LibTest/core/Function/operator_eq_A01_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 ==(Object other)
/// Test whether another object is equal to this function.
/// System-created function objects are only equal to other functions.
/// Two function objects are known to represent the same function if
///  - It is the same object. Static and top-level functions are compile time
///  constants when used as values, so referring to the same function twice
///  always give the same object,
///  - or if they refer to the same member method extracted from the same object.
///  Extracting a member method as a function value twice gives equal, but not
///  necessarily identical, function values.
///  Function expressions never give rise to equal function objects. Each time a
///  function expression is evaluated, it creates a new closure value that is not
///  known to be equal to other closures created by the same expression.
///
///  Classes implementing Function by having a call method should have their own
///  operator== and hashCode depending on the object.
/// @description Checks that equality operator works as expected.
/// @author sgrekhov@unipro.ru
/// @issue 42895

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

class C {
  m() {
  }
}

String foo(x1, y1, {x2 : "x2", y2}) {
  return "$x1$y1$x2$y2";
}

String bar(x1, y1, {x2 : "x2", y2}) {
  return "$x1$y1$x2$y2";
}

main() {
  Function f1 = foo;
  Function f2 = foo;
  Function b1 = bar;
  Function b2 = bar;

  Expect.isTrue(f1 == f2);
  Expect.isTrue(b1 == b2);
  Expect.isFalse(f1 == b1);

  Function m1 = new C().m;
  Function m2 = new C().m;
  Expect.isFalse(m1 == m2);
}