How to test cron tasks in Docker? (how to speed up time)?

Question

linux

There is a Python (Flask + Celery mysql, redis) project.
Tasks are set for celery, which must be completed according to the schedule.
It is necessary to check that after N hours, or at the moment of time transition (or other problems and situations that may arise) are processed correctly.
Waiting a day/week/year for this is naturally not an option.
Changing the time in docker is not available.
How to solve this problem? (correct or fast)

Answer 1

Do you want to test Cron? That he will start at exactly the right time? Or do you still want to test the operation of a scheduled task?
Cron, I think, does not need testing. But the task can be covered with tests. And don't do magic.

Answer 2

Make a trigger for every 5 minutes and check that the job is working, then change the scheduling to the correct one.

Answer 3

Google it: celery task monitoring, Flower