fix: count a core file filling a declaration

In existence mode the builder packs a core's file at a destination the
platform declares and does not hold, and counts the declaration met.
verify now reads the same placement and reports it OK, so both sides
agree on the platform's count.

tests/test_core_file_fills_declaration.py

@@ -0,0 +1,97 @@
+"""A core's file at a free platform destination answers an existence check.
+
+The builder packs a core extra at a destination the platform declares and
+does not hold, and in existence mode counts the declaration met: the
+frontend sees a file at the path. verify kept it MISSING, so the pack said
+1/1 OK and verify 0/1 for the same platform.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import io
+import os
+import shutil
+import sys
+import tempfile
+import unittest
+import zipfile
+from contextlib import redirect_stdout
+from pathlib import Path
+
+import yaml
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+from common import _emulator_profiles_cache, load_platform_config  # noqa: E402
+from generate_pack import generate_pack  # noqa: E402
+from verify import verify_platform  # noqa: E402
+
+
+class ACoreFileFillsAFreeDeclaration(unittest.TestCase):
+    def setUp(self):
+        _emulator_profiles_cache.clear()
+        (REPO_ROOT / "tmp").mkdir(exist_ok=True)
+        self.root = Path(tempfile.mkdtemp(dir=REPO_ROOT / "tmp"))
+        self.addCleanup(shutil.rmtree, self.root, True)
+        bios = self.root / "bios" / "Maker" / "Console"
+        bios.mkdir(parents=True)
+        data = b"HELD BOOT ROM"
+        (bios / "boot.bin").write_bytes(data)
+        sha1 = hashlib.sha1(data).hexdigest()
+        md5 = hashlib.md5(data).hexdigest()
+        self.db = {
+            "files": {sha1: {
+                "path": str(bios / "boot.bin"), "name": "boot.bin",
+                "md5": md5, "crc32": "", "size": len(data),
+            }},
+            "indexes": {
+                "by_md5": {md5: sha1}, "by_name": {"boot.bin": [sha1]},
+                "by_crc32": {}, "by_path_suffix": {},
+            },
+        }
+        self.platforms = self.root / "platforms"
+        self.emulators = self.root / "emulators"
+        self.platforms.mkdir()
+        self.emulators.mkdir()
+        (self.platforms / "fakeplat.yml").write_text(yaml.safe_dump({
+            "platform": "FakePlat",
+            "verification_mode": "existence",
+            "base_destination": "system",
+            "cores": ["fakecore"],
+            "systems": {"console-a": {"files": [
+                {"name": "zzz_absent.bin", "destination": "zzz_absent.bin",
+                 "required": True},
+            ]}},
+        }))
+        # The entry's name differs from the destination it fills, as
+        # descriptive names do ("MDA font ROM" at mda.rom).
+        (self.emulators / "fakecore.yml").write_text(yaml.safe_dump({
+            "emulator": "FakeCore", "type": "libretro", "cores": ["fakecore"],
+            "systems": ["console-a"],
+            "files": [{"name": "Fake boot ROM", "path": "zzz_absent.bin",
+                       "sha1": sha1, "required": True}],
+        }))
+        self.config = load_platform_config("fakeplat", str(self.platforms))
+
+    def test_verify_counts_what_the_pack_counts(self):
+        result = verify_platform(
+            self.config, self.db, str(self.emulators), supplemental_names=set(),
+        )
+        out = self.root / "out"
+        with redirect_stdout(io.StringIO()):
+            zip_path = generate_pack(
+                "fakeplat", str(self.platforms), self.db, str(self.root / "bios"),
+                str(out), emulators_dir=str(self.emulators), offline=True,
+            )
+        with zipfile.ZipFile(zip_path) as zf:
+            self.assertIn("zzz_absent.bin", zf.namelist())
+        self.assertEqual(result["status_counts"], {"ok": 1})
+        self.assertEqual(
+            [d["status"] for d in result["details"]], ["ok"],
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()