[rspec-users] [Rails] render_to_string in a controller fails under RSpec

Joel Young skizzybiz at gmail.com
Thu Nov 5 17:23:56 EST 2009

I'm using render_to_string in a controller to send some JSON data with
an HTML fragment. Unfortunately, it seems that rspec-rails breaks that
by intercepting render and simply recording that a render was called.
Using rspec-rails and rspec versions 1.2.9, I've tracked it down to
lib/spec/rails/example/controller_example_group.rb:181 -- since it's
calling record_render, it returns a Fixnum, so instead of an HTML
fragment, I get "1". I've confirmed that if I add a call to "super" on
the next line, it does what I want. Obviously that would be bad for
other reasons, though.

Is there a workaround for this? Is there a better way to get an HTML
fragment included in the JSON? Using an RJS template won't work, since
it wraps my JSON object in an exception handling block.

For reference, here's the controller action that calls

  def changed
    unless params[:since]
      render :status => :bad_request
    respond_to do |format|
      format.js do
        @changed = Event.changed_since(params[:since]).collect do |
            :id => dom_id(event),
            :sidebar_html => render_to_string(:partial =>
"history_item", :object => event)
        render :json => @changed

And here is the relevant part of the controller spec:

      it "should return the sidebar HTML for the event" do
        get :changed, :since => @time
        json = JSON.parse(response.body)
        json.should have(1).event
        response.body = json.first["sidebar_html"]
        response.should include_text("TestApp r1234")

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