test: change callback function to arrow function

PR-URL: #17699
Reviewed-By: Yosuke Furukawa <yosuke.furukawa@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: skanamaru

test/parallel/test-http-date-header.js

@@ -5,7 +5,7 @@ const http = require('http');
 
 consttestResBody='other stuff!\n';
 
-constserver=http.createServer(function(req,res){
+constserver=http.createServer((req,res)=>{
 assert.ok(!('date'inreq.headers),
 'Request headers contained a Date.');
 res.writeHead(200,{
@@ -16,16 +16,16 @@ const server = http.createServer(function(req, res) {
 server.listen(0);
 
 
-server.addListener('listening',function(){
+server.addListener('listening',()=>{
 constoptions={
-port: this.address().port,
+port: server.address().port,
 path: '/',
 method: 'GET'
 };
-constreq=http.request(options,function(res){
+constreq=http.request(options,(res)=>{
 assert.ok('date'inres.headers,
 'Response headers didn\'t contain a Date.');
-res.addListener('end',function(){
+res.addListener('end',()=>{
 server.close();
 process.exit();
 });