def test_cannot_peak_beyond_specified_lookahead(self):
peaker = Peaker((x for x in 'abcd'), lookahead=1)
with self.assertRaises(Exception):
peaker.peak(lookahead=3)
def test_peak_doesnt_move_stream_forward(self):
generator = cycle('abc')
peaker = Peaker(stream=generator)
self.assertEqual(peaker.peak(), 'a')
self.assertEqual(peaker.peak(), 'a')
def test_peaker_can_have_n_lookahead(self):
peaker = Peaker((x for x in 'abcd'), lookahead=3)
self.assertEqual(peaker.peak(lookahead=1), 'a')
self.assertEqual(peaker.peak(lookahead=2), 'b')
self.assertEqual(peaker.peak(lookahead=3), 'c')