Testing Asynchronous Actions

    1. import { QuoteService } from './quote.service';
    2. import { QuoteComponent } from './quote.component';
    3. import { provide } from '@angular/core';
    4. import {
    5.   async,
    6.   TestBed,
    7.   fakeAsync,
    8.   tick,
    9. } from '@angular/core/testing';
    11. class MockQuoteService {
    12.   public quote: string = 'Test quote';
    14.     return Promise.resolve(this.quote);
    15.   }
    16. }
    18. describe('Testing Quote Component', () => {
    20.   let fixture;
    22.   beforeEach(() => {
    23.     TestBed.configureTestingModule({
    24.       declarations: [
    25.         QuoteComponent
    26.       ],
    27.         { provide: QuoteService, useClass: MockQuoteService }
    28.       ]
    30.     fixture = TestBed.createComponent(QuoteComponent);
    31.     fixture.detectChanges();
    32.   });
    34.   it('Should get quote', fakeAsync(() => {
    35.     fixture.componentInstance.getQuote();
    36.     tick();
    37.     fixture.detectChanges();
    38.     const compiled = fixture.debugElement.nativeElement;
    39.     expect(compiled.querySelector('div').innerText).toEqual('Test quote');
    40. });