class Class1 {
  Class1._();
  factory Class1() => new Class1._();
}

class Class2 {
  Class2._();
  factory Class2.named() => new Class2._();
}

class Class3 {
  Class3._(this.field);
  factory Class3(int field) => new Class3._(field);
  final int field;
}

class Class4 {
  Class4._([this.field]);
  factory Class4([int? field]) => new Class4._(field);
  final int? field;
}

class Class5 {
  Class5._(this.field1, [this.field2]);
  factory Class5(int field1, [int? field2]) => new Class5._(field1, field2);
  final int? field2;
  final int field1;
}

class Class6 {
  Class6._(this.field1, {this.field2, required this.field3});
  factory Class6(int field1, {int? field2, required int field3}) =>
      new Class6._(field1, field2: field2, field3: field3);
  final int? field2;
  final int field1;
  final int field3;
}

expect(expected, actual) {}
final bool inSoundMode = <int?>[] is! List<int>;
main() {}
testArgs() {}
testNoArgs() {}
throws(Function() f, {bool inSoundModeOnly: false}) {}