Tuple3<String, String, String> task = thumbnailGenerator.createTask(path, docMap);
        assertNull(task);
    }

    public void test_multipleGenerations() {
        // Test multiple thumbnail generations
        for (int i = 0; i < 5; i++) {
            String thumbnailId = "test-thumbnail-" + i;
            File outputFile = new File(tempDir.toFile(), "thumbnail-" + i + ".png");