Posted on Jan 23, 2023 • Originally published at sevic.dev on Jan 23, 2023

Testing custom repositories (NestJS/TypeORM)

Custom repositories extend the base repository class and enrich it with several additional methods. This post covers the unit and integration testing.

// user.repository.ts @Injectable() export class UserRepository extends Repository<UserEntity> { constructor(private dataSource: DataSource) { super(UserEntity, dataSource.createEntityManager()); } async getById(id: string) { return this.findOne({ where: { id } }); } // ... }

Setup

Inject a custom repository into the service.

// user.service.ts export class UserService { constructor(private readonly userRepository: UserRepository) {} async getById(id: string): Promise<User> { return this.userRepository.getById(id); } // ... }

Pass entity class to the forFeature method.

// user.module.ts @Module({ imports: [ TypeOrmModule.forFeature([UserEntity])], // ... ], providers: [UserService, UserRepository], // ... }) export class UserModule {}

Unit testing

To properly unit-test the custom repository, mock some methods.

// user.repository.spec.ts describe('UserRepository', () => { let userRepository: UserRepository; const dataSource = { createEntityManager: jest.fn() }; beforeEach(async () => { const module: TestingModule = await Test.createTestingModule({ providers: [ UserRepository, { provide: DataSource, useValue: dataSource } ] }).compile(); userRepository = module.get<UserRepository>(UserRepository); }); describe('getById', () => { it('should return found user', async () => { const id = 'id'; const user = { id }; const findOneSpy = jest .spyOn(userRepository, 'findOne') .mockResolvedValue(user as UserEntity); const foundUser = await userRepository.getById(id); expect(foundUser).toEqual(user); expect(findOneSpy).toHaveBeenCalledWith({ where: user }); }); }); });