1 files changed, 48 insertions, 0 deletions
diff --git a/browser/components/customizableui/test/browser_flexible_space_area.js b/browser/components/customizableui/test/browser_flexible_space_area.js
new file mode 100644
index 0000000000..f3189096de
--- /dev/null
+++ b/browser/components/customizableui/test/browser_flexible_space_area.js
@@ -0,0 +1,48 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function getSpringCount(area) {
+  return CustomizableUI.getWidgetIdsInArea(area).filter(id =>
+    id.includes("spring")
+  ).length;
+}
+
+/**
+ * Check that no matter where we add a flexible space, we
+ * never end up without a flexible space in the palette.
+ */
+add_task(async function test_flexible_space_addition() {
+  await startCustomizing();
+  let palette = document.getElementById("customization-palette");
+  // Make the bookmarks toolbar visible:
+  CustomizableUI.setToolbarVisibility(CustomizableUI.AREA_BOOKMARKS, true);
+  let areas = [CustomizableUI.AREA_NAVBAR, CustomizableUI.AREA_BOOKMARKS];
+  if (AppConstants.platform != "macosx") {
+    areas.push(CustomizableUI.AREA_MENUBAR);
+  }
+
+  for (let area of areas) {
+    let spacer = palette.querySelector("toolbarspring");
+    let toolbar = document.getElementById(area);
+    toolbar = CustomizableUI.getCustomizationTarget(toolbar);
+
+    let springCount = getSpringCount(area);
+    simulateItemDrag(spacer, toolbar);
+    // Check we added the spring:
+    is(
+      springCount + 1,
+      getSpringCount(area),
+      "Should now have an extra spring"
+    );
+
+    // Check there's still one in the palette:
+    let newSpacer = palette.querySelector("toolbarspring");
+    ok(newSpacer, "Should have created a new spring");
+  }
+});
+registerCleanupFunction(async function asyncCleanup() {
+  await endCustomizing();
+  await resetCustomization();
+});