False positive for abstract-method

[pylint-bot]

Originally reported by: Claudiu Popa (BitBucket: PCManticore, GitHub: @PCManticore)

---

Given the following code, Pylint emits an abstract-method. We could probably use the new .mro method for new style classes while searching for the abstract method (as it is done for abstract-class-instantiated). For old style classes, using the current approach should suffice.

#!python

import abc

class A(object):
    __metaclass__ = abc.ABCMeta
    @abc.abstractmethod
    def test(self): pass

class X(A):
    pass

class B(X):
    def x(self): pass

    test = x

B().test()

---

• Bitbucket: https://bitbucket.org/logilab/pylint/issue/415

[pylint-bot]

Original comment by Claudiu Popa (BitBucket: PCManticore, GitHub: @PCManticore):

---

Use a mro traversal for finding abstract methods. Closes issue #415.

This patch adds a new unimplemented_abstract_methods in pylint.checkers.utils,
which is used to obtain all the abstract methods which weren't implemented
anywhere in the mro of a class. The code works now by traversing the mro, gathering
all abstract methods encountered at each step and resolving the implemented ones
through either definition or assignment. This disables a couple of false
positives on classes with complex hierarchies.