fix: count data directory readers in truth

LRPS2 reads pcsx2/resources/GameIndex.yaml through its data directory
and declares no file entry for it, so the truth entry other cores build
named armsx2 and yaps2 alone and hash_conflict missed LRPS2's copy. A
core whose data directory holds a file at an entry's path now folds in
as a reader with the cached copy's hashes, unless the profile lists what
it reads under that tree (yaps2, pcee2).

tests/test_truth_data_dir_readers.py

@@ -0,0 +1,98 @@
+"""A core that reads a file through its data directory is one of its readers.
+
+LRPS2 reads pcsx2/resources/GameIndex.yaml from the tree its data directory
+reference names and declares no file entry for it. The truth entry other
+cores build for that path named armsx2 and yaps2 alone, so the export paired
+RetroArch's System.dat line, which describes LRPS2's copy, with armsx2's
+revision, and hash_conflict did not see LRPS2's value.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import os
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+sys.path.insert(0, str(REPO_ROOT / "scripts" / "exporter"))
+
+from exporter.baseline import checked_hashes  # noqa: E402
+from truth import generate_platform_truth  # noqa: E402
+
+GAME_INDEX = "pcsx2/resources/GameIndex.yaml"
+DECLARED = b"the revision armsx2 declares"
+TREE_COPY = b"the revision the tree holds"
+
+
+def _profile(name: str, **fields) -> dict:
+    return {"emulator": name, "type": "libretro", "systems": ["sony-playstation-2"], **fields}
+
+
+class DataDirectoryReaders(unittest.TestCase):
+    def setUp(self):
+        self._tmp = tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp")
+        self.addCleanup(self._tmp.cleanup)
+        root = Path(self._tmp.name)
+        for tree, content in (("lrps2", TREE_COPY), ("resources", TREE_COPY)):
+            relative = GAME_INDEX if tree == "lrps2" else "GameIndex.yaml"
+            copy = root / tree / relative
+            copy.parent.mkdir(parents=True)
+            copy.write_bytes(content)
+        self.registry = {
+            "lrps2": {"local_cache": str(root / "lrps2")},
+            "resources": {"local_cache": str(root / "resources")},
+        }
+        self.profiles = {
+            "armsx2": _profile("armsx2", files=[{
+                "name": "GameIndex.yaml", "path": GAME_INDEX, "system": "sony-playstation-2",
+                "sha1": hashlib.sha1(DECLARED).hexdigest(),
+            }]),
+            "lrps2": _profile("lrps2", data_directories=[
+                {"ref": "lrps2", "destination": ""},
+            ], files=[{"name": "<bios>.bin", "path": "pcsx2/bios/<bios>.bin"}]),
+            # Names what it reads in the tree, patches.zip alone: the tree
+            # adds no reader of GameIndex.yaml (pcee2 compiles it in).
+            "listed": _profile("listed", data_directories=[
+                {"ref": "resources", "destination": "pcsx2/resources"},
+            ], files=[{"name": "patches.zip", "path": "pcsx2/resources/patches.zip"}]),
+        }
+        self.config = {"cores": ["armsx2", "lrps2", "listed"],
+                       "systems": {"sony-playstation-2": {"files": []}}}
+
+    def _entry(self, registry: dict) -> dict:
+        model = generate_platform_truth(
+            "plat", self.config, {}, self.profiles, data_registry=registry,
+        )
+        return next(
+            f for f in model["systems"]["sony-playstation-2"]["files"]
+            if f["name"] == "GameIndex.yaml"
+        )
+
+    def test_the_reader_counts_and_its_copy_conflicts(self):
+        entry = self._entry(self.registry)
+        self.assertEqual(entry["_cores"], ["armsx2", "lrps2"])
+        self.assertIn("sha1", entry["hash_conflict"])
+        # The kept value describes one revision among those the cores read:
+        # it pairs a line, it never corrects one.
+        self.assertNotIn("sha1", checked_hashes(entry))
+
+    def test_without_the_cache_nothing_is_folded(self):
+        entry = self._entry({})
+        self.assertEqual(entry["_cores"], ["armsx2"])
+        self.assertNotIn("hash_conflict", entry)
+
+    def test_the_same_copy_adds_a_reader_and_no_conflict(self):
+        tree_copy = Path(self.registry["lrps2"]["local_cache"]) / GAME_INDEX
+        tree_copy.write_bytes(DECLARED)
+        entry = self._entry(self.registry)
+        self.assertEqual(entry["_cores"], ["armsx2", "lrps2"])
+        self.assertNotIn("hash_conflict", entry)
+
+
+if __name__ == "__main__":
+    os.environ.setdefault("RETROBIOS_OFFLINE", "1")
+    unittest.main()