How to mock @Select in ngxs when using a mock store

[splincode]

I am using ngxs for state handling in angular, and I am trying to test our components as units, so preferably only with mock stores, states etc.

What we have in our component is something like:

export class SelectPlatformComponent {

  @Select(PlatformListState) platformList$: Observable<PlatformListStateModel>;

  constructor(private store: Store, private fb: FormBuilder) {
    this.createForm();
    this.selectPlatform();
  }

  createForm() {
    this.selectPlatformForm = this.fb.group({
      platform: null,
    });
  }

  selectPlatform() {
    const platformControl = this.selectPlatformForm.get('platform');
    platformControl.valueChanges.forEach(
      (value: Platform) => {
        console.log("select platform " + value);
        this.store.dispatch(new PlatformSelected(value));
      }
    );
  }

}

And our fixture setup looks like this, so we can check calls on the store:

describe('SelectPlatformComponent', () => {
  let component: SelectPlatformComponent;
  let fixture: ComponentFixture<SelectPlatformComponent>;
  let store: Store;

  beforeEach(async(() => {
    const storeSpy = jasmine.createSpyObj('Store', ['dispatch']);
    TestBed.configureTestingModule({
      imports: [ReactiveFormsModule],
      declarations: [SelectPlatformComponent],
      providers: [{provide: Store, useValue: storeSpy}]

    })
      .compileComponents();
    store = TestBed.get(Store);
  }));

But when we run this, we get the following error:

Error: SelectFactory not connected to store!
    at SelectPlatformComponent.createSelect (webpack:///./node_modules/@ngxs/store/fesm5/ngxs-store.js?:1123:23)
    at SelectPlatformComponent.get [as platformList$] (webpack:///./node_modules/@ngxs/store/fesm5/ngxs-store.js?:1150:89)
    at Object.eval [as updateDirectives] (ng:///DynamicTestModule/SelectPlatformComponent.ngfactory.js:78:87)
    at Object.debugUpdateDirectives [as updateDirectives] (webpack:///./node_modules/@angular/core/fesm5/core.js?:11028:21)
    at checkAndUpdateView (webpack:///./node_modules/@angular/core/fesm5/core.js?:10425:14)
    at callViewAction (webpack:///./node_modules/@angular/core/fesm5/core.js?:10666:21)
    at execComponentViewsAction (webpack:///./node_modules/@angular/core/fesm5/core.js?:10608:13)
    at checkAndUpdateView (webpack:///./node_modules/@angular/core/fesm5/core.js?:10431:5)
    at callWithDebugContext (webpack:///./node_modules/@angular/core/fesm5/core.js?:11318:25)
    at Object.debugCheckAndUpdateView [as checkAndUpdateView] (webpack:///./node_modules/@angular/core/fesm5/core.js?:10996:12)

I could enable the entire ngxs module for this, but then I would need to create services mocks to inject into state objects, which I do not like because I am then not testing the component in isolation anymore. I tried to create a mock SelectFactory, but it seems it is not exported from the module.

Is there a way to mock the SelectFactory, or inject some mocks into the platformList$ directly? Other suggestions?

PS: I also asked this on stackoverflow, but no real answer was given: https://stackoverflow.com/questions/51082002/how-to-mock-select-in-ngxs-when-using-a-mock-store

[marcus-sa]

You figured this out yet?
It's crazy that the NGXS team haven't provided proper test utilities for their library.

[splincode]

@marcus-sa you can help us with it? PR please

[marcus-sa]

@splincode I'll give it a try :)

[splincode]

@aymeric-duchein Could you help with this issue?