Issue 13177: Make tracebacks more readable by avoiding chained exceptions in the lru_cache.
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 7d11b53..270cab0 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -655,6 +655,22 @@
self.assertEqual(fib.cache_info(),
functools._CacheInfo(hits=0, misses=0, maxsize=None, currsize=0))
+ def test_lru_with_exceptions(self):
+ # Verify that user_function exceptions get passed through without
+ # creating a hard-to-read chained exception.
+ # http://bugs.python.org/issue13177
+ for maxsize in (None, 100):
+ @functools.lru_cache(maxsize)
+ def func(i):
+ return 'abc'[i]
+ self.assertEqual(func(0), 'a')
+ with self.assertRaises(IndexError) as cm:
+ func(15)
+ self.assertIsNone(cm.exception.__context__)
+ # Verify that the previous exception did not result in a cached entry
+ with self.assertRaises(IndexError):
+ func(15)
+
def test_main(verbose=None):
test_classes = (
TestPartial,