Remove redundant pickle tests

Remove also DictKey (use Object instead).

Author: vstinner

Lib/test/picklecommon.py

@@ -243,9 +243,6 @@ class MyUnicode(str):
     class MyUnicode(unicode):
         sample = unicode(r"hello \u1234", "raw-unicode-escape")
 
-class DictKey:
-    pass
-
 class MyTuple(tuple):
     sample = (1, 2, 3)
 

Lib/test/pickletester.py

@@ -2913,7 +2913,7 @@ def test_recursive_frozenset_subclass_and_inst(self):
 
     def _test_recursive_collection_in_key(self, factory, minprotocol=0):
         protocols = range(minprotocol, pickle.HIGHEST_PROTOCOL + 1)
-        key = DictKey()
+        key = Object()
         o = factory({key: 1})
         key.attr = o
         for proto in protocols:
@@ -2924,12 +2924,6 @@ def _test_recursive_collection_in_key(self, factory, minprotocol=0):
                 self.assertEqual(len(keys), 1)
                 self.assertIs(keys[0].attr, x)
 
-    def test_recursive_dict_in_key(self):
-        self._test_recursive_collection_in_key(dict)
-
-    def test_recursive_dict_subclass_in_key(self):
-        self._test_recursive_collection_in_key(MyDict)
-
     def test_recursive_frozendict_in_key(self):
         self._test_recursive_collection_in_key(frozendict, minprotocol=2)
 
@@ -2947,12 +2941,6 @@ def _test_recursive_collection_in_value(self, factory, minprotocol=0):
                 self.assertEqual(len(x['key']), 1)
                 self.assertIs(x['key'][0], x)
 
-    def test_recursive_dict_in_value(self):
-        self._test_recursive_collection_in_value(dict)
-
-    def test_recursive_dict_subclass_in_value(self):
-        self._test_recursive_collection_in_value(MyDict)
-
     def test_recursive_frozendict_in_value(self):
         self._test_recursive_collection_in_value(frozendict, minprotocol=2)