def test_ratecv(self):
        for w in 1, 2, 3, 4:
            self.assertEqual(audioop.ratecv(b'', w, 1, 8000, 8000, None),
                             (b'', (-1, ((0, 0),))))
            self.assertEqual(audioop.ratecv(bytearray(), w, 1, 8000, 8000, None),
                             (b'', (-1, ((0, 0),))))
            self.assertEqual(audioop.ratecv(memoryview(b''), w, 1, 8000, 8000, None),
                             (b'', (-1, ((0, 0),))))
            self.assertEqual(audioop.ratecv(b'', w, 5, 8000, 8000, None),
                             (b'', (-1, ((0, 0),) * 5)))
            self.assertEqual(audioop.ratecv(b'', w, 1, 8000, 16000, None),
                             (b'', (-2, ((0, 0),))))
            self.assertEqual(audioop.ratecv(datas[w], w, 1, 8000, 8000, None)[0],
                             datas[w])
            self.assertEqual(audioop.ratecv(datas[w], w, 1, 8000, 8000, None, 1, 0)[0],
                             datas[w])

        state = None
        d1, state = audioop.ratecv(b'\x00\x01\x02', 1, 1, 8000, 16000, state)
        d2, state = audioop.ratecv(b'\x00\x01\x02', 1, 1, 8000, 16000, state)
        self.assertEqual(d1 + d2, b'\000\000\001\001\002\001\000\000\001\001\002')

        for w in 1, 2, 3, 4:
            d0, state0 = audioop.ratecv(datas[w], w, 1, 8000, 16000, None)
            d, state = b'', None
            for i in range(0, len(datas[w]), w):
                d1, state = audioop.ratecv(datas[w][i:i + w], w, 1,
                                           8000, 16000, state)
                d += d1
            self.assertEqual(d, d0)
            self.assertEqual(state, state0)

        expected = {
            1: packs[1](0, 0x0d, 0x37, -0x26, 0x55, -0x4b, -0x14),
            2: packs[2](0, 0x0da7, 0x3777, -0x2630, 0x5673, -0x4a64, -0x129a),
            3: packs[3](0, 0x0da740, 0x377776, -0x262fca,
                        0x56740c, -0x4a62fd, -0x1298c0),
            4: packs[4](0, 0x0da740da, 0x37777776, -0x262fc962,
                        0x56740da6, -0x4a62fc96, -0x1298bf26),
        }
        for w in 1, 2, 3, 4:
            self.assertEqual(audioop.ratecv(datas[w], w, 1, 8000, 8000, None, 3, 1)[0],
                             expected[w])
            self.assertEqual(audioop.ratecv(datas[w], w, 1, 8000, 8000, None, 30, 10)[0],
                             expected[w])