final bool inSoundMode = <int?>[] is! List<int>;
main() {}

class Class1 {
  final int field;
  Class1._(this.field);
  factory Class1([int field = 42]) => new Class1._(field);
}

class Class2 {
  final int field;
  Class2._(this.field);
  factory Class2({int field: 42}) => new Class2._(field);
}

void testDefaultValues() {}
expect(expected, actual) {}
throws(Function() f, {bool inSoundModeOnly: false}) {}