Getting "Nest can't resolve dependencies of the AuthService" running tests with Jest

Question

I'm new to Nest.js, and I've been working on tests for my AuthController, and I keep getting this error, why is that?

`Nest can't resolve dependencies of the AuthService (?, UserService, JwtService). "Please make sure that the argument UserModel at index [0] is available in the AuthModule context."

Potential solutions:
- Is AuthModule a valid NestJS module?
- If UserModel is a provider, is it part of the current AuthModule?
- If UserModel is exported from a separate @Module, is that module imported within AuthModule?
  @Module({
    imports: [ /* the Module containing UserModel */ ]
  })`

Here's the test module config for auth.controller.spec.ts:

const UserModel = getModelForClass(User);

describe('AuthController', () => {
  let app: INestApplication;
  let authService: AuthService;

  beforeEach(() => {
    jest.setTimeout(30000);
  });
  beforeAll(async () => {
    const module: TestingModule = await Test.createTestingModule({
      imports: [
        AuthModule,
        UserModule,
        MongooseModule.forRootAsync({
          useFactory: async () => {
            const mongo = await MongoMemoryServer.create();
            const uri = mongo.getUri();
            return {
              uri,
              useNewUrlParser: true,
              useUnifiedTopology: true,
            };
          },
        }),
      ],
      providers: [AuthService, UserService, JwtService, UserModel],
    }).compile();
    app = module.createNestApplication();
    app.useGlobalPipes(new ValidationPipe());
    await app.init();
    authService = module.get<AuthService>(AuthService);
  });

Here's the auth.module.ts file:

@Module({
  imports: [
    PassportModule,
    JwtModule.register({
      secret: process.env.JWT_SECRET_KEY,
      signOptions: { expiresIn: '30m' },
    }),
  ],
  controllers: [AuthController],
  providers: [AuthService, LocalStrategy, LocalAuthGuard, JwtAuthGuard],
  exports: [JwtAuthGuard],
})
export class AuthModule {}

And here's the UserModule:

const UserModel = getModelForClass(User);

@Module({
  imports: [
    MongooseModule.forFeature([
      {
        name: User.name,
        schema: UserSchema,
      },
    ]),
  ],
  providers: [UserService, UserModel],
  exports: [UserModel],
})
export class UserModule {}

Answer 1

The error message suggests that the AuthService has dependencies on UserModel, UserService, and JwtService, but Nest.js is unable to resolve these dependencies. This could be due to a few reasons:

• UserModel is not a valid provider: Make sure that UserModel is a valid provider in the current module or in a module that is imported by the current module. You can check if UserModel is a valid provider by checking if it is decorated with @Injectable().

• UserModel is not part of the current module: If UserModel is exported from a separate module, make sure that the module is imported by the current module. In this case, UserModel is exported from the UserModule, so make sure that UserModule is imported by the AuthModule.

• UserService and JwtService are not provided in the current module: Make sure that UserService and JwtService are provided in the current module or in a module that is imported by the current module. In this case, UserService and JwtService are not provided in the AuthModule, so you need to add them to the providers array in the AuthModule.

So, the solution is, AuthModule that includes UserService and JwtService in the providers array:

@Module({
  imports: [
    PassportModule,
    JwtModule.register({
      secret: process.env.JWT_SECRET_KEY,
      signOptions: { expiresIn: '30m' },
    }),
    UserModule, // make sure to import UserModule
  ],
  controllers: [AuthController],
  providers: [AuthService, LocalStrategy, LocalAuthGuard, JwtAuthGuard, UserService, JwtService],
  exports: [JwtAuthGuard],
})
export class AuthModule {}

Thank you.