karma.conf.js

module.exports = function(config) {
    config.set({
      frameworks: ['mocha', 'chai'],
      files: ['test/**/*.js'],
      preprocessors: {
        // add webpack as preprocessor
        'test/**/*.js': ['webpack']
      },
      webpack: {
        // karma watches the test entry points
        // (you don't need to specify the entry option)
        // webpack watches dependencies
        // webpack configuration
      },
  
      webpackMiddleware: {
        // webpack-dev-middleware configuration
        stats: 'errors-only',
      },
      reporters: ['spec'],
      
      port: 9876,  // karma web server port
      colors: true,
      logLevel: config.LOG_INFO,
      browsers: ['ChromeHeadless'],
      autoWatch: false,
      // singleRun: false, // Karma captures browsers, runs the tests and exits
      concurrency: Infinity
    })
  }