test: update test-cluster-worker-events to use arrow functions

PR-URL: #23469
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-cluster-worker-events.js

@@ -30,7 +30,7 @@ if (cluster.isMaster) {
 
   const worker = cluster.fork();
 
-  worker.on('exit', function(code) {
+  worker.on('exit', (code) => {
     assert.strictEqual(code, OK);
     process.exit(0);
   });
@@ -49,31 +49,31 @@ assert(cluster.isWorker);
 let sawProcess;
 let sawWorker;
 
-process.on('message', function(m) {
-  assert(!sawProcess);
-  sawProcess = true;
-  check(m);
-});
-
-cluster.worker.on('message', function(m) {
-  assert(!sawWorker);
-  sawWorker = true;
-  check(m);
-});
-
 const messages = [];
 
-function check(m) {
+const check = (m) => {
   messages.push(m);
 
   if (messages.length < 2) return;
 
   assert.deepStrictEqual(messages[0], messages[1]);
 
-  cluster.worker.once('error', function(e) {
+  cluster.worker.once('error', (e) => {
     assert.strictEqual(e, 'HI');
     process.exit(OK);
   });
 
   process.emit('error', 'HI');
-}
+};
+
+process.on('message', (m) => {
+  assert(!sawProcess);
+  sawProcess = true;
+  check(m);
+});
+
+cluster.worker.on('message', (m) => {
+  assert(!sawWorker);
+  sawWorker = true;
+  check(m);
+});