How i write the respec in this situation??

Hi all guys!im new in rails!
i have a forum,have_many topics,and the topic also has_many
replies.Now i want to write the respec for the repliescontroller:

describe RepliesController do
  controller_name :repies
  describe "All Requests",:share=>true do
    before do
      @forum = mock_model(Forum,:id=>'1')
      @topic = mock_model(Topic,:id=>'1',:forum =>@forum)
      @reply = mock_model(Reply,:topic => @topic,:save=>true)

      @params = {
        :topic_id =>,
        :forum_id =>,
        :title => 'Ragnarok',
        :body => 'ragnarokrangarkratnonfgdsakl'

    def do_post
      post :create,:reply =>@params

    it "should call Reply modl with new values" do
    it "should add reply to the topic" do
      response.should redirect_to([@forum,@topic])


No route matches Error!
i have no idea for rspec!!