为什么我的Jasmine单元测试中出现此错误？

我尝试通过一些示例第一次使用Jasmine进行角度单元测试，但发现了一些问题。

因此，我有这个People List Component类来实现组件的逻辑：

import { Component, OnInit, ElementRef, ViewChild } from '@angular/core';
import { EventService } from '../event.service';
import interactionPlugin, { Draggable } from '@fullcalendar/interaction';

interface WorkShiftTypes {
  name: string;
  value: string;
}

@Component({
  selector: 'app-people-list',
  templateUrl: './people-list.component.html',
  styleUrls: ['./people-list.component.css']
})
export class PeopleListComponent implements OnInit {

  people: any[];

  //cities: City[];

  workShiftTypes: WorkShiftTypes[];
  selectedShift: WorkShiftTypes;

  @ViewChild('draggable_people') draggablePeopleExternalElement: ElementRef;

  constructor(private eventService: EventService) { }

  ngOnInit(): void {
    this.eventService.getPeople().then(people => {this.people = people;});

    this.selectedShift = {name: 'Mattina', value: 'Mattina'};

    this.workShiftTypes = [
      {name: 'Mattina', value: 'Mattina'},
      {name: 'Pomeriggio', value: 'Pomeriggio'},
      {name: 'Notte', value: 'Notte'},
      {name: 'Custom', value: 'Custom'}
    ];
  }

  ngAfterViewInit() {
    console.log("PEOPLE LIST ngAfterViewInit() START !!!")
    var self = this

    new Draggable(this.draggablePeopleExternalElement.nativeElement, {
      itemSelector: '.fc-event',
      eventData: function(eventEl) {
        console.log("DRAG !!!");
        //console.log("SELECTED SHIFT: " + self.selectedShift.value);
        return {
          title: eventEl.innerText,
          startTime: "17:00",
          duration: { hours: 8 }
        };
      }
    });

  }

  createEventObject() {
    return 1;
  }

}

如您所见，它包含一个非常简单的createEventObject（）方法，该方法目前仅返回1（我想尽可能简化所有方法）。我的第一个单元测试必须测试此方法，只需检查返回值是否为1。

如您所见，前面的方法将EventService服务实例注入到构造函数中。

这是EventSerive类代码：

import { Injectable } from '@angular/core';
//import { Http } from '@angular/http';
import { HttpClientModule, HttpClient } from '@angular/common/http'

@Injectable()
export class EventService {

  private events = [
    {id: 1, title: 'All Day Event', start: '2017-02-01'},
    {id: 2, title: 'Long Event', start: '2017-02-07', end: '2017-02-10'},
    {id: 3, title: 'Repeating Event', start: '2017-02-09T16:00:00'},
  ];

  private people = [
    {id: 1, name: "PERSONA 1"},
    {id: 2, name: "PERSONA 2"},
    {id: 3, name: "PERSONA 3"},
    {id: 4, name: "PERSONA 4"},
    {id: 5, name: "PERSONA 5"},
  ]


  constructor(private http: HttpClient) {}

  /*
  getEvents(): Promise<any[]> {
    return this.http.get('assets/json_mock/calendarevents.json')
      .toPromise()
      .then(res => JSON.parse(JSON.stringify(res)).data)
      .then(res => {
        console.log(res);
        // you returned no value here!
        return res;
      })
  }
  */

getEvents(): Promise<any[]> {
  return Promise.all(this.events)
  .then(res => {
    console.log(res);
    // you returned no value here!
    return res;
  })
}

addEvent(event) {
  //this.events.push(event);
  //console.log("EVENT:")
  //console.log(event.event.title);
  console.log(event.event.start);
  console.log(event);
  const newEvent = {id: 5, title: event.event.title, start: event.event.start, end: event.event.end};
  this.events.push(newEvent);

  console.log(this.events);

}

  getPeople(): Promise<any[]> {
    return Promise.all(this.people)
        .then(res => {
          console.log(res);
          return res;
        })
  }

}

如您所见，此方法本身将另一个对象注入到构造函数中（HttpClient执行HTTP请求）。

好的，所以现在我想在我的单元测试中实现createEventObject（）方法测试。所以我有这个people-list.component.spec.ts文件：

import {async, ComponentFixture, TestBed} from '@angular/core/testing';
import { PeopleListComponent } from "./people-list.component"
import { EventService } from '../event.service';
import {HttpClientTestingModule} from '@angular/common/http/testing';

describe('people-list', () => {
    let component: PeopleListComponent;
    let fixture: ComponentFixture<PeopleListComponent>;
    let eventServiceSpy : jasmine.SpyObj<EventService>;
        beforeEach(async(() => {
          const eventServiceSpyObj = jasmine.createSpyObj('EventService',['getPeople'])

          TestBed.configureTestingModule({
              declarations: [PeopleListComponent],
              imports: [HttpClientTestingModule],
              providers : [{ provide : EventService, useValue : eventServiceSpyObj }]

        });

        // Create a testing version of my PeopleListComponent:
        fixture = TestBed.createComponent(PeopleListComponent);
        eventServiceSpy = TestBed.inject(EventService);
        component = fixture.componentInstance;
        fixture.detectChanges();
    }));

    it('createEventObject()  return 1', () => {
        expect(component.createEventObject()).toBe(1)
    })
})

我绝对不确定它在逻辑上是否正确...

问题是，目前IDE在此行给我一个错误：

eventServiceSpy = TestBed.inject(EventService);

错误是：

Type 'EventService' is not assignable to type 'SpyObj<EventService>'.
  Type 'EventService' is not assignable to type '{ getEvents: (() => Promise<any[]>) & Spy<() => Promise<any[]>>; addEvent: ((event: any) => void) & Spy<(event: any) => void>; getPeople: (() => Promise<any[]>) & Spy<...>; }'.
    Types of property 'getEvents' are incompatible.
      Type '() => Promise<any[]>' is not assignable to type '(() => Promise<any[]>) & Spy<() => Promise<any[]>>'.
        Type '() => Promise<any[]>' is missing the following properties from type 'Spy<() => Promise<any[]>>': and, calls, withArgsts(2322)

怎么了？如何正确测试组件方法？