At GitHub we use a staging environment called review-lab for testing with production data. Deploying a branch to review-lab for testing is one of the best ways to test your work with real production data prior to an actual production deployment.
To make testing on review-lab for extended periods of time easier, you can use the Redirector extension for Chrome to redirect all GitHub.com traffic to your review-lab deploy URL.
https:\/\/github\.com\/?(.+)?
https://branchname.review-lab.github.com/$1
where branchname
is the name of your branch.