testing nested route in functional tests

I have a nested route:

resources :stories do
  resources :comments
end

this is my create method in controller:

def create
  @story = Story.find(params[:story_id])
  @comment = @story.comments.build(params[:comment])
  @comments = @story.comments.all

  respond_to do |format|
    if @comment.save
      format.html { redirect_to @story, notice: t('controllers.comments.create.flash.success') }
      format.json { render json: @comment, status: :created, location: @comment }
    else
      format.html { render template: "stories/show" }
      format.json { render json: @comment.errors, status: :unprocessable_entity }
    end
  end
end

And here is it's test:

setup do
  @comment = comments(:one)
  @story = stories(:one)
end

  ....

test "should create comment" do
  assert_difference('Comment.count') do
    post :create, :story_id => @story.id, comment: { content: @comment.content, name: @comment.name, email: @comment.email }
  end

  assert_redirected_to @story_path
end

that ends up with this error:

1) Failure:
test_should_create_comment(CommentsControllerTest) [/home/arach/workspace/Web/ruby/nerdnews/test/functional/comments_controller_test.rb:25]:
Expected response to be a redirect to <http://test.host/stories/980190962/comments> but was a redirect to <http://test.host/stories/980190962>

I don't know why the test expect to redirect to stories/:id/comments. I tried other things like story_comment_path but it didn't help either. story_path without @ also ends up with another error:

ActionController::RoutingError: No route matches {:action=>"show", :controller=>"stories"}

same error happens for story_path, :story_id => @story.id. Any idea why this happens?