Can I use has_many :through and :dependent => destroy together?-Collection of common programming errors

I’m trying to run a functional test on my PollsController and keep getting this error:

block in assert_valid_keys': Unknown key: through (ArgumentError)

I’m wondering if its because I have a dependent destroy on the Question model and a has_many relationship ship through it to sms. Any advice? Thanks!!

Here’s the Poll model

class Poll < ActiveRecord::Base
  attr_accessible :description, :end_time, :start_time, :title, :user_id, :questions_attributes, :is_live

  belongs_to :user
  has_many :questions, :dependent => :destroy
  # This is the pluralized form of sms, it's not smss
  has_many :sms, :through => :questions 
  has_many :feedbacks

  accepts_nested_attributes_for :questions, :allow_destroy => true

Question model

class Question < ActiveRecord::Base
  attr_accessible :poll_id, :title, :answers_attributes

  belongs_to :poll
  has_many :answers, :dependent => :destroy
  # THis is the plularized form of sms, it's not smss
  has_many :sms
                                          #If someone creates a form with a blank question field at the end, this will prevent it from being rendered on teh show page
  accepts_nested_attributes_for :answers, :allow_destroy => true

end

Originally posted 2013-11-09 23:22:58.