Play Store Beta Testing, Android Keystore, and Hired Developer

So I have several "issues".

I hired a developer for my apps, and he needs live access Play Store Alpha / Beta testing. We are testing In-App purchasing, and it cannot be tested on device.

I granted him permission (from dev console) to access Alpha/Beta sections. One thing I don't want to give him is my Keystore / Signing key, along with my password.

Play Store wants APK signed with original key for Beta testing (or do they?)

So how do I go about it?

And another question - how do teams with multiple devs deal with these issues?

If you don't want to give him the keys you have these options:

1. You need to build and sign every single apk he wants to upload to google play.
2. Set up a build server like jenkins and let jenkins build + sign on every git push. Then make the resulting signed apk available to the team.
3. Create some internal signing service where developers can submit an apk file and get it back signed.