test: avoid assigning this to variables

This commit removes assignments of this to a variable in the
tests.
PR-URL: #10548
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: cjihrig

test/parallel/test-cluster-worker-wait-server-close.js

@@ -32,12 +32,12 @@ if (cluster.isWorker) {
 // start worker
 varworker=cluster.fork();
 
-varsocket;
 // Disconnect worker when it is ready
 worker.once('listening',function(){
-net.createConnection(common.PORT,common.localhostIPv4,function(){
-socket=this;
-this.on('data',function(){
+constsocket=net.createConnection(common.PORT,common.localhostIPv4);
+
+socket.on('connect',function(){
+socket.on('data',function(){
 console.log('got data from client');
 // socket definitely connected to worker if we got data
 worker.disconnect();

test/parallel/test-http-client-timeout-agent.js

@@ -50,9 +50,8 @@ server.listen(0, options.host, function() {
 this.destroy();
 });
 req.setTimeout(50,function(){
-varreq=this;
 console.log('req#'+this.id+' timeout');
-req.abort();
+this.abort();
 requests_done+=1;
 });
 req.end();

test/parallel/test-repl-persistent-history.js

@@ -21,26 +21,24 @@ os.homedir = function() {
 classActionStreamextendsstream.Stream{
 run(data){
 const_iter=data[Symbol.iterator]();
-constself=this;
-
-functiondoAction(){
+constdoAction=()=>{
 constnext=_iter.next();
 if(next.done){
 // Close the repl. Note that it must have a clean prompt to do so.
-setImmediate(function(){
-self.emit('keypress','',{ctrl: true,name: 'd'});
+setImmediate(()=>{
+this.emit('keypress','',{ctrl: true,name: 'd'});
 });
 return;
 }
 constaction=next.value;
 
 if(typeofaction==='object'){
-self.emit('keypress','',action);
+this.emit('keypress','',action);
 }else{
-self.emit('data',action+'\n');
+this.emit('data',action+'\n');
 }
 setImmediate(doAction);
-}
+};
 setImmediate(doAction);
 }
 resume(){}

test/parallel/test-zlib.js

@@ -102,24 +102,24 @@ SlowStream.prototype.pause = function() {
 };
 
 SlowStream.prototype.resume=function(){
-varself=this;
-if(self.ended)return;
-self.emit('resume');
-if(!self.chunk)return;
-self.paused=false;
-emit();
-functionemit(){
-if(self.paused)return;
-if(self.offset>=self.length){
-self.ended=true;
-returnself.emit('end');
+constemit=()=>{
+if(this.paused)return;
+if(this.offset>=this.length){
+this.ended=true;
+returnthis.emit('end');
 }
-varend=Math.min(self.offset+self.trickle,self.length);
-varc=self.chunk.slice(self.offset,end);
-self.offset+=c.length;
-self.emit('data',c);
+varend=Math.min(this.offset+this.trickle,this.length);
+varc=this.chunk.slice(this.offset,end);
+this.offset+=c.length;
+this.emit('data',c);
 process.nextTick(emit);
-}
+};
+
+if(this.ended)return;
+this.emit('resume');
+if(!this.chunk)return;
+this.paused=false;
+emit();
 };
 
 SlowStream.prototype.end=function(chunk){