如何重置 Jasmine 中的间谍？

Question

I have an issue where I've set up a mock service as a spy.

 mockSelectionsService = jasmine.createSpyObj(['updateSelections']);

I then call that stub method twice, each time in a different test. The problem is that when i expect() the spy with .toHaveBeenCalledWith() the toHaveBeenCalledWith method also contains the arguments it was passed from the first test which produces a false positive on my second test.

How do I wipe/clear/reset the spyObject for my next test so that it no longer believes it as been called at all?

Initialisation of services/components

  beforeEach(() => {
    mockSelectionsService = jasmine.createSpyObj(['updateSelections']);

    TestBed.configureTestingModule({
      declarations: [QuickSearchComponent, LoaderComponent, SearchComponent, SearchPipe, OrderByPipe],
      providers: [OrderByPipe, SearchPipe, SlicePipe, {provide: SelectionsService, useValue: mockSelectionsService}],
      imports: [FormsModule, HttpClientModule]
    });


    fixture = TestBed.createComponent(QuickSearchComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();

    fixture.componentInstance.templates = mockTemplates;
    fixture.componentInstance.manufacturers = mockManufacturers;
  });

Answer 1

const spy = spyOn(somethingService, "doSomething");

spy.calls.reset();

This resets the already made calls to the spy. This way you can reuse the spy between tests. The other way would be to nest the tests in another describe() and put a beforeEach() in it too.

Answer 2

Type 1:

var myService = jasmine.createSpyObj('MyService', ['updateSelections']);

myService.updateSelections.calls.reset();

Type 2:

var myService = spyOn(MyService, 'updateSelections');

myService.updateSelections.calls.reset();

Note: Code above is tested on Jasmine 3.5

Answer 3

The mock service with the default return value can be set in the beforeEach() , but if you want to change the mocked service response later, do not call fixture.detectChanges() in beforEach, you can call it in each spec after applying required changes (if any), if you want to change the mock service response in an specific spec, then add it to that spec before the fixture.detectChanges()

  beforeEach(() => {
    serviceSpy = jasmine.createSpyObj('RealService', ['methodName']);
    serviceSpy.methodName.and.returnValue(defaultResponse);

    TestBed.configureTestingModule({
      providers: [{provide: RealService, useValue: serviceSpy }],
    ...
    })
    ...

    fixture = TestBed.createComponent(MyComponent);
    component = fixture.componentInstance;
    // do not call fixture.detectChanges() here
  });

  it('test something with default mocked service response', () => {
      fixture.detectChanges();
      ....
  });

  it('test something with a new mocked service response', () => {
      serviceSpy.methodName.and.returnValue(newResponse);
      fixture.detectChanges();
      ....
  });

Answer 4

I use it like this:

let service: anyTypeYouWant; 
let spyOnMethod: jasmine.Spy<(stringInput: string) => string>;

      beforeEach(() => {
        TestBed.configureTestingModule({});
        service = TestBed.inject(..Your_Inject..);
        spyOnMethod= spyOn(service, "myMethod");
      });


  it('Your Describe', () => {
   
    expect(service.myMethod).toHaveBeenCalled();
  })

Answer 5

add to Jelle's answer, if you got Cannot read property 'reset' of undefined when attempting mockSelectionsService.calls.reset() , try:

const spy = spyOn(somethingService, "doSomething");
spy.mockRestore(); 

reference: jest spyon demo: https://jestjs.io/docs/en/jest-object#jestspyonobject-methodname