From 020333031f66684c4c153d080fc42b29c384f732 Mon Sep 17 00:00:00 2001
From: Brendan Kenny <bckenny@gmail.com>
Date: Mon, 20 Aug 2018 11:53:25 -0700
Subject: [PATCH] core(tsc): add explicit index signature in
 mainthread-work-breakdown (#5859)

---
 .../audits/mainthread-work-breakdown.js       |  7 ++++--
 lighthouse-core/lib/task-groups.js            | 22 ++++++++++---------
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/lighthouse-core/audits/mainthread-work-breakdown.js b/lighthouse-core/audits/mainthread-work-breakdown.js
index c5f6b1c07a20..4ec93e078088 100644
--- a/lighthouse-core/audits/mainthread-work-breakdown.js
+++ b/lighthouse-core/audits/mainthread-work-breakdown.js
@@ -28,6 +28,8 @@ const UIStrings = {
 
 const str_ = i18n.createMessageInstanceIdFn(__filename, UIStrings);
 
+/** @typedef {import('../lib/task-groups.js').TaskGroupIds} TaskGroupIds */
+
 class MainThreadWorkBreakdown extends Audit {
   /**
    * @return {LH.Audit.Meta}
@@ -56,10 +58,10 @@ class MainThreadWorkBreakdown extends Audit {
 
   /**
    * @param {LH.Artifacts.TaskNode[]} tasks
-   * @return {Map<string, number>}
+   * @return {Map<TaskGroupIds, number>}
    */
   static getExecutionTimingsByGroup(tasks) {
-    /** @type {Map<string, number>} */
+    /** @type {Map<TaskGroupIds, number>} */
     const result = new Map();
 
     for (const task of tasks) {
@@ -86,6 +88,7 @@ class MainThreadWorkBreakdown extends Audit {
     const executionTimings = MainThreadWorkBreakdown.getExecutionTimingsByGroup(tasks);
 
     let totalExecutionTime = 0;
+    /** @type {Record<string, number>} */
     const categoryTotals = {};
     const results = Array.from(executionTimings).map(([groupId, rawDuration]) => {
       const duration = rawDuration * multiplier;
diff --git a/lighthouse-core/lib/task-groups.js b/lighthouse-core/lib/task-groups.js
index d61af424d655..07d03fd0ad2e 100644
--- a/lighthouse-core/lib/task-groups.js
+++ b/lighthouse-core/lib/task-groups.js
@@ -5,9 +5,11 @@
  */
 'use strict';
 
+/** @typedef {'parseHTML'|'styleLayout'|'paintCompositeRender'|'scriptParseCompile'|'scriptEvaluation'|'garbageCollection'|'other'} TaskGroupIds */
+
 /**
  * @typedef TaskGroup
- * @property {string} id
+ * @property {TaskGroupIds} id
  * @property {string} label
  * @property {string[]} traceEventNames
  */
@@ -16,15 +18,16 @@
  * Make sure the traceEventNames keep up with the ones in DevTools
  * @see https://cs.chromium.org/chromium/src/third_party/blink/renderer/devtools/front_end/timeline_model/TimelineModel.js?type=cs&q=TimelineModel.TimelineModel.RecordType+%3D&g=0&l=1156
  * @see https://cs.chromium.org/chromium/src/third_party/blink/renderer/devtools/front_end/timeline/TimelineUIUtils.js?type=cs&q=_initEventStyles+-f:out+f:devtools&sq=package:chromium&g=0&l=39
+ * @type {{[P in TaskGroupIds]: {id: P, label: string, traceEventNames: Array<string>}}}
  */
 const taskGroups = {
   parseHTML: {
-    id: '',
+    id: 'parseHTML',
     label: 'Parse HTML & CSS',
     traceEventNames: ['ParseHTML', 'ParseAuthorStyleSheet'],
   },
   styleLayout: {
-    id: '',
+    id: 'styleLayout',
     label: 'Style & Layout',
     traceEventNames: [
       'ScheduleStyleRecalculation',
@@ -35,7 +38,7 @@ const taskGroups = {
     ],
   },
   paintCompositeRender: {
-    id: '',
+    id: 'paintCompositeRender',
     label: 'Rendering',
     traceEventNames: [
       'Animation',
@@ -55,12 +58,12 @@ const taskGroups = {
     ],
   },
   scriptParseCompile: {
-    id: '',
+    id: 'scriptParseCompile',
     label: 'Script Parsing & Compilation',
     traceEventNames: ['v8.compile', 'v8.compileModule', 'v8.parseOnBackground'],
   },
   scriptEvaluation: {
-    id: '',
+    id: 'scriptEvaluation',
     label: 'Script Evaluation',
     traceEventNames: [
       'EventDispatch',
@@ -75,7 +78,7 @@ const taskGroups = {
     ],
   },
   garbageCollection: {
-    id: '',
+    id: 'garbageCollection',
     label: 'Garbage Collection',
     traceEventNames: [
       'GCEvent',
@@ -87,7 +90,7 @@ const taskGroups = {
     ],
   },
   other: {
-    id: '',
+    id: 'other',
     label: 'Other',
     traceEventNames: [
       'MessageLoop::RunTask',
@@ -99,8 +102,7 @@ const taskGroups = {
 
 /** @type {Object<string, TaskGroup>} */
 const taskNameToGroup = {};
-for (const [groupId, group] of Object.entries(taskGroups)) {
-  group.id = groupId;
+for (const group of Object.values(taskGroups)) {
   for (const traceEventName of group.traceEventNames) {
     taskNameToGroup[traceEventName] = group;
   }