# -*- coding: utf-8; -*-

from ...syntax import macros, test, warn # noqa: F401

from ...test.fixtures import session, testset

from io import BytesIO, SEEK_SET

from .fixtures import nettest

from ..msg import encodemsg, MessageDecoder

from ..util import bytessource, streamsource, socketsource

def runtests():

with testset("sans-IO"):

with testset("basic usage"):

# Encode a message:

rawdata = b"hello world"

message = encodemsg(rawdata)

# Decode a message:

decoder = MessageDecoder(bytessource(message))

test[decoder.decode() == b"hello world"]

test[decoder.decode() is None] # The message should have been consumed by the first decode.

# Decoding a message gets a whole message and only that message.

with testset("decode robustness"):

bio = BytesIO()

bio.write(message)

bio.write(b"junk junk junk")

bio.seek(0, SEEK_SET)

decoder = MessageDecoder(streamsource(bio))

test[decoder.decode() == b"hello world"]

test[decoder.decode() is None]

# - Messages are received in order.

# - Any leftover bytes already read into the receive buffer by the previous decode

# are consumed *from the buffer* by the next decode. This guarantees it doesn't

# matter if the transport does not honor message boundaries (which is indeed the

# whole point of having this protocol).

# - Note this means that should you wish to stop receiving messages on a particular

# source, and resume reading a raw stream from it instead, you must manually prepend

# the final contents of the receive buffer (`decoder.get_buffered_data()`) to whatever

# data you later receive from that source (since that data has already been placed

# into the receive buffer, so it is no longer available at the source).

# - So it's recommended to have a dedicated channel to communicate using messages,

# e.g. a dedicated TCP connection on which all communication is done with messages.

# This way you don't need to care about the receive buffer.

with testset("message ordering"):

bio = BytesIO()

bio.write(encodemsg(b"hello world"))

bio.write(encodemsg(b"hello again"))

bio.seek(0, SEEK_SET)

decoder = MessageDecoder(streamsource(bio))

test[decoder.decode() == b"hello world"]

test[decoder.decode() == b"hello again"]

test[decoder.decode() is None]

# Synchronization to message start is performed upon decode.

# It doesn't matter if there is junk between messages (the junk is discarded).

with testset("stream synchronization"):

bio = BytesIO()

bio.write(encodemsg(b"hello world"))

bio.write(b"junk junk junk")

bio.write(encodemsg(b"hello again"))

bio.seek(0, SEEK_SET)

decoder = MessageDecoder(streamsource(bio))

test[decoder.decode() == b"hello world"]

test[decoder.decode() == b"hello again"]

test[decoder.decode() is None]

# Junk containing sync bytes (0xFF) does not confuse or hang the decoder.

with testset("junk containing sync bytes"):

bio = BytesIO()

bio.write(encodemsg(b"hello world"))

bio.write(b"\xff" * 10)

bio.write(encodemsg(b"hello again"))

bio.seek(0, SEEK_SET)

decoder = MessageDecoder(streamsource(bio))

test[decoder.decode() == b"hello world"]

test[decoder.decode() == b"hello again"]

test[decoder.decode() is None]

with testset("with TCP sockets"):

def server1(sock):

decoder = MessageDecoder(socketsource(sock))

data = decoder.decode()

return data

def client1(sock):

sock.sendall(encodemsg(b"hello world"))

test[nettest(server1, client1) == b"hello world"]

def server2(sock):

decoder = MessageDecoder(socketsource(sock))

data = decoder.decode()

return data

def client2(sock):

sock.sendall(encodemsg(b"hello world"))

sock.sendall(encodemsg(b"hello again"))

test[nettest(server2, client2) == b"hello world"]

def server3(sock):

decoder = MessageDecoder(socketsource(sock))

data = []

data.append(decoder.decode())

data.append(decoder.decode())

return data

def client3(sock):

sock.sendall(encodemsg(b"hello world"))

sock.sendall(encodemsg(b"hello again"))

test[nettest(server3, client3) == [b"hello world", b"hello again"]]

if __name__ == '__main__': # pragma: no cover

with session(__file__):

runtests()