test-driven-development

test-driven-development is a skill for Claude Code, Codex from Dannykkh/skill-olympus. It costs 47 tokens per session (2,671 once invoked), scanned A, original, MIT.

A strict test-first development workflow, commonly called TDD. TDD means writing a test, seeing it fail, then writing the smallest amount of code needed to make it pass.

In plain words
What is it for?
Use it when explicitly following a test-first process, with supported test tools such as Vitest, Jest, pytest, Maven, .NET, or Go testing.
Why use it?
It helps verify that tests check the intended behaviour and keeps implementation changes focused.

Skill for Claude CodeCodex

Part of the skill-olympus plugin — 95 skills, 6 commands, 42 agents shipped together

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.

agentmods
npx agentmods add skills/dannykkh/skill-olympus/test-driven-development
Any agent
npx skills add Dannykkh/skill-olympus --skill test-driven-development
Clone the repo
git clone --depth 1 https://github.com/Dannykkh/skill-olympus

Made for: Claude Code, Codex.

Or install skill-olympus, the plugin that ships this one along with the rest of its 95 skills, 6 commands, 42 agents.

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 test-driven-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/dannykkh/skill-olympus/test-driven-development.svg)](https://agentmods.dev/skills/dannykkh/skill-olympus/test-driven-development)
Your own site
<a href="https://agentmods.dev/skills/dannykkh/skill-olympus/test-driven-development"><img src="https://agentmods.dev/badge/skills/dannykkh/skill-olympus/test-driven-development.svg" alt="Measured on agentmods" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,671 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00047 $0.02671
Opus 5 $0.00023 $0.01336
Sonnet 5 $0.00009 $0.00534
Haiku 4.5 $0.00005 $0.00267

Measured 2d ago against content hash 1aaad7684ba8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

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 2d 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/test-driven-development/SKILL.md · 359 lines

How it starts

The opening of the file, as written. The whole thing — 359 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Test-Driven Development (TDD)

Overview

Write the test first. Watch it fail. Write minimal code to pass.

Core principle: If you didn't watch the test fail, you don't know if it tests the right thing.

Violating the letter of the rules is violating the spirit of the rules.

Step 0: 테스트 프레임워크 자동 감지

TDD 시작 전 프로젝트의 테스트 환경을 감지합니다:

# 프레임워크 감지
_TEST_CMD=""
[ -f "package.json" ] && grep -q "vitest" package.json && _TEST_CMD="npx vitest run"
[ -f "package.json" ] && grep -q "jest" package.json && _TEST_CMD="npx jest"
[ -f "pytest.ini" ] || [ -f "pyproject.toml" ] && grep -q "pytest" pyproject.toml 2>/dev/null && _TEST_CMD="pytest"
[ -f "pom.xml" ] && _TEST_CMD="mvn test"
[ -f "*.csproj" ] && _TEST_CMD="dotnet test"
[ -f "go.mod" ] && _TEST_CMD="go test ./..."

echo "TEST_CMD: ${_TEST_CMD:-감지 실패 — 사용자에게 확인}"
감지 패턴 프레임워크 단일 파일 실행 전체 실행
vitest in package.json Vitest npx vitest run path/to/test.ts npx vitest run
jest in package.json Jest npx jest path/to/test.ts npx jest
pytest.ini / pyproject.toml pytest pytest path/to/test.py pytest
pom.xml JUnit/Maven mvn test -pl module -Dtest=TestClass mvn test
*.csproj xUnit/NUnit dotnet test --filter ClassName dotnet test
go.mod Go testing go test ./pkg/... go test ./...
없음 - 사용자에게 확인 -

파일 위치 컨벤션:

프레임워크 테스트 파일 위치 네이밍
Vitest/Jest src/__tests__/ 또는 *.test.ts {name}.test.ts
pytest tests/ test_{name}.py
JUnit src/test/java/ {Name}Test.java
xUnit *.Tests/ {Name}Tests.cs
Go 같은 디렉토리 {name}_test.go

The Iron Law

NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST

Write code before the test? Delete it. Start over.

No exceptions:

  • Don't keep it as "reference"
  • Don't "adapt" it while writing tests
  • Don't look at it
  • Delete means delete

Read the full file on GitHub · 359 lines

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.

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. 2d ago First seen · 359 lines · 47 tokens per session scan A 1aaad7684ba8

Subscribe to this mod's changes

test-driven-development is a skill published in the GitHub repository Dannykkh/skill-olympus (5 stars, last pushed 4d ago), licensed MIT. It adds 47 tokens to every session and 2,671 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 2026-09-03.