pytest-twisted 1.9

Installation

Install the plugin with:

pip install pytest-twisted

Using the plugin

The plugin is available after installation and can be disabled using -p no:twisted.

By default twisted.internet.default is used to install the reactor. This creates the same reactor that import twisted.internet.reactor would. Alternative reactors can be specified using the --reactor option.

Presently only qt5reactor is supported for use with pyqt5 and pytest-qt. This guide describes how to add support for a new reactor.

The reactor is automatically created prior to the first test but can be explicitly installed earlier by calling pytest_twisted.init_default_reactor() or the corresponding function for the desired alternate reactor.

Beware that in situations such as a conftest.py file that the name pytest_twisted may be undesirably detected by pytest as an unknown hook. One alternative is to import pytest_twisted as pt.

inlineCallbacks

Using twisted.internet.defer.inlineCallbacks as a decorator for test functions, which take funcargs, does not work. Please use pytest_twisted.inlineCallbacks instead:

@pytest_twisted.inlineCallbacks
def test_some_stuff(tmpdir):
    res = yield threads.deferToThread(os.listdir, tmpdir.strpath)
    assert res == []

ensureDeferred

Using twisted.internet.defer.ensureDeferred as a decorator for test functions, which take funcargs, does not work. Please use pytest_twisted.ensureDeferred instead:

@pytest_twisted.ensureDeferred
async def test_some_stuff(tmpdir):
    res = await threads.deferToThread(os.listdir, tmpdir.strpath)
    assert res == []

Waiting for deferreds in fixtures

pytest_twisted.blockon allows fixtures to wait for deferreds:

@pytest.fixture
def val():
    d = defer.Deferred()
    reactor.callLater(1.0, d.callback, 10)
    return pytest_twisted.blockon(d)

The twisted greenlet

Some libraries (e.g. corotwine) need to know the greenlet, which is running the twisted reactor. It’s available from the twisted_greenlet funcarg. The following code can be used to make corotwine work with pytest-twisted:

@pytest.fixture(scope="session", autouse=True)
def set_MAIN(request, twisted_greenlet):
    from corotwine import protocol
    protocol.MAIN = twisted_greenlet

That’s (almost) all.

Deprecations

v1.9

pytest.blockon

Use pytest_twisted.blockon

pytest.inlineCallbacks

Use pytest_twisted.inlineCallbacks