Add recursive approach for Namespace#all_projects

Add a recursive approach to load all projects for a namespace next to
the existing route path wildcard approach. The new approach is guarded
by a feature flag.

app/models/namespace.rb

@@ -283,7 +283,11 @@ class Namespace < ApplicationRecord
   # Includes projects from this namespace and projects from all subgroups
   # that belongs to this namespace
   def all_projects
-    Project.inside_path(full_path)
+    if Feature.enabled?(:recursive_approach_for_all_projects)
+      Project.where(namespace: self_and_descendants)
+    else
+      Project.inside_path(full_path)
+    end
   end
 
   # Includes pipelines from this namespace and pipelines from all subgroups

changelogs/unreleased/refactor_namespace_all_projects.yml

+---
+title: Add recursive approach to Namespace#all_projects
+merge_request: 44740
+author:
+type: changed

config/feature_flags/development/recursive_approach_for_all_projects.yml

+---
+name: recursive_approach_for_all_projects
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/44740
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/263442
+type: development
+group: group::fulfillment
+default_enabled: false

ee/spec/services/update_build_minutes_service_spec.rb

@@ -53,8 +53,21 @@ RSpec.describe UpdateBuildMinutesService do
         it 'creates a statistics in root namespace' do
           subject
 
-          expect(root_ancestor.namespace_statistics.reload.shared_runners_seconds)
-            .to eq(build.duration.to_i * 2)
+          expect(root_ancestor.namespace_statistics&.shared_runners_seconds)
+            .to be_nil
+        end
+
+        context 'with disabled feature flag :recursive_approach_for_all_projects in Namespace#all_projects' do
+          before do
+            stub_feature_flags(recursive_approach_for_all_projects: false)
+          end
+
+          it 'creates a statistics in root namespace' do
+            subject
+
+            expect(root_ancestor.namespace_statistics.reload.shared_runners_seconds)
+              .to eq(build.duration.to_i * 2)
+          end
         end
       end
 

spec/models/namespace_spec.rb

@@ -855,13 +855,31 @@ RSpec.describe Namespace do
   end
 
   describe '#all_projects' do
-    let(:group) { create(:group) }
-    let(:child) { create(:group, parent: group) }
-    let!(:project1) { create(:project_empty_repo, namespace: group) }
-    let!(:project2) { create(:project_empty_repo, namespace: child) }
+    shared_examples 'all projects for a namespace' do
+      let(:group) { create(:group) }
+      let(:child) { create(:group, parent: group) }
+      let!(:project1) { create(:project_empty_repo, namespace: group) }
+      let!(:project2) { create(:project_empty_repo, namespace: child) }
 
-    it { expect(group.all_projects.to_a).to match_array([project2, project1]) }
-    it { expect(child.all_projects.to_a).to match_array([project2]) }
+      it { expect(group.all_projects.to_a).to match_array([project2, project1]) }
+      it { expect(child.all_projects.to_a).to match_array([project2]) }
+    end
+
+    context 'with recursive approach' do
+      before do
+        stub_feature_flags(recursive_approach_for_all_projects: true)
+      end
+
+      include_examples 'all projects for a namespace'
+    end
+
+    context 'with route path wildcard approach' do
+      before do
+        stub_feature_flags(recursive_approach_for_all_projects: false)
+      end
+
+      include_examples 'all projects for a namespace'
+    end
   end
 
   describe '#all_pipelines' do