String Comparing Exercise

string-comparison.rb

#!/usr/bin/env ruby
require 'minitest'
require 'minitest/spec'
require 'minitest/autorun'
require 'pry-byebug'

# Hi! We have a challenge for you to complete.
#
# We've defined the differences between two strings to be the number of
# characters that don't match. For example, "bob" and "rob" are mostly the same
# except for their first letter, so their differences count would be 1.
#
# Please fill in the `differences` method below such that it passes all the
# tests. You can run this file with ruby and it should let you know if it
# passes or fails. (`ruby string_comparison.rb` in your terminal)
#
# Once you've completed this challenge, send the file back to us (email or
# however we've sent it to you is fine) and we'll take a look.
#
# Thanks and good luck!
# -Josh Szmajda

# original stand alone method used for tests.
def differences(s1, s2)
  StringCombo.new(s1, s2).differences
end

# Object to hold both strings and manipulate params as attributes
class StringCombo
  attr_reader :s1, :s2

  def initialize(s1, s2)
    @s1 = s1
    @s2 = s2
  end

  def differences
    difference_counter
  end

  private

  def smallest_length
    @s1.length <= @s2.length ? @s1.length : @s2.length
  end

  def difference_counter
    count = 0
    @s1.downcased_array.first(smallest_length).each_with_index do |char, i|
      count += 1 if char != @s2.downcased_array[i]
    end
    count
  end
end

# Reopen String class
class String
  def downcased_array
    downcase.split('')
  end
end

# Tests
describe 'String Comparison' do
  it 'returns 0 when the strings are empty' do
    differences('', '').must_equal(0)
  end

  it 'returns 0 when the strings are identical' do
    differences('Robert', 'Robert').must_equal(0)
  end

  it 'returns 3 for this small test' do
    differences('Bob', 'Sam').must_equal(3)
  end

  it 'is 2 for this longer sample' do
    differences('Jessica Q. Smith', 'Jessica R. Smyth').must_equal(2)
  end

  it 'is 1 in this case' do
    differences('Samantha', 'Semantha').must_equal(1)
  end

  it 'ignores case matching' do
    differences('Yasha Emirhan', 'Yesha EmIrhan').must_equal(1)
  end

  it 'ignores the extra length on the second string' do
    differences('Fahri Jordan', 'Damian Tomoson').must_equal(11)
  end

  it 'ignores the extra length of the first string' do
    differences('Randell Vilhelmas', 'Henri Nadav').must_equal(10)
  end
end

This file started out with an empty differences method and all the tests in their current state.

I basically got the tests passing without messing with them.