1 files changed, 60 insertions, 0 deletions
diff --git a/browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js b/browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js
new file mode 100644
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+++ b/browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js
@@ -0,0 +1,60 @@
+/* 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/. */
+
+"use strict";
+
+const kHidden1Id = "test-hidden-button-1";
+const kHidden2Id = "test-hidden-button-2";
+
+var navbar = document.getElementById(CustomizableUI.AREA_NAVBAR);
+
+// When we drag an item onto a customizable area, and not over a specific target, we
+// should assume that we're appending them to the area. If doing so, we should scan
+// backwards over any hidden items and insert the item before those hidden items.
+add_task(async function () {
+  ok(CustomizableUI.inDefaultState, "Should be in the default state");
+
+  // Iterate backwards over the items in the nav-bar until we find the first
+  // one that is not hidden.
+  let placements = CustomizableUI.getWidgetsInArea(CustomizableUI.AREA_NAVBAR);
+  let lastVisible = null;
+  for (let widgetGroup of placements.reverse()) {
+    let widget = widgetGroup.forWindow(window);
+    if (widget && widget.node && !widget.node.hidden) {
+      lastVisible = widget.node;
+      break;
+    }
+  }
+
+  if (!lastVisible) {
+    ok(false, "Apparently, there are no visible items in the nav-bar.");
+  }
+
+  info("The last visible item in the nav-bar has ID: " + lastVisible.id);
+
+  let hidden1 = createDummyXULButton(kHidden1Id, "You can't see me");
+  let hidden2 = createDummyXULButton(kHidden2Id, "You can't see me either.");
+  hidden1.hidden = hidden2.hidden = true;
+
+  // Make sure we have some hidden items at the end of the nav-bar.
+  CustomizableUI.addWidgetToArea(kHidden1Id, "nav-bar");
+  CustomizableUI.addWidgetToArea(kHidden2Id, "nav-bar");
+
+  // Drag an item and drop it onto the nav-bar customization target, but
+  // not over a particular item.
+  await startCustomizing();
+  let homeButton = document.getElementById("home-button");
+  let navbarTarget = CustomizableUI.getCustomizationTarget(navbar);
+  simulateItemDrag(homeButton, navbarTarget, "end");
+
+  await endCustomizing();
+
+  is(
+    homeButton.previousElementSibling.id,
+    lastVisible.id,
+    "The downloads button should be placed after the last visible item."
+  );
+
+  await resetCustomization();
+});