test: improve test-net-socket-timeout

* Check for custom Node.js code rather than constructor in
  assert.throws().
* Use arrow functions consistently.

PR-URL: #24859
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

test/parallel/test-net-socket-timeout.js

@@ -34,25 +34,25 @@ const validDelays = [0, 0.001, 1, 1e6];
 
 
 for (let i = 0; i < nonNumericDelays.length; i++) {
-  assert.throws(function() {
+  assert.throws(() => {
     s.setTimeout(nonNumericDelays[i], () => {});
-  }, TypeError, nonNumericDelays[i]);
+  }, { code: 'ERR_INVALID_ARG_TYPE' }, nonNumericDelays[i]);
 }
 
 for (let i = 0; i < badRangeDelays.length; i++) {
-  assert.throws(function() {
+  assert.throws(() => {
     s.setTimeout(badRangeDelays[i], () => {});
-  }, RangeError, badRangeDelays[i]);
+  }, { code: 'ERR_OUT_OF_RANGE' }, badRangeDelays[i]);
 }
 
 for (let i = 0; i < validDelays.length; i++) {
   s.setTimeout(validDelays[i], () => {});
 }
 
 const server = net.Server();
-server.listen(0, common.mustCall(function() {
-  const socket = net.createConnection(this.address().port);
-  socket.setTimeout(1, common.mustCall(function() {
+server.listen(0, common.mustCall(() => {
+  const socket = net.createConnection(server.address().port);
+  socket.setTimeout(1, common.mustCall(() => {
     socket.destroy();
     server.close();
   }));