Karma, PhantomJS and Mocha Setup

karma.config.js

const path = require("path");

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

        client: {
            mocha: {
                reporter: "html",
                ui: "bdd"
            }
        },
        coverageReporter: {
            type: "html",
            dir: "cache/coverage/"
        },
        // frameworks to use
        // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
        frameworks: ["mocha", "chai"],

        // list of files / patterns to load in the browser
        files: ["tests/root.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: {
            "tests/root.js": ["webpack", "sourcemap"]
        },

        webpack: {
            devtool: "inline-source-map",
            module: {
                loaders: [
                    {
                        test: /\.js$/,
                        loader: "babel-loader",
                        exclude: path.resolve(__dirname, "node_modules"),
                        query: {
                            presets: ["es2015"]
                        }
                    }
                ]
            }
        },
        // test results reporter to use
        // possible values: 'dots', 'progress'
        // available reporters: https://npmjs.org/browse/keyword/karma-reporter
        reporters: ["progress", "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
    });
};