roman_numbers_kata_spec.rb

class NumberConverter

  def to_roman(number)
    numbers = {
        1000 => {roman: 'M', prev: 100},
        500 => {roman: 'D', prev: 100},
        100 => {roman: 'C', prev: 10},
        50 => {roman: 'L', prev: 10},
        10 => {roman: 'X', prev: 1},
        5 => {roman: 'V', prev: 1},
        1 => {roman: 'I', prev: 0},
    }
    numbers.each do |normal, n|
      return n[:roman] if number == normal
      return n[:roman] + to_roman(number - normal) if number > normal
      return numbers[n[:prev]][:roman] + to_roman(number + n[:prev]) if number.between?(normal - n[:prev] , normal - 1)
    end
  end
end

describe NumberConverter do
  before do
    @converter = NumberConverter.new
  end
  {
      1 => 'I',
      2 => 'II',
      3 => 'III',
      4 => 'IV',
      5 => 'V',
      6 => 'VI',
      7 => 'VII',
      8 => 'VIII',
      9 => 'IX',
      10 => 'X',
      11 => 'XI',
      12 => 'XII',
      19 => 'XIX',
      20 => 'XX',
      30 => 'XXX',
      40 => 'XL',
      45 => 'XLV',
      46 => 'XLVI',
      49 => 'XLIX',
      50 => 'L',
      51 => 'LI',
      94 => 'XCIV',
      99 => 'XCIX',
      100 => 'C',
      101 => 'CI',
      146 => 'CXLVI',
      149 => 'CXLIX',
      249 => 'CCXLIX',
      500 => 'D',
      480 => 'CDLXXX',
      494 => 'CDXCIV',
      495 => 'CDXCV',
      499 => 'CDXCIX',
      999 => 'CMXCIX',
      1000 => 'M',
      2751 => 'MMDCCLI',
      5999 => 'MMMMMCMXCIX'
  }.each do |normal_number, roman_number|
    it "арабская #{normal_number} = римская #{roman_number}" do
      expect(@converter.to_roman normal_number).to eql roman_number
    end
  end
end