[jwilliams]

This post confuses me a little. With my tests I try not to "reach inside" systems unless it's quite a specific integration test. Especially databases. In this case I feel like we're just... testing known PostgreSQL behavior?

Or to put another way; as others have observed, this could be solved with atomic updates and in some case SERIALIZABLE. These are right tools for balance operations - and if they’re used I’m not sure they need testing in this manner?

[lirbank]

Fair concern about reaching inside systems - it's not something to do lightly. The hooks are designed to be minimal: production code never calls them, they only activate in tests. But the core point is narrower than the thread might suggest - the article isn't about whether to use atomic updates vs locks vs SERIALIZABLE. It's about when your code has operations that could race, how do you prove your handling actually works?

[jwilliams]

Fair enough and no disagreement there. Perhaps (for me!) the example pulled against it your core point.