I'm afraid there is no support for test accounts. Please check out this post as this has been discussed already:
Hi,
I've written an app for Windows Store that displays today's, yesterday's, this and last months adsense income, cpc, rpm, ctr, clicks and page views.
However in order for the Windows Store team to certificate the app, they need to login to the app. I only have my personal AdSense account (which contains my life, not planing to giveout it's password), and switching the test server is not acceptable with a setting or so (they don't allow it). Therefore I need a working readonly adsense account.
What shall I do?
Technical details:
I'm not using any libraries as it will be a WinRT app, I'm calling API endpoints such as:
Thanks,
Sinan