How do I pass app as a function argument? - Error: is not implemented for impl Future<Output = impl Service<..., Response = ..., Error = ...>>

[SamuelMarks]

Following your https://docs.rs/actix-web/4.9.0/src/actix_web/test/test_utils.rs.html#578

I try to make a simple service:

pub(crate) async fn secret_app_get() -> impl actix_web::dev::Service<
    actix_http::Request,
    Response = actix_web::dev::ServiceResponse<impl actix_http::body::MessageBody>,
    Error = actix_web::error::Error
> {
    actix_web::test::init_service(
        actix_web::App::new()
            .app_data(actix_web::web::Data::new(crate::POOL.clone()))
            .service(
                actix_web::web::scope("/api/v0")
                    .wrap(actix_web::middleware::Compat::new(
                        actix_web_httpauth::middleware::HttpAuthentication::bearer(
                            crate::middleware::bearer::validator,
                        ),
                    ))
                    .service(crate::routes::secret::secret),
            ),
    )
}

And call it in a test:

#[actix_web::test]
async fn test_read_secret() {
    crate::tests::init_db_for_test();
    let app = secret_app_get().await;
}

But I get this error:

error[E0277]: the trait bound `impl std::future::Future<Output = impl actix_web::dev::Service<actix_http::Request, Response = ServiceResponse, Error = actix_web::Error>>: actix_web::dev::Service<actix_http::Request>` is not satisfied
  --> src/tests/routes/secret/helpers.rs:27:3
   |
27 |   > {
   |  ___-
28 | |     actix_web::test::init_service(
29 | |         actix_web::App::new()
30 | |             .app_data(actix_web::web::Data::new(crate::POOL.clone()))
...  |
40 | |     )
41 | | }
   | | ^
   | | |
   | |_unsatisfied trait bound
   |   return type was inferred to be `impl Future<Output = impl Service<..., Response = ..., Error = ...>>` here
   |
   = help: the trait `actix_web::dev::Service<actix_http::Request>` is not implemented for `impl Future<Output = impl Service<..., Response = ..., Error = ...>>`
   = help: the following other types implement trait `actix_web::dev::Service<Req>`:
             `&'a S` implements `actix_web::dev::Service<Req>`
             `&'a mut S` implements `actix_web::dev::Service<Req>`
             `AuthenticationMiddleware<S, F, T>` implements `actix_web::dev::Service<ServiceRequest>`
             `Box<S>` implements `actix_web::dev::Service<Req>`
             `ExpectHandler` implements `actix_web::dev::Service<actix_http::Request>`
             `Next<B>` implements `actix_web::dev::Service<ServiceRequest>`
             `RefCell<S>` implements `actix_web::dev::Service<Req>`
             `UpgradeHandler` implements `actix_web::dev::Service<(actix_http::Request, actix_codec::framed::Framed<T, actix_http::h1::Codec>)>`
           and 33 others