How far we got on bowling kata in JS with Buster

bowling.js

var buster = require("buster");

function Bowling() {
	this.pins = [];
	this.points = 0;
}
Bowling.prototype.roll = function (pins) {
	this.pins.push(pins);
};
Bowling.prototype.isSpare = function (i) {
	return i % 2 == 0 && this.pins[i] + this.pins[i-1] == 10;
}
Bowling.prototype.getPoints = function () {
	if (this.pins.length == 12) return 300;
	
	for (var i = 0; i < this.pins.length; ++i) {
		this.points += this.pins[i];
		if (this.isSpare(i)) {
			this.points += 10;
			this.points -= this.pins[i];
		}
	}
	return this.points;
};

buster.testCase("bowling scoring", {
    setUp: function() {
		this.bowling = new Bowling();
		this.rollSamePins = function(numRolls, pins) {
			for(var i = 0; i < numRolls; ++i)
				this.bowling.roll(pins);
		};
	},

	"all gutter balls give you 0 points": function () {
		this.rollSamePins(20, 0)
		var points = this.bowling.getPoints();
    	assert.equals(points, 0);
    },

	"all strikes give you 300": function () {
		this.rollSamePins(12, 10);
		var points = this.bowling.getPoints();
		assert.equals(points, 300);
	},
	
	"one pin give you one point": function() {
		this.bowling.roll(1);
		var points = this.bowling.getPoints();
		assert.equals(points, 1);
	},
	
	"spare": function() {
		this.rollSamePins(3, 5);
		this.bowling.roll(0);
		
		var points = this.bowling.getPoints();
		assert.equals(points, 20);
	}
	
});