def METHOD_NAME() -> None:
    class SubclassMiddleware(AbstractMiddleware):
        exclude_opt_key = "exclude_route"
        async def __call__(self, scope: "Scope", receive: "Receive", send: "Send") -> None:
            async def _send(message: "Message") -> None:
                if message["type"] == "http.response.start":
                    headers = MutableScopeHeaders(message)
                    headers.add("test", str(123))
                await send(message)
                await self.app(scope, receive, _send)
    @get("/", exclude_route=True)
    def handler() -> dict:
        return {"hello": "world"}
    with create_test_client(handler, middleware=[DefineMiddleware(SubclassMiddleware)]) as client:
        response = client.get("/")
        assert "test" not in response.headers