Question

任何人都可以建议如何在spec.ts文件中测试下面的catch函数吗？

 getTemplate(){
        this._http.get('http//localhost:8080/new').map((response : Response) => response.json())).catch(this.serverError);
      }
      private serverError(err: any) {
        console.log('sever error:', err); // debug
        if(err instanceof Response) {
         //return Observable.throw(err.json().error || 'backend server error');
          // if you're using lite-server, use the following line
          // instead of the line above:
        return Observable.throw(err.text() || 'backend server error');
        }
        return Observable.throw(err || 'backend server error');
      }

Answer 1

为了测试你需要从服务器接收HttpErrorResponse。要测试这个，您可以编写一个小拦截器，并在监视响应时抛出错误，然后触发您的捕获。

查看这篇文章，它引用了如何编写拦截器以及如何在被请求时生成httperror响应，

https://medium.com/codingthesmartway-com-blog/angular-4-3-httpclient-accessing-rest-web-services-with-angular-2305b8fd654b

在下面的代码中，您还需要确保所有设置和导入都正确完成，下面的代码片段将触发httperror响应，确切地说它将是Http 404.

更新1

以下是示例测试用例文件的样子，假设您的服务名称为 YourService

import {Injectable, ReflectiveInjector} from '@angular/core';
import {async, fakeAsync, tick} from '@angular/core/testing';
import {BaseRequestOptions, ConnectionBackend, Http, RequestOptions} from '@angular/http';
import {Response, ResponseOptions} from '@angular/http';
import {MockBackend, MockConnection} from '@angular/http/testing';

import { YourService } from './serviceIndependent.service';


describe('MockBackend NameService Example', () => {
  beforeEach(() => {
    this.injector = ReflectiveInjector.resolveAndCreate([
      {provide: ConnectionBackend, useClass: MockBackend},
      {provide: RequestOptions, useClass: BaseRequestOptions},
      Http,
      YourService,
    ]);
    this.yourService = this.injector.get(YourService);
    this.backend = this.injector.get(ConnectionBackend) as MockBackend;
    this.backend.connections.subscribe((connection: any) => this.lastConnection = connection);
  });


  it('getNames() while server is not Reachable', fakeAsync(() => {
       let result: String[];
       let catchedError: any;
       this.yourService.getNames()
           .then((names: String[]) => result = names)
           .catch((error: any) => catchedError = error);
       this.lastConnection.mockRespond(new Response(new ResponseOptions({
         status: 404,
         statusText: 'URL not Found',
       })));
       tick();
       expect(result).toBeUndefined();
       expect(catchedError).toBeDefined();
     }));
});

单元测试map.catch angular4服务

1 个答案: