docList.addProcessingTime(100);
        docList.addProcessingTime(0);
        assertEquals(100, docList.getProcessingTime());
    }

    @Test
    public void test_list_operations_with_metrics() {
        DocList docList = new DocList();

        Map<String, Object> doc1 = new HashMap<>();
        doc1.put("id", "1");
        doc1.put("title", "Test Document 1");