Ruby Unique methods

readme.md

Demo code

This is a quick demo for a student on how to solve a problem in ruby, creating their own built-in version of a ruby method.

unique.rb

require 'test/unit'

def unique_array_unique(arr)
  arr.uniq # Should be self explanatory, all arrays have a uniq method for removing duplicate values
end

def unique_array_self(arr)
  new_arr = [] # start by creating a new array
  arr.each do |a| # loop through the existing array
    unless new_arr.include?(a) # unless will only run if the statement returns false
      new_arr.push(a) # If the item does not exist in the new array, add it.  Otherwise, do nothing (No-op)
    end
  end
  new_arr # return the new array at the end
end


class ArrayTest < Test::Unit::TestCase
  # Must use the test_ method name to indicate that you want this to be a test
  def test_unique_array_unique_will_remove_duplicate_items
    arr_one = %w(bat balls gloves drinks balls) # Alternative syntax for ['bat', 'balls', 'gloves']
    arr_two = unique_array_unique(arr_one) # Use the built-in unique method.
    # The first position is the expected outcome, which will be no duplicate balls entry.
    # The second position is the actual outcome.  The third is the error message if it fails.
    assert_equal(%w(bat balls gloves drinks).sort, arr_two.sort, 'Array does not match!')
    p arr_one, arr_two
  end

  def test_unique_array_self_will_remove_duplicate_items
    arr_one = %w(bat balls gloves drinks balls)
    # Exactly the same as above, but uses the method that we created.
    arr_two = unique_array_self(arr_one)
    assert_equal(%w(bat balls gloves drinks).sort, arr_two.sort, 'Array does not match!')
    p arr_one, arr_two
  end

end