1 files changed, 13 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/for-of/array-holes-slow.js b/js/src/jit-test/tests/for-of/array-holes-slow.js
new file mode 100644
index 0000000000..7478ee6ac4
--- /dev/null
+++ b/js/src/jit-test/tests/for-of/array-holes-slow.js
@@ -0,0 +1,13 @@
+// for-of on a slow Array consults the prototype chain when it encounters a hole.
+
+var a = [0, , , 3];
+a.slow = true;
+Object.prototype[1] = 'peek1';
+Array.prototype[2] = 'peek2';
+
+var log = [];
+for (var x of a)
+    log.push(x);
+assertEq(log[1], 'peek1');
+assertEq(log[2], 'peek2');
+assertEq(log.join(), "0,peek1,peek2,3");