| name | bug-magnet-data |
| description | Curated edge case test data for boundary testing, verification scripts, and test generation. Provides pre-curated reference data organized by data type with context-specific loading guidance. |
| user-invocable | false |
Bug Magnet Data
Curated edge case test data for boundary testing, verification scripts, and test generation. 50+ years of testing wisdom distilled into small, high-signal collections organized by data type.
Core Principle: Curation beats generation. 50 well-chosen edge cases find more bugs than 10,000 random inputs.
When to Use This Skill
Load this skill when the consumer request matches ANY of these patterns:
| Consumer | Trigger | Usage |
|---|
| test-audit | Step 7 (edge case gap detection) | Identify missing boundary test coverage |
| bulwark-verify | Generating verification scripts | Inject edge cases into test scenarios |
| bulwark-fix-validator | Validating a fix | Test fix against boundary conditions |
DO NOT use for:
- Encrypted/compressed data (edge cases won't penetrate wrapping)
- Pure unit tests with fully mocked dependencies (edge cases need real execution)
- Performance/load testing (use dedicated load testing tools)
Pre-Flight Gate (BLOCKING)
STOP. Before providing ANY edge case data, you MUST follow the three-phase workflow.
This skill provides curated data through a deterministic workflow. You must execute all phases.
What You MUST Do
- Phase 1: Component Detection - Identify component type and load context file
- Phase 2: Data Loading - Load T0 + T1 data files (REQUIRED), T2 if specified by context
- Phase 3: Edge Case Application - Apply edge cases and report what was loaded
What You MUST NOT Do
- Do NOT generate edge cases from your own knowledge - use the curated data files
- Do NOT skip loading context files - they determine which categories apply
- Do NOT skip the safety filter - patterns marked
safe_for_automation: false must be excluded
- Do NOT return partial data - all applicable tiers must be loaded
Why This Matters
The curated data exists because:
- Curation beats generation - 50 well-chosen edge cases find more bugs than 10,000 random inputs
- Reproducibility - Same component type = same edge cases every time
- Safety - Destructive patterns are explicitly marked and filtered
If you find yourself thinking "I know some good edge cases" - STOP. Use the data files.
Completion Checklist
Before returning to consumer, verify ALL items:
Do NOT return to consumer until all checkboxes can be marked complete.
Dependencies
This skill provides data files and context guidance. Understanding what to load ensures deterministic execution.
| Category | Files | Requirement | When to Load |
|---|
| Context files | context/{component-type}.md | REQUIRED | Always load for detected component type |
| T0 data (boundaries) | data/strings/boundaries.yaml, data/numbers/boundaries.yaml, data/booleans/boundaries.yaml, data/collections/arrays.yaml | REQUIRED | Every edge case injection |
| T1 data (common) | data/strings/unicode.yaml, data/strings/special-chars.yaml, data/strings/injection.yaml, data/numbers/special.yaml | REQUIRED | Most edge case injections |
| T2 data (context-specific) | data/dates/*.yaml, data/encoding/*.yaml, data/formats/*.yaml, data/concurrency/*.yaml | CONDITIONALLY REQUIRED | If context file specifies → MUST load |
| Language-specific | data/language-specific/{language}.yaml | CONDITIONALLY REQUIRED | If testing language-specific behavior → MUST load |
| External references | references/external-lists.md | REQUIRED | For source attribution and update checking |
Fallback behavior:
- If component type detected → Loading
context/{type}.md is REQUIRED
- If context file specifies a category → Loading that category is REQUIRED
- If a referenced file is missing → Note in output, continue with available data
Data Tiers
| Tier | Categories | When to Load |
|---|
| T0 (Always) | Boundaries (empty/single/max), Null handling | Every edge case injection |
| T1 (Common) | Basic injection, Unicode basics, Numeric edges | Every edge case injection |
| T2 (Context) | Date/time, Encoding, Formats, Concurrency | When context file specifies |
| T3 (Manual) | Patterns marked manual_only: true | NEVER for automated runs |
Safety Filtering: Patterns with safe_for_automation: false or manual_only: true MUST be excluded from automated test runs.
Three-Phase Workflow
CRITICAL: All three phases are REQUIRED. Do not skip any phase.
