make more specs work

app/models/list.rb

@@ -118,7 +118,7 @@ class List
   def self.get_suppliers_users_count(lists, supplier_id: nil)
     unique_supplier_user_ids = Set.new
     lists.each do |list|
-      list.user_ids.each do |uid|
+      Array.wrap(list.user_ids).each do |uid|
         unique_supplier_user_ids << [list.supplier_id, uid]
       end
     end
@@ -140,7 +140,7 @@ class List
   def self.enrich_users_number_of_lists_at_supplier(supplier_id, lists)
     counts = get_suppliers_users_count(lists, supplier_id: supplier_id)
     lists.each do |list|
-      list.users.each do |user|
+      Array.wrap(list.users).each do |user|
         user.number_of_lists_at_supplier = counts[user.id] || 1
       end
     end