Report Python startup errors in flet test; bump Flutter to 3.47.8

.fvmrc

@@ -1,3 +1,3 @@
 {
-  "flutter": "3.47.7"
+  "flutter": "3.47.8"
 }

CHANGELOG.md

@@ -45,7 +45,7 @@
 * Add `Theme.markdown_theme`: a default `MarkdownStyleSheet` for every `Markdown`, with a control's own `md_style_sheet` applied on top property by property by @FeodorFitsner.
 * Add `PopupMenuTheme.border_radius` to set the default hover/splash corner radius of every `PopupMenuButton` by @FeodorFitsner.
 
-* Bump the bundled Flutter to [3.47.7](https://github.com/flutter/flutter/blob/stable/CHANGELOG.md#3477) (from 3.44.8). Android builds use Gradle 9.3.1, Android Gradle Plugin 8.13.2 and Kotlin 2.3.21 by @ndonkoHenri.
+* Bump the bundled Flutter to [3.47.8](https://github.com/flutter/flutter/blob/stable/CHANGELOG.md#3478) (from 3.44.8). Android builds use Gradle 9.3.1, Android Gradle Plugin 8.13.2 and Kotlin 2.3.21 ([#6916](https://github.com/flet-dev/flet/pull/6916), [#7023](https://github.com/flet-dev/flet/pull/7023)) by @ndonkoHenri.
 
   **Compatibility:** Desktop apps and the desktop app that `flet run` opens now render with Impeller, Flutter 3.47's default desktop renderer, instead of Skia. Use `flet build --no-impeller` (or `impeller = false` under `[tool.flet]`), `flet run --no-impeller` or the `FLET_NO_IMPELLER` environment variable to render with Skia; see [Renderer](/docs/publish#renderer). Android plugins that still use `jcenter()` or other APIs removed in Gradle 9 no longer build. `flet build` downloads Flutter 3.47.7 on first use.
 
@@ -59,14 +59,14 @@
 
 ### Bug fixes
 
-* Fix `use_state()` type inference for callable initializers in mypy and ty ([#6960](https://github.com/flet-dev/flet/issues/6960), [#7014](https://github.com/flet-dev/flet/pull/7014)) by @mmporong.
+* Fix `use_state()` and `use_ref()` type inference for callable initializers in mypy and ty ([#6960](https://github.com/flet-dev/flet/issues/6960), [#7014](https://github.com/flet-dev/flet/pull/7014), [#7023](https://github.com/flet-dev/flet/pull/7023)) by @mmporong.
 * Fix `flet build` apps showing a blank page when the system suspended them while Python was starting, such as when iOS launches an app in the background for a notification action ([#6999](https://github.com/flet-dev/flet/pull/6999)) by @ndonkoHenri.
 * Fix `flet build` naming a Linux app's icons `None.png` and leaving the iOS frameworks it builds from the app's packages under shared identifiers when no `bundle_id` is set ([#6999](https://github.com/flet-dev/flet/pull/6999)) by @ndonkoHenri.
 * Fix `flet build` writing numbers in `[tool.flet.macos.entitlement]`, `[tool.flet.ios.info]` and `[tool.flet.macos.info]` as strings, producing invalid plists when keys or values contain `&` or `<`, and failing when a `pyproject.toml` value contains `{{` ([#6999](https://github.com/flet-dev/flet/pull/6999)) by @ndonkoHenri.
 * Fix `FilePicker` dialogs failing with a timeout after being open for an hour ([#6999](https://github.com/flet-dev/flet/pull/6999)) by @ndonkoHenri.
 * Fix `flet build` failing on every rebuild after one with changed build options, in apps with Flutter extensions ([#7010](https://github.com/flet-dev/flet/issues/7010), [#7012](https://github.com/flet-dev/flet/pull/7012)) by @ndonkoHenri.
 * Fix `flet build` not reinstalling the app's packages after `requirements.txt` is edited or `build/site-packages` is deleted ([#6994](https://github.com/flet-dev/flet/issues/6994), [#6996](https://github.com/flet-dev/flet/pull/6996)) by @ndonkoHenri.
-* Fix `flet test` failing when the app under test starts slowly, as on the first run after a build: the test now waits until the app finishes initializing its first page ([#6993](https://github.com/flet-dev/flet/issues/6993), [#6995](https://github.com/flet-dev/flet/pull/6995)) by @ndonkoHenri.
+* Fix `flet test` failing when the app under test starts slowly, as on the first run after a build: the test now waits until the app finishes initializing its first page, and fails right away with the Python traceback when the app's Python program fails to start ([#6993](https://github.com/flet-dev/flet/issues/6993), [#6995](https://github.com/flet-dev/flet/pull/6995), [#7023](https://github.com/flet-dev/flet/pull/7023)) by @ndonkoHenri.
 * Fix `use_effect()` cleanups being skipped: a cleanup returned by the setup was lost once the component re-rendered, only one ran when `cleanup=` was passed too, and `async` cleanups never ran when a dependency change re-ran the effect. A pending `async` setup is also cancelled on unmount ([#6963](https://github.com/flet-dev/flet/issues/6963), [#6983](https://github.com/flet-dev/flet/pull/6983), [#7005](https://github.com/flet-dev/flet/pull/7005)) by @mangod12.
 * iOS apps built with `flet build ipa` no longer fail App Store Connect validation with ITMS-90683 (missing `NSPhotoLibraryUsageDescription` and `NSCameraUsageDescription` purpose strings): the `file_picker` plugin is updated to 13.x, which picks photos with the system photo picker and no longer links DKImagePickerController's camera and photo-library code. `device_info_plus`, `package_info_plus` and `share_plus` move to their next major versions with it (`win32` 6). `FilePicker.save_file()` on desktop now creates the chosen file (empty when no `src_bytes` are given) before returning its path by @FeodorFitsner.
 * Fix `Tester.find_by_key()` not finding `Tab` and `PopupMenuItem` controls by their keys ([#6965](https://github.com/flet-dev/flet/issues/6965), [#6976](https://github.com/flet-dev/flet/pull/6976)) by @RezaShamsipour.

