Coin change kata

coinchange.spec.coffee

_ = require 'underscore'

changeForDenomination = (denomination, amount) ->
  to = Math.floor(amount / denomination)
  if to > 0 then [1..to].map () -> denomination else []

makeChange = (amount, denominations = [25, 10, 5 , 1]) ->
  denomination = _.first denominations
  if denomination
    changeForDenomination(denomination, amount)
      .concat(makeChange amount % denomination, _.rest denominations)
  else
    []
  

describe 'makeChange()', ->

  it 'returns [1] for 1', ->
    expect(makeChange 1).toEqual [1]

  it 'returns [1, 1] for 2', ->
    expect(makeChange 2).toEqual [1, 1]

  it 'returns [5] for 5', ->
    expect(makeChange 5).toEqual [5]

  it 'returns [5, 1] for 6', ->
    expect(makeChange 6).toEqual [5, 1]

  it 'returns [10] for 10', ->
    expect(makeChange 10).toEqual [10]
  
  it 'returns [10, 5, 1] for 16', ->
    expect(makeChange 16).toEqual [10, 5, 1]

  it 'returns [10, 5, 1, 1] for 17', ->
    expect(makeChange 17).toEqual [10, 5, 1, 1]

  it 'returns [25] for 25', ->
    expect(makeChange 25).toEqual [25]

  it 'returns [25, 25, 10, 5, 1, 1] for 67', ->
    expect(makeChange 67).toEqual [25, 25, 10, 5, 1, 1]