70 lines
2.1 KiB
Python
70 lines
2.1 KiB
Python
from __future__ import annotations
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from contextlib import AbstractContextManager, contextmanager
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from typing import TYPE_CHECKING
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from .. import _core
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if TYPE_CHECKING:
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from collections.abc import Generator
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@contextmanager
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def _assert_yields_or_not(expected: bool) -> Generator[None, None, None]:
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"""Check if checkpoints are executed in a block of code."""
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__tracebackhide__ = True
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task = _core.current_task()
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orig_cancel = task._cancel_points
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orig_schedule = task._schedule_points
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try:
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yield
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if expected and (
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task._cancel_points == orig_cancel or task._schedule_points == orig_schedule
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):
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raise AssertionError("assert_checkpoints block did not yield!")
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finally:
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if not expected and (
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task._cancel_points != orig_cancel or task._schedule_points != orig_schedule
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):
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raise AssertionError("assert_no_checkpoints block yielded!")
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def assert_checkpoints() -> AbstractContextManager[None]:
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"""Use as a context manager to check that the code inside the ``with``
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block either exits with an exception or executes at least one
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:ref:`checkpoint <checkpoints>`.
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Raises:
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AssertionError: if no checkpoint was executed.
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Example:
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Check that :func:`trio.sleep` is a checkpoint, even if it doesn't
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block::
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with trio.testing.assert_checkpoints():
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await trio.sleep(0)
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"""
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__tracebackhide__ = True
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return _assert_yields_or_not(True)
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def assert_no_checkpoints() -> AbstractContextManager[None]:
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"""Use as a context manager to check that the code inside the ``with``
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block does not execute any :ref:`checkpoints <checkpoints>`.
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Raises:
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AssertionError: if a checkpoint was executed.
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Example:
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Synchronous code never contains any checkpoints, but we can double-check
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that::
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send_channel, receive_channel = trio.open_memory_channel(10)
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with trio.testing.assert_no_checkpoints():
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send_channel.send_nowait(None)
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"""
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__tracebackhide__ = True
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return _assert_yields_or_not(False)
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