test: replace string concatenation with path.join

PR-URL: #14272 Reviewed-By: Rich Trott <[email protected]> Reviewed-By: Gibson Fahnestock <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Tobias Nießen <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Gireesh Punathil <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Trevor Norris <[email protected]>

Author: jkzing

test/async-hooks/test-graph.tls-write.js

@@ -11,6 +11,7 @@ const initHooks = require('./init-hooks');
 constverifyGraph=require('./verify-graph');
 constfs=require('fs');
 consttls=require('tls');
+constpath=require('path');
 
 consthooks=initHooks();
 hooks.enable();
@@ -20,8 +21,8 @@ hooks.enable();
 //
 constserver=tls
 .createServer({
-cert: fs.readFileSync(common.fixturesDir+'/test_cert.pem'),
-key: fs.readFileSync(common.fixturesDir+'/test_key.pem')
+cert: fs.readFileSync(path.join(common.fixturesDir,'test_cert.pem')),
+key: fs.readFileSync(path.join(common.fixturesDir,'test_key.pem'))
 })
 .on('listening',common.mustCall(onlistening))
 .on('secureConnection',common.mustCall(onsecureConnection))