def METHOD_NAME(self):
    form_field = self.custom_field_choices.get_form_field()
    self.assertIsInstance(form_field, forms.ChoiceField)
    self.assertEqual(
        form_field.choices,
        [
            ('qwerty', 'qwerty'),
            ('asdfgh', 'asdfgh'),
            ('zxcvbn', 'zxcvbn'),
        ]
    )