feat: add multiple set-cookie headers in middleware (#1970)

* feat: add multiple set-cookie headers in middleware

* chore: format

* chore: change string order

* chore: version

Author: sarahetter

package-lock.json

@@ -31,12 +31,11 @@ export const addMiddlewareHeaders = async (
   // We need to await the response to get the origin headers, then we can add the ones from middleware.
   const res = await originResponse
   const response = new Response(res.body, res)
-  const originCookies = response.headers.get('set-cookie')
   middlewareResponse.headers.forEach((value, key) => {
-    response.headers.set(key, value)
-    // Append origin cookies after middleware cookies
-    if (key === 'set-cookie' && originCookies) {
-      response.headers.append(key, originCookies)
+    if (key === 'set-cookie') {
+      response.headers.append(key, value)
+    } else {
+      response.headers.set(key, value)
     }
   })
   return response

packages/runtime/src/templates/edge-shared/utils.ts

@@ -52,14 +52,14 @@ describe('skip-trailing-slash-redirect', () => {
       redirect: 'manual',
     })
     expect(res.status).toBe(200)
-    expect(res.headers.get('set-cookie')).toEqual('from-middleware=1; Path=/, hello=From API')
+    expect(res.headers.get('set-cookie')).toEqual('hello=From API, from-middleware=1; Path=/')
   })
   it('should merge cookies from middleware and edge API routes correctly', async () => {
     const res = await fetchViaHTTP(next.url, '/api/test-cookie-edge', undefined, {
       redirect: 'manual',
     })
     expect(res.status).toBe(200)
-    expect(res.headers.get('set-cookie')).toEqual('from-middleware=1; Path=/, hello=From%20API; Path=/')
+    expect(res.headers.get('set-cookie')).toEqual('hello=From%20API; Path=/, from-middleware=1; Path=/')
   })
 
   if ((global as any).isNextStart) {