Make test code for the non-pandas case a bit more explicit

Author: roberthdevries

pandas/tests/io/pytables/test_store.py

@@ -318,7 +318,7 @@ class Table3(tables.IsDescription):
                 assert len(store.keys(kind="tables")) == 3
                 expected = {"/group/table1", "/group/table2", "/group/table3"}
                 assert set(store.keys(kind="tables")) == expected
-                assert set(store) == set()
+                assert set(store.keys(kind="pandas")) == set()
 
     def test_keys_ignore_hdf_softlink(self, setup_path):