TDDing the feed parser stuff

Author: Matt Swanson

.rspec

@@ -0,0 +1 @@
+--colour

Gemfile

@@ -8,6 +8,8 @@ gem "sinatra-contrib", github: "sinatra/sinatra-contrib"
 gem "rake"
 gem "delayed_job_active_record"
 
+gem "feedzirra", github: "pauldix/feedzirra"
+
 group :production do
   gem "unicorn"
   gem "pg"

Gemfile.lock

@@ -1,3 +1,13 @@
+GIT
+  remote: git://github.com/pauldix/feedzirra.git
+  revision: 80cd35766e40ee3058db1c5c0c25448baeea4212
+  specs:
+    feedzirra (0.2.0.rc2)
+      curb (~> 0.8.1)
+      loofah (~> 1.2.1)
+      nokogiri (~> 1.5.3)
+      sax-machine (~> 0.2.0.rc1)
+
 GIT
   remote: git://github.com/sinatra/sinatra-contrib.git
   revision: 639acf8e8aec660cae5e4bfb5ed3d03132ed98e5
@@ -28,6 +38,7 @@ GEM
     backports (3.3.0)
     builder (3.0.4)
     coderay (1.0.9)
+    curb (0.8.3)
     delayed_job (3.0.5)
       activesupport (~> 3.0)
     delayed_job_active_record (0.4.4)
@@ -37,8 +48,11 @@ GEM
     eventmachine (1.0.3)
     i18n (0.6.1)
     kgio (2.8.0)
+    loofah (1.2.1)
+      nokogiri (>= 1.4.4)
     method_source (0.8.1)
     multi_json (1.7.2)
+    nokogiri (1.5.9)
     pg (0.15.0)
     pry (0.9.12)
       coderay (~> 1.0.5)
@@ -62,6 +76,8 @@ GEM
     rspec-expectations (2.13.0)
       diff-lcs (>= 1.1.3, < 2.0)
     rspec-mocks (2.13.0)
+    sax-machine (0.2.0.rc1)
+      nokogiri (~> 1.5.2)
     shotgun (0.9)
       rack (>= 1.0)
     sinatra (1.4.2)
@@ -87,6 +103,7 @@ PLATFORMS
 
 DEPENDENCIES
   delayed_job_active_record
+  feedzirra!
   pg
   pry
   rack-test

app/repositories/feed_repository.rb

@@ -0,0 +1,6 @@
+class FeedRepository
+  def self.update_last_fetched(feed, timestamp)
+    feed.last_fetched = timestamp
+    feed.save
+  end
+end

app/repositories/story_repository.rb

@@ -0,0 +1,5 @@
+class StoryRepository
+  def self.add(entry, feed)
+
+  end
+end

app/tasks/fetch_feed.rb

@@ -0,0 +1,29 @@
+require "feedzirra"
+require_relative "../repositories/story_repository"
+require_relative "../repositories/feed_repository"
+
+class FetchFeed
+  def initialize(feed, feed_parser = Feedzirra::Feed)
+    @feed = feed
+    @parser = feed_parser
+  end
+
+  def fetch
+    result = @parser.fetch_and_parse(@feed.url)
+
+    unless result.last_modified < @feed.last_fetched
+      FeedRepository.update_last_fetched(@feed, result.last_modified)
+
+      result.entries.each do |entry|
+        StoryRepository.add(entry, @feed) if is_new?(entry)
+      end
+    end
+
+    result
+  end
+
+  private
+  def is_new?(entry)
+    entry.published > @feed.last_fetched
+  end
+end

app/tasks/fetch_feeds.rb

@@ -0,0 +1,13 @@
+require_relative "fetch_feed"
+
+class FetchFeeds
+  def initialize(feeds)
+    @feeds = feeds
+  end
+
+  def fetch_all
+    @feeds.each do |feed|
+      FetchFeed.new(feed).fetch
+    end
+  end
+end

spec/spec_helper.rb

@@ -0,0 +1,15 @@
+ENV['RACK_ENV'] = 'test'
+
+require "rspec"
+require "rack/test"
+require "pry"
+require "ostruct"
+require "date"
+
+RSpec.configure do |config|
+  config.include Rack::Test::Methods
+end
+
+def app_require(file)
+  require File.expand_path(File.join("app", file))
+end

spec/tasks/fetch_feed_spec.rb

@@ -0,0 +1,52 @@
+require "spec_helper"
+app_require "tasks/fetch_feed"
+
+class Feed < OpenStruct; end;
+
+describe FetchFeed do
+  let (:daring_fireball) {
+    Feed.new(name: "Daring Fireball", url: "http://daringfireball.net/index.xml", last_fetched: Time.new(2013, 4, 5))
+  }
+
+  describe "#fetch" do
+    it "fetches the feed" do
+      result = FetchFeed.new(daring_fireball).fetch
+      result.title.should eq "Daring Fireball"
+      result.entries.first.author.should eq "John Gruber"
+    end
+
+    context "when no new posts have been added" do
+      it "should not add any new posts" do
+        fake_feed = stub(last_modified: Time.new(2012, 12, 31))
+        parser = stub(fetch_and_parse: fake_feed)
+
+        StoryRepository.should_not_receive(:add)
+
+        FetchFeed.new(daring_fireball, parser).fetch
+      end
+    end
+
+    context "when new posts have been added" do
+      let(:now) { Time.now }
+      let(:new_story){ stub(published: now + 1) }
+      let(:old_story) { stub(published: Time.new(2009, 4, 20)) }
+
+      let(:fake_feed) { stub(last_modified: now, entries: [new_story, old_story]) }
+      let(:fake_parser) { stub(fetch_and_parse: fake_feed) }
+
+      it "should only add posts that are new" do
+        StoryRepository.should_receive(:add).with(new_story, daring_fireball)
+        StoryRepository.should_not_receive(:add).with(old_story, daring_fireball)
+
+        FetchFeed.new(daring_fireball, fake_parser).fetch
+      end
+
+      it "should update the last fetched time for the feed" do
+        FeedRepository.should_receive(:update_last_fetched)
+          .with(daring_fireball, now)
+
+        FetchFeed.new(daring_fireball, fake_parser).fetch
+      end
+    end
+  end
+end