tests/stress/array-from-with-iterator.js

   1 function shouldBe(actual, expected) {
   2     if (actual !== expected)
   3         throw new Error('bad value: ' + actual);
   4 }
   5
   6 function shouldThrow(func, message) {
   7     var error = null;
   8     try {
   9         func();
  10     } catch (e) {
  11         error = e;
  12     }
  13     if (!error)
  14         throw new Error("not thrown.");
  15     if (String(error) !== message)
  16         throw new Error("bad error: " + String(error));
  17 }
  18
  19 var originalArray = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
  20
  21 var array = Array.from(originalArray.values());
  22 shouldBe(array.length, originalArray.length);
  23 for (var i = 0; i < array.length; ++i) {
  24     shouldBe(array[i], originalArray[i]);
  25 }
  26
  27 function createIterator(callback) {
  28     var array = [0,1,2,3,4,5];
  29     var iterator = array[Symbol.iterator]();
  30     iterator.return = function () {
  31         iterator.returned = true;
  32         if (callback)
  33             return callback(this);
  34         return { done: true, value: undefined };
  35     };
  36     iterator.returned = false;
  37     return iterator;
  38 }
  39
  40 var iterator = createIterator();
  41 var result = Array.from(iterator);
  42 shouldBe(result.length, 6);
  43 for (var i = 0; i < 6; ++i) {
  44     shouldBe(result[i], i);
  45 }
  46 shouldBe(iterator.returned, false);
  47
  48 // mapFn raises an error.
  49 var iterator = createIterator();
  50 shouldThrow(function () {
  51     var result = Array.from(iterator, function () {
  52         throw new Error('map func');
  53     });
  54 }, "Error: map func");
  55 shouldBe(iterator.returned, true);
  56
  57 // mapFn raises an error and iterator.return also raises an error.
  58 var iterator = createIterator(function () {
  59     throw new Error('iterator.return');
  60 });
  61
  62 // An error raised in iterator.return is discarded.
  63 shouldThrow(function () {
  64     var result = Array.from(iterator, function () {
  65         throw new Error('map func');
  66     });
  67 }, "Error: map func");
  68 shouldBe(iterator.returned, true);
  69
  70 // iterable[Symbol.iterator] is not a function.
  71 shouldThrow(function () {
  72     var iterator = [].values();
  73     iterator[Symbol.iterator] = {};
  74     Array.from(iterator);
  75 }, "TypeError: Array.from requires that the property of the first argument, items[Symbol.iterator], when exists, be a function");
  76
  77 // iterable[Symbol.iterator] raises an error.
  78 shouldThrow(function () {
  79     var iterable = [];
  80     iterable[Symbol.iterator] = function () {
  81         throw new Error("iterator");
  82     };
  83     Array.from(iterable);
  84 }, "Error: iterator");
  85
  86 // iterable[Symbol.iterator] lookup is only once.
  87 (function () {
  88     var iterable = [0, 1, 2, 3, 4, 5];
  89     var count = 0;
  90     var iteratorCallCount = 0;
  91     Object.defineProperty(iterable, Symbol.iterator, {
  92         get() {
  93             ++count;
  94             return function () {
  95                 ++iteratorCallCount;
  96                 return this.values();
  97             };
  98         }
  99     });
 100     var generated = Array.from(iterable);
 101     shouldBe(generated.length, iterable.length);
 102     for (var i = 0; i < iterable.length; ++i) {
 103         shouldBe(generated[i], iterable[i]);
 104     }
 105     shouldBe(count, 1);
 106     shouldBe(iteratorCallCount, 1);
 107 }());
 108
 109 // The Symbol.iterator method of the iterator generated by iterable[Symbol.iterator] is not looked up.
 110 (function () {
 111     var iterable = [0, 1, 2, 3, 4, 5];
 112     var count = 0;
 113     iterable[Symbol.iterator] = function () {
 114         ++count;
 115         var iterator = this.values();
 116         Object.defineProperty(iterator, Symbol.iterator, {
 117             get() {
 118                 throw new Error('iterator[@@iterator] is touched');
 119             }
 120         });
 121         return iterator;
 122     };
 123     var generated = Array.from(iterable);
 124     shouldBe(generated.length, iterable.length);
 125     for (var i = 0; i < iterable.length; ++i) {
 126         shouldBe(generated[i], iterable[i]);
 127     }
 128     shouldBe(count, 1);
 129 }());