Content
When testing a service that needs one parameter in the constructor, it's essential to initialize the service as a provider using an object instead of directly passing the service through:
auth.service.ts (example)
@Injectable()
export class AuthService {
constructor(
@InjectRepository(Admin)
private readonly adminRepository: Repository<Admin>,
) { }
// ...
}
auth.service.spec.ts (example)
describe('AuthService', () => {
let authService: AuthService
beforeEach(async () => {
const module = await Test.createTestingModule({
providers: [
AuthService,
{
provide: getRepositoryToken(Admin),
useValue: mockRepository,
},
],
}).compile()
authService = module.get<AuthService>(AuthService)
})
// ...
})
For more information on this topic, refer to this GitHub issue.
Current Challenge
In my case, the service requires two parameters in the constructor:
auth.service.ts
@Injectable()
export class AuthService {
constructor(
private readonly jwtService: JwtService,
private readonly authHelper: AuthHelper,
) {}
// ...
}
How do I initialize this service in the test environment? Since passing multiple values to useValue in the providers array is not straightforward, how can I handle this situation? The AuthService constructor expects two parameters, and both need to be provided for successful testing.
This is the current (non-working) setup:
auth.service.spec.ts
describe('AuthService', () => {
let service: AuthService
beforeEach(async () => {
const module: TestingModule = await Test.createTestingModule({
providers: [AuthService],
}).compile()
service = module.get<AuthService>(AuthService)
})
it('should be defined', () => {
expect(service).toBeDefined()
})
// ...
})
If the parameters are not passed, the following error occurs:
● AuthService › should be defined
Nest can't resolve dependencies of the AuthService (?, AuthHelper). Please ensure that the argument at index [0] is available in the TestModule context.