test(tools): regression test for Windows creationflags double-pass (#29651)

tests/tools/test_local_popen_creationflags.py

@@ -0,0 +1,106 @@
+"""Regression tests for Windows creationflags in LocalEnvironment._run_bash.
+
+PR #29059 removed a duplicate explicit ``creationflags=`` kwarg that was
+passed alongside ``**_popen_kwargs`` (issue #29651 / #28920).  These tests
+ensure ``subprocess.Popen`` receives ``creationflags`` exactly once.
+
+See: https://github.com/NousResearch/hermes-agent/issues/29651
+See: https://github.com/NousResearch/hermes-agent/pull/29059
+"""
+
+import inspect
+import re
+import sys
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from hermes_cli._subprocess_compat import windows_hide_flags
+from tools.environments.local import LocalEnvironment
+
+
+def _make_fake_popen(captured: dict):
+    """Return a fake Popen that records kwargs (including creationflags)."""
+
+    def fake_popen(cmd, **kwargs):
+        captured["cmd"] = cmd
+        captured["kwargs"] = dict(kwargs)
+        proc = MagicMock()
+        proc.poll.return_value = 0
+        proc.returncode = 0
+        proc.stdout = MagicMock(
+            __iter__=lambda s: iter([]),
+            __next__=lambda s: (_ for _ in ()).throw(StopIteration),
+        )
+        proc.stdin = MagicMock()
+        proc.pid = 12345
+        return proc
+
+    return fake_popen
+
+
+class TestLocalPopenCreationflags:
+    """LocalEnvironment must not pass creationflags twice to subprocess.Popen."""
+
+    def test_run_bash_passes_creationflags_once_on_windows(self, monkeypatch, tmp_path):
+        """Simulated Windows: Popen kwargs contain a single creationflags entry."""
+        monkeypatch.setattr("tools.environments.local._IS_WINDOWS", True)
+        captured = {}
+
+        env = LocalEnvironment(cwd=str(tmp_path), timeout=10)
+        with patch("tools.environments.local._find_bash", return_value="/bin/bash"), \
+             patch("subprocess.Popen", side_effect=_make_fake_popen(captured)):
+            env._run_bash("echo hello")
+
+        kwargs = captured["kwargs"]
+        assert "creationflags" in kwargs
+        assert kwargs["creationflags"] == windows_hide_flags()
+        # Duplicate explicit + spread would raise at call time; ensure one source.
+        assert list(kwargs).count("creationflags") == 1
+
+    @pytest.mark.skipif(sys.platform == "win32", reason="POSIX os.setsid branch")
+    def test_run_bash_omits_creationflags_on_posix(self, monkeypatch, tmp_path):
+        """Non-Windows: no creationflags kwarg (POSIX uses preexec_fn instead)."""
+        monkeypatch.setattr("tools.environments.local._IS_WINDOWS", False)
+        captured = {}
+
+        env = LocalEnvironment(cwd=str(tmp_path), timeout=10)
+        with patch("tools.environments.local._find_bash", return_value="/bin/bash"), \
+             patch("subprocess.Popen", side_effect=_make_fake_popen(captured)):
+            env._run_bash("echo hello")
+
+        assert "creationflags" not in captured["kwargs"]
+
+    def test_duplicate_explicit_and_spread_creationflags_raises(self):
+        """Document the failure mode PR #29059 fixed (explicit + **_popen_kwargs)."""
+        import subprocess
+
+        extra = {"creationflags": windows_hide_flags()}
+        with pytest.raises(
+            TypeError,
+            match="multiple values for keyword argument 'creationflags'",
+        ):
+            subprocess.Popen(
+                ["echo"],
+                creationflags=0x08000000,
+                **extra,
+            )
+
+
+class TestLocalRunBashSourceGuard:
+    """Static guard: _run_bash must not combine explicit creationflags= with **_popen_kwargs."""
+
+    def test_run_bash_no_duplicate_creationflags_in_source(self):
+        root = Path(__file__).resolve().parents[2]
+        source = inspect.getsource(
+            __import__("tools.environments.local", fromlist=["LocalEnvironment"]).LocalEnvironment._run_bash
+        )
+        # Explicit kwarg before spread caused #29651.
+        assert re.search(
+            r"creationflags\s*=",
+            source,
+        ) is None, (
+            "_run_bash must not pass creationflags= explicitly; use **_popen_kwargs only"
+        )
+        assert "**_popen_kwargs" in source