a_test.md

Credit Card Validator!

now with automated tests

Austin Wood

---

To Run

1. run ruby credit_check_test.rb

To Debug via Pry

1. Make sure you have installed Pry (gem install pry)
2. Insert binding.pry on the line you want to break on in credit_check.rb
3. Uncomment bottom two lines of credit_check.rb to create test card number
4. run ruby credit_check.rb and pry should pause where you put the break marker

credit_check.rb

require 'pry'

class CreditCheck
  attr_accessor :card_number

  def validate(card_number)
    if card_number == ''
      false
    else
      card_arr = card_number.each_char.map.with_index do |n,i|
        num = n.to_i
        if card_number.length % 2 == 0
          i % 2 == 0 ? num *= 2 : num
        else # i.e. American Express
          i % 2 == 1 ? num *= 2 : num
        end
      end.map { |n| n >= 10 ? (n % 10) + 1 : n }.reduce :+

      if card_arr % 10 == 0
        # puts "The number is valid!"
        card_number = true
      else
        # puts "The number is invalid!"
        card_number = false
      end
    end
  end
end

# Debugging purposes
# tester = CreditCheck.new
# tester.validate('6011797668867828') # should return true

credit_check_test.rb

require 'minitest/autorun'
require 'minitest/pride'
require './credit_check'

class CreditCheckTest < MiniTest::Test
  def test_empty_string_is_invalid
    checker = CreditCheck.new
    result = checker.validate('')
    assert_equal false, result
  end

  def test_single_zero_char_is_valid
    checker = CreditCheck.new
    result = checker.validate('0')
    assert_equal true, result
  end

  def test_single_nonzero_char_is_invalid
    checker = CreditCheck.new
    result = checker.validate('1')
    assert_equal false, result
  end

  def test_small_strings
    checker = CreditCheck.new
    result = checker.validate('42')
    assert_equal true, result
    result = checker.validate('50')
    assert_equal false, result
  end

  def test_medium_strings
    checker = CreditCheck.new
    result = checker.validate('42424242')
    assert_equal true, result
    result = checker.validate('50505050')
    assert_equal false, result
  end

  def test_actual_card_numbers
    checker = CreditCheck.new
    result = checker.validate('5541808923795240')
    assert_equal true, result
    result = checker.validate('4024007136512380')
    assert_equal true, result
    result = checker.validate('5541801923795240')
    assert_equal false, result
    result = checker.validate('4024007106512380')
    assert_equal false, result
  end

  def test_american_express
    checker = CreditCheck.new
    result = checker.validate('342804633855673')
    assert_equal true, result
    result = checker.validate('342801633855673')
    assert_equal false, result
  end
end