Move os.mkdir and addCleanup functions beginning of the testcases

Author: furkanonder

Lib/test/test_shelve.py

@@ -167,6 +167,9 @@ def test_default_protocol(self):
             self.assertEqual(s._protocol, pickle.DEFAULT_PROTOCOL)
 
     def test_custom_serializer_and_deserializer(self):
+        os.mkdir(self.dirname)
+        self.addCleanup(os_helper.rmtree, self.dirname)
+
         def serializer(obj, protocol):
             if isinstance(obj, (bytes, bytearray, str)):
                 if protocol == 5:
@@ -190,9 +193,6 @@ def deserializer(data):
                     f"Unsupported type for deserialization: {type(data)}"
                 )
 
-        os.mkdir(self.dirname)
-        self.addCleanup(os_helper.rmtree, self.dirname)
-
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             with self.subTest(proto=proto):
                 with shelve.open(
@@ -258,6 +258,8 @@ def deserializer(data):
 
     def test_custom_serializer_and_deserializer_bsd_db_shelf(self):
         berkeleydb = import_helper.import_module("berkeleydb")
+        os.mkdir(self.dirname)
+        self.addCleanup(os_helper.rmtree, self.dirname)
 
         def serializer(obj, protocol=None):
             data = obj.__class__.__name__
@@ -268,9 +270,6 @@ def serializer(obj, protocol=None):
         def deserializer(data):
             return data.decode("utf-8")
 
-        os.mkdir(self.dirname)
-        self.addCleanup(os_helper.rmtree, self.dirname)
-
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             with self.subTest(proto=5):
                 with shelve.BsdDbShelf(