summary: "Package README for crap4ts, the TypeScript/JavaScript CRAP metric tool." read_when:

• "You are using crap4ts from the monorepo"
• "You need package-level CLI behavior or output semantics" type: "reference"

crap4ts

Published as @tryinget/crap4ts.

A TypeScript/JavaScript CRAP metric calculator built on the TypeScript compiler API. crap4ts can be used standalone for hotspot ranking, but it is also the intended companion package for @tryinget/ts-mutate. The repo keeps them as separate packages so teams can adopt hotspot analysis without pulling in mutation testing, while the quality receipt still lets them operate hand in hand.

Features

• Parses .ts, .tsx, .js, .jsx
• Extracts named functions and methods with file and line span
• Computes cyclomatic complexity per function
• Parses LCOV (lcov.info)
• Maps line coverage back to function ranges
• Calculates CRAP scores
• Sorts output by highest CRAP first
• Supports path-fragment filtering

Usage

npm exec --yes --package @tryinget/crap4ts -- crap4ts
npm exec --yes --package @tryinget/crap4ts -- crap4ts --src src --lcov coverage/lcov.info
npm exec --yes --package @tryinget/crap4ts -- crap4ts --src src --filter auth/
npm exec --yes --package @tryinget/crap4ts -- crap4ts --json

Coverage-aware workflow

Generate source-mapped LCOV from the package test suite:

npm run coverage --workspace packages/crap4ts

Then run crap4ts against the package-local LCOV:

npm exec --workspace packages/crap4ts -- crap4ts --cwd packages/crap4ts
npm exec --workspace packages/crap4ts -- crap4ts --cwd packages/crap4ts --lcov coverage/lcov.info --json

For a repo-level hotspot receipt that also prints the next ts-mutate command, run:

just quality crap4ts

# npm equivalent
npm run quality -- --package crap4ts

That is the intended companion workflow: use crap4ts to rank hotspots, then hand the suggested file to ts-mutate.

CLI options

• --src <path>: source root or file. Repeatable. Defaults to src
• --lcov <path>: explicit LCOV file. If omitted, the tool tries coverage/lcov.info, target/coverage/lcov.info, then lcov.info
• --filter <fragment>: path fragment filter. Repeatable
• --json: machine-readable output
• --cwd <path>: override working directory
• --help: print usage

Output columns

• Function: inferred function or method name
• File: path relative to the working directory
• Lines: start-end line span
• CC: cyclomatic complexity
• Cov%: line coverage percent from LCOV
• CRAP: calculated CRAP score