Repository: fastify/fastify
File: test/close-pipelining.test.js (JavaScript)

Code before:
  fastify.get('/', async (req, reply) => {
    fastify.close()
    return { hello: 'world' }
  })

  await fastify.listen({ port: 0 })

  const instance = new Client('http://localhost:' + fastify.server.address().port, {
    pipelining: 2
  })

  const codes = [200, 200, 503]
  const responses = await Promise.all([
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' })
  ])
  const actual = responses.map(r => r.statusCode)

  t.same(actual, codes)

  await instance.close()
})

const isNodeVersionGte19 = semver.gte(process.version, '19.0.0')
test('Should close the socket abruptly - pipelining - return503OnClosing: false, skip Node < v19', { skip: !isNodeVersionGte19 }, async t => {
  // Since Node v20, we will always invoke server.closeIdleConnections()
  // therefore our socket will be closed
  const fastify = Fastify({
    return503OnClosing: false,
    forceCloseConnections: false
  })

  fastify.get('/', async (req, reply) => {
    reply.send({ hello: 'world' })
    fastify.close()
  })

  await fastify.listen({ port: 0 })

  const instance = new Client('http://localhost:' + fastify.server.address().port, {
    pipelining: 2
  })

  const responses = await Promise.allSettled([
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' })
  ])


Review comment (suggestion):
```suggestion
test('Should close the socket abruptly - pipelining - return503OnClosing: false', async t => {
```

You can remove the `skip` condition as we do not plan to support `node@18` in `fastify@5`.

Code after:
    fastify.close()
    return { hello: 'world' }
  })

  await fastify.listen({ port: 0 })

  const instance = new Client('http://localhost:' + fastify.server.address().port, {
    pipelining: 2
  })

  const codes = [200, 200, 503]
  const responses = await Promise.all([
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' })
  ])
  const actual = responses.map(r => r.statusCode)

  t.same(actual, codes)

  await instance.close()
})

test('Should close the socket abruptly - pipelining - return503OnClosing: false', async t => {
  // Since Node v20, we will always invoke server.closeIdleConnections()
  // therefore our socket will be closed
  const fastify = Fastify({
    return503OnClosing: false,
    forceCloseConnections: false
  })

  fastify.get('/', async (req, reply) => {
    reply.send({ hello: 'world' })
    fastify.close()
  })

  await fastify.listen({ port: 0 })

  const instance = new Client('http://localhost:' + fastify.server.address().port, {
    pipelining: 2
  })

  const responses = await Promise.allSettled([
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' }),
    instance.request({ path: '/', method: 'GET' })
  ])

  t.equal(responses[0].status, 'fulfilled')
  t.equal(responses[1].status, 'fulfilled')