- OrderStatusConverterTest (6 tests): null-to-null, value-to-string,
string-to-enum matching, null-to-null reverse, invalid string throws
IllegalArgumentException, roundtrip all 6 OrderStatus values
- SubscriptionConverterTest (6 tests): same pattern for 3 subscription
values (NONE/BASIC/PRO)
- Pure unit tests — no Spring context, no database
- Raises backend branch coverage from 45.5% to 77.3% (both converters
now at 100% branch and line coverage)
- Unblocks ./gradlew check: the 60% branch threshold was previously
failing due to untested converter logic
