Add deque tests

tests/snippets/test_collections.py

@@ -0,0 +1,29 @@
+from collections import deque
+
+
+d = deque([0, 1, 2])
+
+d.append(1)
+d.appendleft(3)
+
+assert d == deque([3, 0, 1, 2, 1])
+
+assert d <= deque([4])
+
+assert d.copy() is not d
+
+d = deque([1, 2, 3], 5)
+
+d.extend([4, 5, 6])
+
+assert d == deque([2, 3, 4, 5, 6])
+
+d.remove(4)
+
+assert d == deque([2, 3, 5, 6])
+
+d.clear()
+
+assert d == deque()
+
+assert d == deque([], 4)