jepsen-fault-testing

name	jepsen-fault-testing
description	Jepsen-style distributed system fault injection patterns. Network partition simulation, clock skew injection, process kill scenarios, linearizability checkers, and fault-tolerance test design. Sources: jepsen-io/jepsen (EPL-1.0).

/jepsen-fault-testing

When to Use

• Verify that distributed agent consensus (Raft, etcd) actually survives network splits
• Prove that the distributed mutex never grants two agents the lock simultaneously
• Chaos test before a production deployment of a multi-node agent cluster
• Validate that CRDT merges produce linearizable results after partitions

Do NOT use for

• Unit tests of business logic (use Jest [[jest-test-generation]])
• Performance benchmarking (Jepsen introduces intentional faults, not load)

---

Jepsen test anatomy (Clojure DSL — conceptual)

;; A Jepsen test has 5 components:
{:name    "yamtam-raft-lock"
 :db      (raft-cluster-db)         ; setup/teardown cluster
 :client  (lock-client)             ; operations: acquire/release
 :nemesis (nemesis/partition-random-halves)  ; fault injector
 :checker (checker/linearizable)    ; correctness verifier
 :generator
   (->> (gen/mix [acquire-op release-op])
        (gen/stagger 0.1)           ; 100ms between ops
        (gen/nemesis
          (gen/seq [{:type :info :f :start}  ; inject partition
                    (gen/sleep 10)
                    {:type :info :f :stop}])) ; heal
        (gen/time-limit 60))}       ; 60s test

---

Node.js fault injection patterns (without Jepsen)

// Simulate network partition: drop packets between agent-1 and agent-2
// Requires iptables or tc (traffic control)
import { exec } from 'child_process'
 { promisify }  
 run = (exec)

  () {
  
   ()
   ()
  .()
}

  () {
   ()
   ()
  .()
}