cyclic-stringify.js

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// Any copyright is dedicated to the Public Domain.

// http://creativecommons.org/licenses/publicdomain/

//-----------------------------------------------------------------------------

var BUGNUMBER = 578273;

var summary =

  "ES5: Properly detect cycles in JSON.stringify (throw TypeError, check for " +

  "cycles rather than imprecisely rely on recursion limits)";

print(BUGNUMBER + ": " + summary);

/**************

 * BEGIN TEST *

 **************/

// objects

var count = 0;

var desc =

    get: function() { count++; return obj; },

    enumerable: true,

    configurable: true

};

var obj = Object.defineProperty({ p1: 0 }, "p2", desc);

try

  var str = JSON.stringify(obj);

  assertEq(false, true, "should have thrown, got " + str);

catch (e)

  assertEq(e instanceof TypeError, true,

           "wrong error type: " + e.constructor.name);

  assertEq(count, 1,

           "cyclic data structures not detected immediately");

count = 0;

var obj2 = Object.defineProperty({}, "obj", desc);

try

  var str = JSON.stringify(obj2);

  assertEq(false, true, "should have thrown, got " + str);

catch (e)

  assertEq(e instanceof TypeError, true,

           "wrong error type: " + e.constructor.name);

  assertEq(count, 2,

           "cyclic data structures not detected immediately");

// arrays

var count = 0;

var desc =

    get: function() { count++; return arr; },

    enumerable: true,

    configurable: true

};

var arr = Object.defineProperty([], "0", desc);

try

  var str = JSON.stringify(arr);

  assertEq(false, true, "should have thrown, got " + str);

catch (e)

  assertEq(e instanceof TypeError, true,

           "wrong error type: " + e.constructor.name);

  assertEq(count, 1,

           "cyclic data structures not detected immediately");

count = 0;

var arr2 = Object.defineProperty([], "0", desc);

try

  var str = JSON.stringify(arr2);

  assertEq(false, true, "should have thrown, got " + str);

catch (e)

  assertEq(e instanceof TypeError, true,

           "wrong error type: " + e.constructor.name);

  assertEq(count, 2,

           "cyclic data structures not detected immediately");

/******************************************************************************/

if (typeof reportCompare === "function")

  reportCompare(true, true);

print("Tests complete");