[local_auth] Fix iOS crash when no localizedReason (flutter#3780)

Author: enricobenedos

packages/local_auth/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.1.4
+
+* Add debug assertion that `localizedReason` in `LocalAuthentication.authenticateWithBiometrics`  must not be empty.
+
 ## 1.1.3
 
 * Fix crashes due to threading issues in iOS implementation.

packages/local_auth/lib/local_auth.dart

@@ -59,7 +59,7 @@ class LocalAuthentication {
   ///
   /// [localizedReason] is the message to show to user while prompting them
   /// for authentication. This is typically along the lines of: 'Please scan
-  /// your finger to access MyApp.'
+  /// your finger to access MyApp.'. This must not be empty.
   ///
   /// [useErrorDialogs] = true means the system will attempt to handle user
   /// fixable issues encountered while authenticating. For instance, if
@@ -100,7 +100,8 @@ class LocalAuthentication {
     bool sensitiveTransaction = true,
     bool biometricOnly = false,
   }) async {
-    assert(localizedReason != null);
+    assert(localizedReason.isNotEmpty);
+
     final Map<String, Object> args = <String, Object>{
       'localizedReason': localizedReason,
       'useErrorDialogs': useErrorDialogs,

packages/local_auth/pubspec.yaml

@@ -2,7 +2,7 @@ name: local_auth
 description: Flutter plugin for Android and iOS devices to allow local
   authentication via fingerprint, touch ID, face ID, passcode, pin, or pattern.
 homepage: https://github.com/flutter/plugins/tree/master/packages/local_auth
-version: 1.1.3
+version: 1.1.4
 
 flutter:
   plugin:

packages/local_auth/test/local_auth_test.dart

@@ -73,6 +73,17 @@ void main() {
         );
       });
 
+      test('authenticate with no localizedReason on iOS.', () async {
+        setMockPathProviderPlatform(FakePlatform(operatingSystem: 'ios'));
+        await expectLater(
+          localAuthentication.authenticate(
+            localizedReason: '',
+            biometricOnly: true,
+          ),
+          throwsAssertionError,
+        );
+      });
+
       test('authenticate with no sensitive transaction.', () async {
         setMockPathProviderPlatform(FakePlatform(operatingSystem: 'android'));
         await localAuthentication.authenticate(