Add 40 unit tests for backend/app/workers/tasks.py (9% → 96% coverage)

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Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

CHANGELOG.md

@@ -19,6 +19,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- **Celery tasks test coverage**: Added 40 unit tests for `backend/app/workers/tasks.py`, raising coverage from 9.22% to 96%. Tests cover `_as_utc` helper, `process_mail_account` (Gmail API and SMTP forwarding, credential revocation, empty-email detection, error handling), `process_all_enabled_accounts` (stale-run cleanup, interval checking), and `cleanup_old_logs` (data retention, stale-run recovery).
+
 - **Domain-based logo fallback for mail accounts**: `ProviderLogoBanner` now shows provider logos even for accounts that have no `provider_name` set, by extracting the domain from the email address and matching it against a new `DOMAIN_ICON_MAP`. Covers Gmail, GMX, WEB.DE, Yahoo Mail, AOL, T-Online, Outlook/Hotmail, IONOS, Freenet, iCloud, Posteo, and Proton Mail.
 
 ### Fixed

docs/TODO.md

@@ -115,12 +115,12 @@ Comprehensive task breakdown for repository improvements and production readines
 - [x] Write unit tests for schemas and validation
 - [x] Write unit tests for application factory and core endpoints
 - [x] Reach 50%+ test coverage (currently 59%)
+- [x] Write tests for Celery tasks (96% coverage for `tasks.py`)
 
 ### In Progress 🔨
 - [ ] Write unit tests for authentication (target 80%+ coverage)
 - [ ] Write unit tests for mail processing
 - [ ] Write integration tests for API endpoints
-- [ ] Write tests for Celery tasks
 
 ### Not Started 📋
 - [ ] Add end-to-end tests