Validating RSS Feeds with RSpec

Rick DeNatale — Fri, 08 Feb 2008 10:38:00 -0500

One of my current Rails projects involves generating an RSS feed. While I was working on this the other night, it seemed to be working, so I deployed it to the staging server. Everything looked fine. If I fetched it with Firefox, the browser offered to let me subscribe to the feed with Google Reader, and if I used Safari I'd see a nice view of the feed just like I expected.

So I sent a note via our campfire to check it out, and a colleague replied that his Safari was saying that it was in an invalid format.

So I went to the W3 RSS Feed Validation Service and worked through the validation issues, after which his browser was as happy as mine.

Of course, having been through that, I wanted to make sure that RSS validation was covered in the specs for the project.

I went looking for an existing RSpec matcher, and found a matcher to validate XHTML but nothing for RSS.

I then found the feedvalidator gem which provides a Ruby interface to the SOAP interface to the W3 feed validator. You would think that W3 would be providing a REST interface! The gem already provides assertions for use with Test::Unit, so I just built an RSpec matcher.

class BeValidFeed
  require 'feed_validator'
  require 'tmpdir'
  require 'md5'

  def matches?(response)
    return true if validity_checks_disabled?
    v = W3C::FeedValidator.new()
    fragment = response.body
    filename = File.join Dir::tmpdir, 'feed.' + MD5.md5(fragment).to_s
    begin
      response = File.open filename do |f| Marshal.load(f) end
      v.parse(response)
  	rescue   
      unless v.validate_data(fragment)
        @failure = " could not access w3 validator to validate the feed."
        return false
      end
      File.open filename, 'w+' do |f| Marshal.dump v.response, f end
  	end
    v.valid?   
  end

  def description
    "be valid xhtml"
  end

  def failure_message
   @failure || " expected xhtml to be valid, but validation produced these errors:\n #{@message}"
  end

  def negative_failure_message
    " expected to not be valid, but was (missing validation?)"
  end

  private
    def validity_checks_disabled?
      ENV["NONET"] == 'true'
    end
end

def be_valid_feed
  BeValidFeed.new
end

I saved this as spec/be_valid_feed.rb

And in a view or controller spec, I can include this file, and test a response with:

response.should be_valid_feed

If you use this in a controller spec, you will need to tell RSpec to integrate_views, or you won't have much of a feed to check. If you use nested example groups, integrate_views needs to be inside the inner group.

"Validating RSS Feeds with RSpec" by Edgar

Sat, 09 Feb 2008 17:11:44 -0500

Great ! If I got time I’ll add the matcher to feedvalidator

"Validating RSS Feeds with RSpec" by Rick DeNatale

Sat, 09 Feb 2008 15:11:48 -0500

Tim -

Yes generally I prefer Atom, however for this gig the rss feed is for consumption by iTunes, and as far as I know that requires RSS.

"Validating RSS Feeds with RSpec" by Ben Mabey

Fri, 08 Feb 2008 13:02:56 -0500

Thanks Rick! This will be handy next time I do a feed.

"Validating RSS Feeds with RSpec" by Tim Bray

Fri, 08 Feb 2008 12:49:56 -0500

Next time, generate Atom 1.0 instead. The validator messages are way more helpful and you get to dodge a bunch of corner cases with enclosures and summaries and categories and so on.

Talk Like A Duck: Validating RSS Feeds with RSpec

Validating RSS Feeds with RSpec

"Validating RSS Feeds with RSpec" by Edgar

"Validating RSS Feeds with RSpec" by Rick DeNatale

"Validating RSS Feeds with RSpec" by Ben Mabey

"Validating RSS Feeds with RSpec" by Tim Bray