How to mock @Injectable service in supertested controller?

[tkroll]

Hello! These are truncated examples, but I have a service:

import { Injectable } from '@tsed/common'
import { CHAPTER_REPOSITORY } from '../repository/ChapterRepository'
import { Inject } from '@tsed/di'
import { Chapter } from '../entity/Chapter'

@Injectable()
export class ChapterService {
  @Inject(CHAPTER_REPOSITORY)
  protected repository: CHAPTER_REPOSITORY

  async findChapters(bookId?: number): Promise<Chapter[]> {
    return await this.repository.findChapters(bookId)
  }
}

That is injected into a controller:

import { Controller } from '@tsed/di'
import { Get } from '@tsed/schema'
import { ChapterService } from '../service/ChapterService'
import { QueryParams } from '@tsed/common'
import { Chapter } from '../entity/Chapter'

@Controller('/chapter')
export class ChapterController {
  constructor(private chapterService: ChapterService) {
  }

  @Get('/')
  async findChapters(@QueryParams('bookId') bookId?: number): Promise<Chapter[]> {
    return await this.chapterService.findChapters(bookId)
  }
}

I'm trying to supertest this controller:

import { PlatformTest } from '@tsed/common'
import SuperTest from 'supertest'
import { Server } from '../../Server'
import { Chapter } from '../../entity/Chapter'

const data = {
  id: 2,
  bookId: 4,
  timestamp: 1650996201,
  name: 'First Day At Work',
}

const entity = new Chapter()
Object.assign(entity, data)

jest.mock('../../service/ChapterService', () => ({
  findChapters: jest.fn().mockResolvedValue([ entity ])
}))

describe('ChapterController', () => {

  let request: SuperTest.SuperTest<SuperTest.Test>

  beforeAll(PlatformTest.bootstrap(Server))
  beforeAll(async() => {
    request = SuperTest(PlatformTest.callback())
  })
  afterAll(PlatformTest.reset)

  describe('GET /rest/chapter', () => {
    it('Get All Chapters', async() => {
      const response = await request.get('/rest/chapter').expect(200)
      expect(typeof response.body).toEqual('object')
    })
  })
})

This fails with:

 FAIL  src/controller/__tests__/ChapterController.ts (5.83 s)
  ChapterController
    GET /rest/chapter
      ✕ Get All Chapters

  ● ChapterController › GET /rest/chapter › Get All Chapters

    UNDEFINED_TOKEN_ERROR: Unable to inject dependency. Given token is undefined. Have you enabled emitDecoratorMetadata in your tsconfig.json or decorated your class with @Injectable, @Service, ... decorator ?

    ChapterController->constructor(chapterService: undefined)

emitDecoratorMetadata is set true in tsconfig.json

How can I get this working?

Thanks

[Romakita]

Hello @tkroll

It's because, you return a plain object javascript and not a class. So the DI doesn't resolve the correct symbol and it explain why you have this message because it's similar to not have theses compilation options.

I suggest you to not use jest.mock.

Here is the solution:

import { PlatformTest } from '@tsed/common'
import SuperTest from 'supertest'
import { Server } from '../../Server'
import { Chapter } from '../../entity/Chapter'

const entity = new Chapter()
Object.assign(entity,  {
  id: 2,
  bookId: 4,
  timestamp: 1650996201,
  name: 'First Day At Work',
})

describe('ChapterController', () => {

  let request: SuperTest.SuperTest<SuperTest.Test>

  beforeAll(PlatformTest.bootstrap(Server))
  beforeAll(async() => {
    const service = PlatformTest.get(ChapterService)
    
    jest.spyOn(service, "findChapters").mockResolvedValue([ entity ])
    request = SuperTest(PlatformTest.callback())
  })
  afterAll(PlatformTest.reset)

  describe('GET /rest/chapter', () => {
    it('Get All Chapters', async() => {
      const response = await request.get('/rest/chapter').expect(200)
      expect(typeof response.body).toEqual('object')
    })
  })
})

[tkroll]

@Romakita Perfect. Thanks again for the help.