pytest-asyncio travis-ci python

Pytest support for asyncio.

2 years after

pytest-asyncio: pytest support for asyncio

.. image:: https://img.shields.io/pypi/v/pytest-asyncio.svg :target: https://pypi.python.org/pypi/pytest-asyncio .. image:: https://travis-ci.org/pytest-dev/pytest-asyncio.svg?branch=master :target: https://travis-ci.org/pytest-dev/pytest-asyncio .. image:: https://coveralls.io/repos/pytest-dev/pytest-asyncio/badge.svg :target: https://coveralls.io/r/pytest-dev/pytest-asyncio

pytest-asyncio is an Apache2 licensed library, written in Python, for testing asyncio code with pytest.

asyncio code is usually written in the form of coroutines, which makes it slightly more difficult to test using normal testing tools. pytest-asyncio provides useful fixtures and markers to make testing easier.

.. code-block:: python

@pytest.mark.asyncio
async def test_some_asyncio_code():
    res = await library.do_something()
    assert b'expected result' == res

or, if you're using the pre-Python 3.5 syntax:

.. code-block:: python

@pytest.mark.asyncio
def test_some_asyncio_code():
    res = yield from library.do_something()
    assert b'expected result' == res

pytest-asyncio has been strongly influenced by pytest-tornado_.

.. _pytest-tornado: https://github.com/eugeniy/pytest-tornado

Features

  • fixtures for creating and injecting versions of the asyncio event loop
  • fixtures for injecting unused tcp ports
  • pytest markers for treating tests as asyncio coroutines
  • easy testing with non-default event loops

Installation

To install pytest-asyncio, simply:

.. code-block:: bash

$ pip install pytest-asyncio

This is enough for pytest to pick up pytest-asyncio.

Fixtures

event_loop

Creates and injects a new instance of the default asyncio event loop. By
default, the loop will be closed at the end of the test (i.e. the default
fixture scope is ``function``).

Note that just using the ``event_loop`` fixture won't make your test function
a coroutine. You'll need to interact with the event loop directly, using methods
like ``event_loop.run_until_complete``. See the ``pytest.mark.asyncio`` marker
for treating test functions like coroutines.

Simply using this fixture will not set the generated event loop as the
default asyncio event loop, or change the asyncio event loop policy in any way.
Use ``pytest.mark.asyncio`` for this purpose.

.. code-block:: python

    def test_http_client(event_loop):
        url = 'http://httpbin.org/get'
        resp = event_loop.run_until_complete(http_client(url))
        assert b'HTTP/1.1 200 OK' in resp

This fixture can be easily overridden in any of the standard pytest locations
(e.g. directly in the test file, or in ``conftest.py``) to use a non-default
event loop. This will take effect even if you're using the
``pytest.mark.asyncio`` marker and not the ``event_loop`` fixture directly.

.. code-block:: python

    @pytest.yield_fixture()
    def event_loop():
        loop = MyCustomLoop()
        yield loop
        loop.close()

If the ``pytest.mark.asyncio`` marker is applied, a pytest hook will
ensure the produced loop is either set as the default global loop, or a special,
error-throwing event loop policy is installed as the default policy (depending
on the ``forbid_global_loop`` parameter). Fixtures depending on the
``event_loop`` fixture can expect the policy to be properly modified when they
run.

``event_loop_process_pool``

The event_loop_process_pool fixture is almost identical to the event_loop fixture, except the created event loop will have a concurrent.futures.ProcessPoolExecutor set as the default executor.

unused_tcp_port

Finds and yields a single unused TCP port on the localhost interface. Useful for
binding temporary test servers.

``unused_tcp_port_factory``

A callable which returns a different unused TCP port each invocation. Useful when several unused TCP ports are required in a test.

.. code-block:: python

def a_test(unused_tcp_port_factory):
    port1, port2 = unused_tcp_port_factory(), unused_tcp_port_factory()
    ...

Markers

pytest.mark.asyncio(forbid_global_loop=False)

Mark your test coroutine with this marker and pytest will execute it as an
asyncio task using the event loop provided by the ``event_loop`` fixture. See
the introductory section for an example.

