test/built-ins/Proxy/preventExtensions/return-true-target-is-extensible.js


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// Copyright (C) 2015 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
es6id: 9.5.4
description: >
    Throws a TypeError exception if boolean trap result is true and target is
    extensible.
info: |
    [[PreventExtensions]] ( )

    ...
    10. If booleanTrapResult is true, then
        ...
        c. If targetIsExtensible is true, throw a TypeError exception.
    11. Return booleanTrapResult.
    ...
---*/

var p = new Proxy({}, {
    preventExtensions: function(t) {
        return true;
    }
});

assert.throws(TypeError, function() {
    Object.preventExtensions(p);
});