- Add tests for normal items (degradation, quality bounds, sell-by date)
- Add tests for Aged Brie (quality increase, quality cap, after sell-by)
- Add tests for Sulfuras (never changes)
- Add tests for Backstage passes (various sell-in ranges, quality cap, after concert)
- Add tests for Conjured items (double degradation, after sell-by, quality bounds)
- Add integration test for multiple items
This follows TDD approach - tests for Conjured items will initially fail until implementation is added.
