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27
28// Tests the Object.preventExtensions method - ES 15.2.3.10
29
30// Flags: --allow-natives-syntax
31
32
33var obj1 = {};
34// Extensible defaults to true.
35assertTrue(Object.isExtensible(obj1));
36Object.preventExtensions(obj1);
37
38// Make sure the is_extensible flag is set.
39assertFalse(Object.isExtensible(obj1));
40obj1.x = 42;
41assertEquals(undefined, obj1.x);
42
43// Try adding a new element.
44obj1[1] = 42;
45assertEquals(undefined, obj1[1]);
46
47
48// Try when the object has an existing property.
49var obj2 = {};
50assertTrue(Object.isExtensible(obj2));
51obj2.x = 42;
52assertEquals(42, obj2.x);
53assertTrue(Object.isExtensible(obj2));
54
55Object.preventExtensions(obj2);
56assertEquals(42, obj2.x);
57
58obj2.y = 42;
59// obj2.y should still be undefined.
60assertEquals(undefined, obj2.y);
61// Make sure we can still write values to obj.x.
62obj2.x = 43;
63assertEquals(43, obj2.x)
64
65obj2.y = new function() { return 42; };
66// obj2.y should still be undefined.
67assertEquals(undefined, obj2.y);
68assertEquals(43, obj2.x)
69
70try {
71  Object.defineProperty(obj2, "y", {value: 42});
72} catch (e) {
73  assertTrue(/object is not extensible/.test(e));
74}
75
76// obj2.y should still be undefined.
77assertEquals(undefined, obj2.y);
78assertEquals(43, obj2.x);
79
80obj2[1] = 42;
81assertEquals(undefined, obj2[1]);
82
83var arr = new Array();
84arr[1] = 10;
85
86Object.preventExtensions(arr);
87
88arr[2] = 42;
89assertEquals(10, arr[1]);
90
91// We should still be able to change existing elements.
92arr[1]= 42;
93assertEquals(42, arr[1]);
94
95
96// Test the the extensible flag is not inherited.
97var parent = {};
98parent.x = 42;
99Object.preventExtensions(parent);
100
101var child = Object.create(parent);
102
103// We should be able to add new properties to the child object.
104child.y = 42;
105
106// This should have no influence on the parent class.
107parent.y = 29;
108
109
110// Test that attributes on functions are also handled correctly.
111function foo() {
112  return 42;
113}
114
115Object.preventExtensions(foo);
116
117foo.x = 29;
118assertEquals(undefined, foo.x);
119
120// when Object.isExtensible(o) === false
121// assignment should return right hand side value
122var o = Object.preventExtensions({});
123var v = o.v = 50;
124assertEquals(undefined, o.v);
125assertEquals(50, v);
126
127// test same behavior as above, but for integer properties
128var n = o[0] = 100;
129assertEquals(undefined, o[0]);
130assertEquals(100, n);
131
132// Fast properties should remain fast
133obj = { x: 42, y: 'foo' };
134assertTrue(%HasFastProperties(obj));
135Object.preventExtensions(obj);
136assertFalse(Object.isExtensible(obj));
137assertFalse(Object.isSealed(obj));
138assertTrue(%HasFastProperties(obj));
139
140// Non-extensible objects should share maps where possible
141obj = { prop1: 1, prop2: 2 };
142obj2 = { prop1: 3, prop2: 4 };
143assertTrue(%HaveSameMap(obj, obj2));
144Object.preventExtensions(obj);
145Object.preventExtensions(obj2);
146assertFalse(Object.isExtensible(obj));
147assertFalse(Object.isExtensible(obj2));
148assertFalse(Object.isSealed(obj));
149assertFalse(Object.isSealed(obj2));
150assertTrue(%HaveSameMap(obj, obj2));
151
152// Non-extensible objects should share maps even when they have elements
153obj = { prop1: 1, prop2: 2, 75: 'foo' };
154obj2 = { prop1: 3, prop2: 4, 150: 'bar' };
155assertTrue(%HaveSameMap(obj, obj2));
156Object.preventExtensions(obj);
157Object.preventExtensions(obj2);
158assertFalse(Object.isExtensible(obj));
159assertFalse(Object.isExtensible(obj2));
160assertFalse(Object.isSealed(obj));
161assertFalse(Object.isSealed(obj2));
162assertTrue(%HaveSameMap(obj, obj2));
163