LibTest/core/Object/operator_equality_A03_t01.dart

// Copyright (c) 2016, 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 bool operator ==(other)
/// The equality operator.
///
/// The default behavior for all Objects is to return true if and only if this
/// and other are the same object.
///
/// Override this method to specify a different equality relation on a class.
/// The overriding method must still be an equivalence relation. That is, it must
/// be:
/// ...
/// Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both
/// be true, or both be false.
/// ...
/// @description Checks that for all objects o1 and o2, o1 == o2 and o2 == o1 is
/// either both true, or both false.
/// @author sgrekhov@unipro.ru

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

main() {
  const o1 = const Object();
  Object o2 = new Object();
  Object o3 = new Object();
  var o4 = o3;

  Expect.isFalse(o1 == o2);
  Expect.isFalse(o2 == o1);
  Expect.isFalse(o2 == o3);
  Expect.isFalse(o3 == o2);

  Expect.isTrue(o3 == o4);
  Expect.isTrue(o4 == o3);
}