In order for your pre-production tests to be accurate, you need to ensure that your staging environment is set up correctly. To this end (and only if required), you need to make any necessary configuration changes to the environment, ready for your update to be put through its paces.
The method for this will vary depending on the setup of your server and staging environment, along with the configs that are required. In general, though, you'll want to create a backup of your production server, copy that backup, make your alterations, then update your test server with the altered backup.
Don't forget to restart the server after any changes are made!