'Test the String incrementation sequence'

def test_sequence_string(self):

    from boto.sdb.db.sequence import Sequence, increment_string
    s = Sequence(fnc=increment_string)
    self.sequences.append(s)
    assert (s.val == 'A')
    assert (s.next() == 'B')
    s.val = 'Z'
    assert (s.val == 'Z')
    assert (s.next() == 'AA')
