Deterministic Simulation Testing

Deterministic Simulation Testing (DST) is a testing methodology for distributed systems where the time wheel, scheduler, and I/O driver are replaced with deterministic mocks, enabling fully reproducible execution of concurrent system behaviors. FoundationDB pioneered this approach, and it has become a gold standard for verifying distributed system correctness.

In the Rust ecosystem

compio's pluggable driver-executor architecture is the only Rust thread-per-core runtime that supports DST. Because the I/O driver is decoupled from the executor, test harnesses can inject deterministic time, network partitions, and disk failures while replaying the exact same execution sequence. apache-iggy cited this capability as critical to their choice of Compio over monoio and glommio, whose drivers and executors are tightly coupled.