Testing Effects: Testing the Error Case

import { Injectable } from "@angular/core";
import { Actions, createEffect, ofType } from "@ngrx/effects";
import { catchError, map, mergeMap, of } from "rxjs";
import { Product } from "src/app/app.interfaces";
import { ProductsService } from "src/app/products.service";
import { loadProductsAction, getProductsAction, getErrorAction } from "./products.actions";
@Injectable()
export class ProductsEffects {
  constructor(
    private actions$: Actions,
    private productsService: ProductsService
  ) { }
  loadProducts$ = createEffect(() => {
    return this.actions$.pipe(
      ofType(loadProductsAction),
      mergeMap(action => this.productsService.getProducts().pipe(
        map((products: Product[]) => getProductsAction({ products })),
        catchError(() => of(getErrorAction()))
      ))
    )
  })
}

import { TestBed } from '@angular/core/testing';
import { Actions } from '@ngrx/effects';
import { provideMockActions } from '@ngrx/effects/testing';
import { TestScheduler } from 'rxjs/testing';
import { Product } from 'src/app/app.interfaces';
import { ProductsService } from 'src/app/products.service';
import {
  getProductsAction,
  loadProductsAction,
} from './products.actions';
import { ProductsEffects } from './products.effects';
describe('ProductsEffects: loadProducts$', () => {
  let effects: ProductsEffects;
  let actions$: Actions;
  let productsServiceSpy = jasmine.createSpyObj('ProductsService', [
    'getProducts',
  ]);
  let testScheduler: TestScheduler;
  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [
        ProductsEffects,
        provideMockActions(() => actions$),
        { provide: ProductsService, useValue: productsServiceSpy },
      ],
    });
    effects = TestBed.inject(ProductsEffects);
    testScheduler = new TestScheduler((actual, expected) => {
      expect(actual).toEqual(expected);
    });
  });
  it('should handle loadProductsAction and return getProductsAction on success', () => {
    const products: Product[] = [
      {
        id: 1,
        title: 'The Angular Masterclass',
        author: 'Educative',
        description: 'Learn all about Angular',
        imgUrl: '../assets/img/the-angular-masterclass.jpg',
        quantity: 124,
        price: 24.38,
        cart: 0,
      },
    ];
    let action = loadProductsAction();
    let originalResponse = getProductsAction({ products });
    testScheduler.run(({ hot, cold, expectObservable }) => {
      actions$ = hot('-a', { a: action });
      let mockResponse = cold('-b|', { b: products });
      productsServiceSpy.getProducts.and.returnValue(mockResponse);
      expectObservable(effects.loadProducts$).toBe('--c', { c: originalResponse });
    });
  });
  it('should handle loadProductsAction and return getErrorAction action on failure', () => {
  });
});