func (statefulSetStrategy) PrepareForUpdate(ctx context.Context, obj, old runtime.Object) {
	newStatefulSet := obj.(*apps.StatefulSet)
	oldStatefulSet := old.(*apps.StatefulSet)
	// Update is not allowed to set status
	newStatefulSet.Status = oldStatefulSet.Status

	dropStatefulSetDisabledFields(newStatefulSet, oldStatefulSet)
	pod.DropDisabledTemplateFields(&newStatefulSet.Spec.Template, &oldStatefulSet.Spec.Template)

	appslisters "k8s.io/client-go/listers/apps/v1"
	core "k8s.io/client-go/testing"
	"k8s.io/client-go/tools/cache"
)

func TestStatefulSetUpdaterUpdatesSetStatus(t *testing.T) {
	set := newStatefulSet(3)
	status := apps.StatefulSetStatus{ObservedGeneration: 1, Replicas: 2}
	fakeClient := &fake.Clientset{}
	updater := NewRealStatefulSetStatusUpdater(fakeClient, nil)