Crap Analysis

This walks you through setting up CRAP score analysis for .NET projects, which combines cyclomatic complexity with test coverage to find risky code (the formula is complexity times one minus coverage squared). The guide is thorough on the mechanics: you need OpenCover format specifically because it includes complexity metrics, ReportGenerator to build the HTML reports, and a proper runsettings file to exclude generated code and test assemblies. The Risk Hotspots section in the output is what you're after, showing methods with high complexity and low coverage that are dangerous to touch. Useful if you're inheriting a codebase or need to justify where testing effort should go. The threshold recommendations are reasonable: CRAP scores over 30 need immediate attention.

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last updated: Aug 21, 2026

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Install

$ npx -y skills add aaronontheweb/dotnet-skills --skill crap-analysis --agent claude-code

Installs into .claude/skills of the current project.

Files

CRAP Score Analysis

When to Use This Skill

Use this skill when:

Evaluating code quality and test coverage before changes
Identifying high-risk code that needs refactoring or testing
Setting up coverage collection for a .NET project
Prioritizing which code to test based on risk
Establishing coverage thresholds for CI/CD pipelines

What is CRAP?

CRAP Score = Complexity x (1 - Coverage)^2

The CRAP (Change Risk Anti-Patterns) score combines cyclomatic complexity with test coverage to identify risky code.

CRAP Score	Risk Level	Action Required
< 5	Low	Well-tested, maintainable code
5-30	Medium	Acceptable but watch complexity
> 30	High	Needs tests or refactoring

Why CRAP Matters

High complexity + low coverage = danger: Code that's hard to understand AND untested is risky to modify
Complexity alone isn't enough: A complex method with 100% coverage is safer than a simple method with 0%
Focuses effort: Prioritize testing on complex code, not simple getters/setters