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---
name: property-based-test
description: |
Property-Based Testing（PBT）の自動設計・実装支援。テスト対象コードを静的分析し、
プロパティパターン選定・ジェネレータ合成・テストコード生成・実行・レポートを自動実行する。
フレームワーク自動検出。サブエージェント並列調査。
disable-model-invocation: true
argument-hint: "<target-path> [--focus <focus-area>]"
---
# Property-Based Testing Skill
## CONSTRAINT
```yaml
mode: write # テストコードを生成・実行する
source_modification: false # テスト対象のソースコードは変更しない
output_scope: test_files_only
```
## INPUT_SCHEMA
```yaml
arguments: "$ARGUMENTS"
parse_rules:
- pattern: "^(?<target_path>\\S+)(?:\\s+--focus\\s+(?<focus>.+))?$"
extract:
target_path: required # ファイルパス or モジュール名
focus: optional # カンマ区切りの重点観点
- pattern: "^$"
action: AskUserQuestion("テスト対象のファイルパスを指定してください")
focus_mapping:
"境界値|boundary": [invariant, metamorphic]
"エラー処理|error": [invariant, oracle]
"冪等性|idempotent": [idempotent]
"シリアライズ|serialize": [roundtrip]
"状態|state|stateful": [stateful]
"性能|performance": [oracle, metamorphic]
"代数|algebraic": [algebraic]
"全般|all": [ALL]
```
## EXECUTION_PIPELINE
```
Phase1:Analyze ──gate:data_ready──▶ Phase2:Design ──gate:plan_ready──▶ Phase3:Generate ──▶ Phase4:Execute ──▶ Phase5:Report
```
各 gate は前フェーズの出力が後フェーズの入力要件を満たすことを検証する内部チェック。ユーザー確認ゲートは不要（自動実行）。
---
## PHASE_1: ANALYZE
### 1.1 サブエージェント起動（並列）
```yaml
parallel_tasks:
- agent: Task(Explore)
id: agent_a
label: "対象コード静的分析"
prompt: |
{target_path} を読み込み、以下を構造化して返却せよ:
1. 全 public 関数/メソッドの一覧
各エントリ: {name, params: [{name, type, nullable, default}], return_type, is_pure, has_side_effects, mutates_state}
2. 関数ペア検出: {pairs: [{fn_a, fn_b, relation: "encode/decode"|"serialize/deserialize"|"to/from"|"write/read"}]}
3. 依存グラフ: {imports, internal_calls, external_calls}
4. 推定不変条件: [{function, invariant_description}]
- agent: Task(Explore)
id: agent_b
label: "テスト基盤調査"
prompt: |
プロジェクトルートから以下を特定せよ:
1. 言語: {lang: "typescript"|"python"|"rust"|"go"|"java"|"kotlin"|"ruby"}
2. テストFW: {test_framework, config_file, test_dir_pattern, test_file_pattern}
3. PBTライブラリ: {pbt_lib: string|null, version: string|null}
4. 既存テストスタイル: {sample_test_file, assertion_style, describe_pattern}
5. パッケージマネージャ: {manager, lockfile}
```
### 1.2 フレームワーク解決
```yaml
detection_rules:
typescript:
indicators: ["package.json", "tsconfig.json", ".ts files"]
test_fw_detect:
- {file: "jest.config.*", result: "jest"}
- {file: "vitest.config.*", result: "vitest"}
- {file: "package.json", key: "mocha", result: "mocha"}
pbt_lib_detect:
- {package: "fast-check", result: "fast-check"}
fallback_pbt: "fast-check"
install_cmd: "npm install --save-dev fast-check"
python:
indicators: ["setup.py", "pyproject.toml", "requirements*.txt", ".py files"]
test_fw_detect:
- {file: "pytest.ini|pyproject.toml[tool.pytest]|setup.cfg[tool:pytest]", result: "pytest"}
- {fallback: "unittest"}
pbt_lib_detect:
- {package: "hypothesis", result: "hypothesis"}
fallback_pbt: "hypothesis"
install_cmd: "pip install hypothesis"
rust:
indicators: ["Cargo.toml", ".rs files"]
test_fw_detect:
- {builtin: "cargo test", result: "cargo_test"}
pbt_lib_detect:
- {dep: "proptest", result: "proptest"}
fallback_pbt: "proptest"
install_cmd: 'Cargo.toml に追記: [dev-dependencies] proptest = "1"'
go:
indicators: ["go.mod", ".go files"]
test_fw_detect:
- {builtin: "go test", result: "go_test"}
pbt_lib_detect:
- {module: "pgregory.net/rapid", result: "rapid"}
fallback_pbt: "rapid"
install_cmd: "go get pgregory.net/rapid"
java:
indicators: ["pom.xml", "build.gradle", ".java files"]
test_fw_detect:
- {dep: "junit-jupiter", result: "junit5"}
pbt_lib_detect:
- {dep: "jqwik", result: "jqwik"}
fallback_pbt: "jqwik"
install_cmd: "pom.xml/build.gradle に jqwik 依存追加"
kotlin:
indicators: ["build.gradle.kts", ".kt files"]
test_fw_detect:
- {dep: "junit-jupiter|kotest", result: "junit5|kotest"}
pbt_lib_detect:
