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red-proof

Validates committed fixes by witnessing the new test fail against pre-fix code.

2|Updated Aug 2, 2026
Search Tags:#git#tdd#code review#regression testing#test validation#red-green#dotnet test
One-click install
npx skills add https://github.com/Arasz/ai-raccoon --skill red-proof-arasz
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: red-proof
Source: https://github.com/Arasz/ai-raccoon/tree/main/.ai-badger/skills/learned/software-development/red-proof
Command: npx skills add https://github.com/Arasz/ai-raccoon --skill red-proof-arasz

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve? When a fix is already committed — during PR review, after-the-fact test additions, or subagent output validation — a passing test alone cannot prove it actually covers the fixed behavior. This Skill enforces a witnessed RED run so the test is not indistinguishable from a tautology. ## Core Features & Use Cases - Pre-fix reconstruction: Locates the pre-fix version of a production file via git history (git log, git show) or by reverse-applying the fix diff. - Witnessed RED run: Temporarily restores the old code in a worktree, runs the new test expecting failure on the intended assertion, then restores HEAD and confirms with git status. - Evidence recording: Captures the pre-fix commit, expected-fail assertion, and post-fix pass count for the PR or review. - Use Case: While reviewing a fix PR, check out the pre-fix commit's version of the changed file, run the new test to watch it fail on the intended assertion, restore the fix, and document the RED/GREEN evidence in the review. ## Quick Start Use the red-proof skill to verify this committed fix by running its new test against the pre-fix code and recording the failure evidence.

Frequently Asked Questions about red-proof

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

FAQPage Schema
How do I verify a test actually covers a committed fix?▼

Check out the pre-fix version of the production file from git history, run the new test, and confirm it fails on the intended assertion. Then restore the fixed code with git checkout HEAD and verify the test passes.

How to find the pre-fix version of a file in git?▼

Use git log --oneline -- <file> to locate the commit before the fix commit, then git checkout <pre-fix-commit> -- <file> to restore that version. If the fix was squashed, inspect the diff with git show <fix-commit> -- <file>.

Why does a test pass on both old and new code?▼

A test passing on both versions never exercises the changed predicate, making it a silent no-op. The RED run against pre-fix code is the only proof the test actually covers the fixed behavior.

What if the new test does not compile against old code?▼

If the test references symbols added by the fix, the old-code build fails to compile. Write the assertion against the stable API surface, as a behavior test should, so it compiles against the pre-fix code.

Why run the whole test class after the RED check?▼

If you touched a shared fixture or constructor, every test in the class exercises that field. Running only the new test can miss regressions caused by fixture changes affecting other tests.

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