Since pytest 6.0.0, pylint complains about unimplemented abstract methods in custom collector

[andy-maier]

Hi, we have implemented a custom pytest collector that takes testcases from YAML files. Starting with pytest 6.0.0, pylint reports the following about that collector:

tests/functiontest/conftest.py:225:0: W0223: Method 'get_closest_marker' is abstract in class 'Node' but is not overridden (abstract-method)
tests/functiontest/conftest.py:225:0: W0223: Method 'gethookproxy' is abstract in class 'FSCollector' but is not overridden (abstract-method)
tests/functiontest/conftest.py:225:0: W0223: Method 'isinitpath' is abstract in class 'FSCollector' but is not overridden (abstract-method)
tests/functiontest/conftest.py:252:0: W0223: Method 'get_closest_marker' is abstract in class 'Node' but is not overridden (abstract-method)

The collector has worked fine for a long time, and it still works fine.

The line pylint reports this on is the class definition of a collector class that is based on pytest.File:

class YamlFile(pytest.File):

    def collect(self):  # The only method in this class
        . . . 

The whole source code is here: https://github.com/pywbem/pywbem/blob/master/tests/functiontest/conftest.py#L225

Versions:

Python 3.8.0 (default, Oct 15 2019, 17:49:23). This happens on all Python 3.x versions we used pytest 6.0.1 with (3.5, 3.6, 3.7, 3.8), on macOS and Ubuntu.

pylint 2.4.4
astroid 2.3.3

platform linux -- Python 3.8.0, pytest-6.0.1, py-1.9.0, pluggy-0.13.1
plugins: cov-2.10.0, yagot-0.5.0, requests-mock-1.8.0

Please let me know in case a collector has to implement these methods.

[bluetech]

None of these methods are abstract (as in abc.abstractmethod) which led to some head scratching, but it seems that pylint considers any method which raises NotImplementedError to be abstract.

get_closest_marker is only marked such because we use raise NotImplementedError() in @overloaded functions. Given how pylint treats these, we can change these to just use pass # pragma: no cover instead. Though ideally pylint would learn to ignore the contents of functions decorated with @overload.

As for gethookproxy and isinitpath, they really are abstract in the sense that the _collectfile() function provided by FSCollector assumes they have been implemented. In the case of your YamlFile collector, you don't use _collectfile so it ends up not mattering. I suppose it is a less than ideal subclassing design. The NotImplemented were added in pytest 6.0.0 by commit be00e12 which fixed some internal typing issues.

I will take a look at resolving this when I get the chance. However we may want to add a quick fix for pytest 6.0.x at least.