if err := DB.Model(&user2).Association("Pets").Append(&pets2); err != nil {
		t.Fatalf("Error happened when append pet, got %v", err)
	}

	for _, pet := range pets2 {
		pet := pet
		if pet.ID == 0 {
			t.Fatalf("Pet's ID should be created")
		}

		user.Pets = append(user.Pets, &pet)
	}

	CheckUser(t, user2, user)