Test for provider

test-provider.spec.ts

import { TestBed, inject, fakeAsync, tick } from '@angular/core/testing';
import { YourService } from './your.service';

describe('Provider: YourService', () => {

  //Arrange
  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [
        { provide: YourService, useClass: YourService },
      ]
    });
  });

  it('should be created', inject([YourService], (service: YourService) => {
    expect(service).toBeTruthy();
  }));

  describe("Test for doSomething", ()=>{

    it('should dataResponse be defined', inject([YourService], fakeAsync((service: YourService) => {
      let dataResponse, dataError;
      service.doSomething()
      .then(response =>{
        dataResponse = response;
      })
      .catch(error=>{
        dataError = error;
      })
      tick();
      expect(dataResponse).toBeDefined();
    })));

 });

});