fix(sitemap): url when rest parameter is used in page file names (#9975)

* fix(sitemap): url when rest parameter is used in page file names

* Update .changeset/sour-ties-sparkle.md

Co-authored-by: Florian Lefebvre <contact@florian-lefebvre.dev>

* Apply suggestions from code review

---------

Co-authored-by: Florian Lefebvre <contact@florian-lefebvre.dev>
Co-authored-by: Emanuele Stoppa <my.burning@gmail.com>

7 files changed, 77 insertions, 0 deletions

diff --git a/.changeset/sour-ties-sparkle.md b/.changeset/sour-ties-sparkle.md
new file mode 100644
index 000000000..17088feae
--- /dev/null
+++ b/.changeset/sour-ties-sparkle.md
@@ -0,0 +1,5 @@
+---
+"@astrojs/sitemap": patch
+---
+
+Fixes URL generation for routes that rest parameters and start with `/`
diff --git a/packages/integrations/sitemap/src/index.ts b/packages/integrations/sitemap/src/index.ts
index 4c049df91..4d280112b 100644
--- a/packages/integrations/sitemap/src/index.ts
+++ b/packages/integrations/sitemap/src/index.ts
@@ -98,6 +98,8 @@ const createPlugin = (options?: SitemapOptions): AstroIntegration => {
 						.map((p) => {
 							if (p.pathname !== '' && !finalSiteUrl.pathname.endsWith('/'))
 								finalSiteUrl.pathname += '/';
+							if (p.pathname.startsWith('/'))
+								p.pathname = p.pathname.slice(1);
 							const fullPath = finalSiteUrl.pathname + p.pathname;
 							return new URL(fullPath, finalSiteUrl).href;
 						});
diff --git a/packages/integrations/sitemap/test/dynamic-path.test.js b/packages/integrations/sitemap/test/dynamic-path.test.js
new file mode 100644
index 000000000..4f84af39e
--- /dev/null
+++ b/packages/integrations/sitemap/test/dynamic-path.test.js
@@ -0,0 +1,24 @@
+import {before, describe, it} from "node:test";
+import {loadFixture, readXML} from "./test-utils.js";
+import assert from "node:assert/strict";
+
+describe('Dynamic with rest parameter', () => {
+	/** @type {import('./test-utils.js').Fixture} */
+	let fixture;
+	
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/dynamic',
+		});
+		await fixture.build();
+	});
+	
+	it('Should generate correct urls', async () => {
+		const data = await readXML(fixture.readFile('/sitemap-0.xml'));
+		const urls = data.urlset.url.map((url) => url.loc[0]);
+		
+		assert.ok(urls.includes('http://example.com/'));
+		assert.ok(urls.includes('http://example.com/blog/'));
+		assert.ok(urls.includes('http://example.com/test/'));
+	});
+})
diff --git a/packages/integrations/sitemap/test/fixtures/dynamic/astro.config.mjs b/packages/integrations/sitemap/test/fixtures/dynamic/astro.config.mjs
new file mode 100644
index 000000000..7d02e26ca
--- /dev/null
+++ b/packages/integrations/sitemap/test/fixtures/dynamic/astro.config.mjs
@@ -0,0 +1,7 @@
+import { defineConfig } from 'astro/config';
+import sitemap from '@astrojs/sitemap';
+
+export default defineConfig({
+  integrations: [sitemap()],
+	site: 'http://example.com'
+})
diff --git a/packages/integrations/sitemap/test/fixtures/dynamic/package.json b/packages/integrations/sitemap/test/fixtures/dynamic/package.json
new file mode 100644
index 000000000..1eac19a1b
--- /dev/null
+++ b/packages/integrations/sitemap/test/fixtures/dynamic/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "@test/sitemap-dynamic",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*",
+    "@astrojs/sitemap": "workspace:*"
+  }
+}
diff --git a/packages/integrations/sitemap/test/fixtures/dynamic/src/pages/[...slug].astro b/packages/integrations/sitemap/test/fixtures/dynamic/src/pages/[...slug].astro
new file mode 100644
index 000000000..9622cb374
--- /dev/null
+++ b/packages/integrations/sitemap/test/fixtures/dynamic/src/pages/[...slug].astro
@@ -0,0 +1,21 @@
+---
+export async function getStaticPaths() {
+	return [
+		{
+			params: {
+				slug: undefined,
+			}
+		},
+		{
+			params: {
+				slug: '/blog'
+			}
+		},
+		{
+			params: {
+				slug: '/test'
+			}
+		}
+	];
+}
+---
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 9ff7f3fa7..a6e62986d 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -4577,6 +4577,15 @@ importers:
         specifier: 0.6.2
         version: 0.6.2
 
+  packages/integrations/sitemap/test/fixtures/dynamic:
+    dependencies:
+      '@astrojs/sitemap':
+        specifier: workspace:*
+        version: link:../../..
+      astro:
+        specifier: workspace:*
+        version: link:../../../../../astro
+
   packages/integrations/sitemap/test/fixtures/ssr:
     dependencies:
       '@astrojs/sitemap':