fix: keep display names out of pack file paths

tests/test_pack_file_names.py

@@ -0,0 +1,52 @@
+"""A display name never becomes a path inside the output directory.
+
+fbneo_cps12 is called 'FinalBurn Neo (CPS-1/CPS-2)': the slash made the
+emulator and system packs write into a directory that does not exist, while
+verify reported the same scope OK.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+from generate_pack import _name_part, generate_emulator_pack  # noqa: E402
+
+
+class PackFileNames(unittest.TestCase):
+    def test_separators_and_reserved_characters_are_replaced(self):
+        self.assertEqual(_name_part("FinalBurn Neo (CPS-1/CPS-2)"), "FinalBurnNeo(CPS-1-CPS-2)")
+        self.assertEqual(_name_part('a\\b:c*d?"e<f>g|h', "_"), "a-b-c-d--e-f-g-h")
+
+    def test_an_emulator_named_with_a_slash_writes_its_pack(self):
+        with tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp") as tmp:
+            emulators = Path(tmp) / "emulators"
+            out = Path(tmp) / "out"
+            emulators.mkdir()
+            out.mkdir()
+            rom = Path(tmp) / "demo.bin"
+            rom.write_bytes(b"demo")
+            sha1 = hashlib.sha1(b"demo").hexdigest()
+            (emulators / "demo.yml").write_text(
+                'emulator: "Demo (A/B)"\ntype: libretro\nsystems: [demo]\n'
+                f'files:\n  - name: demo.bin\n    sha1: "{sha1}"\n'
+            )
+            db = {
+                "files": {sha1: {"path": str(rom), "name": "demo.bin", "size": 4,
+                                 "md5": hashlib.md5(b"demo").hexdigest()}},
+                "indexes": {"by_name": {"demo.bin": [sha1]}, "by_md5": {}},
+            }
+            result = generate_emulator_pack(
+                ["demo"], str(emulators), db, "bios", str(out), zip_contents={},
+            )
+            self.assertTrue(result and Path(result).parent == out, result)
+
+
+if __name__ == "__main__":
+    unittest.main()