@Test
    public void test_render_heading3() {
        String result = markdownRenderer.render("### Heading 3");
        assertTrue(result.contains("<h3>Heading 3</h3>"));
    }

    @Test
    public void test_render_unorderedList() {
        String markdown = "- Item 1\n- Item 2\n- Item 3";
        String result = markdownRenderer.render(markdown);
        assertTrue(result.contains("<ul>"));
        assertTrue(result.contains("<li>"));