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.
npx agentmods add skills/int2t05/engineering-skills/api-testingnpx skills add int2t05/engineering-skills --skill api-testinggit clone --depth 1 https://github.com/int2t05/engineering-skillsWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00056 | $0.01079 |
| Opus 5 | $0.00028 | $0.00540 |
| Sonnet 5 | $0.00011 | $0.00216 |
| Haiku 4.5 | $0.00006 | $0.00108 |
Grade A, and why
api-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.
How it starts
The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Testing Patterns
API testing verifies contracts and behavior from the consumer perspective — correct responses, proper error handling, acceptable performance. Focus on what matters to consumers, not implementation details.
When to use
- Testing REST or GraphQL APIs
- Validating microservice contracts
- Designing API test strategies
- Preventing breaking API changes
- Triggers on "test API", "contract testing", "integration test", "API 测试", "接口测试", "契约测试"
Not for: generating test scaffolds for non-API code (use test-generation); browser/E2E flows (use e2e-testing); the TDD loop itself (use tdd).
Steps
1. Identify the testing level
| Level | Purpose | Dependencies | Speed |
|---|---|---|---|
| Contract | Provider-consumer agreement | None | Fast |
| Component | API in isolation | Mocked external deps | Fast |
| Integration | Real dependencies | Database, services | Slower |
2. Test the contract, not implementation
Test from the consumer perspective using schema validation, not exact values. Consumers depend on the contract (status codes, response shape); they don't care about internal structure.
Pattern — Consumer-Driven Contracts: schema validation against the contract (status codes, response shape), not exact values — code example in references/templates/api-test-scaffold.md. Use Pact or Spring Cloud Contract for consumer-driven contract testing in microservice architectures.
3. Cover critical scenarios
| Scenario | Must test | Example |
|---|---|---|
| Auth | 401/403 handling | Expired token, wrong user, cross-user access |
| Input | 400 validation | Missing fields, wrong types, out-of-range values |
| Errors | 500 graceful handling | DB down, timeout, upstream failure |
| Idempotency | Duplicate prevention | Same idempotency key → same result |
| Concurrency | Race conditions | Parallel checkout on shared inventory |
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 2d ago First seen · 116 lines · 56 tokens per session scan A fde3a28200ba
api-testing is a skill published in the GitHub repository int2t05/engineering-skills (3 stars, last pushed 14d ago), licensed MIT. It adds 56 tokens to every session and 1,079 once invoked, about $0.0003 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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systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
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You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.
writing-skills
Use when creating new skills, editing existing skills, or verifying skills work before deployment.
finishing-a-development-branch
Use when implementation is complete, all tests pass, and you need to decide how to integrate the work.
test-driven-development
Use when implementing any feature or bugfix, before writing implementation code.
receiving-code-review
Use when receiving code review feedback, before implementing suggestions, especially if feedback seems unclear or technically questionable - requires technical rigor and verification, not performative agreement or blind implementation.