On macOS, native context menus do not respond to synthesized events, such as mousemove, click, or key presses. However, we have many automated tests which use synthesized events to interact with context menus.

This bug tracks converting our existing tests to menu.openMenu(true) for opening submenus, and popup.activateItem(menuitem) (new from bug 1704206) for clicking items.

Example:

diff --git a/browser/components/extensions/test/browser/head.js b/browser/components/extensions/test/browser/head.js
--- a/browser/components/extensions/test/browser/head.js
+++ b/browser/components/extensions/test/browser/head.js
@@ -490,31 +490,31 @@ async function openExtensionContextMenu(
     return null;
   }
 
   let extensionMenu = topLevelMenu[0];
   let popupShownPromise = BrowserTestUtils.waitForEvent(
     contextMenu,
     "popupshown"
   );
-  EventUtils.synthesizeMouseAtCenter(extensionMenu, {});
+  extensionMenu.openMenu(true);
   await popupShownPromise;
   return extensionMenu;
 }
 
 async function closeExtensionContextMenu(itemToSelect, modifiers = {}) {
   let contentAreaContextMenu = document.getElementById(
     "contentAreaContextMenu"
   );
   let popupHiddenPromise = BrowserTestUtils.waitForEvent(
     contentAreaContextMenu,
     "popuphidden"
   );
   if (itemToSelect) {
-    EventUtils.synthesizeMouseAtCenter(itemToSelect, modifiers);
+    contentAreaContextMenu.activateItem(itemToSelect, modifiers);
   } else {
     contentAreaContextMenu.hidePopup();
   }
   await popupHiddenPromise;
 
   // Bug 1351638: parent menu fails to close intermittently, make sure it does.
   contentAreaContextMenu.hidePopup();
 }

This is done. At least half of the patches under bugs blocking bug 1700724 fell under this category.