Borrowing it
Nothing to install: this file belongs to webhook-co/webhook. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/webhook-co/webhook/main/.cursor/skills/test-driven-development/SKILL.mdgit clone --depth 1 https://github.com/webhook-co/webhookWrote 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/webhook-co/webhook/test-driven-development)<a href="https://agentmods.dev/skills/webhook-co/webhook/test-driven-development"><img src="https://agentmods.dev/badge/skills/webhook-co/webhook/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/webhook-co/webhook/test-driven-development"><img src="https://agentmods.dev/badge/skills/webhook-co/webhook/test-driven-development.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00054 | $0.00706 |
| Opus 5.5 | $0.00022 | $0.00282 |
| Sonnet 5.5 | $0.00011 | $0.00141 |
| Haiku 4.5 | $0.00005 | $0.00071 |
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 1mo 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 — 57 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test-driven development
Write the test first, watch it fail, then make it pass. This is how the correctness-critical paths here stay correct: Standard Webhooks signing/verification (send + receive), dedup/idempotency, retry/ backoff (DO Alarms), FIFO ordering (one DO per endpoint), replay-to-localhost, and single-dimension metering.
The loop (don't skip a step)
- Red — write a failing test. Capture the desired behavior as a test before touching implementation. Assert the right outcome (status code, ordering, exactly-once effect), not just that code runs. Run it and watch it fail for the expected reason. A test that passes immediately, or fails for the wrong reason, isn't testing what you think.
- Green — minimum code to pass. Write the least implementation that makes the test pass. No gold-plating, no unrelated changes.
- Refactor — clean up under green. With the test green, improve names, structure, and duplication. Re-run; stay green.
Every bug fix starts with a regression test that fails without the fix. No behavior change lands without a test that exercises it, including the unhappy path.
What to cover
- Boundary validation of all external input (webhook bodies, API params, MCP tool input).
- Edge cases: malformed/oversized payloads, duplicate deliveries, out-of-order events, clock skew, partial failures, retries to exhaustion, replay idempotency, signature mismatch/expiry.
- Retryable-vs-terminal failure distinction, so the retry scheduler does the right thing.
- Prefer
vitestwith the Cloudflare Workers pool for DO/Workers code so tests run against the real runtime.
The gate is non-negotiable
This ties directly to the repo's no-skipped-tests rule and coverage thresholds:
- Never add
.only/fdescribe/it.only/describe.only, and never.skip/ disable a test to get green. Theno-skipped-testscheck (wired into lint and CI) exists precisely to stop that. - Never lower a coverage threshold to make a build pass.
- Never
git commit --no-verify/git push --no-verify. If the pre-commit/lint-staged hook fails, fix the root cause and make a new commit. Local hooks are a convenience; CI required checks are the real gate and have no bypass for anyone, including admins.
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.
- 1mo ago First seen · 57 lines · 54 tokens per session scan A 38d83e17e6c6
test-driven-development is a skill published in the GitHub repository webhook-co/webhook (0 stars, last pushed 18d ago), licensed Apache-2.0. It adds 54 tokens to every session and 706 once invoked, about $0.0002 per session on Opus 5.5. 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.
Other skills, from other repositories
skillshare-implement-feature
Implement a feature from a spec file or description using TDD workflow. Use this skill whenever the user asks to: add a new CLI command, implement a feature from a spec, build new functionality, add a flag, create a new internal package, or write Go code for skillshare. This skill enforces test-first development…
implement
Use when an approved plan and task list exist and it is time to turn them into working, tested code — the SDD phase after analyze and before verify. Enforces TDD: a failing test comes before the code that makes it pass, one task at a time, appended to a progress ledger that survives compaction. Delegates test tooling…
product
Consolidated Galyarder Framework Product intelligence bundle.
implement
Implement a technical design by decomposing it into dependency-ordered vertical slices, executing each with TDD red-green, reviewing each via an isolated sub-agent, and persisting progress to a state file so work survives session restarts. Use when the user has a tech design (doc or settled conversation) and says…
test-driven-development
Writing code with tests first: RED-GREEN-REFACTOR, reproduce bugs as failing tests before fixing, and avoid testing anti-patterns. Use when implementing behaviour, fixing a defect, or asked to add tests.
rpa-gen-rules
Use when the user invokes /rpa-gen-rules or asks to create, refresh, audit, or synchronize project instructions such as root AGENTS.md, Cursor .cursor/rules, or Claude Code .claude/rules, especially when existing rule trees have drifted.