tests/language/generic_methods/optional_parameters_test.dart

// Copyright (c) 2017, 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.

// Test that generic methods with optional parameters are of correct type.

library generic_methods_optional_parameters_test;

import "package:expect/expect.dart";

typedef FunObjObj = Object? Function<T>(Object?, [Object?]);
typedef FunTypObj = Object? Function<T>(T, [Object?]);
typedef FunObjTyp = Object? Function<T>(Object?, [T?]);
typedef FunTypTyp = Object? Function<T>(T, [T?]);

Object? funObjObj<T>(Object? x, [Object? y]) => x;
Object? funTypObj<T>(T x, [Object? y]) => y;
Object? funObjTyp<T>(Object? x, [T? y]) => x;
Object? funTypTyp<T>(T x, [T? y]) => null;

main() {
  Expect.isTrue(funObjObj is FunObjObj);
  Expect.isTrue(funObjObj is FunTypObj);
  Expect.isTrue(funObjObj is FunObjTyp);
  Expect.isTrue(funObjObj is FunTypTyp);

  Expect.isTrue(funTypObj is! FunObjObj);
  Expect.isTrue(funTypObj is FunTypObj);
  Expect.isTrue(funTypObj is! FunObjTyp);
  Expect.isTrue(funTypObj is FunTypTyp);

  Expect.isTrue(funObjTyp is! FunObjObj);
  Expect.isTrue(funObjTyp is! FunTypObj);
  Expect.isTrue(funObjTyp is FunObjTyp);
  Expect.isTrue(funObjTyp is FunTypTyp);

  Expect.isTrue(funTypTyp is! FunObjObj);
  Expect.isTrue(funTypTyp is! FunTypObj);
  Expect.isTrue(funTypTyp is! FunObjTyp);
  Expect.isTrue(funTypTyp is FunTypTyp);
}