Before sending your notifications to users you can send a test notification to your own device only, this will allow you to test the actual notification in a real environment.
The first step is to add your device to the list of testers in OneSignal, access the “Audience” area in your OneSignal account and then click “All Users”:
You will need to find your own device in the list of users that is displayed, our suggestion is to close and re-open the app then look for your device based on the “Last Active” date, make sure to refresh the page to see your device at the top of the list. You can also refer to the Device model, Country and First Session parameters to identify your device.
Now click on “Options” and “Add to Test Users”:
Now when sending your notifications you will be able to use the “Send to Test Device” option, clicking on it will open a list of Test Users for you to select, and you can then send a test notification to yourself before sending it to all your users.