name: ring:dev-fuzz-testing title: Development cycle fuzz testing (Gate 4) category: development-cycle tier: 1 when_to_use: | Use after unit testing (Gate 3) is complete. MANDATORY for all development tasks - discovers edge cases and crashes. description: | Gate 4 of development cycle - ensures fuzz tests exist with proper seed corpus to discover edge cases, crashes, and unexpected input handling. trigger: | - After unit testing complete (Gate 3) - MANDATORY for all development tasks - Discovers crashes and edge cases via random input generation NOT_skip_when: | - "Unit tests cover edge cases" - Fuzz tests find cases you didn't think of. - "No time for fuzz testing" - Fuzz tests catch crashes before production. - "Code is simple" - Simple code can still crash on unexpected input. sequence: after: [ring:dev-unit-testing] before: [ring:dev-property-testing] related: complementary: [ring:dev-cycle, ring:dev-unit-testing, ring:qa-analyst] input_schema: required: - name: unit_id type: string description: "Task or subtask identifier" - name: implementation_files type: array items: string description: "Files from Gate 0 implementation" - name: language type: string enum: [go] description: "Programming language (Go only for native fuzz)" optional: - name: gate3_handoff type: object description: "Full handoff from Gate 3 (unit testing)" output_schema: format: markdown required_sections: - name: "Fuzz Testing Summary" pattern: "^## Fuzz Testing Summary" required: true - name: "Corpus Report" pattern: "^## Corpus Report" required: true - name: "Handoff to Next Gate" pattern: "^## Handoff to Next Gate" required: true metrics: - name: result type: enum values: [PASS, FAIL] - name: fuzz_functions type: integer - name: corpus_entries type: integer - name: crashes_found type: integer - name: iterations type: integer verification: automated: - command: "grep -rn 'func Fuzz' --include='*_test.go' ." description: "Fuzz functions exist" success_pattern: "func Fuzz" - command: "grep -rn 'f.Add' --include='*_test.go' ." description: "Seed corpus entries exist" success_pattern: "f.Add" manual: - "Fuzz functions follow FuzzXxx naming convention" - "Seed corpus has at least 5 entries per function" - "No crashes found during 30s fuzz run" examples: - name: "Fuzz tests for parser" input: unit_id: "task-001" implementation_files: ["internal/parser/json.go"] language: "go" expected_output: | ## Fuzz Testing Summary **Status:** PASS **Fuzz Functions:** 2 **Corpus Entries:** 12 **Crashes Found:** 0 ## Corpus Report | Function | Entries | Crashes | |

-------|---------|---------| | FuzzParseJSON | 6 | 0 | | FuzzParseConfig | 6 | 0 |

code

  ## Handoff to Next Gate
  - Ready for Gate 5 (Property Testing): YES

Dev Fuzz Testing (Gate 4)

Name: ring:dev-fuzz-testing
Rating: 92
Author: LerianStudio

Overview

Ensure critical parsing and input handling code has fuzz tests to discover crashes and edge cases through random input generation.

Core principle: Fuzz tests find bugs you didn't think to test for. They're mandatory for all code that handles external input.

<block_condition>

•No fuzz functions = FAIL
•Seed corpus < 5 entries = FAIL
•Any crash found = FAIL (fix and re-run) </block_condition>

CRITICAL: Role Clarification

This skill ORCHESTRATES. QA Analyst Agent (fuzz mode) EXECUTES.

Who	Responsibility
This Skill	Gather requirements, dispatch agent, track iterations
QA Analyst Agent	Write fuzz tests, generate corpus, run fuzz

Standards Reference

MANDATORY: Load testing-fuzz.md standards via WebFetch.

<fetch_required> https://raw.githubusercontent.com/LerianStudio/ring/main/dev-team/docs/standards/golang/testing-fuzz.md </fetch_required>

Step 1: Validate Input

text

REQUIRED INPUT:
- unit_id: [task/subtask being tested]
- implementation_files: [files from Gate 0]
- language: [go only for native fuzz]

OPTIONAL INPUT:
- gate3_handoff: [full Gate 3 output]

if any REQUIRED input is missing:
  → STOP and report: "Missing required input: [field]"

if language != "go":
  → STOP and report: "Native fuzz testing only supported for Go (Go 1.18+)"

Step 2: Dispatch QA Analyst Agent (Fuzz Mode)

text

Task tool:
  subagent_type: "ring:qa-analyst"
  model: "opus"
  prompt: |
    **MODE:** FUZZ TESTING (Gate 4)

    **Standards:** Load testing-fuzz.md

    **Input:**
    - Unit ID: {unit_id}
    - Implementation Files: {implementation_files}
    - Language: {language}

    **Requirements:**
    1. Create fuzz functions (FuzzXxx naming)
    2. Add seed corpus (minimum 5 entries per function)
    3. Run fuzz tests for 30 seconds
    4. Report any crashes found

    **Output Sections Required:**
    - ## Fuzz Testing Summary
    - ## Corpus Report
    - ## Handoff to Next Gate

Step 3: Evaluate Results

text

Parse agent output:

if "Status: PASS" in output:
  → Gate 4 PASSED
  → Return success with metrics

if "Status: FAIL" in output:
  → Dispatch fix to implementation agent
  → Re-run fuzz tests (max 3 iterations)
  → If still failing: ESCALATE to user

Step 4: Generate Output

text

## Fuzz Testing Summary
**Status:** {PASS|FAIL}
**Fuzz Functions:** {count}
**Corpus Entries:** {count}
**Crashes Found:** {count}

## Corpus Report
| Function | Entries | Crashes |
|----------|---------|---------|
| {function_name} | {count} | {count} |

## Handoff to Next Gate
- Ready for Gate 5 (Property Testing): {YES|NO}
- Iterations: {count}

Anti-Rationalization Table

Rationalization	Why It's WRONG	Required Action
"Unit tests cover edge cases"	You can't test what you don't think of. Fuzz finds unknowns.	Write fuzz tests
"Code is too simple for fuzz"	Simple code can still crash on malformed input.	Write fuzz tests
"Fuzz testing is slow"	30 seconds per function. Crashes in production are slower.	Write fuzz tests
"We validate input anyway"	Validation can have bugs too. Fuzz tests the validators.	Write fuzz tests