Artillery Load Testing

Artillery Load Testing

This skill makes an AI agent author Artillery 2.x load tests as declarative YAML: realistic traffic phases, multi-step scenarios with captured variables, CSV-driven virtual user data, functional expect checks inside load flows, and ensure thresholds that turn latency regressions into red CI builds. Trigger it when a project contains artillery.yml, artillery in package.json, or when the user asks for load, stress, soak, or spike testing of an HTTP API or website in a Node.js stack.

Core Principles

1. Model traffic in phases, never one flat rate. Real load has a warm-up, a ramp, and a sustained plateau. A single arrivalRate hides cold-start effects and autoscaling lag. Always define at least warm-up, ramp, and sustain phases.
2. arrivalRate is new virtual users per second, not concurrency. Each arriving VU runs the whole scenario. If your scenario takes 10 seconds and you arrive 50/sec, you have roughly 500 concurrent users. Calculate this before picking numbers.
3. Thresholds belong in the test file, not in a wiki. Use the ensure plugin so artillery run exits non-zero when p95/p99 or error rate budgets are blown. A load test that cannot fail is a demo, not a test.
4. Assert correctness under load with expect. A server returning 200 with an empty body at p99 latency is still broken. Check statusCode, contentType, and hasProperty inside the flow.
5. Parameterize virtual users from CSV payloads. Hammering one account exercises one cache line and one DB row. Use payload with hundreds of distinct credentials and SKUs to defeat caches realistically.
6. Never load test production without a plan; never load test third parties at all. Point Artillery at a staging environment sized like production, announce test windows, and rate-limit anything that crosses a vendor boundary.

Setup

npm install --save-dev artillery@latest
npx artillery version

# Run a test locally
npx artillery run load/checkout.yml

# Save raw metrics for trend analysis
npx artillery run load/checkout.yml --output artillery-report.json