- {dep: "jqwik|kotest-property", result: "jqwik|kotest-property"}
fallback_pbt: "jqwik"
ruby:
indicators: ["Gemfile", ".rb files"]
test_fw_detect:
- {gem: "rspec", result: "rspec"}
- {fallback: "minitest"}
pbt_lib_detect:
- {gem: "rantly", result: "rantly"}
- {gem: "prop_check", result: "prop_check"}
fallback_pbt: "rantly"
install_cmd: "Gemfile に追記: gem 'rantly', group: :test"
```
### 1.3 PBTライブラリ未導入時
```
IF pbt_lib == null:
1. ユーザーに AskUserQuestion で確認:
"PBTライブラリ {fallback_pbt} が未導入です。インストールしますか？"
options: ["はい（推奨）", "いいえ（中断）"]
2. IF "はい": install_cmd を実行
3. IF "いいえ": 処理中断、理由を報告
```
### 1.4 Phase1 出力スキーマ
```yaml
# gate:data_ready の検証対象
phase1_output:
functions: [{name, params, return_type, is_pure, has_side_effects, mutates_state}]
function_pairs: [{fn_a, fn_b, relation}]
invariants: [{function, description}]
env:
lang: string
test_fw: string
pbt_lib: string
test_dir: string
test_file_pattern: string
assertion_style: string
focus_areas: string[] | null # --focus のパース結果
```
---
## PHASE_2: DESIGN
`references/property-patterns.md` のパターン選定アルゴリズムを適用する。
### 2.1 プロパティ選定アルゴリズム
```
FOR EACH function f IN phase1_output.functions:
candidates = []
# Rule 1: Round-trip
IF ∃ pair(f, g) IN function_pairs WHERE relation ∈ {"encode/decode", "serialize/deserialize", "to/from", "write/read"}:
candidates.append({pattern: "roundtrip", fn: [f, g], weight: 10})
# Rule 2: Invariant
IF f operates on collection OR f has output constraints:
FOR EACH inv IN known_invariants(f):
candidates.append({pattern: "invariant", fn: f, invariant: inv, weight: 8})
# Rule 3: Idempotent
IF f.return_type == f.params[0].type AND f.is_pure AND f.name matches /normalize|format|clean|trim|canonicalize|dedupe|sanitize/:
candidates.append({pattern: "idempotent", fn: f, weight: 7})
# Rule 4: Oracle
IF ∃ reference_impl(f) IN {stdlib, naive_impl, previous_version}:
candidates.append({pattern: "oracle", fn: f, oracle: reference_impl, weight: 9})
# Rule 5: Metamorphic
IF f is search/query/filter/sort/numeric_computation:
FOR EACH relation IN metamorphic_relations(f):
candidates.append({pattern: "metamorphic", fn: f, relation: relation, weight: 6})
# Rule 6: Algebraic
IF f is binary_operation AND (associative OR commutative OR has_identity):
FOR EACH law IN algebraic_laws(f):
candidates.append({pattern: "algebraic", fn: f, law: law, weight: 5})
# Rule 7: Stateful
IF f.mutates_state:
candidates.append({pattern: "stateful", fn: f, weight: 7})
# Focus boost
IF focus_areas != null:
FOR EACH c IN candidates:
IF c.pattern IN focus_mapping[focus_area]: c.weight += 5
# 選定: weight 降順、上位N個（N = min(candidates.length, 5)）
selected += candidates.sort_by(weight DESC).take(5)
```
### 2.2 プロパティ仕様の構造化
```yaml
# 各選定プロパティの出力フォーマット
property_spec:
id: "P{seq_number}"
pattern: "roundtrip|invariant|idempotent|oracle|metamorphic|algebraic|stateful"
target_functions: [string]
formal_definition: "∀ x ∈ Gen<T>: postcondition(x)"
precondition: "assume(x) 条件" | null
postcondition: "検証する不変条件"
generator_requirements:
input_types: [{param_name, type, constraints}]
edge_cases: [string]
expected_bug_class: "このプロパティが検出するバグの種類"
priority: integer # weight値
```
---
## PHASE_3: GENERATE
`references/generator-patterns.md` と `references/framework-templates.md` を参照。
### 3.1 ジェネレータ合成ルール
```
FOR EACH property IN selected_properties:
FOR EACH param IN property.generator_requirements.input_types:
generator = resolve_generator(param)
FUNCTION resolve_generator(param) -> GeneratorExpr:
MATCH param.type:
# プリミティブ型 → 組み込み
"integer" → gen.integer(param.constraints.min, param.constraints.max)
"float" → gen.float(param.constraints.min, param.constraints.max)
"string" → gen.string(param.constraints.minLen, param.constraints.maxLen)
"boolean" → gen.boolean()
# コレクション型 → 再帰合成
"Array<T>" → gen.array(resolve_generator(T), {minLength, maxLength})
