1 files changed, 9 insertions, 0 deletions
diff --git a/Lib/test/string_tests.py b/Lib/test/string_tests.py
index 4335965b36..c8ed07cf60 100644
--- a/Lib/test/string_tests.py
+++ b/Lib/test/string_tests.py
@@ -80,6 +80,15 @@ class CommonTest(unittest.TestCase):
         args = self.fixtype(args)
         getattr(object, methodname)(*args)
 
+    def test_hash(self):
+        # SF bug 1054139:  += optimization was not invalidating cached hash value
+        a = self.type2test('DNSSEC')
+        b = self.type2test('')
+        for c in a:
+            b += c
+            hash(b)
+        self.assertEqual(hash(a), hash(b))
+
     def test_capitalize(self):
         self.checkequal(' hello ', ' hello ', 'capitalize')
         self.checkequal('Hello ', 'Hello ','capitalize')