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      1 // Copyright 2015 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 function getStrictF() {
      6   'use strict';
      7   return function f(x) {};
      8 }
      9 
     10 
     11 function getSloppyF() {
     12   return function f(x) {};
     13 }
     14 
     15 
     16 function getStrictGenerator() {
     17   'use strict';
     18   return function* f(x) {};
     19 }
     20 
     21 
     22 function getSloppyGenerator() {
     23   return function* f(x) {};
     24 }
     25 
     26 
     27 function test(testFunction) {
     28   testFunction(getStrictF());
     29   testFunction(getSloppyF());
     30   testFunction(getStrictGenerator());
     31   testFunction(getSloppyGenerator());
     32 }
     33 
     34 
     35 function testDescriptor(f) {
     36   var descr = Object.getOwnPropertyDescriptor(f, 'length');
     37   assertTrue(descr.configurable);
     38   assertFalse(descr.enumerable);
     39   assertEquals(1, descr.value);
     40   assertFalse(descr.writable);
     41 }
     42 test(testDescriptor);
     43 
     44 
     45 function testSet(f) {
     46   f.length = 2;
     47   assertEquals(1, f.length);
     48 }
     49 test(testSet);
     50 
     51 
     52 function testSetStrict(f) {
     53   'use strict';
     54   assertThrows(function() {
     55     f.length = 2;
     56   }, TypeError);
     57 }
     58 test(testSetStrict);
     59 
     60 
     61 function testReconfigureAsDataProperty(f) {
     62   Object.defineProperty(f, 'length', {
     63     value: 2,
     64   });
     65   assertEquals(2, f.length);
     66   Object.defineProperty(f, 'length', {
     67     writable: true
     68   });
     69   f.length = 3;
     70   assertEquals(3, f.length);
     71 
     72   f.length = 42;
     73   assertEquals(42, f.length);
     74 }
     75 test(testReconfigureAsDataProperty);
     76 
     77 
     78 function testReconfigureAsAccessorProperty(f) {
     79   var length = 2;
     80   Object.defineProperty(f, 'length', {
     81     get: function() { return length; },
     82     set: function(v) { length = v; }
     83   });
     84   assertEquals(2, f.length);
     85   f.length = 3;
     86   assertEquals(3, f.length);
     87 }
     88 test(testReconfigureAsAccessorProperty);
     89 
     90 
     91 (function testSetOnInstance() {
     92   // This needs to come before testDelete below
     93   assertTrue(Function.prototype.hasOwnProperty('length'));
     94 
     95   function f() {}
     96   delete f.length;
     97   assertEquals(0, f.length);
     98 
     99   f.length = 42;
    100   assertEquals(0, f.length);  // non writable prototype property.
    101   assertFalse(f.hasOwnProperty('length'));
    102 
    103   Object.defineProperty(Function.prototype, 'length', {writable: true});
    104 
    105   f.length = 123;
    106   assertTrue(f.hasOwnProperty('length'));
    107   assertEquals(123, f.length);
    108 })();
    109 
    110 
    111 (function testDelete() {
    112   function f(x) {}
    113   assertTrue(delete f.length);
    114   assertFalse(f.hasOwnProperty('length'));
    115   assertEquals(0, f.length);
    116 
    117   assertTrue(delete Function.prototype.length);
    118   assertEquals(undefined, f.length);
    119 })();
    120