bugfix: views: Handle empty search in PanelSearchBox's update functions.

This left strips search text to restrict empty search and avoid empty
search results.

Tests amended.

Author: preetmishra

tests/ui/test_ui_tools.py

@@ -445,7 +445,7 @@ def test_update_streams(self, mocker, stream_view, new_text, expected_log,
 
     @pytest.mark.parametrize('new_text', [
         '',
-        pytest.param(' ', marks=pytest.mark.xfail(reason='bug')),
+        ' ',
     ])
     def test_update_streams_empty_string(self, mocker, stream_view, new_text):
         # NOTE: Only do a minimal arrangement to test whether the method
@@ -580,7 +580,7 @@ def test_update_topics(self, mocker, topic_view, new_text, expected_log):
 
     @pytest.mark.parametrize('new_text', [
         '',
-        pytest.param(' ', marks=pytest.mark.xfail(reason='bug')),
+        ' ',
     ])
     def test_update_topics_empty_string(self, mocker, topic_view, new_text):
         # NOTE: Only do a minimal arrangement to test whether the method
@@ -1007,9 +1007,10 @@ def test_update_user_list_editor_mode(self, mocker, right_col_view):
     @pytest.mark.parametrize(['search_string', 'assert_list',
                               'match_return_value'], [
         ('U', ["USER1", "USER2"], True),
-        ('F', [], False)
+        ('F', [], False),
+        (' ', ["USER1", "USER2"], True),
     ], ids=[
-        'user match', 'no user match',
+        'user match', 'no user match', 'empty search',
     ])
     def test_update_user_list(self, right_col_view, mocker,
                               search_string, assert_list, match_return_value):
@@ -1030,7 +1031,6 @@ def test_update_user_presence(self, right_col_view, mocker,
         set_body = mocker.patch(VIEWS + ".urwid.Frame.set_body")
 
         right_col_view.update_user_list(user_list=user_list)
-
         right_col_view.users_view.assert_called_with(user_list)
         set_body.assert_called_once_with(right_col_view.body)
 

zulipterminal/ui_tools/views.py

@@ -264,6 +264,7 @@ def __init__(self, streams_btn_list: List[Any], view: Any) -> None:
 
     @asynch
     def update_streams(self, search_box: Any, new_text: str) -> None:
+        new_text = new_text.lstrip()
         if not self.view.controller.is_in_editor_mode() or not new_text:
             return
         # wait for any previously started search to finish to avoid
@@ -331,6 +332,7 @@ def __init__(self, topics_btn_list: List[Any], view: Any,
 
     @asynch
     def update_topics(self, search_box: Any, new_text: str) -> None:
+        new_text = new_text.lstrip()
         if not self.view.controller.is_in_editor_mode() or not new_text:
             return
         # wait for any previously started search to finish to avoid
@@ -568,6 +570,7 @@ def update_user_list(self, search_box: Any=None,
                 or (user_list is not None and search_box is None
                     and new_text == ""))
 
+        new_text = new_text.lstrip()
         if not self.view.controller.is_in_editor_mode() and not user_list:
             return
         if not self.allow_update_user_list and new_text == "":