Isolated and not working

my_spec.rb

require 'my'

module MyHelper
  def default_config
    config = Hash.new
    config[:stuff] = :stuff
  end
end

module My
  describe My do
    include MyHelper

    before :each do
      let(:config) {
        default_config
      }
    end

    describe "Stuff" do
      before :all do
        config[:stuff] = Object.new
      end
      it "wasn't working" do
        puts "weee"
      end
    end

    it "might work" do
      config[:stuff] = Object.new
    end
  end
end