fix: refuse an unknown emulator for a hash pack

scripts/generate_pack.py

@@ -1860,23 +1860,22 @@ def generate_md5_pack(
     emu_display = ""
     if emulator_name and emulators_dir:
         profiles = load_emulator_profiles(emulators_dir, skip_aliases=False)
-        if emulator_name in profiles:
-            # The same gate as --emulator: a core with no standalone build
-            # has no standalone layout, and a pack named for one would be
-            # the libretro pack under a name that promises otherwise.
-            try:
-                (_name, profile), = select_emulator_profiles(
-                    [emulator_name], profiles, standalone
-                )
-            except ProfileSelectionError as exc:
-                print(f"Error: {exc}", file=sys.stderr)
-                return None
-            emu_display = profile.get("emulator", emulator_name)
-            emu_pack_structure = profile.get("pack_structure")
-            for fe in profile.get("files", []):
-                plat_file_index[fe.get("name", "").lower()] = fe
-                for alias in fe.get("aliases", []):
-                    plat_file_index[alias.lower()] = fe
+        # The same gate as --emulator, unknown names included: a typo or a
+        # buildbot name gave a generic pack in the layout of no emulator. A
+        # core with no standalone build has no standalone layout either.
+        try:
+            (_name, profile), = select_emulator_profiles(
+                [emulator_name], profiles, standalone
+            )
+        except ProfileSelectionError as exc:
+            print(f"Error: {exc}", file=sys.stderr)
+            return None
+        emu_display = profile.get("emulator", emulator_name)
+        emu_pack_structure = profile.get("pack_structure")
+        for fe in profile.get("files", []):
+            plat_file_index[fe.get("name", "").lower()] = fe
+            for alias in fe.get("aliases", []):
+                plat_file_index[alias.lower()] = fe
 
     context_name = plat_display if platform_name else (emu_display or "Custom")
     # --standalone changes the destination layout, so a run with it must not

tests/test_md5_pack_context.py

@@ -0,0 +1,54 @@
+"""A custom pack built from hashes follows the emulator it names, or refuses.
+
+`--from-md5 --emulator` accepted any name: an unknown one produced a generic
+pack in the layout of no emulator, rc 0, where `--emulator` alone refuses it.
+With a known one and `--standalone`, a profile without pack_structure kept
+the bare file names under a pack called Standalone.
+"""
+
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+import tempfile
+import unittest
+import zipfile
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+
+
+def _pack(*options: str) -> tuple[subprocess.CompletedProcess, list[str]]:
+    with tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp") as out:
+        proc = subprocess.run(
+            [sys.executable, "scripts/generate_pack.py", *options, "--offline",
+             "--output-dir", out],
+            cwd=REPO_ROOT, capture_output=True, text=True, timeout=600, check=False,
+        )
+        names = []
+        for archive in Path(out).glob("*.zip"):
+            with zipfile.ZipFile(archive) as zf:
+                names.extend(zf.namelist())
+    return proc, names
+
+
+class TheEmulatorContextIsChecked(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        db_path = REPO_ROOT / "database.json"
+        if not db_path.exists():
+            raise unittest.SkipTest("database.json is not built")
+        (REPO_ROOT / "tmp").mkdir(exist_ok=True)
+        cls.db = json.loads(db_path.read_text(encoding="utf-8"))
+
+    def test_an_unknown_emulator_is_refused(self):
+        md5 = next(iter(self.db["files"].values()))["md5"]
+        proc, names = _pack("--from-md5", md5, "--emulator", "no_such_core")
+        self.assertNotEqual(proc.returncode, 0, proc.stdout)
+        self.assertIn("not found", proc.stderr)
+        self.assertEqual(names, [])
+
+
+if __name__ == "__main__":
+    unittest.main()