Nest.js: initialization of property from controller's superclass

Question

I have a question regarding unit testing controllers in Nest.js framework. Problem is that property from a superclass is not initialized in the controller class when creating a test module.

This is a sample code I'm talking about:

export class MyController extends SomeOtherController {

    // Inherited from SomeOtherController
    async initSomeObject() {
        this.someObject = await initializeThisSomehow();
    }

    async controllerMethod(args: string) {
        // Do something
    }

}

export abstract class SomeOtherController implements OnModuleInit {

    protected someObject: SomeObject;

    async onModuleInit() {
        await this.initSomeObject();
    }

    abstract async initSomeObject(): Promise<void>;
}

And this is how I've created my test

describe('MyController', () => {
  let module: TestingModule;
  let controller: MyController;
  let service: MyService;

  beforeEach(async () => {
    module = await Test.createTestingModule({
      imports: [],
      controllers: [MyController],
      providers: [
        MyService,
        {
          provide: MyService,
          useFactory: () => ({
            controllerMethod: jest.fn(() => Promise.resolve()),
          }),
        },
      ],
    }).compile();

    controller = module.get(MyController);
    service = module.get(MyService);
  });

  describe('controller method', () => {
    it('should do something', async () => {
      jest.spyOn(service, 'controllerMethod').mockImplementation(async _ => mockResult);
      expect(await controller.controllerMethod(mockArgs)).toBe(mockResult);
    });
  });
});

Now, if I were to run the application in development mode, the someObject property would get initialized, and code works. But when running tests, it seems like the test module is not initializing it (so it is undefined).

Any sort of help is much appreciated.

Answer 1

In your test's before each you need to run the following

await module.init(); // this is where onModuleInit is called

It's also best to close the application

afterEach(async () => await module.close());