[federated_plugin] adds platform interface implementation and plugin implementation for Android (#503)

experimental/federated_plugin/federated_plugin/example/lib/main.dart

@@ -2,60 +2,74 @@
 // 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/material.dart';
-import 'package:flutter/services.dart';
 import 'package:federated_plugin/federated_plugin.dart';
+import 'package:flutter/material.dart';
 
 void main() {
   runApp(MyApp());
 }
 
-class MyApp extends StatefulWidget {
-  @override
-  _MyAppState createState() => _MyAppState();
-}
-
-class _MyAppState extends State<MyApp> {
-  String _platformVersion = 'Unknown';
-
-  @override
-  void initState() {
-    super.initState();
-    initPlatformState();
-  }
-
-  // Platform messages are asynchronous, so we initialize in an async method.
-  Future<void> initPlatformState() async {
-    String platformVersion;
-    // Platform messages may fail, so we use a try/catch PlatformException.
-    try {
-      platformVersion = await FederatedPlugin.platformVersion;
-    } on PlatformException {
-      platformVersion = 'Failed to get platform version.';
-    }
-
-    // If the widget was removed from the tree while the asynchronous platform
-    // message was in flight, we want to discard the reply rather than calling
-    // setState to update our non-existent appearance.
-    if (!mounted) return;
-
-    setState(() {
-      _platformVersion = platformVersion;
-    });
-  }
-
+class MyApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
-      home: Scaffold(
-        appBar: AppBar(
-          title: const Text('Plugin example app'),
-        ),
-        body: Center(
-          child: Text('Running on: $_platformVersion\n'),
-        ),
+      home: HomePage(),
+    );
+  }
+}
+
+/// Demonstrates how to use the getLocation method from federated_plugin to access
+/// location data.
+class HomePage extends StatefulWidget {
+  @override
+  _HomePageState createState() => _HomePageState();
+}
+
+class _HomePageState extends State<HomePage> {
+  Location location;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Federated Plugin Demo'),
+      ),
+      body: Builder(
+        builder: (context) {
+          return Center(
+            child: Column(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                location == null
+                    ? SizedBox.shrink()
+                    : Text(
+                        'Latitude: ${location.latitude}\n'
+                        'Longitude: ${location.longitude}',
+                        style: Theme.of(context).textTheme.headline5,
+                      ),
+                SizedBox(height: 16),
+                RaisedButton(
+                  child: Text('Get Location'),
+                  onPressed: () async {
+                    try {
+                      final result = await getLocation();
+                      setState(() {
+                        location = result;
+                      });
+                    } catch (error) {
+                      Scaffold.of(context).showSnackBar(
+                        SnackBar(
+                          backgroundColor: Theme.of(context).primaryColor,
+                          content: Text(error.message as String),
+                        ),
+                      );
+                    }
+                  },
+                ),
+              ],
+            ),
+          );
+        },
       ),
     );
   }

experimental/federated_plugin/federated_plugin/example/pubspec.lock

@@ -64,6 +64,13 @@ packages:
       relative: true
     source: path
     version: "0.0.1"
+  federated_plugin_platform_interface:
+    dependency: transitive
+    description:
+      path: "../../federated_plugin_platform_interface"
+      relative: true
+    source: path
+    version: "0.0.1"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -102,6 +109,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.9.2"
+  plugin_platform_interface:
+    dependency: transitive
+    description:
+      name: plugin_platform_interface
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.2"
   sky_engine:
     dependency: transitive
     description: flutter

experimental/federated_plugin/federated_plugin/example/test/widget_test.dart

@@ -2,23 +2,35 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:federated_plugin/federated_plugin.dart';
+import 'package:federated_plugin_example/main.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 
-import 'package:federated_plugin_example/main.dart';
-
 void main() {
-  testWidgets('Verify Platform version', (tester) async {
-    // Build our app and trigger a frame.
-    await tester.pumpWidget(MyApp());
+  group('federated plugin demo tests', () {
+    final location = Location(latitude: 131.0, longitude: 221.0);
+    setUpAll(() {
+      MethodChannel('location').setMockMethodCallHandler((call) async {
+        if (call.method == 'getLocation') {
+          return [location.longitude, location.latitude];
+        }
+      });
+    });
 
-    // Verify that platform version is retrieved.
-    expect(
-      find.byWidgetPredicate(
-        (widget) => widget is Text &&
-                           widget.data.startsWith('Running on:'),
-      ),
-      findsOneWidget,
-    );
+    testWidgets('get location from platform', (tester) async {
+      await tester.pumpWidget(MyApp());
+
+      // Tap button to get location from platform.
+      await tester.tap(find.byType(RaisedButton));
+      await tester.pumpAndSettle();
+
+      expect(
+        find.text('Latitude: ${location.latitude}\n'
+            'Longitude: ${location.longitude}'),
+        findsOneWidget,
+      );
+    });
   });
 }