public void test_isAvailable() {
        // Test default implementation
        generator = new TestThumbnailGenerator();
        assertTrue(generator.isAvailable());
    }

    @Test
    public void test_isTarget() {
        // Test isTarget method
        generator = new TestThumbnailGenerator();
        Map<String, Object> docMap = new HashMap<>();

        // Note: isTarget requires FessConfig which needs container