Add comprehensive tests for the ValidateSession wrapper function covering:
- Non-existent token (returns false)
- Empty token (returns false)
- Valid token (returns true)
- Expired token (returns false)
The ValidateSession function is a simple wrapper around the SessionStore's
ValidateSession method, but having direct tests ensures the wrapper is
exercised and documents its expected behavior.
Coverage: ValidateSession 0% → 100%
rcourtman
347f75541c