Stress testing

Stress suite. Hrubí časti app, ktorých zlyhanie stojí používateľov peniaze — hlavne copy trading — s nehostinnými, randomizovanými, fault-injected workloadmi. Assertuje systém zostáva korektný. Žije v tests/StressTests, beží v normálnom dotnet test green gate.

Prístup — Deterministic Simulation Testing (DST)

Najlepší spôsob stress testovania distribuovaných finančných systémov = deterministic simulation testing, per TigerBeetle, FoundationDB, Antithesis: beží reálnu logiku proti simulovanému svetu, hnané so seeded random workload + injected faults, assertuje invariants at quiescence. Všetko seeded + deterministic → akékoľvek zlyhanie reprodukuje presne zo seed. Kombinované s:

• Chaos-engineering fault injection (Netflix Chaos Monkey štýl) — connection drops, order rejections, token rotation, node death.
• Property-based invariants — neassertuje exact call sequences; assertuje vlastnosti, ktoré musia platiť bez ohľadu na to, ako sa udalosti prelínajú (convergence, no orphans, at-most-one lease holder).

App už lodive perfektný DST svet model: FakeTradingSession, cTrader-faithful in-memory Open API session. Stress suite ho znova používa (linked, single source of truth) nie mock, takže simulated broker sa správa ako reálny.

Čo pokrýva

Copy trading (primárny focus)

Hnané cez CopyDstWorld (tests/StressTests/CopyTrading/), beží live CopyEngineHost proti fake session, vydáva membership-konzistentný source workload:

Scenár	Stresuje
Mass_fan_out…	1 source → 80 destinations, 150 opens then closes; full fan-out + drain
High_frequency_open_close…	300 rapid interleaved open/close; no leaked positions
Partial_close_and_scale_in_storm…	partial-close + scale-in churn; label-set stability
Connection_flap_storm…	repeated socket disconnect/reconnect + mid-flight desync; resync convergence
Order_rejection_cascade…	a subset rejects every order; healthy destinations unaffected, then self-heal via resync
Token_rotation_storm…	rapid in-place token swaps during an order storm
Randomized_chaos_workload… (10 seeds)	the DST core — every event type + every fault interleaved unpredictably
CopyLeaseReclaimStressTests	node death + lease reclaim across a scaled cluster (pure domain, FakeTimeProvider)

Convergence invariant. At rest, every healthy destination mirrors exactly set of still-open source positions — no orphans, none missing. Asserted on label set (scale-in legitimately opens second destination position under same source label, so duplicate labels expected). Destination currently rejecting orders allowed to lag, reconciled once healed.

Lease invariant. In cluster where nodes die + revive on seeded schedule, at most one node ever holds valid lease on a profile; dead node's lease lapses exact at expiry, gets reclaimed; healthy cluster settles with every profile held by exact one node. Mirrors CopyEngineSupervisor's claim predicate against CopyProfile domain lease methods.

Thread-safety of the harness

FakeTradingSession single-threaded; stress workload ho mutuje z test threadu kým host číta/píše z jeho loop. SyncTradingSession ho wrapuje, robí každú session operáciu atomickú na jednej bráne (bez držania brány naprieč reconnect callback — by invertovalo lock order vs host's _stateGate a deadlock-nulo). Simulator samotný nedotknutý.

Bugs nájdené

• Startup resync race v CopyEngineHost. OnReconnected zapojené pred iniciálnym reference-load + first resync, čo bežalo bez _stateGate. Socket flap počas startup run-nul druhé resync súbežne + korumpovalo host's non-concurrent state dicts (_symbolDetails, _sourceVolumes). Opravené: bež startup load + first resync pod bránou. Produkčná race, nie test artifact — DST chaos workload to surface-nul.

Bežanie

dotnet test tests/StressTests/StressTests.csproj

Suite serializovaná ([assembly: CollectionBehavior(DisableTestParallelization = true)]): každý test spíní live host background loop, hná k quiescencii pod wall clock, takže parallel run starves host tasks a makes convergence timeouts flaky. Workloads dimensionované na dokončenie v sekundách takže suite zostáva v default green gate. Failure vytlačí its seed; re-run that seed pre reprodukciu presného interleaving.

Rozširovanie

• Nové copy správanie → pridaj source op do CopyDstWorld (udržiavaj source book membership konzistentné s event stream) + weighted case in CopyChaosDstTests. Ak môže vytvoriť alebo retirovú destination position, uistite sa, že convergence invariant stále drží.
• Nový fault → pridaj injector do CopyDstWorld (deleguj na FakeTradingSession's control surface cez SyncTradingSession) + exercise in a named scenario plus chaos mix.
• Udržiavaj simulátor cTrader-faithful (pozrite root CLAUDE.md mandát); nikdy ho neoslabuj pre passing stress testu.