System.clearProperty(Constants.FESS_CONFIG_PREFIX + testKey);
        }
    }

    // Test caching mechanism
    public void test_get_caching() {
        // Get property twice to test caching behavior
        String testKey = "domain.title";
        String value1 = fessConfig.get(testKey);
        String value2 = fessConfig.get(testKey);

        // Values should be the same

    public void test_append_nullValue() {
        StringBuilder buf = new StringBuilder();
        Supplier<Object> supplier = () -> null;

        monitorTarget.append(buf, "testKey", supplier);
        assertEquals("\"testKey\":null", buf.toString());
    }

    // Test append method with Integer value
    public void test_append_integerValue() {
        StringBuilder buf = new StringBuilder();

        }
    }

    // Test sendMail method
    public void test_sendMail_withNotificationDisabled() {
        Map<String, String> infoMap = new HashMap<>();
        infoMap.put("TestKey", "TestValue");

        // Should not throw exception when notification is disabled
        try {
            crawler.sendMail(infoMap);
        } catch (Exception e) {