FEATURE: include most popular tag in page title for webcrawlers of tagged uncategorized topics

lib/topic_view.rb

@@ -142,8 +142,12 @@ class TopicView
 
   def page_title
     title = @topic.title
-    if SiteSetting.topic_page_title_includes_category && @topic.category_id != SiteSetting.uncategorized_category_id && @topic.category_id && @topic.category
-      title += " - #{topic.category.name}"
+    if SiteSetting.topic_page_title_includes_category
+      if @topic.category_id != SiteSetting.uncategorized_category_id && @topic.category_id && @topic.category
+        title += " - #{@topic.category.name}"
+      elsif SiteSetting.tagging_enabled && @topic.tags.exists?
+        title += " - #{@topic.tags.order('tags.topic_count DESC').first.name}"
+      end
     end
     title
   end

spec/components/topic_view_spec.rb

@@ -428,5 +428,73 @@ describe TopicView do
       end
     end
   end
+
+  context "page_title" do
+    let(:tag1) { Fabricate(:tag) }
+    let(:tag2) { Fabricate(:tag, topic_count: 2) }
+
+    subject { TopicView.new(topic.id, coding_horror).page_title }
+
+    context "uncategorized topic" do
+      context "topic_page_title_includes_category is false" do
+        before { SiteSetting.topic_page_title_includes_category = false }
+        it { should eq(topic.title) }
+      end
+
+      context "topic_page_title_includes_category is true" do
+        before { SiteSetting.topic_page_title_includes_category = true }
+        it { should eq(topic.title) }
+
+        context "tagged topic" do
+          before { topic.tags << [tag1, tag2] }
+
+          context "tagging enabled" do
+            before { SiteSetting.tagging_enabled = true }
+
+            it { should start_with(topic.title) }
+            it { should_not include(tag1.name) }
+            it { should end_with(tag2.name) } # tag2 has higher topic count
+          end
+
+          context "tagging disabled" do
+            before { SiteSetting.tagging_enabled = false }
+
+            it { should start_with(topic.title) }
+            it { should_not include(tag1.name) }
+            it { should_not include(tag2.name) }
+          end
+        end
+      end
+    end
+
+    context "categorized topic" do
+      let(:category) { Fabricate(:category) }
+
+      before { topic.update_attributes(category_id: category.id) }
+
+      context "topic_page_title_includes_category is false" do
+        before { SiteSetting.topic_page_title_includes_category = false }
+        it { should eq(topic.title) }
+      end
+
+      context "topic_page_title_includes_category is true" do
+        before { SiteSetting.topic_page_title_includes_category = true }
+        it { should start_with(topic.title) }
+        it { should end_with(category.name) }
+
+        context "tagged topic" do
+          before do
+            SiteSetting.tagging_enabled = true
+            topic.tags << [tag1, tag2]
+          end
+
+          it { should start_with(topic.title) }
+          it { should end_with(category.name) }
+          it { should_not include(tag1.name) }
+          it { should_not include(tag2.name) }
+        end
+      end
+    end
+  end
 end