def METHOD_NAME(self):
    # failure
    with self.assertRaises(AssertionError):
        self.test_instance.with_img_type(1234)
    # success
    result = self.test_instance.with_img_type(ImageTypeEnum.PNG)
    self.assertEqual(8, len(result))
    result = self.test_instance.with_img_type(ImageTypeEnum.GEOTIFF)
    self.assertEqual(4, len(result))