diff --git a/packages/service-worker/worker/src/adapter.ts b/packages/service-worker/worker/src/adapter.ts
index ad56aee12a..1bee5c20a4 100644
--- a/packages/service-worker/worker/src/adapter.ts
+++ b/packages/service-worker/worker/src/adapter.ts
@@ -18,7 +18,7 @@ import {NamedCacheStorage} from './named-cache-storage';
  */
 export class Adapter<T extends CacheStorage = CacheStorage> {
   readonly caches: NamedCacheStorage<T>;
-  private readonly origin: string;
+  readonly origin: string;
 
   constructor(protected readonly scopeUrl: string, caches: T) {
     const parsedScopeUrl = this.parseUrl(this.scopeUrl);
diff --git a/packages/service-worker/worker/src/service-worker.d.ts b/packages/service-worker/worker/src/service-worker.d.ts
index 976a4a70f0..69171abe3d 100644
--- a/packages/service-worker/worker/src/service-worker.d.ts
+++ b/packages/service-worker/worker/src/service-worker.d.ts
@@ -106,23 +106,54 @@ interface ExtendableMessageEvent extends ExtendableEvent {
   readonly source: Client|ServiceWorker|MessagePort|null;
 }
 
+// WorkerGlobalScope
+
+// Explicitly omit the `caches` property to disallow accessing `CacheStorage` APIs directly. All
+// interactions with `CacheStorage` should go through a `NamedCacheStorage` instance (exposed by the
+// `Adapter`).
+interface WorkerGlobalScope extends EventTarget, Omit<WindowOrWorkerGlobalScope, 'caches'> {
+  readonly location: WorkerLocation;
+  readonly navigator: WorkerNavigator;
+  readonly self: WorkerGlobalScope & typeof globalThis;
+
+  importScripts(...urls: string[]): void;
+  addEventListener<K extends keyof WorkerGlobalScopeEventMap>(type: K, listener: (this: WorkerGlobalScope, ev: WorkerGlobalScopeEventMap[K]) => any, options?: boolean | AddEventListenerOptions): void;
+  addEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;
+  removeEventListener<K extends keyof WorkerGlobalScopeEventMap>(type: K, listener: (this: WorkerGlobalScope, ev: WorkerGlobalScopeEventMap[K]) => any, options?: boolean | EventListenerOptions): void;
+  removeEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | EventListenerOptions): void;
+}
+
+interface WorkerGlobalScopeEventMap {
+  error: ErrorEvent;
+  languagechange: Event;
+  offline: Event;
+  online: Event;
+  rejectionhandled: PromiseRejectionEvent;
+  unhandledrejection: PromiseRejectionEvent;
+}
+
 // ServiceWorkerGlobalScope
 
-interface ServiceWorkerGlobalScope {
-  // Intentionally does not include a `caches` property to disallow accessing `CacheStorage` APIs
-  // directly. All interactions with `CacheStorage` should go through a `NamedCacheStorage` instance
-  // (exposed by the `Adapter`).
-  clients: Clients;
-  registration: ServiceWorkerRegistration;
+interface ServiceWorkerGlobalScope extends WorkerGlobalScope {
+  readonly clients: Clients;
+  readonly registration: ServiceWorkerRegistration;
+  readonly serviceWorker: ServiceWorker;
 
-  addEventListener(event: 'activate', fn: (event?: ExtendableEvent) => any): void;
-  addEventListener(event: 'message', fn: (event?: ExtendableMessageEvent) => any): void;
-  addEventListener(event: 'fetch', fn: (event?: FetchEvent) => any): void;
-  addEventListener(event: 'install', fn: (event?: ExtendableEvent) => any): void;
-  addEventListener(event: 'push', fn: (event?: PushEvent) => any): void;
-  addEventListener(event: 'notificationclick', fn: (event?: NotificationEvent) => any): void;
-  addEventListener(event: 'sync', fn: (event?: SyncEvent) => any): void;
-
-  fetch(request: Request|string): Promise<Response>;
   skipWaiting(): Promise<void>;
+  addEventListener<K extends keyof ServiceWorkerGlobalScopeEventMap>(type: K, listener: (this: ServiceWorkerGlobalScope, ev: ServiceWorkerGlobalScopeEventMap[K]) => any, options?: boolean | AddEventListenerOptions): void;
+  addEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;
+  removeEventListener<K extends keyof ServiceWorkerGlobalScopeEventMap>(type: K, listener: (this: ServiceWorkerGlobalScope, ev: ServiceWorkerGlobalScopeEventMap[K]) => any, options?: boolean | EventListenerOptions): void;
+  removeEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | EventListenerOptions): void;
+}
+
+interface ServiceWorkerGlobalScopeEventMap extends WorkerGlobalScopeEventMap {
+  activate: ExtendableEvent;
+  fetch: FetchEvent;
+  install: ExtendableEvent;
+  message: ExtendableMessageEvent;
+  messageerror: MessageEvent;
+  notificationclick: NotificationEvent;
+  notificationclose: NotificationEvent;
+  push: PushEvent;
+  sync: SyncEvent;
 }
diff --git a/packages/service-worker/worker/testing/scope.ts b/packages/service-worker/worker/testing/scope.ts
index 5acf62e354..f635e69034 100644
--- a/packages/service-worker/worker/testing/scope.ts
+++ b/packages/service-worker/worker/testing/scope.ts
@@ -37,13 +37,16 @@ export class SwTestHarnessBuilder {
   }
 
   build(): SwTestHarness {
-    return new SwTestHarness(this.server, this.caches, this.scopeUrl);
+    return new SwTestHarnessImpl(this.server, this.caches, this.scopeUrl) as SwTestHarness;
   }
 }
 
-export class SwTestHarness extends Adapter<MockCacheStorage> implements ServiceWorkerGlobalScope {
+export type SwTestHarness = SwTestHarnessImpl&ServiceWorkerGlobalScope;
+
+export class SwTestHarnessImpl extends Adapter<MockCacheStorage> implements
+    Partial<ServiceWorkerGlobalScope> {
   readonly clients = new MockClients();
-  private eventHandlers = new Map<string, Function>();
+  private eventHandlers = new Map<string, EventListener>();
   private skippedWaiting = false;
 
   private selfMessageQueue: any[] = [];
@@ -131,12 +134,26 @@ export class SwTestHarness extends Adapter<MockCacheStorage> implements ServiceW
     }
   }
 
-  addEventListener(event: string, handler: Function): void {
-    this.eventHandlers.set(event, handler);
+  addEventListener(
+      type: string, listener: EventListenerOrEventListenerObject,
+      options?: boolean|AddEventListenerOptions): void {
+    if (options !== undefined) {
+      throw new Error('Mock `addEventListener()` does not support `options`.');
+    }
+
+    const handler: EventListener =
+        (typeof listener === 'function') ? listener : evt => listener.handleEvent(evt);
+    this.eventHandlers.set(type, handler);
   }
 
-  removeEventListener(event: string, handler?: Function): void {
-    this.eventHandlers.delete(event);
+  removeEventListener(
+      type: string, listener: EventListenerOrEventListenerObject,
+      options?: boolean|AddEventListenerOptions): void {
+    if (options !== undefined) {
+      throw new Error('Mock `removeEventListener()` does not support `options`.');
+    }
+
+    this.eventHandlers.delete(type);
   }
 
   newRequest(url: string, init: Object = {}): Request {