Creating Test Cases for Service Response Validation

Question

Creating Test Cases for Service Response Validation

I am currently attempting to unit test an API within my ngOnInit method. The method is responsible for making a call to the service in order to fetch details. If the details are not undefined, an array called 'shoeDataResponse' of type *shoeData [] will be populated with these details and returned as the response.

*shoeDataResponse: shoeData[];

Below is the implementation of the method:

 ngOnInit(): void {
    this.shoeService.getShoeData().subscribe((shoeDetails) => {
      if (shoeDetails != undefined) {
        this.shoeDataResponse = shoeDetails;
      }
    });
  }

I am uncertain if this is the correct approach, but here is what I have attempted in the spec file:

  it('should return data if defined',  waitForAsync(() => { 
let shoeDataResponse = [
      {
        mCompanyIDEntity: {
          mbranchID: '108020',
          misShippingItem: true,
          mIsBranchNumber: false,
        },
        companyName: 'SOME COMPANY',
        shoeBalance: 1250.00,
        orderDate: '',
        mAccountHolder: false,
      },
    ];

    spyOn(ShoeService, 'getShoeData').and.returnValue(of(shoeDataResponse));
    component.ngOnInit();
    expect(component).toBeTruthy();
  }));

Upon running the test, I encounter an error stating, "Argument of type '"getShoeData"' is not assignable to parameter of type '"prototype"'."

Any assistance on resolving this issue would be highly appreciated. Thank you!!!

javascript angular typescript unit-testing frontend

Answer 1

Answer №1

It appears that the issue lies in how you are setting up the spy for the getShoeData function. Rather than directly spying on the service class, you need to create a spy on the instance of the service that is injected into the component.

Start by creating an instance of the service:

  let shoeService: ShoeService; // initialize the instance

  beforeEach(async () => {
    await TestBed.configureTestingModule({
      declarations: [ComponentName],
      providers: [ShoeService], // include the service in the providers
    }).compileComponents();
  });

  beforeEach(() => {
    fixture = TestBed.createComponent(ComponentName);
    component = fixture.componentInstance;
    shoeService = TestBed.inject(ShoeService); // add this line to instantiate ShoeService
  });

Next, in your test, remember to spy on the shoeService instance rather than the ShoeService class method

spyOn(shoeService, 'getShoeData').and.returnValue(of(shoeDataResponse));

Answer 2

It appears that the issue lies in how you are setting up the spy for the getShoeData function. Rather than directly spying on the service class, you need to create a spy on the instance of the service that is injected into the component.

Start by creating an instance of the service:

  let shoeService: ShoeService; // initialize the instance

  beforeEach(async () => {
    await TestBed.configureTestingModule({
      declarations: [ComponentName],
      providers: [ShoeService], // include the service in the providers
    }).compileComponents();
  });

  beforeEach(() => {
    fixture = TestBed.createComponent(ComponentName);
    component = fixture.componentInstance;
    shoeService = TestBed.inject(ShoeService); // add this line to instantiate ShoeService
  });

Next, in your test, remember to spy on the shoeService instance rather than the ShoeService class method

spyOn(shoeService, 'getShoeData').and.returnValue(of(shoeDataResponse));

Creating Test Cases for Service Response Validation

Answer №1

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