propcheck

AI-powered property-based testing CLI.

Your tests pass. Your coverage is 100%. Your code has bugs. propcheck finds them.

propcheck uses an LLM to infer properties about your code once, then runs deterministic property-based tests with fast-check / Hypothesis forever after.

Install

npm install -g propcheck fast-check

Quick Start

propcheck init
propcheck infer examples/price-utils.ts
propcheck infer --refine examples/price-utils.ts
propcheck run examples/price-utils.ts

Using an OpenAI-compatible /v1 provider:

PROPCHECK_API_KEY=sk-... \
  propcheck infer \
  --provider openai-compatible \
  --model claude-opus-4-6 \
  --base-url https://your-proxy.example/v1 \
  examples/price-utils.ts

Highlights

• TypeScript / JavaScript + Python support
• Anthropic direct API + OpenAI-compatible /v1 providers
• Trial-run validation with up to 3 rounds of self-repair before persistence
• Risk-aware persistence with status, riskTags, riskScore, and validation metadata
• Canary validation + auto-weakening for fragile numeric properties
• --refine strengthens weak properties using execution feedback
• propcheck props — list property inventory with status overview and filtering
• propcheck property — inspect or update individual property status (humanVerified tracking)
• propcheck run --changed for git-modified files only
• propcheck run --skip, --only, and --include-quarantined for execution control
• Mutation testing via propcheck quality
• Real validation: Claude Opus 4.6 currently passes 15/15 inferred properties on examples/price-utils.ts

Property status model

infer persists properties with lifecycle metadata in .propcheck/properties.json:

• accepted — default runnable property
• risky — potentially fragile, but still kept
• refined — auto-weakened into a more stable assertion
• quarantined — skipped by default during run
• dropped — excluded from execution entirely

Managing properties

propcheck props                                    # List all properties
propcheck props --status risky                     # Filter by status
propcheck props examples/price-utils.ts --json     # JSON output for one file
propcheck property src/cart.ts prop_001            # Inspect a single property
propcheck property src/cart.ts prop_001 --status quarantined   # Update status

Using --status on propcheck property sets humanVerified: true, distinguishing human decisions from LLM defaults.

propcheck run --json now reports skipped properties explicitly, including quarantined and dropped entries, so CI can distinguish "all passed" from "some were intentionally skipped".

Links

• GitHub: https://github.com/AetherCore-Dev/propcheck
• Issues: https://github.com/AetherCore-Dev/propcheck/issues
• Full documentation: https://github.com/AetherCore-Dev/propcheck#readme

License

MIT