feed.rb

class Feed
  attr_accessor :feed
  
  def initialize(url)
    Feedzirra::Feed.fetch_and_parse(url, {:on_success => lambda {|feed| @feed = feed[1] }, :on_failure => lambda {|url, response_code, response_header, response_body| raise "Feed failed to parse: http response code #{response_code}"}, :timeout => 4800})
  end
  
  def sanitize!
    @feed.sanitize_entries!
  end
  
  def tweetable_entries(time_span = nil)
    time_span ||= Time.now - 86400
    @feed.entries.select { |entry| (entry.published || Time.now) >= time_span}
  end
  
end

feed_spec.rb

require File.dirname(__FILE__) + '/spec_helper'

describe Feed do
  
  it "should fetch and parse the feed" do
    Feedzirra::Feed.should_receive(:fetch_and_parse).with("http://www.test.com/test.atom", kind_of(Hash)).and_return(load_sample("jotly.atom"))
    Feed.new("http://www.test.com/test.atom")
  end
  
  describe "already created" do
    
    before do
      Feedzirra::Feed.stub!(:fetch_and_parse).and_return(parsed_atom_feed)
      @feed = Feed.new("http://www.test.com/test.atom")
    end
    
    it "should find tweetable entries" do
      puts @feed.inspect
      entries = @feed.tweetable_entries(Time.utc(2008, 11, 1))
      entries.size.should == 1
    end
    
    it "should find no tweetable entries when there are none" do
      entries = @feed.tweetable_entries(Time.now)
      entries.should be_blank
    end
    
  end

end

spec_helper.rb

def load_sample(filename)
  File.read("#{File.dirname(__FILE__)}/feeds/#{filename}")
end

def sample_atom_feed
  load_sample("jotly.atom")
end

def parsed_atom_feed
  Feedzirra::Feed.parse(sample_atom_feed)
end