def METHOD_NAME(self):
    """generate_thumbnail does not fail if file doesn't actually exist."""
    image = ImageAttachment(content_object=self.obj, creator=self.user)
    with open("kitsune/upload/tests/media/test.jpg", "rb") as f:
        up_file = File(f)
        image.file.save(up_file.name, up_file, save=True)
    # The field will be set but the file isn't there.
    os.remove(image.file.path)
    generate_thumbnail("upload.ImageAttachment", image.id, "file", "thumbnail")