edge-case-generator

edge-case-generator is a skill for Claude Code, Codex from ArabelaTso/Skills-4-SE. It costs 82 tokens per session (4,274 once invoked), scanned A, original, Apache-2.0.

A software-testing tool that looks for boundary conditions, unusual inputs, and failure situations, then suggests tests for them. It can cover unit, integration, property-based, mutation, and fuzz testing.

In plain words
What is it for?
Use it to analyze code, specifications, or APIs and create edge-case tests in common testing styles and programming languages.
Why use it?
It helps expose bugs that ordinary examples often miss, such as empty values, maximum limits, invalid state changes, resource exhaustion, and concurrency problems.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to analyze code, specifications, or APIs and create edge-case tests in common testing styles and programming languages.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/arabelatso/skills-4-se/edge-case-generator
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.

Any agent
npx skills add ArabelaTso/Skills-4-SE --skill edge-case-generator
Clone the repo
git clone --depth 1 https://github.com/ArabelaTso/Skills-4-SE

Made for: Claude Code, Codex.

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 edge-case-generator

README.md
[![agentmods](https://agentmods.dev/badge/skills/arabelatso/skills-4-se/edge-case-generator/github.svg)](https://agentmods.dev/skills/arabelatso/skills-4-se/edge-case-generator)
Your own site
<a href="https://agentmods.dev/skills/arabelatso/skills-4-se/edge-case-generator"><img src="https://agentmods.dev/badge/skills/arabelatso/skills-4-se/edge-case-generator/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 edge-case-generator

Your own site · 80×15
<a href="https://agentmods.dev/skills/arabelatso/skills-4-se/edge-case-generator"><img src="https://agentmods.dev/badge/skills/arabelatso/skills-4-se/edge-case-generator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 82 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,274 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 362
    Skill allows unbounded resource consumption (API calls, storage, compute). Without rate limits or quotas, a compromised or misbehaving agent can cause denial-of-service or cost overruns.
    Fix: Set explicit rate limits, timeouts, and resource quotas for API calls, file operations, and compute. Implement circuit breakers for runaway loops.
How audits are shown
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 $0.00082 $0.04274
Opus 5 $0.00041 $0.02137
Sonnet 5 $0.00016 $0.00855
Haiku 4.5 $0.00008 $0.00427

Measured 11d ago against content hash 97859a59537d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

edge-case-generator 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 11d 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/edge-case-generator/SKILL.md · 671 lines

How it starts

The opening of the file, as written. The whole thing — 671 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Edge Case Generator

Systematically identify boundary conditions, edge cases, and exceptional scenarios, then generate comprehensive tests to validate software behavior under uncommon conditions.

Core Capabilities

1. Edge Case Identification

Analyze code, specifications, or requirements to identify:

  • Boundary values: Min/max limits, zero, empty, first/last elements
  • Null and undefined: Missing data, null pointers, undefined references
  • Type boundaries: Integer overflow, floating-point precision, type mismatches
  • Collection edge cases: Empty collections, single element, duplicates
  • State transitions: Invalid state sequences, concurrent modifications
  • Resource limits: Memory exhaustion, timeout scenarios, disk full
  • Special characters: Unicode, whitespace, control characters
  • Concurrency issues: Race conditions, deadlocks, thread safety

2. Test Generation

Generate tests in multiple formats:

  • Unit tests (pytest, Jest, JUnit, Go testing, etc.)
  • Integration test scenarios
  • Property-based tests (Hypothesis, QuickCheck, fast-check)
  • Mutation testing scenarios
  • Fuzz testing inputs

3. Multi-Language Support

Support major programming languages:

  • Python, JavaScript/TypeScript, Java, C/C++, Go, Rust, C#, Ruby, PHP, Swift, Kotlin

Edge Case Analysis Workflow

Step 1: Identify Input Domains

Analyze each input parameter or data structure:

For numeric inputs:

- Minimum value (e.g., INT_MIN, 0, -∞)
- Maximum value (e.g., INT_MAX, 255, +∞)
- Zero
- One (unit value)
- Negative one
- Just below/above boundaries
- Overflow/underflow values

For collections (arrays, lists, sets):

- Empty collection
- Single element
- Two elements (minimal interaction)
- Maximum size (if bounded)
- All identical elements
- All unique elements
- Sorted vs unsorted
- Contains duplicates

For strings:

- Empty string ("")
- Single character
- Very long string (10K+ chars)
- Unicode characters (emoji, RTL, special)
- Whitespace only ("   ")
- Null terminator issues
- Special characters (\n, \t, \0)

Read the full file on GitHub · 671 lines

Files

What ships with it

4 files 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. 11d ago First seen · 671 lines · 82 tokens per session scan A 97859a59537d

Subscribe to this mod's changes

edge-case-generator is a skill published in the GitHub repository ArabelaTso/Skills-4-SE (251 stars, last pushed 20d ago), licensed Apache-2.0. It adds 82 tokens to every session and 4,274 once invoked, about $0.0004 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 2026-08-30.

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