src/v8/test/webkit/dictionary-prototype-caching.js

// Copyright 2013 the V8 project authors. All rights reserved.
// Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
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description("Test to ensure correct behaviour of prototype caching with dictionary prototypes");

function protoTest(o) {
    return o.protoProp;
}

var proto = {protoProp: "PASS", propToRemove: "foo"};
var o = { __proto__: proto };

delete proto.propToRemove;

// Prototype lookup caching will attempt to convert proto back to an ordinary structure
protoTest(o);
protoTest(o);
protoTest(o);
shouldBe("protoTest(o)", "'PASS'");
delete proto.protoProp;
proto.fakeProtoProp = "FAIL";
shouldBeUndefined("protoTest(o)");

function protoTest2(o) {
    return o.b;
}

var proto = {a:1, b:"meh", c:2};
var o = { __proto__: proto };

delete proto.b;
proto.d = 3;
protoTest2(o);
protoTest2(o);
protoTest2(o);
var protoKeys = [];
for (var i in proto)
    protoKeys.push(proto[i]);

shouldBe("protoKeys", "[1,2,3]");

function protoTest3(o) {
    return o.b;
}

var proto = {a:1, b:"meh", c:2};
var o = { __proto__: proto };

delete proto.b;
protoTest2(o);
protoTest2(o);
protoTest2(o);
proto.d = 3;
var protoKeys = [];
for (var i in proto)
    protoKeys.push(proto[i]);

shouldBe("protoKeys", "[1,2,3]");

function testFunction(o) {
    return o.test;
}

var proto = { test: true };
var subclass1 = { __proto__: proto };
var subclass2 = { __proto__: proto };
for (var i = 0; i < 500; i++)
    subclass2["a"+i]="a"+i;

testFunction(subclass1);
shouldBeTrue("testFunction(subclass1)");
shouldBeTrue("testFunction(subclass2)");
proto.test = false
subclass2.test = true;
shouldBeTrue("testFunction(subclass2)");