fix: request creation when double slashes exist

@see: remix-run/remix#5336

Signed-off-by: Logan McAnsh <logan@mcan.sh>

Author: mcansh

packages/remix-fastify/__tests__/index.test.ts

@@ -66,6 +66,32 @@ describe("fastify createRequestHandler", () => {
       expect(response.body).toBe("URL: /foo/bar");
     });
 
+    it("handles root // URLs", async () => {
+      mockedCreateRequestHandler.mockImplementation(() => async (req) => {
+        return new Response("URL: " + new URL(req.url).pathname);
+      });
+
+      let app = createApp();
+
+      let response = await app.inject("//");
+
+      expect(response.statusCode).toBe(200);
+      expect(response.body).toBe("URL: //");
+    });
+
+    it("handles nested // URLs", async () => {
+      mockedCreateRequestHandler.mockImplementation(() => async (req) => {
+        return new Response("URL: " + new URL(req.url).pathname);
+      });
+
+      let app = createApp();
+
+      let response = await app.inject("//foo//bar");
+
+      expect(response.statusCode).toBe(200);
+      expect(response.body).toBe("URL: //foo//bar");
+    });
+
     it("handles null body", async () => {
       mockedCreateRequestHandler.mockImplementation(() => async () => {
         return new Response(null, { status: 200 });

packages/remix-fastify/src/server.ts

@@ -83,7 +83,7 @@ export function createRemixHeaders(
 
 export function createRemixRequest(request: FastifyRequest): NodeRequest {
   let origin = `${request.protocol}://${request.hostname}`;
-  let url = new URL(request.url, origin);
+  let url = `${origin}${request.url}`;
 
   let controller = new AbortController();
 
@@ -97,7 +97,7 @@ export function createRemixRequest(request: FastifyRequest): NodeRequest {
     init.body = request.raw;
   }
 
-  return new NodeRequest(url.href, init);
+  return new NodeRequest(url, init);
 }
 
 export async function sendRemixResponse(