test: improve test-http-allow-req-after-204-res

* use const instead of var
* use common.mustCall to control functions execution
* use assert.strictEqual instead of assert.equal
* use arrow functions
PR-URL: #10503
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Prince John Wesley <princejohnwesley@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: edsadr

test/parallel/test-http-allow-req-after-204-res.js

@@ -1,45 +1,42 @@
 'use strict';
-require('../common');
-varhttp=require('http');
-varassert=require('assert');
+constcommon=require('../common');
+consthttp=require('http');
+constassert=require('assert');
 
 // first 204 or 304 works, subsequent anything fails
-varcodes=[204,200];
+constcodes=[204,200];
 
 // Methods don't really matter, but we put in something realistic.
-varmethods=['DELETE','DELETE'];
+constmethods=['DELETE','DELETE'];
 
-varserver=http.createServer(function(req,res){
-varcode=codes.shift();
-assert.equal('number',typeofcode);
+constserver=http.createServer(common.mustCall((req,res)=>{
+constcode=codes.shift();
+assert.strictEqual(typeofcode,'number');
 assert.ok(code>0);
-console.error('writing %d response',code);
 res.writeHead(code,{});
 res.end();
-});
+},codes.length));
 
 functionnextRequest(){
-varmethod=methods.shift();
-console.error('writing request: %s',method);
+constmethod=methods.shift();
 
-varrequest=http.request({
+constrequest=http.request({
 port: server.address().port,
 method: method,
 path: '/'
-},function(response){
-response.on('end',function(){
+},common.mustCall((response)=>{
+response.on('end',common.mustCall(()=>{
 if(methods.length===0){
-console.error('close server');
 server.close();
 }else{
 // throws error:
 nextRequest();
 // works just fine:
 //process.nextTick(nextRequest);
 }
-});
+}));
 response.resume();
-});
+}));
 request.end();
 }