diff --git a/scrapy/core/engine.py b/scrapy/core/engine.py
index f577b481b..973ae3258 100644
--- a/scrapy/core/engine.py
+++ b/scrapy/core/engine.py
@@ -641,6 +641,7 @@ class ExecutionEngine:
             extra={"spider": self.spider},
         )
 
+    # pylint: disable=too-many-statements
     async def close_spider_async(  # noqa: PLR0912, PLR0915
         self,
         *,
diff --git a/scrapy/utils/_stopmode.py b/scrapy/utils/_stopmode.py
index afb7b4768..05b64ec9a 100644
--- a/scrapy/utils/_stopmode.py
+++ b/scrapy/utils/_stopmode.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import Literal, cast
+from typing import Literal
 
 StopMode = Literal["graceful", "fast", "force"]
 
@@ -18,10 +18,9 @@ def normalize_stop_mode(mode: StopMode | None, *, allow_force: bool = True) -> S
         raise ValueError(
             f"Unknown stop mode {mode!r}. Expected one of: graceful, fast, force"
         )
-    normalized = cast("StopMode", mode)
-    if normalized == "force" and not allow_force:
+    if mode == "force" and not allow_force:
         raise ValueError("The force stop mode is not supported in this context")
-    return normalized
+    return mode
 
 
 def max_stop_mode(mode1: StopMode, mode2: StopMode) -> StopMode:
diff --git a/tests/test_core_downloader.py b/tests/test_core_downloader.py
index c3ba4125c..aba1541e0 100644
--- a/tests/test_core_downloader.py
+++ b/tests/test_core_downloader.py
@@ -31,6 +31,7 @@ from tests.utils.decorators import coroutine_test
 
 if TYPE_CHECKING:
     from twisted.internet.ssl import ContextFactory
+    from twisted.python.failure import Failure
     from twisted.web.iweb import IBodyProducer
 
 
@@ -220,7 +221,7 @@ async def test_stop_async_drops_queued_requests() -> None:
 
     request = Request("https://example.com")
     queue_dfd: Deferred = Deferred()
-    failures = []
+    failures: list[Failure] = []
     queue_dfd.addErrback(failures.append)
     slot.queue.append((request, queue_dfd))
 
diff --git a/tests/test_crawler.py b/tests/test_crawler.py
index 6ae097664..c4c28114c 100644
--- a/tests/test_crawler.py
+++ b/tests/test_crawler.py
@@ -794,7 +794,7 @@ async def test_deprecated_crawler_stop() -> None:
 async def test_crawler_stop_async_invalid_mode() -> None:
     crawler = get_crawler(DefaultSpider)
     with pytest.raises(ValueError, match=r"Unknown stop mode"):
-        await crawler.stop_async(mode="invalid")
+        await crawler.stop_async(mode="invalid")  # type: ignore[arg-type]
 
 
 @coroutine_test
@@ -809,12 +809,13 @@ async def test_crawler_force_stop_falls_back_to_fast(
         async def stop_async(self, *, mode: str = "graceful") -> None:
             self.called_mode = mode
 
-    crawler.engine = DummyEngine()  # type: ignore[assignment]
+    dummy_engine = DummyEngine()
+    crawler.engine = dummy_engine  # type: ignore[assignment]
 
     with caplog.at_level(logging.WARNING):
         await crawler.stop_async(mode="force")
 
-    assert crawler.engine.called_mode == "fast"
+    assert dummy_engine.called_mode == "fast"
     assert "Falling back to fast stop" in caplog.text
 
 
diff --git a/tests/test_engine.py b/tests/test_engine.py
index 78e52d7db..5900695af 100644
--- a/tests/test_engine.py
+++ b/tests/test_engine.py
@@ -8,7 +8,7 @@ from collections import defaultdict
 from dataclasses import dataclass
 from logging import DEBUG
 from typing import TYPE_CHECKING, Any, cast
-from unittest.mock import Mock, call
+from unittest.mock import Mock, call, patch
 from urllib.parse import urlparse
 
 import attr
@@ -784,9 +784,8 @@ class TestEngineCloseSpider:
             calls += 1
             return 3
 
-        engine.downloader.stop_async = fast_stop_downloader
-
-        await engine.close_spider_async(mode="fast")
+        with patch.object(engine.downloader, "stop_async", fast_stop_downloader):
+            await engine.close_spider_async(mode="fast")
 
         assert calls == 1
         assert crawler.stats