Handle read events from server

Fixes #434

Author: kaustubh-nair

tests/model/test_model.py

@@ -1154,7 +1154,7 @@ def test_update_reaction_remove_reaction(self, mocker, model, response,
 
     def test_update_star_status_no_index(self, mocker, model):
         model.index = dict(messages={})  # Not indexed
-        event = dict(messages=[1], flag='starred', all=False)
+        event = dict(messages=[1], flag='starred', all=False, operation='add')
         mocker.patch('zulipterminal.model.Model.update_rendered_view')
 
         model.update_message_flag_status(event)
@@ -1221,6 +1221,51 @@ def test_update_star_status(self, mocker, model, event_op,
             assert (model.index['messages'][unchanged_id]['flags'] ==
                     flags_before)
 
+    @pytest.mark.parametrize('event_message_ids, indexed_ids', [
+        ([1], [1]),
+        ([1, 2], [1]),
+        ([1, 2], [1, 2]),
+        ([1], [1, 2]),
+        ([], [1, 2]),
+        ([1, 2], []),
+    ])
+    @pytest.mark.parametrize('event_op, flags_before, flags_after', [
+        ('add', [], ['read']),
+        ('add', ['read'], ['read']),
+        ('add', ['starred'], ['starred', 'read']),
+        ('add', ['read', 'starred'], ['read', 'starred']),
+    ])
+    def test_update_read_status(self, mocker, model, event_op,
+                                event_message_ids, indexed_ids,
+                                flags_before, flags_after):
+        model.index = dict(messages={msg_id: {'flags': flags_before}
+                                     for msg_id in indexed_ids})
+        event = {
+            'messages': event_message_ids,
+            'type': 'update_message_flags',
+            'flag': 'read',
+            'operation': 'add',
+            'all': False,
+        }
+
+        mocker.patch('zulipterminal.model.Model.update_rendered_view')
+        set_count = mocker.patch('zulipterminal.model.set_count')
+
+        model.update_message_flag_status(event)
+
+        changed_ids = set(indexed_ids) & set(event_message_ids)
+        for changed_id in changed_ids:
+            assert model.index['messages'][changed_id]['flags'] == flags_after
+        (model.update_rendered_view.
+         has_calls([mocker.call(changed_id) for changed_id in changed_ids]))
+
+        for unchanged_id in (set(indexed_ids) - set(event_message_ids)):
+            assert (model.index['messages'][unchanged_id]['flags'] ==
+                    flags_before)
+
+        set_count.assert_called_once_with(list(changed_ids),
+                                          self.controller, -1)
+
     @pytest.mark.parametrize('narrow, event, called', [
         # Not in PM Narrow
         ([], {}, False),

zulipterminal/model.py

@@ -287,7 +287,6 @@ def mark_message_ids_as_read(self, id_list: List[int]) -> None:
             'flag': 'read',
             'op': 'add',
         })
-        set_count(id_list, self.controller, -1)  # FIXME Update?
 
     def send_private_message(self, recipients: str,
                              content: str) -> bool:
@@ -815,7 +814,7 @@ def update_message_flag_status(self, event: Event) -> None:
 
         # TODO: Expand from 'starred' to also support 'read' flag changes?
         flag_to_change = event['flag']
-        if flag_to_change != 'starred':
+        if flag_to_change not in {'starred', 'read'}:
             return
 
         indexed_message_ids = set(self.index['messages'])
@@ -835,6 +834,10 @@ def update_message_flag_status(self, event: Event) -> None:
             self.index['messages'][message_id] = msg
             self.update_rendered_view(message_id)
 
+        if event['operation'] == 'add' and flag_to_change == 'read':
+            set_count(list(message_ids_to_mark & indexed_message_ids),
+                      self.controller, -1)
+
     def update_rendered_view(self, msg_id: int) -> None:
         # Update new content in the rendered view
         for msg_w in self.msg_list.log: