Issue #26015: Added new tests for pickling iterators of mutable sequences.

1 files changed, 66 insertions, 24 deletions

diff --git a/Lib/test/test_list.py b/Lib/test/test_list.py
index 750d6cf..8f82ab5 100644
--- a/Lib/test/test_list.py
+++ b/Lib/test/test_list.py
@@ -72,34 +72,76 @@ class ListTest(list_tests.CommonTest):
         check(1000000)
 
     def test_iterator_pickle(self):
-        # Userlist iterators don't support pickling yet since
-        # they are based on generators.
-        data = self.type2test([4, 5, 6, 7])
+        orig = self.type2test([4, 5, 6, 7])
+        data = [10, 11, 12, 13, 14, 15]
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
-            it = itorg = iter(data)
-            d = pickle.dumps(it, proto)
-            it = pickle.loads(d)
-            self.assertEqual(type(itorg), type(it))
-            self.assertEqual(self.type2test(it), self.type2test(data))
-
-            it = pickle.loads(d)
-            next(it)
-            d = pickle.dumps(it, proto)
-            self.assertEqual(self.type2test(it), self.type2test(data)[1:])
+            # initial iterator
+            itorig = iter(orig)
+            d = pickle.dumps((itorig, orig), proto)
+            it, a = pickle.loads(d)
+            a[:] = data
+            self.assertEqual(type(it), type(itorig))
+            self.assertEqual(list(it), data)
+
+            # running iterator
+            next(itorig)
+            d = pickle.dumps((itorig, orig), proto)
+            it, a = pickle.loads(d)
+            a[:] = data
+            self.assertEqual(type(it), type(itorig))
+            self.assertEqual(list(it), data[1:])
+
+            # empty iterator
+            for i in range(1, len(orig)):
+                next(itorig)
+            d = pickle.dumps((itorig, orig), proto)
+            it, a = pickle.loads(d)
+            a[:] = data
+            self.assertEqual(type(it), type(itorig))
+            self.assertEqual(list(it), data[len(orig):])
+
+            # exhausted iterator
+            self.assertRaises(StopIteration, next, itorig)
+            d = pickle.dumps((itorig, orig), proto)
+            it, a = pickle.loads(d)
+            a[:] = data
+            self.assertEqual(list(it), [])
 
     def test_reversed_pickle(self):
-        data = self.type2test([4, 5, 6, 7])
+        orig = self.type2test([4, 5, 6, 7])
+        data = [10, 11, 12, 13, 14, 15]
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
-            it = itorg = reversed(data)
-            d = pickle.dumps(it, proto)
-            it = pickle.loads(d)
-            self.assertEqual(type(itorg), type(it))
-            self.assertEqual(self.type2test(it), self.type2test(reversed(data)))
-
-            it = pickle.loads(d)
-            next(it)
-            d = pickle.dumps(it, proto)
-            self.assertEqual(self.type2test(it), self.type2test(reversed(data))[1:])
+            # initial iterator
+            itorig = reversed(orig)
+            d = pickle.dumps((itorig, orig), proto)
+            it, a = pickle.loads(d)
+            a[:] = data
+            self.assertEqual(type(it), type(itorig))
+            self.assertEqual(list(it), data[len(orig)-1::-1])
+
+            # running iterator
+            next(itorig)
+            d = pickle.dumps((itorig, orig), proto)
+            it, a = pickle.loads(d)
+            a[:] = data
+            self.assertEqual(type(it), type(itorig))
+            self.assertEqual(list(it), data[len(orig)-2::-1])
+
+            # empty iterator
+            for i in range(1, len(orig)):
+                next(itorig)
+            d = pickle.dumps((itorig, orig), proto)
+            it, a = pickle.loads(d)
+            a[:] = data
+            self.assertEqual(type(it), type(itorig))
+            self.assertEqual(list(it), [])
+
+            # exhausted iterator
+            self.assertRaises(StopIteration, next, itorig)
+            d = pickle.dumps((itorig, orig), proto)
+            it, a = pickle.loads(d)
+            a[:] = data
+            self.assertEqual(list(it), [])
 
     def test_no_comdat_folding(self):
         # Issue 8847: In the PGO build, the MSVC linker's COMDAT folding