig, url?: string, driverMock?: Driver}} runOpts
+   * @param {{config: TConfig, computedCache: Map<string, ArbitraryEqualityMap>, url?: string, driverMock?: Driver}} runOpts
    * @return {Promise<LH.RunnerResult|undefined>}
    */
   static async run(gatherFn, runOpts) {
@@ -100,7 +101,7 @@ class Runner {
         throw new Error('No audits to evaluate.');
       }
       const auditResultsById = await Runner._runAudits(settings, runOpts.config.audits, artifacts,
-          lighthouseRunWarnings);
+          lighthouseRunWarnings, runOpts.computedCache);
 
       // LHR construction phase
       const resultsStatus = {msg: 'Generating results...', id: 'lh:runner:generate'};
@@ -217,7 +218,7 @@ class Runner {
   /**
    * Establish connection, load page and collect all required artifacts
    * @param {string} requestedUrl
-   * @param {{config: Config, driverMock?: Driver}} runnerOpts
+   * @param {{config: Config, computedCache: Map<string, ArbitraryEqualityMap>, driverMock?: Driver}} runnerOpts
    * @param {Connection} connection
    * @return {Promise<LH.Artifacts>}
    */
@@ -230,6 +231,7 @@ class Runner {
       driver,
       requestedUrl,
       settings: runnerOpts.config.settings,
+      computedCache: runnerOpts.computedCache,
     };
     const artifacts = await GatherRunner.run(runnerOpts.config.passes, gatherOpts);
     return artifacts;
@@ -241,9 +243,10 @@ class Runner {
    * @param {Array<LH.Config.AuditDefn>} audits
    * @param {LH.Artifacts} artifacts
    * @param {Array<string | LH.IcuMessage>} runWarnings
+   * @param {Map<string, ArbitraryEqualityMap>} computedCache
    * @return {Promise<Record<string, LH.RawIcu<LH.Audit.Result>>>}
    */
-  static async _runAudits(settings, audits, artifacts, runWarnings) {
+  static async _runAudits(settings, audits, artifacts, runWarnings, computedCache) {
     const status = {msg: 'Analyzing and running audits...', id: 'lh:runner:auditing'};
     log.time(status);
 
@@ -267,7 +270,7 @@ class Runner {
     // Members of LH.Audit.Context that are shared across all audits.
     const sharedAuditContext = {
       settings,
-      computedCache: new Map(),
+      computedCache,
     };
 
     // Run each audit sequentially
diff --git a/types/gatherer.d.ts b/types/gatherer.d.ts
index 65562391feea..b1a26a39c93c 100644
--- a/types/gatherer.d.ts
+++ b/types/gatherer.d.ts
@@ -10,6 +10,7 @@ import _Simulator = require('../lighthouse-core/lib/dependency-graph/simulator/s
 import Driver = require('../lighthouse-core/gather/driver');
 import ExecutionContext = require('../lighthouse-core/gather/driver/execution-context');
 import Fetcher = require('../lighthouse-core/gather/fetcher');
+import ArbitraryEqualityMap = require('../lighthouse-core/lib/arbitrary-equality-map');
 
 declare global {
   module LH.Gatherer {
@@ -41,6 +42,8 @@ declare global {
       gatherMode: GatherMode;
       /** The connection to the page being analyzed. */
       driver: FRTransitionalDriver;
+      computedCache: Map<string, ArbitraryEqualityMap>;
+      settings: Config.Settings;
       /** The set of available dependencies requested by the current gatherer. */
       dependencies: TDependencies extends DefaultDependenciesKey ?
         {} :
@@ -54,11 +57,14 @@ declare global {
       driver: Driver;
       passConfig: Config.Pass
       settings: Config.Settings;
+      computedCache: Map<string, ArbitraryEqualityMap>
       /** Gatherers can push to this array to add top-level warnings to the LHR. */
       LighthouseRunWarnings: Array<string | IcuMessage>;
       baseArtifacts: BaseArtifacts;
     }
 
+    export type CompatibilityContext = PassContext | FRTransitionalContext;
+
     export interface LoadData {
       networkRecords: Array<Artifacts.NetworkRequest>;
       devtoolsLog: DevtoolsLog;

From 42e04ddcc8ab92d94d72693e0d47fb3ca3dd2772 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Fri, 30 Apr 2021 18:45:15 -0400
Subject: [PATCH 02/17] computed context

---
 lighthouse-core/audits/metrics.js                 |  2 +-
 lighthouse-core/audits/performance-budget.js      |  3 ++-
 lighthouse-core/audits/resource-summary.js        |  2 +-
 lighthouse-core/audits/timing-budget.js           |  3 ++-
 lighthouse-core/computed/computed-artifact.js     |  5 +++--
 lighthouse-core/computed/metrics/metric.js        |  6 +++---
 .../computed/metrics/timing-summary.js            | 15 ++++++++-------
 lighthouse-core/computed/resource-summary.js      | 12 ++++++------
 types/artifacts.d.ts                              |  1 +
 types/gatherer.d.ts                               |  4 ++++
 10 files changed, 31 insertions(+), 22 deletions(-)

diff --git a/lighthouse-core/audits/metrics.js b/lighthouse-core/audits/metrics.js
index fa839d300488..6f6942f093a6 100644
--- a/lighthouse-core/audits/metrics.js
+++ b/lighthouse-core/audits/metrics.js
@@ -44,7 +44,7 @@ class Metrics extends Audit {
     const trace = artifacts.traces[Audit.DEFAULT_PASS];
     const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
     const summary = await ComputedTimingSummary
-      .request({trace, devtoolsLog}, context);
+      .request({trace, devtoolsLog, settings: artifacts.settings}, context);
     const metrics = summary.metrics;
     const debugInfo = summary.debugInfo;
 
diff --git a/lighthouse-core/audits/performance-budget.js b/lighthouse-core/audits/performance-budget.js
index c8e68a4da46b..d41b874cdd28 100644
--- a/lighthouse-core/audits/performance-budget.js
+++ b/lighthouse-core/audits/performance-budget.js
@@ -120,7 +120,8 @@ class ResourceBudget extends Audit {
    */
   static async audit(artifacts, context) {
     const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
-    const summary = await ResourceSummary.request({devtoolsLog, URL: artifacts.URL}, context);
+    const data = {devtoolsLog, URL: artifacts.URL, settings: artifacts.settings};
+    const summary = await ResourceSummary.request(data, context);
     const mainResource = await MainResource.request({URL: artifacts.URL, devtoolsLog}, context);
     const budget = Budget.getMatchingBudget(context.settings.budgets, mainResource.url);
 
diff --git a/lighthouse-core/audits/resource-summary.js b/lighthouse-core/audits/resource-summary.js
index e41da0885c96..9fc4d63ca643 100644
--- a/lighthouse-core/audits/resource-summary.js
+++ b/lighthouse-core/audits/resource-summary.js
@@ -45,7 +45,7 @@ class ResourceSummary extends Audit {
   static async audit(artifacts, context) {
     const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
     const summary = await ComputedResourceSummary
-      .request({devtoolsLog, URL: artifacts.URL}, context);
+      .request({devtoolsLog, URL: artifacts.URL, settings: artifacts.settings}, context);
 
     /** @type {LH.Audit.Details.Table['headings']} */
     const headings = [
diff --git a/lighthouse-core/audits/timing-budget.js b/lighthouse-core/audits/timing-budget.js
index 950c648d5c5f..4be90b209142 100644
--- a/lighthouse-core/audits/timing-budget.js
+++ b/lighthouse-core/audits/timing-budget.js
@@ -143,7 +143,8 @@ class TimingBudget extends Audit {
     const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
     const trace = artifacts.traces[Audit.DEFAULT_PASS];
     const mainResource = await MainResource.request({URL: artifacts.URL, devtoolsLog}, context);
-    const summary = (await TimingSummary.request({trace, devtoolsLog}, context)).metrics;
+    const data = {trace, devtoolsLog, settings: artifacts.settings};
+    const summary = (await TimingSummary.request(data, context)).metrics;
     const budget = Budget.getMatchingBudget(context.settings.budgets, mainResource.url);
 
     if (!budget) {
diff --git a/lighthouse-core/computed/computed-artifact.js b/lighthouse-core/computed/computed-artifact.js
index 268fee9d7157..233dcb231bec 100644
--- a/lighthouse-core/computed/computed-artifact.js
+++ b/lighthouse-core/computed/computed-artifact.js
@@ -8,10 +8,11 @@
 const ArbitraryEqualityMap = require('../lib/arbitrary-equality-map.js');
 const log = require('lighthouse-logger');
 
