A test-first development skill. TDD means writing a test before the code, confirming that the test fails, and then writing the smallest code that makes it pass.

It is for implementing features and bug fixes with tests written before the implementation.

It helps ensure tests check real behavior instead of passing without first proving that they can catch a problem.

How rbergman/claude-haskell-starter configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to rbergman/claude-haskell-starter. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/rbergman/claude-haskell-starter/main/.claude/skills/tdd/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/rbergman/claude-haskell-starter

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/rbergman/claude-haskell-starter/tdd/github.svg)](https://agentmods.dev/skills/rbergman/claude-haskell-starter/tdd)

Your own site

<a href="https://agentmods.dev/skills/rbergman/claude-haskell-starter/tdd"><img src="https://agentmods.dev/badge/skills/rbergman/claude-haskell-starter/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/rbergman/claude-haskell-starter/tdd"><img src="https://agentmods.dev/badge/skills/rbergman/claude-haskell-starter/tdd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,172 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 unknown 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.

Model	Per session	Once invoked
Fable 5.1	$0.00041	$0.02172
Opus 5	$0.00020	$0.01086
Sonnet 5	$0.00008	$0.00434
Haiku 4.5	$0.00004	$0.00217

Measured 9d ago against content hash 025a4a199bad, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, 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 9d 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.

.claude/skills/tdd/SKILL.md · 350 lines

The source is not reproduced here

No licence file

Read it on GitHub

Files

What ships with it

1 file 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.

references/testing-anti-patterns.md 6.6 KB

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.

9d ago First seen · 350 lines · 41 tokens per session scan A 025a4a199bad

Subscribe to this mod's changes

tdd is a skill published in the GitHub repository rbergman/claude-haskell-starter (5 stars, last pushed 8mo ago), with no licence file. It adds 41 tokens to every session and 2,172 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 2026-08-31.

TDD Testing

engram-testing-coverage

TDD and coverage standards for Engram. Trigger: When implementing behavior changes in any package.

Gentleman-Programming/engram · 25 tokens

nw-fp-clojure

Clojure language-specific patterns, data-first modeling, REPL-driven development, and spec.

nWave-ai/nWave · 25 tokens

strict-tdd

Strict RED->GREEN->REFACTOR test-driven development with enforcement. Never write production code before a failing test. Atomic commits per TDD cycle.

a5c-ai/babysitter · 34 tokens

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.

ArisGuimera/MobiAI-Core · 38 tokens

tdd

This skill should be used when the user wants to implement features or fix bugs using test-driven development. Enforces the RED-GREEN-REFACTOR cycle with vertical slicing, context isolation between test writing and implementation, human checkpoints, and auto-test feedback loops. Uses multi-agent orchestration with the…

glebis/claude-skills · 92 tokens

conductor-implement

Execute tasks from a track's implementation plan following TDD workflow.

rmyndharis/antigravity-skills · 17 tokens

claude-haskell-starter: Skill for Claude Code