Refactor cookie handling in CookiesMiddleware and add test case for o…

…ff-domain jar storage

scrapy/downloadermiddlewares/cookies.py

@@ -40,13 +40,11 @@ def _process_cookies(self, cookies, *, jar, request):
                 cookie_domain = cookie_domain[1:]
 
             request_domain = urlparse_cached(request).hostname.lower()
-
-            if cookie_domain and _is_public_domain(cookie_domain):
+            if _is_public_domain(cookie_domain):
                 if cookie_domain != request_domain:
                     continue
-                cookie.domain = request_domain
 
-            jar.set_cookie_if_ok(cookie, request)
+            jar.set_cookie(cookie)
 
     def process_request(self, request, spider):
         if request.meta.get("dont_merge_cookies", False):

tests/test_downloadermiddleware_cookies.py

@@ -732,3 +732,21 @@ def test_server_set_cookie_domain_public_period(self):
             "co.uk",
             cookies=True,
         )
+
+    def test_off_domain_jar_storage(self):
+        request1 = Request(
+            "https://a.example",
+            cookies=[
+                {
+                    "name": "foo",
+                    "value": "bar",
+                    "domain": "b.example",
+                },
+            ],
+        )
+        assert self.mw.process_request(request1, self.spider) is None
+        self.assertNotIn(b"Cookie", request1.headers)
+
+        request2 = Request("https://b.example/")
+        assert self.mw.process_request(request2, self.spider) is None
+        self.assertEqual(request2.headers.get(b"Cookie"), b"foo=bar")