// Copyright 2010 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * 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. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT // OWNER OR 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. // Tests the object.defineProperty method - ES 15.2.3.6 // Flags: --allow-natives-syntax // Check that an exception is thrown when null is passed as object. try { Object.defineProperty(null, null, null); assertTrue(false); } catch (e) { assertTrue(/called on non-object/.test(e)); } // Check that an exception is thrown when undefined is passed as object. try { Object.defineProperty(undefined, undefined, undefined); assertTrue(false); } catch (e) { assertTrue(/called on non-object/.test(e)); } // Check that an exception is thrown when non-object is passed as object. try { Object.defineProperty(0, "foo", undefined); assertTrue(false); } catch (e) { assertTrue(/called on non-object/.test(e)); } // Object. var obj1 = {}; // Values. var val1 = 0; var val2 = 0; var val3 = 0; function setter1() {val1++; } function getter1() {return val1; } function setter2() {val2++; } function getter2() {return val2; } function setter3() {val3++; } function getter3() {return val3; } // Descriptors. var emptyDesc = {}; var accessorConfigurable = { set: setter1, get: getter1, configurable: true }; var accessorNoConfigurable = { set: setter2, get: getter2, configurable: false }; var accessorOnlySet = { set: setter3, configurable: true }; var accessorOnlyGet = { get: getter3, configurable: true }; var accessorDefault = {set: function(){} }; var dataConfigurable = { value: 1000, configurable: true }; var dataNoConfigurable = { value: 2000, configurable: false }; var dataWritable = { value: 3000, writable: true}; // Check that we can't add property with undefined attributes. try { Object.defineProperty(obj1, "foo", undefined); assertTrue(false); } catch (e) { assertTrue(/must be an object/.test(e)); } // Make sure that we can add a property with an empty descriptor and // that it has the default descriptor values. Object.defineProperty(obj1, "foo", emptyDesc); // foo should be undefined as it has no get, set or value assertEquals(undefined, obj1.foo); // We should, however, be able to retrieve the propertydescriptor which should // have all default values (according to 8.6.1). var desc = Object.getOwnPropertyDescriptor(obj1, "foo"); assertFalse(desc.configurable); assertFalse(desc.enumerable); assertFalse(desc.writable); assertEquals(desc.get, undefined); assertEquals(desc.set, undefined); assertEquals(desc.value, undefined); // Make sure that getOwnPropertyDescriptor does not return a descriptor // with default values if called with non existing property (otherwise // the test above is invalid). desc = Object.getOwnPropertyDescriptor(obj1, "bar"); assertEquals(desc, undefined); // Make sure that foo can't be reset (as configurable is false). try { Object.defineProperty(obj1, "foo", accessorConfigurable); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Accessor properties Object.defineProperty(obj1, "bar", accessorConfigurable); desc = Object.getOwnPropertyDescriptor(obj1, "bar"); assertTrue(desc.configurable); assertFalse(desc.enumerable); assertEquals(desc.writable, undefined); assertEquals(desc.get, accessorConfigurable.get); assertEquals(desc.set, accessorConfigurable.set); assertEquals(desc.value, undefined); assertEquals(1, obj1.bar = 1); assertEquals(1, val1); assertEquals(1, obj1.bar = 1); assertEquals(2, val1); assertEquals(2, obj1.bar); // Redefine bar with non configurable test Object.defineProperty(obj1, "bar", accessorNoConfigurable); desc = Object.getOwnPropertyDescriptor(obj1, "bar"); assertFalse(desc.configurable); assertFalse(desc.enumerable); assertEquals(desc.writable, undefined); assertEquals(desc.get, accessorNoConfigurable.get); assertEquals(desc.set, accessorNoConfigurable.set); assertEquals(desc.value, undefined); assertEquals(1, obj1.bar = 1); assertEquals(2, val1); assertEquals(1, val2); assertEquals(1, obj1.bar = 1) assertEquals(2, val1); assertEquals(2, val2); assertEquals(2, obj1.bar); // Try to redefine bar again - should fail as configurable is false. try { Object.defineProperty(obj1, "bar", accessorConfigurable); assertTrue(false); } catch(e) { assertTrue(/Cannot redefine property/.test(e)); } // Try to redefine bar again using the data descriptor - should fail. try { Object.defineProperty(obj1, "bar", dataConfigurable); assertTrue(false); } catch(e) { assertTrue(/Cannot redefine property/.test(e)); } // Redefine using same descriptor - should succeed. Object.defineProperty(obj1, "bar", accessorNoConfigurable); desc = Object.getOwnPropertyDescriptor(obj1, "bar"); assertFalse(desc.configurable); assertFalse(desc.enumerable); assertEquals(desc.writable, undefined); assertEquals(desc.get, accessorNoConfigurable.get); assertEquals(desc.set, accessorNoConfigurable.set); assertEquals(desc.value, undefined); assertEquals(1, obj1.bar = 1); assertEquals(2, val1); assertEquals(3, val2); assertEquals(1, obj1.bar = 1) assertEquals(2, val1); assertEquals(4, val2); assertEquals(4, obj1.bar); // Define an accessor that has only a setter. Object.defineProperty(obj1, "setOnly", accessorOnlySet); desc = Object.getOwnPropertyDescriptor(obj1, "setOnly"); assertTrue(desc.configurable); assertFalse(desc.enumerable); assertEquals(desc.set, accessorOnlySet.set); assertEquals(desc.writable, undefined); assertEquals(desc.value, undefined); assertEquals(desc.get, undefined); assertEquals(1, obj1.setOnly = 1); assertEquals(1, val3); // Add a getter - should not touch the setter. Object.defineProperty(obj1, "setOnly", accessorOnlyGet); desc = Object.getOwnPropertyDescriptor(obj1, "setOnly"); assertTrue(desc.configurable); assertFalse(desc.enumerable); assertEquals(desc.get, accessorOnlyGet.get); assertEquals(desc.set, accessorOnlySet.set); assertEquals(desc.writable, undefined); assertEquals(desc.value, undefined); assertEquals(1, obj1.setOnly = 1); assertEquals(2, val3); // The above should also work if redefining just a getter or setter on // an existing property with both a getter and a setter. Object.defineProperty(obj1, "both", accessorConfigurable); Object.defineProperty(obj1, "both", accessorOnlySet); desc = Object.getOwnPropertyDescriptor(obj1, "both"); assertTrue(desc.configurable); assertFalse(desc.enumerable); assertEquals(desc.set, accessorOnlySet.set); assertEquals(desc.get, accessorConfigurable.get); assertEquals(desc.writable, undefined); assertEquals(desc.value, undefined); assertEquals(1, obj1.both = 1); assertEquals(3, val3); // Data properties Object.defineProperty(obj1, "foobar", dataConfigurable); desc = Object.getOwnPropertyDescriptor(obj1, "foobar"); assertEquals(obj1.foobar, 1000); assertEquals(desc.value, 1000); assertTrue(desc.configurable); assertFalse(desc.writable); assertFalse(desc.enumerable); assertEquals(desc.get, undefined); assertEquals(desc.set, undefined); //Try writing to non writable attribute - should remain 1000 obj1.foobar = 1001; assertEquals(obj1.foobar, 1000); // Redefine to writable descriptor - now writing to foobar should be allowed. Object.defineProperty(obj1, "foobar", dataWritable); desc = Object.getOwnPropertyDescriptor(obj1, "foobar"); assertEquals(obj1.foobar, 3000); assertEquals(desc.value, 3000); // Note that since dataWritable does not define configurable the configurable // setting from the redefined property (in this case true) is used. assertTrue(desc.configurable); assertTrue(desc.writable); assertFalse(desc.enumerable); assertEquals(desc.get, undefined); assertEquals(desc.set, undefined); // Writing to the property should now be allowed obj1.foobar = 1001; assertEquals(obj1.foobar, 