[rspec-users] how to catch a missing image (rspec-rails)

Pat Maddox pergesu at gmail.com
Fri Oct 3 01:20:10 EDT 2008

Evan Dorn <lists at ruby-forum.com> writes:

> I want to make sure all external resources called for by my views (like
> images) actually exist.  How do I write an rspec that will fail when an
> image included on the page isn't present?
> For example, let's say in application.html.erb, I include <img
> src="/images/mylogo.png">, but that file doesn't exist (say it's
> actually /images/mylogo.jpg).
> When this is run on the server, the image won't appear, and the server
> log will show an error like this:
>  >> ActionController::RoutingError (No route matches
> "/images/mylogo.png" with
>  >> {:method=>:get}):
> However, views tests like response.should have_tag(img[src=/mylogo.png/)
> won't catch it, because the tag will be there.    controllers tests
> (with integrate_views on) for response.should be_success,
> render_template won't catch it because the page itself was a success and
> rendered the template.
> But an error was thrown during a second connection to the server,
> because the image file didn't exist ... there must be a way for any such
> failures.  How?

Hi Evan,

Can you rely on the convention that images are under RAILS_ROOT/public?
If so, you could do a little translucent-box testing.  Maybe you could
use hpricot to get all the image elements and check their referenced
file's existence.

# I'm just BSing the hpricot
hpricot("doc/img") do |element|
  element.attr('src').should be_existing_resource 

Where be_existing_resource is a custom matcher with a simple
implementation of

def matches?(actual)
  File.exists?(File.expand_path(RAILS_ROOT + actual))

(simple enough for a simple matcher, even)

This should give you a good deal of confidence without any hassle.


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