core/stats: exclude contextmanagers from guess_stats

my/core/tests/auto_stats.py

@@ -1,11 +1,11 @@
 """
 Helper 'module' for test_guess_stats
 """
-
+from contextlib import contextmanager
 from dataclasses import dataclass
 from datetime import datetime, timedelta
 from pathlib import Path
-from typing import Iterable, Sequence
+from typing import Iterable, Sequence, Iterator
 
 
 @dataclass
@@ -28,3 +28,9 @@ def iter_data() -> Iterable[Item]:
     for path in inputs():
         for i in range(3):
             yield Item(id=str(i), dt=dt + timedelta(days=i), source=path)
+
+
+@contextmanager
+def some_contextmanager() -> Iterator[str]:
+    # this shouldn't end up in guess_stats because context manager is not a data provider
+    yield 'hello'