I always mess up by forgetting to comment out test data from my api's before I commit. So here is my solution.
This extension will automaticaly comment out anything for you when you stage your files.
Simple!
Add // Start Test on top of your test data and add // End Test at the end.
Done!
Now when you try to stage your files, anything between those two lines will be commented out.
Please do note currently this will only work for php files.