Nest: TypeORM test save() with a mock repository?

[kheob]

I'm submitting a...

[ ] Regression 
[ ] Bug report
[ ] Feature request
[x] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

I'm trying to write a test to test the creation of a User object and saving it to a database.

user.service.spec.ts

describe('UserService', () => {
  let service: UserService;

  beforeAll(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [
        UserService,
        {
          provide: getRepositoryToken(User),
          useClass: UserRepository,
        },
      ],
    }).compile();
    service = module.get<UserService>(UserService);
  });

  it('should be defined', () => {
    expect(service).toBeDefined();
  });

  it('can create a user', async () => {
    const userDto = new UserDto();
    userDto.email = '[email protected]';
    userDto.password = 'password123';
    const user = await service.create(userDto);
    expect(user.username).toEqual(userDto.email);
  });
});

user.service.ts

@Injectable()
export class UserService {
  constructor(
    @InjectRepository(User) private readonly userRepository: UserRepository,
  ) {}

  async create(userDto: UserDto): Promise<User> {
    const user = new User();
    user.username = userDto.email;
    user.password = userDto.password; // TODO: Need to hash this later
    return await this.userRepository.save(user);
  }
}

However it throws an error when trying to save() - How can I properly test this?

The error is:

 FAIL  src/user/user.service.spec.ts
  ● UserService › can create a user

    TypeError: Cannot read property 'save' of undefined

      at UserRepository.Object.<anonymous>.Repository.save (repository/Repository.ts:138:29)
      at UserService.<anonymous> (user/user.service.ts:17:38)
          at Generator.next (<anonymous>)
      at user/user.service.ts:19:71
          at new Promise (<anonymous>)
      at Object.<anonymous>.__awaiter (user/user.service.ts:15:12)
      at UserService.create (user/user.service.ts:33:16)
      at Object.<anonymous> (user/user.service.spec.ts:32:32)
          at Generator.next (<anonymous>)
      at user/user.service.spec.ts:7:71
          at new Promise (<anonymous>)
      at Object.<anonymous>.__awaiter (user/user.service.spec.ts:3:12)
      at Object.it (user/user.service.spec.ts:28:38)
          at new Promise (<anonymous>)
      at process._tickCallback (../internal/process/next_tick.js:68:7)

[kamilmysliwiec]

Could you show us your UserRepository class?

[kheob]

It’s just an empty class that extends Repository<User>. I’ve tried with Repository<User> and I still get the same error.

[kamilmysliwiec]

Please, provide a repository that reproduces this issue, I can't do it locally

[kheob]

@kamilmysliwiec Please try this: https://gitlab.com/kheob/nestjs-test

[BorjaRM]

I have the same problem trying to write a test for my service.

user.service.ts

@Injectable()
export class UsertService {
    constructor(
        @InjectRepository(UserEntity)
        private readonly userRepository: UserEntityRepository,        
    ) { }

    async saveUser(user: UserEntity) {
       await this.userRepository.save(user);
    }

    test() {
        this.userRepository.test();
    }
}

user.service.spec.ts

describe('UserService', () => {
  let userService: UserService;

  beforeAll(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [UserService,
        {
          provide: getRepositoryToken(UserEntity),
          useClass: UserEntityRepository,
        }],
    }).compile();
    userService = module.get<UserService>(UserService);
  });

  it('should be defined', () => {
    expect(userService).toBeDefined();
  });

  it('should save a user', async () => {
    const user = new UserEntity('test', 0);
    await userService.saveUser(user);
  });

  it('should call test method', async () => {
    userService.test();
  });

user.repository.ts

@EntityRepository(UserEntity)
@Injectable()
export class UserEntityRepository extends Repository<UserEntity> {

    test() {
        console.log('it works');
    }
}

If i try to run a test using save() or findOne() (or any other method from Repository) i get the following error:

● ConsentService › should save a user

    TypeError: Cannot read property 'save' of undefined

But if i use test() method from my custom repository (user.repository.ts) it works fine.

It looks like UserService its defined and it uses my custom repository however, when I run the test it says that the repository is undefined.

I would like to know the proper way to do this tests.

[kamilmysliwiec]

Honestly, I don' think that this issue has something to do with Nest.

[BorjaRM]

Hi @kamilmysliwiec,

Could you explain the steps that I should follow to test this service? I would like to use a test database instead of a fake repository.

I´ve been trying to do it following the documentation but I could not make it work.

Thank you.

[BrunnerLivio]

Maybe this helps you guys:

Mocking querybuilder approach:
https://github.com/typeorm/typeorm/issues/1774

Some time ago there was a similar issue, but unit testing with a real database. Created a boilerplate example for Nest 4.x.x back then, maybe you can inspire it from there.
https://github.com/BrunnerLivio/nestjs-unit-test-db-example

[apiel]

@BrunnerLivio your test in your example are integration test. You should not hit the database if you make unit test, everything should be mocked.

[vincilbishop]

For anyone that finds themselves here:

export const mockRepository = jest.fn(() => ({
  metadata: {
    columns: [],
    relations: [],
  },
}));

and

const module: TestingModule = await Test.createTestingModule({
      providers: [{ provide: getRepositoryToken(Entity), useClass: mockRepository }],
    }).compile();

[woutrbe]

@vincilbishop does the save method work with this? I’ve tried this and still getting errors that save is undefined.

[vincilbishop]

@vincilbishop does the save method work with this? I’ve tried this and still getting errors that save is undefined.

In the mockRepository object define a save: jest.fn as a sibling to metadata: and that should work. It was not a complete mock, just an example. You'll have to mock any methods you use. (as I mocked metaData:)

[woutrbe]

Ah alright, I somehow misunderstood this. Makes sense to define all the methods and mock them.

[lock[bot]]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.