views: Support 'j/k', 'J/K' and 'G/end' for navigation in the help menu.

This makes navigation more consistent throughout the user interface.

Tests added for extra keypress options in HelpView.

Fixes #517.

Author: preetmishra

tests/ui/test_ui_tools.py

@@ -1101,6 +1101,23 @@ def test_keypress_goback(self, key):
         self.help_view.keypress(size, key)
         assert self.controller.exit_popup.called
 
+    @pytest.mark.parametrize('key, expected_key', [
+        (key, expected_key)
+        for keys, expected_key in [
+            (keys_for_command('GO_UP'), 'up'),
+            (keys_for_command('GO_DOWN'), 'down'),
+            (keys_for_command('SCROLL_UP'), 'page up'),
+            (keys_for_command('SCROLL_DOWN'), 'page down'),
+            (keys_for_command('GO_TO_BOTTOM'), 'end'),
+        ]
+        for key in keys
+    ])
+    def test_keypress_navigation(self, mocker, key, expected_key):
+        size = (200, 20)
+        super_view = mocker.patch(VIEWS + '.urwid.ListBox.keypress')
+        self.help_view.keypress(size, key)
+        super_view.assert_called_once_with(size, expected_key)
+
 
 class TestPopUpConfirmationView:
     @pytest.fixture

zulipterminal/ui_tools/views.py

@@ -792,6 +792,16 @@ def __init__(self, controller: Any) -> None:
     def keypress(self, size: urwid_Size, key: str) -> str:
         if is_command_key('GO_BACK', key) or is_command_key('HELP', key):
             self.controller.exit_popup()
+        elif is_command_key('GO_UP', key):
+            key = 'up'
+        elif is_command_key('GO_DOWN', key):
+            key = 'down'
+        elif is_command_key('SCROLL_UP', key):
+            key = 'page up'
+        elif is_command_key('SCROLL_DOWN', key):
+            key = 'page down'
+        elif is_command_key('GO_TO_BOTTOM', key):
+            key = 'end'
         return super().keypress(size, key)