tdd

tdd is a skill for Claude Code, Codex from HumanDealer/vibeproof. It costs 60 tokens per session (445 once invoked), scanned A, original, MIT.

A test-first development process, commonly called TDD, where tests are written before the code they check.

In plain words
What is it for?
It takes each build step from docs/PLAN.md, writes a test, confirms it fails for the right reason, adds the minimum code to pass it, and then cleans up while keeping the test passing.
Why use it?
It makes the expected behavior explicit and prevents a passing test run from giving false confidence when no test actually covers the new work.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It takes each build step from docs/PLAN.md, writes a test, confirms it fails for the right reason, adds the minimum code to pass it, and then cleans up while keeping the test passing.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/humandealer/vibeproof/tdd
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.

Any agent
npx skills add HumanDealer/vibeproof --skill tdd
Clone the repo
git clone --depth 1 https://github.com/HumanDealer/vibeproof

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for tdd

README.md
[![agentmods](https://agentmods.dev/badge/skills/humandealer/vibeproof/tdd/github.svg)](https://agentmods.dev/skills/humandealer/vibeproof/tdd)
Your own site
<a href="https://agentmods.dev/skills/humandealer/vibeproof/tdd"><img src="https://agentmods.dev/badge/skills/humandealer/vibeproof/tdd/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.

agentmods 80×15 button for tdd

Your own site · 80×15
<a href="https://agentmods.dev/skills/humandealer/vibeproof/tdd"><img src="https://agentmods.dev/badge/skills/humandealer/vibeproof/tdd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 445 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00060 $0.00445
Opus 5 $0.00030 $0.00222
Sonnet 5 $0.00012 $0.00089
Haiku 4.5 $0.00006 $0.00044

Measured 10d ago against content hash bea02cd213d8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

tdd 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.

skills/tdd/SKILL.md · 36 lines

What it actually says

tdd — test first, then code

The difference between looking senior (running tests) and being senior: the test is written first and defines what correct means. A non-coder can't read the implementation — but they can read "given a logged-out user, the page redirects to login" and confirm that's what they wanted.

The loop (per build step in PLAN.md)

  1. RED — write the test from the PLAN test list. Run it. Watch it FAIL. A test that passes before you write code tests nothing. Confirm it fails for the right reason.
  2. GREEN — write the minimum code to make it pass. Run it. Watch it PASS.
  3. REFACTOR — clean the code (names, duplication, clarity) with the test still green. This is where "clean code a Meta senior would write" happens.
  4. Check the box in PLAN.md. Next step.

Rules

  • One behavior per test. Name it so a non-coder understands: test_logged_out_user_redirects_to_login.
  • Never delete a failing test to make the bar green. Fix the code or the spec.
  • No skip/xfail without a comment + reason. A skipped test is a lie about coverage.
  • New or changed behavior → a test exercises it. If vibeproof check later shows tests passing but you wrote no test, you skipped the contract.

Verify

After GREEN, run vibeproof check. The verdict line must show tests passing with a real count (e.g. tests ok: 14 passed), not 0 passed or skipped.

Next: build the remaining steps, then /ship.

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. 10d ago First seen · 36 lines · 60 tokens per session scan A bea02cd213d8

Subscribe to this mod's changes

tdd is a skill published in the GitHub repository HumanDealer/vibeproof (2 stars, last pushed 3mo ago), licensed MIT. It adds 60 tokens to every session and 445 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.

Related

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