Tdd

QA filed a one-line gap: no concurrency tests on the stock pool. I opened the file expecting to write four tests and close it in an afternoon. Instead I found that the lock those tests were supposed to cover was not there anymore. What can go wrong here The system is a promotions backend. Several campaigns draw from one shared stock pool per SKU. Before a campaign can reserve units, a service reads the pool balance, subtracts what is already reserved, and writes an allocation. ...