Revert back to old behavior: reject response when both 'result' and '…

…error' keys are present, as well as when both are missing

plugin/core/rpc.py

@@ -149,21 +149,22 @@ def on_transport_closed(self) -> None:
 
     def response_handler(self, response: 'Dict[str, Any]') -> None:
         request_id = int(response["id"])
-        result = response.get("result", None)
-        error = response.get("error", None)
         if self.settings.log_payloads:
-            debug('     ' + str(result))
+            debug('     ' + str(response.get("result", None)))
         handler, error_handler = self._response_handlers.pop(request_id, (None, None))
-        if error is not None:
+        if "result" in response and "error" not in response:
+            if handler:
+                handler(response["result"])
+            else:
+                debug("No handler found for id", request_id)
+        elif "result" not in response and "error" in response:
+            error = response["error"]
             if error_handler:
                 error_handler(error)
             else:
                 self._error_display_handler(error.get("message"))
         else:
-            if handler:
-                handler(result)
-            else:
-                debug("No handler found for id", request_id)
+            debug('invalid response payload', response)
 
     def on_request(self, request_method: str, handler: 'Callable') -> None:
         self._request_handlers[request_method] = handler

plugin/core/test_rpc.py

@@ -105,6 +105,28 @@ def test_client_request_with_none_response(self):
         self.assertEqual(len(responses), 1)
         self.assertEqual(len(errors), 0)
 
+    def test_client_should_reject_response_when_both_result_and_error_are_present(self):
+        transport = MockTransport(lambda x: '{"id": 1, "result": {"key": "value"}, "error": {"message": "oops"}}')
+        settings = MockSettings()
+        client = Client(transport, settings)
+        req = Request.initialize(dict())
+        responses = []
+        errors = []
+        client.send_request(req, lambda resp: responses.append(resp), lambda err: errors.append(err))
+        self.assertEqual(len(responses), 0)
+        self.assertEqual(len(errors), 0)
+
+    def test_client_should_reject_response_when_both_result_and_error_keys_are_not_present(self):
+        transport = MockTransport(lambda x: '{"id": 1}')
+        settings = MockSettings()
+        client = Client(transport, settings)
+        req = Request.initialize(dict())
+        responses = []
+        errors = []
+        client.send_request(req, lambda resp: responses.append(resp), lambda err: errors.append(err))
+        self.assertEqual(len(responses), 0)
+        self.assertEqual(len(errors), 0)
+
     def test_client_notification(self):
         transport = MockTransport(notify_pong)
         settings = MockSettings()