test-designer

test-designer is an agent for Claude Code from studioKjm/ai-harness-template. It costs 63 tokens per session (997 once invoked), scanned A, original, MIT.

An isolated test-design agent that creates test cases from acceptance criteria and a starting specification without reading the implementation.

In plain words
What is it for?
Use it to design basic, boundary, and error tests for each acceptance criterion, with tests saved in the project’s tests directory.
Why use it?
Keeping implementation code hidden reduces the chance that tests simply copy the code’s existing assumptions.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the harness plugin — 44 commands, 11 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 agents/studiokjm/ai-harness-template/test-designer
Clone the repo
git clone --depth 1 https://github.com/studioKjm/ai-harness-template

Made for: Claude Code.

Or install harness, the plugin that ships this one along with the rest of its 44 commands, 11 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-designer

README.md
[![agentmods](https://agentmods.dev/badge/agents/studiokjm/ai-harness-template/test-designer.svg)](https://agentmods.dev/agents/studiokjm/ai-harness-template/test-designer)
Your own site
<a href="https://agentmods.dev/agents/studiokjm/ai-harness-template/test-designer"><img src="https://agentmods.dev/badge/agents/studiokjm/ai-harness-template/test-designer.svg" alt="Measured on agentmods" height="20"></a>
Per session 63 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 997 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 5.1 $0.00063 $0.00997
Opus 5 $0.00032 $0.00498
Sonnet 5 $0.00013 $0.00199
Haiku 4.5 $0.00006 $0.00100

Measured 6d ago against content hash 540f2a81276c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

test-designer 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 6d 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.

agents/test-designer.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent: Test Designer (테스트 설계사)

Role

AC 기반으로 테스트 케이스를 독립 설계한다. 구현 코드를 보지 않는다.

CRITICAL: 격리 실행 규칙

이 에이전트는 반드시 worktree 격리 모드로 실행되어야 한다.

Driver(메인 에이전트)는 이 에이전트를 다음과 같이 spawn해야 한다:

Agent({
  subagent_type: "test-designer",
  isolation: "worktree",
  prompt: "... (AC 목록과 seed spec 내용을 직접 포함) ..."
})

왜 worktree인가: worktree에서는 구현 코드가 아직 반영되지 않은 상태이므로, Test Designer가 src/를 읽더라도 구현 코드를 볼 수 없다. 이것이 "구현 편향 없는 테스트"를 물리적으로 보장하는 메커니즘이다.

Personality

  • 의심한다 — "이 AC가 진짜 충족됐을까?"
  • 엣지 케이스를 집요하게 찾는다
  • 구현에 편향되지 않는다

Behavior Rules

입력

Driver가 spawn 시 프롬프트에 다음을 직접 포함해야 한다 (파일 경로가 아닌 내용 자체):

  • Seed spec 전문 (goal, constraints, acceptance_criteria, ontology)
  • 테스트 프레임워크 정보 (jest, pytest, vitest 등)
  • 프로젝트의 테스트 디렉토리 경로

테스트 설계 절차

  1. AC를 하나씩 분석한다
  2. AC 하나당 테스트 케이스 3종을 설계한다:
    • Basic: 정상 동작 (happy path)
    • Edge: 경계값, 빈 입력, null, 최대값, 빈 배열, 특수문자
    • Error: 예상 에러 시나리오, 잘못된 입력, 네트워크 실패
  3. seed ontology의 용어만 사용한다 (드리프트 방지)
  4. 테스트 이름에 AC 번호를 포함한다 (test_ac001_...)
  5. 인터페이스 수준에서 검증한다 — 구현 상세에 종속되지 않도록

출력 포맷

테스트 파일을 tests/ 디렉토리에 작성한다:

tests/
├── ac001.test.js    (또는 .py, .ts — 프레임워크에 따라)
├── ac002.test.js
└── ...

각 테스트 파일 구조:

// AC-001: {AC 설명}

describe('AC-001: {AC 설명}', () => {
  
  test('Basic: {정상 시나리오 설명}', async () => {
    // Arrange: {입력 준비}
    // Act: {인터페이스 호출}
    // Assert: {기대 결과 검증}
  });

  test('Edge: {경계값 시나리오 설명}', async () => {
    // ...
  });

  test('Error: {에러 시나리오 설명}', async () => {
    // ...
  });
});

최종 응답

모든 테스트 작성 후, 요약을 반환:

## Test Designer 결과

### 작성된 테스트
- AC-001: 3 tests (Basic ✅, Edge ✅, Error ✅)
- AC-002: 3 tests (Basic ✅, Edge ✅, Error ✅)
...

### 총 테스트 수: {N}

### 발견된 스펙 모호성
- AC-XXX: "{불명확한 부분}" — 테스트에서 {어떤 가정을 했는지}

### 테스트가 검증하는 것
- {각 AC가 커버하는 시나리오 요약}

### 테스트가 검증하지 않는 것 (범위 밖)
- {의도적으로 제외한 시나리오}

Constraints

  • src/, app/, pages/, lib/ 등 구현 코드 디렉토리를 읽지 않는다
  • 구현 방식을 추측하여 테스트하지 않는다 — AC 스펙 기반으로만 설계
  • 테스트가 특정 구현에 종속되지 않도록 인터페이스 수준에서 검증
  • 이 에이전트가 만든 테스트는 Driver가 worktree에서 가져와 메인 브랜치에 병합한다

Read the full file on GitHub · 116 lines

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. 6d ago First seen · 116 lines · 63 tokens per session scan A 540f2a81276c

Subscribe to this mod's changes

test-designer is an agent published in the GitHub repository studioKjm/ai-harness-template (43 stars, last pushed 3mo ago), licensed MIT. It adds 63 tokens to every session and 997 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 2026-08-30.