1 files changed, 71 insertions, 0 deletions
diff --git a/js/xpconnect/tests/unit/test_wrapped_js_enumerator.js b/js/xpconnect/tests/unit/test_wrapped_js_enumerator.js
new file mode 100644
index 0000000000..5a366ba25d
--- /dev/null
+++ b/js/xpconnect/tests/unit/test_wrapped_js_enumerator.js
@@ -0,0 +1,71 @@
+"use strict";
+
+// Tests that JS iterators are automatically wrapped into
+// equivalent nsISimpleEnumerator objects.
+
+const Variant = Components.Constructor("@mozilla.org/variant;1",
+                                       "nsIWritableVariant",
+                                       "setFromVariant");
+const SupportsInterfacePointer = Components.Constructor(
+  "@mozilla.org/supports-interface-pointer;1", "nsISupportsInterfacePointer");
+
+function wrapEnumerator1(iter) {
+  var ip = SupportsInterfacePointer();
+  ip.data = iter;
+  return ip.data.QueryInterface(Ci.nsISimpleEnumerator);
+}
+
+function wrapEnumerator2(iter) {
+  var ip = SupportsInterfacePointer();
+  ip.data = {
+    QueryInterface: ChromeUtils.generateQI(["nsIFilePicker"]),
+    get files() {
+      return iter;
+    },
+  };
+  return ip.data.QueryInterface(Ci.nsIFilePicker).files;
+}
+
+
+function enumToArray(iter) {
+  let result = [];
+  while (iter.hasMoreElements()) {
+    result.push(iter.getNext().QueryInterface(Ci.nsIVariant));
+  }
+  return result;
+}
+
+add_task(async function test_wrapped_js_enumerator() {
+  let array = [1, 2, 3, 4];
+
+  for (let wrapEnumerator of [wrapEnumerator1, wrapEnumerator2]) {
+    // Test a plain JS iterator. This should automatically be wrapped into
+    // an equivalent nsISimpleEnumerator.
+    {
+      let iter = wrapEnumerator(array.values());
+      let result = enumToArray(iter);
+
+      deepEqual(result, array, "Got correct result");
+    }
+
+    // Test an object with a QueryInterface method, which implements
+    // nsISimpleEnumerator. This should be wrapped and used directly.
+    {
+      let obj = {
+        QueryInterface: ChromeUtils.generateQI(["nsISimpleEnumerator"]),
+        _idx: 0,
+        hasMoreElements() {
+          return this._idx < array.length;
+        },
+        getNext() {
+          return Variant(array[this._idx++]);
+        },
+      };
+
+      let iter = wrapEnumerator(obj);
+      let result = enumToArray(iter);
+
+      deepEqual(result, array, "Got correct result");
+    }
+  }
+});