1 files changed, 50 insertions, 0 deletions
diff --git a/js/src/tests/ecma_6/Array/from_iterable.js b/js/src/tests/ecma_6/Array/from_iterable.js
new file mode 100644
index 000000000..568181961
--- /dev/null
+++ b/js/src/tests/ecma_6/Array/from_iterable.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/ */
+
+// Array.from works on arguments objects.
+(function () {
+    assertDeepEq(Array.from(arguments), ["arg0", "arg1", undefined]);
+})("arg0", "arg1", undefined);
+
+// If an object has both .length and [@@iterator] properties, [@@iterator] is used.
+var a = ['a', 'e', 'i', 'o', 'u'];
+a[Symbol.iterator] = function* () {
+    for (var i = 5; i--; )
+        yield this[i];
+};
+
+var log = '';
+function f(x) {
+    log += x;
+    return x + x;
+}
+
+var b = Array.from(a, f);
+assertDeepEq(b, ['uu', 'oo', 'ii', 'ee', 'aa']);
+assertEq(log, 'uoiea');
+
+// 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 = Array.from(pa, f);
+assertDeepEq(b, ['uu', 'oo', 'ii', 'ee', 'aa']);
+assertEq(log, 'uoiea');
+
+if (typeof reportCompare === 'function')
+    reportCompare(0, 0);