clone_module_incluing_classes.rb

# A solution to https://gist.github.com/792624/0df60239d007782c366445f6d86700382386716b

class Object
  def clone_constants_from(victim)
    victim.constants.each do |constant|
      send(:remove_const, constant)
      const_set(constant, victim.const_get(constant).clone)
      victim.const_get(constant).clone_constants_from(const_get(constant))
    end
  end
end

module Foo
  class Bar
  end

  class Baz
    class Bzz
    end
  end
end

Woo = Foo.clone
Woo.clone_constants_from(Foo)

puts Foo.object_id == Woo.object_id
puts Foo::Bar.object_id == Woo::Bar.object_id
puts Foo::Baz.object_id == Woo::Baz.object_id
puts Foo::Baz::Bzz.object_id == Woo::Baz::Bzz.object_id