Implement Array.from()

test/mjsunit/harmony/array-from.js

+// Copyright 2014 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.
+
+// Flags: --harmony-arrays --harmony-generators --harmony-collections --harmony-iteration
+(function() {
+
+assertEquals(1, Array.from.length);
+
+function testArrayFrom(thisArg, constructor) {
+  assertArrayLikeEquals(Array.from.call(thisArg, NaN), [], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, Infinity), [], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, 10000000), [], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, 'test'), ['t', 'e', 's', 't'], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, {length: 1, '0': { 'foo': 'bar' }}), [{'foo': 'bar'}], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, {length: -1, '0': { 'foo': 'bar' }}), [], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, ['foo', 'bar', 'baz']), ['foo', 'bar', 'baz'], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, (new Set).add('foo').add('bar').add('baz')), ['foo', 'bar', 'baz'], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, (new Map).set(0, 'foo').set(1, 'bar').set(2, 'baz')), [[0, 'foo'], [1, 'bar'], [2, 'baz']], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, generator()), ['a', 'b', 'c'], constructor);
+
+  // Mozilla:
+  // Array.from on a string handles surrogate pairs correctly.
+  var gclef = "\uD834\uDD1E"; // U+1D11E MUSICAL SYMBOL G CLEF
+  assertArrayLikeEquals(Array.from.call(thisArg, gclef), [gclef], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, gclef + " G"), [gclef, " ", "G"], constructor);
+
+  assertArrayLikeEquals(Array.from.call(thisArg, 'test', function(x) {
+    return this.filter(x);
+  }, {
+    filter: function(x) { return x.toUpperCase(); }
+  }), ['T', 'E', 'S', 'T'], constructor);
+  assertArrayLikeEquals(Array.from.call(thisArg, 'test', function(x) {
+    return x.toUpperCase();
+  }), ['T', 'E', 'S', 'T'], constructor);
+
+  this.thisArg = thisArg;
+  assertThrows('Array.from.call(thisArg, null)', TypeError);
+  assertThrows('Array.from.call(thisArg, undefined)', TypeError);
+
+  this.nullIterator = {};
+  nullIterator[Symbol.iterator] = null;
+  assertThrows('Array.from.call(thisArg, nullIterator)', TypeError);
+
+  this.nonObjIterator = {};
+  nonObjIterator[Symbol.iterator] = function() { return "nonObject"; };
+  assertThrows('Array.from.call(thisArg, nonObjIterator)', TypeError);
+
+  assertThrows('Array.from.call(thisArg, [], null)', TypeError);
+}
+
+testArrayFrom(Array, Array);
+testArrayFrom(null, Array);
+testArrayFrom({}, Array);
+testArrayFrom(Object, Object);
+testArrayFrom(Other, Other);
+
+function Other() {}
+
+function* generator() {
+  yield 'a';
+  yield 'b';
+  yield 'c';
+}
+
+function assertArrayLikeEquals(value, expected, type) {
+  assertInstanceof(value, type);
+  assertEquals(expected.length, value.length);
+  for (var i=0; i<value.length; ++i) {
+    assertEquals(expected[i], value[i]);
+  }
+}
+
+})();