Kata

.rspec

--color

string_calculator.rb

class StringCalculator
  def initialize(numbers)
    @numbers = numbers
    check_validity!
  end

  def add
    integers.reduce(0, :+)
  end

  def delimeter
    if match = numbers.match(%r(//(.*)\n))
      match[1]
    else
      /\n|,/
    end
  end

  private
  attr_reader :numbers
  def check_validity!
    delimeters = numbers.scan(delimeter)
    raise if delimeters.count > integers.count
    negatives = integers.select { |num| num < 0 }
    raise(ArgumentError, "negatives not allowed: #{negatives.join(", ")}") if negatives.any?
  end

  def all_numbers
    numbers.split(delimeter).map(&:to_i)
  end

  def integers
    all_numbers.reject(&:zero?).reject {|num| num > 1000 }
  end
end

string_calculator_spec.rb

require 'rspec'
require_relative 'string_calculator'

describe StringCalculator do
  let(:calculator) { StringCalculator }
  it 'returns 0 when input is an empty string' do 
    expect(calculator.new("").add).to eq(0)
  end

  it 'returns the number passed in for a single number' do
    expect(calculator.new('1').add).to eq(1)
  end

  it 'returns sum of two comma-separated numbers' do
    expect(calculator.new('1,2').add).to eq(3)
  end

  it 'returns the sum of any number of numbers' do
    expect(calculator.new('1,5,6,7').add).to eq(19)
  end

  it 'returns the sum of numbers separated by new lines or commas' do
    expect(calculator.new("1\n2,3").add).to eq(6)
  end

  it 'does not allow two adjacent delimeters' do
    expect { calculator.add("1,\n") }.to raise_error
  end

  it 'works for multi-digit numbers' do
    expect(calculator.new('13,14,15').add).to eq(42)
  end

  describe 'delimeter definition' do
    it 'is defined by //<delimeter>\n' do
      expect(calculator.new("//&\n1&2&3").delimeter).to eq('&')
    end

    it 'uses its new delimeter for calculating sums' do
      expect(calculator.new("//&\n1&2&3").add).to eq(6)
    end

    it 'raises an exception when two or more delimeters are adjacent' do
      expect { calculator.new("//&\n1&2&&&3").add }.to raise_error
    end

    it 'accepts delimeters of any length' do
      expect(calculator.new("//*^\n1*^2*^3").add).to eq(6)
    end

    it 'allows multiple delimeters' do
      expect(calculator.new("//[@][%]\n1@2%3").add).to eq(6)
    end

  end

  describe 'negative numbers' do
    it 'raises an exception' do
      expect { calculator.new("1,-5").add }.to raise_error
    end

    it 'returns the number that raised the exception' do
      expect { calculator.new("1,-5").add }.to raise_error(ArgumentError, "negatives not allowed: -5")
    end

    it 'returns all negative numbers that were included' do
      expect { calculator.new("-1,-5").add }.to raise_error(ArgumentError, "negatives not allowed: -1, -5")
    end
  end

  it 'ignores numbers larger than 1000' do
    expect(calculator.new("2,1005").add).to eq(2)
  end
end