Add count() method to collections.deque().

1 files changed, 24 insertions, 0 deletions

diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index a2f5fae..17d724c 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -114,6 +114,30 @@ class TestBasic(unittest.TestCase):
             d = deque('abc')
             d.maxlen = 10
 
+    def test_count(self):
+        for s in ('', 'abracadabra', 'simsalabim'*500+'abc'):
+            s = list(s)
+            d = deque(s)
+            for letter in 'abcdefghijklmnopqrstuvwxyz':
+                self.assertEqual(s.count(letter), d.count(letter), (s, d, letter))
+        self.assertRaises(TypeError, d.count)       # too few args
+        self.assertRaises(TypeError, d.count, 1, 2) # too many args
+        class BadCompare:
+            def __eq__(self, other):
+                raise ArithmeticError
+        d = deque([1, 2, BadCompare(), 3])
+        self.assertRaises(ArithmeticError, d.count, 2)
+        d = deque([1, 2, 3])
+        self.assertRaises(ArithmeticError, d.count, BadCompare())
+        class MutatingCompare:
+            def __eq__(self, other):
+                self.d.pop()
+                return True
+        m = MutatingCompare()
+        d = deque([1, 2, 3, m, 4, 5])
+        m.d = d
+        self.assertRaises(RuntimeError, d.count, 3)
+
     def test_comparisons(self):
         d = deque('xabc'); d.popleft()
         for e in [d, deque('abc'), deque('ab'), deque(), list(d)]: