def METHOD_NAME(self):
    self.layer.extension_info = {"header": set({"Test Header"})}
    self.assertIsInstance(self.layer.extension_info, dict)
    self.assertIsNotNone(
        self.layer.extension_info.get("header", None), None)
    self.assertIsInstance(
        self.layer.extension_info.get("header", None), set)
    header = self.layer.extension_info.get("header").pop()
    self.assertEqual(header, "Test Header")