Language/Classes/Superclasses/transition_t02.dart

// Copyright (c) 2019, 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 A class S is a superclass of a class C iff either:
/// - S is the superclass of C, or
/// - S is a superclass of a class S0 and S0 is a superclass of C.
/// @description Checks that the superclass-subclass relationship is transitive.
/// Test type aliases
/// @author sgrekhov@unipro.ru

import "../../../Utils/expect.dart";

class A {}
typedef AAlias = A;
class B extends AAlias {}
typedef BAlias = B;
class C extends BAlias {}
typedef CAlias = C;
class D extends CAlias {}

main() {
  D d = new D();
  Expect.isTrue(d is C);
  Expect.isTrue(d is B);
  Expect.isTrue(d is A);
}