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 skills add johnku2011/boilerplates-with-ai-skills --skill test-driven-developmentgit clone --depth 1 https://github.com/johnku2011/boilerplates-with-ai-skillsWrote 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/johnku2011/boilerplates-with-ai-skills/test-driven-development)<a href="https://agentmods.dev/skills/johnku2011/boilerplates-with-ai-skills/test-driven-development"><img src="https://agentmods.dev/badge/skills/johnku2011/boilerplates-with-ai-skills/test-driven-development/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/johnku2011/boilerplates-with-ai-skills/test-driven-development"><img src="https://agentmods.dev/badge/skills/johnku2011/boilerplates-with-ai-skills/test-driven-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 5.1 | $0.00041 | $0.00723 |
| Opus 5 | $0.00020 | $0.00362 |
| Sonnet 5 | $0.00008 | $0.00145 |
| Haiku 4.5 | $0.00004 | $0.00072 |
Grade A, and why
test-driven-development 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 10d 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 — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test-Driven Development
Overview
Write a failing test before production code. Keep each cycle small and verify
with this project's test command (see AGENTS.md).
Core principle: If you did not watch the test fail, you do not know if it tests the right thing.
Iron law: No production code without a failing test first.
When to Use
Always:
- New features
- Bug fixes
- Behavior changes
Exceptions (ask your human partner):
- Throwaway prototypes
- Generated code
- Pure configuration with no runtime behavior
Red-Green-Refactor
- RED — Write one minimal test for one behavior. Run it; confirm it fails for the expected reason (missing feature, not a typo).
- GREEN — Write the smallest code that passes. Run the full suite.
- REFACTOR — Clean up while staying green. Do not add behavior.
- Repeat for the next increment.
Guidelines
- Prefer many small tests over one large test.
- Test observable behavior (HTTP status/body, CLI output, return values), not private implementation details.
- Run
npm testafter every change; do not claim completion on a red suite. - Keep tests deterministic: no wall-clock timing, network, or ordering flakes.
- For UI or native screens, unit-test pure logic under
src/; verify layout on a simulator only when the change is visual. - Use real code in tests; mock only at unavoidable boundaries.
Verification Checklist
Before marking work complete:
- Every new function or route has a test
- Watched each new test fail before implementing
- Failure was due to missing behavior, not setup errors
- Wrote minimal code to pass each test
- Full test suite passes
- No new warnings in test output
If you cannot check every box, you skipped TDD — start over.
Bug Fixes
- Write a failing test that reproduces the bug.
- Fix with minimal code.
- Keep the test — it prevents regression.
Never fix bugs without a test.
Common Rationalizations
| Excuse | Reality |
|---|---|
| "Too simple to test" | Simple code breaks. A test takes seconds. |
| "I'll test after" | Tests that pass immediately prove nothing. |
| "Already manually tested" | Manual checks are not repeatable in CI. |
| "Deleting code is wasteful" | Unverified code is debt. Delete and rewrite with TDD. |
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.
- 10d ago First seen · 96 lines · 41 tokens per session scan A 09198990dece
test-driven-development is a skill published in the GitHub repository johnku2011/boilerplates-with-ai-skills (240 stars, last pushed 16d ago), licensed MIT. It adds 41 tokens to every session and 723 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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engram-testing-coverage
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iterative-development
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python
Python development with ruff, mypy, pytest - TDD and type safety.
nw-fp-clojure
Clojure language-specific patterns, data-first modeling, REPL-driven development, and spec.
strict-tdd
Strict RED->GREEN->REFACTOR test-driven development with enforcement. Never write production code before a failing test. Atomic commits per TDD cycle.
mobiai-mobile-tdd
You MUST use this before writing any implementation code for a mobile feature, bug fix, refactor, or behavior change. Tests come before implementation — no exceptions.