How to test Flutter widgets on different screen sizes?
Not sure why but solution of @rémi-rousselet didn't work for me. I've had to specify screen size using binding.window.physicalSizeTestValue
and binding.window.devicePixelRatioTestValue
so that output is fully deterministic
I've added a little bit more code for flutter beginners like me. Check this:
void main() {
final TestWidgetsFlutterBinding binding =
TestWidgetsFlutterBinding.ensureInitialized();
testWidgets("Basic layout test (mobile device)", (tester) async {
binding.window.physicalSizeTestValue = Size(400, 200);
binding.window.devicePixelRatioTestValue = 1.0;
await tester.pumpWidget(new MyApp());
expect(find.byType(MyHomePage), findsOneWidget);
// etc.
});
}
@rémi-rousselet's solution works perfectly!
In addition if you want to test an orientation change, try this:
const double PORTRAIT_WIDTH = 400.0;
const double PORTRAIT_HEIGHT = 800.0;
const double LANDSCAPE_WIDTH = PORTRAIT_HEIGHT;
const double LANDSCAPE_HEIGHT = PORTRAIT_WIDTH;
final TestWidgetsFlutterBinding binding = TestWidgetsFlutterBinding.ensureInitialized();
await binding.setSurfaceSize(Size(PORTRAIT_WIDTH, PORTRAIT_HEIGHT));
await tester.pumpWidget(MyWidget());
// test in portrait
await binding.setSurfaceSize(Size(LANDSCAPE_WIDTH, LANDSCAPE_HEIGHT));
await tester.pumpAndSettle();
// OrientationBuilder gets triggered
// test in landscape
There is a package called device_preview that can simulate your flutter app running on different devices.
You can specify custom surface size by using WidgetTester
The following code will run a test with a screen size of 42x42
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
void main() {
testWidgets("foo", (tester) async {
tester.binding.window.physicalSizeTestValue = Size(42, 42);
// resets the screen to its original size after the test end
addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
// TODO: do something
});
}