BoulderRBTesting

fizz_buzz.rb

class FizzBuzz
  def print(range)
    raise ArgumentError unless range.is_a? Range
    raise ArgumentError unless range.min > 0

    range.map do |num|
      if num % 3 == 0
        'Fizz'
      elsif num % 5 == 0
        'Buzz'
      elsif num % 15 == 0
        'FizzBuzz'
      else
        num.to_s
      end
    end
  end
end

spec.rb

require_relative 'fizz_buzz'
require 'minitest/autorun'

describe 'FizzBuzz' do
  before do
    @fizzbuzz = FizzBuzz.new
    @range = 1..20
  end

  # Output expected:
  # [1, 2, "Fizz", 4, "Buzz", 6, 7, 8, "Fizz", "Buzz", 11, "Fizz", 13, 14, "FizzBuzz", ...]

  describe '.print' do
    it 'should return an array' do
      @fizzbuzz.print(@range).must_be_instance_of Array
    end

    it "should print 'Fizz' for multiples of 3" do
      @fizzbuzz.print(@range)[2].must_equal 'Fizz'
    end

    it "should print 'Buzz' for multiples of 5" do
      @fizzbuzz.print(@range)[4].must_equal 'Buzz'
    end

    it "should print 'FizzBuzz' for multiples of 15" do
      @fizzbuzz.print(@range)[14].must_equal 'FizzBuzz'
    end

    it 'should print the given number if not a multiple of 3, 5, or 15' do
      @fizzbuzz.print(@range)[14].must_equal '14'
    end

    it 'should throw an argument error if an argument is not given' do
      proc { @fizzbuzz.print }.must_raise ArgumentError
    end

    it "should raise an argument error if the argument isn't a range" do
      proc { @fizzbuzz.print(4) }.must_raise ArgumentError
    end

    it 'should throw an argument error if a zero is in the range' do
      proc { @fizzbuzz.print(0..10) }.must_raise ArgumentError
    end

    it 'should throw an argument error if a negative number is in the range' do
      proc { @fizzbuzz.print(-1..5) }.must_raise ArgumentError
    end
  end
end

This is a simple FizzBuzz implementation written to demonstrate MiniTest in Ruby. Presented March 2015 to the Beginners' Track at the Boulder Ruby meetup.

The requirements are:

• Should take a range of positive integers
• Should print 'Fizz' for multiples of 3
• Should print 'Buzz' for multiples of 5
• Should print 'FizzBuzz' for multiples of 15
• Should not affect other numbers
• Should return an array of the results