How do you test code that depends on the current time, random values, or generated identifiers?

I also separate deterministic testing from security guarantees. A seeded pseudo-random generator is useful for test data but must not replace secure randomness in authentication or reset tokens. Property-based tests should retain the failing seed and shrink the case. For distributed workflows, I test idempotency and ordering without assuming generated ids are sequential or that clocks on different machines are perfectly aligned.