DEV: use structured data in topic-list for referencing only (#16235)

This simplifies the ItemList to only be a point of reference to the
actual DiscussionForumPosting objects.

See "Summary page": https://developers.google.com/search/docs/advanced/structured-data/carousel?hl=en#summary-page

Co-authored-by: Bianca Nenciu <nenciu.bianca@gmail.com>

spec/views/list/list.erb_spec.rb

@@ -4,6 +4,7 @@ require "rails_helper"
 
 RSpec.describe "list/list.erb" do
   fab!(:category) { Fabricate(:category) }
+  fab!(:topic) { Fabricate(:topic) }
 
   it "add nofollow to RSS alternate link for category" do
     view.stubs(:include_crawler_content?).returns(false)
@@ -15,4 +16,16 @@ RSpec.describe "list/list.erb" do
     expect(view.content_for(:head)).to match(/<link rel="alternate nofollow" type="application\/rss\+xml" title="[^"]+" href="https:\/\/www.example.com\/test\.rss" \/>/)
   end
 
+  it "adds sturctured data" do
+    view.stubs(:include_crawler_content?).returns(true)
+    topic.posters = []
+    assign(:list, OpenStruct.new(topics: [topic]))
+
+    render template: 'list/list', formats: []
+
+    topic_list = Nokogiri::HTML5::fragment(rendered).css('.topic-list')
+    first_item = topic_list.css('[itemprop="itemListElement"]')
+    expect(first_item.css('[itemprop="position"]')[0]['content']).to eq('1')
+    expect(first_item.css('[itemprop="url"]')[0]['href']).to eq(topic.url)
+  end
 end