StrykerJS

Fork notice

This project is a fork of the corresponding @stryker-mutator package/repository. Maintenance here is intentionally limited, and this fork only exists while https://github.com/stryker-mutator/stryker-js/pull/5866 has not been accepted and implemented.

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 StrykerJS features, see stryker-mutator.io.

Getting started

Please follow the quickstart on the website.

For small js projects, you can try the following command:

npm install --save-dev @d-es-ign/stryker-js-core
# Only for small projects:
npx stryker run

It will run stryker with default values:

• Uses npm test as your test command
• Searches for files to mutate in the lib and src directories

Usage

$ npx stryker <command> [options] [configFile]

See usage on stryker-mutator.io

Supported mutators

See our website for the list of currently supported mutators.

Configuration

See configuration on stryker-mutator.io.

Mutation timing diagnostics

For mutation-phase diagnostics, enable the built-in mutation-timings reporter and set STRYKER_MUTATION_TEST_TIMINGS=1.

Example stryker.conf.json snippet:

{
  "reporters": ["progress", "clear-text", "mutation-timings"]
}

Environment variables:

• STRYKER_MUTATION_TEST_TIMINGS=1 enables per-mutant executedTests capture.
• STRYKER_MUTATION_TEST_TIMINGS_MAX_TESTS=<N> caps executedTests length per mutant.
• STRYKER_MUTATION_TEST_TIMINGS_FILE=<path> overrides sidecar output path (default: reports/mutation/mutant-test-timings.json).

Programmatic use

Stryker can also be used programmatically from nodejs. It exports 2 classes for you to use: Stryker and StrykerCli.

import { Stryker, StrykerCli } from '@d-es-ign/stryker-js-core';

Both classes can be used to run Stryker. The main difference is that Stryker is a slightly more low-level approach, while StrykerCli is the straight up CLI api.

In this example you can see how to use both.

async function main() {
  // Runs Stryker as if it was called directly from the cli. Not even returns a promise, it assumes to be allowed to call `process.exit`.
  new StrykerCli(process.argv /* RAW argv array */).run();

  // Runs Stryker, will not assume to be allowed to exit the process.
  const stryker = new Stryker(
    { concurrency: 4 } /* Partial Stryker options object */,
  );
  const mutantResults = await stryker.runMutationTest();
  // mutantResults or rejected with an error.
}

Stryker is written in TypeScript, so it is recommended to use Typescript as well to get the best developer experience.