1001); // Redefine with non configurable data property. Object.defineProperty(obj1, "foobar", dataNoConfigurable); desc = Object.getOwnPropertyDescriptor(obj1, "foobar"); assertEquals(obj1.foobar, 2000); assertEquals(desc.value, 2000); assertFalse(desc.configurable); assertTrue(desc.writable); assertFalse(desc.enumerable); assertEquals(desc.get, undefined); assertEquals(desc.set, undefined); // Try redefine again - shold fail because configurable is now false. try { Object.defineProperty(obj1, "foobar", dataConfigurable); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Try redefine again with accessor property - shold also fail. try { Object.defineProperty(obj1, "foobar", dataConfigurable); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Redifine with the same descriptor - should succeed (step 6). Object.defineProperty(obj1, "foobar", dataNoConfigurable); desc = Object.getOwnPropertyDescriptor(obj1, "foobar"); assertEquals(obj1.foobar, 2000); assertEquals(desc.value, 2000); assertFalse(desc.configurable); assertTrue(desc.writable); assertFalse(desc.enumerable); assertEquals(desc.get, undefined); assertEquals(desc.set, undefined); // New object var obj2 = {}; // Make accessor - redefine to data Object.defineProperty(obj2, "foo", accessorConfigurable); // Redefine to data property Object.defineProperty(obj2, "foo", dataConfigurable); desc = Object.getOwnPropertyDescriptor(obj2, "foo"); assertEquals(obj2.foo, 1000); assertEquals(desc.value, 1000); assertTrue(desc.configurable); assertFalse(desc.writable); assertFalse(desc.enumerable); assertEquals(desc.get, undefined); assertEquals(desc.set, undefined); // Redefine back to accessor Object.defineProperty(obj2, "foo", accessorConfigurable); desc = Object.getOwnPropertyDescriptor(obj2, "foo"); assertTrue(desc.configurable); assertFalse(desc.enumerable); assertEquals(desc.writable, undefined); assertEquals(desc.get, accessorConfigurable.get); assertEquals(desc.set, accessorConfigurable.set); assertEquals(desc.value, undefined); assertEquals(1, obj2.foo = 1); assertEquals(3, val1); assertEquals(4, val2); assertEquals(3, obj2.foo); // Make data - redefine to accessor Object.defineProperty(obj2, "bar", dataConfigurable) // Redefine to accessor property Object.defineProperty(obj2, "bar", accessorConfigurable); desc = Object.getOwnPropertyDescriptor(obj2, "bar"); assertTrue(desc.configurable); assertFalse(desc.enumerable); assertEquals(desc.writable, undefined); assertEquals(desc.get, accessorConfigurable.get); assertEquals(desc.set, accessorConfigurable.set); assertEquals(desc.value, undefined); assertEquals(1, obj2.bar = 1); assertEquals(4, val1); assertEquals(4, val2); assertEquals(4, obj2.foo); // Redefine back to data property Object.defineProperty(obj2, "bar", dataConfigurable); desc = Object.getOwnPropertyDescriptor(obj2, "bar"); assertEquals(obj2.bar, 1000); assertEquals(desc.value, 1000); assertTrue(desc.configurable); assertFalse(desc.writable); assertFalse(desc.enumerable); assertEquals(desc.get, undefined); assertEquals(desc.set, undefined); // Redefinition of an accessor defined using __defineGetter__ and // __defineSetter__. function get(){return this.x} function set(x){this.x=x}; var obj3 = {x:1000}; obj3.__defineGetter__("foo", get); obj3.__defineSetter__("foo", set); desc = Object.getOwnPropertyDescriptor(obj3, "foo"); assertTrue(desc.configurable); assertTrue(desc.enumerable); assertEquals(desc.writable, undefined); assertEquals(desc.get, get); assertEquals(desc.set, set); assertEquals(desc.value, undefined); assertEquals(1, obj3.foo = 1); assertEquals(1, obj3.x); assertEquals(1, obj3.foo); // Redefine to accessor property (non configurable) - note that enumerable // which we do not redefine should remain the same (true). Object.defineProperty(obj3, "foo", accessorNoConfigurable); desc = Object.getOwnPropertyDescriptor(obj3, "foo"); assertFalse(desc.configurable); assertTrue(desc.enumerable); assertEquals(desc.writable, undefined); assertEquals(desc.get, accessorNoConfigurable.get); assertEquals(desc.set, accessorNoConfigurable.set); assertEquals(desc.value, undefined); assertEquals(1, obj3.foo = 1); assertEquals(5, val2); assertEquals(5, obj3.foo); obj3.