+
 /**
  * Decorate computableArtifact with a caching `request()` method which will
  * automatically call `computableArtifact.compute_()` under the hood.
- * @template {{name: string, compute_(artifacts: unknown, context: LH.Audit.Context): Promise<unknown>}} C
+ * @template {{name: string, compute_(artifacts: unknown, context: LH.Gatherer.ComputedContext): Promise<unknown>}} C
  * @param {C} computableArtifact
  */
 function makeComputedArtifact(computableArtifact) {
@@ -21,7 +22,7 @@ function makeComputedArtifact(computableArtifact) {
   /**
    * Return an automatically cached result from the computed artifact.
    * @param {FirstParamType<C['compute_']>} artifacts
-   * @param {LH.Audit.Context} context
+   * @param {LH.Gatherer.ComputedContext} context
    * @return {ReturnType<C['compute_']>}
    */
   const request = (artifacts, context) => {
diff --git a/lighthouse-core/computed/metrics/metric.js b/lighthouse-core/computed/metrics/metric.js
index f0ff896e908f..85a6115671b5 100644
--- a/lighthouse-core/computed/metrics/metric.js
+++ b/lighthouse-core/computed/metrics/metric.js
@@ -23,7 +23,7 @@ class ComputedMetric {
 
   /**
    * @param {LH.Artifacts.MetricComputationData} data
-   * @param {LH.Audit.Context} context
+   * @param {LH.Gatherer.ComputedContext} context
    * @return {Promise<LH.Artifacts.LanternMetric>}
    */
   static computeSimulatedMetric(data, context) { // eslint-disable-line no-unused-vars
@@ -32,7 +32,7 @@ class ComputedMetric {
 
   /**
    * @param {LH.Artifacts.MetricComputationData} data
-   * @param {LH.Audit.Context} context
+   * @param {LH.Gatherer.ComputedContext} context
    * @return {Promise<LH.Artifacts.Metric>}
    */
   static computeObservedMetric(data, context) { // eslint-disable-line no-unused-vars
@@ -41,7 +41,7 @@ class ComputedMetric {
 
   /**
    * @param {LH.Artifacts.MetricComputationDataInput} data
-   * @param {LH.Audit.Context} context
+   * @param {LH.Gatherer.ComputedContext} context
    * @return {Promise<LH.Artifacts.LanternMetric|LH.Artifacts.Metric>}
    */
   static async compute_(data, context) {
diff --git a/lighthouse-core/computed/metrics/timing-summary.js b/lighthouse-core/computed/metrics/timing-summary.js
index 3e90253e2deb..0cd390b1bab3 100644
--- a/lighthouse-core/computed/metrics/timing-summary.js
+++ b/lighthouse-core/computed/metrics/timing-summary.js
@@ -27,15 +27,16 @@ class TimingSummary {
   /**
      * @param {LH.Trace} trace
      * @param {LH.DevtoolsLog} devtoolsLog
-     * @param {LH.Audit.Context} context
+     * @param {LH.Config.Settings} settings
+     * @param {LH.Gatherer.ComputedContext} context
      * @return {Promise<{metrics: LH.Artifacts.TimingSummary, debugInfo: Record<string,boolean>}>}
      */
-  static async summarize(trace, devtoolsLog, context) {
-    const metricComputationData = {trace, devtoolsLog, settings: context.settings};
+  static async summarize(trace, devtoolsLog, settings, context) {
+    const metricComputationData = {trace, devtoolsLog, settings};
     /**
      * @template TArtifacts
      * @template TReturn
-     * @param {{request: (artifact: TArtifacts, context: LH.Audit.Context) => Promise<TReturn>}} Artifact
+     * @param {{request: (artifact: TArtifacts, context: LH.Gatherer.ComputedContext) => Promise<TReturn>}} Artifact
      * @param {TArtifacts} artifact
      * @return {Promise<TReturn|undefined>}
      */
@@ -141,12 +142,12 @@ class TimingSummary {
     return {metrics, debugInfo};
   }
   /**
-   * @param {{trace: LH.Trace, devtoolsLog: LH.DevtoolsLog}} data
-   * @param {LH.Audit.Context} context
+   * @param {{trace: LH.Trace, devtoolsLog: LH.DevtoolsLog, settings: LH.Config.Settings}} data
+   * @param {LH.Gatherer.ComputedContext} context
    * @return {Promise<{metrics: LH.Artifacts.TimingSummary, debugInfo: Record<string,boolean>}>}
    */
   static async compute_(data, context) {
-    return TimingSummary.summarize(data.trace, data.devtoolsLog, context);
+    return TimingSummary.summarize(data.trace, data.devtoolsLog, data.settings, context);
   }
 }
 
diff --git a/lighthouse-core/computed/resource-summary.js b/lighthouse-core/computed/resource-summary.js
index bc3536ce8be0..81ee5dc9b854 100644
--- a/lighthouse-core/computed/resource-summary.js
+++ b/lighthouse-core/computed/resource-summary.js
@@ -37,10 +37,10 @@ class ResourceSummary {
   /**
    * @param {Array<LH.Artifacts.NetworkRequest>} networkRecords
    * @param {string} mainResourceURL
-   * @param {LH.Audit.Context} context
+   * @param {LH.Config.Settings} settings
    * @return {Record<LH.Budget.ResourceType, ResourceEntry>}
    */
-  static summarize(networkRecords, mainResourceURL, context) {
+  static summarize(networkRecords, mainResourceURL, settings) {
     /** @type {Record<LH.Budget.ResourceType, ResourceEntry>} */
     const resourceSummary = {
       'stylesheet': {count: 0, resourceSize: 0, transferSize: 0},
@@ -53,7 +53,7 @@ class ResourceSummary {
       'total': {count: 0, resourceSize: 0, transferSize: 0},
       'third-party': {count: 0, resourceSize: 0, transferSize: 0},
     };
-    const budget = Budget.getMatchingBudget(context.settings.budgets, mainResourceURL);
+    const budget = Budget.getMatchingBudget(settings.budgets, mainResourceURL);
     /** @type {ReadonlyArray<string>} */
     let firstPartyHosts = [];
     if (budget && budget.options && budget.options.firstPartyHostnames) {
@@ -102,8 +102,8 @@ class ResourceSummary {
   }
 
   /**
-   * @param {{URL: LH.Artifacts['URL'], devtoolsLog: LH.DevtoolsLog}} data
-   * @param {LH.Audit.Context} context
+   * @param {{URL: LH.Artifacts['URL'], devtoolsLog: LH.DevtoolsLog, settings: LH.Config.Settings}} data
+   * @param {LH.Gatherer.ComputedContext} context
    * @return {Promise<Record<LH.Budget.ResourceType,ResourceEntry>>}
    */
   static async compute_(data, context) {
@@ -111,7 +111,7 @@ class ResourceSummary {
       NetworkRecords.request(data.devtoolsLog, context),
       MainResource.request(data, context),
     ]);
-    return ResourceSummary.summarize(networkRecords, mainResource.url, context);
+    return ResourceSummary.summarize(networkRecords, mainResource.url, data.settings);
   }
 }
 
diff --git a/types/artifacts.d.ts b/types/artifacts.d.ts
index 073da753fe78..98ef599c0fa0 100644
--- a/types/artifacts.d.ts
+++ b/types/artifacts.d.ts
@@ -9,6 +9,7 @@ import _LanternSimulator = require('../lighthouse-core/lib/dependency-graph/simu
 import _NetworkRequest = require('../lighthouse-core/lib/network-request.js');
 import speedline = require('speedline-core');
 import TextSourceMap = require('../lighthouse-core/lib/cdt/generated/SourceMap.js');
+import ArbitraryEqualityMap = require('../lighthouse-core/lib/arbitrary-equality-map.js');
 
 type _TaskNode = import('../lighthouse-core/lib/tracehouse/main-thread-tasks.js').TaskNode;
 
diff --git a/types/gatherer.d.ts b/types/gatherer.d.ts
index b1a26a39c93c..c8b0e45aa603 100644
--- a/types/gatherer.d.ts
+++ b/types/gatherer.d.ts
@@ -63,6 +63,10 @@ declare global {
       baseArtifacts: BaseArtifacts;
     }
 
+    export type ComputedContext = Immutable<{
+      computedCache: Map<string, ArbitraryEqualityMap>;
+    }>;
+
     export type CompatibilityContext = PassContext | FRTransitionalContext;
 
     export interface LoadData {

From 6e2c770febbdb2ddcbd95bbe32e5a26184fe16f2 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Mon, 3 May 2021 14:48:58 -0400
Subject: [PATCH 03/17] Revert "computed context"

