How to use the aiozmq.rpc.util._Packer function in aiozmq

def test_override_translators(self):
        translators = {
            125: (Point, partial(dumps, protocol=HIGHEST_PROTOCOL), loads),
        }
        packer = _Packer(translators=translators)

        pt = Point(3, 4)
        data = dumps(pt, protocol=HIGHEST_PROTOCOL)

        dt = datetime.time(15, 2)

        self.assertEqual(ExtType(125, data), packer.ext_type_pack_hook(pt))
        with self.assertRaisesRegex(TypeError, "Unknown type: "):
            packer.ext_type_pack_hook(dt)

def test_ext_type__timedelta(self, ExtTypeMock):
        packer = _Packer()

        CODE = 124
        td = datetime.timedelta(days=1, hours=2, minutes=3, seconds=4)
        data = dumps(td, protocol=HIGHEST_PROTOCOL)

        self.assertEqual(td, packer.ext_type_unpack_hook(CODE, data))

        packer.ext_type_pack_hook(td)
        ExtTypeMock.assert_called_once_with(CODE, data)

def test_packb_simple(self):
        packer = _Packer()
        self.assertEqual(packb('test'), packer.packb('test'))
        self.assertEqual(packb([123]), packer.packb([123]))
        self.assertEqual(packb((123,)), packer.packb([123]))

def test_ext_type_errors(self):
        packer = _Packer()

        with self.assertRaisesRegex(TypeError, "Unknown type: "):
            packer.ext_type_pack_hook(packer)
        self.assertIn(_Packer, packer._pack_cache)
        self.assertIsNone(packer._pack_cache[_Packer])
        # lets try again just for good coverage
        with self.assertRaisesRegex(TypeError, "Unknown type: "):
            packer.ext_type_pack_hook(packer)

        self.assertEqual(ExtType(1, b''), packer.ext_type_unpack_hook(1, b''))

        # TODO: should be more specific errors
        with self.assertRaises(Exception):
            packer.ext_type_unpack_hook(127, b'bad data')

def test_unpackb_simple(self):
        packer = _Packer()
        self.assertEqual('test', packer.unpackb(packb('test')))
        self.assertEqual((123,), packer.unpackb(packb([123])))
        self.assertEqual((123,), packer.unpackb(packb((123,))))

def test_ext_type__date(self, ExtTypeMock):
        packer = _Packer()

        CODE = 127
        dt = datetime.date(2014, 3, 25)
        data = dumps(dt, protocol=HIGHEST_PROTOCOL)

        self.assertEqual(dt, packer.ext_type_unpack_hook(CODE, data))

        packer.ext_type_pack_hook(dt)
        ExtTypeMock.assert_called_once_with(CODE, data)

def test_ext_type__datetime(self, ExtTypeMock):
        packer = _Packer()

        CODE = 126
        dt = datetime.datetime(2014, 3, 25, 15, 18)
        data = dumps(dt, protocol=HIGHEST_PROTOCOL)

        self.assertEqual(dt, packer.ext_type_unpack_hook(CODE, data))

        packer.ext_type_pack_hook(dt)
        ExtTypeMock.assert_called_once_with(CODE, data)

def test_ext_type__time(self, ExtTypeMock):
        packer = _Packer()

        CODE = 125
        tm = datetime.time(15, 51, 0)
        data = dumps(tm, protocol=HIGHEST_PROTOCOL)

        self.assertEqual(tm, packer.ext_type_unpack_hook(CODE, data))

        packer.ext_type_pack_hook(tm)
        ExtTypeMock.assert_called_once_with(CODE, data)

def test_simple_translators(self):
        translators = {
            0: (Point, partial(dumps, protocol=HIGHEST_PROTOCOL), loads),
        }
        packer = _Packer(translators=translators)

        pt = Point(1, 2)
        data = dumps(pt, protocol=HIGHEST_PROTOCOL)

        self.assertEqual(pt, packer.unpackb(packer.packb(pt)))
        self.assertEqual(ExtType(0, data), packer.ext_type_pack_hook(pt))

        self.assertEqual(pt, packer.ext_type_unpack_hook(0, data))