buttons: Add keypress events to trigger user info popup.

This commit wraps up the feature PR by defining keypress
events to toggle user info view.

Tests added.
Fixes #511.

Author: Ezio-Sarthak

tests/ui_tools/test_buttons.py

@@ -253,6 +253,17 @@ def test_activate_called_once_on_keypress(
 
         assert activate.call_count == 1
 
+    @pytest.mark.parametrize('key', keys_for_command('USER_INFO'))
+    def test_keypress_USER_INFO(self, mocker, user_button, key,
+                                widget_size):
+        size = widget_size(user_button)
+        pop_up = mocker.patch(
+            'zulipterminal.core.Controller.show_user_info')
+
+        user_button.keypress(size, key)
+
+        pop_up.assert_called_once_with(user_button.user_id)
+
 
 class TestTopicButton:
     @pytest.mark.parametrize('width, count, stream_id, title, stream_name', [

zulipterminal/ui_tools/buttons.py

@@ -239,6 +239,7 @@ def __init__(self, user: Dict[str, Any], controller: Any,
         self.email = user['email']
         self.user_id = user['user_id']
 
+        self.controller = controller
         self._view = view  # Used in _narrow_with_compose
 
         # FIXME Is this still needed?
@@ -268,6 +269,11 @@ def _narrow_with_compose(self) -> None:
             recipient_user_ids=[self.user_id]
         )
 
+    def keypress(self, size: urwid_Size, key: str) -> Optional[str]:
+        if is_command_key('USER_INFO', key):
+            self.controller.show_user_info(self.user_id)
+        return super().keypress(size, key)
+
 
 class TopicButton(TopButton):
     def __init__(self, stream_id: int, topic: str,