Phase 1: Component Detection (Deterministic)
├── Identify component type from code under test
├── Map to context file: context/{cli-args|http-body|file-contents|db-query|process-spawn}.md
└── Load context file → get applicable categories list
Phase 2: Data Loading (Deterministic)
├── Load T0 data files (REQUIRED - always)
├── Load T1 data files (REQUIRED - always)
├── Load T2 data files specified by context file (CONDITIONALLY REQUIRED)
├── Load language-specific file if applicable (CONDITIONALLY REQUIRED)
└── Apply safety filter: exclude patterns with safe_for_automation: false
Phase 3: Edge Case Application
├── Inject loaded edge cases into test scenarios
├── Report which categories were loaded
└── Report any patterns excluded due to safety filtering
Component Type Detection
Map code under test to component type. Detection determines which context file to load.
| Code Pattern | Component Type | Context File |
|---|
| CLI argument parsing, process.argv, argparse | CLI | context/cli-args.md |
| HTTP request/response, req.body, fetch, axios | HTTP | context/http-body.md |
| File I/O, fs.read, open(), file parsing | File | context/file-contents.md |
| Database queries, SQL, ORM operations | Database | context/db-query.md |
| Child process, spawn, exec, subprocess | Process | context/process-spawn.md |
If multiple types apply: Load context files for each applicable type.
Category Reference
Strings (T0/T1)
| File | Contents | Bugs Caught |
|---|
strings/boundaries.yaml | Empty, single char, long strings, whitespace | NullPointerException, buffer overflow, off-by-one |
strings/unicode.yaml | Multi-byte, normalization, emoji, RTL | Encoding errors, length calculation bugs |
strings/special-chars.yaml | Quotes, escapes, control characters | Escape sequence handling, delimiter confusion |
strings/injection.yaml | SQL, XSS, command injection, path traversal | Security vulnerabilities |
Numbers (T0/T1)
| File | Contents | Bugs Caught |
|---|
numbers/boundaries.yaml | 0, -1, 1, MAX_INT, MIN_INT | Integer overflow/underflow, off-by-one |
numbers/special.yaml | NaN, Infinity, -0 | Special value handling, NaN propagation |
numbers/precision.yaml | 0.1+0.2, large/small floats | Floating point comparison failures |
Booleans (T0)
| File | Contents | Bugs Caught |
|---|
booleans/boundaries.yaml | true, false, null, truthy/falsy | Null reference, truthy/falsy confusion |
Collections (T0)
| File | Contents | Bugs Caught |
|---|
collections/arrays.yaml | Empty, single, large, nested, sparse | Index out of bounds, empty collection crashes |
collections/objects.yaml | Empty, nested, circular, prototype pollution | Null reference, prototype pollution |
Dates (T2)
| File | Contents | Bugs Caught |
|---|
dates/boundaries.yaml | Epoch, Y2K38, leap year | Y2K38 overflow, leap year bugs |
dates/timezone.yaml | DST transitions, UTC offsets | DST errors, timezone conversion |
dates/invalid.yaml | Feb 30, invalid formats | Date parsing failures |
Encoding (T2)
| File | Contents | Bugs Caught |
|---|
encoding/charset.yaml | ASCII, UTF-8, BOM | Encoding detection, mojibake |
encoding/normalization.yaml | NFC, NFD, overlong | Normalization mismatches |
Formats (T2)
| File | Contents | Bugs Caught |
|---|
formats/email.yaml | Valid/invalid patterns | Overly strict/lenient validation |
formats/url.yaml | Valid/invalid patterns | URL parsing errors |
formats/json.yaml | Valid/invalid patterns | JSON parsing errors |
Concurrency (T2)
| File | Contents | Bugs Caught |
|---|
concurrency/race-conditions.yaml | Double submit, concurrent edit | Race conditions, lost updates |
concurrency/state-machines.yaml | Invalid transitions | State corruption |
Language-Specific (Conditional)
| File | Contents | Bugs Caught |
|---|
language-specific/javascript.yaml | == vs ===, truthy/falsy | Type coercion bugs |
language-specific/python.yaml | None vs False, mutable defaults | Python-specific gotchas |
language-specific/rust.yaml | Ownership, borrowing | Memory safety issues |
Data File Format
All data files use this YAML structure:
metadata:
version: "1.0.0"
last_updated: "2026-02-01"
source_urls: []
category: strings
subcategory: boundaries
tier: T0
values:
identifier:
value: "actual value"
bugs_caught: ["Bug type 1", "Bug type 2"]
safe_for_automation: true
manual_only: false
Safety flags to check:
safe_for_automation: false → Exclude from automated runsmanual_only: true → NEVER include in automated runs
Integration Examples
test-audit (Step 7)
1. Detect component type from test file
2. Load context file for component type
3. Load T0 + T1 data files
4. Load T2 files specified by context
5. Compare test coverage against loaded edge cases
6. Report missing edge case coverage
bulwark-verify
1. Detect component type from code under verification
2. Load context file for component type
3. Load T0 + T1 data files
4. Load T2 files specified by context
5. Filter out patterns with safe_for_automation: false
6. Inject applicable edge cases into verification script
bulwark-fix-validator
1. Detect component type from fix
2. Load context file for component type
3. Load T0 + T1 data files
4. Test fix against loaded edge cases
5. Report any edge cases that break the fix
