ruby on rails - rspec: ignoring format while testing a view? -

i'm writing test views. happen have html , json views 1 action, , didn't figured out how can force rspec use given format.

currently minimized code following:

# cat spec/views/services/index.json.jbuilder_spec.rb require 'spec_helper'  describe "services/index"   let(:services) { 3.times.map { factorygirl.create(:service) } }   before(:each) { assign(:services, services) }   let(:resp)       render template: 'services/index', format: :json # note format here       json.parse(response.body, simbolize_names: true)     end    it("should array") { resp.should be_kind_of(array) } end 

but stills rendering html code. i'm getting error

failure/error: json.parse(response.body, simbolize_names: true) json::parsererror: 757: unexpected token @ '<h1>listing services</h1> [cut rest of html] 

my json view simple

# cat app/views/services/index.json.jbuilder json.array! @services, *service.json_attributes 

and first 5 lines of html view is

# cat app/views/services/index.html.haml  | head -5 %h1 listing services  %table   %tr     %th logo 

if try pass format in render template, like

render template: 'services/index.json' 

i got following:

deprecation warning: passing template handler in template name deprecated. can remove handler name or pass render  

my rspec version 2.13.1, running on ruby 2.0.

just curious:
render template: 'services/index', formats: :json work well?
notice formats s in end.