1 files changed, 55 insertions, 0 deletions
diff --git a/spec/models/preloaders/project_policy_preloader_spec.rb b/spec/models/preloaders/project_policy_preloader_spec.rb
new file mode 100644
index 00000000000..79f232f5ce2
--- /dev/null
+++ b/spec/models/preloaders/project_policy_preloader_spec.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Preloaders::ProjectPolicyPreloader do
+  let_it_be(:user) { create(:user) }
+  let_it_be(:root_parent) { create(:group, :private, name: 'root-1', path: 'root-1') }
+  let_it_be(:guest_project) { create(:project, name: 'public guest', path: 'public-guest') }
+  let_it_be(:private_maintainer_project) do
+    create(:project, :private, name: 'b private maintainer', path: 'b-private-maintainer', namespace: root_parent)
+  end
+
+  let_it_be(:private_developer_project) do
+    create(:project, :private, name: 'c public developer', path: 'c-public-developer')
+  end
+
+  let_it_be(:public_maintainer_project) do
+    create(:project, :private, name: 'a public maintainer', path: 'a-public-maintainer')
+  end
+
+  let(:base_projects) do
+    Project.where(id: [guest_project, private_maintainer_project, private_developer_project, public_maintainer_project])
+  end
+
+  before_all do
+    guest_project.add_guest(user)
+    private_maintainer_project.add_maintainer(user)
+    private_developer_project.add_developer(user)
+    public_maintainer_project.add_maintainer(user)
+  end
+
+  it 'avoids N+1 queries when authorizing a list of projects', :request_store do
+    preload_projects_for_policy(user)
+    control = ActiveRecord::QueryRecorder.new { authorize_all_projects(user) }
+
+    new_project1 = create(:project, :private).tap { |project| project.add_maintainer(user) }
+    new_project2 = create(:project, :private, namespace: root_parent)
+
+    another_root = create(:group, :private, name: 'root-3', path: 'root-3')
+    new_project3 = create(:project, :private, namespace: another_root).tap { |project| project.add_maintainer(user) }
+
+    pristine_projects = Project.where(id: base_projects + [new_project1, new_project2, new_project3])
+
+    preload_projects_for_policy(user, pristine_projects)
+    expect { authorize_all_projects(user, pristine_projects) }.not_to exceed_query_limit(control)
+  end
+
+  def authorize_all_projects(current_user, project_list = base_projects)
+    project_list.each { |project| current_user.can?(:read_project, project) }
+  end
+
+  def preload_projects_for_policy(current_user, project_list = base_projects)
+    described_class.new(project_list, current_user).execute
+  end
+end