How write Jasmine testcase for HttpClient post method which return promise

Question

The below is AbcService.ts file, I want to test this service file whether it is retuning specified request/data It is calling 1 time as expected but rejecting the promise not returning anything the error i'm getting is HttpClient.post received a call with arguments but all configured strategies specify other arguments.
please help? How to write test cases in jasmine for above code?

@injectable({
provideIn:'root'
})
export class AbcService{
constructor(private client:HttpClient){}

async imbook(json: string): Promise<any>{
  let search!: SearchDefinition;
     search = Object.assign(JSON.parse(json));
   const httpOptions={
   headers: new HttpHeaders({
   'content-Type':'application/json',
   'Access-Control-Allow-Origin':'*'
}) 
};
const req = 
this.client.post("https://abc.zone/api/data",search,httpOptions).pipe(timeout(360000))
.toPromise()
await req;     
return req;
}
}

here is test setup in spec file

describe('AbcService',()=>{
let service: AbcService;
let httpclientspy: jasmine.spyObj<HttpClient>;
let httpclientspyobj: jasmine.createSpyObj('HttpClient',['post']);
});
beforeEach(()=>TestBed.configureTestingModule({
imports: [HttpClientTestingModule],
providers:[AbcService,{
           provide: HttpClient, useValue: httpclientspyobj   
}]
}));
beforeEach(() =>{
    service = TestBed.inject(AbcService);
    client = TestBed.inject(HttpClient);
    httpclientspy = TestBed.inject(HttpClient) as jasmine.SpyObj<HttpClient> 
});

here is the testcase.

it('it should call http post method and return req',()=>{
const json= '{"id":"1","count":"5","name":"book name"}';

const httpOptions={
headers: new HttpHeaders({
'Content-Type':'application/json',
 'Access-Control-Allow-Origin':'*'})
};

httpclient.post.withArgs('https://abc.zone/api/data',json,httpOptions).and.resolveTo();

service.imbook(json);

expect(httpclientspy.post).toHavebeenCalledTimes(1);
})

It is calling 1 time as expected but rejecting the promise not returning anything the error i'm getting is HttpClient.post received a call with arguments but all configured strategies specify other arguments.
please help? How to write test cases in jasmine for above code?

Answer 1

You can try this:

describe('AbcService',()=>{
  let service: AbcService;
  let httpTestingController: HttpTestingController;

  beforeEach(()=>TestBed.configureTestingModule({
    imports: [HttpClientTestingModule],
    providers:[AbcService]
  }));

  beforeEach(() =>{
    service = TestBed.inject(AbcService);
    client = TestBed.inject(HttpTestingController);
  });
  
  // !! add async here
  it('it should call http post method and return req', async ()=>{
    const json= '{"id":"1","count":"5","name":"book name"}';

    const httpOptions={
    headers: new HttpHeaders({
      'Content-Type':'application/json',
      'Access-Control-Allow-Origin':'*'})
    };
    
    // !! get a handle on the promise
    const promise = service.imbook(json);
    
    // !! get a handle on the http request in flight
    const req = client.expectOne(request => request.method === 'POST');
    // !! send this response to the http call
    req.flush({});
    // !! await the promise
    const result = await promise;
    // !! expect the result to be what we sent
    expect(result).toEqual({});
});

To learn more about testing services with Http calls, refer to this link: https://testing-angular.com/testing-services/#testing-a-service-that-sends-http-requests.