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Testing custom repositories (NestJS/TypeORM)

Published September 5, 2021Last updated February 4, 20242 min read

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 });
});
});
});

Integration testing

Integration testing is more suitable when working with databases. Read more about it on Integration testing Node.js apps post

Boilerplate

Here is the link to the boilerplate I use for the development. It contains the examples mentioned above with more details.