Today's Kata 11-13-2015

mixin_module.rb

=begin
# Question 1. A mixin is a module whose methods you want to use in more than one class. One popular interview question is: How do you use module methods as class methods, and how to you use them as instance methods? In other words, given this module ...

module Mixin

  def method1
    'method1'
  end

end

# and class Charlie

class Charlie
end

# ... how do you mix module "Mixin" into class Charlie, such that I can call Charlie.method1? How do you mix module "Mixin" into Charlie, such that I can call method1 as Charlie.new.method1?
=end

Mixin = Module.new do
  def method1
    'method1'
  end
end

Charlie = Class.new do
  self.include Mixin
  self.extend Mixin
end

require 'minitest/autorun'
class MixinTest < Minitest::Test

  def test_class_method_extend_mixin
    assert_equal 'method1', Charlie.method1
  end

  def test_instance_method_include_mixin
    charlie = Charlie.new
    assert_equal 'method1', charlie.method1
  end
end

mixin_module_2.rb

=begin
# Question 2. Now suppose we change our Mixin to this:

module Mixin

  def self.method1
    'method1'
  end

end

# How do we make method1 available to class Charlie? Please make sure you test your code before you post your answer.
=end
module Mixin
  extend self

  def method1
    'method1'
  end
end

class Charlie
  include Mixin
  extend Mixin
end

require 'minitest/autorun'
class MixinTest < Minitest::Test

  def test_module_method
    assert_equal 'method1', Mixin.method1
  end

  def test_class_method
    assert_equal 'method1', Charlie.method1
  end

  def test_instance_method
    charlie = Charlie.new
    assert_equal 'method1', charlie.method1
  end
end