Add unit tests for CronJob.duration and CronJob.elapsed properties

[coderabbitai]

Background

The CronJob class in supertask/model.py has properties (duration, elapsed) and a method (delta_duration) that currently lack test coverage.

Required Tests

Unit tests should be added to cover:

• Finished job: When end is set, duration should return (end – start).total_seconds().
• Unfinished job: When end is None, duration should raise RuntimeError("Job has not finished yet").
• Elapsed time: When end is None, elapsed should return (now – start).total_seconds() without raising an exception.
• delta_duration: Conversion of a timedelta to seconds (e.g., 1 hour → 3600 seconds).

Suggested Implementation

Create tests under tests/ (e.g., tests/test_cronjob.py) that exercise these scenarios.

References

This issue was identified during code review:

• PR: Refactor data model and CLI. Remove HTTP service. #155
• Comment: Refactor data model and CLI. Remove HTTP service. #155 (comment)