// test delete
	if err := tx.Model(&item).Association("Contents").Unscoped().Delete(&contents[0]); err != nil {
		t.Errorf("failed to delete Contents, got error: %v", err)
	}
	if count := tx.Model(&item).Association("Contents").Count(); count != 2 {
		t.Errorf("expected %d contents, got %d", 2, count)
	}

	// test clear
	if err := tx.Model(&item).Association("Contents").Unscoped().Clear(); err != nil {