DEV: Amend suggested topics when user has experimental new new view (#21879)

What does this change do?

Suggested topics by default are ordered in the following way:

1. Unread topics in current category of topic that is being viewed
2. Unread topics in other categories
3. New topics in current category of topics that is being viewed
4. New topics in other categories
5. Random topics

With the experimental new new view, we want to remove the concept of
read and new so that new order is as such:

1. Topics created by the current user with posts that the user has not
   read ordered by topic's bumped date
2. Topics in current category of topic with posts that the user has not
   read ordered by topic's bumped date
3. Topics in other categories with posts that the user has not read
   ordered by topic's bumped date
4. Random topics ordered by topic's bumped date

lib/topic_query.rb

@@ -235,17 +235,27 @@ class TopicQuery
           builder.add_results(unread_messages(pm_params.merge(count: builder.results_left)))
         end
       else
-        builder.add_results(
-          unread_results(
-            topic: topic,
-            per_page: builder.results_left,
-            max_age: SiteSetting.suggested_topics_unread_max_days_old,
-          ),
-          :high,
-        )
+        if @user.new_new_view_enabled?
+          builder.add_results(
+            new_and_unread_results(
+              topic:,
+              per_page: builder.results_left,
+              max_age: SiteSetting.suggested_topics_unread_max_days_old,
+            ),
+          )
+        else
+          builder.add_results(
+            unread_results(
+              topic: topic,
+              per_page: builder.results_left,
+              max_age: SiteSetting.suggested_topics_unread_max_days_old,
+            ),
+            :high,
+          )
 
-        unless builder.full?
-          builder.add_results(new_results(topic: topic, per_page: builder.category_results_left))
+          unless builder.full?
+            builder.add_results(new_results(topic: topic, per_page: builder.category_results_left))
+          end
         end
       end
     end
@@ -581,6 +591,7 @@ class TopicQuery
         base,
         treat_as_new_topic_start_date: @user.user_option.treat_as_new_topic_start_date,
       )
+
     new_results = remove_muted(new_results, @user, options)
     new_results = remove_dismissed(new_results, @user)
 

spec/lib/topic_query_spec.rb

@@ -1365,7 +1365,7 @@ RSpec.describe TopicQuery do
     end
   end
 
-  describe "suggested_for" do
+  describe "#list_suggested_for" do
     def clear_cache!
       Discourse.redis.keys("random_topic_cache*").each { |k| Discourse.redis.del k }
     end
@@ -1433,12 +1433,139 @@ RSpec.describe TopicQuery do
       end
     end
 
+    context "when logged in and user is part of the `experimental_new_new_view_groups` site setting groups" do
+      fab!(:group) { Fabricate(:group) }
+      fab!(:topic) { Fabricate(:topic) }
+
+      before do
+        SiteSetting.experimental_new_new_view_groups = group.name
+        group.add(user)
+      end
+
+      after { clear_cache! }
+
+      context "when there are no new topics for user" do
+        it "should return random topics excluding topics that are muted by user and not older than `suggested_topics_max_days_old` site setting" do
+          topic2 = Fabricate(:topic, user: user)
+          topic3 = Fabricate(:topic, user: user)
+          topic4 = Fabricate(:topic, user: user, created_at: 8.days.ago)
+          topic5 = Fabricate(:topic).tap { |t| TopicNotifier.new(t).mute!(user) }
+
+          SiteSetting.suggested_topics_max_days_old = 7
+
+          expect(topic_query.list_suggested_for(topic).topics.map(&:id)).to eq(
+            [topic3.id, topic2.id],
+          )
+        end
+      end
+
+      context "when there are new topics for user" do
+        fab!(:category) { Fabricate(:category) }
+        fab!(:category2) { Fabricate(:category) }
+
+        fab!(:topic_in_category_that_user_created_and_has_partially_read) do
+          Fabricate(:topic, user: user, category:).tap do |t|
+            first_post = Fabricate(:post, topic: t)
+            second_post = Fabricate(:post, topic: t)
+
+            TopicUser.change(
+              user.id,
+              t.id,
+              notification_level: TopicUser.notification_levels[:tracking],
+            )
+
+            TopicUser.update_last_read(user, t.id, second_post.post_number - 1, 1, 1)
+          end
+        end
+
+        fab!(:topic_in_category2_that_user_created_and_has_partially_read) do
+          Fabricate(:topic, user: user, category: category2).tap do |t|
+            first_post = Fabricate(:post, topic: t)
+            second_post = Fabricate(:post, topic: t)
+
+            TopicUser.change(
+              user.id,
+              t.id,
+              notification_level: TopicUser.notification_levels[:tracking],
+            )
+
+            TopicUser.update_last_read(user, t.id, second_post.post_number - 1, 1, 1)
+          end
+        end
+
+        fab!(:topic_in_category_that_user_has_partially_read) do
+          Fabricate(:topic, category:).tap do |t|
+            first_post = Fabricate(:post, topic: t)
+            second_post = Fabricate(:post, topic: t)
+
+            TopicUser.change(
+              user.id,
+              t.id,
+              notification_level: TopicUser.notification_levels[:tracking],
+            )
+
+            TopicUser.update_last_read(user, t.id, second_post.post_number - 1, 1, 1)
+          end
+        end
+
+        fab!(:topic_in_category2_that_user_has_partially_read) do
+          Fabricate(:topic, category: category2).tap do |t|
+            first_post = Fabricate(:post, topic: t)
+            second_post = Fabricate(:post, topic: t)
+
+            TopicUser.change(
+              user.id,
+              t.id,
+              notification_level: TopicUser.notification_levels[:tracking],
+            )
+
+            TopicUser.update_last_read(user, t.id, second_post.post_number - 1, 1, 1)
+          end
+        end
+
+        fab!(:topic_in_category_that_user_has_not_read) { Fabricate(:topic, category:) }
+        fab!(:topic_in_category2_that_user_has_not_read) { Fabricate(:topic, category: category2) }
+
+        before { topic.update!(category:) }
+
+        it "should return new topics for user ordered by topics that user has created first, in the same category as the topic and then topic's bumped at" do
+          expect(
+            topic_query.list_suggested_for(topic, include_random: false).topics.map(&:id),
+          ).to eq(
+            [
+              topic_in_category_that_user_created_and_has_partially_read.id,
+              topic_in_category2_that_user_created_and_has_partially_read.id,
+              topic_in_category_that_user_has_not_read.id,
+              topic_in_category_that_user_has_partially_read.id,
+              topic_in_category2_that_user_has_not_read.id,
+            ],
+          )
+
+          SiteSetting.suggested_topics = 6
+
+          expect(
+            topic_query.list_suggested_for(topic, include_random: false).topics.map(&:id),
+          ).to eq(
+            [
+              topic_in_category_that_user_created_and_has_partially_read.id,
+              topic_in_category2_that_user_created_and_has_partially_read.id,
+              topic_in_category_that_user_has_not_read.id,
+              topic_in_category_that_user_has_partially_read.id,
+              topic_in_category2_that_user_has_not_read.id,
+              topic_in_category2_that_user_has_partially_read.id,
+            ],
+          )
+        end
+      end
+    end
+
     context "when logged in" do
       def suggested_for(topic)
         topic_query.list_suggested_for(topic)&.topics&.map { |t| t.id }
       end
 
       let(:topic) { Fabricate(:topic) }
+
       let(:suggested_topics) do
         tt = topic
         # lets clear cache once category is created - working around caching is hard