object-prevent-extensions.js revision 8defd9ff6930b4e24729971a61cf7469daf119be 
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27
28// Tests the Object.preventExtensions method - ES 15.2.3.10
29
30
31var obj1 = {};
32// Extensible defaults to true.
33assertTrue(Object.isExtensible(obj1));
34Object.preventExtensions(obj1);
35
36// Make sure the is_extensible flag is set.
37assertFalse(Object.isExtensible(obj1));
38// Try adding a new property.
39try {
40  obj1.x = 42;
41  assertUnreachable();
42} catch (e) {
43  assertTrue(/object is not extensible/.test(e));
44}
45assertEquals(undefined, obj1.x);
46
47// Try adding a new element.
48try {
49  obj1[1] = 42;
50  assertUnreachable();
51} catch (e) {
52  assertTrue(/object is not extensible/.test(e));
53}
54assertEquals(undefined, obj1[1]);
55
56
57// Try when the object has an existing property.
58var obj2 = {};
59assertTrue(Object.isExtensible(obj2));
60obj2.x = 42;
61assertEquals(42, obj2.x);
62assertTrue(Object.isExtensible(obj2));
63
64Object.preventExtensions(obj2);
65assertEquals(42, obj2.x);
66
67try {
68  obj2.y = 42;
69  assertUnreachable();
70} catch (e) {
71  assertTrue(/object is not extensible/.test(e));
72}
73
74// obj2.y should still be undefined.
75assertEquals(undefined, obj2.y);
76// Make sure we can still write values to obj.x.
77obj2.x = 43;
78assertEquals(43, obj2.x)
79
80try {
81  obj2.y = new function() { return 42; };
82  assertUnreachable();
83} catch (e) {
84  assertTrue(/object is not extensible/.test(e));
85}
86// obj2.y should still be undefined.
87assertEquals(undefined, obj2.y);
88assertEquals(43, obj2.x)
89
90try {
91  Object.defineProperty(obj2, "y", {value: 42});
92} catch (e) {
93  assertTrue(/object is not extensible/.test(e));
94}
95
96// obj2.y should still be undefined.
97assertEquals(undefined, obj2.y);
98assertEquals(43, obj2.x);
99
100try {
101  obj2[1] = 42;
102} catch (e) {
103  assertTrue(/object is not extensible/.test(e));
104}
105
106assertEquals(undefined, obj2[1]);
107
108var arr = new Array();
109arr[1] = 10;
110
111Object.preventExtensions(arr);
112
113try {
114  arr[2] = 42;
115  assertUnreachable();
116} catch (e) {
117  assertTrue(/object is not extensible/.test(e));
118}
119assertEquals(10, arr[1]);
120
121// We should still be able to change exiting elements.
122arr[1]= 42;
123assertEquals(42, arr[1]);
124
125
126// Test the the extensible flag is not inherited.
127var parent = {};
128parent.x = 42;
129Object.preventExtensions(parent);
130
131var child = Object.create(parent);
132
133// We should be able to add new properties to the child object.
134child.y = 42;
135
136// This should have no influence on the parent class.
137try {
138  parent.y = 29;
139  assertUnreachable();
140} catch (e) {
141  assertTrue(/object is not extensible/.test(e));
142}
143
144
145// Test that attributes on functions are also handled correctly.
146function foo() {
147  return 42;
148}
149
150Object.preventExtensions(foo);
151
152try {
153  foo.x = 29;
154  assertUnreachable();
155} catch (e) {
156  assertTrue(/object is not extensible/.test(e));
157}
158