Add error-checking to namedtuple's _replace() method.

1 files changed, 7 insertions, 0 deletions

diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index c17b76dffe..dd9982af3c 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -55,6 +55,13 @@ class TestNamedTuple(unittest.TestCase):
         self.assertEqual(p._replace(x=1), (1, 22))                          # test _replace method
         self.assertEqual(p._asdict(), dict(x=11, y=22))                     # test _asdict method
 
+        try:
+            p._replace(x=1, error=2)
+        except ValueError:
+            pass
+        else:
+            self._fail('Did not detect an incorrect fieldname')
+
         # verify that field string can have commas
         Point = namedtuple('Point', 'x, y')
         p = Point(x=11, y=22)