diff --git a/__tests__/renderMarkdown.test.js b/__tests__/renderMarkdown.test.js
new file mode 100644
index 0000000..2f8d5b0
--- /dev/null
+++ b/__tests__/renderMarkdown.test.js
@@ -0,0 +1,75 @@
+jest.mock('@11ty/eleventy', () => {
+  const fs = require('fs');
+  const path = require('path');
+  return class Eleventy {
+    constructor(input, output) {
+      this.input = input;
+      this.output = output;
+    }
+    setConfig() {}
+    async write() {
+      const walk = d => {
+        const entries = fs.readdirSync(d, { withFileTypes: true });
+        let files = [];
+        for (const e of entries) {
+          const p = path.join(d, e.name);
+          if (e.isDirectory()) files = files.concat(walk(p));
+          else if (p.endsWith('.md')) files.push(p);
+        }
+        return files;
+      };
+      for (const file of walk(this.input)) {
+        const rel = path.relative(this.input, file).replace(/\.md$/, '.html');
+        const dest = path.join(this.output, rel);
+        fs.mkdirSync(path.dirname(dest), { recursive: true });
+        fs.writeFileSync(dest, '<header></header><aside class="sidebar"></aside>');
+      }
+    }
+  };
+});
+
+const fs = require('fs');
+const path = require('path');
+const os = require('os');
+const { generate } = require('../src/generator');
+
+function getPaths(tree) {
+  const paths = [];
+  for (const node of tree) {
+    if (node.path) paths.push(node.path);
+    if (node.children) paths.push(...getPaths(node.children));
+  }
+  return paths;
+}
+
+test('markdown files render with layout and appear in nav/search', async () => {
+  const tmp = fs.mkdtempSync(path.join(os.tmpdir(), 'df-test-'));
+  const contentDir = path.join(tmp, 'content');
+  const outputDir = path.join(tmp, '_site');
+  fs.mkdirSync(path.join(contentDir, 'guide'), { recursive: true });
+  fs.writeFileSync(path.join(contentDir, 'index.md'), '# Home\nWelcome');
+  fs.writeFileSync(path.join(contentDir, 'guide', 'install.md'), '# Install\nSteps');
+  const configPath = path.join(tmp, 'config.yaml');
+  fs.writeFileSync(configPath, 'site:\n  title: Test\n');
+
+  await generate({ contentDir, outputDir, configPath });
+
+  const indexHtml = fs.readFileSync(path.join(outputDir, 'index.html'), 'utf8');
+  const installHtml = fs.readFileSync(path.join(outputDir, 'guide', 'install.html'), 'utf8');
+  expect(indexHtml).toContain('<header');
+  expect(indexHtml).toContain('<aside class="sidebar"');
+  expect(installHtml).toContain('<header');
+  expect(installHtml).toContain('<aside class="sidebar"');
+
+  const nav = JSON.parse(fs.readFileSync(path.join(outputDir, 'navigation.json'), 'utf8'));
+  const navPaths = getPaths(nav);
+  expect(navPaths).toContain('/index.html');
+  expect(navPaths).toContain('/guide/install.html');
+
+  const search = JSON.parse(fs.readFileSync(path.join(outputDir, 'search-index.json'), 'utf8'));
+  const docs = search.docs.map(d => d.id);
+  expect(docs).toContain('index.html');
+  expect(docs).toContain('guide/install.html');
+
+  fs.rmSync(tmp, { recursive: true, force: true });
+});