test: change callback function to arrow function

PR-URL: #17697
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: routerman

test/parallel/test-http-default-encoding.js

@@ -6,11 +6,11 @@ const http = require('http');
 constexpected='This is a unicode text: سلام';
 letresult='';
 
-constserver=http.Server(function(req,res){
+constserver=http.Server((req,res)=>{
 req.setEncoding('utf8');
-req.on('data',function(chunk){
+req.on('data',(chunk)=>{
 result+=chunk;
-}).on('end',function(){
+}).on('end',()=>{
 server.close();
 res.writeHead(200);
 res.end('hello world\n');
@@ -23,15 +23,15 @@ server.listen(0, function() {
 port: this.address().port,
 path: '/',
 method: 'POST'
-},function(res){
+},(res)=>{
 console.log(res.statusCode);
 res.resume();
-}).on('error',function(e){
+}).on('error',(e)=>{
 console.log(e.message);
 process.exit(1);
 }).end(expected);
 });
 
-process.on('exit',function(){
+process.on('exit',()=>{
 assert.strictEqual(expected,result);
 });