[rspec-users] How To Spec Controllers with Finders

[s.ross]

Given this code (which renders rjs), I'm faced with the fixture- 
driven way of spec-ing or mocking. How the heck to you mock this so  
the code at line (2) and (4) work right? I'm still struggling with  
mocks but it seems like this can be done. Forgive the naivety of this  
question.

1.  def change_quantity
2.    @line_item = LineItem.find_by_id(params[:id])
3.    unless @line_item.nil?
4.      @line_item.update_attribute(:quantity, params[:quantity])
5.      @extension_id = "extension#{params[:id]}"
6.    end
7.  end

Thanks