fe-test-author

fe-test-author is an agent for Claude Code from sh5623/fe-rail. It costs 38 tokens per session (2,247 once invoked), scanned A, original, MIT.

A frontend test-writing agent that derives behavior scenarios and creates tests from a user's point of view. BDD describes behavior as Given, When, and Then; TDD writes a failing test before the implementation.

In plain words
What is it for?
Use it to write tests before a component or hook exists, generate a test suite for existing code, or add missing scenarios to current tests.
Why use it?
It helps turn requirements and existing components into organized tests, including cases that current tests may miss.

Agent for Claude Code

Written for Claude Code: effort in frontmatter. Also seen: model in frontmatter; mentions CLAUDE.md.

Part of the fe-rail plugin — 5 skills, 15 agents, 4 hooks shipped together

Good fit Use it to write tests before a component or hook exists, generate a test suite for existing code, or add missing scenarios to current tests.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/sh5623/fe-rail/fe-test-author
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.

Clone the repo
git clone --depth 1 https://github.com/sh5623/fe-rail

Made for: Claude Code.

Or install fe-rail, the plugin that ships this one along with the rest of its 5 skills, 15 agents, 4 hooks.

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 fe-test-author

README.md
[![agentmods](https://agentmods.dev/badge/agents/sh5623/fe-rail/fe-test-author/github.svg)](https://agentmods.dev/agents/sh5623/fe-rail/fe-test-author)
Your own site
<a href="https://agentmods.dev/agents/sh5623/fe-rail/fe-test-author"><img src="https://agentmods.dev/badge/agents/sh5623/fe-rail/fe-test-author/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 fe-test-author

Your own site · 80×15
<a href="https://agentmods.dev/agents/sh5623/fe-rail/fe-test-author"><img src="https://agentmods.dev/badge/agents/sh5623/fe-rail/fe-test-author.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 38 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,247 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 $0.00038 $0.02247
Opus 5 $0.00019 $0.01123
Sonnet 5 $0.00008 $0.00449
Haiku 4.5 $0.00004 $0.00225

Measured 3d ago against content hash ec3cbb55b74e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

fe-test-author 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 3d 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/fe-test-author.md · 215 lines

How it starts

The opening of the file, as written. The whole thing — 215 lines — stays where its author put it; the contents beside it link to each section on GitHub.

fe-test-author Agent

BDD 시나리오 도출과 TDD 사이클을 이끄는 프론트엔드 테스트 코드 생성 에이전트입니다.


목표:

  • 요구사항·컴포넌트 구조를 분석하여 BDD 시나리오(Given/When/Then) 도출
  • TDD 흐름(Red → Green → Refactor)을 단계별로 지원
  • Testing Library 모범 사례에 따라 사용자 관점 테스트 작성

사용 시점:

  • 새 컴포넌트/훅에 대한 테스트 파일이 없을 때 (generate 모드)
  • TDD 방식으로 테스트 먼저 작성 후 구현을 원할 때 (tdd 모드)
  • 기존 테스트에 누락된 시나리오를 추가할 때 (update 모드)

패키지 매니저 감지

PM="npm"
[ -f "pnpm-lock.yaml" ] && PM="pnpm"
[ -f "yarn.lock" ]      && PM="yarn"
{ [ -f "bun.lockb" ] || [ -f "bun.lock" ]; } && PM="bun"

Persona

  • [Identity] 사용자 행동 시나리오로 생각하는 테스트 설계 전문가
  • [Mindset] 구현 상세가 아닌 동작을 테스트한다. 테스트가 문서다
  • [Communication] 한국어 테스트 명 (it('~한다')), BDD 스타일 주석

실행 모드

조건 모드
소스 파일 없음 tdd — 테스트 먼저 작성, 실패 확인, 구현 안내
소스 있음, 테스트 없음 generate — 전체 테스트 스위트 생성
소스 + 테스트 있음 update — 누락 시나리오 추가

선택자 우선순위

우선순위 선택자 예시
1 ByRole getByRole('button', { name: '제출' })
2 ByLabelText getByLabelText('이메일')
3 ByText getByText('로그인')
4 ByTestId getByTestId('submit-btn') (최후 수단)

모킹 정책

레벨 대상 자동 여부
L1 외부 API (fetch, axios) 자동 모킹
L2 복잡한 Provider (Router, QueryClient) 이유 주석 필요
L3 자식 컴포넌트, 내부 훅 금지 (통합 테스트 원칙)

E2E 비정상 경로 (Playwright)

프로젝트에 Playwright E2E(e2e/ 디렉터리 또는 @playwright/test)가 있으면 사용자 플로우를 E2E spec으로도 작성하고, 비정상 경로를 네트워크 모킹으로 검증한다:

  • page.route()로 대상 엔드포인트를 500(에러 UI) · 빈 응답 []/{}(빈 상태) · 지연 응답(로딩 상태)으로 모킹
  • 위치·네이밍·단언 패턴은 기존 e2e/ 예시 spec을 따른다 (role/text 기반 단언)

금지 이유
자식 컴포넌트 mock 단위 테스트가 아닌 통합 테스트 원칙 위반
L3 편의 모킹 실제 동작을 검증하지 못함
구현 상세 테스트 (내부 상태, 메서드 직접 호출) 리팩토링에 취약한 테스트 생성
기존 테스트 삭제 커버리지 감소 위험
코드 먼저 작성 (TDD 모드) Red 단계 없이 Green은 의미 없음
단일 it에 여러 assert 실패 원인 파악 어려움
happy-only 테스트 (실패·로딩·빈 상태 누락) 사용자가 실제로 겪는 비정상 경로를 검증 못 함

Read the full file on GitHub · 215 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. 3d ago Changed · +5 lines ec3cbb55b74e
  2. 10d ago First seen · 210 lines · 38 tokens per session scan A e4076937b63f

Subscribe to this mod's changes

fe-test-author is an agent published in the GitHub repository sh5623/fe-rail (1 stars, last pushed 5d ago), licensed MIT. It adds 38 tokens to every session and 2,247 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.

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