Library › Book 15 › Transactions -- The Safety Net
Transactions -- The Safety Net
7.1🔒What Are Transactions?Transactions ensure that a series of database operations are atomic -- they either all succeed or all fail. There is no partial state. This…
7.2🔒ACID Properties
7.3🔒Transaction-Based Test IsolationThe most powerful pattern for test data management: wrap each test in a transaction and roll it back afterward. The database returns to its…
7.4🔒Transaction Limitations
7.5🔒Cleanup Fixtures for API TestsFor API tests where rollback is not possible, use cleanup fixtures instead:
7.6🔒Savepoints -- Nested TransactionsSavepoints allow partial rollback within a transaction:
7.7🔒Read-Only Production AccessCommon Mistake: Using the same database credentials for test setup and production verification. Always use separate credentials. Production…
7.8🔒Practice Schema 7: Financial Accounts
7.9🔒ExercisesBeginner:
7.10🔒Q&AResume phrasing- Implemented transaction-based test isolation (BEGIN/ROLLBACK) that eliminated test data pollution and reduced test suite flakiness by 75%…
7.11🔒Q&ACover letter framingTest isolation is the difference between a test suite you trust and one you restart when it fails. I use transaction-based isolation…
7.12🔒Q&AInterview framing"I approach test isolation by defaulting to transaction rollback: wrap each test in BEGIN, run the test, ROLLBACK. The database returns to…
7.13🔒Q&AWhat not to say- "I just truncate all tables between tests." -- This is slow and destroys data that other parallel tests might need. - "I do not worry…
7.14🔒Q&AQuestion 1Prompt: Your test suite has 500 tests that each create data via the API. The suite takes 45 minutes to run because each test cleans up its…
7.15🔒Q&AQuestion 2Prompt: You are testing a fund transfer feature. The transfer involves debiting one account, crediting another, and creating a transfer…
7.16🔒Q&AQuestion 3Prompt: Your team wants to run verification queries against the production database after each deployment. What safeguards would you…