[local_auth] Convert Windows to Pigeon (#7012)

Updates `local_auth_windows` to use Pigeon, and moves to a more platform-tailored and Dart-centric implementation (rather than keeping the previous cross-platform method channel interface that the current implementation was duplicated from):
- Eliminates `deviceSupportsBiometrics` from the platform interface, since it's always the same as `isDeviceSupported`, in favor of doing that mapping in Dart.
- Eliminates `getEnrolledBiometrics` from the platform interface, since it was the same implementation as `isDeviceSupported` just with a different return value, in favor of doing that logic in Dart.
- Moves throwing for the `biometricOnly` option to the Dart side, simplifying the native logic.

Related changes:
- Adds a significant amount of previously-missing Dart unit test coverage.
- Removes the `biometricOnly` UI from the example app, since it will always fail.

Part of flutter/flutter#117912

packages/local_auth/local_auth_windows/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.5
+
+* Switches internal implementation to Pigeon.
+
 ## 1.0.4
 
 * Updates imports for `prefer_relative_imports`.

packages/local_auth/local_auth_windows/example/lib/main.dart

@@ -108,44 +108,6 @@ class _MyAppState extends State<MyApp> {
         () => _authorized = authenticated ? 'Authorized' : 'Not Authorized');
   }
 
-  Future<void> _authenticateWithBiometrics() async {
-    bool authenticated = false;
-    try {
-      setState(() {
-        _isAuthenticating = true;
-        _authorized = 'Authenticating';
-      });
-      authenticated = await LocalAuthPlatform.instance.authenticate(
-        localizedReason:
-            'Scan your fingerprint (or face or whatever) to authenticate',
-        authMessages: <AuthMessages>[const WindowsAuthMessages()],
-        options: const AuthenticationOptions(
-          stickyAuth: true,
-          biometricOnly: true,
-        ),
-      );
-      setState(() {
-        _isAuthenticating = false;
-        _authorized = 'Authenticating';
-      });
-    } on PlatformException catch (e) {
-      print(e);
-      setState(() {
-        _isAuthenticating = false;
-        _authorized = 'Error - ${e.message}';
-      });
-      return;
-    }
-    if (!mounted) {
-      return;
-    }
-
-    final String message = authenticated ? 'Authorized' : 'Not Authorized';
-    setState(() {
-      _authorized = message;
-    });
-  }
-
   Future<void> _cancelAuthentication() async {
     await LocalAuthPlatform.instance.stopAuthentication();
     setState(() => _isAuthenticating = false);
@@ -209,18 +171,6 @@ class _MyAppState extends State<MyApp> {
                           ],
                         ),
                       ),
-                      ElevatedButton(
-                        onPressed: _authenticateWithBiometrics,
-                        child: Row(
-                          mainAxisSize: MainAxisSize.min,
-                          children: <Widget>[
-                            Text(_isAuthenticating
-                                ? 'Cancel'
-                                : 'Authenticate: biometrics only'),
-                            const Icon(Icons.fingerprint),
-                          ],
-                        ),
-                      ),
                     ],
                   ),
               ],

packages/local_auth/local_auth_windows/lib/local_auth_windows.dart

@@ -2,20 +2,25 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/services.dart';
+import 'package:flutter/foundation.dart';
 import 'package:local_auth_platform_interface/local_auth_platform_interface.dart';
-import 'types/auth_messages_windows.dart';
+
+import 'src/messages.g.dart';
 
 export 'package:local_auth_platform_interface/types/auth_messages.dart';
 export 'package:local_auth_platform_interface/types/auth_options.dart';
 export 'package:local_auth_platform_interface/types/biometric_type.dart';
 export 'package:local_auth_windows/types/auth_messages_windows.dart';
 