__defineGetter__("bar", get); obj3.__defineSetter__("bar", set); // Redefine back to data property Object.defineProperty(obj3, "bar", dataConfigurable); desc = Object.getOwnPropertyDescriptor(obj3, "bar"); assertEquals(obj3.bar, 1000); assertEquals(desc.value, 1000); assertTrue(desc.configurable); assertFalse(desc.writable); assertTrue(desc.enumerable); assertEquals(desc.get, undefined); assertEquals(desc.set, undefined); var obj4 = {}; var func = function (){return 42;}; obj4.bar = func; assertEquals(42, obj4.bar()); Object.defineProperty(obj4, "bar", accessorConfigurable); desc = Object.getOwnPropertyDescriptor(obj4, "bar"); assertTrue(desc.configurable); assertTrue(desc.enumerable); assertEquals(desc.writable, undefined); assertEquals(desc.get, accessorConfigurable.get); assertEquals(desc.set, accessorConfigurable.set); assertEquals(desc.value, undefined); assertEquals(1, obj4.bar = 1); assertEquals(5, val1); assertEquals(5, obj4.bar); // Make sure an error is thrown when trying to access to redefined function. try { obj4.bar(); assertTrue(false); } catch (e) { assertTrue(/is not a function/.test(e)); } // Test runtime calls to DefineOrRedefineDataProperty and // DefineOrRedefineAccessorProperty - make sure we don't // crash. try { %DefineOrRedefineAccessorProperty(0, 0, 0, 0, 0); } catch (e) { assertTrue(/illegal access/.test(e)); } try { %DefineOrRedefineDataProperty(0, 0, 0, 0); } catch (e) { assertTrue(/illegal access/.test(e)); } try { %DefineOrRedefineDataProperty(null, null, null, null); } catch (e) { assertTrue(/illegal access/.test(e)); } try { %DefineOrRedefineAccessorProperty(null, null, null, null, null); } catch (e) { assertTrue(/illegal access/.test(e)); } try { %DefineOrRedefineDataProperty({}, null, null, null); } catch (e) { assertTrue(/illegal access/.test(e)); } // Defining properties null should fail even when we have // other allowed values try { %DefineOrRedefineAccessorProperty(null, 'foo', 0, func, 0); } catch (e) { assertTrue(/illegal access/.test(e)); } try { %DefineOrRedefineDataProperty(null, 'foo', 0, 0); } catch (e) { assertTrue(/illegal access/.test(e)); } // Test that all possible differences in step 6 in DefineOwnProperty are // exercised, i.e., any difference in the given property descriptor and the // existing properties should not return true, but throw an error if the // existing configurable property is false. var obj5 = {}; // Enumerable will default to false. Object.defineProperty(obj5, 'foo', accessorNoConfigurable); desc = Object.getOwnPropertyDescriptor(obj5, 'foo'); // First, test that we are actually allowed to set the accessor if all // values are of the descriptor are the same as the existing one. Object.defineProperty(obj5, 'foo', accessorNoConfigurable); // Different setter. var descDifferent = { configurable:false, enumerable:false, set: setter1, get: getter2 }; try { Object.defineProperty(obj5, 'foo', descDifferent); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Different getter. descDifferent = { configurable:false, enumerable:false, set: setter2, get: getter1 }; try { Object.defineProperty(obj5, 'foo', descDifferent); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Different enumerable. descDifferent = { configurable:false, enumerable:true, set: setter2, get: getter2 }; try { Object.defineProperty(obj5, 'foo', descDifferent); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Different configurable. descDifferent = { configurable:false, enumerable:true, set: setter2, get: getter2 }; try { Object.defineProperty(obj5, 'foo', descDifferent); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // No difference. descDifferent = { configurable:false, enumerable:false, set: setter2, get: getter2 }; // Make sure we can still redefine if all properties are the same. Object.defineProperty(obj5, 'foo', descDifferent); // Make sure that obj5 still holds the original values. desc = Object.getOwnPropertyDescriptor(obj5, 'foo'); assertEquals(desc.get, getter2); assertEquals(desc.set, setter2); assertFalse(desc.enumerable); assertFalse(desc.configurable); // Also exercise step 6 on data property, writable and enumerable // defaults to false. Object.defineProperty(obj5, 'bar', dataNoConfigurable); // Test that redefinition with the same property descriptor is possible Object.defineProperty(obj5, 'bar', dataNoConfigurable); // Different value. descDifferent = { configurable:false, enumerable:false, writable: false, value: 1999 }; try { Object.defineProperty(obj5, 'bar', descDifferent); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Different writable. descDifferent = { configurable:false, enumerable:false, writable: true, value: 2000 }; try { Object.defineProperty(obj5, 'bar', descDifferent); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Different enumerable. descDifferent = { configurable:false, enumerable:true , writable:false, value: 2000 }; try { Object.defineProperty(obj5, 'bar', descDifferent); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // Different configurable. descDifferent = { configurable:true, enumerable:false, writable:false, value: 2000 }; try { Object.defineProperty(obj5, 'bar', descDifferent); assertTrue(false); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } // No difference. descDifferent = { configurable:false, enumerable:false, writable:false, value:2000 }; // Make sure we can still redefine if all properties are the same. Object.defineProperty(obj5, 'bar', descDifferent); // Make sure that obj5 still holds the original values. desc = Object.getOwnPropertyDescriptor(obj5, 'bar'); assertEquals(desc.value, 2000); assertFalse(desc.writable); assertFalse(desc.enumerable); assertFalse(desc.configurable); // Make sure that we can't overwrite +0 with -0 and vice versa. var descMinusZero = {value: -0, configurable: false}; var descPlusZero = {value: +0, configurable: false}; Object.defineProperty(obj5, 'minuszero', descMinusZero); // Make sure we can redefine with -0. Object.defineProperty(obj5, 'minuszero', descMinusZero); try { Object.defineProperty(obj5, 'minuszero', descPlusZero); assertUnreachable(); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } Object.defineProperty(obj5, 'pluszero', descPlusZero); // Make sure we can redefine with +0. Object.defineProperty(obj5, 'pluszero', descPlusZero); try { Object.defineProperty(obj5, 'pluszero', descMinusZero); assertUnreachable(); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } var obj6 = {}; obj6[1] = 'foo'; obj6[2] = 'bar'; obj6[3] = '42'; obj6[4] = '43'; obj6[5] = '44'; var descElement = { value: 'foobar' }; var descElementNonConfigurable = { value: 'barfoo', configurable: false }; var descElementNonWritable = { value: 'foofoo', writable: false }; var descElementNonEnumerable = { value: 'barbar', enumerable: false }; var descElementAllFalse = { value: 'foofalse', configurable: false, writable: false, enumerable: false }; // Redefine existing property. Object.defineProperty(obj6, '1', descElement); desc = Object.getOwnPropertyDescriptor(obj6, '1'); assertEquals(desc.value, 'foobar'); assertTrue(desc.writable); assertTrue(desc.enumerable); assertTrue(desc.configurable); // Redefine existing property with configurable: false. Object.defineProperty(obj6, '2', descElementNonConfigurable); desc = Object.getOwnPropertyDescriptor(obj6, '2'); assertEquals(desc.value, 