tests: Fix clumsy narrow test.

We now explicitly write messages to three different streams,
as well a DM, to make sure each narrow result filters out
all the noise.

zerver/tests/test_message_fetch.py

@@ -51,6 +51,7 @@ from zerver.models import (
     Attachment,
     Message,
     Realm,
+    Recipient,
     Subscription,
     UserMessage,
     UserProfile,
@@ -2280,30 +2281,45 @@ class GetOldMessagesTest(ZulipTestCase):
         self.assertEqual(new_message["flags"], ["mentioned"])
 
     def test_get_messages_with_narrow_stream(self) -> None:
-        """
-        A request for old messages with a narrow by stream only returns
-        messages for that stream.
-        """
-        self.login("hamlet")
-        # We need to subscribe to a stream and then send a message to
-        # it to ensure that we actually have a stream message in this
-        # narrow view.
-        self.subscribe(self.example_user("hamlet"), "Scotland")
-        self.send_stream_message(self.example_user("hamlet"), "Scotland")
-        messages = get_user_messages(self.example_user("hamlet"))
+        hamlet = self.example_user("hamlet")
+        self.login_user(hamlet)
+        realm = hamlet.realm
+
+        num_messages_per_stream = 5
+        stream_names = ["Scotland", "Verona", "Venice"]
+
+        def send_messages_to_all_streams() -> None:
+            Message.objects.filter(recipient__type=Recipient.STREAM).delete()
+            for stream_name in stream_names:
+                self.subscribe(hamlet, stream_name)
+                for i in range(num_messages_per_stream):
+                    message_id = self.send_stream_message(hamlet, stream_name, content=f"test {i}")
+                    message = Message.objects.get(id=message_id)
+                    self.assertEqual(get_display_recipient(message.recipient), stream_name)
+
+        send_messages_to_all_streams()
+
+        self.send_personal_message(hamlet, hamlet)
+
+        messages = get_user_messages(hamlet)
         stream_messages = [msg for msg in messages if msg.is_stream_message()]
-        stream_name = get_display_recipient(stream_messages[0].recipient)
-        assert isinstance(stream_name, str)
-        stream_id = get_stream(stream_name, stream_messages[0].get_realm()).id
-        stream_recipient_id = stream_messages[0].recipient.id
+        self.assertGreater(len(messages), len(stream_messages))
+        self.assert_length(stream_messages, num_messages_per_stream * len(stream_names))
 
-        for operand in [stream_name, stream_id]:
-            narrow = [dict(operator="stream", operand=operand)]
-            result = self.get_and_check_messages(dict(narrow=orjson.dumps(narrow).decode()))
+        for stream_name in stream_names:
+            stream = get_stream(stream_name, realm)
+            for operand in [stream.name, stream.id]:
+                narrow = [dict(operator="stream", operand=operand)]
+                result = self.get_and_check_messages(
+                    dict(narrow=orjson.dumps(narrow).decode(), num_after=100)
+                )
+                fetched_messages: List[Dict[str, object]] = result["messages"]
+                self.assert_length(fetched_messages, num_messages_per_stream)
 
-            for message in result["messages"]:
-                self.assertEqual(message["type"], "stream")
-                self.assertEqual(message["recipient_id"], stream_recipient_id)
+                for message_dict in fetched_messages:
+                    self.assertEqual(message_dict["type"], "stream")
+                    self.assertEqual(message_dict["display_recipient"], stream_name)
+                    self.assertEqual(message_dict["recipient_id"], stream.recipient_id)
 
     def test_get_visible_messages_with_narrow_stream(self) -> None:
         self.login("hamlet")