buttons/views: Add keypress events to trigger full message popup view.

This commit adds event to trigger full message view on pressing
binded key 'f' in message info view.

Visual change:
 * Hotkey help for full msg view appended in message info popup.

Tests amended.
Tests added (for added keypress events).

Author: Ezio-Sarthak

tests/ui_tools/test_popups.py

@@ -586,6 +586,21 @@ def test_keypress_edit_history(self, message_fixture, key, widget_size,
         else:
             self.controller.show_edit_history.assert_not_called()
 
+    @pytest.mark.parametrize('key', keys_for_command('FULL_MSG_VIEW'))
+    def test_keypress_full_msg(self, message_fixture, key, widget_size):
+        msg_info_view = MsgInfoView(self.controller, message_fixture,
+                                    title='Message Information',
+                                    message_links=OrderedDict(),
+                                    time_mentions=list())
+        size = widget_size(msg_info_view)
+        msg_info_view.keypress(size, key)
+
+        self.controller.show_full_msg.assert_called_once_with(
+            message=message_fixture,
+            message_links=OrderedDict(),
+            time_mentions=list(),
+        )
+
     @pytest.mark.parametrize('key', {*keys_for_command('GO_BACK'),
                                      *keys_for_command('MSG_INFO')})
     def test_keypress_exit_popup(self, key, widget_size):
@@ -594,7 +609,7 @@ def test_keypress_exit_popup(self, key, widget_size):
         assert self.controller.exit_popup.called
 
     def test_height_noreactions(self):
-        expected_height = 3
+        expected_height = 4           # +1 due to full msg view key
         assert self.msg_info_view.height == expected_height
 
     # FIXME This is the same parametrize as MessageBox:test_reactions_view
@@ -642,8 +657,9 @@ def test_height_reactions(self, message_fixture, to_vary_in_each_message):
         self.msg_info_view = MsgInfoView(self.controller, varied_message,
                                          'Message Information', OrderedDict(),
                                          list())
-        # 9 = 3 labels + 1 blank line + 1 'Reactions' (category) + 4 reactions.
-        expected_height = 9
+        # 10 = 4 labels + 1 blank line + 1 'Reactions' (category)
+        # + 4 reactions.
+        expected_height = 10
         assert self.msg_info_view.height == expected_height
 
     def test_keypress_navigation(self, mocker, widget_size,

zulipterminal/ui_tools/views.py

@@ -1219,10 +1219,13 @@ def __init__(self, controller: Any, msg: Message, title: str,
             msg['timestamp'], show_seconds=True, show_year=True
         )
 
+        full_msg_keys = ', '.join(map(repr, keys_for_command('FULL_MSG_VIEW')))
         msg_info = [
             ('', [('Date & Time', date_and_time),
                   ('Sender', msg['sender_full_name']),
-                  ('Sender\'s Email ID', msg['sender_email'])]),
+                  ('Sender\'s Email ID', msg['sender_email']),
+                  ('Full message view', 'Press {} to view'
+                   .format(full_msg_keys))]),
         ]
         # Only show the 'Edit History' label for edited messages.
         self.show_edit_history_label = (
@@ -1293,6 +1296,13 @@ def keypress(self, size: urwid_Size, key: str) -> str:
                 message_links=self.message_links,
                 time_mentions=self.time_mentions,
             )
+        elif (is_command_key('FULL_MSG_VIEW', key)):
+            self.controller.show_full_msg(
+                message=self.msg,
+                message_links=self.message_links,
+                time_mentions=self.time_mentions,
+            )
+            return key
         return super().keypress(size, key)