fix: parse "Set-Cookie" response header with commas correctly (#2075)

Co-authored-by: ushiboy <ushiboy.dev@gmail.com>

src/core/utils/HttpResponse/decorators.ts

@@ -1,5 +1,6 @@
 import statuses from '@bundled-es-modules/statuses'
 import type { HttpResponseInit } from '../../HttpResponse'
+import { Headers as HeadersPolyfill } from 'headers-polyfill'
 
 const { message } = statuses
 
@@ -40,10 +41,13 @@ export function decorateResponse(
   // Cookie forwarding is only relevant in the browser.
   if (typeof document !== 'undefined') {
     // Write the mocked response cookies to the document.
-    // Note that Fetch API Headers will concatenate multiple "Set-Cookie"
-    // headers into a single comma-separated string, just as it does
-    // with any other multi-value headers.
-    const responseCookies = init.headers.get('Set-Cookie')?.split(',') || []
+    // Use `headers-polyfill` to get the Set-Cookie header value correctly.
+    // This is an alternative until TypeScript 5.2
+    // and Node.js v20 become the minimum supported version
+    // and getSetCookie in Headers can be used directly.
+    const responseCookies = HeadersPolyfill.prototype.getSetCookie.call(
+      init.headers,
+    )
 
     for (const cookieString of responseCookies) {
       // No need to parse the cookie headers because it's defined

test/browser/rest-api/cookies.mocks.ts

@@ -23,6 +23,7 @@ const worker = setupWorker(
         headers: [
           ['Set-Cookie', 'firstCookie=yes'],
           ['Set-Cookie', 'secondCookie=no; Max-Age=1000'],
+          ['Set-Cookie', 'thirdCookie=1,2,3'],
         ],
       },
     )

test/browser/rest-api/cookies.test.ts

@@ -48,5 +48,6 @@ test('allows setting multiple response cookies', async ({
   expect(allCookies).toEqual({
     firstCookie: 'yes',
     secondCookie: 'no',
+    thirdCookie: '1,2,3',
   })
 })