generate-tests

generate-tests is a skill for Claude Code from kotaroyamame/formal-agent-contracts. It costs 186 tokens per session (8,457 once invoked), scanned A, original, MIT.

A test-generation skill that turns VDM-SL specifications and protocol documents into Jest- or Vitest-compatible contract tests. VDM-SL is a formal language for describing software rules; contract tests check that code follows those rules.

In plain words
What is it for?
Use it to generate tests for VDM-SL invariants, preconditions, postconditions, edge values, message formats, state changes, and API signatures.
Why use it?
It reduces the manual work of translating type constraints, input and output conditions, protocol rules, and boundary cases into tests.

Skill for Claude Code

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

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is files: ./coverage/lcov.info.

Part of the formal-agent-contracts plugin — 15 skills shipped together

Good fit Use it to generate tests for VDM-SL invariants, preconditions, postconditions, edge values, message formats, state changes, and API signatures.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/kotaroyamame/formal-agent-contracts
agentmods
npx agentmods add skills/kotaroyamame/formal-agent-contracts/generate-tests

Made for: Claude Code.

Or install formal-agent-contracts, the plugin that ships this one along with the rest of its 15 skills.

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 generate-tests

README.md
[![agentmods](https://agentmods.dev/badge/skills/kotaroyamame/formal-agent-contracts/generate-tests/github.svg)](https://agentmods.dev/skills/kotaroyamame/formal-agent-contracts/generate-tests)
Your own site
<a href="https://agentmods.dev/skills/kotaroyamame/formal-agent-contracts/generate-tests"><img src="https://agentmods.dev/badge/skills/kotaroyamame/formal-agent-contracts/generate-tests/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 generate-tests

Your own site · 80×15
<a href="https://agentmods.dev/skills/kotaroyamame/formal-agent-contracts/generate-tests"><img src="https://agentmods.dev/badge/skills/kotaroyamame/formal-agent-contracts/generate-tests.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 186 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 8,457 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 $0.00186 $0.08457
Opus 5 $0.00093 $0.04228
Sonnet 5 $0.00037 $0.01691
Haiku 4.5 $0.00019 $0.00846

Measured 12d ago against content hash ed6057dae309, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

generate-tests 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 12d 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/generate-tests/SKILL.md · 854 lines

How it starts

The opening of the file, as written. The whole thing — 854 lines — stays where its author put it; the contents beside it link to each section on GitHub.

契約テスト自動生成スキル (v2.1.0)

VDM-SL形式仕様および設計文書から自動的にユニットテストコードを生成するスキルです。VDM-SL仕様に記述された型不変式、前提条件、後提条件と、設計文書(PROTOCOL.md、API-SIGNATURES.md)に記述されたプロトコル規則をテストコードに変換し、実装の正確性を検証します。

背景:VDM-SL仕様と設計文書の役割分担

エージェント開発は2つのフェーズで契約を定義します:

フェーズ 役割 成果物 このスキルでの使用
Phase 1:ドメイン設計 各エージェント内部のロジックを形式化 VDM-SL仕様ファイル 型不変式、前後提条件テスト生成
Phase 2:インターフェース設計 エージェント間通信を定義 PROTOCOL.md、API-SIGNATURES.md プロトコルテスト生成

実装時に発生する可能性のある問題と検出方法

問題カテゴリ 検出方法
実装バグ(ドメイン層) 後提条件のロジック誤り ✓ VDM-SLテストで検出
言語固有の問題 JavaScriptの型強制、nullの扱い ✓ VDM-SLテストで検出
プロトコル層バグ メッセージ型とペイロードの不整合 ✓ 設計文書テストで検出
エッジケース 境界値での動作未定義 ✓ VDM-SLテストで検出
並行処理の問題 レースコンディション(複数エージェント) 統合テストで検出

このスキルは以下の2つのソースから自動テスト生成します:

VDM-SL仕様から生成:

  1. 型不変式テスト:型の制約が常に満たされるか
  2. 前提条件テスト:関数が前提条件を期待通り検証するか
  3. 後提条件テスト:関数が後提条件を満たす結果を返すか
  4. 境界値テスト:エッジケースでの動作

設計文書(PROTOCOL.md)から生成: 5. プロトコルテスト(新v2.0.0):メッセージの型安全性、状態遷移の正確性、API署名の一貫性

ステップ1:VDM-SLファイルと設計文書の解析

目的:VDM-SLファイルと設計文書から型、関数、契約、プロトコル仕様を抽出

ユーザーに以下の情報を提供してもらいます:

  • VDM-SLファイル:解析対象のファイルパス
  • 設計文書:PROTOCOL.md、API-SIGNATURES.md(プロトコルテスト対象)
  • テスト対象関数:全関数 / 特定関数のみ
  • テスト対象言語:JavaScript / TypeScript / その他
  • テストフレームワーク:Vitest(推奨) / Jest / Mocha

スキルの処理

ステップ1a: VDM-SLファイルの構文解析
  ✓ モジュール構造を抽出
  ✓ 型定義を解析
  ✓ 関数シグネチャを抽出

ステップ1b: 契約情報の抽出
  ✓ 前提条件(pre)を読み込み
  ✓ 後提条件(post)を読み込み
  ✓ 不変式(inv)を収集

ステップ1c: メタデータの生成
  ✓ 関数の入出力型を記録
  ✓ テスト生成戦略を決定
  ✓ テストケース数を見積もり

出力例:
  [解析結果サマリー]
  ファイル: HybridJudgeAgent.vdmsl
  検出された型: 6個
    - Score (nat1, inv: 1<=s<=100)
    - Threshold (nat1, inv: 1<=t<=100)
    - Action (Quote型)
    - Ticket (Record型)
    - ...
  
  検出された関数: 3個
    - decide(Ticket, Score, Score) -> Action
    - scoreAll(seq of Score) -> seq of Score
    - explain_decision(...) -> seq of char
  
  推定テストケース数: 25-35個

ステップ1.5:モデルルーティングの確認(任意・トークン削減)

仕様ファイルの隣に model-routing.jsonroute-models スキルの成果物)が存在する場合:

Read the full file on GitHub · 854 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. 12d ago First seen · 854 lines · 186 tokens per session scan A ed6057dae309

Subscribe to this mod's changes

generate-tests is a skill published in the GitHub repository kotaroyamame/formal-agent-contracts (1 stars, last pushed 2mo ago), licensed MIT. It adds 186 tokens to every session and 8,457 once invoked, about $0.0009 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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