fix: offer a drive by the folder its system reads

RetroArch's folder question numbered a Batocera SHARE drive and filled
its root. A drive is now offered by its own system's BIOS folder, one
nothing names by its bios folder, and another system's is left out and
named with the options that reach it. A list or pack card setups read
too opens on those setups, in both modes.

tests/test_install_tui.py

@@ -6704,6 +6704,86 @@ class LineModeAndScreenDecideAlike(unittest.TestCase):
                     self.assertIn("a run without questions installs for one", text)
                     self.assertRegex(text, r"--platform \w+ --dest ")
 
+    def share(self, name: str = "SHARE") -> Path:
+        share = self.root / "media" / name
+        (share / "system").mkdir(parents=True)
+        (share / "roms").mkdir()
+        (share / "system" / "batocera.conf").write_text("system.hostname=BATOCERA\n")
+        return share
+
+    def test_a_drive_is_offered_by_the_folder_its_system_reads(self):
+        """code_audit_18 P2-2, tui_audit_11 P1-2: RetroArch's folder question
+        numbered a Batocera SHARE drive and a KNULLI card, and one press put
+        RetroArch's list at their root, beside roms/ and system/. A drive
+        nothing names went to its root too. Now another system's drive is
+        left out and said, in both modes, and a drive is its bios folder."""
+        share, knulli = self.share(), self.card("KNULLI", "KNULLI")
+        stick = self.root / "media" / "EASYROMS"
+        (stick / "bios").mkdir(parents=True)
+        onion = self.card("ONION", "Onion")
+        mounts = [share, knulli, stick, onion]
+        with mock.patch.object(install, "_mounted_cards", return_value=mounts), \
+                mock.patch.object(install, "_mount_points", return_value=frozenset()), \
+                contextlib.redirect_stdout(io.StringIO()) as out, \
+                mock.patch.object(install, "_ask", side_effect=["q"]), \
+                self.assertRaises(SystemExit):
+            install.ask_platform_folder("linux", "retroarch")
+        text = out.getvalue()
+        self.assertIn(f"1) EASYROMS: bios (card or drive) ({stick / 'bios'})", text)
+        self.assertIn(f"2) ONION: BIOS (Onion SD card) ({onion / 'BIOS'})", text)
+        self.assertNotIn("3)", text)
+        self.assertIn("Not offered here, each reads its own system's files: SHARE (Batocera "
+                      f"SHARE drive: --platform batocera --dest {share}), KNULLI (KNULLI SD "
+                      f"card: --platform knulli --dest {knulli}).", text)
+        state = install.TuiState(os_type="linux", home=HOME)
+        state.platform, state.stack = "retroarch", ["folder"]
+        state.folder_default, state.folder_kind = SYSTEM_DIR, "usual"
+        with mock.patch.object(install, "_mounted_cards", return_value=mounts), \
+                mock.patch.object(install, "_mount_points", return_value=frozenset()):
+            rows = install.tui_rows(state)
+            screen = " ".join(install.tui_view(state, 120, 40))
+            state.focus["folder"] = next(index for index, row in enumerate(rows)
+                                         if row.action == "drive")
+            install.tui_update(state, Key("enter"))
+        self.assertEqual([row.value for row in rows if row.action == "drive"],
+                         [stick / "bios", onion / "BIOS"])
+        self.assertIn("Not offered here", screen)
+        self.assertEqual(state.dest, stick / "bios")
+
+    def test_a_list_card_setups_read_offers_them_first(self):
+        """tui_audit_11 P1-2: with a RetroArch pack or list and nothing found,
+        the first screen was RetroArch's folder question: ArkOS, muOS and
+        JELOS, which read the same list, were out of reach. Both modes now
+        open on the setups that read it, RetroArch first."""
+        stick = self.root / "media" / "EASYROMS"
+        (stick / "bios").mkdir(parents=True)
+        args = dict(manifest=self.list, declared_only=False, offline=False)
+        text, asked = self.line_run(_args(**args), [], mounts=[stick])
+        self.assertIn("Which setup is the RetroArch list for?", text)
+        self.assertIn("ArkOS", text)
+        self.assertNotIn("Batocera", text)
+        self.assertIn("[Enter for RetroArch]", asked[0])
+        with mock.patch.object(install, "_mounted_cards", return_value=[stick]), \
+                mock.patch.object(install, "_mount_points", return_value=frozenset()), \
+                mock.patch.object(install, "detect_platforms", return_value=[]), \
+                mock.patch.object(install, "detect_frontends", return_value=[]):
+            install._DETECTED_OS.clear()
+            state = screen_keys(_args(**args), [])
+            with contextlib.redirect_stdout(io.StringIO()):
+                install._open_local_sources(_args(**args))
+            rows = install.tui_rows(state)
+            labels = [row.label for row in rows]
+            focused = rows[state.focus["platforms"]]
+            install._DETECTED_OS.clear()
+            ark = screen_keys(_args(**args), ["end", Key("char", "/"), *[
+                Key("char", c) for c in "arkos"], "enter", "enter"])
+        self.assertEqual(state.screen, "platforms")
+        self.assertEqual(focused.value, "retroarch")
+        self.assertTrue(any(label.startswith("ArkOS") for label in labels), labels)
+        self.assertFalse(any(label.startswith("Batocera") for label in labels), labels)
+        self.assertEqual(ark.screen, "folder")
+        self.assertEqual(install._tui_card_bound(ark)[0], "ArkOS")
+
     def test_line_mode_says_the_card_it_found_and_names_its_folder(self):
         onion = self.card("ONION", "Onion")
         with mock.patch.object(install, "_mounted_cards", return_value=[onion]), \
@@ -6741,7 +6821,8 @@ class LineModeAndScreenDecideAlike(unittest.TestCase):
                 mock.patch.object(install, "detect_os", return_value="linux"), \
                 mock.patch.object(install.sys.stdin, "isatty", return_value=True), \
                 mock.patch.object(install, "_is_terminal", return_value=True), \
-                mock.patch.object(install, "_ask", return_value=str(self.here)), \
+                mock.patch.object(install, "_ask", side_effect=lambda prompt: (
+                    "" if prompt.startswith(">") else str(self.here))), \
                 mock.patch.object(install, "_prompt_custom_selection", menu), \
                 contextlib.redirect_stdout(io.StringIO()) as out, \
                 self.assertRaises(SystemExit):
@@ -7089,13 +7170,16 @@ class LineModeAndScreenDecideAlike(unittest.TestCase):
                 mock.patch.object(install, "_ask", side_effect=["1"]), \
                 mock.patch.object(install, "_missing_dest", return_value=True):
             folder = install.ask_platform_folder("linux", "retroarch")
-        self.assertEqual(folder, stick)
+        # tui_audit_11 P1-2: a drive is offered by its bios folder, never its
+        # root, which no setup reads.
+        self.assertEqual(folder, stick / "bios")
         state = install.TuiState(os_type="linux", home=HOME)
         state.platform, state.stack = "retroarch", ["folder"]
         state.folder_default, state.folder_kind = SYSTEM_DIR, "usual"
         with mock.patch.object(install, "_mounted_cards", return_value=mounts):
             rows = install.tui_rows(state)
-        self.assertEqual([row.value for row in rows if row.action == "drive"], [stick])
+        self.assertEqual([row.value for row in rows if row.action == "drive"],
+                         [stick / "bios"])
 
     def test_the_systems_are_listed_by_title_in_the_screen_order(self):
         """tui_audit_10 P3-7: line mode listed ids, nintendo-3ds before