fix(@astrojs/node): handler should work with express

.changeset/rich-tigers-march.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/node': patch
+---
+
+Fix an issue where `express` couldn't use the `handler` in `middleware` mode.

packages/integrations/node/package.json

@@ -50,6 +50,7 @@
     "cheerio": "1.0.0-rc.12",
     "mocha": "^9.2.2",
     "node-mocks-http": "^1.13.0",
-    "undici": "^5.22.1"
+    "undici": "^5.22.1",
+    "express": "^4.18.2"
   }
 }

packages/integrations/node/src/nodeMiddleware.ts

@@ -7,14 +7,22 @@ import type { ErrorHandlerParams, Options, RequestHandlerParams } from './types'
 
 // Disable no-unused-vars to avoid breaking signature change
 // eslint-disable-next-line @typescript-eslint/no-unused-vars
-export default function (app: NodeApp, _mode: Options['mode']) {
+export default function (app: NodeApp, mode: Options['mode']) {
 	return async function (...args: RequestHandlerParams | ErrorHandlerParams) {
 		let error = null;
-		let [req, res, next, locals] = args as RequestHandlerParams;
+		let locals;
+		let [req, res, next] = args as RequestHandlerParams;
+		if (mode === 'middleware') {
+			let { [3]: _locals } = args;
+			locals = _locals;
+		}
 
 		if (args[0] instanceof Error) {
-			[error, req, res, next, locals] = args as ErrorHandlerParams;
-
+			[error, req, res, next] = args as ErrorHandlerParams;
+			if (mode === 'middleware') {
+				let { [4]: _locals } = args as ErrorHandlerParams;
+				locals = _locals;
+			}
 			if (error) {
 				if (next) {
 					return next(error);

packages/integrations/node/test/fixtures/node-middleware/src/pages/ssr.ts

@@ -0,0 +1,9 @@
+export async function get() {
+	let number = Math.random();
+	return {
+		body: JSON.stringify({
+			number,
+			message: `Here's a random number: ${number}`,
+		}),
+	};
+}

packages/integrations/node/test/node-middleware.test.js

@@ -2,6 +2,7 @@ import nodejs from '../dist/index.js';
 import { loadFixture } from './test-utils.js';
 import { expect } from 'chai';
 import * as cheerio from 'cheerio';
+import express from 'express';
 
 /**
  * @typedef {import('../../../astro/test/test-utils').Fixture} Fixture
@@ -14,7 +15,7 @@ async function load() {
 	return mod;
 }
 
-describe('behavior from middleware', () => {
+describe('behavior from middleware, standalone', () => {
 	/** @type {import('./test-utils').Fixture} */
 	let fixture;
 	let server;
@@ -34,7 +35,7 @@ describe('behavior from middleware', () => {
 	});
 
 	after(async () => {
-		await server.stop();
+		await server.close();
 		await fixture.clean();
 		delete process.env.PRERENDER;
 	});
@@ -53,3 +54,42 @@ describe('behavior from middleware', () => {
 		});
 	});
 });
+
+describe('behavior from middleware, middleware', () => {
+	/** @type {import('./test-utils').Fixture} */
+	let fixture;
+	let server;
+
+	before(async () => {
+		process.env.ASTRO_NODE_AUTOSTART = 'disabled';
+		process.env.PRERENDER = false;
+		fixture = await loadFixture({
+			root: './fixtures/node-middleware/',
+			output: 'server',
+			adapter: nodejs({ mode: 'middleware' }),
+		});
+		await fixture.build();
+		const { handler } = await load();
+		const app = express();
+		app.use(handler);
+		server = app.listen(4321);
+	});
+
+	after(async () => {
+		await server.close();
+		await fixture.clean();
+		delete process.env.PRERENDER;
+	});
+
+	it('when mode is standalone', async () => {
+		const res = await fetch(`http://localhost:4321/ssr`);
+
+		expect(res.status).to.equal(200);
+
+		const html = await res.text();
+		const $ = cheerio.load(html);
+
+		const body = $('body');
+		expect(body.text()).to.contain("Here's a random number");
+	});
+});