example.go

func verifyResourceClean(
	ctx context.Context,
	k8sClient client.Client,
	resource client.ObjectList,
	ignoredObjects ...client.ObjectKey,
) error {
	if err := k8sClient.List(ctx, resource); err != nil {
		return err
	}
	list := reflect.Indirect(reflect.ValueOf(resource))
	filtered := filterItems(list, ignoredObjects...)
	if len(filtered) > 0 {
		return fmt.Errorf("%w: found non-ignored objects on cluster: %s",
			ErrResourceNotClean, pretty.Sprint(filtered))
	}
	return nil
}

func filterItems(
	list reflect.Value,
	ignoredObjects ...client.ObjectKey,
) []interface{} {
	var filtered []interface{}
	items := list.FieldByName("Items")

	for i := 0; i < items.Len(); i++ {
		val := items.Index(i)
		name := val.FieldByName("Name").String()
		namespace := val.FieldByName("Namespace").String()
		isIgnored := func() bool {
			for _, ignoredObject := range ignoredObjects {
				if name == ignoredObject.Name && namespace == ignoredObject.Namespace {
					return true
				}
			}
			return false
		}
		if !isIgnored() {
			filtered = append(filtered, val.Interface())
		}
	}
	return filtered
}