2 files changed, 45 insertions, 6 deletions
diff --git a/packages/integrations/mdx/test/fixtures/mdx-optimize/astro.config.mjs b/packages/integrations/mdx/test/fixtures/mdx-optimize/astro.config.mjs
index 204549479..a3626c3a3 100644
--- a/packages/integrations/mdx/test/fixtures/mdx-optimize/astro.config.mjs
+++ b/packages/integrations/mdx/test/fixtures/mdx-optimize/astro.config.mjs
@@ -1,9 +1,37 @@
 import mdx from '@astrojs/mdx';
 
 export default {
-	integrations: [mdx({
-		optimize: {
-			ignoreElementNames: ['strong']
-		}
-	})]
-}
+	integrations: [
+		mdx({
+			optimize: {
+				ignoreElementNames: ['strong'],
+			},
+		}),
+	],
+	markdown: {
+		rehypePlugins: [
+			() => {
+				return (tree) => {
+					tree.children.push({
+						type: 'root',
+						children: [
+							{
+								type: 'element',
+								tagName: 'p',
+								properties: {
+									id: 'injected-root-hast',
+								},
+								children: [
+									{
+										type: 'text',
+										value: 'Injected root hast from rehype plugin',
+									},
+								],
+							},
+						],
+					});
+				};
+			},
+		],
+	},
+};
diff --git a/packages/integrations/mdx/test/mdx-optimize.test.js b/packages/integrations/mdx/test/mdx-optimize.test.js
index 47acfdff8..c45ecda15 100644
--- a/packages/integrations/mdx/test/mdx-optimize.test.js
+++ b/packages/integrations/mdx/test/mdx-optimize.test.js
@@ -47,4 +47,15 @@ describe('MDX optimize', () => {
 		assert.notEqual(blockquote, null);
 		assert.equal(blockquote.textContent.includes('I like pancakes'), true);
 	});
+
+	it('renders MDX with rehype plugin that incorrectly injects root hast node', async () => {
+		const html = await fixture.readFile('/import/index.html');
+		const { document } = parseHTML(html);
+
+		assert.doesNotMatch(html, /set:html=/);
+		assert.equal(
+			document.getElementById('injected-root-hast').textContent,
+			'Injected root hast from rehype plugin',
+		);
+	});
 });