This reverts commit 42e04ddcc8ab92d94d72693e0d47fb3ca3dd2772.
---
 lighthouse-core/audits/metrics.js                 |  2 +-
 lighthouse-core/audits/performance-budget.js      |  3 +--
 lighthouse-core/audits/resource-summary.js        |  2 +-
 lighthouse-core/audits/timing-budget.js           |  3 +--
 lighthouse-core/computed/computed-artifact.js     |  5 ++---
 lighthouse-core/computed/metrics/metric.js        |  6 +++---
 .../computed/metrics/timing-summary.js            | 15 +++++++--------
 lighthouse-core/computed/resource-summary.js      | 12 ++++++------
 types/artifacts.d.ts                              |  1 -
 types/gatherer.d.ts                               |  4 ----
 10 files changed, 22 insertions(+), 31 deletions(-)

diff --git a/lighthouse-core/audits/metrics.js b/lighthouse-core/audits/metrics.js
index 6f6942f093a6..fa839d300488 100644
--- a/lighthouse-core/audits/metrics.js
+++ b/lighthouse-core/audits/metrics.js
@@ -44,7 +44,7 @@ class Metrics extends Audit {
     const trace = artifacts.traces[Audit.DEFAULT_PASS];
     const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
     const summary = await ComputedTimingSummary
-      .request({trace, devtoolsLog, settings: artifacts.settings}, context);
+      .request({trace, devtoolsLog}, context);
     const metrics = summary.metrics;
     const debugInfo = summary.debugInfo;
 
diff --git a/lighthouse-core/audits/performance-budget.js b/lighthouse-core/audits/performance-budget.js
index d41b874cdd28..c8e68a4da46b 100644
--- a/lighthouse-core/audits/performance-budget.js
+++ b/lighthouse-core/audits/performance-budget.js
@@ -120,8 +120,7 @@ class ResourceBudget extends Audit {
    */
   static async audit(artifacts, context) {
     const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
-    const data = {devtoolsLog, URL: artifacts.URL, settings: artifacts.settings};
-    const summary = await ResourceSummary.request(data, context);
+    const summary = await ResourceSummary.request({devtoolsLog, URL: artifacts.URL}, context);
     const mainResource = await MainResource.request({URL: artifacts.URL, devtoolsLog}, context);
     const budget = Budget.getMatchingBudget(context.settings.budgets, mainResource.url);
 
diff --git a/lighthouse-core/audits/resource-summary.js b/lighthouse-core/audits/resource-summary.js
index 9fc4d63ca643..e41da0885c96 100644
--- a/lighthouse-core/audits/resource-summary.js
+++ b/lighthouse-core/audits/resource-summary.js
@@ -45,7 +45,7 @@ class ResourceSummary extends Audit {
   static async audit(artifacts, context) {
     const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
     const summary = await ComputedResourceSummary
-      .request({devtoolsLog, URL: artifacts.URL, settings: artifacts.settings}, context);
+      .request({devtoolsLog, URL: artifacts.URL}, context);
 
     /** @type {LH.Audit.Details.Table['headings']} */
     const headings = [
diff --git a/lighthouse-core/audits/timing-budget.js b/lighthouse-core/audits/timing-budget.js
index 4be90b209142..950c648d5c5f 100644
--- a/lighthouse-core/audits/timing-budget.js
+++ b/lighthouse-core/audits/timing-budget.js
@@ -143,8 +143,7 @@ class TimingBudget extends Audit {
     const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
     const trace = artifacts.traces[Audit.DEFAULT_PASS];
     const mainResource = await MainResource.request({URL: artifacts.URL, devtoolsLog}, context);
-    const data = {trace, devtoolsLog, settings: artifacts.settings};
-    const summary = (await TimingSummary.request(data, context)).metrics;
+    const summary = (await TimingSummary.request({trace, devtoolsLog}, context)).metrics;
     const budget = Budget.getMatchingBudget(context.settings.budgets, mainResource.url);
 
     if (!budget) {
diff --git a/lighthouse-core/computed/computed-artifact.js b/lighthouse-core/computed/computed-artifact.js
index 233dcb231bec..268fee9d7157 100644
--- a/lighthouse-core/computed/computed-artifact.js
+++ b/lighthouse-core/computed/computed-artifact.js
@@ -8,11 +8,10 @@
 const ArbitraryEqualityMap = require('../lib/arbitrary-equality-map.js');
 const log = require('lighthouse-logger');
 
-
 /**
  * Decorate computableArtifact with a caching `request()` method which will
  * automatically call `computableArtifact.compute_()` under the hood.
- * @template {{name: string, compute_(artifacts: unknown, context: LH.Gatherer.ComputedContext): Promise<unknown>}} C
+ * @template {{name: string, compute_(artifacts: unknown, context: LH.Audit.Context): Promise<unknown>}} C
  * @param {C} computableArtifact
  */
 function makeComputedArtifact(computableArtifact) {
@@ -22,7 +21,7 @@ function makeComputedArtifact(computableArtifact) {
   /**
    * Return an automatically cached result from the computed artifact.
    * @param {FirstParamType<C['compute_']>} artifacts
-   * @param {LH.Gatherer.ComputedContext} context
+   * @param {LH.Audit.Context} context
    * @return {ReturnType<C['compute_']>}
    */
   const request = (artifacts, context) => {
diff --git a/lighthouse-core/computed/metrics/metric.js b/lighthouse-core/computed/metrics/metric.js
index 85a6115671b5..f0ff896e908f 100644
--- a/lighthouse-core/computed/metrics/metric.js
+++ b/lighthouse-core/computed/metrics/metric.js
@@ -23,7 +23,7 @@ class ComputedMetric {
 
   /**
    * @param {LH.Artifacts.MetricComputationData} data
-   * @param {LH.Gatherer.ComputedContext} context
+   * @param {LH.Audit.Context} context
    * @return {Promise<LH.Artifacts.LanternMetric>}
    */
   static computeSimulatedMetric(data, context) { // eslint-disable-line no-unused-vars
@@ -32,7 +32,7 @@ class ComputedMetric {
 
   /**
    * @param {LH.Artifacts.MetricComputationData} data
-   * @param {LH.Gatherer.ComputedContext} context
+   * @param {LH.Audit.Context} context
    * @return {Promise<LH.Artifacts.Metric>}
    */
   static computeObservedMetric(data, context) { // eslint-disable-line no-unused-vars
@@ -41,7 +41,7 @@ class ComputedMetric {
 
   /**
    * @param {LH.Artifacts.MetricComputationDataInput} data
-   * @param {LH.Gatherer.ComputedContext} context
+   * @param {LH.Audit.Context} context
    * @return {Promise<LH.Artifacts.LanternMetric|LH.Artifacts.Metric>}
    */
   static async compute_(data, context) {
diff --git a/lighthouse-core/computed/metrics/timing-summary.js b/lighthouse-core/computed/metrics/timing-summary.js
index 0cd390b1bab3..3e90253e2deb 100644
--- a/lighthouse-core/computed/metrics/timing-summary.js
+++ b/lighthouse-core/computed/metrics/timing-summary.js
@@ -27,16 +27,15 @@ class TimingSummary {
   /**
      * @param {LH.Trace} trace
      * @param {LH.DevtoolsLog} devtoolsLog
-     * @param {LH.Config.Settings} settings
-     * @param {LH.Gatherer.ComputedContext} context
+     * @param {LH.Audit.Context} context
      * @return {Promise<{metrics: LH.Artifacts.TimingSummary, debugInfo: Record<string,boolean>}>}
      */
-  static async summarize(trace, devtoolsLog, settings, context) {
-    const metricComputationData = {trace, devtoolsLog, settings};
+  static async summarize(trace, devtoolsLog, context) {
+    const metricComputationData = {trace, devtoolsLog, settings: context.settings};
     /**
      * @template TArtifacts
      * @template TReturn
-     * @param {{request: (artifact: TArtifacts, context: LH.Gatherer.ComputedContext) => Promise<TReturn>}} Artifact
+     * @param {{request: (artifact: TArtifacts, context: LH.Audit.Context) => Promise<TReturn>}} Artifact
      * @param {TArtifacts} artifact
      * @return {Promise<TReturn|undefined>}
      */
@@ -142,12 +141,12 @@ class TimingSummary {
     return {metrics, debugInfo};
   }
   /**
-   * @param {{trace: LH.Trace, devtoolsLog: LH.DevtoolsLog, settings: LH.Config.Settings}} data
-   * @param {LH.Gatherer.ComputedContext} context
+   * @param {{trace: LH.Trace, devtoolsLog: LH.DevtoolsLog}} data
+   * @param {LH.Audit.Context} context
    * @return {Promise<{metrics: LH.Artifacts.TimingSummary, debugInfo: Record<string,boolean>}>}
    */
   static async compute_(data, context) {
-    return TimingSummary.summarize(data.trace, data.devtoolsLog, data.settings, context);
+    return TimingSummary.summarize(data.trace, data.devtoolsLog, context);
   }
 }
 
diff --git a/lighthouse-core/computed/resource-summary.js b/lighthouse-core/computed/resource-summary.js
index 81ee5dc9b854..bc3536ce8be0 100644
--- a/lighthouse-core/computed/resource-summary.js
+++ b/lighthouse-core/computed/resource-summary.js
@@ -37,10 +37,10 @@ class ResourceSummary {
   /**
    * @param {Array<LH.Artifacts.NetworkRequest>} networkRecords
    * @param {string} mainResourceURL
-   * @param {LH.Config.Settings} settings
+   * @param {LH.Audit.Context} context
    * @return {Record<LH.Budget.ResourceType, ResourceEntry>}
    */
-  static summarize(networkRecords, mainResourceURL, settings) {
+  static summarize(networkRecords, mainResourceURL, context) {
     /** @type {Record<LH.Budget.ResourceType, ResourceEntry>} */
     const resourceSummary = {
       'stylesheet': {count: 0, resourceSize: 0, transferSize: 0},
@@ -53,7 +53,7 @@ class ResourceSummary {
       'total': {count: 0, resourceSize: 0, transferSize: 0},
       'third-party': {count: 0, resourceSize: 0, transferSize: 0},
     };
-    const budget = Budget.getMatchingBudget(settings.budgets, mainResourceURL);
+    const budget = Budget.getMatchingBudget(context.settings.budgets, mainResourceURL);
     /** @type {ReadonlyArray<string>} */
     let firstPartyHosts = [];
     if (budget && budget.options && budget.options.firstPartyHostnames) {
@@ -102,8 +102,8 @@ class ResourceSummary {
   }
 
