Issue #26492: Added additional tests for exhausted iterators of mutable sequences.

3 files changed, 32 insertions, 0 deletions

diff --git a/Lib/test/list_tests.py b/Lib/test/list_tests.py
index b8d6d6b..ed606db 100644
--- a/Lib/test/list_tests.py
+++ b/Lib/test/list_tests.py
@@ -532,3 +532,14 @@ class CommonTest(seq_tests.CommonTest):
             def __iter__(self):
                 raise KeyboardInterrupt
         self.assertRaises(KeyboardInterrupt, list, F())
+
+    def test_exhausted_iterator(self):
+        a = self.type2test([1, 2, 3])
+        exhit = iter(a)
+        empit = iter(a)
+        for x in exhit:  # exhaust the iterator
+            next(empit)  # not exhausted
+        a.append(9)
+        self.assertEqual(list(exhit), [])
+        self.assertEqual(list(empit), [9])
+        self.assertEqual(a, self.type2test([1, 2, 3, 9]))
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index 82ad451..bdcb88a 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -900,6 +900,16 @@ class ByteArrayTest(BaseBytesTest):
         # PyByteArray_AS_STRING() C macro.
         self.assertRaises(ValueError, int, bytearray(b''))
 
+    def test_exhausted_iterator(self):
+        a = self.type2test([1, 2, 3])
+        exhit = iter(a)
+        empit = iter(a)
+        for x in exhit:  # exhaust the iterator
+            next(empit)  # not exhausted
+        a.append(9)
+        self.assertEqual(list(exhit), [])
+        self.assertEqual(list(empit), [9])
+        self.assertEqual(a, self.type2test([1, 2, 3, 9]))
 
 class AssortedBytesTest(unittest.TestCase):
     #
diff --git a/Lib/test/test_iter.py b/Lib/test/test_iter.py
index 4495fa1..cc20865 100644
--- a/Lib/test/test_iter.py
+++ b/Lib/test/test_iter.py
@@ -122,6 +122,17 @@ class TestCase(unittest.TestCase):
     def test_seq_class_iter(self):
         self.check_iterator(iter(SequenceClass(10)), range(10))
 
+    def test_mutating_seq_class_exhausted_iter(self):
+        a = SequenceClass(5)
+        exhit = iter(a)
+        empit = iter(a)
+        for x in exhit:  # exhaust the iterator
+            next(empit)  # not exhausted
+        a.n = 7
+        self.assertEqual(list(exhit), [])
+        self.assertEqual(list(empit), [5, 6])
+        self.assertEqual(list(a), [0, 1, 2, 3, 4, 5, 6])
+
     # Test a new_style class with __iter__ but no next() method
     def test_new_style_iter_class(self):
         class IterClass(object):