Checkpoints are used to provide insight regarding the way your testers use your apps.
These can help you monitor when a tester has reached key points in your app, such as or visiting the in-app store.
A checkpoint is a string written to log with the tag testfairy-checkpoint.

Syntax

To add a checkpoint called "Purchase ok" please add the following line

Log.v("testfairy-checkpoint", "Purchase OK");

By adding the line above, a new column in your build coverage page will appear. It will be titled "Purchase OK", and will be turned only for sessions where this log appears.
There is no SDK to integrate. You can safely submit apps containing checkpoints information to the Store. Please remember that logs are visible to all with via adb, so consider the names of your checkpoints.

Code example

public class MyActivity extends Activity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
                Log.v("testfairy-checkpoint", "Purchase OK");
        }
}

Consider the following flow: your tester has started the app, and visited the store in your app. You would like to track which sessions completed a successful purchase.

Screenshot without