chore: import upstream snapshot with attribution

tests/tools/interactive_shell/test_subprocess_primitives.py

@@ -0,0 +1,57 @@
+"""Unit tests for pure subprocess helpers in tools.interactive_shell.subprocess."""
+
+from __future__ import annotations
+
+import subprocess
+import tempfile
+import threading
+
+import pytest
+
+from tools.interactive_shell.subprocess import (
+    read_diag,
+    subprocess_env_with_width,
+    terminate_child_process,
+    watch_subprocess_until_exit,
+)
+
+
+def test_subprocess_env_with_width_reserves_prefix(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("LINES", raising=False)
+    env = subprocess_env_with_width(columns=100, lines=30)
+    assert env["COLUMNS"] == "81"
+    assert env["LINES"] == "30"
+
+
+def test_subprocess_env_with_width_preserves_existing_lines(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setenv("LINES", "24")
+    env = subprocess_env_with_width(columns=100, lines=30)
+    assert env["LINES"] == "24"
+
+
+def test_read_diag_strips_ansi() -> None:
+    with tempfile.SpooledTemporaryFile(max_size=4096) as buf:
+        buf.write(b"\x1b[31merror\x1b[0m")
+        buf.seek(0)
+        assert read_diag(buf) == "error"
+
+
+def test_terminate_child_process_noop_when_exited() -> None:
+    proc = subprocess.Popen(["true"])
+    proc.wait()
+    terminate_child_process(proc)
+
+
+def test_watch_subprocess_until_exit_on_cancel() -> None:
+    proc = subprocess.Popen(["sleep", "30"])
+    cancel = threading.Event()
+    cancel.set()
+    result = watch_subprocess_until_exit(
+        proc,
+        cancel_event=cancel,
+        timeout_seconds=60,
+    )
+    assert result.cancelled
+    assert result.terminated_by_watcher