roman_numerals

roman_numerals

def roman_numerals(number)
  if number < 0 || number > 3000
    raise TypeError.new 'Must be any number from 0 to 3000'
  end 
   
  ones = {0 => '', 1 => 'I', 2 => 'II', 3 => 'III', 4 => 'IV', 5 => 'V', 6 => 'VI', 7 => 'VII', 8 => 'VIII', 9 => 'IX'}
  tens = {0 => '', 1 => 'X', 2 => 'XX', 3 => 'XXX', 4 => 'XL', 5 => 'L', 6 => 'LX', 7 => 'LXX', 8 => 'LXXX', 9 => 'XC'}
  hundreds = {0 => '', 1 => 'C', 2 => 'CC', 3 => 'CCC', 4 => 'CD', 5 => 'D', 6 => 'DC', 7 => 'DCC', 8 => 'DCCC', 9 => 'CM'}
  thousands = {0 => '', 1 => 'M', 2=> 'MM', 3 => 'MMM'}

  ones_numeral = ones[number % 10]
  tens_numeral = tens[(number % 100) / 10]
  hundreds_numeral = hundreds[(number % 1000) / 100]
  thousands_numeral = thousands[(number % 10000) / 1000]

  thousands_numeral + hundreds_numeral + tens_numeral + ones_numeral
end  

roman_numerals_spec

require 'rspec'
require 'roman_numerals'

describe 'roman_numerals' do
  it 'raises an exception for an integer less than 0 or greater than 3000' do
    expect {roman_numerals(-3)}.to raise_exception
    expect {roman_numerals(3001)}.to raise_exception
    expect {roman_numerals(1.5)}.to raise_exception 
  end

  it 'raises an exception for a non-number input' do
    expect {roman_numerals("foo")}.to raise_exception
    expect {roman_numerals(false)}.to raise_exception
    expect {roman_numerals([1, 2, 3])}.to raise_exception   
  end

  it 'translates single digits into roman numerals' do
    roman_numerals(1).should eq "I"
    roman_numerals(2).should eq "II"
    roman_numerals(3).should eq "III"
    roman_numerals(4).should eq "IV"
    roman_numerals(5).should eq "V"
    roman_numerals(6).should eq "VI"
    roman_numerals(7).should eq "VII"
    roman_numerals(8).should eq "VIII"
    roman_numerals(9).should eq "IX"
  end

  it 'translates double digits into roman numerals' do
    roman_numerals(10).should eq "X"
    roman_numerals(20).should eq "XX"
    roman_numerals(30).should eq "XXX"
    roman_numerals(40).should eq "XL"
    roman_numerals(50).should eq "L"
    roman_numerals(60).should eq "LX"
    roman_numerals(70).should eq "LXX"
    roman_numerals(80).should eq "LXXX"
    roman_numerals(90).should eq "XC"  
  end

  it 'translates three-digit numbers digits into roman numerals' do
    roman_numerals(100).should eq "C"
    roman_numerals(200).should eq "CC"
    roman_numerals(300).should eq "CCC"
    roman_numerals(400).should eq "CD"
    roman_numerals(500).should eq "D"
    roman_numerals(600).should eq "DC"
    roman_numerals(700).should eq "DCC"
    roman_numerals(800).should eq "DCCC"
    roman_numerals(900).should eq "CM"  
  end

  it 'translates numbers above 999 into roman numerals' do
    roman_numerals(1000).should eq "M"
    roman_numerals(2000).should eq "MM"
    roman_numerals(3000).should eq "MMM"
  end

  it 'translates any number from 0 to 3000' do
    roman_numerals(0).should eq ""
    roman_numerals(2222).should eq "MMCCXXII"
    roman_numerals(345).should eq "CCCXLV"
    roman_numerals(2006).should eq "MMVI"
    roman_numerals(634).should eq "DCXXXIV"
  end
end