old_contents: 
  const request = require('supertest');
  const app = require('../../src/app');
  
  beforeAll((done) => {
    app.on('ready', () => {
      done();
    });
  });
  
  //------------------------------------------------------------
  //                     404 Test
  //------------------------------------------------------------
  
  test('It should return 404 error', () => {
    return request(app).get('/v1').then((response) => {
      expect(response.statusCode).toBe(404);
    });
  });
  
new_contents: 
  const request = require('supertest');
  const app = require('../../src/app');
  
  beforeAll((done) => {
    app.on('ready', () => {
      done();
    });
  });
  
  //------------------------------------------------------------
  //                     404 Test
  //------------------------------------------------------------
  
  test('It should return 404 error', async () => {
    const response = await request(app).get('/v1');
    expect(response.statusCode).toBe(404);
  });
  
subject: update error test with async