Writing Widget Tests

import 'package:flutter_test/flutter_test.dart';
import 'package:myapp/main.dart';

void main() {
  testWidgets('Counter increments smoke test', (WidgetTester tester) async {
    // Build our app and trigger a frame.
    await tester.pumpWidget(MyApp());

    // Verify that our counter starts at 0.
    expect(find.text('0'), findsOneWidget);
  });
}

testWidgets('Button tap increments counter', (WidgetTester tester) async {
  await tester.pumpWidget(MyApp());

  // Tap the button
  await tester.tap(find.byType(ElevatedButton));
  await tester.pump();

  // Verify the counter updated
  expect(find.text('1'), findsOneWidget);
});

testWidgets('TextField updates text', (WidgetTester tester) async {
  await tester.pumpWidget(MyApp());

  // Enter text into the field
  await tester.enterText(find.byType(TextField), 'Flutter');
  await tester.pump();

  // Verify the text is updated
  expect(find.text('Flutter'), findsOneWidget);
});

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

void main() {
  testWidgets('Counter increments smoke test', (WidgetTester tester) async {
    // Build the widget
    await tester.pumpWidget(MaterialApp(home: Text('Hello World')));

    // Verify the text
    expect(find.text('Hello World'), findsOneWidget);
  });
}

testWidgets('Find Text widget', (WidgetTester tester) async {
  await tester.pumpWidget(MyApp());

  final textFinder = find.byType(Text);
  expect(textFinder, findsOneWidget);
});

testWidgets('Find widget by key', (WidgetTester tester) async {
  await tester.pumpWidget(MyApp());

  final keyFinder = find.byKey(Key('saveButton'));
  expect(keyFinder, findsOneWidget);
});

testWidgets('Find widget by text', (WidgetTester tester) async {
  await tester.pumpWidget(MyApp());

  final textFinder = find.byText('Welcome');
  expect(textFinder, findsOneWidget);
});

testWidgets('taps button and updates text', (WidgetTester tester) async {
  await tester.pumpWidget(MyApp());
  final button = find.text('Tap Me');
  expect(find.text('Hello'), findsNothing);
  await tester.tap(button);
  await tester.pumpAndSettle();
  expect(find.text('Hello'), findsOneWidget);
});

testWidgets('drags slider', (WidgetTester tester) async {
  await tester.pumpWidget(MyApp());
  final slider = find.byType(Slider);
  await tester.drag(slider, const Offset(50, 0));
  await tester.pumpAndSettle();
  expect(find.text('Value: 50'), findsOneWidget);
});

testWidgets('types text into field', (WidgetTester tester) async {
  await tester.pumpWidget(MyApp());
  final textField = find.byType(TextField);
  await tester.enterText(textField, 'Hello World');
  await tester.pumpAndSettle();
  expect(find.text('Hello World'), findsOneWidget);
});

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

void main() {
  testWidgets('Verify widget properties', (WidgetTester tester) async {
    await tester.pumpWidget(
      MaterialApp(
        home: Scaffold(
          body: Text('Hello World'),
        ),
      ),
    );

    // Verify text content
    expect(find.text('Hello World'), findsOneWidget);

    // Verify visibility
    expect(find.text('Hello World'), findsOneWidget);
  });
}

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

void main() {
  testWidgets('Rebuilds when counter changes', (WidgetTester tester) async {
    await tester.pumpWidget(
      MaterialApp(
        home: Scaffold(
          body: CounterWidget(),
        ),
      ),
    );

    // Initial state
    expect(tester.text(find.text('0')), findsOneWidget);

    // Simulate a state change
    await tester.tap(find.byType(ElevatedButton));
    await tester.pump();

    // Verify rebuild
    expect(tester.text(find.text('1')), findsOneWidget);
  });
}

class CounterWidget extends StatefulWidget {
  @override
  State<CounterWidget> createState() => _CounterWidgetState();
}

class _CounterWidgetState extends State<CounterWidget> {
  int count = 0;

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text(count.toString()),
        ElevatedButton(
          onPressed: () {
            setState(() {
              count++;
            });
          },
          child: Text('Increment'),
        ),
      ],
    );
  }
}

import 'package:flutter_test/flutter_test.dart';
import 'package:my_app/main.dart';

void main() {
  testWidgets('Verify text is displayed', (WidgetTester tester) async {
    await tester.pumpWidget(MyApp());

    // Find a Text widget with specific content
    expect(find.byText('Welcome'), findsOneWidget);
  });
}

import 'package:flutter_test/flutter_test.dart';
import 'package:my_app/main.dart';

void main() {
  testWidgets('Verify widget count', (WidgetTester tester) async {
    await tester.pumpWidget(MyApp());

    // Check that there are exactly 3 Text widgets
    expect(find.byType(Text), findsNWidgets(3));
  });
}

testWidgets('Fetches and displays data', (WidgetTester tester) async {
  final mockData = {'name': 'Flutter'};
  when(mockApi.fetchData()).thenAnswer((_) async => mockData);

  await tester.pumpWidget(MyAsyncWidget(api: mockApi));
  await tester.pumpAndSettle();

  expect(find.text('Flutter'), findsOneWidget);
});

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

void main() {
  testWidgets('MyWidget golden test', (WidgetTester tester) async {
    await tester.pumpWidget(
      MaterialApp(
        home: MyWidget(),
      ),
    );

    await expectLater(
      find.byType(MyWidget),
      matchesGoldenFile('golden/my_widget.png'),
    );
  });
}

// Using mockito for HTTP client mocking
import 'package:mockito/mockito.dart';
import 'package:http/http.dart' as http;

class MockHttpClient extends Mock implements http.Client {}

// In test
final mockClient = MockHttpClient();
when(mockClient.get(any)).thenAnswer(
  (_) async => http.Response('{"name": "Flutter"}', 200),
);

// Use mockClient in widget test