Testing an Angular 5 HTTP call

http-test.spec.ts

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

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

describe('AppComponent', () => {
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [ HttpClientModule, HttpClientTestingModule ]
    });
  }));

  // Clear the http controller
  afterEach(inject([HttpTestingController], (backend: HttpTestingController) => {
    backend.verify();
  }));

  it('should mock an http call', async(inject([HttpClient, HttpTestingController], (http, backend) => {
    http.get('/test').subscribe(
      data => {
        expect(data).toBeTruthy();
      },
      error => {}
    );

    backend.match({
      url: '/test',
      method: 'GET'
    })[0].flush({'fu': 'bar'});
  })));
});