test: simplify test-tls-ecdh-auto

Avoid the process 'exit' event handler and use execFile instead of
manual stream operations.
Refs: #46751
PR-URL: #46911
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>

Author: tniessen

test/parallel/test-tls-ecdh-auto.js

@@ -12,7 +12,7 @@ if (!common.opensslCli)
 
 constassert=require('assert');
 consttls=require('tls');
-constspawn=require('child_process').spawn;
+const{ execFile }=require('child_process');
 constfixtures=require('../common/fixtures');
 
 functionloadPEM(n){
@@ -29,33 +29,15 @@ const options = {
 
 constreply='I AM THE WALRUS';// Something recognizable
 
-constserver=tls.createServer(options,function(conn){
+constserver=tls.createServer(options,(conn)=>{
 conn.end(reply);
-});
-
-letgotReply=false;
-
-server.listen(0,function(){
+}).listen(0,common.mustCall(()=>{
 constargs=['s_client',
 '-cipher',`${options.ciphers}`,
-'-connect',`127.0.0.1:${this.address().port}`];
-
-constclient=spawn(common.opensslCli,args);
+'-connect',`127.0.0.1:${server.address().port}`];
 
-client.stdout.on('data',function(data){
-constmessage=data.toString();
-if(message.includes(reply))
-gotReply=true;
-});
-
-client.on('exit',function(code){
-assert.strictEqual(code,0);
+execFile(common.opensslCli,args,common.mustSucceed((stdout)=>{
+assert(stdout.includes(reply));
 server.close();
-});
-
-client.on('error',assert.ifError);
-});
-
-process.on('exit',function(){
-assert.ok(gotReply);
-});
+}));
+}));