Simulate Android in integration tests

Question

I'm coding automatic screenshots for my app using Flutter's integration_test + golden tests.

When I run flutter run I usually press o a couple of times. It changes look of my app. With this I can select Android UI emulation, and my app looks like Android app (with fonts and spacing like on Android app) even though I run my app on Linux without any emulator.

The problem I'm facing is: I want my golden files to look like on they have been taken on Android device. Is there a way to do that like in example below?

This is the difference between not simulating (1 picture), and simulating Android (2 picture):

I did not found any documentation on this problem, sadly.

Answer 1

I found solution.

You just need to insert this line at the start of each of your tests:

debugDefaultTargetPlatformOverride = TargetPlatform.android;

And, at the end of the tests:

debugDefaultTargetPlatformOverride = null;

Last line needed in order to avoid this error: The value of a foundation debug variable was changed by the test.

My screenshot function now looks like this:

void makeScreenshot(
    Widget w, String testName, String fileName, Function(WidgetTester) later) {
  testWidgets(testName, (WidgetTester tester) async {
    tester.view.physicalSize = const Size(1080 / 2, 1920 / 2);
    debugDefaultTargetPlatformOverride = TargetPlatform.android;

    await tester.pumpWidget(w);

    // Without this line the whole method does not work.
    // main.png is just a blank screenshot.
    await tester.pumpAndSettle();

    await later(tester);

    await expectLater(
      find.byType(SudokuApp),
      matchesGoldenFile('screenshots/$fileName.png'),
    );
    debugDefaultTargetPlatformOverride = null;
  });
}