Padwasabimasala

In order to better understand testing in Node I decided to work out the Bowling Game kata from scratch. The kata is an exercize to pratice the disciplines of good TDD. But is also a good starting point for learning a new environment.

The first step was to figure out how testing was done in NodeJS. After googling around I found a good starting point by Matthew Palmer. This example uses Mocha and Expect.js.

The next step was to figure out how to get a project initialized with Node. More searching revelaed that I could just use

  node init <my project>

but I wouldn't do it that way again. All I got was some annoying prompts that generated a package.json. Next time I would just generate this file by hand.

After doing some more reading about how mocha works, and with some experience using Chai the previous day, I decided to use Chai instead of Expect.js.

My final package.json looks like this.

{
  "name": "bowling-game-js",
  "version": "0.0.0",
  "description": "Bowling Game Kata in JS with Node",
  "main": "index.js",
  "scripts": {
    "test": "mocha test"
  },
  "author": "Matthew Thorley",
  "license": "BSD"
  ,"devDependencies": {
    "mocha": "*",
    "chai": "*"
  }

}

Note that in addition to adding the devDependencies for Mocha, and Chai, I also added the test command "mocha test" to scripts:test.

With that in place I could write my first test. I read some of the Mocha best practices and looked at a few example projects to see how things should be setup. Then I created a test directory, and my first test, test/bowlinggame.js. In other testing frameworks I've used in tht past test files usually were named testsomething or something_test. But the common practice in this ecosystem seems favor omitting the word 'test' from filenames.

  mkdir test
  vim test/bowling_game.js

Here's my first test.

var chai = require('chai')
chai.should()

var BowlingGame = require ('../bowling_game').BowlingGame

describe('new BowlingGame()', function() {
  it('should create a new BolwingGame', function() {
    game = new BowlingGame
    game.should.be.a('Object')
  })
})

This test fails because there is no bowlinggame file or BowlingGame object. Getting it to pass is easy to do. Just add a bowlinggame.js file to the root of the project and export a BowlingGame object in it.

  vim bowling_game.js

Content of bowling_game.js

exports.BowlingGame = function() {
}

When I run 'mocha tests' the tests pass.

Happy Hacking, MT