JSTests/test262/test/built-ins/TypedArrayConstructors/from/new-instance-using-custom-ctor.js

// Copyright (C) 2016 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-%typedarray%.from
description: >
  Return a new TypedArray using a custom Constructor
includes: [testTypedArray.js]
features: [TypedArray]
---*/

var source = [42, 43, 42];

testWithTypedArrayConstructors(function(TA) {
  var called = 0;

  var ctor = function(len) {
    assert.sameValue(arguments.length, 1);
    called++;
    return new TA(len);
  };

  var result = TA.from.call(ctor, source);
  assert.sameValue(result.length, 3);
  assert.sameValue(result[0], 42);
  assert.sameValue(result[1], 43);
  assert.sameValue(result[2], 42);
  assert.sameValue(result.constructor, TA);
  assert.sameValue(Object.getPrototypeOf(result), TA.prototype);
  assert.sameValue(called, 1);
});