"Map<K,V>" → gen.map(resolve_generator(K), resolve_generator(V))
"Set<T>" → gen.set(resolve_generator(T))
# nullable → oneOf合成
"T | null" → gen.oneOf(gen.constant(null), resolve_generator(T))
"T | undefined" → gen.option(resolve_generator(T))
# ドメイン型 → record合成
"Record{fields}" → gen.record({f.name: resolve_generator(f.type) for f in fields})
# Union型 → oneOf合成
"A | B | C" → gen.oneOf(resolve_generator(A), resolve_generator(B), resolve_generator(C))
# 列挙型 → constant選択
"Enum{values}" → gen.oneOf(...[gen.constant(v) for v in values])
# 依存型 → flatMap合成
"Dependent(a, f)" → resolve_generator(a).flatMap(a_val => f(a_val))
# エッジケース注入（frequency ラッピング）
WRAP WITH gen.frequency([
[75, base_generator],
[15, edge_case_generator(param.type)],
[10, extreme_value_generator(param.type)]
])
```
### 3.2 テストコード生成
```
PROCEDURE generate_test_code(properties, env):
template = load_template(env.lang, env.pbt_lib) # references/framework-templates.md
style = env.assertion_style
test_file_path = resolve_test_path(env.test_dir, env.test_file_pattern, target_path)
code_blocks = []
FOR EACH prop IN properties:
code_blocks.append(template.render(
property_spec=prop,
generators=prop.generators,
assertion_style=style
))
output_file = assemble(
imports=template.imports(env.pbt_lib, target_path),
body=code_blocks,
config={numRuns: 100, seed: null, timeout: env.timeout_ms}
)
WRITE output_file TO test_file_path
```
### 3.3 シュリンキング品質チェック
```yaml
shrinking_rules:
- rule: "filter の使用を検出した場合"
check: "フィルタ通過率 > 10% を推定"
fix: "map ベースの制約埋め込みに書き換え"
- rule: "ジェネレータ外での値変換を検出した場合"
fix: "map でジェネレータ内に移動"
- rule: "深い flatMap チェーンを検出した場合（depth > 3）"
fix: "依存を減らすか、中間構造を導入"
```
---
## PHASE_4: EXECUTE
```
PROCEDURE execute_tests(test_file_path, env):
cmd = MATCH env.lang:
"typescript" → "{npx|yarn} {jest|vitest} {test_file_path}"
"python" → "pytest {test_file_path} -v"
"rust" → "cargo test --test {test_name}"
"go" → "go test -run {test_func} -v {package}"
"java" → "mvn test -Dtest={test_class} | gradle test --tests {test_class}"
"ruby" → "bundle exec rspec {test_file_path}"
result = Bash(cmd)
IF result.exit_code != 0:
failures = parse_failures(result.output, env.pbt_lib)
FOR EACH failure IN failures:
analysis = classify_failure(failure)
# analysis.type ∈ {"true_bug", "false_positive", "generator_issue", "timeout"}
MATCH analysis.type:
"true_bug" → record_bug(failure.property, failure.counterexample, failure.shrunk_value)
"false_positive" → fix_property(failure.property), re-run
"generator_issue" → fix_generator(failure.generator), re-run
"timeout" → reduce_num_runs(failure.property), re-run
# re-run は最大2回まで
```
---
## PHASE_5: REPORT
```yaml
report_schema:
header:
target: "{target_path}"
lang: "{env.lang}"
test_fw: "{env.test_fw} + {env.pbt_lib}"
num_runs_per_property: integer
total_execution_time: string
properties:
- id: "P1"
pattern: string
target_function: string
formal_definition: string
result: "PASS|FAIL"
counterexample: object | null # FAIL時のみ
shrunk_value: object | null # FAIL時のみ
bugs_found:
- property_id: string
severity: "critical|major|minor"
description: string
counterexample: object
shrunk_to: object
suggested_fix: string | null
generator_notes:
- param: string
strategy: string
edge_cases_included: [string]
shrinking_status: "auto|custom|none"
recommendations:
- type: "additional_property|generator_extension|coverage_gap"
description: string
priority: "high|medium|low"
test_file: "{test_file_path}"
```
出力は上記スキーマに従った Markdown テーブル形式でユーザーに提示する。
---
## REFERENCE_FILES
```yaml
references:
- path: "references/property-patterns.md"
content: "7パターンの形式定義、適用述語、選定スコアリングルール"
- path: "references/generator-patterns.md"
content: "型代数に基づくジェネレータ合成規則、エッジケース分布仕様、シュリンキング不変条件"
- path: "references/framework-templates.md"
content: "6言語×PBTライブラリのコードテンプレート（検出ルール、import、assertion、config）"
```