fix: say which folder the folder screen offers

install.py

@@ -10304,6 +10304,11 @@ class TuiState:
         # A --dest given without --platform: the list asks whose files go there.
         self.dest_given: Path | None = None
         self.folder_default: Path | None = None
+        # What folder_default is, for the words above it: "usual" (the
+        # platform's built-in folder), "found" (the one detected here),
+        # "chosen" (the run's folder, from Change folder) or "closed" (the
+        # one chosen could not be opened, none is offered).
+        self.folder_kind: str = "usual"
         self.path_text: str = ""
         self.browse_dir: Path | None = None
         self.browse_rows: list = []
@@ -10954,7 +10959,7 @@ def _choose(state: TuiState, plat: str, dest: Path) -> list[tuple]:
         # The folder found here is the one the frontend reads: the built-in
         # default beside it is one it does not, offered as "reads its BIOS
         # files from" and filled with Enter.
-        state.folder_default = None
+        state.folder_default, state.folder_kind = None, "closed"
         return _push(state, "folder")
     card = card_system(dest)
     if card and card[0] == plat and card[1] != dest:
@@ -10979,9 +10984,14 @@ def _choose(state: TuiState, plat: str, dest: Path) -> list[tuple]:
     return _start_check(state)
 
 
-def _open_folder_screen(state: TuiState, default: Path | None) -> list[tuple]:
-    state.folder_default = default
-    return _push(state, "folder")
+def _open_folder_screen(state: TuiState, default: Path | None,
+                        kind: str = "usual") -> list[tuple]:
+    state.folder_default, state.folder_kind = default, kind
+    refused = kind == "chosen" and (state.facts.get("writable") is False
+                                    or _short_of_space(state, state.check or {}))
+    # A folder just refused as full or read-only: Browse, not Use this
+    # folder, is under A, or A, A came back to the same warning.
+    return _push(state, "folder", 1 if refused and default is not None else 0)
 
 
 def _mount_name(mount: Path) -> str:
@@ -11115,8 +11125,15 @@ def _activate(state: TuiState, row: TuiRow) -> list[tuple]:
         if state.dest_given is not None:
             return _choose(state, row.value, state.dest_given)
         state.platform = row.value
-        default = None if row.value in CARD_PLATFORMS else _default_dest(state.os_type, row.value)
-        return _open_folder_screen(state, default)
+        if row.value in CARD_PLATFORMS:
+            return _open_folder_screen(state, None)
+        # The folder detected here before the built-in one: the built-in
+        # default was offered as where RetroArch reads, when the
+        # retroarch.cfg found here names another.
+        found = next((path for plat, path, _label in state.setups if plat == row.value), None)
+        if found is not None:
+            return _open_folder_screen(state, found, "found")
+        return _open_folder_screen(state, _default_dest(state.os_type, row.value))
     if screen == "folder":
         if action == "default":
             return _choose(state, state.platform, state.folder_default)
@@ -11165,7 +11182,7 @@ def _activate(state: TuiState, row: TuiRow) -> list[tuple]:
         if action == "quit":
             return tui_quit(state)
         if action == "folder":
-            return _open_folder_screen(state, state.dest)
+            return _open_folder_screen(state, state.dest, "chosen")
         if action == "fromcard":
             return _open_from_browser(state)
         if action in ("misplaced", "unreadable"):
@@ -11236,7 +11253,7 @@ def _option(state: TuiState, action: str, step: int) -> list[tuple]:
     elif action in ("regions", "command"):
         return _push(state, action)
     elif action == "folder":
-        return _open_folder_screen(state, state.dest)
+        return _open_folder_screen(state, state.dest, "chosen")
     elif action == "from" and step < 0:
         # Said, and the screen stays: Back to the plan counts again.
         if state.from_folders:
@@ -12052,7 +12069,13 @@ def _view_folder(state: TuiState, width: int, height: int) -> tuple:
                   "root folder, the one holding .system."]
     elif state.folder_default is not None:
         title = "Which folder?"
-        before = [f"{name} usually reads its BIOS files from:", str(state.folder_default)]
+        lead = {"found": f"{name} reads its BIOS files from:",
+                "chosen": f"The BIOS folder chosen for {name}:"}.get(
+                    state.folder_kind, f"{name} usually reads its BIOS files from:")
+        before = [lead, str(state.folder_default)]
+    elif state.folder_kind == "closed":
+        title = "Which folder?"
+        before = [f"Choose another folder for {name}: browse for it or type it."]
     else:
         title = "Which folder?"
         before = [f"No usual {name} folder here: browse for it or type it."]

