ngxs-testing.example.ts

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

export interface ZooStateModel {
  feedAnimals: string[];
}

export class FeedAnimals {
  public static type: string = '[FeedAnimals]: action';
  constructor(public animalsToFeed: string[]) {}
}

@State<ZooStateModel>({
  name: 'zoo',
  defaults: {
    feedAnimals: []
  }
})
@Injectable()
export class ZooState {

  @Action(FeedAnimals)
  feedAnimals(ctx: StateContext<ZooStateModel>, action: FeedAnimals) {
    const state = ctx.getState();
    ctx.setState({
      ...state,
      feedAnimals: [...state.feedAnimals, action.animalsToFeed]
    });
  }

}

describe('Zoo', () => {
  let store: Store;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [NgxsModule.forRoot([ZooState])]
    });

    store = TestBed.inject(Store);
  });

  it('it toggles feed', () => {
    store.dispatch(new FeedAnimals([ 'leaves', 'bark' ]));
    const feed = store.selectSnapshot(state => state.zoo.feedAnimals);
    
    expect(feed).toBe([ 'leaves', 'bark' ]);
  });
});