Is there any way to test this in debug mode?

[brspurri]

I'm just looking to test that this works, and don't want to push to Play to see it in action. Is there any way to test when running a debug version?

[androidmads]

You can test this with debug version.

Note:

if you have your application is in google play, then it works perfectly to intimate about newer version. if you are not uploaded any version of your application, then it gives update found result is false or provides error log as 404 response.

[brspurri]

Indeed, this does work in debug. Just a note for others testing, it appears the versionCode of your app must be lower than whats in the app store (I had originally thought versionName).