samples/add_to_app/flutter_module/test/widget_test.dart

// This is a basic Flutter widget test.
//
// To perform an interaction with a widget in your test, use the WidgetTester
// utility that Flutter provides. For example, you can send tap and scroll
// gestures. You can also use WidgetTester to find child widgets in the widget
// tree, read text, and verify that the values of widget properties are correct.

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

import 'package:flutter_module/main.dart';
import 'package:provider/provider.dart';

class MockCounterModel extends ChangeNotifier implements CounterModel {
  int _count = 0;

  int get count => _count;

  void increment() {
    _count++;
    notifyListeners();
  }
}

void main() {
  testWidgets('MiniView smoke test', (WidgetTester tester) async {
    // Build our app and trigger a frame.
    await tester.pumpWidget(
      MaterialApp(
        home: ChangeNotifierProvider<CounterModel>.value(
          value: MockCounterModel(),
          child: Contents(),
        ),
      ),
    );

    // Verify that our counter starts at 0.
    expect(find.text('Taps: 0'), findsOneWidget);
    expect(find.text('Taps: 1'), findsNothing);

    // Tap the '+' icon and trigger a frame.
    await tester.tap(find.text('Tap me!'));
    await tester.pump();

    // Verify that our counter has incremented.
    expect(find.text('Taps: 0'), findsNothing);
    expect(find.text('Taps: 1'), findsOneWidget);
  });
}