Example karma conf

gistfile1.js

grunt.initConfig({
    karma: {
        unitTests: {
            singleRun: true,
            browsers: ['PhantomJS'],
            frameworks: ['mocha', 'sinon', 'expect'],
            options: {
                files: [
                    'path/to/codemirror',
                    'path/to/your/source/code',
                    'path/to/your/tests'
                ],
                reporters: ['mocha']
            }
        }
    }
});