assertEquals("{labels.excludedDocPaths}", FessLabels.LABELS_EXCLUDED_DOC_PATHS);
        assertEquals("{labels.excludedDocUrls}", FessLabels.LABELS_EXCLUDED_DOC_URLS);
        assertEquals("{labels.hostname}", FessLabels.LABELS_HOSTNAME);
        assertEquals("{labels.id}", FessLabels.LABELS_ID);
        assertEquals("{labels.includedPaths}", FessLabels.LABELS_INCLUDED_PATHS);

        } catch (IllegalArgumentException e) {
            // Expected
        }
    }

    // Test inheritance
    public void test_inheritance() {
        assertTrue(messages instanceof FessLabels);
        assertTrue(messages instanceof org.lastaflute.core.message.UserMessages);
    }

    // Test method chaining
    public void test_methodChaining() {
        String property1 = "prop1";