JSTests/test262/test/language/expressions/delete/11.4.1-4.a-6.js

// Copyright (c) 2012 Ecma International.  All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/*---
info: |
    This test is actually testing the [[Delete]] internal method (8.12.8). Since the
    language provides no way to directly exercise [[Delete]], the tests are placed here.
es5id: 11.4.1-4.a-6
description: delete operator returns true when deleting a property inside 'with'
flags: [noStrict]
---*/

  var o = new Object();
  o.x = 1;
  var d;
  with(o)
  {
    d = delete x;
  }

assert.sameValue(d, true, 'd');
assert.sameValue(o.x, undefined, 'o.x');