karma test runner example (with webpack)

karma.config.js

var webpackConfig = require('./webpack.config')
webpackConfig.entry = undefined

module.exports = function (config) {
  config.set({
    browsers: ['Chrome'],
    files: [
      'tests.webpack.js' // karma only needs to know where test files are. if you include source files, you are gonna have a bad time.
    ],
    frameworks: ['mocha'],
    preprocessors: {
      'tests.webpack.js': ['webpack']
    },
    reporters: ['progress'],
    singleRun: true,
    webpack: webpackConfig,
    webpackMiddleware: {
      noInfo: true,
    }
  });
};

tests.webpack.js

// tells karma where test files are located
// test files live in src and end with .spec.js
var testsContext = require.context("./src", true, /\.spec\.js$/);
testsContext.keys().forEach(testsContext);