การทดสอบ: ยูนิตเทสต์ของ Dart และ widget test

import 'package:flutter/foundation.dart';

abstract interface class ScoreRepository {
  Future<int> fetchBest();
}

class ScoreController extends ChangeNotifier {
  ScoreController(this._repository);

  final ScoreRepository _repository;

  int? best;
  Object? error;

  Future<void> load() async {
    try {
      best = await _repository.fetchBest();
      error = null;
    } on Exception catch (e) {
      error = e;
    }
    notifyListeners();
  }
}

import 'package:flutter_test/flutter_test.dart';

class FakeScoreRepository implements ScoreRepository {
  int calls = 0;
  bool failNextCall = false;

  @override
  Future<int> fetchBest() async {
    calls++;
    if (failNextCall) {
      failNextCall = false;
      throw Exception('network unavailable');
    }
    return 42;
  }
}

void main() {
  late FakeScoreRepository repository;
  late ScoreController controller;

  setUp(() {
    repository = FakeScoreRepository();
    controller = ScoreController(repository);
  });

  test('exposes the best score', () async {
    await controller.load();

    expect(controller.best, 42);
    expect(controller.error, isNull);
    expect(repository.calls, 1);
  });

  test('captures an error then recovers', () async {
    repository.failNextCall = true;

    await controller.load();
    expect(controller.error, isA<Exception>());

    await controller.load();
    expect(controller.best, 42);
    expect(controller.error, isNull);
  });

  test('notifies its listeners', () async {
    var notifications = 0;
    controller.addListener(() => notifications++);

    await controller.load();

    expect(notifications, 1);
  });
}

import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';

class BadgeScreen extends StatefulWidget {
  const BadgeScreen({super.key});

  @override
  State<BadgeScreen> createState() => _BadgeScreenState();
}

class _BadgeScreenState extends State<BadgeScreen> {
  bool _visible = true;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          if (_visible) const Text('New'),
          IconButton(
            icon: const Icon(Icons.close),
            onPressed: () =>
                setState(() => _visible = false),
          ),
        ],
      ),
    );
  }
}

void main() {
  testWidgets('hides the badge after the tap',
      (tester) async {
    await tester.pumpWidget(
      const MaterialApp(home: BadgeScreen()),
    );
    expect(find.text('New'), findsOneWidget);

    await tester.tap(find.byIcon(Icons.close));
    await tester.pump();

    expect(find.text('New'), findsNothing);
  });
}

flutter test
flutter test test/score_controller_test.dart
flutter test --coverage
flutter test --update-goldens