packages/flet/CHANGELOG.md

@@ -1,5 +1,6 @@
 ## 1.1.0
 
+* Flutter updated to [3.47.8](https://github.com/flutter/flutter/blob/stable/CHANGELOG.md#3478).
 * Update `file_picker` to 13.x (federated; iOS picks media with `PHPickerViewController`, dropping DKImagePickerController, whose camera and photo-library references made App Store Connect demand purpose strings). `FilePickerService` uses `pickFile()`/`pickFiles()`, reads bytes and uploads through `PlatformFile.readAsBytes()`/`readAsByteStream()`, passes `lockParentWindow` through `WindowsOptions`/`LinuxOptions` and `cancel_upload_on_window_blur` through `file_picker_web`'s `FilePickerWebOptions` (imported only on web). `saveFile()` always writes the file, so desktop saves without `src_bytes` create it empty. Bump `device_info_plus` to ^13.3.0, `package_info_plus` to ^10.2.2 and `share_plus` to ^13.3.1 (`win32` 6, required by file_picker 13's Windows implementation) by @FeodorFitsner.
 * Apply `min_width`/`max_width`/`min_height`/`max_height` to every `LayoutControl` as a `ConstrainedBox` around the control (outside any fixed size). A control that implements one of these names itself lists it in `skip_properties` (`ListTile.min_height`, `NavigationRail.min_width`) by @FeodorFitsner.
 * Pass `material_tap_target_size` to `Switch` and `ThemeData` (`parseMaterialTapTargetSize()`) by @FeodorFitsner.
@@ -22,7 +23,6 @@
 * An embedded page builds its `Navigator` with `requestFocus: false`, so pushing its routes doesn't move the focus out of the host app by @FeodorFitsner.
 * `PageControl` wraps an embedded page's app in a `CupertinoTheme` derived from the page's own Material theme (top-level pages are unchanged). Flutter's `Theme` reuses an ambient `CupertinoTheme` when one exists above it instead of deriving one from its `ThemeData`, so an embedded page's Cupertino widgets took the host app's colors by @FeodorFitsner.
 * `CupertinoButtonControl` falls back to the `ButtonStyle` in `internals["style"]` - what an adaptive Material `Button` sends - for background, foreground and padding when `bgcolor`/`color`/`padding` are absent by @FeodorFitsner.
-* Flutter updated to [3.47.7](https://github.com/flutter/flutter/blob/stable/CHANGELOG.md#3477).
 * **Breaking:** `parseTheme()` now builds themes from a seed with neutral surfaces by default (`#ffffff` / `#121212` and a neutral grey ramp for surface containers, `onSurface`, `outline` and inverse surfaces); the seed still drives accent colors. A theme's `surfaces: "tonal"` restores the seed-tinted Material 3 surfaces. Adds the `ThemeSurfaces` enum, `parseThemeSurfaces()` and `neutralizeSurfaces()` ([#6921](https://github.com/flet-dev/flet/issues/6921)) by @FeodorFitsner.
 * Import Material and Cupertino from the `material_ui` and `cupertino_ui` packages instead of `package:flutter/material.dart` and `package:flutter/cupertino.dart`. Helpers that take or return Material or Cupertino types, such as `parseColor()`, `parseTextStyle()` and `parseButtonStyle()`, now use those packages' types, and `flet.dart` no longer re-exports `Icons` and `CupertinoIcons`. Requires Flutter 3.47 or later.
 * Add `markdownStyleSheetFromTheme()`, which builds the default `MarkdownStyleSheet` from a `material_ui` theme. `MarkdownStyleSheet.fromTheme()` from `flutter_markdown_plus` only accepts the Flutter SDK's `ThemeData`.

