如何对 angular 中的 BehaviorSubject 订阅进行单元测试

Question

我有一个 UserManagementService，它公开了一个 BehaviourSubject 的 Observable。

this.userSignInState$ = this.signInStateSubject.asObservable();

我在 nav 组件中订阅了 userSignInState。

constructor(public userManagementService: UserManagementService, private fb:FormBuilder, private helper:HelperService) {
    this.userSignInStateSubscription = this.userManagementService.userSignInState$.subscribe(
          (result:Result)=> {
            console.log("In nav - result from user signin state ",result);
            let subscribed:UserSigninState = result.additionalInfo;
            console.log("new user signin state received:", subscribed);
            this.userLoggedIn = subscribed.isSignedIn;
            if(subscribed.isSignedIn && subscribed['additional-info'] !== ''){
              this.profile = JSON.parse(subscribed['additional-info']) as UserProfileAPI
            }
            if(!subscribed.isSignedIn && subscribed['additional-info'] !== ''){
            //  let error:ServerResponseAPI = JSON.parse(subscribed['additional-info']) as ServerResponseAPI
              //let errorMessage:string = this.helper.userFriendlyErrorMessage(error);
              this.navEvent.emit(new NavContext(subscribed['additional-info']));
            }
          },
        (error:ServerResponseAPI)=>{
            console.log("got error from the Observable: ",error);

           let errorMessage:string = this.helper.userFriendlyErrorMessage(error);
           this.navEvent.emit(new NavContext(errorMessage));
    //       this.userloggedIn =false;
      },
      ()=>{ //observable complete
        console.log("observable completed")
        //this.userloggedIn =false;
      });
  }

我想进行单元测试nav。 spec 应该测试 component 订阅 userSignInState$ 并正确处理 Result。我该怎么做呢？由于这是一个单元测试，我不想使用真正的 UserManagementService

我写了以下规范

fit('should subscribe to user sign in state observable',()=>{
    let userManagementService = TestBed.get(UserManagementService);
    let navComponent:NavComponentComponent = component;
    console.log('component is ',navComponent);
    navComponent.userLoggedIn = false;
    let dummyUserProfile = new UserProfileAPI(new User('fn','ln','test@test.com'));
    userManagementService.signInStateSubject.next(new Result('success',(new UserSigninState(true,JSON.stringify(dummyUserProfile ))).toString));
    expect(navComponent.userLoggedIn).toBe(true)
  });

但我收到错误 Expected undefined to be true.

我不明白为什么 userLoggedIn 是未定义的。我已经在 nav class

中声明了它

export class NavComponentComponent implements OnInit  {

  userLoggedIn:boolean;
...
}

我设置在ngOnInit.

ngOnInit(){

    this.userLoggedIn = false;
  ...
}

我也将订阅逻辑移至 ngOnInit，但这也不起作用，结果相同。

Answer 1

问题出在我创建 Result 的方式上。我不应该将 .toString 与 userSignInState 一起使用。来自我在 SO、"reference to .toString without () is just a reference to that function, so if you log that you get the code for that function." 和 "toString() will not work as userSignInState doesn't have a meanigful string representation and is defaulting to [object Object]" 中发布的另一个问题。我删除了 toString 并且代码作为 additional-info 是类型 any

如何对 angular 中的 BehaviorSubject 订阅进行单元测试

how to unit test subscription to a BehaviourSubject in angular

angular-test

angular6