Reject invalid preset CLI entries (#1579)

* Reject invalid preset CLI entries

* Use modern preset CLI test loader

tests/test_preset_cli_invalid_entries.py

@@ -0,0 +1,29 @@
+import importlib.machinery
+import importlib.util
+from pathlib import Path
+
+
+def _load_preset_cli():
+    path = Path(__file__).resolve().parent.parent / "scripts" / "odysseus-preset"
+    loader = importlib.machinery.SourceFileLoader("odysseus_preset_invalid_entries", str(path))
+    spec = importlib.util.spec_from_loader(loader.name, loader)
+    module = importlib.util.module_from_spec(spec)
+    loader.exec_module(module)
+    return module
+
+
+def test_entry_or_fail_rejects_non_object_entries():
+    cli = _load_preset_cli()
+
+    try:
+        cli._entry_or_fail({"broken": "raw prompt"}, "broken")
+    except SystemExit as exc:
+        assert exc.code == 1
+    else:
+        raise AssertionError("expected invalid preset entry to exit")
+
+
+def test_entry_or_fail_returns_valid_entry():
+    cli = _load_preset_cli()
+
+    assert cli._entry_or_fail({"ok": {"name": "ok"}}, "ok") == {"name": "ok"}