You can test your app with in app purchase feature. you have to follow below steps for testing
- Upload you final signed apk file to Google play.
- Dont publish it
- Add in app products
- get in app products id and add to code
- get base 64 key and add to product
- sign apk and upload again
- your app should be in draft mode
- in you Google play account setting add your test account id
- use the device which should have the primary account id similar to the one you have added on Google play test account.
- Install signed apk you have uploaded to Google play to your device.
- run application and test your features