fix(redirects): handle non-verbatim targets (#9089)

* add tests

* implement fix

* add changeset

* `for const in` -> `for const of`

* reskip: external redirects are still not ignored

.changeset/silly-cycles-clap.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes an issue where redirects did not replace slugs when the target of the redirect rule was not a verbatim route in the project.

packages/astro/src/core/redirects/helpers.ts

@@ -20,7 +20,14 @@ export function redirectRouteGenerate(redirectRoute: RouteData, data: Params): s
 	if (typeof routeData !== 'undefined') {
 		return routeData?.generate(data) || routeData?.pathname || '/';
 	} else if (typeof route === 'string') {
-		return route;
+		// TODO: this logic is duplicated between here and manifest/create.ts
+		let target = route
+		for (const param of Object.keys(data)) {
+			const paramValue = data[param]!
+			target = target.replace(`[${param}]`, paramValue)
+			target = target.replace(`[...${param}]`, paramValue)
+		}
+		return target
 	} else if (typeof route === 'undefined') {
 		return '/';
 	}

packages/astro/test/redirects.test.js

@@ -15,6 +15,13 @@ describe('Astro.redirect', () => {
 				redirects: {
 					'/api/redirect': '/test',
 					'/external/redirect': 'https://example.com/',
+					// for example, the real file handling the target path may be called
+					// src/pages/not-verbatim/target1/[something-other-than-dynamic].astro
+					'/source/[dynamic]': '/not-verbatim/target1/[dynamic]',
+					// may be called src/pages/not-verbatim/target2/[abc]/[xyz].astro
+					'/source/[dynamic]/[route]': '/not-verbatim/target2/[dynamic]/[route]',
+					// may be called src/pages/not-verbatim/target3/[...rest].astro
+					'/source/[...spread]': '/not-verbatim/target3/[...spread]',
 				},
 			});
 			await fixture.build();
@@ -68,6 +75,27 @@ describe('Astro.redirect', () => {
 				const response = await app.render(request);
 				expect(response.status).to.equal(308);
 			});
+
+			it('Forwards params to the target path - single param', async () => {
+				const app = await fixture.loadTestAdapterApp();
+				const request = new Request('http://example.com/source/x');
+				const response = await app.render(request);
+				expect(response.headers.get("Location")).to.equal("/not-verbatim/target1/x");
+			});
+
+			it('Forwards params to the target path - multiple params', async () => {
+				const app = await fixture.loadTestAdapterApp();
+				const request = new Request('http://example.com/source/x/y');
+				const response = await app.render(request);
+				expect(response.headers.get("Location")).to.equal("/not-verbatim/target2/x/y");
+			});
+
+			it('Forwards params to the target path - spread param', async () => {
+				const app = await fixture.loadTestAdapterApp();
+				const request = new Request('http://example.com/source/x/y/z');
+				const response = await app.render(request);
+				expect(response.headers.get("Location")).to.equal("/not-verbatim/target3/x/y/z");
+			});
 		});
 	});