fix for mongoose connect / disconnect using Jest

solution.js

require('dotenv').config();
const mongoose = require('mongoose');

const { MONGO_URI, MONGO_DB } = process.env;
const mongo_db = mongoose.createConnection(`${MONGO_URI}${MONGO_DB}`); // moved to global space

describe('User.formSubmit() Mutation', () => {
  let user;
  beforeAll(async (done) => {
    user = await models.User.create(userMock());
    done();
  });

  afterAll(async (done) => {
    await user.destroy();
    await models.sequelize.close();
    done();
  });

  test('suite setup ready', () => {
    expect(user).toBeDefined();
  });
});

mongo_db.close(); // close at end of script