'Ensure that the correct list of superclasses is assembled.'

def test_superclasses(self):

    class Animal(Document, ):
        meta = {'allow_inheritance': True}
    class Fish(Animal, ):
        pass
    class Guppy(Fish, ):
        pass
    class Mammal(Animal, ):
        pass
    class Dog(Mammal, ):
        pass
    class Human(Mammal, ):
        pass
    self.assertEqual(Animal._superclasses, ())
    self.assertEqual(Fish._superclasses, ('Animal',))
    self.assertEqual(Guppy._superclasses, ('Animal', 'Animal.Fish'))
    self.assertEqual(Mammal._superclasses, ('Animal',))
    self.assertEqual(Dog._superclasses, ('Animal', 'Animal.Mammal'))
    self.assertEqual(Human._superclasses, ('Animal', 'Animal.Mammal'))
