Properly close all streams

test/test_prototype_datasets_builtin.py

@@ -122,12 +122,15 @@ def log_session_streams(self):
     @parametrize_dataset_mocks(DATASET_MOCKS)
     def test_stream_closing(self, log_session_streams, dataset_mock, config):
         def make_msg_and_close(head):
+            unclosed_stream_reprs = []
             unclosed_streams = []
             for stream in StreamWrapper.session_streams.keys():
-                unclosed_streams.append(repr(stream.file_obj))
+                unclosed_stream_reprs.append(repr(stream.file_obj))
+                unclosed_streams.append(stream)
+            for stream in unclosed_streams:
                 stream.close()
-            unclosed_streams = "\n".join(unclosed_streams)
-            return f"{head}\n\n{unclosed_streams}"
+            unclosed_stream_reprs = "\n".join(unclosed_stream_reprs)
+            return f"{head}\n\n{unclosed_stream_reprs}"
 
         if StreamWrapper.session_streams:
             raise pytest.UsageError(make_msg_and_close("A previous test did not close the following streams:"))