test: add common.noop, default for common.mustCall()

Export a new common.noop no-operation function for general use.
Allow using common.mustCall() without a fn argument to simplify
test cases.

Replace various non-op functions throughout tests with common.noop

PR-URL: https://github.com/nodejs/node/pull/12027
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/test/parallel/test-net-listen-exclusive-random-ports.js b/test/parallel/test-net-listen-exclusive-random-ports.js
index 1909af067c..9ca023cfa4 100644
--- a/test/parallel/test-net-listen-exclusive-random-ports.js
+++ b/test/parallel/test-net-listen-exclusive-random-ports.js
@@ -1,11 +1,10 @@
 'use strict';
-require('../common');
+
+const common = require('../common');
 const assert = require('assert');
 const cluster = require('cluster');
 const net = require('net');
 
-function noop() {}
-
 if (cluster.isMaster) {
   const worker1 = cluster.fork();
 
@@ -21,7 +20,7 @@ if (cluster.isMaster) {
     });
   });
 } else {
-  const server = net.createServer(noop);
+  const server = net.createServer(common.noop);
 
   server.on('error', function(err) {
     process.send(err.code);