Descriptor tests

descriptor_tests.py

import unittest
from weakref import WeakKeyDictionary


class Skippable(object):
    def __init__(self, field_name):
        self.data = WeakKeyDictionary()
        self.field_name = field_name

    def __get__(self, instance, owner):
        def f():
            if instance.a == 1:
                message = 'Skipping test for {}.'.format(self.field_name)
                return unittest.skip(message)
            instance.assertEqual(getattr(instance, self.field_name), 1)
        f.__doc__ = "Test that `{}` has a value.".format(self.field_name)
        return f

    def __set__(self, instance, value):
        pass


class MyTestCase(unittest.TestCase):
    test_a = Skippable('a')
    test_b = Skippable('b')

    a = 1
    b = 2


class MyTestCase2(unittest.TestCase):
    test_a = Skippable('a')
    test_b = Skippable('b')

    a = 2
    b = 3


if __name__ == '__main__':
    unittest.main(verbosity=2)