How do I test messages before sending them to my subscribers?
Please let me draw your attention to the Test Device feature. Using this feature you can send push notification only to devices assigned as Test in order to check how the notification looks like.
You can find a detailed guide about how to add a test device by following the link below.
After you have added your test device, you can use "Test Woosh" button in the Send Push form, and the notification will be sent only to registered test devices.