add test for pool

Author: wlwlwlzhang

test/test_dataset.py

@@ -621,6 +621,9 @@ def insert_data():
                 [thread.start() for thread in threads]
                 [thread.join() for thread in threads]
                 t = db[table_name].count()
+                with db as tx:
+                    if table_name in tx:
+                        tx[table_name].drop()
                 assert t == target_num + 1, t
             except SQLAlchemyError as e:
                 if "timeout expired" in str(e) or "Connection refused" in str(e):