According to the answers here, I tried this in my test:
import 'dart:ui' as ui;
testWidgets('test', (tester) async{
// setup the physical size
tester.binding.window.physicalSizeTestValue = const Size(1366.0, 673.0);
tester.binding.window.devicePixelRatioTestValue = 1.0;
// reset the edited settings after the test ends
addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
addTearDown(tester.binding.window.clearDevicePixelRatioTestValue);
//////////// For debugging
var physicalSize = ui. window.physicalSize; // debugger shows Size(2400.0, 1800.0)
var pixelRatio = ui.window.devicePixelRatio; // debugger shows 3.0
///////////
await tester.runAsync(() async {
... // code that depends on the screen size (window.size and window.devicePixelRatio)
});
...
});
