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/caiaffa/claude-code-ultimate-engineering-system/test-strategynpx skills add caiaffa/claude-code-ultimate-engineering-system --skill test-strategygit clone --depth 1 https://github.com/caiaffa/claude-code-ultimate-engineering-systemWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/caiaffa/claude-code-ultimate-engineering-system/test-strategy)<a href="https://agentmods.dev/skills/caiaffa/claude-code-ultimate-engineering-system/test-strategy"><img src="https://agentmods.dev/badge/skills/caiaffa/claude-code-ultimate-engineering-system/test-strategy.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00030 | $0.00584 |
| Opus 5 | $0.00015 | $0.00292 |
| Sonnet 5 | $0.00006 | $0.00117 |
| Haiku 4.5 | $0.00003 | $0.00058 |
Grade A, and why
test-strategy 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 4d 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 — 54 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mission
Test the right behavior at the right layer with the least fragility and the highest confidence.
When to use
- Implementing new features.
- Fixing bugs (regression tests).
- Refactoring risky paths.
- Defining coverage for APIs, workers, queues.
- Reducing flaky or low-value tests.
Handoff
- Receives from: backend-platform-engineer (after implementation) or code-reviewer (identified gaps).
- Hands off to: code-reviewer (for final review), release-commander (for deploy).
Test layer selection
| What you're testing | Right layer | Wrong layer |
|---|---|---|
| Pure business logic (calculations, rules, transforms) | Unit test | Integration test (too slow, too coupled) |
| API contract (request → response shape, status codes) | Integration test | Unit test (misses middleware, validation) |
| Database behavior (queries, transactions, constraints) | Integration test with real DB | Unit test with mocked DB (useless) |
| Queue consumer (job lifecycle, retries, idempotency) | Integration test with real Redis | Unit test (misses BullMQ behavior) |
| Cross-service contract | Contract test | E2E test (too fragile, too slow) |
| Critical user journey | E2E (sparingly) | Everything else (too many E2E = slow CI) |
Must-test scenarios for every feature
- Happy path — normal flow works.
- Validation failures — invalid input rejected correctly.
- Error cases — what happens when dependencies fail?
- Idempotency — same request twice = same result.
- Edge cases — empty, null, max length, boundary values.
- Concurrency — two simultaneous requests for the same resource.
Must-test scenarios for bug fixes
- Regression test — exact scenario that caused the bug.
- Neighboring scenarios — similar inputs that might also fail.
Red flags — test suite is weak if
- Tests assert framework details (mock called N times) instead of behavior.
- Tests break when you refactor internals without changing behavior.
- Database behavior is mocked away for data-critical paths.
- No test exercises the retry/failure path.
- 100% coverage but no edge case or failure scenario tests.
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.
- 4d ago First seen · 54 lines · 30 tokens per session scan A c686b069b28e
test-strategy is a skill published in the GitHub repository caiaffa/claude-code-ultimate-engineering-system (17 stars, last pushed 2mo ago), licensed MIT. It adds 30 tokens to every session and 584 once invoked, about $0.0002 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 2026-08-30.
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