>Deterministic simulation. Another lightweight method widely used at AWS is deterministic simulation testing, in which a distributed system is executed on a single-threaded simulator with control over all sources of randomness, such as thread scheduling, timing, and message delivery order. Tests are then written for particular failure or success scenarios, such as the failure of a participant at a particular stage in a distributed protocol. The nondeterminism in the system is controlled by the test framework, allowing developers to specify orderings they believe are interesting (such as ones that have caused bugs in the past). The scheduler in the testing framework can also be extended for fuzzing of orderings or exploring all possible orderings to be tested.
This is fucking amazing