bpo-27141: Fix collections.UserList and UserDict shallow copy. (GH-4094)

1 files changed, 24 insertions, 0 deletions

diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 1f619bcdac..e2d04d5b47 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -37,6 +37,20 @@ class TestUserObjects(unittest.TestCase):
                 b=b.__name__,
             ),
         )
+
+    def _copy_test(self, obj):
+        # Test internal copy
+        obj_copy = obj.copy()
+        self.assertIsNot(obj.data, obj_copy.data)
+        self.assertEqual(obj.data, obj_copy.data)
+
+        # Test copy.copy
+        obj.test = [1234]  # Make sure instance vars are also copied.
+        obj_copy = copy.copy(obj)
+        self.assertIsNot(obj.data, obj_copy.data)
+        self.assertEqual(obj.data, obj_copy.data)
+        self.assertIs(obj.test, obj_copy.test)
+
     def test_str_protocol(self):
         self._superset_test(UserString, str)
 
@@ -46,6 +60,16 @@ class TestUserObjects(unittest.TestCase):
     def test_dict_protocol(self):
         self._superset_test(UserDict, dict)
 
+    def test_list_copy(self):
+        obj = UserList()
+        obj.append(123)
+        self._copy_test(obj)
+
+    def test_dict_copy(self):
+        obj = UserDict()
+        obj[123] = "abc"
+        self._copy_test(obj)
+
 
 ################################################################################
 ### ChainMap (helper class for configparser and the string module)