TwitchJS is what I use, it’s pretty much tmi.js but continued on with community support to keep it much more frequently updated.
Unfollowing and following again should still create a notification (it’s just the follow that will send a notification, the webhook intentionally doesn’t show unfollows), it’s what I did when first testing webhooks and it worked back then 
Another way to test would simply be point the followers topic to Ninja, if it’s working you’ll certainly know 