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/**
* Tests util.getPropertyDescriptor
*
* Copyright (C) 2011, 2013 Mike Gerwitz
*
* This file is part of GNU ease.js.
*
* ease.js is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
var common = require( './common' ),
assert = require( 'assert' ),
util = common.require( 'util' ),
get_set = !( util.definePropertyFallback() )
;
/**
* If Object.getOwnPropertyDescriptor is provided by our environment, it should
* be used by util
*/
( function testUtilGetOwnPropertyDescriptorIsObjectsIfAvailable()
{
if ( get_set && Object.getOwnPropertyDescriptor )
{
assert.strictEqual(
util.getOwnPropertyDescriptor,
Object.getOwnPropertyDescriptor,
"Util should use Object.getOwnPropertyDescriptor if available"
);
}
} )();
/**
* The function should provide a boolean value indicating whether it can
* traverse the prototype chain
*/
( function testIndicatesWhetherTraversalIsPossible()
{
var traversable = ( {}.__proto__ ) ? true : false;
assert.equal( util.getPropertyDescriptor.canTraverse, traversable,
"Indicates whether traversal is possible"
);
} )();
/**
* We don't want tricksters to get funky with our system
*/
( function testTraversablePropertyIsNonWritable()
{
var getDesc;
if ( get_set )
{
assert.equal(
Object.getOwnPropertyDescriptor(
util.getPropertyDescriptor, 'canTraverse'
).writable,
false,
"Should not be able to alter canTravese value"
);
}
} )();
/**
* The return value should mimic Object.getOwnPropertyDescriptor() if we're not
* having to traverse the prototype chain
*/
( function testActsExactlyAsGetOwnPropertyDescriptorInEs5SystemsOnSameObject()
{
var obj = { foo: 'bar' },
desc1 = util.getOwnPropertyDescriptor( obj, 'foo' ),
desc2 = util.getPropertyDescriptor( obj, 'foo' )
;
assert.deepEqual( desc1, desc2,
"When operating one level deep, should return same as " +
"Object.getOwnPropertyDescriptor"
);
} )();
/**
* If we *do* have to start traversing the prototype chain (which
* Object.getOwnPropertyDescriptor() cannot do), then it should be as if we
* called Object.getOwnPropertyDescriptor() on the object in the prototype chain
* containing the requested property.
*/
( function testTraversesThePrototypeChain()
{
// if we cannot traverse the prototype chain, this test is pointless
if ( !util.getPropertyDescriptor.canTraverse )
{
return;
}
var proto = { foo: 'bar' },
obj = function() {}
;
obj.prototype = proto;
// to give ourselves the prototype chain (we don't want to set __proto__
// because this test will also be run on pre-ES5 engines)
var inst = new obj(),
// get the actual descriptor
expected = util.getOwnPropertyDescriptor( proto, 'foo' ),
// attempt to gather the descriptor from the prototype chain
given = util.getPropertyDescriptor( inst, 'foo' )
;
assert.deepEqual( given, expected,
"Properly traverses the prototype chain to retrieve the descriptor"
);
} )();