| name | crap4go |
| description | Use when the user asks for a CRAP report, cyclomatic complexity analysis, or code quality metrics on a Go project |
crap4go - CRAP Metric for Go
Computes the CRAP (Change Risk Anti-Pattern) score for every Go function and method. CRAP combines cyclomatic complexity with test coverage to identify functions that are both complex and under-tested.
Setup
Run from the root of a Go module:
go run github.com/unclebob/crap4go/cmd/crap4go@latest
Or install it:
go install github.com/unclebob/crap4go/cmd/crap4go@latest
crap4go
Usage
crap4go
crap4go internal/combat movement
crap4go automatically deletes old coverage reports, runs go test ./... -coverprofile=target/coverage/coverage.out, and then analyzes the results.
Output
A table sorted by CRAP score, worst first:
CRAP Report
===========
Function Package CC Cov% CRAP
-------------------------------------------------------------------------------------
Widget.Run widget 12 45.0% 130.2
simple widget 1 100.0% 1.0
Interpreting Scores
| CRAP Score | Meaning |
|---|
| 1-5 | Clean - low complexity, well tested |
| 5-30 | Moderate - consider refactoring or adding tests |
| 30+ | Crappy - high complexity with poor coverage |
How It Works
- Deletes old coverage reports and runs Go coverage
- Finds non-test
.go files, excluding .git, target, and vendor
- Extracts functions and methods with line ranges
- Computes cyclomatic complexity (
if, for, range, switch cases, select clauses, &&, ||)
- Reads Go coverage profile segments for per-function statement coverage
- Applies CRAP formula:
CC² x (1 - cov)³ + CC
- Sorts by CRAP score descending and prints report
