def test_preprocessorCollection(self):
        a, b, c = object(), object(), object()

        class Base(object):
            preprocessors = [a]

        class OtherBase(object):
            preprocessors = [b]

        class Derived(Base, OtherBase):
            preprocessors = [c]

        inst = Derived()
        self.assertEqual(
            rend._getPreprocessors(inst),
            [a, b, c])

        d = object()
        inst.preprocessors = [d]
        self.assertEqual(
            rend._getPreprocessors(inst),
            [d])
Test that preprocessors from all the base classes of an instance are
dataset/ETHPy150Open twisted/nevow/nevow/test/test_athena.py/UtilitiesTests.test_preprocessorCollection