1 files changed, 49 insertions, 0 deletions
diff --git a/js/src/tests/non262/TypedArray/from_iterable.js b/js/src/tests/non262/TypedArray/from_iterable.js
new file mode 100644
index 0000000000..889c815898
--- /dev/null
+++ b/js/src/tests/non262/TypedArray/from_iterable.js
@@ -0,0 +1,49 @@
+for (var constructor of anyTypedArrayConstructors) {
+    // %TypedArray%.from works on arguments objects.
+    (function () {
+        assertDeepEq(constructor.from(arguments), new constructor(["0", "1", undefined]));
+    })("0", "1", undefined);
+
+    // If an object has both .length and [@@iterator] properties, [@@iterator] is used.
+    var a = ['0', '1', '2', '3', '4'];
+    a[Symbol.iterator] = function* () {
+        for (var i = 5; i--; )
+            yield this[i];
+    };
+
+    var log = '';
+    function f(x) {
+        log += x;
+        return x + x;
+    }
+
+    var b = constructor.from(a, f);
+    assertDeepEq(b, new constructor(['44', '33', '22', '11', '00']));
+    assertEq(log, '43210');
+
+    // In fact, if [@@iterator] is present, .length isn't queried at all.
+    var pa = new Proxy(a, {
+        has: function (target, id) {
+            if (id === "length")
+                throw new Error(".length should not be queried (has)");
+            return id in target;
+        },
+        get: function (target, id) {
+            if (id === "length")
+                throw new Error(".length should not be queried (get)");
+            return target[id];
+        },
+        getOwnPropertyDescriptor: function (target, id) {
+            if (id === "length")
+                throw new Error(".length should not be queried (getOwnPropertyDescriptor)");
+            return Object.getOwnPropertyDescriptor(target, id)
+        }
+    });
+    log = "";
+    b = constructor.from(pa, f);
+    assertDeepEq(b, new constructor(['44', '33', '22', '11', '00']));
+    assertEq(log, '43210');
+}
+
+if (typeof reportCompare === "function")
+    reportCompare(true, true);