ui: Periodically cycle random footer hint.

Switch to using urwid's alarm instead of time.sleep(),
as that timer can be cancelled when a new footer event arrives.

Update test using freezegun.

Author: Niloth-p

tests/ui/test_ui.py

@@ -1,6 +1,7 @@
 from typing import Any, Callable, List, Optional
 
 import pytest
+from freezegun import freeze_time  # type: ignore [import-untyped]
 from pytest_mock import MockerFixture
 from urwid import Widget
 
@@ -109,14 +110,21 @@ def test_set_footer_text_with_duration(
         duration: Optional[float] = 5.3,
     ) -> None:
         mocker.patch(VIEW + ".get_random_help", return_value=["some help text"])
-        mock_sleep = mocker.patch("time.sleep")
+        mocked_alarm = mocker.patch(CONTROLLER + ".loop.set_alarm_in")
 
-        view.set_footer_text([custom_text], duration=duration)
+        with freeze_time() as frozen_datetime:
+            view.set_footer_text([custom_text], duration=duration)
 
-        view.frame.footer.set_text.assert_has_calls(
-            [mocker.call([custom_text]), mocker.call(["some help text"])]
-        )
-        mock_sleep.assert_called_once_with(duration)
+            view.frame.footer.set_text.assert_called_once_with([custom_text])
+            assert view.controller.update_screen.call_count == 1
+
+            frozen_datetime.tick(duration)
+
+            # Trigger the alarm
+            alarm_callback = mocked_alarm.call_args[0][1]
+            alarm_callback(None, None)
+
+        view.frame.footer.set_text.assert_called_with(["some help text"])
         assert view.controller.update_screen.call_count == 2
 
     @pytest.mark.parametrize(

zulipterminal/ui.py

@@ -4,7 +4,6 @@
 
 import random
 import re
-import time
 from typing import Any, Dict, List, Optional
 
 import urwid
@@ -120,7 +119,7 @@ def set_footer_text(
         self,
         text_list: Optional[List[Any]] = None,
         style: str = "footer",
-        duration: Optional[float] = None,
+        duration: Optional[float] = 30,
     ) -> None:
         # Avoid updating repeatedly (then pausing and showing default text)
         # This is simple, though doesn't avoid starting one thread for each call
@@ -134,10 +133,14 @@ def set_footer_text(
         self.frame.footer.set_text(text)
         self.frame.footer.set_attr_map({None: style})
         self.controller.update_screen()
+
+        if hasattr(self, "_footer_alarm_handle"):
+            self.controller.loop.remove_alarm(self._footer_alarm_handle)
         if duration is not None:
             assert duration > 0
-            time.sleep(duration)
-            self.set_footer_text()
+            self._footer_alarm_handle: Any = self.controller.loop.set_alarm_in(
+                duration, lambda loop, user_data: self.set_footer_text()
+            )
 
     @asynch
     def set_typeahead_footer(