contract-testing

A testing process for services that communicate through APIs, using shared expectations, OpenAPI specifications, and automated checks for incompatible changes. OpenAPI is a versioned description of an API’s requests and responses.

In plain words
What is it for?
Use it to validate API schemas, compare specification versions, run consumer-driven Pact tests, verify providers, and maintain deterministic network mocks.
Why use it?
It catches mismatches between services and detects changes that could break software consuming an API before deployment.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/saitarrun/devforge-ai/contract-testing
Any agent
npx skills add saitarrun/Devforge-ai --skill contract-testing
Clone the repo
git clone --depth 1 https://github.com/saitarrun/Devforge-ai

Made for: Claude Code, Codex.

Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 351 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00023 $0.00351
Opus 5 $0.00012 $0.00176
Sonnet 5 $0.00005 $0.00070
Haiku 4.5 $0.00002 $0.00035

Measured 2d ago against content hash 9fb33b9acdbd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

contract-testing scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/contract-testing/SKILL.md · 31 lines

What it actually says

Contract Testing & OpenAPI Validation Skill

This skill ensures microservices communicate reliably via explicit, version-controlled contracts without breaking downstream consumers.

Core Architectural Pillars

1. OpenAPI & Schema Drift Validation

  • Spec-First & Code-First Sync: Enforce strict TypeScript/Zod/JSON Schema generation from OpenAPI 3.1 definitions.
  • Breaking Change Detection: Run oasdiff or openapi-diff in CI/CD to block backward-incompatible changes (e.g. removed fields, altered types, tightened validation).

2. Consumer-Driven Contract Testing (Pact)

  • Consumer Contracts: Downstream microservices define expected API requests and responses.
  • Provider Verification: Upstream microservice verifies actual endpoint execution against consumer expectations before deployment.
  • Pact Broker Matrix: Track deployment status across environments to prevent deploying incompatible service versions.

3. Mock Service Worker (MSW) & Integration Mocks

  • Deterministic API Fixtures: Shared MSW handlers across unit, component, and E2E tests.
  • Network Level Interception: Mock API traffic at network level to avoid fragile global fetch overrides.

Checklist for Slices with needs_contract_testing: true

  • OpenAPI 3.1 schema defined or updated
  • Breaking change check passes against main branch schema
  • Consumer Pact tests generated or MSW handlers synchronized
  • Provider endpoint verification passes end-to-end
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 31 lines · 23 tokens per session scan A 9fb33b9acdbd

Subscribe to this mod's changes

contract-testing is a skill published in the GitHub repository saitarrun/Devforge-ai (5 stars, last pushed 19d ago), licensed Apache-2.0. It adds 23 tokens to every session and 351 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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