def test_three_members(self):
pairs_gen = pairs([1, 2, 3])
self.assertEquals((1, 2), pairs_gen.next())
self.assertEquals((3, 0), pairs_gen.next())
self.assertRaises(StopIteration, pairs_gen.next)
def test_empty(self):
self.assertRaises(StopIteration, pairs([]).next)
def test_one_member(self):
pairs_gen = pairs([1])
self.assertEquals((1, 0), pairs_gen.next())
self.assertRaises(StopIteration, pairs_gen.next)
