feat: name each system once, from its own section

siterender.system_name reads the heading of the console section the id spells, then SYSTEM_NAMES, and raises for an id in neither. The emulator intro and the picker titles read it instead of the folder a system's files were voted onto.

tests/test_site_r2_p0.py

@@ -0,0 +1,120 @@
+"""One display name per system id (round 2, package P0).
+
+An emulator page listed the folders a system's files were voted onto:
+nintendo-gba read "Nintendo Game Boy", camplynx "Arcade", and MAME
+"emulated FBNeo". siterender.system_name names a system from the console
+section that is its own, then from SYSTEM_NAMES, and raises otherwise.
+database.json carries no system id: its files reach a page through their
+console folders, so the ids to name are the platforms' and the profiles'.
+"""
+
+from __future__ import annotations
+
+import json
+import sys
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+import siterender  # noqa: E402
+from common import (  # noqa: E402
+    list_registered_platforms,
+    load_emulator_profiles,
+    load_platform_config,
+)
+from generate_site import _group_by_manufacturer  # noqa: E402
+
+
+def _profile_system_ids(profiles: dict[str, dict]) -> set[str]:
+    ids: set[str] = set()
+    for profile in profiles.values():
+        ids.update(str(sys_id) for sys_id in profile.get("systems") or [])
+        for entry in profile.get("files") or []:
+            if not isinstance(entry, dict):
+                continue
+            if entry.get("system"):
+                ids.add(str(entry["system"]))
+            ids.update(str(sys_id) for sys_id in entry.get("systems") or [])
+    return ids
+
+
+class SystemNames(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls) -> None:
+        with open(REPO_ROOT / "database.json", encoding="utf-8") as handle:
+            db = json.load(handle)
+        cls.manufacturers = _group_by_manufacturer(db)
+        cls.profiles = load_emulator_profiles(
+            str(REPO_ROOT / "emulators"), skip_aliases=False)
+        siterender.set_console_sections(
+            cls.manufacturers, siterender.program_names(cls.profiles))
+        platforms_dir = str(REPO_ROOT / "platforms")
+        cls.platform_ids = {
+            sys_id
+            for name in list_registered_platforms(platforms_dir, include_archived=True)
+            for sys_id in load_platform_config(name, platforms_dir).get("systems", {})
+        }
+        cls.profile_ids = _profile_system_ids(cls.profiles)
+
+    def _all_ids(self) -> set[str]:
+        return self.platform_ids | self.profile_ids
+
+    def test_every_system_id_has_a_name(self) -> None:
+        unnamed = []
+        for sys_id in sorted(self._all_ids()):
+            try:
+                name = siterender.system_name(sys_id)
+            except KeyError:
+                unnamed.append(sys_id)
+                continue
+            self.assertTrue(name.strip(), sys_id)
+        self.assertEqual(unnamed, [], "add these to siterender.SYSTEM_NAMES")
+
+    def test_no_name_is_a_manufacturer_page_or_an_emulator(self) -> None:
+        taken = {name.casefold() for name in self.manufacturers}
+        taken |= {name.casefold() for name in siterender.program_names(self.profiles)}
+        clashes = sorted(
+            (sys_id, siterender.system_name(sys_id))
+            for sys_id in self._all_ids()
+            if siterender.system_name(sys_id).casefold() in taken
+        )
+        self.assertEqual(clashes, [])
+
+    def test_table_entries_are_reached(self) -> None:
+        """A table entry an own section shadows is never read, and an entry
+        no platform or profile names is a leftover."""
+        shadowed = sorted(
+            sys_id for sys_id in siterender.SYSTEM_NAMES
+            if siterender._own_section(sys_id) is not None
+        )
+        self.assertEqual(shadowed, [])
+        unused = sorted(set(siterender.SYSTEM_NAMES) - self._all_ids())
+        self.assertEqual(unused, [])
+
+    def test_names_that_read_a_folder_vote(self) -> None:
+        self.assertEqual(siterender.system_name("nintendo-gba"), "Nintendo Game Boy Advance")
+        self.assertEqual(siterender.system_name("camplynx"), "Camputers Lynx")
+        self.assertEqual(siterender.system_name("atari-lynx"), "Atari Lynx")
+        self.assertEqual(siterender.system_name("arcade"), "Arcade games")
+        self.assertEqual(siterender.system_name("sega-naomi"), "Sega NAOMI")
+
+    def test_own_section_names_from_its_heading(self) -> None:
+        self.assertEqual(siterender.system_name("nintendo-snes"), "Nintendo SNES")
+        self.assertEqual(siterender.system_name("sony-playstation"), "Sony PlayStation")
+
+    def test_an_unknown_id_raises(self) -> None:
+        with self.assertRaises(KeyError):
+            siterender.system_name("no-such-system-anywhere")
+
+    def test_mame_names_systems_not_emulators(self) -> None:
+        names = {siterender.system_name(s) for s in self.profiles["mame"].get("systems") or []}
+        self.assertNotIn("FBNeo", names)
+        self.assertNotIn("Arcade", names)
+        self.assertFalse(names & siterender.program_names(self.profiles))
+
+
+if __name__ == "__main__":
+    unittest.main()