Test express API with jest

I'm currently learning how to create API with typescript and i'm trying to test API using jest framework. I know that using it with basic express application like

app = express()

supertest(app)

works fine. But i have a custom App class which throws errors when trying to do the same to it.(API without tests works fine). Is there a way to test it with jest?

api.test.ts

import { app } from '../../src/index';
import supertest from 'supertest';

describe('/users', () => {
it('Should return: 401 Unauthorized', async () => {
    await supertest(app).get('/api/users').expect(401, {
        status: 401,
         message: 'Unauthorized',
      });
   });
});

app.ts

class App {
public express: Application;
public port: number;

constructor(controllers: Controller[], port: number) {
    this.express = express();
    this.port = port;
    this.initializeDatabaseConnection();
    this.initializeMiddleware();
    this.initializeControllers(controllers);
    this.initializeErrorHandling();
}

private initializeDatabaseConnection(): void {
    const { MONGO_URI } = process.env;
    mongoose.connect(`${MONGO_URI}`);
}

private initializeMiddleware(): void {
    this.express.use(helmet());
    this.express.use(cors());
    this.express.use(morgan('dev'));
    this.express.use(express.urlencoded({ extended: false }));
    this.express.use(express.json());
    this.express.use(compression());
}

private initializeControllers(controllers: Controller[]): void {
    controllers.forEach((controller: Controller) => {
        this.express.use('/api', controller.router);
    });
}

private initializeErrorHandling(): void {
    this.express.use(ErrorHandler);
}

public listen(): void {
    this.express.listen(this.port, () => {
        console.log(`App is running on port ${this.port}`);
    });
}
}

export default App;

index.ts

import FlightController from './resources/flight/flight.controller';
import 'dotenv/config';
import App from './app';
import validateEnv from './utils/validateEnv';
import UserController from './resources/user/user.controller';

validateEnv();

export const app = new App(
    [new FlightController(), new UserController()],
    Number(process.env.PORT)
);

app.listen();

ERROR

  ●  Cannot log after tests are done. Did you forget to wait for something async in your test?
    Attempted to log "App is running on port 3000".

      42 |
      43 |     private initializeErrorHandling(): void {
    > 44 |         this.express.use(ErrorHandler);
         |                     ^
      45 |     }
      46 |
      47 |     public listen(): void {

      at console.log (node_modules/@jest/console/build/CustomConsole.js:172:10)
      at Server.<anonymous> (src/app.ts:44:21)



FAIL  __tests__/e2e/flight.api.test.ts
  /users                                                                                                                        
    × should return 200 and user info (2 ms)                                                                                    
                                                                                                                                
  ● /users › should return 200 and user info                                                                                    
                                                                                                                                
    TypeError: app.address is not a function

      4 | describe('/users', () => {
      5 |     it('should return 200 and user info', async () => {
    > 6 |         await request(app).get('/api/users').expect(401, {
        |                            ^
      7 |             status: 401,
      8 |             message: 'Unauthorized',
      9 |         });