[platform_channels] adds BasicMessageChannel Demo (#484)

platform_channels/test/src/add_pet_details_test.dart

@@ -0,0 +1,37 @@
+// Copyright 2020 The Flutter team. 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_test/flutter_test.dart';
+import 'package:platform_channels/src/add_pet_details.dart';
+
+void main() {
+  group('AddPetDetails tests', () {
+    var petList = <Map>[];
+
+    setUpAll(() {
+      BasicMessageChannel<dynamic>('jsonMessageCodecDemo', JSONMessageCodec())
+          .setMockMessageHandler((dynamic message) async {
+        petList.add(message as Map);
+      });
+    });
+
+    testWidgets('Enter pet details', (tester) async {
+      await tester.pumpWidget(MaterialApp(home: AddPetDetails()));
+
+      // Enter the breed of cat.
+      await tester.enterText(find.byType(TextField), 'Persian');
+      // Select cat from the pet type.
+      await tester.tap(find.text('Cat'));
+
+      // Initially the list will be empty.
+      expect(petList, isEmpty);
+      await tester.tap(find.byIcon(Icons.add));
+
+      expect(petList, isNotEmpty);
+      expect(petList.last['breed'], 'Persian');
+    });
+  });
+}

platform_channels/test/src/pet_list_screen_test.dart

@@ -0,0 +1,83 @@
+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:convert';
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:platform_channels/src/pet_list_message_channel.dart';
+import 'package:platform_channels/src/pet_list_screen.dart';
+
+void main() {
+  group('PetListScreen tests', () {
+    final basicMessageChannel =
+        BasicMessageChannel('stringCodecDemo', StringCodec());
+
+    var petList = [
+      {
+        'petType': 'Dog',
+        'breed': 'Pug',
+      }
+    ];
+
+    PetListModel petListModel;
+
+    setUpAll(() {
+      // Mock for the pet list received from the platform.
+      basicMessageChannel.setMockMessageHandler((message) async {
+        petListModel = PetListModel.fromJson(message);
+        return;
+      });
+
+      // Mock for the index received from the Dart to delete the pet details,
+      // and send the updated pet list back to Dart.
+      BasicMessageChannel('binaryCodecDemo', BinaryCodec())
+          .setMockMessageHandler((message) async {
+        // Convert the ByteData to String.
+        final index = utf8.decoder.convert(message.buffer
+            .asUint8List(message.offsetInBytes, message.lengthInBytes));
+
+        // Remove the pet details at the given index.
+        petList.removeAt(int.parse(index));
+
+        // Send the updated petList back.
+        final map = {'petList': petList};
+        await basicMessageChannel.send(json.encode(map));
+        return;
+      });
+    });
+
+    test('convert json message to PetListModel', () {
+      TestWidgetsFlutterBinding.ensureInitialized();
+
+      // Initially petListModel will be null.
+      expect(petListModel, isNull);
+
+      // Send the pet list using BasicMessageChannel.
+      final map = {'petList': petList};
+      basicMessageChannel.send(json.encode(map));
+
+      // Get the details of first pet.
+      final petDetails = petListModel.petList.first;
+      expect(petDetails.petType, 'Dog');
+      expect(petDetails.breed, 'Pug');
+    });
+
+    testWidgets('BuildPetList test', (tester) async {
+      await tester.pumpWidget(MaterialApp(
+        home: Scaffold(
+          body: BuildPetList(petListModel.petList),
+        ),
+      ));
+
+      expect(find.text('Pet type: Dog'), findsOneWidget);
+      expect(find.text('Pet breed: Pug'), findsOneWidget);
+
+      // Delete the pet details.
+      await tester.tap(find.byIcon(Icons.delete).first);
+      expect(petListModel.petList, isEmpty);
+    });
+  });
+}