MOTOR-1183 Typing issue in core.pyi causing MyPy error for to_list … (#…

…226)

Co-authored-by: Sergi Pous <spous@objectvideo.com>
Co-authored-by: Steven Silvester <steven.silvester@ieee.org>

motor/core.pyi

@@ -16,6 +16,7 @@
 
 from __future__ import annotations
 
+from asyncio import Future
 from typing import (
     Any,
     Awaitable,
@@ -654,11 +655,11 @@ class AgnosticBaseCursor(AgnosticBase):
     async def __aexit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> Any: ...
     def _get_more(self) -> int: ...
     @property
-    def fetch_next(self) -> Any: ...
+    def fetch_next(self) -> Future[Any]: ...
     def next_object(self) -> Any: ...
     def each(self, callback: Callable) -> None: ...
     def _each_got_more(self, callback: Callable, future: Any) -> None: ...
-    def to_list(self, length: int) -> List: ...
+    def to_list(self, length: int) -> Future[List]: ...
     def _to_list(self, length: int, the_list: List, future: Any, get_more_result: Any) -> None: ...
     def get_io_loop(self) -> Any: ...
     def batch_size(self, batch_size: int) -> AgnosticBaseCursor: ...

test/test_typing.py

@@ -17,7 +17,7 @@
 """
 import unittest
 from test.asyncio_tests import AsyncIOTestCase, asyncio_test
-from typing import TYPE_CHECKING, Any, AsyncIterable, Dict, List, Union
+from typing import TYPE_CHECKING, Any, Dict, List, Union
 
 from bson import CodecOptions
 from bson.raw_bson import RawBSONDocument
@@ -80,13 +80,10 @@ async def test_insert_find(self) -> None:
             self.assertEqual(result2.inserted_id, result.inserted_id)
 
     @asyncio_test
-    async def test_cursor_iterable(self) -> None:
-        async def to_list(iterable: AsyncIterable[Dict[str, Any]]) -> List[Dict[str, Any]]:
-            return [gen async for gen in iterable]
-
+    async def test_cursor_to_list(self) -> None:
         await self.collection.insert_one({})
         cursor = self.collection.find()
-        docs = await to_list(cursor)
+        docs = await cursor.to_list(None)
         self.assertTrue(docs)
 
     @only_type_check