1 files changed, 55 insertions, 0 deletions
diff --git a/js/src/tests/non262/Array/from_proxy.js b/js/src/tests/non262/Array/from_proxy.js
new file mode 100644
index 0000000000..c3c82d0b7e
--- /dev/null
+++ b/js/src/tests/non262/Array/from_proxy.js
@@ -0,0 +1,55 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/ */
+
+// Two tests involving Array.from and a Proxy.
+var log = [];
+function LoggingProxy(target) {
+    var h = {
+        defineProperty: function (t, id) {
+            log.push("define", id);
+            return true;
+        },
+        has: function (t, id) {
+            log.push("has", id);
+            return id in t;
+        },
+        get: function (t, id) {
+            log.push("get", id);
+            return t[id];
+        },
+        set: function (t, id, v) {
+            log.push("set", id);
+            t[id] = v;
+            return true;
+        }
+    };
+    return new Proxy(target || [], h);
+}
+
+// When the new object created by Array.from is a Proxy,
+// Array.from calls handler.defineProperty to create new elements
+// but handler.set to set the length.
+LoggingProxy.from = Array.from;
+LoggingProxy.from([3, 4, 5]);
+assertDeepEq(log, ["define", "0", "define", "1", "define", "2", "set", "length"]);
+
+// When the argument passed to Array.from is a Proxy, Array.from
+// calls handler.get on it.
+log = [];
+assertDeepEq(Array.from(new LoggingProxy([3, 4, 5])), [3, 4, 5]);
+assertDeepEq(log, ["get", Symbol.iterator,
+                   "get", "length", "get", "0",
+                   "get", "length", "get", "1",
+                   "get", "length", "get", "2",
+                   "get", "length"]);
+
+// Array-like iteration only gets the length once.
+log = [];
+var arr = [5, 6, 7];
+arr[Symbol.iterator] = undefined;
+assertDeepEq(Array.from(new LoggingProxy(arr)), [5, 6, 7]);
+assertDeepEq(log, ["get", Symbol.iterator,
+                   "get", "length", "get", "0", "get", "1", "get", "2"]);
+
+if (typeof reportCompare === 'function')
+    reportCompare(0, 0);