wrap server.listen in if module

prevents server from starting durring testing/scripting

server/server.js

@@ -301,20 +301,15 @@ if (true) { // eslint-disable-line
   });
 }
 
-/**
- * Start Express server.
- */
+module.exports = app;
 
-
-app.listen(app.get('port'), function() {
+// start the server if `$ node server.js`
+if (require.main === module) {
+  app.listen(app.get('port'), function() {
     console.log(
       'FreeCodeCamp server listening on port %d in %s mode',
       app.get('port'),
       app.get('env')
     );
-});
-
-// start the server if `$ node server.js`
-
-
-module.exports = app;
+  });
+}