1 files changed, 63 insertions, 0 deletions
diff --git a/spec/models/preloaders/group_root_ancestor_preloader_spec.rb b/spec/models/preloaders/group_root_ancestor_preloader_spec.rb
new file mode 100644
index 00000000000..0d622e84ef1
--- /dev/null
+++ b/spec/models/preloaders/group_root_ancestor_preloader_spec.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Preloaders::GroupRootAncestorPreloader do
+  let_it_be(:user) { create(:user) }
+  let_it_be(:root_parent1) { create(:group, :private, name: 'root-1', path: 'root-1') }
+  let_it_be(:root_parent2) { create(:group, :private, name: 'root-2', path: 'root-2') }
+  let_it_be(:guest_group) { create(:group, name: 'public guest', path: 'public-guest') }
+  let_it_be(:private_maintainer_group) { create(:group, :private, name: 'b private maintainer', path: 'b-private-maintainer', parent: root_parent1) }
+  let_it_be(:private_developer_group) { create(:group, :private, project_creation_level: nil, name: 'c public developer', path: 'c-public-developer') }
+  let_it_be(:public_maintainer_group) { create(:group, :private, name: 'a public maintainer', path: 'a-public-maintainer', parent: root_parent2) }
+
+  let(:root_query_regex) { /\ASELECT.+FROM "namespaces" WHERE "namespaces"."id" = \d+/ }
+  let(:additional_preloads) { [] }
+  let(:groups) { [guest_group, private_maintainer_group, private_developer_group, public_maintainer_group] }
+  let(:pristine_groups) { Group.where(id: groups) }
+
+  shared_examples 'executes N matching DB queries' do |expected_query_count, query_method = nil|
+    it 'executes the specified root_ancestor queries' do
+      expect do
+        pristine_groups.each do |group|
+          root_ancestor = group.root_ancestor
+
+          root_ancestor.public_send(query_method) if query_method.present?
+        end
+      end.to make_queries_matching(root_query_regex, expected_query_count)
+    end
+
+    it 'strong_memoizes the correct root_ancestor' do
+      pristine_groups.each do |group|
+        expected_parent_id = group.root_ancestor.id == group.id ? nil : group.root_ancestor.id
+
+        expect(group.parent_id).to eq(expected_parent_id)
+      end
+    end
+  end
+
+  context 'when the preloader is used' do
+    before do
+      preload_ancestors
+    end
+
+    context 'when no additional preloads are provided' do
+      it_behaves_like 'executes N matching DB queries', 0
+    end
+
+    context 'when additional preloads are provided' do
+      let(:additional_preloads) { [:route] }
+      let(:root_query_regex) { /\ASELECT.+FROM "routes" WHERE "routes"."source_id" = \d+/ }
+
+      it_behaves_like 'executes N matching DB queries', 0, :full_path
+    end
+  end
+
+  context 'when the preloader is not used' do
+    it_behaves_like 'executes N matching DB queries', 2
+  end
+
+  def preload_ancestors
+    described_class.new(pristine_groups, additional_preloads).execute
+  end
+end