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"""Utilities for testing stream operators."""
from __future__ import annotations
import asyncio
from unittest.mock import Mock
from contextlib import contextmanager
import pytest
from .core import StreamEmpty, streamcontext, pipable_operator
from typing import TYPE_CHECKING, Any, Callable, List
if TYPE_CHECKING:
from _pytest.fixtures import SubRequest
from aiostream.core import Stream
__all__ = ["add_resource", "assert_run", "event_loop"]
@pipable_operator
async def add_resource(source, cleanup_time):
"""Simulate an open resource in a stream operator."""
try:
loop = asyncio.get_event_loop()
loop.open_resources += 1
loop.resources += 1
async with streamcontext(source) as streamer:
async for item in streamer:
yield item
finally:
try:
await asyncio.sleep(cleanup_time)
finally:
loop.open_resources -= 1
def compare_exceptions(
exc1: Exception,
exc2: Exception,
) -> bool:
"""Compare two exceptions together."""
return exc1 == exc2 or exc1.__class__ == exc2.__class__ and exc1.args == exc2.args
async def assert_aiter(
source: Stream,
values: List[Any],
exception: Exception | None = None,
) -> None:
"""Check the results of a stream using a streamcontext."""
results = []
exception_type = (type(exception),) if exception else ()
try:
async with streamcontext(source) as streamer:
async for item in streamer:
results.append(item)
except exception_type as exc:
assert exception is not None
assert compare_exceptions(exc, exception)
else:
assert exception is None
assert results == values
async def assert_await(
source: Stream,
values: List[Any],
exception: Exception | None = None,
) -> None:
"""Check the results of a stream using by awaiting it."""
exception_type = (type(exception),) if exception else ()
try:
result = await source
except StreamEmpty:
assert values == []
assert exception is None
except exception_type as exc:
assert exception is not None
assert compare_exceptions(exc, exception)
else:
assert result == values[-1]
assert exception is None
@pytest.fixture(params=[assert_aiter, assert_await], ids=["aiter", "await"])
def assert_run(request: SubRequest) -> Callable:
"""Parametrized fixture returning a stream runner."""
return request.param
@pytest.fixture
def event_loop():
"""Fixture providing a test event loop.
The event loop simulate and records the sleep operation,
available as event_loop.steps
It also tracks simulated resources and make sure they are
all released before the loop is closed.
"""
class TimeTrackingTestLoop(asyncio.BaseEventLoop):
stuck_threshold = 100
def __init__(self):
super().__init__()
self._time = 0
self._timers = []
self._selector = Mock()
self.clear()
# Loop internals
def _run_once(self):
super()._run_once()
# Update internals
self.busy_count += 1
self._timers = sorted(when for when in self._timers if when > loop.time())
# Time advance
if self.time_to_go:
when = self._timers.pop(0)
step = when - loop.time()
self.steps.append(step)
self.advance_time(step)
self.busy_count = 0
def _process_events(self, event_list):
return
def _write_to_self(self):
return
# Time management
def time(self):
return self._time
def advance_time(self, advance):
if advance:
self._time += advance
def call_at(self, when, callback, *args, **kwargs):
self._timers.append(when)
return super().call_at(when, callback, *args, **kwargs)
@property
def stuck(self):
return self.busy_count > self.stuck_threshold
@property
def time_to_go(self):
return self._timers and (self.stuck or not self._ready)
# Resource management
def clear(self):
self.steps = []
self.open_resources = 0
self.resources = 0
self.busy_count = 0
@contextmanager
def assert_cleanup(self):
self.clear()
yield self
assert self.open_resources == 0
self.clear()
loop = TimeTrackingTestLoop()
asyncio.set_event_loop(loop)
with loop.assert_cleanup():
yield loop
loop.close()
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