Bough

A polyglot incremental mutation tester.

Note

Beta software — functional and tested on Linux, macOS, and Windows, but the CLI and config format may still change before 1.0.

📖 Documentation

Features

• Incremental — mutation testing can take a long time. Bough stores all results to disk, so you can stop a run midway through and resume later. Check your mutation state into git and share coverage data across your team.
• Polyglot — built on tree-sitter, so adding new languages reuses most of the mutation testing machinery.
• Config, not plugins — no plugin ecosystem to navigate. A single config file controls everything: file globs, test commands, skip patterns via tree-sitter queries.

Installation

cargo install --locked --git https://github.com/CodeEnPlace/bough --bin bough

Or download a prebuilt binary from the latest release.

Quick Start

Create a bough.config.toml in your project root:

base_root_dir = "."
include = ["**/*"]
exclude = []

init.cmd = "npm install"
test.cmd = "npm run test"

[lang.js]
include = ["src/**/*.js"]
exclude = ["**/*.test.*"]

Then run:

bough show mutations  # see what bough will mutate
bough run             # run mutation testing
bough find            # find the most important missed mutations

See the tutorial for a full walkthrough.

Supported Languages

Language	ID
JavaScript	js
TypeScript	ts
Python	py
Rust	rs
Go	go
C	c
Java	java
C#	cs

Is your language not supported? Open an issue or PR on GitHub.

License

MIT