setTestViewForDevice function

VoidCallback setTestViewForDevice(DeviceInfo? device, Orientation orientation)

Temporarily changes the test environment to simulate a specific device.

This is a lower-level function that snap uses internally. You typically don't need to call this directly - just use snap with device settings instead.

Returns a callback to restore the original test environment:

final restore = setTestViewForDevice(Devices.ios.iPhone16Pro);

// Test environment now simulates iPhone 16 Pro
await tester.pumpWidget(MyApp());

// Restore original test environment
restore();

The snap function handles this automatically, so prefer using snap with SnaptestSettings instead of calling this directly.

Implementation

VoidCallback setTestViewForDevice(
  DeviceInfo? device,
  Orientation orientation,
) {
  final implicitView =
      TestWidgetsFlutterBinding.instance.platformDispatcher.implicitView!;
  final previousTargetPlatform = debugDefaultTargetPlatformOverride;

  void restore() {
    debugDefaultTargetPlatformOverride = previousTargetPlatform;
    implicitView
      ..resetPhysicalSize()
      ..resetPadding()
      ..resetDevicePixelRatio();
  }

  if (device == null) {
    return () {};
  }

  // Get screen size based on orientation
  var screenSize = device.screenSize;
  var safeAreas = device.safeAreas;

  if (device.isLandscape(orientation)) {
    // Swap width and height for landscape
    screenSize = screenSize.flipped;
    // Rotate safe areas for landscape (90 degrees clockwise)
    // Portrait: top=notch, right=0, bottom=home, left=0
    // Landscape: left=notch, top=0, right=home, bottom=0
    safeAreas = device.rotatedSafeAreas!;
  }

  implicitView
    ..physicalSize = screenSize * device.pixelRatio
    ..padding = safeAreas.toFakeViewPadding(
      devicePixelRatio: device.pixelRatio,
    )
    ..devicePixelRatio = device.pixelRatio;

  debugDefaultTargetPlatformOverride = device.identifier.platform;

  return restore;
}