The event loop used can be overriden by overriding the ``event_loop`` fixture
(see above).

If ``forbid_global_loop`` is true, ``asyncio.get_event_loop()`` will result
in exceptions, ensuring your tests are always passing the event loop explicitly.

In order to make your test code a little more concise, the pytest |pytestmark|_
feature can be used to mark entire modules or classes with this marker.
Only test coroutines will be affected (by default, coroutines prefixed by
``test_``), so, for example, fixtures are safe to define.

.. code-block:: python

    import asyncio
    import pytest

    # All test coroutines will be treated as marked.
    pytestmark = pytest.mark.asyncio(forbid_global_loop=True)

    async def test_example(event_loop):
        """No marker!"""
        await asyncio.sleep(0, loop=event_loop)

.. |pytestmark| replace:: ``pytestmark``
.. _pytestmark: http://doc.pytest.org/en/latest/example/markers.html#marking-whole-classes-or-modules

``pytest.mark.asyncio_process_pool(forbid_global_loop=False)``

The asyncio_process_pool marker is almost identical to the asyncio marker, except the event loop used will have a concurrent.futures.ProcessPoolExecutor set as the default executor.

Changelog

0.6.0 (UNRELEASED)

- ``pytestmark`` now works on both module and class level.

0.5.0 (2016-09-07)
  • Introduced a changelog. #31 <https://github.com/pytest-dev/pytest-asyncio/issues/31>_
  • The event_loop fixture is again responsible for closing itself. This makes the fixture slightly harder to correctly override, but enables other fixtures to depend on it correctly. #30 <https://github.com/pytest-dev/pytest-asyncio/issues/30>_
  • Deal with the event loop policy by wrapping a special pytest hook, pytest_fixture_setup. This allows setting the policy before fixtures dependent on the event_loop fixture run, thus allowing them to take advantage of the forbid_global_loop parameter. As a consequence of this, we now depend on pytest 3.0. #29 <https://github.com/pytest-dev/pytest-asyncio/issues/29>_

0.4.1 (2016-06-01)

- Fix a bug preventing the propagation of exceptions from the plugin.
  `#25 <https://github.com/pytest-dev/pytest-asyncio/issues/25>`_

0.4.0 (2016-05-30)
  • Make event_loop fixtures simpler to override by closing them in the plugin, instead of directly in the fixture. #21 <https://github.com/pytest-dev/pytest-asyncio/pull/21>_
  • Introduce the forbid_global_loop parameter. #21 <https://github.com/pytest-dev/pytest-asyncio/pull/21>_

0.3.0 (2015-12-19)

- Support for Python 3.5 ``async``/``await`` syntax.
  `#17 <https://github.com/pytest-dev/pytest-asyncio/pull/17>`_

0.2.0 (2015-08-01)
  • unused_tcp_port_factory fixture. #10 <https://github.com/pytest-dev/pytest-asyncio/issues/10>_

0.1.1 (2015-04-23)


Initial release.

Contributing
------------
Contributions are very welcome. Tests can be run with ``tox``, please ensure
the coverage at least stays the same before you submit a pull request.

Related Repositories

awesome-python-cn

awesome-python-cn

Python资源大全中文版,包括:Web框架、网络爬虫、模板引擎、数据库、数据可视化、图片处理等,由伯乐在线持续更新。 ...

awesome-asyncio

awesome-asyncio

A curated list of awesome Python asyncio frameworks, libraries, software and res ...

aiokafka

aiokafka

asyncio client for kafka ...

awesome-europython2015

awesome-europython2015

Materials from europython2015 ...

asyncio_time_travel

asyncio_time_travel

Asyncio Time Travel Loop ...


Top Contributors

Tinche nicoddemus asvetlov dirn a7p agronholm leifurhauks Lucretiel GMLudo

Releases

-   v0.5.0 zip tar
-   v0.4.1 zip tar
-   v0.4.0 zip tar
-   v0.3.0 zip tar
-   v0.2.0 zip tar
-   v0.1.3 zip tar
-   v0.1.2 zip tar
-   v0.1.1 zip tar