}
    }

    // Test edge cases to understand the validation behavior
    public void test_edgeCaseBehavior() {
        String[] edgeCases = { "0 0 25 * * ?", // Invalid day of month
                "0 60 * * * ?", // Invalid minute
                "0 0 0 32 1 ?", // Invalid day
                "0 0 0 1 13 ?", // Invalid month
        };

        assertFalse(thumbnailGenerator.generate("", tempOutputFile));
    }

    public void test_generate_withNullOutputFile() {
        // Test generation with null output file
        String thumbnailId = "test-thumbnail-002";
        assertFalse(thumbnailGenerator.generate(thumbnailId, null));
    }

    public void test_generate_withInvalidOutputPath() throws IOException {
        // Test generation with non-writable output file

                "config_id", "W01", //
                "url", "http://test.com/001"//
        )));
        docList.add(new HashMap<>(Map.of(//
                "_id", "002", //
                "thumbnail", "http://test.com/002", //
                "url", "http://test.com/002"//
        )));
        indexingHelper.sendDocuments(client, docList);
        assertEquals(0, docList.size());
        assertEquals(2, sentDocList.size());