fix: attach profile aliases to a unique name only

scripts/generate_db.py

@@ -402,9 +402,11 @@ def _collect_all_aliases(files: dict) -> dict:
     """
     md5_to_sha1 = {}
     name_to_sha1 = {}
+    name_count: dict[str, int] = {}
     for sha1, entry in files.items():
         md5_to_sha1[entry["md5"]] = sha1
         name_to_sha1[entry["name"]] = sha1
+        name_count[entry["name"]] = name_count.get(entry["name"], 0) + 1
 
     aliases = {}
 
@@ -501,7 +503,10 @@ def _collect_all_aliases(files: dict) -> dict:
                         matched = sha1
                     elif md5 and md5 in md5_to_sha1:
                         matched = md5_to_sha1[md5]
-                    elif entry_name and entry_name in name_to_sha1:
+                    elif entry_name and name_count.get(entry_name) == 1:
+                        # A name carried by several files names none of them:
+                        # quasi88's disk.rom aliases went to whichever
+                        # disk.rom the scan met last, a Tandy CoCo ROM.
                         matched = name_to_sha1[entry_name]
                     if matched:
                         for alias_name in entry_aliases:

tests/test_db_aliases.py

@@ -0,0 +1,67 @@
+"""A profile's aliases attach to the file its name designates, or to none.
+
+generate_db matched an alias-carrying entry by name through a dict that
+kept the last file of that name. quasi88's disk.rom aliases (N88SUB.ROM,
+n88sub.rom) went to a Tandy CoCo disk.rom, and a name lookup for the PC-88
+disk ROM then served the CoCo one.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+import tempfile
+import types
+import unittest
+from pathlib import Path
+from unittest import mock
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+
+class _NoCoreInfo:
+    def fetch_requirements(self):
+        return []
+
+
+class AliasesNeedAnUnambiguousName(unittest.TestCase):
+    def _aliases(self, files: dict) -> dict:
+        import generate_db
+
+        stub = types.ModuleType("scraper.coreinfo_scraper")
+        stub.Scraper = _NoCoreInfo
+        with tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp") as tmp:
+            previous = os.getcwd()
+            os.chdir(tmp)
+            try:
+                Path("emulators").mkdir()
+                Path("emulators/x.yml").write_text(
+                    'files:\n  - name: "disk.rom"\n    aliases: ["n88sub.rom"]\n'
+                )
+                with mock.patch.dict(sys.modules, {"scraper.coreinfo_scraper": stub}):
+                    return generate_db._collect_all_aliases(files)
+            finally:
+                os.chdir(previous)
+
+    @staticmethod
+    def _file(name: str, path: str, md5: str) -> dict:
+        return {"name": name, "path": path, "md5": md5}
+
+    def test_homonyms_take_no_alias(self):
+        files = {
+            "a": self._file("disk.rom", "bios/NEC/PC-98/disk.rom", "m1"),
+            "b": self._file("disk.rom", "bios/Tandy/CoCo/disk.rom", "m2"),
+        }
+        aliases = self._aliases(files)
+        named = {a["name"] for entries in aliases.values() for a in entries}
+        self.assertNotIn("n88sub.rom", named)
+
+    def test_a_unique_name_still_carries_its_aliases(self):
+        files = {"a": self._file("disk.rom", "bios/NEC/PC-88/disk.rom", "m1")}
+        aliases = self._aliases(files)
+        self.assertEqual([a["name"] for a in aliases.get("a", [])], ["n88sub.rom"])
+
+
+if __name__ == "__main__":
+    unittest.main()