karma.conf.js

module.exports = (config) => {
  config.set({
    // base path that will be used to resolve all patterns (eg. files, exclude)
    basePath: '',

    // frameworks to use
    // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
    frameworks: ['jasmine'],

    // list of files / patterns to load in the browser
    files: [
      'src/**/*.js',
      'test/**/*.spec.js',
    ],

    // list of files to exclude
    exclude: [],

    // preprocess matching files before serving them to the browser
    // available preprocessors:
    // https://npmjs.org/browse/keyword/karma-preprocessor
    preprocessors: {
      '**/src/**/*.js': ['coverage', 'babel'],
      'test/**/*.spec.js': ['babel'],
    },

    // test results reporter to use
    // possible values: 'dots', 'progress'
    // available reporters: https://npmjs.org/browse/keyword/karma-reporter
    reporters: ['mocha'],

    // web server port
    port: 9876,

    // enable / disable colors in the output (reporters and logs)
    colors: true,

    // level of logging
    // possible values: config.LOG_DISABLE || config.LOG_ERROR ||
    // config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
    logLevel: config.LOG_INFO,

    // enable / disable watching file and executing tests whenever any file
    // changes
    autoWatch: true,

    // start these browsers
    // available browser launchers:
    // https://npmjs.org/browse/keyword/karma-launcher
    browsers: ['PhantomJS'],

    // Continuous Integration mode
    // if true, Karma captures browsers, runs the tests and exits
    singleRun: false,

    // Concurrency level
    // how many browser should be started simultaneous
    concurrency: Infinity,
    // concurrency: 1,

    babelPreprocessor: {
      filename(file) {
        return file.originalPath.replace(/\.js$/, '.es5.js');
      },
      sourceFileName(file) {
        return file.originalPath;
      },
    },

    coverageReporter: {
      type: 'html',
      // type: 'text-summary',
      dir: 'coverage/',
    },
  });
};