Validate message file upload limit

discord/http.py

@@ -173,6 +173,9 @@ def handle_message_parameters(
     if attachments is not MISSING and files is not MISSING:
         raise TypeError('Cannot mix attachments and files keyword arguments.')
 
+    if files is not MISSING and len(files) > 10:
+        raise ValueError('files has a maximum of 10 elements.')
+
     payload = {}
     if embeds is not MISSING:
         if len(embeds) > 10:

discord/webhook/async_.py

@@ -571,6 +571,9 @@ def interaction_message_response_params(
     if attachments is not MISSING and files is not MISSING:
         raise TypeError('Cannot mix attachments and files keyword arguments.')
 
+    if files is not MISSING and len(files) > 10:
+        raise ValueError('files has a maximum of 10 elements.')
+
     data: Optional[Dict[str, Any]] = {
         'tts': tts,
     }

tests/test_http.py

@@ -0,0 +1,53 @@
+"""
+The MIT License (MIT)
+
+Copyright (c) 2015-present Rapptz
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+"""
+
+from __future__ import annotations
+
+from io import BytesIO
+
+import discord
+import pytest
+
+from discord.http import handle_message_parameters
+from discord.webhook.async_ import interaction_message_response_params
+
+
+def make_file(index: int) -> discord.File:
+    return discord.File(BytesIO(b'test'), filename=f'test-{index}.txt')
+
+
+def test_handle_message_parameters_rejects_too_many_files():
+    files = [make_file(index) for index in range(11)]
+
+    with pytest.raises(ValueError, match='files has a maximum of 10 elements'):
+        handle_message_parameters(content='test', files=files)
+
+
+def test_interaction_message_response_params_rejects_too_many_files():
+    files = [make_file(index) for index in range(11)]
+
+    with pytest.raises(ValueError, match='files has a maximum of 10 elements'):
+        interaction_message_response_params(type=4, content='test', files=files)
+
+