Wait for macOS focus restoration to land

dikte/app.py

@@ -637,12 +637,24 @@ class Dikte:
         # inactive: at forty the title bar visibly blinks, at ten it does not.
         # Two messages to AppKit per tick, for at most a second and a half.
         watch.setInterval(10)
+        # activateWithOptions: answers whether macOS accepted the request, not
+        # whether the other application is already back in front.  Keep the
+        # watch alive until that asynchronous handoff is observable; on Intel
+        # Macs it can take hundreds of milliseconds after the call returned.
+        restore_requested = False
 
         def look():
-            if mac_window.is_frontmost():
-                mac_window.activate(was_in_front)
+            nonlocal restore_requested
+            if time.monotonic() > deadline:
                 self._stop_watching_the_front()
-            elif time.monotonic() > deadline:
+                return
+            if mac_window.is_frontmost():
+                if not restore_requested:
+                    restore_requested = mac_window.activate(was_in_front)
+            elif restore_requested:
+                # The request has landed.  Stop only now, rather than as soon
+                # as AppKit accepted it, so a delayed or failed handoff stays
+                # under observation until the deadline guard above.
                 self._stop_watching_the_front()
 
         watch.timeout.connect(look)

tests/test_ui.py

@@ -604,7 +604,7 @@ class GivingTheFrontBack(DikteTest):
         from dikte import mac_window
         self.dikte = dikte_module
         self.activated = []
-        self.patch_attr(mac_window, "activate", self.activated.append)
+        self.patch_attr(mac_window, "activate", self.activate)
         self.ticks = []
         outer = self
 
@@ -645,6 +645,10 @@ class GivingTheFrontBack(DikteTest):
 
         self.bare = BareDikte
 
+    def activate(self, pid):
+        self.activated.append(pid)
+        return True
+
     def watching(self, was_in_front, dikte_in_front, on=None):
         from dikte import mac_window
         self.patch_attr(mac_window, "is_frontmost", lambda: dikte_in_front)
@@ -656,7 +660,36 @@ class GivingTheFrontBack(DikteTest):
         watch = self.watching(4242, dikte_in_front=True)
         watch.tick()
         self.assertEqual(self.activated, [4242])
-        self.assertFalse(watch.running)   # one is enough; it stops watching
+        self.assertTrue(watch.running)    # accepted is not the same as landed
+        self.patch_attr(self.mac_window_module(), "is_frontmost", lambda: False)
+        watch.tick()
+        self.assertFalse(watch.running)
+
+    def test_an_accepted_restore_is_not_sent_again_while_it_is_landing(self):
+        watch = self.watching(4242, dikte_in_front=True)
+        watch.tick()
+        watch.tick()
+        self.assertEqual(self.activated, [4242])
+        self.assertTrue(watch.running)
+
+    def test_an_accepted_restore_that_never_lands_still_times_out(self):
+        watch = self.watching(4242, dikte_in_front=True)
+        watch.tick()
+        with mock.patch.object(self.dikte.time, "monotonic",
+                               return_value=self.dikte.time.monotonic() + 60):
+            watch.tick()
+        self.assertFalse(watch.running)
+        self.assertEqual(self.activated, [4242])
+
+    def test_a_restore_the_system_refused_is_retried(self):
+        from dikte import mac_window
+        self.patch_attr(mac_window, "activate",
+                        lambda pid: self.activated.append(pid) or False)
+        watch = self.watching(4242, dikte_in_front=True)
+        watch.tick()
+        watch.tick()
+        self.assertEqual(self.activated, [4242, 4242])
+        self.assertTrue(watch.running)
 
     def test_a_front_that_was_never_taken_is_left_where_it_is(self):
         """The microphone does not always take it, and pulling an application