mocha + karma coverage

karma.conf

var baseConfig = require('./karma.conf.js');

module.exports = function (config) {
    // Load base config
    baseConfig(config);

    // Override base config
    config.set({
        
        ...
        
        coverageReporter: {
            type:   'lcov',
            dir:    'reports',
            subdir: 'coverage'
        }
    });
};