refactor(aio): reorganize search service for easier testing

aio/src/app/app.component.ts

@@ -101,6 +101,9 @@ export class AppComponent implements OnInit {
   }
 
   ngOnInit() {
+    this.searchService.initWorker('app/search/search-worker.js');
+    this.searchService.loadIndex();
+
     this.onResize(window.innerWidth);
   }
 

aio/src/app/search/search.service.spec.ts

@@ -0,0 +1,24 @@
+import { ReflectiveInjector, NgZone } from '@angular/core';
+import { SearchService } from './search.service';
+
+xdescribe('SearchService', () => {
+
+  let injector: ReflectiveInjector;
+
+  beforeEach(() => {
+    injector = ReflectiveInjector.resolveAndCreate([
+        SearchService,
+        { provide: NgZone, useFactory: () => new NgZone({ enableLongStackTrace: false }) }
+    ]);
+  });
+
+  describe('loadIndex', () => {
+    it('should send a "load-index" message to the worker', () => {});
+    it('should connect the `ready` property to the response to the "load-index" message', () => {});
+  });
+
+  describe('search', () => {
+    it('should send a "query-index" message to the worker', () => {});
+    it('should push the response to the `searchResults` observable', () => {});
+  });
+});

aio/src/app/search/search.service.ts

@@ -4,7 +4,7 @@ Use of this source code is governed by an MIT-style license that
 can be found in the LICENSE file at http://angular.io/license
 */
 
-import { NgZone, Injectable } from '@angular/core';
+import { NgZone, Injectable, Type } from '@angular/core';
 import { Observable } from 'rxjs/Observable';
 import { Subject } from 'rxjs/Subject';
 import 'rxjs/add/operator/publishLast';
@@ -16,7 +16,6 @@ export interface QueryResults {
   results: Object[];
 }
 
-const SEARCH_WORKER_URL = 'app/search/search-worker.js';
 
 @Injectable()
 export class SearchService {
@@ -25,8 +24,13 @@ export class SearchService {
   private resultsSubject = new Subject<QueryResults>();
   get searchResults() { return this.resultsSubject.asObservable(); }
 
-  constructor(private zone: NgZone) {
-    this.worker = new WebWorkerClient(SEARCH_WORKER_URL, zone);
+  constructor(private zone: NgZone) {}
+
+  initWorker(workerUrl) {
+    this.worker = new WebWorkerClient(new Worker(workerUrl), this.zone);
+  }
+
+  loadIndex() {
     const ready = this.ready = this.worker.sendMessage<boolean>('load-index').publishLast();
     // trigger the index to be loaded immediately
     ready.connect();

aio/src/app/shared/web-worker.ts

@@ -14,18 +14,16 @@ export interface WebWorkerMessage {
 }
 
 export class WebWorkerClient {
-  worker: Worker;
-  private messageId = 0;
+  private nextId = 0;
 
-  constructor(url: string, private zone: NgZone) {
-    this.worker = new Worker(url);
+  constructor(private worker: Worker, private zone: NgZone) {
   }
 
   sendMessage<T>(type: string, payload?: any): Observable<T> {
 
     return new Observable<T>(subscriber => {
 
-      const id = this.messageId++;
+      const id = this.nextId++;
 
       const handleMessage = (response: MessageEvent) => {
         const {type: responseType, id: responseId, payload: responsePayload} = response.data as WebWorkerMessage;