Play Store Sandbox Testing

Create a test user on Google Play Console

1. On Google Play Console click on Settings annd select License testing
2. Add the testers accounts you want to enable testing
3. Select a response: RESPOND_NORMALLY allow to test normal subscription and in app flow.

Test on Android Emulator

You could test on Android Emulator but Google recommends using a real device. If you test on an Emulator, use a version with Google Play Services installed.