replace get-port with OS default port in ip_extractor.spec.js (#6095)

Author: simon-id

packages/dd-trace/test/plugins/util/ip_extractor.spec.js

@@ -2,28 +2,24 @@
 
 require('../../setup/tap')
 
-const getPort = require('get-port')
 const { extractIp } = require('../../../src/plugins/util/ip_extractor')
 const http = require('http')
 const axios = require('axios')
 
 describe('ip extractor', () => {
   let port, appListener, controller
 
-  before(() => {
-    return getPort().then(newPort => {
-      port = newPort
-    })
-  })
-
   before(done => {
     const server = new http.Server(async (req, res) => {
       controller && await controller(req, res)
       res.writeHead(200)
       res.end(JSON.stringify({ message: 'OK' }))
     })
     appListener = server
-      .listen(port, 'localhost', () => done())
+      .listen(0, 'localhost', () => {
+        port = server.address().port
+        done()
+      })
   })
 
   after(() => {