packages/flet_integration_test/lib/src/app_startup.dart

@@ -9,12 +9,22 @@ import 'package:flutter_test/flutter_test.dart';
 /// the first launch after a build, when antivirus software scans the bundle,
 /// so a fixed number of frames is not enough. Throws when the app reports a
 /// startup error or has not loaded within [timeout].
+///
+/// A startup error includes the embedded Python program failing before it
+/// connects, such as an exception raised while importing the app's modules.
+/// The app reports that on its boot screen rather than through the Flet
+/// protocol, so the thrown exception carries the boot screen's error text,
+/// including the Python traceback.
 Future<void> waitForAppLoaded(WidgetTester tester,
     {Duration timeout = const Duration(minutes: 2)}) async {
   final deadline = tester.binding.clock.now().add(timeout);
   while (true) {
     await tester.pump(const Duration(milliseconds: 100));
     final backend = _findFletBackend(tester);
+    final bootError = backend?.bootStatus.value.error;
+    if (bootError != null && bootError.isNotEmpty) {
+      throw Exception("The app failed to start:\n$bootError");
+    }
     if (backend != null && !backend.isLoading) {
       if (backend.error.isNotEmpty) {
         throw Exception("The app failed to start: ${backend.error}");

packages/flet_integration_test/test/app_startup_test.dart

@@ -74,6 +74,22 @@ void main() {
             contains('Initialization failed'))));
   });
 
+  testWidgets('a Python program that fails to start fails with its traceback',
+      (tester) async {
+    final backend = await _mountApp(tester);
+    // The embedded Python program exits before it connects, so the backend
+    // is still loading and only the boot screen shows the error.
+    Timer(const Duration(milliseconds: 300), () {
+      backend.bootStatus.value = const BootStatus(BootStage.startingUp,
+          error: "ModuleNotFoundError: No module named 'pydantic_core'");
+    });
+
+    await expectLater(
+        () => waitForAppLoaded(tester),
+        throwsA(isA<Exception>().having((e) => e.toString(), 'message',
+            contains("No module named 'pydantic_core'"))));
+  });
+
   testWidgets('a registered app that never initializes times out',
       (tester) async {
     final backend = await _mountApp(tester);

sdk/python/packages/flet/src/flet/components/hooks/use_ref.py

@@ -2,7 +2,7 @@
 
 from collections.abc import Callable
 from dataclasses import dataclass
-from typing import Generic, TypeVar
+from typing import Any, Generic, TypeVar, overload
 
 from flet.components.hooks.hook import Hook
 from flet.components.utils import current_component
@@ -35,6 +35,20 @@ class RefHook(Hook, Generic[RefValueT]):
     ref: MutableRef[RefValueT]
 
 
+@overload
+def use_ref(initial_value: None = None) -> MutableRef[Any]: ...
+
+
+@overload
+def use_ref(initial_value: Callable[[], RefValueT]) -> MutableRef[RefValueT]: ...
+
+
+@overload
+def use_ref(
+    initial_value: RefValueT | Callable[[], RefValueT],
+) -> MutableRef[RefValueT]: ...
+
+
 def use_ref(
     initial_value: RefValueT | Callable[[], RefValueT] | None = None,
 ) -> MutableRef[RefValueT]: