Mock S3 client using TestConnection

[riquito]

I'm trying to use aws_smithy_client::test_connection::TestConnection as connector for aws_sdk_s3::Client, but I'm failing to grasp what's missing in my implementation.

use aws_sdk_s3::Client as S3Client;
use aws_sdk_s3::Credentials;
use aws_smithy_client::test_connection::TestConnection;
use aws_smithy_http::body::SdkBody;

fn mocked_s3_client() -> S3Client {
    let credentials = Credentials::new("mock_key", "mock_secret", None, None, "mock_provider");

    let s3_config = aws_sdk_s3::Config::builder()
        .credentials_provider(credentials)
        .build();

    let conn = TestConnection::new(vec![(
        // Request
        http::Request::builder().body(SdkBody::from("foo")).unwrap(),
        // Response
        http::Response::builder()
            .status(200)
            .body(SdkBody::from("bar"))
            .unwrap(),
    )]);

    S3Client::from_conf_conn(s3_config, conn)
}

The code fails to build with

error[E0277]: the trait bound `TestConnection<SdkBody>: tower_service::Service<http::Request<aws_smithy_http::body::SdkBody>>` is not satisfied
     --> some-project/tests/some-test.rs:23:41
      |
23    |     S3Client::from_conf_conn(s3_config, conn)
      |     ------------------------            ^^^^ the trait `tower_service::Service<http::Request<aws_smithy_http::body::SdkBody>>` is not implemented for `TestConnection<SdkBody>`
      |     |
      |     required by a bound introduced by this call
      |
      = help: the trait `tower_service::Service<http::Request<SdkBody>>` is implemented for `TestConnection<B>`
      = note: required because of the requirements on the impl of `aws_smithy_client::bounds::SmithyConnector` for `TestConnection<SdkBody>`
note: required by a bound in `aws_sdk_s3::Client::from_conf_conn`
     --> /home/some-user/.cargo/registry/src/github.com-1ecc6299db9ec823/aws-sdk-s3-0.16.0/src/client.rs:14121:12
      |
14121 |         C: aws_smithy_client::bounds::SmithyConnector<Error = E> + Send + 'static,
      |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `aws_sdk_s3::Client::from_conf_conn`

My (clearly wrong) impression is that TestConnection<B> implements the trait, and the specialized TestConnection<SdkBody> should implement it too.

I then tried to implement the trait looking at a previous discussion #253, with similar results.

use aws_sdk_s3::Client as S3Client;
use aws_sdk_s3::Credentials;
use aws_smithy_client::test_connection::TestConnection;
use aws_smithy_http::body::SdkBody;

use aws_smithy_http::result::ConnectorError;
use std::future::Future;
use std::pin::Pin;

#[derive(Clone)]
struct CustomTestConnection(TestConnection<SdkBody>);

impl tower::Service<http::Request<SdkBody>> for CustomTestConnection {
    type Response = http::Response<SdkBody>;
    type Error = ConnectorError;

    type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;

    fn poll_ready(
        &mut self,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Result<(), Self::Error>> {
        self.0
            .poll_ready(cx)
            .map_err(|e| ConnectorError::io(e.into()))
    }

    fn call(&mut self, req: http::Request<SdkBody>) -> Self::Future {
        let inner = self.0.call(req);
        let fut = async move {
            let resp = inner.await;
            resp.map(|ok| ok.map(SdkBody::from))
                .map_err(|e| ConnectorError::io(e.into()))
        };
        Box::pin(fut)
    }
}

fn mocked_s3_client() -> S3Client {
    let credentials = Credentials::new("mock_key", "mock_secret", None, None, "mock_provider");

    let s3_config = aws_sdk_s3::Config::builder()
        .credentials_provider(credentials)
        .build();

    let conn = TestConnection::new(vec![(
        // Request
        http::Request::builder().body(SdkBody::from("foo")).unwrap(),
        // Response
        http::Response::builder()
            .status(200)
            .body(SdkBody::from("bar"))
            .unwrap(),
    )]);

    let conn2 = CustomTestConnection(conn);

    S3Client::from_conf_conn(s3_config, conn2)
}

error[E0277]: the trait bound `CustomTestConnection: Service<http::Request<aws_smithy_http::body::SdkBody>>` is not satisfied
     --> some-project/tests/some-test.rs:58:41
      |
58    |     S3Client::from_conf_conn(s3_config, conn2)
      |     ------------------------            ^^^^^ the trait `Service<http::Request<aws_smithy_http::body::SdkBody>>` is not implemented for `CustomTestConnection`
      |     |
      |     required by a bound introduced by this call
      |
      = help: the trait `Service<http::Request<SdkBody>>` is implemented for `CustomTestConnection`

Any suggestion would be appreciated

[rcoh]

Your code looks right to me—my guess is that you have a incompatible version of aws_smithy_client in your tree—Can you look at https://crates.io/crates/aws-sdk-s3/0.16.0/dependencies for your version of the S3 client and ensure you have the matching versions of aws-smithy-client and aws-smithy-http?

[riquito]

Your guess was right, one dependency was off (not sure which one, today is release day so I ended up bumping them all to latest)

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.