def METHOD_NAME(cls):
    super().METHOD_NAME()
    cls.sth_related = SomethingRelated.objects.create(name='Rel1')
    cls.pol_1 = PolymorphicModelTest.objects.create(
        name='Pol1',
        sth_related=cls.sth_related
    )
    cls.pol_2 = PolymorphicModelTest.objects.create(
        name='Pol2',
        sth_related=cls.sth_related
    )
    cls.pol_3 = PolymorphicModelTest2.objects.create(
        name='Pol3',
        another_related=cls.sth_related,
    )