Custom Include/Extend

# created by Huynh Quang Thao
# on 02/04/2017
require 'test/unit'

# ------------------------------------------------------------
# implementation
class Class
  # def custom_extend(module_name)
  #   module_name.methods(false).each do |method|
  #     define_singleton_method(method) do |*args, &block|
  #       module_name.send(method, *args, &block)
  #     end
  #   end
  # end

  def custom_include(module_)
    # for public and protected methods:
    module_.instance_methods(include_super=false).each do |meth_name|
      meth = module_.instance_method(meth_name)
      define_method(meth_name) do |*args, &block|
        meth.bind(self).call(*args, &block)
      end
    end

    # for private methods:
    module_.private_instance_methods(include_super=false).each do |meth_name|
      meth = module_.instance_method(meth_name)
      define_method(meth_name) do |*args, &block|
        meth.bind(self).call(*args, &block)
      end
      private :"#{meth_name}"
    end
  end

  def custom_extend(module_)
    singleton_class.custom_include module_
  end
end

# -------------------------------------------------------------
# Demonstration
module SimpleModule
  def hello_world
    'Hello World'
  end

  def hello_name
    "Hello to #{@instance_name}"
  end

  def hello_with_name(name)
    res = block_given? ? yield : ''
    "Hello to #{res}.#{name}"
  end

  private
  def private_hello
    'Hello privately !!!'
  end
end

class SimpleClass
  custom_include SimpleModule
  custom_extend  SimpleModule

  @instance_name = 'Thao'

  def internal_hello
    private_hello
  end
end

puts SimpleClass.hello_world
puts SimpleClass.hello_name

puts SimpleClass.new.hello_world
puts SimpleClass.new.hello_name
puts SimpleClass.new.hello_with_name('thao')

# -----------------------------------------------------------------
# Testing
class TestUsing < Test::Unit::TestCase
  def test_custom_include_simple
    message = SimpleClass.new.hello_world
    assert message == 'Hello World'
  end

  def test_custom_include_param
    message = SimpleClass.new.hello_with_name('Superman')
    assert message == 'Hello to .Superman'
  end

  def test_custom_include_block
    message = SimpleClass.new.hello_with_name('Superman') do
      'Mr'
    end
    assert message == 'Hello to Mr.Superman'
  end

  def test_custom_include_private
    assert_raise NoMethodError do
      SimpleClass.new.private_hello
    end

    message = SimpleClass.new.internal_hello
    assert message == 'Hello privately !!!'
  end

  def test_custom_extend_simple
    message = SimpleClass.hello_world
    assert message == 'Hello World'
  end

  def test_custom_extend_shared_scope
    message = SimpleClass.hello_name
    assert message == 'Hello to Thao'
  end

  def custom_extend_param
    message = SimpleClass.hello_with_name('Supergirl')
    assert message == 'Hello to .Supergirl'
  end

  def test_custom_extend_block
    message = SimpleClass.hello_with_name('Supergirl') do
      'Miss'
    end
    assert message == 'Hello to Miss.Supergirl'
  end

  def test_custom_extend_private
    assert_raise NoMethodError do
      SimpleClass.private_hello
    end
  end
end

TestUsing.new("test extend/include")