test: replace function with arrow function

PR-URL: #17308 Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Vse Mozhet Byt <[email protected]> Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Daijiro Wachi <[email protected]> Reviewed-By: Gireesh Punathil <[email protected]> Reviewed-By: Jon Moss <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: karszawa

test/parallel/test-timers.js

@@ -54,12 +54,12 @@ const inputs = [
 consttimeouts=[];
 constintervals=[];
 
-inputs.forEach(function(value,index){
-setTimeout(function(){
+inputs.forEach((value,index)=>{
+setTimeout(()=>{
 timeouts[index]=true;
 },value);
 
-consthandle=setInterval(function(){
+consthandle=setInterval(()=>{
 clearInterval(handle);// disarm timer or we'll never finish
 intervals[index]=true;
 },value);
@@ -68,9 +68,9 @@ inputs.forEach(function(value, index){
 // All values in inputs array coerce to 1 ms. Therefore, they should all run
 // before a timer set here for 2 ms.
 
-setTimeout(common.mustCall(function(){
+setTimeout(common.mustCall(()=>{
 // assert that all other timers have run
-inputs.forEach(function(value,index){
+inputs.forEach((value,index)=>{
 assert(timeouts[index]);
 assert(intervals[index]);
 });