JSTests/test262/test/built-ins/TypedArray/prototype/slice/speciesctor-get-species-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%.prototype.slice
description: >
  Use custom @@species constructor if available
info: |
  22.2.3.24 %TypedArray%.prototype.slice ( start, end )

  ...
  9. Let A be ? TypedArraySpeciesCreate(O, « count »).
  ...

  22.2.4.7 TypedArraySpeciesCreate ( exemplar, argumentList )

  ...
  3. Let constructor be ? SpeciesConstructor(exemplar, defaultConstructor).
  4. Return ? TypedArrayCreate(constructor, argumentList).

  7.3.20 SpeciesConstructor ( O, defaultConstructor )

  ...
  5. Let S be ? Get(C, @@species).
  ...
  7. If IsConstructor(S) is true, return S.
  ...

  22.2.4.6 TypedArrayCreate ( constructor, argumentList )

  1. Let newTypedArray be ? Construct(constructor, argumentList).
  2. Perform ? ValidateTypedArray(newTypedArray).
  3. If argumentList is a List of a single Number, then
    ...
  4. Return newTypedArray.
includes: [testTypedArray.js, compareArray.js]
features: [Symbol.species, TypedArray]
---*/

testWithTypedArrayConstructors(function(TA) {
  var sample = new TA([40, 41, 42]);
  var calls = 0;
  var result;

  sample.constructor = {};
  sample.constructor[Symbol.species] = function(count) {
    calls++;
    return new TA(count);
  };

  result = sample.slice(1);

  assert.sameValue(calls, 1, "ctor called once");
  assert(compareArray(result, [41, 42]), "expected object");
});