Add m-esr52 at 52.6.0

1 files changed, 40 insertions, 0 deletions

diff --git a/js/src/tests/ecma_7/Destructuring/rest-parameter-aray-iterator.js b/js/src/tests/ecma_7/Destructuring/rest-parameter-aray-iterator.js
new file mode 100644
index 000000000..bf9643fd7
--- /dev/null
+++ b/js/src/tests/ecma_7/Destructuring/rest-parameter-aray-iterator.js
@@ -0,0 +1,40 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Destructuring rest arrays call the array iterator. This behaviour is
+// observable when Array.prototype[Symbol.iterator] is overridden.
+
+const oldArrayIterator = Array.prototype[Symbol.iterator];
+try {
+    let callCount = 0;
+    Array.prototype[Symbol.iterator] = function() {
+        callCount += 1;
+        return oldArrayIterator.call(this);
+    };
+
+    // Array iterator called exactly once.
+    function arrayIterCalledOnce(...[]) { }
+    assertEq(callCount, 0);
+    arrayIterCalledOnce();
+    assertEq(callCount, 1);
+
+    // Array iterator not called before rest parameter.
+    callCount = 0;
+    function arrayIterNotCalledBeforeRest(t = assertEq(callCount, 0), ...[]) { }
+    assertEq(callCount, 0);
+    arrayIterNotCalledBeforeRest();
+    assertEq(callCount, 1);
+
+    // Array iterator called when rest parameter is processed.
+    callCount = 0;
+    function arrayIterCalledWhenDestructuring(...[t = assertEq(callCount, 1)]) { }
+    assertEq(callCount, 0);
+    arrayIterCalledWhenDestructuring();
+    assertEq(callCount, 1);
+} finally {
+    Array.prototype[Symbol.iterator] = oldArrayIterator;
+}
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);