Dart / Flutter Web: How to write a test that covers `kIsWeb == true`?

I want to run a unit test that covers both possible cases, web and non-web deployment. The code for the class to be tested basically looks like this:

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    if (kIsWeb) {
      return Text("I'm web");
    } else {
      return Text("I'm not web");
    }
  }
}

kIsWeb is a constant provided by Dart that determines if the application was compiled to run on the web.

My current test class implementation is only able to test the non-web path. Is there a way to create a test for the case of kIsWeb == true?