As you prepare to set your app live, there are some universal best practices for testing your app.
Ensure your app looks & functions how you expect, and in the best way possible for your users!
Your app has a unique set of code, and therefore quirks in behavior and the occasional bug sometimes crop up. Whether this is your first ever app submission or it's your 8th update this week, it's vital that you test your app before hitting the "Submit" button.
What to Test
Short answer: everything! Run through all of the expected behaviors of your end users. Simulate reading an article with ads. Watch a full video. Check all of your banners are viewable in the carousel. Log in as a user. Sign up as a new user. If your app is already live, test what's unique to your app and what's new in this version. You get the idea!
Here's a quick checklist for efficient app testing.
In-app purchases and subscriptions
3rd party user authentication (Database Integration)
Ads (Article and Video)
Branding and logos
UI Design (colors, icons, images)
Test all functionality across devices (don't forget tablets!) and platforms.