test: use const/let and common.mustCall

remove process.on('exit') because all callbacks are
wrapped by common.mustCall.
PR-URL: #9959
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

Author: outsideris

test/parallel/test-tls-cnnic-whitelist.js

@@ -1,16 +1,15 @@
 'use strict';
-varcommon=require('../common');
-varassert=require('assert');
+constcommon=require('../common');
 
 if(!common.hasCrypto){
 common.skip('missing crypto');
 return;
 }
 
-vartls=require('tls');
-varfs=require('fs');
-varpath=require('path');
-varfinished=0;
+constassert=require('assert');
+consttls=require('tls');
+constfs=require('fs');
+constpath=require('path');
 
 functionfilenamePEM(n){
 returnpath.join(common.fixturesDir,'keys',n+'.pem');
@@ -20,7 +19,7 @@ function loadPEM(n) {
 returnfs.readFileSync(filenamePEM(n));
 }
 
-vartestCases=[
+consttestCases=[
 {// Test 0: for the check of a cert not existed in the whitelist.
 // agent7-cert.pem is issued by the fake CNNIC root CA so that its
 // hash is not listed in the whitelist.
@@ -58,27 +57,22 @@ var testCases = [
 ];
 
 functionrunTest(tindex){
-vartcase=testCases[tindex];
+consttcase=testCases[tindex];
 
 if(!tcase)return;
 
-varserver=tls.createServer(tcase.serverOpts,function(s){
+constserver=tls.createServer(tcase.serverOpts,(s)=>{
 s.resume();
-}).listen(0,function(){
+}).listen(0,common.mustCall(function(){
 tcase.clientOpts=this.address().port;
-varclient=tls.connect(tcase.clientOpts);
-client.on('error',function(e){
+constclient=tls.connect(tcase.clientOpts);
+client.on('error',common.mustCall((e)=>{
 assert.strictEqual(e.code,tcase.errorCode);
-server.close(function(){
-finished++;
+server.close(common.mustCall(()=>{
 runTest(tindex+1);
-});
-});
-});
+}));
+}));
+}));
 }
 
 runTest(0);
-
-process.on('exit',function(){
-assert.equal(finished,testCases.length);
-});