I have two files:

Simple Express app: app.js

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)
})

and an app.test.js

import axios from 'axios';

beforeAll( () => {
// Probably here I should start the server, but how?
});

test("test-my-api", async () => {
  const response = await axios.get("http://localhost:3000")
  expect(response.data).toBe("Hello World!")
}")

How can I run the app before testing the requests to the app in a secure manner? How is it done professionally?