test/mjsunit/es6/typedarray-tostring.js

// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Array's toString should call the object's own join method, if one exists and
// is callable. Otherwise, just use the original Object.toString function.

var typedArrayConstructors = [
  Uint8Array,
  Int8Array,
  Uint16Array,
  Int16Array,
  Uint32Array,
  Int32Array,
  Uint8ClampedArray,
  Float32Array,
  Float64Array
];

for (var constructor of typedArrayConstructors) {
  var success = "[test success]";
  var expectedThis;
  function testJoin() {
    assertEquals(0, arguments.length);
    assertSame(expectedThis, this);
    return success;
  }


  // On an Array object.

  // Default case.
  var a1 = new constructor([1, 2, 3]);
  assertEquals("1,2,3", a1.toString());
  assertEquals("1,2,3", a1.join());
  assertEquals("1,2,3", a1.toLocaleString());

  // Non-standard "join" function is called correctly.
  var a2 = new constructor([1, 2, 3]);
  a2.join = testJoin;
  expectedThis = a2;
  assertEquals(success, a2.toString());
  assertEquals(success, a2.join());
  assertEquals("1,2,3", a2.toLocaleString());

  // Non-callable join function is ignored and Object.prototype.toString is
  // used instead.
  var a3 = new constructor([1, 2, 3]);
  a3.join = "not callable";
  assertEquals(0, a3.toString().search(/\[object .+Array\]/));

  // Non-existing join function is treated same as non-callable.
  var a4 = new constructor([1, 2, 3]);
  a4.__proto__ = { toString: constructor.prototype.toString };
  // No join on Array.
  assertEquals(0, a3.toString().search(/\[object .+Array\]/));


  // On a non-Array object, throws.
  var o1 = {length: 3, 0: 1, 1: 2, 2: 3,
            toString: constructor.prototype.toString,
            join: constructor.prototype.join,
            toLocaleString: constructor.prototype.toLocaleString};
  assertThrows(function() { o1.join() }, TypeError);
  assertThrows(function() { o1.toString() }, TypeError);
  assertThrows(function() { o1.toLocaleString() }, TypeError);
  // toString is OK if join not from here:
  o1.join = Array.prototype.join;
  assertEquals("1,2,3", o1.join());
  assertEquals("1,2,3", o1.toString());
  assertThrows(function() { o1.toLocaleString() }, TypeError);
  // TODO(littledan): Use the same function for TypedArray as for
  // Array, as the spec says (but Firefox doesn't do either).
  // Currently, using the same method leads to a bootstrap failure.
  // assertEquals(o1.toString, Array.prototype.toString);

  // Redefining length does not change result
  var a5 = new constructor([1, 2, 3])
  Object.defineProperty(a5, 'length', { value: 2 });
  assertEquals("1,2,3", a5.join());
  assertEquals("1,2,3", a5.toString());
  assertEquals("1,2,3", a5.toLocaleString());
  assertEquals("1,2", Array.prototype.join.call(a5));
  assertEquals("1,2,3", Array.prototype.toString.call(a5));
  assertEquals("1,2", Array.prototype.toLocaleString.call(a5));
}