birthday_calculation_test.rb

require 'test/unit'
require 'date'

class BirthdayCalculationTest < Test::Unit::TestCase

  def test_calculation
    bday  = Birthday.new(1981, 12, 4)
    today = Date.new(2008, 11, 4)
    assert_equal 30, bday.days_from(today)
  end
  
  def test_lower_month_number
    bday  = Birthday.new(1981, 1,  4)
    today = Date.new(2008, 11, 4)
    assert_equal 61, bday.days_from(today)
  end
  
  def test_leap_year
    bday  = Birthday.new(1981, 3, 4)
    today = Date.new(2008, 2, 4)
    assert_equal 29, bday.days_from(today)
    today = Date.new(2009, 2, 4)
    assert_equal 28, bday.days_from(today)
  end

end

class Birthday < Date
  def days_from(from_day)
    # return number of days (without taking birthday year in consideration)
  end
end