-const MethodChannel _channel =
-    MethodChannel('plugins.flutter.io/local_auth_windows');
-
 /// The implementation of [LocalAuthPlatform] for Windows.
 class LocalAuthWindows extends LocalAuthPlatform {
+  /// Creates a new plugin implementation instance.
+  LocalAuthWindows({
+    @visibleForTesting LocalAuthApi? api,
+  }) : _api = api ?? LocalAuthApi();
+
+  final LocalAuthApi _api;
+
   /// Registers this class as the default instance of [LocalAuthPlatform].
   static void registerWith() {
     LocalAuthPlatform.instance = LocalAuthWindows();
@@ -28,55 +33,36 @@ class LocalAuthWindows extends LocalAuthPlatform {
     AuthenticationOptions options = const AuthenticationOptions(),
   }) async {
     assert(localizedReason.isNotEmpty);
-    final Map<String, Object> args = <String, Object>{
-      'localizedReason': localizedReason,
-      'useErrorDialogs': options.useErrorDialogs,
-      'stickyAuth': options.stickyAuth,
-      'sensitiveTransaction': options.sensitiveTransaction,
-      'biometricOnly': options.biometricOnly,
-    };
-    args.addAll(const WindowsAuthMessages().args);
-    for (final AuthMessages messages in authMessages) {
-      if (messages is WindowsAuthMessages) {
-        args.addAll(messages.args);
-      }
+
+    if (options.biometricOnly) {
+      throw UnsupportedError(
+          "Windows doesn't support the biometricOnly parameter.");
     }
-    return (await _channel.invokeMethod<bool>('authenticate', args)) ?? false;
+
+    return _api.authenticate(localizedReason);
   }
 
   @override
   Future<bool> deviceSupportsBiometrics() async {
-    return (await _channel.invokeMethod<bool>('deviceSupportsBiometrics')) ??
-        false;
+    // Biometrics are supported on any supported device.
+    return isDeviceSupported();
   }
 
   @override
   Future<List<BiometricType>> getEnrolledBiometrics() async {
-    final List<String> result = (await _channel.invokeListMethod<String>(
-          'getEnrolledBiometrics',
-        )) ??
-        <String>[];
-    final List<BiometricType> biometrics = <BiometricType>[];
-    for (final String value in result) {
-      switch (value) {
-        case 'weak':
-          biometrics.add(BiometricType.weak);
-          break;
-        case 'strong':
-          biometrics.add(BiometricType.strong);
-          break;
-      }
+    // Windows doesn't support querying specific biometric types. Since the
+    // OS considers this a strong authentication API, return weak+strong on
+    // any supported device.
+    if (await isDeviceSupported()) {
+      return <BiometricType>[BiometricType.weak, BiometricType.strong];
     }
-    return biometrics;
+    return <BiometricType>[];
   }
 
   @override
-  Future<bool> isDeviceSupported() async =>
-      (await _channel.invokeMethod<bool>('isDeviceSupported')) ?? false;
+  Future<bool> isDeviceSupported() async => _api.isDeviceSupported();
 
   /// Always returns false as this method is not supported on Windows.
   @override
-  Future<bool> stopAuthentication() async {
-    return false;
-  }
+  Future<bool> stopAuthentication() async => false;
 }

