How to unit test a EntityCollectionServiceBase in @ngrx/data?

Question

I have a dummy service:

export class PatientService extends EntityCollectionServiceBase<Patient> {
  constructor(serviceElementsFactory: EntityCollectionServiceElementsFactory) {
    super('Patient', serviceElementsFactory);
  }
}

I have the following test:

describe('PatientService', () => {
  let service: PatientService;

  beforeEach(() => {
    TestBed.configureTestingModule({});
    service = TestBed.inject(PatientService);
  });

  it('should be created', () => {
    expect(service).toBeTruthy();
  });
});

And it gives me:

NullInjectorError: No provider for EntityCollectionServiceElementsFactory

So I updated as follows:

describe('PatientService', () => {
  let service: PatientService;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [EntityDataModuleWithoutEffects.forRoot(entityConfig)],
      providers: [provideMockStore()],
    });
    service = TestBed.inject(PatientService);
  });

  it('should be created', () => {
    expect(service).toBeTruthy();
  });
});

But now it gives me:

NullInjectorError: No provider for ScannedActionsSubject!

How can I properly fix my test?

satanTime · Accepted Answer · 2022-08-06T10:19:10.847

Updated 2022-08-06

Because of changes in the latest version of ngrx, you need to import an empty store modules and HttpClientTestingModule.

Please check the example below:

describe('PatientService', () => {
  let service: PatientService;

  beforeEach(() => {

    TestBed.configureTestingModule({
      providers: [
        PatientService, // <- your entity collection service

        // a way to mock the store selectors
        provideMockStore(),
      ],
      imports: [
        EntityDataModule.forRoot({
          entityMetadata: {
            Patient: {}, // <- change to your entity
          },
          pluralNames: {
            Patient: 'Patients',  // <- change to your entity
          },
        }),

        // can be kept as it is if there are no more dependencies
        StoreModule.forRoot({}),
        EffectsModule.forRoot([]),
        HttpClientTestingModule,
      ],
    });
    service = TestBed.inject(PatientService);
  });

  it('should be created', () => {
    expect(service).toBeTruthy();
  });
});

Original answer

Yep, you are very close, do like that. You need to provide in testbed everything what is required for the configuration.

In our case it means that PatientService should be provided as the testing unit and EntityCollectionServiceElementsFactory should be provided as its dependency.

But EntityCollectionServiceElementsFactory has own dependencies: EntityDispatcherFactory, EntityDefinitionService, EntitySelectorsFactory and EntitySelectors$Factory. Which we don't want to provide because they might have own dependencies making our live worse.

To fix it let's simply sub EntityCollectionServiceElementsFactory.

describe('PatientService', () => {
  let service: PatientService;

  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [
        PatientService,
        {
          provide: EntityCollectionServiceElementsFactory,
          // our stub
          useValue: {
            methodsToFake: jasmine.createSpy(),
            // ....
          },
        },
      ],
    });
    service = TestBed.inject(PatientService);
  });

  it('should be created', () => {
    expect(service).toBeTruthy();
  });
});

Also to avoid the pain of mocking dependencies and its methods in future you can use ng-mocks. Then the test could looks like that:

describe('PatientService', () => {
  let service: PatientService;

  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [
        PatientService,
        {
          provide: EntityCollectionServiceElementsFactory,
          useValue: MockService(EntityCollectionServiceElementsFactory),
        },
      ],
    });
    service = TestBed.inject(PatientService);
  });

  it('should be created', () => {
    expect(service).toBeTruthy();
  });
});

I tried with ngmocks but is retrieving TypeError: Cannot destructure property 'dispatcher' of 'serviceElementsFactory.create(...)' as it is undefined. — Closca Costel Ioan, Sep 05 '20 at 22:22
Please ask a question with a code sample and share here its link. I'll check why it doesn't work. — satanTime, Sep 06 '20 at 10:42
@CloscaCostelIoan, did you ever figure out the solution to your problem? — Andrew, Aug 04 '22 at 18:25
could you submit an issue on https://github.com/help-me-mom/ng-mocks with a failing example? — satanTime, Aug 06 '22 at 08:10
I've updated the answer which includes a solution for the latest `ngrx` version. — satanTime, Aug 06 '22 at 10:20

score 2 · Answer 2 · answered Mar 02 '21 at 07:39

In case you just need to get rid of the errors, you can import all the required modules like this:

   beforeEach(() => {
     TestBed.configureTestingModule({
       imports: [HttpClientTestingModule, EffectsModule.forRoot([]), StoreModule.forRoot({}), EntityDataModule.forRoot(entityConfig)],
     });
     service = TestBed.inject(PatientService);
   });

score 0 · Answer 3 · answered May 28 '20 at 08:54

0

You will have to setup the whole data module, as you would in a "normal Angular module".

This means, providing a store, effects, and the data entity.

There could be a better way, but... i don't know ‍♂️

answered May 28 '20 at 08:54

timdeschryver

14,415
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How to unit test a EntityCollectionServiceBase in @ngrx/data?

3 Answers3

Updated 2022-08-06

Original answer

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