realm: Allow setting notification settings to unsubscribed private streams.

We previously did not allow setting signup_notifications_stream and
notifications_stream settings to private streams that admin is not
subscribed to, even when admins have access to metadata of all the
streams in the realm and can see them in the dropdown options as well.

This commit fixes it to allow admins to set these settings to private
streams that the admin is not subscribed to.

zerver/tests/test_realm.py

@@ -494,6 +494,15 @@ class RealmTest(ZulipTestCase):
         assert realm.notifications_stream is not None
         self.assertEqual(realm.notifications_stream.id, new_notif_stream_id)
 
+        # Test that admin can set the setting to an unsubscribed private stream as well.
+        new_notif_stream_id = self.make_stream("private_stream", invite_only=True).id
+        req = dict(notifications_stream_id=orjson.dumps(new_notif_stream_id).decode())
+        result = self.client_patch("/json/realm", req)
+        self.assert_json_success(result)
+        realm = get_realm("zulip")
+        assert realm.notifications_stream is not None
+        self.assertEqual(realm.notifications_stream.id, new_notif_stream_id)
+
         invalid_notif_stream_id = 1234
         req = dict(notifications_stream_id=orjson.dumps(invalid_notif_stream_id).decode())
         result = self.client_patch("/json/realm", req)
@@ -563,6 +572,18 @@ class RealmTest(ZulipTestCase):
         assert realm.signup_notifications_stream is not None
         self.assertEqual(realm.signup_notifications_stream.id, new_signup_notifications_stream_id)
 
+        # Test that admin can set the setting to an unsubscribed private stream as well.
+        new_signup_notifications_stream_id = self.make_stream("private_stream", invite_only=True).id
+        req = dict(
+            signup_notifications_stream_id=orjson.dumps(new_signup_notifications_stream_id).decode()
+        )
+
+        result = self.client_patch("/json/realm", req)
+        self.assert_json_success(result)
+        realm = get_realm("zulip")
+        assert realm.signup_notifications_stream is not None
+        self.assertEqual(realm.signup_notifications_stream.id, new_signup_notifications_stream_id)
+
         invalid_signup_notifications_stream_id = 1234
         req = dict(
             signup_notifications_stream_id=orjson.dumps(

zerver/views/realm.py

@@ -383,7 +383,7 @@ def update_realm(
         new_notifications_stream = None
         if notifications_stream_id >= 0:
             (new_notifications_stream, sub) = access_stream_by_id(
-                user_profile, notifications_stream_id
+                user_profile, notifications_stream_id, allow_realm_admin=True
             )
         do_set_realm_notifications_stream(
             realm, new_notifications_stream, notifications_stream_id, acting_user=user_profile
@@ -397,7 +397,7 @@ def update_realm(
         new_signup_notifications_stream = None
         if signup_notifications_stream_id >= 0:
             (new_signup_notifications_stream, sub) = access_stream_by_id(
-                user_profile, signup_notifications_stream_id
+                user_profile, signup_notifications_stream_id, allow_realm_admin=True
             )
         do_set_realm_signup_notifications_stream(
             realm,