fix: stop game data being served by another game's file

tests/test_game_data_homonyms.py

@@ -0,0 +1,115 @@
+"""Game data laid out in a directory is not served by another game's file.
+
+Engines read generic names from their own tree: `pak0.pak` is Quake II's
+under `baseq2/` and Half-Life's under `valve/`. The name step of the resolver
+ignores directories, so once one of them is collected every other entry of
+that name resolves to it and a pack ships the wrong game's bytes under the
+right path. The collection stores such a file under the tail the engine
+reads (`.../baseq2/pak0.pak`), which lets its own entry resolve by path; an
+entry that only reaches the same file by its bare name is a homonym, and
+carries `unsourceable:` until its own bytes are held.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+from common import (  # noqa: E402
+    build_zip_contents_index,
+    load_data_dir_registry,
+    load_database,
+    load_emulator_profiles,
+    resolve_local_file,
+)
+
+
+def homonyms(claims: list[tuple[str, str, str, str]]) -> list[tuple[str, str, str]]:
+    """(profile, destination, file) for name-only claims on a file that
+    another entry reaches by its path.
+
+    claims: (profile, destination, status, local file).
+    """
+    by_path = {local for _, _, status, local in claims if status == "path_exact"}
+    found = []
+    for profile, dest, status, local in claims:
+        if status != "name_exact" or local not in by_path:
+            continue
+        if local.casefold().endswith("/" + dest.casefold()):
+            continue
+        if local.rsplit("/", 1)[-1].casefold() != dest.rsplit("/", 1)[-1].casefold():
+            # Reached through an alias: the profile says the two are one file.
+            continue
+        found.append((profile, dest, local))
+    return sorted(found)
+
+
+class HomonymRule(unittest.TestCase):
+    def test_a_name_claim_on_a_file_another_entry_reaches_by_path_is_named(self):
+        claims = [
+            ("quake2", "baseq2/pak0.pak", "path_exact", "bios/Q2/baseq2/pak0.pak"),
+            ("halflife", "valve/pak0.pak", "name_exact", "bios/Q2/baseq2/pak0.pak"),
+        ]
+        self.assertEqual(
+            homonyms(claims), [("halflife", "valve/pak0.pak", "bios/Q2/baseq2/pak0.pak")]
+        )
+
+    def test_a_file_only_ever_found_by_name_is_not_judged(self):
+        claims = [
+            ("mame2003", "mame2003/cheat.dat", "name_exact", "bios/Arcade/cheat.dat"),
+            ("mame2010", "mame2010/cheat.dat", "name_exact", "bios/Arcade/cheat.dat"),
+        ]
+        self.assertEqual(homonyms(claims), [])
+
+    def test_a_declared_alias_is_the_profile_speaking(self):
+        claims = [
+            ("m", "crosshair/cross7.png", "path_exact", "bios/m/crosshair/cross7.png"),
+            ("m", "crosshair/cross8.png", "name_exact", "bios/m/crosshair/cross7.png"),
+        ]
+        self.assertEqual(homonyms(claims), [])
+
+    def test_two_entries_sharing_a_path_agree(self):
+        claims = [
+            ("a", "etmain/pak1.pk3", "path_exact", "bios/ET/etmain/pak1.pk3"),
+            ("b", "etmain/pak1.pk3", "path_exact", "bios/ET/etmain/pak1.pk3"),
+        ]
+        self.assertEqual(homonyms(claims), [])
+
+
+class CollectionCarriesNoGameDataHomonym(unittest.TestCase):
+    def test_the_profiles_resolve_no_game_data_to_another_game(self):
+        database = REPO_ROOT / "database.json"
+        if not database.is_file():
+            self.skipTest("no database.json")
+        previous = os.getcwd()
+        os.chdir(REPO_ROOT)
+        try:
+            db = load_database(str(database))
+            profiles = load_emulator_profiles("emulators", skip_aliases=False)
+            zip_index = build_zip_contents_index(db)
+            registry = load_data_dir_registry("platforms")
+            claims = []
+            for name, profile in sorted(profiles.items()):
+                for entry in profile.get("files") or []:
+                    if entry.get("category") != "game_data" or entry.get("unsourceable"):
+                        continue
+                    dest = str(entry.get("path") or entry.get("name") or "")
+                    if "/" not in dest.strip("/"):
+                        continue
+                    local, status = resolve_local_file(
+                        entry, db, zip_index, dest_hint=dest, data_dir_registry=registry
+                    )
+                    if local:
+                        claims.append((name, dest, status, local))
+        finally:
+            os.chdir(previous)
+        self.assertEqual(homonyms(claims), [])
+
+
+if __name__ == "__main__":
+    unittest.main()