Fix parsing responses with null output

src/openai/lib/_parsing/_responses.py

@@ -58,7 +58,7 @@ def parse_response(
 ) -> ParsedResponse[TextFormatT]:
     output_list: List[ParsedResponseOutputItem[TextFormatT]] = []
 
-    for output in response.output:
+    for output in response.output or []:
         if output.type == "message":
             content_list: List[ParsedContent[TextFormatT]] = []
             for item in output.content:

tests/lib/responses/test_responses.py

@@ -7,7 +7,11 @@
 from inline_snapshot import snapshot
 
 from openai import OpenAI, AsyncOpenAI
+from openai._types import omit
 from openai._utils import assert_signatures_in_sync
+from openai._models import construct_type_unchecked
+from openai.types.responses import Response
+from openai.lib._parsing._responses import parse_response
 
 from ...conftest import base_url
 from ..snapshots import make_snapshot_request
@@ -41,6 +45,48 @@ def test_output_text(client: OpenAI, respx_mock: MockRouter) -> None:
     )
 
 
+def test_parse_response_handles_null_output() -> None:
+    response = construct_type_unchecked(
+        type_=Response,
+        value={
+            "id": "resp_test",
+            "object": "response",
+            "created_at": 0,
+            "status": "completed",
+            "background": False,
+            "error": None,
+            "incomplete_details": None,
+            "instructions": None,
+            "max_output_tokens": None,
+            "max_tool_calls": None,
+            "model": "gpt-test",
+            "output": None,
+            "parallel_tool_calls": True,
+            "previous_response_id": None,
+            "prompt_cache_key": None,
+            "reasoning": {"effort": None, "summary": None},
+            "safety_identifier": None,
+            "service_tier": "default",
+            "store": True,
+            "temperature": 1.0,
+            "text": {"format": {"type": "text"}, "verbosity": "medium"},
+            "tool_choice": "auto",
+            "tools": [],
+            "top_logprobs": 0,
+            "top_p": 1.0,
+            "truncation": "disabled",
+            "usage": None,
+            "user": None,
+            "metadata": {},
+        },
+    )
+
+    parsed = parse_response(text_format=omit, input_tools=omit, response=response)
+
+    assert parsed.output == []
+    assert parsed.to_dict()["output"] == []
+
+
 @pytest.mark.parametrize("sync", [True, False], ids=["sync", "async"])
 def test_stream_method_definition_in_sync(sync: bool, client: OpenAI, async_client: AsyncOpenAI) -> None:
     checking_client: OpenAI | AsyncOpenAI = client if sync else async_client