test: re-enable stable concurrent transaction unit tests, but skip StreamedResultSet variants since Pytest >=8 unhandled thread exceptions explicitly bubble up from lazy evaluation races

Author: aseering

test_finally.py

@@ -253,8 +253,13 @@ def _execute_sql_helper(
         ]
         for i in range(len(result_sets)):
             result_sets[i].values.extend(VALUE_PBS[i])
-        iterator = _MockIterator(*result_sets)
-        api.execute_streaming_sql.return_value = iterator
+
+        def _make_iterator(*args, **kwargs):
+            from copy import deepcopy
+
+            return _MockIterator(*deepcopy(result_sets))
+
+        api.execute_streaming_sql.side_effect = _make_iterator
         transaction._execute_sql_request_count = sql_count
         transaction._read_request_count = count
 
@@ -360,7 +365,12 @@ def _read_helper(
         for i in range(len(result_sets)):
             result_sets[i].values.extend(VALUE_PBS[i])
 
-        api.streaming_read.return_value = _MockIterator(*result_sets)
+        def _make_iterator(*args, **kwargs):
+            from copy import deepcopy
+
+            return _MockIterator(*deepcopy(result_sets))
+
+        api.streaming_read.side_effect = _make_iterator
         transaction._read_request_count = count
 
         if partition is not None:  # 'limit' and 'partition' incompatible
@@ -957,9 +967,6 @@ def test_transaction_should_use_transaction_id_returned_by_first_batch_update(se
             timeout=TIMEOUT,
         )
 
-    @pytest.mark.skip(
-        reason="Inherently flaky, relies on thread crash swallowing in older Pytest"
-    )
     def test_transaction_for_concurrent_statement_should_begin_one_transaction_with_execute_update(
         self,
     ):
@@ -1033,9 +1040,6 @@ def test_transaction_for_concurrent_statement_should_begin_one_transaction_with_
         self.assertEqual(api.execute_sql.call_count, 2)
         self.assertEqual(api.execute_batch_dml.call_count, 1)
 
-    @pytest.mark.skip(
-        reason="Inherently flaky, relies on thread crash swallowing in older Pytest"
-    )
     def test_transaction_for_concurrent_statement_should_begin_one_transaction_with_batch_update(
         self,
     ):
@@ -1103,7 +1107,7 @@ def test_transaction_for_concurrent_statement_should_begin_one_transaction_with_
         self.assertEqual(actual_id_suffixes, expected_id_suffixes)
 
     @pytest.mark.skip(
-        reason="Inherently flaky, relies on thread crash swallowing in older Pytest"
+        reason="Inherently flaky: concurrent StreamedResultSet requests race inline begins due to lazy evaluation"
     )
     def test_transaction_for_concurrent_statement_should_begin_one_transaction_with_read(
         self,
@@ -1179,7 +1183,7 @@ def test_transaction_for_concurrent_statement_should_begin_one_transaction_with_
         self.assertEqual(actual_id_suffixes, expected_id_suffixes)
 
     @pytest.mark.skip(
-        reason="Inherently flaky, relies on thread crash swallowing in older Pytest"
+        reason="Inherently flaky: concurrent StreamedResultSet requests race inline begins due to lazy evaluation"
     )
     def test_transaction_for_concurrent_statement_should_begin_one_transaction_with_query(
         self,