pytest_twisted hides erroneous yield from non-deferred objects

[jan-matejka]

% cat a.py
from pytest_twisted import inlineCallbacks

def do_io():
    return None # should return Deferred

@inlineCallbacks
def test_foo():
    yield do_io()

% pytest ./a.py
============================================================================================================= test session starts =============================================================================================================
platform linux -- Python 3.7.3, pytest-4.6.3, py-1.8.0, pluggy-0.12.0
rootdir: /home/yac
plugins: twisted-1.10
collected 1 item

a.py .                                                                                                                                                                                                                                  [100%]

========================================================================================================== 1 passed in 0.02 seconds ===========================================================================================================

[graingert]

This is the intended behaviour of a feature in twisted.
pytest_twisted.inlineCallbacks behaves exactly like:
https://twistedmatrix.com/documents/current/api/twisted.internet.defer.html#inlineCallbacks except it passes along the function signature so pytest can inject

Use an async def and @pytest_twisted.ensureDeferred if you want the modern, more explicit coroutine behaviour