heynest / stryker

The JavaScript mutation testing framework

Stryker

Professor X: For someone who hates mutants... you certainly keep some strange company.
William Stryker: Oh, they serve their purpose... as long as they can be controlled.

Introduction

For an introduction to mutation testing and Stryker's features, see stryker-mutator.github.io.

Getting started

Stryker is a mutation testing framework for JavaScript. It allows you to test your tests by temporarily inserting bugs.

To install Stryker, execute the command:

$ npm install stryker stryker-api --save-dev

Note: During installation you may run into errors caused by node-gyp. It is safe to ignore them.

To test if Stryker is installed correctly, execute the command:

$ node_modules/.bin/stryker --version

This should print the latest version of Stryker.

Usage

$ node_modules/.bin/stryker <command> [options] [stryker.conf.js]

The only command currently available is run, which kicks off mutation testing.

By default, we expect a stryker.conf.js file in the current working directory. This can be overridden by specifying a different file as the last parameter.

The following is an example stryker.conf.js file:

module.exports = function(config){
  config.set({
    files: ['test/helpers/**/*.js', 
            'test/unit/**/*.js', 
            { pattern: 'src/**/*.js', included: false, mutated: true }
            { pattern: 'src/templates/*.html', included: false, mutated: false }
            '!src/fileToIgnore.js'],
    testFramework: 'mocha',
    testRunner: 'mocha',
    reporter: ['progress', 'clear-text', 'dots', 'html', 'event-recorder'],
    coverageAnalysis: 'perTest',
    plugins: ['stryker-mocha-runner', 'stryker-html-reporter']
  });
}

As you can see, the config file is not a simple JSON file, it should be a common js (a.k.a. npm) module.
You might recognize this way of working from the karma test runner.

Make sure you at least specify the files and the testRunner options when mixing the config file and/or command line options.

Supported mutators

See our website for the list of currently supported mutators.

Configuration

See the stryker's package readme for all config options.