aiomisc-pytest 1.2.1

Description:

aiomiscpytest 1.2.1

aiomisc pytest plugin
This package contains a plugin for pytest.
Basic usage
Simple usage example:
async def test_sample(event_loop):
f = event_loop.crete_future()
event_loop.call_soon(f.set_result, True)
assert await f

asynchronous fixture example:
import asyncio
import pytest


@pytest.fixture
async def my_fixture(loop):
await asyncio.sleep(0)

# Requires python 3.6+
yield

In case you have to save an instance of an async fixture between tests,
the wrong solution is just changing the fixture scope.
But why it wouldn't work? That's because, in the base scenario, the loop
fixture creates a new event loop instance per test which will be closed after
test teardown. When you have to use an async fixture any caller of
asyncio.get_event_loop() will get the current event loop instance which
will be closed and the next test will run in another event loop.
So the solution is to redefine the loop fixture with the required scope
and custom fixture with the required scope.
import asyncio
import pytest
from aiomisc import entrypoint


@pytest.fixture(scope='module')
def loop():
with entrypoint() as loop:
asyncio.set_event_loop(loop)
yield loop


@pytest.fixture(scope='module')
async def sample_fixture(loop):
yield 1


LOOP_ID = None


async def test_using_fixture(sample_fixture):
global LOOP_ID
LOOP_ID = id(asyncio.get_event_loop())
assert sample_fixture == 1


async def test_not_using_fixture(loop):
assert id(loop) == LOOP_ID

pytest markers
Package contains some useful markers for pytest:

catch_loop_exceptions - uncaught event loop exceptions will failling test.
forbid_get_event_loop - forbids call asyncio.get_event_loop
during test case.

import asyncio
import pytest


@pytest.mark.forbid_get_event_loop
async def test_with_get_loop():
def switch_context():
loop = asyncio.get_event_loop()
future = loop.create_future()
loop.call_soon(future.set_result, True)
return future

with pytest.raises(Exception):
await switch_context()


# Test will be failed
@pytest.mark.catch_loop_exceptions
async def test_with_errors(loop):
async def fail():
# switch context
await asyncio.sleep(0)
raise Exception()

loop.create_task(fail())
await asyncio.sleep(0.1)
return

Passing default context
import pytest

@pytest.fixture
def default_context():
return {
'foo': 'bar',
'bar': 'foo',
}

Testing services
Redefine services fixture in your test module:
import aiomisc
import pytest


class SimpleServie(aiomisc.Service):
async def start(self) -> None:
pass


@pytest.fixture
def services():
return [SimpleServie()]

Event loop policy overriding
import asyncio
import pytest
import tokio
import uvloop

policy_ids = ('uvloop', 'asyncio', 'tokio')
policies = (uvloop.EventLoopPolicy(),
asyncio.DefaultEventLoopPolicy(),
tokio.EventLoopPolicy())

@pytest.fixture(params=policies, ids=policy_ids)
def event_loop_policy(request):
return request.param

Thread pool overriding
import pytest
from aiomisc.thread_pool import ThreadPoolExecutor
import concurrent.futures

thread_pool_ids = ('aiomisc pool', 'default pool')
thread_pool_implementation = (ThreadPoolExecutor,
concurrent.futures.ThreadPoolExecutor)


@pytest.fixture(params=thread_pool_implementation, ids=thread_pool_ids)
def thread_pool_executor(request):
return request.param

entrypoint arguments
import pytest

@pytest.fixture
def entrypoint_kwargs() -> dict:
return dict(log_config=False)

aiohttp test client
import pytest
from myapp.services.rest import REST


@pytest.fixture
def rest_port(aiomisc_unused_port_factory):
return aiomisc_unused_port_factory()


@pytest.fixture
def rest_service(rest_port):
return REST(port=rest_port)


@pytest.fixture
def services(rest_service):
return [rest_service]


@pytest.fixture
def api_client(api_service):
test_srv = TestServer(
app=rest_service.app,
port=arguments.port,
)

return TestClient(test_srv)

...

TCPProxy
Simple TCP proxy for emulate network problems. Available as fixture tcp_proxy
Examples:
import asyncio
import time

import pytest

import aiomisc


class EchoServer(aiomisc.service.TCPServer):
async def handle_client(
self, reader: asyncio.StreamReader,
writer: asyncio.StreamWriter
):
chunk = await reader.read(65534)
while chunk:
writer.write(chunk)
chunk = await reader.read(65534)

writer.close()
await writer.wait_closed()


@pytest.fixture()
def server_port(aiomisc_unused_port_factory) -> int:
return aiomisc_unused_port_factory()


@pytest.fixture()
def services(server_port, localhost):
return [EchoServer(port=server_port, address=localhost)]


@pytest.fixture()
async def proxy(tcp_proxy, localhost, server_port):
async with tcp_proxy(localhost, server_port) as proxy:
yield proxy


async def test_proxy_client_close(proxy):
reader, writer = await proxy.create_client()
payload = b"Hello world"

writer.write(payload)
response = await asyncio.wait_for(reader.read(1024), timeout=1)

assert response == payload

assert not reader.at_eof()
await proxy.disconnect_all()

assert await asyncio.wait_for(reader.read(), timeout=1) == b""
assert reader.at_eof()


async def test_proxy_client_slow(proxy):
read_delay = 0.1
write_delay = 0.2

# Emulation of asymmetric and slow ISP
with proxy.slowdown(read_delay, write_delay):
reader, writer = await proxy.create_client()
payload = b"Hello world"

delta = -time.monotonic()

writer.write(payload)
await asyncio.wait_for(reader.read(1024), timeout=2)

delta += time.monotonic()

assert delta >= read_delay + write_delay


async def test_proxy_client_with_processor(proxy):
processed_request = b"Never say hello"

# Patching protocol functions
proxy.set_content_processors(
# Process data from client to server
lambda _: processed_request,

# Process data from server to client
lambda chunk: chunk[::-1],
)

reader, writer = await proxy.create_client()
writer.write(b'nevermind')

response = await reader.read(16)

assert response == processed_request[::-1]