For a long time, Firebase A/B Testing was an extension of Remote Config that allowed you to test different app configurations with different audiences and see which one worked best for your app.
A/B Testing can still do this, but it is no longer merely an extension, but now its own service. On top of the app configuration experiments we’ve always been able to do, we can now conduct Cloud Messaging Experiments by experimenting with sending messages to the right users at the right time for maximum user engagement.
The underlying process is very similar to the Remote Config Experiments. You define your experiment’s name, target users, then the variants by which messages reach which users. Then you set your goal and determine which metrics you want to track, then you can add your usual metadata that comes with cloud messages like custom data, expiry, and priority.
Really, the main goal of Cloud Messaging is re-engaging users back into your app when they’ve left it sitting silently in their app drawer, or keeping them engaged while they are using it. This A/B Test is all about finding the best way about doing that.