テストランナーkarmaをとりあえず使ってみる方法 ref: http://qiita.com/taizo/items/04c80dcd2841cb1119a8

app.js

var Foo = function() {
};
Foo.prototype.sum = function(x, y) {
  return x + y;
};
Foo.prototype.div = function(x, y) {
  return x / y;
};

app_test.js

describe('Foo', function() {
  it("2 plus 3 is 5", function() {
    var foo = new Foo();
    expect(foo.sum(2,3)).toBe(5);
  });
  it("10 divided 5 is 2", function() {
    var foo = new Foo();
    expect(foo.div(10,5)).toBe(2);
  });
});

file0.js

$ npm install -g karma

file1.txt

$ karma init
Which testing framework do you want to use ?
Press tab to list possible options. Enter to move to the next question.
> jasmine # 選択肢がある場合は、タブで切り替えが出来る

file5.txt

$ karma start

karma.conf.js

module.exports = function(config) {
  config.set({
    basePath: '',
    frameworks: ['jasmine'],
    files: [
      'app.js',
      'app_test.js'
    ],
    reporters: ['progress'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['Chrome'],
    singleRun: true
  });
};