如何重构我的ExpressJS + Sequelize文件，以便正确使用Jest？

// models/index.js
const fs = require('fs');
const path = require('path');
const Sequelize = require('sequelize');
const config = require('../config/database.js');

const sequelize = new Sequelize(config.database, config.username, config.password, config);

const models = {};

fs.readdirSync(__dirname)
  .filter(file => (file.indexOf('.') !== 0) && (file !== 'index.js'))
  .forEach(file => {
    const model = sequelize.import(path.join(__dirname, file));
    models[model.name] = model;
  });

Object.keys(models).forEach(modelName => {
  if (models[modelName].associate) {
    models[modelName].associate(models);
  }
});

module.exports = {
  sequelize,
  models,
};

// models/user.js
module.exports = (sequelize, DataTypes) => {
  const User = sequelize.define('User', {
    name: DataTypes.STRING,
    email: DataTypes.STRING,
    password: DataTypes.STRING,
  }, {});

  User.associate = function(models) {
    User.hasMany(models.Post);
  };

  return User;
};

// config/database.js
module.exports = {
  database: 'your_database_name',
  username: 'your_database_username',
  password: 'your_database_password',
  host: 'your_database_host',
  dialect: 'your_database_dialect',
};

// __tests__/routes/users.test.js
const request = require('supertest');
const app = require('../app');

describe('GET /users', () => {
  it('should return a list of users', async () => {
    const response = await request(app).get('/users');
    expect(response.statusCode).toBe(200);
    expect(response.body).toHaveLength(2);
  });
});