Integration tests and CI

        /\          integration tests: few, slow, whole app on a device
       /  \
      /----\        widget tests: some, fast, one screen at a time
     /      \
    /--------\      unit tests: many, very fast, pure logic

# pubspec.yaml
dev_dependencies:
  integration_test:
    sdk: flutter
  flutter_test:
    sdk: flutter

// integration_test/order_flow_test.dart
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:integration_test/integration_test.dart';
import 'package:chai_shop/main.dart' as app;

void main() {
  IntegrationTestWidgetsFlutterBinding.ensureInitialized();

  testWidgets('user can add chai and see it in the cart', (tester) async {
    app.main();                                    // start the real app
    await tester.pumpAndSettle();

    await tester.tap(find.text('Masala chai'));
    await tester.pumpAndSettle();
    await tester.tap(find.text('Add to cart'));
    await tester.tap(find.byIcon(Icons.shopping_cart));
    await tester.pumpAndSettle();

    expect(find.text('Masala chai x1'), findsOneWidget);
  });
}

flutter test integration_test                       # on the connected device or emulator
flutter test integration_test/order_flow_test.dart

flutter analyze          # finds errors, warnings and lint issues without running the app
dart format .            # formats all Dart files in the standard style
dart format --output=none --set-exit-if-changed .   # CI check: fail if anything is unformatted

name: flutter-ci
on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: subosito/flutter-action@v2      # a widely used community action to install Flutter
        with:
          channel: stable
      - run: flutter pub get
      - run: dart format --output=none --set-exit-if-changed .
      - run: flutter analyze
      - run: flutter test