   /**
-   * @param {{URL: LH.Artifacts['URL'], devtoolsLog: LH.DevtoolsLog, settings: LH.Config.Settings}} data
-   * @param {LH.Gatherer.ComputedContext} context
+   * @param {{URL: LH.Artifacts['URL'], devtoolsLog: LH.DevtoolsLog}} data
+   * @param {LH.Audit.Context} context
    * @return {Promise<Record<LH.Budget.ResourceType,ResourceEntry>>}
    */
   static async compute_(data, context) {
@@ -111,7 +111,7 @@ class ResourceSummary {
       NetworkRecords.request(data.devtoolsLog, context),
       MainResource.request(data, context),
     ]);
-    return ResourceSummary.summarize(networkRecords, mainResource.url, data.settings);
+    return ResourceSummary.summarize(networkRecords, mainResource.url, context);
   }
 }
 
diff --git a/types/artifacts.d.ts b/types/artifacts.d.ts
index 98ef599c0fa0..073da753fe78 100644
--- a/types/artifacts.d.ts
+++ b/types/artifacts.d.ts
@@ -9,7 +9,6 @@ import _LanternSimulator = require('../lighthouse-core/lib/dependency-graph/simu
 import _NetworkRequest = require('../lighthouse-core/lib/network-request.js');
 import speedline = require('speedline-core');
 import TextSourceMap = require('../lighthouse-core/lib/cdt/generated/SourceMap.js');
-import ArbitraryEqualityMap = require('../lighthouse-core/lib/arbitrary-equality-map.js');
 
 type _TaskNode = import('../lighthouse-core/lib/tracehouse/main-thread-tasks.js').TaskNode;
 
diff --git a/types/gatherer.d.ts b/types/gatherer.d.ts
index c8b0e45aa603..b1a26a39c93c 100644
--- a/types/gatherer.d.ts
+++ b/types/gatherer.d.ts
@@ -63,10 +63,6 @@ declare global {
       baseArtifacts: BaseArtifacts;
     }
 
-    export type ComputedContext = Immutable<{
-      computedCache: Map<string, ArbitraryEqualityMap>;
-    }>;
-
     export type CompatibilityContext = PassContext | FRTransitionalContext;
 
     export interface LoadData {

From b43616a99591272b4a0e400f7ed02ea7cbfd09c3 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Mon, 3 May 2021 16:48:47 -0400
Subject: [PATCH 04/17] resolve types

---
 lighthouse-core/fraggle-rock/gather/navigation-runner.js | 1 +
 lighthouse-core/fraggle-rock/gather/runner-helpers.js    | 1 +
 lighthouse-core/fraggle-rock/gather/snapshot-runner.js   | 1 +
 lighthouse-core/fraggle-rock/gather/timespan-runner.js   | 1 +
 lighthouse-core/gather/gather-runner.js                  | 7 +------
 lighthouse-core/gather/gatherers/link-elements.js        | 7 +------
 types/gatherer.d.ts                                      | 2 +-
 7 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/lighthouse-core/fraggle-rock/gather/navigation-runner.js b/lighthouse-core/fraggle-rock/gather/navigation-runner.js
index 5609b5e9af34..93da919372b8 100644
--- a/lighthouse-core/fraggle-rock/gather/navigation-runner.js
+++ b/lighthouse-core/fraggle-rock/gather/navigation-runner.js
@@ -137,6 +137,7 @@ async function navigation(options) {
     {
       url: requestedUrl,
       config,
+      computedCache: new Map(),
     }
   );
 }
diff --git a/lighthouse-core/fraggle-rock/gather/runner-helpers.js b/lighthouse-core/fraggle-rock/gather/runner-helpers.js
index 0d933bacccc1..f360f3a5843d 100644
--- a/lighthouse-core/fraggle-rock/gather/runner-helpers.js
+++ b/lighthouse-core/fraggle-rock/gather/runner-helpers.js
@@ -76,6 +76,7 @@ async function collectPhaseArtifacts(options) {
         gatherMode,
         driver,
         dependencies,
+        computedCache: new Map(),
       });
     });
 
diff --git a/lighthouse-core/fraggle-rock/gather/snapshot-runner.js b/lighthouse-core/fraggle-rock/gather/snapshot-runner.js
index b3fe26744cd2..30ac7dabf0fa 100644
--- a/lighthouse-core/fraggle-rock/gather/snapshot-runner.js
+++ b/lighthouse-core/fraggle-rock/gather/snapshot-runner.js
@@ -45,6 +45,7 @@ async function snapshot(options) {
     {
       url,
       config,
+      computedCache: new Map(),
     }
   );
 }
diff --git a/lighthouse-core/fraggle-rock/gather/timespan-runner.js b/lighthouse-core/fraggle-rock/gather/timespan-runner.js
index bec25ba1cbb8..e36ea00c2152 100644
--- a/lighthouse-core/fraggle-rock/gather/timespan-runner.js
+++ b/lighthouse-core/fraggle-rock/gather/timespan-runner.js
@@ -51,6 +51,7 @@ async function startTimespan(options) {
         {
           url: finalUrl,
           config,
+          computedCache: new Map(),
         }
       );
     },
diff --git a/lighthouse-core/gather/gather-runner.js b/lighthouse-core/gather/gather-runner.js
index 11495771c80f..73c53cae12ef 100644
--- a/lighthouse-core/gather/gather-runner.js
+++ b/lighthouse-core/gather/gather-runner.js
@@ -478,12 +478,7 @@ class GatherRunner {
     };
     log.time(status);
     const devtoolsLog = driver.endDevtoolsLog();
-    const context = {
-      computedCache: passContext.computedCache,
-      settings: passContext.settings,
-      options: {},
-    };
-    const networkRecords = await NetworkRecords.request(devtoolsLog, context);
+    const networkRecords = await NetworkRecords.request(devtoolsLog, passContext);
     log.timeEnd(status);
 
     return {
diff --git a/lighthouse-core/gather/gatherers/link-elements.js b/lighthouse-core/gather/gatherers/link-elements.js
index 50f4a25ddc1c..f3732fff4a04 100644
--- a/lighthouse-core/gather/gatherers/link-elements.js
+++ b/lighthouse-core/gather/gatherers/link-elements.js
@@ -169,12 +169,7 @@ class LinkElements extends FRGatherer {
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
   async getArtifact(passContext) {
-    const context = {
-      computedCache: passContext.computedCache,
-      settings: passContext.settings,
-      options: {},
-    };
-    const records = await NetworkRecords.request(passContext.dependencies.DevtoolsLog, context);
+    const records = await NetworkRecords.request(passContext.dependencies.DevtoolsLog, passContext);
     return await this._getArtifact(passContext, records);
   }
 }
diff --git a/types/gatherer.d.ts b/types/gatherer.d.ts
index b1a26a39c93c..f712954074b1 100644
--- a/types/gatherer.d.ts
+++ b/types/gatherer.d.ts
@@ -42,8 +42,8 @@ declare global {
       gatherMode: GatherMode;
       /** The connection to the page being analyzed. */
       driver: FRTransitionalDriver;
+      /** The cached results of computed artifacts. */
       computedCache: Map<string, ArbitraryEqualityMap>;
-      settings: Config.Settings;
       /** The set of available dependencies requested by the current gatherer. */
       dependencies: TDependencies extends DefaultDependenciesKey ?
         {} :

From f3b0a19216784df56dd46d281be7471ad9f0a790 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Mon, 3 May 2021 17:13:06 -0400
Subject: [PATCH 05/17] rm compatibility context

---
 lighthouse-core/gather/gather-runner.js           | 1 +
 lighthouse-core/gather/gatherers/link-elements.js | 8 ++++----
 types/gatherer.d.ts                               | 3 +--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/lighthouse-core/gather/gather-runner.js b/lighthouse-core/gather/gather-runner.js
index 73c53cae12ef..ea666b514390 100644
--- a/lighthouse-core/gather/gather-runner.js
+++ b/lighthouse-core/gather/gather-runner.js
@@ -740,6 +740,7 @@ class GatherRunner {
           baseArtifacts,
           computedCache: options.computedCache,
           LighthouseRunWarnings: baseArtifacts.LighthouseRunWarnings,
+          dependencies: {},
         };
         const passResults = await GatherRunner.runPass(passContext);
         Object.assign(artifacts, passResults.artifacts);
diff --git a/lighthouse-core/gather/gatherers/link-elements.js b/lighthouse-core/gather/gatherers/link-elements.js
index f3732fff4a04..b3110a6cca16 100644
--- a/lighthouse-core/gather/gatherers/link-elements.js
+++ b/lighthouse-core/gather/gatherers/link-elements.js
@@ -89,7 +89,7 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.CompatibilityContext} passContext
+   * @param {LH.Gatherer.FRTransitionalContext} passContext
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
   static getLinkElementsInDOM(passContext) {
@@ -106,7 +106,7 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.CompatibilityContext} passContext
+   * @param {LH.Gatherer.FRTransitionalContext} passContext
    * @param {LH.Artifacts.NetworkRequest[]} networkRecords
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
@@ -138,7 +138,7 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.CompatibilityContext} passContext
+   * @param {LH.Gatherer.FRTransitionalContext} passContext
    * @param {LH.Artifacts.NetworkRequest[]} networkRecords
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
@@ -156,7 +156,7 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.PassContext} passContext
+   * @param {LH.Gatherer.FRTransitionalContext} passContext
    * @param {LH.Gatherer.LoadData} loadData
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
diff --git a/types/gatherer.d.ts b/types/gatherer.d.ts
index f712954074b1..ccb401347782 100644
--- a/types/gatherer.d.ts
+++ b/types/gatherer.d.ts
@@ -61,10 +61,9 @@ declare global {
       /** Gatherers can push to this array to add top-level warnings to the LHR. */
       LighthouseRunWarnings: Array<string | IcuMessage>;
       baseArtifacts: BaseArtifacts;
+      dependencies: {};
     }
 
