fix: let search order guard regional files

tests/test_install_selection.py

@@ -64,16 +64,21 @@ class TheRegionRuleIsTheBuilders(unittest.TestCase):
                         if rng.random() < 0.2
                         else set(rng.sample(self.POOL, rng.randint(1, 2)))
                     )
+                    priority = rng.choice([None, None, 5, 10, 100, 200])
                     entries[dest] = {"dest": dest, "regions": sorted(regions),
                                      "region_groups": []}
+                    if priority is not None:
+                        entries[dest]["priority"] = priority
                     index[dest] = {"regions": regions,
-                                   "has_untagged": not regions, "emulators": []}
+                                   "has_untagged": not regions, "emulators": [],
+                                   "priorities": {priority}}
                 groups.setdefault(f"g{g}", []).append((dest, dest))
                 if f"g{g}" not in entries[dest]["region_groups"]:
                     entries[dest]["region_groups"].append(f"g{g}")
         for entry in entries.values():
             if not entry["regions"]:
                 del entry["regions"], entry["region_groups"]
+                entry.pop("priority", None)
         requested = rng.sample(["north-america", "europe", "japan", "uk", "canada"],
                                rng.randint(1, 3))
         return groups, index, list(entries.values()), requested

tests/test_region.py

@@ -265,6 +265,25 @@ class TestResolveRegionDrops(unittest.TestCase):
     def _drops(self, groups, requested):
         return region.resolve_region_drops(groups, self.index, requested)
 
+    def test_a_world_file_the_code_ranks_lower_keeps_the_regional_ones(self):
+        """DuckStation looks for its PS1 images (5) before the world PS2 ones
+        (100): asked for Brazil, it kept only the PS2 fallbacks."""
+        index = region.build_region_index({"duckstation": {"files": [
+            {"name": "scph5501.bin", "region": ["north-america"], "priority": 5},
+            {"name": "ps2_scph30001.bin", "region": ["north-america"], "priority": 150},
+            {"name": "ps2_scph10000.bin", "region": ["world"], "priority": 100},
+        ]}})
+        groups = {"psx": [(n, n) for n in ("scph5501.bin", "ps2_scph30001.bin",
+                                            "ps2_scph10000.bin")]}
+        self.assertEqual(
+            region.resolve_region_drops(groups, index, ["brazil"]), {"ps2_scph30001.bin"}
+        )
+
+    def test_without_ranks_the_world_file_still_wins(self):
+        groups = {"psx": [("scph5501.bin", "scph5501.bin"),
+                          ("psxonpsp660.bin", "psxonpsp660.bin")]}
+        self.assertEqual(self._drops(groups, ["brazil"]), {"scph5501.bin"})
+
     def test_best_rank_wins_and_siblings_drop(self):
         groups = {
             "psx": [
@@ -677,6 +696,8 @@ class RegionalRequestsKeepWhatTheCodeLoads(unittest.TestCase):
         ("ace-dl", ["denmark"], "private/firmware/XMEM_FW_3_15_UK.rom"),
         ("ace-dl", ["spain"], "private/hacker/hacker481fr.rom"),
         ("ace-dl", ["france"], "private/firmware/Amstrad_s4.cpr"),
+        ("duckstation", ["brazil"], "scph5501.bin"),
+        ("duckstation", ["south-korea"], "scph5500.bin"),
     )
 
     def test_each_request_keeps_its_file(self):