take only the subset of type event emitting we need

lighthouse-core/gather/connections/connection.js

@@ -9,8 +9,10 @@ const EventEmitter = require('events').EventEmitter;
 const log = require('lighthouse-logger');
 const LHError = require('../../lib/errors');
 
+// TODO(bckenny): CommandCallback properties should be tied by command type
 /**
- * @typedef {LH.StrictEventEmitter<{'protocolevent': [LH.Protocol.RawEventMessage]}>} CrdpEventMessageEmitter
+ * @typedef {{'protocolevent': [LH.Protocol.RawEventMessage]}} ProtocolEventRecord
+ * @typedef {LH.Protocol.StrictEventEmitter<ProtocolEventRecord>} CrdpEventMessageEmitter
  * @typedef {LH.CrdpCommands[keyof LH.CrdpCommands]} CommandInfo
  * @typedef {{resolve: function(Promise<CommandInfo['returnType']>): void, method: keyof LH.CrdpCommands}} CommandCallback
  */

lighthouse-core/gather/driver.js

@@ -32,7 +32,7 @@ const DEFAULT_NETWORK_QUIET_THRESHOLD = 5000;
 const DEFAULT_CPU_QUIET_THRESHOLD = 0;
 
 /**
- * @typedef {LH.StrictEventEmitter<LH.CrdpEvents>} CrdpEventEmitter
+ * @typedef {LH.Protocol.StrictEventEmitter<LH.CrdpEvents>} CrdpEventEmitter
  */
 
 class Driver {

typings/externs.d.ts

@@ -6,7 +6,6 @@
 
 import _Crdp from 'devtools-protocol/types/protocol';
 import _CrdpMappings from 'devtools-protocol/types/protocol-mapping'
-import _StrictEventEmitter from '../third-party/strict-event-emitter-types/index';
 import { EventEmitter } from 'events';
 
 declare global {
@@ -41,6 +40,9 @@ declare global {
       T[P];
   };
 
+  /** Filter to convince the compiler that T is spreadable. */
+  type IsTuple<T> = T extends any[] ? T : never;
+
   /**
    * Exclude void from T
    */
@@ -58,8 +60,6 @@ declare global {
     export import Crdp = _Crdp;
     export import CrdpEvents = _CrdpMappings.Events;
     export import CrdpCommands = _CrdpMappings.Commands;
-    export type StrictEventEmitter<TEventRecord, TEmitterType = EventEmitter, TEmitRecord = TEventRecord> =
-      _StrictEventEmitter<TEmitterType, TEventRecord, TEmitRecord>;
 
     interface ThrottlingSettings {
       // simulation settings

typings/protocol.d.ts

@@ -29,6 +29,27 @@ declare global {
      * responses.
      */
     export type RawMessage = RawCommandMessage | RawEventMessage;
+
+    /**
+     * A more strictly-typed EventEmitter interface that checks the association
+     * of event name and listener payload. TEventRecord should be a record mapping
+     * event names to tuples that can contain zero or more items, which will
+     * serve as the arguments to event listener callbacks.
+     * Inspired by work from https://github.com/bterlson/strict-event-emitter-types.
+     */
+    export type StrictEventEmitter<TEventRecord> = {
+      on<E extends keyof TEventRecord>(event: E, listener: (...args: IsTuple<TEventRecord[E]>) => void): void;
+
+      addListener<E extends keyof TEventRecord>(event: E, listener: (...args: IsTuple<TEventRecord[E]>) => void): void;
+
+      removeListener<E extends keyof TEventRecord>(event: E, listener: Function): void;
+
+      removeAllListeners<E extends keyof TEventRecord>(event?: E): void;
+
+      once<E extends keyof TEventRecord>(event: E, listener: (...args: IsTuple<TEventRecord[E]>) => void): void;
+
+      emit<E extends keyof TEventRecord>(event: E, ...request: IsTuple<TEventRecord[E]>): void;
+    }
   }
 }