在测试应用程序中，使用AdonisJS数据库提供程序中的migrations和seeds来创建和填充测试数据库。

以下是示例代码：

1. 创建测试用DatabaseProvider.js，导出在测试期间使用的不同数据库连接。

const { ServiceProvider } = require('@adonisjs/fold')

class DatabaseProvider extends ServiceProvider {
  register () {
    this.app.singleton('Database/Connection:test', () => {
      const Config = this.app.use('Adonis/Src/Config')
      const Database = require('@adonisjs/lucid/src/Database')
      const db = new Database()
      db.connect(Config.get('database.connections.test'))
      return db.connection()
    })
  }
}

module.exports = DatabaseProvider

2. 填充测试数据库的种子文件中，使用测试数据库的连接字符串。

'use strict'

/*
|--------------------------------------------------------------------------
| Blog Posts Seeder
|--------------------------------------------------------------------------
|
| Make use of Lucid ORM factory to seed database with dummy data.
|
*/

const Factory = use('Factory')
const Database = use('Database')

class BlogPostSeeder {
  async run () {
    const db = await Database.connect('test')

    await db.truncate('blog_posts')

    await Factory.model('App/Models/BlogPost').createMany(10)
  }
}

module.exports = BlogPostSeeder

3. 在测试文件中引入DatabaseProvider.js和需要测试的模型

'use strict'

const { test, trait } = use('Test/Suite')('User Account')

trait('Test/ApiClient')
trait('Auth/Client')

const Database = use('Database')
const User = use('App/Models/User')

const USER_PAYLOAD = {
  username: 'user',
  email: 'user@testing.com',
  password: 'password'
}

test('Successful account creation', async ({ client }) => {
  await use('DatabaseProvider')

  // Ensure that the test database is selected
  await Database.connect('test')

  const response = await client.post('/api/v1/auth/register')
    .send(USER_PAYLOAD)
    .end()

  response.assertStatus(201)

  // Ensure that the user was created in the test database
  const user = await User.findBy('email', USER_PAYLOAD.email)
  assert.equal(user.email, USER_PAYLOAD.email)
})