HeroService returns an empty Observable, if the requested hero can't be found

diff --git a/src/app/hero.service.spec.ts b/src/app/hero.service.spec.ts
index 082791a..0ec21de 100644 (file)
--- a/src/app/hero.service.spec.ts
+++ b/src/app/hero.service.spec.ts
@@ -1,12 +1,35 @@
-import { TestBed } from '@angular/core/testing';
+import { TestBed} from '@angular/core/testing';
+import { TestScheduler } from 'rxjs/testing';
 
 import { HeroService } from './hero.service';
+import { Hero } from './hero';
+import {map} from 'rxjs/operators';
 
 describe('HeroService', () => {
-  beforeEach(() => TestBed.configureTestingModule({}));
+  let service: HeroService;
+  let scheduler: TestScheduler;
+
+  beforeEach(() =>  {
+    TestBed.configureTestingModule({});
+    service = TestBed.inject(HeroService);
+    scheduler = new TestScheduler(((actual, expected) => {
+      expect(actual).toEqual(expected);
+    }));
+  });
 
   it('should be created', () => {
-    const service: HeroService = TestBed.get(HeroService);
     expect(service).toBeTruthy();
   });
+
+  it('get for id=0 should return an empty Observable', () =>
+    scheduler.run(({expectObservable}) => {
+      expectObservable(service.getHero(0)).toBe('(|)');
+    })
+  );
+
+  it('get for id=11 should return an Observable, that contains the hero with id 11', () =>
+    scheduler.run(({expectObservable}) => {
+      expectObservable(service.getHero(11)).toBe('(a|)', { a: { id: 11, name: 'Dr Nice' }});
+    })
+  );
 });

diff --git a/src/app/hero.service.ts b/src/app/hero.service.ts
index 9003fe1..1db6072 100644 (file)
--- a/src/app/hero.service.ts
+++ b/src/app/hero.service.ts
@@ -1,5 +1,5 @@
 import { Injectable } from '@angular/core';
-import { Observable, of } from 'rxjs';
+import { Observable, of, EMPTY } from 'rxjs';
 import { Hero } from './hero';
 import { HEROES } from './mock-heroes';
 import { MessageService } from './message.service';
@@ -19,6 +19,11 @@ export class HeroService {
 
   getHero(id: number): Observable<Hero> {
     this.messageService.add(`HeroService: fetched hero id=${id}`);
-    return of(HEROES.find(hero => hero.id === id));
+    const found: Hero | undefined = HEROES.find(hero => hero.id === id);
+    if (found === undefined) {
+      return EMPTY;
+    } else {
+      return of(found);
+    }
   }
 }