zilencer: Improve json error when plan doesn't allow push notifs.

This allows the self-hosted server to explicitly test for that exception
and catch and log it nicely.

zerver/lib/exceptions.py

@@ -51,6 +51,7 @@ class ErrorCode(Enum):
     STREAM_WILDCARD_MENTION_NOT_ALLOWED = auto()
     REMOTE_BILLING_UNAUTHENTICATED_USER = auto()
     REMOTE_REALM_SERVER_MISMATCH_ERROR = auto()
+    PUSH_NOTIFICATIONS_DISALLOWED = auto()
 
 
 class JsonableError(Exception):

zerver/tests/test_push_notifications.py

@@ -829,8 +829,11 @@ class PushBouncerNotificationTest(BouncerTestCase):
             payload,
             content_type="application/json",
         )
-        self.assert_json_error(result, "Your plan doesn't allow sending push notifications.")
-        self.assertEqual(orjson.loads(result.content)["code"], "BAD_REQUEST")
+        self.assert_json_error(
+            result,
+            "Your plan doesn't allow sending push notifications. Reason provided by the server: Missing data",
+        )
+        self.assertEqual(orjson.loads(result.content)["code"], "PUSH_NOTIFICATIONS_DISALLOWED")
 
         human_counts = {
             str(UserProfile.ROLE_REALM_ADMINISTRATOR): 1,
@@ -854,8 +857,11 @@ class PushBouncerNotificationTest(BouncerTestCase):
             payload,
             content_type="application/json",
         )
-        self.assert_json_error(result, "Your plan doesn't allow sending push notifications.")
-        self.assertEqual(orjson.loads(result.content)["code"], "BAD_REQUEST")
+        self.assert_json_error(
+            result,
+            "Your plan doesn't allow sending push notifications. Reason provided by the server: No plan many users",
+        )
+        self.assertEqual(orjson.loads(result.content)["code"], "PUSH_NOTIFICATIONS_DISALLOWED")
 
         # Check that sponsored realms are allowed to send push notifications.
         remote_server.plan_type = RemoteRealm.PLAN_TYPE_COMMUNITY

zilencer/views.py

@@ -472,6 +472,16 @@ class OldZulipServerError(JsonableError):
         self._msg: str = msg
 
 
+class PushNotificationsDisallowedError(JsonableError):
+    code = ErrorCode.PUSH_NOTIFICATIONS_DISALLOWED
+
+    def __init__(self, reason: str) -> None:
+        msg = _(
+            "Your plan doesn't allow sending push notifications. Reason provided by the server: {reason}"
+        ).format(reason=reason)
+        super().__init__(msg)
+
+
 @has_request_variables
 def remote_server_notify_push(
     request: HttpRequest,
@@ -502,7 +512,8 @@ def remote_server_notify_push(
         if server.last_api_feature_level is None:
             raise OldZulipServerError(_("Your plan doesn't allow sending push notifications."))
         else:
-            raise JsonableError(_("Your plan doesn't allow sending push notifications."))
+            reason = push_status.message
+            raise PushNotificationsDisallowedError(reason=reason)
 
     android_devices = list(
         RemotePushDeviceToken.objects.filter(