Mocking a repository in Nest JS - nestjs

Question

According to the documentation, we can use providers in the testing module to provide a mocked version of our repo. I ended up having this code for my test:
describe('UserController', () => {
let userController: UserController
beforeEach(async () => {
const app: TestingModule = await Test.createTestingModule({
controllers: [UserController],
providers: [
UserService,
{
provide: getRepositoryToken(User),
useValue: {
//
// Trying everything here
getUsers: () => {
return Promise.resolve(['user1', 'user2'])
},
find: () => {
return Promise.resolve(['user1', 'user2'])
},
findAll: () => {
return Promise.resolve(['user1', 'user2'])
},
//
},
},
],
}).compile()
userController = app.get<UserController>(UserController)
})
describe('root', () => {
it('should return Users', () => {
expect(userController.getUsers()).toEqual(['user1', 'user2'])
})
})
})
And the controller/repository are quite straightforward:
#Controller()
export class UserController {
constructor(private readonly userService: UserService) {}
#Get()
async getUsers(): Promise<User[]> {
return this.userService.findAll()
}
#Post()
addNewUser(#Body() user: Partial<User>): Promise<number> {
return this.userService.create(user)
}
}
#Injectable()
export class UserService {
constructor(
#InjectRepository(User)
private usersRepository: Repository<User>
) {}
findAll(): Promise<User[]> {
return this.usersRepository.find()
}
findOne(id: string): Promise<User> {
return this.usersRepository.findOne(id)
}
async remove(id: string): Promise<void> {
await this.usersRepository.delete(id)
}
async create(user: Partial<User>): Promise<number> {
return (await this.usersRepository.save(user)).id
}
}
When I run the tests, userController.getUsers() returns an empty object:
● UserController › root › should return Users
expect(received).toEqual(expected) // deep equality
Expected: ["user1", "user2"]
Received: {}
38 | describe('root', () => {
39 | it('should return Users', () => {
> 40 | expect(userController.getUsers()).toEqual(['user1', 'user2'])
| ^
41 | })
42 | })
43 | })
at Object.<anonymous> (user/user.controller.spec.ts:40:41)
What might be the issue?

Answer 1

The issue was quite silly - getUsers returns a promise, so I had to do something like this instead:
describe('root', () => {
it('should return Users', async () => {
const res = await userController.getUsers()
expect(res).toEqual(['user1', 'user2'])
})
})