Hello everyone, I want to add my device as a test device to test mediation. I tried to add the test device through AdMob UI: https://support.google.com/admob/answer/9691433 but I never got any test ads on my device. Every time I got error 3 which is Ad failed to load.
Other way is to add this line below as mentioned on this link: https://developers.google.com/admob/android/test-ads
But I am not understanding where should I add this line? In which file should I add this line?
Thanks for your help.