Merge branch '31851-set-inverse_of-on-clusters-applications-association' into 'master'

Resolve "Set `inverse_of` on Clusters <-> Applications association"

See merge request gitlab-org/gitlab!17285

app/models/clusters/cluster.rb

@@ -39,7 +39,7 @@ module Clusters
 
     def self.has_one_cluster_application(name) # rubocop:disable Naming/PredicateName
       application = APPLICATIONS[name.to_s]
-      has_one application.association_name, class_name: application.to_s # rubocop:disable Rails/ReflectionClassName
+      has_one application.association_name, class_name: application.to_s, inverse_of: :cluster # rubocop:disable Rails/ReflectionClassName
     end
 
     has_one_cluster_application :helm

spec/models/clusters/cluster_spec.rb

@@ -38,6 +38,15 @@ describe Clusters::Cluster, :use_clean_rails_memory_store_caching do
 
   it { is_expected.to respond_to :project }
 
+  describe 'applications have inverse_of: :cluster option' do
+    let(:cluster) { create(:cluster) }
+    let!(:helm) { create(:clusters_applications_helm, cluster: cluster) }
+
+    it 'does not do a third query when referencing cluster again' do
+      expect { cluster.application_helm.cluster }.not_to exceed_query_limit(2)
+    end
+  end
+
   describe '.enabled' do
     subject { described_class.enabled }