1// Copyright 2011 the V8 project authors. All rights reserved.
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3// modification, are permitted provided that the following conditions are
4// met:
5//
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8//     * Redistributions in binary form must reproduce the above
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11//       with the distribution.
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13//       contributors may be used to endorse or promote products derived
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15//
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17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28// Test that redefining the 'prototype' property of a function object
29// does actually set the internal value and does not screw up any
30// shadowing between said property and the internal value.
31
32var f = function() {};
33
34// Verify that normal assignment of 'prototype' property works properly
35// and updates the internal value.
36var a = { foo: 'bar' };
37f.prototype = a;
38assertSame(f.prototype, a);
39assertSame(f.prototype.foo, 'bar');
40assertSame(new f().foo, 'bar');
41assertSame(Object.getPrototypeOf(new f()), a);
42assertSame(Object.getOwnPropertyDescriptor(f, 'prototype').value, a);
43assertTrue(Object.getOwnPropertyDescriptor(f, 'prototype').writable);
44
45// Verify that 'prototype' behaves like a data property when it comes to
46// redefining with Object.defineProperty() and the internal value gets
47// updated.
48var b = { foo: 'baz' };
49Object.defineProperty(f, 'prototype', { value: b, writable: true });
50assertSame(f.prototype, b);
51assertSame(f.prototype.foo, 'baz');
52assertSame(new f().foo, 'baz');
53assertSame(Object.getPrototypeOf(new f()), b);
54assertSame(Object.getOwnPropertyDescriptor(f, 'prototype').value, b);
55assertTrue(Object.getOwnPropertyDescriptor(f, 'prototype').writable);
56
57// Verify that the previous redefinition didn't screw up callbacks and
58// the internal value still gets updated.
59var c = { foo: 'other' };
60f.prototype = c;
61assertSame(f.prototype, c);
62assertSame(f.prototype.foo, 'other');
63assertSame(new f().foo, 'other');
64assertSame(Object.getPrototypeOf(new f()), c);
65assertSame(Object.getOwnPropertyDescriptor(f, 'prototype').value, c);
66assertTrue(Object.getOwnPropertyDescriptor(f, 'prototype').writable);
67
68// Verify that 'prototype' can be redefined to contain a different value
69// and have a different writability attribute at the same time.
70var d = { foo: 'final' };
71Object.defineProperty(f, 'prototype', { value: d, writable: false });
72assertSame(f.prototype, d);
73assertSame(f.prototype.foo, 'final');
74assertSame(new f().foo, 'final');
75assertSame(Object.getPrototypeOf(new f()), d);
76assertSame(Object.getOwnPropertyDescriptor(f, 'prototype').value, d);
77assertFalse(Object.getOwnPropertyDescriptor(f, 'prototype').writable);
78
79// Verify that non-writability of redefined 'prototype' is respected.
80assertThrows("'use strict'; f.prototype = {}");
81assertThrows("Object.defineProperty(f, 'prototype', { value: {} })");
82
83// Verify that non-writability of other properties is respected.
84assertThrows("Object.defineProperty(f, 'name', { value: {} })");
85assertThrows("Object.defineProperty(f, 'length', { value: {} })");
86assertThrows("Object.defineProperty(f, 'caller', { value: {} })");
87assertThrows("Object.defineProperty(f, 'arguments', { value: {} })");
88