1 files changed, 35 insertions, 0 deletions
diff --git a/browser/components/customizableui/test/browser_877447_skip_missing_ids.js b/browser/components/customizableui/test/browser_877447_skip_missing_ids.js
new file mode 100644
index 0000000000..83e7edbba3
--- /dev/null
+++ b/browser/components/customizableui/test/browser_877447_skip_missing_ids.js
@@ -0,0 +1,35 @@
+/* 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";
+
+registerCleanupFunction(removeCustomToolbars);
+
+add_task(function skipMissingIDS() {
+  const kButtonId = "look-at-me-disappear-button";
+  CustomizableUI.reset();
+  ok(CustomizableUI.inDefaultState, "Should be in the default state.");
+  let btn = createDummyXULButton(kButtonId, "Gone!");
+  CustomizableUI.addWidgetToArea(kButtonId, CustomizableUI.AREA_NAVBAR);
+  ok(
+    !CustomizableUI.inDefaultState,
+    "Should no longer be in the default state."
+  );
+  is(
+    btn.parentNode.parentNode.id,
+    CustomizableUI.AREA_NAVBAR,
+    "Button should be in navbar"
+  );
+  btn.remove();
+  is(btn.parentNode, null, "Button is no longer in the navbar");
+  ok(
+    CustomizableUI.inDefaultState,
+    "Should be back in the default state, " +
+      "despite unknown button ID in placements."
+  );
+});
+
+add_task(async function asyncCleanup() {
+  await resetCustomization();
+});