Angular 2 - 单元测试 : How to expect throw new Error ("error") from component

Question

我通过 jasmine + karma 为 angular 2 编写单元测试。
我有组件检查异常并抛出错误。并编写单元测试来检查这种情况。
但是我在触发 fixture.detectChanges();

时看到一条错误消息

'Unhandled Promise rejection:'

我该如何解决这个案例。请参阅下面的我的代码。谢谢

**MyComponent.ts**

ngOnInit() {
  if (this.erorr) {
      throw new Error("error");
  }
}

**AppModule.ts**

class MyErrorHandler extends ErrorHandler {
  handleError(error) {
     console.log("error");
     location.href="/error"
  }
}

和一个单元测试文件

**MyComponent.spec.ts**

describe('My Management Test', () => {
  beforeEach(async( () => {
        TestBed.configureTestingModule({
            declarations: [ MyComponent ],
            providers: provider,
            schemas: [CUSTOM_ELEMENTS_SCHEMA],
            imports: imports
        }).compileComponents().then(() => {});
    }));

    beforeEach(inject([MockBackend], (mockBackend: MockBackend) => {
        Connection(mockBackend);
        fixture = TestBed.createComponent(MyComponent);
    }));

   it('Go to contact management page', (done) => {
        fixture.detectChanges();
        //Need to check if component throw error
    });
})

Answer 1

试试这个:

expect(() => fixture.detectChanges())
   .toThrowError(TypeError /*or another error type\*/);