add named_scopes to mock_models

scopify.rb

  def scopify(model_class, *scopes)
    mocks = [model_class]
    scopes.each do |scope|
      mocks << mock(scope.to_s)
    end
    mocks.each do |mock|
      mocks.delete_if { |m| m == mock || m == model_class }.each do |m|
        mock.stub!(m.instance_variable_get(:@name)).and_return(model_class)
      end
    end
  end

# so that this spec:

@post = mock_model(Post)
scopify(Post, :published, :tagged_with, :by_date)
Post.stub!(:paginate).and_return([@post])

# works with:
@posts = Post.published.tagged_with("commentary", :on => :category).by_date.paginate(:page => params[:page], :per_page => 50)