Chaos Engineering
Deliberately injecting failures into a production-like system to verify it actually survives them, instead of hoping it would.
Chaos engineering (popularized by Netflix’s Chaos Monkey) runs controlled experiments that deliberately break things in production or a production-like environment — killing an instance, adding network latency, cutting off a dependency — to verify the system’s failure-handling actually works, rather than trusting an architecture diagram that says it should. It converts "we assume this is resilient" into a tested, repeatable claim.