String Calculator.rb

# http://osherove.com/tdd-kata-1/

class StringCalculator
  def add(string)
    # Default delimiters to split string
    delims = %w(, \n)

    # If string begins with "//[delimiter]\n" include delimiter to array of delimiters
    if string.match(/^\/\/.+/)
      match, string = string.split('\n', 2)
      delims.concat(match.to_s[3..-2].split(']['))
    end

    # Gets accepted numbers from string
    numbers = string.split(Regexp.union(delims)).map(&:to_i).reject { |n| n > 1000 }

    # Gets any negative numbers
    negatives = numbers.select { |n| n < 0 }

    # Raises an ArgumentError if negative numbers are found
    raise ArgumentError.new "negatives not allowed: #{negatives.join(', ')}" unless negatives.none?

    # Returns sum of numbers
    numbers.inject(0) { |sum, num| sum += num }
  end
end

# class Test
#   attr_reader :pass_count, :fail_count

#   def initialize(calc)
#     @pass_count = @fail_count = 0
#     @calc = calc
#   end

#   def this(desc, method, string, expected)
#     puts "Test: #{desc}"

#     begin
#       actual = @calc.send(method, string)
#     rescue ArgumentError => e
#       actual = e.message
#     end

#     if actual == expected
#       puts "\tPassed!\n\n"
#       @pass_count += 1
#     else
#       puts "\tFailed! Expected #{actual} to equal #{expected}\n\n"
#       @fail_count += 1
#     end
#   end
# end

# test = Test.new(StringCalculator.new)

# test.this("expect empty string to equal 0", 'add', '', 0)
# test.this("expect '1' to equal 1", 'add', '1', 1)
# test.this("expect '1,2' to equal 3", 'add', '1,2', 3)
# test.this("expect '1,2,3' to equal 6", 'add', '1,2,3', 6)

# rand_array = (1..rand(10) + 1).map { |n| n * rand(10) }
# test.this("expect an unknown amount of numbers to pass", 'add', rand_array.join(','), rand_array.inject(&:+))

# test.this("expect '1\\n2,3' to equal 6", 'add', '1\n2,3', 6)
# test.this("expect '//[;]\\n1;2' to equal 3", 'add', '//[;]\n1;2', 3)
# test.this("expect negative numbers to throw an exception", 'add', '-1', 'negatives not allowed: -1')
# test.this("expect numbers bigger than 1000 to be ignored", 'add', '2,1001', 2)
# test.this("expect '//[***]\\n1***2***3' to equal 6", 'add', '//[***]\n1***2***3', 6)
# test.this("expect '//[*][%]\\n1*2%3' to equal 6", 'add', '//[*][%]\n1*2%3', 6)
# test.this("expect multiple delimiters with lengths longer than one character to pass", 'add', '//[@@@][*][^^]\n1@@@2*3^^4', 10)

# puts "#{test.pass_count} tests passed. #{test.fail_count} tests failed."

require 'minitest/autorun'

describe StringCalculator do

  let(:calc) { StringCalculator.new }

  describe "when given an empty string" do
    it "returns zero" do
      calc.add('').must_equal 0
      calc.add(' ').must_equal 0
      calc.add('  ').must_equal 0
    end
  end

  describe "when given a single number string" do
    it "returns the number" do
      calc.add('1').must_equal 1
      calc.add('2').must_equal 2
      calc.add('345').must_equal 345
    end
  end

  describe "when given a two number string" do
    it "returns the sum of the two numbers" do
      calc.add('1,2').must_equal 3
      calc.add('2,3').must_equal 5
      calc.add('45,67').must_equal 112
    end
  end

  describe "when given a three number string" do
    it "returns the sum of the three numbers" do
      calc.add('1,2,3').must_equal 6
      calc.add('4,5,6').must_equal 15
      calc.add('78,90,12').must_equal 180
    end
  end

  describe "when given an unknown amount of numbers string" do
    it "returns the sum of the numbers" do
      3.times do
        rand_array = 1.upto(rand(10) + 1).map { |n| n * rand(10) }
        calc.add(rand_array.join(',')).must_equal rand_array.inject(&:+)
      end
    end
  end

  describe "when given a string of with '\\n'" do
    it "returns the sum of the numbers delimited by '\\n' and ','" do
      calc.add('1\n2,3').must_equal 6
      calc.add('4\n5\n6').must_equal 15
      calc.add('7,8\n9').must_equal 24
    end
  end

  describe "when given a string that starts with '//[;]\\n'" do
    it "returns the sum of the numbers delimited by ';', '\\n' and ','" do
      calc.add('//[;]\n1;2').must_equal 3
      calc.add('//[;]\n3,4;5\n6').must_equal 18
      calc.add('//[;]\n7;8;9;0').must_equal 24
    end
  end

  describe "when given a string with negative numbers" do
    it "raises an ArgumentError error" do
      3.times do
        negatives = 1.upto(rand(10) + 1).map { |n| -(n * rand(10) + 1) }
        err = assert_raises(ArgumentError) { calc.add(negatives.join(',')) }
        err.message.must_equal "negatives not allowed: #{negatives.join(', ')}"
      end
    end
  end

  describe "when given a string with a number greater than 1000" do
    it "ignores numbers greater than 1000 and returns the sum" do
      calc.add('1,1001').must_equal 1
      calc.add('2,1000').must_equal 1002
      calc.add('1001,2002,3003').must_equal 0
    end
  end

  describe "when given a string with a multi character custom delimiter" do
    it "delimits the string with the multi character delimiter and returns the sum" do
      calc.add('//[***]\n1***2').must_equal 3
      calc.add('//[***]\n3,4***5').must_equal 12
      calc.add('//[abc]\n6abc7\n8abc9').must_equal 30
    end
  end

  describe "when given a string with multiple custom delimiters" do
    it "delimits the string with custom delimiters and returns the sum" do
      calc.add('//[*][%]\n1*2%3').must_equal 6
      calc.add('//[*][%]\n4*5*6%7%8').must_equal 30
      calc.add('//[!][@][#][$][%][^][&][*]\n1!2@3#4$5%6^7&8*9').must_equal 45
    end
  end

  describe "when given a string with multiple custom delimiters of multiple characters each" do
    it "delimits the string with custom delimiters and returns the sum" do
      calc.add('//[@@@][*][^^]\n1@@@2*3^^4').must_equal 10
      calc.add('//[!!!][;;][!@#]\n5!!!6;;7!@#8').must_equal 26
      calc.add('//[***][**][*]\n1***2**3*4').must_equal 10
    end
  end
end