test-case-reducer

Reduce large failing test inputs to minimal forms using delta debugging.

1|2|Updated Mar 10, 2026

Search Tags:#testing #debugging #bug reproduction #fuzzing #delta debugging #test case reduction

Ready to run

npx skills add https://github.com/santosomar/general-secure-coding-agent-skills --skill test-case-reducer-santosomar

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: test-case-reducer
Source: https://github.com/santosomar/general-secure-coding-agent-skills/tree/main/skills/testing/test-case-reducer
Command: npx skills add https://github.com/santosomar/general-secure-coding-agent-skills --skill test-case-reducer-santosomar

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill drastically reduces the size of large, failing test inputs to their absolute minimum, making bugs easier to understand, debug, and fix.

Core Features & Use Cases

Delta Debugging: Applies general algorithms to find the smallest input that still triggers a specific failure.
Structured Shrinking: Optimizes reduction for known data formats like JSON or source code for faster, more relevant results.
Use Case: A fuzzer generates a 50KB input that crashes your parser. This Skill can reduce that input to a few bytes, revealing the exact data causing the crash.

Quick Start

Use the test-case-reducer skill to shrink the provided failing input file 'large_input.json' while preserving the 'KeyError: 'y'' failure.

Frequently Asked Questions about test-case-reducer

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I reduce a large fuzzer-generated input to a minimal test case?▼

To reduce a large fuzzer-generated input to a minimal test case, this Skill applies delta debugging and format-specific shrinking techniques to find the smallest input that still triggers the failure. This makes bugs easier to understand and fix.

What is delta debugging and how does it help with bug reproduction?▼

Delta debugging is a general algorithm used for bug reproduction that systematically reduces large failing test inputs to their absolute minimum. It ensures the reduced input still triggers the specific failure, making the root cause easier to isolate.

How do I shrink a failing JSON input while preserving a specific error?▼

To shrink a failing JSON input while preserving a specific error, the Skill uses structured shrinking optimized for known data formats alongside a deterministic 'interestingness' oracle function to verify failure preservation during the reduction process.

Do I need an interestingness oracle function to perform test case reduction?▼

Yes, you need a deterministic 'interestingness' oracle function to perform test case reduction. The oracle verifies that the failure is preserved during delta debugging and format-specific shrinking, ensuring the minimal input still triggers the exact bug.

Can I optimize regression test cases by shrinking large failing inputs?▼

You can optimize regression test cases by shrinking large failing inputs to their minimal reproducible form. The Skill reduces large bug reproduction cases and fuzzer-generated crashes to their absolute minimum, streamlining regression test optimization.

What are the limitations of using delta debugging for test case reduction?▼

A limitation of using delta debugging for test case reduction is the requirement for a deterministic 'interestingness' oracle function to verify failure preservation. Without a consistent oracle, the shrinking process cannot accurately validate minimized inputs.