-    export type CompatibilityContext = PassContext | FRTransitionalContext;
-
     export interface LoadData {
       networkRecords: Array<Artifacts.NetworkRequest>;
       devtoolsLog: DevtoolsLog;

From cf076cfb8191d41bf1bb77568306b66b294715ec Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Mon, 3 May 2021 17:42:42 -0400
Subject: [PATCH 06/17] gather-runner-test

---
 .../test/gather/gather-runner-test.js         | 39 +++++++++++++------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/lighthouse-core/test/gather/gather-runner-test.js b/lighthouse-core/test/gather/gather-runner-test.js
index e42e47371048..564dfb14ef82 100644
--- a/lighthouse-core/test/gather/gather-runner-test.js
+++ b/lighthouse-core/test/gather/gather-runner-test.js
@@ -207,7 +207,7 @@ describe('GatherRunner', function() {
     const requestedUrl = 'https://example.com';
     const driver = fakeDriver;
     const config = makeConfig({passes: []});
-    const options = {requestedUrl, driver, settings: config.settings};
+    const options = {requestedUrl, driver, settings: config.settings, computedCache: new Map()};
 
     const results = await GatherRunner.run(config.passes, options);
     expect(Number.isFinite(results.BenchmarkIndex)).toBeTruthy();
@@ -217,7 +217,7 @@ describe('GatherRunner', function() {
     const requestedUrl = 'https://example.com';
     const driver = fakeDriver;
     const config = makeConfig({passes: []});
-    const options = {requestedUrl, driver, settings: config.settings};
+    const options = {requestedUrl, driver, settings: config.settings, computedCache: new Map()};
 
     const results = await GatherRunner.run(config.passes, options);
     expect(results.HostUserAgent).toEqual(fakeDriver.protocolGetVersionResponse.userAgent);
@@ -228,7 +228,7 @@ describe('GatherRunner', function() {
     const requestedUrl = 'https://example.com';
     const driver = fakeDriver;
     const config = makeConfig({passes: [{passName: 'defaultPass'}]});
-    const options = {requestedUrl, driver, settings: config.settings};
+    const options = {requestedUrl, driver, settings: config.settings, computedCache: new Map()};
 
     const results = await GatherRunner.run(config.passes, options);
     expect(results.NetworkUserAgent).toContain('Mozilla');
@@ -243,7 +243,7 @@ describe('GatherRunner', function() {
       },
     });
     const config = makeConfig({passes: [{passName: 'defaultPass'}]});
-    const options = {requestedUrl, driver, settings: config.settings};
+    const options = {requestedUrl, driver, settings: config.settings, computedCache: new Map()};
 
     return GatherRunner.run(config.passes, options).then(artifacts => {
       assert.deepStrictEqual(artifacts.URL, {requestedUrl, finalUrl},
@@ -270,7 +270,7 @@ describe('GatherRunner', function() {
           passes: [],
           settings: {},
         });
-        const options = {requestedUrl, driver, settings: config.settings};
+        const options = {requestedUrl, driver, settings: config.settings, computedCache: new Map()};
 
         const results = await GatherRunner.run(config.passes, options);
         expect(results.HostFormFactor).toBe(expectedValue);
@@ -480,6 +480,7 @@ describe('GatherRunner', function() {
       passConfig,
       settings,
       baseArtifacts: await GatherRunner.initializeBaseArtifacts({driver, settings, requestedUrl}),
+      computedCache: new Map(),
     };
 
     const storage = jest.requireMock('../../gather/driver/storage.js');
@@ -512,6 +513,7 @@ describe('GatherRunner', function() {
       driver,
       requestedUrl,
       settings: config.settings,
+      computedCache: new Map(),
     };
 
     const artifacts = await GatherRunner.run(config.passes, options);
@@ -546,6 +548,7 @@ describe('GatherRunner', function() {
       driver,
       requestedUrl,
       settings: config.settings,
+      computedCache: new Map(),
     };
 
     const artifacts = await GatherRunner.run(config.passes, options);
@@ -586,6 +589,7 @@ describe('GatherRunner', function() {
       driver,
       requestedUrl,
       settings: config.settings,
+      computedCache: new Map(),
     };
 
     const artifacts = await GatherRunner.run(config.passes, options);
@@ -744,7 +748,8 @@ describe('GatherRunner', function() {
       ],
     };
 
-    return GatherRunner.endRecording({url, driver, passConfig}).then(passData => {
+    const passContext = {url, driver, passConfig, computedCache: new Map()};
+    return GatherRunner.endRecording(passContext).then(passData => {
       assert.equal(calledTrace, true);
       assert.equal(passData.trace, fakeTraceData);
     });
@@ -769,7 +774,7 @@ describe('GatherRunner', function() {
     };
     const settings = {};
 
-    await GatherRunner.beginRecording({driver, passConfig, settings});
+    await GatherRunner.beginRecording({driver, passConfig, settings, computedCache: new Map()});
     assert.equal(calledDevtoolsLogCollect, true);
   });
 
@@ -793,7 +798,8 @@ describe('GatherRunner', function() {
       ],
     };
 
-    return GatherRunner.endRecording({url, driver, passConfig}).then(passData => {
+    const passContext = {url, driver, passConfig, computedCache: new Map()};
+    return GatherRunner.endRecording(passContext).then(passData => {
       assert.equal(calledDevtoolsLogCollect, true);
       assert.strictEqual(passData.devtoolsLog[0], fakeDevtoolsMessage);
     });
@@ -823,7 +829,8 @@ describe('GatherRunner', function() {
     const gathererResults = {
       TestGatherer: [],
     };
-    await GatherRunner.afterPass({url, driver, passConfig}, {}, gathererResults);
+    const passContext = {url, driver, passConfig, computedCache: new Map()};
+    await GatherRunner.afterPass(passContext, {}, gathererResults);
     // One time for the afterPass of ScrollMcScrolly, two times for the resets of the two gatherers.
     expect(scrollToSpy.mock.calls).toEqual([
       [{x: 1000, y: 1000}],
@@ -855,6 +862,7 @@ describe('GatherRunner', function() {
       driver: fakeDriver,
       requestedUrl: 'https://example.com',
       settings: config.settings,
+      computedCache: new Map(),
     }).then(_ => {
       assert.ok(t1.called);
       assert.ok(t2.called);
@@ -877,6 +885,7 @@ describe('GatherRunner', function() {
       driver: fakeDriver,
       requestedUrl: 'https://example.com',
       settings: config.settings,
+      computedCache: new Map(),
     };
 
     return GatherRunner.run(config.passes, options)
@@ -904,7 +913,7 @@ describe('GatherRunner', function() {
         gatherers: [{instance: new TestGatherer()}],
       }],
     });
-    const options = {driver, requestedUrl, settings: config.settings};
+    const options = {driver, requestedUrl, settings: config.settings, computedCache: new Map()};
     const artifacts = await GatherRunner.run(config.passes, options);
 
     expect(artifacts.PageLoadError).toMatchObject({code: 'NO_DOCUMENT_REQUEST'});
@@ -951,7 +960,7 @@ describe('GatherRunner', function() {
       },
       online: true,
     });
-    const options = {driver, requestedUrl, settings: config.settings};
+    const options = {driver, requestedUrl, settings: config.settings, computedCache: new Map()};
     const artifacts = await GatherRunner.run(config.passes, options);
 
     // t1.pass() and t2.pass() called; t3.pass(), after the error, was not.
@@ -1444,6 +1453,7 @@ describe('GatherRunner', function() {
         driver: fakeDriver,
         requestedUrl: 'https://example.com',
         settings: config.settings,
+        computedCache: new Map(),
       });
 
