test(sim): guard simulator shell scripts with bash -n + shellcheck

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/unit/test_sim_script.py

@@ -0,0 +1,42 @@
+"""Guard shell scripts in scripts/ against syntax regressions."""
+
+from __future__ import annotations
+
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+SCRIPTS = [
+    REPO_ROOT / "scripts" / "sim_cameras.sh",
+    REPO_ROOT / "scripts" / "download_mediamtx.sh",
+]
+
+
+@pytest.mark.parametrize("script", SCRIPTS, ids=lambda p: p.name)
+def test_script_exists(script: Path) -> None:
+    assert script.is_file(), f"missing script: {script}"
+
+
+@pytest.mark.parametrize("script", SCRIPTS, ids=lambda p: p.name)
+def test_bash_syntax(script: Path) -> None:
+    result = subprocess.run(
+        ["bash", "-n", str(script)],
+        capture_output=True,
+        text=True,
+    )
+    assert result.returncode == 0, f"bash -n failed:\n{result.stderr}"
+
+
+@pytest.mark.parametrize("script", SCRIPTS, ids=lambda p: p.name)
+def test_shellcheck(script: Path) -> None:
+    if shutil.which("shellcheck") is None:
+        pytest.skip("shellcheck not installed")
+    result = subprocess.run(
+        ["shellcheck", "--severity=warning", str(script)],
+        capture_output=True,
+        text=True,
+    )
+    assert result.returncode == 0, f"shellcheck failed:\n{result.stdout}\n{result.stderr}"