test/webkit/cyclic-prototypes.js

// Copyright 2013 the V8 project authors. All rights reserved.
// Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1.  Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
// 2.  Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in the
//     documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
// ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

description("This test makes sure we don't hang when setting cyclic prototype values: http://bugs.webkit.org/show_bug.cgi?id=6985")

var o1 = { p1: 1 };
var o2 = { p2: 2 };
o2.__proto__ = o1;
var o3 = { p3: 3 };
o3.__proto__ = o2;

// Try to create a cyclical prototype chain.
shouldThrow("o1.__proto__ = o3;");

// This changes behaviour, since __proto__ is an accessor on Object.prototype.
o1.__proto__ = null;

shouldBeFalse("({}).hasOwnProperty.call(o1, '__proto__')");
o1.__proto__ = o3;
shouldBeTrue("({}).hasOwnProperty.call(o1, '__proto__')");
shouldBe("Object.getPrototypeOf(o1)", "null");