packages/local_auth/local_auth_windows/lib/src/messages.g.dart

@@ -0,0 +1,81 @@
+// Copyright 2013 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.
+// Autogenerated from Pigeon (v5.0.1), do not edit directly.
+// See also: https://pub.dev/packages/pigeon
+// ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
+import 'dart:async';
+import 'dart:typed_data' show Float64List, Int32List, Int64List, Uint8List;
+
+import 'package:flutter/foundation.dart' show ReadBuffer, WriteBuffer;
+import 'package:flutter/services.dart';
+
+class LocalAuthApi {
+  /// Constructor for [LocalAuthApi].  The [binaryMessenger] named argument is
+  /// available for dependency injection.  If it is left null, the default
+  /// BinaryMessenger will be used which routes to the host platform.
+  LocalAuthApi({BinaryMessenger? binaryMessenger})
+      : _binaryMessenger = binaryMessenger;
+  final BinaryMessenger? _binaryMessenger;
+
+  static const MessageCodec<Object?> codec = StandardMessageCodec();
+
+  /// Returns true if this device supports authentication.
+  Future<bool> isDeviceSupported() async {
+    final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+        'dev.flutter.pigeon.LocalAuthApi.isDeviceSupported', codec,
+        binaryMessenger: _binaryMessenger);
+    final List<Object?>? replyList = await channel.send(null) as List<Object?>?;
+    if (replyList == null) {
+      throw PlatformException(
+        code: 'channel-error',
+        message: 'Unable to establish connection on channel.',
+      );
+    } else if (replyList.length > 1) {
+      throw PlatformException(
+        code: replyList[0]! as String,
+        message: replyList[1] as String?,
+        details: replyList[2],
+      );
+    } else if (replyList[0] == null) {
+      throw PlatformException(
+        code: 'null-error',
+        message: 'Host platform returned null value for non-null return value.',
+      );
+    } else {
+      return (replyList[0] as bool?)!;
+    }
+  }
+
+  /// Attempts to authenticate the user with the provided [localizedReason] as
+  /// the user-facing explanation for the authorization request.
+  ///
+  /// Returns true if authorization succeeds, false if it is attempted but is
+  /// not successful, and an error if authorization could not be attempted.
+  Future<bool> authenticate(String arg_localizedReason) async {
+    final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+        'dev.flutter.pigeon.LocalAuthApi.authenticate', codec,
+        binaryMessenger: _binaryMessenger);
+    final List<Object?>? replyList =
+        await channel.send(<Object?>[arg_localizedReason]) as List<Object?>?;
+    if (replyList == null) {
+      throw PlatformException(
+        code: 'channel-error',
+        message: 'Unable to establish connection on channel.',
+      );
+    } else if (replyList.length > 1) {
+      throw PlatformException(
+        code: replyList[0]! as String,
+        message: replyList[1] as String?,
+        details: replyList[2],
+      );
+    } else if (replyList[0] == null) {
+      throw PlatformException(
+        code: 'null-error',
+        message: 'Host platform returned null value for non-null return value.',
+      );
+    } else {
+      return (replyList[0] as bool?)!;
+    }
+  }
+}

packages/local_auth/local_auth_windows/pigeons/copyright.txt

@@ -0,0 +1,3 @@
+Copyright 2013 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.

packages/local_auth/local_auth_windows/pigeons/messages.dart

@@ -0,0 +1,27 @@
+// Copyright 2013 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:pigeon/pigeon.dart';
+
+@ConfigurePigeon(PigeonOptions(
+  dartOut: 'lib/src/messages.g.dart',
+  cppOptions: CppOptions(namespace: 'local_auth_windows'),
+  cppHeaderOut: 'windows/messages.g.h',
+  cppSourceOut: 'windows/messages.g.cpp',
+  copyrightHeader: 'pigeons/copyright.txt',
+))
+@HostApi()
+abstract class LocalAuthApi {
+  /// Returns true if this device supports authentication.
+  @async
+  bool isDeviceSupported();
+
+  /// Attempts to authenticate the user with the provided [localizedReason] as
+  /// the user-facing explanation for the authorization request.
+  ///
+  /// Returns true if authorization succeeds, false if it is attempted but is
+  /// not successful, and an error if authorization could not be attempted.
+  @async
+  bool authenticate(String localizedReason);
+}

packages/local_auth/local_auth_windows/pubspec.yaml

@@ -2,7 +2,7 @@ name: local_auth_windows
 description: Windows implementation of the local_auth plugin.
 repository: https://github.com/flutter/plugins/tree/main/packages/local_auth/local_auth_windows
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+local_auth%22
-version: 1.0.4
+version: 1.0.5
 
 environment:
   sdk: ">=2.14.0 <3.0.0"
@@ -24,3 +24,4 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
+  pigeon: ^5.0.1