Rails test: test image_tag on view

I'm writing the view tests and i want to test an image

<%= image_tag "icon.png", class: "img-responsive" %>

So i made this test, but is not working

it 'app logo' do
  render
  assert_select 'img[src=?]', asset_path('icon.png')
end

What could be the problem? Is this the correct why to test it with rspec?