Notification tasks are little bit tricky. Notifications are triggered by system when the requirements are fulfilled. (like finish a course, expire a certificate, reset password, finish assessment, etc.)

Here is a typical task:
https://rippleops.atlassian.net/browse/SUCO-601

Notifications triggered by system will not be sent instantly. It will be added to channel queue (you can find it in ChannelQueueItems in db). And then be sent out in next available time slot.(usually few seconds).

It is hard to describe a general way to test. So please read QA note of each task.