'barfoo'); assertTrue(desc.writable); assertTrue(desc.enumerable); assertFalse(desc.configurable); // Ensure that we can't overwrite the non configurable element. try { Object.defineProperty(obj6, '2', descElement); assertUnreachable(); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } Object.defineProperty(obj6, '3', descElementNonWritable); desc = Object.getOwnPropertyDescriptor(obj6, '3'); assertEquals(desc.value, 'foofoo'); assertFalse(desc.writable); assertTrue(desc.enumerable); assertTrue(desc.configurable); // Redefine existing property with configurable: false. Object.defineProperty(obj6, '4', descElementNonEnumerable); desc = Object.getOwnPropertyDescriptor(obj6, '4'); assertEquals(desc.value, 'barbar'); assertTrue(desc.writable); assertFalse(desc.enumerable); assertTrue(desc.configurable); // Redefine existing property with configurable: false. Object.defineProperty(obj6, '5', descElementAllFalse); desc = Object.getOwnPropertyDescriptor(obj6, '5'); assertEquals(desc.value, 'foofalse'); assertFalse(desc.writable); assertFalse(desc.enumerable); assertFalse(desc.configurable); // Define non existing property - all attributes should default to false. Object.defineProperty(obj6, '15', descElement); desc = Object.getOwnPropertyDescriptor(obj6, '15'); assertEquals(desc.value, 'foobar'); assertFalse(desc.writable); assertFalse(desc.enumerable); assertFalse(desc.configurable); // Make sure that we can't redefine using direct access. obj6[15] ='overwrite'; assertEquals(obj6[15],'foobar'); // Repeat the above tests on an array. var arr = new Array(); arr[1] = 'foo'; arr[2] = 'bar'; arr[3] = '42'; arr[4] = '43'; arr[5] = '44'; var descElement = { value: 'foobar' }; var descElementNonConfigurable = { value: 'barfoo', configurable: false }; var descElementNonWritable = { value: 'foofoo', writable: false }; var descElementNonEnumerable = { value: 'barbar', enumerable: false }; var descElementAllFalse = { value: 'foofalse', configurable: false, writable: false, enumerable: false }; // Redefine existing property. Object.defineProperty(arr, '1', descElement); desc = Object.getOwnPropertyDescriptor(arr, '1'); assertEquals(desc.value, 'foobar'); assertTrue(desc.writable); assertTrue(desc.enumerable); assertTrue(desc.configurable); // Redefine existing property with configurable: false. Object.defineProperty(arr, '2', descElementNonConfigurable); desc = Object.getOwnPropertyDescriptor(arr, '2'); assertEquals(desc.value, 'barfoo'); assertTrue(desc.writable); assertTrue(desc.enumerable); assertFalse(desc.configurable); // Ensure that we can't overwrite the non configurable element. try { Object.defineProperty(arr, '2', descElement); assertUnreachable(); } catch (e) { assertTrue(/Cannot redefine property/.test(e)); } Object.defineProperty(arr, '3', descElementNonWritable); desc = Object.getOwnPropertyDescriptor(arr, '3'); assertEquals(desc.value, 'foofoo'); assertFalse(desc.writable); assertTrue(desc.enumerable); assertTrue(desc.configurable); // Redefine existing property with configurable: false. Object.defineProperty(arr, '4', descElementNonEnumerable); desc = Object.getOwnPropertyDescriptor(arr, '4'); assertEquals(desc.value, 'barbar'); assertTrue(desc.writable); assertFalse(desc.enumerable); assertTrue(desc.configurable); // Redefine existing property with configurable: false. Object.defineProperty(arr, '5', descElementAllFalse); desc = Object.getOwnPropertyDescriptor(arr, '5'); assertEquals(desc.value, 'foofalse'); assertFalse(desc.writable); assertFalse(desc.enumerable); assertFalse(desc.configurable); // Define non existing property - all attributes should default to false. Object.defineProperty(arr, '15', descElement); desc = Object.getOwnPropertyDescriptor(arr, '15'); assertEquals(desc.value, 'foobar'); assertFalse(desc.writable); assertFalse(desc.enumerable); assertFalse(desc.configurable);