Unit test Angular services that use HttpClient

Services to be tested:

import { Injectable } from '@angular/core';
import {HttpClient} from '@angular/common/http';

@Injectable(a)export class BookManageService {
  private API_PATH = 'https://www.googleapis.com/books/v1/volumes';
  constructor(private http: HttpClient){}searchBooks(queryTitle: string) {
    return this.http.get(`The ${this.API_PATH}? q=${queryTitle}`); }}Copy the code

Unit test code:

import { TestBed } from '@angular/core/testing';
import { BookManageService } from './book-manage.service';
import { Book } from '.. /model/books';
import { of } from 'rxjs';

describe('Book Manage service'.() = > {
    let httpClientSpy: { get: jasmine.Spy };
    let bookService: BookManageService;
    beforeEach(() = > {
      httpClientSpy = jasmine.createSpyObj('HttpClient'['get']);
      bookService = new BookManageService(httpClientSpy as any);
    });
    it('should return expected books (HttpClient called once)'.() = > {

        const BOOK: Book = {
            id: 'Jerry-Book'.volumeInfo: {
              title: 'Diablo'.subtitle: 'Diablo II'.authors: ['Jerry'.'Tom'].publisher: 'SAP'.publishDate: '2020-2-2'.description: 'This is great book'.averageRating: 1.ratingsCount: 100}};const expectedBooks: Book[] = [ BOOK];
        httpClientSpy.get.and.returnValue(of(expectedBooks));
        bookService.searchBooks('Jerry').subscribe(
            books= > expect(books).toEqual(expectedBooks, 'expected books'),
        fail
      );
        expect(httpClientSpy.get.calls.count()).toBe(1.'one call');
    });
});
Copy the code

Test results: