def test_init_empty(self): """BaseUsage should init with empty freqs""" b = BaseUsage() self.assertEqual(len(b), 4) for nt in 'UTACGutacg': assert nt in b self.assertEqual(b[nt], 0) for nt in 'UCAG': assert nt in b.keys() items = list(iter(b)) items.sort() self.assertEqual(items, ['A', 'C', 'G', 'U'])