chore(openai): fix tests (#39972)

.github/workflows/_release.yml

@@ -737,7 +737,9 @@ jobs:
           # Run tests
           uv sync --group test --group test_integration
           uv pip install $PRERELEASE_FLAG ../../core/dist/*.whl
-          make test
+
+          env -u LANGSMITH_GATEWAY -u LANGSMITH_GATEWAY_API_KEY -u OPENAI_API_KEY make test
+
           make integration_tests
 
   # Test external packages that depend on langchain-core/langchain against the new release

libs/partners/openai/tests/unit_tests/conftest.py

@@ -0,0 +1,35 @@
+"""Shared fixtures for `langchain-openai` unit tests."""
+
+import pytest
+
+# Set by CI (and by developers routing local traffic through the LangSmith
+# gateway). `ChatOpenAI` resolves these at construction time and swaps in the
+# gateway base URL and key, which flips `_uses_gateway` and diverts mocked
+# clients down the `with_raw_response` path.
+_GATEWAY_VARS = (
+    "LANGSMITH_GATEWAY",
+    "LANGSMITH_GATEWAY_API_KEY",
+    "LANGSMITH_API_KEY",
+)
+
+_PROVIDER_VARS = (
+    "OPENAI_BASE_URL",
+    "OPENAI_API_BASE",
+    "OPENAI_ORG_ID",
+    "OPENAI_ORGANIZATION",
+    "OPENAI_PROXY",
+)
+
+
+@pytest.fixture(autouse=True)
+def hermetic_env(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Isolate unit tests from ambient OpenAI and gateway configuration.
+
+    Unit tests run offline against mocked clients, so any real credential or
+    base URL in the environment can only change behavior for the worse. Tests
+    that exercise environment handling override these with their own
+    `monkeypatch` calls, which still take precedence.
+    """
+    for var in (*_GATEWAY_VARS, *_PROVIDER_VARS):
+        monkeypatch.delenv(var, raising=False)
+    monkeypatch.setenv("OPENAI_API_KEY", "foo")

libs/partners/openai/tests/unit_tests/embeddings/test_base.py

@@ -1,4 +1,3 @@
-import os
 from typing import Any
 from unittest.mock import Mock, patch
 
@@ -7,8 +6,6 @@ from pydantic import SecretStr
 
 from langchain_openai import OpenAIEmbeddings
 
-os.environ["OPENAI_API_KEY"] = "foo"
-
 
 def test_openai_invalid_model_kwargs() -> None:
     with pytest.raises(ValueError):

libs/partners/openai/tests/unit_tests/llms/test_base.py

@@ -1,13 +1,9 @@
-import os
-
 import pytest
 from langchain_core.outputs import GenerationChunk
 
 from langchain_openai import OpenAI
 from langchain_openai.llms.base import _stream_response_to_generation_chunk
 
-os.environ["OPENAI_API_KEY"] = "foo"
-
 OPENAI_LLM_TEST_MODEL = "gpt-3.5-turbo-instruct"