       // Ensure artifacts returned and not errors.
@@ -1500,6 +1510,7 @@ describe('GatherRunner', function() {
         driver: fakeDriver,
         requestedUrl: 'https://example.com',
         settings: config.settings,
+        computedCache: new Map(),
       }).then(artifacts => {
         gathererNames.forEach(gathererName => {
           assert.strictEqual(artifacts[gathererName], gathererName);
@@ -1578,6 +1589,7 @@ describe('GatherRunner', function() {
         driver: fakeDriver,
         requestedUrl: 'https://example.com',
         settings: config.settings,
+        computedCache: new Map(),
       });
       assert.deepStrictEqual(artifacts.LighthouseRunWarnings, runWarnings);
     });
@@ -1633,6 +1645,7 @@ describe('GatherRunner', function() {
         driver: fakeDriver,
         requestedUrl: 'https://example.com',
         settings: config.settings,
+        computedCache: new Map(),
       }).then(artifacts => {
         gathererNames.forEach(gathererName => {
           const errorArtifact = artifacts[gathererName];
@@ -1657,6 +1670,7 @@ describe('GatherRunner', function() {
         driver: fakeDriver,
         requestedUrl: 'https://example.com',
         settings: config.settings,
+        computedCache: new Map(),
       }).then(_ => assert.ok(false), _ => assert.ok(true));
     });
 
@@ -1685,6 +1699,7 @@ describe('GatherRunner', function() {
         driver: unresolvedDriver,
         requestedUrl,
         settings: config.settings,
+        computedCache: new Map(),
       }).then(artifacts => {
         assert.equal(artifacts.LighthouseRunWarnings.length, 1);
         expect(artifacts.LighthouseRunWarnings[0])
@@ -1713,6 +1728,7 @@ describe('GatherRunner', function() {
         driver: timedoutDriver,
         requestedUrl,
         settings: config.settings,
+        computedCache: new Map(),
       }).then(artifacts => {
         assert.equal(artifacts.LighthouseRunWarnings.length, 1);
         expect(artifacts.LighthouseRunWarnings[0])
@@ -1745,6 +1761,7 @@ describe('GatherRunner', function() {
         driver: unresolvedDriver,
         requestedUrl,
         settings: config.settings,
+        computedCache: new Map(),
       })
         .then(_ => {
           assert.ok(true);

From 240782fe5df6d8a6bbca97c22853bc2da0655823 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Mon, 3 May 2021 18:05:13 -0400
Subject: [PATCH 07/17] go back

---
 lighthouse-core/fraggle-rock/gather/base-gatherer.js | 2 ++
 lighthouse-core/gather/gather-runner.js              | 1 -
 lighthouse-core/gather/gatherers/link-elements.js    | 4 ++--
 types/gatherer.d.ts                                  | 1 -
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lighthouse-core/fraggle-rock/gather/base-gatherer.js b/lighthouse-core/fraggle-rock/gather/base-gatherer.js
index 852ee4227648..32ce86e72cfb 100644
--- a/lighthouse-core/fraggle-rock/gather/base-gatherer.js
+++ b/lighthouse-core/fraggle-rock/gather/base-gatherer.js
@@ -90,6 +90,8 @@ class FRGatherer {
    * @return {Promise<LH.Gatherer.PhaseResultNonPromise>}
    */
   async afterPass(passContext, loadData) {
+    // @ts-ignore Default meta type does not include dependencies.
+    if (this.meta.dependencies) throw Error('Legacy gatherer should not have dependencies.');
     await this.stopSensitiveInstrumentation({...passContext, dependencies: {}});
     await this.stopInstrumentation({...passContext, dependencies: {}});
     return this.getArtifact({...passContext, dependencies: {}});
diff --git a/lighthouse-core/gather/gather-runner.js b/lighthouse-core/gather/gather-runner.js
index ea666b514390..73c53cae12ef 100644
--- a/lighthouse-core/gather/gather-runner.js
+++ b/lighthouse-core/gather/gather-runner.js
@@ -740,7 +740,6 @@ class GatherRunner {
           baseArtifacts,
           computedCache: options.computedCache,
           LighthouseRunWarnings: baseArtifacts.LighthouseRunWarnings,
-          dependencies: {},
         };
         const passResults = await GatherRunner.runPass(passContext);
         Object.assign(artifacts, passResults.artifacts);
diff --git a/lighthouse-core/gather/gatherers/link-elements.js b/lighthouse-core/gather/gatherers/link-elements.js
index b3110a6cca16..15dcbc1ad06e 100644
--- a/lighthouse-core/gather/gatherers/link-elements.js
+++ b/lighthouse-core/gather/gatherers/link-elements.js
@@ -156,12 +156,12 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.FRTransitionalContext} passContext
+   * @param {LH.Gatherer.PassContext} passContext
    * @param {LH.Gatherer.LoadData} loadData
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
   async afterPass(passContext, loadData) {
-    return await this._getArtifact(passContext, loadData.networkRecords);
+    return await this._getArtifact({...passContext, dependencies: {}}, loadData.networkRecords);
   }
 
   /**
diff --git a/types/gatherer.d.ts b/types/gatherer.d.ts
index ccb401347782..f6bc087f5f69 100644
--- a/types/gatherer.d.ts
+++ b/types/gatherer.d.ts
@@ -61,7 +61,6 @@ declare global {
       /** Gatherers can push to this array to add top-level warnings to the LHR. */
       LighthouseRunWarnings: Array<string | IcuMessage>;
       baseArtifacts: BaseArtifacts;
-      dependencies: {};
     }
 
     export interface LoadData {

From 664ba779f9dc23955362b83964fd1feefbf314f5 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Mon, 3 May 2021 18:27:21 -0400
Subject: [PATCH 08/17] runner test

---
 lighthouse-core/test/runner-test.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lighthouse-core/test/runner-test.js b/lighthouse-core/test/runner-test.js
index 49b8d30bfa2c..9fcf057c63ac 100644
--- a/lighthouse-core/test/runner-test.js
+++ b/lighthouse-core/test/runner-test.js
@@ -30,7 +30,7 @@ const i18n = require('../lib/i18n/i18n.js');
 describe('Runner', () => {
   const defaultGatherFn = opts => Runner._gatherArtifactsFromBrowser(
     opts.requestedUrl,
-    opts,
+    {...opts, computedCache: new Map()},
     null
   );
 
@@ -316,7 +316,7 @@ describe('Runner', () => {
       ],
     });
 
-    return Runner.run({}, {config}).then(results => {
+    return Runner.run({}, {config, computedCache: new Map()}).then(results => {
       const audits = results.lhr.audits;
       assert.equal(audits['user-timings'].displayValue, '2 user timings');
       assert.deepStrictEqual(audits['user-timings'].details.items.map(i => i.startTime),
@@ -555,7 +555,7 @@ describe('Runner', () => {
       ],
     });
 
-    return Runner.run({}, {config}).then(results => {
+    return Runner.run({}, {config, computedCache: new Map()}).then(results => {
       const audits = results.lhr.audits;
       assert.equal(audits['critical-request-chains'].displayValue, '5 chains found');
       assert.equal(audits['critical-request-chains'].details.longestChain.transferSize, 2468);

From bc43a9522917d333f31cdefe1f0a505f126c7798 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 4 May 2021 13:17:43 -0400
Subject: [PATCH 09/17] rn context

---
 .../gather/gatherers/link-elements.js         | 34 +++++++++----------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/lighthouse-core/gather/gatherers/link-elements.js b/lighthouse-core/gather/gatherers/link-elements.js
index 15dcbc1ad06e..e7cae9f040d8 100644
--- a/lighthouse-core/gather/gatherers/link-elements.js
+++ b/lighthouse-core/gather/gatherers/link-elements.js
@@ -89,13 +89,13 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.FRTransitionalContext} passContext
+   * @param {LH.Gatherer.FRTransitionalContext} context
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
-  static getLinkElementsInDOM(passContext) {
+  static getLinkElementsInDOM(context) {
     // We'll use evaluateAsync because the `node.getAttribute` method doesn't actually normalize
     // the values like access from JavaScript does.
-    return passContext.driver.executionContext.evaluate(getLinkElementsInDOM, {
+    return context.driver.executionContext.evaluate(getLinkElementsInDOM, {
       args: [],
       useIsolation: true,
       deps: [
@@ -106,12 +106,12 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.FRTransitionalContext} passContext
+   * @param {LH.Gatherer.FRTransitionalContext} context
    * @param {LH.Artifacts.NetworkRequest[]} networkRecords
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
-  static async getLinkElementsInHeaders(passContext, networkRecords) {
-    const finalUrl = passContext.url;
+  static async getLinkElementsInHeaders(context, networkRecords) {
+    const finalUrl = context.url;
     const mainDocument = NetworkAnalyzer.findMainDocument(networkRecords, finalUrl);
 
     /** @type {LH.Artifacts['LinkElements']} */
@@ -138,13 +138,13 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.FRTransitionalContext} passContext
+   * @param {LH.Gatherer.FRTransitionalContext} context
    * @param {LH.Artifacts.NetworkRequest[]} networkRecords
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
-  async _getArtifact(passContext, networkRecords) {
-    const fromDOM = await LinkElements.getLinkElementsInDOM(passContext);
-    const fromHeaders = await LinkElements.getLinkElementsInHeaders(passContext, networkRecords);
+  async _getArtifact(context, networkRecords) {
+    const fromDOM = await LinkElements.getLinkElementsInDOM(context);
+    const fromHeaders = await LinkElements.getLinkElementsInHeaders(context, networkRecords);
     const linkElements = fromDOM.concat(fromHeaders);
 
     for (const link of linkElements) {
@@ -156,21 +156,21 @@ class LinkElements extends FRGatherer {
   }
 
