What is flutter_test?

Start writing widget tests with flutter_test.

What is flutter_test?

The flutter_test package is the official testing framework for Flutter widgets. The testWidgets function sets up a test environment, Finder locates widgets, and expect verifies them. Tests live in the test/ folder with the _test.dart extension.

import 'package:flutter_test/flutter_test.dart';

void main() {
  testWidgets('shows title', (tester) async {
    await tester.pumpWidget(MyApp());
    expect(find.text('Hello'), findsOneWidget);
  });
}

Finding widgets with Finder

Finder is used to search the widget tree. find.text matches by text, find.byType by widget type, and find.byKey by key. You check the Finder result with expect against values like findsOneWidget or findsNothing.

Exercise First widget test

In main, write a testWidgets test named 'metin gosterilir'. Render MaterialApp(home: Text('Merhaba')) with pumpWidget. Verify with find.text('Merhaba') and findsOneWidget. Finally print 'test tanimlandi'.

Show example solution

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

void main() {
  testWidgets('metin gosterilir', (tester) async {
    await tester.pumpWidget(
      const MaterialApp(home: Text('Merhaba')),
    );
    expect(find.text('Merhaba'), findsOneWidget);
  });
  print('test tanimlandi');
}

Test yourself

In which folder are test files placed?
- assets/
- test/
- lib/
- bin/
Show answer

test/ — Flutter tests live in the test/ folder with the _test.dart extension; the flutter test command scans that folder.

Search for text with find

expect(find.____('Merhaba'), findsOneWidget);

Show answer

expect(find.text('Merhaba'), findsOneWidget);

flutter_test parts

flutter_test

Testing framework
testWidgets

Sets up test environment
Finder

Widget finding
expect

Verification

Next lesson: testWidgets

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