Testing add-on updates?

Updates to a new add-on version usually work seamless from the user’s point of view. Now I might get into a situation where I might have to add a new permission to the manifest. I understand that the user will then be warned about the new permission. Is this update process, including the warning, something I can test? I’d like to understand how exactly the warning looks like before I push out an update.

I’m talking about WebExtensions, BTW.

Create a WebExtension with a different ID. You can get a GUUID from here. After you create one then sign it as a unlisted extension by uploading it here.

In order to ship updates to your unlisted extension you need an update_url in your manifest.json. Example here. The releases page has older versions to see the updates working on my extension just to get an idea of how it should work.