Testing Router with State

[McPatate]

Hello, I've been trying to no avail to set up tests for a Router which has a state.

From reading the source code in routing.rs, it seems that the trait bounds for tower::Service[Ext] that enable calls to .oneshot() and .call() are only implemented for a Router<()> and not for Router<S>.

axum/axum/src/routing/mod.rs

Line 553 in 978ae63

impl<B> Service<Request<B>> for Router<(), B>

Code example of what I'm attempting to do :

#[derive(Clone)]
struct Container  {
    /// some fields
}

async fn handler(container: State<Container>) {
     /// ...
}

fn router() -> Router<Container> {
    Router::new().route("/", get(handler))
}

#[cfg(test)]
mod tests {
    use super::*;
    use axum::{
        body::Body,
        http::{self, Request, StatusCode},
    };
    use tower::ServiceExt;

    #[tokio::test]
    async fn test_route() {
        let app = router();

        let response = app
            .oneshot(
                Request::builder()
                    .method(http::Method::GET)
                    .uri("/")
                    .body(Body::empty())
                    .unwrap()
            )
            .await
            .unwrap();

        assert_eq!(response.status(), StatusCode::OK);
    }
}

The content of my State is dyn traits, the goal here being to mock my database repositories.

Is what I'm doing sound ? Or should I use Extensions for this use case ?

[davidpdrsn]

You need to call https://docs.rs/axum/latest/axum/routing/struct.Router.html#method.with_state

[McPatate]

Do you mean in my test case ? I'm still getting the error

[McPatate]

For context, the router is merged in another "main" router that has the .with_state() call

[davidpdrsn]

Do you mean in my test case ? I'm still getting the error

Yes. You need to provide the state, otherwise you cannot call the router. How would it handle requests if it doesn't have the state?

For context, the router is merged in another "main" router that has the .with_state() call

Make sure you're specifying the right router type. See https://docs.rs/axum/latest/axum/routing/struct.Router.html#method.with_state for more details.

[McPatate]

The merge works without issue, where I'm having trouble is in my test case. Even when adding the state it still errors at compile :

    #[tokio::test]
    async fn test_route() {
        let app = router();
        let container = Container {};
        app.with_state(container);

        let response = app
            .oneshot(
                Request::builder()
                    .method(http::Method::GET)
                    .uri("/")
                    .body(Body::empty())
                    .unwrap()
            )
            .await
            .unwrap();

        assert_eq!(response.status(), StatusCode::OK);
    }

error[E0599]: the method `oneshot` exists for struct `Router<container::Container>`, but its trait bounds were not satisfied
    |
125 |             .oneshot(
    |              ^^^^^^^
    |
   ::: .cargo/registry/src/github.com-1ecc6299db9ec823/axum-0.6.1/src/routing/mod.rs:64:1
    |
64  | pub struct Router<S = (), B = Body> {
    | -----------------------------------
    | |
    | doesn't satisfy `Router<container::Container>: Service<_>`
    | doesn't satisfy `Router<container::Container>: tower::ServiceExt<_>`
    |
    = note: the following trait bounds were not satisfied:
            `Router<container::Container>: Service<_>`
            which is required by `Router<container::Container>: tower::ServiceExt<_>`
            `&Router<container::Container>: Service<_>`
            which is required by `&Router<container::Container>: tower::ServiceExt<_>`
            `&mut Router<container::Container>: Service<_>`
            which is required by `&mut Router<container::Container>: tower::ServiceExt<_>

[McPatate]

Ah, my bad, this seems to fix things :

    let app = app.with_state(container);

Or calling .with_state() directly on the router() call. Anyhow I think I understand what was wrong.

Thanks for helping me out on this !