- Add 'performance' marker to pytest.ini - Add pytestmark to test_cache_performance.py - Use -m 'not performance' by default in addopts - Allows manual execution with 'pytest -m performance'
- Add Hypothesis property-based tests (19 tests) - Add Syrupy snapshot tests (7 tests) - Add pytest-benchmark performance tests (11 tests) - Fix Hypothesis plugin compatibility by creating MockModule class - Update pytest.ini to exclude .hypothesis directory - Add .hypothesis/ to .gitignore - Update requirements-dev.txt with testing dependencies - Mark Phase 4 complete in backend-testing-improvement-plan.md All 947 tests passing.