1 files changed, 51 insertions, 0 deletions
diff --git a/spec/models/preloaders/users_max_access_level_in_projects_preloader_spec.rb b/spec/models/preloaders/users_max_access_level_in_projects_preloader_spec.rb
new file mode 100644
index 00000000000..7ecb6bb9861
--- /dev/null
+++ b/spec/models/preloaders/users_max_access_level_in_projects_preloader_spec.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+RSpec.describe Preloaders::UsersMaxAccessLevelInProjectsPreloader do
+  let_it_be(:user1) { create(:user) }
+  let_it_be(:user2) { create(:user) }
+
+  let_it_be(:project_1) { create(:project) }
+  let_it_be(:project_2) { create(:project) }
+  let_it_be(:project_3) { create(:project) }
+
+  let(:projects) { [project_1, project_2, project_3] }
+  let(:users) { [user1, user2] }
+
+  before do
+    project_1.add_developer(user1)
+    project_1.add_developer(user2)
+
+    project_2.add_developer(user1)
+    project_2.add_developer(user2)
+
+    project_3.add_developer(user1)
+    project_3.add_developer(user2)
+  end
+
+  context 'preload maximum access level to avoid querying project_authorizations', :request_store do
+    it 'avoids N+1 queries', :request_store do
+      Preloaders::UsersMaxAccessLevelInProjectsPreloader.new(projects: projects, users: users).execute
+
+      expect(count_queries).to eq(0)
+    end
+
+    it 'runs N queries without preloading' do
+      query_count_without_preload = count_queries
+
+      Preloaders::UsersMaxAccessLevelInProjectsPreloader.new(projects: projects, users: users).execute
+      count_queries_with_preload = count_queries
+
+      expect(count_queries_with_preload).to be < query_count_without_preload
+    end
+  end
+
+  def count_queries
+    ActiveRecord::QueryRecorder.new do
+      projects.each do |project|
+        user1.can?(:read_project, project)
+        user2.can?(:read_project, project)
+      end
+    end.count
+  end
+end