Close the file in test_stats_file_failed().

tests/test_feedexport.py

@@ -478,9 +478,14 @@ class TestFeedExport(TestFeedExportBase):
             },
         }
         crawler = get_crawler(ItemSpider, settings)
+
+        def store(file: IO[bytes]) -> None:
+            file.close()
+            raise KeyError("foo")
+
         with mock.patch(
             "scrapy.extensions.feedexport.FileFeedStorage.store",
-            side_effect=KeyError("foo"),  # TODO this needs file.close()
+            side_effect=store,
         ):
             yield crawler.crawl(mockserver=self.mockserver)
         assert "feedexport/failed_count/FileFeedStorage" in crawler.stats.get_stats()