Better transport exception messages (#155)

Author: leszekhanusz

gql/transport/aiohttp.py

@@ -204,12 +204,20 @@ async def execute(
                     resp.raise_for_status()
 
                 except ClientResponseError as e:
-                    raise TransportServerError from e
+                    raise TransportServerError(str(e)) from e
 
-                raise TransportProtocolError("Server did not return a GraphQL result")
+                result_text = await resp.text()
+                raise TransportProtocolError(
+                    f"Server did not return a GraphQL result: {result_text}"
+                )
 
             if "errors" not in result and "data" not in result:
-                raise TransportProtocolError("Server did not return a GraphQL result")
+                result_text = await resp.text()
+                raise TransportProtocolError(
+                    "Server did not return a GraphQL result: "
+                    'No "data" or "error" keys in answer: '
+                    f"{result_text}"
+                )
 
             return ExecutionResult(errors=result.get("errors"), data=result.get("data"))
 

gql/transport/websockets.py

@@ -325,7 +325,7 @@ def _parse_answer(
 
         except ValueError as e:
             raise TransportProtocolError(
-                "Server did not return a GraphQL result"
+                f"Server did not return a GraphQL result: {answer}"
             ) from e
 
         return answer_type, answer_id, execution_result

tests/test_aiohttp.py

@@ -83,9 +83,11 @@ async def handler(request):
 
         query = gql(query1_str)
 
-        with pytest.raises(TransportServerError):
+        with pytest.raises(TransportServerError) as exc_info:
             await session.execute(query)
 
+        assert "500, message='Internal Server Error'" in str(exc_info.value)
+
 
 query1_server_error_answer = '{"errors": ["Error 1", "Error 2"]}'
 
@@ -114,15 +116,34 @@ async def handler(request):
 
 
 invalid_protocol_responses = [
-    "{}",
-    "qlsjfqsdlkj",
-    '{"not_data_or_errors": 35}',
+    {
+        "response": "{}",
+        "expected_exception": (
+            "Server did not return a GraphQL result: "
+            'No "data" or "error" keys in answer: {}'
+        ),
+    },
+    {
+        "response": "qlsjfqsdlkj",
+        "expected_exception": (
+            "Server did not return a GraphQL result: " "qlsjfqsdlkj"
+        ),
+    },
+    {
+        "response": '{"not_data_or_errors": 35}',
+        "expected_exception": (
+            "Server did not return a GraphQL result: "
+            'No "data" or "error" keys in answer: {"not_data_or_errors": 35}'
+        ),
+    },
 ]
 
 
 @pytest.mark.asyncio
-@pytest.mark.parametrize("response", invalid_protocol_responses)
-async def test_aiohttp_invalid_protocol(event_loop, aiohttp_server, response):
+@pytest.mark.parametrize("param", invalid_protocol_responses)
+async def test_aiohttp_invalid_protocol(event_loop, aiohttp_server, param):
+    response = param["response"]
+
     async def handler(request):
         return web.Response(text=response, content_type="application/json")
 
@@ -138,9 +159,11 @@ async def handler(request):
 
         query = gql(query1_str)
 
-        with pytest.raises(TransportProtocolError):
+        with pytest.raises(TransportProtocolError) as exc_info:
             await session.execute(query)
 
+        assert param["expected_exception"] in str(exc_info.value)
+
 
 @pytest.mark.asyncio
 async def test_aiohttp_subscribe_not_supported(event_loop, aiohttp_server):