Fix atom feed test

Requesting the atom feed through Chrome gives us a HTML
response. Instead we make a direct request and parse it using Ruby’s
RSS library.

test/integration/travel_advice_atom_feed_test.rb

@@ -1,41 +1,52 @@
 require 'test_helper'
 
+require 'nokogiri/html'
+require 'open-uri'
+require 'rss'
+
 class TravelAdviceAtomFeed < ActionDispatch::IntegrationTest
   setup do
-    setup_and_visit_travel_advice_atom_feed('full-country')
+    setup_and_parse_travel_advice_atom_feed('full-country')
     @base_path = @content_item['base_path']
     @updated_at = DateTime.parse(@content_item["public_updated_at"]).rfc3339
   end
 
   test "it sets the alternative link correctly" do
-    assert page.has_css?("feed>link[rel='alternate'][href$='#{@base_path}']")
+    alternate_link = @feed.links.find { |link| link.rel == 'alternate' }
+    assert alternate_link.href.ends_with?(@base_path)
   end
 
   test "it sets the entry's id to the url concatenated with updated_at" do
-    id = page.find("feed>entry>id").text(:all)
+    id = @feed.items.first.id.content
     assert id.end_with?("#{@base_path}##{@updated_at}")
   end
 
   test "it sets the entry's title correctly" do
-    title = page.find("feed>entry>title").text(:all)
+    title = @feed.items.first.title.content
     assert_equal title, @content_item['title']
   end
 
   test "it sets the entry's summary correctly" do
-    summary = page.find("feed>entry>summary").text(:all)
-    assert_equal summary, @content_item['details']['change_description'].strip
+    summary = Nokogiri::HTML::fragment(@feed.items.first.summary.content)
+    assert_equal summary.text.strip, @content_item['details']['change_description'].strip
   end
 
   test "it sets the entry's updated correctly" do
-    updated = page.find("feed>entry>updated").text(:all)
+    updated = @feed.items.first.updated.content
     assert_equal updated, @updated_at
   end
 
-  def setup_and_visit_travel_advice_atom_feed(name)
-    example = get_content_example_by_schema_and_name('travel_advice', name)
-    @content_item = example.tap do |item|
-      content_store_has_item(item["base_path"], item.to_json)
-      visit "#{item['base_path']}.atom"
-    end
+  def setup_and_parse_travel_advice_atom_feed(name)
+    @content_item = get_content_example_by_schema_and_name('travel_advice', name)
+
+    uri = URI::HTTP.build(
+      host: Capybara.current_session.server.host,
+      port: Capybara.current_session.server.port,
+      path: "#{@content_item['base_path']}.atom"
+    )
+
+    content_store_has_item(@content_item["base_path"], @content_item.to_json)
+
+    @feed = RSS::Parser.parse(uri.read)
   end
 end