Fizzbuzz

commentary.md

Fizzbuzz

There are many ways to do this kata, including defining a refinement on the integer class as I did here. There are also many ways to print the fizzbuzz data including converting an integer to its representative in fizzbuzz or creating an array of numbers up to that integer with their fizzbuzz contents.

Printing to STDOUT

To print each element of an array to STDOUT it can be as simple as requiring a puts in front of the array. Or if the program is intended to be a ruby script, calling #each and printing each element of that array. I do not think that creating an array that prints each line should be part of this refinement, but instead could be a refinement on the array class, or a special class by itself with a method like:

def print_each(array)
  array.each do |element|
    p element
  end
end

To create an executable script so that this: ruby fizz_buzz.rb 3 prints:

1
2
fizz

Please see the file print_fizzbuzz, because we have tested the refinement, we can be sure that the correct numbers are printed to STDOUT

fizzbuzz.rb

module Fizzbuzz
  refine Integer do
    def to_fizzbuzz
      case
      when self.fizzbuzz? then 'fizzbuzz'
      when self.buzz? then 'buzz'
      when self.fizz? then 'fizz'
      else self
      end
    end

    def fizzbuzz_array
      return [] if self < 1
      # unfortunately symbol_to_proc does not work yet for refinements
      # i.e. (1..self).map(&:to_fizzbuzz)
      (1..self).map{ |int| int.to_fizzbuzz }
    end

    def fizzbuzz?
      self % 15 == 0
    end

    def buzz?
      self % 5 == 0
    end

    def fizz?
      self % 3 == 0
    end
  end
end

fizzbuzz_spec.rb

# this spec requires RSpec installed

require_relative 'fizzbuzz'

describe 'Fizzbuzz' do
  using Fizzbuzz

  context '#to_fizzbuzz' do
    specify { expect(1.to_fizzbuzz).to eq 1 }
    specify { expect(2.to_fizzbuzz).to eq 2 }
    specify { expect(3.to_fizzbuzz).to eq 'fizz' }
    specify { expect(5.to_fizzbuzz).to eq 'buzz' }
    specify { expect(6.to_fizzbuzz).to eq 'fizz' }
    specify { expect(7.to_fizzbuzz).to eq 7 }
    specify { expect(15.to_fizzbuzz).to eq 'fizzbuzz' }
  end

  context '#to_fizzbuzz array' do
    specify { expect(-1.fizzbuzz_array).to eq [] }
    specify { expect(0.fizzbuzz_array).to eq [] }
    specify { expect(1.fizzbuzz_array).to eq [1] }
    specify { expect(2.fizzbuzz_array).to eq [1, 2] }
    specify { expect(3.fizzbuzz_array).to eq [1, 2, 'fizz'] }
    specify { expect(5.fizzbuzz_array).to eq [1, 2, 'fizz', 4, 'buzz'] }
  end
end

print_fizzbuzz.rb

require_relative 'fizzbuzz'
using Fizzbuzz

# ARGV is an array of string arguments passed in after ``ruby <filename>``
# As such #first and #to_i are necessary to convert it to an integer/fixnum
# to use the refinement defined in fizzbuzz.rb.
# with this, you can print to STDOUT with 
# ruby print_fizzbuzz.rb 15
puts ARGV.first.to_i.fizzbuzz_array