DB migrations, async jobs, caching, concurrency, distributed tracing, saga and CQRS, serverless, and time and timezones.
Background job and queue testing for Sidekiq, Celery, BullMQ, SQS, RabbitMQ and Kafka consumers, plus cron schedules and idempotency guarantees. A read-only critic agent (async-job-health-critic) flags missing retry limits, absent dead-letter routing, and other at-least-once reliability defects in queue and worker code.
Cache testing across browser, CDN, proxy, application and data-store layers: Redis, CDN purges, Varnish VTC tests, and cache-key collision audits. Covers RFC 9111 HTTP caching, Cloudflare / Fastly / CloudFront purge APIs, browser Cache-Control tests, and cache-coherence patterns with stampede and stale-while-revalidate references. A detector agent (cache-key-collision-detector) finds keys missing a tenant, user or locale discriminator.
Concurrency testing: deterministic race-condition tests, deadlock detection, async ordering checks, and database MVCC isolation-level tests. Includes ThreadSanitizer and the Go race detector with goleak, plus a critic agent (concurrency-critic) that flags unguarded shared state and lock-ordering risks. Code-level races, distinct from qa-resilience (infrastructure fault injection).
Database migration testing for Flyway, Liquibase and Atlas: classify every schema change by risk and review blast radius and locking before it ships. Sorts DDL and DML into an eight-category operation taxonomy. A review agent (migration-blast-radius-reviewer) covers blast radius plus DDL performance: CONCURRENTLY index builds, ACCESS EXCLUSIVE rewrites, post-migration ANALYZE, and lock-time estimates.
Distributed tracing tests with OpenTelemetry: assert span names, attributes, parent links and status, and query Jaeger, Zipkin or Tempo in CI. Validates OpenTelemetry Collector pipelines and writes per-feature trace specs. A review agent (trace-coverage-reviewer) finds untraced critical paths and spans missing semantic-convention attributes.
Saga, CQRS and event sourcing tests: compensating actions, the transactional outbox, replay determinism, and projection consistency windows. A critic agent (saga-critic) flags missing compensating transactions and other distributed-transaction defects.
Serverless testing for AWS Lambda, Azure Functions and Cloudflare Workers: local emulators, cold-start and timeout budgets, and integration test suites. Builds integration tests from SAM, Serverless Framework, Wrangler, Vercel or Netlify definitions and covers .NET Lambda test tools. A critic agent (serverless-cold-start-critic) flags cold-start anti-patterns.
Time and timezone testing: fake clocks across runtimes, DST transitions, leap seconds, and timezone test matrices built from a codebase's date handling. Fake clocks cover freezegun, Jest and Sinon fake timers, timecop, java.time.Clock, .NET TimeProvider and libfaketime. A critic agent (time-handling-critic) flags naive now() calls and DST-unsafe arithmetic.
