def testV():

    # test VI
    vector = numpy.array((1,2,3), int)
    assert packet.pack('V',vector) == struct.pack('<ccIiii', b'V', b'I', 3, 1, 2, 3)

    (type, rvector) = packet.unpack_stream(
        io.BytesIO(struct.pack('<ccIiii', b'V', b'I', 3, 1, 2, 3)))
    assert type == 'V'
    assert numpy.all(rvector == vector)

    vector = numpy.array((1,-2,3), int)
    assert packet.pack('V',vector) == struct.pack('<ccIiii', b'V', b'I', 3, 1, -2, 3)

    (type, rvector) = packet.unpack_stream(
        io.BytesIO(struct.pack('<ccIiii', b'V', b'I', 3, 1, -2, 3)))
    assert type == 'V'
    assert numpy.all(rvector == vector)

    # test VF
    vector = numpy.array((1.3,-2,3), numpy.float32)
    assert packet.pack('V',vector) == struct.pack('<ccIfff', b'V', b'F', 3, 1.3, -2, 3)

    (type, rvector) = packet.unpack_stream(
        io.BytesIO(struct.pack('<ccIfff', b'V', b'F', 3, 1.3, -2, 3)))
    assert type == 'V'
    assert numpy.all(rvector == vector)

    # test VD
    vector = numpy.array((1.3,-2,3), float)
    assert packet.pack('V',vector) == struct.pack('<ccIddd', b'V', b'D', 3, 1.3, -2, 3)

    (type, rvector) = packet.unpack_stream(
        io.BytesIO(struct.pack('<ccIddd', b'V', b'D', 3, 1.3, -2, 3)))
    assert type == 'V'
    assert numpy.all(rvector == vector)