Soak Testing
Soak testing (also called endurance testing) runs a system under sustained load for an extended period — hours or days rather than minutes — to catch problems that only emerge over time, like memory leaks, resource exhaustion, or gradual performance degradation invisible in a short test.
A short load test can pass cleanly while a system slowly leaks memory or accumulates unclosed database connections under the hood — problems that don't manifest as a failure until hours later, once the leaked resource finally runs out. Soak testing exists specifically to surface that class of slow-building failure before it happens in production instead of after.
It's the performance-testing equivalent of asking "does this hold up over a long shift, not just a sprint" — genuinely time-consuming to run, which is why it's typically reserved for major releases or infrastructure changes rather than run on every single deploy.
