import { Injectable } from '@angular/core';

import { Observable } from 'rxjs/Observable';

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

export interface Person {

  name: string;

}

@Injectable()

export class PeopleService {

  constructor(private http: HttpClient) {}

  fetchPeople(): Observable<Person[]> {

    return this.http

      .get<Person[]>('/api/v1/people');

  }

}

import { TestBed, inject } from '@angular/core/testing';

import { HttpClientTestingModule, HttpTestingController } from '@angular/common/http/testing';

import { PeopleService } from './people.service';

describe('The PeopleService', () => {

  beforeEach(() => {

    TestBed.configureTestingModule({

      imports: [HttpClientTestingModule],

      providers: [

          PeopleService

      ]

    });

  });

  it('should fetch a list of people', inject(

    [PeopleService, HttpTestingController],

    (peopleService: PeopleService, httpMock: HttpTestingController) => {

    // execute the call

    peopleService

      .fetchPeople()

      .subscribe(people => {

        expect(people.length).toBe(2);

        expect(people[0].name).toBe('Juri');

      });

    const req = httpMock.expectOne('/api/v1/people', 'call to ppl api');

    expect(req.request.method).toBe('GET');

    req.flush([

      {

        name: 'xxx'

      },

      {

        name: 'xxx'

      }

    ]);

    httpMock.verify();

  }));

});