   /**
-   * @param {LH.Gatherer.PassContext} passContext
+   * @param {LH.Gatherer.PassContext} context
    * @param {LH.Gatherer.LoadData} loadData
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
-  async afterPass(passContext, loadData) {
-    return await this._getArtifact({...passContext, dependencies: {}}, loadData.networkRecords);
+  async afterPass(context, loadData) {
+    return await this._getArtifact({...context, dependencies: {}}, loadData.networkRecords);
   }
 
   /**
-   * @param {LH.Gatherer.FRTransitionalContext<'DevtoolsLog'>} passContext
+   * @param {LH.Gatherer.FRTransitionalContext<'DevtoolsLog'>} context
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
-  async getArtifact(passContext) {
-    const records = await NetworkRecords.request(passContext.dependencies.DevtoolsLog, passContext);
-    return await this._getArtifact(passContext, records);
+  async getArtifact(context) {
+    const records = await NetworkRecords.request(context.dependencies.DevtoolsLog, context);
+    return await this._getArtifact(context, records);
   }
 }
 

From be85784c5e5177536a82554e8392f1eebe16a30f Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 4 May 2021 13:24:43 -0400
Subject: [PATCH 10/17] rm async

---
 lighthouse-core/gather/gatherers/link-elements.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lighthouse-core/gather/gatherers/link-elements.js b/lighthouse-core/gather/gatherers/link-elements.js
index e7cae9f040d8..e0ac7fcea950 100644
--- a/lighthouse-core/gather/gatherers/link-elements.js
+++ b/lighthouse-core/gather/gatherers/link-elements.js
@@ -108,9 +108,9 @@ class LinkElements extends FRGatherer {
   /**
    * @param {LH.Gatherer.FRTransitionalContext} context
    * @param {LH.Artifacts.NetworkRequest[]} networkRecords
-   * @return {Promise<LH.Artifacts['LinkElements']>}
+   * @return {LH.Artifacts['LinkElements']}
    */
-  static async getLinkElementsInHeaders(context, networkRecords) {
+  static getLinkElementsInHeaders(context, networkRecords) {
     const finalUrl = context.url;
     const mainDocument = NetworkAnalyzer.findMainDocument(networkRecords, finalUrl);
 
@@ -144,7 +144,7 @@ class LinkElements extends FRGatherer {
    */
   async _getArtifact(context, networkRecords) {
     const fromDOM = await LinkElements.getLinkElementsInDOM(context);
-    const fromHeaders = await LinkElements.getLinkElementsInHeaders(context, networkRecords);
+    const fromHeaders = LinkElements.getLinkElementsInHeaders(context, networkRecords);
     const linkElements = fromDOM.concat(fromHeaders);
 
     for (const link of linkElements) {

From b384121ebeb1d182a07728bc69fe591006406621 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 4 May 2021 13:33:42 -0400
Subject: [PATCH 11/17] fix

---
 lighthouse-core/gather/gatherers/link-elements.js | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/lighthouse-core/gather/gatherers/link-elements.js b/lighthouse-core/gather/gatherers/link-elements.js
index e0ac7fcea950..dbb30c8ff48f 100644
--- a/lighthouse-core/gather/gatherers/link-elements.js
+++ b/lighthouse-core/gather/gatherers/link-elements.js
@@ -82,10 +82,13 @@ function getLinkElementsInDOM() {
 /* c8 ignore stop */
 
 class LinkElements extends FRGatherer {
-  /** @type {LH.Gatherer.GathererMeta<'DevtoolsLog'>} */
-  meta = {
-    supportedModes: ['timespan', 'navigation'],
-    dependencies: {DevtoolsLog: DevtoolsLog.symbol},
+  constructor() {
+    super();
+    /** @type {LH.Gatherer.GathererMeta<'DevtoolsLog'>} */
+    this.meta = {
+      supportedModes: ['timespan', 'navigation'],
+      dependencies: {DevtoolsLog: DevtoolsLog.symbol},
+    };
   }
 
   /**

From 94595270c3a0f298706094b97368d9f869c711f1 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 4 May 2021 13:53:29 -0400
Subject: [PATCH 12/17] update dt

---
 .../lighthouse/lighthouse-successful-run-expected.txt         | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/third-party/chromium-webtests/webtests/http/tests/devtools/lighthouse/lighthouse-successful-run-expected.txt b/third-party/chromium-webtests/webtests/http/tests/devtools/lighthouse/lighthouse-successful-run-expected.txt
index ad9396418743..d14e079d6599 100644
--- a/third-party/chromium-webtests/webtests/http/tests/devtools/lighthouse/lighthouse-successful-run-expected.txt
+++ b/third-party/chromium-webtests/webtests/http/tests/devtools/lighthouse/lighthouse-successful-run-expected.txt
@@ -89,6 +89,7 @@ Gathering in-page: SourceMaps
 Gathering in-page: FullPageScreenshot
 Gathering trace
 Gathering devtoolsLog & network records
+Computing artifact: NetworkRecords
 Running afterPass methods
 Gathering: CSSUsage
 Gathering: JsUsage
@@ -132,6 +133,7 @@ Loading page & waiting for onload
 Running pass methods
 Gathering in-page: ServiceWorker
 Gathering devtoolsLog & network records
+Computing artifact: NetworkRecords
 Running afterPass methods
 Gathering: ServiceWorker
 Running redirectPass pass
@@ -144,12 +146,12 @@ Loading page & waiting for onload
 Running pass methods
 Gathering in-page: HTTPRedirect
 Gathering devtoolsLog & network records
+Computing artifact: NetworkRecords
 Running afterPass methods
 Gathering: HTTPRedirect
 Disconnecting from browser...
 Analyzing and running audits...
 Auditing: Uses HTTPS
-Computing artifact: NetworkRecords
 Auditing: Redirects HTTP traffic to HTTPS
 Auditing: Registers a service worker that controls page and `start_url`
 Auditing: Has a `<meta name="viewport">` tag with `width` or `initial-scale`

From 36ebf93907cfa240d76714cdd8df4cffecb28af9 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 4 May 2021 14:00:19 -0400
Subject: [PATCH 13/17] rephrase error

---
 lighthouse-core/fraggle-rock/gather/base-gatherer.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lighthouse-core/fraggle-rock/gather/base-gatherer.js b/lighthouse-core/fraggle-rock/gather/base-gatherer.js
index 32ce86e72cfb..901192beb9f9 100644
--- a/lighthouse-core/fraggle-rock/gather/base-gatherer.js
+++ b/lighthouse-core/fraggle-rock/gather/base-gatherer.js
@@ -90,8 +90,9 @@ class FRGatherer {
    * @return {Promise<LH.Gatherer.PhaseResultNonPromise>}
    */
   async afterPass(passContext, loadData) {
-    // @ts-ignore Default meta type does not include dependencies.
-    if (this.meta.dependencies) throw Error('Legacy gatherer should not have dependencies.');
+    if ('dependencies' in this.meta) {
+      throw Error('Gatherer with dependencies should override afterPass');
+    }
     await this.stopSensitiveInstrumentation({...passContext, dependencies: {}});
     await this.stopInstrumentation({...passContext, dependencies: {}});
     return this.getArtifact({...passContext, dependencies: {}});

From 87ba41f8f8c945cbdb25818d7f9c12f9d7e9a2ae Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 4 May 2021 15:04:14 -0400
Subject: [PATCH 14/17] test cases

---
 .../fraggle-rock/gather/base-gatherer-test.js | 15 +++++++
 .../gather/gatherers/link-elements-test.js    | 40 +++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/lighthouse-core/test/fraggle-rock/gather/base-gatherer-test.js b/lighthouse-core/test/fraggle-rock/gather/base-gatherer-test.js
index 8ea364bb74ab..9462ad5dbb6c 100644
--- a/lighthouse-core/test/fraggle-rock/gather/base-gatherer-test.js
+++ b/lighthouse-core/test/fraggle-rock/gather/base-gatherer-test.js
@@ -68,5 +68,20 @@ describe('BaseGatherer', () => {
       expect(gatherer.stopInstrumentation).toHaveBeenCalled();
       expect(gatherer.stopSensitiveInstrumentation).toHaveBeenCalled();
     });
+
+    it('throws if no override and has dependencies', async () => {
+      class MyGatherer extends Gatherer {
+        /** @type {LH.Gatherer.GathererMeta<'Trace'>} */
+        meta = {supportedModes: ['timespan'], dependencies: {Trace: Symbol('Trace')}};
+        stopInstrumentation = jest.fn();
+        stopSensitiveInstrumentation = jest.fn();
+      }
+
+      const gatherer = new MyGatherer();
+      const afterPassPromise = gatherer.afterPass(fakeParam, fakeParam);
+      await expect(afterPassPromise).rejects.toThrowError(/Gatherer with dependencies/);
+      expect(gatherer.stopInstrumentation).not.toHaveBeenCalled();
+      expect(gatherer.stopSensitiveInstrumentation).not.toHaveBeenCalled();
+    });
   });
 });
diff --git a/lighthouse-core/test/gather/gatherers/link-elements-test.js b/lighthouse-core/test/gather/gatherers/link-elements-test.js
index 8dce0f4d0f37..1c5354dca6bb 100644
--- a/lighthouse-core/test/gather/gatherers/link-elements-test.js
+++ b/lighthouse-core/test/gather/gatherers/link-elements-test.js
@@ -8,6 +8,9 @@
 /* eslint-env jest */
 
 const LinkElements = require('../../../gather/gatherers/link-elements.js');
+const NetworkRecords = require('../../../computed/network-records.js');
+
+jest.mock('../../../computed/network-records.js');
 
 describe('Link Elements gatherer', () => {
   /**
@@ -91,3 +94,40 @@ describe('Link Elements gatherer', () => {
     ]);
   });
 });
+
+describe('FR compat', () => {
+  /** @type {LinkElements} */
+  let gatherer;
+  /** @type {any[]} */
+  let networkRecords;
+  /** @type {any[]} */
+  let devtoolsLog;
+
+  beforeEach(() => {
+    networkRecords = ['1', '2'];
+    devtoolsLog = ['3', '4'];
+    gatherer = new LinkElements();
+    gatherer._getArtifact = jest.fn();
+    NetworkRecords.request = jest.fn().mockReturnValue(Promise.resolve(networkRecords));
+  });
+
+  it('uses loadData in legacy mode', async () => {
+    const context = {
+      computedCache: new Map(),
+      dependencies: {},
+    };
+    await gatherer.afterPass(context, {networkRecords, devtoolsLog});
+    expect(gatherer._getArtifact).toHaveBeenCalledWith(context, networkRecords);
+    expect(NetworkRecords.request).not.toHaveBeenCalled();
+  });
+
+  it('uses dependency in FR', async () => {
+    const context = {
+      computedCache: new Map(),
+      dependencies: {DevtoolsLog: devtoolsLog},
+    };
+    await gatherer.getArtifact(context);
+    expect(gatherer._getArtifact).toHaveBeenCalledWith(context, networkRecords);
+    expect(NetworkRecords.request).toHaveBeenCalledWith(devtoolsLog, context);
+  });
+});

From b5ab80572322590729c07b81d95e224a293e7773 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 4 May 2021 15:06:20 -0400
Subject: [PATCH 15/17] comments

---
 lighthouse-core/gather/gatherers/link-elements.js | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/lighthouse-core/gather/gatherers/link-elements.js b/lighthouse-core/gather/gatherers/link-elements.js
index dbb30c8ff48f..a2561adaefcd 100644
--- a/lighthouse-core/gather/gatherers/link-elements.js
+++ b/lighthouse-core/gather/gatherers/link-elements.js
@@ -84,7 +84,11 @@ function getLinkElementsInDOM() {
 class LinkElements extends FRGatherer {
   constructor() {
     super();
-    /** @type {LH.Gatherer.GathererMeta<'DevtoolsLog'>} */
+    /**
+     * This needs to be in the constructor.
+     * https://github.com/GoogleChrome/lighthouse/issues/12134
+     * @type {LH.Gatherer.GathererMeta<'DevtoolsLog'>}
+     */
     this.meta = {
       supportedModes: ['timespan', 'navigation'],
       dependencies: {DevtoolsLog: DevtoolsLog.symbol},
@@ -164,7 +168,7 @@ class LinkElements extends FRGatherer {
    * @return {Promise<LH.Artifacts['LinkElements']>}
    */
   async afterPass(context, loadData) {
-    return await this._getArtifact({...context, dependencies: {}}, loadData.networkRecords);
+    return this._getArtifact({...context, dependencies: {}}, loadData.networkRecords);
   }
 
   /**
@@ -173,7 +177,7 @@ class LinkElements extends FRGatherer {
    */
   async getArtifact(context) {
     const records = await NetworkRecords.request(context.dependencies.DevtoolsLog, context);
-    return await this._getArtifact(context, records);
+    return this._getArtifact(context, records);
   }
 }
 

From 0feb8f109ad5e026f05ad68aff48cd99ec4be67e Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 4 May 2021 15:12:25 -0400
Subject: [PATCH 16/17] add to fr config

---
 lighthouse-core/fraggle-rock/config/default-config.js | 3 +++
 lighthouse-core/test/fraggle-rock/api-test-pptr.js    | 4 ++--
 types/artifacts.d.ts                                  | 1 -
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/lighthouse-core/fraggle-rock/config/default-config.js b/lighthouse-core/fraggle-rock/config/default-config.js
index 519b4f7d8c66..0e25922e7ae5 100644
--- a/lighthouse-core/fraggle-rock/config/default-config.js
+++ b/lighthouse-core/fraggle-rock/config/default-config.js
@@ -24,6 +24,7 @@ const artifacts = {
   GlobalListeners: '',
   IFrameElements: '',
   InstallabilityErrors: '',
+  LinkElements: '',
   MetaElements: '',
   NetworkUserAgent: '',
   PasswordInputsWithPreventedPaste: '',
@@ -60,6 +61,7 @@ const defaultConfig = {
     {id: artifacts.GlobalListeners, gatherer: 'global-listeners'},
     {id: artifacts.IFrameElements, gatherer: 'iframe-elements'},
     {id: artifacts.InstallabilityErrors, gatherer: 'installability-errors'},
+    {id: artifacts.LinkElements, gatherer: 'link-elements'},
     {id: artifacts.MetaElements, gatherer: 'meta-elements'},
     {id: artifacts.NetworkUserAgent, gatherer: 'network-user-agent'},
     {id: artifacts.PasswordInputsWithPreventedPaste, gatherer: 'dobetterweb/password-inputs-with-prevented-paste'},
@@ -94,6 +96,7 @@ const defaultConfig = {
         artifacts.GlobalListeners,
         artifacts.IFrameElements,
         artifacts.InstallabilityErrors,
+        artifacts.LinkElements,
         artifacts.MetaElements,
         artifacts.NetworkUserAgent,
         artifacts.PasswordInputsWithPreventedPaste,
diff --git a/lighthouse-core/test/fraggle-rock/api-test-pptr.js b/lighthouse-core/test/fraggle-rock/api-test-pptr.js
index 0a74df8518ce..22e5a65bddac 100644
--- a/lighthouse-core/test/fraggle-rock/api-test-pptr.js
+++ b/lighthouse-core/test/fraggle-rock/api-test-pptr.js
@@ -121,7 +121,7 @@ describe('Fraggle Rock API', () => {
 
       const {auditResults, erroredAudits, failedAudits} = getAuditsBreakdown(lhr);
       // TODO(FR-COMPAT): This assertion can be removed when full compatibility is reached.
-      expect(auditResults.length).toMatchInlineSnapshot(`24`);
+      expect(auditResults.length).toMatchInlineSnapshot(`25`);
 
       expect(erroredAudits).toHaveLength(0);
       expect(failedAudits.map(audit => audit.id)).toContain('errors-in-console');
@@ -159,7 +159,7 @@ describe('Fraggle Rock API', () => {
       const {lhr} = result;
       const {auditResults, failedAudits, erroredAudits} = getAuditsBreakdown(lhr);
       // TODO(FR-COMPAT): This assertion can be removed when full compatibility is reached.
-      expect(auditResults.length).toMatchInlineSnapshot(`102`);
+      expect(auditResults.length).toMatchInlineSnapshot(`103`);
       expect(erroredAudits).toHaveLength(0);
 
       const failedAuditIds = failedAudits.map(audit => audit.id);
diff --git a/types/artifacts.d.ts b/types/artifacts.d.ts
index 8275fd809708..0b67cb9b9e67 100644
--- a/types/artifacts.d.ts
+++ b/types/artifacts.d.ts
@@ -28,7 +28,6 @@ declare global {
       | 'ImageElements'
       | 'InspectorIssues'
       | 'JsUsage'
-      | 'LinkElements'
       | 'MainDocumentContent'
       | 'Manifest'
       | 'MixedContent'

From 5e4c5aab0a01afdde997aa97fe4b419b8ef1c5c9 Mon Sep 17 00:00:00 2001
From: Adam Raine <ad.st.raine@gmail.com>
Date: Tue, 11 May 2021 14:36:43 -0400
Subject: [PATCH 17/17] type

---
 lighthouse-core/test/gather/gatherers/css-usage-test.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lighthouse-core/test/gather/gatherers/css-usage-test.js b/lighthouse-core/test/gather/gatherers/css-usage-test.js
index b52c60dc7794..bc2a4f40eb6e 100644
--- a/lighthouse-core/test/gather/gatherers/css-usage-test.js
+++ b/lighthouse-core/test/gather/gatherers/css-usage-test.js
@@ -36,6 +36,7 @@ describe('.getArtifact', () => {
       driver: driver.asDriver(),
       url: 'https://example.com',
       gatherMode: 'snapshot',
+      computedCache: new Map(),
       dependencies: {},
     };
     const gatherer = new CSSUsage();
@@ -89,6 +90,7 @@ describe('.getArtifact', () => {
       driver: driver.asDriver(),
       url: 'https://example.com',
       gatherMode: 'snapshot',
+      computedCache: new Map(),
       dependencies: {},
     };
     const gatherer = new CSSUsage();