googleads-mobile-plugins, test devices?

hi,

i'm using this package to show admob ads, and it works:
https://github.com/googleads/googleads-mobile-plugins

But how/where to define the test devices?

it has a boolean for "isTesting" when calling the ad, but it still counts the requests in admob stats:
public static void RequestBannerAd(bool isTesting)


Can I add test devices in some xml? (theres only the default AndroidManifest.xml in Plugins/Android/ folder.. looks different.)
http://stackoverflow.com/questions/...in-the-layout-xml-for-the-adv/9658040#9658040

Or have to edit java sources and compile? (seems like many topics indicate this..?)
https://code.google.com/p/google-mo.../AdMobPlugin.java?repo=admob-unity-plugin#158
https://developers.google.com/mobile-ads-sdk/docs/admob/additional-controls#play-test

Or maybe someone has modified version of it, so that you could pass test device id's directly from unity..?

*edit: this one seems to have easy test mode:
https://github.com/guillermocalvo/admob-unity-plugin