fix(f173c903-1467-4c00-aa7f-bcf48007d079): attach CI LangSmith metadata before pytest runs

libs/standard-tests/langchain_tests/_langsmith_plugin.py

@@ -23,7 +23,6 @@ import sys
 import warnings
 from typing import TYPE_CHECKING, Any
 
-import pytest
 from langsmith.run_helpers import tracing_context
 
 if TYPE_CHECKING:
@@ -84,8 +83,22 @@ def _langsmith_ci_cm() -> Iterator[None]:
         yield
 
 
-@pytest.fixture(scope="session", autouse=True)
-def _langsmith_ci_context() -> Iterator[None]:
-    """Apply `LANGSMITH_TAGS`/`LANGSMITH_METADATA` to traces in this session."""
-    with _langsmith_ci_cm():
-        yield
+_langsmith_ci_context: contextlib.ExitStack | None = None
+
+
+def pytest_configure() -> None:
+    """Apply `LANGSMITH_TAGS`/`LANGSMITH_METADATA` to traces."""
+    global _langsmith_ci_context  # noqa: PLW0603
+
+    if _langsmith_ci_context is None:
+        _langsmith_ci_context = contextlib.ExitStack()
+        _langsmith_ci_context.enter_context(_langsmith_ci_cm())
+
+
+def pytest_unconfigure() -> None:
+    """Restore the previous LangSmith tracing context."""
+    global _langsmith_ci_context  # noqa: PLW0603
+
+    if _langsmith_ci_context is not None:
+        _langsmith_ci_context.close()
+        _langsmith_ci_context = None

libs/standard-tests/tests/unit_tests/test_langsmith_plugin.py

@@ -129,22 +129,23 @@ class TestContextManager:
 
 
 class TestPluginDiscovery:
-    """End-to-end: the `pytest11` entry point wires up the autouse fixture."""
+    """End-to-end: the `pytest11` entry point wires up the plugin hooks."""
 
-    def test_autouse_fixture_applies_env_in_subprocess(
+    def test_plugin_hooks_apply_env_in_subprocess(
         self, pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch
     ) -> None:
         monkeypatch.setenv("GITHUB_ACTIONS", "true")
         monkeypatch.setenv("LANGSMITH_TAGS", "discovered,from-entrypoint")
         monkeypatch.delenv("LANGSMITH_METADATA", raising=False)
-        pytester.makepyfile(
+        pytester.makeconftest(
             dedent("""
                 from langsmith.run_helpers import get_tracing_context
 
-                def test_tags_visible_via_autouse_fixture():
+                def pytest_runtest_setup(item):
                     ctx = get_tracing_context()
                     assert ctx["tags"] == ["discovered", "from-entrypoint"]
             """),
         )
+        pytester.makepyfile("def test_tags_visible_before_test_setup(): pass")
         result = pytester.runpytest_subprocess("-q")
         result.assert_outcomes(passed=1)