test: refactor test for net listen on fd0

Replace var to const/let, use common.mustCall on callbacks and move process.on('exit') to the .on('error') handler PR-URL: #10025 Reviewed-By: Santiago Gimeno <[email protected]> Reviewed-By: Gibson Fahnestock <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: julianduque

test/parallel/test-net-listen-fd0.js

@@ -1,20 +1,12 @@
 'use strict';
-varcommon=require('../common');
-varassert=require('assert');
-varnet=require('net');
+constcommon=require('../common');
+constassert=require('assert');
+constnet=require('net');
 
-vargotError=false;
-
-process.on('exit',function(){
-assert(gotErrorinstanceofError);
-});
-
-// this should fail with an async EINVAL error, not throw an exception
-net.createServer(common.fail).listen({fd: 0}).on('error',function(e){
-switch(e.code){
-case'EINVAL':
-case'ENOTSOCK':
-gotError=e;
-break;
-}
-});
+// This should fail with an async EINVAL error, not throw an exception
+net.createServer(common.fail)
+.listen({fd: 0})
+.on('error',common.mustCall(function(e){
+assert(einstanceofError);
+assert(['EINVAL','ENOTSOCK'].includes(e.code));
+}));