crap-analysis

1# CRAP Score Analysis
2 
3## When to Use This Skill
4 
5Use this skill when:
6- Evaluating code quality and test coverage before changes
7- Identifying high-risk code that needs refactoring or testing
8- Setting up coverage collection for a .NET project
9- Prioritizing which code to test based on risk
10- Establishing coverage thresholds for CI/CD pipelines
11 
12---
13 
14## What is CRAP?
15 
16**CRAP Score = Complexity x (1 - Coverage)^2**
17 
18The CRAP (Change Risk Anti-Patterns) score combines cyclomatic complexity with test coverage to identify risky code.
19 
20| CRAP Score | Risk Level | Action Required |
21|------------|------------|-----------------|
22| **< 5** | Low | Well-tested, maintainable code |
23| **5-30** | Medium | Acceptable but watch complexity |
24| **> 30** | High | Needs tests or refactoring |
25 
26### Why CRAP Matters
27 
28- **High complexity + low coverage = danger**: Code that's hard to understand AND untested is risky to modify
29- **Complexity alone isn't enough**: A complex method with 100% coverage is safer than a simple method with 0%
30- **Focuses effort**: Prioritize testing on complex code, not simple getters/setters
31 
32### CRAP Score Examples
33 
34| Method | Complexity | Coverage | Calculation | CRAP |
35|--------|------------|----------|-------------|------|
36| `GetUserId()` | 1 | 0% | 1 x (1 - 0)^2 | **1** |
37| `ParseToken()` | 54 | 52% | 54 x (1 - 0.52)^2 | **12.4** |
38| `ValidateForm()` | 20 | 0% | 20 x (1 - 0)^2 | **20** |
39| `ProcessOrder()` | 45 | 20% | 45 x (1 - 0.20)^2 | **28.8** |
40…