test: refactor test-net-dns-error

- Use `common.mustCall()` and `common.mustNotCall()`.
- Use ternary operator.

PR-URL: #19640
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-net-dns-error.js

@@ -21,27 +21,20 @@
 
 'use strict';
 const common = require('../common');
-const assert = require('assert');
 
+const assert = require('assert');
 const net = require('net');
 
 const host = '*'.repeat(256);
+const errCode = common.isOpenBSD ? 'EAI_FAIL' : 'ENOTFOUND';
 
-let errCode = 'ENOTFOUND';
-if (common.isOpenBSD)
-  errCode = 'EAI_FAIL';
-
-function do_not_call() {
-  throw new Error('This function should not have been called.');
-}
-
-const socket = net.connect(42, host, do_not_call);
+const socket = net.connect(42, host, common.mustNotCall());
 socket.on('error', common.mustCall(function(err) {
   assert.strictEqual(err.code, errCode);
 }));
-socket.on('lookup', function(err, ip, type) {
+socket.on('lookup', common.mustCall(function(err, ip, type) {
   assert(err instanceof Error);
   assert.strictEqual(err.code, errCode);
   assert.strictEqual(ip, undefined);
   assert.strictEqual(type, undefined);
-});
+}));