tests/test_install_tui.py

@@ -3783,5 +3783,65 @@ class EndToEnd(unittest.TestCase):
         self.assertNotIn(b"\x1b", term.raw)
 
 
+class TheFolderScreenSaysWhatItOffers(unittest.TestCase):
+    """The folder screen said "usually reads its BIOS files from" for any
+    folder it offered: the folder named with --dest, reached by Change
+    folder, and the built-in default while the retroarch.cfg found here
+    names another. A closed folder found here opened on "No usual
+    RetroArch folder here" under the setup that listed it."""
+
+    def said(self, state: install.TuiState) -> str:
+        return " ".join(" ".join(install.tui_view(state, 200, 40)).split())
+
+    def test_change_folder_names_the_chosen_folder(self):
+        state = checked_state()
+        state.stack = ["setup", "plan"]
+        mine = Path("/home/user/typed/mybios")
+        state.dest = mine
+        install._activate(state, install.TuiRow("folder", "Change folder"))
+        self.assertEqual(state.screen, "folder")
+        screen = self.said(state)
+        self.assertNotIn("usually reads", screen)
+        self.assertIn(f"The BIOS folder chosen for RetroArch: {mine}", screen)
+
+    def test_another_setup_offers_the_folder_found_here(self):
+        state = fresh_state()
+        found = Path("/home/user/Games/bios")
+        state.setups = [("retroarch", found, "RetroArch")]
+        state.stack = ["setup", "platforms"]
+        install._activate(state, install.TuiRow("platform", "RetroArch", value="retroarch"))
+        self.assertEqual(state.folder_default, found)
+        self.assertIn(f"RetroArch reads its BIOS files from: {found}", self.said(state))
+
+    def test_with_none_found_the_usual_folder_is_offered(self):
+        state = fresh_state()
+        state.setups = []
+        state.stack = ["setup", "platforms"]
+        install._activate(state, install.TuiRow("platform", "RetroArch", value="retroarch"))
+        self.assertIn("RetroArch usually reads its BIOS files from:", self.said(state))
+
+    def test_a_closed_folder_found_here_asks_for_another(self):
+        state = fresh_state()
+        state.stack = ["setup"]
+        with mock.patch.object(install, "closed_folder",
+                               return_value=(Path("/home/user/lock"), "Permission denied")):
+            install.tui_update(state, Key("enter"))
+        self.assertEqual(state.screen, "folder")
+        screen = self.said(state)
+        self.assertNotIn("No usual RetroArch folder here", screen)
+        self.assertIn("Choose another folder for RetroArch", screen)
+
+    def test_a_refused_folder_puts_browse_under_a(self):
+        for facts in ({"free": 10, "writable": True, "cores": []},
+                      {"free": 50 * 1024 ** 3, "writable": False, "cores": []}):
+            with self.subTest(facts=facts):
+                state = checked_state(facts)
+                self.assertEqual(install.tui_rows(state)[0].action, "folder")
+                install.tui_update(state, Key("enter"))
+                self.assertEqual(state.screen, "folder")
+                rows = install.tui_rows(state)
+                self.assertEqual(rows[state.focus["folder"]].action, "browse")
+
+
 if __name__ == "__main__":
     unittest.main()