在具有字符串值的提供程序上使用 SpyOn

问题描述

我有一个要测试的课程。该类有一个服务注入如下：

 constructor(private actions$: Actions,@Inject('NotificationHandlerService') private notificationService: INotificationHandlerService) {}

在 spec.ts 中，我只是使用一个值提供了它，因为我只想测试显示函数是否被调用：

  beforeEach(() => {
    Testbed.configureTestingModule({
      providers: [
        provideMockActions(() => actions$),RequirementNotificationsEffects,{
          provide: 'NotificationHandlerService',useValue: {
            display: () => {}
          }
        },provideMockStore({ initialState: requirementinitialState})
      ],});

    reqNotificationEffects = Testbed.inject(RequirementNotificationsEffects);
  });

然后我正在测试显示函数是否被调用，但是我在运行测试时收到一个错误，指出 Cannot spyOn on a primitive value; string given 测试：

    it('Call notification service to display message to user.',() => {
      const testOwner = new OwnerGroupReference({name: 'Test Owner'}) ;
      const action = reqActions.removeOwnersWithSubmission({ owners: [{testOwner}]});
      const notificationdisplaySpy = jest.spyOn('NotificationHandlerService','display');

      actions$ = hot("-a",{ a: action });

      expect(reqNotificationEffects.removeOwners$).toSatisfyOnFlush(() => {
        expect(notificationdisplaySpy).toHaveBeenCalled();
      });
    });

有人知道我应该做什么吗？

解决方法

应该是

 const notificationDisplaySpy = jest.spyOn(TestBed.get('NotificationHandlerService'),'display');

在您的情况下，您正在尝试更改字符串的显示处理程序

,

在 const 变量中提取 useValue

const mockService = {
  display: jest.fn();
}
beforeEach(() => {
  TestBed.configureTestingModule({
    providers: [
      provideMockActions(() => actions$),RequirementNotificationsEffects,{
        provide: 'NotificationHandlerService',useValue: mockService
      },provideMockStore({ initialState: requirementInitialState})
    ],});

  reqNotificationEffects = TestBed.inject(RequirementNotificationsEffects);
});

it('Call notification service to display message to user.',() => {
  const testOwner = new OwnerGroupReference({name: 'Test Owner'}) ;
  const action = reqActions.removeOwnersWithSubmission({ owners: [{testOwner}]});

  actions$ = hot("-a",{ a: action });

  expect(reqNotificationEffects.removeOwners$).toSatisfyOnFlush(() => {
    expect(mockService.display).toHaveBeenCalled();
  });
});

你也可以用 spyOn 来实现