Parallel-test-runner NPM

parallel-test-runner

Run your Mocha tests faster

parallel-test-runner is a parallel test runner for Mocha. It runs your test files on several node processes, and does not require making any changes to your existing tests. I was able to obtain a 2-3x speed increase in running time for my existing projects by using this package, which is pretty cool.

Installation

$ npm i -S parallel-test-runner

Usage

Create a new runner file:

parallelTestRunner.js:

#!/usr/bin/env node

const {runner} = require('parallel-test-runner');
const path = require('path');

runner()
    .config({
        pattern: 'test/**/*.test.js', //mandatory
        shuffleFiles: false, //optional
        slowTestPatterns: ['SlowTestFilePattern.js'], //optional
        requireFiles: [path.resolve(__dirname, '../test/setup.js')], //optional
        parallelFactor: 4 //The number of processes the test runner will spawn
    })
    .run()
    .then(() => {
        process.exit(0);
    })
    .catch(() => {
        process.exit(1);
    });

Now you can simply execute ./parallelTestRunner.js to run your tests.

Flaky tests

Running the tests in parallel might cause some of them to fail randomly. This is probably because you have concurrency issues in your tests or production code. You can try including them in the slowTestPatterns, which will run them in a separate process.