Allow user to handle PlatformExceptions caught by FirebaseAnalyticsOb…

…server._sendScreenView(). (firebase#993)

packages/firebase_analytics/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.1.0
+
+* Allow user to handle `PlatformException`s caught by `FirebaseAnalyticsObserver._sendScreenView()`.
+
 ## 1.0.6
 
 * Allow user ID to be set to null.

packages/firebase_analytics/lib/observer.dart

@@ -2,6 +2,7 @@
 // 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:meta/meta.dart';
 import 'package:flutter/widgets.dart';
 
@@ -19,8 +20,8 @@ String defaultNameExtractor(RouteSettings settings) => settings.name;
 /// A [NavigatorObserver] that sends events to Firebase Analytics when the
 /// currently active [PageRoute] changes.
 ///
-/// When a route is pushed or poped, [nameExtractor] is used to extract a name
-/// from [RouteSettings] of the now active route and that name is send to
+/// When a route is pushed or popped, [nameExtractor] is used to extract a name
+/// from [RouteSettings] of the now active route and that name is sent to
 /// Firebase.
 ///
 /// The following operations will result in sending a screen view event:
@@ -49,18 +50,39 @@ String defaultNameExtractor(RouteSettings settings) => settings.name;
 /// [PageRouteAware] and subscribing it to [FirebaseAnalyticsObserver]. See the
 /// [PageRouteObserver] docs for an example.
 class FirebaseAnalyticsObserver extends RouteObserver<PageRoute<dynamic>> {
+  /// Creates a [NavigatorObserver] that sends events to [FirebaseAnalytics].
+  ///
+  /// When a route is pushed or popped, [nameExtractor] is used to extract a
+  /// name from [RouteSettings] of the now active route and that name is sent to
+  /// Firebase. Defaults to `defaultNameExtractor`.
+  ///
+  /// If a [PlatformException] is thrown while the observer attempts to send the
+  /// active route to [analytics], `onError` will be called with the
+  /// exception. If `onError` is omitted, the exception will be printed using
+  /// `debugPrint()`.
   FirebaseAnalyticsObserver({
     @required this.analytics,
     this.nameExtractor = defaultNameExtractor,
-  });
+    Function(PlatformException error) onError,
+  }) : _onError = onError;
 
   final FirebaseAnalytics analytics;
   final ScreenNameExtractor nameExtractor;
+  final void Function(PlatformException error) _onError;
 
   void _sendScreenView(PageRoute<dynamic> route) {
     final String screenName = nameExtractor(route.settings);
     if (screenName != null) {
-      analytics.setCurrentScreen(screenName: screenName);
+      analytics.setCurrentScreen(screenName: screenName).catchError(
+        (Object error) {
+          if (_onError == null) {
+            debugPrint('$FirebaseAnalyticsObserver: $error');
+          } else {
+            _onError(error);
+          }
+        },
+        test: (Object error) => error is PlatformException,
+      );
     }
   }
 

packages/firebase_analytics/pubspec.yaml

@@ -3,7 +3,7 @@ description: Flutter plugin for Google Analytics for Firebase, an app measuremen
   solution that provides insight on app usage and user engagement on Android and iOS.
 author: Flutter Team <[email protected]>
 homepage: https://github.com/flutter/plugins/tree/master/packages/firebase_analytics
-version: 1.0.6
+version: 1.1.0
 
 flutter:
   plugin:

packages/firebase_analytics/test/observer_test.dart

@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
+import 'package:flutter/services.dart';
 import 'package:mockito/mockito.dart';
 import 'package:test/test.dart';
 
@@ -14,10 +17,23 @@ void main() {
   group('FirebaseAnalyticsObserver', () {
     FirebaseAnalytics analytics;
     FirebaseAnalyticsObserver observer;
+    final List<String> printLog = <String>[];
+
+    void overridePrint(void Function() func) {
+      final ZoneSpecification spec =
+          ZoneSpecification(print: (_, __, ___, String msg) {
+        // Add to log instead of printing to stdout
+        printLog.add(msg);
+      });
+      return Zone.current.fork(specification: spec).run(func);
+    }
 
     setUp(() {
+      printLog.clear();
       analytics = MockFirebaseAnalytics();
       observer = FirebaseAnalyticsObserver(analytics: analytics);
+      when(analytics.setCurrentScreen(screenName: anyNamed('screenName')))
+          .thenAnswer((Invocation invocation) => Future<void>.value());
     });
 
     test('setCurrentScreen on route pop', () {
@@ -53,6 +69,66 @@ void main() {
 
       verify(analytics.setCurrentScreen(screenName: 'foo')).called(1);
     });
+
+    test('handles only ${PlatformException}s', () async {
+      observer = FirebaseAnalyticsObserver(
+        analytics: analytics,
+        nameExtractor: (RouteSettings settings) => 'foo',
+      );
+
+      final PageRoute<dynamic> route = MockPageRoute();
+      final PageRoute<dynamic> previousRoute = MockPageRoute();
+
+      // Throws non-PlatformExceptions
+      when(analytics.setCurrentScreen(screenName: anyNamed('screenName')))
+          .thenThrow(ArgumentError());
+
+      expect(() => observer.didPush(route, previousRoute), throwsArgumentError);
+
+      // Print PlatformExceptions
+      Future<void> throwPlatformException() async =>
+          throw PlatformException(code: 'a');
+
+      when(analytics.setCurrentScreen(screenName: anyNamed('screenName')))
+          .thenAnswer((Invocation invocation) => throwPlatformException());
+
+      overridePrint(() => observer.didPush(route, previousRoute));
+
+      await pumpEventQueue();
+      expect(
+        printLog,
+        <String>['$FirebaseAnalyticsObserver: ${PlatformException(code: 'a')}'],
+      );
+    });
+
+    test('runs onError', () async {
+      PlatformException passedException;
+
+      final void Function(PlatformException error) handleError =
+          (PlatformException error) {
+        passedException = error;
+      };
+
+      observer = FirebaseAnalyticsObserver(
+        analytics: analytics,
+        nameExtractor: (RouteSettings settings) => 'foo',
+        onError: handleError,
+      );
+
+      final PageRoute<dynamic> route = MockPageRoute();
+      final PageRoute<dynamic> previousRoute = MockPageRoute();
+
+      final PlatformException thrownException = PlatformException(code: 'b');
+      Future<void> throwPlatformException() async => throw thrownException;
+
+      when(analytics.setCurrentScreen(screenName: anyNamed('screenName')))
+          .thenAnswer((Invocation invocation) => throwPlatformException());
+
+      observer.didPush(route, previousRoute);
+
+      await pumpEventQueue();
+      expect(passedException, thrownException);
+    });
   });
 }