when you have a test version you will have a test url, so you can download the test version to your phone, via google play.
You can use the internal test channel for your testing.
when you open the app, if google play games works fine, you will se it popping up on the app start, regardless of your code. (Your code will not work btw)
A general tip: Try to understand how the events actually works, display things, hide them, make them visible, sub events, variables etc etc before you try to inlcude stuff like google play games! :)