Fix get(_input)_users in ChatAction with no service msg

telethon/events/chataction.py

@@ -381,7 +381,8 @@ class ChatAction(EventBuilder):
             if not self._user_ids:
                 return []
 
-            if self._users is None or len(self._users) != len(self._user_ids):
+            # Note: we access the property first so that it fills if needed
+            if (self.users is None or len(self._users) != len(self._user_ids)) and self.action_message:
                 await self.action_message._reload_message()
                 self._users = [
                     u for u in self.action_message.action_entities
@@ -397,19 +398,31 @@ class ChatAction(EventBuilder):
             if self._input_users is None and self._user_ids:
                 self._input_users = []
                 for user_id in self._user_ids:
+                    # First try to get it from our entities
+                    try:
+                        self._input_users.append(utils.get_input_peer(self._entities[user_id]))
+                        continue
+                    except (KeyError, TypeError) as e:
+                        pass
+
+                    # If missing, try from the entity cache
                     try:
                         self._input_users.append(self._client._entity_cache[user_id])
+                        continue
                     except KeyError:
                         pass
+
             return self._input_users or []
 
         async def get_input_users(self):
             """
             Returns `input_users` but will make an API call if necessary.
             """
-            self._input_users = None
-            if self._input_users is None:
-                await self.action_message._reload_message()
+            if not self._user_ids:
+                return []
+
+            # Note: we access the property first so that it fills if needed
+            if (self.input_users is None or len(self._input_users) != len(self._user_ids)) and self.action_message:
                 self._input_users = [
                     utils.get_input_peer(u)
                     for u in self.action_message.action_entities

tests/telethon/events/test_chataction.py

@@ -0,0 +1,67 @@
+import pytest
+
+from telethon import TelegramClient, events, types, utils
+
+
+def get_client():
+    return TelegramClient(None, 1, '1')
+
+
+def get_user_456():
+    return types.User(
+        id=456,
+        access_hash=789,
+        first_name='User 123'
+    )
+
+
+@pytest.mark.asyncio
+async def test_get_input_users_no_action_message_no_entities():
+    event = events.ChatAction.build(types.UpdateChatParticipantDelete(
+        chat_id=123,
+        user_id=456,
+        version=1
+    ))
+    event._set_client(get_client())
+
+    assert await event.get_input_users() == []
+
+
+@pytest.mark.asyncio
+async def test_get_input_users_no_action_message():
+    user = get_user_456()
+    event = events.ChatAction.build(types.UpdateChatParticipantDelete(
+        chat_id=123,
+        user_id=456,
+        version=1
+    ))
+    event._set_client(get_client())
+    event._entities[user.id] = user
+
+    assert await event.get_input_users() == [utils.get_input_peer(user)]
+
+
+@pytest.mark.asyncio
+async def test_get_users_no_action_message_no_entities():
+    event = events.ChatAction.build(types.UpdateChatParticipantDelete(
+        chat_id=123,
+        user_id=456,
+        version=1
+    ))
+    event._set_client(get_client())
+
+    assert await event.get_users() == []
+
+
+@pytest.mark.asyncio
+async def test_get_users_no_action_message():
+    user = get_user_456()
+    event = events.ChatAction.build(types.UpdateChatParticipantDelete(
+        chat_id=123,
+        user_id=456,
+        version=1
+    ))
+    event._set_client(get_client())
+    event._entities[user.id] = user
+
+    assert await event.get_users() == [user]