Port tests call fixtures directly

[olaan]

As the title says.

_______________ ERROR at setup of test_attach_endpoint_to_inport _______________
    @pytest.fixture
    def inport():
>       return InPort("inport", actor())
E       RemovedInPytest4Warning: Fixture "actor" called directly.
E       Fixtures are not meant to be called directly, are created automatically when test functions request them as parameters. See https://docs.pytest.org/en/latest/fixture.html for more information.