fix: keep the md5 a mister entry already holds

A BiosDB entry is one record: md5, size and url describe one dump. The
first md5 the truth accepts replaced an accepted one with no change
reported. The exporter now writes record_hash, as RomM and System.dat do.

scripts/exporter/misterfpga_exporter.py

@@ -86,8 +86,14 @@ class Exporter(BaseExporter):
         return super().states(fe, field_name)
 
     def written(self, fe: NativeFile, field_name: str) -> str:
-        """An entry is checked against one md5, the first accepted."""
-        return fe.hash(field_name)
+        """An entry is one record: its md5, size and url describe one dump.
+
+        The first value the truth accepts replaced MiSTer's own accepted
+        md5 while the url still served MiSTer's dump, which the Downloader
+        then refused (fetch_file_worker.py:127), and the report said
+        nothing. record_hash keeps the platform's value when it is accepted.
+        """
+        return fe.record_hash(field_name)
 
     def _by_path(self, systems: dict[str, NativeSystem]) -> dict[str, object]:
         indexed: dict[str, object] = {}
@@ -119,7 +125,7 @@ class Exporter(BaseExporter):
             fe = indexed.get(path)
             if fe is None:
                 continue
-            md5 = fe.hash("md5")
+            md5 = self.written(fe, "md5")
             if not md5:
                 # The record is checked by its md5: where the truth takes the
                 # entry without one, a new size beside the old hash describes
@@ -185,7 +191,7 @@ class Exporter(BaseExporter):
         indexed = self._by_path(systems)
         for path, fe in indexed.items():
             declared = files.get(path)
-            md5 = fe.hash("md5")
+            md5 = self.written(fe, "md5")
             if (
                 declared is not None and md5 and declared.get("hash") != md5
                 and path not in getattr(self, "_unsized", [])

tests/test_exporters.py

@@ -1849,6 +1849,27 @@ class MisterDatabaseComesBackAsWritten(unittest.TestCase):
         self.assertEqual(len(exporter.withheld()), 1)
         self.assertEqual(exporter.validate(systems, produced), [])
 
+    def test_an_accepted_hash_is_not_swapped_for_another(self):
+        """The url serves MiSTer's dump, and the truth accepts it among two.
+        The first accepted md5 went in its place with no change reported,
+        and the Downloader refused every install of the file."""
+        database = {"db_id": "bios_db", "files": {
+            "games/X/boot.rom": {"hash": "b" * 32, "size": 10, "url": "u"},
+        }}
+        original = json.dumps(database)
+        scraped = {"systems": {"x": {"files": [{
+            "name": "boot.rom", "destination": "X/boot.rom", "md5": "b" * 32, "size": 10,
+        }]}}}
+        truth = {"systems": {"x": {"files": [{
+            "name": "boot.rom", "path": "X/boot.rom", "md5": ["a" * 32, "b" * 32],
+            "size": 10, "_cores": ["x"],
+        }]}}}
+        exporter = discover_exporters()["misterfpga"]()
+        systems, report = build_native_model(truth, scraped)
+        produced = exporter.render(systems, report, {"bios_db.json": original}, scraped)
+        self.assertEqual(produced["bios_db.json"], original)
+        self.assertEqual(exporter.validate(systems, produced), [])
+
     def test_an_empty_truth_hands_back_the_database(self):
         archive = UPSTREAM_CACHE / "misterfpga" / "bios_db.json.zip"
         if not archive.exists():