test_host_policy_uses_preexec_on_macos() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_shell_execution_policies.py lines 112–141

def test_host_policy_uses_preexec_on_macos(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
    fake_resource = _make_resource(with_prlimit=False)
    monkeypatch.setattr(_execution, "resource", fake_resource, raising=False)
    monkeypatch.setattr(sys, "platform", "darwin")

    captured: dict[str, Any] = {}

    def fake_launch(
        *_args: Any, preexec_fn: Callable[[], None] | None, start_new_session: bool, **_kwargs: Any
    ) -> subprocess.Popen[str]:
        captured["preexec_fn"] = preexec_fn
        captured["start_new_session"] = start_new_session
        return Mock(spec=subprocess.Popen, pid=4321)

    monkeypatch.setattr(_execution, "_launch_subprocess", fake_launch)

    policy = HostExecutionPolicy(cpu_time_seconds=5, memory_bytes=8192)
    env = {"PATH": os.environ.get("PATH", "")}
    policy.spawn(workspace=tmp_path, env=env, command=("/bin/sh",))

    preexec_fn = captured["preexec_fn"]
    assert callable(preexec_fn)
    assert captured["start_new_session"] is True

    preexec_fn()
    # macOS fallback should use setrlimit
    assert fake_resource.setrlimit_calls == [
        (fake_resource.RLIMIT_CPU, (5, 5)),
        (fake_resource.RLIMIT_AS, (8192, 8192)),
    ]