crap4go

# 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: ```bash go run github.com/unclebob/crap4go/cmd/crap4go@latest ``` Or install it: ```bash go install github.com/unclebob/crap4go/cmd/crap4go@latest crap4go ``` ## Usage ```bash # Analyze all non-test Go source files under the module crap4go # Filter to specific path fragments 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 1. Deletes old coverage reports and runs Go coverage 2. Finds non-test `.go` files, excluding `.git`, `target`, and `vendor` 3. Extracts functions and methods with line ranges 4. Computes cyclomatic complexity (`if`, `for`, `range`, switch cases, select clauses, `&&`, `||`) 5. Reads Go coverage profile segments for per-function statement coverage 6. Applies CRAP formula: `CC² x (1 - cov)³ + CC` 7. Sorts by CRAP score descending and prints report