[英]Mocking an Angular Service that has RxJS Observables for testing
[英]Mocking service calls that return observables in Angular 2?
我一直在尝试模拟一些在我的Angular应用程序中返回observable的服务调用,但我根本无法创建一个有效的observable,它将在我的代码中触发catch()
或map()
等调用。 例如:
我的服务:
create(): Observable<any> {
return this.http
.post('/api/stuff', { id: 123 })
.catch(this.handleError)
.map(this.extractData);
}
我的规格:
let authHttpMock = mock(AuthHttp);
when(authHttpMock.post('/api/stuff', { id: 123 })).thenReturn(Observable.create(observer => {
observer.error(new Error('500!'));
}));
const myService = new MyService(instance(authHttpMock));
myService.create({ id: 123 }).subscribe(
result => {
expect(result).toBeTruthy();
}
);
覆盖率分析告诉我, handleError
方法从未被执行过。 在成功观察的情况下,它也不会通过extractData
方法。
那可观察到哪里去了? 我如何返回一个适当的可观察量来测试这样的调用?
在测试代码中的某个地方我相信你需要这个代码:
AuthHttp.post('/api/stuff', {id : 123 }).subscribe(data => {});
有两种方法可以实现这一目标。
首先,在您的服务方法中,使用以下内容:
create(id:number):Obserable<any> {
let url:string = 'http://localhost:3000/api/stuff';
let data:any = {
id: id
};
return this.http.post(url, JSON.stringify(data))
.map((res:Response) => res.json());
.catch((error:any) => this.handleError(error))
}
第二种方法是,调用如下服务:
create(id:number):Obserable<any> {
let url:string = 'http://localhost:3000/api/stuff';
let data:any = {
id: id
};
return this.http.post(url, JSON.stringify(data))
.map((res:Response) => res.json());
}
当您调用服务方法时,请使用以下命令:
this._service.create(123)
.subscribe((res:any) => {
//do whatever with success
},
(error:any) => {
this.handleError(error)
});
您可以在服务中调用用于提取数据的方法this.extractData()
,而不是res.json()
,但总体而言,结果相同。
希望这可以帮助 :)
您需要先创建mockData,以便服务可以使用它。下面有2个文件。 将您的组件和服务名称分别替换为COMPONENT_NAME和SERVICE_NAME。
规格文件ts
describe('WalletComponent', () => {
let component: WalletManagementComponent;
let fixture: ComponentFixture<WalletManagementComponent>;
beforeEach(async(() => {
TestBed.configureTestingModule({
imports: [ReactiveFormsModule],
declarations: [COMPONENT_NAME],
schemas: [NO_ERRORS_SCHEMA],
providers: [
{provide: APP_BASE_HREF, useValue: '/'},
{provide: SERVICE_NAME, useClass: serviceMockData}
]
}).compileComponents();
}));
beforeEach(() => {
fixture = TestBed.createComponent(COMPONENT_NAME);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('Should create WalletComponent', () => {
expect(component).toBeTruthy();
});
});
您需要在根目录中创建名为testHelper(或任何名称)的目录
serviceMockData ts
import {Observable} from 'rxjs/Observable';
const result = {
data: [
{id: 0, name: 'Temp Data 1'},
{id: 1, name: 'Temp Data 2'},
]
};
export class serviceMockData {
constructor() {
}
getWalletAudits() {
return Observable.of(result).map(res => res);
}
}
如果您订阅错误处理程序怎么办? 例如在您的规范中:
const myService = new MyService(instance(authHttpMock));
myService.create({ id: 123 }).subscribe(
result => {
throw new Error('Not supposed to be here.')
},
err => expect(err).toBeDefined(),
);
(虽然我认为不应该这样)。
这就是我模拟失败的后端调用的方法:
// first, I provide mock http in TestBed.configure...
...
providers:
{
provide: Http,
useFactory: (backend: ConnectionBackend, options: BaseRequestOptions) => new Http(backend, options),
deps: [MockBackend, BaseRequestOptions]
},
... // other providers, like your mockAuthHttp
]
// than in the test, I tell the mockBackend to fail.
// including other stuff here to, just to show a few more things that can be done
it('should handle errors if backend doesn\'t like us', async(() => {
let service = TestBed.get(MyService);
let mockBackend = TestBed.get(MockBackend);
mockBackend.connections.subscribe((c: any) => {
if (c.request.url.indexOf('/api/stuff') !== -1) {
// you can check stuff here, like c.request.method or c.request._body
const err: ResponseError = new ResponseError('Stuff not good.');
err.status = 404;
return c.mockError(err);
}
throw new Error('Wrong url called.');
});
myService.create('whatever').subscribe((r: any) => {
throw new Error('Should not have been a success.');
},
(err: any) => {
expect(err.message).toEqual('Stuff not good.');
});
}));
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