wp-now: add /wp-admin redirection with trailing slash (#60)

Add a middleware to redirect to `/wp-admin` to add the trailing slash `/wp-admin/`. Fixes core sidebar links.

packages/wp-now/src/add-trailing-slash.ts

@@ -0,0 +1,17 @@
+/**
+ * Adds redirection adding a trailing slash, when a request matches a given path.
+ * @param path - The path to add a trailing slash to. E.g. '/wp-admin'
+ * @returns  - Returns a middleware function that may redirect adding a trailing slash to the given path. E.g. '/wp-admin/'
+ */
+export function addTrailingSlash(path) {
+	return (req, res, next) => {
+		const urlParts = req.url.split('?');
+		const url = urlParts[0];
+		const queryString = req.url.substr(url.length);
+		if (url === path) {
+			res.redirect(301, `${path}/${queryString}`);
+		} else {
+			next();
+		}
+	};
+}

packages/wp-now/src/start-server.ts

@@ -7,6 +7,7 @@ import { portFinder } from './port-finder';
 import { NodePHP } from '@php-wasm/node';
 import startWPNow from './wp-now';
 import { output } from './output';
+import { addTrailingSlash } from './add-trailing-slash';
 
 function requestBodyToMultipartFormData(json, boundary) {
 	let multipartData = '';
@@ -49,6 +50,7 @@ export async function startServer(
 	}
 	const app = express();
 	app.use(fileUpload());
+	app.use(addTrailingSlash('/wp-admin'));
 	const port = await portFinder.getOpenPort();
 	const { php, options: wpNowOptions } = await startWPNow(options);
 

packages/wp-now/src/tests/add-trailing-slash.spec.ts

@@ -0,0 +1,34 @@
+import { addTrailingSlash } from '../add-trailing-slash';
+
+describe('add trailing slash middleware', () => {
+	const middlewareTrailingSlash = addTrailingSlash('/wp-admin');
+	let res, next;
+
+	beforeEach(() => {
+		res = {
+			redirect: vi.fn(),
+		};
+		next = vi.fn();
+	});
+
+	test('adds a trailing slash to the given path', () => {
+		const req = { url: '/wp-admin' };
+		middlewareTrailingSlash(req, res, next);
+		expect(res.redirect).toHaveBeenCalledWith(301, '/wp-admin/');
+		expect(next).not.toHaveBeenCalled();
+	});
+
+	test('adds a trailing slash to the given path with parameters', () => {
+		const req = { url: '/wp-admin?foo=bar' };
+		middlewareTrailingSlash(req, res, next);
+		expect(res.redirect).toHaveBeenCalledWith(301, '/wp-admin/?foo=bar');
+		expect(next).not.toHaveBeenCalled();
+	});
+
+	test('does not add a trailing slash to the given path', () => {
+		const req = { url: '/wp-admin/' };
+		middlewareTrailingSlash(req, res, next);
+		expect(res.redirect).not.toHaveBeenCalled();
+		expect(next).toHaveBeenCalled();
+	});
+});