// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

/// @assertion In an unmigrated library, override checking is done using legacy
/// types. This means that an unmigrated library can bring together otherwise
/// incompatible methods. When choosing the most specific signature during
/// interface computation, all nullability and requiredness annotations are
/// ignored, and the [Never] type is treated as [Null].
///
/// @description Check that if legacy class extends legacy class and implements
/// opted-in class, legacy method can return [null] if parent method return type
/// is nullable.
///
/// @author iarkh@unipro.ru

// Requirements=nnbd-weak
// @dart=2.6

import "dart:async";
import "../../../../Utils/expect.dart";
import "override_checking_A01_opted_in_lib.dart";

class A extends B implements OPTED_NULLABLE_RETURN {}

class B {
  int      getInt()      => null;
  Object   getObject()   => null;
  Function getFunction() => null;
  FutureOr getFutureOr() => null;
  dynamic  getDynamic()  => null;
  Null     getNull()     => null;
}

main() {
  A a = A();

  Expect.isNull(a.getInt());
  Expect.isNull(a.getObject());
  Expect.isNull(a.getFutureOr());
  Expect.isNull(a.getDynamic());
  Expect.isNull(a.getFunction());
  Expect.isNull(a.getNull());
}