I would like to know what best practices should I do for testing the functionality when a user buy an item/power-ups via Google Play and purchased with real money?
For example, basically, creating a simple test of purchasing and saving an item stored in the inventory during the game using a game money. (e.g. Gil from Final Fantasy series or Zenny from Tron Bonne for the PlayStation 1) I know how to make money purchase update only via game money when I'm programming in Unity3D or Eclipse w/ LibGDX library.
Now, let say I have to create a program that checks the user if actually purchase a power-up items using real money. Next, the system needs to check for online status. If connected, it will simply go to the Google Play dialog and asks the user if he/she wanted to proceed purchasing of items. If yes and the credit card balance is sufficient, then goes back to the game app and check if the boolean returns true, then item that the user is bought will be saved.
Another example is that the amount of real money will be calculated via programming and if insufficient, the user asks to add more real money value by purchasing it via Google Play. If return true, then, the real money value will be reloaded.
This concept is basically needed for game developers. However, is there a safe way to test the real money purchase test stuff without using a credit card value or something before the actual publishing of the game app in Google Play along with this feature? Is there a tutorial, start-up guide, recommendation or something for this? Please, I would like to know how will I start. Thank you.