FizzBuzz Ruby TDD

fizzbuzz.rb

#!/usr/local/bin/ruby -w

require 'test/unit'

class FizzBuzz
  def self.fizzbuzz(number)
    result = ""
    result << "Fizz" if is_divisible_by_three?(number)
    result << "Buzz" if is_divisible_by_five?(number)
    return result if result != ""
    number
  end
  
  def self.is_divisible_by_three?(number)
    is_divisible_by?(number, 3)
  end
  
  def self.is_divisible_by_five?(number)
    is_divisible_by?(number, 5)
  end
  
  def self.is_divisible_by?(number, divisor)
    number % divisor == 0
  end
end

class TestFizzBuzz < Test::Unit::TestCase
  def test_divisible_by_three
    # Should return true when multiples of 3 are informed
    assert_equal(true, FizzBuzz.is_divisible_by_three?(3), "Should return true")
    assert_equal(true, FizzBuzz.is_divisible_by_three?(6), "Should return true")
    assert_equal(false, FizzBuzz.is_divisible_by_three?(5), "Should return false")
  end
  
  def test_divisible_by_five
    # Should return true when multiples of 5 are informed
    assert_equal(true, FizzBuzz.is_divisible_by_five?(5), "Should return true")
    assert_equal(true, FizzBuzz.is_divisible_by_five?(10), "Should return true")
    assert_equal(false, FizzBuzz.is_divisible_by_five?(3), "Should return false")
  end
  
  def test_fizzbuzz_number
    # Should return only the number
    assert_equal(1, FizzBuzz.fizzbuzz(1))
    assert_equal(2, FizzBuzz.fizzbuzz(2))
  end
  
  def test_fizz
    # Should return "Fizz" for multiples of 3
    assert_equal("Fizz", FizzBuzz.fizzbuzz(3))
    assert_equal("Fizz", FizzBuzz.fizzbuzz(6))
  end
  
  def test_buzz
    # Should return "Buzz" for multiples of 5
    assert_equal("Buzz", FizzBuzz.fizzbuzz(5))
    assert_equal("Buzz", FizzBuzz.fizzbuzz(10))
  end
  
  def test_fizzbuzz
    # Should return "FizzBuzz" for multiples of 15
    assert_equal("FizzBuzz", FizzBuzz.fizzbuzz(15))
    assert_equal("FizzBuzz", FizzBuzz.fizzbuzz(30))
  end
end

1..101.times do |number|
  puts FizzBuzz.fizzbuzz(number)
end