使用 angular 进行测试时如何使用 'ngrx effects' 触发错误

Question

这是我的效果：

 getAssessmentPeriods$: Observable<Action> = createEffect(() =>
        this.actions$.pipe(
            ofType(courseAttributeActions.getAssessmentPeriod_CR),
            switchMap(() => this.courseAttributeService.getAssessmentPeriods()
                .pipe(
                    map((value: any) => {
                        return courseAttributeActions.getAssessmentPeriodSuccess_CR({ payload: value });
                    }),
                    catchError(error => of(courseAttributeActions.LoadFailure_CR(error)))
                ))
        ));

规范文件：快乐场景工作正常：

it('should return a cold observable of getAssessmentPeriodSuccess_CR', () => {

        const fakeData: any = [];

        const start = courseAttributeActions.getAssessmentPeriod_CR();
        const completion = courseAttributeActions.getAssessmentPeriodSuccess_CR({ payload: fakeData });

        jest.spyOn(service, 'getAssessmentPeriods').mockImplementation(() => of(fakeData));

        actions = hot('--a-', { a: start });
        const expected = cold('--(b)', { b: completion });

        expect(effects.getAssessmentPeriods$).toBeObservable(expected);

    });

规范文件：错误场景不起作用：

 it('should return a cold observable of LoadFailure_CR error ', () => {

        const errors: any = throwError((new Error('Network error')));

        const start = courseAttributeActions.getAssessmentPeriod_CR();
        const completionError = courseAttributeActions.LoadFailure_CR({error:errors});

        jest.spyOn(service, 'getAssessmentPeriods').mockImplementation(() => of(errors));

        actions = hot('--a-', { a: start });
        const expected = cold('--(b)', { b: completionError });

        expect(effects.getAssessmentPeriods$).toBeObservable(expected);

    });

在错误情况下如何触发服务中的error？实际上我是从间谍发来的。但我仍然收到成功消息。

控制台出现如下错误：

- Expected
    + Received

    @@ -4,14 +4,14 @@
          "notification": Notification {
            "error": undefined,
            "hasValue": true,
            "kind": "N",
            "value": Object {
    -         "error": Observable {
    +         "payload": Observable {
                "_isScalar": false,
                "_subscribe": [Function anonymous],
              },
    -         "type": "[candidate-registration-management] LoadFailure_CR",
    +         "type": "[candidate-registration-management_CR] getAssessmentPeriodSuccess",
            },
          },
        },
      ]

      69 |         const expected = cold('--(b)', { b: completionError });
      70 |
    > 71 |         expect(effects.getAssessmentPeriods$).toBeObservable(expected);

如何修复错误？是否真的需要为 1 个效果编写 2 个单独的 'it' 函数？寻求帮助。提前致谢。

Answer 1

throwError 等同于

return new Observable(subscriber => subscriber.error(error));

因此，通过执行 mockImplementation(() => of(errors));，您将拥有一个可观察对象（例如 of），它会发出另一个可观察对象（next 通知）。

为了使错误发生，getAssessmentPeriods observable 必须发出 error 通知，所以我认为您可以通过以下方式解决它：

.mockImplementation(() => errors)

使用 angular 进行测试时如何使用 'ngrx effects' 触发错误

How to trigger an error with 'ngrx effects' when testing with angular

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