Report voice recording failures via onRecordingErrorCallback

lib/src/views/chat_input/chat_input.dart

@@ -31,9 +31,13 @@ class ChatInput extends StatefulWidget {
   ///
   /// [onCancelMessage] and [onCancelStt] are optional callbacks for cancelling
   /// message submission or speech-to-text translation respectively.
+  ///
+  /// [onRecordingError] is called when starting or stopping a voice recording
+  /// fails.
   const ChatInput({
     required this.onSendMessage,
     required this.onTranslateStt,
+    required this.onRecordingError,
     this.initialMessage,
     this.onCancelEdit,
     this.onCancelMessage,
@@ -62,6 +66,11 @@ class ChatInput extends StatefulWidget {
   final void Function(XFile file, Iterable<Attachment> attachments)
   onTranslateStt;
 
+  /// Callback function triggered when starting or stopping a voice recording
+  /// fails, e.g. because microphone permission was denied or no microphone is
+  /// available.
+  final void Function(Object error) onRecordingError;
+
   /// The initial message to populate the input field, if any.
   final ChatMessage? initialMessage;
 
@@ -250,11 +259,19 @@ class _ChatInputState extends State<ChatInput> {
   }
 
   Future<void> onStartRecording() async {
-    await _waveController.startRecording();
+    try {
+      await _waveController.startRecording();
+    } catch (error) {
+      if (mounted) widget.onRecordingError(error);
+    }
   }
 
   Future<void> onStopRecording() async {
-    await _waveController.stopRecording();
+    try {
+      await _waveController.stopRecording();
+    } catch (error) {
+      if (mounted) widget.onRecordingError(error);
+    }
   }
 
   Future<void> onRecordingStopped() async {

lib/src/views/llm_chat_view/llm_chat_view.dart

@@ -71,6 +71,10 @@ class LlmChatView extends StatefulWidget {
   /// - [onErrorCallback]: Optional. The action to perform when an
   ///   error occurs during a chat operation. By default, an alert dialog is
   ///   displayed with the error message.
+  /// - [onRecordingErrorCallback]: Optional. The action to perform when
+  ///   starting or stopping a voice recording fails, e.g. because microphone
+  ///   permission was denied. By default, a snackbar is displayed with
+  ///   [LlmChatViewStrings.unableToRecordAudio].
   /// - [cancelMessage]: Optional. The message to display when the user cancels
   ///   a chat operation. Defaults to 'CANCEL'.
   /// - [errorMessage]: Optional. The message to display when an error occurs
@@ -89,6 +93,7 @@ class LlmChatView extends StatefulWidget {
     String? welcomeMessage,
     this.onCancelCallback,
     this.onErrorCallback,
+    this.onRecordingErrorCallback,
     this.cancelMessage = 'CANCEL',
     this.errorMessage = 'ERROR',
     this.enableAttachments = true,
@@ -145,6 +150,15 @@ class LlmChatView extends StatefulWidget {
   final void Function(BuildContext context, LlmException error)?
   onErrorCallback;
 
+  /// The action to perform when starting or stopping a voice recording fails,
+  /// e.g. because microphone permission was denied or no microphone is
+  /// available. The error is the one thrown by the recorder.
+  ///
+  /// By default, a snackbar is displayed with
+  /// [LlmChatViewStrings.unableToRecordAudio].
+  final void Function(BuildContext context, Object error)?
+  onRecordingErrorCallback;
+
   /// The text message to display when the user cancels a chat operation.
   ///
   /// Defaults to 'CANCEL'.
@@ -237,6 +251,7 @@ class _LlmChatViewState extends State<LlmChatView>
                                 ? null
                                 : _onCancelMessage,
                         onTranslateStt: _onTranslateStt,
+                        onRecordingError: _onRecordingError,
                         onCancelStt:
                             _pendingSttResponse == null ? null : _onCancelStt,
                       ),
@@ -365,6 +380,17 @@ class _LlmChatViewState extends State<LlmChatView>
 
   void _onCancelStt() => _pendingSttResponse?.cancel();
 
+  void _onRecordingError(Object error) {
+    if (widget.onRecordingErrorCallback != null) {
+      widget.onRecordingErrorCallback!(context, error);
+    } else {
+      AdaptiveSnackBar.show(
+        context,
+        widget.viewModel.strings.unableToRecordAudio,
+      );
+    }
+  }
+
   Future<void> _showLlmException(LlmException? error) async {
     if (error == null) return;
 

test/voice_recording_error_test.dart

@@ -0,0 +1,75 @@
+// Copyright 2024 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_ai_toolkit/flutter_ai_toolkit.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'smoke_test.dart' show SimpleEchoProvider;
+
+void main() {
+  const recordChannel = MethodChannel('com.llfbandit.record/messages');
+
+  setUp(() {
+    // A recorder that can't get the microphone: no permission, and starting
+    // fails the way it does when the user or browser denies access.
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
+        .setMockMethodCallHandler(recordChannel, (call) async {
+          switch (call.method) {
+            case 'create':
+            case 'dispose':
+              return null;
+            case 'hasPermission':
+              return false;
+            default:
+              throw PlatformException(
+                code: 'record',
+                message: 'Permission denied',
+              );
+          }
+        });
+  });
+
+  tearDown(() {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
+        .setMockMethodCallHandler(recordChannel, null);
+  });
+
+  testWidgets('shows the default message when recording fails to start', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(body: LlmChatView(provider: SimpleEchoProvider())),
+      ),
+    );
+
+    await tester.tap(find.byTooltip('Record Audio'));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Unable to record audio'), findsOneWidget);
+  });
+
+  testWidgets('passes the error to onRecordingErrorCallback', (tester) async {
+    Object? recordingError;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: LlmChatView(
+            provider: SimpleEchoProvider(),
+            onRecordingErrorCallback:
+                (context, error) => recordingError = error,
+          ),
+        ),
+      ),
+    );
+
+    await tester.tap(find.byTooltip('Record Audio'));
+    await tester.pumpAndSettle();
+
+    expect(recordingError, isNotNull);
+    expect(find.text('Unable to record audio'), findsNothing);
+  });
+}