fix: merge Middleware and API route response cookies (#1870)

* fix: appending origin cookies to prevent override and to match test order

* test: remove usuallySkip from tests related to middleware + API cookie merge

* Fix: let to const

Co-authored-by: Erica Pisani <pisani.erica@gmail.com>

* change to strict comparison

Co-authored-by: Matt Kane <matt.kane@netlify.com>

Co-authored-by: Erica Pisani <pisani.erica@gmail.com>
Co-authored-by: Matt Kane <matt.kane@netlify.com>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

Author: 4 people

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

@@ -31,8 +31,13 @@ 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)
+    }
   })
   return response
 }

test/e2e/modified-tests/skip-trailing-slash-redirect/index.test.ts

@@ -47,16 +47,14 @@ describe('skip-trailing-slash-redirect', () => {
     expect(res.headers.get('x-from-middleware')).toBe('true')
     expect(await res.text()).toBe('hello from middleware')
   })
-  // NTL Skip
-  usuallySkip('should merge cookies from middleware and API routes correctly', async () => {
+  it('should merge cookies from middleware and API routes correctly', async () => {
     const res = await fetchViaHTTP(next.url, '/api/test-cookie', undefined, {
       redirect: 'manual',
     })
     expect(res.status).toBe(200)
     expect(res.headers.get('set-cookie')).toEqual('from-middleware=1; Path=/, hello=From API')
   })
-  // NTL Skip
-  usuallySkip('should merge cookies from middleware and edge API routes correctly', async () => {
+  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',
     })