utils/messages: Add a dummy message for empty narrows.

Tests updated.

Co-authored-by: Sumanth V Rao <[email protected]>

tests/ui_tools/test_messages.py

@@ -48,6 +48,7 @@ def test_init(self, mocker, message_type, set_fields):
             display_recipient=[
                 {"id": 7, "email": "[email protected]", "full_name": "Boo is awesome"}
             ],
+            id=457823,
             stream_id=5,
             subject="hi",
             sender_email="[email protected]",
@@ -71,6 +72,7 @@ def test_private_message_to_self(self, mocker):
             display_recipient=[
                 {"full_name": "Foo Foo", "email": "[email protected]", "id": None}
             ],
+            id=457823,
             sender_id=9,
             content="<p> self message. </p>",
             sender_full_name="Foo Foo",
@@ -82,6 +84,7 @@ def test_private_message_to_self(self, mocker):
             MODULE + ".MessageBox._is_private_message_to_self", return_value=True
         )
         mocker.patch.object(MessageBox, "main_view")
+
         msg_box = MessageBox(message, self.model, None)
 
         assert msg_box.recipient_emails == ["[email protected]"]
@@ -753,6 +756,7 @@ def test_main_view(self, mocker, message, last_message):
                 "color": "#bd6",
             },
         }
+        self.model.controller.is_in_empty_narrow = False
         MessageBox(message, self.model, last_message)
 
     @pytest.mark.parametrize(
@@ -1149,8 +1153,11 @@ def test_main_view_compact_output(
     ):
         message_fixture.update({"id": 4})
         varied_message = dict(message_fixture, **to_vary_in_each_message)
+        self.model.controller.is_in_empty_narrow = False
         msg_box = MessageBox(varied_message, self.model, varied_message)
+
         view_components = msg_box.main_view()
+
         assert len(view_components) == 1
         assert isinstance(view_components[0], Padding)
 
@@ -1160,7 +1167,9 @@ def test_main_view_generates_EDITED_label(
         messages = messages_successful_response["messages"]
         for message in messages:
             self.model.index["edited_messages"].add(message["id"])
+            self.model.controller.is_in_empty_narrow = False
             msg_box = MessageBox(message, self.model, message)
+
             view_components = msg_box.main_view()
 
             label = view_components[0].original_widget.contents[0]
@@ -1186,6 +1195,7 @@ def test_update_message_author_status(
     ):
         message = message_fixture
         last_msg = dict(message, **to_vary_in_last_message)
+        self.model.controller.is_in_empty_narrow = False
 
         msg_box = MessageBox(message, self.model, last_msg)
 
@@ -1389,6 +1399,7 @@ def test_keypress_EDIT_MESSAGE(
             to_vary_in_each_message["subject"] = ""
         varied_message = dict(message_fixture, **to_vary_in_each_message)
         message_type = varied_message["type"]
+        self.model.controller.is_in_empty_narrow = False
         msg_box = MessageBox(varied_message, self.model, message_fixture)
         size = widget_size(msg_box)
         msg_box.model.user_id = 1

zulipterminal/ui_tools/messages.py

@@ -82,8 +82,10 @@ def __init__(self, message: Message, model: "Model", last_message: Any) -> None:
             self.stream_id = self.message["stream_id"]
             self.topic_name = self.message["subject"]
         else:
-            self.email = self.message["sender_email"]
-            self.user_id = self.message["sender_id"]
+            # Get sender details only for non-empty narrows
+            if self.message.get("id") is not None:
+                self.email = self.message["sender_email"]
+                self.user_id = self.message["sender_id"]
 
             if self._is_private_message_to_self():
                 recipient = self.message["display_recipient"][0]

zulipterminal/ui_tools/utils.py

@@ -29,6 +29,46 @@ def create_msg_box_list(
     focus_msg = None
     last_msg = last_message
     muted_msgs = 0  # No of messages that are muted.
+
+    # Add a dummy message if no new or old messages are found
+    if not message_list and not last_msg:
+        message_type = "stream" if model.stream_id is not None else "private"
+        dummy_message = {
+            "id": None,
+            "content": (
+                "No search hits" if model.is_search_narrow() else "No messages here"
+            ),
+            "is_me_message": False,
+            "flags": ["read"],
+            "reactions": [],
+            "type": message_type,
+            "stream_id": model.stream_id if message_type == "stream" else None,
+            "stream_name": model.stream_dict[model.stream_id]["name"]
+            if message_type == "stream"
+            else None,
+            "subject": next(
+                (subnarrow[1] for subnarrow in model.narrow if subnarrow[0] == "topic"),
+                "No topics in channel",
+            )
+            if message_type == "stream"
+            else None,
+            "display_recipient": (
+                model.stream_dict[model.stream_id]["name"]
+                if message_type == "stream"
+                else [
+                    {
+                        "email": model.user_id_email_dict[recipient_id],
+                        "full_name": model.user_dict[
+                            model.user_id_email_dict[recipient_id]
+                        ]["full_name"],
+                        "id": recipient_id,
+                    }
+                    for recipient_id in model.recipients
+                ]
+            ),
+        }
+        message_list.append(dummy_message)
+
     for msg in message_list:
         if is_unsubscribed_message(msg, model):
             continue