fix: 404 status in dev (#12980)

.changeset/itchy-trains-allow.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes a case where setting the status of a page to `404` in development would show the default 404 page (or custom one if provided) instead of using the current page

packages/astro/src/vite-plugin-astro-server/route.ts

@@ -241,7 +241,13 @@ export async function handleRoute({
 		);
 	}
 
-	if (statusCode === 404 && response.headers.get(REROUTE_DIRECTIVE_HEADER) !== 'no') {
+	if (
+		statusCode === 404 &&
+		// If the body isn't null, that means the user sets the 404 status
+		// but uses the current route to handle the 404
+		response.body === null &&
+		response.headers.get(REROUTE_DIRECTIVE_HEADER) !== 'no'
+	) {
 		const fourOhFourRoute = await matchRoute('/404', manifestData, pipeline);
 		if (fourOhFourRoute) {
 			renderContext = await RenderContext.create({

packages/astro/test/astro-response.test.js

@@ -1,9 +1,11 @@
+// @ts-check
 import assert from 'node:assert/strict';
 import { after, before, describe, it } from 'node:test';
 import { loadFixture } from './test-utils.js';
 
 // Asset bundling
 describe('Returning responses', () => {
+	/** @type {Awaited<ReturnType<typeof loadFixture>>} */
 	let fixture;
 	/** @type {import('./test-utils').DevServer} */
 	let devServer;
@@ -21,7 +23,23 @@ describe('Returning responses', () => {
 	});
 
 	it('Works from a page', async () => {
-		let response = await fixture.fetch('/not-found');
+		const response = await fixture.fetch('/not-found');
 		assert.equal(response.status, 404);
 	});
+
+	it('Returns the default 404 is body is null', async () => {
+		const response = await fixture.fetch('/not-found');
+		const html = await response.text();
+
+		assert.equal(response.status, 404);
+		assert.equal(html.includes('<pre>Path: /not-found</pre>'), true);
+	});
+
+	it('Returns the page is body is not null', async () => {
+		const response = await fixture.fetch('/not-found-custom');
+		const html = await response.text();
+
+		assert.equal(response.status, 404);
+		assert.equal(html.includes('Custom 404'), true);
+	});
 });

packages/astro/test/fixtures/astro-response/src/pages/not-found-custom.astro

@@ -0,0 +1,4 @@
+---
+Astro.response.status = 404
+---
+<div>Custom 404</div>

packages/astro/test/test-utils.js

@@ -34,12 +34,12 @@ process.env.ASTRO_TELEMETRY_DISABLED = true;
  * @property {typeof build} build
  * @property {(url: string) => string} resolveUrl
  * @property {(path: string) => Promise<boolean>} pathExists
- * @property {(url: string, opts: Parameters<typeof fetch>[1]) => Promise<Response>} fetch
+ * @property {(url: string, opts?: Parameters<typeof fetch>[1]) => Promise<Response>} fetch
  * @property {(path: string) => Promise<string>} readFile
  * @property {(path: string, updater: (content: string) => string) => Promise<void>} editFile
  * @property {(path: string) => Promise<string[]>} readdir
  * @property {(pattern: string) => Promise<string[]>} glob
- * @property {typeof dev} startDevServer
+ * @property {(inlineConfig?: Parameters<typeof dev>[0]) => ReturnType<typeof dev>} startDevServer
  * @property {typeof preview} preview
  * @property {() => Promise<void>} clean
  * @property {() => Promise<App>} loadTestAdapterApp