testWidgets

Write widget render tests with testWidgets.

testWidgets

testWidgets registers a widget test. Inside it, you use the WidgetTester to render a widget by calling pumpWidget, then verify with expect. The test body is async because pumpWidget returns a Future.

testWidgets('shows button', (tester) async {
  await tester.pumpWidget(MaterialApp(home: MyButton()));
  expect(find.byType(ElevatedButton), findsOneWidget);
});

expect and Matcher

expect compares an actual value against an expected value. The first parameter is the actual value (usually a Finder), the second is a Matcher. findsOneWidget verifies exactly one widget, findsNothing verifies none, and findsNWidgets(3) verifies exactly N.

Exercise Write a button test

In main, write a testWidgets test named 'buton gosterilir'. Render MaterialApp(home: ElevatedButton(onPressed: () {}, child: Text('Tikla'))) with pumpWidget. Verify with find.byType(ElevatedButton) and findsOneWidget. Finally print 'test tanimlandi'.

Show example solution

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

void main() {
  testWidgets('buton gosterilir', (tester) async {
    await tester.pumpWidget(
      MaterialApp(
        home: ElevatedButton(
          onPressed: () {},
          child: const Text('Tikla'),
        ),
      ),
    );
    expect(find.byType(ElevatedButton), findsOneWidget);
  });
  print('test tanimlandi');
}

Test yourself

Why is await used before the pumpWidget call?
- Because it returns void
- Because it returns Widget
- Because it returns int
- Because it returns a Future and we must wait
Show answer

Because it returns a Future and we must wait — pumpWidget returns a Future; await is used so the render completes before continuing.

pumpWidget call

await tester.____(MaterialApp(home: MyButton()));

Show answer

await tester.pumpWidget(MaterialApp(home: MyButton()));

testWidgets matches

testWidgets

Registers a widget test
WidgetTester

Test tool
pumpWidget

Renders a widget
expect

Compares

Next lesson: pump and settle

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