Hello Ann,
You can find a lot of really helpful information here:
http://developer.android.com/guide/topics/testing/testing_android.html
I think res folder is optional, it is present and has layour/drawable/values empty folder, since your test application is depend
on testing application, it is using testing application's res folder to get R class and whatever info it needs. So your test
should have empty res folders as well as gen folders. Because test apk is using all resources from main apk.
Test is not allowed to change layout. It is not logical.
Your test, when you run it, will trigger main app and test app rebuilding, otherwise you will not see any changes in your test
logic, because it will be not deployed on device.
Please let me know if you have any questions.
Best regards,
Robotium fan, Yahor