The Couchbase QA team thoroughly tests DCP Rollbacks, a critical feature for ensuring data integrity in Couchbase products. To test rollbacks, the team uses a custom DCP client to simulate various scenarios, including failovers and crashes with non-persisted data. They verify that producers request rollbacks when necessary and that consumers properly undo later mutations and apply new ones correctly. System tests also focus on hard failovers at high mutation rates, checking for stability and consistency issues such as data loss or incorrect client behavior during rollback.