Fix errors raising TransportProtocolError with the graphql-ws protocol (#299)

Author: leszekhanusz

gql/transport/websockets.py

@@ -272,6 +272,7 @@ def _parse_answer_graphqlws(
             - instead of a unidirectional keep-alive (ka) message from server to client,
               there is now the possibility to send bidirectional ping/pong messages
             - connection_ack has an optional payload
+            - the 'error' answer type returns a list of errors instead of a single error
         """
 
         answer_type: str = ""
@@ -288,11 +289,11 @@ def _parse_answer_graphqlws(
 
                     payload = json_answer.get("payload")
 
-                    if not isinstance(payload, dict):
-                        raise ValueError("payload is not a dict")
-
                     if answer_type == "next":
 
+                        if not isinstance(payload, dict):
+                            raise ValueError("payload is not a dict")
+
                         if "errors" not in payload and "data" not in payload:
                             raise ValueError(
                                 "payload does not contain 'data' or 'errors' fields"
@@ -309,8 +310,11 @@ def _parse_answer_graphqlws(
 
                     elif answer_type == "error":
 
+                        if not isinstance(payload, list):
+                            raise ValueError("payload is not a list")
+
                         raise TransportQueryError(
-                            str(payload), query_id=answer_id, errors=[payload]
+                            str(payload[0]), query_id=answer_id, errors=payload
                         )
 
             elif answer_type in ["ping", "pong", "connection_ack"]:

tests/test_graphqlws_exceptions.py

@@ -1,6 +1,4 @@
 import asyncio
-import json
-import types
 from typing import List
 
 import pytest
@@ -125,49 +123,29 @@ async def test_graphqlws_server_does_not_send_ack(
             pass
 
 
-invalid_payload_server_answer = (
-    '{"type":"error","id":"1","payload":{"message":"Must provide document"}}'
+invalid_query_server_answer = (
+    '{"id":"1","type":"error","payload":[{"message":"Cannot query field '
+    '\\"helo\\" on type \\"Query\\". Did you mean \\"hello\\"?",'
+    '"locations":[{"line":2,"column":3}]}]}'
 )
 
 
-async def server_invalid_payload(ws, path):
+async def server_invalid_query(ws, path):
     await WebSocketServerHelper.send_connection_ack(ws)
     result = await ws.recv()
     print(f"Server received: {result}")
-    await ws.send(invalid_payload_server_answer)
+    await ws.send(invalid_query_server_answer)
     await WebSocketServerHelper.wait_connection_terminate(ws)
     await ws.wait_closed()
 
 
 @pytest.mark.asyncio
-@pytest.mark.parametrize("graphqlws_server", [server_invalid_payload], indirect=True)
-@pytest.mark.parametrize("query_str", [invalid_query_str])
-async def test_graphqlws_sending_invalid_payload(
-    event_loop, client_and_graphqlws_server, query_str
-):
+@pytest.mark.parametrize("graphqlws_server", [server_invalid_query], indirect=True)
+async def test_graphqlws_sending_invalid_query(event_loop, client_and_graphqlws_server):
 
     session, server = client_and_graphqlws_server
 
-    # Monkey patching the _send_query method to send an invalid payload
-
-    async def monkey_patch_send_query(
-        self, document, variable_values=None, operation_name=None,
-    ) -> int:
-        query_id = self.next_query_id
-        self.next_query_id += 1
-
-        query_str = json.dumps(
-            {"id": str(query_id), "type": "subscribe", "payload": "BLAHBLAH"}
-        )
-
-        await self._send(query_str)
-        return query_id
-
-    session.transport._send_query = types.MethodType(
-        monkey_patch_send_query, session.transport
-    )
-
-    query = gql(query_str)
+    query = gql("{helo}")
 
     with pytest.raises(TransportQueryError) as exc_info:
         await session.execute(query)
@@ -178,7 +156,10 @@ async def monkey_patch_send_query(
 
     error = exception.errors[0]
 
-    assert error["message"] == "Must provide document"
+    assert (
+        error["message"]
+        == 'Cannot query field "helo" on type "Query". Did you mean "hello"?'
+    )
 
 
 not_json_answer = ["BLAHBLAH"]
@@ -188,6 +169,7 @@ async def monkey_patch_send_query(
 missing_id_answer_3 = ['{"type": "complete"}']
 data_without_payload = ['{"type": "next", "id":"1"}']
 error_without_payload = ['{"type": "error", "id":"1"}']
+error_with_payload_not_a_list = ['{"type": "error", "id":"1", "payload": "NOT A LIST"}']
 payload_is_not_a_dict = ['{"type": "next", "id":"1", "payload": "BLAH"}']
 empty_payload = ['{"type": "next", "id":"1", "payload": {}}']
 sending_bytes = [b"\x01\x02\x03"]
@@ -205,6 +187,7 @@ async def monkey_patch_send_query(
         data_without_payload,
         error_without_payload,
         payload_is_not_a_dict,
+        error_with_payload_not_a_list,
         empty_payload,
         sending_bytes,
     ],