[Backend] (Nest.js) Explore using ModuleRef to avoid re-declaring providers and controllers in tests

[prestonlimlianjie]

As proposed by @lamkeewei in #823 (comment)

Currently, we have to define the Sequelize model in the Module declaration with two different ways - following the Nest.js docs. It could get confusing because it's not entirely clear why they need to be defined as such.

Application code

// auth.module.ts

@Module({
  imports: [ConfigModule, SequelizeModule.forFeature([User])],
  controllers: [AuthController],
  providers: [AuthService],
})

Test code

// auth.controller.spec.ts
const module: TestingModule = await Test.createTestingModule({
      imports: [ConfigModule],
      controllers: [AuthController],
      providers: [
        AuthService,
        {
          provide: getModelToken(User),
          useValue: mockModel,
        },
      ],
    }).compile()

Solution

Explore using ModuleRef in more detail