Create const for secure event

lib/agent/socket_util.js

@@ -18,6 +18,8 @@ const ocspFailOpenWarning =
   'without OCSP based Certificated Revocation checking as it could not obtain a valid OCSP Response to use from ' +
   'the CA OCSP responder. Details: ';
 
+const socketSecuredEvent = 'secureConnect';
+
 const rawOcspFlag =
   process.env.SF_OCSP_RESPONSE_CACHE_SERVER_ENABLED;
 
@@ -72,7 +74,7 @@ exports.secureSocket = function (socket, host, agent, mock)
   const validate = function ()
   {
     // stop listening for the secure event
-    socket.removeListener('secureConnect', validate);
+    socket.removeListener(socketSecuredEvent, validate);
 
     Logger.getInstance().trace('socket reused = %s', socket.isSessionReused());
 
@@ -112,7 +114,7 @@ exports.secureSocket = function (socket, host, agent, mock)
   };
 
   // when the socket is secure, perform additional validation
-  socket.on('secureConnect', validate);
+  socket.on(socketSecuredEvent, validate);
 
   // block all writes until validation is complete
   socket.cork();