DEV: Regression test for categories N+1 (#26204)

spec/requests/categories_controller_spec.rb

@@ -314,6 +314,31 @@ RSpec.describe CategoriesController do
       expect(category_response["subcategory_list"][0]["id"]).to eq(subcategory.id)
     end
 
+    it "doesn't do more queries when more categories exist" do
+      SiteSetting.lazy_load_categories_groups = true
+      Theme.cache.clear
+
+      Fabricate(:category, parent_category: Fabricate(:category))
+
+      before_queries =
+        track_sql_queries do
+          get "/categories.json"
+          expect(response.status).to eq(200)
+        end
+
+      Fabricate(:category, parent_category: Fabricate(:category))
+
+      Theme.cache.clear
+
+      after_queries =
+        track_sql_queries do
+          get "/categories.json"
+          expect(response.status).to eq(200)
+        end
+
+      expect(after_queries.size).to eq(before_queries.size)
+    end
+
     it "does not result in N+1 queries problem with multiple topics" do
       category1 = Fabricate(:category)
       category2 = Fabricate(:category)