使用 flush() 方法时：“响应类型不支持自动转换为 JSON。”

Question

当我使用flush()测试 HTTP 请求的方法时，出现此错误：

响应类型不支持自动转换为 JSON。

你能不能解释一下flush()方法的目标。我真的不明白。

问题并没有真正解决。我们必须像这样向“it”函数添加 async() 方法：“it('should get the post', async(() => {

import { TestBed } from '@angular/core/testing';
import {HttpClientTestingModule, HttpTestingController} from "@angular/common/http/testing"
import { DataService } from './data.service';
import { Observable } from 'rxjs';
import { Post } from './post.model';
import { HttpClientModule } from '@angular/common/http';

describe('DataService', () => {

  let service: DataService
  let  httpTestingController: HttpTestingController
  let attemptedPost : Post;
  const post = {
    userId: 1,
    id: 1,
    title: "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
    body: "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"
  };


  beforeEach(() => { TestBed.configureTestingModule({

    imports : [HttpClientTestingModule,HttpClientModule],
    providers : [DataService]
  });

    service = TestBed.get(DataService);
    httpTestingController = TestBed.get(HttpTestingController)
});

  it('should be created', () => {
    expect(service).toBeTruthy();
  });

  it('should get the post', () => {


    service.getPosts().subscribe( (postRetrieved) => {

      attemptedPost=postRetrieved;
    }); 

   const req =  httpTestingController.expectOne('https://jsonplaceholder.typicode.com/posts/1');
   req.flush(attemptedPost);
   // expect(attemptedPost).toEqual(post);

  });
});

Answer 1

你的错误是该 subscribe方法是async所以你尝试这个：

service.getPosts().subscribe( (postRetrieved) => {

      attemptedPost=postRetrieved;

   const req =  httpTestingController.expectOne('https://jsonplaceholder.typicode.com/posts/1');
   req.flush(attemptedPost);
   // expect(attemptedPost).toEqual(post);

});