In-App Messaging allows you to communicate with your users while they are browsing the app, even if they did not accept push notifications. You can easily send a preview to your device before turning the campaign on for all your users.
To achieve that, Batch simulates the In-App display by sending you a push notification with your In-App message displayed as a landing page in your app. This will only allow you to see if your text and image are displayed properly.
In the in-app automation editor, click the ⚙️ to select your device in the saved devices, or copy your Installation ID in the corresponding field. Hit "Send test":
You will receive a push notification. Open it to see on your device a preview of the message you are editing.
If you don't see it right away, you should refer to the Mobile Landing debugging article: My Mobile Landing doesn't show.
💡 Note: Consider turning on the automation for a development version of your app if you want to test more than the aspect of your message (e.g. trigger, targeting, etc).