Testing react and redux with karma and mocha

I've started working with React and Redux and I'd like to write tests for it using Karma with Mocha and PhantomJS2. I'm using the sources here as base: http://ift.tt/1TNQfBi . I basically want to run the tests there in Karma using Phantom instead of using node and the "npm test".

I've set up and installed the required packages for karma:

package.json

"scripts": {
    "test:karma": "karma start",
},
"karma": "^0.13.21",
"karma-babel-preprocessor": "^6.0.1",
"karma-mocha": "^0.2.2",
"karma-phantomjs2-launcher": "^0.5.0",
"phantomjs2": "^2.2.0",

And I've tried to figure out how to build my karma.config.js but I don't seem to get my tests to run and this is where I need the help.

karma.config.js

module.exports = function(config) {
    process.env.PHANTOMJS_BIN = './node_modules/phantomjs2/lib/phantom/bin';
    config.set({
        basePath: './',
        frameworks: ['mocha'],
        plugins: [ 'karma-mocha',  'karma-phantomjs2-launcher', 'karma-babel-preprocessor' ],
        files: [
            "components/Counter.js",
            "test/components/Counter.spec.js"
        ],
        preprocessors: {
            "components/Counter.js": ["babel"],
            "test/components/Counter.spec.js": ["babel"]
        },
        babelPreprocessor: {
            options: {
                "presets": ["es2015", "react"],
            }
        },
        reporters: ['progress'],
        browsers: ['PhantomJS2'],
        port: 9099,
        runnerPort: 9100,
        urlRoot: '/',
        colors: true,
        logLevel: config.LOG_INFO,
        autoWatch: false,
        singleRun: false,
        concurrency: Infinity
    })
}