itertools: test_itertools.py: Add tests cycle().

itertools/test_itertools.py

@@ -9,3 +9,6 @@ def g():
         yield 123
 
 assert list(itertools.islice(g(), 5)) == [123, 123, 123, 123, 123]
+
+assert list(itertools.islice(itertools.cycle([1, 2, 3]), 10)) == [1, 2, 3, 1, 2, 3, 1, 2, 3, 1]
+assert list(itertools.islice(itertools.cycle(reversed([1, 2, 3])), 7)) == [3, 2, 1, 3, 2, 1, 3]